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Sample records for chemical concentration

  1. Experimental study of chemical concentration variation of ASP flooding

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    A physical modeling system of long slim tube was established. Several pressure measuring and sampling points were laid out at different positions along the tube. Through real-time measurements of pressures and chemical concentrations at different points, the mass transfer and chemical concentration of ASP flooding in porous media are studied. The concentration of chemicals declines gradually during the fluid flow from the inlet to the outlet of the model. The concentration increases in the front edge of the slug faster than the concentration decreases in the rear edge of the slug. The concentration variation of the chemicals is an asymmetrical and offset process. The order of motion velocities of the chemicals from fast to slow is polymer, alkali and surfactant. The motion lag and comprehensive diffusion are strong in the vicinity of the inlet, the motion velocities of the chemicals are high, the difference of flow velocities among the three chemicals is significant and the chromatographic separation of the chemicals is obvious. In the area near the outlet, the comprehensive diffusion and motion lag become weak, the concentrations of the chemicals decrease, the motion velocities of the chemicals are slow, the difference among the motion velocities of the chemicals becomes small, the chromatographic separation is not obvious, the adsorption and retention of chemicals gradually increase as the chemical slug moves further along the tube, the adsorption and retention of polymer is the most serious.

  2. [Stressful effects of chemical toxins at low concentrations].

    Science.gov (United States)

    Parfeniuk, S B; Khrenov, M O; Novoselova, T V; Glushkova, O V; Lunin, S M; Fesenko, E E; Novoselova, E G

    2010-01-01

    Effects of three chemical compounds: ammonia, diethyl ether, and acetic acid, known as common environmental contaminants in technogenic accidents, were investigated in vivo and in vitro in low concentrations. When added in cultivation media, each of the chemicals has affected peritoneal macrophages and spleen lymphocytes isolated from male NMRI mice and led to a rise in the production of several cytokines, particularly the tumor necrosis factor-alpha and interferon-gamma, as well as the expression of the inducible form of heat shock proteins (HSP72 and HSP90-alpha) and in the activation of signal cascades NF-kappaB and SAPK/JNK. The increase of the nitric oxide (NO) production in macrophages has been observed only when ammonia was added in cultivation media. Also, low concentrations of all compounds investigated led to the activation of the expression of receptor protein TLR4. When mice were exposed to airborne toxic contaminants in a hermetically sealed experimental chamber, an increase in the concentrations of cytokines, heat shock proteins, and signal proteins in immune cells was also observed in response to low concentrations of all chemicals investigated. Similarly to in vitro experiments, the NO production was augmented only in the presence of the airborne ammonia. The results indicate the environmental hazard of chemical contaminants even in rather low concentrations, which nevertheless lead to the stress response.

  3. Communicating serum chemical concentrations to study participants: follow up survey

    Directory of Open Access Journals (Sweden)

    Louis Germaine M

    2010-05-01

    Full Text Available Abstract Background A considerable literature now supports the importance of effective communication with study participants, including how best to develop communication plans focusing on the uncertainty of health risks associated with particular environmental exposures. Strategies for communicating individual concentrations of environmental chemicals in human biological samples in the absence of clearly established safe or hazardous levels have been discussed from a conceptual basis and to a lesser extent from an empirical basis. We designed and evaluated an empirically based communication strategy for women of reproductive age who previously participated in a prospective study focusing on persistent environmental chemicals and reproductive outcomes. Methods A cohort of women followed from preconception through pregnancy or up to 12 menstrual cycles without pregnancy was given their individual serum concentrations for lead, dichloro-2,2-bisp-chlorophenyl ethylene, and select polychlorinated biphenyl congeners. Two versions of standardized letters were prepared depending upon women's exposure status, which was characterized as low or high. Letters included an introduction, individual concentrations, population reference values and guidance for minimizing future exposures. Participants were actively monitored for any questions or concerns following receipt of letters. Results Ninety-eight women were sent letters informing them of their individual concentrations to select study chemicals. None of the 89 (91% participating women irrespective of exposure status contacted the research team with questions or concerns about communicated exposures despite an invitation to do so. Conclusions Our findings suggest that study participants can be informed about their individual serum concentrations without generating unnecessary concern.

  4. Natural radioactivity and chemical concentrations in Egyptian groundwater.

    Science.gov (United States)

    Amin, Rafat M; Khalil, F A; El Fayoumi, M A K

    2011-02-01

    Measurements of natural radioactivity in drinking water have been performed in many parts of the world, mostly for assessment of the doses and risk resulting from consuming water. A study of the radionuclide and chemical components in groundwater from Beni Suef Governate, Egypt has been carried out. Fifty water samples were analyzed by gamma ray spectroscopy to determine the 226Ra, 232Th, and 40K concentrations; major elements, pH, alkalinity, and conductivity were also measured. The specific activity values ranged from 0.008 to 0.040 Bq/l for 226Ra, from 0.003 to 0.019 Bq/l for 232Th, and from 0.025 to 0.344 Bq/l for 40K. The annual ingestions of these radionuclides, using local consumption rates (average over the whole population) of 1.5 l day(-1), were estimated to be 8.59, 4.86, and 83.47 Bq year(-1) for 226Ra, 232Th, and 40K, respectively. The estimated values and weighted means of these radionuclides compare well with the world average. The estimated effective doses from drinking water were found to be 2.4 μSv year(-1) (226Ra), 1.1 μSv year(-1) (232Th), and 0.51 μSv year(-1) (40K). Contribution of these radionuclides to the committed effective dose from 1 year consumption of drinking water is estimated to be only 4%.

  5. Fluxes of chemically reactive species inferred from mean concentration measurements

    NARCIS (Netherlands)

    Galmarini, S.; Vilà-Guerau De Arellano, J.; Duyzer, J.H.

    1997-01-01

    A method is presented for the calculation of the fluxes of chemically reactive species on the basis of routine measurements of meteorological variables and chemical species. The method takes explicity into account the influence of chemical reactions on the fluxes of the species. As a demonstration o

  6. GEOSTATISTICAL INTERPOLATION OF CHEMICAL CONCENTRATION. (R825689C037)

    Science.gov (United States)

    AbstractMeasurements of contaminant concentration at a hazardous waste site typically vary over many orders of magnitude and have highly skewed distributions. This work presents a practical methodology for the estimation of solute concentration contour maps and volume...

  7. Aquatic concentrations of chemical analytes compared to ecotoxicity estimates

    Data.gov (United States)

    U.S. Environmental Protection Agency — We describe screening level estimates of potential aquatic toxicity posed by 227 chemical analytes that were measured in 25 ambient water samples collected as part...

  8. Conversion of the chemical concentration of odorous mixtures into odour concentration and odour intensity: a comparison of methods

    CERN Document Server

    Wu, C; Zhao, P; Piringer, M; Schauberger, G

    2015-01-01

    Continuous odour measurements both of emissions as well as ambient concentrations are seldom realised, mainly because of their high costs. They are therefore often substituted by concentration measurements of odorous substances. Then a conversion of the chemical concentrations C (mg m-3) into odour concentrations COD (ouE m-3) and odour intensities OI is necessary. Four methods to convert the concentrations of single substances to the odour concentrations and odour intensities of an odorous mixture are investigated: (1) direct use of measured concentrations, (2) the sum of the odour activity value SOAV, (3) the sum of the odour intensities SOI, and (4) the equivalent odour concentration EOC, as a new method. The methods are evaluated with olfactometric measurements of seven substances as well as their mixtures. The results indicate that the SOI and EOC conversion methods deliver reliable values. These methods use not only the odour threshold concentration but also the slope of the Weber-Fechner law to include...

  9. Concentration of 'forgotten' substances using the XAD concentration method. Suitability of the method for hydrophilic chemicals

    NARCIS (Netherlands)

    Collombon MT; LER

    2007-01-01

    Concentration of forgotten substances using the XAD concentration method In the nineties, RIVM developed a method to concentrate toxic substances on XAD (a synthetic resin). Using bioassays, the toxicity can be determined in the concentrate. 'Modern' toxic substances tend to be more polar then 'clas

  10. Dependence of maximum concentration from chemical accidents on release duration

    Science.gov (United States)

    Hanna, Steven; Chang, Joseph

    2017-01-01

    Chemical accidents often involve releases of a total mass, Q, of stored material in a tank over a time duration, td, of less than a few minutes. The value of td is usually uncertain because of lack of knowledge of key information, such as the size and location of the hole and the pressure and temperature of the chemical. In addition, it is rare that eyewitnesses or video cameras are present at the time of the accident. For inhalation hazards, serious health effects (such as damage to the respiratory system) are determined by short term averages (pressurized liquefied chlorine releases from tanks are given, focusing on scenarios from the Jack Rabbit I (JR I) field experiment. The analytical calculations and the predictions of the SLAB dense gas dispersion model agree that the ratio of maximum C for two different td's is greatest (as much as a factor of ten) near the source. At large distances (beyond a few km for the JR I scenarios), where tt exceeds both td's, the ratio of maximum C approaches unity.

  11. Physico-Chemical changes in valencia orange concentrate during commercial scale vacuum concentration

    Directory of Open Access Journals (Sweden)

    J. S. Pruthi

    1959-01-01

    Full Text Available "Changes in the refractometric solids (Brix, viscosity, spectral reflectance (color, pH, acidity, Brix/acid ratio, color, true ascorbic acid and carotene during commercial scale vacuum concentration of Valencia orange juice in a forced circulation, single-pass, falling-film Evaporator have been reported. With the advancing concentration, there was a gradual increase in Brix, acidity, viscosity, color, ascorbic acid and carotene, no change in Brix/acid ratio but a slight fall in pH. Upto 4-fold concentration of the Juice, the increase in viscosity was comparatively slight, but after 5-fold concentration, there was a steep rise in viscosity. There were negligible losses in carotene while the losses in true ascorbic acid were well within 5% during concentration up to 63Degree Brix. Use of mid-season, healthy ripe oranges for juice extraction and concentration of the flash-heated juice (195Degree-200DegreeF for 10-12 seconds upto 5-fold concentration are suggested."

  12. Determination of solute organic concentration in contaminated soils using a chemical-equilibrium soil column system

    DEFF Research Database (Denmark)

    Gamst, Jesper; Kjeldsen, Peter; Christensen, Thomas Højlund

    2007-01-01

    Groundwater risk assessment of contaminated soils implies determination of the solute concentration leaching out of the soil. Determination based on estimation techniques or simple experimental batch approach has proven inadequate. Two chemical equilibrium soil column leaching tests...... for determination of solute concentration in a contaminated soil were developed; (1) a chemical Equilibrium and Recirculation column test for Volatile organic chemicals (ER-V) and (2) a chemical Equilibrium and Recirculation column test for Hydrophobic organic chemicals (ER-H). The two test systems were evaluated...... to measure solute phase concentration of PAHs in contaminated soils. Overall a reliable and reproducable system for determining solute concentration of a wide range of organic compounds in contaminated soils has been developed....

  13. Radiocarbon from Pile Graphite; Chemical Methods for Its Concentrations

    Science.gov (United States)

    Arnold, J. R.; Libby, W. F.

    1946-10-10

    Samples of pile graphite, irradiated in a test-hole at Hanford for 15 months, have been assayed for radioactive C{sup 14} yielding 0.38 ± 0.04 microcuries per gram. At this level of activity, the pile graphite contains very valuable amounts of C{sup14}. The relation between the above assay and the probable average assay of pile graphite is discussed, and it is concluded that the latter is almost certainly above 0.3 microcuries/gram. Controlled oxidation of this graphite, either with oxygen at ~750ºC, or with chromic acid "cleaning solution" at room temperature, yields early fractions which are highly enriched in C{sup 14}. Concentrations of 5-fold with oxygen, and 50-fold with CrO{sub 3}, have been observed. The relation between the observed enrichment and the Wigner effect is discussed, and a mechanism accounting for the observations put forward. According to this, about 25% of the stable carbon atoms in the lattice have been displaced by Wigner effect, a large fraction of which have healed by migrating to crystal edges. All the C{sup 14} atoms have been displaced, and the same fraction of these migrate to the edges. The enrichment then results from surface oxidation, in the oxygen case. Predictions are made on the basis of this hypothesis. A technique of counting radioactive CO{sub 2} in the gas phase is described.

  14. Effect of etchant concentration on microwave induced chemical etching (MICE) of CR-39 detector

    Energy Technology Data Exchange (ETDEWEB)

    Sahoo, G.S. [Health Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Tripathy, S.P., E-mail: sam.tripathy@gmail.com [Health Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Sharma, S.D. [Radiological Physics and Advisor Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Homi Bhabha National Institute, Mumbai 400094 (India); Bandyopadhyay, T. [Health Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Homi Bhabha National Institute, Mumbai 400094 (India)

    2015-11-11

    The recently introduced microwave induced chemical etching (MICE) has been found to be a fast and effective etching technique for CR-39 detector. In the present work, the MICE technique was used to develop the neutron induced recoil tracks in CR-39 detectors. Special attention was paid in carrying out a systematic investigation to study the effect of etchant concentration and microwave power on the development of tracks and various track parameters. NaOH solution of different concentrations, viz. 3–8 N was tested at 300, 450, 600 and 900 W of microwave power. Temperature profiles for 200 ml solution of each concentration were generated to maintain a fixed operating condition for all concentrations at each microwave power. The bulk etch rate was found to increase with the microwave power as well as with the etchant concentration. Empirical relations were established to relate the variation of bulk etch rate with microwave power and etchant concentration.

  15. Arsenic concentrations in Baltic Sea sediments close to chemical munitions dumpsites

    Science.gov (United States)

    Bełdowski, Jacek; Szubska, Marta; Emelyanov, Emelyan; Garnaga, Galina; Drzewińska, Anna; Bełdowska, Magdalena; Vanninen, Paula; Östin, Anders; Fabisiak, Jacek

    2016-06-01

    In addition to natural sources and land-originated pollution, the Baltic Sea has another anthropogenic source of arsenic in bottom sediments-arsenic-based Chemical Warfare Agents (CWA). To examine the potential usage of arsenic contents results for monitoring the leakage from chemical weapons, sediment samples were collected from officially reported and potential chemical weapon dumpsites located in the Baltic Sea, and total and inorganic arsenic concentrations were analyzed. Results showed an elevated arsenic content in dumpsite areas compared to reference areas. Correlations of arsenic with other metals and organic matter were studied to elucidate any unusual behavior of arsenic in the dumpsites. In the area of the Bornholm Deep, such behavior was observed for inorganic arsenic. It appears that in close vicinity of dumped munitions, the inorganic arsenic concentration of sediments is not correlated with either organic matter content or authigenic minerals formation, as is commonly observed elsewhere. Investigations on CWA concentrations, performed within the CHEMSEA (Chemical Munition Search and Assesment) project, allowed us to compare the results of arsenic concentrations with the occurrence of arsenic-containing CWA.

  16. Chemical composition, functional and pasting properties of cassava starch and soy protein concentrate blends

    OpenAIRE

    2011-01-01

    The chemical, functional and pasting properties of cassava starch and soy protein concentrate blends intended for biofilm processing were studied. Cassava starch and soy protein concentrates were prepared and mixed at different proportions (100: 0%; 90 : 10%; 80 : 20%; 70 : 30%; 60;40% and 50: 50%). Addition of varying levels of soy protein concentrates to cassava starch led to increases in moisture (from 7.10 to 9.17%), protein ( from 0.32 to 79.03%), ash (from 0.45 to 2.67%) and fat (from 0...

  17. Ambient Concentrations of Metabolic Disrupting Chemicals and Children’s Academic Achievement in El Paso, Texas

    Science.gov (United States)

    Clark-Reyna, Stephanie E.; Grineski, Sara E.; Collins, Timothy W.

    2016-01-01

    Concerns about children’s weight have steadily risen alongside the manufacture and use of myriad chemicals in the US. One class of chemicals, known as metabolic disruptors, interfere with human endocrine and metabolic functioning and are of specific concern to children’s health and development. This article examines the effect of residential concentrations of metabolic disrupting chemicals on children’s school performance for the first time. Census tract-level ambient concentrations for known metabolic disruptors come from the US Environmental Protection Agency’s National Air Toxics Assessment. Other measures were drawn from a survey of primary caretakers of 4th and 5th grade children in El Paso Independent School District (El Paso, TX, USA). A mediation model is employed to examine two hypothetical pathways through which the ambient level of metabolic disruptors at a child’s home might affect grade point average. Results indicate that concentrations of metabolic disruptors are statistically significantly associated with lower grade point averages directly and indirectly through body mass index. Findings from this study have practical implications for environmental justice research and chemical policy reform in the US. PMID:27598179

  18. Influence of chemical disorder on energy dissipation and defect evolution in concentrated solid solution alloys.

    Science.gov (United States)

    Zhang, Yanwen; Stocks, G Malcolm; Jin, Ke; Lu, Chenyang; Bei, Hongbin; Sales, Brian C; Wang, Lumin; Béland, Laurent K; Stoller, Roger E; Samolyuk, German D; Caro, Magdalena; Caro, Alfredo; Weber, William J

    2015-10-28

    A grand challenge in materials research is to understand complex electronic correlation and non-equilibrium atomic interactions, and how such intrinsic properties and dynamic processes affect energy transfer and defect evolution in irradiated materials. Here we report that chemical disorder, with an increasing number of principal elements and/or altered concentrations of specific elements, in single-phase concentrated solid solution alloys can lead to substantial reduction in electron mean free path and orders of magnitude decrease in electrical and thermal conductivity. The subsequently slow energy dissipation affects defect dynamics at the early stages, and consequentially may result in less deleterious defects. Suppressed damage accumulation with increasing chemical disorder from pure nickel to binary and to more complex quaternary solid solutions is observed. Understanding and controlling energy dissipation and defect dynamics by altering alloy complexity may pave the way for new design principles of radiation-tolerant structural alloys for energy applications.

  19. Effects of catalyst concentration and ultraviolet intensity on chemical mechanical polishing of GaN

    Science.gov (United States)

    Wang, Jie; Wang, Tongqing; Pan, Guoshun; Lu, Xinchun

    2016-08-01

    Effects of catalyst concentration and ultraviolet intensity on chemical mechanical polishing (CMP) of GaN were deeply investigated in this paper. Working as an ideal homogeneous substrate material in LED industry, GaN ought to be equipped with a smooth and flat surface. Taking the strong chemical stability of GaN into account, photocatalytic oxidation technology was adopted in GaN CMP process to realize efficient removal. It was found that, because of the improved reaction rate of photocatalytic oxidation, GaN material removal rate (MRR) increases by a certain extent with catalyst concentration increasing. Cross single line analysis on the surface after polishing by Phase Shift MicroXAM-3D was carried out to prove the better removal effect with higher catalyst concentration. Ultraviolet intensity field in H2O2-SiO2-based polishing system was established and simulated, revealing the variation trend of ultraviolet intensity around the outlet of the slurry. It could be concluded that, owing to the higher planarization efficiency and lower energy damage, the UV lamp of 125 W is the most appropriate lamp in this system. Based on the analysis, defects removal model of this work was proposed to describe the effects of higher catalyst concentration and higher power of UV lamp.

  20. Concentration of mycotoxins and chemical composition of corn silage: a farm survey using infrared thermography.

    Science.gov (United States)

    Schmidt, P; Novinski, C O; Junges, D; Almeida, R; de Souza, C M

    2015-09-01

    This work evaluated the chemical composition and mycotoxin incidence in corn silage from 5 Brazilian dairy-producing regions: Castro, in central-eastern Paraná State (n=32); Toledo, in southwestern Paraná (n=20); southeastern Goiás (n=14); southern Minas Gerais (n=23); and western Santa Catarina (n=20). On each dairy farm, an infrared thermography camera was used to identify 3 sampling sites that exhibited the highest temperature, a moderate temperature, and the lowest temperature on the silo face, and 1 sample was collected from each site. The chemical composition and concentrations of mycotoxins were evaluated, including the levels of aflatoxins B1, B2, G1, and G2; zearalenone; ochratoxin A; deoxynivalenol; and fumonisins B1 and B2. The corn silage showed a highly variable chemical composition, containing, on average, 7.1±1.1%, 52.5±5.4%, and 65.2±3.6% crude protein, neutral detergent fiber, and total digestible nutrients, respectively. Mycotoxins were found in more than 91% of the samples, with zearalenone being the most prevalent (72.8%). All samples from the Castro region contained zearalenone at a high average concentration (334±374µg/kg), even in well-preserved silage. The incidence of aflatoxin B1 was low (0.92%). Silage temperature and the presence of mycotoxins were not correlated; similarly, differences were not observed in the concentration or incidence of mycotoxins across silage locations with different temperatures. Infrared thermography is an accurate tool for identifying heat sites, but temperature cannot be used to predict the chemical composition or the incidence of mycotoxins that have been analyzed, within the silage. The pre-harvest phase of the ensiling process is most likely the main source of mycotoxins in silage.

  1. Contact irritant responses of Aedes aegypti Using sublethal concentration and focal application of pyrethroid chemicals.

    Directory of Open Access Journals (Sweden)

    Hortance Manda

    Full Text Available BACKGROUND: Previous studies have demonstrated contact irritant and spatial repellent behaviors in Aedes aegypti following exposure to sublethal concentrations of chemicals. These sublethal actions are currently being evaluated in the development of a push-pull strategy for Ae. aegypti control. This study reports on mosquito escape responses after exposure to candidate chemicals for a contact irritant focused push-pull strategy using varying concentrations and focal application. METHODS: Contact irritancy (escape behavior, knockdown and 24 hour mortality rates were quantified in populations of female Ae. aegypti under laboratory conditions and validated in the field (Thailand and Peru using experimental huts. Evaluations were conducted using varying concentrations and treatment surface area coverage (SAC of three pyrethroid insecticides: alphacypermethrin, lambacyhalothrin and deltamethrin. RESULTS: Under laboratory conditions, exposure of Ae. aegypti to alphacypermethrin using the standard field application rate (FAR resulted in escape responses at 25% and 50% SAC that were comparable with escape responses at 100% SAC. Significant escape responses were also observed at <100% SAC using ½FAR of all test compounds. In most trials, KD and 24 hour mortality rates were higher in mosquitoes that did not escape than in those that escaped. In Thailand, field validation studies indicated an early time of exit (by four hours and 40% increase in escape using ½FAR of alphacypermethrin at 75% SAC compared to a matched chemical-free control. In Peru, however, the maximum increase in Ae. aegypti escape from alphacypermethrin-treated huts was 11%. CONCLUSIONS/SIGNIFICANCE: Results presented here suggest a potential role for sublethal and focal application of contact irritant chemicals in an Ae. aegypti push-pull strategy to reduce human-vector contact inside treated homes. However, the impact of an increase in escape response on dengue virus transmission is

  2. The Polyphenols Stability, Enzyme Activity and Physico-Chemical Parameters During Producing Wild Elderberry Concentrated Juice

    Directory of Open Access Journals (Sweden)

    Ante Galić

    2009-12-01

    Full Text Available The influence of processing wild elderberry into concentrated juice on polyphenols (total phenols, flavonoids, non-flavonoids, anthocyanins, flavan-3-ols, hydrolysed tannins stability, activity of polyphenol oxidase (PPO and peroxidase (POD, and changes of physico-chemical parameters (total and soluble dry matter, total acidity, pH, sugars were investigated. The amounts of total phenols, flavonoids, non-flavonoids, falvan-3-ols and hydrolysed tannins were analyzed using Folin-Ciocalteu colorimetric method, while the total anthocyanins were determined by bisulphite bleaching method. Total phenols ranged from 25.87 mg/g DM to 38.87 mg/g DM. Total anthocyanins were the most abundant polyphenols in all investigated samples (raw elderberries, elderberries after blanching, elderberry juice after disintegration and pressing, concentrated elderberry juice and their concentration ranged from 13.12 mg/g DM to 25.67 mg/g DM. Other polyphenols determined in high concentration were hydrolysed tannins, followed by fl avan-3-ols, flavonoids and nonfavonoids. After blanching, the concentration of all polyphenols did not decrease significantly. After disintegration of elderberries the concentration of all polyphenols increased, probably due to inactivation of PPO and POD and better isolation of polyphenols from homogenized puree. During processing of elderberry juice into concentrated juice most polyphenols were stable. Total acidity and pH value were not changed during processing, whereas the amounts of total and reducing sugar increased after pressing and additionally after concentration. The obtained results suggest that raw elderberries as well as elderberry concentrated juice are high potential source of polyphenols especially anthocyanins.

  3. Modeling precipitation from concentrated solutions with the EQ3/6 chemical speciation codes

    Energy Technology Data Exchange (ETDEWEB)

    Brown, L.F.; Ebinger, M.H.

    1995-01-13

    One of the more important uncertainties of using chemical speciation codes to study dissolution and precipitation of compounds is the results of modeling which depends on the particular thermodynamic database being used. The authors goal is to investigate the effects of different thermodynamic databases on modeling precipitation from concentrated solutions. They used the EQ3/6 codes and the supplied databases to model precipitation in this paper. One aspect of this goal is to compare predictions of precipitation from ideal solutions to similar predictions from nonideal solutions. The largest thermodynamic databases available for use by EQ3/6 assume that solutions behave ideally. However, two databases exist that allow modeling nonideal solutions. The two databases are much less extensive than the ideal solution data, and they investigated the comparability of modeling ideal solutions and nonideal solutions. They defined four fundamental problems to test the EQ3/6 codes in concentrated solutions. Two problems precipitate Ca(OH){sub 2} from solutions concentrated in Ca{sup ++}. One problem tests the precipitation of Ca(OH){sub 2} from high ionic strength (high concentration) solutions that are low in the concentrations of precipitating species (Ca{sup ++} in this case). The fourth problem evaporates the supernatant of the problem with low concentrations of precipitating species. The specific problems are discussed.

  4. Reverse osmosis concentrate treatment by chemical oxidation and moving bed biofilm processes.

    Science.gov (United States)

    Vendramel, S M R; Justo, A; González, O; Sans, C; Esplugas, S

    2013-01-01

    In the present work, four oxidation techniques were investigated (O3, O3/UV, H2O2/O3, O3/H2O2/UV) to pre-treat reverse osmosis (RO) concentrate before treatment in a moving-bed biofilm reactor (MBBR) system. Without previous oxidation, the MBBR was able to remove a small fraction of the chemical oxygen demand (COD) (5-20%) and dissolved organic carbon (DOC) (2-15%). When the concentrate was previously submitted to oxidation, DOC removal efficiencies in the MBBR increased to 40-55%. All the tested oxidation techniques improved concentrate biodegradability. The concentrate treated by the combined process (oxidation and MBBR) presented residual DOC and COD in the ranges of 6-12 and 25-41 mg L(-1), respectively. Nitrification of the RO concentrate, pre-treated by oxidation, was observed in the MBBR. Ammonium removal was comprised between 54 and 79%. The results indicate that the MBBR was effective for the treatment of the RO concentrate, previously submitted to oxidation, generating water with an improved quality.

  5. Particulate matter concentration and chemical composition in the metro system of Rome, Italy.

    Science.gov (United States)

    Perrino, C; Marcovecchio, F; Tofful, L; Canepari, S

    2015-06-01

    Air quality at the main station of the metro system of Rome (Termini hub) has been characterized by the point of view of particulate matter (PM) concentration and chemical composition. Indoor air in different environments (underground train platform and shopping center, metro carriages with and without air conditioning system) has been studied and compared with outdoor air at a nearby urban site. Air quality at the railway station, located outdoor at surface level, has been also considered for comparison. PM chemical characterization included ions, elemental carbon, organic carbon, macro-elements, and the bio-accessible and residual fractions of micro- and trace elements. Train platform and carriages without air conditioning resulted to be the most polluted environments, with indoor/outdoor ratio up to two orders of magnitude for many components. PM mass concentration was determined on filter membranes by the gravimetric procedure as well as from the optical particle counter (OPC) number concentration measurements. The OPC results, taken with the original calibration factor, were below 40 % of the value obtained by the gravimetric measurements. Only a chemical and morphological characterization of the collected dust could lead to a reconciliation of the results yielded by the two methods. Macro-components were used to estimate the strength of the main macro-sources. The most significant contribution is confirmed to derive from wheels, rails, and brakes abrasion; from soil re-suspension (over 50 % at the subway platform); and from organics (about 25 %). The increase in the concentration of elements was mostly due to the residual fraction, but also the bio-accessible fraction showed a remarkable enrichment, particularly in the case of Ba, Zn, Cd, and Ni.

  6. Adaptation of fugacity models to treat speciating chemicals with constant species concentration ratios.

    Science.gov (United States)

    Toose, Liisa K; Mackay, Donald

    2004-09-01

    A "multiplier" method is developed by which multimedia mass balance fugacity models designed to describe the fate of a single chemical species can be applied to chemicals that exist as several interconverting species. The method is applicable only when observed ratios of species concentrations in each phase are relatively constant and there is thus no need to define interspecies conversion rates. It involves the compilation of conventional transformation and intermedia transport rate expressions for a single, selected key species, and then a multiplier, Ri, is deduced for each of the other species. The total rate applicable to all species is calculated as the product of the rate for the single key species and a combined multiplier (1 + R2 + R3 + etc.). The theory is developed and illustrated by two examples. Limitations of the method are discussed, especially under conditions when conversion rates are uncertain. The advantage of this approach is that existing fugacity and concentration-based models that describe the fate of single-species chemicals can be readily adapted to estimate the fate of multispecies substances such as mercury which display relatively constant species proportions in each medium.

  7. Comparing wastewater chemicals, indicator bacteria concentrations, and bacterial pathogen genes as fecal pollution indicators

    Science.gov (United States)

    Haack, S.K.; Duris, J.W.; Fogarty, L.R.; Kolpin, D.W.; Focazio, M.J.; Furlong, E.T.; Meyer, M.T.

    2009-01-01

    The objective of this study was to compare fecal indicator bacteria (FIB) (fecal coliforms, Escherichia coli [EC], and enterococci [ENT]) concentrations with a wide array of typical organic wastewater chemicals and selected bacterial genes as indicators of fecal pollution in water samples collected at or near 18 surface water drinking water intakes. Genes tested included esp (indicating human-pathogenic ENT) and nine genes associated with various animal sources of shiga-toxin-producing EC (STEC). Fecal pollution was indicated by genes and/or chemicals for 14 of the 18 tested samples, with little relation to FIB standards. Of 13 samples with Society of Agronomy, Crop Science Society of America, and Soil Science Society of America. All rights reserved.

  8. Evaluation of Cu Ion Concentration Effects on Cu Etching Rate in Chemical-Mechanical Polishing Slurry

    Science.gov (United States)

    Nishizawa, Hideaki; Sugiura, Osamu; Matsumura, Yoshiyuki; Kinoshita, Masaharu

    2007-04-01

    The effects of Cu ion concentration of the different solutions on Cu etching rate were investigated. From the dipping experiment of Cu substrates in different solutions of malic acid, hydrogen peroxide (H2O2), benzotriazole (BTA), and Cu ions, it was revealed that Cu etching rate is increased if the concentration of Cu(II) ions added in the solution is high. This is considered to be caused by the effect of Cu(II) ions on H2O2 molecules. In the solution of pH 7, the Cu etching rate increased markedly between 1.7× 10-4 and 3.4× 10-4 M Cu(II) ion concentrations. The maximum increase in the etching rate was from 990 to 2200 nm/min at a H2O2 concentration of 2 wt %. In the solution of pH 3, a marked change in the etching rate was not observed. Our results show that the concentration of Cu ions on the polishing pad in chemical-mechanical polishing (CMP) process is very important.

  9. Chemical mutagenesis--a promising technique to increase metal concentration and extraction in sunflowers.

    Science.gov (United States)

    Nehnevajova, Erika; Herzig, Rolf; Federer, Guido; Erismann, Karl-Hans; Schwitzguébel, Jean-Paul

    2007-01-01

    Since most of the metal-hyperaccumulating wild plants only produce very low biomass and many high-yielding crops accumulate only moderate amounts of metals, the current research is mainly focused on overcoming these limitations and the optimization of metal phytoextraction. The main goal of the present study was the improvement of metal concentration and extraction properties of Helianthus annuus L by chemical mutagenesis (the non-GMO approach). Sunflowers--hybrid cultivar Salut and inbred lines-were treated with the chemical mutagen ethyl methanesulfonate (EMS). The effect of chemical mutagenesis on metal concentration in and extraction by new sunflower M1 and M2 mutants was directly assessed on a metal-contaminated field in Raft, Switzerland. Mutants of the M2 generation showed a 2-3 times higher metal shoot concentration than the control plants. The best M2 sunflower "giant mutant" 14/185/04 showed a significantly enhanced metal extraction ability: 7.5 times for Cd, 9.2 times for Zn, and 8.2 times for Pb in aboveground parts, as compared to the control plants. Theoretical calculations for the phytoextraction potential of new sunflower variants note that the best sunflower mutant can produce up to 26 t dry matter per hectare and remove 13.3 kg Zn per hectare and year at the sewage sludge contaminated site of Raft; that is a gain factor of 9 compared to Zn extraction by sunflower controls. Furthermore, the use of sunflower oil and biomass for technical purposes (lubricants, biodiesel, biogas) should produce an additional value and improve the economical balance of phytoextraction.

  10. Chemical composition, functional and pasting properties of cassava starch and soy protein concentrate blends.

    Science.gov (United States)

    Chinma, Chiemela Enyinnaya; Ariahu, Charles Chukwuma; Abu, Joseph Oneh

    2013-12-01

    The chemical, functional and pasting properties of cassava starch and soy protein concentrate blends intended for biofilm processing were studied. Cassava starch and soy protein concentrates were prepared and mixed at different proportions (100: 0%; 90 : 10%; 80 : 20%; 70 : 30%; 60;40% and 50: 50%). Addition of varying levels of soy protein concentrates to cassava starch led to increases in moisture (from 7.10 to 9.17%), protein ( from 0.32 to 79.03%), ash (from 0.45 to 2.67%) and fat (from 0.17 to 0.98%) contents while crude fiber, carbohydrate and amylose contents decreased from ( 1.19 to 0.38%, 90.77 to 57.01% and 29.45 to 23.04%) respectively . Water absorption capacity and swelling power of cassava starch were improved as a result of soy protein concentrate addition while syneresis and solubility value of composite blends were lower than 100% cassava starch. In general, cassava-soy protein concentrate blends formed firmer gels than cassava starch alone. There were significant (p ≤ 0.05) increases in peak viscosity (from 160.12 to 268.32RVU), final viscosity (from 140.41 to 211.08RVU) and pasting temperature (from 71.00 to 72.32 °C ) of cassava starch due to addition of soy protein concentrate. These results suggest that the addition of soy protein concentrate to cassava starch affected the studied functional properties of cassava starch as evidenced by changes such as reduced syneresis, and solubility that are desirable when considering this biopolymer as an edible biofilm.

  11. Contaminant and nutrient concentrations of natural ingredient rat and mouse diet used in chemical toxicology studies.

    Science.gov (United States)

    Rao, G N; Knapka, J J

    1987-08-01

    The NIH-07 open formula natural ingredient rat and mouse ration is the standard diet for chemical toxicity and carcinogenicity studies conducted for the National Toxicology Program (NTP). Contaminant and nutrient concentrations were determined in 2 to 94 lots of this diet used in the NTP toxicology studies. All nutrient concentrations were equivalent to or greater than the requirements for rats and mice as set forth by the National Research Council. Aflatoxins, Hg, chlorinated hydrocarbons except methoxychlor, organophosphates except malathion, estrogenic activity, and Salmonella sp. were not present at the detectable levels. Fluorine, As, Cd, Pb, Se, N-nitrosodimethylamine, N-nitrosopyrrolidine, N-nitrosomorpholine, nitrate, nitrite, butylated hydroxyanisole, butylated hydroxytoluene, ethylene dibromide, methoxychlor, malathion, and trypsin inhibitor activity were present at or above the detectable levels. Five lots of diet had nitrosamine content of 100 to 273 ppb and 7 lots had 2.08 to 3.37 ppm of Pb. All other lots of NIH-07 diet used for NTP toxicology studies contained low levels of the contaminants. After determination of the contaminant concentrations in the 94 lots of diet and the contaminant concentrations in natural ingredients used in formulating NIH-07 diet, maximum allowable levels of contaminants were established and a flexible scoring system for acceptability of each lot of diet for chemical toxicology studies was developed. By prescreening ingredients such as fish meal for heavy metals and nitrosamines, and applying the flexible scoring system proposed, more than 95% of the lots of NIH-07 diet produced during the last 3 years had scores of greater than or equal to 95 out of 100 points and were considered acceptable for toxicology studies.

  12. Influence of Chemical Oxygen Demand Concentrations on Anaerobi Ammonium Oxidation by Granular Sludge From EGSB Reactor

    Institute of Scientific and Technical Information of China (English)

    JING KANG; JIAN-LONG WANG

    2006-01-01

    Objective To investigate the effect of chemical oxygen demand (COD) concentrations on the anaerobic ammonium oxidation (ANAMMOX). Methods An Expanded Granular Sludge Bed (EGSB) reactor was used to cultivate the granular sludge and to perform the ANAMMOX reaction in the bench scale experiment. NH4+-N and NO2--N were measured by usingcolorimetric method. NO3--N was analyzed by using the UV spectrophotometric method. COD measurement was based on digestion with potassium dichromate in concentrated sulphuric acid. Results When the COD concentrations in the reactors were 0 mg/L, 200 mg/L, 350 mg/L, and 550 mg/L, respectively, the NH4+-N removal efficiency was 12.5%, 14.2%, 14.3%, and 23.7%; the removal amount of NO2--N was almost the same; the nitrate removal efficiency was 16.8%, 94.5%, 86.6%, and 84.2% and TN removal efficiency was 16.3%, 50.7%, 46.9%, and 50.4%, moreover, the COD removal efficiency concentrations have a significant influence on anaerobic ammonium oxidation by granular sludge.

  13. Kinetics and Modeling of Chemical Leaching of Sphalerite Concentrate Using Ferric Iron in a Redox-controlled Reactor

    Institute of Scientific and Technical Information of China (English)

    宋健; 高玲; 林建群; 吴洪斌; 林建强

    2013-01-01

    This work presents a study for chemical leaching of sphalerite concentrate under various constant Fe3+concentrations and redox potential conditions. The effects of Fe3+ concentration and redox potential on chemical leaching of sphalerite were investigated. The shrinking core model was applied to analyze the experimental results. It was found that both the Fe3+ concentration and the redox potential controlled the chemical leaching rate of sphalerite. A new kinetic model was developed, in which the chemical leaching rate of sphalerite was proportional to Fe3+concentration and Fe3+/Fe2+ratio. All the model parameters were evaluated from the experimental data. The model predictions fit well with the experimental observed values.

  14. Prediction of aqueous solubility, vapor pressure and critical micelle concentration for aquatic partitioning of perfluorinated chemicals.

    Science.gov (United States)

    Bhhatarai, Barun; Gramatica, Paola

    2011-10-01

    The majority of perfluorinated chemicals (PFCs) are of increasing risk to biota and environment due to their physicochemical stability, wide transport in the environment and difficulty in biodegradation. It is necessary to identify and prioritize these harmful PFCs and to characterize their physicochemical properties that govern the solubility, distribution and fate of these chemicals in an aquatic ecosystem. Therefore, available experimental data (10-35 compounds) of three important properties: aqueous solubility (AqS), vapor pressure (VP) and critical micelle concentration (CMC) on per- and polyfluorinated compounds were collected for quantitative structure-property relationship (QSPR) modeling. Simple and robust models based on theoretical molecular descriptors were developed and externally validated for predictivity. Model predictions on selected PFCs were compared with available experimental data and other published in silico predictions. The structural applicability domains (AD) of the models were verified on a bigger data set of 221 compounds. The predicted properties of the chemicals that are within the AD, are reliable, and they help to reduce the wide data gap that exists. Moreover, the predictions of AqS, VP, and CMC of most common PFCs were evaluated to understand the aquatic partitioning and to derive a relation with the available experimental data of bioconcentration factor (BCF).

  15. Influence of Different Types and Concentrations of Chemical Catalysts on Dental Bleaching Efficiency.

    Science.gov (United States)

    Rocha Gomes Torres, Carlos; Guimarães, Carolina Anne; Ribeiro, Zulene Eveline Abreu; Borges, Alessandra Bühler

    2015-11-01

    The objective of this study was to evaluate the effects of different types and concentrations of chemical catalysts on the efficiency of 35% hydrogen peroxide gel on dental bleaching. Enamel-dentin disks were obtained from bovine incisors and the initial color was assessed. The groups were divided according to the type and concentration of catalyst added to an experimental gel: ferrous sulphate (FS) (0.001, 0.002 and 0.003%); ferrous gluconate (Fg) (0.01, 0.02 and 0.03%); ferric chloride (FC) (0.01, 0.02 and 0.03%); manganese gluconate (MG) (0.01, 0.02 and 0.03%); and manganese chloride (MC) (0.01, 0.02 and 0.03%). The positive control (PC) group received the bleaching gel without any catalyst, while in the negative control (NC) the specimens remained in artificial saliva. Three applications of the bleaching gels were performed for 10 minutes each, repeated after 7 days. Color assessments were performed 7 days after the first session and 7 days after the second. The specimens were stored in artificial saliva and assessed again after 1 year. The data were analyzed by parametric analysis of variance and Tukey's test. Some of the chemical catalysts tested were effective in reducing the yellowish color of the samples in relation to the positive control group after 1 and 2 applications and diminished the color relapse over time. After 1 year, the FS was the most effective catalyst tested. We concluded that some chemical catalysts increased the efficiency of dental bleaching.

  16. Ozone pollution in China: A review of concentrations, meteorological influences, chemical precursors, and effects.

    Science.gov (United States)

    Wang, Tao; Xue, Likun; Brimblecombe, Peter; Lam, Yun Fat; Li, Li; Zhang, Li

    2017-01-01

    High concentrations of ozone in urban and industrial regions worldwide have long been a major air quality issue. With the rapid increase in fossil fuel consumption in China over the past three decades, the emission of chemical precursors to ozone-nitrogen oxides and volatile organic compounds-has increased sharply, surpassing that of North America and Europe and raising concerns about worsening ozone pollution in China. Historically, research and control have prioritized acid rain, particulate matter, and more recently fine particulate matter (PM2.5). In contrast, less is known about ozone pollution, partly due to a lack of monitoring of atmospheric ozone and its precursors until recently. This review summarizes the main findings from published papers on the characteristics and sources and processes of ozone and ozone precursors in the boundary layer of urban and rural areas of China, including concentration levels, seasonal variation, meteorology conducive to photochemistry and pollution transport, key production and loss processes, ozone dependence on nitrogen oxides and volatile organic compounds, and the effects of ozone on crops and human health. Ozone concentrations exceeding the ambient air quality standard by 100-200% have been observed in China's major urban centers such as Jing-Jin-Ji, the Yangtze River delta, and the Pearl River delta, and limited studies suggest harmful effect of ozone on human health and agricultural corps; key chemical precursors and meteorological conditions conductive to ozone pollution have been investigated, and inter-city/region transport of ozone is significant. Several recommendations are given for future research and policy development on ground-level ozone.

  17. Analytical quality in environmental studies: uncertainty evaluation of chemical concentrations determined by INAA

    Directory of Open Access Journals (Sweden)

    Elvis Joacir de França

    2006-01-01

    Full Text Available Instrumental neutron activation analysis (INAA is a measurement technique of high metrological level for the determination of chemical elements. In the context of BIOTA/FAPESP Program, leaves of trees have been evaluated by INAA for biomonitoring purposes of the Atlantic Forest. To assure the comparability of results in environmental studies, a leaf sample of Marlierea tomentosa (Myrtaceae family showing the lowest concentrations of chemical elements was selected for the evaluation of analytical quality of the determination under unfavorable conditions. Nevertheless, the homogeneity of chemical concentrations of sample at the 95% of confidence level has been achieved and INAA has presented repeatability of 2% for the determination of Br, Co, Cs, Fe, K, Na, Rb and Sr, the uncertainty could have been overestimated. For the evaluation of uncertainty due to the variability of chemical concentrations in the sample, Jackknife and Bootstrap methods were used to estimate the maximum expected percent standard deviation. The uncertainty budget was considered adequate for the reporting chemical concentrations of environmental samples determined by INAA.A análise por ativação neutrônica instrumental (INAA é uma técnica analítica de alto nível metrológico para a determinação de elementos químicos. No contexto do programa BIOTA/FAPESP, folhas de árvores vêm sendo avaliadas empregando-se INAA para a biomonitoração da Mata Atlântica. Para garantir a comparabilidade dos resultados em estudos ambientais, amostra de folhas de Marlierea tomentosa, cujas concentrações de elementos químicos obtidas foram as menores, foi selecionada para a avaliação da qualidade analítica na mais desfavorável situação. Esta avaliação levou em consideração a homogeneidade das concentrações de elementos e a estimativa da repetitividade analítica. Embora a homogeneidade das concentrações tenha sido detectada em nível de 95% de confiança e a INAA tenha

  18. Biodegradation of PAHs in soil: Influence of chemical structure, concentration and multiple amendment

    Energy Technology Data Exchange (ETDEWEB)

    Couling, Natalie R.; Towell, Marcie G. [Lancaster Environment Centre, Lancaster University, Lancaster LA1 4YQ (United Kingdom); Semple, Kirk T., E-mail: k.semple@lancaster.ac.u [Lancaster Environment Centre, Lancaster University, Lancaster LA1 4YQ (United Kingdom)

    2010-11-15

    The influence of PAH chemical structure and concentration, added in either single (75 or 300 mg kg{sup -1}) or multiple (2 x 75, 2 x 150 or 4 x 75 mg kg{sup -1}) applications as single- or multiple-contaminant systems, on the development of PAH biodegradation in a pristine soil was investigated. Development in microbial catabolic ability was assessed at 0, 28, 56 and 84 d by monitoring {sup 14}C-naphthalene, {sup 14}C-phenanthrene and {sup 14}C-pyrene mineralisation over 14 d in respirometric assays. The presence of other contaminants influenced the ability of the indigenous microflora to mineralise structurally different contaminants over time. {sup 14}C-Naphthalene mineralisation was inhibited by the presence of other contaminants; whereas the presence of naphthalene significantly enhanced rates of mineralisation in multiple-contaminant systems containing {sup 14}C-phenanthrene and {sup 14}C-pyrene. Generally, increasing the number of contaminant applications has implications for catabolic activity of soil microbes. It is suggested the toxic nature of PAHs retarded mineralisation at increased contaminant concentrations. - The simultaneous effects of PAH concentration, contaminant mixture and repeated application on the development of catabolic activity in soil.

  19. Optimal voxel size for measuring global gray and white matter proton metabolite concentrations using chemical shift imaging

    DEFF Research Database (Denmark)

    Hanson, Lars Peter Grüner; Adalsteinsson, E; Pfefferbaum, A;

    2000-01-01

    Quantification of gray and white matter levels of spectroscopically visible metabolites can provide important insights into brain development and pathological conditions. Chemical shift imaging offers a gain in efficiency for estimation of global gray and white matter metabolite concentrations...

  20. Determining airborne concentrations of spatial repellent chemicals in mosquito behavior assay systems.

    Directory of Open Access Journals (Sweden)

    Nicholas J Martin

    Full Text Available BACKGROUND: Mosquito behavior assays have been used to evaluate the efficacy of vector control interventions to include spatial repellents (SR. Current analytical methods are not optimized to determine short duration concentrations of SR active ingredients (AI in air spaces during entomological evaluations. The aim of this study was to expand on our previous research to further validate a novel air sampling method to detect and quantitate airborne concentrations of a SR under laboratory and field conditions. METHODOLOGY/PRINCIPAL FINDINGS: A thermal desorption (TD gas chromatography-mass spectrometry (GC-MS method was used to determine the amount of dichlorodiphenyltrichloroethane (DDT in samples of air. During laboratory experiments, 1 L volumes of air were collected over 10 min intervals from a three-chamber mosquito behavior assay system. Significantly higher levels of airborne DDT were measured in the chamber containing textiles treated with DDT compared to chambers free of AI. In the field, 57 samples of air were collected from experimental huts with and without DDT for onsite analysis. Airborne DDT was detected in samples collected from treated huts. The mean DDT air concentrations in these two huts over a period of four days with variable ambient temperature were 0.74 µg/m(3 (n = 17; SD = 0.45 and 1.42 µg/m(3 (n = 30; SD = 0.96. CONCLUSIONS/SIGNIFICANCE: The results from laboratory experiments confirmed that significantly different DDT exposure conditions existed in the three-chamber system establishing a chemical gradient to evaluate mosquito deterrency. The TD GC-MS method addresses a need to measure short-term (<1 h SR concentrations in small volume (<100 L samples of air and should be considered for standard evaluation of airborne AI levels in mosquito behavior assay systems. Future studies include the use of TD GC-MS to measure other semi-volatile vector control compounds.

  1. Antiscalant removal in accelerated desupersaturation of RO concentrate via chemically-enhanced seeded precipitation (CESP).

    Science.gov (United States)

    McCool, Brian C; Rahardianto, Anditya; Cohen, Yoram

    2012-09-01

    An experimental study was carried out to demonstrate and quantify the feasibility of antiscalant (AS) removal from brackish water RO concentrate of high gypsum scaling propensity via lime treatment prior to seeded gypsum precipitation. Based on studies with model solutions, it was shown that sufficient AS removal (up to ∼90%) from RO concentrate is feasible via a lime treatment step (at a dose significantly lower than that required for conventional lime softening) to enable effective subsequent seeded gypsum precipitation. This two-step chemically-enhanced seeded precipitation (CESP) treatment of primary RO concentrate is suitable as an intermediate concentrate demineralization (ICD) stage for high recovery desalting employing secondary RO desalination. Analysis of gypsum precipitation and lime treatment kinetic data suggests that, after adequate CaCO(3) precipitation has been induced for effective AS scavenging, CaSO(4) desupersaturation can be achieved via seeded gypsum precipitation without retardation due to seed poisoning by AS. Also, the lime dose required to prevent seed poisoning during subsequent gypsum desupersaturation via seeded gypsum precipitation can be adequately assessed with a precipitation kinetics model that considers AS seed poisoning based on a Langmuir adsorption isotherm. The degree of AS removal after lime treatment increased linearly with the logarithm of the single lime dose additions. Staged lime dosing (i.e., multiple lime additions), however, removed a higher degree of AS relative to an equivalent single lime dose addition since a higher driving force for CaCO(3) precipitation could be maintained over the course of the lime treatment period.

  2. Low-concentration chemical sensing using surface-enhanced coherent anti-Stokes Raman spectroscopy

    Science.gov (United States)

    Hua, Xia; Sinyukov, Alexander; Traverso, Andrew; Veronine, Dmitri; Wang, Kai; Xia, Hui; Yang, Wenlong; Yuan, Luqi; Sokolov, Alexei; Scully, Marlan

    2010-10-01

    Measurements of surface enhanced coherent anti-Stokes Raman spectra (CARS) of cyclohexane are carried out. Random aggregates of gold nanoparticles for field enhancement were deposited on a glass substrate and were characterized using atomic force microscopy (AFM). Surface enhancement of the CARS signal by gold nanoparticles is observed. This technique can be used to detect low amounts of chemicals with a higher sensitivity compared to the conventional surface-enhanced Raman spectroscopy (SERS). The lowest detected concentration of cyclohexane in a thin film of methanol was 1%. However, it was not possible to detect any signal from the same sample of cyclohexane without gold nanoparticles using conventional CARS technique. Therefore, surface enhancement is necessary to achieve higher spectroscopy sensitivity. Further studies of nanostructure-enhanced electrical fields are required to quantitatively understand the observed effects and will be performed in the future.

  3. Morphology, chemical composition, and bacterial concentration of airborne particulate matter in rabbit farms

    Directory of Open Access Journals (Sweden)

    Elisa Adell

    2012-12-01

    Full Text Available Livestock houses are major sources of airborne particulate matter (PM, which can originate from manure, feed, feathers, skin and bedding and may contain and transport microorganisms. Improved knowledge of particle size, morphology, chemical and microbiological composition of PM in livestock houses can help identify major sources of PM and contribute to the development of appropriate source-specific reduction techniques. In rabbit production systems, however, there is limited information on specific particle characteristics. The objective of this study was to characterise airborne PM in rabbit farms in terms of morphology, chemical compositions and bacterial concentration in different size fractions. Size-fractioned PM was sampled in the air of 2 rabbit farms, 1 for fattening rabbits and 1 for reproductive does, using a virtual cascade impactor, which simultaneously collected total suspended PM (TSP, PM10 and PM2.5 size fractions. Airborne PM samples were examined by light microscopy and scanning electron microscopy combined with energy dispersive X-ray analysis. Representative samples from potential sources of PM were also collected and examined. Additionally, a methodology to extract bacteria from the collected samples of airborne PM was developed to determine the bacterial concentration per PM size fraction. Results showed that airborne PM in rabbit farms is highly complex in particle morphology, especially in size. Broken skin flakes, disintegrated particles from feed or faecal material from mechanical fracture are the main sources of airborne PM in rabbit farms. Major elements found in rabbit airborne PM were S, Ca, Mg, Na and Cl. Bacterial concentrations ranged from 1.7×104 to 1.6×106 colony forming units (CFU/m3 (TSP; from 3.6×103 to 3.0×104 CFU/m3 (PM10; and from 3.1×103 to 1.6×104 CFU/m3 (PM2.5. Our results will improve the knowledge on essential particle characteristics necessary to understand PM’s origin in rabbit farms and

  4. Sampling and analysis of chemical element concentration distribution in rock units and orebodies

    Directory of Open Access Journals (Sweden)

    F. P. Agterberg

    2012-01-01

    Full Text Available Existing sampling techniques applied within known orebodies, such as sampling along mining drifts, yield element concentration values for larger blocks of ore if they are extended into their surroundings. The resulting average concentration values have relatively small "extension variance". These techniques can be used for multifractal modeling as well as ore reserve estimation approaches. Geometric probability theory can aid in local spatial covariance modeling. It provides information about increase of variability of element concentration over short distances exceeding microscopic scale. In general, the local clustering of ore crystals results in small-scale variability known as the "nugget effect". Parameters to characterize spatial covariance estimated from ore samples subjected to chemical analysis for ore reserve estimation may not be valid at local scale because of the nugget effect. The novel method of local singularity mapping applied within orebodies provides new insights into the nature of the nugget effect. Within the Pulacayo orebody, Bolivia, local singularity for zinc is linearly related with logarithmically transformed concentration value. If there is a nugget effect, moving averages resulting from covariance models or estimated by other methods that have a smoothing effect, such as kriging, can be improved by incorporating local singularities indicating local element enrichment or depletion. Although there have been many successful applications of the multifractal binomial/p model, its application within the Pulacayo orebody results in inconsistencies, indicating some shortcomings of this relatively simple approach. Local singularity analysis and universal multifractal modeling are two promising new approaches to improve upon results obtained by commonly used geostatistical techniques and use of the binomial/p model. All methods in this paper are illustrated using a single example (118 Pulacayo zinc values, and

  5. Concentration of 'forgotten' substances using the XAD concentration method. Suitability of the method for hydrophilic chemicals

    NARCIS (Netherlands)

    Collombon MT; LER

    2007-01-01

    Concentrering van 'vergeten' stoffen met gebruikmaking van de XAD-concentreringsmethode In de jaren '90 is door het RIVM een methode ontwikkeld om toxische stoffen uit oppervlaktewater te concentreren op XAD (een chemische hars). In het concentraat kan de toxiciteit worden bepaald

  6. Development, chemical and sensory characterization of semi skim yogurt added with whey protein concentrate

    Directory of Open Access Journals (Sweden)

    Andressa Regina Antunes

    2015-04-01

    Full Text Available The aim of this work was to develop, to perform the chemical characterization and verify the acceptability of a semi skim yogurt added with whey protein concentrate (WPC 35 %, and compare it to traditional yogurt, without adding any protein source. For this, two formulations were prepared: 1- traditional semi skim and 2: semi skim added with WPC 35 %, with subsequent evaluation of physicochemical characteristics of acidity, pH and viscosity, as well as the compositional analysis of the levels of humidity, full solids, ash, protein, fat and carbohydrates for both formulations. The sensory analysis was performed with 80 untrained tasters, which was based on parameters of appearance, taste, flavor and consistency. The appearance and consistency parameters showed a significant difference between received grades, and the yogurt added with WPC 35 % the most preferred these aspects, as well as the formulation with the highest widespread acceptance among testers. The results indicate that the use of WPC 35 % in foods is a promising alternative, considering the overall acceptance obtained, the protein content beneficial to the consumers health, the improvement of technological properties provided to food coupled to the extent which it is produced, low cost and reducing the damage caused to the environment. 

  7. Chemical effects of a high CO2 concentration in oxy-fuel combustion of methane

    DEFF Research Database (Denmark)

    Glarborg, Peter; Bentzen, L.L.B.

    2008-01-01

    in terms of a detailed chemical kinetic mechanism for hydrocarbon oxidation. On the basis of results of the present study, it can be expected that oxy-fuel combustion will lead to strongly increased CO concentrations in the near-burner region. The CO2 present will compete with O-2 for atomic hydrogen......The oxidation of methane in an atmospheric-pres sure flow reactor has been studied experimentally under highly diluted conditions in N-2 and CO2, respectively. The stoichiometry was varied from fuel-lean to fuel-rich, and the temperatures covered the range 1200-1800 K. The results were interpreted...... and lead to formation of CO through the reaction CO2 + H reversible arrow CO + OH. Reactions of CO2 with hydrocarbon radicals may also contribute to CO formation. The most important steps are those of singlet and triplet CH2 with CO2, while other radicals such as CH3 and CH are less important for consuming...

  8. [Physical, chemical and microbiological quality of concentrated orange juices made in Venezuela].

    Science.gov (United States)

    Cava, R M; Hernández, P

    1996-03-01

    Concentrated fruit juices are a very attractive type of product because of the many advantages they offer for reductions in packing, transportation and storage costs, and in addition, they offer the possibility of consumption outside harvesting time. Due to their potential in the international market, it is necessary to evaluate if they are accomplishing the quality requirements, and to know the different factors that can affect their stability. For this purpose, samples of national products were analyzed for physical, chemical and microbiological characteristics; the diacetyl test was performed as a measure of the sanitary conditions under processing. The samples analyzed comply with the national standards established by the Comision Venezolana de Normas Industriales (COVENIN N(o) 2395-86 Concentrados de frutas para consumo directo). It is advisable to determine the zero tolerant yeasts population because this type of microorganisms are responsible for spoilage whenever cold storage is interrupted, and because they can not be detected by the official procedures used to detect yeasts.

  9. Investigation into the Effect of Concentration of Benzotriazole on the Selective Layer Surface in the Chemical Mechanical Planarization Process

    Science.gov (United States)

    Ilie, Filip; Laurian, Tiberiu

    2015-12-01

    During selective layer chemical mechanical planarization (CMP), the surface layer is selectively oxidized and removed. Material removal rate in selective layer CMP depends on the depth of removal, pH of the solution, slurry chemistry, potential, percentage of oxidizer, and the applied load. Benzotriazole (BTA) has been used as a corrosion inhibitor in the CMP process. The role of BTA is to prevent corrosion of a pattern via a chemical reaction that forms a Cu-BTA passive film on the selective-layer surface. This paper focuses on the concentration effect of BTA in the slurry of a selective layer CMP process by measuring the friction force during CMP and the modification of the selective layer films immersed in slurries containing various concentrations of BTA. Additionally; the friction characteristics with the concentration of BTA in the selective layer CMP slurry. The effect of BTA concentration was verified using an empirical model based on the friction energy ( E f).

  10. Sorption kinetics and microbial biodegradation activity of hydrophobic chemicals in sewage sludge: Model and measurements based on free concentrations

    NARCIS (Netherlands)

    Artola-Garicano, E.; Borkent, I.; Damen, K.; Jager, T.; Vaes, W.H.J.

    2003-01-01

    In the current study, a new method is introduced with which the rate-limiting factor of biodegradation processes of hydrophobic chemicals in organic and aqueous systems can be determined. The novelty of this approach lies in the combination of a free concentration-based kinetic model with measuremen

  11. CHEMICAL DETERMINATION OF HEAVY METALS IN PB AND ZN CONCENTRATES OF TREPÇA (KOSOVO AND CORRELATIONS COEFFI CIENTS STUDY BETWEEN CHEMICAL DATA

    Directory of Open Access Journals (Sweden)

    Fatbardh Gashi

    2017-03-01

    Full Text Available Kosovo ore deposits are located in the Trepça belt which extends for over 80 km. The concentrate produced by the flotation process of the Trepça metallurgical corporation contains a considerable quantity of valuable metals, such as Pb, Zn, Fe and minor accompanying metals such as Cd, Cu, As, Sb, Bi, Ag, Au, etc. The subject of this work was to assess the concentration of major and minor metals in lead and zinc concentrates of Trepça and to study the correlation coefficients between metals. Chemical determination of concentrates was performed by using atomic absorption spectroscopy (AAS. In the content on lead concentrate samples, the following were found: Pb>Fe>Zn> Ag> As>Sb>Cd. In the content of zinc concentrate, the following were found: Zn>Fe>Pb>Ag>As>Cd. The program “Statistica ver. 6.0” has been used for calculations of basic statistical parameters, relationships between data and cluster analysis of R-mode. R-mode cluster analysis on lead concentrate samples showed that Pb has the closest linkages with Fe and they form one branch of the dendogram. On the zinc concentrate samples, Zn has the closest linkages with Fe and they form one branch of the dendogram.

  12. Concentration levels of endocrine disrupting chemicals in environmental media of Korea

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, Junheon; Choi, Kyunghee; Kim, Sangdon; Kim, Eunji; Kim, Eunkyoung; Jeon, Sung-Hwan; Na, Jin-Gyun [National Institute of Environmental Research, Incheon (Korea)

    2004-09-15

    Introduction As the public is more concerned about endocrine disrupting chemicals (EDCs), the Ministry of Environment in Korea has designed and established a mid- and long-term research plan on EDCs. Since 1999, the National Institute of Environmental Research has investigated the impact of EDCs on the natural ecosystem and carried out the field test for environmental monitoring. The goal of this study was to measure the contamination level of EDCs in a variety of environmental media, such as water, sediment, soil and air and to provide a basis for the sound management of EDCs and policy-making for the control of EDCs in Korea. Environmental monitoring sites were selected at representative sites through the nation. In 2002, 310 samples were collected from 122 sites of water, sediment, soil and air. The target EDCs examined were 93 chemicals in 45 chemical groups including Dioxin, coplanar PCBs, PCBs. Results show that 46 chemicals (31 chemical groups) including dioxins were detected in at least one environmental medium, while 47 chemicals including aldrin were not detected in any environmental media. In this study, the results of the fourth year of environmental monitoring are reported.

  13. Trace metal concentrations in acidic, headwater streams in Sweden explained by chemical, climatic, and land use variations

    Directory of Open Access Journals (Sweden)

    B. J. Huser

    2012-02-01

    Full Text Available Long term data series (1996–2009 for eleven acidic, headwater streams (<10 km2 in Sweden were analyzed to determine factors controlling concentrations of trace metals. In-stream chemical data as well climatic, flow, and deposition chemistry data were used to develop models predicting concentrations of chromium (Cr, lead (Pb, and zinc (Zn. Data were initially analyzed using partial least squares to determine a set of variables that could predict metal concentrations across all sites. Organic matter (as absorbance and iron related positively to Pb and Cr while pH related negatively to Pb and Zn. Other variables such as conductivity, manganese, and temperature were important as well. Multiple linear regression was then used to determine minimally adequate prediction models which explained an average of 35% (Cr, 52% (Zn, and 72% (Pb of metal variation across all sites. While models explained at least 50% of variation in the majority of sites for Pb (10 and Zn (8, only three sites met this criterion for Cr. Investigation of variation between site models for each metal revealed geographical (altitude, chemical (sulfate, and land use (silvaculture influences on predictive power of the models. Residual analysis revealed seasonal differences in the ability of the models to predict metal concentrations as well. Expected future changes in model variables were applied and results showed the potential for long term increases (Pb or decreases (Zn for trace metal concentrations at these sites.

  14. Lead, zinc, and chromium concentrations in acidic headwater streams in Sweden explained by chemical, climatic, and land-use variations

    Directory of Open Access Journals (Sweden)

    B. J. Huser

    2012-11-01

    Full Text Available Long-term data series (1996–2009 for eleven acidic headwater streams (< 10 km2 in Sweden were analyzed to determine factors controlling concentrations of trace metals. In-stream chemical data as well climatic, flow, and deposition chemistry data were used to develop models predicting concentrations of chromium (Cr, lead (Pb, and zinc (Zn. Data were initially analyzed using partial least squares to determine a set of variables that could predict metal concentrations across all sites. Organic matter (as absorbance and iron related positively to Pb and Cr, while pH related negatively to Pb and Zn. Other variables such as conductivity, manganese, and temperature were important as well. Multiple linear regression was then used to determine minimally adequate prediction models which explained an average of 35% (Cr, 52% (Zn, and 72% (Pb of metal variation across all sites. While models explained at least 50% of variation in the majority of sites for Pb (10 and Zn (8, only three sites met this criterion for Cr. Investigation of variation between site models for each metal revealed geographical (altitude, chemical (sulfate, and land-use (silvaculture influences on predictive power of the models. Residual analysis revealed seasonal differences in the ability of the models to predict metal concentrations as well. Expected future changes in model variables were applied and results showed the potential for long-term increases (Pb or decreases (Zn for trace metal concentrations at these sites.

  15. Organic and nitrogen fertilization of soil under Syrah grapevine: effects on soil chemical properties and nitrate concentration.

    OpenAIRE

    Davi José Silva; Luís Henrique Bassoi; Marlon Gomes da Rocha; Alexsandro Oliveira da Silva; Magnus Dall’Igna Deon

    2016-01-01

    ABSTRACT Viticulture is an activity of great social and economic importance in the lower-middle region of the São Francisco River valley in northeastern Brazil. In this region, the fertility of soils under vineyards is generally poor. To assess the effects of organic and nitrogen fertilization on chemical properties and nitrate concentrations in an Argissolo Vermelho-Amarelo (Typic Plinthustalf), a field experiment was carried out in Petrolina, Pernambuco, on Syrah grapevines. Treatments cons...

  16. Organic and Nitrogen Fertilization of Soil under ‘Syrah’ Grapevine: Effects on Soil Chemical Properties and Nitrate Concentration

    OpenAIRE

    Silva,Davi José; Bassoi,Luís Henrique; Rocha,Marlon Gomes da; Silva, Alexsandro Oliveira da [UNESP; Deon,Magnus Dall'Igna

    2016-01-01

    ABSTRACT Viticulture is an activity of great social and economic importance in the lower-middle region of the São Francisco River valley in northeastern Brazil. In this region, the fertility of soils under vineyards is generally poor. To assess the effects of organic and nitrogen fertilization on chemical properties and nitrate concentrations in an Argissolo Vermelho-Amarelo (Typic Plinthustalf), a field experiment was carried out in Petrolina, Pernambuco, on Syrah grapevines. Treatments cons...

  17. Concentrations of Chemical Elements in Willow Biomass Depend on Clone, Site and Management in the Field

    DEFF Research Database (Denmark)

    Liu, Na; Jørgensen, Uffe; Lærke, Poul Erik

    2016-01-01

    Eight willow (Salix) clones (Inger, Klara, Linnea, Resolution, Stina, Terra Nova, Tora, Tordis) were planted on two soil types in Denmark. The biomass quality was evaluated after 3 years of growth by measuring differences in concentrations of 14 elements associated with ash behavior during...... to 22, 27, 35, and 23 % higher concentrations of K, S, Ca, and total ash than the other clones. In addition to clone and site, appropriate management could further improve the fuel quality of willow biomass. When shoots of Inger were harvested annually (1-year shoots) high concentrations of K and Cl...... plant densities (8000 and 12,000 trees ha−1) of the clones Inger and Tora after the first 3-year rotation when grown at the site with a coarse sandy soil. The study indicates considerable diversity in concentration of elements within commercially available willow cultivars and suggests breeders...

  18. Chemical and functional properties of fibre concentrates obtained from by-products of coconut kernel.

    Science.gov (United States)

    Yalegama, L L W C; Nedra Karunaratne, D; Sivakanesan, Ramiah; Jayasekara, Chitrangani

    2013-11-01

    The coconut kernel residues obtained after extraction of coconut milk (MR) and virgin coconut oil (VOR) were analysed for their potential as dietary fibres. VOR was defatted and treated chemically using three solvent systems to isolate coconut cell wall polysaccharides (CCWP). Nutritional composition of VOR, MR and CCWPs indicated that crude fibre, neutral detergent fibre, acid detergent fibre and hemicelluloses contents were higher in CCWPs than in VOR and MR. MR contained a notably higher content of fat than VOR and CCWPs. The oil holding capacity, water holding capacity and swelling capacity were also higher in CCWPs than in VOR and MR. All the isolates and MR and VOR had high metal binding capacities. The CCWPs when compared with commercially available fibre isolates, indicated improved dietary fibre properties. These results show that chemical treatment of coconut kernel by-products can enhance the performance of dietary fibre to yield a better product.

  19. Concept Studies of Micro-Pump for Chemical Concentration in Handheld Micro Sensors

    Science.gov (United States)

    2007-11-02

    This report summarizes the preliminary results of a short-term innovative research project on the concept study of micro pumps for chemical...main objective of the work is to study the feasibility of certain micro pumping concepts and their potential integration with the sensing material and... micro pumps is demonstrated, although the quantitative assessment of the pumping system is still elusive, partly because of lack of specifications. The

  20. Chemical concentrations and instantaneous loads, Green River to the Lower Duwamish Waterway near Seattle, Washington, 2013–15

    Science.gov (United States)

    Conn, Kathleen E.; Black, Robert W.; Vanderpool-Kimura, Ann M.; Foreman, James R.; Peterson, Norman T.; Senter, Craig A.; Sissel, Stephen K.

    2015-12-23

    In November 2013, U.S. Geological Survey streamgaging equipment was installed at a historical water-quality station on the Duwamish River, Washington, within the tidal influence at river kilometer 16.7 (U.S. Geological Survey site 12113390; Duwamish River at Golf Course at Tukwila, WA). Publicly available, real-time continuous data includes river streamflow, stream velocity, and turbidity. Between November 2013 and March 2015, the U.S. Geological Survey collected representative samples of water, suspended sediment, or bed sediment from the streamgaging station during 28 periods of differing flow conditions. Samples were analyzed by Washington-State-accredited laboratories for a large suite of compounds, including metals, dioxins/furans, semivolatile compounds including polycyclic aromatic hydrocarbons, pesticides, butytins, polychlorinated biphenyl (PCB) Aroclors and the 209 PCB congeners, volatile organic compounds, hexavalent chromium, and total and dissolved organic carbon. Metals, PCB congeners, and dioxins/furans were frequently detected in unfiltered-water samples, and concentrations typically increased with increasing suspended-sediment concentrations. Chemical concentrations in suspendedsediment samples were variable between sampling periods. The highest concentrations of many chemicals in suspended sediment were measured during summer and early autumn storm periods.

  1. Relaxation rate for an ultrafast folding protein is independent of chemical denaturant concentration.

    Science.gov (United States)

    Cellmer, Troy; Henry, Eric R; Kubelka, Jan; Hofrichter, James; Eaton, William A

    2007-11-28

    The connection between free-energy surfaces and chevron plots has been investigated in a laser temperature jump kinetic study of a small ultrafast folding protein, the 35-residue subdomain from the villin headpiece. Unlike all other proteins that have been studied so far, no measurable dependence of the unfolding/refolding relaxation rate on denaturant concentration was observed over a wide range of guanidinium chloride concentration. Analysis with a simple Ising-like theoretical model shows that this denaturant-invariant relaxation rate can be explained by a large movement of the major free energy barrier, together with a denaturant- and reaction coordinate-dependent diffusion coefficient.

  2. Field evaluation of a new particle concentrator- electrostatic precipitator system for measuring chemical and toxicological properties of particulate matter

    Directory of Open Access Journals (Sweden)

    Pakbin Payam

    2008-11-01

    Full Text Available Abstract Background A newly designed electrostatic precipitator (ESP in tandem with Versatile Aerosol Concentration Enrichment System (VACES was developed by the University of Southern California to collect ambient aerosols on substrates appropriate for chemical and toxicological analysis. The laboratory evaluation of this sampler is described in a previous paper. The main objective of this study was to evaluate the performance of the new VACES-ESP system in the field by comparing the chemical characteristics of the PM collected in the ESP to those of reference samplers operating in parallel. Results The field campaign was carried out in the period from August, 2007 to March, 2008 in a typical urban environment near downtown Los Angeles. Each sampling set was restricted to 2–3 hours to minimize possible sampling artifacts in the ESP. The results showed that particle penetration increases and ozone concentration decreases with increasing sampling flow rate, with highest particle penetration observed between 100 nm and 300 nm. A reference filter sampler was deployed in parallel to the ESP to collect concentration-enriched aerosols, and a MOUDI sampler was used to collect ambient aerosols. Chemical analysis results showed very good agreement between the ESP and MOUDI samplers in the concentrations of trace elements and inorganic ions. The overall organic compound content of PM collected by the ESP, including polycyclic aromatic hydrocarbons (PAHs, hopanes, steranes, and alkanes, was in good agreement with that of the reference sampler, with an average ESP -to -reference concentration ratio of 1.07 (± 0.38. While majority of organic compound ratios were close to 1, some of the semi-volatile organic species had slightly deviated ratios from 1, indicating the possibility of some sampling artifacts in the ESP due to reactions of PM with ozone and radicals generated from corona discharge, although positive and negative sampling artifacts in the

  3. Schiff base: A high affinity chemical agent to decrease the concentration of aflatoxin M1 in raw milk contaminated artificially

    Directory of Open Access Journals (Sweden)

    Frane Delaš

    2012-03-01

    Full Text Available In the present study were conducted the effect of pH (5.5, 6.0 and 6.5 and concentration of new synthesized 3-/2-aminophenylimino-(p-toluoyl/-4-hydroxy-6-(p-tolyl-2H-pyrane-2-one (Schiff base on decrease the concentration of aflatoxin M1 (AFM1 in raw milk contaminated with known concentration of this toxin. Experiments were carried out at temperature of 4 °C during 35 days. At pH 5.5 Schiff base concentration of 0.1 µmol/L was lessening the concentration of AFM1 after 35 days by 55 %. However, at pH 6.5 the most effective concentration for lessening of AFM1 was 0.5 µmol/L. Schiff base was not effective at pH value of 7 or higher. The ability of Schiff base to act as antimycotoxigenic agent provides new perspective for possibly using this compound to control AFM1 contamination in milk and to extent shelf lives of this food. Detection of toxicity of investigated Schiff base was performed by using the brine shrimp (Artemia salina larvae as an biological indicator to determine their sensitivity to this chemical agent.

  4. Physical and chemical changes in whey protein concentrate stored at elevated temperature and humidity

    Science.gov (United States)

    The chemistry of whey protein concentrate (WPC) under adverse storage conditions was monitored to provide information on shelf life in hot, humid areas. WPC34 (34.9 g protein/100 g) and WPC80 (76.8 g protein/100 g) were stored for up to 18 mo under ambient conditions and at elevated temperature and...

  5. Mixtures of chemical pollutants at European legislation safety concentrations: how safe are they?

    DEFF Research Database (Denmark)

    Carvalho, Raquel N.; Arukwe, Augustine; Ait-Aissa, Selim

    2014-01-01

    ) fish embryo toxicity, v) impaired frog embryo development, and vi) increased expression on oxidative stress-linked reporter genes. Estrogenic activity close to regulatory safety limit concentrations was uncovered by receptor-binding assays. The results highlight the need of precautionary actions...

  6. Characteristics of concentrations and chemical compositions for PM2.5 in the region of Beijing, Tianjin, and Hebei, China

    Directory of Open Access Journals (Sweden)

    W. Z. Zhang

    2013-01-01

    Full Text Available In order to study the temporal and spatial variations of PM2.5 and its chemical compositions in the region of Beijing, Tianjin, and Hebei (BTH, PM2.5 samples were collected at four urban sites in Beijing (BJ, Tianjin (TJ, Shijiazhuang (SJZ, and Chengde (CD and one site at Shangdianzi (SDZ regional background station over four seasons from 2009 to 2010. The samples were weighted for mass concentrations and analyzed in laboratory for chemical profiles of 19 elements (Al, As, Ba, Ca, Cd, Co, Cr, Cu, Fe, K, Mg, Mn, Ni, P, Pb, Sr, Ti, V, and Zn, eight water-soluble ions (Na+, NH4+, K+, Mg2+, Ca2+, Cl−, NO3−, and SO42−, and carbon fractions (OC and EC. The concentrations of PM2.5 and its major chemical species were season-dependent and showed spatially similar characteristics in the plain area of BTH. The average annual concentrations of PM2.5 were 71.8–191.2 μg m−3 at five sites, with more than 90 % sampling days exceeded 50 μg m−3 at BJ, TJ, and SJZ. PM2.5 pollution was most serious at SJZ, and the annual concentrations of PM2.5, secondary ions, OC, EC, and most of crustal elements were all highest. Due to stronger photochemical oxidation, the sum of concentrations of secondary ions (NH4+, NO3−, and SO42− was highest in the summer at SDZ, BJ, TJ, and CD. Analysis of electric charges of water-soluble ions indicated the existence of nitric acid or hydrochloric acid in PM2.5. For all five sites, the concentrations of OC, EC and also secondary organic carbon (SOC in the spring and summer were lower than those in the autumn and winter. Stable atmosphere and low temperatures appearing more frequently during autumn and winter facilitated the formation of SOC. The sums of crustal elements (Al, Ca, Fe, Mg, Ti, Ba, and Sr were higher in the spring and autumn owing to more days with blowing or floating dust. The concentrations of heavy metals were at higher levels in the BTH area by comparison with other studies. In Shijiazhuang and Chengde

  7. Characteristics of concentrations and chemical compositions for PM2.5 in the region of Beijing, Tianjin, and Hebei, China

    Science.gov (United States)

    Zhao, P. S.; Dong, F.; He, D.; Zhao, X. J.; Zhang, X. L.; Zhang, W. Z.; Yao, Q.; Liu, H. Y.

    2013-05-01

    In order to study the temporal and spatial variations of PM2.5 and its chemical compositions in the region of Beijing, Tianjin, and Hebei (BTH), PM2.5 samples were collected at four urban sites in Beijing (BJ), Tianjin (TJ), Shijiazhuang (SJZ), and Chengde (CD), and also one site at Shangdianzi (SDZ) regional background station over four seasons from 2009 to 2010. The samples were weighted for mass concentrations and analyzed in the laboratory for chemical profiles of 19 elements (Al, As, Ba, Ca, Cd, Co, Cr, Cu, Fe, K, Mg, Mn, Ni, P, Pb, Sr, Ti, V, and Zn), eight water-soluble inorganic ions (Na+, NH4+, K+, Mg2+, Ca2+, Cl-, NO3-, and SO42-, and carbon fractions (OC and EC). The concentrations of PM2.5 and its major chemical species were season dependent and showed spatially similar characteristics in the plain area of BTH. The average annual concentrations of PM2.5 were 71.8-191.2 μg m-3 at the five sites, with more than 90% of sampling days exceeding 50 μg m-3 at BJ, TJ, and SJZ. PM2.5 pollution was most serious at SJZ, and the annual concentrations of PM2.5, secondary inorganic ions, OC, EC, and most crustal elements were all highest. Due to stronger photochemical oxidation, the sum of concentrations of secondary inorganic ions (NH4+, NO3-, and SO42- was highest in the summer at SDZ, BJ, TJ, and CD. Analysis of electric charges of water-soluble inorganic ions indicated the existence of nitric acid or hydrochloric acid in PM2.5. For all five sites, the concentrations of OC, EC and also secondary organic carbon (SOC) in the spring and summer were lower than those in the autumn and winter. SOC had more percentages of increase than primary organic carbon (POC) during the winter. The sums of crustal elements (Al, Ca, Fe, Mg, Ti, Ba, and Sr) were higher in the spring and autumn owing to more days with blowing or floating dust. The concentrations of heavy metals were at higher levels in the BTH area by comparison with other studies. In Shijiazhuang and Chengde, the PM

  8. Influenza viral membrane fusion is sensitive to sterol concentration but surprisingly robust to sterol chemical identity

    Science.gov (United States)

    Zawada, Katarzyna E.; Wrona, Dominik; Rawle, Robert J.; Kasson, Peter M.

    2016-01-01

    Influenza virions are enriched in cholesterol relative to the plasma membrane from which they bud. Previous work has shown that fusion between influenza virus and synthetic liposomes is sensitive to the amount of cholesterol in either the virus or the target membrane. Here, we test the chemical properties of cholesterol required to promote influenza fusion by replacing cholesterol with other sterols and assaying viral fusion kinetics. We find that influenza fusion with liposomes is surprisingly robust to sterol chemical identity, showing no significant dependence on sterol identity in target membranes for any of the sterols tested. In the viral membrane, lanosterol slowed fusion somewhat, while polar sterols produced a more pronounced slowing and inhibition of fusion. No other sterols tested showed a significant perturbation in fusion rates, including ones previously shown to alter membrane bending moduli or phase behavior. Although fusion rates depend on viral cholesterol, they thus do not require cholesterol’s ability to support liquid-liquid phase coexistence. Using electron cryo-microscopy, we further find that sterol-dependent changes to hemagglutinin spatial patterning in the viral membrane do not require liquid-liquid phase coexistence. We therefore speculate that local sterol-hemagglutinin interactions in the viral envelope may control the rate-limiting step of fusion. PMID:27431907

  9. Chemical factors affecting the interpretation of blood cyanide concentrations in fire victims.

    Science.gov (United States)

    Moriya, Fumio; Hashimoto, Yoshiaki

    2003-03-01

    The purpose of this study was to examine the effects of methemoglobinemia caused by fire gases on blood cyanide concentrations in fire victims. Twenty-two fire victims with postmortem intervals of 8-48 h were involved. Blood cyanide concentrations at the time of death (C(0)) were estimated using the formula: C(0)=Ce(0.046 t) (C=blood cyanide concentration detected at autopsy, 0.046=first-order rate constant of cyanide disappearing from blood in corpses, and t=postmortem interval). Total (free and combined with cyanide) methemoglobin (MetHb) content was used to estimate the maximum capacity of MetHb for combining cyanide. Blood cyanide concentrations at the time of death were very high (5.32-6.47 mg/l) in five victims. Three showed high saturation (54.7-63.0%) of carboxyhemoglobin (CO-Hb) and elevated total MetHb contents (2.6-5.0%). MetHb at these levels is capable of scavenging up to 8.6-11.4 mg/l of blood cyanide. Thus, blood cyanide might have been completely combined with MetHb at the time of their death. In the remaining two victims, CO-Hb saturation was not high (30.9 and 37.9%) and no free MetHb was detected. As a result they may have exhibited severe toxic effects of cyanide at the time of their death. Our results indicate that MetHb contents and CO-Hb saturation should be determined to evaluate the toxic effects of cyanide in fire victims.

  10. Evaluation of Oxygen Concentrators and Chemical Oxygen Generators at Altitude and Temperature Extremes

    Science.gov (United States)

    2015-04-22

    producing similar results. Oxygen concentrators have also shown to be an effective and economical substitute for compressed oxygen cylinders in remote high... Fischer et al. [10] conducted a study in an altitude chamber with volunteers having chronic obstructive pulmonary disease using five commercially...interest in employing this technology in areas where providing oxygen in cylinders or in liquid form is logistically difficult or economically

  11. Effect of tri-sodium citrate concentration on structural, optical and electrical properties of chemically deposited tin sulfide films

    Energy Technology Data Exchange (ETDEWEB)

    Gode, F., E-mail: ftmgode@gmail.com [Department of Physics, Mehmet Akif Ersoy University, 15030 Burdur (Turkey); Guneri, E. [Department of Primary Education, Erciyes University, 38039 Kayseri (Turkey); Baglayan, O. [Department of Physics, Anadolu University, 26470 Eskisehir (Turkey)

    2014-11-01

    Graphical abstract: - Highlights: • SnS thin films grown by CBD in different concentration of tri-sodium citrate. • Grain size increases, while surface roughness decreases, with concentration. • Optical band gap decreases from 1.40 eV to 1.17 eV with increasing concentration. • Electrical conductivity improves with increasing concentration. - Abstract: Tin sulfide thin films were deposited onto glass substrates by chemical bath deposition. The effects of molar concentration of the complexing agent, tri-sodium citrate, on the structural, morphological, optical and electrical properties of the films were investigated. The films are characterized by X-ray diffraction, scanning electron microscopy, atomic force microscopy, optical absorption spectroscopy and Hall effect measurements. Polycrystalline film structure in orthorhombic phase was determined. Flower-like spherical grains are observed on the surface. While their average size increased from 345 nm to 750 nm when the tri-sodium citrate concentration was increased from 6.4 × 10{sup −3} M to 8.0 × 10{sup −3} M, the surface roughness varied in an opposite manner from approximately 120.18 nm to 29.36 nm. For these concentrations, optical band gap of the films decreased from 1.40 eV to 1.17 eV, whereas the Hall conductivity, mobility and carrier concentration of the films increased slightly from 5.91 × 10{sup −5} to 8.78 × 10{sup −5} (Ω cm){sup −1}, from 148 to 228 cm{sup 2} V{sup −1} s{sup −1} and from 1.73 × 10{sup 12} to 3.59 × 10{sup 12} cm{sup −1}, respectively.

  12. Biodegradation testing of chemicals with high Henry's constants - Separating mass and effective concentration reveals higher rate constants.

    Science.gov (United States)

    Birch, Heidi; Andersen, Henrik R; Comber, Mike; Mayer, Philipp

    2017-05-01

    During simulation-type biodegradation tests, volatile chemicals will continuously partition between water phase and headspace. This study addressed how (1) this partitioning affects test results and (2) can be accounted for by combining equilibrium partition and dynamic biodegradation models. An aqueous mixture of 9 (semi)volatile chemicals was first generated using passive dosing and then diluted with environmental surface water producing concentrations in the ng/L to μg/L range. After incubation for 2 h to 4 weeks, automated Headspace Solid Phase Microextraction (HS-SPME) was applied directly on the test systems to measure substrate depletion by biodegradation relatively to abiotic controls. HS-SPME was also applied to determine air to water partitioning ratios. Biodegradation rate constants relating to the chemical in the water phase, kwater, were generally a factor 1 to 11 times higher than biodegradation rate constants relating to the total mass of chemical in the test system, ksystem, with one exceptional factor of 72 times for a long chain alkane. True water phase degradation rate constants were found (i) more appropriate for risk assessment than test system rate constants, (ii) to facilitate extrapolation to other air-water systems and (iii) to be better defined input parameters for aquatic exposure and fate models.

  13. Organic and Nitrogen Fertilization of Soil under ‘Syrah’ Grapevine: Effects on Soil Chemical Properties and Nitrate Concentration

    Directory of Open Access Journals (Sweden)

    Davi José Silva

    2016-01-01

    Full Text Available ABSTRACT Viticulture is an activity of great social and economic importance in the lower-middle region of the São Francisco River valley in northeastern Brazil. In this region, the fertility of soils under vineyards is generally poor. To assess the effects of organic and nitrogen fertilization on chemical properties and nitrate concentrations in an Argissolo Vermelho-Amarelo (Typic Plinthustalf, a field experiment was carried out in Petrolina, Pernambuco, on Syrah grapevines. Treatments consisted of two rates of organic fertilizer (0 and 30 m3 ha-1 and five N rates (0, 10, 20, 40, and 80 kg ha-1, in a randomized block design arranged in split plots, with five replications. The organic fertilizer levels represented the main plots and the N levels, the subplots. The source of N was urea and the source of organic fertilizer was goat manure. Irrigation was applied through a drip system and N by fertigation. At the end of the third growing season, soil chemical properties were determined and nitrate concentration in the soil solution (extracted by porous cups was determined. Organic fertilization increased organic matter, pH, EC, P, K, Ca, Mg, Mn, sum of bases, base saturation, and CEC, but decreased exchangeable Cu concentration in the soil by complexation of Cu in the organic matter. Organic fertilization raised the nitrate concentration in the 0.20-0.40 m soil layer, making it leachable. Nitrate concentration in the soil increased as N rates increased, up to more than 300 mg kg-1 in soil and nearly 800 mg L-1 in the soil solution, becoming prone to leaching losses.

  14. Source apportionment of PM2.5 chemically speciated mass and particle number concentrations in New York City

    Science.gov (United States)

    Masiol, M.; Hopke, P. K.; Felton, H. D.; Frank, B. P.; Rattigan, O. V.; Wurth, M. J.; LaDuke, G. H.

    2017-01-01

    The major sources of fine particulate matter (PM2.5) in New York City (NYC) were apportioned by applying positive matrix factorization (PMF) to two different sets of particle characteristics: mass concentrations using chemical speciation data and particle number concentrations (PNC) using number size distribution, continuously monitored gases, and PM2.5 data. Post-processing was applied to the PMF results to: (i) match with meteorological data, (ii) use wind data to detect the likely locations of the local sources, and (iii) use concentration weighted trajectory models to assess the strength of potential regional/transboundary sources. Nine sources of PM2.5 mass were apportioned and identified as: secondary ammonium sulfate, secondary ammonium nitrate, road traffic exhaust, crustal dust, fresh sea-salt, aged sea-salt, biomass burning, residual oil/domestic heating and zinc. The sources of PNC were investigated using hourly average number concentrations in six size bins, gaseous air pollutants, mass concentrations of PM2.5, particulate sulfate, OC, and EC. These data were divided into 3 periods indicative of different seasonal conditions. Five sources were resolved for each period: secondary particles, road traffic, NYC background pollution (traffic and oil heating largely in Manhattan), nucleation and O3-rich aerosol. Although traffic does not account for large amounts of PM2.5 mass, it was the main source of particles advected from heavily trafficked zones. The use of residual oil had limited impacts on PM2.5 mass but dominates PNC in cold periods.

  15. Valence shell charge concentration (VSCC) evolution: a tool to investigate the transformations within a VSCC throughout a chemical reaction.

    Science.gov (United States)

    Cortés-Guzmán, Fernando; Gómez, Rosa María; Rocha-Rinza, Tomas; Sánchez-Obregón, María Azucena; Guevara-Vela, José Manuel

    2011-11-17

    Theoretical studies about reaction mechanisms are usually limited to the determination of the energetic paths that connect reactants, transition states, and products. Recently, our group proposed the structural evolution, which has provided insights about the molecular structure changes occurring along a reaction path. Structural evolution may be defined as the development of a chemical reaction system across the partitioning of the nuclear configuration space into a finite number of structural regions defined on account of the topology of a scalar field, e.g., the electron density. In this paper, we present a tool to investigate within the framework of the Quantum Theory of Atoms in Molecules the evolvement of the Valence Shell Charge Concentration, the VSCC evolution, which is the description of the changes of electron density concentrations and depletions around the bonding area of an atom. The VSCC evolution provides supplementary information to the structural evolution because it allows the analysis of valence shells within a structural region, i.e., a subset of R(Q) with the same connectivity among the atoms forming a molecule. This new approach constitutes also a complement to the Valence-Shell Electron Pair Repulsion (VSEPR) model because it gives an account of the adjustments of electron pairs in the valence shell of an atom across a chemical reaction. The insertion reaction in the hydroformylation reaction of ethylene, the reduction of cyclohexanone with lithium aluminum hydride, the oxidation of methanol with chlorochromate, and the bimolecular nucleophilic substitution of CH(3)F with F(-) are used as representatives examples of the application of the VSCC evolution. Overall, this paper shows how the VSCC evolution through an analysis of the modifications of local charge concentrations and depletions in individual steps of a chemical reaction gives new insights about these processes.

  16. Chemically-induced alteration of UDP-glucuronic acid concentration in rat liver.

    Science.gov (United States)

    Watkins, J B; Klaassen, C D

    1983-01-01

    Since many xenobiotics alter hepatic UDP-glucuronosyltransferase activity, their effect on UDPGA concentration was determined. Rats were pretreated with: 1) microsomal enzyme inducers (7,8-benzoflavone, benzo(a)pyrene, butylated hydroxyanisole, isosafrole, 3-methylcholanthrene, phenobarbital, pregnenolone-16 alpha-carbonitrile (PCN), 2,3,7,8-tetrachlorodibenzo-p-dioxin, trans-stilbene oxide); 2) inhibitors of microsomal enzymes (cobaltous chloride, piperonyl butoxide, SKF 525-A, borneol, galactosamine); 3) hepatotoxins (allyl alcohol, aflatoxin B1, alpha-naphthylisothiocyanate, bromobenzene, cadmium chloride, carbon tetrachloride, 1,1-dichloroethylene), and 4) commonly used anesthetics (pentobarbital, urethane, diethyl ether, halothane, enflurane, methoxyflurane). Rats were decapitated before removal of the liver. All inducers except PCN and isosafrole increased UDPGA 36-85% above control. Mixed-function oxidase inhibitors had no effect whereas borneol and galactosamine reduced UDPGA 85-90%. Aflatoxin B1 and cadmium produced decreases of 59 and 25%, respectively. Hepatic UDPGA content was diminished 70-95% after exposure to the inhalation anesthetics, whereas the other anesthetics reduced UDPGA about 25%. Thus, numerous xenobiotics alter the concentration of UDPGA in rat liver, which may influence the rate of glucoronidation.

  17. Physical and chemical changes in whey protein concentrate stored at elevated temperature and humidity.

    Science.gov (United States)

    Tunick, Michael H; Thomas-Gahring, Audrey; Van Hekken, Diane L; Iandola, Susan K; Singh, Mukti; Qi, Phoebe X; Ukuku, Dike O; Mukhopadhyay, Sudarsan; Onwulata, Charles I; Tomasula, Peggy M

    2016-03-01

    In a case study, we monitored the physical properties of 2 batches of whey protein concentrate (WPC) under adverse storage conditions to provide information on shelf life in hot, humid areas. Whey protein concentrates with 34.9 g of protein/100g (WPC34) and 76.8 g of protein/100g (WPC80) were stored for up to 18 mo under ambient conditions and at elevated temperature and relative humidity. The samples became yellower with storage; those stored at 35 °C were removed from the study by 12 mo because of their unsatisfactory appearance. Decreases in lysine and increases in water activity, volatile compound formation, and powder caking values were observed in many specimens. Levels of aerobic mesophilic bacteria, coliforms, yeast, and mold were <3.85 log10 cfu/g in all samples. Relative humidity was not a factor in most samples. When stored in sealed bags, these samples of WPC34 and WPC80 had a shelf life of 9 mo at 35 °C but at least 18 mo at lower temperatures, which should extend the market for these products.

  18. Chemical composition and properties of spray-dried sugar beet concentrate obtained after ultrafiltration of diffusion juice

    Directory of Open Access Journals (Sweden)

    Regiec Piotr

    2015-03-01

    Full Text Available Ultrafiltration of diffusion juice is a method that can reduce environmental pollution during the production of sugar. A by-product (concentrate of ultrafiltration contains a large amount of sucrose, but due to its properties, it is difficult to manage. The aim of this study was to determine the effects of the temperature used during drying of diffusion juice concentrates on the content of certain components and characteristics of resultant preparations. Diffusion juice obtained from one of the Polish sugar plants was subjected to ultrafiltration and the obtained concentrates were dried in a spray dryer. In the dried samples, the following parameters were analyzed: dry mass, sucrose, total ash, protein, crude fiber and color. It has been declared that the degree of concentration and drying temperature influenced the chemical composition and the properties of the dehydrated diffusion juice concentrates. An increase in drying temperature was accompanied by the increased content of dry mass, protein, ash and fiber content in the preparations. The greater the degree of juice concentration, the greater was the content of dry mass, ash, and fiber. Inversely, the greater the degree of juice concentration, the lower the content of sucrose. The brightest color of the dehydrated product was observed at the drying temperature of 200°C. Spray-drying may be used for waste management after the diffusion juice membrane filtration, and the resultant preparations might be used in the production of feedstuff or food industry in general e.g. as sucrose source, in fermentation processes or in microorganisms propagation.

  19. STUDY OF CHEMICAL INTERACTION OF MAGNESIA CEMENT WITH HIGH CONCENTRATION MAGNESIUM CHLORIDE SOLUTIONS

    Directory of Open Access Journals (Sweden)

    DEREVIANKO V. N.

    2015-10-01

    Full Text Available Problem statement. In activating MgO by electrolyte salts, as a result of formation of non water-resist magnesium silicate hydrate are obtained the durable cement stone having the low water-resist. I. P. Vyrodov considers [9; 5], that magnesia cement curing in mixing with sufficiently concentrated (C > 20 % solutions MgCl2 is caused with the crystallization of oxyhydrochloride composition: 3MgO∙MgCl2∙11Н2О, 5MgO∙MgCl2∙13Н2О and 7MgO∙MgCl2∙15Н2О. In the lower concentration parts of MgCl2 solution is formed a transitional compound of Mg[(OHnCl2-n] with isomorphous Mg(OH2 structure. At very low Cl concentration only Mg(OH2 is practically formed. Purpose. The Formation of water-resist magnesium silicate hydrates for obtaining of fast curing and solid structure of the magnesia stone. Conclusion. The dependence of the formation of the magnesia stone from the ratio (MgO/MgCl2 of the magnesia cement (MgO and the magnesium chloride solution (MgCl2 of different density has been identified in order to obtain the best content for oxyhydrochloride 3MgO•MgCl2•11Н2О, 5MgO•MgCl2•13Н2О and magnesium hydroxide (Mg(OH2. In putting into the system MgO∙–∙H2О of the silicic acid or fine ground quartz grains with size of less than 20 – 30 microns, over 1 month for the magnesium silicate hydrates formation is needed, where from 2 to 5 % of the total number of newgrowths are created. The study is proved by the expert opinion, that magnesium silicate hydrates do not have binding properties, unlike calcium silicate hydrates, and the main role in the system curing is played with the Mg(OH2 gel recrystallization, which provides the acceptable stone strength (R ≈ 30MPa in a few years. It has been also established, that in mixing of cement with low concentration MgO solutions of less than 1,5 mol/l (or 13% 1,1g/sm3, the final product in the stone structure is Mg(OH2. With increasing the sealer (MgCl2 solution there is formed by turn in

  20. Production Mechanism, Number Concentration, Size Distribution, Chemical Composition, and Optical Properties of Sea Spray Aerosols Workshop, Summer 2012

    Energy Technology Data Exchange (ETDEWEB)

    Meskhidze, Nicholas [NCSU

    2013-10-21

    The objective of this workshop was to address the most urgent open science questions for improved quantification of sea spray aerosol-radiation-climate interactions. Sea spray emission and its influence on global climate remains one of the most uncertain components of the aerosol-radiation-climate problem, but has received less attention than other aerosol processes (e.g. production of terrestrial secondary organic aerosols). Thus, the special emphasis was placed on the production flux of sea spray aerosol particles, their number concentration and chemical composition and properties.

  1. Predicting dissolved oxygen concentration using kernel regression modeling approaches with nonlinear hydro-chemical data.

    Science.gov (United States)

    Singh, Kunwar P; Gupta, Shikha; Rai, Premanjali

    2014-05-01

    Kernel function-based regression models were constructed and applied to a nonlinear hydro-chemical dataset pertaining to surface water for predicting the dissolved oxygen levels. Initial features were selected using nonlinear approach. Nonlinearity in the data was tested using BDS statistics, which revealed the data with nonlinear structure. Kernel ridge regression, kernel principal component regression, kernel partial least squares regression, and support vector regression models were developed using the Gaussian kernel function and their generalization and predictive abilities were compared in terms of several statistical parameters. Model parameters were optimized using the cross-validation procedure. The proposed kernel regression methods successfully captured the nonlinear features of the original data by transforming it to a high dimensional feature space using the kernel function. Performance of all the kernel-based modeling methods used here were comparable both in terms of predictive and generalization abilities. Values of the performance criteria parameters suggested for the adequacy of the constructed models to fit the nonlinear data and their good predictive capabilities.

  2. Methods of soil resampling to monitor changes in the chemical concentrations of forest soils

    Science.gov (United States)

    Lawrence, Gregory B.; Fernandez, Ivan J.; Hazlett, Paul W.; Bailey, Scott W.; Ross, Donald S.; Villars, Thomas R.; Quintana, Angelica; Ouimet, Rock; McHale, Michael; Johnson, Chris E.; Briggs, Russell D.; Colter, Robert A.; Siemion, Jason; Bartlett, Olivia L.; Vargas, Olga; Antidormi, Michael; Koppers, Mary Margaret

    2016-01-01

    Recent soils research has shown that important chemical soil characteristics can change in less than a decade, often the result of broad environmental changes. Repeated sampling to monitor these changes in forest soils is a relatively new practice that is not well documented in the literature and has only recently been broadly embraced by the scientific community. The objective of this protocol is therefore to synthesize the latest information on methods of soil resampling in a format that can be used to design and implement a soil monitoring program. Successful monitoring of forest soils requires that a study unit be defined within an area of forested land that can be characterized with replicate sampling locations. A resampling interval of 5 years is recommended, but if monitoring is done to evaluate a specific environmental driver, the rate of change expected in that driver should be taken into consideration. Here, we show that the sampling of the profile can be done by horizon where boundaries can be clearly identified and horizons are sufficiently thick to remove soil without contamination from horizons above or below. Otherwise, sampling can be done by depth interval. Archiving of sample for future reanalysis is a key step in avoiding analytical bias and providing the opportunity for additional analyses as new questions arise.

  3. Variations of biomarkers response in mussels Mytilus galloprovincialis to low, moderate and high concentrations of organic chemicals and metals.

    Science.gov (United States)

    Perić, Lorena; Nerlović, Vedrana; Žurga, Paula; Žilić, Luka; Ramšak, Andreja

    2017-05-01

    The changes of acetylcholinesterase activity (AChE), metallothioneins content (MTs), catalase activity (CAT) and lipid peroxidation (LPO) were assessed after 4 days exposure of mussels Mytilus galloprovincialis to a wide range of sublethal concentrations of chlorpyrifos (CHP, 0.03-100 μg/L), benzo(a)pyrene (B(a)P, 0.01-100 μg/L), cadmium (Cd, 0.2-200 μg/L) and copper (Cu, 0.2-100 μg/L). The activity of AChE in the gills decreased after exposure to CHP and Cu, whereas no change of activity was detected after exposure to B(a)P and Cd. Both induction and decrease of MTs content in digestive gland occurred after exposure to CHP and B(a)P, while a marked increase was evident at highest exposure concentrations of Cd. The content of MTs progressively decreased of MTs with increasing concentration of Cu. CAT activity and LPO in the gills did not change after exposure to any of the chemicals. The results demonstrate different response profile in relation to the type of chemical compound, and highlight the potential implications for evaluation of biological effect of contaminants in marine environment. Furthermore, the AChE activity in the gills and MTs content in the digestive gland could be modulated by CHP and Cu at environmentally relevant concentrations indicating the potential risks of short-term transient mussels exposure that may occur due to run-off from land or accidental releases.

  4. Effect of tri-sodium citrate concentration on structural, optical and electrical properties of chemically deposited tin sulfide films

    Science.gov (United States)

    Gode, F.; Guneri, E.; Baglayan, O.

    2014-11-01

    Tin sulfide thin films were deposited onto glass substrates by chemical bath deposition. The effects of molar concentration of the complexing agent, tri-sodium citrate, on the structural, morphological, optical and electrical properties of the films were investigated. The films are characterized by X-ray diffraction, scanning electron microscopy, atomic force microscopy, optical absorption spectroscopy and Hall effect measurements. Polycrystalline film structure in orthorhombic phase was determined. Flower-like spherical grains are observed on the surface. While their average size increased from 345 nm to 750 nm when the tri-sodium citrate concentration was increased from 6.4 × 10-3 M to 8.0 × 10-3 M, the surface roughness varied in an opposite manner from approximately 120.18 nm to 29.36 nm. For these concentrations, optical band gap of the films decreased from 1.40 eV to 1.17 eV, whereas the Hall conductivity, mobility and carrier concentration of the films increased slightly from 5.91 × 10-5 to 8.78 × 10-5 (Ω cm)-1, from 148 to 228 cm2 V-1 s-1 and from 1.73 × 1012 to 3.59 × 1012 cm-1, respectively.

  5. Estimation of time-variable fast flow path chemical concentrations for application in tracer-based hydrograph separation analyses

    Science.gov (United States)

    Kronholm, Scott C.; Capel, Paul D.

    2016-09-01

    Mixing models are a commonly used method for hydrograph separation, but can be hindered by the subjective choice of the end-member tracer concentrations. This work tests a new variant of mixing model that uses high-frequency measures of two tracers and streamflow to separate total streamflow into water from slowflow and fastflow sources. The ratio between the concentrations of the two tracers is used to create a time-variable estimate of the concentration of each tracer in the fastflow end-member. Multiple synthetic data sets, and data from two hydrologically diverse streams, are used to test the performance and limitations of the new model (two-tracer ratio-based mixing model: TRaMM). When applied to the synthetic streams under many different scenarios, the TRaMM produces results that were reasonable approximations of the actual values of fastflow discharge (±0.1% of maximum fastflow) and fastflow tracer concentrations (±9.5% and ±16% of maximum fastflow nitrate concentration and specific conductance, respectively). With real stream data, the TRaMM produces high-frequency estimates of slowflow and fastflow discharge that align with expectations for each stream based on their respective hydrologic settings. The use of two tracers with the TRaMM provides an innovative and objective approach for estimating high-frequency fastflow concentrations and contributions of fastflow water to the stream. This provides useful information for tracking chemical movement to streams and allows for better selection and implementation of water quality management strategies.

  6. Development of Quantum Chemical Method to Calculate Half Maximal Inhibitory Concentration (IC50 ).

    Science.gov (United States)

    Bag, Arijit; Ghorai, Pradip Kr

    2016-05-01

    Till date theoretical calculation of the half maximal inhibitory concentration (IC50 ) of a compound is based on different Quantitative Structure Activity Relationship (QSAR) models which are empirical methods. By using the Cheng-Prusoff equation it may be possible to compute IC50 , but this will be computationally very expensive as it requires explicit calculation of binding free energy of an inhibitor with respective protein or enzyme. In this article, for the first time we report an ab initio method to compute IC50 of a compound based only on the inhibitor itself where the effect of the protein is reflected through a proportionality constant. By using basic enzyme inhibition kinetics and thermodynamic relations, we derive an expression of IC50 in terms of hydrophobicity, electric dipole moment (μ) and reactivity descriptor (ω) of an inhibitor. We implement this theory to compute IC50 of 15 HIV-1 capsid inhibitors and compared them with experimental results and available other QASR based empirical results. Calculated values using our method are in very good agreement with the experimental values compared to the values calculated using other methods.

  7. Worldwide estimation of river concentrations of any chemical originating from sewage-treatment plants using dilution factors.

    Science.gov (United States)

    Keller, Virginie D J; Williams, Richard J; Lofthouse, Caryn; Johnson, Andrew C

    2014-02-01

    Dilution factors are a critical component in estimating concentrations of so-called "down-the-drain" chemicals (e.g., pharmaceuticals) in rivers. The present study estimated the temporal and spatial variability of dilution factors around the world using geographically referenced data sets at 0.5° × 0.5° resolution. Domestic wastewater effluents were derived from national per capita domestic water use estimates and gridded population. Monthly and annual river flows were estimated by accumulating runoff estimates using topographically derived flow directions. National statistics, including the median and interquartile range, were generated to quantify dilution factors. Spatial variability of the dilution factor was found to be considerable; for example, there are 4 orders of magnitude in annual median dilution factor between Canada and Morocco. Temporal variability within a country can also be substantial; in India, there are up to 9 orders of magnitude between median monthly dilution factors. These national statistics provide a global picture of the temporal and spatial variability of dilution factors and, hence, of the potential exposure to down-the-drain chemicals. The present methodology has potential for a wide international community (including decision makers and pharmaceutical companies) to assess relative exposure to down-the-drain chemicals released by human pollution in rivers and, thus, target areas of potentially high risk.

  8. A system for vertical profile measurements of sensible heat and chemical concentrations near the ground surface

    Energy Technology Data Exchange (ETDEWEB)

    Hyppoenen, M.; Walden, J.A.

    1996-12-31

    The design, construction and measurements of a computer controlled system applicable to flux measurements of a scalar quantity by the gradient technique are described. Accuracy requirements for the measured variables which are used for flux calculations are considered, together with some practical aspects concerning data storage and control. The construction includes the hardware and the data acquisition, sample intake, and temperature measurement systems. The measurements comprise laboratory tests of the temperature probes and the hardware as well as field tests over wheat and grass land for temperature and wind speed and ozone (O{sub 3}), carbon dioxide (CO{sub 2}) and nitrous oxide (N{sub 2}O) concentration profiles. The hardware takes care of most of the operation and only the necessary part is done by the software. The data acquisition system is flexible, accepting the input of either digital and/or analog signals. It also controls the whole system, storing all the data in a single data file. The sample intake unit is designed to take continuous samples in to the monitors as well as grab samples into the canisters. Samples can be selected from one to four levels with no dead volumes in the sampling tubes. The temperature measurement system is constructed using a pair of temperature probes, Pt-100, which are connected to the same signal processing card, in order to remove the offset of the electronic components as well as the bias associated with single probes. This ensures the accuracy of the probes down to 0.005 deg C. According to the field measurements, the relative error limits for the sensible heat fluxes varied from 7 to 20 % in an unstable atmospheric situation. For the ozone flux, the error limits varied from 20 to 100 %, indicating a much poorer accuracy of the monitor compared to the temperature probes. (orig.) 16 refs.

  9. Concentrations and chemical compositions of fine particles (PM2.5) during haze and non-haze days in Beijing

    Science.gov (United States)

    Zhang, Yang; Huang, Wei; Cai, Tianqi; Fang, Dongqing; Wang, Yuqin; Song, Jian; Hu, Min; Zhang, Yuanxun

    2016-06-01

    To investigate the chemical properties of PM2.5 and put forward reasonable control measures, daily samples of PM2.5 were collected at an urban site in Beijing from August 4 to September 3 of 2012 using two 2-channel samplers. Chemical analysis was conducted for eight water soluble inorganic ions (WSII, including Na+, NH4+, K+, Mg2 +, Ca2 +, Cl-, NO3-, and SO42 -), organic carbon (OC) and elementary carbon (EC). PM2.5 concentrations ranged from 8.8 to 218.6 μg m- 3, with an average concentration of 80.6 ± 57.3 μg m- 3. WSII, the most dominant PM2.5 constituents contributing 60 ± 18% of its mass, ranged from 3.1 to 172.2 μg m- 3. SO42 -, NO3-, and NH4+ dominated WSII (90 ± 28%) and their concentrations were 1.3-105.7 μg m- 3, 0.5-52.7 μg m- 3 and 0.3-33.5 μg m- 3, respectively. The concentrations of OC and EC were 3.0-28.8 μgC m- 3 and 0.8-7.4 μgC m- 3, constituting 17.6% and 4.9% of PM2.5, respectively. Three serious pollution episodes (haze days) occurred during the campaign. PM2.5 and its chemical species showed substantial increases during haze episodes. The greater enhancement factors for SO42 - (4.5), NO3- (4.0), and NH4+ (4.2) during haze days compared to non-haze days were obtained, suggesting that these secondary inorganic ions play important roles in the formation of haze. The average ratio of NO3-/SO42 - was 0.52. Ion balance calculations showed that PM2.5 samples were acidic during haze periods and close to neutral during non-haze days. Correlation analysis between the major ions was conducted and the results suggested that the main forms of NH4+ might be (NH4)2SO4. In addition, the variations between haze days and non-haze days for OC, EC, and the ratio of OC/EC were discussed.

  10. Role of primary substrate composition and concentration on attenuation of trace organic chemicals in managed aquifer recharge systems

    KAUST Repository

    Alidina, Mazahirali

    2014-11-01

    This study was undertaken to investigate the role of primary substrate composition and concentration on the attenuation of biodegradable emerging trace organic chemicals (TOrCs) in simulated managed aquifer recharge (MAR) systems. Four sets of soil columns were established in the laboratory, each receiving synthetic feed solutions comprising different ratios and concentrations of peptone-yeast and humic acid as the primary substrate to investigate the effect on removal of six TOrCs (atenolol, caffeine, diclofenac, gemfibrozil, primidone, and trimethoprim). Based on abiotic control experiments, adsorption was not identified as a significant attenuation mechanism for primidone, gemfibrozil and diclofenac. Caffeine, atenolol and trimethoprim displayed initial adsorptive losses, however, adsorption coefficients derived from batch tests confirmed that adsorption was limited and in the long-term experiment, biodegradation was the dominant attenuation process. Within a travel time of 16h, caffeine - an easily degradable compound exhibited removal exceeding 75% regardless of composition or concentration of the primary substrate. Primidone - a poorly degradable compound, showed no removal in any column regardless of the nature of the primary substrate. The composition and concentration of the primary substrate, however, had an effect on attenuation of moderately degradable TOrCs, such as atenolol, gemfibrozil and diclofenac, with the primary substrate composition seeming to have a larger impact on TOrC attenuation than its concentration. When the primary substrate consisted mainly of refractory substrate (humic acid), higher removal of the moderately degradable TOrCs was observed. The microbial communities in the columns receiving more refractory carbon, were noted to be more diverse and hence likely able to express a wider range of enzymes, which were more suitable for TOrC transformation. The effect of the primary substrate on microbial community composition, diversity

  11. Effects of Buffer Salt Concentration on the Dominated Deposition Mechanism and Optical Characteristics of Chemically Deposited Cadmium Sulfide Thin Films

    Science.gov (United States)

    Kakhaki, Z. Makhdoumi; Youzbashi, A.; Sangpour, P.; Kazemzadeh, A.; Naderi, N.; Bazargan, A. M.

    2016-02-01

    Effects of buffer salt concentration on the rate of deposition, dominated deposition mechanism and subsequently the structural, morphological, and optical properties of cadmium sulfide (CdS) thin films deposited by chemical bath deposition (CBD) on glass substrate were investigated. The precursors were chosen to be cadmium chloride (CdCl2) as the cadmium source, thiourea (CS(NH2)2) as the sulfur source, ammonium nitrate (NH4NO3) as the buffer salt and ammonia as the complexing agent and the pH controller. The influence of the NH4NO3 concentration on the structure, morphology, film uniformity, stoichiometry and optical properties of CdS thin films was also studied by X-ray diffractometer (XRD), field emission scanning electron microscope (FE-SEM), energy dispersive X-ray (EDX) spectroscope, uv-visible and photoluminescence (PL) spectroscopes. The XRD studies revealed that all the deposited films exhibited a (002)h/(111)c preferred orientation. The crystallite size was increased from 20nm to 30nm by the increase of concentration of NH4NO3 from 0.5M to 2.5M. The morphology of CdS thin films were agglomerated spherical particles consisted of smaller particles. The surface of thin films deposited at the NH4NO3 concentration of 0.5M was compact and smooth. The increase of the concentration of NH4NO3 decreased the packing density of the films. The optical band gap was in the range of 2.25-2.4eV, which was decreased by the decrement of packing density. The PL spectra showed two peaks centered at 400nm and 500nm which are attributed to violet and band-to-band emissions, respectively.

  12. Characterization of chemical composition and concentration of fine particulate matter during a transit strike in Ottawa, Canada

    Science.gov (United States)

    Ding, Luyi; Chan, Tak Wai; Ke, Fu; Wang, Daniel K. W.

    2014-06-01

    From December 10, 2008 to February 9, 2009, a strike stopped the public transit services in Ottawa, Ontario, Canada. To understand the changes in air quality associated with the transit strike, the chemical composition and concentration of the fine particulate matter with diameters less than 2.5 microns (PM2.5), collected before, during, and after the transit strike period, were evaluated. The collected PM2.5 samples were analyzed to determine the particulate matter mass, the levels of organic carbon (OC) and elemental carbon (EC), as well as the particulate non-polar semi-volatiles, e.g., polycyclic aromatic hydrocarbons (PAHs), hopanes, and steranes. Particle number size distributions measured during and after the transit strike period were also compared. Results indicated that during transit strike months, particle number size distributions were entirely dominated by nucleation mode particles leading to an increase in total particle number concentration by about 79%. In addition, particulate matter, organic carbon, and elemental carbon mass concentrations also increased by over 100%. The average total PAH levels during the strike months were higher by a factor of about 7. Elevated concentrations of high molecular weight PAHs (i.e., PAH with 5 and 6 rings) observed during the strike months suggested that there were more gasoline-powered vehicles on the roads over that period. The level of carcinogenic benzo[a]pyrene was higher by a factor of 5. Mass concentrations of hopanes and steranes were 30-98% higher during the strike months than non-strike months and exhibited strong correlations with EC suggesting the primary origin of these compounds. These results indicated that the increased traffic volume due to the passenger vehicles and the change in driving pattern during the transit strike period reduced the local air quality.

  13. Characteristics of concentrations and chemical compositions for PM2.5 in the region of Beijing, Tianjin, and Hebei, China

    Directory of Open Access Journals (Sweden)

    P. S. Zhao

    2013-05-01

    Full Text Available In order to study the temporal and spatial variations of PM2.5 and its chemical compositions in the region of Beijing, Tianjin, and Hebei (BTH, PM2.5 samples were collected at four urban sites in Beijing (BJ, Tianjin (TJ, Shijiazhuang (SJZ, and Chengde (CD, and also one site at Shangdianzi (SDZ regional background station over four seasons from 2009 to 2010. The samples were weighted for mass concentrations and analyzed in the laboratory for chemical profiles of 19 elements (Al, As, Ba, Ca, Cd, Co, Cr, Cu, Fe, K, Mg, Mn, Ni, P, Pb, Sr, Ti, V, and Zn, eight water-soluble inorganic ions (Na+, NH4+, K+, Mg2+, Ca2+, Cl−, NO3−, and SO42−, and carbon fractions (OC and EC. The concentrations of PM2.5 and its major chemical species were season dependent and showed spatially similar characteristics in the plain area of BTH. The average annual concentrations of PM2.5 were 71.8–191.2 μg m−3 at the five sites, with more than 90% of sampling days exceeding 50 μg m−3 at BJ, TJ, and SJZ. PM2.5 pollution was most serious at SJZ, and the annual concentrations of PM2.5, secondary inorganic ions, OC, EC, and most crustal elements were all highest. Due to stronger photochemical oxidation, the sum of concentrations of secondary inorganic ions (NH4+, NO3−, and SO42− was highest in the summer at SDZ, BJ, TJ, and CD. Analysis of electric charges of water-soluble inorganic ions indicated the existence of nitric acid or hydrochloric acid in PM2.5. For all five sites, the concentrations of OC, EC and also secondary organic carbon (SOC in the spring and summer were lower than those in the autumn and winter. SOC had more percentages of increase than primary organic carbon (POC during the winter. The sums of crustal elements (Al, Ca, Fe, Mg, Ti, Ba, and Sr were higher in the spring and autumn owing to more days with blowing or floating dust. The concentrations of heavy metals were at higher levels in the BTH area by comparison with other studies. In

  14. Variations of the aerosol concentration and chemical composition over the arid steppe zone of Southern Russia in summer

    Science.gov (United States)

    Artamonova, M. S.; Gubanova, D. P.; Iordanskii, M. A.; Lebedev, V. A.; Maksimenkov, L. O.; Minashkin, V. M.; Obvintsev, Y. I.; Chketiani, O. G.

    2016-12-01

    Variations in the surface aerosol over the arid steppe zone of Southern Russia have been measured. The parameters of atmospheric aerosol (mass concentration, both dispersed and elemental compositions) and meteorological parameters were measured in Tsimlaynsk raion (Rostov oblast). The chemical composition of aerosol particles in the atmospheric surface layer has been determined, and the coefficients of enrichment of elements with respect to clarkes in the Earth's crust have been calculated. It is shown that, in summer, arid aerosols are transported from both alkaline and sandy soils of Kalmykia to the air basin over the observation zone. Aerosol particles in the surface air layer over this region have been found to contain the products of combustion of oil, coal, and ethylized fuel. These combustion products make a small contribution to the total mass concentration of atmospheric aerosol; however, they are most hazardous to the health of people because of their sizes and heavy-metal contents. A high concentration of submicron sulfur-containing aerosol particles of chemocondensation nature has been recorded. Sources of aerosol of both natural and anthropogenic origins in southern Russia are discussed.

  15. Temperature varying photoconductivity of GeSn alloys grown by chemical vapor deposition with Sn concentrations from 4% to 11%

    Science.gov (United States)

    Hart, John; Adam, Thomas; Kim, Yihwan; Huang, Yi-Chiau; Reznicek, Alexander; Hazbun, Ramsey; Gupta, Jay; Kolodzey, James

    2016-03-01

    Pseudomorphic GeSn layers with Sn atomic percentages between 4.5% and 11.3% were grown by chemical vapor deposition using digermane and SnCl4 precursors on Ge virtual substrates grown on Si. The layers were characterized by x-ray diffraction rocking curves and reciprocal space maps. Photoconductive devices were fabricated, and the dark current was found to increase with Sn concentration. The responsivity of the photoconductors was measured at a wavelength of 1.55 μm using calibrated laser illumination at room temperature and a maximum value of 2.7 mA/W was measured for a 4.5% Sn device. Moreover, the responsivity for higher Sn concentration was found to increase with decreasing temperature. Spectral photoconductivity was measured using Fourier transform infrared spectroscopy. The photoconductive absorption edge continually increased in wavelength with increasing tin percentage, out to approximately 2.4 μm for an 11.3% Sn device. The direct band gap was extracted using Tauc plots and was fit to a bandgap model accounting for layer strain and Sn concentration. This direct bandgap was attributed to absorption from the heavy-hole band to the conduction band. Higher energy absorption was also observed, which was thought to be likely from absorption in the light-hole band. The band gaps for these alloys were plotted as a function of temperature. These experiments show the promise of GeSn alloys for CMOS compatible short wave infrared detectors.

  16. Whey protein concentrate and gum tragacanth as fat replacers in nonfat yogurt: chemical, physical, and microstructural properties.

    Science.gov (United States)

    Aziznia, S; Khosrowshahi, A; Madadlou, A; Rahimi, J

    2008-07-01

    The effect of whey protein concentrate (WPC) and gum tragacanth (GT) as fat replacers on the chemical, physical, and microstructural properties of nonfat yogurt was investigated. The WPC (7.5, 15, and 20 g/L) and GT (0.25, 0.5, 0.75, and 1 g/L) were incorporated into the skim milk slowly at 40 to 45 degrees C with agitation. The yogurt mixes were pasteurized at 90 degrees C for 10 min, inoculated with 0.1% starter culture, and incubated at 42 degrees C to pH 4.6, then refrigerated overnight at 5 degrees C. A control nonfat yogurt and control full fat yogurt were prepared as described, but without addition of WPC and GT. Increasing amount of WPC led to the increase in total solids, total protein, acidity, and ash content, whereas GT did not affect chemical parameters. Increasing WPC caused a more compact structure consisting of robust casein particles and large aggregates. Firmness was increased and susceptibility to syneresis was decreased as WPC increased. No significant difference was observed for firmness and syneresis of yogurt fortified with GT up to 0.5 g/L compared with control nonfat yogurt. Increasing the amount of gum above 0.5 g/L produced softer gels with a greater tendency for syneresis than the ones prepared without it. Addition of GT led to the coarser and more open structure compared with control yogurt.

  17. Assessment of physico-chemical qualities and heavy metal concentrations of Umgeni and Umdloti Rivers in Durban, South Africa.

    Science.gov (United States)

    Olaniran, Ademola O; Naicker, Kovashnee; Pillay, Balakrishna

    2014-04-01

    We assessed the effects of seasonal dynamics on the physico-chemical qualities and heavy metals concentrations of the Umgeni and Umdloti Rivers in Durban, South Africa. Water samples were taken from nine different sampling points and analysed for the following parameters; temperature, pH, turbidity, electrical conductivity (EC), biological oxygen demand (BOD5), chemical oxygen demand (COD), phosphate (PO4(2-)), nitrate (NO3(2-)), ammonium (NH4(+)), sulphate (SO4(2-)), lead (Pb(2+)), mercury (Hg(2+)), cadmium (Cd(2+)), aluminium (Al(3+)), and copper (Cu(2+)) using standard methods. The data showed variations it terms of the seasonal fluctuations and sampling regime as follows: temperature 12-26.5 °C; pH 5.96-8.45; turbidity 0.53-18.8 NTU; EC 15.8-5180 mS m(-1); BOD5 0.60-7.32 mg L(-1); COD 10.5-72.9 mg L(-1); PO4 (2-) South African Guidelines and World Health Organization tolerance limits for freshwater quality. We conclude that these water bodies are potentially hazardous to public health and this highlights the need for implementation of improved management strategies of these river catchments for continued sustainability.

  18. CHEMICALS

    CERN Multimedia

    Medical Service

    2002-01-01

    It is reminded that all persons who use chemicals must inform CERN's Chemistry Service (TIS-GS-GC) and the CERN Medical Service (TIS-ME). Information concerning their toxicity or other hazards as well as the necessary individual and collective protection measures will be provided by these two services. Users must be in possession of a material safety data sheet (MSDS) for each chemical used. These can be obtained by one of several means : the manufacturer of the chemical (legally obliged to supply an MSDS for each chemical delivered) ; CERN's Chemistry Service of the General Safety Group of TIS ; for chemicals and gases available in the CERN Stores the MSDS has been made available via EDH either in pdf format or else via a link to the supplier's web site. Training courses in chemical safety are available for registration via HR-TD. CERN Medical Service : TIS-ME :73186 or service.medical@cern.ch Chemistry Service : TIS-GS-GC : 78546

  19. Concentrations and chemical forms of potentially toxic metals in road-deposited sediments from different zones of Hangzhou, China

    Institute of Scientific and Technical Information of China (English)

    ZHANG Mingkui; WANG Hao

    2009-01-01

    The 25 road-deposited sediments were collected from five different land-use zones (industrial, residential, commercial, park, and countryside) in Hangzhou, China. The concentrations of metals (Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, and Zn) in these samples were determined using the ICP-AES after digestion with the mixture of HNO3-HF-HCl (aqua regia), and chemically fractionated using the modified BCR (the European Community Bureau of Reference) sequential extraction procedure. The highest metal concentration level was detected in the sample from industrial zone and commercial zone having heavy traffic. While the lowest metal level was noted in the street dust sample from residential zone, park, and countryside zone. The mobility sequence based on the sum of the BCR sequential extraction stages was: Zn (80.28%), Pb (78.68%), Cd (77.66%) > Cu (73.34%) > Mn (67.92%) > Co (41.66%) > Ni (30.36%) > Cr (21.56%), Fe (20.86%). Correlation analysis and principal component analysis were applied to the data matrix to evaluate the analytical results and to identify the possible pollution sources of metals. Factor analysis showed that these areas were mainly contaminated by three sources, namely lithology, traffic, and industry.

  20. An assessment of the concentrations of particulate polycyclic aromatic hydrocarbons (PAHs) in the aftermath of a chemical store fire incident

    Institute of Scientific and Technical Information of China (English)

    M. Radzi Bin Abas; Nasr Yousef M. J. Omar; M. Jamil Maah

    2004-01-01

    PM10 airborne particles and soot deposit collected after a fire incident at a chemical store were analyzed in order to determine the concentrations of polycyclic aromatic hydrocarbons(PAHs). The samples were extracted with 1:1 hexane-dichloromethane by ultrasonic agitation. The extracts were then subjected to gas chromatography-mass spectrometric(GC-MS) analysis. The total PAHs concentrations in airborne particles and soot deposit were found to be 3.27 ( 1.55 ng/m3 and 12.81 ( 24.37 μg/g, respectively. Based on the molecular distributions of PAHs and the interpretation of their diagnostic ratios such as PHEN/(PHEN + ANTH), FLT/(FLT + PYR) and BeP/(BeP + BaP), PAHs in both airborne particles and soot deposit may be inferred to be from the same source. The difference in the value of IP/(IP + BgP) for these samples indicated that benzo[g,h,i]perylene and coronene tend to be attached to finer particles and reside in the air for longer periods. Comparison between the molecular distributions of PAHs and their diagnostic ratios observed in the current study with those reported for urban atmospheric and roadside soil particles revealed that they are of different sources.

  1. Spectrofluorometric determination and chemical speciation of trace concentrations of tungsten species in water using the ion pairing reagent procaine hydrochloride.

    Science.gov (United States)

    El-Shahawi, M S; Al Khateeb, L A

    2012-01-15

    A highly selective and low cost extractive spectrofluorimetric method was developed for determination of trace concentrations of tungsten (VI) in water. The method was based upon solvent extraction of the developed ion associate [(PQH(+))(2)·WO(4)(2-)] of the fluorescent ion-pairing reagent [2-(diethylamino)ethyl 4 aminobenzoate] hydrochloride namely procaine hydrochloride, PQH(+)·Cl(-) and tungstate (WO(4)(2-)) in aqueous solution of pH 6-7 followed by measuring the resulting fluorescence enhancement in n-hexane at λ(ex/em)=270/320nm. The fluorescence intensity of PQH(+)·Cl(-) increased linearly on increasing tungstate concentration in the range 25-250μgL(-1). The limits of detection (LOD) and quantification (LOQ) of tungsten (VI) were found 7.51 and 24.75μgL(-1), respectively. Chemical composition of the developed ion associate and the molar absorptivity at 270nm were found to be [(PQH(+))(2)·WO(4)(2-)] and 2.7×10(4)Lmol(-1)cm(-1), respectively. Other oxidation states (III, IV, V) of tungsten species could also be determined after oxidation with H(2)O(2) in aqueous solution to tungsten (VI). The method was applied for analysis of tungsten in certified reference material (IAEA Soil-7) and wastewater samples. The results were compared successfully (>95%) with the data of inductively coupled plasma-mass spectrometry (ICP-MS).

  2. Estimation of Secondary Compounds Concentrations Contributed by Biogenic VOC With Chemical Transport Model in the Central Area of Japan

    Science.gov (United States)

    Yamamoto, K.; Kanemaru, A.; Okumura, M.; Tohno, S.

    2008-12-01

    Biogenic VOC (BVOC) has comparably large contribution to generation of secondary air pollutants, such as photochemical oxidant or urban aerosol. In this study a BVOC emission inventory in the Kansai area, which is located in the central part of Japan, based on the field observation was developed. Some validations of the inventory were conducted by estimating the concentration distribution of oxidants with this developed and an existing BVOC emission inventory in Kansai area by meteorological model MM5 and atmospheric chemical transport model CMAQ. In the development of BVOC emission, the vegetation map by the Biodiversity Center of Japan which had been arranged as basic information on natural environmental preservation in a regional standard mesh (the third mesh) in 1999 was used. In this study isoprene and the mono-terpene were taken up as BVOC. Quercus crispula and Quercus serrata were selected as the source of isoprene, and Cryptomeria japonica, Chamaecyparis obtuse, Quercus phillyraeoides, Pinus densiflora, and Pinus thunbergii were selected as sources of mono-terpene. The parameter of the basic emission rate included in the model was decided by arranging the result of the observation in Kansai Research Center of Forestry and Forest Products Research Institute in each season. This emission flux from each species were calculated by G93 model by Guenther et al. and meteorological fields for the model, such as temperatures and sunlight intensities, were renewed hour by hour, therefore, this emission inventory has a high time resolution according to the season and time. In calculating meteorological fields, meteorological model MM5 Ver.3.7 was conducted in Japanese standard mesh in the selected five days of April, July, and October in 2004, and January 2005 respectively, and taking out the result of wind velocities and temperatures for substituting to the G93 model. Then atmospheric chemical transport model CMAQ Ver.4.6 with the emission inventories and

  3. Evolution of trace gas concentrations and the chemical properties of particles at the top of the Mexico City boundary layer.

    Science.gov (United States)

    Ochoa, C.; Baumgardner, D.; Grutter, M.

    2007-05-01

    The Altzomoni ridge is located in the Cortez Pass, in a national park, between the volcanoes of Iztaccíhuatl and Popocatépetl, at an altitude of 4010 m, and 60 km to the SE of the center of Mexico City. This region is isolated from local emissions from combustion yet there is a daily incursion of pollution from either the Mexico City basin, when winds are from the west or from the Puebla valley when winds are from the east. This was the motivation for setting up instruments at this site to measure the concentrations of trace gases and the physical, chemical and optical properties of aerosol particles. Measurements were begun during the last week of November, 2005 and continued until early June, 2006. The concentrations of CN, CO2 and CO clearly indicate that the site is in the free troposphere at night and early morning, but the regional boundary layer grows to altitudes above the site every day. Hence, this site is ideal for making observations of atmospheric chemistry at the interface between rural and urban regions. The preliminary analyses have shown that the "free tropospheric" values of CN, particle bound polycyclic aromatic hydrocarbons (PPAH) and black carbon (BC) rarely decrease below 1000 cm-3, 4 ng m-3, 100 ng m-3, respectively, suggesting the presence of a residual layer of contaminants. Nighttime CO and O3 are usually above 0.1 and 0.05 ppm. The CO concentration at the measurement site is a tenth of the Mexico City value and reached its maximum approximately six hours after the maximum in the city center. The maximum O3 in Mexico City and Altzomoni are frequently the same concentration but with no repeatable pattern in the phase differences. The highly linear relationship between BC and CO reflects the removal and dilution processes, i.e. the average ratio between BC and CO in Mexico City is 1000:1 whereas it is 3000:1 in Altzomoni. This relationship also depends on the origin of the boundary layer air, i.e. whether it comes from the east or west

  4. Improvement on the concentrated grape juice physico-chemical characteristics by an enzymatic treatment and Membrane Separation Processes

    Directory of Open Access Journals (Sweden)

    PLÍNIO R.F. CAMPOS

    2016-03-01

    Full Text Available ABSTRACT In this work, the improvement on the concentrated grape juice physico-chemical characteristics by using an enzymatic treatment followed by Membrane Separation Process (MSP has been investigated. By using Novozym 33095(r and Ultrazym AFP L(r enzymes varying three operating parameters, the best result on the grape pulp characteristics was attained for the Novozym 33095(r performed at 35oC, 15 min. and 50 mgL-1. In micro/ultra filtration processes after enzymatic pretreatment, the best performance of the MSP with high permeate flux value and suitable grape juice characteristics was attained using 0.05 mm membrane pore size, 1 bar pressure and 40 oC treatment temperature. When reverse osmosis process is operated at 40 bar and 40oC, high soluble solid and low turbidity values are attained. An enzymatic treatment along with MSP has shown an alternative and efficient grape juice processing system, being possible to extend to other foods.

  5. Concentrations and annual fluxes of sediment-associated chemical constituents from conterminous US coastal rivers using bed sediment data

    Science.gov (United States)

    Horowitz, Arthur J.; Stephens, Verlin C.; Elrick, Kent A.; Smith, James J.

    2012-01-01

    Coastal rivers represent a significant pathway for the delivery of natural and anthropogenic sediment-associated chemical constituents to the Atlantic, Pacific and Gulf of Mexico coasts of the conterminous USA. This study entails an accounting segment using published average annual suspended sediment fluxes with published sediment-associated chemical constituent concentrations for (1) baseline, (2) land-use distributions, (3) population density, and (4) worldwide means to estimate concentrations/annual fluxes for trace/major elements and total phosphorus, total organic and inorganic carbon, total nitrogen, and sulphur, for 131 coastal river basins. In addition, it entails a sampling and subsequent chemical analysis segment that provides a level of ‘ground truth’ for the calculated values, as well as generating baselines for sediment-associated concentrations/fluxes against which future changes can be evaluated. Currently, between 260 and 270 Mt of suspended sediment are discharged annually from the conterminous USA; about 69% is discharged from Gulf rivers (n = 36), about 24% from Pacific rivers (n = 42), and about 7% from Atlantic rivers (n = 54). Elevated sediment-associated chemical concentrations relative to baseline levels occur in the reverse order of sediment discharges:Atlantic rivers (49%)>Pacific rivers (40%)>Gulf rivers (23%). Elevated trace element concentrations (e.g. Cu, Hg, Pb, Zn) frequently occur in association with present/former industrial areas and/or urban centres, particularly along the northeast Atlantic coast. Elevated carbon and nutrient concentrations occur along both the Atlantic and Gulf coasts but are dominated by rivers in the urban northeast and by southeastern and Gulf coast (Florida) ‘blackwater’ streams. Elevated Ca, Mg, K, and Na distributions tend to reflect local petrology, whereas elevated Ti, S, Fe, and Al concentrations are ubiquitous, possibly because they have substantial natural as well as anthropogenic sources

  6. An Assessment of the Model of Concentration Addition for Predicting the Estrogenic Activity of Chemical Mixtures in Wastewater Treatment Works Effluents

    OpenAIRE

    Thorpe, Karen L.; Gross-Sorokin, Melanie; Johnson, Ian; Brighty, Geoff; Tyler, Charles R.

    2005-01-01

    The effects of simple mixtures of chemicals, with similar mechanisms of action, can be predicted using the concentration addition model (CA). The ability of this model to predict the estrogenic effects of more complex mixtures such as effluent discharges, however, has yet to be established. Effluents from 43 U.K. wastewater treatment works were analyzed for the presence of the principal estrogenic chemical contaminants, estradiol, estrone, ethinylestradiol, and nonylphenol. The measured conce...

  7. CHEMICAL ANALYSIS OF REVERSE OSMOSIS MEMBRANE AND XAD RESIN ADSORPTION CONCENTRATES OF WATER DISINFECTED BY CHLORINATION OR OZONATION/CHLORINATION PROCESSES

    Science.gov (United States)

    Chemical Analysis of Reverse Osmosis Membrane and XAD Resin Adsorption Concentrates of Water Disinfected by Chlorination or Ozonation/Chlorination Processes.J. E. Simmons1, S.D. Richardson2, K.M. Schenck3, T. F. Speth3, R. J. Miltner3 and A. D. Thruston21 NHEE...

  8. An assessment of the model of concentration addition for predicting the estrogenic activity of chemical mixtures in wastewater treatment works effluents.

    Science.gov (United States)

    Thorpe, Karen L; Gross-Sorokin, Melanie; Johnson, Ian; Brighty, Geoff; Tyler, Charles R

    2006-04-01

    The effects of simple mixtures of chemicals, with similar mechanisms of action, can be predicted using the concentration addition model (CA). The ability of this model to predict the estrogenic effects of more complex mixtures such as effluent discharges, however, has yet to be established. Effluents from 43 U.K. wastewater treatment works were analyzed for the presence of the principal estrogenic chemical contaminants, estradiol, estrone, ethinylestradiol, and nonylphenol. The measured concentrations were used to predict the estrogenic activity of each effluent, employing the model of CA, based on the relative potencies of the individual chemicals in an in vitro recombinant yeast estrogen screen (rYES) and a short-term (14-day) in vivo rainbow trout vitellogenin induction assay. Based on the measured concentrations of the four chemicals in the effluents and their relative potencies in each assay, the calculated in vitro and in vivo responses compared well and ranged between 3.5 and 87 ng/L of estradiol equivalents (E2 EQ) for the different effluents. In the rYES, however, the measured E2 EQ concentrations in the effluents ranged between 0.65 and 43 ng E2 EQ/L, and they varied against those predicted by the CA model. Deviations in the estimation of the estrogenic potency of the effluents by the CA model, compared with the measured responses in the rYES, are likely to have resulted from inaccuracies associated with the measurement of the chemicals in the extracts derived from the complex effluents. Such deviations could also result as a consequence of interactions between chemicals present in the extracts that disrupted the activation of the estrogen response elements in the rYES. E2 EQ concentrations derived from the vitellogenic response in fathead minnows exposed to a series of effluent dilutions were highly comparable with the E2 EQ concentrations derived from assessments of the estrogenic potency of these dilutions in the rYES. Together these data support the

  9. Relationship between sensitizer concentration and resist performance of chemically amplified extreme ultraviolet resists in sub-10 nm half-pitch resolution region

    Science.gov (United States)

    Kozawa, Takahiro; Santillan, Julius Joseph; Itani, Toshiro

    2017-01-01

    The development of lithography processes with sub-10 nm resolution is challenging. Stochastic phenomena such as line width roughness (LWR) are significant problems. In this study, the feasibility of sub-10 nm fabrication using chemically amplified extreme ultraviolet resists with photodecomposable quenchers was investigated from the viewpoint of the suppression of LWR. The relationship between sensitizer concentration (the sum of acid generator and photodecomposable quencher concentrations) and resist performance was clarified, using the simulation based on the sensitization and reaction mechanisms of chemically amplified resists. For the total sensitizer concentration of 0.5 nm-3 and the effective reaction radius for the deprotection of 0.1 nm, the reachable half-pitch while maintaining 10% critical dimension (CD) LWR was 11 nm. The reachable half-pitch was 7 nm for 20% CD LWR. The increase in the effective reaction radius is required to realize the sub-10 nm fabrication with 10% CD LWR.

  10. Maternal Concentrations of Perfluoroalkyl Substances and Fetal Markers of Metabolic Function and Birth Weight: The Maternal-Infant Research on Environmental Chemicals (MIREC) Study.

    Science.gov (United States)

    Ashley-Martin, Jillian; Dodds, Linda; Arbuckle, Tye E; Bouchard, Maryse F; Fisher, Mandy; Morriset, Anne-Sophie; Monnier, Patricia; Shapiro, Gabriel D; Ettinger, Adrienne S; Dallaire, Renee; Taback, Shayne; Fraser, William; Platt, Robert W

    2017-01-09

    Perfluoroalkyl substances (PFAS) are ubiquitous, persistent chemicals that have been widely used in the production of common household and consumer goods for their nonflammable, lipophobic, and hydrophobic properties. Inverse associations between maternal or umbilical cord blood concentrations of perfluorooctanoic acid and perfluorooctanesulfonate and birth weight have been identified. This literature has primarily examined each PFAS individually without consideration of the potential influence of correlated exposures. Further, the association between PFAS exposures and indicators of metabolic function (i.e., leptin and adiponectin) has received limited attention. We examined associations between first-trimester maternal plasma PFAS concentrations and birth weight and cord blood concentrations of leptin and adiponectin using data on 1,705 mother-infant pairs from the Maternal Infant Research on Environmental Chemicals (MIREC) Study, a trans-Canada birth cohort study that recruited women between 2008 and 2011. Bayesian hierarchical models were used to quantify associations and calculate credible intervals. Maternal perfluorooctanoic acid concentrations were inversely associated with birth weight z score, though the null value was included in all credible intervals (log10 β = -0.10, 95% credible interval: -0.34, 0.13). All associations between maternal PFAS concentrations and cord blood adipocytokine concentrations were of small magnitude and centered around the null value. Follow-up in a cohort of children is required to determine how the observed associations manifest in childhood.

  11. Equilibrium sampling of environmental pollutants in fish: Comparison with lipid- normalized concentrations and homogenization effects on chemical activity

    DEFF Research Database (Denmark)

    Jahnke, Annika; Mayer, Philipp; Adolfsson-Erici, Margaretha;

    2011-01-01

    in the homogenates (statistically significant in 18 of 21 cases, ppartition coefficients determined using tissue......Equilibrium sampling of organic pollutants into the silicone polydimethylsiloxane (PDMS) has recently been applied in biological tissues including fish. Pollutant concentrations in PDMS can then be multiplied with lipid/PDMS distribution coefficients (DLipid,PDMS) to obtain concentrations in fish...

  12. Evaluation of background concentrations of selected chemical and radiochemical constituents in water from the eastern Snake River Plain aquifer at and near the Idaho National Laboratory, Idaho

    Science.gov (United States)

    Bartholomay, Roy C.; L. Flint Hall,

    2016-05-05

    The U.S. Geological Survey and Idaho Department of Environmental Quality Idaho National Laboratory (INL) Oversight Program in cooperation with the U.S. Department of Energy determined background concentrations of selected chemical and radiochemical constituents in the eastern Snake River Plain aquifer to aid with ongoing cleanup efforts at the INL. Chemical and radiochemical constituents including calcium, magnesium, sodium, potassium, silica, chloride, sulfate, fluoride, bicarbonate, chromium, nitrate, tritium, strontium-90, chlorine-36, iodine-129, plutonium-238, plutonium-239, -240 (undivided), americium-241, technetium-99, uranium-234, uranium-235, and uranium-238 were selected for the background study because they were either not analyzed in earlier studies or new data became available to give a more recent determination of background concentrations. Samples of water collected from wells and springs at and near the INL that were not believed to be influenced by wastewater disposal were used to identify background concentrations. Groundwater in the eastern Snake River Plain aquifer at and near the INL was divided into two major water types (western tributary and eastern regional) based on concentrations of lithium less than and greater than 5 micrograms per liter (μg/L). Median concentrations for each constituent were used to define the upper limit of background.

  13. The influence of H2O2 concentration to the structure of silicon nanowire growth by metal-assisted chemical etching

    Science.gov (United States)

    Omar, Hafsa; Jani, Abdul Mutalib Md.; Rusop, Mohamad; Abdullah, Saifollah

    2016-07-01

    A simple and low cost method to produce well aligned silicon nanowires at large areas using Ag-assisted chemical etching at room temperature were presented. The structure of silicon nanowires growth by metal-assisted chemical etching was observed. Prior to the etching, the silicon nanowires were prepared by electroless metal deposited (EMD) in solution containing hydrofluoric acid and hydrogen peroxide in Teflon vessel. The silver particle was deposited on substrate by immersion in hydrofluoric acid and silver nitrate solution for sixty second. The silicon nanowires were growth in different hydrogen peroxide concentration which are 0.3M, 0.4M, 0.5M and 0.6M and 0.7M.The influence of hydrogen peroxide concentration to the formation of silicon nanowires was studied. The morphological properties of silicon nanowires were investigated using field emission scanning electron microscopy (FESEM) and Energy Dispersive X-Ray Spectroscopy (EDS).

  14. Influence of ethanol concentration, addition of spices extract, and level of sweetness on physico-chemical characteristics and sensory quality of apple vermouth

    OpenAIRE

    2000-01-01

    The composition of apple base wine was found to be suitable for conversion into vermouth. The spices extract contained more TSS, tannins, esters, volatile acid but lower titrable acid than apple base wine. To optimize and develop apple vermouth with different ethanol concentrations (12%, 15%, 18%), sugar content (4%, 8%) and spices extract (2.5% and 5.0%) was prepared and was evaluated. Significant differences in physico-chemical characteristics and sensory quality amongst the vermouths havin...

  15. Measuring binding and speciation of hydrophobic organic chemicals at controlled freely dissolved concentrations and without phase separation

    DEFF Research Database (Denmark)

    Gouliarmou, Varvara; Smith, K E C; de Jonge, Lis Wollesen

    2012-01-01

    , and simple linear regression provided precise partition ratios, salting out constants, and critical micelle concentrations. These parameters were generally in good agreement with published values obtained by solid phase microextraction and fluorescence quenching. The very good precision was indicated...

  16. [Effects of Different Modifier Concentrations on Lead-Zinc Tolerance, Subcellular Distribution and Chemical Forms for Four Kinds of Woody Plants].

    Science.gov (United States)

    Chen, Yong-hua; Zhang, Fu-yun; Wu, Xiao-fu; Liang, Xi; Yuan, Si-wen

    2015-10-01

    Four kinds of lead-zinc tolerant woody plants: Nerium oleander, Koelreuteria paniculata, Paulownia and Boehmeria were used as materials to estimate their enrichment and transferable capacity of lead (Pb) and zinc (Zn) and analyze the subcellular distribution and chemical speciation of Zn and Ph in different parts of plants, under different modifier concentrations (CK group: 100% lead-zinc slag plus a small amount of phosphate fertilizer, improved one: 85% of lead-zinc slag ± 10% peat ± 5% bacterial manure plus a small amount of phosphate fertilizer, improved two: 75% lead-zinc slag ± 20% peat ± 5% bacterial manure ± a small amount of phosphate). Results showed that: (1) The content of Pb, Zn in matrix after planting four kinds of plants was lower than before, no significant difference between improved one and improved two of Nerium oleander and Boehmeria was found, but improved two was better than improved one of Paulownia, while improved one was better than improved two of Koelreuteria paniculata; Four plants had relatively low aboveground enrichment coefficient of Pb and Zn, but had a high transfer coefficient, showed that the appropriate modifier concentration was able to improve the Pb and Zn enrichment and transfer ability of plants. (2) In subcellular distribution, most of Pb and Zn were distributed in plant cell wall components and soluble components while the distribution in cell organelles such as mitochondria, chloroplasts and nucleus component were less. Compared with CK group, two improved group made soluble components of the cell walls of Pb fixation and retention of zinc role in the enhancement. (3) As for the chemical forms of Pb and Zn in plants, the main chemical forms of Pb were hydrochloric acid, sodium chloride and ethanol extractable forms, while other chemical form contents were few, the main chemical forms of Zn were different based on plant type. Compared with CK group, the proportion of the active Pb chemical form in different plant

  17. Iontophoretic transdermal delivery of glycyrrhizin: effects of pH, drug concentration, co-ions, current intensity, and chemical enhancers.

    Science.gov (United States)

    Yamamoto, Rie; Takasuga, Shinri; Kominami, Katsuya; Sutoh, Chiyo; Kinoshita, Mine; Kanamura, Kiyoshi; Takayama, Kozo

    2013-01-01

    The aim of the present study was to evaluate the feasibility of transdermal delivery of glycyrrhizin, an agent used in the treatment of chronic hepatitis C, by cathodal iontophoresis using Ag/AgCl electrodes in vitro. The effects of donor pH (pH 4-7), concentration of drug (0.025-0.2% (w/v)), concentration of external chloride ions (Cl(-)) (0-133 mM), current strength (0-0.5 mA/cm(2)), and permeation enhancers (urea and Tween 80) on the skin permeability of glycyrrhizin were examined in in vitro skin permeation studies using porcine ear skin as the membrane. The cumulative amount of permeated glycyrrhizin and the steady-state skin permeation flux of glycyrrhizin across porcine skin increased in a pH-dependent manner. The skin permeability of glycyrrhizin was independent of the concentration of drug and competed only with a high external Cl(-) concentration. The skin permeation flux of glycyrrhizin increased with the current (R(2)=0.8955). The combination of iontophoresis and enhancers provided an additive or synergistic effect, and a skin permeation flux of about 60 µg/h/cm(2) was achieved. The plasma concentration of glycyrrhizin in humans, extrapolated from the in vitro steady-state permeation flux across porcine skin, was within the therapeutic level. These results suggest that cathodal iontophoresis can be used as a transdermal drug delivery system for glycyrrhizin using reasonable patch sizes and acceptable levels of current intensity.

  18. Physiological and chemical characteristics of safflower (Carthamus tinctorius L. grown in the presence of low salt concentrations

    Directory of Open Access Journals (Sweden)

    Daničić Milena M.

    2016-01-01

    Full Text Available (Carthamus tinctorius L. is highly regarded in the world as an aromatic, spicy, medicinal and oilseed crop, which can be used in all kinds of industries. It inhabits arid and semiarid areas of the world. The influence of the relatively low NaCl concentrations found in soils and irrigation waters on the growth and metabolism of saf­flower, grown under semi-controlled conditions, was examined in this work. It was found that increased concentrations of NaCl affected the number of leaves per plant and dry leaves mass/area ratio. The transpiration intensity was reduced in plants grown in the presence of NaCl and stomatal diffusive resistance increased following an increase in NaCl concentration.

  19. 关于新建炉EDTA低浓度清洗的探讨%Discussions on chemical cleaning of new boiler with low concentration EDTA

    Institute of Scientific and Technical Information of China (English)

    饶勇

    2012-01-01

    This thesis expounds the basic principles of cleaning boiler with EDTA, and technics, methods, controlling main points for the chemical cleaning of new boiler with low concentration EDTA. By comparing the economical efficiency between low concentration EDTA cleaning and coordination EDTA cleaning, it is provided the direction for the low concentration EDTA cleaning.%阐述了EDTA清洗锅炉的基本原理,低浓度清洗新建炉的工艺、方法及控制要点,EDTA低浓度清洗与协调EDTA清洗的经济性比较,为新建炉EDTA低浓度清洗探索了方向。

  20. Effect of repeated and prolonged exposure to low concentrations of Low Molecular Weight chemicals on local lymph node responses

    NARCIS (Netherlands)

    Jong WH de; Beek M ter; Veenman C; Klerk A de; Loveren H van; TOX

    2006-01-01

    The results of the local lymph node assay are not for all compounds useful as starting point for a quantitative risk assessment. This study describes the effects after repeated exposure of the skin to a concentration of a sensitizer below the threshold used in the local lymph node assay. Positive re

  1. Atmospheric mercury concentration and chemical speciation at a rural site in Beijing, China: implications of mercury emission sources

    Directory of Open Access Journals (Sweden)

    L. Zhang

    2013-10-01

    Full Text Available Continuous measurements of atmospheric mercury concentration and speciation play a key role in identifying mercury sources and its behavior in the atmosphere. In this study, speciated atmospheric mercury including gaseous elemental mercury (GEM, reactive gaseous mercury (RGM and particle-bound mercury (PBM were continuously measured at Miyun, a rural site in Beijing, China, from December 2008 to November 2009. The average GEM, RGM and PBM concentrations were found to be 3.22 ± 1.74, 10.1 ± 18.8 and 98.2 ± 112.7 pg m−3, respectively, about 2–20 times higher than the background concentration of the Northern Hemisphere. The results indicated that atmospheric mercury concentrations in northern China were highly affected by anthropogenic emissions. The atmospheric mercury showed obvious seasonal variations, with the highest seasonal average GEM concentration in summer (3.48 ng m−3 and the lowest value in winter (2.66 ng m−3. In autumn and winter a diurnal variation of GEM was observed, with peak levels in the late afternoon till midnight. Most of the high RGM concentration values occurred in the afternoon of all seasons due to the higher oxidation. The PBM concentration was higher in early morning of all seasons because of the the temperature inversion that increases in depth as the night proceeds. The ratio of GEM to CO indicates that residential boilers play an important role in the elevation of GEM in winter. The ratio of RGM to O3 could be an indicator of the contribution of local primary sources. The ratio of PBM to PM2.5 reveals that the air mass from the east and southwest of the site in spring and summer carries more atmospheric mercury. The HYSPLIT back-trajectory analysis indicated that the monitoring site is affected by local, regional and interregional sources simultaneously during heavy pollution episodes. The results from the potential source contribution function (PSCF model indicate that the atmospheric transport

  2. Evaluation of the laser-induced breakdown spectroscopy technique for determination of the chemical composition of copper concentrates

    Energy Technology Data Exchange (ETDEWEB)

    Łazarek, Łukasz, E-mail: lukasz.lazarek@pwr.wroc.pl [Laser and Fiber Electronics Group, Faculty of Electronics, Wroclaw University of Technology, Wyb. Wyspianskiego 27, 50-370 Wroclaw (Poland); Antończak, Arkadiusz J.; Wójcik, Michał R. [Laser and Fiber Electronics Group, Faculty of Electronics, Wroclaw University of Technology, Wyb. Wyspianskiego 27, 50-370 Wroclaw (Poland); Drzymała, Jan [Faculty of Geoengineering, Mining and Geology, Wroclaw University of Technology, Wyb. Wyspianskiego 27, 50-370 Wroclaw (Poland); Abramski, Krzysztof M. [Laser and Fiber Electronics Group, Faculty of Electronics, Wroclaw University of Technology, Wyb. Wyspianskiego 27, 50-370 Wroclaw (Poland)

    2014-07-01

    Laser-induced breakdown spectroscopy (LIBS), like many other spectroscopic techniques, is a comparative method. Typically, in qualitative analysis, synthetic certified standard with a well-known elemental composition is used to calibrate the system. Nevertheless, in all laser-induced techniques, such calibration can affect the accuracy through differences in the overall composition of the chosen standard. There are also some intermediate factors, which can cause imprecision in measurements, such as optical absorption, surface structure and thermal conductivity. In this work the calibration performed for the LIBS technique utilizes pellets made directly from the tested materials (old well-characterized samples). This choice produces a considerable improvement in the accuracy of the method. This technique was adopted for the determination of trace elements in industrial copper concentrates, standardized by conventional atomic absorption spectroscopy with a flame atomizer. A series of copper flotation concentrate samples was analyzed for three elements: silver, cobalt and vanadium. We also proposed a method of post-processing the measurement data to minimize matrix effects and permit reliable analysis. It has been shown that the described technique can be used in qualitative and quantitative analyses of complex inorganic materials, such as copper flotation concentrates. It was noted that the final validation of such methodology is limited mainly by the accuracy of the characterization of the standards. - Highlights: • A laser-induced breakdown spectroscopy technique is introduced for composition monitoring in industrial copper concentrates. • Calibration samples consisted of pellets produced from the tested materials. • The proposed method of post-processing significantly minimizes matrix effects. • The possible uses of this technique are limited mainly by accurate characterization of the standard samples.

  3. Development of a virus concentration method using lanthanum-based chemical flocculation coupled with modified membrane filtration procedures.

    Science.gov (United States)

    Zhang, Yanyan; Riley, Lela K; Lin, Mengshi; Purdy, Gregory A; Hu, Zhiqiang

    2013-06-01

    Direct membrane filtration is often used to concentrate viruses in water but it may suffer from severe membrane fouling and clogging. Here, a lanthanum-based flocculation method coupled with modified membrane filtration procedures was developed and evaluated to detect viruses in large volume (40 L) water samples. The lanthanum-based flocculation method could easily reduce the water sample volume by a factor of 40. Additional volume reduction was achieved by a two-step membrane filtration approach. First, selected membrane filters (including 1MDS electropositive filters and nitrocellulose electronegative filters-Millipore HATF filters) were used to reduce water sample volume further and compare their efficiencies in virus recovery. The Mg²⁺-modified HATF membrane performed better on MS2 retention with an average virus recovery of 83.4% (±4.5% [standard deviation]). After HATF membrane filtration and elution, centrifugal ultrafiltration through a 30 kDa cut-off membrane resulted in an overall concentration factor of 20,000. Results from the infectivity assay showed that the MS2 recovery efficiencies from the NanoCeram- and 1MDS-based direct filtration and the lanthanum-based concentration coupled with the modified filtration procedure were 10.1% (±1.0%), 3.3% (±0.1%), and 17.5% (±1.1%), respectively. Results from the PCR analysis showed that the virus recoveries of the lanthanum-based method were 20.6% (±2.9%) and 19.5% (±3.4%) for MS2 and adenovirus, respectively, while no adenovirus could be detected through the NanoCeram- and 1MDS-based direct filtration. The lanthanum-based concentration method coupled with modified membrane filtration procedures is therefore a promising method for detecting waterborne viruses.

  4. Design of a New Concentration Series for the Orthogonal Sample Design Approach and Estimation of the Number of Reactions in Chemical Systems.

    Science.gov (United States)

    Shi, Jiajia; Liu, Yuhai; Guo, Ran; Li, Xiaopei; He, Anqi; Gao, Yunlong; Wei, Yongju; Liu, Cuige; Zhao, Ying; Xu, Yizhuang; Noda, Isao; Wu, Jinguang

    2015-11-01

    A new concentration series is proposed for the construction of a two-dimensional (2D) synchronous spectrum for orthogonal sample design analysis to probe intermolecular interaction between solutes dissolved in the same solutions. The obtained 2D synchronous spectrum possesses the following two properties: (1) cross peaks in the 2D synchronous spectra can be used to reflect intermolecular interaction reliably, since interference portions that have nothing to do with intermolecular interaction are completely removed, and (2) the two-dimensional synchronous spectrum produced can effectively avoid accidental collinearity. Hence, the correct number of nonzero eigenvalues can be obtained so that the number of chemical reactions can be estimated. In a real chemical system, noise present in one-dimensional spectra may also produce nonzero eigenvalues. To get the correct number of chemical reactions, we classified nonzero eigenvalues into significant nonzero eigenvalues and insignificant nonzero eigenvalues. Significant nonzero eigenvalues can be identified by inspecting the pattern of the corresponding eigenvector with help of the Durbin-Watson statistic. As a result, the correct number of chemical reactions can be obtained from significant nonzero eigenvalues. This approach provides a solid basis to obtain insight into subtle spectral variations caused by intermolecular interaction.

  5. Modelling the physico-chemical effect of silver electrorefining as effect of temperature, free acid, silver, copper and lead concentrations

    Science.gov (United States)

    Aji, Arif T.; Kalliomäki, Taina; Wilson, Benjamin P.; Aromaa, Jari; Lundström, Mari

    2017-01-01

    The study of electrolyte bath properties is essential for the improvement of silver electrolysis based processes. The paper outlines investigations into suitable models for the calculation of physico-chemical properties with the emphasis placed on conductivity, density and viscosity. Measurements were conducted within the industrial operation parameters used for silver electrolytes and the results indicate that these type of industrial electrolytes have an operating conductivity within the range of 60-140 mS/cm, density of 1.05-1.14 g/cm3 and a viscosity of 0.75-0.91 mm2/s. A representative model for each of these properties was proposed in order to calculate the conductivity, density and viscosity of silver electrolyte. From the evaluation of models, it was determined that all models have R2 (accuracy of fit) and Q2 (accuracy of prediction) values above 0.9 and thus can be regarded as excellent models.

  6. Simplified quantification of labile proton concentration-weighted chemical exchange rate (k(ws) ) with RF saturation time dependent ratiometric analysis (QUESTRA): normalization of relaxation and RF irradiation spillover effects for improved quantitative chemical exchange saturation transfer (CEST) MRI.

    Science.gov (United States)

    Sun, Phillip Zhe

    2012-04-01

    Chemical exchange saturation transfer MRI is an emerging imaging technique capable of detecting dilute proteins/peptides and microenvironmental properties, with promising in vivo applications. However, chemical exchange saturation transfer MRI contrast is complex, varying not only with the labile proton concentration and exchange rate, but also with experimental conditions such as field strength and radiofrequency (RF) irradiation scheme. Furthermore, the optimal RF irradiation power depends on the exchange rate, which must be estimated in order to optimize the chemical exchange saturation transfer MRI experiments. Although methods including numerical fitting with modified Bloch-McConnell equations, quantification of exchange rate with RF saturation time and power (QUEST and QUESP), have been proposed to address this relationship, they require multiple-parameter non-linear fitting and accurate relaxation measurement. Our work extended the QUEST algorithm with ratiometric analysis (QUESTRA) that normalizes the magnetization transfer ratio at labile and reference frequencies, which effectively eliminates the confounding relaxation and RF spillover effects. Specifically, the QUESTRA contrast approaches its steady state mono-exponentially at a rate determined by the reverse exchange rate (k(ws) ), with little dependence on bulk water T(1) , T(2) , RF power and chemical shift. The proposed algorithm was confirmed numerically, and validated experimentally using a tissue-like phantom of serially titrated pH compartments.

  7. Feeding on Host Plants with Different Concentrations and Structures of Pyrrolizidine Alkaloids Impacts the Chemical-Defense Effectiveness of a Specialist Herbivore

    Science.gov (United States)

    Cunha, Beatriz P.; Solferini, Vera N.

    2015-01-01

    Sequestration of chemical defenses from host plants is a strategy widely used by herbivorous insects to avoid predation. Larvae of the arctiine moth Utetheisa ornatrix feeding on unripe seeds and leaves of many species of Crotalaria (Leguminosae) sequester N-oxides of pyrrolizidine alkaloids (PAs) from these host plants, and transfer them to adults through the pupal stage. PAs confer protection against predation on all life stages of U. ornatrix. As U. ornatrix also uses other Crotalaria species as host plants, we evaluated whether the PA chemical defense against predation is independent of host plant use. We fed larvae from hatching to pupation with either leaves or seeds of one of eight Crotalaria species (C. incana, C. juncea, C. micans, C. ochroleuca, C. pallida, C. paulina, C. spectabilis, and C. vitellina), and tested if adults were preyed upon or released by the orb-weaving spider Nephila clavipes. We found that the protection against the spider was more effective in adults whose larvae fed on seeds, which had a higher PA concentration than leaves. The exceptions were adults from larvae fed on C. paulina, C. spectabilis and C. vitellina leaves, which showed high PA concentrations. With respect to the PA profile, we describe for the first time insect-PAs in U. ornatrix. These PAs, biosynthesized from the necine base retronecine of plant origin, or monocrotaline- and senecionine-type PAs sequestered from host plants, were equally active in moth chemical defense, in a dose-dependent manner. These results are also partially explained by host plant phylogeny, since PAs of the host plants do have a phylogenetic signal (clades with high and low PA concentrations in leaves) which is reflected in the adult defense. PMID:26517873

  8. Feeding on Host Plants with Different Concentrations and Structures of Pyrrolizidine Alkaloids Impacts the Chemical-Defense Effectiveness of a Specialist Herbivore.

    Directory of Open Access Journals (Sweden)

    Carlos H Z Martins

    Full Text Available Sequestration of chemical defenses from host plants is a strategy widely used by herbivorous insects to avoid predation. Larvae of the arctiine moth Utetheisa ornatrix feeding on unripe seeds and leaves of many species of Crotalaria (Leguminosae sequester N-oxides of pyrrolizidine alkaloids (PAs from these host plants, and transfer them to adults through the pupal stage. PAs confer protection against predation on all life stages of U. ornatrix. As U. ornatrix also uses other Crotalaria species as host plants, we evaluated whether the PA chemical defense against predation is independent of host plant use. We fed larvae from hatching to pupation with either leaves or seeds of one of eight Crotalaria species (C. incana, C. juncea, C. micans, C. ochroleuca, C. pallida, C. paulina, C. spectabilis, and C. vitellina, and tested if adults were preyed upon or released by the orb-weaving spider Nephila clavipes. We found that the protection against the spider was more effective in adults whose larvae fed on seeds, which had a higher PA concentration than leaves. The exceptions were adults from larvae fed on C. paulina, C. spectabilis and C. vitellina leaves, which showed high PA concentrations. With respect to the PA profile, we describe for the first time insect-PAs in U. ornatrix. These PAs, biosynthesized from the necine base retronecine of plant origin, or monocrotaline- and senecionine-type PAs sequestered from host plants, were equally active in moth chemical defense, in a dose-dependent manner. These results are also partially explained by host plant phylogeny, since PAs of the host plants do have a phylogenetic signal (clades with high and low PA concentrations in leaves which is reflected in the adult defense.

  9. Feeding on Host Plants with Different Concentrations and Structures of Pyrrolizidine Alkaloids Impacts the Chemical-Defense Effectiveness of a Specialist Herbivore.

    Science.gov (United States)

    Martins, Carlos H Z; Cunha, Beatriz P; Solferini, Vera N; Trigo, José R

    2015-01-01

    Sequestration of chemical defenses from host plants is a strategy widely used by herbivorous insects to avoid predation. Larvae of the arctiine moth Utetheisa ornatrix feeding on unripe seeds and leaves of many species of Crotalaria (Leguminosae) sequester N-oxides of pyrrolizidine alkaloids (PAs) from these host plants, and transfer them to adults through the pupal stage. PAs confer protection against predation on all life stages of U. ornatrix. As U. ornatrix also uses other Crotalaria species as host plants, we evaluated whether the PA chemical defense against predation is independent of host plant use. We fed larvae from hatching to pupation with either leaves or seeds of one of eight Crotalaria species (C. incana, C. juncea, C. micans, C. ochroleuca, C. pallida, C. paulina, C. spectabilis, and C. vitellina), and tested if adults were preyed upon or released by the orb-weaving spider Nephila clavipes. We found that the protection against the spider was more effective in adults whose larvae fed on seeds, which had a higher PA concentration than leaves. The exceptions were adults from larvae fed on C. paulina, C. spectabilis and C. vitellina leaves, which showed high PA concentrations. With respect to the PA profile, we describe for the first time insect-PAs in U. ornatrix. These PAs, biosynthesized from the necine base retronecine of plant origin, or monocrotaline- and senecionine-type PAs sequestered from host plants, were equally active in moth chemical defense, in a dose-dependent manner. These results are also partially explained by host plant phylogeny, since PAs of the host plants do have a phylogenetic signal (clades with high and low PA concentrations in leaves) which is reflected in the adult defense.

  10. The long shadow of our chemical past - High DDT concentrations in fish near a former agrochemicals factory in England.

    Science.gov (United States)

    Jürgens, Monika D; Crosse, John; Hamilton, Patrick B; Johnson, Andrew C; Jones, Kevin C

    2016-11-01

    A total of 81 roach (Rutilus rutilus) collected from 13 southern English river sites between 2007 and 2012, were analysed for organochlorine pesticides, PCBs, PBDEs and some metals. Unexpectedly high concentrations of the banned insecticide DDT and its degradation products DDE and DDD (∑DDTs) were found in the 10 fish from the river Lee (or Lea) which averaged 88 ± 70 (standard deviation) μg/kg ww, almost 20 times higher than the average for the remaining sites (4.8 ± 3.1 μg/kg). All fish from that site exceeded the Canadian Tissue Residue Guideline (environmental quality standard) of 14 μg/kg ∑DDTs. Concentrations of the insecticides chlordane and lindane as well as copper, which is often used as a fungicide, were also elevated in fish from the Lee, though not as much as those of DDTs. A likely explanation for these observations was found in a nearby former pesticide factory, which had stopped production about three decades earlier. An extensive review of recent literature data on DDT in wild European fish found that, while levels are now generally low, there were several other hotspots with ∑DDTs levels that may still be of concern.

  11. Concentration and chemical composition of PM10 particles in the metropolitan area of ​Costa Rica in 2012

    Directory of Open Access Journals (Sweden)

    Jorge Herrera

    2014-12-01

    Full Text Available During 2012 the PM10 concentrations were measured in 13 sampling sites distributed in the metropolitan area of Costa Rica. The samples were collected using high volume samplers and subsequently analyzed for: ions (F-, Cl-, NO2-, NO3-, PO43-, SO42-, trace metals (V, Cr, Cu, Mn, Fe, Al, Pb, Ni, organic and elemental carbon content. Sampling sites located in high traffic commercial and industrial zones exhibited significative increased concentrations (42 – 29 µg/m3 compared to low traffic commercial and residential zones (23 – 15 µg/m3. As for speciation, crustal contribution increases from 13-14 % found in high traffic industrial zones to 28 % in residential zones. While marine aerosol contribution ranges from 2,5 to 5% for all sampling sites without a distinctive pattern. The OC and EC fraction was the most important contribution to the PM10 composition, mainly in HE-01 and BE-01 sampling sites accounting for around 53 and 56 % of the total mass. This reflects the importance of combustion sources to the fine particulate matter composition. In the case of the trace metals fraction it was the lowest one found for all the sampling sites.

  12. A fire-assay and wet chemical method for the determination of palladium, platinum, gold, and silver in ores and concentrates.

    Science.gov (United States)

    Moloughney, P E

    1980-04-01

    A method is presented for the determination of palladium, platinum, gold and silver in ores and concentrates by a fire-assay and wet chemical technique. After parting of the lead assay button with dilute nitric acid, and separation of the solution from the residue, the palladium and platinum in the solution are precipitated by the addition of stannous chloride, with tellurium as collector. The resulting precipitate is combined with the gold residue and dissolved in aqua regia, then the solution is analysed for palladium, platinum and gold by atomic-absorption spectrophotometry (AAS). Silver is determined in the original solution by AAS before the reduction step.

  13. Chemical, technological and in vitro antioxidant properties of mango, guava, pineapple and passion fruit dietary fibre concentrate.

    Science.gov (United States)

    Martínez, Ruth; Torres, Paulina; Meneses, Miguel A; Figueroa, Jorge G; Pérez-Álvarez, José A; Viuda-Martos, Manuel

    2012-12-01

    The aim of this work was to determine the chemical, technological and in vitro antioxidant properties of co-products from the industrialisation of some tropical exotic fruits, such as mango, pineapple, guava and passion fruit, and to evaluate their potential use as dietary fibre sources for food enrichment. Proximate compositions were determined, as well as the total, insoluble and soluble fibre contents. The water holding, oil holding and swelling capacities were also determined. For the antioxidant activity, three different test systems were used (ABTS, DPPH and FRAP). The dietary fibre content of the co-products varied in a range between 69.1 and 81.5g/100g on a dry matter basis with a good balanced ratio between insoluble dietary fibre and soluble dietary fibre. Phenol recovery was dependent on the fruit type and the solvent system used. Methanol:acetone was a more efficient solvent for extracting phenols than ethanol. There was a good correlation between total phenol content and antioxidant capacity of the fruit extracts. All samples analysed had good antioxidant capacity. The results of this study indicate that exotic fruit fibres obtained as co-products in the process to obtain juice may be considered a good source of natural compounds with significant antioxidant activity.

  14. Shake-flask test for determination of biodegradation rates of 14C-labelled chemicals at low concentrations in surface water systems

    DEFF Research Database (Denmark)

    Ingerslev, F.; Nyholm, Niels

    2000-01-01

    A simple shake-flask surface water biodegradability die away test with C-14-labeled chemicals added to microgram per liter concentrations (usually 1-100 mu g/L) is described and evaluated. The aim was to provide information on biodegradation behavior and kinetic rates at environmental (low......) concentrations in surface water systems. The basic principle of measurement was to determine evolved CO2 indirectly from measurements of total organic activity in subsamples after stripping off their content of CO2, Used with surface water alone the test simulates a pelagic environment and amended with sediments...... regular reinoculation with freshly collected surface water could, however, overcome the problems of false-negative results. (C) 2000 Academic Press....

  15. The Concentration Probability Density Function With Implications for Probabilistic Modeling of Chemical Warfare Agent Detector Responses for Source Reconstruction

    Science.gov (United States)

    2008-05-01

    probabiliste concernant la réponse du détecteur d’agents chimiques , dans le contexte du problème de la reconstruction de source. ii DRDC Suffield TR 2008...quantité d’agent émis et l’heure de l’émission détectée par un réseau de capteurs CBR. Pour être en mesure de combler cette lacune, le Programme de...tions CBR provenant de réseaux de capteurs éloignés pouvant être déployés et ayant des données de modèles de concentrations obtenues par des

  16. Chemical characteristics of dissolved organic matter (DOM) in relation to heavy metal concentrations in soil water from boreal peatlands after clear-cut harvesting

    Science.gov (United States)

    Kiikkilä, O.; Nieminen, T.; Starr, M.; Ukonmaanaho, L.

    2012-04-01

    Boreal peatlands form an important terrestrial carbon reserve and are a major source of dissolved organic matter (DOM) to surface waters, particularly when disturbed through forestry practices such as draining or timber harvesting. Heavy metals show a strong affinity to organic matter and so, along with DOM, heavy metals can be mobilized and transported from the soil to surface waters and sediments where they may become toxic to aquatic organisms and pass up the food chain. The complexation of heavy metals with DOM can be expected to be related and determined by the chemical characteristics of DOM and oxidation/reducing conditions in the peat. We extracted interstitial water from peat samples and determined the concentrations of dissolved organic carbon (DOC), dissolved organic nitrogen (DON) and Al, Cu, Zn and Fe in various fractions of DOM isolated by adsorption properties (XAD-8 fractionation) and molecular-weight (ultrafiltration). The peat samples were taken from 0-30 and 30-50 cm depth in drained peatland catchments two years after whole-tree or stem-only clear-cut harvesting (Scots pine or Norway spruce) had been carried out. The samples from the upper layer had been subject to alternating saturation/aeration conditions while the deeper layer had been continuously under the water table. The fractionation of DOC and DON according to both adsorption properties and molecular-weight fractions clearly differed between the upper and lower peat layers. While the hydrophobic acid fraction contained proportionally more DOC and DON than the hydrophilic acid fraction in the upper peat layer the results were vice versa in the lower peat layer. High-molecular-weight compounds (> 100 kDa) were proportionally more abundant in the upper and low-molecular-weight compounds (< 1 kDa) in the lower peat layer. These differences are assumed to reflect differences in the aerobic/ anaerobic conditions and degree of decomposition between the two layers. The concentrations of Zn, Al

  17. Thermodynamic Modeling of the Solubility and Chemical Speciation of Mercury and Methylmercury Driven by Organic Thiols and Micromolar Sulfide Concentrations in Boreal Wetland Soils.

    Science.gov (United States)

    Liem-Nguyen, Van; Skyllberg, Ulf; Björn, Erik

    2017-03-15

    Boreal wetlands have been identified as environments in which inorganic divalent mercury (Hg(II)) is transformed to methylmercury (MeHg) by anaerobic microbes. In order to understand this transformation and the mobility and transport of Hg(II) and MeHg, factors and conditions in control of the solubility and chemical speciation of Hg(II) and MeHg need to be clarified. Here we explore the ability of thermodynamic models to simulate measured solubility of Hg(II) and MeHg in different types of boreal wetland soils. With the input of measured concentrations of MeHg, sulfide, eight low molecular mass thiols and thiol groups associated with natural organic matter (NOM), as determined by sulfur K-edge X-ray absorption near-edge structure (XANES) spectroscopy and Hg LIII-edge extended X-ray absorption fine structure spectroscopy (EXAFS), the model could accurately predict porewater concentrations of MeHg in the wetlands. A similar model for Hg(II) successfully predicted the average level of its concentration in the porewaters, but the variability among samples, driven mainly by the concentration of aqueous inorganic sulfide, was predicted to be larger than measurements. The smaller than predicted variability in Hg(II) solubility is discussed in light of possible formation of colloidal HgS(s) passing the 0.22 μm filters used to define the aqueous phase. The chemical speciation of the solid/adsorbed and aqueous phases were dominated by NOM associated thiol complexes for MeHg and by an equal contribution from NOM associated thiols and HgS(s) for Hg(II).

  18. Predicted no effect concentration derivation as a significant source of variability in environmental hazard assessments of chemicals in aquatic systems: an international analysis.

    Science.gov (United States)

    Hahn, Thorsten; Diamond, Jerry; Dobson, Stuart; Howe, Paul; Kielhorn, Janet; Koennecker, Gustav; Lee-Steere, Chris; Mangelsdorf, Inge; Schneider, Uwe; Sugaya, Yoshio; Taylor, Ken; Dam, Rick Van; Stauber, Jenny L

    2014-01-01

    Environmental hazard assessments for chemicals are carried out to define an environmentally "safe" level at which, theoretically, the chemical will not negatively affect any exposed biota. Despite this common goal, the methodologies in use are very diverse across different countries and jurisdictions. This becomes particularly obvious when international scientists work together on documents with global scope, e.g., in the World Health Organization (WHO) International Program on Chemical Safety. In this article, we present a study that describes the extent of such variability and analyze the reasons that lead to different outcomes in deriving a "safe level" (termed the predicted no effect concentration [PNEC] throughout this article). For this purpose, we chose 5 chemicals to represent well-known substances for which sufficient high-quality aquatic effects data were available: ethylene glycol, trichloroethylene, nonylphenol, hexachlorobenzene, and copper (Cu). From these data, 2 data sets for each chemical were compiled: the full data set, that contained all information from selected peer-review sources, and the base data set, a subsample of the full set simulating limited data. Scientists from the European Union (EU), United States, Canada, Japan, and Australia independently carried out hazard assessments for each of these chemicals using the same data sets. Their reasoning for key study selection, use of assessment factors, or use of probabilistic methods was comprehensively documented. The observed variation in the PNECs for all chemicals was up to 3 orders of magnitude, and this was not simply due to obvious factors such as the size of the data set or the methodology used. Rather, this was due to individual decisions of the assessors within the scope of the methodology used, especially key study selection, acute versus chronic definitions, and size of assessment factors. Awareness of these factors, together with transparency of the decision-making process, would

  19. Hole traps associated with high-concentration residual carriers in p-type GaAsN grown by chemical beam epitaxy

    Energy Technology Data Exchange (ETDEWEB)

    Elleuch, Omar, E-mail: mr.omar.elleuch@gmail.com; Wang, Li; Lee, Kan-Hua; Demizu, Koshiro; Ikeda, Kazuma; Kojima, Nobuaki; Ohshita, Yoshio; Yamaguchi, Masafumi [Toyota Technological Institute, 2-12-1 Hisakata, Tempaku, Nagoya 468-8511 (Japan)

    2015-01-28

    The hole traps associated with high background doping in p-type GaAsN grown by chemical beam epitaxy are studied based on the changes of carrier concentration, junction capacitance, and hole traps properties due to the annealing. The carrier concentration was increased dramatically with annealing time, based on capacitance–voltage (C–V) measurement. In addition, the temperature dependence of the junction capacitance (C–T) was increased rapidly two times. Such behavior is explained by the thermal ionization of two acceptor states. These acceptors are the main cause of high background doping in the film, since the estimated carrier concentration from C–T results explains the measured carrier concentration at room temperature using C–V method. The acceptor states became shallower after annealing, and hence their structures are thermally unstable. Deep level transient spectroscopy (DLTS) showed that the HC2 hole trap was composed of two signals, labeled HC21 and HC22. These defects correspond to the acceptor levels, as their energy levels obtained from DLTS are similar to those deduced from C–T. The capture cross sections of HC21 and HC22 are larger than those of single acceptors. In addition, their energy levels and capture cross sections change in the same way due to the annealing. This tendency suggests that HC21 and HC22 signals originate from the same defect which acts as a double acceptor.

  20. Improved measurement of labile proton concentration-weighted chemical exchange rate (k(ws)) with experimental factor-compensated and T(1) -normalized quantitative chemical exchange saturation transfer (CEST) MRI.

    Science.gov (United States)

    Wu, Renhua; Liu, Charng-Ming; Liu, Philip K; Sun, Phillip Zhe

    2012-01-01

    Chemical exchange saturation transfer (CEST) MRI enables measurement of dilute CEST agents and microenvironment properties such as pH and temperature, holding great promise for in vivo applications. However, because of confounding concomitant radio frequency (RF) irradiation and relaxation effects, the CEST-weighted MRI contrast may not fully characterize the underlying CEST phenomenon. We postulated that the accuracy of quantitative CEST MRI could be improved if the experimental factors (labeling efficiency and RF spillover effect) were estimated and taken into account. Specifically, the experimental factor was evaluated as a function of exchange rate and CEST agent concentration ratio, which remained relatively constant for intermediate RF irradiation power levels. Hence, the experimental factors can be calculated based on the reasonably estimated exchange rate and labile proton concentration ratio, which significantly improved quantification. The simulation was confirmed with creatine phantoms of serially varied concentration titrated to the same pH, whose reverse exchange rate (k(ws)) was found to be linearly correlated with the concentration. In summary, the proposed solution provides simplified yet reasonably accurate quantification of the underlying CEST system, which may help guide the ongoing development of quantitative CEST MRI.

  1. Effects of Exogenous Jasmonic Acid on Concentrations of Direct-Defense Chemicals and Expression of Related Genes in Bt(Bacillus thuringiensis)Corn(Zea mays)

    Institute of Scientific and Technical Information of China (English)

    FENG Yuan-jiao; WANG Jian-wu; LUO Shi-ming

    2007-01-01

    Bt corn is one of the top three large-scale commercialized transgenic crops around the world.It is increasingly clear that the complementary durable approaches for pest control,which combine the endogenous defense of the crop with the introduced foreign genes,are promising alternative strategies for pest resistance management and the next generation of insect-resistant transgenic crops.In the present study,we tested the inducible effects of exogenous jasmonic acid(JA) on direct-defense chemical content,Bt protein concentration,and related gene expression in the leaves of Bt corn cultivar 34B24 and non-Bt cultivar 34B23 by chemical analysis,ELISA,and RT-PCR.The results show that the expression of LOX,PR-2αMPI,and PR-1 genes in the treated leaf(the first leaf)was promoted by exogenous JA both in 34B24 and 34B23.As compared with the control,the concentration of DIMBOA in the treated leaf was significantly increased by 63 and 18% for 34B24 and 34B23,respectively.The total phenolic acid was also increased by 24 and 12% for both 34B24 and 34B23.The Bt protein content of 34B24 in the treated leaf was increased by 13% but decreased significantly by 27% in the second leaf.The induced response of 34B24 was in a systemic way and was much stronger than that of 34B23.Those findings indicated that there is a synergistic interaction between Bt gene and internally induced chemical defense system triggered by externally applied JA in Bt corn.

  2. Concentrations, correlations and chemical species of PM2.5/PM10 based on published data in China: Potential implications for the revised particulate standard.

    Science.gov (United States)

    Zhou, Xuehua; Cao, Zhaoyu; Ma, Yujie; Wang, Linpeng; Wu, Ruidong; Wang, Wenxing

    2016-02-01

    Particulate matter (PM) has been of great concern in China due to the increasing haze pollution in recent years. In 2012, the Chinese national ambient air quality standard (NAAQS) was amended with a "more strict" regulation on the PM concentrations, i.e., 35 and 70 µg/m(3) for annual PM2.5 and PM10 averages, respectively (Grade-Ⅱ, GB3095-2012). To evaluate the potential of China to attain such new NAAQS and provide a more generalized chemical profile of PM in China, a comprehensive statistical analysis was carried out based on the published data of parallel PM2.5 and PM10 mass concentrations and chemical compositions of PM2.5 and PM10. The results show that most of the measured concentrations far exceed the new NAAQS. PM2.5 and PM10 show a strong positive correlation (R(2) = 0.87, p China. Organic carbon (OC), sulfate and crustal species are the three major components of PM. The NO3(-)/SO4(2-) ratios are 0.43 ± 0.26 in PM2.5 and 0.56 ± 0.29 in PM10, and the OC/EC ratios are 3.63 ± 1.73 in PM2.5 and 4.17 ± 2.09 in PM10, signifying that the stationary emissions from coal combustion remain the main PM source. An evaluation of PM2.5 situation in current China was carried out and the results show that it would take about 27 years to meet the limit value of 35 µg/m(3) in the revised standard, implying a rigorous challenge in PM2.5 control in China in the future.

  3. Effect of precursor solutions stirring on deep level defects concentration and spatial distribution in low temperature aqueous chemical synthesis of zinc oxide nanorods

    Energy Technology Data Exchange (ETDEWEB)

    Alnoor, Hatim, E-mail: hatim.alnoor@liu.se; Chey, Chan Oeurn; Pozina, Galia; Willander, Magnus; Nur, Omer [Department of Science and Technology (ITN), Campus Norrköping, Linköping University, SE-601 74 Norrköping (Sweden); Liu, Xianjie; Khranovskyy, Volodymyr [Department of Physics, Chemistry and Biology (IFM), Linköping University, SE-583 81 Linköping (Sweden)

    2015-08-15

    Hexagonal c-axis oriented zinc oxide (ZnO) nanorods (NRs) with 120-300 nm diameters are synthesized via the low temperature aqueous chemical route at 80 °C on silver-coated glass substrates. The influence of varying the precursor solutions stirring durations on the concentration and spatial distributions of deep level defects in ZnO NRs is investigated. Room temperature micro-photoluminesnce (μ-PL) spectra were collected for all samples. Cathodoluminescence (CL) spectra of the as-synthesized NRs reveal a significant change in the intensity ratio of the near band edge emission (NBE) to the deep-level emission (DLE) peaks with increasing stirring durations. This is attributed to the variation in the concentration of the oxygen-deficiency with increasing stirring durations as suggested from the X-ray photoelectron spectroscopy analysis. Spatially resolved CL spectra taken along individual NRs revealed that stirring the precursor solutions for relatively short duration (1-3 h), which likely induced high super saturation under thermodynamic equilibrium during the synthesis process, is observed to favor the formation of point defects moving towards the tip of the NRs. In contrary, stirring for longer duration (5-15 h) will induce low super saturation favoring the formation of point defects located at the bottom of the NRs. These findings demonstrate that it is possible to control the concentration and spatial distribution of deep level defects in ZnO NRs by varying the stirring durations of the precursor solutions.

  4. Effect of precursor solutions stirring on deep level defects concentration and spatial distribution in low temperature aqueous chemical synthesis of zinc oxide nanorods

    Science.gov (United States)

    Alnoor, Hatim; Chey, Chan Oeurn; Pozina, Galia; Liu, Xianjie; Khranovskyy, Volodymyr; Willander, Magnus; Nur, Omer

    2015-08-01

    Hexagonal c-axis oriented zinc oxide (ZnO) nanorods (NRs) with 120-300 nm diameters are synthesized via the low temperature aqueous chemical route at 80 °C on silver-coated glass substrates. The influence of varying the precursor solutions stirring durations on the concentration and spatial distributions of deep level defects in ZnO NRs is investigated. Room temperature micro-photoluminesnce (μ-PL) spectra were collected for all samples. Cathodoluminescence (CL) spectra of the as-synthesized NRs reveal a significant change in the intensity ratio of the near band edge emission (NBE) to the deep-level emission (DLE) peaks with increasing stirring durations. This is attributed to the variation in the concentration of the oxygen-deficiency with increasing stirring durations as suggested from the X-ray photoelectron spectroscopy analysis. Spatially resolved CL spectra taken along individual NRs revealed that stirring the precursor solutions for relatively short duration (1-3 h), which likely induced high super saturation under thermodynamic equilibrium during the synthesis process, is observed to favor the formation of point defects moving towards the tip of the NRs. In contrary, stirring for longer duration (5-15 h) will induce low super saturation favoring the formation of point defects located at the bottom of the NRs. These findings demonstrate that it is possible to control the concentration and spatial distribution of deep level defects in ZnO NRs by varying the stirring durations of the precursor solutions.

  5. Effect of Annealing Temperature on the Optical Spectra of CdS Thin Films Deposited at Low Solution Concentrations by Chemical Bath Deposition (CBD Technique

    Directory of Open Access Journals (Sweden)

    Zahid Rizwan

    2011-02-01

    Full Text Available Two different concentrations of CdCl2 and (NH22CS were used to prepare CdS thin films, to be deposited on glass substrate by chemical bath deposition (CBD technique. CdCl2 (0.000312 M and 0.000625 M was employed as a source of Cd2+ while (NH22CS (0.00125 M and 0.000625 M for S2− at a constant bath temperature of 70 °C. Adhesion of the deposited films was found to be very good for all the solution concentrations of both reagents. The films were air-annealed at a temperature between 200 °C to 360 °C for one hour. The minimum thickness was observed to be 33.6 nm for film annealed at 320 °C. XRD analyses reveal that the films were cubic along with peaks of hexagonal phase for all film samples. The crystallite size of the films decreased from 41.4 nm to 7.4 nm with the increase of annealing temperature for the CdCl2 (0.000312 M. Optical energy band gap (Eg, Urbach energy (Eu and absorption coefficient (α have been calculated from the transmission spectral data. These parameters have been discussed as a function of annealing temperature and solution concentration. The best transmission (about 97% was obtained for the air-annealed films at higher temperature at CdCl2 (0.000312 M.

  6. Long repetition time experiments for measurement of concentrations in systems with chemical exchange and undergoing temporal variation-comparison of methods with and without correction for saturation

    Science.gov (United States)

    Galbán, Craig J.; Spencer, Richard G. S.

    2003-02-01

    The purpose of this paper is to compare two methods for quantifying metabolite concentrations using the one-pulse experiment for a sample undergoing chemical exchange and subject to an intervention or other temporal variation. The methods, LATR-C (Long Acquisition TR (interpulse delay); Corrected for partial saturation) and LATR-NC (Long Acquisition TR; Not Corrected), are compared in terms of signal-to-noise ratio, SNR, per unit time and quantitation errors. Parameters relevant to the isolated perfused rat heart are used as a specific application, although the results are general. We assume throughout that spin-lattice relaxation times, T1, do not change. For a given flip angle, θ, TR's are calculated which result in maximal SNR per unit time under 10%, 5%, and 1% constraints on quantitation errors. Additional simulations were performed to demonstrate explicitly the dependence of the quantitation errors on TR for a fixed θ. We find (i) if the allowed error is large, and when both metabolite concentrations and rate constants vary, LATR-C permits use of shorter TR, and hence yields greater SNR per unit time, than LATR-NC; (ii) for small allowed error, the two methods give similar TR's and SNR per unit time, so that the simpler LATR-NC experiment may be preferred; (iii) large values of θ result in similar constrained TR's and hence SNR per unit time for the two methods; (iv) the ratio of concentrations of metabolites with similar T1 exhibit similar errors for the two methods.

  7. A Greenhouse Study on Lead Uptake and Antioxidant Enzyme Activities in Vetiver Grass (Vetiveria zizanioides) as a Function of Lead Concentration and Soil Physico-Chemical Properties

    Science.gov (United States)

    Andra, S. P.; Datta, R.; Sarkar, D.; Saminathan, S. K.

    2006-05-01

    Lead (Pb) is a toxic non-essential metal that can cause permanent learning disabilities, retardation, mental and behavioral problems in children. Lead accumulation in soils result from weathering, chipping, scraping, sanding and sand blasting of housing structures constructed prior to 1978, bearing lead-based paint. The primary objective of this study is to develop a cost-effective, chelate-assisted phytoremediation for cleaning up lead contaminated soils. Soils are a unique environment of diverse physical and chemical characteristics that influence the extent of phytoavailable (labile) Pb forms. The success of phytoremediation strategy depends on the physiological/ biochemical tolerance of the plants to lipid peroxidation induced by Pb at sub-lethal levels. Oxidative challenge is alleviated by antioxidant compounds, but more importantly by the induction of antioxidant enzymes, which are crucial for scavenging reactive oxygen species (ROS) and terminating lipid peroxidation chain reaction. A column study was conducted in a temperature and humidity-controlled greenhouse setting to assess the extent of Pb phytoextraction and antioxidant response in a lead accumulator, vetiver grass (Vetiveria zizanioides). Treatments consisted of a randomized block arrangement of 4 soil types (Immokalee, Pahokee Muck, Tobosa, and Millhopper) and 3 soil Pb concentrations [normal - 400 mg/kg lead (following federal soil standards for lead), moderate - 800 mg/kg lead, and excessive - 1200 mg/kg lead] in 4 replicates. At the end of 6 months, selected columns were amended with a biodegradable chelating agent, ethylenediamene disuccinate (10 mmol/ kg EDDS), to mobilize Pb and enhance Pb uptake by vetiver. Total and exchangeable (labile) Pb were correlated with phytoextracted Pb, and levels of antioxidant enzymes viz., superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) in the root and shoot tissues of vetiver grass. Results indicate that Pb uptake and antioxidant

  8. Chemical Cleaning Analysis of Concentrated Water Reverse Osmosis Membrane%浓水反渗透膜元件化学清洗分析

    Institute of Scientific and Technical Information of China (English)

    冀美萍; 沈洪洋; 郭伟

    2011-01-01

    RO membrane fouling can cause system performance degradation, component of pressure difference between inlet and outlet, the increase of membrane components replacement. Periodic cleaning for the membrane is effective way to ensure the normal system operation and extend service life of elements of. Through analysis to the reason of concentrated reverse osmosis water system pollution, this article introduces the cleaning of reverse osmosis membrane method, and through two chemical cleaning data of dense water reverse osmosis system, it puts forward the optimal operation measures for concentrated water reverse osmosis system.%反渗透膜的污染会造成系统性能的下降、组件进出口压差的升高、膜元件的更换等。对膜进行定期的清洗是保证反渗透系统的正常运行、延长膜元件使用寿命的有效途径。通过对浓水反渗透系统污染原因的解读分析,讨论了反渗透膜清洗的方法,通过对浓水反渗透系统两次化学清洗数据进行对比分析,提出浓水反渗透系统优化运行的相关措施。

  9. Concentrations, profiles, and estimated human exposures for polychlorinated dibenzo-p-dioxins and dibenzofurans from electronic waste recycling facilities and a chemical industrial complex in Eastern China.

    Science.gov (United States)

    Ma, Jing; Kannan, Kurunthachalam; Cheng, Jinping; Horii, Yuichi; Wu, Qian; Wang, Wenhua

    2008-11-15

    Environmental pollution arising from electronic waste (e-waste) disposal and recycling has received considerable attention in recent years. Treatment, at low temperatures, of e-wastes that contain polyvinylchloride and related polymers can release polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs). Although several studies have reported trace metals and polybrominated diphenyl ethers (PBDEs) released from e-waste recycling operations, environmental contamination and human exposure to PCDD/Fs from e-waste recycling operations are less well understood. In this study, electronic shredder waste and dust from e-waste facilities, and leaves and surface soil collected in the vicinity of a large scale e-waste recycling facility in Taizhou, Eastern China, were analyzed for total PCDD/ Fs including 2,3,7,8-substituted congeners. We also determined PCDD/Fs in surface agricultural soils from several provinces in China for comparison with soils from e-waste facilities. Concentrations of total PCDD/Fs were high in all of the matrices analyzed and ranged from 30.9 to 11400 pg/g for shredder waste, 3460 to 9820 pg/g dry weight for leaves, 2560 to 148000 pg/g dry weight for workshop-floor dust, and 854 to 10200 pg/g dry weight for soils. We also analyzed surface soils from a chemical industrial complex (a coke-oven plant, a coal-fired power plant, and a chlor-alkali plant) in Shanghai. Concentrations of total PCDD/Fs in surface soil (44.5-531 pg/g dry wt) from the chemical industrial complex were lower than the concentrations found in soils from e-waste recycling plants, but higher than the concentrations found in agricultural soils. Agricultural soils from six cities in China contained low levels (3.44-33.8 pg/g dry wt) of total PCDD/Fs. Profiles of dioxin toxic equivalents (TEQs) of 2,3,7,8-PCDD/Fs in soils from e-waste facilities in Taizhou differed from the profiles found in agricultural soils. The estimated daily intakes of TEQs of PCDD/ Fs via soil/dust ingestion

  10. Effect of precursor solutions stirring on deep level defects concentration and spatial distribution in low temperature aqueous chemical synthesis of zinc oxide nanorods

    Directory of Open Access Journals (Sweden)

    Hatim Alnoor

    2015-08-01

    Full Text Available Hexagonal c-axis oriented zinc oxide (ZnO nanorods (NRs with 120-300 nm diameters are synthesized via the low temperature aqueous chemical route at 80 °C on silver-coated glass substrates. The influence of varying the precursor solutions stirring durations on the concentration and spatial distributions of deep level defects in ZnO NRs is investigated. Room temperature micro-photoluminesnce (μ-PL spectra were collected for all samples. Cathodoluminescence (CL spectra of the as-synthesized NRs reveal a significant change in the intensity ratio of the near band edge emission (NBE to the deep-level emission (DLE peaks with increasing stirring durations. This is attributed to the variation in the concentration of the oxygen-deficiency with increasing stirring durations as suggested from the X-ray photoelectron spectroscopy analysis. Spatially resolved CL spectra taken along individual NRs revealed that stirring the precursor solutions for relatively short duration (1-3 h, which likely induced high super saturation under thermodynamic equilibrium during the synthesis process, is observed to favor the formation of point defects moving towards the tip of the NRs. In contrary, stirring for longer duration (5-15 h will induce low super saturation favoring the formation of point defects located at the bottom of the NRs. These findings demonstrate that it is possible to control the concentration and spatial distribution of deep level defects in ZnO NRs by varying the stirring durations of the precursor solutions.

  11. Effect of annealing temperature on the optical spectra of CdS thin films deposited at low solution concentrations by Chemical Bath Deposition (CBD) Technique.

    Science.gov (United States)

    Rizwan, Zahid; Zakaria, Azmi; Mohd Ghazali, Mohd Sabri; Jafari, Atefeh; Din, Fasih Ud; Zamiri, Reza

    2011-02-22

    Two different concentrations of CdCl(2) and (NH(2))(2)CS were used to prepare CdS thin films, to be deposited on glass substrate by chemical bath deposition (CBD) technique. CdCl(2) (0.000312 M and 0.000625 M) was employed as a source of Cd(2+) while (NH(2))(2)CS (0.00125 M and 0.000625 M) for S(2-) at a constant bath temperature of 70 °C. Adhesion of the deposited films was found to be very good for all the solution concentrations of both reagents. The films were air-annealed at a temperature between 200 °C to 360 °C for one hour. The minimum thickness was observed to be 33.6 nm for film annealed at 320 °C. XRD analyses reveal that the films were cubic along with peaks of hexagonal phase for all film samples. The crystallite size of the films decreased from 41.4 nm to 7.4 nm with the increase of annealing temperature for the CdCl(2) (0.000312 M). Optical energy band gap (E(g)), Urbach energy (E(u)) and absorption coefficient (α) have been calculated from the transmission spectral data. These parameters have been discussed as a function of annealing temperature and solution concentration. The best transmission (about 97%) was obtained for the air-annealed films at higher temperature at CdCl(2) (0.000312 M).

  12. Application of WRF/Chem-MADRID and WRF/Polyphemus in Europe – Part 2: Evaluation of chemical concentrations, sensitivity simulations, and aerosol-meteorology interactions

    Directory of Open Access Journals (Sweden)

    C. Seigneur

    2013-02-01

    better the observations of PM10 concentrations at all sites. The differences between model predictions and observations are mostly caused by inaccurate representations of emissions of gaseous precursors and primary PM species, as well as biases in the meteorological predictions. The differences in model predictions are caused by differences in the heights of the first model layers and thickness of each layer that affect vertical distributions of emissions, model treatments such as dry/wet deposition, heterogeneous chemistry, and aerosol and cloud, as well as model inputs such as emissions of soil dust and sea-salt and chemical boundary conditions of CO and O3 used in both models. WRF/Chem-MADRID shows a higher sensitivity to grid resolution than WRF/Polyphemus at all sites. For both models, the use of a finer grid resolution generally leads to an overall better statistical performance for most variables, with greater spatial details and an overall better agreement in temporal variations and magnitudes at most sites. The use of online BVOC emissions gives better statistical performance for hourly and max 8-h O3 and PM2.5 and generally better agreement with their observed temporal variations at most sites. Because it is an online model, WRF/Chem-MADRID offers the advantage to account for various feedbacks between meteorology and chemical species. The simulations show that aerosol leads to reduced net shortwave radiation fluxes, 2-m temperature, 10-m wind speed, PBL height, and precipitation and increases aerosol optical depth, cloud condensation nuclei, cloud optical depth, and cloud droplet number concentrations over most of the domain. However, this model comparison suggests that atmospheric pollutant concentrations are most sensitive in state-of-the-science air quality models to vertical structure, inputs, and parameterizations for dry/wet removal of gases and particles in the model.

  13. High concentrations of N2O5 and NO3 observed in daytime with a TD-CIMS: chemical interference or a real atmospheric phenomenon?

    Directory of Open Access Journals (Sweden)

    X. Wang

    2013-08-01

    Full Text Available Dinitrogen pentoxide (N2O5 and the nitrate radical (NO3 play important roles in atmospheric chemistry, yet accurate measurements of their concentrations remain challenging. A thermal dissociation chemical ionization mass spectrometer (TD-CIMS was deployed to an urban site in Hong Kong to measure the sum of N2O5 and NO3 in autumn 2010. To our surprise, very high concentrations of N2O5 + NO3 were frequently observed in daytime, with mixing ratios in the range of 200–1000 pptv. To investigate this unusual phenomenon, various interference tests and measurements with different instrument configuration were conducted. It was found that peroxy acetyl nitrate (PAN contributed to measurable signals at 62 amu, and more importantly, this interference increased significantly with co-existence of NO2. Nitric acid (HNO3, on the other hand, had little interference to the detection of N2O5/NO3 via the NO3− ion in our TD-CIMS. According to the test results, the interference from PAN and NO2 could have contributed to 30–50% of the average daytime (12:00–16:00 LT N2O5 + NO3 signal at our site. However, evidence exists for the presence of elevated daytime N2O5, in addition to the daytime signal at 62 amu. This includes: (1 daytime N2O5 measured via the I(N2O5− cluster ion with an unheated inlet, which subjects to minimum interferences, and (2 observation of elevated daytime ClNO2 (a product of N2O5 hydrolysis during a follow-up study. In view of the difficulty in accurately quantifying the contribution from the interferences of PAN and NO2 and un-tested potential interfering chemicals in the real atmosphere, we caution the use of 62 amu in the TD-CIMS for measuring ambient N2O5 in a high NOx environment like Hong Kong. Additional studies are needed to re-examine the daytime issue using other measurement techniques.

  14. Achieving low effluent NO3-N and TN concentrations in low influent chemical oxygen demand (COD) to total Kjeldahl nitrogen (TKN) ratio without using external carbon source

    Science.gov (United States)

    Cao, Jiashun; Oleyiblo, Oloche James; Xue, Zhaoxia; Otache, Y. Martins; Feng, Qian

    2015-07-01

    Two mathematical models were used to optimize the performance of a full-scale biological nutrient removal (BNR) activated treatment plant, a plug-flow bioreactors operated in a 3-stage phoredox process configuration, anaerobic anoxic oxic (A2/O). The ASM2d implemented on the platform of WEST2011 software and the BioWin activated sludge/anaerobic digestion (AS/AD) models were used in this study with the aim of consistently achieving the designed effluent criteria at a low operational cost. Four ASM2d parameters (the reduction factor for denitrification , the maximum growth rate of heterotrophs (µH), the rate constant for stored polyphosphates in PAOs ( q pp), and the hydrolysis rate constant ( k h)) were adjusted. Whereas three BioWin parameters (aerobic decay rate ( b H), heterotrophic dissolved oxygen (DO) half saturation ( K OA), and Y P/acetic) were adjusted. Calibration of the two models was successful; both models have average relative deviations (ARD) less than 10% for all the output variables. Low effluent concentrations of nitrate nitrogen (N-NO3), total nitrogen (TN), and total phosphorus (TP) were achieved in a full-scale BNR treatment plant having low influent chemical oxygen demand (COD) to total Kjeldahl nitrogen (TKN) ratio (COD/TKN). The effluent total nitrogen and nitrate nitrogen concentrations were improved by 50% and energy consumption was reduced by approximately 25%, which was accomplished by converting the two-pass aerobic compartment of the plug-flow bioreactor to anoxic reactors and being operated in an alternating mode. Findings in this work are helpful in improving the operation of wastewater treatment plant while eliminating the cost of external carbon source and reducing energy consumption.

  15. Fate models for chemical substances in exposure and risk assessment. Focused on estimation of atmospheric concentration; Bakuro{center_dot}risuku hyoka ni okeru kagaku busshitsu unmei yosoku moderu. Taikichu nodo suitei wo chushin toshite

    Energy Technology Data Exchange (ETDEWEB)

    Higashino, H. [National Inst. for Resources and Environment, Tsukuba (Japan)

    2000-09-20

    A fate model is one of the most effective tools in exposure and risk assessment of chemical substances. Two different type models are available for estimating the atmospheric concentration. One is unit box and multi compartment type model, the other is atmospheric dispersion model. These models should be used in different suitable situations because each model has both advantage and disadvantage. Estimation of the long-term average concentration in a comparatively wide region into which substances are continuously discharged should be required in the environmental assessment of chemical substances. We developed the model with which to estimate long-term average atmospheric concentrations of chemicals. The model validation was conducted for trichloroethylene and tetrachloroethylene concentrations in the atmosphere by comparing calculated values and observed values. Good agreement with the measured values was obtained for the monthly average concentration. The model is capable of estimating the long-term (such as monthly) average distribution of concentration of chemicals in a wide flat area such as the Kanto plain. (author)

  16. ANALYSIS OF DEPENDENCE OF THE FLOW TEMPERATURE OF THE PLASTICIZED POLYMER ON THE CHEMICAL STRUCTURE AND CONCENTRATION OF THE POLYMER AND THE PLASTICIZER

    Directory of Open Access Journals (Sweden)

    Askadskiy Andrey Aleksandrovich

    2012-10-01

    Full Text Available Polymeric materials are widely used in construction. The properties of polymeric construction materials vary to a substantial extent; their durability, thermal stability, frost resistance, waterproof and dielectric properties are particularly pronounced. Their properties serve as the drivers of the high market demand for these products. These materials are applied as finishing materials, molded sanitary engineering products and effective thermal insulation and water proofing materials. The authors analyze the influence of the chemical structure and structural features of polymers on their properties. The authors consider flow and vitrification temperatures of polymers. These temperatures determine the parameters of polymeric products, including those important for the construction process. The analysis of influence of concentration of the plasticizer on the vitrification temperature is based on the two basic theories. In accordance with the first one, reduction of the vitrification temperature is proportionate to the molar fraction of the injected plasticizer. According to the second concept, reduction of the vitrification temperature is proportionate to the volume fraction of the injected solvent. Dependencies of the flow temperature on the molecular weight and the molar fraction of the plasticizer are derived for PVC. As an example, two plasticizers were considered, including dibutyl sebacate and dioctylftalatalate. The basic parameters of all mixtures were calculated through the employment of "Cascade" software programme (A.N. Nesmeyanov Institute of Organoelemental Connections, Russian Academy of Sciences.

  17. Seasonal and spatial variation of trace elements in multi-size airborne particulate matters of Beijing, China: Mass concentration, enrichment characteristics, source apportionment, chemical speciation and bioavailability

    Science.gov (United States)

    Gao, Jiajia; Tian, Hezhong; Cheng, Ke; Lu, Long; Wang, Yuxuan; Wu, Ye; Zhu, Chuanyong; Liu, Kaiyun; Zhou, Junrui; Liu, Xingang; Chen, Jing; Hao, Jiming

    2014-12-01

    The seasonal and spatial variation characteristics of 19 elements (Al, As, Be, Ca, Cd, Co, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, Pb, S, Sb, Se, Zn) in TSP/PM10/PM2.5 samples were investigated, which were collected from April 2011 to January 2012 simultaneously at an urban downtown site, a traffic roadside site, a suburban site, and a rural site in Beijing. The elevated concentrations of several toxic trace elements (As, Cd, Mn, Ni, Pb, etc.) in particles revealed that the contamination of toxic elements in Beijing could not be neglected. Positive matrix factorization method (PMF) was applied for source apportionment of trace elements in PM, and three factors (crust related sources, combustion sources, and traffic and steel industrial related sources) were identified. Furthermore, the chemical speciation and bioavailability of various elements were identified by applying European Community Bureau of Reference (BCR) procedure. Our results showed that eight toxic elements (As, Cd, Cr, Cu, Ni, Pb, Sb and Zn) exhibited higher mobility in PM2.5 than in PM10. Notably, elements of As, Cd, Pb and Zn were presented with higher mobility than the other elements, and these elements were lightly to release into the environment and easily available to human body. Additionally, As, Cd, Pb and Zn also accounted for higher percentages in the bound to mobile fractions at the central urban areas of Beijing. Therefore, special concerns should be paid to these toxic trace elements which had relatively high mobility in fine particles, when planning and implementing the comprehensive air pollution mitigation policies in Beijing.

  18. Chemical sensors

    Science.gov (United States)

    Lowell, J.R. Jr.; Edlund, D.J.; Friesen, D.T.; Rayfield, G.W.

    1991-07-02

    Sensors responsive to small changes in the concentration of chemical species are disclosed. The sensors comprise a mechanochemically responsive polymeric film capable of expansion or contraction in response to a change in its chemical environment. They are operatively coupled to a transducer capable of directly converting the expansion or contraction to a measurable electrical response. 9 figures.

  19. Microfluidic chemical reaction circuits

    Science.gov (United States)

    Lee, Chung-cheng; Sui, Guodong; Elizarov, Arkadij; Kolb, Hartmuth C.; Huang, Jiang; Heath, James R.; Phelps, Michael E.; Quake, Stephen R.; Tseng, Hsian-rong; Wyatt, Paul; Daridon, Antoine

    2012-06-26

    New microfluidic devices, useful for carrying out chemical reactions, are provided. The devices are adapted for on-chip solvent exchange, chemical processes requiring multiple chemical reactions, and rapid concentration of reagents.

  20. Electronic tongue response to chemicals in orange juice that change concentration in relation to harvest maturity and citrus greening or Huanglongbing (HLB) disease

    Science.gov (United States)

    In an earlier study, the electronic tongue system (etongue) was used to differentiate between orange juice made from healthy fruit and from fruit affected by the citrus greening or Huanglongbing (HLB) disease. This study investigated the reaction of an etongue system to the main chemicals in orange ...

  1. Influence of ethanol concentration, addition of spices extract, and level of sweetness on physico-chemical characteristics and sensory quality of apple vermouth

    Directory of Open Access Journals (Sweden)

    Vinod K. Joshi

    2000-01-01

    Full Text Available The composition of apple base wine was found to be suitable for conversion into vermouth. The spices extract contained more TSS, tannins, esters, volatile acid but lower titrable acid than apple base wine. To optimize and develop apple vermouth with different ethanol concentrations (12%, 15%, 18%, sugar content (4%, 8% and spices extract (2.5% and 5.0% was prepared and was evaluated. Significant differences in physico-chemical characteristics and sensory quality amongst the vermouths having different levels of alcohol, sugar and spices extract were noted. Generally, increasing ethanol content decreased titrable acidity, tannins, macroelements and colour units while micro-elements, viscosity and total esters were increased. Increased sugar level affected TSS, apparent viscosity, pH, esters, free aldehyde, total sugar, K, Cu and Mn contents. Level of spices extract (2.5 & 5.0 did not effect TSS (ºB, titrable acidity, colour, total sugar, total tannins, volatile acidity, increased mineral contents except for K, esters and aldehyde contents. Increase in alcohol content upto 15% increased the sensory score of the product. Increased quantity of spices extract, however, decreased the mean sensory quality of vermouth. However, sensory scores for 4 or 8% sugar and 2.5 or, 5.0% spices extracted were similar. A product with 15% alcohol, 4% sugar and 2.5% spices extract was preferred the most in overall sensory quality. The studies revealed that apple fruit is suitable for making vermouth by the method described. The spices, herbs, their parts and the quantities used are also reported.A composição de vinho de maçã demonstrou ser satisfatório para se convertido em vermute. O extrato de especiarias apresentou mais TSS, taninos, esters, porém os ácido volátil titulaveis foi mais baixo que no vinho de maçã. Estudos foram realizados para aperfeiçoar e desenvolver vermute de maçã contendo diferentes concentrações de ethanol (12%, 15%, 18%, de a

  2. Experimental investigation on moving chemical reaction boundary theory for weak-acid-strong-base system with background electrolyte KCl in large concentration.

    Science.gov (United States)

    Cao, C X; Zhou, S L; Qian, Y A; He, Y Z; Yang, L; Qu, Q S; Chen, W K

    2001-07-13

    In this report, the moving chemical reaction boundary (MCRB) was formed with the weak acid of acetic acid (HAc) and the strong alkali of NaOH, coupled with the excess of background electrolyte KCl. The experiments were compared with the predictions by the moving chemical reaction boundary equation (MCRBE). It is very interesting that (1) the experimental results are in good agreement with the predictions with the original MCRBE if the MCRB is an anodic moving boundary, (2) however, the experiments are extremely far away from the predictions with the original MCRBE if a cathodic moving boundary. Hence, the original MCRBE must be corrected under the later situation of cathodic moving MCRB. The corrected MCRBE was well quantitatively proved to be valid for the cathodic moving MNRB formed with the same electrolytes of HAc, NaOH and KCl.

  3. Determination of concentration of occupational chemical hazards of a synthetic rubber factory%某合成橡胶厂化学有害因素浓度测定分析

    Institute of Scientific and Technical Information of China (English)

    韩小红; 杨雷波; 董瑞风

    2012-01-01

    目的 分析、掌握某合成橡胶生产企业作业场所中化学有害因素的浓度变化.方法 对其存在的职业病危害化学有害因素连续2年进行检测检验.结果 某合成橡胶厂主要职业病危害化学有害因素为氨、氯气、氯丁二烯、甲苯、盐酸、硫酸、硫化氢、磷化氢、乙醛、乙酸、氢氧化钠、碳酸钠等.其中氨、氯气、硫化氢、磷化氢为高毒物品,但工作场所中浓度检测均未超限,氯丁二烯、乙酸等虽属一般化学有害物质,但检测点有超标样本,职业危害程度分别为中度和轻度危害.结论 企业应落实改进建议,使作业场所职业病危害化学有害因素的浓度符合国家标准,以保护劳动者的健康.%[Objective]To analyze and explore the concentration variation of occupational chemical hazards in die workplace of a synthectic rubber factory. [ Methods] The concentration of occupational chemical hazards in this factory was detected for continuously 2 years. [ Results] The major occupational chemical hazards were ammonia, chlorine, chlorine butadiene , toluene , hydrochloric acid , sulfuric acid , hydrogen sulfide , phosphine , acetaldehyde , acetic acid , sodium hydroxide , sodium carbonate and so on, including hypertoxic chemicals of ammonia , chlorine , hydrogen sulfide, phosphine whose concentrations did not exceed limits.. Although chlorine butadiene, acetic acid and others were normal chemical poisons, some samples exceeded standards with moderate and mild harm according to occupational hazards classification. [Conclusion]This factory should cany out the improved suggestion to make the concentration of occupational chemical hazards in the workplace correspond with national standard and protect the health of workers.

  4. Effect of Catchment Area Activities on the Physico – Chemical Characteristics of Water of Upper Lake, Bhopal with Special Reference to Nitrate and Phosphate Concentration

    Directory of Open Access Journals (Sweden)

    Ranjana Talwar

    2014-04-01

    Full Text Available With the tremendous influx of people and consequent urban development, increased anthropogenic activities in the catchment, inflow of untreated sewage, nutrients and pesticides from urban and rural areas, the water quality of Upper Lake, Bhopal has deteriorated significantly. An attempt has been made to study various physico – chemical parameters, specifically nitrates and phosphates of five different sampling sites of Upper Lake and to study the effect of catchment area activities on these sites.

  5. Thorotrast: analysis of the time evolution of its α activity concentration, in the 70 years following the chemical purification of Thorium.

    Science.gov (United States)

    Bianconi, A; Corradini, M; Leali, M; Lodi Rizzini, E; Venturelli, L; Zurlo, N

    2013-09-01

    We simulate the α-activity of the Thorium series elements present in the contrast medium named Thorotrast, used until 1960 and cause of certified deaths until today. Assuming, as active components at t=0, (232)Th and (228)Th in the same relative concentration they have in nature, α-activity oscillates for some decades before reaching a stationary value that in absence of biological depletion would be AST =24000Bq/g. Our Montecarlo code generates the nuclear decays of the Thorium series with and without in-vivo biological depletion, arriving to three kinds of results for the activity: 1) Theoretical activity concentration (no biological depletion). Our result is fitted by: A(t)=A(ST).{[1-exp(-t/10)]+[exp(-t/tB)(1-0.8exp(-t/tA))]}, with t in years, tA=1.07.10(-2) years, and tB=2.38 years. 2) Weak biological depletion (228Ra/232 Th equilibrium activity ratio 0.6, 224Ra/228Ra e.a.r 0.9, 10% excretion for 220Rn). The ratio of the activity concentration to the theoretical activity concentration is fitted by: A weak (t)/A(t)=0.61+0.29 exp[-(t/15)2] (t in years). 3) Strong biological depletion (228Ra/232Th e.a.r 0.4, 224Ra/228Ra e.a.r. 0.8, 10% excretion for 220Rn). The ratio of the activity concentration to the theoretical activity concentration is fitted by A(strong)(t)/A(t)=0.44+0.4 exp[-(t/13)2](t in years). We also report fluctuation calculation for two cases where standard statistical behavior is not expected.

  6. Effects of elevated atmospheric CO2 concentration and increased nitrogen deposition on growth and chemical composition of ombrotrophic Sphagnum balticum and oligo-mesotrophic Sphagnum papillosum

    NARCIS (Netherlands)

    Van der Heijden, E; Jauhiainen, J; Silvola, J; Vasander, H; Kuiper, PJC

    2000-01-01

    The ombrotrophic Sphagnum balticum (Russ.) C. Jens. and the oligo-mesotrophic Sphagnum papillosum Lindb. were grown at ambient (360 mu l l(-1)) and at elevated (720 mu l l(-1)) atmospheric CO2 concentrations and at different nitrogen deposition rates, varying between 0 and 30kg N ha(-1) yr(-1), The

  7. Non-refractory PM1 in SE Asia: Chemically speciated aerosol fluxes and concentrations above contrasting land-uses in SE Asia.

    Science.gov (United States)

    Phillips, Gavin; Farmer, Delphine; di Marco, Chiara; Misztal, Pawel; Sueper, Donna; Kimmel, Joel; Jimenez, Jose; Fowler, David; Nemitz, Eiko

    2010-05-01

    New measurements of VOC emissions (measured with leaf cuvettes, and ecosystem fluxes obtained from eddy covariance measurements) suggest that oil palm (Elaeis guineensis Jacq) is a significantly larger source of isoprene than tropical forest, in Borneo. These larger sources of isoprene measured over oil palm, allied with a larger anthropogenic component of local emissions, contrasts with the composition of the atmosphere in the semi-remote tropical forest environment. The difference in the atmospheric composition above different land-uses has the potential to lead to contrasting chemistry and physics controlling the formation and processing of particulate matter. Thus land use changes, driven by the economics of biofuels, could give rise to rapidly changing chemical and aerosol regimes in the tropics. It is therefore important to understand the current emissions, chemical processing and composition of organic aerosol over both (semi-)natural and anthropogenic land uses in the tropical environment. Ecosystem flux measurements of chemically-speciated non-refractory PM1 were made over two contrasting land uses in the Malaysian state of Sabah, on the island of Borneo during 2008. A high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) was deployed at the Global Atmospheric Watch (GAW) site at a tropical rain forest location as well as the Sabahmas (PPB OIL) oil palm plantation near Lahad Datu, in Eastern Sabah, as a collaboration between three UK NERC funded projects (OP3, APPRAISE/ACES and DIASPORA). Recent technical developments using ToF detectors allow us to record 10 Hz full mass spectra at both high resolution (HR) and unit-mass resolution (UMR), suitable for the calculation of local eddy-covariance fluxes. The measurements provide information on the deposition rate of anthropogenic aerosol components (e.g. sulphate, nitrate, ammonium and hydrocarbon-like aerosol) to tropical forest and oil palm. At the same time, any biogenic secondary organic

  8. Chemical Concentrations in Field Mice from Open-Detonation Firing Sites TA-36 Minie and TA-39 Point 6 at Los Alamos National Laboratory

    Energy Technology Data Exchange (ETDEWEB)

    Fresquez, Philip R. [Los Alamos National Laboratory

    2011-01-01

    Field mice (mostly Peromyscus spp.) were collected at two open-detonation (high explosive) firing sites - Minie at Technical Area (TA) 36 and Point 6 at TA-39 - at Los Alamos National Laboratory in August of 2010 and in February of 2011 for chemical analysis. Samples of whole body field mice from both sites were analyzed for target analyte list elements (mostly metals), dioxin/furans, polychlorinated biphenyl congeners, high explosives, and perchlorate. In addition, uranium isotopes were analyzed in a composite sample collected from TA-36 Minie. In general, all constituents, with the exception of lead at TA-39 Point 6, in whole body field mice samples collected from these two open-detonation firing sites were either not detected or they were detected below regional statistical reference levels (99% confidence level), biota dose screening levels, and/or soil ecological chemical screening levels. The amount of lead in field mice tissue collected from TA-39 Point 6 was higher than regional background, and some lead levels in the soil were higher than the ecological screening level for the field mouse; however, these levels are not expected to affect the viability of the populations over the site as a whole.

  9. Vertical transport rates and concentrations of OH and Cl radicals in the Tropical Tropopause Layer from observations of CO2 and halocarbons: implications for distributions of long- and short-lived chemical species

    Directory of Open Access Journals (Sweden)

    T. P. Bui

    2010-07-01

    Full Text Available Rates for large-scale vertical transport of air in the Tropical Tropopause Layer (TTL were determined using high-resolution, in situ observations of CO2 concentrations in the tropical upper troposphere and lower stratosphere during the NASA Tropical Composition, Cloud and Climate Coupling (TC4 campaign in August 2007. Upward movement of trace gases in the deep tropics was notably slower in TC4 than during the Costa Rica AURA Validation Experiment (CR-AVE, in January 2006. Transport rates in the TTL were combined with in situ measurements of chlorinated and brominated organic compounds from whole air samples to determine chemical loss rates for reactive chemical species, providing empirical vertical profiles for 24-h mean concentrations of hydroxyl radicals (OH and chlorine atoms in the TTL. The analysis shows that important short-lived species such as CHCl3, CH2Cl2, and CH2Br2 have longer chemical lifetimes than the time for transit of the TTL, implying that these species, which are not included in most models, could readily reach the stratosphere and make significant contributions of chlorine and/or bromine to stratospheric loading.

  10. Vertical transport rates and concentrations of OH and Cl radicals in the Tropical Tropopause Layer from Observations of CO2 and halocarbons: implications for distributions of long- and short-lived chemical species

    Directory of Open Access Journals (Sweden)

    T. P. Bui

    2010-03-01

    Full Text Available Rates for large-scale vertical transport of air in the Tropical Tropopause Layer (TTL were determined using high-resolution, in situ observations of CO2 concentrations in the tropical upper troposphere and lower stratosphere during the NASA Tropical Composition, Cloud and Climate Coupling (TC4 campaign in August 2007. Upward movement of trace gases in the deep tropics was notably slower in TC4 than during the Costa Rica AURA Validation Experiment (CR-AVE, in January 2006. Transport rates in the TTL were combined with in situ measurements of chlorinated and brominated organic compounds from whole air samples to determine chemical loss rates for reactive chemical species, providing empirical vertical profiles for 24-h mean concentrations of hydroxyl radicals (OH and chlorine atoms in the TTL. The analysis shows that important short-lived species such as CHCl3, CH2Cl2, and CH2Br2 have longer chemical lifetimes than the time for transit of the TTL, implying that these species, which are not included in most models, could readily reach the stratosphere and make significant contributions of chlorine and/or bromine to stratospheric loading.

  11. A method for the concentration of fine-grained rutile (TiO2) from sediment and sedimentary rocks by chemical leaching

    Science.gov (United States)

    Commeau, Judith A.; Valentine, Page C.

    1991-01-01

    Quaternary marine sediment in the Gulf of Maine basins contains 0.7 to 1.0 wt percent TiO2 (determined by X-ray fluorescence spectrometry). Most of this TiO2 exists in the form of silt-size rutile crystals that are visible by using the petrographic microscope with transmitted light (Valentine and Commeau, 1990). The identification of rutile was confirmed by using a scanning electron microscope (SEM) equipped with an energy-dispersive X-ray spectrometer (EDS) system. To quantify the amount of TiO2 in the sediment contributed by rutile and its polymorphs, anatase and brookite, it was necessary to eliminate as many of the other minerals as possible, especially titanium-bearing minerals such as ilmenite, ilmenomagnetite, biotite, hornblende, oyroxene, and sphene. We accomplished this by developing a method of chemical dissolution that removed the bulk of the raw material and left the TiO2 minerals intact.

  12. Chemical and Sensory Quantification of Geosmin and 2-Methylisoborneol in Rainbow Trout (Oncorhynchus mykiss) from Recirculated Aquacultures in Relation to Concentrations in Basin Water

    DEFF Research Database (Denmark)

    Petersen, Mikael A.; Hyldig, Grethe; Strobel, Bjarne W.;

    2011-01-01

    Globally, aquaculture systems with water recirculation experience increasing problems with microbial taste and odor compounds (TOCs) such as geosmin and 2-methylisoborneol (MIB). This study investigated the content of geosmin and MIB in water and the flesh of 200 rainbow trouts from eight...... recirculated aquaculture systems in Denmark. TOC content in the fish flesh was measured by a dynamic headspace extraction method and was evaluated by a sensory panel. The results showed significant correlations between TOC content in water and fish and between chemical analysis and sensory perception. When...... geosmin exceeded 20 ng/L in the water, 96% of the fish had an intense muddy flavor, but below 10 ng geosmin/L, 18% of the fish (only 3% in special depuration ponds) had an intense muddy flavor. The results indicate that TOC levels...

  13. Chemical and sensory quantification of geosmin and 2-methylisoborneol in rainbow trout (Oncorhynchus mykiss) from recirculated aquacultures in relation to concentrations in basin water.

    Science.gov (United States)

    Petersen, Mikael A; Hyldig, Grethe; Strobel, Bjarne W; Henriksen, Niels H; Jørgensen, Niels O G

    2011-12-14

    Globally, aquaculture systems with water recirculation experience increasing problems with microbial taste and odor compounds (TOCs) such as geosmin and 2-methylisoborneol (MIB). This study investigated the content of geosmin and MIB in water and the flesh of 200 rainbow trouts from eight recirculated aquaculture systems in Denmark. TOC content in the fish flesh was measured by a dynamic headspace extraction method and was evaluated by a sensory panel. The results showed significant correlations between TOC content in water and fish and between chemical analysis and sensory perception. When geosmin exceeded 20 ng/L in the water, 96% of the fish had an intense muddy flavor, but below 10 ng geosmin/L, 18% of the fish (only 3% in special depuration ponds) had an intense muddy flavor. The results indicate that TOC levels <10 ng/L will ensure that a negligible portion of the fish obtains an unpalatable taste and flavor due to TOCs.

  14. Fungal endophytes of Alpinia officinarum rhizomes: insights on diversity and variation across growth years, growth sites, and the inner active chemical concentration.

    Science.gov (United States)

    Shubin, Li; Juan, Huang; RenChao, Zhou; ShiRu, Xu; YuanXiao, Jin

    2014-01-01

    In the present study, the terminal-restriction fragment length polymorphism (T-RFLP) technique, combined with the use of a clone library, was applied to assess the baseline diversity of fungal endophyte communities associated with rhizomes of Alpinia officinarum Hance, a medicinal plant with a long history of use. A total of 46 distinct T-RFLP fragment peaks were detected using HhaI or MspI mono-digestion-targeted, amplified fungal rDNA ITS sequences from A. officinarum rhizomes. Cloning and sequencing of representative sequences resulted in the detection of members of 10 fungal genera: Pestalotiopsis, Sebacina, Penicillium, Marasmius, Fusarium, Exserohilum, Mycoleptodiscus, Colletotrichum, Meyerozyma, and Scopulariopsis. The T-RFLP profiles revealed an influence of growth year of the host plant on fungal endophyte communities in rhizomes of this plant species; whereas, the geographic location where A. officinarum was grown contributed to only limited variation in the fungal endophyte communities of the host tissue. Furthermore, non-metric multidimensional scaling (NMDS) analysis across all of the rhizome samples showed that the fungal endophyte community assemblages in the rhizome samples could be grouped according to the presence of two types of active indicator chemicals: total volatile oils and galangin. Our present results, for the first time, address a diverse fungal endophyte community is able to internally colonize the rhizome tissue of A. officinarum. The diversity of the fungal endophytes found in the A. officinarum rhizome appeared to be closely correlated with the accumulation of active chemicals in the host plant tissue. The present study also provides the first systematic overview of the fungal endophyte communities in plant rhizome tissue using a culture-independent method.

  15. Uncertainty in the uptake coefficient for HONO formation on soot and its impacts on concentrations of major chemical components in the Beijing-Tianjin-Hebei region

    Science.gov (United States)

    Tang, Y.; An, J.; Li, Y.; Wang, F.

    2014-12-01

    The soot redox reaction with an uptake coefficient (γ) of 10-4 at night and the soot heterogeneous photochemistry with the γ formula of JNO2/10 in the daytime, where JNO2 denotes the NO2 photolysis frequency, were inserted into the WRF-Chem model to evaluate the effects of γ changes of several orders of magnitude on the concentrations of HONO, HOx, O3, NO3-, and NH4+ in the Beijing-Tianjin-Hebei (BTH) region. Results demonstrated that the simulations in the BTH region support the redox mechanism at night and the heterogeneous photochemistry mechanism in the daytime for HONO formation, and suggested that the order of magnitude of γ is likely to be 10-4. Minor increases in HONO, HOx, O3, NO3-, and NH4+ were produced when γ was decreased to ≤ 10-5, whereas the concentrations of HONO and NO3- were substantially overestimated in most cases when γ was increased to 10-3. The soot surface area per unit volume of air showed a sharp decrease from 3×103 μm2 cm-3 near the ground to 6×102 μm2 cm-3 at ~200 m at night. The surface area fractions of soot, nitrate, and sulfate showed minor variations between day and night, although the surface areas of the major aerosol components at night were ~ three times those in the daytime.

  16. Interactions of Zn(II) Ions with Humic Acids Isolated from Various Type of Soils. Effect of pH, Zn Concentrations and Humic Acids Chemical Properties.

    Science.gov (United States)

    Boguta, Patrycja; Sokołowska, Zofia

    2016-01-01

    The main aim of this study was the analysis of the interaction between humic acids (HAs) from different soils and Zn(II) ions at wide concentration ranges and at two different pHs, 5 and 7, by using fluorescence and FTIR spectroscopy, as well as potentiometric measurements. The presence of a few areas of HAs structures responsible for Zn(II) complexing was revealed. Complexation at α-sites (low humified structures of low-molecular weight and aromatic polycondensation) and β-sites (weakly humified structures) was stronger at pH 7 than 5. This trend was not observed for γ-sites (structures with linearly-condensed aromatic rings, unsaturated bonds and large molecular weight). The amount of metal complexed at pH5 and 7 by α and γ-structures increased with a decrease in humification and aromaticity of HAs, contrary to β-areas where complexation increased with increasing content of carboxylic groups. The stability of complexes was higher at pH 7 and was the highest for γ-structures. At pH 5, stability decreased with C/N increase for α-areas and -COOH content increase for β-sites; stability increased with humification decrease for γ-structures. The stability of complexes at α and β-areas at pH 7 decreased with a drop in HAs humification. FTIR spectra at pH 5 revealed that the most-humified HAs tended to cause bidentate bridging coordination, while in the case of the least-humified HAs, Zn caused bidentate bridging coordination at low Zn additions and bidentate chelation at the highest Zn concentrations. Low Zn doses at pH 7 caused formation of unidentate complexes while higher Zn doses caused bidentate bridging. Such processes were noticed for HAs characterized by high oxidation degree and high oxygen functional group content; where these were low, HAs displayed bidentate bridging or even bidentate chelation. To summarize, the above studies have showed significant impact of Zn concentration, pH and some properties of HAs on complexation reactions of humic

  17. Electronic Tongue Response to Chemicals in Orange Juice that Change Concentration in Relation to Harvest Maturity and Citrus Greening or Huanglongbing (HLB) Disease.

    Science.gov (United States)

    Raithore, Smita; Bai, Jinhe; Plotto, Anne; Manthey, John; Irey, Mike; Baldwin, Elizabeth

    2015-12-02

    In an earlier study, an electronic tongue system (e-tongue) has been used to differentiate between orange juice made from healthy fruit and from fruit affected by the citrus greening or Huanglongbing (HLB) disease. This study investigated the reaction of an e-tongue system to the main chemicals in orange juice that impact flavor and health benefits and are also impacted by HLB. Orange juice was spiked with sucrose (0.2-5.0 g/100 mL), citric acid (0.1%-3.0% g/100 mL) and potassium chloride (0.1-3.0 g/100 mL) as well as the secondary metabolites nomilin (1-30 µg/mL), limonin (1-30 µg/mL), limonin glucoside (30-200 µg/mL), hesperidin (30-400 µg/mL) and hesperetin (30-400 µg/mL). Performance of Alpha MOS sensor sets #1 (pharmaceutical) and #5 (food) were compared for the same samples, with sensor set #1 generally giving better separation than sensor set #5 for sucrose, sensor set #5 giving better separation for nomilin and limonin, both sets being efficient at separating citric acid, potassium chloride, hesperitin and limonin glucoside, and neither set discriminating hesperidin efficiently. Orange juice made from fruit over the harvest season and from fruit harvested from healthy or HLB-affected trees were separated by harvest maturity, disease state and disease severity.

  18. Electronic Tongue Response to Chemicals in Orange Juice that Change Concentration in Relation to Harvest Maturity and Citrus Greening or Huanglongbing (HLB Disease

    Directory of Open Access Journals (Sweden)

    Smita Raithore

    2015-12-01

    Full Text Available In an earlier study, an electronic tongue system (e-tongue has been used to differentiate between orange juice made from healthy fruit and from fruit affected by the citrus greening or Huanglongbing (HLB disease. This study investigated the reaction of an e-tongue system to the main chemicals in orange juice that impact flavor and health benefits and are also impacted by HLB. Orange juice was spiked with sucrose (0.2–5.0 g/100 mL, citric acid (0.1%–3.0% g/100 mL and potassium chloride (0.1–3.0 g/100 mL as well as the secondary metabolites nomilin (1–30 µg/mL, limonin (1–30 µg/mL, limonin glucoside (30–200 µg/mL, hesperidin (30–400 µg/mL and hesperetin (30–400 µg/mL. Performance of Alpha MOS sensor sets #1 (pharmaceutical and #5 (food were compared for the same samples, with sensor set #1 generally giving better separation than sensor set #5 for sucrose, sensor set #5 giving better separation for nomilin and limonin, both sets being efficient at separating citric acid, potassium chloride, hesperitin and limonin glucoside, and neither set discriminating hesperidin efficiently. Orange juice made from fruit over the harvest season and from fruit harvested from healthy or HLB-affected trees were separated by harvest maturity, disease state and disease severity.

  19. Effects of vegetable juice powder concentration and storage time on some chemical and sensory quality attributes of uncured, emulsified cooked sausages.

    Science.gov (United States)

    Sindelar, J J; Cordray, J C; Sebranek, J G; Love, J A; Ahn, D U

    2007-06-01

    Uncured, no-nitrate/nitrite-added meat products can be manufactured with vegetable juice powder (VJP) and a starter culture containing Staphylococcus carnosus, resulting in quality and sensory attributes similar to traditional cured products. The 1st objective of this study was to determine the effects of varying concentrations of VJP and incubation times (MIN-HOLD) on quality characteristics, including lipid oxidation, color, and cured meat pigment concentrations, of emulsified-frankfurter-style-cooked (EFSC) sausages over a 90-d storage period. The 2nd objective was to compare residual nitrate and nitrite content resulting from different processing treatments and the 3rd objective was to assess sensory properties of finished products. Four EFSC sausage treatments (TRT) (TRT 1: 0.20% VJP, 30 MIN-HOLD; TRT 2: 0.20% VJP, 120 MIN-HOLD; TRT 3: 0.40% VJP, 30 MIN-HOLD; TRT 4: 0.40% VJP, 120 MIN-HOLD) and a sodium nitrite-added control (C) were used for this study. No differences for lipid oxidation (TBARS) between any TRTs and C or over time were observed. No differences (P > 0.05) for CIE L* values were found between TRTs. CIE a* and reflectance ratio values revealed that TRTs 2, 4, and C were redder than TRTs 1 and 3 at day 0. Trained sensory intensity ratings for cured aroma, cured color, cured flavor, uniform color, and firmness determined that all but TRT 1 were similar to C. These results indicate a longer incubation time (120 compared with 30 min) was found more critical than VJP level (0.20% or 0.40%) to result in products comparable to a sodium nitrite-added control.

  20. 地下水化学组分存在形式及其质量浓度的计算%Existing forms of groundwater chemical components and calculation to its mass concentration

    Institute of Scientific and Technical Information of China (English)

    胡筱; 张永祥; 王一凡; 张晓叶; 兰双双

    2015-01-01

    根据质量守恒定律以及化学热力学平衡常数法,建立了地下水水质组分存在形式及其质量浓度计算的数学模型,并利用MATLAB编写了相应程序,对北京市朝阳区地下水水质检测数据进行实例计算。结果表明:水中化学组分的存在形式包括单一离子、复阴离子、络合离子以及络合分子;游离态的Ca2+、Mg2+、SO2-4占各自离子总质量浓度的百分数分别为85.26%,87.01%,69.85%,表明水样分析质量浓度与计算质量浓度间存在差异;pH值对地下水中游离离子的质量浓度将产生影响,造成离子迁移能力的变化。%Based on the mass conservation law and the method of chemical thermodynamic equilibrium constant , a mathematical model for calculating the existing forms of groundwater chemical components and its mass concentration was established .Based on MATLAB , a corresponding program to calculate the groundwater quality testing data of Chaoyang District , Beijing was written .The results show that the existing forms of groundwater chemical components include single ions , complex anions , complex ions and complex molecules; Dissociative Ca2+, Mg2+, SO42-accounted for mass concentration of Ca 2+, Mg2+, SO42-, respectively, 85.26%,87.01%, 69.85%, which claims the difference between analysis concentration and calculated concentration; The value of pH exerts an influence on the concentration of free ions in groundwater , which causes the changes of ion migration ability.

  1. Eddy covariance fluxes and vertical concentration gradient measurements of NO and NO2 over a ponderosa pine ecosystem: observational evidence for within-canopy chemical removal of NOx

    Science.gov (United States)

    Min, K.-E.; Pusede, S. E.; Browne, E. C.; LaFranchi, B. W.; Cohen, R. C.

    2014-06-01

    Exchange of NOx (NO+NO2) between the atmosphere and biosphere is important for air quality, climate change, and ecosystem nutrient dynamics. There are few direct ecosystem-scale measurements of the direction and rate of atmosphere-biosphere exchange of NOx. As a result, a complete description of the processes affecting NOx following emission from soils and/or plants as they transit from within the plant/forest canopy to the free atmosphere remains poorly constrained and debated. Here, we describe measurements of NO and NO2 fluxes and vertical concentration gradients made during the Biosphere Effects on AeRosols and Photochemistry EXperiment 2009. In general, during daytime we observe upward fluxes of NO and NO2 with counter-gradient fluxes of NO. We find that NOx fluxes from the forest canopy are smaller than calculated using observed flux-gradient relationships for conserved tracers and also smaller than measured soil NO emissions. We interpret these differences as primarily due to chemistry converting NOx to higher nitrogen oxides within the forest canopy, which might be part of a mechanistic explanation for the "canopy reduction factor" applied to soil NOx emissions in large-scale models.

  2. Effect of pentachlorophenol and chemical oxygen demand mass concentrations in influent on operational behaviors of upflow anaerobic sludge blanket (UASB) reactor.

    Science.gov (United States)

    Shen, Dong-Sheng; He, Ruo; Liu, Xin-Wen; Long, Yan

    2006-08-25

    Upflow anaerobic sludge blanket (UASB) reactor that was seeded with anaerobic sludge acclimated to chlorophenols was used to investigate the feasibility of anaerobic biotreatment of synthetic wastewater containing pentachlorophenol (PCP) with additional sucrose as carbon source. Two sets of UASB reactors were operated at one time. But the seeded sludge for the two reactors was different and Reactor I was seeded with the sludge that was acclimated to PCP completely for half a year, and Reactor II was seeded with the mixed sludge that was acclimated for half a year to PCP, 4-CP, 3-CP or 2-CP, respectively. The degradation of PCP and the operation fee treating the wastewater are affected by the concentration of MEDS (microorganism easily degradable substrate). So the confirmation of the suitable ratio of [COD] and [PCP] was the key factor of treating the wastewater containing PCP economically and efficiently. During the experiment, the synthetic wastewater with 180.0 mg L(-1) PCP and 1250-10000 mg L(-1) COD could be treated steadily in the experimental Reactor I. The removal efficiency of PCP was more than 99.5% and the removal efficiency of COD was up to 90%. [PCP] (concentration of PCP) in effluent was less than 0.5 mg L(-1). [PCP] in influent could affect proper [COD] (concentration of COD) range in influent that was required for maintenance of steady running of the experimental reactor with a hydraulic retention time (HRT) from 20 to 22 h. [PCP] in influent would directly affect the necessary [COD] in influent when the UASB reactor ran normally and treated the wastewater containing PCP. When [PCP] was 100.4, 151.6 and 180.8 mg L(-1) in influent, respectively, [COD] in influent had to be controlled about 1250-7500, 2500-5000 and 5000 mg L(-1) to maintain the UASB reactor steady running normally and contemporarily ensure that [COD] and [PCP] in effluent were less than 300 and 0.5 mg L(-1), respectively. With the increase of [PCP] in influent, the range of variation

  3. Concentrated Ownership

    DEFF Research Database (Denmark)

    Rose, Caspar

    2014-01-01

    , especially minority shareholders. Concentrated ownership is associated with benefits and costs. Concentrated ownership may reduce agency costs by increased monitoring of top management. However, concentrated ownership may also provide dominating owners with private benefits of control....

  4. Significant concentration changes of chemical components of PM1 in the Yangtze River Delta area of China and the implications for the formation mechanism of heavy haze-fog pollution.

    Science.gov (United States)

    Zhang, Y W; Zhang, X Y; Zhang, Y M; Shen, X J; Sun, J Y; Ma, Q L; Yu, X M; Zhu, J L; Zhang, L; Che, H C

    2015-12-15

    Since the winter season of 2013, a number of persistent haze-fog events have occurred in central-eastern China. Continuous measurements of the chemical and physical properties of PM1 at a regional background station in the Yangtze River Delta area of China from 16 Nov. to 18 Dec., 2013 revealed several haze-fog events, among which a heavy haze-fog event occurred between 6 Dec. and 8 Dec. The mean concentration of PM1 was 212μgm(-3) in the heavy haze-fog period, which was about 10 times higher than on clean days and featured a peak mass concentration that reached 298μgm(-3). Organics were the largest contributor to the dramatic rise of PM1 on heavy haze-fog days (average mass concentration of 86μgm(-3)), followed by nitrate (58μgm(-3)), sulfate (35μgm(-3)), ammonium (29μgm(-3)), and chloride (4.0μgm(-3)). Nitrate exhibited the largest increase (~20 factors), associated with a significant increase in NOx. This was mainly attributable to increased coal combustion emissions, relative to motor vehicle emissions, and was caused by short-distance pollutant transport within surrounding areas. Low-volatility oxidized organic aerosols (OA) (LV-OOA) and biomass-burning OA (BBOA) also increased sharply on heavy haze-fog days, exhibiting an enhanced oxidation capacity of the atmosphere and increased emissions from biomass burning. The strengthening of the oxidation capacity during the heavy pollution episode, along with lower solar radiation, was probably due to increased biomass burning, which were important precursors of O3. The prevailing meteorological conditions, including low wind and high relative humidity, and short distance transported gaseous and particulate matter surrounding of the sampling site, coincided with the increased pollutant concentrations mainly from biomass-burning mentioned above to cause the persistent haze-fog event in the YRD area.

  5. Influence of physical and chemical properties of HTSXT-FTIR samples on the quality of prediction models developed to determine absolute concentrations of total proteins, carbohydrates and triglycerides: a preliminary study on the determination of their absolute concentrations in fresh microalgal biomass.

    Science.gov (United States)

    Serrano León, Esteban; Coat, Rémy; Moutel, Benjamin; Pruvost, Jérémy; Legrand, Jack; Gonçalves, Olivier

    2014-11-01

    Absolute concentrations of total macromolecules (triglycerides, proteins and carbohydrates) in microorganisms can be rapidly measured by FTIR spectroscopy, but caution is needed to avoid non-specific experimental bias. Here, we assess the limits within which this approach can be used on model solutions of macromolecules of interest. We used the Bruker HTSXT-FTIR system. Our results show that the solid deposits obtained after the sampling procedure present physical and chemical properties that influence the quality of the absolute concentration prediction models (univariate and multivariate). The accuracy of the models was degraded by a factor of 2 or 3 outside the recommended concentration interval of 0.5-35 µg spot(-1). Change occurred notably in the sample hydrogen bond network, which could, however, be controlled using an internal probe (pseudohalide anion). We also demonstrate that for aqueous solutions, accurate prediction of total carbohydrate quantities (in glucose equivalent) could not be made unless a constant amount of protein was added to the model solution (BSA). The results of the prediction model for more complex solutions, here with two components: glucose and BSA, were very encouraging, suggesting that this FTIR approach could be used as a rapid quantification method for mixtures of molecules of interest, provided the limits of use of the HTSXT-FTIR method are precisely known and respected. This last finding opens the way to direct quantification of total molecules of interest in more complex matrices.

  6. Control of residual carbon concentration in GaN high electron mobility transistor and realization of high-resistance GaN grown by metal-organic chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    He, X.G. [State Key Laboratory on Integrated Optoelectronics, Institute of Semiconductors, Chinese Academy of Sciences, P.O. Box 912, Beijing 100083 (China); Zhao, D.G., E-mail: dgzhao@red.semi.ac.cn [State Key Laboratory on Integrated Optoelectronics, Institute of Semiconductors, Chinese Academy of Sciences, P.O. Box 912, Beijing 100083 (China); Jiang, D.S.; Liu, Z.S.; Chen, P.; Le, L.C.; Yang, J.; Li, X.J. [State Key Laboratory on Integrated Optoelectronics, Institute of Semiconductors, Chinese Academy of Sciences, P.O. Box 912, Beijing 100083 (China); Zhang, S.M.; Zhu, J.J.; Wang, H.; Yang, H. [Suzhou Institute of Nano-tech and Nano-bionics, Chinese Academy of Sciences, Suzhou 215125 (China)

    2014-08-01

    GaN films were grown by metal-organic chemical vapor deposition (MOCVD) under various growth conditions. The influences of MOCVD growth parameters, i.e., growth pressure, ammonia (NH{sub 3}) flux, growth temperature, trimethyl-gallium flux and H{sub 2} flux, on residual carbon concentration ([C]) were systematically investigated. Secondary ion mass spectroscopy measurements show that [C] can be effectively modulated by growth conditions. Especially, it can increase by reducing growth pressure up to two orders of magnitude. High-resistance (HR) GaN epilayer with a resistivity over 1.0 × 10{sup 9} Ω·cm is achieved by reducing growth pressure. The mechanism of the formation of HR GaN epilayer is discussed. An Al{sub x}Ga{sub 1−x}N/GaN high electron mobility transistor structure with a HR GaN buffer layer and an additional low-carbon GaN channel layer is presented, exhibiting a high two dimensional electron gas mobility of 1815 cm{sup 2}/Vs. - Highlights: • Influence of MOCVD parameters on residual carbon concentration in GaN is studied. • GaN layer with a resistivity over 1 × 10{sup 9} Ω·cm is achieved by reducing growth pressure. • High electron mobility transistor (HEMT) structures were prepared. • Control of residual carbon content results in HEMT with high 2-D electron gas mobility.

  7. Chemical recognition software

    Energy Technology Data Exchange (ETDEWEB)

    Wagner, J.S.; Trahan, M.W.; Nelson, W.E.; Hargis, P.H. Jr.; Tisone, G.C.

    1994-06-01

    We have developed a capability to make real time concentration measurements of individual chemicals in a complex mixture using a multispectral laser remote sensing system. Our chemical recognition and analysis software consists of three parts: (1) a rigorous multivariate analysis package for quantitative concentration and uncertainty estimates, (2) a genetic optimizer which customizes and tailors the multivariate algorithm for a particular application, and (3) an intelligent neural net chemical filter which pre-selects from the chemical database to find the appropriate candidate chemicals for quantitative analyses by the multivariate algorithms, as well as providing a quick-look concentration estimate and consistency check. Detailed simulations using both laboratory fluorescence data and computer synthesized spectra indicate that our software can make accurate concentration estimates from complex multicomponent mixtures, even when the mixture is noisy and contaminated with unknowns.

  8. Chemical recognition software

    Energy Technology Data Exchange (ETDEWEB)

    Wagner, J.S.; Trahan, M.W.; Nelson, W.E.; Hargis, P.J. Jr.; Tisone, G.C.

    1994-12-01

    We have developed a capability to make real time concentration measurements of individual chemicals in a complex mixture using a multispectral laser remote sensing system. Our chemical recognition and analysis software consists of three parts: (1) a rigorous multivariate analysis package for quantitative concentration and uncertainty estimates, (2) a genetic optimizer which customizes and tailors the multivariate algorithm for a particular application, and (3) an intelligent neural net chemical filter which pre-selects from the chemical database to find the appropriate candidate chemicals for quantitative analyses by the multivariate algorithms, as well as providing a quick-look concentration estimate and consistency check. Detailed simulations using both laboratory fluorescence data and computer synthesized spectra indicate that our software can make accurate concentration estimates from complex multicomponent mixtures. even when the mixture is noisy and contaminated with unknowns.

  9. Impact of maritime transport on particulate matter concentrations and chemical compositions in four port-cities of the Adriatic/Ionian area: an overview of the results of POSEIDON project

    Science.gov (United States)

    Contini, Daniele; Gambaro, Andrea; Argiriou, Athanasios; Alebic-Juretic, Ana; Barbaro, Elena; Cesari, Daniela; Dimopoulos, Spiros; Dinoi, Adelaide; Donateo, Antonio; Gregoris, Elena; Karagiannidis, Athanasios; Ivosevic, Tatjana; Liora, Natalia; Melas, Dimitrios; Merico, Eva; Mifka, Boris; Orlic, Ivo; Poupkou, Anastasia; Sarovic, Kristina

    2015-04-01

    Pollutant emissions from ships and harbour activities constitute an important source of pollution of coastal areas with potential influences on the climate and the health of their inhabitants. A recent review (Viana et al., 2014) shows that these emissions could have an important impact on the Mediterranean and that there is a lack of data for the Eastern and South-Eastern part of this area. This work presents an analysis of the impact of ship emissions to atmospheric particle concentrations (PM) in four important port-cities (Patras Greece, Brindisi and Venice Italy, and Rijeka Croatia) of the Adriatic/Ionian area. The study was performed within the POSEIDON project (Pollution monitoring of ship emissions: an integrated approach for harbours of the Adriatic basin, funded within the MED Programme 2007-2013). The study uses an integrated approach using emission inventories, dispersion modelling and measurements taken at high temporal resolution (1 min) and low temporal resolution for chemical characterization of PM. The emission inventories of the four port-cities show that ships contribute between 11.7% and 31.0% of the total PM emissions being a source locally comparable with road traffic (ranging between 11.8% and 26.6%). The source apportionment using the receptor model PMF showed an oil combustion source (that includes ship emissions), characterized by V and Ni, in Brindisi, Venice and Rijeka with V/Ni ratio ranging between 1.4 and 4.2 indicating local differences in chemical profiles of the emissions. The V concentrations were used to evaluate the contributions of primary ship emissions to PM (Agrawal et al., 2009) that resulted between 1.3% and 2.8%. The contribution to secondary sulphate was 11% of PM2.5 in Brindisi (Cesari et al., 2014). The analysis of high-temporal resolution measurements taken near the harbour areas of Venice, Patras and Brindisi showed a contribution of ship emissions to PM2.5 varying between 3.5% and 7.4%. The relative contribution to

  10. Quantification Assessment of the Relationship Between Chemical and Olfactory Concentrations for Malodorous Volatile Organic Compounds%城市污水处理厂恶臭挥发性有机物的感官定量评价研究

    Institute of Scientific and Technical Information of China (English)

    刘舒乐; 王伯光; 何洁; 唐小东; 赵德骏; 郭薇

    2011-01-01

    Using self-made cold-traps and gas bags,the odor samples were collected from 6 sewage treatment workshops of a typical municipal sewage treatment plant in Guangzhou City.The chemical composition and olfactory concentrations of these samples were respectively analyzed by thermal-desorption/GC-MS and triangle odor bag method.Finally,a mathematical equation was built for assessing the relationship between principal organic odorants and the olfactory concentrations.The result showing that: ①More than 70 volatile organic compounds were detected in municipal sewage treatment plant,among which were 30 malodorous volatile organic compounds(MVOCs),ranging from 0.37 to 1 872.24 μg·m-3 and appearing in sludge dewatering,thickening and aeration tank with the highest concentrations.②Principle component analysis was used to group the target MVOCs into 5 categories: benzenes,halohydrocarbons,aldehydes,hydrocarbons and S,N-containing organic compounds.③Multiple lineal regression analysis was used to build a quantified relationship between chemical and olfactory concentrations of MVOCs.The result indicated that 25% of the odor problem of sewage treatment unit was due to MVOCs.The predicted values were fitting well with measured values.The sensitivity of mathematical equation for measuring odor concentration was higher than that of human olfactory system.%采用自制低温吸附装置和臭气袋采集了广州典型城市污水厂6个处理车间的空气样品.应用热解析/气相色谱-质谱联用仪分析恶臭挥发性有机物的组成和含量,参照国标的三点比较式臭袋法测量样品的恶臭浓度,并针对恶臭挥发性有机物进行感官定量评价.结果表明,①城市污水处理厂检测出烷烃、烯烃、芳香烃等7大类共70种挥发性有机物,其中30种属于恶臭挥发性有机物,它们的浓度范围为0.37~1 872.24μg.m-3,在污泥脱水、污泥浓缩和曝气池最高;②主成分分析可以将主要恶臭挥发

  11. Measurements of the concentration of major chemical species in the flame of a test burner with a air swirling system; Mesures de concentration d`especes chimiques majoritaires dans la flamme d`un bruleur modele avec mise en rotation de l`air

    Energy Technology Data Exchange (ETDEWEB)

    Albert, St. [Gaz de France (GDF), 93 - La Plaine-Saint-Denis (France); Most, J.M.; Poireault, B. [Centre National de la Recherche Scientifique (CNRS), 86 - Poitiers (France)

    1996-12-31

    The study of combustion in industrial burners remains difficult because of the complexity of the equipments used: materials geometry, tri-dimensional flows etc.. The phenomena that control the combustion in a gas burner with a swirl air system has been studied thanks to a collaboration between the Direction of Research of Gaz de France (GdF) and the Laboratory for Combustion and Detonation Research (LCD) of the French National Centre of Scientific Research (CNRS). The burner used is developed by the LCD and the measurements of stable chemical species were performed by the CERSTA centre of GdF. These series of tests, performed in confined environment, have permitted to identify some of the parameters that influence combustion chemistry. Mapping of chemical species allows to distinguish 5 zones of flame development and also the zones of nitrogen oxides formation. Methane is rapidly centrifuged a few millimeters above the injection pipe and centrifuged with rotating combustion air. Carbon monoxide occurs immediately in the central recirculation zone which is weakly reactive (no oxygen and no methane). Oxygen content increases downflow from this area and carbon dioxide reaches its concentration maxima. CO formation decreases when the swirl number increases and CO{sub 2} formation occurs earlier. On the contrary, the emissions of CO and CH{sub 4} do not depend on the swirl value and the NO{sub x} values are only slightly dependent on this value. (J.S.)

  12. The association of peripubertal serum concentrations of organochlorine chemicals and blood lead with growth and pubertal development in a longitudinal cohort of boys: a review of published results from the Russian Children's Study.

    Science.gov (United States)

    Sergeyev, Oleg; Burns, Jane S; Williams, Paige L; Korrick, Susan A; Lee, Mary M; Revich, Boris; Hauser, Russ

    2017-02-23

    Organochlorine chemicals and lead are environmental exposures that have endocrine disrupting properties (EDCs) which interfere with many aspects of hormone action. Childhood and adolescence are windows of susceptibility for adverse health effects of EDCs. Our ongoing study, the Russian Children's Study (RCS), is one of the few longitudinal studies investigating the impact of EDCs on growth and puberty in boys. It is conducted in the historically contaminated city of Chapaevsk, in the Samara region. The study focuses on evaluating the associations of persistent organochlorine chemicals and lead with growth and pubertal timing. At enrollment in 2003-2005, we collected blood from 516 boys at ages 8-9 years to measure dioxins, furans, polychlorinated biphenyls (PCBs), chlorinated pesticides and lead. At enrollment and at annual visits through the ages of 18-19 years, a physician performed physical examinations that included pubertal staging and testicular volume measurements. We review the history of Chapaevsk as a research site and summarize published RCS data on the association of peripubertal serum concentrations of organochlorines and blood lead levels with growth, pubertal onset and sexual maturity. Overall, we found that persistent organochlorines and lead negatively affected growth during puberty. Our results also suggest that total toxic equivalents (TEQs), dioxin-like compounds, organochlorine pesticides and lead may delay, while nondioxin-like-PCBs may advance, the timing of male puberty. These findings promoted remediation programs in Chapaevsk, with improvement in health indicators, resulting in Chapaevsk being designated a member of the World Health Organization (WHO) network "Healthy Cities" in 2015.

  13. Chemical Emergencies

    Science.gov (United States)

    When a hazardous chemical has been released, it may harm people's health. Chemical releases can be unintentional, as in the case of an ... the case of a terrorist attack with a chemical weapon. Some hazardous chemicals have been developed by ...

  14. Comparison of secondary organic aerosol formed with an aerosol flow reactor and environmental reaction chambers: effect of oxidant concentration, exposure time and seed particles on chemical composition and yield

    Directory of Open Access Journals (Sweden)

    A. T. Lambe

    2014-12-01

    Full Text Available We performed a systematic intercomparison study of the chemistry and yields of SOA generated from OH oxidation of a common set of gas-phase precursors in a Potential Aerosol Mass (PAM continuous flow reactor and several environmental chambers. In the flow reactor, SOA precursors were oxidized using OH concentrations ranging from 2.0×108 to 2.2×1010 molec cm−3 over exposure times of 100 s. In the environmental chambers, precursors were oxidized using OH concentrations ranging from 2×106 to 2×107 molec cm−3 over exposure times of several hours. The OH concentration in the chamber experiments is close to that found in the atmosphere, but the integrated OH exposure in the flow reactor can simulate atmospheric exposure times of multiple days compared to chamber exposure times of only a day or so. A linear correlation analysis of the mass spectra (m=0.91–0.92, r2=0.93–0.94 and carbon oxidation state (m=1.1, r2=0.58 of SOA produced in the flow reactor and environmental chambers for OH exposures of approximately 1011 molec cm−3 s suggests that the composition of SOA produced in the flow reactor and chambers is the same within experimental accuracy as measured with an aerosol mass spectrometer. This similarity in turn suggests that both in the flow reactor and in chambers, SOA chemical composition at low OH exposure is governed primarily by gas-phase OH oxidation of the precursors, rather than heterogeneous oxidation of the condensed particles. In general, SOA yields measured in the flow reactor are lower than measured in chambers for the range of equivalent OH exposures that can be measured in both the flow reactor and chambers. The influence of sulfate seed particles on isoprene SOA yield measurements was examined in the flow reactor. The studies show that seed particles increase the yield of SOA produced in flow reactors by a factor of 3 to 5 and may also account in part for higher SOA yields obtained in the chambers, where seed

  15. Combined effect of chemical pressure and valence electron concentration through the electron-deficient Li substitution on the RE{sub 4}LiGe{sub 4} (RE=La, Ce, Pr, and Sm) system

    Energy Technology Data Exchange (ETDEWEB)

    Nam, Gnu; Jeon, Jieun; Kim, Youngjo [Department of Chemistry, Chungbuk National University, Cheongju, Chungbuk 361-763 (Korea, Republic of); Kwon Kang, Sung [Department of Chemistry, Chungnam National University, Daejeon, Chungnam 305-764 (Korea, Republic of); Ahn, Kyunghan [Advanced Materials Research Center, Samsung Advanced Institute of Technology, Yongin-si, Gyeonggi-do 446-712 (Korea, Republic of); You, Tae-Soo, E-mail: tsyou@chungbuk.ac.kr [Department of Chemistry, Chungbuk National University, Cheongju, Chungbuk 361-763 (Korea, Republic of)

    2013-09-15

    Four members of the RE{sub 4}LiGe{sub 4} (RE=La, Ce, Pr, and Sm) system have been prepared by high-temperature reaction method and characterized by X-ray diffractions. All compounds crystallize in the orthorhombic Gd{sub 5}Si{sub 4}-type structure (space group Pnma, Pearson code oP16) with bonding interactions for interslab Ge{sub 2} dimers. The Li substitution for rare-earth elements in the RE{sub 4}LiGe{sub 4} system leads to a combined effect of the increased chemical pressure and the decreased valance electron concentration (VEC), which eventually results in the structure transformation from the Sm{sub 5}Ge{sub 4}-type with all broken interslab Ge–Ge bond for the parental RE{sub 5}Ge{sub 4} to the Gd{sub 5}Si{sub 4}-type structure for the ternary RE{sub 4}LiGe{sub 4} (RE=La, Ce, Pr, and Sm) system. Site-preference between rare-earth metals and Li is proven to generate energetically the most favorable atomic arrangements according to coloring-problem, and the rationale is provided using both the size-factor and the electronic-factor related, respectively, to site-volume and electronegativity as well as QVAL values. Tight-binding, linear-muffin-tin-orbital (TB-LMTO) calculations are performed to investigate electronic densities of states (DOS) and crystal orbital Hamilton population (COHP) curves. The influence of reduced VEC for chemical bonding including the formation of interslab Ge{sub 2} dimers is also discussed. The magnetic property measurements prove that the non-magnetic Li substitution leads to the ferromagnetic (FM)-like ground state for Ce{sub 4}LiGe{sub 4} and the co-existence of antiferromagntic (AFM) and FM ground states for Sm{sub 4}LiGe{sub 4}. - Graphical abstract: Reported is a combined effect of the chemical pressure and the reduced VEC caused by the smaller monovalent non-magnetic Li substitution for the larger trivalent magnetic rare-earth metals in the RE{sub 4}LiGe{sub 4} (RE=La, Ce, Pr, and Sm) system. This results in the structure

  16. Concentrating Radioactivity

    Science.gov (United States)

    Herrmann, Richard A.

    1974-01-01

    By concentrating radioactivity contained on luminous dials, a teacher can make a high reading source for classroom experiments on radiation. The preparation of the source and its uses are described. (DT)

  17. Multiple chemical sensitivity

    DEFF Research Database (Denmark)

    Tran, Marie Thi Dao; Arendt-Nielsen, Lars; Kupers, Ron;

    2013-01-01

    BACKGROUND: Multiple Chemical Sensitivity (MCS) is a chronic condition characterized by recurrent, non-specific symptoms in response to chemically unrelated exposures in non-toxic concentrations. Although the pathophysiology of MCS remains unknown, central sensitization may be an important factor...

  18. Effect of High Concentration of CO2 Invasion on Soil Physical and Chemical Properties%高浓度二氧化碳入侵对土壤理化性质的影响

    Institute of Scientific and Technical Information of China (English)

    裴宇; 赵晓红; 邓红章; 李春荣; 韩枫; 张青海; 张徽

    2016-01-01

    In the impact of the leakage of CO2 geological storage on the ecological environment, especially, the soil, it is the main medium of the exchange of substances and energy in ecological system, so studying the soil physical and chemical properties are very significant. This experiment artificially simulated the leakage of CO2 to the soil surface, and then the changes in soil organic carbon, nitrogen, phosphorus, potassium and water-soluble salts and the responses of plants were analyzed. The results show that, after the invasion of CO2, compared with the controlled area, the soil total organic carbon increases by 1.56%~43.75%, total nitrogen decreases by 0.88%~13.25%, ammonia and nitrate reduce as well, phosphorus, potassium and water-soluble salts also decline in general, while the pH of the soil is up,and every plant grows well, particularly, peas and radish. Conclusion:the invasion of high concentration of CO2 has some impacts on soil physical and chemical properties, in addition, can promote the growth of plants.%在地质储存CO2(GCS)泄漏对生态环境的影响中,土壤作为生态系统中物质与能量交换的主要介质,其理化性质的变化研究尤为重要。采用人工模拟CO2泄漏地表的方式,并分析土壤pH值、总有机碳、氮、磷、钾、水溶性盐浓度的变化及地表植物响应。结果表明:CO2入侵使土壤总有机碳相比于对照增加了1.56%~43.75%,总氮下降了0.88%~13.25%,氨氮与硝氮也同比下降,磷、钾、水溶性盐总体也是减少的,但土壤pH值有所上升,且各植物长势均较好,尤其是豌豆与萝卜的生长较好。结论:高浓度CO2入侵会对土壤理化性质产生一定影响,而且对植物的生长有促进作用。

  19. CHEMICAL BROMATOLOGIC COMPOSITION AND IN VITRO RUMINAL DIGESTIBILITY OF CONCENTRATES CONTAINING DIFFERENTS LEVELS OF SUNFLOWER QUACKER COMPOSIÇÃO BROMATOLÓGICA E DIGESTIBILIDADE RUMINAL IN VITRO DE CONCENTRADOS CONTENDO DIFERENTES NÍVEIS DE TORTA DE GIRASSOL

    Directory of Open Access Journals (Sweden)

    Mariana Stein

    2007-12-01

    Full Text Available

    The aim of this study was the evaluation of the chemical bromatologic composition and dry matter in vitro digestibility (DMIVD and crude protein in vitro digestibility (CPIVD of concentrates containing differents levels of sunflower quacker (SQ replacement soybean meal (SM as source of protein. Three different treatments were utilized: Control = C (concentrate containing SM, corn and mineral mixture; T25 = treatment C plus SQ replacing 25% of the crude protein of the SM, and T50 = treatment C plus SQ replacing 50% of the crude protein of the SM, were studied according to a completely randomized design with five replications. The results showed significant differences in the composition of the concentrates concerning crude fiber (CF, neutral detergent fiber (NDF, ether extract (EE, total digestible nutrients (TDN, total carbohydrates (TC and non-structural carbohydrates (NSC contents, considering the bovine nutrition in specially dairy cattle. Values of acid detergent fiber (ADF were very low. The averages obtained of CF, NDF and ADF were 4.95; 4.79 and 5.13%; 23.83; 23.88 and 27.03%; 5.08; 6.08 and 9.14% in order to C; T25 and T50, respectively. Values of dry matter (DM, crude protein (CP, mineral matter (MM, organic matter (OM, NDF, hemicelulose, nitrogen free extract (NFE, TDN, TC, and NFC averages did not differ between treatments (P>0.05. However, the T50 treatment produced higher CF, EE and ADF averages (P<0.01 in relation C and T25 treatments. The DMIVD averages presented a reduction with increased the levels substitution in the concentrates. The averages obtained of DMIVD coefficients were: 92.14; 85.42 and 85.09% respectively for the C; T25 and T50 treatments. The was no effect (P>0.05 with increase levels of SQ in the concentrates on the crude protein in vitro digestibility (CPDIV coefficients.  The averages of CPDIV coefficients were: 67.19; 63.16 and 71.62% respectively for the C; T25 and T50 treatments

  20. Tortuous path chemical preconcentrator

    Science.gov (United States)

    Manginell, Ronald P.; Lewis, Patrick R.; Adkins, Douglas R.; Wheeler, David R.; Simonson, Robert J.

    2010-09-21

    A non-planar, tortuous path chemical preconcentrator has a high internal surface area having a heatable sorptive coating that can be used to selectively collect and concentrate one or more chemical species of interest from a fluid stream that can be rapidly released as a concentrated plug into an analytical or microanalytical chain for separation and detection. The non-planar chemical preconcentrator comprises a sorptive support structure having a tortuous flow path. The tortuosity provides repeated twists, turns, and bends to the flow, thereby increasing the interfacial contact between sample fluid stream and the sorptive material. The tortuous path also provides more opportunities for desorption and readsorption of volatile species. Further, the thermal efficiency of the tortuous path chemical preconcentrator is comparable or superior to the prior non-planar chemical preconcentrator. Finally, the tortuosity can be varied in different directions to optimize flow rates during the adsorption and desorption phases of operation of the preconcentrator.

  1. Hydrogen Peroxide Concentrator

    Science.gov (United States)

    Parrish, Clyde F.

    2007-01-01

    A relatively simple and economical process and apparatus for concentrating hydrogen peroxide from aqueous solution at the point of use have been invented. The heart of the apparatus is a vessel comprising an outer shell containing tubular membranes made of a polymer that is significantly more permeable by water than by hydrogen peroxide. The aqueous solution of hydrogen peroxide to be concentrated is fed through the interstitial spaces between the tubular membranes. An initially dry sweep gas is pumped through the interiors of the tubular membranes. Water diffuses through the membranes and is carried away as water vapor mixed into the sweep gas. Because of the removal of water, the hydrogen peroxide solution flowing from the vessel at the outlet end is more concentrated than that fed into the vessel at the inlet end. The sweep gas can be air, nitrogen, or any other gas that can be conveniently supplied in dry form and does not react chemically with hydrogen peroxide.

  2. Composição centesimal do fruto, extrato concentrado e da farinha da uva-do-japão Chemical composition of fruit, concentrated extract and flour from "Japanese grape"

    Directory of Open Access Journals (Sweden)

    Marlene Bampi

    2010-11-01

    Full Text Available A Hovenia dulcis, mais conhecida como uva-do-japão, pertence à família Rhamnaceae, é natural da China, Japão e Coréia, sendo largamente difundida no sul do Brasil. Rica em açúcares e bem aceita para consumo humano, pode ser consumida in natura ou processada. Não há na literatura relatos de seu aproveitamento em produtos alimentícios. O presente trabalho teve por objetivo determinar a composição centesimal do fruto, do extrato concentrado e da farinha. Foram obtidos teores em torno de 54,08, 52,44 e 19,08g 100g-1 para umidade; 2,16, 4,09 e 4,48g 100g-1 para cinzas; 3,74, 2,77 e 5,73g 100g-1 para proteína bruta; 1,42, 0,37 e 1,82g 100g-1 para extrato etéreo; 12,56, 3,33 e 25,62g 100g-1 para fibra alimentar; 19,46, 37,34 e 42,53g 100g-1 para açúcares totais, além do valor calórico de 105,56, 165,14 e 216,09kcal 100g-1, respectivamente, em fruto, extrato concentrado e farinha. A quantificação por cromatografia líquida confirmou o conteúdo dos açúcares redutores (frutose, 6,15g 100g-1 e glicose, 6,57g 100g-1 superior ao teor de açúcares não redutores no fruto (sacarose, 3,56g 100g-1. A farinha é rica em açúcares e possui elevado teor de fibra alimentar, podendo ser utilizada como um ingrediente alternativo em produtos de panificação. Em termos sensoriais, o extrato concentrado obteve um índice de aceitabilidade de 82% entre os julgadores, apresentando bom potencial para elaboração de geleias.Hovenia dulcis, whose popular name is Japanese grape, belongs to the family Rhamnaceae, native of China, Japan and Korea, is widely distributed in southern Brazil. Rich in sugar and with good acceptance for human consumption it can be consumed fresh or processed. There are no literature reports of its use in food products. The aim of this study was to determine the chemical composition of the Japanese grape fruit, concentrated extract and flour. The contents for moisture (54.08, 52.44 e 19.08g 100g-1, ash (2.16, 4.09 e 4.48g

  3. Dissolved and labile concentrations of Cd, Cu, Pb, and Zn in the South Fork Coeur d'Alene River, Idaho: Comparisons among chemical equilibrium models and implications for biotic ligand models

    Science.gov (United States)

    Balistrieri, L.S.; Blank, R.G.

    2008-01-01

    In order to evaluate thermodynamic speciation calculations inherent in biotic ligand models, the speciation of dissolved Cd, Cu, Pb, and Zn in aquatic systems influenced by historical mining activities is examined using equilibrium computer models and the diffusive gradients in thin films (DGT) technique. Several metal/organic-matter complexation models, including WHAM VI, NICA-Donnan, and Stockholm Humic model (SHM), are used in combination with inorganic speciation models to calculate the thermodynamic speciation of dissolved metals and concentrations of metal associated with biotic ligands (e.g., fish gills). Maximum dynamic metal concentrations, determined from total dissolved metal concentrations and thermodynamic speciation calculations, are compared with labile metal concentrations measured by DGT to assess which metal/organic-matter complexation model best describes metal speciation and, thereby, biotic ligand speciation, in the studied systems. Results indicate that the choice of model that defines metal/organic-matter interactions does not affect calculated concentrations of Cd and Zn associated with biotic ligands for geochemical conditions in the study area, whereas concentrations of Cu and Pb associated with biotic ligands depend on whether the speciation calculations use WHAM VI, NICA-Donnan, or SHM. Agreement between labile metal concentrations and dynamic metal concentrations occurs when WHAM VI is used to calculate Cu speciation and SHM is used to calculate Pb speciation. Additional work in systems that contain wide ranges in concentrations of multiple metals should incorporate analytical speciation methods, such as DGT, to constrain the speciation component of biotic ligand models. ?? 2008 Elsevier Ltd.

  4. Cleaner concentrates

    Energy Technology Data Exchange (ETDEWEB)

    Boudechiche, S.; Hall, S. [University of Nottingham, Nottingham (United Kingdom)

    1995-06-01

    The desire for higher quality coal products in froth flotation has led to the introduction of a number of novel flotation techniques, including flotation columns, but the benefits of each in relation to the source of the slurry must be evaluated before plant is installed. It was to assess on a laboratory scale the quality of coal flotation concentrates from column flotation of fine coal (-500{mu}m) as an alternative to the traditional conventional agitated cell that this work was carried out. The column developed specifically for this purpose allowed the establishment of an approach to the examination of the flotation response of samples of UK coals (originating from Bolsover, Derbyshies; Rawdon, Leicestershire; and Bilsthorpe, Nottinghamshire). The work indicates the importance of the origin of the feed slurry, since each type of coal exhibits a different flotation response. The observations from the results described in this paper enable an assessment to be made of the merits of column flotation in fine coal treatment. 11 refs., 4 figs., 5 tabs.

  5. CHEMICALS AND REPRODUCTIVE HEALTH

    Directory of Open Access Journals (Sweden)

    Omer Faruk TEKBAS

    2006-02-01

    Full Text Available However a lot of chemicals had been used in our daily life, we have enough knowledge about the effects of only for a small portion of them on reproductive health. Our knowledge had been arisen from epidemiologic and experimental studies. In order to protect ourselves from chemicals in the environment it should be concentrate on experimental studies and the results of them should be carefully studied during epidemiological researches. It would be tried to tell about the main chemicals which had been known as effective on reproductive health on the following review. [TAF Prev Med Bull 2006; 5(1.000: 50-59

  6. SIZE DISTRIBUTION OF NUMBER CONCENTRATION AND CHEMICAL COMPONENTS OF PARTICULATE MATTERS DURING SPRING FESTIVAL IN SHANGHAI SUBURB%上海市郊春节期间大气颗粒物及其组分的粒径分布

    Institute of Scientific and Technical Information of China (English)

    王广华; 林俊; 姚剑; 范雪波; 耿彦红; 位楠楠; 刘卫; 李燕

    2011-01-01

    Number concentrations of particulate matters with different diameters (mass medium diameter: 0.03,0.06, 0.11,0.17, 0.26, 0.40, 0.65, 1.00, 1.60, 2.50, 4.40, 6.80 μn) were on-line monitored using an ELPI (electrical low pressure impactor) during 2009 Spring Festival in Jiading District, a suburb area in Shanghai. Several chemical components including 17 elements, 10 ions, organic and elemental carbon in particulate matters with different diameters ( < 0.49, 0. 49-0. 95 , 0. 95-1. 50 , 1.50-3.00, 3.00-7. 20,> 7.20 μn) were further determined. These particulate matters were collected on both the Spring Festival and ordinary days on the same sampling site. Experimental results showed that the influence of Festival Spring on the number concentrations was mainly on the particulate matters with size range of 0.11- 1.60 μm. If the particulate matters are divided into fine ( ≤ 3.00 μm) and coarse ( > 3.00 μm) ones by the diameter of 3.00 μm, it can be seen that the trace elements of Na, As and Pb in fine particulates were greatly affected by the Spring Festival and such effects appeared mainly in the particulate matter with size of < 0.49 μm. The trace elements of Ni, Co in coarse particles with size of > 7.20 μm were affected by the Spring Festival while Ca,V, Mn, Fe, Zn, Se didn't show significant effect of the Spring Festival. F-, SO24- , NH4+, K+ , Mg2+ in both fine and coarse particulates were influenced by the Spring Festival. K+ and Mg2+ were influenced seriously in fine particles, and C1-, NO-3, Na +, NO-2 and Ca2+ in coarse particles were influenced. The OC and EC were much higher in TSP during the Spring Festival than those on ordinary days, and the increases mainly occurred in the fine particles.%利用电称低压冲击仪(ELPI)在线监测上海市嘉定区2009年春节前后不同粒径(50%切割粒径分别为:0.03、0.06、0.11、0.17、0.26、0.40、0.65、1.00、1.60、2.50、4.40、6.80μm)大气颗粒物的粒子数浓度变化.对

  7. Chemical use

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This is a summary of research and activities related to chemical use on Neal Smith National Wildlife Refuge between 1992 and 2009. The chemicals used on the Refuge...

  8. Chemical Reactors.

    Science.gov (United States)

    Kenney, C. N.

    1980-01-01

    Describes a course, including content, reading list, and presentation on chemical reactors at Cambridge University, England. A brief comparison of chemical engineering education between the United States and England is also given. (JN)

  9. Carbon Concentration of Austenite

    Directory of Open Access Journals (Sweden)

    Z. Ławrynowicz

    2007-07-01

    Full Text Available The investigation was carried out to examine the influence of temperature and times of austempering process on the maximum extend towhich the bainite reaction can proceed and the carbon content in retained austenite. It should be noted that a small percentage change in theaustenite carbon content can have a significant effect on the subsequent austempering reaction changing the volume fraction of the phasespresent and hence, the resulting mechanical properties. Specimens were prepared from an unalloyed ductile cast iron, austenitised at 950oCfor 60 minutes and austempered by the conventional single-step austempering process at four temperatures between BS and MS, eg., 250,300, 350 and 400oC. The samples were austempered at these temperatures for 15, 30, 60, 120 and 240 minutes and finally quenched toambient temperature. Volume fractions of retained austenite and carbon concentration in the residual austenite have been observed byusing X-ray diffraction. Additionally, carbon concentration in the residual austenite was calculated using volume fraction data of austeniteand a model developed by Bhadeshia based on the McLellan and Dunn quasi-chemical thermodynamic model. The comparison ofexperimental data with the T0, T0' and Ae3' phase boundaries suggests the likely mechanism of bainite reaction in cast iron is displacive rather than diffusional. The carbon concentration in retained austenite demonstrates that at the end of bainite reaction the microstructure must consist of not only ausferrite but additionally precipitated carbides.

  10. The relationship between aerosol particles chemical composition and optical properties to identify the biomass burning contribution to fine particles concentration: a case study for São Paulo city, Brazil.

    Science.gov (United States)

    de Miranda, Regina Maura; Lopes, Fabio; do Rosário, Nilton Évora; Yamasoe, Marcia Akemi; Landulfo, Eduardo; de Fatima Andrade, Maria

    2016-12-01

    The air quality in the Metropolitan Area of São Paulo (MASP) is primarily determined by the local pollution source contribution, mainly the vehicular fleet, but there is a concern about the role of remote sources to the fine mode particles (PM2.5) concentration and composition. One of the most important remote sources of atmospheric aerosol is the biomass burning emissions from São Paulo state's inland and from the central and north portions of Brazil. This study presents a synergy of different measurements of atmospheric aerosol chemistry and optical properties in the MASP in order to show how they can be used as a tool to identify particles from local and remote sources. For the clear identification of the local and remote source contribution, aerosol properties measurements at surface level were combined with vertical profiles information. Over 15 days in the austral winter of 2012, particulate matter (PM) was collected using a cascade impactor and a Partisol sampler in São Paulo City. Mass concentrations were determined by gravimetry, black carbon concentrations by reflectance, and trace element concentrations by X-ray fluorescence. Aerosol optical properties were studied using a multifilter rotating shadowband radiometer (MFRSR), a Lidar system and satellite data. Optical properties, concentrations, size distributions, and elemental composition of atmospheric particles were strongly related and varied according to meteorological conditions. During the sampling period, PM mean mass concentrations were 17.4 ± 10.1 and 15.3 ± 6.9 μg/m(3) for the fine and coarse fractions, respectively. The mean aerosol optical depths at 415 nm and Ångström exponent (AE) over the whole period were 0.29 ± 0.14 and 1.35 ± 0.11, respectively. Lidar ratios reached values of 75 sr. The analyses of the impacts of an event of biomass burning smoke transport to the São Paulo city revealed significant changing on local aerosol concentrations and optical parameters

  11. Chemical ecology of marine sponges

    Digital Repository Service at National Institute of Oceanography (India)

    Thakur, N.L.; Singh, A.

    proto- cols of chemical isolation, and the estimation of natural concentration might not be a true repre- sentative of actual concentrations of the natural product in this sponge (Ma et al. 2009). Besides chemical clues, visual clues such as colour... of the prey can also determine the feeding behaviour. One of the major predators of Antarctic sponges is sea stars which lack visual organ. It was hypo- thesized that the present-day Antarctic sponges still retain visual pigments (e.g. discorhabdins...

  12. Chimistry and concentration of solar radiation

    Energy Technology Data Exchange (ETDEWEB)

    Vialaron, A.

    1981-08-01

    Some data concerning solar radiation and chemical thermodynamics are reviewed, taking into account technological considerations related to industrial reactors. Finally, the advantage of thermal or thermochemical solar devices working with concentrated fluxes is shown.

  13. Data for the size of cholesterol-fat micelles as a function of bile salt concentration and the physico-chemical properties of six liquid experimental pine-derived phytosterol formulations in a cholesterol-containing artificial intestine fluid

    Directory of Open Access Journals (Sweden)

    Jinsoo Yi

    2017-02-01

    Full Text Available The data in this paper are additional information to the research article entiltled “Inhibition of cholesterol transport in an intestine cell model by pine-derived phytosterols” (Yi et al.,2016 [1]. The data derived from the measurement on six liquid formulations of commercial pine-derived phytosterol (CPP by dynamic light scattering. The data cover micelle size and the zeta-potential for formulations with cholesterol including monoglyceride, oleic acid, and bile salt. The data demonstrate the critical effect of the bile salt concentration on the size of cholesterol-digested fat micelles.

  14. Magnetic chemically peculiar stars

    CERN Document Server

    Schöller, Markus

    2015-01-01

    Chemically peculiar (CP) stars are main-sequence A and B stars with abnormally strong or weak lines for certain elements. They generally have magnetic fields and all observables tend to vary with the same period. Chemically peculiar stars provide a wealth of information; they are natural atomic and magnetic laboratories. After a brief historical overview, we discuss the general properties of the magnetic fields in CP stars, describe the oblique rotator model, explain the dependence of the magnetic field strength on the rotation, and concentrate at the end on HgMn stars.

  15. Chemical intolerance

    DEFF Research Database (Denmark)

    Dantoft, Thomas Meinertz; Andersson, Linus; Nordin, Steven;

    2015-01-01

    Chemical intolerance (CI) is a term used to describe a condition in which the sufferer experiences a complex array of recurrent unspecific symptoms attributed to low-level chemical exposure that most people regard as unproblematic. Severe CI constitutes the distinguishing feature of multiple...... chemical sensitivity (MCS). The symptoms reported by CI subjects are manifold, involving symptoms from multiple organs systems. In severe cases of CI, the condition can cause considerable life-style limitations with severe social, occupational and economic consequences. As no diagnostic tools for CI...

  16. Hazardous Chemicals

    Centers for Disease Control (CDC) Podcasts

    2007-04-10

    Chemicals are a part of our daily lives, providing many products and modern conveniences. With more than three decades of experience, The Centers for Disease Control and Prevention (CDC) has been in the forefront of efforts to protect and assess people's exposure to environmental and hazardous chemicals. This report provides information about hazardous chemicals and useful tips on how to protect you and your family from harmful exposure.  Created: 4/10/2007 by CDC National Center for Environmental Health.   Date Released: 4/13/2007.

  17. Obtenção e caracterização química e nutricional de diferentes concentrados de caseína Obtention and chemical and nutritional characterization of different bovine casein concentrates

    Directory of Open Access Journals (Sweden)

    Janesca Alban Roman

    2005-02-01

    aos demais concentrados, quanto aos índices quociente de eficiência líquida da proteína e quociente de eficiência protéica operacional.OBJETIVE: The objective of the present work was to evaluate the centesimal composition, the amino acid profile and the the composition and nutritive value of three casein concentrates, obtained by different methods. METHODS: The casein concentrates were analysed according to the following methods: a commercial casein obtained by acid precipitation (pI followed by neutralization; an enzyme coagulated casein obtained by rennet coagulation; and a casein micelles concentrate obtained by microlfiltration and diafiltration. The Centesimal composition was determined by the procedures described in the manual Official Methods of Analysis. The amino acid profiles were determined after the protein acid hydrolysis (HCl 6N, 105°C, 22h in an amino acid autoanalyzer by cation exchange chromatography and post-column ninhydrin reaction. The essential amino acids were in accordance with Food and Agriculture Organization/World Health Organization recommendation for children 2 to 5 years of age. The nutritive value was determined on 21-day old rats of the Wistar strain through apparent net protein ratio, and protein efficiency ratio operational. RESULTS: Commercial casein presented higher protein concentration (92.0% than micellar casein (86.0% and casein clot (72.0%. The animals in the various protein diets did not show significant differences as to body weight gain and diet consumption. The highest digestibility was that of commercial casein (93.8%, compared to the other two concentrates (91.0%. CONCLUSION: The casein concentrates showed differences related to the centesimal composition, since the commercial casein presented a higher protein concentration. The casein clot was inferior to the other protein concentrates regarding net protein ratio and protein efficiency ratio operational.

  18. Determinação potenciométrica da concentração micelar crítica de surfactantes: uma nova aplicação metodológica no ensino de Química Potenciometric determination of the critical micellar concentration of the surfactants: a new methodological application in the Chemical learning

    Directory of Open Access Journals (Sweden)

    Ivanise Mª Rizzatti

    2009-01-01

    Full Text Available The participation of the students in the planning, execution and discussion of experimental results is important for the valuation of the role of them in the construction of the chemical knowledge implicited in the approach between education and research. This work relates either the construction of selective membrane electrodes for surfactants and its application in the potenciometric determination of the critical micellar concentration of the sodium dodecyl sulfate (SDS and dodecyltrimethylammonium bromide (DTAB surfactants. In adition it´s possible to discuss the potenciometric results in matching with the data valued for the tensiometric and condutimetric traditionally used in the physical-chemistry lessons.

  19. 21 CFR 1310.13 - Exemption of chemical mixtures; application.

    Science.gov (United States)

    2010-04-01

    ...-listed chemicals); or (ii) If a group of mixtures, the concentration range for the listed chemical and a listing of all non-listed chemicals with respective concentration ranges. (5) (i) The chemical and... file written comments on or objections to the order. If any comments or objections raise...

  20. Extended range chemical sensing apparatus

    Science.gov (United States)

    Hughes, Robert C.; Schubert, W. Kent

    1994-01-01

    An apparatus for sensing chemicals over extended range of concentrations. In particular, first and second sensors each having separate, but overlapping ranges for sensing concentrations of hydrogen are provided. Preferably, the first sensor is a MOS solid state device wherein the metal electrode or gate is a nickel alloy. The second sensor is a chemiresistor comprising a nickel alloy.

  1. Chemical Sensing with Nanowires

    Science.gov (United States)

    Penner, Reginald M.

    2012-07-01

    Transformational advances in the performance of nanowire-based chemical sensors and biosensors have been achieved over the past two to three years. These advances have arisen from a better understanding of the mechanisms of transduction operating in these devices, innovations in nanowire fabrication, and improved methods for incorporating receptors into or onto nanowires. Nanowire-based biosensors have detected DNA in undiluted physiological saline. For silicon nanowire nucleic acid sensors, higher sensitivities have been obtained by eliminating the passivating oxide layer on the nanowire surface and by substituting uncharged protein nucleic acids for DNA as the capture strands. Biosensors for peptide and protein cancer markers, based on both semiconductor nanowires and nanowires of conductive polymers, have detected these targets at physiologically relevant concentrations in both blood plasma and whole blood. Nanowire chemical sensors have also detected several gases at the parts-per-million level. This review discusses these and other recent advances, concentrating on work published in the past three years.

  2. Chemical aerosol Raman detector

    Science.gov (United States)

    Aggarwal, R. L.; Farrar, L. W.; Di Cecca, S.; Amin, M.; Perkins, B. G.; Clark, M. L.; Jeys, T. H.; Sickenberger, D. W.; D'Amico, F. M.; Emmons, E. D.; Christesen, S. D.; Kreis, R. J.; Kilper, G. K.

    2017-03-01

    A sensitive chemical aerosol Raman detector (CARD) has been developed for the trace detection and identification of chemical particles in the ambient atmosphere. CARD includes an improved aerosol concentrator with a concentration factor of about 40 and a CCD camera for improved detection sensitivity. Aerosolized isovanillin, which is relatively safe, has been used to characterize the performance of the CARD. The limit of detection (SNR = 10) for isovanillin in 15 s has been determined to be 1.6 pg/cm3, which corresponds to 6.3 × 109 molecules/cm3 or 0.26 ppb. While less sensitive, CARD can also detect gases. This paper provides a more detailed description of the CARD hardware and detection algorithm than has previously been published.

  3. Modeling the effects of type and concentration of organic modifiers, column type and chemical structure of analytes on the retention in reversed phase liquid chromatography using a single model.

    Science.gov (United States)

    Jouyban, Abolghasem; Soltani, Somaieh; Shayanfar, Ali; Pappa-Louisi, Adriani

    2011-09-16

    A previously proposed model for representing the retention factor (k) of an analyte in mixed solvent mobile phases was extended to calculate the k of different analytes with respect to the nature of analyte, organic modifier, its concentration and type of the stationary phase. The accuracy of the proposed method was evaluated by calculating mean percentage deviation (MPD) as accuracy criterion. The predicted vs. observed plots were also provided as goodness of fit criteria. The developed model prediction capability compared with a number of previous models (i.e. LSER, general LSER and Oscik equation) through MPD and fitting plots. The proposed method provided acceptable predictions with the advantage of modeling the effects of organic modifiers, mobile phase compositions, columns and analytes using a single equation. The accuracy of developed model was checked using the one column and one analyte out cross validation analyses and the results showed that the developed model was able to predict the unknown analyte retention and the analytes retentions on unknown column accurately.

  4. Influence of Mg concentration on physico-chemical properties of Cd ferrites (CdMg{sub 1.5x}Fe{sub 2−x}O{sub 4}) synthesized by sol–gel combustion method

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, Munish [Department of Chemistry, Centre for Advanced Studies-II, Guru Nanak Dev University, Amritsar, Punjab 143005 (India); Department of Chemistry, D A V College, Amritsar, Punjab 143001 (India); Gupta, Manik, E-mail: manuchemistry@gmail.com [Department of Chemistry, Guru Gobind Singh College, Chandigarh 160019 (India); Randhawa, B.S., E-mail: balwinderrandhawa@yahoo.co.in [Department of Chemistry, Centre for Advanced Studies-II, Guru Nanak Dev University, Amritsar, Punjab 143005 (India)

    2015-03-25

    Highlights: • Highly crystalline, single phase ferrites are obtained. • Saturation magnetization increases with increase in Mg{sup 2+} doping up to x = 0.7. • Nanosized particles tend to form inverted spinel structure. • Ferrites obtained have large surface area. - Abstract: The nanofabrication, characterization, microstructural and magnetic properties of pure and Mg{sup 2+} doped cadmium ferrite (CdFe{sub 2−x}Mg{sub 1.5x}O{sub 4}; x = 0.0–0.7) have been carried out. Morphology and the microstructure of the nanostructured oxide materials obtained through sol–gel process using hydrated metal-citrate precursor were studied by powder X-ray diffraction (XRD), electron microscopy (SEM, TEM) and N{sub 2}-physisorption (BET) showing an ordered cubic arrangement of 11–23 nm diameter pores with single-phase spinel grains averaging 13–38 nm in diameter. Room temperature magnetic measurements using magnetometer (VSM) demonstrate that the nature and concentration of dopant both control the site preference in the crystal lattices, suggesting the partial inverted spinel structure of soft Cd ferrites, which differs from bulk CdFe{sub 2}O{sub 4} showing practically no inversion in structure. An increase in Mg{sup 2+} substitution leads to a decrease in the lattice parameter, an increase in saturation magnetization as well as BET surface area of the as-synthesized ferrites.

  5. Chemical Mahjong

    Science.gov (United States)

    Cossairt, Travis J.; Grubbs, W. Tandy

    2011-01-01

    An open-access, Web-based mnemonic game is described whereby introductory chemistry knowledge is tested using mahjong solitaire game play. Several tile sets and board layouts are included that are themed upon different chemical topics. Introductory tile sets can be selected that prompt the player to match element names to symbols and metric…

  6. Chemical dispersants

    NARCIS (Netherlands)

    Rahsepar, Shokouhalsadat; Smit, Martijn P.J.; Murk, Albertinka J.; Rijnaarts, Huub H.M.; Langenhoff, Alette A.M.

    2016-01-01

    Chemical dispersants were used in response to the Deepwater Horizon oil spill in the Gulf of Mexico, both at the sea surface and the wellhead. Their effect on oil biodegradation is unclear, as studies showed both inhibition and enhancement. This study addresses the effect of Corexit on oil biodeg

  7. A Multimedia Model for Prediction of Chemicals Concentration Changes in Sediment-Water Microcosm Systems%预测沉积物-水微宇宙系统中化学品浓度变化的多介质模型

    Institute of Scientific and Technical Information of China (English)

    莫俊超; 舒耀皋; 董晶; 郭丹丹; 范宾; 刘刚

    2015-01-01

    Sediment-water microcosm system, which is one of the recommended test systems in the OECD guide-lines for the testing of chemicals, can be used to test chronic toxicity of chemicals to sediment-dwelling organisms. Before test performance, it is necessary to predict chemicals concentration changes and then confirm test method. This study aimed to build a mathematical model for this prediction. The model, parameterized for chironomid chro-nic toxicity test system as an example, could predict chemicals concentration changes in the sediment-water test system by chemical properties and test system parameters using multimedia environmental modeling approach. Combined with test data and documentation, recommended values were put forward for test system parameters in the model. The model was programmed and solved by Simulink tools in Matlab software. Based on the model, its three application fields were given, e.g. predicting accumulation period, equilibration period and matching test data. And then accumulation and equilibration periods of 80 existing or hypothetical chemicals were calculated, and scopes were<1-204 d and<1-73 d respectively. In addition, via modifying model structures and parameters proper-ly, the model could also be applied in other exposure scenarios. However, when predicting chemicals concentra-tions, the model could only give relatively accurate results for chemicals concentration in sediment and the results for that in water deviated from the measured values by 1-2 order of magnitudes, which still needs to be improved further. The results presented in this study perfect the sediment-water microcosm system test method.%沉积物-水微宇宙系统是经济合作发展组织(Organisation for Economic Co-Operation and Development, OECD)颁布的化学品测试准则中推荐的试验系统之一,可用来测试化学品对底栖生物的慢性毒性。为了在试验前对化学品的浓度变化进行预测,进而确定试验方法,以摇蚊慢性毒

  8. Chemical carcinogenesis

    Directory of Open Access Journals (Sweden)

    Paula A. Oliveira

    2007-12-01

    Full Text Available The use of chemical compounds benefits society in a number of ways. Pesticides, for instance, enable foodstuffs to be produced in sufficient quantities to satisfy the needs of millions of people, a condition that has led to an increase in levels of life expectancy. Yet, at times, these benefits are offset by certain disadvantages, notably the toxic side effects of the chemical compounds used. Exposure to these compounds can have varying effects, ranging from instant death to a gradual process of chemical carcinogenesis. There are three stages involved in chemical carcinogenesis. These are defined as initiation, promotion and progression. Each of these stages is characterised by morphological and biochemical modifications and result from genetic and/or epigenetic alterations. These genetic modifications include: mutations in genes that control cell proliferation, cell death and DNA repair - i.e. mutations in proto-oncogenes and tumour suppressing genes. The epigenetic factors, also considered as being non-genetic in character, can also contribute to carcinogenesis via epigenetic mechanisms which silence gene expression. The control of responses to carcinogenesis through the application of several chemical, biochemical and biological techniques facilitates the identification of those basic mechanisms involved in neoplasic development. Experimental assays with laboratory animals, epidemiological studies and quick tests enable the identification of carcinogenic compounds, the dissection of many aspects of carcinogenesis, and the establishment of effective strategies to prevent the cancer which results from exposure to chemicals.A sociedade obtém numerosos benefícios da utilização de compostos químicos. A aplicação dos pesticidas, por exemplo, permitiu obter alimento em quantidade suficiente para satisfazer as necessidades alimentares de milhões de pessoas, condição relacionada com o aumento da esperança de vida. Os benefícios estão, por

  9. Chemical cosmology

    CERN Document Server

    Boeyens, Jan CA

    2010-01-01

    The composition of the most remote objects brought into view by the Hubble telescope can no longer be reconciled with the nucleogenesis of standard cosmology and the alternative explanation, in terms of the LAMBDA-Cold-Dark-Matter model, has no recognizable chemical basis. A more rational scheme, based on the chemistry and periodicity of atomic matter, opens up an exciting new interpretation of the cosmos in terms of projective geometry and general relativity. The response of atomic structure to environmental pressure predicts non-Doppler cosmical redshifts and equilibrium nucleogenesis by alp

  10. Photoacoustic method for measuring concentration of chemical species

    Science.gov (United States)

    Autrey, S Thomas [West Richland, WA; Posakony, Gerald J [Richland, WA; Amonette, James E [Richland, WA; Foster-Mills, Nancy S [Richland, WA

    2001-01-01

    The present invention is a transducer for photoacoustic detection having at least two piezoelectric elements wherein at least a first piezoelectric element has a first frequency and at least a second piezoelectric element has a second frequency. The improvement according to the present invention is that at least two piezoelectric elements are longitudinal elements for longitudinal waves; and the first frequency is different from said second frequency. In other words, the invention is a multi-frequency longitudinal transducer for photoacoustic detection.

  11. Chemical logging of geothermal wells

    Science.gov (United States)

    Allen, C.A.; McAtee, R.E.

    The presence of geothermal aquifers can be detected while drilling in geothermal formations by maintaining a chemical log of the ratio of the concentrations of calcium to carbonate and bicarbonate ions in the return drilling fluid. A continuous increase in the ratio of the concentrations of calcium to carbonate and bicarbonate ions is indicative of the existence of a warm or hot geothermal aquifer at some increased depth.

  12. Chemical Principles Revisited: Chemical Equilibrium.

    Science.gov (United States)

    Mickey, Charles D.

    1980-01-01

    Describes: (1) Law of Mass Action; (2) equilibrium constant and ideal behavior; (3) general form of the equilibrium constant; (4) forward and reverse reactions; (5) factors influencing equilibrium; (6) Le Chatelier's principle; (7) effects of temperature, changing concentration, and pressure on equilibrium; and (8) catalysts and equilibrium. (JN)

  13. Determination of the chemical composition and functional properties of shrimp waste protein concentrate and lyophilized flour Determinação da composição química e das propriedades funcionais de concentrado protéico e de farinha liofilizada de resíduos de camarão

    Directory of Open Access Journals (Sweden)

    Olivaldo Lacerda Brasileiro

    2012-04-01

    Full Text Available Wastes from the seafood industry can be easily processed into products with new forms of use. The present study was aimed at determining the chemical composition and functional properties of shrimp waste protein concentrate and lyophilized flour. The raw material used in this study consisted of waste (head of Litopenaeus vannamei. The protein concentrate was obtained by ethanolic extraction, being subsequently submitted to drying in oven at 70° C, while the flour was obtained by lyophilization of shrimp wastes. Moisture, ash, protein and calcium contents showed significant difference between fresh shrimp head waste samples (IN and protein concentrate and lyophilized flour samples. The protein content for protein concentrate (PC and lyophilized flour (LF showed significant increase in relation to protein content in the waste (IN, thus showing that the process for obtaining the protein concentrate was efficient.Resíduos provenientes da indústria do pescado podem ser facilmente transformados em produtos com novas formas de aproveitamento. No presente estudo, objetivou-se determinar a composição química e as propriedades funcionais de farinha liofilizada e concentrado proteico provenientes de resíduos de camarão. A matéria-prima empregada neste estudo foi constituída de resíduos (cabeça de camarão Litopenaeus vannamei. O concentrado proteico foi obtido por extração etanólica e, posteriormente, submetido à secagem em estufa a 70° C, enquanto a farinha foi obtida pelo processo de liofilização do resíduo. Os teores de umidade, cinzas, proteínas e cálcio apresentaram diferença significativa entre as amostras de resíduo de cabeça de camarão in natura (IN e as amostras de concentrado proteico e farinha liofilizada. O teor de proteínas para concentrado protéico (CP e para a farinha liofilizada (FL apresentou aumento significativo em relação ao teor proteico do resíduo (IN, mostrando, assim, que o processo de elaboração do

  14. Composição química e perfil de ácidos graxos da carne de bovinos de diferentes condições sexuais recebendo silagem de milho e concentrado ou cana-de-açúcar e concentrado contendo grãos de girassol Chemical traits and fatty acids composition of beef from young bulls, steers and heifers fed corn silage and concentrate or sugarcane and concentrate with sunflower grains

    Directory of Open Access Journals (Sweden)

    Alexandre Rodrigo Mendes Fernandes

    2009-04-01

    Full Text Available O objetivo neste trabalho foi avaliar as características químicas e a composição em ácidos graxos do contrafilé (músculo Longissimus de tourinhos, novilhos e novilhas da raça Canchim. Os animais foram terminados em confinamento com duas dietas experimentais, uma com silagem de milho e concentrado e outra com cana-de-açúcar e concentrado contendo grãos de girassol. Os teores de umidade, proteína e minerais no músculo não diferiram entre as dietas e as condições sexuais dos animais. A carne de novilhos terminados com a dieta com grãos de girassol apresentou maior teor de lipídios (3,31% em comparação à dos animais de outras categorias. Os animais que receberam a dieta com grãos de girassol apresentaram maiores concentrações de ácido linoléico conjugado (18:2 cis9, trans-11 (0,73% e ácidos graxos poliinsaturados (8,12% no músculo, e também relações mais elevadas de ácidos graxos insaturados:saturados (0,93 e ácidos graxos poliinsaturados:saturados (0,16 em comparação àqueles que receberam a dieta convencional, à base de silagem de milho (0,34%; 6,31%; 0,86; e 0,11, respectivamente. A composição em ácidos graxos da carne de bovinos pode ser melhorada com a utilização de cana-de-açúcar e grãos de girassol na dieta dos animais terminados em confinamento.The objective in this work was to evaluate the chemical characteristics and the fatty acids composition of beef loin (Longissimus muscle of young bulls, steers and heifers of Canchim breed. The animals were finished in feedlot system and fed two experimental diets, one with corn silage and concentrate (SIL and the other with sugar cane, as exclusive roughage, and concentrate containing sunflower grains (CNA. Differences were not detected in relation to moisture, protein and mineral contents between diets or sexual categories. The meat from steers that received the CNA diet had higher lipid content (3.31% in relation to meat from young bulls and heifers

  15. Chemical Analyses

    Science.gov (United States)

    Bulluck, J. W.; Rushing, R. A.

    1994-01-01

    As a preliminary study on the effects of chemical aging of polymer materials MERL and TRI have examined two polymeric materials that are typically used for offshore umbilical applications. These two materials were Tefzel, a copolymer of ethylene and tetrafluoroethylene, and Coflon, polyvinylidene fluoride. The Coflon specimens were cut from pipe sections and exposed to H2S at various temperatures and pressures. One of these specimens was tested for methane permeation, and another for H2S permeation. The Tefzel specimens were cut from .05 mm sheet stock material and were exposed to methanol at elevated temperature and pressure. One of these specimens was exposed to methanol permeation for 2 days at 100 C and 2500 psi. An additional specimen was exposed to liquid methanol for 3 days at 150 C and 15 Bar. Virgin specimens of each material were similarly prepared and tested.

  16. Sustainability in Chemical Engineering Curriculum

    Science.gov (United States)

    Glassey, Jarka; Haile, Sue

    2012-01-01

    Purpose: The purpose of this paper is to describe a concentrated strategy to embed sustainability teaching into a (chemical) engineering undergraduate curriculum throughout the whole programme. Innovative teaching approaches in subject-specific context are described and their efficiency investigated. Design/methodology/approach: The activities in…

  17. Toxicokinetic Triage for Environmental Chemicals

    Science.gov (United States)

    Toxicokinetic (TK) models are essential for linking administered doses to blood and tissue concentrations. In vitro-to-in vivo extrapolation (IVIVE) methods have been developed to determine TK from limited in vitro measurements and chemical structure-based property predictions, p...

  18. Safe use of hazardous chemicals.

    Science.gov (United States)

    Lunn, George; Lawler, Gretchen

    2011-11-01

    This unit provides protocols for some commonly used disposal and decontamination procedures along with analytical techniques that are used to verify that reagents have been decontaminated. Some of the specific reagents covered are diaminobenzidine, ethidium bromide, cyanogen bromide, and chloromethylsilane. With modification, these assays may also be used to determine the concentration of a particular chemical.

  19. National Geochemical Database: Concentrate

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Geochemistry of concentrates from the National Geochemical Database. Primarily inorganic elemental concentrations, most samples are from the continental US and...

  20. Photovoltaics. III - Concentrators

    Science.gov (United States)

    Backus, C. E.

    1980-02-01

    Photovoltaic concentration systems that redirect sunlight falling on a surface to a smaller solar-cell surface concentrating the intensity of sunlight many times are examined. It is noted that solar cells for concentrating systems must be designed for low internal resistance as well as for high sunlight intensities. Two designs of silicon cells are presented that perform well at high concentrations; these are interdigitated back-contact cells and vertical multijunction cells. Attention is given to heat tapping of reemitted light.

  1. When is Concentration Beneficial?

    OpenAIRE

    Liron-Espana, Carmen; Lopez, Rigoberto A.

    2001-01-01

    This paper separates market power and efficiency effects of concentration in a sample of 255 U.S. manufacturing industries and computes welfare changes from rises in concentration. The empirical findings reveal that in nearly two-third of the cases, consumers lose as efficiency gains are generally pocketed by the industries. From an aggregate welfare standpoint, concentration is found to be beneficial in nearly 70% of the cases, mostly for low and moderate levels of concentration being partic...

  2. CHEMICAL EVOLUTION

    Energy Technology Data Exchange (ETDEWEB)

    Calvin, Melvin

    1965-06-01

    How did life come to be on the surface of the earth? Darwin himself recognized that his basic idea of evolution by variation and natural selection must be a continuous process extending backward in time through that period in which the first living things arose and into the period of 'Chemical Evolution' which preceded it. We are approaching the examination of these events by two routes. One is to seek for evidence in the ancient rocks of the earth which were laid down prior to that time in which organisms capable of leaving their skeletons in the rocks to be fossilized were in existence. This period is sometime prior to approximately 600 million years ago. The earth is believed to have taken its present form approximately 4700 million years ago. We have found in rocks whose age is about 1000 million years certain organic molecules which are closely related to the green pigment of plants, chlorophyll. This seems to establish that green plants were already fluorishing prior to that time. We have now found in rocks of still greater age, namely, 2500 million years, the same kinds of molecules mentioned above which can be attributed to the presence of living organisms. If these molecules are as old as the rocks, we have thus shortened the time available for the generation of the complex biosynthetic sequences which give rise to these specific hydrocarbons (polyisoprenoids) to less than 2000 million years.

  3. Chemical information science coverage in Chemical Abstracts.

    Science.gov (United States)

    Wiggins, G

    1987-02-01

    For many years Chemical Abstracts has included in its coverage publications on chemical documentation or chemical information science. Although the bulk of those publications can be found in section 20 of Chemical Abstracts, many relevant articles were found scattered among 39 other sections of CA in 1984-1985. In addition to the scattering of references in CA, the comprehensiveness of Chemical Abstracts as a secondary source for chemical information science is called into question. Data are provided on the journals that contributed the most references on chemical information science and on the languages of publication of relevant articles.

  4. Potential Impacts of Spilled Hydraulic Fracturing Fluid Chemicals on Water Resources: Types, volumes, and physical-chemical properties of chemicals

    Science.gov (United States)

    Hydraulic fracturing (HF) fluid chemicals spilled on-site may impact drinking water resources. While chemicals generally make up <2% of the total injected fluid composition by mass, spills may have undiluted concentrations. HF fluids typically consist of a mixture of base flui...

  5. Electrodialysis for the concentration of ethanolamine salts

    NARCIS (Netherlands)

    Groot, de Matheus T.; Bos, Ardina A.C.M.; Peris Lazaro, Alicia; Rooij, de Ralph M.; Bargeman, Gerrald

    2011-01-01

    Monoethanolamine (MEA) is currently produced from oil-based chemicals in an energy intensive process. Fermentative MEA production from renewable sources is considered to be a more sustainable process option. In such a process MEA is likely to be produced in a relatively low concentration in protonat

  6. Nature's chemicals and synthetic chemicals: comparative toxicology.

    OpenAIRE

    Ames, B N; Profet, M; Gold, L S

    1990-01-01

    The toxicology of synthetic chemicals is compared to that of natural chemicals, which represent the vast bulk of the chemicals to which humans are exposed. It is argued that animals have a broad array of inducible general defenses to combat the changing array of toxic chemicals in plant food (nature's pesticides) and that these defenses are effective against both natural and synthetic toxins. Synthetic toxins such as dioxin are compared to natural chemicals, such as indole carbinol (in brocco...

  7. Parameterizing cloud condensation nuclei concentrations during HOPE

    Science.gov (United States)

    Hande, Luke B.; Engler, Christa; Hoose, Corinna; Tegen, Ina

    2016-09-01

    An aerosol model was used to simulate the generation and transport of aerosols over Germany during the HD(CP)2 Observational Prototype Experiment (HOPE) field campaign of 2013. The aerosol number concentrations and size distributions were evaluated against observations, which shows satisfactory agreement in the magnitude and temporal variability of the main aerosol contributors to cloud condensation nuclei (CCN) concentrations. From the modelled aerosol number concentrations, number concentrations of CCN were calculated as a function of vertical velocity using a comprehensive aerosol activation scheme which takes into account the influence of aerosol chemical and physical properties on CCN formation. There is a large amount of spatial variability in aerosol concentrations; however the resulting CCN concentrations vary significantly less over the domain. Temporal variability is large in both aerosols and CCN. A parameterization of the CCN number concentrations is developed for use in models. The technique involves defining a number of best fit functions to capture the dependence of CCN on vertical velocity at different pressure levels. In this way, aerosol chemical and physical properties as well as thermodynamic conditions are taken into account in the new CCN parameterization. A comparison between the parameterization and the CCN estimates from the model data shows excellent agreement. This parameterization may be used in other regions and time periods with a similar aerosol load; furthermore, the technique demonstrated here may be employed in regions dominated by different aerosol species.

  8. Características físico-químicas e sensoriais da carne de cordeiros terminados com dietas contendo cana-de-açúcar ou silagem de milho e dois níveis de concentrado Physic-chemical and sensorial characteristics of meat from lambs finished with diets containing sugar cane or corn silage and two levels of concentrate

    Directory of Open Access Journals (Sweden)

    André Gustavo Leão

    2012-05-01

    Full Text Available Com o objetivo de avaliar as características físico-químicas e sensoriais da carne de cordeiros terminados em confinamento com dietas contendo cana-de-açúcar ou silagem de milho em duas relações volumoso:concentrado, 60:40 ou 40:60, utilizaram-se 32 cordeiros Ile de France, não-castrados, com 15 kg de peso corporal. Os animais foram confinados em baias individuais e abatidos aos 32 kg. As dietas e os músculos estudados não influenciaram o pH aos 45 minutos (6,56 e 24 horas (5,62 após o abate nem a capacidade de retenção de água (58,38% e a perda de peso por cocção (34,04%. A cor da carne e da gordura subcutânea não diferiu entre as dietas, entretanto a cor da carne variou entre os músculos longissimus lumborum e triceps brachii. A força de cisalhamento (1,85 kgf/cm² não foi afetada pelas dietas, porém diferiu entre os músculos, com valores de 1,41 e 2,28 kgf/cm² para o longissimus lumborum e triceps brachii, respectivamente. Nas análises sensoriais do lombo e da paleta, foram obtidas para os cordeiros alimentados com cana-de-açúcar e maior quantidade de concentrado as maiores notas para sabor (8,07 e 8,26, textura (8,53 e 8,53, preferência (8,20 e 8,46 e aceitação (8,33 e 8,26, respectivamente. A cana-de-açúcar na alimentação de cordeiros em confinamento manteve a qualidade físicoquímica da carne, podendo ser utilizada nesta fase de produção e, quando associada a maior quantidade de concentrado na dieta, melhora a qualidade sensorial da carne de cordeiros.With the objective of evaluating physic-chemical and sensorial characteristics of meat from lambs finished in feedlot with diets containing sugar cane or corn silage at two roughage:concentrate ratios, 60:40 or 40:60, 32 non-castrated Ile de France lambs, with 15 kg body weight were used. Animals were confined in individual stalls and were slaughtered at 32 kg body weight. Studied diets and muscles did not affect pH at 45 minutes (6.56 and 24 hours (5

  9. Fungitoxicity of chemical analogs with heartwood toxins.

    Science.gov (United States)

    Grohs, B M; Kunz, B

    1998-07-01

    Trans-stilbene and tropolone as chemical analogs with naturally occurring fungitoxic heartwood compounds were studied with respect to their fungitoxic potency. While stilbene showed no fungitoxic activity towards the fungi Aureobasidium pullulans var. melanogenum, Penicillium glabrum, and Trichoderma harzianum in the concentrations tested, the minimal inhibiting concentration of tropolone was 10(-3) M for Penicillium glabrum and Trichoderma harzianum, and 10(-5) M for Aureobasidium pullulans var. melanogenum. In all cases, the effect of tropolone was a fungistatic one. Using chemical analogs for assessing the chemical basis of the fungitoxicity of tropolone, this substance proved to be the only compound tested which possesses fungitoxic properties.

  10. Chemical analysis of aquatic pheromones in fish.

    Science.gov (United States)

    Stewart, Michael; Baker, Cindy F; Sorensen, Peter W

    2013-01-01

    Pheromones are chemicals that pass between members of the same species that have inherent meaning. In the case of fish, pheromones are water-soluble and found in low concentrations. As such, sensitive and selective methods are needed to separate and analyze these pheromones from an environmental matrix that may contain many other chemicals. This chapter describes a generic method used to concentrate and identify these chemicals and two extremely sensitive and selective methods for analysis, namely, mass spectrometry and enzyme-linked immunosorbent assay.

  11. Tehran Groundwater Chemical Pollution

    Directory of Open Access Journals (Sweden)

    M- Shariatpanahi

    1990-06-01

    Full Text Available Seventy eight wells water sample of Tehran plain were examined to determine r its groundwaters chemical pollution. Tehran s groundwaters are slightly acidic and their total dissolved solids are high and are in the hard water category."nThe nitrate concentration of wells water of west region is less than per¬missible level of W.H.O. standard, whereas, the nitrate concentration of some of the other regions wells exceed W.H.O. standard which is indication of pollution"nwith municipal wastewaters. The concentration of toxic elements Cr, Cd, As, Hg and"ni Pb of some of the west, east and south regions wells of Tehran is more than per¬missible level of W.H.O. standard, whereas, the concentration of Cu, Zn,Mn and detergents is below W.H.O. standard."n1"nIn general, the amount of dissolved materials of Tehran s groundwaters and also"ni the potential of their contamination with nitrate is increased as Tehran s ground-"nwaters move further to the south, and even though, Tehran s groundwaters contamination with toxic elements is limited to the industrial west district, industrial-residential east and south districts, but»with regard to the disposal methods of"nt municipal and industrial wastewaters, if Tehran s groundwaters pollution continues,"nlocal contamination of groundwaters is likely to spread. So that finally their quality changes in such a way that this water source may become unfit for most domestic, industrial and agricultural uses. This survey shows the necessity of collection and treatment of Tehran s wastewaters and Prevention of the disposal of untreated wastewaters into the environment.

  12. Generation of tunable and pulsatile concentration gradients via microfluidic network

    KAUST Repository

    Zhou, Bingpu

    2014-06-04

    We demonstrate a compact Polydimethylsiloxane microfluidic chip which can quickly generate ten different chemical concentrations simultaneously. The concentration magnitude of each branch can be flexibly regulated based on the flow rate ratios of the two injecting streams. The temporal/pulsatile concentration gradients are achieved by integrating on-chip pneumatic actuated valves controlled by the external signals. The temporal concentration gradients can also be tuned precisely by varying applied frequency and duty cycle of the trigger signal. It is believed that such microdevice will be potentially used for some application areas of producing stable chemical gradients as well as allowing fast, pulsatile gradient transformation in seconds.

  13. Chemical simulation of greywater.

    Science.gov (United States)

    Abed, Suhail Najem; Scholz, Miklas

    2016-01-01

    Sustainable water resources management attracts considerable attention in today's world. Recycling and reuse of both wastewater and greywater are becoming more attractive. The strategy is to protect ecosystem services by balancing the withdrawal of water and the disposal of wastewater. In the present study, a timely and novel synthetic greywater composition has been proposed with respect to the composition of heavy metals, nutrients and organic matter. The change in water quality of the synthetic greywater due to increasing storage time was monitored to evaluate the stability of the proposed chemical formula. The new greywater is prepared artificially using analytical-grade chemicals to simulate either low (LC) or high (HC) pollutant concentrations. The characteristics of the synthetic greywater were tested (just before starting the experiment, after two days and a week of storage under real weather conditions) and compared to those reported for real greywater. Test results for both synthetic greywater types showed great similarities with the physiochemical properties of published findings concerning real greywater. Furthermore, the synthetic greywater is relatively stable in terms of its characteristics for different storage periods. However, there was a significant (p greywater after two days of storage with reductions of 62% and 55%, respectively. A significant (p greywater after seven days of storage.

  14. Chemical Implementation of Finite-State Machines

    Science.gov (United States)

    Hjelmfelt, Allen; Weinberger, Edward D.; Ross, John

    1992-01-01

    With methods developed in a prior article on the chemical kinetic implementation of a McCulloch-Pitts neuron, connections among neurons, logic gates, and a clocking mechanism, we construct examples of clocked finite-state machines. These machines include a binary decoder, a binary adder, and a stack memory. An example of the operation of the binary adder is given, and the chemical concentrations corresponding to the state of each chemical neuron are followed in time. Using these methods, we can, in principle, construct a universal Turing machine, and these chemical networks inherit the halting problem

  15. Linking algal growth inhibition to chemical activity

    DEFF Research Database (Denmark)

    Schmidt, Stine N.; Mayer, Philipp

    to chemical activity, as opposed to e.g. the total concentration. Baseline toxicity (narcosis) for neutral hydrophobic organic compounds has been shown to initiate in the narrow chemical activity range of 0.01 to 0.1. This presentation focuses on linking algal growth inhibition to chemical activity....... High-quality toxicity data are carefully selected from peer-reviewed scientific literature and QSAR databases. This presentation shows how the chemical activity concept can be used to compare and combine toxicity data across compounds and species in order to characterize toxicity – and further how...

  16. Concentration of Hydrogen Peroxide

    Science.gov (United States)

    Parrish, Clyde F. (Inventor)

    2006-01-01

    Methods for concentrating hydrogen peroxide solutions have been described. The methods utilize a polymeric membrane separating a hydrogen peroxide solution from a sweep gas or permeate. The membrane is selective to the permeability of water over the permeability of hydrogen peroxide, thereby facilitating the concentration of the hydrogen peroxide solution through the transport of water through the membrane to the permeate. By utilizing methods in accordance with the invention, hydrogen peroxide solutions of up to 85% by volume or higher may be generated at a point of use without storing substantial quantities of the highly concentrated solutions and without requiring temperatures that would produce explosive mixtures of hydrogen peroxide vapors.

  17. Concentrating photovoltaic solar panel

    Science.gov (United States)

    Cashion, Steven A; Bowser, Michael R; Farrelly, Mark B; Hines, Braden E; Holmes, Howard C; Johnson, Jr., Richard L; Russell, Richard J; Turk, Michael F

    2014-04-15

    The present invention relates to photovoltaic power systems, photovoltaic concentrator modules, and related methods. In particular, the present invention features concentrator modules having interior points of attachment for an articulating mechanism and/or an articulating mechanism that has a unique arrangement of chassis members so as to isolate bending, etc. from being transferred among the chassis members. The present invention also features adjustable solar panel mounting features and/or mounting features with two or more degrees of freedom. The present invention also features a mechanical fastener for secondary optics in a concentrator module.

  18. Study on the variation of arsenic concentration in groundwater and chemical characteristics of arsenic in sediment cores at the areas with endemic arsenic poison disease in Jianghan Plain%江汉平原地方性砷中毒病区地下水砷含量变化及沉积物砷化学特征研究

    Institute of Scientific and Technical Information of China (English)

    周素华; 叶恒朋; 李明健; 熊培生; 杜冬云; 王靖文

    2015-01-01

    目的 了解江汉平原地方性砷中毒(地砷病)病区地下水砷含量变化,探讨该区域高砷水赋存环境、地下水系统砷的来源.方法 在湖北省仙桃市和洪湖市分别以地砷病患者家为中心点,在3km半径内各采集30份地下水样品和3个地质钻孔沉积物样芯;水砷含量比较采用配对t检验或配对符号秩和检验进行分析.结果 仙桃市南洪村2011-2012年水砷浓度低于2006-2007年(t=4.645 3,P<0.000 1),洪湖市姚河村2011-2012年水砷浓度高于2006-2007年(S=-150,P<0.000 1);高砷水呈弱酸、弱氧化性,水砷浓度与水样C1-、HCO3-、Fe、Mn浓度正相关,与水样SO42-、NO3-浓度负相关;研究区沉积物中砷浓度为1.500~ 17.289mg/kg,砷含量最大值均出现在泥土层,最小值均出现在沙层.结论 江汉平原地砷病病区高砷水砷含量的时空间变化程度较大,与中国山西大同盆地、山阴地区、内蒙古河套平原等原生高砷水地区有明显差异,为典型的高砷水赋存环境;研究区沉积物样品中砷含量与岩性结构有密切关系.%Objective To understand the variation of arsenic concentration in underground water at the endemic arsenic poison disease area of Jianghan Plain so as to better understand the spatial distribution of high arsenic groundwater,hydro-chemical evolution and source of arsenic in this region.Methods Thirty underground water samples were collected respectively around 3 km radius of the two houses where arsenic poisoning patients lived,in Xiantao and Honghu.Sediment cores of three drillings were collected as well.Both paired t-test or paired Wilcoxon Signed Ranking Test were used to compare the arsenic concentration of water.Results The arsenic concentration in 2011-2012 appeared lower than that in 2006-2007 at the Nanhong village of Xiantao (t=4.645 3,P<0.000 1),but was higher(S=-150,P<0.000 1) in the Yaohe village of Honghu.The pH value showed weak acidity with Eh as weak oxidated

  19. 柠檬酸浓度对化学浴沉积硫化铟薄膜形成机理的影响研究%Effect of Concentration of Citric Acid on the Formation Mechanism of In2S3 Thin Film by Chemical Bath Deposition

    Institute of Scientific and Technical Information of China (English)

    高志华; 刘晶冰; 汪浩

    2011-01-01

    以柠檬酸为配位剂,在酸性条件下采用化学浴沉积方法在FTO玻璃衬底上制得硫化铟薄膜,分别采用XRD、SEM、UV等手段对薄膜相结构、形貌和薄膜的透光率进行了表征.结果表明薄膜为立方结构的β-InS3,薄膜均一连续,呈网状表面形貌,透光率随厚度增加而递减,带隙宽度介于2.5~2.6 eV之间.主要研究了配位剂的浓度对薄膜形成机理的影响,结果表明:柠檬酸浓度较低时,柠檬酸根与铟离子的配位平衡是整个反应的速控步骤;当柠檬酸浓度较高时,硫代乙酰胺与酸作用生成硫离子的反应是整个反应的速控步骤.%A series of IN2S3 thin films were obtained via chemical bath deposition method on the FTO glass in the acidic solution, with citric acid as the complexing agent. XRD, SEM, UV were adopted to characterize phase structure, morphology and optical transmission of the thin films. The results indicated that all the thin films were cube structured β-In2S3, with uniform, network-like morphology. Transmission of films was step-down with the thickness of films increasing. Band gaps were calculated between 2.5 and 2.6 Ev. The effect of concentration of the complexing agent on the thin films formation mechanism was investigated. The results showed that when the concentration of citric acid was lower, control step of the whole reaction system was the complexation balance of citric acid ions and metal indium ions, and when higher, the key reaction was that thioacetamide decomposed to form sulfide ion under acidic condition.

  20. Chemical characterization of Brazilian hulless barley varieties, flour fractionation, and protein concentration Caracterização química de variedades brasileiras de cevada nua, fracionamento da farinha e concentração de proteína

    Directory of Open Access Journals (Sweden)

    Cristiane Vieira Helm

    2004-12-01

    Full Text Available Even though hulless barley is widely known due to its nutritional potential, in Brazil it is only grown at a few agricultural experimental stations. There is no published data about the chemical composition of Brazilian hulless barley varieties; however, research laboratories have studied their agronomical characteristics. The objectives of this study were to present the chemical characterization and effect of flour fractionation on protein concentration of six Brazilian hulless barley varieties, namely IAC IBON 214/82, IAC 8612/421, IAC 8501/31, IAC 8501/12, IAPAR 39-Acumaí, and IAC 8501/22. The analyses included: ash, ether extract, total protein, starch, total insoluble and soluble dietary fiber, and beta-glucans. Flour fractionation was carried out by sieving. The flour fractions were evaluated for crude protein, protein, and protein and non-protein nitrogen. Chemical composition varied (P Apesar de a cevada nua ser amplamente conhecida por seu potencial nutricional, no Brasil é apenas cultivada em poucas estações experimentais agronômicas. Em relação as variedades brasileiras de cevada nua, não se têm dados sobre a composição química, entretanto instituições de pesquisa têm estudado suas características agronômicas. Os objetivos deste estudo foram apresentar a caracterização química e o efeito no fracionamento da farinha obtida visando à concentração de proteína de seis variedades brasileiras de cevada nua: IAC IBON 214/82, IAC 8612/421, IAC 8501/31, IAC 8501/12, IAPAR 39-Acumaí, e IAC 8501/22. Foram realizadas análises de: cinzas, extrato etéreo, proteína total, amido, fibra alimentar total, solúvel e insolúvel e beta-glucanas. As frações das farinhas foram obtidas por peneiramento e avaliadas quanto aos teores de proteína bruta, proteína, nitrogênio protéico e não protéico. Houve variação entre as variedades testadas (P < 0,05. As variedades IAC 8501/22, IAC 8501/31 e IAC 8501/12 apresentaram o

  1. Pollutant concentrations in placenta

    DEFF Research Database (Denmark)

    Leino, O.; Kiviranta, H.; Karjalainen, A. K.;

    2013-01-01

    information for conducting contaminant risk assessments for the prenatal period. Out of the 117 individual persistent organic pollutants or metals assayed, 46 could be detected in more than half of the placentas. Moreover, dichlorodiphenyldichloroethylene (p,p'-DDE) was found in all placentas. The data...... congeners of persistent organic pollutants, seven organotin compounds, five heavy metals, and methylmercury in 130 randomly selected placentas. Additionally, we examined similarities between pollutant concentrations by analyzing correlations between their placental concentrations. Our results yield new...

  2. Chemical Security Analysis Center

    Data.gov (United States)

    Federal Laboratory Consortium — In 2006, by Presidential Directive, DHS established the Chemical Security Analysis Center (CSAC) to identify and assess chemical threats and vulnerabilities in the...

  3. Wide-Area Chemical Sensor

    Science.gov (United States)

    2014-11-01

    2014www.ll.mit.edu The detection and localization of gas releases such as methane from leaking natural gas pipelines or nitrogen oxides from failing electrical...reference gas cells, such as methane buffered by nitro- gen, and a low-concentration gas cell that contains the target species to calibrate the...self-referencing technique employed by WACS is particularly suited to detecting chemical agents composed of primarily small molecules— methane , various

  4. Interpreting serum risperidone concentrations.

    Science.gov (United States)

    Boerth, Joel M; Caley, Charles F; Goethe, John W

    2005-02-01

    Risperidone is an atypical antipsychotic commonly used for treatment of schizophrenia and other psychotic disorders. Although therapeutic drug monitoring is not routine for any of the atypical antipsychotics, serum antipsychotic concentrations are measured routinely to assess treatment nonadherence. In humans, risperidone is metabolized by cytochrome P450 2D6 to 9-hydroxyrisperidone; together these constitute the active moiety. Dose-proportional increases in serum concentrations have not been reported for the parent drug, but have been reported for 9-hydroxyrisperidone and the active moiety (i.e., the combined concentrations of risperidone and 9-hydroxyrisperidone). We describe a 34-year-old Caucasian man of Sicilian descent with a history of schizophrenia, disorganized type. He was suspected to be noncompliant with his risperidone therapy. Initially, active moiety risperidone concentrations increased linearly with prescribed dosage increases. However, with continued increases, active moiety concentrations adjusted downward and remained 17-36% below anticipated levels. We propose a method for estimating target active moiety concentrations of risperidone based on dosage-a method that may be used to guide clinicians in assessing nonadherence to risperidone treatment.

  5. The complex chemical Langevin equation.

    Science.gov (United States)

    Schnoerr, David; Sanguinetti, Guido; Grima, Ramon

    2014-07-14

    The chemical Langevin equation (CLE) is a popular simulation method to probe the stochastic dynamics of chemical systems. The CLE's main disadvantage is its break down in finite time due to the problem of evaluating square roots of negative quantities whenever the molecule numbers become sufficiently small. We show that this issue is not a numerical integration problem, rather in many systems it is intrinsic to all representations of the CLE. Various methods of correcting the CLE have been proposed which avoid its break down. We show that these methods introduce undesirable artefacts in the CLE's predictions. In particular, for unimolecular systems, these correction methods lead to CLE predictions for the mean concentrations and variance of fluctuations which disagree with those of the chemical master equation. We show that, by extending the domain of the CLE to complex space, break down is eliminated, and the CLE's accuracy for unimolecular systems is restored. Although the molecule numbers are generally complex, we show that the "complex CLE" predicts real-valued quantities for the mean concentrations, the moments of intrinsic noise, power spectra, and first passage times, hence admitting a physical interpretation. It is also shown to provide a more accurate approximation of the chemical master equation of simple biochemical circuits involving bimolecular reactions than the various corrected forms of the real-valued CLE, the linear-noise approximation and a commonly used two moment-closure approximation.

  6. Chemical Sensing for Buried Landmines - Fundamental Processes Influencing Trace Chemical Detection

    Energy Technology Data Exchange (ETDEWEB)

    PHELAN, JAMES M.

    2002-05-01

    Mine detection dogs have a demonstrated capability to locate hidden objects by trace chemical detection. Because of this capability, demining activities frequently employ mine detection dogs to locate individual buried landmines or for area reduction. The conditions appropriate for use of mine detection dogs are only beginning to emerge through diligent research that combines dog selection/training, the environmental conditions that impact landmine signature chemical vapors, and vapor sensing performance capability and reliability. This report seeks to address the fundamental soil-chemical interactions, driven by local weather history, that influence the availability of chemical for trace chemical detection. The processes evaluated include: landmine chemical emissions to the soil, chemical distribution in soils, chemical degradation in soils, and weather and chemical transport in soils. Simulation modeling is presented as a method to evaluate the complex interdependencies among these various processes and to establish conditions appropriate for trace chemical detection. Results from chemical analyses on soil samples obtained adjacent to landmines are presented and demonstrate the ultra-trace nature of these residues. Lastly, initial measurements of the vapor sensing performance of mine detection dogs demonstrates the extreme sensitivity of dogs in sensing landmine signature chemicals; however, reliability at these ultra-trace vapor concentrations still needs to be determined. Through this compilation, additional work is suggested that will fill in data gaps to improve the utility of trace chemical detection.

  7. An all-inorganic polyoxometalate–polyoxocation chemical garden

    OpenAIRE

    Points, Laurie J.; Cooper, Geoffrey J.T.; Dolbecq, Anne; Mialane, Pierre; Cronin, Leroy

    2016-01-01

    Herein, we show it is possible to produce wholly inorganic chemical gardens from a cationic polyoxometalate (POM) seed in an anionic POM solution, demonstrating a wholly POM-based chemical garden system that produces architectures over a wide concentration range. Six concentration dependent growth regimes have been discovered and characterized: clouds, membranes, slugs, tubes, jetting and budding.

  8. An all-inorganic polyoxometalate-polyoxocation chemical garden.

    Science.gov (United States)

    Points, Laurie J; Cooper, Geoffrey J T; Dolbecq, Anne; Mialane, Pierre; Cronin, Leroy

    2016-01-31

    Herein, we show it is possible to produce wholly inorganic chemical gardens from a cationic polyoxometalate (POM) seed in an anionic POM solution, demonstrating a wholly POM-based chemical garden system that produces architectures over a wide concentration range. Six concentration dependent growth regimes have been discovered and characterized: clouds, membranes, slugs, tubes, jetting and budding.

  9. Toxic chemical considerations for tank farm releases

    Energy Technology Data Exchange (ETDEWEB)

    Van Keuren, J.C.; Davis, J.S., Westinghouse Hanford

    1996-08-01

    This topical report contains technical information used to determine the accident consequences of releases of toxic chemical and gases for the Tank Farm Final Safety Analysis report (FSAR).It does not provide results for specific accident scenarios but does provide information for use in those calculations including chemicals to be considered, chemical concentrations, chemical limits and a method of summing the fractional contributions of each chemical. Tank farm composites evaluated were liquids and solids for double shell tanks, single shell tanks, all solids,all liquids, headspace gases, and 241-C-106 solids. Emergency response planning guidelines (ERPGs) were used as the limits.Where ERPGs were not available for the chemicals of interest, surrogate ERPGs were developed. Revision 2 includes updated sample data, an executive summary, and some editorial revisions.

  10. Photovoltaic solar concentrator

    Energy Technology Data Exchange (ETDEWEB)

    Nielson, Gregory N.; Gupta, Vipin P.; Okandan, Murat; Watts, Michael R.

    2016-03-15

    A photovoltaic solar concentrator is disclosed with one or more transverse-junction solar cells (also termed point contact solar cells) and a lens located above each solar cell to concentrate sunlight onto the solar cell to generate electricity. Piezoelectric actuators tilt or translate each lens to track the sun using a feedback-control circuit which senses the electricity generated by one or more of the solar cells. The piezoelectric actuators can be coupled through a displacement-multiplier linkage to provide an increased range of movement of each lens. Each lens in the solar concentrator can be supported on a frame (also termed a tilt plate) having three legs, with the movement of the legs being controlled by the piezoelectric actuators.

  11. Thermal cloak-concentrator

    Science.gov (United States)

    Shen, Xiangying; Li, Ying; Jiang, Chaoran; Ni, Yushan; Huang, Jiping

    2016-07-01

    For macroscopically manipulating heat flow at will, thermal metamaterials have opened a practical way, which possesses a single function, such as either cloaking or concentrating the flow of heat even though environmental temperature varies. By developing a theory of transformation heat transfer for multiple functions, here we introduce the concept of intelligent thermal metamaterials with a dual function, which is in contrast to the existing thermal metamaterials with single functions. By assembling homogeneous isotropic materials and shape-memory alloys, we experimentally fabricate a kind of intelligent thermal metamaterials, which can automatically change from a cloak (or concentrator) to a concentrator (or cloak) when the environmental temperature changes. This work paves an efficient way for a controllable gradient of heat, and also provides guidance both for arbitrarily manipulating the flow of heat and for efficiently designing similar intelligent metamaterials in other fields.

  12. Photovoltaic solar concentrator

    Energy Technology Data Exchange (ETDEWEB)

    Nielson, Gregory N.; Okandan, Murat; Resnick, Paul J.; Cruz-Campa, Jose Luis

    2012-12-11

    A photovoltaic solar concentrator is disclosed with one or more transverse-junction solar cells (also termed point contact solar cells) and a lens located above each solar cell to concentrate sunlight onto the solar cell to generate electricity. Piezoelectric actuators tilt or translate each lens to track the sun using a feedback-control circuit which senses the electricity generated by one or more of the solar cells. The piezoelectric actuators can be coupled through a displacement-multiplier linkage to provide an increased range of movement of each lens. Each lens in the solar concentrator can be supported on a frame (also termed a tilt plate) having three legs, with the movement of the legs being controlled by the piezoelectric actuators.

  13. Vacancy Concentration in Ice

    DEFF Research Database (Denmark)

    Mogensen, O. E.; Eldrup, Morten Mostgaard

    1977-01-01

    Based on the diffusion constant for self-diffusion in ice, which is believed to take place by a vacancy mechanism, we estimate the relative vacancy concentration near the melting point to be at least ∼ 10−6, i.e. much higher than previous estimates of about 10−10.......Based on the diffusion constant for self-diffusion in ice, which is believed to take place by a vacancy mechanism, we estimate the relative vacancy concentration near the melting point to be at least ∼ 10−6, i.e. much higher than previous estimates of about 10−10....

  14. Concentrated loads on concrete

    DEFF Research Database (Denmark)

    Lorenzen, Karen Grøndahl; Nielsen, Mogens Peter

    1997-01-01

    This report deals with concentrated loads on concrete.A new upper bound solution in the axisymmetrical case of a point load in the center of the end face of a cylinder is developed.Based on previous work dealing with failure mechanisms and upper bound solutions, new approximate formulas are devel......This report deals with concentrated loads on concrete.A new upper bound solution in the axisymmetrical case of a point load in the center of the end face of a cylinder is developed.Based on previous work dealing with failure mechanisms and upper bound solutions, new approximate formulas...

  15. The chemical life(1).

    Science.gov (United States)

    Hodges, Nathan

    2015-01-01

    You write this narrative autoethnography to open up a conversation about our chemical lives. You go through your day with chemical mindfulness, questioning taken-for-granted ideas about natural and artificial, healthy and unhealthy, dependency and addiction, trying to understand the chemical messages we consume through the experiences of everyday life. You reflect on how messages about chemicals influence and structure our lives and why some chemicals are celebrated and some are condemned. Using a second-person narrative voice, you show how the personal is relational and the chemical is cultural. You write because you seek a connection, a chemical bond.

  16. Solar concentrator/absorber

    Science.gov (United States)

    Von Tiesenhausen, G. F.

    1976-01-01

    Collector/energy converter, consisting of dual-slope optical concentrator and counterflow thermal energy absorber, is attached to multiaxis support structure. Efficient over wide range of illumination levels, device may be used to generate high temperature steam, serve as solar powered dryer, or power absorption cycle cooler.

  17. Drowning in concentrated syrup.

    Science.gov (United States)

    Talwar, Vandana; Sood, Nishant; Verma, P K

    2009-04-01

    Drowning is one of the two leading causes of accidental death in children. Most of the cases can be attributed to fresh or salt water drowning. We report an unusual case of acute respiratory distress syndrome in a one year old child following drowning in concentrated sugar syrup, in whom timely intervention and early supportive therapy resulted in a favorable outcome.

  18. Theory of Concentrated Vortices

    DEFF Research Database (Denmark)

    Alekseenko, Sergey; Kuibin, Pavel; Okulov, Valery

    This book presents comprehensive and authoritative coverage of the wide field of concentrated vortices observed in nature and technique. The methods for research of their kinematics and dynamics are considered. Special attention is paid to the flows with helical symmetry. The authors have describ...

  19. Chemical experiment through the microscope. II. ; Chemical garden. Kenbikyo wo shiyoshita kagaku jikken. II. ; Chemical garden

    Energy Technology Data Exchange (ETDEWEB)

    Ninomiya, A.

    1991-06-10

    This report describes the result of observation on chemical garden through the microscope. After putting some 2-3ml sodium silicate solution with fixed concentration into a cistern made of acrylic, various kinds of metallic salt with crystal size smaller than 2mm are added. The cistern is then placed on the stage of the microscope at an angle of 30{degree} to investigate buds growing from crystals of metallic salt specimens. Adopted concentrations of sodium silicate solution are 5%, 20%, and 50%. As a result, at the tips of growing buds, active motions of buds and increase of silicate in each kind of metal as reactive product are observed. In general, silicate concentration in the same metal increases conspicuously with lower concentration of sodium silicate solution. Moreover, it can be considered that the reason why chemical garden can be observed is not only because of difference in water pressure but also an important factor, the thickness of membranes at the tips of buds. 6 refs., 12 figs.

  20. Scattering Solar Thermal Concentrators

    Energy Technology Data Exchange (ETDEWEB)

    Giebink, Noel C. [Pennsylvania State Univ., State College, PA (United States)

    2015-01-31

    This program set out to explore a scattering-based approach to concentrate sunlight with the aim of improving collector field reliability and of eliminating wind loading and gross mechanical movement through the use of a stationary collection optic. The approach is based on scattering sunlight from the focal point of a fixed collection optic into the confined modes of a sliding planar waveguide, where it is transported to stationary tubular heat transfer elements located at the edges. Optical design for the first stage of solar concentration, which entails focusing sunlight within a plane over a wide range of incidence angles (>120 degree full field of view) at fixed tilt, led to the development of a new, folded-path collection optic that dramatically out-performs the current state-of-the-art in scattering concentration. Rigorous optical simulation and experimental testing of this collection optic have validated its performance. In the course of this work, we also identified an opportunity for concentrating photovoltaics involving the use of high efficiency microcells made in collaboration with partners at the University of Illinois. This opportunity exploited the same collection optic design as used for the scattering solar thermal concentrator and was therefore pursued in parallel. This system was experimentally demonstrated to achieve >200x optical concentration with >70% optical efficiency over a full day by tracking with <1 cm of lateral movement at fixed latitude tilt. The entire scattering concentrator waveguide optical system has been simulated, tested, and assembled at small scale to verify ray tracing models. These models were subsequently used to predict the full system optical performance at larger, deployment scale ranging up to >1 meter aperture width. Simulations at an aperture widths less than approximately 0.5 m with geometric gains ~100x predict an overall optical efficiency in the range 60-70% for angles up to 50 degrees from normal. However, the

  1. Maximum work configurations of finite potential capacity reservoir chemical engines

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    An isothermal endoreversible chemical engine operating between the finite potential capacity high-chemical-potential reservoir and the infinite potential capacity low-chemical-potential reservoir has been studied in this work.Optimal control theory was applied to determine the optimal cycle configurations corresponding to the maximum work output per cycle for the fixed total cycle time and a universal mass transfer law.Analyses of special examples showed that the optimal cycle configuration with the mass transfer law g∝△μ,where△μis the chemical potential difference,is an isothermal endoreversible chemical engine cycle,in which the chemical potential(or the concentration) of the key component in the working substance of low-chemical-potential side is a constant,while the chemical potentials(or the concentrations) of the key component in the finite potential capacity high-chemical-potential reservoir and the corresponding side working substance change nonlinearly with time,and the difference of the chemical potentials(or the ratio of the concentrations) of the key component between the high-chemical-potential reservoir and the working substance is a constant.While the optimal cycle configuration with the mass transfer law g∝△μc,where △μc is the concentration difference,is different from that with the mass transfer law g∝△μ significantly.When the high-chemical-potential reservoir is also an infinite potential capacity chemical potential reservoir,the optimal cycle configuration of the isothermal endoreversible chemical engine consists of two constant chemical potential branches and two instantaneous constant mass-flux branches,which is independent of the mass transfer law.The object studied in this paper is general,and the results can provide some guidelines for optimal design and operation of real chemical engines.

  2. Chemical face peels.

    Science.gov (United States)

    Matarasso, S L; Glogau, R G

    1991-01-01

    occlusion but also by employing different solutions as well as different concentrations of the same solution and skin preparation. Selection of the appropriate technique relies on critical analysis of the skin defect one wishes to treat balanced against the risks of treatment. The final protocol should be individualized for the needs of each patient. Despite heightened public awareness of the harmful effects of ultraviolet radiation, actinically damaged skin is no longer a problem restricted to an older-patient population. Fueled by the lay press and practitioners, there is a growing patient demand for chemical peels. Chemical peels alone or combined with ancillary aesthetic procedures can provide a dramatic improvement in facial appearance. The potential for improved cosmesis is not without inherent risk, however.(ABSTRACT TRUNCATED AT 400 WORDS)

  3. Existing chemicals: international activities.

    Science.gov (United States)

    Purchase, J F

    1989-01-01

    The standards of care used in the protection of the health and safety of people exposed to chemicals has increased dramatically in the last decade. Standards imposed by regulation and those adopted by industry have required a greater level of knowledge about the hazards of chemicals. In the E.E.C., the 6th amendment of the dangerous substances directive imposed the requirement that al new chemicals should be tested according to prescribed programme before introduction on to the market. The development of a European inventory of existing chemicals was an integral part of the 6th amendment. It has now become clear that increased standards of care referred to above must be applied to the chemicals on the inventory list. There is, however, a considerable amount of activity already under way in various international agencies. The OECD Chemicals Programme has been involved in considering the problem of existing chemicals for some time, and is producing a priority list and action programme. The International Programme on Chemical Safety produces international chemical safety cards, health and safety guides and environmental health criteria documents. The international register of potentially toxic compounds (part of UNEP) has prepared chemical data profiles on 990 compounds. The International Agency for Research on Cancer prepared monographs on the carcinogenic risk of chemicals to man. So far 42 volumes have been prepared covering about 900 substances. IARC and IPCS also prepare periodic reports on ongoing research on carcinogenicity or toxicity (respectively) of chemicals. The chemical industry through ECETOC (the European Chemical Industry Ecology and Toxicology Centre) has mounted a major initiative on existing chemicals. Comprehensive reviews of the toxicity of selected chemicals are published (Joint Assessment of Commodity Chemicals). In its technical report no. 30 ECETOC lists reviews and evaluations by major national and international organisations, which provides

  4. Concentric Split Flow Filter

    Science.gov (United States)

    Stapleton, Thomas J. (Inventor)

    2015-01-01

    A concentric split flow filter may be configured to remove odor and/or bacteria from pumped air used to collect urine and fecal waste products. For instance, filter may be designed to effectively fill the volume that was previously considered wasted surrounding the transport tube of a waste management system. The concentric split flow filter may be configured to split the air flow, with substantially half of the air flow to be treated traveling through a first bed of filter media and substantially the other half of the air flow to be treated traveling through the second bed of filter media. This split flow design reduces the air velocity by 50%. In this way, the pressure drop of filter may be reduced by as much as a factor of 4 as compare to the conventional design.

  5. Electrolyte Concentrates Treat Dehydration

    Science.gov (United States)

    2009-01-01

    Wellness Brands Inc. of Boulder, Colorado, exclusively licensed a unique electrolyte concentrate formula developed by Ames Research Center to treat and prevent dehydration in astronauts returning to Earth. Marketed as The Right Stuff, the company's NASA-derived formula is an ideal measure for athletes looking to combat dehydration and boost performance. Wellness Brands also plans to expand with products that make use of the formula's effective hydration properties to help treat conditions including heat stroke, altitude sickness, jet lag, and disease.

  6. Advances in chemical physics

    CERN Document Server

    Rice, Stuart A

    2012-01-01

    The Advances in Chemical Physics series-the cutting edge of research in chemical physics The Advances in Chemical Physics series provides the chemical physics field with a forum for critical, authoritative evaluations of advances in every area of the discipline. Filled with cutting-edge research reported in a cohesive manner not found elsewhere in the literature, each volume of the Advances in Chemical Physics series serves as the perfect supplement to any advanced graduate class devoted to the study of chemical physics. This volume explores: Quantum Dynamical Resonances in Ch

  7. Advanced millimeter wave chemical sensor.

    Energy Technology Data Exchange (ETDEWEB)

    Gopalsami, N.

    1999-03-24

    This paper discusses the development of an advanced millimeter-wave (mm-wave) chemical sensor and its applications for environmental monitoring and arms control treaty verification. The purpose of this work is to investigate the use of fingerprint-type molecular rotational signatures in the mm-wave spectrum to sense airborne chemicals. The mm-wave spectrum to sense airborne chemicals. The mm-wave sensor, operating in the frequency range of 220-300 GHz, can work under all weather conditions and in smoky and dusty environments. The basic configuration of the mm-wave sensor is a monostatic swept-frequency radar consisting of a mm-wave sweeper, a hot-electron-bolometer or Schottky barrier detector, and a trihedral reflector. The chemical plume to be detected is situated between the transmitter/detector and the reflector. Millimeter-wave absorption spectra of chemicals in the plume are determined by measuring the swept-frequency radar return signals with and without the plume in the beam path. The problem of pressure broadening, which hampered open-path spectroscopy in the past, has been mitigated in this work by designing a fast sweeping source over a broad frequency range. The heart of the system is a Russian backward-wave oscillator (BWO) tube that can be tuned over 220-350 GHz. Using the Russian BWO tube, a mm-wave radar system was built and field-tested at the DOE Nevada Test Site at a standoff distance of 60 m. The mm-wave system detected chemical plumes very well; the detection sensitivity for polar molecules like methyl chloride was down to a concentration of 12 ppm.

  8. Urinary bisphenol A concentrations in pregnant women.

    Science.gov (United States)

    Callan, Anna Carita; Hinwood, Andrea Lee; Heffernan, Amy; Eaglesham, Geoff; Mueller, Jochen; Odland, Jon Øyvind

    2013-11-01

    Bisphenol A is a chemical that is present in a number of products and types of food packaging. Prenatal exposure to bisphenol A may cause behavioural changes in young children. The aim of this study was to investigate exposure to bisphenol A in pregnant Australian women as a surrogate of neonatal exposure. First morning void urine samples were collected from 26 pregnant women at around week 38 of gestation. Bisphenol A was detectable in 85% of the samples analysed. The median concentration in this group of women was 2.41μg/L with a range of bisphenol A concentrations, as did women with a pre-pregnancy BMI of bisphenol A exposure in Australia and reveals that pregnant women have measured biological concentrations of urinary bisphenol A similar to those reported for pregnant women in other developed countries. Given the potential impacts of prenatal bisphenol A exposure, further research in this area is warranted.

  9. Effect of Chemicals on Chemical Mechanical Polishing of Glass Substrates

    Institute of Scientific and Technical Information of China (English)

    WANG Liang-Yong; ZHANG Kai-Liang; SONG Zhi-Tang; FENG Song-Lin

    2007-01-01

    @@ We investigate the effect of chemicals on chemical mechanical polishing (CMP) of glass substrates. Ceria slurry in an ultra-low concentration of 0.25wt.% is used and characterized by scanning electron microscopy. Three typical molecules, i.e. acetic acid, citric acid and sodium acrylic polymer, are adopted to investigate the effect on CMP performance in terms of material removal rate (MRR) and surface quality. The addition of sodium acrylic polymer shows the highest MRR as well as the best surface by atomic force microscopy after CMP, vhile the addition of citric acid shows the worst performance. These results reveal a mechanism that a long-chain molecule without any branches rather than small molecules and common molecules with ramose abundant-electron groups is better for the dispersion of the slurry and thus better for the CMP process.

  10. How accurate are the nonlinear chemical Fokker-Planck and chemical Langevin equations?

    Science.gov (United States)

    Grima, Ramon; Thomas, Philipp; Straube, Arthur V

    2011-08-28

    The chemical Fokker-Planck equation and the corresponding chemical Langevin equation are commonly used approximations of the chemical master equation. These equations are derived from an uncontrolled, second-order truncation of the Kramers-Moyal expansion of the chemical master equation and hence their accuracy remains to be clarified. We use the system-size expansion to show that chemical Fokker-Planck estimates of the mean concentrations and of the variance of the concentration fluctuations about the mean are accurate to order Ω(-3∕2) for reaction systems which do not obey detailed balance and at least accurate to order Ω(-2) for systems obeying detailed balance, where Ω is the characteristic size of the system. Hence, the chemical Fokker-Planck equation turns out to be more accurate than the linear-noise approximation of the chemical master equation (the linear Fokker-Planck equation) which leads to mean concentration estimates accurate to order Ω(-1∕2) and variance estimates accurate to order Ω(-3∕2). This higher accuracy is particularly conspicuous for chemical systems realized in small volumes such as biochemical reactions inside cells. A formula is also obtained for the approximate size of the relative errors in the concentration and variance predictions of the chemical Fokker-Planck equation, where the relative error is defined as the difference between the predictions of the chemical Fokker-Planck equation and the master equation divided by the prediction of the master equation. For dimerization and enzyme-catalyzed reactions, the errors are typically less than few percent even when the steady-state is characterized by merely few tens of molecules.

  11. Odor from a chemical perspective

    Energy Technology Data Exchange (ETDEWEB)

    Wray, T.K.

    1995-06-01

    Early odor-detection measurements categorized chemicals according to odor quality. Recent methods focus on the odor threshold, or the quantitative amount of a chemical in air that can be detected by the human sense of smell. Researchers characterize and quantify odor using an array of sensory and analytical procedures. Humans possess one of the dullest mammalian senses of smell; however, they can recognize about 10,000 distinct odors at concentrations ranging from less than 1 part per billion to several hundred thousand parts per million. Each time humans inhale, they chemically analyze microscopic pieces of the environment that make physical contact with the nerves in their noses. Individual molecules travel up the nose to a sheet of moist, mucus-bathed tissue that consists of about 5 million smell-sensing, olfactory neurons. After dissolving in the mucus, odor molecules ``float`` into appropriately shaped receptor pockets. A series of cellular reactions then transmit impulses to the limbic system, hippocampus and, finally, the neocortex. Odor detection is an important defense mechanism. The author presents the odor thresholds for selected organic compounds, and other hazardous chemicals.

  12. Chemical communication in bacteria

    Science.gov (United States)

    Suravajhala, Srinivasa Sandeep; Saini, Deepak; Nott, Prabhu

    Luminescence in Vibrio fischeri is a model for quorum-sensing-gene-regulation in bacteria. We study luminescence response of V. fischeri to both internal and external cues at the single cell and population level. Experiments with ES114, a wild-type strain, and ainS mutant show that luminescence induction in cultures is not always proportional to cell-density and there is always a basal level of luminescence. At any given concentration of the exogenously added signals, C6-HSL and C8-HSL, luminescence per cell reaches a maximum during the exponential phase and decreases thereafter. We hypothesize that (1) C6-HSL production and LuxR activity are not proportional to cell-density, and (2) there is a shift in equilibrium from C6-HSL to C8-HSL during the later stages of growth of the culture. RT-PCR analysis of luxI and luxR shows that the expression of these genes is maximum corresponding to the highest level of luminescence. The shift in equilibrium is shown by studying competitive binding of C6-HSL and C8-HSL to LuxR. We argue that luminescence is a unicellular behaviour, and an intensive property like per cell luminescence is more important than gross luminescence of the population in understanding response of bacteria to chemical signalling. Funding from the Department of Science and Technology, India is acknowledged.

  13. Solutions of the chemical kinetic equations for initially inhomogeneous mixtures.

    Science.gov (United States)

    Hilst, G. R.

    1973-01-01

    Following the recent discussions by O'Brien (1971) and Donaldson and Hilst (1972) of the effects of inhomogeneous mixing and turbulent diffusion on simple chemical reaction rates, the present report provides a more extensive analysis of when inhomogeneous mixing has a significant effect on chemical reaction rates. The analysis is then extended to the development of an approximate chemical sub-model which provides much improved predictions of chemical reaction rates over a wide range of inhomogeneities and pathological distributions of the concentrations of the reacting chemical species. In particular, the development of an approximate representation of the third-order correlations of the joint concentration fluctuations permits closure of the chemical sub-model at the level of the second-order moments of these fluctuations and the mean concentrations.

  14. Capacitive chemical sensor

    Science.gov (United States)

    Manginell, Ronald P; Moorman, Matthew W; Wheeler, David R

    2014-05-27

    A microfabricated capacitive chemical sensor can be used as an autonomous chemical sensor or as an analyte-sensitive chemical preconcentrator in a larger microanalytical system. The capacitive chemical sensor detects changes in sensing film dielectric properties, such as the dielectric constant, conductivity, or dimensionality. These changes result from the interaction of a target analyte with the sensing film. This capability provides a low-power, self-heating chemical sensor suitable for remote and unattended sensing applications. The capacitive chemical sensor also enables a smart, analyte-sensitive chemical preconcentrator. After sorption of the sample by the sensing film, the film can be rapidly heated to release the sample for further analysis. Therefore, the capacitive chemical sensor can optimize the sample collection time prior to release to enable the rapid and accurate analysis of analytes by a microanalytical system.

  15. Tobacco and chemicals (image)

    Science.gov (United States)

    Some of the chemicals associated with tobacco smoke include ammonia, carbon dioxide, carbon monoxide, propane, methane, acetone, hydrogen cyanide and various carcinogens. Other chemicals that are associated with chewing ...

  16. Chemical Industry Bandwidth Study

    Energy Technology Data Exchange (ETDEWEB)

    none,

    2006-12-01

    The Chemical Bandwidth Study provides a snapshot of potentially recoverable energy losses during chemical manufacturing. The advantage of this study is the use of "exergy" analysis as a tool for pinpointing inefficiencies.

  17. Chemical Search Web Utility

    Data.gov (United States)

    U.S. Environmental Protection Agency — The Chemical Search Web Utility is an intuitive web application that allows the public to easily find the chemical that they are interested in using, and which...

  18. Chemicals Industry Vision

    Energy Technology Data Exchange (ETDEWEB)

    none,

    1996-12-01

    Chemical industry leaders articulated a long-term vision for the industry, its markets, and its technology in the groundbreaking 1996 document Technology Vision 2020 - The U.S. Chemical Industry. (PDF 310 KB).

  19. Integration of chemical-specific exposure and pharmacokinetic information with the chemical-agnostic AOP framework to support high throughput risk assessment

    Science.gov (United States)

    Application of the Adverse Outcome Pathway (AOP) framework and high throughput toxicity testing in chemical-specific risk assessment requires reconciliation of chemical concentrations sufficient to trigger a molecular initiating event measured in vitro and at the relevant target ...

  20. Concentrated Solar Thermoelectric Power

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Gang [MIT; Ren, Zhifeng [University of Houston

    2015-07-09

    The goal of this project is to demonstrate in the lab that solar thermoelectric generators (STEGs) can exceed 10% solar-to-electricity efficiency, and STEGs can be integrated with phase-change materials (PCM) for thermal storage, providing operation beyond daylight hours. This project achieved significant progress in many tasks necessary to achieving the overall project goals. An accurate Themoelectric Generator (TEG) model was developed, which included realistic treatment of contact materials, contact resistances and radiative losses. In terms of fabricating physical TEGs, high performance contact materials for skutterudite TE segments were developed, along with brazing and soldering methods to assemble segmented TEGs. Accurate measurement systems for determining device performance (in addition to just TE material performance) were built for this project and used to characterize our TEGs. From the optical components’ side, a spectrally selective cermet surface was developed with high solar absorptance and low thermal emittance, with thermal stability at high temperature. A measurement technique was also developed to determine absorptance and total hemispherical emittance at high temperature, and was used to characterize the fabricated spectrally selective surfaces. In addition, a novel reflective cavity was designed to reduce radiative absorber losses and achieve high receiver efficiency at low concentration ratios. A prototype cavity demonstrated that large reductions in radiative losses were possible through this technique. For the overall concentrating STEG system, a number of devices were fabricated and tested in a custom built test platform to characterize their efficiency performance. Additionally, testing was performed with integration of PCM thermal storage, and the storage time of the lab scale system was evaluated. Our latest testing results showed a STEG efficiency of 9.6%, indicating promising potential for high performance concentrated STEGs.

  1. Censored correlated cytokine concentrations

    DEFF Research Database (Denmark)

    Andersen, Andreas; Benn, Christine Stabell; Jørgensen, Mathias J;

    2013-01-01

    Interest in cytokines as markers for the function of the immune system is increasing. Methods quantifying cytokine concentrations are often subject to detection limits, which lead to non-detectable observations and censored distributions. When distributions are skewed, geometric mean ratios (GMRs...... for both homogeneous and inhomogeneous normal distributions. For skewed mixture and heavy-tailed distributions, they perform reasonably well if censoring is less than 30%. We recommend these methods to estimate GMRRs. At least one of the methods is available in Stata, R or SAS....

  2. Chemical Physics Courses.

    Science.gov (United States)

    Lee, J.; Munn, R. W.

    1978-01-01

    This is a guide to the chemical physics major. The scope of chemical physics is presented, along with the general features of course contents and possible course structures. This information was derived from a survey of British universities and colleges offering undergraduate degree courses in chemical physics. (BB)

  3. Chemical Recycle of Plastics

    Directory of Open Access Journals (Sweden)

    Sara Fatima

    2014-11-01

    Full Text Available Various chemical processes currently prevalent in the chemical industry for plastics recycling have been discussed. Possible future scenarios in chemical recycling have also been discussed. Also analyzed are the effects on the environment, the risks, costs and benefits of PVC recycling. Also listed are the various types of plastics and which plastics are safe to use and which not after rcycle

  4. Chemicals for worldwide aquaculture

    Science.gov (United States)

    Schnick, R.A.

    1991-01-01

    Regulations and therapeutants or other safe chemicals that are approved or acceptable for use in the aquaculture industry in the US, Canada, Europe and Japan are presented, discussing also compounds that are unacceptable for aquaculture. Chemical use practices that could affect public health are considered and details given regarding efforts to increase the number of registered and acceptable chemicals.

  5. Benchmarking concentrating photovoltaic systems

    Science.gov (United States)

    Duerr, Fabian; Muthirayan, Buvaneshwari; Meuret, Youri; Thienpont, Hugo

    2010-08-01

    Integral to photovoltaics is the need to provide improved economic viability. To achieve this goal, photovoltaic technology has to be able to harness more light at less cost. A large variety of concentrating photovoltaic concepts has provided cause for pursuit. To obtain a detailed profitability analysis, a flexible evaluation is crucial for benchmarking the cost-performance of this variety of concentrating photovoltaic concepts. To save time and capital, a way to estimate the cost-performance of a complete solar energy system is to use computer aided modeling. In this work a benchmark tool is introduced based on a modular programming concept. The overall implementation is done in MATLAB whereas Advanced Systems Analysis Program (ASAP) is used for ray tracing calculations. This allows for a flexible and extendable structuring of all important modules, namely an advanced source modeling including time and local dependence, and an advanced optical system analysis of various optical designs to obtain an evaluation of the figure of merit. An important figure of merit: the energy yield for a given photovoltaic system at a geographical position over a specific period, can be calculated.

  6. Membrane distillation for milk concentration

    NARCIS (Netherlands)

    Moejes, S.N.; Romero Guzman, Maria; Hanemaaijer, J.H.; Barrera, K.H.; Feenstra, L.; Boxtel, van A.J.B.

    2015-01-01

    Membrane distillation is an emerging technology to concentrate liquid products while producing high quality water as permeate. Application for desalination has been studied extensively the past years, but membrane distillation has also potential to produce concentrated food products like concentrate

  7. Milho úmido, bagaço de cana e silagem de milho em dietas de alto teor de concentrado: 2. composição corporal e taxas de deposição dos tecidos High moisture corn, sugarcane bagasse and corn silage in high concentrate diets: 2. empty body chemical composition and tissues deposition rates

    Directory of Open Access Journals (Sweden)

    Alexandre Berndt

    2002-09-01

    245 kg were fed an adaptation diet for 33 days. After that period four animals were slaughtered to obtain initial body composition. The other 28 animals were allotted to the four treatments for a 124 days experimental feeding period. The experimental design was randomized blocks in 2 X 2 factorial arrangement (two roughage sources X two corn grain sources with seven replicates, testing the following treatments: corn silage+high moisture corn (Si-MU; corn silage+dry corn grain (Si-MS; sugarcane bagasse+high moisture corn (Ba-MU and sugarcane bagasse+dry corn grain (Ba-MS. There were no interactions between roughage and grain source for any variable evaluated. Corn silage was superior than sugarcane bagasse for daily empty body gain, and for deposition rates of all chemical components and energy. High moisture corn increased fat and energy content in the gain as well as the rate of lipid deposition. Data demonstrated that sugarcane bagasse is a poor roughage source in high concentrate diets when compared to whole plant corn silage. Results are also consistent with an increase in net energy content of ensiled corn grain.

  8. Advances in chemical physics

    CERN Document Server

    Rice, Stuart A

    2012-01-01

    The Advances in Chemical Physics series-the cutting edge of research in chemical physics The Advances in Chemical Physics series provides the chemical physics and physical chemistry fields with a forum for critical, authoritative evaluations of advances in every area of the discipline. Filled with cutting-edge research reported in a cohesive manner not found elsewhere in the literature, each volume of the Advances in Chemical Physics series presents contributions from internationally renowned chemists and serves as the perfect supplement to any advanced graduate class devoted to the study o

  9. Advances in chemical Physics

    CERN Document Server

    Rice, Stuart A

    2011-01-01

    The Advances in Chemical Physics series-the cutting edge of research in chemical physics The Advances in Chemical Physics series provides the chemical physics and physical chemistry fields with a forum for critical, authoritative evaluations of advances in every area of the discipline. Filled with cutting-edge research reported in a cohesive manner not found elsewhere in the literature, each volume of the Advances in Chemical Physics series offers contributions from internationally renowned chemists and serves as the perfect supplement to any advanced graduate class devoted to the study of che

  10. Advances in chemical physics

    CERN Document Server

    Rice, Stuart A

    2014-01-01

    Advances in Chemical Physics is the only series of volumes available that explores the cutting edge of research in chemical physics. This is the only series of volumes available that presents the cutting edge of research in chemical physics.Includes contributions from experts in this field of research.Contains a representative cross-section of research that questions established thinking on chemical solutions.Structured with an editorial framework that makes the book an excellent supplement to an advanced graduate class in physical chemistry or chemical physics.

  11. Advances in chemical physics

    CERN Document Server

    Rice, Stuart A

    2011-01-01

    The Advances in Chemical Physics series-the cutting edge of research in chemical physics The Advances in Chemical Physics series provides the chemical physics and physical chemistry fields with a forum for critical, authoritative evaluations of advances in every area of the discipline. Filled with cutting-edge research reported in a cohesive manner not found elsewhere in the literature, each volume of the Advances in Chemical Physics series offers contributions from internationally renowned chemists and serves as the perfect supplement to any advanced graduate class devoted to the study of che

  12. Stress concentration at notches

    CERN Document Server

    Savruk, Mykhaylo P

    2017-01-01

    This book compiles solutions of linear theory of elasticity problems for isotropic and anisotropic bodies with sharp and rounded notches. It contains an overview of established and recent achievements, and presents the authors’ original solutions in the field considered with extensive discussion. The volume demonstrates through numerous, useful examples the effectiveness of singular integral equations for obtaining exact solutions of boundary problems of the theory of elasticity for bodies with cracks and notches. Incorporating analytical and numerical solutions of the problems of stress concentrations in solid bodies with crack-like defects, this volume is ideal for scientists and PhD students dealing with the problems of theory of elasticity and fracture mechanics. Stands as a modern and extensive compendium of solutions to the problems of linear theory of elasticity of isotropic and anisotropic bodies with sharp and rounded notches; Adopts a highly reader-friendly layout of tables, charts, approximation ...

  13. Concentrating solar thermal power.

    Science.gov (United States)

    Müller-Steinhagen, Hans

    2013-08-13

    In addition to wind and photovoltaic power, concentrating solar thermal power (CSP) will make a major contribution to electricity provision from renewable energies. Drawing on almost 30 years of operational experience in the multi-megawatt range, CSP is now a proven technology with a reliable cost and performance record. In conjunction with thermal energy storage, electricity can be provided according to demand. To date, solar thermal power plants with a total capacity of 1.3 GW are in operation worldwide, with an additional 2.3 GW under construction and 31.7 GW in advanced planning stage. Depending on the concentration factors, temperatures up to 1000°C can be reached to produce saturated or superheated steam for steam turbine cycles or compressed hot gas for gas turbine cycles. The heat rejected from these thermodynamic cycles can be used for sea water desalination, process heat and centralized provision of chilled water. While electricity generation from CSP plants is still more expensive than from wind turbines or photovoltaic panels, its independence from fluctuations and daily variation of wind speed and solar radiation provides it with a higher value. To become competitive with mid-load electricity from conventional power plants within the next 10-15 years, mass production of components, increased plant size and planning/operating experience will be accompanied by technological innovations. On 30 October 2009, a number of major industrial companies joined forces to establish the so-called DESERTEC Industry Initiative, which aims at providing by 2050 15 per cent of European electricity from renewable energy sources in North Africa, while at the same time securing energy, water, income and employment for this region. Solar thermal power plants are in the heart of this concept.

  14. Use and Misuse of Chemical Reactivity Spreadsheets

    Energy Technology Data Exchange (ETDEWEB)

    Simmons, F

    2005-09-20

    Misidentifying chemical hazards can have serious deleterious effects. Consequences of not identifying a chemical are obvious and include fires, explosions, injury to workers, etc. Consequences of identifying hazards that are really not present can be equally as bad. Misidentifying hazards can result in increased work with loss of productivity, increased expenses, utilization/consumption of scarce resources, and the potential to modify the work to include chemicals or processes that are actually more hazardous than those originally proposed. For these reasons, accurate hazard identification is critical to any safety program. Hazard identification in the world of chemistry is, at best, a daunting task. The knowing or understanding, of the reactions between any of approximately twelve million known chemicals that may be hazardous, is the reason for this task being so arduous. Other variables, such as adding other reactants/contaminants or changing conditions (e.g., temperature, pressure, or concentration), make hazard determination something many would construe as being more than impossibly difficult. Despite these complexities, people who do not have an extensive background in the chemical sciences can be called upon to perform chemical hazard identification. Because hazard identification in the area of chemical safety is so burdensome and because people with a wide variety of training are called upon to perform this work, tools are required to aid in chemical hazard identification. Many tools have been developed. Unfortunately, many of these tools are not seen as the limited resource that they are and are used inappropriately.

  15. Control of Oxygen Concentration by Using a Carbonaceous Substance

    Directory of Open Access Journals (Sweden)

    Mohanad Jadan

    2005-01-01

    Full Text Available The control of oxygen concentration in gas flow may be used in chemical industry, heat power engineering, ecology, automobile construction and other industrial branches. This control is realized over a broad range of oxygen concentrations. The control of the oxygen concentration is based on passing of gas flow through a measuring cavity of radio spectrometer and measurement of a magnetic resonance signal. A change in the magnetic resonance signal of a dispersed carbonaceous substance, placed into the cavity, indicates to the changes in oxygen concentrations. The dispersed anthracite and thermal treatment cellulose substance in the oxygen-free medium are proposed to use as a carbonaceous substance.

  16. Summary of Dissolved Concentration Limits

    Energy Technology Data Exchange (ETDEWEB)

    Yueting Chen

    2001-06-11

    According to the Technical Work Plan titled Technical Work Plan for Waste Form Degradation Process Model Report for SR (CRWMS M&O 2000a), the purpose of this study is to perform abstractions on solubility limits of radioactive elements based on the process-level information and thermodynamic databases provided by Natural Environment Program Operations (NEPO) and Waste Package Operations (WPO). The scope of this analysis is to produce solubility limits as functions, distributions, or constants for all transported radioactive elements identified by the Performance Assessment Operations (PAO) radioisotope screening. Results from an expert elicitation for solubility limits of most radioactive elements were used in the previous Total System Performance Assessments (TSPAs). However, the elicitation conducted in 1993 does not meet the criteria set forth by the U.S. Nuclear Regulatory Commission (NRC) due to lack of documentation and traceability (Kotra et al. 1996, Section 3). Therefore, at the Waste Form Abstraction Workshop held on February 2-4, 1999, at Albuquerque, New Mexico, the Yucca Mountain Site Characterization Project (YMP) decided to develop geochemical models to study solubility for the proposed Monitored Geologic Repository. WPO/NEPO is to develop process-level solubility models, including review and compilation of relevant thermodynamic data. PAO's responsibility is to perform abstractions based on the process models and chemical conditions and to produce solubility distributions or response surfaces applicable to the proposed repository. The results of this analysis and conceptual model will feed the performance assessment for Total System Performance Assessment--Site Recommendation (TSPA-SR) and Total System Performance Assessment--License Application (TSPA-LA), and to the Waste Form Degradation Process Model Report section on concentration limits.

  17. Integrated optical sensors for the chemical domain

    NARCIS (Netherlands)

    Lambeck, Paul V.

    2006-01-01

    During the last decade there has been a rapidly growing interest in integrated optical (IO) sensors, expecially because many of them principally allow for sensitive, real time, label-free-on-site measurements of the concentration of (bio-)chemical species. This review aims at giving an overview of t

  18. Study of Endocrine Disrupting Chemicals in Environment

    Directory of Open Access Journals (Sweden)

    Zoltán Juvancz

    2008-06-01

    Full Text Available Endocrine disrupting chemicals (EDC cause more and more seriousenvironmental pollutions. The EDCs show only ng-μg/l concentration level in theenvironment, therefore their determinations require multistep sample preparationprocesses and highly sophisticated instrumentation. This paper discuss the EDC effects,and show examples for determination of such compounds.

  19. Exploring the planetary boundary for chemical pollution

    DEFF Research Database (Denmark)

    Diamond, Miriam L.; de Wit, Cynthia A.; Molander, Sverker;

    2015-01-01

    concentrations, exposures and adverse effects. As well, the normative nature of a PBCP presents challenges of negotiating pollution limits amongst societal groups with differing viewpoints. Thus, a combination of approaches is recommended as follows: develop indicators of chemical pollution, for both control...

  20. Substituição do grão de milho por polpa de citros em dietas com diferentes níveis de concentrado: 2. Taxas de deposição e composição química corporal Replacement of corn grain by citrus pulp in diets with different concentrate levels: 2. Deposition rates and body chemical composition

    Directory of Open Access Journals (Sweden)

    Paulo Roberto Leme

    2000-06-01

    Full Text Available Trinta e dois tourinhos da raça Santa Gertrudis com peso inicial de 230 kg e idade média de 9 meses foram utilizados em um experimento de abate comparativo com delineamento de blocos ao acaso em esquema fatorial 2 x 2, com dois níveis de concentrado na dieta, 20 ou 80%, e dois ingredientes energéticos no concentrado, milho ou polpa de citros peletizada. Quatro animais foram abatidos após o período de adaptação para determinação da composição corporal inicial do lote e os que receberam dietas com 80 e 20% de concentrado foram abatidos após 123 e 172 dias de confinamento, respectivamente. O tratamento com 80% de concentrado à base de milho resultou em ganhos de peso vazio de 1,038 kg/dia, 40% maior que os demais. A substituição do milho pela polpa de citros decresceu o ganho a níveis abaixo dos tratamentos com 20% de concentrado, nos quais não foi observada diferença entre as fontes de energia. A composição química corporal, estimada por intermédio da composição do corte da 9-10-11ª costelas com equações obtidas em outro grupo de animais Santa Gertrudis, não revelou diferenças entre os tratamentos.Thirty two Santa Gertrudis young bulls with an initial weight of 230 kg and 9 months of age were used in a comparative slaughter experiment with a 2 x 2 factorial arrangement with two concentrate levels, 80 and 20%, and two energetic ingredients in the concentrate, corn grain or pelletized citrus pulp. Four animals were slaughtered after the adaptation period for the determination of the initial body composition of lot and those that received diets with 80 and 20% of concentrate were slaughtered after 123 or 172 days, respectively. The treatment with 80% of corn grain based concentrate resulted in empty body weight gain of 1.038 kg/day, 40% greater than the others. The substitution of corn grain by citrus pulp decreased the body weight gain below those of the treatments with 20% concentrate, in which no difference due to

  1. Chemical Potential of Vacancies in Metal Crystals

    Institute of Scientific and Technical Information of China (English)

    SUN Jun; W.R.Tyson

    2000-01-01

    In this paper, a concept, the chemical potential of vacancies in metal crystals, has been derived from the partial mole free energy of vacancies based on a model of an atom-vacancy binary solution.For a pure metal crystal containing the mole concentration of vacancies, Cv and it's value in thermal equilibrium,C0, at temperature T the chemical potential can be expressed respectively as: μ v(Cv)=RT[1+1n(C√Co)]and μ v (Co)=RT The second term in μ v(Cv) is the chemical potential of the vacancies referred to the standardstate concentration given by J. P. Hirth [1] and first term is the standard-state one presented in this paper.

  2. Chemical bond fundamental aspects of chemical bonding

    CERN Document Server

    Frenking, Gernot

    2014-01-01

    This is the perfect complement to ""Chemical Bonding - Across the Periodic Table"" by the same editors, who are two of the top scientists working on this topic, each with extensive experience and important connections within the community. The resulting book is a unique overview of the different approaches used for describing a chemical bond, including molecular-orbital based, valence-bond based, ELF, AIM and density-functional based methods. It takes into account the many developments that have taken place in the field over the past few decades due to the rapid advances in quantum chemica

  3. How boundaries shape chemical delivery in microfluidics

    Science.gov (United States)

    Aminian, Manuchehr; Bernardi, Francesca; Camassa, Roberto; Harris, Daniel M.; McLaughlin, Richard M.

    2016-12-01

    Many microfluidic systems—including chemical reaction, sample analysis, separation, chemotaxis, and drug development and injection—require control and precision of solute transport. Although concentration levels are easily specified at injection, pressure-driven transport through channels is known to spread the initial distribution, resulting in reduced concentrations downstream. Here we document an unexpected phenomenon: The channel’s cross-sectional aspect ratio alone can control the shape of the concentration profile along the channel length. Thin channels (aspect ratio delivery, based only on the channel dimensions.

  4. Hand chemical burns.

    Science.gov (United States)

    Robinson, Elliot P; Chhabra, A Bobby

    2015-03-01

    There is a vast and ever-expanding variety of potentially harmful chemicals in the military, industrial, and domestic landscape. Chemical burns make up a small proportion of all skin burns, yet they can cause substantial morbidity and mortality. Additionally, the hand and upper extremity are the most frequently involved parts of the body in chemical burns, and therefore these injuries may lead to severe temporary or permanent loss of function. Despite this fact, discussion of the care of these injuries is sparse in the hand surgery literature. Although most chemical burns require only first response and wound care, some require the attention of a specialist for surgical debridement and, occasionally, skin coverage and reconstruction. Exposure to certain chemicals carries the risk of substantial systemic toxicity and even mortality. Understanding the difference between thermal and chemical burns, as well as special considerations for specific compounds, will improve patient treatment outcomes.

  5. Bioleaching of marmatite in high concentration of iron

    Institute of Scientific and Technical Information of China (English)

    邱冠周; 吴伯增; 覃文庆; 蓝卓越

    2002-01-01

    Bioleaching of marmatite with a culture of Thiobacillus ferrooxidans and Thiobacillus thiooxidans in high concentration of iron was studied, the results show that the zinc leaching rate of the mixed culture is faster than that of the sole Thiobacillus ferrooxidans, the increasing iron concentration in leaching solution enhances the zinc leaching rate. The SEM analysis indicates that the chemical leaching residues is covered with porous solid layer of elemental sulfur, while elemental sulfur is not found in the bacterial leaching residues. The primary role of bacteria in bioleaching of sphalerite is to oxidize the chemical leaching products of ferrous ion and elemental sulfur, thus the indirect mechanism prevails in the bioleaching of marmatite.

  6. Chemical Biology is.....

    OpenAIRE

    2007-01-01

    Chemical Biology is a relatively new field, and as such is not yet simply or succinctly defined. It includes such a wide range of fundamental problems that this commentary could only include just a few snapshots of potential areas of interest. Overarching themes and selected recent successes and ideas in chemical biology are described to illustrate broadly the scope of the field, but should not be taken as exhaustive. The Chemical Biology Section of Chemistry Central Journal is pleased to rec...

  7. Multivariate Quantitative Chemical Analysis

    Science.gov (United States)

    Kinchen, David G.; Capezza, Mary

    1995-01-01

    Technique of multivariate quantitative chemical analysis devised for use in determining relative proportions of two components mixed and sprayed together onto object to form thermally insulating foam. Potentially adaptable to other materials, especially in process-monitoring applications in which necessary to know and control critical properties of products via quantitative chemical analyses of products. In addition to chemical composition, also used to determine such physical properties as densities and strengths.

  8. Introduction to chemical kinetics

    CERN Document Server

    Soustelle, Michel

    2013-01-01

    This book is a progressive presentation of kinetics of the chemical reactions. It provides complete coverage of the domain of chemical kinetics, which is necessary for the various future users in the fields of Chemistry, Physical Chemistry, Materials Science, Chemical Engineering, Macromolecular Chemistry and Combustion. It will help them to understand the most sophisticated knowledge of their future job area. Over 15 chapters, this book present the fundamentals of chemical kinetics, its relations with reaction mechanisms and kinetic properties. Two chapters are then devoted to experimental re

  9. Laboratory of Chemical Physics

    Data.gov (United States)

    Federal Laboratory Consortium — Current research in the Laboratory of Chemical Physics is primarily concerned with experimental, theoretical, and computational problems in the structure, dynamics,...

  10. Chemical Processing Manual

    Science.gov (United States)

    Beyerle, F. J.

    1972-01-01

    Chemical processes presented in this document include cleaning, pickling, surface finishes, chemical milling, plating, dry film lubricants, and polishing. All types of chemical processes applicable to aluminum, for example, are to be found in the aluminum alloy section. There is a separate section for each category of metallic alloy plus a section for non-metals, such as plastics. The refractories, super-alloys and titanium, are prime candidates for the space shuttle, therefore, the chemical processes applicable to these alloys are contained in individual sections of this manual.

  11. Effect of membrane filtration artifacts on dissolved trace element concentrations

    Science.gov (United States)

    Horowitz, Arthur J.; Elrick, Kent A.; Colberg, Mark R.

    1992-01-01

    Among environment scientists, the current and almost universally accepted definition of dissolved constituents is an operational one; only those materials which pass through a 0.45-??m membrane filter are considered to be dissolved. Detailed laboratory and field studies on Fe and Al indicate that a number of factors associated with filtration, other than just pore size, can substantially alter 'dissolved' trace element concentrations; these include: filter type, filter diameter, filtration method, volume of sample processed, suspended sediment concentration, suspended sediment grain-size distribution, concentration of colloids and colloidally associated trace elements and concentration of organic matter. As such, reported filtered-water concentrations employing the same pore size filter may not be equal. Filtration artifacts may lead to the production of chemical data that indicate seasonal or annual 'dissolved' chemical trends which do not reflect actual environmental conditions. Further, the development of worldwide averages for various dissolved chemical constituents, the quantification of geochemical cycles, and the determination of short- or long-term environmental chemical trends may be subject to substantial errors, due to filtration artifacts, when data from the same or multiple sources are combined. Finally, filtration effects could have a substantial impact on various regulatory requirements.

  12. Influence of chemical elements on mammalian spermatozoa.

    Science.gov (United States)

    Marzec-Wróblewska, U; Kamiński, P; Lakota, P

    2012-01-01

    Exposure to heavy metals is the most important risk factor in the assessment of spermatogenesis. About 30-40 % cases of infertility are caused by the male factor, and most of them are due to the small quantity of spermatozoa or to inferior spermatozoa quality. The negative impact on sperm motility, morphology and concentration of such chemical elements as Al, Cr, Cd, Pb or Fe was observed, while positive influence was noticed for Zn, Mg, and Ca. The influence of Mn, Cu, Ni or Se on spermatozoa is ambiguous. Chemical elements known as necessary for capacitation and acrosome reaction are Zn, Mg and Ca, while Cd and Pb disturb initiation and progress of the acrosome reaction. The positive effect of chemical elements Al, Cd, Cr, Cu, Ni, Pb, Se, and Zn, lies in their protection against oxidative stress. On the other hand, Al, Cu and Ni induce structural changes in the testes and epididymis or influence interactions with other chemical elements.

  13. Treatment of biomass to obtain a target chemical

    Science.gov (United States)

    Dunson, Jr., James B.; Tucker, III, Melvin P.; Elander, Richard T.; Hennessey, Susan Marie

    2010-08-24

    Target chemicals were produced using biocatalysts that are able to ferment sugars derived from treated biomass. Sugars were obtained by pretreating biomass under conditions of high solids and low ammonia concentration, followed by saccharification.

  14. Polyfluorinated chemicals in European surface waters, ground- and drinking waters

    NARCIS (Netherlands)

    Eschauzier, C.; de Voogt, P.; Brauch, H.-J.; Lange, F.T.; Knepper, T.P.; Lange, F.T.

    2012-01-01

    Polyfluorinated chemicals (PFCs), especially short chain fluorinated alkyl sulfonates and carboxylates, are ubiquitously found in the environment. This chapter aims at giving an overview of PFC concentrations found in European surface, ground- and drinking waters and their behavior during convention

  15. Which chemicals drive biological effects in wastewater and recycled water?

    Science.gov (United States)

    Tang, Janet Y M; Busetti, Francesco; Charrois, Jeffrey W A; Escher, Beate I

    2014-09-01

    Removal of organic micropollutants from wastewater during secondary treatment followed by reverse osmosis and UV disinfection was evaluated by a combination of four in-vitro cell-based bioassays and chemical analysis of 299 organic compounds. Concentrations detected in recycled water were below the Australian Guidelines for Water Recycling. Thus the detected chemicals were considered not to pose any health risk. The detected pesticides in the wastewater treatment plant effluent and partially advanced treated water explained all observed effects on photosynthesis inhibition. In contrast, mixture toxicity experiments with designed mixtures containing all detected chemicals at their measured concentrations demonstrated that the known chemicals explained less than 3% of the observed cytotoxicity and less than 1% of the oxidative stress response. Pesticides followed by pharmaceuticals and personal care products dominated the observed mixture effects. The detected chemicals were not related to the observed genotoxicity. The large proportion of unknown toxicity calls for effect monitoring complementary to chemical monitoring.

  16. Sunflower meal concentrations in Massai grass silage

    Directory of Open Access Journals (Sweden)

    Máikal S. Borja

    2012-08-01

    Full Text Available Objetive. This experiment was conducted to evaluate the best sunflower meal concentration in Massai grass silage. Materials and methods. The treatments were composed of 0, 8, 16, and 24% sunflower meal (natural matter basis during ensiling of Massai grass, with four repetitions. Results. The regression equation showed that the inclusion of sunflower meal between 2.14% and 13.91% obtained a silage dry matter between 25 and 35%, which are the values recommended for the production of high quality silage. The addition of sunflower meal showed a linear increase in crude protein, reaching 18% DM with the highest concentration of sunflower meal. The highest feed value index was obtained with the addition of 24% sunflower meal in the silage. The estimated total digestible nutrient of silage increased linearly with sunflower meal concentration. The silage pH values had a quadratic effect, reaching the lowest value (4.1 with 15% sunflower meal addition. Conclusions. Based on the chemical composition and forage quality, a concentration of 14% sunflower meal should be used for high-quality silage with good nutritional value.

  17. Concentration of lemon pectin extract by ultrafiltration

    Directory of Open Access Journals (Sweden)

    Damián Stechina

    2012-09-01

    Full Text Available Current annual lemon production in Argentina is about 900 thousand t. 75% is used industrially to obtain pasteurized juice concentrate. Since 40 - 45 % of citrus fruit content is peel and seeds, the annual lemon residue yield is 360 thousand t. Lemon peel contains about 30% (B.S. of peptic substances with an important commercial value due to its gelling and thickening properties for food, chemical, pharmacological and cosmetic products. Membrane processes have many applications in food manufacture. The objective of this study is to analyze the influence of ultrafiltration operating variables on instant permeate flow (Fp and on the energy requirement for pectin extract concentration from lemon peel. A DDS lab module was used, lab 20-772 model with synthetic material membranes, 9 kDa, shear force, the intrinsic membrane resistance (Rm being 3*1013 m -1 . Results show that Fp decrease caused by polarization induced resistance occurrence and the influence of operating variables on Fp offer relevant data to estimate the energy requirement in relation to feeding flow at constant temperature, which may be compared to pectin concentration increase in the retained flow in relation to initial extract concentration.

  18. A thermodynamical framework for chemically reacting systems

    Science.gov (United States)

    Kannan, K.; Rajagopal, K. R.

    2011-04-01

    In this paper, we develop a thermodynamic framework that is capable of describing the response of viscoelastic materials that are undergoing chemical reactions that takes into account stoichiometry. Of course, as a special sub-case, we can also describe the response of elastic materials that undergo chemical reactions. The study generalizes the framework developed by Rajagopal and co-workers to study the response of a disparate class of bodies undergoing entropy producing processes. One of the quintessential feature of this framework is that the second law of thermodynamics is formulated by introducing Gibbs' potential, which is the natural way to study problems involving chemical reactions. The Gibbs potential-based formulation also naturally leads to implicit constitutive equations for the stress tensor. Another feature of the framework is that the constraints due to stoichiometry can also be taken into account in a consistent manner. The assumption of maximization of the rate of entropy production due to dissipation, heat conduction, and chemical reactions is invoked to determine an equation for the evolution of the natural configuration κ p( t)( B), the heat flux vector and a novel set of equations for the evolution of the concentration of the chemical constituents. To determine the efficacy of the framework with regard to chemical reactions, those occurring during vulcanization, a challenging set of chemical reactions, are chosen. More than one type of reaction mechanism is considered and the theoretically predicted distribution of mono, di and polysulfidic cross-links agree reasonably well with available experimental data.

  19. Study on Behavior of Carbon Reduction of Monazite Concentrate

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The behavior of monazite concentrate reduced by carbon, especially the decomposed procedure of rare earth phosphates, was investigated by X-ray diffraction , electron probe, TG method and chemical analysis. The results show that rare earth phosphates in monazite concentrate can be reduced to their oxides, among them the decomposition processes of cerium phosphate are not in step with lanthanum phosphate, neodymium phosphate and so on, and the phosphorus was volatilized into air in simple form.

  20. Current trends of the development of chemical analysis

    Directory of Open Access Journals (Sweden)

    Rema Matakova

    2014-12-01

    Full Text Available This paper presents dynamics of the development of all stages of chemical analysis during last 15 years. The ways of the quality improvement of chemical analysis and its considerable advancement into the field of trace concentrations of substances are shown. Features of development of analytical methods, modern techniques for concentration and separation of substances, as well as chemomerrical processing of results are analyzed. Huge importance of computerization and automation of the analysis is shown.

  1. Riparian zone controls on base cation concentrations in boreal streams

    Directory of Open Access Journals (Sweden)

    J. L. J. Ledesma

    2013-01-01

    Full Text Available Forest riparian zones are a major in control of surface water quality. Base cation (BC concentrations, fluxes, and cycling in the riparian zone merit attention because of increasing concern of negative consequences for re-acidification of surface waters from future climate and forest harvesting scenarios. We present a two-year study of BC and silica (Si flow-weighted concentrations from 13 riparian zones and 14 streams in a boreal catchment in northern Sweden. The Riparian Flow-Concentration Integration Model (RIM was used to estimate riparian zone flow-weighted concentrations and tested to predict the stream flow-weighted concentrations. Spatial variation in BC and Si concentrations as well as in flow-weighted concentrations was related to differences in Quaternary deposits, with the largest contribution from lower lying silty sediments and the lowest contribution from wetland areas higher up in the catchment. Temporal stability in the concentrations of most elements, a remarkably stable Mg / Ca ratio in the soil water and a homogeneous mineralogy suggest that the stable patterns found in the riparian zones are a result of distinct mineralogical upslope groundwater signals integrating the chemical signals of biological and chemical weathering. Stream water Mg / Ca ratio indicates that the signal is subsequently maintained in the streams. RIM gave good predictions of Ca, Mg, and Na flow-weighted concentrations in headwater streams. The difficulty in modelling K and Si suggests a stronger biogeochemical influence on these elements. The observed chemical dilution effect with flow in the streams was related to variation in groundwater levels and element concentration profiles in the riparian zones. This study provides a first step toward specific investigations of the vulnerability of riparian zones to changes induced by forest management or climate change, with focus on BC or other compounds.

  2. Formal modeling of a system of chemical reactions under uncertainty.

    Science.gov (United States)

    Ghosh, Krishnendu; Schlipf, John

    2014-10-01

    We describe a novel formalism representing a system of chemical reactions, with imprecise rates of reactions and concentrations of chemicals, and describe a model reduction method, pruning, based on the chemical properties. We present two algorithms, midpoint approximation and interval approximation, for construction of efficient model abstractions with uncertainty in data. We evaluate computational feasibility by posing queries in computation tree logic (CTL) on a prototype of extracellular-signal-regulated kinase (ERK) pathway.

  3. Chemical burn or reaction

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/article/000059.htm Chemical burn or reaction To use the sharing features on this page, please enable JavaScript. Chemicals that touch skin can lead to a reaction on the skin, throughout the body, or both. ...

  4. Chemical warfare in freshwater

    NARCIS (Netherlands)

    Mulderij, Gabi

    2006-01-01

    Aquatic macrophytes can excrete chemical substances into their enviroment and these compounds may inhibit the growth of phytoplankton. This process is defined as allelopathy: one organism has effects on another via the excretion of a (mixture of) chemical substance(s). With laboratory and field expe

  5. Chemical Reactivity Test (CRT)

    Energy Technology Data Exchange (ETDEWEB)

    Zaka, F. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2016-12-13

    The Chemical Reactivity Test (CRT) is used to determine the thermal stability of High Explosives (HEs) and chemical compatibility between (HEs) and alien materials. The CRT is one of the small-scale safety tests performed on HE at the High Explosives Applications Facility (HEAF).

  6. Biobased chemicals from polyhydroxybutyrate

    NARCIS (Netherlands)

    Spekreijse, Jurjen

    2016-01-01

    Currently, most chemicals and materials are obtained from fossil resources. After use, these chemicals and materials are converted to CO2. As discussed in chapter 1, this causes a build-up of CO2 in the atmosphere, the main driving force of global warming. In order to reach a sustai

  7. Conical electromagnetic radiation flux concentrator

    Science.gov (United States)

    Miller, E. R.

    1972-01-01

    Concentrator provides method of concentrating a beam of electromagnetic radiation into a smaller beam, presenting a higher flux density. Smaller beam may be made larger by sending radiation through the device in the reverse direction.

  8. Concentration of Swiss Elite Orienteers.

    Science.gov (United States)

    Seiler, Roland; Wetzel, Jorg

    1997-01-01

    A visual discrimination task was used to measure concentration among 43 members of Swiss national orienteering teams. Subjects were above average in the number of target objects dealt with and in duration of continuous concentration. For females only, ranking in orienteering performance was related to quality of concentration (ratio of correct to…

  9. Chemical basis of metabolic network organization.

    Directory of Open Access Journals (Sweden)

    Qiang Zhu

    2011-10-01

    Full Text Available Although the metabolic networks of the three domains of life consist of different constituents and metabolic pathways, they exhibit the same scale-free organization. This phenomenon has been hypothetically explained by preferential attachment principle that the new-recruited metabolites attach preferentially to those that are already well connected. However, since metabolites are usually small molecules and metabolic processes are basically chemical reactions, we speculate that the metabolic network organization may have a chemical basis. In this paper, chemoinformatic analyses on metabolic networks of Kyoto Encyclopedia of Genes and Genomes (KEGG, Escherichia coli and Saccharomyces cerevisiae were performed. It was found that there exist qualitative and quantitative correlations between network topology and chemical properties of metabolites. The metabolites with larger degrees of connectivity (hubs are of relatively stronger polarity. This suggests that metabolic networks are chemically organized to a certain extent, which was further elucidated in terms of high concentrations required by metabolic hubs to drive a variety of reactions. This finding not only provides a chemical explanation to the preferential attachment principle for metabolic network expansion, but also has important implications for metabolic network design and metabolite concentration prediction.

  10. Modeling heterogeneous chemical processes on aerosol surface

    Institute of Scientific and Technical Information of China (English)

    Junjun Deng; Tijian Wang; Li Liu; Fei Jiang

    2010-01-01

    To explore the possible impact of heterogeneous chemical processes on atmospheric trace components,a coupled box model including gas-phase chemical processes,aerosol thermodynamic equilibrium processes,and heterogeneous chemical processes on the surface of dust,black carbon(BC)and sea salt is set up to simulate the effects of heterogeneous chemistry on the aerosol surface,and analyze the primary factors affecting the heterogeneous processes.Results indicate that heterogeneous chemical processes on the aerosol surface in the atmosphere will affect the concentrations of trace gases such as H2O2,HO2,O3,NO2,NO3,HNO3 and SO2,and aerosols such as SO42-,NO3-and NH4+.Sensitivity tests suggest that the magnitude of the impact of heterogeneous processes strongly depends on aerosol concentration and the surface uptake coefficients used in the box model.However,the impact of temperature on heterogeneous chemical processes is considerably less.The"renoxification"of HNO3 will affect the components of the troposphere such as nitrogen oxide and ozone.

  11. High-efficiency solar concentrator

    Science.gov (United States)

    Lansing, F. L.; Dorman, J.

    1980-01-01

    A new type of solar concentrator is presented using liquid lenses and simple translational tracking mechanism. The concentrator achieves a 100:1 nominal concentration ratio and is compared in performance with a flat-plate collector having two sheets of glazing and non-selective coating. The results of the thermal analysis show that higher temperatures can be obtained with the concentrator than is possible with the non-concentrator flat-plate type. Furthermore, the thermal efficiency far exceeds that of the comparative flat-plate type for all operating conditions.

  12. Chemical and thermal unfolding of calreticulin

    DEFF Research Database (Denmark)

    Duus, K.; Larsen, N.; Tran, T. A. T.;

    2013-01-01

    was found to obtain a molten structure in urea concentrations between 1-1.5 M urea, and to unfold/aggregate at high and low pH values. The results demonstrated that the fluorescent dye binding assay could measure the thermal stability of calreticulin in aqueous buffers with results comparable to melting...... assay, we have investigated the chemical and thermal stability of calreticulin. When the chemical stability of calreticulin was assessed, a midpoint for calreticulin unfolding was calculated to 3.0M urea using CD data at 222 nm. Using the fluorescent dye binding thermal shift assay, calreticulin...

  13. Chemical ecology of fungi.

    Science.gov (United States)

    Spiteller, Peter

    2015-07-01

    Fungi are widespread in nature and have conquered nearly every ecological niche. Fungi occur not only in terrestrial but also in freshwater and marine environments. Moreover, fungi are known as a rich source of secondary metabolites. Despite these facts, the ecological role of many of these metabolites is still unknown and the chemical ecology of fungi has not been investigated systematically so far. This review intends to present examples of the various chemical interactions of fungi with other fungi, plants, bacteria and animals and to give an overview of the current knowledge of fungal chemical ecology.

  14. SEX-STEROID AND THYROID HORMONE CONCENTRATIONS IN JUVENILE ALLIGATORS (ALLIGATOR MISSISSIPPIENSIS) FROM CONTAMINATED AND REFERENCE LAKES IN FLORIDA, USA

    Science.gov (United States)

    Sex-steroid and thyroid hormones are critical regulators of growth and reproduction in all vertebrates, and several recent studies suggest that environmental chemicals can alter circulating concentrations of these hormones. This study examines plasma concentrations of estradiol-...

  15. Regional differences and sources of organochlorine pesticides in soils surrounding chemical industrial parks

    NARCIS (Netherlands)

    Wang, G.; Lu, Y.L.; Li, J.; Wang, T.Y.; Han, Jingyi; Luo, W.; Shi, Y.J.; Jiao, W.T.

    2009-01-01

    Concentrations of organochlorine pesticides (OCPs; dichlorodiphenyltrichloroethanes (DDTs), hexachlorocyclohexanes (HCHs), hexachlorobenzene (HCB)) were investigated in 105 soil samples collected in vicinity of the chemical industrial parks in Tianjin, China. OCP concentrations significantly varied

  16. Comparison of the radiological and chemical toxicity of lead

    Energy Technology Data Exchange (ETDEWEB)

    Beitel, G.A.; Mott, S.

    1995-03-01

    This report estimates the worst-case radiological dose to an individual from ingested lead containing picocurie levels of radionuclides and then compares the calculated radiological health effects to the chemical toxic effects from that same lead. This comparison provides an estimate of the consequences of inadvertently recycling, in the commercial market, lead containing nominally undetectable concentrations of radionuclides. Quantitative expressions for the radiological and chemical toxicities of lead are based on concentrations of lead in the blood stream. The result shows that the chemical toxicity of lead is a greater health hazard, by orders of magnitude, than any probable companion radiation dose.

  17. Study on scattering properties of tissues with hyperosmotic chemical agents

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Optical properties of biological tissue are variable due to the changes of micro-structures and scattering constituents after hyperosmotic chemical agents permeates into tissue. The changes of optical properties of biological tissue are due to the refractive indices matching between the scatterers with high refractive index and the ground substances, which reduce scattering of tissue. The main reasons are that permeated semipermeable chemical agents with higher refractive index than the ground substances of tissuemakes the refractive index of ground substances of tissue higher by the enhancement of the permeated concentration. We studied on the collimated transmittance changes of light penetrating biological tissue after the hyperosmotic chemical agents administrates with different concentration.

  18. Low concentrator PV optics optimization

    Science.gov (United States)

    Sharp, Leonard; Chang, Ben

    2008-08-01

    Purpose: Cost reduction is a major focus of the solar industry. Thin film technologies and concentration systems are viable ways to reducing cost, with unique strengths and weakness for both. Most of the concentrating PV work focuses on high concentration systems for reducing energy cost. Meanwhile, many believe that low concentrators provide significant cost reduction potential while addressing the mainstream PV market with a product that acts as a flat panel replacement. This paper analyzes the relative benefit of asymmetric vs. symmetric optics for low-concentrators in light of specific PV applications. Approach: Symmetric and asymmetric concentrating PV module performance is evaluated using computer simulation to determine potential value across various geographic locations and applications. The selected optic design is modeled against standard cSi flat panels and thin film to determine application fit, system level energy density and economic value. Results: While symmetric designs may seem ideal, asymmetric designs have an advantage in energy density. Both designs are assessed for aperture, optimum concentration ratio, and ideal system array configuration. Analysis of performance across climate specific effects (diffuse, direct and circumsolar) and location specific effects (sunpath) are also presented. The energy density and energy production of low concentrators provide a compelling value proposition. More significantly, the choice of optics for a low concentrating design can affect real world performance. With the goal of maximizing energy density and return on investment, this paper presents the advantages of asymmetric optic concentration and illustrates the value of this design within specific PV applications.

  19. Elements of chemical thermodynamics

    CERN Document Server

    Nash, Leonard K

    2005-01-01

    This survey of purely thermal data in calculating the position of equilibrium in a chemical reaction highlights the physical content of thermodynamics, as distinct from purely mathematical aspects. 1970 edition.

  20. Chemical Physics Summer School

    Energy Technology Data Exchange (ETDEWEB)

    None

    2002-06-28

    The Gordon Research Conference (GRC) on Chemical Physics Summer School was held at Roger Williams University, Bristol, RI. Emphasis was placed on current unpublished research and discussion of the future target areas in this field.

  1. Biotechnology for renewable chemicals

    DEFF Research Database (Denmark)

    Borodina, Irina; Kildegaard, Kanchana Rueksomtawin; Jensen, Niels Bjerg

    2014-01-01

    The majority of the industrial organic chemicals are derived from fossil sources. With the oil and gas resources becoming limiting, biotechnology offers a sustainable alternative for production ofchemicals from renewable feedstocks. Yeast is an attractive cell factory forsustainable production...

  2. Chemical Engineering at NASA

    Science.gov (United States)

    Collins, Jacob

    2008-01-01

    This viewgraph presentation is a review of the career paths for chemicals engineer at NASA (specifically NASA Johnson Space Center.) The author uses his personal experience and history as an example of the possible career options.

  3. Legendary Chemical Aphrodisiacs.

    Science.gov (United States)

    Waddell, Thomas G.; And Others

    1980-01-01

    Presents a survey of the literature and a summary of information regarding aphrodisiacs. Chemical compounds are discussed as groups of plant natural products, animal natural products, and synthetic products. (CS)

  4. Chemical evolution and life

    Directory of Open Access Journals (Sweden)

    Malaterre Christophe

    2015-01-01

    Full Text Available In research on the origins of life, the concept of “chemical evolution” aims at explaining the transition from non-living matter to living matter. There is however strong disagreement when it comes to defining this concept more precisely, and in particular with reference to a chemical form of Darwinian evolution: for some, chemical evolution is nothing but Darwinian evolution applied to chemical systems before life appeared; yet, for others, it is the type of evolution that happened before natural selection took place, the latter being the birthmark of living systems. In this contribution, I review the arguments defended by each side and show how both views presuppose a dichotomous definition of “life”.

  5. Chemical agent recoveries

    Data.gov (United States)

    U.S. Environmental Protection Agency — Dataset shows the calculation of reported decontamination efficacies from the raw data (i.e., measured amount of chemical recovered from test coupons and positive...

  6. 219-S chemical compatibility

    Energy Technology Data Exchange (ETDEWEB)

    GOODWIN, L.D.

    1999-08-31

    This document consists of tables of the materials that make up the ''wetted'' parts of the 219-S waste handling facility and a combination of manufacturer lists of chemicals that are not recommended.

  7. Chemical Data Access Tool

    Data.gov (United States)

    U.S. Environmental Protection Agency — This tool is intended to aid individuals interested in learning more about chemicals that are manufactured or imported into the United States. Health and safety...

  8. Chemicals from coal

    Energy Technology Data Exchange (ETDEWEB)

    Harold A. Wittcoff; Bryan G. Reuben; Jeffrey S. Plotkin

    2004-12-01

    This chapter contains sections titled: Chemicals from Coke Oven Distillate; The Fischer-Tropsch Reaction; Coal Hydrogenation; Substitute Natural Gas (SNG); Synthesis Gas Technology; Calcium Carbide; Coal and the Environment; and Notes and References

  9. A bionics chemical synapse.

    Science.gov (United States)

    Thanapitak, Surachoke; Toumazou, Christofer

    2013-06-01

    Implementation of the current mode CMOS circuit for chemical synapses (AMPA and NMDA receptors) with dynamic change of glutamate as the neurotransmitter input is presented in this paper. Additionally, circuit realisation for receptor GABA(A) and GABA(B) with an electrical signal which symbolises γ-Aminobutyric Acid (GABA) perturbation is introduced. The chemical sensor for glutamate sensing is the modified ISFET with enzyme (glutamate oxidase) immobilisation. The measured results from these biomimetics chemical synapse circuits closely match with the simulation result from the mathematical model. The total power consumption of the whole chip (four chemical synapse circuits and all auxiliary circuits) is 168.3 μW. The total chip area is 3 mm(2) in 0.35-μm AMS CMOS technology.

  10. Nanomotor dynamics in a chemically oscillating medium

    Energy Technology Data Exchange (ETDEWEB)

    Robertson, Bryan, E-mail: bryan.robertson@mail.utoronto.ca; Kapral, Raymond, E-mail: rkapral@chem.utoronto.ca [Chemical Physics Theory Group, Department of Chemistry, University of Toronto, Toronto, Ontario M5S 3H6 (Canada)

    2015-04-21

    Synthetic nanomotors powered by chemical reactions have potential uses as cargo transport vehicles in both in vivo and in vitro applications. In many situations, motors will have to operate in out-of-equilibrium complex chemically reacting media, which supply fuel to the motors and remove the products they produce. Using molecular simulation and mean-field theory, this paper describes some of the new features that arise when a chemically powered nanomotor, operating through a diffusiophoretic mechanism, moves in an environment that supports an oscillatory chemical reaction network. It is shown how oscillations in the concentrations in chemical species in the environment give rise to oscillatory motor dynamics. More importantly, since the catalytic reactions on the motor that are responsible for its propulsion couple to the bulk phase reaction network, the motor can change its local environment. This process can give rise to distinctive spatiotemporal structures in reaction-diffusion media that occur as a result of active motor motion. Such locally induced nonequilibrium structure will play an important role in applications that involve motor dynamics in complex chemical media.

  11. Nanomotor dynamics in a chemically oscillating medium

    Science.gov (United States)

    Robertson, Bryan; Kapral, Raymond

    2015-04-01

    Synthetic nanomotors powered by chemical reactions have potential uses as cargo transport vehicles in both in vivo and in vitro applications. In many situations, motors will have to operate in out-of-equilibrium complex chemically reacting media, which supply fuel to the motors and remove the products they produce. Using molecular simulation and mean-field theory, this paper describes some of the new features that arise when a chemically powered nanomotor, operating through a diffusiophoretic mechanism, moves in an environment that supports an oscillatory chemical reaction network. It is shown how oscillations in the concentrations in chemical species in the environment give rise to oscillatory motor dynamics. More importantly, since the catalytic reactions on the motor that are responsible for its propulsion couple to the bulk phase reaction network, the motor can change its local environment. This process can give rise to distinctive spatiotemporal structures in reaction-diffusion media that occur as a result of active motor motion. Such locally induced nonequilibrium structure will play an important role in applications that involve motor dynamics in complex chemical media.

  12. Standard chemical exergy of elements updated

    Energy Technology Data Exchange (ETDEWEB)

    Rivero, R. [Instituto Mexicano del Petroleo, Grupo de Exergia, Eje Central Lazaro Cardenas 152, 07730, Mexico, D.F. (Mexico)]. E-mail: rrivero@imp.mx; Garfias, M. [Instituto Mexicano del Petroleo, Grupo de Exergia, Eje Central Lazaro Cardenas 152, 07730, Mexico, D.F. (Mexico)

    2006-12-15

    The chemical exergy of a substance is the maximum work that can be obtained from it by taking it to chemical equilibrium with the reference environment at constant temperature and pressure. This exergy is normally taken or calculated from tabulated values obtained for standard conditions, i.e. an ambient temperature of 298.15 K, an atmospheric pressure of 1 atm, and a model of reference species which considers the concentration of the most common components of the atmosphere, the oceans and the Earth's crust. The model proposed by Szargut for the calculation of the standard chemical exergy of elements and organic and inorganic substances has been revised. As a result of this revision, updated values of standard chemical exergy of elements are presented and compared with the ones estimated by Szargut. Because of some anomalous behaviour in the chemical exergy when a different salinity of seawater is assumed, some different reference species than those used in the latest version of the Szargut model were proposed for the following elements: silver, gold, barium, calcium, cadmium, copper, mercury, magnesium, nickel, lead, strontium and zinc. A complete set of updated values of chemical exergies of elements for the standard conditions (298.15 K and 1 atm) is tabulated.

  13. Countermeasures to Hazardous Chemicals,

    Science.gov (United States)

    1989-04-01

    of any effective community awareness and emergency response program is an informed public familiar with the operations of local chemical plants. Such a...protection systems. 2. Booklel, ’Protecting People and the Environment.’ - A concise booklet developed to familiarize the public with chemical operations and...Jefe, Seccion de Estudios y Planificacion 102. Civil Defense Administation c/Evaristo San Miguel, 8 Ministry of Interior Madrid-8 Ankara ESPANA

  14. Computational Systems Chemical Biology

    OpenAIRE

    Oprea, Tudor I.; Elebeoba E. May; Leitão, Andrei; Tropsha, Alexander

    2011-01-01

    There is a critical need for improving the level of chemistry awareness in systems biology. The data and information related to modulation of genes and proteins by small molecules continue to accumulate at the same time as simulation tools in systems biology and whole body physiologically-based pharmacokinetics (PBPK) continue to evolve. We called this emerging area at the interface between chemical biology and systems biology systems chemical biology, SCB (Oprea et al., 2007).

  15. Sawmill chemicals and carcinogenesis.

    OpenAIRE

    Huff, J

    2001-01-01

    Workers in wood industries are exposed to variable medleys of chemicals, both natural and synthetic. Additional exposures include fungi, bacteria, bark and wood dusts, solvents, paints, and various other wood coatings. These individual and conglomerate exposures have been associated with diverse occupational illnesses and hazards, including cancers. In this commentary, I summarize both experimental and epidemiologic carcinogenesis results for several chemicals used in the wood industry, as we...

  16. Chemical Ionization Mass Spectrometry.

    Science.gov (United States)

    1980-01-30

    mass spectrometer. Also discussed were Corporation, St. Louis , Mo. unique analytical applications of several negative ion chemical Synthesis of the...were purchsed from obtained at a probe temperature of 180-200 °C and displays Sigma Chemical Co.. St. Louis , Mo. Arginine hydrochloride (4) a M4...13) Rosenstock. H, M.: Drax . K.: Stener. B. W: Hernon J. T. J. Phys. Chem, Ref. Data 1977, 6, Supl. 1. 774-783,167 occur in the ratio of 10/ 1

  17. Controlled Chemical Patterns with ThermoChemical NanoLithography (TCNL)

    Science.gov (United States)

    Carroll, Keith; Giordano, Anthony; Wang, Debin; Kodali, Vamsi; King, W. P.; Marder, S. R.; Riedo, E.; Curtis, J. E.

    2012-02-01

    Many research areas, both fundamental and applied, rely upon the ability to organize non-trivial assemblies of molecules on surfaces. In this work, we introduce a significant extension of ThermoChemical NanoLithography (TCNL), a high throughput chemical patterning technique that uses temperature-driven chemical reactions localized near the tip of a thermal cantilever. By combining a chemical kinetics based model with experiments, we have developed a protocol for varying the concentration of surface bound molecules. The result is an unprecedented ability to fabricate extremely complex patterns comprised of varying chemical concentrations, as demonstrated by sinusoidal patterns of amine groups with varying pitches (˜5-15 μm) and the replication of Leonardo da Vinci's Mona Lisa with dimensions of ˜30 x 40 μm^2. Programmed control of the chemical reaction rate should have widespread applications for a technique which has already been shown to nanopattern various substrates including graphene nanowires, piezoelectric crystals, and optoelectronic materials.

  18. Environmental/chemical thesaurus

    Energy Technology Data Exchange (ETDEWEB)

    Shriner, C.R.; Dailey, N.S.; Jordan, A.C.; Miller, K.C.; Owens, E.T.; Rickert, L.W.

    1978-06-01

    The Environmental/Chemical Thesaurus approaches scientific language control problems from a multidisciplinary view. The Environmental/Biomedical Terminology Index (EBTI) was used as a base for the present thesaurus. The Environmental/Chemical Thesaurus, funded by the Environmental Protection Agency, used as its source of new terms those major terms found in 13 Environmental Protection Agency data bases. The scope of this thesaurus includes not only environmental and biomedical sciences, but also the physical sciences with emphasis placed on chemistry. Specific chemical compounds are not included; only classes of chemicals are given. To adhere to this level of classification, drugs and pesticides are identified by class rather than by specific chemical name. An attempt was also made to expand the areas of sociology and economics. Terminology dealing with law, demography, and geography was expanded. Proper names of languages and races were excluded. Geographic terms were expanded to include proper names for oceans, continents, major lakes, rivers, and islands. Political divisions were added to allow for proper names of countries and states. With such a broad scope, terminology for specific sciences does not provide for indexing to the lowest levels in plant, animal, or chemical classifications.

  19. Computational systems chemical biology.

    Science.gov (United States)

    Oprea, Tudor I; May, Elebeoba E; Leitão, Andrei; Tropsha, Alexander

    2011-01-01

    There is a critical need for improving the level of chemistry awareness in systems biology. The data and information related to modulation of genes and proteins by small molecules continue to accumulate at the same time as simulation tools in systems biology and whole body physiologically based pharmacokinetics (PBPK) continue to evolve. We called this emerging area at the interface between chemical biology and systems biology systems chemical biology (SCB) (Nat Chem Biol 3: 447-450, 2007).The overarching goal of computational SCB is to develop tools for integrated chemical-biological data acquisition, filtering and processing, by taking into account relevant information related to interactions between proteins and small molecules, possible metabolic transformations of small molecules, as well as associated information related to genes, networks, small molecules, and, where applicable, mutants and variants of those proteins. There is yet an unmet need to develop an integrated in silico pharmacology/systems biology continuum that embeds drug-target-clinical outcome (DTCO) triplets, a capability that is vital to the future of chemical biology, pharmacology, and systems biology. Through the development of the SCB approach, scientists will be able to start addressing, in an integrated simulation environment, questions that make the best use of our ever-growing chemical and biological data repositories at the system-wide level. This chapter reviews some of the major research concepts and describes key components that constitute the emerging area of computational systems chemical biology.

  20. The Chemical Revolution revisited.

    Science.gov (United States)

    Chang, Hasok

    2015-02-01

    I respond to the critical comments by Martin Kusch and Ursula Klein on my account of the Chemical Revolution. I comment along three different lines: descriptive, explanatory, and normative. (1) I agree with Klein that Lavoisier did not introduce drastic changes in chemical ontology, but maintain that there was methodological incommensurability in the Chemical Revolution; in response to Kusch's view, I maintain that Lavoisier's victory was slow and incomplete. (2) Admitting that there were many causes shaping the outcome of the Chemical Revolution, including the convenience of Lavoisier's theoretical scheme and various complicated social factors, I still think that the general rise of compositionism was an important factor. (3) I defend my normative pluralist view on the Chemical Revolution, denying Kusch's argument that chemists had overwhelmingly good reasons to trust Lavoisier and his allies over the phlogistonists. Overall, I agree with Kusch that it would be desirable to have a good descriptive-normative sociological account of the Chemical Revolution, but I also think that it should be an account that allows for divergence in individuals' and sub-communities' self-determination.

  1. MARKET CONCENTRATION AND ECONOMIC PERFORMANCE

    Directory of Open Access Journals (Sweden)

    Sophia Nikolaevna Lyubyaschenko

    2013-10-01

    Full Text Available In this paper, we describe the trend of market concentration, the formation of strategic groups in Russian industry, principles of integration of firms in strategic groups, and the reasons for increase of market concentration. Purpose - to propose the methods of measuring industry concentration in terms of coordination.   Methodology: methods of system analysis, economic analysis, the methodological approaches of the theory of industrial organization, regression analysis.Results: Authors provide the methods of measuring industry concentration in terms of coordination. Authors established laws of formation of strategic groups (coalitions. The relationship between the concentration rate and business cycle sensitivity of firms in Russian industry was described.Practical implications: The methods of measuring industry concentration is of interest to economists, business strategists, and government agencies.DOI: http://dx.doi.org/10.12731/2218-7405-2013-7-36

  2. Market concentration and economic performance

    OpenAIRE

    Sophia Nikolaevna Lyubyaschenko; Valery Ivanovich Mamonov

    2013-01-01

    In this paper, we describe the trend of market concentration, the formation of strategic groups in Russian industry, principles of integration of firms in strategic groups, and the reasons for increase of market concentration. Purpose - to propose the methods of measuring industry concentration in terms of coordination.   Methodology: methods of system analysis, economic analysis, the methodological approaches of the theory of industrial organization, regression analysis.Results: Authors prov...

  3. Localization of chemical sources using e. coli chemotaxis

    Science.gov (United States)

    Davison, Timothy; Nguyen, Hoa; Nickels, Kevin; Frasch, Duncan; Basagaoglu, Hakan

    2016-04-01

    This paper furthers the application of chemotaxis to small-scale robots by simulating a system that localizes a chemical source in a dynamic fluid environment. This type of system responds to a chemical stimulus by mimicking, for example, the way that E. Coli bacteria move toward attractants (nutrients) and away from repellents. E. Coli use the intracellular signaling pathway to process the temporal change in the chemical concentration to determine if the cells should run or tumble. Previous work has shown that this process can be simulated with robots and used to localize chemical sources based upon a fixed nutrient gradient. Our work furthers this study by simulating the injection of an effluent of chemical at a specified location in an environment and uses computational fluid dynamics to model the interactions of the robot with the fluid while performing chemotaxis. The interactions between the chemical and fluid are also modelled with the advection diffusion equation to determine the concentration gradient. This method allows us to compute, over a lattice, the chemical concentration at all points and feed these results into an existing E. Coli controller for the robot, which results in the robot executing a tumble or a run according to a probabilistic formula. By simulating the robot in this complex environment, our work facilitates refinement of the chemotaxis controller while proving the ability of chemotactic robots to localize specific chemicals in environments that more closely resemble those encountered in the wide-ranging types of locations in which this robotic system might be deployed.

  4. Chemically driven fluid transport in long microchannels

    Science.gov (United States)

    Shen, Mingren; Ye, Fangfu; Liu, Rui; Chen, Ke; Yang, Mingcheng; Ripoll, Marisol

    2016-09-01

    Chemical gradients maintained along surfaces can drive fluid flows by diffusio-osmosis, which become significant at micro- and nano-scales. Here, by means of mesoscopic simulations, we show that a concentration drop across microchannels with periodically inhomogeneous boundary walls can laterally transport fluids over arbitrarily long distances along the microchannel. The driving field is the secondary local chemical gradient parallel to the channel induced by the periodic inhomogeneity of the channel wall. The flow velocity depends on the concentration drop across the channel and the structure and composition of the channel walls, but it is independent of the overall channel length. Our work thus presents new insight into the fluid transport in long microchannels commonly found in nature and is useful for designing novel micro- or nano-fluidic pumps.

  5. concentration

    Directory of Open Access Journals (Sweden)

    Seth F. Oppenheimer

    1999-01-01

    Full Text Available We consider a model for biochemical oxygen demand (BOD in a semi-infinite river where the BOD is prescribed by a time varying function at the left endpoint. That is, we study the problem with a time varying boundary loading. We obtain the well-posedness for the model when the boundary loading is smooth in time. We also obtain various qualitative results such as ordering, positivity, and boundedness. Of greatest interest, we show that a periodic loading function admits a unique asymptotically attracting periodic solution. For non-smooth loading functions, we obtain weak solutions. Finally, for certain special cases, we show how to obtain explicit solutions in the form of infinite series.

  6. Modeling Chemical Reactors I: Quiescent Reactors

    CERN Document Server

    Michoski, C E; Schmitz, P G

    2010-01-01

    We introduce a fully generalized quiescent chemical reactor system in arbitrary space $\\vdim =1,2$ or 3, with $n\\in\\mathbb{N}$ chemical constituents $\\alpha_{i}$, where the character of the numerical solution is strongly determined by the relative scaling between the local reactivity of species $\\alpha_{i}$ and the local functional diffusivity $\\mathscr{D}_{ij}(\\alpha)$ of the reaction mixture. We develop an operator time-splitting predictor multi-corrector RK--LDG scheme, and utilize $hp$-adaptivity relying only on the entropy $\\mathscr{S}_{\\mathfrak{R}}$ of the reactive system $\\mathfrak{R}$. This condition preserves these bounded nonlinear entropy functionals as a necessarily enforced stability condition on the coupled system. We apply this scheme to a number of application problems in chemical kinetics; including a difficult classical problem arising in nonequilibrium thermodynamics known as the Belousov-Zhabotinskii reaction where we utilize a concentration-dependent diffusivity tensor $\\mathscr{D}_{ij}(...

  7. Autonomous Chemical Vapour Detection by Micro UAV

    Directory of Open Access Journals (Sweden)

    Kent Rosser

    2015-12-01

    Full Text Available The ability to remotely detect and map chemical vapour clouds in open air environments is a topic of significant interest to both defence and civilian communities. In this study, we integrate a prototype miniature colorimetric chemical sensor developed for methyl salicylate (MeS, as a model chemical vapour, into a micro unmanned aerial vehicle (UAV, and perform flights through a raised MeS vapour cloud. Our results show that that the system is capable of detecting MeS vapours at low ppm concentration in real-time flight and rapidly sending this information to users by on-board telemetry. Further, the results also indicate that the sensor is capable of distinguishing “clean” air from “dirty”, multiple times per flight, allowing us to look towards autonomous cloud mapping and source localization applications. Further development will focus on a broader range of integrated sensors, increased autonomy of detection and improved engineering of the system.

  8. Chemical kinetics of gas reactions

    CERN Document Server

    Kondrat'Ev, V N

    2013-01-01

    Chemical Kinetics of Gas Reactions explores the advances in gas kinetics and thermal, photochemical, electrical discharge, and radiation chemical reactions. This book is composed of 10 chapters, and begins with the presentation of general kinetic rules for simple and complex chemical reactions. The next chapters deal with the experimental methods for evaluating chemical reaction mechanisms and some theories of elementary chemical processes. These topics are followed by discussions on certain class of chemical reactions, including unimolecular, bimolecular, and termolecular reactions. The rema

  9. Current Chemical Risk Reduction Activities

    Science.gov (United States)

    EPA's existing chemicals programs address pollution prevention, risk assessment, hazard and exposure assessment and/or characterization, and risk management for chemicals substances in commercial use.

  10. Accessing and using chemical databases

    DEFF Research Database (Denmark)

    Nikolov, Nikolai Georgiev; Pavlov, Todor; Niemelä, Jay Russell

    2013-01-01

    , and dissemination. Structure and functionality of chemical databases are considered. The typical kinds of information found in a chemical database are considered-identification, structural, and associated data. Functionality of chemical databases is presented, with examples of search and access types. More details...... are included about the OASIS database and platform and the Danish (Q)SAR Database online. Various types of chemical database resources are discussed, together with a list of examples.......Computer-based representation of chemicals makes it possible to organize data in chemical databases-collections of chemical structures and associated properties. Databases are widely used wherever efficient processing of chemical information is needed, including search, storage, retrieval...

  11. Experiments on chemically enhanced immiscible fluid displacements

    Science.gov (United States)

    Soori, Tejaswi; Ward, Thomas

    2016-11-01

    This talk focuses on experiments conducted by displacing a vegetable oil within a capillary tube (diameter forms a stable micro-emulsion. We estimate the shear viscosity of the emulsion as a function of alkali and aqueous/oil concentrations. Separately we attempt to measure the average bulk diffusion coefficient of the emulsion in both phases which is necessary to estimate the Péclet number (Pé) and subsequent mass transport phenomena. American Chemical Society Petroleum Research Fund.

  12. Impact of oil on groundwater chemical composition

    Science.gov (United States)

    Brakorenko, N. N.

    2015-11-01

    The objective of the paper is to characterize the chemical composition of groundwater samples from the monitoring wells drilled in the petrol station areas within the vicinity of Tomsk. The level of contamination has increased since many macro - and microcomponent concentrations (such as petroleum products, chlorine, sulphates, carbon dioxide and lead, etc.) in groundwater samples of the present study is higher than that in previous period samples.

  13. School concentration and school travel

    NARCIS (Netherlands)

    De Boer, E.

    2010-01-01

    The purpose of the research as described in this Doctor’s thesis is twofold. Firstly it is to define in how far Dutch facilities for primary and secondary education were subjected to spatial concentration during recent decades. Secondly it is intended to assess what this concentration implied for th

  14. Least cost cusp concentrator design

    Energy Technology Data Exchange (ETDEWEB)

    Nanda, S.K.; Mullick, S.C.; Annamalai, M.; Iyer, M.V.; Nirmala, K.A.; Venkatesh, P.; Prasad, C.R.; Subramani, C.

    1982-01-01

    Cusp concentrators require larger reflector areas, but can be designed for larger acceptance angles, allowing large mirror tolerances. Design procedures are outlined to compute the optimum combination of acceptance angle and maximum mirror slope for any required concentration ratio, taking into account the material as well as fabrication costs. The cusps are compared with the parabola.

  15. Biological and Chemical Security

    Energy Technology Data Exchange (ETDEWEB)

    Fitch, P J

    2002-12-19

    The LLNL Chemical & Biological National Security Program (CBNP) provides science, technology and integrated systems for chemical and biological security. Our approach is to develop and field advanced strategies that dramatically improve the nation's capabilities to prevent, prepare for, detect, and respond to terrorist use of chemical or biological weapons. Recent events show the importance of civilian defense against terrorism. The 1995 nerve gas attack in Tokyo's subway served to catalyze and focus the early LLNL program on civilian counter terrorism. In the same year, LLNL began CBNP using Laboratory-Directed R&D investments and a focus on biodetection. The Nunn-Lugar-Domenici Defense Against Weapons of Mass Destruction Act, passed in 1996, initiated a number of U.S. nonproliferation and counter-terrorism programs including the DOE (now NNSA) Chemical and Biological Nonproliferation Program (also known as CBNP). In 2002, the Department of Homeland Security was formed. The NNSA CBNP and many of the LLNL CBNP activities are being transferred as the new Department becomes operational. LLNL has a long history in national security including nonproliferation of weapons of mass destruction. In biology, LLNL had a key role in starting and implementing the Human Genome Project and, more recently, the Microbial Genome Program. LLNL has over 1,000 scientists and engineers with relevant expertise in biology, chemistry, decontamination, instrumentation, microtechnologies, atmospheric modeling, and field experimentation. Over 150 LLNL scientists and engineers work full time on chemical and biological national security projects.

  16. Protein Chemical Shift Prediction

    CERN Document Server

    Larsen, Anders S

    2014-01-01

    The protein chemical shifts holds a large amount of information about the 3-dimensional structure of the protein. A number of chemical shift predictors based on the relationship between structures resolved with X-ray crystallography and the corresponding experimental chemical shifts have been developed. These empirical predictors are very accurate on X-ray structures but tends to be insensitive to small structural changes. To overcome this limitation it has been suggested to make chemical shift predictors based on quantum mechanical(QM) calculations. In this thesis the development of the QM derived chemical shift predictor Procs14 is presented. Procs14 is based on 2.35 million density functional theory(DFT) calculations on tripeptides and contains corrections for hydrogen bonding, ring current and the effect of the previous and following residue. Procs14 is capable at performing predictions for the 13CA, 13CB, 13CO, 15NH, 1HN and 1HA backbone atoms. In order to benchmark Procs14, a number of QM NMR calculatio...

  17. Chemically Powered Nanomotors

    Science.gov (United States)

    Kapral, Raymond

    2007-03-01

    Molecular motors play important roles in transport in biological systems. These molecular machines are powered by chemical energy and operate in the regime of low Reynolds number hydrodynamics. Recently a class of simple inorganic molecular motors has been constructed and studied experimentally [1,2]. These motors are bimetallic rods, one end of which is chemically active. The talk will describe simple mesoscopic models for the motion of such nanomotors. The motor consists of two linked spheres, one of which catalyzes the conversion between two chemical species. The chemical species interact differently with the the two spheres in the dimer. The nano-dimer motor is solvated by a molecules treated at a mesoscopic level whose evolution is governed by multi-particle collision dynamics. The dynamics conserves mass, momentum and energy so that coupling between the nanomotor and the hydrodynamic modes of the solvent is treated correctly. The simulations allow one to explore the mechanisms of the chemically powered motion and the effects of fluctuations on the motor dynamics. [1] W. F. Paxton, et al., ``Catalytic Nanomotors: Autonomous Movement of Striped Nanorods,'' J. Am. Chem. Soc. (JACS), 126 (41), 13424 (2004). [2] S. Fournier-Bidoz, et al. ``Synthetic Self-Propelled Nanorotors,'' Chem. Commun., (4), 441 (2005).

  18. Flame Propagation Through Concentration Gradient

    Institute of Scientific and Technical Information of China (English)

    JunyaIINO; MitsuakiTANABE; 等

    2000-01-01

    The experiment was carried out in homogeneous propane-air mixture and in several concentration gradient of mixture.Igniter is put on the upper side of the combustion chamber,In concentration gradient experiment.ixture was ignited from lean side.An experimental study was conducted in a combustion chamber.The combustion chamber has glass windows for optical measurements at any side.For the measurement of distribution of fuel concentration,infraed absorption method using 3.39μm He-Ne laser was used,and for the observation of proagating flams,Schlieren method was employed.As a measurment result of flame propagation velocity and flammable limit,for a mixture of an identical local equivalence ratio.flame propagation velocity in concentration gradient is faster than that in homogeneous mixture,and rich flammable limit in concentration gradient shows a tendency to be higher than that in homogeneous mixture.

  19. Arrays of coupled chemical oscillators

    CERN Document Server

    Forrester, Derek Michael

    2016-01-01

    Oscillating chemical reactions result from complex periodic changes in the concentration of the reactants. In spatially ordered ensembles of candle flame oscillators the fluctuations in the ratio of oxygen atoms with respect to that of carbon, hydrogen and nitrogen produces an oscillation in the visible part of the flame related to the energy released per unit mass of oxygen. Thus, the products of the reaction vary in concentration as a function of time, giving rise to an oscillation in the amount of soot and radiative emission. Synchronisation of interacting dynamical sub-systems occurs as arrays of flames that act as master and slave oscillators, with groups of candles numbering greater than two, creating a synchronised motion in three-dimensions. In a ring of candles the visible parts of each flame move together, up and down and back and forth, in a manner that appears like a "worship". Here this effect is shown for rings of flames which collectively empower a central flame to pulse to greater heights. In ...

  20. Chemical Stabilization of Hanford Tank Residual Waste

    Energy Technology Data Exchange (ETDEWEB)

    Cantrell, Kirk J.; Um, Wooyong; Williams, Benjamin D.; Bowden, Mark E.; Gartman, Brandy N.; Lukens, Wayne W.; Buck, Edgar C.; Mausolf, Edward J.

    2014-03-01

    Three different chemical treatment methods were tested for their ability to stabilize residual waste from Hanford tank C-202 for reducing contaminant release (Tc, Cr, and U in particular). The three treatment methods tested were lime addition [Ca(OH)2], an in-situ Ceramicrete waste form based on chemically bonded phosphate ceramics, and a ferrous iron/goethite treatment. These approaches rely on formation of insoluble forms of the contaminants of concern (lime addition and ceramicrete) and chemical reduction followed by co-precipitation (ferrous iron/goethite incorporation treatment). The results have demonstrated that release of the three most significant mobile contaminants of concern from tank residual wastes can be dramatically reduced after treatment compared to contact with simulated grout porewater without treatment. For uranium, all three treatments methods reduced the leachable uranium concentrations by well over three orders of magnitude. In the case of uranium and technetium, released concentrations were well below their respective MCLs for the wastes tested. For tank C-202 residual waste, chromium release concentrations were above the MCL but were considerably reduced relative to untreated tank waste. This innovative approach has the potential to revolutionize Hanford’s tank retrieval process, by allowing larger volumes of residual waste to be left in tanks while providing an acceptably low level of risk with respect to contaminant release that is protective of the environment and human health. Such an approach could enable DOE to realize significant cost savings through streamlined retrieval and closure operations.

  1. Chemical stabilization of Hanford tank residual waste

    Science.gov (United States)

    Cantrell, Kirk J.; Um, Wooyong; Williams, Benjamin D.; Bowden, Mark E.; Gartman, Brandy; Lukens, Wayne W.; Buck, Edgar C.; Mausolf, Edward J.

    2014-03-01

    Three different chemical treatment methods were tested for their ability to stabilize residual waste from Hanford tank C-202 for reducing contaminant release (Tc, Cr, and U in particular). The three treatment methods tested were lime addition [Ca(OH)2], an in situ Ceramicrete waste form based on chemically bonded phosphate ceramics, and a ferrous iron/goethite treatment. These approaches rely on formation of insoluble forms of the contaminants of concern (lime addition and Ceramicrete) and chemical reduction followed by co-precipitation (ferrous iron/goethite incorporation treatment). The results have demonstrated that release of uranium from tank residual wastes can be dramatically reduced after treatment compared to contact with simulated grout porewater without treatment. All three treatments methods reduced the leachable uranium concentrations by well over three orders of magnitude. In the case of uranium and technetium, released concentrations were well below their respective Maximum Contaminant Levels (MCLs) for the wastes tested. For tank C-202 residual waste, chromium release concentrations were above the MCL but were considerably reduced relative to untreated tank waste.

  2. Chemical stabilization of Hanford tank residual waste

    Energy Technology Data Exchange (ETDEWEB)

    Cantrell, Kirk J., E-mail: kirk.cantrell@pnnl.gov [Pacific Northwest National Laboratory, Richland, WA 99352 (United States); Um, Wooyong; Williams, Benjamin D.; Bowden, Mark E.; Gartman, Brandy [Pacific Northwest National Laboratory, Richland, WA 99352 (United States); Lukens, Wayne W. [Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Buck, Edgar C.; Mausolf, Edward J. [Pacific Northwest National Laboratory, Richland, WA 99352 (United States)

    2014-03-15

    Three different chemical treatment methods were tested for their ability to stabilize residual waste from Hanford tank C-202 for reducing contaminant release (Tc, Cr, and U in particular). The three treatment methods tested were lime addition [Ca(OH){sub 2}], an in situ Ceramicrete waste form based on chemically bonded phosphate ceramics, and a ferrous iron/goethite treatment. These approaches rely on formation of insoluble forms of the contaminants of concern (lime addition and Ceramicrete) and chemical reduction followed by co-precipitation (ferrous iron/goethite incorporation treatment). The results have demonstrated that release of uranium from tank residual wastes can be dramatically reduced after treatment compared to contact with simulated grout porewater without treatment. All three treatments methods reduced the leachable uranium concentrations by well over three orders of magnitude. In the case of uranium and technetium, released concentrations were well below their respective Maximum Contaminant Levels (MCLs) for the wastes tested. For tank C-202 residual waste, chromium release concentrations were above the MCL but were considerably reduced relative to untreated tank waste. This innovative approach has the potential to revolutionize Hanford’s tank retrieval process, by allowing larger volumes of residual waste to be left in tanks while providing an acceptably low level of risk with respect to contaminant release that is protective of the environment and human health. Such an approach could enable DOE to realize significant cost savings through streamlined retrieval and closure operations.

  3. Chemical composition of interstellar dust

    Science.gov (United States)

    Das, Ankan; Chakrabarti, Sandip Kumar; Majumdar, Liton; Sahu, Dipen

    Study of chemical evolution of interstellar medium is well recognized to be a challenging task. Interstellar medium (ISM) is a rich reservoir of complex molecules. So far, around 180 gas phase molecules and around 20 molecular species on the interstellar dust have been detected in various regions of ISM, especially in regions of star formation. In last decade, it was well established that gas phase reactions alone cannot explain molecular abundances in ISM. Chemical reactions which occur on interstellar dust grains are essential to explain formation of several molecules especially hydrogenated species including simplest and most abundant molecule H2. Interstellar grains provide surface for accreted species to meet and react. Therefore, an understanding of formation of molecules on grain surfaces is of prime importance. We concentrate mainly on water, methanol, carbon dioxide, which constitute nearly 90% of the grain mantle. These molecules are detected on grain surface due to their strong absorption bands arising out of multiple vibrational modes. Water is the most abundant species (with a surface coverage >60% ) on a grain in dense interstellar medium. CO2 is second most abundant molecule in interstellar medium with an abundance of around 20% with respect to H2O. However, this can vary from cloud to cloud. In clouds like W 33A it could be even less than 5% of water abundance. The next most abundant molecule is CO, which is well studied ice with an abundance varying between 2%\\ to 15% of water. Methanol (CH3OH) is also very abundant having abundance 2% to 30% of water. Measurement of water deuterium fractionation is a relevant tool for understanding mechanisms of water formation and evolution from prestellar phase to formation of planets and comets. We are also considering deuterated species in our simulation. We use Monte Carlo method (considering multilayer regime) to mimic the exact scenario. We study chemical evolution of interstellar grain mantle by varying

  4. Nanotechnology for chemical engineers

    CERN Document Server

    Salaheldeen Elnashaie, Said; Hashemipour Rafsanjani, Hassan

    2015-01-01

    The book describes the basic principles of transforming nano-technology into nano-engineering with a particular focus on chemical engineering fundamentals. This book provides vital information about differences between descriptive technology and quantitative engineering for students as well as working professionals in various fields of nanotechnology. Besides chemical engineering principles, the fundamentals of nanotechnology are also covered along with detailed explanation of several specific nanoscale processes from chemical engineering point of view. This information is presented in form of practical examples and case studies that help the engineers and researchers to integrate the processes which can meet the commercial production. It is worth mentioning here that, the main challenge in nanostructure and nanodevices production is nowadays related to the economic point of view. The uniqueness of this book is a balance between important insights into the synthetic methods of nano-structures and nanomaterial...

  5. Rapid chemical separations

    CERN Document Server

    Trautmann, N

    1976-01-01

    A survey is given on the progress of fast chemical separation procedures during the last few years. Fast, discontinuous separation techniques are illustrated by a procedure for niobium. The use of such techniques for the chemical characterization of the heaviest known elements is described. Other rapid separation methods from aqueous solutions are summarized. The application of the high speed liquid chromatography to the separation of chemically similar elements is outlined. The use of the gas jet recoil transport method for nuclear reaction products and its combination with a continuous solvent extraction technique and with a thermochromatographic separation is presented. Different separation methods in the gas phase are briefly discussed and the attachment of a thermochromatographic technique to an on-line mass separator is shown. (45 refs).

  6. Translated chemical reaction networks.

    Science.gov (United States)

    Johnston, Matthew D

    2014-05-01

    Many biochemical and industrial applications involve complicated networks of simultaneously occurring chemical reactions. Under the assumption of mass action kinetics, the dynamics of these chemical reaction networks are governed by systems of polynomial ordinary differential equations. The steady states of these mass action systems have been analyzed via a variety of techniques, including stoichiometric network analysis, deficiency theory, and algebraic techniques (e.g., Gröbner bases). In this paper, we present a novel method for characterizing the steady states of mass action systems. Our method explicitly links a network's capacity to permit a particular class of steady states, called toric steady states, to topological properties of a generalized network called a translated chemical reaction network. These networks share their reaction vectors with their source network but are permitted to have different complex stoichiometries and different network topologies. We apply the results to examples drawn from the biochemical literature.

  7. Precision Chemical Abundance Measurements

    DEFF Research Database (Denmark)

    Yong, David; Grundahl, Frank; Meléndez, Jorge;

    2012-01-01

    This talk covers preliminary work in which we apply a strictly differential line-by-line chemical abundance analysis to high quality UVES spectra of the globular cluster NGC 6752. We achieve extremely high precision in the measurement of relative abundance ratios. Our results indicate that the ob......This talk covers preliminary work in which we apply a strictly differential line-by-line chemical abundance analysis to high quality UVES spectra of the globular cluster NGC 6752. We achieve extremely high precision in the measurement of relative abundance ratios. Our results indicate...... that the observed abundance dispersion exceeds the measurement uncertainties and that many pairs of elements show significant correlations when plotting [X1/H] vs. [X2/H]. Our tentative conclusions are that either NGC 6752 is not chemically homogeneous at the ~=0.03 dex level or the abundance variations...

  8. Chemical Inhibition of Autophagy

    DEFF Research Database (Denmark)

    Baek, Eric; Lin Kim, Che; Gyeom Kim, Mi;

    2016-01-01

    Chinese hamster ovary (CHO) cells activate and undergo apoptosis and autophagy for various environmental stresses. Unlike apoptosis, studies on increasing the production of therapeutic proteins in CHO cells by targeting the autophagy pathway are limited. In order to identify the effects of chemical...... autophagy inhibitors on the specific productivity (qp), nine chemical inhibitors that had been reported to target three different phases of autophagy (metformin, dorsomorphin, resveratrol, and SP600125 against initiation and nucleation; 3-MA, wortmannin, and LY294002 against elongation, and chloroquine...... and bafilomycin A1 against autophagosome fusion) were used to treat three recombinant CHO (rCHO) cell lines: the Fc-fusion protein-producing DG44 (DG44-Fc) and DUKX-B11 (DUKX-Fc) and antibody-producing DG44 (DG44-Ab) cell lines. Among the nine chemical inhibitors tested, 3-MA, dorsomorphin, and SP600125...

  9. Applied chemical engineering thermodynamics

    CERN Document Server

    Tassios, Dimitrios P

    1993-01-01

    Applied Chemical Engineering Thermodynamics provides the undergraduate and graduate student of chemical engineering with the basic knowledge, the methodology and the references he needs to apply it in industrial practice. Thus, in addition to the classical topics of the laws of thermodynamics,pure component and mixture thermodynamic properties as well as phase and chemical equilibria the reader will find: - history of thermodynamics - energy conservation - internmolecular forces and molecular thermodynamics - cubic equations of state - statistical mechanics. A great number of calculated problems with solutions and an appendix with numerous tables of numbers of practical importance are extremely helpful for applied calculations. The computer programs on the included disk help the student to become familiar with the typical methods used in industry for volumetric and vapor-liquid equilibria calculations.

  10. Chemical inhomogeneities and pulsation

    CERN Document Server

    Turcotte, S

    2001-01-01

    Major improvements in models of chemically peculiar stars have been achieved in the past few years. With these new models it has been possible to test quantitatively some of the processes involved in the formation of abundance anomalies and their effect on stellar structure. The models of metallic A (Am) stars have shown that a much deeper mixing has to be present to account for observed abundance anomalies. This has implications on their variability, which these models also reproduce qualitatively. These models also have implications for other chemically inhomogeneous stars such as HgMn B stars which are not known to be variable and lambda Bootis stars which can be. The study of the variability of chemically inhomogeneous stars can provide unique information on the dynamic processes occurring in many types of stars in addition to modeling of the evolution of their surface composition.

  11. Chemical Kinetics Database

    Science.gov (United States)

    SRD 17 NIST Chemical Kinetics Database (Web, free access)   The NIST Chemical Kinetics Database includes essentially all reported kinetics results for thermal gas-phase chemical reactions. The database is designed to be searched for kinetics data based on the specific reactants involved, for reactions resulting in specified products, for all the reactions of a particular species, or for various combinations of these. In addition, the bibliography can be searched by author name or combination of names. The database contains in excess of 38,000 separate reaction records for over 11,700 distinct reactant pairs. These data have been abstracted from over 12,000 papers with literature coverage through early 2000.

  12. Chemicals in material cycles

    DEFF Research Database (Denmark)

    Pivnenko, Kostyantyn; Eriksson, Eva; Astrup, Thomas Fruergaard

    2015-01-01

    Material recycling has been found beneficial in terms of resource and energy performance and is greatly promoted throughout the world. A variety of chemicals is used in materials as additives and data on their presence is sparse. The present work dealt with paper as recyclable material and diisob......Material recycling has been found beneficial in terms of resource and energy performance and is greatly promoted throughout the world. A variety of chemicals is used in materials as additives and data on their presence is sparse. The present work dealt with paper as recyclable material...... and diisobutyl phthalate (DiBP) as chemical in focus. The results showed variations, between 0.83 and 32 μg/g, in the presence of DiBP in Danish waste paper and board and potential accumulation due to recycling....

  13. Endocrine disrupting chemicals

    DEFF Research Database (Denmark)

    Mandrup, Karen

    BACKGROUND: Endocrine disrupting chemicals (EDCs) may contribute to reproductive changes in boys in the Western world, however, less is known about influence of EDCs in women. The incidence of precocious breast development is increasing in USA and Europe and mammary gland development has been...... suggested as particularly sensitive to endocrine disruption. Mammary gland examination in toxicological studies may be useful for improving knowledge on possible influences of EDCs on human mammary glands and also be useful for detection of endocrine disrupting effects of chemicals as part of safety testing...... and genistein, a mixture of phytoestrogens, and a mixture of environmentally relevant estrogenic EDCs of various origins. Moreover, mixtures of antiandrogenic chemicals were investigated. These include a mixture of pesticides and a mixture of environmentally relevant anti-androgenic EDCs of various origins...

  14. Peanut cake concentrations in massai grass silage

    Directory of Open Access Journals (Sweden)

    Luciano S. Lima

    2013-03-01

    Full Text Available Objective. This experiment was conducted to evaluate the best concentration of peanut cake in the ensiling of massai grass of the chemical-bromatological composition, fermentative characteristics, forage value rate, ingestion estimates, and digestibility of dry matter in the silage. Materials and methods. The experiment was carried out at the Experimental Farm of São Gonçalo dos Campos at the Federal University of Bahia, Brazil. The treatments consisted of massai grass that was cut at 40 days and dehydrated, in addition to 0%, 8%, 16%, and 24% peanut cake in the fresh matter and treatment without cake. The material was compressed in experimental silos (7 liter that were opened after 76 days. Results. The addition of 8-24% peanut cake improved the silage’s chemical-bromatological parameters, increased the dry matter and non-fiber carbohydrates and reduced the fibrous components. There was a linear increase in the estimated values of digestibility and the ingestion of dry matter depending on the levels of peanut cake in the silage. There was an improvement in the fermentative characteristics, with a quadratic effect positive for levels of ammoniacal nitrogen. The forage value rate increased linearly with the inclusion of peanut cake. Conclusions. The inclusion of up to 24% peanut cake during ensiling of massai grass increases the nutritive value of silage and improves fermentation characteristics.

  15. Chemical profiling of chemical warfare agents for forensic purposes

    NARCIS (Netherlands)

    Noort, D.; Reuver, L.P.J. de; Fidder, A.; Tromp, M.; Verschraagen, M.

    2010-01-01

    A program has been initiated towards the chemical profiling of chemical warfare agents, in order to support forensic investigations towards synthesis routes, production sites and suspect chemical suppliers. Within the first stage of the project various chemical warfare agents (VX, sulfur mustard, sa

  16. Idaho Chemical Processing Plant safety document ICPP hazardous chemical evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Harwood, B.J.

    1993-01-01

    This report presents the results of a hazardous chemical evaluation performed for the Idaho Chemical Processing Plant (ICPP). ICPP tracks chemicals on a computerized database, Haz Track, that contains roughly 2000 individual chemicals. The database contains information about each chemical, such as its form (solid, liquid, or gas); quantity, either in weight or volume; and its location. The Haz Track database was used as the primary starting point for the chemical evaluation presented in this report. The chemical data and results presented here are not intended to provide limits, but to provide a starting point for nonradiological hazards analysis.

  17. Principles of chemical kinetics

    CERN Document Server

    House, James E

    2007-01-01

    James House's revised Principles of Chemical Kinetics provides a clear and logical description of chemical kinetics in a manner unlike any other book of its kind. Clearly written with detailed derivations, the text allows students to move rapidly from theoretical concepts of rates of reaction to concrete applications. Unlike other texts, House presents a balanced treatment of kinetic reactions in gas, solution, and solid states. The entire text has been revised and includes many new sections and an additional chapter on applications of kinetics. The topics covered include quantitative rela

  18. Chemical allergy in humans

    DEFF Research Database (Denmark)

    Kimber, Ian; Basketter, David A; Thyssen, Jacob P

    2014-01-01

    functional sub-populations of CD4(+) and CD8(+) T-lymphocytes. Evidence for a similar association of chemical allergy in humans with discrete T-lymphocyte populations is, however, limited. It is of some interest, therefore, that two recent articles from different teams of investigators have shed new light...... on the role of polarized T-lymphocyte responses in the development of allergic contact dermatitis and occupational asthma in humans. The implications for understanding of chemical allergy in humans are explored in this Commentary....

  19. Chemical space and biology.

    Science.gov (United States)

    Dobson, Christopher M

    2004-12-16

    Chemical space--which encompasses all possible small organic molecules, including those present in biological systems--is vast. So vast, in fact, that so far only a tiny fraction of it has been explored. Nevertheless, these explorations have greatly enhanced our understanding of biology, and have led to the development of many of today's drugs. The discovery of new bioactive molecules, facilitated by a deeper understanding of the nature of the regions of chemical space that are relevant to biology, will advance our knowledge of biological processes and lead to new strategies to treat disease.

  20. CHEMICAL TOXICITY OF URANIUM

    Directory of Open Access Journals (Sweden)

    Sermin Cam

    2007-06-01

    Full Text Available Uranium, occurs naturally in the earth’s crust, is an alpha emitter radioactive element from the actinide group. For this reason, U-235 and U-238, are uranium isotopes with long half lives, have got radiological toxicity. But, for natural-isotopic-composition uranium (NatU, there is greater risk from chemical toxicity than radiological toxicity. When uranium is get into the body with anyway, also its chemical toxicity must be thought. [TAF Prev Med Bull 2007; 6(3.000: 215-220

  1. Solar Concentrator Advanced Development Program

    Science.gov (United States)

    Knasel, Don; Ehresman, Derik

    1989-01-01

    The Solar Concentrator Advanced Development Project has successfully designed, fabricated, and tested a full scale prototypical solar dynamic concentrator for space station applications. A Truss Hexagonal Panel reflector was selected as a viable solar concentrator concept to be used for space station applications. This concentrator utilizes a modular design approach and is flexible in attainable flux profiles and assembly techniques. The detailed design of the concentrator, which included structural, thermal and optical analysis, identified the feasibility of the design and specific technologies that were required to fabricate it. The needed surface accuracy of the reflectors surface was found to be very tight, within 5 mrad RMS slope error, and results in very close tolerances for fabrication. To meet the design requirements, a modular structure composed of hexagonal panels was used. The panels, made up of graphite epoxy box beams provided the strength, stiffness and dimensional stability needed. All initial project requirements were met or exceeded by hardware demonstration. Initial testing of structural repeatability of a seven panel portion of the concentrator was followed by assembly and testing of the full nineteen panel structure. The testing, which consisted of theodolite and optical measurements over an assembly-disassembly-reassembly cycle, demonstrated that the concentrator maintained the as-built contour and optical characteristics. The facet development effort within the project, which included developing the vapor deposited reflective facet, produced a viable design with demonstrated optical characteristics that are within the project goals.

  2. Improved exposure estimation in soil screening and clean-up criteria for volatile organic chemicals.

    Science.gov (United States)

    DeVaull, George E

    2017-02-18

    Soil clean-up criteria define acceptable concentrations of organic chemical constituents for exposed humans. These criteria sum the estimated soil exposure over multiple pathways. Assumptions for ingestion, dermal contact, and dust exposure generally presume a chemical persists in surface soils at a constant concentration level for the entire exposure duration. For volatile chemicals this is an unrealistic assumption. A calculation method is presented for surficial soil criteria which include volatile depletion of chemical for these uptake pathways. The depletion estimates compare favorably with measured concentration profiles and with field measurements of soil concentration. Corresponding volatilization estimates compare favorably with measured data for a wide range of volatile and semi-volatile chemicals, including instances with and without the presence of a mixed-chemical residual phase. Selected examples show application of the revised factors in estimating screening levels for benzene in surficial soils. This article is protected by copyright. All rights reserved.

  3. Remote Chemical Sensing Using Quantum Cascade Lasers

    Energy Technology Data Exchange (ETDEWEB)

    Harper, Warren W.; Schultz, John F.

    2003-01-30

    Spectroscopic chemical sensing research at Pacific Northwest National Laboratory (PNNL) is focused on developing advanced sensors for detecting the production of nuclear, chemical, or biological weapons; use of chemical weapons; or the presence of explosives, firearms, narcotics, or other contraband of significance to homeland security in airports, cargo terminals, public buildings, or other sensitive locations. For most of these missions, the signature chemicals are expected to occur in very low concentrations, and in mixture with ambient air or airborne waste streams that contain large numbers of other species that may interfere with spectroscopic detection, or be mistaken for signatures of illicit activity. PNNL’s emphasis is therefore on developing remote and sampling sensors with extreme sensitivity, and resistance to interferents, or selectivity. PNNL’s research activities include: 1. Identification of signature chemicals and quantification of their spectral characteristics, 2. Identification and development of laser and other technologies that enable breakthroughs in sensitivity and selectivity, 3. Development of promising sensing techniques through experimentation and modeling the physical phenomenology and practical engineering limitations affecting their performance, and 4. Development and testing of data collection methods and analysis algorithms. Close coordination of all aspects of the research is important to ensure that all parts are focused on productive avenues of investigation. Close coordination of experimental development and numerical modeling is particularly important because the theoretical component provides understanding and predictive capability, while the experiments validate calculations and ensure that all phenomena and engineering limitations are considered.

  4. Chemical reactions confined within carbon nanotubes.

    Science.gov (United States)

    Miners, Scott A; Rance, Graham A; Khlobystov, Andrei N

    2016-08-22

    In this critical review, we survey the wide range of chemical reactions that have been confined within carbon nanotubes, particularly emphasising how the pairwise interactions between the catalysts, reactants, transition states and products of a particular molecular transformation with the host nanotube can be used to control the yields and distributions of products of chemical reactions. We demonstrate that nanoscale confinement within carbon nanotubes enables the control of catalyst activity, morphology and stability, influences the local concentration of reactants and products thus affecting equilibria, rates and selectivity, pre-arranges the reactants for desired reactions and alters the relative stability of isomeric products. We critically evaluate the relative advantages and disadvantages of the confinement of chemical reactions inside carbon nanotubes from a chemical perspective and describe how further developments in the controlled synthesis of carbon nanotubes and the incorporation of multifunctionality are essential for the development of this ever-expanding field, ultimately leading to the effective control of the pathways of chemical reactions through the rational design of multi-functional carbon nanoreactors.

  5. Chemical composition of inks of diverse marine molluscs suggests convergent chemical defenses.

    Science.gov (United States)

    Derby, Charles D; Kicklighter, Cynthia E; Johnson, P M; Zhang, Xu

    2007-05-01

    Some marine molluscs, notably sea hares, cuttlefish, squid, and octopus, release ink when attacked by predators. The sea hare Aplysia californica releases secretions from the ink gland and opaline gland that protect individuals from injury or death from predatory spiny lobsters through a combination of mechanisms that include chemical deterrence, sensory disruption, and phagomimicry. The latter two mechanisms are facilitated by millimolar concentrations of free amino acids (FAA) in sea hare ink and opaline, which stimulate the chemosensory systems of predators, ultimately leading to escape by sea hares. We hypothesize that other inking molluscs use sensory disruption and/or phagomimicry as a chemical defense. To investigate this, we examined concentrations of 21 FAA and ammonium in the defensive secretions of nine species of inking molluscs: three sea hares (Aplysia californica, Aplysia dactylomela, Aplysia juliana) and six cephalopods (cuttlefish: Sepia officinalis; squid: Loligo pealei, Lolliguncula brevis, Dosidicus gigas; octopus: Octopus vulgaris, Octopus bimaculoides). We found millimolar levels of total FAA and ammonium in these secretions, and the FAA in highest concentration were taurine, aspartic acid, glutamic acid, alanine, and lysine. Crustaceans and fish, which are major predators of these molluscs, have specific receptor systems for these FAA. Our chemical analysis supports the hypothesis that inking molluscs have the potential to use sensory disruption and/or phagomimicry as a chemical defense.

  6. Development of techniques for tagging precursor and essential chemicals

    Energy Technology Data Exchange (ETDEWEB)

    Swansiger, W.A.; Shepodd, T.J. [Sandia National Labs., Livermore, CA (United States); Phillips, M.L.F. [Sandia National Labs., Albuquerque, NM (United States)

    1994-01-01

    The ability to identify the manufacturers and distributors of chemicals seized in raids of illicit drug labs would be of great value in controlling the diversion of these chemicals. We developed a tagging scheme based on the addition of sub-ppM concentrations of various combinations of rare-earth elements to the target chemicals and evaluated a number of techniques for detecting the tags. We developed soluble tags for tagging liquids and selected Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) as the preferred detection technique. We developed insoluble tags for tagging solids and developed methods to analyze them and mix them into solid precursors. We have successfully demonstrated the tagging of several solvents and two of the precursor chemicals used in one of the most popular clandestine methamphetamine syntheses (ephedrine reacting with hydriodic acid/red phosphorus). The tagging scheme is capable of yielding tens of thousands of signatures (using holmium as an internal standard and up to 9 rare-earths at up to 3 concentrations yields 3{sup 9} {minus} 1 = 19,682 signatures) and is applicable to most of the chemicals on the precursor and essential chemicals list. In the concentrations employed, the tags are safe enough to be added to pharmaceuticals and cheap enough to tag tanker loads of chemicals.

  7. Environmental Chemicals in Breast Milk

    Science.gov (United States)

    Most of the information available on environmental chemicals in breast milk is focused on persistent, lipophilic chemicals; the database on levels of these chemicals has expanded substantially since the 1950s. Currently, various types of chemicals are measured in breast milk and ...

  8. ELECTROLYTIC CORROSION OF GOLD AND THE FORMATION OF Au//2(SO//4)//3 IN CONCENTRATED SULFURIC ACID.

    Science.gov (United States)

    Senftle, Frank E.; Wright, Donald B.

    1985-01-01

    The authors have examined the direct anodic oxidation of gold in concentrated H//2SO//4 to more fully understand the chemical reactions. Au//2(SO//4)//3 is unstable and cannot be isolated for chemical analysis, but our experiments are consistent with the formation of Au//2(SO//4)//3 in concentrated H//2SO//4, in which it is stable. Equations describing chemical reactions which are compatible with the experimental data are presented.

  9. Capture, transformation and conversion of the solar energy by the technologies of concentration; Captation, transformation et conversion de l'energie solaire par les technologies a concentration

    Energy Technology Data Exchange (ETDEWEB)

    Ferriere, A.; Flamant, G

    2003-07-01

    The specificities of the solar technologies at concentration are: high energy efficiency with increasing possibilities and the possibility of storage the solar energy by heat for a local and short dated utilization or by chemical storage (hydrogen for instance) for a delayed utilization or far from the capture area. This document takes stock on the concentration solar techniques, the electric power production by concentrated solar energy and the performance of concentrated solar plants, the industrial american experience of the SEGS plants, the hydrogen production by concentrated solar energy and discusses the scientific and technological locks. (A.L.B.)

  10. Chemical hygiene plan

    Energy Technology Data Exchange (ETDEWEB)

    1994-09-01

    This plan was written to administer and monitor safety measures and chemical hygiene principles in the TAC Uranium Mill Tailing Remedial Action Project sample preparation facility in Albuquerque, New Mexico. It applies to toxic and/or hazardous materials to radioactive materials.

  11. Chemical Product Design

    DEFF Research Database (Denmark)

    Gani, Rafiqul

    2004-01-01

    This paper highlights for a class of chemical products, the design process, their design with respect to the important issues, the need for appropriate tools and finally, lists some of the challenges and opportunities for the process systems engineering (PSE)/computer-aided process engineering...

  12. Chemical and Petrochemical Sector

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2009-07-01

    This publication is a background document on the global chemical and petrochemical sector for the IEA publication Energy Technology Transitions in Industry (IEA, 2009). It provides further, more detailed information on the methodology and data issues for energy efficiency indicators for the sector. The indicators discussed offer insight regarding the energy efficiency improvement potential in the short- to medium-term (by proven technologies).

  13. The renewable chemicals industry

    DEFF Research Database (Denmark)

    Christensen, Claus H.; Rass-Hansen, J.; Marsden, Charlotte Clare;

    2008-01-01

    The possibilities for establishing a renewable chemicals industry featuring renewable resources as the dominant feedstock rather than fossil resources are discussed in this Concept. Such use of biomass can potentially be interesting from both an economical and ecological perspective. Simple and e...

  14. Chemically Reacting Turbulent Flow.

    Science.gov (United States)

    1987-04-14

    two stages of gen I tubes equipped with P-47 phosphor screens The detector chosen for the camera was a Reticon RL128S* line detectoI- .,hich consists...the Stud’, of Turbulent Mixing," William M. Pitts, Nuclear Engineering Seminar of the Department of Chemical and Nuclear Engineering, University of

  15. Chemical Absorption Materials

    DEFF Research Database (Denmark)

    Thomsen, Kaj

    2011-01-01

    Chemical absorption materials that potentially can be used for post combustion carbon dioxide capture are discussed. They fall into five groups, alkanolamines, alkali carbonates, ammonia, amino acid salts, and ionic liquids. The chemistry of the materials is discussed and advantages and drawbacks...

  16. Chemical Safety – Introduction

    CERN Multimedia

    DG Unit

    2009-01-01

    A course of "Chemical Safety – Introduction" will be held in English on 29 May 2009, 9:30-12:00. There are some places left. If you are interested in participating, please register on the Training Catalogue. You will then receive an invitation by email.

  17. Multiple Chemical Sensitivity

    DEFF Research Database (Denmark)

    Junge, Anne Gram

    Et voksende antal mennesker i Danmark oplever at være overfølsomme over for dufte og kemikalier. Imidlertid er den tilskrevne diagnose Multiple Chemical Sensitivity (MCS) ikke medicinsk anerkendt i Danmark pga. mangel på organiske og patofysiologisk basis for symptomerne. Dette speciale bygger på...

  18. Hydroxyl Radical Chemical Laser

    Science.gov (United States)

    1977-11-01

    Stone (I) 1 Atlantic Research Corporation, Alexandria, VA (Robert Naismith ) I Battelle Columbus laboratories, Columbus, OH (Fred Tietzel) 1...Corporation, Santa Monica, CA (Dr. Claude R. Culp) 1 Thiokol Chemical Corporation, Wasatch Division, Brigham City, UT ( James E. Hansen) 4 United

  19. Chemical Aspects of Dentistry.

    Science.gov (United States)

    Helfman, Murry

    1982-01-01

    Dental caries (tooth decay) and periodontal (gum) disease are treated/prevented by procedures utilizing chemical expertise. Procedures and suggestions on how they might be incorporated into the high school chemistry curriculum are described. Specific topics discussed include dental caries, fluoride, diet, tooth decay prevention, silver amalgan,…

  20. Chemical defences against herbivores

    DEFF Research Database (Denmark)

    Pavia, Henrik; Baumgartner, Finn; Cervin, Gunnar;

    2012-01-01

    of these theories, concluding with new chemical approaches to tackle the questions and suggestions for future research directions. It explains that aquatic primary producers are a taxonomically and functionally diverse group of organisms that includes macroalgae, microalgae, and vascular plants. It also states...

  1. Plant Diseases & Chemicals

    OpenAIRE

    Thompson, Sherm

    2008-01-01

    This course discusses the use of chemicals for plant disease control. Specifically, pesticides that can be used both in commercial or home/yard sitautions. This course also teaches how to determine plant diseases that may have caused a plant to die.

  2. Chemicals of Common bitercress

    Directory of Open Access Journals (Sweden)

    M. Marenich

    2012-12-01

    Full Text Available Article is devoted to the study of the chemical composition of Common bitter cress (Barbarea vulgaris R. Br.. Shows indicators of good quality, optimal parameters extraction, trace element composition, amino acid composition, content of biologically active substances and volatile of raw material.

  3. Power plant chemical technology

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-12-01

    17 contributions covering topies of fossil fuel combustion, flue gas cleaning, power plant materials, corrosion, water/steam cycle chemistry, monitoring and control were presented at the annual meeting devoted to Power Plant Chemical Technology 1996 at Kolding (Denmark) 4-6 September 1996. (EG)

  4. Bulk chemicals from biomass

    NARCIS (Netherlands)

    Haveren, van J.; Scott, E.L.; Sanders, J.P.M.

    2008-01-01

    Given the current robust forces driving sustainable production, and available biomass conversion technologies, biomass-based routes are expected to make a significant impact on the production of bulk chemicals within 10 years, and a huge impact within 20-30 years. In the Port of Rotterdam there is a

  5. High estrogen concentrations in receiving river discharge from a concentrated livestock feedlot.

    Science.gov (United States)

    Chen, Te-San; Chen, Ting-Chien; Yeh, Kuei-Jyum C; Chao, How-Ran; Liaw, Ean-Tun; Hsieh, Chi-Ying; Chen, Kuan-Chung; Hsieh, Lien-Te; Yeh, Yi-Lung

    2010-07-15

    Environmental estrogenic chemicals interrupt endocrine systems and generate reproductive abnormalities in wildlife, especially natural and synthetic estrogenic steroid hormones such as 17beta-estradiol (E2), estrone (E1), estriol (E3), 17alpha-ethynylestradiol (EE2), and diethylstilbestrol (DES). Concentrated animal feedlot operations (CAFOs) are of particular concern since large amounts of naturally excreted estrogens are discharged into aquatic environments. This study investigated E2, E1, E3, EE2, and DES with high performance liquid chromatography/tandem mass (HPLC-MS/MS) analyses along Wulo Creek in southern Taiwan, near a concentrated livestock feedlot containing 1,030,000 broiler chickens, 934,000 laying hens, 85,000 pigs, and 1500 cattle. Sampling was performed from December 2008 to May 2009, in which 54 samples were collected. Experimental results indicate that concentrations of EE2 were lower than the limit of detection (LOD), and concentrations of DES were only detected twice. Concentrations ranged from 7.4 to 1267 ng/L for E1, from not detected (ND) to 313.6 ng/L for E2, and from ND to 210 ng/L for E3. E1 had the highest average mass fraction (72.2 + or - 3.6%), which was significantly higher than E3 (16.2 + or - 1.7%) and E2 (11.5 + or - 2.6%). Additionally, the mean E2 equivalent quotient (EEQ) ranged from 17.3 to 137.9 ng-E2/L. Despite having a markedly lower concentration than E1, E2 more significantly contributed (52.4 + or - 6.0%) EEQ than E1 (19.7 + or - 3.5%). Moreover, the concentrations of E2, E1, and E3 upstream were significantly higher than concentrations downstream, suggesting a high attenuation effect and fast degradation in the study water. Most concentrations in winter season were higher than those of spring season due to the low dilution effect and low microbial activity in the winter season. Based on the results of this study, we recommend further treatment of the wastewater discharge from the feedlot.

  6. Fibrinogen concentrate in bleeding patients

    DEFF Research Database (Denmark)

    Wikkelsø, Anne; Lunde, Jens; Johansen, Mathias;

    2013-01-01

    Hypofibrinogenaemia is associated with increased morbidity and mortality, but the optimal treatment level, the use of preemptive treatment and the preferred source of fibrinogen remain disputed. Fibrinogen concentrate is increasingly used and recommended for bleeding with acquired haemostatic...

  7. 10-kilowatt Photovoltaic Concentrator Array

    Energy Technology Data Exchange (ETDEWEB)

    Donovan, R.L.; Broadbent, S.

    1978-05-01

    Martin Marietta has designed a Photovoltaic Concentrator Array (PCA) for Sandia Laboratories, Kirtland AFB, New Mexico. The PCA is based on the use of an acrylic Fresnel lens to concentrate sunlight on high intensity solar cells. The objective of the development was to obtain economical photovoltaic power generation by replacing relatively high priced solar cells with low cost lenses. Consequently, a major task of the program was to optimize the design for minimum cost per unit power output. Major design aspects considered for optimization were the concentration ratio, size and shape of the Fresnel lens, array size and shape, structure minimization, tracking and control and the practical aspects of operation and maintenance. In addition to design of the complete array, several porototype photovoltaic concentrator module subassemblies were fabricated and delivered to Sandia for evaluation. These prototypes exceed the 9.0% efficiency requirement established for this program.

  8. Mitragynine concentrations in two fatalities.

    Science.gov (United States)

    Domingo, Olwen; Roider, Gabriele; Stöver, Andreas; Graw, Matthias; Musshoff, Frank; Sachs, Hans; Bicker, Wolfgang

    2017-02-01

    Two cases of fatalities are reported of which the recreational use of Mitragyna speciosa ("kratom") could be confirmed. One of these cases presents with one of the highest postmortem mitragynine concentrations published to date. Our results show that even extremely high mitragynine blood concentrations following the consumption of kratom do not necessarily have to be the direct cause of death in such fatalities as a result of an acute overdose. The two cases are compared with regard to the differences in mitragynine concentrations detected and the role of mitragynine in the death of the subjects. Irrespective of the big differences in mitragynine concentrations in the postmortem blood samples, mitragynine was not the primary cause of death in either of the two cases reported here. Additionally, by rough estimation, a significant difference in ratio of mitragynine to its diastereomers in the blood and urine samples between the two cases could be seen.

  9. Generalized Entropy Concentration for Counts

    CERN Document Server

    Oikonomou, Kostas N

    2016-01-01

    We consider the phenomenon of entropy concentration under linear constraints in a discrete setting, using the "balls and bins" paradigm, but without the assumption that the number of balls allocated to the bins is known. Therefore instead of \\ frequency vectors and ordinary entropy, we have count vectors with unknown sum, and a certain generalized entropy. We show that if the constraints bound the allowable sums, this suffices for concentration to occur even in this setting. The concentration can be either in terms of deviation from the maximum generalized entropy value, or in terms of the norm of the difference from the maximum generalized entropy vector. Without any asymptotic considerations, we quantify the concentration in terms of various parameters, notably a tolerance on the constraints which ensures that they are always satisfied by an integral vector. Generalized entropy maximization is not only compatible with ordinary MaxEnt, but can also be considered an extension of it, as it allows us to address...

  10. Thermodynamic efficiency of solar concentrators.

    Science.gov (United States)

    Shatz, Narkis; Bortz, John; Winston, Roland

    2010-04-26

    The optical thermodynamic efficiency is a comprehensive metric that takes into account all loss mechanisms associated with transferring flux from the source to the target phase space, which may include losses due to inadequate design, non-ideal materials, fabrication errors, and less than maximal concentration. We discuss consequences of Fermat's principle of geometrical optics and review étendue dilution and optical loss mechanisms associated with nonimaging concentrators. We develop an expression for the optical thermodynamic efficiency which combines the first and second laws of thermodynamics. As such, this metric is a gold standard for evaluating the performance of nonimaging concentrators. We provide examples illustrating the use of this new metric for concentrating photovoltaic systems for solar power applications, and in particular show how skewness mismatch limits the attainable optical thermodynamic efficiency.

  11. Study on Correlation of Several Physical and Chemical Parameters of PolycyclicAromatic Hydrocarbons to Median Lethal Concentration (LC50)%多环芳烃的几种理化参数与LC50的相关性研究

    Institute of Scientific and Technical Information of China (English)

    解静芳; 吴弢; 潘绍先

    2000-01-01

    Studied on four physical and chemical parameters of polycyclic aromatic hydrocarbons (PAHs) (logoctanol-water partition coefficient, solubility in water, molecular connectivity index,relative specific retention vol-ume and the correlative coefficient of LC50, and established four monadic regression equations have been conducted;The results showed that the correlative coefficient of the four parameters, values, rkow, rsw, rx, and rvg(r), were 0.7266,0.8083,0.9488and 0.9570 respectively. and r examination showed a highly significant relativity for the two latters. ComparedLC50 of the seven PAHs, which were estimated by monadic regression equations with the experimental values, theaverage relative errors were 58.84%, 32.23%,17.61% and 19.8% respectively. LC50 was estimated by 1X and Vg(r). Theaccuracy of estimation were 0.1613 and 0.1481 respectively. They are also high. The result of experiment showed thatin order of correlation between four parameters and LC50 were Vg(r)> 1X> Sw > Kow. A new method for estimating LC50 ofPAHs in pseudorasbora parva was also discussed.%对多环芳烃(PAHs)4种理化参数(KOow、Sw、1X、Vg(r),)与LC50的相关关系进行了研究,建立了4种一元线性回归方程。结果表明,4种参数的相关系数分别为:0.7266、0.8083、0.9488、0.9570,经r检验,后两种属高度显著相关。用所建立的一元线性回归方程对7种PAH5的LC50进行估算,估算值与实测值相比,平均相对误差分别为58.84%、32.23%、17.61%、19.8%,用1X和Vg(r) 对LC50进行估算的估算精度也较高。经比较,提出用Vg(r) 估算PAHs对麦穗鱼LC50的新方法。

  12. Additive mixture effects of estrogenic chemicals in human cell-based assays can be influenced by inclusion of chemicals with differing effect profiles.

    Directory of Open Access Journals (Sweden)

    Richard Mark Evans

    Full Text Available A growing body of experimental evidence indicates that the in vitro effects of mixtures of estrogenic chemicals can be well predicted from the estrogenicity of their components by the concentration addition (CA concept. However, some studies have observed small deviations from CA. Factors affecting the presence or observation of deviations could include: the type of chemical tested; number of mixture components; mixture design; and assay choice. We designed mixture experiments that address these factors, using mixtures with high numbers of components, chemicals from diverse chemical groups, assays with different in vitro endpoints and different mixture designs and ratios. Firstly, the effects of mixtures composed of up to 17 estrogenic chemicals were examined using estrogenicity assays with reporter-gene (ERLUX and cell proliferation (ESCREEN endpoints. Two mixture designs were used: 1 a 'balanced' design with components present in proportion to a common effect concentration (e.g. an EC(10 and 2 a 'non-balanced' design with components in proportion to potential human tissue concentrations. Secondly, the individual and simultaneous ability of 16 potential modulator chemicals (each with minimal estrogenicity to influence the assay outcome produced by a reference mixture of estrogenic chemicals was examined. Test chemicals included plasticizers, phthalates, metals, PCBs, phytoestrogens, PAHs, heterocyclic amines, antioxidants, UV filters, musks, PBDEs and parabens. In all the scenarios tested, the CA concept provided a good prediction of mixture effects. Modulation studies revealed that chemicals possessing minimal estrogenicity themselves could reduce (negatively modulate the effect of a mixture of estrogenic chemicals. Whether the type of modulation we observed occurs in practice most likely depends on the chemical concentrations involved, and better information is required on likely human tissue concentrations of estrogens and of potential

  13. Design and development of a high-concentration photovoltaic concentrator

    Energy Technology Data Exchange (ETDEWEB)

    Hodge, R C

    1982-04-01

    The design and development of a high concentration photovoltaic concentrator module is discussed. The design concept described herein incorporates a curved groove domed Fresnel lens, a high concentration etched multiple vertical junction (EMVJ) solar cell and a passively cooled direct-bonded copper cell mount all packaged in a plastic module. Two seven inch diameter 1200x domed Fresnel lenses were fabricated using single point diamond turning technology. Testing at both GE and Sandia confirmed optical transmission efficiencies of over 83%. Samples of the latest available EMVJ cells were mounted and installed, with a domed Fresnel lens, into a prototype module. Subsequent testing demonstrated net lens-cell efficiencies of 10 to 13%. As a result of this program, salient conclusions have been formulated as to this technology.

  14. Chemical avoidance responses of fishes.

    Science.gov (United States)

    Tierney, Keith B

    2016-05-01

    The hydrosphere is a repository for all of our waste and mistakes, be they sewage, garbage, process-affected waters, runoff, and gases. For fish living in environments receiving undesirable inputs, moving away seems an obvious way to avoid harm. While this should occur, there are numerous examples where it will not. The inability to avoid harmful environments may lead to sensory impairments that in turn limit the ability to avoid other dangers or locate benefits. For avoidance to occur, the danger must first be perceived, which may not happen if the fish is 'blinded' in some capacity. Second, the danger must be recognized for what it is, which may also not happen if the fish is cognitively confused or impaired. Third, it is possible that the fish may not be able to leave the area, or worse, learns to prefer a toxic environment. Concerning generating regulations around avoidance, there are two possibilities: that an avoidance threshold be used to set guidelines for effluent release with the intention of driving fishes away; the second is to set a contaminant concentration that would not affect the avoidance or attraction responses to other cues. With the complexities of the modern world in which we release diverse pollutants, from light to municipal effluents full of 1000s of chemicals, to the diversity present in ecosystems, it is impossible to have avoidance data on every stimulus-species combination. Nevertheless, we may be able to use existing avoidance response data to predict the likelihood of avoidance of untested stimuli. Where we cannot, this review includes a framework that can be used to direct new research. This review is intended to collate existing avoidance response data, provide a framework for making decisions in the absence of data, and suggest studies that would facilitate the prediction of risk to fish health in environments receiving intentional and unintentional human-based chemical inputs.

  15. Impact of High Concentration Solutions on Hydraulic Properties of Geosynthetic Clay Liner Materials

    Directory of Open Access Journals (Sweden)

    Lei Liu

    2012-11-01

    Full Text Available This study focuses on the impact of landfill high concentration solutions erosion on geosynthetic clay liner (GCL materials permeability. The permeation tests on the GCL, submerged using different kinds of solutions with different concentrations, were carried out systematically by taking these chemical solutions as permeant liquids. Based on seasonal variations of ion concentrations in Chenjiachong landfill leachate (Wuhan Province, CaCl2, MgCl2, NaCl, and KCl were selected as chemical attack solutions to carry out experimental investigations under three concentrations (50 mM, 100 mM, 200 mM and soak times (5, 10, and 20 days. The variation law of the GCL hydraulic conductivity under different operating conditions was analyzed. The relationship between GCL hydraulic conductivity, chemical solutions categories, concentrations, and soak times were further discussed. The GCL hydraulic conductivity, when soaked and permeated with high concentration chemical solutions, increases several times or exceeds two orders of magnitude, as compared with the permeation test under normal conditions that used water as the permeant liquid. This reveals that GCL is very susceptible to chemical attack. For four chemical solutions, the chemical attack effect on GCL hydraulic conductivity is CaCl2 > MgCl2 > KCl > NaCl. The impact of soak times on GCL hydraulic conductivity is the cooperative contribution of the liner chemical attack reaction and hydration swelling. A longer soak time results in a more advantageous hydration swelling effect. The chemical attack reaction restrains the hydration swelling of the GCL. Moreover, the GCL hydraulic conductivity exponentially decreases with the increased amplitude of thickness.

  16. Concentration variations of several ions in stream after a wildfire

    Institute of Scientific and Technical Information of China (English)

    LIU Yang; HU Hai-qing

    2007-01-01

    In May 2006, a high intensity wildfire occurred in Songling forest region in Daxing'an Mountains, China. The concentration changes of eight ions (K+, Na+, Ca2+, Mg2+, Cl-, Br-, NO3- and SO42-) were measured in burned and unburned streams after fire from May to Oct., 2006. Results show that the most ions flux were higher in burned stream than that in unburned stream during the sampling period, and the greatest concentrations of most ions transported from burned stream occurred in July. After fire, the most amplitude chemical ion was Ca2+, whose average concentration was 5.50 mg·L-1 higher than that in unburned stream, and the total concentration of every chemical ion presents a trend Ca2+> SO42- >Na+> Mg2+> NO3- . The average concentrations of Ca2+, SO42-, Na+ Mg2+, NO3- showed an increase trend,but those of K+, Cl-, Br- had a decreased trend. SO42- had the largest loss among these anions, followed by NO3-. Overall, the increase degree of cation was greater than that of anion after burning.

  17. Soil chemical sensor and precision agricultural chemical delivery system and method

    Energy Technology Data Exchange (ETDEWEB)

    Colburn, J.W. Jr.

    1991-07-23

    A real time soil chemical sensor and precision agricultural chemical delivery system includes a plurality of ground-engaging tools in association with individual soil sensors which measure soil chemical levels. The system includes the addition of a solvent which rapidly saturates the soil/tool interface to form a conductive solution of chemicals leached from the soil. A multivalent electrode, positioned within a multivalent frame of the ground-engaging tool, applies a voltage or impresses a current between the electrode and the tool frame. A real-time soil chemical sensor and controller senses the electrochemical reaction resulting from the application of the voltage or current to the leachate, measures it by resistivity methods, and compares it against pre-set resistivity levels for substances leached by the solvent. Still greater precision is obtained by calibrating for the secondary current impressed through solvent-less soil. The appropriate concentration is then found and the servo-controlled delivery system applies the appropriate amount of fertilizer or agricultural chemicals substantially in the location from which the soil measurement was taken. 5 figures.

  18. Endocrine disrupting chemicals in indoor and outdoor air

    Science.gov (United States)

    Rudel, Ruthann A.; Perovich, Laura J.

    The past 50 years have seen rapid development of new building materials, furnishings, and consumer products and a corresponding explosion in new chemicals in the built environment. While exposure levels are largely undocumented, they are likely to have increased as a wider variety of chemicals came into use, people began spending more time indoors, and air exchange rates decreased to improve energy efficiency. As a result of weak regulatory requirements for chemical safety testing, only limited toxicity data are available for these chemicals. Over the past 15 years, some chemical classes commonly used in building materials, furnishings, and consumer products have been shown to be endocrine disrupting chemicals - that is they interfere with the action of endogenous hormones. These include PCBs, used in electrical equipment, caulking, paints and surface coatings; chlorinated and brominated flame retardants, used in electronics, furniture, and textiles; pesticides, used to control insects, weeds, and other pests in agriculture, lawn maintenance, and the built environment; phthalates, used in vinyl, plastics, fragrances, and other products; alkylphenols, used in detergents, pesticide formulations, and polystyrene plastics; and parabens, used to preserve products like lotions and sunscreens. This paper summarizes reported indoor and outdoor air concentrations, chemical use and sources, and toxicity data for each of these chemical classes. While industrial and transportation-related pollutants have been shown to migrate indoors from outdoor sources, it is expected that indoor sources predominate for these consumer product chemicals; and some studies have identified indoor sources as the predominant factor influencing outdoor ambient air concentrations in densely populated areas. Mechanisms of action, adverse effects, and dose-response relationships for many of these chemicals are poorly understood and no systematic screening of common chemicals for endocrine disrupting

  19. Chemical reactions at aqueous interfaces

    Science.gov (United States)

    Vecitis, Chad David

    2009-12-01

    Interfaces or phase boundaries are a unique chemical environment relative to individual gas, liquid, or solid phases. Interfacial reaction mechanisms and kinetics are often at variance with homogeneous chemistry due to mass transfer, molecular orientation, and catalytic effects. Aqueous interfaces are a common subject of environmental science and engineering research, and three environmentally relevant aqueous interfaces are investigated in this thesis: 1) fluorochemical sonochemistry (bubble-water), 2) aqueous aerosol ozonation (gas-water droplet), and 3) electrolytic hydrogen production and simultaneous organic oxidation (water-metal/semiconductor). Direct interfacial analysis under environmentally relevant conditions is difficult, since most surface-specific techniques require relatively `extreme' conditions. Thus, the experimental investigations here focus on the development of chemical reactors and analytical techniques for the completion of time/concentration-dependent measurements of reactants and their products. Kinetic modeling, estimations, and/or correlations were used to extract information on interfacially relevant processes. We found that interfacial chemistry was determined to be the rate-limiting step to a subsequent series of relatively fast homogeneous reactions, for example: 1) Pyrolytic cleavage of the ionic headgroup of perfluorooctanesulfonate (PFOS) and perfluorooctanoate (PFOA) adsorbed to cavitating bubble-water interfaces during sonolysis was the rate-determining step in transformation to their inorganic constituents carbon monoxide, carbon dioxide, and fluoride; 2) ozone oxidation of aqueous iodide to hypoiodous acid at the aerosol-gas interface is the rate-determining step in the oxidation of bromide and chloride to dihalogens; 3) Electrolytic oxidation of anodic titanol surface groups is rate-limiting for the overall oxidation of organics by the dichloride radical. We also found chemistry unique to the interface, for example: 1

  20. The Use of Chemical-Chemical Interaction and Chemical Structure to Identify New Candidate Chemicals Related to Lung Cancer.

    Directory of Open Access Journals (Sweden)

    Lei Chen

    Full Text Available Lung cancer causes over one million deaths every year worldwide. However, prevention and treatment methods for this serious disease are limited. The identification of new chemicals related to lung cancer may aid in disease prevention and the design of more effective treatments. This study employed a weighted network, constructed using chemical-chemical interaction information, to identify new chemicals related to two types of lung cancer: non-small lung cancer and small-cell lung cancer. Then, a randomization test as well as chemical-chemical interaction and chemical structure information were utilized to make further selections. A final analysis of these new chemicals in the context of the current literature indicates that several chemicals are strongly linked to lung cancer.

  1. Environmental and chemical carcinogenesis.

    Science.gov (United States)

    Wogan, Gerald N; Hecht, Stephen S; Felton, James S; Conney, Allan H; Loeb, Lawrence A

    2004-12-01

    People are continuously exposed exogenously to varying amounts of chemicals that have been shown to have carcinogenic or mutagenic properties in experimental systems. Exposure can occur exogenously when these agents are present in food, air or water, and also endogenously when they are products of metabolism or pathophysiologic states such as inflammation. It has been estimated that exposure to environmental chemical carcinogens may contribute significantly to the causation of a sizable fraction, perhaps a majority, of human cancers, when exposures are related to "life-style" factors such as diet, tobacco use, etc. This chapter summarizes several aspects of environmental chemical carcinogenesis that have been extensively studied and illustrates the power of mechanistic investigation combined with molecular epidemiologic approaches in establishing causative linkages between environmental exposures and increased cancer risks. A causative relationship between exposure to aflatoxin, a strongly carcinogenic mold-produced contaminant of dietary staples in Asia and Africa, and elevated risk for primary liver cancer has been demonstrated through the application of well-validated biomarkers in molecular epidemiology. These studies have also identified a striking synergistic interaction between aflatoxin and hepatitis B virus infection in elevating liver cancer risk. Use of tobacco products provides a clear example of cancer causation by a life-style factor involving carcinogen exposure. Tobacco carcinogens and their DNA adducts are central to cancer induction by tobacco products, and the contribution of specific tobacco carcinogens (e.g. PAH and NNK) to tobacco-induced lung cancer, can be evaluated by a weight of evidence approach. Factors considered include presence in tobacco products, carcinogenicity in laboratory animals, human uptake, metabolism and adduct formation, possible role in causing molecular changes in oncogenes or suppressor genes, and other relevant data

  2. Chemical Synthesis of Glycosaminoglycans.

    Science.gov (United States)

    Mende, Marco; Bednarek, Christin; Wawryszyn, Mirella; Sauter, Paul; Biskup, Moritz B; Schepers, Ute; Bräse, Stefan

    2016-07-27

    Glycosaminoglycans (GAGs) as one major part of the glycocalyx are involved in many essential biological cell processes, as well as in many courses of diseases. Because of the potential therapeutic application of GAG polymers, fragments, and also derivatives toward different diseases (e.g., heparin derivatives against Alzheimer's disease), there is a continual growing demand for new chemical syntheses, which suffice the high claim to stereoselectivity and chemoselectivity. This Review summarizes the progress of chemical syntheses of GAGs over the last 10 years. For each class of the glycosaminoglycans-hyaluronan (HA), heparan sulfate/heparin (HS/HP), chondroitin/dermatan sulfate (CS/DS), and keratan sulfate (KS)-mainly novel glycosylation strategies, elongation sequences, and protecting group patterns are discussed, but also (semi)automated syntheses, enzymatic approaches, and functionalizations of synthesized or isolated GAGs are considered.

  3. Chemical Engineering in Space

    Science.gov (United States)

    Lobmeyer, Dennis A.; Meneghelli, Barry; Steinrock, Todd (Technical Monitor)

    2001-01-01

    The aerospace industry has long been perceived as the domain of both physicists and mechanical engineers. This perception has endured even though the primary method of providing the thrust necessary to launch a rocket into space is chemical in nature. The chemical engineering and chemistry personnel behind the systems that provide access to space have labored in the shadows of the physicists and mechanical engineers. As exploration into the cosmos moves farther away from Earth, there is a very distinct need for new chemical processes to help provide the means for advanced space exploration. The state of the art in launch systems uses chemical propulsion systems, primarily liquid hydrogen and liquid oxygen, to provide the energy necessary to achieve orbit. As we move away from Earth, there are additional options for propulsion. Unfortunately, few of these options can compare to the speed or ease of use provided by the chemical propulsion agents. It is with great care and significant cost that gaseous compounds such as hydrogen and oxygen are liquefied and become dense enough to use for rocket fuel. These low-temperature liquids fall within a specialty area known as cryogenics. Cryogenics, the science and art of producing cold operating conditions for use on Earth, in orbit, or on some other nonterrestrial body, has become increasingly important to our ability to travel within our solar system. The production of cryogenic fuels and the long-term storage of these fluids are necessary for travel. As our explorations move farther away from Earth, we need to address how to produce the necessary fuels to make a round-trip. The cost and the size of these expeditions are extreme at best. If we take everything necessary for our survival for the round-trip, we invalidate any chance of travel in the near future. As with the early explorers on Earth, we need to harvest much of our energy and our life support from the celestial bodies. The in situ production of these energy

  4. Chemical genetics and regeneration.

    Science.gov (United States)

    Sengupta, Sumitra; Zhang, Liyun; Mumm, Jeff S

    2015-01-01

    Regeneration involves interactions between multiple signaling pathways acting in a spatially and temporally complex manner. As signaling pathways are highly conserved, understanding how regeneration is controlled in animal models exhibiting robust regenerative capacities should aid efforts to stimulate repair in humans. One way to discover molecular regulators of regeneration is to alter gene/protein function and quantify effect(s) on the regenerative process: dedifferentiation/reprograming, stem/progenitor proliferation, migration/remodeling, progenitor cell differentiation and resolution. A powerful approach for applying this strategy to regenerative biology is chemical genetics, the use of small-molecule modulators of specific targets or signaling pathways. Here, we review advances that have been made using chemical genetics for hypothesis-focused and discovery-driven studies aimed at furthering understanding of how regeneration is controlled.

  5. COOEE bitumen: chemical aging

    CERN Document Server

    Lemarchand, Claire A; Dyre, Jeppe C; Hansen, Jesper S

    2013-01-01

    We study chemical aging in "COOEE bitumen" using molecular dynamic simulations. The model bitumen is composed of four realistic molecule types: saturated hydrocarbon, resinous oil, resin, and asphaltene. The aging reaction is modelled by the chemical reaction: "2 resins $\\rightarrow$ 1 asphaltene". Molecular dynamic simulations of four bitumen compositions, obtained by a repeated application of the aging reaction, are performed. The stress autocorrelation function, the fluid structure, the rotational dynamics of the plane aromatic molecules, and the diffusivity of each molecule, are determined for the four different compositions. The aging reaction causes a significant dynamics slowdown, which is correlated to the aggregation of asphaltene molecules in larger and dynamically slower nanoaggregates. Finally, a detailed description of the role of each molecule types in the aggregation and aging processes is given.

  6. Autocatalytic chemical smoke rings

    CERN Document Server

    Rogers, M C; Rogers, Michael C.; Morris, Stephen W.

    2005-01-01

    Buoyant plumes, evolving free of boundary constraints, may develop well-defined mushroom shaped heads. In normal plumes, overturning flow in the head entrains less buoyant fluid from the surroundings as the head rises, robbing the plume of its driving force. We consider here a new type of plume in which the source of buoyancy is an autocatalytic chemical reaction. The reaction occurs at a sharp front which separates reactants from less dense products. In this type of plume, entrainment assists the reaction, producing new buoyancy which fuels an accelerating plume head. When the head has grown to a critical size, it detaches from the upwelling conduit, forming an accelerating, buoyant vortex ring. This vortex is analogous to a rising smoke ring. A second-generation head then develops at the point of detachment.Multiple generations of chemical vortex rings can detach from a single triggering event.

  7. Biocatalysis for Biobased Chemicals

    Directory of Open Access Journals (Sweden)

    Rubén de Regil

    2013-10-01

    Full Text Available The design and development of greener processes that are safe and friendly is an irreversible trend that is driven by sustainable and economic issues. The use of Biocatalysis as part of a manufacturing process fits well in this trend as enzymes are themselves biodegradable, require mild conditions to work and are highly specific and well suited to carry out complex reactions in a simple way. The growth of computational capabilities in the last decades has allowed Biocatalysis to develop sophisticated tools to understand better enzymatic phenomena and to have the power to control not only process conditions but also the enzyme’s own nature. Nowadays, Biocatalysis is behind some important products in the pharmaceutical, cosmetic, food and bulk chemicals industry. In this review we want to present some of the most representative examples of industrial chemicals produced in vitro through enzymatic catalysis.

  8. Interactive Chemical Reactivity Exploration

    CERN Document Server

    Haag, Moritz P; Bosson, Mael; Redon, Stephane; Reiher, Markus

    2014-01-01

    Elucidating chemical reactivity in complex molecular assemblies of a few hundred atoms is, despite the remarkable progress in quantum chemistry, still a major challenge. Black-box search methods to find intermediates and transition-state structures might fail in such situations because of the high-dimensionality of the potential energy surface. Here, we propose the concept of interactive chemical reactivity exploration to effectively introduce the chemist's intuition into the search process. We employ a haptic pointer device with force-feedback to allow the operator the direct manipulation of structures in three dimensions along with simultaneous perception of the quantum mechanical response upon structure modification as forces. We elaborate on the details of how such an interactive exploration should proceed and which technical difficulties need to be overcome. All reactivity-exploration concepts developed for this purpose have been implemented in the Samson programming environment.

  9. Chemical Decontaminant Testing

    Science.gov (United States)

    2014-10-20

    any other provision of law, no person shall be subject to any penalty for failing to comply with a collection of information if it does not display...Some test methods for efficacy require the use of CWAs and decontaminants. 15. SUBJECT TERMS decontamination; chemical warfare agent; CWA...contaminant in samples from contact samplers , coupons, rinsate, or other samples. MS, GC or LC, FID, FPD, or equivalents. ±15 percent of the mass of

  10. Chemical transport reactions

    CERN Document Server

    Schäfer, Harald

    2013-01-01

    Chemical Transport Reactions focuses on the processes and reactions involved in the transport of solid or liquid substances to form vapor phase reaction products. The publication first offers information on experimental and theoretical principles and the transport of solid substances and its special applications. Discussions focus on calculation of the transport effect of heterogeneous equilibria for a gas motion between equilibrium spaces; transport effect and the thermodynamic quantities of the transport reaction; separation and purification of substances by means of material transport; and

  11. Chemical constituents of Asparagus

    Directory of Open Access Journals (Sweden)

    J S Negi

    2010-01-01

    Full Text Available Asparagus species (family Liliaceae are medicinal plants of temperate Himalayas. They possess a variety of biological properties, such as being antioxidants, immunostimulants, anti-inflammatory, antihepatotoxic, antibacterial, antioxytocic, and reproductive agents. The article briefly reviews the isolated chemical constituents and the biological activities of the plant species. The structural formula of isolated compounds and their distribution in the species studied are also given.

  12. Control of chemical chaos

    Institute of Scientific and Technical Information of China (English)

    李卫东; 钱积新

    2002-01-01

    Lyapunov exponents can act as the judgment rule whether the systems is chaotic or not.We propose an approach to control chaotic systems by varying the Lyapunov exponents of the system. At last we use this method to control a chemical system. Both the theoretical analysis and the simulation results prove that this method can quickly and effectively stabilize the chaotic systems to the desire points.

  13. Gene expression and chemical exposure data for larval Pimephales promelas exposed to one of four pyrethroid pesticides.

    Data.gov (United States)

    U.S. Environmental Protection Agency — Uploaded datasets are detailed exposure information (chemical concentrations and water quality parameters) for exposures conducted in a flow through diluter system...

  14. Combined processing of lead concentrates

    Science.gov (United States)

    Kubasov, V. L.; Paretskii, V. M.; Sidorin, G. N.; Travkin, V. F.

    2013-06-01

    A combined scheme of processing of lead concentrates with the production of pure metallic lead and the important components containing in these concentrates is considered. This scheme includes sulfating roasting of the lead concentrates and two-stage leaching of the formed cinder with the formation of a sulfate solution and lead sulfate. When transformed into a carbonate form, lead sulfate is used for the production of pure metallic lead. Silver, indium, copper, cadmium, nickel, cobalt, and other important components are separately extracted from a solution. At the last stage, zinc is extracted by either extraction followed by electrolytic extraction of a metal or the return of the forming solution of sulfuric acid to cinder leaching.

  15. Chemical Reactions at Surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Michael Henderson and Nancy Ryan Gray

    2010-04-14

    Chemical reactions at surfaces underlie some of the most important processes of today, including catalysis, energy conversion, microelectronics, human health and the environment. Understanding surface chemical reactions at a fundamental level is at the core of the field of surface science. The Gordon Research Conference on Chemical Reactions at Surfaces is one of the premiere meetings in the field. The program this year will cover a broad range of topics, including heterogeneous catalysis and surface chemistry, surfaces in environmental chemistry and energy conversion, reactions at the liquid-solid and liquid-gas interface, electronic materials growth and surface modification, biological interfaces, and electrons and photons at surfaces. An exciting program is planned, with contributions from outstanding speakers and discussion leaders from the international scientific community. The conference provides a dynamic environment with ample time for discussion and interaction. Attendees are encouraged to present posters; the poster sessions are historically well attended and stimulate additional discussions. The conference provides an excellent opportunity for junior researchers (e.g. graduate students or postdocs) to present their work and interact with established leaders in the field.

  16. Metabolomics in chemical ecology.

    Science.gov (United States)

    Kuhlisch, Constanze; Pohnert, Georg

    2015-07-01

    Chemical ecology elucidates the nature and role of natural products as mediators of organismal interactions. The emerging techniques that can be summarized under the concept of metabolomics provide new opportunities to study such environmentally relevant signaling molecules. Especially comparative tools in metabolomics enable the identification of compounds that are regulated during interaction situations and that might play a role as e.g. pheromones, allelochemicals or in induced and activated defenses. This approach helps overcoming limitations of traditional bioassay-guided structure elucidation approaches. But the power of metabolomics is not limited to the comparison of metabolic profiles of interacting partners. Especially the link to other -omics techniques helps to unravel not only the compounds in question but the entire biosynthetic and genetic re-wiring, required for an ecological response. This review comprehensively highlights successful applications of metabolomics in chemical ecology and discusses existing limitations of these novel techniques. It focuses on recent developments in comparative metabolomics and discusses the use of metabolomics in the systems biology of organismal interactions. It also outlines the potential of large metabolomics initiatives for model organisms in the field of chemical ecology.

  17. A Novel Chemical Oscillator with Tyrosine as the Substrate

    Institute of Scientific and Technical Information of China (English)

    Wu YANG; Jie REN; Jin Zhang GAO; Hua YANG; Dong Yu Lü; Xiu Hui LIU

    2003-01-01

    A new chemical oscillating reaction system involving the manganese(II)-catalyzed reaction among potassium bromate, acetone and tyrosine in acidic medium was described in this paper. The apparent activation energy of the induction period (Ein) and that of oscillation period (Ep) were calculated, Ein=110.61KJ/mol, Ep=159.41KJ/mol. The optimum concentration of each reactant was investigated and a steady chemical oscillating system was obtained.

  18. Collaborative Core Research Program for Chemical-Biological Warfare Defense

    Science.gov (United States)

    2015-01-04

    Research Center (UC-DDRC, part of UC-MDI). Using an EvoTec robot , single point (10 μM final solution test chemical concentration) 2 measurements...assay on neuroblastoma cell lines. We performed this method, as well as incorporated a novel method developed at US Army Medical Research Institute of...formulations chemists to determine the optimal dose methods. These new CWA countermeasures will be transitioned to the Chemical Biological Medical Systems for

  19. Flow-Injection Responses of Diffusion Processes and Chemical Reactions

    DEFF Research Database (Denmark)

    Andersen, Jens Enevold Thaulov

    2000-01-01

    The technique of Flow-injection Analysis (FIA), now aged 25 years, offers unique analytical methods that are fast, reliable and consuming an absolute minimum of chemicals. These advantages together with its inherent feasibility for automation warrant the future applications of FIA as an attractive...... be used in the resolution of FIA profiles to obtain information about the content of interference’s, in the study of chemical reaction kinetics and to measure absolute concentrations within the FIA-detector cell....

  20. The Impact of Price on Chemical Fertilizer Demand in China

    Institute of Scientific and Technical Information of China (English)

    John K.Dagsvik

    2012-01-01

    Since 1998,the national policies on chemical fertilizer in China have been concentrated in limiting price plus subsidizing,abolishing agricultural tax,giving direct subsidies to farmers,and other aspects.In order to analyze the impact of national policies on the consumption of chemical fertilizer,this article selects the consumption of chemical fertilizer per unit,chemical fertilizer price index and farmers’net income in different provinces during the period 1998-2007 as variables,to conduct regression analysis of chemical fertilizer expenditure function,and calculate the price elasticity and income elasticity of chemical fertilizer demand in different provinces over the decade based on the regression results.The results show that at present the basic consumption of chemical fertilizer for agricultural development in China is 0.35 t/hm 2 ,and the consumption of chemical fertilizer is excessive in some provinces;the chemical fertilizer market has not been really established,and the price has little impact on demand.This indicates that the chemical fertilizer is essential for agricultural economic development,and it increases along with the increase of farmers’income; the intervention of the national policy in chemical fertilizer price is a fundamental reason for the rising demand for chemical fertilizer.This also to some extent indicates that the policy effect of merely using environmental taxes to change farmers’consumption of chemical fertilizer is limited;there is a need to transform the existing policies purely promoting agricultural economic development,toward giving different subsidies in accordance with whether the farmers’fertilization pattern is beneficial to the environment.

  1. Chemical Reaction Networks for Computing Polynomials.

    Science.gov (United States)

    Salehi, Sayed Ahmad; Parhi, Keshab K; Riedel, Marc D

    2017-01-20

    Chemical reaction networks (CRNs) provide a fundamental model in the study of molecular systems. Widely used as formalism for the analysis of chemical and biochemical systems, CRNs have received renewed attention as a model for molecular computation. This paper demonstrates that, with a new encoding, CRNs can compute any set of polynomial functions subject only to the limitation that these functions must map the unit interval to itself. These polynomials can be expressed as linear combinations of Bernstein basis polynomials with positive coefficients less than or equal to 1. In the proposed encoding approach, each variable is represented using two molecular types: a type-0 and a type-1. The value is the ratio of the concentration of type-1 molecules to the sum of the concentrations of type-0 and type-1 molecules. The proposed encoding naturally exploits the expansion of a power-form polynomial into a Bernstein polynomial. Molecular encoders for converting any input in a standard representation to the fractional representation as well as decoders for converting the computed output from the fractional to a standard representation are presented. The method is illustrated first for generic CRNs; then chemical reactions designed for an example are mapped to DNA strand-displacement reactions.

  2. HANFORD CHEMICAL VAPORS WORKER CONCERNS & EXPOSURE EVALUATION

    Energy Technology Data Exchange (ETDEWEB)

    ANDERSON, T.J.

    2006-12-20

    Chemical vapor emissions from underground hazardous waste storage tanks on the Hanford site in eastern Washington State are a potential concern because workers enter the tank farms on a regular basis for waste retrievals, equipment maintenance, and surveillance. Tank farm contractors are in the process of retrieving all remaining waste from aging single-shell tanks, some of which date to World War II, and transferring it to newer double-shell tanks. During the waste retrieval process, tank farm workers are potentially exposed to fugitive chemical vapors that can escape from tank headspaces and other emission points. The tanks are known to hold more than 1,500 different species of chemicals, in addition to radionuclides. Exposure assessments have fully characterized the hazards from chemical vapors in half of the tank farms. Extensive sampling and analysis has been done to characterize the chemical properties of hazardous waste and to evaluate potential health hazards of vapors at the ground surface, where workers perform maintenance and waste transfer activities. Worker concerns. risk communication, and exposure assessment are discussed, including evaluation of the potential hazards of complex mixtures of chemical vapors. Concentrations of vapors above occupational exposure limits-(OEL) were detected only at exhaust stacks and passive breather filter outlets. Beyond five feet from the sources, vapors disperse rapidly. No vapors have been measured above 50% of their OELs more than five feet from the source. Vapor controls are focused on limited hazard zones around sources. Further evaluations of vapors include analysis of routes of exposure and thorough analysis of nuisance odors.

  3. Capture zone delineation methodology based on the maximum concentration: Preventative groundwater well protection areas for heat exchange fluid mixtures

    Science.gov (United States)

    Okkonen, Jarkko; Neupauer, Roseanna M.

    2016-05-01

    Capture zones of water supply wells are most often delineated based on travel times of water or solute to the well, with the assumption that if the travel time is sufficiently large, the concentration of chemical at the well will not exceed the drinking water standards. In many situations, the likely source concentrations or release masses of contamination from the potential sources are unknown; therefore, the exact concentration at the well cannot be determined. In situations in which the source mass can be estimated with some accuracy, the delineation of the capture zone should be based on the maximum chemical concentration that can be expected at the well, rather than on an arbitrary travel time. We present a new capture zone delineation methodology that is based on this maximum chemical concentration. The method delineates capture zones by solving the adjoint of the advection-dispersion-reaction equation and relating the adjoint state and the known release mass to the expected chemical concentration at the well. We demonstrate the use of this method through a case study in which soil heat exchange systems are potential sources of contamination. The heat exchange fluid mixtures contain known fluid volumes and chemical concentrations; thus, in the event of a release, the release mass of the chemical is known. We also demonstrate the use of a concentration basis in quantifying other measures of well vulnerability including exposure time and time to exceed a predefined threshold concentration at the well.

  4. Concentrado protéico de resíduos da filetagem de tilápia-do-nilo (Oreochromis niloticus: caracterização físico-química e aceitação sensorial Protein concentrate from the residues left after filleting Nile tilapia (Oreochromis niloticus: physical-chemical characterization and sensory acceptance

    Directory of Open Access Journals (Sweden)

    Juliana Maria Aderaldo Vidal

    2011-03-01

    Full Text Available Este estudo objetivou o aproveitamento da carne mecanicamente separada (CMS de resíduos da filetagem de tilápia-do-nilo (Oreochromis niloticus Linnaeus, 1757 na obtenção de um concentrado protéico de tilápia (CPT para o consumo humano, caracterizando-o quanto aos parâmetros físico-químicos e sensoriais. O CPT foi caracterizado quanto aos seguintes aspectos: rendimento, umidade, proteína, gordura, cinzas, atividade de água (Aw e aceitação sensorial. O CPT apresentou rendimento de 18,34%, baixos níveis de umidade e cinza e alto conteúdo protéico e lipídico, quando comparado à matéria-prima original (CMS e baixa Aw. Na avaliação sensorial do CPT, a freqüência de aceitação dos provadores foi de 60,4% para a cor, 51,1% para o aspecto geral e 41,7% para o aroma. A descrição do aroma com termos como característico de pescado foi relatada por 44,2% dos provadores, sugerindo a necessidade de uma desodorização parcial do material, e indicando um equilíbrio em relação ao grupo dos provadores que não perceberam o odor característico. Esta pesquisa mostra agregação de valor a um material de descarte, gerando possibilidades de oferta de uma fonte proteica alternativa, de custo relativamente baixo.This study aimed to use mechanically separated mince (MSM from the residues left after filleting Nile tilapia (Oreochromis niloticus Linnaeus, 1757 to obtain a protein concentrate for human consumption and to assess its proximal composition and sensory characteristics. Yield, proximal composition, water activity and sensory evaluation were analyzed on the dry TPC. The TPC has a yield of 18.34%, and contained 1.38% moisture, 62.39% protein, 32.63% fat, 2.26% ash and had 0.16 Aw. Sensory evaluation of dry FPC powder expressed as frequency of acceptance by panelists was 60.4% for color, 51.1% for general appearance and 41.7% for aroma. Description of flavor using terms like "typical of fish" was reported by only 44.2% of the

  5. Study on Raman spectral imaging method for simultaneous estimation of ingredients concentration in food powder

    Science.gov (United States)

    This study investigated the potential of point scan Raman spectral imaging method for estimation of different ingredients and chemical contaminant concentration in food powder. Food powder sample was prepared by mixing sugar, vanillin, melamine and non-dairy cream at 5 different concentrations in a ...

  6. Removal of two polycyclic musks in sewage treatment plants: Freely dissolved and total concentrations

    NARCIS (Netherlands)

    Artola-Garicano, E.; Borkent, I.; Hermens, J.L.M.; Vaes, W.H.J.

    2003-01-01

    In the current study, the removal of slowly degradable hydrophobic chemicals in sewage treatment plants (STPs) has been evaluated with emphasis on the combination of free and total concentration data. Free and total concentrations of two polycyclic musks were determined in each compartment of four S

  7. Concentration of paramagnetic centres at low-temperature thermal destruction of asphaltenes of heavy petroleum distillates

    Directory of Open Access Journals (Sweden)

    Dolomatov M.U., Rodionov A.A., Gafurov M.R., Petrov A.V., Biktagirov T.B., Bakhtizin R.Z., Makarchikov S.O., Khairudinov I.Z., Orlinskii S.B.

    2016-11-01

    Full Text Available Changes of paramagnetic centers (PC concentration in dispersed petroleum systems were studied in the process of low-temperature thermolysis. The kinetic model of PC concentration dynamics based on the processes of unpaired electrons formation during singlet-triplet transitions, weak chemical bonds dissociation and recombination of free radicals is proposed.

  8. Scientific substantination of maximum allowable concentration of fluopicolide in water

    Directory of Open Access Journals (Sweden)

    Pelo I.М.

    2014-03-01

    Full Text Available In order to substantiate fluopicolide maximum allowable concentration in the water of water reservoirs the research was carried out. Methods of study: laboratory hygienic experiment using organoleptic and sanitary-chemical, sanitary-toxicological, sanitary-microbiological and mathematical methods. The results of fluopicolide influence on organoleptic properties of water, sanitary regimen of reservoirs for household purposes were given and its subthreshold concentration in water by sanitary and toxicological hazard index was calculated. The threshold concentration of the substance by the main hazard criteria was established, the maximum allowable concentration in water was substantiated. The studies led to the following conclusions: fluopicolide threshold concentration in water by organoleptic hazard index (limiting criterion – the smell – 0.15 mg/dm3, general sanitary hazard index (limiting criteria – impact on the number of saprophytic microflora, biochemical oxygen demand and nitrification – 0.015 mg/dm3, the maximum noneffective concentration – 0.14 mg/dm3, the maximum allowable concentration - 0.015 mg/dm3.

  9. Segmented holographic spectrum splitting concentrator

    Science.gov (United States)

    Ayala, Silvana P.; Vorndran, Shelby; Wu, Yuechen; Chrysler, Benjamin; Kostuk, Raymond K.

    2016-09-01

    This paper presents a segmented parabolic concentrator employing holographic spectral filters that provide focusing and spectral bandwidth separation capability to the system. Strips of low band gap silicon photovoltaic (PV) cells are formed into a parabolic surface as shown by Holman et. al. [1]. The surface of the PV segments is covered with holographic elements formed in dichromated gelatin. The holographic elements are designed to transmit longer wavelengths to silicon cells, and to reflect short wavelength light towards a secondary collector where high-bandgap PV cells are mounted. The system can be optimized for different combinations of diffuse and direct solar illumination conditions for particular geographical locations by controlling the concentration ratio and filtering properties of the holographic elements. In addition, the reflectivity of the back contact of the silicon cells is used to increase the optical path length and light trapping. This potentially allows the use of thin film silicon for the low bandgap PV cell material. The optical design combines the focusing properties of the parabolic concentrator and the holographic element to control the concentration ratio and uniformity of the spectral distribution at the high bandgap cell location. The presentation concludes with a comparison of different spectrum splitting holographic filter materials for this application.

  10. Biodegradation kinetics at low concentrations (

    DEFF Research Database (Denmark)

    Toräng, Lars; Albrechtsen, Hans-Jørgen; Nyholm, Niels

    2000-01-01

    Aerobic biodegradation of 2,4-dichlorophenoxyacetic acid (2,4-D) was studied in groundwater added sediment fines. At concentrations at or below 1 mu g/L of 2,4-D degradation kinetic was of true first order without significant growth of specific degraders and with half-life for mineralization...

  11. Benign concentric annular macular dystrophy

    Directory of Open Access Journals (Sweden)

    Luísa Salles de Moura Mendonça

    2015-06-01

    Full Text Available The purpose of the authors is to show clinical findings of a patient with benign concentric annular macular dystrophy, which is an unusual condition, and part of the "bull’s eye" maculopathy differential diagnosis. An ophthalmologic examination with color perception, fluorescein angiography, and ocular electrophysiology was performed.

  12. Gravimetric determination of phospholipid concentration.

    Science.gov (United States)

    Tejera-Garcia, Roberto; Connell, Lisa; Shaw, Walter A; Kinnunen, Paavo K J

    2012-09-01

    Accurate determination of lipid concentrations is an obligatory routine in a research laboratory engaged in studies using this class of biomaterials. For phospholipids, this is frequently accomplished using the phosphate assay (Bartlett, G.R. Phosphorus Assay in Column Chromatography. J. Biol. Chem. 234, 466-468, 1959). Given the purity of the currently commercially available synthetic and isolated natural lipids, we have observed that determination of the dry weight of lipid stock solutions provides the fastest, most accurate, and generic method to assay their concentrations. The protocol described here takes advantage of the high resolution and accuracy obtained by modern weighing technology. We assayed by this technique the concentrations of a number of phosphatidylcholine samples, with different degrees of acyl chain saturation and length, and in different organic solvents. The results were compared with those from Bartlett assay, (31)P NMR, and Langmuir compression isotherms. The data obtained show that the gravimetric assay yields lipid concentrations with a resolution similar or better than obtained by the other techniques.

  13. City scale pollen concentration variability

    Science.gov (United States)

    van der Molen, Michiel; van Vliet, Arnold; Krol, Maarten

    2016-04-01

    Pollen are emitted in the atmosphere both in the country-side and in cities. Yet the majority of the population is exposed to pollen in cities. Allergic reactions may be induced by short-term exposure to pollen. This raises the question how variable pollen concentration in cities are in temporally and spatially, and how much of the pollen in cities are actually produced in the urban region itself. We built a high resolution (1 × 1 km) pollen dispersion model based on WRF-Chem to study a city's pollen budget and the spatial and temporal variability in concentration. It shows that the concentrations are highly variable, as a result of source distribution, wind direction and boundary layer mixing, as well as the release rate as a function of temperature, turbulence intensity and humidity. Hay Fever Forecasts based on such high resolution emission and physical dispersion modelling surpass traditional hay fever warning methods based on temperature sum methods. The model gives new insights in concentration variability, personal and community level exposure and prevention. The model will be developped into a new forecast tool to serve allergic people to minimize their exposure and reduce nuisance, coast of medication and sick leave. This is an innovative approach in hay fever warning systems.

  14. Lightweight autonomous chemical identification system (LACIS)

    Science.gov (United States)

    Lozos, George; Lin, Hai; Burch, Timothy

    2012-06-01

    Smiths Detection and Intelligent Optical Systems have developed prototypes for the Lightweight Autonomous Chemical Identification System (LACIS) for the US Department of Homeland Security. LACIS is to be a handheld detection system for Chemical Warfare Agents (CWAs) and Toxic Industrial Chemicals (TICs). LACIS is designed to have a low limit of detection and rapid response time for use by emergency responders and could allow determination of areas having dangerous concentration levels and if protective garments will be required. Procedures for protection of responders from hazardous materials incidents require the use of protective equipment until such time as the hazard can be assessed. Such accurate analysis can accelerate operations and increase effectiveness. LACIS is to be an improved point detector employing novel CBRNE detection modalities that includes a militaryproven ruggedized ion mobility spectrometer (IMS) with an array of electro-resistive sensors to extend the range of chemical threats detected in a single device. It uses a novel sensor data fusion and threat classification architecture to interpret the independent sensor responses and provide robust detection at low levels in complex backgrounds with minimal false alarms. The performance of LACIS prototypes have been characterized in independent third party laboratory tests at the Battelle Memorial Institute (BMI, Columbus, OH) and indoor and outdoor field tests at the Nevada National Security Site (NNSS). LACIS prototypes will be entering operational assessment by key government emergency response groups to determine its capabilities versus requirements.

  15. Radioiodine concentrated in a wetland.

    Science.gov (United States)

    Kaplan, Daniel I; Zhang, Saijin; Roberts, Kimberly A; Schwehr, Kathy; Xu, Chen; Creeley, Danielle; Ho, Yi-Fang; Li, Hsiu-Ping; Yeager, Chris M; Santschi, Peter H

    2014-05-01

    Most subsurface environmental radioactivity contamination is expected to eventually resurface in riparian zones, or wetlands. There are a number of extremely sharp biogeochemical interfaces in wetlands that could alter radionuclide speciation and promote accumulation. The objective of this study was to determine if a wetland concentrated (129)I emanating from a former waste disposal basin located on the Savannah River Site (SRS) in South Carolina, USA. Additionally, studies were conducted to evaluate the role of sediment organic matter in immobilizing the radioiodine. Groundwater samples were collected along a 0.7-km transect away from the seepage basin and in the downstream wetlands. The samples were analyzed for (129)I speciation (iodide (I(-)), iodate (IO3(-)), and organo-I). Groundwater (129)I concentrations in many locations in the wetlands (as high as 59.9 Bq L(-1)(129)I) were greatly elevated with respect to the source term (5.9 Bq L(-1)(129)I). (129)I concentration profiles in sediment cores were closely correlated to organic matter concentrations (r(2) = 0.992; n = 5). While the sediment organic matter promoted the uptake of (129)I to the wetland sediment, it also promoted the formation of a soluble organic fraction: 74% of the wetland groundwater (129)I could pass through a 1 kDa (wetlands may be highly effective at immobilizing aqueous (129)I, they may also promote the formation of a low-molecular-weight organic species that does not partition to sediments. This study provides a rare example of radioactivity concentrations increasing rather than decreasing as it migrates from a point source and brings into question assumptions in risk models regarding continuous dilution of released contaminants.

  16. Tier II Chemical Storage Facilities

    Data.gov (United States)

    Iowa State University GIS Support and Research Facility — Facilities that store hazardous chemicals above certain quantities must submit an annual emergency and hazardous chemical inventory on a Tier II form. This is a...

  17. Fiber Bragg distributed chemical sensor

    NARCIS (Netherlands)

    Boersma, A.; Cheng, L.K.; Jansen, T.H.

    2010-01-01

    A distributed chemical sensor is developed by coating multiple Bragg gratings in a fibre with chemical selective responsive coatings. The optical response of the coated grating is optimised and the recoat process is very reproducible.

  18. Stochastic processes in chemical physics

    CERN Document Server

    Shuler, K E

    2009-01-01

    The Advances in Chemical Physics series provides the chemical physics and physical chemistry fields with a forum for critical, authoritative evaluations of advances in every area of the discipline. Filled with cutting-edge research reported in a cohesive manner not found elsewhere in the literature, each volume of the Advances in Chemical Physics series serves as the perfect supplement to any advanced graduate class devoted to the study of chemical physics.

  19. Cellular biosensing: chemical and genetic approaches.

    Science.gov (United States)

    Haruyama, Tetsuya

    2006-05-24

    Biosensors have been developed to determine the concentration of specific compounds in situ. They are already widely employed as a practical technology in the clinical and healthcare fields. Recently, another concept of biosensing has been receiving attention: biosensing for the evaluation of molecular potency. The development of this novel concept has been supported by the development of related technologies, as such as molecular design, molecular biology (genetic engineering) and cellular/tissular engineering. This review is addresses this new concept of biosensing and its application to the evaluation of the potency of chemicals in biological systems, in the field of cellular/tissular engineering. Cellular biosensing may provide information on both pharmaceutical and chemical safety, and on drug efficacy in vitro as a screening tool.

  20. Chemical and thermal unfolding of calreticulin.

    Science.gov (United States)

    Duus, K; Larsen, N; Tran, T A T; Güven, E; Skov, L K; Jespersgaard, C; Gajhede, M; Houen, G

    2013-05-01

    Calreticulin is a soluble endoplasmic reticulum chaperone, which has a relatively low melting point due to its remarkable structure with a relatively high content of flexible structural elements. Using far ultraviolet circular dichroism (CD) spectroscopy and a fluorescent dye binding thermal shift assay, we have investigated the chemical and thermal stability of calreticulin. When the chemical stability of calreticulin was assessed, a midpoint for calreticulin unfolding was calculated to 3.0M urea using CD data at 222 nm. Using the fluorescent dye binding thermal shift assay, calreticulin was found to obtain a molten structure in urea concentrations between 1-1.5 M urea, and to unfold/aggregate at high and low pH values. The results demonstrated that the fluorescent dye binding assay could measure the thermal stability of calreticulin in aqueous buffers with results comparable to melting points obtained by other techniques.