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Sample records for volatiles largely determine

  1. Emission rate estimates determined for a large number of volatile organic compounds using airborne measurements for the oil sands facilities in Alberta, Canada

    Science.gov (United States)

    Li, S. M.; Leithead, A.; Moussa, S.; Liggio, J.; Moran, M. D.; Wang, D. K.; Hayden, K. L.; Darlington, A.; Gordon, M.; Staebler, R. M.; Makar, P.; Stroud, C.; McLaren, R.; Liu, P.; O'brien, J.; Mittermeier, R. L.; Zhang, J.; Marson, G.; Cober, S.; Wolde, M.; Wentzell, J.

    2016-12-01

    In August and September of 2013, aircraft-based measurements of air pollutants were made during a field campaign in support of the Joint Canada-Alberta Implementation Plan on Oil Sands Monitoring in Alberta, Canada. Volatile organic compounds (VOCs) were determined using a high resolution proton-transfer-reaction time-of-flight mass spectrometer (PTR-ToF-MS) continuously at 2-5 second resolution during the flights, and from 680 discretely sampled stainless steel canisters collected during flights followed by offline GC-MS and GC-FID analyses for four large oil sands surface mining facilities. The Top-down Emission Rate Retrieval Algorithm (TERRA), developed at Environment and Climate Change Canada (ECCC), was applied to the aromatics and oxygenated VOC results from the PTR-ToF-MS to determine their emission rates. Additional VOC species, determined in the canisters, were compared with the PTR-ToF-MS VOC species to determine their emission ratios. Using these emission ratios and the emission rates for the aromatics and oxygenated VOCs, the individual emission rates for 73-90 volatile organic compounds (VOCs) were determined for each of the four major oil sands facilities. The results are the first independently determined emission rates for a large number of VOCs at the same time for large industrial complexes such as the oil sands mining facilities. These measurement-based emission data will be important for strengthening VOC emission reporting.

  2. Volatility jumps and their economic determinants

    DEFF Research Database (Denmark)

    Caporin, Massimiliano; Rossi, Eduardo; Santucci de Magistris, Paolo

    that there is a positive probability of jumps in volatility. A common factor in the volatility jumps is shown to be related to a set of financial covariates (such as variance risk premium, S&P500 volume, credit-default swap, and federal fund rates). The credit-default swap on US banks and variance risk premium have...... predictive power on expected jump moves, thus confirming the common interpretation that sudden and large increases in equity volatility can be anticipated by credit deterioration of the US bank sector as well as changes in the market expectations of future risks. Finally, the model is extended to incorporate...... the credit-default swap and the variance risk premium in the dynamics of the jump size and intensity....

  3. Understanding the determinants of volatility clustering in terms of stationary Markovian processes

    Science.gov (United States)

    Miccichè, S.

    2016-11-01

    Volatility is a key variable in the modeling of financial markets. The most striking feature of volatility is that it is a long-range correlated stochastic variable, i.e. its autocorrelation function decays like a power-law τ-β for large time lags. In the present work we investigate the determinants of such feature, starting from the empirical observation that the exponent β of a certain stock's volatility is a linear function of the average correlation of such stock's volatility with all other volatilities. We propose a simple approach consisting in diagonalizing the cross-correlation matrix of volatilities and investigating whether or not the diagonalized volatilities still keep some of the original volatility stylized facts. As a result, the diagonalized volatilities result to share with the original volatilities either the power-law decay of the probability density function and the power-law decay of the autocorrelation function. This would indicate that volatility clustering is already present in the diagonalized un-correlated volatilities. We therefore present a parsimonious univariate model based on a non-linear Langevin equation that well reproduces these two stylized facts of volatility. The model helps us in understanding that the main source of volatility clustering, once volatilities have been diagonalized, is that the economic forces driving volatility can be modeled in terms of a Smoluchowski potential with logarithmic tails.

  4. Determination of non-volatile and volatile organic acids in Korean traditional fermented soybean paste (Doenjang).

    Science.gov (United States)

    Shukla, Shruti; Choi, Tae Bong; Park, Hae-Kyong; Kim, Myunghee; Lee, In Koo; Kim, Jong-Kyu

    2010-01-01

    Organic acids are formed in food as a result of metabolism of large molecular mass compounds. These organic acids play an important role in the taste and aroma of fermented food products. Doenjang is a traditional Korean fermented soybean paste product that provides a major source of protein. The quantitative data for volatile and non-volatile organic acid contents of 18 samples of Doenjang were determined by comparing the abundances of each peak by gas (GC) and high performance liquid chromatography (HPLC). The mean values of volatile organic acids (acetic acid, butyric acid, propionic acid and 3-methyl butanoic acid), determined in 18 Doenjang samples, were found to be 91.73, 29.54, 70.07 and 19.80 mg%, respectively, whereas the mean values of non-volatile organic acids, such as oxalic acid, citric acid, lactic acid and succinic acid, were noted to be 14.69, 5.56, 9.95 and 0.21 mg%, respectively. Malonic and glutaric acids were absent in all the tested samples of Doenjang. The findings of this study suggest that determination of organic acid contents by GC and HPLC can be considered as an affective approach to evaluate the quality characteristics of fermented food products.

  5. Milk Price Volatility and its Determinants

    OpenAIRE

    Dong, Fengxia; Du, Xiaodong; Gould, Brian W.

    2011-01-01

    The classified pricing of fluid milk under the Federal Milk Marketing Orders (FMMO) system combined with the cash settlement feature of Class IIII milk futures contracts generate a unique volatility pattern of these futures markets in the sense that the volatility gradually decreases as the USDA price announcement dates approaching in the month. Focusing on the evolution of volatility in Class III milk futures market, this study quantifies the relative importance of a set of factors driving m...

  6. The Determinants of Public Deficit Volatility

    OpenAIRE

    2009-01-01

    This paper empirically analyzes the political, institutional and economic sources of public deficit volatility. Using the system-GMM estimator for linear dynamic panel data models and a sample of 125 countries analyzed from 1980 to 2006, we show that higher public deficit volatility is typically associated with higher levels of political instability and less democracy. In addition, public deficit volatility tends to be magnified for small countries, in the outcome of hyper-inflation episodes ...

  7. Volatility Determination in an Ambit Process Setting

    DEFF Research Database (Denmark)

    Barndorff-Nielsen, Ole; Graversen, Svend-Erik

    The probability limit behaviour of normalised quadratic variation is studied for a simple tempo-spatial ambit process, with particular regard to the question of volatility memorylessness.......The probability limit behaviour of normalised quadratic variation is studied for a simple tempo-spatial ambit process, with particular regard to the question of volatility memorylessness....

  8. A large source of low-volatility secondary organic aerosol.

    Science.gov (United States)

    Ehn, Mikael; Thornton, Joel A; Kleist, Einhard; Sipilä, Mikko; Junninen, Heikki; Pullinen, Iida; Springer, Monika; Rubach, Florian; Tillmann, Ralf; Lee, Ben; Lopez-Hilfiker, Felipe; Andres, Stefanie; Acir, Ismail-Hakki; Rissanen, Matti; Jokinen, Tuija; Schobesberger, Siegfried; Kangasluoma, Juha; Kontkanen, Jenni; Nieminen, Tuomo; Kurtén, Theo; Nielsen, Lasse B; Jørgensen, Solvejg; Kjaergaard, Henrik G; Canagaratna, Manjula; Maso, Miikka Dal; Berndt, Torsten; Petäjä, Tuukka; Wahner, Andreas; Kerminen, Veli-Matti; Kulmala, Markku; Worsnop, Douglas R; Wildt, Jürgen; Mentel, Thomas F

    2014-02-27

    Forests emit large quantities of volatile organic compounds (VOCs) to the atmosphere. Their condensable oxidation products can form secondary organic aerosol, a significant and ubiquitous component of atmospheric aerosol, which is known to affect the Earth's radiation balance by scattering solar radiation and by acting as cloud condensation nuclei. The quantitative assessment of such climate effects remains hampered by a number of factors, including an incomplete understanding of how biogenic VOCs contribute to the formation of atmospheric secondary organic aerosol. The growth of newly formed particles from sizes of less than three nanometres up to the sizes of cloud condensation nuclei (about one hundred nanometres) in many continental ecosystems requires abundant, essentially non-volatile organic vapours, but the sources and compositions of such vapours remain unknown. Here we investigate the oxidation of VOCs, in particular the terpene α-pinene, under atmospherically relevant conditions in chamber experiments. We find that a direct pathway leads from several biogenic VOCs, such as monoterpenes, to the formation of large amounts of extremely low-volatility vapours. These vapours form at significant mass yield in the gas phase and condense irreversibly onto aerosol surfaces to produce secondary organic aerosol, helping to explain the discrepancy between the observed atmospheric burden of secondary organic aerosol and that reported by many model studies. We further demonstrate how these low-volatility vapours can enhance, or even dominate, the formation and growth of aerosol particles over forested regions, providing a missing link between biogenic VOCs and their conversion to aerosol particles. Our findings could help to improve assessments of biosphere-aerosol-climate feedback mechanisms, and the air quality and climate effects of biogenic emissions generally.

  9. Rapid volatile metabolomics and genomics in large strawberry populations segregating for aroma

    Science.gov (United States)

    Volatile organic compounds (VOCs) in strawberry (Fragaria spp.) represent a large portion of the fruit secondary metabolome, and contribute significantly to aroma, flavor, disease resistance, pest resistance and overall fruit quality. Understanding the basis for volatile compound biosynthesis and it...

  10. ANALYSIS OF MACROECONOMIC DETERMINANTS OF EXCHANGE RATE VOLATILITY IN INDIA

    Directory of Open Access Journals (Sweden)

    Anita Mirchandani

    2013-01-01

    Full Text Available The Foreign Exchange Market in India has undergone substantial changes over last decade. It is imperative by the excessive volatility of Indian Rupee causing its depreciation against major dominating currencies in international market. This research has been carried out in order to investigate various macroeconomic variables leading to acute variations in the exchange rate of a currency. An attempt has been made to review the probable reasons for the depreciation of the Rupee and analyse different macroeconomic determinants that have impact on the volatility of exchange rate and their extent of correlation with the same.

  11. SPECIFYING THE EFFECTIVE DETERMINANTS OF HOUSE PRICE VOLATILITIES IN IRAN

    Directory of Open Access Journals (Sweden)

    Murteza Sanjarani Pour

    2013-11-01

    Full Text Available The housing sector is one of the key sectors in an economy and its fluctuations could be accompanied with stagnation or expansion in other parts of an economy. Additionally, this sector has an intra-economic role in near to 120 sub-industries which therefore indicates its importance in an economy. Hence, this study examines the effective determinants of house price volatilities using the Engel Granger co-integration technique after modeling the price volatilities under the E-Garch model for the period 1973-2008 in Iran based on Eviews and Mathematica Software. The findings indicate that all variables, including coin price, GDP proxy, volume of money, inflation rate, and house interest rate have a significant impact on the volatilities.

  12. Relaxation dynamics of aftershocks after large volatility shocks in the SSEC index

    Science.gov (United States)

    Mu, Guo-Hua; Zhou, Wei-Xing

    2008-09-01

    The relaxation dynamics of aftershocks after large volatility shocks are investigated based on two high-frequency data sets of the Shanghai Stock Exchange Composite (SSEC) index. Compared with previous relevant work, we have defined main financial shocks based on large volatilities rather than large crashes. We find that the occurrence rate of aftershocks with the magnitude exceeding a given threshold for both daily volatility (constructed using 1-minute data) and minutely volatility (using intra-minute data) decays as a power law. The power-law relaxation exponent increases with the volatility threshold and is significantly greater than 1. Taking financial volatility as the counterpart of seismic activity, the power-law relaxation in financial volatility deviates remarkably from the Omori law in Geophysics.

  13. Microbial production of volatile sulphur compounds in the large intestine of pigs fed two different diets

    DEFF Research Database (Denmark)

    Poulsen, Henrik Vestergaard; Jensen, Bent Borg; Finster, Kai

    2012-01-01

    Aims: To investigate the production of volatile sulphur compounds (VSC) in segments of the large intestine of pigs and to assess the impact of diet on this production. Methods and Results: Pigs were fed two diets based on either wheat and barley (STD) or wheat and dried distillers grains with sol......Aims: To investigate the production of volatile sulphur compounds (VSC) in segments of the large intestine of pigs and to assess the impact of diet on this production. Methods and Results: Pigs were fed two diets based on either wheat and barley (STD) or wheat and dried distillers grains...... significantly higher in the STD group. Conversely, the net methanethiol production rate was significantly higher in the DDGS-group, while no difference was observed for dimethyl sulphide. The number of sulphate reducing bacteria and total bacteria were determined by quantitative PCR and showed a significant...

  14. Optimized determination of trace jet fuel volatile organic compounds in human blood using in-field liquid-liquid extraction with subsequent laboratory gas chromatographic-mass spectrometric analysis and on-column large-volume injection.

    Science.gov (United States)

    Liu, S; Pleil, J D

    2001-03-05

    A practical and sensitive method to assess volatile organic compounds (VOCs) from JP-8 jet fuel in human whole blood was developed by modifying previously established liquid-liquid extraction procedures, optimizing extraction times, solvent volume, specific sample processing techniques, and a new on-column large-volume injection method for GC-MS analysis. With the optimized methods, the extraction efficiency was improved by 4.3 to 20.1 times and the detection sensitivity increased up to 660 times over the standard method. Typical detection limits in the parts-per-trillion (ppt) level range were achieved for all monitored JP-8 constituents; this is sufficient for assessing human fuels exposures at trace environmental levels as well as occupational exposure levels. The sample extractions are performed in the field and only solvent extracts need to be shipped to the laboratory. The method is implemented with standard biological laboratory equipment and a modest bench-top GC-MS system.

  15. [Generic method for determination of volatile organic solvents in cosmetics].

    Science.gov (United States)

    Da, Jing; Huang, Xianglu; Wang, Gangli; Cao, Jin; Zhang, Qingsheng

    2014-11-01

    A generic screening, confirmation and determination method was established based on 36 commonly used volatile organic solvents in cosmetics by headspace gas chromatography- mass spectrometry (GC-MS). This method included a database for pilot screening and identifi- cation of those solvents and their quantitative method. Pilot screening database was composed by two sections, one was household section built by two columns with opposite polarities (col- umn VF-1301 ms and DB-5 ms) using retention index in different column systems as qualitative parameter, and the other was NIST MS search version 2.0. Meanwhile, the determination method of the 36 volatile solvents was developed with GC-MS. Cosmetic samples were dissolved in water and transferred to a headspace vial. After 30 min equilibration at 60 °C, the samples were analyzed by GC-MS equipped with a capillary chromatographic column VF-1301 ms. The external calibration was used for quantification. The limits of detection were from 0.01 to 3.3 μg/g, and the recoveries were from 60.77% to 126.6%. This study provided a generic method for pilot screening, identification, and quantitation of volatile organic solvents in cosmetics, and may solve the problem that different analytical methods need to be developed for different targeted compounds and pilot screening for potential candidate solvent residues.

  16. Determination of Volatile Organic Compounds in Selected Strains of Cyanobacteria

    Directory of Open Access Journals (Sweden)

    Ivan Milovanović

    2015-01-01

    Full Text Available Microalgal biomass can be used in creating various functional food and feed products, but certain species of microalgae and cyanobacteria are known to produce various compounds causing off-flavour. In this work, we investigated selected cyanobacterial strains of Spirulina, Anabaena, and Nostoc genera originating from Serbia, with the aim of determining the chemical profile of volatile organic compounds produced by these organisms. Additionally, the influence of nitrogen level during growth on the production of volatile compounds was investigated for Nostoc and Anabaena strains. In addition, multivariate techniques, namely, principal component analysis (PCA and hierarchical cluster analysis (HCA, were used for making distinction among different microalgal strains. The results show that the main volatile compounds in these species are medium chain length alkanes, but other odorous compounds such as 2-methylisoborneol (0.51–4.48%, 2-pentylfuran (0.72–8.98%, β-cyclocitral (0.00–1.17%, and β-ionone (1.15–2.72% were also detected in the samples. Addition of nitrogen to growth medium was shown to negatively affect the production of 2-methylisoborneol, while geosmin was not detected in any of the analyzed samples, which indicates that the manipulation of growth conditions may be useful in reducing levels of some unwanted odor-causing components.

  17. OPTIMIZED DETERMINATION OF TRACE JET FUEL VOLATILE ORGANIC COMPOUNDS IN HUMAN BLOOD USING IN-FIELD LIQUID-LIQUID EXTRACTION WITH SUBSEQUENT LABORATORY GAS CHROMATOGRAPHIC-MASS SPECTROMETRIC ANALYSIS AND ON-COLUMN LARGE VOLUME INJECTION

    Science.gov (United States)

    A practical and sensitive method to assess volatile organic compounds (VOCs) from JP-8 jet fuel in human whole blood was developed by modifying previously established liquid-liquid extraction procedures, optimizing extraction times, solvent volume, specific sample processing te...

  18. Volatility transmission between small and large caps in the Brazilian market

    Directory of Open Access Journals (Sweden)

    Marcelo Brutti Righi

    2014-04-01

    Full Text Available Researches about volatility transmission between small and large company stocks had received great attention in last years. Based on this idea, the current paper aims to analyze the occurrence of volatility transmission between small and large companies in Brazil. To that, we estimate multivariate GARCH models. As asset proxies we used the Small and Mid-Large cap BM&F/Bovespa index. Results allow concluding that large company stocks impact the small stocks conditional volatility. However, the relationship does not maintain it in reverse direction. This result is in accord with the addressed subject.

  19. A large source of low-volatility secondary organic aerosol

    DEFF Research Database (Denmark)

    Ehn, Mikael; Thornton, Joel A.; Kleist, Einhard

    2014-01-01

    at significant mass yield in the gas phase and condense irreversibly onto aerosol surfaces to produce secondary organic aerosol, helping to explain the discrepancy between the observed atmospheric burden of secondary organic aerosol and that reported by many model studies. We further demonstrate how these low......-volatility vapours can enhance, or even dominate, the formation and growth of aerosol particles over forested regions, providing a missing link between biogenic VOCs and their conversion to aerosol particles. Our findings could help to improve assessments of biosphere-aerosol-climate feedback mechanisms, and the air...

  20. Low-Frequency Volatility in China’s Gold Futures Market and Its Macroeconomic Determinants

    Directory of Open Access Journals (Sweden)

    Song Liu

    2015-01-01

    Full Text Available We extract low- and high-frequency volatility from China’s Shanghai gold futures market using an asymmetric Spline-GARCH (ASP-GARCH model. We then regress monthly low-frequency volatility on selected monthly macroeconomic indicators to study the impact of macroeconomy on gold futures market and to test for excess volatility. Our main result is volatility in China’s Shanghai gold futures market resulting from both macroeconomic fluctuations and investor behaviour. Chinese Consumer Price Index Volatility and US dollar volatility are the two main determinants of low-frequency gold volatility. We also find significant evidence of excess volatility, which can in part be explained in terms of loss-aversive investor behaviour.

  1. [Determination of volatile organic compounds in atmospheric environment].

    Science.gov (United States)

    Chen, H W; Li, G K; Li, H; Zhang, Z X; Wang, B G; Li, T; Luo, H K

    2001-11-01

    It is well known that volatile organic compounds (VOCs) are the main photochemical pollutants and ozone precursors of the photochemical smog. Investigation of photochemical pollution in the ambient air must focus on VOCs, but the concentration of VOCs in ambient air is in a very low level (10(-9)-10(-12), volume fraction), so there are difficulties in the determination of VOCs. In this work, based on the TO14A and TO15 methods recommended by the Environmental Protection Agency of United States, an improved method for the determination of fifty-six VOCs, mainly O3 precursors, in atmospheric environment was developed. Operating conditions of VOCs preconcentrator, gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS) were optimized. Air sample was first frozen by liquid nitrogen, and then H2O and CO2 were eliminated in the VOCs preconcentrator. The preconcentrated VOCs sample was injected to GC and detected by MS or hydrogen flame ionization detector (FID). The C2-C10 hydrocarbons were separated effectively in capillary columns under the high concentration of CO2. The detection limits were 0.1 microgram.m-3 and the relative standard deviations were in the range from 2.57% to 9.82%. This method has been used for the determination of VOCs in real samples. The results were satisfactory.

  2. Determining Energy Use Volatility for Commercial Mortgage Valuation

    Energy Technology Data Exchange (ETDEWEB)

    Mathew, Paul [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Pang, XiuFeng [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Wang, Liping [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

    2012-06-01

    Commercial mortgage contracts currently do not fully account for the risks inherent in the level and volatility of energy use in commercial buildings. As a result, energy efficiency is not explicitly included in the valuation process for commercial mortgage underwriting. In particular, there is limited if any consideration of the volatility of energy use and price, which is critical to evaluate the impact of extreme events and default risk. Explicit inclusion of energy use and volatility in commercial mortgage underwriting can send a strong “price signal” that financially rewards and values energy efficiency in commercial properties. This report presents the results of a technical analysis of and a proposed protocol to assess energy use volatility for the purposes of commercial mortgage valuation.

  3. Determination of volatiles produced during radiation processing in Laurus cinnamomum

    Energy Technology Data Exchange (ETDEWEB)

    Salum, D.C.; Araujo, M.M.; Fanaro, G.B. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Cidade Universitaria, Av. Professor Lineu Prestes 2242, Zip code: 05508-000 Butanta, Sao Paulo, SP (Brazil); Purgatto, E. [Faculdade de Ciencias Farmaceuticas, FCF/USP, Departamento de Alimentos e Nutricao Experimental. Av. Prof. Lineu Prestes, 580 Bloco 14. CEP: 05508-900 Sao Paulo, SP (Brazil)], E-mail: epurgatt@usp.br; Villavicencio, A.L.C.H. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Cidade Universitaria, Av. Professor Lineu Prestes 2242, Zip code: 05508-000 Butanta, Sao Paulo, SP (Brazil)], E-mail: villavic@ipen.br

    2009-07-15

    In order to protect food from pathogenic microorganisms as well as increase its shelf-life, while keeping sensorial properties (e.g., odor and taste), which are important properties required by spice buyers, it is necessary to analyze volatile formation from irradiation of medicinal and food herbs. Possible changes in the odor of these herbs are evaluated by characterizing different radiation doses and effects on sensorial properties, in order to allow better application of the irradiation technology. The aim of the present study was to analyze volatile formation on cinnamon (Laurus cinnamomum) samples after gamma irradiation. These samples were irradiated into plastic packages using a {sup 60}Co facility. Radiation doses applied were 0, 5, 10, 15, 20 and 25 kGy. For the analysis of the samples, solid-phase microextraction (SPME) was applied, while for the analysis of volatile compounds, CG/MS. Spice irradiation showed the highest decrease in volatile compounds. For L. cinnamomum, the irradiation decreased volatile compounds by nearly 56% and 89.5%, respectively, comparing to volatile from a sample which had not been previously irradiated.

  4. Determination of volatiles produced during radiation processing in Laurus cinnamomum

    Science.gov (United States)

    Salum, D. C.; Araújo, M. M.; Fanaro, G. B.; Purgatto, E.; Villavicencio, A. L. C. H.

    2009-07-01

    In order to protect food from pathogenic microorganisms as well as increase its shelf-life, while keeping sensorial properties (e.g., odor and taste), which are important properties required by spice buyers, it is necessary to analyze volatile formation from irradiation of medicinal and food herbs. Possible changes in the odor of these herbs are evaluated by characterizing different radiation doses and effects on sensorial properties, in order to allow better application of the irradiation technology. The aim of the present study was to analyze volatile formation on cinnamon ( Laurus cinnamomum) samples after gamma irradiation. These samples were irradiated into plastic packages using a 60Co facility. Radiation doses applied were 0, 5, 10, 15, 20 and 25 kGy. For the analysis of the samples, solid-phase microextraction (SPME) was applied, while for the analysis of volatile compounds, CG/MS. Spice irradiation showed the highest decrease in volatile compounds. For L. cinnamomum, the irradiation decreased volatile compounds by nearly 56% and 89.5%, respectively, comparing to volatile from a sample which had not been previously irradiated.

  5. Water-Air Volatilization Factors to Determine Volatile Organic Compound (VOC Reference Levels in Water

    Directory of Open Access Journals (Sweden)

    Vicenç Martí

    2014-06-01

    Full Text Available The goal of this work is the modeling and calculation of volatilization factors (VFs from water to air for volatile organic compounds (VOCs in order to perform human health risk-based reference levels (RLs for the safe use of water. The VF models have been developed starting from the overall mass-transfer coefficients (Koverall concept from air to water for two interaction geometries (flat surface and spherical droplets in indoor and outdoor scenarios. For a case study with five groups of risk scenarios and thirty VOCs, theoretical VFs have been calculated by using the developed models. Results showed that Koverall values for flat and spherical surface geometries were close to the mass transfer coefficient for water (KL when Henry’s law constant (KH was high. In the case of spherical drop geometry, the fraction of volatilization (fV was asymptotical when increasing KH with fV values also limited due to Koverall. VFs for flat surfaces were calculated from the emission flux of VOCs, and results showed values close to 1000KH for the most conservative indoor scenarios and almost constant values for outdoor scenarios. VFs for spherical geometry in indoor scenarios followed also constant VFs and were far from 1000KH. The highest calculated VF values corresponded to the E2A, E2B, E3A and E5A scenarios and were compared with experimental and real results in order to check the goodness of flat and sphere geometry models. Results showed an overestimation of calculated values for the E2A and E2B scenarios and an underestimation for the E3A and E5A scenarios. In both cases, most of the calculated VFs were from 0.1- to 10-times higher than experimental/real values.

  6. Determination of the solubility of low volatility liquid organic compounds in water using volatile-tracer assisted headspace gas chromatography.

    Science.gov (United States)

    Zhang, Shu-Xin; Chai, Xin-Sheng; Barnes, Donald G

    2016-02-26

    This study reports a new headspace gas chromatographic method (HS-GC) for the determination of water solubility of low volatility liquid organic compounds (LVLOs). The HS-GC analysis was performed on a set of aqueous solutions containing a range of concentrations of toluene-spiked (as a tracer) LVLOs, from under-saturation to over-saturation. A plot of the toluene tracer GC signal vs. the concentration of the LVLO results in two lines of different slopes that intersect at the concentration corresponding to the compound's solubility in water. The results showed that the HS-GC method has good precision (RSD solubility of LVLOs at elevated temperatures. This approach should be of special interest to those concerned about the impact of the presence of low-volatility organic liquids in waters of environmental and biological systems.

  7. Ethanol as Internal Standard for Quantitative Determination of Volatile Compounds in Spirit Drinks by Gas Chromatography

    CERN Document Server

    Charapitsa, Siarhei V; Kulevich, Nikita V; Makoed, Nicolai M; Mazanik, Arkadzi L; Sytova, Svetlana N

    2012-01-01

    The new methodical approach of using ethanol as internal standard in gas chromatographic analysis of volatile compounds in spirit drinks in daily practice of testing laboratories is proposed. This method provides determination of volatile compounds concentrations in spirit drinks directly expressed in milligrams per liter (mg/L) of absolute alcohol according to official methods without measuring of alcohol strength of analyzed sample. The experimental demonstration of this method for determination of volatile compounds in spirit drinks by gas chromatography is described. Its validation was carried out by comparison with experimental results obtained by internal standard method and external standard method.

  8. Extraction and GC determination of volatile aroma compounds from extracts of three plant species of the Apiaceae family

    Science.gov (United States)

    Stan, M.; Soran, M. L.; Varodi, C.; Lung, I.; Copolovici, L.; MǎruÅ£oiu, C.

    2013-11-01

    Parsley (Petroselinum crispum), dill (Anethum graveolens) and celery (Apium graveolens), three aromatic plants belonging to the Apiaceae (Umbelliferae) botanical family, were selected as sources of essential or volatile oils. Essential oils are composed of a large diversity of volatile aroma compounds. Plant-derived essential oils and extracts have long been used as natural agents in food preservation, pharmaceuticals and medicinal therapies. In the present study, the plant extracts from leaves of parsley, dill and celery, were obtained by maceration, ultrasound-assisted extraction and microwave-assisted extraction. All extractions were performed at 30°C, using different solvents (ethanol, diethyl ether, n-hexane) and solvent mixtures (1:1, v/v). The most effective solvent system for the extraction of volatile aroma compounds was diethyl ether - n-hexane (1:1, v/v). Extraction efficiency and determination of aroma volatiles were performed by GC-FID and GC-MS, respectively. The major volatile compounds present in plant extracts were myristicin, α-phellandrene, β-phellandrene, 1,3,8-p-menthatriene, apiol, dill ether and allyl phenoxyacetate.

  9. Determination of volatile marker compounds of common coffee roast defects.

    Science.gov (United States)

    Yang, Ni; Liu, Chujiao; Liu, Xingkun; Degn, Tina Kreuzfeldt; Munchow, Morten; Fisk, Ian

    2016-11-15

    Coffee beans from the same origin were roasted using six time-temperature profiles, in order to identify volatile aroma compounds associated with five common roast coffee defects (light, scorched, dark, baked and underdeveloped). Thirty-seven volatile aroma compounds were selected on the basis that they had previously been identified as potent odorants of coffee and were also identified in all coffee brew preparations; the relative abundance of these aroma compounds was then evaluated using gas chromatography mass spectrometry (GC-MS) with headspace solid phase micro extraction. Some of the 37 key aroma compounds were significantly changed in each coffee roast defect and changes in one marker compound was chosen for each defect type, that is, indole for light defect, 4-ethyl-2-methoxyphenol for scorched defect, phenol for dark defect, maltol for baked defect and 2,5-dimethylfuran for underdeveloped defect. The association of specific changes in aroma profiles for different roast defects has not been shown previously and could be incorporated into screening tools to enable the coffee industry quickly identify if roast defects occur during production.

  10. Simultaneous determination of volatile and non-volatile nitrosamines in processed meat products by liquid chromatography tandem mass spectrometry using atmospheric pressure chemical ionisation and electrospray ionisation

    DEFF Research Database (Denmark)

    Herrmann, Susan Strange; Duedahl-Olesen, Lene; Granby, Kit

    2014-01-01

    A sensitive, selective and generic method has been developed for the simultaneous determination of the contents (μgkg−1 range) of both volatile nitrosamines (VNA) and non-volatile nitrosamines (NVNA) in processed meat products. The extraction procedure only requires basic laboratory equipment and...

  11. Comparison of Methanol and Tetraglyme as Extraction Solvents for Determination of Volatile Organics in Soil

    Science.gov (United States)

    1987-11-01

    determining volatile organics in soil can be classified into thefollowing groups: 1. Static or dynamic headspace analysis 2. Solvent extraction-direct...methods based on the dynamic headspace method whereby the volatiles are stripped from a soil/water slurry using a conventional purge-and-trap instrument...651. Brazell, R.S. and MP. Maskarinec (1981) Dynamic headspace analysis of solid waste materials. Journal of High Resolution Chromatography and

  12. Gas chromatographic determination of volatile sulfur fluorides in air

    Energy Technology Data Exchange (ETDEWEB)

    Berezkin, V.G.; Drugov, Yu.S.

    1984-07-01

    An analytical method was developed for the determination of toxic products from thermooxidative destruction of sulfur hexafluoride (650-850/sup 0/C) found in the surrounding air of the work zone in production of high quality magnesium alloys. Sulfur hexafluoride (0.6-1.2%) and carbon dioxide (3-6%) are used as the protective atmosphere. The method involved preliminary concentration of lower sulfur fluorides in a cold trap filled with porapak Q followed with thermodesorption of concentrated impurities and their determination using a flame-photometric detector. The sensitivity of this method was 0.01 mg/m/sup 3/ and relative standard deviation 0.22-0.26. It was shown that when the temperature of the alloy increased from 720 to 800/sup 0/C, the content of HF over it increased from 6.7 to 15.5 mg/m/sup 3/. When zirconium alloy was introduced into this product, the concentration of HF above it reached the level of 52 mg/m/sup 3/, showing that it catalyzed the CF/sub 6/ thermodestruction process. 15 references, 2 figures.

  13. Volatile constituents of Melissa officinalis leaves determined by plant age.

    Science.gov (United States)

    Nurzyńska-Wierdak, Renata; Bogucka-Kocka, Anna; Szymczak, Grazyna

    2014-05-01

    The present study investigated changes in the content and chemical composition of the essential oil extracted by hydrodistillation from air-dried Melissa officinalis L. (lemon balm) leaves in the first and second year of plant growth. The lemon balm oil was analysed by GC-MS and GC-FID. The presence of 106 compounds, representing 100% of the oil constituents, was determined in the oil. The predominant components were geranial (45.2% and 45.1%) and neral (32.8% and 33.8%); their proportions in the examined samples of the oil obtained from one- and two-year-old plants were comparable. However, the age of lemon balm plants affected the concentration of other constituents and the proportions of the following compounds were subject to especially high fluctuations: citronellal (8.7% and 0.4%), geraniol (trace amounts and 0.6%), and geranyl acetate (0.5% and 3.0%), as well as, among others, isogeranial, E-caryophyllene, caryophyllene oxide, germacrene D, and carvacrol. The essential oil of two-year-old plants was characterized by a richer chemical composition than the oil from younger plants.

  14. Conventional and Islamic indices in Indonesia: A Comparison on Performance, Volatility, and the Determinants

    Directory of Open Access Journals (Sweden)

    Nika Pranata

    2015-10-01

    Full Text Available The purpose of this study is to evaluate performance and volatility of Islamic andconventional stock indices along with their determinant factor variables in Indonesia. The study adopts: (1 Capital Asset Pricing Model (CAPM to compare the performance of the Jakarta Islamic Index (JII to represent Islamic indexandLQ45 to represent the conventional, (2 beta calculation to measure volatility, and (3 Autoregressive Distributed Lag (ARDL to capture the determinants and the reason behind the outperformance. The data coverage is from January 2006 to November 2015. The study finds that: (1 There is no significant differenceon performance between JII and LQ45, (2 JII is less volatile than LQ45, except in 2010, and (3JII performance is less affected by external factorsexcept for crude oil price. Moreover, the result implies challenge for the authorities to educate society, particularly whom concern to shari’ah principles, with information that Islamic index performance is not much difference from conventional index and less volatile.

  15. An inverse problem of determining the implied volatility in option pricing

    Science.gov (United States)

    Deng, Zui-Cha; Yu, Jian-Ning; Yang, Liu

    2008-04-01

    In the Black-Scholes world there is the important quantity of volatility which cannot be observed directly but has a major impact on the option value. In practice, traders usually work with what is known as implied volatility which is implied by option prices observed in the market. In this paper, we use an optimal control framework to discuss an inverse problem of determining the implied volatility when the average option premium, namely the average value of option premium corresponding with a fixed strike price and all possible maturities from the current time to a chosen future time, is known. The issue is converted into a terminal control problem by Green function method. The existence and uniqueness of the minimum of the control functional are addressed by the optimal control method, and the necessary condition which must be satisfied by the minimum is also given. The results obtained in the paper may be useful for those who engage in risk management or volatility trading.

  16. Determination of volatile organic compounds in water using headspace knotted hollow fiber microextraction.

    Science.gov (United States)

    Chen, Pai-Shan; Tseng, Yu-Hsiang; Chuang, Yuh-Lin; Chen, Jung-Hsuan

    2015-05-22

    An efficient and effective headspace microextraction technique named static headspace knotted hollow fiber microextraction (HS-K-HFME) has been developed for the determination of volatile organic compounds (VOCs) in water samples. The knot-shaped hollow fiber is filled with 25μL of the extraction solvent. The excess solvent forms a large droplet (13μL) and is held in the center of the knot. Even after 20min of extraction time at high temperature (95°C) without cooling, there was still enough volume of extraction solvent for gas chromatography-mass spectrometry (GC-MS) analysis, which extends the choice of solvents for headspace LPME. Moreover, the knot-shaped fiber has a larger extraction contact interface, which increases the rate of mass transfer between the headspace and extraction solvent film attached to the fiber, thus improving the extraction efficiency. The effects of extraction solvent, temperature, stirring rate, salt concentration and extraction time on extraction performance were optimized. The calibration curves exhibited coefficients of determination (R(2)) ranging from 0.9957 to 0.9999 and the limit of detection (LOD) ranged from 0.2 to 10μgL(-1). Relative standard deviations (RSDs) ranged from 4.5% to 11.6% for intraday measurements (n=5). Interday (n=15) values were between 2.2% and 12.9%. The relative recoveries (RRs) ranged from 90.3% to 106.0% for river water and 95.9% to 103.6% for wastewater.

  17. Volatile Metabolites

    Directory of Open Access Journals (Sweden)

    Daryl D. Rowan

    2011-11-01

    Full Text Available Volatile organic compounds (volatiles comprise a chemically diverse class of low molecular weight organic compounds having an appreciable vapor pressure under ambient conditions. Volatiles produced by plants attract pollinators and seed dispersers, and provide defense against pests and pathogens. For insects, volatiles may act as pheromones directing social behavior or as cues for finding hosts or prey. For humans, volatiles are important as flavorants and as possible disease biomarkers. The marine environment is also a major source of halogenated and sulfur-containing volatiles which participate in the global cycling of these elements. While volatile analysis commonly measures a rather restricted set of analytes, the diverse and extreme physical properties of volatiles provide unique analytical challenges. Volatiles constitute only a small proportion of the total number of metabolites produced by living organisms, however, because of their roles as signaling molecules (semiochemicals both within and between organisms, accurately measuring and determining the roles of these compounds is crucial to an integrated understanding of living systems. This review summarizes recent developments in volatile research from a metabolomics perspective with a focus on the role of recent technical innovation in developing new areas of volatile research and expanding the range of ecological interactions which may be mediated by volatile organic metabolites.

  18. Tequila volatile characterization and ethyl ester determination by solid phase microextraction gas chromatography/mass spectrometry analysis.

    Science.gov (United States)

    Vallejo-Cordoba, Belinda; González-Córdova, Aarón Fernando; del Carmen Estrada-Montoya, María

    2004-09-08

    Solid phase microextraction (SPME) and gas chromatography were used for tequila volatile characterization and ethyl ester quantitation. Several factors determined the differences in tequila volatile profiles obtained by the SPME technique, namely, sampling mode, fiber coating, and fiber exposure time. Each of these factors determined the most suitable conditions for the analysis of volatile profiles in tequila. Volatile extraction consisted of placing 40 mL of tequila in a sealed vial kept at 40 degrees C. A poly(dimethylsiloxane) fiber was immersed in the liquid for 60 min and desorbed for 5 min into the gas chromatograph. The identified volatiles by mass spectrometry were mainly alcohols, esters, and ketones. The calibration curves for ethyl hexanoate, octanoate, and decanoate followed linear relationships with highly significant (p tequila samples. Quantitative differences in ethyl esters were found for the four most commonly known tequila types: silver, gold, aged, and extra-aged.

  19. Highly sensitive electromembrane extraction for the determination of volatile organic compound metabolites in dried urine spot.

    Science.gov (United States)

    Suh, Joon Hyuk; Eom, Han Young; Kim, Unyong; Kim, Junghyun; Cho, Hyun-Deok; Kang, Wonjae; Kim, Da Som; Han, Sang Beom

    2015-10-16

    Electromembrane extraction coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS) was developed for determination of ten volatile organic compound metabolites in dried urine spot samples. The dried urine spot approach is a convenient and economical sampling method, wherein urine is spotted onto a filter paper and dried. This method requires only a small amount of sample, but the analysis sometimes suffers from low sensitivity, which can lead to analytical problems in the detection of minor components in samples. The newly developed dried urine spot analysis using electromembrane extraction exhibited improved sensitivity and extraction, and enrichment of the sample was rapidly achieved in one step by applying an electric field. Aliquots of urine were spotted onto Bond Elut DMS cards and dried at room temperature. After drying, the punched out dried urine spot was eluted with water. Volatile organic compound metabolites were extracted from the sample through a supported liquid membrane into an alkaline acceptor solution inside the lumen of a hollow fiber with the help of an electric potential. The optimum extraction conditions were determined by using design of experiments (fractional factorial design and response surface methodology). Satisfactory sensitivity was achieved and the limits of quantification (LOQ) obtained were lower than the regulatory threshold limits. The method was validated by assessing the linearity, precision, accuracy, recovery, reproducibility, stability, and matrix effects. The results were acceptable, and the developed method was successfully applied to biological exposure monitoring of volatile organic compound metabolites in fifty human urine samples.

  20. Comparison of SPME Methods for Determining Volatile Compounds in Milk, Cheese, and Whey Powder

    Directory of Open Access Journals (Sweden)

    Michael H. Tunick

    2013-11-01

    Full Text Available Solid phase microextraction and gas chromatography-mass spectrometry (SPME-GC-MS are commonly used for qualitative and quantitative analysis of volatile compounds in various dairy products, but conditions have to be adjusted to maximize release while not generating new compounds that are absent in the original sample. Queso Fresco, a fresh non-melting cheese, may be heated at 60 °C for 30 min; in contrast, compounds are produced in milk when exposed to light and elevated temperatures, so milk samples are heated as little as possible. Products such as dehydrated whey protein are more stable and can be exposed to longer periods (60 min of warming at lower temperature (40 °C without decomposition, allowing for capture and analysis of many minor components. The techniques for determining the volatiles in dairy products by SPME and GC-MS have to be optimized to produce reliable results with minimal modifications and analysis times.

  1. Estimation of the Accuracy of Method for Quantitative Determination of Volatile Compounds in Alcohol Products

    CERN Document Server

    Charepitsa, S V; Zadreyko, Y V; Sytova, S N

    2016-01-01

    Results of the estimation of the precision for determination volatile compounds in alcohol-containing products by gas chromatography: acetaldehyde, methyl acetate, ethyl acetate, methanol, isopropyl alcohol, propyl alcohol, isobutyl alcohol, butyl alcohol, isoamyl alcohol are presented. To determine the accuracy, measurements were planned in accordance with ISO 5725 and held at the gas chromatograph Crystal-5000. Standard deviation of repeatability, intermediate precision and their limits are derived from obtained experimental data. The uncertainty of the measurements was calculated on the base of an "empirical" method. The obtained values of accuracy indicate that the developed method allows measurement uncertainty extended from 2 to 20% depending on the analyzed compound and measured concentration.

  2. Analysis of volatile organic compounds in compost samples: A potential tool to determine appropriate composting time.

    Science.gov (United States)

    Zhu, Fengxiang; Pan, Zaifa; Hong, Chunlai; Wang, Weiping; Chen, Xiaoyang; Xue, Zhiyong; Yao, Yanlai

    2016-12-01

    Changes in volatile organic compound contents in compost samples during pig manure composting were studied using a headspace, solid-phase micro-extraction method (HS-SPME) followed by gas chromatography with mass spectrometric detection (GC/MS). Parameters affecting the SPME procedure were optimized as follows: the coating was carbon molecular sieve/polydimethylsiloxane (CAR/PDMS) fiber, the temperature was 60°C and the time was 30min. Under these conditions, 87 compounds were identified from 17 composting samples. Most of the volatile components could only be detected before day 22. However, benzenes, alkanes and alkenes increased and eventually stabilized after day 22. Phenol and acid substances, which are important factors for compost quality, were almost undetectable on day 39 in natural compost (NC) samples and on day 13 in maggot-treated compost (MC) samples. Our results indicate that the approach can be effectively used to determine the composting times by analysis of volatile substances in compost samples. An appropriate composting time not only ensures the quality of compost and reduces the loss of composting material but also reduces the generation of hazardous substances. The appropriate composting times for MC and NC were approximately 22days and 40days, respectively, during the summer in Zhejiang.

  3. Comprehensive verification of new method "Ethanol as Internal Standard" for determination of volatile compounds in alcohol products by gas chromatography

    CERN Document Server

    Charapitsa, Siarhei V; Markovsky, Mikhail G; Yakuba, Yurii F; Kotov, Yurii N

    2014-01-01

    Recently proposed new method "Ethanol as Internal Standard" for determination of volatile compounds in alcohol products by gas chromatography is investigated from different sides. Results of experimental study from three different laboratories from Belarus and Russian Federation are presented.

  4. Volatile organic compound (VOC) determination in working atmospheres; Determinacion de compuestos organicos volatiles (VOC) en ambiente laboral

    Energy Technology Data Exchange (ETDEWEB)

    Blass A, Georgina; Panama T, Luz A; Corrales C, Deyanira [Instituto de Investigaciones Electricas, Cuernavaca, Morelos (Mexico)

    2003-07-01

    The present work describes, in a synthesized way, the implementation and application of procedures based on the normativity related to the subject of the volatile organic compounds (Volatile Organic Compounds VOC), that allow to sample, quantify and evaluate the present contamination in the working atmosphere of a refinery due to the fugitive emissions of VOC and other substances. In accordance with the corresponding normativity, more than 189 organic compounds denominated dangerous air polluting agents (Hazardous Air Pollutants, HAP) can be found in a working atmosphere, but they are the 11 main HAP that can be found in a refinery. In the present article the work made for the sampling and quantification of 5 of the 11 dangerous polluting agents of the air: benzene, toluene, xylene, iso-octane and naphthalene. [Spanish] El presente trabajo describe, de manera sintetizada, la implementacion y aplicacion de procedimientos basados en la normatividad relacionada al tema de los compuestos organicos volatiles (Volatil Organic Compounds, VOC), que permiten muestrear, cuantificar y evaluar la contaminacion presente en el ambiente laboral de una refineria debido a las emisiones fugitivas de VOC y otras sustancias. De acuerdo con la normatividad correspondiente, mas de 189 compuestos organicos denominados contaminantes peligrosos del aire (Hazardous Air Pollutants, HAP), pueden ser encontrados en un ambiente laboral, pero son 11 los principales HAP que pueden ser hallados en una refineria. En el presente articulo se informa el trabajo realizado para el muestreo y cuantificacion de 5 de los 11 contaminantes peligrosos del aire: benceno, tolueno, xileno, iso-octano y naftaleno.

  5. Correct quantitative determination of ethanol and volatile compounds in alcohol products

    CERN Document Server

    Charapitsa, Siarhei; Sytova, Svetlana; Yakuba, Yurii

    2014-01-01

    Determination of the volume content of ethanol in the alcohol products in practice is usually determined by pycnometry, electronic densimetry, or densimetry using a hydrostatic balance in accordance with Commission Regulation No 2870/2000. However, these methods determine directly only density of the tested liquid sample and does not take into account the effects of other volatile components such as aldehydes, esters and higher alcohols. So they are appropriate only for binary water-ethanol solutions in accordance with international table adopted by the International Legal Metrology Organization in its Recommendation No 22. Availability notable concentrations of the higher alcohols and ethers in different alcohol-based products, e. g. in whisky, cognac, brandy, wine as well as in waste alcohol and alcohol beverage production, leads to the significant contribution of these compounds in the value of the density of tested alcohol-containing sample. As a result, determination of the volume of ethanol content for ...

  6. Determination of Trace and Volatile Element Abundance Systematics of Lunar Pyroclastic Glasses 74220 and 15426 Using LA-ICP-MS

    Science.gov (United States)

    McIntosh, E. Carrie; Porrachia, Magali; McCubbin, Francis M.; Day, James M. D.

    2017-01-01

    Since their recognition as pyroclastic glasses generated by volcanic fire fountaining on the Moon, 74220 and 15426 have garnered significant scientific interest. Early studies recognized that the glasses were particularly enriched in volatile elements on their surfaces. More recently, detailed analyses of the interiors of the glasses, as well as of melt inclusions within olivine grains associated with the 74220 glass beads, have determined high H2O, F, Cl and S contents. Such elevated volatile contents seem at odds with evidence from moderately volatile elements (MVE), such as Zn and K, for a volatile- depleted Moon. In this study, we present initial results from an analytical campaign to study trace element abundances within the pyroclastic glass beads. We report trace element data determined by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) for 15426 and 74220.

  7. Determination of volatile organic compounds responsible for flavour in cooked river buffalo meat

    Directory of Open Access Journals (Sweden)

    A. Di Luccia

    2010-02-01

    Full Text Available Flavour is an important consumer attractive that directly influences the success of food products on the market. The determination of odorous molecules and their identification allows to useful knowledge for producers to valorise their own products. Buffalo meat has a different chemical composition from pork and beef and requires some cautions in cooking and processing. This work aims at the identification of volatile molecules responsible for flavours in river buffalo meat. The determination was carried out by solid phase micro-extraction (SPME technique and analysed by gas chromatography coupled to mass spectrometry (GC-MS. The most relevant results were the higher odorous impact of buffalo meat and the higher content of sulphide compounds responsible for wild aroma respect to pork and beef. These results were obtained comparing the total area of peaks detected in every chromatogram. We have also found significant differences concerning the contents of pentadecane, 1-hexanol-2 ethyl, butanoic acid, furano-2-penthyl. The origin of volatile organic compounds and their influence on the river buffalo aromas were discussed.

  8. Determination of acrolein, ethanol, volatile acidity, and copper in different samples of sugarcane spirits

    Directory of Open Access Journals (Sweden)

    José Masson

    2012-09-01

    Full Text Available Seventy-one samples of sugarcane spirits from small and average size stills produced in the northern and southern Minas Gerais (Brazil were analyzed for acrolein using HPLC (High Performance Liquid Chromatography. Ethanol and copper concentrations and volatile acidity were also determined according to methods established by the Ministry of Agriculture, Livestock and Supply (MAPA. A total of 9.85% of the samples tested showed levels of acrolein above the legal limits, while the copper concentrations of 21.00% of the samples and the volatile acidity of 8.85% of the samples were higher than the limits established by the Brazilian legislation. The concentration of acrolein varied from 0 to 21.97 mg.100 mL-1 of ethanol. However, no significant difference at 5% of significance was observed between the samples produced in the northern and southern Minas Gerais. The method used for determination of acrolein in sugarcane spirits involved the formation of a derivative with 2,4-dinitrophenylhydrazine (2,4-DNPH and subsequent analysis by HPLC.

  9. Determination of Volatiles by Odor Activity Value and Phenolics of cv. Ayvalik Early-Harvest Olive Oil

    OpenAIRE

    Gamze Guclu; Onur Sevindik; Hasim Kelebek; Serkan Selli

    2016-01-01

    Ayvalik is an important olive cultivar producing high quality oils in Turkey. In the present study, volatile and phenolic compositions of early-harvest extra virgin olive oil (cv. Ayvalik) were determined. The solvent-assisted flavor evaporation (SAFE) technique was used for the extraction of volatile components. The aromatic extract obtained by SAFE was representative of the olive oil odor. A total of 32 aroma compounds, including alcohols, aldehydes, terpenes, esters, and an acid, were iden...

  10. Determination of inorganic pollutants in soil after volatilization using microwave-induced combustion

    Energy Technology Data Exchange (ETDEWEB)

    Picoloto, Rochele S. [Departamento de Química, Universidade Federal de Santa Maria, 97105-900, Santa Maria, RS, Brazil and Instituto Nacional de Ciência e Tecnologia de Bioanalítica, Campinas, SP (Brazil); Wiltsche, Helmar; Knapp, Günter [Institute of Analytical Chemistry and Food Chemistry, Graz University of Technology, Graz (Austria); Mello, Paola A. [Departamento de Química, Universidade Federal de Santa Maria, 97105-900, Santa Maria, RS, Brazil and Instituto Nacional de Ciência e Tecnologia de Bioanalítica, Campinas, SP (Brazil); Barin, Juliano S. [Departamento de Tecnologia e Ciência dos Alimentos, Universidade Federal de Santa Maria, 97105-900, Santa Maria, RS (Brazil); Flores, Erico M.M., E-mail: ericommf@gmail.com [Departamento de Química, Universidade Federal de Santa Maria, 97105-900, Santa Maria, RS, Brazil and Instituto Nacional de Ciência e Tecnologia de Bioanalítica, Campinas, SP (Brazil)

    2013-08-01

    Microwave-induced combustion (MIC) was applied for analyte volatilization from soil and subsequent determination of As, Cd and Pb by inductively coupled plasma mass spectrometry (ICP-MS) and inductively coupled plasma optical emission spectrometry (ICP-OES), and Hg by cold vapor generation inductively coupled plasma mass spectrometry (CVG-ICP-MS). Soil samples (up to 300 mg) were mixed with microcrystalline cellulose, pressed as pellets and combusted in closed quartz vessels pressurized with 20 bar O{sub 2}. Analytes were volatilized from soil during combustion and quantitatively absorbed in a suitable solution: nitric acid (1, 2, 4 or 6 mol L{sup −1}) or a solution of nitric (2 mol L{sup −1}) and hydrochloric (1, 2 or 4 mol L{sup −1}) acids. Accuracy was evaluated using certified reference materials of soil (NIST 2709, San Joaquin Soil) and sediment (SUD-1, Sudbury sediment for trace elements). Agreement with certified values was better than 95% (t-test, 95% confidence level) for all analytes when 6 mL of a solution of 2 mol L{sup −1} HNO{sub 3} and 2 mol L{sup −1} HCl was used with a reflux step of 5 min. The limit of detection was 0.010, 0.002, 0.009 and 0.012 μg g{sup −1} for As, Cd, Hg and Pb, respectively using ICP-MS determination. A clear advantage of the proposed method over classical approaches is that only diluted solution is used. Moreover, a complete separation of the analytes from matrix is achieved minimizing potential interferences in ICP-MS or ICP-OES determination. Up to eight samples can be digested in a single run of only 25 min, resulting in a solution suitable for the determination of all analytes by both techniques. - Highlights: ► Microwave-induced combustion method was applied for soil samples. ► Analytes were volatilized during MIC allowing a suitable separation from matrix. ► Matrix interferences during the determination step are minimized. ► As, Cd, Hg and Pb were determined by ICP-MS. ► Diluted acid solutions were

  11. The Use of Amberlite Adsorbents for Green Chromatography Determination of Volatile Organic Compounds in Air

    Directory of Open Access Journals (Sweden)

    Luis Juan-Peiró

    2012-01-01

    Full Text Available Passive samplers have been widely used for volatile organic compounds determination. Following the green chemistry tendency of the direct determination of adsorbed compounds in membrane-based devices through using head space direct chromatography analysis, this work has evaluated the use of Amberlite XAD-2, XAD-4, and XAD-16 adsorbents as a filling material for passive samplers. Direct analysis of the membranes by HS-GC-MS involves a solvent-free method avoiding any sample treatment. For exposed membranes, recoveries ranged from 10% to 203%, depending on the compound and adsorbent used. The limit of the detection values ranged from 1 to 140 ng per sampler. Acceptable precision and sensitivity levels were obtained for the XAD resins assayed.

  12. Large drought-induced variations in oak leaf volatile organic compound emissions during PINOT NOIR 2012.

    Science.gov (United States)

    Geron, Chris; Daly, Ryan; Harley, Peter; Rasmussen, Rei; Seco, Roger; Guenther, Alex; Karl, Thomas; Gu, Lianhong

    2016-03-01

    Leaf-level isoprene and monoterpene emissions were collected and analyzed from five of the most abundant oak (Quercus) species in Central Missouri's Ozarks Region in 2012 during PINOT NOIR (Particle Investigations at a Northern Ozarks Tower - NOx, Oxidants, Isoprene Research). June measurements, prior to the onset of severe drought, showed isoprene emission rates and leaf temperature responses similar to those previously reported in the literature and used in Biogenic Volatile Organic Compound (BVOC) emission models. During the peak of the drought in August, isoprene emission rates were substantially reduced, and response to temperature was dramatically altered, especially for the species in the red oak subgenus (Erythrobalanus). Quercus stellata (in the white oak subgenus Leucobalanus), on the other hand, increased its isoprene emission rate during August, and showed no decline at high temperatures during June or August, consistent with its high tolerance to drought and adaptation to xeric sites at the prairie-deciduous forest interface. Mid-late October measurements were conducted after soil moisture recharge, but were affected by senescence and cooler temperatures. Isoprene emission rates were considerably lower from all species compared to June and August data. The large differences between the oaks in response to drought emphasizes the need to consider BVOC emissions at the species level instead of just the whole canopy. Monoterpene emissions from Quercus rubra in limited data were highest among the oaks studied, while monoterpene emissions from the other oak species were 80-95% lower and less than assumed in current BVOC emission models. Major monoterpenes from Q. rubra (and in ambient air) were p-cymene, α-pinene, β-pinene, d-limonene, γ-terpinene, β-ocimene (predominantly1,3,7-trans-β-ocimene, but also 1,3,6-trans-β-ocimene), tricyclene, α-terpinene, sabinene, terpinolene, and myrcene. Results are discussed in the context of canopy flux studies

  13. Determination of volatile compounds and quality parameters of traditional Istrian dry-cured ham.

    Science.gov (United States)

    Marušić, Nives; Vidaček, Sanja; Janči, Tibor; Petrak, Tomislav; Medić, Helga

    2014-04-01

    The aim of this work was to determine the characteristics of Istrian dry-cured ham by instrumental methods and sensory analysis. The aroma-active compounds of Istrian dry-cured ham from 2010 and 2012 were investigated by using headspace-solid phase microextraction (SPME) and gas chromatography-mass spectrometry (GC-MS). Samples of biceps femoris were also evaluated by measuring physical and chemical characteristics. 92 volatile aroma compounds of Istrian dry-cured ham were found. Volatile compounds belonged to several chemical groups: aldehydes (51.4; 51.3%), terpenes (16.5; 16.4%), alcohols (15.5; 13.2%), ketones (8.6; 7.4%), alkanes (3.8; 5.7%), esters (1.3; 1.6%), aromatic hydrocarbons (0.8; 3.9%) and acids (0.6; 0.9%). Principal component analysis (PCA) showed that fat content, tenderness and melting texture were positively correlated. Terpenes were strongly correlated with flavour of added spices. Sweet taste and the presence of esters were positively correlated as well as negative odour, raw meat flavour and water content.

  14. The determination of botanical origin of honeys based on enantiomer distribution of chiral volatile organic compounds.

    Science.gov (United States)

    Špánik, Ivan; Pažitná, Alexandra; Šiška, Peter; Szolcsányi, Peter

    2014-09-01

    The enantiomer ratios of chiral volatile organic compounds in rapeseed, chestnut, orange, acacia, sunflower and linden honeys were determined by multi-dimensional gas chromatography using solid phase microextraction (SPME) as a sample pre-treatment procedure. Linalool oxides, linalool and hotrienol were present at the highest concentration levels, while significantly lower amounts of α-terpineol, 4-terpineol and all isomers of lilac aldehydes were found in all studied samples. On the other hand, enantiomer distribution of some chiral organic compounds in honey depends on their botanical origin. The significant differences in enantiomer ratio of linalool were observed for rapeseed honey that allows us to distinguish this type of honey from the other ones. The enantiomer ratios of lilac aldehydes were useful for distinguishing of orange and acacia honey from other studied monofloral honeys. Similarly, different enantiomer ratio of 4-terpineol was found for sunflower honeys.

  15. Determination of fine particulate semi-volatile organic material at three eastern U.S. sampling sites.

    Science.gov (United States)

    Warner, K S; Eatough, D J; Stockburger, L

    2001-09-01

    Correct assessment of fine particulate carbonaceous material as a function of particle size is, in part, dependent on the determination of semi-volatile compounds, which can be lost from particles during sampling. This study gives results obtained for the collection of fine particulate carbonaceous material at three eastern U.S. sampling sites [Philadelphia, PA; Shenandoah National Park, VA; and Research Triangle Park (RTP), NC] using diffusion denuder technology. The diffusion denuder samplers allow for the determination of fine particulate organic material with no artifacts, due to the loss of semi-volatile organic particulate compounds, or collection of gas-phase organic compounds by the quartz filter during sampling. The results show that an average of 41, 43, and 59% of fine particulate organic material was lost as volatilized semi-volatile organic material during collection of particles on a filter at Philadelphia, RTP, and Shenandoah, respectively. The particle size distribution of carbonaceous material retained by a filter and lost from a filter during sampling was obtained for the samples collected at Philadelphia and Shenandoah. The carbonaceous material retained by the particles during sampling was found predominantly in particles smaller than 0.4 microm in aerodynamic diameter. In contrast, the semi-volatile organic material lost from the particles during sampling had a mass median diameter of approximately 0.5 microm.

  16. Determination of volatile glucosinolate degradation products in seed coat, stem and in vitro cultures of Moringa peregrina (Forssk.) Fiori.

    Science.gov (United States)

    Dehshahri, S; Afsharypuor, S; Asghari, G; Mohagheghzadeh, A

    2012-01-01

    Moringaceae, a monogeneric family in Capparales (glucosinolate-containing species), includes 14 species. One of them is Moringa peregrina (Forssk.) Fiori., a small tree, which grows in south east of Iran. Volatile constituents of seed coat and stem of M. peregrina were determined by GC and GC/MS. Moreover, extracts of seed and different cultured cells were analyzed by TLC and GC. Three volatile isothiocyanates including isopropyl isothiocyanate (4.2%), sec-butyl isothiocyanate (< 0.1%) and isobutyl isothiocyanate (92.9%) were found in the volatile oil of the stem , while only two volatile isothiocyanates namely isopropyl isothiocyanate (7.0%) and isobutyl isothiocyanate (51.5%) were determined in the seed coat of the tree. For the first time, the callus and suspension cultures of M. peregrina were initiated and established successfully on Murashige and Skoog medium, containing plant growth hormones. Different precursors and elicitors were fed to the cultures to induce glucosinolates production. This is the first report of in vitro culture production of M. peregrina. There was no production of volatile isothiocyanates in M. peregrina callus and suspension cultures with different treatments.

  17. Determination of volatile and non-volatile products of milk fermentation processes using capillary zone electrophoresis and solid phase microextraction coupled to gas chromatography.

    Science.gov (United States)

    Ligor, Magdalena; Jarmalaviciene, Reda; Szumski, Michal; Maruska, Audrius; Buszewski, Boguslaw

    2008-08-01

    The aim of the investigations was to develop analytical methods for the determination of selected volatile and non-volatile organic compounds numbering among the final products of milk fermentation. The analyzed compounds were as follows: biacetyl and carboxylic acids (formic, acetic, citric, and lactic). The model yogurt was prepared under controlled conditions in our laboratory by addition of the selected bacteria (Lactobacillus bulgaricus and Streptococcus thermophilus) to the milk sample. The temperature, time, and stirring were controlled during the fermentation process. Factors considered in SPMPE-GC-FID method development included fiber exposure time, salt addition, temperature of extraction, and temperature of desorption. Various SPME fibers, for example with PDMS, CAR/PDMS, PA, and PDMS/DVB coatings, were tested to obtain the highest recovery of the investigated compounds extracted from yogurt samples. Based on these preliminary experiments, qualitative and quantitative analyses for the determination of biacetyl were performed by SPME-GC-FID. Moreover, a capillary zone electrophoresis method was developed for the determination of carboxylic acids in the yogurt samples. The buffer composition as well as deproteinization by acetonitrile were found to have a crucial effect on the analysis.

  18. Large increases in Arctic biogenic volatile emissions are a direct effect of warming

    Science.gov (United States)

    Kramshøj, Magnus; Vedel-Petersen, Ida; Schollert, Michelle; Rinnan, Åsmund; Nymand, Josephine; Ro-Poulsen, Helge; Rinnan, Riikka

    2016-05-01

    Biogenic volatile organic compounds are reactive gases that can contribute to atmospheric aerosol formation. Their emission from vegetation is dependent on temperature and light availability. Increasing temperature, changing cloud cover and shifting composition of vegetation communities can be expected to affect emissions in the Arctic, where the ongoing climate changes are particularly severe. Here we present biogenic volatile organic compound emission data from Arctic tundra exposed to six years of experimental warming or reduced sunlight treatment in a randomized block design. By separately assessing the emission response of the whole ecosystem, plant shoots and soil in four measurements covering the growing season, we have identified that warming increased the emissions directly rather than via a change in the plant biomass and species composition. Warming caused a 260% increase in total emission rate for the ecosystem and a 90% increase in emission rates for plants, while having no effect on soil emissions. Compared to the control, reduced sunlight decreased emissions by 69% for the ecosystem, 61-65% for plants and 78% for soil. The detected strong emission response is considerably higher than observed at more southern latitudes, emphasizing the high temperature sensitivity of ecosystem processes in the changing Arctic.

  19. Chasing volatility

    DEFF Research Database (Denmark)

    Caporin, Massimiliano; Rossi, Eduardo; Santucci de Magistris, Paolo

    The realized volatility of financial returns is characterized by persistence and occurrence of unpreditable large increments. To capture those features, we introduce the Multiplicative Error Model with jumps (MEM-J). When a jump component is included in the multiplicative specification, the condi...... models, the introduction of the jump component provides a sensible improvement in the fit, as well as for in-sample and out-of-sample volatility tail forecasts....

  20. Comparison of methods for determining volatile compounds in cheese, milk, and whey powder

    Science.gov (United States)

    Solid phase microextraction (SPME) and gas chromatography-mass spectrometry (GC-MS) are commonly used for qualitative and quantitative analysis of volatile compounds in various dairy products, but selecting the proper procedures presents challenges. Heat is applied to drive volatiles from the samp...

  1. Determination of volatile halogenated organic compounds in the tropical terrestrial ecosystem

    Energy Technology Data Exchange (ETDEWEB)

    Quintana, A.; Lopez-Garriga, J. [Univ. of Puerto Rico, Mayaguez (Puerto Rico)

    1995-12-01

    Volatile Halogenated Organic Compounds are discharged into our biosphere by plants, marine organisms, fungi and by other natural processes. Due to the high rate of evaporation of the tropical terrestrial ecosystem, the production of VHOC by fungi, higher plants and other organisms may be one of the most important sources of the total amount of VHOC released to the atmosphere from biogenic origin. The main goal of this research was to determine the VHOC`s released to the surroundings from biogenic origin in the tropical terrestrial ecosystem. Using vacuum distillation with cryogenic trapping and a thermal desorption unit coupled to a GC-ECD, we found that samples of air, water and soil contains 36.418 ng/L, 0.222 ng/mL and 9.156 ng/g (wet) of chloroform. Microorganisms such as the Actinomycetes and Halobacterium salinarium were also analyzed for VHOC`S contents. Carbontetrachloride, 1,1-dichloroethene, dichlorodifluoromethane, trichlorofluoromethane and other VHOC`S of environmental importance were determined. This is the first time that the presence of VHOC`S is reported in pure cultured bacteria.

  2. Determinants of exposure to volatile organic compounds in four Oklahoma cities.

    Science.gov (United States)

    Phillips, Margaret L; Esmen, Nurtan A; Hall, Thomas A; Lynch, Robert

    2005-01-01

    To begin to develop generalized models for estimating personal exposure to ambient air pollutants within diverse populations, the design of the Oklahoma Urban Air Toxics Study incorporated eight dichotomous macroenvironmental and household factors that were hypothesized to be potential determinants of exposure. Personal, indoor, and outdoor samples of volatile organic compounds (VOCs) were collected over 24-h monitoring periods in 42 households, together with activity diaries and data on the participants' residences. The distributions of the VOC concentrations were moderately to highly left-censored, and were mostly bimodal. The ATSDR minimal risk level (MRL) was exceeded in a small number of the samples. Personal and indoor concentrations tended to be higher than outdoor concentrations, indicating that indoor exposures were dominated by indoor sources. However, indoor concentrations were not correlated with the permeability of the residence, suggesting that the observed indoor concentrations reflected mostly localized, short-term emissions. The influence of the eight dichotomous factors and of the presence of an attached garage was evaluated using the Wilcoxon rank-sum test and by comparison of "excursion fractions", that is, the fractions of each distributions exceeding 10% of the MRL. Dry weather and absence of children in the household were found to be associated with higher exposures in personal or indoor exposures. Given the small sample size, it is possible that these factors were confounded with unidentified household characteristics or activities that were the true determinants of exposure.

  3. Determination of volatile compounds in four commercial samples of Japanese green algae using solid phase microextraction gas chromatography mass spectrometry.

    Science.gov (United States)

    Yamamoto, Masayoshi; Baldermann, Susanne; Yoshikawa, Keisuke; Fujita, Akira; Mase, Nobuyuki; Watanabe, Naoharu

    2014-01-01

    Green algae are of great economic importance. Seaweed is consumed fresh or as seasoning in Japan. The commercial value is determined by quality, color, and flavor and is also strongly influenced by the production area. Our research, based on solid phase microextraction gas chromatography mass spectrometry (SPME-GC-MS), has revealed that volatile compounds differ intensely in the four varieties of commercial green algae. Accordingly, 41 major volatile compounds were identified. Heptadecene was the most abundant compound from Okayama (Ulva prolifera), Tokushima (Ulva prolifera), and Ehime prefecture (Ulva linza). Apocarotenoids, such as ionones, and their derivatives were prominent volatiles in algae from Okayama (Ulva prolifera) and Tokushima prefecture (Ulva prolifera). Volatile, short chained apocarotenoids are among the most potent flavor components and contribute to the flavor of fresh, processed algae, and algae-based products. Benzaldehyde was predominant in seaweed from Shizuoka prefecture (Monostroma nitidum). Multivariant statistical analysis (PCA) enabled simple discrimination of the samples based on their volatile profiles. This work shows the potential of SPME-GC-MS coupled with multivariant analysis to discriminate between samples of different geographical and botanical origins and form the basis for development of authentication methods of green algae products, including seasonings.

  4. Use of Volatile Tracers to Determine the Contribution ofEnvironment Tobacco Smoke to Concentrations of Volatile Organic Compoundsin Smoking Environments

    Energy Technology Data Exchange (ETDEWEB)

    Hodgson, A.T.; Daisey, J.M.; Alevantis, L.E.; Mahanama, K.R.R.; Ten Brinke, J.

    1995-12-01

    Three volatile nitrogen-containing compounds, 3-ethenylpyridine (3-EP), pyridine and pyrrole, were investigated as potential tracers for determining the contribution of environmental tobacco smoke (ETS) to concentrations of volatile organic compounds (VOCs) in indoor environments with smoking. The source emission rates of the three tracers and ten selected VOCs in ETS were first measured in a room-size environmental chamber for a market-weighted selection of six commercial cigarettes. The ratios of the emission rates of the tracers to the emission rates of the selected VOCs were calculated and compared among the six brands. The utility of the tracers was then evaluated in a field study conducted in five office buildings. Samples for VOCs were collected in designated smoking areas and adjoining non-smoking areas, air change rates were measured, and smoking rates were documented. Concentrations of the three tracers in the smoking areas were calculated using a mass-balance model and compared to their measured concentrations. Based on this comparison, 3-EP was selected as the most suitable tracer for the volatile components of ETS, although pyrrole is also potentially useful. Using 3-EP as the tracer, the contributions of ETS to the measured concentrations of the selected VOCs in the smoking areas were estimated by apportionment. ETS was estimated to contribute 57 to 84 percent (4.1 to 26 pg m{sup -3}) of the formaldehyde concentrations, 44 to 69 percent (0.9 to 5.8 pg m{sup -3}) of the 2-butanone concentrations, 37 to 58 percent (1.3 to 8.2 pg m{sup -3}) of the benzene concentrations, and 20 to 69 percent (0.5 to 3.0 pg m{sup -3}) of the styrene concentrations. The fractional contributions of ETS to the concentrations of acetone, toluene, ethylbenzene, xylene isomers and d-limonene were all less than 50 percent.

  5. Overcoming problems of density and thickness measurements in FTIR volatile determinations: a spectroscopic approach

    Science.gov (United States)

    Agrinier, Pierre; Jendrzejewski, Nathalie

    The Beer-Lambert law is traditionally used to determine water and carbon concentrations in glasses from their infrared (IR) spectra. In practice, this method requires estimation of the thickness and density of the glass as well as the calibration of the molecular absorptivities of the species concerned. All of these parameters can be sources of practical difficulties and analytical uncertainty. These weaknesses in the application of the Beer-Lambert law have been overcome by an empirical analysis of the infrared spectra. Using a set of 292 spectra obtained on 113 natural and experimental tholeiitic glasses (SiO2 48.5-51wt% water contents 0-4000ppm H2O), it can be shown that the thickness-density (ρd) product of a glass sample can be directly and reliably inferred from its IR spectrum. This allows the Beer-Lambert law to be rewritten. The new form no longer requires thickness or density estimations to determine volatile contents. Moreover, if needed, the thickness of the glass slab can also be accurately determined from the IR spectra. This new method is developed for quantitative determination of water concentrations in MORB glasses but can also be applied to any minor species (carbon, sulfur, etc.) provided it is active in the IR domain and that a suitable independent frequency of IR absorption can be identified. Precision is about 60ppm H2O on O-H- contents. This method, tested on natural and experimental MORB-type glasses, can be applied to any chemical composition provided a set of reference spectra is available.

  6. Determination of tobacco smoking influence on volatile organic compounds constituent by indoor tobacco smoking simulation experiment

    Science.gov (United States)

    Xie, Juexin; Wang, Xingming; Sheng, Guoying; Bi, Xinhui; Fu, Jiamo

    Tobacco smoking simulation experiment was conducted in a test room under different conditions such as cigarette brands, smoking number, and post-smoke decay in forced ventilation or in closed indoor environments. Thirty-seven chemical species were targeted and monitored, including volatile organic compounds (VOCs) and environmental tobacco smoke (ETS) markers. The results indicate that benzene, d-limonene, styrene, m-ethyltoluene and 1,2,4/1,3,5-trimethylbenzene are correlated well with ETS markers, but toluene, xylene, and ethylbenzene are not evidently correlated with ETS markers because there are some potential indoor sources of these compounds. 2,5-dimethylfuran is considered to be a better ETS marker due to the relative stability in different cigarette brands and a good relationship with other ETS markers. The VOCs concentrations emitted by tobacco smoking were linearly associated with the number of cigarettes consumed, and different behaviors were observed in closed indoor environment, of which ETS markers, d-limonene, styrene, trimethylbenzene, etc. decayed fast, whereas benzene, toluene, xylene, ethylbenzene, etc. decayed slowly and even increased in primary periods of the decay; hence ETS exposure in closed environments is believed to be more dangerous. VOCs concentrations and the relative percentage constituent of ETS markers of different brand cigarettes emissions vary largely, but the relative percentage constituent of ETS markers for the same brand cigarette emissions is similar.

  7. Position for determining gas-phase volatile organic compound concentrations in transuranic waste containers. Revision 2

    Energy Technology Data Exchange (ETDEWEB)

    Connolly, M.J.; Liekhus, K.J. [Lockheed Martin Idaho Technologies Co., Idaho Falls, ID (United States). Idaho National Engineering and Environmental Lab.; Djordjevic, S.M.; Loehr, C.A.; Spangler, L.R. [Benchmark Environmental Corp. (United States)

    1998-06-01

    In the conditional no-migration determination (NMD) for the test phase of the Waste Isolation Pilot Plant (WIPP), the US Environmental Protection Agency (EPA) imposed certain conditions on the US Department of Energy (DOE) regarding gas phase volatile organic compound (VOC) concentrations in the void space of transuranic (TRU) waste containers. Specifically, the EPA required the DOE to ensure that each waste container has no layer of confinement that contains flammable mixtures of gases or mixtures of gases that could become flammable when mixed with air. The EPA also required that sampling of the headspace of waste containers outside inner layers of confinement be representative of the entire void space of the container. The EPA stated that all layers of confinement in a container would have to be sampled until DOE can demonstrate to the EPA that sampling of all layers is either unnecessary or can be safely reduced. A test program was conducted at the Idaho National Engineering and Environmental Laboratory (INEEL) to demonstrate that the gas phase VOC concentration in the void space of each layer of confinement in vented drums can be estimated from measured drum headspace using a theoretical transport model and that sampling of each layer of confinement is unnecessary. This report summarizes the studies performed in the INEEL test program and extends them for the purpose of developing a methodology for determining gas phase VOC concentrations in both vented and unvented TRU waste containers. The methodology specifies conditions under which waste drum headspace gases can be said to be representative of drum gases as a whole and describes a method for predicting drum concentrations in situations where the headspace concentration is not representative. The methodology addresses the approach for determining the drum VOC gas content for two purposes: operational period drum handling and operational period no-migration calculations.

  8. Determination of volatile organic compounds in river water by solid phase extraction and gas chromatography

    Institute of Scientific and Technical Information of China (English)

    M. A. Mottaleb; M. Z. Abedin; M. S. Islam

    2004-01-01

    A simple, rapid, and reproducible method is described employing solid-phase extraction(SPE) using dichloromethane followed by gas chromatography(GC) with flame ionization detection(FID) for determination of volatile organic compound(VOC) from the Buriganga River water of Bangladesh. The method was applied to detect the benzene, toluene, ethylbenzene, xylene and cumene(BTEXC) in the sample collected from the surface or 15 cm depth of water. Two-hundred ml of n-hexane-pretreated and filtered water samples were applied directly to a C18 SPE column. BTEXC were extracted with dichloromethane and average concentrations were obtained as 0.104 to 0.372 (g/ml. The highest concentration of benzene was found as 0.372 (g/ml with a relative standard deviation(RSD) of 6.2%, and cumene was not detected. Factors influencing SPE e.g., adsorbent types, sample load volume, eluting solvent, headspace and temperatures, were investigated. A cartridge containing a C18 adsorbent and using dichloromethane gave better performance for extraction of BTEXC from water.Average recoveries exceeding 90% could be achieved for cumene at 4℃with a 2.7%RSD

  9. Plant volatiles, rather than light, determine the nocturnal behavior of a caterpillar.

    Directory of Open Access Journals (Sweden)

    Kaori Shiojiri

    2006-06-01

    Full Text Available Although many organisms show daily rhythms in their activity patterns, the mechanistic causes of these patterns are poorly understood. Here we show that host plant volatiles affect the nocturnal behavior of the caterpillar Mythimna separata. Irrespective of light status, the caterpillars behaved as if they were in the dark when exposed to volatiles emitted from host plants (either uninfested or infested by conspecific larvae in the dark. Likewise, irrespective of light status, the caterpillars behaved as if they were in the light when exposed to volatiles emitted from plants in the light. Caterpillars apparently utilize plant volatile information to sense their environment and modulate their daily activity patterns, thereby potentially avoiding the threat of parasitism.

  10. Determination of organic chemicals in human whole blood: preliminary method development for volatile organics

    Energy Technology Data Exchange (ETDEWEB)

    Cramer, P.H.; Boggess, K.E.; Hosenfeld, J.M.; Remmers, J.C.; Breen, J.J.; Robinson, P.E.; Stroup, C.

    1988-04-01

    This article introduces a method for the detection and confirmation of selected volatile organics at parts-per-trillion (ppt) levels in whole human blood. Intended for routine use, the method consists of a dynamic headspace purge of water-diluted blood where a carrier gas sweeps the surface of the sample and removes a quantifiable amount of the volatile organics from the blood and into an adsorbent trap. The organics are thermally desorbed form the adsorbent trap and onto the analytical column in a gas-chromatographic/mass-spectrometric (GC/MS) system where limited mass-scan data are taken for qualitative and quantitative identification. The method can be employed for compounds normally defined as volatile organics, such as those on the EPA priority-pollutant-volatiles list. Method validation results and limited population-survey results are also presented here.

  11. [Determination of Alcoholysis Degree and Volatile Matter of Poly-Vinyl Alcohol Using Diffuse-Reflection Near Infrared Spectroscopy].

    Science.gov (United States)

    Xie, Jin-chun; Yuan, Hong-fu; Yan, Xiang-jun; Zhao, Xin-liang; Song, Chun-feng; Wang, Xiao-ming; Li, Xiao-yu

    2016-01-01

    A new method using reflection NIR technology was developed to determine the alcoholysis degree and volatile matter of Poly-vinyl alcohol (PVA). 120 samples were used in this research. NIR spectra of the sample were scanned by the spectrometer from 1 000 to 1 800 nm. The alcoholysis degree and volatile matter were determined by the national standard method of volumetric and gravimetric method respectivily. Partial least squares (PLS1) was used to establish the quantitative correction model of alcoholysis degree and volatile matter of PVA. The corrected relationship (Rc) of alcoholysis degree and volatile matter was 0.976 and 0.981 respectively. The corrected standard deviation(SEC) was 0.176 and 0.197. The predicted relationship (R(p)) was 0.967 and 0.969. The predicted deviation(SEP) was 0.202 and 0.193. The test for actual samples showed that the NIR method was fitted for the requirement of PVA analysis.

  12. DETERMINATION AND CLASSIFICATION OF VOLATILE COMPOUNDS OF PASTIRMA USING SOLID PHASE MICROEXTRACTION/GAS CHROMATOGRAPHY/MASS SPECTROMETRY

    Directory of Open Access Journals (Sweden)

    Eda Demirok

    2013-10-01

    Full Text Available Pastırma, a traditional dry cured Turkish meat product, has a great number of specific aroma compounds, which occur as a result of lipid oxidation, protein degradation and formulation of çemen paste. These compounds give characteristic flavor to pastırma and the main objective of this study was to determine the nature of these compounds. Fifty-eight volatile compounds, grouped into nine chemical classes were identified using solid phase microextraction technique (SPME coupled to gas chromatography/mass spectrometry (GC-MS. Aldehydes, mostly lipid oxidation products, were determined as the major chemical group, representing 17.54-78.02% of total volatile compounds. The major volatile aldehyde was hexanal (2.36-55.41%, followed by 2-methyl-2-butenal (0.97-14.69% and then heptanal (0.29-4.77%. Sulfur compounds possibly derived from spices or formed by proteolysis of sulfur-containing amino acids, were the second most abundant group, with concentrations ranging between 6.04 and 50.60%. Other important volatile compounds of pastırma were aliphatic hydrocarbons, aromatic ketones, hydrocarbons, esters, alcohols, acids, terpenes, and furans.

  13. Determination of tetrachloroethylene and other volatile halogenated organic compounds in oil wastes by headspace SPME GC-MS

    Energy Technology Data Exchange (ETDEWEB)

    Fabbri, D.; Bezzi, R.; Torri, C.; Galletti, P.; Tagliavini, E. [Bologna Univ., Ravenna (Italy). Lab. of Chemistry, C.I.R.S.A

    2007-09-15

    Oil wastes and slops are complex mixtures of hydrocarbons, which may contain a variety of contaminants including tetrachloroethylene (perchloroethylene, PCE) and other volatile halogenated organic compounds (VHOCs). The analytical determination of PCE at trace levels in petroleum-derived matrices is difficult to carry out in the presence of large amounts of hydrocarbon matrix components. In the following study, we demonstrate that headspace solid-phase microextraction (HS-SPME) combined with GC-MS analysis can be applied for the rapid measurement of PCE concentration in oil samples. The HS-SPME method was developed using liquid paraffin as matrix matching reference material for external and internal calibration and optimisation of experimental parameters. The limit of quantitation was 0.05 mg kg{sup -1}, and linearity was established up to 25 mg kg{sup -1}. The HS-SPME method was extended to several VHOCs, including trichloroethylene (TCE) in different matrices and was applied to the quantitative analysis of PCE and TCE in real samples.

  14. Determination of Volatiles by Odor Activity Value and Phenolics of cv. Ayvalik Early-Harvest Olive Oil.

    Science.gov (United States)

    Guclu, Gamze; Sevindik, Onur; Kelebek, Hasim; Selli, Serkan

    2016-06-24

    Ayvalik is an important olive cultivar producing high quality oils in Turkey. In the present study, volatile and phenolic compositions of early-harvest extra virgin olive oil (cv. Ayvalik) were determined. The solvent-assisted flavor evaporation (SAFE) technique was used for the extraction of volatile components. The aromatic extract obtained by SAFE was representative of the olive oil odor. A total of 32 aroma compounds, including alcohols, aldehydes, terpenes, esters, and an acid, were identified in the olive oil. Aldehydes and alcohols were qualitatively and quantitatively the most dominant volatiles in the oil sample. Of these, six volatile components presented odor activity values (OAVs) greater than one, with (Z)-3-hexenal (green), hexanal (green-sweet) and nonanal (fatty-pungent) being those with the highest OAVs in olive oil. A total of 14 phenolic compounds were identified and quantified by liquid chromatography combined with a diode array detector and ion spray mass spectrometry. The major phenolic compounds were found as 3,4-DHPEA-EDA, 3,4-DHPEA-EA and p-HPEA-EDA.

  15. Determination of Volatiles by Odor Activity Value and Phenolics of cv. Ayvalik Early-Harvest Olive Oil

    Science.gov (United States)

    Guclu, Gamze; Sevindik, Onur; Kelebek, Hasim; Selli, Serkan

    2016-01-01

    Ayvalik is an important olive cultivar producing high quality oils in Turkey. In the present study, volatile and phenolic compositions of early-harvest extra virgin olive oil (cv. Ayvalik) were determined. The solvent-assisted flavor evaporation (SAFE) technique was used for the extraction of volatile components. The aromatic extract obtained by SAFE was representative of the olive oil odor. A total of 32 aroma compounds, including alcohols, aldehydes, terpenes, esters, and an acid, were identified in the olive oil. Aldehydes and alcohols were qualitatively and quantitatively the most dominant volatiles in the oil sample. Of these, six volatile components presented odor activity values (OAVs) greater than one, with (Z)-3-hexenal (green), hexanal (green-sweet) and nonanal (fatty-pungent) being those with the highest OAVs in olive oil. A total of 14 phenolic compounds were identified and quantified by liquid chromatography combined with a diode array detector and ion spray mass spectrometry. The major phenolic compounds were found as 3,4-DHPEA-EDA, 3,4-DHPEA-EA and p-HPEA-EDA. PMID:28231141

  16. Determination of Volatiles by Odor Activity Value and Phenolics of cv. Ayvalik Early-Harvest Olive Oil

    Directory of Open Access Journals (Sweden)

    Gamze Guclu

    2016-06-01

    Full Text Available Ayvalik is an important olive cultivar producing high quality oils in Turkey. In the present study, volatile and phenolic compositions of early-harvest extra virgin olive oil (cv. Ayvalik were determined. The solvent-assisted flavor evaporation (SAFE technique was used for the extraction of volatile components. The aromatic extract obtained by SAFE was representative of the olive oil odor. A total of 32 aroma compounds, including alcohols, aldehydes, terpenes, esters, and an acid, were identified in the olive oil. Aldehydes and alcohols were qualitatively and quantitatively the most dominant volatiles in the oil sample. Of these, six volatile components presented odor activity values (OAVs greater than one, with (Z-3-hexenal (green, hexanal (green-sweet and nonanal (fatty-pungent being those with the highest OAVs in olive oil. A total of 14 phenolic compounds were identified and quantified by liquid chromatography combined with a diode array detector and ion spray mass spectrometry. The major phenolic compounds were found as 3,4-DHPEA-EDA, 3,4-DHPEA-EA and p-HPEA-EDA.

  17. A sensitive diffusion sampler for the determination of volatile organic compounds in ambient air

    Science.gov (United States)

    Uchiyama, Shigehisa; Asai, Masae; Hasegawa, Shuji

    We developed a diffusive sampling device (DSD-voc) for volatile organic compounds (VOCs) which is suitable for collection of low level VOCs and analysis with thermal desorption. This sampling device is composed of two parts, an exposure part made of a porous polytetrafluoroethylene (PTFE) filter, and an analysis part made of stainless-steel tubing. The DSD-voc collects VOCs through the mechanism of molecular diffusion. Collection is controlled by moving the adsorbent from the exposure part to the analysis part by changing the posture of the DSD-voc. Adsorbates in the DSD-voc were analyzed by GC/MS with a thermal desorption cold trap injector (TCT). The TCT has the advantage of being able to accept the entire quantity of VOCs. We connected a condenser between the DSD-voc and the trap tube to prevent moisture from freezing in the trap tube when the sampler was packed with strong adsorbent. We also examined the desorption efficiency for VOCs from several types of adsorbents (Carboxen TM 1000, Carbosieve TM G, Carbosieve S III, Carbotrap TM B, and activated carbon) over a wide range of temperatures. Carboxen 1000 was suitable for the determination of VOCs with a low boiling point range, from CFC12 to hexane, while Carbotrap B was suitable for VOCs from hexane to 1,4-dichlorobenzene. The limits of detection with Carboxen 1000 and Carbotrap B were 0.036-0.046 and 0.0035-0.014 ppb, respectively, for a sampling duration of 24 h. Coefficients of variation for concentrations of major VOCs ranged from 3.8 to 14%. It is possible to estimate atmospheric VOCs at sub-parts per billion (sub-ppb), with high sensitivity, by using both adsorbents in combination.

  18. Full evaporation headspace gas chromatography for sensitive determination of high boiling point volatile organic compounds in low boiling matrices.

    Science.gov (United States)

    Mana Kialengila, Didi; Wolfs, Kris; Bugalama, John; Van Schepdael, Ann; Adams, Erwin

    2013-11-08

    Determination of volatile organic components (VOC's) is often done by static headspace gas chromatography as this technique is very robust and combines easy sample preparation with good selectivity and low detection limits. This technique is used nowadays in different applications which have in common that they have a dirty matrix which would be problematic in direct injection approaches. Headspace by nature favors the most volatile compounds, avoiding the less volatile to reach the injector and column. As a consequence, determination of a high boiling solvent in a lower boiling matrix becomes challenging. Determination of VOCs like: xylenes, cumene, N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), N,N-dimethylacetamide (DMA), N-methyl-2-pyrrolidone (NMP), 1,3-dimethyl-2-imidazolidinone (DMI), benzyl alcohol (BA) and anisole in water or water soluble products are an interesting example of the arising problems. In this work, a headspace variant called full evaporation technique is worked out and validated for the mentioned solvents. Detection limits below 0.1 μg/vial are reached with RSD values below 10%. Mean recovery values ranged from 92.5 to 110%. The optimized method was applied to determine residual DMSO in a water based cell culture and DMSO and DMA in tetracycline hydrochloride (a water soluble sample). Copyright © 2013 Elsevier B.V. All rights reserved.

  19. Simultaneous determination of volatile and non-volatile nitrosamines in processed meat products by liquid chromatography tandem mass spectrometry using atmospheric pressure chemical ionisation and electrospray ionisation.

    Science.gov (United States)

    Herrmann, S S; Duedahl-Olesen, L; Granby, K

    2014-02-21

    A sensitive, selective and generic method has been developed for the simultaneous determination of the contents (μgkg(-1) range) of both volatile nitrosamines (VNA) and non-volatile nitrosamines (NVNA) in processed meat products. The extraction procedure only requires basic laboratory equipment and a small volume of organic solvent. Separation and quantification were performed by the developed LC-(APCI/ESI)MS/MS method. The method was validated using spiked samples of three different processed meat products. Satisfactory recoveries (50-130%) and precisions (2-23%) were obtained for eight VNA and six NVNAs with LODs generally between 0.2 and 1μgkg(-1), though for a few analyte/matrix combinations higher LODs were obtained (3 to 18μgkg(-1)). The validation results show that results obtained for one meat product is not always valid for other meat products. We were not able to obtain satisfactory results for N-nitrosohydroxyproline (NHPRO), N-nitrosodibenzylamine (NDBzA) and N-nitrosodiphenylamine (NDPhA). Application of the APCI interface improved the sensitivity of the method, because of less matrix interference, and gave the method a wider scope, as some NAs were ionisable only by APCI. However, it was only possible to ionize N-nitroso-thiazolidine-4-carboxylic acid (NTCA) and N-nitroso-2-methyl-thiazolidine-4-carboxylic acid (NMTCA) by ESI. The validated method was applied for the analysis of processed meat products and contents of N-nitrosodimethylamine (NDMA), N-nitrosopyrrolidine (NPYR), N-nitrosomethylaniline (NMA), N-nitrosoproline (NPRO), NTCA, and NMTCA were found in one or several nitrite cured meat products, whereas none were detected in non-nitrite cured bacon.

  20. Determination of volatile aroma compounds of Ganoderma lucidum by gas chromatography mass spectrometry (HS-GC/MS).

    Science.gov (United States)

    Taşkın, Hatıra; Kafkas, Ebru; Çakıroğlu, Özgün; Büyükalaca, Saadet

    2013-01-01

    This study was conducted at Horticulture Department of Cukurova University, Adana, Turkey during 2010-2011. Fresh sample of Ganoderma lucidum collected from Mersin province of Turkey was used as material. Volatile aroma compounds were performed by Headspace Gas Chromatography (HS-GC/MS). Alcohols, aldehydes, acids, phenol, L-Alanine, d-Alanine, 3Methyl, 2-Butanamine, 2-Propanamine were determined. 1-Octen-3-ol (Alcohol) and 3-methyl butanal (Aldehyde) were identified as major aroma compounds.

  1. Comparison of methods for determining volatile compounds in milk, cheese, and whey powder

    Science.gov (United States)

    Solid phase microextraction (SPME) and gas chromatography-mass spectrometry (GC-MS) are commonly used for qualitative and quantitative analysis of volatile compounds in various dairy products, but conditions have to be adjusted for optimal SPME release while not generating new compounds that are abs...

  2. Determination of organic chemicals in human whole blood: Preliminary method development for volatile organics

    Energy Technology Data Exchange (ETDEWEB)

    Cramer, P.H.; Boggess, K.E.; Hosenfeld, J.M. (Midwest Research Institute, Kansas City, MO (USA)); Remmers, J.C.; Breen, J.J.; Robinson, P.E.; Stroup, C. (Environmental Protection Agency, Washington, DC (USA))

    1988-05-01

    Extensive commercial, industrial, and domestic use of volatile organic chemicals, virtually assures that the general population will be exposed to some level of this class of chemicals. Because blood interacts with the respiratory system and is a major component of the body, it is likely that the analysis of blood will show exposure to volatile organics. Monitoring of the blood in conjunction with monitoring of xenobiotic levels in urine and adipose tissue is an effective way to assess the total body burden resulting from exposure to a chemical. This article introduces a method for the detection and confirmation of selected volatile organics at parts-per-trillion (ppt) levels in whole human blood. Intended for routine use, the method consists of a dynamic headspace purge of water-diluted blood where a carrier gas sweeps the surface of the sample and removes a quantifiable amount of the volatile organics from the blood and into an adsorbent trap. The organics are thermally desorbed from the adsorbent trap and onto the analytical column in a gas-chromatographic/mass-spectrometric (GC/MS) system where limited mass-scan data are taken for qualitative and quantitative identification. Method validation results and limited population-survey results are also presented here.

  3. Determination of Selected Volatiles in Cigarette Mainstream Smoke. The CORESTA 2009 Collaborative Study and Recommended Method

    Directory of Open Access Journals (Sweden)

    Intorp M

    2014-12-01

    Full Text Available A recommended method has been developed and published by CORESTA, applicable to the quantification of selected volatiles (1,3-butadiene, isoprene, acrylonitrile, benzene, and toluene in the gas phase of cigarette mainstream smoke. The method involved smoke collection in impinger traps and detection and measurement using gas chromatography/mass spectrometry techniques.

  4. Use of Bayesian Estimates to determine the Volatility Parameter Input in the Black-Scholes and Binomial Option Pricing Models

    Directory of Open Access Journals (Sweden)

    Shu Wing Ho

    2011-12-01

    Full Text Available The valuation of options and many other derivative instruments requires an estimation of exante or forward looking volatility. This paper adopts a Bayesian approach to estimate stock price volatility. We find evidence that overall Bayesian volatility estimates more closely approximate the implied volatility of stocks derived from traded call and put options prices compared to historical volatility estimates sourced from IVolatility.com (“IVolatility”. Our evidence suggests use of the Bayesian approach to estimate volatility can provide a more accurate measure of ex-ante stock price volatility and will be useful in the pricing of derivative securities where the implied stock price volatility cannot be observed.

  5. First determination of dissolved volatiles in magmas of Mt Garet (Vanuatu arc). Origin of sulfur emissions

    Science.gov (United States)

    Floury, P.; Metrich, N.; Bertagnini, A.; Garaebiti, E.; Hidalgo, S.; Beaumais, A.; Neuville, D.

    2012-12-01

    Mt Garet, on Gaua island, is one of the active volcanoes of the Vanuatu arc in the Southwest Pacific. This 360 m high cone emerges from the lake Letas in the summit caldera of a composite volcano. Since 1962, Mt Garet produced ash and gas plumes recurrently, the last explosive events being documented in 2009 - 2010. Airborne measurements of SO2 emission rates, the only data set presently available for this volcano, were realized in 2009 and revealed a high SO2 flux of, on average, 2955 tons per day [1]. We report here the very first data on the geochemistry of the scoriae emitted in January 2010, together with analyses of major elements and volatiles (H2O, Cl, S) in crystal-hosted melt inclusions and a detailed mineralogy of the samples. The 2010 scoriae are basaltic-andesites and are more evolved that the pre-1962 basaltic lava flows of Mt Garet. Their major and trace element evolution cannot be reconciled with a single process of fractional crystallization, but suggest mixing between a pre-1962 like basalt and an evolved trachydacitic end-member. This observation strongly suggests the recent development of a small reservoir beneath Mt Garet. The plagioclases (An89-73) and clinopyroxenes (Fs5-16) display a significant chemical range but do not clearly evidence reverse zoning. The paragenesis is complemented by Fe-Ti oxides (USP39-40) and scarce olivines (Fo72.7). Some crystals are obviously inherited (e.g., An-poor plagioclase). The melt inclusions are ubiquitous but of small size in each mineral phase. Their H2O content was specifically determined using micro-Raman spectroscopy (IPGP), with a series of basaltic glass standards previously developed for Raman calibration [2]. Data and spectrum are treated following [3]. As a whole melt inclusion compositions cover the whole chemical spectrum from basalt to trachydacite. Their contents in H2O (2.7-0.8 wt%), S (1570 - Journal of Volcanology and Geothermal Research, 211-212, 36-46 [2] Mercier et al., (2009) and (2010

  6. [Determination of chemical components of volatile oil from Cuminum cyminum L. by gas chromatography-mass spectrometry].

    Science.gov (United States)

    Yan, Jian-hui; Tang, Ke-wen; Zhong, Ming; Deng, Ning-hua

    2002-11-01

    Volatile oil was extracted from Cuminum cyminum L. by using steam distillation. More than sixty peaks were separated and 49 compounds were identified by gas chromatography-mass spectrometry (GC-MS). The relative amounts of the components were determined by area normalization method. Among the 49 compounds identified, there were 16 hydrocarbons and 32 oxygenated compounds. The main compnents were cuminal and safranal (accounting for 32.26% and 24.46% respectively in the components identified). The other nine compounds with contents all over 1%, were monterpenes, sesquiterpenes, aromatic aldehydes and aromatic oxides etc. The other components with relatively small amounts were chiefly terpenes, terpenols, terpenals, terpenones, terpene esters and aromatic compounds. It is good to separate polar and apolar components in the volatile oil from Cuminum cyminum L. on the GC capillary column of moderate polarity.

  7. Method "Ethanol as Internal Standard" for determination of volatile compounds in alcohol products by gas chromatography in daily practice

    CERN Document Server

    Charapitsa, Siarhei V; Makhomet, Andrey A; Guguchkina, Tatiana I; Markovsky, Mikhail G; Yakuba, Yurii F; Kotov, Yurii N

    2016-01-01

    Recently proposed new method "Ethanol as Internal Standard" for determination of volatile compounds in alcohol products by gas chromatography (GC) is investigated from different sides including method testing on prepared standard solutions like cognac and brandy, different ethanol-water solutions and certified reference material CRM LGC5100 Whisky-Congeners. Analysis of obtained results of experimental study from four different laboratories shows that relative bias between the experimentally measured concentrations calculated in accordance with proposed method and the values of concentrations assigned during the preparation by gravimetric method for all analyzed compounds does not exceed 10 %. It is shown that relative response factors (RRF) between analyzed volatile compounds and ethanol do not depend on time of analysis and are constant for every model of GC. It is shown the possibility to use predetermined RRF in daily practice of testing laboratories and to implement this new method in the international s...

  8. Determination of volatile components in cut tobacco with gas chromatography-mass spectrometry and chemometric resolution

    Institute of Scientific and Technical Information of China (English)

    HUANG Lan-fang; WU Ming-jian; SUN Xian-jun; ZHONG Ke-jun; GUO Zi-ming; DAI Yun-hui; HUANG Ke-long; GUO Fang-qiu

    2007-01-01

    Chromatography-mass spectrometry (GC-MS) was used to analyze the volatile components of cut tobacco samples with the help of heuristic evolving latent projections (HELP). After extracting with simultaneous distillation and extraction method, the volatile components in cut tobacco were detected by GC-MS. Then the obtained original two-dimensional data were resolved into pure mass spectra and chromatograms. The qualitative analysis was performed by similarity searches in the national institute of standards and technology(NIST) mass database with the obtained pure mass spectrum of each component and the quantitative results were obtained by calculating the volume of total two-way response. The accuracy of qualitative and quantitative results were greatly improved by using the two-dimensional comprehensive information of chromatograms and mass spectra. 107 of 141 separated constituents in the total ion chromatogram of the volatile components were identified and quantified, accounting for about 88.01% of the total content. The result proves that the developed method is powerful for the analysis of complex cut tobacco samples.

  9. Determination of volatile compounds by GC-IMS to assign the quality of virgin olive oil.

    Science.gov (United States)

    Garrido-Delgado, Rocío; Dobao-Prieto, María del Mar; Arce, Lourdes; Valcárcel, Miguel

    2015-11-15

    The characterisation of different olive oil categories (extra virgin, virgin and lampante) using Ion Mobility Spectrometry (IMS) was improved by replacing the multicapillary column (MCC) with a capillary column (CC). The data obtained with MCC-IMS and CC-IMS were evaluated, studying both the global and the specific information obtained after the analysis of the volatile fraction of olive oils. A better differentiation of the oil categories was obtained employing CC vs MCC, since the classification percentage obtained with the CC-IMS was 92% as opposed to 87% obtained with MCC-IMS; although in productivity analytical terms, MCC offer a faster analysis than GC. The specific information obtained was also used to build a database, with a view to facilitating the characterization of specific attributes of olive oils. A total of 26 volatile metabolites (aldehydes, ketones, alcohols and esters) were identified. Finally, as revealed by an ANOVA test, some volatiles differed markedly in content among the different categories of oil. The data obtained confirms the potential of IMS as a reliable analytical screening technique, which can be used to assign the correct category to an olive oil sample.

  10. Determination of linear and cyclic volatile methylsiloxanes in air at a regional background site in Sweden

    Science.gov (United States)

    Kierkegaard, Amelie; McLachlan, Michael S.

    2013-12-01

    A number of volatile methylsiloxanes have been identified as environmental contaminants and several are currently the subject of detailed risk assessments due to concerns that they may be persistent, bioaccumulative and toxic in the environment. Once emitted these chemicals reside primarily in the atmosphere. Consequently, knowledge of their concentrations in air is essential to understanding their fate in the environment and any potential adverse impacts. We developed a method to analyse 4 cyclic volatile methylsiloxanes (D3, D4, D5 and D6) and 4 linear volatile methylsiloxanes (L3, L4, L5 and L6) in air at regional background levels. The method showed good repeatability (median difference between sample pairs of 2-8%) and low limits of quantification (from 3.8 pg m-3 for L3 to 320 pg m-3 for D4). However, the analysis of D3 and D4 was confounded by the transformation of D5 to these analytes on the sampling cartridge. During a sampling campaign with a daily temporal resolution between November 4 and December 14 2011, all analytes with the exception of L5 and L6 could be quantified in all samples. It was hypothesized that the ratio of the concentrations of different VMS reflected the relative strength of their emissions to the airshed due to the slow phototransformation of the VMS at high latitudes in winter. This was supported by available emissions information.

  11. Determination of refractive and volatile elements in sediment using laser ablation inductively coupled plasma mass spectrometry.

    Science.gov (United States)

    Duodu, Godfred Odame; Goonetilleke, Ashantha; Allen, Charlotte; Ayoko, Godwin A

    2015-10-22

    Wet-milling protocol was employed to produce pressed powder tablets with excellent cohesion and homogeneity suitable for laser ablation (LA) analysis of volatile and refractive elements in sediment. The influence of sample preparation on analytical performance was also investigated, including sample homogeneity, accuracy and limit of detection. Milling in volatile solvent for 40 min ensured sample is well mixed and could reasonably recover both volatile (Hg) and refractive (Zr) elements. With the exception of Cr (-52%) and Nb (+26%) major, minor and trace elements in STSD-1 and MESS-3 could be analysed within ±20% of the certified values. Comparison of the method with total digestion method using HF was tested by analysing 10 different sediment samples. The laser method recovers significantly higher amounts of analytes such as Ag, Cd, Sn and Sn than the total digestion method making it a more robust method for elements across the periodic table. LA-ICP-MS also eliminates the interferences from chemical reagents as well as the health and safety risks associated with digestion processes. Therefore, it can be considered as an enhanced method for the analysis of heterogeneous matrices such as river sediments.

  12. Use of fiber interface direct mass spectrometry for the determination of volatile flavor release from model food systems.

    Science.gov (United States)

    Springett, M B; Rozier, V; Bakker, J

    1999-03-01

    Described in this paper is a fiber interface direct headspace mass spectrometric system for the real-time measurement of flavor release. The system was optimized for the detection of the garlic aroma volatile, diallyl disulfide, from water. Parameters investigated included interface temperature, flow rate through the fiber, flow rate through the sample vessel, and sample stir rate. The delay time for detection of sample after introduction into the sample vessel was determined as 43 s. The system proved to be reliable and robust with no loss in sensitivity or contamination of the mass spectrometer over a 6 month period. The technique was applied to a homologous series of aliphatic alcohols from C(2) to C(7). Results showed that as polarity decreased with increasing chain length the release of volatile into the headspace was faster and gave a higher maximum intensity. Release of the garlic aroma volatile from different commercial mayonnaise products clearly showed a decrease in the release of diallyl disulfide as fat content increased. These results demonstrate the potential of using this technique as a tool for understanding the complex interactions that occur between flavor compounds and the bulk food matrix.

  13. Determination of refractive and volatile elements in sediment using laser ablation inductively coupled plasma mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Duodu, Godfred Odame [School of Chemistry, Physics and Mechanical Engineering, Science and Engineering Faculty, Queensland University of Technology (QUT), 2 George St, 4001, QLD (Australia); Goonetilleke, Ashantha [School of Civil Engineering and Built Environment, Science and Engineering Faculty, Queensland University of Technology (QUT), 2 George St, 4001, QLD (Australia); Allen, Charlotte [Institute for Future Environments, Queensland University of Technology (QUT), 2 George St, 4001, QLD (Australia); Ayoko, Godwin A., E-mail: g.ayoko@qut.edu.au [School of Chemistry, Physics and Mechanical Engineering, Science and Engineering Faculty, Queensland University of Technology (QUT), 2 George St, 4001, QLD (Australia)

    2015-10-22

    Wet-milling protocol was employed to produce pressed powder tablets with excellent cohesion and homogeneity suitable for laser ablation (LA) analysis of volatile and refractive elements in sediment. The influence of sample preparation on analytical performance was also investigated, including sample homogeneity, accuracy and limit of detection. Milling in volatile solvent for 40 min ensured sample is well mixed and could reasonably recover both volatile (Hg) and refractive (Zr) elements. With the exception of Cr (−52%) and Nb (+26%) major, minor and trace elements in STSD-1 and MESS-3 could be analysed within ±20% of the certified values. Comparison of the method with total digestion method using HF was tested by analysing 10 different sediment samples. The laser method recovers significantly higher amounts of analytes such as Ag, Cd, Sn and Sn than the total digestion method making it a more robust method for elements across the periodic table. LA-ICP-MS also eliminates the interferences from chemical reagents as well as the health and safety risks associated with digestion processes. Therefore, it can be considered as an enhanced method for the analysis of heterogeneous matrices such as river sediments. - Highlights: • Wet milling was used to produce pressed tablet sediment for LA-ICP-MS analysis. • Milling was effective for refractive elements with narrow range of particle size. • This is the first use of LA-ICP-MS for Hg analysis in sediment samples. • Acceptable accuracy and precision were obtained for most of the elements studied. • Detection limits down to parts per trillion were observed for some elements.

  14. Determination of volatile compounds in Grenache wines in relation with different terroirs in the Rhone Valley.

    Science.gov (United States)

    Sabon, Isabelle; De Revel, Gilles; Kotseridis, Yorgos; Bertrand, Alain

    2002-10-23

    This paper describes the study of 19 wines of the Grenache Noir cultivar obtained from representative soils of the Rhone Valley according to their geographical site, climatic conditions, hydrological regulation, and soil profile. Among the volatile compounds analyzed by GC/MS/FID, the concentrations of the varietal compounds (i.e., beta-damascenone, beta-ionone, and geraniol) and those of the compounds without direct influence on the wine aroma (i.e., hexenols and methanol) indicated the existence of two groups of wines. These concentrations were correlated with grape maturity due to the ecosystem and particularly the soil.

  15. Comparision of Methods Used for Determination of Total Volatile Basic Nitrogen (TVB-N) in Rainbow Trout (Oncorhynchus mykiss)

    OpenAIRE

    ÖZOĞUL, Fatih; Özoğul, Yeşim

    2000-01-01

    TVB-N (total volatile basic nitrogen) concentration in fish muscle was used as an index of freshness quality to compare the spoilage of rainbow trout wrapped in cling film and in aluminium foil. TVB-N levels in different muscle tissue and in the whole fish were measured every two days for a period of 16 days at 4-6°C. In addition, three different methods of determining of TVB-N were evaluated in terms of sensitivity, reliability, speed, and cost. Regardless of the method of analysis, there wa...

  16. Plant defense phenotypes determine the consequences of volatile emission for individuals and neighbors

    Science.gov (United States)

    Schuman, Meredith C; Allmann, Silke; Baldwin, Ian T

    2015-01-01

    Plants are at the trophic base of terrestrial ecosystems, and the diversity of plant species in an ecosystem is a principle determinant of community structure. This may arise from diverse functional traits among species. In fact, genetic diversity within species can have similarly large effects. However, studies of intraspecific genetic diversity have used genotypes varying in several complex traits, obscuring the specific phenotypic variation responsible for community-level effects. Using lines of the wild tobacco Nicotiana attenuata genetically altered in specific well-characterized defense traits and planted into experimental populations in their native habitat, we investigated community-level effects of trait diversity in populations of otherwise isogenic plants. We conclude that the frequency of defense traits in a population can determine the outcomes of these traits for individuals. Furthermore, our results suggest that some ecosystem-level services afforded by genetically diverse plant populations could be recaptured in intensive monocultures engineered to be functionally diverse. DOI: http://dx.doi.org/10.7554/eLife.04490.001 PMID:25873033

  17. Model Experiments for the Determination of Airflow in Large Spaces

    DEFF Research Database (Denmark)

    Nielsen, Peter V.

    Model experiments are one of the methods used for the determination of airflow in large spaces. This paper will discuss the formation of the governing dimensionless numbers. It is shown that experiments with a reduced scale often will necessitate a fully developed turbulence level of the flow....... Details of the flow from supply openings are very important for the determination of room air distribution. It is in some cases possible to make a simplified supply opening for the model experiment....

  18. Determination of Volatile Organic Compounds in the Atmosphere Using Two Complementary Analysis Techniques.

    Science.gov (United States)

    Alonso, L; Durana, N; Navazo, M; García, J A; Ilardia, J L

    1999-08-01

    During a preliminary field campaign of volatile organic compound (VOC) measurements carried out in an urban area, two complementary analysis techniques were applied to establish the technical and scientific bases for a strategy to monitor and control VOCs and photochemical oxidants in the Autonomous Community of the Basque Country. Integrated sampling was conducted using Tenax sorbent tubes and laboratory analysis by gas chromatography, and grab sampling and in situ analysis also were conducted using a portable gas chromatograph. With the first technique, monocyclic aromatic hydrocarbons appeared as the compounds with the higher mean concentrations. The second technique allowed the systematic analysis of eight chlorinated and aromatic hydrocarbons. Results of comparing both techniques, as well as the additional information obtained with the second technique, are included.

  19. Profiling of Volatile Impurities in Tetramethylenedisulfotetramine (TETS) for Synthetic-Route Determination

    Energy Technology Data Exchange (ETDEWEB)

    Fraga, Carlos G.; Wahl, Jon H.; Nunez, Stefanie P.

    2011-07-15

    This study investigated the feasibility of using volatile impurities from the rodenticide tetramethylenedisulfotetramine (TETS) for the discrimination of TETS produced by three synthetic routes. Each route was used to make one batch of TETS by reacting sulfamide with one of three formaldehyde analogs in the presence of either trifluroacetic acid (TFA) or hydrochloric acid. Ten impurities useful for differentiating the three TETS batches were sampled and tentatively identified by headspace solid-phase microextraction comprehensive two-dimensional gas chromatography-mass spectrometry (HS-SPME/GC x CG-MS). Of the ten identified impurities, the alkyl trifluoroacetate and alkyl chloride impurities distinguished TETS routes based on their use of either TFA or HCl as catalyst. On the other hand, four 6-carbon ketone impurities appeared to be batch specific rather than route specific and hence potentially useful for sample matching. Interestingly, 1,3,5-trioxane was not found in the TETS batch where it was used as a reactant, but instead was found in the two batches that did not have 1,3,5-trioxane as the reactant. In summary, the limited work discussed in this paper supports: (1) the feasibility of sampling and detecting volatile organic impurities from a solid chemical-threat agent, (2) the probable forensic benefit of catalysts acting as reactants in side reactions, (3) the uniqueness of a synthetic batch’s impurity profile for potential sample matching, and (4) the possibility that some impurities, such as formaldehyde analogs, are not forensically helpful and may lead to an incorrect estimate about the synthetic route if not supported by sound chemical knowledge.

  20. DETERMINATION OF SATURATION VAPOR PRESSURE OF LOW VOLATILE SUBSTANCES THROUGH THE STUDY OF EVAPORATION RATE BY THERMOGRAVIMETRIC ANALYSIS

    Directory of Open Access Journals (Sweden)

    R. V. Ralys

    2015-11-01

    Full Text Available Subject of Study.Research of vapor pressure of low volatile substances is a complicated problem due to both direct experimental implementation complexity and, most significantly, the issues faced correctness of the analysis and processing of experimental data. That is why it is usually required engaging the reference substances (with vapor pressures well studied. The latter drastically reduces the effectiveness of the experimental methods used and narrows their applicability. The paper deals with an approach to the evaporation process description (sublimation of low volatile substances based on molecular kinetic description in view of diffusive and convection processes. The proposed approach relies on experimental thermogravimetricfindingsina wide range of temperatures, flow rates ofthe purge gas and time. Method. A new approach is based on the calculation of the vapor pressure and uses the data about the speed of evaporation by thermogravimetric analysis depending on the temperature, the flow rate of the purge gas, and the evaporation time. The basis for calculation is the diffusion-kinetic description of the process of evaporation (mass loss of the substance from the exposed surface. The method is applicable to determine the thermodynamic characteristics for both the evaporation (the equilibrium liquid - vapor and sublimation (the equilibrium solid - vapor. We proposed the appropriate method of the experiment and analysis of its data in order to find the saturated vapor pressure of individual substances of low volatility. Main Results. The method has been tested on substances with insufficiently reliable and complete study of the thermodynamic characteristics but, despite this, are often used (because of the other data limitations as reference ones. The vaporization process (liquid-vapor has been studied for di-n-butyl phthalate C16H22O4 at 323,15–443,15 К, and sublimation for benzoic acid C7H6O2at 303,15–183,15 К. Both processes have

  1. New approach on volatile contents determination in silicate melt inclusions: A coupling X-ray microtomography and geochemical approach in Los Humeros caldera complex (Eastern Mexican Volcanic Belt)

    Science.gov (United States)

    Creon, L.; Levresse, G.; Carrasco Nuñez, G.

    2016-12-01

    Volatile contents and magma degassing behavior are known to affect the style, frequency, and intensity of near-surface magmatic processes. For this reason, much effort have been devoted to characterize the volatile evolution of shallow magmatic systems to better constrain volcanic history. Silicate melt inclusions (SMI) represent samples of melt that were isolated from the bulk magma at depth, thus preserving the PTX conditions of the pre-eruptive material. SMI are often affected by the formation of a bubble after trapping; this is a natural consequence of the PVTX properties of crystal-melt-volatile systems. Previous workers have recognized that bubble formation is an obstacle, which affects the interpretation of SMI trapping conditions based only on analysis of the glass phase. Indeed, they explained that bubbles can contain a significant percentage of the volatiles, particularly for those with low solubility in the melt (e.g. CO2). In this study, we propose to define the pre-eruptive PTX conditions of Los Humeros magma chamber using SMI from the various eruption events within 460 and 30 Ka. An innovative analytical coupling has been used in order to determine: (1) the volume of the SMI glass and bubble, using high resolution 3D X-ray microtomography; (2) the density and composition of the bubbles, using Raman spectroscopy; (3) the volatile element contents in glass, using NanoSIMS; and, (4) the major elements composition of the glass, using EPMA. The recalculated volatile concentrations of the total SMI (glass + bubble), illustrate clearly that the volatile content determinations using only the glass phase, underestimate drastically the total volatile content and therefore induce significant error on the determination of the pre-eruptive volcanic budget and on the constrain on the volcanic and thermal history. This study had moreover highlighted the complex evolution of Los Humeros composite magma chamber and, gave constrains for geothermal exploration purpose.

  2. Quantitative determination of volatile organic compounds (VOC) in milk by multiple dynamic headspace extraction and GC-MS.

    Science.gov (United States)

    Ciccioli, Paolo; Brancaleoni, Enzo; Frattoni, Massimiliano; Fedele, Vincenzo; Claps, Salvatore; Signorelli, Federica

    2004-01-01

    A method for the accurate determination of volatile organic compounds (VOC) in milk samples has been developed and tested. It combines multiple dynamic headspace extraction with GC-MS. Absolute amounts of VOC in the liquid phase are obtained by determining the first order kinetic dependence of the stepwise extraction of the analytes and internal standards from the liquid matrix. Compounds released from milk were collected on a train of traps filled with different solid sorbents to cover all components having a number of carbon atoms ranging from 4 to 15. They were analysed by GC-MS after thermal desorption of VOC from the collecting traps. Quantification of VOC in milk was performed using deuterated compounds as internal standards. The method was used to follow seasonal variations of monoterpenes in goat milk and to detect the impact of air pollution on the quality of milk.

  3. Headspace solid phase microextraction (HSSPME) for the determination of volatile and semivolatile pollutants in soils

    Energy Technology Data Exchange (ETDEWEB)

    Llompart, Maria [Departamento de Quimica Analitica Nutricion y Bromatologia, Facultad de Quimica, Universidad de Santiago de Compostela, E-15706 Santiago de Compostela (Spain); Li, Ken; Fingas, Merv [Emergencies Science Division, Environment Canada, Environmental Technology Centre, 3439 River Road, Ottawa, ON (Canada)

    1999-02-08

    We have investigated the use of headspace solid phase microextraction (HSSPME) as a sample concentration and preparation technique for the analysis of volatile and semivolatile pollutants in soil samples. Soil samples were suspended in solvent and the SPME fibre suspended in the headspace above the slurry. Finally, the fibre was desorbed in the Gas Chromatograph (GC) injection port and the analysis of the samples was carried out. Since the transfer of contaminants from the soil to the SPME fibre involves four separate phases (soil-solvent-headspace and fibre coating), parameters affecting the distribution of the analytes were investigated. Using a well-aged artificially spiked garden soil, different solvents (both organic and aqueous) were used to enhance the release of the contaminants from the solid matrix to the headspace. It was found that simple addition of water is adequate for the purpose of analysing the target volatile organic chemicals (VOCs) in soil. The addition of 1 ml of water to 1 g of soil yielded maximum response. Without water addition, the target VOCs were almost not released from the matrix and a poor response was observed. The effect of headspace volume on response as well as the addition of salt were also investigated. Comparison studies between conventional static headspace (HS) at high temperature (95C) and the new technology HSSPME at room temperature (=20C) were performed. The results obtained with both techniques were in good agreement. HSSPME precision and linearity were found to be better than automated headspace method and HSSPME also produced a significant enhancement in response. The detection and quantification limits for the target VOCs in soils were in the sub-ng g{sup -1} level. Finally, we tried to extend the applicability of the method to the analysis of semivolatiles. For these studies, two natural soils contaminated with diesel fuel and wood preservative, as well as a standard urban dust contaminated with polyaromatic

  4. Determination of the volatile fraction of phosphorus flame retardants in cushioning foam of upholstered furniture: towards respiratory exposure assessment.

    Science.gov (United States)

    Ghislain, Mylène; Beigbeder, Joana; Dumazert, Loïc; Lopez-Cuesta, José-Marie; Lounis, Mohammed; Leconte, Stéphane; Desauziers, Valérie

    2016-10-01

    The purpose of this paper was to highlight potential exposure in indoor air to phosphorus flame retardants (PFRs) due to their use in upholstered furniture. For that, an analytical method of PFRs by headspace coupled to solid-phase micro-extraction (HS-SPME) was developed on cushioning foams in order to determine the PFRs' volatile fraction in the material. Tests on model foams proved the feasibility of the method. The average repeatability (RSD) is 6.3 % and the limits of detection range from 0.33 to 1.29 μg g(-1) of foam, depending on the PFRs. Results showed that some PFRs can actually be emitted in air, leading to a potential risk of exposure by inhalation. The volatile fraction can be high (up to 98 % of the total PFRs amount) and depends on the physicochemical properties of flame retardants, on the textural characteristics of the materials and on the temperature. The methodology developed for cushioning foams could be further applied to other types of materials and can be used to rate them according to their potential releases of phosphorus flame retardants.

  5. The Determinants of won/dollar Exchange Rate Volatility and Policy Recommendations

    Directory of Open Access Journals (Sweden)

    Chae-Shick Chung

    1998-09-01

    Full Text Available This thesis analyzed the feature and different points of the changing of the exchange rate of Korea won against US dollar, then discussed the direction of the completion of Korea exchange rate system. The prediction result of the model GARCH which vividly shows the phenomenon of the auto-regression of the exchange rate has indicated the level of the exchange rate yesterday could explain the circumstance of the change of exchange rate today. Meanwhile, the policy of the US exchange rate will affect the exchange rate of Korea won against US dollar and the volatility of foreign exchange rate. In the present situation of Korean economy in which the liberalization of capital and the independence of the central bank has been established, the choosing range of the exchange system could only be completely changeable exchange rate system or exchange rate system of multilateral arrangement like Europe. However, in terms of the condition of the world economy, the introduction of the latter system is too early. There is an idea that under the changeable exchange rate system which is the only choice, it is the right time to activate the main body of private economy, the financial derivatives market in which the exchange risk could be trade-off. Government should work on and create a policy that would be able to satisfy the expectations of the market participants.

  6. Determination of volatile organic compounds pollution sources in malaysian drinking water using multivariate analysis.

    Science.gov (United States)

    Soh, Shiau-Chian; Abdullah, Md Pauzi

    2007-01-01

    A field investigation was conducted at all water treatment plants throughout 11 states and Federal Territory in Peninsular Malaysia. The sampling points in this study include treatment plant operation, service reservoir outlet and auxiliary outlet point at the water pipelines. Analysis was performed by solid phase micro-extraction technique with a 100 microm polydimethylsiloxane fibre using gas chromatography with mass spectrometry detection to analyse 54 volatile organic compounds (VOCs) of different chemical families in drinking water. The concentration of VOCs ranged from undetectable to 230.2 microg/l. Among all of the VOCs species, chloroform has the highest concentration and was detected in all drinking water samples. Average concentrations of total trihalomethanes (THMs) were almost similar among all states which were in the range of 28.4--33.0 microg/l. Apart from THMs, other abundant compounds detected were cis and trans-1,2-dichloroethylene, trichloroethylene, 1,2-dibromoethane, benzene, toluene, ethylbenzene, chlorobenzene, 1,4-dichlorobenzene and 1,2-dichloro - benzene. Principal component analysis (PCA) with the aid of varimax rotation, and parallel factor analysis (PARAFAC) method were used to statistically verify the correlation between VOCs and the source of pollution. The multivariate analysis pointed out that the maintenance of auxiliary pipelines in the distribution systems is vital as it can become significant point source pollution to Malaysian drinking water.

  7. Determination of cyclic volatile methylsiloxanes in biota with a purge and trap method.

    Science.gov (United States)

    Kierkegaard, Amelie; Adolfsson-Erici, Margaretha; McLachlan, Michael S

    2010-11-15

    The three cyclic volatile methylsiloxanes (cVMS), octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5), and dodecamethylcyclohexasiloxane (D6), are recently identified environmental contaminants. Methods for the trace analysis of these chemicals in environmental matrices are required. A purge and trap method to prepare highly purified sample extracts with a low risk of sample contamination is presented. Without prior homogenization, the sample is heated in water, and the cVMS are purged from the slurry and trapped on an Isolute ENV+ cartridge. They are subsequently eluted with n-hexane and analyzed with GC/MS. The method was tested for eight different matrices including ragworms, muscle tissue from lean and lipid-rich fish, cod liver, and seal blubber. Analyte recoveries were consistent within and between matrices, averaging 79%, 68%, and 56% for D4, D5, and D6, respectively. Good control of blank levels resulted in limits of quantification of 1.5, 0.6, and 0.6 ng/g wet weight. The repeatability was 12% (D5) and 15% (D6) at concentrations 9 and 2 times above the LOQ. The method was applied to analyze cVMS in fish from Swedish lakes, demonstrating that contamination in fish as a result of long-range atmospheric transport is low as compared to contamination from local sources.

  8. Determination of elemental composition of volatile organic compounds from Chinese rose oil by spectral accuracy and mass accuracy.

    Science.gov (United States)

    Zhou, Wei; Zhang, Yaheng; Xu, Hongliang; Gu, Ming

    2011-10-30

    Elemental composition determination of volatile organic compounds through high mass accuracy and isotope pattern matching could not be routinely achieved with a unit-mass resolution mass spectrometer until the recent development of the comprehensive instrument line-shape calibration technology. Through this unique technology, both m/z values and mass spectral peak shapes are calibrated simultaneously. Of fundamental importance is that calibrated mass spectra have symmetric and mathematically known peak shapes, which makes it possible to deconvolute overlapped monoisotopes and their (13)C-isotope peaks and achieve accurate mass measurements. The key experimental requirements for the measurements are to acquire true raw data in a profile or continuum mode with the acquisition threshold set to zero. A total of 13 ions from Chinese rose oil were analyzed with internal calibration. Most of the ions produced high mass accuracy of better than 5 mDa and high spectral accuracy of better than 99%. These results allow five tested ions to be identified with unique elemental compositions and the other eight ions to be determined as a top match from multiple candidates based on spectral accuracy. One of them, a coeluted component (Nerol) with m/z 154, could not be identified by conventional GC/MS (gas chromatography/mass spectrometry) and library search. Such effective determination for elemental compositions of the volatile organic compounds with a unit-mass resolution quadrupole system is obviously attributed to the significant improvement of mass accuracy. More importantly, high spectral accuracy available through the instrument line-shape calibration enables highly accurate isotope pattern recognition for unknown identification.

  9. Children's preference for large portions: prevalence, determinants, and consequences.

    Science.gov (United States)

    Colapinto, Cynthia K; Fitzgerald, Angela; Taper, L Janette; Veugelers, Paul J

    2007-07-01

    Proliferation of large portions of snack and fast foods parallels dramatic increases in childhood obesity. This study investigates the prevalence, determinants, and consequences of large portions in children's diets. As part of the 2003 Children's Lifestyle and School-performance Study, we surveyed 4,966 children in Nova Scotia regarding their usual portion sizes of french fries, meats, vegetables, and potato chips using three-dimensional graduated food models. We measured heights and weights and assessed dietary intake with the Harvard Youth Adolescent Food Frequency Questionnaire. Diet quality was summarized using the Diet Quality Index International (DQI-I). Parents were surveyed on food habits and socioeconomic background. We used multilevel regression methods to examine determinants of children's large portion size choice and to evaluate the effect of this selection on energy intake, diet quality, and overweight. Children reported preference for portions of french fries, meats, and potato chips that are larger and vegetable portions that are smaller than what is recommended. Children from socioeconomically disadvantaged families or who frequently eat while watching television and in fast-food restaurants preferred larger portions of french fries and potato chips. Consequences of consuming large portions of these foods included poor diet quality and increased energy intake. Consuming large portions of vegetables was associated with lower energy intake and better diet quality. Successful marketing of large portions of french fries and potato chips may be at the expense of diet quality and appropriate energy intake. Policy regulations and nutrition education emphasizing appropriate portion sizes provide opportunities to prevent overweight and improve future health.

  10. Determination of volatiles produced during radiation processing in food and medicinal herbs; Determinacao de volateis produzidos durante o processamento por radiacao em ervas alimenticias e medicinais

    Energy Technology Data Exchange (ETDEWEB)

    Salum, Debora Christina

    2008-07-01

    In order to protect food from pathogenic microorganisms as well as to increase its shelf life while keeping sensorial properties (e.g. odor and taste), once the latter are one of the main properties required by spice buyers, it is necessary to analyze volatile formation from irradiation of medicinal and food herbs. The aim of the present study was to analyze volatile formation from Co irradiation of Laurus Cinnamomum, Piper Nigrum, Origanum Vulgare and Myristica Fragans. Possible changes on the odor of these herbs are evaluated by characterizing different radiation doses and effects on sensorial properties in order to allow better application of irradiation technology. l he samples have been irradiated in plastic packages by making use of a {sup 60}Co Gamma irradiator. Irradiation doses of 0, 5, 10, 15, 20 and 25kGy have been tested. For the analysis of the samples, SPME has been applied, while for the analysis of volatile compounds, CG/MS. Spice irradiation has promoted mostly decrease in volatile compounds when doses of 5, 10, 15, 20 and 25kGy were used. For Laurus cinnamomum, the irradiation decreased volatile by nearly 56% and 89.5% respectively, comparing to volatile from a sample which has not been previously irradiated. Differently from other spices analyzed, irradiation on Myristica Fragans has increased volatile compounds except for 4-terpineol. The miristicine (toxic substance when in large quantities, commonly mentioned as narcotic) has increased by nearly 80%. For Origanum Vulgare and Piper Nigrum, significant decrease in volatile compounds have been found, mainly when it comes to 25 kGy irradiation. In general, results indicate loss of sensorial quality of spices. (author)

  11. Simultaneous determination of six mercapturic acid metabolites of volatile organic compounds in human urine.

    Science.gov (United States)

    Ding, Yan S; Blount, Benjamin C; Valentin-Blasini, Liza; Applewhite, Heather S; Xia, Yang; Watson, Clifford H; Ashley, David L

    2009-06-01

    The widespread exposure to potentially harmful volatile organic compounds (VOCs) merits the development of practical and accurate exposure assessment methods. Measuring the urinary concentrations of VOC mercapturic acid (MA) metabolites provides noninvasive and selective information about recent exposure to certain VOCs. We developed a liquid chromatography-tandem mass spectrometry method for quantifying urinary levels of six MAs: N-acetyl-S-(2-carboxyethyl)-L-cysteine (CEMA), N-acetyl-S-(3-hydroxypropyl)-L-cysteine (HPMA), N-acetyl-S-(2-hydroxy-3-butenyl)-L-cysteine (MHBMA), N-acetyl-S-(3,4-dihydroxybutyl)-L-cysteine (DHBMA), N-acetyl-S-(2-hydroxyethyl)-L-cysteine (HEMA), and N-acetyl-S-(phenyl)-L-cysteine (PMA). The method provides good accuracy (102% mean accuracy) and high precision (3.5% mean precision). The sensitivity (limits of detection of 0.01-0.20 microg/L) and wide dynamic detection range (0.025-500 microg/L) make this method suitable for assessing VOC exposure of minimally exposed populations and those with significant exposures, such as cigarette smokers. We used this method to quantify MA levels in urine collected from smokers and nonsmokers. Median levels of creatinine-corrected CEMA, HPMA, MHBMA, DHBMA, HEMA, and PMA among nonsmokers (n = 59) were 38.1, 24.3, 21.3, 104.7, 0.9, and 0.5 microg/g creatinine, respectively. Among smokers (n = 61), median levels of CEMA, HPMA, MHBMA, DHBMA, HEMA, and PMA were 214.4, 839.7, 10.2, 509.7, 2.2, and 0.9 microg/g creatinine, respectively. All VOC MAs measured were higher among smokers than among nonsmokers, with the exception of MHBMA.

  12. Determination of volatile organic compounds from biowaste and co-fermentation biogas plants by single-sorbent adsorption.

    Science.gov (United States)

    Salazar Gómez, J I; Lohmann, H; Krassowski, J

    2016-06-01

    Characterisation of biogases is normally dedicated to the online monitoring of the major components methane and carbon dioxide and, to a lesser extent, to the determination of ammonia and hydrogen sulphide. For the case of Volatile Organic Compounds (VOCs), much less attention is usually paid, since such compounds are normally removed during gas conditioning and with exception of sulphur compounds and siloxanes represent a rather low risk to conventional downstream devices but could be a hindrance for fuel cells. However, there is very little information in the literature about the type of substances found in biogases generated from biowaste or co-fermentation plants and their concentration fluctuations. The main aim of this study was to provide information about the time dependencies of the VOCs in three biogas plants spread out through Germany from autumn until summer, which have different process control, in order to assess their potential as biofuels. Additionally, this study was an attempt to establish a correlation between the nature of the substrates used in the biogas plants and the composition of the VOCs present in the gas phase. Significant time-dependent variations in concentration were observed for most VOCs but only small changes in composition were observed. In general, terpenes and ketones appeared as the predominant VOCs in biogas. Although for substances such as esters, sulphur-organic compounds and siloxanes the average concentrations observed were rather low, they exhibited significant concentration peaks. The second biogas plant which operates with dry fermentation was found to contain the highest levels of VOCs. The amount of total volatile organic compounds (TVOCs) for the first, second and third biogas plants ranged from 35 to 259 mg Nm(-3), 291-1731 mg Nm(-3) and 84-528 mg Nm(-3), respectively.

  13. Determinants of absenteeism in a large Danish bank

    DEFF Research Database (Denmark)

    Kristensen, Kai; Juhl, Hans Jørn; Eskildsen, Jacob Kjær

    2006-01-01

    An empirical study of the determinants of absenteeism in a large Danish bank is performed. The study is based on information from approx. 7,000 employees in 500 different units. Based on a review of the absence literature a model combining the psychological and economic approaches to absence stud...... for both employees and employers play an important role for the frequency of absence. One very interesting result is that the absenteeism for employees is very clearly related to observed absence by the unit manager.......An empirical study of the determinants of absenteeism in a large Danish bank is performed. The study is based on information from approx. 7,000 employees in 500 different units. Based on a review of the absence literature a model combining the psychological and economic approaches to absence...... studies is constructed. The model is based on hedonic theory and uses the frequency metric when measuring absence. The results of the empirical study show that there is indeed a significant negative relationship between job satisfaction and absence. Furthermore, the study shows that demographic variables...

  14. Multiclass semi-volatile compounds determination in wine by gas chromatography accurate time-of-flight mass spectrometry.

    Science.gov (United States)

    Rodríguez-Cabo, T; Rodríguez, I; Ramil, M; Silva, A; Cela, R

    2016-04-15

    The performance of gas chromatography (GC) with accurate, high resolution mass spectrometry (HRMS) for the determination of a group of 39 semi-volatile compounds related to wine quality (pesticide residues, phenolic off-flavours, phenolic pollutants and bioactive stilbenes) is investigated. Solid-phase extraction (SPE) was used as extraction technique, previously to acetylation (phenolic compounds) and dispersive liquid-liquid microextraction (DLLME) concentration. Compounds were determined by GC coupled to a quadrupole time-of-flight (QTOF) MS system through an electron ionization (EI) source. The final method attained limits of quantification (LOQs) at the very low ng mL(-1) level, covering the range of expected concentrations for target compounds in red and white wines. For 38 out of 39 compounds, performance of sample preparation and determination steps were hardly affected by the wine matrix; thus, accurate recoveries were achieved by using pseudo-external calibration. Levels of target compounds in a set of 25 wine samples are reported. The capabilities of the described approach for the post-run identification of species not considered during method development, without retention time information, are illustrated and discussed with selected examples of compounds from different classes.

  15. Automated Determination of Magnitude and Source Extent of Large Earthquakes

    Science.gov (United States)

    Wang, Dun

    2017-04-01

    Rapid determination of earthquake magnitude is of importance for estimating shaking damages, and tsunami hazards. However, due to the complexity of source process, accurately estimating magnitude for great earthquakes in minutes after origin time is still a challenge. Mw is an accurate estimate for large earthquakes. However, calculating Mw requires the whole wave trains including P, S, and surface phases, which takes tens of minutes to reach stations at tele-seismic distances. To speed up the calculation, methods using W phase and body wave are developed for fast estimating earthquake sizes. Besides these methods that involve Green's Functions and inversions, there are other approaches that use empirically simulated relations to estimate earthquake magnitudes, usually for large earthquakes. The nature of simple implementation and straightforward calculation made these approaches widely applied at many institutions such as the Pacific Tsunami Warning Center, the Japan Meteorological Agency, and the USGS. Here we developed an approach that was originated from Hara [2007], estimating magnitude by considering P-wave displacement and source duration. We introduced a back-projection technique [Wang et al., 2016] instead to estimate source duration using array data from a high-sensitive seismograph network (Hi-net). The introduction of back-projection improves the method in two ways. Firstly, the source duration could be accurately determined by seismic array. Secondly, the results can be more rapidly calculated, and data derived from farther stations are not required. We purpose to develop an automated system for determining fast and reliable source information of large shallow seismic events based on real time data of a dense regional array and global data, for earthquakes that occur at distance of roughly 30°- 85° from the array center. This system can offer fast and robust estimates of magnitudes and rupture extensions of large earthquakes in 6 to 13 min (plus

  16. Determination of Total Volatile Basic Nitrogen (TVB-N) Content in Beef by Hyperspectral Imaging Technique

    OpenAIRE

    Liu Shanmei; Gan Lu

    2016-01-01

    Non-destructive determination of TVB-N content in beef using hyperspectral imaging (HSI) technique was evaluated. In order to create a robust model to predict the TVB-N content in beef, partition of sample set, spectral pretreatment, and the optimum wavelength selection were discussed. After the beef sample set was parted by concentration gradient (CG) algortithm, and the spectra of beef samples were preprocessed by standard normalized variate (SNV) combined with auto scale(AS), the partial l...

  17. Electrochemical generation of arsenic volatile species using a gold/mercury amalgam cathode. Determination of arsenic by atomic absorption spectrometry

    Directory of Open Access Journals (Sweden)

    Andrea Caiminagua

    2015-03-01

    Full Text Available The electrochemical generation of arsenic volatile species (arsine using an Au/Hg amalgam cathode in a 0.5 M H2SO4 solution, is described. Results were compared with those obtained with other cathodes commonly used for generation of arsine. The effects of the electrolytic conditions and interferent ions have been studied. Results show that the Au/Hg cathode has better tolerance to interference and higher repeatability than cathodes made out of platinum (Pt, gold (Au, reticulated glassy carbon (RGC, lead (Pb. Under optimized conditions, a 0.027 μg L−1 (3σ detection limit for As(III in aqueous solutions and a 2.4% relative standard deviation for a 0.1 μg L−1 As(III were obtained. The accuracy of the method was verified by determination of As in a certified reference material. The proposed method was applied to the determination of As in spiked tap water samples.

  18. Stable carbon isotope ratio and its use in determination of photochemical processing of ambient volatile organic compounds

    Science.gov (United States)

    Kornilova, A.; Saccon, M. S.; Rudolph, J.; Huang, L.

    2012-12-01

    Stable Carbon Isotopic Composition measurement technique can provide valuable information about trace gas processing in the atmosphere. It can not only be used to distinguish physical processes such as dilution and mixing from photochemical ageing, but also can be an important tool in identification of sources, calculating the photochemical age and qualitatively and quantitatively connecting precursors with their atmospheric products. Even though isotopic composition analysis is a valuable technique, its use is hindered by the low concentrations of compounds in the atmosphere, complexity of the samples and complex measuring instrumentation. We have developed and validated sampling and instrumental analysis techniques that can be used to perform isotopic composition measurements of volatile organic compounds (VOC) and to apply these methods to analysis of ambient samples. In this poster application of this newly developed sampling and analysis techniques will be presented and discussed using concentrations and stable carbon isotope ratios of ambient VOC collected during 2009-2010 at urban and remote locations of southern Ontario. Photochemical ages determined using conventional hydrocarbon clock will be compared to ones determined with photochemical ages derived from isotope hydrocarbon clock. Advantages of the use of stable carbon isotope ratios over other conventional methods will be outlined and applications of isotope hydrocarbon clock in air quality monitoring will be discussed.

  19. Development of a new stir bar sorptive extraction method for the determination of medium-level volatile thiols in wine.

    Science.gov (United States)

    Elpa, Decibel; Durán-Guerrero, Enrique; Castro, Remedios; Natera, Ramón; Barroso, Carmelo G

    2014-07-01

    A fast, simple, and reliable analytical method for the determination of medium-level volatile thiols in wines is presented. Stir bar sorptive extraction using ethylene glycol-silicone coated stir bars has been used in combination with thermal desorption gas chromatography with mass spectrometry for the analysis of 4-mercapto-4-methylpentan-2-one, 2-furanmethanethiol, 3-mercaptohexyl acetate, and 3-mercaptohexanol in wine. Optimization of the extraction technique was performed using a two-level fractional factorial design. For the extraction step, the optimum conditions were: Ethylene glycol and silicone coated stir bars, pH at 3.5, sample volume of 25 mL, extraction time of 90 min, NaCl content 4.0 g, and stirring speed at 500 rpm. The optimized method achieved good linearity for all studied compounds (r(2) > 0.995) and it provided detection limits of 21.52, 0.36, 0.73, and 2.55 μg/L for 4-mercapto-4-methylpentan-2-one, 2-furanmethanethiol, 3-mercaptohexyl acetate, and 3-mercaptohexanol, respectively. It was repeatable, with precisions lower than 18% relative standard deviation for both intraday and interday repeatability. The developed procedure is suitable for the determination of these kinds of compounds when they are present at medium concentration levels. It was finally applied to real wine samples with negative aroma derived from the high concentration levels of these compounds. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Determination of heat purgeable and ambient purgeable volatile organic compounds in water by gas chromatography/mass spectrometry

    Science.gov (United States)

    Rose, Donna L.; Sandstrom, Mark W.; Murtagh, Lucinda K.

    2016-09-08

    Two new analytical methods have been developed by the U.S. Geological Survey (USGS) National Water Quality Laboratory (NWQL) that allow the determination of 37 heat purgeable volatile organic compounds (VOCs) (USGS Method O-4437-16 [NWQL Laboratory Schedule (LS) 4437]) and 49 ambient purgeable VOCs (USGS Method O-4436-16 [NWQL LS 4436]) in unfiltered water. This report documents the procedures and initial performance of both methods. The compounds chosen for inclusion in the methods were determined as having high priority by the USGS National Water-Quality Assessment (NAWQA) Program. Both methods use a purge-and-trap technique with gas chromatography/mass spectrometry. The compounds are extracted from the sample by bubbling helium through a 25-milliliter sample. For the polar and less volatile compounds, the sample is heated at 60 degrees Celsius, whereas the less polar and more volatile compounds are purged using a separate analytical procedure at ambient temperature. The compounds are trapped on a sorbent trap, desorbed into a gas chromatograph/mass spectrometer for separation, and then identified and quantified. Sample preservation is recommended for both methods by adding a 1:1 solution of hydrochloric acid (HCl [1:1]) to water samples to adjust the pH to 2. Analysis within 14 days from sampling is recommended.The heat purgeable method (USGS Method O-4437-16) operates with the mass spectrometer in the simultaneous full scan/selected ion monitoring mode. This method supersedes USGS Method O-4024-03 (NWQL LS 4024). Method detection limits (MDLs) for fumigant compounds 1,2-dibromoethane, 1,2-dichloropropane, 1,2,3-trichloropropane, chloropicrin, and 1,2-dibromo-3-chloropropane range from 0.002 to 0.010 microgram per liter (µg/L). The MDLs for all remaining heat purgeable VOCs range from 0.006 µg/L for tert-butyl methyl ether to 3 µg/L for alpha-terpineol. Calculated holding times indicate that 36 of the 37 heat purgeable VOCs are stable for a minimum of 14 days

  1. The effect of surfactant on headspace single drop microextraction for the determination of some volatile aroma compounds in citronella grass and lemongrass leaves by gas chromatography

    Science.gov (United States)

    A rapid method for the determination of some volatile aromatic compounds (VACs), including citronellal, citronellol, neral, geranial, geraniol, and eugenol in citronella grass and lemongrass leaves, was developed using surfactant as a surface tension modifier while performing headspace single drop m...

  2. Aroma active volatiles in four southern highbush blueberry cultivars determined by gas chromatography-olfactometry (GC-O) and gas chromatography-mass spectrometry (GC-MS).

    Science.gov (United States)

    Du, Xiaofen; Rouseff, Russell

    2014-05-21

    Aroma active volatiles in four southern highbush blueberry cultivars ('Prima Dona', 'Jewel', 'Snow Chaser', and 'Kestrel') were determined using solid phase microextraction (SPME) in combination with gas chromatography-olfactometry (GC-O) and identified via GC-PFPD and GC-MS using retention indices of reference compounds and mass spectral data. The aromas of total, unseparated SPME extracts evaluated using GC-O were rated 8.2-9.0/10 for the four cultivars in terms of similarity to the original blueberry homogenates. In terms of GC-O aroma similarity, those aroma active volatile groups characterized as green, fruity, and floral were most intense. Of the 43 volatiles found to have aroma activity, 38 were identified and 13 had not been previously reported in blueberries. Although linalool and (E)-2-hexenal were common major aroma impact volatiles, dominant aroma-active volatiles were different for each cultivar. Principal component analysis confirmed that each cultivar possessed a unique aroma active profile as each cultivar was clustered into a separate score plot quadrant.

  3. Stock markets liberalization affects volatility?

    OpenAIRE

    Ioan Alin NISTOR; Maria-Lenuţa CIUPAC-ULICI; GHERMAN Mircea-Cristian

    2012-01-01

    Regarding the impact of liberalization, the results show that, in general, market opening is accompanied by a significant increase in market volatility. In particular, volatility tends to decrease due to large capital inflows and domestic growth.The study analyzes the impact of stock market liberalization on volatility in six emerging stock markets by using GARCH methodology. Theory on the effects of financial liberalization on volatility has been ambiguous, and empirical work has yielded con...

  4. Volatility Discovery

    DEFF Research Database (Denmark)

    Dias, Gustavo Fruet; Scherrer, Cristina; Papailias, Fotis

    The price discovery literature investigates how homogenous securities traded on different markets incorporate information into prices. We take this literature one step further and investigate how these markets contribute to stochastic volatility (volatility discovery). We formally show...... that the realized measures from homogenous securities share a fractional stochastic trend, which is a combination of the price and volatility discovery measures. Furthermore, we show that volatility discovery is associated with the way that market participants process information arrival (market sensitivity...

  5. Solid-phase microextraction-gas chromatographic determination of volatile monoaromatic hydrocarbons in soil.

    Science.gov (United States)

    Zygmunt, B; Namiesnik, J

    2001-08-01

    Benzene, toluene, ethylbenzene, three isomers of xylene, and cumene have been isolated and enriched from soil samples by a combination of water extraction at room and elevated temperature and headspace-solid-phase microextraction before their gas chromatographic-mass spectrometric (GC-MS) determination. The conditions used for all stages of sample preparation and chromatographic analysis were optimized. Analytes sampled on a polydimethylsiloxane-coated solid-phase microextraction fiber were thermally desorbed in the split/splitless injector of a gas chromatograph (GC) coupled with a mass spectrometer (MS). The desorption temperature was optimized. The GC separation was performed in a capillary column. Detection limits were found to be of the order of ca. 1 ng g(-1). Relative recoveries of the analytes from soils were found to be highly dependent on soil organic-matter content and on compound identity; they ranged from ca 92 to 96% for sandy soil (extraction at room temperature) and from ca 27 to 55% for peaty soil (extraction at elevated temperature). A few real-world soil samples were analyzed; the individual monoaromatic hydrocarbon content ranged from below detection limits to 6.4 ng g(-1) for benzene and 8.1 for the total of p- + m-xylene.

  6. Determination of Total Volatile Basic Nitrogen (TVB-N Content in Beef by Hyperspectral Imaging Technique

    Directory of Open Access Journals (Sweden)

    Liu Shanmei

    2016-01-01

    Full Text Available Non-destructive determination of TVB-N content in beef using hyperspectral imaging (HSI technique was evaluated. In order to create a robust model to predict the TVB-N content in beef, partition of sample set, spectral pretreatment, and the optimum wavelength selection were discussed. After the beef sample set was parted by concentration gradient (CG algortithm, and the spectra of beef samples were preprocessed by standard normalized variate (SNV combined with auto scale(AS, the partial least square regression (PLSR model was established using the full spectral range, which had the best prediction abilities with Rcv2 of 0.9124, Rp2 of 0.8816, RMSECV of 1.5889, and RMSEP of 1.7719, respectively. After the optimum wavelengths which is closely related to the TVB-N content of beef samples was obtained using the competitive adaptive re-weighted (CARS algorithm, a new PLSR model was established using the optimum wavelengths, which had outstanding prediction abilities with Rcv2 of 0.9235, Rp2 of 0.9241, RMSECV of 1.4881, and RMSEP of 1.4882, respectively.The study showed that HSI is a powerful technique to predict the TVB-N content in beef by a nondestructive way.

  7. Determination of gaseous semi-and low-volatile organic halogen compounds by barrier-discharge atomic emission spectrometry

    Institute of Scientific and Technical Information of China (English)

    Yifei Sun; Nobuhisa Watanabe; Wei Wang; Tianle Zhu

    2013-01-01

    A group parameter approach using "total organic halogen" is effective for monitoring gaseous organic halogen compounds,including fluorine,chlorine,and bromine compounds,generated from combustion.We described the use of barrier-discharge radiofrequencyhelium-plasma/atomic emission spectrometry,for the detection of semi-and low-volatile organic halogen compounds (SLVOXs),which can be collected by CarbotrapTM adsorbents and analyzed using thermal desorption.The optimal carrier gas flow rates at the injection and desorption lines were established to be 100 mL/min.The detection range for SLVOXs in the gaseous samples was from 10 ng to tens of micrograms.Measuring F was more diflicult than measuring Cl or Br,because the wavelength ofF is dose to that of air.The barrierdischarge radiofrequency-helium-plasma/atomic emission spectrometry measured from 85% to 103% of the SLVOXs in the gas sample.It has been found that Carbotrap B is appropriate for high-boiling-point compounds,and Carbotrap C is suitable for the determination of organic halogen compounds with lower boiling points,in the range 200-230℃.Under optimal analysis conditions,a chlorinecontaining plastic was destroyed using different oxygen concentrations.Lower oxygen concentrations resulted in the production of lower amounts of organic halogen compounds.

  8. Polymeric ionic liquid coatings versus commercial solid-phase microextraction coatings for the determination of volatile compounds in cheeses.

    Science.gov (United States)

    Trujillo-Rodríguez, María J; Yu, Honglian; Cole, William T S; Ho, Tien D; Pino, Verónica; Anderson, Jared L; Afonso, Ana M

    2014-04-01

    The extraction performance of four polymeric ionic liquid (PIL)-based solid-phase microextraction (SPME) coatings has been studied and compared to that of commercial SPME coatings for the extraction of 16 volatile compounds in cheeses. The analytes include 2 free fatty acids, 2 aldehydes, 2 ketones and 10 phenols and were determined by headspace (HS)-SPME coupled to gas chromatography (GC) with flame-ionization detection (FID). The PIL-based coatings produced by UV co-polymerization were more efficient than PIL-based coatings produced by thermal AIBN polymerization. Partition coefficients of analytes between the sample and the coating (Kfs) were estimated for all PIL-based coatings and the commercial SPME fiber showing the best performance among the commercial fibers tested: carboxen-polydimethylsyloxane (CAR-PDMS). For the PIL-based fibers, the highest K(fs) value (1.96 ± 0.03) was obtained for eugenol. The normalized calibration slope, which takes into account the SPME coating thickness, was also used as a simpler approximate tool to compare the nature of the coating within the determinations, with results entirely comparable to those obtained with estimated K(fs) values. The PIL-based materials obtained by UV co-polymerization containing the 1-vinyl-3-hexylimidazolium chloride IL monomer and 1,12-di(3-vinylimiazolium)dodecane dibromide IL crosslinker exhibited the best performance in the extraction of the select analytes from cheeses. Despite a coating thickness of only 7 µm, this copolymeric sorbent coating was capable of quantitating analytes in HS-SPME in a 30 to 2000 µg L(-1) concentration range, with correlation coefficient (R) values higher than 0.9938, inter-day precision values (as relative standard deviation in %) varying from 6.1 to 20%, and detection limits down to 1.6 µg L(-1).

  9. Latent Integrated Stochastic Volatility, Realized Volatility, and Implied Volatility: A State Space Approach

    DEFF Research Database (Denmark)

    Bach, Christian; Christensen, Bent Jesper

    We include simultaneously both realized volatility measures based on high-frequency asset returns and implied volatilities backed out of individual traded at the money option prices in a state space approach to the analysis of true underlying volatility. We model integrated volatility as a latent...... fi…rst order Markov process and show that our model is closely related to the CEV and Barndorff-Nielsen & Shephard (2001) models for local volatility. We show that if measurement noise in the observable volatility proxies is not accounted for, then the estimated autoregressive parameter in the latent...... process is downward biased. Implied volatility performs better than any of the alternative realized measures when forecasting future integrated volatility. The results are largely similar across the stock market (S&P 500), bond market (30-year U.S. T-bond), and foreign currency exchange market ($/£ )....

  10. Conductometric titration to determine total volatile basic nitrogen (TVB-N) for post-mortem interval (PMI).

    Science.gov (United States)

    Xia, Zhiyuan; Zhai, Xiandun; Liu, Beibei; Mo, Yaonan

    2016-11-01

    Precise measurement of cadaver decomposition rate is the basis to accurate post-mortem interval (PMI) estimation. There are many approaches explored in recent years, however, it is still unsolved completely. Total volatile basic nitrogen (TVB-N), which is an important index to predict meat freshness and shelf life in food science, could serve as an indicator for measuring PMI associated decomposition rate of cadavers. The aim of this work was to establish a practical method to determine TVB-N in cadaver soft tissues (mainly skeletal muscle) for measuring decomposition rate. Determination of TVB-N in the simulation and animal experiments was conducted by steam distillation and conductometric titration using Kjeldahl distillation unit and conductivity meter. In simulation, standard concentrations of ammonium were used as TVB analogies, TVB-N contents were determined and the recovery rates of nitrogen were calculated. In animal experiment, TVB-N in skeletal muscle of forty-two rats was determined at different PMIs for 312 h at 24 °C ± 1 °C. The relationship between PMI and TVB-N was investigated also. The method showed high precision with 99%-100% recovery rates. TVB-N in skeletal muscle changed significantly with PMI especially after 24 h, and the data fit well to y = 3.35 E(-5)x(3)-2.17 E(-2)x(2)+6.13x-85.82 (adj. R(2) = 0.985). ECi (initial electrical conductivity in the samples just before titration) had positive linear relationship to final measured TVB-N values, y = 1.98x+16.16 (adj. R(2) = 0.985). The overall results demonstrated that the method is accurate, rapid and flexible, which could be expected as a basic technique for measuring decomposition rate in later PMI-estimation researches. Further studies are needed to validate our findings. Copyright © 2016 Elsevier Ltd and Faculty of Forensic and Legal Medicine. All rights reserved.

  11. Effect of management (organic vs conventional) on volatile profiles of six plum cultivars (Prunus salicina Lindl.). A chemometric approach for varietal classification and determination of potential markers.

    Science.gov (United States)

    Cuevas, F J; Moreno-Rojas, J M; Arroyo, F; Daza, A; Ruiz-Moreno, M J

    2016-05-15

    The volatile profiles of six plum cultivars ('Laetitia', 'Primetime', 'Sapphire', 'Showtime', 'Songold' and 'Souvenir') produced under two management systems (conventional and organic) and harvested in two consecutive years were obtained by HS-SPME-GC-MS. Twenty-five metabolites were determined, five of which (pentanal, (E)-2-heptenal, 1-octanol, eucalyptol and 2-pentylfuran) are reported for the first time in Prunus salicina Lindl. Hexanal stood out as a major volatile compound affected by the management system. In addition, partial least square discriminant analysis (PLS-DA) achieved an effective classification of genotypes based on their volatile profiles. A high classification accuracy model was obtained with a sensitivity of 97.9% and a specificity of 99.6%. Furthermore, the application of a dual criterion, based on a method of variable selection, VIP (variable importance in projection) and the results of a univariate analysis (ANOVA), allowed the identification of potential volatile markers in 'Primetime', 'Showtime' and 'Souvenir' genotypes (cultivars not characterised to date).

  12. Idiosyncratic Volatility Puzzle

    DEFF Research Database (Denmark)

    Aslanidis, Nektarios; Christiansen, Charlotte; Lambertides, Neophytos;

    from a large pool of macroeconomic and Önancial variables. Cleaning for macro-Önance e§ects reverses the puzzling negative relation between returns and idiosyncratic volatility documented previously. Portfolio analysis shows that the e§ects from macro-Önance factors are economically strong......In this paper, we scrutinize the cross-sectional relation between idiosyncratic volatility and stock returns. As a novelty, the idiosyncratic volatility is obtained by conditioning upon macro-Önance factors as well as upon traditional asset pricing factors. The macro-Önance factors are constructed...

  13. Virtual volatility

    Science.gov (United States)

    Silva, A. Christian; Prange, Richard E.

    2007-03-01

    We introduce the concept of virtual volatility. This simple but new measure shows how to quantify the uncertainty in the forecast of the drift component of a random walk. The virtual volatility also is a useful tool in understanding the stochastic process for a given portfolio. In particular, and as an example, we were able to identify mean reversion effect in our portfolio. Finally, we briefly discuss the potential practical effect of the virtual volatility on an investor asset allocation strategy.

  14. Virtual volatility

    OpenAIRE

    A. Christian Silva; Prange, Richard E.

    2006-01-01

    We introduce the concept of virtual volatility. This simple but new measure shows how to quantify the uncertainty in the forecast of the drift component of a random walk. The virtual volatility also is a useful tool in understanding the stochastic process for a given portfolio. In particular, and as an example, we were able to identify mean reversion effect in our portfolio. Finally, we briefly discuss the potential practical effect of the virtual volatility on an investor asset allocation st...

  15. Plant volatiles.

    Science.gov (United States)

    Baldwin, Ian T

    2010-05-11

    Plant volatiles are the metabolites that plants release into the air. The quantities released are not trivial. Almost one-fifth of the atmospheric CO2 fixed by land plants is released back into the air each day as volatiles. Plants are champion synthetic chemists; they take advantage of their anabolic prowess to produce volatiles, which they use to protect themselves against biotic and abiotic stresses and to provide information - and potentially disinformation - to mutualists and competitors alike. As transferors of information, volatiles have provided plants with solutions to the challenges associated with being rooted in the ground and immobile.

  16. Feasibility of halogen determination in noncombustible inorganic matrices by ion chromatography after a novel volatilization method using microwave-induced combustion.

    Science.gov (United States)

    Pereira, Rodrigo M; Costa, Vanize C; Hartwig, Carla A; Picoloto, Rochele S; Flores, Erico M M; Duarte, Fabio A; Mesko, Marcia F

    2016-01-15

    A microwave-induced combustion (MIC) system based on the volatilization process was applied for subsequent halogen determination from noncombustible inorganic matrices. Portland cement samples were selected to demonstrate the feasibility of the proposed method, allowing the subsequent determination of Cl and F by ion chromatography (IC). Samples were mixed with high-purity microcrystalline cellulose, wrapped with a polyethylene film and combusted in quartz closed vessels pressurized with oxygen (20bar). Water and NH4OH (10, 25 or 50m mol L(-1)) were evaluated for Cl and F absorption, but water was selected, using 5min of reflux after volatilization. Final solutions were also suitable for analysis by pontentiometry with ion-selective electrode (ISE) for both analytes, and no difference was found when comparing the results with IC. The accuracy of the proposed method for Cl was evaluated by analysis of certified reference materials (CRMs), and agreement with certified values ranged from 98% to 103%. Results were also compared to those using the procedure recommended by the American Society of Testing and Materials (ASTM) for the determination of total chlorides (C114-13), and no difference was found. Volatilization by MIC using a mixture of cement, cellulose and a biological CRM was carried out in order to evaluate the accuracy for F, and recovery was about 96%. The proposed method allowed suitable limits of detection for Cl and F by IC (99 and 18mg kg(-1), respectively) for routine analysis of cement. Using the proposed method, a relatively low standard deviation (method, were obtained. Therefore, the method for volatilization of Cl and F by MIC and subsequent determination by IC can be proposed as a suitable alternative for cement analysis.

  17. Comportamento e estrutura a termo da volatilidade de empresas de grande e pequeno porte Behavior and term structure of volatility for large and small companies

    Directory of Open Access Journals (Sweden)

    Pablo Rogers

    2008-01-01

    Full Text Available Em contraposição às hipóteses para sustentação dos modelos financeiros "clássicos", como o Capital Asset Pricing Model (CAPM de Sharpe-Litner-Mossin, a literatura recente de Finanças tem documentado que algumas características das empresas se mostram relevantes para explicar retornos esperados. Este artigo tem por objetivo analisar se o tamanho da empresa no Brasil é uma característica importante para explicar uma outra dimensão da relação risco versus retorno: a volatilidade. Como metodologia, procedeu-se a uma reestruturação completa do índice IBrX da Bolsa de Valores de São Paulo (Bovespa, obtendo-se dois novos índices: um de empresas com grande porte e outro de empresas com pequeno porte. A partir dos índices construídos, analisaram-se o comportamento e a estrutura a termo da volatilidade, com ajustes dos modelos GARCH (1,1 e TARCH (1,1. Em linhas gerais, pode-se concluir que o comportamento e a estrutura a termo da volatilidade de empresas de grande e pequeno porte são diferentes, o que permite a incorporação da característica tamanho da empresa nas funções financeiras, tais como decisões de investimentos, precificação de títulos e gerenciamento de risco.Recent finance literature states that certain company characteristics are relevant to explain the returns expected, which is contrary to classic financial models such as the Capital Asset Pricing Model. The effect of company size in Brazil was investigated to verify if it explains another aspect of the relationship of risk versus return, which is volatility. The method used was to restructure the IBrX index (Sao Paulo Stock Exchange - Bovespa to obtain a new index for large sized companies and also another for small companies. The behavior and term structure of volatility was analyzed using adjustments of the GARCH (1.1 and TARCH (1.1 models for each of the two new indices. It was concluded that, in general, small and large companies have different behaviors

  18. Use of Nitrogen Isotope To Determine Fertilizer- and Soil-Derived Ammonia Volatilization in a Rice/Wheat Rotation System.

    Science.gov (United States)

    Zhao, Xu; Yan, Xiaoyuan; Xie, Yingxin; Wang, Shenqiang; Xing, Guangxi; Zhu, Zhaoliang

    2016-04-20

    The nitrogen (N) isotope method reveals that application of fertilizer N can increase crop uptake or denitrification and leaching losses of native soil N via the "added N interaction". However, there is currently little evidence of the impact of added N on soil N losses through NH3 volatilization using (15)N methodologies. In the present study, a three-year rice/wheat rotated experiment with 30% (15)N-labeled urea applied in the first rice season and unlabeled urea added in the following five crop seasons was performed to investigate volatilization of NH3 from fertilizer and soil N. We found 9.28% of NH3 loss from (15)N urea and 2.88-7.70% declines in (15)N-NH3 abundance occurred during the first rice season, whereas 0.11% of NH3 loss from (15)N urea and 0.02-0.21% enrichments in (15)N-NH3 abundance happened in the subsequent seasons. The contributions of fertilizer- and soil-derived N to NH3 volatilization from a rice/wheat rotation were 75.8-88.4 and 11.6-24.2%, respectively. These distinct variations in (15)N-NH3 and substantial soil-derived NH3 suggest that added N clearly interacts with the soil source contributing to NH3 volatilization.

  19. Tetraglyme Trap for the Determination of Volatile Organic Compounds in Urban Air: Projects for Undergraduate Analytical Chemistry

    Science.gov (United States)

    Hope, Wilbert W.; Johnson, Clyde; Johnson, Leon P.

    2004-01-01

    The differences in the levels of volatile organic compounds (VOCs), in the ambient air from the two urban locations, were studied by the undergraduate analytical chemistry students. Tetraglyme is very widely used due to its simplicity and its potential for use to investigate VOCs in ambient and indoor air employing a purge-and-trap concentrator…

  20. A fast and simple method for quantitative determination of fat-derived medium and low-volatile compounds in cheese

    NARCIS (Netherlands)

    Alewijn, M.; Sliwinski, E.L.; Wouters, J.T.M.

    2003-01-01

    Cheese flavour is a mixture of many (volatile) compounds, mostly formed during ripening. The current method was developed to qualify and quantify fat-derived compounds in cheese. Cheese samples were extracted with acetonitrile, which led to a concentrated solution of potential favour compounds, main

  1. Unstable volatility

    DEFF Research Database (Denmark)

    Casas, Isabel; Gijbels, Irène

    2012-01-01

    The objective of this paper is to introduce the break-preserving local linear (BPLL) estimator for the estimation of unstable volatility functions for independent and asymptotically independent processes. Breaks in the structure of the conditional mean and/or the volatility functions are common i...

  2. Unstable volatility

    DEFF Research Database (Denmark)

    Casas, Isabel; Gijbels, Irène

    2012-01-01

    The objective of this paper is to introduce the break-preserving local linear (BPLL) estimator for the estimation of unstable volatility functions for independent and asymptotically independent processes. Breaks in the structure of the conditional mean and/or the volatility functions are common i...

  3. TECHNICAL JUSTIFICATION FOR CHOOSING PROPANE AS A CALIBRATION AGENT FOR TOTAL FLAMMABLE VOLATILE ORGANIC COMPOUND (VOC) DETERMINATIONS

    Energy Technology Data Exchange (ETDEWEB)

    DOUGLAS, J.G.

    2006-07-06

    This document presents the technical justification for choosing and using propane as a calibration standard for estimating total flammable volatile organic compounds (VOCs) in an air matrix. A propane-in-nitrogen standard was selected based on a number of criteria: (1) has an analytical response similar to the VOCs of interest, (2) can be made with known accuracy and traceability, (3) is available with good purity, (4) has a matrix similar to the sample matrix, (5) is stable during storage and use, (6) is relatively non-hazardous, and (7) is a recognized standard for similar analytical applications. The Waste Retrieval Project (WRP) desires a fast, reliable, and inexpensive method for screening the flammable VOC content in the vapor-phase headspace of waste containers. Table 1 lists the flammable VOCs of interest to the WRP. The current method used to determine the VOC content of a container is to sample the container's headspace and submit the sample for gas chromatography--mass spectrometry (GC-MS) analysis. The driver for the VOC measurement requirement is safety: potentially flammable atmospheres in the waste containers must be allowed to diffuse prior to processing the container. The proposed flammable VOC screening method is to inject an aliquot of the headspace sample into an argon-doped pulsed-discharge helium ionization detector (Ar-PDHID) contained within a gas chromatograph. No actual chromatography is performed; the sample is transferred directly from a sample loop to the detector through a short, inert transfer line. The peak area resulting from the injected sample is proportional to the flammable VOC content of the sample. However, because the Ar-PDHID has different response factors for different flammable VOCs, a fundamental assumption must be made that the agent used to calibrate the detector is representative of the flammable VOCs of interest that may be in the headspace samples. At worst, we desire that calibration with the selected

  4. Volatile organic compounds in whole blood - determination by heated dynamic headspace purge and trap isotope-dilution GC/MS. Special report, November 1984-August 1987

    Energy Technology Data Exchange (ETDEWEB)

    Cramer, P.H.; Boggess, K.E.; Hosenfeld, J.M.

    1987-07-01

    The method described was developed for the determination of a selected list of 30 organic compounds in whole human blood. The method is a heated dynamic head-space purge and trap gas chromatographic method using mass spectrometry in the limited mass-scan mode. A whole blood sample is diluted with organic free water and the mixture fortified with isotopically labeled compounds. The mixture is subsequently heated to 50/sup 0/C while stirred, and the volatile components are purged from the mixture and collected on an adsorbent trap. The volatile compounds are thermally desorbed from the trap onto a wide-bore fused-silica capillary column. Detection of the compounds is accomplished using mass spectrometry in the limited mass-scan mode where only selected ions are scanned. Quantitation of the analytes is accomplished by using the specific ion responses from standards of the analytes and their corresponding labeled analogs or internal standards.

  5. Volatile composition in raspberry cultivars grown in the Pacific Northwest determined by stir bar sorptive extraction-gas chromatography-mass spectrometry.

    Science.gov (United States)

    Malowicki, Sarah M M; Martin, Robert; Qian, Michael C

    2008-06-11

    Twenty-nine volatile compounds in 'Chilliwack', 'Tulameen', 'Willamette', 'Yellow Meeker', and 'Meeker' raspberries were quantified using stir bar sorptive extraction (SBSE) paired with gas chromatography-mass spectrometry (GC-MS). Good correlation coefficients were obtained with most aroma-active compounds in raspberry, with quantification limits of 1 microg/kg. However, poor recoveries were observed for raspberry ketone and zingerone. Quantitative data showed that volatile concentrations varied for different cultivars. Large variations for alpha-ionone, beta-ionone, geraniol, linalool, and ( Z)-3-hexenol were observed in different raspberry cultivars. In addition, the volatile compositions in 'Meeker' raspberry grown at different locations also varied. The chiral isomeric ratios of raspberry ketone, alpha-ionone, alpha-pinene, linalool, terpinen-4-ol, delta-octalactone, delta-decalactone, and 6-methyl-5-hepten-2-ol were studied using a CyclosilB column. alpha-Ionone, alpha-pinene, delta-octalactone, and delta-decalactone had strong chiral isomeric preference, with more than 96% for one isomeric form. Much weaker chiral isomeric preference was observed for terpinen-4-ol, while linalool was almost a racemic mixture. Both growing locations and cultivars affect the isomeric ratio of linalool with a range of 37-51% for ( R)-linalool.

  6. Determination of the volatile composition in brown millet, milled millet and millet bran by gas chromatography/mass spectrometry.

    Science.gov (United States)

    Liu, Jingke; Tang, Xia; Zhang, Yuzong; Zhao, Wei

    2012-02-24

    The volatile compounds from brown millet (BM), milled millet (MM) and millet bran (MB) were extracted using simultaneous distillation/extraction with a Likens-Nickerson apparatus. The extracts were analysed using gas chromatography coupled with mass spectrometry (GC-MS). A total of 65 volatile compounds were identified in all of the samples. Among these compounds, 51, 51 and 49 belonged to BM, MM and MB, respectively. Aldehydes and benzene derivatives were the most numerous among all of the compounds. Three compounds (hexanal, hexadecanoic acid and 2-methylnaphthalene) were dominant in the BM and MM materials. Eight compounds (hexanal, nonanal, (E)-2-nonenal, naphthalene, 2-methylnaphthalene, 1-methylnaphthalene, hexadecanoic acid and 2-pentylfuran) were dominant in the MB materials. Apart from the aromatic molecules, which were present in all fractions, compounds present only in BM, MM or MB were also identified.

  7. Magma storage before large and small explosive eruption at Grímsvötn volcano, Iceland, constrained by thermobarometry and volatiles in melt inclusions

    Science.gov (United States)

    Haddadi, Baptiste; Sigmarsson, Olgeir; Larsen, Gudrun

    2017-04-01

    Basaltic eruptions at Grímsvötn occur every decade on average. These are normally phreatomagmatic of a low intensity whereas occasionally larger eruptions with an initial plinian phase take place. The last eruption in May 2011 reached into the stratosphere with heavy ash fall over south Iceland. What causes the difference in eruption intensity at Grímsvötn is not understood. In order to discuss this difference, the crystallization conditions of the eruptive magma were determined through thermobarometry and volatile concentration measured on melt inclusion (MI) and groundmass glasses. Tephra of the two largest historical eruptions (2011 and 1873) and two small eruptions (2004 and 1823) were investigated. Pressure and temperature estimates of crystallization are obtained through equilibrium clinopyroxene-glass (cpx-liq) pairs, where both adjacent groundmass glass and that of melt inclusions (MI) were measured. Most cpx-liq equilibria give pressure of 4 ±1 kbar corresponding to approximately 15 km depth. The cpx crystallization occurred over a considerable temperature range, 1065-1175 °C that correlates with the estimated pressure in products of the 19th century eruptions. Sulfur and chlorine concentrations are highest in MI of the larger eruptions (1974-1789 ppm and 339-266 ppm, respectively) together with lowest groundmass glass concentrations (908-766 ppm and 208-180 ppm, respectively). Quenching with glacial water explains higher groundmass values for the smaller phreatomagmatic eruptions. The differences in volatile concentrations between MI and groundmass glass (S) and the average sulfur concentration in the degassed groundmass correlate with known eruptive volume for the 21st century eruptions and that of the Laki eruption. This suggests water/magma ratio control of S degassing efficiency and allows crude estimates of unknown volumes for older eruptions. The higher volatile concentrations of MI in the larger eruptions are likely to reflect recharge of

  8. Composition of Sulla (Hedysarum coronarium L. Honey Solvent Extractives Determined by GC/MS: Norisoprenoids and Other Volatile Organic Compounds

    Directory of Open Access Journals (Sweden)

    Dragan Bubalo

    2010-09-01

    Full Text Available Samples of unifloral sulla (Hedysarum coronarum L. honey from Sardinia (Italy were analysed. To investigate the chemical composition of the honey volatiles two solvent systems were used for ultrasonic solvent extraction (USE: 1 a 1:2 (v/v pentane and diethyl ether mixture and 2 dichloromethane. All the extracts were analysed by GC and GC/MS. These procedures have permitted the identification of 56 compounds that include norisoprenoids, benzene derivatives, aliphatic compounds and Maillard reaction products. Norisoprenoids were the major compounds in both extracts, dominated by vomifoliol (5.3-11.2%; 9.6-14.0% followed by minor percentages of other norisoprenoids such as α-isophorone, 4-ketoisophorone, 3-oxo-α-ionol or 3-oxo-α-ionone. Other abundant single compounds in the extracts were 3-hydroxy-4-phenylbutan-2-one (0.8-5.4%; 0.6-5.7% and methyl syringate (3.0-5.7%; 2.2-4.1%. The composition of the volatiles and semi-volatiles in the obtained extracts suggests that sulla honey is quite distinctive relative to the other honeys that have been chemically studied by GC/MS, but no specific markers of the honey botanical origin were found.

  9. Composition of sulla (Hedysarum coronarium L.) honey solvent extractives determined by GC/MS: norisoprenoids and other volatile organic compounds.

    Science.gov (United States)

    Jerković, Igor; Tuberoso, Carlo I G; Tuberso, Carlo I G; Gugić, Mirko; Bubalo, Dragan

    2010-09-09

    Samples of unifloral sulla (Hedysarum coronarum L.) honey from Sardinia (Italy) were analysed. To investigate the chemical composition of the honey volatiles two solvent systems were used for ultrasonic solvent extraction (USE): 1) a 1:2 (v/v) pentane and diethyl ether mixture and 2) dichloromethane. All the extracts were analysed by GC and GC/MS. These procedures have permitted the identification of 56 compounds that include norisoprenoids, benzene derivatives, aliphatic compounds and Maillard reaction products. Norisoprenoids were the major compounds in both extracts, dominated by vomifoliol (5.3-11.2%; 9.6-14.0%) followed by minor percentages of other norisoprenoids such as α-isophorone, 4-ketoisophorone, 3-oxo-α-ionol or 3-oxo-α-ionone. Other abundant single compounds in the extracts were 3-hydroxy-4-phenylbutan-2-one (0.8-5.4%; 0.6-5.7%) and methyl syringate (3.0-5.7%; 2.2-4.1%). The composition of the volatiles and semi-volatiles in the obtained extracts suggests that sulla honey is quite distinctive relative to the other honeys that have been chemically studied by GC/MS, but no specific markers of the honey botanical origin were found.

  10. Recent Advances in Volatiles of Teas

    Directory of Open Access Journals (Sweden)

    Xin-Qiang Zheng

    2016-03-01

    Full Text Available Volatile compounds are important components of tea aroma, a key attribute of sensory quality. The present review examines the formation of aromatic volatiles of various kinds of teas and factors influencing the formation of tea volatiles, including tea cultivar, growing environment and agronomic practices, processing method and storage of tea. The determination of tea volatiles and the relationship of active-aroma volatiles with the sensory qualities of tea are also discussed in the present paper.

  11. Simultaneous determination of five mercapturic acid derived from volatile organic compounds in human urine by LC-MS/MS and its application to relationship study.

    Science.gov (United States)

    Zhang, Xiaotao; Xiong, Wei; Shi, Longkai; Hou, Hongwei; Hu, Qingyuan

    2014-09-15

    Acrylonitrile, acrolein, 1,3-butadiene, benzene, and crotonaldehyde are hazard volatile organic compounds in tobacco smoke, which can be metabolized to mercapturic acids (MAs) excreted in urine. MAs are can be regarded as important and specific biomarkers to evaluate exposure to those carcinogenic volatile organic compounds. A simultaneous determination of N-acetyl-S-2-cyanoethyl-cysteine (CEMA), 3-hydroxypropyl)-L-cysteine (3-HPMA), N-acetyl-S-(3,4-dihydroxybutyl)-L-cysteine (DHBMA), N-acetyl-S-(phenyl)-L-cysteine (SPMA) and 3-hydroxy-1-methylpropylmercapturic acid (HMPMA) derived from five volatile organic compounds by column-switching LC-MS/MS has been described. MAs were concentrated and cleaned up by an online reusable pre-column packed with restricted access material. The intra- and inter-day precisions of the method ranged from 0.7% to 15.2%. The LODs was 0.013-0.053 ng/mL. The recovery of the whole analytical procedure ranged from 79.3% to 116%. After validation, this method was successfully applied to urine samples from smokers (n=246) and nonsmokers (n=58). The results showed MAs in urine from smokers were significantly higher than that in nonsmoker except for SPMA. Urinary CEMA significantly correlated with 3-HPMA (r=0.763, PCEMA, 3-HPMA and HMPMA are potential biomarkers to distinguish the differences between smokers and nonsmokers.

  12. DETERMIN LARGE PRIME NUMBERS TO COMPUTE RSA SYSTEM PARAMETERS

    Directory of Open Access Journals (Sweden)

    Ioan Mang

    2008-05-01

    Full Text Available Cryptography, the secret writing, is probably same old as writing itself and has applications in data security insurance. There are cryptosystems where the encipher algorithm can be public. These are public key algorithms. Research on public key algorithms has been concerned with security aspects. The results of this research have induced sufficient confidence to apply public key cryptography a larger scale. The most used and checked public key-based cryptosystem was find by Rivest, Shamir and Adleman, so called RSA system. This paper shows the RSA algorithm. We have realised a program that is able to determine prime numbers with over 100 digits and compute RSA system parameters.

  13. Evaluation of Volatile Organic Compounds and Carbonyl Compounds Present in the Cabins of Newly Produced, Medium- and Large-Size Coaches in China

    Directory of Open Access Journals (Sweden)

    Yan-Yang Lu

    2016-06-01

    Full Text Available An air-conditioned coach is an important form of transportation in modern motorized society; as a result, there is an increasing concern of in-vehicle air pollution. In this study, we aimed to identify and quantify the levels of volatile organic compounds (VOCs and carbonyl compounds (CCs in air samples collected from the cabins of newly produced, medium- and large-size coaches. Among the identified VOCs and CCs, toluene, ethylbenzene, xylene, formaldehyde, acetaldehyde, acrolein/acetone, and isovaleraldehyde were relatively abundant in the cabins. Time was found to affect the emissions of the contaminants in the coaches. Except for benzaldehyde, valeraldehyde and benzene, the highest in-vehicle concentrations of VOCs and CCs were observed on the 15th day after coming off the assembly line, and the concentrations exhibited an approximately inverted U-shaped pattern as a function of time. Interestingly, this study also showed that the interior temperature of the coaches significantly affected the VOCs emissions from the interior materials, whereas the levels of CCs were mainly influenced by the relative humidity within the coaches. In China, guidelines and regulations for the in-vehicle air quality assessment of the coaches have not yet been issued. The results of this study provide further understanding of the in-vehicle air quality of air-conditioned coaches and can be used in the development of both specific and general rules regarding medium- and large-size coaches.

  14. Evaluation of Volatile Organic Compounds and Carbonyl Compounds Present in the Cabins of Newly Produced, Medium- and Large-Size Coaches in China

    Science.gov (United States)

    Lu, Yan-Yang; Lin, Yi; Zhang, Han; Ding, Dongxiao; Sun, Xia; Huang, Qiansheng; Lin, Lifeng; Chen, Ya-Jie; Chi, Yu-Lang; Dong, Sijun

    2016-01-01

    An air-conditioned coach is an important form of transportation in modern motorized society; as a result, there is an increasing concern of in-vehicle air pollution. In this study, we aimed to identify and quantify the levels of volatile organic compounds (VOCs) and carbonyl compounds (CCs) in air samples collected from the cabins of newly produced, medium- and large-size coaches. Among the identified VOCs and CCs, toluene, ethylbenzene, xylene, formaldehyde, acetaldehyde, acrolein/acetone, and isovaleraldehyde were relatively abundant in the cabins. Time was found to affect the emissions of the contaminants in the coaches. Except for benzaldehyde, valeraldehyde and benzene, the highest in-vehicle concentrations of VOCs and CCs were observed on the 15th day after coming off the assembly line, and the concentrations exhibited an approximately inverted U-shaped pattern as a function of time. Interestingly, this study also showed that the interior temperature of the coaches significantly affected the VOCs emissions from the interior materials, whereas the levels of CCs were mainly influenced by the relative humidity within the coaches. In China, guidelines and regulations for the in-vehicle air quality assessment of the coaches have not yet been issued. The results of this study provide further understanding of the in-vehicle air quality of air-conditioned coaches and can be used in the development of both specific and general rules regarding medium- and large-size coaches. PMID:27314375

  15. Volatility Risk

    OpenAIRE

    Zhiguang Wang

    2009-01-01

    Classical capital asset pricing theory tells us that riskaverse investors would require higher returns to compensate for higher risk on an investment. One type of risk is price (return) risk, which reflects uncertainty in the price level and is measured by the volatility (standard deviation) of asset returns. Volatility itself is also known to be random and hence is perceived as another type of risk. Investors can bear price risk in exchange for a higher return. But are investors willing to p...

  16. Proton transfer reaction-mass spectrometry: online and rapid determination of volatile organic compounds of microbial origin.

    Science.gov (United States)

    Romano, Andrea; Capozzi, Vittorio; Spano, Giuseppe; Biasioli, Franco

    2015-05-01

    Analytical tools for the identification and quantification of volatile organic compounds (VOCs) produced by microbial cultures have countless applications in an industrial and research context which are still not fully exploited. The various techniques for VOC analysis generally arise from the application of different scientific and technological philosophies, favoring either sample throughput or chemical information. Proton transfer reaction-mass spectrometry (PTR-MS) represents a valid compromise between the two aforementioned approaches, providing rapid and direct measurements along with highly informative analytical output. The present paper reviews the main applications of PTR-MS in the microbiological field, comprising food, environmental, and medical applications.

  17. Determination of volatile concentrations in fluorapatite of Martian shergottite NWA 2975 by combining synchrotron FTIR, Raman spectroscopy, EMPA, and TEM, and inferences on the volatile budget of the apatite host-magma

    Science.gov (United States)

    SłAby, Ewa; Koch-Müller, Monika; FöRster, Hans-Jürgen; Wirth, Richard; Rhede, Dieter; Schreiber, Anja; Schade, Ulrich

    2016-02-01

    We combined the focused ion beam sample preparation technique with polarized synchrotron-based FTIR (Fourier transform infrared) spectroscopy, laser-Raman spectroscopy, electron microprobe analysis (EMPA), and transmission electron microscope (TEM) analysis to identify and quantify structurally bound OH, F, Cl, and CO3 groups in fluorapatite from the Northwest Africa 2975 (NWA 2975) shergottite. In this study, the first FTIR spectra of the OH-stretching region from a Martian apatite are presented that show characteristic OH-bands of a F-rich, hydroxyl-bearing apatite. Depending on the method of apatite-formula calculation and whether charge balance is assumed or not, the FTIR-based quantification of the incorporated OH, expressed as wt% H2O, is in variably good agreement with the H2O concentration calculated from electron microprobe data. EMP analyses yielded between 0.35 and 0.54 wt% H2O, and IR data yielded an average H2O content of 0.31 ± 0.03 wt%, consistent with the lower range determined from EMP analyses. The TEM observations implied that the volatiles budget of fluorapatite is magmatic. The water content and the relative volatile ratios calculated for the NWA 2975 magma are similar to those established for other enriched or intermediate shergottites. It is difficult to define the source of enrichment: either Martian wet mantle or crustal assimilation. Comparing the environment of parental magma generation for NWA 2975 with the terrestrial mantle in terms of water content, it displays a composition intermediate between enriched and depleted MORB.

  18. Determination of volatile compounds in Magnolia bark by microwave-assisted extraction coupled to headspace solid-phase microextraction and gas chromatography-mass spectrometry.

    Science.gov (United States)

    Sha, Yun F; Huang, Tao M; Shen, Shun; Duan, Geng L

    2004-05-01

    A method is described for the determination of volatile compounds in Magnolia bark using microwave-assisted extraction coupled to headspace solid-phase microextraction (MAE-HS-SPME), followed by gas chromatography with mass spectrometry (GC-MS). Parameters affecting the extraction efficiency, such as sampling time and temperature, microwave irradiation power and desorption time, were investigated to achieve the optimal conditions. The result obtained was compared with that of steam distillation; only small differences existed between these two methods. Therefore, the proposed method seems to be a feasible and relatively simple, fast and solvent-free procedure for identification of essential oils in Magnolia bark.

  19. Anodized aluminum wire as a solid-phase microextraction fiber for rapid determination of volatile constituents in medicinal plant.

    Science.gov (United States)

    Gholivand, Mohammad Bagher; Piryaei, Marzieh; Abolghasemi, Mir Mahdi

    2011-09-02

    Headspace solid phase microextraction using anodized aluminum fiber in combination with capillary GC-MS was utilized as monitoring technique for the collection and detection of the volatile compounds of Echinophora platyloba DC. Experimental parameters, including the sample weight, extraction temperature, extraction time and humidity effect, desorption time and desorption temperature were examined and optimized. Using HS-SPME followed by GC-MS, 53 compounds were separated and identified in E. platyloba DC, which mainly included E-β ocimene (47.63%), R-D-decalactone (13.28%), α-pinene (7.43%) and nonane (6.71%). Compared with hydrodistillation (HD), HS-SPME, provides the advantages of a small amount of sample, timesaving, simplicity and cheapness. To the best of our knowledge, this is the first report on using anodized aluminum fiber in solid-phase microextraction coupled to headspace for the investigation of volatile fraction of medicinal plant. Copyright © 2011 Elsevier B.V. All rights reserved.

  20. Comparison of simultaneous distillation extraction and solid-phase micro-extraction for determination of volatile constituents in tobacco flavor

    Institute of Scientific and Technical Information of China (English)

    ZHONG Ke-jun; WEI Wan-zhi; GUO Fang-qiu; HUANG Lan-fang

    2005-01-01

    The volatile and semi-volatile components in tobacco flavor additives were extracted by both simultaneous distillation extraction and solid-phase micro-extraction. Extraction conditions for solid-phase micro-extraction were optimized with information theory. Then, detection were accomplished by gas chromatography-mass spectrometry. Characteristic of each method was compared. Qualitative analysis and quantitative analysis of 6# tobacco flavor sample were accomplished through both simultaneous distillation extraction and solid-phase micro-extraction. The experimental results show that solid-phase micro-extraction method is the first choice for qualitative analysis and simultaneous distillation extraction is another good selection for quantitative analysis. By means of simultaneous distillation extraction, 20 components are identified, accounting for 92.77% of the total peak areas. Through solid-phase micro-extraction, there are 17 components identified accounting for 91.49% of the total peak areas. The main aromatic components in 6# tobacco flavor sample are propanoic acid, 2-hydroxy-, ethyl ester, menthol and menthyl acetate. The presented method has been successfully used for quality control of tobacco flavor.

  1. DOES ENERGY CONSUMPTION VOLATILITY AFFECT REAL GDP VOLATILITY? AN EMPIRICAL ANALYSIS FOR THE UK

    Directory of Open Access Journals (Sweden)

    Abdul Rashid

    2013-10-01

    Full Text Available This paper empirically examines the relation between energy consumption volatility and unpredictable variations in real gross domestic product (GDP in the UK. Estimating the Markov switching ARCH model we find a significant regime switching in the behavior of both energy consumption and GDP volatility. The results from the Markov regime-switching model show that the variability of energy consumption has a significant role to play in determining the behavior of GDP volatilities. Moreover, the results suggest that the impacts of unpredictable variations in energy consumption on GDP volatility are asymmetric, depending on the intensity of volatility. In particular, we find that while there is no significant contemporaneous relationship between energy consumption volatility and GDP volatility in the first (low-volatility regime, GDP volatility is significantly positively related to the volatility of energy utilization in the second (high-volatility regime.

  2. Study on the calorific value determination method of high volatile coal%高挥发分煤发热量测定方法研究

    Institute of Scientific and Technical Information of China (English)

    郑伟强

    2016-01-01

    By adding different amount of asbestos board ash, the influence of which on the calorific value determination of high volatile coal was investigated.Meanwhile the results in four methods including wafering method, wrapping method, covering acid-washed asbestos method and blending asbestos board ash method were compared, it is pointed out that adding asbestos board ash could effectively solve the incidental splash problem in the calorific value determination of high volatile coal.%针对添加不同量的石棉板灰对高挥发分煤发热量的影响进行研究,并分别采用压饼法、包纸法、覆盖酸洗石棉法、石棉板灰混匀法4种方法对高挥发分煤样的发热量测定结果进行对比分析,指出添加石棉板灰可有效解决高挥发分煤在测定发热量时易飞溅的问题。

  3. Determination of Volatile Flavour Profiles of Citrus spp. Fruits by SDE-GC-MS and Enantiomeric Composition of Chiral Compounds by MDGC-MS.

    Science.gov (United States)

    Hong, Joon Ho; Khan, Naeem; Jamila, Nargis; Hong, Young Shin; Nho, Eun Yeong; Choi, Ji Yeon; Lee, Cheong Mi; Kim, Kyong Su

    2017-09-01

    Citrus fruits are known to have characteristic enantiomeric key compounds biosynthesised by highly stereoselective enzymatic mechanisms. In the past, evaluation of the enantiomeric ratios of chiral compounds in fruits has been applied as an effective indicator of adulteration by the addition of synthetic compounds or natural components of different botanical origin. To analyse the volatile flavour compounds of Citrus junos Sieb. ex Tanaka (yuzu), Citrus limon BURM. f. (lemon) and Citrus aurantifolia Christm. Swingle (lime), and determine the enantiomeric ratios of their chiral compounds for discrimination and authentication of extracted oils. Volatile flavour compounds of the fruits of the three Citrus species were extracted by simultaneous distillation extraction and analysed by gas chromatography-mass spectrometry. The enantiomeric composition (ee%) of chiral camphene, sabinene, limonene and β-phellandrene was analysed by heart-cutting multidimensional gas chromatography-mass spectrometry. Sixty-seven (C. junos), 77 (C. limon) and 110 (C. aurantifolia) volatile compounds were identified with limonene, γ-terpinene and linalool as the major compounds. Stereochemical analysis (ee%) revealed 1S,4R-(-) camphene (94.74, 98.67, 98.82), R-(+)-limonene (90.53, 92.97, 99.85) and S-(+)-β-phellandrene (98.69, 97.15, 92.13) in oil samples from all three species; R-(+)-sabinene (88.08) in C. junos; and S-(-)-sabinene (81.99, 79.74) in C. limon and C. aurantifolia, respectively. The enantiomeric composition and excess ratios of the chiral compounds could be used as reliable indicators of genuineness and quality assurance of the oils derived from the Citrus fruit species. Copyright © 2017 John Wiley & Sons, Ltd. Copyright © 2017 John Wiley & Sons, Ltd.

  4. Modification of determination of volatile phenols in drinking water%饮用水中挥发酚国标测定法的改进

    Institute of Scientific and Technical Information of China (English)

    陈静波; 方琴

    2011-01-01

    改进了国标法中对饮用水中挥发酚的测定方法,采用浓缩水样加碱蒸馏直接比色法代替国标法中的蒸馏萃取比色法。实验结果表明:改进后的方法标准曲线线性良好,回收率高,并且实验采用乙醇处理过的4氨基安替比林试剂,消除了空白管吸光值高的现象,提高了方法的灵敏度和结果的准确度。%The method of detecting volatile phenols in drinking water by national standard determination was improved.The extractive distillation colorimetry of national standard determination was replaced by alkali distillation colorimetry on concentrated water sam

  5. The development of an improved method for the determination of coal tar pitch volatiles (CTPV) in air.

    Science.gov (United States)

    Scobbie, E; Dabill, D W; Groves, J A

    1998-01-01

    Test samples were collected at a range of sites using the MDHS 68 sampler, a 7-hole sampler, and a cyclone respirable-dust sampler. Glass fibre, Zefluor, Fluoropore and silver (0.8 and 5 microns) filters were compared for weighing error, handling characteristics, and amount collected. The effects of a carbon back-up, of extraction solvent, and of analytical method were studied. The current HSE method for the sampling and analysis of coal tar pitch volatiles, MDHS 68 has been reviewed. It is recommended that the MDHS 68 sampler be replaced by a 7-hole head containing a silver or PTFE filter (approximately 1 micron pore size), with a graphitized carbon back-up if efficient collection of 2 to 4-ring PAHs is required. Cyclohexane is recommended as the extraction solvent. Methods of analysis which quantify the fume as a whole (MDHS 68, u.v., ELSD) were shown to give a response which varied according to the type of CTPV generating process. Therefore analysis of specific PAHs of occupational interest, by GC-MS or HPLC is recommended.

  6. Bacteria detection based on the evolution of enzyme-generated volatile organic compounds: determination of Listeria monocytogenes in milk samples.

    Science.gov (United States)

    Tait, Emma; Perry, John D; Stanforth, Stephen P; Dean, John R

    2014-10-27

    The rapid detection of Listeria monocytogenes contamination in food is essential to prevent food-borne illness in humans. The aim of this study was to differentiate non-contaminated milk from milk contaminated with L. monocytogenes using enzyme substrates coupled with the analysis of volatile organic compounds (VOCs). The method is based on the activity of β-glucosidase and hippuricase enzymes and the detection of a specific VOC i.e. 2-nitrophenol and 3-fluoroaniline, respectively. VOCs were extracted, separated and detected by headspace-solid phase microextraction coupled to gas chromatography-mass spectrometry (HS-SPME GC-MS). This approach required the inclusion of the selective agent's cycloheximide, nalidixic acid and acriflavine HCl in the growth medium to inhibit interfering bacteria. The VOCs were liberated by L. monocytogenes provided that samples contained at least 1-1.5×10(2) CFU ml(-1) of milk prior to overnight incubation. This approach shows potential for future development as a rapid method for the detection of L. monocytogenes contaminated milk.

  7. Analysis of Volatile Metabolites Released by Staphylococcus Aureus using Gas Chromatography-Mass Spectrometry and Determination of its Antifungal Activity

    Directory of Open Access Journals (Sweden)

    Hayfaa Hussein Jaddoa

    2016-08-01

    Full Text Available Bacterial volatile organic compounds (VOCs have been considered as sensitive and specific biomarkers for bacterial detection in human specimens and culture media. The possibility of using VOCs markers as one of the largest groups of bacterial metabolites would open a new frontier for developing more efficient techniques in the diagnosis of bacterial infections. The aims of this research were analysis of the bioactive chemical products and evaluation of antibacterial and antifungal activity. Bioactives (chemical compounds often referred to as secondary metabolites were analyzed using gas chromatography-mass spectroscopy (GC-MS techniques, then the in vitro antibacterial and antifungal activity of the methanolic extract was evaluated. Thirty five bioactive compounds were identified in the methanolic extract of Staphylococcus aureus. GC-MS analysis of Staphylococcus aureus revealed the existence of the: Hexanoic acid , 2-methyl, 12,15-Octadecadiynoic acid , methyl ester, 1-Aminononadecane ,N-trifluoroacetyl-, N-[3-[N-Aziridyl]propylidene]hexylamine, N-(2,5-Dicyano-3,4-dihydro-2H-pyrrol-2-yl-acetamide, 3-Cyclohex-3-enyl-propionic acid, 1-Methyl-4-[nitromethyl]-4-piperidinol, 3-Azonia-5-hexyn-1-ol , N,N-dimethyl-O-acetyl-,bromide, 1-Hexadecanol -2-methyl-, 1-Propyl-3,6-diazahomoadamantan, 9-Borabicyclo[3.3.1]nonane , 9-mercapto-, Benzyl methyl ketone, L-Aspartic acid ,N-glycyl-, Aminoacetamide , N-methyl-N-[4-(1-pyrrolidinyl-2-butynyl]-, Tertbutyloxyformamide , N-methyl-N-[4-(1-pyrrolidinyl-2-butyn, 5,7-Dodecadiyn-1,12-diol, Deoxyspergualin, D-Streptamine , O-6-deoxy-α-D-glucopyranosyl-(1-4, dl-Citrulline, N-[3-Diethylaminopropyl]-4-oxo-1,2,3,4,5,6,7,8-octahydroqui, N-Propionyl-D-glucoseamine, Cystine, 3,4-Dihydrocoumarin ,6-fluoro-4,4-dimethyl-, 4-(2,5-Dihydro-3-methoxyphenylbutylamine, 3-methoxy-2-(1-methylethyl-5-(2-methylpropylpyrazine, Uric acid, Thiocyanic acid 4-methoxy-2,6-dimethyl-3-pyridyl ester, 12-Dimethylamino-10-oxododecanoic acid

  8. Determination of 19 volatile organic compounds in wastewater effluents from different treatments by purge and trap followed by gas-chromatography coupled to mass spectrometry.

    Science.gov (United States)

    Barco-Bonilla, Nieves; Plaza-Bolaños, Patricia; Fernández-Moreno, José Luis; Romero-González, Roberto; Frenich, Antonia Garrido; Vidal, José Luis Martínez

    2011-07-01

    A rapid and simple methodology based on purge and trap with gas-chromatography coupled to triple quadrupole mass spectrometry has been developed for the analysis of 19 volatile organic compounds (VOCs) in wastewater (WW) effluents from four different treatments. The determination was carried out in the raw WW effluents, which were not submitted to any pre-treatment (e.g., filtration). A matrix effect study was also performed, concluding that solvent calibration was adequate to quantify VOCs in WW effluent samples containing a variety of suspended particulate matter. Adequate validation parameters were obtained with recovery values in the range 73-124% and precision values lower than 24%. Limits of quantification were established at 0.1 μg L(-1) for all VOCs. The proposed method was applied to the analysis of WW samples, detecting chloroform and toluene at concentrations ranging from 0.1 to 4.80 μg L(-1).

  9. Determination of geosmin, 2-methylisoborneol, and a musty-earthy odor in wheat grain by SPME-GC-MS, profiling volatiles, and sensory analysis.

    Science.gov (United States)

    Jeleń, Henryk H; Majcher, Małgorzata; Zawirska-Wojtasiak, Renata; Wiewiórowska, Małgorzata; Wasowicz, Erwin

    2003-11-19

    Geosmin and 2-methylisoborneol-compounds responsible for the musty-earthy off-odor of wheat grain, were isolated by SPME and analyzed by GC-MS. Carboxen/PDMS/DVB fiber coating was selected because of its highest extraction efficiency. Concentrations of geosmin and 2-methylisoborneol as low as 0.001 microg/kg were detected in SIM mode using ion trap mass spectrometer. Apart from GC-MS determination of geosmin and 2-methylisoborneol, various methods for evaluating the musty-earthy off-odor caused by these compounds in wheat grain are presented. Sensory profile analysis differentiated wheat grain into sound and off-flavored, but the method was tedious. Similar groupings, however, were obtained using more rapid methods such as comparison of volatile profiles using SPME-fast GC with PCA projection of data and metal oxide (MOS) based electronic nose.

  10. Comparison of two different passive air samplers (PUF-PAS versus SIP-PAS) to determine time-integrated average air concentration of volatile hydrophobic organic pollutants

    Science.gov (United States)

    Kim, Seung-Kyu; Park, Jong-Eun

    2014-06-01

    Despite remarkable achievements with r some chemicals, a field-measurement technique has not been advanced for volatile hydrophobic organic chemicals (HOCs) that are the subjects of international concern. This study assesses the applicability of passive air sampling (PAS) by comparing PUF-PAS and its modified SIP-PAS which was made by impregnating XAD-4 powder into PUF, overviewing the principles of PAS, screening sensitive parameters, and determining the uncertainty range of PAS-derived concentration. The PAS air sampling rate determined in this study, corrected by a co-deployed low-volume active air sampler (LAS) for neutral PFCs as model chemicals, was ˜1.2 m3 day-1. Our assessment shows that the improved sorption capacity in a SIP lengthens PAS deployment duration by expanding the linear uptake range and then enlarges the effective air sampling volume and detection frequency of chemicals at trace level. Consequently, volatile chemicals can be collected during sufficiently long times without reaching equilibrium when using SIP, while this is not possible for PUF. The most sensitive parameter to influence PAS-derived CA was an air-side mass transfer coefficient (kA), implying the necessity of spiking depuration chemicals (DCs) because this parameter is strongly related with meteorological conditions. Uncertainty in partition coefficients (KPSM-A or KOA) influences PAS-derived CA to a greater extent with regard to lower KPSM-A chemicals. Also, the PAS-derived CA has an uncertainty range of a half level to a 3-fold higher level of the calculated one. This work is expected to establish solid grounds for the improvement of field measurement technique of HOCs.

  11. Application of dispersive liquid-liquid microextraction and gas chromatography with mass spectrometry for the determination of oxygenated volatile organic compounds in effluents from the production of petroleum bitumen.

    Science.gov (United States)

    Boczkaj, Grzegorz; Makoś, Patrycja; Przyjazny, Andrzej

    2016-07-01

    We present a new procedure for the determination of oxygenated volatile organic compounds in samples of postoxidative effluents from the production of petroleum bitumens using dispersive liquid-liquid microextraction and gas chromatography with mass spectrometry. The eight extraction parameters were optimized for 43 oxygenated volatile organic compounds. The detection limits obtained ranged from 0.07 to 0.82 μg/mL for most of the analytes, the precision was good (relative standard deviation below 2.91% at the 5 μg/mL level and 4.75% at the limit of quantification), the recoveries for the majority of compounds varied from 70.6 to 118.9%, and the linear range was wide, which demonstrates the usefulness of the procedure. The developed procedure was used for the determination of oxygenated volatile organic compounds in samples of raw postoxidative effluents and in effluents after chemical treatment. In total, 23 compounds at concentration levels from 0.37 to 32.95 μg/mL were identified in real samples. The same samples were also analyzed in the SCAN mode, which resulted in four more phenol derivatives being identified and tentatively determined. The studies demonstrated the need for monitoring volatile organic compounds content in effluents following various treatments due to the formation of secondary oxygenated volatile organic compounds.

  12. 仙人掌超微粉挥发性成分研究%Determination of Chemical Constituents of the Volatile Oil from Opuntia dillenii (Ker-Gaw.) Haw

    Institute of Scientific and Technical Information of China (English)

    汪凯莎; 丁丽娜; 刘建华; 高玉琼; 安立群; 廖川

    2009-01-01

    目的:研究仙人掌中的挥发性成分.方法:利用水蒸气蒸馏法提取经超微粉碎后的仙人掌[Opuntia dillenii (Ker-Gaw.)Haw]挥发油,用GC-MS进行测定,结合计算机检索技术对分离的化合物进行结构鉴定,应用色谱峰面积归一化法计算各成分的相对百分含量.结果:共分离鉴定出32个化学成分,占总成分的98.097%,其中相对百分含量大于2%的分别确定为异丁基邻苯二甲酸酯(Isobutyl phthalate)27.492%,棕榈酸(Palmific acid)16.716%,丁基邻苯二甲酸酯(Butyl phthahte)11.257%,薄荷脑(Menthol)6.722%,亚油酸(Linoleic acid)5.995%,壬醛(Nonanal)4.594%,乙醛(Hexanal)3.614%,十二酸(Dodecanic acid)3.244%.结论:通过对仙人掌超微粉挥发性成分的分析鉴定及相对含量测定,为综合利用仙人掌植物资源等提供科学依据.%Objective: To study the chemical constituents of the volatile oil from Opuntia dillenii(Ker-Gaw.) Haw.Method: The chemical compositions of the volatile oil of the plants which were obtained by steam distillation with hexane were analyzed by GC-MS.The constituents were identified by their mass spectra.The relative percentage of the oil constituents was calculated from the GC peak areas.Result: Thirteen-two kinds of chemical constituents in Opuntia dillenii(Ker-Gaw.) Haw were separated and characterized;which were representing 98.097% of the oil.Relative contents that were more than 2% were determined as Isobutyl phthalate 27.492%,Palmitic acid 16.716%,Butyl phthalate 11.257%,Menthol 6.722%,Linoleic acid 5.995%,Nonanal 4.594%,Hexanal 3.614%,Dodecanic acid 3.244%.Conclusion: The composition of volatile oils of micro-milling of Opuntia dillenii(Ker-Gaw.) Haw's comprehensive utilization to provide reference data.

  13. Combining pH and electrical conductivity measurements to improve titrimetric methods to determine ammonia nitrogen, volatile fatty acids and inorganic carbon concentrations.

    Science.gov (United States)

    Charnier, C; Latrille, E; Lardon, L; Miroux, J; Steyer, J P

    2016-05-15

    Volatile fatty acids (VFA), inorganic carbon (IC) and total ammonia nitrogen (TAN) are key variables in the current context of anaerobic digestion (AD). Accurate measurements like gas chromatography and infrared spectrometry have been developed to follow the concentration of these compounds but none of these methods are affordable for small AD units. Only titration methods answer the need for small plant monitoring. The existing methods accuracy was assessed in this study and reveals a lack of accuracy and robustness to control AD plants. To solve these issues, a new titrimetric device to estimate the VFA, IC and TAN concentrations with an improved accuracy was developed. This device named SNAC (System of titration for total ammonia Nitrogen, volatile fatty Acids and inorganic Carbon) has been developed combining the measurement of electrical conductivity and pH. SNAC were tested on 24 different plant samples in a range of 0-0.16 mol.L(-1) TAN, 0.01-0.21 mol.L(-1) IC and 0-0.04 mol.L(-1) VFA. The standard error was about 0.012 mol.L(-1) TAN, 0.015 mol.L(-1) IC and 0.003 mol.L(-1) VFA. The coefficient of determination R(2) between the estimated and reference data was 0.95, 0.94 and 0.95 for TAN, IC and VFA respectively. Using the same data, current methods based on key pH points lead to standard error more than 14.5 times higher on VFA and more than 1.2 times higher on IC. These results show that SNAC is an accurate tool to improve the management of AD plant.

  14. Single-laboratory validation of a method for the determination of select volatile organic compounds in foods by using vacuum distillation with gas chromatography/mass spectrometry.

    Science.gov (United States)

    Nyman, Patricia J; Limm, William; Begley, Timothy H; Chirtel, Stuart J

    2014-01-01

    Recent studies showed that headspace and purge and trap methods have limitations when used to determine volatile organic compounds (VOCs) in foods, including matrix effects and artifact formation from precursors present in the sample matrix or from thermal decomposition. U.S. Environmental Protection Agency Method 8261A liberates VOCs from the sample matrix by using vacuum distillation at room temperature. The method was modified and validated for the determination of furan, chloroform, benzene, trichloroethene, toluene, and sytrene in infant formula, canned tuna (in water), peanut butter, and an orange beverage (orange-flavored noncarbonated beverage). The validation studies showed that the LOQ values ranged from 0.05 ng/g toluene in infant formula to 5.10 ng/g toluene in peanut butter. Fortified recoveries were determined at the first, second, and third standard additions, and concentrations ranged from 0.07 to 6.9 ng/g. When quantified by the method of standard additions, the recoveries ranged from 56 to 218% at the first standard addition and 89 to 117% at the third. The validated method was used to conduct a survey of the targeted VOCs in 18 foods. The amounts found ranged from none detected to 73.8 ng/g furan in sweet potato baby food.

  15. Pricing Volatility Referenced Assets

    Directory of Open Access Journals (Sweden)

    Alan De Genaro Dario

    2006-12-01

    Full Text Available Volatility swaps are contingent claims on future realized volatility. Variance swaps are similar instruments on future realized variance, the square of future realized volatility. Unlike a plain vanilla option, whose volatility exposure is contaminated by its asset price dependence, volatility and variance swaps provide a pure exposure to volatility alone. This article discusses the risk-neutral valuation of volatility and variance swaps based on the framework outlined in the Heston (1993 stochastic volatility model. Additionally, the Heston (1993 model is calibrated for foreign currency options traded at BMF and its parameters are used to price swaps on volatility and variance of the BRL / USD exchange rate.

  16. Determination of Chemical Constituents of Volatile Oil from Bulbophyllum odoratissimum%果上叶挥发性成分研究

    Institute of Scientific and Technical Information of China (English)

    盛世昌; 王道平; 刘建华; 高玉琼; 刘文炜; 李计龙

    2011-01-01

    目的:研究果上叶中的挥发性成分.方法:利用有机溶剂-水蒸气蒸馏法提取果上叶挥发油,用GC-MS进行测定,结合计算机检索技术对分离化合物进行结构鉴定,应用色谱峰面积归一化法计算各成分的相对百分含量.结果:分离鉴定出38种化学成分,占挥发油总量91.448%,其中含量大于2%的分别为Z-9-十八烯醛18.075%、2,4-二叔丁基苯酚3.264%、棕榈酸5.413%、油酸25.079%、二十三烷6.344%、二十四烷3.768%、1-十八烯酸单甘油酯2.146%、亚油酸甘油酯4.953%、二十五烷4.332%、二十六烷3.387%、二十七烷3.841%、二十八烷3.102%.结论:本文采用气相色谱-质谱联用法对果上叶中的挥发性成分进行研究.%Objective:To study the chemical constituents of the volatile oil from Bulbophyllum odoratissimum. Method: The chemical compositions of the volatile oil of the plants which were obtained by organic-steam distillation with hexane were analyzed by GC-MS. The constituents were identified by their mass spectra. The relative percentage of the oil constituents was calculated from the GC peak areas. Result: Thirty-eight kinds of chemical components were identified from B. odoratissimum. The amount of the identified components was accounted for 91. 448% of all the volatile oil. The constituents whose relative content was more than 2% were determined as Z-9-octadecenal (18. 075% ), 2,4-Di-tertbutylphenol (3.264%), palmitic acid (5.413%), oleic acid (25.079%),tricosane (6. 344% ), tetracosane (3. 768% ), 1-Monoolein (2. 416% ), 1-monolinolein (4. 953% ), pontacosane (4. 332% ), hexacosane (3. 387% ), heptacosane (3. 841% ), octacosane (3. 102% ). Conclusion: The composition of volatile oils from B. odoratissimum by GC-MS.

  17. Determination of volatile fractions in raw milk and ripened cheese by means of GC-MS. Results of a survey performed in the marginal area between Italy and Slovenia

    Directory of Open Access Journals (Sweden)

    Bruno Stefanon

    2010-01-01

    Full Text Available The volatile fractions of milk and their evolution in ripened cheese were studied using purge and trap extraction and gas chromatography-mass spectrometry analysis (GC-MS. Eighteen samples of raw milk and cheese ripened for 70 days were collected in 2 consecutive years from dairy farms located in the border area between Italy and Slovenia. Twenty one volatile compounds not detected in the fresh milk used for cheese manufacturing, belonging mainly to the class of esters and alcohols, were found, while 8 compounds detected in milk were not found in cheese after 70 days of ripening. In cheese the majority of compounds increased significantly, even though the variations differed between the classes of volatile compounds. Concentration of alcohols, in particular ethanol, 1-propanol, 2-propanol, 3-methyl-1-butanol and 2-pentanol, increased considerably, while the content of ketones and terpenes was characterized by a significant, although small, rise that was largely related to a quantitative variation of only few compounds. Also esters, despite the high number of volatile compounds of new formation, showed a lower increase of concentration than that observed for the alcohols. Concentration of aldehydes, hydrocarbons and sulphur compounds remained unchanged, despite relevant variations involving the individual chemical compounds. Significant differences were also observed between the dairy product of the two countries, mainly for the concentration of volatile compounds belonging to the classes of alcohols, ketones and esters.

  18. Determination of a wide range of volatile organic compounds in ambient air using multisorbent adsorption/thermal desorption and gas chromatography/mass spectrometry

    Science.gov (United States)

    Pankow, J.F.; Luo, W.; Isabelle, L.M.; Bender, D.A.; Baker, R.J.

    1998-01-01

    Adsorption/thermal desorption with multisorbent air-sampling cartridges was developed for the determination of 87 method analytes including halogenated alkanes, halogenated alkenes, ethers, alcohols, nitriles, esters, ketones, aromatics, a disulfide, and a furan. The volatilities of the compounds ranged from that of dichlorofluoromethane (CFC12) to that of 1,2,3- trichlorobenzene. The eight most volatile compounds were determined using a 1.5-L air sample and a sample cartridge containing 50 mg of Carbotrap B and 280 mg of Carboxen 1000; the remaining 79 compounds were determined using a 5-L air sample and a cartridge containing 180 mg of Carbotrap B and 70 mg of Carboxen 1000. Analysis and detection were by gas chromatography/mass spectrometry. The minimum detectable level (MDL) concentration values ranged from 0.01 parts per billion by volume (ppbv) for chlorobenzene to 0.4 ppbv for bromomethane; most of the MDL values were in the range 0.02-0.06 ppbv. No breakthrough was detected with the prescribed sample volumes. Analyte stability on the cartridges was very good. Excellent recoveries were obtained with independent check standards. Travel spike recoveries ranged from 90 to 110% for 72 of the 87 compounds. The recoveries were less than 70% for bromomethane and chloroethene and for a few compounds such as methyl acetate that are subject to losses by hydrolysis; the lowest travel spike recovery was obtained for bromomethane (62%). Blank values for all compounds were either below detection or very low. Ambient atmospheric sampling was conducted in New Jersey from April to December, 1997. Three sites characterized by low, moderate, and high densities of urbanization/traffic were sampled. The median detected concentrations of the compounds were either similar at all three sites (as with the chlorofluorocarbon compounds) or increased with the density of urbanization/traffic (as with dichloromethane, MTBE, benzene, and toluene). For toluene, the median detected

  19. Determining the Levels of Volatile Organic Pollutants in Urban Air Using a Gas Chromatography-Mass Spectrometry Method

    OpenAIRE

    Simona Nicoara; Loris Tonidandel; Pietro Traldi; Jonathan Watson; Geraint Morgan; Ovidiu Popa

    2009-01-01

    The paper presents the application of a method based on coupled gas chromatography-mass spectrometry, using an isotopically labelled internal standard for the quantitative analysis of benzene (B), toluene (T), ethyl benzene (E), and o-, m-, p-xylenes (X). Their atmospheric concentrations were determined based on short-term sampling, in different sites of Cluj-Napoca, a highly populated urban centre in N-W Romania, with numerous and diversified road vehicles with internal combustion engines. T...

  20. Flow injection determination of Se in dietary supplements using TiO2 mediated ultraviolet-photochemical volatile species generation

    Science.gov (United States)

    Nováková, E.; Linhart, O.; Červený, V.; Rychlovský, P.; Hraníček, J.

    2017-08-01

    This paper proposes a method for determination of selenium content in samples of dietary supplements using TiO2 mediated UV-photochemical vapor generation with quartz furnace atomic spectrometric detection. The flow-injection method was optimized for determination of selenium in the form of selenite or selenate ions. The limits of detection of the proposed method are 0.89 ng mL- 1 and 0.68 ng mL- 1 for selenite and selenate, respectively. Extraction in neutral medium was used for the leaching of selenate and NaOH solution was used for the leaching of selenite. The methods accuracy was verified against the declared amounts of Se in five different samples of over-the-counter dietary supplements and on NIST SRM 3280. The method was also compared to results achieved with determination by electrothermal atomization atomic absorption spectrometry following microwave decomposition. The recovery of selenium during sample preparation was tested by spiking the tablets prior to extraction and estimated to be approximately 100%. An interference study has been carried out to estimate the effect of concomitant elements on the methods accuracy.

  1. Determination of volatile components of saffron by optimised ultrasound-assisted extraction in tandem with dispersive liquid-liquid microextraction followed by gas chromatography-mass spectrometry.

    Science.gov (United States)

    Sereshti, Hassan; Heidari, Reza; Samadi, Soheila

    2014-01-15

    In the present research, a combined extraction method of ultrasound-assisted extraction (UAE) in conjunction with dispersive liquid-liquid microextraction (DLLME) was applied to isolation and enrichment of saffron volatiles. The extracted components of the saffron were separated and determined by gas chromatography-mass spectrometry (GC-MS) technique. The mixture of methanol/acetonitrile was chosen for the extraction of the compounds and chloroform was used at the preconcentration stage. The important parameters, such as composition of extraction solvent, volume of preconcentration solvent, ultrasonic applying time, and salt concentration were optimised by using a half-fraction factorial central composite design (CCD). Under the optimal conditions, the linear dynamic ranges (LDRs) were 10-10,000mgL(-)(1). The determination coefficients (R(2)) were from 0.9990 to 0.9997. The limits of detection (LODs) and limits of quantification (LOQs) for the extracted compounds were 6-123mgL(-)(1) and 20-406mgL(-)(1), respectively. The relative standard deviations (RSDs) were 2.48-9.82% (n=3). The enhancement factors (EFs) were 3.6-41.3.

  2. Determination and Control Measures of Indoor Volatile Organic Compounds%室内挥发性有机污染物的测定方法与防治措施

    Institute of Scientific and Technical Information of China (English)

    谢振键

    2015-01-01

    This paper analyzes the indoor volatile organic compounds and their sources, describes the volatile organic compounds on human health hazard and conventional determination of volatile organic compounds. From the building materials, purify air, this paper puts forward the indoor pollution prevention and control measures.%本文分析了室内环境挥发性有机化合物的来源,描述了挥发性有机化合物对人体健康的危害性及常规挥发性有机化合物的测定,并从建筑材料、净化空气等方面提出了室内污染的防治措施。

  3. The sensitivity of Secondary Organic Aerosol component partitioning to the predictions of component properties – Part 2: Determination of particle hygroscopicity and its dependence on "apparent" volatility

    Directory of Open Access Journals (Sweden)

    D. O. Topping

    2011-08-01

    Full Text Available A large number of calculations of absorptive partitioning of organic compounds have been conducted, making use of several methods to estimate pure component vapour pressures and activity coefficients (p0 and γi. The sensitivities of the predicted particle properties (density, hygroscopicity, CCN activation potential to the choice of p0 and γi models and to the number of components used to represent the organic mixture have been systematically compared.

    The variability in theoretical hygroscopic growth factor attributable to the choice of estimation technique increases with decreasing mixture complexity. Generally there is low sensitivity to the choice of vapour pressure predictive technique. The inclusion of non-ideality is responsible for a larger difference in predicted growth factor, though still relatively minor.

    Assuming instantaneous equilibration of all semi-volatile on drying the aerosol to 0 % RH massively increases the sensitivity. Without such re-equilibration, the calculated growth factors are comparable to the low hygroscopicity of organic material widely measured in the laboratory and atmosphere. Allowing re-equilibration on drying produces a calculated hygroscopicity greater than measured for ambient organic material, and frequently close to those of common inorganic salts. Such a result has substantial implications on aerosol behaviour in instruments designed to measure hygroscopicity and on the degree of equilibration of semi-volatile components in the ambient atmosphere.

    The impacts of this variability on behaviour of particles as cloud condensation nuclei, on predicted cloud droplet number and uncertainty in radiative forcing are explored. When it is assumed only water evaporates on drying, the sensitivity in radiative forcing, "ΔF" to choice of p0 and γi estimation technique is low

  4. Determining the Levels of Volatile Organic Pollutants in Urban Air Using a Gas Chromatography-Mass Spectrometry Method

    Directory of Open Access Journals (Sweden)

    Simona Nicoara

    2009-01-01

    Full Text Available The paper presents the application of a method based on coupled gas chromatography-mass spectrometry, using an isotopically labelled internal standard for the quantitative analysis of benzene (B, toluene (T, ethyl benzene (E, and o-, m-, p-xylenes (X. Their atmospheric concentrations were determined based on short-term sampling, in different sites of Cluj-Napoca, a highly populated urban centre in N-W Romania, with numerous and diversified road vehicles with internal combustion engines. The method is relatively inexpensive and simple and shows good precision and linearity in the ranges of 7–60 μg/m3 (B, 13–90 μg/m3 (T, 7–50 μg/m3 (E, 10–70 μg/m3 (X-m,p, and 20–130 μg/m3 (X-o. The limits of quantitation/detection of the method LOQ/LOD are of 10/5 μg/m3 (Xo, 5/3 μg/m3 (B, E, X-m,p, and of 3/1 μg/m3 (T, respectively.

  5. Determination of volatile organic compounds in water by headspace solid-phase microextraction gas chromatography coupled to tandem mass spectrometry with triple quadrupole analyzer.

    Science.gov (United States)

    Cervera, M I; Beltran, J; Lopez, F J; Hernandez, F

    2011-10-17

    In the present work, a rapid method with little sample handling has been developed for determination of 23 selected volatile organic compounds in environmental and wastewater samples. The method is based on headspace solid-phase microextraction (SPME) followed by gas chromatography coupled to tandem mass spectrometry (GC-MS/MS) determination using triple quadrupole analyzer (QqQ) in electron ionization mode. The best conditions for extraction were optimised with a factorial design taking into account the interaction between different parameters and not only individual effects of variables. In the optimized procedure, 4 mL of water sample were extracted using a 10 mL vial and adding 0.4 g NaCl (final NaCl content of 10%). An SPME extraction with carboxen/polydimethylsiloxane 75 μm fiber for 30 min at 50°C (with 5 min of previous equilibration time) with magnetic stirring was applied. Chromatographic determination was carried out by GC-MS/MS working in Selected Reaction Monitoring (SRM) mode. For most analytes, two MS/MS transitions were acquired, although for a few compounds it was difficult to obtain characteristic abundant fragments. In those cases, a pseudo selected reaction monitoring (pseudo-SRM) with three ions was used instead. The intensity ratio between quantitation (Q) and confirmation (q) signals was used as a confirmatory parameter. The method was validated by means of recovery experiments (n=6) spiking mineral water samples at three concentration levels (0.1, 5 and 50 μg L(-1)). Recoveries between 70% and 120% were generally obtained with relative standard deviations (RSDs) lower than 20%. The developed method was applied to surface water and wastewater from a wastewater treatment plant and from a municipal solid-waste treatment plant. Several compounds, like chloroform, benzene, trichloroethylene, toluene, tetrachloroethylene, dibromochloromethane, xylenes and bromoform were detected and confirmed in all the samples analyzed.

  6. The gas chromatographic determination of volatile fatty acids in wastewater samples: evaluation of experimental biases in direct injection method against thermal desorption method.

    Science.gov (United States)

    Ullah, Md Ahsan; Kim, Ki-Hyun; Szulejko, Jan E; Cho, Jinwoo

    2014-04-11

    The production of short-chained volatile fatty acids (VFAs) by the anaerobic bacterial digestion of sewage (wastewater) affords an excellent opportunity to alternative greener viable bio-energy fuels (i.e., microbial fuel cell). VFAs in wastewater (sewage) samples are commonly quantified through direct injection (DI) into a gas chromatograph with a flame ionization detector (GC-FID). In this study, the reliability of VFA analysis by the DI-GC method has been examined against a thermal desorption (TD-GC) method. The results indicate that the VFA concentrations determined from an aliquot from each wastewater sample by the DI-GC method were generally underestimated, e.g., reductions of 7% (acetic acid) to 93.4% (hexanoic acid) relative to the TD-GC method. The observed differences between the two methods suggest the possibly important role of the matrix effect to give rise to the negative biases in DI-GC analysis. To further explore this possibility, an ancillary experiment was performed to examine bias patterns of three DI-GC approaches. For instance, the results of the standard addition (SA) method confirm the definite role of matrix effect when analyzing wastewater samples by DI-GC. More importantly, their biases tend to increase systematically with increasing molecular weight and decreasing VFA concentrations. As such, the use of DI-GC method, if applied for the analysis of samples with a complicated matrix, needs a thorough validation to improve the reliability in data acquisition.

  7. Determination of the volatile fraction of Polygonum bistorta L. at different growing stages and evaluation of its antimicrobial activity against two major honeybee (Apis mellifera) pathogens.

    Science.gov (United States)

    Cecotti, Roberto; Carpana, Emanuele; Falchero, Luca; Paoletti, Renato; Tava, Aldo

    2012-02-01

    The composition of the volatile fraction of Polygonum bistorta L. (also known as bistort or snakeroot) was investigated. Fresh aerial parts of this plant species were collected in the Western Italian Alps during the summer at three different phenological stages, namely vegetative, flowering, and fruiting, and steam-distilled in a Clevenger-type apparatus. The oils accounted for 0.004 to 0.010% of the fresh plant material, and their compositions were determined by GC/FID and GC/MS. The composition of the oils during the vegetative period varied both in quantity and quality; several classes of compounds were found with a predominance of alcohols in the vegetative phase, terpenes and linear-chained saturated hydrocarbons in the flowering phase, while saturated aliphatic acids and their methyl esters were predominant in fruiting phase. The most abundant compounds were 3-methylbut-3-en-1-ol in the vegetative phase, linalool in the flowering phase, and dodecanoic acid and its methyl ester in the fruiting phase. The obtained essential oils were then tested against two major bee pathogens, i.e., Paenibacillus larvae and Melissococcus plutonius, and against a reference bacterial species, Bacillus subtilis. Data were compared to those obtained with reference standards used against those pathogens such as the essential oils obtained from leaves and bark of Cinnamomum zeylanicum (cinnamon), and the antibiotic oxytetracyclin.

  8. Determination of hydroxycinnamic acids and volatile phenols in wort and beer by isocratic high-performance liquid chromatography using electrochemical detection.

    Science.gov (United States)

    Vanbeneden, Nele; Delvaux, Filip; Delvaux, Freddy R

    2006-12-15

    The suitability of a simple and rapid isocratic RP-HPLC method with amperometric electrochemical detection for the simultaneous detection and quantification of hydroxycinnamic acids and their corresponding aroma-active volatile phenols in wort and beer is reported. The technique gives good specificity and sensitivity, and can therefore be used for routine monitoring of hydroxycinnamic acids in wort and the development of volatile phenolic flavour compounds during the beer production process and subsequent conservation.

  9. Study of tellurium determination through volatile hydride and direct introduction to a plasma spectrometer of low power. Estudio de la determinacion de Teluro mediante la generacion e introduccion de su hidruro en plasmas de acoplamiento inductivo (ICP) de baja potencia

    Energy Technology Data Exchange (ETDEWEB)

    Lopez Molinero, A.; Barriovero, O.; Lechon, J.M.; Castillo, J.R. (Universidad de Zaragoza. Facultad de Ciencias. Departamento de Quimica Analitica. Zaragoza (Spain))

    1993-01-01

    Tellurium has been determined by AES-ICP at 214,282 nm with a detection limit of 4 ng/ml and a relative standard deviation (r.s.d.) of 3.0/. These performances have been attained via generation of the volatile hydride and direct introduction to a plasma spectrometer of low power. This analytical method has been applied to Te determination in plastic additives. (Author) 17 refs.

  10. SNC meteorites and their implications for reservoirs of Martian volatiles

    Science.gov (United States)

    Jones, J. H.

    1993-01-01

    The SNC meteorites and the measurements of the Viking landers provide our only direct information about the abundance and isotopic composition of Martian volatiles. Indirect measurements include spectroscopic determinations of the D/H ratio of the Martian atmosphere. A personal view of volatile element reservoirs on Mars is presented, largely as inferred from the meteoritic evidence. This view is that the Martian mantle has had several opportunities for dehydration and is most likely dry, although not completely degassed. Consequently, the water contained in SNC meteorites was most likely incorporated during ascent through the crust. Thus, it is possible that water can be decoupled from other volatile/incompatible elements, making the SNC meteorites suspect as indicators of water inventories on Mars.

  11. Assessing inter-laboratory comparability and limits of determination for the analysis of cyclic volatile methyl siloxanes in whole Rainbow Trout (Oncorhynchus mykiss).

    Science.gov (United States)

    McGoldrick, Daryl J; Durham, Jeremy; Leknes, Henriette; Kierkegaard, Amelie; Gerhards, Reinhard; Powell, David E; McLachlan, Michael S

    2011-11-01

    Cyclic volatile methyl siloxanes (cVMS) are high volume production chemicals used in a wide range of industrial and consumer products. Three cVMS compounds (D4, D5, and D6) have and are undergoing environmental risk evaluations in several countries and have been proposed for legal regulation in Canada. As interest in monitoring concentrations of these chemicals in the environment increase, there is a need to evaluate the analytical procedures for cVMS in biological matrices in order to assess the quality of data produced. The purpose of this study was to determine laboratory testing performance for measuring residues of D4, D5, and D6 in a standard set of fish homogenate samples and to estimate limits of determination for each substance. The samples sent to each laboratory consisted of homogenized whole body tissues of hatchery raised rainbow trout which were fed food fortified with D4, D5, and D6 (dosed) and trout that were fed standard food rations (control). The participants analyzed each sample using their analytical method of choice using their own standards and procedures for quantification and quality control. With a few exceptions, participating laboratories generated comparable results for D4, D5, and D6 in both the dosed and control samples having z-scores between 2 and -2. Method detection limits for the whole fish matrix were on average 2.4 ng g(-1) ww for D4, 2.3 ng g(-1) ww for D5, and 1.8 ng g(-1) ww for D6.

  12. Particularities for determination stress state components of large radius curvature ring expansion process

    Directory of Open Access Journals (Sweden)

    Petrosyan G.L.

    2012-09-01

    Full Text Available The peculiarities for determining the current interconnected geometrical parameters of large diameter ring expansion process are revealed. Based on ring stress state studies the universal system of equations is obtained. It is shown that in case of step-by-step increase of ring diameter the changes of geometrical parameters allow to obtain the equations of plane stripe rolling.

  13. Determinants of salivary evening alpha-amylase in a large sample free of psychopathology

    NARCIS (Netherlands)

    Veen, Gerthe; Giltay, Erik J.; Vreeburg, Sophie A.; Licht, Carmilla M. M.; Cobbaert, Christa M.; Zitman, Frans G.; Penninx, Brenda W. J. H.

    2012-01-01

    Objective: Recently, salivary alpha-amylase (sAA) has been proposed as a suitable index for sympathetic activity and dysregulation of the autonomic nervous system (ANS). Although determinants of sAA have been described, they have not been studied within the same study with a large sample size withou

  14. Determinants of salivary evening alpha-amylase in a large sample free of psychopathology

    NARCIS (Netherlands)

    Veen, Gerthe; Giltay, Erik J.; Vreeburg, Sophie A.; Licht, Carmilla M. M.; Cobbaert, Christa M.; Zitman, Frans G.; Penninx, Brenda W. J. H.

    Objective: Recently, salivary alpha-amylase (sAA) has been proposed as a suitable index for sympathetic activity and dysregulation of the autonomic nervous system (ANS). Although determinants of sAA have been described, they have not been studied within the same study with a large sample size

  15. Determination of volatile organic compounds in water by headspace solid-phase microextraction gas chromatography coupled to tandem mass spectrometry with triple quadrupole analyzer

    Energy Technology Data Exchange (ETDEWEB)

    Cervera, M.I. [Research Institute for Pesticides and Water, University Jaume I, Avda. Sos Baynat, E-12071 Castellon (Spain); Beltran, J., E-mail: joaquim.beltran@uji.es [Research Institute for Pesticides and Water, University Jaume I, Avda. Sos Baynat, E-12071 Castellon (Spain); Lopez, F.J.; Hernandez, F. [Research Institute for Pesticides and Water, University Jaume I, Avda. Sos Baynat, E-12071 Castellon (Spain)

    2011-10-17

    Highlights: {yields} Employing a statistical optimization improves results reducing experiments. {yields} Use of MS (QqQ) allows high sensitivity determination and improves identification capabilities. {yields} Using Q/q intensity ratios is a powerful tool to ensure compound identification. {yields} HS SPME GC-MS/MS method allows determination of VOCs in complex matrix water samples. - Abstract: In the present work, a rapid method with little sample handling has been developed for determination of 23 selected volatile organic compounds in environmental and wastewater samples. The method is based on headspace solid-phase microextraction (SPME) followed by gas chromatography coupled to tandem mass spectrometry (GC-MS/MS) determination using triple quadrupole analyzer (QqQ) in electron ionization mode. The best conditions for extraction were optimised with a factorial design taking into account the interaction between different parameters and not only individual effects of variables. In the optimized procedure, 4 mL of water sample were extracted using a 10 mL vial and adding 0.4 g NaCl (final NaCl content of 10%). An SPME extraction with carboxen/polydimethylsiloxane 75 {mu}m fiber for 30 min at 50 deg. C (with 5 min of previous equilibration time) with magnetic stirring was applied. Chromatographic determination was carried out by GC-MS/MS working in Selected Reaction Monitoring (SRM) mode. For most analytes, two MS/MS transitions were acquired, although for a few compounds it was difficult to obtain characteristic abundant fragments. In those cases, a pseudo selected reaction monitoring (pseudo-SRM) with three ions was used instead. The intensity ratio between quantitation (Q) and confirmation (q) signals was used as a confirmatory parameter. The method was validated by means of recovery experiments (n = 6) spiking mineral water samples at three concentration levels (0.1, 5 and 50 {mu}g L{sup -1}). Recoveries between 70% and 120% were generally obtained with

  16. Volatiles in Inter-Specific Bacterial Interactions.

    Science.gov (United States)

    Tyc, Olaf; Zweers, Hans; de Boer, Wietse; Garbeva, Paolina

    2015-01-01

    The importance of volatile organic compounds for functioning of microbes is receiving increased research attention. However, to date very little is known on how inter-specific bacterial interactions effect volatiles production as most studies have been focused on volatiles produced by monocultures of well-described bacterial genera. In this study we aimed to understand how inter-specific bacterial interactions affect the composition, production and activity of volatiles. Four phylogenetically different bacterial species namely: Chryseobacterium, Dyella, Janthinobacterium, and Tsukamurella were selected. Earlier results had shown that pairwise combinations of these bacteria induced antimicrobial activity in agar media whereas this was not the case for monocultures. In the current study, we examined if these observations were also reflected by the production of antimicrobial volatiles. Thus, the identity and antimicrobial activity of volatiles produced by the bacteria were determined in monoculture as well in pairwise combinations. Antimicrobial activity of the volatiles was assessed against fungal, oomycetal, and bacterial model organisms. Our results revealed that inter-specific bacterial interactions affected volatiles blend composition. Fungi and oomycetes showed high sensitivity to bacterial volatiles whereas the effect of volatiles on bacteria varied between no effects, growth inhibition to growth promotion depending on the volatile blend composition. In total 35 volatile compounds were detected most of which were sulfur-containing compounds. Two commonly produced sulfur-containing volatile compounds (dimethyl disulfide and dimethyl trisulfide) were tested for their effect on three target bacteria. Here, we display the importance of inter-specific interactions on bacterial volatiles production and their antimicrobial activities.

  17. Volatiles in inter-specific bacterial interactions

    Directory of Open Access Journals (Sweden)

    Olaf eTyc

    2015-12-01

    Full Text Available The importance of volatile organic compounds for functioning of microbes is receiving increased research attention. However, to date very little is known on how inter-specific bacterial interactions effect volatiles production as most studies have been focused on volatiles produced by monocultures of well described bacterial genera. In this study we aimed to understand how inter-specific bacterial interactions affect the composition, production and activity of volatiles. Four phylogenetically different bacterial species namely: Chryseobacterium, Dyella, Janthinobacterium and Tsukamurella were selected. Earlier results had shown that pairwise combinations of these bacteria induced antimicrobial activity in agar media whereas this was not the case for monocultures. In the current study, we examined if these observations were also reflected by the production of antimicrobial volatiles. Thus, the identity and antimicrobial activity of volatiles produced by the bacteria were determined in monoculture as well in pairwise combinations. Antimicrobial activity of the volatiles was assessed against fungal, oomycetal and bacterial model organisms. Our results revealed that inter-specific bacterial interactions affected volatiles blend composition. Fungi and oomycetes showed high sensitivity to bacterial volatiles whereas the effect of volatiles on bacteria varied between no effects, growth inhibition to growth promotion depending on the volatile blend composition. In total 35 volatile compounds were detected most of which were sulfur-containing compounds. Two commonly produced sulfur-containing volatile compounds (dimethyl disulfide and dimethyl trisulfide were tested for their effect on three target bacteria. Here we display the importance of inter-specific interactions on bacterial volatiles production and their antimicrobial activities.

  18. Determination of hydrogen sulfide and volatile thiols in air samples by mercury probe derivatization coupled with liquid chromatography-atomic fluorescence spectrometry.

    Science.gov (United States)

    Bramanti, Emilia; D'Ulivo, Lucia; Lomonte, Cristina; Onor, Massimo; Zamboni, Roberto; Raspi, Giorgio; D'Ulivo, Alessandro

    2006-10-02

    A new procedure is proposed for the sampling and storage of hydrogen sulphide (H2S) and volatile thiols (methanethiol or methyl mercaptan, ethanethiol and propanethiol) for their determination by liquid chromatography. The sampling procedure is based on the trapping/pre-concentration of the analytes in alkaline aqueous solution containing an organic mercurial probe p-hydroxymercurybenzoate, HO-Hg-C6H4-COO- (PHMB), where they are derivatized to stable PHMB complexes based on mercury-sulfur covalent bonds. PHMB complexes are separated on a C18 reverse phase column, allowing their determination by liquid chromatography coupled with sequential non-selective UV-vis (DAD) and mercury specific (chemical vapor generation atomic fluorescence spectrometry, CVGAFS) on-line detectors. PHMB complexes, S(PHMB)2CH3S-PHMB, C2H5S-PHMB and C3H7S-PHMB, are stable alt least for 12 h at room temperature and for 3 months if stored frozen (-20 degrees C). The best analytical figures of merits in the optimized conditions were obtained by CVGAFS detection, with detection limits (LODc) of 9.7 microg L(-1) for H2S, 13.7 microg L(-1) for CH(3)SH, 17.7 microg L(-1) for C2H5SH and 21.7 microg L(-1) for C3H7SH in the trapping solution in form of RS-PHMB complexes, the relative standard deviation (R.S.D.) ranging between 1.0 and 1.5%, and a linear dynamic range (LDR) between 10 and 9700 microg L(-1). Conventional UV absorbance detectors tuned at 254 nm can be employed as well with comparable R.S.D. and LDR, but with LODc one order of magnitude higher than AFS detector and lower specificity. The sampling procedure followed by LC-DAD-CVGAFS analysis has been validated, as example, for H2S determination by a certified gas permeation tube as a source of 3.071+/-0.154 microg min(-1) of H2S, giving a recovery of 99.8+/-7% and it has been applied to the determination of sulfur compounds in real gas samples (biogas and the air of a plant for fractional distillation of crude oil).

  19. Determination of hydrogen sulfide and volatile thiols in air samples by mercury probe derivatization coupled with liquid chromatography-atomic fluorescence spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Bramanti, Emilia [Italian National Research Council, CNR-Istituto per i Processi Chimico-Fisici, Laboratory of Instrumental Analytical Chemistry, Via G. Moruzzi 1, 56124 Pisa (Italy)]. E-mail: emilia@ipcf.cnr.it; D' Ulivo, Lucia [Italian National Research Council, CNR-Istituto per i Processi Chimico-Fisici, Laboratory of Instrumental Analytical Chemistry, Via G. Moruzzi 1, 56124 Pisa (Italy); Lomonte, Cristina [Italian National Research Council, CNR-Istituto per i Processi Chimico-Fisici, Laboratory of Instrumental Analytical Chemistry, Via G. Moruzzi 1, 56124 Pisa (Italy); Ambiente s.c.r.l., Via Frassina 21, 54033, Carrrara, Massa (Italy); Onor, Massimo [Italian National Research Council, CNR-Istituto per i Processi Chimico-Fisici, Laboratory of Instrumental Analytical Chemistry, Via G. Moruzzi 1, 56124 Pisa (Italy); Zamboni, Roberto [Department of Chemistry and Industrial Chemistry, University of Pisa, Via Risorgimento 35, 56126 Pisa (Italy); Raspi, Giorgio [Italian National Research Council, CNR-Istituto per i Processi Chimico-Fisici, Laboratory of Instrumental Analytical Chemistry, Via G. Moruzzi 1, 56124 Pisa (Italy); D' Ulivo, Alessandro [Italian National Research Council, CNR-Istituto per i Processi Chimico-Fisici, Laboratory of Instrumental Analytical Chemistry, Via G. Moruzzi 1, 56124 Pisa (Italy)

    2006-10-02

    A new procedure is proposed for the sampling and storage of hydrogen sulphide (H{sub 2}S) and volatile thiols (methanethiol or methyl mercaptan, ethanethiol and propanethiol) for their determination by liquid chromatography. The sampling procedure is based on the trapping/pre-concentration of the analytes in alkaline aqueous solution containing an organic mercurial probe p-hydroxymercurybenzoate, HO-Hg-C{sub 6}H{sub 4}-COO{sup -} (PHMB), where they are derivatized to stable PHMB complexes based on mercury-sulfur covalent bonds. PHMB complexes are separated on a C{sub 18} reverse phase column, allowing their determination by liquid chromatography coupled with sequential non-selective UV-vis (DAD) and mercury specific (chemical vapor generation atomic fluorescence spectrometry, CVGAFS) on-line detectors. PHMB complexes, S(PHMB){sub 2}CH{sub 3}S-PHMB, C{sub 2}H{sub 5}S-PHMB and C{sub 3}H{sub 7}S-PHMB, are stable alt least for 12 h at room temperature and for 3 months if stored frozen (-20 deg. C). The best analytical figures of merits in the optimized conditions were obtained by CVGAFS detection, with detection limits (LODc) of 9.7 {mu}g L{sup -1} for H{sub 2}S, 13.7 {mu}g L{sup -1} for CH{sub 3}SH, 17.7 {mu}g L{sup -1} for C{sub 2}H{sub 5}SH and 21.7 {mu}g L{sup -1} for C{sub 3}H{sub 7}SH in the trapping solution in form of RS-PHMB complexes, the relative standard deviation (R.S.D.) ranging between 1.0 and 1.5%, and a linear dynamic range (LDR) between 10 and 9700 {mu}g L{sup -1}. Conventional UV absorbance detectors tuned at 254 nm can be employed as well with comparable R.S.D. and LDR, but with LODc one order of magnitude higher than AFS detector and lower specificity. The sampling procedure followed by LC-DAD-CVGAFS analysis has been validated, as example, for H{sub 2}S determination by a certified gas permeation tube as a source of 3.071 {+-} 0.154 {mu}g min{sup -1} of H{sub 2}S, giving a recovery of 99.8 {+-} 7% and it has been applied to the determination of

  20. Rapid determination of volatile constituents in safflower from Xinjiang and Henan by ultrasonic-assisted solvent extraction and GC-MS

    Institute of Scientific and Technical Information of China (English)

    Ling-Han Jia; Yi Liu; Yu-Zhen Li

    2011-01-01

    The total volatile components were extracted from safflower by ultrasonic-assisted solvent extraction (USE) and their chemical constituents were analyzed by gas chromatographymass spectrometry (GC-MS) to provide scientific basis for the quality control of safflower. Five different solvents (diethyl ether, ethanol, ethyl acetate, dichloromethane and acetone) were used and compared in terms of number of volatile components extracted and the peak areas of these components in TIC. The results showed that USE could be used as an efficient and rapid method for extracting the volatile components from safflower. It also could be found that the number of components in the TIC of ethyl acetate extract was more than that in the TIC of other solvent ones. Meanwhile, the volatile components of safflower from Xinjiang Autonomous Region and Henan Province of China were different in chemical components and relative contents. It could be concluded that both the extraction solvents and geographical origin of safflower are responsible for these differences. The experimental results also indicated that USE/GC-MS is a simple, rapid and effective method to analyze the volatile oil components of safflower.

  1. Determination of Volatile Oil from Zingiber striolatum Diels.by GC-MS%GC-MS法测定阳荷花挥发油的成分

    Institute of Scientific and Technical Information of China (English)

    王军民; 周凡蕊; 陈川云; 水星; 华燕

    2012-01-01

    The volatile oil from Zingiber striolatum Diels flowers were extracted by vapor distillation and the chemical constituents were separated and identified by GC-MS. Then,the relative contents in percentage of compounds were determined by peak area normalization method. The results showed that more than 59 peaks were separated and 55 compounds accounting for 95.54% of the total extracted by steam distillation were identified. The major constituents were identified as olefins 49.08% ,alcohols 22.39% .aldehydes 6.07% .esters 4.72% .oxides 4. 25% .ketones 2.26% ,hydrocarbons 2.19% and benzene derivative 1.81%.%为分析阳荷Zingiber striolatum Diels.花挥发油中的成分,采用水蒸气蒸馏的方法提取阳荷花中的挥发性成分,应用气相色谱-质谱联用法对化学成分进行鉴定,用峰面积归一化法测定各个化合物在挥发油中的相对百分含量.检测出59个化学成分,鉴定了其中55个化学成分总提物的95.54%.其中烯烃类占49.08%,醇类化合物占22.39%,醛类化合物占6.07%,酯类占4.72%,氧化物占4.25%,酮类化合物占2.26%,,还含有少量的烷烃占2.19%,苯的衍生物占1.81%.

  2. Volatile Concentrations and H-Isotope Composition of Unequilibrated Eucrites

    Science.gov (United States)

    Sarafian, Adam R.; Nielsen, Sune G.; Marschall, Horst R.; Gaetani, Glenn A.; Hauri, Erik H.; Righter, Kevin; Berger, Eve L.

    2017-01-01

    Eucrites are among the oldest and best studied asteroidal basalts (1). They represent magmatism that occurred on their parent asteroid, likely 4-Vesta, starting at 4563 Ma and continuing for approx. 30 Myr. Two hypotheses are debated for the genesis of eucrites, a magma ocean model (2), and a mantle partial melting model. In general, volatiles (H, C, F, Cl) have been ignored for eucrites and 4-Vesta, but solubility of wt% levels of H2O are possible at Vestan interior PT conditions. Targeted measurements on samples could aid our understanding considerably. Recent studies have found evidence of volatile elements in eucrites, but quantifying the abundance of volatiles remains problematic (6). Volatile elements have a disproportionately large effect on melt properties and phase stability, relative to their low abundance. The source of volatile elements can be elucidated by examining the hydrogen isotope ratio (D/H), as different H reservoirs have drastically different H isotope compositions. Recent studies of apatite in eucrites have shown that the D/H of 4-Vesta matches that of Earth and carbonaceous chondrites, however, the D/H of apatites may not represent the D/H of a primitive 4-Vesta melt due to the possibility of degassing prior to the crystallization of apatite. Therefore, the D/H of early crystallizing phases must be measured to determine if the D/H of 4-Vesta is equal to that of the Earth and carbonaceous chondrites.

  3. Improved Monkey-King Genetic Algorithm for Solving Large Winner Determination in Combinatorial Auction

    Science.gov (United States)

    Li, Yuzhong

    Using GA solve the winner determination problem (WDP) with large bids and items, run under different distribution, because the search space is large, constraint complex and it may easy to produce infeasible solution, would affect the efficiency and quality of algorithm. This paper present improved MKGA, including three operator: preprocessing, insert bid and exchange recombination, and use Monkey-king elite preservation strategy. Experimental results show that improved MKGA is better than SGA in population size and computation. The problem that traditional branch and bound algorithm hard to solve, improved MKGA can solve and achieve better effect.

  4. Determinants of financial distress in u.s. large bank holding companies

    OpenAIRE

    Zhang, Zhichao; XIE Li; Lu, Xiangyun; zhang, zhuang

    2014-01-01

    With a sample of 354 U.S. large bank holding companies, this paper investigates the determination of financial distress in financial institutions. We find that: (1) the house price index is consistently significant and positively associated with the Distance-to-Default (DD) measure in the U.S. banking market; (2) all the three major banking risk characteristics i.e. non-performing loans, short-term wholesale funding, and the credit-risk indicator are reliable factors behind DD determination; ...

  5. Simultaneous Determination of Large Amount of Uranium and Trace Fission Elements by DRC-ICP-MS

    Institute of Scientific and Technical Information of China (English)

    ZHANG; Lei; LI; Hui-bo; LIU; Fang; HE; Hui; CONG; Hai-feng

    2013-01-01

    Large amount of uranium and trace fission product elements are widely exist in reprocessing process.Since the difference of elements concentration,chemical separation and various dilution ratios should be used to obtain all the values.Inductively coupled plasma mass spectrometry(ICP-MS)can be used to determination of more than 75%elements in the periodic table and meet the needs for analysis of fission

  6. Determining the structure of Higgs couplings at the CERN LargeHadron Collider.

    Science.gov (United States)

    Plehn, Tilman; Rainwater, David; Zeppenfeld, Dieter

    2002-02-01

    Higgs boson production via weak boson fusion at the CERN Large Hadron Collider has the capability to determine the dominant CP nature of a Higgs boson, via the tensor structure of its coupling to weak bosons. This information is contained in the azimuthal angle distribution of the two outgoing forward tagging jets. The technique is independent of both the Higgs boson mass and the observed decay channel.

  7. Emission Rates of Volatile Organic Compounds Released from Newly Produced Household Furniture Products Using a Large-Scale Chamber Testing Method

    Directory of Open Access Journals (Sweden)

    Duy Xuan Ho

    2011-01-01

    Full Text Available The emission rates of volatile organic compounds (VOCs were measured to investigate the emission characteristics of five types of common furniture products using a 5 m3 size chamber at 25°C and 50% humidity. The results indicated that toluene and α-pinene are the most dominant components. The emission rates of individual components decreased constantly through time, approaching the equilibrium emission level. The relative ordering of their emission rates, if assessed in terms of total VOC (TVOC, can be arranged as follows: dining table > sofa > desk chair > bedside table > cabinet. If the emission rates of VOCs are examined between different chemical groups, they can also be arranged in the following order: aromatic (AR > terpenes (TER > carbonyl (CBN > others > paraffin (PR > olefin (HOL > halogenated paraffin (HPR. In addition, if emission strengths are compared between coated and uncoated furniture, there is no significant difference in terms of emission magnitude. Our results indicate that the emission characteristics of VOC are greatly distinguished between different furniture products in terms of relative dominance between different chemicals.

  8. Electrochemical generation of antimony volatile species, stibine, using gold and silver mercury amalgamated cathodes and determination of Sb by flame atomic absorption spectrometry.

    Science.gov (United States)

    Ordoñes, Jessenia; Fernández, Lenys; Romero, Hugo; Carrera, Patricio; Alvarado, José

    2015-08-15

    The electrochemical generation of antimony volatile species (stibine) using Au and Ag mercury amalgamated cathodes is described. Compared with some other cathode materials commonly used for electrochemical hydride generation, performance of the amalgamated cathodes is substantially better in the following aspects: higher interference tolerance, higher erosion resistance and longer useful working time. Using the amalgamated cathodes, it could be shown that interferences from major constituents at high concentrations, especially from transition metals, affecting stibine generation are not as significant as they are using other cathode types in regards to sensitivity and useful working time. Results obtained using the Ag/Hg amalgamated cathode showed a slightly higher sensitivity than the corresponding results obtained using the Au/Hg cathode. The Au/Hg cathode, which to our knowledge has not previously been used to generate stibine, showed considerably longer useful working time than the Ag/Hg one. The optimum catholytes for electrolytic generation of stibine (SbH3) from Sb(III) and Sb(V) using the Au/Hg electrode were aqueous solutions containing 0.5mol L(-1) H2SO4 and 0.5mol L(-1)HCl, respectively. Under optimized conditions, using the Au/Hg cathode and comparing to aqueous standards calibration curves, detection limits (3σ) of 0.027µg L(-1) for Sb(III) and 0.056µg L(-1) for Sb(V), were obtained. To check accuracy a marine sediment reference material (PACS-2, NRC) was analyzed using a method purportedly developed for this task. Good agreement, 95% confidence, was found between the certified and the experimental values for Sb. The proposed method was also applied to the determination of Sb in aqueous solutions of marine sediments samples from Comuna de Bajo Alto Provincia de El Oro-Ecuador. Recoveries of five replicate determinations of these samples were in the range of 98-103% thus showing acceptable accuracy in the analysis of real samples. Copyright © 2015

  9. Biogenic volatile organic compound (BVOC) emissions from forested areas in Turkey: Determination of specific emission rates for thirty-one tree species

    Energy Technology Data Exchange (ETDEWEB)

    Aydin, Yagmur Meltem; Yaman, Baris; Koca, Husnu; Dasdemir, Okan; Kara, Melik; Altiok, Hasan; Dumanoglu, Yetkin; Bayram, Abdurrahman [Department of Environmental Engineering, Faculty of Engineering, Dokuz Eylul University, Tinaztepe Campus, Buca, Izmir (Turkey); Tolunay, Doganay [Department of Soil Science and Ecology, Faculty of Forestry, Istanbul University, Bahcekoy, Istanbul (Turkey); Odabasi, Mustafa [Department of Environmental Engineering, Faculty of Engineering, Dokuz Eylul University, Tinaztepe Campus, Buca, Izmir (Turkey); Elbir, Tolga, E-mail: tolga.elbir@deu.edu.tr [Department of Environmental Engineering, Faculty of Engineering, Dokuz Eylul University, Tinaztepe Campus, Buca, Izmir (Turkey)

    2014-08-15

    Normalized biogenic volatile organic compound (BVOC) emission rates for thirty one tree species that cover the 98% of national forested areas in Turkey were determined. Field samplings were performed at fourteen different forested areas in Turkey using a specific dynamic enclosure system. The selected branches of tree species were enclosed in a chamber consisted of a transparent Nalofan bag. The air-flows were sampled from both inlet and outlet of the chamber by Tenax-filled sorbent tubes during photosynthesis of trees under the presence of sunlight. Several environmental parameters (temperature, humidity, photosynthetically active radiation-PAR, and CO{sub 2}) were continuously monitored inside and outside the enclosure chamber during the samplings. Collected samples were analyzed using a gas chromatography mass spectrometry (GC/MS) system equipped with a thermal desorber (TD). Sixty five BVOCs classified in five major groups (isoprene, monoterpenes, sesquiterpenes, oxygenated sesquiterpenes, and other oxygenated compounds) were analyzed. Emission rates were determined by normalization to standard conditions (1000 μmol/m{sup 2} s PAR and 30 °C temperature for isoprene and 30 °C temperature for the remaining compounds). In agreement with the literature, isoprene was mostly emitted by broad-leaved trees while coniferous species mainly emitted monoterpenes. Several tree species such as Sweet Chestnut, Silver Lime, and European Alder had higher monoterpene emissions although they are broad-leaved species. High isoprene emissions were also observed for a few coniferous species such as Nordmann Fir and Oriental Spruce. The highest normalized total BVOC emission rate of 27.1 μg/g h was observed for Oriental Plane while South European Flowering Ash was the weakest BVOC emitter with a total normalized emission rate of 0.031 μg/g h. Monoterpene emissions of broad-leaved species mainly consisted of sabinene, limonene and trans-beta-ocimene, while alpha-pinene, beta

  10. Quantifying the volatility of organic aerosol in the southeastern US

    Science.gov (United States)

    Saha, Provat K.; Khlystov, Andrey; Yahya, Khairunnisa; Zhang, Yang; Xu, Lu; Ng, Nga L.; Grieshop, Andrew P.

    2017-01-01

    The volatility of organic aerosols (OA) has emerged as a property of primary importance in understanding their atmospheric life cycle, and thus abundance and transport. However, quantitative estimates of the thermodynamic (volatility, water solubility) and kinetic parameters dictating ambient-OA gas-particle partitioning, such as saturation concentrations (C∗), enthalpy of evaporation (ΔHvap), and evaporation coefficient (γe), are highly uncertain. Here, we present measurements of ambient-OA volatility at two sites in the southeastern US, one at a rural setting in Alabama dominated by biogenic volatile organic compounds (BVOCs) as part of the Southern Oxidant and Aerosol Study (SOAS) in June-July 2013, and another at a more anthropogenically influenced urban location in North Carolina during October-November 2013. These measurements applied a dual-thermodenuder (TD) system, in which temperature and residence times are varied in parallel to constrain equilibrium and kinetic aerosol volatility properties. Gas-particle partitioning parameters were determined via evaporation kinetic model fits to the dual-TD observations. OA volatility parameter values derived from both datasets were similar despite the fact that measurements were collected in distinct settings and seasons. The OA volatility distributions also did not vary dramatically over the campaign period or strongly correlate with OA components identified via positive matrix factorization of aerosol mass spectrometer data. A large portion (40-70 %) of measured ambient OA at both sites was composed of very-low-volatility organics (C∗ ≤ 0.1 µg m-3). An effective ΔHvap of bulk OA of ˜ 80-100 kJ mol-1 and a γe value of ˜ 0.5 best describe the evaporation observed in the TDs. This range of ΔHvap values is substantially higher than that typically assumed for simulating OA in atmospheric models (30-40 kJ mol-1). TD data indicate that γe is on the order of 0.1 to 0.5, indicating that repartitioning

  11. Headspace-Solid-Phase Microextraction-Gas Chromatography as Analytical Methodology for the Determination of Volatiles in Wild Mushrooms and Evaluation of Modifications Occurring during Storage

    Directory of Open Access Journals (Sweden)

    Rosaria Costa

    2015-01-01

    Full Text Available Mushrooms are sources of food, medicines, and agricultural means. Not much is reported in the literature about wild species of the Mediterranean flora, although many of them are traditionally collected for human consumption. The knowledge of their chemical constituents could represent a valid tool for both taxonomic and physiological characterizations. In this work, a headspace-solid-phase microextraction (HS-SPME method coupled with GC-MS and GC-FID was developed to evaluate the volatile profiles of ten wild mushroom species collected in South Italy. In addition, in order to evaluate the potential of this analytical methodology for true quantitation of volatiles, samples of the cultivated species Agaricus bisporus were analyzed. The choice of this mushroom was dictated by its ease of availability in the food market, due to the consistent amounts required for SPME method development. For calibration of the main volatile compounds, the standard addition method was chosen. Finally, the assessed volatile composition of A. bisporus was monitored in order to evaluate compositional changes occurring during storage, which represents a relevant issue for such a wide consumption edible product.

  12. Determination of volatile organic compounds in the dried leaves of Salvia species by solid-phase microextraction coupled to gas chromatography mass spectrometry.

    Science.gov (United States)

    Cozzolino, Rosaria; Ramezani, Sadrollah; Martignetti, Antonella; Mari, Angela; Piacente, Sonia; De Giulio, Beatrice

    2016-01-01

    Salvia spp. are used throughout the world both for food and pharmaceutical purposes. In this study, a method involving headspace solid-phase microextraction combined with gas chromatography-mass spectrometry was developed, to establish the volatiles profile of dried leaves of four Iranian Salvia spp.: Salvia officinalis L., Salvia leriifolia Benth, Salvia macrosiphon Boiss. and two ecotypes of Salvia reuterana Boiss. A total of 95 volatiles were identified from the dried leaves of the five selected samples. Specifically, α-thujone was the main component of S. officinalis L. and S. macrosiphon Boiss. (34.40 and 17.84%, respectively) dried leaves, S. leriifolia Benth was dominated by β-pinene (27.03%), whereas α-terpinene was the major constituent of the two ecotypes of S. reuterana Boiss. (21.67 and 13.84%, respectively). These results suggested that the proposed method can be considered as a reliable technique for isolating volatiles from aromatic plants, and for plant differentiation based on the volatile metabolomic profile.

  13. 公司特质波动决定因素研究--信息效率还是噪音交易?%The Determinants of Idiosyncratic Volatility:Firm-specific Information or Occasional Frenzy?

    Institute of Scientific and Technical Information of China (English)

    陈浪南; 熊伟

    2014-01-01

    We investigate the determinants of the idiosyncratic volatility by utilizing the regression and employing the daily data from Shanghai Stock Exchange from 1 997 to 2010. First of all,we measure the idiosyncratic volatility by utilizing the nonparametric method of Campbell,Lettau,Malkiel and Xu (or CLMX,2001)and the parametric method of Malk-iel and Xu (2003)and Ang,Hodrick,Xing and Zhang (2009).The nonparametric method is based on the fact that the weighted average of all betas in the stock market with respect to the market factor is equal to 1.Thus,we can derive a weighted average volatility at the market level.And then,we calculate the stock return volatilities each month with daily data and di-vide the total volatility into three parts:market volatility,industry volatility and firm-specific volatility.The parametric method is based on the residuals of the CAPM model.We regress the daily excess returns of stock i against the daily market returns and use the variance of the daily regression residuals each month as the idiosyncratic volatility of stock i in that month. Secondly,we derive an empirical model to test the determinants of the idiosyncratic vola-tility.We examine the determinants of idiosyncratic volatility by incorporating the cross-term of idiosyncratic volatility,current unexpected earnings,lagged unexpected earnings and fu-ture unexpected earnings into the regression against excessive stock return. ri,t =αi +∑1τ=-1 [λτΔEi,t+τ]+α1 IVi,t +∑1τ=1 [βτIVi,tΔEi,t+τ]+α2 asseti,t +α3 ri,t+1 +ξi,t where,ri,t is the excess stock return,IVi,t is the idiosyncratic volatility of firm i in year t,ΔEi,t+τ is the unexpected earnings,which is the difference between the current earnings and the earnings last year divided by the size of the firm.We use the stock return next year as a control variable to reduce the measure errors in the unexpected earnings (Collins et al., 1 994).asseti,t is the firm size,which is the log value of the outstanding

  14. Presence and significant determinants of cognitive impairment in a large sample of patients with multiple sclerosis.

    Directory of Open Access Journals (Sweden)

    Martina Borghi

    Full Text Available OBJECTIVES: To investigate the presence and the nature of cognitive impairment in a large sample of patients with Multiple Sclerosis (MS, and to identify clinical and demographic determinants of cognitive impairment in MS. METHODS: 303 patients with MS and 279 healthy controls were administered the Brief Repeatable Battery of Neuropsychological tests (BRB-N; measures of pre-morbid verbal competence and neuropsychiatric measures were also administered. RESULTS: Patients and healthy controls were matched for age, gender, education and pre-morbid verbal Intelligence Quotient. Patients presenting with cognitive impairment were 108/303 (35.6%. In the overall group of participants, the significant predictors of the most sensitive BRB-N scores were: presence of MS, age, education, and Vocabulary. The significant predictors when considering MS patients only were: course of MS, age, education, vocabulary, and depression. Using logistic regression analyses, significant determinants of the presence of cognitive impairment in relapsing-remitting MS patients were: duration of illness (OR = 1.053, 95% CI = 1.010-1.097, p = 0.015, Expanded Disability Status Scale score (OR = 1.247, 95% CI = 1.024-1.517, p = 0.028, and vocabulary (OR = 0.960, 95% CI = 0.936-0.984, p = 0.001, while in the smaller group of progressive MS patients these predictors did not play a significant role in determining the cognitive outcome. CONCLUSIONS: Our results corroborate the evidence about the presence and the nature of cognitive impairment in a large sample of patients with MS. Furthermore, our findings identify significant clinical and demographic determinants of cognitive impairment in a large sample of MS patients for the first time. Implications for further research and clinical practice were discussed.

  15. Volatile Organic Compounds (VOCs)

    Science.gov (United States)

    ... Contact Us Share Volatile Organic Compounds' Impact on Indoor Air Quality On this page: Introduction Sources Health Effects Levels in Homes Steps to Reduce Exposure Standards or Guidelines Additional Resources Introduction Volatile organic compounds ( ...

  16. Spatial dynamics of large-scale, multistage crab (Callinectes sapidus) dispersal: Determinants and consequences for recruitment

    Science.gov (United States)

    Etherington, L.L.; Eggleston, D.B.

    2003-01-01

    We assessed determinants and consequences of multistage dispersal on spatial recruitment of the blue crab, Callinectes sapidus, within the Croatan, Albemarle, Pamlico Estuarine System (CAPES), North Carolina, U.S.A. Large-scale sampling of early juvenile crabs over 4 years indicated that spatial abundance patterns were size-dependent and resulted from primary post-larval dispersal (pre-settlement) and secondary juvenile dispersal (early post-settlement). In general, primary dispersal led to high abundances within more seaward habitats, whereas secondary dispersal (which was relatively consistent) expanded the distribution of juveniles, potentially increasing the estuarine nursery capacity. There were strong relationships between juvenile crab density and specific wind characteristics; however, these patterns were spatially explicit. Various physical processes (e.g., seasonal wind events, timing and magnitude of tropical cyclones) interacted to influence dispersal during multiple stages and determined crab recruitment patterns. Our results suggest that the nursery value of different habitats is highly dependent on the dispersal potential (primary and secondary dispersal) to and from these areas, which is largely determined by the relative position of habitats within the estuarine landscape.

  17. Use of Direct Dynamics Simulations to Determine Unimolecular Reaction Paths and Arrhenius Parameters for Large Molecules.

    Science.gov (United States)

    Yang, Li; Sun, Rui; Hase, William L

    2011-11-08

    In a previous study (J. Chem. Phys.2008, 129, 094701) it was shown that for a large molecule, with a total energy much greater than its barrier for decomposition and whose vibrational modes are harmonic oscillators, the expressions for the classical Rice-Ramsperger-Kassel-Marcus (RRKM) (i.e., RRK) and classical transition-state theory (TST) rate constants become equivalent. Using this relationship, a molecule's unimolecular rate constants versus temperature may be determined from chemical dynamics simulations of microcanonical ensembles for the molecule at different total energies. The simulation identifies the molecule's unimolecular pathways and their Arrhenius parameters. In the work presented here, this approach is used to study the thermal decomposition of CH3-NH-CH═CH-CH3, an important constituent in the polymer of cross-linked epoxy resins. Direct dynamics simulations, at the MP2/6-31+G* level of theory, were used to investigate the decomposition of microcanonical ensembles for this molecule. The Arrhenius A and Ea parameters determined from the direct dynamics simulation are in very good agreement with the TST Arrhenius parameters for the MP2/6-31+G* potential energy surface. The simulation method applied here may be particularly useful for large molecules with a multitude of decomposition pathways and whose transition states may be difficult to determine and have structures that are not readily obvious.

  18. Large-scale length that could determine the mean rate of energy dissipation in turbulence

    CERN Document Server

    Mouri, H; Kawashima, Y; Hashimoto, K

    2012-01-01

    The mean rate of energy dissipation in turbulence is traditionally assumed to scale with parameters of the energy-containing large scales, i.e., the root-mean-square fluctuation of the longitudinal velocity u and its correlation length L(u). However, the resultant scaling coefficient C(u) is known to depend on the large-scale configuration of the flow. We define the correlation length L(u2) of the local energy u2, study the scaling coefficient C(u2) with experimental data of several flows, and find a possibility that C(u2) does not depend on the flow configuration. Not L(u) but rather L(u2) could scale with the typical size of the energy-containing eddies, so that L(u2) determines the mean rate at which the energy is transferred from those eddies to the smaller eddies and is eventually dissipated into heat.

  19. Optimization of the HS-SPME-GC/MS technique for determining volatile compounds in red wines made from Isabel grapes (Vitis labrusca

    Directory of Open Access Journals (Sweden)

    Narciza Maria de Oliveira ARCANJO

    2015-01-01

    Full Text Available AbstractBrazilian wine production is characterized by Vitis labrusca grape varieties, especially the economically important Isabel cultivar, with over 80% of its production destined for table wine production. The objective of this study was to optimize and validate the conditions for extracting volatile compounds from wine with the solid-phase microextraction technique, using the response surface method. Based on the response surface analysis, it can be concluded that the central point values maximize the process of extracting volatile compounds from wine, i.e., an equilibrium time of 15 minutes, an extraction time of 35 minutes, and an extraction temperature of 30 °C. Esters were the most numerous compounds found under these extraction conditions, indicating that wines made from Isabel cultivar grapes are characterized by compounds that confer a fruity aroma; this finding corroborates the scientific literature.

  20. Determination of volatile organic compounds, catechins, caffeine and theanine in Jukro tea at three growth stages by chromatographic and spectrometric methods.

    Science.gov (United States)

    Jeon, Dong Bok; Hong, Young Shin; Lee, Ga Hyun; Park, Yu Min; Lee, Cheong Mi; Nho, Eun Yeong; Choi, Ji Yeon; Jamila, Nargis; Khan, Naeem; Kim, Kyong Su

    2017-03-15

    Tea contains characteristic volatile organic compounds, polyphenols, caffeine and catechins, and is therefore among the most widely consumed beverages all over the world. In this study, fresh Jukro tea leaves collected from Damyang-gun (Jeollanam-do) at 40, 60 and 90day growth stages, were semi-fermented. The volatile organic compounds (VOCs) were extracted by simultaneous distillation-solvent extraction (SDE) and analyzed by gas chromatography/mass spectrometry (GC/MS). Catechins, caffeine and theanine were analyzed by high performance liquid chromatography (HPLC). A total of 159 VOCs were identified in the analyzed Jukro tea leaves. Comparatively, the increase in the concentrations of VOCs was high in 60day leaves. The content of catechins increased along the three growth stages, whereas caffeine, compared to 90day leaves, was higher for 40 and 60day leaves. Based on the results, the 60day leaves were found to be the most suitable and useful for making semi-fermented Jukro tea.

  1. Does Energy Consumption Volatility Affect Real GDP Volatility? An Empirical Analysis for the UK

    OpenAIRE

    Abdul Rashid; Ozge Kandemir Kocaaslan

    2013-01-01

    This paper empirically examines the relation between energy consumption volatility and unpredictable variations in real gross domestic product (GDP) in the UK. Estimating the Markov switching ARCH model we find a significant regime switching in the behavior of both energy consumption and GDP volatility. The results from the Markov regime-switching model show that the variability of energy consumption has a significant role to play in determining the behavior of GDP volatilities. Moreover, the...

  2. ActiveSeismoPick3D - automatic first arrival determination for large active seismic arrays

    Science.gov (United States)

    Paffrath, Marcel; Küperkoch, Ludger; Wehling-Benatelli, Sebastian; Friederich, Wolfgang

    2016-04-01

    We developed a tool for automatic determination of first arrivals in active seismic data based on an approach, that utilises higher order statistics (HOS) and the Akaike information criterion (AIC), commonly used in seismology, but not in active seismics. Automatic picking is highly desirable in active seismics as the number of data provided by large seismic arrays rapidly exceeds of what an analyst can evaluate in a reasonable amount of time. To bring the functionality of automatic phase picking into the context of active data, the software package ActiveSeismoPick3D was developed in Python. It uses a modified algorithm for the determination of first arrivals which searches for the HOS maximum in unfiltered data. Additionally, it offers tools for manual quality control and postprocessing, e.g. various visualisation and repicking functionalities. For flexibility, the tool also includes methods for the preparation of geometry information of large seismic arrays and improved interfaces to the Fast Marching Tomography Package (FMTOMO), which can be used for the prediction of travel times and inversion for subsurface properties. Output files are generated in the VTK format, allowing the 3D visualization of e.g. the inversion results. As a test case, a data set consisting of 9216 traces from 64 shots was gathered, recorded at 144 receivers deployed in a regular 2D array of a size of 100 x 100 m. ActiveSeismoPick3D automatically checks the determined first arrivals by a dynamic signal to noise ratio threshold. From the data a 3D model of the subsurface was generated using the export functionality of the package and FMTOMO.

  3. Determining suitability of Large Aperture Scintillometer for validating remote sensing based evapotranspiration maps

    Science.gov (United States)

    Paul, G.; Gowda, P. H.; Howell, T. A.; Basu, S.; Colaizzi, P. D.; Marek, T.

    2013-12-01

    Scintillation method is a relatively new technique for measuring the sensible heat and water fluxes over land surfaces. Path integrating capabilities of scintillometer over heterogeneous landscapes make it a potential tool for comparing the energy fluxes derived from remote sensing based energy balance algorithms. For this reason, scintillometer-derived evapotranspiration (ET) fluxes are being used to evaluate remote sensing based energy balance algorithms for their ability to estimate ET fluxes. However, LAS' (Large Aperture Scintillometer) ability to derive ET fluxes is not thoroughly tested. The objective of this study was to evaluate LAS- and Surface Energy Balance System (SEBS)-derived fluxes against lysimetric data to determine LAS' suitability for validating remote sensing based evapotranspiration (ET) maps. The study was conducted during the Bushland Evapotranspiration and Agricultural Remote sensing EXperiment - 2008 (BEAREX-08) at the USDA-ARS Conservation and Production Research Laboratory (CPRL), Bushland, Texas. SEBS was coded in a GIS environment to retrieve ET fluxes from the high resolution imageries acquired using airborne multispectral sensors. The CPRL has four large weighing lysimeters (3 m long x 3 m wide x 2.4 m deep), each located in the middle of approximately 5 ha fields, arranged in a block pattern. The two lysimeter fields located on the east (NE and SE) were managed under irrigated conditions, and the other two lysimeters on the west (NW and SW) were under dryland management. Each lysimeter field was equipped with an automated weather station that provided measurements for net radiation (Rn), Ts, soil heat flux (Go), Ta, relative humidity, and wind speed. During BEAREX08, the NE and SE fields were planted to cotton on May 21, and the NW and SW dryland lysimeters fields were planted to cotton on June 5. One LAS each was deployed across two large dryland lysimeter fields (NW and SW) and two large irrigated lysimeter fields (NE and SE). The

  4. Large-Scale Simulation of Multi-Asset Ising Financial Markets

    Science.gov (United States)

    Takaishi, Tetsuya

    2017-03-01

    We perform a large-scale simulation of an Ising-based financial market model that includes 300 asset time series. The financial system simulated by the model shows a fat-tailed return distribution and volatility clustering and exhibits unstable periods indicated by the volatility index measured as the average of absolute-returns. Moreover, we determine that the cumulative risk fraction, which measures the system risk, changes at high volatility periods. We also calculate the inverse participation ratio (IPR) and its higher-power version, IPR6, from the absolute-return cross-correlation matrix. Finally, we show that the IPR and IPR6 also change at high volatility periods.

  5. 苏云金芽胞杆菌挥发性物质的测定%Determination of Bacillus thuringiensis volatile substances

    Institute of Scientific and Technical Information of China (English)

    郑梅霞; 潘志针; 刘波; 陈峥; 车建美; 唐建阳; 朱育菁; 陈梅春

    2014-01-01

    目的:分析、鉴定苏云金芽胞杆菌(Bacillus thuringiensis, Bt)的挥发性成分。方法采用顶空固相微萃取技术(HS-SPME)对 Bt 的挥发性成分进行捕集,再通过气相色谱-质谱联用(GC-MS)技术对挥发性成分进行鉴定。以本实验室分离的高效苏云金芽胞杆菌 FJAT-12菌株为实验菌株,探索 Bt 菌株的不同培养方式、不同固相微萃取吸附方式及不同萃取头的选择对挥发性成分鉴定结果的影响,确定 Bt 菌株挥发性物质测定的最优方法。结果采用NA液体培养基培养,选择水浴至气-液平衡再吸附的吸附方式,采用65µm PDMS/DVB萃取头的萃取效果最佳。Bt菌株的挥发性成分主要为6-甲基-2-庚酮、2,4-二氨基甲苯、苯甲醇、2,3-二乙基-5-甲基吡嗪、2-甲基萘、2,3-Dimethyl-5-isopentylpyrazine、十四烷、正十二烷、2-甲硫基苯并噻唑。结论 HS-SPME/GC-MS效果好,方法实用,便于操作,适用于对Bt挥发性成分进行分析,从而为食品安全评估提供理论依据。%Objective To analyze and identify the volatile substances of Bacillus thuringiensis. Methods The volatile constituents of Bacillus thuringiensis were captured by headspace solid phase micro-extraction technology (HS-SPME) and identified by gas chromatography-mass spectrometry (GC-MS) tech-nology. The optimal method was used to analyze the volatile constituents of Bacillus thuringiensis FJAT-12, which was a high efficient strain separated by our lab, investigated from the culture way, adsorption pattern and fibers type. Results Bacillus thuringiensis FJAT-12 was better cultured by NA liquid medium, and volatile vial was maintained in a water bath at 50 ℃ for equilibrating (180 min) and then extracted by 65 µm PDMS/DVB fibers for 60 min. The mainly volatile constituents of Bt were 6-methyl-2-Heptanone, 4-methyl-1,3-Benzenediamine, Benzyl Alcohol, 3,5-diethyl-2-methyl-Pyrazine, 2-methyl-Naphthalene, 2,3-Dimethyl-5-isopentylpyrazine

  6. Large-scale determinants of intestinal schistosomiasis and intermediate host snail distribution across Africa

    DEFF Research Database (Denmark)

    Stensgaard, Anna-Sofie; Utzinger, Jürg; Vounatsou, Penelope

    2013-01-01

    to climate change. Here, we combine a growing degree day model for Schistosoma mansoni with species distribution models for the intermediate host snail (Biomphalaria spp.) to investigate large-scale environmental determinants of the distribution of the African S. mansoni-Biomphalaria system and potential...... impacts of climatic changes. Snail species distribution models included several combinations of climatic and habitat-related predictors; the latter divided into "natural" and "human-impacted" habitat variables to measure anthropogenic influence. The predictive performance of the combined snail......-parasite model was evaluated against a comprehensive compilation of historical S. mansoni parasitological survey records, and then examined for two climate change scenarios of increasing severity for 2080. Future projections indicate that while the potential S. mansoni transmission area expands, the snail ranges...

  7. The Friction Force Determination of Large-Sized Composite Rods in Pultrusion

    Science.gov (United States)

    Grigoriev, S. N.; Krasnovskii, A. N.; Kazakov, I. A.

    2014-08-01

    Nowadays, the simple pull-force models of pultrusion process are not suitable for large sized rods because they are not considered a chemical shrinkage and thermal expansion acting in cured material inside the die. But the pulling force of the resin-impregnated fibers as they travels through the heated die is essential factor in the pultrusion process. In order to minimize the number of trial-and-error experiments a new mathematical approach to determine the frictional force is presented. The governing equations of the model are stated in general terms and various simplifications are implemented in order to obtain solutions without extensive numerical efforts. The influence of different pultrusion parameters on the frictional force value is investigated. The results obtained by the model can establish a foundation by which process control parameters are selected to achieve an appropriate pull-force and can be used for optimization pultrusion process.

  8. DETERMINATION OF THERMODYNAMIC AND KINETIC PARAMETERS OF LARGE SCALE CHROMATOGRAPHIC SEPARATION OF SUGAR AND REDUCING SUGAR

    Institute of Scientific and Technical Information of China (English)

    LiZhong; ShuWenli; 等

    1996-01-01

    The parameter identification model of large scale chromatography separation process is proposed.The phase equilibrium constants and lumped mass transfer coefficients of sugar and reducing sugar adsorption on D1,D2 and D3 resins as well as the axial dispersion coefficients of the fluid through packed columns are determined by means of the pulse-response experiment technique with an inert substance as a tracer and the chromatography measuring technique.The elution curve calculated from these parameters is good agreement with the experimental elution curve.The sensitivity analysis of these parameters is carried out ,and the result shows that the elution curves of chromatography separation are more sensitive to the variations of the phase equilibrium relationship than to the variation of the axial dispersion as well as the lumped mass transfer coefficients.

  9. Determination of 137Cs in large volume seawater using Cu-hexacyanoferrate cartridge filters

    Science.gov (United States)

    Visetpotjanakit, S.; Tumnoi, Y.

    2017-06-01

    A simple method to determine 137Cs in seawater has been developed based on the use of a Cu-hexacyanoferrate scavenger. The Cu-hexacyanoferrate supported on cotton wound cartridge filter was used to absorb 137Cs from seawater by passing large volumes over the cartridge filters with flowrate of 240 L hr-1. Results from the Cu-hexacyanoferrate method were proved acceptable for accuracy with bias below ± 20 % i.e. - 9.16 to + 18.55 % when compared with the traditional ammonium molybdophosphate pre-concentration method. This developed method is cost-effective and less time consuming. In addition it can be easily performed at sampling fields.

  10. Determine the galaxy bias factors on large scales using bispectrum method

    CERN Document Server

    Guo, Hong

    2009-01-01

    We study whether the bias factors of galaxies can be unbiasedly recovered from their power spectra and bispectra. We use a set of numerical N-body simulations and construct large mock galaxy catalogs based upon the semi-analytical model of Croton et al. (2006). We measure the reduced bispectra for galaxies of different luminosity, and determine the linear and first nonlinear bias factors from their bispectra. We find that on large scales down to that of the wavenumber k=0.1h/Mpc, the bias factors b1 and b2 are nearly constant, and b1 obtained with the bispectrum method agrees very well with the expected value. The nonlinear bias factor b2 is negative, except for the most luminous galaxies with M<-23 which have a positive b2. The behavior of b2 of galaxies is consistent with the b2 mass dependence of their host halos. We show that it is essential to have an accurate estimation of the dark matter bispectrum in order to have an unbiased measurement of b1 and b2. We also test the analytical approach of incorpo...

  11. Anisotropic diffusion of volatile pollutants at air-water interface

    Institute of Scientific and Technical Information of China (English)

    Li-ping CHEN; Jing-tao CHENG; Guang-fa DENG

    2013-01-01

    The volatile pollutants that spill into natural waters cause water pollution. Air pollution arises from the water pollution because of volatilization. Mass exchange caused by turbulent fluctuation is stronger in the direction normal to the air-water interface than in other directions due to the large density difference between water and air. In order to explore the characteristics of anisotropic diffusion of the volatile pollutants at the air-water interface, the relationship between velocity gradient and mass transfer rate was established to calculate the turbulent mass diffusivity. A second-order accurate smooth transition differencing scheme (STDS) was proposed to guarantee the boundedness for the flow and mass transfer at the air-water interface. Simulations and experiments were performed to study the trichloroethylene (C2HCl3) release. By comparing the anisotropic coupling diffusion model, isotropic coupling diffusion model, and non-coupling diffusion model, the features of the transport of volatile pollutants at the air-water interface were determined. The results show that the anisotropic coupling diffusion model is more accurate than the isotropic coupling diffusion model and non-coupling diffusion model. Mass transfer significantly increases with the increase of the air-water relative velocity at a low relative velocity. However, at a higher relative velocity, an increase in the relative velocity has no effect on mass transfer.

  12. Anisotropic diffusion of volatile pollutants at air-water interface

    Directory of Open Access Journals (Sweden)

    Li-ping CHEN

    2013-04-01

    Full Text Available The volatile pollutants that spill into natural waters cause water pollution. Air pollution arises from the water pollution because of volatilization. Mass exchange caused by turbulent fluctuation is stronger in the direction normal to the air-water interface than in other directions due to the large density difference between water and air. In order to explore the characteristics of anisotropic diffusion of the volatile pollutants at the air-water interface, the relationship between velocity gradient and mass transfer rate was established to calculate the turbulent mass diffusivity. A second-order accurate smooth transition differencing scheme (STDS was proposed to guarantee the boundedness for the flow and mass transfer at the air-water interface. Simulations and experiments were performed to study the trichloroethylene (C2HCl3 release. By comparing the anisotropic coupling diffusion model, isotropic coupling diffusion model, and non-coupling diffusion model, the features of the transport of volatile pollutants at the air-water interface were determined. The results show that the anisotropic coupling diffusion model is more accurate than the isotropic coupling diffusion model and non-coupling diffusion model. Mass transfer significantly increases with the increase of the air-water relative velocity at a low relative velocity. However, at a higher relative velocity, an increase in the relative velocity has no effect on mass transfer.

  13. Determination of volatile halohydrocarbons in drinking water by capillary column gas chromatography%毛细管柱气相色谱法测定生活饮用水中挥发性卤代烃

    Institute of Scientific and Technical Information of China (English)

    董玉英; 张瑞雨; 欧利华

    2013-01-01

    Objective: To establish a method for determination of seven volatile halohydrocarbons in drinking water. Methods: The seven volatile halohydrocarbons (chlorofrom, tetrachloromethane, trichloroethylene, bromodi-chloromethane, tetrachloroethylene, dibromochloromethane, bromoform) in drinking water were determined by head-space Gas Chromatography with DB - 624 capillary column. Results: Under the optimal experimental conditions, the recoveries of the seven volatile halohydrocarbons were in the range of 92.5% -102%, the relative standard deviation was between 1.20% ~4.61%, and the determination limit was between 0.01 μg/L ~ 1.00 μg/L. Conclusion: The developed methjod is sensitive, simple, rapid and accurate, and seven volatile halohydrocarbons in drinking water can be determined simultaneously.%目的:建立一种快速、准确测定生活饮用水中7种挥发性卤代烃的方法.方法:采用DB-624毛细管柱、顶空气相色谱法测定生活饮用水中三氯甲烷、四氯化碳、三氯乙烯、二氯一溴甲烷、四氯乙烯、一氯二溴甲烷及三溴甲烷.结果:在所选择的实验条件下,7种挥发性卤代烃的平均回收率在92.5%~102%之间,相对标准偏差(RSD)为1.20% ~4.61%,检出限为0.01 μg/L ~1.00 μg/L.结论:所建立的分析方法灵敏、简便、快速、准确,可同时测定生活饮用水中的7种挥发性卤代烃.

  14. Determination of the efficiency of a detector in gamma spectrometry of large-volume samples

    CERN Document Server

    Tertyshnik, E G

    2012-01-01

    The experimental - calculated method is proposed to determine the full energy peak efficiency (FEPE) of detectors {\\epsilon}(E) in case a measurement of the large-volume samples. Water is used as standard absorber in which the linear attenuation coefficients for photons {\\mu}0 (E) is well known. The value {\\mu} (E) in sample material (matrix of the sample) is determined experimentally by means of spectrometer. The formulas are given for calculation of the ratio {\\epsilon}(E)/ {\\epsilon}0(E), where {\\epsilon}0(E) is FEPE of the detector for photons those are arising in the container filled with water (it is found by adding in the container of the Reference radioactive solutions). To prove the validity of the method ethanol (density 0,8 g/cm3) and water solutions of salts (density 1,2 and 1,5 g/cm3) were used for simulation of the samples with different attenuation coefficients. Standard deviation between experimental and calculated efficiencies has been about 5 %.

  15. Determination of filtration efficiency of filter on volatile carbonyl compounds in cigarette mainstream smoke%滤嘴对卷烟主流烟气中挥发性羰基化合物截留效率的测定

    Institute of Scientific and Technical Information of China (English)

    王丽苹

    2015-01-01

    本文采用HPLC和GC分别对国内市场占有率较高的18种牌号卷烟主流烟气及其滤嘴中挥发性羰基化合物的含量进行了测定,并对滤嘴截留挥发性羰基化合物效率和机制进行了探讨。结果表明:卷烟主流烟气中挥发性羰基化合物含量高低的顺序是乙醛、丙酮、甲醛、丙稀醛、巴豆醛、丁酮和丁醛;滤嘴中挥发性羰基化合物含量高低的顺序是甲醛、丁酮、巴豆醛、丁醛、丙稀醛、丙酮和乙醛;滤嘴对羰基化合物截留效率高低的顺序是巴豆醛、丁酮、甲醛、丁醛、丙烯醛、丙酮和乙醛。二醋酸纤维丝束对挥发性羰基化合物的截留效率较聚丙烯丝束好。%HPLC and GC were respectively applied to determine the volatile carbonyl compounds in cigarette mainstream smoke and filters of 18 cigarettes which are popularly smoked by Chinese,and the filtration efficiency of filter and filtration mechanism were discussed. The results shows that the order of amount of volatile carbonyl compound in cigarette mainstream smoke is acetaldehyde, acetone,formaldehyde,acrolein,crontonaldehyde,methyl ethyl ketone and butyraldehyde;the order of amount of volatile carbonyl compound retained by filter is formaldehyde,methyl ethyl ketone,crontonaldehyde,butyraldehyde,acrolein,acetone and acetalde-hyde;the order of filtration efficiency of filter on volatile carbonyl compounds is crontonaldehyde, methyl ethyl ketone, formalde-hyde,butyraldehyde,acrolein,acetone and acetaldehyde. Acetate filter is better than the polypropylene filter in the filtration efficien-cy on the volatile carbonyl compounds in cigarette mainstream smoke.

  16. Root–shoot allometry of tropical forest trees determined in a large-scale aeroponic system

    Science.gov (United States)

    Eshel, Amram; Grünzweig, José M.

    2013-01-01

    Background and Aims This study is a first step in a multi-stage project aimed at determining allometric relationships among the tropical tree organs, and carbon fluxes between the various tree parts and their environment. Information on canopy–root interrelationships is needed to improve understanding of above- and below-ground processes and for modelling of the regional and global carbon cycle. Allometric relationships between the sizes of different plant parts will be determined. Methods Two tropical forest species were used in this study: Ceiba pentandra (kapok), a fast-growing tree native to South and Central America and to Western Africa, and Khaya anthotheca (African mahogany), a slower-growing tree native to Central and Eastern Africa. Growth and allometric parameters of 12-month-old saplings grown in a large-scale aeroponic system and in 50-L soil containers were compared. The main advantage of growing plants in aeroponics is that their root systems are fully accessible throughout the plant life, and can be fully recovered for harvesting. Key Results The expected differences in shoot and root size between the fast-growing C. pentandra and the slower-growing K. anthotheca were evident in both growth systems. Roots were recovered from the aeroponically grown saplings only, and their distribution among various diameter classes followed the patterns expected from the literature. Stem, branch and leaf allometric parameters were similar for saplings of each species grown in the two systems. Conclusions The aeroponic tree growth system can be utilized for determining the basic allometric relationships between root and shoot components of these trees, and hence can be used to study carbon allocation and fluxes of whole above- and below-ground tree parts. PMID:23250916

  17. Determination of volatile compounds in cider apple juices using a covalently bonded ionic liquid coating as the stationary phase in gas chromatography.

    Science.gov (United States)

    Pello-Palma, Jairo; González-Álvarez, Jaime; Gutiérrez-Álvarez, María Dolores; Dapena de la Fuente, Enrique; Mangas-Alonso, Juan José; Méndez-Sánchez, Daniel; Gotor-Fernández, Vicente; Arias-Abrodo, Pilar

    2017-04-01

    A chromatographic method for the separation of volatile compounds in Asturian cider apple juices has been developed. For this separation purpose, a monocationic imidazolium-based ionic liquid bearing a reactive terminal iodine atom was synthesized by a quaternization-anion exchange chemical sequence. Next, the gas chromatography (GC) stationary phase was prepared by covalently linking the imidazolium monolith to the reactive silanol groups of the inner capillary wall at 70 °C. This coated GC column exhibited good thermal stability (290 °C), as well as good efficiency (2000 plates/m) in the separation of volatile compounds from Asturian apple cider juices, and was characterized using the Abraham solvation parameter model. The intra-day and inter-day precision of the chromatographic method was evaluated, obtaining relative standard deviations from 3.7 to 12.9% and from 7.4 to 18.0%, respectively. Furthermore, recoveries from 82.5 to 122% were achieved. Graphical Abstract Covalent bonding of an ionic liquid to inner column wall led to a great improvement of the separation efficiencies of stationary phases in gas chromatography.

  18. Volatile profile of wine Teran PTP

    Directory of Open Access Journals (Sweden)

    Helena BAŠA ČESNIK

    2015-11-01

    Full Text Available Teran PTP is a protected wine with a recognized traditional denomination produced from a grapevine variety ‘Refošk’ in winegrowing district Kras in Slovenia (European Union, 2009; Pravilnik, 2008. The aromatic profile of 82 Teran PTP wines produced in years 2011, 2012 and 2013 was monitored. Intotal the content of 16 volatile compounds was determined. The volatile compounds from wine were extracted following the liquid-liquid extraction and determined with a GC-MS method. The odour activity values and relative odour contributions were calculated for each volatile compound identified. Among sensorial important volatiles the highest odour activity values were determined for ethyl octanoate, ethyl hexanoate, isoamyl acetate and ethyl butyrate. Other research papers also showed, that all red wines investigated except one contained ethyl octanoate, ethyl hexanoate, isoamyl acetate and ethyl butyrate above sensory thresholds.

  19. Emerging Equity Market Volatility

    OpenAIRE

    Geert Bekaert; Harvey, Campbell R.

    1995-01-01

    Returns in emerging capital markets are very different from returns in developed markets. While most previous research has focused on average returns, we analyze the volatility of the returns in emerging equity markets. We characterize the time-series of volatility in emerging markets and explore the distributional foundations of the variance process. Of particular interest is evidence of asymmetries in volatility and the evolution of the variance process after periods of capital market refor...

  20. Volatility in Equilibrium

    DEFF Research Database (Denmark)

    Bollerslev, Tim; Sizova, Natalia; Tauchen, George

    Stock market volatility clusters in time, carries a risk premium, is fractionally inte- grated, and exhibits asymmetric leverage effects relative to returns. This paper develops a first internally consistent equilibrium based explanation for these longstanding empirical facts. The model is cast......, and the dynamic cross-correlations of the volatility measures with the returns calculated from actual high-frequency intra-day data on the S&P 500 aggregate market and VIX volatility indexes....

  1. 土壤中23种挥发性氯代烃和苯系物的测定%SIMULTANEOUS DETERMINATION OF 23 VOLATILE CHLORINATED HYDROCARBONS AND BENZENE SERIES IN SOIL SAMPLES

    Institute of Scientific and Technical Information of China (English)

    李丽君; 何炼; 边景辉; 孙宁

    2012-01-01

    建立了同时测定土壤中23种挥发性氯代烃和苯系物的吹扫捕集-气相色谱-质谱法.优化了试验条件,标准曲线在0.32×10-9~200.0×10-9范围内呈线性关系,方法检出限( 3S/N)为0.077×10-9~0.69×10-9,样品标准添加平均回收率86.5%~117.5%,相对标准偏差(n=7)在1.6 %~8.2%之间.%A method for simultaneous determination for 23 volatile chlorinated hydrocarbons and benzene series in soil samples by gas chromatography-mass spectrometry (GC-MS) with purge and trap pretreatment is introduced. The conditions of purge and trap, the qualification of GC-MS, and the centrifuge are confirmed. Under the best conditions, the liner range of the standard curve is 0.32 - 200.0 u,g/kg. The detection limits range of the method for the 23 volatile organic compounds are 0.077 - 0.69 μg/kg. The average recoveries are 86.5% to 117.5%, with precision of 1.6% - 8.2% (n =7). This fast and accurate method can be applied to determinate the 23 volatile organic compounds in batch soil samples with satisfactory results.

  2. Volatile loss from accreting icy protoplanets

    Science.gov (United States)

    Stevenson, D. J.

    1993-03-01

    A large self-gravitating body does not easily lose significant mass because the escape velocity is much larger than the sound speed of atmosphere-forming species under ambient thermal conditions. The most significant exceptions to this are giant impacts or impact jetting by fast-moving projectiles. A very small object (e.g. a comet) also does not easily lose significant volatile mass upon formation because the energy release associated with its accretion is so small. (It can however lose a great deal of mass if it is subsequently moved closer to the Sun.) I argue that there is an intermediate mass range (corresponding to bodies with radii of approximately 300-800 km) for which the ambient steady-state mass loss is a maximum. By ambient, I mean those conditions pertaining to the formation region of the body. By steady state, I mean to exclude infrequent traumas (giant impacts). The existence of a preferred intermediate mass arises through the competition of growing gravitational containment and growing energy release by accretion; it corresponds typically to GM/(Rcs2) approximately equals 2 to 4, where M is the protoplanet mass of radius R, and cs is the sound speed. Several factors determine the amount of volatile loss is this vulnerable zone during accretion but in general the loss is a substantial fraction of the volatiles, sometimes approaching 100 percent. The principal implication is that bodies larger than a few hundred kilometers in radius will not have a 'primitive' (i.e. cometary) composition. This is relevant for understanding Triton, Pluto, Charon, and perhaps Chiron.

  3. Differential attraction of malaria mosquitoes to volatile blends produced by human skin bacteria.

    Directory of Open Access Journals (Sweden)

    Niels O Verhulst

    Full Text Available The malaria mosquito Anopheles gambiae sensu stricto is mainly guided by human odour components to find its blood host. Skin bacteria play an important role in the production of human body odour and when grown in vitro, skin bacteria produce volatiles that are attractive to A. gambiae. The role of single skin bacterial species in the production of volatiles that mediate the host-seeking behaviour of mosquitoes has remained largely unknown and is the subject of the present study. Headspace samples were taken to identify volatiles that mediate this behaviour. These volatiles could be used as mosquito attractants or repellents. Five commonly occurring species of skin bacteria were tested in an olfactometer for the production of volatiles that attract A. gambiae. Odour blends produced by some bacterial species were more attractive than blends produced by other species. In contrast to odours from the other bacterial species tested, odours produced by Pseudomonas aeruginosa were not attractive to A. gambiae. Headspace analysis of bacterial volatiles in combination with behavioural assays led to the identification of six compounds that elicited a behavioural effect in A. gambiae. Our results provide, to our knowledge, the first evidence for a role of selected bacterial species, common on the human skin, in determining the attractiveness of humans to malaria mosquitoes. This information will be used in the further development of a blend of semiochemicals for the manipulation of mosquito behaviour.

  4. Differential Attraction of Malaria Mosquitoes to Volatile Blends Produced by Human Skin Bacteria

    Science.gov (United States)

    Verhulst, Niels O.; Andriessen, Rob; Groenhagen, Ulrike; Bukovinszkiné Kiss, Gabriella; Schulz, Stefan; Takken, Willem; van Loon, Joop J. A.; Schraa, Gosse; Smallegange, Renate C.

    2010-01-01

    The malaria mosquito Anopheles gambiae sensu stricto is mainly guided by human odour components to find its blood host. Skin bacteria play an important role in the production of human body odour and when grown in vitro, skin bacteria produce volatiles that are attractive to A. gambiae. The role of single skin bacterial species in the production of volatiles that mediate the host-seeking behaviour of mosquitoes has remained largely unknown and is the subject of the present study. Headspace samples were taken to identify volatiles that mediate this behaviour. These volatiles could be used as mosquito attractants or repellents. Five commonly occurring species of skin bacteria were tested in an olfactometer for the production of volatiles that attract A. gambiae. Odour blends produced by some bacterial species were more attractive than blends produced by other species. In contrast to odours from the other bacterial species tested, odours produced by Pseudomonas aeruginosa were not attractive to A. gambiae. Headspace analysis of bacterial volatiles in combination with behavioural assays led to the identification of six compounds that elicited a behavioural effect in A. gambiae. Our results provide, to our knowledge, the first evidence for a role of selected bacterial species, common on the human skin, in determining the attractiveness of humans to malaria mosquitoes. This information will be used in the further development of a blend of semiochemicals for the manipulation of mosquito behaviour. PMID:21209854

  5. Improvement of determinating seafloor benchmark position with large-scale horizontal heterogeneity in the ocean area

    Science.gov (United States)

    Uemura, Y.; Tadokoro, K.; Matsuhiro, K.; Ikuta, R.

    2015-12-01

    The most critical issue in reducing the accuracy of seafloor positioning system, GPS/Acoustic technique, is large-scale thermal gradient of sound-speed structure [Muto et al., 2008] due to the ocean current. For example, Kuroshio Current, near our observation station, forms this structure. To improve the accuracy of seafloor benchmark position (SBP), we need to directly measure the structure frequently, or estimate it from travel time residual. The former, we repeatedly measure the sound-speed at Kuroshio axis using Underway CTD and try to apply analysis method of seafloor positioning [Yasuda et al., 2015 AGU meeting]. The latter, however, we cannot estimate the structure using travel time residual until now. Accordingly, in this study, we focus on azimuthal dependence of Estimated Mean Sound-Speed (EMSS). EMSS is defined as distance between vessel position and estimated SBP divided by travel time. If thermal gradient exists and SBP is true, EMSS should have azimuthal dependence with the assumption of horizontal layered sound-speed structure in our previous analysis method. We use the data at KMC located on the central part of Nankai Trough, Japan on Jan. 28, 2015, because on that day KMC was on the north edge of Kuroshio, where we expect that thermal gradient exists. In our analysis method, the hyper parameter (μ value) weights travel time residual and rate of change of sound speed structure. However, EMSS derived from μ value determined by Ikuta et al. [2008] does not have azimuthal dependence, that is, we cannot estimate thermal gradient. Thus, we expect SBP has a large bias. Therefore, in this study, we use another μ value and examine whether EMSS has azimuthal dependence or not. With the μ value of this study, which is 1 order of magnitude smaller than the previous value, EMSS has azimuthal dependence that is consistent with observation day's thermal gradient. This result shows that we can estimate the thermal gradient adequately. This SBP displaces 25

  6. Factors affecting the volatilization of volatile organic compounds from wastewater

    Directory of Open Access Journals (Sweden)

    Junya Intamanee

    2006-09-01

    Full Text Available This study aimed to understand the influence of the wind speed (U10cm, water depth (h and suspended solids (SS on mass transfer coefficient (KOLa of volatile organic compounds (VOCs volatilized from wastewater. The novelty of this work is not the method used to determine KOLa but rather the use of actual wastewater instead of pure water as previously reported. The influence of U10cm, h, and SS on KOLa was performed using a volatilization tank with the volume of 100-350 L. Methyl Ethyl Ketone (MEK was selected as a representative of VOCs investigated here in. The results revealed that the relationship between KOLa and the wind speeds falls into two regimes with a break at the wind speed of 2.4 m/s. At U10cm 2.4 m/s, KOLa increased more rapidly. The relationship between KOLa and U10cm was also linear but has a distinctly higher slope. For the KOLa dependency on water depth, the KOLa decreased significantly with increasing water depth up to a certain water depth after that the increase in water depth had small effect on KOLa. The suspended solids in wastewater also played an important role on KOLa. Increased SS resulted in a significant reduction of KOLa over the investigated range of SS. Finally, the comparison between KOLa obtained from wastewater and that of pure water revealed that KOLa from wastewater were much lower than that of pure water which was pronounced at high wind speed and at small water depth. This was due the presence of organic mass in wastewater which provided a barrier to mass transfer and reduced the degree of turbulence in the water body resulting in low volatilization rate and thus KOLa. From these results, the mass transfer model for predicting VOCs emission from wastewater should be developed based on the volatilization of VOCs from wastewater rather than that from pure water.

  7. Residual dipolar coupling constants and structure determination of large DNA duplexes

    Energy Technology Data Exchange (ETDEWEB)

    Mauffret, Olivier; Tevanian, Georges; Fermandjian, Serge [Institut Gustave-Roussy, Departement de Biologie et Pharmacologie Structurales (France)], E-mail: sfermand@igr.fr

    2002-12-15

    Several NMR works have shown that long-range information provided by residual dipolar couplings (RDCs) significantly improve the global structure definition of RNAs and DNAs. Most of these are based on the use of a large set of RDCs, the collect of which requires samples labeled with {sup 13}C, {sup 15}N, and sometimes, {sup 2}H. Here, we carried out torsion-angle dynamics simulations on a non-self complementary DNA fragment of 17 base-pairs, d(GGAAAATATCTAGCAGT).(ACTGCTAGAGATTTTCC). This reproduces the U5 LTR distal end of the HIV-1 cDNA that contains the enzyme integrase binding site. Simulations aimed at evaluating the impact of RDCs on the structure definition of long oligonucleotides, were performed in incorporating (i) nOe-distances at both < 4.5 A and < 5 A; (ii) a small set of {sup 13}C-{sup 1}H RDCs, easily detectable at the natural abundance, and (iii) a larger set of RDCs only accessible through the {sup 13}C labeling of DNAs. Agreement between a target structure and a simulated structure was measured in terms of precision and accuracy. Results allowed to define conditions in which accurate DNA structures can be determined. We confirmed the strong impact of RDCs on the structure determination, and, above all, we found that a small set of RDC constraints (ca. 50) detectable at the natural abundance is sufficient to accurately derive the global and local DNA duplex structures when used in conjunction with nOe-distances < 5 A.

  8. Reduced Heart Rate Volatility

    Science.gov (United States)

    Grogan, Eric L.; Morris, John A.; Norris, Patrick R.; France, Daniel J.; Ozdas, Asli; Stiles, Renée A.; Harris, Paul A.; Dawant, Benoit M.; Speroff, Theodore

    2004-01-01

    Objective: To determine if using dense data capture to measure heart rate volatility (standard deviation) measured in 5-minute intervals predicts death. Background: Fundamental approaches to assessing vital signs in the critically ill have changed little since the early 1900s. Our prior work in this area has demonstrated the utility of densely sampled data and, in particular, heart rate volatility over the entire patient stay, for predicting death and prolonged ventilation. Methods: Approximately 120 million heart rate data points were prospectively collected and archived from 1316 trauma ICU patients over 30 months. Data were sampled every 1 to 4 seconds, stored in a relational database, linked to outcome data, and de-identified. HR standard deviation was continuously computed over 5-minute intervals (CVRD, cardiac volatility–related dysfunction). Logistic regression models incorporating age and injury severity score were developed on a test set of patients (N = 923), and prospectively analyzed in a distinct validation set (N = 393) for the first 24 hours of ICU data. Results: Distribution of CVRD varied by survival in the test set. Prospective evaluation of the model in the validation set gave an area in the receiver operating curve of 0.81 with a sensitivity and specificity of 70.1 and 80.0, respectively. CVRD predict death as early as 24 hours in the validation set. Conclusions: CVRD identifies a subgroup of patients with a high probability of dying. Death is predicted within first 24 hours of stay. We hypothesize CVRD is a surrogate for autonomic nervous system dysfunction. PMID:15319726

  9. Experimental determination of the partitioning coefficient and volatility of important BVOC oxidation products using the Aerosol Collection Module (ACM) coupled to a PTR-ToF-MS

    Science.gov (United States)

    Gkatzelis, G.; Hohaus, T.; Tillmann, R.; Schmitt, S. H.; Yu, Z.; Schlag, P.; Wegener, R.; Kaminski, M.; Kiendler-Scharr, A.

    2015-12-01

    Atmospheric aerosol can alter the Earth's radiative budget and global climate but can also affect human health. A dominant contributor to the submicrometer particulate matter (PM) is organic aerosol (OA). OA can be either directly emitted through e.g. combustion processes (primary OA) or formed through the oxidation of organic gases (secondary organic aerosol, SOA). A detailed understanding of SOA formation is of importance as it constitutes a major contribution to the total OA. The partitioning between the gas and particle phase as well as the volatility of individual components of SOA is yet poorly understood adding uncertainties and thus complicating climate modelling. In this work, a new experimental methodology was used for compound-specific analysis of organic aerosol. The Aerosol Collection Module (ACM) is a newly developed instrument that deploys an aerodynamic lens to separate the gas and particle phase of an aerosol. The particle phase is directed to a cooled sampling surface. After collection particles are thermally desorbed and transferred to a detector for further analysis. In the present work, the ACM was coupled to a Proton Transfer Reaction-Time of Flight-Mass Spectrometer (PTR-ToF-MS) to detect and quantify organic compounds partitioning between the gas and particle phase. This experimental approach was used in a set of experiments at the atmosphere simulation chamber SAPHIR to investigate SOA formation. Ozone oxidation with subsequent photochemical aging of β-pinene, limonene and real plant emissions from Pinus sylvestris (Scots pine) were studied. Simultaneous measurement of the gas and particle phase using the ACM-PTR-ToF-MS allows to report partitioning coefficients of important BVOC oxidation products. Additionally, volatility trends and changes of the SOA with photochemical aging are investigated and compared for all systems studied.

  10. Experimental setup and analytical methods for the non-invasive determination of volatile organic compounds, formaldehyde and NO{sub x} in exhaled human breath

    Energy Technology Data Exchange (ETDEWEB)

    Riess, Ulrich; Tegtbur, Uwe [Hannover Medical School, Sports Physiology and Sports Medicine, Carl-Neuberg-Str. 1, 30625 Hannover (Germany); Fauck, Christian; Fuhrmann, Frank; Markewitz, Doreen [Fraunhofer WKI, Department of Material Analysis and Indoor Chemistry, Bienroder Weg 54 E, 38108 Braunschweig (Germany); Salthammer, Tunga, E-mail: tunga.salthammer@wki.fraunhofer.de [Fraunhofer WKI, Department of Material Analysis and Indoor Chemistry, Bienroder Weg 54 E, 38108 Braunschweig (Germany)

    2010-06-11

    Different analytical devices were tested and evaluated for their suitability of breath gas analysis by examining the physiological parameters and chemical substances in the exhaled breath of ten healthy probands during light cycling in dependence of methanol-rich nutrition. The probands exercised under normal breathing conditions on a bicycle ergometer. Breath air was exhaled into a glass cylinder and collected under steady-state conditions. Non-invasively measured parameters were pulse rate, breath frequency, temperature, relative humidity, NO{sub x}, total volatile organic compounds (TVOC{sub PAS}), carbon dioxide (CO{sub 2}), formaldehyde, methanol, acetaldehyde, acetone, isoprene and volatile organic compounds (VOCs). Methanol rich food and beverages strongly influenced the concentration of methanol and other organic substances in human breath. On the other hand, nutrition and smoking had no clear effect on the physical conditions of the probands. The proton transfer reaction mass spectrometry (PTR-MS) method was found to be very suitable for the analysis of breath gas but the m/z 31, if assigned to formaldehyde, is sensitive to interferences. The time vs. concentration curves of nitric oxide showed sudden peaks up to 120 ppb in most of the measurements. In one case a strong interference of the NO{sub x} signal was observed. The time resolved analysis of exhaled breath gas is of high capability and significance for different applications if reliable analytical techniques are used. Some compounds like nitric oxide (NO), methanol, different VOCs as well as sum parameters like TVOC{sub PAS} are especially suitable as markers. Formaldehyde, which is rapidly metabolized in the human body, could be measured reliably as a trace component by the acetylacetone (acac) method but not by PTR-MS.

  11. Determination of summer monsoon onset and its related large-scale circulation characteristics over Pakistan

    Science.gov (United States)

    Latif, M.; Syed, F. S.

    2016-08-01

    The onset of summer monsoon over the Core Monsoon Region of Pakistan (CMRP) has been investigated in this study using observational daily rainfall and Precipitable Water (PW) data sets. An objective criterion is proposed to define monsoon onset dates by employing Precipitation Index and Normalized Precipitable Water Index techniques. The climatological mean summer monsoon onset dates over CMRP based on daily rainfall data sets are observed to be 1 July and 30 June in the station and gridded data sets, respectively. Whereas the daily PW-based climatological mean onset date is 30 June. The year-wise onset dates determined through station and gridded rainfall data sets are very similar but these dates differ in case of PW-based onsets. The evolution of large-scale circulation anomalies and thermodynamic structure leading monsoon onset over Pakistan shows that a strong positive temperature and geopotential height anomalies appear over the northwestern part of the core region in the upper atmosphere. This warm geopotential height anomaly gets strengthen as the monsoon onset approaches. The temperature anomalies are barotropic whereas the geopotential height anomalies are baroclinic with the presence of low level anticyclone over the Tibetan Plateau. A moisture convergence zone along the foothill of Himalayas and low level moisture convergence zone over the north Arabian Sea set the stage for the moisture carrying monsoon winds to blow inland towards CMRP. The moisture is mainly supplied from the Arabian Sea, as the low pressure system approaches CMRP from the Bay of Bengal.

  12. Understanding Financial Market Volatility

    NARCIS (Netherlands)

    A. Opschoor (Anne)

    2014-01-01

    markdownabstract__Abstract__ Volatility has been one of the most active and successful areas of research in time series econometrics and economic forecasting in recent decades. Loosely speaking, volatility is defined as the average magnitude of fluctuations observed in some phenomenon over time. Wi

  13. Improving Garch Volatility Forecasts

    NARCIS (Netherlands)

    Klaassen, F.J.G.M.

    1998-01-01

    Many researchers use GARCH models to generate volatility forecasts. We show, however, that such forecasts are too variable. To correct for this, we extend the GARCH model by distinguishing two regimes with different volatility levels. GARCH effects are allowed within each regime, so that our model

  14. Understanding Financial Market Volatility

    NARCIS (Netherlands)

    A. Opschoor (Anne)

    2014-01-01

    markdownabstract__Abstract__ Volatility has been one of the most active and successful areas of research in time series econometrics and economic forecasting in recent decades. Loosely speaking, volatility is defined as the average magnitude of fluctuations observed in some phenomenon over

  15. Volatile metabolites from actinomycetes

    DEFF Research Database (Denmark)

    Scholler, C.E.G.; Gurtler, H.; Pedersen, R.

    2002-01-01

    Twenty-six Streptomyces spp. were screened for their volatile production capacity on yeast starch agar. The volatile organic compounds (VOCs) were concentrated on a porous polymer throughout an 8-day growth period. VOCs were analyzed by gas chromatography with flame ionization detection and ident...

  16. The fate of volatiles in mid-ocean ridge magmatism

    CERN Document Server

    Keller, Tobias; Hirschmann, Marc M

    2016-01-01

    Deep-Earth volatile cycles couple the mantle with near-surface reservoirs. Volatiles are emitted by volcanism and, in particular, from mid-ocean ridges, which are the most prolific source of basaltic volcanism. Estimates of volatile extraction from the asthenosphere beneath ridges typically rely on measurements of undegassed lavas combined with simple petrogenetic models of the mean degree of melting. Estimated volatile fluxes have large uncertainties; this is partly due to a poor understanding of how volatiles are transported by magma in the asthenosphere. Here, we assess the fate of mantle volatiles through numerical simulations of melting and melt transport at mid-ocean ridges. Our simulations are based on two-phase, magma/mantle dynamics theory coupled to an idealised thermodynamic model of mantle melting in the presence of water and carbon dioxide. We combine simulation results with catalogued observations of all ridge segments to estimate a range of likely volatile output from the global mid-ocean ridge...

  17. Possible Sources of Polar Volatiles

    Science.gov (United States)

    Schultz, P. H.

    2011-12-01

    : surface layer of atomic/molecules over a regolith containing an assortment of cold-trapped elements (Na/Ca/Mg/K/Ag/Hg) and compounds (OH, CO, H2). In addition to the solar flux, cometary dust dominates the impact flux for particles less than 1g and dominates impact flashes observed telescopically (Cooke, pers. comm.). While large, volatile-rich impactors may be less frequent, they have the potential for injecting significant quantities (10-15%) into impact melts (Harris and Schultz, 2011). In addition, laboratory impact experiments at the NASA Ames Vertical Gun Range used high-speed spectroscopy to illustrate the capture of volatile fractions below the surface during hypervelocity impacts. On the Moon, melt-trapped volatiles comprising the regolith would be gradually recycled during each lunation during impact gardening, thereby titrating the supply of volatiles to the polar deep freeze. Consequently, diverse sources likely contributed this potpourri of trapped cold-trapped volatile

  18. Determination of volatile organic acids and inorganic anions in pharmaceutical wastewater by ion chromatography%离子色谱法测定制药废水中挥发性有机酸及无机阴离子

    Institute of Scientific and Technical Information of China (English)

    王强; 王路光; 王靖飞; 李洪波

    2009-01-01

    An ion chromatographic method for simultaneous determination of volatile organic acids and inorganic anions in pharmacentical wastewater was developed, using NaOH as eluent, ion exchange column for separation, and thermal conductivity detector for detection. Eight volatile organic acids and inorganic anions in pharmaceutical wastewater were separated in 28.0 min. The recoveries were 85.9%~109.5% and RSDs were 2.9%~10.9%. The method can be used for analysis of volatile organic acids and inorganic anions in wastewater in the production of penicillin and vitamin C.%建立了以NaOH为淋洗液、离子交换色谱柱为分析柱、用电导检测器进行检测的制药废水中有机酸和无机阴离子的离子色谱分析方法.结果表明,在28.0 min内可以分离出废水中8种主要挥发性有机酸与无机阴离子.方法回收率为85.9%~109.5 %,相对标准偏差为2.9%~10.9%.该法可用于青霉素生产废水、VC生产废水等制药废水中有机酸和无机阴离子的快速、准确分析,结果令人满意.

  19. 气相色谱法测定姜味草挥发油中橙花醛与香叶醛%GC Determination of Neral and Geranial in Volatile Oil of Micromeria Biflora.

    Institute of Scientific and Technical Information of China (English)

    李坤平; 江嘉冕; 陈潮珠; 劳碧婷

    2011-01-01

    采用水蒸气蒸馏法提取姜味草挥发油,用气相色谱法-氢火焰离子化检测器测定挥发油中橙花醛和香叶醛的含量。橙花醛和香叶醛的线性范围分别为0.0971~0.5826g·L~(-1)和0.1152~0.6912g·L~(-1)方法用于测定4批次姜味草挥发油中橙花醛与香叶醛的含量,橙花醛与香叶醛的质量分数分别为25.00%,29.57%,26.30%,28.59%和36.41%,43.80%,38.72%,41.52%。%The volatile oil of Micromeria biflora,was extracted by steam distillation,and the contents of neral and geranial in volatile oil were determined by GC with flame ionization detector(FID).Linearity ranges of neral and geranial found were between 0.097 1-0.582 6 g·L~(-1) and 0.115 2-0.691 2 g·L~(-1) respectively.The proposed method was applied to the analysis of samples from 4 batches of volatile oil of Micromeria biflora.,giving the results as follow:25.00%.29.57%,26.30%,28.59%for neral and 36.41%,43.80%,38.72%,41.52% for geranial.

  20. Determinants of Functional and Structural Properties of Large Arteries in Healthy Individuals

    Energy Technology Data Exchange (ETDEWEB)

    Tolezani, Elaine Cristina; Costa-Hong, Valéria, E-mail: hong.valeria@gmail.com; Correia, Gustavo; Mansur, Alfredo José; Drager, Luciano Ferreira; Bortolotto, Luiz Aparecido [Instituto do Coração, Hospital das Clínicas, Faculdade de Medicina, Universidade de São Paulo, São Paulo, SP (Brazil)

    2014-11-15

    Changes in the properties of large arteries correlate with higher cardiovascular risk. Recent guidelines have included the assessment of those properties to detect subclinical disease. Establishing reference values for the assessment methods as well as determinants of the arterial parameters and their correlations in healthy individuals is important to stratify patients. To assess, in healthy adults, the distribution of the values of pulse wave velocity, diameter, intima-media thickness and relative distensibility of the carotid artery, in addition to assessing the demographic and clinical determinants of those parameters and their correlations. This study evaluated 210 individuals (54% women; mean age, 44 ± 13 years) with no evidence of cardiovascular disease. The carotid-femoral pulse wave velocity was measured with a Complior{sup ®} device. The functional and structural properties of the carotid artery were assessed by using radiofrequency ultrasound. The means of the following parameters were: pulse wave velocity, 8.7 ± 1.5 m/s; diameter, 6,707.9 ± 861.6 μm; intima-media thickness, 601 ± 131 μm; relative distensibility, 5.3 ± 2.1%. No significant difference related to sex or ethnicity was observed. On multiple linear logistic regression, the factors independently related to the vascular parameters were: pulse wave velocity, to age (p < 0.01) and triglycerides (p = 0.02); intima-media thickness, to age (p < 0.01); diameter, to creatinine (p = 0.03) and age (p = 0.02); relative distensibility, to age (p < 0.01) and systolic and diastolic blood pressures (p = 0.02 and p = 0.01, respectively). Pulse wave velocity showed a positive correlation with intima media thickness (p < 0.01) and with relative distensibility (p < 0.01), while diameter showed a positive correlation with distensibility (p = 0.03). In healthy individuals, age was the major factor related to aortic stiffness, while age and diastolic blood pressure related to the carotid functional measure

  1. Determinants of Functional and Structural Properties of Large Arteries in Healthy Individuals

    Directory of Open Access Journals (Sweden)

    Elaine Cristina Tolezani

    2014-11-01

    Full Text Available Background: Changes in the properties of large arteries correlate with higher cardiovascular risk. Recent guidelines have included the assessment of those properties to detect subclinical disease. Establishing reference values for the assessment methods as well as determinants of the arterial parameters and their correlations in healthy individuals is important to stratify patients. Objective: To assess, in healthy adults, the distribution of the values of pulse wave velocity, diameter, intima-media thickness and relative distensibility of the carotid artery, in addition to assessing the demographic and clinical determinants of those parameters and their correlations. Methods: This study evaluated 210 individuals (54% women; mean age, 44 ± 13 years with no evidence of cardiovascular disease. The carotid-femoral pulse wave velocity was measured with a Complior® device. The functional and structural properties of the carotid artery were assessed by using radiofrequency ultrasound. Results: The means of the following parameters were: pulse wave velocity, 8.7 ± 1.5 m/s; diameter, 6,707.9 ± 861.6 μm; intima-media thickness, 601 ± 131 μm; relative distensibility, 5.3 ± 2.1%. No significant difference related to sex or ethnicity was observed. On multiple linear logistic regression, the factors independently related to the vascular parameters were: pulse wave velocity, to age (p < 0.01 and triglycerides (p = 0.02; intima-media thickness, to age (p < 0.01; diameter, to creatinine (p = 0.03 and age (p = 0.02; relative distensibility, to age (p < 0.01 and systolic and diastolic blood pressures (p = 0.02 and p = 0.01, respectively. Pulse wave velocity showed a positive correlation with intima media thickness (p < 0.01 and with relative distensibility (p < 0.01, while diameter showed a positive correlation with distensibility (p = 0.03. Conclusion: In healthy individuals, age was the major factor related to aortic stiffness, while age and diastolic

  2. Refractory Hypertension: Determination of Prevalence, Risk Factors and Comorbidities in a Large, Population-Based Cohort

    Science.gov (United States)

    Calhoun, David A.; Booth, John N.; Oparil, Suzanne; Irvin, Marguerite R.; Shimbo, Daichi; Lackland, Daniel T.; Howard, George; Safford, Monika M.; Muntner, Paul

    2014-01-01

    Refractory hypertension is an extreme phenotype of antihypertensive treatment failure. Participants in the REasons for Geographic And Racial Differences in Stroke (REGARDS) Study, a large (n=30,239), population-based cohort were evaluated to determine the prevalence of refractory hypertension and associated cardiovascular risk factors and comorbidities. Refractory hypertension was defined as uncontrolled blood pressure (systolic/diastolic ≥ 140/90 mm Hg) on ≥ 5 antihypertensive drug classes. Participants with resistant hypertension (systolic/diastolic ≥140/90 mm Hg on ≥ 3 orhypertensive participants served as comparator groups. Of 14,809 REGARDS participants receiving antihypertensive treatment, 78 (0.5%) had refractory hypertension. The prevalence of refractory hypertension was 3.6% among participants with resistant hypertension(n=2,144) and 41.7% among participants on 5 or more antihypertensive drug classes. Among all hypertensive participants, African American race, male gender, living in the stroke belt or buckle, higher body mass index, lower heart rate, reduced estimated glomerular filtration rate, albuminuria, diabetes and history of stroke and coronary heart disease were associated with refractory hypertension. Compared to resistant hypertension, prevalence ratios for refractory hypertension were increased for African Americans (3.00, 95% CI 1.68 – 5.37) and those with albuminuria (2.22, 95% CI 1.40 – 3.52) and diabetes (2.09, 95% CI 1.32 – 3.31). The median 10-year Framingham risk for coronary heart disease and stroke was higher among participants with refractory hypertension compared to either comparator group. These data indicate that while resistant hypertension is relatively common among treated hypertensive patients, true antihypertensive treatment failure is rare. PMID:24324035

  3. Determination of paleoseismic activity over a large time-scale: Fault scarp dating with 36Cl

    Science.gov (United States)

    Mozafari Amiri, Nasim; Tikhomirov, Dmitry; Sümer, Ökmen; Özkaymak, Çaǧlar; Uzel, Bora; Ivy-Ochs, Susan; Vockenhuber, Christof; Sözbilir, Hasan; Akçar, Naki

    2016-04-01

    Bedrock fault scarps are the most direct evidence of past earthquakes to reconstruct seismic activity in a large time-scale using cosmogenic 36Cl dating if built in carbonates. For this method, a surface along the fault scarp with a minimum amount of erosion is required to be chosen as an ideal target point. The section of the fault selected for sampling should cover at least two meters of the fault surface from the lower part of the scarp, where intersects with colluvium wedge. Ideally, sampling should be performed on a continuous strip along the direction of the fault slip direction. First, samples of 10 cm high and 15 cm wide are marked on the fault surface. Then, they are collected using cutters, hammer and chisel in a thickness of 3 cm. The main geometrical factors of scarp dip, scarp height, top surface dip and colluvium dip are also measured. Topographic shielding in the sampling spot is important to be estimated as well. Moreover, density of the fault scarp and colluvium are calculated. The physical and chemical preparations are carried in laboratory for AMS and chemical analysis of the samples. A Matlab® code is used for modelling of seismically active periods based on increasing production rate of 36Cl following each rupture, when a buried section of a fault is exposed. Therefore, by measuring the amount of cosmogenic 36Cl versus height, the timing of major ruptures and their offsets are determined. In our study, Manastır, Mugırtepe and Rahmiye faults in Gediz graben, Priene-Sazlı, Kalafat and Yavansu faults in Büyük Menderes graben and Ören fault in Gökava half-graben have been examined in the seismically active region of Western Turkey. Our results reconstruct at least five periods of high seismic activity during the Holocene time, three of which reveal seismic ruptures beyond the historical pre-existing data.

  4. Refractory hypertension: determination of prevalence, risk factors, and comorbidities in a large, population-based cohort.

    Science.gov (United States)

    Calhoun, David A; Booth, John N; Oparil, Suzanne; Irvin, Marguerite R; Shimbo, Daichi; Lackland, Daniel T; Howard, George; Safford, Monika M; Muntner, Paul

    2014-03-01

    Refractory hypertension is an extreme phenotype of antihypertensive treatment failure. Participants in the REasons for Geographic And Racial Differences in Stroke (REGARDS) Study, a large (n=30 239), population-based cohort were evaluated to determine the prevalence of refractory hypertension and associated cardiovascular risk factors and comorbidities. Refractory hypertension was defined as uncontrolled blood pressure (systolic/diastolic, ≥140/90 mm Hg) on ≥5 antihypertensive drug classes. Participants with resistant hypertension (systolic/diastolic, ≥140/90 mm Hg on ≥3 or hypertension served as comparator groups. Of 14 809 REGARDS participants receiving antihypertensive treatment, 78 (0.5%) had refractory hypertension. The prevalence of refractory hypertension was 3.6% among participants with resistant hypertension (n=2144) and 41.7% among participants on ≥5 antihypertensive drug classes. Among all participants with hypertension, black race, male sex, living in the stroke belt or buckle, higher body mass index, lower heart rate, reduced estimated glomerular filtration rate, albuminuria, diabetes mellitus, and history of stroke and coronary heart disease were associated with refractory hypertension. Compared with resistant hypertension, prevalence ratios for refractory hypertension were increased for blacks (3.00; 95% confidence interval, 1.68-5.37) and those with albuminuria (2.22; 95% confidence interval, 1.40-3.52) and diabetes mellitus (2.09; 95% confidence interval, 1.32-3.31). The median 10-year Framingham risk for coronary heart disease and stroke was higher among participants with refractory hypertension when compared with those with either comparator group. These data indicate that although resistant hypertension is relatively common among treated patients with hypertension, true antihypertensive treatment failure is rare.

  5. Determination of nicotine, tar, volatile organic compounds and carbonyls in mainstream cigarette smoke using a glass filter and a sorbent cartridge followed by the two-phase/one-pot elution method with carbon disulfide and methanol.

    Science.gov (United States)

    Uchiyama, Shigehisa; Hayashida, Hideki; Izu, Rina; Inaba, Yohei; Nakagome, Hideki; Kunugita, Naoki

    2015-12-24

    We have developed a new analytical method for the determination of nicotine, tar, volatile organic compounds and carbonyls in main-stream cigarette smoke using a sorbent cartridge packed with Carboxen 572 (CX-572) and a Cambridge filter pad (CFP) followed by the two-phase/one-pot elution method. A CX-572 cartridge is installed between the intake of the CFP and the pump of the smoking machine. Gaseous compounds collected with the CX-572 cartridge and total particulate matter (TPM) collected with the CFP are coeluted simultaneously in the same vial and then analyzed by high-performance liquid chromatography (HPLC), gas chromatography-mass spectrometry (GC/MS) and gas chromatograph-thermal conductivity detector (GC/TCD). Carbonyl compounds are determined by adding derivatizing reagent (2,4-dinitrophenylhydrazine, DNPH) to the eluate followed by HPLC analysis. VOCs and nicotine are determined by GC/MS, and water is determined by GC/TCD. The same sample eluate solution is used for HPLC, GC/MS and GC/TCD analyses. As a result of measuring main-stream cigarette smoke generated from reference cigarettes, almost all carbonyl compounds and VOCs except formaldehyde were passed through a CFP and trapped in a CX-572 cartridge. 100% of nicotine, tar and TPM were trapped in a CFP. 50% of water and 53% of formaldehyde were trapped in a CFP. The one-pot data is almost equal to the sums of CFP (particulate matter) and CX-572 (gaseous compounds) data. The two-phase/one-pot elution method can simultaneously measure nicotine, tar, volatile organic compounds and carbonyl compounds in cigarette smoke with simple operation and small amounts of reagents. Copyright © 2015 Elsevier B.V. All rights reserved.

  6. Flower volatiles, crop varieties and bee responses.

    Directory of Open Access Journals (Sweden)

    Björn K Klatt

    Full Text Available Pollination contributes to an estimated one third of global food production, through both the improvement of the yield and the quality of crops. Volatile compounds emitted by crop flowers mediate plant-pollinator interactions, but differences between crop varieties are still little explored. We investigated whether the visitation of crop flowers is determined by variety-specific flower volatiles using strawberry varieties (Fragaria x ananassa Duchesne and how this affects the pollination services of the wild bee Osmia bicornis L. Flower volatile compounds of three strawberry varieties were measured via headspace collection. Gas chromatography showed that the three strawberry varieties produced the same volatile compounds but with quantitative differences of the total amount of volatiles and between distinct compounds. Electroantennographic recordings showed that inexperienced females of Osmia bicornis had higher antennal responses to all volatile compounds than to controls of air and paraffin oil, however responses differed between compounds. The variety Sonata was found to emit a total higher level of volatiles and also higher levels of most of the compounds that evoked antennal responses compared with the other varieties Honeoye and Darselect. Sonata also received more flower visits from Osmia bicornis females under field conditions, compared with Honeoye. Our results suggest that differences in the emission of flower volatile compounds among strawberry varieties mediate their attractiveness to females of Osmia bicornis. Since quality and quantity of marketable fruits depend on optimal pollination, a better understanding of the role of flower volatiles in crop production is required and should be considered more closely in crop-variety breeding.

  7. 76 FR 76146 - Large Power Transformers From the Republic of Korea: Postponement of Preliminary Determination of...

    Science.gov (United States)

    2011-12-06

    ... transformers from the Republic of Korea (Korea). See Large Power Transformers from the Republic of Korea: Initiation of Antidumping Duty Investigation, 76 FR 49439 (August 10, 2011). The current deadline for the... International Trade Administration Large Power Transformers From the Republic of Korea: Postponement...

  8. Volatile compounds in meat and meat products

    Directory of Open Access Journals (Sweden)

    Monika KOSOWSKA

    Full Text Available Abstract Meaty flavor is composed of a few hundreds of volatile compounds, only minor part of which are responsible for the characteristic odor. It is developed as a result of multi-directional reactions proceeding between non-volatile precursors contained in raw meat under the influence of temperature. The volatile compounds are generated upon: Maillard reactions, lipid oxidation, interactions between Maillard reaction products and lipid oxidation products as well as upon thiamine degradation. The developed flavor is determined by many factors associated with: raw material (breed, sex, diet and age of animal, conditions and process of slaughter, duration and conditions of meat storage, type of muscle, additives applied and the course of the technological process. The objective of this review article is to draw attention to the issue of volatile compounds characteristic for meat products and factors that affect their synthesis.

  9. Examining Moderate Volatile Loss through Lunar History

    Science.gov (United States)

    Saxena, Prabal; Killen, Rosemary M.; Airapetian, Vladimir; Petro, Noah; Mandell, Avi

    2017-06-01

    While the Moon and bulk silicate earth (BSE) share many compositional similarities, a notable difference is the apparent depletion of moderate volatiles in lunar samples. Depletion of elements such as sodium and potassium relative to BSE composition has been observed in Apollo samples. The source of these depletions is poorly understood but may be a result of preferential accretion of volatile-rich melt in the inner disk to the Earth during Moon formation.However, recent Kepler data has indicated that stellar analogues to our Sun experience enhanced flare activity early in their evolution. This implies that the Sun may have had a higher frequency and energy of flares and associated Coronal Mass Ejections (CME) in its distant past. We examine the potential impacts of this increased activity on lunar exosphere generation and specifically on potential loss of moderate volatiles including sodium and potassium.We use a surface bounded exosphere model that incorporates multiple processes including photon stimulated desorption, kinetic sputtering and impact vaporization in order to study potential moderate volatile loss under a variety of different conditions. This model is informed by appropriate solar wind and CME properties, which includes CMEs of different energies. We also incorporate regolith overturn to determine ranges of potential bulk depletion of moderate volatiles from the lunar regolith.Our work is aimed at determining the potential impact of solar activity on the depletion of moderate volatiles in the lunar regolith. Such a contribution is important to ascertain in order to isolate the depletion of volatiles due to disk processes and may thus help constrain details of the Moon's formation. Finally, we also examine the potential of lunar abundances of moderate volatiles as an observational tracer of past solar activity.

  10. Mantle Volatiles - Distribution and Consequences

    Science.gov (United States)

    Luth, R. W.

    2003-12-01

    O and 10-44% of the CO2 that is subducted is returned to the surface in arc magmatism. He emphasized that the "missing" volatiles may have multiple fates, including incorporation into the mantle wedge, large-scale fluid flow up along the interface between the subducting slab and overlying mantle, and transport into the deeper mantle.Because of the hydrous nature of arc magmatism, a common hypothesis is that there is a hydrous phase that breaks down at subarc conditions to trigger melting in the overlying mantle wedge to produce arc magmas. A key research goal has been to identify this phase, or phases. For example, serpentine in peridotite will break down during subduction to produce olivine+orthopyroxene+fluid or, in cooler slabs, a progression of DHMSs, the last of which may survive into the transition zone.At some point, however, because of the limited thermal or pressure stability of the hydrous phases, water will be liberated from the slab into the surrounding mantle. At this point, the water will either exist as a fluid, a melt - or something intermediate if we are above the second critical end point in the relevant system (Wyllie and Ryabchikov, 2000) - or it may dissolve into nominally anhydrous phases.The understanding of the relevant phase relations for the other volatiles is not as advanced. For carbon, we have a reasonable understanding of its phase stability in the mantle, but there is still no good understanding of the relative importance of carbonates, elemental carbon, and other forms as hosts for carbon in the mantle. In the upper mantle, sulfur resides primarily in sulfides; their behavior during partial melting will play a major role in the geochemical cycling of sulfur as well as of chalcophile elements. The halogens are rare (and rarely studied) in mantle-derived samples; more insight into their behavior is currently coming from the study of mantle-derived magmas.This review will first consider the evidence from mantle-derived magmas pertaining

  11. Determination of volatile organic compounds including alcohols in refill fluids and cartridges of electronic cigarettes by headspace solid-phase micro extraction and gas chromatography-mass spectrometry.

    Science.gov (United States)

    Lim, Hyun-Hee; Shin, Ho-Sang

    2017-02-01

    An analytical method for the detection of 14 volatile organic compounds (VOCs) was developed to investigate VOCs in refill fluids and cartridges of electronic cigarettes (EC) using headspace solid-phase micro extraction (HS-SPME) coupled with gas chromatography-mass spectrometry (GC-MS). In total, 14 VOCs were identified and quantified in 283 flavored liquids, 21 nicotine liquids, and 12 disposable cartridges. The detected concentration ranges of the VOCs are as follows: benzene (0.008-2.28 mg L(-1)), toluene (0.006-0.687 mg L(-1)), ethylbenzene (0.01-1.21 mg L(-1)), m-xylene (0.002-1.13 mg L(-1)), p-xylene (0.007-2.8 mg L(-1)), o-xylene (0.004-2.27 mg L(-1)), styrene (0.011-0.339 mg L(-1)), ethyl acetate (0.3-669.9 mg L(-1)), ethanol (16-38,742 mg L(-1)), methanol (66-3375 mg L(-1)), pyridine (0.077-99.7 mg L(-1)), acetylpyrazine (0.077-147 mg L(-1)), 2,3,5-trimethylpyrazine (0.008-96.8 mg L(-1)), and octamethylcyclotetrasiloxane (0.1-57.2 mg L(-1)). Benzene, toluene, ethylbenzene, m-xylene, p-xylene, and o-xylene coexisted in samples, which may have originated from the use of petrogenic hydrocarbons as an extraction solvent for flavor and nicotine from natural plants. The maximum detected concentrations of benzene, methanol, and ethanol in liquid samples were found in quantities higher than their authorized maximum limits as residual solvents in pharmaceutical products.

  12. On guidance and volatility

    NARCIS (Netherlands)

    Billings, M.B.; Jennings, R.; Lev, B.

    2013-01-01

    Survey evidence suggests that managers voluntarily disclose information, particularly earnings guidance, with an aim toward dampening share price volatility. Yet, consultants and influential institutions advise against providing guidance — citing fears of litigation and market penalties associated w

  13. Dynamic Volatility Arbitrage

    DEFF Research Database (Denmark)

    Dorn, Jochen

    profit on well-developed markets. Dynamic participation features on cross asset portfolios are at rst sight a remedy to that dilemma. Based on volatility thresholds and portfolio re-balancing, the fund engineers try to create a "volatility guaranteed" investment opportunity by surfing on the unusual high...... concepts, next to nothing is known about position reverting strategies and how, and -even more important- in which context they are applied in practice. In the recent market downturn only one sector generated signicant profits for the leading investment banks: Volatility trading activities, namely on Forex......, interest rates and commodities. If an investor positions himself on the (volatility) market within a long/short trading framework, he typically bets on a traditional mispricing arbitrage. However as this corresponds to a call spread with equal exercise prices, this strategy alone would not generate enough...

  14. It’s all about volatility of volatility

    DEFF Research Database (Denmark)

    Grassi, Stefano; Santucci de Magistris, Paolo

    2015-01-01

    for the realized volatility series. It emerges that during the recent financial crisis the relative weight of the daily component dominates over the monthly term. The estimates of the two factor stochastic volatility model suggest that the change in the dynamic structure of the realized volatility during...... the financial crisis is due to the increase in the volatility of the persistent volatility term. A set of Monte Carlo simulations highlights the robustness of the methodology adopted in tracking the dynamics of the parameters....

  15. 微波辅助衍生化-气相色谱法测定烟草中非挥发性有机酸%GC Determination of Non-volatile Organic Acids in Tobacco with Microwave Assisted Derivatization

    Institute of Scientific and Technical Information of China (English)

    蒋次清; 胡守毅; 李忠; 王璐; 王岚; 廖臻

    2011-01-01

    In the gas chromatographic determination of non-volatile ogranic acids in tobacco, a modification of the derivatization of the organic acid was made by reacting with a mixture of H2SO4 and CH3OH (1 +7) in a microoven under optimized working condition.The esterized solution was extracted with CH2Cl2, and the extract was evaporated to a volume of 2 mL.OneμL aliquot was taken for GC analysis.AC 20 capillary column and FID detector were used in the analysis, and pentanedioic acid was used as internal standard.Recovery and precision for 7 non-volatile organic acids were tested by standard addition method, values of recovery and RSD's (n=5) found were ranged from 97.5% to 103.3% and from 1.6% to 4.4% respectively.The proposed method was used in the determination of non-volatile organic acids in samples of flue-cured tobacco, cigarettes and hurley tobacco, giving results in consistency with the results obtained by the method reported in literature.%在气相色谱法测定烟草中非挥发性有机酸中,提出了用硫酸-甲醇(1+7)混合溶液作衍生试剂,在微波炉中于选定的条件下对所测定的有机酸进行衍生化.经酯化的溶液用二氯甲烷萃取,萃取液蒸缩至2 mL,分取1μL进样作气相色谱分析.测定中采用AC 20毛细管柱及火焰离子化(FID)检测器并用戊二酸作内标,对7种非挥发性有机酸用标准加入法作回收及精密度试验,测得回收率在97.5%~103.3%之间,相对标准偏差(n=5)在1.6%~4.4%之间.用所提出的方法测定了烤烟、卷烟及白肋烟样品中非挥发性有机酸,测定结果与文献方法的结果相符.

  16. Non-volatile memories

    CERN Document Server

    Lacaze, Pierre-Camille

    2014-01-01

    Written for scientists, researchers, and engineers, Non-volatile Memories describes the recent research and implementations in relation to the design of a new generation of non-volatile electronic memories. The objective is to replace existing memories (DRAM, SRAM, EEPROM, Flash, etc.) with a universal memory model likely to reach better performances than the current types of memory: extremely high commutation speeds, high implantation densities and retention time of information of about ten years.

  17. Quantitative determination of wine highly volatile sulfur compounds by using automated headspace solid-phase microextraction and gas chromatography-pulsed flame photometric detection. Critical study and optimization of a new procedure.

    Science.gov (United States)

    López, Ricardo; Lapeña, Ana Cristina; Cacho, Juan; Ferreira, Vicente

    2007-03-02

    The quantitative determination of wine volatile sulfur compounds by automated headspace solid-phase microextraction (HS-SPME) with a carboxen-polydimethylsiloxane (CAR-PDMS) fiber and subsequent gas chromatography-pulsed flame photometric detection (GC-PFPD) has been evaluated. The direct extraction of the sulfur compounds in 5 ml of wine has been found to suffer from matrix effects and short linear ranges, problems which could not be solved by the use of different internal standards or by multiple headspace SPME. These problems were attributed to saturation of the fiber and to competitive effects between analytes, internal standards and other wine volatiles. Another problem was the oxidation of analytes during the procedure. The reduction in sample volume by a factor 50 (0.1 ml diluted with water or brine) brought about a reduction in the amount of sulfur compounds taken in the fiber by a factor just 3.3. Consequently, a new procedure has been proposed. In a sealed vial containing 4.9 ml of saturated NaCl brine, the air is thoroughly displaced with nitrogen, and the wine (0.1 ml) and the internal standards (0.02 ml) are further introduced with a syringe through the vial septum. This sample is extracted at 35 degrees C for 20 min. This procedure makes a satisfactory determination possible of hydrogen sulfide, methanethiol, ethanethiol, dimethyl sulfide, diethyl sulfide and dimethyl disulfide. The linear dynamic ranges cover the normal ranges of occurrence of these analytes in wine with typical r2 between 0.9823 and 0.9980. Reproducibility in real samples ranges from 10 to 20% and repeatability is better than 10% in most cases. The method accuracy is satisfactory, with errors below 20% for hydrogen sulfide and mostly below 10% for the other compounds. The proposed method has been applied to the analysis of 34 Spanish wines.

  18. 气相色谱法测定室内空气中挥发性卤代烃%Determination of Volatile Halogenated Hydrocarbons in Indoor Air by Gas Chromatography

    Institute of Scientific and Technical Information of China (English)

    张倩; 张吉喆

    2014-01-01

    建立了活性炭吸附-溶剂解吸-气相色谱测定室内空气中7种挥发性卤代烃的分析方法。样品经活性炭采样管富集后,用二硫化碳解吸, Agilent HP-1色谱柱分离,使用带有电子捕获检测器的气相色谱仪测定,以保留时间定性,外标法定量。当采样体积为10 L 时,方法检出限范围是0.03~0.18 g/m3,加标回收率在72%~114%之间,相对标准偏差小于15%。结果表明,该方法可以应用于室内空气中痕量挥发性卤代烃样品的检测分析。%A novel determination method of seven volatile halogenated hydrocarbons in indoor air by activated charcoal adsorption/carbon disulfide desorption and gas chromatographic was developed. The samples were enriched by activated charcoal tube, desorbed with carbon disulfide. The target compounds were separated on an Agilent HP-1 chromatographic column and analyzed by gas chromatography with electron capture detector, qualitatived by retention time and qualified by the matrix-matched external standard method. When the sample volume was 10 L, method detection limits were in the range of 0.03~0.18 g/m3, respectively. The recoveries were in the range of 72%~114%, with relative standard deviation less than 15%. The method was handy, sensitive, accurate and suitable for the determination of volatile halogenated hydrocarbons in indoor at trace level.

  19. Study on determination of stress level by seismic stress drops and the stress axis deflections before and after large earthquakes

    Institute of Scientific and Technical Information of China (English)

    WAN Yong-ge

    2006-01-01

    To obtain the stress level at the earthquake source, this paper sets forth the solution of the stress magnitude at the earthquake source by seismic stress drop and the stress axis deflections before and after large earthquakes. The pre-seismic and post-seismic stress direction can be statistically determined by a large collection of foreshock and aftershock focal mechanism data while the stress drop can be determined through the source fracture inversion from seismic wave data or crust deformation data. The paper attempts to make a fundamental contribution to seismic dynamics.

  20. Low normal thyroid function as a determinant of increased large very low density lipoprotein particles

    NARCIS (Netherlands)

    van Tienhoven-Wind, Lynnda; Dullaart, Robin P. F.

    2015-01-01

    Objectives: Low-normal thyroid function may relate to increases in plasma cholesterol and triglycerides, but effects on lipoprotein subfractions are largely unknown. Associations of alterations in lipoprotein metabolism and functionality with low-normal thyroid function could be more pronounced in T

  1. 12 CFR 360.9 - Large-bank deposit insurance determination modernization.

    Science.gov (United States)

    2010-01-01

    ... market discipline, ensure equitable treatment of depositors at different institutions and reduce the FDIC... section for a covered institution that: Has a composite rating of 3, 4, or 5 under the Uniform Financial... operations of a large insured depository institution (defined as a “Covered Institution”) to...

  2. Moisture and nutrients determine the distribution and richness of India's large herbivore species assemblage

    NARCIS (Netherlands)

    Ahrestani, F.S.; Heitkonig, I.M.A.; Langevelde, van F.; Vaidyanathan, S.; Madhusudan, M.D.; Prins, H.H.T.

    2011-01-01

    The goal of this study was to test whether body-mass based foraging principles, guided by plant available moisture (PAM) and plant available nutrients (PAN), could explain large mammalian herbivore species distribution and richness in India. We tested (1) whether the occurrence of larger-bodied

  3. Patch densities determines movement patterns and foraging efficiency of large herbivores

    NARCIS (Netherlands)

    Knegt, de H.J.; Hengeveld, G.M.; Langevelde, van F.; Boer, de W.F.; Kirkman, K.P.

    2007-01-01

    Few experimental studies have tested theoretical predictions regarding the movement strategies of large herbivores and their consequences for foraging efficiency. We therefore analyze how the movement and foraging behavior of goats are related to patch density, with patches being trees and bushes. W

  4. A method of determining nonlinear large strain consolidation parameters of dredged clays

    Directory of Open Access Journals (Sweden)

    Yu-peng CAO

    2014-04-01

    Full Text Available A method of obtaining the large strain consolidation parameters of dredged clays considering the influence of the initial water content is investigated in this study. According to the test results of remolded clays with high initial water contents reported by Hong et al. (2010, a relationship between the void ratio (e and effective stress (σ' is established. Furthermore, based on the available permeability data from the literature, a new relationship between the permeability coefficient (k and the ratio (e/eL of the void ratio to the void ratio at the liquid limit (eL is proposed. The new proposed expression considering the initial water content improves the e-k equation established by Nagaraj et al. (1994. Finally, the influence of the initial void ratio and effective stress on the large strain consolidation coefficient g(e defined by Gibson et al. (1981 and k/(1+e in large strain analysis is discussed. The results show that, under a constant effective stress, the value of k/(1+e increases with the initial void ratio. The large strain consolidation coefficient shows the law of segmentation change, which decreases with the increase of the effective stress when the effective stress is less than the remolded yield stress, but increases rapidly with the effective stress when the effective stress is larger than the remolded yield stress.

  5. Low normal thyroid function as a determinant of increased large very low density lipoprotein particles

    NARCIS (Netherlands)

    van Tienhoven-Wind, Lynnda; Dullaart, Robin P. F.

    Objectives: Low-normal thyroid function may relate to increases in plasma cholesterol and triglycerides, but effects on lipoprotein subfractions are largely unknown. Associations of alterations in lipoprotein metabolism and functionality with low-normal thyroid function could be more pronounced in

  6. Analyzing the Actual Execution of a Large Software-Intensive System for Determining Dependencies

    NARCIS (Netherlands)

    Callo Arias, Trosky B.; Avgeriou, Paris; America, Pierre; Hassan, AE; Zaidman, A; DiPenta, M

    2008-01-01

    In this paper, we present a dynamic analysis approach to increase the understandability of a large software-intensive system, more particularly to enable the identification of dependencies between its execution entities. This approach analyzes the execution of a software system in a top-down fashion

  7. Variation of volatile compounds among wheat varieties and landraces.

    Science.gov (United States)

    Starr, G; Petersen, M A; Jespersen, B M; Hansen, Å S

    2015-05-01

    Analysis of volatile compounds was performed on 81 wheat varieties and landraces, grown under controlled greenhouse conditions, in order to investigate the possibility of differentiating wheat varieties according to their volatile compound profiles. Volatile compounds from wheat samples were extracted by dynamic headspace extraction and analysed by gas chromatography-mass spectrometry. Seventy-two volatile compounds were identified in the wheat samples. Multivariate analysis of the data showed a large diversity in volatile profiles between samples. Differences occurred between samples from Austria compared to British, French and Danish varieties. Landraces were distinguishable from modern varieties and they were characterised by higher averaged peak areas for esters, alcohols, and some furans. Modern varieties were characterised by higher averaged peak areas for terpenes, pyrazines and straight-chained aldehydes. Differences in volatile profiles are demonstrated between wheat samples for the first time, based on variety. These results are significant to plant breeders and commercial users of wheat.

  8. 40 CFR 60.452 - Standard for volatile organic compounds.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 6 2010-07-01 2010-07-01 false Standard for volatile organic compounds. 60.452 Section 60.452 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR... Industrial Surface Coating: Large Appliances § 60.452 Standard for volatile organic compounds. On or...

  9. Viscosity methods for multiscale financial models with stochastic volatility

    OpenAIRE

    Bardi, Martino; Cesaroni, Annalisa; Ghilli, Daria; Scotti, Andrea

    2014-01-01

    Parallel session; International audience; Introduction on models Financial models and stochastic volatility, Gaussian or with jumps Fast stochastic volatility Part 1 Control systems with random parameters and multiple scales The Hamilton-Jacobi-Bellman approach to Singular Perturbations I Tools I Assumptions I A convergence result Applications to finance Part 2 Large deviations for small time to maturity: see also Daria Ghilli's poster tomorrow

  10. Oil and stock market volatility: A multivariate stochastic volatility perspective

    Energy Technology Data Exchange (ETDEWEB)

    Vo, Minh, E-mail: minh.vo@metrostate.edu

    2011-09-15

    This paper models the volatility of stock and oil futures markets using the multivariate stochastic volatility structure in an attempt to extract information intertwined in both markets for risk prediction. It offers four major findings. First, the stock and oil futures prices are inter-related. Their correlation follows a time-varying dynamic process and tends to increase when the markets are more volatile. Second, conditioned on the past information, the volatility in each market is very persistent, i.e., it varies in a predictable manner. Third, there is inter-market dependence in volatility. Innovations that hit either market can affect the volatility in the other market. In other words, conditioned on the persistence and the past volatility in their respective markets, the past volatility of the stock (oil futures) market also has predictive power over the future volatility of the oil futures (stock) market. Finally, the model produces more accurate Value-at-Risk estimates than other benchmarks commonly used in the financial industry. - Research Highlights: > This paper models the volatility of stock and oil futures markets using the multivariate stochastic volatility model. > The correlation between the two markets follows a time-varying dynamic process which tends to increase when the markets are more volatile. > The volatility in each market is very persistent. > Innovations that hit either market can affect the volatility in the other market. > The model produces more accurate Value-at-Risk estimates than other benchmarks commonly used in the financial industry.

  11. Irrigation as a Determinant of Social Capital in India: A Large-Scale Survey Analysis

    OpenAIRE

    von Carnap-Bornheim, Tillmann

    2016-01-01

    Practicing agriculture requires organisation and coordination. To analyse the extent to which differences in agricultural practices can account for variation in social capital, a large survey containing indicators of social capital is combined with detailed agricultural statistics. The main factor under analysis is irrigation, together with prevalent grain sorts, thereby building on prior research. The richness of the datasets allows to explore various dimensions of social capital in geograph...

  12. Automated determination of magnitude and source length of large earthquakes using backprojection and P wave amplitudes

    Science.gov (United States)

    Wang, Dun; Kawakatsu, Hitoshi; Zhuang, Jiancang; Mori, Jim; Maeda, Takuto; Tsuruoka, Hiroshi; Zhao, Xu

    2017-06-01

    Fast estimates of magnitude and source extent of large earthquakes are fundamental for disaster mitigation. However, resolving these estimates within 10-20 min after origin time remains challenging. Here we propose a robust algorithm to resolve magnitude and source length of large earthquakes using seismic data recorded by regional arrays and global stations. We estimate source length and source duration by backprojecting seismic array data. Then the source duration and the maximum amplitude of the teleseismic P wave displacement waveforms are used jointly to estimate magnitude. We apply this method to 74 shallow earthquakes that occurred within epicentral distances of 30-85° to Hi-net (2004-2014). The estimated magnitudes are similar to moment magnitudes estimated from W-phase inversions (U.S. Geological Survey), with standard deviations of 0.14-0.19 depending on the global station distributions. Application of this method to multiple regional seismic arrays could benefit tsunami warning systems and emergency response to large global earthquakes.

  13. Determinants of Police Strength in Large U.S. Cities during the 1990s: A Fixed-Effects Panel Analysis

    Science.gov (United States)

    McCarty, William P.; Ren, Ling; Zhao, Jihong

    2012-01-01

    The 1990s represented a unique decade in which to analyze the determinants of police strength in the United States. This decade was a time in which crime initially increased, then substantially decreased. Furthermore, this decade also was characterized by increases in the minority population throughout large American cities. Finally, the 1990s…

  14. 78 FR 3916 - Certain Welded Large Diameter Line Pipe From Japan; Notice of Commission Determination To Conduct...

    Science.gov (United States)

    2013-01-17

    ... From the Federal Register Online via the Government Publishing Office INTERNATIONAL TRADE COMMISSION Certain Welded Large Diameter Line Pipe From Japan; Notice of Commission Determination To Conduct... will be established and announced at a later date. For further information concerning the conduct of...

  15. Thickness determination of large-area films of yttria-stabilized zirconia produced by pulsed laser deposition

    DEFF Research Database (Denmark)

    Pryds, N.; Christensen, Bo Toftmann; Bilde-Sørensen, Jørgen;

    2006-01-01

    Films of yuria-stabilized zirconia (YSZ) on a polished silicon substrate of diameter up to 125 mm have been produced in a large-area pulsed laser deposition (PLD) setup under typical PLD conditions. The film thickness over the full film area has been determined by energy-dispersive Xray spectrome...

  16. A review of challenges to determining and demonstrating efficiency of large fire management

    Science.gov (United States)

    Matthew P. Thompson; Francisco Rodriguez y Silva; David E. Calkin; Michael S. Hand

    2017-01-01

    Characterising the impacts of wildland fire and fire suppression is critical information for fire management decision-making. Here, we focus on decisions related to the rare larger and longer-duration fire events, where the scope and scale of decision-making can be far broader than initial response efforts, and where determining and demonstrating efficiency of...

  17. Volatile halogenated hydrocarbons in foods

    Energy Technology Data Exchange (ETDEWEB)

    Miyahara, Makoto; Toyoda, Masatake; Saito, Yukio [National Institute of Health Services, Tokyo (Japan)] [and others

    1995-02-01

    Volatile halogenated organic compounds were determined in foods. Statistical treatment of the data for 13 sampled from 20 families living in suburban Tokyo (Saitama prefecture) indicated that the foods were contaminated by water pollution and/or substances introduced by the process of food production. Butter and margarine were contaminated by chlorinated ethylene, ethane, and related compounds released by dry cleaning and other operations. Soybean sprouts and tofu (soybean curd) contained chloroform and related trihalomethanes absorbed during the production process. 27 refs., 6 figs., 5 tabs.

  18. Volatility transmission and volatility impulse response functions in European electricity forward markets

    Energy Technology Data Exchange (ETDEWEB)

    Le Pen, Yannick [Institut d' Economie et de Management de Nantes - IAE, Universite de Nantes, Chemin de la Censive du Tertre, BP 52231, 44322 Nantes cedex 3 (France); Sevi, Benoit [Universite d' Angers (GRANEM), Faculte de Droit, Economie et Gestion, Universite d' Angers, 13 allee Francois Mitterrand, BP 13633, 49036 Angers cedex 01 (France)

    2010-07-15

    Using daily data from March 2001 to June 2005, we estimate a VAR-BEKK model and find evidence of return and volatility spillovers between the German, the Dutch and the British forward electricity markets. We apply Hafner and Herwartz [2006, Journal of International Money and Finance 25, 719-740] Volatility Impulse Response Function (VIRF) to quantify the impact of shock on expected conditional volatility. We observe that a shock has a high positive impact only if its size is large compared to the current level of volatility. The impact of shocks are usually not persistent, which may be a consequence of the non-storability of power. Finally, we estimate the density of the VIRF at different forecast horizons. These fitted distributions are asymmetric and show that large increases in expected conditional volatilities are possible even if their probability is low. These results have interesting implications for market participants whose risk management policy depends on option prices which themselves depend on the characteristics of volatility. (author)

  19. Determination of Non-Universal Supergravity Models at the Large Hadron Collider

    CERN Document Server

    Dutta, Bhaskar; Krislock, Abram; Kolev, Nikolay; Oh, Youngdo

    2010-01-01

    We examine a well motivated non-universal supergravity model where the Higgs boson masses are not unified with the other scalars at the grand unified scale at the LHC. The dark matter content can easily be satisfied in this model by having a larger Higgsino component in the lightest neutralino. Typical final states in such a scenario at the LHC involve W bosons. We develop a bi-event subtraction technique to remove a huge combinatorial background to identify W -> jj decays. This is also a key technique to reconstruct supersymmetric particle masses in order to determine the model parameters. With the model parameters, we find that the dark matter content of the universe can be determined in agreement with existing experimental results.

  20. A method for determining Am-241 activity for large area contamination.

    Science.gov (United States)

    Wilhelm, Emilien; Arbor, Nicolas; Gutierrez, Sébastien; Ménard, Stéphanie; Nourreddine, Abdel-Mjid

    2017-01-01

    Airborne gamma-ray spectrometry system HELINUC™ is used for different missions. Although well-developed for estimation of high energy emitters' activity, it is rarely used for low energy emitters. A new method for the determination of Am-241 activity over extended sites based both on statistical analysis of spectra and deconvolution of Am-241 signal with a reference library is presented. Results show a lowering of the detection threshold and a good agreement with ground level measurements.

  1. Determinants and Role of Trust in E-Business: A Large Scale Empirical Study

    OpenAIRE

    Sultan, Fareena.; Urban, Glen; Shankar, Venkatesh; Bart, Iakov

    2003-01-01

    This research investigates the determinants and role of consumer trust in e-business. It examines consumer perceptions of trust in a Web site and addresses the following key research questions: What factors influence consumer trust in a Web site and what specific Web site trust cues are associated with these factors? How does trust affect consumer behavioral intent on a Web site? To address these questions, we develop a conceptual model that links consumer perceptions of Web site characterist...

  2. Technical Note: The determination of enclosed water volume in large flexible-wall mesocosms "KOSMOS"

    Directory of Open Access Journals (Sweden)

    J. Czerny

    2013-03-01

    Full Text Available The volume of water enclosed inside flexible-wall mesocosm bags is hard to estimate using geometrical calculations and can be strongly variable among bags of the same dimensions. Here we present a method for precise water volume determination in mesocosms using salinity as a tracer. Knowledge of the precise volume of water enclosed allows establishment of exactly planned treatment concentrations and calculation of elemental budgets.

  3. Determination of boron over a large dynamic range by prompt-gamma activation analysis

    Energy Technology Data Exchange (ETDEWEB)

    Harrison, R.K. [University of Texas at Austin, Nuclear Engineering Teaching Lab., Pickle Research Campus, R-9000 Austin, TX 78712 (United States); Landsberger, S. [University of Texas at Austin, Nuclear Engineering Teaching Lab., Pickle Research Campus, R-9000 Austin, TX 78712 (United States)], E-mail: s.landsberger@mail.utexas.edu

    2009-02-15

    An evaluation of the PGAA method for the determination of boron across a wide dynamic range of concentrations was performed for trace levels up to 5 wt.% boron. This range encompasses a transition from neutron transparency to significant self- shielding conditions. To account for self-shielding, several PGAA techniques were employed. First, a calibration curve was developed in which a set of boron standards was tested and the count rate to boron mass curve was determined. This set of boron measurements was compared with an internal standard self-shielding correction method and with a method for determining composition using PGAA peak ratios. The advantages and disadvantages of each method are analyzed. The boron concentrations of several laboratory-grade chemicals and standard reference materials were measured with each method and compared. The evaluation of the boron content of nanocrystalline transition metals prepared with a boron-containing reducing agent was also performed with each of the methods tested. Finally, the k{sub 0} method was used for non-destructive measurement of boron in catalyst materials for the characterization of new non-platinum fuel cell catalysts.

  4. Stochastic volatility of the futures prices of emission allowances: A Bayesian approach

    Science.gov (United States)

    Kim, Jungmu; Park, Yuen Jung; Ryu, Doojin

    2017-01-01

    Understanding the stochastic nature of the spot volatility of emission allowances is crucial for risk management in emissions markets. In this study, by adopting a stochastic volatility model with or without jumps to represent the dynamics of European Union Allowances (EUA) futures prices, we estimate the daily volatilities and model parameters by using the Markov Chain Monte Carlo method for stochastic volatility (SV), stochastic volatility with return jumps (SVJ) and stochastic volatility with correlated jumps (SVCJ) models. Our empirical results reveal three important features of emissions markets. First, the data presented herein suggest that EUA futures prices exhibit significant stochastic volatility. Second, the leverage effect is noticeable regardless of whether or not jumps are included. Third, the inclusion of jumps has a significant impact on the estimation of the volatility dynamics. Finally, the market becomes very volatile and large jumps occur at the beginning of a new phase. These findings are important for policy makers and regulators.

  5. Understanding Interest Rate Volatility

    DEFF Research Database (Denmark)

    Volker, Desi

    This thesis is the result of my Ph.D. studies at the Department of Finance of the Copenhagen Business School. It consists of three essays covering topics related to the term structure of interest rates, monetary policy and interest rate volatility. The rst essay, \\Monetary Policy Uncertainty...... and Interest Rates", examines the role of monetary policy uncertainty on the term structure of interest rates. The second essay, \\A Regime-Switching A ne Term Structure Model with Stochastic Volatility" (co-authored with Sebastian Fux), investigates the ability of the class of regime switching models...... with and without stochastic volatility to capture the main stylized features of U.S. interest rates. The third essay, \\Variance Risk Premia in the Interest Rate Swap Market", investigates the time-series and cross-sectional properties of the compensation demanded for holding interest rate variance risk. The essays...

  6. Volatiles in protoplanetary disks

    CERN Document Server

    Pontoppidan, Klaus M; Bergin, Edwin A; Brittain, Sean; Marty, Bernard; Mousis, Olvier; Oberg, Karin L

    2014-01-01

    Volatiles are compounds with low sublimation temperatures, and they make up most of the condensible mass in typical planet-forming environments. They consist of relatively small, often hydrogenated, molecules based on the abundant elements carbon, nitrogen and oxygen. Volatiles are central to the process of planet formation, forming the backbone of a rich chemistry that sets the initial conditions for the formation of planetary atmospheres, and act as a solid mass reservoir catalyzing the formation of planets and planetesimals. This growth has been driven by rapid advances in observations and models of protoplanetary disks, and by a deepening understanding of the cosmochemistry of the solar system. Indeed, it is only in the past few years that representative samples of molecules have been discovered in great abundance throughout protoplanetary disks - enough to begin building a complete budget for the most abundant elements after hydrogen and helium. The spatial distributions of key volatiles are being mapped...

  7. Stochastic volatility selected readings

    CERN Document Server

    Shephard, Neil

    2005-01-01

    Neil Shephard has brought together a set of classic and central papers that have contributed to our understanding of financial volatility. They cover stocks, bonds and currencies and range from 1973 up to 2001. Shephard, a leading researcher in the field, provides a substantial introduction in which he discusses all major issues involved. General Introduction N. Shephard. Part I: Model Building. 1. A Subordinated Stochastic Process Model with Finite Variance for Speculative Prices, (P. K. Clark). 2. Financial Returns Modelled by the Product of Two Stochastic Processes: A Study of Daily Sugar Prices, 1961-7, S. J. Taylor. 3. The Behavior of Random Variables with Nonstationary Variance and the Distribution of Security Prices, B. Rosenberg. 4. The Pricing of Options on Assets with Stochastic Volatilities, J. Hull and A. White. 5. The Dynamics of Exchange Rate Volatility: A Multivariate Latent Factor ARCH Model, F. X. Diebold and M. Nerlove. 6. Multivariate Stochastic Variance Models. 7. Stochastic Autoregressive...

  8. On determining the large-scale ocean circulation from satellite altimetry

    Science.gov (United States)

    Tai, C.-K.

    1983-01-01

    It is contended that a spherical harmonic expansion of the difference between the altimeter-derived mean sea surface and the geoid estimate should reveal the large-scale circulation of the ocean surface layer when the low-degree terms are examined. Methods based on this principle are proposed and partially demonstrated over the Pacific Ocean with the aid of the mean sea surface derived from the Seasat altimeter and the Goddard Earth Model 9 earth gravity model. The preliminary results reveal a well-defined clockwise gyre in the North Pacific and a much less well defined counterclockwise gyre in the South Pacific. When the dynamic topography thus obtained is compared with Wyrtki's (1975) dynamic topography derived from hydrographic data, the agreement is found to be within the limit of geoid uncertainties and satellite orbital errors.

  9. Light yield determination in large sodium iodide detectors applied in the search for dark matter

    Science.gov (United States)

    Oliván, M. A.; Amaré, J.; Cebrián, S.; Cuesta, C.; García, E.; Martínez, M.; Ortigoza, Y.; Ortiz de Solórzano, A.; Pobes, C.; Puimedón, J.; Sarsa, M. L.; Villar, J. A.; Villar, P.

    2017-07-01

    Application of NaI(Tl) detectors in the search for galactic dark matter particles through their elastic scattering off the target nuclei is well motivated because of the long standing DAMA/LIBRA highly significant positive result on annual modulation, still requiring confirmation. For such a goal, it is mandatory to reach very low threshold in energy (at or below the keV level), very low radioactive background (at a few counts/keV/kg/day), and high detection mass (at or above the 100 kg scale). One of the most relevant technical issues is the optimization of the crystal intrinsic scintillation light yield and the efficiency of the light collecting system for large mass crystals. In the frame of the ANAIS (Annual modulation with NaI Scintillators) dark matter search project large NaI(Tl) crystals from different providers coupled to two photomultiplier tubes (PMTs) have been tested at the Canfranc Underground Laboratory. In this paper we present the estimates of the NaI(Tl) scintillation light collected using full-absorption peaks at very low energy from external and internal sources emitting gammas/electrons, and single-photoelectron events populations selected by using very low energy pulses tails. Outstanding scintillation light collection at the level of 15 photoelectrons/keV can be reported for the final design and provider chosen for ANAIS detectors. Taking into account the quantum efficiency of the PMT units used, the intrinsic scintillation light yield in these NaI(Tl) crystals is above 40 photons/keV for energy depositions in the range from 3 up to 25 keV. This very high light output of ANAIS crystals allows triggering below 1 keV, which is very important in order to increase the sensitivity in the direct detection of dark matter.

  10. Changes in dark chocolate volatiles during storage.

    Science.gov (United States)

    Nightingale, Lia M; Cadwallader, Keith R; Engeseth, Nicki J

    2012-05-09

    Chocolate storage is critical to the quality of the final product. Inadequate storage, especially with temperature fluctuations, may lead to a change in crystal structure, which may eventually cause fat bloom. Bloom is the main cause of quality loss in the chocolate industry. The impact of various storage conditions on the flavor quality of dark chocolate was determined. Dark chocolate was stored in different conditions leading to either fat or sugar bloom and analyzed at 0, 4, and 8 weeks of storage. Changes in chocolate flavor were determined by volatile analysis and descriptive sensory evaluation. Results were analyzed by analysis of variance (ANOVA), cluster analysis, principal component analysis (PCA), and linear partial least-squares regression analysis (PLS). Volatile concentration and loss were significantly affected by storage conditions. Chocolates stored at high temperature were the most visually and texturally compromised, but volatile concentrations were affected the least, whereas samples stored at ambient, frozen, and high relative humidity conditions had significant volatile loss during storage. It was determined that high-temperature storage caused a change in crystal state due to the polymorphic shift to form VI, leading to an increase in sample hardness. Decreased solid fat content (SFC) during high-temperature storage increased instrumentally determined volatile retention, although no difference was detected in chocolate flavor during sensory analysis, possibly due to instrumental and sensory sampling techniques. When all instrumental and sensory data had been taken into account, the storage condition that had the least impact on texture, surface roughness, grain size, lipid polymorphism, fat bloom formation, volatile concentrations, and sensory attributes was storage at constant temperature and 75% relative humidity.

  11. Method to Determine Appropriate Source Models of Large Earthquakes Including Tsunami Earthquakes for Tsunami Early Warning in Central America

    Science.gov (United States)

    Tanioka, Yuichiro; Miranda, Greyving Jose Arguello; Gusman, Aditya Riadi; Fujii, Yushiro

    2017-08-01

    Large earthquakes, such as the Mw 7.7 1992 Nicaragua earthquake, have occurred off the Pacific coasts of El Salvador and Nicaragua in Central America and have generated distractive tsunamis along these coasts. It is necessary to determine appropriate fault models before large tsunamis hit the coast. In this study, first, fault parameters were estimated from the W-phase inversion, and then an appropriate fault model was determined from the fault parameters and scaling relationships with a depth dependent rigidity. The method was tested for four large earthquakes, the 1992 Nicaragua tsunami earthquake (Mw7.7), the 2001 El Salvador earthquake (Mw7.7), the 2004 El Astillero earthquake (Mw7.0), and the 2012 El Salvador-Nicaragua earthquake (Mw7.3), which occurred off El Salvador and Nicaragua in Central America. The tsunami numerical simulations were carried out from the determined fault models. We found that the observed tsunami heights, run-up heights, and inundation areas were reasonably well explained by the computed ones. Therefore, our method for tsunami early warning purpose should work to estimate a fault model which reproduces tsunami heights near the coast of El Salvador and Nicaragua due to large earthquakes in the subduction zone.

  12. Pricing Volatility of Stock Returns with Volatile and Persistent Components

    DEFF Research Database (Denmark)

    Zhu, Jie

    2009-01-01

    This paper introduces a two-component volatility model based on first moments of both components to describe the dynamics of speculative return volatility. The two components capture the volatile and the persistent part of volatility, respectively. The model is applied to 10 Asia-Pacific stock...... markets. Their in-mean effects on returns are tested. The empirical results show that the persistent component is much more important for the volatility dynamic process than is the volatile component. However, the volatile component is found to be a significant pricing factor of asset returns for most...... markets. A positive or risk-premium effect exists between the return and the volatile component, yet the persistent component is not significantly priced for the return dynamic process....

  13. Treasury bond volatility and uncertainty about monetary policy

    NARCIS (Netherlands)

    Arnold, I.J.M.; Vrugt, E.B.

    2010-01-01

    We show that dispersion-based uncertainty about the future course of monetary policy is the single most important determinant of Treasury bond volatility across all maturities. The link between Treasury bond volatility and uncertainty about macroeconomic variables is much stronger than for the more

  14. Treasury bond volatility and uncertainty about monetary policy

    NARCIS (Netherlands)

    Arnold, I.J.M.; Vrugt, E.B.

    2010-01-01

    We show that dispersion-based uncertainty about the future course of monetary policy is the single most important determinant of Treasury bond volatility across all maturities. The link between Treasury bond volatility and uncertainty about macroeconomic variables is much stronger than for the more

  15. Evaluation of Immunoassay for the Determination of Pesticides at a Large-Scale Groundwater Contamination Site

    Science.gov (United States)

    Dombrowski, T.R.; Thurman, E.M.; Mohrman, G.B.

    1996-01-01

    Pesticide concentrations in ground water at Rocky Mountain Arsenal (RMA) near Denver, Colorado, were determined using solid-phase extraction (SPE) gas chromatography/mass spectrometry (GC/MS) procedures and enzyme-linked immunosorbent assay (ELISA) for cyclodiene insecticides and triazine herbicides. Matrix interferences resulted in inconclusive results for some GC/MS analyses due to baseline disturbances and co-elution, but ELISA analyses consistently gave definitive results in a minimum amount of time. ELISA was used initially as a screening method, and pesticide concentrations and plume extents identified by ELISA were confirmed by SPE-GC/MS. A high degree of correlation was seen between results from GC/MS and ELISA methods for the triazine herbicides (correlation coefficient (R2) = 0.99). All areas with high pesticide concentrations were found to be within the boundaries of RMA.

  16. A modified oxidative microcoulometric method for determination of sulphur in hydrocarbons containing large amounts of chlorine.

    Science.gov (United States)

    Cedergren, A

    1977-01-01

    The oxidative coulometric method for trace sulphur determinations has been modified and a procedure is described which includes the elimination of the interferences caused by chlorine whilst retaining a high recovery of sulphur. The liquid hydrocarbon sample is combusted in an excess of oxygen at 1000 K followed by dilution with a proper flow of carbon monoxide at 1300 K. In this way the partial pressure of oxygen is kept small and the interfering chlorine compounds are effectively converted into hydrogen chloride which does not interfere with the coulometric titration. A recovery of sulphur of 96 +/- 1% was found for thiophene in mixtures of chlorobenzene (0-10%) and cyclohexane, thus indicating the absence of significant interference.

  17. DNA Sequence Determination by Hybridization: A Strategy for Efficient Large-Scale Sequencing

    Science.gov (United States)

    Drmanac, R.; Drmanac, S.; Strezoska, Z.; Paunesku, T.; Labat, I.; Zeremski, M.; Snoddy, J.; Funkhouser, W. K.; Koop, B.; Hood, L.; Crkvenjakov, R.

    1993-06-01

    The concept of sequencing by hybridization (SBH) makes use of an array of all possible n-nucleotide oligomers (n-mers) to identify n-mers present in an unknown DNA sequence. Computational approaches can then be used to assemble the complete sequence. As a validation of this concept, the sequences of three DNA fragments, 343 base pairs in length, were determined with octamer oligonucleotides. Possible applications of SBH include physical mapping (ordering) of overlapping DNA clones, sequence checking, DNA fingerprinting comparisons of normal and disease-causing genes, and the identification of DNA fragments with particular sequence motifs in complementary DNA and genomic libraries. The SBH techniques may accelerate the mapping and sequencing phases of the human genome project.

  18. Members of a large retroposon family are determinants of post-transcriptional gene expression in Leishmania.

    Directory of Open Access Journals (Sweden)

    Frédéric Bringaud

    2007-09-01

    Full Text Available Trypanosomatids are unicellular protists that include the human pathogens Leishmania spp. (leishmaniasis, Trypanosoma brucei (sleeping sickness, and Trypanosoma cruzi (Chagas disease. Analysis of their recently completed genomes confirmed the presence of non-long-terminal repeat retrotransposons, also called retroposons. Using the 79-bp signature sequence common to all trypanosomatid retroposons as bait, we identified in the Leishmania major genome two new large families of small elements--LmSIDER1 (785 copies and LmSIDER2 (1,073 copies--that fulfill all the characteristics of extinct trypanosomatid retroposons. LmSIDERs are approximately 70 times more abundant in L. major compared to T. brucei and are found almost exclusively within the 3'-untranslated regions (3'UTRs of L. major mRNAs. We provide experimental evidence that LmSIDER2 act as mRNA instability elements and that LmSIDER2-containing mRNAs are generally expressed at lower levels compared to the non-LmSIDER2 mRNAs. The considerable expansion of LmSIDERs within 3'UTRs in an organism lacking transcriptional control and their role in regulating mRNA stability indicate that Leishmania have probably recycled these short retroposons to globally modulate the expression of a number of genes. To our knowledge, this is the first example in eukaryotes of the domestication and expansion of a family of mobile elements that have evolved to fulfill a critical cellular function.

  19. Determination of reddening and age for ten Large Magellanic Cloud star clusters from integrated spectroscopy

    CERN Document Server

    Ahumada, Andrea V; Clariá, Juan J; Oddone, Mónica A; Palma, Tali

    2016-01-01

    We present flux-calibrated integrated spectra in the optical range (3700-6800 \\AA) obtained at Complejo Astron\\'omico El Leoncito (CASLEO, Argentina) for a sample of 10 concentrated star clusters belonging to the Large Magellanic Cloud (LMC). No previous data exist for two of these objects (SL 142 and SL 624), while most of the remaining clusters have been only poorly studied. We derive simultaneously foreground $E(B-V)$ reddening values and ages for the cluster sample by comparing their integrated spectra with template LMC cluster spectra and with two different sets of simple stellar population models. Cluster reddening values and ages are also derived from both available interstellar extinction maps and by using diagnostic diagrams involving the sum of equivalent widths of some selected spectral features and their calibrations with age, respectively. For the studied sample, we derive ages between 1 Myr and 240 Myr. In an effort to create a spectral library at the LMC metallicity level with several clusters ...

  20. Determination of Reddening and Age for Ten Large Magellanic Cloud Star Clusters from Integrated Spectroscopy

    Science.gov (United States)

    Ahumada, Andrea V.; Vega, Luis R.; Clariá, Juan J.; Oddone, Mónica A.; Palma, Tali

    2016-09-01

    We present flux-calibrated integrated spectra in the optical range (3700-6800 Å) obtained at Complejo Astronómico El Leoncito (CASLEO, Argentina) for a sample of 10 concentrated star clusters belonging to the Large Magellanic Cloud (LMC). No previous data exist for two of these objects (SL 142 and SL 624), while most of the remaining clusters have been only poorly studied. We derive simultaneously foreground E(B - V) reddening values and ages for the cluster sample by comparing their integrated spectra with template LMC cluster spectra and with two different sets of simple stellar population models. Cluster reddening values and ages are also derived from both available interstellar extinction maps and by using diagnostic diagrams involving the sum of equivalent widths of some selected spectral features and their calibrations with age, respectively. For the studied sample, we derive ages between 1 Myr and 240 Myr. In an effort to create a spectral library at the LMC metallicity level with several clusters per age range, the cluster sample presented here stands out as a useful complement to previous ones.

  1. Volatile and semivolatile organic compounds in laboratory peat fire emissions

    Science.gov (United States)

    George, Ingrid J.; Black, Robert R.; Geron, Chris D.; Aurell, Johanna; Hays, Michael D.; Preston, William T.; Gullett, Brian K.

    2016-05-01

    In this study, volatile and semi-volatile organic compound (VOCs and SVOCs) mass emission factors were determined from laboratory peat fire experiments. The peat samples originated from two National Wildlife Refuges on the coastal plain of North Carolina, U.S.A. Gas- and particle-phase organic compounds were quantified by gas chromatography-mass spectrometry and by high pressure liquid chromatography. Hazardous air pollutants (HAPs) accounted for a large fraction (∼60%) of the speciated VOC emissions from peat burning, including large contributions of acetaldehyde, formaldehyde, benzene, toluene, and chloromethane. In the fine particle mass (PM2.5), the following organic compound classes were dominant: organic acids, levoglucosan, n-alkanes, and n-alkenes. Emission factors for the organic acids in PM2.5 including n-alkanoic acids, n-alkenoic acids, n-alkanedioic acids, and aromatic acids were reported for the first time for peat burning, representing the largest fraction of organic carbon (OC) mass (11-12%) of all speciated compound classes measured in this work. Levoglucosan contributed to 2-3% of the OC mass, while methoxyphenols represented 0.2-0.3% of the OC mass on a carbon mass basis. Retene was the most abundant particulate phase polycyclic aromatic hydrocarbon (PAH). Total HAP VOC and particulate PAH emissions from a 2008 peat wildfire in North Carolina were estimated, suggesting that peat fires can contribute a large fraction of state-wide HAP emissions.

  2. Pricing Volatility of Stock Returns with Volatile and Persistent Components

    DEFF Research Database (Denmark)

    Zhu, Jie

    In this paper a two-component volatility model based on the component's first moment is introduced to describe the dynamic of speculative return volatility. The two components capture the volatile and persistent part of volatility respectively. Then the model is applied to 10 Asia-Pacific stock m......, a positive or risk-premium effect exists between return and the volatile component, yet the persistent component is not significantly priced for return dynamic process.......In this paper a two-component volatility model based on the component's first moment is introduced to describe the dynamic of speculative return volatility. The two components capture the volatile and persistent part of volatility respectively. Then the model is applied to 10 Asia-Pacific stock...... markets. Their in-mean effects on return are also tested. The empirical results show that the persistent component accounts much more for volatility dynamic process than the volatile component. However the volatile component is found to be a significant pricing factor of asset returns for most markets...

  3. Determination of semi-volatile and particle-associated polycyclic aromatic hydrocarbons in Stockholm air with emphasis on the highly carcinogenic dibenzopyrene isomers

    Science.gov (United States)

    Masala, Silvia; Lim, Hwanmi; Bergvall, Christoffer; Johansson, Christer; Westerholm, Roger

    2016-09-01

    The concentrations of polycyclic aromatic hydrocarbons (PAHs) have been determined in the gaseous phase and in various particulate matter (PM) size fractions at different locations in and outside of Stockholm, Sweden, representative of street level, urban and rural background. The focus has been on the seldom determined but highly carcinogenic dibenzopyrene isomers (DBPs) dibenzo[a,l]pyrene, dibenzo[a,e]pyrene, dibenzo[a,i]pyrene and dibenzo[a,h]pyrene. PAHs with 3 rings were found to be mainly associated with the vapor phase (>90%) whereas PAHs with 5-6 rings were mostly associated with particulate matter (>92%) and the 4-ringed PAHs partitioned between the two phases. PAH abundance was determined to be in the order street level > urban background > rural background with the PM10 street level 2010 mean of benzo[a]pyrene (B[a]P) reaching 0.24 ng/m3, well below the EU annual limit value of 1 ng/m3. In addition, higher PAH concentrations were found in the sub-micron particle fraction (PM1) as compared to the super-micron fraction (PM1-10) with the abundance in PM1 varying between 57 and 86% of the total PAHs. The B[a]P equivalent concentrations derived for DB[a,l]P and total DBPs exceeded 1-2 and 2-4 times, respectively, that of B[a]P at the four sampling sites; therefore underestimation of the cancer risk posed by PAHs in air could be made if the DBPs were not considered in risk assessment using the toxic equivalency approach, whilst the high correlation (p big difference in concentration ratios of B[a]P and the DBPs between the present study and some literature data calls for further research to evaluate the temporal and spatial invariance of the B[a]P/DBP ratios.

  4. Martian Meteorology: Determination of Large Scale Weather Patterns from Surface Measurements

    Science.gov (United States)

    Murphy, James R.; Haberle, Robert M.; Bridger, Alison F. C.

    1998-01-01

    We employed numerical modelling of the martian atmosphere, and our expertise in understanding martian atmospheric processes, to better understand the coupling between lower and upper atmosphere processes. One practical application of this work has been our involvement with the ongoing atmospheric aerobraking which the Mars Global Surveyor (MGS) spacecraft is currently undergoing at Mars. Dr. Murphy is currently a member of the Mars Global Surveyor (MGS) Aerobraking Atmospheric Advisory Group (AAG). He was asked to participate in this activity based upon his knowledge of martian atmospheric dynamical processes. Aerobraking is a process whereby a spacecraft, in an elliptical orbit, passes through the upper layers of the atmosphere (in this instance Mars). This passage through the atmosphere 'drags'upon the spacecraft, gradually reducing its orbital velocity. This has the effect, over time, of converting the elliptical orbit to a circular orbit, which is the desired mapping orbit for MGS. Carrying out aerobraking eliminates the need for carrying large amounts of fuel on the spacecraft to execute an engine burn to achieve the desired orbit. Eliminating the mass of the fuel reduces the cost of launch. Damage to one of MGS's solar panels shortly after launch has resulted in a less aggressive extended in time aerobraking phase which will not end until March, 1999. Phase I extended from Sept. 1997 through March 1998. During this time period, Dr. Murphy participated almost daily in the AAG meetings, and beginning in December 1997 lead the meeting several times per week. The leader of each of the daily AAG meetings took the results of that meeting (current state of the atmosphere, identification of any time trends or spatial patterns in upper atmosphere densities, etc.) forward to the Aerobraking Planning Group (APG) meeting, at which time the decision was made to not change MGS orbit, to lower the orbit to reach higher densities (greater 'drag'), or raise the orbit to avoid

  5. Large residuals on geoidal heights determined on the Fagnano Lake, Tierra del Fuego-Argentina

    Science.gov (United States)

    Gomez, M. E.; Del Cogliano, D.; Perdomo, R.

    2013-05-01

    A new geoid model was developed in Tierra del Fuego and it was evaluated in the area of Fagnano Lake. The model was developed by means of the Equivalent Source Technique combining gravity data, levelling information measured on the province and observations of a GPS buoy on the Fagnano Lake. Those GPS buoy measurements provide information of the mean lake level surface (Del Cogliano et al., 2007). A cross validation process was realized in order to evaluate the model on the lake. What allowed determining a 6 cm geoid in the area of Fagnano Lake. Also, an evaluation of the EGM2008 (Pavlis et al., 2008) was made on the lake. Its behaviour was compared to that observed on the levelling lines. Differences of several decimetres were found when EGM2008 undulations were compared to observed geoid undulations in the lake area. In the regions where EGM2008 has included real gravimetric observations, differences between model and observations were only of a few centimetres. Such model has the particularity that includes fill-in gravity in that region. The above mentioned evaluation derived in an analysis of the effect that not representative gravity information could have on the estimation of geoid undulations in high mountainous regions. We found that this effect could be significant if there is no real information in the computing area (Gomez et al, 2012).

  6. Dynamic Volatility Arbitrage

    DEFF Research Database (Denmark)

    Dorn, Jochen

    concepts, next to nothing is known about position reverting strategies and how, and -even more important- in which context they are applied in practice. In the recent market downturn only one sector generated signicant profits for the leading investment banks: Volatility trading activities, namely on Forex...

  7. Determination of acrolein, ethanol, volatile acidity, and copper in different samples of sugarcane spirits Determinação de acroleína, etanol, acidez volátil e cobre em diferentes amostras de aguardentes de cana

    Directory of Open Access Journals (Sweden)

    José Masson

    2012-09-01

    Full Text Available Seventy-one samples of sugarcane spirits from small and average size stills produced in the northern and southern Minas Gerais (Brazil were analyzed for acrolein using HPLC (High Performance Liquid Chromatography. Ethanol and copper concentrations and volatile acidity were also determined according to methods established by the Ministry of Agriculture, Livestock and Supply (MAPA. A total of 9.85% of the samples tested showed levels of acrolein above the legal limits, while the copper concentrations of 21.00% of the samples and the volatile acidity of 8.85% of the samples were higher than the limits established by the Brazilian legislation. The concentration of acrolein varied from 0 to 21.97 mg.100 mL-1 of ethanol. However, no significant difference at 5% of significance was observed between the samples produced in the northern and southern Minas Gerais. The method used for determination of acrolein in sugarcane spirits involved the formation of a derivative with 2,4-dinitrophenylhydrazine (2,4-DNPH and subsequent analysis by HPLC.As setenta e uma amostras de aguardentes de cana coletadas em alambiques de pequeno e médio porte, provenientes das regiões norte e sul de Minas Gerais, foram avaliadas por CLAE (Cromatografia Líquida de Alta Eficiência quanto ao teor de acroleína. Avaliaram-se também as concentrações de etanol, acidez volátil e cobre, utilizando-se as metodologias estabelecidas pelo Ministério da Agricultura, Pecuária e Abastecimento (MAPA. Do total de amostras, 9,85% apresentaram níveis de acroleína acima do limite legal, 21,00% apresentaram teores de cobre e 8,85% de acidez volátil acima dos limites estabelecidos pela legislação brasileira. Os teores de acroleína variaram de 0 a 21,97 mg.100 mL-1 de etanol. Entretanto, não ocorreu diferença significativa no nível de 5% de significância entre as amostras do norte e as do sul de Minas Gerais. O método aplicado para a determinação de acroleína em aguardente de

  8. Volatile organic compounds determination in the atmosphere of Mexico City by the use of optical systems and non conventional methods; Determinacion de compuestos organicos volatiles en la atmosfera de la Ciudad de Mexico mediante el uso de sistemas opticos y metodos convencionales

    Energy Technology Data Exchange (ETDEWEB)

    Ruiz, Maria Esther; Arriaga, Jose Luis; Garcia, Isidoro [Gerencia de Ciencias de Ambiente, Instituto Mexicano del Petroleo, Mexico, D.F. (Mexico)

    1996-04-01

    Since 1991, volatile organic compounds (VOC) have been determined in Mexico City Metropolitan Area (MCMA) using different analyzing methods. Samples collected in cartridges and canisters area analyzed by GC-MS and HPLC. Continuos monitoring by a long path differential absorption analyzer (DOAS) has also been performed. The Mexican Petroleum Institute (IMP) along with the USEPA and the collaboration of the Mexican environmental authorities have performed, following the EPA TO-14 method, four sampling campaigns of ambient air in canisters among 1992 and 1993. The campaigns were designed to be performed during March, month in which the worst ozone episodes have taken place. Additional sampling was performed in November in order to compare differences between seasons. In March 1993, samples in three different kinds of cartridges were used which selectively adsorb carbonyl compounds, light hydrocarbons (C{sub 2}-C{sub 4}) and heavier hydrocarbons (C{sub 5}-C{sub 1}5). The three techniques employed, canisters, cartridges and the DOAS, reveal very high atmospheric concentrations of the volatile organic compounds, species identified as ozone precursors, these high concentration might appear as responsible for the ozone standards excess. The kinetics of the whole set of atmospheric reactions points then to nitrogen oxides as the limiting species since their relative smaller abundance. This fact engender a NOx limited atmosphere. The three techniques offer different advantages for the determination of species in the atmosphere, the canisters samples provides the total VOC concentration, the speciation of more than 200 compounds and the determination of CO and CH{sub 4}. The sampling in cartridges could be used to detect occasional emissions. On the other hand the DOAS provides the means to follow the evolution of selected species during long periods and the influence of meteorological parameters as the wind speed and direction, on the concentration of each pollutant. The

  9. The Impact of Jump Distributions on the Implied Volatility of Variance

    DEFF Research Database (Denmark)

    Nicolato, Elisa; Pedersen, David Sloth; Pisani, Camilla

    2016-01-01

    of jumps on the associated implied volatility smile. We provide sufficient conditions for the asymptotic behavior of the implied volatility of variance for small and large strikes. In particular, by selecting alternative jump distributions, we show that one can obtain fundamentally different shapes...... of the implied volatility of variance smile -- some clearly at odds with the upward-sloping volatility skew observed in variance markets....

  10. The Impact of Jump Distributions on the Implied Volatility of Variance

    DEFF Research Database (Denmark)

    Nicolato, Elisa; Pisani, Camilla; Pedersen, David Sloth

    2017-01-01

    of jumps on the associated implied volatility smile. We provide sufficient conditions for the asymptotic behavior of the implied volatility of variance for small and large strikes. In particular, by selecting alternative jump distributions, we show that one can obtain fundamentally different shapes...... of the implied volatility of variance smile -- some clearly at odds with the upward-sloping volatility skew observed in variance markets....

  11. Auto-correlated behavior of WTI crude oil volatilities: A multiscale perspective

    Science.gov (United States)

    Wang, Yudong; Wei, Yu; Wu, Chongfeng

    2010-12-01

    In this paper, we investigate the long-range auto-correlated behavior of WTI crude oil volatility series employing multifractal detrended fluctuation analysis. Our findings show that the for small time scales, the auto-correlations of volatilities were multifractal while for large time scales, the auto-correlations were nearly monofractal. Based on multiscale analysis, we also investigate the dynamics of auto-correlations for different intervals of time scales and find that several shocks could make significant effects on the auto-correlated behaviors for small time scales. Analyzing the dynamics of multifractality degrees of auto-correlations for small time scales, we find that the stronger auto-correlations were always related to the lower degrees of multifractality. At last, we have discussions on the determination factors of price behavior, the predictive implications of scaling behavior in volatilities for oil markets and the reasons why long-range auto-correlations of volatility were always strong for both small time scales and large time scales. Our results are very important theoretically and practically.

  12. Large eddy simulations of forest canopies for determination of biological dispersal by wind

    Science.gov (United States)

    Bohrer, Gil

    Forest canopies interact with the atmosphere by emitting heat and moisture fluxes, by dragging the flow and by forming obstacles to the flow. Forests are heterogeneous with structural features at a vast range of length scale. The atmospheric effects of micro-scale canopy structures, which describe differences between individual trees, have so far been poorly studied. Changes to turbulence, flow patterns, and fluxes in and above the canopy strongly affect the dispersal of seeds and its ecological consequences because they are strongly dependent on the far "tail" of the dispersal distribution. The Regional Atmospheric Modeling System (RAMS) is further developed to operate as a large-eddy simulation (LES) at high resolution with 3D heterogeneous forest canopies. This RAMS-based Forest LES (RAFLES) represents the canopy through drag, volume restriction by stems, and heat and moisture fluxes in the canopy domain. The model incorporates explicit canopy descriptions, which can be obtained from observations, or from the virtual-canopy generator, which is developed here. RAFLES is used to simulate noontime conditions for two days at the hardwood stand in the Duke Forest, representing two sets of atmospheric and canopy conditions. The results are evaluated against eddy-flux observations from these days. RAFLES compares well to the observed data. Comparison between artificial homogeneous cases and natural heterogeneous cases reveals that small-scale canopy heterogeneity affects the profiles of momentum and scalar fluxes, and modifies the spatial structure of the flow. Low areas in the canopy promote ejection events, which leads to a correlation between the canopy height and flow variables that extends up to four times the canopy height. Seed dispersal kernels simulated with RAFLES closely match those measured in seed release experiments in a temperate forest. It is also used to examine potential biases resulting from simplifications in common dispersal models, such as planar

  13. Volatile compound formation during argan kernel roasting.

    Science.gov (United States)

    El Monfalouti, Hanae; Charrouf, Zoubida; Giordano, Manuela; Guillaume, Dominique; Kartah, Badreddine; Harhar, Hicham; Gharby, Saïd; Denhez, Clément; Zeppa, Giuseppe

    2013-01-01

    Virgin edible argan oil is prepared by cold-pressing argan kernels previously roasted at 110 degrees C for up to 25 minutes. The concentration of 40 volatile compounds in virgin edible argan oil was determined as a function of argan kernel roasting time. Most of the volatile compounds begin to be formed after 15 to 25 minutes of roasting. This suggests that a strictly controlled roasting time should allow the modulation of argan oil taste and thus satisfy different types of consumers. This could be of major importance considering the present booming use of edible argan oil.

  14. Chemical diversity of volatiles of Teucrium orientale L. var. orientale, var. puberulens, and var. glabrescens determined by simultaneous GC-FID and GC/MS techniques.

    Science.gov (United States)

    Ozek, Gulmira; Ozek, Temel; Dinç, Muhittin; Doǧu, Süleyman; Başer, Kemal H C

    2012-06-01

    In the present work, three varieties of Teucrium orientale, var. orientale, var. puberulens, and var. glabrescens, were collected and investigated for chemical composition of the oils. Subsequent gas chromatography (GC-FID) and gas chromatography coupled to mass spectrometry (GC/MS) revealed high abundance of sesquiterpenes in the essential oils analyzed. All the oils contained β-caryophyllene (22.6, 8.5, and 6.3%, resp.) and hexadecanoic acid (7.9, 12.8, and 13.1%). Germacrene D (24.6 and 33.4%) and bicyclogermacrene (6.7 and 8.5%) were found to be the main constituents of var. orientale and var. puberulens, respectively. The high percentages of β-cubebene (26.9%), α-cubebene (9.0%), and α-copaene (7.2%) established the diversity of var. glabrescens. The qualitative difference between the essential oils allowed the differentiation between the varieties in agreement with the morphological observations described in Flora of Turkey for each variety studied. In addition, a cluster analysis of twelve Teucrium taxa based on the essential-oil composition has been carried out. Hovewer, the analysis did not clearly reflect the infrageneric classification of the genus, it largely confirmed the relationships between the infraspecific taxa of Teucrium orientale and T. chamaedrys.

  15. The exploitation of volatile oil

    Institute of Scientific and Technical Information of China (English)

    MENG Teng; ZHANG Da; TENG Xiangjin; LINing; HAO Zaibin

    2007-01-01

    Rose is a kind of favorite ornamental plant. This article briefly introduced the cultivation and the use of rose around the world both in ancient time and nowadays. Today, volatile oil becomes the mainstream of the rose industry. People pay attention to the effect of volatile oil; meanwhile, they speed up their research on extracting volatile oil and the ingredients.

  16. Plant volatiles and the environment

    NARCIS (Netherlands)

    Loreto, F.; Dicke, M.; Schnitzler, J.P.; Turlings, T.C.J.

    2014-01-01

    Volatile organic compounds emitted by plants represent the largest part of biogenic volatile organic compounds (BVOCs) released into our atmosphere. Plant volatiles are formed through many biochemical pathways, constitutively and after stress induction. In recent years, our understanding of the func

  17. Determination of volatile components in fresh, frozen, and freeze-dried Padrón-type peppers by gas chromatography-mass spectrometry using dynamic headspace sampling and microwave desorption.

    Science.gov (United States)

    Oruña-Concha, M J; López-Hernández, J; Simal-Lozano, J A; Simal-Gándara, J; González-Castro, M J; de la Cruz García, C

    1998-12-01

    "Padrón-type" peppers are a small variety of Capsicum annuum cultivated mainly in Galicia, Spain. To compare the effects of freezing and freeze-drying on the volatile components of Padrón-type peppers, preserved samples are analyzed by means of dynamic headspace sampling on an adsorbent followed by microwave desorption into a gas chromatograph equipped with a mass spectrometric detector. Sixty-five compounds are identified, including hydrocarbons, terpenes, alcohols, phenols, ethers, aldehydes, ketones, esters, pyrroles, pyrazines, and sulfurous compounds. Fresh whole, homogenized, and freeze-dried peppers have characteristic volatile-component profiles, whereas frozen peppers have a highly variable volatile-component profile.

  18. Fate of Volatile Organic Compounds in Constructed Wastewater Treatment Wetlands

    Science.gov (United States)

    Keefe, S.H.; Barber, L.B.; Runkel, R.L.; Ryan, J.N.

    2004-01-01

    The fate of volatile organic compounds was evaluated in a wastewater-dependent constructed wetland near Phoenix, AZ, using field measurements and solute transport modeling. Numerically based volatilization rates were determined using inverse modeling techniques and hydraulic parameters established by sodium bromide tracer experiments. Theoretical volatilization rates were calculated from the two-film method incorporating physicochemical properties and environmental conditions. Additional analyses were conducted using graphically determined volatilization rates based on field measurements. Transport (with first-order removal) simulations were performed using a range of volatilization rates and were evaluated with respect to field concentrations. The inverse and two-film reactive transport simulations demonstrated excellent agreement with measured concentrations for 1,4-dichlorobenzene, tetrachloroethene, dichloromethane, and trichloromethane and fair agreement for dibromochloromethane, bromo-dichloromethane, and toluene. Wetland removal efficiencies from inlet to outlet ranged from 63% to 87% for target compounds.

  19. Development and validation of a direct headspace GC-FID method for the determination of sevoflurane, desflurane and other volatile compounds of forensic interest in biological fluids: application on clinical and post-mortem samples.

    Science.gov (United States)

    Kovatsi, Leda; Giannakis, Dimitrios; Arzoglou, Vasileios; Samanidou, Victoria

    2011-05-01

    A simple and reliable headspace GC-flame ionization detection (HS-GC-FID) method has been developed and validated for the simultaneous determination of seven volatile compounds of forensic interest: sevoflurane, desflurane, ethanol, methanol, 1-propanol, acetone and acetaldehyde. All seven compounds including acetonitrile (internal standard) eluted within 10 min and were well resolved with no endogenous interference. Good linearity was observed in the range of 1-12 mg/dL for both anesthetics and 2.5-40 mg/dL for the other five analytes. The method showed good precision, sensitivity and repeatability. Most of the analytes remained stable during the storage of samples at 4°C. Desflurane and acetone degraded (>10%), when the samples remained on the autosampler for more than 2 and 3 h, respectively. The method was finally applied on clinical and post-mortem blood and urine samples. The clinical samples were collected both from patients who underwent surgery, as well as from the occupationally exposed medical and nursing staff of the university hospital, working in the operating rooms. The hospital staff samples were found negative for all compounds, while the patients' samples were found positive for the anesthetic administered to the patient. The post-mortem blood samples were found positive for ethanol and acetaldehyde.

  20. Determination of volatile aroma compounds in litchi vinegar by HS-SPME-GC/MS%顶空固相微萃取-气质联用测定荔枝果醋中挥发性成分

    Institute of Scientific and Technical Information of China (English)

    李巍青; 王浩; 蒋丽婷; 李理

    2011-01-01

    采用顶空固相微萃取结合气质联用法测定了荔枝果醋中的挥发性成分,共检测出34种物质,包括酸类、醇类、醛酮类、酯类、烃类化合物以及少量其它化合物.采用面积归一法进行分析可知:主要成分为醋酸(61.6%)、乙酸乙酯(7.91%)、3-羟基-2-丁酮(6.44%)、乙酸异戊酯(2.97%)、乙酸苯乙酯(2.87%)、邻苯二甲酸二异丁酯(2.25%)、(2R,3R)-(-)-2,3-丁二醇(2.09%)、醋酸异丁酯(1.74%)、2,3-丁二醇(1.61%)、辛酸乙酯(1.42%)、乙酸-2-甲基丁酯(1.37%)、乙醇(1.25%).%The volatile compounds of Litchi vinegar were extracted by solid phase micro extraction and were identified by the analysis of gas chro-matography-mass spectrometry. About 34 different components were identified including acids, alcohols, aldehydes, ketones, esters, hydrocarbons and a few other compounds. The percentage of each component was determined by area normalization. It was indicated that the main volatile components in the Litchi vinegar were acetic acid (61.6%), ethyl acetate (7.91%), 3-hydroxy-2-butanone (6.44%), isoamyl acetate (2.97%), phenethyl acetate (2.87%), diisobutyl phthalate (2.25%), (2R,3R)-(-)-2,3-butanediol (2.09%), isobutyl acetate (1.74%), 2,3-butanediol (1.61%), octanoic acid ethyl ester (1.42%), acetic acid 2-methylbutyl ester (1.37%), ethyl alcohol (1.25%).

  1. Evaluation of {gamma}-radiation on green tea odor volatiles

    Energy Technology Data Exchange (ETDEWEB)

    Fanaro, G.B., E-mail: gbfanaro@ipen.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN)-Centro de Tecnologia das Radiacoes, Av. Professor Lineu Prestes, 2242, 05508-000 Sao Paulo, SP (Brazil); Duarte, R.C., E-mail: renatocduarte@yahoo.com.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN)-Centro de Tecnologia das Radiacoes, Av. Professor Lineu Prestes, 2242, 05508-000 Sao Paulo, SP (Brazil); Araujo, M.M., E-mail: mmozeika@yahoo.co [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN)-Centro de Tecnologia das Radiacoes, Av. Professor Lineu Prestes, 2242, 05508-000 Sao Paulo, SP (Brazil); Purgatto, E., E-mail: epurgatt@usp.b [Universidade de Sao Paulo-Faculdade de Ciencias Farmaceuticas, FCF/USP, Departamento de Alimentos e Nutricao Experimental, Av. Prof. Lineu Prestes, 580 Bloco 14, 05508-900, Sao Paulo, SP (Brazil); Villavicencio, A.L.C.H., E-mail: villavic@ipen.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN)-Centro de Tecnologia das Radiacoes, Av. Professor Lineu Prestes, 2242, 05508-000 Sao Paulo, SP (Brazil)

    2011-01-15

    The aim of this study was to evaluate the gamma radiation effects on green tea odor volatiles in green tea at doses of 0, 5, 10, 15 and 20 kGy. The volatile organic compounds were extracted by hydrodistillation and analyzed by GC/MS. The green tea had a large influence on radiation effects, increasing the identified volatiles in relation to control samples. The dose of 10 kGy was responsible to form the majority of new odor compounds following by 5 and 20 kGy. However, the dose of 5 kGy was the dose that degraded the majority of volatiles in non-irradiated samples, following by 20 kGy. The dose of 15 kGy showed has no effect on odor volatiles. The gamma radiation, at dose up to 20 kGy, showed statistically no difference between irradiated and non irradiated green tea on odors compounds.

  2. Evaluation of γ-radiation on green tea odor volatiles

    Science.gov (United States)

    Fanaro, G. B.; Duarte, R. C.; Araújo, M. M.; Purgatto, E.; Villavicencio, A. L. C. H.

    2011-01-01

    The aim of this study was to evaluate the gamma radiation effects on green tea odor volatiles in green tea at doses of 0, 5, 10, 15 and 20 kGy. The volatile organic compounds were extracted by hydrodistillation and analyzed by GC/MS. The green tea had a large influence on radiation effects, increasing the identified volatiles in relation to control samples. The dose of 10 kGy was responsible to form the majority of new odor compounds following by 5 and 20 kGy. However, the dose of 5 kGy was the dose that degraded the majority of volatiles in non-irradiated samples, following by 20 kGy. The dose of 15 kGy showed has no effect on odor volatiles. The gamma radiation, at dose up to 20 kGy, showed statistically no difference between irradiated and non irradiated green tea on odors compounds.

  3. Volatilization behaviors of diesel oil from the soils

    Institute of Scientific and Technical Information of China (English)

    LI Yu-ying; ZHENG Xi-lai; LI Bing; MA Yu-xin; CAO Jing-hua

    2004-01-01

    The volatilization of diesel oil, Shengli crude oil and 90# gasoline on glass surface of petri dishes were conducted at the ambient temperature of 25℃. Diesel oil evaporates in a power manner, where the loss of mass is approximately power with time. 90# gasoline evaporates in a logarithmic with time. Where as the volatilization of Shengli crude oil fit either the logarithmic or power equation after different time, and has similar R2. And the effects of soil type and diesel oil and water content on volatilization behavior in unsaturated soil were studied in this paper. Diesel oil and water content in the soils play a large role in volatilization from soils. Appropriate water helps the wicking action but too much water stops it. The wicking action behaves differently in four different types of soils in the same volatilization experiment of 18% diesel oil content and air-dry condition.

  4. Hill-type muscle model parameters determined from experiments on single muscles show large animal-to-animal variation.

    Science.gov (United States)

    Blümel, Marcus; Guschlbauer, Christoph; Daun-Gruhn, Silvia; Hooper, Scott L; Büschges, Ansgar

    2012-11-01

    Models built using mean data can represent only a very small percentage, or none, of the population being modeled, and produce different activity than any member of it. Overcoming this "averaging" pitfall requires measuring, in single individuals in single experiments, all of the system's defining characteristics. We have developed protocols that allow all the parameters in the curves used in typical Hill-type models (passive and active force-length, series elasticity, force-activation, force-velocity) to be determined from experiments on individual stick insect muscles (Blümel et al. 2012a). A requirement for means to not well represent the population is that the population shows large variation in its defining characteristics. We therefore used these protocols to measure extensor muscle defining parameters in multiple animals. Across-animal variability in these parameters can be very large, ranging from 1.3- to 17-fold. This large variation is consistent with earlier data in which extensor muscle responses to identical motor neuron driving showed large animal-to-animal variability (Hooper et al. 2006), and suggests accurate modeling of extensor muscles requires modeling individual-by-individual. These complete characterizations of individual muscles also allowed us to test for parameter correlations. Two parameter pairs significantly co-varied, suggesting that a simpler model could as well reproduce muscle response.

  5. Clustered volatility in multiagent dynamics

    CERN Document Server

    Youssefmir, M; Youssefmir, Michael; Huberman, Bernardo

    1995-01-01

    Large distributed multiagent systems are characterized by vast numbers of agents trying to gain access to limited resources in an unpredictable environment. Agents in these system continuously switch strategies in order to opportunistically find improvements in their utilities. We have analyzed the fluctuations around equilibrium that arise from strategy switching and discovered the existence of a new phenomenon. It consists of the appearance of sudden bursts of activity that punctuate the fixed point, and is due to an effective random walk consistent with overall stability. This clustered volatility is followed by relaxation to the fixed point but with different strategy mixes from the previous one. This phenomenon is quite general for systems in which agents explore strategies in search of local improvements.

  6. Scaling Foreign Exchange Volatility

    OpenAIRE

    Jonathan Batten; Craig Ellis

    2001-01-01

    When asset returns are normally distributed the risk of an asset over a long return interval may be estimated by scaling the risk from shorter return intervals. While it is well known that asset returns are not normally distributed a key empirical question concerns the effect that scaling the volatility of dependent processes will have on the pricing of related financial assets. This study provides an insight into this issue by investigating the return properties of the most important currenc...

  7. Experimental determination of quantum-well lifetime effect on large-signal resonant tunneling diode switching time

    Energy Technology Data Exchange (ETDEWEB)

    Growden, Tyler A.; Berger, Paul R., E-mail: pberger@ieee.org [Department of Electrical and Computer Engineering, The Ohio State University, Columbus, Ohio 43210 (United States); Brown, E. R.; Zhang, Weidong [Departments of Physics and Electrical Engineering, Wright State University, Dayton, Ohio 45435 (United States); Droopad, Ravi [Ingram School of Engineering, Texas State University, San Marcos, Texas 78666 (United States)

    2015-10-12

    An experimental determination is presented of the effect the quantum-well lifetime has on a large-signal resonant tunneling diode (RTD) switching time. Traditional vertical In{sub 0.53}Ga{sub 0.47}As/AlAs RTDs were grown, fabricated, and characterized. The switching time was measured with a high-speed oscilloscope and found to be close to the sum of the calculated RC-limited 10%–90% switching time and the quantum-well quasibound-state lifetime. This method displays experimental evidence that the two intrinsic resonant-tunneling characteristic times act independently, and that the quasibound-state lifetime then serves as a quantum-limit on the large-signal speed of RTDs.

  8. Ion Exclusion Chromatography Method Determination of Volatile Organic Acids and Lactic Acid in the Environmental Samples%离子排斥色谱法测定环境样品中挥发性有机酸及乳酸

    Institute of Scientific and Technical Information of China (English)

    杨学灵; 林瑛

    2011-01-01

    Volatile organic acids and lactic acid in the environmental samples were simultaneously determined by ion exclusion chromatography(IEC) method.The concentration and velocity of mobile phase were examined for the effects to the separation of organic acids.The results showed that lactic acid,formic acid,acetic acid,propionic acid,butyric acid and pentanoic acid were completely separated.The measured concentrations of organic acids showed good linear relationships with those peak heights in a certain range.The detection limits were less than 0.10 mg/L.The concentrations of organic acids in molasses alcohol waste and digested sludge were determined and the results met the testing requirements.The relative standard derivations were from 2.2% to 5.6%.%提出了同时测定环境样品中挥发性有机酸及乳酸的离子排斥色谱法(IEC法)。考察了流动相浓度、流速对有机酸分离的影响。实验结果表明,乳酸、甲酸、乙酸、丙酸、正丁酸和正戊酸可达到完全分离,被测组分的浓度与其峰高在一定的范围呈良好的线性关系,检出限均低于0.10 mg/L。测定了糖蜜酒精废水和消化污泥中有机酸的含量,结果满足检测的要求,样品中各组分的相对标准偏差为2.2%~5.6%。

  9. 同时测定水中10种卤代有机挥发物的顶空气相色谱法%Simultaneous determination of 10 kinds of halogenated organic volatiles with headspace gas chromatography in water

    Institute of Scientific and Technical Information of China (English)

    尹华; 陈平; 陈振为

    2012-01-01

    [Objective]To establish a method for simultaneous determination of 10 kinds of volatile halogenated compounds with headspace-gas chromatography (HS-GC ) in water. [Methods]After separation of in water by CP-Sil 5CB capillarity column, 10 kinds of organic compounds were detected quantitatively by electron capture detector (ECD). [Results]The correlation coefficient of 10 kinds of organic compounds was 0. 999 1-0. 999 9, the average recovery was 89. 3%-105% (re = 6) , the RSD was 1.5%-5.5% , and the minimum detectable concentration was 0.30-20.16 μg/L. [Conclusion]The method is simple, rapid, accurate and sensitive, and it is suitable for the determination of halogenated organic compounds in water.%目的 建立同时测定生活饮用水中10种挥发性卤代化合物的顶空-气相色谱方法.方法 水中10种有机物经CP-Sil 5CB毛细管色谱柱分离,电子捕获检测器(ECD)检测,外标法定量.结果 10种有机物的线性相关系数为0.999 1 ~0.999 9,平均加样回收率为89.3% ~ 105% (n =6),RSD为1.5% ~5.5%,最低检出浓度为0.30 ~20.16.μg/L.结论 该方法操作简单,快速,准确,灵敏度较高,适用于水中卤代有机物的测定.

  10. Measuring the atmospheric organic aerosol volatility distribution: a theoretical analysis

    Directory of Open Access Journals (Sweden)

    E. Karnezi

    2014-01-01

    Full Text Available Organic compounds represent a significant fraction of submicrometer atmospheric aerosol mass. Even if most of these compounds are semi-volatile in atmospheric concentrations, the ambient organic aerosol volatility is quite uncertain. The most common volatility measurement method relies on the use of a thermodenuder (TD. The aerosol passes through a heated tube where its more volatile components evaporate leaving the less volatile behind in the particulate phase. The typical result of a~thermodenuder measurement is the mass fraction remaining (MFR, which depends among other factors on the organic aerosol (OA vaporization enthalpy and the accommodation coefficient. We use a new method combining forward modeling, introduction of "experimental" error and inverse modeling with error minimization for the interpretation of TD measurements. The OA volatility distribution, its effective vaporization enthalpy, the mass accommodation coefficient and the corresponding uncertainty ranges are calculated. Our results indicate that existing TD-based approaches quite often cannot estimate reliably the OA volatility distribution, leading to large uncertainties, since there are many different combinations of the three properties that can lead to similar thermograms. We propose an improved experimental approach combining TD and isothermal dilution measurements. We evaluate this experimental approach using the same model and show that it is suitable for studies of OA volatility in the lab and the field.

  11. Determining the physical processes behind four large eruptions in rapid sequence in the San Juan caldera cluster (Colorado, USA)

    Science.gov (United States)

    Curry, Adam; Caricchi, Luca; Lipman, Peter

    2017-04-01

    Large, explosive volcanic eruptions can have both immediate and long-term negative effects on human societies. Statistical analyses of volcanic eruptions show that the frequency of the largest eruptions on Earth (> ˜450 km3) differs from that observed for smaller eruptions, suggesting different physical processes leading to eruption. This project will characterize the petrography, whole-rock geochemistry, mineral chemistry, and zircon geochronology of four caldera-forming ignimbrites from the San Juan caldera cluster, Colorado, to determine the physical processes leading to eruption. We collected outflow samples along stratigraphy of the three caldera-forming ignimbrites of the San Luis caldera complex: the Nelson Mountain Tuff (>500 km3), Cebolla Creek Tuff (˜250 km3), and Rat Creek Tuff (˜150 km3); and we collected samples of both outflow and intracaldera facies of the Snowshoe Mountain Tuff (>500 km3), which formed the Creede caldera. Single-crystal sanidine 40Ar/39Ar ages show that these eruptions occurred in rapid succession between 26.91 ± 0.02 Ma (Rat Creek) and 26.87 ± 0.02 Ma (Snowshoe Mountain), providing a unique opportunity to investigate the physical processes leading to a rapid sequence of large, explosive volcanic eruptions. Recent studies show that the average flux of magma is an important parameter in determining the frequency and magnitude of volcanic eruptions. High-precision isotope-dilution thermal ionization mass spectrometry (ID-TIMS) zircon geochronology will be performed to determine magma fluxes, and cross-correlation of chemical profiles in minerals will be performed to determine the periodicity of magma recharge that preceded these eruptions. Our project intends to combine these findings with similar data from other volcanic regions around the world to identify physical processes controlling the regional and global frequency-magnitude relationships of volcanic eruptions.

  12. Flow Curve Determination at Large Plastic Strain Levels to Accurately Constitutive Equations of AHSS in Forming Simulation

    Science.gov (United States)

    Lemoine, X.; Sriram, S.; Kergen, R.

    2011-05-01

    ArcelorMittal continuously develops new steel grades (AHSS) with high performance for the automotive industry to improve the weight reduction and the passive safety. The wide market introduction of AHSS raises a new challenge for manufacturers in terms of material models in the prediction of forming—especially formability and springback. The relatively low uniform elongation, the high UTS and the low forming limit curve of these AHSS may cause difficulties in forming simulations. One of these difficulties is the consequence of the relatively low uniform elongation on the parameters identification of isotropic hardening model. Different experimental tests allow to reach large plastic strain levels (hydraulic bulge test, stack compression test, shear test…). After a description on how to determine the flow curve in these experimental tests, a comparison of the different flow curves is made for different steel grades. The ArcelorMittal identification protocol for hardening models is only based on stress-strain curves determined in uniaxial tension. Experimental tests where large plastic strain levels are reached are used to validate our identification protocol and to recommend some hardening models. Finally, the influence of isotropic hardening models and yield loci in forming prediction for AHSS steels will be presented.

  13. Determination of α-pinene, Eucalyptol and Borneol in Volatile Oil from Zingiber officinale Roscoe by GC-MS%GC-MS测定姜油中α-蒎烯·桉油精和龙脑的含量

    Institute of Scientific and Technical Information of China (English)

    马雯芳; 谭建宁; 徐东来; 严克剑

    2012-01-01

    [目的]建立GC-MS同时测定姜油中α-蒎烯、桉油精、龙脑含量的方法.[方法]以GC-MS测定姜油中α-蒎烯、桉油精、龙脑的含量.[结果]α-蒎烯、桉油精、龙脑的浓度分别在20.01 ~300.15 μg/ml(r=0.9995)、34.74~521.10 μg/ml(r =0.999 0)、6.48 ~97.20μg/ml(r =0.999 5)范围成良好线性关系;平均加样回收率(n=6)分别为101.09(RSD 1.35%)、97.78%(RSD 1.86%)、103.28%(RSD1.57%).[结论]该方法灵敏、快速、准确,可为姜油的质量控制提供依据.%[ Objective] To establish a method for determination of a-pinene, euealyptol and boireol in volatiJe oil from Zingiber officinnle Roscoe by GC-MS. [ Method] Contents of a-pinene, eucalyptoi and faomeol in volatile oil from Zingiber officinale Roacoe were determined by GC-MS. [Result] The luiearity of o-pinene, eucalyptol and bomeol were shown in the range of 20.01 -300.15 礸/ml (r = 0.999 5), 34. 74 -521.10 礸/ml (r = 0.999 0) and6.48 -97.20 礸/ml (r =0.999 5). The average recovery rate of a-pinene, eucalyptol and bomeol were 101. 09% with RSD of 1. 35% , 97.78% with RSD of 1. 86% , and 103. 28% with RSD of 1.57 % (n = 6) respectively. [ Conclusion ] The determination method is sensitive, rapid and accurate, it could be user! as the determination method for Zingiber offwirwle Roscoe.

  14. Diel variation in fig volatiles across syconium development: making sense of scents.

    Science.gov (United States)

    Borges, Renee M; Bessière, Jean-Marie; Ranganathan, Yuvaraj

    2013-05-01

    Plants produce volatile organic compounds (VOCs) in a variety of contexts that include response to abiotic and biotic stresses, attraction of pollinators and parasitoids, and repulsion of herbivores. Some of these VOCs may also exhibit diel variation in emission. In Ficus racemosa, we examined variation in VOCs released by fig syconia throughout syconium development and between day and night. Syconia are globular enclosed inflorescences that serve as developing nurseries for pollinating and parasitic fig wasps. Syconia are attacked by gallers early in their development, serviced by pollinators in mid phase, and are attractive to parasitoids in response to the development of gallers at later stages. VOC bouquets of the different development phases of the syconium were distinctive, as were their day and night VOC profiles. VOCs such as α-muurolene were characteristic of the pollen-receptive diurnal phase, and may serve to attract the diurnally-active pollinating wasps. Diel patterns of release of volatiles could not be correlated with their predicted volatility as determined by Henry's law constants at ambient temperatures. Therefore, factors other than Henry's law constant such as stomatal conductance or VOC synthesis must explain diel variation in VOC emission. A novel use of weighted gene co-expression network analysis (WGCNA) on the volatilome resulted in seven distinct modules of co-emitted VOCs that could be interpreted on the basis of syconium ecology. Some modules were characterized by the response of fig syconia to early galling by parasitic wasps and consisted largely of green leaf volatiles (GLVs). Other modules, that could be characterized by a combination of syconia response to oviposition and tissue feeding by larvae of herbivorous galler pollinators as well as of parasitized wasps, consisted largely of putative herbivore-induced plant volatiles (HIPVs). We demonstrated the usefulness of WGCNA analysis of the volatilome in making sense of the scents

  15. Behavioural determinants of gene flow in malaria vector populations: Anopheles gambiae males select large females as mates

    Directory of Open Access Journals (Sweden)

    Yan G

    2002-08-01

    Full Text Available Abstract Background Plasmodium-refractory mosquitoes are being rapidly developed for malaria control but will only succeed if they can successfully compete for mates when released into the wild. Pre-copulatory behavioural traits maintain genetic population structure in wild mosquito populations and mating barriers have foiled previous attempts to control malaria vectors through sterile male release. Methods Varying numbers of virgin male and female Anopheles gambiae Giles, from two strains of different innate sizes, were allowed to mate under standardized conditions in laboratory cages, following which, the insemination status, oviposition success and egg batch size of each female was assessed. The influence of male and female numbers, strain combination and female size were determined using logistic regression, correlation analysis and a simple mechanistic model of male competition for females. Results Male An. gambiae select females on the basis of size because of much greater fecundity among large females. Even under conditions where large numbers of males must compete for a smaller number of females, the largest females are more likely to become inseminated, to successfully oviposit and to produce large egg batches. Conclusions Sexual selection, on the basis of size, could either promote or limit the spread of malaria-refractory genes into wild populations and needs to be considered in the continued development and eventual release of transgenic vectors. Fundamental studies of behavioural ecology in malaria vectors such as An. gambiae can have important implications for malaria control and should be prioritised for more extensive investigation in the future.

  16. A Consistent Pricing Model for Index Options and Volatility Derivatives

    DEFF Research Database (Denmark)

    Kokholm, Thomas

    on the underlying asset. The model has the convenient feature of decoupling the vanilla skews from spot/volatility correlations and allowing for different conditional correlations in large and small spot/volatility moves. We show that our model can simultaneously fit prices of European options on S&P 500 across......We propose a flexible modeling framework for the joint dynamics of an index and a set of forward variance swap rates written on this index. Our model reproduces various empirically observed properties of variance swap dynamics and enables volatility derivatives and options on the underlying index...

  17. Option Pricing using Realized Volatility

    DEFF Research Database (Denmark)

    Stentoft, Lars Peter

    In the present paper we suggest to model Realized Volatility, an estimate of daily volatility based on high frequency data, as an Inverse Gaussian distributed variable with time varying mean, and we examine the joint properties of Realized Volatility and asset returns. We derive the appropriate...... benchmark model estimated on return data alone. Hence the paper provides evidence on the value of using high frequency data for option pricing purposes....

  18. Option Pricing using Realized Volatility

    DEFF Research Database (Denmark)

    Stentoft, Lars Peter

    In the present paper we suggest to model Realized Volatility, an estimate of daily volatility based on high frequency data, as an Inverse Gaussian distributed variable with time varying mean, and we examine the joint properties of Realized Volatility and asset returns. We derive the appropriate d...... benchmark model estimated on return data alone. Hence the paper provides evidence on the value of using high frequency data for option pricing purposes....

  19. Grid-based mapping: A method for rapidly determining the spatial distributions of small features over very large areas

    Science.gov (United States)

    Ramsdale, Jason D.; Balme, Matthew R.; Conway, Susan J.; Gallagher, Colman; van Gasselt, Stephan A.; Hauber, Ernst; Orgel, Csilla; Séjourné, Antoine; Skinner, James A.; Costard, Francois; Johnsson, Andreas; Losiak, Anna; Reiss, Dennis; Swirad, Zuzanna M.; Kereszturi, Akos; Smith, Isaac B.; Platz, Thomas

    2017-06-01

    The increased volume, spatial resolution, and areal coverage of high-resolution images of Mars over the past 15 years have led to an increased quantity and variety of small-scale landform identifications. Though many such landforms are too small to represent individually on regional-scale maps, determining their presence or absence across large areas helps form the observational basis for developing hypotheses on the geological nature and environmental history of a study area. The combination of improved spatial resolution and near-continuous coverage significantly increases the time required to analyse the data. This becomes problematic when attempting regional or global-scale studies of metre and decametre-scale landforms. Here, we describe an approach for mapping small features (from decimetre to kilometre scale) across large areas, formulated for a project to study the northern plains of Mars, and provide context on how this method was developed and how it can be implemented. Rather than ;mapping; with points and polygons, grid-based mapping uses a ;tick box; approach to efficiently record the locations of specific landforms (we use an example suite of glacial landforms; including viscous flow features, the latitude dependant mantle and polygonised ground). A grid of squares (e.g. 20 km by 20 km) is created over the mapping area. Then the basemap data are systematically examined, grid-square by grid-square at full resolution, in order to identify the landforms while recording the presence or absence of selected landforms in each grid-square to determine spatial distributions. The result is a series of grids recording the distribution of all the mapped landforms across the study area. In some ways, these are equivalent to raster images, as they show a continuous distribution-field of the various landforms across a defined (rectangular, in most cases) area. When overlain on context maps, these form a coarse, digital landform map. We find that grid-based mapping

  20. Food security in an era of economic volatility.

    Science.gov (United States)

    Naylor, Rosamond L; Falcon, Walter P

    2010-01-01

    This article analyzes international commodity price movements, assesses food policies in response to price fluctuations, and explores the food security implications of price volatility on low-income groups. It focuses specifically on measurements, causes, and consequences of recent food price trends, variability around those trends, and price spikes. Combining these three components of price dynamics shows that the variation in real prices post-2000 was substantially greater than that in the 1980s and 1990s, and was approximately equal to the extreme volatility in commodity prices that was experienced in the 1970s. Macro policy, exchange rates, and petroleum prices were important determinants of price variability over 2005–2010, highlighting the new linkages between the agriculture-energy and agriculture-finance markets that affect the world food economy today. These linkages contributed in large part to misguided expectations and uncertainty that drove prices to their peak in 2008. The article also argues that there is a long-lasting effect of price spikes on food policy around the world, often resulting in self-sufficiency policies that create even more volatility in international markets. The efforts by governments to stabilize prices frequently contribute to even greater food insecurity among poor households, most of which are in rural areas and survive on the margin of net consumption and net production. Events of 2008—and more recently in 2010—underscore the impact of price variability for food security and the need for refocused policy approaches to prevent and mitigate price spikes.

  1. Standard Test Method for Determining Solar or Photopic Reflectance, Transmittance, and Absorptance of Materials Using a Large Diameter Integrating Sphere

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    1987-01-01

    1.1 This test method covers the measurement of the absolute total solar or photopic reflectance, transmittance, or absorptance of materials and surfaces. Although there are several applicable test methods employed for determining the optical properties of materials, they are generally useful only for flat, homogeneous, isotropic specimens. Materials that are patterned, textured, corrugated, or are of unusual size cannot be measured accurately using conventional spectrophotometric techniques, or require numerous measurements to obtain a relevant optical value. The purpose of this test method is to provide a means for making accurate optical property measurements of spatially nonuniform materials. 1.2 This test method is applicable to large specimens of materials having both specular and diffuse optical properties. It is particularly suited to the measurement of the reflectance of opaque materials and the reflectance and transmittance of semitransparent materials including corrugated fiber-reinforced plastic, ...

  2. Volatile signals during pregnancy.

    Science.gov (United States)

    Vaglio, Stefano

    2010-01-01

    Scents play a key role in mediating reproductive interactions in many vertebrates including mammals. Nowadays, several studies indicate that humans seem to use remarkably olfactory communication and are even able to produce and perceive pheromones. Furthermore, over the past several years, it became increasingly clear that pheromone-like chemical signals probably play a role in offspring identification and mother recognition. Recently developed technical procedures (solid-phase microextraction and dynamic headspace extraction) now allow investigators to characterize volatile compounds with high reliability. We analyzed the volatile compounds in sweat patch samples collected from the para-axillary and nipple-areola regions of women during pregnancy and after childbirth. We hypothesized that, at the time of birth and during the first weeks of life, the distinctive olfactory pattern of the para-axillary area is probably useful to newborn babies for recognizing and distinguishing their own mother, whereas the characteristic pattern of the nipple-areola region is probably useful as a guide to nourishment.

  3. Molecular plant volatile communication.

    Science.gov (United States)

    Holopainen, Jarmo K; Blande, James D

    2012-01-01

    Plants produce a wide array of volatile organic compounds (VOCs) which have multiple functions as internal plant hormones (e.g., ethylene, methyl jasmonate and methyl salicylate), in communication with conspecific and heterospecific plants and in communication with organisms of second (herbivores and pollinators) and third (enemies of herbivores) trophic levels. Species specific VOCs normally repel polyphagous herbivores and those specialised on other plant species, but may attract specialist herbivores and their natural enemies, which use VOCs as host location cues. Attraction of predators and parasitoids by VOCs is considered an evolved indirect defence, whereby plants are able to indirectly reduce biotic stress caused by damaging herbivores. In this chapter we review these interactions where VOCs are known to play a crucial role. We then discuss the importance of volatile communication in self and nonself detection. VOCs are suggested to appear in soil ecosystems where distinction of own roots from neighbours roots is essential to optimise root growth, but limited evidence of above-ground plant self-recognition is available.

  4. Supercritical fluid extraction of volatile and non-volatile compounds from Schinus molle L.

    Directory of Open Access Journals (Sweden)

    M. S. T. Barroso

    2011-06-01

    Full Text Available Schinus molle L., also known as pepper tree, has been reported to have antimicrobial, antifungal, anti-inflammatory, antispasmodic, antipyretic, antitumoural and cicatrizing properties. This work studies supercritical fluid extraction (SFE to obtain volatile and non-volatile compounds from the aerial parts of Schinus molle L. and the influence of the process on the composition of the extracts. Experiments were performed in a pilot-scale extractor with a capacity of 1 L at pressures of 9, 10, 12, 15 and 20 MPa at 323.15 K. The volatile compounds were obtained by CO2 supercritical extraction with moderate pressure (9 MPa, whereas the non-volatile compounds were extracted at higher pressure (12 to 20 MPa. The analysis of the essential oil was carried out by GC-MS and the main compounds identified were sabinene, limonene, D-germacrene, bicyclogermacrene, and spathulenol. For the non-volatile extracts, the total phenolic content was determined by the Folin-Ciocalteau method. Moreover, one of the goals of this study was to compare the experimental data with the simulated yields predicted by a mathematical model based on mass transfer. The model used requires three adjustable parameters to predict the experimental extraction yield curves.

  5. Determination of the State of Strain of Large Floating Covers Using Unmanned Aerial Vehicle (UAV) Aided Photogrammetry.

    Science.gov (United States)

    Ong, Wern Hann; Chiu, Wing Kong; Kuen, Thomas; Kodikara, Jayantha

    2017-07-28

    Floating covers used in waste water treatment plants are one of the many structures formed with membrane materials. These structures are usually large and can spread over an area measuring 470 m × 170 m. The aim of this paper is to describe recent work to develop an innovative and effective approach for structural health monitoring (SHM) of such large membrane-like infrastructure. This paper will propose a potentially cost-effective non-contact approach for full-field strain and stress mapping using an unmanned aerial vehicle (UAV) mounted with a digital camera and a global positioning system (GPS) tracker. The aim is to use the images acquired by the UAV to define the geometry of the floating cover using photogrammetry. In this manner, any changes in the geometry of the floating cover due to forces acting beneath resulting from its deployment and usage can be determined. The time-scale for these changes is in terms of weeks and months. The change in the geometry can be implemented as input conditions to a finite element model (FEM) for stress prediction. This will facilitate the determination of the state of distress of the floating cover. This paper investigates the possibility of using data recorded from a UAV to predict the strain level and assess the health of such structures. An investigation was first conducted on a laboratory sized membrane structure instrumented with strain gauges for comparison against strains, which were computed from 3D scans of the membrane geometry. Upon validating the technique in the laboratory, it was applied to a more realistic scenario: an outdoor test membrane structure and capable UAV were constructed to see if the shape of the membrane could be computed. The membrane displacements were then used to calculate the membrane stress and strain, state demonstrating a new way to perform structural health monitoring on membrane structures.

  6. DETERMINATION OF 237NP AND PU ISOTOPES IN LARGE SOIL SAMPLES BY INDUCTIVELY COUPLED PLASMA MASS SPECTROMETRY

    Energy Technology Data Exchange (ETDEWEB)

    Maxwell, S.

    2010-07-26

    A new method for the determination of {sup 237}Np and Pu isotopes in large soil samples has been developed that provides enhanced uranium removal to facilitate assay by inductively coupled plasma mass spectrometry (ICP-MS). This method allows rapid preconcentration and separation of plutonium and neptunium in large soil samples for the measurement of {sup 237}Np and Pu isotopes by ICP-MS. {sup 238}U can interfere with {sup 239}Pu measurement by ICP-MS as {sup 238}UH{sup +} mass overlap and {sup 237}Np via {sup 238}U peak tailing. The method provides enhanced removal of uranium by separating Pu and Np initially on TEVA Resin, then transferring Pu to DGA resin for additional purification. The decontamination factor for removal of uranium from plutonium for this method is greater than 1 x 10{sup 6}. Alpha spectrometry can also be applied so that the shorter-lived {sup 238}Pu isotope can be measured successfully. {sup 239}Pu, {sup 242}Pu and {sup 237}Np were measured by ICP-MS, while {sup 236}Pu and {sup 238}Pu were measured by alpha spectrometry.

  7. Volatile diterpene emission from dominant conifers in Japan

    Directory of Open Access Journals (Sweden)

    S. N. Matsunaga

    2011-07-01

    Full Text Available Reactive volatile organic compounds (VOCs are known to affect atmospheric chemistry, especially biogenic VOCs (BVOCs which have a significant impact on regional air quality due to their large emission rates and high reactivities. Diterpenes (Kaur-16-ene and a diterpene likely to be Hibaene were detected in all of the 205 enclosure air samples collected over multiple seasons at two different sites from Cryptomeria japonica and Chamaecyparis obtusa trees, the dominant coniferous trees in Japan. The emission rate of Kaur-16-ene, was determined to be from 0.01 to 7.1 μg dwg−1 h−1 (average: 0.61 μg dwg−1 h−1 by branch enclosure measurements and solid phase – liquid extraction techniques. The emission rate was an order of magnitude higher than that of monoterpenes which are known to comprise a major portion of total BVOC emissions. In addition, total emission of Kaur-16-ene at 30 °C was estimated to be comparable to that of total anthropogenic VOC emissions. To our knowledge, this is the first report of volatile diterpene emissions from trees.

  8. Volatile diterpene emission from dominant conifers in Japan

    Science.gov (United States)

    Matsunaga, S. N.; Chatani, S.; Nakatsuka, S.; Kusumoto, D.; Kubota, K.; Utsumi, Y.; Enoki, T.; Tani, A.; Hiura, T.

    2011-07-01

    Reactive volatile organic compounds (VOCs) are known to affect atmospheric chemistry, especially biogenic VOCs (BVOCs) which have a significant impact on regional air quality due to their large emission rates and high reactivities. Diterpenes (Kaur-16-ene and a diterpene likely to be Hibaene) were detected in all of the 205 enclosure air samples collected over multiple seasons at two different sites from Cryptomeria japonica and Chamaecyparis obtusa trees, the dominant coniferous trees in Japan. The emission rate of Kaur-16-ene, was determined to be from 0.01 to 7.1 μg dwg-1 h-1 (average: 0.61 μg dwg-1 h-1) by branch enclosure measurements and solid phase - liquid extraction techniques. The emission rate was an order of magnitude higher than that of monoterpenes which are known to comprise a major portion of total BVOC emissions. In addition, total emission of Kaur-16-ene at 30 °C was estimated to be comparable to that of total anthropogenic VOC emissions. To our knowledge, this is the first report of volatile diterpene emissions from trees.

  9. A segmental labeling strategy for unambiguous determination of domain-domain interactions of large multi-domain proteins

    Energy Technology Data Exchange (ETDEWEB)

    Chen Jianglei; Wang Jianjun, E-mail: jjwang@med.wayne.edu [Wayne State University, Department of Biochemistry and Molecular Biology, School of Medicine (United States)

    2011-08-15

    NMR structural determination of large multi-domain proteins is a challenging task due to significant spectral overlap with a particular difficulty in unambiguous identification of domain-domain interactions. Segmental labeling is a NMR strategy that allows for isotopically labeling one domain and leaves the other domain unlabeled. This significantly simplifies spectral overlaps and allows for quick identification of domain-domain interaction. Here, a novel segmental labeling strategy is presented for detection of inter-domain NOEs. To identify domain-domain interactions in human apolipoprotein E (apoE), a multi-domain, 299-residues {alpha}-helical protein, on-column expressed protein ligation was utilized to generate a segmental-labeled apoE samples in which the N-terminal (NT-) domain was {sup 2}H(99%)/{sup 15}N-labeled whereas the C-terminal (CT-) domain was either {sup 15}N- or {sup 15}N/{sup 13}C-labeled. 3-D {sup 15}N-edited NOESY spectra of these segmental-labeled apoE samples allow for direct observation of the inter-domain NOEs between the backbone amide protons of the NT-domain and the aliphatic protons of the CT-domain. This straightforward approach permits unambiguous identification of 78 inter-domain NOEs, enabling accurate definition of the relative positions of both the NT- and the CT-domains and determination of the NMR structure of apoE.

  10. Prevalence and determinants of child maltreatment among high school students in Southern China: A large scale school based survey

    Directory of Open Access Journals (Sweden)

    Chen WQ

    2008-09-01

    Full Text Available Abstract Background Child maltreatment can cause significant physical and psychological problems. The present study aimed to investigate the prevalence and determinants of child maltreatment in Guangzhou, China, where such issues are often considered a taboo subject. Methods A school-based survey was conducted in southern China in 2005. 24 high schools were selected using stratified random sampling strategy based on their districts and bandings. The self-administered validated Chinese version of parent-child Conflict Tactics Scale (CTSPC was used as the main assessment tool to measure the abusive experiences encountered by students in the previous six months. Results The response rate of this survey was 99.7%. Among the 6592 responding students, the mean age was 14.68. Prevalence of parental psychological aggression, corporal punishment, severe and very serve physical maltreatment in the past 6 months were 78.3%, 23.2%, 15.1% and 2.8% respectively. The prevalence of sexual abuse is 0.6%. The most commonly cited reasons for maltreatment included 'disobedience to parents', 'poor academic performance', and 'quarrelling between parents'. Age, parental education, places of origins and types of housing were found to be associated with physical maltreatments whereas gender and fathers' education level were associated with sexual abuse. Conclusion Though largely unspoken, child maltreatment is a common problem in China. Identification of significant determinants in this study can provide valuable information for teachers and health professionals so as to pay special attention to those at-risk children.

  11. Parametric Portfolio Policies with Common Volatility Dynamics

    OpenAIRE

    Ergemen, Yunus Emre; Taamouti, Abderrahim

    2015-01-01

    A parametric portfolio policy function is considered that incorporates common stock volatility dynamics to optimally determine portfolio weights. Reducing dimension of the traditional portfolio selection problem significantly, only a number of policy parameters corresponding to first- and second-order characteristics are estimated based on a standard method-of-moments technique. The method, allowing for the calculation of portfolio weight and return statistics, is illustrated with an empirica...

  12. An objective approach to determining the weight ranges of prey preferred by and accessible to the five large African carnivores.

    Directory of Open Access Journals (Sweden)

    Hayley S Clements

    Full Text Available Broad-scale models describing predator prey preferences serve as useful departure points for understanding predator-prey interactions at finer scales. Previous analyses used a subjective approach to identify prey weight preferences of the five large African carnivores, hence their accuracy is questionable. This study uses a segmented model of prey weight versus prey preference to objectively quantify the prey weight preferences of the five large African carnivores. Based on simulations of known predator prey preference, for prey species sample sizes above 32 the segmented model approach detects up to four known changes in prey weight preference (represented by model break-points with high rates of detection (75% to 100% of simulations, depending on number of break-points and accuracy (within 1.3±4.0 to 2.7±4.4 of known break-point. When applied to the five large African carnivores, using carnivore diet information from across Africa, the model detected weight ranges of prey that are preferred, killed relative to their abundance, and avoided by each carnivore. Prey in the weight ranges preferred and killed relative to their abundance are together termed "accessible prey". Accessible prey weight ranges were found to be 14-135 kg for cheetah Acinonyx jubatus, 1-45 kg for leopard Panthera pardus, 32-632 kg for lion Panthera leo, 15-1600 kg for spotted hyaena Crocuta crocuta and 10-289 kg for wild dog Lycaon pictus. An assessment of carnivore diets throughout Africa found these accessible prey weight ranges include 88±2% (cheetah, 82±3% (leopard, 81±2% (lion, 97±2% (spotted hyaena and 96±2% (wild dog of kills. These descriptions of prey weight preferences therefore contribute to our understanding of the diet spectrum of the five large African carnivores. Where datasets meet the minimum sample size requirements, the segmented model approach provides a means of determining, and comparing, the prey weight range preferences of any carnivore

  13. Consistent ranking of volatility models

    DEFF Research Database (Denmark)

    Hansen, Peter Reinhard; Lunde, Asger

    2006-01-01

    We show that the empirical ranking of volatility models can be inconsistent for the true ranking if the evaluation is based on a proxy for the population measure of volatility. For example, the substitution of a squared return for the conditional variance in the evaluation of ARCH-type models can...

  14. Political institutions and economic volatility

    NARCIS (Netherlands)

    Klomp, Jeroen; de Haan, Jakob

    2009-01-01

    We examine the effect of political 'institutions' on economic growth volatility, using data from more than 100 countries over the period 1960 to 2005, taking into account various control variables as suggested in previous studies. Our indicator of volatility is the relative standard deviation of the

  15. The Volatile Fatty Acids and Lactic Acid in Silage Determined Quickly by the Gas Chromatography%气相色谱法同时快速测定青贮饲料中的挥发性脂肪酸及乳酸

    Institute of Scientific and Technical Information of China (English)

    高晓松

    2012-01-01

    目前,国内外测定乳酸和挥发性脂肪酸(VFA)的方法主要是气相色谱法,一般情况下是对乳酸和挥发性脂肪酸分别进行测定,青贮饲料中乳酸和挥发性脂肪酸的同时测定未见报道。采用简便的甲酯衍生化方法,利用气相色谱填充柱.探索出一种能同时快速测定青贮饲料中乳酸和挥发性脂肪酸的方法,以期为青贮饲料的研究提供可靠的分析技术。%At present gas chromatography is considered as one of the most reliable methods in measuring lactic acid and volatile fatty acid domestically and abroad. Lactic acid and volatile fatty acid were determined respectively in general method. Lactic acid and volatile fatty acid were determined simultaneously in corn ensilage have not been reported. Using a simple and convenient method for derivative process of Methyl in this paper, a packed column was used in gas chromatography, exploring a new way of a rapid method for simultaneous determination of lactic acid and volatile fatty acid in corn ensilage to provide a reliable analysis technology for the research on corn ensilage.

  16. Speculation and volatility spillover in the crude oil and agricultural commodity markets: A Bayesian analysis

    Energy Technology Data Exchange (ETDEWEB)

    Du Xiaodong, E-mail: xdu23@wisc.ed [Department of Agricultural and Applied Economics, University of Wisconsin-Madison, WI (United States); Yu, Cindy L., E-mail: cindyyu@iastate.ed [Department of Statistics, Iowa State University, IA (United States); Hayes, Dermot J., E-mail: dhayes@iastate.ed [Department of Economics and Department of Finance, Iowa State University, IA (United States)

    2011-05-15

    This paper assesses factors that potentially influence the volatility of crude oil prices and the possible linkage between this volatility and agricultural commodity markets. Stochastic volatility models are applied to weekly crude oil, corn, and wheat futures prices from November 1998 to January 2009. Model parameters are estimated using Bayesian Markov Chain Monte Carlo methods. Speculation, scalping, and petroleum inventories are found to be important in explaining the volatility of crude oil prices. Several properties of crude oil price dynamics are established, including mean-reversion, an asymmetry between returns and volatility, volatility clustering, and infrequent compound jumps. We find evidence of volatility spillover among crude oil, corn, and wheat markets after the fall of 2006. This can be largely explained by tightened interdependence between crude oil and these commodity markets induced by ethanol production.

  17. Emerging non-volatile memories

    CERN Document Server

    Hong, Seungbum; Wouters, Dirk

    2014-01-01

    This book is an introduction to the fundamentals of emerging non-volatile memories and provides an overview of future trends in the field. Readers will find coverage of seven important memory technologies, including Ferroelectric Random Access Memory (FeRAM), Ferromagnetic RAM (FMRAM), Multiferroic RAM (MFRAM), Phase-Change Memories (PCM), Oxide-based Resistive RAM (RRAM), Probe Storage, and Polymer Memories. Chapters are structured to reflect diffusions and clashes between different topics. Emerging Non-Volatile Memories is an ideal book for graduate students, faculty, and professionals working in the area of non-volatile memory. This book also: Covers key memory technologies, including Ferroelectric Random Access Memory (FeRAM), Ferromagnetic RAM (FMRAM), and Multiferroic RAM (MFRAM), among others. Provides an overview of non-volatile memory fundamentals. Broadens readers' understanding of future trends in non-volatile memories.

  18. Measurement of volatile organic compounds in human blood.

    OpenAIRE

    Ashley, D L; Bonin, M A; Cardinali, F L; McCraw, J. M.; Wooten, J V

    1996-01-01

    Volatile organic compounds (VOCs) are an important public health problem throughout the developed world. Many important questions remain to be addressed in assessing exposure to these compounds. Because they are ubiquitous and highly volatile, special techniques must be applied in the analytical determination of VOCs. The analytical methodology chosen to measure toxicants in biological materials must be well validated and carefully carried out; poor quality assurance can lead to invalid resul...

  19. Hygroscopic behavior of partially volatilized coastal marine aerosols using the volatilization and humidification tandem differential mobility analyzer technique

    Science.gov (United States)

    Johnson, G. R.; Ristovski, Z. D.; D'Anna, B.; Morawska, L.

    2005-10-01

    Coastal marine nucleation, Aitken, and accumulation mode aerosol particles with back trajectories indicative of marine origin were examined using a volatilization and humidification tandem differential mobility analyzer (VHTDMA) to reveal the volatilization temperatures of the various component species. The diameter hygroscopic growth factors of the residue particles were continually examined throughout the volatilization process. In each of the three modes the dominant particle type appeared to be composed of the same four physicochemically distinct species though in different ratios. These species exhibited volatility and hygroscopic behavior consistent with combinations of a volatile organic species, sulfuric acid, ammonium sulfate or bisulfate, iodine oxide, and an insoluble nonvolatile residue. The Aitken and accumulation mode aerosols contain large fractions of the insoluble, volatile, organic-like material, and the volatilization of this species results in a distinct increase in the water volume uptake of the particles. Of the four distinct species, only the sulfuric acid-like species constituted an increasing volume fraction with decreasing particle size. This finding indicates that nucleation mode particles constitute an acidic seed and as such would undergo acid-catalyzed secondary organic aerosol growth at a faster rate. The lack of a nonvolatile hygroscopic residue consistent with sea salt in these particles implies that the aerosolization of seawater is not the dominant production mechanism for these submicrometer coastal marine aerosols.

  20. Water on The Moon, III. Volatiles & Activity

    CERN Document Server

    Crotts, Arlin

    2012-01-01

    For centuries some scientists have argued that there is activity on the Moon (or water, as recounted in Parts I & II), while others have thought the Moon is simply a dead, inactive world. The question comes in several forms: is there a detectable atmosphere? Does the surface of the Moon change? What causes interior seismic activity? From a more modern viewpoint, we now know that as much carbon monoxide as water was excavated during the LCROSS impact, as detailed in Part I, and a comparable amount of other volatiles were found. At one time the Moon outgassed prodigious amounts of water and hydrogen in volcanic fire fountains, but released similar amounts of volatile sulfur (or SO2), and presumably large amounts of carbon dioxide or monoxide, if theory is to be believed. So water on the Moon is associated with other gases. We review what is known (and touch on what is unknown) about outgassing of various gases from the Moon.

  1. Volatile properties of atmospheric aerosols during nucleation events at Pune, India

    Indian Academy of Sciences (India)

    P Murugavel; D M Chate

    2011-06-01

    Continuous measurements of aerosol size distributions in the mid-point diameter range 20.5–500 nm were made from October 2005 to March 2006 at Pune (18° 32′N, 73° 51′E), India using Scanning Mobility Particle Sizer (SMPS). Volatilities of atmospheric aerosols were also measured at 40°, 125°, 175°, 300° and 350°C temperatures with Thermodenuder–SMPS coupled system to determine aerosol volatile fractions. Aerosols in nucleated, CCN and accumulated modes are characterized from the measured percentage of particles volatized at 40°, 125°, 175°, 300° and 350°C temperatures. Averaged monthly aerosol concentration is at its maximum in November and gradually decreases to its minimum at the end of March. The diurnal variations of aerosol concentrations gradually decrease in the night and in early morning hours (0400–0800 hr). However, concentration attains minimum in its variations in the noon (1400–1600 hr) due to higher ventilation factor (product of mixing height and wind speed). The half an hour averaged diurnal variation of aerosol number concentration shows about 5 to 10-fold increase despite the ventilation factor at higher side before 1200 hr. This sudden increase in aerosol concentrations is linked with prevailing conditions for nucleation bursts. The measurement of volatile fraction of ambient aerosols reveals that there are large number of highly volatile particles in the Aitken mode in the morning hours and these volatile fractions of aerosols at temperatures > 150°C are of ammonium chloride and ammonium sulfate, acetic and formic acids.

  2. Governmentally amplified output volatility

    Science.gov (United States)

    Funashima, Yoshito

    2016-11-01

    Predominant government behavior is decomposed by frequency into several periodic components: updating cycles of infrastructure, Kuznets cycles, fiscal policy over business cycles, and election cycles. Little is known, however, about the theoretical impact of such cyclical behavior in public finance on output fluctuations. Based on a standard neoclassical growth model, this study intends to examine the frequency at which public investment cycles are relevant to output fluctuations. We find an inverted U-shaped relationship between output volatility and length of cycle in public investment. This implies that periodic behavior in public investment at a certain frequency range can cause aggravated output resonance. Moreover, we present an empirical analysis to test the theoretical implication, using the U.S. data in the period from 1968 to 2015. The empirical results suggest that such resonance phenomena change from low to high frequency.

  3. Volatility Exposure for Strategic Asset Allocation

    OpenAIRE

    Briere, Marie; Burgues, Alexandre; Signori, Ombretta

    2010-01-01

    The authors examine the advantages of incorporating strategic exposure to equity volatility into the investment opportunity set of a long-term equity investor. They consider two standard volatility investments: implied volatility and volatility risk premium strategies. An analytical framework, which offers pragmatic solutions for long-term investors who seek exposure to volatility, is used to calibrate and assess the risk-return profiles of portfolios. The benefit of volatility exposure for a...

  4. Determination of 26 Kinds of Volatile Organic Compounds in Water with Purge and Trap/Gas Chromatography-Mass Spectrometry%吹扫捕集/GC-MS法测定水中26种挥发性有机物

    Institute of Scientific and Technical Information of China (English)

    张芹; 曾凡海; 王少青

    2013-01-01

    采用吹扫捕集/气相色谱-质谱(GC-MS)法测定水中26种挥发性有机物(VOCs),并对吹扫捕集条件进行优化,分析了吹扫温度和吹扫时间、解吸温度和解吸时间对吹扫捕集效率的影响.分析结果表明,在此条件下,挥发性有机物的线性相关系数为0.999 0~0.999 9,平均加标回收率为94.0%~108.3%,相对标准偏差为2.4%~6.1%,具有较好的线性关系,准确度和精密度;方法检出限为0.03~0.28 μg/L,远低于《地表水环境质量标准》(GB 3838-2002)中限值.%Purge and trap/gas chromatography-mass spectrometry was used to determine 26 volatile organic compounds (VOCs) in water, and the conditions of the method were optimized. The influences of purge temperature, purge time, desorption temperature and desorption time on the efficiency of purge and trap were analyzed. Under the optimized conditions, this method had good linear relations, accuracy and precision, with a linear correlation coefficient of VOCs of 0. 999 0~0. 999 9, an average recovery of 94. 0%~ 108. 3% , a relative standard deviation of 2. 4%~6. 1% and a detection limit of 0. 03~0. 28 μg/L, which is much lower than the mid-limited value stipulated in Environmental Quality Standards for Surface Water (GB 3838-2002).

  5. Large-scale determinants of diversity across Spanish forest habitats: accounting for model uncertainty in compositional and structural indicators

    Energy Technology Data Exchange (ETDEWEB)

    Martin-Quller, E.; Torras, O.; Alberdi, I.; Solana, J.; Saura, S.

    2011-07-01

    An integral understanding of forest biodiversity requires the exploration of the many aspects it comprises and of the numerous potential determinants of their distribution. The landscape ecological approach provides a necessary complement to conventional local studies that focus on individual plots or forest ownerships. However, most previous landscape studies used equally-sized cells as units of analysis to identify the factors affecting forest biodiversity distribution. Stratification of the analysis by habitats with a relatively homogeneous forest composition might be more adequate to capture the underlying patterns associated to the formation and development of a particular ensemble of interacting forest species. Here we used a landscape perspective in order to improve our understanding on the influence of large-scale explanatory factors on forest biodiversity indicators in Spanish habitats, covering a wide latitudinal and attitudinal range. We considered six forest biodiversity indicators estimated from more than 30,000 field plots in the Spanish national forest inventory, distributed in 213 forest habitats over 16 Spanish provinces. We explored biodiversity response to various environmental (climate and topography) and landscape configuration (fragmentation and shape complexity) variables through multiple linear regression models (built and assessed through the Akaike Information Criterion). In particular, we took into account the inherent model uncertainty when dealing with a complex and large set of variables, and considered different plausible models and their probability of being the best candidate for the observed data. Our results showed that compositional indicators (species richness and diversity) were mostly explained by environmental factors. Models for structural indicators (standing deadwood and stand complexity) had the worst fits and selection uncertainties, but did show significant associations with some configuration metrics. In general

  6. Determination of counterfeit medicines by Raman spectroscopy: Systematic study based on a large set of model tablets.

    Science.gov (United States)

    Neuberger, Sabine; Neusüß, Christian

    2015-08-10

    In the last decade, counterfeit pharmaceutical products have become a widespread issue for public health. Raman spectroscopy which is easy, non-destructive and information-rich is particularly suitable as screening method for fast characterization of chemicals and pharmaceuticals. Combined with chemometric techniques, it provides a powerful tool for the analysis and determination of counterfeit medicines. Here, for the first time, a systematic study of the benefits and limitations of Raman spectroscopy for the analysis of pharmaceutical samples on a large set of model tablets, varying with respect to chemical and physical properties, was performed. To discriminate between the different mixtures, a combination of dispersive Raman spectroscopy performing in backscattering mode and principal component analysis was used. The discrimination between samples with different coatings, a varying amount of active pharmaceutical ingredients and a diversity of excipients were possible. However, it was not possible to distinguish between variations of the press power, mixing quality and granulation. As a showcase, the change in Raman signals of commercial acetylsalicylic acid effervescent tablets due to five different storage conditions was monitored. It was possible to detect early small chemical changes caused by inappropriate storage conditions. These results demonstrate that Raman spectroscopy combined with multivariate data analysis provides a powerful methodology for the fast and easy characterization of genuine and counterfeit medicines. Copyright © 2015 Elsevier B.V. All rights reserved.

  7. Use of allele-specific FAIRE to determine functional regulatory polymorphism using large-scale genotyping arrays

    DEFF Research Database (Denmark)

    Smith, Frank Andrew; Howard, Philip; Shah, Sonia;

    2012-01-01

    identified an allele-specific regulatory polymorphism within NR1H3 (coding for LXR-α), rs7120118, coinciding with a previously GWAS-identified SNP for HDL-C levels. This finding was confirmed using FAIRE-gen with the 200,000 SNP Illumina Metabochip and verified with the established method of TaqMan allelic...... variants, we describe the technique of allele-specific FAIRE, utilising large-scale genotyping technology (FAIRE-gen) to determine allelic effects on chromatin accessibility and regulatory potential. FAIRE-gen was explored using lymphoblastoid cells and the 50,000 SNP Illumina CVD BeadChip. The technique...... discrimination. Examination of this SNP in two prospective Caucasian cohorts comprising 15,000 individuals confirmed the association with HDL-C levels (combined beta = 0.016; p = 0.0006), and analysis of gene expression identified an allelic association with LXR-α expression in heart tissue. Using increasingly...

  8. The application of APTEA experiment design to the experiment for determining information density of large scale display panel

    Energy Technology Data Exchange (ETDEWEB)

    Sim, Bong Sik; Oh, In Suk; Cha, Kyung Ho; Lee, Hyun Cheol [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

    1995-06-01

    APTEA experiment design was developed for the purpose of enhancing the availability of integrated test facility in 1994, and is composed of 5 phases including 28 contents. We applied APTEA experiment design to a preliminary human factors experiment for the determination of information density on a large scale display panel in order to confirm the usability of APTEA before utilizing it with integrated test facility. As results, we verified the easiness on the use of APTEA experiment design and identified points to be considered as follows. - Each phase and content doesn`t demand the same duration and level of work. Therefore it is unnecessary for experimenter to give same weight to all the phases and contents. - Filling up the phases and contents of ATPEA require various knowledge such as programming, human factors principles, experiment design. So a multidisciplinary team is desired in using APTEA experiment design. - It will be difficult to clearly discern the differences among contents in some experiments. In this case, the integration of several contents is desirable. 5 tabs., 2 figs., 5 refs. (Author) .new.

  9. Large Isoform of Mammalian Relative of DnaJ is a Major Determinant of Human Susceptibility to HIV-1 Infection

    Directory of Open Access Journals (Sweden)

    Yu-Ping Chiang

    2014-12-01

    Full Text Available Individual differences in susceptibility to human immunodeficiency virus type 1 (HIV-1 infection have been of interest for decades. We aimed to determine the contribution of large isoform of Mammalian DnaJ (MRJ-L, a HIV-1 Vpr-interacting cellular protein, to this natural variation. Expression of MRJ-L in monocyte-derived macrophages was significantly higher in HIV-infected individuals (n = 31 than their uninfected counterparts (n = 27 (p = 0.009. Fifty male homosexual subjects (20 of them are HIV-1 positive were further recruited to examine the association between MRJ-L levels and occurrence of HIV infection. Bayesian multiple logistic regression revealed that playing a receptive role and increased levels of MRJ-L in macrophages were two risk factors for HIV-1 infection. A 1% rise in MRJ-L expression was associated with a 1.13 fold (95% CrI 1.06–1.29 increase in odds of contracting HIV-1 infection. Ex vivo experiments revealed that MRJ-L facilitated Vpr-dependent nuclear localization of virus. Infection of macrophage-tropic strain is a critical step in HIV-1 transmission. MRJ-L is a critical factor in this process; hence, subjects with higher macrophage MRJ-L levels are more vulnerable to HIV-1 infection.

  10. Exploring heterogeneous market hypothesis using realized volatility

    Science.gov (United States)

    Chin, Wen Cheong; Isa, Zaidi; Mohd Nor, Abu Hassan Shaari

    2013-04-01

    This study investigates the heterogeneous market hypothesis using high frequency data. The cascaded heterogeneous trading activities with different time durations are modelled by the heterogeneous autoregressive framework. The empirical study indicated the presence of long memory behaviour and predictability elements in the financial time series which supported heterogeneous market hypothesis. Besides the common sum-of-square intraday realized volatility, we also advocated two power variation realized volatilities in forecast evaluation and risk measurement in order to overcome the possible abrupt jumps during the credit crisis. Finally, the empirical results are used in determining the market risk using the value-at-risk approach. The findings of this study have implications for informationally market efficiency analysis, portfolio strategies and risk managements.

  11. Determination of Volatile Phenolic Compounds in Baijiu by GC-MS%气相色谱-质谱法测定白酒中挥发性酚类物质

    Institute of Scientific and Technical Information of China (English)

    张倩

    2016-01-01

    用液液萃取作为前处理方法,建立气相色谱-质谱联用法测定白酒中10种挥发性酚类物质含量的方法.该方法检测得出的质谱图在谱库进行检索,准确地对10种挥发性酚类物质进行定性、定量分析.加标回收率为83.9%~101.2%,RSD值为1.1%~2.9%.定性、定量准确度较高,重复性好.实验结果表明,该方法适用于白酒中挥发性酚类化合物的研究.%GC-MS was used to detect the content of 10 kinds of volatile phenolic compounds in Baijiu pretreated by liquid-liquid extraction. Library searching of the obtained mass spectra was performed to achieve more accurate quantitative and qualitative analysis of the 10 volatile phenolic compounds. The recovery rate was 83.9%~101.2%, and RSD was 1.1%~2.9%. Qualitative and quantitative accuracy was high with satisfactory repeatability. The experimental results proved that the method was suitable for the study of volatile phenol compounds in Bai-jiu.

  12. Elicitors of tansy volatiles from cotton leafworm larval oral secretion.

    Science.gov (United States)

    Mack, Lienhard; Gros, Petra; Burkhardt, Jens; Seifert, Karlheinz

    2013-12-01

    The feeding of Spodoptera littoralis and Autographa gamma caterpillars on tansy leaves led to a complete different release of volatile monoterpenes, sesquiterpenes, and hexenyl alkanoates. Volatiles were collected from S. littoralis and A. gamma larvae damaged, mechanically wounded, and excised tansy leaves by closed loop stripping analysis. The qualitative and quantitative determination of the volatiles were done by GC-MS- and GC-measurements. The oligosaccharides sucrose, raffinose, stachyose, and verbascose have been detected in oral secretion of the caterpillars of the cotton leafworm S. littoralis. When applied to damaged leaves of tansy plants, these oligosaccharides induce the tansy leaves to emit a similar volatile blend as the feeding of S. littoralis larvae.

  13. Equation-by-Equation Estimation of Multivariate Periodic Electricity Price Volatility

    OpenAIRE

    Escribano, Alvaro; Sucarrat, Genaro

    2016-01-01

    Electricity prices are characterised by strong autoregressive persistence, periodicity (e.g. intraday, day-of-the week and month-of-the-year effects), large spikes or jumps, GARCH and -- as evidenced by recent findings -- periodic volatility. We propose a multivariate model of volatility that decomposes volatility multiplicatively into a non-stationary (e.g. periodic) part and a stationary part with log-GARCH dynamics. Since the model belongs to the log-GARCH class, the model is robust to ...

  14. Determination of 11 kinds of volatile organic compounds in drinking water by headspace gas chromatography%饮用水中11种挥发性有机物的顶空-气相色谱测定法

    Institute of Scientific and Technical Information of China (English)

    余胜兵; 朱炳辉; 刘静; 许瑛华; 吕芬; 钟秀华

    2013-01-01

    [Objective] To establish a method for determination of 11 kinds of volatile organic compounds (VOCs) such as methyl-ene chloride, benzene, toluene, 1,2 - dichloroethane in drinking water by headspace gas chromatography. [Methods]Sample solution with 0. 30 g/ml NaCl was equilibrated at 65 ℃ for 30 min, the VOCs were separated by HP-Wax capillary column, then detected by hydrogen flame ionization detector (FID) and quantified by external standard method. [Results] The linear range of dichlo-romethane, benzene, toluene, 1,2-dichloroethane, ethylbenzene, p-xylene, m-xylene, cumene, o-xylene, chlorobenzene, styrene were 17.4-324, 5.5-97, 4.1-80, 24.5-288.00, 3.6-99, 7.2-80, 6.2-81, 4.1-94, 4.2-80, 6.4-103, 6.2-97 μg/L, respectively. The limit detection range were 1.1-7.4 μg/L (S/N = 3). The recoveries were 85. 8% -107.0% and the relative standard deviations (RSDs) were 1.3%-5. 6% (n =6). [Conclusion] This method is simple, with less matrix interference and high efficiency, suitable for the simultaneous determination of 11 kinds of VOCs in drinking water, and convenient for water quality monitoring at the grassroots units.%目的 建立饮用水中二氯甲烷、苯、甲苯、1,2-二氯乙烷等11种挥发性有机物的顶空-气相色谱法.方法 10 ml样品添加0.30 g NaCl后,在65℃平衡30 min,经顶空进样后,采用Hp-Wax毛细管色谱柱进行分离,以氢火焰离子化检测器进行检测,以保留时间定性,外标法定量.结果 二氯甲烷、苯、甲苯、1,2二氯乙烷、乙苯、对二甲苯、间二甲苯、异丙苯、邻二甲苯、氯苯、苯乙烯的线性范围分别为17.4~ 324、5.5~97、4.1 ~80、24.5~ 288、3.6~ 99、7.2 ~80、6.2 ~81、4.1~94、4.2 ~80、6.4~ 103和6.2~97 μg/L,最低检出浓度为1.1 ~7.4 μg/L,加标回收率为85.8%~107.0%,相对标准偏差(RSD)为1.3%~5.6%(n=6).结论 该分析方法操作简单,基体干扰少,分析效率高,可对饮用水中11种挥发性有机物

  15. Fungal infections of fresh-cut fruit can be detected by the gas chromatography-mass spectrometric identification of microbial volatile organic compounds.

    Science.gov (United States)

    Lloyd, Steven W; Grimm, Casey C; Klich, Maren A; Beltz, Shannon B

    2005-06-01

    There is a large and rapidly growing market for fresh-cut fruit. Microbial volatile organic compounds indicate the presence of fungal or bacterial contamination in fruit. In order to determine whether microbial volatile organic compounds can be used to detect contamination before fruit becomes unmarketable, pieces of cantaloupe, apple, pineapple, and orange were inoculated with a variety of fungal species, incubated at 25 degrees C, then sealed in glass vials. The volatiles were extracted by headspace solid-phase microextraction and analyzed by gas chromatography-mass spectrometry. Forty-five compounds were identified that might serve as unique identifiers of fungal contamination. Fungal contamination can be detected as early as 24 h after inoculation.

  16. Self-reported disability in patients with inflammatory bowel disease largely determined by disease activity and illness perceptions.

    Science.gov (United States)

    van der Have, Mike; Fidder, Herma H; Leenders, Max; Kaptein, Ad A; van der Valk, Mirthe E; van Bodegraven, Ad A; Dijkstra, Gerard; de Jong, Dirk J; Pierik, Marieke; Ponsioen, Cyriel Y; van der Meulen-de Jong, Andrea E; van der Woude, C Janneke; van de Meeberg, Paul C; Romberg-Camps, Mariëlle J L; Clemens, Cees H M; Jansen, Jeroen M; Mahmmod, Nofel; Bolwerk, Clemens J M; Vermeijden, J Reinoud; Siersema, Peter D; Oldenburg, Bas

    2015-02-01

    The inflammatory bowel disease (IBD) disability index has recently been introduced to measure patients' physical, psychological, familial, and social limitations associated with IBD. We assessed factors related to self-reported disability and the relationship between disability and direct health care costs. A large cohort of patients with Crohn's disease (CD) and ulcerative colitis (UC) was prospectively followed for 2 years by 3 monthly web-based questionnaires. At 2 years, patients completed the IBD disability index, with lower score indicating more disability. Linear regression analysis was used to examine the impact of demographics, clinical characteristics, and illness perceptions on self-reported disability. Trends in direct health care costs across the disability severity groups minimal, mild, moderate, and severe, were tested. A total of 554 patients with CD and 424 patients with UC completed the IBD disability index (response rate, 45%). Both clinical characteristics and illness perceptions significantly contributed to self-reported disability (45%-47%, P = 0.000 and 8%-12%, P = 0.000, respectively). Patients with CD scored lower on the self-reported IBD disability index than patients with UC (0.255 versus 3.890, P disease activity, illness identity (higher number of symptoms attributed to IBD), and stronger emotional response. Disease duration and disease phenotype were not associated with self-reported disability. Direct health care costs increased with the worsening of self-reported disability (P = 0.000). More disability was reported by patients with CD than by UC. Self-reported disability in IBD was mainly determined by clinical disease activity and illness perceptions but not by disease duration or disease phenotype.

  17. A see-saw of pre-Columbian boom regions in southern Peru, determined by large-scale circulation changes

    Science.gov (United States)

    Mächtle, B.; Schittek, K.; Forbriger, M.; Schäbitz, F.; Eitel, B.

    2012-04-01

    Environmental changes and cultural transitions during several periods of Peruvian history show a strong coincidence between humid and dry climatic oscillations and the rise and decline of cultures. It is noteworthy, that alternating periods of geo-ecological fragility and stability occurred in time and space between the coastal Nasca region (14.5° S) and the high Andean northern Titicaca basin, just a few hundred kilometers to the east. Based on a multi-proxy palynological and sedimentological approach to reconstruct palaeoenvironmental changes, we found that the Nasca region received a maximum of precipitation during the archaeological boom times of the Early Horizon and the Early Intermediate Period (800 BC - 650 AD, Paracas and Nasca cultures) as well as during the late intermediate period (1150-1450 AD), whereas, in contrast, the Titicaca region further to the south-east experienced drought and cultural depression during that times. During the Middle Horizon (650 - 1150 AD), the Tiwanaku agronomy and culture boomed in the Titicaca region and expanded to the west, contemporaneous with a raised lake level and more humid conditions. In the Nasca region, runoff for irrigation purposes was reduced and less reliable due to drought. Considering a coincidence between environmental and cultural changes, we state that success and decline of civilizations were controlled by hydrological oscillations, triggering fertility as well as a critical loss of natural resources. In response to spatial changing resources, cultural foci were shifted. Therefore, the success of pre-Columbian civilizations was closely coupled to areas of geo-ecological favorability, which were directly controlled by distinct regional impacts of large-scale circulation mechanisms, including El Niño - Southern Oscillation (ENSO). Changes in the position of the intertropical convergence zone (ITCZ) and the Bolivian anticyclone determined meridional shifts in moisture transport across the Andes, which

  18. A Large Eddy Simulation to determine the effect of trees on wind and turbulence over a suburban surface

    Science.gov (United States)

    Egli, P. E.; Giometto, M. G.; Tooke, T. R.; Krayenhoff, S.; Christen, A.; Parlange, M. B.

    2014-12-01

    Robust modeling of flow and turbulence within and over urban canopies is required to properly predict air pollution and dispersion in cities. Trees are an integral part of the urban landscape. In many suburban neighbourhoods, tree cover is 10 to 30% and trees are often taller than buildings. Effects of trees on drag, mean wind and turbulence in cities are not accounted for in current weather, air pollution and dispersion models. Our goal is to use high-resolution Large Eddy Simulations (LES) over a realistic urban canopy to determine the effects of trees on drag, mean wind and turbulence in the urban roughness sublayer (RSL). The simulated area is part of the Sunset-Neighbourhood in Vancouver, Canada. In this area, long-term wind and turbulence measurements are available from instruments on a 28m-tall tower. Further, a three-dimensional point cloud was captured from high precision airborne Light Detection and Ranging (LiDAR), and analyzed to represent the structural characteristics of both buildings and trees at high spatial resolution. Trees are described by location-specific leaf area density (LAD) profiles. LES simulations are performed over a 512 x 512m characteristic subset of the city that contains the tower location and predominant source area. In the LES, buildings are accounted for with an immersed boundary method, adopting a zero level-set distance function to localize the surface, whereas drag forces from trees are parametrized as a function of the height-dependent LAD. Spectra of streamwise and vertical velocity components compare well between tower data and the model data, confirming the good performance of LES in simulations of flow over fully rough surfaces. We show how the presence of trees impacts mean velocity and computed momentum flux profiles; they significantly decrease dispersive terms in the bulk of the flow. The impact of trees on integral length scales in the flow is discussed.

  19. The Application of Methane Clumped Isotope Measurements to Determine the Source of Large Methane Seeps in Alaskan Lakes

    Science.gov (United States)

    Douglas, P. M.; Stolper, D. A.; Eiler, J. M.; Sessions, A. L.; Walter Anthony, K. M.

    2014-12-01

    Natural methane emissions from the Arctic present an important potential feedback to global warming. Arctic methane emissions may come from either active microbial sources or from deep fossil reservoirs released by the thawing of permafrost and melting of glaciers. It is often difficult to distinguish between and quantify contributions from these methane sources based on stable isotope data. Analyses of methane clumped isotopes (isotopologues with two or more rare isotopes such as 13CH3D) can complement traditional stable isotope-based classifications of methane sources. This is because clumped isotope abundances (for isotopically equilibrated systems) are a function of temperature and can be used to identify pathways of methane generation. Additionally, distinctive effects of mixing on clumped isotope abundances make this analysis valuable for determining the origins of mixed gasses. We find large variability in clumped isotope compositions of methane from seeps in several lakes, including thermokarst lakes, across Alaska. At Lake Sukok in northern Alaska we observe the emission of dominantly thermogenic methane, with a formation temperature of at least 100° C. At several other lakes we find evidence for mixing between thermogenic methane and biogenic methane that forms in low-temperature isotopic equilibrium. For example, at Eyak Lake in southeastern Alaska, analysis of three methane samples results in a distinctive isotopic mixing line between a high-temperature end-member that formed between 100-170° C, and a biogenic end-member that formed in isotopic equilibrium between 0-20° C. In this respect, biogenic methane in these lakes resembles observations from marine gas seeps, oil degradation, and sub-surface aquifers. Interestingly, at Goldstream Lake in interior Alaska, methane with strongly depleted clumped-isotope abundances, indicative of disequilibrium gas formation, is found, similar to observations from methanogen culture experiments.

  20. Fetal Environment Is a Major Determinant of the Neonatal Blood Thyroxine Level: Results of a Large Dutch Twin Study.

    Science.gov (United States)

    Zwaveling-Soonawala, Nitash; van Beijsterveldt, Catharina E M; Mesfum, Ertirea T; Wiedijk, Brenda; Oomen, Petra; Finken, Martijn J J; Boomsma, Dorret I; van Trotsenburg, A S Paul

    2015-06-01

    The interindividual variability in thyroid hormone function parameters is much larger than the intraindividual variability, suggesting an individual set point for these parameters. There is evidence to suggest that environmental factors are more important than genetic factors in the determination of this individual set point. This study aimed to quantify the effect of genetic factors and (fetal) environment on the early postnatal blood T4 concentration. This was a classical twin study comparing the resemblance of neonatal screening blood T4 concentrations in 1264 mono- and 2566 dizygotic twin pairs retrieved from the population-based Netherlands Twin Register. Maximum-likelihood estimates of variance explained by genetic and environmental influences were obtained by structural equation modeling in data from full-term and preterm twin pairs. In full-term infants, genetic factors explained 40%/31% of the variance in standardized T4 scores in boys/girls, and shared environment, 27%/22%. The remaining variance of 33%/47% was due to environmental factors not shared by twins. For preterm infants, genetic factors explained 34%/0% of the variance in boys/girls, shared environment 31%/57%, and unique environment 35%/43%. In very preterm twins, no significant contribution of genetic factors was observed. Environment explains a large proportion of the resemblance of the postnatal blood T4 concentration in twin pairs. Because we analyzed neonatal screening results, the fetal environment is the most likely candidate for these environmental influences. Genetic influences on the T4 set point diminished with declining gestational age, especially in girls. This may be due to major environmental influences such as immaturity and nonthyroidal illness in very preterm infants.

  1. Volatile cycling and the thermal evolution of planetary mantle

    Science.gov (United States)

    Sandu, Constantin

    degassing/regassing processes, in agreement with more recent estimates. An important effect of the volatile cycling process is a general negative feedback effect that results in a general trend to adjust the mantle volatile content in time to a value set by the energy balance in the system. As a result, the initial amount of volatile in the mantle is rendered irrelevant for late stage of thermal evolution. In the case of no plate tectonics, the opposite effect takes place: initial volatilization plays an important role through entire evolution. The implications of mantle convection on the stability of the lithosphere were investigated further using the thermal history calculations and numeric simulations. They point to the conclusion that mantle convection induced stress levels increase from the past to the present fact that leads to a greater potential of craton deformation. The main consequence of this trend is that sections of continental lithosphere that have remained stable since the Archean and Proterozoic are becoming progressively more prone to instability in the geologically modern era. After the volatiles are degassed from the mantle, they are cycled through the atmosphere. The interact with the climate influencing the surface temperature, and further controlling the mantle convection. Using a grey radiative-convective model for the atmosphere, we analyzed the feedback relationships between volatiles, especially water, and surface temperature. We showed that large amount of water degassed during a hot, possible melt ocean phase after the planet formation could conserve large amount of water in atmosphere and maintain the surface temperature at moderate level.

  2. Stochastic volatility and stochastic leverage

    DEFF Research Database (Denmark)

    Veraart, Almut; Veraart, Luitgard A. M.

    This paper proposes the new concept of stochastic leverage in stochastic volatility models. Stochastic leverage refers to a stochastic process which replaces the classical constant correlation parameter between the asset return and the stochastic volatility process. We provide a systematic...... treatment of stochastic leverage and propose to model the stochastic leverage effect explicitly, e.g. by means of a linear transformation of a Jacobi process. Such models are both analytically tractable and allow for a direct economic interpretation. In particular, we propose two new stochastic volatility...... models which allow for a stochastic leverage effect: the generalised Heston model and the generalised Barndorff-Nielsen & Shephard model. We investigate the impact of a stochastic leverage effect in the risk neutral world by focusing on implied volatilities generated by option prices derived from our new...

  3. Potential of derived lunar volatiles for life support

    Science.gov (United States)

    Bula, R. J.; Wittenberg, L. J.; Tibbitts, T. W.; Kulcinski, G. L.

    1992-01-01

    The lunar regolith contains small quantities of solar wind implanted volatile compounds that have vital, basic uses for maintaining life support systems of lunar or space settlements. Recent proposals to utilize the helium-3 isotope (He-3) derived from the lunar regolith as a fuel for fusion reactors would result in the availability of large quantities of other lunar volatile compounds. The quantities obtained would provide the annual life support replacement requirements of 1150 to 23,000 inhabitants per ton of He-3 recovered, depending on the volatile compound. Utilization of the lunar volatile compounds for life support depends on the costs, in terms of materials and energy, associated with their extraction from the lunar regolith as compared to the delivery costs of these compounds from Earth resources. Considering today's conservative estimated transportation costs ($10,000 dollars per kilogram) and regolith mining costs ($5 dollars per ton), the life support replacement requirements could be more economically supplied by recovering the lunar volatile compounds than transporting these materials from Earth resources, even before He-3 will be utilized as a fusion fuel. In addition, availability of lunar volatile compounds could have a significant cost impact on maintaining the life support systems of the space station and a Mars base.

  4. On forecasting Exchange Rate Volatility.

    OpenAIRE

    Hafner, Christian

    2003-01-01

    In an efficient market, foreign exchange rates have to guarantee absence of triangular arbitrage. This note shows that the no-arbitrage condition can be exploited for forecasting the volatility of a single rate by using the information contained in the other rates. Linearly transforming the volatility forecasts of a bivariate model is shown to be more efficient than using a univariate model for the cross-rate.

  5. An alternative method for determining particle-size distribution of forest road aggregate and soil with large-sized particles

    Science.gov (United States)

    Hakjun Rhee; Randy B. Foltz; James L. Fridley; Finn Krogstad; Deborah S. Page-Dumroese

    2014-01-01

    Measurement of particle-size distribution (PSD) of soil with large-sized particles (e.g., 25.4 mm diameter) requires a large sample and numerous particle-size analyses (PSAs). A new method is needed that would reduce time, effort, and cost for PSAs of the soil and aggregate material with large-sized particles. We evaluated a nested method for sampling and PSA by...

  6. Implications of Climate Volatility for Agricultural Commodity Markets in the Presence of Biofuel Mandates

    Science.gov (United States)

    Verma, M.; Diffenbaugh, N. S.; Hertel, T. W.; Beckman, J.

    2011-12-01

    In presence of bio-fuels, link between energy and agricultural commodity markets has become more complex. An increase in ethanol production to minimum 15bn gallons a year - Renewable Fuel Standard (RFS) and current technically permissible maximum 10% blending limit - Blend Wall (BW); make the link even stronger. If oil prices in future do not rise significantly from their current levels, this minimum production requirement would likely be binding. In such a scenario any fluctuation in crop production will have to be absorbed by the non-ethanol usage of the crop and would translate into crop prices adjusting to clear the markets and therefore the commodity prices will be more volatile. At high oil prices it is possible that the BW may become binding, severing the link between oil prices and commodity prices as well, potentially leading to higher price volatility. Hertel and Beckman (2010) find that, with both RFS and BW simultaneously binding, corn price volatility due to supply side shocks (which could arise from extreme climate events) could be more than 50% as large as in the absence of bio-fuel policies. So energy markets are important determinants of agricultural commodity price volatility. This proposal intends to introduce the increased supply side volatility on account of climate change and volatility, in the framework. Global warming on account of increased GHG concentrations is expected to increase the intensity and frequency of hot extremes in US (Diffenbaugh et al. 2008) and therefore affect corn yields. With supply shocks expected to increase, binding RFS and BW will exacerbate the volatility, while if they are non-binding then the price changes could be cushioned. We propose to model the impacts of climate changes and volatility on commodity prices by linking three main components - a. Projections for change in temperature and precipitation using climate model b. A statistical model to predict impacts of change in climate variable on corn yields in US

  7. Neutron Spectrometer Prospecting During the Mojave Volatiles Project Analog Field Test

    Science.gov (United States)

    Elphic, R. C.; Heldmann, J. L.; Colaprete, A.; Hunt, D. R.; Deans, M C.; Lim, D. S.; Foil, G.; Fong, T.

    2015-01-01

    We know there are volatiles sequestered at the poles of the Moon. While we have evidence of water ice and a number of other compounds based on remote sensing, the detailed distribution, and physical and chemical form are largely unknown. Additional orbital studies of lunar polar volatiles may yield further insights, but the most important next step is to use landed assets to fully characterize the volatile composition and distribution at scales of tens to hundreds of meters. To achieve this range of scales, mobility is needed. Because of the proximity of the Moon, near real-time operation of the surface assets is possible, with an associated reduction in risk and cost. This concept of operations is very different from that of rovers on Mars, and new operational approaches are required to carry out such real-time robotic exploration. The Mojave Volatiles Project (MVP) is a Moon- Mars Analog Mission Activities (MMAMA) program effort aimed at (1) determining effective approaches to operating a real-time but short-duration lunar surface robotic mission, and (2) performing prospecting science in a natural setting, as a test of these approaches. We know there are volatiles sequestered at the poles of the Moon. While we have evidence of water ice and a number of other compounds based on remote sensing, the detailed distribution, and physical and chemical form are largely unknown. Additional orbital studies of lunar polar volatiles may yield further insights, but the most important next step is to use landed assets to fully characterize the volatile composition and distribution at scales of tens to hundreds of meters. To achieve this range of scales, mobility is needed. Because of the proximity of the Moon, near real-time operation of the surface assets is possible, with an associated reduction in risk and cost. This concept of operations is very different from that of rovers on Mars, and new operational approaches are required to carry out such robotic exploration. The

  8. Effects of minerals in ferric bauxite on sodium carbonate decomposition and volatilization

    Institute of Scientific and Technical Information of China (English)

    胡文韬; 王化军; 刘欣伟; 孙传尧

    2015-01-01

    Direct reduction is an emerging technology for ferric bauxite utilization. However, because of sodium volatilization, its sodium carbonate consumption is considerably higher than that in ordinary bauxite processing technology. TG-DSC and XRD were applied to detecting phase transformation and mass loss in direct reduction to reveal the mechanism on sodium volatilization. The results show that the most significant influence factor of ferric bauxite on sodium volatilization in direct reduction system is its iron content. Sodium volatilization is probably ascribed to the instability of amorphous substances structure. Amorphous substances are the intermediate-products of the reaction, and the volatilization rate of sodium increases with its generating rate. These amorphous substances are volatile, thus, more sodium is volatilized with its generation. A small amount of amorphous substances are generated in the reaction between Na2CO3and Al2O3; thus, only 3.15% of sodium is volatilized. Similarly, the volatilization rate is 1.87% in the reaction between Na2CO3and SiO2. However, the volatilization rate reaches 7.64% in the reaction between Na2CO3 and Fe2O3 because of the generation of a large amount of amorphous substances.

  9. GC-MS法检测球花石斛花中挥发性成分%Determination of volatile components From flower of Dendrobium thyrsiflorum by GC-MS

    Institute of Scientific and Technical Information of China (English)

    崔娟; 刘圣; 胡江苗

    2013-01-01

    Objective To study the chemical constituents of volatile oil from flower of Dendrobium thyrsiflorum by GC-MS technology. Methods The chemical compositions of volatile oil of the plant were obtained by water reflux method and then analyzed by GC-MS e-quipped. Results About twenty-two compounds were identified with the computer standard spectra as linoleic acid( 51. 82% ),linolenic acid( 10.056% ),palmitic acid( 9. 282% ),stearic acid ( 4. 579% ),8-hydroxy-4,7-dimethyl coumarin( 4. 727% )6,7-dimethoxy cou-marin( 3. 083% ),tricosane( 4. 490% )etc. Conclusions This paper reports,for the first time,the composition of volatile oils of flowers Dendrobium thyrsiflorum by GC-MS.%目的 研究球花石斛花中挥发性的化学成分.方法 采用水回流法从球花石斛花中提取挥发性成分,并用气相色谱-质谱(GC-MS)联用技术,对球花石斛花中的挥发性成分进行了测定.结果 共鉴定出22种化学成分,其中含量较高的主要有亚油酸(51.82%)、亚麻酸(10.056%)、棕榈酸(9.282%)、硬脂酸(4.579%)、8-羟基-4,7-二甲基香豆素(4.727%)、6,7-二甲氧基香豆素(3.083%)、二十三烷(4.490%)等.结论 该文首次采用气相色谱-质谱(GC-MS)联用技术对球花石斛花挥发性成分进行提取研究.

  10. Very long hillslope transport timescales determined from uranium-series isotopes in river sediments from a large, tectonically stable catchment

    Science.gov (United States)

    Suresh, P. O.; Dosseto, A.; Hesse, P. P.; Handley, H. K.

    2014-10-01

    The uranium-series isotopic compositions of soils and sediments evolve in response to time and weathering conditions. Therefore, these isotopes can be used to constrain the timescales of river sediment transport. Catchment evolution depends on the sediment dynamic timescales, on which erosion imparts a major control. Erosion rates in tectonically stable catchments are expected to be lower than those in tectonically active catchments, implying longer sediment residence times in tectonically stable catchments. Mineralogical, elemental and isotopic data are presented for modern channel sediments, alluvial and colluvial deposits from the Murrumbidgee River, a large catchment in the passive margin highlands of south-eastern Australia and three of its tributaries from the headwaters to the alluvial plain. Low variability in Si-based Weathering Index indicates that there is little chemical weathering occurring in the Murrumbidgee River during sediment transport. However, quartz content increases and plagioclase content decreases downstream, indicating progressive mineralogical sorting and/or physical comminution with increasing transport distance. U-series isotopic ratios in the Murrumbidgee River trunk stream sediments show no systematic downstream variation. The weathering ages of sediments within the catchment were determined using a loss-gain model of U-series isotopes. Modern sediments from a headwater tributary, the Bredbo River at Frogs Hollow, have a weathering age of 76 ± 30 kyr but all other modern channel sediments from the length of the Murrumbidgee River and its main tributaries have weathering ages ∼400 ± 180 kyr. The two headwater colluvial deposits have weathering ages of 57 ± 13 and 47 ± 11 kyr, respectively. All the alluvial deposits have weathering ages similar to those of modern sediments. No downstream trend in weathering age is observed. Together with the soil residence time of up to 30 kyr for ridge-top soils at Frogs Hollow in the upper

  11. Magmatic gas flux emissions from Gorelyi volcano, Kamchatka, and implications for volatile recycling in the NW Pacific

    Science.gov (United States)

    Aiuppa, A.; Bagnato, E.; Calabrese, S.; Giudice, G.; Liuzzo, M.; Tamburello, G.; Allard, P.; Chaplygin, I.; Taran, Y.

    2012-04-01

    The Kamchatka peninsula, in the north-western part of the Pacific 'Ring of Fire', is one of the most active volcanic realms on Earth, with 29 historically erupting volcanoes along its ~700 km-long Eastern Volcanic Belt (EVB). This notwithstanding, volatile input and output fluxes along this arc sector have remained poorly characterised until very recently. We here report on the very first assessment of volatile flux emissions from Gorelyi, a large (25 km3, 1830 m high) and most active shield-like Holocene volcano located on the southern segment of the Kamchatka EVB. By combing results from a variety of in situ and remote sensing techniques (MultiGAS, filter packs, and UV camera), we determine the bulk plume molar concentrations of major (H2O 93.5%, CO2 2.6%, SO2 2.2%, HCl 1.1%, HF 0.3%, H2 0.2%) to trace-halogens (Br, I) and trace-element volatile species, and we estimate a total gas release of ~11,000 t/day from Gorelyi during ~900°C non-eruptive degassing. Using this observation, we derive new constraints on the abundances and origins of volatiles in the subduction-modified mantle source feeding magmatism in Kamchatka.

  12. Determination of concentration of radon, volatile organic compounds (VOC) and water chemistry in springs near to Popocatepetl volcano; Determinacion de la concentracion de radon, VOCs y Quimica del agua en manantiales cercanos al volcan Popocatepetl

    Energy Technology Data Exchange (ETDEWEB)

    Pena, P.; Segovia, N.; Lopez M, B.E.; Cisniega, G. [ININ, A.P. 18-1027, 11801 Mexico D.F. (Mexico); Valdes, C.; Armienta, M.A.; Mena, M. [Instituto de Geofisica, UNAM, 04510 Mexico D.F. (Mexico)

    2004-07-01

    Popocatepetl volcano is a high-risk active volcano in Central Mexico where the highest population density in the country is settled. Radon in the soil and groundwater together with water chemistry from samples of nearby springs is analysed as a function of the 2002-2003 volcanic activity. Soil radon indicated fluctuations related both the meteorological parameters and sporadic explosive events. Groundwater radon showed essentially differences in concentration due to the specific characteristics of the studied springs. Water chemistry showed stability along the monitoring period indicating also differences between springs. No anthropogenic pollution from volatile organic compounds was observed. (Author)

  13. Detection of rare species of volatile organic selenium metabolites in male golden hamster urine.

    Science.gov (United States)

    Kwak, Jae; Ohrnberger, Sarah A; Valencak, Teresa G

    2016-07-01

    Selenium has been considered as an essential trace element in mammals and its intake comes mainly from food. Mammals can metabolize both inorganic and organic species, and urinary excretion is the primary elimination route of selenium. Selenosugars and trimethylselenonium ion have been identified as major urinary metabolites. Other metabolites have been reported, but they were detected in some studies and not in others. Still, a large portion of the ingested selenium eliminated from the body is unknown. Volatile selenium species may account for a certain portion of the unknown species since they can easily be lost during sample analyses. While we analyzed male golden hamster urine in search of potential volatile pheromone(s), four volatile selenium compounds were detected. They were dimethyl selenenylsulfide, dimethyl diselenide, dimethyl bis(thio)selenide, and dimethyl selenodisulfide. When the urine samples were aged and dried for 48 h, dimethyl selenodisulfide tended to increase, while others decreased. The increase might be due to the formation of dimethyl selenodisulfide via reaction of dimethyl diselenide and dimethyl trisulfide whose concentration increased as urine aged. To our knowledge, dimethyl bis(thio)selenide and dimethyl selenodisulfide have never been demonstrated in urine. It remains to be determined whether these species are common metabolites in other animals or hamster-specific.

  14. 固相微萃取-气质联用法对红子种子挥发性组分的测定%Determination of Volatile Components from Seeds of Pyracantha fortuneana by SPME-GC-MS

    Institute of Scientific and Technical Information of China (English)

    钟宏波; 陈青; 韦黄山

    2012-01-01

    Volatile components from seed of Pyracantha fortuneana (Maxim.) Ii were extracted by solid phase micro-extraction and analyzed by gas chromatography-mass spectrometry (SPME-GC-MS). 30 compounds in seed were identified, which were 91.98% of total volatile constitutes, such as dodecanoic acid (12.36%), (E,E)-2, 4-decadienal (8.87%), (Z,Z)-9, 12-octadecadienoic acid(7.96%), nonanal(6.91%), hexanal (6.79%), 2-undecenal (5.20%) and so on.%采用固相微萃取法提取贵州红子[Pyracantha fortuneana (Maxim.)Li]种子中的挥发性组分,采用GC-MS进行分析.结果表明,从红子种子中共鉴定出30种化学组分,占挥发性组分的91.98%,包括月桂酸(12.36%)、(E,E)-2,4-癸二烯醛(8.87%)、亚油酸(7.96%)、壬醛(6.91%)、己醛(6.79%)和2-十一烯醛(5.20%)等.

  15. Core-Mantle Partitioning of Volatile Siderophile Elements and the Origin of Volatile Elements in the Earth

    Science.gov (United States)

    Nickodem, K.; Righter, K.; Danielson, L.; Pando, K.; Lee, C.

    2012-01-01

    There are currently several hypotheses on the origin of volatile siderophile elements in the Earth. One hypothesis is that they were added during Earth s accretion and core formation and mobilized into the metallic core [1], others claim multiple stage origin [2], while some hypothesize that volatiles were added after the core already formed [3]. Several volatile siderophile elements are depleted in Earth s mantle relative to the chondrites, something which continues to puzzle many scientists. This depletion is likely due to a combination of volatility and core formation. The Earth s core is composed of Fe and some lighter constituents, although the abundances of these lighter elements are unknown [4]. Si is one of these potential light elements [5] although few studies have analyzed the effect of Si on metal-silicate partitioning, in particular the volatile elements. As, In, Ge, and Sb are trace volatile siderophile elements which are depleted in the mantle but have yet to be extensively studied. The metal-silicate partition coefficients of these elements will be measured to determine the effect of Si. Partition coefficients depend on temperature, pressure, oxygen fugacity, and metal and silicate composition and can constrain the concentrations of volatile, siderophile elements found in the mantle. Reported here are the results from 13 experiments examining the partitioning of As, In, Ge, and Sb between metallic and silicate liquid. These experiments will examine the effect of temperature, and metal-composition (i.e., Si content) on these elements in or-der to gain a greater understanding of the core-mantle separation which occurred during the Earth s early stages. The data can then be applied to the origin of volatile elements in the Earth.

  16. Parametric Portfolio Policies with Common Volatility Dynamics

    DEFF Research Database (Denmark)

    Ergemen, Yunus Emre; Taamouti, Abderrahim

    A parametric portfolio policy function is considered that incorporates common stock volatility dynamics to optimally determine portfolio weights. Reducing dimension of the traditional portfolio selection problem significantly, only a number of policy parameters corresponding to first- and second......-order characteristics are estimated based on a standard method-of-moments technique. The method, allowing for the calculation of portfolio weight and return statistics, is illustrated with an empirical application to 30 U.S. industries to study the economic activity before and after the recent financial crisis....

  17. Spiral mining for lunar volatiles

    Science.gov (United States)

    Schmitt, H. H.; Kulcinski, G. L.; Sviatoslavsky, I. N.; Carrier, W. D., III

    Lunar spiral mining, extending outward from a periodically mobile central power and processing station represents an alternative for comparison with more traditional mining schemes. In this concept, a mining machine would separate regolith fines and extract the contained volatiles. Volatiles then would be pumped along the miner's support arm to the central station for refining and for export or storage. The basic architecture of the central processing station would be cylindrical. A central core area could house the power subsystem of hydrogen-oxygen engines or fuel cells. Habitat sections and other crew occupied areas could be arranged around the power generation core. The outer cylinder could include all volatile refining subsystems. Solar thermal power collectors and reflectors would be positioned on top of the central station. Long term exploitation of a volatile resource region would begin with establishment of a support base at the center of a long boundary of the region. The mining tract for each spiral mining system would extend orthogonal to this boundary. New spiral mining systems would be activated along parallel tracts as demand for lunar He-3 and other solar wind volatiles increased.

  18. Chemical composition of the volatile oil from Zanthoxylum avicennae and antimicrobial activities and cytotoxicity

    Directory of Open Access Journals (Sweden)

    Yin Lin

    2014-01-01

    Full Text Available Background: Through literature retrieval, there has been no report on the research of the chemical components in Zanthoxylum avicennae (Lam. DC. This paper extracted and determined the chemical components of the volatile oil in Z. avicennae, and at the same time, measured and evaluated the bioactivity of the volatile oil in Z. avicennae. Materials and Methods: We extract the volatile oil in Z. avicennae by steam distillation method, determined the chemical composition of the volatile oil by GC-MS coupling technique, and adopt the peak area normalization method to measured the relative percentage of each chemical composition in the volatile oil. Meanwhile, we use the Lethal-to-prawn larva bioactivity experiment to screen the cytotoxicity activities of the volatile oil in Z. avicennae, and using the slanting test-tube experiment to determine and evaluate its antibacterial activities in vitro for the eight kinds of plant pathogenic fungi in the volatile oil of the Z. avicennae. Results: The results show that 68 kinds of compounds are determined from the volatile oil of Z. avicennae. The determined part takes up 97.89% of the total peak area. The main ingredients in the volatile oil of Z. avicennae are sesquiterpenoids and monoterpene. The test results show that the volatile oil in Z. avicennae has strong antibacterial activities and cytotoxicity, with the strongest antibacterial activity against the Rhizoctonia solani AG1-1A. Conclusion: This research results will provide reference data for understanding the chemical composition of the volatile oil in the aromatic plant of Z. avicennae and its bioactivity, and for its further development and application.

  19. Screening of natural organic volatiles from Prunus mahaleb L. honey: coumarin and vomifoliol as nonspecific biomarkers

    National Research Council Canada - National Science Library

    Jerković, Igor; Marijanović, Zvonimir; Staver, Mladenka Malenica

    2011-01-01

    ...) were used for the analysis of Prunus mahaleb L. honey samples. Screening was focused toward chemical composition of natural organic volatiles to determine if it is useful as a method of determining honey-sourcing...

  20. RICE PRICE VOLATILITY IN EAST JAVA

    Directory of Open Access Journals (Sweden)

    Wati R.Y.E.

    2017-09-01

    Full Text Available The purpose of the research is analyzing the volatility and volatility spillover of monthly price of paddy at the level of farmers and consumers in 2010-2016. ARCH/GARCH used to analyze volatility and GARCH BEKK-model is used to analyze the volatility spillover. The results of the analysis show that price volatility at the farmer level is very high (extremely high volatility, price volatility at the consumer level is low (low volatility, and volatility spillover does not occur between the farmers and the consumers market. The need to guarantee an effective floor price as well as information disclosure related to the market commodity prices so that the pattern of prices transmission among interrelated markets can be symmetrical.

  1. The price of fixed income market volatility

    CERN Document Server

    Mele, Antonio

    2015-01-01

    Fixed income volatility and equity volatility evolve heterogeneously over time, co-moving disproportionately during periods of global imbalances and each reacting to events of different nature. While the methodology for options-based "model-free" pricing of equity volatility has been known for some time, little is known about analogous methodologies for pricing various fixed income volatilities. This book fills this gap and provides a unified evaluation framework of fixed income volatility while dealing with disparate markets such as interest-rate swaps, government bonds, time-deposits and credit. It develops model-free, forward looking indexes of fixed-income volatility that match different quoting conventions across various markets, and uncovers subtle yet important pitfalls arising from naïve superimpositions of the standard equity volatility methodology when pricing various fixed income volatilities. The ultimate goal of the authors´ efforts is to make interest rate volatility standardization a valuable...

  2. Real-Time and Delayed Analysis of Tree and Shrub Cores as Indicators of Subsurface Volatile Organic Compound Contamination, Durham Meadows Superfund Site, Durham, Connecticut, August 29, 2006

    Science.gov (United States)

    Vroblesky, Don A.; Willey, Richard E.; Clifford, Scott; Murphy, James J.

    2008-01-01

    trichloroethene) may be attributable to the relatively large depth to water (17.6 feet), the relatively low soil-vapor trichloroethene concentration, and the large amount of rainfall during and preceding the tree-coring event. The data indicate that real-time and delayed analyses of tree cores are viable approaches to examining subsurface volatile organic compound soil-gas or vadose-zone contamination at the Durham Meadows Superfund Site and other similar sites. Thus, the methods may have application for determining the potential for vapor intrusion into buildings.

  3. The emission of volatile compounds from leaf litter

    NARCIS (Netherlands)

    Derendorp, L.

    2012-01-01

    Leaf litter is available at the Earth’s surface in large quantities. During the decomposition of leaf litter, volatile compounds can be released into the atmosphere, where they potentially influence local air quality, atmospheric chemistry or the global climate. In this thesis the focus was on the e

  4. The emission of volatile compounds from leaf litter

    NARCIS (Netherlands)

    Derendorp, L.|info:eu-repo/dai/nl/314016414

    2012-01-01

    Leaf litter is available at the Earth’s surface in large quantities. During the decomposition of leaf litter, volatile compounds can be released into the atmosphere, where they potentially influence local air quality, atmospheric chemistry or the global climate. In this thesis the focus was on the

  5. Isolation and quantification of volatiles in fish by dynamic headspace sampling and mass spectrometry

    DEFF Research Database (Denmark)

    Refsgaard, Hanne; Haahr, Anne-Mette; Jensen, Benny

    1999-01-01

    determined by use of this sample preparation method and for samples chewed for 10 s. Effects of sampling time, temperature, and purge flow on level of volatiles were tested. Purging at 340 mL/min for 30 min at 45 degrees C was found to be optimal. Detection Emits for a number of aldehydes were 0.2-2.7 mu g......A dynamic headspace sampling method for isolation of volatiles in fish has been developed. The sample preparation involved freezing of fish tissue in liquid nitrogen, pulverizing the tissue, and sampling of volatiles from an aqueous slurry of the fish powder. Similar volatile patterns were...

  6. Mapping the release of volatiles in the inner comae of comets C/2012 F6 (Lemmon) and C/2012 S1 (ISON) using the Atacama Large Millimeter/Submillimeter Array

    CERN Document Server

    Cordiner, M A; Boissier, J; Milam, S N; Mumma, M J; Charnley, S B; Paganini, L; Villanueva, G; Bockelee-Morvan, D; Kuan, Y -J; Chuang, Y -L; Lis, D C; Biver, N; Crovisier, J; Minniti, D; Coulson, I M

    2014-01-01

    Results are presented from the first cometary observations using the Atacama Large Millimeter/Submillimeter Array (ALMA), including measurements of the spatially-resolved distributions of HCN, HNC, H$_2$CO and dust within the comae of two comets: C/2012 F6 (Lemmon) and C/2012 S1 (ISON), observed at heliocentric distances of 1.5 AU and 0.54 AU, respectively. These observations (with angular resolution $\\approx0.5''$), reveal an unprecedented level of detail in the distributions of these fundamental cometary molecules, and demonstrate the power of ALMA for quantitative measurements of the distributions of molecules and dust in the inner comae of typical bright comets. In both comets, HCN is found to originate from (or within a few hundred km of) the nucleus, with a spatial distribution largely consistent with spherically-symmetric, uniform outflow. By contrast, the HNC distributions are clumpy and asymmetrical, with peaks at cometocentric radii $\\sim$500-1000~km, consistent with release of HNC in collimated out...

  7. Modeling the Implied Volatility Surface-: A Study for S&P 500 Index Option

    Directory of Open Access Journals (Sweden)

    Jin Zheng

    2013-02-01

    Full Text Available The aim of this study is to demonstrate a framework to model the implied volatilities of S&P 500 index options and estimate the implied volatilities of stock prices using stochastic processes. In this paper, three models are established to estimate whether the implied volatilities are constant during the whole life of options. We mainly concentrate on the Black-Scholes and Dumas’ option models and make the empirical comparisons. By observing the daily-recorded data of S&P 500 index, we study the volatility model and volatility surface. Results from numerical experiments show that the stochastic volatilities are determined by moneyness rather than constant. Our research is of vital importance, especially for forecasting stock market shocks and crises, as one of the applications.

  8. Rheology of Volatile-rich Crystal Mush

    Science.gov (United States)

    Pistone, M.; Caricchi, L.; Ulmer, P.; Reusser, E.; Mancktelow, N.; Burlini, L.

    2012-04-01

    becomes dominant. Comparing our results with previous ones for the rheology of crystal-bearing systems (Caricchi et al., 2007), the presence of limited amount of gas bubbles (12 vol% maximum) favors an evident decrease in viscosity; e.g., at about 70 vol% crystals a decrease of about 4 orders of magnitude in relative viscosity is caused by adding only 9 vol% bubbles. These experiments suggest that magma rheology is strongly controlled by the simultaneous presence of bubbles and crystals in the melt phase and their interactions during deformation. The localization in strain favors granite mobilization in the crust and the occurrence of large-scale eruptions; in contrast, the crystal interlocking halts the batholith in the crust and determines its viscous death.

  9. Involvement of a volatile metabolite during phosphoramide mustard-induced ovotoxicity

    Energy Technology Data Exchange (ETDEWEB)

    Madden, Jill A. [Department of Animal Science, Iowa State University, Ames, IA 50011 (United States); Hoyer, Patricia B. [Department of Physiology, University of Arizona, Tucson, AZ 85724 (United States); Devine, Patrick J. [INRS—Institut Armand-Frappier Research Centre, University of Quebec, Laval, QC H7V 1B7 (Canada); Keating, Aileen F., E-mail: akeating@iastate.edu [Department of Animal Science, Iowa State University, Ames, IA 50011 (United States); Department of Physiology, University of Arizona, Tucson, AZ 85724 (United States)

    2014-05-15

    The finite ovarian follicle reserve can be negatively impacted by exposure to chemicals including the anti-neoplastic agent, cyclophosphamide (CPA). CPA requires bioactivation to phosphoramide mustard (PM) to elicit its therapeutic effects however; in addition to being the tumor-targeting metabolite, PM is also ovotoxic. In addition, PM can break down to a cytotoxic, volatile metabolite, chloroethylaziridine (CEZ). The aim of this study was initially to characterize PM-induced ovotoxicity in growing follicles. Using PND4 Fisher 344 rats, ovaries were cultured for 4 days before being exposed once to PM (10 or 30 μM). Following eight additional days in culture, relative to control (1% DMSO), PM had no impact on primordial, small primary or large primary follicle number, but both PM concentrations induced secondary follicle depletion (P < 0.05). Interestingly, a reduction in follicle number in the control-treated ovaries was observed. Thus, the involvement of a volatile, cytotoxic PM metabolite (VC) in PM-induced ovotoxicity was explored in cultured rat ovaries, with control ovaries physically separated from PM-treated ovaries during culture. Direct PM (60 μM) exposure destroyed all stage follicles after 4 days (P < 0.05). VC from nearby wells depleted primordial follicles after 4 days (P < 0.05), temporarily reduced secondary follicle number after 2 days, and did not impact other stage follicles at any other time point. VC was determined to spontaneously liberate from PM, which could contribute to degradation of PM during storage. Taken together, this study demonstrates that PM and VC are ovotoxicants, with different follicular targets, and that the VC may be a major player during PM-induced ovotoxicity observed in cancer survivors. - Highlights: • PM depletes all stage ovarian follicles in a temporal pattern. • A volatile ovotoxic compound is liberated from PM. • The volatile metabolite depletes primordial follicles.

  10. Observability of market daily volatility

    Science.gov (United States)

    Petroni, Filippo; Serva, Maurizio

    2016-02-01

    We study the price dynamics of 65 stocks from the Dow Jones Composite Average from 1973 to 2014. We show that it is possible to define a Daily Market Volatility σ(t) which is directly observable from data. This quantity is usually indirectly defined by r(t) = σ(t) ω(t) where the r(t) are the daily returns of the market index and the ω(t) are i.i.d. random variables with vanishing average and unitary variance. The relation r(t) = σ(t) ω(t) alone is unable to give an operative definition of the index volatility, which remains unobservable. On the contrary, we show that using the whole information available in the market, the index volatility can be operatively defined and detected.

  11. Consistent ranking of volatility models

    DEFF Research Database (Denmark)

    Hansen, Peter Reinhard; Lunde, Asger

    2006-01-01

    result in an inferior model being chosen as "best" with a probability that converges to one as the sample size increases. We document the practical relevance of this problem in an empirical application and by simulation experiments. Our results provide an additional argument for using the realized...... variance in out-of-sample evaluations rather than the squared return. We derive the theoretical results in a general framework that is not specific to the comparison of volatility models. Similar problems can arise in comparisons of forecasting models whenever the predicted variable is a latent variable.......We show that the empirical ranking of volatility models can be inconsistent for the true ranking if the evaluation is based on a proxy for the population measure of volatility. For example, the substitution of a squared return for the conditional variance in the evaluation of ARCH-type models can...

  12. The volatile compound BinBase mass spectral database

    Directory of Open Access Journals (Sweden)

    Barupal Dinesh K

    2011-08-01

    ://vocbinbase.fiehnlab.ucdavis.edu. Conclusions The BinBase database algorithms have been successfully modified to allow for tracking and identification of volatile compounds in complex mixtures. The database is capable of annotating large datasets (hundreds to thousands of samples and is well-suited for between-study comparisons such as chemotaxonomy investigations. This novel volatile compound database tool is applicable to research fields spanning chemical ecology to human health. The BinBase source code is freely available at http://binbase.sourceforge.net/ under the LGPL 2.0 license agreement.

  13. Oil Volatility Risk and Expected Stock Returns

    DEFF Research Database (Denmark)

    Christoffersen, Peter; Pan, Xuhui (Nick)

    After the financialization of commodity futures markets in 2004-05 oil volatility has become a strong predictor of returns and volatility of the overall stock market. Furthermore, stocks' exposure to oil volatility risk now drives the cross-section of expected returns. The difference in average...... return between the quintile of stocks with low exposure and high exposure to oil volatility is significant at 0.66% per month, and oil volatility risk carries a significant risk premium of -0.60% per month. In the post-financialization period, oil volatility risk is strongly related with various measures...

  14. Factors That Determine the Career Stability of Assistant Principals in a Large Urban School District in the Southeast

    Science.gov (United States)

    Edwards, Danielle Felder

    2009-01-01

    This study examined the career stability (career choices assistant principals intend to make over the next five to ten years) in a large, urban school district in the southeastern region of the United States in order to identify factors significantly related to their career aspirations. The study invited a purposive sample (n = 177) of assistant…

  15. 77 FR 9204 - Large Power Transformers From the Republic of Korea: Preliminary Determination of Sales at Less...

    Science.gov (United States)

    2012-02-16

    ... injury, by reason of imports from Korea of large power transformers.\\6\\ \\6\\ See 76 FR 54790 (September 2... Korea: Initiation of Antidumping Duty Investigation, 76 FR 49439 (August 10, 2011) (Initiation Notice). \\2\\ See Initiation Notice, 76 FR at 49440; see also Antidumping Duties; Countervailing Duties,...

  16. Rhenium volatilization in waste glasses

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Kai; Pierce, David A. [Pacific Northwest National Laboratory, Richland, WA 99352 (United States); Hrma, Pavel, E-mail: pavel.hrma@pnnl.gov [Pacific Northwest National Laboratory, Richland, WA 99352 (United States); Schweiger, Michael J. [Pacific Northwest National Laboratory, Richland, WA 99352 (United States); Kruger, Albert A. [U.S. Department of Energy, Office of River Protection, Richland, WA 99352 (United States)

    2015-09-15

    Highlights: • Re did not volatilize from a HLW feed until 1000 °C. • Re began to volatilize from LAW feeds at ∼600 °C. • The vigorous foaming and generation of gases from salts enhanced Re evaporation in LAW feeds. • The HLW glass with less foaming and salts is a promising medium for Tc immobilization. - Abstract: We investigated volatilization of rhenium (Re), sulfur, cesium, and iodine during the course of conversion of high-level waste melter feed to glass and compared the results for Re volatilization with those in low-activity waste borosilicate glasses. Whereas Re did not volatilize from high-level waste feed heated at 5 K min{sup −1} until 1000 °C, it began to volatilize from low-activity waste borosilicate glass feeds at ∼600 °C, a temperature ∼200 °C below the onset temperature of evaporation from pure KReO{sub 4}. Below 800 °C, perrhenate evaporation in low-activity waste melter feeds was enhanced by vigorous foaming and generation of gases from molten salts as they reacted with the glass-forming constituents. At high temperatures, when the glass-forming phase was consolidated, perrhenates were transported to the top surface of glass melt in bubbles, typically together with sulfates and halides. Based on the results of this study (to be considered preliminary at this stage), the high-level waste glass with less foaming and salts appears a promising medium for technetium immobilization.

  17. MAPPING THE RELEASE OF VOLATILES IN THE INNER COMAE OF COMETS C/2012 F6 (LEMMON) AND C/2012 S1 (ISON) USING THE ATACAMA LARGE MILLIMETER/SUBMILLIMETER ARRAY

    Energy Technology Data Exchange (ETDEWEB)

    Cordiner, M. A.; Milam, S. N.; Mumma, M. J.; Charnley, S. B.; Paganini, L.; Villanueva, G. [Goddard Center for Astrobiology, NASA Goddard Space Flight Center, 8800 Greenbelt Road, Greenbelt, MD 20771 (United States); Remijan, A. J. [National Radio Astronomy Observatory, Charlottesville, VA 22903 (United States); Boissier, J. [IRAM, 300 Rue de la Piscine, F-38406 Saint Martin d' Heres (France); Bockelée-Morvan, D.; Biver, N.; Crovisier, J. [LEISA, Observatoire de Paris, CNRS, UPMC, Université Paris-Diderot, 5 Place Jules Janssen, F-92195 Meudon (France); Kuan, Y.-J.; Chuang, Y.-L. [National Taiwan Normal University, Taipei 116, Taiwan (China); Lis, D. C. [Sorbonne Universités, Université Pierre et Marie Curie, Paris 6, CNRS, Observatoire de Paris, UMR 8112, LERMA, F-75014 Paris (France); Minniti, D. [Pontifica Universidad Catolica de Chile, Santiago (Chile); Coulson, I. M., E-mail: martin.cordiner@nasa.gov [Joint Astronomy Centre, Hilo, HI 96720 (United States)

    2014-09-01

    Results are presented from the first cometary observations using the Atacama Large Millimeter/Submillimeter Array (ALMA), including measurements of the spatially resolved distributions of HCN, HNC, H{sub 2}CO, and dust within the comae of two comets: C/2012 F6 (Lemmon) and C/2012 S1 (ISON), observed at heliocentric distances of 1.5 AU and 0.54 AU, respectively. These observations (with angular resolution ≈0.''5), reveal an unprecedented level of detail in the distributions of these fundamental cometary molecules, and demonstrate the power of ALMA for quantitative measurements of the distributions of molecules and dust in the inner comae of typical bright comets. In both comets, HCN is found to originate from (or within a few hundred kilometers of) the nucleus, with a spatial distribution largely consistent with spherically symmetric, uniform outflow. By contrast, the HNC distributions are clumpy and asymmetrical, with peaks at cometocentric radii ∼500-1000 km, consistent with release of HNC in collimated outflow(s). Compared to HCN, the H{sub 2}CO distribution in comet Lemmon is very extended. The interferometric visibility amplitudes are consistent with coma production of H{sub 2}CO and HNC from unidentified precursor material(s) in both comets. Adopting a Haser model, the H{sub 2}CO parent scale length is found to be a few thousand kilometers in Lemmon and only a few hundred kilometers in ISON, consistent with the destruction of the precursor by photolysis or thermal degradation at a rate that scales in proportion to the solar radiation flux.

  18. Determining

    Directory of Open Access Journals (Sweden)

    Bahram Andarzian

    2015-06-01

    Full Text Available Wheat production in the south of Khuzestan, Iran is constrained by heat stress for late sowing dates. For optimization of yield, sowing at the appropriate time to fit the cultivar maturity length and growing season is critical. Crop models could be used to determine optimum sowing window for a locality. The objectives of this study were to evaluate the Cropping System Model (CSM-CERES-Wheat for its ability to simulate growth, development, grain yield of wheat in the tropical regions of Iran, and to study the impact of different sowing dates on wheat performance. The genetic coefficients of cultivar Chamran were calibrated for the CSM-CERES-Wheat model and crop model performance was evaluated with experimental data. Wheat cultivar Chamran was sown on different dates, ranging from 5 November to 9 January during 5 years of field experiments that were conducted in the Khuzestan province, Iran, under full and deficit irrigation conditions. The model was run for 8 sowing dates starting on 25 October and repeated every 10 days until 5 January using long-term historical weather data from the Ahvaz, Behbehan, Dezful and Izeh locations. The seasonal analysis program of DSSAT was used to determine the optimum sowing window for different locations as well. Evaluation with the experimental data showed that performance of the model was reasonable as indicated by fairly accurate simulation of crop phenology, biomass accumulation and grain yield against measured data. The normalized RMSE were 3%, 2%, 11.8%, and 3.4% for anthesis date, maturity date, grain yield and biomass, respectively. Optimum sowing window was different among locations. It was opened and closed on 5 November and 5 December for Ahvaz; 5 November and 15 December for Behbehan and Dezful;and 1 November and 15 December for Izeh, respectively. CERES-Wheat model could be used as a tool to evaluate the effect of sowing date on wheat performance in Khuzestan conditions. Further model evaluations

  19. Using electromagnetic induction technology to predict volatile fatty acid, source area differences

    Science.gov (United States)

    Subsurface sampling techniques have been adapted to measure manure accumulation on feedlot surface. Objectives of this study were to determine if sensor data could be used to predict differences in volatile fatty acids (VFA) and other volatiles produced on the feedlot surface three days following a...

  20. 75 FR 82363 - Approval and Promulgation of Implementation Plans; Ohio; Volatile Organic Compound Emission...

    Science.gov (United States)

    2010-12-30

    ... AGENCY 40 CFR Part 52 Approval and Promulgation of Implementation Plans; Ohio; Volatile Organic Compound... printing volatile organic compound (VOC) rule for approval into the Ohio State Implementation Plan (SIP... mercury at 20 degrees Celsius. This rule also contains the appropriate test methods ] for determining...

  1. Indoor volatiles of primary school classrooms in Tapachula, Chiapas, Mexico, are attractants to Aedes aegypti females

    NARCIS (Netherlands)

    Estrada, J.L.T.; Delgado, S.M.R.; Takken, W.

    2013-01-01

    We determined the behavioral response of Aedes aegypti females to volatile compounds collected in indoor primary school classrooms. Volatiles were collected from classrooms from 0800 through 1030 h and 1130 through 1400 h in urban and rural schools in Tapachula, Chiapas, Mexico. Female responses to

  2. Volatile compound profiling of Turkish Divle Cave cheese during production and ripening

    NARCIS (Netherlands)

    Ozturkoglu-Budak, S; Gursoy, A; Aykas, D P; Koçak, C; Dönmez, S; de Vries, R P; Bron, P A

    2016-01-01

    The formation of volatile compounds in Turkish Divle Cave cheese produced in 3 different dairy farms was determined during production and ripening, revealing 110 compounds including acids, alcohols, ketones, esters, and terpenes. The presence and concentration of these volatile compounds varied betw

  3. Indoor volatiles of primary school classrooms in Tapachula, Chiapas, Mexico, are attractants to Aedes aegypti females

    NARCIS (Netherlands)

    Estrada, J.L.T.; Delgado, S.M.R.; Takken, W.

    2013-01-01

    We determined the behavioral response of Aedes aegypti females to volatile compounds collected in indoor primary school classrooms. Volatiles were collected from classrooms from 0800 through 1030 h and 1130 through 1400 h in urban and rural schools in Tapachula, Chiapas, Mexico. Female responses to

  4. Maternal weight determines the association between Hbalc in second half of pregnancy and risk of large for gestational age babies

    DEFF Research Database (Denmark)

    Nielsen, Gunnar Lauge; Dethlefsen, Claus; Møller, Margrethe

    Aim: To assess the association between maternal glycosylated haemoglobin (HbA1c) in diabetic pregnancies and the risk of delivering large for gestational age babies (LGA) taking into account maternal body mass index (BMI), weight gain, age, White class, and smoking habits.  Method: We identified...... on maternal BMI disclosed that the association was restricted to pregnancies with a pre-pregnancy BMI >23 kg/m2 below that we found no association.  Conclusion: The association between glycosylated haemoglobin and birth of a LGA baby seems to be restricted to women with BMI >23 kg/m2....... all pregnant diabetic women in a Danish county. HbA1c values after 20th gestational week were collected and offspring was categorized as large, normal or small for gestational age. Logistic regression models we fitted to assess the association between HbA1c and risk of delivering a LGA baby taking...

  5. A GIS-assisted regional screening tool to evaluate the leaching potential of volatile and non-volatile pesticides

    Science.gov (United States)

    Ki, Seo Jin; Ray, Chittaranjan

    2015-03-01

    A regional screening tool-which is useful in cases where few site-specific parameters are available for complex vadose zone models-assesses the leaching potential of pollutants to groundwater over large areas. In this study, the previous pesticide leaching tool used in Hawaii was revised to account for the release of new volatile organic compounds (VOCs) from the soil surface. The tool was modified to introduce expanded terms in the traditional pesticide ranking indices (i.e., retardation and attenuation factors), allowing the estimation of the leaching fraction of volatile chemicals based on recharge, soil, and chemical properties to be updated. Results showed that the previous tool significantly overestimated the mass fraction of VOCs leached through soils as the recharge rates increased above 0.001801 m/d. In contrast, the revised tool successfully delineated vulnerable areas to the selected VOCs based on two reference chemicals, a known leacher and non-leacher, which were determined in local conditions. The sensitivity analysis with the Latin-Hypercube-One-factor-At-a-Time method revealed that the new leaching tool was most sensitive to changes in the soil organic carbon sorption coefficient, fractional organic carbon content, and Henry's law constant; and least sensitive to parameters such as the bulk density, water content at field capacity, and particle density in soils. When the revised tool was compared to the analytical (STANMOD) and numerical (HYDRUS-1D) models as a susceptibility measure, it ranked particular VOCs well (e.g., benzene, carbofuran, and toluene) that were consistent with other two models under the given conditions. Therefore, the new leaching tool can be widely used to address intrinsic groundwater vulnerability to contamination of pesticides and VOCs, along with the DRASTIC method or similar Tier 1 models such as SCI-GROW and WIN-PST.

  6. A Consistent Pricing Model for Index Options and Volatility Derivatives

    DEFF Research Database (Denmark)

    Cont, Rama; Kokholm, Thomas

    options on the underlying asset. The model has the convenient feature of decoupling the vanilla skews from spot/volatility correlations and allowing for different conditional correlations in large and small spot/volatility moves. We show that our model can simultaneously fit prices of European options......We propose and study a flexible modeling framework for the joint dynamics of an index and a set of forward variance swap rates written on this index, allowing options on forward variance swaps and options on the underlying index to be priced consistently. Our model reproduces various empirically...... on S&P 500 across strikes and maturities as well as options on the VIX volatility index. The calibration of the model is done in two steps, first by matching VIX option prices and then by matching prices of options on the underlying....

  7. A Consistent Pricing Model for Index Options and Volatility Derivatives

    DEFF Research Database (Denmark)

    Kokholm, Thomas

    on the underlying asset. The model has the convenient feature of decoupling the vanilla skews from spot/volatility correlations and allowing for different conditional correlations in large and small spot/volatility moves. We show that our model can simultaneously fit prices of European options on S&P 500 across......We propose and study a flexible modeling framework for the joint dynamics of an index and a set of forward variance swap rates written on this index, allowing options on forward variance swaps and options on the underlying index to be priced consistently. Our model reproduces various empirically...... strikes and maturities as well as options on the VIX volatility index. The calibration of the model is done in two steps, first by matching VIX option prices and then by matching prices of options on the underlying....

  8. Modeling the influence of precursor volatility and molecular structure on secondary organic aerosol formation using evaporated fuel experiments

    Directory of Open Access Journals (Sweden)

    S. H. Jathar

    2013-09-01

    Full Text Available We use SOA production data from an ensemble of evaporated fuels to test various SOA formation models. Except for gasoline, traditional SOA models focusing exclusively on volatile species in the fuels under-predict the observed SOA formation. These models can be improved dramatically by accounting for lower volatility species, but at the cost of a large set of free parameters. In contrast, a SOA model based only on the volatility of the precursor, starting with the volatility distribution of the evaporated fuels and optimized for the volatility reduction of first-generation products, reasonably reproduces the observed SOA formation with relatively few free parameters. The exceptions are exotic fuels such as Fischer-Tropsch fuels that expose the central assumption of the volatility based model that most emissions consist of complex mixtures displaying reasonably average behavior. However, for the vast majority of fuels, the volatility based model performs well.

  9. Analysis of Large Seeds from Three Different Medicago truncatula Ecotypes Reveals a Potential Role of Hormonal Balance in Final Size Determination of Legume Grains

    Directory of Open Access Journals (Sweden)

    Kaustav Bandyopadhyay

    2016-09-01

    Full Text Available Legume seeds are important as protein and oil source for human diet. Understanding how their final seed size is determined is crucial to improve crop yield. In this study, we analyzed seed development of three accessions of the model legume, Medicago truncatula, displaying contrasted seed size. By comparing two large seed accessions to the reference accession A17, we described mechanisms associated with large seed size determination and potential factors modulating the final seed size. We observed that early events during embryogenesis had a major impact on final seed size and a delayed heart stage embryo development resulted to large seeds. We also observed that the difference in seed growth rate was mainly due to a difference in embryo cell number, implicating a role of cell division rate. Large seed accessions could be explained by an extended period of cell division due to a longer embryogenesis phase. According to our observations and recent reports, we observed that auxin (IAA and abscisic acid (ABA ratio could be a key determinant of cell division regulation at the end of embryogenesis. Overall, our study highlights that timing of events occurring during early seed development play decisive role for final seed size determination.

  10. MYC translocation partner gene determines survival of patients with large B-cell lymphoma with MYC- or double-hit MYC/BCL2 translocations

    DEFF Research Database (Denmark)

    Pedersen, Mette Ø; Gang, Anne O; Poulsen, Tim S;

    2014-01-01

    In large B-cell lymphoma (LBCL) MYC- and MYC/BCL2 double-hit (DH) translocations have been associated with inferior survival. We hypothesised that the negative prognostic impact of MYC translocation was determined by an immunoglobulin MYC translocation partner gene (IG-MYC), as opposed to a non-i...

  11. Determinants of absenteeism in public organizations: A unit-level analysis of work absence in a large Danish municipality

    DEFF Research Database (Denmark)

    Løkke Nielsen, Ann-Kristina

    2008-01-01

    This study investigates the determinants of absenteeism in a large Danish municipality. Based on a review of the literature on absence, an integrative model is developed combining the individual, the social psychological and the economic approaches. The model is tested on data from approximately ...

  12. Analysis of Large Seeds from Three Different Medicago truncatula Ecotypes Reveals a Potential Role of Hormonal Balance in Final Size Determination of Legume Grains

    Science.gov (United States)

    Bandyopadhyay, Kaustav; Uluçay, Orhan; Şakiroğlu, Muhammet; Udvardi, Michael K.; Verdier, Jerome

    2016-01-01

    Legume seeds are important as protein and oil source for human diet. Understanding how their final seed size is determined is crucial to improve crop yield. In this study, we analyzed seed development of three accessions of the model legume, Medicago truncatula, displaying contrasted seed size. By comparing two large seed accessions to the reference accession A17, we described mechanisms associated with large seed size determination and potential factors modulating the final seed size. We observed that early events during embryogenesis had a major impact on final seed size and a delayed heart stage embryo development resulted to large seeds. We also observed that the difference in seed growth rate was mainly due to a difference in embryo cell number, implicating a role of cell division rate. Large seed accessions could be explained by an extended period of cell division due to a longer embryogenesis phase. According to our observations and recent reports, we observed that auxin (IAA) and abscisic acid (ABA) ratio could be a key determinant of cell division regulation at the end of embryogenesis. Overall, our study highlights that timing of events occurring during early seed development play decisive role for final seed size determination. PMID:27618017

  13. Size-dependence of volatile and semi-volatile organic carbon content in phytoplankton cells

    Directory of Open Access Journals (Sweden)

    Sergio eRuiz-Halpern

    2014-07-01

    Full Text Available The content of volatile and semivolatile organic compounds (VOC and SOC, measured as exchangeable dissolved organic carbon (EDOC, was quantified in 9 phytoplanktonic species that spanned 4 orders of magnitude in cell volume, by disrupting the cells and quantifying the gaseous organic carbon released. EDOC content varied 4 orders of magnitude, from 0.0015 to 14.12 pg C cell-1 in the species studied and increased linearly with increasing phytoplankton cell volume following the equation EDOC (pg C cell-1 = -2.35 x cellular volume (CV, µm3 cell-1 0.90 (± 0.3, with a slope (0.90 not different from 1 indicating a constant increase in volatile carbon as the cell size of phytoplankton increased. The percentage of EDOC relative to total cellular carbon was small but varied 20 fold from 0.28 % to 5.17 %, and no obvious taxonomic pattern in the content of EDOC was appreciable for the species tested. The cell release rate of EDOC is small compared to the amount of carbon in the cell and difficult to capture. Nonetheless, the results point to a potential flux of volatile and semivolatile phytoplankton-derived organic carbon to the atmosphere that has been largely underestimated and deserves further attention in the future.

  14. 77 FR 40857 - Large Power Transformers From the Republic of Korea: Final Determination of Sales at Less Than...

    Science.gov (United States)

    2012-07-11

    ... Sales at Less Than Fair Value AGENCY: Import Administration, International Trade Administration... United States at less than fair value (LTFV), as provided in section 735 of the Tariff Act of 1930, as... Transformers From the Republic of Korea: Preliminary Determination of Sales at Less Than Fair Value...

  15. Gas Chromatography-mass Spectrometry Coupled with Solid-phase Microextraction for Determination of Volatile Constituents of Chinese Ginger%固相微萃取-气相色谱/质谱分析生姜的挥发性成分

    Institute of Scientific and Technical Information of China (English)

    宋国新; 邓春晖; 吴丹; 胡耀铭

    2003-01-01

    采用固相微萃取(SPME)技术结合气相色谱-质谱(GC-MS)分析了生姜中的挥发性化合物.用膜厚为100 μm的聚二甲基硅氧烷纤维头萃取新鲜生姜中的挥发性化合物,纤维头在温度为250 ℃气化室进样口脱附3 min.通过顶空SPME-GC-MS方法从生姜中共分离和鉴定出36个化合物.其中主要的化合物为α-水芹烯,莰烯,里哪醇,香叶醛,姜烯,倍半水芹烯,橙花醛,α-没药烯,α-姜黄烯,由色谱峰的峰面积比例计算出各个化合物的相对含量. 研究和讨论了影响SPME条件的参数,包括吸附时间、温度、脱附时间等.%Gas chromatography-mass spectrometry combined with solid-phase microextraction (SPME-GC-MS) was developed for the determination of volatile compounds of ginger. The volatile constituents of fresh ginger were extracted by SPME with a 100 μm polydimethylsiloxane fiber. The fibers were desorbed in a GC injection liner at 250 ℃ for 3 min. With headspace SPME-GC-MS analysis, thirty-six peaks in ginger were separated and identified by mass spectrometry. The volatile compounds included α-phellandrene, camphene, linalool, geranial, zingiberene, sesquiphellandrene, neral, α-bisabolene, α-curcumene etc and their relative contents were calculated on basis of peak area ratio. SPME extraction conditions including time, temperature and desorption time were investigated.

  16. Modeling the Volatility in Global Fertilizer Prices

    NARCIS (Netherlands)

    P-Y. Chen (Ping-Yu); C-L. Chang (Chia-Lin); C-C. Chen (Chi-Chung); M.J. McAleer (Michael)

    2010-01-01

    textabstractThe main purpose of this paper is to estimate the volatility in global fertilizer prices. The endogenous structural breakpoint unit root test and alternative volatility models, including the generalized autoregressive conditional heteroskedasticity (GARCH) model, Exponential GARCH (EGARC

  17. Fluctuation behaviors of financial return volatility duration

    Science.gov (United States)

    Niu, Hongli; Wang, Jun; Lu, Yunfan

    2016-04-01

    It is of significantly crucial to understand the return volatility of financial markets because it helps to quantify the investment risk, optimize the portfolio, and provide a key input of option pricing models. The characteristics of isolated high volatility events above certain threshold in price fluctuations and the distributions of return intervals between these events arouse great interest in financial research. In the present work, we introduce a new concept of daily return volatility duration, which is defined as the shortest passage time when the future volatility intensity is above or below the current volatility intensity (without predefining a threshold). The statistical properties of the daily return volatility durations for seven representative stock indices from the world financial markets are investigated. Some useful and interesting empirical results of these volatility duration series about the probability distributions, memory effects and multifractal properties are obtained. These results also show that the proposed stock volatility series analysis is a meaningful and beneficial trial.

  18. A Fractionally Integrated Wishart Stochastic Volatility Model

    NARCIS (Netherlands)

    M. Asai (Manabu); M.J. McAleer (Michael)

    2013-01-01

    textabstractThere has recently been growing interest in modeling and estimating alternative continuous time multivariate stochastic volatility models. We propose a continuous time fractionally integrated Wishart stochastic volatility (FIWSV) process. We derive the conditional Laplace transform of

  19. Stochastic Volatility and DSGE Models

    DEFF Research Database (Denmark)

    Andreasen, Martin Møller

    This paper argues that a specification of stochastic volatility commonly used to analyze the Great Moderation in DSGE models may not be appropriate, because the level of a process with this specification does not have conditional or unconditional moments. This is unfortunate because agents may...

  20. Determinants of job stress and job satisfaction among supervisory and non-supervisory employees in a large Canadian teaching hospital.

    Science.gov (United States)

    Brown, J A; Woodward, C A; Shannon, H S; Cunningham, C E; Lendrum, B; McIntosh, J; Rosenbloom, D

    1999-01-01

    This article explores the extent to which hospital workers at a large teaching hospital at different managerial/supervisory levels (designated and non-designated supervisors, and non-supervisory staff), experienced job stress and job satisfaction prior to the re-engineering of hospital services. For all groups, increased levels of job demands were associated with higher levels of stress. Lower levels of decision latitude were associated with increased job stress for designated supervisors. Increasing levels of decision latitude were associated with both job stress and satisfaction for the other two groups. Co-worker support and teamwork contributed to increased job satisfaction for all groups.

  1. Business Cycles, Financial Crises, and Stock Volatility

    OpenAIRE

    G. William Schwert

    1989-01-01

    This paper shows that stock volatility increases during recessions and financial crises from 1834-1987. The evidence reinforces the notion that stock prices are an important business cycle indicator. Using two different statistical models for stock volatility, I show that volatility increases after major financial crises. Moreover. stock volatility decreases and stock prices rise before the Fed increases margin requirements. Thus, there is little reason to believe that public policies can con...

  2. Decomposing European bond and equity volatility

    DEFF Research Database (Denmark)

    Christiansen, Charlotte

    The paper investigates volatility spillover from US and aggregate European asset markets into European national asset markets. A main contribution is that bond and equity volatilities are analyzed simultaneously. A new model belonging to the "volatilityspillover" family is suggested: The conditio...... (stock) volatilities are mainly influenced by bond (stock) effects. Global, regional, and local volatility effects are all important. The introduction of the euro is associated with a structural break....

  3. The january effect across volatility regimes

    OpenAIRE

    Agnani, Betty; Aray, Henry

    2007-01-01

    Using a Markov regime switching model, this article presents evidence on the well-known January effect on stock returns. The specification allows a distinction to be drawn between two regimes, one with high volatility and other with low volatility. We obtain a time-varying January effect that is, in general, positive and significant in both volatility regimes. However, this effect is larger in the high volatility regime. In sharp contrast with most previous literature we find two major result...

  4. Exponential Smoothing, Long Memory and Volatility Prediction

    DEFF Research Database (Denmark)

    Proietti, Tommaso

    Extracting and forecasting the volatility of financial markets is an important empirical problem. The paper provides a time series characterization of the volatility components arising when the volatility process is fractionally integrated, and proposes a new predictor that can be seen as extensi...... methods for forecasting realized volatility, and that the estimated model confidence sets include the newly proposed fractional lag predictor in all occurrences....

  5. Prevalence and determinants of child maltreatment among high school students in Southern China: A large scale school based survey

    OpenAIRE

    2008-01-01

    Abstract Background Child maltreatment can cause significant physical and psychological problems. The present study aimed to investigate the prevalence and determinants of child maltreatment in Guangzhou, China, where such issues are often considered a taboo subject. Methods A school-based survey was conducted in southern China in 2005. 24 high schools were selected using stratified random sampling strategy based on their districts and bandings. The self-administered validated Chinese version...

  6. Volatile and semivolatile organic compounds in laboratory peat fire emissions

    Science.gov (United States)

    Speciated volatile organic compounds (VOCs) and organic fine particulate matter (PM2.5) mass emission factors were determined from laboratory peat fire experiments. Peat samples originated from two wildlife reserves located near the coast of North Carolina, U.S. Gas and particula...

  7. Herbicide volatilization trumps runoff losses, a multi-year investigation

    Science.gov (United States)

    Surface runoff and volatilization are two processes critical to herbicide off-site transport. To determine the relevance of these off-site transport mechanisms, runoff and turbulent vapor fluxes were simultaneously monitored on the same site for eight years. Site location, herbicide formulations, ...

  8. Prevalence and significant determinants of post-traumatic stress disorder in a large sample of patients with multiple sclerosis.

    Science.gov (United States)

    Ostacoli, Luca; Carletto, Sara; Borghi, Martina; Cavallo, Marco; Rocci, Emanuela; Zuffranieri, Marco; Malucchi, Simona; Bertolotto, Antonio; Zennaro, Alessandro; Furlan, Pier Maria; Picci, Rocco Luigi

    2013-06-01

    Chronic and life-threatening neurodegenerative diseases may be associated with post-traumatic stress disorder (PTSD). Therefore, the current study was an investigation of the prevalence of PTSD in multiple sclerosis (MS) patients, and identification of significant determinants of PTSD. Two hundred thirty-two MS patients were consecutively recruited and screened for the presence of PTSD with the Impact of Event Scale-Revised, corroborated by the Structured Clinical Interview for DSM-IV. Furthermore, participants were administered the Hospital Anxiety and Depression Scale and the Fatigue Severity Scale. Twelve patients (12/232, i.e. 5.17 %) were diagnosed as suffering from PTSD. Levels of education, anxiety and depression were significant determinants of the presence of PTSD. The role played by the levels of education, anxiety and depression in determining the presence of PTSD has been discussed. Further research on the psychological features of neurodegenerative diseases is urgently needed in order to plan appropriate treatments and improve patients' quality of life.

  9. The XChemExplorer graphical workflow tool for routine or large-scale protein-ligand structure determination.

    Science.gov (United States)

    Krojer, Tobias; Talon, Romain; Pearce, Nicholas; Collins, Patrick; Douangamath, Alice; Brandao-Neto, Jose; Dias, Alexandre; Marsden, Brian; von Delft, Frank

    2017-03-01

    XChemExplorer (XCE) is a data-management and workflow tool to support large-scale simultaneous analysis of protein-ligand complexes during structure-based ligand discovery (SBLD). The user interfaces of established crystallographic software packages such as CCP4 [Winn et al. (2011), Acta Cryst. D67, 235-242] or PHENIX [Adams et al. (2010), Acta Cryst. D66, 213-221] have entrenched the paradigm that a `project' is concerned with solving one structure. This does not hold for SBLD, where many almost identical structures need to be solved and analysed quickly in one batch of work. Functionality to track progress and annotate structures is essential. XCE provides an intuitive graphical user interface which guides the user from data processing, initial map calculation, ligand identification and refinement up until data dissemination. It provides multiple entry points depending on the need of each project, enables batch processing of multiple data sets and records metadata, progress and annotations in an SQLite database. XCE is freely available and works on any Linux and Mac OS X system, and the only dependency is to have the latest version of CCP4 installed. The design and usage of this tool are described here, and its usefulness is demonstrated in the context of fragment-screening campaigns at the Diamond Light Source. It is routinely used to analyse projects comprising 1000 data sets or more, and therefore scales well to even very large ligand-design projects.

  10. Detection of volatile organic peroxides in indoor air.

    Science.gov (United States)

    Hong, J; Maguhn, J; Freitag, D; Kettrup, A

    2001-12-01

    A supercritical fluid extraction cell filled with adsorbent (Carbotrap and Carbotrap C) was used directly as a sampling tube to enrich volatile organic compounds in air. After sampling, the analytes were extracted by supercritical fluid CO2 with methanol as modifier. Collected organic peroxides were then determined by a RP-HPLC method developed and validated previously using post-column derivatization and fluorescence detection. Some volatile organic peroxides were found in indoor air in a new car and a newly decorated kitchen in the lower microg m(-3) range. tert-Butyl perbenzoate, di-tert-butyl peroxide, and tert-butylcumyl peroxide could be identified.

  11. Oil Volatility Risk and Expected Stock Returns

    DEFF Research Database (Denmark)

    Christoffersen, Peter; Pan, Xuhui (Nick)

    After the financialization of commodity futures markets in 2004-05 oil volatility has become a strong predictor of returns and volatility of the overall stock market. Furthermore, stocks' exposure to oil volatility risk now drives the cross-section of expected returns. The difference in average r...

  12. Volatiles in inter-specific bacterial interactions

    NARCIS (Netherlands)

    Tyc, O.; Zweers, H.; De Boer, W.; Garbeva, P.V.

    2015-01-01

    The importance of volatile organic compounds for functioning of microbes is receiving increased research attention. However, to date very little is known on how inter-specific bacterial interactions effect volatiles production as most studies have been focused on volatiles produced by monocultures o

  13. Volatiles in inter-specific bacterial interactions

    NARCIS (Netherlands)

    Tyc, O.; Zweers, H.; De Boer, W.; Garbeva, P.V.

    2015-01-01

    The importance of volatile organic compounds for functioning of microbes is receiving increased research attention. However, to date very little is known on how inter-specific bacterial interactions effect volatiles production as most studies have been focused on volatiles produced by monocultures

  14. Ammonia volatilization from intensively managed dairy pastures.

    NARCIS (Netherlands)

    Bussink, D.W.

    1996-01-01

    The objectives of this thesis are (i) to quantify NH 3 volatilization from grassland, (ii) to gain understanding of the NH3 volatilization processes on grassland and (iii) to study measures how to reduce NH 3 volatilization from gra

  15. Oil Volatility Risk and Expected Stock Returns

    DEFF Research Database (Denmark)

    Christoffersen, Peter; Pan, Xuhui (Nick)

    After the financialization of commodity futures markets in 2004-05 oil volatility has become a strong predictor of returns and volatility of the overall stock market. Furthermore, stocks' exposure to oil volatility risk now drives the cross-section of expected returns. The difference in average r...

  16. Cost Linkages Transmit Volatility Across Markets

    DEFF Research Database (Denmark)

    Nguyen, Daniel Xuyen; Schaur, Georg

    to link the domestic and export supply costs. This theoretical contribution has two new implications for the exporting firm. First, the demand volatility in the foreign market now directly affects the firm's domestic sales volatility. Second, firms hedge domestic demand volatility with exports. The model...

  17. Herbivore-induced volatile emission in black poplar: regulation and role in attracting herbivore enemies.

    Science.gov (United States)

    Clavijo McCormick, Andrea; Irmisch, Sandra; Reinecke, Andreas; Boeckler, G Andreas; Veit, Daniel; Reichelt, Michael; Hansson, Bill S; Gershenzon, Jonathan; Köllner, Tobias G; Unsicker, Sybille B

    2014-08-01

    After herbivory, plants release volatile organic compounds from damaged foliage as well as from nearby undamaged leaves that attract herbivore enemies. Little is known about what controls the volatile emission differences between damaged and undamaged tissues and how these affect the orientation of herbivore enemies. We investigated volatile emission from damaged and adjacent undamaged foliage of black poplar (Populus nigra) after herbivory by gypsy moth (Lymantria dispar) caterpillars and determined the compounds mediating the attraction of the gypsy moth parasitoid Glyptapanteles liparidis (Braconidae). Female parasitoids were more attracted to gypsy moth-damaged leaves than to adjacent non-damaged leaves. The most characteristic volatiles of damaged versus neighbouring undamaged leaves included terpenes, green leaf volatiles and nitrogen-containing compounds, such as aldoximes and nitriles. Electrophysiological recordings and olfactometer bioassays demonstrated the importance of nitrogenous volatiles. Under field conditions, parasitic Hymenoptera were more attracted to traps baited with these substances than most other compounds. The differences in volatile emission profiles between damaged and undamaged foliage appear to be regulated by jasmonate signalling and the local activation of volatile biosynthesis. We conclude that characteristic volatiles from damaged black poplar foliage are essential cues enabling parasitoids to find their hosts.

  18. Generation of saffron volatiles by thermal carotenoid degradation.

    Science.gov (United States)

    Carmona, Manuel; Zalacain, Amaya; Salinas, M Rosario; Alonso, Gonzalo L

    2006-09-06

    Generation of volatiles by thermal treatments has been studied in saffron spice for two reasons: (a) to determine volatile profile changes during simulated aging processes and (b) to study the volatile generation pathway. During the aging process, while the amounts of C10 compounds such as safranal and HTCC increase, the amounts of C9 compounds such as isophorone and 2,6,6-trimethylcyclohexane-1,4-dione decrease. A new compound tentatively identified as 4,5,6,7-tetrahydro-7,7-dimethyl-5-oxo-3H-isobenzofuranone seems to play a very important role in the aging process. The importance of this compound, structurally similar to dihydroactindiolide, was also confirmed when the saffron volatile fraction was analyzed via the degradation of the linear chain of crocetin and crocetin esters and is reported for the first time in this paper. Thermal degradation studies of zeaxanthin, crocetin, and trans and cis crocetin esters isomers allowed us to propose different mechanisms which explain saffron volatile generation depending on the crocetin ester isomer structure.

  19. Volatile Analysis by Pyrolysis of Regolith for Planetary Resource Exploration

    Science.gov (United States)

    Glavin, Daniel P.; Malespin, Charles; ten Kate, Inge L.; Getty, Stephanie A.; Holmes, Vincent E.; Mumm, Erik; Franz, Heather B.; Noreiga, Marvin; Dobson, Nick; Southard, Adrian E.; hide

    2012-01-01

    The extraction and identification of volatile resources that could be utilized by humans including water, oxygen, noble gases, and hydrocarbons on the Moon, Mars, and small planetary bodies will be critical for future long-term human exploration of these objects. Vacuum pyrolysis at elevated temperatures has been shown to be an efficient way to release volatiles trapped inside solid samples. In order to maximize the extraction of volatiles, including oxygen and noble gases from the breakdown of minerals, a pyrolysis temperature of 1400 C or higher is required, which greatly exceeds the maximum temperatures of current state-of-the-art flight pyrolysis instruments. Here we report on the recent optimization and field testing results of a high temperature pyrolysis oven and sample manipulation system coupled to a mass spectrometer instrument called Volatile Analysis by Pyrolysis of Regolith (VAPoR). VAPoR is capable of heating solid samples under vacuum to temperatures above 1300 C and determining the composition of volatiles released as a function of temperature.

  20. Price Volatility of Main Food Commodity in Banyumas Regency Indonesia

    Directory of Open Access Journals (Sweden)

    Rahmi Hayati Putri

    2016-06-01

    Full Text Available Agricultural product is commodity which tends to fluctuate. Price volatility is caused by the change of agricultural production due to climate change as well as pest and disease. Furthermore, it is also caused by the change of agricultural land and high demand of agricultural products on religious holidays. This study was conducted to examine how volatile some of main food commodities in Banyumas Regency. Secondary data analysis method with quantitative approach was used in this research. Time series data of some food commodity prices (rice IR 64, local soybean, maize, chili red peppers, onion and garlic from January 2008 – December 2013 were utilized. The coefficient of variation was calculated to determine price volatility. The result showed that the price of red chili pepper, onion and garlic was tending to volatile. The coefficient of variation ratio of those commodities was about 20% - 35%. While the price of rice, local soybean and maize was stable. The coefficient of variation ratio of those commodities was less than 9%. This study also includes some policies that can be suggested to prevent price volatility.

  1. Automated Signal Processing Applied to Volatile-Based Inspection of Greenhouse Crops

    Directory of Open Access Journals (Sweden)

    Eldert van Henten

    2010-07-01

    Full Text Available Gas chromatograph–mass spectrometers (GC-MS have been used and shown utility for volatile-based inspection of greenhouse crops. However, a widely recognized difficulty associated with GC-MS application is the large and complex data generated by this instrument. As a consequence, experienced analysts are often required to process this data in order to determine the concentrations of the volatile organic compounds (VOCs of interest. Manual processing is time-consuming, labour intensive and may be subject to errors due to fatigue. The objective of this study was to assess whether or not GC-MS data can also be automatically processed in order to determine the concentrations of crop health associated VOCs in a greenhouse. An experimental dataset that consisted of twelve data files was processed both manually and automatically to address this question. Manual processing was based on simple peak integration while the automatic processing relied on the algorithms implemented in the MetAlignTM software package. The results of automatic processing of the experimental dataset resulted in concentrations similar to that after manual processing. These results demonstrate that GC-MS data can be automatically processed in order to accurately determine the concentrations of crop health associated VOCs in a greenhouse. When processing GC-MS data automatically, noise reduction, alignment, baseline correction and normalisation are required.

  2. In Vitro Toxicity Assessment Technique for Volatile ...

    Science.gov (United States)

    The U.S. Environmental Protection Agency is tasked with evaluating the human health, environmental, and wildlife effects of over 80,000 chemicals registered for use in the environment and commerce. The challenge is that sparse chemical data exists; traditional toxicity testing methods are slow, costly, involve animal studies, and cannot keep up with a chemical registry that typically grows by at least 1000 chemicals every year. In recent years, High Throughput Screening (HTS) has been used in order to prioritize chemicals for traditional toxicity screening or to complement traditional toxicity studies. HTS is an in vitro approach of rapidly assaying a large number of chemicals for biochemical activity using robotics and automation. However, no method currently exists for screening volatile chemicals such as air pollutants in a HTS fashion. Additionally, significant uncertainty regarding in vitro to in in vivo extrapolation (IVIVE) remains. An approach to bridge the IVIVE gap and the current lack of ability to screen volatile chemicals in a HTS fashion is by using a probe molecule (PrM) technique. The proposed technique uses chemicals with empirical human pharmacokinetic data as PrMs to study toxicity of molecules with no known data for gas-phase analysis. We are currently studying the xenobiotic-metabolizing enzyme CYP2A6 using transfected BEAS-2B bronchial epithelial cell line. The CYP2A6 pathway activity is studied by the formation of cotinine from nicot

  3. Titanium Dioxide Volatility in High Temperature Water Vapor

    Science.gov (United States)

    Nguyen, QynhGiao N.

    2008-01-01

    Titanium (Ti) containing materials are of high interest to the aerospace industry due to its high temperature capability, strength, and light weight. As with most metals an exterior oxide layer naturally exists in environments that contain oxygen (i.e. air). At high temperatures, water vapor plays a key role in the volatility of materials including oxide surfaces. This study will evaluate cold pressed titanium dioxide (TiO2) powder pellets at a temperature range of 1400 C - 1200 C in water containing environments to determine the volatile hydroxyl species using the transpiration method. The water content ranged from 0-76 mole% and the oxygen content range was 0-100 mole % during the 20-250 hour exposure times. Preliminary results indicate that oxygen is not a key contributor at these temperatures and the following reaction is the primary volatile equation for all three temperatures: TiO2 (s) + H2O (g) = TiO(OH)2 (g).

  4. A Method for Software Requirement Volatility Analysis Using QFD

    Directory of Open Access Journals (Sweden)

    Yunarso Anang

    2016-10-01

    Full Text Available Changes of software requirements are inevitable during the development life cycle. Rather than avoiding the circumstance, it is easier to just accept it and find a way to anticipate those changes. This paper proposes a method to analyze the volatility of requirement by using the Quality Function Deployment (QFD method and the introduced degree of volatility. Customer requirements are deployed to software functions and subsequently to architectural design elements. And then, after determining the potential for changes of the design elements, the degree of volatility of the software requirements is calculated. In this paper the method is described using a flow diagram and illustrated using a simple example, and is evaluated using a case study.

  5. Determination of nifuroxazide in biological fluids by automated high-performance liquid chromatography with large-volume injection.

    Science.gov (United States)

    Guinebault, P R; Broquaire, M; Braithwaite, R A

    1981-01-16

    A high-performance liquid chromatographic method for the measurement of nifuroxazide in plasma is described. The technique is based on the single extraction of the drug from buffered plasma with chloroform, using nifuratel as internal standard. The chromatographic system consisted of a 15 cm x 4.6 mm I.D. stainless-steel column packed with Spherisorb ODS, 5 micrometer, and the mobile phase was acetonitrile-orthophosphoric acid (pH 2.5) (30:70). The method was able to measure accurately plasma nifuroxazide concentrations down to 2 ng . ml-1 using 2 ml of sample with no interference from endogenous compounds. The coefficients of variation of the method at 200 and 2 ng . ml-1 were 3% and 15%, respectively, and the calibration graph was linear in this range. The use of automatic injection makes the method suitable for the routine analysis of large numbers of samples.

  6. Determination of AC Characteristics of Superconducting Dipole Magnets in the Large Hadron Collider Based on Experimental Results and Simulations

    CERN Document Server

    Ambjørndalen, Sara; Verweij, Arjan

    The Large Hadron Collider (LHC) utilizes high-field superconducting Main Dipole Magnets that bend the trajectory of the beam. The LHC ring is electrically divided into eight octants, each allocating a 7 km chain of 154 Main Dipole Magnets. Dedicated de- tection and protection systems prevent irreversible magnet damage caused by quenches. Quench is a local transition from the superconducting to the normal conducting state. Triggering of such systems, along with other failure scenarios, result in fast transient phenomena. In order to analyze the consequence of such electrical transients and failures in the dipole chain, one needs a circuit model that is validated against measurements. Currently, there exists an equivalent circuit of the Main Dipole Magnet resolved at an aperture level. Each aperture model takes into account the dynamic effects occurring in the magnets, trough a lossy-inductance model and parasitic capacitances to ground. At low frequencies the Main Dipole Magnet behaves as a linear inductor. Ca...

  7. Effects of dietary rosemary and oregano volatile oil mixture on quail performance, egg traits and egg oxidative stability.

    Science.gov (United States)

    Yesilbag, D; Gezen, S S; Biricik, H; Meral, Y

    2013-01-01

    1. This study was conducted to determine the effects of volatile oil mixture on quail laying performance, egg traits and egg malondialdehyde (MDA) concentration. 2. A total of 260 Pharaoh quails (Coturnix coturnix Pharaoh) aged 6 weeks were equally divided into 5 groups of 65 (4 replicates of 13 quails each). The mixture of diets was as follows: a control treatment with 0 mg volatile oil/kg of diet; (1) 200 mg/kg rosemary volatile oil; (2) 200 mg/kg oregano volatile oil; (3) 40 mg/kg rosemary volatile oil plus 160 mg/kg oregano volatile oil (ratio 20:80) and (4) 160 mg/kg rosemary volatile oil plus 40 mg/kg oregano volatile oil (ratio 80:20). The diets were prepared fresh for each treatment. The experimental period lasted 10 weeks. 3. At the end of the experiment, there were no significant differences amongst the groups in body weight, egg weight, egg mass, egg shape index, Haugh unit, egg shell thickness or egg shell-breaking strength. 4. Diets containing rosemary volatile oil increased the egg production significantly. Feed intake significantly increased in the groups containing volatile oil mixture (groups 4 and 5). The inclusion of rosemary volatile oil at 200 mg/kg improved feed efficiency. 5. Egg albumen and egg yolk index values showed significant increases in the group given diets containing rosemary volatile oil. Egg yolk colour became darker with the addition of rosemary and oregano volatile oil. The treatment group had lower egg yolk MDA concentration than the control group. 6. It is concluded that, alone or in combination, rosemary and oregano volatile oil can be used in quail diets without adverse effects on the measured parameters. Inclusion of rosemary and oregano volatile oil in quail diets enhanced the antioxidant status of eggs.

  8. Pollinator and herbivore attraction to cucurbita floral volatiles.

    Science.gov (United States)

    Andrews, Elizabeth S; Theis, Nina; Adler, Lynn S

    2007-09-01

    Mutualists and antagonists may place conflicting selection pressures on plant traits. For example, the evolution of floral traits is typically studied in the context of attracting pollinators, but traits may incur fitness costs if they are also attractive to antagonists. Striped cucumber beetles (Acalymma vittatum) feed on cucurbits and are attracted to several volatiles emitted by Cucurbita blossoms. However, the effect of these volatiles on pollinator attraction is unknown. Our goal was to determine whether pollinators were attracted to the same or different floral volatiles as herbivorous cucumber beetles. We tested three volatiles previously found to attract cucumber beetles in a factorial design to determine attraction of squash bees (Peponapis pruinosa), the specialist pollinators of cucurbita species, as well as the specialist herbivore A. vittatum. We found that 1,2,4-trimethoxybenzene was attractive to both the pollinator and the herbivore, indole was attractive only to the herbivore, and (E)-cinnamaldehyde was attractive only to the pollinator. There were no interactions among volatiles on attraction of squash bees or cucumber beetles. Our results suggest that reduced indole emission could benefit plants by reducing herbivore attraction without loss of pollination, and that 1,2,4-trimethoxybenzene might be under conflicting selection pressure from mutualists and antagonists. By examining the attraction of both mutualists and antagonists to Cucurbita floral volatiles, we have demonstrated the potential for some compounds to influence only one type of interaction, while others may affect both interactions and possibly result in tradeoffs. These results shed light on the potential evolution of fragrance in native Cucurbita, and may have consequences for yield in agricultural settings.

  9. Level Shifts in Volatility and the Implied-Realized Volatility Relation

    DEFF Research Database (Denmark)

    Christensen, Bent Jesper; de Magistris, Paolo Santucci

    to the multivariate case of the univariate level shift technique by Lu and Perron (2008). An application to the S&P500 index and a simulation experiment show that the recently documented empirical properties of strong persistence in volatility and forecastability of future realized volatility from current implied...... volatility, which have been interpreted as long memory (or fractional integration) in volatility and fractional cointegration between implied and realized volatility, are accounted for by occasional common level shifts....

  10. Pesticide volatilization from soil: lysimeter measurements versus predictions of European registration models.

    Science.gov (United States)

    Wolters, André; Linnemann, Volker; Herbst, Michael; Klein, Michael; Schäffer, Andreas; Vereecken, Harry

    2003-01-01

    A comparison was drawn between model predictions and experimentally determined volatilization rates to evaluate the volatilization approaches of European registration models. Volatilization rates of pesticides (14C-labeled parathion-methyl, fenpropimorph, and terbuthylazine and nonlabeled chlorpyrifos) were determined in a wind-tunnel experiment after simultaneous soil surface application on Gleyic Cambisol. Both continuous air sampling, which quantifies volatile losses of 14C-organic compounds and 14CO2 separately, and the detection of soil residues allow for a mass balance of radioactivity of the 14C-labeled pesticides. Recoveries were found to be > 94% of the applied radioactivity. The following descending order of cumulative volatilization was observed: chlorpyrifos > parathion-methyl > terbuthylazine > fenpropimorph. Due to its high air-water partitioning coefficient, nonlabeled chlorpyrifos was found to have the highest cumulative volatilization (44.4%) over the course of the experiment. Volatilization flux rates were measured up to 993 microg m(-2) h(-1) during the first hours after application. Parameterization of the Pesticide Emission Assessment at Regional and Local Scales (PEARL) model and the Pesticide Leaching Model (PELMO) was performed to mirror the experimental boundary conditions. In general, model predictions deviated markedly from measured volatilization rates and showed limitations of current volatilization models, such as the uppermost compartment thickness, making an enormous influence on predicted volatilization losses. Experimental findings revealed soil moisture to be an important factor influencing volatilization from soil, yet its influence was not reflected by the model calculations. Future versions of PEARL and PELMO ought to include improved descriptions of aerodynamic resistances and soil moisture dependent soil-air partitioning coefficients.

  11. Determination of nanogram per liter concentrations of volatile organic compounds in water by capillary gas chromatography and selected ion monitoring mass spectrometry and its use to define groundwater flow directions in Edwards Aquifer, Texas

    Science.gov (United States)

    Buszka, P.M.; Rose, D.L.; Ozuna, G.B.; Groschen, G.E.

    1995-01-01

    A method has been developed to measure nanogram per liter amounts of selected volatile organic compounds (VOCs) including dichlorodifluoromethane, trichlorofluoromethane, cis-1,2-dichloroethene, trichloroethene, tetrachloroethene, and the isomers of dichlorobenzene in water. The method uses purge-and-trap techniques on a 100 mL sample, gas chromatography with a megabore capillary column, and electron impact, selected ion monitoring mass spectrometry. Minimum detection levels for these compounds ranged from 1 to 4 ng/L in water. Recoveries from organic-free distilled water and natural groundwater ranged from 70.5% for dichlorodifluoromethane to 107.8% for 1,4-dichlorobenzene. Precision was generally best for cis-1,2-dichloroethene, tetrachloroethene, and the dichlorobenzene isomers and worst for dichlorodifluoromethane and trichlorofluoromethane. Blank data indicated persistent, trace-level introduction of dichlorodifluoromethane, 1,4-dichlorobenzene, and tetrachloroemene to samples during storage and shipment at concentrations less than the method reporting limits. The largest concentrations of the selected VOCs in 27 water samples from the Edwards aquifer near San Antonio, TX, were from confined-zone wells near an abandoned landfill. The results defined a zone of water with no detectable VOCs in nearly all of the aquifer west of San Antonio and from part of the confined zone beneath San Antonio.

  12. Novel Set-Up for Low-Disturbance Sampling of Volatile and Non-volatile Compounds from Plant Roots.

    Science.gov (United States)

    Eilers, Elisabeth J; Pauls, Gerhard; Rillig, Matthias C; Hansson, Bill S; Hilker, Monika; Reinecke, Andreas

    2015-03-01

    Most studies on rhizosphere chemicals are carried out in substrate-free set-ups or in artificial substrates using sampling methods that require an air flow and may thus cause disturbance to the rhizosphere. Our study aimed to develop a simplified and inexpensive system that allows analysis of rhizosphere chemicals at experimentally less disturbed conditions. We designed a mesocosm in which volatile rhizosphere chemicals were sampled passively (by diffusion) without air- and water flow on polydimethylsiloxane-(PDMS) tubes. Dandelion (Taraxacum sect. ruderalia) was used as model plant; roots were left undamaged. Fifteen volatiles were retrieved from the sorptive material by thermal desorption for analysis by gas chromatography/mass spectrometry (GC/MS). Furthermore, three sugars were collected from the rhizosphere substrate by aqueous extraction and derivatized prior to GC/MS analysis. In order to study how the quantity of detected rhizosphere compounds depends on the type of soil or substrate, we determined the matrix-dependent recovery of synthetic rhizosphere chemicals. Furthermore, we compared sorption of volatiles on PDMS tubes with and without direct contact to the substrate. The results show that the newly designed mesocosm is suitable for low-invasive extraction of volatile and non-volatile compounds from rhizospheres. We further highlight how strongly the type of substrate and contact of PDMS tubes to the substrate affect the detectability of compounds from rhizospheres.

  13. The origin of volatiles in the Earth's mantle

    Science.gov (United States)

    Hier-Majumder, Saswata; Hirschmann, Marc M.

    2017-08-01

    The Earth's deep interior contains significant reservoirs of volatiles such as H, C, and N. Due to the incompatible nature of these volatile species, it has been difficult to reconcile their storage in the residual mantle immediately following crystallization of the terrestrial magma ocean (MO). As the magma ocean freezes, it is commonly assumed that very small amounts of melt are retained in the residual mantle, limiting the trapped volatile concentration in the primordial mantle. In this article, we show that inefficient melt drainage out of the freezing front can retain large amounts of volatiles hosted in the trapped melt in the residual mantle while creating a thick early atmosphere. Using a two-phase flow model, we demonstrate that compaction within the moving freezing front is inefficient over time scales characteristic of magma ocean solidification. We employ a scaling relation between the trapped melt fraction, the rate of compaction, and the rate of freezing in our magma ocean evolution model. For cosmochemically plausible fractions of volatiles delivered during the later stages of accretion, our calculations suggest that up to 77% of total H2O and 12% of CO2 could have been trapped in the mantle during magma ocean crystallization. The assumption of a constant trapped melt fraction underestimates the mass of volatiles in the residual mantle by more than an order of magnitude.Plain Language SummaryThe Earth's deep interior contains substantial amounts of volatile elements like C, H, and N. How these elements got sequestered in the Earth's interior has long been a topic of debate. It is generally assumed that most of these elements escaped the interior of the Earth during the first few hundred thousand years to create a primitive atmosphere, leaving the mantle reservoir nearly empty. In this work, we show that the key to this paradox involves the very early stages of crystallization of the mantle from a global magma ocean. Using numerical models, we show

  14. Determinants of bone mass and bone size in a large cohort of physically active young adult men

    Directory of Open Access Journals (Sweden)

    Garrett P

    2006-02-01

    Full Text Available Abstract The determinants of bone mineral density (BMD at multiple sites were examined in a fit college population. Subjects were 755 males (mean age = 18.7 years entering the United States Military Academy. A questionnaire assessed exercise frequency and milk, caffeine, and alcohol consumption and tobacco use. Academy staff measured height, weight, and fitness. Calcaneal BMD was measured by peripheral dual-energy x-ray absorptiometry (pDXA. Peripheral-quantitative computed tomography (pQCT was used to measure tibial mineral content, circumference and cortical thickness. Spine and hip BMD were measured by DXA in a subset (n = 159. Mean BMD at all sites was approximately one standard deviation above young normal (p

  15. Large-scale determination of sequence, structure, and function relationships in cytosolic glutathione transferases across the biosphere.

    Science.gov (United States)

    Mashiyama, Susan T; Malabanan, M Merced; Akiva, Eyal; Bhosle, Rahul; Branch, Megan C; Hillerich, Brandan; Jagessar, Kevin; Kim, Jungwook; Patskovsky, Yury; Seidel, Ronald D; Stead, Mark; Toro, Rafael; Vetting, Matthew W; Almo, Steven C; Armstrong, Richard N; Babbitt, Patricia C

    2014-04-01

    The cytosolic glutathione transferase (cytGST) superfamily comprises more than 13,000 nonredundant sequences found throughout the biosphere. Their key roles in metabolism and defense against oxidative damage have led to thousands of studies over several decades. Despite this attention, little is known about the physiological reactions they catalyze and most of the substrates used to assay cytGSTs are synthetic compounds. A deeper understanding of relationships across the superfamily could provide new clues about their functions. To establish a foundation for expanded classification of cytGSTs, we generated similarity-based subgroupings for the entire superfamily. Using the resulting sequence similarity networks, we chose targets that broadly covered unknown functions and report here experimental results confirming GST-like activity for 82 of them, along with 37 new 3D structures determined for 27 targets. These new data, along with experimentally known GST reactions and structures reported in the literature, were painted onto the networks to generate a global view of their sequence-structure-function relationships. The results show how proteins of both known and unknown function relate to each other across the entire superfamily and reveal that the great majority of cytGSTs have not been experimentally characterized or annotated by canonical class. A mapping of taxonomic classes across the superfamily indicates that many taxa are represented in each subgroup and highlights challenges for classification of superfamily sequences into functionally relevant classes. Experimental determination of disulfide bond reductase activity in many diverse subgroups illustrate a theme common for many reaction types. Finally, sequence comparison between an enzyme that catalyzes a reductive dechlorination reaction relevant to bioremediation efforts with some of its closest homologs reveals differences among them likely to be associated with evolution of this unusual reaction

  16. Determination of hydrogeological conditions in large unconfined aquifer: A case study in central Drava plain (NE Slovenia)

    Science.gov (United States)

    Keršmanc, Teja; Brenčič, Mihael

    2016-04-01

    In several countries, many unregulated landfills exits which releasing harmful contaminations to the underlying aquifer. The Kidričevo industrial complex is located in southeastern part of Drava plain in NW Slovenia. In the past during the production of alumina and aluminum approximately 11.2 million tons of wastes were deposit directly on the ground on two landfills covering an area of 61 hectares. Hydrogeological studies were intended to better characterized conditions bellow the landfill. Geological and hydrogeological conditions of Quaternary unconfined aquifer were analyzed with lithological characterization of well logs and cutting debris and XRF diffraction of silty sediments on 9 boreholes. Hydrogeological conditions: hydraulic permeability aquifer was determined with hydraulic tests and laboratory grain size analyses where empirical USBR and Hazen methods were applied. Dynamics of groundwater was determined by groundwater contour maps and groundwater level fluctuations. The impact of landfill was among chemical analyses of groundwater characterised by electrical conductivity measurements and XRF spectrometry of sand sediments. The heterogeneous Quaternary aquifer composed mainly of gravel and sand, is between 38 m and 47.5 m thick. Average hydraulic permeability of aquifer is within the decade 10-3 m/s. Average hydraulic permeability estimated on grain size curves is 6.29*10-3 m/s, and for the pumping tests is 4.0*10-3 m/s. General direction of groundwater flow is from west to east. During high water status the groundwater flow slightly changes flow direction to the southwest and when pumping station in Kidričevo (NW of landfill) is active groundwater flows to northeast. Landfills have significant impact on groundwater quality.

  17. Large-scale determination of sequence, structure, and function relationships in cytosolic glutathione transferases across the biosphere.

    Directory of Open Access Journals (Sweden)

    Susan T Mashiyama

    2014-04-01

    Full Text Available The cytosolic glutathione transferase (cytGST superfamily comprises more than 13,000 nonredundant sequences found throughout the biosphere. Their key roles in metabolism and defense against oxidative damage have led to thousands of studies over several decades. Despite this attention, little is known about the physiological reactions they catalyze and most of the substrates used to assay cytGSTs are synthetic compounds. A deeper understanding of relationships across the superfamily could provide new clues about their functions. To establish a foundation for expanded classification of cytGSTs, we generated similarity-based subgroupings for the entire superfamily. Using the resulting sequence similarity networks, we chose targets that broadly covered unknown functions and report here experimental results confirming GST-like activity for 82 of them, along with 37 new 3D structures determined for 27 targets. These new data, along with experimentally known GST reactions and structures reported in the literature, were painted onto the networks to generate a global view of their sequence-structure-function relationships. The results show how proteins of both known and unknown function relate to each other across the entire superfamily and reveal that the great majority of cytGSTs have not been experimentally characterized or annotated by canonical class. A mapping of taxonomic classes across the superfamily indicates that many taxa are represented in each subgroup and highlights challenges for classification of superfamily sequences into functionally relevant classes. Experimental determination of disulfide bond reductase activity in many diverse subgroups illustrate a theme common for many reaction types. Finally, sequence comparison between an enzyme that catalyzes a reductive dechlorination reaction relevant to bioremediation efforts with some of its closest homologs reveals differences among them likely to be associated with evolution of this

  18. The economic value of realized volatility

    DEFF Research Database (Denmark)

    Christoffersen, Peter; Feunou, Bruno; Jacobs, Kris

    2014-01-01

    Many studies have documented that daily realized volatility estimates based on intraday returns provide volatility forecasts that are superior to forecasts constructed from daily returns only. We investigate whether these forecasting improvements translate into economic value added. To do so, we...... develop a new class of affine discrete-time option valuation models that use daily returns as well as realized volatility. We derive convenient closed-form option valuation formulas, and we assess the option valuation properties using Standard & Poor’s (S&P) 500 return and option data. We find...... that realized volatility reduces the pricing errors of the benchmark model significantly across moneyness, maturity, and volatility levels....

  19. Distribution of moderately volatile trace elements in fine-grained chondrule rims in the unequilibrated CO3 chondrite, ALH A77307.

    Science.gov (United States)

    Brearley, A J; Bajt, S; Sutton, S R

    1995-10-01

    The concentrations of Ni, Cu, Zn, Ga, Ge, and Se in five, fine-grained chondrule rims in the highly unequilibrated CO3 chondrite ALH A77307 (3.0) have been determined for the first time by synchrotron X-ray fluorescence (SXRF) microprobe at Brookhaven National Laboratory. These elements are especially useful for tracing the role of condensation and evaporation processes which occurred at moderate temperatures in the solar nebula. Understanding the distribution of moderately volatile elements between matrix and chondrules is extremely important for evaluating the different models for the volatile depletions in chondritic meteorites. The data show that the trace element chemistry of rims on different chondrules is remarkably similar, consistent with data obtained for the major and minor elements by electron microprobe. These results support the idea that rims are not genetically related to individual chondrules, but all sampled the same reservoir of homogeneously mixed dust. Of the trace elements analyzed, Zn and Ga show depletions relative to CI chondrite values, but in comparison with bulk CO chondrites all the elements are enriched by approximately 1.5 to 3.5 x CO. The abundance patterns for moderately volatile elements in ALH A77307 chondrule rims closely mimic those observed in the bulk chondrite, indicating that matrix is the major reservoir for these elements. The close matching of the patterns for the volatile depleted bulk chondrite and enriched matrix is especially striking for Na, which is anomalously depleted in ALH A77307 in comparison with average CO chondrite abundances. The depletion in Na is probably attributable to the effects of leaching in Antarctica. With the exception of Na, the volatile elements show a relatively smooth decrease in abundance as a function of condensation temperature, indicating that their behavior is largely controlled by their volatility.

  20. FIELD SCREENING FOR HALOGENATED VOLATILE ORGANIC COMPOUNDS

    Energy Technology Data Exchange (ETDEWEB)

    John F. Schabron; Joseph F. Rovani Jr.; Theresa M. Bomstad

    2002-06-01

    Western Research Institute (WRI) initiated exploratory work towards the development of new field screening methodology and a test kit to measure halogenated volatile organic compounds (VOCs) in the field. Heated diode and corona discharge sensors are commonly used to detect leaks of refrigerants from air conditioners, freezers, and refrigerators. They are both selective to the presence of carbon-halogen bonds. Commercially available heated diode and corona discharge leak detectors were procured and evaluated for halogenated VOC response. The units were modified to provide a digital readout of signal related to VOC concentration. Sensor response was evaluated with carbon tetrachloride and tetrachloroethylene (perchloroethylene, PCE), which represent halogenated VOCs with and without double bonds. The response characteristics were determined for the VOCs directly in headspace in Tedlar bag containers. Quantitation limits in air were estimated. Potential interferences from volatile hydrocarbons, such as toluene and heptane, were evaluated. The effect of humidity was studied also. The performance of the new devices was evaluated in the laboratory by spiking soil samples and monitoring headspace for halogenated VOCs. A draft concept of the steps for a new analytical method was outlined. The results of the first year effort show that both devices show potential utility for future analytical method development work towards the goal of developing a portable test kit for screening halogenated VOCs in the field.