Changes in Serving Size, Calories, and Sodium Content in Processed Foods From 2009 to 2015.

PubMed

Clapp, Jenifer E; Niederman, Sarah A; Leonard, Elizabeth; Curtis, Christine J

2018-03-15

Approximately 60% of the American diet comes from processed foods, which makes improving their nutritional quality important for Americans' health. The objective of this study was to measure changes in serving sizes, calories, and sodium in top-selling processed foods that were on the market in 2009 and 2015. We analyzed products in the top 80% of sales in the 54 processed food categories with consistent serving sizes and sales metrics that were on the market in both 2009 and 2015. Mean serving size, calories (per serving and density), sodium (per serving and density), and sales were calculated for 2,979 branded processed food products. For each stratification of calorie density and sodium density (decreased, increased, or did not change), we calculated the mean serving size, calorie density, sodium density, and sales for each year. From 2009 to 2015, we found decreases in serving size (-2.3%, P < .001), calories per serving (-2.0%, P < .001), calorie density (-1.1%, P < .001), sodium per serving (-7.6%, P < .001), and sodium density (-6.0%, P < .001). A decrease in calorie density did not correspond to an increase in sodium density or vice versa. A decline in sales was observed regardless of whether calorie density or sodium density decreased, increased, or did not change. Reductions in calorie and sodium density occurred in tandem, suggesting that manufacturers reformulated for more than one health goal at the same time. Instead of unintended negative consequences of encouraging companies to reformulate for one nutrient, an overall net nutritional benefit occurred.

From Carbonatite to Ikaite: How high-T carbonates are transformed into low-T carbonate minerals in SW Greenland

NASA Astrophysics Data System (ADS)

Stockmann, G. J.; Tollefsen, E.; Ranta, E.; Skelton, A.; Sturkell, E.; Lundqvist, L.

2015-12-01

The 1300 Ma Grønnedal-Íka igneous complex in southwest Greenland comprises nepheline syenites and carbonatites. It belongs to a suite of intrusions formed 1300-1100 Ma ago referred to as the Gardar period. In modern time (the last ca. 8000 years), fluid-rock interactions involving the nepheline syenites and carbonatites gives rise to about one thousand submarine columns made of the rare low-T mineral ikaite (CaCO3x6H2O). The columns are found in a shallow, narrow fjord named Ikka Fjord and their distribution clearly follows the outcrop of the Grønnedal-Íka complex. When meteoric water percolates through the highly fractured complex, a sodium carbonate solution of pH 10 is formed through hitherto unknown fluid-rock reactions. This basic solution seeps up through fractures at the bottom of Ikka Fjord and when mixed with seawater, the mineral ikaite is formed. As the seepage water has a lower density than seawater, there is an upwards flow that creates columns. What is peculiar about ikaite is its limited stability making it unstable above +6 °C. Isotopic studies of ikaite reveal a seawater origin for the Ca2+ ions, and the carbonatite being the most likely source for the CO32- ions. The carbonatite is mainly of søvite composition (CaCO3) with high contents of siderite and ankerite in certain areas. The nepheline syenites contain Na,K-rich minerals like nepheline, alkali-feldspar, aegirine-augite, katophorite and biotite. Nepheline is mainly replaced by muscovite, and aegirine-augite partly by chlorite, which could release sodium into solution. A dolerite dyke of unknown age prompted extensive mineralization of magnetite by activating hydrothermal fluid convection. The fluid interacted with the carbonatite, replacing siderite and ankerite by magnetite and later hematite. In a newly launched project at Stockholm University, we are trying to unravel the chemical reactions taking place inside the Grønnedal-Íka igneous complex leading to the formation of the sodium carbonate solution issuing in Ikka Fjord.

Changes in Serving Size, Calories, and Sodium Content in Processed Foods From 2009 to 2015

PubMed Central

Niederman, Sarah A.; Leonard, Elizabeth; Curtis, Christine J.

2018-01-01

Introduction Approximately 60% of the American diet comes from processed foods, which makes improving their nutritional quality important for Americans’ health. The objective of this study was to measure changes in serving sizes, calories, and sodium in top-selling processed foods that were on the market in 2009 and 2015. Methods We analyzed products in the top 80% of sales in the 54 processed food categories with consistent serving sizes and sales metrics that were on the market in both 2009 and 2015. Mean serving size, calories (per serving and density), sodium (per serving and density), and sales were calculated for 2,979 branded processed food products. For each stratification of calorie density and sodium density (decreased, increased, or did not change), we calculated the mean serving size, calorie density, sodium density, and sales for each year. Results From 2009 to 2015, we found decreases in serving size (−2.3%, P < .001), calories per serving (−2.0%, P < .001), calorie density (−1.1%, P < .001), sodium per serving (−7.6%, P < .001), and sodium density (−6.0%, P < .001). A decrease in calorie density did not correspond to an increase in sodium density or vice versa. A decline in sales was observed regardless of whether calorie density or sodium density decreased, increased, or did not change. Conclusion Reductions in calorie and sodium density occurred in tandem, suggesting that manufacturers reformulated for more than one health goal at the same time. Instead of unintended negative consequences of encouraging companies to reformulate for one nutrient, an overall net nutritional benefit occurred. PMID:29543584

Ion chromatographic methods for the detection of starch hydrolysis products in ruminal digesta.

PubMed

Barsuhn, K; Kotarski, S F

1991-06-21

Dionex high-performance ion chromatographic methods were evaluated for separation and quantitation of plant sugars and starch digestion products in the ruminal digesta of cattle. Mono- and disaccharides were eluted from a Dionex CarboPac PA1 column with sodium hydroxide used isocratically or as a pH gradient. Maltooligosaccharides which had a degree of polymerization (DP) less than 30 glucose residues were eluted in 60 min by a sodium hydroxide eluent containing a sodium acetate gradient. Carbohydrates were detected amperometrically. Responses were linear (r2 greater than 0.99) for glucose, disaccharides and maltooligosaccharides (DP less than 8). Precipitation and solid-phase extraction methods were evaluated for clean-up of samples of feedstuffs, ruminal contents, and bacterial culture fluids. Perchloric acid precipitation hydrolyzed sucrose but did not affect recoveries of cellobiose, isomaltose or maltose. Ethanol in concentrations of 79 and 86% precipitated maltooligosaccharides having chain lengths larger than 14 and 9 glucose residues, respectively. Maltooligosaccharide recoveries from solid-phase extraction columns varied with maltooligosaccharide size and column packing. Recoveries were greater than 94% for short chains (DP less than 6) eluted from phenyl-substituted columns and variable for all oligosaccharides eluted from C18 columns. Applications of these methods are presented and include: (1) detection of sugars in ruminant feed, (2) monitoring changes in ruminal sugars after feeding and (3) monitoring changes in extracellular sugars and oligosaccharides in the culture fluids of the ruminal bacterium, Bacteroides ruminicola.

Attempt to model laboratory-scale diffusion and retardation data.

PubMed

Hölttä, P; Siitari-Kauppi, M; Hakanen, M; Tukiainen, V

2001-02-01

Different approaches for measuring the interaction between radionuclides and rock matrix are needed to test the compatibility of experimental retardation parameters and transport models used in assessing the safety of the underground repositories for the spent nuclear fuel. In this work, the retardation of sodium, calcium and strontium was studied on mica gneiss, unaltered, moderately altered and strongly altered tonalite using dynamic fracture column method. In-diffusion of calcium into rock cubes was determined to predict retardation in columns. In-diffusion of calcium into moderately and strongly altered tonalite was interpreted using a numerical code FTRANS. The code was able to interprete in-diffusion of weakly sorbing calcium into the saturated porous matrix. Elution curves of calcium for the moderately and strongly altered tonalite fracture columns were explained adequately using FTRANS code and parameters obtained from in-diffusion calculations. In this paper, mass distribution ratio values of sodium, calcium and strontium for intact rock are compared to values, previously obtained for crushed rock from batch and crushed rock column experiments. Kd values obtained from fracture column experiments were one order of magnitude lower than Kd values from batch experiments.

Paleohydrology on Mars constrained by mass balance and mineralogy of pre-Amazonian sodium chloride lakes

NASA Astrophysics Data System (ADS)

Melwani Daswani, M.; Kite, E. S.

2017-09-01

Chloride-bearing deposits on Mars record high-elevation lakes during the waning stages of Mars' wet era (mid-Noachian to late Hesperian). The water source pathways, seasonality, salinity, depth, lifetime, and paleoclimatic drivers of these widespread lakes are all unknown. Here we combine reaction-transport modeling, orbital spectroscopy, and new volume estimates from high-resolution digital terrain models, in order to constrain the hydrologic boundary conditions for forming the chlorides. Considering a T = 0°C system, we find that (1) individual lakes were >100 m deep and lasted decades or longer; (2) if volcanic degassing was the source of chlorine, then the water-to-rock ratio or the total water volume were probably low, consistent with brief excursions above the melting point and/or arid climate; (3) if the chlorine source was igneous chlorapatite, then Cl-leaching events would require a (cumulative) time of >10 years at the melting point; and (4) Cl masses, divided by catchment area, give column densities 0.1-50 kg Cl/m2, and these column densities bracket the expected chlorapatite-Cl content for a seasonally warm active layer. Deep groundwater was not required. Taken together, our results are consistent with Mars having a usually cold, horizontally segregated hydrosphere by the time chlorides formed.

Precipitated Silica from Pumice and Carbon Dioxide Gas (Co2) in Bubble Column Reactor

NASA Astrophysics Data System (ADS)

Dewati, R.; Suprihatin, S.; Sumada, K.; Muljani, S.; Familya, M.; Ariani, S.

2018-01-01

Precipitated silica from silica and carbon dioxide gas has been studied successfully. The source of silica was obtained from pumice stone while precipitation process was carried out with carbon dioxide gas (CO2). The sodium silicate solution was obtained by extracting the silica from pumice stone with sodium hydroxide (NaOH) solution and heated to 100 °C for 1 h. The carbon dioxide gas is injected into the aqueous solution of sodium silicate in a bubble column reactor to form precipitated silica. m2/g. The results indicate that the products obtained are precipitate silica have surface area in the range of 100 - 227 m2/g, silica concentration more than 80%, white in appearance, and silica concentration reached 90% at pH 7.

Impact of NO2 horizontal heterogeneity on tropospheric NO2 vertical columns retrieved from satellite, multi-axis differential optical absorption spectroscopy, and in situ measurements

NASA Astrophysics Data System (ADS)

Mendolia, D.; D'Souza, R. J. C.; Evans, G. J.; Brook, J.

2013-01-01

Tropospheric NO2 vertical column densities were retrieved for the first time in Toronto, Canada using three methods of differing spatial scales. Remotely-sensed NO2 vertical column densities, retrieved from multi-axis differential optical absorption spectroscopy and satellite remote sensing, were evaluated by comparison with in situ vertical column densities derived using a pair of chemiluminescence monitors situated 0.01 and 0.5 km above ground level. The chemiluminescence measurements were corrected for the influence of NOz, which reduced the NO2 concentrations at 0.01 and 0.5 km by 8 ± 1% and 12 ± 1%, respectively. The average absolute decrease in the chemiluminescence NO2 measurement as a result of this correction was less than 1 ppb. Good correlation was observed between the remotely sensed and in situ NO2 vertical column densities (Pearson R ranging from 0.68 to 0.79), but the in situ vertical column densities were 27% to 55% greater than the remotely-sensed columns. These results indicate that NO2 horizontal heterogeneity strongly impacted the magnitude of the remotely-sensed columns. The in situ columns reflected an urban environment with major traffic sources, while the remotely-sensed NO2 vertical column densities were representative of the region, which included spatial heterogeneity introduced by residential neighbourhoods and Lake Ontario. Despite the difference in absolute values, the reasonable correlation between the vertical column densities determined by three distinct methods increased confidence in the validity of the values provided by each of the methods.

Distributed temperature sensor testing in liquid sodium

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gerardi, Craig; Bremer, Nathan; Lisowski, Darius

Rayleigh-backscatter-based distributed fiber optic sensors were immersed in sodium to obtain high-resolution liquid-sodium temperature measurements. Distributed temperature sensors (DTSs) functioned well up to 400°C in a liquid sodium environment. The DTSs measured sodium column temperature and the temperature of a complex geometrical pattern that leveraged the flexibility of fiber optics. A single Ø 360 lm OD sensor registered dozens of temperatures along a length of over one meter at 100 Hz. We also demonstrated the capability to use a single DTS to simultaneously detect thermal interfaces (e.g. sodium level) and measure temperature.

Understanding star formation in molecular clouds. I. Effects of line-of-sight contamination on the column density structure

NASA Astrophysics Data System (ADS)

Schneider, N.; Ossenkopf, V.; Csengeri, T.; Klessen, R. S.; Federrath, C.; Tremblin, P.; Girichidis, P.; Bontemps, S.; André, Ph.

2015-03-01

Column-density maps of molecular clouds are one of the most important observables in the context of molecular cloud- and star-formation (SF) studies. With the Herschel satellite it is now possible to precisely determine the column density from dust emission, which is the best tracer of the bulk of material in molecular clouds. However, line-of-sight (LOS) contamination from fore- or background clouds can lead to overestimating the dust emission of molecular clouds, in particular for distant clouds. This implies values that are too high for column density and mass, which can potentially lead to an incorrect physical interpretation of the column density probability distribution function (PDF). In this paper, we use observations and simulations to demonstrate how LOS contamination affects the PDF. We apply a first-order approximation (removing a constant level) to the molecular clouds of Auriga and Maddalena (low-mass star-forming), and Carina and NGC 3603 (both high-mass SF regions). In perfect agreement with the simulations, we find that the PDFs become broader, the peak shifts to lower column densities, and the power-law tail of the PDF for higher column densities flattens after correction. All corrected PDFs have a lognormal part for low column densities with a peak at Av ~ 2 mag, a deviation point (DP) from the lognormal at Av(DP) ~ 4-5 mag, and a power-law tail for higher column densities. Assuming an equivalent spherical density distribution ρ ∝ r- α, the slopes of the power-law tails correspond to αPDF = 1.8, 1.75, and 2.5 for Auriga, Carina, and NGC 3603. These numbers agree within the uncertainties with the values of α ≈ 1.5,1.8, and 2.5 determined from the slope γ (with α = 1-γ) obtained from the radial column density profiles (N ∝ rγ). While α ~ 1.5-2 is consistent with a structure dominated by collapse (local free-fall collapse of individual cores and clumps and global collapse), the higher value of α > 2 for NGC 3603 requires a physical process that leads to additional compression (e.g., expanding ionization fronts). From the small sample of our study, we find that clouds forming only low-mass stars and those also forming high-mass stars have slightly different values for their average column density (1.8 × 1021 cm-2 vs. 3.0 × 1021 cm-2), and they display differences in the overall column density structure. Massive clouds assemble more gas in smaller cloud volumes than low-mass SF ones. However, for both cloud types, the transition of the PDF from lognormal shape into power-law tail is found at the same column density (at Av ~ 4-5 mag). Low-mass and high-mass SF clouds then have the same low column density distribution, most likely dominated by supersonic turbulence. At higher column densities, collapse and external pressure can form the power-law tail. The relative importance of the twoprocesses can vary between clouds and thus lead to the observed differences in PDF and column density structure. Appendices are available in electronic form at http://www.aanda.orgHerschel maps as FITS files are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/575/A79

Simple, specific analysis of organophosphorus and carbamate pesticides in sediments using column extraction and gas chromatography

USGS Publications Warehouse

Belisle, A.A.; Swineford, D.M.

1988-01-01

A simple, specific procedure was developed for the analysis of organophosphorus and carbamate pesticides in sediment. The wet soil was mixed with anhydrous sodium sulfate to bind water and the residues were column extracted in acetone:methylene chloride (1:l,v/v). Coextracted water was removed by additional sodium sulfate packed below the sample mixture. The eluate was concentrated and analyzed directly by capillary gas chromatography using phosphorus and nitrogen specific detectors. Recoveries averaged 93 % for sediments extracted shortly after spiking, but decreased significantly as the samples aged.

Analysis of Mexico City urban air pollution using nitrogen dioxide column density measurements from UV/Visible spectroscopy

NASA Astrophysics Data System (ADS)

Garcia Payne, D. G.; Grutter, M.; Melamed, M. L.

2010-12-01

The differential optical absorption spectroscopy method (DOAS) was used to get column densities of nitrogen dioxide (NO2) from the analysis of zenith sky UV/visible spectra. Since the optical path length provides critical information in interpreting NO2 column densities, in conjunction with NO2 column densities, the oxygen dimer (O4) column density was retrieved to give insight into the optical path length. We report observations of year round NO2 and O4 column densities (from august 2009 to september 2010) from which the mean seasonal levels and the daily evolution, as well as the occurrence of elevated pollution episodes are examined. Surface nitric oxide (NO) and NO2 from the local monitoring network, as well as wind data and the vertical aerosol density from continuous Lidar measurements are used in the analysis to investigate specific events in the context of local emissions from vehicular traffic, photochemical production and transport from industrial emissions. The NO2 column density measurements will enhance the understanding Mexico City urban air pollution. Recent research has begun to unravel the complexity of the air pollution problem in Mexico City and its effects not only locally but on a regional and global scale as well.

[Determination of five synthetic sweeteners in wines using high performance liquid chromatography-tandem mass spectrometry].

PubMed

Ji, Chao; Feng, Feng; Chen, Zhengxing; Sun, Li; Chu, Xiaogang

2010-08-01

A high performance liquid chromatography-electrospray ionization tandem mass spectrometry (HPLC-ESI MS/MS) method for the determination of five synthetic sweeteners (acesulfame, sodium saccharin, sodium cyclamate, aspartame and neotame) in wines has been developed. The HPLC separation was carried out on an Ultimate C18 column (100 mm x 2.1 mm, 3 microm). Several parameters, including the composition and pH of the mobile phase, column temperature and the monitor ions, were optimized for improving the chromatographic performance and the sensitivity of determination. The results demonstrated that the separation can be completed in less than 5 min by gradient elution with 20 mmol/L ammonium formate and 0.1% (v/v) formic acid (pH 3.8) and methanol as the mobile phase. The column temperature was kept at 45 degrees C. When the analytes were detected by ESI -MS/MS under multiple reaction monitoring mode, the detection limits were 0.6, 5, 1, 0.8 and 0.2 microg/L for acesulfame, sodium saccharin, sodium cyclamate, aspartame and neotame, respectively. The average recoveries ranged from 87.2% to 103%. The relative standard deviations were not more than 1.2%. This method is rapid, accurate, highly sensitive and suitable for the quality control of low concentration of the synthetic sweeteners, which are illegally added to wines and other foods with complex matrices.

Developing procedures for the large-scale purification of human serum butyrylcholinesterase.

PubMed

Saxena, Ashima; Luo, Chunyuan; Doctor, Bhupendra P

2008-10-01

Human serum butyrylcholinesterase (Hu BChE) is the most viable candidate for the prophylactic treatment of organophosphate poisoning. A dose of 200 mg/70 kg is predicted to protect humans against 2x LD(50) of soman. Therefore, the aim of this study was to develop procedures for the purification of gram quantities of this enzyme from outdated human plasma or Cohn Fraction IV-4. The purification of Hu BChE was accomplished by batch adsorption on procainamide-Sepharose-CL-4B affinity gel followed by ion-exchange chromatography on a DEAE-Sepharose column. For the purification of enzyme from Cohn Fraction IV-4, it was resuspended in 25 mM sodium phosphate buffer, pH 8.0, and fat was removed by decantation, prior to batch adsorption on procainamide-Sepharose gel. In both cases, the procainamide gel was thoroughly washed with 25 mM sodium phosphate buffer, pH 8.0, containing 0.05 M NaCl, and the enzyme was eluted with the same buffer containing 0.1 M procainamide. The enzyme was dialyzed and the pH was adjusted to 4.0 before loading on the DEAE column equilibrated in sodium acetate buffer, pH 4.0. The column was thoroughly washed with 25 mM sodium phosphate buffer, pH 8.0 containing 0.05 M NaCl before elution with a gradient of 0.05-0.2M NaCl in the same buffer. The purity of the enzyme following these steps ranged from 20% to 40%. The purity of the enzyme increased to >90% by chromatography on an analytical procainamide affinity column. Results show that Cohn Fraction IV-4 is a much better source than plasma for the large-scale isolation of purified Hu BChE.

Determination of atomic sodium in coal combustion using laser-induced fluorescence

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sweeny, P.G.; Abrahamson, H.B.; Radonovich, L.J.

1987-01-01

A laser-induced fluorescence spectrometer (LIFS) was assembled and sodium atom densities produced from the aspiration of solutions and direct introduction of a lignite into a flame were determined from fluorescence measurements. The average flame volume observed was 0.4mm/sup 3/. This small volume allowed the measurement of sodium concentrations as a function of vertical and horizontal flame position. Temperature profiles of the flames employed were also obtained and compared with the sodium atom densities. The sodium atom densities calculated from the fluorescence measurements (N/sub tt/) are compared with the sodium atom densities calculated from thermodynamic considerations (N/sub tt/) and sodium concentrationsmore » derived from aspiration/introduction rates (N/sub ta/).« less

An Efficacy and Pharmacokinetic Evaluation of a Dose of Diazepam That Will Reduce the Incidence of Convulsions in Indian Rhesus Monkeys Pretreated with Pyridostigmine Bromide, Challenged with Soman, and Treated with Atropine and Pralidoxime Chloride with the Diazepam

DTIC Science & Technology

1990-12-01

benzophenone (Aldrich 23:985-2), tetrabutylammonium nitrate (Kodak 9664), sodium lauryl sulfate (dodecyl sulfide, sodium salt) (Aldrich 86-201-0), helium gas...phase buffer for the initial identity confirmation using a Supelco LC-I column by dissolving 6.0 g of sodium lauryl sulfate and 1.0 g of...water, glacial acetic acid (Baker Reagent’Grade), tetrabutylammonium chloride (Aldrich g8. percent), sodium lauryl sulfate (Aldrich 98 percent), sodium

Discovery of calcium in Mercury's atmosphere.

PubMed

Bida, T A; Killen, R M; Morgan, T H

2000-03-09

The composition and evolutionary history of Mercury's crust are not well determined. The planet as a whole has been predicted to have a refractory, anhydrous composition: rich in Ca, Al, Mg and Fe, but poor in Na, K, OH, and S. Its atmosphere is believed to be derived in large part from the surface materials. A combination of effects that include impact vaporization (from infalling material), volatile evaporation, photon-stimulated desorption and sputtering releases material from the surface to form the atmosphere. Sodium and potassium have already been observed in Mercury's atmosphere, with abundances that require a volatile-rich crust. The sodium probably results from photon-stimulated desorption, and has a temperature of 1,500 K (ref. 10). Here we report the discovery of calcium in the atmosphere near Mercury's poles. The column density is very low and the temperature is apparently very high (12,000 K). The localized distribution and high temperature, if confirmed, suggest that the atmospheric calcium may arise from surface sputtering by ions, which enter Mercury's auroral zone. The low abundance of atmospheric Ca may indicate that the regolith is rarefied in calcium.

Solubility and binding properties of PEGylated lysozyme derivatives with increasing molecular weight on hydrophobic-interaction chromatographic resins.

PubMed

Müller, Egbert; Josic, Djuro; Schröder, Tim; Moosmann, Anna

2010-07-09

Dynamic binding capacities and resolution of PEGylated lysozyme derivatives with varying molecular weights of poly (ethylene) glycol (PEG) with 5 kDa, 10 kDa and 30 kDa for HIC resins and columns are presented. To find the optimal range for the operating conditions, solubility studies were performed by high-throughput analyses in a 96-well plate format, and optimal salt concentrations and pH values were determined. The solubility of PEG-proteins was strongly influenced by the length of the PEG moiety. Large differences in the solubilities of PEGylated lysozymes in two different salts, ammonium sulfate and sodium chloride were found. Solubility of PEGylated lysozyme derivatives in ammonium sulfate decreases with increased length of attached PEG chains. In sodium chloride all PEGylated lysozyme derivatives are fully soluble in a concentration range between 0.1 mg protein/ml and 10 mg protein/ml. The binding capacities for PEGylated lysozyme to HIC resins are dependent on the salt type and molecular weight of the PEG polymer. In both salt solutions, ammonium sulfate and sodium chloride, the highest binding capacity of the resin was found for 5 kDa PEGylated lysozyme. For both native lysozyme and 30 kDa mono-PEGylated lysozyme the binding capacities were lower. In separation experiments on a TSKgel Butyl-NPR hydrophobic-interaction column with ammonium sulfate as mobile phase, the elution order was: native lysozyme, 5 kDa mono-PEGylated lysozyme and oligo-PEGylated lysozyme. This elution order was found to be reversed when sodium chloride was used. Furthermore, the resolution of the three mono-PEGylated forms was not possible with this column and ammonium sulfate as mobile phase. In 4 M sodium chloride a resolution of all PEGylated lysozyme forms was achieved. A tentative explanation for these phenomena can be the increased solvation of the PEG polymers in sodium chloride which changes the usual attractive hydrophobic forces in ammonium sulfate to more repulsive hydration forces in this hydrotrophic salt.

Longevity of granular iron in groundwater treatment processes: corrosion product development.

PubMed

Kohn, Tamar; Livi, Kenneth J T; Roberts, A Lynn; Vikesland, Peter J

2005-04-15

Permeable reactive barriers employing iron as a reactive surface have received extensive attention. A remaining issue, however, relates to their longevity. As an integral part of a long-term column study conducted to examine the influence of inorganic cosolutes on iron reactivity toward chlorinated solvents and nitroaromatic compounds, Master Builder iron grains were characterized via scanning and transmission electron microscopy, electron energy loss spectroscopy (EELS), micro-Raman spectroscopy, and X-ray diffraction. Prior to exposure to carbonate solutions, the iron grains were covered by a surface scale that consisted of fayalite (Fe2SiO4), wüstite (FeO), magnetite (Fe3O4), maghemite (gamma-Fe2O3), and graphite. After 1100 days of exposure to solutions containing carbonate, other inorganic solutes, and organic contaminants, the wüstite, fayalite, and graphite of the original scale partially dissolved, and magnetite and iron carbonate hydroxide (Fe3(OH)2.2CO3) precipitated on top of the scale. Raman results indicate the presence of green rust (e.g., [Fe4(2+)Fe2(3+)(OH)12]-[CO3 x 2H2O]) toward the column outlet after 308 days of operation, although this mineral phase disappears at longer operation times. Grains extracted from a column exposed to a high concentration (20 mM) of sodium bicarbonate were more extensively weathered than those from columns exposed to 2 mM sodium bicarbonate. An iron carbonate hydroxide layer up to 100 microm thick was observed. Even though EELS analysis of iron carbonate hydroxide indicates that this is a redox-active phase, the thickness of this layer is presumed responsible for the previously observed decline in the reactivity of this column relative to low-bicarbonate columns. A silica-containing feed resulted in reduced reactivity toward TCE. Grains from this column had a strong enrichment of silicon in the precipitates, although no distinct silica-containing mineral phases were identified. The substitution of 2 mM calcium carbonate for 2 mM sodium bicarbonate in the feed did not produce a measurable reactivity loss, asthe discrete calcium carbonate precipitates that formed in this system did not severely restrict access to the reactive surface.

Effects of remediation amendments on vadose zone microorganisms

DOE Office of Scientific and Technical Information (OSTI.GOV)

Miller, Hannah M.; Tilton, Fred A.

2012-08-10

Surfactant-based foam delivery technology has been studied to remediate Hanford 200 area deep vadose zone sediment. However, the surfactants and remediation amendments have an unknown effect on indigenous subsurface microorganisms. Microbial populations are important factors to consider in remediation efforts due to their potential to alter soil geochemistry. This project focuses on measuring microbial metabolic responses to remediation amendments in batch and column studies using Deep Vadose Zone Sediments. Initial studies of the microbes from Hanford 200 area deep vadose zone sediment showed surfactants sodium dodecyl sulfate (SDS) and cocamidopropyl betaine (CAPB) and remediation amendment calcium polysulfide (CPS) had nomore » affect on microbial growth using BiologTM Ecoplates. To move towards a more realistic field analog, soil columns were packed with Hanford 200 Area sediment. Once microbial growth in the column was verified by observing growth of the effluent solution on tryptic soy agar plates, remedial surfactants were injected into the columns, and the resulting metabolic diversity was measured. Results suggest surfactant sodium dodecyl sulfate (SDS) stimulates microbial growth. The soil columns were also visualized using X-ray microtomography to inspect soil packing and possibly probe for evidence of biofilms. Overall, BiologTM Ecoplates provide a rapid assay to predict effects of remediation amendments on Hanford 200 area deep vadose zone microorganisms.« less

Adsorptive removal of heavy metals from water using sodium titanate nanofibres loaded onto GAC in fixed-bed columns.

PubMed

Sounthararajah, D P; Loganathan, P; Kandasamy, J; Vigneswaran, S

2015-04-28

Heavy metals are serious pollutants in aquatic environments. A study was undertaken to remove Cu, Cd, Ni, Pb and Zn individually (single metal system) and together (mixed metals system) from water by adsorption onto a sodium titanate nanofibrous material. Langmuir adsorption capacities (mg/g) at 10(-3)M NaNO3 ionic strength in the single metal system were 60, 83, 115 and 149 for Ni, Zn, Cu, and Cd, respectively, at pH 6.5 and 250 for Pb at pH 4.0. In the mixed metals system they decreased at high metals concentrations. In column experiments with 4% titanate material and 96% granular activated carbon (w/w) mixture at pH 5.0, the metals breakthrough times and adsorption capacities (for both single and mixed metals systems) decreased in the order Pb>Cd, Cu>Zn>Ni within 266 bed volumes. The amounts adsorbed were up to 82 times higher depending on the metal in the granular activated carbon+titanate column than in the granular activated carbon column. The study showed that the titanate material has high potential for removing heavy metals from polluted water when used with granular activated carbon at a very low proportion in fixed-bed columns. Copyright © 2015 Elsevier B.V. All rights reserved.

The shapes of column density PDFs. The importance of the last closed contour

NASA Astrophysics Data System (ADS)

Alves, João; Lombardi, Marco; Lada, Charles J.

2017-10-01

The probability distribution function of column density (PDF) has become the tool of choice for cloud structure analysis and star formation studies. Its simplicity is attractive, and the PDF could offer access to cloud physical parameters otherwise difficult to measure, but there has been some confusion in the literature on the definition of its completeness limit and shape at the low column density end. In this letter we use the natural definition of the completeness limit of a column density PDF, the last closed column density contour inside a surveyed region, and apply it to a set of large-scale maps of nearby molecular clouds. We conclude that there is no observational evidence for log-normal PDFs in these objects. We find that all studied molecular clouds have PDFs well described by power laws, including the diffuse cloud Polaris. Our results call for a new physical interpretation of the shape of the column density PDFs. We find that the slope of a cloud PDF is invariant to distance but not to the spatial arrangement of cloud material, and as such it is still a useful tool for investigating cloud structure.

Comparison of tropospheric NO2 vertical columns in an urban environment using satellite, multi-axis differential optical absorption spectroscopy, and in situ measurements

NASA Astrophysics Data System (ADS)

Mendolia, D.; D'Souza, R. J. C.; Evans, G. J.; Brook, J.

2013-10-01

Tropospheric NO2 vertical column densities have been retrieved and compared for the first time in Toronto, Canada, using three methods of differing spatial scales. Remotely sensed NO2 vertical column densities, retrieved from multi-axis differential optical absorption spectroscopy and satellite remote sensing, were evaluated by comparison with in situ vertical column densities estimated using a pair of chemiluminescence monitors situated 0.01 and 0.5 km a.g.l. (above ground level). The chemiluminescence measurements were corrected for the influence of NOz, which reduced the NO2 concentrations at 0.01 and 0.5 km by an average of 8 ± 1% and 12 ± 1%, respectively. The average absolute decrease in the chemiluminescence NO2 measurement as a result of this correction was less than 1 ppb. The monthly averaged ratio of the NO2 concentration at 0.5 to 0.01 km varied seasonally, and exhibited a negative linear dependence on the monthly average temperature, with Pearson's R = 0.83. During the coldest month, February, this ratio was 0.52 ± 0.04, while during the warmest month, July, this ratio was 0.34 ± 0.04, illustrating that NO2 is not well mixed within 0.5 km above ground level. Good correlation was observed between the remotely sensed and in situ NO2 vertical column densities (Pearson's R value ranging from 0.72 to 0.81), but the in situ vertical column densities were 52 to 58% greater than the remotely sensed columns. These results indicate that NO2 horizontal heterogeneity strongly impacted the magnitude of the remotely sensed columns. The in situ columns reflected an urban environment with major traffic sources, while the remotely sensed NO2 vertical column densities were representative of the region, which included spatial heterogeneity introduced by residential neighbourhoods and Lake Ontario. Despite the difference in absolute values, the reasonable correlation between the vertical column densities determined by three distinct methods increased confidence in the validity of the values provided by each measurement technique.

Use of Sodium Dithionite as Part of a More Efficient Groundwater Restoration Method Following In-situ Recovery of Uranium at the Smith-Ranch Highland Site in Wyoming

NASA Astrophysics Data System (ADS)

Harris, R.; Reimus, P. W.; Ware, D.; Williams, K.; Chu, D.; Perkins, G.; Migdissov, A. A.; Bonwell, C.

2017-12-01

Uranium is primarily mined for nuclear power production using an aqueous extraction technique called in-situ recovery (ISR). ISR can pollute groundwater with residual uranium and other heavy metals. Reverse osmosis and groundwater sweep are currently used to restore groundwater after ISR mining, but are not permanent solutions. Sodium dithionite is being tested as part of a method to more permanently restore groundwater after ISR mining at the Smith-Ranch Highland site in Wyoming. Sodium dithionite is a chemical reductant that can reduce sediments that were oxidized during ISR. The reduced sediments can reduce soluble uranium (VI) in the groundwater to insoluble uranium (IV). Laboratory studies that use sodium dithionite to treat sediments and waters from the site may help predict how it will behave during a field deployment. An aqueous batch experiment showed that sodium dithionite reduced uranium in post-mined untreated groundwater from 38 ppm to less than 1 ppm after 1 day. A sediment reduction batch experiment showed that sodium dithionite-treated sediments were capable of reducing uranium in post-mined untreated groundwater from 38 ppm to 2 ppm after 7 days. One column experiment is showing post-mined sodium dithionite-treated sediments are capable of reducing uranium in post-mined groundwater for over 30 pore volumes past the initial injection. While these results are promising for field deployments of sodium dithionite, another column experiment with sodium dithionite-treated sediments containing uranium rich organic matter is showing net production of uranium instead of uranium uptake. Sodium dithionite appears to liberate uranium from the organic matter. Another sediment reduction experiment is being conducted to further investigate this hypothesis. These experiments are helping guide plans for field deployments of sodium dithionite at uranium ISR mining sites.

Interstellar C2, CH, and CN in translucent molecular clouds

NASA Technical Reports Server (NTRS)

Black, John H.; Van Dishoeck, Ewine F.

1989-01-01

Optical absorption-line techniques have been applied to the study of a number of translucent molecular clouds in which the total column densities are large enough that substantial molecular abundances can be maintained. Results are presented for a survey of absorption lines of interstellar C2, CH, and CN. Detections of CN through the A 2Pi-X 2Sigma(+) (1,O) and (2,O) bands of the red system are reported and compared with observations of the violet system for one line of sight. The population distributions in C2 provide diagnostic information on temperature and density. The measured column densities of the three species can be used to test details of the theory of molecule formation in clouds where photoprocesses still play a significant role. The C2 and CH column densities are strongly correlated with each other and probably also with the H2 column density. In contrast, the CN column densities are found to vary greatly from cloud to cloud. The observations are discussed with reference to detailed theoretical models.

Regression of Lingual Lymphatic Vessels in Sodium-restricted Mice.

PubMed

He, Lianying; McCluskey, Lynnette Phillips

2018-05-01

Lymphatic vessel networks can expand and regress, with consequences for interstitial fluid drainage and nutrient supply to tissues, inflammation, and tumor spread. A diet high in sodium stimulates hyperplasia of cutaneous lymphatic capillaries. We hypothesized that dietary sodium restriction would have the opposite effect, shrinking lymphatic capillaries in the tongue. Lingual lymphatic capillary density and size was significantly reduced in mice fed a low-sodium diet (0.03%) for 3 weeks compared with control-fed mice. Blood vessel density was unchanged. Despite lymphatic capillary shrinkage, lingual edema was not observed. The effect on lymphatic capillaries was reversible, as lymphatic density and size in the tongue were restored by 3 weeks on a control diet. Lymphatic hyperplasia induced by a high-sodium diet is dependent on infiltrating macrophages. However, lingual CD68+ macrophage density was unchanged by sodium deficiency, indicating that distinct mechanisms may mediate lymphatic regression. Further studies are needed to test whether dietary sodium restriction is an effective, non-invasive co-therapy for oral cancer.

Characterization of Virus Adsorption by Using DEAE-Sepharose and Octyl-Sepharose†

PubMed Central

Shields, Patricia A.; Farrah, Samuel R.

2002-01-01

Viruses were characterized by their adsorption to DEAE-Sepharose or by their elution from octyl-Sepharose by using buffered solutions of sodium chloride with different ionic strengths. Viruses whose adsorption to DEAE-Sepharose was reduced most rapidly by an increase in the sodium chloride concentration were considered to have the weakest electrostatic interactions with the solids; these viruses included MS2, E1, and φX174. Viruses whose adsorption to DEAE-Sepharose was reduced least rapidly were considered to have the strongest electrostatic interactions with the column; these viruses included P1, T4, T2, and E5. All of the viruses studied adsorbed to octyl-Sepharose in the presence of 4 M NaCl. Viruses that were eluted most rapidly following a decrease in the concentration of NaCl were considered to have the weakest hydrophobic interactions with the column; these viruses included φX174, CB4, and E1. Viruses that were eluted least rapidly from the columns after the NaCl concentration was decreased were considered to have the strongest hydrophobic interactions with the column; these viruses included f2, MS2, and E5. PMID:12147497

Characterization of virus adsorption by using DEAE-sepharose and octyl-sepharoser.

PubMed

Shields, Patricia A; Farrah, Samuel R

2002-08-01

Viruses were characterized by their adsorption to DEAE-Sepharose or by their elution from octyl-Sepharose by using buffered solutions of sodium chloride with different ionic strengths. Viruses whose adsorption to DEAE-Sepharose was reduced most rapidly by an increase in the sodium chloride concentration were considered to have the weakest electrostatic interactions with the solids; these viruses included MS2, E1, and phiX174. Viruses whose adsorption to DEAE-Sepharose was reduced least rapidly were considered to have the strongest electrostatic interactions with the column; these viruses included P1, T4, T2, and E5. All of the viruses studied adsorbed to octyl-Sepharose in the presence of 4 M NaCl. Viruses that were eluted most rapidly following a decrease in the concentration of NaCl were considered to have the weakest hydrophobic interactions with the column; these viruses included phiX174, CB4, and E1. Viruses that were eluted least rapidly from the columns after the NaCl concentration was decreased were considered to have the strongest hydrophobic interactions with the column; these viruses included f2, MS2, and E5.

Simulating the effect of high column density absorbers on the one-dimensional Lyman α forest flux power spectrum

NASA Astrophysics Data System (ADS)

Rogers, Keir K.; Bird, Simeon; Peiris, Hiranya V.; Pontzen, Andrew; Font-Ribera, Andreu; Leistedt, Boris

2018-03-01

We measure the effect of high column density absorbing systems of neutral hydrogen (H I) on the one-dimensional (1D) Lyman α forest flux power spectrum using cosmological hydrodynamical simulations from the Illustris project. High column density absorbers (which we define to be those with H I column densities N(H I) > 1.6 × 10^{17} atoms cm^{-2}) cause broadened absorption lines with characteristic damping wings. These damping wings bias the 1D Lyman α forest flux power spectrum by causing absorption in quasar spectra away from the location of the absorber itself. We investigate the effect of high column density absorbers on the Lyman α forest using hydrodynamical simulations for the first time. We provide templates as a function of column density and redshift, allowing the flexibility to accurately model residual contamination, i.e. if an analysis selectively clips out the largest damping wings. This flexibility will improve cosmological parameter estimation, for example, allowing more accurate measurement of the shape of the power spectrum, with implications for cosmological models containing massive neutrinos or a running of the spectral index. We provide fitting functions to reproduce these results so that they can be incorporated straightforwardly into a data analysis pipeline.

Pressure, temperature and density drops along supercritical fluid chromatography columns. I. Experimental results for neat carbon dioxide and columns packed with 3- and 5-micron particles.

PubMed

Poe, Donald P; Veit, Devon; Ranger, Megan; Kaczmarski, Krzysztof; Tarafder, Abhijit; Guiochon, Georges

2012-08-10

The pressure drop and temperature drop on columns packed with 3- and 5-micron particles were measured using neat CO(2) at a flow rate of 5 mL/min, at temperatures from 20°C to 100°C, and outlet pressures from 80 to 300 bar. The density drop was calculated based on the temperature and pressure at the column inlet and outlet. The columns were suspended in a circulating air bath either bare or covered with foam insulation. The results show that the pressure drop depends on the outlet pressure, the operating temperature, and the thermal environment. A temperature drop was observed for all conditions studied. The temperature drop was relatively small (less than 3°C) for combinations of low temperature and high pressure. Larger temperature drops and density drops occurred at higher temperatures and low to moderate pressures. Covering the column with thermal insulation resulted in larger temperature drops and corresponding smaller density drops. At 20°C the temperature drop was never more than a few degrees. The largest temperature drops occurred for both columns when insulated at 80°C and 80 bar, reaching a maximum value of 21°C for the 5-micron column, and 26°C for the 3-micron column. For an adiabatic column, the temperature drop depends on the pressure drop, the thermal expansion coefficient, and the density and the heat capacity of the mobile phase fluid, and can be described by a simple mathematical relationship. For a fixed operating temperature and outlet pressure, the temperature drop increases monotonically with the pressure drop. Copyright © 2012 Elsevier B.V. All rights reserved.

Pooled results from 5 validation studies of dietary self-report instruments using recovery biomarkers for potassium and sodium intake.

PubMed

Freedman, Laurence S; Commins, John M; Moler, James E; Willett, Walter; Tinker, Lesley F; Subar, Amy F; Spiegelman, Donna; Rhodes, Donna; Potischman, Nancy; Neuhouser, Marian L; Moshfegh, Alanna J; Kipnis, Victor; Arab, Lenore; Prentice, Ross L

2015-04-01

We pooled data from 5 large validation studies (1999-2009) of dietary self-report instruments that used recovery biomarkers as referents, to assess food frequency questionnaires (FFQs) and 24-hour recalls (24HRs). Here we report on total potassium and sodium intakes, their densities, and their ratio. Results were similar by sex but were heterogeneous across studies. For potassium, potassium density, sodium, sodium density, and sodium:potassium ratio, average correlation coefficients for the correlation of reported intake with true intake on the FFQs were 0.37, 0.47, 0.16, 0.32, and 0.49, respectively. For the same nutrients measured with a single 24HR, they were 0.47, 0.46, 0.32, 0.31, and 0.46, respectively, rising to 0.56, 0.53, 0.41, 0.38, and 0.60 for the average of three 24HRs. Average underreporting was 5%-6% with an FFQ and 0%-4% with a single 24HR for potassium but was 28%-39% and 4%-13%, respectively, for sodium. Higher body mass index was related to underreporting of sodium. Calibration equations for true intake that included personal characteristics provided improved prediction, except for sodium density. In summary, self-reports capture potassium intake quite well but sodium intake less well. Using densities improves the measurement of potassium and sodium on an FFQ. Sodium:potassium ratio is measured much better than sodium itself on both FFQs and 24HRs. Published by Oxford University Press on behalf of the Johns Hopkins Bloomberg School of Public Health 2015. This work is written by (a) US Government employee(s) and is in the public domain in the US.

Density Gradient Columns for Chemical Displays.

ERIC Educational Resources Information Center

Guenther, William B.

1986-01-01

Procedures for preparing density gradient columns for chemical displays are presented. They include displays illustrating acid-base reactions, metal ion equilibria, and liquid density. The lifetime of these metastable displays is surprising, some lasting for months in display cabinets. (JN)

Isoelectric focusing of red blood cells in a density gradient stabilized column

NASA Technical Reports Server (NTRS)

Smolka, A. J. K.; Miller, T. Y.

1980-01-01

The effects of Ficoll and cell application pH on red blood cell electrophoretic mobility and focusing pH were investigated by focusing cells in a density gradient stabilized column. Sample loading, cell dispersion, column conductivity, resolution of separation, and the effect of Ampholines were examined.

Cyclodextrins as a chiral mobile phase additive in nano-liquid chromatography: comparison of reversed-phase silica monolithic and particulate capillary columns.

PubMed

Rocco, Anna; Maruška, Audrius; Fanali, Salvatore

2012-03-01

Enantioseparations of racemic nonsteroidal anti-inflammatory drugs (naproxen, ibuprofen, ketoprofen, flurbiprofen, suprofen, indoprofen, cicloprofen, and carprofen) were performed by nano-liquid chromatography, employing achiral capillary columns and heptakis(2,3,6-tri-O-methyl)-β-cyclodextrin (TM-β-CD) or hydroxylpropyl-β-cyclodextrin (HP-β-CD) as a chiral mobile phase additive (CMPA). Working under the same experimental conditions (in terms of mobile phase and linear velocity), the performance of a RP-C18 monolithic column was compared with that of a RP-C18 packed column of the same dimensions (100 μm i.d. × 10 cm). Utilizing a mobile phase composed of 30% ACN (v/v) buffered with 50 mM sodium acetate at pH 3, and containing 30 mM TM-β-CD, the monolithic column provided faster analysis but lower resolution than the packed column. This behavior was ascribed to the high permeability of the monolithic column, as well as to its minor selectivity. HP-β-CD was chosen as an alternative to TM-β-CD. Employing the monolithic column, the effects of different parameters such as HP-β-CD concentration, mobile phase composition, and pH on the retention factor and the chiral resolution of the analytes were studied. For the most of the analytes, enantioresolution (which ranged from R(s) = 1.80 for naproxen to R(s) = 0.86 for flurbiprofen) was obtained with a mobile phase consisting of sodium acetate buffer (25 mM, pH 3), 10% MeOH, and 15 mM HP-β-CD. When the same experimental conditions were used with the packed column, no compound eluted within 1 h. Upon increasing the percentage of organic modifier to favor analyte elution, only suprofen eluted within 30 min, with an R(s) value of 1.14 (20% MeOH). Replacing MeOH with ACN resulted in a loss of enantioresolution, except for naproxen (R(s) = 0.89).

NiF2 Cathodes For Rechargeable Na Batteries

NASA Technical Reports Server (NTRS)

Bugga, Ratnakumar V.; Distefano, Salvador; Halpert, Gerald

1992-01-01

Use of NiF2 cathodes in medium-to-high-temperature rechargeable sodium batteries increases energy and power densities by 25 to 30 percent without detracting from potential advantage of safety this type of sodium battery offers over sodium batteries having sulfur cathodes. High-energy-density sodium batteries with metal fluoride cathodes used in electric vehicles and for leveling loads on powerlines.

The Effect of AGN Heating on the Low-redshift Lyα Forest

NASA Astrophysics Data System (ADS)

Gurvich, Alex; Burkhart, Blakesley; Bird, Simeon

2017-02-01

We investigate the effects of AGN heating and the ultraviolet background on the low-redshift Lyα forest column density distribution (CDD) using the Illustris simulation. We show that Illustris reproduces observations at z = 0.1 in the column density range {10}12.5{--}{10}13.5 cm-2, relevant for the “photon underproduction crisis.” We attribute this to the inclusion of AGN feedback, which changes the gas distribution so as to mimic the effect of extra photons, as well as the use of the Faucher-Giguère ultraviolet background, which is more ionizing at z = 0.1 than the Haardt & Madau background previously considered. We show that the difference between simulations run with smoothed particle hydrodynamics and simulations using a moving mesh is small in this column density range but can be more significant at larger column densities. We further consider the effect of supernova feedback, Voigt profile fitting, and finite resolution, all of which we show to have little influence on the CDD. Finally, we identify a discrepancy between our simulations and observations at column densities {10}14{--}{10}16 cm-2, where Illustris produces too few absorbers, which suggests the AGN feedback model should be further refined. Since the “photon underproduction crisis” primarily affects lower column density systems, we conclude that AGN feedback and standard ionizing background models can resolve the crisis.

Effects of Road Density and Road-Salt Application Practices on Sodium and Chloride Loads to the Scituate Reservoir, Rhode Island

NASA Astrophysics Data System (ADS)

Waldron, M. C.; Nimiroski, M.

2001-05-01

The Scituate Reservoir drainage basin is the drinking-water source area for two thirds of the population of Rhode Island. The effects of road density and road-salt-application practices on sodium and chloride concentrations in streams in the drainage basin were examined using concentration data collected at intervals of one to six months from January 1982 through June 2000 at 32 stream sites distributed throughout the basin. Median concentrations of sodium and chloride for individual streams during the period of data collection were related to 1995 road densities (road miles per square mile of subbasin) for roads maintained by the Rhode Island Department of Transportation (State-maintained roads) and for roads maintained by the four municipalities in the drainage basin (locally maintained roads). Nearly 60 percent of the variation in median stream sodium and chloride concentrations was accounted for by the variation in density of State-maintained roads (R2= 0.595, p < 0.0001). In contrast, no correlations could be identified between median concentrations of sodium and chloride in streams and the densities of locally maintained roads in the subbasins (R2 = 0.001, p = 0.8771). Also, there was no difference in the relations between median stream sodium concentrations and subbasin road densities for data collected before and after a 1990 State-mandated reduction in the rate of application of sodium during winter deicing of State-maintained roads. Analysis of data on sources of sodium and chloride in the Scituate Reservoir drainage basin during water year 2000 (October 1999 through September 2000) indicates that, while the lengths and densities of locally maintained roads were greater than those of State-maintained roads in most subbasins, the total amount of sodium applied during water year 2000 was nearly three times greater for State-maintained roads than for locally maintained roads. This would be expected, given that State-maintained roads carry more traffic at higher speeds than do locally maintained roads. In addition, the State-maintained roads tend to have more efficient drainage systems that quickly transport runoff directly to the streams. The lack of effect of the reduced sodium application rate on the relation between median stream sodium concentration and density of State-maintained roads may be due to inaccurate monitoring of application rates or to mobilization of sodium previously applied and stored in drainage basin soils. Thus, the amounts of sodium and chloride transported by tributary streams to the Scituate Reservoir depend more on the type of roads and other conditions in the tributary subbasins than on the actual length or density of the roads.

MAVEN/IUVS Apoapse Observations of the Martian FUV Dayglow

NASA Astrophysics Data System (ADS)

Correira, J.; Evans, J. S.; Stevens, M. H.; Schneider, N. M.; Stewart, I. F.; Deighan, J.; Jain, S.; Chaffin, M.; Crismani, M. M. J.; McClintock, B.; Holsclaw, G.; Lefèvre, F.; Lo, D.; Stiepen, A.; Clarke, J. T.; Mahaffy, P. R.; Bougher, S. W.; Bell, J. M.; Jakosky, B. M.

2015-12-01

We present FUV data (115 - 190 nm) from MAVEN/IUVS apoapse mode observations for the Oct 2014 through Feb 2015 time period. During apoapse mode the highly elliptical orbit of MAVEN allows for up to four apoapse disk images by IUVS per day. Maps of FUV feature intensities and intensity ratios as well as derived CO/CO2 and O/CO2 column density ratios will be shown. Column density ratios are derived from lookup tables created using the Atmospheric Ultraviolet Radiance Integrated Code [Strickland et al., 1999] in conjunction with observed intensity ratios. Column density ratios provide a measure of composition changes in the Martian atmosphere. Due to MAVEN's orbital geometry the observations from this time period focus on the southern hemisphere. The broad view provided by apoapse observations allows for the investigation of spatial and temporal variations (both long term and local time) of the atmospheric composition (via the column density ratios). IUVS FUV intensities and derived column density ratios will also be compared with model results from Mars Global Ionosphere/Thermosphere Model (MGITM) and the Mars Climate Database (MCD).

Preliminary Evaluation of the Control of Microbial Fouling by Laboratory and Pilot-Scale Air-Stripping Columns

DTIC Science & Technology

1985-03-01

used to remove trichloroethylene (TCE) from contaminated well water. 7 MATERIALS Chemicals: Trichloroethylene (Aldrich chemical, Milwaukee, WI), sodium ...Cleveland, OH), sodium hydrcxide (J.T. Baker, Phillipsburg, NJ), potassium dichloroisocyanurate (Dorex Inc., Frankfort, IL), potassium iodide starch...NJ). Media and Reagents: Plate count agar (Difco Laboratories, Detroit, MI), lauryl tryptose broth (Difco Laboratories, Detroit, MI), motility medium

Observations of circumstellar carbon monoxide and evidence for multiple ejections in red giants

NASA Technical Reports Server (NTRS)

Bernat, A. P.

1981-01-01

Observations of the fundamental 4.6 micron band of CO in nine red giants are presented. A common feature is multiple absorption lines which are identified as products of separate components or shells. Column densities are derived; the relative values should be free of the uncertainties inherent in determining the absolute scale. These column densities are well fitted by single excitation temperatures for each absorption component; these excitation temperatures are identified with the local kinetic temperatures. There is no correlation of CO column density with either gas or dust column density nor of the expansion velocity of the component with its distance from the star. The evidence is reviewed, and it is concluded that mass loss from red giants is most likely episodic in nature.

Advanced intermediate temperature sodium-nickel chloride batteries with ultra-high energy density.

PubMed

Li, Guosheng; Lu, Xiaochuan; Kim, Jin Y; Meinhardt, Kerry D; Chang, Hee Jung; Canfield, Nathan L; Sprenkle, Vincent L

2016-02-11

Sodium-metal halide batteries have been considered as one of the more attractive technologies for stationary electrical energy storage, however, they are not used for broader applications despite their relatively well-known redox system. One of the roadblocks hindering market penetration is the high-operating temperature. Here we demonstrate that planar sodium-nickel chloride batteries can be operated at an intermediate temperature of 190 °C with ultra-high energy density. A specific energy density of 350 Wh kg(-1), higher than that of conventional tubular sodium-nickel chloride batteries (280 °C), is obtained for planar sodium-nickel chloride batteries operated at 190 °C over a long-term cell test (1,000 cycles), and it attributed to the slower particle growth of the cathode materials at the lower operating temperature. Results reported here demonstrate that planar sodium-nickel chloride batteries operated at an intermediate temperature could greatly benefit this traditional energy storage technology by improving battery energy density, cycle life and reducing material costs.

Advanced intermediate temperature sodium-nickel chloride batteries with ultra-high energy density

NASA Astrophysics Data System (ADS)

Li, Guosheng; Lu, Xiaochuan; Kim, Jin Y.; Meinhardt, Kerry D.; Chang, Hee Jung; Canfield, Nathan L.; Sprenkle, Vincent L.

2016-02-01

Sodium-metal halide batteries have been considered as one of the more attractive technologies for stationary electrical energy storage, however, they are not used for broader applications despite their relatively well-known redox system. One of the roadblocks hindering market penetration is the high-operating temperature. Here we demonstrate that planar sodium-nickel chloride batteries can be operated at an intermediate temperature of 190 °C with ultra-high energy density. A specific energy density of 350 Wh kg-1, higher than that of conventional tubular sodium-nickel chloride batteries (280 °C), is obtained for planar sodium-nickel chloride batteries operated at 190 °C over a long-term cell test (1,000 cycles), and it attributed to the slower particle growth of the cathode materials at the lower operating temperature. Results reported here demonstrate that planar sodium-nickel chloride batteries operated at an intermediate temperature could greatly benefit this traditional energy storage technology by improving battery energy density, cycle life and reducing material costs.

Americium, Cesium, and Plutonium Colloid-Facilitated Transport in a Groundwater/Bentonite/Fracture Fill Material System: Column Experiments and Model Results

NASA Astrophysics Data System (ADS)

Dittrich, T. M.; Boukhalfa, H.; Reimus, P. W.

2014-12-01

The objective of this study was to investigate and quantify the effects of desorption kinetics and colloid transport on radionuclides with different sorption affinities. We focused on quantifying transport mechanisms important for upscaling in time and distance. This will help determine the long-term fate and transport of radionuclides to aid in risk assessments. We selected a fractured/weathered granodiorite at the Grimsel Test Site (GTS) in Switzerland as a model crystalline rock repository system because the system has been thoroughly studied and field experiments involving radionuclides have already been conducted. Working on this system provides a unique opportunity to compare lab experiments with field-scale observations. Weathered fracture fill material (FFM) and bentonite used as backfill at the GTS were characterized (e.g., BET, SEM/EDS, QXRD), and batch and breakthrough column experiments were conducted. Solutions were prepared in synthetic groundwaters that matched the natural water chemistry. FFM samples were crushed, rinsed, sieved (150-355 μm), and equilibrated with synthetic groundwater. Bentonite was crushed, sodium-saturated, equilibrated with synthetic groundwater, and settled to yield a stable suspension. Suspensions were equilibrated with Am, Cs, or Pu. All experiments were conducted with Teflon®materials to limit sorption to system components. After radionuclide/colloid injections reached stability, radionuclide-free solutions were injected to observe the desorption and release behavior. Aliquots of effluent were measured for pH, colloid concentration, and total and dissolved radionuclides. Unanalyzed effluent from the first column was then injected through a second column of fresh material. The process was repeated for a third column and the results of all three breakthrough curves were modeled with a multi-site/multi-rate MATLAB code to elucidate the sorption rate coefficients and binding site densities of the bentonite colloids and fracture fill material. Nearly 50% of the sorbed Am was exchanged from the colloids to the fracture filling material in each of the three columns; whereas, less Cs and Pu was desorbed with each pass through a new column. Using a two-site kinetic model allowed for interrogation of desorption rates and dominant transport parameters.

Controlling the Laser Guide Star power density distribution at Sodium layer by combining Pre-correction and Beam-shaping

NASA Astrophysics Data System (ADS)

Huang, Jian; Wei, Kai; Jin, Kai; Li, Min; Zhang, YuDong

2018-06-01

The Sodium laser guide star (LGS) plays a key role in modern astronomical Adaptive Optics Systems (AOSs). The spot size and photon return of the Sodium LGS depend strongly on the laser power density distribution at the Sodium layer and thus affect the performance of the AOS. The power density distribution is degraded by turbulence in the uplink path, launch system aberrations, the beam quality of the laser, and so forth. Even without any aberrations, the TE00 Gaussian type is still not the optimal power density distribution to obtain the best balance between the measurement error and temporal error. To optimize and control the LGS power density distribution at the Sodium layer to an expected distribution type, a method that combines pre-correction and beam-shaping is proposed. A typical result shows that under strong turbulence (Fried parameter (r0) of 5 cm) and for a quasi-continuous wave Sodium laser (power (P) of 15 W), in the best case, our method can effectively optimize the distribution from the Gaussian type to the "top-hat" type and enhance the photon return flux of the Sodium LGS; at the same time, the total error of the AOS is decreased by 36% with our technique for a high power laser and poor seeing.

Study of axial mixing, holdup and slip velocity of dispersed phase in a pulsed sieve plate extraction column using radiotracer technique.

PubMed

Ghiyas Ud Din; Imran Rafiq Chughtai; Hameed Inayat, Mansoor; Hussain Khan, Iqbal

2009-01-01

Axial mixing, holdup and slip velocity of dispersed phase which are parameters of fundamental importance in the design and operation of liquid-liquid extraction pulsed sieve plate columns have been investigated. Experiments for residence time distribution (RTD) analysis have been carried out for a range of pulsation frequency and amplitude in a liquid-liquid extraction pulsed sieve plate column with water as dispersed and kerosene as continuous phase using radiotracer technique. The column was operated in emulsion region and (99m)Tc in the form of sodium pertechnetate eluted from a (99)Mo/(99m)Tc generator was used to trace the dispersed phase. Axial dispersed plug flow model with open-open boundary condition and two points measurement method was used to simulate the hydrodynamics of dispersed phase. It has been observed that the axial mixing and holdup of dispersed phase increases with increase in pulsation frequency and amplitude until a maximum value is achieved while slip velocity decreases with increase in pulsation frequency and amplitude until it approaches a minimum value. Short lived and low energy radiotracer (99m)Tc in the form of sodium pertechnetate was found to be a good water tracer to study the hydrodynamics of a liquid-liquid extraction pulsed sieve plate column operating with two immiscible liquids, water and kerosene. Axial dispersed plug flow model with open-open boundary condition was found to be a suitable model to describe the hydrodynamics of dispersed phase in the pulsed sieve plate extraction column.

Remotely operable compact instruments for measuring atmospheric CO2 and CH4 column densities at surface monitoring sites

NASA Astrophysics Data System (ADS)

Kobayashi, N.; Inoue, G.; Kawasaki, M.; Yoshioka, H.; Minomura, M.; Murata, I.; Nagahama, T.; Matsumi, Y.; Tanaka, T.; Morino, I.; Ibuki, T.

2010-08-01

Remotely operable compact instruments for measuring atmospheric CO2 and CH4 column densities were developed in two independent systems: one utilizing a grating-based desktop optical spectrum analyzer (OSA) with a resolution enough to resolve rotational lines of CO2 and CH4 in the regions of 1565-1585 and 1674-1682 nm, respectively; the other is an application of an optical fiber Fabry-Perot interferometer (FFPI) to obtain the CO2 column density. Direct sunlight was collimated via a small telescope installed on a portable sun tracker and then transmitted through an optical fiber into the OSA or the FFPI for optical analysis. The near infrared spectra of the OSA were retrieved by a least squares spectral fitting algorithm. The CO2 and CH4 column densities deduced were in excellent agreement with those measured by a Fourier transform spectrometer with high resolution. The rovibronic lines in the wavelength region of 1570-1575 nm were analyzed by the FFPI. The I0 and I values in the Beer-Lambert law equation to obtain CO2 column density were deduced by modulating temperature of the FFPI, which offered column CO2 with the statistical error less than 0.2% for six hours measurement.

Understanding star formation in molecular clouds. II. Signatures of gravitational collapse of IRDCs

NASA Astrophysics Data System (ADS)

Schneider, N.; Csengeri, T.; Klessen, R. S.; Tremblin, P.; Ossenkopf, V.; Peretto, N.; Simon, R.; Bontemps, S.; Federrath, C.

2015-06-01

We analyse column density and temperature maps derived from Herschel dust continuum observations of a sample of prominent, massive infrared dark clouds (IRDCs) i.e. G11.11-0.12, G18.82-0.28, G28.37+0.07, and G28.53-0.25. We disentangle the velocity structure of the clouds using 13CO 1→0 and 12CO 3→2 data, showing that these IRDCs are the densest regions in massive giant molecular clouds (GMCs) and not isolated features. The probability distribution function (PDF) of column densities for all clouds have a power-law distribution over all (high) column densities, regardless of the evolutionary stage of the cloud: G11.11-0.12, G18.82-0.28, and G28.37+0.07 contain (proto)-stars, while G28.53-0.25 shows no signs of star formation. This is in contrast to the purely log-normal PDFs reported for near and/or mid-IR extinction maps. We only find a log-normal distribution for lower column densities, if we perform PDFs of the column density maps of the whole GMC in which the IRDCs are embedded. By comparing the PDF slope and the radial column density profile of three of our clouds, we attribute the power law to the effect of large-scale gravitational collapse and to local free-fall collapse of pre- and protostellar cores for the highest column densities. A significant impact on the cloud properties from radiative feedback is unlikely because the clouds are mostly devoid of star formation. Independent from the PDF analysis, we find infall signatures in the spectral profiles of 12CO for G28.37+0.07 and G11.11-0.12, supporting the scenario of gravitational collapse. Our results are in line with earlier interpretations that see massive IRDCs as the densest regions within GMCs, which may be the progenitors of massive stars or clusters. At least some of the IRDCs are probably the same features as ridges (high column density regions with N> 1023 cm-2 over small areas), which were defined for nearby IR-bright GMCs. Because IRDCs are only confined to the densest (gravity dominated) cloud regions, the PDF constructed from this kind of a clipped image does not represent the (turbulence dominated) low column density regime of the cloud. The column density maps (FITS files) are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/578/A29

Copper Chloride Cathode For Liquid-Sodium Cell

NASA Technical Reports Server (NTRS)

Bugga, Ratnakumar V.; Distefano, Salvador; Nagasubramanian, Ganesan; Bankston, Clyde P.

1990-01-01

Rechargeable liquid-sodium cell with copper chloride cathode offers substantial increase in energy density over cells made with other cathode materials. Unit has theoretical maximum energy density of 1135 W.h/kg. Generates electricity by electrochemical reaction of molten sodium and solid copper chloride immersed in molten electrolyte, sodium tetrachloroaluminate at temperature of equal to or greater than 200 degrees C. Wall of alumina tube separates molten electrolyte from molten sodium anode. Copper chloride cathode embedded in pores of sintered nickel cylinder or directly sintered.

Tetragonal Chicken Egg White Lysozyme Solubility in Sodium Chloride Solutions

NASA Technical Reports Server (NTRS)

Forsythe, Elizabeth L.; Judge, Russell A.; Pusey, Marc L.

1998-01-01

The solubility of chicken egg white lysozyme, crystallized in the tetragonal form was measured in sodium chloride solutions from 1.6 to 30.7 C, using a miniature column solubility apparatus. Sodium chloride solution concentrations ranged from 1 to 7% (w/v). The solutions were buffered with 0.1 M sodium acetate buffer with the solubility being measured at pH values in 0.2 pH unit increments in the range pH 4.0 to 5.4, with data also included at pH 4.5. Lysozyme solubility was found to increase with increases in temperature and decreasing salt concentration. Solution pH has a varied and unpredictable effect on solubility.

Advanced rechargeable sodium batteries with novel cathodes

NASA Technical Reports Server (NTRS)

Distefano, S.; Ratnakumar, B. V.; Bankston, C. P.

1989-01-01

Various high energy density rechargeable batteries are being considered for future space applications. Of these, the sodium sulfur battery is one of the leading candidates. The primary advantage is the high energy density (760 Wh/kg theoretical). Energy densities in excess of 180 Wh/kg have been realized in practical batteries. More recently, cathodes other than sulfur are being evaluated. Researchers at JPL are evaluating various new cathode materials for use in high energy density sodium batteries for advanced space applications. The approach is to carry out basic electrochemical studies of these materials in a sodium cell configuration in order to understand their fundamental behaviors. Thus far studies have focused on alternate metal chlorides such as CuCl2 and organic cathode materials such as tetracyanoethylene (TCNE).

Advanced rechargeable sodium batteries with novel cathodes

NASA Technical Reports Server (NTRS)

Di Stefano, S.; Ratnakumar, B. V.; Bankston, C. P.

1990-01-01

Various high energy density rechargeable batteries are being considered for future space applications. Of these, the sodium-sulfur battery is one of the leading candidates. The primary advantage is the high energy density (760 W h/kg theoretical). Energy densities in excess of 180 W h/kg have been realized in practical batteries. More recently, cathodes other than sulfur are being evaluated. Various new cathode materials are presently being evaluated for use in high energy density sodium batteries for advanced space applications. The approach is to carry out basic electrochemical studies of these materials in a sodium cell configuration in order to understand their fundamental behaviors. Thus far, the studies have focussed on alternative metal chlorides such as CuCl2 and organic cathode materials such as TCNE.

The effect of chemical treatment on reduction of aflatoxins and ochratoxin A in black and white pepper during washing.

PubMed

Jalili, M; Jinap, S; Son, R

2011-04-01

The effect of 18 different chemicals, which included acidic compounds (sulfuric acid, chloridric acid, phosphoric acid, benzoic acid, citric acid, acetic acid), alkaline compounds (ammonia, sodium bicarbonate, sodium hydroxide, potassium hydroxide, calcium hydroxide), salts (acetate ammonium, sodium bisulfite, sodium hydrosulfite, sodium chloride, sodium sulfate) and oxidising agents (hydrogen peroxide, sodium hypochlorite), on the reduction of aflatoxins B(1), B(2), G(1) and G(2) and ochratoxin A (OTA) was investigated in black and white pepper. OTA and aflatoxins were determined using HPLC after immunoaffinity column clean-up. Almost all of the applied chemicals showed a significant degree of reduction on mycotoxins (p < 0.05). The lowest and highest reduction of aflatoxin B(1), which is the most dangerous aflatoxin, was 20.5% ± 2.7% using benzoic acid and 54.5% ± 2.7% using sodium hydroxide. There was no significant difference between black and white peppers (p < 0.05).

Influence of Surface Sorption Processes on Spectral Induced Polarization Evaluated Using in-Situ Monitoring of a Na-22 Tracer

NASA Astrophysics Data System (ADS)

Hao, N.; Moysey, S. M.; Powell, B. A.; Ntarlagiannis, D.

2014-12-01

Spectral Induced Polarization (SIP) has been used to monitor subsurface biogeochemical processes in a variety of lab and field studies. However, there are several competing mechanisms that have been proposed to explain the SIP effect. This work targets the influence of ion sorption to mineral surfaces as a controlling factor on SIP utilizing a pH dependent surface adsorption experiment. In this experiment we use silica gel as an idealized medium where the number of available sites for cation sorption, which in this case is limited to Na+ and H+ ions, is influenced by changes in pH via protonation/deprotonation of silanol groups. The experiment uses 22Na as an in situ tracer as the radioactive decay of this nuclide can be continuously and non-invasively monitored using sensors placed outside of a column. The experiment was conducted by continuously pumping a 0.01M NaCl solution spiked with of 1μCi/L 22Na in to the column under three pH conditions (pH 5.0, 6.0 and 8.0). In the experiment, we observed an increasing number of gamma counts caused by the accumulation of sorbed 22Na in the column as we increased the pH from 5.0 to 6.5, and finally to 8.0. Simultaneously, we observed a linearly correlated (R2 = 0.99) rise in the imaginary conductivity response of the SIP measurements. Using the triple layer electrochemical polarization model for grain polarization to simulate our experimental SIP responses, we found that the estimated surface site density is within a factor of two of that estimated from the mass accumulation of sodium. Since the accumulation of sodium on the silica gel surface is responsible for both the increase in gamma radiation and the change in the electrical response, these observations support the theory that mobile ions in the Stern layer of mineral surfaces provide the primary control on SIP signals in silicate materials.

Comparison of neptunium sorption results using batch and column techniques

DOE Office of Scientific and Technical Information (OSTI.GOV)

Triay, I.R.; Furlano, A.C.; Weaver, S.C.

1996-08-01

We used crushed-rock columns to study the sorption retardation of neptunium by zeolitic, devitrified, and vitric tuffs typical of those at the site of the potential high-level nuclear waste repository at Yucca Mountain, Nevada. We used two sodium bicarbonate waters (groundwater from Well J-13 at the site and water prepared to simulate groundwater from Well UE-25p No. 1) under oxidizing conditions. It was found that values of the sorption distribution coefficient, Kd, obtained from these column experiments under flowing conditions, regardless of the water or the water velocity used, agreed well with those obtained earlier from batch sorption experiments undermore » static conditions. The batch sorption distribution coefficient can be used to predict the arrival time for neptunium eluted through the columns. On the other hand, the elution curves showed dispersivity, which implies that neptunium sorption in these tuffs may be nonlinear, irreversible, or noninstantaneous. As a result, use of a batch sorption distribution coefficient to calculate neptunium transport through Yucca Mountain tuffs would yield conservative values for neptunium release from the site. We also noted that neptunium (present as the anionic neptunyl carbonate complex) never eluted prior to tritiated water, which implies that charge exclusion does not appear to exclude neptunium from the tuff pores. The column experiments corroborated the trends observed in batch sorption experiments: neptunium sorption onto devitrified and vitric tuffs is minimal and sorption onto zeolitic tuffs decreases as the amount of sodium and bicarbonate/carbonate in the water increases.« less

Hydrodynamic flow in capillary-channel fiber columns for liquid chromatography.

PubMed

Stanelle, Rayman D; Sander, Lane C; Marcus, R Kenneth

2005-12-23

The flow characteristics of capillary-channel polymer (C-CP) fiber liquid chromatographic (LC) columns have been investigated. The C-CP fibers are manufactured with eight longitudinal grooves (capillary channels) extending the length of the fibers. Three C-CP fiber examples were studied, with fiber dimensions ranging from approximately 35 microm to 65 microm, and capillary-channel dimensions ranging from approximately 6 microm to 35 microm. The influence of fiber packing density and column inner diameter on peak asymmetry, peak width, and run-to-run reproducibility have been studied for stainless steel LC columns packed with polyester (PET) and polypropylene (PP) C-CP fibers. The van Deemter A-term was evaluated as a function of fiber packing density (approximately 0.3 g/cm(3)-0.75 g/cm(3)) for columns of 4.6 mm inner diameter (i.d.) and at constant packing densities for 1.5 mm, 3.2 mm, 4.6 mm, and 7.7 mm i.d. columns. Although column diameter had little influence on the eluting peak widths, peak asymmetry increased with increasing column diameter. The A-terms for the C-CP fiber packed columns are somewhat larger than current commercial, microparticulate-packed columns, and means for improvement are discussed. Applications in the area of protein (macromolecule) separations appear the most promising at this stage of the system development.

Sodium-tetravalent sulfur molten chloroaluminate cell

DOEpatents

Mamantov, Gleb

1985-04-02

A sodium-tetravalent sulfur molten chloroaluminate cell with a .beta."-alumina sodium ion conductor having a S-Al mole ratio of above about 0.15 in an acidic molten chloroaluminate cathode composition is disclosed. The cathode composition has an AlCl.sub.3 -NaCl mole percent ratio of above about 70-30 at theoretical full charge. The cell provides high energy densities at low temperatures and provides high energy densities and high power densities at moderate temperatures.

A Validated Stability-Indicating RP-UPLC Method for Simultaneous Determination of Desloratadine and Sodium Benzoate in Oral Liquid Pharmaceutical Formulations.

PubMed

Kumar, Navneet; Sangeetha, Dhanaraj; Reddy, Pingili Sunil; Prakash, Lakkireddy

2012-01-01

A novel, sensitive and selective stability-indicating gradient reverse phase ultra performance liquid chromatographic method was developed and validated for the quantitative determination of desloratadine and sodium benzoate in pharmaceutical oral liquid formulation. The chromatographic separation was achieved on Acquity BEH C8 (100 mm × 2.1 mm) 1.7 μm column by using mobile phase containing a gradient mixture of solvent A (0.05 M KH(2)PO(4) and 0.07 M triethylamine, pH 3.0) and B (50:25:25 v/v/v mixture of acetonitrile, methanol and water) at flow rate of 0.4 mL/min. Column temperature was maintained at 40°C and detection was carried out at a wavelength of 272 nm. The described method shows excellent linearity over a range of 0.254 μg/mL to 76.194 μg/mL for desloratadine and 1.006 μg/mL to 301.67 μg/mL for sodium benzoate. The correlation coefficient for desloratadine and sodium benzoate was more than 0.999. To establish stability-indicating capability of the method, drug product was subjected to the stress conditions of acid, base, oxidative, hydrolytic, thermal and photolytic degradation. The degradation products were well resolved from desloratadine and sodium benzoate. The developed method was validated as per international ICH guidelines with respect to specificity, linearity, LOD, LOQ, accuracy, precision and robustness.

Validation of a stability-indicating hydrophilic interaction liquid chromatographic method for the quantitative determination of vitamin k3 (menadione sodium bisulfite) in injectable solution formulation.

PubMed

Ghanem, Mashhour M; Abu-Lafi, Saleh A; Hallak, Hussein O

2013-01-01

A simple, specific, accurate, and stability-indicating method was developed and validated for the quantitative determination of menadione sodium bisulfite in the injectable solution formulation. The method is based on zwitterionic hydrophilic interaction liquid chromatography (ZIC-HILIC) coupled with a photodiode array detector. The desired separation was achieved on the ZIC-HILIC column (250 mm × 4.6 mm, 5 μm) at 25°C temperature. The optimized mobile phase consisted of an isocratic solvent mixture of 200mM ammonium acetate (NH4AC) solution and acetonitrile (ACN) (20:80; v/v) pH-adjusted to 5.7 by glacial acetic acid. The mobile phase was fixed at 0.5 ml/min and the analytes were monitored at 261 nm using a photodiode array detector. The effects of the chromatographic conditions on the peak retention, peak USP tailing factor, and column efficiency were systematically optimized. Forced degradation experiments were carried out by exposing menadione sodium bisulfite standard and the injectable solution formulation to thermal, photolytic, oxidative, and acid-base hydrolytic stress conditions. The degradation products were well-resolved from the main peak and the excipients, thus proving that the method is a reliable, stability-indicating tool. The method was validated as per ICH and USP guidelines (USP34/NF29) and found to be adequate for the routine quantitative estimation of menadione sodium bisulfite in commercially available menadione sodium bisulfite injectable solution dosage forms.

Adsorption and leaching behaviour of bispyribac-sodium in soils.

PubMed

Singh, Neera; Singh, S B

2015-01-01

Adsorption-desorption of the herbicide bispyribac-sodium was studied in four Indian soil types. Bispyribac-sodium was poorly adsorbed in the four soils and adsorption decreased with an increase in the herbicide concentration in solution. Freundlich adsorption coefficient (Kf) values for bispyribac-sodium ranged between 0.37 and 0.87. Slope (1/n) values varied from 0.2 to 0.31 suggesting that bispyribac-sodium adsorption was highly dependent on its initial concentration in solution. Bispyribac-sodium adsorption showed a positive correlation with soil pH (r = 0.809) and clay content (r = 0.699) while no correlation was observed with the organic carbon (r = 0.063) content. Sorbed herbicide was completely desorbed during a single desorption step suggesting that the herbicide was bound by weak adsorptive forces. Leaching studies of herbicide in soil 1 packed column indicated complete loss of soil applied herbicide under a simulated rainfall equivalent to 162 mm.

3D free-standing nitrogen-doped reduced graphene oxide aerogel as anode material for sodium ion batteries with enhanced sodium storage.

PubMed

Zhang, Jiao; Li, Chuanqi; Peng, Zhikun; Liu, Yushan; Zhang, Jianmin; Liu, Zhongyi; Li, Dan

2017-07-07

Sodium ion batteries have drawn extensive attentions for large-scale energy storage to replace lithium ion batteries primarily due to the natural abundance of sodium resource and low cost, but their energy density and electrochemical performance are hindered by the sluggish diffusion kinetics of sodium ion. Herein, free-standing nitrogen-doped graphene aerogel has been fabricated via hydrothermal reaction as the potential anode material for sodium ion batteries. The three dimensional porous network structure of the graphene aerogel provides sufficient interstitial space for sodium ion accommodation, allowing fast and reversible ion intercalation/de-intercalation. The nitrogen doping could introduce defects on the graphene sheets, making the feasible transport of large-sized sodium ion. Benefiting from the effective structure and nitrogen doping, the obtained material demonstrates high reversible capacities, good cycling performance (287.9 mA h g -1 after 200 cycles at a current density of 100 mA g -1 ), especially superior rate capability (151.9 mA h g -1 at a high current density of 5 A g -1 ).

Did the April 14-24 storms impact the mesopause region sodium density, temperature and wind over Fort Collins, CO (41N, 105W)

NASA Astrophysics Data System (ADS)

Arnold, K. S.; She, C.; Yuan, T.; Williams, B. P.; Krueger, D. A.

2002-12-01

The April 14-24 storms is under intense study to determine, among other things, its MLTI response. The change in sodium density, neutral temperature and winds in the mesopause region (80-110km) is a useful signature to look for. The Colorado State Sodium Lidar happened to have made nocturnal observations of sodium density, neutral temperature and zonal wind in April, 8th, 12th, 13th, 18th, and 22nd through 25th. We hope to determine and report if statistically meaningful changes in these important quantities had indeed occurred.

Separation of carbon nanotubes into chirally enriched fractions

DOEpatents

Doorn, Stephen K [Los Alamos, NM; Niyogi, Sandip [Los Alamos, NM

2012-04-10

A mixture of single-walled carbon nanotubes ("SWNTs") is separated into fractions of enriched chirality by preparing an aqueous suspension of a mixture of SWNTs and a surfactant, injecting a portion of the suspension on a column of separation medium having a density gradient, and centrifuging the column. In some embodiments, salt is added prior to centrifugation. In other embodiments, the centrifugation is performed at a temperature below room temperature. Fractions separate as colored bands in the column. The diameter of the separated SWNTs decreases with increasing density along the gradient of the column. The colored bands can be withdrawn separately from the column.

Interstellar C IV and Si IV column densities toward early-type stars

NASA Technical Reports Server (NTRS)

Bruhweiler, F. C.; Kondo, Y.; Mccluskey, G. E.

1980-01-01

Equivalent widths and deduced column densities of Si IV and C IV are examined for 18 early-type close binaries, and physical processes responsible for the origin of these ions in the interstellar medium are investigated. The available C IV/Si IV column density ratios typically lie within a narrow range from 0.8 to 4.5, and there is evidence that the column density of C IV is higher than that of N V along most lines of sight, suggesting that C IV is not formed in the same hot region as O VI. In addition, the existence of regions with a narrowly defined new temperature range around 50,000 deg K is indicated. The detection of the semitorrid gas of Bruhweiler, Kondo, and McCluskey (1978, 1979) is substantiated, and the relation of this gas to the observations of coronal gas in the galactic halo is discussed.

Turnover of Phosphatidic Acid and Sodium Extrusion from Mammalian Erythrocytes

PubMed Central

Kirschner, Leonard B.; Barker, Jennifer

1964-01-01

Phosphatidic acid (PA) from swine and beef RBCs was isolated by chromatography on silicic acid columns. It comprised about 1 per cent of the total lipid phosphate in RBCs, but was eluted nearly pure from columns. An uncharacterized inositide accounted for 5 to 10 per cent of the phosphate in the PA-containing fraction. When cells were incubated with HP32O4 =, the fraction containing PA became more radioactive than any of the other fractions obtained. However, analysis of the labeled material by paper chromatography showed that most of the P32 was in the inositide, not in PA. With the assumption of kinetic homogeneity for cellular PA, compartmental analysis of the kinetics of tracer incorporation showed that PA turnover is 3 to 4 orders of magnitude too slow to account for sodium extrusion by these cells. PMID:14192545

Highly-ionized metals as probes of the circumburst gas in the natal regions of gamma-ray bursts

NASA Astrophysics Data System (ADS)

Heintz, K. E.; Watson, D.; Jakobsson, P.; Fynbo, J. P. U.; Bolmer, J.; Arabsalmani, M.; Cano, Z.; Covino, S.; D'Elia, V.; Gomboc, A.; Japelj, J.; Kaper, L.; Krogager, J.-K.; Pugliese, G.; Sánchez-Ramírez, R.; Selsing, J.; Sparre, M.; Tanvir, N. R.; Thöne, C. C.; de Ugarte Postigo, A.; Vergani, S. D.

2018-06-01

We present here a survey of high-ionization absorption lines in the afterglow spectra of long-duration gamma-ray bursts (GRBs) obtained with the VLT/X-shooter spectrograph. Our main goal is to investigate the circumburst medium in the natal regions of GRBs. Our primary focus is on the N V λλ 1238,1242 line transitions, but we also discuss other high-ionization lines such as O VI, C IV and Si IV. We find no correlation between the column density of N V and the neutral gas properties such as metallicity, H I column density and dust depletion, however the relative velocity of N V, typically a blueshift with respect to the neutral gas, is found to be correlated with the column density of H I. This may be explained if the N V gas is part of an H II region hosting the GRB, where the region's expansion is confined by dense, neutral gas in the GRB's host galaxy. We find tentative evidence (at 2σ significance) that the X-ray derived column density, NH, X, may be correlated with the column density of N V, which would indicate that both measurements are sensitive to the column density of the gas located in the vicinity of the GRB. We investigate the scenario where N V (and also O VI) is produced by recombination after the corresponding atoms have been stripped entirely of their electrons by the initial prompt emission, in contrast to previous models where highly-ionized gas is produced by photoionization from the GRB afterglow.

Determination of the line shapes of atomic nitrogen resonance lines by magnetic scans

NASA Technical Reports Server (NTRS)

Lawrence, G. M.; Stone, E. J.; Kley, D.

1976-01-01

A technique is given for calibrating an atomic nitrogen resonance lamp for use in determining column densities of atoms in specific states. A discharge lamp emitting the NI multiplets at 1200 A and 1493 A is studied by obtaining absorption by atoms in a magnetic field (0-2.5 T). This magnetic scanning technique enables the determination of the absorbing atom column density, and an empirical curve of growth is obtained because the atomic f-value is known. Thus, the calibrated lamp can be used in the determination of atomic column densities.

Large-Scale Structure of the Molecular Gas in Taurus Revealed by High Spatial Dynamic Range Spectral Line Mapping

NASA Technical Reports Server (NTRS)

Goldsmith, Paul F.

2008-01-01

Viewgraph topics include: optical image of Taurus; dust extinction in IR has provided a new tool for probing cloud morphology; observations of the gas can contribute critical information on gas temperature, gas column density and distribution, mass, and kinematics; the Taurus molecular cloud complex; average spectra in each mask region; mas 2 data; dealing with mask 1 data; behavior of mask 1 pixels; distribution of CO column densities; conversion to H2 column density; variable CO/H2 ratio with values much less than 10(exp -4) at low N indicated by UV results; histogram of N(H2) distribution; H2 column density distribution in Taurus; cumulative distribution of mass and area; lower CO fractional abundance in mask 0 and 1 regions greatly increases mass determined in the analysis; masses determined with variable X(CO) and including diffuse regions agrees well with the found from L(CO); distribution of young stars as a function of molecular column density; star formation efficiency; star formation rate and gas depletion; and enlarged images of some of the regions with numerous young stars. Additional slides examine the origin of the Taurus molecular cloud, evolution from HI gas, kinematics as a clue to its origin, and its relationship to star formation.

Antibody-immobilized column for quick cell separation based on cell rolling.

PubMed

Mahara, Atsushi; Yamaoka, Tetsuji

2010-01-01

Cell separation using methodological standards that ensure high purity is a very important step in cell transplantation for regenerative medicine and for stem cell research. A separation protocol using magnetic beads has been widely used for cell separation to isolate negative and positive cells. However, not only the surface marker pattern, e.g., negative or positive, but also the density of a cell depends on its developmental stage and differentiation ability. Rapid and label-free separation procedures based on surface marker density are the focus of our interest. In this study, we have successfully developed an antiCD34 antibody-immobilized cell-rolling column, that can separate cells depending on the CD34 density of the cell surfaces. Various conditions for the cell-rolling column were optimized including graft copolymerization, and adjustment of the column tilt angle, and medium flow rate. Using CD34-positive and -negative cell lines, the cell separation potential of the column was established. We observed a difference in the rolling velocities between CD34-positive and CD34-negative cells on antibody-immobilized microfluidic device. Cell separation was achieved by tilting the surface 20 degrees and the increasing medium flow. Surface marker characteristics of the isolated cells in each fraction were analyzed using a cell-sorting system, and it was found that populations containing high density of CD34 were eluted in the delayed fractions. These results demonstrate that cells with a given surface marker density can be continuously separated using the cell rolling column.

C+/H2 gas in star-forming clouds and galaxies

NASA Astrophysics Data System (ADS)

Nordon, Raanan; Sternberg, Amiel

2016-11-01

We present analytic theory for the total column density of singly ionized carbon (C+) in the optically thick photon dominated regions (PDRs) of far-UV irradiated (star-forming) molecular clouds. We derive a simple formula for the C+ column as a function of the cloud (hydrogen) density, the far-UV field intensity, and metallicity, encompassing the wide range of galaxy conditions. When assuming the typical relation between UV and density in the cold neutral medium, the C+ column becomes a function of the metallicity alone. We verify our analysis with detailed numerical PDR models. For optically thick gas, most of the C+ column is mixed with hydrogen that is primarily molecular (H2), and this `C+/H2' gas layer accounts for almost all of the `CO-dark' molecular gas in PDRs. The C+/H2 column density is limited by dust shielding and is inversely proportional to the metallicity down to ˜0.1 solar. At lower metallicities, H2 line blocking dominates and the C+/H2 column saturates. Applying our theory to CO surveys in low-redshift spirals, we estimate the fraction of C+/H2 gas out of the total molecular gas to be typically ˜0.4. At redshifts 1 < z < 3 in massive disc galaxies the C+/H2 gas represents a very small fraction of the total molecular gas (≲ 0.16). This small fraction at high redshifts is due to the high gas surface densities when compared to local galaxies.

VizieR Online Data Catalog: Gamma Ray Bursts detected by Swift (2004-2015) (Buchner+, 2017)

NASA Astrophysics Data System (ADS)

Buchner, J.; Schulze, S.; Bauer, F.

2016-04-01

Gamma Ray Bursts (GRB) typically show intrinsic LOS column densities of 1021-23cm2. We performed a thorough statistical analysis of all available X-ray spectra of Swift-detected GRBs. In the associated paper we use sub-samples to analyse the population properties of LGRB and concluded that the obscuration is due to large-scale gas inside the GRB host galaxy, due to the shape of the column density distribution and its correlation with host stellar mass. This catalogue presents X-ray spectral analysis of all Swift-detected GRBs. It includes information about the GRB (ID, Swift Trigger ID, duration, RA/Dec in J2000, galactic coordinates, Milky Way column density). Those properties are taken from the http://www.swift.ac.uk/ and http://gcn.gsfc.nasa.gov/ websites. We removed prompt emission and flares, leaving only a certain time interval for spectral extraction. We use two models to analyse X-ray spectra: TBABS and SPHERE. Both include updated abundances and cross-sections as compared to previous works. The latter includes the effects of Compton-scattering and FeKa fluorescence relevant at high column densities. Columns list the posterior mean, standard deviation, 10% and 90% quantiles. Note that the column densities are converted to hydrogen assuming local ISM abundances, but are derived primarily from photo-electric absorption of e.g. Fe and O, and therefore primarily measure metal gas. (2 data files).

Density response of the mesospheric sodium layer to gravity wave perturbations

NASA Technical Reports Server (NTRS)

Shelton, J. D.; Gardner, C. S.; Sechrist, C. F., Jr.

1980-01-01

Lidar observations of the mesospheric sodium layer often reveal wavelike features moving through the layer. It is often assumed that these features are a layer density response to gravity waves. Chiu and Ching (1978) described the approximate form of the linear response of atmospheric layers to gravity waves. In this paper, their results are used to predict the response of the sodium layer to gravity waves. These simulations are compared with experimental observations and a good correlation is found between the two. Because of the thickness of the sodium layer and the density gradients found in it, a linear model of the layer response is not always adequate to describe gravity wave-sodium layer interactions. Inclusion of nonlinearities in the layer response is briefly discussed. Experimental data is seen to contain features consistent with the predicted nonlinearities.

Effects of dazomet, metam sodium, and oxamyl on Longidorus populations and loblolly pine seedline production

Treesearch

Stephen W. Fraedrich; L. David Dwinell

2005-01-01

Dazomet, metam sodium, and oxamyl were evaluated for nematode control and production of loblolly pine seedlings in a field infested by a Longidorus sp. Fumigation with dazomet or metam sodium reduced population densities of longidorus to nondetectable levels early in the growing season but population densities subsequently increases to levels found in untreated control...

Evolution of HI from Z=5 to the present

NASA Technical Reports Server (NTRS)

Storrie-Lombardi, L. J.

2002-01-01

Studies of damped Lya systems provide us with a good measure of the evolution of the HI column density distribution function and the contribution to the comoving mass density in neutral gas out to redshifts of z = 5 . The column density distribution function at high redshift steepens for the highest column density HI absorbers, though the contribution to the comoving mass density of neutral gas remains fiat from 2 < z < 5 . Results from studies at z < 2 are finding substantial numbers of damped absorbers identified from MgII absorption, compared to previous blind surveys. These results indicate that the contribution to the comoving mass density in neutral gas may be constant from z 0 to z 5. Details of recent work in the redshift range z < 2 work is covered elsewhere in this volume (see D. Nestor). We review here recent results for the redshift range 2 < z < 5.

Use of Chelex-100 for selectively removing Y-90 from its parent Sr-90

DOEpatents

Huntley, Mark W.

1996-01-01

A method for selectively removing yttrium-90 from its parent strontium-90 contained in an environmental sample includes loading the sample onto a column containing a chelating ion-exchange resin capable of retaining yttrium-90; washing the column with a solution capable of removing strontium, calcium, and other contaminants from the yttrium-90 fraction retained on the column; removing excess acetate salts from the column; eluting yttrium-90 solution from the column and adjusting the pH of this solution to about 2.7; filtering the yttrium-90 solution and weighing this solution for gravimetric yield; and, counting the yttrium-90 containing solution with a radiological counter for a time sufficient to achieve the statistical accuracy desired. It is preferred that the chelating ion-exchange resin is a bidente ligand having the chemical name iminodiacetic acid mounted on a divinyl benzene substrate, converted from sodium form to ammonia form.

Use of Chelex-100 for selectively removing Y-90 from its parent Sr-90

DOEpatents

Huntley, M.W.

1996-02-27

A method for selectively removing yttrium-90 from its parent strontium-90 contained in an environmental sample includes loading the sample onto a column containing a chelating ion-exchange resin capable of retaining yttrium-90; washing the column with a solution capable of removing strontium, calcium, and other contaminants from the yttrium-90 fraction retained on the column; removing excess acetate salts from the column; eluting yttrium-90 solution from the column and adjusting the pH of this solution to about 2.7; filtering the yttrium-90 solution and weighing this solution for gravimetric yield; and, counting the yttrium-90 containing solution with a radiological counter for a time sufficient to achieve the statistical accuracy desired. It is preferred that the chelating ion-exchange resin is a ligand having the chemical name iminodiacetic acid mounted on a divinyl benzene substrate, converted from sodium form to ammonia form.

Concentration, composition and apolipoprotein B species of very low density lipoprotein subfractions from normolipidemic and hypertriglyceridemic humans.

PubMed

Bittolo Bon, G; Cazzolato, G; Zago, S; Avogaro, P

1985-01-01

Lipoproteins in the d less than 1.006 g/ml density range obtained form 13 healthy normolipidemic subjects and from 15 patients affected by primary endogenous hypertriglyceridemia after 14-h fasting were subfractionated by filtration in Biogel A-15 M columns. The mass values and chemical composition of very low density lipoprotein (VLDL) subfractions 1 and 2 thus obtained were studied. In each subfraction the behavior of apolipoprotein B (Apo B) was tested by sodium dodecyl-sulfate polyacrylamide gel electrophoresis. VLDL2 was higher and richer in cholesterol and proteins than VLDL1, while the percentage content of triglycerides was lower. In hypertriglyceridemic patients both VLDL1 and VLDL2 were higher than in normolipidemic subjects, the difference being particularly evident for VLDL1. In both VLDL1 and VLDL2 of nearly all the subjects studied the presence in electrophoretic gels of a large Apo B-100 band and of a minor Apo B-48 band with the appropriate mobility of lymph chylomicrons was detected. The Apo B-100/Apo B-48 ratio was about 6 in VLDL1 and 24 in VLDL2. A trend of a reduced Apo B-100/Apo B-48 ratio was observed in VLDL1 of hypertriglyceridemic patients.

Model calculation of Cr dissolution behavior of ODS ferritic steel in high-temperature flowing sodium environment

NASA Astrophysics Data System (ADS)

Ohtsuka, Satoshi; Tanno, Takashi; Oka, Hiroshi; Yano, Yasuhide; Kato, Shoichi; Furukawa, Tomohiro; Kaito, Takeji

2018-07-01

A calculation model was constructed to systematically study the effects of environmental conditions (i.e. Cr concentration in sodium, test temperature, axial temperature gradient of fuel pin, and sodium flow velocity) on Cr dissolution behavior. Chromium dissolution was largely influenced by small changes in Cr concentration (i.e. chemical potential of Cr) in liquid sodium in the model calculation. Chromium concentration in sodium coolant, therefore, should be recognized as a critical parameter for the prediction and management of Cr dissolution behavior in the sodium-cooled fast reactor (SFR) core. Because the fuel column length showed no impact on dissolution behavior in the model calculation, no significant downstream effects possibly take place in the SFR fuel cladding tube due to the much shorter length compared with sodium loops in the SFR plant and the large axial temperature gradient. The calculated profile of Cr concentration along the wall-thickness direction was consistent with that measured in BOR-60 irradiation test where Cr concentration in inlet sodium bulk flow was set at 0.07 wt ppm in the calculation.

Sodium Reduction in US Households' Packaged Food and Beverage Purchases, 2000 to 2014.

PubMed

Poti, Jennifer M; Dunford, Elizabeth K; Popkin, Barry M

2017-07-01

Initiatives to reduce sodium in packaged foods have been launched in the United States, yet corresponding changes in the amount of sodium that US households obtain from packaged foods have not been evaluated, to our knowledge. To assess 15-year changes in the amount of sodium that US households acquire from packaged food purchases, the sodium content of purchases, and the proportion of households that have purchases with optimal sodium density. Longitudinal study of US households in the 2000 to 2014 Nielsen Homescan Consumer Panel, a population-based sample of households that used barcode scanners to record all packaged foods purchased throughout the year. Time-varying brand- and product-specific nutrition information was used for 1 490 141 products. Sociodemographic-adjusted changes in mean sodium per capita (mg/d) and sodium content (mg/100 g), overall and for top food group sources of sodium, and the proportion of households that have total purchases with sodium density of 1.1 mg/kcal or less. In a nationwide sample of 172 042 US households (754 608 year-level observations), the amount of sodium that households acquired from packaged food and beverage purchases decreased significantly between 2000 and 2014 by 396 mg/d (95% CI, -407 to -385 mg/d) per capita. The sodium content of households' packaged food purchases decreased significantly during this 15-year period by 49 mg/100 g (95% CI, -50 to -48 mg/100 g), a 12.0% decline; decreases began in 2005 and continued through 2014. Moreover, the sodium content of households' purchases decreased significantly for all top food sources of sodium between 2000 and 2014, including declines of more than 100 mg/100 g for condiments, sauces, and dips (-114 mg/100 g; 95% CI, -117 to -111 mg/100 g) and salty snacks (-142 mg/100 g; 95% CI, -144 to -141 mg/100 g). However, in all years, less than 2% of US households had packaged food and beverage purchases with sodium density of 1.1 mg/kcal or less. In this nationwide study, significant reductions in sodium from packaged food purchases were achieved in the past 15 years. Nonetheless, most US households had food and beverage purchases with excessive sodium density. Findings suggest that more concerted sodium reduction efforts are needed in the United States.

Sinking velocities of phytoplankton measured on a stable density gradient by laser scanning

PubMed Central

Walsby, Anthony E; Holland, Daryl P

2005-01-01

Two particular difficulties in measuring the sinking velocities of phytoplankton cells are preventing convection within the sedimenting medium and determining the changing depth of the cells. These problems are overcome by using a density-stabilized sedimentation column scanned by a laser. For freshwater species, a suspension of phytoplankton is layered over a vertical density gradient of Percoll solution; as the cells sink down the column their relative concentration is measured by the forward scattering of light from a laser beam that repeatedly scans up and down the column. The Percoll gradient stabilizes the column, preventing vertical mixing by convection, radiation or perturbation of density by the descending cells. Measurements were made on suspensions of 15 μm polystyrene microspheres with a density of 1050 kg m−3; the mean velocity was 6.28 μm s−1, within 1.5% of that calculated by the Stokes equation, 6.36 μm s−1. Measurements made on the filamentous cyanobacterium Planktothrix rubescens gave mean velocities within the theoretical range of values based on the range of size, shape, orientation and density of the particles in a modified Stokes equation. Measurements on marine phytoplankton may require density gradients prepared with other substances. PMID:16849271

HIDEEP - an extragalactic blind survey for very low column-density neutral hydrogen

NASA Astrophysics Data System (ADS)

Minchin, R. F.; Disney, M. J.; Boyce, P. J.; de Blok, W. J. G.; Parker, Q. A.; Banks, G. D.; Freeman, K. C.; Garcia, D. A.; Gibson, B. K.; Grossi, M.; Haynes, R. F.; Knezek, P. M.; Lang, R. H.; Malin, D. F.; Price, R. M.; Stewart, I. M.; Wright, A. E.

2003-12-01

We have carried out an extremely long integration time (9000 s beam-1) 21-cm blind survey of 60 deg2 in Centaurus using the Parkes multibeam system. We find that the noise continues to fall as throughout, enabling us to reach an HI column-density limit of 4.2 × 1018 cm-2 for galaxies with a velocity width of 200 km s-1 in the central 32 deg2 region, making this the deepest survey to date in terms of column density sensitivity. The HI data are complemented by very deep optical observations from digital stacking of multi-exposure UK Schmidt Telescope R-band films, which reach an isophotal level of 26.5 R mag arcsec-2 (~=27.5 B mag arcsec-2). 173 HI sources have been found, 96 of which have been uniquely identified with optical counterparts in the overlap area. There is not a single source without an optical counterpart. Although we have not measured the column densities directly, we have inferred them from the optical sizes of their counterparts. All appear to have a column density of NHI= 1020.65+/-0.38. This is at least an order of magnitude above our sensitivity limit, with a scatter only marginally larger than the errors on NHI. This needs explaining. If confirmed it means that HI surveys will only find low surface brightness (LSB) galaxies with high MHI/LB. Gas-rich LSB galaxies with lower HI mass to light ratios do not exist. The paucity of low column-density galaxies also implies that no significant population will be missed by the all-sky HI surveys being carried out at Parkes and Jodrell Bank.

Fine structure of Galactic foreground ISM towards high-redshift AGN - utilizing Herschel PACS and SPIRE data

NASA Astrophysics Data System (ADS)

Perger, K.; Pinter, S.; Frey, S.; Tóth, L. V.

2018-05-01

One of the most certain ways to determine star formation rate in galaxies is based on far infrared (FIR) measurements. To decide the origin of the observed FIR emission, subtracting the Galactic foreground is a crucial step. We utilized Herschel photometric data to determine the hydrogen column densities in three galactic latitude regions, at b = 27°, 50° and -80°. We applied a pixel-by-pixel fit to the spectral energy distribution (SED) for the images aquired from parallel PACS-SPIRE observations in all three sky areas. We determined the column densities with resolutions 45'' and 6', and compared the results with values estimated from the IRAS dust maps. Column densities at 27° and 50° galactic latitudes determined from the Herschel data are in a good agreement with the literature values. However, at the highest galactic latitude we found that the column densities from the Herschel data exceed those derived from the IRAS dust map.

A hybrid approach for treating fluorided water and biogeophysical monitoring of treatment processes

NASA Astrophysics Data System (ADS)

Singh, K. P.

2016-12-01

A laboratory experiment has been conducted for investigating the possibility of development of novel techniques for treating fluoride contamination and monitoring of physico-chemical alterations caused by biogeochemical processes in the media. In the present study, high adsorption capacity and ion-exchange property of natural zeolites have been utilized in treating fluoride contamination. The preset goals are achieved by designing and constructing experimental setup consisting of three columns, first one is filled with 450 ppm fluorided water prepared by dissolving sodium fluoride in deionized water, the second is filled with zeolite and fluorided water, and the third is filled with zeolite, fluorided water, sodium lactate and the bacterial seed. The first and the second columns were poisoned with sodium azide for preventing the growth of microorganisms. The self-potential (SP) signals associated with physico-chemical alterations in natural zeolite induced by biogeochemical processes are measured by using Cu-CuSO4 gel electrodes. Liquid-phase analysis of samples from column two and three show the reduced concentrations of fluoride and aluminum and it indicates the possibility of precipitation of insoluble aluminum fluoride. This is further confirmed by the presence of fluoride and aluminum in the solid samples as detected by energy dispersive X-ray analysis. The distinct SP of the order of -50 mV and 200 mV have been associated with biostimulated fluoride remediation and geochemical fluoride remediation processes respectively. Thus, there is a possibility of non-invasive monitoring of fluoride remediation processes driven by both microbes and chemical processes. It is found that after thirty-day nitrate and sulfate is introduced in column two due chemical interaction between water and natural zeolite. Furthermore, this study demonstrates that a hybrid approach, a combination of ion exchange and adsorption properties of natural zeolite and the bioremediation is more effective and less expensive than the chemical methodologies.

Free standing Cu2Te, new anode material for sodium-ion battery

NASA Astrophysics Data System (ADS)

Sarkar, Ananta; Mallick, Md. Mofasser; Panda, Manas Ranjan; Vitta, Satish; Mitra, Sagar

2018-05-01

Sodium-ion battery is the most popular alternative to lithium-ion energy storage system due to its low cost and huge abundant resources throughout the world. Although recent literature showed cathode materials for sodium ion battery performs almost equivalent to lithium-ion counterpart but the anode of this sodium-ion battery is in premature state. Here, we introduced free-standing copper telluride (Cu2Te), a new anode materials for sodium-ion battery. For making the electrode we did not use any conductive carbon or current collector which increase the volumetric density as well as reduce the cost of the cell. This metallic Cu2Te alloy exhibited a high reversible capacity of ˜275 mAh g-1 at 50 mA g-1 current density and ˜200 mAh g-1 at higher current density of 100 mA g-1, operating between 0.1 to 2.0 V.

Advanced rechargeable sodium batteries with novel cathodes

NASA Technical Reports Server (NTRS)

Distefano, S.; Ratnakumar, B. V.; Bankston, C. P.

1989-01-01

Various high energy density rechargeable batteries are being considered for future space applications. Of these, the sodium-sulfur battery is one of the leading candidates. The primary advantage is the high energy density (760 Wh/kg theoretical). Energy densities in excess of 180 Wh/kg were realized in practical batteries. Other technological advantages include its chemical simplicity, absence of self-discharge, and long cycle life possibility. More recently, other high temperature sodium batteries have come into the spotlight. These systems can be described as follow: Na/Beta Double Prime-Al2O3/NaAlCl4/Metal Dichloride Sodium/metal dichloride systems are colloquially known as the zebra system and are currently being developed for traction and load leveling applications. The sodium-metal dichloride systems appear to offer many of the same advantages of the Na/S system, especially in terms of energy density and chemical simplicity. The metal dichloride systems offer increased safety and good resistance to overcharge and operate over a wide range of temperatures from 150 to 400 C with less corrosion problems.

Correlations in the three-dimensional Lyman-alpha forest contaminated by high column density absorbers

NASA Astrophysics Data System (ADS)

Rogers, Keir K.; Bird, Simeon; Peiris, Hiranya V.; Pontzen, Andrew; Font-Ribera, Andreu; Leistedt, Boris

2018-05-01

Correlations measured in three dimensions in the Lyman-alpha forest are contaminated by the presence of the damping wings of high column density (HCD) absorbing systems of neutral hydrogen (H I; having column densities N(H I) > 1.6 × 10^{17} atoms cm^{-2}), which extend significantly beyond the redshift-space location of the absorber. We measure this effect as a function of the column density of the HCD absorbers and redshift by measuring three-dimensional (3D) flux power spectra in cosmological hydrodynamical simulations from the Illustris project. Survey pipelines exclude regions containing the largest damping wings. We find that, even after this procedure, there is a scale-dependent correction to the 3D Lyman-alpha forest flux power spectrum from residual contamination. We model this residual using a simple physical model of the HCD absorbers as linearly biased tracers of the matter density distribution, convolved with their Voigt profiles and integrated over the column density distribution function. We recommend the use of this model over existing models used in data analysis, which approximate the damping wings as top-hats and so miss shape information in the extended wings. The simple `linear Voigt model' is statistically consistent with our simulation results for a mock residual contamination up to small scales (|k| < 1 h Mpc^{-1}). It does not account for the effect of the highest column density absorbers on the smallest scales (e.g. |k| > 0.4 h Mpc^{-1} for small damped Lyman-alpha absorbers; HCD absorbers with N(H I) ˜ 10^{21} atoms cm^{-2}). However, these systems are in any case preferentially removed from survey data. Our model is appropriate for an accurate analysis of the baryon acoustic oscillations feature. It is additionally essential for reconstructing the full shape of the 3D flux power spectrum.

The Design, Synthesis and Screening of Potential Pyridinium Oxime Prodrugs

DTIC Science & Technology

1985-09-30

210 ml stainless steel bombs were each filled with 100 ml of 28% aqueous NH4OH, 2.8 g (11 imol) of copper sulfate pentahydrate , and 15 g (87 mol) of...ethyl acetate. The organic extracts were washed twice with brine, dried over sodium sulfate , filtered and flashed to a black oil. A vacuum distillation...extracts were washed with brine, dried with sodium sulfate , filtered and flashed. The residue was then purified by column chromatography (silica gel

A Quasi-Solid-State Sodium-Ion Capacitor with High Energy Density.

PubMed

Wang, Faxing; Wang, Xiaowei; Chang, Zheng; Wu, Xiongwei; Liu, Xiang; Fu, Lijun; Zhu, Yusong; Wu, Yuping; Huang, Wei

2015-11-18

A quasi-solid-state sodium-ion capacitor is demonstrated with nanoporous disordered carbon and macroporous graphene as the negative and positive electrodes, respectively, using a sodium-ion-conducting gel polymer electrolyte. It can operate at a cell voltage as high as 4.2 V with an energy density of record high 168 W h kg(-1). © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Cloudy Skies over AGN: Observations with Simbol-X

NASA Astrophysics Data System (ADS)

Salvati, M.; Risaliti, G.

2009-05-01

Recent time-resolved spectroscopic X-ray studies of bright obscured AGN show that column density variability on time scales of hours/days may be common, at least for sources with NH>1023 cm-2. This opens new oppurtunities in the analysis of the structure of the circumnuclear medium and of the X-ray source: resolving the variations due to single clouds covering/uncovering the X-ray source provides tight constraints on the source size, the clouds' size and distance, and their average number, density and column density. We show how Simbol-X will provide a breakthrough in this field, thanks to its broad band coverage, allowing (a) to precisely disentangle the continuum and NH variations, and (2) to extend the NH variability analysis to column densities >1023 cm-2.

Preparation of 3D Architecture Graphdiyne Nanosheets for High-Performance Sodium-Ion Batteries and Capacitors.

PubMed

Wang, Kun; Wang, Ning; He, Jianjiang; Yang, Ze; Shen, Xiangyan; Huang, Changshui

2017-11-22

Here, we apply three-dimensional (3D) architecture graphdiyne nanosheet (GDY-NS) as anode materials for sodium-ion storage devices achieving high energy and power performance along with excellent cyclic ability. The contribution of 3D architecture nanostructure and intramolecular pores of the GDY-NS can substantially optimize the sodium storage behavior through the accommodated intramolecular pore, 3D interconnective porous structure, and increased activity sites to facilitate a fast sodium-ion-diffusion channel. The contribution of butadiyne linkages and the formation of a stable solid electrolyte interface layer are directly confirmed through the in situ Raman measurement. The GDY-NS-based sodium-ion batteries exhibit a stable reversible capacity of approximately 812 mAh g -1 at a current density of 0.05 A g -1 ; they maintain more than 405 mAh g -1 over 1000 cycles at a current density of 1 A g -1 . Furthermore, the sodium-ion capacitors could deliver a capacitance more than 200 F g -1 over 3000 cycles at 1 A g -1 and display an initial specific energy as high as 182.3 Wh kg -1 at a power density of 300 W kg -1 and maintain specific energy of 166 Wh kg -1 even at a power density of 15 000 W kg -1 . The high energy and power density along with excellent cyclic performance based on the GDY-NS anode offers a great potential toward application on next-generation energy storage devices.

Sodium modified molybdenum sulfide via molten salt electrolysis as an anode material for high performance sodium-ion batteries.

PubMed

Wang, Shuai; Tu, Jiguo; Yuan, Yan; Ma, Rui; Jiao, Shuqiang

2016-01-28

The paper reports a facile and cost effective method for fabricating sodium molybdenum sulfide nanoparticles through using MoS2 sheets as the precursor by sodium-modification. The electrochemical performances of sodium molybdenum sulfide nanoparticles are studied as anode materials for sodium-ion batteries. The galvanostatic charge-discharge measurements have been performed in a voltage range of 0.01-2.6 V vs. Na(+)/Na under different current densities, using the as-prepared sodium molybdenum sulfide nanoparticles as a working electrode. Typically, the initial discharge and charge capacities of sodium molybdenum sulfide nanoparticles are 475 and 380 mA h g(-1), respectively, at a current density of 20 mA g(-1). The sodium molybdenum sulfide nanoparticles exhibit high capacity with a reversible discharge capacity of about 190 mA h g(-1) after 100 cycles. It should be emphasized that the discharge reaction consists of two steps which correspond to voltage plateaus of 0.93 V and 0.85 V vs. Na(+)/Na in the first discharge curve of the Na/MoS2 battery, respectively. But there is only one apparent voltage plateau in the Na/Na-Mo-S battery, and it reduces to below 0.5 V vs. Na(+)/Na, which can enhance the power density. All of the findings demonstrate that sodium molybdenum sulfide nanoparticles have steady cycling performance and environmental and cost friendliness as next generation secondary batteries.

Discovery of sodium and potassium vapor in the atmosphere of the moon

NASA Technical Reports Server (NTRS)

Potter, A. E.; Morgan, T. H.

1988-01-01

A ground-based telescopic study of the lunar surface with high resolution spectroscopy has led to the discovery of sodium and potassium vapor 'atmospheres'. The scale height for the sodium atmosphere is 120 + or - 42 km, and for potassium 90 + or - 20 km; these values imply that the effective temperature of the two elements closely approximates that of the lunar surface. The sodium density at the south polar region is similar to that at the subsolar point, indicating widespread distribution of the vapor. The ratio of sodium to potassium densities, at 6 (+ or - 3):1, is close to the lunar surface ratio and suggests that the atmosphere originated in the vaporization of surface minerals.

Experimental investigation on temperature distribution of foamed concrete filled steel tube column under standard fire

NASA Astrophysics Data System (ADS)

Kado, B.; Mohammad, S.; Lee, Y. H.; Shek, P. N.; Kadir, M. A. A.

2018-04-01

Standard fire test was carried out on 3 hollow steel tube and 6 foamed concrete filled steel tube columns. Temperature distribution on the columns was investigated. 1500 kg/m3 and 1800 kg/m3 foamed concrete density at 15%, 20% and 25% load level are the parameters considered. The columns investigated were 2400 mm long, 139.7 mm outer diameter and 6 mm steel tube thickness. The result shows that foamed concrete filled steel tube columns has the highest fire resistance of 43 minutes at 15% load level and low critical temperature of 671 ºC at 25% load level using 1500 kg/m3 foamed concrete density. Fire resistance of foamed concrete filled column increases with lower foamed concrete strength. Foamed concrete can be used to provide more fire resistance to hollow steel column or to replace normal weight concrete in concrete filled columns. Since filling hollow steel with foamed concrete produce column with high fire resistance than unfilled hollow steel column. Therefore normal weight concrete can be substituted with foamed concrete in concrete filled column, it will reduces the self-weight of the structure because of its light weight at the same time providing the desired fire resistance.

Natriuretic factor, a lasting enigma.

PubMed

Licht, A; Fine, L G; Bourgoignie, J J

1978-01-01

A gel filtration fraction of urine from patients with chronic uremia (natriuretic factor) decreases potential difference, net sodium flux and lumen to peritubular flux of sodium across the isolated rabbit cortical collecting tubule. These effects are consistent with the possibility that natriuretic factor represents a modulator of sodium excretion in the mammalian nephron. Natriuretic factor induces a dose-dependent inhibition of short-circuit current in the isolated toad bladder. By comparing the effects of natriuretic factor to those of a standard unit of reference, it may be possible to develop a quantitative assay for natriuretic factor. The acidic nature of natriuretic factor was confirmed by cation exchange column in a high pressure liquid chromatography system.

Sodium titanate nanotubes as negative electrode materials for sodium-ion capacitors.

PubMed

Yin, Jiao; Qi, Li; Wang, Hongyu

2012-05-01

The lithium-based energy storage technology is currently being considered for electric automotive industry and even electric grid storage. However, the hungry demand for vast energy sources in the modern society will conflict with the shortage of lithium resources on the earth. The first alternative choice may be sodium-related materials. Herein, we propose an electric energy storage system (sodium-ion capacitor) based on porous carbon and sodium titanate nanotubes (Na-TNT, Na(+)-insertion compounds) as positive and negative electrode materials, respectively, in conjunction with Na(+)-containing non-aqueous electrolytes. As a low-voltage (0.1-2 V) sodium insertion nanomaterial, Na-TNT was synthesized via a simple hydrothermal reaction. Compared with bulk sodium titanate, the predominance of Na-TNT is the excellent rate performance, which exactly caters to the need for electrochemical capacitors. The sodium-ion capacitors exhibited desirable energy density and power density (34 Wh kg(-1), 889 W kg(-1)). Furthermore, the sodium-ion capacitors had long cycling life (1000 cycles) and high coulombic efficiency (≈ 98 % after the second cycle). More importantly, the conception of sodium-ion capacitor has been put forward.

Constraining the H2 column density distribution at z ˜ 3 from composite DLA spectra

NASA Astrophysics Data System (ADS)

Balashev, S. A.; Noterdaeme, P.

2018-07-01

We present the detection of the average H2 absorption signal in the overall population of neutral gas absorption systems at z˜ 3 using composite absorption spectra built from the Sloan Digital Sky Survey-III damped Lyman α catalogue. We present a new technique to directly measure the H2 column density distribution function f_H_2(N) from the average H2 absorption signal. Assuming a power-law column density distribution, we obtain a slope β = -1.29 ± 0.06(stat) ± 0.10 (sys) and an incidence rate of strong H2 absorptions [with N(H2) ≳ 1018 cm-2] to be 4.0 ± 0.5(stat) ± 1.0 (sys) per cent in H I absorption systems with N(H I) ≥1020 cm-2. Assuming the same inflexion point where f_H_2(N) steepens as at z = 0, we estimate that the cosmological density of H2 in the column density range log N(H_2) (cm^{-2})= 18{-}22 is {˜ } 15 per cent of the total. We find one order of magnitude higher H2 incident rate in a sub-sample of extremely strong damped Lyman α absorption systems (DLAs) [log N(H I) (cm^{-2}) ≥ 21.7], which, together with the derived shape of f_H_2(N), suggests that the typical H I-H2 transition column density in DLAs is log N(H)(cm-2) ≳ 22.3 in agreement with theoretical expectations for the average (low) metallicity of DLAs at high-z.

Constraining the H2 column density distribution at z˜3 from composite DLA spectra

NASA Astrophysics Data System (ADS)

Balashev, S. A.; Noterdaeme, P.

2018-04-01

We present the detection of the average H2 absorption signal in the overall population of neutral gas absorption systems at z ˜ 3 using composite absorption spectra built from the Sloan Digital Sky Survey-III damped Lyman-α catalogue. We present a new technique to directly measure the H2 column density distribution function f_H_2(N) from the average H2 absorption signal. Assuming a power-law column density distribution, we obtain a slope β = -1.29 ± 0.06(stat) ± 0.10 (sys) and an incidence rate of strong H2 absorptions (with N(H2) ≳ 1018 cm-2) to be 4.0 ± 0.5(stat) ± 1.0 (sys) % in H I absorption systems with N(H I)≥1020 cm-2. Assuming the same inflexion point where f_H_2(N) steepens as at z = 0, we estimate that the cosmological density of H2 in the column density range log N(H_2) (cm^{-2})= 18-22 is ˜15% of the total. We find one order of magnitude higher H2 incident rate in a sub-sample of extremely strong DLAs (log N(H I) (cm^{-2}) ≥ 21.7), which, together with the the derived shape of f_H_2(N), suggests that the typical H I-H2 transition column density in DLAs is log N(H)(cm-2) ≳ 22.3 in agreement with theoretical expectations for the average (low) metallicity of DLAs at high-z.

Investigation of crystallization kinetics of sodium bicarbonate in a continuous stirred tank crystallizer

NASA Astrophysics Data System (ADS)

Zhu, Yi; Haut, Benoît; Halloin, Veronique; Delplancke-Ogletree, Marie-Paule

2005-08-01

In our previous work [J. Crystal Growth 263 (2004) 459], a supersaturation determination method using a high-precision densimeter was designed and developed for monitoring sodium bicarbonate supersaturation in the sodium carbonate-bicarbonate system, a two-component solution in equilibrium. In the present paper, we apply this method to the study of sodium bicarbonate continuous crystallization. It gives us access to the sodium bicarbonate supersaturation evolution. The sodium bicarbonate supersaturation evolution and their crystallization kinetics obtained in a continuous stirred tank crystallizer are investigated under different operational conditions, such as residence time, initial supersaturation and seeding. The induction time determined by density measurements is discussed. Mathematical modeling is used to interpret the supersaturation evolution. It is shown that measuring the density gives satisfying performances for studying the crystallization of a two-component solution in equilibrium, such as the sodium carbonate-bicarbonate system.

In vivo NMR imaging of sodium-23 in the human head.

PubMed

Hilal, S K; Maudsley, A A; Ra, J B; Simon, H E; Roschmann, P; Wittekoek, S; Cho, Z H; Mun, S K

1985-01-01

We report the first clinical nuclear magnetic resonance (NMR) images of cerebral sodium distribution in normal volunteers and in patients with a variety of pathological lesions. We have used a 1.5 T NMR magnet system. When compared with proton distribution, sodium shows a greater variation in its concentration from tissue to tissue and from normal to pathological conditions. Image contrast calculated on the basis of sodium concentration is 7 to 18 times greater than that of proton spin density. Normal images emphasize the extracellular compartments. In the clinical studies, areas of recent or old cerebral infarction and tumors show a pronounced increase of sodium content (300-400%). Actual measurements of image density values indicate that there is probably a further accentuation of the contrast by the increased "NMR visibility" of sodium in infarcted tissue. Sodium imaging may prove to be a more sensitive means for early detection of some brain disorders than other imaging methods.

Efficiency gain limits of the parallel segmented inlet and outlet flow concept in analytical liquid chromatography columns suffering from radial transcolumn packing density gradients.

PubMed

Broeckhoven, Ken; Desmet, Gert

2012-10-05

The maximal gain in efficiency that can be expected from the use of the segmented column end fittings that were recently introduced to alleviate the effect of transcolumn packing density gradients has been quantified and generalized using numerical computations of the band broadening process. It was found that, for an unretained compound in a column with a parabolic packing density gradient, the use of a segmented inlet or a segmented outlet allows to eliminate about 60-100% of the plate height contribution (H(tc)) originating from a parabolic transcolumn velocity gradient in a d(c)=4.6 mm column. In a d(c)=2.1 mm column, these percentages change from 10 to 100%. Using a combined segmented in- and outlet, H(tc) can be reduced by about 90-100% (d(c)=4.6 mm column) or 20-100% (d(c)=2.1 mm column). The strong variation of these gain percentages is due to fact that they depend very strongly on the column length and the flow rate. Dimensionless graphs have been established that allow to directly quantify the effect for each specific case. It was also found that, in agreement with one's physical intuition, trans-column velocity profiles that are more flat in the central region benefit more from the concept than sharp, parabolic-like profiles. The gain margins furthermore tend to become smaller with increasing retention and increasing diffusion coefficient. Copyright © 2012 Elsevier B.V. All rights reserved.

A magnesium–sodium hybrid battery with high operating voltage

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dong, Hui; Li, Yifei; Liang, Yanliang

2016-06-10

We report a high performance magnesium-sodium hybrid battery utilizing a magnesium-sodium dual-salt electrolyte, a magnesium anode, and a Berlin green cathode. The cell delivers an average discharge voltage of 2.2 V and a reversible capacity of 143 mAh g -1. We also demonstrate the cell with an energy density of 135 Wh kg -1 and a high power density of up to 1.67 kW kg -1.

Pressure, temperature and density drops along supercritical fluid chromatography columns in different thermal environments. III. Mixtures of carbon dioxide and methanol as the mobile phase.

PubMed

Poe, Donald P; Veit, Devon; Ranger, Megan; Kaczmarski, Krzysztof; Tarafder, Abhijit; Guiochon, Georges

2014-01-03

The pressure, temperature and density drops along SFC columns eluted with a CO2/methanol mobile phase were measured and compared with theoretical values. For columns packed with 3- and 5-μm particles the pressure and temperature drops were measured using a mobile phase of 95% CO2 and 5% methanol at a flow rate of 5mL/min, at temperatures from 20 to 100°C, and outlet pressures from 80 to 300bar. The density drop was calculated based on the temperature and pressure at the column inlet and outlet. The columns were suspended in a circulating air bath, either bare or covered with foam insulation. The experimental measurements were compared to theoretical results obtained by numerical simulation. For the convective air condition at outlet pressures above 100bar the average difference between the experimental and calculated temperature drops and pressure drops were 0.1°C and 0.7% for the bare 3-μm column, respectively, and were 0.6°C and 4.1% for the insulated column. The observed temperature drops for the insulated columns are consistent with those predicted by the Joule-Thomson coefficients for isenthalpic expansion. The dependence of the temperature and the pressure drops on the Joule-Thomson coefficient and kinematic viscosity are described for carbon dioxide mobile phases containing up to 20% methanol. Copyright © 2013 Elsevier B.V. All rights reserved.

Galactic cold cores. IX. Column density structures and radiative-transfer modelling

NASA Astrophysics Data System (ADS)

Juvela, M.; Malinen, J.; Montillaud, J.; Pelkonen, V.-M.; Ristorcelli, I.; Tóth, L. V.

2018-06-01

Context. The Galactic Cold Cores (GCC) project has made Herschel photometric observations of interstellar clouds where Planck detected compact sources of cold dust emission. The fields are in different environments and stages of star formation. Aims: Our aim is to characterise the structure of the clumps and their parent clouds, and to study the connections between the environment and the formation of gravitationally bound objects. We also examine the accuracy to which the structure of dense clumps can be determined from sub-millimetre data. Methods: We use standard statistical methods to characterise the GCC fields. Individual clumps are extracted using column density thresholding. Based on sub-millimetre measurements, we construct a three-dimensional radiative transfer (RT) model for each field. These are used to estimate the relative radiation field intensities, to probe the clump stability, and to examine the uncertainty of column density estimates. We examine the structural parameters of the clumps, including their radial column density profiles. Results: In the GCC fields, the structure noise follows the relations previously established at larger scales and in lower-density clouds. The fractal dimension has no significant dependence on column density and the values DP = 1.25 ± 0.07 are only slightly lower than in typical molecular clouds. The column density probability density functions (PDFs) exhibit large variations, for example, in the case of externally compressed clouds. At scales r > 0.1 pc, the radial column density distributions of the clouds follow an average relation of N r-1. In spite of a great variety of clump morphologies (and a typical aspect ratio of 1.5), clumps tend to follow a similar N r-1 relation below r 0.1 pc. RT calculations indicate only factor 2.5 variation in the local radiation field intensity. The fraction of gravitationally bound clumps increases significantly in regions with AV > 5 mag but most bound objects appear to be pressure-confined. Conclusions: The host clouds of the cold clumps in the GCC sample have statistical properties similar to general molecular clouds. The gravitational stability, peak column density, and clump orientation are connected to the cloud background while most other statistical clump properties (e.g. DP and radial profiles) are insensitive to the environment. The study of clump morphology should be continued with a comparison with numerical simulations. Planck (http://www.esa.int/Planck) is a project of the European Space Agency (ESA) with instruments provided by two scientific consortia funded by ESA member states (in particular the lead countries: France and Italy) with contributions from NASA (USA), and telescope reflectors provided in a collaboration between ESA and a scientific consortium led and funded by Denmark.Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.

[Adaptation of the (18)FDG module for the preparation of a sodium fluoride [(18)F] injection solution in agreement with the United States (USP 32) and European Pharmacopeia (PhEur 6)].

PubMed

Martínez, T; Cordero, B; Medín, S; Sánchez Salmón, A

2011-01-01

To establish an automated procedure for the preparation of sodium fluoride (18)F injection using the resources available in our laboratory for the preparation of (18)FDG and to analyze the repercussion of the conditioning column of the fluoride ion entrapment on the characteristics of the final product. The sequence of an (18)FDG synthesis module prepared so that it traps the fluoride ion from the cyclotron in ion-exchange resin diluted with 0.9% sodium chloride. The final solution was dosified and sterilized in a final vial in an automatized dispensing module. Three different column conditioning protocols within the process were tested. Quality controls were run according to USP 32 and EurPh 6, adding control of ethanol levels of residual solvent and quality controls of the solution at 8 h post-preparation. Activation of the resin cartridges with ethanol and water was the chosen procedure, with fluoride ion trapping > 95% and pH around 7. Ethanol levels were < 5.000 ppm. Quality controls at 8 h indicated that the solution was in compliance with the USP 32 and EurPh 6 specifications. This is an easy, low-cost, reliable automated method for sodium fluoride preparation in PET facilities with existing equipment for (18)FDG synthesis and quality control. Copyright © 2010 Elsevier España, S.L. y SEMNIM. All rights reserved.

Regional analysis of the effect of paved roads on sodium and chloride in lakes.

PubMed

Kelting, Daniel L; Laxson, Corey L; Yerger, Elizabeth C

2012-05-15

Salinization of surface water from sodium chloride (road salt) applied to paved roads is a widely recognized environmental concern in the northern hemisphere, yet practical information to improve winter road management to reduce the environmental impacts of this deicer is lacking. The purpose of our study was to provide such information by developing baseline concentrations for sodium and chloride for lakes in watersheds without paved roads, and then determining the relationship between these ions and density, type, and proximity of paved roads to shoreline. We used average summer (June-September) sodium and chloride data for 138 lakes combined in a watershed based analysis of paved road networks in the Adirondack Park of New York, U.S.A. The watersheds used in our study represented a broad range in paved road density and type, 56 of which had no paved roads. Median lake sodium and chloride concentrations in these 56 watersheds averaged 0.55 and 0.24 mg/L, respectively. In contrast, the median sodium and chloride concentrations for the 82 lakes in watersheds with paved roads were 3.60 and 7.22 mg/L, respectively. Paved road density (lane-km/km(2)) was positively correlated with sodium and chloride concentrations, but only state roads were significantly correlated with sodium and chloride while local roads were not. State road density alone explained 84 percent of the variation in both ions. We also successfully modeled the relationship between road proximity to shoreline and sodium and chloride concentrations in lakes, which allowed us to identify sections of road that contributed more to explaining the variation in sodium and chloride in lakes. This model and our approach could be used as part of larger efforts to identify environmentally sensitive areas where alternative winter road management treatments should be applied. Copyright © 2012 Elsevier Ltd. All rights reserved.

Sodium and potassium excretion are related to bone mineral density in women with coeliac disease.

PubMed

Turner, Kirsty M; Clifton, Peter M; Keogh, Jennifer B

2015-04-01

Women with coeliac disease may have a lower bone mineral density due to the malabsorption of calcium before diagnosis. A high sodium excretion is associated with increased calcium and bone loss. Our aim was to describe the bone mineral density (BMD) and sodium excretion in women with coeliac disease. In a cross-sectional study BMD of the lumbar spine and hip was assessed by dual energy X-ray absorptiometry. Sodium, potassium and calcium excretion were measured from a 24 h urine collection. In 33 women (51 ± 16 yr) BMD was 1.14 ± 0.19 g/cm(2) and 0.94 ± 0.14 g/cm(2) at the lumbar spine and hip respectively. Age matched Z-scores were -0.1 ± 1.2 and -0.3 ± 1.1 at lumbar spine and hip respectively. Sodium excretion was 107 ± 51 mmol/d; 14 (42%) had a sodium excretion >100 mmol Na/d (145 ± 45 mmol/d). Potassium and calcium excretion were 87 ± 25 mmol/d and 4.1 ± 2.0 mmol/d respectively. In women with Na excretion >100 mmol Na/d, Ca excretion was significantly greater than those with <100 mmol/d (4.9 ± 2.0 vs 3.4 ± 1.8, p < 0.05). Sodium excretion and BMI were positively correlated (r = 0.61, p < 0.001) as were sodium and calcium excretion (r = 0.43, p < 0.05). Sodium excretion was inversely related to femoral neck BMD (t = -2.4 p = 0.023) after adjustment for weight, age, years since diagnosis and potassium excretion. Weight, but no other variable, was a predictor of BMD at the lumbar spine (t = 2.58 p = 0.018). Sodium excretion was inversely related and potassium excretion positively related to femoral neck density which was similar to age matched women without coeliac disease. Copyright © 2014 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism. All rights reserved.

Maximizing performance in supercritical fluid chromatography using low-density mobile phases.

PubMed

Gritti, Fabrice; Fogwill, Michael; Gilar, Martin; Jarrell, Joseph A

2016-10-14

The performance of a 3.0mm×150mm column packed with 1.8μm fully porous HSS-SB-C 18 particles was investigated in supercritical fluid chromatography (SFC) with low-density, highly expansible carbon dioxide. These conditions are selected for the analysis of semi-volatile compounds. Elevated temperatures (>100°C) were then combined with low column back pressures (<100bar). In this work, the inlet temperature of pure carbon dioxide was set at 107°C, the active back pressure regulator (ABPR) pressure was fixed at 100bar, and the flow rate was set at 2.1mL/min at 12°C (liquefied carbon dioxide) and at an inlet column pressure close to 300bar. Nine n-alkylbenzenes (from benzene to octadecylbenzene) were injected under linear (no sample overload) conditions. The severe steepness of the temperature gradients across the column diameter were predicted from a simplified heat transfer model. Such conditions dramatically lower the column performance by affecting the symmetry of the peak shape. In order to cope with this problem, three different approaches were experimentally tested. They include (1) the decoupling and the proper selection of the inlet eluent temperature with respect to the oven temperature, (2) the partial thermal insulation of the column using polyethylene aerogel, and (3) the application of a high vacuum (10 -5 Torr provided by a turbo-molecular pump) in a housing chamber surrounding the whole column body. The results reveal that (1) the column efficiency can be maximized by properly selecting the difference between the eluent and the oven temperatures, (2) the mere wrapping of the column with an excellent insulating material is insufficient to fully eliminate heat exchanges by conduction and the undesirable radial density gradients across the column i.d., and (3) the complete thermal insulation of the SFC column under high vacuum allows to maximize the column efficiency by maintaining the integrity of the peak shape. Copyright © 2016 Elsevier B.V. All rights reserved.

A Novel High Performance Liquid Chromatographic Method for Simultaneous Determination of Ceftriaxone and Sulbactam in Sulbactomax

PubMed Central

Shrivastava, Sanjay Mohan; Singh, Rajkumar; Tariq, Abu; Siddiqui, Masoom Raza; Yadav, Jitendar; Negi, P. S.; Chaudhary, Manu

2009-01-01

An isocratic liquid chromatographic method with UV detection at 220 nm is described for simultaneous determination of ceftriaxone sodium and sulbactam sodium in Sulbactomax. Chromatographic separation of two drugs was achieved on a Hypersil ODS C-18 column using a mobile phase consisting of a binary mixture of acetonitrile and tetrabutyl ammonium hydroxide adjusted to pH7.0 with orthophosphoric acid in ratio 70:30. The developed Liquid Chromatographic method offers symmetric peak shape, good resolution and reasonable retention time for both drugs. Linearity, accuracy and precision were found to be acceptable over the concentration range of 125-750 ppm for ceftriaxone sodium and 62.5-375 ppm for sulbactam sodium. The LC method can be used for the quality control of formulated products containing ceftriaxone and sulbactam. PMID:23675112

Molecular column densities in selected model atmospheres. [chemical analysis of carbon stars

NASA Technical Reports Server (NTRS)

Johnson, H. R.; Beebe, R. F.; Sneden, C.

1974-01-01

From an examination of predicted column densities, the following conclusions were drawn: (1) The SiO ought to be visible in carbon stars which were generated from triple alpha burning, but absent from carbon stars generated from the CNO bi-cycle. (2) Variation in the observed relative strengths of TiO and ZrO is indicative of real differences in the ratio Ti/Zr. (3) The TiO/ZrO ratio shows a small variation as C/O and effective temperature is changed. (4) Column density of silicon dicarbide (SiC2) is sensitive to abundance, temperature, and gravity; hence all relationships between the strength of SiC2 and other stellar parameters will show appreciable scatter. There is however, a substantial luminosity effect present in the SiC2 column densities. (5) Unexpectedly, SiC2 is anti-correlated with C2. (6) The presence of SiC2 in a carbon star eliminates the possibility of these stars having temperatures greater than or equal to 3000 K, or being produced through the CNO bi-cycle.

A Novel High Energy Density Rechargeable Hybrid Sodium-Air Cell with Acidic Electrolyte.

PubMed

Kang, Yao; Su, Fengmei; Zhang, Qingkai; Liang, Feng; Adair, Keegan R; Chen, Kunfeng; Xue, Dongfeng; Hayashi, Katsuro; Cao, Shan Cecilia; Yadegari, Hossein; Sun, Xueliang

2018-06-22

Low cost, high energy density and highly efficient devices for energy storage have long been desired in our society. Herein, a novel high energy density hybrid sodium-air cell was fabricated successfully based on acidic catholytes. Such a hybrid sodium-air cell possess a high theoretical voltage of 3.94 V, capacity of 1121 mAh g-1, and energy density of 4418 Wh kg-1. Firstly, the buffering effect of an acidic solution was demonstrated, which provides relatively long and stable cell discharge behaviours. Secondly, the catholyte of hybrid sodium-air cells were optimized systematically from the solutions of 0.1 M H3PO4 + 0.1 M Na2SO4 to 0.1 M HAc + 0.1 M NaAc, and it was found that the cells with 0.1 M H3PO4 + 0.1 M Na2SO4 displayed maximum power density of 34.9 mW cm-2. The cell with 0.1 M H3PO4 + 0.1 M Na2SO4 displayed higher discharge capacity of 896 mAh g-1. Moreover, the fabricated acidic hybrid sodium-air cells exhibited stable cycling performance in ambient air, and they delivered a low voltage gap around 0.3 V when the current density is 0.13 mA cm-2, leading to a high energy efficiency up to 90%. Therefore, the present study provides new opportunities to develop highly cost-effective energy storage technologies.

Copper chloride cathode for a secondary battery

NASA Technical Reports Server (NTRS)

Bugga, Ratnakumar V. (Inventor); Distefano, Salvador (Inventor); Nagasubramanian, Ganesan (Inventor); Bankston, Clyde P. (Inventor)

1990-01-01

Higher energy and power densities are achieved in a secondary battery based on molten sodium and a solid, ceramic separator such as a beta alumina and a molten catholyte such as sodium tetrachloroaluminate and a copper chloride cathode. The higher cell voltage of copper chloride provides higher energy densities and the higher power density results from increased conductivity resulting from formation of copper as discharge proceeds.

Multi-wavelength campaign on NGC 7469. II. Column densities and variability in the X-ray spectrum

NASA Astrophysics Data System (ADS)

Peretz, U.; Behar, E.; Kriss, G. A.; Kaastra, J.; Arav, N.; Bianchi, S.; Branduardi-Raymont, G.; Cappi, M.; Costantini, E.; De Marco, B.; Di Gesu, L.; Ebrero, J.; Kaspi, S.; Mehdipour, M.; Middei, R.; Paltani, S.; Petrucci, P. O.; Ponti, G.; Ursini, F.

2018-01-01

We have investigated the ionic column density variability of the ionized outflows associated with NGC 7469, to estimate their location and power. This could allow a better understanding of galactic feedback of AGNs to their host galaxies. Analysis of seven XMM-Newton grating observations from 2015 is reported. We used an individual-ion spectral fitting approach, and compared different epochs to accurately determine variability on timescales of years, months, and days. We find no significant column density variability in a ten-year period implying that the outflow is far from the ionizing source. The implied lower bound on the ionization equilibrium time, ten years, constrains the lower limit on the distance to be at least 12 pc, and up to 31 pc, much less but consistent with the 1 kpc wide starburst ring. The ionization distribution of column density is reconstructed from measured column densities, nicely matching results of two 2004 observations, with one large high ionization parameter (ξ) component at 2 < log ξ< 3.5, and one at 0.5 < log ξ< 1 in cgs units. The strong dependence of the expression for kinetic power, ∝ 1 /ξ, hampers tight constraints on the feedback mechanism of outflows with a large range in ionization parameter, which is often observed and indicates a non-conical outflow. The kinetic power of the outflow is estimated here to be within 0.4 and 60% of the Eddington luminosity, depending on the ion used to estimate ξ.

Comparison of the excretion of sodium and meglumine diatrizoate at urography with simulated compression: an experimental study in the rat.

PubMed

Owman, T

1981-07-01

In the experimental model in the rabbit the excretion of sodium and meglumine diatrizoate, respectively, have been compared. Urographic density which was estimated through renal pelvic volume as calculated according to previous experiments (Owman 1978; Owman & Olin 1980) and urinary iodine concentration, is suggested to be more accurate than mere determination of urine iodine concentration and diuresis when evaluating and comparing urographic contrast media experimentally. More reliable dose optima are probably found when calculating density rather than determining urine concentrations. Of the examined media in this investigation, the sodium salt of diatrizoate was not superior to the meglumine salt in dose ranges up to 320 mg I/kg body weight, while at higher doses sodium diatrizoate gave higher urinary iodine concentrations and higher estimated density.

Observations of peculiar sporadic sodium structures and their relation with wind variations

NASA Astrophysics Data System (ADS)

Sridharan, S.; Prasanth, P. Vishnu; Kumar, Y. Bhavani; Ramkumar, Geetha; Sathishkumar, S.; Raghunath, K.

2009-04-01

Resonance lidar observations of sodium density in the upper mesosphere region over Gadanki (13.5°N, 79.2°E) rarely show complex structures with rapid enhancements of sodium density, completely different from normal sporadic sodium structures. The hourly averaged meteor radar zonal winds over Trivandrum (8.5°N, 76.5°E) show an eastward shear with altitude during the nights, when these events are formed. As suggested by Kane et al. [2001. Joint observations of sodium enhancements and field-aligned ionospheric irregularities. Geophysical Research Letters 28, 1375-1378], our observations show that the complex structures may be formed due to Kelvin-Helmholtz instability, which can occur in the region of strong wind shear.

Physical properties of Southern infrared dark clouds

NASA Astrophysics Data System (ADS)

Vasyunina, T.; Linz, H.; Henning, Th.; Stecklum, B.; Klose, S.; Nyman, L.-Å.

2009-05-01

Context: What are the mechanisms by which massive stars form? What are the initial conditions for these processes? It is commonly assumed that cold and dense Infrared Dark Clouds (IRDCs) represent the birth-sites of massive stars. Therefore, these clouds have been receiving an increasing amount of attention, and their analysis offers the opportunity to tackle the afore mentioned questions. Aims: To enlarge the sample of well-characterised IRDCs in the southern hemisphere, where ALMA will play a major role in the near future, we have developed a program to study the gas and dust of southern infrared dark clouds. The present paper attempts to characterize the continuum properties of this sample of IRDCs. Methods: We cross-correlated 1.2 mm continuum data from SIMBA bolometer array mounted on SEST telescope with Spitzer/GLIMPSE images to establish the connection between emission sources at millimeter wavelengths and the IRDCs that we observe at 8 μm in absorption against the bright PAH background. Analysing the dust emission and extinction enables us to determine the masses and column densities, which are important quantities in characterizing the initial conditions of massive star formation. We also evaluated the limitations of the emission and extinction methods. Results: The morphology of the 1.2 mm continuum emission is in all cases in close agreement with the mid-infrared extinction. The total masses of the IRDCs were found to range from 150 to 1150 M_⊙ (emission data) and from 300 to 1750 M_⊙ (extinction data). We derived peak column densities of between 0.9 and 4.6 × 1022 cm-2 (emission data) and 2.1 and 5.4 × 1022 cm-2 (extinction data). We demonstrate that the extinction method is unreliable at very high extinction values (and column densities) beyond AV values of roughly 75 mag according to the Weingartner & Draine (2001) extinction relation RV = 5.5 model B (around 200 mag when following the common Mathis (1990, ApJ, 548, 296) extinction calibration). By taking the spatial resolution effects into account and restoring the column densities derived from the dust emission to a linear resolution of 0.01 pc, peak column densities of 3-19 × 1023 cm-2 are obtained, which are much higher than typical values for low-mass cores. Conclusions: Taking into account the spatial resolution effects, the derived column densities are beyond the column density threshold of 3.0 × 1023 cm-2 required by theoretical considerations for massive star formation. We conclude that the values of column densities derived for the selected IRDC sample imply that these objects are excellent candidates for objects in the earliest stages of massive star formation.

High-Energy-Density Metal-Oxygen Batteries: Lithium-Oxygen Batteries vs Sodium-Oxygen Batteries.

PubMed

Song, Kyeongse; Agyeman, Daniel Adjei; Park, Mihui; Yang, Junghoon; Kang, Yong-Mook

2017-12-01

The development of next-generation energy-storage devices with high power, high energy density, and safety is critical for the success of large-scale energy-storage systems (ESSs), such as electric vehicles. Rechargeable sodium-oxygen (Na-O 2 ) batteries offer a new and promising opportunity for low-cost, high-energy-density, and relatively efficient electrochemical systems. Although the specific energy density of the Na-O 2 battery is lower than that of the lithium-oxygen (Li-O 2 ) battery, the abundance and low cost of sodium resources offer major advantages for its practical application in the near future. However, little has so far been reported regarding the cell chemistry, to explain the rate-limiting parameters and the corresponding low round-trip efficiency and cycle degradation. Consequently, an elucidation of the reaction mechanism is needed for both lithium-oxygen and sodium-oxygen cells. An in-depth understanding of the differences and similarities between Li-O 2 and Na-O 2 battery systems, in terms of thermodynamics and a structural viewpoint, will be meaningful to promote the development of advanced metal-oxygen batteries. State-of-the-art battery design principles for high-energy-density lithium-oxygen and sodium-oxygen batteries are thus reviewed in depth here. Major drawbacks, reaction mechanisms, and recent strategies to improve performance are also summarized. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Size Exclusion Chromatography Studies of the Initial Self-Association Steps of Chicken Egg White Lysozyme Nucleation

NASA Technical Reports Server (NTRS)

Ewing, Felecia; Donovan, David; Pusey, Marc

2000-01-01

Nucleation is one of the least understood aspects of crystallogenesis. In the case of macromolecule nucleation, this understanding is further hampered by uncertainty over what precisely is being discussed. We define the process of solute self-association (aggregation, oligomerization, interaction, clustering, etc.) whereby n-mers (n > or = 2) having a crystallographic or nascent crystallographic arrangement leading to the critical nucleus reversibly form in the solution, to be part of the nucleation process. This reversible self-association process is a fundamental part of the nucleation process, and occurs as a function of the solute concentration. In the case of chicken egg white lysozyme, a considerable body of experimental evidence leads us to the conclusion that it also forms the crystal growth units. Size exclusion chromatography is a simple and direct method for determining the equilibrium constants for the self-association process. A Pharmacia FPLC system was used to provide accurate solution flow rates. The column, injection valve, and sample loop were all mounted within a temperature-controlled chamber. Chromatographically re-purified lysozyme was first dialyzed against the column equilibration buffer, with injection onto the column after several hours pre-incubation at the running temperature. Preliminary experiments, were carried out using a Toyopearl HW-50F column (1 x 50cm), equilibrated with 0.1 M sodium acetate, 5% sodium chloride, pH 4.6, at 15C. Protein concentrations from 0.1 to 4 mg/ml were employed (C(sub sat) = 1.2 mg/ml). The data from several different protein preparations consistently shows a progressively decreasing elution volume with increasing protein concentration, indicating that reversible self-association is occurring. The dotted line indicates the monomeric lysozyme elution volume. However, lysozyme interacts with the column matrix in these experiments, which complicates data analysis.Accordingly, we are testing silica-based HPLC columns in an effort to eliminate this problem and substantially reduce the column volume and experimental run time. The results and data analysis from these and subsequent experiments will be presented.

STELLARATOR INJECTOR

DOEpatents

Post, R.F.

1962-09-01

A method and means are described for injecting energetic neutral atoms or molecular ions into dense magnetically collimated plasma columns of stellarators and the like in such a manner that the atoms or ions are able to significantly penetrate the column before being ionized by collision with the plasma constituent particles. Penetration of the plasma column by the neutral atoms or molecular ions is facilitated by superposition of two closely spaced magnetic mirrors on the plasma confinement field. The mirrors are moved apart to magnetically sweep plasma from a region between the mirrors and establish a relatively low plasma density therein. By virture of the low density, neutral atoms or molecular ions injected into the region significantly penetrate the plasma column before being ionized. Thereafter, the mirrors are diminished to permit the injected material to admix with the plasma in the remainder of the column. (AEC)

Study of scattering cross section of a plasma column using Green's function volume integral equation method

NASA Astrophysics Data System (ADS)

Soltanmoradi, Elmira; Shokri, Babak

2017-05-01

In this article, the electromagnetic wave scattering from plasma columns with inhomogeneous electron density distribution is studied by the Green's function volume integral equation method. Due to the ready production of such plasmas in the laboratories and their practical application in various technological fields, this study tries to find the effects of plasma parameters such as the electron density, radius, and pressure on the scattering cross-section of a plasma column. Moreover, the incident wave frequency influence of the scattering pattern is demonstrated. Furthermore, the scattering cross-section of a plasma column with an inhomogeneous collision frequency profile is calculated and the effect of this inhomogeneity is discussed first in this article. These results are especially used to determine the appropriate conditions for radar cross-section reduction purposes. It is shown that the radar cross-section of a plasma column reduces more for a larger collision frequency, for a relatively lower plasma frequency, and also for a smaller radius. Furthermore, it is found that the effect of the electron density on the scattering cross-section is more obvious in comparison with the effect of other plasma parameters. Also, the plasma column with homogenous collision frequency can be used as a better shielding in contrast to its inhomogeneous counterpart.

Liquid-chromatographic analysis for cyclosporine with use of a microbore column and small sample volume.

PubMed

Annesley, T; Matz, K; Balogh, L; Clayton, L; Giacherio, D

1986-07-01

This liquid-chromatographic assay requires 0.2 to 0.5 mL of whole blood, avoids the use of diethyl ether, and consumes only 10 to 20% of the solvents used in prior methods. Sample preparation involves an acidic extraction with methyl-t-butyl ether, performed in a 13 X 100 mm disposable glass tube, then a short second extraction of the organic phase with sodium hydroxide. After evaporation of the methyl-t-butyl ether, chromatography is performed on an "Astec" 2.0-mm (i.d.) octyl column. We compared results by this procedure with those by use of earlier larger-scale extractions and their respective 4.6-mm (i.d.) columns; analytical recoveries of cyclosporins A and D were comparable with previous findings and results for patients' specimens were equivalent, but the microbore columns provided greatly increased resolution and sensitivity.

Eagle-Picher Industries Sodium Sulfur Program

NASA Technical Reports Server (NTRS)

Silvey, Ronald L.

1993-01-01

Viewgraphs of the sodium sulfur program are presented. Sodium sulfur low earth orbit (LEO) cells are described. Topics covered include cell sizes, areas of improvement, and NaS cell testing. Sodium sulfur cell and battery designs continue to evolve with significant improvement demonstrated in resistance, rechargeability, cycle life, energy density, and electrolyte characterization.

Method of separating thorium from plutonium

DOEpatents

Clifton, David G.; Blum, Thomas W.

1984-01-01

A method of chemically separating plutonium from thorium. Plutonium and thorium to be separated are dissolved in an aqueous feed solution, preferably as the nitrate salts. The feed solution is acidified and sodium nitrite is added to the solution to adjust the valence of the plutonium to the +4 state. A chloride salt, preferably sodium chloride, is then added to the solution to induce formation of an anionic plutonium chloride complex. The anionic plutonium chloride complex and the thorium in solution are then separated by ion exchange on a strong base anion exchange column.

Method of separating thorium from plutonium

DOEpatents

Clifton, D.G.; Blum, T.W.

A method of chemically separating plutonium from thorium is claimed. Plutonium and thorium to be separated are dissolved in an aqueous feed solution, preferably as the nitrate salts. The feed solution is acidified and sodium nitrite is added to the solution to adjust the valence of the plutonium to the +4 state. A chloride salt, preferably sodium chloride, is then added to the solution to induce formation of an anionic plutonium chloride complex. The anionic plutonium chloride complex and the thorium in solution are then separated by ion exchange on a strong base anion exchange column.

Method of separating thorium from plutonium

DOEpatents

Clifton, D.G.; Blum, T.W.

1984-07-10

A method is described for chemically separating plutonium from thorium. Plutonium and thorium to be separated are dissolved in an aqueous feed solution, preferably as the nitrate salts. The feed solution is acidified and sodium nitrite is added to the solution to adjust the valence of the plutonium to the +4 state. A chloride salt, preferably sodium chloride, is then added to the solution to induce formation of an anionic plutonium chloride complex. The anionic plutonium chloride complex and the thorium in solution are then separated by ion exchange on a strong base anion exchange column.

Separation of flavonol-2-O-glycosides from Calendula officinalis and Sambucus nigra by high-performance liquid and micellar electrokinetic capillary chromatography.

PubMed

Pietta, P; Bruno, A; Mauri, P; Rava, A

1992-02-28

Calendula officinalis and Sambucus nigra flowers were analysed by reversed-phase high-performance liquid chromatography (RP-HPLC) and micellar electrokinetic capillary chromatography (MECC). RP-HPLC was performed on C8 Aquapore RP 300 columns with eluents containing 2-propanol and tetrahydrofuran. MECC was carried out on a 72-cm fused-silica capillary using sodium dodecyl sulphate and sodium borate (pH 8.3) as the running buffer. The results obtained by these techniques are compared.

Temporal and spatial distribution of metallic species in the upper atmosphere

NASA Astrophysics Data System (ADS)

Correira, John Thomas

2009-06-01

Every day the Earth is bombarded by approximately 100 tons of meteoric material. Much of this material is completely ablated on atmospheric entry, resulting in a layer of atomic metals in the upper atmosphere between 70 km - 150 km. These neutral atoms are ionized by solar radiation and charge exchange. Metal ions have a long lifetime against recombination loss, allowing them to be redistributed globally by electromagnetic forces, especially when lifted to altitudes >150 km. UV radiances from the Global Ozone Monitoring Experiment (GOME) spectrometer are used to determine long-term dayside variations of the total vertical column density below 795 km of the meteoric metal species Mg and Mg + in the upper atmosphere. A retrieval algorithm developed to determine magnesium column densities was applied to all available data from the years 1996-2001. Long term results show middle latitude dayside Mg + peaks in vertical content during the summer, while neutral Mg demonstrates a much more subtle maximum in summer. Atmospheric metal concentrations do not correlate strongly solar activity. An analysis of spatial variations shows geospatial distributions are patchy, with local regions of increased column density. To study short term variations and the role of meteor showers a time dependent mass flux rate is calculated using published estimates of meteor stream mass densities and activity profiles. An average daily mass flux rate is also calculated and used as a baseline against which shower mass flux rates are compared. These theoretical mass flux rates are then compared with GOME derived metal column densities. There appears to be little correlation between modeled meteor shower mass flux rates and changes in the observed neutral magnesium and Mg + metal column densities.

Temperature as a third dimension in column-density mapping of dusty astrophysical structures associated with star formation

NASA Astrophysics Data System (ADS)

Marsh, K. A.; Whitworth, A. P.; Lomax, O.

2015-12-01

We present point process mapping (PPMAP), a Bayesian procedure that uses images of dust continuum emission at multiple wavelengths to produce resolution-enhanced image cubes of differential column density as a function of dust temperature and position. PPMAP is based on the generic `point process formalism, whereby the system of interest (in this case, a dusty astrophysical structure such as a filament or pre-stellar core) is represented by a collection of points in a suitably defined state space. It can be applied to a variety of observational data, such as Herschel images, provided only that the image intensity is delivered by optically thin dust in thermal equilibrium. PPMAP takes full account of the instrumental point-spread functions and does not require all images to be degraded to the same resolution. We present the results of testing using simulated data for a pre-stellar core and a fractal turbulent cloud, and demonstrate its performance with real data from the Herschel infrared Galactic Plane Survey (Hi-GAL). Specifically, we analyse observations of a large filamentary structure in the CMa OB1 giant molecular cloud. Histograms of differential column density indicate that the warm material (T ≳ 13 K) is distributed lognormally, consistent with turbulence, but the column densities of the cooler material are distributed as a high-density tail, consistent with the effects of self-gravity. The results illustrate the potential of PPMAP to aid in distinguishing between different physical components along the line of sight in star-forming clouds, and aid the interpretation of the associated Probability distribution functions (PDFs) of column density.

Coupled Leidenfrost states as a monodisperse granular clock

NASA Astrophysics Data System (ADS)

Liu, Rui; Yang, Mingcheng; Chen, Ke; Hou, Meiying; To, Kiwing

2016-08-01

Using an event-driven molecular dynamics simulation, we show that simple monodisperse granular beads confined in coupled columns may oscillate as a different type of granular clock. To trigger this oscillation, the system needs to be driven against gravity into a density-inverted state, with a high-density clustering phase supported from below by a gaslike low-density phase (Leidenfrost effect) in each column. Our analysis reveals that the density-inverted structure and the relaxation dynamics between the phases can amplify any small asymmetry between the columns, and lead to a giant oscillation. The oscillation occurs only for an intermediate range of the coupling strength, and the corresponding phase diagram can be universally described with a characteristic height of the density-inverted structure. A minimal two-phase model is proposed and a linear stability analysis shows that the triggering mechanism of the oscillation can be explained as a switchable two-parameter Andronov-Hopf bifurcation. Numerical solutions of the model also reproduce similar oscillatory dynamics to the simulation results.

ZERO-VALENT IRON FOR HIGH-LEVEL ARSENITE REMOVAL

EPA Science Inventory

This study conducted by flow through column systems was aimed at investigating the feasibility of using zero-valent iron for arsenic remediation in groundwater. A high concentration arsenic solution (50 mg l-1) was prepared by using sodium arsenite (arsenic (III)) to simulate gr...

Rapid determination of minoxidil in human plasma using ion-pair HPLC.

PubMed

Zarghi, A; Shafaati, A; Foroutan, S M; Khoddam, A

2004-10-29

A rapid, simple and sensitive ion-pair high-performance liquid chromatography (HPLC) method has been developed for quantification of minoxidil in plasma. The assay enables the measurement of minoxidil for therapeutic drug monitoring with a minimum detectable limit of 0.5 ng ml(-1). The method involves simple, one-step extraction procedure and analytical recovery was complete. The separation was performed on an analytical 150 x 4.6 mm i.d. microbondapak C18 column. The wavelength was set at 281 nm. The mobile phase was a mixture of 0.01 M sodium dihydrogen phosphate buffer and acetonitrile (60:40, v/v) containing 2.5 mM sodium dodecyl sulphate adjusted to pH 3.5 at a flow rate of 1 ml/min. The column temperature was set at 50 degrees C. The calibration curve was linear over the concentration range 2-100 ng ml(-1). The coefficients of variation for inter-day and intra-day assay were found to be less than 8%.

Interactions of lectins with plasma membrane glycoproteins of the Ehrlich ascites carcinoma cell.

PubMed

Nachbar, M S; Oppenheim, J D; Aull, F

1976-02-06

Several aspects of the interaction of various lectins with the surface of Ehrlich ascites carcinoma cells are described. The order of agglutinating activity for various lectins is Ricinus communis greater than wheat germ greater than or equal to concanavalin A greater than or equal to soybean greater than Limulus polyphemus. No agglutination was noted for Ulex europaeus. Using 125I-labeled lectins it was determined that there are 1.6 and 7 times as many Ricinus communis lectin binding sites for concanavalin A and soybean lectins. Sodium deoxycholate-solubilized plasma membrane material was subjected to lectin affinity chromatography and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The lectin receptors of the plasma membrane appeared to be heterogeneous and some qualitative differences could be discerned among the electrophoretically analyzed material, which bound to and was specifically eluted from the various lectin affinity columns. The characteristics of elution of bound material from individual lectin columns indicated secondary hydrophobic interactions between concanavalin A or wheat germ agglutinin and their respective lectin receptor molecules.

Multiply Reduced Oligofluorenes: Their Nature and Pairing with THF-Solvated Sodium Ions

DOE PAGES

Wu, Qin; Zaikowski, Lori; Kaur, Parmeet; ...

2016-07-01

Conjugated oligofluorenes are chemically reduced up to five charges in tetrahydrofuran solvent and confirmed with clear spectroscopic evidence. Stimulated by these experimental results, we have conducted a comprehensive computational study of the electronic structure and the solvation structure of representative oligofluorene anions with a focus on the pairing between sodium ions and these multianions. In addition, using density functional theory (DFT) methods and a solvation model of both explicit solvent molecules and implicit polarizable continuum, we first elucidate the structure of tightly solvated free sodium ions, and then explore the pairing of sodium ions either in contact with reduced oligofluorenesmore » or as solvent-separated ion pairs. Computed time-dependent-DFT absorption spectra are compared with experiments to assign the dominant ion pairing structure for each multianion. Computed ion pair binding energies further support our assignment. Lastly, the availability of different length and reducing level of oligofluorenes enables us to investigate the effects of total charge and charge density on the binding with sodium ions, and our results suggest both factors play important roles in ion pairing for small molecules. However, as the oligofluorene size grows, its charge density determines the binding strength with the sodium ion.« less

US Food Industry Progress During the National Salt Reduction Initiative: 2009-2014.

PubMed

Curtis, Christine J; Clapp, Jenifer; Niederman, Sarah A; Ng, Shu Wen; Angell, Sonia Y

2016-10-01

To assess the US packaged food industry's progress from 2009 to 2014, when the National Salt Reduction Initiative had voluntary, category-specific sodium targets with the goal of reducing sodium in packaged and restaurant foods by 25% over 5 years. Using the National Salt Reduction Initiative Packaged Food Database, we assessed target achievement and change in sales-weighted mean sodium density in top-selling products in 61 food categories in 2009 (n = 6336), 2012 (n = 6898), and 2014 (n = 7396). In 2009, when the targets were established, no categories met National Salt Reduction Initiative 2012 or 2014 targets. By 2014, 26% of categories met 2012 targets and 3% met 2014 targets. From 2009 to 2014, the sales-weighted mean sodium density declined significantly in almost half of all food categories (43%; 26/61 categories). Overall, sales-weighted mean sodium density declined significantly (by 6.8%; P < .001). National target setting with monitoring through a partnership of local, state, and national health organizations proved feasible, but industry progress was modest. The US Food and Drug Administration's proposed voluntary targets will be an important step in achieving more substantial sodium reductions.

A magnesium–sodium hybrid battery with high operating voltage

DOE PAGES

Dong, Hui; Li, Yifei; Liang, Yanliang; ...

2016-06-10

Here, we report a high performance magnesium-sodium hybrid battery utilizing a magnesium-sodium dual-salt electrolyte, a magnesium anode, and a Berlin green cathode. The cell delivers an average discharge voltage of 2.2 V and a reversible capacity of 143 mA h g –1. We also demonstrate the cell with an energy density of 135 W h kg –1 and a high power density of up to 1.67 kW kg –1.

Satellite Investigation of Atmospheric Metal Deposition During Meteor Showers

NASA Astrophysics Data System (ADS)

Correira, J.; Aikin, A. C.; Grebowsky, J. M.

2008-12-01

Using the nadir-viewing Global Ozone Measuring Experiment (GOME) UV/VIS spectrometer on the ERS-2 satellite, we investigate short term variations in the magnesium column densities and any connection to possible enhanced mass deposition during a meteor shower. We derive a time dependent mass flux rate due to meteor showers using published estimates of mass density and activity profiles of meteor showers. An average daily mass flux rate is also calculated and used as a baseline against which calculated shower mass flux rates are compared. These theoretical mass flux rates are then compared with GOME derived metal column densities from the years 1996 - 2001.There appears to be little correlation between theoretical mass flux rates and changes in the Mg and Mg+ metal column densities. A possible explanation for the lack of a shower related increase in metal concentrations may be differences in the mass regimes dominating the average background mass flux and shower mass flux.

Effects of Coulomb collisions on cyclotron maser and plasma wave growth in magnetic loops

NASA Technical Reports Server (NTRS)

Hamilton, Russell J.; Petrosian, Vahe

1990-01-01

The evolution of nonthermal electrons accelerated in magnetic loops is determined by solving the kinetic equation, including magnetic field convergence and Coulomb collisions in order to determine the effects of these interactions on the induced cyclotron maser and plasma wave growth. It is found that the growth rates are larger and the possibility of cyclotron maser action is stronger for smaller loop column density, for larger magnetic field convergence, for a more isotropic injected electron pitch angle distribution, and for more impulsive acceleration. For modest values of the column density in the coronal portion of a flaring loop, the growth rates of instabilities are significantly reduced, and the reduction is much larger for the cyclotron modes than for the plasma wave modes. The rapid decrease in the growth rates with increasing loop column density suggests that, in flare loops when such phenomena occur, the densities are lower than commonly accepted.

Long-term study of longitudinal dependence in primary particle precipitation in the north Jovian aurora

NASA Technical Reports Server (NTRS)

Livengood, T. A.; Strobel, D. F.; Moos, H. W.

1990-01-01

The wavelength-dependent absorption apparent in IUE spectra of the north Jovian aurora is analyzed to determine the column density of hydrocarbons above the altitude of the FUV auroral emission. Both the magnetotail and torus auroral zone models are considered in estimating zenith angles, with very similar results obtained for both models. It is found that the hydrocarbon column density above the FUV emission displays a consistent dependence on magnetic longitude, with the peak density occurring approximately coincident with the peak in the observed auroral intensity. Two distinct scenarios for the longitude dependence of the column density are discussed. In one, the Jovian upper atmosphere is longitudinally homogeneous, and the variation in optical depth is due to a variation in penetration, and thus energy, of the primary particles. In the other, the energy of the primaries is longitudinally homogeneous, and it is aeronomic properties which change, probably due to auroral heating.

The Zone of Avoidance as an X-ray absorber - the role of the galactic foreground modelling Swift XRT spectra

NASA Astrophysics Data System (ADS)

Racz, I. I.; Bagoly, Z.; Tóth, L. V.; Balázs, L. G.; Horvath, I.; Zahorecz, S.

2018-05-01

Gamma-ray bursts (GRBs) are the most powerful explosive events in the Universe. The prompt gamma emission is followed by an X-ray afterglow that is also detected for over nine hundred GRBs by the Swift BAT and XRT detectors. The X-ray afterglow spectrum bears essential information about the burst, and the surrounding interstellar medium (ISM). Since the radiation travels through the line of sight intergalactic medium and the ISM in the Milky Way, the observed emission is influenced by extragalactic and galactic components. The column density of the Galactic foreground ranges several orders of magnitudes, due to both the large scale distribution of ISM and its small scale structures. We examined the effect of local HI column density on the penetrating X-ray emission, as the first step towards a precise modeling of the measured X-ray spectra. We fitted the X-ray spectra using the Xspec software, and checked how the shape of the initially power low spectrum changes with varying input Galactic HI column density. The total absorbing HI column is a sum of the intrinsic and Galactic component. We also investigated the model results for the intrinsic component varying the Galactic foreground. We found that such variations may alter the intrinsic hydrogen column density up to twenty-five percent. We will briefly discuss its consequences.

Use of emulsified vegetable oil to support bioremediation of TCE DNAPL in soil columns.

PubMed

Harkness, Mark; Fisher, Angela

2013-08-01

The interaction between emulsified vegetable oil (EVO) and trichloroethylene (TCE) dense non-aqueous phase liquid (DNAPL) was observed using two soil columns and subsequent reductive dechlorination of TCE was monitored over a three year period. Dyed TCE DNAPL (~75 g) was emplaced in one column (DNAPL column), while the second was DNAPL-free (plume column). EVO was added to both columns and partitioning of the EVO into the TCE DNAPL was measured and quantified. TCE (1.9 mM) was added to the influent of the plume column to simulate conditions down gradient of a DNAPL source area and the columns were operated independently for more than one year, after which they were connected in series. Initially limited dechlorination of TCE to cDCE was observed in the DNAPL column, while the plume column supported complete reductive dechlorination of TCE to ethene. Upon connection and reamendment of the plume column with EVO, near saturation levels of TCE from the effluent of the DNAPL column were rapidly dechlorinated to c-DCE and VC in the plume column; however, this high rate dechlorination produced hydrochloric acid which overwhelmed the buffering capacity of the system and caused the pH to drop below 6.0. Dechlorination efficiency in the columns subsequently deteriorated, as measured by the chloride production and Dehalococcoides counts, but was restored by adding sodium bicarbonate buffer to the influent groundwater. Robust dechlorination was eventually observed in the DNAPL column, such that the TCE DNAPL was largely removed by the end of the study. Partitioning of the EVO into the DNAPL provided significant operational benefits to the remediation system both in terms of electron donor placement and longevity. Copyright © 2013 Elsevier B.V. All rights reserved.

Physical conditions in CaFe interstellar clouds

NASA Astrophysics Data System (ADS)

Gnaciński, P.; Krogulec, M.

2008-01-01

Interstellar clouds that exhibit strong Ca I and Fe I lines are called CaFe clouds. Ionisation equilibrium equations were used to model the column densities of Ca II, Ca I, K I, Na I, Fe I and Ti II in CaFe clouds. We find that the chemical composition of CaFe clouds is solar and that there is no depletion into dust grains. CaFe clouds have high electron densities, n_e≈1 cm-3, that lead to high column densities of neutral Ca and Fe.

The dependence of gamma-ray burst X-ray column densities on the model for Galactic hydrogen

NASA Astrophysics Data System (ADS)

Arcodia, R.; Campana, S.; Salvaterra, R.

2016-05-01

We study the X-ray absorption of a complete sample of 99 bright Swift gamma-ray bursts (GRBs). In recent years, a strong correlation has been found between the intrinsic X-ray absorbing column density (NH(z)) and the redshift. This absorption excess in high-z GRBs is now thought to be due to the overlooked contribution of the absorption along the intergalactic medium (IGM), by means of both intervening objects and the diffuse warm-hot intergalactic medium along the line of sight. In this work we neglect the absorption along the IGM, because our purpose is to study the eventual effect of a radical change in the Galactic absorption model on the NH(z) distribution. Therefore, we derive the intrinsic absorbing column densities using two different Galactic absorption models: the Leiden Argentine Bonn HI survey and the more recent model that includes molecular hydrogen. We find that if, on the one hand, the new Galactic model considerably affects the single column density values, on the other hand, there is no drastic change in the distribution as a whole. It becomes clear that the contribution of Galactic column densities alone, no matter how improved, is not sufficient to change the observed general trend and it has to be considered as a second order correction. The cosmological increase of NH(z) as a function of redshift persists and, to explain the observed distribution, it is necessary to include the contribution of both the diffuse intergalactic medium and the intervening systems along the line of sight of the GRBs.

Global distribution of the He+ column density observed by Extreme Ultra Violet Imager on the International Space Station

NASA Astrophysics Data System (ADS)

Hozumi, Yuta; Saito, Akinori; Yoshikawa, Ichiro; Yamazaki, Atsushi; Murakami, Go; Yoshioka, Kazuo; Chen, Chia-Hung

2017-07-01

The global distribution of He+ in the topside ionosphere was investigated using data of the He+ resonant scattering emission at 30.4 nm obtained by the Extreme Ultra Violet Imager (EUVI) onboard the International Space Station. The optical observation by EUVI from the low-Earth orbit provides He+ column density data above the altitude of 400 km, presenting a unique opportunity to study the He+ distribution with a different perspective from that of past studies using data from in situ measurements. We analyzed data taken in 2013 and elucidated, for the first time, the seasonal, longitudinal, and latitudinal variations of the He+ column density in the dusk sector. It was found that the He+ column density in the winter hemisphere was about twice that in the summer hemisphere. In the December solstice season, the magnitude of this hemispheric asymmetry was large (small) in the longitudinal sector where the geomagnetic declination is eastward (westward). In the June solstice season, this relationship between the He+ distribution and the geomagnetic declination is reversed. In the equinox seasons, the He+ column densities in the two hemispheres are comparable at most longitudes. The seasonal and longitudinal dependence of the hemispheric asymmetry of the He+ distribution was attributed to the geomagnetic meridional neutral wind in the F region ionosphere. The neutral wind effect on the He+ distribution was examined with an empirical neutral wind model, and it was confirmed that the transport of ions in the topside ionosphere is predominantly affected by the F region neutral wind and the geomagnetic configuration.

Stochastic Accumulation by Cortical Columns May Explain the Scalar Property of Multistable Perception

NASA Astrophysics Data System (ADS)

Cao, Robin; Braun, Jochen; Mattia, Maurizio

2014-08-01

The timing of certain mental events is thought to reflect random walks performed by underlying neural dynamics. One class of such events—stochastic reversals of multistable perceptions—exhibits a unique scalar property: even though timing densities vary widely, higher moments stay in particular proportions to the mean. We show that stochastic accumulation of activity in a finite number of idealized cortical columns—realizing a generalized Ehrenfest urn model—may explain these observations. Modeling stochastic reversals as the first-passage time of a threshold number of active columns, we obtain higher moments of the first-passage time density. We derive analytical expressions for noninteracting columns and generalize the results to interacting columns in simulations. The scalar property of multistable perception is reproduced by a dynamic regime with a fixed, low threshold, in which the activation of a few additional columns suffices for a reversal.

Numerical modeling of the elution peak profiles of retained solutes in supercritical fluid chromatography

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kaczmarski, Krzysztof; Guiochon, Georges A

2011-01-01

In supercritical fluid chromatography (SFC), the significant expansion of the mobile phase along the column causes the formation of axial and radial gradients of temperature. Due to these gradients, the mobile phase density, its viscosity, its velocity, its diffusion coefficients, etc. are not constant throughout the column. This results in a nonuniform flow velocity distribution, itself causing a loss of column efficiency in certain cases, even at low flow rates, as they do in HPLC. At high flow rates, an important deformation of the elution profiles of the sample components may occur. The model previously used to account satisfactorily formore » the retention of an unsorbed solute in SFC is applied to the modeling of the elution peak profiles of retained compounds. The numerical solution of the combined heat and mass balance equations provides the temperature and the pressure profiles inside the column and values of the retention time and the band profiles of retained compounds that are in excellent agreement with independent experimental data for large value of mobile phase reduced density. At low reduced densities, the band profiles can strongly depend on the column axial distribution of porosity.« less

Decaying toxic wood as sodium supplement for herbivorous mammals in Gabon.

PubMed

Iwata, Yuji; Nakashima, Yoshihiro; Tsuchida, Sayaka; Nguema, Pierre Philippe Mbehang; Ando, Chieko; Ushida, Kazunari; Yamagiwa, Juichi

2015-10-01

African rainforest harbors herbivores at high density. However, because plants and soils typically lack in some essential minerals, rainforest is not always a suitable habitat for herbivores. How they fulfill the mineral requirements is therefore an important question to animal ecology and conservation. Although large marshes, called 'bais', are often mentioned as efficient mineral-resource, little information on other sodium resources has still been available. Our laboratory works and field surveys found that a peculiar item, decaying wood stumps of Anthostema aubryanum, played as a major sodium resource for herbivores in Moukalaba-Doudou National Park, Gabon. When A. aubryanum is alive, the sodium content of its bark is low and its latex is toxic. Sodium is accumulated in decaying stumps (mean=1,343 mg/kg dry matter). Eight herbivores visited stumps to ingest the dead wood. Fecal sample analysis revealed that western lowland gorillas, a species most-frequently using the stumps, consumed large amount of the dead wood as regular food. Our findings suggest that decaying A. aubryanum is critical sodium-resources and is a key species for herbivores in our study area. Importance of the A. aubryanum may be particularly large there, because it is a limited sodium-rich material that is available year round. Our study site is known as the site where the densities of several herbivores are among the highest at Central Africa. The relatively high herbivores density in our study site may partly depend on decaying A. aubryanum as sodium resources.

CO Column Density and Extinction in the Chamaeleon II--III Dark-Cloud Complex

NASA Astrophysics Data System (ADS)

Hayakawa, Takahiro; Cambrésy, Laurent; Onishi, Toshikazu; Mizuno, Akira; Fukui, Yasuo

2001-12-01

We carried out 13CO (J = 1 -- 0) and C18O (J = 1 -- 0) observations of the Chamaeleon II--III dark-cloud complex with the NANTEN radio telescope. The column densities of both molecular isotopes were derived assuming LTE. The AV values were obtained by scaling the AV values that were derived using an adaptive-grid star-count method applied to the DENIS J-band data. We established the AV--CO isotope column-density relations in Cha II and III, and compared them with those in Cha I. The slopes of the AV--13CO relations for Cha II and III are steeper than that for Cha I. Those of the AV -- C18O relations are similar among the three clouds. The total column density ratio, N(13O) / N(C18O, in Cha I tends to be small compared with those in Cha II or Cha III; the ratios range from ~ 5 to ~ 25 at low extinction in Cha II and III, but at most ~ 10 in Cha I. We suggest that the increase of N(13CO) due to the 13CO formation process causes cloud-to-cloud variations in the AV -- N(13CO) correlation.

New Theoretical Model of Nerve Conduction in Unmyelinated Nerves

PubMed Central

Akaishi, Tetsuya

2017-01-01

Nerve conduction in unmyelinated fibers has long been described based on the equivalent circuit model and cable theory. However, without the change in ionic concentration gradient across the membrane, there would be no generation or propagation of the action potential. Based on this concept, we employ a new conductive model focusing on the distribution of voltage-gated sodium ion channels and Coulomb force between electrolytes. Based on this new model, the propagation of the nerve conduction was suggested to take place far before the generation of action potential at each channel. We theoretically showed that propagation of action potential, which is enabled by the increasing Coulomb force produced by inflowing sodium ions, from one sodium ion channel to the next sodium channel would be inversely proportionate to the density of sodium channels on the axon membrane. Because the longitudinal number of sodium ion channel would be proportionate to the square root of channel density, the conduction velocity of unmyelinated nerves is theoretically shown to be proportionate to the square root of channel density. Also, from a viewpoint of equilibrium state of channel importation and degeneration, channel density was suggested to be proportionate to axonal diameter. Based on these simple basis, conduction velocity in unmyelinated nerves was theoretically shown to be proportionate to the square root of axonal diameter. This new model would also enable us to acquire more accurate and understandable vision on the phenomena in unmyelinated nerves in addition to the conventional electric circuit model and cable theory. PMID:29081751

3.0 V High Energy Density Symmetric Sodium-Ion Battery: Na4V2(PO4)3∥Na3V2(PO4)3.

PubMed

Yao, Xuhui; Zhu, Zixuan; Li, Qi; Wang, Xuanpeng; Xu, Xiaoming; Meng, Jiashen; Ren, Wenhao; Zhang, Xinhe; Huang, Yunhui; Mai, Liqiang

2018-03-28

Symmetric sodium-ion batteries (SIBs) are considered as promising candidates for large-scale energy storage owing to the simplified manufacture and wide abundance of sodium resources. However, most symmetric SIBs suffer from suppressed energy density. Here, a superior congeneric Na 4 V 2 (PO 4 ) 3 anode is synthesized via electrochemical preintercalation, and a high energy density symmetric SIB (Na 3 V 2 (PO 4 ) 3 as a cathode and Na 4 V 2 (PO 4 ) 3 as an anode) based on the deepened redox couple of V 4+ /V 2+ is built for the first time. When measured in half cell, both electrodes show stabilized electrochemical performance (over 3000 cycles). The symmetric SIBs exhibit an output voltage of 3.0 V and a cell-level energy density of 138 W h kg -1 . Furthermore, the sodium storage mechanism under the expanded measurement range of 0.01-3.9 V is disclosed through an in situ X-ray diffraction technique.

Bias and uncertainty in the absorption emission measurement of atomic sodium density in the SSME exit plane

NASA Technical Reports Server (NTRS)

Bauman, Leslie E.

1990-01-01

The measurement of atomic sodium concentration in the TTB 019 firing of April 1990 is significant in that it represents the first measurement of density at the exit plane of the space shuttle main engine. The knowledge of the sodium density, combined with the certainty that the exit plane of the plume is optically thin at the sodium D-line wavelengths, provides essential information for evaluation of diagnostic techniques using sodium atoms, such as resonant Doppler velocimetry for temperature, pressure, and velocity through high resolution fluorescent lineshape analysis. The technique used for the sodium atom line transmission (SALT) measurements is that of resonant absorption emission using a hollow cathode lamp as the reference source. Through the use of two-dimensional kinetic (TDK) predictions of temperature and density for the flight engine case and radiative transfer calculations, this line-of-sight spectrally integrated transmission indicates a sodium atom concentration, i.e., mole fraction, of 0.91e-10. The subject of this paper is the assumptions and measurement uncertainties tied into the calculation. Because of the narrow shape of the source emission, the uncertainties in the absorption profile could introduce considerable bias in the measurement. The following were investigated: (1) the inclusion of hyperfine splitting of the D-lines in the calculation; (2) the use of the flight engine predictions of plume temperature and density versus those for the large throat engine; (3) the assumption of a Gaussian, i.e., Doppler, distribution for the source radiance with a temperature of 400 K; (4) the use of atomic collisional shift and width values for the work by Jongerius; and (5) a Doppler shift for a 7 degree outward velocity vector at the plume edge. Also included in the study was the bias introduced by an uncertainty in the measurement of the D1/D2 line ratio in the source.

Spectrofluorometry, thin layer chromatography, and column high-performance liquid chromatography determination of rabeprazole sodium in the presence of its acidic and oxidized degradation products.

PubMed

Osman, Afaf Osman; Osman, Afaf; Osman, Mohamed

2009-01-01

The objective of this study is to develop validated stability-indicating spectrofluorometric, TLC-densitometric, and HPLC methods for the determination of rabeprazole sodium and its degradation products. The first method was based on measuring the fluorescence intensity of the drug at 416 and 311 nm for the emission and at 320 and 274 nm for the excitation for acid and oxidized solutions, respectively. The second method was based on the separation of the drug from its acidic and oxidized degradation products followed by densitometric measurement of the intact drug spot at 284 nm. The separation was carried out on Fluka TLC sheets of silica gel 60 F254 using isopropyl alcohol--30% ammonia (80 + 2, v/v) mobile phase. The third method was based on HPLC separation of rabeprazole sodium from its acidic and oxidized degradation products on a reversed-phase Waters Nova-Pak C18 column using 0.05 M potassium dihydrogen phosphate-methanol-acetonitrile (5 + 3 + 2, v/v/v) pH 7 +/- 0.2 mobile phase. The proposed procedures were successfully applied for the determination of rabeprazole sodium in pure form, laboratory-prepared mixtures, tablet, and expired batch. The obtained results were statistically compared with those of a reported method and validated according to United States Pharmacopeia guidelines. Two main acidic degradation products of the drug were separated and subjected to IR spectrometry and MS to confirm their structures, and the schemes for their formation were elucidated.

Ultra high pressure liquid chromatography. Column permeability and changes of the eluent properties.

PubMed

Gritti, Fabrice; Guiochon, Georges

2008-04-11

The behavior of four similar liquid chromatography columns (2.1mm i.d. x 30, 50, 100, and 150 mm, all packed with fine particles, average d(p) approximately 1.7 microm, of bridged ethylsiloxane/silica hybrid-C(18), named BEH-C(18)) was studied in wide ranges of temperature and pressure. The pressure and the temperature dependencies of the viscosity and the density of the eluent (pure acetonitrile) along the columns were also derived, using the column permeabilities and applying the Kozeny-Carman and the heat balance equations. The heat lost through the external surface area of the chromatographic column was directly derived from the wall temperature of the stainless steel tube measured with a precision of +/-0.2 degrees C in still air and +/-0.1 degrees C in the oven compartment. The variations of the density and viscosity of pure acetonitrile as a function of the temperature and pressure was derived from empirical correlations based on precise experimental data acquired between 298 and 373 K and at pressures up to 1.5 kbar. The measurements were made with the Acquity UPLC chromatograph that can deliver a maximum flow rate of 2 mL/min and apply a maximum column inlet pressure of 1038 bar. The average Kozeny-Carman permeability constant of the columns was 144+/-3.5%. The temperature hence the viscosity and the density profiles of the eluent along the column deviate significantly from linear behavior under high-pressure gradients. For a 1000 bar pressure drop, we measured DeltaT=25-30 K, (Deltaeta/eta) approximately 100%, and (Deltarho/rho) approximately 10%. These results show that the radial temperature profiles are never fully developed within 1% for any of the columns, even under still-air conditions. This represents a practical advantage regarding the apparent column efficiency at high flow rates, since the impact of the differential analyte velocity between the column center and the column wall is not maximum. The interpretation of the peak profiles recorded in UPLC is discussed.

Variation of Lunar Sodium During Passage of the Moon through the Earth's Magnetotail

NASA Technical Reports Server (NTRS)

Potter, Andrew E.; Killen, Rosemary M.; Morgan, Thomas H.

2000-01-01

We measured sodium emission above the lunar equator over a range of lunar altitudes from 100 to 4000 km. The measurements were repeated approximately every 24 hours from June 7 to 16, 1998, covering the period during which the Moon passed through the Earth's magnetotail. Sodium temperatures derived from the altitude dependence of emission intensity ranged from 1200 to 2900 K. This result supports the view that photodesorption is a primary source of sodium in the exosphere since the most probable temperature of sodium form this source is in this range. Passage of the Moon through the Earth's magnetotail (where solar wind is essentially absent) affected the sodium density, such that it was higher before the Moon entered the Earth's magnetotail than after the Moon left it. This suggests that the solar wind plays a role in production of lunar sodium. We propose that its function is to mobilize sodium and bring it to the surface, where photodesorption can eject it into the exosphere. A two-step process such as this could help to explain the latitude dependence of sodium density, which varies as the second or higher power of cosine latitude.

Climatology of mesopause region nocturnal temperature, zonal wind, and sodium density observed by sodium lidar over Hefei, China (32°N, 117°E)

NASA Astrophysics Data System (ADS)

Li, T.; Ban, C.; Fang, X.; Li, J.; Wu, Z.; Xiong, J.; Feng, W.; Plane, J. M. C.

2017-12-01

The University of Science and Technology of China narrowband sodium temperature/wind lidar, located in Hefei, China (32°N, 117°E), was installed in November 2011 and have made routine nighttime measurements since January 2012. We obtained 154 nights ( 1400 hours) of vertical profiles of temperature, sodium density, and zonal wind, and 83 nights ( 800 hours) of vertical flux of gravity wave (GW) zonal momentum in the mesopause region (80-105 km) during the period of 2012 to 2016. In temperature, it is likely that the diurnal tide dominates below 100 km in spring, while the semidiurnal tide dominates above 100 km throughout the year. A clear semiannual variation in temperature is revealed near 90 km, likely related to the tropical mesospheric semiannual oscillation (MSAO). The variability of sodium density is positively correlated with temperature, suggesting that in addition to dynamics, the chemistry may also play an important role in the formation of sodium atoms. The observed sodium peak density is 1000 cm-3 higher than that simulated by the model. In zonal wind, the diurnal tide dominates in both spring and fall, while semidiurnal tide dominates in winter. The observed semiannual variation in zonal wind near 90 km is out-of-phase with that in temperature, consistent with tropical MSAO. The GW zonal momentum flux is mostly westward in fall and winter, anti-correlated with eastward zonal wind. The annual mean flux averaged over 87-97 km is -0.3 m2/s2 (westward), anti-correlated with eastward zonal wind of 10 m/s. The comparisons of lidar results with those observed by satellite, nearby radar, and simulated by model show generally good agreements.

Salt sensitivity in normotensives with family history of hypertension: studies of membrane transport, intracellular electrolytes and alpha 2-adrenergic receptors.

PubMed

Skrabal, F; Gruber, G; Meister, B; Ledochowski, M; Doll, P; Lang, F; Cerny, E

1985-12-01

Using long-term automatic blood pressure recording it has previously been shown that subjects with family history of hypertension show a minute fall of blood pressure during sodium restriction, which is reversible by high sodium intake. Thus normotensives with hypertensive antecedents as a group are salt-sensitive, whereas normotensives without heredity of hypertension as a group are salt-resistant. The present study compares intracellular sodium, potassium and calcium, sodium pump activity, NaK-cotransport of red blood cells and density and affinity of alpha 2-adrenergic receptors of platelets in normotensive subjects classified according to family history of hypertension and according to 'salt sensitivity' and 'salt resistance'. Neither the family history of hypertension nor salt sensitivity correlated with intracellular sodium, potassium, calcium, Na-pump activity and NaK-cotransport. Alpha 2-adrenergic density was higher in salt-sensitive than in salt-resistant subjects (P < 0.05) but similar in subjects with a positive and negative family history of hypertension. However, alpha 2-adrenergic receptor density decreased significantly during 2 weeks of moderate salt restriction from 169.6 +/- 34.2 to 142.6 +/- 30.8 (P < 0.01, paired t-test), which may explain the decreased pressor response to infused noradrenaline observed in a previous study during moderate salt restriction. It is concluded that in humans there is no association of genetic predisposition of hypertension or of salt sensitivity to an alteration of sodium pump activity, NaK-cotransport, intracellular sodium and calcium. Alpha 2-receptor density of platelets deserves further study as a possible predictor of salt sensitivity in normotensives.

Theoretical and lidar studies of the density response of the mesospheric sodium layer to gravity wave perturbations

NASA Technical Reports Server (NTRS)

Shelton, J. D.; Gardner, C. S.

1981-01-01

The density response of atmospheric layers to gravity waves is developed in two forms, an exact solution and a perturbation series solution. The degree of nonlinearity in the layer density response is described by the series solution whereas the exact solution gives insight into the nature of the responses. Density perturbation in an atmospheric layer are shown to be substantially greater than the atmospheric density perturbation associated with the propagation of a gravity wave. Because of the density gradients present in atmospheric layers, interesting effects were observed such as a phase reversal in the linear layer response which occurs near the layer peak. Once the layer response is understood, the sodium layer can be used as a tracer of atmospheric wave motions. A two dimensional digital signal processing technique was developed. Both spatial and temporal filtering are utilized to enhance the resolution by decreasing shot noise by more han 10 dB. Many of the features associated with a layer density response to gravity waves were observed in high resolution density profiles of the mesospheric sodium layer. These include nonlinearities as well as the phase reversal in the linear layer response.

Relationship between the column density distribution and evolutionary class of molecular clouds as viewed by ATLASGAL

NASA Astrophysics Data System (ADS)

Abreu-Vicente, J.; Kainulainen, J.; Stutz, A.; Henning, Th.; Beuther, H.

2015-09-01

We present the first study of the relationship between the column density distribution of molecular clouds within nearby Galactic spiral arms and their evolutionary status as measured from their stellar content. We analyze a sample of 195 molecular clouds located at distances below 5.5 kpc, identified from the ATLASGAL 870 μm data. We define three evolutionary classes within this sample: starless clumps, star-forming clouds with associated young stellar objects, and clouds associated with H ii regions. We find that the N(H2) probability density functions (N-PDFs) of these three classes of objects are clearly different: the N-PDFs of starless clumps are narrowest and close to log-normal in shape, while star-forming clouds and H ii regions exhibit a power-law shape over a wide range of column densities and log-normal-like components only at low column densities. We use the N-PDFs to estimate the evolutionary time-scales of the three classes of objects based on a simple analytic model from literature. Finally, we show that the integral of the N-PDFs, the dense gas mass fraction, depends on the total mass of the regions as measured by ATLASGAL: more massive clouds contain greater relative amounts of dense gas across all evolutionary classes. Appendices are available in electronic form at http://www.aanda.org

A search for interstellar pyrrole - Evidence that rings are less abundant than chains

NASA Technical Reports Server (NTRS)

Myers, P. C.; Thaddeus, P.; Linke, R. A.

1980-01-01

Searches for three transitions of pyrrole (C4H5N) give maximum column density = 3-10 x 10 to the 13th per sq cm in Sgr B2. This limit is more than 10 times lower than previous ring molecule limits, and is slightly lower than column densities of known interstellar molecules with from four to six heavy atoms.

Helical patterns of magnetization and magnetic charge density in iron whiskers

NASA Astrophysics Data System (ADS)

Templeton, Terry L.; Hanham, Scott D.; Arrott, Anthony S.

2018-05-01

Studies with the (1 1 1) axis along the long axis of an iron whisker, 40 years ago, showed two phenomena that have remained unexplained: 1) In low fields, there are six peaks in the ac susceptibility, separated by 0.2 mT; 2) Bitter patterns showed striped domain patterns. Multipole columns of magnetic charge density distort to form helical patterns of the magnetization, accounting for the peaks in the susceptibility from the propagation of edge solitons along the intersections of the six sides of a (1 1 1) whisker. The stripes follow the helices. We report micromagnetic simulations in cylinders with various geometries for the cross-sections from rectangular, to hexagonal, to circular, with wide ranges of sizes and lengths, and different anisotropies, including (0 0 1) whiskers and the hypothetical case of no anisotropy. The helical patterns have been there in previous studies, but overlooked. The surface swirls and body helices are connected, but have their own individual behaviors. The magnetization patterns are more easily understood when viewed observing the scalar divergences of the magnetization as isosurfaces of magnetic charge density. The plus and minus charge densities form columns that interact with unlike charges attracting, but not annihilating as they are paid for by a decrease in exchange energy. Just as they start to form the helix, the columns are multipoles. If one could stretch the columns, the self-energy of the charges in a column would be diminished while making the attractive interactions of the unlike charges larger. The columns elongate by becoming helical. The visualization of 3-D magnetic charge distributions aids in the understanding of magnetization in soft magnetic materials.

Chiral Compounds and Green Chemistry in Undergraduate Organic Laboratories: Reduction of a Ketone by Sodium Borohydride and Baker's Yeast

NASA Astrophysics Data System (ADS)

Pohl, Nicola; Clague, Allen; Schwarz, Kimberly

2002-06-01

We describe an integrated set of experiments for the undergraduate organic laboratory that allows students to compare and contrast biological and chemical means of introducing chirality into a molecule. The racemic reduction of ethyl acetoacetate with sodium borohydride and the same reduction in the presence of a tartaric acid ligand are described, and a capillary gas chromatography column packed with a chiral material for product analysis is introduced. The results of these two hydride reactions are compared with the results of a common undergraduate experiment, the baker's yeast reduction of ethyl acetoacetate.

Calibration of the Urbana lidar system

NASA Technical Reports Server (NTRS)

Cerny, T.; Sechrist, C. F., Jr.

1980-01-01

A method for calibrating data obtained by the Urban sodium lidar system is presented. First, an expression relating the number of photocounts originating from a specific altitude range to the soodium concentration is developed. This relation is then simplified by normalizing the sodium photocounts with photocounts originating from the Rayleigh region of the atmosphere. To evaluate the calibration expression, the laser linewidth must be known. Therefore, a method for measuring the laser linewidth using a Fabry-Perot interferometer is given. The laser linewidth was found to be 6 + or - 2.5 pm. Problems due to photomultiplier tube overloading are discussed. Finally, calibrated data is presented. The sodium column abundance exhibits something close to a sinusoidal variation throughout the year with the winter months showing an enhancement of a factor of 5 to 7 over the summer months.

Two new hot white dwarfs in a region of exceptionally low hi density

NASA Technical Reports Server (NTRS)

Barstow, M. A.; Wesemael, F.; Holberg, J. B.; Werner, K.; Buckley, D. A. H.; Stobie, R. S.; Fontaine, G.; Rosen, S. R.; Demers, S.; Lamontagne, R.

1993-01-01

We report the discovery of two hot white dwarfs which have the lowest line-of-sight neutral hydrogen column densities yet measured. The stars were found independently by the ROSAT EUV, Montreal-Cambridge-Tololo, and Edinburgh-Cape surveys. Follow-up observations made using the Voyager 2 ultraviolet spectrometer reveal strong continua shortward of the 912A Lyman limit from which we deduce that the neutral hydrogen column densities are 1.3 x 10(exp 17) and 2.0 x 10(exp 17) atoms/sq cm.

Observational discrimination between modes of shock propagation in interstellar clouds: Predictions of CH+ and SH+ column densities in diffuse clouds

NASA Technical Reports Server (NTRS)

Flower, D. R.; Desforets, G. P.; Roueff, E.; Hartquist, T. W.

1986-01-01

Considerable effort in recent years has been devoted to the study of shocks in the diffuse interstellar medium. This work has been motivated partly by the observations of rotationally excited states of H2, and partly by the realization that species such as CH(+), OH and H2O might be formed preferentially in hot, post-shock gas. The problem of CH(+) and the difficulties encountered when trying to explain the high column densities, observed along lines of sight to certain hot stars, have been reviewed earlier. The importance of a transverse magnetic field on the structure of an interstellar shock was also demonstrated earlier. Transverse magnetic fields above a critical strength give rise to an acceleration zone or precursor, in which the parameters on the flow vary continuously. Chemical reactions, which change the degree of ionization of the gas, also modify the structure of the shock considerably. Recent work has shown that large column densities of CH(+) can be produced in magnetohydrodynamic shock models. Shock speeds U sub s approx. = 10 km/s and initial magnetic field strengths of a few micro G are sufficient to produce ion-neutral drift velocities which can drive the endothermic C(+)(H2,H)CH(+) reaction. It was also shown that single-fluid hydrodynamic models do not generate sufficiently large column densities of CH(+) unless unacceptably high shock velocities (u sub s approx. 20 km/s) are assumed in the models. Thus, the observed column densities of CH(+) provide a constraint on the mode of shock propagation in diffuse clouds. More precisely, they determine a lower limit to the ion-neutral drift velocity.

40 CFR 98.398 - Definitions.

Code of Federal Regulations, 2010 CFR

2010-07-01

... GREENHOUSE GAS REPORTING Suppliers of Petroleum Products § 98.398 Definitions. All terms used in this subpart... MM-1 Table MM-1 to Subpart MM of Part 98—Default Factors for Petroleum Products and Natural Gas Liquids 1 2 Products Column A: density(metric tons/bbl) Column B:carbon share (% of mass) Column C...

The Far-Infrared Spectrum of Arp 220

NASA Technical Reports Server (NTRS)

Gonzalez-Alfonso, Eduardo; Smith, Howard A.; Fischer, Jacqueline; Cernicharo, Jose

2004-01-01

ISO/LWS grating observations of the ultraluminous infrared galaxy Arp 220 shows absorption in molecular lines of OH, H 2 0 , CH, NH, and "3, well as in the [0 I] 63 pm line and emission in the [C 111 158 pm line. We have modeled the continuum and the emission/absorption of all observed features by means of a non-local radiative transfer code. The continuum from 25 to 1300 pm is modeled AS A WARM (106 K) NUCLEAR REGION THAT IS OPTICALLY THICK IN THE FAR-INFRARED, attenuated by an extended region (size 2") that is heated mainly through absorption of nuclear infrared radiation. The molecular absorption in the nuclear region is characterized by high excitation due to the high infrared radiation density. The OH column densities are high toward the nucleus and the extended region (about 2 x 10 sup 17 cm sup-2). The H2O column density is also high toward the nucleus (2 - 10 x 1017 cm-2) and lower in the extended region. The column densities in a halo that accounts for the absorption by the lowest lying levels are similar to what are found in the diffuse clouds toward the star forming regions in the Sgr B2 molecular cloud complex near the Galactic Center. Most notable are the high column densities found for NH and NH3 toward the nucleus, with values of about 1.5 x 10supl6 cmsup-2 and about 3 x 10supl6 cmsup-2, respectively, whereas the NH2 column density is lower than about 2 x 10sup15 cmsup-2. A combination of PDRs in the extended region and hot cores with enhanced H20 photodissociation and a possible shock contribution in the nuclei may explain the relative column densities of OH and H20, whereas the nitrogen chemistry may be strongly affected by cosmic ray ionization. The [C II] 158 pm line is well reproduced by our models and its "deficit" relative to the CII/FIR ratio in normal and starburst galaxies is suggested to be mainly a consequence of the dominant non-PDR component of far- infrared radiation, ALTHOUGH OUR MODELS ALONE CANNOT RULE OUT EXTINCTION EFFECTS IN THE NUCLEI.

The Far-Infrared Spectrum of Arp 220

NASA Technical Reports Server (NTRS)

Gonzalez-Alfonso, Eduardo; Smith, Howard A.; Fischer, Jacqueline; Cernicharo, Jose

2005-01-01

ISO/LWS grating observations of the ultraluminous infrared galaxy Arp 220 shows absorption in molecular lines of OH, H(sub 2)O, CH, NH, and NH(sub 3), as well as in the [O I] 63 micron line and emission in the [C II] 158 micron line. We have modeled the continuum and the emission/absorption of all observed features by means of a non-local radiative transfer code. The continuum from 25 to 1300 microns is modeled as a warm (106 K) nuclear region that is optically thick in the far-infrared, attenuated by an extended region (size 2") that is heated mainly through absorption of nuclear infrared radiation. The molecular absorption in the nuclear region is characterized by high excitation due to the high infrared radiation density. The OH column densities are high toward the nucleus (2 - 6 x 10(exp 17) cm(exp -2)) and the extended region (approximately 2 x 10(exp 17) cm(exp -2)). The H(sub 2)O column density is also high toward the nucleus (2 - 10 x 10(exp 17) cm(exp -2)) and lower in the extended region. The column densities in a halo that accounts for the absorption by the lowest lying levels are similar to what are found in the diffuse clouds toward the star forming regions in the Sgr B2 molecular cloud complex near the Galactic Center. Most notable are the high column densities found for NH and NH(sub 3) toward the nucleus, with values of approximately 1.5 x 10(exp 16) cm(exp -2) and approximately 3 x 10(exp 16) cm(exp -2), respectively, whereas the NH(sub 2) column density is lower than approximately 2 x 10(exp 15) cm(exp -2). A combination of PDRs in the extended region and hot cores with enhanced H(sub 2)O photodissociation and a possible shock contribution in the nuclei may explain the relative column densities of OH and H(sub 2)O, whereas the nitrogen chemistry may be strongly affected by cosmic ray ionization. The [C II] 158 micron line is well reproduced by our models and its deficit relative to the CII/FIR ratio in normal and starburst galaxies is suggested to be mainly a consequence of the dominant non-PDR component of far-infrared radiation, although our models alone cannot rule out extinction effects in the nuclei.

Short-column anion-exchange chromatography for soil and peat humic substances profiling by step-wise gradient of high pH aqueous sodium ethylenediaminetetraacetate.

PubMed

Hutta, Milan; Ráczová, Janka; Góra, Róbert; Pessl, Juraj

2015-08-21

Novel anion-exchange liquid chromatographic method with step gradient of aqueous EDTA(4-) based mobile phase elution has been developed to profile available Slovak soil humic substances and alkaline extracts of various soils. The method utilize short glass column (30mm×3mm) filled in with hydrolytically stable particles (60μm diameter) Separon HEMA-BIO 1000 having (diethylamino)ethyl functional groups. Step gradient was programmed by mixing mobile phase composed of aqueous solution of sodium EDTA (pH 12.0; 5mmolL(-1)) and mobile phase constituted of aqueous solution of sodium EDTA (pH 12.0, 500mmolL(-1)). The FLD of HSs was set to excitation wavelength 480nm and emission wavelength 530nm (λem). Separation mechanism was studied by use of selected aromatic acids related to humic acids with the aid of UV spectrophotometric detection at 280nm. The proposed method benefits from high ionic strength (I=5molL(-1)) of the end mobile phase buffer and provides high recovery of humic acids (98%). Accurate and reproducible profiling of studied humic substances, alkaline extracts of various types of soils enables straightforward characterization and differentiation of HSs in arable and forest soils. Selected model aromatic acids were used for separation mechanism elucidation. Copyright © 2015 Elsevier B.V. All rights reserved.

Metal concentrations in the upper atmosphere during meteor showers

NASA Astrophysics Data System (ADS)

Correira, J.; Aikin, A. C.; Grebowsky, J. M.; Burrows, J. P.

2010-02-01

Using the nadir-viewing Global Ozone Measuring Experiment (GOME) UV/VIS spectrometer on the ERS-2 satellite, we investigate short term variations in the vertical magnesium column densities in the atmosphere and any connection to possible enhanced mass deposition during a meteor shower. Time-dependent mass influx rates are derived for all the major meteor showers using published estimates of mass density and temporal profiles of meteor showers. An average daily sporadic background mass flux rate is also calculated and used as a baseline against which calculated shower mass flux rates are compared. These theoretical mass flux rates are then compared with GOME derived metal vertical column densities of Mg and Mg+ from the years 1996-2001. There is no correlation between theoretical mass flux rates and changes in the Mg and Mg+ metal column densities. A possible explanation for the lack of a shower related increase in metal concentrations may be differences in the mass regimes dominating the average background mass flux and shower mass flux.

Metal concentrations in the upper atmosphere during meteor showers

NASA Astrophysics Data System (ADS)

Correira, J.; Aikin, A. C.; Grebowsky, J. M.; Burrows, J. P.

2009-09-01

Using the nadir-viewing Global Ozone Measuring Experiment (GOME) UV/VIS spectrometer on the ERS-2 satellite, we investigate short term variations in the vertical magnesium column densities in the atmosphere and any connection to possible enhanced mass deposition during a meteor shower. Time-dependent mass influx rates are derived for all the major meteor showers using published estimates of mass density and temporal profiles of meteor showers. An average daily sporadic background mass flux rate is also calculated and used as a baseline against which calculated shower mass flux rates are compared. These theoretical mass flux rates are then compared with GOME derived metal vertical column densities of Mg and Mg+ from the years 1996-2001. There is no correlation between theoretical mass flux rates and changes in the Mg and Mg+ metal column densities. A possible explanation for the lack of a shower related increase in metal concentrations may be differences in the mass regimes dominating the average background mass flux and shower mass flux.

Stability of Sodium Nitroprusside in 5% Dextrose Stored at 4°C in Polypropylene Syringes Protected from Light.

PubMed

Anderson, Collin R; Collins, Deborah; Laursen, Trevor; Arave, Trevor; Helm, Michael

2016-01-01

Sodium nitroprusside is a potent vasodilator employed intraoperatively and within critical care areas. The photolabile pharmaceutical agent has been used for decades and various stability studies have been executed. Due to potential shortages and the desire to batch compound sodium nitroprusside at a concentration of 1 mg/mL in polypropylene syringes, a new stability study was performed. Chromatographic analysis was conducted on a C18 column, with elution via an aqueous phase of 0.01 M sodium phosphate monobasic, adjusted to pH 6.5 with sodium hydroxide, and methanol (97.5:2.5) at a rate of 1 mL/min, and subsequent ultraviolet detection at 210 nm. Triplicate determinations of four samples, stored under refrigeration at 4°C, were obtained initially and on days 2, 5, and 9. Turbidity and pH measurements were performed in conjunction with visual observation on days of chromatographic analysis. Results demonstrate that sodium nitroprusside compounded in 5% dextrose at a concentration of 1 mg/mL, stored at 4°C protected from light in polypropylene syringes, is physically and chemically stable for at least 9 days. Copyright© by International Journal of Pharmaceutical Compounding, Inc.

Tire-derived carbon composite anodes for sodium-ion batteries

DOE PAGES

Li, Yunchao; Paranthaman, M. Parans; Akato, Kokouvi; ...

2016-04-04

We report that hard-carbon materials are considered as one of the most promising anodes for the emerging sodium-ion batteries. Here, we report a low-cost, scalable waste tire-derived carbon as an anode for sodium-ion batteries (SIBs). The tire-derived carbons obtained by pyrolyzing the acid-treated tire at 1100 °C, 1400 °C and 1600 °C show capacities of 179, 185 and 203 mAh g -1, respectively, after 100 cycles at a current density of 20 mA g -1 in sodium-ion batteries with good electrochemical stability. The portion of the low-voltage plateau region in the charge-discharge curves increases as the heat-treatment temperature increases. Themore » low-voltage plateau is beneficial to enhance the energy density of the full cell. However, this plateau suffers rapid capacity fade at higher current densities. This study provides a new pathway for inexpensive, environmentally benign and value-added waste tire-derived products towards large-scale energy storage applications.« less

Interactions between beta-2 adrenoceptor gene variation, cardiovascular control and dietary sodium in healthy young adults

PubMed Central

Eisenach, John H; Schroeder, Darrell R; Pavey, Emily S; Penheiter, Alan R; Knutson, Jean N; Turner, Stephen T; Joyner, Michael J

2014-01-01

Dietary sodium affects function of the beta-2 adrenoceptor (ADRB2). We tested the hypothesis that haplotype variation in the ADRB2 gene would influence the cardiovascular and regional vasodilator responses to sympathoexcitatory manoeuvres following low, normal and high sodium diets, and ADRB2-mediated forearm vasodilation in the high sodium condition. Seventy-one healthy young adults were grouped by double homozygous haplotypes: Arg16+Gln27 (n = 31), the rare Gly16+Gln27 (n = 10) and Gly16+Glu27 (n = 30). Using a randomized cross-over design, subjects were studied following 5 days of controlled low, normal and high sodium with 1 month or longer between diets (and low hormone phase of the menstrual cycle). All three visits utilized ECG and finger plethysmography for haemodynamic measures, and the high sodium visit included a brachial arterial catheter for forearm vasodilator responses to isoprenaline with plethysmography. Lymphocytes were sampled for ex vivo analysis of ADRB2 density and binding conformation. We found a main effect of haplotype on ADRB2 density (P = 0.03) with the Gly16+Glu27 haplotype having the greatest density (low, normal, high sodium: 12.9 ± 0.9, 13.5 ± 0.9 and 13.6 ± 0.8 fmol mg−1 protein, respectively) and Arg16+Gln27 having the least (9.3 ± 0.6, 10.1 ± 0.5 and 10.3 ± 0.6  fmol mg−1 protein, respectively), but there were no sodium or haplotype effects on receptor binding conformation. In the mental stress trial, there was a main effect of haplotype on cardiac output (P = 0.04), as Arg16+Gln27 had the lowest responses. Handgrip and forearm vasodilation yielded no haplotype differences, and no correlations were present for ADRB2 density and haemodynamics. Our findings support cell-based evidence that ADRB2 haplotype influences ADRB2 protein expression independent of dietary sodium, yet the haemodynamic consequences appear modest in healthy humans. PMID:25260632

Ratios of molecular hydrogen line intensities in shocked gas - Evidence for cooling zones

NASA Technical Reports Server (NTRS)

Brand, P. W. J. L.; Moorhouse, A.; Bird, M.; Burton, M. G.; Geballe, T. R.

1988-01-01

Column densities of molecular hydrogen have been calculated from 19 infrared vibration-rotation and pure rotational line intensities measured at peak 1 of the Orion molecular outflow. The run of column density with energy level is similar to a simple coolng zone model of the line-emitting region, but is not well fitted by predictions of C-shock models current in the literature.

Non-detection of HC11N towards TMC-1: constraining the chemistry of large carbon-chain molecules

NASA Astrophysics Data System (ADS)

Loomis, Ryan A.; Shingledecker, Christopher N.; Langston, Glen; McGuire, Brett A.; Dollhopf, Niklaus M.; Burkhardt, Andrew M.; Corby, Joanna; Booth, Shawn T.; Carroll, P. Brandon; Turner, Barry; Remijan, Anthony J.

2016-12-01

Bell et al. reported the first detection of the cyanopolyyne HC11N towards the cold dark cloud TMC-1; no subsequent detections have been reported towards any source. Additional observations of cyanopolyynes and other carbon-chain molecules towards TMC-1 have shown a log-linear trend between molecule size and column density, and in an effort to further explore the underlying chemical processes driving this trend, we have analysed Green Bank Telescope observations of HC9N and HC11N towards TMC-1. Although we find an HC9N column density consistent with previous values, HC11N is not detected and we derive an upper limit column density significantly below that reported in Bell et al. Using a state-of-the-art chemical model, we have investigated possible explanations of non-linearity in the column density trend. Despite updating the chemical model to better account for ion-dipole interactions, we are not able to explain the non-detection of HC11N, and we interpret this as evidence of previously unknown carbon-chain chemistry. We propose that cyclization reactions may be responsible for the depleted HC11N abundance, and that products of these cyclization reactions should be investigated as candidate interstellar molecules.

Cathode-constriction and column-constriction in high current vacuum arcs subjected to an axial magnetic field

NASA Astrophysics Data System (ADS)

Zhang, Zaiqin; Ma, Hui; Liu, Zhiyuan; Geng, Yingsan; Wang, Jianhua

2018-04-01

The influence of the applied axial magnetic field on the current density distribution in the arc column and electrodes is intensively studied. However, the previous results only provide a qualitative explanation, which cannot quantitatively explain a recent experimental data on anode current density. The objective of this paper is to quantitatively determine the current constriction subjected to an axial magnetic field in high-current vacuum arcs according to the recent experimental data. A magnetohydrodynamic model is adopted to describe the high current vacuum arcs. The vacuum arc is in a diffuse arc mode with an arc current ranged from 6 kArms to 14 kArms and an axial magnetic field ranged from 20 mT to 110 mT. By a comparison of the recent experimental work of current density distribution on the anode, the modelling results show that there are two types of current constriction. On one hand, the current on the cathode shows a constriction, and this constriction is termed as the cathode-constriction. On the other hand, the current constricts in the arc column region, and this constriction is termed as the column-constriction. The cathode boundary is of vital importance in a quantitative model. An improved cathode constriction boundary is proposed. Under the improved boundary, the simulation results are in good agreement with the recent experimental data on the anode current density distribution. It is demonstrated that the current density distribution at the anode is sensitive to that at the cathode, so that measurements of the anode current density can be used, in combination with the vacuum arc model, to infer the cathode current density distribution.

The VLT-FLAMES Tarantula Survey. IX. The interstellar medium seen through diffuse interstellar bands and neutral sodium&

NASA Astrophysics Data System (ADS)

van Loon, J. Th.; Bailey, M.; Tatton, B. L.; Maíz Apellániz, J.; Crowther, P. A.; de Koter, A.; Evans, C. J.; Hénault-Brunet, V.; Howarth, I. D.; Richter, P.; Sana, H.; Simón-Díaz, S.; Taylor, W.; Walborn, N. R.

2013-02-01

Context. The Tarantula Nebula (a.k.a. 30 Dor) is a spectacular star-forming region in the Large Magellanic Cloud (LMC), seen through gas in the Galactic disc and halo. Diffuse interstellar bands (DIBs) offer a unique probe of the diffuse, cool-warm gas in these regions. Aims: The aim is to use DIBs as diagnostics of the local interstellar conditions, whilst at the same time deriving properties of the yet-unknown carriers of these enigmatic spectral features. Methods: Spectra of over 800 early-type stars from the Very Large Telescope Flames Tarantula Survey (VFTS) were analysed. Maps were created, separately, for the Galactic and LMC absorption in the DIBs at 4428 and 6614 Å and - in a smaller region near the central cluster R 136 - neutral sodium (the Na i D doublet); we also measured the DIBs at 5780 and 5797 Å. Results: The maps show strong 4428 and 6614 Å DIBs in the quiescent cloud complex to the south of 30 Dor but weak absorption in the harsher environments to the north (bubbles) and near the OB associations. The Na maps show at least five kinematic components in the LMC and a shell-like structure surrounding R 136, and small-scale structure in the Milky Way. The strengths of the 4428, 5780, 5797 and 6614 Å DIBs are correlated, also with Na absorption and visual extinction. The strong 4428 Å DIB is present already at low Na column density but the 6614, 5780 and 5797 Å DIBs start to be detectable at subsequently larger Na column densities. Conclusions: The carriers of the 4428, 6614, 5780 and 5797 Å DIBs are increasingly prone to removal from irradiated gas. The relative strength of the 5780 and 5797 Å DIBs clearly confirm the Tarantula Nebula as well as Galactic high-latitude gas to represent a harsh radiation environment. The resilience of the 4428 Å DIB suggests its carrier is large, compact and neutral. Structure is detected in the distribution of cool-warm gas on scales between one and >100 pc in the LMC and as little as 0.01 pc in the Sun's vicinity. Stellar winds from the central cluster R 136 have created an expanding shell; some infalling gas is also detected, reminiscent of a galactic "fountain". Full Tables A.2-A.4 are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/550/A108

A study of chemical remediation on 1,2,4-Trichlorobenzene in groundwater

NASA Astrophysics Data System (ADS)

Ye, S.

2015-12-01

Shujun Ye, Guanqun Wang, and Jichun WuKey Laboratory of Surficial Geochemistry, Ministry of Education; School of Earth Sciences and Engineering, Nanjing University, Nanjing 210093, China, Nanjing, 210093, China; sjye@nju.edu.cn The ground water is contaminated by 1,2,4 Trichlorobenzene (TCB) in a former chemical plant in Nanjing, China. So 1,2,4-TCB is the contaminant of concern in this study. As chemical oxidation technology is a common in-site remediation technique, hydrogen peroxide, sodium sulfate and the two-mixed oxidants under the catalytic condition are used to remove 1,2,4-TCB from groundwater. By changing the values of temperature and pH in the experiments, the best conditions for chemical oxidation with oxidants mentioned above were determined. The fluorescent brightener of PF, manufactured by the former chemical plant, was added to groundwater to evaluate whether its existence made an impact on the chemical oxidation. 1-D sand column tests were conducted to study the degradation effect by using the chemical oxidation technology. The experiment results showed that single oxidant and mixed both oxidants can remove 1,2,4-TCB completely. The oxidation efficiency of both oxidants is influenced by temperature and pH. For hydrogen peroxide, the oxidation efficiency decreases with the increase of pH, while, for sodium sulfate, the efficiency is high under the mild acidic condition. The fluorescent brightener PF has an impact on the oxidation efficiency, with negative effect on the oxidation with hydrogen peroxide but positive effect with sodium sulfate. 1-D sand column tests testified the degradation of 1,2,4-TCB by the chemical oxidation with hydrogen peroxide and sodium sulfate. KEY WORDS: 1,2,4-trichlorobenzene hydrogen peroxide sodium persulfate optical brightener PF chemical oxidation AcknowledgementsFunding for this research from DuPont Company and NSFC Project No. 41472212.

Hupresin Retains Binding Capacity for Butyrylcholinesterase and Acetylcholinesterase after Sanitation with Sodium Hydroxide.

PubMed

Onder, Seda; David, Emilie; Tacal, Ozden; Schopfer, Lawrence M; Lockridge, Oksana

2017-01-01

Hupresin is a new affinity resin that binds butyrylcholinesterase (BChE) in human plasma and acetylcholinesterase (AChE) solubilized from red blood cells (RBC). Hupresin is available from the CHEMFORASE company. BChE in human plasma binds to Hupresin and is released with 0.1 M trimethylammonium bromide (TMA) with full activity and 10-15% purity. BChE immunopurified from plasma by binding to immobilized monoclonal beads has fewer contaminating proteins than the one-step Hupresin-purified BChE. However, when affinity chromatography on Hupresin follows ion exchange chromatography at pH 4.5, BChE is 99% pure. The membrane bound AChE, solubilized from human RBC with 0.6% Triton X-100, binds to Hupresin and remains bound during washing with sodium chloride. Human AChE is not released in significant quantities with non-denaturing solvents, but is recovered in 1% trifluoroacetic acid. The denatured, partially purified AChE is useful for detecting exposure to nerve agents by mass spectrometry. Our goal was to determine whether Hupresin retains binding capacity for BChE and AChE after Hupresin is washed with 0.1 M NaOH. A 2 mL column of Hupresin equilibrated in 20 mM TrisCl pH 7.5 was used in seven consecutive trials to measure binding and recovery of BChE from 100 mL human plasma. Between each trial the Hupresin was washed with 10 column volumes of 0.1 M sodium hydroxide. A similar trial was conducted with red blood cell AChE in 0.6% Triton X-100. It was found that the binding capacity for BChE and AChE was unaffected by washing Hupresin with 0.1 M sodium hydroxide. Hupresin could be washed with sodium hydroxide at least seven times without losing binding capacity.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wu, Qin; Zaikowski, Lori; Kaur, Parmeet

Conjugated oligofluorenes are chemically reduced up to five charges in tetrahydrofuran solvent and confirmed with clear spectroscopic evidence. Stimulated by these experimental results, we have conducted a comprehensive computational study of the electronic structure and the solvation structure of representative oligofluorene anions with a focus on the pairing between sodium ions and these multianions. In addition, using density functional theory (DFT) methods and a solvation model of both explicit solvent molecules and implicit polarizable continuum, we first elucidate the structure of tightly solvated free sodium ions, and then explore the pairing of sodium ions either in contact with reduced oligofluorenesmore » or as solvent-separated ion pairs. Computed time-dependent-DFT absorption spectra are compared with experiments to assign the dominant ion pairing structure for each multianion. Computed ion pair binding energies further support our assignment. Lastly, the availability of different length and reducing level of oligofluorenes enables us to investigate the effects of total charge and charge density on the binding with sodium ions, and our results suggest both factors play important roles in ion pairing for small molecules. However, as the oligofluorene size grows, its charge density determines the binding strength with the sodium ion.« less

Low density of neutral hydrogen and helium in the local interstellar medium: Extreme Ultraviolet Explorer photometry of the Lyman continuum of the hot white dwarfs MCT 0501-2858, MCT 0455-2812, HZ 43, and GD 153

NASA Technical Reports Server (NTRS)

Vennes, Stephane; Dupuis, Jean; Bowyer, Stuart; Fontaine, Gilles; Wiercigroch, Alexandria; Jelinsky, Patrick; Wesemael, Francois; Malina, Roger

1994-01-01

The first comprehensive sky survey of the extreme ultraviolet (EUV) spectral range performed by the Extreme Ultraviolet Explorer (EUVE) has uncovered a handful of very bright sources at wavelengths longer than the He I 504 A photoionization edge. Among these objects are four white dwarfs with exceptionally low interstellar medium (ISM) column densities along the line of sight. Analysis of EUV photometry of the He-rich DO white dwarf MCT 0501-2858 and the H-rich DA white dwarf MCT 0455-2812 along one line of sight and of the DA white dwarfs HZ 43 and GD 153 near the north Galactic pole indicates that the overall minimum column density of the neutral material centered on the Sun is N(H I) = 0.5-1.0 x 10(exp 18)/sq cm. In the case of MCT 0501-2858, EUV photometric measurements provide a clear constraint to the effective temperature (60,000-70,000 K). Given these neutral hydrogen columns, the actual contribution to the density of neutral species from the immediate solar environment (the 'local fluff') would only cover a distance of approximately equals 2-3 pc (assuming an average density n(H I) = 0.1/cu cm) leaving these lines of sight almost entirely within the hot phase of the ISM. A preliminary examination of the complete EUVE long-wavelength survey indicates that these lines of sight are exceptional and set a minimum column density in the solar environment.

The puzzling spectrum of HD 94509. Sounding out the extremes of Be shell star spectral morphology

NASA Astrophysics Data System (ADS)

Cowley, C. R.; Przybilla, N.; Hubrig, S.

2015-06-01

Context. The spectral features of HD 94509 are highly unusual, adding an extreme to the zoo of Be and shell stars. The shell dominates the spectrum, showing lines typical for spectral types mid-A to early-F, while the presence of a late/mid B-type central star is indicated by photospheric hydrogen line wings and helium lines. Numerous metallic absorption lines have broad wings but taper to narrow cores. They cannot be fit by Voigt profiles. Aims: We describe and illustrate unusual spectral features of this star, and make rough calculations to estimate physical conditions and abundances in the shell. Furthermore, the central star is characterized. Methods: We assume mean conditions for the shell. An electron density estimate is made from the Inglis-Teller formula. Excitation temperatures and column densities for Fe i and Fe ii are derived from curves of growth. The neutral H column density is estimated from high Paschen members. The column densities are compared with calculations made with the photoionization code Cloudy. Atmospheric parameters of the central star are constrained employing non-LTE spectrum synthesis. Results: Overall chemical abundances are close to solar. Column densities of the dominant ions of several elements, as well as excitation temperatures and the mean electron density are well accounted for by a simple model. Several features, including the degree of ionization, are less well described. Conclusions: HD 94509 is a Be star with a stable shell, close to the terminal-age main sequence. The dynamical state of the shell and the unusually shaped, but symmetric line profiles, require a separate study.

A safe, effective, and facility compatible cleaning in place procedure for affinity resin in large-scale monoclonal antibody purification.

PubMed

Wang, Lu; Dembecki, Jill; Jaffe, Neil E; O'Mara, Brian W; Cai, Hui; Sparks, Colleen N; Zhang, Jian; Laino, Sarah G; Russell, Reb J; Wang, Michelle

2013-09-20

Cleaning-in-place (CIP) for column chromatography plays an important role in therapeutic protein production. A robust and efficient CIP procedure ensures product quality, improves column life time and reduces the cost of the purification processes, particularly for those using expensive affinity resins, such as MabSelect protein A resin. Cleaning efficiency, resin compatibility, and facility compatibility are the three major aspects to consider in CIP process design. Cleaning MabSelect resin with 50mM sodium hydroxide (NaOH) along with 1M sodium chloride is one of the most popular cleaning procedures used in biopharmaceutical industries. However, high concentration sodium chloride is a leading cause of corrosion in the stainless steel containers used in large scale manufacture. Corroded containers may potentially introduce metal contaminants into purified drug products. Therefore, it is challenging to apply this cleaning procedure into commercial manufacturing due to facility compatibility and drug safety concerns. This paper reports a safe, effective and environmental and facility-friendly cleaning procedure that is suitable for large scale affinity chromatography. An alternative salt (sodium sulfate) is used to prevent the stainless steel corrosion caused by sodium chloride. Sodium hydroxide and salt concentrations were optimized using a high throughput screening approach to achieve the best combination of facility compatibility, cleaning efficiency and resin stability. Additionally, benzyl alcohol is applied to achieve more effective microbial control. Based on the findings, the recommended optimum cleaning strategy is cleaning MabSelect resin with 25 mM NaOH, 0.25 M Na2SO4 and 1% benzyl alcohol solution every cycle, followed by a more stringent cleaning using 50 mM NaOH with 0.25 M Na2SO4 and 1% benzyl alcohol at the end of each manufacturing campaign. A resin life cycle study using the MabSelect affinity resin demonstrates that the new cleaning strategy prolongs resin life time and consistently delivers high purity drug products. Copyright © 2013 Elsevier B.V. All rights reserved.

Mini-columns for Conducting Breakthrough Experiments. Design and Construction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dittrich, Timothy M.; Reimus, Paul William; Ware, Stuart Douglas

Experiments with moderately and strongly sorbing radionuclides (i.e., U, Cs, Am) have shown that sorption between experimental solutions and traditional column materials must be accounted for to accurately determine stationary phase or porous media sorption properties (i.e., sorption site density, sorption site reaction rate coefficients, and partition coefficients or K d values). This report details the materials and construction of mini-columns for use in breakthrough columns to allow for accurate measurement and modeling of sorption parameters. Material selection, construction techniques, wet packing of columns, tubing connections, and lessons learned are addressed.

Retardation of mobile radionuclides in granitic rock fractures by matrix diffusion

NASA Astrophysics Data System (ADS)

Hölttä, P.; Poteri, A.; Siitari-Kauppi, M.; Huittinen, N.

Transport of iodide and sodium has been studied by means of block fracture and core column experiments to evaluate the simplified radionuclide transport concept. The objectives were to examine the processes causing retention in solute transport, especially matrix diffusion, and to estimate their importance during transport in different scales and flow conditions. Block experiments were performed using a Kuru Grey granite block having a horizontally planar natural fracture. Core columns were constructed from cores drilled orthogonal to the fracture of the granite block. Several tracer tests were performed using uranine, 131I and 22Na as tracers at water flow rates 0.7-50 μL min -1. Transport of tracers was modelled by applying the advection-dispersion model based on the generalized Taylor dispersion added with matrix diffusion. Scoping calculations were combined with experiments to test the model concepts. Two different experimental configurations could be modelled applying consistent transport processes and parameters. The processes, advection-dispersion and matrix diffusion, were conceptualized with sufficient accuracy to replicate the experimental results. The effects of matrix diffusion were demonstrated on the slightly sorbing sodium and mobile iodine breakthrough curves.

A logNHI = 22.6 Damped Lyα Absorber in a Dark Gamma-Ray Burst: The Environment of GRB 050401

NASA Astrophysics Data System (ADS)

Watson, D.; Fynbo, J. P. U.; Ledoux, C.; Vreeswijk, P.; Hjorth, J.; Smette, A.; Andersen, A. C.; Aoki, K.; Augusteijn, T.; Beardmore, A. P.; Bersier, D.; Castro Cerón, J. M.; D'Avanzo, P.; Diaz-Fraile, D.; Gorosabel, J.; Hirst, P.; Jakobsson, P.; Jensen, B. L.; Kawai, N.; Kosugi, G.; Laursen, P.; Levan, A.; Masegosa, J.; Näränen, J.; Page, K. L.; Pedersen, K.; Pozanenko, A.; Reeves, J. N.; Rumyantsev, V.; Shahbaz, T.; Sharapov, D.; Sollerman, J.; Starling, R. L. C.; Tanvir, N.; Torstensson, K.; Wiersema, K.

2006-12-01

The optical afterglow spectrum of GRB 050401 (at z=2.8992+/-0.0004) shows the presence of a damped Lyα absorber (DLA), with logNHI=22.6+/-0.3. This is the highest column density ever observed in a DLA and is about 5 times larger than the strongest DLA detected so far in any QSO spectrum. From the optical spectrum, we also find a very large Zn column density, implying an abundance of [Zn/H]=-1.0+/-0.4. These large columns are supported by the early X-ray spectrum from Swift XRT, which shows a column density (in excess of Galactic) of logNH=22.21+0.06-0.08 assuming solar abundances (at z=2.9). The comparison of this X-ray column density, which is dominated by absorption due to α-chain elements, and the H I column density derived from the Lyα absorption line allows us to derive a metallicity for the absorbing matter of [α/H]=-0.4+/-0.3. The optical spectrum is reddened and can be well reproduced with a power law with SMC extinction, where AV=0.62+/-0.06. But the total optical extinction can also be constrained independent of the shape of the extinction curve: from the optical to X-ray spectral energy distribution, we find 0.5<~AV<~4.5. However, even this upper limit, independent of the shape of the extinction curve, is still well below the dust column that is inferred from the X-ray column density, i.e., AV=9.1+1.4-1.5. This discrepancy might be explained by a small dust content with high metallicity (low dust-to-metals ratio). ``Gray'' extinction cannot explain the discrepancy, since we are comparing the metallicity to a measurement of the total extinction (without reference to the reddening). Little dust with high metallicity may be produced by sublimation of dust grains or may naturally exist in systems younger than a few hundred megayears. Based in part on observations made at the European Southern Observatory, Paranal, Chile under program 075.D-0270, with the Nordic Optical Telescope, operated on the island of La Palma jointly by Denmark, Finland, Iceland, Norway, and Sweden, in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias, with the Wide Field Camera (WFCAM) on the United Kingdom Infrared Telescope, which is operated by the Joint Astronomy Centre on behalf of the UK Particle Physics and Astronomy Research Council, and on data collected at the Subaru Telescope, which is operated by the National Astronomical Observatory of Japan.

Measurement of trace nitrate concentrations in seawater by ion chromatography with valve switching

NASA Astrophysics Data System (ADS)

Du, Juan; Fa, Yun; Zheng, Yue; Li, Xuebing; Du, Fanglin; Yang, Haiyan

2014-05-01

An ion chromatographic method with a valve switching facility was developed to determine trace nitrate concentrations in seawater using two pumps, two different suppressors, and two columns. A carbohydrate membrane desalter was used to reduce the high concentrations of sodium salts in samples. In this method, trace nitrate was eluted from the concentrator column to the analytical columns, while the matrix fl owed to waste. Neither chemical pre-treatment nor sample dilution was required. In the optimized separation conditions, the method showed good linearity ( R >0.99) in the 0.05 and 50 mg/L concentration range, and satisfactory repeatability (RSD<5%, n =6). The limit of detection for nitrate was 0.02 mg/L. Results showed that the valve switching system was suitable and practical for the determination of trace nitrate in seawater.

Association of urinary sodium/creatinine ratio with bone mineral density in postmenopausal women: KNHANES 2008-2011.

PubMed

Kim, Sung-Woo; Jeon, Jae-Han; Choi, Yeon-Kyung; Lee, Won-Kee; Hwang, In-Ryang; Kim, Jung-Guk; Lee, In-Kyu; Park, Keun-Gyu

2015-08-01

Accumulating evidence shows that high sodium chloride intake increases urinary calcium excretion and may be a risk factor for osteoporosis. However, the effect of oral sodium chloride intake on bone mineral density (BMD) and risk of osteoporosis has been inadequately researched. The aim of the present study was to determine whether urinary sodium excretion (reflecting oral sodium chloride intake) associates with BMD and prevalence of osteoporosis in postmenopausal women. This cross-sectional study involved a nationally representative sample consisting of 2,779 postmenopausal women who participated in the Korea National Health and Nutritional Examination Surveys in 2008-2011. The association of urinary sodium/creatinine ratio with BMD and other osteoporosis risk factors was assessed. In addition, the prevalence of osteoporosis was assessed in four groups with different urinary sodium/creatinine ratios. Participants with osteoporosis had significantly higher urinary sodium/creatinine ratios than the participants without osteoporosis. After adjusting for multiple confounding factors, urinary sodium/creatinine ratio correlated inversely with lumbar spine BMD (P = 0.001). Similarly, when participants were divided into quartile groups according to urinary sodium/creatinine ratio, the average BMD dropped as the urinary sodium/creatinine ratio increased. Multiple logistic regression analysis revealed that compared to quartile 1, quartile 4 had a significantly increased prevalence of lumbar spine osteoporosis (odds ratios 1.346, P for trend = 0.044). High urinary sodium excretion was significantly associated with low BMD and high prevalence of osteoporosis in lumbar spine. These results suggest that high sodium chloride intake decreases lumbar spine BMD and increases the risk of osteoporosis in postmenopausal women.

Improved Reversibility of Fe3+ /Fe4+ Redox Couple in Sodium Super Ion Conductor Type Na3 Fe2 (PO4 )3 for Sodium-Ion Batteries.

PubMed

Rajagopalan, Ranjusha; Chen, Bo; Zhang, Zhicheng; Wu, Xing-Long; Du, Yonghua; Huang, Ying; Li, Bing; Zong, Yun; Wang, Jie; Nam, Gwang-Hyeon; Sindoro, Melinda; Dou, Shi Xue; Liu, Hua Kun; Zhang, Hua

2017-03-01

The methodology employed here utilizes the sodium super ion conductor type sodium iron phosphate wrapped with conducting carbon network to generate a stable Fe 3+ /Fe 4+ redox   couple, thereby exhibiting higher operating voltage and energy density of sodium-ion batteries. This new class of sodium iron phosphate wrapped by carbon also displays a cycling stability with >96% capacity retention after 200 cycles. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Effectiveness of sodium azide alone compared to sodium azide in combination with methyl nitrosurea for rice mutagenesis

USDA-ARS?s Scientific Manuscript database

Rice seeds of the temperate japonica cultivar Kitaake were mutagenized with sodium azide alone and in combination with methyl nitrosourea. Using the reduced representation sequencing method Restriction Enzyme Sequence Comparative Analysis (RESCAN), the mutation densities, types and local sequence co...

Column densities resulting from shuttle sublimator/evaporator operation. [optical density of nozzle flow containing water vapor

NASA Technical Reports Server (NTRS)

Naumann, R. J.

1973-01-01

The proposed disposal of H2O from the shuttle fuel cell operation by ejecting it in vapor form through a supersonic nozzle at the rate of 100 lb/day has been investigated from the point of view of the possible interference to astronomical experiments. If the nozzle is located at the tail and directed along the shuttle longitudinal axis, the resulting column density will be less than 10 to th 12th power molecules/sq cm at viewing angles larger than 48 deg above the longitudinal axis. The molecules in the trail will diffuse rapidly. The column density contribution from molecules expelled on the previous orbit is 1.3 x 10 to the 8th power molecules/sq cm. This contribution diminishes by the inverse square root of the number of orbits since the molecules were expelled. The molecular backscatter from atmospheric molecules is also calculated. If the plume is directed into the flight path, the column density along a perpendicular is found to be 1.5 x 10 to the 11th power molecules/sq cm. The return flux is estimated to be of the order of 10 to the 12th power molecules/sq cm/sec at the stagnation point. With reasonable care in design of experiments to protect them from the backscatter flux of water molecules, the expulsion of 100 lb/day does not appear to create an insurmountable difficulty for the shuttle experiments.

Sodium benzoate and potassium sorbate preservatives in Iranian doogh.

PubMed

Zamani Mazdeh, F; Esmaeili Aftabdari, F; Moradi-Khatoonabadi, Z; Shaneshin, M; Torabi, P; Shams Ardekani, M R; Hajimahmoodi, M

2014-01-01

Sodium benzoate and potassium sorbate are two common preservatives used in Iran, yet use of these preservatives in doogh (Iranian dairy-based drink) is forbidden according to national standards. The aim of this study was to consider the presence of these preservatives in doogh by high-performance liquid chromatography with UV detection (HPLC-UV). The method was performed using a C18 column and detection at 225 nm. The mobile phase contained ammonium acetate buffer (pH = 4.2) and acetonitrile (80:20 v/v). The survey included 130 samples of doogh for identification and quantification of the named preservatives. All samples contained sodium benzoate, but potassium sorbate was detected in only 13% of them. The means of benzoate and sorbate were 21.3 ± 2.7 and 13.3 ± 39.6 mg kg(-1), respectively. The limits of detection were 2 and 40 ng g(-1) for benzoate and sorbate, respectively. Results indicate that sodium benzoate may occur in doogh naturally.

Trends in Dietary Sodium from Food Sources in Australian Children and Adolescents from 2007 to 2011/12.

PubMed

Grimes, Carley A; Szymlek-Gay, Ewa A; Nowson, Caryl A

2018-05-01

In western countries, most children eat more sodium than is recommended. In Australia in 2009, voluntary sodium reformulation targets were adopted for nine categories of processed foods, but the impact of this initiative on children's sodium intake has not been assessed. To compare sodium consumption of Australian children aged 2 to 16 years from 2007 to 2011/12. Cross-sectional analysis of data from the 2007 Children's Nutrition and Physical Activity Survey (n=4,487) and the 2011/12 National Nutrition and Physical Activity Survey (n=2,548). A nationally representative sample of 6,705 Australian children aged 2 to 16 years who provided plausible 24-hour dietary recall data according to Goldberg cutoffs for misreporting of energy intake. Mean intakes of energy, sodium, and sodium density (mg/1,000 kcal) were assessed via one 24-hour dietary recall; measurement error models with up to two 24-hour dietary recalls were used to estimate usual sodium intake and the proportion of children exceeding the age-specific upper level for sodium. Statistical analysis incorporated survey weights and accounted for the complex survey design. Two-sample t-tests and two-sample test of proportions were used to assess differences in continuous and categorical variables between survey years. Dietary sodium declined by 8% between 2007 and 2011/12 (-188±SE 31 mg/day; P<0.001), and this was in conjunction with a 5% reduction in energy intake (98±19 kcal/day; P<0.001). When stratified by age group, significant reductions in sodium intake remained across all four age groups (ie, 2-3 years, 4-8 years, 9-13 years, and 14-16 years); similarly, with the exception of 2- to 3-year-old children, reductions in energy intake were observed across all other age groups. Overall sodium density declined by 2% (-29 mg/1,000 kcal/day; P=0.01); however, in age subgroup analysis the decline in sodium density only remained among children aged 2 to 3 years. The upper level for sodium was exceeded by 94% or more children in 2007 and 78% or more in 2011/2012. Although results suggest a small reduction in reported sodium intake over 5 years, most children in 2011/12 had a sodium intake that exceeded the recommended upper level. Ongoing efforts to reduce sodium in the diets of Australian children are required. Copyright © 2018 Academy of Nutrition and Dietetics. Published by Elsevier Inc. All rights reserved.

Protein aggregation under high concentration/density state during chromatographic and ultrafiltration processes.

PubMed

Arakawa, Tsutomu; Ejima, Daisuke; Akuta, Teruo

2017-02-01

Local transient high protein concentration or high density condition can occur during processing of protein solutions. Typical examples are saturated binding of proteins during column chromatography and high protein concentration on the semi-permeable membrane during ultrafiltration. Both column chromatography and ultrafiltration are fundamental technologies, specially for production of pharmaceutical proteins. We summarize here our experiences related to such high concentration conditions. Copyright © 2016 Elsevier B.V. All rights reserved.

VOLATILE-RICH CIRCUMSTELLAR GAS IN THE UNUSUAL 49 CETI DEBRIS DISK

DOE Office of Scientific and Technical Information (OSTI.GOV)

Roberge, Aki; Grady, Carol A.; Welsh, Barry Y.

2014-11-20

We present Hubble Space Telescope Space Telescope Imaging Spectrograph far-UV spectra of the edge-on disk around 49 Ceti, one of the very few debris disks showing submillimeter CO emission. Many atomic absorption lines are present in the spectra, most of which arise from circumstellar gas lying along the line-of-sight to the central star. We determined the line-of-sight C I column density, estimated the total carbon column density, and set limits on the O I column density. Surprisingly, no line-of-sight CO absorption was seen. We discuss possible explanations for this non-detection, and present preliminary estimates of the carbon abundances in themore » line-of-sight gas. The C/Fe ratio is much greater than the solar value, suggesting that 49 Cet harbors a volatile-rich gas disk similar to that of β Pictoris.« less

Carbon X-ray absorption in the local ISM: fingerprints in X-ray Novae spectra

NASA Astrophysics Data System (ADS)

Gatuzz, Efraín; Ness, J.-U.; Gorczyca, T. W.; Hasoglu, M. F.; Kallman, Timothy R.; García, Javier A.

2018-06-01

We present a study of the C K-edge using high-resolution LETGS Chandra spectra of four novae during their super-soft-source (SSS) phase. We identified absorption lines due to C II Kα, C III Kα and C III Kβ resonances. We used these astronomical observations to perform a benchmarking of the atomic data, which involves wavelength shifts of the resonances and photoionization cross-sections. We used improved atomic data to estimate the C II and C III column densities. The absence of physical shifts for the absorption lines, the consistence of the column densities between multiple observations and the high temperature required for the SSS nova atmosphere modeling support our conclusion about an ISM origin of the respective absorption lines. Assuming a collisional ionization equilibrium plasma the maximum temperature derived from the ratio of C II/C III column densities of the absorbers correspond to Tmax < 3.05 × 104 K.

Analysis of interstellar fragmentation structure based on IRAS images

NASA Technical Reports Server (NTRS)

Scalo, John M.

1989-01-01

The goal of this project was to develop new tools for the analysis of the structure of densely sampled maps of interstellar star-forming regions. A particular emphasis was on the recognition and characterization of nested hierarchical structure and fractal irregularity, and their relation to the level of star formation activity. The panoramic IRAS images provided data with the required range in spatial scale, greater than a factor of 100, and in column density, greater than a factor of 50. In order to construct a densely sampled column density map of a cloud complex which is both self-gravitating and not (yet?) stirred up much by star formation, a column density image of the Taurus region has been constructed from IRAS data. The primary drawback to using the IRAS data for this purpose is that it contains no velocity information, and the possible importance of projection effects must be kept in mind.

Density Gradients in Chemistry Teaching

ERIC Educational Resources Information Center

Miller, P. J.

1972-01-01

Outlines experiments in which a density gradient might be used to advantage. A density gradient consists of a column of liquid, the composition and density of which varies along its length. The procedure can be used in analysis of solutions and mixtures and in density measures of solids. (Author/TS)

A high energy and power sodium-ion hybrid capacitor based on nitrogen-doped hollow carbon nanowires anode

NASA Astrophysics Data System (ADS)

Li, Dongdong; Ye, Chao; Chen, Xinzhi; Wang, Suqing; Wang, Haihui

2018-04-01

The sodium ion hybrid capacitor (SHC) has been attracting much attention. However, the SHC's power density is significantly confined to a low level due to the sluggish ion diffusion in the anode. Herein, we propose to use an electrode with a high double layer capacitance as the anode in the SHC instead of insertion anodes. To this aim, nitrogen doped hollow carbon nanowires (N-HCNWs) with a high specific surface area are prepared, and the high capacitive contribution during the sodium ion storage process is confirmed by a series of electrochemical measurements. A new SHC consisting of a N-HCNW anode and a commercial active carbon (AC) cathode is fabricated for the first time. Due to the hybrid charge storage mechanism combining ion insertion and capacitive process, the as-fabricated SHC strikes a balance between the energy density and power density, a energy density of 108 Wh kg-1 and a power density of 9 kW kg-1 can be achieved, which overwhelms the electrochemical performances of most reported AC-based SHCs.

Fabrication Of Metal Chloride Cathodes By Sintering

NASA Technical Reports Server (NTRS)

Bugga, Ratnakumar V.; Di Stefano, Salvador; Bankston, C. Perry

1992-01-01

Transition-metal chloride cathodes for use in high-temperature rechargeable sodium batteries prepared by sintering transition-metal powders mixed with sodium chloride. Need for difficult and dangerous chlorination process eliminated. Proportions of transition metal and sodium chloride in mixture adjusted to suit specific requirements. Cathodes integral to sodium/metal-chloride batteries, which have advantages over sodium/sulfur batteries including energy densities, increased safety, reduced material and thermal-management problems, and ease of operation and assembly. Being evaluated for supplying electrical power during peak demand and electric vehicles.

Effect of sulfur doping on thermoelectric properties of Sodium Tantalate - A first principles study

NASA Astrophysics Data System (ADS)

Chowdary, Bharadwaj; Jayaraman, Kaushik; Molli, Muralikrishna

2018-05-01

In this work, we report the thermoelectric (TE) transport properties of perovskite-like Sodium Tantalate and studied the effect of Sulfur doping on TE properties of Sodium Tantalate. The band structures are calculated in the purview of density functional theory using the mBJ exchange correlation potential. The transport properties are evaluated using the Boltzmann transport theory in the constant relaxation time approximation. Our results suggest that Sulfur doped Sodium Tantalate is better n-type thermoelectric compared to Sodium Tantalate.

Visualization and simulation of density driven convection in porous media using magnetic resonance imaging

NASA Astrophysics Data System (ADS)

Montague, James A.; Pinder, George F.; Gonyea, Jay V.; Hipko, Scott; Watts, Richard

2018-05-01

Magnetic resonance imaging is used to observe solute transport in a 40 cm long, 26 cm diameter sand column that contained a central core of low permeability silica surrounded by higher permeability well-sorted sand. Low concentrations (2.9 g/L) of Magnevist, a gadolinium based contrast agent, produce density driven convection within the column when it starts in an unstable state. The unstable state, for this experiment, exists when higher density contrast agent is present above the lower density water. We implement a numerical model in OpenFOAM to reproduce the observed fluid flow and transport from a density difference of 0.3%. The experimental results demonstrate the usefulness of magnetic resonance imaging in observing three-dimensional gravity-driven convective-dispersive transport behaviors in medium scale experiments.

Properties of Two-Variety Natural Luffa Sponge Columns as Potential Mattress Filling Materials

PubMed Central

Chen, Yuxia; Zhang, Kaiting; Yuan, Fangcheng; Zhang, Tingting; Weng, Beibei; Wu, Shanshan; Huang, Aiyue; Su, Na; Guo, Yong

2018-01-01

Luffa sponge (LS) is a resourceful material with fibro-vascular reticulated structure and extremely high porosity, which make it a potential candidate for manufacturing light mattress. In this study, two types of LS columns, namely high-density (HD) and low-density (LD) columns, were investigated as materials for filling the mattress. The results showed that the compressive strength of HD LS columns was significantly greater than that of LD LS columns. However, the densification strains of the two types of LS column were both in the range of 0.6 to 0.7. Besides, HD LS columns separately pressed to the smooth plateau region and the initial densification region exhibited a partial recovery of instant height when they were unloaded, and then both of them showed no more than 4.2% of height recovery after being allowed to rest at a constant temperature and humidity for 24 h. In contrast, when LD LS columns were compressed to the smooth plateau region, the height recovery was less than 1.62% compared to when they were pressed to the initial densification region, and that was more than 15.62%. Similar to other plant fibers used as mattress fillers, the two types of LS columns also showed good water absorption capacity—both of them could absorb water from as much as 2.07 to 3.45 times their own weight. At the same time, the two types of LS columns also showed good water desorption. The water desorption ratio of HD and LD LS columns separately reached 76.86 and 91.44%, respectively, after being let rest at a constant temperature and humidity for 13 h. PMID:29614744

Mitigation of Liquefaction in Sandy Soils Using Stone Columns

NASA Astrophysics Data System (ADS)

Selcuk, Levent; Kayabalı, Kamil

2010-05-01

Soil liquefaction is one of the leading causes of earthquake-induced damage to structures. Soil improvement methods provide effective solutions to reduce the risk of soil liquefaction. Thus, soil ground treatments are applied using various techniques. However, except for a few ground treatment methods, they generally require a high cost and a lot of time. Especially in order to prevent the risk of soil liquefaction, stone columns conctructed by vibro-systems (vibro-compaction, vibro-replacement) are one of the traditional geotechnical methods. The construction of stone columns not only enhances the ability of clean sand to drain excess pore water during an earthquake, but also increases the relative density of the soil. Thus, this application prevents the development of the excess pore water pressure in sand during earthquakes and keeps the pore pressure ratio below a certain value. This paper presents the stone column methods used against soil liquefaction in detail. At this stage, (a) the performances of the stone columns were investigated in different spacing and diameters of columns during past earthquakes, (b) recent studies about design and field applications of stone columns were presented, and (c) a new design method considering the relative density of soil and the capacity of drenage of columns were explained in sandy soil. Furthermore, with this new method, earthquake performances of the stone columns constructed at different areas were investigated before the 1989 Loma Prieta and the 1994 Northbridge earthquakes, as case histories of field applications, and design charts were compiled for suitable spacing and diameters of stone columns with consideration to the different sandy soil parameters and earhquake conditions. Key Words: Soil improvement, stone column, excess pore water pressure

Monte Carlo Model Insights into the Lunar Sodium Exosphere

NASA Technical Reports Server (NTRS)

Hurley, Dana M.; Killen, R. M.; Sarantos, M.

2012-01-01

Sodium in the lunar exosphere is released from the lunar regolith by several mechanisms. These mechanisms include photon stimulated desorption (PSD), impact vaporization, electron stimulated desorption, and ion sputtering. Usually, PSD dominates; however, transient events can temporarily enhance other release mechanisms so that they are dominant. Examples of transient events include meteor showers and coronal mass ejections. The interaction between sodium and the regolith is important in determining the density and spatial distribution of sodium in the lunar exosphere. The temperature at which sodium sticks to the surface is one factor. In addition, the amount of thermal accommodation during the encounter between the sodium atom and the surface affects the exospheric distribution. Finally, the fraction of particles that are stuck when the surface is cold that are rereleased when the surface warms up also affects the exospheric density. In [1], we showed the "ambient" sodium exosphere from Monte Carlo modeling with a fixed source rate and fixed surface interaction parameters. We compared the enhancement when a CME passes the Moon to the ambient conditions. Here, we compare model results to data in order to determine the source rates and surface interaction parameters that provide the best fit of the model to the data.

Shadows and Dust: Mid-Infrared Extinction Mapping of the Initial Conditions of Massive Star and Star Cluster Formation

NASA Astrophysics Data System (ADS)

Tan, Jonathan

We describe a research plan to develop and extend the mid-infrared (MIR) extinction mapping technique presented by Butler & Tan (2009), who studied Infrared Dark Clouds (IRDCs) using Spitzer Space Telescope Infrared Array Camera (IRAC) 8 micron images. This method has the ability to probe the detailed spatial structure of very high column density regions, i.e. the gas clouds thought to represent the initial conditions for massive star and star cluster formation. We will analyze the data Spitzer obtained at other wavelengths, i.e. the IRAC bands at 3.6, 4.5 and 5.8 microns, and the Multiband Imaging Photometer (MIPS) bands, especially at 24 microns. This will allow us to measure the dust extinction law across the MIR and search for evidence of dust grain evolution, e.g. grain growth and ice mantle formation, as a function of gas density and column density. We will also study the detailed structure of the extinction features, including individual cores that may form single stars or close binaries, especially focusing on those cores that may form massive stars. By studying independent dark cores in a given IRDC, we will be able to test if they have a common minimum observed intensity, which we will then attribute to the foreground. This is a new method that should allow us to more accurately map distant, high column density IRDCs, probing more extreme regimes of star formation. We will combine MIR extinction mapping, which works best at high column densities, with near- IR mapping based on 2MASS images of star fields, which is most useful at lower columns that probe the extended giant molecular cloud structure. This information is crucial to help understand the formation process of IRDCs, which may be the rate limiting step for global galactic star formation rates. We will use our new extinction mapping methods to analyze large samples of IRDCs and thus search the Galaxy for the most extreme examples of high column density cores and assess the global star formation efficiency in dense gas. We will estimate the ability of future NASA missions, such as JWST, to carry out MIR extinction mapping science. We will develop the results of this research into an E/PO presentation to be included in the various public outreach events organized and courses taught by the PI.

Achieving High-Energy-High-Power Density in a Flexible Quasi-Solid-State Sodium Ion Capacitor.

PubMed

Li, Hongsen; Peng, Lele; Zhu, Yue; Zhang, Xiaogang; Yu, Guihua

2016-09-14

Simultaneous integration of high-energy output with high-power delivery is a major challenge for electrochemical energy storage systems, limiting dual fine attributes on a device. We introduce a quasi-solid-state sodium ion capacitor (NIC) based on a battery type urchin-like Na2Ti3O7 anode and a capacitor type peanut shell derived carbon cathode, using a sodium ion conducting gel polymer as electrolyte, achieving high-energy-high-power characteristics in solid state. Energy densities can reach 111.2 Wh kg(-1) at power density of 800 W kg(-1), and 33.2 Wh kg(-1) at power density of 11200 W kg(-1), which are among the best reported state-of-the-art NICs. The designed device also exhibits long-term cycling stability over 3000 cycles with capacity retention ∼86%. Furthermore, we demonstrate the assembly of a highly flexible quasi-solid-state NIC and it shows no obvious capacity loss under different bending conditions.

[Dependence of ion transport across the plasma membrane on the density of the cell culture. I. Ion flows and the potassium and sodium content in 3 Chinese hamster cell lines (CHO)].

PubMed

Marakhova, I I; Pospelova, T V; Vinogradova, T A; Vereninov, A A; Ignatova, T N

1985-09-01

Cation transport has been investigated in three lines of Chinese ovary cells CHO-K1 during the cell culture growth. With the increase in the cell density potassium and sodium contents decreased from 1.2 to 0.8-0.5 and from 0.5 to 0.15-0.1 mmole/g protein, respectively. The time courses of potassium and sodium changes were different, and the increase in intracellular K/Na ratio from 1.5-2.0 to 5-10 with the increase in cell density was revealed. The rubidium influx was found to decrease during the culture growth mainly due to the decrease in ouabain-inhibitable and (ouabain + furosemide)- non-inhibitable influxes. The changes in cation fluxes and cation contents were observed in transformed cells without contact inhibition of division and were considered as a manifestation of density-dependent alterations of plasma membrane.

Cosmic distribution of highly ionized metals and their physical conditions in the EAGLE simulations

NASA Astrophysics Data System (ADS)

Rahmati, Alireza; Schaye, Joop; Crain, Robert A.; Oppenheimer, Benjamin D.; Schaller, Matthieu; Theuns, Tom

2016-06-01

We study the distribution and evolution of highly ionized intergalactic metals in the Evolution and Assembly of Galaxies and their Environment (EAGLE) cosmological, hydrodynamical simulations. EAGLE has been shown to reproduce a wide range of galaxy properties while its subgrid feedback was calibrated without considering gas properties. We compare the predictions for the column density distribution functions (CDDFs) and cosmic densities of Si IV, C IV, N V, O VI and Ne VIII absorbers with observations at redshift z = 0 to ˜6 and find reasonable agreement, although there are some differences. We show that the typical physical densities of the absorbing gas increase with column density and redshift, but decrease with the ionization energy of the absorbing ion. The typical metallicity increases with both column density and time. The fraction of collisionally ionized metal absorbers increases with time and ionization energy. While our results show little sensitivity to the presence or absence of AGN feedback, increasing/decreasing the efficiency of stellar feedback by a factor of 2 substantially decreases/increases the CDDFs and the cosmic densities of the metal ions. We show that the impact of the efficiency of stellar feedback on the CDDFs and cosmic densities is largely due to its effect on the metal production rate. However, the temperatures of the metal absorbers, particularly those of strong O VI, are directly sensitive to the strength of the feedback.

An analysis of OH excited state absorption lines in DR 21 and K3-50

NASA Astrophysics Data System (ADS)

Jones, K. N.; Doel, R. C.; Field, D.; Gray, M. D.; Walker, R. N. F.

1992-10-01

We present an analysis of the OH absorption line zones observed toward the compact H II regions DR 21 and K3-50. Using as parameters the kinetic and dust temperatures, the H2 number density and the ratio of OH-H2 number densities to the velocity gradient, the model quantitatively reproduces the absorption line data for the six main line transitions in 2 Pi3/2 J = 5/2, 7/2, and 9/2. Observed upper limits for the absorption or emission in the satellite lines of 2 Pi3/2 J = 5/2 are crucial in constraining the range of derived parameters. Physical conditions derived for DR 21 show that the kinetic temperature centers around 140 K, the H2 number density around 10 exp 7/cu cm, and that the OH column density in the excited state absorption zone lies between 1 x 10 exp 15/sq cm and 2 x 10 exp 15/sq cm. Including contributions from a J = 3/2 absorption zone, the total OH column density is more than a factor of 2 lower than estimates based upon LTE (Walmsley et al., 1986). The OH absorption zone in K3-50 tends toward higher density and displays a larger column density, while the kinetic temperature is similar. For both sources, the dust temperature is found to be significantly lower than the kinetic temperature.

Synthesis and characterization of nanometric zinc oxide for a stationary phase in liquid chromatography

NASA Astrophysics Data System (ADS)

Gordillo-Delgado, F.; Soto-Barrera, C. C.; Plazas-Saldaña, J.

2017-01-01

The increasing demand for equipment to remove organic compounds in industry and research activity has led to evaluate nanometric zinc oxide (ZnO). In this work, we present the ZnO nanoparticles synthesis for reusing of discarded columns, as a low-cost alternative. The compound was obtained by sol-gel technique using zinc chloride and sodium hydroxide as precursors and a drying temperature of 169°C. An X-ray diffractometer was used to estimate the average particle size at 20.3±0.2nm the adsorption capacity was 0.0144L/g and the chemical resistance was tested with HCl and NaOH. The ZnO nanopowder was packed with 100psi pressure in an empty C-18 column cavity. The column packing resolution was evaluated using a high performance liquid chromatographer (HPLC-Thermo Scientific Dionex UltiMate 3000); using a caffeine standard, the following parameters were established: solvent flow: 1.2mL/min, average column temperature: 40°C, running time: 10 minutes, mobile phase acetonitrile-water composition (9:1). These results validate the potential of ZnO nanopowder as a column packing material in HPLC technique.

Sodium content in packaged foods by census division in the United States, 2009.

PubMed

Lee, Alexandra K; Schieb, Linda J; Yuan, Keming; Maalouf, Joyce; Gillespie, Cathleen; Cogswell, Mary E

2015-04-02

Excess sodium intake correlates positively with high blood pressure. Blood pressure varies by region, but whether sodium content of foods sold varies across regions is unknown. We combined nutrition and sales data from 2009 to assess the regional variation of sodium in packaged food products sold in 3 of the 9 US census divisions. Although sodium density and concentration differed little by region, fewer than half of selected food products met Food and Drug Administration sodium-per-serving conditions for labeling as "healthy." Regional differences in hypertension were not reflected in differences in the sodium content of packaged foods from grocery stores.

Characterizing the plasma of the Rotating Wall Machine

NASA Astrophysics Data System (ADS)

Hannum, David A.

The Rotating Wall Machine (RoWM) is a line-tied linear screw pinch built to study current-driven external kink modes. The plasma column is formed by an array of seven electrostatic washer guns which can also be biased to drive plasma current. The array allows independent control over the electron density ne and current density Jz profiles of the column. Internal measurements of the plasma have been made with singletip Langmuir and magnetic induction ("B-dot") probes for a range of bias currents (Ib = 0, 300, 500 A/gun). Streams from the individual guns are seen to merge at a distance of z ≈ 36 cm from the guns; the exact distance depends on the value of Ib. The density of the column is directly proportional to the Ohmic dissipation power, but the temperature stays at a low, uniform value (Te ≈ 3.5 eV) for each bias level. Electron densities are on the order of ne ˜10 20 m-3. The electron density expands radially (across the Bz guide field) as the plasma moves along the column, though the current density Jz mainly stays parallel to the field lines. The singletip Langmuir probe diagnostic is difficult to analyze for Ib = 500 A/gun plasmas and fails as Ib is raised beyond this level. Spectrographic analysis of the Halpha line indicates that the hydrogen plasmas are nearly fully ionized at each bias level. Azimuthal E x B rotation is axially and radially sheared; rotation slows as the plasma reaches the anode. Perpendicular diffusivity is consistent with the classical value, D⊥ ≈ 5 m2/sec, while parallel resistivity is seen to be twice the classical Spitzer value, 2 x 10-4 O m.

Interstellar Deuterium, Nitrogen and Oxygen Towards HZ43A: Results from the Far Ultraviolet Spectroscopic Explorer (FUSE) Mission

NASA Technical Reports Server (NTRS)

Kruk, J. W.; Howk, J. C.; Andre, M.; Moos, H. W.; Oegerle, William R.; Oliveira, C.; Sembach, K. R.; Chayer, P.; Linsky, J. L.; Wood, B. E.

2002-01-01

We present an analysis of interstellar absorption along the line of sight to the nearby white dwarf star HZ43A. The distance to this star is 68+/-13 pc, and the line of sight extends toward the north Galactic pole. Column densities of O(I), N(I), and N(II) were derived from spectra obtained by the Far Ultraviolet Spectroscopic Explorer (FUSE), the column density of D(I) was derived from a combination of our FUSE spectra and an archival HST GARDENS spectrum, and the column density of H(I) was derived from a combination of the GARDENS spectrum and values derived from EUVE data obtained from the literature. We find the following abundance ratios (with 2 sigma uncertainties): D(I)/H(I)=(1.66+/-0.28)x10(exp -5), O(I)/H(I)=(3.63+/-0.84)x10(exp -4), and N(I)/H(I)=(3.80+/-0.74)x10(exp -5). The N(II) column density was slightly greater than that of N(I), indicating that ionization corrections are important when deriving nitrogen abundances. Other interstellar species detected along the line of sight were C(II), C(III), O(VI), Si(II), Ar(I), Mg(II) and Fe(II); an upper limit was determined for N(III). No elements other than H(I) were detected in the stellar photosphere.

Probing the local environment of the supernova remnant HESS J1731-347 with CO and CS observations

NASA Astrophysics Data System (ADS)

Maxted, N.; Burton, M.; Braiding, C.; Rowell, G.; Sano, H.; Voisin, F.; Capasso, M.; Pühlhofer, G.; Fukui, Y.

2018-02-01

The shell-type supernova remnant HESS J1731 - 347 emits TeV gamma-rays, and is a key object for the study of the cosmic ray acceleration potential of supernova remnants. We use 0.5-1 arcmin Mopra CO/CS(1-0) data in conjunction with H I data to calculate column densities towards the HESS J1731 - 347 region. We trace gas within at least four Galactic arms, typically tracing total (atomic+molecular) line-of-sight H column densities of 2-3× 1022 cm-2. Assuming standard X-factor values and that most of the H I/CO emission seen towards HESS J1731 - 347 is on the near-side of the Galaxy, X-ray absorption column densities are consistent with H I+CO-derived column densities foreground to, but not beyond, the Scutum-Crux Galactic arm, suggesting a kinematic distance of ˜3.2 kpc for HESS J1731 - 347. At this kinematic distance, we also find dense, infrared-dark gas traced by CS(1-0) emission coincident with the north of HESS J1731 - 347, the nearby H II region G353.43-0.37 and the nearby unidentified gamma-ray source HESS J1729 - 345. This dense gas lends weight to the idea that HESS J1729 - 345 and HESS J1731 - 347 are connected, perhaps via escaping cosmic-rays.

Intra-pixel variability in satellite tropospheric NO2 column densities derived from simultaneous space-borne and airborne observations over the South African Highveld

NASA Astrophysics Data System (ADS)

Broccardo, Stephen; Heue, Klaus-Peter; Walter, David; Meyer, Christian; Kokhanovsky, Alexander; van der A, Ronald; Piketh, Stuart; Langerman, Kristy; Platt, Ulrich

2018-05-01

Aircraft measurements of NO2 using an imaging differential optical absorption spectrometer (iDOAS) instrument over the South African Highveld region in August 2007 are presented and compared to satellite measurements from OMI and SCIAMACHY. In situ aerosol and trace-gas vertical profile measurements, along with aerosol optical thickness and single-scattering albedo measurements from the Aerosol Robotic Network (AERONET), are used to devise scenarios for a radiative transfer modelling sensitivity study. Uncertainty in the air-mass factor due to variations in the aerosol and NO2 profile shape is constrained and used to calculate vertical column densities (VCDs), which are compared to co-located satellite measurements. The lower spatial resolution of the satellites cannot resolve the detailed plume structures revealed in the aircraft measurements. The airborne DOAS in general measured steeper horizontal gradients and higher peak NO2 vertical column density. Aircraft measurements close to major sources, spatially averaged to the satellite resolution, indicate NO2 column densities more than twice those measured by the satellite. The agreement between the high-resolution aircraft instrument and the satellite instrument improves with distance from the source, this is attributed to horizontal and vertical dispersion of NO2 in the boundary layer. Despite the low spatial resolution, satellite images reveal point sources and plumes that retain their structure for several hundred kilometres downwind.

Retrieval of tropospheric HCHO in El Salvador using ground based DOAS

NASA Astrophysics Data System (ADS)

Abarca, W.; Gamez, K.; Rudamas, C.

2017-12-01

Formaldehyde (HCHO) is the most abundant carbonyl in the atmosphere, being an intermediate product in the oxidation of most volatile organic compounds (VOCs). HCHO is carcinogenic, and highly water soluble [1]. HCHO can originate from biomass burning and fossil fuel combustion and has been observed from satellite and ground-based sensors by using the Differential Optical Absorption Spectroscopy (DOAS) technique [2].DOAS products can be used for air quality monitoring, validation of chemical transport models, validation of satellite tropospheric column density retrievals, among others [3]. In this study, we report on column density levels of HCHO measured by ground based Multi-Axis -DOAS in different locations of El Salvador in March, 2015. We have not observed large differences of the HCHO column density values at different viewing directions. This result points out a reasonably polluted and hazy atmosphere in the measuring sites, as reported by other authors [4]. Average values ranging from 1016 to 1017 molecules / cm2 has been obtained. The contribution of vehicular traffic and biomass burning to the column density levels in these sites of El Salvador will be discussed. [1] A. R. Garcia et al., Atmos. Chem. Phys. 6, 4545 (2006) [2] E. Peters et al., Atmos. Chem. Phys. 12, 11179 (2012) [3] T. Vlemmix, et al. Atmos. Meas. Tech., 8, 941-963, 2015 [4] A. Heckel et al., Atmos. Chem. Phys. 5, (2005)

Hot and cold gas toward young stellar objects

NASA Technical Reports Server (NTRS)

Mitchell, George F.; Maillard, Jean-Pierre; Allen, Mark; Beer, Reinhard; Belcourt, Kenneth

1990-01-01

High-resolution M band spectra are presented for the seven embedded IR sources W3 IRS 5, S140 IRS1, NGC 7538 IRS 1, NGC 7538 IRS 9, GL 2136, LkH-alpha 101, and MWC 349A, and the data are combined with previously published work for W33A and GL 2591. Cold CO is seen toward all nine sources, with temperatures from 11 K to 66 K. Column densities of cold CO are presented. Hot gas is seen toward eight of the nine objects with temperatures from 120 K to 1010 K. New lower limits to the hot gas density are obtained. The hot gas toward GL 2591, GL 2136, W3 IRS 5, and S140 IRS 1 is probably very near the central source and heated via gas-grain collisions. The optical depth in the silicate feature is strongly correlated with the (C-13)O column density, confirming that silicate optical depth is a useful measure of gas column density. The ratio of solid-to-gaseous CO is obtained for seven sources.

Characteristic Structure of Star-forming Clouds

NASA Astrophysics Data System (ADS)

Myers, Philip C.

2015-06-01

This paper presents a new method to diagnose the star-forming potential of a molecular cloud region from the probability density function of its column density (N-pdf). This method provides expressions for the column density and mass profiles of a symmetric filament having the same N-pdf as a filamentary region. The central concentration of this characteristic filament can distinguish regions and can quantify their fertility for star formation. Profiles are calculated for N-pdfs which are pure lognormal, pure power law, or a combination. In relation to models of singular polytropic cylinders, characteristic filaments can be unbound, bound, or collapsing depending on their central concentration. Such filamentary models of the dynamical state of N-pdf gas are more relevant to star-forming regions than are spherical collapse models. The star formation fertility of a bound or collapsing filament is quantified by its mean mass accretion rate when in radial free fall. For a given mass per length, the fertility increases with the filament mean column density and with its initial concentration. In selected regions the fertility of their characteristic filaments increases with the level of star formation.

Sodium-metal chloride batteries

NASA Technical Reports Server (NTRS)

Ratnakumar, B. V.; Attia, A. I.; Halpert, G.

1992-01-01

It was concluded that rapid development in the technology of sodium metal chloride batteries has been achieved in the last decade mainly due to the: expertise available with sodium sulfur system; safety; and flexibility in design and fabrication. Long cycle lives of over 1000 and high energy densities of approx. 100 Wh/kg have been demonstrated in both Na/FeCl2 and Na/NiCl2 cells. Optimization of porous cathode and solid electrolyte geometries are essential for further enhancing the battery performance. Fundamental studies confirm the capabilities of these systems. Nickel dichloride emerges as the candidate cathode material for high power density applications such as electric vehicle and space.

Ionization compression impact on dense gas distribution and star formation. Probability density functions around H II regions as seen by Herschel

NASA Astrophysics Data System (ADS)

Tremblin, P.; Schneider, N.; Minier, V.; Didelon, P.; Hill, T.; Anderson, L. D.; Motte, F.; Zavagno, A.; André, Ph.; Arzoumanian, D.; Audit, E.; Benedettini, M.; Bontemps, S.; Csengeri, T.; Di Francesco, J.; Giannini, T.; Hennemann, M.; Nguyen Luong, Q.; Marston, A. P.; Peretto, N.; Rivera-Ingraham, A.; Russeil, D.; Rygl, K. L. J.; Spinoglio, L.; White, G. J.

2014-04-01

Aims: Ionization feedback should impact the probability distribution function (PDF) of the column density of cold dust around the ionized gas. We aim to quantify this effect and discuss its potential link to the core and initial mass function (CMF/IMF). Methods: We used Herschel column density maps of several regions observed within the HOBYS key program in a systematic way: M 16, the Rosette and Vela C molecular clouds, and the RCW 120 H ii region. We computed the PDFs in concentric disks around the main ionizing sources, determined their properties, and discuss the effect of ionization pressure on the distribution of the column density. Results: We fitted the column density PDFs of all clouds with two lognormal distributions, since they present a "double-peak" or an enlarged shape in the PDF. Our interpretation is that the lowest part of the column density distribution describes the turbulent molecular gas, while the second peak corresponds to a compression zone induced by the expansion of the ionized gas into the turbulent molecular cloud. Such a double peak is not visible for all clouds associated with ionization fronts, but it depends on the relative importance of ionization pressure and turbulent ram pressure. A power-law tail is present for higher column densities, which are generally ascribed to the effect of gravity. The condensations at the edge of the ionized gas have a steep compressed radial profile, sometimes recognizable in the flattening of the power-law tail. This could lead to an unambiguous criterion that is able to disentangle triggered star formation from pre-existing star formation. Conclusions: In the context of the gravo-turbulent scenario for the origin of the CMF/IMF, the double-peaked or enlarged shape of the PDF may affect the formation of objects at both the low-mass and the high-mass ends of the CMF/IMF. In particular, a broader PDF is required by the gravo-turbulent scenario to fit the IMF properly with a reasonable initial Mach number for the molecular cloud. Since other physical processes (e.g., the equation of state and the variations among the core properties) have already been said to broaden the PDF, the relative importance of the different effects remains an open question. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.

Quasi-Solid-State Sodium-Ion Full Battery with High-Power/Energy Densities.

PubMed

Guo, Jin-Zhi; Yang, Ai-Bo; Gu, Zhen-Yi; Wu, Xing-Long; Pang, Wei-Lin; Ning, Qiu-Li; Li, Wen-Hao; Zhang, Jing-Ping; Su, Zhong-Min

2018-05-30

Developing a high-performance, low-cost, and safer rechargeable battery is a primary challenge in next-generation electrochemical energy storage. In this work, a quasi-solid-state (QSS) sodium-ion full battery (SIFB) is designed and fabricated. Hard carbon cloth derived from cotton cloth and Na 3 V 2 (PO 4 ) 2 O 2 F (NVPOF) are employed as the anode and the cathode, respectively, and a sodium ion-conducting gel-polymer membrane is used as both the QSS electrolyte and separator, accomplishing the high energy and power densities in the QSS sodium-ion batteries. The energy density can reach 460 W h kg -1 according to the mass of the cathode materials. Moreover, the fabricated QSS SIFB also exhibits an excellent rate performance (e.g., about 78.1 mA h g -1 specific capacity at 10 C) and a superior cycle performance (e.g., ∼90% capacity retention after 500 cycles at 10 C). These results show that the developed QSS SIFB is a hopeful candidate for large-scale energy storage.

A novel RP-HPLC method for simultaneous determination of potassium sorbate and sodium benzoate in soft drinks using C18-bonded monolithic silica column.

PubMed

Can, Nafiz O; Arli, Goksel; Lafci, Yigit

2011-08-01

Potassium sorbate and sodium benzoate are food additives that are generally employed for prevention of food spoilage originating from bacteria, molds or yeasts. Although these compounds were generally recognized as safe due to their low risk of acute and chronic toxicity, they have limitations of usage to protect human health. Development and validation of a novel RP-HPLC method, in which a C18-bonded monolithic silica column was used as stationary phase to assay these compounds, is described for the first time. Aliquots of 10 μL of samples were injected into chromatograph and eluted using phosphate buffer (0.025 M, pH 2.0)-water-acetonitrile (50:45:5, v/v/v) solution, which was pumped at the rate of 3.0 mL/min. To sharpen the peaks, 10 mM octylamine was added to the mobile phase. Potassium sorbate and sodium benzoate were detected at about 12(th) and 14(th) min, respectively, and quantified at 230 nm using photodiode array detector. A total of 41 samples were prepared by simply filtering through 0.45 μm filters after sonication, and injected into the system without any pre-treatment steps. Applicability of the method was demonstrated by performing total procedure on samples of different brands and types, and their compliance to official regulations was assessed. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A RP-HPLC method for quantification of diclofenac sodium released from biological macromolecules.

PubMed

Bhattacharya, Shiv Sankar; Banerjee, Subham; Ghosh, Ashoke Kumar; Chattopadhyay, Pronobesh; Verma, Anurag; Ghosh, Amitava

2013-07-01

Interpenetrating network (IPN) microbeads of sodium carboxymethyl locust bean gum (SCMLBG) and sodium carboxymethyl cellulose (SCMC) containing diclofenac sodium (DS), a nonsteroidal anti-inflammatory drug, were prepared by single water-in-water (w/w) emulsion gelation process using AlCl3 as cross-linking agent in a complete aqueous environment. Pharmacokinetic study of these IPN microbeads was then carried out by a simple and feasible high-performance liquid chromatographic method with UV detection which was developed and validated for the quantification of diclofenac sodium in rabbit plasma. The chromatographic separation was carried out in a Hypersil BDS, C18 column (250 mm × 4.6 mm; 5 m). The mobile phase was a mixture of acetonitrile and methanol (70:30, v/v) at a flow rate of 1.0 ml/min. The UV detection was set at 276 nm. The extraction recovery of diclofenac sodium in plasma of three quality control (QC) samples was ranged from 81.52% to 95.29%. The calibration curve was linear in the concentration range of 20-1000 ng/ml with the correlation coefficient (r(2)) above 0.9951. The method was specific and sensitive with the limit of quantification of 20 ng/ml. In stability tests, diclofenac sodium in rabbit plasma was stable during storage and assay procedure. Copyright © 2013. Published by Elsevier B.V.

Effect of surfactant on single drop mass transfer for extraction of aromatics from lubricating oils

NASA Astrophysics Data System (ADS)

Izza, H.; Ben Abdessalam, S.; Korichi, M.

2018-03-01

Solvent extraction is an effective method for the reduction of the content of aromatic of lubricating oil. Frequently, with phenol, furfural, the NMP (out of N-methyl pyrrolidone). The power solvent and the selectivity can be still to increase while using surfactant as additive which facilitates the separation of phase and increases the yeild in raffinat. Liquid-liquid mass transfer coefficients for single freely rising drops in the presence of surfactant in an extraction column have been investigated. The surfactant used in this study was sodium lauryl ether sulfate (SLES). The experiments were performed by bubbling a solvent as a series of individual drops from the top of the column containing furfural-SLES solution. The column used in this experiment was made from glass with 17 mm inner diameter and a capacity of 125ml. The effects of the concentration of surfactant on the overall coefficient of mass transfer was investigated.

40 CFR Table Mm-2 to Subpart Mm of... - Default Factors for Biomass-Based Fuels and Biomass

Code of Federal Regulations, 2011 CFR

2011-07-01

... Fuels and Biomass MM Table MM-2 to Subpart MM of Part 98 Protection of Environment ENVIRONMENTAL... Biomass-Based Fuels and Biomass Biomass-based fuel and biomass Column A:Density (metric tons/bbl) Column B: Carbon share(% of mass) Column C:Emission factor (metric tons CO2/bbl) Ethanol (100%) 0.1267 52.14 0.2422...

40 CFR Table Mm-2 to Subpart Mm of... - Default Factors for Biomass-Based Fuels and Biomass

Code of Federal Regulations, 2013 CFR

2013-07-01

... Fuels and Biomass MM Table MM-2 to Subpart MM of Part 98 Protection of Environment ENVIRONMENTAL... Biomass-Based Fuels and Biomass Biomass-based fuel and biomass Column A:Density (metric tons/bbl) Column B: Carbon share(% of mass) Column C:Emission factor (metric tons CO2/bbl) Ethanol (100%) 0.1267 52.14 0.2422...

40 CFR Table Mm-2 to Subpart Mm of... - Default Factors for Biomass-Based Fuels and Biomass

Code of Federal Regulations, 2014 CFR

2014-07-01

... Fuels and Biomass MM Table MM-2 to Subpart MM of Part 98 Protection of Environment ENVIRONMENTAL... Biomass-Based Fuels and Biomass Biomass-based fuel and biomass Column A:Density (metric tons/bbl) Column B: Carbon share(% of mass) Column C:Emission factor (metric tons CO2/bbl) Ethanol (100%) 0.1267 52.14 0.2422...

40 CFR Table Mm-2 to Subpart Mm of... - Default Factors for Biomass-Based Fuels and Biomass

Code of Federal Regulations, 2012 CFR

2012-07-01

... Fuels and Biomass MM Table MM-2 to Subpart MM of Part 98 Protection of Environment ENVIRONMENTAL... Biomass-Based Fuels and Biomass Biomass-based fuel and biomass Column A:Density (metric tons/bbl) Column B: Carbon share(% of mass) Column C:Emission factor (metric tons CO2/bbl) Ethanol (100%) 0.1267 52.14 0.2422...

Abundances of Deuterium, Oxygen and Nitrogen in the Local Interstellar Medium: Overview of First Results from the Far Ultraviolet Spectroscopic Explorer Mission

NASA Technical Reports Server (NTRS)

Moos, H. W.; Sembach, K. R.; Vidal-Madjar, A.; York, D. G.; Friedman, S. D.; Hebrard, G.; Kruk, J. W.; Lehner, N.; Lemoine, M.; Sonneborn, G.;

Deuterium Abundance Toward G191-B2B: Results from the Far Ultraviolet Spectroscopic Explorer (FUSE) Mission

NASA Technical Reports Server (NTRS)

Lemoine, M.; Vidal-Madjar, A.; Hebrard, G.; Desert, J.-M.; Ferlet, R.; LecavelierdesEtangs, A.; Howk, J. C.; Andre, M.; Blair, W. P.; Friedman, S. D.;

The abundance, distribution, and physical nature of highly ionized oxygen O VI, O VII, and O VIII in IllustrisTNG

NASA Astrophysics Data System (ADS)

Nelson, Dylan; Kauffmann, Guinevere; Pillepich, Annalisa; Genel, Shy; Springel, Volker; Pakmor, Rüdiger; Hernquist, Lars; Weinberger, Rainer; Torrey, Paul; Vogelsberger, Mark; Marinacci, Federico

2018-06-01

We explore the abundance, spatial distribution, and physical properties of the O VI, O VII, and O VIII ions of oxygen in circumgalactic and intergalactic media (the CGM, IGM, and WHIM). We use the TNG100 and TNG300 large volume cosmological magnetohydrodynamical simulations. Modelling the ionization states of simulated oxygen, we find good agreement with observations of the low-redshift O VI column density distribution function (CDDF), and present its evolution for all three ions from z = 0 to z = 4. Producing mock quasar absorption line spectral surveys, we show that the IllustrisTNG simulations are fully consistent with constraints on the O VI content of the CGM from COS-haloes and other low-redshift observations, producing columns as high as observed. We measure the total amount of mass and average column densities of each ion using hundreds of thousands of simulated galaxies spanning 10^{11} < {M}_halo/ M⊙<1015 corresponding to 109 < M⋆/ M⊙<1012 in stellar mass. Stacked radial profiles of O VI are computed in 3D number density and 2D projected column density, decomposing into 1-halo and 2-halo terms. Relating halo O VI to properties of the central galaxy, we find a correlation between the (g - r) colour of a galaxy and the total amount of O VI in its CGM. In comparison to the COS-Haloes finding, this leads to a dichotomy of columns around star-forming versus passive galaxies at fixed stellar (or halo) mass. We demonstrate that this correlation is a direct result of black hole feedback associated with quenching and represents a causal consequence of galactic-scale baryonic feedback impacting the physical state of the circumgalactic medium.

Visualization and simulation of density driven convection in porous media using magnetic resonance imaging.

PubMed

Montague, James A; Pinder, George F; Gonyea, Jay V; Hipko, Scott; Watts, Richard

2018-05-01

Magnetic resonance imaging is used to observe solute transport in a 40cm long, 26cm diameter sand column that contained a central core of low permeability silica surrounded by higher permeability well-sorted sand. Low concentrations (2.9g/L) of Magnevist, a gadolinium based contrast agent, produce density driven convection within the column when it starts in an unstable state. The unstable state, for this experiment, exists when higher density contrast agent is present above the lower density water. We implement a numerical model in OpenFOAM to reproduce the observed fluid flow and transport from a density difference of 0.3%. The experimental results demonstrate the usefulness of magnetic resonance imaging in observing three-dimensional gravity-driven convective-dispersive transport behaviors in medium scale experiments. Copyright © 2017 Elsevier B.V. All rights reserved.

Vanadyl phosphates as high energy density cathode materials for rechargeable sodium battery

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Ruigang; Mizuno, Fuminori; Ling, Chen

A positive electrode comprising .epsilon.-VOPO.sub.4 and/or Na.sub.x(.epsilon.-VOPO.sub.4) wherein x is a value from 0.1 to 1.0 as an active ingredient, wherein the electrode is capable of insertion and release of sodium ions and a reversible sodium battery containing the positive electrode are provided.

Suspension of Drops of a Liquid in a Column of Water.

ERIC Educational Resources Information Center

Ahmad, Jamil

1995-01-01

Describes a demonstration which creates the illusion of violating Archimedes Principle. The procedure involves two liquids with identical densities and produces drops of one liquid suspended in the middle of a column of the second liquid. (DDR)

Changes of Dust Opacity with Density in the Orion A Molecular Cloud

NASA Astrophysics Data System (ADS)

Roy, Arabindo; Martin, Peter G.; Polychroni, Danae; Bontemps, Sylvain; Abergel, Alain; André, Philippe; Arzoumanian, Doris; Di Francesco, James; Hill, Tracey; Konyves, Vera; Nguyen-Luong, Quang; Pezzuto, Stefano; Schneider, Nicola; Testi, Leonardo; White, Glenn

2013-01-01

We have studied the opacity of dust grains at submillimeter wavelengths by estimating the optical depth from imaging at 160, 250, 350, and 500 μm from the Herschel Gould Belt Survey and comparing this to a column density obtained from the Two Micron All Sky Survey derived color excess E(J - K s). Our main goal was to investigate the spatial variations of the opacity due to "big" grains over a variety of environmental conditions and thereby quantify how emission properties of the dust change with column (and volume) density. The central and southern areas of the Orion A molecular cloud examined here, with N H ranging from 1.5 × 1021 cm-2 to 50 × 1021 cm-2, are well suited to this approach. We fit the multi-frequency Herschel spectral energy distributions (SEDs) of each pixel with a modified blackbody to obtain the temperature, T, and optical depth, τ1200, at a fiducial frequency of 1200 GHz (250 μm). Using a calibration of N H/E(J - Ks ) for the interstellar medium (ISM) we obtained the opacity (dust emission cross-section per H nucleon), σe(1200), for every pixel. From a value ~1 × 10-25 cm2 H-1 at the lowest column densities that is typical of the high-latitude diffuse ISM, σe(1200) increases as N 0.28 H over the range studied. This is suggestive of grain evolution. Integrating the SEDs over frequency, we also calculated the specific power P (emission power per H) for the big grains. In low column density regions where dust clouds are optically thin to the interstellar radiation field (ISRF), P is typically 3.7 × 10-31 W H-1, again close to that in the high-latitude diffuse ISM. However, we find evidence for a decrease of P in high column density regions, which would be a natural outcome of attenuation of the ISRF that heats the grains, and for localized increases for dust illuminated by nearby stars or embedded protostars.

High-performance liquid chromatography-electrospray ionization mass spectrometry determination of sodium ferulate in human plasma.

PubMed

Yang, Cheng; Tian, Yuan; Zhang, Zunjian; Xu, Fengguo; Chen, Yun

2007-02-19

A selective and sensitive high-performance liquid chromatography-electrospray ionization mass spectrometry method has been developed for the determination of sodium ferulate in human plasma. The sample preparation was a liquid-liquid extraction and chromatographic separation was achieved with an Agilent ZORBAX SB-C(18) (3.5 microm, 100 mm x 3.0 mm) column, using a mobile phase of methanol-0.05% acetic acid 40:60 (v/v). Standard curves were linear (r(2)=0.9982) over the concentration range of 0.007-4.63 nM/ml and had acceptable accuracy and precision. The within- and between-batch precisions were within 12% relative standard deviation. The lower limit of quantification (LLOQ) was 0.007 nM/ml. The validated HPLC-ESI-MS method has been used successfully to study sodium ferulate pharmacokinetics, bioavailability and bioequivalence in 20 healthy volunteers.

Quantitative estimation of itopride hydrochloride and rabeprazole sodium from capsule formulation.

PubMed

Pillai, S; Singhvi, I

2008-09-01

Two simple, accurate, economical and reproducible UV spectrophotometric methods and one HPLC method for simultaneous estimation of two component drug mixture of itopride hydrochloride and rabeprazole sodium from combined capsule dosage form have been developed. First developed method involves formation and solving of simultaneous equations using 265.2 nm and 290.8 nm as two wavelengths. Second method is based on two wavelength calculation, wavelengths selected for estimation of itopride hydrochloride was 278.0 nm and 298.8 nm and for rabeprazole sodium 253.6 nm and 275.2 nm. Developed HPLC method is a reverse phase chromatographic method using phenomenex C(18) column and acetonitrile: phosphate buffer (35:65 v/v) pH 7.0 as mobile phase. All developed methods obey Beer's law in concentration range employed for respective methods. Results of analysis were validated statistically and by recovery studies.

Quantitative Estimation of Itopride Hydrochloride and Rabeprazole Sodium from Capsule Formulation

PubMed Central

Pillai, S.; Singhvi, I.

2008-01-01

Two simple, accurate, economical and reproducible UV spectrophotometric methods and one HPLC method for simultaneous estimation of two component drug mixture of itopride hydrochloride and rabeprazole sodium from combined capsule dosage form have been developed. First developed method involves formation and solving of simultaneous equations using 265.2 nm and 290.8 nm as two wavelengths. Second method is based on two wavelength calculation, wavelengths selected for estimation of itopride hydrochloride was 278.0 nm and 298.8 nm and for rabeprazole sodium 253.6 nm and 275.2 nm. Developed HPLC method is a reverse phase chromatographic method using phenomenex C18 column and acetonitrile: phosphate buffer (35:65 v/v) pH 7.0 as mobile phase. All developed methods obey Beer's law in concentration range employed for respective methods. Results of analysis were validated statistically and by recovery studies. PMID:21394269

High-capacity cation-exchange column for enhanced resolution of adjacent peaks of cations in ion chromatography.

PubMed

Rey, M A

2001-06-22

One of the advantages of ion chromatography [Anal Chem. 47 (1975) 1801] as compared to other analytical techniques is that several ions may be analyzed simultaneously. One of the most important contributions of cation-exchange chromatography is its sensitivity to ammonium ion, which is difficult to analyze by other techniques [J. Weiss, in: E.L. Johnson (Ed.), Handbook of Ion Chromatography, Dionex, Sunnyvale, CA, USA]. The determination of low concentrations of ammonium ion in the presence of high concentrations of sodium poses a challenge in cation-exchange chromatography [J. Weiss, Ion Chromatography, VCH, 2nd Edition, Weinheim, 1995], as both cations have similar selectivities for the common stationary phases containing either sulfonate or carboxylate functional groups. The task was to develop a new cation-exchange stationary phase (for diverse concentration ratios of adjacent peaks) to overcome limitations experienced in previous trails. Various cation-exchange capacities and column body formats were investigated to optimize this application and others. The advantages and disadvantages of two carboxylic acid columns of different cation-exchange capacities and different column formats will be discussed.

Tracing and separating plasma components causing matrix effects in hydrophilic interaction chromatography-electrospray ionization mass spectrometry.

PubMed

Ekdahl, Anja; Johansson, Maria C; Ahnoff, Martin

2013-04-01

Matrix effects on electrospray ionization were investigated for plasma samples analysed by hydrophilic interaction chromatography (HILIC) in gradient elution mode, and HILIC columns of different chemistries were tested for separation of plasma components and model analytes. By combining mass spectral data with post-column infusion traces, the following components of protein-precipitated plasma were identified and found to have significant effect on ionization: urea, creatinine, phosphocholine, lysophosphocholine, sphingomyelin, sodium ion, chloride ion, choline and proline betaine. The observed effect on ionization was both matrix-component and analyte dependent. The separation of identified plasma components and model analytes on eight columns was compared, using pair-wise linear correlation analysis and principal component analysis (PCA). Large changes in selectivity could be obtained by change of column, while smaller changes were seen when the mobile phase buffer was changed from ammonium formate pH 3.0 to ammonium acetate pH 4.5. While results from PCA and linear correlation analysis were largely in accord, linear correlation analysis was judged to be more straight-forward in terms of conduction and interpretation.

On N. Park's Analytical solution for steady state density- and mixing regime—dependent solute transport in a vertical soil column

NASA Astrophysics Data System (ADS)

Thiele, Michael

1998-04-01

Recently, Park [1996] presented an analytical solution for stationary one-dimensional solute transport in a variable-density fluid flow through a vertical soil column. He used the widespread Bear-Scheidegger dispersion model describing solute mixing as a sum of molecular diffusion and velocity-proportional mechanical dispersion effects. His closed-form implicit concentration and pressure distributions thus allow for a discussion of the combined impact of molecular diffusion and mechanical dispersion in a variable-density environment. Whereas Park only considered the example of vanishing molecular diffusion in detail, both phenomena are taken into account simultaneously in the present study in order to elucidate their different influences on concentration distribution characteristics. The boundary value problem dealt with herein is based on an upward inflow of high-density fluid of constant solute concentration and corresponding outflow of a lower constant concentration fluid at the upper end of the column when dispersivity does not change along the flow path. The thickness of the transition zone between the two fluids appeared to strongly depend on the prevailing share of the molecular diffusion and mechanical dispersion mechanisms. The latter can be characterized by a molecular Peclet number Pe, which here is defined as the ratio of the column outflow velocity multiplied by a characteristic pore size and the molecular diffusion coefficient. For very small values of Pe, when molecular diffusion represents the exclusive mixing process, density differences have no impact on transition zone thicknesses. A relative density-;dependent thickness increases with flow velocities (increasing Pe values) very rapidly compared to the density-independent case, and after having passed a maximum decreases asymptotically to a constant value for the large Peclet number limit when mechanical dispersion is the only mixing mechanism. Hence the special transport problem analyzed gives further evidence for the importance of simultaneously considering molecular diffusion and mechanical dispersion in gravity-affected solute transport in porous media.

THE PHASE COHERENCE OF INTERSTELLAR DENSITY FLUCTUATIONS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Burkhart, Blakesley; Lazarian, A.

2016-08-10

Studies of MHD turbulence often investigate the Fourier power spectrum to provide information on the nature of the turbulence cascade. However, the Fourier power spectrum only contains the Fourier amplitudes and rejects all information regarding the Fourier phases. Here, we investigate the utility of two statistical diagnostics for recovering information on Fourier phases in ISM column density maps: the averaged amplitudes of the bispectrum and the phase coherence index (PCI), a new phase technique for the ISM. We create three-dimensional density and two-dimensional column density maps using a set of simulations of isothermal ideal MHD turbulence with a wide rangemore » of sonic and Alfvénic Mach numbers. We find that the bispectrum averaged along different angles with respect to either the k {sub 1} or k {sub 2} axis is primarily sensitive to the sonic Mach number while averaging the bispectral amplitudes over different annuli is sensitive to both the sonic and Alfvénic Mach numbers. The PCI of density suggests that the most correlated phases occur in supersonic sub-Alfvénic turbulence and near the shock scale. This suggests that nonlinear interactions with correlated phases are strongest in shock-dominated regions, in agreement with findings from the solar wind. Our results suggest that the phase information contained in the bispectrum and PCI can be used to find the turbulence parameters in column density maps.« less

A Global Model of Meteoric Sodium

NASA Technical Reports Server (NTRS)

Marsh, Daniel R.; Janches, Diego; Feng, Wuhu; Plane, John M. C.

2013-01-01

A global model of sodium in the mesosphere and lower thermosphere has been developed within the framework of the National Center for Atmospheric Research's Whole Atmosphere Community Climate Model (WACCM). The standard fully interactive WACCM chemistry module has been augmented with a chemistry scheme that includes nine neutral and ionized sodium species. Meteoric ablation provides the source of sodium in the model and is represented as a combination of a meteoroid input function (MIF) and a parameterized ablation model. The MIF provides the seasonally and latitudinally varying meteoric flux which is modeled taking into consideration the astronomical origins of sporadic meteors and considers variations in particle entry angle, velocity, mass, and the differential ablation of the chemical constituents. WACCM simulations show large variations in the sodium constituents over time scales from days to months. Seasonality of sodium constituents is strongly affected by variations in the MIF and transport via the mean meridional wind. In particular, the summer to winter hemisphere flow leads to the highest sodium species concentrations and loss rates occurring over the winter pole. In the Northern Hemisphere, this winter maximum can be dramatically affected by stratospheric sudden warmings. Simulations of the January 2009 major warming event show that it caused a short-term decrease in the sodium column over the polar cap that was followed by a factor of 3 increase in the following weeks. Overall, the modeled distribution of atomic sodium in WACCM agrees well with both ground-based and satellite observations. Given the strong sensitivity of the sodium layer to dynamical motions, reproducing its variability provides a stringent test of global models and should help to constrain key atmospheric variables in this poorly sampled region of the atmosphere.

Chromatographic Separation, and Characteristics of Nucleic Acids from HeLa Cells

PubMed Central

Philipson, Lennart

1961-01-01

The application of the phenol-duponol method to extraction of nucleic acids from HeLa cells is described. Chromatography of the phenol extract on an esterified bovine serum albumin column with a salt gradient of sodium chloride gives separation of soluble RNA, DNA, and two different high molecular RNA fractions. Ultracentrifugation of the DNA eluted from the column gives a sedimentation coefficient (s 20 o,w) of 38, which agrees with ultracentrifugation data on the phenol extract. The eluted RNA appears polydisperse at low ionic strength, but at high ionic strength and after alcohol precipitation two fractions with the sedimentation coefficients of 16 and 25 to 29, respectively, were obtained. PMID:13735276

Comparison of the far-infrared and carbon monoxide emission in Heiles' Cloud 2 and B18

NASA Technical Reports Server (NTRS)

Snell, Ronald L.; Schloerb, F. Peter; Heyer, Mark H.

1989-01-01

A comparison is made of the far-IR emission detected by IRAS at 60 and 100 microns and the emission from C(-13)O in B18 and Heiles' Cloud 2. The results show that both these clouds have extended emission at the studied wavelengths and that this emission is correlated with the integrated intensity of (C-13)O emission. The dust temperature and optical depth, the gas column density, the mass of gas and dust, and the far-IR luminosity are derived and presented. The analysis shows that the dust optical depth is much better correlated with the gas column density than with the far-IR intensity. The dust temperature is found to be anticorrelated with the gas column density, suggesting that these clouds are externally heated by the interstellar radiation field. The far-IR luminosity-to-mass ratios for the clouds are substantially less than the average for the inner Galaxy.

Medium-resolution far-ultraviolet spectroscopy of PKS 2155-304

NASA Technical Reports Server (NTRS)

Appenzeller, I.; Mandel, H.; Krautter, J.; Bowyer, S.; Hurwitz, M.; Grewing, M.; Kramer, G.; Kappelmann, N.

1995-01-01

Using the Berkeley spectrometer of the Orbiting Retrievable Far and Extreme Ultraviolet Spectrometer (ORFEUS) we observed the 87-117 nm UV spectrum of the BL Lac object PKS 2155-304 with about 0.5 A resolution. In addition to the expected interstellar lines we detected higher quantum number counterparts of the intergalactic Lyman alpha lines discovered earlier with IUE and the Hubble Space Telescope (HST) in the direction of PKS 2155-304. The Lyman discontinuities indicate for three of the redshifted clouds a combined H I column density of 2-5 x 10(exp 16)/sq cm, while the column density for another cloud appears to be well below 5 x 10(exp 15)/sq cm. No siginificant O VI absorption in the galactic halo toward PKS 2155-304 could be detected from our data. Assuming that saturation effects are negligible for these weak features, we obtain for the O VI column density toward PKS 2155-304 a 3 sigma upper limit of 2.7 x 10(exp 14)/sq cm.

Biosorption of trivalent chromium by free and immobilized blue green algae: kinetics and equilibrium studies.

PubMed

Shashirekha, V; Sridharan, M R; Swamy, Mahadeswara

2008-03-01

The process of biosorption of trivalent chromium (Cr(3+)) by live culture of Spirulina platensis and the sorption potential by the dried biomass, in both free and immobilized states have been investigated for a simulated chrome liquor in the concentration range of 100-4500 ppm. Both live and dried biomass were very good biosorbents as they could remove high amounts of chromium from tannery wastewater. Polyurethane foam and sodium alginate were used as immobilizing agents and their performances compared. Biosorption kinetic data on Cr(3+) sorption onto dried biomass were analyzed using pseudo-first-and pseudo-second-order kinetic models in batch column experiments. The second-order equation was more appropriate to predict the rate of biosorption. Subsequently, the effects of height of packing & diameter of the column, concentration of blue-green algae (BGA) in varying amounts of sodium alginate, chromium concentration were studied. The results fit into both Langmuir & Freundlich isotherm models with very high regression coefficients. Furthermore, equilibrium studies using retan chrome liquor (RCL), with a chromium concentration of 1660 ppm, obtained from a tannery also showed promising results. In general, our studies indicate the efficacy of the algal species in removal of chromium from tannery wastewater.

High pressure-resistant nonincendive emulsion explosive

DOEpatents

Ruhe, Thomas C.; Rao, Pilaka P.

1994-01-01

An improved emulsion explosive composition including hollow microspheres/bulking agents having high density and high strength. The hollow microspheres/bulking agents have true particle densities of about 0.2 grams per cubic centimeter or greater and include glass, siliceous, ceramic and synthetic resin microspheres, expanded minerals, and mixtures thereof. The preferred weight percentage of hollow microspheres/bulking agents in the composition ranges from 3.0 to 10.0 A chlorinated paraffin oil, also present in the improved emulsion explosive composition, imparts a higher film strength to the oil phase in the emulsion. The emulsion is rendered nonincendive by the production of sodium chloride in situ via the decomposition of sodium nitrate, a chlorinated paraffin oil, and sodium perchlorate. The air-gap sensitivity is improved by the in situ formation of monomethylamine perchlorate from dissolved monomethylamine nitrate and sodium perchlorate. The emulsion explosive composition can withstand static pressures to 139 bars and dynamic pressure loads on the order of 567 bars.

Tire-derived carbon composite anodes for sodium-ion batteries

NASA Astrophysics Data System (ADS)

Li, Yunchao; Paranthaman, M. Parans; Akato, Kokouvi; Naskar, Amit K.; Levine, Alan M.; Lee, Richard J.; Kim, Sang-Ok; Zhang, Jinshui; Dai, Sheng; Manthiram, Arumugam

2016-06-01

Hard-carbon materials are considered as one of the most promising anodes for the emerging sodium-ion batteries. Here, we report a low-cost, scalable waste tire-derived carbon as an anode for sodium-ion batteries (SIBs). Tire-derived carbons obtained by pyrolyzing acid-treated tire at 1100 °C, 1400 °C and 1600 °C show capacities of 179, 185 and 203 mAh g-1, respectively, after 100 cycles at a current density of 20 mA g-1 in sodium-ion batteries with good electrochemical stability. The portion of the low-voltage plateau region in the charge-discharge curves increases as the heat-treatment temperature increases. The low-voltage plateau is beneficial to enhance the energy density of the full cell. This study provides a new pathway for inexpensive, environmentally benign and value-added waste tire-derived products towards large-scale energy storage applications.

Method of preparing silicon from sodium fluosilicate

DOEpatents

Schmidt, Frederick A.; Rehbein, David; Chiotti, Premo

1984-01-01

A process for preparing high purity silicon metal from Na.sub.2 SiF.sub.6 (sodium fluosilicate). The sodium fluosilicate is heated to decomposition temperature to form NaF, which retains most of the impurities, and gaseous SiF.sub.4. The SiF.sub.4 is then reduced by the bomb reduction method using a reductant having a low packing density.

Pseudocapacitive Sodium Storage in Mesoporous Single-Crystal-like TiO2-Graphene Nanocomposite Enables High-Performance Sodium-Ion Capacitors.

PubMed

Le, Zaiyuan; Liu, Fang; Nie, Ping; Li, Xinru; Liu, Xiaoyan; Bian, Zhenfeng; Chen, Gen; Wu, Hao Bin; Lu, Yunfeng

2017-03-28

Sodium-ion capacitors can potentially combine the virtues of high power capability of conventional electrochemical capacitors and high energy density of batteries. However, the lack of high-performance electrode materials has been the major challenge of sodium-based energy storage devices. In this work, we report a microwave-assisted synthesis of single-crystal-like anatase TiO 2 mesocages anchored on graphene as a sodium storage material. The architecture of the nanocomposite results in pseudocapacitive charge storage behavior with fast kinetics, high reversibility, and negligible degradation to the micro/nanostructure. The nanocomposite delivers a high capacity of 268 mAh g -1 at 0.2 C, which remains 126 mAh g -1 at 10 C for over 18 000 cycles. Coupling with a carbon-based cathode, a full cell of sodium-ion capacitor successfully demonstrates a high energy density of 64.2 Wh kg -1 at 56.3 W kg -1 and 25.8 Wh kg -1 at 1357 W kg -1 , as well as an ultralong lifespan of 10 000 cycles with over 90% of capacity retention.

The O VI Mystery: Mismatch between X-Ray and UV Column Densities

NASA Astrophysics Data System (ADS)

Mathur, S.; Nicastro, F.; Gupta, A.; Krongold, Y.; McLaughlin, B. M.; Brickhouse, N.; Pradhan, A.

2017-12-01

The UV spectra of Galactic and extragalactic sightlines often show O VI absorption lines at a range of redshifts, and from a variety of sources from the Galactic circumgalactic medium to active galactic nuclei (AGN) outflows. Inner shell O VI absorption is also observed in X-ray spectra (at λ =22.03 Å), but the column density inferred from the X-ray line was consistently larger than that from the UV line. Here we present a solution to this discrepancy for the z = 0 systems. The O II Kβ line {}4{S}0\\to {(}3D)3{p}4P at 562.40 eV (≡22.04 Å) is blended with the O VI Kα line in X-ray spectra. We estimate the strength of this O II line in two different ways, and show that in most cases the O II line accounts for the entire blended line. The small amount of O VI equivalent width present in some cases has column density entirely consistent with the UV value. This solution to the O VI discrepancy, however, does not apply to high column-density systems like AGN outflows. We discuss other possible causes to explain their UV/X-ray mismatch. The O VI and O II lines will be resolved by gratings on board the proposed mission Arcus and the concept mission Lynx, and would allow the detection of weak O VI lines not just at z = 0, but also at higher redshift.

Deuterium and Oxygen Toward Feige 110: Results from the Far Ultraviolet Spectroscopic Explorer (FUSE) Mission

NASA Technical Reports Server (NTRS)

Friedman, S. D.; Howk, J. C.; Chayer, P.; Tripp, T. M.; Hebrard, G.; Andre, M.; Oliveira, C.; Jenkins, E. B.; Moos, H. W.; Oegerle, William R.

2001-01-01

We present measurements of the column densities of interstellar D I and O I made with the Far Ultraviolet Spectroscopic Explorer (FUSE), and of H I made with the International Ultraviolet Explorer (IUE) toward the sdOB star Feige 110 [(l,b) = (74.09 deg., - 59.07 deg.); d = 179(sup +265, sub -67) pc; Z = -154(sup +57, Sub -227 pc). Our determination of the D I column density made use of curve of growth fitting and profile fitting analyses, while our O I column density determination used only curve of growth techniques. The H I column density was estimated by fitting the damping wings of the interstellar Ly(lpha) profile. We find log N(D I) = 15.47 +/- 0.06, log N(O I) = 16.73 +/- 0.10, and log N(H I) = 20.14(sup +0.13, sub -0.20) (all errors 2(sigma)). This implies D/H = (2.14 +/- 0.82) x 10(esp -5), D/O = (5.50(sup + 1.64, sub -133)) x 10(exp -2), and O/H = (3.89 +/- 1.67) x 10(exp -4). Taken with the FUSE results reported in companion papers and previous measurements of the local interstellar medium, this suggests the possibility of spatial variability in D/H for sight lines exceeding approx. 100 pc. This result may constrain models which characterize the mixing time and length scales of material in the local interstellar medium.

[Sensitive and selective HPLC methods with prechromatographic derivatization for the determination of cyclamate in foods].

PubMed

Rüter, J; Raczek, D I

1992-06-01

A sensitive and selective high pressure liquid chromatography (HPLC) procedure for the determination of sodium cyclamate in juices and preserves is presented. The method depends on the oxidation of cyclamate to cyclohexylamine, which then is converted prechromatographically into a fluorescent derivative. It is analyzed by HPLC on a C18:reversed-phase column and determined with fluorescence detection (excitation at 350 nm, emission at 440-650 nm). The detection limit of sodium cyclamate was 0.5-5 mg/kg, depending on the nature and dilution of the samples. The relative standard deviations thus obtained were +/- 1.0 to +/- 2.6%. The average recovery was 90%.

Testing Metal Chlorides For Use In Sodium-Cell Cathodes

NASA Technical Reports Server (NTRS)

Bugga, Ratnakumar V.; Attia, Alan I.; Halpert, Gerald

1992-01-01

Cyclic voltammetric curves of transition-metal wires in molten NaAlCl4 electrolyte used to eliminate suitability of transition metals as cathodes in sodium cells. Cyclic voltammetry used in conjunction with measurement of galvanostatic polarization curves determines whether given metal chloride suitable as cathode material in such cell. Cells useful in such high-energy-density and high-power-density applications as leveling loads on electric-power plants, supplying power to electric ground vehicles, and aerospace applications.

Inversion and Application of Muon Tomography Data for Cave Exploration in Budapest, Hungary

NASA Astrophysics Data System (ADS)

Molnár, Gábor; Surányi, Gergely; Gábor Barnaföldi, Gergely; Oláh, László; Hamar, Gergö; Varga, Dezsö

2016-04-01

In this contribution we present a prospecting muon-tomograph and its application for cave exploration in Budapest, Hungary. The more than 50 years old basic idea behind muon tomography is the ability of muon particles, generated in the upper atmosphere to penetrate tens of meters into rocks with continuous attenuation before decay. This enables us placing a detector in a tunnel and measure muon fluxes from different directions and convert these fluxes to rock density data. The lightweight, 51x46x32 cm3 size, muon tomograph containing 5 detector layers was developed by Wigner Research Centre for Physics, Budapest, Hungary. A muon passing at least 4 of the 5 detector layers along one line are classified as unique muon detection. Its angular resolution is approximately 1 degree and it is effective up to 50 degrees off zenith. During the measurement campaign we installed the muon detector at seventeen locations along an abandoned, likely Cold War air raid shelter tunnel for 10-15 days at each location, collecting large set of events. The measured fluxes are converted to apparent density lengths (multiplication of rock densities by along path lengths) using an empirically tested relationship. For inverting measurements, a 3D block model of the subsurface was developed. It consisted of cuboids, with equal horizontal size, equal number in every line and in every row of the model. Additionally it consisted of blocks with different heights, equal number of blocks in every column. (Block height was constant in a column, but varied from column to column.) The heights of the blocks in a column were chosen, that top face of the uppermost blocks has an elevation defined by a Digital Elevation Model. Initially the density of every model blocks was set to a realistic value. We calculated the theoretical density length for every detector location and for a subset of flux measurement directions. We also calculated the partial derivatives of these theoretical density length values with respect to the densities of every model block. This is the Jacobian of the problem and these values were proportional to the path length in the respective block. A regularized least squares solution returns the corrections of the densities of the blocks. If the corrected density of a block is significantly smaller than the typical rock density of the subsurface, the block is dedicated as a cave. According to our results a supposed cave exists some 7 meters above the tunnel. This work has been supported by the Lendület Program of the Hungarian Academy of Sciences (LP2013-60) and the OTKA NK-106119 grant. Gergely Gábor Barnaföld and Dezsö Varga thank for the support of the Bolyai Fellowship of the Hungarian Academy of Sciences.

The Arizona Radio Observatory CO Mapping Survey of Galactic Molecular Clouds. V. The Sh2-235 Cloud in CO J=2-1, 13CO J=2-1, and CO J=3-2

NASA Astrophysics Data System (ADS)

Bieging, John H.; Patel, Saahil; Peters, William L.; Toth, L. Viktor; Marton, Gábor; Zahorecz, Sarolta

2016-09-01

We present the results of a program to map the Sh2-235 molecular cloud complex in the CO and 13CO J = 2 - 1 transitions using the Heinrich Hertz Submillimeter Telescope. The map resolution is 38″ (FWHM), with an rms noise of 0.12 K brightness temperature, for a velocity resolution of 0.34 km s-1. With the same telescope, we also mapped the CO J = 3 - 2 line at a frequency of 345 GHz, using a 64 beam focal plane array of heterodyne mixers, achieving a typical rms noise of 0.5 K brightness temperature with a velocity resolution of 0.23 km s-1. The three spectral line data cubes are available for download. Much of the cloud appears to be slightly sub-thermally excited in the J = 3 level, except for in the vicinity of the warmest and highest column density areas, which are currently forming stars. Using the CO and 13CO J = 2 - 1 lines, we employ an LTE model to derive the gas column density over the entire mapped region. Examining a 125 pc2 region centered on the most active star formation in the vicinity of Sh2-235, we find that the young stellar object surface density scales as approximately the 1.6-power of the gas column density. The area distribution function of the gas is a steeply declining exponential function of gas column density. Comparison of the morphology of ionized and molecular gas suggests that the cloud is being substantially disrupted by expansion of the H II regions, which may be triggering current star formation.

Evaluation of separation properties of a modified strong cation exchange material named MEX and its application in 2D-MEX × C18 system to separate peptides from scorpion venom.

PubMed

Chen, Bo; Xu, Junyan; Fu, Qing; Dong, Xuefang; Guo, Zhimou; Jin, Yu; Liang, Xinmiao

2015-07-07

Peptides from scorpion venom represent one of the most promising drug sources for drug discovery for some specific diseases. Current challenges in their separation include high complexity, high homologies and the huge range of peptides. In this paper, a modified strong cation exchange material, named MEX, was utilised for the two-dimensional separation of peptides from complex scorpion venom. The silica-based MEX column was bonded with two functional groups; benzenesulfonic acid and cyanopropyl. To better understand its separation mechanisms, seven standard peptides with different properties were employed in an evaluation study, the results of which showed that two interactions were involved in the MEX column: electrostatic interactions based on benzenesulfonic acid groups dominated the separation of peptides; weak hydrophobic interactions introduced by cyanopropyl groups increased the column's selectivity for peptides with the same charge. This characteristic allowed the MEX column to overcome some of the drawbacks of traditional strong cation exchange (SCX) columns. Furthermore, the study showed the great effects of the acetonitrile (ACN) content, the sodium perchlorate (NaClO4) concentration and the buffer pH in the mobile phase on the peptides' retention and separation selectivity on the MEX column. Subsequently, the MEX column was combined with a C18 column to establish an off-line 2D-MEX × C18 system to separate peptides from scorpion Buthus martensi Karsch (BmK) venom. Due to complementary separation mechanisms in each dimension, a high orthogonality of 47.62% was achieved. Moreover, a good loading capacity, excellent stability and repeatability were exhibited by the MEX column, which are beneficial for its use in future preparation experiments. Therefore, the MEX column could be an alternative to the traditional SCX columns for the separation of peptides from scorpion venom.

Organic monolith frits encased in polyether ether ketone tubing with improved durability for liquid chromatography.

PubMed

Park, Sin Young; Cheong, Won Jo

2015-09-01

This study introduces a preparation method for polymer-encased monolith frits with improved durability for liquid chromatography columns. The inner surface of the polyether ether ketone tubing is pretreated with sulfuric acid in the presence of catalysts (vanadium oxide and sodium sulfate). The tubing was rinsed with water and acetone, flushed with nitrogen, and treated with glycidyl methacrylate. After washing, the monolith reaction mixture composed of lauryl methacrylate, ethylene glycol dimethacrylate, initiator, and porogenic solvent was filled in the tubing and subjected to in situ polymerization. The tubing was cut into thin slices and used as frits for microcolumns. To check their durability, the frit slices were placed in a vial and a heavy impact was applied on the vial by a vortex mixer for various periods. The frits made in the presence of catalysts were found to be more durable than those made without catalysts. Furthermore, when the monolith-incorporated tubing was used as a chromatography column, the column prepared in the presence of catalysts resulted in a better separation efficiency. The separation performance of the columns installed with the polyether ether ketone encased monolith frits was comparable to that of the columns installed with the commercial stainless-steel screen frits. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Chemical equilibria model of strontium-90 adsorption and transport in soil in response to dynamic alkaline conditions.

PubMed

Spalding, B P; Spalding, I R

2001-01-15

Strontium-90 is a major hazardous contaminant of radioactive wastewater and its processing sludges at many Department of Energy (DOE) facilities. In the past, such contaminated wastewater and sludge have been disposed in soil seepage pits, lagoons, or cribs often under highly perturbed alkaline conditions (pH > 12) where 90Sr solubility is low and its adsorption to surrounding soil is high. As natural weathering returns these soils to near-neutral or slightly acidic conditions, the adsorbed and precipitated calcium and magnesium phases, in which 90Sr is carried, change significantly in both nature and amounts. No comprehensive computational method has been formulated previously to quantitatively simulate the dynamics of 90Sr in the soil-groundwater environment under such dynamic and wide-ranging conditions. A computational code, the Hydrologic Utility Model for Demonstrating Integrated Nuclear Geochemical Environmental Responses (HUMDINGER), was composed to describe the changing equilibria of 90Sr in soil based on its causative chemical reactions including soil buffering, pH-dependent cation-exchange capacity, cation selectivity, and the precipitation/dissolution of calcium carbonate, calcium hydroxide, and magnesium hydroxide in response to leaching groundwater characteristics including pH, acid-neutralizing capacity, dissolved cations, and inorganic carbonate species. The code includes a simulation of one-dimensional transport of 90Sr through a soil column as a series of soil mixing cells where the equilibrium soluble output from one cell is applied to the next cell. Unamended soil leaching and highly alkaline soil treatments, including potassium hydroxide, sodium silicate, and sodium aluminate, were simulated and compared with experimental findings using large (10 kg) soil columns that were leached with 90Sr-contaminated groundwater after treatment. HUMDINGER's simulations were in good agreement with dynamic experimental observations of soil exchange capacity, exchangeable cations, total 90Sr, and pH values of layers within the soil columns and of column effluents.

Sodium-Doped Mesoporous Ni2P2O7 Hexagonal Tablets for High-Performance Flexible All-Solid-State Hybrid Supercapacitors.

PubMed

Wei, Chengzhen; Cheng, Cheng; Wang, Shanshan; Xu, Yazhou; Wang, Jindi; Pang, Huan

2015-08-01

A simple hydrothermal method has been developed to prepare hexagonal tablet precursors, which are then transformed into porous sodium-doped Ni2P2O7 hexagonal tablets by a simple calcination method. The obtained samples were evaluated as electrode materials for supercapacitors. Electrochemical measurements show that the electrode based on the porous sodium-doped Ni2P2O7 hexagonal tablets exhibits a specific capacitance of 557.7 F g(-1) at a current density of 1.2 A g(-1) . Furthermore, the porous sodium-doped Ni2P2O7 hexagonal tablets were successfully used to construct flexible solid-state hybrid supercapacitors. The device is highly flexible and achieves a maximum energy density of 23.4 Wh kg(-1) and a good cycling stability after 5000 cycles, which confirms that the porous sodium-doped Ni2P2 O7 hexagonal tablets are promising active materials for flexible supercapacitors. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

SEPARATION OF OCTYLPHENOL POLYETHER ALCOHOLS SURFACTANTS BY CAPILLARY COLUMN AND HPLC

EPA Science Inventory

Separation of nonionic octylphenol polyether alcohols (OPA) by supercritical fluid chromatography (SFC) and HPLC is described. sing a density programming and a 50-pm i.d. capillary column, a total of 18 group oligomers was separated. he effects of the operating parameters, such a...

X-Ray Wind Tomography of IGR J17252-3616

NASA Astrophysics Data System (ADS)

Manousakis, Antonios; Walter, Roland

2010-07-01

IGR J17252-3616, a highly absorbed High Mass X-ray Binary (HMXB) with Hydrogen column density NH~(2-4)×1023 cm-2, has been observed with XMM-Newton for about one month. Observations were scheduled in order to cover the orbital-phase space as much as possible. IGR J17252-3616 shows a varying column density NH and Fe Kα line when fit with simple phenomenological models. A refined orbital solution can be derived. Spectral timing analysis allows derivation of the wind properties of the massive star.

Influence of pressure on acoustic and rheologic parameters in water solutions of laury sodium sulfate

NASA Astrophysics Data System (ADS)

Khamidov, B. T.; Lezhnev, N. B.

1995-10-01

Ultrasonic velocity and density in water solutions of lauril sodium sulphate at frequency 36 MHz, within the range of pressures from 0.1 to 105 MPa at temperature T equals 293 K were measured. According to data of ultrasonic velocity and density under high pressures there was calculated adiabatic compressibility in objects studied from pressure. It was found out that the region of critical concentration of micelle formation has been shifted to the zone of much more low concentrations.

The behaviour of water and sodium chloride solution confined into asbestos nanotube

NASA Astrophysics Data System (ADS)

Fomin, Yu. D.; Ryzhov, V. N.; Tsiok, E. N.

2016-08-01

We present the molecular simulation study of the behaviour of water and sodium chloride solution confined in lizardite asbestos nanotube which is a typical example of hydrophilic confinement. The local structure and orientational and dynamic properties are studied. It is shown that at low enough temperatures there is a well-defined orientational ordering of the water molecules. At high local densities corresponding to the maxima of the density distribution function, the water molecules are oriented parallel to the axis of the tube. It is also shown that the diffusion coefficient drops about two orders of magnitude comparing to the bulk case. The behaviour of sodium chloride solutions is also considered and the formation of double layer is observed.

Methods of analysis by the U.S. Geological Survey National Water Quality Laboratory : determination of organophosphate pesticides in bottom sediment by gas chromatography with flame photometric detection

USGS Publications Warehouse

Jha, Virendra Kumar; Wydoski, Duane S.

2003-01-01

A method for the isolation of 20 parent organophosphate pesticides and 5 pesticide degradates from bottom-sediment samples is described. The compound O-ethyl-O-methyl-S-proplyphosphorothioate is reported as an estimated concentration because of variable performance. In this method, the sediment samples are centrifuged to remove excess waster mixed with anhydrous sodium sulfate and Soxhlet extracted overnight with dichloromethane (93 percent) and methanol (7 percent). The extract is concentrated and then filtered through a 0.2-micrometer polytetrafluoroethylene membrane syringe filter. An aliquot of the sample extract is quantitatively injected onto two polystyrene-divinylbenzene gel-permeation chromatographic columns connected in series. The compounds are eluted with dichloromethane and a fraction is collected for analysis, with some coextracted interferences, including elemental sulfur, separated and discarded. The aliquot is concentrated and solvent exchanged to ethyl acetate. The extract is analyzed by dual capillary-column gas chromatography with flame photometric detection. Single-operator method detection limits in sodium sulfate matrix samples ranged from 0.81 to 2 micrograms per kilogram. Method performance was validated by spiking all compounds into three different solid matrices (sodium sulfate, bed sediment from Clear Creek, and bed sediment from Evergreen Lake) at three different concentrations. Eight replicates were analyzed at each concentration in each matrix. Mean recoveries of method compounds spiked in Clear Creek samples ranged from 43 to 110 percent, and those in Evergreen Lake samples ranged from 62 to 118 percent for all pesticides. Mean recoveries of method compounds spiked in reagent sodium sulfate samples ranged from 41 to 101 percent for all pesticides. The only exception was O-ethyl-O-methyl-S-propylphosphorothioate, which had an average recovery of 35 percent, and, thus, sample concentration is reported as estimated ('E' remark code).

An Atlas of Computed Equivalent Widths of Quasar Broad Emission Lines

NASA Astrophysics Data System (ADS)

Korista, Kirk; Baldwin, Jack; Ferland, Gary; Verner, Dima

We present graphically the results of several thousand photoionization calculations of broad emission-line clouds in quasars, spanning 7 orders of magnitude in hydrogen ionizing flux and particle density. The equivalent widths of 42 quasar emission lines are presented as contours in the particle density-ionizing flux plane for a typical incident continuum shape, solar chemical abundances, and cloud column density of N(H) = 1023 cm-2. Results are similarly given for a small subset of emission lines for two other column densities (1022 and 1024 cm-2), five other incident continuum shapes, and a gas metallicity of 5 Z⊙. These graphs should prove useful in the analysis of quasar emission-line data and in the detailed modeling of quasar broad emission-line regions. The digital results of these emission-line grids and many more are available over the Internet.

Effects of solvent density on retention in gas-liquid chromatography. I. Alkanes solutes in polyethylene glycol stationary phases.

PubMed

González, F R; Pérez-Parajón, J; García-Domínguez, J A

2002-04-12

Gas-liquid chromatographic columns were prepared coating silica capillaries with poly(oxyethylene) polymers of different molecular mass distributions, in the range of low number-average molar masses, where the density still varies significantly. A novel, high-temperature, rapid evaporation method was developed and applied to the static coating of the low-molecular-mass stationary phases. The analysis of alkanes retention data from these columns reveals that the dependence of the partition coefficient with the solvent macroscopic density is mainly due to a variation of entropy. Enthalpies of solute transfer contribute poorly to the observed variations of retention. Since the alkanes solubility diminishes with the increasing solvent density, and this variation is weakly dependent with temperature, it is concluded that the decrease of free-volume in the liquid is responsible for this behavior.

Desorption and Bioavailability of PAHs in Contaminated Soil Subjected to Long-Term In Situ Biostimulation

PubMed Central

Richardson, Stephen D.; Aitken, Michael D.

2011-01-01

The distribution and potential bioavailability of polycyclic aromatic hydrocarbons (PAHs) in soil from a former manufactured-gas plant (MGP) site were examined before and after long-term biostimulation under simulated in situ conditions. Treated soil was collected from the oxygenated zones of two continuous-flow columns, one subjected to biostimulation and the other serving as a control, and separated into low- and high-density fractions. In the original soil, over 50% of the total PAH mass was associated with lower-density particles, which comprised < 2% of the total soil mass. However, desorbable fractions of PAHs were much lower in the low-density material than in the high-density material. After over 500 d of biostimulation, significant removal of total PAHs occurred in both the high- and low-density materials (77% and 53%, respectively), with three- and four-ring PAHs accounting for the majority of the observed mass loss. Total PAHs that desorbed over a 28-d period were substantially lower in treated soil from the biostimulated column than in the original soil for both the high-density material (23 versus 63%) and low-density material (5 versus 20%). The fast-desorbing fractions quantified by a two-site desorption model ranged from 0.1 to 0.5 for most PAHs in the original soil but were essentially zero in the biostimulated soil. The fast-desorbing fractions in the original soil underestimated the extent of PAH biodegradation observed in the biostimulated column, and thus was not a good predictor of PAH bioavailability after long-term, simulated in situ biostimulation. PMID:21932296

STAR FORMATION IN TURBULENT MOLECULAR CLOUDS WITH COLLIDING FLOW

DOE Office of Scientific and Technical Information (OSTI.GOV)

Matsumoto, Tomoaki; Dobashi, Kazuhito; Shimoikura, Tomomi, E-mail: matsu@hosei.ac.jp

2015-03-10

Using self-gravitational hydrodynamical numerical simulations, we investigated the evolution of high-density turbulent molecular clouds swept by a colliding flow. The interaction of shock waves due to turbulence produces networks of thin filamentary clouds with a sub-parsec width. The colliding flow accumulates the filamentary clouds into a sheet cloud and promotes active star formation for initially high-density clouds. Clouds with a colliding flow exhibit a finer filamentary network than clouds without a colliding flow. The probability distribution functions (PDFs) for the density and column density can be fitted by lognormal functions for clouds without colliding flow. When the initial turbulence ismore » weak, the column density PDF has a power-law wing at high column densities. The colliding flow considerably deforms the PDF, such that the PDF exhibits a double peak. The stellar mass distributions reproduced here are consistent with the classical initial mass function with a power-law index of –1.35 when the initial clouds have a high density. The distribution of stellar velocities agrees with the gas velocity distribution, which can be fitted by Gaussian functions for clouds without colliding flow. For clouds with colliding flow, the velocity dispersion of gas tends to be larger than the stellar velocity dispersion. The signatures of colliding flows and turbulence appear in channel maps reconstructed from the simulation data. Clouds without colliding flow exhibit a cloud-scale velocity shear due to the turbulence. In contrast, clouds with colliding flow show a prominent anti-correlated distribution of thin filaments between the different velocity channels, suggesting collisions between the filamentary clouds.« less

The presence of sodium nitrate in generator eluate decreases the radiochemical purity of 99mTc-sestamibi.

PubMed

Métayé, Thierry; Rosenberg, Thierry; Guilhot, Joëlle; Bouin-Pineau, Marie-Hélène; Perdrisot, Rémy

2012-09-01

A high radiochemical purity (RCP) is recommended for radiopharmaceutical compounds used in the clinical practice of nuclear medicine. However, some preparations of (99m)Tc-sestamibi contain excess impurities (>6%). To understand the origin of these impurities, we investigated the effect of sodium nitrate on the RCP of sestamibi preparations by testing eluates from 3 commercially available (99m)Tc generators. The sestamibi kits (Stamicis) were reconstituted with (99m)Tc eluate from nitrate-containing wet-column (NCWC), nitrate-free wet-column (NFWC), and nitrate-free dry-column (NFDC) generators. Sodium nitrate was 0.05 mg/mL in eluates from the NCWC generators. The RCP was determined using aluminum oxide sheets as the stationary phase and absolute ethanol as the mobile phase. Succimer, tetrofosmin, oxidronate, exametazine, albumin nanocolloid, and soluble albumin were also tested for their RCP values with eluates from the 3 different (99m)Tc generators. The RCP assessment of (99m)Tc-sestamibi was performed on 127 Stamicis preparations. Significantly lower RCP values were found for Stamicis kits prepared with the NCWC generator than for Stamicis prepared with the NFWC (P < 0.0001) and NFDC (P < 0.0001) generators. The number of Stamicis preparations with an RCP under 94% was greater with the NCWC generator (32 of 53 kits) than with the NFDC (2 of 51 kits) or NFWC (0 of 23 kits) generator. Furthermore, the addition of a 0.05 mg/mL concentration of nitrate in NFWC generator eluates significantly decreased the RCP of the Stamicis preparation. In the absence of nitrate in (99m)Tc eluate, no difference was observed between the RCP values of Stamicis kits prepared with the NFWC and NFDC generators. The (99m)Tc impurities generated by nitrates did not modify the quality of myocardial imaging (normal heart-to-lung ratio, 2.2), probably because these impurities are not in the heart field of view. No other tested (99m)Tc-radiopharmaceutical interfered with nitrates. We recommend using nitrate-free generator eluates in (99m)Tc-sestamibi preparations to improve the product quality and prevent unnecessary exposure of the patient to radiation.

Determination of free sulfites (SO3-2) in dried fruits processed with sulfur dioxide by ion chromatography through anion exchange column and conductivity detection.

PubMed

Liao, Benjamin S; Sram, Jacqueline C; Files, Darin J

2013-01-01

A simple and effective anion ion chromatography (IC) method with anion exchange column and conductivity detector has been developed to determine free sulfites (SO3-2) in dried fruits processed with sulfur dioxide. No oxidation agent, such as hydrogen peroxide, is used to convert sulfites to sulfates for IC analysis. In addition, no stabilizing agent, such as formaldehyde, fructose or EDTA, is required during the sample extraction. This method uses aqueous 0.2 N NaOH as the solvent for standard preparation and sample extraction. The sulfites, either prepared from standard sodium sulfite powder or extracted from food samples, are presumed to be unbound SO3-2 in aqueous 0.2 N NaOH (pH > 13), because the bound sulfites in the sample matrix are released at pH > 10. In this study, sulfites in the standard solutions were stable at room temperature (i.e., 15-25 degrees C) for up to 12 days. The lowest standard of the linear calibration curve is set at 1.59 microg/mL SO3-2 (equivalent to 6.36 microg/g sample with no dilution) for analysis of processed dried fruits that would contain high levels (>1000 microg/g) of sulfites. As a consequence, this method typically requires significant dilution of the sample extract. Samples are prepared with a simple procedure of sample compositing, extraction with aqueous 0.2 N NaOH, centrifugation, dilution as needed, and filtration prior to IC. The sulfites in these sample extracts are stable at room temperature for up to 20 h. Using anion IC, the sulfites are eluted under isocratic conditions with 10 mM aqueous sodium carbonate solution as the mobile phase passing through an anion exchange column. The sulfites are easily separated, with an analysis run time of 18 min, regardless of the dried fruit matrix. Recoveries from samples spiked with sodium sulfites were demonstrated to be between 81 and 105% for five different fruit matrixes (apricot, golden grape, white peach, fig, and mango). Overall, this method is simple to perform and effective for the determination of high levels of sulfites in dried fruits.

Evaluating the precision of passive sampling methods using PRCs in the water column.

EPA Science Inventory

To assess these models, four different thicknesses of low-density polyethylene (LDPE) passive samplers were co-deployed for 28 days in the water column at three sites in New Bedford Harbor, MA, USA. Each sampler was pre-loaded with six PCB performance reference compounds (PRCs) t...

SEPARATION OF T-MAZ ETHOXYLATED SORBITAN FATTY ACID ESTERS BY SUPERCRITICAL FLUID CHROMATOGRAPHY

EPA Science Inventory

The application of supercritical fluid chromatography (SFC) to the analysis of T-MAZ ethoxylated sorbitan fatty acid esters is described. FC separation methods utilize a density programming technique and a 50 um I.D. capillary column. his work demonstrates that capillary column S...

SEPARATION OF OCTYLPHENOL POLYETHER ALCOHOLS SURFACTANTS BY CAPILLARY COLUMN SFC AND HPLC

EPA Science Inventory

Separation of nonionic octylphenol polyether alcohols (OPA) by supercritical fluid chromatography (SFC) and HPLC is described. Using a density programming and a 50-μm i.d. capillary column, a total of 18 group oligomers was separated. The effects of the operating parameters, such...

Structure and stability in TMC-1: Analysis of NH3 molecular line and Herschel continuum data

NASA Astrophysics Data System (ADS)

Fehér, O.; Tóth, L. V.; Ward-Thompson, D.; Kirk, J.; Kraus, A.; Pelkonen, V.-M.; Pintér, S.; Zahorecz, S.

2016-05-01

Aims: We examined the velocity, density, and temperature structure of Taurus molecular cloud-1 (TMC-1), a filamentary cloud in a nearby quiescent star forming area, to understand its morphology and evolution. Methods: We observed high signal-to-noise (S/N), high velocity resolution NH3(1,1), and (2, 2) emission on an extended map. By fitting multiple hyperfine-split line profiles to the NH3(1, 1) spectra, we derived the velocity distribution of the line components and calculated gas parameters on several positions. Herschel SPIRE far-infrared continuum observations were reduced and used to calculate the physical parameters of the Planck Galactic Cold Clumps (PGCCs) in the region, including the two in TMC-1. The morphology of TMC-1 was investigated with several types of clustering methods in the parameter space consisting of position, velocity, and column density. Results: Our Herschel-based column density map shows a main ridge with two local maxima and a separated peak to the south-west. The H2 column densities and dust colour temperatures are in the range of 0.5-3.3 × 1022 cm-2 and 10.5-12 K, respectively. The NH3 column densities and H2 volume densities are in the range of 2.8-14.2 × 1014 cm-2 and 0.4-2.8 × 104 cm-3. Kinetic temperatures are typically very low with a minimum of 9 K at the maximum NH3 and H2 column density region. The kinetic temperature maximum was found at the protostar IRAS 04381+2540 with a value of 13.7 K. The kinetic temperatures vary similarly to the colour temperatures in spite of the fact that densities are lower than the critical density for coupling between the gas and dust phase. The k-means clustering method separated four sub-filaments in TMC-1 with masses of 32.5, 19.6, 28.9, and 45.9 M⊙ and low turbulent velocity dispersion in the range of 0.13-0.2 km s-1. Conclusions: The main ridge of TMC-1 is composed of four sub-filaments that are close to gravitational equilibrium. We label these TMC-1F1 through F4. The sub-filaments TMC-1F1, TMC-1F2, and TMC-1F4 are very elongated, dense, and cold. TMC-1F3 is a little less elongated and somewhat warmer, and probably heated by the Class I protostar, IRAS 04381+2540, which is embedded in it. TMC-1F3 is approximately 0.1 pc behind TMC1-F1. Because of its structure, TMC-1 is a good target to test filament evolution scenarios.

Permeation of sumatriptan succinate across human skin using multiple types of self-dissolving microneedle arrays fabricated from sodium hyaluronate.

PubMed

Wu, Dan; Katsumi, Hidemasa; Quan, Ying-Shu; Kamiyama, Fumio; Kusamori, Kosuke; Sakane, Toshiyasu; Yamamoto, Akira

2016-09-01

Available formulations of sumatriptan succinate (SS) have low bioavailability or are associated with site reactions. We developed various types of self-dissolving microneedle arrays (MNs) fabricated from sodium hyaluronate as a new delivery system for SS and evaluated their skin permeation and irritation in terms of clinical application. In vitro permeation studies with human skin, physicochemical properties (needle length, thickness and density), and penetration enhancers (glycerin, sodium dodecyl sulfate and lauric acid diethanolamide) were investigated. SS-loaded high-density MNs of 800 µm in length were the optimal formulation and met clinical therapeutic requirements. Penetration enhancers did not significantly affect permeation of SS from MNs. Optical coherence tomography images demonstrated that SS-loaded high-density MNs (800 µm) uniformly created drug permeation pathways for the delivery of SS into the skin. SS-loaded high-density MNs induced moderate primary skin irritations in rats, but the skin recovered within 72 h of removal of the MNs. These findings suggest that high-density MNs of 800 µm in length are an effective and promising formulation for transdermal delivery of SS. To our knowledge, this is the first report of SS permeation across human skin using self-dissolving MNs.

Pre-sodiated nickel cobaltite for high-performance sodium-ion capacitors

NASA Astrophysics Data System (ADS)

Yang, Dongfang; Sun, Xiaoming; Lim, Kyungmi; Ranganathan Gaddam, Rohit; Ashok Kumar, Nanjundan; Kang, Kisuk; Zhao, Xiu Song

2017-09-01

Sodium-ion capacitors (NICs) are a hybrid energy storage system that store energy via both charge adsorption at the cathode/electrolyte interface and charge intercalation in the bulk of the anode, thereby possessing a higher energy density than supercapacitors and a higher power density than batteries. In this work, nickel cobaltite (NiCo2O4) hollow spheres with a chestnut shell morphology have been solvothermally synthesized and tested in a sodium half-cell. The NiCo2O4 material exhibits a reversible capacity of 313 mAh g-1 at 1 A g-1. Pre-sodiation of NiCo2O4 is found to significantly improve its energy density. A NIC fabricated with pre-sodiated NiCo2O4 as the anode and an activated carbon (AC) as the cathode delivers an energy density of 60 Wh kg-1 at the power density of 10,000 W kg-1. Ex-situ X-ray diffraction (XRD) and transmission electron microscopy (TEM) results reveal that NiCo2O4 is converted to metallic nickel and cobalt and Na2O phases during the pre-sodiation. The metallic nickel and cobalt phases are kinetically favourable for the electrolyte diffusion and electrochemical reactions, thus significantly improving the performance of the pre-sodiated NiCo2O4 electrode.

The Mass and Absorption Columns of Galactic Gaseous Halos

NASA Astrophysics Data System (ADS)

Qu, Zhijie; Bregman, Joel N.

2018-01-01

The gaseous halo surrounding the galaxy is a reservoir for the gas on the galaxy disk, supplying materials for the star formation. We developed a gaseous halo model connecting the galactic disk and the gaseous halo by assuming the star formation rate is equal to the radiative cooling rate. Besides the single-phase collisional gaseous halo, we also consider the photoionization effect and a time-independent cooling model that assumes the mass cooling rate is constant over all temperatures. The photoionization dominates the low mass galaxy and the outskirts of the massive galaxy due to the low-temperature or low-density nature. The multi-phase cooling model dominates the denser region within the cooling radius, where the efficient radiative cooling must be included. Applying these two improvements, our model can reproduce the most of observed high ionization state ions (i.e., O VI, O VII, Ne VIII and Mg X). Our models show that the O VI column density is almost a constant of around 10^14 cm^-2 over a wide stellar mass from M_\\star ~10^8 M_Sun to 10^11 M_Sun, which is constant with current observations. This model also implies the O VI is photoionized for the galaxy with a halo mass <~ 3 * 10^11 M_Sun, while for more massive galaxies, the O VI is from the cooling-down medium from higher temperature materials (collisional ionized). As higher ionization states, Mg X and Ne VIII are also consistent with observations with the column density of 10^13.5 - 10^14.0 cm^-2, however, the absorber-galaxy pair sample is few to constrain the connection with the galaxy. Based on our calculation, such a gaseous halo cannot close the census of baryonic materials in the galaxy, which shows the same tendency as the baryonic fraction function of the EAGLE simulation. Finally, our model predicts plateaus of the Ne VIII and the Mg X column densities above the sub-L^* galaxy, and the possibly detectable O VII and O VIII column densities for low-mass galaxies, which help to determine the required detection limit for the future observations and missions.

Detections of Long Carbon Chains CH_{3}CCCCH, C_{6}H, LINEAR-C_{6}H_{2} and C_{7}H in the Low-Mass Star Forming Region L1527

NASA Astrophysics Data System (ADS)

Araki, Mitsunori; Takano, Shuro; Sakai, Nami; Yamamoto, Satoshi; Oyama, Takahiro; Kuze, Nobuhiko; Tsukiyama, Koichi

2017-06-01

Carbon chains in the warm carbon chain chemistry (WCCC) region has been searched in the 42-44 GHz region by using Green Bank 100 m telescope. Long carbon chains C_{7}H, C_{6}H, CH_{3}CCCCH, and linear-C_{6}H_{2} and cyclic species C_{3}H and C_{3}H_{2}O have been detected in the low-mass star forming region L1527, performing the WCCC. C_{7}H was detected for the first time in molecular clouds. The column density of C_{7}H is derived to be 6.2 × 10^{10} cm^{-2} by using the detected J = 24.5-23.5 and 25.5-24.5 rotational lines. The ^{2}Π_{1/2} electronic state of C_{6}H, locating 21.6 K above the ^{2}Π_{3/2} electronic ground state, and the K_a = 0 line of the para species of linear-C_{6}H_{2} were also detected firstly in molecular clouds. The column densities of the ^{2}Π_{1/2} and ^{2}Π_{3/2} states of C_{6}H in L1527 were derived to be 1.6 × 10^{11} and 1.1 × 10^{12} cm^{-2}, respectively. The total column density of linear-C_{6}H_{2} is obtained to be 1.86 × 10^{11} cm^{-2}. While the abundance ratios of carbon chains in between L1527 and the starless dark cloud Taurus Molecular Cloud-1 Cyanopolyyne Peak (TMC-1 CP) have a trend of decrease by extension of carbon-chain length, column densities of CH_{3}CCCCH and C_{6}H are on the trend. However, the column densities of linear-C_{6}H_{2}, and C_{7}H are as abundant as those of TMC-1 CP in spite of long carbon chain, i.e., they are not on the trend. The abundances of linear-C_{6}H_{2} and C_{7}H show that L1527 is rich for long carbon chains as well as TMC-1 CP.

The absorption spectrum of the QSO PKS 2126-158 (z_em =3.27) at high resolution

NASA Astrophysics Data System (ADS)

D'Odorico, V.; Cristiani, S.; D'Odorico, S.; Fontana, A.; Giallongo, E.

1998-01-01

Spectra of the z_em = 3.268 quasar PKS 2126-158 have been obtained in the range lambda lambda 4300-6620 Angstroms with a resolution Rsmallimeq27000 and an average signal-to-noise ratio s/nsmallimeq 25 per resolution element. The list of the identified absorption lines is given together with their fitted column densities and Doppler widths. The modal value of the Doppler parameter distribution for the Lyalpha lines is smallimeq 25 km s(-1) . The column density distribution can be described by a power-law dn / dN ~ N(-beta ) with beta smallimeq 1.5. 12 metal systems have been identified, two of which were previously unknown. In order to make the column densities of the intervening systems compatible with realistic assumptions about the cloud sizes and the silicon to carbon overabundance, it is necessary to assume a jump beyond the He II edge in the spectrum of the UV ionizing background at z smallim 3 a factor 10 larger than the standard predictions for the integrated quasar contribution. An enlarged sample of C IV absorptions (71 doublets) has been used to analyze the statistical properties of this class of absorbers strictly related to galaxies. The column density distribution is well described by a single power-law, with beta =1.64 and the Doppler parameter distribution shows a modal value b_CIV smallimeq 14 km s(-1) . The two point correlation function has been computed in the velocity space for the individual components of C IV features. A significant signal is obtained for scales smaller than 200- 300 km s(-1) , xi (30< Delta v < 90 km\\ s(-1) ) = 33 +/- 3. A trend of decreasing clustering amplitude with decreasing column density is apparent, analogously to what has been observed for Lyalpha lines. Based on observations collected at the European Southern Observatory, La Silla, Chile (ESO No. 2-013-49K). Table 2 is only available in electronic from via anonymous ftp 130.79.128.5 or http://cdsweb.u-strasbg.fr/Abstract.html

First detection of hydrogen in the β Pictoris gas disk

NASA Astrophysics Data System (ADS)

Wilson, P. A.; Lecavelier des Etangs, A.; Vidal-Madjar, A.; Bourrier, V.; Hébrard, G.; Kiefer, F.; Beust, H.; Ferlet, R.; Lagrange, A.-M.

2017-03-01

The young and nearby star β Pictoris (β Pic) is surrounded by a debris disk composed of dust and gas known to host a myriad evaporating exocomets, planetesimals and at least one planet. At an edge-on inclination, as seen from Earth, this system is ideal for debris disk studies providing an excellent opportunity to use absorption spectroscopy to study the planet forming environment. Using the Cosmic Origins Spectrograph (COS) instrument on the Hubble Space Telescope (HST) we observe the most abundant element in the disk, hydrogen, through the H I Lyman α (Ly-α) line. We present a new technique to decrease the contamination of the Ly-α line by geocoronal airglow in COS spectra. This Airglow Virtual Motion (AVM) technique allows us to shift the Ly-α line of the astrophysical target away from the contaminating airglow emission revealing more of the astrophysical line profile. This new AVM technique, together with subtraction of an airglow emission map, allows us to analyse the shape of the β Pic Ly-α emission line profile and from it, calculate the column density of neutral hydrogen surrounding β Pic. The column density of hydrogen in the β Pic stable gas disk at the stellar radial velocity is measured to be log (NH/ 1 cm2) ≪ 18.5. The Ly-α emission line profile is found to be asymmetric and we propose that this is caused by H I falling in towards the star with a bulk radial velocity of 41 ± 6 km s-1 relative to β Pic and a column density of log (NH/ 1 cm2) = 18.6 ± 0.1. The high column density of hydrogen relative to the hydrogen content of CI chondrite meteorites indicates that the bulk of the hydrogen gas does not come from the dust in the disk. This column density reveals a hydrogen abundance much lower than solar, which excludes the possibility that the detected hydrogen could be a remnant of the protoplanetary disk or gas expelled by the star. We hypothesise that the hydrogen gas observed falling towards the star arises from the dissociation of water originating from evaporating exocomets.

An empirical model to estimate density of sodium hydroxide solution: An activator of geopolymer concretes

NASA Astrophysics Data System (ADS)

Rajamane, N. P.; Nataraja, M. C.; Jeyalakshmi, R.; Nithiyanantham, S.

2016-02-01

Geopolymer concrete is zero-Portland cement concrete containing alumino-silicate based inorganic polymer as binder. The polymer is obtained by chemical activation of alumina and silica bearing materials, blast furnace slag by highly alkaline solutions such as hydroxide and silicates of alkali metals. Sodium hydroxide solutions of different concentrations are commonly used in making GPC mixes. Often, it is seen that sodium hydroxide solution of very high concentration is diluted with water to obtain SHS of desired concentration. While doing so it was observed that the solute particles of NaOH in SHS tend to occupy lower volumes as the degree of dilution increases. This aspect is discussed in this paper. The observed phenomenon needs to be understood while formulating the GPC mixes since this influences considerably the relationship between concentration and density of SHS. This paper suggests an empirical formula to relate density of SHS directly to concentration expressed by w/w.

Kinetics of plasma formation in sodium vapor excited by nanosecond resonant laser pulses

NASA Astrophysics Data System (ADS)

Mahmoud, M. A.; Gamal, Y. E. E.

2012-07-01

We have studied theoretically formation of molecular ion Na2 + and the atomic ion Na+ which are created in laser excited sodium vapor at the first resonance transition, 3S1/2-3P1/2. A set of rate equations, which describe the temporal variation of the electron energy distribution function (EEDF), the electron density, the population density of the excited states as well as the atomic Na+ and molecular ion Na2 +, are solved numerically. The calculations are carried out at different laser energy and different sodium atomic vapor densities. The numerical calculations of the EEDF show that a deviation from the Maxwellian distribution due to the superelastic collisions effect. In addition to the competition between associative ionization (3P-3P), associative ionization (3P-3D) and Molnar-Hornbeck ionization processes for producing Na2 +, the calculations have also shown that the atomic ions Na+ are formed through the Penning ionization and photoionization processes. These results are found to be consistent with the experimental observations.

Internal waves interacting with particles in suspension

NASA Astrophysics Data System (ADS)

Micard, Diane

2016-04-01

Internal waves are produced as a consequence of the dynamic balance between buoy- ancy and gravity forces when a particle of fluid is vertically displaced in a stable stratified environment. Geophysical systems such as ocean and atmosphere are naturally stratified and therefore suitable for internal waves to propagate. Furthermore, these two environ- ments stock a vast amount of particles in suspension, which present a large spectrum of physical properties (size, density, shape), and can be organic, mineral or pollutant agents. Therefore, it is reasonable to expect that internal waves will have an active effect over the dynamics of these particles. In order to study the interaction of internal waves and suspended particles, an ide- alized experimental setup has been implemented. A linear stratification is produced in a 80×40×17 cm3 tank, in which two dimensional plane waves are created thanks to the inno- vative wave generator GOAL. In addition, a particle injector has been developed to produce a vertical column of particles within the fluid, displaying the same two-dimensional sym- metry as the waves. The particle injector allows to control the volumic fraction of particles and the size of the column. The presence of internal waves passing through the column of particles allowed to observe two main effects: The column oscillates around an equilibrium position (which is observed in both, the contours an the interior of the column), and the column is displaced as a whole. The column is displaced depending on the characteristics of the column, the gradient of the density, and the intensity and frequency of the wave. When displaced, the particles within the column are sucked towards the source of waves. The direction of the displacement of the column is explained by computing the effect of the Lagrangian drift generated by the wave over the time the particles stay in the wave beam before settling.

The Design and Development of a Regenerative Separatory Column Using Calixarenes as a Polymeric Backbone for the Purification of Water from Urine

NASA Technical Reports Server (NTRS)

Polk, M.

1999-01-01

The objective of this research project is to design calixarenes, cup-shaped molecules, with the specific binding sites to the sodium chloride and nitrogen containing components of urine, such as urea and uric acid, in urine. The following partition of the research accomplishes this objective: (1) functionalization of calixarene, (2) development of a calixarene based medium for the separatory process, (3) design of the column regeneration protocol. Work was also accomplished in the area of temperature sensitive paint (TSP). Research was undertaken to design a TSP with insulating propertites. An important part of this research project is to discover the thermal conductivity of polymers for TSP.

Galactic interstellar abundance surveys with IUE and IRAS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Van Steenberg, M.E.

1987-01-01

This thesis is a survey of interstellar densities, abundances, and cloud structure in the Galaxy, using two NASA satellites: the International Ultraviolet Explorer (IUE) and Infrared Astronomical Satellite (IRAS). From IUE high-resolution spectra, the author measured equivalent widths of 18 ultraviolet resonance transitions and derived column densities for Si/sup +/, Mn/sup +/, Fe/sup +/, S/sup +/, and Zn/sup +/ toward 261 early-type stars. From the IRAS all-sky survey he also measured the infrared cirrus flux. He examined the variations of the measured parameters with spectral type, E(B-V), galactic longitude and latitude, distance from the Sun, and mean density. The hydrogen-columnmore » densities, metal-column densities, and gas-to-dust ratio are in good agreement with Copernicus surveys. The derived interstellar abundances yield mean logarithmic depletions. These depletions correlate with mean density but not with the physical density derived from Copernicus H/sub 2/ rotational states. Abundance ratios indicate a larger Fe halo abundance compared to Si, Mn, S, or Zn, which may result from selective grain processing in shocks or from Type I supernovae.« less

Smooth H I Low Column Density Outskirts in Nearby Galaxies

NASA Astrophysics Data System (ADS)

Ianjamasimanana, R.; Walter, Fabian; de Blok, W. J. G.; Heald, George H.; Brinks, Elias

2018-06-01

The low column density gas at the outskirts of galaxies as traced by the 21 cm hydrogen line emission (H I) represents the interface between galaxies and the intergalactic medium, i.e., where galaxies are believed to get their supply of gas to fuel future episodes of star formation. Photoionization models predict a break in the radial profiles of H I at a column density of ∼5 × 1019 cm‑2 due to the lack of self-shielding against extragalactic ionizing photons. To investigate the prevalence of such breaks in galactic disks and to characterize what determines the potential edge of the H I disks, we study the azimuthally averaged H I column density profiles of 17 nearby galaxies from the H I Nearby Galaxy Survey and supplemented in two cases with published Hydrogen Accretion in LOcal GAlaxieS data. To detect potential faint H I emission that would otherwise be undetected using conventional moment map analysis, we line up individual profiles to the same reference velocity and average them azimuthally to derive stacked radial profiles. To do so, we use model velocity fields created from a simple extrapolation of the rotation curves to align the profiles in velocity at radii beyond the extent probed with the sensitivity of traditional integrated H I maps. With this method, we improve our sensitivity to outer-disk H I emission by up to an order of magnitude. Except for a few disturbed galaxies, none show evidence of a sudden change in the slope of the H I radial profiles: the alleged signature of ionization by the extragalactic background.

Survey Observations to Study Chemical Evolution from High-mass Starless Cores to High-mass Protostellar Objects. I. HC3N and HC5N

NASA Astrophysics Data System (ADS)

Taniguchi, Kotomi; Saito, Masao; Sridharan, T. K.; Minamidani, Tetsuhiro

2018-02-01

We carried out survey observations of HC3N and HC5N in the 42‑45 GHz band toward 17 high-mass starless cores (HMSCs) and 35 high-mass protostellar objects (HMPOs) with the Nobeyama 45 m radio telescope. We have detected HC3N from 15 HMSCs and 28 HMPOs, and HC5N from 5 HMSCs and 14 HMPOs, respectively. The average values of the column density of HC3N are found to be (5.7+/- 0.7) × {10}12 and (1.03+/- 0.12)×{10}13 cm‑2 in HMSCs and HMPOs, respectively. The average values of the fractional abundance of HC3N are derived to be (6.6+/- 0.8)× {10}-11 and (3.6+/- 0.5)× {10}-11 in HMSCs and HMPOs, respectively. We find that the fractional abundance of HC3N decreases from HMSCs to HMPOs using the Kolmogorov–Smirnov test. On the other hand, its average value of the column density slightly increases from HMSCs to HMPOs. This may imply that HC3N is newly formed in dense gas in HMPO regions. We also investigate the relationship between the column density of HC3N in HMPOs and the luminosity-to-mass ratio (L/M), a physical evolutional indicator. The column density of HC3N tends to decrease with the increase of the L/M ratio, which suggests that HC3N is destroyed by the stellar activities.

An X-Ray Spectral Model for Clumpy Tori in Active Galactic Nuclei

NASA Astrophysics Data System (ADS)

Liu, Yuan; Li, Xiaobo

2014-05-01

We construct an X-ray spectral model for the clumpy torus in an active galactic nucleus (AGN) using Geant4, which includes the physical processes of the photoelectric effect, Compton scattering, Rayleigh scattering, γ conversion, fluorescence line, and Auger process. Since the electrons in the torus are expected to be bounded instead of free, the deviation of the scattering cross section from the Klein-Nishina cross section has also been included, which changes the X-ray spectra by up to 25% below 10 keV. We have investigated the effect of the clumpiness parameters on the reflection spectra and the strength of the fluorescent line Fe Kα. The volume filling factor of the clouds in the clumpy torus only slightly influences the reflection spectra, however, the total column density and the number of clouds along the line of sight significantly change the shapes and amplitudes of the reflection spectra. The effect of column density is similar to the case of a smooth torus, while a small number of clouds along the line of sight will smooth out the anisotropy of the reflection spectra and the fluorescent line Fe Kα. The smoothing effect is mild in the low column density case (N H = 1023 cm-2), whereas it is much more evident in the high column density case (N H = 1025 cm-2). Our model provides a quantitative tool for the spectral analysis of the clumpy torus. We suggest that the joint fits of the broad band spectral energy distributions of AGNs (from X-ray to infrared) should better constrain the structure of the torus.

Gravity or turbulence? IV. Collapsing cores in out-of-virial disguise

NASA Astrophysics Data System (ADS)

Ballesteros-Paredes, Javier; Vázquez-Semadeni, Enrique; Palau, Aina; Klessen, Ralf S.

2018-06-01

We study the dynamical state of massive cores by using a simple analytical model, an observational sample, and numerical simulations of collapsing massive cores. From the analytical model, we find that cores increase their column density and velocity dispersion as they collapse, resulting in a time evolution path in the Larson velocity dispersion-size diagram from large sizes and small velocity dispersions to small sizes and large velocity dispersions, while they tend to equipartition between gravity and kinetic energy. From the observational sample, we find that: (a) cores with substantially different column densities in the sample do not follow a Larson-like linewidth-size relation. Instead, cores with higher column densities tend to be located in the upper-left corner of the Larson velocity dispersion σv, 3D-size R diagram, a result explained in the hierarchical and chaotic collapse scenario. (b) Cores appear to have overvirial values. Finally, our numerical simulations reproduce the behavior predicted by the analytical model and depicted in the observational sample: collapsing cores evolve towards larger velocity dispersions and smaller sizes as they collapse and increase their column density. More importantly, however, they exhibit overvirial states. This apparent excess is due to the assumption that the gravitational energy is given by the energy of an isolated homogeneous sphere. However, such excess disappears when the gravitational energy is correctly calculated from the actual spatial mass distribution. We conclude that the observed energy budget of cores is consistent with their non-thermal motions being driven by their self-gravity and in the process of dynamical collapse.

Probing the structure of the gas in the Milky Way through X-ray high-resolution spectroscopy

NASA Astrophysics Data System (ADS)

Gatuzz, Efraín; Churazov, Eugene

2018-02-01

We have developed a new X-ray absorption model, called IONeq, which computes the optical depth τ(E) simultaneously for ions of all abundant elements, assuming ionization equilibrium and taking into account turbulent broadening. We use this model to analyse the interstellar medium (ISM) absorption features in the Milky Way for a sample of 18 Galactic (LMXBs) and 42 extragalactic sources (mainly Blazars). The absorbing ISM was modelled as a combination of three components/phases - neutral (T ≲ 1 × 104 K), warm (T ˜ 5 × 104 K) and hot (T ˜ 2 × 106 K). We found that the spatial distribution of both, neutral and warm components, are difficult to describe using smooth profiles due to non-uniform distribution of the column densities over the sky. For the hot phase we used a combination of a flattened disc and a halo, finding comparable column densities for both spatial components, of the order of ˜6-7 × 1018 cm-2, although this conclusion depends on the adopted parametrization. If the halo component has sub-solar abundance Z, then the column density has to be scaled up by a factor of Z_{⊙}/Z. The vertically integrated column densities of the disc components suggest the following mass fractions for these three ISM phases in the Galactic disc: neutral ˜ 89 per cent, warm ˜ 8 per cent and hot ˜ 3 per cent components, respectively. The constraints on the radial distribution of the halo component of the hot component are weak.

Comparison between Procedures using Sodium Dodecyl Sulfate for Shotgun Proteomic Analyses of Complex Samples

PubMed Central

Bereman, Michael S.; Egertson, Jarrett D.; MacCoss, Michael J.

2012-01-01

Filter aided sample preparation (FASP) and a new sample preparation method using a modified commercial SDS removal spin column are quantitatively compared in terms of their performance for shotgun proteomic experiments in three complex proteomic samples: a Saccharomyces cerevisiae lysate (insoluble fraction), a Caenorhabditis elegans lysate (soluble fraction), and a human embryonic kidney cell line (HEK293T). The characteristics and total number of peptides and proteins identified are compared between the two procedures. The SDS spin column procedure affords a conservative 4-fold improvement in throughput, is more reproducible, less expensive (i.e., requires less materials), and identifies between 30–107% more peptides at a q≤0.01, than the FASP procedure. The peptides identified by SDS spin column are more hydrophobic than species identified by the FASP procedure as indicated by the distribution of GRAVY scores. Ultimately, these improvements correlate to as great as a 50% increase in protein identifications with 2 or more peptides. PMID:21656683

Post-column reaction for simultaneous analysis of chromatic and leuco forms of malachite green and crystal violet by high-performance liquid chromatography with photometric detection

USGS Publications Warehouse

Allen, J.L.; Meinertz, J.R.

1991-01-01

The chromatic and leuco forms of malachite green and crystal violet were readily separated and detected by a sensitive and selective high-performance liquid chromatographic procedure. The chromatic and leuco forms of the dyes were separated within 11 min on a C18 column with a mobile phase of 0.05 M sodium acetate and 0.05 M acetic acid in water (19%) and methanol (81%). A reaction chamber, containing 10% PbO2 in Celite 545, was placed between the column and the spectrophotometric detector to oxidize the leuco forms of the dyes to their chromatic forms. Chromatic and leuco malachite green were quantified by their absorbance at 618 nm; and chromatic and leuco Crystal Violet by their absorbance at 588 nm. Detection limits for chromatic and leuco forms of both dyes ranged from 0.12 to 0.28 ng. A linear range of 1 to 100 ng was established for both forms of the dyes.

A RELATION BETWEEN THE WARM NEUTRAL AND IONIZED MEDIA OBSERVED IN THE CANADIAN GALACTIC PLANE SURVEY

DOE Office of Scientific and Technical Information (OSTI.GOV)

Foster, T.; Kothes, R.; Brown, J. C., E-mail: Tyler.Foster@nrc-cnrc.gc.ca

2013-08-10

We report on a comparison between 21 cm rotation measure (RM) and the optically thin atomic hydrogen column density (N{sub H{sub I}}({tau} {yields} 0)) measured toward unresolved extragalactic sources in the Galactic plane of the northern sky. H I column densities integrated to the Galactic edge are measured immediately surrounding each of nearly 2000 sources in 1 arcmin 21 cm line data, and are compared to RMs observed from polarized emission of each source. RM data are binned in column density bins 4 Multiplication-Sign 10{sup 20} cm{sup -2} wide, and one observes a strong relationship between the number of hydrogenmore » atoms in a 1 cm{sup 2} column through the plane and the mean RM along the same line of sight and path length. The relationship is linear over one order of magnitude (from 0.8 to 14 Multiplication-Sign 10{sup 21} atoms cm{sup -2}) of column densities, with a constant RM/N{sub H{sub I}}{approx} -23.2 {+-} 2.3 rad m{sup -2}/10{sup 21} atoms cm{sup -2}, and a positive RM of 45.0 {+-} 13.8 rad m{sup -2} in the presence of no atomic hydrogen. This slope is used to calculate a mean volume-averaged magnetic field in the second quadrant of (B{sub Parallel-To }) {approx}1.0 {+-} 0.1 {mu}G directed away from the Sun, assuming an ionization fraction of 8% (consistent with the warm-neutral medium; WNM). The remarkable consistency between this field and (B) = 1.2 {mu}G found with the same RM sources and a Galactic model of dispersion measures (DMs) suggests that electrons in the partially ionized WNM are mainly responsible for pulsar DMs, and thus the partially ionized WNM is the dominant form of the magneto-ionic interstellar medium.« less

Quantitative measurements of vaporization, burst ionization, and emission characteristics of shaped charge barium releases

NASA Technical Reports Server (NTRS)

Hoch, Edward L.; Hallinan, Thomas J.; Stenbaek-Nielsen, Hans C.

1994-01-01

Intensity-calibrated color video recordings of three barium-shaped charge injections in the ionopshere were used to determine the initial ionization, the column density corresponding to unity optical depth, and the yield of vaporized barium in the fast jet. It was found that the initial ionization at the burst was less than 1% and that 0% burst ionization was consistent with the observations. Owing to the Doppler shift, the column density for optical thickness in the neutral barium varies somewhat according to the velocity distribution. For the cases examined here, the column density was 2-5 x 10(exp 10) atoms/sq cm. This value, which occurred 12 to 15 s after release, should be approximately valid for most shaped charge experiments. The yield was near 30% (15% in the fast jet) for two of the releases and was somewhat lower in the third, which also had a lower peak velocity. This study also demonstrated the applicability of the computer simulation code developed for chemical releases by Stenbaek-Nielsen and provided experimental verification of the Doppler-corrected emission rates calculated b Stenbaek-Nielsen (1989).

Analysis of interstellar cloud structure based on IRAS images

NASA Technical Reports Server (NTRS)

Scalo, John M.

1992-01-01

The goal of this project was to develop new tools for the analysis of the structure of densely sampled maps of interstellar star-forming regions. A particular emphasis was on the recognition and characterization of nested hierarchical structure and fractal irregularity, and their relation to the level of star formation activity. The panoramic IRAS images provided data with the required range in spatial scale, greater than a factor of 100, and in column density, greater than a factor of 50. In order to construct densely sampled column density maps of star-forming clouds, column density images of four nearby cloud complexes were constructed from IRAS data. The regions have various degrees of star formation activity, and most of them have probably not been affected much by the disruptive effects of young massive stars. The largest region, the Scorpius-Ophiuchus cloud complex, covers about 1000 square degrees (it was subdivided into a few smaller regions for analysis). Much of the work during the early part of the project focused on an 80 square degree region in the core of the Taurus complex, a well-studied region of low-mass star formation.

Combined extraction-cleanup column chromatographic procedure for determination of dicofol in avian eggs

USGS Publications Warehouse

Krynitsky, A.J.; Stafford, C.J.; Wiemeyer, Stanley N.

1988-01-01

Dicofol in avian eggs was completely oxidized to dichlorobenzophenone (DCBP) when a hexane Soxhlet extraction procedure was used. This degradation did not occur with other avian tissues (muscle and liver). For this reason, a combined extraction-cleanup column chromatographic procedure, without added heat, was developed for the determination of dicofol in avian eggs. Homogenized subsamples of eggs were mixed with sodium sulfate, and the mixture was added as the top layer on a column prepacked with Florisil. The dicofol and other compounds of interest were then eluted with ethyl ether-hexane. The extracts, relatively free from lipids, were quantitated on a gas chromatograph equipped with a 63Ni electron-capture detector and a methyl silicone capillary column. Recoveries from chicken eggs, fortified with dicofol and other DDT-related compounds, averaged 96%. Analysis of eggs of eastern screech-owls, fed a meat diet containing 10 ppm technical Kelthane, showed that both dicofol and DCBP were present. Results were confirmed by gas chromatography/mass spectrometry. This method is rapid and reliable, involves a minimum of sample handling, and is well suited for high volume determination of dicofol in eggs and other avian tissues.

Chiral recognition ability of an (S)-naproxen- imprinted monolith by capillary electrochromatography.

PubMed

Xu, Yan-Li; Liu, Zhao-Sheng; Wang, He-Fang; Yan, Chao; Gao, Ru-Yu

2005-02-01

The racemic naproxen was selectively recognized by capillary electrochromatography (CEC) on an (S)-naproxen-imprinted monolith, which was prepared by an in situ thermal-initiated polymerization. The recognition selectivity of a selected monolith strictly relied on the CEC conditions involved. The factors that influence the imprinting selectivity as well as the electroosmotic flow (EOF), including the applied voltage, organic solvent, salt concentration and pH value of the buffer, column temperature, and surfactant modifiers were systematically studied. Once the column was prepared, the experiment results showed that the successful chiral recognition was dependent on CEC variables. For example: the recognition could be observed in acetonitrile and ethanol electrolytes, while methanol and dimethyl sulfoxide (DMSO) electrolytes had no chiral recognition ability. The buffer with pH values of 2.6 or 3.0 at a higher salt concentration had chiral recognition ability. Column temperatures of 25-35 degrees C were optimal. Three surfactants, sodium dodecyl sulfate (SDS), cetyltrimethylammonium bromide (CTAB), and polyoxyethylene sorbitan monolaurate (Tween 20), can improve the recognition. Baseline resolution was obtained under optimized conditions and the column efficiency of the later eluent (S)-naproxen was 90 000 plates/m.

Deproteinizing methods evaluated for determination of uric acid in serum by reversed-phase liquid chromatography with ultraviolet detection.

PubMed

Sakuma, R; Nishina, T; Kitamura, M

1987-08-01

We evaluated six deproteinizing methods for determination of uric acid in serum by "high-performance" liquid chromatography with ultraviolet detection: those involving zinc hydroxide, sodium tungstate, trichloroacetic acid, perchloric acid, acetonitrile, and centrifugal ultrafiltration (with Amicon MPS-1 devices). We used a Toyosoda ODS-120A reversed-phase column. The mobile phase was sodium phosphate buffer (40 mmol/L, pH 2.2) containing 20 mL of methanol per liter. Absorbance of the eluate was monitored at 284 nm. The precipitation method with perchloric acid gave high recoveries of uric acid and good precision, and results agreed with those by the uricase-catalase method of Kageyama (Clin Chim Acta 1971;31:421-6).

[Dependence of ion transport across the plasma membrane on cell culture density. II. Active and passive cation transport during the growth of L cell cultures].

PubMed

Marakhova, I I; Sal'nikov, K V; Vinogradova, T A

1985-10-01

Rubidium and lithium influxes as well as intracellular potassium and sodium contents were investigated in L cells during the culture growth. In sparse culture over the cell densities 0.5-3 X 10(4) cells/cm2 ouabain-sensitive rubidium influx is small and ouabain-resistant lithium influx in high. With the increase in culture density up to 4-5 X 10(4) cells/cm2 the active rubidium influx, mediated by ouabain-sensitive component, is enhanced, and ion "leakage" tested by lithium influx is diminished. Simultaneously with the exponential growth of culture the intracellular potassium content is increased and the intracellular sodium content is decreased resulting in the higher K/Na ratio in cell. During the further transition to dense culture and in stationary state (10-17 X 10(4) cells/cm2) the sodium content and lithium influx do not change significantly, but the potassium content is decreased. The decrease in intracellular potassium is correlated with that in the portion of cells in S-phase from 27-30 to 12%. Thus, in transformed cells the density-dependent alterations in membrane cation transport are observed.

Relationship of Sodium Intake and Blood Pressure Varies With Energy Intake: Secondary Analysis of the DASH (Dietary Approaches to Stop Hypertension)-Sodium Trial.

PubMed

Murtaugh, Maureen A; Beasley, Jeannette M; Appel, Lawrence J; Guenther, Patricia M; McFadden, Molly; Greene, Tom; Tooze, Janet A

2018-05-01

Dietary Na recommendations are expressed as absolute amounts (mg/d) rather than as Na density (mg/kcal). Our objective was to determine whether the strength of the relationship of Na intake with blood pressure (BP) varied with energy intake. The DASH (Dietary Approaches to Stop Hypertension)-Sodium trial was a randomized feeding trial comparing 2 diets (DASH and control) and 3 levels of Na density. Participants with pre- or stage 1 hypertension consumed diets for 30 days in random order; energy intake was controlled to maintain body weight. This secondary analysis of 379 non-Hispanic black and white participants used mixed-effects models to assess the association of Na and energy intakes with BP. The relationships between absolute Na and both systolic and diastolic BP varied with energy intake. BP rose more steeply with increasing Na at lower energy intake than at higher energy intake ( P interaction<0.001). On the control diet with 2300 mg Na, both systolic and diastolic BP were higher (3.0 mm Hg; 95% confidence interval, 0.2-5.8; and 2.7 mm Hg; 95% confidence interval, 1.0-4.5, respectively) among those with lower energy intake (higher Na density) than among those with higher energy intake (lower Na density). The association of Na with systolic BP was stronger at lower levels of energy intake in both blacks and whites ( P <0.001). The association of Na and diastolic BP varied with energy intake only among blacks ( P =0.001). Sodium density should be considered as a metric for expressing dietary Na recommendations. © 2018 American Heart Association, Inc.

Theoretical investigation of structures and energetics of sodium adatom and its dimer on graphene: DFT study

NASA Astrophysics Data System (ADS)

Kaur, Gagandeep; Gupta, Shuchi; Rani, Pooja; Dharamvir, Keya

2015-11-01

Extensive ab initio calculations have been performed to study the energetics of a sodium (Na) atom and its dimer adsorbed on graphene using the SIESTA package Soler et al. (2002) [1] which works within a DFT(density functional theory)-GGA (generalized gradient approximation) pseudopotential framework. The adsorption energy, geometry, charge transfer, ionization potential and density of states (DOS), partial density states (PDOS) of adatom/dimer-graphene system have been calculated. After considering various sites for adsorption of Na on graphene, the center of a hexagonal ring of carbon atoms is found to be the preferred site of adsorption while the Na2 dimer prefers to rest parallel to the graphene sheet. We find insignificant energy differences among adsorption configurations involving different possible sites in parallel orientation, which implies high mobility of the dimer on the graphene sheet. We also notice only a slight distortion of the graphene sheet perpendicular to its plane upon adatom adsorption. However, some lateral displacements seen are more perceptible. Summary The adsorption energy, geometry, charge transfer, ionization potential and density of states (DOS) and PDOS of adatom/dimer-graphene system have been calculated using SIESTA package Soler et al. (2002) [1] which works within a DFT(density functional theory)-GGA (generalized gradient approximation) pseudopotential framework. Preferred site for adsorption of a sodium atom on graphene is the hollow site. For the Na dimer adsorption, we found that horizontal orientation is favored over the vertical one. From DOS plots, it is clear that graphene's states are nearly unaffected by the adsorption of Na adatom and Interaction between sodium and graphene is predominantly ionic

Characterization of Transverse Tubule Vesicles Isolated from Skeletal Muscle

DTIC Science & Technology

1984-08-20

phenylmethylsulfonylfluoride (PMSF), 15 s the Polytron was stopped and the blade quercetin , sodium azide, sodium arsenate, N- cleared of connective tissue...the absence of tors of other ATPase enzymes (oligomycin. ATP. Low-density vesic les (26 pg protein/mi) were incubated ouabain. vanadate. quercetin

Molybdenum In Cathodes Of Sodium/Metal Chloride Cells

NASA Technical Reports Server (NTRS)

Bugga, Ratnakumar V.; Attia, Alan I.; Halpert, Gerald

1992-01-01

Cyclic voltammetric curves of molybdenum wire in NaAlCl4 melt indicate molybdenum chloride useful as cathode material in rechargeable sodium/metal chloride electrochemical cells. Batteries used in electric vehicles, for electric-power load leveling, and other applications involving high energy and power densities.

Density-driven transport of gas phase chemicals in unsaturated soils

NASA Astrophysics Data System (ADS)

Fen, Chiu-Shia; Sun, Yong-tai; Cheng, Yuen; Chen, Yuanchin; Yang, Whaiwan; Pan, Changtai

2018-01-01

Variations of gas phase density are responsible for advective and diffusive transports of organic vapors in unsaturated soils. Laboratory experiments were conducted to explore dense gas transport (sulfur hexafluoride, SF6) from different source densities through a nitrogen gas-dry soil column. Gas pressures and SF6 densities at transient state were measured along the soil column for three transport configurations (horizontal, vertically upward and vertically downward transport). These measurements and others reported in the literature were compared with simulation results obtained from two models based on different diffusion approaches: the dusty gas model (DGM) equations and a Fickian-type molar fraction-based diffusion expression. The results show that the DGM and Fickian-based models predicted similar dense gas density profiles which matched the measured data well for horizontal transport of dense gas at low to high source densities, despite the pressure variations predicted in the soil column were opposite to the measurements. The pressure evolutions predicted by both models were in trend similar to the measured ones for vertical transport of dense gas. However, differences between the dense gas densities predicted by the DGM and Fickian-based models were discernible for vertically upward transport of dense gas even at low source densities, as the DGM-based predictions matched the measured data better than the Fickian results did. For vertically downward transport, the dense gas densities predicted by both models were not greatly different from our experimental measurements, but substantially greater than the observations obtained from the literature, especially at high source densities. Further research will be necessary for exploring factors affecting downward transport of dense gas in soil columns. Use of the measured data to compute flux components of SF6 showed that the magnitudes of diffusive flux component based on the Fickian-type diffusion expressions in terms of molar concentration, molar fraction and mass density fraction gradient were almost the same. However, they were greater than the result computed with the mass fraction gradient for > 24% and the DGM-based result for more than one time. As a consequence, the DGM-based total flux of SF6 was in magnitude greatly less than the Fickian result not only for horizontal transport (diffusion-dominating) but also for vertical transport (advection and diffusion) of dense gas. Particularly, the Fickian-based total flux was more than two times in magnitude as much as the DGM result for vertically upward transport of dense gas.

The Nature of Turbulence in the LITTLE THINGS Dwarf Irregular Galaxies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maier, Erin; Chien, Li-Hsin; Hollyday, Gigja

We present probability density functions and higher order (skewness and kurtosis) analyses of the galaxy-wide and spatially resolved distributions of H i column density in the LITTLE THINGS sample of dwarf irregular galaxies. This analysis follows that of Burkhart et al. for the Small Magellanic Cloud (SMC). About 60% of our sample have galaxy-wide values of kurtosis that are similar to that found for the SMC, with a range up to much higher values, and kurtosis increases with integrated star formation rate. Kurtosis and skewness were calculated for radial annuli and for a grid of 32 pixel × 32 pixel kernels acrossmore » each galaxy. For most galaxies, kurtosis correlates with skewness. For about half of the galaxies, there is a trend of increasing kurtosis with radius. The range of kurtosis and skewness values is modeled by small variations in the Mach number close to the sonic limit and by conversion of H i to molecules at high column density. The maximum H i column densities decrease with increasing radius in a way that suggests molecules are forming in the weak-field limit, where H{sub 2} formation balances photodissociation in optically thin gas at the edges of clouds.« less

Gaussian model for emission rate measurement of heated plumes using hyperspectral data

NASA Astrophysics Data System (ADS)

Grauer, Samuel J.; Conrad, Bradley M.; Miguel, Rodrigo B.; Daun, Kyle J.

2018-02-01

This paper presents a novel model for measuring the emission rate of a heated gas plume using hyperspectral data from an FTIR imaging spectrometer. The radiative transfer equation (RTE) is used to relate the spectral intensity of a pixel to presumed Gaussian distributions of volume fraction and temperature within the plume, along a line-of-sight that corresponds to the pixel, whereas previous techniques exclusively presume uniform distributions for these parameters. Estimates of volume fraction and temperature are converted to a column density by integrating the local molecular density along each path. Image correlation velocimetry is then employed on raw spectral intensity images to estimate the volume-weighted normal velocity at each pixel. Finally, integrating the product of velocity and column density along a control surface yields an estimate of the instantaneous emission rate. For validation, emission rate estimates were derived from synthetic hyperspectral images of a heated methane plume, generated using data from a large-eddy simulation. Calculating the RTE with Gaussian distributions of volume fraction and temperature, instead of uniform distributions, improved the accuracy of column density measurement by 14%. Moreover, the mean methane emission rate measured using our approach was within 4% of the ground truth. These results support the use of Gaussian distributions of thermodynamic properties in calculation of the RTE for optical gas diagnostics.

Application of multiwalled carbon nanotubes and its magnetite derivative for emulsified oil removal from produced water.

PubMed

Ibrahim, Taleb H; Sabri, Muhammad A; Khamis, Mustafa I

2018-05-10

Multiwalled carbon nanotubes and their magnetite derivatives were employed as adsorbents for emulsified oil removal from produced water. The experimental parameters for maximum emulsified oil removal efficiency and effective regeneration of these adsorbents were determined. The optimum parameters in terms of adsorbent dosage, contact time, salinity, pH and temperature were 3.0 g/L, 20.0 min, 0 ppm, 7.0 and 25°C for both adsorbents. Due to their low density, multiwalledcarbon nanotubes could not be successfully employed in packed bed columns. The magnetite derivative has a larger density and hence, for the removal of emulsified oil from produced water packed bed column studies were performed utilizing multiwalled carbon magnetite nanotubes. The packed bed column efficiency and behaviour were evaluated using Thomas, Clark, Yan et al. and Bohart and Adams models. The Yan model was found to best describe the column experimental data. The adsorbents were regenerated using n-hexane and reused several times for oil removal from produced water without any significant decrease in their initial adsorption capacities.

The Influence of Process Conditions on the Chemical Composition of Pine Wood Catalytic Pyrolysis Oils

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pereira, J.; Agblevor, F. A.; Beis, S. H.

Pine wood samples were used as model feedstock to study the properties of catalytic fast pyrolysis oils. The influence of two commercial zeolite catalysts (BASF and SudChem) and pretreatment of the pine wood with sodium hydroxide on pyrolysis products were investigated. The pyrolysis oils were first fractionated using column chromatography and characterized using GC-MS. Long chain aliphatic hydrocarbons, levoglucosan, aldehydes and ketones, guaiacols/syringols, and benzenediols were the major compounds identified in the pyrolysis oils. The catalytic pyrolysis increased the polycyclic hydrocarbons fraction. Significant decreases in phthalate derivatives using SudChem and long chain aliphatics using BASF catalyst were observed. Significant amountsmore » of aromatic heterocyclic hydrocarbons and benzene derivatives were formed, respectively, using BASF and SudChem catalysts. Guaiacyl/syringyl and benzenediols derivatives were partly suppressed by the zeolite catalysts, while the sodium hydroxide treatment enriched phenolic derivatives. Zeolite catalyst and sodium hydroxide were employed together; they showed different results for each catalyst.« less

The Influence of Process Conditions on the Chemical Composition of Pine Wood Catalytic Pyrolysis Oils

DOE PAGES

Pereira, J.; Agblevor, F. A.; Beis, S. H.

2012-01-01

Pine wood samples were used as model feedstock to study the properties of catalytic fast pyrolysis oils. The influence of two commercial zeolite catalysts (BASF and SudChem) and pretreatment of the pine wood with sodium hydroxide on pyrolysis products were investigated. The pyrolysis oils were first fractionated using column chromatography and characterized using GC-MS. Long chain aliphatic hydrocarbons, levoglucosan, aldehydes and ketones, guaiacols/syringols, and benzenediols were the major compounds identified in the pyrolysis oils. The catalytic pyrolysis increased the polycyclic hydrocarbons fraction. Significant decreases in phthalate derivatives using SudChem and long chain aliphatics using BASF catalyst were observed. Significant amountsmore » of aromatic heterocyclic hydrocarbons and benzene derivatives were formed, respectively, using BASF and SudChem catalysts. Guaiacyl/syringyl and benzenediols derivatives were partly suppressed by the zeolite catalysts, while the sodium hydroxide treatment enriched phenolic derivatives. Zeolite catalyst and sodium hydroxide were employed together; they showed different results for each catalyst.« less

Tuning the density profile of surface-grafted hyaluronan and the effect of counter-ions.

PubMed

Berts, Ida; Fragneto, Giovanna; Hilborn, Jöns; Rennie, Adrian R

2013-07-01

The present paper investigates the structure and composition of grafted sodium hyaluronan at a solid-liquid interface using neutron reflection. The solvated polymer at the surface could be described with a density profile that decays exponentially towards the bulk solution. The density profile of the polymer varied depending on the deposition protocol. A single-stage deposition resulted in denser polymer layers, while layers created with a two-stage deposition process were more diffuse and had an overall lower density. Despite the diffuse density profile, two-stage deposition leads to a higher surface excess. Addition of calcium ions causes a strong collapse of the sodium hyaluronan chains, increasing the polymer density near the surface. This effect is more pronounced on the sample prepared by two-stage deposition due to the initial less dense profile. This study provides an understanding at a molecular level of how surface functionalization alters the structure and how surface layers respond to changes in calcium ions in the solvent.

The structure of the ISM in the Zone of Avoidance by high-resolution multi-wavelength observations

NASA Astrophysics Data System (ADS)

Tóth, L. V.; Doi, Y.; Pinter, S.; Kovács, T.; Zahorecz, S.; Bagoly, Z.; Balázs, L. G.; Horvath, I.; Racz, I. I.; Onishi, T.

2018-05-01

We estimate the column density of the Galactic foreground interstellar medium (GFISM) in the direction of extragalactic sources. All-sky AKARI FIS infrared sky survey data might be used to trace the GFISM with a resolution of 2 arcminutes. The AKARI based GFISM hydrogen column density estimates are compared with similar quantities based on HI 21cm measurements of various resolution and of Planck results. High spatial resolution observations of the GFISM may be important recalculating the physical parameters of gamma-ray burst (GRB) host galaxies using the updated foreground parameters.

Detection of a new carbon-chain molecule, CCO

NASA Technical Reports Server (NTRS)

Ohishi, Masatoshi; Ishikawa, Shin-Ichi; Yamada, Chikashi; Kanamori, Hideto; Irvine, William M.; Brown, Ronald D.; Godfrey, Peter D.; Kaifu, Norio; Suzuki, Hiroko

1991-01-01

A new carbon-chain molecule, CCO 3Sigma(-), has been detected in the cold dark molecular cloud TMC-1. The excitation temperature and the column density of CCO are, respectively, about 6 K and about 6 x 10 to the 11th/sq cm. This column density corresponds to a fractional abundance relative to H2 of about 6 x 10 to the -11th. This value is two orders of magnitude less than the abundance of the related carbon-chain molecule CCS, and about half that of C3O. The formation mechanism for CCO is discussed.

CS band intensity and column densities and production rates of 15 comets

NASA Astrophysics Data System (ADS)

Sanzovo, G. C.; Singh, P. D.; Huebner, W. F.

1993-09-01

An accurate fluorescence efficiency of the CS(0,0) band and the lifetime of CS have been calculated at 1 AU heliocentric distance. Model-independent CS column densities and production rates are determined from derived fluorescent emission rates (g-factors) and lifetimes for 15 comets: Austin (1982g), Borrelly (1980i), Bradfield (1979X), Crommelin (1983n), Encke (1980), Encke (1984), Giacobini-Zinner (1984e), Halley (1982i), IRAS-Araki-Alcock (1983d), Meier (1980q), Panther (1980u), Stephan-Oterma (1980g), Tuttle (1980h), West (1975n), and Wilson (1986l).

CS band intensity and column densities and production rates of 15 comets

NASA Technical Reports Server (NTRS)

Sanzovo, G. C.; Singh, P. D.; Huebner, W. F.

1993-01-01

An accurate fluorescence efficiency of the CS(0,0) band and the lifetime of CS have been calculated at 1 AU heliocentric distance. Model-independent CS column densities and production rates are determined from derived fluorescent emission rates (g-factors) and lifetimes for 15 comets: Austin (1982g), Borrelly (1980i), Bradfield (1979X), Crommelin (1983n), Encke (1980), Encke (1984), Giacobini-Zinner (1984e), Halley (1982i), IRAS-Araki-Alcock (1983d), Meier (1980q), Panther (1980u), Stephan-Oterma (1980g), Tuttle (1980h), West (1975n), and Wilson (1986l).

Diurnal variation of stratospheric chlorine monoxide - A critical test of chlorine chemistry in the ozone layer

NASA Technical Reports Server (NTRS)

Solomon, P. M.; De Zafra, R.; Parrish, A.; Barrett, J. W.

1984-01-01

Ground-based observations of a mm-wave spectral line at 278 GHz have yielded stratospheric chlorine monoxide column density diurnal variation records which indicate that the mixing ratio and column density of this compound above 30 km are about 20 percent lower than model predictions based on 2.1 parts/billion of total stratospheric chlorine. The observed day-to-night variation is, however, in good agreement with recent model predictions, both confirming the existence of a nighttime reservoir for chlorine and verifying the predicted general rate of its storage and retrieval.

Directed self-assembly into low-density colloidal liquid crystal phases

NASA Astrophysics Data System (ADS)

Gao, Yongxiang; Romano, Flavio; Dullens, Roel P. A.; Doye, Jonathan K.; Aarts, Dirk G. A. L.

2018-01-01

Alignment of anisometric particles into liquid crystals (LCs) often results from an entropic competition between their rotational and translational degrees of freedom at dense packings. Here we show that by selectively functionalizing the heads of colloidal rods with magnetic nanoparticles this tendency can be broken to direct the particles into novel, low-density LC phases. Under an external magnetic field, the magnetic heads line up in columns whereas the nonmagnetic tails point out randomly in a plane perpendicular to the columns, forming bottle-brush-like objects; laterally, the bottle brushes are entropically stabilized against coalescence. Experiments and simulations show that upon increasing the particle density the system goes from a dilute gas to a dense two-dimensional liquid of bottle brushes with a density well below the zero-field nematic phase. Our findings offer a strategy for self-assembly into three-dimensional open phases that may find applications in switchable photonics, filtration, and light-weight materials.

Rapidly Synthesized, Few-Layered Pseudocapacitive SnS2 Anode for High-Power Sodium Ion Batteries.

PubMed

Thangavel, Ranjith; Samuthira Pandian, Amaresh; Ramasamy, Hari Vignesh; Lee, Yun-Sung

2017-11-22

The abundance of sodium resources has recently motivated the investigation of sodium ion batteries (SIBs) as an alternative to commercial lithium ion batteries. However, the low power and low capacity of conventional sodium anodes hinder their practical realization. Although most research has concentrated on the development of high-capacity sodium anodes, anodes with a combination of high power and high capacity have not been widely realized. Herein, we present a simple microwave irradiation technique for obtaining few-layered, ultrathin two-dimensional SnS 2 over graphene sheets in a few minutes. SnS 2 possesses a large number of active surface sites and exhibits high-capacity, rapid sodium ion storage kinetics induced by quick, nondestructive pseudocapacitance. Enhanced sodium ion storage at a high current density (12 A g -1 ), accompanied by high reversibility and high stability, was demonstrated. Additionally, a rationally designed sodium ion full cell coupled with SnS 2 //Na 3 V 2 (PO 4 ) 3 exhibited exceptional performance with high initial Coulombic efficiency (99%), high capacity, high stability, and a retention of ∼53% of the initial capacity even after the current density was increased by a factor of 140. In addition, a high specific energy of ∼140 Wh kg -1 and an ultrahigh specific power of ∼8.3 kW kg -1 (based on the mass of both the anode and cathode) were observed. Because of its outstanding performance and rapid synthesis, few-layered SnS 2 could be a promising candidate for practical realization of high-power SIBs.

Coronagraphic Observations of the Lunar Sodium Exosphere

NASA Astrophysics Data System (ADS)

Killen, R. M.; Johnson, J. D.; Morgan, T. H.; Potter, A. E.

2017-12-01

We have designed, built and installed a small robotic coronagraph at the Winer Observatory in Sonoita, Arizona, in order to observe the sodium exosphere out to one-half degree around the Moon. Observations are obtained remotely every available clear night from our home base at Goddard Space Flight Center. Our data encompass lunations in 2015, 2016, and 2017, thus we have a long baseline of sodium exospheric calibrated images. We employ an Andover temperature-controlled 1.5 Å wide narrow-band filter centered on the sodium D2 line, and a similar 1.5 Å filter centered blueward of the D2 line by 5 Å. Exposures of 10 minutes are required to image the sodium corona at good signal to noise. Autoguiding is performed locking onto a small bright crater each night. Following each onband-offband exposure pair, on- and off-band images of the lunar surface are collected by taking a 0.1- 0.5 second exposures with the open filter. The sodium is calibrated using the counts in the open Moon images and the Hapke function. We use both dark and bright Hapke parameters for comparison check using Mare and highlands, respectively. In order to obtain the sodium profile around the entire limb, the images are transformed using a polar transform and the profiles are extracted automatically. We have derived zenith column abundances and surface abundances around the lunar limb for each observation and we fit these observations with a 3-dimensional model. We compare our lunar model derived from these observations with the data from the spectrograph onboard the LADEE spacecraft.

On the link between column density distribution and density scaling relation in star formation regions

NASA Astrophysics Data System (ADS)

Veltchev, Todor; Donkov, Sava; Stanchev, Orlin

2017-07-01

We present a method to derive the density scaling relation ∝ L^{-α} in regions of star formation or in their turbulent vicinities from straightforward binning of the column-density distribution (N-pdf). The outcome of the method is studied for three types of N-pdf: power law (7/5≤α≤5/3), lognormal (0.7≲α≲1.4) and combination of lognormals. In the last case, the method of Stanchev et al. (2015) was also applied for comparison and a very weak (or close to zero) correlation was found. We conclude that the considered `binning approach' reflects rather the local morphology of the N-pdf with no reference to the physical conditions in a considered region. The rough consistency of the derived slopes with the widely adopted Larson's (1981) value α˜1.1 is suggested to support claims that the density-size relation in molecular clouds is indeed an artifact of the observed N-pdf.

The relationship between the galactic matter distribution, cosmic ray dynamics, and gamma ray production

NASA Technical Reports Server (NTRS)

Kniffen, D. A.; Fichtel, C. E.; Thompson, D. J.

1976-01-01

Theoretical considerations and analysis of the results of gamma ray astronomy suggest that the galactic cosmic rays are dynamically coupled to the interstellar matter through the magnetic fields, and hence the cosmic ray density should be enhanced where the matter density is greatest on the scale of galactic arms. This concept has been explored in a galactic model using recent 21 cm radio observations of the neutral hydrogen and 2.6 mm observations of carbon monoxide, which is considered to be a tracer of molecular hydrogen. The model assumes: (1) cosmic rays are galactic and not universal; (2) on the scale of galactic arms, the cosmic ray column (surface) density is proportional to the total interstellar gas column density; (3) the cosmic ray scale height is significantly larger than the scale height of the matter; and (4) ours is a spiral galaxy characterized by an arm to interarm density ratio of about 3:1.

A quantitative analysis of microplastic pollution along the south-eastern coastline of South Africa.

PubMed

Nel, H A; Froneman, P W

2015-12-15

The extent of microplastic pollution (<5mm) in the southern hemisphere, particularly southern Africa, is largely unknown. This study aimed to evaluate microplastic pollution along the south-eastern coastline of South Africa, looking at whether bays are characterised by higher microplastic densities than open stretches of coastline in both beach sediment and surf-zone water. Microplastic (mean ± standard error) densities in the beach sediment ranged between 688.9 ± 348.2 and 3308 ± 1449 particles · m(-2), while those in the water column varied between 257.9 ± 53.36 and 1215 ± 276.7 particles · m(-3). With few exceptions there were no significant spatial patterns in either the sediment or water column microplastic densities; with little differences in density between bays and the open coast (P>0.05). These data indicate that the presence of microplastics were not associated with proximity to land-based sources or population density, but rather is governed by water circulation. Copyright © 2015 Elsevier Ltd. All rights reserved.

An Inorganic Microsphere Composite for the Selective Removal of Cesium 137 from Acidic Nuclear Waste Solutions - Parts 1 and 2

DOE Office of Scientific and Technical Information (OSTI.GOV)

T. J. Tranter; T. A. Vereschchagina; V. Utgikar

2009-03-01

A new inorganic ion exchange composite for removing radioactive cesium from acidic waste streams has been developed. The new material consists of ammonium molybdophosphate, (NH4)3P(Mo3O10)4•3H2O (AMP), synthesized within hollow aluminosilicate microspheres (AMP-C), which are produced as a by-product from coal combustion. The selective cesium exchange capacity of this inorganic composite was evaluated in bench-scale column tests using simulated sodium bearing waste solution as a surrogate for the acidic tank waste currently stored at the Idaho National Laboratory (INL). Total cesium loading on the columns at saturation agreed very well with equilibrium values predicted from isotherm experiments performed previously. A numericalmore » algorithm for solving the governing partial differential equations (PDE) for cesium uptake was developed using the intraparticle mass transfer coefficient obtained from previous batch kinetic experiments. Solutions to the governing equations were generated to obtain the cesium concentration at the column effluent as a function of throughput volume using the same conditions as those used for the actual column experiments. The numerical solutions of the PDE fit the column break through data quite well for all the experimental conditions in the study. The model should therefore provide a reliable prediction of column performance at larger scales. A new inorganic ion exchange composite consisting of ammonium molybdophosphate, (NH4)3P(Mo3O10)4•3H2O (AMP), synthesized within hollow aluminosilicate microspheres (AMP-C) has been developed. Two different batches of the sorbent were produced resulting in 20% and 25% AMP loading for two and three loading cycles, respectively. The selective cesium exchange capacity of this inorganic composite was evaluated using simulated sodium bearing waste solution as a surrogate for the acidic tank waste currently stored at the Idaho National Laboratory (INL). Equilibrium isotherms obtained from these experiments were very favorable for cesium uptake and indicated maximum cesium loading of approximately 9 % by weight of dry AMP. Batch kinetic experiments were also performed to obtain the necessary data to estimate the effective diffusion coefficient for cesium in the sorbent particle. These experiments resulted in effective intraparticle cesium diffusivity coefficients of 4.99 x 10-8 cm2/min and 4.72 x 10-8 cm2/min for the 20% and 25 % AMP-C material, respectively.« less

The H I-to-H2 Transition in a Turbulent Medium

NASA Astrophysics Data System (ADS)

Bialy, Shmuel; Burkhart, Blakesley; Sternberg, Amiel

2017-07-01

We study the effect of density fluctuations induced by turbulence on the H I/H2 structure in photodissociation regions (PDRs) both analytically and numerically. We perform magnetohydrodynamic numerical simulations for both subsonic and supersonic turbulent gas and chemical H I/H2 balance calculations. We derive atomic-to-molecular density profiles and the H I column density probability density function (PDF) assuming chemical equilibrium. We find that, while the H I/H2 density profiles are strongly perturbed in turbulent gas, the mean H I column density is well approximated by the uniform-density analytic formula of Sternberg et al. The PDF width depends on (a) the radiation intensity-to-mean density ratio, (b) the sonic Mach number, and (c) the turbulence decorrelation scale, or driving scale. We derive an analytic model for the H I PDF and demonstrate how our model, combined with 21 cm observations, can be used to constrain the Mach number and driving scale of turbulent gas. As an example, we apply our model to observations of H I in the Perseus molecular cloud. We show that a narrow observed H I PDF may imply small-scale decorrelation, pointing to the potential importance of subcloud-scale turbulence driving.

Development of High Pressure Liquid Chromatographic Techniques

DTIC Science & Technology

1976-05-01

Silver tungstate was prepared by precipitation from equimolar solutions of sodium tungsten oxide (Na^Oj and silver nitrate {AgN03). The precipitate ...electro- chemical detector based on this observation. Various approaches were used. Silver iodide- tungstate was prepared in the following manner...Lamers, B. J. M., and Gerding, M. H., "A New Highly Sensitive Detection System for Peptides and Proteins in Column Effluents," J. Chrom., 66, 1972

[Isolation and purification of recombinant soluble and non-fusion angiogenesis inhibitor Kringle 5 using chromatography].

PubMed

Ma, Lina; Wu, Dan; Bian, Liujiao

2012-08-01

The Kringle 5 domain of plasminogen is one of the most potent angiogenesis inhibitors known to date, which can inhibit cell proliferation and migration efficiently. In the study, on the foundation of successful clone and expression of recombinant soluble and non-fusion angiogenesis inhibitor Kringle 5, a two-step chromatographic method, including the use of SP Sepharose Fast Flow cation exchanger and Sephacryl S-100 HR size exclusion chromatography in sequence, was established to separate and purify angiogenesis inhibitor Kringle 5. On the SP Sepharose Fast Flow column, the buffer A consisted of 50.0 mmol/L acetic acid-sodium acetate (pH 5.2), and the buffer B consisted of buffer A with the addition of 0.5 mol/L sodium chloride (pH 5.2); on Sephacryl S-100 HR column, the elution buffer was 5.0 mmol/L phosphate solution (pH 7.0). Through the two-step chromatographic purification process, the purity of the obtained Kringle 5 was more than 98%. In addition, it was found that the obtained Kringle 5 could inhibit the blood vessel growth of chick embryo chorioallantoic membrane effectively. Finally it is concluded that this method can effectively separate active recombinant soluble and non-fusion angiogenesis inhibitor Kringle 5.

New bimetallic EMF cell shows promise in direct energy conversion

NASA Technical Reports Server (NTRS)

Hesson, J. C.; Shimotake, H.

1968-01-01

Concentration cell, based upon a thermally regenerative cell principle, produces electrical energy from any large heat source. This experimental bimetallic EMF cell uses a sodium-bismuth alloy cathode and a pure liquid sodium anode. The cell exhibits reliability, corrosion resistance, and high current density performance.

Thermal Analysis for Ion-Exchange Column System

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Si Y.; King, William D.

2012-12-20

Models have been developed to simulate the thermal characteristics of crystalline silicotitanate ion exchange media fully loaded with radioactive cesium either in a column configuration or distributed within a waste storage tank. This work was conducted to support the design and operation of a waste treatment process focused on treating dissolved, high-sodium salt waste solutions for the removal of specific radionuclides. The ion exchange column will be installed inside a high level waste storage tank at the Savannah River Site. After cesium loading, the ion exchange media may be transferred to the waste tank floor for interim storage. Models weremore » used to predict temperature profiles in these areas of the system where the cesium-loaded media is expected to lead to localized regions of elevated temperature due to radiolytic decay. Normal operating conditions and accident scenarios (including loss of solution flow, inadvertent drainage, and loss of active cooling) were evaluated for the ion exchange column using bounding conditions to establish the design safety basis. The modeling results demonstrate that the baseline design using one central and four outer cooling tubes provides a highly efficient cooling mechanism for reducing the maximum column temperature. In-tank modeling results revealed that an idealized hemispherical mound shape leads to the highest tank floor temperatures. In contrast, even large volumes of CST distributed in a flat layer with a cylindrical shape do not result in significant floor heating.« less

Observation of helicon wave with m = 0 antenna in a weakly magnetized inductively coupled plasma source

NASA Astrophysics Data System (ADS)

Ellingboe, Bert; Sirse, Nishant; Moloney, Rachel; McCarthy, John

2015-09-01

Bounded whistler wave, called ``helicon wave,'' is known to produce high-density plasmas and has been exploited as a high density plasma source for many applications, including electric propulsion for spacecraft. In a helicon plasma source, an antenna wrapped around the magnetized plasma column launches a low frequency wave, ωce/2 >ωhelicon >ωce/100, in the plasma which is responsible for maintaining high density plasma. Several antenna designs have been proposed in order to match efficiently the wave modes. In our experiment, helicon wave mode is observed using an m = 0 antenna. A floating B dot probe, compensated to the capacitively coupled E field, is employed to measure axial-wave-field-profiles (z, r, and θ components) in the plasma at multiple radial positions as a function of rf power and pressure. The Bθ component of the rf-field is observed to be unaffected as the wave propagates in the axial direction. Power coupling between the antenna and the plasma column is identified and agrees with the E, H, and wave coupling regimes previously seen in M =1 antenna systems. That is, the Bz component of the rf-field is observed at low plasma density as the Bz component from the antenna penetrates the plasma. The Bz component becomes very small at medium density due to shielding at the centre of the plasma column; however, with increasing density, a sudden ``jump'' occurs in the Bz component above which a standing wave under the antenna with a propagating wave away from the antenna are observed.

Core-Shell Fe1- xS@Na2.9PS3.95Se0.05 Nanorods for Room Temperature All-Solid-State Sodium Batteries with High Energy Density.

PubMed

Wan, Hongli; Mwizerwa, Jean Pierre; Qi, Xingguo; Liu, Xin; Xu, Xiaoxiong; Li, Hong; Hu, Yong-Sheng; Yao, Xiayin

2018-03-27

High ionic conductivity electrolyte and intimate interfacial contact are crucial factors to realize high-performance all-solid-state sodium batteries. Na 2.9 PS 3.95 Se 0.05 electrolyte with reduced particle size of 500 nm is first synthesized by a simple liquid-phase method and exhibits a high ionic conductivity of 1.21 × 10 -4 S cm -1 , which is comparable with that synthesized with a solid-state reaction. Meanwhile, a general interfacial architecture, that is, Na 2.9 PS 3.95 Se 0.05 electrolyte uniformly anchored on Fe 1- x S nanorods, is designed and successfully prepared by an in situ liquid-phase coating approach, forming core-shell structured Fe 1- x S@Na 2.9 PS 3.95 Se 0.05 nanorods and thus realizing an intimate contact interface. The Fe 1- x S@Na 2.9 PS 3.95 Se 0.05 /Na 2.9 PS 3.95 Se 0.05 /Na all-solid-state sodium battery demonstrates high specific capacity and excellent rate capability at room temperature, showing reversible discharge capacities of 899.2, 795.5, 655.1, 437.9, and 300.4 mAh g -1 at current densities of 20, 50, 100, 150, and 200 mA g -1 , respectively. The obtained all-solid-state sodium batteries show very high energy and power densities up to 910.6 Wh kg -1 and 201.6 W kg -1 based on the mass of Fe 1- x S at current densities of 20 and 200 mA g -1 , respectively. Moreover, the reaction mechanism of Fe 1- x S is confirmed by means of ex situ X-ray diffraction techniques, showing that partially reversible reaction occurs in the Fe 1- x S electrode after the second cycle, which gives the obtained all-solid-state sodium battery an exceptional cycling stability, exhibiting a high capacity of 494.3 mAh g -1 after cycling at 100 mA g -1 for 100 cycles. This contribution provides a strategy for designing high-performance room temperature all-solid-state sodium battery.

GEOMETRY-INDEPENDENT DETERMINATION OF RADIAL DENSITY DISTRIBUTIONS IN MOLECULAR CLOUD CORES AND OTHER ASTRONOMICAL OBJECTS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Krčo, Marko; Goldsmith, Paul F., E-mail: marko@astro.cornell.edu

2016-05-01

We present a geometry-independent method for determining the shapes of radial volume density profiles of astronomical objects whose geometries are unknown, based on a single column density map. Such profiles are often critical to understand the physics and chemistry of molecular cloud cores, in which star formation takes place. The method presented here does not assume any geometry for the object being studied, thus removing a significant source of bias. Instead, it exploits contour self-similarity in column density maps, which appears to be common in data for astronomical objects. Our method may be applied to many types of astronomical objectsmore » and observable quantities so long as they satisfy a limited set of conditions, which we describe in detail. We derive the method analytically, test it numerically, and illustrate its utility using 2MASS-derived dust extinction in molecular cloud cores. While not having made an extensive comparison of different density profiles, we find that the overall radial density distribution within molecular cloud cores is adequately described by an attenuated power law.« less

Interstellar abundances and depletions inferred from observations of neutral atoms

NASA Technical Reports Server (NTRS)

Snow, T. P.

1984-01-01

Data on neutral atomic species are analyzed for the purpose of inferring relative elemental abundances and depletions in diffuse cloud cores, where it is assumed that densities are enhanced in comparison with mean densities over integrated lines of sight. Column densities of neutral atoms are compared to yield relative column densities of singly ionized species, which are assumed dominant in cloud cores. This paper incorporates a survey of literature data on neutral atomic abundances with the result that no systematic enhancement in the depletions of calcium or iron in cloud cores is found, except for zeta Ophiuchi. This may imply that depletions are not influenced by density, but other data argue against this interpretation. It is concluded either that in general all elements are depleted together in dense regions so that their relative abundances remain constant, or that typical diffuse clouds do not have significant cores, but instead are reasonably homogeneous. The data show a probable correlation between cloud-core depletion and hydrogen-molecular fraction, supporting the assumption that overall depletions are a function of density.

Radial Profiles of the Plasma Electron Characteristics in a 30 kW Arc Jet

NASA Technical Reports Server (NTRS)

Codron, Douglas A.; Nawaz, Anuscheh

2013-01-01

The present effort aims to strengthen modeling work conducted at the NASA Ames Research Center by measuring the critical plasma electron characteristics within and slightly outside of an arc jet plasma column. These characteristics are intended to give physical insights while assisting in the formulation of boundary conditions to validate full scale simulations. Single and triple Langmuir probes have been used to achieve estimates of the electron temperature (T(sub e)), electron number density (n(sub e)) and plasma potential (outside of the plasma column) as probing location is varied radially from the flow centerline. Both the electron temperature and electron number density measurements show a large dependence on radial distance from the plasma column centerline with T(sub e) approx. = (3 - 12 eV and n(sub e) approx. = 10(exp 12) - 10(exp 14)/cu cm.

Empirical relationships among atmospheric variables from rawinsonde and field data as surrogates for AVIRIS measurements: Estimation of regional land surface evapotranspiration

NASA Technical Reports Server (NTRS)

Conel, James E.; Hoover, Gordon; Nolin, Anne; Alley, Ron; Margolis, Jack

1992-01-01

Empirical relationships between variables are ways of securing estimates of quantities difficult to measure by remote sensing methods. The use of empirical functions was explored between: (1) atmospheric column moisture abundance W (gm H2O/cm(sup 2) and surface absolute water vapor density rho(q-bar) (gm H2O/cm(sup 3), with rho density of moist air (gm/cm(sup 3), q-bar specific humidity (gm H2O/gm moist air), and (2) column abundance and surface moisture flux E (gm H2O/(cm(sup 2)sec)) to infer regional evapotranspiration from Airborne Visible/Infrared Imaging Spectrometers (AVIRIS) water vapor mapping data. AVIRIS provides, via analysis of atmospheric water absorption features, estimates of column moisture abundance at very high mapping rate (at approximately 100 km(sup 2)/40 sec) over large areas at 20 m ground resolution.

Designing solid-liquid interphases for sodium batteries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Choudhury, Snehashis; Wei, Shuya; Ozhabes, Yalcin

Secondary batteries based on earth-abundant sodium metal anodes are desirable for both stationary and portable electrical energy storage. Room-temperature sodium metal batteries are impractical today because morphological instability during recharge drives rough, dendritic electrodeposition. Chemical instability of liquid electrolytes also leads to premature cell failure as a result of parasitic reactions with the anode. Here we use joint density-functional theoretical analysis to show that the surface diffusion barrier for sodium ion transport is a sensitive function of the chemistry of solid–electrolyte interphase. In particular, we find that a sodium bromide interphase presents an exceptionally low energy barrier to ion transport,more » comparable to that of metallic magnesium. We evaluate this prediction by means of electrochemical measurements and direct visualization studies. These experiments reveal an approximately three-fold reduction in activation energy for ion transport at a sodium bromide interphase. Direct visualization of sodium electrodeposition confirms large improvements in stability of sodium deposition at sodium bromide-rich interphases.« less

Designing solid-liquid interphases for sodium batteries

DOE PAGES

Choudhury, Snehashis; Wei, Shuya; Ozhabes, Yalcin; ...

2017-10-12

Secondary batteries based on earth-abundant sodium metal anodes are desirable for both stationary and portable electrical energy storage. Room-temperature sodium metal batteries are impractical today because morphological instability during recharge drives rough, dendritic electrodeposition. Chemical instability of liquid electrolytes also leads to premature cell failure as a result of parasitic reactions with the anode. Here we use joint density-functional theoretical analysis to show that the surface diffusion barrier for sodium ion transport is a sensitive function of the chemistry of solid–electrolyte interphase. In particular, we find that a sodium bromide interphase presents an exceptionally low energy barrier to ion transport,more » comparable to that of metallic magnesium. We evaluate this prediction by means of electrochemical measurements and direct visualization studies. These experiments reveal an approximately three-fold reduction in activation energy for ion transport at a sodium bromide interphase. Direct visualization of sodium electrodeposition confirms large improvements in stability of sodium deposition at sodium bromide-rich interphases.« less

Effects of initial saturation on properties modification and displacement of tetrachloroethene with aqueous isobutanol.

PubMed

Boyd, Glen R; Ocampo-Gómez, Ana M; Li, Minghua; Husserl, Johana

2006-11-20

Packed column experiments were conducted to study effects of initial saturation of tetrachloroethene (PCE) in the range of 1.0-14% pore volume (PV) on mobilization and downward migration of the non-aqueous phase liquid (NAPL) product upon contact with aqueous isobutanol ( approximately 10 vol.%). This study focused on the consequences of swelling beyond residual saturation. Columns were packed with mixtures of neat PCE, water and glass beads and waterflooded to establish a desired homogeneous residual saturation, and then flooded with aqueous isobutanol under controlled hydraulic conditions. Results showed a critical saturation of approximately 8% PV for these packed column experimental conditions. At low initial PCE saturations (<8% PV), experimental results showed reduced risk of NAPL-product migration upon contact with aqueous isobutanol. At higher initial PCE saturations (>8% PV), results showed NAPL-product mobilization and downward migration which was attributed to interfacial tension (IFT) reduction, swelling of the NAPL-product, and reduced density modification. Packed column results were compared with good agreement to theoretical predictions of NAPL-product mobilization using the total trapping number, N(T). In addition to the packed column study, preliminary batch experiments were conducted to study the effects of PCE volumetric fraction in the range of 0.5-20% on density, viscosity, and IFT modification as a function of time following contact with aqueous isobutanol ( approximately 10 vol.%). Modified NAPL-product fluid properties approached equilibrium within approximately 2 h of contact for density and viscosity. IFT reduction occurred immediately as expected. Measured fluid properties were compared with good agreement to theoretical equilibrium predictions based on UNIQUAC. Overall, this study demonstrates the importance of initial DNAPL saturation, and the associated risk of downward NAPL-product migration, in applying alcohol flooding for remediation of DNAPL contaminated ground water sites.

Effect of increased groundwater viscosity on the remedial performance of surfactant-enhanced air sparging

NASA Astrophysics Data System (ADS)

Choi, Jae-Kyeong; Kim, Heonki; Kwon, Hobin; Annable, Michael D.

2018-03-01

The effect of groundwater viscosity control on the performance of surfactant-enhanced air sparging (SEAS) was investigated using 1- and 2-dimensional (1-D and 2-D) bench-scale physical models. The viscosity of groundwater was controlled by a thickener, sodium carboxymethylcellulose (SCMC), while an anionic surfactant, sodium dodecylbenzene sulfonate (SDBS), was used to control the surface tension of groundwater. When resident DI water was displaced with a SCMC solution (500 mg/L), a SDBS solution (200 mg/L), and a solution with both SCMC (500 mg/L) and SDBS (200 mg/L), the air saturation for sand-packed columns achieved by air sparging increased by 9.5%, 128%, and 154%, respectively, (compared to that of the DI water-saturated column). When the resident water contained SCMC, the minimum air pressure necessary for air sparging processes increased, which is considered to be responsible for the increased air saturation. The extent of the sparging influence zone achieved during the air sparging process using the 2-D model was also affected by viscosity control. Larger sparging influence zones (de-saturated zone due to air injection) were observed for the air sparging processes using the 2-D model initially saturated with high-viscosity solutions, than those without a thickener in the aqueous solution. The enhanced air saturations using SCMC for the 1-D air sparging experiment improved the degradative performance of gaseous oxidation agent (ozone) during air sparging, as measured by the disappearance of fluorescence (fluorescein sodium salt). Based on the experimental evidence generated in this study, the addition of a thickener in the aqueous solution prior to air sparging increased the degree of air saturation and the sparging influence zone, and enhanced the remedial potential of SEAS for contaminated aquifers.

Development and application of a validated HPLC method for the analysis of dissolution samples of levothyroxine sodium drug products.

PubMed

Collier, J W; Shah, R B; Bryant, A R; Habib, M J; Khan, M A; Faustino, P J

2011-02-20

A rapid, selective, and sensitive gradient HPLC method was developed for the analysis of dissolution samples of levothyroxine sodium tablets. Current USP methodology for levothyroxine (L-T(4)) was not adequate to resolve co-elutants from a variety of levothyroxine drug product formulations. The USP method for analyzing dissolution samples of the drug product has shown significant intra- and inter-day variability. The sources of method variability include chromatographic interferences introduced by the dissolution media and the formulation excipients. In the present work, chromatographic separation of levothyroxine was achieved on an Agilent 1100 Series HPLC with a Waters Nova-pak column (250 mm × 3.9 mm) using a 0.01 M phosphate buffer (pH 3.0)-methanol (55:45, v/v) in a gradient elution mobile phase at a flow rate of 1.0 mL/min and detection UV wavelength of 225 nm. The injection volume was 800 μL and the column temperature was maintained at 28°C. The method was validated according to USP Category I requirements. The validation characteristics included accuracy, precision, specificity, linearity, and analytical range. The standard curve was found to have a linear relationship (r(2)>0.99) over the analytical range of 0.08-0.8 μg/mL. Accuracy ranged from 90 to 110% for low quality control (QC) standards and 95 to 105% for medium and high QC standards. Precision was <2% at all QC levels. The method was found to be accurate, precise, selective, and linear for L-T(4) over the analytical range. The HPLC method was successfully applied to the analysis of dissolution samples of marketed levothyroxine sodium tablets. Published by Elsevier B.V.

Development and application of a validated HPLC method for the analysis of dissolution samples of levothyroxine sodium drug products

PubMed Central

Collier, J.W.; Shah, R.B.; Bryant, A.R.; Habib, M.J.; Khan, M.A.; Faustino, P.J.

2011-01-01

A rapid, selective, and sensitive gradient HPLC method was developed for the analysis of dissolution samples of levothyroxine sodium tablets. Current USP methodology for levothyroxine (l-T4) was not adequate to resolve co-elutants from a variety of levothyroxine drug product formulations. The USP method for analyzing dissolution samples of the drug product has shown significant intra- and inter-day variability. The sources of method variability include chromatographic interferences introduced by the dissolution media and the formulation excipients. In the present work, chromatographic separation of levothyroxine was achieved on an Agilent 1100 Series HPLC with a Waters Nova-pak column (250mm × 3.9mm) using a 0.01 M phosphate buffer (pH 3.0)–methanol (55:45, v/v) in a gradient elution mobile phase at a flow rate of 1.0 mL/min and detection UV wavelength of 225 nm. The injection volume was 800 µL and the column temperature was maintained at 28 °C. The method was validated according to USP Category I requirements. The validation characteristics included accuracy, precision, specificity, linearity, and analytical range. The standard curve was found to have a linear relationship (r2 > 0.99) over the analytical range of 0.08–0.8 µg/mL. Accuracy ranged from 90 to 110% for low quality control (QC) standards and 95 to 105% for medium and high QC standards. Precision was <2% at all QC levels. The method was found to be accurate, precise, selective, and linear for l-T4 over the analytical range. The HPLC method was successfully applied to the analysis of dissolution samples of marketed levothyroxine sodium tablets. PMID:20947276

Host-pathogen interactions. XXIX. Oligogalacturonides released from sodium polypectate by endopolygalacturonic acid lyase are elicitors of phytoalexins in soybean. [Glycine max L

DOE Office of Scientific and Technical Information (OSTI.GOV)

Davis, K.R.; Darvill, A.G.; Albersheim, P.

1986-02-01

Recent studies have demonstrated that an apparently homogeneous preparation of an ..cap alpha..-1,4-D-endopolygalacturonic acid lyase (EC 4.2,2.2) isolated from the phytopathogenic bacterium Erwinia carotovora induced phytoalexin accumulation in cotyledons of soybean (Glycine max (L.) Merr. cv Wayne) and that this pectin-degrading enzyme released heat-stable elicitors of phytoalexins from soybean cell walls, citrus pectin, and sodium polypectate. The present paper reports the purification, by anion-exchange chromatography on QAE-Sephadex columns followed by gel-permeation chromatography on a Bio-Gel P-6 column, of the two fractions with highest specific elicitor activity present in a crude elicitor-preparation obtained by lyase treatment of sodium polypectate. Structural analysismore » of the fraction with highest specific elicitor activity indicated that the major, if not only, component was a decasaccharide of ..cap alpha..-1,4-D-galactosyluronic acid that contained the expected product of lyase cleavage, 4-deoxy-..beta..-L-5-threo-hexopyranos-4-enyluronic acid (4,5-unsaturated galactosyluronic acid), at the nonreducing terminus. This modified decagalacturonide fraction exhibited half-maximum and maximum elicitor activity at 1 microgram/cotyledon (6 micromolar) and 5 micrograms/cotyledon (32 micromolar) galactosyluronic acid equivalents, respectively. Reducing 90 to 95% of the carboxyl groups of the galactosyluronic acid residues abolished the elicitor activity of the decagalacturonide fraction. The second most elicitor-active fraction contained mostly undeca-..cap alpha..-1,4-D-galactosyluronic acid that contained 4,5-unsaturated galactosyluronic acid at the nonreducing termini. This fraction exhibited half-maximum and maximum elicitor activity at approximately 3 micrograms/cotyledon (17 micromolar) and 6 micrograms/cotyledon (34 micromolar) galactosyluronic acid equivalents, respectively.« less

Uncertainty and variability in laboratory derived sorption parameters of sediments from a uranium in situ recovery site

NASA Astrophysics Data System (ADS)

Dangelmayr, Martin A.; Reimus, Paul W.; Johnson, Raymond H.; Clay, James T.; Stone, James J.

2018-06-01

This research assesses the ability of a GC SCM to simulate uranium transport under variable geochemical conditions typically encountered at uranium in-situ recovery (ISR) sites. Sediment was taken from a monitoring well at the SRH site at depths 192 and 193 m below ground and characterized by XRD, XRF, TOC, and BET. Duplicate column studies on the different sediment depths, were flushed with synthesized restoration waters at two different alkalinities (160 mg/l CaCO3 and 360 mg/l CaCO3) to study the effect of alkalinity on uranium mobility. Uranium breakthrough occurred 25% - 30% earlier in columns with 360 mg/l CaCO3 over columns fed with 160 mg/l CaCO3 influent water. A parameter estimation program (PEST) was coupled to PHREEQC to derive site densities from experimental data. Significant parameter fittings were produced for all models, demonstrating that the GC SCM approach can model the impact of carbonate on uranium in flow systems. Derived site densities for the two sediment depths were between 141 and 178 μmol-sites/kg-soil, demonstrating similar sorption capacities despite heterogeneity in sediment mineralogy. Model sensitivity to alkalinity and pH was shown to be moderate compared to fitted site densities, when calcite saturation was allowed to equilibrate. Calcite kinetics emerged as a potential source of error when fitting parameters in flow conditions. Fitted results were compared to data from previous batch and column studies completed on sediments from the Smith-Ranch Highland (SRH) site, to assess variability in derived parameters. Parameters from batch experiments were lower by a factor of 1.1 to 3.4 compared to column studies completed on the same sediments. The difference was attributed to errors in solid-solution ratios and the impact of calcite dissolution in batch experiments. Column studies conducted at two different laboratories showed almost an order of magnitude difference in fitted site densities suggesting that experimental methodology may play a bigger role in column sorption behavior than actual sediment heterogeneity. Our results demonstrate the necessity for ISR sites to remove residual pCO2 and equilibrate restoration water with background geochemistry to reduce uranium mobility. In addition, the observed variability between fitted parameters on the same sediments highlights the need to provide standardized guidelines and methodology for regulators and industry when the GC SCM approach is used for ISR risk assessments.

Uncertainty and variability in laboratory derived sorption parameters of sediments from a uranium in situ recovery site.

PubMed

Dangelmayr, Martin A; Reimus, Paul W; Johnson, Raymond H; Clay, James T; Stone, James J

2018-06-01

This research assesses the ability of a GC SCM to simulate uranium transport under variable geochemical conditions typically encountered at uranium in-situ recovery (ISR) sites. Sediment was taken from a monitoring well at the SRH site at depths 192 and 193 m below ground and characterized by XRD, XRF, TOC, and BET. Duplicate column studies on the different sediment depths, were flushed with synthesized restoration waters at two different alkalinities (160 mg/l CaCO 3 and 360 mg/l CaCO 3 ) to study the effect of alkalinity on uranium mobility. Uranium breakthrough occurred 25% - 30% earlier in columns with 360 mg/l CaCO 3 over columns fed with 160 mg/l CaCO 3 influent water. A parameter estimation program (PEST) was coupled to PHREEQC to derive site densities from experimental data. Significant parameter fittings were produced for all models, demonstrating that the GC SCM approach can model the impact of carbonate on uranium in flow systems. Derived site densities for the two sediment depths were between 141 and 178 μmol-sites/kg-soil, demonstrating similar sorption capacities despite heterogeneity in sediment mineralogy. Model sensitivity to alkalinity and pH was shown to be moderate compared to fitted site densities, when calcite saturation was allowed to equilibrate. Calcite kinetics emerged as a potential source of error when fitting parameters in flow conditions. Fitted results were compared to data from previous batch and column studies completed on sediments from the Smith-Ranch Highland (SRH) site, to assess variability in derived parameters. Parameters from batch experiments were lower by a factor of 1.1 to 3.4 compared to column studies completed on the same sediments. The difference was attributed to errors in solid-solution ratios and the impact of calcite dissolution in batch experiments. Column studies conducted at two different laboratories showed almost an order of magnitude difference in fitted site densities suggesting that experimental methodology may play a bigger role in column sorption behavior than actual sediment heterogeneity. Our results demonstrate the necessity for ISR sites to remove residual pCO2 and equilibrate restoration water with background geochemistry to reduce uranium mobility. In addition, the observed variability between fitted parameters on the same sediments highlights the need to provide standardized guidelines and methodology for regulators and industry when the GC SCM approach is used for ISR risk assessments. Copyright © 2018 Elsevier B.V. All rights reserved.

High resolution mesospheric sodium properties for adaptive optics applications

NASA Astrophysics Data System (ADS)

Pfrommer, T.; Hickson, P.

2014-05-01

Context. The performance of laser guide star adaptive optics (AO) systems for large optical and infrared telescopes is affected by variability of the sodium layer, located at altitudes between 80 and 120 km in the upper mesosphere and lower thermosphere. The abundance and density structure of the atomic sodium found in this region is subject to local and global weather effects, planetary and gravity waves and magnetic storms, and is variable on time scales down to tens of milliseconds, a range relevant to AO. Aims: It is therefore important to characterize the structure and dynamical evolution of the sodium region on small, as well as large spatial and temporal scales. Parameters of particular importance for AO are the mean sodium altitude, sodium layer width and the temporal power spectrum of the centroid altitude. Methods: We have conducted a three-year campaign employing a high-resolution lidar system installed on the 6-m Large Zenith Telescope (LZT) located near Vancouver, Canada. During this period, 112 nights of useful data were obtained. Results: The vertical density profile of atomic sodium shows remarkable structure and variability. Smooth Gaussian-shaped profiles rarely occur. Multiple internal layers are frequently found. These layers often have sharp lower edges, with scale heights of just a few hundred meters, and tend to drift downwards at a typical rate of one kilometer every two to three hours. Individual layers can persist for many hours, but their density and internal structure can be highly variable. Sporadic layers are seen reaching peak densities several times the average, often in just a few minutes. Coherent vertical oscillations are often found, typically extending over tens of kilometers in altitude. Regions of turbulence are evident and Kelvin-Helmholtz instability are sometimes seen. The mean value of the centroid altitude is found to be 90.8 ± 0.1 km. The sodium layer width was determined by computing the altitude range that contains a specified fraction of the returned sodium light. We find a mean value of 13.1 ± 0.3 km for the range containing 95% of the photons, with a maximum width of 21 km. The temporal power spectral density of fluctuations of the centroid altitude is well described by a power law having an index that ranges from -1.6 to -2.3 with a mean value of -1.87 ± 0.02. This is significantly steeper than the value of -5/3 that would be expected if the dynamics were dominated by Kolmogorov turbulence, indicating that other factors such as gravity waves play an important role. The amplitude of the power spectrum has a mean value of 34+6-5~m2 Hz-1 at a frequency of 1 Hz, but ranges over two orders of magnitude. The annual means of the index and amplitude show a variation that is well beyond the calculated error range. Long-term global weather patterns may be responsible for this effect. The database is only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/565/A102

M = +1, ± 1 and ± 2 mode helicon wave excitation.

NASA Astrophysics Data System (ADS)

Kim, J.-H.; Yun, S.-M.; Chang, H.-Y.

1996-11-01

The characteristics of M=+1, ± 1 and ± 2 modes helicon wave excited using a solenoid antenna, Nagoya type III and quadrupole antenna respectively are first investigated. The solenoid antenna is constructed by winding a copper cable on a quartz discharge tube. Two dimensional cross-field measurements of ArII optical emission induced by hot electrons are made to investigate RF power deposition: Components of the wave magnetic field measured with a single-turn, coaxial magnetic probe were compared with the field patterns computed for M=+1, ± 1 and ± 2 modes. The M=+1 mode plasma produced by the solenoid antenna has a cylindrical high intensity plasma column, which center is empty. This cylindrical high intensity column results from the rotation of the cross-sectional electric field pattern (right hand circularly polarization). The radial plasma density profile has a peak at r=2.5cm with axisymmetry. It has been found that the radial profile of the plasma density is in good agreement with the computed power deposition profile. The radial profiles of the wave magnetic field are in good agreement with computations. The plasma excited by Nagoya type III antenna has two high intensity columns which results from the linear combination of M=+1 and -1 modes (i.e. plane polarization). The radial plasma density profile is in good agreement with emission intensity profile of ArII line (488nm). The plasma excited by quadrupole antenna has four high intensity columns which results from the linear combination of M=+2 and -2 modes (i.e. plane polarization). In the M=± 2 modes, the radial plasma density profile is also in good agreement with emission intensity profile of ArII line.

The Orion Fingers: H2 Temperatures and Excitation in an Explosive Outflow

NASA Astrophysics Data System (ADS)

Youngblood, Allison; France, Kevin; Ginsburg, Adam; Hoadley, Keri; Bally, John

2018-04-01

We measure H2 temperatures and column densities across the Orion Becklin-Neugebauer/Kleinmann-Low (BN/KL) explosive outflow from a set of 13 near-infrared (IR) H2 rovibrational emission lines observed with the TripleSpec spectrograph on Apache Point Observatory’s 3.5 m telescope. We find that most of the region is well characterized by a single temperature (∼2000–2500 K), which may be influenced by the limited range of upper-energy levels (6000–20,000 K) probed by our data set. The H2 column density maps indicate that warm H2 comprises 10‑5–10‑3 of the total H2 column density near the center of the outflow. Combining column density measurements for co-spatial H2 and CO at T = 2500 K, we measure a CO/H2 fractional abundance of 2 × 10‑3 and discuss possible reasons why this value is in excess of the canonical 10‑4 value, including dust attenuation, incorrect assumptions on co-spatiality of the H2 and CO emission, and chemical processing in an extreme environment. We model the radiative transfer of H2 in this region with ultraviolet (UV) pumping models to look for signatures of H2 fluorescence from H I Lyα pumping. Dissociative (J-type) shocks and nebular emission from the foreground Orion H II region are considered as possible Lyα sources. From our radiative transfer models, we predict that signatures of Lyα pumping should be detectable in near-IR line ratios given a sufficiently strong source, but such a source is not present in the BN/KL outflow. The data are consistent with shocks as the H2 heating source.

Analysis of record-breaking low ozone values during the 1997 winter over NDSC Station Lauder, New Zealand

NASA Technical Reports Server (NTRS)

Brinksma, E. J.; Meijer, Y. J.; Connor, B. J.; Manney, G. L.; Bergwerff, J. B.; Bodeker, G. E.; Boyd, I. S.; Liley, J. B.; Hogervorst, W.; Hovenier, J. W.;

Ozone column density determination from direct irradiance measurements in the ultraviolet performed by a four-channel precision filter radiometer.

PubMed

Ingold, T; Mätzler, C; Wehrli, C; Heimo, A; Kämpfer, N; Philipona, R

2001-04-20

Ultraviolet light was measured at four channels (305, 311, 318, and 332 nm) with a precision filter radiometer (UV-PFR) at Arosa, Switzerland (46.78 degrees , 9.68 degrees , 1850 m above sea level), within the instrument trial phase of a cooperative venture of the Swiss Meteorological Institute (MeteoSwiss) and the Physikalisch-Meteorologisches Observatorium Davos/World Radiation Center. We retrieved ozone-column density data from these direct relative irradiance measurements by adapting the Dobson standard method for all possible single-difference wavelength pairs and one double-difference pair (305/311 and 305/318) under conditions of cloud-free sky and of thin clouds (cloud optical depth <2.5 at 500 nm). All UV-PFR retrievals exhibited excellent agreement with those of collocated Dobson and Brewer spectrophotometers for data obtained during two months in 1999. Combining the results of the error analysis and the findings of the validation, we propose to retrieve ozone-column density by using the 305/311 single difference pair and the double-difference pair. Furthermore, combining both retrievals by building the ratio of ozone-column density yields information that is relevant to data quality control. Estimates of the 305/311 pair agree with measurements by the Dobson and Brewer instruments within 1% for both the mean and the standard deviation of the differences. For the double pair these values are in a range up to 1.6%. However, this pair is less sensitive to model errors. The retrieval performance is also consistent with satellite-based data from the Earth Probe Total Ozone Mapping Spectrometer (EP-TOMS) and the Global Ozone Monitoring Experiment instrument (GOME).

Ozone Column Density Determination From Direct Irradiance Measurements in the Ultraviolet Performed by a Four-Channel Precision Filter Radiometer

NASA Astrophysics Data System (ADS)

Ingold, Thomas; Mätzler, Christian; Wehrli, Christoph; Heimo, Alain; Kämpfer, Niklaus; Philipona, Rolf

2001-04-01

Ultraviolet light was measured at four channels (305, 311, 318, and 332 nm) with a precision filter radiometer (UV-PFR) at Arosa, Switzerland (46.78 , 9.68 , 1850 m above sea level), within the instrument trial phase of a cooperative venture of the Swiss Meteorological Institute (MeteoSwiss) and the Physikalisch-Meteorologisches Observatorium Davos /World Radiation Center. We retrieved ozone-column density data from these direct relative irradiance measurements by adapting the Dobson standard method for all possible single-difference wavelength pairs and one double-difference pair (305 /311 and 305 /318) under conditions of cloud-free sky and of thin clouds (cloud optical depth <2.5 at 500 nm). All UV-PFR retrievals exhibited excellent agreement with those of collocated Dobson and Brewer spectrophotometers for data obtained during two months in 1999. Combining the results of the error analysis and the findings of the validation, we propose to retrieve ozone-column density by using the 305 /311 single difference pair and the double-difference pair. Furthermore, combining both retrievals by building the ratio of ozone-column density yields information that is relevant to data quality control. Estimates of the 305 /311 pair agree with measurements by the Dobson and Brewer instruments within 1% for both the mean and the standard deviation of the differences. For the double pair these values are in a range up to 1.6%. However, this pair is less sensitive to model errors. The retrieval performance is also consistent with satellite-based data from the Earth Probe Total Ozone Mapping Spectrometer (EP-TOMS) and the Global Ozone Monitoring Experiment instrument (GOME).

The Mean Metal-line Absorption Spectrum of Damped Ly α Systems in BOSS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mas-Ribas, Lluís; Miralda-Escudé, Jordi; Pérez-Ràfols, Ignasi

We study the mean absorption spectrum of the Damped Ly α (DLA) population at z ∼ 2.6 by stacking normalized, rest-frame-shifted spectra of ∼27,000 DLA systems from the DR12 of the Baryon Oscillation Spectroscopic Survey (BOSS)/SDSS-III. We measure the equivalent widths of 50 individual metal absorption lines in five intervals of DLA hydrogen column density, five intervals of DLA redshift, and overall mean equivalent widths for an additional 13 absorption features from groups of strongly blended lines. The mean equivalent width of low-ionization lines increases with N {sub H} {sub i}, whereas for high-ionization lines the increase is much weaker.more » The mean metal line equivalent widths decrease by a factor ∼1.1–1.5 from z ∼ 2.1 to z ∼ 3.5, with small or no differences between low- and high-ionization species. We develop a theoretical model, inspired by the presence of multiple absorption components observed in high-resolution spectra, to infer mean metal column densities from the equivalent widths of partially saturated metal lines. We apply this model to 14 low-ionization species and to Al iii, S iii, Si iii, C iv, Si iv, N v, and O vi. We use an approximate derivation for separating the equivalent width contributions of several lines to blended absorption features, and infer mean equivalent widths and column densities from lines of the additional species N i, Zn ii, C ii*, Fe iii, and S iv. Several of these mean column densities of metal lines in DLAs are obtained for the first time; their values generally agree with measurements of individual DLAs from high-resolution, high signal-to-noise ratio spectra when they are available.« less

Estimated global nitrogen deposition using NO2 column density

USGS Publications Warehouse

Lu, Xuehe; Jiang, Hong; Zhang, Xiuying; Liu, Jinxun; Zhang, Zhen; Jin, Jiaxin; Wang, Ying; Xu, Jianhui; Cheng, Miaomiao

2013-01-01

Global nitrogen deposition has increased over the past 100 years. Monitoring and simulation studies of nitrogen deposition have evaluated nitrogen deposition at both the global and regional scale. With the development of remote-sensing instruments, tropospheric NO2 column density retrieved from Global Ozone Monitoring Experiment (GOME) and Scanning Imaging Absorption Spectrometer for Atmospheric Chartography (SCIAMACHY) sensors now provides us with a new opportunity to understand changes in reactive nitrogen in the atmosphere. The concentration of NO2 in the atmosphere has a significant effect on atmospheric nitrogen deposition. According to the general nitrogen deposition calculation method, we use the principal component regression method to evaluate global nitrogen deposition based on global NO2 column density and meteorological data. From the accuracy of the simulation, about 70% of the land area of the Earth passed a significance test of regression. In addition, NO2 column density has a significant influence on regression results over 44% of global land. The simulated results show that global average nitrogen deposition was 0.34 g m−2 yr−1 from 1996 to 2009 and is increasing at about 1% per year. Our simulated results show that China, Europe, and the USA are the three hotspots of nitrogen deposition according to previous research findings. In this study, Southern Asia was found to be another hotspot of nitrogen deposition (about 1.58 g m−2 yr−1 and maintaining a high growth rate). As nitrogen deposition increases, the number of regions threatened by high nitrogen deposits is also increasing. With N emissions continuing to increase in the future, areas whose ecosystem is affected by high level nitrogen deposition will increase.

A new all-sky map of Galactic high-velocity clouds from the 21-cm HI4PI survey

NASA Astrophysics Data System (ADS)

Westmeier, Tobias

2018-02-01

High-velocity clouds (HVCs) are neutral or ionized gas clouds in the vicinity of the Milky Way that are characterized by high radial velocities inconsistent with participation in the regular rotation of the Galactic disc. Previous attempts to create a homogeneous all-sky H I map of HVCs have been hampered by a combination of poor angular resolution, limited surface brightness sensitivity and suboptimal sampling. Here, a new and improved H I map of Galactic HVCs based on the all-sky HI4PI survey is presented. The new map is fully sampled and provides significantly better angular resolution (16.2 versus 36 arcmin) and column density sensitivity (2.3 versus 3.7 × 1018 cm-2 at the native resolution) than the previously available LAB survey. The new HVC map resolves many of the major HVC complexes in the sky into an intricate network of narrow H I filaments and clumps that were not previously resolved by the LAB survey. The resulting sky coverage fraction of high-velocity H I emission above a column density level of 2 × 1018 cm-2 is approximately 15 per cent, which reduces to about 13 per cent when the Magellanic Clouds and other non-HVC emission are removed. The differential sky coverage fraction as a function of column density obeys a truncated power law with an exponent of -0.93 and a turnover point at about 5 × 1019 cm-2. H I column density and velocity maps of the HVC sky are made publicly available as FITS images for scientific use by the community.

How well does CO emission measure the H2 mass of MCs?

NASA Astrophysics Data System (ADS)

Szűcs, László; Glover, Simon C. O.; Klessen, Ralf S.

2016-07-01

We present numerical simulations of molecular clouds (MCs) with self-consistent CO gas-phase and isotope chemistry in various environments. The simulations are post-processed with a line radiative transfer code to obtain 12CO and 13CO emission maps for the J = 1 → 0 rotational transition. The emission maps are analysed with commonly used observational methods, I.e. the 13CO column density measurement, the virial mass estimate and the so-called XCO (also CO-to-H2) conversion factor, and then the inferred quantities (I.e. mass and column density) are compared to the physical values. We generally find that most methods examined here recover the CO-emitting H2 gas mass of MCs within a factor of 2 uncertainty if the metallicity is not too low. The exception is the 13CO column density method. It is affected by chemical and optical depth issues, and it measures both the true H2 column density distribution and the molecular mass poorly. The virial mass estimate seems to work the best in the considered metallicity and radiation field strength range, even when the overall virial parameter of the cloud is above the equilibrium value. This is explained by a systematically lower virial parameter (I.e. closer to equilibrium) in the CO-emitting regions; in CO emission, clouds might seem (sub-)virial, even when, in fact, they are expanding or being dispersed. A single CO-to-H2 conversion factor appears to be a robust choice over relatively wide ranges of cloud conditions, unless the metallicity is low. The methods which try to take the metallicity dependence of the conversion factor into account tend to systematically overestimate the true cloud masses.

Using Cassini UVIS Data to Constrain Enceladus' Libration State

NASA Technical Reports Server (NTRS)

Hurford, Terry A.; Helfenstein, P.; Hansen, C.

2010-01-01

Given the non-spherical shape of Enceladus, the satellite may experience gravitational torques that will cause it to physically librate as it orbits Saturn. Physical libration would produce a diurnal oscillation in the longitude of Enceladus' tidal bulge, which could have a profound effect on the diurnal stresses experienced by the surface of the satellite. Although Cassini ISS has placed an observational upper limit on Enceladus' libration amplitude, stall amplitude librations may have geologically significant consequences. For example, a physical libration will affect heat production along the tiger stripes as produced by tidal shear heating and a previous study has explored possible libration states that provided better matches to Cassini CIRS observations of heat along the tiger stripes. Cassini UVIS stellar occultations provided measurements of the column density of the Enceladus plume at two different points in Enceladus' orbit and find comparable column density values. This column density may be a reflection of the amount of the tiger stripe rifts in tension and able to vent volatiles and a physical libration will also affect the fraction of tiger stripe in tension at different points in the orbit. We have modeled the expected fraction of tiger stripes in tension under different libration conditions. Without libration the amount of tiger stripe rifts in tension at both paints in the orbit would not be comparable and therefore may not allow comparable amounts of volatiles to escape. However, we identify libration conditions that do allow comparable amounts of the tiger stripes to be in tension at each point in the orbit, which might lead to comparable column densities. The librations identified coincide with possible librations states identified in the earlier study, which used Cassini CIRS observations.

D/H Toward BD+28 4211: First FUSE Results

NASA Technical Reports Server (NTRS)

Sonneborne, George; Andre, M.; Oliveira, C.; Friedman, S. D.; Howk, J. C.; Kruk, J. W.; Moos, H. W.; Oegerle, W. R.; Sembach, K. R.; Chayer, P.;

Investigating the physics and environment of Lyman limit systems in cosmological simulations

NASA Astrophysics Data System (ADS)

Erkal, Denis

2015-07-01

In this work, I investigate the properties of Lyman limit systems (LLSs) using state-of-the-art zoom-in cosmological galaxy formation simulations with on the fly radiative transfer, which includes both the cosmic UV background (UVB) and local stellar sources. I compare the simulation results to observations of the incidence frequency of LLSs and the H I column density distribution function over the redshift range z = 2-5 and find good agreement. I explore the connection between LLSs and their host haloes and find that LLSs reside in haloes with a wide range of halo masses with a nearly constant covering fraction within a virial radius. Over the range z = 2-5, I find that more than half of the LLSs reside in haloes with M < 1010 h-1 M⊙, indicating that absorption line studies of LLSs can probe these low-mass galaxies which H2-based star formation models predict to have very little star formation. I study the physical state of individual LLSs and test a simple model which encapsulates many of their properties. I confirm that LLSs have a characteristic absorption length given by the Jeans length and that they are in photoionization equilibrium at low column densities. Finally, I investigate the self-shielding of LLSs to the UVB and explore how the non-sphericity of LLSs affects the photoionization rate at a given N_{H I}. I find that at z ≈ 3, LLSs have an optical depth of unity at a column density of ˜1018 cm-2 and that this is the column density which characterizes the onset of self-shielding.

The Nature of the Torus in the Heavily Obscured AGN Markarian 3: an X-Ray Study

NASA Technical Reports Server (NTRS)

Guainazzi, M.; Risaliti, G.; Awaki, H.; Arevalo, P.; Bauer, F. E.; Bianchi, S.; Boggs, S.E; Brandt, W. N.; Brightman, M.; Christensen, F. E.;

Measurement of bromate in bread by liquid chromatography with post-column flow reactor detection.

PubMed

Himata, K; Noda, M; Ando, S; Yamada, Y

2000-01-01

This method is suitable for the determination of bromate residues in a variety of baked goods. The peer-verified method trial was performed on white bread, multigrain bread, and coffee cake spiked with known levels of potassium bromate. The analytical portion is extracted with deionized water to remove bromate from the bulk of the baked product. The aqueous extract is carried through a series of steps to remove co-extractives that would interfere with the liquid chromatography (LC) in the determinative step or hasten the deterioration of the LC column. The extract is filtered before passing it through a reversed-phase solid-phase extraction (SPE) column and a cation-exchange column in the silver form to remove lipids and chloride, respectively. Ultrafiltration is then used to remove proteins with molecular weights of >30,000 daltons. Finally, a cation-exchange column in the sodium form is used to remove silver ions from the extract. The determinative step uses LC with a reversed-phase column and an ion-pairing agent in the mobile phase. Detection is based on the post-column reaction of bromate with o-dianisidine to form an oxidation product that is quantitated spectrophotometrically at 450 nm. Overall agreement between the submitting and peer laboratories was quite good. For bromate levels of 10-52 ppb, overall mean recoveries were 76.9 and 78.8% for the submitting and peer laboratories, respectively. The standard deviations were higher for the results of the peer laboratory, probably because of the generally higher level of baseline noise present in the chromatograms. The results demonstrate that the method provides adequate accuracy with low-fat as well as high-fat foods. Bromate at levels as low as 5 ppb (ng/g) can be detected with the method.

Radial distribution of the flow velocity, efficiency and concentration in a wide HPLC column

DOE Office of Scientific and Technical Information (OSTI.GOV)

Farkas, T.; Sepaniak, M.J.; Guiochon, G.

1997-08-01

The use of optical fibers in a fluorescence-detection scheme permits the accurate determination of the radial distribution of the transit time, the column efficiency, and the analyte concentration at the exit of a chromatographic axial-compression column (50 mmID). The results obtained demonstrate that the column is not homogeneous, but suggest a nearly cylindrical distribution of the packing density. The average velocity close to the column wall is 7% lower than along its axis and the HETP 25% higher. The lack of homogeneity of the column packing is another source of band broadening not taken into account in chromatography so far.more » It causes the apparent HETP derived from the conventional elution chromatogram recorded on the bulk eluent to be larger than the local HETP and the band profile to be unsymmetrical with a slight tail reminiscent of kinetic tailing.« less

A {sup 13}CO SURVEY OF INTERMEDIATE-MASS STAR-FORMING REGIONS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lundquist, Michael J.; Kobulnicky, Henry A.; Kerton, Charles R.

2015-06-10

We have conducted a {sup 13}CO survey of a sample of 128 infrared color-selected intermediate-mass star-forming region (IM SFR) candidates. We utilized the Onsala 20 m telescope to observe {sup 13}CO (1–0) toward 67 northern IM SFRs, used the 12 m Atacama Pathfinder Experiment telescope to observe {sup 13}CO (2–1) toward 22 southern IM SFRs, and incorporated an additional 39 sources from the Boston University Five College Radio Astronomy Observatory Galactic Ring Survey which observed {sup 13}CO (1–0). We detect {sup 13}CO (1–0) in 58 of the 67 northern sources and {sup 13}CO (2–1) in 20 of the 22 southernmore » sources. The mean molecular column densities and {sup 13}CO linewidths in the inner Galaxy are higher by factors of 3.4 and 1.5, respectively, than the outer Galaxy. We attribute this difference to molecular clouds in the inner Galaxy being more massive and hosting star forming regions with higher luminosities on average than the outer Galaxy. IM SFRs have mean a molecular column density of 7.89 × 10{sup 21} cm{sup −2}, a factor of 3.1 lower than that for a sample of high-mass regions, and have a mean {sup 13}CO linewidth of 1.84 km s{sup −1}, a factor of 1.5 lower than that for high-mass regions. We demonstrate a correlation between {sup 13}CO linewidth and infrared luminosity as well as between molecular column density and infrared luminosity for the entire sample of intermediate-mass and high-mass regions. IM SFRs appear to form in distinctly lower-density environments with mean linewidths and beam-averaged column densities a factor of several lower than high-mass star-forming regions.« less

The early stages of massive star formation: tracing the physical and chemical conditions in hot cores

NASA Astrophysics Data System (ADS)

Calcutt, Hannah

2015-04-01

Molecules are essential to the formation of stars, by allowing radiation to escape the cloud and cooling to occur. Over 180 molecules have been detected in interstellar environments, ranging from comets to interstellar clouds. Their spectra are useful probes of the conditions in which these molecules form. Comparison of rest frequencies to observed frequencies can provide information about the velocity of gas and indicate physical structures. The density, temperature, and excitation conditions of gas can be determined directly from the spectra of molecules. Furthermore, by taking a chemical inventory of a particular object, one can gain an understanding of the chemical processes occurring within a cloud. The class of molecules known as complex molecules (>6 atoms), are of particular interest when probing the conditions in massive starforming environments, as they are observed to trace a more compact region than smaller molecules. This thesis details the work of my PhD, to explore how complex molecules can be used to trace the physical and chemical conditions in hot cores (HCs), one of the earliest stages of massive star formation. This work combines both the observations and chemical modelling of several different massive star-forming regions. We identify molecular transitions observed in the spectra of these regions, and calculate column densities and rotation temperatures of these molecules (Chapters 2 and 3). In Chapter 4, we chemically model the HCs, and perform a comparison between observational column densities and chemical modelling column densities. In Chapter 5, we look at the abundance ratio of three isomers, acetic acid, glycolaldehyde, and methyl formate, to ascertain whether this ratio can be used as an indicator of HC evolution. Finally, we explore the chemistry of the HC IRAS 17233-3606, to identify emission features in the spectra, and determine column densities and rotation temperatures of the detected molecules.

2MASS wide-field extinction maps. V. Corona Australis

NASA Astrophysics Data System (ADS)

Alves, João; Lombardi, Marco; Lada, Charles J.

2014-05-01

We present a near-infrared extinction map of a large region (~870 deg2) covering the isolated Corona Australis complex of molecular clouds. We reach a 1-σ error of 0.02 mag in the K-band extinction with a resolution of 3 arcmin over the entire map. We find that the Corona Australis cloud is about three times as large as revealed by previous CO and dust emission surveys. The cloud consists of a 45 pc long complex of filamentary structure from the well known star forming Western-end (the head, N ≥ 1023 cm-2) to the diffuse Eastern-end (the tail, N ≤ 1021 cm-2). Remarkably, about two thirds of the complex both in size and mass lie beneath AV ~ 1 mag. We find that the probability density function (PDF) of the cloud cannot be described by a single log-normal function. Similar to prior studies, we found a significant excess at high column densities, but a log-normal + power-law tail fit does not work well at low column densities. We show that at low column densities near the peak of the observed PDF, both the amplitude and shape of the PDF are dominated by noise in the extinction measurements making it impractical to derive the intrinsic cloud PDF below AK < 0.15 mag. Above AK ~ 0.15 mag, essentially the molecular component of the cloud, the PDF appears to be best described by a power-law with index -3, but could also described as the tail of a broad and relatively low amplitude, log-normal PDF that peaks at very low column densities. FITS files of the extinction maps are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/565/A18

Multichannel Porous TiO2 Hollow Nanofibers with Rich Oxygen Vacancies and High Grain Boundary Density Enabling Superior Sodium Storage Performance.

PubMed

Wu, Ying; Jiang, Yu; Shi, Jinan; Gu, Lin; Yu, Yan

2017-06-01

TiO 2 as an anode for sodium-ion batteries (NIBs) has attracted much recent attention, but poor cyclability and rate performance remain problematic owing to the intrinsic electronic conductivity and the sluggish diffusivity of Na ions in the TiO 2 matrix. Herein, a simple process is demonstrated to improve the sodium storage performance of TiO 2 by fabricating a 1D, multichannel, porous binary-phase anatase-TiO 2 -rutile-TiO 2 composite with oxygen-deficient and high grain-boundary density (denoted as a-TiO 2- x /r-TiO 2- x ) via electrospinning and subsequent vacuum treatment. The introduction of oxygen vacancies in the TiO 2 matrix enables enhanced intrinsic electronic conductivity and fast sodium-ion diffusion kinetics. The porous structure offers easy access of the liquid electrolyte and a short transport path of Na + through the pores toward the TiO 2 nanoparticle. Furthermore, the high density of grain boundaries between the anatase TiO 2 and rutile TiO 2 offer more interfaces for a novel interfacial storage. The a-TiO 2- x /r-TiO 2- x shows excellent long cycling stability (134 mAh g -1 at 10 C after 4500 cycles) and superior rate performance (93 mAh g -1 after 4500 cycles at 20 C) for sodium-ion batteries. This simple and effective process could serve as a model for the modification of other materials applied in energy storage systems and other fields. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Lack of pharmacokinetic interaction of mipomersen sodium (ISIS 301012), a 2'-O-methoxyethyl modified antisense oligonucleotide targeting apolipoprotein B-100 messenger RNA, with simvastatin and ezetimibe.

PubMed

Yu, Rosie Z; Geary, Richard S; Flaim, Joann D; Riley, Gina C; Tribble, Diane L; vanVliet, André A; Wedel, Mark K

2009-01-01

Mipomersen sodium (ISIS 301012) is a 20-mer phosphorothioate antisense oligonucleotide that is complementary to human apolipoprotein B-100 (apoB-100) messenger RNA and subsequently reduces translation of ApoB-100 protein, the major apolipoprotein of very low-density lipoprotein, intermediate-density lipoprotein and low-density lipoprotein (LDL). Mipomersen sodium is currently being studied in phase II/III clinical studies to determine its clinical utility as add-on therapy to HMG-CoA reductase inhibitors or other lipid-lowering agents in subjects with hypercholesterolaemia. The aim of this study was to characterize the pharmacokinetic interactions of mipomersen sodium with simvastatin and ezetimibe. Another aim was to evaluate the ability of mipomersen sodium to inhibit major cytochrome P450 (CYP) isoenzymes in vitro. In a phase I clinical study, ten healthy subjects per cohort received a single oral dose of simvastatin 40 mg or ezetimibe 10 mg followed by four 2-hour intravenous doses of mipomersen sodium 200 mg over an 8-day period, with simvastatin 40 mg or ezetimibe 10 mg being administered again with the last dose of mipomersen sodium. Mipomersen sodium pharmacokinetic profiles were assessed following the first dose (mipomersen sodium alone) and the last dose (mipomersen sodium in combination with simvastatin or ezetimibe). Plasma samples for measurement of simvastatin, simvastatin acid, and free and total ezetimibe concentrations were collected at various timepoints following their first and last oral dosing. A comparative pharmacokinetic analysis was performed to determine if there were any effects resulting from coadministration of mipomersen sodium with these lipid-lowering drugs. In addition to the clinical pharmacokinetic analysis, the ability of mipomersen sodium to inhibit the major CYP isoform enzymes (namely CYP1A2, CYP2C9, CYP2C19, CYP2D6 and CYP3A4) was evaluated in cryo-preserved human hepatocytes in vitro. The area under the plasma concentration-time curve (AUC) from 0 to 24 hours (AUC(24)), maximum plasma concentration and apparent elimination half-life values of mipomersen sodium were similar when administered alone and in combination with oral simvastatin or oral ezetimibe. The 90% confidence intervals of the geometric least squares means ratios (%Reference) of the mipomersen sodium AUC(24) values were 93.6, 107 when administered together with simvastatin, and 92.4, 111 when administered with ezetimibe. Therefore, there were no large deviations outside the default no-effect boundaries (80-125%) for total exposure (the AUC) of mipomersen sodium in combination with either simvastatin or ezetimibe. Similarly, large deviations outside the default no-effect boundaries were not observed for simvastatin, simvastatin acid, or free and total ezetimibe exposure in combination with mipomersen sodium. In cryo-preserved human hepatocytes, mipomersen sodium exhibited no cytotoxicity. Significant cell uptake was demonstrated by analysing cell-associated concentrations of mipomersen sodium. All evaluated enzyme activities had <10% inhibition at tested concentrations up to 800 microg/mL (approximately 100 micromol/L) of mipomersen sodium, and dose-dependent inhibition was not observed. Therefore, mipomersen sodium is not considered an inhibitor of CYP1A2, CYP2C9, CYP2C19, CYP2D6 and CYP3A4 enzyme activities. These data provide evidence that mipomersen sodium exhibits no clinically relevant pharmacokinetic interactions with the disposition and clearance of simvastatin or ezetimibe, and vice versa. Moreover, mipomersen sodium does not inhibit any of the major CYP enzymes that were evaluated. Taken together, the results from this study support the use of mipomersen sodium in combination with oral lipid-lowering agents.

Guidance for Subaqueous Dredged Material Capping.

DTIC Science & Technology

1998-06-01

from Ambrose Channel , over the contaminated sediments. At least two intermediate sur- veys and additional capping were required before capping was...organisms to a given bioturbation depth; reducing contami- nant flux rates to achieve specific sediment, pore water, or water column target...bathymetry, bottom slopes, cur- rents, water depths, water column density stratification, erosion/accretion trends, proximity to navigation channels

Red Phosphorus Nanodots on Reduced Graphene Oxide as a Flexible and Ultra-Fast Anode for Sodium-Ion Batteries.

PubMed

Liu, Yihang; Zhang, Anyi; Shen, Chenfei; Liu, Qingzhou; Cao, Xuan; Ma, Yuqiang; Chen, Liang; Lau, Christian; Chen, Tian-Chi; Wei, Fei; Zhou, Chongwu

2017-06-27

Sodium-ion batteries offer an attractive option for potential low cost and large scale energy storage due to the earth abundance of sodium. Red phosphorus is considered as a high capacity anode for sodium-ion batteries with a theoretical capacity of 2596 mAh/g. However, similar to silicon in lithium-ion batteries, several limitations, such as large volume expansion upon sodiation/desodiation and low electronic conductance, have severely limited the performance of red phosphorus anodes. In order to address the above challenges, we have developed a method to deposit red phosphorus nanodots densely and uniformly onto reduced graphene oxide sheets (P@RGO) to minimize the sodium ion diffusion length and the sodiation/desodiation stresses, and the RGO network also serves as electron pathway and creates free space to accommodate the volume variation of phosphorus particles. The resulted P@RGO flexible anode achieved 1165.4, 510.6, and 135.3 mAh/g specific charge capacity at 159.4, 31878.9, and 47818.3 mA/g charge/discharge current density in rate capability test, and a 914 mAh/g capacity after 300 deep cycles in cycling stability test at 1593.9 mA/g current density, which marks a significant performance improvement for red phosphorus anodes for sodium-ion chemistry and flexible power sources for wearable electronics.

Biomedical silver-109m isotope generator

DOEpatents

Wanek, Philip M.; Steinkruger, Frederick J.; Moody, David C.

1987-01-01

A method, composition of matter, and apparatus for producing substantially pure Ag-109m for use in biomedical imaging techniques. Cd-109, which decays with a half-life of 453 days to Ag-109m is loaded onto an ion exchange column consisting of particulate tin phosphate. After secular equilibrium is reached in about ten minutes, Ag-109m may be selectively eluted from the column by means of a physiologically acceptable aqueous buffered eluent solution of sodium thiosulfate, and either ascorbic acid or dextrose. The breakthrough of toxic Cd-109 is on the order of 1.times.10.sup.-7, which is sufficiently low to permit administration of the Ag-109m-containing eluate, with but a minor pH adjustment, directly to a human patient within a matter of seconds.

Biomedical silver-109m isotope generator

DOEpatents

Wanek, P.M.; Steinkruger, F.J.; Moody, D.C.

1985-03-05

A method, composition of matter, and apparatus for producing substantially pure Ag-109m for use in biomedical imaging techniques. Cd-109, which decays with a half-life of 453 days to Ag-109m, is loaded onto an ion exchange column consisting of particulate tin phosphate. After secular equilibrium is reached in about ten minutes, Ag-109m may be selectively eluted from the column by means of a physiologically acceptable aqueous buffered eluent solution of sodium thiosulfate, and either ascorbic acid or dextrose. The breakthrough of toxic Cd-109 is on the order of 1 x 10-7, which is sufficiently low to permit administration of the Ag-109m-containing eluate, with but a minor pH adjustment, directly to a human patient within a matter of seconds. 1 fig.

Physicochemical properties and ion-solvent interactions in aqueous sodium, ammonium, and lead acetate solution

NASA Astrophysics Data System (ADS)

Deosarkar, S. D.; Mendkudle, M. S.

2014-09-01

Densities (ρ), viscosities (η) and refractive indices ( n D) of aqueous sodium acetate (SA), ammonium acetate (AA), and lead acetate (LA) solutions have been measured for different concentrations of salts at 302.15 K. Apparent molar volumes (φv) for studied solutions were calculated from density data, and fitted to Masson's relation and partial molar volume (φ{v/o}) was determined. Viscosity data were fitted to Jones-Dole equation and viscosity A- and B-coefficients were determined. Refractive index and density data were fitted to Lorentz and Lorenz equation and specific refraction ( R D) were calculated. Behavior of various physicochemical properties indicated presence of strong ion-solvent interactions in present systems and the acetate salts structure maker in water.

Molecular dynamics simulation of sodium aluminosilicate glass structures and glass surface-water reactions using the reactive force field (ReaxFF)

NASA Astrophysics Data System (ADS)

Dongol, R.; Wang, L.; Cormack, A. N.; Sundaram, S. K.

2018-05-01

Reactive potentials are increasingly used to study the properties of glasses and glass water reactions in a reactive molecular dynamics (MD) framework. In this study, we have simulated a ternary sodium aluminosilicate glass and investigated the initial stages of the glass surface-water reactions at 300 K using reactive force field (ReaxFF). On comparison of the simulated glass structures generated using ReaxFF and classical Buckingham potentials, our results show that the atomic density profiles calculated for the surface glass structures indicate a bond-angle distribution dependency. The atomic density profiles also show higher concentrations of non-bridging oxygens (NBOs) and sodium ions at the glass surface. Additionally, we present our results of formation of silanol species and the diffusion of water molecules at the glass surface using ReaxFF.

Theoretical Study of Sodium Effect on the Gasification of Carbonaceous Materials with Carbon Dioxide.

PubMed

Calderón, Lucas A; Garza, Jorge; Espinal, Juan F

2015-12-24

The effect of sodium on the thermodynamics and kinetics of carbon gasification with carbon dioxide was studied by using quantum chemistry methods. Specifically, in the density functional context, two exchange-correlation functionals were used: B3LYP and M06. Some results obtained by these exchange-correlation functionals were contrasted with those obtained by the CCSD(T) method. It was found that density functional theory gives similar conclusions with respect to the coupled-cluster method. As one important conclusion we can mention that the thermodynamics of carbon monoxide desorption is not favored by the sodium presence. However, the presence of this metal induces: (a) an easier formation of one semiquinone group, (b) the dissociation of carbon dioxide, and (c) an increment on the CO desorption rate for one of the proposed pathways.

The Association of Dietary and Urinary Sodium With Bone Mineral Density and Risk of Osteoporosis: A Systematic Review and Meta-Analysis.

PubMed

Fatahi, Somaye; Namazi, Nazli; Larijani, Bagher; Azadbakht, Leila

2018-04-04

Although some earlier studies have indicated an association between dietary/urinary sodium and bone mass density (BMD), bone mass content (BMC), and the risk of osteoporosis (OS), findings are still conflicting. The aim of this study was to summarize the relation of dietary/urinary sodium with BMD, BMC, and the risk of OS. We conducted a systematic search up to April 2017 in PubMed/MEDLINE, SCOPUS, and Web of Science to find relevant studies. Articles with cross-sectional and cohort designs in which odds ratios (ORs), correlations (r), or beta coefficients were reported for the association between dietary/urinary sodium and OS, BMD, or BMC were included. Pooling 11 effect sizes with a total of 39,065 people showed that higher sodium consumption significantly increased the risk of OS (OR = 1.20; 95% confidence interval [CI], 1.02-1.41; p = 0.026), with high heterogeneity among studies (I 2 = 68.0%; p = 0.001). Subgroup analyses showed significantly higher risk of OS in premenopausal women (OR = 1.31; 95% CI, 1.01-1.69; p = 0.036), in participants with a mean age older than 50 years (OR = 1.15; 95% CI, 1.04-1.28; p = 0.005), in dietary sodium intake subgroup (OR = 1.45; 95% CI, 1.19-1.77; p < 0.001), and in individuals with adjustment for energy (OR = 1.77; 95% CI, 1.38-2.27; p < 0.001). The correlation coefficients showed no significant association between urinary sodium and BMD (r = -0.46; 95% CI, -0.74 to -0.18; p = 0.02). We found a positive association between sodium intake and the risk of OS, while no association was found with urinary sodium. Furthermore, there was no significant correlation between sodium intake and BMD. Due to high heterogeneity in this research, more studies are suggested.

A high-capacity, low-cost layered sodium manganese oxide material as cathode for sodium-ion batteries.

PubMed

Guo, Shaohua; Yu, Haijun; Jian, Zelang; Liu, Pan; Zhu, Yanbei; Guo, Xianwei; Chen, Mingwei; Ishida, Masayoshi; Zhou, Haoshen

2014-08-01

A layered sodium manganese oxide material (NaMn3 O5 ) is introduced as a novel cathode materials for sodium-ion batteries. Structural characterizations reveal a typical Birnessite structure with lamellar stacking of the synthetic nanosheets. Electrochemical tests reveal a particularly large discharge capacity of 219 mAh g(-1) in the voltage rang of 1.5-4.7 V vs. Na/Na(+) . With an average potential of 2.75 V versus sodium metal, layered NaMn3 O5 exhibits a high energy density of 602 Wh kg(-1) , and also presents good rate capability. Furthermore, the diffusion coefficient of sodium ions in the layered NaMn3 O5 electrode is investigated by using the galvanostatic intermittent titration technique. The results greatly contribute to the development of room-temperature sodium-ion batteries based on earth-abundant elements. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

[Effect of imidapril on the effective refractory period and sodium current of ventricular noninfarction zone in healed myocardial infarction].

PubMed

Li, Yang; Niu, Hui-Yan; Liu, Nian; Zhang, Cun-Tai; Lu, Zai-Ying; Wang, Shi-Wen

2005-07-01

To investigate the effects of imidapril (IMI) on effective refractory period (ERP) and sodium current (I(Na)) of myocytes in ventricular noninfarction zone of healed myocardial infarction (HMI) in rabbit models. Rabbits with left coronary artery ligation were prepared and IMI (0.625 mg x kg(-1) x d(-1), 8 weeks) was orally administered. The ERP and sodium current were recorded. The ERP in HMI heart was prolonged. The ERP in IMI group was lower significantly than that of HMI group. The I(Na) density of myocyte in HMI ventricle decreased obviously. V 1/2 of steady state inactivation of I(Na) shifted to hyperpolarization, and time constant (tau) of recovery from inactivation in HMI ventricular myocyte was longer than that of sham ventricular myocyte. I(Na) density in IMI group increased markedly as compared with that of HMI group. IMI was shown to reverse the abnormal prolongation of ERP in rabbit heart with the HMI and increase I(Na) density. It may be the mechanism of IMI preventing against antiarrhythmia in healed myocardical infarction.

[Study on preparation of composite nano-scale Fe3O4 for phosphorus control].

PubMed

Li, Lei; Pan, Gang; Chen, Hao

2010-03-01

Composite nano-scale Fe3O4 particles were prepared in sodium carboxymethyl cellulose (CMC) solution by the oxidation deposition method. The adsorptions of phosphorus by micro-scale Fe3O4 and composite nano-scale Fe3O4 were investigated in water and soil, and the role of cellulase in the adsorption of composite nano-scale Fe3O4 was studied. Kinetic tests indicated that the equilibrium adsorption capacity of phosphorous on the composite nano-scale Fe3O4 (2.1 mg/g) was less than that of micro-scale Fe3O4 (3.2 mg/g). When cellulase was added to the solution of composite nano-scale Fe3O4 to degrade CMC, the removal rate of P by the nanoparticles (86%) was enhanced to the same level as the microparticles (90%). In the column tests, when the composite nano-scale Fe3O4 suspension was introduced in the downflow mode through the soil column, 72% of Fe3O4 penetrated through the soil bed under gravity. In contrast, the micro-scale Fe3O4 failed to pass through the soil column. The retention rate of P was 45% in the soil column when treated by the CMC-stabilized nanoparticles, in comparison with only 30% for the untreated soil column, however it could be improved to 74% in the soil column when treated by both the CMC-stabilized nanoparticles and cellulase, which degraded CMC after the nanoparticles were delivered into the soil.

[Determination of lead in edible salt with solid-phase extraction and GFAAS].

PubMed

Zhao, Xin; Zhou, Shuang; Ma, Lan; Yang, Dajin

2013-01-01

Establishing a method for determination of lead in salt with solid-phase extraction and GFAAS. Salt sample was diluted to a certain volume directly with ammonium acetate, then the sample solution was filtered through the solid phase extraction column which has been pre-activated. Lead ions were retained, and the sodium chloride matrix was removed. After elution, the collected lead ions was determined by graphite furnace atomic absorption spectrometry in 257.4 nm. This method can be used effectively to wipe off the sodium chloride in matrix. The limit of detection was 0.7 microg/kg and the limit of quantification was 2 microg/kg. Solid phase extraction technique can be used effectively to reduce the interference in matrix and improves the accuracy and reproducibility of detection.

From lithium to sodium: cell chemistry of room temperature sodium-air and sodium-sulfur batteries.

PubMed

Adelhelm, Philipp; Hartmann, Pascal; Bender, Conrad L; Busche, Martin; Eufinger, Christine; Janek, Juergen

2015-01-01

Research devoted to room temperature lithium-sulfur (Li/S8) and lithium-oxygen (Li/O2) batteries has significantly increased over the past ten years. The race to develop such cell systems is mainly motivated by the very high theoretical energy density and the abundance of sulfur and oxygen. The cell chemistry, however, is complex, and progress toward practical device development remains hampered by some fundamental key issues, which are currently being tackled by numerous approaches. Quite surprisingly, not much is known about the analogous sodium-based battery systems, although the already commercialized, high-temperature Na/S8 and Na/NiCl2 batteries suggest that a rechargeable battery based on sodium is feasible on a large scale. Moreover, the natural abundance of sodium is an attractive benefit for the development of batteries based on low cost components. This review provides a summary of the state-of-the-art knowledge on lithium-sulfur and lithium-oxygen batteries and a direct comparison with the analogous sodium systems. The general properties, major benefits and challenges, recent strategies for performance improvements and general guidelines for further development are summarized and critically discussed. In general, the substitution of lithium for sodium has a strong impact on the overall properties of the cell reaction and differences in ion transport, phase stability, electrode potential, energy density, etc. can be thus expected. Whether these differences will benefit a more reversible cell chemistry is still an open question, but some of the first reports on room temperature Na/S8 and Na/O2 cells already show some exciting differences as compared to the established Li/S8 and Li/O2 systems.

Preparative liquid column electrophoresis of T and B lymphocytes at gravity = 1

NASA Technical Reports Server (NTRS)

Van Oss, C. J.; Bigazzi, P. E.; Gillman, C. F.; Allen, R. E.

1974-01-01

Vertical liquid columns containing low-molecular-weight dextran density gradients can be used for preparative lymphocyte electrophoresis on earth, in simulation of zero gravity conditions. Another method that has been tested at 1 g, is the electrophoresis of lymphocytes in an upward direction in vertical columns. By both methods up to 100 million lymphocytes can be separated at one time in a 30-cm glass column of 8-mm inside diameter, at 12 V/cm, in two hours. Due to convection and sedimentation problems, the separation at 1 g is less than ideal, but it is expected that at zero gravity electrophoresis will probe to be a uniquely powerful cell separation tool.

Isolation and separation of physicochemically distinct fimbrial types expressed on a single culture of Escherichia coli O7:K1:H6.

PubMed Central

Karch, H; Leying, H; Büscher, K H; Kroll, H P; Opferkuch, W

1985-01-01

The fimbrial (pili) profile of a single strain of Escherichia coli O7:K1:H6 (WF96) was evaluated. Fimbriae were isolated by sucrose density gradient ultracentrifugation, purified from flagellae by the use of 0.4% sodium dodecyl sulfate (SDS), and separated into distinct fimbrial types. Analysis of the purified WF96 fimbriae by SDS-polyacrylamide gel electrophoresis revealed two polypeptide bands with molecular weights of 16,000 and 21,000. Treatment of the fimbrial mixture with saturated guanidine hydrochloride resulted in the appearance of a third band with a molecular weight of 19,500. The relative susceptibilities of the WF96 fimbrial types to disrupting chemicals (octyl-glucoside, urea, SDS, and guanidine hydrochloride) were assessed by exposure of the fimbrial mixture to each agent, separation of the depolymerized fimbriae from intact fimbriae by gel filtration on Sepharose CL-4B, and identification of the disaggregated fimbrial types by SDS-polyacrylamide gel electrophoresis of column fractions. The physicochemical heterogeneity of the three fimbrial types coexpressed on WF96 was exploited to develop a method for separation of individual fimbriae. Images PMID:2857155

An Apparatus for Coating Ceramic Monofilaments Via Chemical Vapor Deposition

DTIC Science & Technology

1992-05-01

scrubber consists of sodium hydroxide suspended on diatomaceous earth particle and must be moistened before use. There is a water reservoir inside through...which an inert gas can be directed to moisturize the adsorbent . This will also help purge residual air from the scrubber. Both columns in the scrubber...The exhaust scrubber also should be serviced at regular intervals. The adsorbent canisters must be monitored to ensure that they are not completely

Biodegradation of Jet Fuel in Vented Columns of Water-Unsaturated Sandy Soil

DTIC Science & Technology

1990-01-01

phosphorus, sulfur, iron, magnesium, calcium, sodium and other elements are required for microbial growth ( Atlas , 1977). Dibble and Bartha (1979b...371-386. Bartha , R. 1986. Biotechnology of Petroleum Pollutant Biodegradation. Microbial Ecology . v.12, p.155-172. Batchelder, G.V., W.A. Panzeri...E.L. Schmidt. 1978. Limiting Factors for Microbial Growth and Activity in Soil, in Advances in Microbial Ecology , v.2, Plenum Press, New York. p.49

Surveying the H I Content of the Galactic Halo via Lyman Series Absorption

NASA Astrophysics Data System (ADS)

Fox, Andrew

The halo of the Milky Way is home to a population of gaseous high-velocity clouds (HVCs) that trace the exchange of matter between the Galaxy and its surroundings. HVCs have been studied extensively via H I 21 cm emission and UV metal-line absorption. Here we propose a third, complementary approach for studying HVCs: surveying them in UV Lyman series H I absorption using all AGN spectra in the FarUltraviolet Spectroscopic Explorer (FUSE) archive. This H I survey will constitute a metal-independent view of the baryons in the Galactic halo at a level over 1000 times more sensitive than 21 cm surveys, and it can be conducted with archival data alone. 67 AGN are available in the FUSE archives with suitable properties (S/N>4 at 977 A), and the data are reduced and ready for analysis. With these data, we will calculate HVC sky covering fractions in H I absorption and conduct HVC metallicity measurements in sightlines with UV metal absorption in HST/COS or HST/STIS spectra. We will calculate the Galactic H I column density distribution function (CDDF), the incidence of H I clouds per unit column density that encodes underlying density and ionization variations and is sensitive to the escaping ionization radiation field. The CDDF has been measured at high redshifts over eight orders of magnitude of H I column density via quasar-absorption line experiments. However, the Galactic H I CDDF has until now only been constrained at high H I column density where HVCs can be seen in 21cm emission. Our detailed work plan will involve identifying and modeling HVC absorption in ten Lyman series lines from Ly gamma 972 to Ly mu 917 in each sight line in the FUSE sample. This will constrain the H I CDDF in the column density range log N(H I) 14 to 18. By combining with the existing H I CDDF in 21 cm HVCs in the range log N(H I) 18 to 21 from the all-sky GASS survey, we will produce a global Galactic CDDF complete over seven orders of magnitude, providing key new information on the distribution of diffuse gas in the Galactic halo. This will allow us to place the Milky Way s halo in the context of those of external galaxies, and to identify the galactic contribution from bound gas in halos to the extragalactic CDDF.

Modeling the efficacy of triplet antimicrobial combinations: yeast suppression by lauric arginate, cinnamic acid, and sodium benzoate or potassium sorbate as a case study.

PubMed

Dai, Yumei; Normand, Mark D; Weiss, Jochen; Peleg, Micha

2010-03-01

The growth of four spoilage yeasts, Saccharomyces cerevisiae, Zygosaccharomyces bailii, Brettanomyces bruxellensis, and Brettanomyces naardenensis, was inhibited with three-agent (triplet) combinations of lauric arginate, cinnamic acid, and sodium benzoate or potassium sorbate. The inhibition efficacy was determined by monitoring the optical density of yeast cultures grown in microtiter plates for 7 days. The relationship between the optical density and the sodium benzoate and potassium sorbate concentrations followed a single-term exponential decay model. The critical effective concentration was defined as the concentration at which the optical density was 0.05, which became an efficacy criterion for the mixtures. Critical concentrations of sodium benzoate or potassium sorbate as a function of the lauric arginate and cinnamic acid concentrations were then fitted with an empirical model that mapped three-agent combinations of equal efficacy. The contours of this function are presented in tabulated form and as two- and three-dimensional plots. Triplet combinations were highly effective against all four spoilage yeasts at three practical pH levels, especially at pH 3.0. The triplet combinations were particularly effective for inhibiting growth of Z. bailii, and combinations containing potassium sorbate had synergistic activities. The equal efficacy concentration model also allowed tabulation of the cost of the various combinations of agents and identification of those most economically feasible.

Electric discharge synthesis of HCN in simulated Jovian atmospheres

NASA Technical Reports Server (NTRS)

Stribling, Roscoe; Miller, Stanley L.

1987-01-01

Corona discharge is presently considered as a possible source of the HCN detected in the Jovian atmosphere at 2.2 x 10 to the -7th moles/sq cm column density, for the cases of gas mixtures containing H2, CH4, and NH3, with H2/CH4 ratios from 4.4 to 1585. A 3:1 ratio of corona discharge to lightning energy similar to that of the earth is applied to Jupiter. Depending on the lightning energy available on Jupiter and the eddy diffusion coefficients in the synthesis region, HCN column densities generated by corona discharge could account for about 10 percent of the HCN observed.

I(CO)/N(H2) conversions and molecular gas abundances in spiral and irregular galaxies

NASA Technical Reports Server (NTRS)

Maloney, Philip; Black, John H.

1988-01-01

Observations of emission in the J = 1-0 rotational transition of interstellar CO are used to obtain column densities and masses of hydrogen. By taking into account the effects of variations in molecular cloud parameters on conversion factors between integrated CO intensity and molecular hydrogen column density, it is shown that conversion factors are very sensitive to the kinetic temperature of the emitting gas. Results indicate that the gas temperatures in systems with high star formation rates can be quite high, and it is suggested that use of a standard conversion factor will lead to systematic overestimation of the amount of molecular gas.

A Herschel-SPIRE Survey of the MonR2 Giant Molecular Cloud

NASA Astrophysics Data System (ADS)

Pokhrel, Riwaj; Gutermuth, Robert A.; Ali, Babar; Megeath, S. Thomas; Pipher, Judith; Myers, Philip C.; Fischer, William J.; Henning, Thomas; Wolk, Scott J.; Allen, Lori; Tobin, John J.

2014-06-01

We present a new survey of the MonR2 giant molecular cloud with SPIRE on the Herschel Space Observatory. We cross-calibrated SPIRE data with Planck-HFI and accounted for its absolute offset and zero point correction. We fixed emissivity with the help of flux-error and flux ratio plots. As the best representation of cold dusty molecular clouds, we did greybody fits of the SEDs. We studied the nature of distribution of column densities above and below certain critical limit, followed by the mass and temperature distributions for different regions. We isolated the filaments and studied radial column density profile in this cloud.

A Multi-Wavelength Study of the Hot Component of the Interstellar Medium

NASA Technical Reports Server (NTRS)

Nichols, Joy; Oliversen, Ronald K. (Technical Monitor)

2002-01-01

The goals of this research are as follows: (1) Using the large number of lines of sight available in the ME database, identify the lines of sight with high-velocity components in interstellar lines, from neutral species through Si VI, C IV, and N V; (2) Compare the column density of the main components (i.e. low velocity components) of the interstellar lines with distance, galactic longitude and latitude, and galactic radial position. Derive statistics on the distribution of components in space (e.g. mean free path, mean column density of a component). Compare with model predictions for the column densities in the walls of old SNR bubbles and superbubbles, in evaporating cloud boundaries and in turbulent mixing layers; (3) For the lines of sight associated with multiple high velocity, high ionization components, model the shock parameters for the associated superbubble and SNR to provide more accurate energy input information for hot phase models and galactic halo models. Thus far 49 lines of sight with at least one high velocity component to the C IV lines have been identified; and (4) Obtain higher resolution data for the lines of sight with high velocity components (and a few without) to further refine these models.

Rapid ionization of the environment of SN 1987A

NASA Technical Reports Server (NTRS)

Raga, A. C.

1987-01-01

It has been suggested by some authors that IUE observations of the supernova SN 1987A show the presence of a strong component of the interstellar C IV 1550 and Si IV 1393 absorption lines at a velocity that approximately corresponds to the velocity of the LMC. It is possible that this component might come from originally neutral (or at least not very highly ionized) gas which has been photoionized by the initially very strong ionizing radiation field of the supernova. Theoretical considerations of this scenario lead to the study of fast (with velocities of about c) ionization fronts. It is shown that for reasonable model parameters it is possible to obtain considerably large C IV column densities, in agreement with the IUE observations. On the other hand, the models do not so easily predict the large Si IV column densities that are also obtained from the IUE observations. It is found that only models in which the interstellar medium surrounding SN 1987A is initially composed of already ionized hydrogen and helium predict substantial Si IV column densities. This result provides an interesting prediction of the ionization state of the environment of the presupernova star.

Wide-field SCUBA-2 observations of NGC 2264: submillimetre clumps and filaments

NASA Astrophysics Data System (ADS)

Buckle, J. V.; Richer, J. S.

2015-10-01

We present wide-field observations of the NGC 2264 molecular cloud in the dust continuum at 850 and 450 μm using SCUBA-2 on the James Clerk Maxwell Telescope. Using 12CO 3 → 2 molecular line data, we determine that emission from CO contaminates the 850 μm emission at levels ˜30 per cent in localized regions associated with high-velocity molecular outflows. Much higher contamination levels of 60 per cent are seen in shocked regions near the massive star S Mon. If not removed, the levels of CO contamination would contribute an extra 13 per cent to the dust mass in NGC 2264. We use the FELLWALKER routine to decompose the dust into clumpy structures, and a Hessian-based routine to decompose the dust into filamentary structures. The filaments can be described as a hub-filament structure, with lower column density filaments radiating from the NGC 2264 C protocluster hub. Above mean filament column densities of 2.4 × 1022 cm-2, star formation proceeds with the formation of two or more protostars. Below these column densities, filaments are starless, or contain only a single protostar.

Optical observations of nearby interstellar gas

NASA Astrophysics Data System (ADS)

Frisch, P. C.; York, D. G.

1984-11-01

Observations indicated that a cloud with a heliocentric velocity of approximately -28 km/s and a hydrogen column density that possibly could be on the order of, or greater than, 5 x 10 to the 19 power/square cm is located within the nearest 50 to 80 parsecs in the direction of Ophiuchus. This is a surprisingly large column density of material for this distance range. The patchy nature of the absorption from the cloud indicates that it may not be a feature with uniform properties, but rather one with small scale structure which includes local enhancements in the column density. This cloud is probably associated with the interstellar cloud at about the same velocity in front of the 20 parsec distant star alpha Oph (Frisch 1981, Crutcher 1982), and the weak interstellar polarization found in stars as near as 35 parsecs in this general region (Tinbergen 1982). These data also indicate that some portion of the -14 km/s cloud also must lie within the 100 parsec region. Similar observations of both Na1 and Ca2 interstellar absorption features were performed in other lines of sight. Similar interstellar absorption features were found in a dozen stars between 20 and 100 parsecs of the Sun.

Optical Observations of Nearby Interstellar Gas

NASA Technical Reports Server (NTRS)

Frisch, P. C.; York, D. G.

1984-01-01

Observations indicated that a cloud with a heliocentric velocity of approximately -28 km/s and a hydrogen column density that possibly could be on the order of, or greater than, 5 x 10 to the 19 power/square cm is located within the nearest 50 to 80 parsecs in the direction of Ophiuchus. This is a surprisingly large column density of material for this distance range. The patchy nature of the absorption from the cloud indicates that it may not be a feature with uniform properties, but rather one with small scale structure which includes local enhancements in the column density. This cloud is probably associated with the interstellar cloud at about the same velocity in front of the 20 parsec distant star alpha Oph (Frisch 1981, Crutcher 1982), and the weak interstellar polarization found in stars as near as 35 parsecs in this general region (Tinbergen 1982). These data also indicate that some portion of the -14 km/s cloud also must lie within the 100 parsec region. Similar observations of both Na1 and Ca2 interstellar absorption features were performed in other lines of sight. Similar interstellar absorption features were found in a dozen stars between 20 and 100 parsecs of the Sun.

Column Number Density Expressions Through M = 0 and M = 1 Point Source Plumes Along Any Straight Path

NASA Technical Reports Server (NTRS)

Woronowicz, Michael

2016-01-01

Analytical expressions for column number density (CND) are developed for optical line of sight paths through a variety of steady free molecule point source models including directionally-constrained effusion (Mach number M = 0) and flow from a sonic orifice (M = 1). Sonic orifice solutions are approximate, developed using a fair simulacrum fitted to the free molecule solution. Expressions are also developed for a spherically-symmetric thermal expansion (M = 0). CND solutions are found for the most general paths relative to these sources and briefly explored. It is determined that the maximum CND from a distant location through directed effusion and sonic orifice cases occurs along the path parallel to the source plane that intersects the plume axis. For the effusive case this value is exactly twice the CND found along the ray originating from that point of intersection and extending to infinity along the plume's axis. For sonic plumes this ratio is reduced to about 4/3. For high Mach number cases the maximum CND will be found along the axial centerline path. Keywords: column number density, plume flows, outgassing, free molecule flow.

Seasonal variability of the hydrogen exosphere of Mars

NASA Astrophysics Data System (ADS)

Halekas, J. S.

2017-05-01

The Mars Atmosphere and Volatile EvolutioN (MAVEN) mission measures both the upstream solar wind and collisional products from energetic neutral hydrogen atoms that precipitate into the upper atmosphere after their initial formation by charge exchange with exospheric hydrogen. By computing the ratio between the densities of these populations, we derive a robust measurement of the column density of exospheric hydrogen upstream of the Martian bow shock. By comparing with Chamberlain-type model exospheres, we place new constraints on the structure and escape rates of exospheric hydrogen, derived from observations sensitive to a different and potentially complementary column from most scattered sunlight observations. Our observations provide quantitative estimates of the hydrogen exosphere with nearly complete temporal coverage, revealing order of magnitude seasonal changes in column density and a peak slightly after perihelion, approximately at southern summer solstice. The timing of this peak suggests either a lag in the response of the Martian atmosphere to solar inputs or a seasonal effect driven by lower atmosphere dynamics. The high degree of seasonal variability implied by our observations suggests that the Martian atmosphere and the thermal escape of light elements depend sensitively on solar inputs.

Evolution of column density distributions within Orion A⋆

NASA Astrophysics Data System (ADS)

Stutz, A. M.; Kainulainen, J.

2015-05-01

We compare the structure of star-forming molecular clouds in different regions of Orion A to determine how the column density probability distribution function (N-PDF) varies with environmental conditions such as the fraction of young protostars. A correlation between the N-PDF slope and Class 0 protostar fraction has been previously observed in a low-mass star-formation region (Perseus); here we test whether a similar correlation is observed in a high-mass star-forming region. We used Herschel PACS and SPIRE cold dust emission observations to derive a column density map of Orion A. We used the Herschel Orion Protostar Survey catalog to accurately identify and classify the Orion A young stellar object content, including the cold and relatively short-lived Class 0 protostars (with a lifetime of ~0.14 Myr). We divided Orion A into eight independent regions of 0.25 square degrees (13.5 pc2); in each region we fit the N-PDF distribution with a power law, and we measured the fraction of Class 0 protostars. We used a maximum-likelihood method to measure the N-PDF power-law index without binning the column density data. We find that the Class 0 fraction is higher in regions with flatter column density distributions. We tested the effects of incompleteness, extinction-driven misclassification of Class 0 sources, resolution, and adopted pixel-scales. We show that these effects cannot account for the observed trend. Our observations demonstrate an association between the slope of the power-law N-PDF and the Class 0 fractions within Orion A. Various interpretations are discussed, including timescales based on the Class 0 protostar fraction assuming a constant star-formation rate. The observed relation suggests that the N-PDF can be related to an evolutionary state of the gas. If universal, such a relation permits evaluating the evolutionary state from the N-PDF power-law index at much greater distances than those accessible with protostar counts. Appendices are available in electronic form at http://www.aanda.orgThe N(H) map as a FITS file is only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/577/L6

A Dual-Stimuli-Responsive Sodium-Bromine Battery with Ultrahigh Energy Density.

PubMed

Wang, Faxing; Yang, Hongliu; Zhang, Jian; Zhang, Panpan; Wang, Gang; Zhuang, Xiaodong; Cuniberti, Gianaurelio; Feng, Xinliang

2018-06-01

Stimuli-responsive energy storage devices have emerged for the fast-growing popularity of intelligent electronics. However, all previously reported stimuli-responsive energy storage devices have rather low energy densities (<250 Wh kg -1 ) and single stimuli-response, which seriously limit their application scopes in intelligent electronics. Herein, a dual-stimuli-responsive sodium-bromine (Na//Br 2 ) battery featuring ultrahigh energy density, electrochromic effect, and fast thermal response is demonstrated. Remarkably, the fabricated Na//Br 2 battery exhibits a large operating voltage of 3.3 V and an energy density up to 760 Wh kg -1 , which outperforms those for the state-of-the-art stimuli-responsive electrochemical energy storage devices. This work offers a promising approach for designing multi-stimuli-responsive and high-energy rechargeable batteries without sacrificing the electrochemical performance. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

An Experiment to Study Sporadic Sodium Layers in the Earth's Mesosphere and Lower Thermosphere

NASA Technical Reports Server (NTRS)

Swenson, Charles M.

2002-01-01

The Utah State University / Space Dynamics Lab was funded under a NASA Grant. This investigation has been part of Rockwell Universities Sudden Atom Layer Investigation (SAL). USU/SDL provided an electron density measurement instrument, the plasma frequency probe, which was launched on the vehicle 21.117 from Puerto-Rico in February of 1998. The instrument successfully measured electron density as designed and measurement techniques included in this version of the Plasma Frequency probe provided valuable insight into the electron density structures associated with sudden sodium layers in a collisional plasma. Electron density data was furnished to Rockwell University but no science meetings were held by Rockwell Data from the instrument was presented to the scientific community at the URSI General Session in 1999. A paper is in preparation for publication in Geophysical Research Letters. The following document provides a summary of the experiment and data obtained as a final report on this grant.

[Study on THz spectra and vibrational modes of benzoic acid and sodium Benzoate].

PubMed

Zheng, Zhuan-Ping; Fan, Wen-Hui; Yan, Hui; Liu, Jia; Xu, Li-Min

2013-03-01

Terahertz time-domain spectroscopy was employed to measure the terahertz absorption spectra of benzoic acid and sodium benzoate at room temperature. The origins of the measured features of benzoic acid were summarized based on previous study. Density functional theory was used to compute and analyze the molecular structure and vibrational modes of sodium benzoate in monomer. Based on the obtained results, the authors found that the THz spectral features can be used to distinguish benzoic acid and sodium benzoate totally; the essential reason for the THz spectral difference between benzoic acid and sodium benzoate is that the electrovalent bond of sodium benzoate affects the values of covalent bond lengths and bond angles, as well as the molecular interactions and arrangement in unit cell; the measured features of benzoic acid and sodium benzoate come from the collective vibrations except the peaks located at 107 cm-1 of benzoic acid and 54 cm-1 of sodium benzoate.

Differential Ablation of Cosmic Dust and Implications for the Relative Abundances of Atmospheric Metals

NASA Astrophysics Data System (ADS)

McNeil, W. J.

1997-09-01

Metals in the Earth's atmosphere are of interest and importance for several reasons. Emission lines from the sodium layer are used for wave front corrections in imaging space objects. The ionospheric metals present background contamination for remote sensing and tracking of space- born objects. Ionization during meteor showers may also interfere with communications. Although it is generally accepted that extraterrestrial material is the source of metals in the atmospheric, the relative abundances of mesospheric metals and ions present us with a conundrum. Lidar observations have consistently shown that the abundances of neutral metals in the atmospheric and the abundances of these metals in the meteoric material that falls to earth are significantly disproportionate. For example, the column density of neutral sodium is perhaps two orders of magnitude larger than that of calcium, while the abundances in meteorites are approximately equal. To complicate matters further, ion mass spectroscopy has shown that the abundances of the meteoric ions match reasonably well those in the meteorites. We present here a model that attempts to address these discrepancies. At the heart of the model is the concept of differential ablation, which suggests that more volatile metals sublimate earlier in the descent of a cosmic dust particle than do the less volatile components. The modeling is carried out comprehensively, beginning with the heating and vaporization of the dust particles. The vaporization rate is computed as a function of altitude from an ensemble of particles to give a deposition function which is then injected into a fully time-dependent kinetic code which allows for vertical diffusion and includes diurnal dependence through both the models of the major atmospheric components and through transport of the ions due to electric fields.

The tobacco mosaic virus RNA polymerase complex contains a plant protein related to the RNA-binding subunit of yeast eIF-3.

PubMed Central

Osman, T A; Buck, K W

1997-01-01

A sucrose density gradient-purified, membrane-bound tobacco mosaic virus (tomato strain L) (TMV-L) RNA polymerase containing endogenous RNA template was efficiently solubilized with sodium taurodeoxycholate. Solubilization resulted in an increase in the synthesis of positive-strand, 6.4-kb genome-length single-stranded RNA (ssRNA) and a decrease in the production of 6.4-kbp double-stranded RNA (dsRNA) to levels close to the limits of detection. The solubilized TMV-L RNA polymerase was purified by chromatography on columns of DEAE-Bio-Gel and High Q. Analysis by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and silver staining showed that purified RNA polymerase preparations consistently contained proteins with molecular masses of 183, 126, 56, 54, and 50 kDa, which were not found in equivalent material from healthy plants. Western blotting showed that the two largest of these proteins are the TMV-L-encoded 183- and 126-kDa replication proteins and that the 56-kDa protein is related to the 54.6-kDa GCD10 protein, the RNA-binding subunit of yeast eIF-3. The 126-, 183-, and 56-kDa proteins were coimmunoaffinity selected by antibodies against the TMV-L 126-kDa protein and by antibodies against the GCD10 protein. Antibody-linked polymerase assays showed that active TMV-L RNA polymerase bound to antibodies against the TMV-L 126-kDa protein and to antibodies against the GCD10 protein. Synthesis of genome-length ssRNA and dsRNA by a template-dependent, membrane-bound RNA polymerase was inhibited by antibodies against the GCD10 protein, and this inhibition was reversed by prior addition of GCD10 protein. PMID:9223501

Sodium-sulfur batteries for spacecraft energy storage

NASA Technical Reports Server (NTRS)

Dueber, R. E.

1986-01-01

Power levels for future space missions will be much higher than are presently attainable using nickel-cadmium and nickel-hydrogen batteries. Development of a high energy density rechargeable battery is essential in being able to provide these higher power levels without tremendous weight penalties. Studies conducted by both the Air Force and private industry have identified the sodium-sulfur battery as the best candidate for a next generation battery system. The advantages of the sodium-sulfur battery over the nickel-cadmium battery are discussed.

Molecular studies on di-sodium tartrate molecule

NASA Astrophysics Data System (ADS)

Divya, P.; Jayakumar, S.; George, Preethamary; Shubashree, N. S.; Ahmed. M, Anees

2015-06-01

Structural characterization is important for the development of new material. The acoustical parameters such as Free Length, Internal Pressure have been measured from ultrasonic velocity, density for di sodium tartrate an optically active molecule at different temperatures using ultrasonic interferometer of frequency (2MHZ). The ultrasonic velocity increases with increase in concentration there is an increase in solute-solvent interaction. The stability constant had been calculated. SEM with EDAX studies has been done for Di-sodium tartrate an optically active molecule.

Making Positive Electrodes For Sodium/Metal Chloride Cells

NASA Technical Reports Server (NTRS)

Bugga, Ratnakumar V.; Distefano, Salvador; Bankston, C. Perry

1992-01-01

High coulombic yields provided by sodium/metal chloride battery in which cathode formed by impregnating sintered nickel plaque with saturated solution of nickel chloride. Charge/discharge cycling of nickel chloride electrode results in very little loss of capacity. Used in spacecraft, electric land vehicles, and other applications in which high-energy-density power systems required.

Stability and Structure of Star-Shape Granules

NASA Astrophysics Data System (ADS)

Zhao, Yuchen; Bares, Jonathan; Zheng, Matthew; Dierichs, Karola; Menges, Achim; Behringer, Robert

2015-11-01

Columns are made of convex non-cohesive grains like sand collapse after being released from initial positions. On the other hand, various architectures built by concave grains can maintain stability. We explore why these structures are stable, and how stable they can be. We performed experiments by randomly pouring identical star-shape particles into hollow cylinders left on glass and a rough base, and observed stable granular columns after lifting the cylinders. Particles have six 9 mm arms, which extend symmetrically in the xyz directions. Both the probability of creating a stable column and mechanical stability aspects have been investigated. We define r as the weight fraction of particles that fall out of the column after removing confinement. r gradually increases as the column height increases, or the column diameter decreases. We also explored different experiment conditions such as vibration of columns with confinement, or large basal friction. We also consider different stability measures such as the maximum inclination angle or maximum weight a column can support. In order to understand structure leading to stability, 3D CT scan reconstructions of columns have been done and coordination number and packing density will be discussed. We acknowledge supports from W.M.Keck Foundation and Research Triangle MRSEC.

Large-Area Carbon Nanosheets Doped with Phosphorus: A High-Performance Anode Material for Sodium-Ion Batteries.

PubMed

Hou, Hongshuai; Shao, Lidong; Zhang, Yan; Zou, Guoqiang; Chen, Jun; Ji, Xiaobo

2017-01-01

Large-area phosphorus-doped carbon nanosheets (P-CNSs) are first obtained from carbon dots (CDs) through self-assembly driving from thermal treatment with Na catalysis. This is the first time to realize the conversion from 0D CDs to 2D nanosheets doped with phosphorus. The sodium storage behavior of phosphorus-doped carbon material is also investigated for the first time. As anode material for sodium-ion batteries (SIBs), P-CNSs exhibit superb performances for electrochemical storage of sodium. When cycled at 0.1 A g -1 , the P-CNSs electrode delivers a high reversible capacity of 328 mAh g -1 , even at a high current density of 20 A g -1 , a considerable capacity of 108 mAh g -1 can still be maintained. Besides, this material also shows excellent cycling stability, at a current density of 5 A g -1 , the reversible capacity can still reach 149 mAh g -1 after 5000 cycles. This work will provide significant value for the development of both carbon materials and SIBs anode materials.

High-performance sodium-organic battery by realizing four-sodium storage in disodium rhodizonate

NASA Astrophysics Data System (ADS)

Lee, Minah; Hong, Jihyun; Lopez, Jeffrey; Sun, Yongming; Feng, Dawei; Lim, Kipil; Chueh, William C.; Toney, Michael F.; Cui, Yi; Bao, Zhenan

2017-11-01

Sodium-ion batteries (SIBs) for grid-scale applications need active materials that combine a high energy density with sustainability. Given the high theoretical specific capacity 501 mAh g-1, and Earth abundance of disodium rhodizonate (Na2C6O6), it is one of the most promising cathodes for SIBs. However, substantially lower reversible capacities have been obtained compared with the theoretical value and the understanding of this discrepancy has been limited. Here, we reveal that irreversible phase transformation of Na2C6O6 during cycling is the origin of the deteriorating redox activity of Na2C6O6. The active-particle size and electrolyte conditions were identified as key factors to decrease the activation barrier of the phase transformation during desodiation. On the basis of this understanding, we achieved four-sodium storage in a Na2C6O6 electrode with a reversible capacity of 484 mAh g-1, an energy density of 726 Wh kg-1cathode, an energy efficiency above 87% and a good cycle retention.

The Role of Sodium in Tuning Product Distribution in Syngas Conversion by Rh Catalysts

DOE PAGES

Yang, Nuoya; Liu, Xinyan; Asundi, Arun S.; ...

2017-10-23

Alkali metal oxides commonly exist as impurities or promoters in syngas conversion catalysts and can significantly influence the activity and selectivity towards higher oxygenate products. In this study, we investigate the effects of sodium oxide on silica-supported Rh catalysts by experimentally introducing different amounts of sodium and monitoring the change in reactivity and CO adsorption behavior. The experimental results combined with density functional theory (DFT) calculations show that sodium selectively blocks step/defect sites on Rh surfaces, leading to reduced activity but higher C 2 oxygenate selectivity. DFT calculations also suggest that sodium present on Rh terrace sites can facilitate COmore » dissociation, potentially increasing C 2 oxygenate production. The overall activity and selectivity toward various products can be changed significantly based on the degree of site blocking by the added sodium.« less

The Role of Sodium in Tuning Product Distribution in Syngas Conversion by Rh Catalysts

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Nuoya; Liu, Xinyan; Asundi, Arun S.

Alkali metal oxides commonly exist as impurities or promoters in syngas conversion catalysts and can significantly influence the activity and selectivity towards higher oxygenate products. In this study, we investigate the effects of sodium oxide on silica-supported Rh catalysts by experimentally introducing different amounts of sodium and monitoring the change in reactivity and CO adsorption behavior. The experimental results combined with density functional theory (DFT) calculations show that sodium selectively blocks step/defect sites on Rh surfaces, leading to reduced activity but higher C 2 oxygenate selectivity. DFT calculations also suggest that sodium present on Rh terrace sites can facilitate COmore » dissociation, potentially increasing C 2 oxygenate production. The overall activity and selectivity toward various products can be changed significantly based on the degree of site blocking by the added sodium.« less

The H i-to-H{sub 2} Transition in a Turbulent Medium

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bialy, Shmuel; Sternberg, Amiel; Burkhart, Blakesley, E-mail: shmuelbi@mail.tau.ac.il

2017-07-10

We study the effect of density fluctuations induced by turbulence on the H i/H{sub 2} structure in photodissociation regions (PDRs) both analytically and numerically. We perform magnetohydrodynamic numerical simulations for both subsonic and supersonic turbulent gas and chemical H i/H{sub 2} balance calculations. We derive atomic-to-molecular density profiles and the H i column density probability density function (PDF) assuming chemical equilibrium. We find that, while the H i/H{sub 2} density profiles are strongly perturbed in turbulent gas, the mean H i column density is well approximated by the uniform-density analytic formula of Sternberg et al. The PDF width depends onmore » (a) the radiation intensity–to–mean density ratio, (b) the sonic Mach number, and (c) the turbulence decorrelation scale, or driving scale. We derive an analytic model for the H i PDF and demonstrate how our model, combined with 21 cm observations, can be used to constrain the Mach number and driving scale of turbulent gas. As an example, we apply our model to observations of H i in the Perseus molecular cloud. We show that a narrow observed H i PDF may imply small-scale decorrelation, pointing to the potential importance of subcloud-scale turbulence driving.« less

Monodisperse CNT Microspheres for High Permeability and Efficiency Flow-Through Filtration Applications.

PubMed

Copic, Davor; Maggini, Laura; De Volder, Michael

2018-03-01

Carbon nanotube (CNT)-based filters have the potential to revolutionize water treatment because of their high capacity and fast kinetics in sorption of organic, inorganic, and biological pollutants. To date, CNT filters either rely on CNTs dispersed in liquids, which are difficult to recover and cause safety concerns, or on CNT buckypaper, which offers high efficiency, but suffers from an intrinsic trade-off between filter permeability and capacity. Here, a new approach is presented that bypasses this trade-off and achieves buckypaper-like efficiency combined with filter-column-like permeability and capacity. For this, CNTs are first assembled into porous microspheres and then are packed into microfluidic column filters. These microcolumns exhibit large flow-through filtration efficiencies, while maintaining membrane permeabilities an order of magnitude larger then CNT buckypaper and specific permeabilities double that of activated carbon for similar flowrates (232 000 L m -2 h -1 bar -1 , 1.23 × 10 -12 m 2 ). Moreover, in a test to remove sodium dodecyl sulfate (SDS) from water, these microstructured CNT columns outperform activated carbon columns. This improved filtration efficiency and permeability is an important step toward a broader implementation of CNT-based filtration devices. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Dual-wavelength light-emitting diode-based ultraviolet absorption detector for nano-flow capillary liquid chromatography.

PubMed

Xie, Xiaofeng; Tolley, Luke T; Truong, Thy X; Tolley, H Dennis; Farnsworth, Paul B; Lee, Milton L

2017-11-10

The design of a miniaturized LED-based UV-absorption detector was significantly improved for on-column nanoflow LC. The detector measures approximately 27mm×24mm×10mm and weighs only 30g. Detection limits down to the nanomolar range and linearity across 3 orders of magnitude were obtained using sodium anthraquinone-2-sulfonate as a test analyte. Using two miniaturized detectors, a dual-detector system was assembled containing 255nm and 275nm LEDs with only 216nL volume between the detectors A 100μm slit was used for on-column detection with a 150μm i.d. packed capillary column. Chromatographic separation of a phenol mixture was demonstrated using the dual-detector system, with each detector producing a unique chromatogram. Less than 6% variation in the ratios of absorbances measured at the two wavelengths for specific analytes was obtained across 3 orders of magnitude concentration, which demonstrates the potential of using absorption ratio measurements for target analyte detection. The dual-detector system was used for simple, but accurate, mobile phase flow rate measurement at the exit of the column. With a flow rate range from 200 to 2000nL/min, less than 3% variation was observed. Copyright © 2017 Elsevier B.V. All rights reserved.

VALIDATION TESTING OF NEW MECHANISMS WITH OUTDOOR CHAMBER DATA, VOLUME 3: CALCULATION OF PHOTOCHEMICAL REACTION PHOTOLYSIS RATES IN THE UNC OUTDOOR CHAMBER

EPA Science Inventory

A new model is described for computing in-chamber actinic flux using site specific conditions that include time of day, air pressure, total column ozone, total column water vapor, relative humidity, aerosol type, aerosol optical density at 500 nm, and the spectral albedo of the g...

Effect of water-column pH on sediment-phosphorus release rates in Upper Klamath Lake, Oregon, 2001

USGS Publications Warehouse

Fisher, Lawrence H.; Wood, Tamara M.

2004-01-01

Sediment-phosphorus release rates as a function of pH were determined in laboratory experiments for sediment and water samples collected from Shoalwater Bay in Upper Klamath Lake, Oregon, in 2001. Aerial release rates for a stable sediment/water interface that is representative of the sediment surface area to water column volume ratio (1:3) observed in the lake and volumetric release rates for resuspended sediment events were determined at three different pH values (8.1, 9.2, 10.2). Ambient water column pH (8.1) was maintained by sparging study columns with atmospheric air. Elevation of the water column pH to 9.2 was achieved through the removal of dissolved carbon dioxide by sparging with carbon dioxide-reduced air, partially simulating water chemistry changes that occur during algal photosynthesis. Further elevation of the pH to 10.2 was achieved by the addition of sodium hydroxide, which doubled average alkalinities in the study columns from about 1 to 2 milliequivalents per liter. Upper Klamath Lake sediments collected from the lake bottom and then placed in contact with lake water, either at a stable sediment/water interface or by resuspension, exhibited an initial capacity to take up soluble reactive phosphorus (SRP) from the water column rather than release phosphorus to the water column. At a higher pH this initial uptake of phosphorus is slowed, but not stopped. This initial phase was followed by a reversal in which the sediments began to release SRP back into the water column. The release rate of phosphorus 30 to 40 days after suspension of sediments in the columns was 0.5 mg/L/day (micrograms per liter per day) at pH 8, and 0.9 mg/L/day at pH 10, indicating that the higher pH increased the rate of phosphorus release by a factor of about two. The highest determined rate of release was approximately 10% (percent) of the rate required to explain the annual internal loading to Upper Klamath Lake from the sediments as calculated from a lake-wide mass balance and observed in total phosphorus data collected at individual locations.

Accretion Makes a Splash on TW Hydrae

NASA Astrophysics Data System (ADS)

Brickhouse, N. S.

2011-12-01

The Chandra Large Program on the Classical T Tauri star TW Hydrae (489 ksec, obtained over the course of one month) brings a wealth of spectral diagnostics to the study of X-ray emission from a young star. The emission measure distribution shows two components separated by a gap (i.e. no emission measure in between). Light curves for the two components can then be constructed from the summed light curves of the appropriate individual lines. The two light curves show uncorrelated variability, with one large flare occurring only in the hot component. We associate the hotter component with the corona, since its peak temperature is ˜10 MK. Ne IX line ratio diagnostics for temperature and density indicate that the source of the cooler component is indeed the accretion shock, as originally reported by Kastner et al. (2002). The temperature and density of the accretion shock are in excellent agreement with models using mass accretion rates derived from the optical. We require a third component, which we call the "post-shock region," from line ratio diagnostics of O VII. The density derived from O VII is lower than the density derived from Ne IX, contrary to standard one-dimensional model expectations and from hydrodynamics simulations to date. The column densities derived from the two ions are also significantly different, with the column density from O VII lower than that from Ne IX. This post-shock region cannot be the settling flow expected from the cooling of the shock column, since its mass is 30 times the mass of material that passes through the shock. Instead this region is the splash of stellar atmosphere that has been hit by the accretion stream and heated by the accretion process (Brickhouse et al. 2010).

Scalable and sustainable synthesis of carbon microspheres via a purification-free strategy for sodium-ion capacitors

NASA Astrophysics Data System (ADS)

Wang, Shijie; Wang, Rutao; Zhang, Yabin; Jin, Dongdong; Zhang, Li

2018-03-01

Sodium-based energy storage receives a great deal of interest due to the virtually inexhaustible sodium reserve, while the scalable and sustainable strategies to synthesize carbon-based materials with suitable interlayer spaces and large sodium storage capacities are yet to be fully investigated. Carbon microspheres, with regular geometry, non-graphitic characteristic, and stable nature are promising candidates, yet the synthetic methods are usually complex and energy consuming. In this regard, we report a scalable purification-free strategy to synthesize carbon microspheres directly from 5 species of fresh juice. As-synthesized carbon microspheres exhibit dilated interlayer distance of 0.375 nm and facilitate Na+ uptake and release. For example, such carbon microsphere anodes have a specific capacity of 183.9 mAh g-1 at 50 mA g-1 and exhibit ultra-stability (99.0% capacity retention) after 10000 cycles. Moreover, via facile activation, highly porous carbon microsphere cathodes are fabricated and show much higher energy density at high rate than commercial activated carbon. Coupling the compelling anodes and cathodes above, novel sodium-ion capacitors show the high working potential up to 4.0 V, deliver a maximum energy density of 52.2 Wh kg-1, and exhibit an acceptable capacity retention of 85.7% after 2000 cycles.

Inferring physical properties of galaxies from their emission-line spectra

NASA Astrophysics Data System (ADS)

Ucci, G.; Ferrara, A.; Gallerani, S.; Pallottini, A.

2017-02-01

We present a new approach based on Supervised Machine Learning algorithms to infer key physical properties of galaxies (density, metallicity, column density and ionization parameter) from their emission-line spectra. We introduce a numerical code (called GAME, GAlaxy Machine learning for Emission lines) implementing this method and test it extensively. GAME delivers excellent predictive performances, especially for estimates of metallicity and column densities. We compare GAME with the most widely used diagnostics (e.g. R23, [N II] λ6584/Hα indicators) showing that it provides much better accuracy and wider applicability range. GAME is particularly suitable for use in combination with Integral Field Unit spectroscopy, both for rest-frame optical/UV nebular lines and far-infrared/sub-millimeter lines arising from photodissociation regions. Finally, GAME can also be applied to the analysis of synthetic galaxy maps built from numerical simulations.

DENSITY FRACTIONATION OF FOREST SOILS: METHODOLOGICAL QUESTIONS AND INTERPRETATION OF INCUBATION RESULTS AND TURNOVER TIME IN AN ECOSYSTEM CONTEXT

EPA Science Inventory

Soil organic matter (SOM) is often separated by physical means to simplify a complex matrix into discrete fractions. A frequent approach to isolating two or more fractions is based on differing particle densities and uses a high density liquid such as sodium polytungstate (SPT). ...

Cosmic-rays, gas, and dust in nearby anticentre clouds. II. Interstellar phase transitions and the dark neutral medium

NASA Astrophysics Data System (ADS)

Remy, Q.; Grenier, I. A.; Marshall, D. J.; Casandjian, J. M.

2018-03-01

Aim. H I 21-cm and 12CO 2.6-mm line emissions trace the atomic and molecular gas phases, respectively, but they miss most of the opaque H I and diffuse H2 present in the dark neutral medium (DNM) at the transition between the H I-bright and CO-bright regions. Jointly probing H I, CO, and DNM gas, we aim to constrain the threshold of the H I-H2 transition in visual extinction, AV, and in total hydrogen column densities, NHtot. We also aim to measure gas mass fractions in the different phases and to test their relation to cloud properties. Methods: We have used dust optical depth measurements at 353 GHz, γ-ray maps at GeV energies, and H I and CO line data to trace the gas column densities and map the DNM in nearby clouds toward the Galactic anticentre and Chamaeleon regions. We have selected a subset of 15 individual clouds, from diffuse to star-forming structures, in order to study the different phases across each cloud and to probe changes from cloud to cloud. Results: The atomic fraction of the total hydrogen column density is observed to decrease in the (0.6-1) × 1021 cm-2 range in NHtot (AV ≈ 0.4 mag) because of the formation of H2 molecules. The onset of detectable CO intensities varies by only a factor of 4 from cloud to cloud, between 0.6 × 1021 cm-2 and 2.5 × 1021 cm-2 in total gas column density. We observe larger H2 column densities than linearly inferred from the CO intensities at AV > 3 mag because of the large CO optical thickness; the additional H2 mass in this regime represents on average 20% of the CO-inferred molecular mass. In the DNM envelopes, we find that the fraction of diffuse CO-dark H2 in the molecular column densities decreases with increasing AV in a cloud. For a half molecular DNM, the fraction decreases from more than 80% at 0.4 mag to less than 20% beyond 2 mag. In mass, the DNM fraction varies with the cloud properties. Clouds with low peak CO intensities exhibit large CO-dark H2 fractions in molecular mass, in particular the diffuse clouds lying at high altitude above the Galactic plane. The mass present in the DNM envelopes appears to scale with the molecular mass seen in CO as MHDNM = 62 ± 7 MH2CO0.51 ± 0.02 across two decades in mass. Conclusions: The phase transitions in these clouds show both common trends and environmental differences. These findings will help support the theoretical modelling of H2 formation and the precise tracing of H2 in the interstellar medium.

Rocket-borne observation of singly ionized carbon 158 micron emission from the diffuse interstellar medium

NASA Astrophysics Data System (ADS)

Bock, James Joseph

1994-01-01

We report an observation of 158 micron line emission from singly ionized carbon from the diffuse interstellar medium at high galactic latitude. The integrated line intensity is measured in a 36 arcmin field-of-view along a triangular scan path in a 5 deg x 20 deg region in Ursa Major using a rocket-borne, liquid helium cooled spectrophotometer. The scan includes high latitude infrared cirrus, molecular clouds, a bright external galaxy, M82, and the HI Hole, which is a region of uniquely low neutral hydrogen column density. Emission from (CII) is observed in all regions and, in the absence of appreciable CO emission, is well correlated with neutral hydrogen column density. We observe a (CII) gas cooling rate which varies from (3.25 +/- 0.8 to 1.18 +/- 0.4) x 10-26 ergs-1 H-atom-1, in good agreement with recent observations of UV absorption lines at high galactic latitude. Regions with CO emission have enhanced (CII) line emission over that expected from the correlation with neutral hydrogen column density. The line-to-continuum ratio varies from I(CII)/lambda Ilambda = 0.002 to 0.008 in comparison with the all sky average of 0.0082 reported by FIRAS, which is heavily weighted towards the Galactic plane. The far-infrared continuum intensity, measured at 134 microns, 154 microns, and 186 microns, correlates with the 100 micron brightness measured by IRAS, and in regions excluding molecular clouds, with HI column density. The far-infrared brightness correlated with HI column density is fit by a thermal spectrum with a temperature T = 16.4 (+2.3/-1.8) K assuming an index of emissivity n = 2. The residual brightness after subtracting the emission correlated with neutral hydrogen column density yields an upper limit to the far-infrared extra-galactic background radiation of lambda Ilambda (154 microns) less than 2.6 x 10-12 W cm-2 sr-1. The observation of M82 confirms the laboratory calibration of the instrument. Unique instrumentation was developed to realize the instrument. A high sensitivity detection system consisting of stressed Ge:Ga photoconductors coupled to charge integrating amplifiers is described. We developed a compact, miniature He-4 refrigerator suitable for spaceborne operation. A silicon-gap Fabry-Perot filter, designed for use in high-throughput, compact optical systems, was developed. The performance of a far-infrared low-pass filter stack with high out-of-band rejection is reported. We tested the performance of a telescope baffle system with high-off axis rejection in a combination of ground-based and rocket-borne experiments. A submillimeter-black coating suitable for use in spaceborne telescopes is described. We report the laboratory testing of the instrument and the performance during the flight, and discuss the scientific implications of the observations.

Sodium sulfur batteries for space applications

NASA Technical Reports Server (NTRS)

Degruson, James A.

1992-01-01

In 1986, Eagle-Picher Industries was selected by the Air Force to develop sodium sulfur cells for satellite applications. Specifically, the development program was geared toward low earth orbit goals requiring high charge and/or discharge rates. A number of improvements have been made on the cell level and a transition to a complete space battery was initiated at Eagle-Picher. The results of six months of testing a 250 watt/hour sodium sulfur space battery look very promising. With over 1000 LEO cycles conducted on this first battery, the next generation battery is being designed. This next design will focus on achieving greater energy densities associated with the sodium sulfur chemistry.

Evaluating analytical approaches for estimating pelagic fish biomass using simulated fish communities

USGS Publications Warehouse

Yule, Daniel L.; Adams, Jean V.; Warner, David M.; Hrabik, Thomas R.; Kocovsky, Patrick M.; Weidel, Brian C.; Rudstam, Lars G.; Sullivan, Patrick J.

2013-01-01

Pelagic fish assessments often combine large amounts of acoustic-based fish density data and limited midwater trawl information to estimate species-specific biomass density. We compared the accuracy of five apportionment methods for estimating pelagic fish biomass density using simulated communities with known fish numbers that mimic Lakes Superior, Michigan, and Ontario, representing a range of fish community complexities. Across all apportionment methods, the error in the estimated biomass generally declined with increasing effort, but methods that accounted for community composition changes with water column depth performed best. Correlations between trawl catch and the true species composition were highest when more fish were caught, highlighting the benefits of targeted trawling in locations of high fish density. Pelagic fish surveys should incorporate geographic and water column depth stratification in the survey design, use apportionment methods that account for species-specific depth differences, target midwater trawling effort in areas of high fish density, and include at least 15 midwater trawls. With relatively basic biological information, simulations of fish communities and sampling programs can optimize effort allocation and reduce error in biomass estimates.

Insertion compounds and composites made by ball milling for advanced sodium-ion batteries

PubMed Central

Zhang, Biao; Dugas, Romain; Rousse, Gwenaelle; Rozier, Patrick; Abakumov, Artem M.; Tarascon, Jean-Marie

2016-01-01

Sodium-ion batteries have been considered as potential candidates for stationary energy storage because of the low cost and wide availability of Na sources. However, their future commercialization depends critically on control over the solid electrolyte interface formation, as well as the degree of sodiation at the positive electrode. Here we report an easily scalable ball milling approach, which relies on the use of metallic sodium, to prepare a variety of sodium-based alloys, insertion layered oxides and polyanionic compounds having sodium in excess such as the Na4V2(PO4)2F3 phase. The practical benefits of preparing sodium-enriched positive electrodes as reservoirs to compensate for sodium loss during solid electrolyte interphase formation are demonstrated by assembling full C/P′2-Na1[Fe0.5Mn0.5]O2 and C/‘Na3+xV2(PO4)2F3' sodium-ion cells that show substantial increases (>10%) in energy storage density. Our findings may offer electrode design principles for accelerating the development of the sodium-ion technology. PMID:26777573

Geopolymer lightweight bricks manufactured from fly ash and foaming agent

NASA Astrophysics Data System (ADS)

Ibrahim, Wan Mastura Wan; Hussin, Kamarudin; Abdullah, Mohd Mustafa Al Bakri; Kadir, Aeslina Abdul

2017-04-01

This paper deals with the development of lightweight geopolymer bricks by using foaming agent and fly ash. The mix parameters analysed through a laboratory experiment with fix ratio of sodium silicate/sodium hydroxide solution mass ratio 2.5, fly ash/alkaline activator solution mass ratio 2.0, foaming agent/paste mass ratio 1:2 and molarity of sodium hydroxide solution used was 12M. Different curing temperature (Room Temperature, 60, 80) and foaming agent/water mass ratio (1:10 and 1:20) were studied. Compressive strength, density analysis, and water absorption has been investigated. The results show that the foamed geopolymer bricks with a lower foam/water mass ratio (1:10)and high curing temperature (80°C) leading to a better properties. Mixtures with a low density of around 1420 kg/m3 and a compressive strength of around 10 MPa were achieved.

Development and Validation of a Rapid RP-UPLC Method for the Simultaneous Estimation of Bambuterol Hydrochloride and Montelukast Sodium from Tablets

PubMed Central

Yanamandra, R.; Vadla, C. S.; Puppala, U. M.; Patro, B.; Murthy, Y. L. N.; Parimi, A. R.

2012-01-01

A rapid, simple, sensitive and selective analytical method was developed by using reverse phase ultra performance liquid chromatographic technique for the simultaneous estimation of bambuterol hydrochloride and montelukast sodium in combined tablet dosage form. The developed method is superior in technology to conventional high performance liquid chromatography with respect to speed, resolution, solvent consumption, time, and cost of analysis. Elution time for the separation was 6 min and ultra violet detection was carried out at 210 nm. Efficient separation was achieved on BEH C18 sub-2-μm Acquity UPLC column using 0.025% (v/v) trifluoro acetic acid in water and acetonitrile as organic solvent in a linear gradient program. Resolutions between bambuterol hydrochloride and montelukast sodium were found to be more than 31. The active pharmaceutical ingredient was extracted from tablet dosage from using a mixture of methanol, acetonitrile and water as diluent. The calibration graphs were linear for bambuterol hydrochloride and montelukast sodium in the range of 6.25-37.5 μg/ml. The percentage recoveries for bambuterol hydrochloride and montelukast sodium were found to be in the range of 99.1-100.0% and 98.0-101.6%, respectively. The test solution was found to be stable for 7 days when stored in the refrigerator between 2-8°. Developed UPLC method was validated as per International Conference on Harmonization specifications for method validation. This method can be successfully employed for simultaneous estimation of bambuterol hydrochloride and montelukast sodium in bulk drugs and formulations. PMID:23325991

Soil salinity study in Northern Great Plains sodium affected soil

NASA Astrophysics Data System (ADS)

Kharel, Tulsi P.

Climate and land-use changes when combined with the marine sediments that underlay portions of the Northern Great Plains have increased the salinization and sodification risks. The objectives of this dissertation were to compare three chemical amendments (calcium chloride, sulfuric acid and gypsum) remediation strategies on water permeability and sodium (Na) transport in undisturbed soil columns and to develop a remote sensing technique to characterize salinization in South Dakota soils. Forty-eight undisturbed soil columns (30 cm x 15 cm) collected from White Lake, Redfield, and Pierpont were used to assess the chemical remediation strategies. In this study the experimental design was a completely randomized design and each treatment was replicated four times. Following the application of chemical remediation strategies, 45.2 cm of water was leached through these columns. The leachate was separated into 120- ml increments and analyzed for Na and electrical conductivity (EC). Sulfuric acid increased Na leaching, whereas gypsum and CaCl2 increased water permeability. Our results further indicate that to maintain effective water permeability, ratio between soil EC and sodium absorption ratio (SAR) should be considered. In the second study, soil samples from 0-15 cm depth in 62 x 62 m grid spacing were taken from the South Dakota Pierpont (65 ha) and Redfield (17 ha) sites. Saturated paste EC was measured on each soil sample. At each sampling points reflectance and derived indices (Landsat 5, 7, 8 images), elevation, slope and aspect (LiDAR) were extracted. Regression models based on multiple linear regression, classification and regression tree, cubist, and random forest techniques were developed and their ability to predict soil EC were compared. Results showed that: 1) Random forest method was found to be the most effective method because of its ability to capture spatially correlated variation, 2) the short wave infrared (1.5 -2.29 mum) and near infrared (0.75-0.90 mum) were very sensitive to soil salinity; 3) EC prediction model using all 3 season (spring, summer and fall) images was better on state wide validation dataset compared to individual season model. Finally, in eastern South Dakota, the model predicted that from 2008 to 2012, EC increased in 569,165 ha or 13.4% of the land seeded to corn (Zea mays L.) or soybeans (Glycine max L).

Sodium Lidar-observed Strong Inertia-gravity Wave Activities in the Mesopause Region over Fort Collins, Colorado (41 deg N, 105 deg W)

NASA Technical Reports Server (NTRS)

Li, Tao; She, C. -Y.; Liu, Han-Li; Leblanc, Thierry; McDermid, I. Stuart

2007-01-01

In December 2004, the Colorado State University sodium lidar system at Fort Collins, Colorado (41 deg N, 105 deg W), conducted an approximately 80-hour continuous campaign for the simultaneous observations of mesopause region sodium density, temperature, and zonal and meridional winds. This data set reveals the significant inertia-gravity wave activities with a period of approximately 18 hours, which are strong in both wind components since UT day 338 (second day of the campaign), and weak in temperature and sodium density. The considerable variability of wave activities was observed with both wind amplitudes growing up to approximately 40 m/s at 95-100 km in day 339 and then decreasing dramatically in day 340. We also found that the sodium density wave perturbation is correlated in phase with temperature perturbation below 90 km, and approximately 180 deg out of phase above. Applying the linear wave theory, we estimated the wave horizontal propagation direction, horizontal wavelength, and apparent horizontal phase speed to be approximately 25 deg south of west, approximately 1800 +/- 150 km, and approximately 28 +/- 2 m/s, respectively of wave intrinsic period, intrinsic phase speed, and vertical wavelength were also estimated. While the onset of enhanced inertia-gravity wave amplitude in the night of 338 was observed to be in coincidence with short-period gravity wave breaking via convective instability, the decrease of inertia-gravity wave amplitude after noon of day 339 was also observed to coincide with the development of atmospheric dynamical instability layers with downward phase progression clearly correlated with the 18-hour inertia-gravity wave, suggesting likely breaking of this inertia-gravity wave via dynamical (shear) instability.

Increasing phytoplankton-available phosphorus and inhibition of macrophyte on phytoplankton bloom.

PubMed

Dai, Yanran; Wu, Juan; Ma, Xiaohang; Zhong, Fei; Cui, Naxin; Cheng, Shuiping

2017-02-01

We assembled mesocosms to address the coherent mechanisms that an increasing phosphorus (P) concentration in water columns coupled with the phytoplankton bloom and identify the performance gap of regulating phytoplankton growth between two macrophyte species, Ceratophyllum demersum L. and Vallisneria spiralis L. Intense alkaline phosphatase activities (APA) were observed in the unplanted control, with their predominant part, phytoplankton APA (accounting for up to 44.7% of the total APA), and another large share, bacterial APA. These correspond with the large average concentration of total phosphorus (TP), total dissolved phosphorus (TDP) and soluble reactive (SRP) as well as high phytoplankton density in the water column. The consistency among P concentrations, phytoplankton density and APA, together with the positive impact of phytoplankton density on total APA revealed by the structural equation modelling (SEM), indicates that facilitated APA levels in water is an essential strategy for phytoplankton to enhance the available P. Furthermore, a positive interaction between phytoplankton APA and bacteria APA was detected, suggesting a potential collaboration between phytoplankton and bacteria to boost available P content in the water column. Both macrophyte species had a prominent performance on regulating phytoplankton proliferation. The phytoplankton density and quantum yield in C. demersum systems were all significantly lower (33.8% and 24.0%) than those in V. spiralis systems. Additionally, a greater decoupling effect of C. demersum on the relationship between P, APA, phytoplankton density, bacteria dynamic and quantum yield was revealed by SEM. These results imply that the preferred tactic of different species could lead to the performance gap. Copyright © 2016 Elsevier B.V. All rights reserved.

Test of direct and indirect effects of agrochemicals on the survival of fecal indicator bacteria.

PubMed

Staley, Zachery R; Rohr, Jason R; Harwood, Valerie J

2011-12-01

Water bodies often receive agrochemicals and animal waste carrying fecal indicator bacteria (FIB) and zoonotic pathogens, but we know little about the effects of agrochemicals on these microbes. We assessed the direct effects of the pesticides atrazine, malathion, and chlorothalonil and inorganic fertilizer on Escherichia coli and enterococcal survival in simplified microcosms held in the dark. E. coli strain composition in sediments and water column were positively correlated, but none of the agrochemicals had significant direct effects on E. coli strain composition or on densities of culturable FIBs. In a companion study, microcosms with nondisinfected pond water and sediments were exposed to or shielded from sunlight to examine the potential indirect effects of atrazine and inorganic fertilizer on E. coli. The herbicide atrazine had no effect on E. coli in dark-exposed microcosms containing natural microbial and algal communities. However, in light-exposed microcosms, atrazine significantly lowered E. coli densities in the water column and significantly increased densities in the sediment compared to controls. This effect appears to be mediated by the effects of atrazine on algae, given that atrazine significantly reduced phytoplankton, which was a positive and negative predictor of E. coli densities in the water column and sediment, respectively. These data suggest that atrazine does not directly affect the survival of FIB, rather that it indirectly alters the distribution and abundance of E. coli by altering phytoplankton and periphyton communities. These results improve our understanding of the influence of agricultural practices on FIB densities in water bodies impacted by agricultural runoff.

Test of Direct and Indirect Effects of Agrochemicals on the Survival of Fecal Indicator Bacteria▿

PubMed Central

Staley, Zachery R.; Rohr, Jason R.; Harwood, Valerie J.

2011-01-01

Water bodies often receive agrochemicals and animal waste carrying fecal indicator bacteria (FIB) and zoonotic pathogens, but we know little about the effects of agrochemicals on these microbes. We assessed the direct effects of the pesticides atrazine, malathion, and chlorothalonil and inorganic fertilizer on Escherichia coli and enterococcal survival in simplified microcosms held in the dark. E. coli strain composition in sediments and water column were positively correlated, but none of the agrochemicals had significant direct effects on E. coli strain composition or on densities of culturable FIBs. In a companion study, microcosms with nondisinfected pond water and sediments were exposed to or shielded from sunlight to examine the potential indirect effects of atrazine and inorganic fertilizer on E. coli. The herbicide atrazine had no effect on E. coli in dark-exposed microcosms containing natural microbial and algal communities. However, in light-exposed microcosms, atrazine significantly lowered E. coli densities in the water column and significantly increased densities in the sediment compared to controls. This effect appears to be mediated by the effects of atrazine on algae, given that atrazine significantly reduced phytoplankton, which was a positive and negative predictor of E. coli densities in the water column and sediment, respectively. These data suggest that atrazine does not directly affect the survival of FIB, rather that it indirectly alters the distribution and abundance of E. coli by altering phytoplankton and periphyton communities. These results improve our understanding of the influence of agricultural practices on FIB densities in water bodies impacted by agricultural runoff. PMID:22003017

The structure and statistics of interstellar turbulence

NASA Astrophysics Data System (ADS)

Kritsuk, A. G.; Ustyugov, S. D.; Norman, M. L.

2017-06-01

We explore the structure and statistics of multiphase, magnetized ISM turbulence in the local Milky Way by means of driven periodic box numerical MHD simulations. Using the higher order-accurate piecewise-parabolic method on a local stencil (PPML), we carry out a small parameter survey varying the mean magnetic field strength and density while fixing the rms velocity to observed values. We quantify numerous characteristics of the transient and steady-state turbulence, including its thermodynamics and phase structure, kinetic and magnetic energy power spectra, structure functions, and distribution functions of density, column density, pressure, and magnetic field strength. The simulations reproduce many observables of the local ISM, including molecular clouds, such as the ratio of turbulent to mean magnetic field at 100 pc scale, the mass and volume fractions of thermally stable Hi, the lognormal distribution of column densities, the mass-weighted distribution of thermal pressure, and the linewidth-size relationship for molecular clouds. Our models predict the shape of magnetic field probability density functions (PDFs), which are strongly non-Gaussian, and the relative alignment of magnetic field and density structures. Finally, our models show how the observed low rates of star formation per free-fall time are controlled by the multiphase thermodynamics and large-scale turbulence.

Excitation of the molecular gas in the nuclear region of M 82

NASA Astrophysics Data System (ADS)

Loenen, A. F.; van der Werf, P. P.; Güsten, R.; Meijerink, R.; Israel, F. P.; Requena-Torres, M. A.; García-Burillo, S.; Harris, A. I.; Klein, T.; Kramer, C.; Lord, S.; Martín-Pintado, J.; Röllig, M.; Stutzki, J.; Szczerba, R.; Weiß, A.; Philipp-May, S.; Yorke, H.; Caux, E.; Delforge, B.; Helmich, F.; Lorenzani, A.; Morris, P.; Philips, T. G.; Risacher, C.; Tielens, A. G. G. M.

2010-10-01

We present high-resolution HIFI spectroscopy of the nucleus of the archetypical starburst galaxy M 82. Six 12CO lines, 2 13CO lines and 4 fine-structure lines have been detected. Besides showing the effects of the overall velocity structure of the nuclear region, the line profiles also indicate the presence of multiple components with different optical depths, temperatures, and densities in the observing beam. The data have been interpreted using a grid of PDR models. It is found that the majority of the molecular gas is in low density (n = 103.5 cm-3) clouds, with column densities of NH = 1021.5 cm-2 and a relatively low UV radiation field (G0 = 102). The remaining gas is predominantly found in clouds with higher densities (n = 105 cm-3) and radiation fields (G0 = 102.75), but somewhat lower column densities (NH = 1021.2 cm-2). The highest J CO lines are dominated by a small (1% relative surface filling) component, with an even higher density (n = 106 cm-3) and UV field (G0 = 103.25). These results show the strength of multi-component modelling for interpretating the integrated properties of galaxies.

Effect of 25% Sodium Reduction on Sales of a Top-Selling Bread in Remote Indigenous Australian Community Stores: A Controlled Intervention Trial

PubMed Central

McMahon, Emma; Webster, Jacqui; Brimblecombe, Julie

2017-01-01

Reducing sodium in the food supply is key to achieving population salt targets, but maintaining sales is important to ensuring commercial viability and maximising clinical impact. We investigated whether 25% sodium reduction in a top-selling bread affected sales in 26 remote Indigenous community stores. After a 23-week baseline period, 11 control stores received the regular-salt bread (400 mg Na/100 g) and 15 intervention stores received the reduced-salt version (300 mg Na/100 g) for 12-weeks. Sales data were collected to examine difference between groups in change from baseline to follow-up (effect size) in sales (primary outcome) or sodium density, analysed using a mixed model. There was no significant effect on market share (−0.31%; 95% CI −0.68, 0.07; p = 0.11) or weekly dollars ($58; −149, 266; p = 0.58). Sodium density of all purchases was not significantly reduced (−8 mg Na/MJ; −18, 2; p = 0.14), but 25% reduction across all bread could significantly reduce sodium (−12; −23, −1; p = 0.03). We found 25% salt reduction in a top-selling bread did not affect sales in remote Indigenous community stores. If achieved across all breads, estimated salt intake in remote Indigenous Australian communities would be reduced by approximately 15% of the magnitude needed to achieve population salt targets, which could lead to significant health gains at the population-level. PMID:28264485

Application of steel slag coated with sodium hydroxide to enhance precipitation-coagulation for phosphorus removal.

PubMed

Park, Taejun; Ampunan, Vanvimol; Maeng, Sungkyu; Chung, Eunhyea

2017-01-01

Phosphorus removal has been studied for decades to reduce the environmental impact of phosphorus in natural waterbodies. Slag has been applied for the phosphorus removal by several mechanisms. In this study, sodium hydroxide coating was applied on the slag surface to enhance the efficiency of precipitation-coagulation process. In the batch test, it was found that the capacity of the slag to maintain high pH decreases with increasing its exposure time to the aqueous solution. In the column test, the coarse-grained coated slag showed higher phosphorus removal efficiency than the fine-grained uncoated slag. The coated slag maintained pH higher than uncoated slag and, accordingly, the removal efficiency of phosphorus was higher. Especially, when pH was less than 8, the removal efficiency decreased significantly. However, coated slag provided an excess amount of aluminum and sodium. Thus, a return process to reuse aluminum and sodium as a coagulant was introduced. The return process yields longer lifespan of slag with higher phosphorus removal and lower concentration of cations in the effluent. With the return process, the phosphorus removal efficiency was kept higher than 60% until 150 bed volumes; meanwhile, the efficiency without return process became lower than 60% at 25 bed volumes. Copyright © 2016 Elsevier Ltd. All rights reserved.

Rapid and Sensitive Reverse-phase High-performance Liquid Chromatography Method for Estimation of Ketorolac in Pharmaceuticals Using Weighted Regression

PubMed Central

Dubey, S. K.; Duddelly, S.; Jangala, H.; Saha, R. N.

2013-01-01

A reliable, rapid and sensitive isocratic reverse phase high-performance liquid chromatography method has been developed and validated for assay of ketorolac tromethamine in tablets and ophthalmic dosage forms using diclofenac sodium as an internal standard. An isocratic separation of ketorolac tromethamine was achieved on Oyster BDS (150×4.6 mm i.d., 5 μm particle size) column using mobile phase of methanol:acetonitrile:sodium dihydrogen phosphate (20 mM; pH 5.5) (50:10:40, %v/v) at a flow rate of 1.0 ml/min. The eluents were monitored at 322 nm for ketorolac and at 282 nm for diclofenac sodium with a photodiode array detector. The retention times of ketorolac and diclofenac sodium were found to be 1.9 min and 4.6 min, respectively. Response was a linear function of drug concentration in the range of 0.01-15 μg/ml (R2=0.994; linear regression model using weighing factor 1/x2) with a limit of detection and quantification of 0.002 μg/ml and 0.007 μg/ml, respectively. The % recovery and % relative standard deviation values indicated the method was accurate and precise. PMID:23901166

Column-to-column packing variation of disposable pre-packed columns for protein chromatography.

PubMed

Schweiger, Susanne; Hinterberger, Stephan; Jungbauer, Alois

2017-12-08

In the biopharmaceutical industry, pre-packed columns are the standard for process development, but they must be qualified before use in experimental studies to confirm the required performance of the packed bed. Column qualification is commonly done by pulse response experiments and depends highly on the experimental testing conditions. Additionally, the peak analysis method, the variation in the 3D packing structure of the bed, and the measurement precision of the workstation influence the outcome of qualification runs. While a full body of literature on these factors is available for HPLC columns, no comparable studies exist for preparative columns for protein chromatography. We quantified the influence of these parameters for commercially available pre-packed and self-packed columns of disposable and non-disposable design. Pulse response experiments were performed on 105 preparative chromatography columns with volumes of 0.2-20ml. The analyte acetone was studied at six different superficial velocities (30, 60, 100, 150, 250 and 500cm/h). The column-to-column packing variation between disposable pre-packed columns of different diameter-length combinations varied by 10-15%, which was acceptable for the intended use. The column-to-column variation cannot be explained by the packing density, but is interpreted as a difference in particle arrangement in the column. Since it was possible to determine differences in the column-to-column performance, we concluded that the columns were well-packed. The measurement precision of the chromatography workstation was independent of the column volume and was in a range of±0.01ml for the first peak moment and±0.007 ml 2 for the second moment. The measurement precision must be considered for small columns in the range of 2ml or less. The efficiency of disposable pre-packed columns was equal or better than that of self-packed columns. Copyright © 2017 The Author(s). Published by Elsevier B.V. All rights reserved.

Synthesis of Donor/Acceptor-Substituted Diazo Compounds in Flow and Their Application in Enantioselective Dirhodium-Catalyzed Cyclopropanation and C-H Functionalization.

PubMed

Rackl, Daniel; Yoo, Chun-Jae; Jones, Christopher W; Davies, Huw M L

2017-06-16

A tandem reaction system has been developed for the preparation of donor/acceptor-substituted diazo compounds in continuous flow coupled to dirhodium-catalyzed C-H functionalization or cyclopropanation. Hydrazones were oxidized in flow by solid-supported N-iodo-p-toluenesulfonamide potassium salt (PS-SO 2 NIK) to generate the diazo compounds, which were then purified by passing through a column of molecular sieves/sodium thiosulfate.

A Critical Examination of the Reaction of Pyridoxal 5-Phosphate with Human Hemoglobin Ao

DTIC Science & Technology

1989-01-01

sodium borohydride gives unacceptable levels of methemoglobin (i.e., > 10%). Excessive foaming and methemoglobin formation can be partially avoided using...a biochemical level . By using new advances in HPLC column technology, we could better determine hetero- geneity in the product mixture due solely to... diphosphoglycerate (2,3-DPG). 6 SFH, which had been stripped of 2,3-DPG, was deoxygenated with nitrogen and treated with a solution of PLP in Tris

Approximate transient and long time limit solutions for the band broadening induced by the thin sidewall-layer in liquid chromatography columns.

PubMed

Broeckhoven, Ken; Desmet, Gert

2007-11-16

Using a combination of both analytical and numerical techniques, approximate analytical expressions have been established for the transient and long time limit band broadening, originating from the presence of a thin disturbed sidewall layer in liquid chromatography columns, including packed, monolithic as well as microfabricated columns. The established expressions can be used to compare the importance of a thin disturbed sidewall layer with that of other radial heterogeneity effects (such as transcolumn packing density variations due to the relief of packing stresses). The expressions are independent of the actual velocity profile inside the layer as long as the disturbed sidewall layer occupies less than 2.5% of the column width.

Gas-solid fluidized bed reactors: Scale-up, flow regimes identification and hydrodynamics

NASA Astrophysics Data System (ADS)

Zaid, Faraj Muftah

This research studied the scale-up, flow regimes identification and hydrodynamics of fluidized beds using 6-inch and 18- inch diameter columns and different particles. One of the objectives was to advance the scale-up of gas-solid fluidized bed reactors by developing a new mechanistic methodology for hydrodynamic similarity based on matching the radial or diameter profile of gas phase holdup, since gas dynamics dictate the hydrodynamics of these reactors. This has been successfully achieved. However, the literature reported scale-up methodology based on matching selected dimensionless groups was examined and it was found that it was not easy to match the dimensionless groups and hence, there was some deviation in the hydrodynamics of the studied two different fluidized beds. A new technique based on gamma ray densitometry (GRD) was successfully developed and utilized to on-line monitor the implementation of scale-up, to identify the flow regime, and to measure the radial or diameter profiles of gas and solids holdups. CFD has been demonstrated as a valuable tool to enable the implementation of the newly developed scale-up methodology based on finding the conditions that provide similar or closer radial profile or cross sectional distribution of the gas holdup. As gas velocity increases, solids holdup in the center region of the column decreases in the fully developed region of both 6 inch and 18 inch diameter columns. Solids holdup increased with the increase in the particles size and density. Upflowing particles velocity increased with the gas velocity and became steeper at high superficial gas velocity at all axial heights where the center line velocity became higher than that in the wall region. Smaller particles size and lower density gave larger upflowing particles velocity. Minimum fluidization velocity and transition velocity from bubbly to churn turbulent flow regimes were found to be lower in 18 inch diameter column compared to those obtained in 6 inch diameter column. Also the absolute fluctuation of upflowing particles velocity multiplied by solids holdups vś 3ś as one of the terms for solids mass flux estimation was found to be larger in 18-inch diameter column than that in 6-inch diameter column using same particles size and density.

Removal of cadmium (II) from simulated wastewater by ion flotation technique

PubMed Central

2013-01-01

A separation technique which has recently received a sharp increase in research activities is “ion flotation”. This technique has four important advantages for treating wastewaters: low energy consumption, small space requirements, small volume of sludge and acting selectively. The present study aims to optimize parameters of ion flotation for cadmium removal in simulated wastewater at laboratory scale. It was obtained on the reaction between Cd2+ and sodium dodecylesulfate (SDS) collector followed by flotation with ethanol as frother. Test solution was prepared by combining the required amount of cadmium ion, SDS and necessary frother or sodium sulfate solution. All experiments were carried out in a flotation column at laboratory temperature (27°C), adjusted pH = 4 and 120 minutes. The different parameters (namely: flow rate, cadmium, SDS and frother concentrations and ionic strength) influencing the flotation process were examined. The best removal efficiency obtained at a collector-metal ratio of 3:1 in 60 min with flow rate of 150 mL/min was 84%. The maximum cadmium removal was 92.1% where ethanol was introduced at a concentration 0.4% to flotation column with above conditions. The obtained results were promising, as both cadmium and collector were effectively removed from wastewater. Hence, the application of ion flotation for metal ions removal from effluents seems to be efficient. PMID:23388386

Controlled-release Hydrogen Peroxide for On-site Treatment of Organic Pollutants in Urban Storm Runoff

NASA Astrophysics Data System (ADS)

Lee, E.; Sun, S.; Kim, Y.

2011-12-01

Nonpoint source (NPS) pollutants are the remaining cause of the environment problems, significantly impairing the hydrologic and biologic function of urban water systems and human health. Managing the NPS loads to urban aquatic systems remains a challenge because of ubiquitous contaminant sources and large pollutants loads in the first flush. Best management practices (BMPs) exist for reducing the NPS pollutants in urban storm waters, but the remedial efficiencies of these passive schemes are unpredictable. This study aims to develop a controlled-release system as part of an in situ chemical oxidation scheme designed for on-site treatment of organic pollutants in urban runoff. Controlled-release hydrogen peroxide (CR-HP) solids were manufactured by dispersing fine sodium percarbonate granules in paraffin wax matrices. Release kinetics and treatment efficiencies of CR-HP for BTEX and MTBE were investigated through a series of column tests. Release data indicated that the CR-HP could continually release hydrogen peroxide (H2O2) in flowing water at controlled rates over 276-1756 days, and the release rates could be adjusted by changing the mixing ratios of sodium percarbonate and wax matrices. Additional column tests and model calculations demonstrated that CR-HP/UV systems can provide low-cost, target-specific, and persistent source of oxidants for efficient treatment of organic compounds in urban storm runoff.

21st Century Locomotive Technology: Quarterly Technical Status Report 28

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lembit Salasoo; Ramu Chandra

2010-02-19

Thermal testing of a subscale locomotive sodium battery module was initiated.to validate thermal models. The hybrid trip optimizer problem was formulated. As outcomes of this project, GE has proceeded to commercialize trip optimizer technology, and has initiated work on a state-of-the-art battery manufacturing plant for high energy density, sodium-based batteries.

Pooled results from five validation studies of dietary self-report instruments using recovery biomarkers for potassium and sodium intake

USDA-ARS?s Scientific Manuscript database

We have pooled data from five large validation studies of dietary self-report instruments that used recovery biomarkers as referents to assess food frequency questionnaires (FFQs) and 24-hour recalls. We reported on total potassium and sodium intakes, their densities, and their ratio. Results were...

Solid-state sodium cells - An alternative to lithium cells?

NASA Astrophysics Data System (ADS)

West, K.; Zachau-Christiansen, B.; Jacobsen, T.; Skaarup, S.

1989-05-01

The cycling properties of laboratory cells based on the insertion of sodium into vanadium oxides using polymer electrolyte at 80 C are reported. In the best system: Na/PEO, NaClO4/V2O5 (modified), C, high reversibility, and an energy density comparable with the Li/TiS2 system have been obtained.

Stability-indicating HPLC-DAD methods for determination of two binary mixtures: Rabeprazole sodium-mosapride citrate and rabeprazole sodium-itopride hydrochloride.

PubMed

El-Fatatry, Hamed M; Mabrouk, Mokhtar M; Hewala, Ismail I; Emam, Ehab H

2014-08-01

Two selective stability-indicating HPLC methods are described for determination of rabeprazole sodium (RZ)-mosapride citrate (MR) and RZ-itopride hydrochloride (IO) mixtures in the presence of their ICH-stress formed degradation products. Separations were achieved on X-Bridge C18 column using two mobile phases: the first for RZ-MR mixture consisted of acetonitrile: 0.025 M KH 2 PO 4 solution: TEA (30:69:1 v/v; pH 7.0); the second for RZ-IO mixture was at ratio of 25:74:1 (v/v; pH 9.25). The detection wavelength was 283 nm. The two methods were validated and validation acceptance criteria were met in all cases. Peak purity testing using contrast angle theory, relative absorbance and log  A versus the wavelengths plots were presented. The % recoveries of the intact drugs were between 99.1% and 102.2% with RSD% values less than 1.6%. Application of the proposed HPLC methods indicated that the methods could be adopted to follow the stability of their formulations.

Biosynthesis of Mustard Oil Glucosides: Sodium Phenylacetothiohydroximate and Desulfobenzylglucosinolate, Precursors of Benzylglucosinolate in Tropaeolum majus1

PubMed Central

Underhill, L. E. W.; Wetter, L. R.

1969-01-01

The biosynthesis of the mustard oil glucoside, benzylglucosinolate, was studied in Tropaeolum majus L. A number of labeled compounds were administered to plant shoots and the incorporation of tracer into benzylglucosinolate, isolated as the crystalline tetramethyl-ammonium salt, was measured. In order of decreasing efficiency of conversion into benzyl-glucosinolate the compounds fed were S-(β-d-glucopyranosyl)phenylacetothiohydroximic acid (desulfobenzylglucosinolate), sodium phenylacetothiohydroximate, dl-phenylalanine, d-glucose, and sodium-d-1-glucopyranosyl mercaptide (1-thioglucose). The results are consistent with the hypothesis that the thioglucosyl group of benzylglucosinolate is derived by glucosylation of phenylacetothiohydroximate and not from 1-thioglucose. The results also suggest that benzylglucosinolate is formed by sulfation of desulfobenzylglucosinolate as the final step in its biosynthesis. A method for the isolation of a number of glucosinolates (mustard oil glucosides) is described which utilizes anion exchange chromatography on diethylaminoethyl (DEAE) cellulose. Potassium allylglucosinolate, tetramethylammonium benzylglucosinolate, potassium 2-hydroxy-2-phenylethylglucosinolate and potassium 2-phenylethylglucosinolate were obtained on recrystallization of the glucosinolate fraction eluted from the column. PMID:16657104

Designing solid-liquid interphases for sodium batteries.

PubMed

Choudhury, Snehashis; Wei, Shuya; Ozhabes, Yalcin; Gunceler, Deniz; Zachman, Michael J; Tu, Zhengyuan; Shin, Jung Hwan; Nath, Pooja; Agrawal, Akanksha; Kourkoutis, Lena F; Arias, Tomas A; Archer, Lynden A

2017-10-12

Secondary batteries based on earth-abundant sodium metal anodes are desirable for both stationary and portable electrical energy storage. Room-temperature sodium metal batteries are impractical today because morphological instability during recharge drives rough, dendritic electrodeposition. Chemical instability of liquid electrolytes also leads to premature cell failure as a result of parasitic reactions with the anode. Here we use joint density-functional theoretical analysis to show that the surface diffusion barrier for sodium ion transport is a sensitive function of the chemistry of solid-electrolyte interphase. In particular, we find that a sodium bromide interphase presents an exceptionally low energy barrier to ion transport, comparable to that of metallic magnesium. We evaluate this prediction by means of electrochemical measurements and direct visualization studies. These experiments reveal an approximately three-fold reduction in activation energy for ion transport at a sodium bromide interphase. Direct visualization of sodium electrodeposition confirms large improvements in stability of sodium deposition at sodium bromide-rich interphases.The chemistry at the interface between electrolyte and electrode plays a critical role in determining battery performance. Here, the authors show that a NaBr enriched solid-electrolyte interphase can lower the surface diffusion barrier for sodium ions, enabling stable electrodeposition.

Occurrence of turbulent flow conditions in supercritical fluid chromatography.

PubMed

De Pauw, Ruben; Choikhet, Konstantin; Desmet, Gert; Broeckhoven, Ken

2014-09-26

Having similar densities as liquids but with viscosities up to 20 times lower (higher diffusion coefficients), supercritical CO2 is the ideal (co-)solvent for fast and/or highly efficient separations without mass-transfer limitations or excessive column pressure drops. Whereas in liquid chromatography the flow remains laminar in both the packed bed and tubing, except in extreme cases (e.g. in a 75 μm tubing, pure acetonitrile at 5 ml/min), a supercritical fluid can experience a transition from laminar to turbulent flow in more typical operation modes. Due to the significant lower viscosity, this transition for example already occurs at 1.3 ml/min for neat CO2 when using connection tubing with an ID of 127 μm. By calculating the Darcy friction factor, which can be plotted versus the Reynolds number in a so-called Moody chart, typically used in fluid dynamics, higher values are found for stainless steel than PEEK tubing, in agreement with their expected higher surface roughness. As a result turbulent effects are more pronounced when using stainless steel tubing. The higher than expected extra-column pressure drop limits the kinetic performance of supercritical fluid chromatography and complicates the optimization of tubing ID, which is based on a trade-off between extra-column band broadening and pressure drop. One of the most important practical consequences is the non-linear increase in extra-column pressure drop over the tubing downstream of the column which leads to an unexpected increase in average column pressure and mobile phase density, and thus decrease in retention. For close eluting components with a significantly different dependence of retention on density, the selectivity can significantly be affected by this increase in average pressure. In addition, the occurrence of turbulent flow is also observed in the detector cell and connection tubing. This results in a noise-increase by a factor of four when going from laminar to turbulent flow (e.g. going from 0.5 to 2.5 ml/min for neat CO2). Copyright © 2014 Elsevier B.V. All rights reserved.

The Einstein objective grating spectrometer survey of galactic binary X-ray sources

NASA Technical Reports Server (NTRS)

Vrtilek, S. D.; Mcclintock, J. E.; Seward, F. D.; Kahn, S. M.; Wargelin, B. J.

1991-01-01

The results of observations of 22 bright Galactic X-ray point sources are presented, and the most reliable measurements to date of X-ray column densities to these sources are derived. The results are consistent with the idea that some of the objects have a component of column density intrinsic to the source in addition to an interstellar component. The K-edge absorption due to oxygen is clearly detected in 10 of the sources and the Fe L and Ne K edges are detected in a few. The spectra probably reflect emission originating in a collisionally excited region combined with emission from a photoionized region excited directly by the central source.

Size and DNA distributions of electrophoretically separated cultured human kidney cells

NASA Technical Reports Server (NTRS)

Kunze, M. E.; Plank, L. D.; Todd, P. W.

1985-01-01

Electrophoretic purification of purifying cultured cells according to function presumes that the size of cycle phase of a cell is not an overriding determinant of its electrophoretic velocity in an electrophoretic separator. The size distributions and DNA distributions of fractions of cells purified by density gradient electrophoresis were determined. No systematic dependence of electrophoretic migration upward in a density gradient column upon either size or DNA content were found. It was found that human leukemia cell populations, which are more uniform function and found in all phases of the cell cycle during exponential growth, separated on a vertical sensity gradient electrophoresis column according to their size, which is shown to be strictly cell cycle dependent.

X-ray wind tomography of IGR J17252-3616

NASA Astrophysics Data System (ADS)

Manousakis, Antonios; Walter, Roland

IGR J17252-3616 is an heavily absorbed and eclipsing High Mass X-ray Binary with an ab-sorbing hydrogen column density >1023 cm-2 . We have observed it with XMM-Newton to understand the geometry of the absorbing material. Observations were scheduled in order to cover as many orbital phases as possible. Timing analysis is constraining the orbital solution and the physical parameters of the system. Spectral analysis reveals remarkable variations of the absorbing column density and of the Iron Kα fluorescence line around the eclipse. These variations allow to map the geometry of the absorbing and reflection material. Very large accretion structures could be imaged for the first time.

THE GAS/DUST RATIO OF CIRCUMSTELLAR DISKS: TESTING MODELS OF PLANETESIMAL FORMATION

DOE Office of Scientific and Technical Information (OSTI.GOV)

Horne, David; Gibb, Erika; Rettig, Terrence W.

2012-07-20

We present high-resolution, near-infrared NIRSPEC observations of CO absorption toward six class II T Tauri stars: AA Tau, DG Tau, IQ Tau, RY Tau, CW Tau, and Haro 6-5b. {sup 12}CO overtone absorption lines originating from the circumstellar disk of each object were used to calculate line-of-sight gas column densities toward each source. We measured the gas/dust ratio as a function of disk inclination, utilizing measured visual extinctions and inclinations for each star. The majority of our sources show further evidence for a correlation between the gas/dust column density ratio and disk inclination similar to that found by Rettig etmore » al.« less

An effective method to screen sodium-based layered materials for sodium ion batteries

NASA Astrophysics Data System (ADS)

Zhang, Xu; Zhang, Zihe; Yao, Sai; Chen, An; Zhao, Xudong; Zhou, Zhen

2018-03-01

Due to the high cost and insufficient resource of lithium, sodium-ion batteries are widely investigated for large-scale applications. Typically, insertion-type materials possess better cyclic stability than alloy-type and conversion-type ones. Therefore, in this work, we proposed a facile and effective method to screen sodium-based layered materials based on Materials Project database as potential candidate insertion-type materials for sodium ion batteries. The obtained Na-based layered materials contains 38 kinds of space group, which reveals that the credibility of our screening approach would not be affected by the space group. Then, some important indexes of the representative materials, including the average voltage, volume change and sodium ion mobility, were further studied by means of density functional theory computations. Some materials with extremely low volume changes and Na diffusion barriers are promising candidates for sodium ion batteries. We believe that our classification algorithm could also be used to search for other alkali and multivalent ion-based layered materials, to accelerate the development of battery materials.

Mesospheric sodium over Gadanki during Geminid meteor shower 2007

NASA Astrophysics Data System (ADS)

Lokanadham, B.; Rakesh Chandra, N.; Bhaskara Rao, S. Vijaya; Raghunath, K.; Yellaiah, G.

Resonance LIDAR system at Gadanki has been used for observing the mesospheric sodium during the night of 12-13 Dec 2007 when the peak activity of Geminid meteor shower occurred. Geminid meteor shower is observed along with the co-located MST radar in the altitude range 80-110 km. Sodium density profiles have been obtained with a vertical resolution of 300 m and a temporal resolution of 120 s with sodium resonance scattering LIDAR system. The sodium layers were found to exist in the altitude range 90-100 km. The enhanced Geminid meteor rates were recorded with the co-located MST radar in the same altitude range. The sodium concentration in the atmospheric altitude of ~93 km is estimated to be 2000 per cc where the meteoric concentration of Geminid is maximum and reduced to around 800 on the non activity of Geminid. These observations showed that the sodium levels in the E-region are found to be increasing during meteor shower nights at least by a factor of two.

Synthesis and characterization of carbon microsphere for extinguishing sodium fire

NASA Astrophysics Data System (ADS)

Snehalatha, V.; Ponraju, D.; Nashine, B. K.; Chellapandi, P.

2013-06-01

In Sodium cooled Fast breeder Reactors (SFRs), accidental leakage of liquid sodium leads to sodium fire. Carbon microsphere is a promising and novel extinguishant for sodium fire since it possesses high thermal conductivity, chemical inertness and excellent flow characteristics. Low density Carbon microsphere (CMS) with high thermal stability was successfully synthesized from functionalized styrene divinyl benzene copolymer by carbonization under inert atmosphere. Protocol for stepwise carbonization was developed by optimizing heating rate and time of heating. The synthesized CMS was characterized by Densimeter, Scanning Electron Microscope (SEM), Fourier Transfer Infra-Red spectroscopy (FTIR), Thermogravimetry (TG), X-ray Diffraction (XRD) and RAMAN spectroscopy. CMS thus obtained was spherical in shape having diameters ranging between 60 to 80μm with narrow size distribution. The smooth surface of CMS ensures its free flow characteristics. The yield of carbonization process was about 38%. The performance of CMS was tested on small scale sodium. This paper describes the development of carbon microsphere for extinguishing sodium fire and its characteristics.

Foam capacity and stability of Sodium Dodecyl Sulfate (SDS) on the presence of contaminant coffee and Cd ions in solution

NASA Astrophysics Data System (ADS)

Haryanto, B.; Chang, C. H.; Kuo, A. T.; Siswarni, M. Z.; Sinaga, T. M. A.

2018-02-01

In this study, the effect of the coffee colloidal particle and Cd ion contaminant on the foam capacity and stability of sodium dodecyl sulfate (SDS) solution was investigated. The foam was generated by using a foam generator. The foam capacity of SDS was first evaluated at different concentrations. After the foam capacity reaching a constant value, the foam stability was then measured by flowing to a column. The results showed that the presence the coffee colloidal particles or Cd ions in the solution would decrease the foam capacity and stability of SDS. In addition, the decreased foam capacity and stability was more pronounced in the presence of coffee colloidal particles than Cd ions. The colloidal particles may have stronger interaction with SDS and thus reduce the formation of the foam.

Electromigration induced high fraction of compound formation in SnAgCu flip chip solder joints with copper column

NASA Astrophysics Data System (ADS)

Xu, Luhua; Han, Jung-Kyu; Liang, Jarrett Jun; Tu, K. N.; Lai, Yi-Shao

2008-06-01

To overcome the effect of current crowding on electromigration-induced pancake-type void formation in flip chip solder joints, two types of Cu column in 90μm flip chip SnAgCu solder joints have been studied. They were (1) the solder contacts the Cu column at bottom and side walls and (2) the solder wets only the bottom surface of the copper column. With a current density of 1.6×104A/cm2 at 135°C, no failure was detected after 1290h. However, the resistance increased by about 10% due to the formation of a large fraction of intermetallic compounds. We found that electromigration has accelerated the consumption rate of copper column and converted almost the entire solder joint into intermetallic compound. Mechanically, drop impact test indicates a brittle fracture failure in the intermetallic. The electromigration critical product for the intermetallic is discussed.

Density Functional Study for Chemical Reaction between Cr and Fe with Sodium Diethyldithiocarbamate (NaDDC)

NASA Astrophysics Data System (ADS)

Setiyanto, Henry; Muhida, Rifki; Kishi, Tomoya; Rahman, Md. Mahmudur; Dipojono, Hermawan K.; Diño, Wilson A.; Matsumoto, Shigeno; Kasai, Hideaki

Analytical chemistry in the perspective of ab initio molecular orbital calculation is introduced by investigating the chemical reaction between transition metals Cr and Fe with sodium diethyldithiocarbamate (NaDDC), a complexing agent to detect and extract Cr in human blood sample. Using density functional theory—based calculations, we determine the stable structure of the Cr-DDC and Fe-DDC complexes and obtain its dissociation energies. We found dissociation energy values of -3.24 and -2.67 eV for Cr and Fe complexes, respectively; and hence the formation of the former complex is more favorable than the formation of the latter.

In-Situ-Activated N-Doped Mesoporous Carbon from a Protic Salt and Its Performance in Supercapacitors.

PubMed

Mendes, Tiago C; Xiao, Changlong; Zhou, Fengling; Li, Haitao; Knowles, Gregory P; Hilder, Matthias; Somers, Anthony; Howlett, Patrick C; MacFarlane, Douglas R

2016-12-28

Protic salts have been recently recognized to be an excellent carbon source to obtain highly ordered N-doped carbon without the need of tedious and time-consuming preparation steps that are usually involved in traditional polymer-based precursors. Herein, we report a direct co-pyrolysis of an easily synthesized protic salt (benzimidazolium triflate) with calcium and sodium citrate at 850 °C to obtain N-doped mesoporous carbons from a single calcination procedure. It was found that sodium citrate plays a role in the final carbon porosity and acts as an in situ activator. This results in a large surface area as high as 1738 m 2 /g with a homogeneous pore size distribution and a moderate nitrogen doping level of 3.1%. X-ray photoelectron spectroscopy (XPS) measurements revealed that graphitic and pyridinic groups are the main nitrogen species present in the material, and their content depends on the amount of sodium citrate used during pyrolysis. Transmission electron microscopy (TEM) investigation showed that sodium citrate assists the formation of graphitic domains and many carbon nanosheets were observed. When applied as supercapacitor electrodes, a specific capacitance of 111 F/g in organic electrolyte was obtained and an excellent capacitance retention of 85.9% was observed at a current density of 10 A/g. At an operating voltage of 3.0 V, the device provided a maximum energy density of 35 W h/kg and a maximum power density of 12 kW/kg.

Physiochemical properties and reproducibility of air-based sodium tetradecyl sulphate foam using the Tessari method.

PubMed

Watkins, Mike R; Oliver, Richard J

2017-07-01

Objectives The objectives were to examine the density, bubble size distribution and durability of sodium tetradecyl sulphate foam and the consistency of production of foam by a number of different operators using the Tessari method. Methods 1% and 3% sodium tetradecyl sulphate sclerosant foam was produced by an experienced operator and a group of inexperienced operators using either a 1:3 or 1:4 liquid:air ratio and the Tessari method. The foam density, bubble size distribution and foam durability were measured on freshly prepared foam from each operator. Results The foam density measurements were similar for each of the 1:3 preparations and for each of the 1:4 preparations but not affected by the sclerosant concentration. The bubble size for all preparations were very small immediately after preparation but progressively coalesced to become a micro-foam (<250 µm) after the first 30 s up until 2 min. Both the 1% and 3% solution foams developed liquid more rapidly when made in a 1:3 ratio (37 s) than in a 1:4 ratio (45 s) but all combinations took similar times to reach 0.4 ml liquid formation. For all the experiments, there was no statistical significant difference between operators. Conclusions The Tessari method of foam production for sodium tetradecyl sulphate sclerosant is consistent and reproducible even when made by inexperienced operators. The best quality foam with micro bubbles should be used within the first minute after production.

An upper limit on interstellar C IV in the spectrum of gamma-2 Velorum

NASA Technical Reports Server (NTRS)

Lengyel-Frey, D.; Stecher, T. P.; West, D. K.

1975-01-01

An upper limit on the column density of C IV along the line of sight to gamma-2 Vel is derived from upper limits placed on the equivalent widths of the interstellar C IV doublet with rest wavelengths at 1548.20 A and 1550.77 A. A lower limit of 250,000 K is calculated for the electron temperature of O VI emitting regions by combining the C IV results with a measurement of the column density of interstellar O VI for the same star and using calculations for the relative ionization of some abundant elements as a function of electron temperature in a low-density plasma. Since gamma-2 Vel is in the central part of the Gum Nebula, the high temperature suggested by these results is shown to support the idea that a high-temperature phase of the interstellar medium, possibly maintained by supernova explosions, may exist.-

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

This volume contains the interim change notice for physical testing. Covered are: properties of solutions, slurries, and sludges; rheological measurement with cone/plate viscometer; % solids determination; particle size distribution by laser scanning; penetration resistance of radioactive waste; operation of differential scanning calorimeter, thermogravimetric analyzer, and high temperature DTA and DSC; sodium rod for sodium bonded fuel; filling SP-100 fuel capsules; sodium filling of BEATRIX-II type capsules; removal of alkali metals with ammonia; specific gravity of highly radioactive solutions; bulk density of radioactive granular solids; purification of Li by hot gettering/filtration; and Li filling of MOTA capsules.

Characterisation of RPLC columns packed with porous sub-2 microm particles.

PubMed

Petersson, Patrik; Euerby, Melvin R

2007-08-01

Eight commercially available sub-2 microm octadecyl silane columns (C18 columns) have been characterised by the Tanaka protocol. The columns can be grouped into two groups that display large differences in selectivity and peak shape due to differences in hydrophobicity, degree of surface coverage and silanol activity. Measurements of particle size distributions were made using automated microscopy and electrical sensing zone measurements. Only a weak correlation could be found between efficiency and particle size. Large differences in column backpressure were observed. These differences are not related to particle size distribution. A more likely explanation is differences in packing density. In order to take full advantage of 100-150 mm columns packed with sub-2 microm particles, it is often necessary to employ not only an elevated pressure but also an elevated temperature. A comparison between columns packed with sub-2, 3 and 5 microm versions of the same packing indicates potential method transferability problems for several of the columns due to selectivity differences. Currently, the best alternative for fast high-resolution LC is the use of sub-2 microm particles in combination with elevated pressure and temperature. However, as shown in this study additional efforts are needed to improve transferability as well as column performance.

Density fractionation of forest soils: methodological questions and interpretation of incubation results and turnover time in an ecosystem context

Treesearch

Susan E. Crow; Christopher W. Swanston; Kate Lajtha; J. Renee Brooks; Heath Keirstead

2007-01-01

Soil organic matter (SOM) is often separated by physical means to simplify a complex matrix into discrete fractions. A frequent approach to isolating two or more fractions is based on differing particle densities and uses a high density liquid such as sodium polytungstate (SPT). Soil density fractions are often interpreted as organic matter pools with different carbon...

On the Effect of Sodium Chloride and Sodium Sulfate on Cold Denaturation

PubMed Central

Pica, Andrea; Graziano, Giuseppe

2015-01-01

Both sodium chloride and sodium sulfate are able to stabilize yeast frataxin, causing an overall increase of its thermodynamic stability curve, with a decrease in the cold denaturation temperature and an increase in the hot denaturation one. The influence of low concentrations of these two salts on yeast frataxin stability can be assessed by the application of a theoretical model based on scaled particle theory. First developed to figure out the mechanism underlying cold denaturation in water, this model is able to predict the stabilization of globular proteins provided by these two salts. The densities of the salt solutions and their temperature dependence play a fundamental role. PMID:26197394

Zinc naphthalenedicarboxylate coordination complex: A promising anode material for lithium and sodium-ion batteries with good cycling stability.

PubMed

Fei, Hailong; Feng, Wenjing; Xu, Tan

2017-02-15

It is important to discover new, cheap and environmental friendly electrode materials with high capacity and good cycling stability for lithium and sodium-ion batteries. Zinc 1,4-naphthalenedicarboxylate was firstly found to be stable anode materials for lithium and sodium-ion batteries. The discharge capacity can be up to 468.9mAhg -1 after 100 cycles at a current density of 100mAg -1 for lithium-ion batteries, while the second discharge capacity of 320.7mAhg -1 was achieved as anode materials for sodium-ion batteries. A possible electrochemical reaction mechanism was discussed. Copyright © 2016 Elsevier Inc. All rights reserved.

First measurement of H I 21 cm emission from a GRB host galaxy indicates a post-merger system

NASA Astrophysics Data System (ADS)

Arabsalmani, Maryam; Roychowdhury, Sambit; Zwaan, Martin A.; Kanekar, Nissim; Michałowski, Michał J.

2015-11-01

We report the detection and mapping of atomic hydrogen in H I 21 cm emission from ESO 184-G82, the host galaxy of the gamma-ray burst 980425. This is the first instance where H I in emission has been detected from a galaxy hosting a gamma-ray burst (GRB). ESO 184-G82 is an isolated galaxy and contains a Wolf-Rayet region close to the location of the GRB and the associated supernova, SN 1998bw. This is one of the most luminous H II regions identified in the local Universe, with a very high inferred density of star formation. The H I 21 cm observations reveal a high H I mass for the galaxy, twice as large as the stellar mass. The spatial and velocity distribution of the H I 21 cm emission reveals a disturbed rotating gas disc, which suggests that the galaxy has undergone a recent minor merger that disrupted its rotation. We find that the Wolf-Rayet region and the GRB are both located in the highest H I column density region of the galaxy. We speculate that the merger event has resulted in shock compression of the gas, triggering extreme star formation activity, and resulting in the formation of both the Wolf-Rayet region and the GRB. The high H I column density environment of the GRB is consistent with the high H I column densities seen in absorption in the host galaxies of high-redshift GRBs.

Numerical Simulation using VolcFlow for Pyroclastic Density Currents by Explosive Eruption of Mt. Baekdu, Korea

NASA Astrophysics Data System (ADS)

Yun, S. H.; Chang, C.

2015-12-01

It is the numerical simulation using a VolcFlow model to determine the runout range of pyroclastic density currents where an eruption column had been formed by the explosive Plinian eruption and the collapse of the column had caused to occur on Mt. Baekdu. We assumed that the most realistic way for the simulation of a sustained volcanic column is to modify the topography with a cone above the crater to follow expert advice from Dr. Karim Kelfoun, the developer of VolcFlow. Then we set the radius and height of the cone, the volume of pyroclastic flow, and the duration and simulation time accoding to the volcanic explosivity index (VEI). Also we set the yield stress as 5,000 Pa, 10,000 Pa, 15,000 Pa, the basal friction angle as 3°, 5°, 10°, respectively. As the simulation results, the longest runout range was 2.3 km, 9.1 km, 14.4 km, 18.6 km, 23.4 km from VEI 3 to VEI 7, respectively. It can be used as a very important material to predict the impact range of pyroclastic density currents and to minimize human and material damages caused by pyroclastic density currents derived from the future explosive eruption of Mt. Baekdu. This research was supported by a grant 'Development of Advanced Volcanic Disaster Response System considering Potential Volcanic Risk around Korea' [MPSS-NH-2015-81] from the Natural Hazard Mitigation Research Group, National Emergency Management Agency of Korea.

Physical properties of CO-dark molecular gas traced by C+

NASA Astrophysics Data System (ADS)

Tang, Ningyu; Li, Di; Heiles, Carl; Wang, Shen; Pan, Zhichen; Wang, Jun-Jie

2016-09-01

Context. Neither Hi nor CO emission can reveal a significant quantity of so-called dark gas in the interstellar medium (ISM). It is considered that CO-dark molecular gas (DMG), the molecular gas with no or weak CO emission, dominates dark gas. Determination of physical properties of DMG is critical for understanding ISM evolution. Previous studies of DMG in the Galactic plane are based on assumptions of excitation temperature and volume density. Independent measurements of temperature and volume density are necessary. Aims: We intend to characterize physical properties of DMG in the Galactic plane based on C+ data from the Herschel open time key program, namely Galactic Observations of Terahertz C+ (GOT C+) and Hi narrow self-absorption (HINSA) data from international Hi 21 cm Galactic plane surveys. Methods: We identified DMG clouds with HINSA features by comparing Hi, C+, and CO spectra. We derived the Hi excitation temperature and Hi column density through spectral analysis of HINSA features. The Hi volume density was determined by utilizing the on-the-sky dimension of the cold foreground Hi cloud under the assumption of axial symmetry. The column and volume density of H2 were derived through excitation analysis of C+ emission. The derived parameters were then compared with a chemical evolutionary model. Results: We identified 36 DMG clouds with HINSA features. Based on uncertainty analysis, optical depth of HiτHi of 1 is a reasonable value for most clouds. With the assumption of τHi = 1, these clouds were characterized by excitation temperatures in a range of 20 K to 92 K with a median value of 55 K and volume densities in the range of 6.2 × 101 cm-3 to 1.2 × 103 cm-3 with a median value of 2.3 × 102 cm-3. The fraction of DMG column density in the cloud (fDMG) decreases with increasing excitation temperature following an empirical relation fDMG =-2.1 × 10-3Tex,(τHi = 1) + 1.0. The relation between fDMG and total hydrogen column density NH is given by fDMG = 1.0-3.7 × 1020/NH. We divided the clouds into a high extinction group and low extinction group with the dividing threshold being total hydrogen column density NH of 5.0 × 1021 cm-2 (AV = 2.7 mag). The values of fDMG in the low extinction group (AV ≤ 2.7 mag) are consistent with the results of the time-dependent, chemical evolutionary model at the age of ~10 Myr. Our empirical relation cannot be explained by the chemical evolutionary model for clouds in the high extinction group (AV > 2.7 mag). Compared to clouds in the low extinction group (AV ≤ 2.7 mag), clouds in the high extinction group (AV > 2.7 mag) have comparable volume densities but excitation temperatures that are 1.5 times lower. Moreover, CO abundances in clouds of the high extinction group (AV > 2.7 mag) are 6.6 × 102 times smaller than the canonical value in the Milky Way. Conclusions: The molecular gas seems to be the dominate component in these clouds. The high percentage of DMG in clouds of the high extinction group (AV > 2.7 mag) may support the idea that molecular clouds are forming from pre-existing molecular gas, I.e., a cold gas with a high H2 content but that contains a little or no CO content.

Temperature Dependence of the Rate Constant for the CH3 Recombination Reaction: A Loss Process in Outer Planet Atmospheres

NASA Technical Reports Server (NTRS)

Cody, R. J.; Payne, W. A.; Thorn, R. P., Jr.; Romani, P. N.; Stief, L. J.; Nesbitt, F. L.; Iannone, M. A.; Tardy, D. C.

2002-01-01

The methyl free radical (CH3) has been observed in the atmospheres of Saturn and Neptune by the ISO satellite. There are discrepancies between the column densities for the CH3 radical derived from the ISO observations and the column densities derived from atmospheric photochemical models. For Neptune the model column density is 1.5 times that derived from ISO. For Saturn the model is 6 times that from ISO. The recombination of methyl radicals is the major loss process for methyl in these atmospheres. The serious disagreement between observed and calculated levels of CH3 has led to suggestions that the atmospheric models greatly underestimated the loss of CH3 due to poor knowledge of the rate of the reaction (1) CH3 + CH3 + M goes to C2H6 + M at the low temperatures and pressures of these atmospheric systems. Although the reaction CH3 + CH3 + M goes to C2H6 + M has been extensively studied both theoretically and experimentally, the laboratory conditions have been, with only a few exceptions, higher temperatures (T greater than 298K), higher pressures (P greater than or equal to 10 Torr - 13.3 mbar) or M=Ar rather than H2 or He as the bath gas.

A New, Large-scale Map of Interstellar Reddening Derived from H I Emission

NASA Astrophysics Data System (ADS)

Lenz, Daniel; Hensley, Brandon S.; Doré, Olivier

2017-09-01

We present a new map of interstellar reddening, covering the 39% of the sky with low H I column densities ({N}{{H}{{I}}}< 4× {10}20 cm-2 or E(B-V)≈ 45 mmag) at 16\\buildrel{ \\prime}\\over{.} 1 resolution, based on all-sky observations of Galactic H I emission by the HI4PI Survey. In this low-column-density regime, we derive a characteristic value of {N}{{H}{{I}}}/E(B-V)=8.8 × {10}21 {{cm}}2 {{mag}}-1 for gas with | {v}{LSR}| < 90 km s-1 and find no significant reddening associated with gas at higher velocities. We compare our H I-based reddening map with the Schlegel et al. (SFD) reddening map and find them consistent to within a scatter of ≃ 5 mmag. Further, the differences between our map and the SFD map are in excellent agreement with the low-resolution (4\\buildrel{\\circ}\\over{.} 5) corrections to the SFD map derived by Peek and Graves based on observed reddening toward passive galaxies. We therefore argue that our H I-based map provides the most accurate interstellar reddening estimates in the low-column-density regime to date. Our reddening map is made publicly available at doi.org/10.7910/DVN/AFJNWJ.

Observational Tracers of Hot and Cold Gas in Isolated Galaxy Simulations

NASA Astrophysics Data System (ADS)

Brzycki, Bryan; Silvia, Devin

2018-01-01

We present results from an analysis comparing simulations of isolated spiral galaxies with recent observations of the circumgalactic medium (CGM). As the interface containing inflows and outflows between the interstellar and intergalactic media, the CGM plays an important role in the composition and evolution of galaxies. Using a set of isolated galaxy simulations over different initial conditions and star formation and feedback parameters, we investigate the evolution of CGM gas. Specifically, in light of recent observational studies, we compute the radial column density profiles and covering fractions of various observable ion species (H I, C IV, O VI, Mg II, Si III) for each simulated galaxy. Taking uniformly random sightlines through the CGM of each simulated galaxy, we find the abundance of gas absorbers and analyze their contribution to the overall column density along each sightline. By identifying the prevalence of high column density absorbers, we seek to characterize the distribution and evolution of observable ion species in the CGM. We also highlight a subset of our isolated galaxy simulations that produce and maintain a stable precipitating CGM that fuels high rates of sustained star formation. This project was supported in part by the NSF REU grant AST-1358980 and by the Nantucket Maria Mitchell Association.

Trace gas retrievals from Airborne Compact Atmospheric Mapper (ACAM) observations during the 2011 DISCOVER-AQ flight campaign

NASA Astrophysics Data System (ADS)

Liu, X.; Kowalewski, M. G.; Janz, S. J.; Bhartia, P. K.; Chance, K.; Krotkov, N. A.; Pickering, K. E.; Crawford, J. H.

2011-12-01

The DISCOVER-AQ (Deriving Information on Surface Conditions from Column and Vertically Resolved Observations Relevant to Air Quality) mission has just finished its first flight campaign in the Baltimore-Washington D.C. area in July 2011. The ACAM, flown on board the NASA UC-12 aircraft, includes two spectrographs covering the spectral region 304-900 nm and a high-definition video camera, and is expected to provide column measurements of several important air quality trace gases and aerosols for the DISCOVER-AQ mission. The quick look results for NO2 have been shown to very useful in capturing the strong spatiotemporal variability of NO2. Preliminary fitting of UV/Visible spectra has shown that ACAM measurements have adequate signal to noise ratio to measure the trace gases O2, NO2, HCHO, and maybe SO2 and CHOCHO, at individual pixel resolution, although a great deal of effort is needed to improve the instrument calibration and derive proper reference spectrum for retrieving absolute trace gas column densities. In this study, we present analysis of ACAM instrument calibration including slit function, wavelength registration, and radiometric calibration for both nadir-viewing and zenith-sky measurements. Based on this analysis, an irradiance reference spectrum at ACAM resolution will be derived from a high-resolution reference spectrum with additional correction to account for instrument calibration. Using the derived reference spectrum and/or the measured zenith sky measurements, we will perform non-linear least squares fitting to investigate the retrievals of slant column densities of these trace gases from ACAM measurements, and also use an optimal estimation based algorithm including full radiative transfer calculations to derive the vertical column densities of these trace gases. The initial results will be compared with available in-situ and ground-based measurements taken during the DISCOVER-AQ campaign.

Damped and sub-damped Lyman-α absorbers in z > 4 QSOs

NASA Astrophysics Data System (ADS)

Guimarães, R.; Petitjean, P.; de Carvalho, R. R.; Djorgovski, S. G.; Noterdaeme, P.; Castro, S.; Poppe, P. C. Da R.; Aghaee, A.

2009-12-01

We present the results of a survey of damped (DLA, log~N(H i)>20.3) and sub-damped Lyman-α systems (19.5 2.55 along the lines-of-sight to 77 quasars with emission redshifts in the range 419.5 were detected of which 40 systems are damped Lyman-α systems for an absorption length of Δ X = 378. About half of the lines of sight of this homogeneous survey have never been investigated for DLAs. We study the evolution with redshift of the cosmological density of the neutral gas and find, consistent with previous studies at similar resolution, that ΩDLA, H_I decreases at z>3.5. The overall cosmological evolution of Ω_HI shows a peak around this redshift. The H i column density distribution for log N(H i)≥20.3 is fitted, consistent with previous surveys, with a single power-law of index α ˜ -1.8 ±0.25. This power-law overpredicts data at the high-end and a second, much steeper, power-law (or a gamma function) is needed. There is a flattening of the function at lower H i column densities with an index of α ˜ -1.4 for the column density range log N(H i)=19.5-21. The fraction of H i mass in sub-DLAs is of the order of 30%. The H i column density distribution does not evolve strongly from z˜ 2.5 to z˜ 4.5. The observations reported here were obtained with the W. M. Keck Observatory, which is operated by the California Association for Research in Astronomy, a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. Tables 1, 2 and Appendices are only available in electronic form at http://www.aanda.org

THE ARIZONA RADIO OBSERVATORY CO MAPPING SURVEY OF GALACTIC MOLECULAR CLOUDS. V. THE SH2-235 CLOUD IN CO J  = 2 − 1, {sup 13}CO J  = 2 − 1, AND CO J  = 3 − 2

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bieging, John H.; Peters, William L.; Patel, Saahil

We present the results of a program to map the Sh2-235 molecular cloud complex in the CO and {sup 13}CO  J  = 2 − 1 transitions using the Heinrich Hertz Submillimeter Telescope. The map resolution is 38″ (FWHM), with an rms noise of 0.12 K brightness temperature, for a velocity resolution of 0.34 km s{sup −1}. With the same telescope, we also mapped the CO J  = 3 − 2 line at a frequency of 345 GHz, using a 64 beam focal plane array of heterodyne mixers, achieving a typical rms noise of 0.5 K brightness temperature with a velocity resolution of 0.23 km s{sup −1}.more » The three spectral line data cubes are available for download. Much of the cloud appears to be slightly sub-thermally excited in the J  = 3 level, except for in the vicinity of the warmest and highest column density areas, which are currently forming stars. Using the CO and {sup 13}CO  J  = 2 − 1 lines, we employ an LTE model to derive the gas column density over the entire mapped region. Examining a 125 pc{sup 2} region centered on the most active star formation in the vicinity of Sh2-235, we find that the young stellar object surface density scales as approximately the 1.6-power of the gas column density. The area distribution function of the gas is a steeply declining exponential function of gas column density. Comparison of the morphology of ionized and molecular gas suggests that the cloud is being substantially disrupted by expansion of the H ii regions, which may be triggering current star formation.« less

CO-dark molecular gas at high redshift: very large H2 content and high pressure in a low-metallicity damped Lyman alpha system

NASA Astrophysics Data System (ADS)

Balashev, S. A.; Noterdaeme, P.; Rahmani, H.; Klimenko, V. V.; Ledoux, C.; Petitjean, P.; Srianand, R.; Ivanchik, A. V.; Varshalovich, D. A.

2017-09-01

We present a detailed analysis of an H2-rich, extremely strong intervening damped Ly α absorption system (DLA) at zabs = 2.786 towards the quasar J 0843+0221, observed with the Ultraviolet and Visual Echelle Spectrograph on the Very Large Telescope. The total column density of molecular (resp. atomic) hydrogen is log N(H2) = 21.21 ± 0.02 (resp. log N(H I) = 21.82 ± 0.11), making it to be the first case in quasar absorption line studies with H2 column density as high as what is seen in 13CO-selected clouds in the Milky Way. We find that this system has one of the lowest metallicity detected among H2-bearing DLAs, with [Zn/H] = -1.52^{+0.08}_{-0.10}. This can be the reason for the marked differences compared to systems with similar H2 column densities in the local Universe: (I) the kinetic temperature, T ˜ 120 K, derived from the J = 0, 1 H2 rotational levels is at least twice higher than expected; (II) there is little dust extinction with AV < 0.1; (III) no CO molecules are detected, putting a constraint on the XCO factor XCO > 2 × 1023 cm-2/(km s-1 K), in the very low metallicity gas. Low CO and high H2 contents indicate that this system represents 'CO-dark/faint' gas. We investigate the physical conditions in the H2-bearing gas using the fine-structure levels of C I, C II, Si II and the rotational levels of HD and H2. We find the number density to be about n ˜ 260-380 cm-3, implying a high thermal pressure of 3-5 × 104 cm-3 K. We further identify a trend of increasing pressure with increasing total hydrogen column density. This independently supports the suggestion that extremely strong DLAs (with log N(H) ˜22) probe high-z galaxies at low impact parameters.

Numerical modeling of elution peak profiles in supercritical fluid chromatography. Part I--elution of an unretained tracer.

PubMed

Kaczmarski, Krzysztof; Poe, Donald P; Guiochon, Georges

2010-10-15

When chromatography is carried out with high-density carbon dioxide as the main component of the mobile phase (a method generally known as "supercritical fluid chromatography" or SFC), the required pressure gradient along the column is moderate. However, this mobile phase is highly compressible and, under certain experimental conditions, its density may decrease significantly along the column. Such an expansion absorbs heat, cooling the column, which absorbs heat from the outside. The resulting heat transfer causes the formation of axial and radial gradients of temperature that may become large under certain conditions. Due to these gradients, the mobile phase velocity and most physico-chemical parameters of the system (viscosity, diffusion coefficients, etc.) are no longer constant throughout the column, resulting in a loss of column efficiency, even at low flow rates. At high flow rates and in serious cases, systematic variations of the retention factors and the separation factors with increasing flow rates and important deformations of the elution profiles of all sample components may occur. The model previously used to account satisfactorily for the effects of the viscous friction heating of the mobile phase in HPLC is adapted here to account for the expansion cooling of the mobile phase in SFC and is applied to the modeling of the elution peak profiles of an unretained compound in SFC. The numerical solution of the combined heat and mass balance equations provides temperature and pressure profiles inside the column, and values of the retention time and efficiency for elution of this unretained compound that are in excellent agreement with independent experimental data. Copyright © 2010 Elsevier B.V. All rights reserved.

Impact of spatial proxies on the representation of bottom-up emission inventories: A satellite-based analysis

NASA Astrophysics Data System (ADS)

Geng, Guannan; Zhang, Qiang; Martin, Randall V.; Lin, Jintai; Huo, Hong; Zheng, Bo; Wang, Siwen; He, Kebin

2017-03-01

Spatial proxies used in bottom-up emission inventories to derive the spatial distributions of emissions are usually empirical and involve additional levels of uncertainty. Although uncertainties in current emission inventories have been discussed extensively, uncertainties resulting from improper spatial proxies have rarely been evaluated. In this work, we investigate the impact of spatial proxies on the representation of gridded emissions by comparing six gridded NOx emission datasets over China developed from the same magnitude of emissions and different spatial proxies. GEOS-Chem-modeled tropospheric NO2 vertical columns simulated from different gridded emission inventories are compared with satellite-based columns. The results show that differences between modeled and satellite-based NO2 vertical columns are sensitive to the spatial proxies used in the gridded emission inventories. The total population density is less suitable for allocating NOx emissions than nighttime light data because population density tends to allocate more emissions to rural areas. Determining the exact locations of large emission sources could significantly strengthen the correlation between modeled and observed NO2 vertical columns. Using vehicle population and an updated road network for the on-road transport sector could substantially enhance urban emissions and improve the model performance. When further applying industrial gross domestic product (IGDP) values for the industrial sector, modeled NO2 vertical columns could better capture pollution hotspots in urban areas and exhibit the best performance of the six cases compared to satellite-based NO2 vertical columns (slope = 1.01 and R2 = 0. 85). This analysis provides a framework for information from satellite observations to inform bottom-up inventory development. In the future, more effort should be devoted to the representation of spatial proxies to improve spatial patterns in bottom-up emission inventories.

Simultaneous UV and X-ray Spectroscopy of the Seyfert 1 Galaxy NGC 5548. I: Physical Conditions in the UV Absorbers

NASA Technical Reports Server (NTRS)

Crenshaw, D. M.; Kraemer, S. B.; Gabel, J. R.; Kaastra, J. S.; Steenbrugge, K. C.; Brinkman, A. C.; Dunn, J. P.; George, I. M.; Liedahl, D. A.; Paerels, F. B. S.

2003-01-01

We present new UV spectra of the nucleus of the Seyfert 1 galaxy NGC 5548, which we obtained with the Space Telescope Imaging Spectrograph at high spectral resolution, in conjunction with simultaneous Chandra X-ray Observatory spectra. Taking advantage of the low UV continuum and broad emission-line fluxes, we have determined that the deepest UV absorption component covers at least a portion of the inner, high-ionization narrow-line region (NLR). We find nonunity covering factors in the cores of several kinematic components, which increase the column density measurements of N V and C IV by factors of 1.2 to 1.9 over the full-covering case; however, the revised columns have only a minor effect on the parameters derived from our photoionization models. For the first time, we have simultaneous N V and C IV columns for component 1 (at -1040 km/s), and find that this component cannot be an X-ray warm absorber, contrary to our previous claim based on nonsimultaneous observations. We find that models of the absorbers based on solar abundances severely overpredict the O VI columns previously obtained with the Far Ultraviolet Spectrograph, and present arguments that this is not likely due to variability. However, models that include either enhanced nitrogen (twice solar) or dust, with strong depletion of carbon in either case, are successful in matching all of the observed ionic columns. These models result in substantially lower ionization parameters and total column densities compared to dust-free solar-abundance models, and produce little O VII or O VIII, indicating that none of the UV absorbers are X-ray warm absorbers.

Advanced intermediate temperature sodium copper chloride battery

NASA Astrophysics Data System (ADS)

Yang, Li-Ping; Liu, Xiao-Min; Zhang, Yi-Wei; Yang, Hui; Shen, Xiao-Dong

2014-12-01

Sodium metal chloride batteries, also called as ZEBRA batteries, possess many merits such as low cost, high energy density and high safety, but their high operation temperature (270-350 °C) may cause several issues and limit their applications. Therefore, decreasing the operation temperature is of great importance in order to broaden their usage. Using a room temperature ionic liquid (RTIL) catholyte composed of sodium chloride buffered 1-ethyl-3-methylimidazolium chloride-aluminum chloride and a dense β″-aluminates solid electrolyte film with 500 micron thickness, we report an intermediate temperature sodium copper chloride battery which can be operated at only 150 °C, therefore alleviating the corrosion issues, improving the material compatibilities and reducing the operating complexities associated with the conventional ZEBRA batteries. The RTIL presents a high ionic conductivity (0.247 S cm-1) at 150 °C and a wide electrochemical window (-2.6 to 2.18 vs. Al3+/Al). With the discharge plateau at 2.64 V toward sodium and the specific capacity of 285 mAh g-1, this intermediate temperature battery exhibits an energy density (750 mWh g-1) comparable to the conventional ZEBRA batteries (728-785 mWh g-1) and superior to commercialized Li-ion batteries (550-680 mWh g-1), making it very attractive for renewable energy integration and other grid related applications.

Influence of temperature on the myocardial cells death by an extracellular talaporfin sodium-induced photosensitization reaction

NASA Astrophysics Data System (ADS)

Ogawa, Emiyu; Takenoya, Hiromi; Arai, Tsunenori

2016-03-01

We have proposed to apply the photosensitization reaction in myocardium interstitial fluid using talaporfin sodium to realize less-heated electrical conduction block for a tachyarrhythmia treatment: PD Ablation®. The cytotoxicity of the extracellular photosensitization reaction efficiency may change by the talaporfin sodium binding with serum proteins. These binding would change with solution temperature. We investigated the binding behavior of talaporfin sodium with human serum albumin (HSA), high-density lipoprotein (HDL), and low-density lipoprotein (LDL) changing solution temperature from 17 to 37°C. We also studied the photocytotoxicity change by solution temperature of 17 and 37°C measuring cell lethality by WST assay using fetal bovine serum. The binding ratio of talaporfin sodium with HDL and LDL decreased 6.3% and 12.8% with temperature increasing from 17 to 37°C. There was no significant difference in the case of HSA. The cell lethality was increased about 30% with temperature increasing from 17 to 37°C. The myocardium tissue temperature increase was reported that less than 5°C in the case of our PD Ablation®. We think that the photocytotoxicity change by these temperature increasing would be negligible in our PD Ablation®. We suggest that the temperature maintaining would be necessary to keep the photocytotoxicity efficiency in the case of the open surgery that would cause the tissue surface temperature decreasing.

Lipoprotein Agarose Gel Electrophoresis. Application in HDL-Cholesterol Methodology.

DTIC Science & Technology

1985-06-01

on determination of high-density lipo- protein cholesterol by precipitation with sodium phosphotungstate- magnesium. Clin Chem 25(4):560 (1979). 6...determinations of cholesterol levels in supernates obtained after addition of various amounts of precipitants , lipo- protein electrophoresis can help to...plotted against the corresponding volumes of sodium phosphotungstate-MgCl2 (NAPT) precipitant added. 10 ’ ’’ ’i - n