WorldWideScience

Sample records for chemical state analysis

  1. Chemical imaging and solid state analysis at compact surfaces using UV imaging

    DEFF Research Database (Denmark)

    Wu, Jian X.; Rehder, Sönke; van den Berg, Frans;

    2014-01-01

    Fast non-destructive multi-wavelength UV imaging together with multivariate image analysis was utilized to visualize distribution of chemical components and their solid state form at compact surfaces. Amorphous and crystalline solid forms of the antidiabetic compound glibenclamide...... and excipients in a non-invasive way, as well as mapping the glibenclamide solid state form. An exploratory data analysis supported the critical evaluation of the mapping results and the selection of model parameters for the chemical mapping. The present study demonstrated that the multi-wavelength UV imaging...

  2. What do molecules do when we are not looking? State sequence analysis for stochastic chemical systems.

    Science.gov (United States)

    Levin, Pavel; Lefebvre, Jérémie; Perkins, Theodore J

    2012-12-07

    Many biomolecular systems depend on orderly sequences of chemical transformations or reactions. Yet, the dynamics of single molecules or small-copy-number molecular systems are significantly stochastic. Here, we propose state sequence analysis--a new approach for predicting or visualizing the behaviour of stochastic molecular systems by computing maximum probability state sequences, based on initial conditions or boundary conditions. We demonstrate this approach by analysing the acquisition of drug-resistance mutations in the human immunodeficiency virus genome, which depends on rare events occurring on the time scale of years, and the stochastic opening and closing behaviour of a single sodium ion channel, which occurs on the time scale of milliseconds. In both cases, we find that our approach yields novel insights into the stochastic dynamical behaviour of these systems, including insights that are not correctly reproduced in standard time-discretization approaches to trajectory analysis.

  3. Chemical state analysis of conversion coatings by SR-XPS and TEY-XANES

    CERN Document Server

    Noro, H; Nagoshi, M

    2002-01-01

    Chromate coatings on galvanized steel have been studied by Synchrotron Radiation (SR) based techniques that include X-ray Photoelectron Spectroscopy (XPS) and Total-Electron-Yield X-ray Absorption Near Edge Structure (TEY-XANES). Non-destructive depth profiling of the coatings by SR-XPS reveals the enhancement of Cr sup 6 sup + in the outer surface. TEY-XANES spectroscopy based on simple specimen current measurement is demonstrated as an effective technique for analyzing chemical states of conversion coatings on general bulk substrates. The sampling depth of this technique, which exceeds several tens of nanometer, is determined by the penetration length of Auger electrons excited by X-ray and the inelastic mean free path of secondary electrons excited by inelastically scattered Auger electrons. The chemical states of phosphoric acid added chromate coatings are studied using this technique. The phosphoric acid is taken into the chromate coatings as partially changed into zinc and chromium phosphates, and the r...

  4. In situ chemical state analysis of buried polymer/metal adhesive interface by hard X-ray photoelectron spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Ozawa, Kenichi, E-mail: ozawa.k.ab@m.titech.ac.jp [Department of Chemistry and Materials Science, Tokyo Institute of Technology, Ookayama, Meguro-ku, Tokyo 152-8551 (Japan); Kakubo, Takashi; Shimizu, Katsunori; Amino, Naoya [The Yokohama Rubber Co., Ltd., Oiwake, Hiratsuka 254-8601 (Japan); Mase, Kazuhiko [Institute of Materials Structure Science, High Energy Accelerator Research Organization (KEK), Tsukuba 305-0801 (Japan); Ikenaga, Eiji; Nakamura, Tetsuya; Kinoshita, Toyohiko; Oji, Hiroshi [Japan Synchrotron Radiation Research Institute (JASRI), SPring-8, Hyogo 679-5198 (Japan)

    2014-11-30

    Highlights: • Chemical state analysis of the buried rubber/brass interface is conducted by HAXPES. • Ultrathin rubber films are prepared on the brass surface by two methods. • A high density of Cu{sub 2}S is found on the rubber side of the buried adhesive layer. • The chemical states of the buried and exposed interfaces are compared. - Abstract: Chemical state analysis of adhesive interfaces is important to understand an adhesion mechanism between two different materials. Although photoelectron spectroscopy (PES) is an ideal tool for such an analysis, the adhesive interfaces must be exposed to the surface because PES is essentially a surface sensitive technique. However, an in situ observation is possible by hard X-ray PES (HAXPES) owing to its large probing depth. In the present study, HAXPES is applied to investigate the adhesive interface between rubber and brass without exposing the interface. It is demonstrated that copper sulfides formed at the buried rubber/brass interface are distinguished from S-containing species in the rubber overlayer. The chemical state of the buried interface is compared with that of the “exposed” interface prepared by so-called a filter-paper method.

  5. Predicting the redox state and secondary structure of cysteine residues using multi-dimensional classification analysis of NMR chemical shifts.

    Science.gov (United States)

    Wang, Ching-Cheng; Lai, Wen-Chung; Chuang, Woei-Jer

    2016-09-01

    A tool for predicting the redox state and secondary structure of cysteine residues using multi-dimensional analyses of different combinations of nuclear magnetic resonance (NMR) chemical shifts has been developed. A data set of cysteine [Formula: see text], (13)C(α), (13)C(β), (1)H(α), (1)H(N), and (15)N(H) chemical shifts was created, classified according to redox state and secondary structure, using a library of 540 re-referenced BioMagResBank (BMRB) entries. Multi-dimensional analyses of three, four, five, and six chemical shifts were used to derive rules for predicting the structural states of cysteine residues. The results from 60 BMRB entries containing 122 cysteines showed that four-dimensional analysis of the C(α), C(β), H(α), and N(H) chemical shifts had the highest prediction accuracy of 100 and 95.9 % for the redox state and secondary structure, respectively. The prediction of secondary structure using 3D, 5D, and 6D analyses had the accuracy of ~90 %, suggesting that H(N) and [Formula: see text] chemical shifts may be noisy and made the discrimination worse. A web server (6DCSi) was established to enable users to submit NMR chemical shifts, either in BMRB or key-in formats, for prediction. 6DCSi displays predictions using sets of 3, 4, 5, and 6 chemical shifts, which shows their consistency and allows users to draw their own conclusions. This web-based tool can be used to rapidly obtain structural information regarding cysteine residues directly from experimental NMR data.

  6. Computational analysis of the mechanism of chemical reactions in terms of reaction phases: hidden intermediates and hidden transition States.

    Science.gov (United States)

    Kraka, Elfi; Cremer, Dieter

    2010-05-18

    Computational approaches to understanding chemical reaction mechanisms generally begin by establishing the relative energies of the starting materials, transition state, and products, that is, the stationary points on the potential energy surface of the reaction complex. Examining the intervening species via the intrinsic reaction coordinate (IRC) offers further insight into the fate of the reactants by delineating, step-by-step, the energetics involved along the reaction path between the stationary states. For a detailed analysis of the mechanism and dynamics of a chemical reaction, the reaction path Hamiltonian (RPH) and the united reaction valley approach (URVA) are an efficient combination. The chemical conversion of the reaction complex is reflected by the changes in the reaction path direction t(s) and reaction path curvature k(s), both expressed as a function of the path length s. This information can be used to partition the reaction path, and by this the reaction mechanism, of a chemical reaction into reaction phases describing chemically relevant changes of the reaction complex: (i) a contact phase characterized by van der Waals interactions, (ii) a preparation phase, in which the reactants prepare for the chemical processes, (iii) one or more transition state phases, in which the chemical processes of bond cleavage and bond formation take place, (iv) a product adjustment phase, and (v) a separation phase. In this Account, we examine mechanistic analysis with URVA in detail, focusing on recent theoretical insights (with a variety of reaction types) from our laboratories. Through the utilization of the concept of localized adiabatic vibrational modes that are associated with the internal coordinates, q(n)(s), of the reaction complex, the chemical character of each reaction phase can be identified via the adiabatic curvature coupling coefficients, A(n,s)(s). These quantities reveal whether a local adiabatic vibrational mode supports (A(n,s) > 0) or resists

  7. Chemical Security Analysis Center

    Data.gov (United States)

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

  8. Quantitative Chemical Analysis of Slag Ash of Novocherkassk State District Power Plant

    Directory of Open Access Journals (Sweden)

    Tatyana Germanovna Korotkova

    2017-02-01

    Full Text Available Quantitative chemical composition of ash and slag mix generated upon combustion of Donetsk culm is determined. It is established that ash and slag mix of Novocherkassk state district power plant (SDPP (Rostov region, Russia after coal combustion has the following composition: iron – 2.3%; mineral constituents – 75.8%; calcium oxide – 20.4%; aluminum oxide – 0.0118%; water – 1.3022%; manganese oxide – 0.18%; copper oxide – 0.0043%; plumbum – 0.0017%; it is qualified as hazard class IV for environment. Cadmium, mercury, arsenic, selenium, antimony, bismuth are contained in trace amounts < 0.1 mg/kg. In order to reduce dust emissions the cleaning stage I of gas scrubbing facility is equipped with group cyclone comprised of four cyclone units. Medium and coarse particles under the action of centrifugal force are deposited in the cyclone. This promoted decrease in dust load on bag filters, the cleaning stage II. Qualitative chemical composition of ash captured by group cyclone and that of ash captured by bag filter are determined. Cadmium, copper, plumbum, zinc, iron, manganese, and calcium are contained in coarse and fine particles captured by group cyclone and bag filter. Aluminum referred to light metals is completely captured by cyclone. The ash dust in its bulk is of dark gray color. The ash captured by cyclone contains coarse particles of black color and the ash captured bag filter contains fine particles of light colors (gray-yellow color producing silky gloss. This is characteristic for ash dust after combustion of Donetsk culm. The main component of the ash is silicon dioxide, its content in the ash captured by filter reaches 91%. These fine particles create light tone of this ash.

  9. Multivariate Quantitative Chemical Analysis

    Science.gov (United States)

    Kinchen, David G.; Capezza, Mary

    1995-01-01

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

  10. Quality Parameters and Chemical Analysis for Biodiesel Produced in the United States in 2011

    Energy Technology Data Exchange (ETDEWEB)

    Alleman, T. L.; Fouts, L.; Chupka, G.

    2013-03-01

    Samples of biodiesel (B100) from producers and terminals in 2011were tested for critical properties: free and total glycerin, flash point, cloud point, oxidation stability, cold soak filterability, and metals. Failure rates for cold soak filterability and oxidation stability were below 5%. One sample failed flash point due to excess methanol. One sample failed oxidation stability and metal content. Overall, 95% of the samples from this survey met biodiesel quality specification ASTM D6751. In 2007, a sampling of B100 from production facilities showed that nearly 90% met D6751. In samples meeting D6751, calcium was found above the method detection limit in nearly half the samples. Feedstock analysis revealed half the biodiesel was produced from soy and half was from mixed feedstocks. The saturated fatty acid methyl ester concentration of the B100 was compared to the saturated monoglyceride concentration as a percent of total monoglyceride. The real-world correlation of these properties was very good. The results of liquid chromatograph measurement of monoglycerides were compared to ASTM D6751. Agreement between the two methods was good, particularly for total monoglycerides and unsaturated monoglycerides. Because only very low levels of saturated monoglycerides measured, the two methods had more variability, but the correlation was still acceptable.

  11. Micro-strain, dislocation density and surface chemical state analysis of multication thin films

    Science.gov (United States)

    Jayaram, P.; Pradyumnan, P. P.; Karazhanov, S. Zh.

    2016-11-01

    Multication complex metal oxide thin films are rapidly expanding the class of materials with many technologically important applications. Herein this work, the surface of the pulsed laser deposited thin films of Zn2SnO4 and multinary compounds obtained by substitution/co-substitution of Sn4+ with In3+ and Ga3+ are studied by X-ray photoelectron emission spectroscopy (X-PES) method. Peaks corresponding to the elements of Zn, Sn, Ga, In and O on the film surface has been identified and contribution of the elements has been studied by the computer aided surface analysis (CASA) software. Binding energies, full-width at half maximum (FWHM), spin-orbit splitting energies, asymmetric peak-shape fitting parameters and quantification of elements in the films are discussed. Studies of structural properties of the films by x-ray diffraction (XRD) technique showed inverse spinel type lattice with preferential orientation. Micro-strain, dislocation density and crystallite sizes in the film surface have been estimated.

  12. Chemical Analysis Facility

    Data.gov (United States)

    Federal Laboratory Consortium — FUNCTION: Uses state-of-the-art instrumentation for qualitative and quantitative analysis of organic and inorganic compounds, and biomolecules from gas, liquid, and...

  13. Level crossing analysis of chemically induced dynamic nuclear polarization: Towards a common description of liquid-state and solid-state cases.

    Science.gov (United States)

    Sosnovsky, Denis V; Jeschke, Gunnar; Matysik, Jörg; Vieth, Hans-Martin; Ivanov, Konstantin L

    2016-04-14

    Chemically Induced Dynamic Nuclear Polarization (CIDNP) is an efficient method of creating non-equilibrium polarization of nuclear spins by using chemical reactions, which have radical pairs as intermediates. The CIDNP effect originates from (i) electron spin-selective recombination of radical pairs and (ii) the dependence of the inter-system crossing rate in radical pairs on the state of magnetic nuclei. The CIDNP effect can be investigated by using Nuclear Magnetic Resonance (NMR) methods. The gain from CIDNP is then two-fold: it allows one to obtain considerable amplification of NMR signals; in addition, it provides a very useful tool for investigating elusive radicals and radical pairs. While the mechanisms of the CIDNP effect in liquids are well established and understood, detailed analysis of solid-state CIDNP mechanisms still remains challenging; likewise a common theoretical frame for the description of CIDNP in both solids and liquids is missing. Difficulties in understanding the spin dynamics that lead to the CIDNP effect in the solid-state case are caused by the anisotropy of spin interactions, which increase the complexity of spin evolution. In this work, we propose to analyze CIDNP in terms of level crossing phenomena, namely, to attribute features in the CIDNP magnetic field dependence to Level Crossings (LCs) and Level Anti-Crossings (LACs) in a radical pair. This approach allows one to describe liquid-state CIDNP; the same holds for the solid-state case where anisotropic interactions play a significant role in CIDNP formation. In solids, features arise predominantly from LACs, since in most cases anisotropic couplings result in perturbations, which turn LCs into LACs. We have interpreted the CIDNP mechanisms in terms of the LC/LAC concept. This consideration allows one to find analytical expressions for a wide magnetic field range, where several different mechanisms are operative; furthermore, the LAC description gives a way to determine CIDNP sign

  14. Level crossing analysis of chemically induced dynamic nuclear polarization: Towards a common description of liquid-state and solid-state cases

    Science.gov (United States)

    Sosnovsky, Denis V.; Jeschke, Gunnar; Matysik, Jörg; Vieth, Hans-Martin; Ivanov, Konstantin L.

    2016-04-01

    Chemically Induced Dynamic Nuclear Polarization (CIDNP) is an efficient method of creating non-equilibrium polarization of nuclear spins by using chemical reactions, which have radical pairs as intermediates. The CIDNP effect originates from (i) electron spin-selective recombination of radical pairs and (ii) the dependence of the inter-system crossing rate in radical pairs on the state of magnetic nuclei. The CIDNP effect can be investigated by using Nuclear Magnetic Resonance (NMR) methods. The gain from CIDNP is then two-fold: it allows one to obtain considerable amplification of NMR signals; in addition, it provides a very useful tool for investigating elusive radicals and radical pairs. While the mechanisms of the CIDNP effect in liquids are well established and understood, detailed analysis of solid-state CIDNP mechanisms still remains challenging; likewise a common theoretical frame for the description of CIDNP in both solids and liquids is missing. Difficulties in understanding the spin dynamics that lead to the CIDNP effect in the solid-state case are caused by the anisotropy of spin interactions, which increase the complexity of spin evolution. In this work, we propose to analyze CIDNP in terms of level crossing phenomena, namely, to attribute features in the CIDNP magnetic field dependence to Level Crossings (LCs) and Level Anti-Crossings (LACs) in a radical pair. This approach allows one to describe liquid-state CIDNP; the same holds for the solid-state case where anisotropic interactions play a significant role in CIDNP formation. In solids, features arise predominantly from LACs, since in most cases anisotropic couplings result in perturbations, which turn LCs into LACs. We have interpreted the CIDNP mechanisms in terms of the LC/LAC concept. This consideration allows one to find analytical expressions for a wide magnetic field range, where several different mechanisms are operative; furthermore, the LAC description gives a way to determine CIDNP sign

  15. Chemical-state analysis of organic semiconductors using soft X-ray absorption spectroscopy combined with first-principles calculation.

    Science.gov (United States)

    Natsume, Yutaka; Kohno, Teiichiro; Minakata, Takashi; Konishi, Tokuzo; Gullikson, Eric M; Muramatsu, Yasuji

    2012-02-16

    The chemical states of organic semiconductors were investigated by total-electron-yield soft X-ray absorption spectroscopy (TEY-XAS) and first-principles calculations. The organic semiconductors, pentacene (C(22)H(14)) and pentacenequinone (C(22)H(12)O(2)), were subjected to TEY-XAS and the experimental spectra obtained were compared with the 1s core-level excited spectra of C and O atoms, calculated by a first-principles planewave pseudopotential method. Excellent agreement between the measured and the calculated spectra were obtained for both materials. Using this methodology, we examined the chemical states of the aged pentacene, and confirmed that both C-OH and C═O chemical bonds are generated by exposure to air. This result implies that not only oxygen but also humidity causes pentacene oxidation.

  16. Resolving surface chemical states in XPS analysis of first row transition metals, oxides and hydroxides: Cr, Mn, Fe, Co and Ni

    Energy Technology Data Exchange (ETDEWEB)

    Biesinger, Mark C., E-mail: biesingr@uwo.ca [Surface Science Western, University of Western Ontario, University of Western Ontario Research Park, Room LL31, 999 Collip Circle, London, Ontario, N6G 0J3 (Canada); ACeSSS (Applied Centre for Structural and Synchrotron Studies), University of South Australia, Mawson Lakes, SA 5095 (Australia); Payne, Brad P. [Department of Chemistry, University of Western Ontario, London, Ontario, N6A 5B7 (Canada); Grosvenor, Andrew P. [Department of Chemistry, University of Saskatchewan, Saskatoon, Saskatchewan, S7N 5C9 (Canada); Lau, Leo W.M. [Surface Science Western, University of Western Ontario, University of Western Ontario Research Park, Room LL31, 999 Collip Circle, London, Ontario, N6G 0J3 (Canada); Department of Chemistry, University of Western Ontario, London, Ontario, N6A 5B7 (Canada); Gerson, Andrea R.; Smart, Roger St.C. [ACeSSS (Applied Centre for Structural and Synchrotron Studies), University of South Australia, Mawson Lakes, SA 5095 (Australia)

    2011-01-15

    Chemical state X-ray photoelectron spectroscopic analysis of first row transition metals and their oxides and hydroxides is challenging due to the complexity of their 2p spectra resulting from peak asymmetries, complex multiplet splitting, shake-up and plasmon loss structure, and uncertain, overlapping binding energies. Our previous paper [M.C. Biesinger et al., Appl. Surf. Sci. 257 (2010) 887-898.] in which we examined Sc, Ti, V, Cu and Zn species, has shown that all the values of the spectral fitting parameters for each specific species, i.e. binding energy (eV), full wide at half maximum (FWHM) value (eV) for each pass energy, spin-orbit splitting values and asymmetric peak shape fitting parameters, are not all normally provided in the literature and data bases, and are necessary for reproducible, quantitative chemical state analysis. A more consistent, practical and effective approach to curve fitting was developed based on a combination of (1) standard spectra from quality reference samples, (2) a survey of appropriate literature databases and/or a compilation of literature references and (3) specific literature references where fitting procedures are available. This paper extends this approach to the chemical states of Cr, Mn, Fe, Co and Ni metals, and various oxides and hydroxides where intense, complex multiplet splitting in many of the chemical states of these elements poses unique difficulties for chemical state analysis. The curve fitting procedures proposed use the same criteria as proposed previously but with the additional complexity of fitting of multiplet split spectra which has been done based on spectra of numerous reference materials and theoretical XPS modeling of these transition metal species. Binding energies, FWHM values, asymmetric peak shape fitting parameters, multiplet peak separation and peak area percentages are presented. The procedures developed can be utilized to remove uncertainties in the analysis of surface states in nano

  17. Screening of antibiotics and chemical analysis of penicillin residue in fresh milk and traditional dairy products in Oyo state, Nigeria

    Science.gov (United States)

    Olatoye, Isaac Olufemi; Daniel, Oluwayemisi Folashade; Ishola, Sunday Ayobami

    2016-01-01

    Background and Aim: There are global public health and economic concerns on chemical residues in food of animal origin. The use of antibiotics in dairy cattle for the treatment of diseases such as mastitis has contributed to the presence of residues in dairy products. Penicillin residues as low as 1 ppb can lead to allergic reactions and shift of resistance patterns in microbial population as well as interfere with the processing of several dairy products. Antibiotic monitoring is an essential quality control measure in safe milk production. This study was aimed at determining antibiotic residue contamination and the level of penicillin in dairy products from Fulani cattle herds in Oyo State. Materials and Methods: The presence of antibiotic residues in 328 samples of fresh milk, 180 local cheese (wara), and 90 fermented milk (nono) from Southwest, Nigeria were determined using Premi® test kit (R-Biopharm AG, Germany) followed by high-performance liquid chromatography analysis of penicillin-G residue. Results: Antibiotic residues were obtained in 40.8%, 24.4% and 62.3% fresh milk, wara and nono, respectively. Penicillin-G residue was also detected in 41.1% fresh milk, 40.2% nono and 24.4% wara at mean concentrations of 15.22±0.61, 8.24±0.50 and 7.6±0.60 μg/L with 39.3%, 36.7% and 21.1%, respectively, containing penicillin residue above recommended Codex maximum residue limit (MRL) of 5 μg/L in dairy. There was no significant difference between the mean penicillin residues in all the dairy products in this study. Conclusion: The results are of food safety concern since the bulk of the samples and substantial quantities of dairy products in Oyo state contained violative levels of antibiotic residues including penicillin residues in concentrations above the MRL. This could be due to indiscriminate and unregulated administration of antibiotics to dairy cattle. Regulatory control of antibiotic use, rapid screening of milk and dairy farmers’ extension education

  18. Screening of antibiotics and chemical analysis of penicillin residue in fresh milk and traditional dairy products in Oyo state, Nigeria

    Directory of Open Access Journals (Sweden)

    Isaac Olufemi Olatoye

    2016-09-01

    Full Text Available Background and Aim: There are global public health and economic concerns on chemical residues in food of animal origin. The use of antibiotics in dairy cattle for the treatment of diseases such as mastitis has contributed to the presence of residues in dairy products. Penicillin residues as low as 1 ppb can lead to allergic reactions and shift of resistance patterns in microbial population as well as interfere with the processing of several dairy products. Antibiotic monitoring is an essential quality control measure in safe milk production. This study was aimed at determining antibiotic residue contamination and the level of penicillin in dairy products from Fulani cattle herds in Oyo State. Materials and Methods: The presence of antibiotic residues in 328 samples of fresh milk, 180 local cheese (wara, and 90 fermented milk (nono from Southwest, Nigeria were determined using Premi® test kit (R-Biopharm AG, Germany followed by high-performance liquid chromatography analysis of penicillin-G residue. Results: Antibiotic residues were obtained in 40.8%, 24.4% and 62.3% fresh milk, wara and nono, respectively. Penicillin-G residue was also detected in 41.1% fresh milk, 40.2% nono and 24.4% wara at mean concentrations of 15.22±0.61, 8.24±0.50 and 7.6±0.60 μg/L with 39.3%, 36.7% and 21.1%, respectively, containing penicillin residue above recommended Codex maximum residue limit (MRL of 5 μg/L in dairy. There was no significant difference between the mean penicillin residues in all the dairy products in this study. Conclusion: The results are of food safety concern since the bulk of the samples and substantial quantities of dairy products in Oyo state contained violative levels of antibiotic residues including penicillin residues in concentrations above the MRL. This could be due to indiscriminate and unregulated administration of antibiotics to dairy cattle. Regulatory control of antibiotic use, rapid screening of milk and dairy farmers

  19. Optical MEMS for chemical analysis and biomedicine

    CERN Document Server

    Jiang, Hongrui

    2016-01-01

    This book describes the current state of optical MEMS in chemical and biomedical analysis and brings together current trends and highlights topics representing the most exciting progress in recent years in the field.

  20. Chemical Implementation of Finite-State Machines

    Science.gov (United States)

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

    1992-01-01

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

  1. Resolving surface chemical states in XPS analysis of first row transition metals, oxides and hydroxides: Sc, Ti, V, Cu and Zn

    Energy Technology Data Exchange (ETDEWEB)

    Biesinger, Mark C., E-mail: biesingr@uwo.ca [Surface Science Western, University of Western Ontario, University of Western Ontario Research Park, Room LL31, 999 Collip Circle, London, Ontario, N6G 0J3 (Canada); ACeSSS (Applied Centre for Structural and Synchrotron Studies), University of South Australia, Mawson Lakes, SA 5095 (Australia); Lau, Leo W.M. [Surface Science Western, University of Western Ontario, University of Western Ontario Research Park, Room LL31, 999 Collip Circle, London, Ontario, N6G 0J3 (Canada); Department of Chemistry, University of Western Ontario, London, Ontario, N6A 5B7 (Canada); Gerson, Andrea R.; Smart, Roger St.C. [ACeSSS (Applied Centre for Structural and Synchrotron Studies), University of South Australia, Mawson Lakes, SA 5095 (Australia)

    2010-11-15

    Chemical state X-ray photoelectron spectroscopic analysis of first row transition metals and their oxides and hydroxides is challenging due to the complexity of the 2p spectra resulting from peak asymmetries, complex multiplet splitting, shake-up and plasmon loss structure, and uncertain, overlapping binding energies. A review of current literature shows that all values necessary for reproducible, quantitative chemical state analysis are usually not provided. This paper reports a more consistent, practical and effective approach to curve-fitting the various chemical states in a variety of Sc, Ti, V, Cu and Zn metals, oxides and hydroxides. The curve-fitting procedures proposed are based on a combination of (1) standard spectra from quality reference samples, (2) a survey of appropriate literature databases and/or a compilation of the literature references, and (3) specific literature references where fitting procedures are available. Binding energies, full-width at half maximum (FWHM) values, spin-orbit splitting values, asymmetric peak-shape fitting parameters, and, for Cu and Zn, Auger parameters values are presented. The quantification procedure for Cu species details the use of the shake-up satellites for Cu(II)-containing compounds and the exact binding energies of the Cu(0) and Cu(I) peaks. The use of the modified Auger parameter for Cu and Zn species allows for corroborating evidence when there is uncertainty in the binding energy assignment. These procedures can remove uncertainties in analysis of surface states in nano-particles, corrosion, catalysis and surface-engineered materials.

  2. Analysis of copper-rich precipitates in silicon: chemical state,gettering, and impact on multicrystalline silicon solar cellmaterial

    Energy Technology Data Exchange (ETDEWEB)

    Buonassisi, Tonio; Marcus, Matthew A.; Istratov, Andrei A.; Heuer, Matthias; Ciszek, Theodore F.; Lai, Barry; Cai, Zhonghou; Weber,Eicke R.

    2004-11-08

    In this study, synchrotron-based x-ray absorption microspectroscopy (mu-XAS) is applied to identifying the chemical states of copper-rich clusters within a variety of silicon materials, including as-grown cast multicrystalline silicon solar cell material with high oxygen concentration and other silicon materials with varying degrees of oxygen concentration and copper contamination pathways. In all samples, copper silicide (Cu3Si) is the only phase of copper identified. It is noted from thermodynamic considerations that unlike certain metal species, copper tends to form a silicide and not an oxidized compound because of the strong silicon-oxygen bonding energy; consequently the likelihood of encountering an oxidized copper particle in silicon is small, in agreement with experimental data. In light of these results, the effectiveness of aluminum gettering for the removal of copper from bulk silicon is quantified via x-ray fluorescence microscopy (mu-XRF),and a segregation coefficient is determined from experimental data to beat least (1-2)'103. Additionally, mu-XAS data directly demonstrates that the segregation mechanism of Cu in Al is the higher solubility of Cu in the liquid phase. In light of these results, possible limitations for the complete removal of Cu from bulk mc-Si are discussed.

  3. Chemical substructure analysis in toxicology

    Energy Technology Data Exchange (ETDEWEB)

    Beauchamp, R.O. Jr. [Center for Information on Toxicology and Environment, Raleigh, NC (United States)

    1990-12-31

    A preliminary examination of chemical-substructure analysis (CSA) demonstrates the effective use of the Chemical Abstracts compound connectivity file in conjunction with the bibliographic file for relating chemical structures to biological activity. The importance of considering the role of metabolic intermediates under a variety of conditions is illustrated, suggesting structures that should be examined that may exhibit potential activity. This CSA technique, which utilizes existing large files accessible with online personal computers, is recommended for use as another tool in examining chemicals in drugs. 2 refs., 4 figs.

  4. Chemical state speciation by resonant Raman scattering

    CERN Document Server

    Karydas, A G; Zarkadas, C; Paradelis, T; Kallithrakas-Kontos, N

    2002-01-01

    In the resonant Raman scattering (RRS) process the emitted photon exhibits a continuous energy distribution with a high energy cutoff limit. This cutoff energy depends on the chemical state of the element under examination. In the present work, the possibility of identifying the chemical state of V atoms by employing RRS spectroscopy with a semiconductor Si(Li) detector is investigated. A proton induced Cr K alpha x-ray beam was used as the incident radiation, having a fixed energy lower than the V K-absorption edge. The net RRS distributions extracted from the energy dispersive spectra of metallic V and its compound targets were simulated by an appropriate theoretical model. The results showed the possibility of employing RRS spectroscopy with a semiconductor detector for chemical speciation studies.

  5. Chemical Analysis of Suspected Unrecorded Alcoholic Beverages from the States of São Paulo and Minas Gerais, Brazil

    Directory of Open Access Journals (Sweden)

    Giuseppina Negri

    2015-01-01

    Full Text Available Our study analyzed 152 samples of alcoholic beverages collected from the states of São Paulo and Minas Gerais, Brazil, using gas chromatography with flame ionization detection (GC-FID and mass spectrometry (GC-MS, Fourier transform infrared spectroscopy (FT-IR, and inductively coupled plasma atomic emission spectrometry (ICP-AES. The methanol content varied from 20 to 180 ppm in 28 samples, and the limit of the accepted level of 200 ppm was exceeded in only one sample. High content of cyanide derivatives and ethyl carbamate, above the accepted level of 150 ppb, was observed in 109 samples. Carbonyl compounds were also observed in 111 samples, showing hydroxy 2-propanone, 4-methyl-4-hepten-3-one, furfural, and 2-hydroxyethylcarbamate as main constituents. Copper was found at concentrations above 5 ppm in 26 samples; the maximum value observed was 28 ppm. This work evaluated the human health risk associated with the poor quality of suspected unrecorded alcohols beverages.

  6. ¹³C solid-state NMR analysis of the most common pharmaceutical excipients used in solid drug formulations, Part I: Chemical shifts assignment.

    Science.gov (United States)

    Pisklak, Dariusz Maciej; Zielińska-Pisklak, Monika Agnieszka; Szeleszczuk, Łukasz; Wawer, Iwona

    2016-04-15

    Solid-state NMR is an excellent and useful method for analyzing solid-state forms of drugs. In the (13)C CP/MAS NMR spectra of the solid dosage forms many of the signals originate from the excipients and should be distinguished from those of active pharmaceutical ingredient (API). In this work the most common pharmaceutical excipients used in the solid drug formulations: anhydrous α-lactose, α-lactose monohydrate, mannitol, sucrose, sorbitol, sodium starch glycolate type A and B, starch of different origin, microcrystalline cellulose, hypromellose, ethylcellulose, methylcellulose, hydroxyethylcellulose, sodium alginate, magnesium stearate, sodium laurilsulfate and Kollidon(®) were analyzed. Their (13)C CP/MAS NMR spectra were recorded and the signals were assigned, employing the results (R(2): 0.948-0.998) of GIPAW calculations and theoretical chemical shifts. The (13)C ssNMR spectra for some of the studied excipients have not been published before while for the other signals in the spectra they were not properly assigned or the assignments were not correct. The results summarize and complement the data on the (13)C ssNMR analysis of the most common pharmaceutical excipients and are essential for further NMR studies of API-excipient interactions in the pharmaceutical formulations.

  7. Chemical state analysis of trace-level alkali metals sorbed in micaceous oxide by total reflection X-ray photoelectron spectroscopy

    Science.gov (United States)

    Baba, Y.; Shimoyama, I.; Hirao, N.

    2016-10-01

    In order to determine the chemical states of radioactive cesium (137Cs or 134Cs) sorbed in clay minerals, chemical states of cesium as well as the other alkali metals (sodium and rubidium) sorbed in micaceous oxides have been investigated by X-ray photoelectron spectroscopy (XPS). Since the number of atoms in radioactive cesium is extremely small, we specially focused on chemical states of trace-level alkali metals. For this purpose, we have measured XPS under X-ray total reflection (TR) condition. For cesium, it was shown that ultra-trace amount of cesium down to about 100 pg cm-2 can be detected by TR-XPS. This amount corresponds to about 200 Bq of 137Cs (t1/2 = 30.2 y). It was demonstrated that ultra-trace amount of cesium corresponding to radioactive cesium level can be measured by TR-XPS. As to the chemical states, it was found that core-level binding energy in TR-XPS for trace-level cesium shifted to lower-energy side compared with that for thicker layer. A reverse tendency is observed in sodium. Based on charge transfer within a simple point-charge model, it is concluded that chemical bond between alkali metal and micaceous oxide for ultra-thin layer is more polarized that for thick layer.

  8. Chemical State Mapping of Degraded B4C Control Rod Investigated with Soft X-ray Emission Spectrometer in Electron Probe Micro-analysis

    Science.gov (United States)

    Kasada, R.; Ha, Y.; Higuchi, T.; Sakamoto, K.

    2016-05-01

    B4C is widely used as control rods in light water reactors, such as the Fukushima Daiichi nuclear power plant, because it shows excellent neutron absorption and has a high melting point. However, B4C can melt at lower temperatures owing to eutectic interactions with stainless steel and can even evaporate by reacting with high-temperature steam under severe accident conditions. To reduce the risk of recriticality, a precise understanding of the location and chemical state of B in the melt core is necessary. Here we show that a novel soft X-ray emission spectrometer in electron probe microanalysis can help to obtain a chemical state map of B in a modeled control rod after a high-temperature steam oxidation test.

  9. Gas phase chemical detection with an integrated chemical analysis system

    Energy Technology Data Exchange (ETDEWEB)

    CASALNUOVO,STEPHEN A.; FRYE-MASON,GREGORY CHARLES; KOTTENSTETTE,RICHARD; HELLER,EDWIN J.; MATZKE,CAROLYN M.; LEWIS,PATRICK R.; MANGINELL,RONALD P.; BACA,ALBERT G.; HIETALA,VINCENT M.

    2000-04-12

    Microfabrication technology has been applied to the development of a miniature, multi-channel gas phase chemical laboratory that provides fast response, small size, and enhanced versatility and chemical discrimination. Each analysis channel includes a sample preconcentrator followed by a gas chromatographic separator and a chemically selective surface acoustic wave detector array to achieve high sensitivity and selectivity. The performance of the components, individually and collectively, is described.

  10. Quantum Chemical Strain Analysis For Mechanochemical Processes.

    Science.gov (United States)

    Stauch, Tim; Dreuw, Andreas

    2017-03-24

    The use of mechanical force to initiate a chemical reaction is an efficient alternative to the conventional sources of activation energy, i.e., heat, light, and electricity. Applications of mechanochemistry in academic and industrial laboratories are diverse, ranging from chemical syntheses in ball mills and ultrasound baths to direct activation of covalent bonds using an atomic force microscope. The vectorial nature of force is advantageous because specific covalent bonds can be preconditioned for rupture by selective stretching. However, the influence of mechanical force on single molecules is still not understood at a fundamental level, which limits the applicability of mechanochemistry. As a result, many chemists still resort to rules of thumb when it comes to conducting mechanochemical syntheses. In this Account, we show that comprehension of mechanochemistry at the molecular level can be tremendously advanced by quantum chemistry, in particular by using quantum chemical force analysis tools. One such tool is the JEDI (Judgement of Energy DIstribution) analysis, which provides a convenient approach to analyze the distribution of strain energy in a mechanically deformed molecule. Based on the harmonic approximation, the strain energy contribution is calculated for each bond length, bond angle and dihedral angle, thus providing a comprehensive picture of how force affects molecules. This Account examines the theoretical foundations of quantum chemical force analysis and provides a critical overview of the performance of the JEDI analysis in various mechanochemical applications. We explain in detail how this analysis tool is to be used to identify the "force-bearing scaffold" of a distorted molecule, which allows both the rationalization and the optimization of diverse mechanochemical processes. More precisely, we show that the inclusion of every bond, bending and torsion of a molecule allows a particularly insightful discussion of the distribution of mechanical

  11. [Laboratory chemical analysis in ascites].

    Science.gov (United States)

    Satz, N

    1991-04-13

    Chemical analysis of ascitic fluid may be helpful in determining the underlying disease. We discuss the diagnostic accuracy of the common and newer chemical parameters (protein, LDH, lactate, glucose, cholesterol, triglycerides, phospholipids, fibronectin, albumin gradient [value of serum minus value of ascites], ferritin, tumor markers, immunomodulators, leukocytes, bacterial and cytologic examinations). We also review the pathogenesis and clinical findings of the most frequent ascites forms (benign hepatic, infective, malignant ascites, ascites associated with liver metastases or hepatocellular carcinoma, cardiac and pancreatic ascites) and the most important diagnosis criteria. In the malignant ascites a high cholesterol, a narrow albumin gradient or a high ferritin value have high diagnostic accuracy, but diagnosis is by the finding of malignant cells. For the diagnosis of infective ascites, bacteriology is mandatory even though the results are negative in most cases, particularly in spontaneous bacterial peritonitis where diagnosis has to be established clinically, by a low pH or by a high leukocyte count. Benign hepatic ascites is diagnosed by demonstrating an underlying chronic liver disease and laboratory examinations of the peritoneal fluid to exclude other causes. The laboratory tests in ascites associated with liver metastases or with hepatocellular carcinoma were similar to those in benign hepatic ascites and the two ascites forms must be separated by other clinical and technical findings. Pancreatic ascites can easily be distinguished from the other forms by the high amylase and lipase content.

  12. State-to-state dynamics of elementary chemical reactions using Rydberg H-atom translational spectroscopy

    Science.gov (United States)

    Yang, Xueming

    In this review, a few examples of state-to-state dynamics studies of both unimolecular and bimolecular reactions using the H-atom Rydberg tagging TOF technique were presented. From the H2O photodissociation at 157 nm, a direction dissociation example is provided, while photodissociation of H2O at 121.6 has provided an excellent dynamical case of complicated, yet direct dissociation process through conical intersections. The studies of the O(1D) + H2 → OH + H reaction has also been reviewed here. A prototype example of state-to-state dynamics of pure insertion chemical reaction is provided. Effect of the reagent rotational excitation and the isotope effect on the dynamics of this reaction have also been investigated. The detailed mechanism for abstraction channel in this reaction has also been closely studied. The experimental investigations of the simplest chemical reaction, the H3 system, have also been described here. Through extensive collaborations between theory and experiment, the mechanism for forward scattering product at high collision energies for the H + HD reaction was clarified, which is attributed to a slow down mechanism on the top of a quantized barrier transition state. Oscillations in the product quantum state resolved different cross sections have also been observed in the H + D2 reaction, and were attributed to the interference of adiabatic transition state pathways from detailed theoretical analysis. The results reviewed here clearly show the significant advances we have made in the studies of the state-to-state molecular reaction dynamics.

  13. Comparison among chemical, mineralogical and physical analysis from alluvial clays from counties of Southwest of Minas Gerais state (Brazil); Comparacao entre as analises quimicas, mineralogicas e tecnologicas das argilas aluvionares de alguns municipios do sudoeste de Minas Gerais

    Energy Technology Data Exchange (ETDEWEB)

    Gaspar Junior, L.A., E-mail: lineo.gaspar@unifal-mg.edu.br [Universidade Federal de Alfenas (UNIALFENAS), MG (Brazil). Instituto de Ciencias da Natureza; Varajao, A.F.D.C. [Universidade Federal de Ouro Preto (UFOP), MG (Brazil). Escola de Minas; Souza, M.H.O. [Universidade Federal de Uberlandia (UFU), MG (Brazil). Departamento de Geografia; Moreno, M.M.T. [Universidade Estadual Paulista Julio de Mesquita Filho (UNESP), Rio Claro, SP (Brazil). Departamento de Petrologia e Metalogenia

    2011-07-01

    The studied area is located in the southwestern portion of Minas Gerais State, encompassing the counties of Alfenas, Areado, Machado, Poco Fundo, Campestre, Serrania, Monte Belo, Bandeira do Sul, Botelhos and Cabo Verde. This region is dominated by strongly weathered pre-cambrian rocks in association with colluvial-alluvial sediments. The present work consisted in a comparison among the mineralogical (X-Ray Diffraction), textural (Laser Granulometry), chemical (X-Ray Fluorescence) and technological (mechanical resistance, water absorption, etc, made in specimen tests) properties of the clays collected on potteries located in these counties. The mineralogical and chemical analysis displayed the kaolinitic nature of the clays from this region, showing also small amount of interlayered clays and large amount of quartz. The best results of physical analysis were obtained for clays from the counties of Cabo Verde and Monte Belo due to the presence of lower values of SiO{sub 2} (quartz) associated with a finer particle size distribution. (author)

  14. Protein's native state stability in a chemically induced denaturation mechanism.

    Science.gov (United States)

    Olivares-Quiroz, L; Garcia-Colin, L S

    2007-05-21

    In this work, we present a generalization of Zwanzig's protein unfolding analysis [Zwanzig, R., 1997. Two-state models of protein folding kinetics. Proc. Natl Acad. Sci. USA 94, 148-150; Zwanzig, R., 1995. Simple model of protein folding kinetics. Proc. Natl Acad. Sci. USA 92, 9801], in order to calculate the free energy change Delta(N)(D)F between the protein's native state N and its unfolded state D in a chemically induced denaturation. This Extended Zwanzig Model (EZM) is both based on an equilibrium statistical mechanics approach and the inclusion of experimental denaturation curves. It enables us to construct a suitable partition function Z and to derive an analytical formula for Delta(N)(D)F in terms of the number K of residues of the macromolecule, the average number nu of accessible states for each single amino acid and the concentration C(1/2) where the midpoint of the ND transition occurs. The results of the EZM for proteins where chemical denaturation follows a sigmoidal-type profile, as it occurs for the case of the T70N human variant of lysozyme (PDB code: T70N) [Esposito, G., et al., 2003. J. Biol. Chem. 278, 25910-25918], can be splitted into two lines. First, EZM shows that for sigmoidal denaturation profiles, the internal degrees of freedom of the chain play an outstanding role in the stability of the native state. On the other hand, that under certain conditions DeltaF can be written as a quadratic polynomial on concentration C(1/2), i.e., DeltaF approximately aC(1/2)(2)+bC(1/2)+c, where a,b,c are constant coefficients directly linked to protein's size K and the averaged number of non-native conformations nu. Such functional form for DeltaF has been widely known to fit experimental measures in chemically induced protein denaturation [Yagi, M., et al., 2003. J. Biol. Chem. 278, 47009-47015; Asgeirsson, B., Guojonsdottir, K., 2006. Biochim. Biophys. Acta 1764, 190-198; Sharma, S., et al., 2006. Protein Pept. Lett. 13(4), 323-329; Salem, M., et al

  15. Addressing the chemical sorcery of "GaI": benefits of solid-state analysis aiding in the synthesis of P→Ga coordination compounds.

    Science.gov (United States)

    Malbrecht, Brian J; Dube, Jonathan W; Willans, Mathew J; Ragogna, Paul J

    2014-09-15

    The differing structures and reactivities of "GaI" samples prepared with different reaction times have been investigated in detail. Analysis by FT-Raman spectroscopy, powder X-ray diffraction, (71)Ga solid-state NMR spectroscopy, and (127)I nuclear quadrupole resonance (NQR) provides concrete evidence for the structure of each "GaI" sample prepared. These techniques are widely accessible and can be implemented quickly and easily to identify the nature of the "GaI" in hand. The "GaI" prepared from exhaustive reaction times (100 min) is shown to possess Ga2I3 and an overall formula of [Ga(0)]2[Ga(+)]2[Ga2I6(2-)], while the "GaI" prepared with the shortest reaction time (40 min) contains GaI2 and has the overall formula [Ga(0)]2[Ga(+)][GaI4(-)]. Intermediate "GaI" samples were consistently shown to be fractionally composed of each of these two preceding formulations and no other distinguishable phases. These "GaI" phases were then shown to give unique products upon reactions with the anionic bis(phosphino)borate ligand class. The reaction of the early-phase "GaI" gives rise to a unique phosphine Ga(II) dimeric coordination compound (3), which was isolated reproducibly in 48% yield and convincingly characterized. A base-stabilized GaI→GaI3 fragment (4) was also isolated using the late-phase "GaI" and characterized by multinuclear NMR spectroscopy and X-ray crystallography. These compounds can be considered unique examples of low-oxidation-state P→Ga coordination compounds and possess relatively long Ga-P bond lengths in the solid-state structures. The anionic borate backbone therefore results in interesting architectures about gallium that have not been observed with neutral phosphines.

  16. Complex vibrational analysis of an antiferroelectric liquid crystal based on solid-state oriented quantum chemical calculations and experimental molecular spectroscopy.

    Science.gov (United States)

    Drużbicki, Kacper; Mikuli, Edward; Kocot, Antoni; Ossowska-Chruściel, Mirosława Danuta; Chruściel, Janusz; Zalewski, Sławomir

    2012-08-02

    The experimental and theoretical vibrational spectroscopic study of one of a novel antiferroelectric liquid crystals (AFLC), known under the MHPSBO10 acronym, have been undertaken. The interpretation of both FT-IR and FT-Raman spectra was focused mainly on the solid-state data. To analyze the experimental results along with the molecular properties, density functional theory (DFT) computations were performed using several modern theoretical approaches. The presented calculations were performed within the isolated molecule model, probing the performance of modern exchange-correlations functionals, as well as going beyond, i.e., within hybrid (ONIOM) and periodic boundary conditions (PBC) methodologies. A detailed band assignment was supported by the normal-mode analysis with SQM ab initio force field scaling. The results are supplemented by the noncovalent interactions analysis (NCI). The relatively noticeable spectral differences observed upon Crystal to AFLC phase transition have also been reported. For the most prominent vibrational modes, the geometries of the transition dipole moments along with the main components of vibrational polarizability were analyzed in terms of the molecular frame. One of the goals of the paper was to optimize the procedure of solid-state calculations to obtain the results comparable with the all electron calculations, performed routinely for isolated molecules, and to test their performance. The presented study delivers a complex insight into the vibrational spectrum with a noticeable improvement of the theoretical results obtained for significantly attracting mesogens using modern molecular modeling approaches. The presented modeling conditions are very promising for further description of similar large molecular crystals.

  17. Functional Analysis for Chemical Engineers.

    Science.gov (United States)

    Ramkrishna, D.

    1979-01-01

    Described is a graduate level engineering course on functional analysis offered at Purdue University. The course restricts itself to linear problems, specifically analysis of linear operators on vector spaces. Key applications in the course demonstrating the utility of abstract formulations are presented. (BT)

  18. Spectroscopic Chemical Analysis Methods and Apparatus

    Science.gov (United States)

    Hug, William F. (Inventor); Reid, Ray D. (Inventor); Bhartia, Rohit (Inventor); Lane, Arthur L. (Inventor)

    2017-01-01

    Spectroscopic chemical analysis methods and apparatus are disclosed which employ deep ultraviolet (e.g. in the 200 nm to 300 nm spectral range) electron beam pumped wide bandgap semiconductor lasers, incoherent wide bandgap semiconductor light emitting devices, and hollow cathode metal ion lasers to perform non-contact, non-invasive detection of unknown chemical analytes. These deep ultraviolet sources enable dramatic size, weight and power consumption reductions of chemical analysis instruments. In some embodiments, Raman spectroscopic detection methods and apparatus use ultra-narrow-band angle tuning filters, acousto-optic tuning filters, and temperature tuned filters to enable ultra-miniature analyzers for chemical identification. In some embodiments Raman analysis is conducted along with photoluminescence spectroscopy (i.e. fluorescence and/or phosphorescence spectroscopy) to provide high levels of sensitivity and specificity in the same instrument.

  19. Chemical sensing in process analysis.

    Science.gov (United States)

    Hirschfeld, T; Callis, J B; Kowalski, B R

    1984-10-19

    Improvements in process control, which determine production efficiency and product quality, are critically dependent upon on-line process analysis. The technology of the required instrumentation will be substantially expanded by advances in sensing devices. In the future, the hardware will consist of sensor arrays and miniaturized instruments fabricated by microlithography and silicon micromachining. Chemometrics will be extensively used in software to provide error detection, selfcalibration, and correction as well as multivariate data analysis for the determination of anticipated and unanticipated species. A number of examples of monolithically fabricated sensors now exist and more will be forthcoming as the new paradigms and new tools are widely adopted. A trend toward not only on-line but even in-product sensors is becoming discernible.

  20. 40 CFR 761.253 - Chemical analysis.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Chemical analysis. 761.253 Section 761.253 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) TOXIC SUBSTANCES CONTROL ACT... analysis. (a) Extract PCBs from the standard wipe sample collection medium and clean-up the extracted...

  1. Quantum-State Controlled Chemical Reactions of Ultracold KRb Molecules

    CERN Document Server

    Ospelkaus, S; Wang, D; de Miranda, M H G; Neyenhuis, B; Quéméner, G; Julienne, P S; Bohn, J L; Jin, D S; Ye, J

    2009-01-01

    How does a chemical reaction proceed at ultralow temperatures? Can simple quantum mechanical rules such as quantum statistics, single scattering partial waves, and quantum threshold laws provide a clear understanding for the molecular reactivity under a vanishing collision energy? Starting with an optically trapped near quantum degenerate gas of polar $^{40}$K$^{87}$Rb molecules prepared in their absolute ground state, we report experimental evidence for exothermic atom-exchange chemical reactions. When these fermionic molecules are prepared in a single quantum state at a temperature of a few hundreds of nanoKelvins, we observe p-wave-dominated quantum threshold collisions arising from tunneling through an angular momentum barrier followed by a near-unity probability short-range chemical reaction. When these molecules are prepared in two different internal states or when molecules and atoms are brought together, the reaction rates are enhanced by a factor of 10 to 100 due to s-wave scattering, which does not ...

  2. Reaction diffusion and solid state chemical kinetics handbook

    CERN Document Server

    Dybkov, V I

    2010-01-01

    This monograph deals with a physico-chemical approach to the problem of the solid-state growth of chemical compound layers and reaction-diffusion in binary heterogeneous systems formed by two solids; as well as a solid with a liquid or a gas. It is explained why the number of compound layers growing at the interface between the original phases is usually much lower than the number of chemical compounds in the phase diagram of a given binary system. For example, of the eight intermetallic compounds which exist in the aluminium-zirconium binary system, only ZrAl3 was found to grow as a separate

  3. Chemical analysis of aquatic pheromones in fish.

    Science.gov (United States)

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

    2013-01-01

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

  4. Chemical state of fission products in irradiated uranium carbide fuel

    Science.gov (United States)

    Arai, Yasuo; Iwai, Takashi; Ohmichi, Toshihiko

    1987-12-01

    The chemical state of fission products in irradiated uranium carbide fuel has been estimated by equilibrium calculation using the SOLGASMIX-PV program. Solid state fission products are distributed to the fuel matrix, ternary compounds, carbides of fission products and intermetallic compounds among the condensed phases appearing in the irradiated uranium carbide fuel. The chemical forms are influenced by burnup as well as stoichiometry of the fuel. The results of the present study almost agree with the experimental ones reported for burnup simulated carbides.

  5. Topological engineering of glass for modulating chemical state of dopants.

    Science.gov (United States)

    Zhou, Shifeng; Guo, Qiangbing; Inoue, Hiroyuki; Ye, Qun; Masuno, Atsunobu; Zheng, Binbin; Yu, Yongze; Qiu, Jianrong

    2014-12-17

    A novel approach to modulating the chemical state of dopants by engineering the topological features of a glass matrix is presented. The method allows selective stabilization of dopants on a wide range of length scales, from dispersed ions to aggregated clusters to nanoparticles, leading to various intriguing optical phenomena, such as great emission enhancement and ultra-broadband optical amplification.

  6. Chemical and instrumental approaches to cheese analysis.

    Science.gov (United States)

    Subramanian, Anand; Rodriguez-Saona, Luis

    2010-01-01

    Overcoming the complexity of cheese matrix to reliably analyze cheese composition, flavor, and ripening changes has been a challenge. Several sample isolation or fractionation methods, chemical and enzymatic assays, and instrumental methods have been developed over the decades. While some of the methods are well established standard methods, some still need to be researched and improved. This chapter reviews the chemical and instrumental methods available to determine cheese composition and monitor biochemical events (e.g., glycolysis, lipolysis, and proteolysis) during cheese ripening that lead to the formation of cheese flavor. Chemical and enzymatic methods available for analysis of cheese composition (fat, protein, lactose, salt, nitrogen content, moisture, etc.) are presented. Electrophoretic, chromatographic, and spectroscopic techniques are also reviewed in the light of their application to monitor cheese ripening and flavor compounds. Novel instrumental methods based on Fourier-transform infrared spectroscopy that are currently being researched and applied to cheese analysis are introduced.

  7. Enhanced UVB emission and analysis of chemical states of Ca5(PO4)3OH:Gd3+,Pr3+ phosphor prepared by co-precipitation

    Science.gov (United States)

    Mokoena, P. P.; Nagpure, I. M.; Kumar, Vinay; Kroon, R. E.; Olivier, E. J.; Neethling, J. H.; Swart, H. C.; Ntwaeaborwa, O. M.

    2014-08-01

    Hydroxyapatite (Ca5(PO4)3OH) is a well-known bioceramic material used in medical applications because of its ability to form direct chemical bonds with living tissues. This mineral is currently used as a host for rare-earth ions (e.g. Gd3+, Pr3+, Tb3+, etc.) to prepare phosphors that can be used in light emitting devices of different types. In this study Ca5(PO4)3OH:Gd3+,Pr3+ phosphors were prepared by the co-precipitation method and were characterised by x-ray diffraction, x-ray photoelectron spectroscopy, scanning electron microscopy, high resolution transmission electron microscopy, energy dispersive x-ray spectroscopy and photoluminescence spectroscopy. The x-ray diffraction pattern was consistent with the hexagonal phase of Ca5(PO4)3OH referenced in JCPDS card number 73-0293. The x-ray photoelectron spectroscopy data indicated that Ca2+ occupied two different lattice sites, referred to as Ca1 and Ca2. The photoluminescence data exhibited a narrowband emission located at 313 nm, which is associated with the 6P7/2→8S7/2 transition of the Gd3+ ion. This emission is classified as ultraviolet B and it is suitable for use in phototherapy lamps to treat various skin diseases. The photoluminescence intensity of the 313 nm emission was enhanced considerably by Pr3+ co-doping.

  8. Analysis of chemical drugs registered by State Food and Drug Administration in 2009%2009年SFDA批准注册的国产化学药品统计分析

    Institute of Scientific and Technical Information of China (English)

    李文哲; 陈昊; 李金平; 付君英; 舒丽芯

    2011-01-01

    Objective To investigate and analyze the distribution of chemical drugs registered by State Food and Drug Administration ( SFDA) in 2009. Methods The data of registered chemical drugs in 2009 including names, approval numbers, medication classifications and whether it belongs to national essential drugs or not were collected from SFDA website. Statistical analysis was implemented by Excel. Results 1 583 chemical drugs were registered which involved 489 generic chemical drugs. The most registered drugs according approval numbers were antibacterial agents, central nervous system agents and digestive system agents in turn. Conclusion The situation of chemical drugs registration in 2009 was still unsatisfied. The distribution of registration categories couldn't meet the requirement of public. The same generic drug had too much approval numbers. The productions of Antibacterial agents were competitive. A new indication of small climax of essential drugs registration appears at the same time.%目的 了解和分析2009年我国新注册的化学药品分布情况.方法 全面检索国家食品药品监督管理局数据库和相关资源,登记2009年注册的国产化学药品的名称、批准文号、药物化学治疗分类、是否属国家基本药物等,然后运用Excel进行分类汇总分析.结果 2009年共注册国产化学药品1 583个,涉及通用名药物489个,药品批准文号数量排序前三位的依次为抗微生物药物、作用于中枢神经系统的药物和作用于消化系统的药物.结论 2009年国产化学药品注册依然存在药品注册与需求不完全一致、个别药品“一药多号”、抗微生物药物生产竞争激烈等问题,同时也出现基本药物注册小高峰等新迹象.

  9. 3D thermo-chemical-mechanical analysis of the pultrusion process

    DEFF Research Database (Denmark)

    Baran, Ismet; Hattel, Jesper Henri; Tutum, Cem C.

    2013-01-01

    In the present study, a 3D Eulerian thermo-chemical analysis is sequentially coupled with a 3D Lagrangian quasi static mechanical analysis of the pultrusion process. The temperature and degree of cure profiles at the steady state are first calculated in the thermo-chemical analysis...

  10. Chemical abundance analysis of 19 barium stars

    CERN Document Server

    Yang, G C; Spite, M; Chen, Y Q; Zhao, G; Zhang, B; Liu, G Q; Liu, Y J; Liu, N; Deng, L C; Spite, F; Hill, V; Zhang, C X

    2016-01-01

    We aim at deriving accurate atmospheric parameters and chemical abundances of 19 barium (Ba) stars, including both strong and mild Ba stars, based on the high signal-to-noise ratio and high resolution Echelle spectra obtained from the 2.16 m telescope at Xinglong station of National Astronomical Observatories, Chinese Academy of Sciences. The chemical abundances of the sample stars were obtained from an LTE, plane-parallel and line-blanketed atmospheric model by inputting the atmospheric parameters (effective temperatures, surface gravities, metallicity and microturbulent velocity) and equivalent widths of stellar absorption lines. These samples of Ba stars are giants indicated by atmospheric parameters, metallicities and kinematic analysis about UVW velocity. Chemical abundances of 17 elements were obtained for these Ba stars. Their light elements (O, Na, Mg, Al, Si, Ca, Sc, Ti, V, Cr, Mn and Ni) are similar to the solar abundances. Our samples of Ba stars show obvious overabundances of neutron-capture (n-ca...

  11. Chemical state of fission products in irradiated UO 2

    Science.gov (United States)

    Imoto, S.

    1986-08-01

    The chemical state of fission products in irradiated UO 2 fuel has been estimated for FBR as well as LWR on the basis of equilibrium calculation with the SOLGASMIX-PV code. The system considered for the calculation is composed of a gas phase, a CaF 2 type oxide phase, three grey phases, a noble metal alloy, a mixed telluride phase and several other phases each consisting of single compound. The distribution of elements into these phases and the amount of chemical species in each phase at different temperatures are obtained as a function of oxygen potential for LWR and FBR. Changes of the chemical potential of the fuel-fission products system during burnup are also evaluated with particular attention to the difference between LWR and FBR. Some informations obtained by the calculation are compared with the results of post irradiation examination of UO 2 fuels.

  12. State estimation of chemical engineering systems tending to multiple solutions

    Directory of Open Access Journals (Sweden)

    N. P. G. Salau

    2014-09-01

    Full Text Available A well-evaluated state covariance matrix avoids error propagation due to divergence issues and, thereby, it is crucial for a successful state estimator design. In this paper we investigate the performance of the state covariance matrices used in three unconstrained Extended Kalman Filter (EKF formulations and one constrained EKF formulation (CEKF. As benchmark case studies we have chosen: a a batch chemical reactor with reversible reactions whose system model and measurement are such that multiple states satisfy the equilibrium condition and b a CSTR with exothermic irreversible reactions and cooling jacket energy balance whose nonlinear behavior includes multiple steady-states and limit cycles. The results have shown that CEKF is in general the best choice of EKF formulations (even if they are constrained with an ad hoc clipping strategy which avoids undesired states for such case studies. Contrary to a clipped EKF formulation, CEKF incorporates constraints into an optimization problem, which minimizes the noise in a least square sense preventing a bad noise distribution. It is also shown that, although the Moving Horizon Estimation (MHE provides greater robustness to a poor guess of the initial state, converging in less steps to the actual states, it is not justified for our examples due to the high additional computational effort.

  13. [Relationship among soil enzyme activities, vegetation state, and soil chemical properties of coal cinder yard].

    Science.gov (United States)

    Wang, Youbao; Zhang, Li; Liu, Dengyi

    2003-01-01

    From field investigation and laboratory analysis, the relationships among soil enzyme activities, vegetation state and soil chemical properties of coal cinder yard in thermal power station were studied. The results showed that vegetation on coal cinder yard was distributed in scattered patch mainly with single species of plant, and herbs were the dominant species. At the same time, the activity of three soil enzymes had a stronger relativity to environment conditions, such as vegetation state and soil chemical properties. The sensitivity of three soil enzymes to environmental stress was in order of urease > sucrase > catalase. The relativity of three soil enzymes to environmental factor was in order of sucrase > urease > catalase. Because of urease being the most susceptible enzyme to environmental conditions, and it was marked or utmost marked interrelated with vegetation state and soil chemical properties, urease activity could be used as an indicator for the reclamation of wasteland.

  14. State waste discharge permit application, 200-E chemical drain field

    Energy Technology Data Exchange (ETDEWEB)

    1994-06-01

    As part of the Hanford Federal Facility Agreement and Consent Order negotiations (Ecology et al. 1994), the US Department of Energy, Richland Operations Office, the US Environmental Protection Agency, and the Washington State Department of Ecology agreed that liquid effluent discharges to the ground on the Hanford Site which affect groundwater or have the potential to affect ground would be subject to permitting under the structure of Chapter 173-216 (or 173-218 where applicable) of the Washington Administrative Code, the State Waste Discharge Permit Program. As a result of this decision, the Washington State Department of Ecology and the US Department of Energy, Richland Operations Office entered into Consent Order No. DE 91NM-177, (Ecology and DOE-RL 1991). The Consent Order No. DE 91NM-177 requires a series of permitting activities for liquid effluent discharges. This document presents the State Waste Discharge Permit (SWDP) application for the 200-E Chemical Drain Field. Waste water from the 272-E Building enters the process sewer line directly through a floor drain, while waste water from the 2703-E Building is collected in two floor drains, (north and south) that act as sumps and are discharged periodically. The 272-E and 2703-E Buildings constitute the only discharges to the process sewer line and the 200-E Chemical Drain Field.

  15. Linear complexions: Confined chemical and structural states at dislocations.

    Science.gov (United States)

    Kuzmina, M; Herbig, M; Ponge, D; Sandlöbes, S; Raabe, D

    2015-09-04

    For 5000 years, metals have been mankind's most essential materials owing to their ductility and strength. Linear defects called dislocations carry atomic shear steps, enabling their formability. We report chemical and structural states confined at dislocations. In a body-centered cubic Fe-9 atomic percent Mn alloy, we found Mn segregation at dislocation cores during heating, followed by formation of face-centered cubic regions but no further growth. The regions are in equilibrium with the matrix and remain confined to the dislocation cores with coherent interfaces. The phenomenon resembles interface-stabilized structural states called complexions. A cubic meter of strained alloy contains up to a light year of dislocation length, suggesting that linear complexions could provide opportunities to nanostructure alloys via segregation and confined structural states.

  16. Structural simplification of chemical reaction networks in partial steady states.

    Science.gov (United States)

    Madelaine, Guillaume; Lhoussaine, Cédric; Niehren, Joachim; Tonello, Elisa

    2016-11-01

    We study the structural simplification of chemical reaction networks with partial steady state semantics assuming that the concentrations of some but not all species are constant. We present a simplification rule that can eliminate intermediate species that are in partial steady state, while preserving the dynamics of all other species. Our simplification rule can be applied to general reaction networks with some but few restrictions on the possible kinetic laws. We can also simplify reaction networks subject to conservation laws. We prove that our simplification rule is correct when applied to a module of a reaction network, as long as the partial steady state is assumed with respect to the complete network. Michaelis-Menten's simplification rule for enzymatic reactions falls out as a special case. We have implemented an algorithm that applies our simplification rules repeatedly and applied it to reaction networks from systems biology.

  17. VALIDATION GUIDELINES FOR LABORATORIES PERFORMING FORENSIC ANALYSIS OF CHEMICAL TERRORISM

    Science.gov (United States)

    The Scientific Working Group on Forensic Analysis of Chemical Terrorism (SWGFACT) has developed the following guidelines for laboratories engaged in the forensic analysis of chemical evidence associated with terrorism. This document provides a baseline framework and guidance for...

  18. Ni的化学态对甲烷部分氧化反应机理的影响:能学分析%Influence of Ni Chemical States on the Partial Oxidation Mechanism of Methane: An Energetics Analysis

    Institute of Scientific and Technical Information of China (English)

    夏文生; 常刚; 侯玉慧; 翁维正; 万惠霖

    2011-01-01

    采用键指数归一-平方势(UBI-QEP)法对不同化学态Ni上甲烷部分氧化反应中各可能基元步骤进行了能学计算研究.结果表明,反应的速度控制步骤与金属Ni的化学态有关.还原态Ni上CO形成的反应速度控制步骤为表面上CH3与O物种间的缔合,而带部分正电荷的Ni上CO形成的反应速度控制步骤则为甲烷氧助解离形成表面CHxO物种.还原态和带部分正电荷的Ni中心在表面上共存时,反应的速度控制步骤将取决于表面CH3形成与表面CH3、O物种缔合两反应间的竞争,其竞争的强弱涉及Ni的化学态.此外,反应活性中心向正电荷的Ni转化时,会导致表面C和O及H和H物种缔合的活化能显著降低,有利于CO、H2的形成,而表面CHx物种解离则变得不容易,表面积炭受到明显的抑制.%An energetics analysis of the possible elementary steps involved in the partial oxidation of methane (POM) over different chemical states of Ni was carried out using the unity bond index-quadratic exponential potential (UBI-QEP) method. The results show that the rate determining step for the partial oxidation mechanism of methane is related to the chemical state of the Ni. Over reduced Ni the rate determining step for CO formation is the association of surface CH3 species with surface O species. Over apartial positive charged Ni surface the rate determining step is that methane dissociates into the CHxO species with the assistance of oxygen. Over the reduced and partial positive charged Ni sites in coexistence, however, the rate determining step depends on the competition between the formation of surface CH3 species and the recombination of surface CH3 species with surface O species. This competition is related to the chemical states of the Ni sites. If the partial positive charged Ni sites are predominant on the surface, the recombination of surface C species with surface O species and the recombination of surface H atom species favor CO and H

  19. Solid-State NMR Studies of Chemically Lithiated CFx

    Science.gov (United States)

    Leifer, N. D.; Johnson, V. S.; Ben-Ari, R.; Gan, H.; Lehnes, J. M.; Guo, R.; Lu, W.; Muffoletto, B. C.; Reddy, T.; Stallworth, P. E.; Greenbaum, S. G.

    2010-01-01

    Three types of fluorinated carbon, all in their original form and upon sequential chemical lithiations via n-butyllithium, were investigated by 13C and 19F solid-state NMR methods. The three starting CFx materials [where x = 1 (nominally)] were fiber based, graphite based, and petroleum coke based. The aim of the current study was to identify, at the atomic/molecular structural level, factors that might account for differences in electrochemical performance among the different kinds of CFx. Differences were noted in the covalent F character among the starting compounds and in the details of LiF production among the lithiated samples. PMID:20676233

  20. LSENS - GENERAL CHEMICAL KINETICS AND SENSITIVITY ANALYSIS CODE

    Science.gov (United States)

    Bittker, D. A.

    1994-01-01

    which provides the relationships between the predictions of a kinetics model and the input parameters of the problem. LSENS provides for efficient and accurate chemical kinetics computations and includes sensitivity analysis for a variety of problems, including nonisothermal conditions. LSENS replaces the previous NASA general chemical kinetics codes GCKP and GCKP84. LSENS is designed for flexibility, convenience and computational efficiency. A variety of chemical reaction models can be considered. The models include static system, steady one-dimensional inviscid flow, reaction behind an incident shock wave including boundary layer correction, and the perfectly stirred (highly backmixed) reactor. In addition, computations of equilibrium properties can be performed for the following assigned states, enthalpy and pressure, temperature and pressure, internal energy and volume, and temperature and volume. For static problems LSENS computes sensitivity coefficients with respect to the initial values of the dependent variables and/or the three rates coefficient parameters of each chemical reaction. To integrate the ODEs describing chemical kinetics problems, LSENS uses the packaged code LSODE, the Livermore Solver for Ordinary Differential Equations, because it has been shown to be the most efficient and accurate code for solving such problems. The sensitivity analysis computations use the decoupled direct method, as implemented by Dunker and modified by Radhakrishnan. This method has shown greater efficiency and stability with equal or better accuracy than other methods of sensitivity analysis. LSENS is written in FORTRAN 77 with the exception of the NAMELIST extensions used for input. While this makes the code fairly machine independent, execution times on IBM PC compatibles would be unacceptable to most users. LSENS has been successfully implemented on a Sun4 running SunOS and a DEC VAX running VMS. With minor modifications, it should also be easily implemented on other

  1. Reacting gas mixtures in the state-to-state approach: The chemical reaction rates

    Energy Technology Data Exchange (ETDEWEB)

    Kustova, Elena V. [Department of Mathematics and Mechanics, Saint Petersburg State University, 198504 Universitetskiy pr., 28, Saint Petersburg (Russian Federation); Kremer, Gilberto M. [Departamento de Física, Universidade Federal do Paraná, Caixa Postal 19044, 81531-980 Curitiba (Brazil)

    2014-12-09

    In this work chemically reacting mixtures of viscous flows are analyzed within the framework of Boltzmann equation. By applying a modified Chapman-Enskog method to the system of Boltzmann equations general expressions for the rates of chemical reactions and vibrational energy transitions are determined as functions of two thermodynamic forces: the velocity divergence and the affinity. As an application chemically reacting mixtures of N{sub 2} across a shock wave are studied, where the first lowest vibrational states are taken into account. Here we consider only the contributions from the first four single quantum vibrational-translational energy transitions. It is shown that the contribution to the chemical reaction rate related to the affinity is much larger than that of the velocity divergence.

  2. Reacting gas mixtures in the state-to-state approach: The chemical reaction rates

    Science.gov (United States)

    Kustova, Elena V.; Kremer, Gilberto M.

    2014-12-01

    In this work chemically reacting mixtures of viscous flows are analyzed within the framework of Boltzmann equation. By applying a modified Chapman-Enskog method to the system of Boltzmann equations general expressions for the rates of chemical reactions and vibrational energy transitions are determined as functions of two thermodynamic forces: the velocity divergence and the affinity. As an application chemically reacting mixtures of N2 across a shock wave are studied, where the first lowest vibrational states are taken into account. Here we consider only the contributions from the first four single quantum vibrational-translational energy transitions. It is shown that the contribution to the chemical reaction rate related to the affinity is much larger than that of the velocity divergence.

  3. Systems analysis of past, present, and future chemical terrorism scenarios.

    Energy Technology Data Exchange (ETDEWEB)

    Hoette, Trisha Marie

    2012-03-01

    Throughout history, as new chemical threats arose, strategies for the defense against chemical attacks have also evolved. As a part of an Early Career Laboratory Directed Research and Development project, a systems analysis of past, present, and future chemical terrorism scenarios was performed to understand how the chemical threats and attack strategies change over time. For the analysis, the difficulty in executing chemical attack was evaluated within a framework of three major scenario elements. First, historical examples of chemical terrorism were examined to determine how the use of chemical threats, versus other weapons, contributed to the successful execution of the attack. Using the same framework, the future of chemical terrorism was assessed with respect to the impact of globalization and new technologies. Finally, the efficacy of the current defenses against contemporary chemical terrorism was considered briefly. The results of this analysis justify the need for continued diligence in chemical defense.

  4. Analysis of blood spots for polyfluoroalkyl chemicals

    Energy Technology Data Exchange (ETDEWEB)

    Kato, Kayoko; Wanigatunga, Amal A.; Needham, Larry L. [Division of Laboratory Sciences, National Center for Environmental Health, Centers for Disease Control and Prevention, Atlanta, GA (United States); Calafat, Antonia M., E-mail: acalafat@cdc.gov [Division of Laboratory Sciences, National Center for Environmental Health, Centers for Disease Control and Prevention, Atlanta, GA (United States)

    2009-12-10

    Polyfluoroalkyl chemicals (PFCs) have been detected in humans, in the environment, and in ecosystems around the world. The potential for developmental and reproductive toxicities of some PFCs is of concern especially to children's health. In the United States, a sample of a baby's blood, called a 'dried blood spot' (DBS), is obtained from a heel stick within 48 h of a child's birth. DBS could be useful for assessing prenatal exposure to PFCs. We developed a method based on online solid phase extraction coupled with high performance liquid chromatography-isotope dilution tandem mass spectrometry for measuring four PFCs in DBS, perfluorooctane sulfonate (PFOS), perfluorohexane sulfonate, perfluorooctanoate (PFOA), and perfluorononanoate. The analytical limits of detection using one whole DBS ({approx}75 {mu}L of blood) were <0.5 ng mL{sup -1}. To validate the method, we analyzed 98 DBS collected in May 2007 in the United States. PFOS and PFOA were detected in all DBS at concentrations in the low ng mL{sup -1} range. These data suggest that DBS may be a suitable matrix for assessing perinatal exposure to PFCs, but additional information related to sampling and specimen storage is needed to demonstrate the utility of these measures for assessing exposure.

  5. Chemical state of tellurium in a degraded LWR core

    Science.gov (United States)

    Imoto, S.; Tanabe, T.

    1988-06-01

    Changes of the chemical state of tellurium in the heatup stage of a severe fuel damage accident are estimated thermodynamically. According to equilibrium calculations with the SOLGASMIX-PV code, tellurium exists as cesium telluride, as the element or possibly as PdTe during normal operation. In the heatup stage of an accident, elemental tellurium is absorbed in the Zircaloy cladding by formation of ZrTe x ( x = 1-2). Cesium telluride does not react with Zr even under the low oxygen potentials favoring the {Zr}/{UO 2} reaction. Tellurium is also absorbed in oxygen-stabilized alpha-zirconium. The stability of Cs 2Te in the steam/hydrogen atmosphere is discussed.

  6. Zirconia-based solid state chemical gas sensors

    CERN Document Server

    Zhuiykov, S

    2000-01-01

    This paper presents an overview of chemical gas sensors, based on solid state technology, that are sensitive to environmental gases, such as O sub 2 , SO sub x , NO sub x , CO sub 2 and hydrocarbons. The paper is focussed on performance of electrochemical gas sensors that are based on zirconia as a solid electrolyte. The paper considers sensor structures and selection of electrode materials. Impact of interfaces on sensor performance is discussed. This paper also provides a brief overview of electrochemical properties of zirconia and their effect on sensor performance. Impact of auxiliary materials on sensors performance characteristics, such as sensitivity, selectivity, response time and recovery time, is also discussed. Dual gas sensors that can be applied for simultaneous monitoring of the concentration of both oxygen and other gas phase components, are briefly considered

  7. Chemically modified solid state nanopores for high throughput nanoparticle separation

    Energy Technology Data Exchange (ETDEWEB)

    Prabhu, Anmiv S; Kim, Min Jun [School of Biomedical Engineering and Health Science, Drexel University, Philadelphia, PA 19104 (United States); Jubery, Talukder Zaki N; Dutta, Prashanta [School of Mechanical and Materials Engineering, Washington State University, Pullman, WA 99164 (United States); Freedman, Kevin J; Mulero, Rafael, E-mail: mkim@coe.drexel.ed [Department of Mechanical Engineering and Mechanics, Drexel University, Philadelphia, PA 19104 (United States)

    2010-11-17

    The separation of biomolecules and other nanoparticles is a vital step in several analytical and diagnostic techniques. Towards this end we present a solid state nanopore-based set-up as an efficient separation platform. The translocation of charged particles through a nanopore was first modeled mathematically using the multi-ion model and the surface charge density of the nanopore membrane was identified as a critical parameter that determines the selectivity of the membrane and the throughput of the separation process. Drawing from these simulations a single 150 nm pore was fabricated in a 50 nm thick free-standing silicon nitride membrane by focused-ion-beam milling and was chemically modified with (3-aminopropyl)triethoxysilane to change its surface charge density. This chemically modified membrane was then used to separate 22 and 58 nm polystyrene nanoparticles in solution. Once optimized, this approach can readily be scaled up to nanopore arrays which would function as a key component of next-generation nanosieving systems.

  8. Chemical analysis of particles and semiconductor microstructures by synchrotron radiation soft x-rays photoemission spectromicroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Gozzo, F.; Triplett, B.; Fujimoto, H. [Intel Corp., Santa Clara, CA (United States). Dept. of Components Research] [and others

    1998-12-31

    Chemical analysis on a microscopic scale was performed on a TiN particle sample on silicon and on two patterned samples using a synchrotron source scanning photoemission microscope. For all the experiments, they exploit the ability, developed in the experimental system, to reach specific locations on the wafer and analyze the local chemical state.

  9. Testing fundamentals: The chemical state of geochemical tracers in biominerals.

    Science.gov (United States)

    Branson, O.; Redfern, S. A. T.; Read, E.; Elderfield, H.

    2015-12-01

    The use of many carbonate-derived geochemical proxies is underpinned by the assumption that tracer elements are incorporated 'ideally' as impurities the mineral lattice, following relatively straightforward kinetic and thermodynamic drives. This allows comparison to inorganic precipitation experiments, and provides a systematic starting point from which to translate geochemical tracers to environmental records. Biomineral carbonates are a prominent source of geochemical proxy material, and are far from an ideal inorganic system. They are structurally and compositionally heterogeneous mineral-organic composites, produced in tightly controlled biological environments, possibly via non-classical crystal growth mechanisms. Biominerals offer numerous opportunities for tracers to be incorporated in a 'non-ideal' state. For instance, tracers could be hosted within the organic component of the structure, in interstitial micro-domains of a separate mineral phase, or in localized high-impurity clusters. If a proxy element is hosted in a non-ideal state, our understanding of its incorporation and preservation is flawed, and the theoretical basis behind the proxies derived from it must be reevaluated. Thus far, the assumption of ideal tracer incorporation has remained largely untested, owing to the spatial resolution and sensitivity limits of available techniques. Developments in high-resolution, high-sensitivity X-ray spectroscopy at Scanning Transmission X-Ray Microscopes (STXMs) have allowed us to measure trace element coordination in foraminiferal calcite, at length-scales relevant to biomineralisation processes and tracer incorporation. This instrument has allowed us to test the fundamental assumptions behind several geochemical proxy elements. We present a summary of four STXM studies, assessing the chemical state and distribution of Mg (Branson et al, 2014), B (Branson et al, 2015), S and Na (unpub.), and highlight the implications of these data for the use of these

  10. Study of Cu-Inhibitor State for Post-Chemical Mechanical Polishing Cleaning

    Science.gov (United States)

    Harada, Ken; Ito, Atsushi; Kawase, Yasuhiro; Suzuki, Toshiyuki; Hara, Makoto; Sakae, Rina; Kimura, Chiharu; Aoki, Hidemitsu

    2011-05-01

    In order to reduce corrosion on the Cu surface in post-chemical mechanical polishing (CMP) cleaning, controlling the state of inhibitor layers is indispensable. In this study, to investigate the behavior of inhibitor layers in the cleaning process, Cu-benzotriazole (BTA) layers on CuOX were analyzed by electrochemical measurements and surface analysis. Electrochemical measurements revealed that Cu(I)-BTA can prevent corrosion more efficiently than Cu(II)-BTA, and surface analysis revealed that the Cu(I)-BTA layer is thin, whereas the Cu(II)-BTA layer is bulky. The Cu(I)-BTA layer is effective in preventing corrosion of the Cu surface.

  11. Accumulation and chemical states of radiocesium by fungus Saccharomyces cerevisiae

    Science.gov (United States)

    Ohnuki, Toshihiko; Sakamoto, Fuminori; Kozai, Naofumi; Yamasaki, Shinya; Yu, Qianqian

    2014-05-01

    After accident of Fukushima Daiichi Nuclear Power Plant, the fall-out radiocesium was deposited on the ground. Filamentous fungus is known to accumulate radiocesium in environment, even though many minerals are involved in soil. These facts suggest that fungus affect the migration behavior of radiocesium in the environment. However, accumulation mechanism of radiocesium by fungus is not understood. In the present study, accumulation and chemical states change of Cs by unicellular fungus of Saccharomyces cerevisiae have been studied to elucidate the role of microorganisms in the migration of radiocesium in the environment. Two different experimental conditions were employed; one is the accumulation experiments of radiocesium by S. cerevisiae from the agar medium containing 137Cs and a mineral of zeolite, vermiculite, smectite, mica, or illite. The other is the experiments using stable cesium to examine the chemical states change of Cs. In the former experiment, the cells were grown on membrane filter of 0.45 μm installed on the agar medium. After the grown cells were weighed, radioactivity in the cells was measured by an autoradiography technique. The mineral weight contents were changed from 0.1% to 1% of the medium. In the latter experiment, the cells were grown in the medium containing stable Cs between 1 mM and 10mM. The Cs accumulated cells were analyzed by SEM-EDS and EXAFS. The adsorption experiments of cesium by the cells under resting condition were also conducted to test the effect of cells metabolic activity. Without mineral in the medium, cells of S. cerevisiae accumulated 1.5x103 Bq/g from the medium containing 137Cs of 2.6x102 Bq/g. When mineral was added in the medium, concentration of 137Cs in the cells decreased. The concentration of 137Cs in the cells from the medium containing different minerals were in the following order; smectite, illite, mica > vermiculite > zeolite. This order was nearly the same as the inverse of distribution coefficient of

  12. Chemical States of Lanthanum in Carbonized La2O3-Mo Thermionic Cathode Materials

    Institute of Scientific and Technical Information of China (English)

    王金淑; 周美玲; 王亦曼; 张久兴; 聂祚仁; 左铁镛

    2003-01-01

    The chemical reaction between lanthanum oxide and molybdenum carbide was studied by thermodynamic calculation, thermal analysis and in-situ X-ray Photoelectron Spectroscopy. The theoretical results show that at the environment allowing for the evaporation of lanthanum, such as in high vacuum, La2O3 in the La2O3-Mo materials can be reduced to metallic lanthanum by molybdenum carbide (Mo2C). To confirm the conclusion, many analysis methods such as XRD, SPS, and TG-DTA were taken. The experimental results show that the chemical state of lanthanum changes during heating. It was proved, for the first time, that reacted metallic lanthanum appears at the surface of this kind of material at high temperature.

  13. Fourth-Order Vibrational Transition State Theory and Chemical Kinetics

    Science.gov (United States)

    Stanton, John F.; Matthews, Devin A.; Gong, Justin Z.

    2015-06-01

    Second-order vibrational perturbation theory (VPT2) is an enormously successful and well-established theory for treating anharmonic effects on the vibrational levels of semi-rigid molecules. Partially as a consequence of the fact that the theory is exact for the Morse potential (which provides an appropriate qualitative model for stretching anharmonicity), VPT2 calculations for such systems with appropriate ab initio potential functions tend to give fundamental and overtone levels that fall within a handful of wavenumbers of experimentally measured positions. As a consequence, the next non-vanishing level of perturbation theory -- VPT4 -- offers only slight improvements over VPT2 and is not practical for most calculations since it requires information about force constants up through sextic. However, VPT4 (as well as VPT2) can be used for other applications such as the next vibrational correction to rotational constants (the ``gammas'') and other spectroscopic parameters. In addition, the marriage of VPT with the semi-classical transition state theory of Miller (SCTST) has recently proven to be a powerful and accurate treatment for chemical kinetics. In this talk, VPT4-based SCTST tunneling probabilities and cumulative reaction probabilities are give for the first time for selected low-dimensional model systems. The prospects for VPT4, both practical and intrinsic, will also be discussed.

  14. Analysis, synthesis and design of chemical processes

    Energy Technology Data Exchange (ETDEWEB)

    Turton, R. [West Virginia Univ., Morgantown, WV (United States); Bailie, R.C.; Whiting, W.B.

    1998-12-31

    The book illustrates key concepts through a running example from the real world: the manufacture of benzene; covers design, economic considerations, troubleshooting and health/environmental safety; and includes exclusive software for estimating chemical manufacturing equipment capital costs. This book will help chemical engineers optimize the efficiency of production processes, by providing both a philosophical framework and detailed information about chemical process design. Design is the focal point of the chemical engineering practice. This book helps engineers and senior-level students hone their design skills through process design rather than simply plant design. It introduces all the basics of process simulation. Learn how to size equipment, optimize flowsheets, evaluate the economics of projects, and plan the operation of processes. Learn how to use Process Flow Diagrams; choose the operating conditions for a process; and evaluate the performance of existing processes and equipment. Finally, understand how chemical process design impacts health, safety, the environment and the community.

  15. Soft Sensor for Inputs and Parameters Using Nonlinear Singular State Observer in Chemical Processes

    Institute of Scientific and Technical Information of China (English)

    许锋; 汪晔晔; 罗雄麟

    2013-01-01

    Chemical processes are usually nonlinear singular systems. In this study, a soft sensor using nonlinear singular state observer is established for unknown inputs and uncertain model parameters in chemical processes, which are augmented as state variables. Based on the observability of the singular system, this paper presents a simplified observability criterion under certain conditions for unknown inputs and uncertain model parameters. When the observability is satisfied, the unknown inputs and the uncertain model parameters are estimated online by the soft sensor using augmented nonlinear singular state observer. The riser reactor of fluid catalytic cracking unit is used as an example for analysis and simulation. With the catalyst circulation rate as the only unknown input without model error, one temperature sensor at the riser reactor outlet will ensure the correct estimation for the catalyst cir-culation rate. However, when uncertain model parameters also exist, additional temperature sensors must be used to ensure correct estimation for unknown inputs and uncertain model parameters of chemical processes.

  16. Chemical Engineering Data Analysis Made Easy with DataFit

    Science.gov (United States)

    Brenner, James R.

    2006-01-01

    The outline for half of a one-credit-hour course in analysis of chemical engineering data is presented, along with a range of typical problems encountered later on in the chemical engineering curriculum that can be used to reinforce the data analysis skills learned in the course. This mini course allows students to be exposed to a variety of ChE…

  17. Quantum-chemical study of electronically excited states of protolytic forms of vanillic acid

    Science.gov (United States)

    Vusovich, O. V.; Tchaikovskaya, O. N.; Sokolova, I. V.; Vasil'eva, N. Y.

    2015-12-01

    The paper describes an analysis of possible ways of deactivation of electronically excited states of 4-hydroxy- 3-methoxy-benzoic acid (vanillic acid) and its protolytic forms with the use of quantum-chemical methods INDO/S (intermediate neglect of differential overlap with a spectroscopic parameterization) and MEP (molecular electrostatic potential). The ratio of radiative and non-radiative deactivation channels of the electronic excitation energy is established. The rate constants of photophysical processes (internal and intercombination conversions) occurring after the absorption of light in these forms are evaluated.

  18. Information-Theoretical Complexity Analysis of Selected Elementary Chemical Reactions

    Science.gov (United States)

    Molina-Espíritu, M.; Esquivel, R. O.; Dehesa, J. S.

    We investigate the complexity of selected elementary chemical reactions (namely, the hydrogenic-abstraction reaction and the identity SN2 exchange reaction) by means of the following single and composite information-theoretic measures: disequilibrium (D), exponential entropy(L), Fisher information (I), power entropy (J), I-D, D-L and I-J planes and Fisher-Shannon (FS) and Lopez-Mancini-Calbet (LMC) shape complexities. These quantities, which are functionals of the one-particle density, are computed in both position (r) and momentum (p) spaces. The analysis revealed that the chemically significant regions of these reactions can be identified through most of the single information-theoretic measures and the two-component planes, not only the ones which are commonly revealed by the energy, such as the reactant/product (R/P) and the transition state (TS), but also those that are not present in the energy profile such as the bond cleavage energy region (BCER), the bond breaking/forming regions (B-B/F) and the charge transfer process (CT). The analysis of the complexities shows that the energy profile of the abstraction reaction bears the same information-theoretical features of the LMC and FS measures, however for the identity SN2 exchange reaction does not hold a simple behavior with respect to the LMC and FS measures. Most of the chemical features of interest (BCER, B-B/F and CT) are only revealed when particular information-theoretic aspects of localizability (L or J), uniformity (D) and disorder (I) are considered.

  19. Current trends of the development of chemical analysis

    Directory of Open Access Journals (Sweden)

    Rema Matakova

    2014-12-01

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

  20. Chemical Diversity, Origin, and Analysis of Phycotoxins

    DEFF Research Database (Denmark)

    Rasmussen, Silas Anselm; Andersen, Aaron John Christian; Andersen, Nikolaj Gedsted;

    2016-01-01

    Microalgae, particularly those from the lineage Dinoflagellata, are very well-known for their ability to produce phycotoxins that may accumulate in the marine food chain and eventually cause poisoning in humans. This includes toxins accumulating in shellfish, such as saxitoxin, okadaic acid......, yessotoxins, azaspiracids, brevetoxins, and pinnatoxins. Other toxins, such as ciguatoxins and maitotoxins, accumulate in fish, where, as is the case for the latter compounds, they can be metabolized to even more toxic metabolites. On the other hand, much less is known about the chemical nature of compounds...... complex natural compounds known to mankind, with chemical structures that show no resemblance to what has been characterized from plants, fungi, or bacteria. In addition, it will summarize algal species known to be related to fish-killing blooms, but from which ichthyotoxins are yet to be characterized....

  1. Quantifying chemical reactions by using mixing analysis.

    Science.gov (United States)

    Jurado, Anna; Vázquez-Suñé, Enric; Carrera, Jesús; Tubau, Isabel; Pujades, Estanislao

    2015-01-01

    This work is motivated by a sound understanding of the chemical processes that affect the organic pollutants in an urban aquifer. We propose an approach to quantify such processes using mixing calculations. The methodology consists of the following steps: (1) identification of the recharge sources (end-members) and selection of the species (conservative and non-conservative) to be used, (2) identification of the chemical processes and (3) evaluation of mixing ratios including the chemical processes. This methodology has been applied in the Besòs River Delta (NE Barcelona, Spain), where the River Besòs is the main aquifer recharge source. A total number of 51 groundwater samples were collected from July 2007 to May 2010 during four field campaigns. Three river end-members were necessary to explain the temporal variability of the River Besòs: one river end-member is from the wet periods (W1) and two are from dry periods (D1 and D2). This methodology has proved to be useful not only to compute the mixing ratios but also to quantify processes such as calcite and magnesite dissolution, aerobic respiration and denitrification undergone at each observation point.

  2. Some Chemical and Electronic Considerations of Solid State Semiconductor Crystals.

    Science.gov (United States)

    Hinitz, Herman J.

    1986-01-01

    Describes the trend toward the use of electronic instrumentation to monitor and measure various parameters in chemical reactions. Stresses that a knowledge of the operational relationships involved in such instruments is essential for students beginning in science. Discusses electrostatic charges, semiconductor crystals, electronic conductors,…

  3. Tribology analysis of chemical-mechanical polishing

    Energy Technology Data Exchange (ETDEWEB)

    Runnels, S.R.; Eyman, L.M. (Sematech, Austin, TX (United States))

    1994-06-01

    To better understand the variation of material removal rate on a wafer during chemical-mechanical polishing (CMP), knowledge of the stress distribution on the wafer surface is required. The difference in wafer-surface stress distributions could be considerable depending on whether or not the wafer hydroplanes during polishing. This study analyzes the fluid film between the wafer and pad and demonstrates that hydroplaning is possible for standard CMP processes. The importance of wafer curvature, slurry viscosity, and rotation speed on the thickness of the fluid film is also demonstrated.

  4. State-Space Formulation for Circuit Analysis

    Science.gov (United States)

    Martinez-Marin, T.

    2010-01-01

    This paper presents a new state-space approach for temporal analysis of electrical circuits. The method systematically obtains the state-space formulation of nondegenerate linear networks without using concepts of topology. It employs nodal/mesh systematic analysis to reduce the number of undesired variables. This approach helps students to…

  5. Analytical solution of steady-state equations for chemical reaction networks with bilinear rate laws.

    Science.gov (United States)

    Halász, Adám M; Lai, Hong-Jian; McCabe Pryor, Meghan; Radhakrishnan, Krishnan; Edwards, Jeremy S

    2013-01-01

    True steady states are a rare occurrence in living organisms, yet their knowledge is essential for quasi-steady-state approximations, multistability analysis, and other important tools in the investigation of chemical reaction networks (CRN) used to describe molecular processes on the cellular level. Here, we present an approach that can provide closed form steady-state solutions to complex systems, resulting from CRN with binary reactions and mass-action rate laws. We map the nonlinear algebraic problem of finding steady states onto a linear problem in a higher-dimensional space. We show that the linearized version of the steady-state equations obeys the linear conservation laws of the original CRN. We identify two classes of problems for which complete, minimally parameterized solutions may be obtained using only the machinery of linear systems and a judicious choice of the variables used as free parameters. We exemplify our method, providing explicit formulae, on CRN describing signal initiation of two important types of RTK receptor-ligand systems, VEGF and EGF-ErbB1.

  6. CERENA: ChEmical REaction Network Analyzer--A Toolbox for the Simulation and Analysis of Stochastic Chemical Kinetics.

    Science.gov (United States)

    Kazeroonian, Atefeh; Fröhlich, Fabian; Raue, Andreas; Theis, Fabian J; Hasenauer, Jan

    2016-01-01

    Gene expression, signal transduction and many other cellular processes are subject to stochastic fluctuations. The analysis of these stochastic chemical kinetics is important for understanding cell-to-cell variability and its functional implications, but it is also challenging. A multitude of exact and approximate descriptions of stochastic chemical kinetics have been developed, however, tools to automatically generate the descriptions and compare their accuracy and computational efficiency are missing. In this manuscript we introduced CERENA, a toolbox for the analysis of stochastic chemical kinetics using Approximations of the Chemical Master Equation solution statistics. CERENA implements stochastic simulation algorithms and the finite state projection for microscopic descriptions of processes, the system size expansion and moment equations for meso- and macroscopic descriptions, as well as the novel conditional moment equations for a hybrid description. This unique collection of descriptions in a single toolbox facilitates the selection of appropriate modeling approaches. Unlike other software packages, the implementation of CERENA is completely general and allows, e.g., for time-dependent propensities and non-mass action kinetics. By providing SBML import, symbolic model generation and simulation using MEX-files, CERENA is user-friendly and computationally efficient. The availability of forward and adjoint sensitivity analyses allows for further studies such as parameter estimation and uncertainty analysis. The MATLAB code implementing CERENA is freely available from http://cerenadevelopers.github.io/CERENA/.

  7. Uncertainty analysis of EUSES: interviews with representatives from EU Member States and industry

    NARCIS (Netherlands)

    Jager T; ECO

    1998-01-01

    Ten representatives of the EU Member States and the chemical industry were interviewed to find out their views on applying uncertainty analysis to risk assessment of industrial chemicals. Although there was an interest expressed in this matter, uncertainty analysis was thought not to receive a high

  8. Disclosure of hydraulic fracturing fluid chemical additives: analysis of regulations.

    Science.gov (United States)

    Maule, Alexis L; Makey, Colleen M; Benson, Eugene B; Burrows, Isaac J; Scammell, Madeleine K

    2013-01-01

    Hydraulic fracturing is used to extract natural gas from shale formations. The process involves injecting into the ground fracturing fluids that contain thousands of gallons of chemical additives. Companies are not mandated by federal regulations to disclose the identities or quantities of chemicals used during hydraulic fracturing operations on private or public lands. States have begun to regulate hydraulic fracturing fluids by mandating chemical disclosure. These laws have shortcomings including nondisclosure of proprietary or "trade secret" mixtures, insufficient penalties for reporting inaccurate or incomplete information, and timelines that allow for after-the-fact reporting. These limitations leave lawmakers, regulators, public safety officers, and the public uninformed and ill-prepared to anticipate and respond to possible environmental and human health hazards associated with hydraulic fracturing fluids. We explore hydraulic fracturing exemptions from federal regulations, as well as current and future efforts to mandate chemical disclosure at the federal and state level.

  9. State Space Truncation with Quantified Errors for Accurate Solutions to Discrete Chemical Master Equation.

    Science.gov (United States)

    Cao, Youfang; Terebus, Anna; Liang, Jie

    2016-04-01

    The discrete chemical master equation (dCME) provides a general framework for studying stochasticity in mesoscopic reaction networks. Since its direct solution rapidly becomes intractable due to the increasing size of the state space, truncation of the state space is necessary for solving most dCMEs. It is therefore important to assess the consequences of state space truncations so errors can be quantified and minimized. Here we describe a novel method for state space truncation. By partitioning a reaction network into multiple molecular equivalence groups (MEGs), we truncate the state space by limiting the total molecular copy numbers in each MEG. We further describe a theoretical framework for analysis of the truncation error in the steady-state probability landscape using reflecting boundaries. By aggregating the state space based on the usage of a MEG and constructing an aggregated Markov process, we show that the truncation error of a MEG can be asymptotically bounded by the probability of states on the reflecting boundary of the MEG. Furthermore, truncating states of an arbitrary MEG will not undermine the estimated error of truncating any other MEGs. We then provide an overall error estimate for networks with multiple MEGs. To rapidly determine the appropriate size of an arbitrary MEG, we also introduce an a priori method to estimate the upper bound of its truncation error. This a priori estimate can be rapidly computed from reaction rates of the network, without the need of costly trial solutions of the dCME. As examples, we show results of applying our methods to the four stochastic networks of (1) the birth and death model, (2) the single gene expression model, (3) the genetic toggle switch model, and (4) the phage lambda bistable epigenetic switch model. We demonstrate how truncation errors and steady-state probability landscapes can be computed using different sizes of the MEG(s) and how the results validate our theories. Overall, the novel state space

  10. Pool chemical-associated health events in public and residential settings - United States, 2003-2012, and Minnesota, 2013.

    Science.gov (United States)

    Hlavsa, Michele C; Robinson, Trisha J; Collier, Sarah A; Beach, Michael J

    2014-05-16

    Pool chemicals are added to treated recreational water venues (e.g., pools, hot tubs/spas, and interactive fountains) primarily to protect public health by inactivating pathogens and maximizing the effectiveness of disinfection by controlling pH. However, pool chemicals also can cause injuries when handled or stored improperly. To estimate the number of emergency department (ED) visits for injuries associated with pool chemicals in the United States per year during 2003-2012, CDC analyzed data from the U.S. Consumer Product Safety Commission's National Electronic Injury Surveillance System (NEISS). This report summarizes the results of that analysis. In 2012 alone, an estimated 4,876 persons (95% confidence interval [CI] = 2,821-6,930) visited an ED for injuries associated with pool chemicals. Almost half of the patients were aged pool chemical-associated health event that occurred in Minnesota in 2013, which sent seven children and one adult to an ED. An investigation by the Minnesota Department of Health (MDH) determined the cause to be poor monitoring of or response to pool chemistry. Pool chemical-associated health events are preventable. CDC's Model Aquatic Health Code (MAHC) (1) is a resource that state and local agencies can use to optimize prevention of injuries and illnesses associated with public treated recreational water venues, including pool chemical-associated health events.

  11. Chemical reaction rates and non-equilibrium pressure of reacting gas mixtures in the state-to-state approach

    Energy Technology Data Exchange (ETDEWEB)

    Kustova, Elena V., E-mail: e.kustova@spbu.ru [Department of Mathematics and Mechanics, Saint Petersburg State University, 198504 Universitetskiy pr. 28, Saint Petersburg (Russian Federation); Kremer, Gilberto M., E-mail: kremer@fisica.ufpr.br [Departamento de Física, Universidade Federal do Paraná, Caixa Postal 19044, 81531-980 Curitiba (Brazil)

    2014-12-05

    Highlights: • State-to-state approach for coupled vibrational relaxation and chemical reactions. • Self-consistent model for rates of non-equilibrium reactions and energy transitions. • In viscous flows mass action law is violated. • Cross coupling between reaction rates and non-equilibrium pressure in viscous flow. • Results allow implementing the state-to-state approach for viscous flow simulations. - Abstract: Viscous gas flows with vibrational relaxation and chemical reactions in the state-to-state approach are analyzed. A modified Chapman–Enskog method is used for the determination of chemical reaction and vibrational transition rates and non-equilibrium pressure. Constitutive equations depend on the thermodynamic forces: velocity divergence and chemical reaction/transition affinity. As an application, N{sub 2} flow with vibrational relaxation across a shock wave is investigated. Two distinct processes occur behind the shock: for small values of the distance the affinity is large and vibrational relaxation is in its initial stage; for large distances the affinity is small and the chemical reaction is in its final stage. The affinity contributes more to the transition rate than the velocity divergence and the effect of these two contributions are more important for small distances from the shock front. For the non-equilibrium pressure, the term associated with the bulk viscosity increases by a small amount the hydrostatic pressure.

  12. Synthesis of high surface area nanometer magnesia by solid-state chemical reaction

    Institute of Scientific and Technical Information of China (English)

    GUAN Hongbo; WANG Pei; ZHAO Biying; ZHU Yuexiang; XIE Youchang

    2007-01-01

    Nanometer MgO samples with high surface area,small crystal size and mesoporous texture were synthesized tion process accelerated the sintering of MgO,and MgO with calcining its precursor in flowing dry nitrogen at 520℃ for 4 h.The samples were characterized by X-ray diffraction,N2 adsorption,transmission electron microscopy,thermogravimetry,and differential thermal analysis.The as-prepared MgO was composed of nanocrystals with a size of about 4-5 nm and formed a wormhole-like porous structure.The MgO also had good thermal stability,and its surface areas remained at 357 and 153 m2.g-1 after calcination at 600 and 800℃ for 2 h,respectively.Compared with the MgO sample prepared by the precipitation method,MgO prepared by solid-state chemical reaction has uniform pore size distribution,surface area,and crystal size.The solid-state chemical method has the advantages of low cost,low pollution,and high yield,therefore it appears to be a promising method in the industrial manufacture of nanometer MgO.

  13. Occupational chemical exposures and congenital anomalies: state of the art

    Energy Technology Data Exchange (ETDEWEB)

    Cordier, S. (Centre de Lutte Contre le Cancer Gustave-Roussy, 94 - Villejuif (France)); Goujard, J. (Maternite Baudelocque, 75 - Paris (France))

    1994-01-01

    Several thousands of compounds with a potential reproductive toxicity have been identified in animals, some of them are teratogens. In humans, only a small number of chemicals, administered as drugs, present in the diet, or in the occupational environment are recognized human teratogens. In parallel, about 60% of congenital anomalies have no identified cause and most probably some compounds present in the environment may contribute to certain anomalies. This paper presents a review of published epidemiological studies on the association between occupational exposures and congenital anomalies, focusing more particularly on some groups of compounds or some occupations such as: anaesthetic gases, laboratory work, solvents, pesticides and lead. (authors).

  14. Experimental and Quantum-Chemical Study of Electronically Excited States of Protolytic Isovanillin Species

    Science.gov (United States)

    Vusovich, O. V.; Tchaikovskaya, O. N.; Sokolova, I. V.; Vasil'eva, N. Yu.

    2014-05-01

    Methods of electronic spectroscopy and quantum chemistry are used to compare protolytic vanillin and isovanillin species. Three protolytic species: anion, cation, and neutral are distinguished in the ground state of the examined molecules. Vanillin and isovanillin in the ground state in water possess identical spectral characteristics: line positions and intensities in the absorption spectra coincide. Minima of the electrostatic potential demonstrate that the deepest isomer minimum is observed on the carbonyl oxygen atom. However, investigations of the fluorescence spectra show that the radiative properties of isomers differ. An analysis of results of quantum-chemical calculations demonstrate that the long-wavelength ππ* transition in the vanillin absorption spectra is formed due to electron charge transfer from the phenol part of the molecule to oxygen atoms of the methoxy and carbonyl groups, and in the isovanillin absorption spectra, it is formed only on the oxygen atom of the methoxy group. The presence of hydroxyl and carbonyl groups in the structure of the examined molecules leads to the fact that isovanillin in the ground S0 state, the same as vanillin, possesses acidic properties, whereas in the excited S1 state, they possess basic properties. A comparison of the рKа values of aqueous solutions demonstrates that vanillin possesses stronger acidic and basic properties in comparison with isovanillin.

  15. Chemical reaction rates and non-equilibrium pressure of reacting gas mixtures in the state-to-state approach

    Science.gov (United States)

    Kustova, Elena V.; Kremer, Gilberto M.

    2014-12-01

    Viscous gas flows with vibrational relaxation and chemical reactions in the state-to-state approach are analyzed. A modified Chapman-Enskog method is used for the determination of chemical reaction and vibrational transition rates and non-equilibrium pressure. Constitutive equations depend on the thermodynamic forces: velocity divergence and chemical reaction/transition affinity. As an application, N2 flow with vibrational relaxation across a shock wave is investigated. Two distinct processes occur behind the shock: for small values of the distance the affinity is large and vibrational relaxation is in its initial stage; for large distances the affinity is small and the chemical reaction is in its final stage. The affinity contributes more to the transition rate than the velocity divergence and the effect of these two contributions are more important for small distances from the shock front. For the non-equilibrium pressure, the term associated with the bulk viscosity increases by a small amount the hydrostatic pressure.

  16. Cyanobactins from Cyanobacteria: Current Genetic and Chemical State of Knowledge

    Directory of Open Access Journals (Sweden)

    Joana Martins

    2015-11-01

    Full Text Available Cyanobacteria are considered to be one of the most promising sources of new, natural products. Apart from non-ribosomal peptides and polyketides, ribosomally synthesized and post-translationally modified peptides (RiPPs are one of the leading groups of bioactive compounds produced by cyanobacteria. Among these, cyanobactins have sparked attention due to their interesting bioactivities and for their potential to be prospective candidates in the development of drugs. It is assumed that the primary source of cyanobactins is cyanobacteria, although these compounds have also been isolated from marine animals such as ascidians, sponges and mollusks. The aim of this review is to update the current knowledge of cyanobactins, recognized as being produced by cyanobacteria, and to emphasize their genetic clusters and chemical structures as well as their bioactivities, ecological roles and biotechnological potential.

  17. Cyanobactins from Cyanobacteria: Current Genetic and Chemical State of Knowledge.

    Science.gov (United States)

    Martins, Joana; Vasconcelos, Vitor

    2015-11-13

    Cyanobacteria are considered to be one of the most promising sources of new, natural products. Apart from non-ribosomal peptides and polyketides, ribosomally synthesized and post-translationally modified peptides (RiPPs) are one of the leading groups of bioactive compounds produced by cyanobacteria. Among these, cyanobactins have sparked attention due to their interesting bioactivities and for their potential to be prospective candidates in the development of drugs. It is assumed that the primary source of cyanobactins is cyanobacteria, although these compounds have also been isolated from marine animals such as ascidians, sponges and mollusks. The aim of this review is to update the current knowledge of cyanobactins, recognized as being produced by cyanobacteria, and to emphasize their genetic clusters and chemical structures as well as their bioactivities, ecological roles and biotechnological potential.

  18. Surface chemical composition analysis of heat-treated bamboo

    Energy Technology Data Exchange (ETDEWEB)

    Meng, Fan-dan, E-mail: fandan_meng@163.com [MOE Key Laboratory of Wooden Material Science and Application, Beijing Forestry University, 35 Qinghua East Road, Haidian District, Beijing 100083 (China); Yu, Yang-lun, E-mail: yuyanglun@caf.ac.cn [Research Institute of Wood Industry, Chinese Academy of Forestry, No 1 Dongxiaofu, Haidian District, Beijing 100091 (China); Zhang, Ya-mei, E-mail: zhangyamei@caf.ac.cn [Research Institute of Wood Industry, Chinese Academy of Forestry, No 1 Dongxiaofu, Haidian District, Beijing 100091 (China); Yu, Wen-ji, E-mail: yuwenji@caf.ac.cn [Research Institute of Wood Industry, Chinese Academy of Forestry, No 1 Dongxiaofu, Haidian District, Beijing 100091 (China); Gao, Jian-min, E-mail: gaojm@bjfu.edu.cn [MOE Key Laboratory of Wooden Material Science and Application, Beijing Forestry University, 35 Qinghua East Road, Haidian District, Beijing 100083 (China)

    2016-05-15

    Highlights: • Investigate the detailed chemical components contents change of bamboo due to heating. • Chemical analysis of bamboo main components during heating. • Identify the connection between the oxygen to carbon atomic ratio changes and chemical degradation. - Abstract: In this study, the effect of heat treatment on the chemical composition of bamboo slivers was studied. The chemical properties of the samples were examined by chemical analysis. Results showed a decrease in the contents of holocellulose and α-cellulose, as well as an increase in the contents of lignin and extractives. Changes in the chemical structure of bamboo components were analyzed by Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). FTIR spectroscopy results indicated that hemicellulose contents decrease, whereas lignin contents increase after heat treatment. Ester formation linked to lignin decreased the hygroscopicity of the bamboo samples and consequently improved their dimensional stability and durability. XPS spectroscopy results showed that hemicelluloses and celluloses are relatively more sensitive to the heating process than lignin. As a consequence, hemicellulose and cellulose contents decreased, whereas lignin contents increased during heat treatment. The results obtained in this study provide useful information for the future utilization of heat-treated bamboo.

  19. A UML Profile for State Analysis

    Science.gov (United States)

    Murray, Alex; Rasmussen, Robert

    2010-01-01

    State Analysis is a systems engineering methodology for the specification and design of control systems, developed at the Jet Propulsion Laboratory. The methodology emphasizes an analysis of the system under control in terms of States and their properties and behaviors and their effects on each other, a clear separation of the control system from the controlled system, cognizance in the control system of the controlled system's State, goal-based control built on constraining the controlled system's States, and disciplined techniques for State discovery and characterization. State Analysis (SA) introduces two key diagram types: State Effects and Goal Network diagrams. The team at JPL developed a tool for performing State Analysis. The tool includes a drawing capability, backed by a database that supports the diagram types and the organization of the elements of the SA models. But the tool does not support the usual activities of software engineering and design - a disadvantage, since systems to which State Analysis can be applied tend to be very software-intensive. This motivated the work described in this paper: the development of a preliminary Unified Modeling Language (UML) profile for State Analysis. Having this profile would enable systems engineers to specify a system using the methods and graphical language of State Analysis, which is easily linked with a larger system model in SysML (Systems Modeling Language), while also giving software engineers engaged in implementing the specified control system immediate access to and use of the SA model, in the same language, UML, used for other software design. That is, a State Analysis profile would serve as a shared modeling bridge between system and software models for the behavior aspects of the system. This paper begins with an overview of State Analysis and its underpinnings, followed by an overview of the mapping of SA constructs to the UML metamodel. It then delves into the details of these mappings and the

  20. Analysis of Joint Ventures Financial State

    Directory of Open Access Journals (Sweden)

    Alla V. Dmitrenko

    2013-01-01

    Full Text Available The article describes the basic techniques for the analysis of businesses financial state and methods that were adapted for the joint ventures activities, analyses joint venture financial state, makes conclusions and submits reasonable proposals for improvement of its future activities

  1. Characterization of Chemical Suicides in the United States and Its Adverse Impact on Responders and Bystanders

    Directory of Open Access Journals (Sweden)

    Ayana R. Anderson

    2016-11-01

    Full Text Available Introduction: A suicide trend that involves mixing household chemicals to produce hydrogen sulfide or hydrogen cyanide, commonly referred to as a detergent, hydrogen sulfide, or chemical suicide is a continuing problem in the United States (U.S.. Because there is not one database responsible for tracking chemical suicides, the actual number of incidents in the U.S. is unknown. To prevent morbidity and mortality associated with chemical suicides, it is important to characterize the incidents that have occurred in the U.S. Methods: The author analyzed data from 2011-2013 from state health departments participating in the Agency for Toxic Substances and Disease Registry’s National Toxic Substance Incidents Program (NTSIP. NTSIP is a web-based chemical incident surveillance system that tracks the public health consequences (e.g., morbidity, mortality from acute chemical releases. Reporting sources for NTSIP incidents typically include first responders, hospitals, state environmental agencies, and media outlets. To find chemical suicide incidents in NTSIP’s database, the author queried open text fields in the comment, synopsis, and contributing factors variables for potential incidents. Results: Five of the nine states participating in NTSIP reported a total of 22 chemical suicide incidents or attempted suicides during 2011-2013. These states reported a total of 43 victims: 15 suicide victims who died, seven people who attempted suicide but survived, eight responders, and four employees working at a coroner’s office; the remainder were members of the general public. None of the injured responders reported receiving HazMat technician-level training, and none had documented appropriate personal protective equipment. Conclusion: Chemical suicides produce lethal gases that can pose a threat to responders and bystanders. Describing the characteristics of these incidents can help raise awareness among responders and the public about the dangers of

  2. Arrays in biological and chemical analysis

    DEFF Research Database (Denmark)

    Christensen, Claus Bo Vöge

    2002-01-01

    Recently a dramatic change has happened for biological and biochemical analysis. Originally developed as an academic massive parallel screening tool, industry has caught the idea as well of performing all kinds of assays in the new format of microarrays. From food manufacturers over water supply...... plants to the omnipresent pharmaceutical industry, the buzz-word is bioarrays, attracting scientific funding and investor capital. Although only few commercial products are currently out in the research laboratorium, hospital clinic or at the local doctor, there are high expectations for arrays screening...... predispositions and following therapy, monitoring the amount of bacteria in food stuff, measuring the small signs from cardiac arrest before it happens, analysing the toxin level in a water sample (preferentially on-line) or deciphering the identity of an infecting bug. (C) 2002 Elsevier Science B.V. All rights...

  3. Appendix C. Collection of Samples for Chemical Agent Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Koester, C; Thompson, C; Doerr, T; Scripsick, R

    2005-09-23

    This chapter describes procedures for the collection and analysis of samples of various matrices for the purpose of determining the presence of chemical agents in a civilian setting. This appendix is intended to provide the reader with sufficient information to make informed decisions about the sampling and analysis process and to suggest analytical strategies that might be implemented by the scientists performing sampling and analysis. This appendix is not intended to be used as a standard operating procedure to provide detailed instructions as to how trained scientists should handle samples. Chemical agents can be classified by their physical and chemical properties. Table 1 lists the chemical agents considered by this report. In selecting sampling and analysis methods, we have considered procedures proposed by the Organization for Prohibition of Chemical Weapons (OPCW), the U. S. Environmental Protection Agency (EPA), and peer-reviewed scientific literature. EPA analytical methods are good resources describing issues of quality assurance with respect to chain-of-custody, sample handling, and quality control requirements.

  4. Black tea: chemical analysis and stability.

    Science.gov (United States)

    Li, Shiming; Lo, Chih-Yu; Pan, Min-Hsiung; Lai, Ching-Shu; Ho, Chi-Tang

    2013-01-01

    Tea is the most popular flavored and functional drink worldwide. The nutritional value of tea is mostly from the tea polyphenols that are reported to possess a broad spectrum of biological activities, including anti-oxidant properties, reduction of various cancers, inhibition of inflammation, and protective effects against diabetes, hyperlipidemia and obesity. Tea polyphenols include catechins and gallic acid in green and white teas, and theaflavins and thearubigins as well as other catechin polymers in black and oolong teas. Accurate analysis of black tea polyphenols plays a significant role in the identification of black tea contents, quality control of commercial tea beverages and extracts, differentiation of various contents of theaflavins and catechins and correlations of black tea identity and quality with biological activity, and most importantly, the establishment of the relationship between quantitative tea polyphenol content and its efficacy in animal or human studies. Global research in tea polyphenols has generated much in vitro and in vivo data rationally correlating tea polyphenols with their preventive and therapeutic properties in human diseases such as cancer, and metabolic and cardiovascular diseases etc. Based on these scientific findings, numerous tea products have been developed including flavored tea drinks, tea-based functional drinks, tea extracts and concentrates, and dietary supplements and food ingredients, demonstrating the broad applications of tea and its extracts, particularly in the field of functional food.

  5. Spectroscopic and quantum chemical analysis of Isonicotinic acid methyl ester

    Science.gov (United States)

    Shoba, D.; Periandy, S.; Govindarajan, M.; Gayathri, P.

    2015-02-01

    In this present study, an organic compound Isonicotinic acid methyl ester (INAME) was structurally characterized by FTIR, FT-Raman, and NMR and UV spectroscopy. The optimized geometrical parameters and energies of all different and possible conformers of INAME are obtained from Density Functional Theory (DFT) by B3LYP/6-311++G(d,p) method. There are three conformers (SI, SII-1, and SII-2) for this molecule (ground state). The most stable conformer of INAME is SI conformer. The molecular geometry and vibrational frequencies of INAME in the ground state have been calculated by using HF and density functional method (B3LYP) 6-311++G (d,p) basis set. Detailed vibrational spectral analysis has been carried out and assignments of the observed fundamental bands have been proposed on the basis of peak positions and relative intensities. The computed vibrational frequencies were compared with the experimental frequencies, which yield good agreement between observed and calculated frequencies. A study on the electronic properties, such as HOMO and LUMO energies were performed by time independent DFT approach. Besides, molecular electrostatic potential (MEP) and thermodynamic properties were performed. The electric dipole moment (μ) and first hyper polarizability (β) values of the investigated molecule were computed using ab initio quantum mechanical calculations. The calculated results show that the INAME molecule may have microscopic nonlinear optical (NLO) behavior with non zero values. The 1H and 13C nuclear magnetic resonance (NMR) chemical shifts of the molecule were calculated by gauge independent atomic orbital (GIAO) method.

  6. A review of chemical gradient systems for cell analysis.

    Science.gov (United States)

    Somaweera, Himali; Ibraguimov, Akif; Pappas, Dimitri

    2016-02-11

    Microfluidic spatial and temporal gradient generators have played an important role in many biological assays such as in the analysis of wound healing, inflammation, and cancer metastasis. Chemical gradient systems can also be applied to other fields such as drug design, chemical synthesis, chemotaxis, etc. Microfluidic systems are particularly amenable to gradient formation, as the length scales used in chips enable fluid processes that cannot be conducted in bulk scale. In this review we discuss new microfluidic devices for gradient generation and applications of those systems in cell analysis.

  7. Chemical climatology of the southeastern United States, 1999-2013

    Science.gov (United States)

    Hidy, G. M.; Blanchard, C. L.; Baumann, K.; Edgerton, E.; Tanenbaum, S.; Shaw, S.; Knipping, E.; Tombach, I.; Jansen, J.; Walters, J.

    2014-11-01

    A series of experiments (the Southern Oxidant and Aerosol Study - SOAS) took place in central Alabama in June-July, 2013 as part of the broader Southern Atmosphere Study (SAS). These projects were aimed at studying oxidant photochemistry and formation and impacts of aerosols at a detailed process level in a location where high biogenic organic vapor emissions interact with anthropogenic emissions, and the atmospheric chemistry occurs in a subtropical climate in North America. The majority of the ground-based experiments were located at the Southeastern Aerosol Research and Characterization (SEARCH) Centreville (CTR) site near Brent, Alabama, where extensive, unique aerometric measurements of trace gases and particles and meteorology were made beginning in the early 1990s through 2013. The SEARCH network data permits a characterization of the temporal and spatial context of the SOAS findings. Our earlier analyses of emissions and air quality trends are extended through 2013 to provide a perspective for continued decline in ambient concentrations, and the implications of these changes to regional sulfur oxide, nitrogen-ozone, and carbon chemistry. The narrative supports the SAS program in terms of long-term average chemistry (chemical climatology) and short-term comparisons of early summer average spatial variability across the southeastern US at high temporal (hourly) resolution. The long-term measurements show that the SOAS experiments took place during the second wettest and coolest year in the 2000-2013 period, with lower than average solar radiation. The pollution levels at CTR and other SEARCH sites were the lowest since full measurements began in 1999. Changes in anthropogenic gas and particle emissions between 1999 and 2013 account for the decline in pollutant concentrations at the monitoring sites in the region. The data provide an opportunity to contrast SOAS results with temporally and spatially variable conditions in support of the development of tests

  8. Chemical climatology of the southeastern United States, 1999–2013

    Directory of Open Access Journals (Sweden)

    G. M. Hidy

    2014-06-01

    Full Text Available A series of experiments (the Southern Oxidant and Aerosol Study-SOAS took place in central Alabama in June–July 2013 as part of the broader Southern Atmosphere Study (SAS. These projects were aimed at studying oxidant photochemistry and formation and impacts of aerosols at a detailed process level in a location where high biogenic organic vapor emissions interact with anthropogenic emissions, and the atmospheric chemistry occurs in a subtropical climate in North America. The majority of the ground-based experiments were located at the Southeastern Aerosol Research and Characterization (SEARCH Centreville (CTR site near Brent, Alabama, where extensive, unique aerometric measurements of meteorology, trace gases and particles have been made from the early 1990s through 2013. The SEARCH network data permits a characterization of temporal and spatial context of the SOAS findings. The long-term measurements show that the SOAS experiments took place during the second wettest and coolest year in the 2000–2013 period, with lower than average solar radiation. The pollution levels at CTR and other SEARCH sites were the lowest since full measurements began in 1999. This dataset provides a perspective for the SOAS program in terms of long-term average chemistry (chemical climatology and short-term comparisons of summer average spatial variability across the Southeast at high temporal (hourly resolution. Changes in anthropogenic gas and particle emissions between 1999 and 2013, account for the decline in pollutant concentrations at the monitoring sites in the region. The long-term and short-term data provide an opportunity to contrast SOAS results with temporally and spatially variable conditions in support for the development of tests for the robustness of SOAS findings.

  9. ANALYSIS OF SAMPLES FROM TANK 5F CHEMICAL CLEANING

    Energy Technology Data Exchange (ETDEWEB)

    Poirier, M.; Fink, S.

    2011-03-07

    The Savannah River Site (SRS) is preparing Tank 5F for closure. The first step in preparing the tank for closure is mechanical sludge removal. Following mechanical sludge removal, SRS performed chemical cleaning with oxalic acid to remove the sludge heel. Personnel are currently assessing the effectiveness of the chemical cleaning. SRS personnel collected liquid samples during chemical cleaning and submitted them to Savannah River National Laboratory (SRNL) for analysis. Following chemical cleaning, they collected a solid sample (also known as 'process sample') and submitted it to SRNL for analysis. The authors analyzed these samples to assess the effectiveness of the chemical cleaning process. The conclusions from this work are: (1) With the exception of iron, the dissolution of sludge components from Tank 5F agreed with results from the actual waste demonstration performed in 2007. The fraction of iron removed from Tank 5F by chemical cleaning was significantly less than the fraction removed in the SRNL demonstrations. The likely cause of this difference is the high pH following the first oxalic acid strike. (2) Most of the sludge mass remaining in the tank is iron and nickel. (3) The remaining sludge contains approximately 26 kg of barium, 37 kg of chromium, and 37 kg of mercury. (4) Most of the radioactivity remaining in the residual material is beta emitters and {sup 90}Sr. (5) The chemical cleaning removed more than {approx} 90% of the uranium isotopes and {sup 137}Cs. (6) The chemical cleaning removed {approx} 70% of the neptunium, {approx} 83% of the {sup 90}Sr, and {approx} 21% of the {sup 60}Co. (7) The chemical cleaning removed less than 10% of the plutonium, americium, and curium isotopes. (8) The chemical cleaning removed more than 90% of the aluminium, calcium, and sodium from the tank. (9) The cleaning operations removed 61% of lithium, 88% of non-radioactive strontium, and 65% of zirconium. The {sup 90}Sr and non-radioactive strontium were

  10. Surface chemical composition analysis of heat-treated bamboo

    Science.gov (United States)

    Meng, Fan-dan; Yu, Yang-lun; Zhang, Ya-mei; Yu, Wen-ji; Gao, Jian-min

    2016-05-01

    In this study, the effect of heat treatment on the chemical composition of bamboo slivers was studied. The chemical properties of the samples were examined by chemical analysis. Results showed a decrease in the contents of holocellulose and α-cellulose, as well as an increase in the contents of lignin and extractives. Changes in the chemical structure of bamboo components were analyzed by Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). FTIR spectroscopy results indicated that hemicellulose contents decrease, whereas lignin contents increase after heat treatment. Ester formation linked to lignin decreased the hygroscopicity of the bamboo samples and consequently improved their dimensional stability and durability. XPS spectroscopy results showed that hemicelluloses and celluloses are relatively more sensitive to the heating process than lignin. As a consequence, hemicellulose and cellulose contents decreased, whereas lignin contents increased during heat treatment. The results obtained in this study provide useful information for the future utilization of heat-treated bamboo.

  11. Gradient Bundle Analysis: A Full Topological Approach to Chemical Bonding

    CERN Document Server

    Morgenstern, Amanda

    2016-01-01

    The "chemical bond" is a central concept in molecular sciences, but there is no consensus as to what a bond actually is. Therefore, a variety of bonding models have been developed, each defining the structure of molecules in a different manner with the goal of explaining and predicting chemical properties. This thesis describes the initial development of gradient bundle analysis (GBA), a chemical bonding model that creates a high resolution picture of chemical interactions within the charge density framework. GBA is based on concepts from the quantum theory of atoms in molecules (QTAIM), but uses a more complete picture of the topology and geometry of the electron charge density to understand and predict bonding interactions. Gradient bundles are defined as volumes bounded by zero-flux surfaces (ZFSs) in the gradient of the charge density with well-defined energies. The structure of gradient bundles provides an avenue for detecting the locations of valence electrons, which correspond to reactive regions in a ...

  12. Steady-state properties of a finite system driven by a chemical-potential gradient

    DEFF Research Database (Denmark)

    Andersen, Jørgen Vitting; Mouritsen, Ole G.

    1990-01-01

    A two-dimensional lattice-gas model with repulsive interactions periodically infinite in one dimension and finite in the other is driven into a mass-transporting steady state by asymmetric chemical potentials applied at the open edges. By computer-simulation techniques the steady-state current...

  13. Computational singular perturbation analysis of stochastic chemical systems with stiffness

    Science.gov (United States)

    Wang, Lijin; Han, Xiaoying; Cao, Yanzhao; Najm, Habib N.

    2017-04-01

    Computational singular perturbation (CSP) is a useful method for analysis, reduction, and time integration of stiff ordinary differential equation systems. It has found dominant utility, in particular, in chemical reaction systems with a large range of time scales at continuum and deterministic level. On the other hand, CSP is not directly applicable to chemical reaction systems at micro or meso-scale, where stochasticity plays an non-negligible role and thus has to be taken into account. In this work we develop a novel stochastic computational singular perturbation (SCSP) analysis and time integration framework, and associated algorithm, that can be used to not only construct accurately and efficiently the numerical solutions to stiff stochastic chemical reaction systems, but also analyze the dynamics of the reduced stochastic reaction systems. The algorithm is illustrated by an application to a benchmark stochastic differential equation model, and numerical experiments are carried out to demonstrate the effectiveness of the construction.

  14. Chemical analysis of Ginkgo biloba leaves and extracts

    NARCIS (Netherlands)

    Beek, van T.A.

    2002-01-01

    The chemical analysis and quality control of Ginkgo leaves and extracts is reviewed. Important constituents present in the medicinally used leaves are the terpene trilactones, i.e., ginkgolides A, B, C, J and bilobalide, many flavonol glycosides, biflavones, proanthocyanidins, alkylphenols, simple p

  15. Spectangular - Spectral Disentangling For Detailed Chemical Analysis Of Binaries

    Science.gov (United States)

    Sablowski, Daniel

    2016-08-01

    Disentangling of spectra helps to improve the orbit parameters and allows detailed chemical analysis. Spectangular is a GUI program written in C++ for spectral disentangling of spectra of SB1 and SB2 systems. It is based on singular value decomposition in the wavelength space and is coupled to an orbital solution.The results are the component spectra and the orbital parameters.

  16. Forensic analysis of bicomponent fibers using infrared chemical imaging.

    Science.gov (United States)

    Flynn, Katherine; O'Leary, Robyn; Roux, Claude; Reedy, Brian J

    2006-05-01

    The application of infrared chemical imaging to the analysis of bicomponent fibers was evaluated. Eleven nominally bicomponent fibers were examined either side-on or in cross-section. In six of the 11 samples, infrared chemical imaging was able to spatially resolve two spectroscopically distinct regions when the fibers were examined side-on. As well as yielding characteristic infrared spectra of each component, the technique also provided images that clearly illustrated the side-by-side configuration of these components in the fiber. In one case it was possible to prepare and image a cross-section of the fiber, but in general the preparation of fiber cross-sections proved very difficult. In five of the 11 samples, the infrared spectra could be used to identify the overall chemical composition of the fibers, according to a published classification scheme, but the fiber components could not be spatially resolved. Difficulties that are inherent to conventional "single-point" infrared spectroscopy, such as interference fringing and sloping baselines, particularly when analyzing acrylic type fibers, were also encountered in the infrared chemical image analysis of bicomponent fibers. A number of infrared sampling techniques were investigated to overcome these problems, and recommendations for the best sampling technique are given. Chemical imaging results were compared with those obtained using conventional fiber microscopy techniques.

  17. A decision analysis framework for estimating the potential hazards for drinking water resources of chemicals used in hydraulic fracturing fluids.

    Science.gov (United States)

    Yost, Erin E; Stanek, John; Burgoon, Lyle D

    2017-01-01

    Despite growing concerns over the potential for hydraulic fracturing to impact drinking water resources, there are limited data available to identify chemicals used in hydraulic fracturing fluids that may pose public health concerns. In an effort to explore these potential hazards, a multi-criteria decision analysis (MCDA) framework was employed to analyze and rank selected subsets of these chemicals by integrating data on toxicity, frequency of use, and physicochemical properties that describe transport in water. Data used in this analysis were obtained from publicly available databases compiled by the United States Environmental Protection Agency (EPA) as part of a larger study on the potential impacts of hydraulic fracturing on drinking water. Starting with nationwide hydraulic fracturing chemical usage data from EPA's analysis of the FracFocus Chemical Disclosure Registry 1.0, MCDAs were performed on chemicals that had either noncancer toxicity values (n=37) or cancer-specific toxicity values (n=10). The noncancer MCDA was then repeated for subsets of chemicals reported in three representative states (Texas, n=31; Pennsylvania, n=18; and North Dakota, n=20). Within each MCDA, chemicals received scores based on relative toxicity, relative frequency of use, and physicochemical properties (mobility in water, volatility, persistence). Results show a relative ranking of these chemicals based on hazard potential, and provide preliminary insight into chemicals that may be more likely than others to impact drinking water resources. Comparison of nationwide versus state-specific analyses indicates regional differences in the chemicals that may be of more concern to drinking water resources, although many chemicals were commonly used and received similar overall hazard rankings. Several chemicals highlighted by these MCDAs have been reported in groundwater near areas of hydraulic fracturing activity. This approach is intended as a preliminary analysis, and represents one

  18. Near-field Optical Imagigng and Chemical Analysis

    Science.gov (United States)

    Andres, La Rosa

    1998-03-01

    Identification of molecular structures in complex mixtures represents a major challenge in chemical research today. Microfabricated devices or lab-on-a-chip that perform chemical analysis allows dynamic sampling of picoliter microenvironments and separation. The long-term goals of nanochemistry down to the femtoliter scale involve refinement of the detection limit to single-molecule. Our approach consists in designing a very sensitive near-field optical microscope (NSOM-SIAM) to explore the mesoscopic properties of organic compounds. The validity, sensitivity and unique spatial resolution of this system will be discussed for multiple analyte chemosensing.

  19. Chemical analysis of plasma-assisted antimicrobial treatment on cotton

    Science.gov (United States)

    Kan, C. W.; Lam, Y. L.; Yuen, C. W. M.; Luximon, A.; Lau, K. W.; Chen, K. S.

    2013-06-01

    This paper explores the use of plasma treatment as a pretreatment process to assist the application of antimicrobial process on cotton fabric with good functional effect. In this paper, antimicrobial finishing agent, Microfresh Liquid Formulation 9200-200 (MF), and a binder (polyurethane dispersion, Microban Liquid Formulation R10800-0, MB) will be used for treating the cotton fabric for improving the antimicrobial property and pre-treatment of cotton fabric by plasma under atmospheric pressure will be employed to improve loading of chemical agents. The chemical analysis of the treated cotton fabric will be conducted by Fourier transform Infrared Spectroscopy.

  20. An Extended Algorithm of Flexibility Analysis in Chemical Engineering Processes

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    An extended algorithm of flexibility analysis with a local adjusting method for flexibility region of chemical processes, which is based on the active constraint strategy, is proposed, which fully exploits the flexibility region of the process system operation. The hyperrectangular flexibility region determined by the extended algorithm is larger than that calculated by the previous algorithms. The limitation of the proposed algorithm due to imperfect convexity and its corresponding verification measure are also discussed. Both numerical and actual chemical process examples are presented to demonstrate the effectiveness of the new algorithm.

  1. The Impact of Flow Injection on Modern Chemical Analysis

    DEFF Research Database (Denmark)

    Hansen, Elo Harald

    There is no doubt that Flow Injection Analysis (FIA) has had a profound impact on the ways and means that modern analytical chemical procedures are performed. This is amply reflected in the voluminous scientific literature, which by the middle of 2004 passed more than 14,500 FIA-publications in i......There is no doubt that Flow Injection Analysis (FIA) has had a profound impact on the ways and means that modern analytical chemical procedures are performed. This is amply reflected in the voluminous scientific literature, which by the middle of 2004 passed more than 14,500 FIA...... and preconcentration procedures. In recent years, FIA has been supplemented by Sequential Injection Analysis (SIA) and the Lab-on-Valve (LOV) approach. Following a brief historic introduction and an account of the impact of FIA in academia, the lecture will describe these two new generations of FIA, accompanied...

  2. Mass spectrometric analysis of chemical warfare agents in support of a chemical terrorist event

    Energy Technology Data Exchange (ETDEWEB)

    Hancock, J.R.; D' Agostino, P.A.; Chenier, C.L. [Defence R and D Canada Suffield, Medicine Hat, AB (Canada)

    2003-07-01

    Chemical warfare (CW) agents are considered to be any chemicals which, through their chemical action on life processes can cause death, temporary incapacitation or permanent harm to humans or animals. In Canada, the probability of a CW terrorist attack is low despite the catastrophic consequences that would result from such an attack. The three levels of government would be responding to such an event. CW agent response training for all levels of government is offered at Defence R and D Canada-Suffield. Appropriate samples must be collected for analysis in a laboratory, as such an event would lead to a criminal investigation. Research into new methods for the identification of CW agents is being conducted by the analytical laboratory at Defence R and D Canada-Suffield. Gas chromatography and mass spectrometry (GC-MS) are being used extensively to separate and characterize CW agents in organic extracts. In the case of aqueous samples, another method might be more appropriate, since additional sample handling is required before GC-MS analysis can be performed. Minimal sample handling is required when using liquid chromatography-electrospray ionization-mass spectrometry (LC-ESI-MS) for direct analysis of CW agents. The authors demonstrated the use of LC-ESI-MS for analyzing CW agents and their hydrolysis products in aqueous samples. For the analysis of nerve agents and phosphonic acids in soil, comparable or superior results to organic extraction and GC-MS were obtained for aqueous extractions followed by LC-ESI-MS. The combination of GC-MS and LC-ESI-MS for the analysis of mustard related compounds in soil extracts from a former mustard storage area showed that the two methods are complementary in this situation. 9 refs., 3 tabs., 5 figs.

  3. Looking for chemical reaction networks exhibiting a drift along a manifold of marginally stable states.

    Science.gov (United States)

    Brogioli, Doriano

    2013-02-07

    I recently reported some examples of mass-action equations that have a continuous manifold of marginally stable stationary states [Brogioli, D., 2010. Marginally stable chemical systems as precursors of life. Phys. Rev. Lett. 105, 058102; Brogioli, D., 2011. Marginal stability in chemical systems and its relevance in the origin of life. Phys. Rev. E 84, 031931]. The corresponding chemical reaction networks show nonclassical effects, i.e. a violation of the mass-action equations, under the effect of the concentration fluctuations: the chemical system drifts along the marginally stable states. I proposed that this effect is potentially involved in abiogenesis. In the present paper, I analyze the mathematical properties of mass-action equations of marginally stable chemical reaction networks. The marginal stability implies that the mass-action equations obey some conservation law; I show that the mathematical properties of the conserved quantity characterize the motion along the marginally stable stationary state manifold, i.e. they allow to predict if the fluctuations give rise to a random walk or a drift under the effect of concentration fluctuations. Moreover, I show that the presence of the drift along the manifold of marginally stable stationary-states is a critical property, i.e. at least one of the reaction constants must be fine tuned in order to obtain the drift.

  4. Transition state trajectory stability determines barrier crossing rates in chemical reactions induced by time-dependent oscillating fields

    CERN Document Server

    Craven, Galen T; Hernandez, Rigoberto

    2015-01-01

    When a chemical reaction is driven by an external field, the transition state that the system must pass through as it changes from reactant to product -for example, an energy barrier- becomes time-dependent. We show that for periodic forcing the rate of barrier crossing can be determined through stability analysis of the non-autonomous transition state. Specifically, strong agreement is observed between the difference in the Floquet exponents describing stability of the transition state trajectory, which defines a recrossing-free dividing surface [G. T. Craven, T. Bartsch, and R. Hernandez, Phys. Rev. E 89, 040801(R) (2014)], and the rates calculated by simulation of ensembles of trajectories. This result opens the possibility to extract rates directly from the intrinsic stability of the transition state, even when it is time-dependent, without requiring a numerically-expensive simulation of the long-time dynamics of a large ensemble of trajectories.

  5. Chemical-state imaging of Li using scanning Auger electron microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Ishida, Nobuyuki, E-mail: ISHIDA.Nobuyuki@nims.go.jp [Global Research Center for Environment and Energy based on Nanomaterials Science (GREEN), National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047 (Japan); Fujita, Daisuke [Global Research Center for Environment and Energy based on Nanomaterials Science (GREEN), National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047 (Japan); Advanced Nanocharacterization Unit, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047 (Japan)

    2013-02-15

    Highlights: •Scanning Auger electron microscopy is used to image chemical states of Li. •The combined use of AES and EELS signals for the elemental mapping is powerful. •Distribution corresponding to metallic and oxidized states of Li can be imaged. -- Abstract: The demand for measurement tools to detect Li with high spatial resolution and precise chemical sensitivity is increasing with the spread of lithium-ion batteries (LIBs) for use in a wide range of applications. In this work, scanning Auger electron microscopy (SAM) is used to image chemical states of a partially oxidized Li surface on the basis of the Auger electron spectroscopy (AES) and electron energy loss spectroscopy (EELS) data obtained during an oxidation process of a metal Li. We show that distribution of metallic and oxidized states of Li is clearly imaged by mapping the intensity of the corresponding AES and EELS peaks. Furthermore, a tiny difference in the extent of oxidation can be distinguished by comparing the elemental map of an AES peak with that of an EELS peak owing to the different behaviors of those signals to the chemical states of Li.

  6. A Numerical Analysis of the Transient Response of an Ablation System Including Effects of Thermal Nonequilibrium, Mass Transfer and Chemical Kinetics. Ph.D Thesis - Virginia Polytechnic Inst. and State Univ.

    Science.gov (United States)

    Clark, R. K.

    1972-01-01

    The differential equations governing the transient response of a one-dimensional ablative thermal protection system undergoing stagnation ablation are derived. These equations are for thermal nonequilibrium effects between the pyrolysis gases and the char layer and kinetically controlled chemical reactions and mass transfer between the pyrolysis gases and the char layer. The boundary conditions are written for the particular case of stagnation heating with surface removal by oxidation or sublimation and pyrolysis of the uncharred layer occurring in a plane. The governing equations and boundary conditions are solved numerically using the modified implicit method (Crank-Nicolson method). Numerical results are compared with exact solutions for a number of simplified cases. The comparison is favorable in each instance.

  7. Chemical Fingerprint Analysis and Quantitative Analysis of Rosa rugosa by UPLC-DAD

    Directory of Open Access Journals (Sweden)

    Sanawar Mansur

    2016-12-01

    Full Text Available A method based on ultra performance liquid chromatography with a diode array detector (UPLC-DAD was developed for quantitative analysis of five active compounds and chemical fingerprint analysis of Rosa rugosa. Ten batches of R. rugosa collected from different plantations in the Xinjiang region of China were used to establish the fingerprint. The feasibility and advantages of the used UPLC fingerprint were verified for its similarity evaluation by systematically comparing chromatograms with professional analytical software recommended by State Food and Drug Administration (SFDA of China. In quantitative analysis, the five compounds showed good regression (R2 = 0.9995 within the test ranges, and the recovery of the method was in the range of 94.2%–103.8%. The similarities of liquid chromatography fingerprints of 10 batches of R. rugosa were more than 0.981. The developed UPLC fingerprint method is simple, reliable, and validated for the quality control and identification of R. rugosa. Additionally, simultaneous quantification of five major bioactive ingredients in the R. rugosa samples was conducted to interpret the consistency of the quality test. The results indicated that the UPLC fingerprint, as a characteristic distinguishing method combining similarity evaluation and quantification analysis, can be successfully used to assess the quality and to identify the authenticity of R. rugosa.

  8. Chemical Fingerprint Analysis and Quantitative Analysis of Rosa rugosa by UPLC-DAD.

    Science.gov (United States)

    Mansur, Sanawar; Abdulla, Rahima; Ayupbec, Amatjan; Aisa, Haji Akbar

    2016-12-21

    A method based on ultra performance liquid chromatography with a diode array detector (UPLC-DAD) was developed for quantitative analysis of five active compounds and chemical fingerprint analysis of Rosa rugosa. Ten batches of R. rugosa collected from different plantations in the Xinjiang region of China were used to establish the fingerprint. The feasibility and advantages of the used UPLC fingerprint were verified for its similarity evaluation by systematically comparing chromatograms with professional analytical software recommended by State Food and Drug Administration (SFDA) of China. In quantitative analysis, the five compounds showed good regression (R² = 0.9995) within the test ranges, and the recovery of the method was in the range of 94.2%-103.8%. The similarities of liquid chromatography fingerprints of 10 batches of R. rugosa were more than 0.981. The developed UPLC fingerprint method is simple, reliable, and validated for the quality control and identification of R. rugosa. Additionally, simultaneous quantification of five major bioactive ingredients in the R. rugosa samples was conducted to interpret the consistency of the quality test. The results indicated that the UPLC fingerprint, as a characteristic distinguishing method combining similarity evaluation and quantification analysis, can be successfully used to assess the quality and to identify the authenticity of R. rugosa.

  9. Development of microfluidic devices for chemical analysis and fluid handling

    OpenAIRE

    Egidi, Giovanni; de Rooij, Nicolas F

    2004-01-01

    Miniaturization of chemical analysis and synthesis systems improve throughput, performance and accessibility, and lead to significantly reduced costs. In this work are described several components that find place in the process of miniaturization. This work is developed in the frame of the project CREAM (Cartridges with molecularly imprinted Recognition Elements for Antibiotic residues Monitoring in Milk). Antibiotics are widely used to treat cows' diseases, and traces can be found in milk so...

  10. Electrochemical approaches for chemical and biological analysis on Mars

    Science.gov (United States)

    Kounaves, Samuel P.

    2003-01-01

    Obtaining in situ chemical data from planetary bodies such as Mars or Europa can present significant challenges. The one analytical technique that has many of the requisite characteristics to meet such a challenge is electroanalysis. Described here are three electroanalytical devices designed for in situ geochemical and biological analysis on Mars. The Mars Environmental Compatibility Assessment (MECA) was built and flight qualified for the now cancelled NASA Mars 2001 Lander. Part of MECA consisted of four "cells" containing arrays of electrochemical based sensors for measuring the ionic species in soil samples. A next-generation MECA, the Robotic Chemical Analysis Laboratory (RCAL), uses a carousel-type system to allow for greater customization of analytical procedures. A second instrument, proposed as part of the 2007 CryoScout mission, consists of a flow-through inorganic chemical analyzer (MICA). CryoScout is a torpedo-like device designed for subsurface investigation of the stratigraphic climate record embedded in Mars' north polar cap. As the CryoScout melts its way through the ice cap, MICA will collect and analyze the meltwater for a variety of inorganics and chemical parameters. By analyzing the chemistry locked in the layers of dust, salt, and ice, geologists will be able to determine the recent history of climate, water, and atmosphere on Mars and link it to the past. Finally, electroanalysis shows its abilities in the detection of possible microorganism on Mars or elsewhere in the solar system. To identify an unknown microorganism, one that may not even use Earth-type biochemistry, requires a detection scheme which makes minimal assumptions and looks for the most general features. Recent work has demonstrated that the use of an array of electrochemical sensors which monitors the changes in a solution via electrical conductivity, pH, and ion selective electrodes, can be used to detect minute chemical perturbations caused by the growth of bacteria and

  11. Handling the influence of chemical shift in amplitude-modulated heteronuclear dipolar recoupling solid-state NMR

    Science.gov (United States)

    Basse, Kristoffer; Shankar, Ravi; Bjerring, Morten; Vosegaard, Thomas; Nielsen, Niels Chr.; Nielsen, Anders B.

    2016-09-01

    We present a theoretical analysis of the influence of chemical shifts on amplitude-modulated heteronuclear dipolar recoupling experiments in solid-state NMR spectroscopy. The method is demonstrated using the Rotor Echo Short Pulse IRrAdiaTION mediated Cross-Polarization (RESPIRATIONCP) experiment as an example. By going into the pulse sequence rf interaction frame and employing a quintuple-mode operator-based Floquet approach, we describe how chemical shift offset and anisotropic chemical shift affect the efficiency of heteronuclear polarization transfer. In this description, it becomes transparent that the main attribute leading to non-ideal performance is a fictitious field along the rf field axis, which is generated from second-order cross terms arising mainly between chemical shift tensors and themselves. This insight is useful for the development of improved recoupling experiments. We discuss the validity of this approach and present quaternion calculations to determine the effective resonance conditions in a combined rf field and chemical shift offset interaction frame transformation. Based on this, we derive a broad-banded version of the RESPIRATIONCP experiment. The new sequence is experimentally verified using SNNFGAILSS amyloid fibrils where simultaneous 15N → 13CO and 15N → 13Cα coherence transfer is demonstrated on high-field NMR instrumentation, requiring great offset stability.

  12. SURFACE AND LIGHTNING SOURCES OF NITROGEN OXIDES OVER THE UNITED STATES: MAGNITUDES, CHEMICAL EVOLUTION, AND OUTFLOW

    Science.gov (United States)

    We use observations from two aircraft during the ICARTT campaign over the eastern United States and North Atlantic during summer 2004, interpreted with a global 3-D model of tropospheric chemistry (GEOS-Chem) to test current understanding of regional sources, chemical evolution...

  13. Chemical Engineering Education in Japan and the United States: A Perspective (Part 2).

    Science.gov (United States)

    Floyd, Sigmund

    1988-01-01

    Compares graduate chemical engineering education practices of the U.S. and Japan. States that Japanese universities have set time limits on degrees due to industrial hiring practices. Concludes that Japanese graduates are highly trained and uniform. They tend to stay in the same job throughout their career. (MVL)

  14. The chemical state of arsenic in minerals of environmental interest--an XPS and an XAES study.

    Science.gov (United States)

    Atzei, Davide; Da Pelo, Stefania; Elsener, Bernhard; Fantauzzi, Marzia; Frau, Franco; Pierfranco, Lattanzi; Rossi, Antonella

    2003-01-01

    A systematic analytical study using X-ray photoelectron spectroscopy (XPS) and X-ray induced Auger electron spectroscopy (XAES) has been carried out to characterize the chemical state of arsenic in complex environmental samples. The conventional approach, which relies on the chemical shift of the core levels As3d, provides ambiguous results in determining the chemical environment of arsenic. A more accurate approach, based on the Auger parameter and on the Wagner (Chemical State) plot, which combines AsLMM kinetic energy and As3d binding energy, was adopted. This novel method for determining the chemical state of arsenic was employed to completely characterize arsenic in complex environmental samples.

  15. Inferring the unobserved chemical state of the atmosphere: idealized data assimilation experiments

    Science.gov (United States)

    Knote, C. J.; Barré, J.; Eckl, M.; Hornbrook, R. S.; Wiedinmyer, C.; Emmons, L. K.; Orlando, J. J.; Tyndall, G. S.; Arellano, A. F.

    2015-12-01

    Chemical data assimilation in numerical models of the atmosphere is a venture into uncharted territory, into a world populated by a vast zoo of chemical compounds with strongly non-linear interactions. Commonly assimilated observations exist for only a selected few of those key gas phase compounds (CO, O3, NO2), and assimilating those in models assuming linearity begs the question of: To what extent we can infer the remainder to create a new state of the atmosphere that is chemically sound and optimal? In our work we present the first systematic investigation of sensitivities that exist between chemical compounds under varying ambient conditions in order to inform scientists on the potential pitfalls when assimilating single/few chemical compounds into complex 3D chemistry transport models. In order to do this, we developed a box-modeling tool (BOXMOX) based on the Kinetic PreProcessor (KPP, http://people.cs.vt.edu/~asandu/Software/Kpp/) in which we can conduct simulations with a suite of 'mechanisms', sets of differential equations describing atmospheric photochemistry. The box modeling approach allows us to sample a large variety of atmospheric conditions (urban, rural, biogenically dominated, biomass burning plumes) to capture the range of chemical conditions that typically exist in the atmosphere. Included in our suite are 'lumped' mechanisms typically used in regional and global chemistry transport models (MOZART, RACM, RADM2, SAPRC99, CB05, CBMZ) as well as the Master Chemical Mechanism (MCM, U. Leeds). We will use an Observing System Simulation Experiment approach with the MCM prediction as 'nature' or 'true' state, assimilating idealized synthetic observations (from MCM) into the different ‚lumped' mechanisms under various environments. Two approaches to estimate the sensitivity of the chemical system will be compared: 1) adjoint: using Jacobians computed by KPP and 2) ensemble: by perturbing emissions, temperature, photolysis rates, entrainment, etc., in

  16. Chemical Composition and Disruption of Quorum Sensing Signaling in Geographically Diverse United States Propolis

    Science.gov (United States)

    Savka, Michael A.; Dailey, Lucas; Popova, Milena; Mihaylova, Ralitsa; Merritt, Benjamin; Masek, Marissa; Le, Phuong; Nor, Sharifah Radziah Mat; Ahmad, Muhammad; Hudson, André O.; Bankova, Vassya

    2015-01-01

    Propolis or bee glue has been used for centuries for various purposes and is especially important in human health due to many of its biological and pharmacological properties. In this work we showed quorum sensing inhibitory (QSI) activity of ten geographically distinct propolis samples from the United States using the acyl-homoserine lactone- (AHL-) dependent Chromobacterium violaceum strain CV026. Based on GC-MS chemical profiling the propolis samples can be classified into several groups that are as follows: (1) rich in cinnamic acid derivatives, (2) rich in flavonoids, and (3) rich in triterpenes. An in-depth analysis of the propolis from North Carolina led to the isolation and identification of a triterpenic acid that was recently isolated from Hondurian propolis (Central America) and ethyl ether of p-coumaric alcohol not previously identified in bee propolis. QSI activity was also observed in the second group US propolis samples which contained the flavonoid pinocembrin in addition to other flavonoid compounds. The discovery of compounds that are involved in QSI activity has the potential to facilitate studies that may lead to the development of antivirulence therapies that can be complementary and/or alternative treatments against antibiotic resistant bacterial pathogens and/or emerging pathogens that have yet to be identified. PMID:25960752

  17. Octafluorodirhenate(III) Revisited: Solid-State Preparation, Characterization, and Multiconfigurational Quantum Chemical Calculations.

    Science.gov (United States)

    Mariappan Balasekaran, Samundeeswari; Todorova, Tanya K; Pham, Chien Thang; Hartmann, Thomas; Abram, Ulrich; Sattelberger, Alfred P; Poineau, Frederic

    2016-06-01

    A simple method for the high-yield preparation of (NH4)2[Re2F8]·2H2O has been developed that involves the reaction of (n-Bu4N)2[Re2Cl8] with molten ammonium bifluoride (NH4HF2). Using this method, the new salt [NH4]2[Re2F8]·2H2O was prepared in ∼90% yield. The product was characterized in solution by ultraviolet-visible light (UV-vis) and (19)F nuclear magnetic resonance ((19)F NMR) spectroscopies and in the solid-state by elemental analysis, powder X-ray diffraction (XRD), and infrared (IR) spectroscopy. Multiconfigurational CASSCF/CASPT2 quantum chemical calculations were performed to investigate the molecular and electronic structure, as well as the electronic absorption spectrum of the [Re2F8](2-) anion. The metal-metal bonding in the Re2(6+) unit was quantified in terms of effective bond order (EBO) and compared to that of its [Re2Cl8](2-) and [Re2Br8](2-) analogues.

  18. Chemical Composition and Disruption of Quorum Sensing Signaling in Geographically Diverse United States Propolis

    Directory of Open Access Journals (Sweden)

    Michael A. Savka

    2015-01-01

    Full Text Available Propolis or bee glue has been used for centuries for various purposes and is especially important in human health due to many of its biological and pharmacological properties. In this work we showed quorum sensing inhibitory (QSI activity of ten geographically distinct propolis samples from the United States using the acyl-homoserine lactone- (AHL- dependent Chromobacterium violaceum strain CV026. Based on GC-MS chemical profiling the propolis samples can be classified into several groups that are as follows: (1 rich in cinnamic acid derivatives, (2 rich in flavonoids, and (3 rich in triterpenes. An in-depth analysis of the propolis from North Carolina led to the isolation and identification of a triterpenic acid that was recently isolated from Hondurian propolis (Central America and ethyl ether of p-coumaric alcohol not previously identified in bee propolis. QSI activity was also observed in the second group US propolis samples which contained the flavonoid pinocembrin in addition to other flavonoid compounds. The discovery of compounds that are involved in QSI activity has the potential to facilitate studies that may lead to the development of antivirulence therapies that can be complementary and/or alternative treatments against antibiotic resistant bacterial pathogens and/or emerging pathogens that have yet to be identified.

  19. Chemical Abundance Analysis of Moving Group W11450 (Latham 1)

    CERN Document Server

    O'Connell, Julia E; Frinchaboy, Peter M

    2016-01-01

    We present elemental abundances for all seven stars in Moving Group W11450 (Latham 1) to determine if they may be chemically related. These stars appear to be both spatially and kinematically related, but no spectroscopic abundance analysis exists in literature. Abundances for eight elements were derived via equivalent width analyses of high resolution (R $\\sim$60,000), high signal-to-noise ratio ($\\langle$SNR$\\rangle\\sim$100) spectra obtained with the Otto Struve 2.1m telescope and Sandiford Echelle Spectrograph at McDonald Observatory. The large star-to-star scatter in metallicity, -0.55 $\\leq$ [Fe/H] $\\leq$ 0.06 dex ($\\sigma$= 0.25), implies these stars were not produced from the same chemically homogeneous molecular cloud, and are therefore not part of a remnant or open cluster as previously proposed. Prior to this analysis, it was suggested that two stars in the group, W11449 & W11450, are possible wide binaries. The candidate wide binary pair show similar chemical abundance patterns with not only ir...

  20. Application and state of development for remote chemical sensors in environmental monitoring: A literature review

    Energy Technology Data Exchange (ETDEWEB)

    Schabron, J.F.; Niss, N.D.; Hart, B.K.

    1991-09-01

    A study was performed on chemical sensor technology currently available and under development. The information was compiled into a format wherein information on the sensors is listed in a comparable manner. An introductory section is provided to illustrate the regulatory environment in which such sensor technology will be used. This information should allow corporations or federal agencies ready access to useful information for the potential licensing of sensor technology for commercial development or specific environmental monitoring operations. Although every attempt was made to identify as many chemical sensors as possible, we recognize that some may be missed inadvertently. The accuracy of the information provided by the various sources regarding the state of development for the various sensors was not verified. Judgments or opinions regarding the actual state of development or utility of these devices are not included in this report. However, we feel that this report accurately reflects the state of the art at the present time.

  1. Application and state of development for remote chemical sensors in environmental monitoring: A literature review

    Energy Technology Data Exchange (ETDEWEB)

    Schabron, J.F.; Niss, N.D.; Hart, B.K.

    1991-09-01

    A study was performed on chemical sensor technology currently available and under development. The information was compiled into a format wherein information on the sensors is listed in a comparable manner. As introductory section is provided to illustrate the regulatory environment in which such sensor technology will be used. This information should allow corporations or federal agencies ready access to useful information for the potential licensing of sensor technology for commercial development or specific environmental monitoring operations. Although every attempt was made to identify as many chemical sensors as possible, we recognize that some may be missed inadvertently. The accuracy of the information provided by the various sources regarding the state of development for the various sensors was not verified. Judgments or opinions regarding the actual state of development or utility of these devices are not included in this report. However, we feel that this report accurately reflects the state of the art at the present time.

  2. Proximate analysis, backwards stepwise regression between gross calorific value, ultimate and chemical analysis of wood.

    Science.gov (United States)

    Telmo, C; Lousada, J; Moreira, N

    2010-06-01

    The gross calorific value (GCV), proximate, ultimate and chemical analysis of debark wood in Portugal were studied, for future utilization in wood pellets industry and the results compared with CEN/TS 14961. The relationship between GCV, ultimate and chemical analysis were determined by multiple regression stepwise backward. The treatment between hardwoods-softwoods did not result in significant statistical differences for proximate, ultimate and chemical analysis. Significant statistical differences were found in carbon for National (hardwoods-softwoods) and (National-tropical) hardwoods in volatile matter, fixed carbon, carbon and oxygen and also for chemical analysis in National (hardwoods-softwoods) for F and (National-tropical) hardwoods for Br. GCV was highly positively related to C (0.79 * * *) and negatively to O (-0.71 * * *). The final independent variables of the model were (C, O, S, Zn, Ni, Br) with R(2)=0.86; F=27.68 * * *. The hydrogen did not contribute statistically to the energy content.

  3. In Situ Solid-State Reactions Monitored by X-ray Absorption Spectroscopy: Temperature-Induced Proton Transfer Leads to Chemical Shifts.

    Science.gov (United States)

    Stevens, Joanna S; Walczak, Monika; Jaye, Cherno; Fischer, Daniel A

    2016-10-24

    The dramatic colour and phase alteration with the solid-state, temperature-dependent reaction between squaric acid and 4,4'-bipyridine has been probed in situ with X-ray absorption spectroscopy. The electronic and chemical sensitivity to the local atomic environment through chemical shifts in the near-edge X-ray absorption fine structure (NEXAFS) revealed proton transfer from the acid to the bipyridine base through the change in nitrogen protonation state in the high-temperature form. Direct detection of proton transfer coupled with structural analysis elucidates the nature of the solid-state process, with intermolecular proton transfer occurring along an acid-base chain followed by a domino effect to the subsequent acid-base chains, leading to the rapid migration along the length of the crystal. NEXAFS thereby conveys the ability to monitor the nature of solid-state chemical reactions in situ, without the need for a priori information or long-range order.

  4. Analysis of chemical composition of high viscous oils

    Directory of Open Access Journals (Sweden)

    Irina Germanovna Yashchenko

    2014-07-01

    Full Text Available The spatial distribution of viscous oils which are considered as an important reserve for oil-production in future were studied on base of information from global database on oil physical and chemical properties. Changes in chemical composition of viscous oils in different basins and continents were analyzed as well. It is shown, on average, viscous oils are sulfur-bearing, low paraffin, highly resinous oils with an average content of asphaltenes and low content of the fraction boiling at 200 C. Study results of viscous oils peculiarities of Canada, Russia and Venezuela are given. The analysis results can be used to determine the optimal layouts and conditions of oil transportation, to improve the search methods of geochemical exploration, and to solve other problems in the oil chemistry.

  5. Chemical Bond Analysis of Single Crystal Growth of Magnesium Oxide

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Starting from the crystallographic structure of magnesium oxide (MgO), both the chemical bond model of solids and Pauling's third rule (polyhedral sharing rule) were employed to quantitatively analyze the chemical bonding structure of constituent atoms and single crystal growth. Our analytical results show that MgO single crystals prefer to grow along the direction and the growth rate of the {100} plane is the slowest one. Therefore, the results show that the {100} plane of MgO crystals can be the ultimate morphology face, which is in a good agreement with our previous experimental results. The study indicate that the structure analysis is an effective tool to control the single-crystal growth.

  6. Fault Diagnosis in Chemical Process Based on Self-organizing Map Integrated with Fisher Discriminant Analysis

    Institute of Scientific and Technical Information of China (English)

    CHEN Xinyi; YAN Xuefeng

    2013-01-01

    Fault diagnosis and monitoring are very important for complex chemical process.There are numerous methods that have been studied in this field,in which the effective visualization method is still challenging.In order to get a better visualization effect,a novel fault diagnosis method which combines self-organizing map (SOM) with Fisher discriminant analysis (FDA) is proposed.FDA can reduce the dimension of the data in terms of maximizing the separability of the classes.After feature extraction by FDA,SOM can distinguish the different states on the output map clearly and it can also be employed to monitor abnormal states.Tennessee Eastman (TE) process is employed to illustrate the fault diagnosis and monitoring performance of the proposed method.The result shows that the SOM integrated with FDA method is efficient and capable for real-time monitoring and fault diagnosis in complex chemical process.

  7. Hot QCD equation of state and quark-gluon plasma-- finite quark chemical potential

    CERN Document Server

    Chandra, Vinod

    2008-01-01

    We explore the relevance of a hot QCD equation of state of $O[g^6\\ln(1/g)]$, which has been obtained\\cite{avrn} for non-vanishing quark-chemical potentials to heavy ion collisions. Employing a method proposed in a recent paper \\cite{chandra1}, we use the EOS to determine a host of thermodynamic quantities, the energy density, specific heat, entropy dnesity, and the temperature dependence of screening lengths, with the behaviour of QGP at RHIC and LHC in mind. We also investigate the sensitivity of these observables to the quark chemical potential.

  8. Multi-GPU unsteady 2D flow simulation coupled with a state-to-state chemical kinetics

    Science.gov (United States)

    Tuttafesta, Michele; Pascazio, Giuseppe; Colonna, Gianpiero

    2016-10-01

    In this work we are presenting a GPU version of a CFD code for high enthalpy reacting flow, using the state-to-state approach. In supersonic and hypersonic flows, thermal and chemical non-equilibrium is one of the fundamental aspects that must be taken into account for the accurate characterization of the plasma and state-to-state kinetics is the most accurate approach used for this kind of problems. This model consists in writing a continuity equation for the population of each vibrational level of the molecules in the mixture, determining at the same time the species densities and the distribution of the population in internal levels. An explicit scheme is employed here to integrate the governing equations, so as to exploit the GPU structure and obtain an efficient algorithm. The best performances are obtained for reacting flows in state-to-state approach, reaching speedups of the order of 100, thanks to the use of an operator splitting scheme for the kinetics equations.

  9. QUALITY ASSURANCE GUIDELINES FOR LABORATORIES PERFORMING FORENSIC ANALYSIS OF CHEMICAL TERRORISM

    Science.gov (United States)

    The Scientific Working Group on Forensic Analysis of Chemical Terrorism (SWGFACT) has developed the following quality assurance guidelines to provide laboratories engaged in forensic analysis of chemical evidence associated with terrorism a framework to implement a quality assura...

  10. Moisture-induced solid state instabilities in α-chymotrypsin and their reduction through chemical glycosylation

    Directory of Open Access Journals (Sweden)

    Solá Ricardo J

    2010-08-01

    Full Text Available Abstract Background Protein instability remains the main factor limiting the development of protein therapeutics. The fragile nature (structurally and chemically of proteins makes them susceptible to detrimental events during processing, storage, and delivery. To overcome this, proteins are often formulated in the solid-state which combines superior stability properties with reduced operational costs. Nevertheless, solid protein pharmaceuticals can also suffer from instability problems due to moisture sorption. Chemical protein glycosylation has evolved into an important tool to overcome several instability issues associated with proteins. Herein, we employed chemical glycosylation to stabilize a solid-state protein formulation against moisture-induced deterioration in the lyophilized state. Results First, we investigated the consequences of moisture sorption on the stability and structural conformation of the model enzyme α-chymotrypsin (α-CT under controlled humidity conditions. Results showed that α-CT aggregates and inactivates as a function of increased relative humidity (RH. Furthermore, α-CT loses its native secondary and tertiary structure rapidly at increasing RH. In addition, H/D exchange studies revealed that α-CT structural dynamics increased at increasing RH. The magnitude of the structural changes in tendency parallels the solid-state instability data (i.e., formation of buffer-insoluble aggregates, inactivation, and loss of native conformation upon reconstitution. To determine if these moisture-induced instability issues could be ameliorated by chemical glycosylation we proceeded to modify our model protein with chemically activated glycans of differing lengths (lactose and dextran (10 kDa. The various glycoconjugates showed a marked decrease in aggregation and an increase in residual activity after incubation. These stabilization effects were found to be independent of the glycan size. Conclusion Water sorption leads to

  11. Thermodynamic and chemical kinetic analysis of a 5 kw, compact steam reformer - PEMFC system

    Energy Technology Data Exchange (ETDEWEB)

    Acevedo, Luis Evelio Garcia; Oliveira, Amir Antonio Martins [Universidade Federal de Santa Catarina (UFSC), Florianopolis, SC (Brazil). Dept. de Engenharia Mecanica], e-mail: evelio@labcet.ufsc.br, e-mail: amirol@emc.ufsc.br

    2006-07-01

    Here we present a thermodynamic and chemical kinetic analysis of the methane steam reforming for production of 5 kw of electrical power in a PEM fuel cell. The equilibrium analysis is based on the method of element potentials to find the state of minimum Gibbs free energy for the system and provides the equilibrium concentration of the reforming products. The objective of this analysis is to obtain the range of reforming temperature, pressure and steam-methane molar ratio that results in maximum hydrogen production subjected to low carbon monoxide production and negligible coke formation. The thermal analysis provides the heat transfer rates associated with the individual processes of steam production, gas-phase superheating and reforming necessary to produce 5 kw of electrical power in a PEM fuel cell and allows for the calculation of thermal efficiencies. Then, the chemical reaction pathways for hydrogen production in steam reforming are discussed and the available chemical, adsorption and equilibrium constants are analyzed in terms of thermodynamic consistency. This analysis provides the framework for the reactor sizing and for establishing the adequate operation conditions. (author)

  12. Charge-displacement analysis for excited states

    Energy Technology Data Exchange (ETDEWEB)

    Ronca, Enrico, E-mail: enrico@thch.unipg.it; Tarantelli, Francesco, E-mail: francesco.tarantelli@unipg.it [Istituto CNR di Scienze e Tecnologie Molecolari, via Elce di Sotto 8, I-06123 Perugia (Italy); Dipartimento di Chimica, Biologia e Biotecnologie, Università degli Studi di Perugia, via Elce di Sotto 8, I-06123 Perugia (Italy); Pastore, Mariachiara, E-mail: chiara@thch.unipg.it; Belpassi, Leonardo; De Angelis, Filippo [Istituto CNR di Scienze e Tecnologie Molecolari, via Elce di Sotto 8, I-06123 Perugia (Italy); Angeli, Celestino; Cimiraglia, Renzo [Dipartimento di Scienze Chimiche e Farmaceutiche, Università degli Studi di Ferrara, via Borsari 46, I-44100 Ferrara (Italy)

    2014-02-07

    We extend the Charge-Displacement (CD) analysis, already successfully employed to describe the nature of intermolecular interactions [L. Belpassi et al., J. Am. Chem. Soc. 132, 13046 (2010)] and various types of controversial chemical bonds [L. Belpassi et al., J. Am. Chem. Soc. 130, 1048 (2008); N. Salvi et al., Chem. Eur. J. 16, 7231 (2010)], to study the charge fluxes accompanying electron excitations, and in particular the all-important charge-transfer (CT) phenomena. We demonstrate the usefulness of the new approach through applications to exemplary excitations in a series of molecules, encompassing various typical situations from valence, to Rydberg, to CT excitations. The CD functions defined along various spatial directions provide a detailed and insightful quantitative picture of the electron displacements taking place.

  13. Integrated polymer waveguides for absorbance detection in chemical analysis systems

    DEFF Research Database (Denmark)

    Mogensen, Klaus Bo; El-Ali, Jamil; Wolff, Anders

    2003-01-01

    . The emphasis of this paper is on the signal-to-noise ratio of the detection and its relation to the sensitivity. Two absorbance cells with an optical path length of 100 μm and 1000 μm were characterized and compared in terms of sensitivity, limit of detection and effective path length for measurements......A chemical analysis system for absorbance detection with integrated polymer waveguides is reported for the first time. The fabrication procedure relies on structuring of a single layer of the photoresist SU-8, so both the microfluidic channel network and the optical components, which include planar...

  14. Probabilistic Approach to Risk Analysis of Chemical Spills at Sea

    Institute of Scientific and Technical Information of China (English)

    Magda Bogalecka; Krzysztof Kolowrocki

    2006-01-01

    Risk analysis of chemical spills at sea and their consequences for sea environment are discussed. Mutual interactions between the process of the sea accident initiating events, the process of the sea environment threats, and the process of the sea environment degradation are investigated. To describe these three particular processes, the separate semi-Markov models are built. Furthermore, these models are jointed into one general model of these processes interactions.Moreover, some comments on the method for statistical identification of the considered models are proposed.

  15. Comparison of descriptive sensory analysis and chemical analysis for oxidative changes in milk

    DEFF Research Database (Denmark)

    Hedegaard, R V; Kristensen, D; Nielsen, Jacob Holm;

    2006-01-01

    products. The milk samples were evaluated in parallel by descriptive sensory analysis by a trained panel, and the correlation between the chemical analysis and the descriptive sensory analysis was evaluated. The fatty acid composition of the 3 types of milk was found to influence the oxidative...... and lipolytic changes occurring in the milk during chill storage for 4 d. Sensory analysis and chemical analysis showed high correlation between the typical descriptors for oxidation such as cardboard, metallic taste, and boiled milk and specific chemical markers for oxidation such as hexanal. Notably, primary...... oxidation products (i.e., lipid hydroperoxides) and even the tendency of formation of radicals as measured by electron spin resonance spectroscopy were also highly correlated to the sensory descriptors for oxidation. Electron spin resonance spectroscopy should accordingly be further explored as a routine...

  16. Chemical structure analysis of starch and cellulose derivatives.

    Science.gov (United States)

    Mischnick, Petra; Momcilovic, Dane

    2010-01-01

    Starch and cellulose are the most abundant and important representatives of renewable biomass. Since the mid-19th century their properties have been changed by chemical modification for commercial and scientific purposes, and there substituted polymers have found a wide range of applications. However, the inherent polydispersity and supramolecular organization of starch and cellulose cause the products resulting from their modification to display high complexity. Chemical composition analysis of these mixtures is therefore a challenging task. Detailed knowledge on substitution patterns is fundamental for understanding structure-property relationships in modified cellulose and starch, and thus also for the improvement of reproducibility and rational design of properties. Substitution patterns resulting from kinetically or thermodynamically controlled reactions show certain preferences for the three available hydroxyl functions in (1→4)-linked glucans. Spurlin, seventy years ago, was the first to describe this in an idealized model, and nowadays this model has been extended and related to the next hierarchical levels, namely, the substituent distribution in and over the polymer chains. This structural complexity, with its implications for data interpretation, and the analytical approaches developed for its investigation are outlined in this article. Strategies and methods for the determination of the average degree of substitution (DS), monomer composition, and substitution patterns at the polymer level are presented and discussed with respect to their limitations and interpretability. Nuclear magnetic resonance spectroscopy, chromatography, capillary electrophoresis, and modern mass spectrometry (MS), including tandem MS, are the main instrumental techniques employed, in combination with appropriate sample preparation by chemical and enzymatic methods.

  17. Chemical Analysis of NOx Removal Under Different Reduced Electric Fields

    Science.gov (United States)

    Haddouche, A.; Lemerini, M.

    2015-07-01

    This work presents a chemical kinetic analysis of different species involved in nitrogen-oxygen mixed gas induced by stationary corona discharge at room temperature and atmospheric pressure. This study takes into account twenty different chemical species participating in one hundred and seventy selected chemical reactions. The reaction rate coefficients are taken from the literature, and the density is analyzed by the continuity equation without the diffusion term. A large number of investigations considered the removal of NOx showing the effects of N, O and O3 radicals. The aim of the present simulation is to complete these studies by analysing various plasma species under different reduced electric fields in the range of 100-200 Td (1 Td=10-21 V·m2). In particular, we analyze the time evolution of depopulation (10-9-10-3 s) of NOx. We have found that the depopulation rate of NO and NO2 is substantially affected by the rise of reduced electric field as it grows from 100 Td to 200 Td. This allows us to ascertain the important role played by the reduced electric field.

  18. Coupling passive sampling with in vitro bioassays and chemical analysis to understand combined effects of bioaccumulative chemicals in blood of marine turtles.

    Science.gov (United States)

    Jin, Ling; Escher, Beate I; Limpus, Colin J; Gaus, Caroline

    2015-11-01

    Conventional target analysis of biological samples such as blood limits our ability to understand mixture effects of chemicals. This study aimed to establish a rapid passive sampling technique using the polymer polydimethylsiloxane (PDMS) for exhaustive extraction of mixtures of neutral organic chemicals accumulated in blood of green turtles, in preparation for screening in in vitro bioassays. We designed a PDMS-blood partitioning system based on the partition coefficients of chemicals between PDMS and major blood components. The sampling kinetics of hydrophobic test chemicals (polychlorinated dibenzo-p-dioxins; PCDDs) from blood into PDMS were reasonably fast reaching steady state in turtles with known concentrations of PCDD/Fs, dioxin-like PCBs, PBDEs and organochlorine pesticides. The quantified chemicals explained most of the dioxin-like activity (69-98%), but less than 0.4% of the oxidative stress response. The results demonstrate the applicability of PDMS-based passive sampling to extract bioaccumulative chemicals from blood as well as the value of in vitro bioassays for capturing the combined effects of unknown and known chemicals.

  19. TOF-SIMS analysis of polystyrene/polybutadiene blend using chemical derivatization and multivariate analysis

    Science.gov (United States)

    Kono, Teiichiro; Iwase, Eijiro; Kanamori, Yukiko

    2008-12-01

    Chemical imaging with high spatial resolution is one of the features of TOF-SIMS. However, degradation of the sample due to primary ion bombardment becomes problematic when the analysis area is small. Although polystyrene (PS) and polybutadiene (PB) separately show relatively distinct spectra, observation of their phase separation in PS/PB blends is difficult when the analysis area is small because degradation of both polymers and especially PS leads to disappearance of their characteristic peaks, resulting in low chemical image contrast. We therefore investigated the application of various forms of multivariate analysis (MVA) to the TOF-SIMS image data to improve the chemical image contrast. PCA, MCR, and the other forms of MVA provided improvement in contrast, but the images were still obscure and observation of phase separation remained difficult. Chemical derivatization using osmium tetroxide was also investigated, and found to give clear images of phase separation in the PS/PB blend. In quantitative determinations with MVA and chemical derivatization, PLS demonstrated the best predictive capability and chemical derivatization resulted in large deviations from both the bulk chemical composition and the determinations with MVA, particularly in regions of low PB content.

  20. Oxygen reduction reaction over silver particles with various morphologies and surface chemical states

    Science.gov (United States)

    Ohyama, Junya; Okata, Yui; Watabe, Noriyuki; Katagiri, Makoto; Nakamura, Ayaka; Arikawa, Hidekazu; Shimizu, Ken-ichi; Takeguchi, Tatsuya; Ueda, Wataru; Satsuma, Atsushi

    2014-01-01

    The oxygen reduction reaction (ORR) in an alkaline solution was carried out using Ag powders having various particle morphologies and surface chemical states (Size: ca. 40-110 nm in crystalline size. Shape: spherical, worm like, and angular. Surface: smooth with easily reduced AgOx, defective with AgOx, and Ag2CO3 surface layer). The various Ag powders were well characterized by X-ray diffraction, X-ray photoelectron spectroscopy, N2 adsorption, scanning electron microscopy, Raman spectroscopy, cyclic voltammetry, and stripping voltammetry of underpotential-deposited lead. Defective and oxidized surfaces enhanced the Ag active surface area during the ORR. The ORR activity was affected by the morphology and surface chemical state: Ag particles with defective and angular surfaces showed smaller electron exchange number between three and four but showed higher specific activity compared to Ag particles with smooth surfaces.

  1. State-Recovery Analysis of Spritz

    DEFF Research Database (Denmark)

    Ankele, Ralph; Kölbl, Stefan; Rechberger, Christian

    2015-01-01

    RC4 suffered from a range of plaintext-recovery attacks using statistical biases, which use substantial, albeit close-to-practical, amounts of known keystream in applications such as TLS or WEP/WPA. Spritz was recently proposed at the rump session of CRYPTO 2014 as a slower redesign of RC4...... the number of guessed values in our state recovery algorithm. Our third algorithm uses a probabilistic approach by considering the permutation table as probability distribution. All in all, rather than showing a weakness, our analysis supports the conjecture that compared to RC4, Spritz may also provide...

  2. Fractional State Space Analysis of Economic Systems

    Directory of Open Access Journals (Sweden)

    J. A. Tenreiro Machado

    2015-07-01

    Full Text Available This paper examines modern economic growth according to the multidimensional scaling (MDS method and state space portrait (SSP analysis. Electing GDP per capita as the main indicator for economic growth and prosperity, the long-run perspective from 1870 to 2010 identifies the main similarities among 34 world partners’ modern economic growth and exemplifies the historical waving mechanics of the largest world economy, the USA. MDS reveals two main clusters among the European countries and their old offshore territories, and SSP identifies the Great Depression as a mild challenge to the American global performance, when compared to the Second World War and the 2008 crisis.

  3. CHEMICALS

    CERN Multimedia

    Medical Service

    2002-01-01

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

  4. Quantitative chemical analysis of ocular melanosomes in the TEM.

    Science.gov (United States)

    Eibl, O; Schultheiss, S; Blitgen-Heinecke, P; Schraermeyer, U

    2006-01-01

    Melanosomes in retinal tissues of a human, monkey and rat were analyzed by EDX in the TEM. Samples were prepared by ultramicrotomy at different thicknesses. The material was mounted on Al grids and samples were analyzed in a Zeiss 912 TEM equipped with an Omega filter and EDX detector with ultrathin window. Melanosomes consist of C and O as main components, mole fractions are about 90 and 3-10 at.%, respectively, and small mole fraction ratios, between 2 and 0.1 at.%, of Na, Mg, K, Si, P, S, Cl, Ca. All elements were measured quantitatively by standardless EDX with high precision. Mole fractions of transition metals Fe, Cu and Zn were also measured. For Fe a mole fraction ratio of less than 0.1at.% was found and gives the melanin its paramagnetic properties. Its mole fraction is however close to or below the minimum detectable mass fraction of the used equipment. Only in the human eye and only in the retinal pigment epitelium (rpe) the mole fractions of Zn (0.1 at.% or 5000 microg/g) and Cu were clearly beyond the minimum detectable mass fraction. In the rat and monkey eye the mole fraction of Zn was at or below the minimum detectable mass fraction and could not be measured quantitatively. The obtained results yielded the chemical composition of the melanosomes in the choroidal tissue and the retinal pigment epitelium (rpe) of the three different species. The results of the chemical analysis are discussed by mole fraction correlation diagrams. Similarities and differences between the different species are outlined. Correlation behavior was found to hold over species, e.g. the Ca-O correlation. It indicates that Ca is bound to oxygen rich sites in the melanin. These are the first quantitative analyses of melanosomes by EDX reported so far. The quantitative chemical analysis should open a deeper understanding of the metabolic processes in the eye that are of central importance for the understanding of a large number of eye-related diseases. The chemical analysis also

  5. Application of Photocured Polymer Ion Selective Membranes for Solid-State Chemical Sensors

    Directory of Open Access Journals (Sweden)

    Natalia Abramova

    2015-06-01

    Full Text Available Application of conducting polymers with additional functional groups for a solid contact formation and photocurable membranes as sensitive elements of solid-state chemical sensors is discussed. Problems associated with application of UV-curable polymers for sensors are analyzed. A method of sensor fabrication using copolymerized conductive layer and sensitive membrane is presented and the proof of concept is confirmed by two examples of solid-contact electrodes for Ca ions and pH.

  6. Development of an Electrolyte CPA Equation of state for Applications in the Petroleum and Chemical Industries

    DEFF Research Database (Denmark)

    Maribo-Mogensen, Bjørn

    This thesis extends the Cubic Plus Association (CPA) equation of state (EoS) to handle mixtures containing ions from fully dissociated salts. The CPA EoS has during the past 18 years been applied to thermodynamic modeling of a wide range of industrially important chemicals, mainly in relation...... to provide sufficient driving forces for electrolytes towards the most polar phase. The static permittivity of the mixture was found to be the most important property; yet it was shown that the empirical models suggested by literature could lead to unphysical behavior of the equation of state. A new...

  7. Microbiological and chemical analysis of land snails commercialised in Sicily

    Directory of Open Access Journals (Sweden)

    Antonello Cicero

    2015-05-01

    Full Text Available In this study 160 samples of snails belonging to the species Helix aspersa maxima and Helix aspersa muller were examined for chemical and microbiological analysis. Samples came from Greece and Poland. Results showed mean concentration of cadmium (0.35±0.036 mg/kg and lead (0.05±0.013 mg/kg much higher than the limit of detection. Mercury levels in both species were not detected. Microbiological analysis revealed the absence of Salmonella spp. and Clostridium spp. in both examined species. E. coli and K. oxytoca were observed in Helix aspersa maxima and Helix aspersa muller. Furthermore, one case of fungi positivity in samples of Helix aspersa muller was found. The reported investigations highlight the need to create and adopt a reference legislation to protect the health of consumers.

  8. Chemical Analysis of Wastewater from Unconventional Drilling Operations

    Directory of Open Access Journals (Sweden)

    Jonathan B. Thacker

    2015-04-01

    Full Text Available Trillions of liters of wastewater from oil and gas extraction are generated annually in the US. The contribution from unconventional drilling operations (UDO, such as hydraulic fracturing, to this volume will likely continue to increase in the foreseeable future. The chemical content of wastewater from UDO varies with region, operator, and elapsed time after production begins. Detailed chemical analyses may be used to determine its content, select appropriate treatment options, and identify its source in cases of environmental contamination. In this study, one wastewater sample each from direct effluent, a disposal well, and a waste pit, all in West Texas, were analyzed by gas chromatography-mass spectrometry, inductively coupled plasma-optical emission spectroscopy, high performance liquid chromatography-high resolution mass spectrometry, high performance ion chromatography, total organic carbon/total nitrogen analysis, and pH and conductivity analysis. Several compounds known to compose hydraulic fracturing fluid were detected among two of the wastewater samples including 2-butoxyethanol, alkyl amines, and cocamide diethanolamines, toluene, and o-xylene. Due both to its quantity and quality, proper management of wastewater from UDO will be essential.

  9. Stochastic analysis of Chemical Reaction Networks using Linear Noise Approximation.

    Science.gov (United States)

    Cardelli, Luca; Kwiatkowska, Marta; Laurenti, Luca

    2016-11-01

    Stochastic evolution of Chemical Reactions Networks (CRNs) over time is usually analyzed through solving the Chemical Master Equation (CME) or performing extensive simulations. Analysing stochasticity is often needed, particularly when some molecules occur in low numbers. Unfortunately, both approaches become infeasible if the system is complex and/or it cannot be ensured that initial populations are small. We develop a probabilistic logic for CRNs that enables stochastic analysis of the evolution of populations of molecular species. We present an approximate model checking algorithm based on the Linear Noise Approximation (LNA) of the CME, whose computational complexity is independent of the population size of each species and polynomial in the number of different species. The algorithm requires the solution of first order polynomial differential equations. We prove that our approach is valid for any CRN close enough to the thermodynamical limit. However, we show on four case studies that it can still provide good approximation even for low molecule counts. Our approach enables rigorous analysis of CRNs that are not analyzable by solving the CME, but are far from the deterministic limit. Moreover, it can be used for a fast approximate stochastic characterization of a CRN.

  10. Ecological food web analysis for chemical risk assessment.

    Science.gov (United States)

    Preziosi, Damian V; Pastorok, Robert A

    2008-12-01

    Food web analysis can be a critical component of ecological risk assessment, yet it has received relatively little attention among risk assessors. Food web data are currently used in modeling bioaccumulation of toxic chemicals and, to a limited extent, in the determination of the ecological significance of risks. Achieving more realism in ecological risk assessments requires new analysis tools and models that incorporate accurate information on key receptors in a food web paradigm. Application of food web analysis in risk assessments demands consideration of: 1) different kinds of food webs; 2) definition of trophic guilds; 3) variation in food webs with habitat, space, and time; and 4) issues for basic sampling design and collection of dietary data. The different kinds of food webs include connectance webs, materials flow webs, and functional (or interaction) webs. These three kinds of webs play different roles throughout various phases of an ecological risk assessment, but risk assessors have failed to distinguish among web types. When modeling food webs, choices must be made regarding the level of complexity for the web, assignment of species to trophic guilds, selection of representative species for guilds, use of average diets, the characterization of variation among individuals or guild members within a web, and the spatial and temporal scales/dynamics of webs. Integrating exposure and effects data in ecological models for risk assessment of toxic chemicals relies on coupling food web analysis with bioaccumulation models (e.g., Gobas-type models for fish and their food webs), wildlife exposure models, dose-response models, and population dynamics models.

  11. Experiments on bifurcation of periodic states into tori for a periodically forced chemical oscillator

    Science.gov (United States)

    Vance, William; Ross, John

    1988-05-01

    We study experimentally continuous transitions from quasiperiodic to periodic states for a time-periodically forced chemical oscillator. The chemical reaction is the hydration of 2,3-epoxy-1-propanol, and is carried out in a continuous stirred tank reactor (CSTR). Periodic oscillatory states are observed to arise in the autonomous system through supercritical Hopf bifurcations as either the total flow rate or the cooling coil temperature is changed. Under conditions of oscillation for the autonomous system, small-amplitude periodic variation of the total flow rate generates an attracting two-torus from the stable limit cycle. From the experiments we determine the structure of the toroidal flow, stroboscopic phase portraits, and circle maps as a function of the forcing amplitude and period. A continuous transition from the quasiperiodic to a periodic state, in which the two-torus contracts to a closed curve (Neimark-Sacker torus bifurcation), is observed as the forcing amplitude is increased at a constant forcing period, or as the forcing period is changed at a constant moderate forcing amplitude. Qualitative theoretical predictions compare well with the experimental observations. This paper presents the first experimental observation of a Neimark-Sacker torus bifurcation in a forced chemical oscillator system, and relates the bifurcation diagram of the unforced system to that of the forced system.

  12. Steady-state equation of water vapor sorption for CaCl2-based chemical sorbents and its application

    Science.gov (United States)

    Zhang, Haiquan; Yuan, Yanping; Sun, Qingrong; Cao, Xiaoling; Sun, Liangliang

    2016-09-01

    Green CaCl2-based chemical sorbent has been widely used in sorption refrigeration, air purification and air desiccation. Methods to improve the sorption rate have been extensively investigated, but the corresponding theoretical formulations have not been reported. In this paper, a sorption system of solid-liquid coexistence is established based on the hypothesis of steady-state sorption. The combination of theoretical analysis and experimental results indicates that the system can be described by steady-state sorption process. The steady-state sorption equation, μ = (η - γT) , was obtained in consideration of humidity, temperature and the surface area. Based on engineering applications and this equation, two methods including an increase of specific surface area and adjustment of the critical relative humidity (γ) for chemical sorbents, have been proposed to increase the sorption rate. The results indicate that the CaCl2/CNTs composite with a large specific surface area can be obtained by coating CaCl2 powder on the surface of carbon nanotubes (CNTs). The composite reached sorption equilibrium within only 4 h, and the sorption capacity was improved by 75% compared with pure CaCl2 powder. Furthermore, the addition of NaCl powder to saturated CaCl2 solution could significantly lower the solution’s γ. The sorption rate was improved by 30% under the same environment.

  13. Steady-state equation of water vapor sorption for CaCl2-based chemical sorbents and its application

    Science.gov (United States)

    Zhang, Haiquan; Yuan, Yanping; Sun, Qingrong; Cao, Xiaoling; Sun, Liangliang

    2016-01-01

    Green CaCl2-based chemical sorbent has been widely used in sorption refrigeration, air purification and air desiccation. Methods to improve the sorption rate have been extensively investigated, but the corresponding theoretical formulations have not been reported. In this paper, a sorption system of solid-liquid coexistence is established based on the hypothesis of steady-state sorption. The combination of theoretical analysis and experimental results indicates that the system can be described by steady-state sorption process. The steady-state sorption equation, μ = (η − γT) , was obtained in consideration of humidity, temperature and the surface area. Based on engineering applications and this equation, two methods including an increase of specific surface area and adjustment of the critical relative humidity (γ) for chemical sorbents, have been proposed to increase the sorption rate. The results indicate that the CaCl2/CNTs composite with a large specific surface area can be obtained by coating CaCl2 powder on the surface of carbon nanotubes (CNTs). The composite reached sorption equilibrium within only 4 h, and the sorption capacity was improved by 75% compared with pure CaCl2 powder. Furthermore, the addition of NaCl powder to saturated CaCl2 solution could significantly lower the solution’s γ. The sorption rate was improved by 30% under the same environment. PMID:27682811

  14. Octafluorodirhenate(III) Revisited: Solid-State Preparation, Characterization, and Multiconfigurational Quantum Chemical Calculations

    Energy Technology Data Exchange (ETDEWEB)

    Mariappan Balasekaran, Samundeeswari; Todorova, Tanya K.; Pham, Chien Thang; Hartmann, Thomas; Abram, Ulrich; Sattelberger, Alfred P.; Poineau, Frederic

    2016-06-06

    A simple method for the high-yield preparation of (NH4)2[Re2F8]· 2H2O has been developed that involves the reaction of (n-Bu4N)2[Re2Cl8] with molten ammonium bifluoride (NH4HF2). Using this method, the new salt [NH4]2[Re2F8]·2H2O was prepared in ~90% yield. The product was characterized in solution by ultraviolet-visible light (UV-vis) and 19F nuclear magnetic resonance (19F NMR) spectroscopies and in the solid-state by elemental analysis, powder X-ray diffraction (XRD), and infrared (IR) spectroscopy. Multiconfigurational CASSCF/CASPT2 quantum chemical calculations were performed to investigate the molecular and electronic structure, as well as the electronic absorption spectrum of the [Re2F8] 2- anion. The metal-metal bonding in the Re2 6+ unit was quantified in terms of effective bond order (EBO) and compared to that of its [Re2Cl8] 2- and [Re2Br8] 2- analogues.

  15. Extending coherent state transforms to Clifford analysis

    Science.gov (United States)

    Kirwin, William D.; Mourão, José; Nunes, João P.; Qian, Tao

    2016-10-01

    Segal-Bargmann coherent state transforms can be viewed as unitary maps from L2 spaces of functions (or sections of an appropriate line bundle) on a manifold X to spaces of square integrable holomorphic functions (or sections) on Xℂ. It is natural to consider higher dimensional extensions of X based on Clifford algebras as they could be useful in studying quantum systems with internal, discrete, degrees of freedom corresponding to nonzero spins. Notice that the extensions of X based on the Grassmann algebra appear naturally in the study of supersymmetric quantum mechanics. In Clifford analysis, the zero mass Dirac equation provides a natural generalization of the Cauchy-Riemann conditions of complex analysis and leads to monogenic functions. For the simplest but already quite interesting case of X = ℝ, we introduce two extensions of the Segal-Bargmann coherent state transform from L2(ℝ, dx) ⊗ ℝm to Hilbert spaces of slice monogenic and axial monogenic functions and study their properties. These two transforms are related by the dual Radon transform. Representation theoretic and quantum mechanical aspects of the new representations are studied.

  16. Do provisions to advance chemical facility safety also advance chemical facility security? An analysis of possible synergies

    DEFF Research Database (Denmark)

    Hedlund, Frank Huess

    2012-01-01

    endanger neighbouring populated areas. Second, facilities where high-risk chemicals are present could present opportunities for theft. The concern is that relatively small amounts of highly toxic chemicals could be taken to another location selected for higher impact. The Directive on European Critical......The European Commission has launched a study on the applicability of existing chemical industry safety provisions to enhancing security of chemical facilities covering the situation in 18 EU Member States. This paper reports some preliminary analytical findings regarding the extent to which...... exist at the mitigation level. At the strategic policy level, synergies are obvious. The security of chemical facilities is important. First, facilities with large inventories of toxic materials could be attractive targets for terrorists. The concern is sabotage causing an intentional release that could...

  17. Emergence of a super-synchronized mobbing state in a large population of coupled chemical oscillators

    Science.gov (United States)

    Ghoshal, Gourab; Muñuzuri, Alberto P.; Pérez-Mercader, Juan

    2016-01-01

    Oscillatory phenomena are ubiquitous in Nature. The ability of a large population of coupled oscillators to synchronize constitutes an important mechanism to express information and establish communication among members. To understand such phenomena, models and experimental realizations of globally coupled oscillators have proven to be invaluable in settings as varied as chemical, biological and physical systems. A variety of rich dynamical behavior has been uncovered, although usually in the context of a single state of synchronization or lack thereof. Through the experimental and numerical study of a large population of discrete chemical oscillators, here we report on the unexpected discovery of a new phenomenon revealing the existence of dynamically distinct synchronized states reflecting different degrees of communication. Specifically, we discover a novel large-amplitude super-synchronized state separated from the conventionally reported synchronized and quiescent states through an unusual sharp jump transition when sampling the strong coupling limit. Our results assume significance for further elucidating globally coherent phenomena, such as in neuropathologies, bacterial cell colonies, social systems and semiconductor lasers.

  18. ANALYSIS OF THERMAL-CHEMICAL CHARACTERISTICS OF BIOMASS ENERGY PELLETS

    Directory of Open Access Journals (Sweden)

    Zorica Gluvakov

    2014-09-01

    Full Text Available In modern life conditions, when emphasis is on environmental protection and sustainable development, fuels produced from biomass are increasingly gaining in importance, and it is necessary to consider the quality of end products obtained from biomass. Based on the existing European standards, collected literature and existing laboratory methods, this paper presents results of testing individual thermal - chemical properties of biomass energy pellets after extrusion and cooling the compressed material. Analysing samples based on standard methods, data were obtained on the basis of which individual thermal-chemical properties of pellets were estimated. Comparing the obtained results with the standards and literature sources, it can be said that moisture content, ash content and calorific values are the most important parameters for quality analysis which decide on applicability and use-value of biomass energy pellets, as biofuel. This paper also shows the impact of biofuels on the quality of environmental protection. The conclusion provides a clear statement of quality of biomass energy pellets.

  19. Computational analysis of RNA structures with chemical probing data.

    Science.gov (United States)

    Ge, Ping; Zhang, Shaojie

    2015-06-01

    RNAs play various roles, not only as the genetic codes to synthesize proteins, but also as the direct participants of biological functions determined by their underlying high-order structures. Although many computational methods have been proposed for analyzing RNA structures, their accuracy and efficiency are limited, especially when applied to the large RNAs and the genome-wide data sets. Recently, advances in parallel sequencing and high-throughput chemical probing technologies have prompted the development of numerous new algorithms, which can incorporate the auxiliary structural information obtained from those experiments. Their potential has been revealed by the secondary structure prediction of ribosomal RNAs and the genome-wide ncRNA function annotation. In this review, the existing probing-directed computational methods for RNA secondary and tertiary structure analysis are discussed.

  20. Method for fractional solid-waste sampling and chemical analysis

    DEFF Research Database (Denmark)

    Riber, Christian; Rodushkin, I.; Spliid, Henrik

    2007-01-01

    to repeated particle-size reduction, mixing, and mass reduction until a sufficiently small but representative sample was obtained for digestion prior to chemical analysis. The waste-fraction samples were digested according to their properties for maximum recognition of all the studied substances. By combining...... four subsampling methods and five digestion methods, paying attention to the heterogeneity and the material characteristics of the waste fractions, it was possible to determine 61 substances with low detection limits, reasonable variance, and high accuracy. For most of the substances of environmental...... concern, the waste-sample concentrations were above the detection limit (e.g. Cd gt; 0.001 mg kg-1, Cr gt; 0.01 mg kg-1, Hg gt; 0.002 mg kg-1, Pb gt; 0.005 mg kg-1). The variance was in the range of 5-100%, depending on material fraction and substance as documented by repeated sampling of two highly...

  1. Chemical gas analyzers for proximate analysis of mine atmosphere

    Energy Technology Data Exchange (ETDEWEB)

    Pochenkova, T.K.; Klassovskaya, N.A.; Zlenko, A.G.; Gus' kova, A.N. (Vsesoyuznyi Nauchno-Issledovatel' skii Institut Gornogo Dela, Donetsk (Ukraine))

    1992-09-01

    Describes a series of chemical gas analyzers developed by the VNIIGD institute for proximate analysis of mine atmosphere in coal mines. The new GKh-4, GKh-5, GKh-6, GKh CO-5 use detector tubes for carbon monoxide and dioxide, nitrogen oxides, sulfur dioxide, oxygen and hydrogen sulfide. These devices allow miners to determine gas concentrations in the mine atmosphere in less than 4 minutes with an accuracy of +/-25%. The series is now complemented by the GKh-M CH[sub 2]O-0.004 gas analyzer for measuring formaldehyde content in mine air during mine rescue operations conducted with the use of carbamide-formaldehyde resins. Key technical data on the gas analyzers are given.

  2. Structural Analysis Of Alfa Fibers After Chemical Treatment

    Directory of Open Access Journals (Sweden)

    Zakaria Mouallif

    2015-02-01

    Full Text Available Nowadays, natural fibers are used as reinforcement in composite materials. The Alfa fibers have undergone an alkaline treatment with sodium hydroxide NaOH at a concentration of 10%, during an immersion period of two days. After drying, the Fourier transform infrared spectroscopy by attenuated total reflection (FTIR-ATR and X-ray diffraction (XRD were used for the analysis of the chemical properties of these fibers which were extracted from the plant Alfa of the region Al Haouz (Morocco in order to study the modifications resulting from the alkaline treatment. The results proved the presence of the cellulose, with an increase in its proportion in those fibers which have undergone an alkaline treatment with NaOH, the presence of lignin and pectin, as well as their disappearance after the alkaline extraction.

  3. Advances in the Chemical Analysis and Biological Activities of Chuanxiong

    Directory of Open Access Journals (Sweden)

    Jin-Ao Duan

    2012-09-01

    Full Text Available Chuanxiong Rhizoma (Chuan-Xiong, CX, the dried rhizome of Ligusticum chuanxiong Hort. (Umbelliferae, is one of the most popular plant medicines in the World. Modern research indicates that organic acids, phthalides, alkaloids, polysaccharides, ceramides and cerebrosides are main components responsible for the bioactivities and properties of CX. Because of its complex constituents, multidisciplinary techniques are needed to validate the analytical methods that support CX’s use worldwide. In the past two decades, rapid development of technology has advanced many aspects of CX research. The aim of this review is to illustrate the recent advances in the chemical analysis and biological activities of CX, and to highlight new applications and challenges. Emphasis is placed on recent trends and emerging techniques.

  4. Prediction of chemical, physical and sensory data from process parameters for frozen cod using multivariate analysis

    DEFF Research Database (Denmark)

    Bechmann, Iben Ellegaard; Jensen, H.S.; Bøknæs, Niels

    1998-01-01

    Physical, chemical and sensory quality parameters were determined for 115 cod (Gadus morhua) samples stored under varying frozen storage conditions. Five different process parameters (period of frozen storage, frozen storage. temperature, place of catch, season for catching and state of rigor) were...... varied systematically at two levels. The data obtained were evaluated using the multivariate methods, principal component analysis (PCA) and partial least squares (PLS) regression. The PCA models were used to identify which process parameters were actually most important for the quality of the frozen cod....... PLS models that were able to predict the physical, chemical and sensory quality parameters from the process parameters of the frozen raw material were generated. The prediction abilities of the PLS models were good enough to give reasonable results even when the process parameters were characterised...

  5. Physico-Chemical Analysis of Selected Groundwater Samples of Inkollu Mandal, Prakasam District, Andhra Pradesh, India

    Directory of Open Access Journals (Sweden)

    G. Arun Kumar

    2015-04-01

    Full Text Available Physico-chemical parameters of groundwater quality based on Physic-chemical parameters at Inkollu mandal, Prakasam district, Andhra Pradesh, India have been taken up to evaluate its suitability for Drinking purpose. Nine ground water samples were collected from different places of Inkollu mandal of Prakasam district. The quality analysis has been made through the pH, EC, TDS, Total Hardness, Sodium, Potassium, Calcium, Magnesium, Chloride, Sulphate, Nitrate, Fluoride and Iron. By observing the results, it was shown that the parameters from the water samples were compared with WHO (World Health Organization and BIS (Bureau of Indian Standards, USPH (United state Public health for ground water .The results revealed that some parameters were in high concentration and quality of the potable water has deteriorated to a large extent at some sampling locations.

  6. ANALYSIS OF SAMPLES FROM TANK 6F CHEMICAL CLEANING

    Energy Technology Data Exchange (ETDEWEB)

    Poirier, M.; Fink, S.

    2010-02-02

    Savannah River Remediation (SRR) is preparing Tank 6F for closure. The first step in preparing the tank for closure is mechanical sludge removal. In mechanical sludge removal, personnel add liquid (e.g., inhibited water or supernate salt solution) to the tank to form a slurry. They mix the liquid and sludge with pumps, and transfer the slurry to another tank for further processing. Mechanical sludge removal effectively removes the bulk of the sludge from a tank, but is not able to remove all of the sludge. In Tank 6F, SRR estimated a sludge heel of 5,984 gallons remained after mechanical sludge removal. To remove this sludge heel, SRR performed chemical cleaning. The chemical cleaning included two oxalic acid strikes, a spray wash, and a water wash. SRR conducted the first oxalic acid strike as follows. Personnel added 110,830 gallons of 8 wt % oxalic acid to Tank 6F and mixed the contents of Tank 6F with two submersible mixer pumps (SMPs) for approximately four days. Following the mixing, they transferred 115,903 gallons of Tank 6F material to Tank 7F. The SMPs were operating when the transfer started and were shut down approximately five hours after the transfer started. SRR collected a sample of the liquid from Tank 6F and submitted it to SRNL for analysis. Mapping of the tank following the transfer indicated that 2,400 gallons of solids remained in the tank. SRR conducted the second oxalic acid strike as follows. Personnel added 28,881 gallons of 8 wt % oxalic acid to Tank 6F. Following the acid addition, they visually inspected the tank and transferred 32,247 gallons of Tank 6F material to Tank 7F. SRR collected a sample of the liquid from Tank 6F and submitted it to SRNL for analysis. Mapping of the tank following the transfer indicated that 3,248 gallons of solids remained in the tank. Following the oxalic acid strikes, SRR performed Spray Washing with oxalic acid to remove waste collected on internal structures, cooling coils, tank top internals, and tank

  7. LIQUIDITY ANALYSIS OF STATE BANK OF INDIA

    Directory of Open Access Journals (Sweden)

    Kumar Gandhi R

    2011-12-01

    Full Text Available Modern customer has a high demand for quality of service than he/she had before. There is an urgent need for improving the customer service levels currently provided in the banking industry. Banks need to understand, foresee, the needs and expected levels of customer support which the customer expects when he/she steps into the branch and strive to stand up and excel in providing the service and making banking a truly delightful experience. The banker should change his/her agenda from Customer Satisfaction to Customer delight and then march towards Customer Ecstasy. This will be possible by maintaining the financial soundness of the firm. In this connection it has been given importance through this study. Since most of the Banking slightly deviate into the other areas like insurance, financial services and modern banking services such as Advisory services, Agent for receivables, custodian, instant loan provider, Forfeiter services and factoring services. A conscious attempt has been made to analysis the liquidity of state bank of India (SBI. The present study aimed to understand the financial soundness of the bank, the ratio analysis taken as tool. In this research work the secondary data mainly used, it has been collected in the form of the company manuals, Balance sheets and other documents. The data analyzed by some of the statistical tools such as ANOVA test and Multi variate test is used to analyze the interferences about the operating efficiency.

  8. Biomass Feedstock Availability in the United States: 1999 State Level Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Walsh, Marie E. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Perlack, Robert L. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Turhollow, Anthony [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); de la Torre Ugarte, Daniel [Univ. of Tennessee, Knoxville, TN (United States); Becker, Denny A. [Science Applications International Corporation, Oak Ridge, TN (United States); Graham, Robin L. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Slinsky, Stephen E. [Univ. of Tennessee, Knoxville, TN (United States); Ray, Daryll E. [Univ. of Tennessee, Knoxville, TN (United States)

    2000-01-01

    Interest in using biomass feedstocks to produce power, liquid fuels, and chemicals in the U.S. is increasing. Central to determining the potential for these industries to develop is an understanding of the location, quantities, and prices of biomass resources. This paper describes the methodology used to estimate biomass quantities and prices for each state in the continental United States.

  9. (31)P Solid-State NMR study of the chemical setting process of a dual-paste injectable brushite cements.

    Science.gov (United States)

    Legrand, A P; Sfihi, H; Lequeux, N; Lemaître, J

    2009-10-01

    The composition and evolution of a brushite-type calcium phosphate cement was investigated by Solid-State NMR and X-ray during the setting process. The cement is obtained by mixing beta-tricalcium phosphate [Ca(3)(PO(4))(2), beta-TCP] and monocalcium phosphate monohydrate [Ca(H(2)PO(4))(2).H(2)O, MCPM] in presence of water, with formation of dicalcium phosphate dihydrate or brushite [CaHPO(2).2H(2)O, DCPD]. Analysis of the initial beta-TCP paste has shown the presence of beta-calcium pyrophosphate [Ca(2)P(2)O(7), beta-CPy] and that of the initial MCPM a mixture of MCPM and dicalcium phosphate [CaHPO(4), DCP]. Follow-up of the chemical composition by (31)P Solid-State NMR enables to show that the chemical setting process appeared to reach an end after 20 min. The constant composition observed at the end of the process was similarly determined.

  10. Advances in Mid-Infrared Spectroscopy for Chemical Analysis

    Science.gov (United States)

    Haas, Julian; Mizaikoff, Boris

    2016-06-01

    Infrared spectroscopy in the 3-20 μm spectral window has evolved from a routine laboratory technique into a state-of-the-art spectroscopy and sensing tool by benefitting from recent progress in increasingly sophisticated spectra acquisition techniques and advanced materials for generating, guiding, and detecting mid-infrared (MIR) radiation. Today, MIR spectroscopy provides molecular information with trace to ultratrace sensitivity, fast data acquisition rates, and high spectral resolution catering to demanding applications in bioanalytics, for example, and to improved routine analysis. In addition to advances in miniaturized device technology without sacrificing analytical performance, selected innovative applications for MIR spectroscopy ranging from process analysis to biotechnology and medical diagnostics are highlighted in this review.

  11. Understanding the finite state projection and related methods for solving the chemical master equation

    Science.gov (United States)

    Dinh, Khanh N.; Sidje, Roger B.

    2016-06-01

    The finite state projection (FSP) method has enabled us to solve the chemical master equation of some biological models that were considered out of reach not long ago. Since the original FSP method, much effort has gone into transforming it into an adaptive time-stepping algorithm as well as studying its accuracy. Some of the improvements include the multiple time interval FSP, the sliding windows, and most notably the Krylov-FSP approach. Our goal in this tutorial is to give the reader an overview of the current methods that build on the FSP.

  12. Ensemble velocity of non-processive molecular motors with multiple chemical states

    CERN Document Server

    Vilfan, Andrej

    2014-01-01

    We study the ensemble velocity of non-processive motor proteins, described with multiple chemical states. In particular, we discuss the velocity as a function of ATP concentration. Even a simple model which neglects the strain-dependence of transition rates, reverse transition rates and nonlinearities in the elasticity can show interesting functional dependencies, which deviate significantly from the frequently assumed Michaelis-Menten form. We discuss how the oder of events in the duty cycle can be inferred from the measured dependence. The model also predicts the possibility of velocity reversal at a certain ATP concentration if the duty cycle contains several conformational changes of opposite directionalities.

  13. Behaviors of optical and chemical state of Nb+ implanted sapphire after annealing

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The behavior of the radiation damage of sapphire crystal, produced by implantation with 380 keV Nb+ ion followed by annealing in a series of steps from 500 to 1100℃C at reducing atmosphere, was investigated in optical absorption and XPS measurements. It is found that the implanted niobium in sapphire is in different local environments with different chemical states after the annealing. The changes in optical density (OD) from the bands, based on the well known F-type centers, show that the annealing behavior of the radiation damage may be divided into different stages due to different mechanisms.

  14. Meta-Analysis of the Chemical and Non-Chemical Stressors Affecting Childhood Obesity

    Science.gov (United States)

    Worldwide, approximately 42 million children under the age of 5 years are considered overweight or obese. While much research has focused on individual behaviors impacting obesity, little research has emphasized the complex interactions of numerous chemical and non-chemical stres...

  15. Flow Injection Analysis and Liquid Chromatography for Multifunctional Chemical Analysis (MCA) Systems

    Science.gov (United States)

    Mayo, Ana V.; Loegel, Thomas N.; Bretz, Stacey Lowery; Danielson, Neil D.

    2013-01-01

    The large class sizes of first-year chemistry labs makes it challenging to provide students with hands-on access to instrumentation because the number of students typically far exceeds the number of research-grade instruments available to collect data. Multifunctional chemical analysis (MCA) systems provide a viable alternative for large-scale…

  16. ACTINIDE REMOVAL PROCESS SAMPLE ANALYSIS, CHEMICAL MODELING, AND FILTRATION EVALUATION

    Energy Technology Data Exchange (ETDEWEB)

    Martino, C.; Herman, D.; Pike, J.; Peters, T.

    2014-06-05

    Filtration within the Actinide Removal Process (ARP) currently limits the throughput in interim salt processing at the Savannah River Site. In this process, batches of salt solution with Monosodium Titanate (MST) sorbent are concentrated by crossflow filtration. The filtrate is subsequently processed to remove cesium in the Modular Caustic Side Solvent Extraction Unit (MCU) followed by disposal in saltstone grout. The concentrated MST slurry is washed and sent to the Defense Waste Processing Facility (DWPF) for vitrification. During recent ARP processing, there has been a degradation of filter performance manifested as the inability to maintain high filtrate flux throughout a multi-batch cycle. The objectives of this effort were to characterize the feed streams, to determine if solids (in addition to MST) are precipitating and causing the degraded performance of the filters, and to assess the particle size and rheological data to address potential filtration impacts. Equilibrium modelling with OLI Analyzer{sup TM} and OLI ESP{sup TM} was performed to determine chemical components at risk of precipitation and to simulate the ARP process. The performance of ARP filtration was evaluated to review potential causes of the observed filter behavior. Task activities for this study included extensive physical and chemical analysis of samples from the Late Wash Pump Tank (LWPT) and the Late Wash Hold Tank (LWHT) within ARP as well as samples of the tank farm feed from Tank 49H. The samples from the LWPT and LWHT were obtained from several stages of processing of Salt Batch 6D, Cycle 6, Batch 16.

  17. Avogadro: an advanced semantic chemical editor, visualization, and analysis platform

    Directory of Open Access Journals (Sweden)

    Hanwell Marcus D

    2012-08-01

    Full Text Available Abstract Background The Avogadro project has developed an advanced molecule editor and visualizer designed for cross-platform use in computational chemistry, molecular modeling, bioinformatics, materials science, and related areas. It offers flexible, high quality rendering, and a powerful plugin architecture. Typical uses include building molecular structures, formatting input files, and analyzing output of a wide variety of computational chemistry packages. By using the CML file format as its native document type, Avogadro seeks to enhance the semantic accessibility of chemical data types. Results The work presented here details the Avogadro library, which is a framework providing a code library and application programming interface (API with three-dimensional visualization capabilities; and has direct applications to research and education in the fields of chemistry, physics, materials science, and biology. The Avogadro application provides a rich graphical interface using dynamically loaded plugins through the library itself. The application and library can each be extended by implementing a plugin module in C++ or Python to explore different visualization techniques, build/manipulate molecular structures, and interact with other programs. We describe some example extensions, one which uses a genetic algorithm to find stable crystal structures, and one which interfaces with the PackMol program to create packed, solvated structures for molecular dynamics simulations. The 1.0 release series of Avogadro is the main focus of the results discussed here. Conclusions Avogadro offers a semantic chemical builder and platform for visualization and analysis. For users, it offers an easy-to-use builder, integrated support for downloading from common databases such as PubChem and the Protein Data Bank, extracting chemical data from a wide variety of formats, including computational chemistry output, and native, semantic support for the CML file format

  18. Chemical analysis of superconducting phase in K-doped picene

    Science.gov (United States)

    Kambe, Takashi; Nishiyama, Saki; Nguyen, Huyen L. T.; Terao, Takahiro; Izumi, Masanari; Sakai, Yusuke; Zheng, Lu; Goto, Hidenori; Itoh, Yugo; Onji, Taiki; Kobayashi, Tatsuo C.; Sugino, Hisako; Gohda, Shin; Okamoto, Hideki; Kubozono, Yoshihiro

    2016-11-01

    Potassium-doped picene (K3.0picene) with a superconducting transition temperature (T C) as high as 14 K at ambient pressure has been prepared using an annealing technique. The shielding fraction of this sample was 5.4% at 0 GPa. The T C showed a positive pressure-dependence and reached 19 K at 1.13 GPa. The shielding fraction also reached 18.5%. To investigate the chemical composition and the state of the picene skeleton in the superconducting sample, we used energy-dispersive x-ray (EDX) spectroscopy, MALDI-time-of-flight (MALDI-TOF) mass spectroscopy and x-ray diffraction (XRD). Both EDX and MALDI-TOF indicated no contamination with materials other than K-doped picene or K-doped picene fragments, and supported the preservation of the picene skeleton. However, it was also found that a magnetic K-doped picene sample consisted mainly of picene fragments or K-doped picene fragments. Thus, removal of the component contributing the magnetic quality to a superconducting sample should enhance the volume fraction.

  19. Analysis of physical and chemical parameters of bottled drinking water.

    Science.gov (United States)

    Mahajan, Rakesh Kumar; Walia, T P S; Lark, B S; Sumanjit

    2006-04-01

    Seventeen different brands of bottled drinking water, collected from different retail shops in Amritsar, were analyzed for different physical and chemical parameters to ascertain their compliability with the prescribed/recommended limits of the World Heath Organization (WHO) and the United States Environmental Protection Agency (USEPA). It was found that the majority of the brands tested were over-treated. Lower values of hardness, total dissolved solids (TDS) and conductance than the prescribed limits of WHO showed that water was deficient in essential minerals. Minerals like magnesium, potassium, calcium and fluoride were present in some cases in such a low concentration that water seemed to be as good as distilled water. Samples showing fluoride lesser than 0.5 mg/l warranted additional sources of fluoride for the people consuming only bottled water for drinking purposes. Zero values for chlorine demand as shown by all the bottled water samples showed that water samples were safe from micro-organisms. In case of heavy metals, only lead had been found to be greater than the limit of 0.015 mg/l as prescribed by WHO and USEPA, in seven out of 17 samples. Lead even at such a low concentration can pose a great health hazard.

  20. THE IMPACT OF REDUCED AGRICULTURAL CHEMICAL USE ON FOOD: A REVIEW OF THE LITERATURE FOR THE UNITED STATES

    OpenAIRE

    Senauer, Benjamin

    1993-01-01

    Concerns about food safety and environmental quality have increased in recent years. Consumers are particularly concerned about the health risks posed by pesticide residues in food and the environmental impact of agricultural chemicals. These concerns have stimulated a considerable amount of recent research to assess the effects of reduced agricultural chemical use. This paper focuses on the research in the United States which has examined the impact of reduced agricultural chemical use on fo...

  1. Chemical composition of sage (Salvia officinalis L. essential oil from the Rio de Janeiro State (Brazil

    Directory of Open Access Journals (Sweden)

    A. Porte

    2013-01-01

    Full Text Available The purpose of this study was to investigate the chemical composition of the essential oil from fresh leaves of sage (Salvia officinalis L. from Petrópolis, Rio de Janeiro State, for international trade. The oil was isolated by hydrodistillation in a Clevenger-type apparatus and analyzed through a combination of GC-FID and GC-MS. The yield was 2.3 % on dry basis. Forty-seven constituents were identified according to their chromatographic retention indices and mass spectra, corresponding to 94.90 % of the compounds present. The major constituents of the oil were α-thujone (40.90 %, camphor (26.12 %, α-pinene (5.85 % and β-thujone (5.62 %. The essential oil studied was similar to those found in several European countries and can be a valuable product for the small farmers from the Petrópolis region in Rio de Janeiro State.

  2. Quantum chemical computations, vibrational spectroscopic analysis and antimicrobial studies of 2,3-Pyrazinedicarboxylic acid.

    Science.gov (United States)

    Beaula, T Joselin; Packiavathi, A; Manimaran, D; Joe, I Hubert; Rastogi, V K; Jothy, V Bena

    2015-03-05

    Density Functional Theory (DFT) calculations at B3PW91 level with 6-311G (d) basis sets were carried out for 2,3-Pyrazinedicarboxylic acid (PDCA) to analyze in detail the equilibrium geometries and vibrational spectra. Calculations reveal that the optimized geometry closely resembles the experimental XRD data. Vibrational spectra were analyzed on the basis of potential energy distribution (PED) of each vibrational mode, which provides quantitative as well as qualitative interpretation of IR and Raman spectra. Information about size, shape, charge density distribution and site of chemical reactivity of the molecule were obtained by mapping electron density isosurface with the electrostatic potential surface (ESP). Based on optimized ground state geometries, NBO analysis was performed to study donor-acceptor (bond-antibond) interactions. TD-DFT analysis was also performed to calculate energies, oscillator strength of electronic singlet-singlet transitions and the absorption wavelengths. The (13)C and (1)H nuclear magnetic resonance (NMR) chemical shifts of the molecule in the ground state were calculated by gauge independent atomic orbital (GIAO) method and compared with the experimental values. PDCA was screened for its antimicrobial activity and found to exhibit antifungal and antibacterial effects. Molecular docking was also performed for the different receptors.

  3. ASAP: An Extensible Platform for State Space Analysis

    DEFF Research Database (Denmark)

    Westergaard, Michael; Evangelista, Sami; Kristensen, Lars Michael

    2009-01-01

    The ASCoVeCo State space Analysis Platform (ASAP) is a tool for performing explicit state space analysis of coloured Petri nets (CPNs) and other formalisms. ASAP supports a wide range of state space reduction techniques and is intended to be easy to extend and to use, making it a suitable tool...

  4. Análise de agrupamento, com base na composição físico-química, de amostras de méis produzidos por Apis mellifera L. no Estado de São Paulo Cluster analysis, with basis in physico-chemical composition, of samples of honey produced by Apis mellifera L. in São Paulo State

    Directory of Open Access Journals (Sweden)

    Luís Carlos Marchini

    2005-03-01

    Full Text Available A composição do mel depende, basicamente, da composição do néctar de cada espécie vegetal produtora, conferindo-lhe características específicas enquanto que as condições climáticas e o manejo do apicultor têm influência menor sobre essas características. A presente pesquisa, desenvolvida com amostras de méis de Apis mellifera coletadas diretamente dos produtores de 84 municípios do Estado de São Paulo teve o objetivo de verificar, com base em características físico-químicas, como se agrupam as amostras de méis silvestres e de eucaliptos. Dentre as 121 amostras de méis analisadas as de eucaliptos e as silvestres formam grupos distintos quanto aos caracteres físico-químicos, o que confirma que a origem floral interfere decisivamente nas características dos méis. Pela análise dos componentes principais, pode-se verificar que os caracteres que mais influenciaram no agrupamentos das amostras de méis foram condutividade elétrica e quantidade de K, no eixo X e índice de formol e umidade, no eixo Y.The honey composition depends, basically, of the nectar composition of each vegetal species. This composition confer to it specific characteristics while that the climatic conditions and the beekeeper handling have lesser influence on these features. The present research, developed with samples of Apis mellifera honeys, collected directly of the producers from 84 locations of the State of São Paulo, Brazil, had the objective of verifying, on the basis of physico-chemical characteristics, as the samples of wild and Eucalyptus honeys are grouped. Amongst the 121 samples analyzed the wild and Eucalyptus honeys form distinct groups with basis of the physico-chemical characteristics, what confirms that the floral origin intervenes decisively with the honey characteristics. For the analysis of the main components, it can be verified that the characters that had more influenced in the groupings of the honey samples were the electric

  5. State of the Climate - Global Analysis

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The State of the Climate is a collection of periodic summaries recapping climate-related occurrences on both a global and national scale. The State of the Climate...

  6. A Review of Equation of State Models, Chemical Equilibrium Calculations and CERV Code Requirements for SHS Detonation Modelling

    Science.gov (United States)

    2009-10-01

    Beattie - Bridgeman Virial expansion The above equations are suitable for moderate pressures and are usually based on either empirical constants...CR 2010-013 October 2009 A Review of Equation of State Models, Chemical Equilibrium Calculations and CERV Code Requirements for SHS Detonation...Defence R&D Canada. A Review of Equation of State Models, Chemical Equilibrium Calculations and CERV Code Requirements for SHS Detonation

  7. STUDIES ON THE CHEMICAL STRUCTURES OF ACTIVATED CARBON FIBERS BY SOLID STATE NMR

    Institute of Scientific and Technical Information of China (English)

    FURuowen; HuangWenqiang; 等

    1999-01-01

    The solid state C13-NMR spectra of different ACFs from various precursor fibers were recorded in this paper,The effects of activation conditions on chemical structures of ACFs,as well as the changes of chemical structures during carbonization and redox reaction were inverstigated by NMR technique,At same time,the soild state P31-NMR spectra of ACFS are studied.The C13-NMR spectra of ACFs can be divided into six bands that are assigned to methyl and methylene groups,hydroxyl and ether groups.acetal (or methylenedioxy) carbon,graphite-like aromatic carbon structure,phenol,and quinone groups,respectively.Only phosphorous pentoxide exists on ACFs and CFs.Moreover,most of them are stuck over the crystal face but not at the edge of graphite-like micro-crystal.The carbonization and activation conditions affect the C13-NMR spectra of ACFs.The experimental rsults indicate that the redox reaction of ACFs with oxidants greatly consumes C-H group.

  8. Chemical state of mercury and selenium in sewage sludge ash based P-fertilizers.

    Science.gov (United States)

    Vogel, Christian; Krüger, Oliver; Herzel, Hannes; Amidani, Lucia; Adam, Christian

    2016-08-05

    Phosphorus-fertilizers from secondary resources such as sewage sludge ash (SSA) will become more important in the future as they could substitute conventional fertilizers based on the nonrenewable resource phosphate rock. Thermochemical approaches were developed which remove heavy metals from SSA prior to its fertilizer application on farmlands. We analyzed the chemical state of mercury and selenium in SSA before and after thermochemical treatment under different conditions for P-fertilizer production by X-ray absorption near edge structure (XANES) spectroscopy. In some incineration plants the mercury loaded carbon adsorber from off-gas cleaning was collected together with the SSA for waste disposal. SSAs from those plants contained mercury mainly bound to carbon/organic material. The other SSAs contained inorganic mercury compounds which are most probably stabilized in the SSA matrix and were thus not evaporated during incineration. During thermochemical treatment, carbon-bound mercury was removed quantitatively. In contrast, a certain immobile fraction of inorganic mercury compounds remained in thermochemically treated SSA, which were not clearly identified. HgSe might be one of the inorganic compounds, which is supported by results of Se K-edge XANES spectroscopy. Furthermore, the chemical state of selenium in the SSAs was very sensitive to the conditions of the thermochemical treatment.

  9. Chemically robust platform for optical solid-state conducting polymer sensor

    Science.gov (United States)

    Holt, A. L.; Bearinger, J. P.; Carter, S. A.

    2006-10-01

    Conjugated polymers are unique materials for use in the development of chemical and biological sensors because of their widely tunable optical and electrical properties that allow them dual functionality as both the sensing element and the signal transducer. Furthermore, as optical photoluminescence based sensors, electroactive polymers are found to exhibit high sensitivity due to the ability of the analyte of interest to quench the photoluminescence of the entire polymer chain. In order to produce a more chemically robust thin film for use as a "solid-state" optical sensor, we succeeded in grafting various poly (3-alkyl-thiophene)s to optically transparent substrates such as glass, quartz, and ITO coated glass. This was accomplished by first grafting a thiophene monomer to the surface then chemically growing the films via oxidative polymerization. XPS studies indicated that each chemical step was accurately understood. The polythiophene growth, unaltered by sonication and tape peeling tests, was uniform across the substrate and could be directed by selective silanization of the substrate. Film thicknesses range from 20 to 200 nm and exhibit varying degrees of surface roughness, depending on the polymerization process. The reaction times and solvents were varied in order to optimize the desired film properties. The absorption and photoluminescence properties of the thin films compared well with literature on spun-cast polythiophene films, as did the electrical conductivities of the doped and undoped material. The photoluminescence intensities of the films are found to be unaffected by paraquat in water but are sensitive to trace amounts of ferric chloride in acetonitrile with measurable Stern Volmer constants.

  10. STEM: Science Technology Engineering Mathematics. State-Level Analysis

    Science.gov (United States)

    Carnevale, Anthony P.; Smith, Nicole; Melton, Michelle

    2011-01-01

    The science, technology, engineering, and mathematics (STEM) state-level analysis provides policymakers, educators, state government officials, and others with details on the projections of STEM jobs through 2018. This report delivers a state-by-state snapshot of the demand for STEM jobs, including: (1) The number of forecast net new and…

  11. Wellbore stability analysis in chemically active shale formations

    Directory of Open Access Journals (Sweden)

    Shi Xiang-Chao

    2016-01-01

    Full Text Available Maintaining wellbore stability involves significant challenges when drilling in low-permeability reactive shale formations. In the present study, a non-linear thermo-chemo-poroelastic model is provided to investigate the effect of chemical, thermal, and hydraulic gradients on pore pressure and stress distributions near the wellbores. The analysis indicates that when the solute concentration of the drilling mud is higher than that of the formation fluid, the pore pressure and the effective radial and tangential stresses decrease, and v. v. Cooling of the lower salinity formation decreases the pore pressure, radial and tangential stresses. Hole enlargement is the combined effect of shear and tensile failure when drilling in high-temperature shale formations. The shear and tensile damage indexes reveal that hole enlargement occurs in the vicinity of the wellbore at an early stage of drilling. This study also demonstrates that shale wellbore stability exhibits a time-delay effect due to changes in the pore pressure and stress. The delay time computed with consideration of the strength degradation is far less than that without strength degradation.

  12. A spectroscopic analysis of the chemically peculiar star HD207561

    CERN Document Server

    Joshi, S; Martinez, P; Sachkov, M; Joshi, Y C; Seetha, S; Chakradhari, N K; Mary, D L; Girish, V; Ashoka, B N

    2012-01-01

    In this paper we present a high-resolution spectroscopic analysis of the chemically peculiar star HD207561. During a survey programme to search for new roAp stars in the Northern hemisphere, Joshi et al. (2006) observed significant photometric variability on two consecutive nights in the year 2000. The amplitude spectra of the light curves obtained on these two nights showed oscillations with a frequency of 2.79 mHz [P~6-min]. However, subsequent follow-up observations could not confirm any rapid variability. In order to determine the spectroscopic nature of HD207561, high-resolution spectroscopic and spectro-polarimetric observations were carried out. A reasonable fit of the calculated Hbeta line profile to the observed one yields the effective temperature (Teff) and surface gravity (log g) as 7300 K and 3.7 dex, respectively. The derived projected rotational velocity (vsin i) for HD207561 is 74 km/sec indicative of a relatively fast rotator. The position of HD207561 in the H-R diagram implies that this is s...

  13. Nonradiological chemical pathway analysis and identification of chemicals of concern for environmental monitoring at the Hanford Site

    Energy Technology Data Exchange (ETDEWEB)

    Blanton, M.L.; Cooper, A.T.; Castleton, K.J.

    1995-11-01

    Pacific Northwest`s Surface Environmental Surveillance Project (SESP) is an ongoing effort tot design, review, and conducted monitoring on and off the Hanford site. Chemicals of concern that were selected are listed. Using modeled exposure pathways, the offsite cancer incidence and hazard quotient were calculated and a retrospective pathway analysis performed to estimate what onsite concentrations would be required in the soil for each chemical of concern and other detected chemicals that would be required to obtain an estimated offsite human-health risk of 1.0E-06 cancer incidence or 1.0 hazard quotient. This analysis indicates that current nonradiological chemical contamination occurring on the site does not pose a significant offsite human-health risk; the highest cancer incidence to the offsite maximally exposed individual was from arsenic (1.76E-10); the highest hazard quotient was chromium(VI) (1.48E-04). The most sensitive pathways of exposure were surfacewater and aquatic food consumption. Combined total offsite excess cancer incidence was 2.09E-10 and estimated hazard quotient was 2.40E-04. Of the 17 identified chemicals of concern, the SESP does not currently (routinely) monitor arsenic, benzo(a)pyrene, bis(2- ethylhexyl)phthalate (BEHP), and chrysene. Only 3 of the chemicals of concern (arsenic, BEHP, chloroform) could actually occur in onsite soil at concern high enough to cause a 1.0E-06 excess cancer incidence or a 1.0 hazard index for a given offsite exposure pathway. During the retrospective analysis, 20 other chemicals were also evaluated; only vinyl chloride and thallium could reach targeted offsite risk values.

  14. Transmission coefficients for chemical reactions with multiple states: role of quantum decoherence.

    Science.gov (United States)

    de la Lande, Aurélien; Řezáč, Jan; Lévy, Bernard; Sanders, Barry C; Salahub, Dennis R

    2011-03-23

    Transition-state theory (TST) is a widely accepted paradigm for rationalizing the kinetics of chemical reactions involving one potential energy surface (PES). Multiple PES reaction rate constants can also be estimated within semiclassical approaches provided the hopping probability between the quantum states is taken into account when determining the transmission coefficient. In the Marcus theory of electron transfer, this hopping probability was historically calculated with models such as Landau-Zener theory. Although the hopping probability is intimately related to the question of the transition from the fully quantum to the semiclassical description, this issue is not adequately handled in physicochemical models commonly in use. In particular, quantum nuclear effects such as decoherence or dephasing are not present in the rate constant expressions. Retaining the convenient semiclassical picture, we include these effects through the introduction of a phenomenological quantum decoherence function. A simple modification to the usual TST rate constant expression is proposed: in addition to the electronic coupling, a characteristic decoherence time τ(dec) now also appears as a key parameter of the rate constant. This new parameter captures the idea that molecular systems, although intrinsically obeying quantum mechanical laws, behave semiclassically after a finite but nonzero amount of time (τ(dec)). This new degree of freedom allows a fresh look at the underlying physics of chemical reactions involving more than one quantum state. The ability of the proposed formula to describe the main physical lines of the phenomenon is confirmed by comparison with results obtained from density functional theory molecular dynamics simulations for a triplet to singlet transition within a copper dioxygen adduct relevant to the question of dioxygen activation by copper monooxygenases.

  15. Thermodynamic analysis of alternate energy carriers, hydrogen and chemical heat pipes

    Science.gov (United States)

    Cox, K. E.; Carty, R. H.; Conger, W. L.; Soliman, M. A.; Funk, J. E.

    1976-01-01

    Hydrogen and chemical heat pipes were proposed as methods of transporting energy from a primary energy source (nuclear, solar) to the user. In the chemical heat pipe system, primary energy is transformed into the energy of a reversible chemical reaction; the chemical species are then transmitted or stored until the energy is required. Analysis of thermochemical hydrogen schemes and chemical heat pipe systems on a second law efficiency or available work basis show that hydrogen is superior especially if the end use of the chemical heat pipe is electrical power.

  16. Methods used to characterize the chemical composition and biological activity of environmental waters throughout the United States, 2012-14

    Science.gov (United States)

    Romanok, Kristin M.; Reilly, Timothy J.; Barber, Larry B.; Boone, J. Scott; Buxton, Herbert T.; Foreman, William T.; Furlong, Edward T.; Hladik, Michelle; Iwanowicz, Luke R.; Journey, Celeste; Kolpin, Dana W.; Kuivila, Kathryn; Loftin, Keith A.; Mills, Marc A.; Meyer, Michael T.; Orlando, James L.; Smalling, Kelly L.; Villeneuve, Daniel L.; Bradley, Paul M.

    2017-03-22

    A vast array of chemical compounds are in wide commercial use in the United States, and the potential ecological and human-health effect of exposure to chemical mixtures has been identified as a high priority in environment health science. Awareness of the potential effects of low-level chemical exposures is rising. The U.S. Geological Survey, in cooperation with the U.S. Environmental Protection Agency, conducted a study in which samples were collected from 38 streams in 25 States to provide an overview of contaminants found in stream water across the Nation. Additionally, biological screening assays were used to help determine any potential ecological and human-health effects of these chemical mixtures and to prioritize target chemicals for future toxicological studies. This report describes the site locations and the sampling and analytical methods and quality-assurance procedures used in the study.

  17. Chemical reactivity of graphene oxide towards amines elucidated by solid-state NMR

    Science.gov (United States)

    Vacchi, Isabella A.; Spinato, Cinzia; Raya, Jésus; Bianco, Alberto; Ménard-Moyon, Cécilia

    2016-07-01

    Graphene oxide (GO) is an attractive nanomaterial for many applications. Controlling the functionalization of GO is essential for the design of graphene-based conjugates with novel properties. But, the chemical composition of GO has not been fully elucidated yet. Due to the high reactivity of the oxygenated moieties, mainly epoxy, hydroxyl and carboxyl groups, several derivatization reactions may occur concomitantly. The reactivity of GO with amine derivatives has been exploited in the literature to design graphene-based conjugates, mainly through amidation. However, in this study we undoubtedly demonstrate using magic angle spinning (MAS) solid-state NMR that the reaction between GO and amine functions occurs via ring opening of the epoxides, and not by amidation. We also prove that there is a negligible amount of carboxylic acid groups in two GO samples obtained by a different synthesis process, hence eliminating the possibility of amidation reactions with amine derivatives. This work brings additional insights into the chemical reactivity of GO, which is fundamental to control its functionalization, and highlights the major role of MAS NMR spectroscopy for a comprehensive characterization of derivatized GO.Graphene oxide (GO) is an attractive nanomaterial for many applications. Controlling the functionalization of GO is essential for the design of graphene-based conjugates with novel properties. But, the chemical composition of GO has not been fully elucidated yet. Due to the high reactivity of the oxygenated moieties, mainly epoxy, hydroxyl and carboxyl groups, several derivatization reactions may occur concomitantly. The reactivity of GO with amine derivatives has been exploited in the literature to design graphene-based conjugates, mainly through amidation. However, in this study we undoubtedly demonstrate using magic angle spinning (MAS) solid-state NMR that the reaction between GO and amine functions occurs via ring opening of the epoxides, and not by

  18. Chemical imaging of ambient aerosol particles: Observational constraints on mixing state parameterization

    Science.gov (United States)

    O'Brien, Rachel E.; Wang, Bingbing; Laskin, Alexander; Riemer, Nicole; West, Matthew; Zhang, Qi; Sun, Yele; Yu, Xiao-Ying; Alpert, Peter; Knopf, Daniel A.; Gilles, Mary K.; Moffet, Ryan C.

    2015-09-01

    A new parameterization for quantifying the mixing state of aerosol populations has been applied for the first time to samples of ambient particles analyzed using spectro-microscopy techniques. Scanning transmission X-ray microscopy/near edge X-ray absorption fine structure (STXM/NEXAFS) and computer-controlled scanning electron microscopy/energy dispersive X-ray spectroscopy (CCSEM/EDX) were used to probe the composition of the organic and inorganic fraction of individual particles collected on 27 and 28 June during the 2010 Carbonaceous Aerosols and Radiative Effects study in the Central Valley, California. The first field site, T0, was located in downtown Sacramento, while T1 was located near the Sierra Nevada Mountains. Mass estimates of the aerosol particle components were used to calculate mixing state metrics, such as the particle-specific diversity, bulk population diversity, and mixing state index, for each sample. The STXM data showed evidence of changes in the mixing state associated with a buildup of organic matter confirmed by collocated measurements, and the largest impact on the mixing state was due to an increase in soot dominant particles during this buildup. The mixing state from STXM was similar between T0 and T1, indicating that the increased organic fraction at T1 had a small effect on the mixing state of the population. The CCSEM/EDX analysis showed the presence of two types of particle populations: the first was dominated by aged sea-salt particles and had a higher mixing state index (indicating a more homogeneous population); the second was dominated by carbonaceous particles and had a lower mixing state index.

  19. Hyperentanglement-assisted Bell-state analysis

    CERN Document Server

    Walborn, S P; Monken, C H

    2003-01-01

    We propose a simple scheme for complete Bell-state measurement of photons using hyperentangled states - entangled in multiple degrees of freedom. In addition to hyperentanglement, our scheme requires only linear optics and single photon detectors, and is realizable with current technology. At the cost of additional classical communication, our Bell-state measurement can be implemented non-locally. We discuss the possible application of these results to quantum dense coding and quantum teleportation.

  20. Recurrence quantification analysis of chimera states

    Science.gov (United States)

    Santos, M. S.; Szezech, J. D.; Batista, A. M.; Caldas, I. L.; Viana, R. L.; Lopes, S. R.

    2015-10-01

    Chimera states, characterised by coexistence of coherence and incoherence in coupled dynamical systems, have been found in various physical systems, such as mechanical oscillator networks and Josephson-junction arrays. We used recurrence plots to provide graphical representations of recurrent patterns and identify chimera states. Moreover, we show that recurrence plots can be used as a diagnostic of chimera states and also to identify the chimera collapse.

  1. Matching Element Symbols with State Abbreviations: A Fun Activity for Browsing the Periodic Table of Chemical Elements

    Science.gov (United States)

    Woelk, Klaus

    2009-01-01

    A classroom activity is presented in which students are challenged to find matches between the United States two-letter postal abbreviations for states and chemical element symbols. The activity aims to lessen negative apprehensions students might have when the periodic table of the elements with its more than 100 combinations of letters is first…

  2. Some Physico-Chemical and Bacteriological Characteristics of Soil Samples around Calabar Metropolis, Cross River State, Nigeria

    Directory of Open Access Journals (Sweden)

    Okorafor, K. A

    2016-08-01

    Full Text Available Physico-chemical and bacteriological parameters of soil samples around Calabar Metropolis, Cross River State, Nigeria were examined to determine the pollution status of the soil quality. Results of the physico-chemical analysis showed that the soil samples had pH range of 4.4 – 5.2. Tinapa soil has the highest value of Copper (39.63mg/kg and Nickel (11.36mg/kg and Anantigha has the highest value of Zinc (14.59mg/kg, Iron Fe (78.19mg/kg and Manganese (47.42mg/kg. The results revealed a high total count of 23.5x106 cfu/g in Anantigha and 24.5x10-3 cfu/g in Tinapa for bacteria and fungi respectively. Some bacteria isolates found during the study includes, Escherichia coli, Bacillus subtilus, Clostridium sp, Arthrobacter sp, Streptomyces sp, Nocardia sp, Pseudomonas sp and Micrococcus sp., and Fungal isolates includes, Actinomycete sp, Verticullium sp, Aspergillus sp, Mucor sp, Nigospora sp and Paecilomyces sp. From the result, soil sample from Anantigha have comparatively the highest Total Bacterial Counts compared to the other two locations. The health implications of this work is that Anantigha and Tinapa areas being low lying were likely, because of the presence of Escherichia coli, to experience gastro-intestinal diseases such as dysentery and cholera than the Ediba environments.

  3. Research on the chemical adsorption precursor state of CaCl2-NH3 for adsorption refrigeration

    Institute of Scientific and Technical Information of China (English)

    WANG; Liwei; WANG; Ruzhu; WU; Jingyi; WANG; Kai

    2005-01-01

    As a type of chemical adsorption working pair, the physical adsorption occurs first for CaCl2-NH3 because the effective reaction distance for van der Waals force is longer than that for chemical reaction force, and this physical adsorption state is named the precursor state of chemical adsorption. In order to get the different precursor states of CaCl2-NH3, the different distances between NH3 gas and Ca2+ are realized by the control of different phenomena of swelling and agglomeration in the process of adsorption. When the serious swelling exists while the agglomeration does not exist in the process of adsorption, experimental results show that the activated energy consumed by adsorption reaction increases for the reason of longer distance between Ca2+ and NH3, and at the same time the performance attenuation occurs in the repeated adsorption cycles. When the agglomeration occurs in the process of adsorption, the activated energy for the transition from precursor state to chemical adsorption decreases because the distance between NH3 gas and Ca2+ is shortened by the limited expansion space of adsorbent, and at the same time the performance attenuation does not occur. The adsorption refrigeration isobars are researched by the precursor state of chemical adsorption; results also show that the precursor state is a key factor for isobaric adsorption performance while the distribution of Ca2+ does not influence the permeation of NH3 gas in adsorbent.

  4. Chemical Imaging of Ambient Aerosol Particles: Observational Constraints on Mixing State Parameterization

    Energy Technology Data Exchange (ETDEWEB)

    O' Brien, Rachel; Wang, Bingbing; Laskin, Alexander; Riemer, Nicole; West, Matthew; Zhang, Qi; Sun, Yele; Yu, Xiao-Ying; Alpert, Peter A.; Knopf, Daniel A.; Gilles, Mary K.; Moffet, Ryan

    2015-09-28

    A new parameterization for quantifying the mixing state of aerosol populations has been applied for the first time to samples of ambient particles analyzed using spectro-microscopy techniques. Scanning transmission x-ray microscopy/near edge x-ray absorption fine structure (STXM/NEXAFS) and computer controlled scanning electron microscopy/energy dispersive x-ray spectroscopy (CCSEM/EDX) were used to probe the composition of the organic and inorganic fraction of individual particles collected on June 27th and 28th during the 2010 Carbonaceous Aerosols and Radiative Effects (CARES) study in the Central Valley, California. The first field site, T0, was located in downtown Sacramento, while T1 was located near the Sierra Nevada Mountains. Mass estimates of the aerosol particle components were used to calculate mixing state metrics, such as the particle-specific diversity, bulk population diversity, and mixing state index, for each sample. Both microscopy imaging techniques showed more changes over these two days in the mixing state at the T0 site than at the T1 site. The STXM data showed evidence of changes in the mixing state associated with a build-up of organic matter confirmed by collocated measurements and the largest impact on the mixing state was due to an increase in soot dominant particles during this build-up. The CCSEM/EDX analysis showed the presence of two types of particle populations; the first was dominated by aged sea salt particles and had a higher mixing state index (indicating a more homogeneous population), the second was dominated by carbonaceous particles and had a lower mixing state index.

  5. Chemical fingerprinting of whitewares from Nanwa site of the Chinese Erlitou state

    Energy Technology Data Exchange (ETDEWEB)

    Li Baoping [Centre for Microscopy and Microanalysis, University of Queensland, QLD 4072 (Australia)], E-mail: b.li@uq.edu.au; Liu Li [Archaeology Program, La Trobe University, Melbourne, VIC 3086 (Australia); Zhao Jianxin [Centre for Microscopy and Microanalysis, University of Queensland, QLD 4072 (Australia); Chen Xingcan [Institute of Archaeology, Chinese Academy of Social Sciences, Beijing 100710 (China); Feng Yuexing [Centre for Microscopy and Microanalysis, University of Queensland, QLD 4072 (Australia); Han Guohe; Zhu Junxiao [Department of Archaeology, Zhengzhou University, Zhengzhou 450052 (China)

    2008-06-15

    Whitewares are among the most significant finds from Erlitou, China's earliest state (c. 1900-1500 BC). They were primarily discovered in small numbers from elite tombs of a few sites, leading to the hypothesis that they were made at only a few places and then circulated as prestige items. Recent archaeological work indicates Nanwa may be a whiteware production site. To facilitate determining provenances, we compare the ICP-MS trace elements and TIMS Sr isotopes of Nanwa whitewares with those from Tang dynasty (618-907 AD) Gongxian kilns and Song dynasty (960-1279 AD) Ding kilns. Although all were made of white-firing kaolinic clays, each of the three groups shows a different chemical composition. Furthermore, samples from Nanwa are chemically consistent and restricted in a way analogous to those from Gongxian and Ding, implying that Nanwa whiteware was probably produced in situ. In addition, Gongxian and Ding samples define two separate linear arrays in their {sup 87}Rb/{sup 86}Sr versus {sup 87}Sr/{sup 86}Sr ratios, demonstrating that the clays for these samples are respectively related geochemically. Nanwa samples fall out of the linear arrays of both Gongxian and Ding, indicating that Nanwa whiteware clays were not derived from the same source rock as Gongxian clays, although the two sites are only some 25.5 km apart. In sum, beyond the general similarity of kaolinic clays used at Nanwa, Gongxian and Ding and the geographical proximity of those sites, finer distinctions of elemental and Sr isotopic contents indicate relatively unique chemical characteristics for each group. These traits provide valuable criteria to source traded ceramics of uncertain origins.

  6. Effects of temperature and relative humidity on the solid-state chemical stability of ranitidine hydrochloride.

    Science.gov (United States)

    Teraoka, R; Otsuka, M; Matsuda, Y

    1993-06-01

    The chemical stability of ranitidine HCl in solution and in the solid state at various temperatures was investigated by high-performance liquid chromatography. Ranitidine HCl was unstable in lower pH buffer solutions, and the percent degradation after 72 h increased as the pH of the buffer solution was reduced. The percent degradation in the unbuffered solution increased dose dependently. The critical relative humidity (CRH) of the ranitidine HCl bulk powder was approximately 67% relative humidity (RH). The amount of water adsorbed onto the sample above the CRH was proportional to the RH level. The percent degradation of the powder below 50% RH was almost negligible because, at this level, it was a solid. The percent degradation at 60-70% RH was higher than that above 70% RH. Ranitidine HCl powder was unstable around the CRH.

  7. Meta-Analysis of the Chemical and Non-Chemical Stressors Affecting Childhood Obesity?

    Science.gov (United States)

    Background: Worldwide, approximately 42 million children under the age of 5 years are considered overweight or obese. While much research has focused on individual behaviors impacting obesity, little research has emphasized the complex interactions of numerous chemical and non-ch...

  8. Interface chemical states of NiO/NiFe films and their effects on magnetic properties

    Institute of Scientific and Technical Information of China (English)

    于广华; 柴春林; 朱逢吾; 赖武彦

    2002-01-01

    Ta/NiOx/Ni81Fe19/Ta multilayers were prepared by rf reactive and dc magnetron sputtering.The exchange coupling field (Hex) and the coercivity (Hc) of NiOx/Ni81Fe19 as a function of the ratio of Ar to O2 during the deposition process were studied.The composition and chemical states at the interface region of NiOx/NiFe were also investigated using the X-ray photoelectron spectroscopy (XPS) and peak decomposition technique.The results show that the ratio of Ar to O2 has great effect on the nickel chemical states in NiOx film.When the ratio of Ar to O2 is equal to 7 and the argon sputtering pressure is 0.57 Pa,the x value is approximately 1 and the valence of nickel is +2.At this point,NiOx is antiferromagnetic NiO and the corresponding Hex is the largest.As the ratio of Ar/O2 deviates from 7,the exchange coupling field (Hex) will decrease due to the presence of magnetic impurities such as Ni+3 or metallic Ni at the interface region of NiOx/NiFe,while the coercivity (Hc) will increase due to the metallic Ni.XPS studies also show that there are two thermodynamically favorable reactions at the NiO/NiFe interface: NiO+Fe=Ni+FeO and 3NiO+2Fe=3Ni+Fe2O3.These interface reaction products are magnetic impurities at the interface region of NiO/NiFe.It is believed that these magnetic impurities would have effect on the exchange coupling field (Hex) and the coercivity (Hc) of NiO/NiFe.

  9. Network structural analysis using directed graph for chemical reaction analysis in weakly-ionized plasmas

    Science.gov (United States)

    Nobuto, Kyosuke; Mizui, Yasutaka; Miyagi, Shigeyuki; Sakai, Osamu; Murakami, Tomoyuki

    2016-09-01

    We visualize complicated chemical reaction systems in weakly-ionized plasmas by analysing network structure for chemical processes, and calculate some indexes by assuming interspecies relationships to be a network to clarify them. With the current social evolution, the mean size of general data which we can use in computers grows huge, and significance of the data analysis increases. The methods of the network analysis which we focus on in this study do not depend on a specific analysis target, but the field where it has been already applied is still limited. In this study, we analyse chemical reaction systems in plasmas for configuring the network structure. We visualize them by expressing a reaction system in a specific plasma by a directed graph and examine the indexes and the relations with the characteristic of the species in the reaction system. For example, in the methane plasma network, the centrality index reveals importance of CH3 in an influential position of species in the reaction. In addition, silane and atmospheric pressure plasmas can be also visualized in reaction networks, suggesting other characteristics in the centrality indexes.

  10. Integrated label-free silicon nanowire sensor arrays for (bio)chemical analysis

    NARCIS (Netherlands)

    De, Arpita; Nieuwkasteele, van Jan; Carlen, Edwin T.; Berg, van den Albert

    2013-01-01

    We present a label-free (bio)chemical analysis platform that uses all-electrical silicon nanowire sensor arrays integrated with a small volume microfluidic flow-cell for real-time (bio)chemical analysis and detection. The integrated sensing platform contains an automated multi-sample injection syste

  11. SOIL QUALITY ASSESSMENT BASED ON CHEMICAL, ENZYMATIC AND BACTERIOLOGICAL ANALYSIS

    Directory of Open Access Journals (Sweden)

    Sofia-Paulina BALAURE

    2012-01-01

    Full Text Available This study highlights the problem of soil pollution as the result of human activities. Soil pollutans may be either chemicals or biological in nature. microbial enzymatic activities are often proposed as indicators of environmental stress. The soil samples were submitted by chemical, microbiological and enzymatic analyses. Chemical analyses were been made for determinating the heavy metals. Heavy metals from the forest soil were represented by Cu, Zn, Mn, Ni, Pb, Cd and Cr. To evaluate the concentration in heavy metals from the filtrate, we used a acetylene-nitrous oxide flame atomic absorption spectrophotometry. Potential dehydrogenase activity, the only indicator of the possible sources of pollution, excluded the presence of either chemical or biological pollution. The number of bacteria involved in the biogeochemical cycle of nitrogen in the analyzed soil indicated a high efficiency regarding the mineralization of the organic residues of plant and animal origin.

  12. China Rubber Chemicals Production and Market Situation Analysis

    Institute of Scientific and Technical Information of China (English)

    Liang Cheng

    2011-01-01

    Because the stimulus driven impact of the rapid growth of tire and other rubber products' output,in recent years,the production and marketing of domestic rubber chemicals appear to increase,and the specific production and marketing conditions are as follows: 1.Rapid Growth of Chemicals Output From 2009 to 2010,in China an upsurge of expanding or building new rubber chemicals equipment was raised.These equipment were planned to be put into production in 2010 with newly increased production capacity of about 120,000 tons,among which there were 40,000 tons antioxidant 4020,50,000tons accelerator M,and about 40,000 tons other Chemicals.In 2010,the total output was 701,000 tons,with year-on-year growth of 17.8% or so.In 2010,the total sales volume of domestic rubber chemicals were 13 billion yuan,and the export volume was about 180,000 tons,basically the same with that in 2009.See the statistics of domestic rubber chemicals output from 2009 to 2010 in Table 1.

  13. Ultrastructural Analysis of Urinary Stones by Microfocus Computed Tomography and Comparison with Chemical Analysis

    Directory of Open Access Journals (Sweden)

    Tolga Karakan

    2016-06-01

    Full Text Available Objective: To investigate the ultra-structure of urinary system stones using micro-focus computed tomography (MCT, which makes non-destructive analysis and to compare with wet chemical analysis. Methods: This study was carried out at the Ankara Train­ing and Research hospital. Renal stones, removed from 30 patients during percutaneous nephrolithotomy (PNL surgery, were included in the study. The stones were blindly evaluated by the specialists with MCT and chemi­cal analysis. Results: The comparison of the stone components be­tween chemical analysis and MCT, showed that the rate of consistence was very low (p0.05. It was also seen that there was no significant relation between its 3D structure being heterogeneous or homogenous. Conclusion: The stone analysis with MCT is a time con­suming and costly method. This method is useful to un­derstand the mechanisms of stone formation and an im­portant guide to develop the future treatment modalities.

  14. Refractometry and interferometry in chemical analysis; Refractometrie et interferometrie en analyse chimique

    Energy Technology Data Exchange (ETDEWEB)

    Veret, C. [Faculte des Sciences de Paris, 75 (France)

    2000-03-01

    In vacuum, an electromagnetic radiation is propagated at a constant velocity. But, when it has to pass through a physical medium, it is submitted to different interactions (for instance: absorption, diffusion, refraction, polarization, dispersion, fluorescence) which lead to a modification of its propagation. In the frequency ranges of the radiation for which the absorption is not very important, the modifications of the propagation velocity of a radiation can bring data on the nature and/or the physical conditions (pressure, temperature) of a medium, whatever its state be: gas, liquid or solid. Thus, the absolute refractive index of a medium in relation to vacuum is defined as the ratio c/v of the propagation velocity c of a monochromatic electromagnetic radiation in vacuum at its velocity v in this medium. The photonic refractometry (field of ultraviolet, visible and infrared radiations) is the set of the measure techniques of the refractive indexes having a role in chemical analysis. The refractometry measures can only be applied to media which are optically transparent. After having described these techniques, the author presents their uses in chemical analysis. (O.M.)

  15. X-ray texture analysis of paper coating pigments and the correlation with chemical composition analysis

    Science.gov (United States)

    Roine, J.; Tenho, M.; Murtomaa, M.; Lehto, V.-P.; Kansanaho, R.

    2007-10-01

    The present research experiments the applicability of x-ray texture analysis in investigating the properties of paper coatings. The preferred orientations of kaolin, talc, ground calcium carbonate, and precipitated calcium carbonate particles used in four different paper coatings were determined qualitatively based on the measured crystal orientation data. The extent of the orientation, namely, the degree of the texture of each pigment, was characterized quantitatively using a single parameter. As a result, the effect of paper calendering is clearly seen as an increase on the degree of texture of the coating pigments. The effect of calendering on the preferred orientation of kaolin was also evident in an independent energy dispersive spectrometer analysis on micrometer scale and an electron spectroscopy for chemical analysis on nanometer scale. Thus, the present work proves x-ray texture analysis to be a potential research tool for characterizing the properties of paper coating layers.

  16. An introduction to state space time series analysis.

    NARCIS (Netherlands)

    Commandeur, J.J.F. & Koopman, S.J.

    2007-01-01

    Providing a practical introduction to state space methods as applied to unobserved components time series models, also known as structural time series models, this book introduces time series analysis using state space methodology to readers who are neither familiar with time series analysis, nor wi

  17. International Research Project on the Effects of Chemical Ageing of Polymers on Performance Properties: Chemical and Thermal Analysis

    Science.gov (United States)

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

    1996-01-01

    Work during the past six months has included significant research in several areas aimed at further clarification of the aging and chemical failure mechanism of thermoplastics (PVDF or Tefzel) pipes. Among the areas investigated were the crystallinity changes associated with both the Coflon and Tefzel after various simulated environmental exposures using X-ray diffraction analysis. We have found that significant changes in polymer crystallinity levels occur as a function of the exposures. These crystallinity changes may have important consequences on the fracture, fatigue, tensile, and chemical resistance of the materials. We have also noted small changes in the molecular weight distribution. Again these changes may result in variations in the mechanical and chemical properties in the material. We conducted numerous analytical studies with methods including X-ray Diffraction, Gel Permeation Chromatography, Fourier Transform Infrared Spectroscopy, Ultra- Violet Scanning Analysis, GC/Mass Spectrometry, Differential Scanning Calorimetry and Thermomechanical Analysis. In the ultra-violet analysis we noted the presence of an absorption band indicative of triene formation. We investigated a number of aged samples of both Tefzel and Coflon that were forwarded from MERL. We also cast films at SWT and subjected these films to a refluxing methanol 1% ethylene diamine solution. An updated literature search was conducted using Dialog and DROLLS to identify any new papers that may have been published in the open literature since the start of this project. The updated literature search and abstracts are contained in the Appendix section of this report.

  18. An introduction to state space time series analysis.

    OpenAIRE

    Commandeur, J.J.F. & Koopman, S.J.

    2007-01-01

    Providing a practical introduction to state space methods as applied to unobserved components time series models, also known as structural time series models, this book introduces time series analysis using state space methodology to readers who are neither familiar with time series analysis, nor with state space methods. The only background required in order to understand the material presented in the book is a basic knowledge of classical linear regression models, of which a brief review is...

  19. Acoustic Imaging of Microstructure and Evaluation of the Adhesive's Physical, Mechanical and Chemical Properties Changes at Different Cure States

    Science.gov (United States)

    Severina, I. A.; Fabre, A. J.; Maeva, E. Yu.

    Epoxy thermoset adhesives transform during cure from liquid state into the highly cross-linked solid. Cure state of the material depends on condition of the reaction (temperature, pressure, time etc.) and resin/hardener ratio. It is known that the cure degree of the adhesive correlates with adhesion strength, which is critical for structural adhesives used in automotive, aerospace and marine industries. In this work, characterization of cure process of the adhesive with acoustic methods is presented. Evolution of the acoustic and elastic properties (attenuation, sound velocity, density, elastic moduli) during cure reaction was monitored in relation to the substantial physical and chemical changes of the material. These macro parameters of the adhesive were compared with the material's microstructure obtained by high-resolution acoustic microscopy technique in frequencies range of 50-400 MHz. Development of the microstructure of the adhesive as it cures at different conditions has been investigated. Appearance and development of the granular structure on the adhesive interface during cure reaction has been demonstrated. Acoustic images were analyzed by mathematical method to quantitatively characterize distribution of the adhesive's components. Statistical analysis of such images provides an accurate quantitative measure of the degree of cure of such samples. Research results presented in this paper can be useful as a basis for non-destructive evaluation of the adhesive materials

  20. Analysis of forward and inverse problems in chemical dynamics and spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Rabitz, H. [Princeton Univ., NJ (United States)

    1993-12-01

    The overall scope of this research concerns the development and application of forward and inverse analysis tools for problems in chemical dynamics and chemical kinetics. The chemical dynamics work is specifically associated with relating features in potential surfaces and resultant dynamical behavior. The analogous inverse research aims to provide stable algorithms for extracting potential surfaces from laboratory data. In the case of chemical kinetics, the focus is on the development of systematic means to reduce the complexity of chemical kinetic models. Recent progress in these directions is summarized below.

  1. Modular verification of chemical reaction network encodings via serializability analysis.

    Science.gov (United States)

    Lakin, Matthew R; Stefanovic, Darko; Phillips, Andrew

    2016-06-13

    Chemical reaction networks are a powerful means of specifying the intended behaviour of synthetic biochemical systems. A high-level formal specification, expressed as a chemical reaction network, may be compiled into a lower-level encoding, which can be directly implemented in wet chemistry and may itself be expressed as a chemical reaction network. Here we present conditions under which a lower-level encoding correctly emulates the sequential dynamics of a high-level chemical reaction network. We require that encodings are transactional, such that their execution is divided by a "commit reaction" that irreversibly separates the reactant-consuming phase of the encoding from the product-generating phase. We also impose restrictions on the sharing of species between reaction encodings, based on a notion of "extra tolerance", which defines species that may be shared between encodings without enabling unwanted reactions. Our notion of correctness is serializability of interleaved reaction encodings, and if all reaction encodings satisfy our correctness properties then we can infer that the global dynamics of the system are correct. This allows us to infer correctness of any system constructed using verified encodings. As an example, we show how this approach may be used to verify two- and four-domain DNA strand displacement encodings of chemical reaction networks, and we generalize our result to the limit where the populations of helper species are unlimited.

  2. Evaluating Chemical Persistence in a Multimedia Environment: ACART Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Bennett, D.H.; McKone, T.E.; Kastenberg, W.E.

    1999-02-01

    For the thousands of chemicals continuously released into the environment, it is desirable to make prospective assessments of those likely to be persistent. Persistent chemicals are difficult to remove if adverse health or ecological effects are later discovered. A tiered approach using a classification scheme and a multimedia model for determining persistence is presented. Using specific criteria for persistence, a classification tree is developed to classify a chemical as ''persistent'' or ''non-persistent'' based on the chemical properties. In this approach, the classification is derived from the results of a standardized unit world multimedia model. Thus, the classifications are more robust for multimedia pollutants than classifications using a single medium half-life. The method can be readily implemented and provides insight without requiring extensive and often unavailable data. This method can be used to classify chemicals when only a few properties are known and be used to direct further data collection. Case studies are presented to demonstrate the advantages of the approach.

  3. Load Characteristics Analysis of State Grid

    Institute of Scientific and Technical Information of China (English)

    Chen Wei; Zhou Feng; Han Xinyang; Shan Baoguo; Zhu Li

    2009-01-01

    @@ Introduction Analysis and forecast of load characteristics are important aspects in power market analysis and prediction.Correctly mastering grid load characteristics and its development trend is not only the vital basis for power planning,generation and operation,but also the important references for formulating the relevant policies.It is usually very hard to grasp the load characteristics of power grid.

  4. Analysis of a reheat gas turbine cycle with chemical recuperation using Aspen

    Energy Technology Data Exchange (ETDEWEB)

    Harvey, S.; Kane, N`Diaye [ISITEM - Lab. d`Energetique, Nantes (France)

    1996-11-01

    Present-day high performance gas turbine based cycles use the combined cycle concept in which the heat in the hot turbine exhaust stream is used to raise steam which can be used to generate electricity using a steam turbine. Recent attention has focused in particular on the chemical heat recovery concept.The potential benefits of such cycles include high conversion efficiency, ultra-low NO{sub x} emission levels (less than 1 ppm) and high power density per unit of land. The low thermal NO{sub X} emissions result from the presence of hydrogen in the reformed fuel gas, which enables combustion at lower flame temperatures. Thus, a CRGT (Chemically Recuperated Gas Turbine) cycle can meet the strictest NO{sub x} limits in operation today without the need for selective catalytic reduction. Such environmental characteristics are the primary reason fuelling current interest in CRGT cycles. For design reasons, reheat combustors cannot be easily adapted to stationary gas turbines, and until recently the CRGT cycle seemed to be limited to aeroderivative gas turbine applications. However, ABB recently unveiled its new GT26 series stationary gas turbines using staged expansion with reheat combustion, allowing high thermal efficiencies with relatively low turbine inlet temperatures. This type of turbine appears particularly well-suited for chemical heat recovery. In this paper, we present a CRGT cycle based on a reheat gas turbine with key design features similar to those of ABB`s GT26 machine. The cycle analysis is performed using ASPEN+ process simulation software. The report includes a detailed first and second law analysis of the cycle. The results confirm that the energy conversion efficiencies of CRGT cycles cannot rival with the efficiencies achieved by state-of-the-art combined cycles. 12 refs, 3 figs, 5 tabs

  5. Fast Differential Analysis of Propolis Using Surface Desorption Atmospheric Pressure Chemical Ionization Mass Spectrometry

    Science.gov (United States)

    Huang, Xue-yong; Guo, Xia-li; Luo, Huo-lin; Fang, Xiao-wei; Zhu, Teng-gao; Zhang, Xing-lei; Chen, Huan-wen; Luo, Li-ping

    2015-01-01

    Mass spectral fingerprints of 24 raw propolis samples, including 23 from China and one from the United States, were directly obtained using surface desorption atmospheric pressure chemical ionization mass spectrometry (SDAPCI-MS) without sample pretreatment. Under the optimized experimental conditions, the most abundant signals were detected in the mass ranges of 70 to 500 m/z and 200 to 350 m/z, respectively. Principal component analyses (PCA) for the two mass ranges showed similarities in that the colors had a significant correlation with the first two PCs; in contrast there was no correlation with the climatic zones from which the samples originated. Analytes such as chrysin, pinocembrin, and quercetin were detected and identified using multiple stage mass spectrometry within 3 min. Therefore, SDAPCI-MS can be used for rapid and reliable high-throughput analysis of propolis. PMID:26339245

  6. ANALYSIS OF SOLUBLE CHEMICAL TRANSFER BY RUNOFF WATER IN FIELD

    Institute of Scientific and Technical Information of China (English)

    TONG Ju-xiu; YANG Jin-zhong

    2008-01-01

    In order to determine the main factors influencing soluble chemical transfer and corresponding techniques for reducing fertilizer loss caused by runoff in irrigated fields, a physically based two-layer model was developed with incomplete mixing theory. Different forms of incomplete mixing parameters were introduced in the model, which was successfully verified with previous published experimental data. According to comparison, the chemicals loss of fertilizer is very sensitive to the runoff-related parameter while it is not sensitive to the infiltration-related parameter. The calculated results show that the chemicals in infiltration water play an important role in the early time of rainfall even with saturated soil, and it is mainly in the runoff flow in the late rainfall. Therefore, prevention of shallow subsurface drainage in the early rainfall is an effective way to reduce fertilizer loss, and the coverage on soil surface is another effective way.

  7. Powerful chemical technique. [CSIR uses new x-ray diffractometer for structural chemical analysis

    Energy Technology Data Exchange (ETDEWEB)

    The CSIR's National Chemical Research Laboratory (NCRL) is now using one of the most powerful techniques available to determine the structure of molecules. It has recently acquired a Single Crystal X-ray Diffractometer. This powerful method provides the only means of determining the structure of certain compounds. NCRL scientists often carry out structure determinations to find out the relative or absolute stereochemistry of molecules. This is important when correlating physiological activity and structure, information which is necessary for synthesizing medicines with specific characteristics.

  8. Quantum physical states for describing photonic assisted chemical change: I. Torsional phenomenon at femtosecond time scale

    CERN Document Server

    Tapia, O

    2012-01-01

    Femtosecond torsional relaxation processes experimentally detected and recently reported by Clark et al. (Nature Phys. 8,225 (2012)) are theoretically dissected with a Hilbert/Fock quantum physical (QP) framework incorporating entanglement of photon/matter base states overcoming standard semi-classic vibrational descriptions. The quantum analysis of a generic Z/E (cis/trans) isomerization in abstract QP terms shed light to fundamental roles played by photonic spin and excited electronic singlet coupled to triplet states. It is shown that one photon activation cannot elicit femtosecond phenomenon, while a two-photon pulse would do. Estimated time scales for the two-photon case indicate the process to lie between a slower than electronic Franck-Condon-like transition yet faster than (semi-classic) vibration relaxation ones.

  9. Pathway Analysis: State of the Art

    Science.gov (United States)

    García-Campos, Miguel A.; Espinal-Enríquez, Jesús; Hernández-Lemus, Enrique

    2015-01-01

    Pathway analysis is a set of widely used tools for research in life sciences intended to give meaning to high-throughput biological data. The methodology of these tools settles in the gathering and usage of knowledge that comprise biomolecular functioning, coupled with statistical testing and other algorithms. Despite their wide employment, pathway analysis foundations and overall background may not be fully understood, leading to misinterpretation of analysis results. This review attempts to comprise the fundamental knowledge to take into consideration when using pathway analysis as a hypothesis generation tool. We discuss the key elements that are part of these methodologies, their capabilities and current deficiencies. We also present an overview of current and all-time popular methods, highlighting different classes across them. In doing so, we show the exploding diversity of methods that pathway analysis encompasses, point out commonly overlooked caveats, and direct attention to a potential new class of methods that attempt to zoom the analysis scope to the sample scale. PMID:26733877

  10. Koopmans' Analysis of Chemical Hardness with Spectral-Like Resolution

    Science.gov (United States)

    2013-01-01

    Three approximation levels of Koopmans' theorem are explored and applied: the first referring to the inner quantum behavior of the orbitalic energies that depart from the genuine ones in Fock space when the wave-functions' Hilbert-Banach basis set is specified to solve the many-electronic spectra of spin-orbitals' eigenstates; it is the most subtle issue regarding Koopmans' theorem as it brings many critics and refutation in the last decades, yet it is shown here as an irrefutable “observational” effect through computation, specific to any in silico spectra of an eigenproblem; the second level assumes the “frozen spin-orbitals” approximation during the extracting or adding of electrons to the frontier of the chemical system through the ionization and affinity processes, respectively; this approximation is nevertheless workable for great deal of chemical compounds, especially organic systems, and is justified for chemical reactivity and aromaticity hierarchies in an homologue series; the third and the most severe approximation regards the extension of the second one to superior orders of ionization and affinities, here studied at the level of chemical hardness compact-finite expressions up to spectral-like resolution for a paradigmatic set of aromatic carbohydrates. PMID:23970834

  11. Koopmans' Analysis of Chemical Hardness with Spectral-Like Resolution

    Directory of Open Access Journals (Sweden)

    Mihai V. Putz

    2013-01-01

    Full Text Available Three approximation levels of Koopmans' theorem are explored and applied: the first referring to the inner quantum behavior of the orbitalic energies that depart from the genuine ones in Fock space when the wave-functions' Hilbert-Banach basis set is specified to solve the many-electronic spectra of spin-orbitals' eigenstates; it is the most subtle issue regarding Koopmans' theorem as it brings many critics and refutation in the last decades, yet it is shown here as an irrefutable “observational” effect through computation, specific to any in silico spectra of an eigenproblem; the second level assumes the “frozen spin-orbitals” approximation during the extracting or adding of electrons to the frontier of the chemical system through the ionization and affinity processes, respectively; this approximation is nevertheless workable for great deal of chemical compounds, especially organic systems, and is justified for chemical reactivity and aromaticity hierarchies in an homologue series; the third and the most severe approximation regards the extension of the second one to superior orders of ionization and affinities, here studied at the level of chemical hardness compact-finite expressions up to spectral-like resolution for a paradigmatic set of aromatic carbohydrates.

  12. Portfolio Assessment on Chemical Reactor Analysis and Process Design Courses

    Science.gov (United States)

    Alha, Katariina

    2004-01-01

    Assessment determines what students regard as important: if a teacher wants to change students' learning, he/she should change the methods of assessment. This article describes the use of portfolio assessment on five courses dealing with chemical reactor and process design during the years 1999-2001. Although the use of portfolio was a new…

  13. Toxic hazard and chemical analysis of leachates from furfurylated wood

    NARCIS (Netherlands)

    Pilgard, A.; Treu, A.; Zeeland, van A.N.T.; Gosselink, R.J.A.; Westin, M.

    2010-01-01

    The furfurylation process is an extensively investigated wood modification process. Furfuryl alcohol molecules penetrate into the wood cell wall and polymerize in situ. This results in a permanent swelling of the wood cell walls. It is unclear whether or not chemical bonds exist between the furfuryl

  14. Probabilistic thermo-chemical analysis of a pultruded composite rod

    DEFF Research Database (Denmark)

    Baran, Ismet; Tutum, Cem Celal; Hattel, Jesper Henri

    2012-01-01

    In the present study the deterministic thermo-chemical pultrusion simulation of a composite rod taken from the literature [7] is used as a validation case. The predicted centerline temperature and cure degree profiles of the rod match well with those in the literature [7]. Following the validation...

  15. Probabilistic thermo-chemical analysis of a pultruded composite rod

    NARCIS (Netherlands)

    Baran, Ismet; Tutum, Cem C.; Hattel, Jesper H.

    2012-01-01

    In the present study the deterministic thermo-chemical pultrusion simulation of a composite rod taken from the literature [7] is used as a validation case. The predicted centerline temperature and cure degree profiles of the rod match well with those in the literature [7]. Following the validation c

  16. Chemical and non-chemical s tressors affecting childhood obesity: a state-of-the-science-review

    Science.gov (United States)

    Childhood obesity has tripled in the last three decades and now affects 17% of children in the United States (US). In 2010, the percentage of obese children in the US was nearly 18% for both 6-11 and 12-19 years of age. Recent evidence in the literature suggests that exposure to ...

  17. Steady State Analysis of Towed Marine Cables

    Institute of Scientific and Technical Information of China (English)

    WANG Fei; HUANG Guo-liang; DENG De-heng

    2008-01-01

    Efficient numerical schemes were presented for the steady state solutions of towed marine cables. For most of towed systems, the steady state problem can be resolved into two-point boundary-value problem, or initial value problem in some special cases where the initial values are available directly. A new technique was proposed and attempted to solve the two-point boundary-value problem rather than the conventional shooting method due to its algorithm complexity and low efficiency. First, the boundary conditions are transformed into a set of nonlinear governing equations about the initial values, then bisection method is employed to solve these nonlinear equations with the aid of 4th order Runge-Kutta method. In common sense, non-uniform (sheared) current is assumed, which varies in magnitude and direction with depth. The schemes are validated through the DE Zoysa's example, then several numerical examples are also presented to illustrate the numerical schemes.

  18. Laser-induced fluorescence: quantitative analysis of atherosclerotic plaque chemical content in human aorta

    Science.gov (United States)

    Dai, Erbin; Wishart, David; Khoury, Samir; Kay, Cyril M.; Jugdutt, Bodh I.; Tulip, John; Lucas, Alexandra

    1996-05-01

    We have been studying laser-induced fluorescence as a technique for identification of selected changes in the chemical composition of atherosclerotic plaque. Formulae for quantification of chemical changes have been developed based upon analysis of fluorescence emission spectra using multiple regression analysis and the principal of least squares. The intima of human aortic necropsy specimens was injected with chemical compounds present in atherosclerotic plaque. Spectra recorded after injection of selected chemical components found in plaque (collagen I, III, IV, elastin and cholesterol) at varying concentrations (0.01 - 1.0 mg) were compared with saline injection. A single fiber system was used for both fluorescence excitation (XeCl excimer laser, 308 nm, 1.5 - 2.0 mJ/ pulse, 5 Hz) and fluorescence emission detection. Average spectra for each chemical have been developed and the wavelengths of peak emission intensity identified. Curve fitting analysis as well as multiple regression analysis were used to develop formulae for assessment of chemical content. Distinctive identifying average curves were established for each chemical. Excellent correlations were identified for collagen I, III, and IV, elastin, and cholesterol (R2 equals 0.92 6- 0.997). Conclusions: (1) Fluorescence spectra of human aortas were significantly altered by collagen I, collagen III, elastin and cholesterol. (2) Fluorescence spectroscopic analysis may allow quantitative assessment of atherosclerotic plaque chemical content in situ.

  19. High resolution Physio-chemical Tissue Analysis: Towards Non-invasive In Vivo Biopsy

    Science.gov (United States)

    Xu, Guan; Meng, Zhuo-Xian; Lin, Jian-Die; Deng, Cheri X.; Carson, Paul L.; Fowlkes, J. Brian; Tao, Chao; Liu, Xiaojun; Wang, Xueding

    2016-02-01

    Conventional gold standard histopathologic diagnosis requires information of both high resolution structural and chemical changes in tissue. Providing optical information at ultrasonic resolution, photoacoustic (PA) technique could provide highly sensitive and highly accurate tissue characterization noninvasively in the authentic in vivo environment, offering a replacement for histopathology. A two-dimensional (2D) physio-chemical spectrogram (PCS) combining micrometer to centimeter morphology and chemical composition simultaneously can be generated for each biological sample with PA measurements at multiple optical wavelengths. This spectrogram presents a unique 2D “physio-chemical signature” for any specific type of tissue. Comprehensive analysis of PCS, termed PA physio-chemical analysis (PAPCA), can lead to very rich diagnostic information, including the contents of all relevant molecular and chemical components along with their corresponding histological microfeatures, comparable to those accessible by conventional histology. PAPCA could contribute to the diagnosis of many diseases involving diffusive patterns such as fatty liver.

  20. CHEMICAL ANALYSIS OF DENSE-GAS EXTRACTS FROM LIME FLOWERS

    Directory of Open Access Journals (Sweden)

    Demyanenko DV

    2015-04-01

    Full Text Available The purpose of this work was to make qualitative and quantitative analysis of phenolic biologically active substances (BAS in the extracts produced from lime flowers with condensed gases, using method of high-performance liquid chromatography (HPLC. Materials and methods: materials for this study were the extracts obtained by consequent processing of the herbal drug and marcs thereof with various condensed gases: difluorochloromethane (Freon R22, difluoromethane (Freon R32, azeotropic mixture of difluoromethane with pentafluoroethane (Freon 410A and freon-ammonium mixture. Extracts obtained with the latter were subjected to further fractionation by liquidliquid separation into hexane, chloroform, ethyl acetate and aqueous-alcohol phases. Besides, the supercritical СО2 extract, obtained from the herbal drug under rather strong conditions (at temperature 60°С and pressure 400 bar, was studied in our previous research. Presence of phenolic BAS and their quantity in the researched samples were determined by method of HPLC with UVspectrometric detection. Results and discussion: It has been found that Freon R22 extracted trace amounts of rutin from lime flowers – its content was only 0.08% of the total extract weight. On the other hand, Freons R32 and R410А showed good selectivity to moderately polar BAS of lime flowers (derivatives of flavonoids and hydroxycinnamic acids: in particular, the extract obtained with freon R32 contained about 1.3% of the total phenolic substances, and it was the only one of the investigated condensed gases used by us which took the basic flavonoid of lime flowers tiliroside – its content was 0.42% of extract weight. Also Freons R32 and R410А were able to withdraw another compound dominating among phenolic substances in the yielded extracts. Its quantity was rather noticeable – up to 0.87% of extract weight. This substance was not identified by existing database, but its UV-spectrum was similar to those of

  1. RELIABILITY ANALYSIS FOR IMPLICIT LIMIT STATE EQUATION

    Institute of Scientific and Technical Information of China (English)

    WANG Yan-ping; L(U) Zhen-zhou; YUE Zhu-feng

    2005-01-01

    In order to obtain the failure probability of the implicit limit state equation accurately, advanced mean value second order (AMVSO) method was presented, and advanced mean value (AMV) in conjunction with the response surface method (RSM)was also presented. The implementations were constructed on the basis of the advanced mean value first order (AMVFO) method and the RSM. The examples show that the accuracy of the AMVSO is higher than that of the AMVFO. The results of the AMV in conjunction with the RSM are not sensitive to the positions of the sampling points for determining the response surface equation, which illustrates the robustness of the presented method.

  2. THE BACTERIOLOGICAL AND PHYSICO-CHEMICAL STUDIES ON OLUMIRIN WATERFALL ERIN- IJESHA, OSUN STATE, NIGERIA

    Directory of Open Access Journals (Sweden)

    Oluwakemi Akindolapo

    2011-10-01

    Full Text Available The potability and qualities of Olumirin waterfall, Erin-Ijesa were investigated by determining the total bacteria and coliform count with antibiotic susceptibility of the isolated bacteria and physico-chemical qualities of the water samples. Total bacteria and coliform enumeration were determined using pour plating and multiple tube techniques, the antibiotic susceptibility were carried out using disc diffusion method, while physico-chemical and mineral studies were also carried out using standard methods. The mean total viable count of the water samples ranged 14.8 x 102 CFU.ml-1 - 21.3 x 103 CFU.ml-1 while the coliform count ranged 13 -175 MPN/100ml. The identified bacteria isolates and their percentage distribution were E.coli (43.1%, Klebsiella spp (20.7%, Proteus spp (12.1%, Salmonella spp (6.99%, Pseudomonas spp (5.17%, Shigella spp (6.9%, and Enterococcus spp (5.17 %. Antibiotic resistance shown by bacteria isolates were exhibited as follow; Nalixidic acid (31%, Ampicilin (76%, Cotrimoxazole (60%, Gentamicin (19%, Nitrofurantoin (24%, Colitin (48%, Streptomycin (34% and tetracycline (52%. 82.8% of the isolate exhibited multiple antibiotic resistance. The physico-chemical analysis also revealed the presence of some mineral elements in the water samples. The mineral value of the water samples include; magnesium (84.8 - 93.4 mg.L-1, phosphate (12.6 - 17.1 mg.L-1, sodium (47.8 - 87.6 mg.L-1, potassium (76.6 - 104.5 mg.L-1, chloride (59.0 - 90.2 mg.L-1, zinc (0.75 - 1.82 mg.L-1, lead (0.12 - 0.33 mg.L-1, iron (0.52 - 0.60 mg.L-1, copper (0.12 - 0.27 mg.L-1 while nickel and arsenic were not detected in any of the water samples. Comparing the experimental results with the international water standard for natural water, the waterfall is not fit for consumption or for any domestic purpose unless being treated. Also, problems that may arise from the resistance bacteria strains can be tackled while the new antibiotics can also be developed.

  3. Chemical Bonding States of TiC Films before and after Hydrogen Ion Irradiation

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    TiC films deposited by rf magnetron sputtering followed by Ar+ ion bombardment were irradiated with a hydrogen ion beam. X-ray photoelectron spectroscopy (XPS) was used for characterization of the chemical bonding states of C and Ti elements of the TiC films before and after hydrogen ion irradiation, in order to understand the effect of hydrogen ion irradiation on the films and to study the mechanism of hydrogen resistance of TiC films. Conclusions can be drawn that ion bombardment at moderate energy can cause preferential physical sputtering of carbon atoms from the surface of low atomic number (Z) material. This means that ion beam bombardment leads to the formation of a non-stoichiometric composition of TiC on the surface.TiC films prepared by ion beam mixing have the more excellent characteristic of hydrogen resistance. One important cause, in addition to TiC itself, is that there are many vacant sites in TiC created by ion beam mixing.These defects can easily trap hydrogen and effectively enhance the effect of hydrogen resistance.

  4. Rate constants of chemical reactions from semiclassical transition state theory in full and one dimension.

    Science.gov (United States)

    Greene, Samuel M; Shan, Xiao; Clary, David C

    2016-06-28

    Semiclassical Transition State Theory (SCTST), a method for calculating rate constants of chemical reactions, offers gains in computational efficiency relative to more accurate quantum scattering methods. In full-dimensional (FD) SCTST, reaction probabilities are calculated from third and fourth potential derivatives along all vibrational degrees of freedom. However, the computational cost of FD SCTST scales unfavorably with system size, which prohibits its application to larger systems. In this study, the accuracy and efficiency of 1-D SCTST, in which only third and fourth derivatives along the reaction mode are used, are investigated in comparison to those of FD SCTST. Potential derivatives are obtained from numerical ab initio Hessian matrix calculations at the MP2/cc-pVTZ level of theory, and Richardson extrapolation is applied to improve the accuracy of these derivatives. Reaction barriers are calculated at the CCSD(T)/cc-pVTZ level. Results from FD SCTST agree with results from previous theoretical and experimental studies when Richardson extrapolation is applied. Results from our implementation of 1-D SCTST, which uses only 4 single-point MP2/cc-pVTZ energy calculations in addition to those for conventional TST, agree with FD results to within a factor of 5 at 250 K. This degree of agreement and the efficiency of the 1-D method suggest its potential as a means of approximating rate constants for systems too large for existing quantum scattering methods.

  5. Finite state projection based bounds to compare chemical master equation models using single-cell data

    Science.gov (United States)

    Fox, Zachary; Neuert, Gregor; Munsky, Brian

    2016-08-01

    Emerging techniques now allow for precise quantification of distributions of biological molecules in single cells. These rapidly advancing experimental methods have created a need for more rigorous and efficient modeling tools. Here, we derive new bounds on the likelihood that observations of single-cell, single-molecule responses come from a discrete stochastic model, posed in the form of the chemical master equation. These strict upper and lower bounds are based on a finite state projection approach, and they converge monotonically to the exact likelihood value. These bounds allow one to discriminate rigorously between models and with a minimum level of computational effort. In practice, these bounds can be incorporated into stochastic model identification and parameter inference routines, which improve the accuracy and efficiency of endeavors to analyze and predict single-cell behavior. We demonstrate the applicability of our approach using simulated data for three example models as well as for experimental measurements of a time-varying stochastic transcriptional response in yeast.

  6. Evaluating chemical extraction techniques for the determination of uranium oxidation state in reduced aquifer sediments.

    Science.gov (United States)

    Stoliker, Deborah L; Campbell, Kate M; Fox, Patricia M; Singer, David M; Kaviani, Nazila; Carey, Minna; Peck, Nicole E; Bargar, John R; Kent, Douglas B; Davis, James A

    2013-08-20

    Extraction techniques utilizing high pH and (bi)carbonate concentrations were evaluated for their efficacy in determining the oxidation state of uranium (U) in reduced sediments collected from Rifle, CO. Differences in dissolved concentrations between oxic and anoxic extractions have been proposed as a means to quantify the U(VI) and U(IV) content of sediments. An additional step was added to anoxic extractions using a strong anion exchange resin to separate dissolved U(IV) and U(VI). X-ray spectroscopy showed that U(IV) in the sediments was present as polymerized precipitates similar to uraninite and/or less ordered U(IV), referred to as non-uraninite U(IV) species associated with biomass (NUSAB). Extractions of sediment containing both uraninite and NUSAB displayed higher dissolved uranium concentrations under oxic than anoxic conditions while extractions of sediment dominated by NUSAB resulted in identical dissolved U concentrations. Dissolved U(IV) was rapidly oxidized under anoxic conditions in all experiments. Uraninite reacted minimally under anoxic conditions but thermodynamic calculations show that its propensity to oxidize is sensitive to solution chemistry and sediment mineralogy. A universal method for quantification of U(IV) and U(VI) in sediments has not yet been developed but the chemical extractions, when combined with solid-phase characterization, have a narrow range of applicability for sediments without U(VI).

  7. Evaluating chemical extraction techniques for the determination of uranium oxidation state in reduced aquifer sediments

    Science.gov (United States)

    Stoliker, Deborah L.; Campbell, Kate M.; Fox, Patricia M.; Singer, David M.; Kaviani, Nazila; Carey, Minna; Peck, Nicole E.; Barger, John R.; Kent, Douglas B.; Davis, James A.

    2013-01-01

    Extraction techniques utilizing high pH and (bi)carbonate concentrations were evaluated for their efficacy in determining the oxidation state of uranium (U) in reduced sediments collected from Rifle, CO. Differences in dissolved concentrations between oxic and anoxic extractions have been proposed as a means to quantify the U(VI) and U(IV) content of sediments. An additional step was added to anoxic extractions using a strong anion exchange resin to separate dissolved U(IV) and U(VI). X-ray spectroscopy showed that U(IV) in the sediments was present as polymerized precipitates similar to uraninite and/or less ordered U(IV), referred to as non-uraninite U(IV) species associated with biomass (NUSAB). Extractions of sediment containing both uraninite and NUSAB displayed higher dissolved uranium concentrations under oxic than anoxic conditions while extractions of sediment dominated by NUSAB resulted in identical dissolved U concentrations. Dissolved U(IV) was rapidly oxidized under anoxic conditions in all experiments. Uraninite reacted minimally under anoxic conditions but thermodynamic calculations show that its propensity to oxidize is sensitive to solution chemistry and sediment mineralogy. A universal method for quantification of U(IV) and U(VI) in sediments has not yet been developed but the chemical extractions, when combined with solid-phase characterization, have a narrow range of applicability for sediments without U(VI).

  8. Assessment of chemical exchange in tryptophan–albumin solution through {sup 19}F multicomponent transverse relaxation dispersion analysis

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Ping-Chang, E-mail: pingchang.lin@howard.edu [Howard University, Department of Radiology, College of Medicine (United States)

    2015-06-15

    A number of NMR methods possess the capability of probing chemical exchange dynamics in solution. However, certain drawbacks limit the applications of these NMR approaches, particularly, to a complex system. Here, we propose a procedure that integrates the regularized nonnegative least squares (NNLS) analysis of multiexponential T{sub 2} relaxation into Carr–Purcell–Meiboom–Gill (CPMG) relaxation dispersion experiments to probe chemical exchange in a multicompartmental system. The proposed procedure was validated through analysis of {sup 19}F T{sub 2} relaxation data of 6-fluoro-DL-tryptophan in a two-compartment solution with and without bovine serum albumin. Given the regularized NNLS analysis of a T{sub 2} relaxation curve acquired, for example, at the CPMG frequency υ{sub CPMG} = 125, the nature of two distinct peaks in the associated T{sub 2} distribution spectrum indicated 6-fluoro-DL-tryptophan either retaining the free state, with geometric mean */multiplicative standard deviation (MSD) = 1851.2 ms */1.51, or undergoing free/albumin-bound interconversion, with geometric mean */MSD = 236.8 ms */1.54, in the two-compartment system. Quantities of the individual tryptophan species were accurately reflected by the associated T{sub 2} peak areas, with an interconversion state-to-free state ratio of 0.45 ± 0.11. Furthermore, the CPMG relaxation dispersion analysis estimated the exchange rate between the free and albumin-bound states in this fluorinated tryptophan analog and the corresponding dissociation constant of the fluorinated tryptophan–albumin complex in the chemical-exchanging, two-compartment system.

  9. Generalized molybdenum oxide surface chemical state XPS determination via informed amorphous sample model

    Energy Technology Data Exchange (ETDEWEB)

    Baltrusaitis, Jonas, E-mail: job314@lehigh.edu [Department of Chemical Engineering, Lehigh University, B336 Iacocca Hall, 111 Research Drive, Bethlehem, PA 18015 (United States); PhotoCatalytic Synthesis group, MESA+ Institute for Nanotechnology, Faculty of Science and Technology, University of Twente, Meander 229, P.O. Box 217, 7500 AE Enschede (Netherlands); Mendoza-Sanchez, Beatriz [CRANN, Chemistry School, Trinity College Dublin, Dublin (Ireland); Fernandez, Vincent [Institut des Matériaux Jean Rouxel, 2 rue de la Houssinière, BP 32229, F-44322 Nantes Cedex 3 (France); Veenstra, Rick [PhotoCatalytic Synthesis group, MESA+ Institute for Nanotechnology, Faculty of Science and Technology, University of Twente, Meander 229, P.O. Box 217, 7500 AE Enschede (Netherlands); Dukstiene, Nijole [Department of Physical and Inorganic Chemistry, Kaunas University of Technology, Radvilenu pl. 19, LT-50254 Kaunas (Lithuania); Roberts, Adam [Kratos Analytical Ltd, Trafford Wharf Road, Wharfside, Manchester, M17 1GP (United Kingdom); Fairley, Neal [Casa Software Ltd, Bay House, 5 Grosvenor Terrace, Teignmouth, Devon TQ14 8NE (United Kingdom)

    2015-01-30

    Highlights: • We analyzed and modeled spectral envelopes of complex molybdenum oxides. • Molybdenum oxide films of varying valence and crystallinity were synthesized. • MoO{sub 3} and MoO{sub 2} line shapes from experimental data were created. • Informed amorphous sample model (IASM) developed. • Amorphous molybdenum oxide XPS envelopes were interpreted. - Abstract: Accurate elemental oxidation state determination for the outer surface of a complex material is of crucial importance in many science and engineering disciplines, including chemistry, fundamental and applied surface science, catalysis, semiconductors and many others. X-ray photoelectron spectroscopy (XPS) is the primary tool used for this purpose. The spectral data obtained, however, is often very complex and can be subject to incorrect interpretation. Unlike traditional XPS spectra fitting procedures using purely synthetic spectral components, here we develop and present an XPS data processing method based on vector analysis that allows creating XPS spectral components by incorporating key information, obtained experimentally. XPS spectral data, obtained from series of molybdenum oxide samples with varying oxidation states and degree of crystallinity, were processed using this method and the corresponding oxidation states present, as well as their relative distribution was elucidated. It was shown that monitoring the evolution of the chemistry and crystal structure of a molybdenum oxide sample due to an invasive X-ray probe could be used to infer solutions to complex spectral envelopes.

  10. Generalized molybdenum oxide surface chemical state XPS determination via informed amorphous sample model

    Science.gov (United States)

    Baltrusaitis, Jonas; Mendoza-Sanchez, Beatriz; Fernandez, Vincent; Veenstra, Rick; Dukstiene, Nijole; Roberts, Adam; Fairley, Neal

    2015-01-01

    Accurate elemental oxidation state determination for the outer surface of a complex material is of crucial importance in many science and engineering disciplines, including chemistry, fundamental and applied surface science, catalysis, semiconductors and many others. X-ray photoelectron spectroscopy (XPS) is the primary tool used for this purpose. The spectral data obtained, however, is often very complex and can be subject to incorrect interpretation. Unlike traditional XPS spectra fitting procedures using purely synthetic spectral components, here we develop and present an XPS data processing method based on vector analysis that allows creating XPS spectral components by incorporating key information, obtained experimentally. XPS spectral data, obtained from series of molybdenum oxide samples with varying oxidation states and degree of crystallinity, were processed using this method and the corresponding oxidation states present, as well as their relative distribution was elucidated. It was shown that monitoring the evolution of the chemistry and crystal structure of a molybdenum oxide sample due to an invasive X-ray probe could be used to infer solutions to complex spectral envelopes.

  11. New crosslinkers for electrospun chitosan fibre mats. I. Chemical analysis

    OpenAIRE

    Austero, Marjorie S.; Donius, Amalie E.; Wegst, Ulrike G.K.; Schauer, Caroline L.

    2012-01-01

    Chitosan (CS), the deacetylated form of chitin, the second most abundant, natural polysaccharide, is attractive for applications in the biomedical field because of its biocompatibility and resorption rates, which are higher than chitin. Crosslinking improves chemical and mechanical stability of CS. Here, we report the successful utilization of a new set of crosslinkers for electrospun CS. Genipin, hexamethylene-1,6-diaminocarboxysulphonate (HDACS) and epichlorohydrin (ECH) have not been previ...

  12. Relational database driven two-dimensional chemical graph analysis.

    Science.gov (United States)

    Wilkens, Steven J

    2006-09-01

    This manuscript presents a method for pre-computing and storing molecular features or ''scaffolds'' that can be used for rapid clustering of diverse compound sets within the context of a relational database based on hierarchies of scaffold structures. In addition, a method for rapid structure-based profiling of a large compound collection is demonstrated. Pre-organizing compounds by shared structural features in this way facilitates the merger of chemical features and biological data within a relational database.

  13. Tattoo inks: legislation, pigments, metals and chemical analysis.

    Science.gov (United States)

    Prior, Gerald

    2015-01-01

    Legal limits for chemical substances require that they are linked to clearly defined analytical methods. Present limits for certain chemicals in tattoo and permanent make-up inks do not mention analytical methods for the detection of metals, polycyclic aromatic hydrocarbons or forbidden colourants. There is, therefore, no established method for the determination of the quantities of these chemicals in tattoo and permanent make-up inks. Failing to provide an appropriate method may lead to unqualified and questionable results which often cause legal disputes that are ultimately resolved by a judge with regard to the method that should have been applied. Analytical methods are tuned to exactly what is to be found and what causes the health problems. They are extremely specific. Irrespective of which is the correct method for detecting metals in tattoo inks, the focus should be on the actual amounts of ink in the skin. CTL® has conducted experiments to determine these amounts and these experiments are crucial for toxicological evaluations and for setting legal limits. When setting legal limits, it is essential to also incorporate factors such as daily consumption, total uptake and frequency of use. A tattoo lasts for several decades; therefore, the limits that have been established for heavy metals used in drinking water or soap are not relevant. Drinking water is consumed on a daily basis and soap is used several times per week, while tattooing only occurs once.

  14. Chemical Analysis of Emu Feather Fiber Reinforced Epoxy Composites

    Directory of Open Access Journals (Sweden)

    V.Chandra sekhar

    2015-07-01

    Full Text Available A composite is usually made up of at least two materials out of which one is binding material called as matrix and other is a reinforcement material known as fiber. For the past ten years research is going on to explore possible composites with natural fiber like plant fibers and animal fibers. The important characteristics of composites are their strength, hardness light in weight. It is also necessary to study about the resistance of the composites for deferent chemicals. In the present work, composites prepared with epoxy (Araldite LY-556 as resin and „emu‟ bird feathers as fiber have been tested for chemical resistance. The composites were prepared by varying fiber loading (P of „emu‟ feathers ranging from 1 to 5 and length (L of feather fibers from 1 to 5 cm. The composites thus prepared were subjected to various chemicals (Acids, Alkalis, solvents etc.. Observations were plotted and studied. The results reveal that there will be weight gain for the composite samples after three days, when treated with Hydrochloric acid, Sodium carbonate, Acetic acid, Sodium hydroxide, Nitric acid and Ammonium hydroxide. Weight loss was observed for all the samples including pure epoxy when treated with Benzene, Carbon tetra chloride and Toluene.

  15. Miniaturised wireless smart tag for optical chemical analysis applications.

    Science.gov (United States)

    Steinberg, Matthew D; Kassal, Petar; Tkalčec, Biserka; Murković Steinberg, Ivana

    2014-01-01

    A novel miniaturised photometer has been developed as an ultra-portable and mobile analytical chemical instrument. The low-cost photometer presents a paradigm shift in mobile chemical sensor instrumentation because it is built around a contactless smart card format. The photometer tag is based on the radio-frequency identification (RFID) smart card system, which provides short-range wireless data and power transfer between the photometer and a proximal reader, and which allows the reader to also energise the photometer by near field electromagnetic induction. RFID is set to become a key enabling technology of the Internet-of-Things (IoT), hence devices such as the photometer described here will enable numerous mobile, wearable and vanguard chemical sensing applications in the emerging connected world. In the work presented here, we demonstrate the characterisation of a low-power RFID wireless sensor tag with an LED/photodiode-based photometric input. The performance of the wireless photometer has been tested through two different model analytical applications. The first is photometry in solution, where colour intensity as a function of dye concentration was measured. The second is an ion-selective optode system in which potassium ion concentrations were determined by using previously well characterised bulk optode membranes. The analytical performance of the wireless photometer smart tag is clearly demonstrated by these optical absorption-based analytical experiments, with excellent data agreement to a reference laboratory instrument.

  16. Sample preparation for combined chemical analysis and bioassay application in water quality assessment

    NARCIS (Netherlands)

    Kolkman, A.; Schriks, M.; Brand, W; Bäuerlein, P.S.; van der Kooi, M.M.E.; van Doorn, R.H.; Emke, E.; Reus, A.; van der Linden, S.; de Voogt, P.; Heringa, M.B.

    2013-01-01

    The combination of in vitro bioassays and chemical screening can provide a powerful toolbox to determine biologically relevant compounds in water extracts. In this study, a sample preparation method is evaluated for the suitability for both chemical analysis and in vitro bioassays. A set of 39 chemi

  17. Analysis of solids remaining following chemical cleaning in tank 6F

    Energy Technology Data Exchange (ETDEWEB)

    Poirier, Michael R. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Fondeur, Fernando F. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Missimer, David M. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Summer, Michael E. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Fink, Samuel D. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2010-02-05

    Following chemical cleaning, a solid sample was collected and submitted to Savannah River National Laboratory (SRNL) for analysis. SRNL analyzed this sample by X-ray Diffraction (XRD) and scanning electron microscopy (SEM) to determine the composition of the solids remaining in Tank 6F and to assess the effectiveness of the chemical cleaning process.

  18. Chemical or Biological Terrorist Attacks: An Analysis of the Preparedness of Hospitals for Managing Victims Affected by Chemical or Biological Weapons of Mass Destruction

    Directory of Open Access Journals (Sweden)

    Russell L. Bennett

    2006-03-01

    and analysis. Six hypotheses were tested. Using a questionnaire survey, the availability of functional preparedness plans, specific preparedness education/training, decontamination facilities, surge capacity, pharmaceutical supplies, and laboratory diagnostic capabilities of hospitals were examined. The findings revealed that a majority (89.2% of hospitals in the State of Mississippi have documented preparedness plans, provided specific preparedness education/training (89.2%, have dedicated facilities for decontamination (75.7%, and pharmaceutical plans and supplies (56.8% for the treatment of victims in the event of a disaster involving chemical or biological WMD. However, over half (59.5% of the hospitals could not increase surge capacity (supplies, equipment, staff, patient beds, etc. and lack appropriate laboratory diagnostic services (91.9% capable of analyzing and identifying WMD. In general, hospitals in the State of Mississippi, like a number of hospitals throughout the United States, are still not adequately prepared to manage victims of terrorist attacks involving chemical or biological WMD which consequently may result in the loss of hundreds or even thousands of lives. Therefore, hospitals continue to require substantial resources at the local, State, and national levels in order to be “truly” prepared.

  19. State-selected chemical reaction dynamics at the S matrix level - Final-state specificities of near-threshold processes at low and high energies

    Science.gov (United States)

    Chatfield, David C.; Truhlar, Donald G.; Schwenke, David W.

    1992-01-01

    State-to-state reaction probabilities are found to be highly final-state specific at state-selected threshold energies for the reactions O + H2 yield OH + H and H + H2 yield H2 + H. The study includes initial rotational states with quantum numbers 0-15, and the specificity is especially dramatic for the more highly rotationally excited reactants. The analysis is based on accurate quantum mechanical reactive scattering calculations. Final-state specificity is shown in general to increase with the rotational quantum number of the reactant diatom, and the trends are confirmed for both zero and nonzero values of the total angular momentum.

  20. Phase state of ambient aerosol linked with water uptake and chemical aging in the southeastern US

    Science.gov (United States)

    Pajunoja, Aki; Hu, Weiwei; Leong, Yu J.; Taylor, Nathan F.; Miettinen, Pasi; Palm, Brett B.; Mikkonen, Santtu; Collins, Don R.; Jimenez, Jose L.; Virtanen, Annele

    2016-09-01

    During the summer 2013 Southern Aerosol and Oxidant Study (SOAS) field campaign in a rural site in the southeastern United States, the effect of hygroscopicity and composition on the phase state of atmospheric aerosol particles dominated by the organic fraction was studied. The analysis is based on hygroscopicity measurements by a Hygroscopic Tandem Differential Mobility Analyzer (HTDMA), physical phase state investigations by an Aerosol Bounce Instrument (ABI) and composition measurements using a high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS). To study the effect of atmospheric aging on these properties, an OH-radical oxidation flow reactor (OFR) was used to simulate longer atmospheric aging times of up to 3 weeks. Hygroscopicity and bounce behavior of the particles had a clear relationship showing higher bounce at elevated relative humidity (RH) values for less hygroscopic particles, which agrees well with earlier laboratory studies. Additional OH oxidation of the aerosol particles in the OFR increased the O : C and the hygroscopicity resulting in liquefying of the particles at lower RH values. At the highest OH exposures, the inorganic fraction starts to dominate the bounce process due to production of inorganics and concurrent loss of organics in the OFR. Our results indicate that at typical ambient RH and temperature, organic-dominated particles stay mostly liquid in the atmospheric conditions in the southeastern US, but they often turn semisolid when dried below ˜ 50 % RH in the sampling inlets. While the liquid phase state suggests solution behavior and equilibrium partitioning for the SOA particles in ambient air, the possible phase change in the drying process highlights the importance of thoroughly considered sampling techniques of SOA particles.

  1. Mass spectrometry analysis of polychlorinated biphenyls: chemical ionization and selected ion chemical ionization using methane as a reagent gas

    Directory of Open Access Journals (Sweden)

    RAYMOND E. MARCH

    2000-06-01

    Full Text Available In the present paper a quadrupole ion trap mass spectrometer, coupled with a gas chromatograph, was used to compare the electron impact ionization (EI and chemical ionization (Cl technique, in terms of their selectivity in polychlorinated biphenyls (PCBs quantitative analysis. The experiments were carried out with a modified Varian SATURN III quadrupole ion-storage mass spectrometer equipped with Varian waveform generator, coupled with a gas chromatograph with DB-5 capillary column. The disadvantage of using EI in the analysis of PCBs congeners is the extensive fragmentation of the molecular ion. The main fragmentation pattern recorded in the EI mass spectra of PCBs was the loss of a chlorine atom from the molecular ion. Therefore the fragment-ion signal overlapped with the molecular-ion cluster of lower mass congener. The fragmentation reactions of PCBs are suppressed if methane is used as a reagent gas for chemical ionization, but fragment ions are also present in the spectrum as an obstruction for quantitative analysis. The most selective method for PCBs quantitative analysis appears to be Cl with mass-selected C2H5+ ions from methane, which results in a mass spectrum with a negligible amount of fragment ions.

  2. Statistically optimal analysis of state-discretized trajectory data from multiple thermodynamic states

    CERN Document Server

    Wu, Hao; Rosta, Edina; Noé, Frank

    2014-01-01

    We propose a discrete transition-based reweighting analysis method (dTRAM) for analyzing configuration-space-discretized simulation trajectories produced at different thermodynamic states (temperatures, Hamiltonians, etc.) dTRAM provides maximum-likelihood estimates of stationary quantities (probabilities, free energies, expectation values) at any thermodynamic state. In contrast to the weighted histogram analysis method (WHAM), dTRAM does not require data to be sampled from global equilibrium, and can thus produce superior estimates for enhanced sampling data such as parallel/simulated tempering, replica exchange, umbrella sampling, or metadynamics. In addition, dTRAM provides optimal estimates of Markov state models (MSMs) from the discretized state-space trajectories at all thermodynamic states. Under suitable conditions, these MSMs can be used to calculate kinetic quantities (e.g. rates, timescales). In the limit of a single thermodynamic state, dTRAM estimates a maximum likelihood reversible MSM, while i...

  3. Quality assessment of cortex cinnamomi by HPLC chemical fingerprint, principle component analysis and cluster analysis.

    Science.gov (United States)

    Yang, Jie; Chen, Li-Hong; Zhang, Qin; Lai, Mao-Xiang; Wang, Qiang

    2007-06-01

    HPLC fingerprint analysis, principle component analysis (PCA), and cluster analysis were introduced for quality assessment of Cortex cinnamomi (CC). The fingerprint of CC was developed and validated by analyzing 30 samples of CC from different species and geographic locations. Seventeen chromatographic peaks were selected as characteristic peaks and their relative peak areas (RPA) were calculated for quantitative expression of the HPLC fingerprints. The correlation coefficients of similarity in chromatograms were higher than 0.95 for the same species while much lower than 0.6 for different species. Besides, two principal components (PCs) have been extracted by PCA. PC1 separated Cinnamomum cassia from other species, capturing 56.75% of variance while PC2 contributed for their further separation, capturing 19.08% variance. The scores of the samples showed that the samples could be clustered reasonably into different groups corresponding to different species and different regions. The scores and loading plots together revealed different chemical properties of each group clearly. The cluster analysis confirmed the results of PCA analysis. Therefore, HPLC fingerprint in combination with chemometric techniques provide a very flexible and reliable method for quality assessment of traditional Chinese medicines.

  4. Content Analysis Concerning State Green Lodging Certification Programs in the United States

    OpenAIRE

    Yu, Yue

    2013-01-01

    The present thesis reports a content analysis study of state green lodging certification programs (SGLCPs) in the United States. The study explores how the government and industry associations operate and maintain SGLCPs. Through online research, the researcher found that 20 states have SGLCP. There are total 21 programs in operation currently. The study focused on the textual content of the 21 programs' websites. The study determined the rationale of SGLCPs adoption through analyzing prog...

  5. Evidence for excited-state intramolecular proton transfer in 4-chlorosalicylic acid from combined experimental and computational studies: Quantum chemical treatment of the intramolecular hydrogen bonding interaction

    Energy Technology Data Exchange (ETDEWEB)

    Paul, Bijan Kumar [Department of Chemistry, University of Calcutta, 92 Acharya Prafulla Chandra Road, Calcutta 700009 (India); Guchhait, Nikhil, E-mail: nikhil.guchhait@rediffmail.com [Department of Chemistry, University of Calcutta, 92 Acharya Prafulla Chandra Road, Calcutta 700009 (India)

    2012-07-25

    Highlights: Black-Right-Pointing-Pointer Experimental and computational studies on the photophysics of 4-chlorosalicylic acid. Black-Right-Pointing-Pointer Spectroscopically established ESIPT reaction substantiated by theoretical calculation. Black-Right-Pointing-Pointer Quantum chemical treatment of IMHB unveils strength, nature and directional nature. Black-Right-Pointing-Pointer Superiority of quantum chemical treatment of H-bond over geometric criteria. Black-Right-Pointing-Pointer Role of H-bond as a modulator of aromaticity. -- Abstract: The photophysical study of a pharmaceutically important chlorine substituted derivative of salicylic acid viz., 4-chlorosalicylic acid (4ClSA) has been carried out by steady-state absorption, emission and time-resolved emission spectroscopy. A large Stokes shifted emission band with negligible solvent polarity dependence marks the spectroscopic signature of excited-state intramolecular proton transfer (ESIPT) reaction in 4ClSA. Theoretical calculation by ab initio and Density Functional Theory methods yields results consistent with experimental findings. Theoretical potential energy surfaces predict the occurrence of proton transfer in S{sub 1}-state. Geometrical and energetic criteria, Atoms-In-Molecule topological parameters, Natural Bond Orbital population analysis have been exploited to evaluate the intramolecular hydrogen bond (IMHB) interaction and to explore its directional nature. The inter-correlation between aromaticity and resonance assisted H-bond is also discussed in this context. Our results unveil that the quantum chemical treatment is a more accurate tool to assess hydrogen bonding interaction in comparison to geometrical criteria.

  6. Quantum chemical characterization of low-lying excited states of an aryl peroxycarbonate: mechanistic implications for photodissociation.

    Science.gov (United States)

    Olsen, Seth; Schwarzer, Dirk; Troe, Jürgen; Smith, Sean C

    2010-04-01

    Recent experiments have revealed the existence of an excited state dissociative mechanism for certain peroxycarbonates, with the demonstration that the lifetime of the excited state matches the picosecond time scale for appearance of nascent carbon dioxide product. The data infer that the photoreaction proceeds via an effectively concerted three-body dissociation within the lifetime of the singlet excited state. Many other arylperoxides decay sequentially via [(aryloxy)carbonyl]oxy radical intermediates on nanosecond-microsecond time scales. Uncertainty as to the lifetime of the excited state relates to the character and the relative energetic ordering of states of the parent molecule, since the spectra and photochemistry imply that low-lying states may exist on each of the aryl, carbonate, and peroxide chemical functionalities. We employ many-body electronic structure calculations to determine the energies and characters of the low-lying valence states of a minimal aryl peroxycarbonate model germane to the above-mentioned experiments, methyl phenyl peroxycarbonate (MPC). Our results indicate that the lowest-lying state is an intrinsically nondissociative aryl pipi* excited state. We identify additional low-lying states that are expected to be dissociative in nature and propose that the time scales observed for the dissociation reaction may correspond to the time scale for transfer of excited state population to these states.

  7. Evolution analysis of the states of the EZ model

    Institute of Scientific and Technical Information of China (English)

    Chen Qing-Hua; Ding Yi-Ming; Dong Hong-Guang

    2009-01-01

    Based on suitable choice of states,this paper studies the stability of the equilibrium state of the EZ model by regarding the evolution of the EZ model as a Markov chain and by showing that the Markov chain is ergodic.The Markov analysis is applied to the EZ model with small number of agents,the exact equilibrium state for N=5 and numerical results for N=18 are obtained.

  8. States' Potential Enrollment of Adult Students: A Stochastic Frontier Analysis

    Science.gov (United States)

    Titus, Marvin A.; Pusser, Brian

    2011-01-01

    This study shows that financial aspects of state higher education policies, particularly tuition, have an impact on the level of enrollment of adult undergraduates within a state. This study also demonstrates how stochastic frontier analysis (SFA) can be utilized to examine the "potential" maximum enrollment of adult learners in…

  9. [Analysis of main chemical composition in hydrogenated rosin from Zhuzhou].

    Science.gov (United States)

    Duan, W G; Chen, X P; Wang, L L; Deng, S; Zhou, Y H; An, X N

    2001-01-01

    The acid fraction, the main part of the hydrogenated rosin produced by Zhuzhou Forest Chemicals Plant of China, was separated from neutral fraction by modified DEAE-Sephadex ion exchange chromatography and analyzed with GC-MS-DS technique by using DB-5 capillary column. Six dihydroabietic-type resin acids, four dihydropimaric/isopimaric-type resin acids and four tetrahydroabietic-type resin acids were identified. The hydrogenated rosin is composed mainly of 8-abietenoic acid, 18-abietanoic acid, 13-abietenoic acid, 8 alpha, 13 beta-abietanoic acid, 13 beta-8-abietenoic acid and 8-isopimarenoic acid etc.

  10. Analysis of Thermal Desorption System for the Chemical Treatment of Old Storages of Oil Based Mud

    OpenAIRE

    Tanweer Hussain; Abdul Rehman Memon; Javed Larik

    2013-01-01

    This paper presents an analysis for the chemical treatment of OBM (Oil Based Mud) used in the drilling process in the oil and gas industry. The analysis is based on OBM stored at ENI (Italian National Energy) gas fields at Bhit mount district Jamshoro since the last ten years that has been chemically and physically deteriorated. Characterization of various OBM samples was performed and these samples were processed in order to evaluate the best characteristics of the OBM for optimum treatment ...

  11. CHEMKIN-III: A FORTRAN chemical kinetics package for the analysis of gas-phase chemical and plasma kinetics

    Energy Technology Data Exchange (ETDEWEB)

    Kee, R.J.; Rupley, F.M.; Meeks, E.; Miller, J.A.

    1996-05-01

    This document is the user`s manual for the third-generation CHEMKIN package. CHEMKIN is a software package whose purpose is to facilitate the formation, solution, and interpretation of problems involving elementary gas-phase chemical kinetics. It provides a flexible and powerful tool for incorporating complex chemical kinetics into simulations of fluid dynamics. The package consists of two major software components: an Interpreter and a Gas-Phase Subroutine Library. The Interpreter is a program that reads a symbolic description of an elementary, user-specified chemical reaction mechanism. One output from the Interpreter is a data file that forms a link to the Gas-Phase Subroutine Library. This library is a collection of about 100 highly modular FORTRAN subroutines that may be called to return information on equations of state, thermodynamic properties, and chemical production rates. CHEMKIN-III includes capabilities for treating multi-fluid plasma systems, that are not in thermal equilibrium. These new capabilities allow researchers to describe chemistry systems that are characterized by more than one temperature, in which reactions may depend on temperatures associated with different species; i.e. reactions may be driven by collisions with electrons, ions, or charge-neutral species. These new features have been implemented in such a way as to require little or no changes to CHEMKIN implementation for systems in thermal equilibrium, where all species share the same gas temperature. CHEMKIN-III now has the capability to handle weakly ionized plasma chemistry, especially for application related to advanced semiconductor processing.

  12. Spatially organized dynamical states in chemical oscillator networks: synchronization, dynamical differentiation, and chimera patterns.

    Directory of Open Access Journals (Sweden)

    Mahesh Wickramasinghe

    Full Text Available Dynamical processes in many engineered and living systems take place on complex networks of discrete dynamical units. We present laboratory experiments with a networked chemical system of nickel electrodissolution in which synchronization patterns are recorded in systems with smooth periodic, relaxation periodic, and chaotic oscillators organized in networks composed of up to twenty dynamical units and 140 connections. The reaction system formed domains of synchronization patterns that are strongly affected by the architecture of the network. Spatially organized partial synchronization could be observed either due to densely connected network nodes or through the 'chimera' symmetry breaking mechanism. Relaxation periodic and chaotic oscillators formed structures by dynamical differentiation. We have identified effects of network structure on pattern selection (through permutation symmetry and coupling directness and on formation of hierarchical and 'fuzzy' clusters. With chaotic oscillators we provide experimental evidence that critical coupling strengths at which transition to identical synchronization occurs can be interpreted by experiments with a pair of oscillators and analysis of the eigenvalues of the Laplacian connectivity matrix. The experiments thus provide an insight into the extent of the impact of the architecture of a network on self-organized synchronization patterns.

  13. Study of multi-site chemical exchange in solution state by NMR: 1D experiments with multiply selective excitation

    Indian Academy of Sciences (India)

    Samanwita Pal

    2010-07-01

    Chemical exchange in solution state has been investigated traditionally by both 1D and 2D NMR, permitting the extraction of kinetic parameters (e.g. the spin-lattice relaxation time 1, the exchange rate constant and the activation parameters). This work demonstrates a simple 1D NMR approach employing multiply selective excitation to study multi-site exchange processes in solution, applying it to systems that exhibit three-site exchange. This approach involves simultaneous excitation of all - or a chosen subset of - the exchanging sites by using an appropriately modulated shaped radiofrequency pulse. The pulse sequence, as well as analysis is summarized. Significant features of the experiment, which relies on sign labelling of the exchanging sites, include considerably shorter experiment time compared to standard 2D exchange work, clear definition of the exchange time window and uniform pulse non-ideality effects for all the exchanging sites. Complete kinetic information is reported in the study of dynamic processes in superacid solutions of two weak bases, studied by 1H NMR. An analytical solution, leading to the determination of four rate parameters, is presented for proton exchange studies on these systems, which involve a mixture of two weak bases in arbitrary concentration ratio, and stoichiometric excess of the superacid.

  14. Environmental Impact Assessment for Socio-Economic Analysis of Chemicals

    DEFF Research Database (Denmark)

    Calow, Peter; Biddinger, G; Hennes, C;

    This report describes the requirements for, and illustrates the application of, a methodology for a socio-economic analysis (SEA) especially as it might be adopted in the framework of REACH.......This report describes the requirements for, and illustrates the application of, a methodology for a socio-economic analysis (SEA) especially as it might be adopted in the framework of REACH....

  15. New crosslinkers for electrospun chitosan fibre mats. I. Chemical analysis.

    Science.gov (United States)

    Austero, Marjorie S; Donius, Amalie E; Wegst, Ulrike G K; Schauer, Caroline L

    2012-10-07

    Chitosan (CS), the deacetylated form of chitin, the second most abundant, natural polysaccharide, is attractive for applications in the biomedical field because of its biocompatibility and resorption rates, which are higher than chitin. Crosslinking improves chemical and mechanical stability of CS. Here, we report the successful utilization of a new set of crosslinkers for electrospun CS. Genipin, hexamethylene-1,6-diaminocarboxysulphonate (HDACS) and epichlorohydrin (ECH) have not been previously explored for crosslinking of electrospun CS. In this first part of a two-part publication, we report the morphology, determined by field emission scanning electron microscopy (FESEM), and chemical interactions, determined by Fourier transform infrared microscopy, respectively. FESEM revealed that CS could successfully be electrospun from trifluoroacetic acid with genipin, HDACS and ECH added to the solution. Diameters were 267 ± 199 nm, 644 ± 359 nm and 896 ± 435 nm for CS-genipin, CS-HDACS and CS-ECH, respectively. Short- (15 min) and long-term (72 h) dissolution tests (T(600)) were performed in acidic, neutral and basic pHs (3, 7 and 12). Post-spinning activation by heat and base to enhance crosslinking of CS-HDACS and CS-ECH decreased the fibre diameters and improved the stability. In the second part of this publication, we report the mechanical properties of the fibres.

  16. Toxic hazard and chemical analysis of leachates from furfurylated wood.

    Science.gov (United States)

    Pilgård, Annica; Treu, Andreas; van Zeeland, Albert N T; Gosselink, Richard J A; Westin, Mats

    2010-09-01

    The furfurylation process is an extensively investigated wood modification process. Furfuryl alcohol molecules penetrate into the wood cell wall and polymerize in situ. This results in a permanent swelling of the wood cell walls. It is unclear whether or not chemical bonds exist between the furfuryl alcohol polymer and the wood. In the present study, five different wood species were used, both hardwoods and softwoods. They were treated with three different furfurylation procedures and leached according to three different leaching methods. The present study shows that, in general, the leachates from furfurylated wood have low toxicity. It also shows that the choice of leaching method is decisive for the outcome of the toxicity results. Earlier studies have shown that leachates from wood treated with furfuryl alcohol prepolymers have higher toxicity to Vibrio fischeri than leachates from wood treated with furfuryl alcohol monomers. This is probably attributable to differences in leaching of chemical compounds. The present study shows that this difference in the toxicity most likely cannot be attributed to maleic acid, furan, furfural, furfuryl alcohol, or 2-furoic acid. However, the difference might be caused by the two substances 5-hydroxymethylfurfural and 2,5-furandimethanol. The present study found no difference in the amount of leached furfuryl alcohol between leachates from furfurylated softwood and furfurylated hardwood species. Earlier studies have indicated differences in grafting of furfuryl alcohol to lignin. However, nothing was found in the present study that could support this. The leachates of furfurylated wood still need to be

  17. The influence of chemical composition and mixing state of Los Angeles urban aerosol on CCN number and cloud properties

    Directory of Open Access Journals (Sweden)

    M. J. Cubison

    2008-03-01

    Full Text Available The relationship between cloud condensation nuclei (CCN number and the physical and chemical properties of the atmospheric aerosol distribution is explored for a polluted urban data set from the Study of Organic Aerosols at Riverside I (SOAR-1 campaign conducted at Riverside, California, USA during summer 2005. The mixing state and, to a lesser degree, the average chemical composition are shown to be important parameters in determining the activation properties of those particles around the critical activation diameters for atmospherically-realistic supersaturation values. Closure between predictions and measurements of CCN number at several supersaturations is attempted by modeling a number of aerosol chemical composition and mixing state schemes of increasing complexity. It is shown that a realistic treatment of the state of mixing of the urban aerosol distribution is critical in order to eliminate model bias. Fresh emissions such as elemental carbon and small organic particles must be treated as non-activating and explicitly accounted for in the model scheme. The relative number concentration of these particles compared to inorganics and oxygenated organic compounds of limited hygroscopicity plays an important role in determining the CCN number. Furthermore, expanding the different composition/mixing state schemes to predictions of cloud droplet number concentration in a cloud parcel model highlights the dependence of cloud optical properties on the state of mixing and hygroscopic properties of the different aerosol modes, but shows that the relative differences between the different schemes are reduced compared to those from the CCN model.

  18. Nanoelectromechanical resonator arrays for ultrafast, gas-phase chromatographic chemical analysis.

    Science.gov (United States)

    Li, Mo; Myers, E B; Tang, H X; Aldridge, S J; McCaig, H C; Whiting, J J; Simonson, R J; Lewis, N S; Roukes, M L

    2010-10-13

    Miniaturized gas chromatography (GC) systems can provide fast, quantitative analysis of chemical vapors in an ultrasmall package. We describe a chemical sensor technology based on resonant nanoelectromechanical systems (NEMS) mass detectors that provides the speed, sensitivity, specificity, and size required by the microscale GC paradigm. Such NEMS sensors have demonstrated detection of subparts per billion (ppb) concentrations of a phosphonate analyte. By combining two channels of NEMS detection with an ultrafast GC front-end, chromatographic analysis of 13 chemicals was performed within a 5 s time window.

  19. Calculation of Equation of State of QCD at Finite Chemical Potential and Temperature

    Institute of Scientific and Technical Information of China (English)

    QIAO Qing-Peng; ZONG Hong-Shi; TANG Jian; HOU Feng-Yao; LI Xue-Qian; SUN Wei-Min; L(U) Xiao-Fu

    2008-01-01

    In this paper, using path integral techniques we derive a model-independent formula for the pressure density (μ, T) (or equivalently the partition function) of Quantum Chromodynamics (QCD), which gives the equation of state (EOS) of QCD at finite chemical potential and temperature. In this formula the pressure density (μ, T) consists of two terms: the first term (μ,T) T=0) is a #-independent (but T-dependent) constant; the second term is totally determined by G[μ, T] (p ωn) (the dressed quark propagator at finite μ and finite T), which contains all the nontrivial μ-dependence. Then, in the framework of the rainbow-ladder approximation of the Dyson-Schwinger (DS) approach and under the approximation of neglecting the μ-dependence of the dressed gluon propagator, we show that G[μ, T] (p, ωn) can be obtained from G[T] (p, ωn) (the dressed quark propagator at μ = 0) by the substitution ωn →ωn + iμ. This result facilitates numerical calculations considerably. By this result, once G[T](p, ωn) is known, one can determine the EOS of QCD under the above approximations (up to the additive term (μ, T)[T=0). Finally, a comparison of the present EOS of QCD and the EOS obtained in the previous literatures in the framework of the rainbow-ladder approximation of the DS approach is given. It is found that the EOS given in the previous literatures does not satisfy the thermodynamic relation p(μ, T) = T.

  20. Quantum chemical analysis of binary and ternary ferromagnetic alloys; Quantenchemische Untersuchungen binaerer und ternaerer ferromagnetischer Legierungen

    Energy Technology Data Exchange (ETDEWEB)

    Jacobs, Yasemin Erika Charlotte

    2007-02-23

    In this work the electronic structures, densities of states, chemical bonding, magnetic exchange Parameters and Curie temperatures of binary and ternary ferromagnetic alloys are analyzed. The electronic structure of ferromagnetic MnAl has been calculated using density-functional techniques (TB-LMTO-ASA, FPLAPW) and quantum chemically analyzed by means of the crystal orbital Hamilton population analysis. The crystal structure of the ferromagnetic tetragonal MnAl may be understood to originate from the structure of nonmagnetic cubic MnAl with a CsCl motif through a two-step process. While the nonmagnetic cubic structure is stable against a structural deformation, antibonding Mn-Mn interactions at the Fermi level lead to spin polarization and the onset of magnetism, i.e., a symmetry reduction taking place solely in the electronic degrees of freedom, by that emptying antibonding Mn-Mn states. Residual antibonding Al--Al states can only be removed by a subsequent, energetically smaller structural deformation towards the tetragonal system. As a final result, homonuclear bonding is strengthened and heteronuclear bonding is weakened. Corresponding DFT calculations of the electronic structure as well as the calculation of the chemical bonding and the magnetic exchange interactions have been performed on the basis of LDA and GGA for a series of ferromagnetic full Heusler alloys of general formula Co2MnZ (Z=Ga,Si,Ge,Sn), Rh2MnZ (Z=Ge,Sn,Pb), Ni2MnZ (Z=Ga,In,Sn), Pd2MnZ (Z=Sn,Sb) and Cu2MnZ (Z=Al,In,Sn). The connection between the electronic spectra and the magnetic interactions have been studied. Correlations between the chemical bondings in Heusler alloys derived from COHP analysis and magnetic phenomena are obvious, and different mechanisms leading to spin polarization and ferromagnetism are derived. The band dependence of the exchange parameters, their dependence on volume and valence electron concentration have been thoroughly analyzed within the Green function technique

  1. Biological Sampling and Analysis in Sinclair and Dyes Inlets, Washington: Chemical Analyses for 2007 Puget Sound Biota Study

    Energy Technology Data Exchange (ETDEWEB)

    Brandenberger, Jill M.; Suslick, Carolynn R.; Johnston, Robert K.

    2008-10-09

    Evaluating spatial and temporal trends in contaminant residues in Puget Sound fish and macroinvertebrates are the objectives of the Puget Sound Ambient Monitoring Program (PSAMP). In a cooperative effort between the ENVironmental inVESTment group (ENVVEST) and Washington State Department of Fish and Wildlife, additional biota samples were collected during the 2007 PSAMP biota survey and analyzed for chemical residues and stable isotopes of carbon (δ13C) and nitrogen (δ15N). Approximately three specimens of each species collected from Sinclair Inlet, Georgia Basin, and reference locations in Puget Sound were selected for whole body chemical analysis. The muscle tissue of specimens selected for chemical analyses were also analyzed for δ13C and δ15N to provide information on relative trophic level and food sources. This data report summarizes the chemical residues for the 2007 PSAMP fish and macro-invertebrate samples. In addition, six Spiny Dogfish (Squalus acanthias) samples were necropsied to evaluate chemical residue of various parts of the fish (digestive tract, liver, embryo, muscle tissue), as well as, a weight proportional whole body composite (WBWC). Whole organisms were homogenized and analyzed for silver, arsenic, cadmium, chromium, copper, nickel, lead, zinc, mercury, 19 polychlorinated biphenyl (PCB) congeners, PCB homologues, percent moisture, percent lipids, δ13C, and δ15N.

  2. Measurements of the aerosol chemical composition and mixing state in the Po Valley using multiple spectroscopic techniques

    Directory of Open Access Journals (Sweden)

    S. Decesari

    2014-04-01

    Full Text Available The use of co-located multiple spectroscopic techniques can provide detailed information on the atmospheric processes regulating aerosol chemical composition and mixing state. So far, field campaigns heavily equipped with aerosol mass spectrometers have been carried out mainly in large conurbations and in areas directly affected by their outflow, whereas lesser efforts have been dedicated to continental areas characterized by a less dense urbanization. We present here the results obtained in San Pietro Capofiume, which is located in a sparsely inhabited sector of the Po Valley, Italy. The experiment was carried out in summer 2009 in the framework of the EUCAARI project ("European Integrated Project on Aerosol, Cloud Climate Aerosol Interaction". For the first time in Europe, six state-of-the-art techniques were used in parallel: (1 on-line TSI aerosol time-of-flight mass spectrometer (ATOFMS, (2 on-line Aerodyne high-resolution time-of-flight aerosol mass spectrometer (HR-TOF-AMS, (3 soot particle aerosol mass spectrometer (SP-AMS, (4 on-line high resolution time-of-flight mass spectrometer-thermal desorption aerosol gas chromatograph (HR-ToFMS-TAG, (5 off-line twelve-hour resolution proton nuclear magnetic resonance (H-NMR spectroscopy, and (6 chemical ionization mass spectrometry (CIMS for the analysis of gas-phase precursors of secondary aerosol. Data from each aerosol spectroscopic method were analysed individually following ad-hoc tools (i.e. PMF for AMS, Art-2a for ATOFMS. The results obtained from each techniques are herein presented and compared. This allows us to clearly link the modifications in aerosol chemical composition to transitions in air mass origin and meteorological regimes. Under stagnant conditions, atmospheric stratification at night and early morning hours led to the accumulation of aerosols produced by anthropogenic sources distributed over the Po Valley plain. Such aerosols include primary components such as black

  3. Engineering and Functional Analysis of Mitotic Kinases Through Chemical Genetics.

    Science.gov (United States)

    Jones, Mathew J K; Jallepalli, Prasad V

    2016-01-01

    During mitosis, multiple protein kinases transform the cytoskeleton and chromosomes into new and highly dynamic structures that mediate the faithful transmission of genetic information and cell division. However, the large number and strong conservation of mammalian kinases in general pose significant obstacles to interrogating them with small molecules, due to the difficulty in identifying and validating those which are truly selective. To overcome this problem, a steric complementation strategy has been developed, in which a bulky "gatekeeper" residue within the active site of the kinase of interest is replaced with a smaller amino acid, such as glycine or alanine. The enlarged catalytic pocket can then be targeted in an allele-specific manner with bulky purine analogs. This strategy provides a general framework for dissecting kinase function with high selectivity, rapid kinetics, and reversibility. In this chapter we discuss the principles and techniques needed to implement this chemical genetic approach in mammalian cells.

  4. Chemical weapons detection by fast neutron activation analysis techniques

    Science.gov (United States)

    Bach, P.; Ma, J. L.; Froment, D.; Jaureguy, J. C.

    1993-06-01

    A neutron diagnostic experimental apparatus has been tested for nondestructive verification of sealed munitions. Designed to potentially satisfy a significant number of van-mobile requirements, this equipment is based on an easy to use industrial sealed tube neutron generator that interrogates the munitions of interest with 14 MeV neutrons. Gamma ray spectra are detected with a high purity germanium detector, especially shielded from neutrons and gamma ray background. A mobile shell holder has been used. Possible configurations allow the detection, in continuous or in pulsed modes, of gamma rays from neutron inelastic scattering, from thermal neutron capture, and from fast or thermal neutron activation. Tests on full scale sealed munitions with chemical simulants show that those with chlorine (old generation materials) are detectable in a few minutes, and those including phosphorus (new generation materials) in nearly the same time.

  5. Chemical analysis of 24 dusty (pre-)main-sequence stars

    CERN Document Server

    Acke, B; Acke, Bram; Waelkens, Christoffel

    2004-01-01

    We have analysed the chemical photospheric composition of 24 Herbig Ae/Be and Vega-type stars in search for the lambda Bootis phenomenon. We present the results of the elemental abundances of the sample stars. Some of the stars were never before studied spectroscopically at optical wavelengths. We have determined the projected rotational velocities of our sample stars. Furthermore, we discuss stars that depict a (selective) depletion pattern in detail. HD 4881 and HD 139614 seem to display an overall deficiency. AB Aur and possibly HD 126367 have subsolar values for the iron abundance, but are almost solar in silicon. HD 100546 is the only clear lambda Bootis star in our sample.

  6. Integrated Process Design, Control and Analysis of Intensified Chemical Processes

    DEFF Research Database (Denmark)

    Mansouri, Seyed Soheil

    chemical processes; for example, intensified processes such as reactive distillation. Most importantly, it identifies and eliminates potentially promising design alternatives that may have controllability problems later. To date, a number of methodologies have been proposed and applied on various problems......Process design and process control have been considered as independent problems for many years. In this context, a sequential approach is used where the process is designed first, followed by the control design. However, this sequential approach has its limitations related to dynamic constraint...... violations, for example, infeasible operating points, process overdesign or under-performance. Therefore, by using this approach, a robust performance is not always guaranteed. Furthermore, process design decisions can influence process control and operation. To overcome these limitations, an alternative...

  7. FINITE ELEMENT METHOD AND ANALYSIS FOR CHEMICAL-FLOODING SIMULATION

    Institute of Scientific and Technical Information of China (English)

    YUAN Yirang

    2000-01-01

    This article discusses the enhanced oil recovery numerical simulation of the chemical-flooding (such as surfactants, alcohol, polymers) composed of three-dimensional multicomponent, multiphase and incompressible mixed fluids. The mathematical model can be described as a coupled system of nonlinear partial differential equations with initialboundary value problems. From the actual conditions such as the effect of cross interference and the three-dimensional characteristic of large-scale science-engineering computation, this article puts forward a kind of characteristic finite element fractional step schemes and obtain the optimal order error estimates in L2 norm. Thus we have thoroughly solved the well-known theoretical problem proposed by a famous scientist, R. E. Ewing.

  8. Key study on the potential of hydrazine bisborane for solid- and liquid-state chemical hydrogen storage.

    Science.gov (United States)

    Pylypko, Sergii; Petit, Eddy; Yot, Pascal G; Salles, Fabrice; Cretin, Marc; Miele, Philippe; Demirci, Umit B

    2015-05-04

    Hydrazine bisborane N2H4(BH3)2 (HBB; 16.8 wt %) recently re-emerged as a potential hydrogen storage material. However, such potential is controversial: HBB was seen as a hazardous compound up to 2010, but now it would be suitable for hydrogen storage. In this context, we focused on fundamentals of HBB because they are missing in the literature and should help to shed light on its effective potential while taking into consideration any risk. Experimental/computational methods were used to get a complete characterization data sheet, including, e.g., XRD, NMR, FTIR, Raman, TGA, and DSC. From the reported results and discussion, it is concluded that HBB has potential in the field of chemical hydrogen storage given that both thermolytic and hydrolytic dehydrogenations were analyzed. In solid-state chemical hydrogen storage, it cannot be used in the pristine state (risk of explosion during dehydrogenation) but can be used for the synthesis of derivatives with improved dehydrogenation properties. In liquid-state chemical hydrogen storage, it can be studied for room-temperature dehydrogenation, but this requires the development of an active and selective metal-based catalyst. HBB is a thus a candidate for chemical hydrogen storage.

  9. Linear analysis near a steady-state of biochemical networks: control analysis, correlation metrics and circuit theory

    Directory of Open Access Journals (Sweden)

    Qian Hong

    2008-05-01

    Full Text Available Abstract Background: Several approaches, including metabolic control analysis (MCA, flux balance analysis (FBA, correlation metric construction (CMC, and biochemical circuit theory (BCT, have been developed for the quantitative analysis of complex biochemical networks. Here, we present a comprehensive theory of linear analysis for nonequilibrium steady-state (NESS biochemical reaction networks that unites these disparate approaches in a common mathematical framework and thermodynamic basis. Results: In this theory a number of relationships between key matrices are introduced: the matrix A obtained in the standard, linear-dynamic-stability analysis of the steady-state can be decomposed as A = SRT where R and S are directly related to the elasticity-coefficient matrix for the fluxes and chemical potentials in MCA, respectively; the control-coefficients for the fluxes and chemical potentials can be written in terms of RT BS and ST BS respectively where matrix B is the inverse of A; the matrix S is precisely the stoichiometric matrix in FBA; and the matrix eAt plays a central role in CMC. Conclusion: One key finding that emerges from this analysis is that the well-known summation theorems in MCA take different forms depending on whether metabolic steady-state is maintained by flux injection or concentration clamping. We demonstrate that if rate-limiting steps exist in a biochemical pathway, they are the steps with smallest biochemical conductances and largest flux control-coefficients. We hypothesize that biochemical networks for cellular signaling have a different strategy for minimizing energy waste and being efficient than do biochemical networks for biosynthesis. We also discuss the intimate relationship between MCA and biochemical systems analysis (BSA.

  10. Risk assessment for benefits analysis: framework for analysis of a thyroid-disrupting chemical.

    Science.gov (United States)

    Axelrad, Daniel A; Baetcke, Karl; Dockins, Chris; Griffiths, Charles W; Hill, Richard N; Murphy, Patricia A; Owens, Nicole; Simon, Nathalie B; Teuschler, Linda K

    Benefit-cost analysis is of growing importance in developing policies to reduce exposures to environmental contaminants. To quantify health benefits of reduced exposures, economists generally rely on dose-response relationships estimated by risk assessors. Further, to be useful for benefits analysis, the endpoints that are quantified must be expressed as changes in incidence of illnesses or symptoms that are readily understood by and perceptible to the layperson. For most noncancer health effects and for nonlinear carcinogens, risk assessments generally do not provide the dose-response functions necessary for economic benefits analysis. This article presents the framework for a case study that addresses these issues through a combination of toxicology, epidemiology, statistics, and economics. The case study assesses a chemical that disrupts proper functioning of the thyroid gland, and considers the benefits of reducing exposures in terms of both noncancer health effects (hypothyroidism) and thyroid cancers. The effects are presumed to be due to a mode of action involving interference with thyroid-pituitary functioning that would lead to nonlinear dose response. The framework integrates data from animal testing, statistical modeling, human data from the medical and epidemiological literature, and economic methodologies and valuation studies. This interdisciplinary collaboration differs from the more typical approach in which risk assessments and economic analyses are prepared independently of one another. This framework illustrates particular approaches that may be useful for expanded quantification of adverse health effects, and demonstrates the potential of such interdisciplinary approaches. Detailed implementation of the case study framework will be presented in future publications.

  11. Analysis of Control Power in Controlled Remote State Preparation Schemes

    Science.gov (United States)

    Li, Xihan; Ghose, Shohini

    2017-03-01

    We quantify and analyze the controller's power in controlled remote state preparation schemes. Our analysis provides a lower bound on the control power required for controlled remote preparation of arbitrary D-dimensional states. We evaluate several existing controlled remote state preparation protocols and show that some proposed non-maximally entangled channels are not suitable for perfect controlled remote preparation of arbitrary quantum states from the controller's point of view. We find that for remotely preparing D-dimensional states, the entropy of each controller should be no less than log2 D bits. Our new criteria are not only useful for evaluating controlled remote state preparation schemes but can also be used for other controlled quantum communication schemes.

  12. Integrated separation and optical detection for novel on-chip chemical analysis

    Energy Technology Data Exchange (ETDEWEB)

    Warren, M.E.; Anex, D.S.; Rakestraw, D.; Gourley, P.L.

    1998-03-01

    This report represents the completion of a two years Laboratory Directed Research and Development (LDRD) program to investigate miniaturized systems for chemical detection and analysis. The future of advanced chemical detection and analysis is in miniature devices that are able to characterize increasingly complex samples, a laboratory on a chip. In this concept, chemical operations used to analyze complicated samples in a chemical laboratory sample handling, species separation, chemical derivitization and detection are incorporated into a miniature device. By using electrokinetic flow, this approach does not require pumps or valves, as fluids in microfabricated channels can be driven by externally applied voltages. This is ideal for sample handling in miniature devices. This project was to develop truly miniature on-chip optical systems based on Vertical Cavity Surface Emitting Lasers (VCSELs) and diffractive optics. These can be built into a complete system that also has on-chip electrokinetic fluid handling and chemical separation in a microfabricated column. The primary goal was the design and fabrication of an on-chip separation column with fluorescence sources and detectors that, using electrokinetic flow, can be used as the basis of an automated chemical analysis system. Secondary goals involved investigation of a dispersed fluorescence module that can be used to extend the versatility of the basic system and on chip, intracavity laser absorption as a high sensitivity detection technique.

  13. The composition-explicit distillation curve technique: Relating chemical analysis and physical properties of complex fluids.

    Science.gov (United States)

    Bruno, Thomas J; Ott, Lisa S; Lovestead, Tara M; Huber, Marcia L

    2010-04-16

    The analysis of complex fluids such as crude oils, fuels, vegetable oils and mixed waste streams poses significant challenges arising primarily from the multiplicity of components, the different properties of the components (polarity, polarizability, etc.) and matrix properties. We have recently introduced an analytical strategy that simplifies many of these analyses, and provides the added potential of linking compositional information with physical property information. This aspect can be used to facilitate equation of state development for the complex fluids. In addition to chemical characterization, the approach provides the ability to calculate thermodynamic properties for such complex heterogeneous streams. The technique is based on the advanced distillation curve (ADC) metrology, which separates a complex fluid by distillation into fractions that are sampled, and for which thermodynamically consistent temperatures are measured at atmospheric pressure. The collected sample fractions can be analyzed by any method that is appropriate. The analytical methods we have applied include gas chromatography (with flame ionization, mass spectrometric and sulfur chemiluminescence detection), thin layer chromatography, FTIR, corrosivity analysis, neutron activation analysis and cold neutron prompt gamma activation analysis. By far, the most widely used analytical technique we have used with the ADC is gas chromatography. This has enabled us to study finished fuels (gasoline, diesel fuels, aviation fuels, rocket propellants), crude oils (including a crude oil made from swine manure) and waste oils streams (used automotive and transformer oils). In this special issue of the Journal of Chromatography, specifically dedicated to extraction technologies, we describe the essential features of the advanced distillation curve metrology as an analytical strategy for complex fluids.

  14. Comprehensive Analysis Competence and Innovative Approaches for Sustainable Chemical Production.

    Science.gov (United States)

    Appel, Joerg; Colombo, Corrado; Dtwyler, Urs; Chen, Yun; Kerimoglu, Nimet

    2016-09-01

    Humanity currently sees itself facing enormous economic, ecological, and social challenges. Sustainable products and production in specialty chemistry are an important strategic element to address these megatrends. In addition to that, digitalization and global connectivity will create new opportunities for the industry. One aspect is examined in this paper, which shows the development of comprehensive analysis of production networks for a more sustainable production in which the need for innovative solutions arises. Examples from data analysis, advanced process control and automated performance monitoring are shown. These efforts have significant impact on improved yields, reduced energy and water consumption, and better product performance in the application of the products.

  15. Comprehensive Analysis Competence and Innovative Approaches for Sustainable Chemical Production.

    Science.gov (United States)

    Appel, Joerg; Colombo, Corrado; Dätwyler, Urs; Chen, Yun; Kerimoglu, Nimet

    2016-01-01

    Humanity currently sees itself facing enormous economic, ecological, and social challenges. Sustainable products and production in specialty chemistry are an important strategic element to address these megatrends. In addition to that, digitalization and global connectivity will create new opportunities for the industry. One aspect is examined in this paper, which shows the development of comprehensive analysis of production networks for a more sustainable production in which the need for innovative solutions arises. Examples from data analysis, advanced process control and automated performance monitoring are shown. These efforts have significant impact on improved yields, reduced energy and water consumption, and better product performance in the application of the products.

  16. Electronic Structure, Oxidation State of Sn, and Chemical Stability of Photovoltaic Perovskite Variant Cs2SnI6

    CERN Document Server

    Xiao, Zewen; Zhang, Xiao; Zhou, Yuanyuan; Hosono, Hideo; Kamiya, Toshio

    2015-01-01

    Cs2SnI6, a variant of perovskite CsSnI3, is expected for a photovoltaic material. Based on a simple ionic model, it is expected that Cs2SnI6 is composed of Cs+, I-, and Sn4+ ions and that the band gap is primarily made of occupied I- 5p6 valence band maximum (VBM) and unoccupied Sn4+ 5s conduction band minimum (CBM) similar to SnO2. In this work, we performed density functional theory (DFT) calculations and revealed that the real charge state of the Sn ion in this compound is +2 similar to CsSnI3. This is due to strong covalent nature between the I ion and the Sn ion, the VBM consists of I 5p - I 5p antibonding states, and the CBM of I 5p - Sn 5s antibonding states. The +2 oxidation state of Sn is realized by the apparent charge state of I-2/3, because the I 5p - Sn 5s antibonding states form the unoccupied CBM and apparently 1/18 of the I 5p orbitals are unoccupied. These results are further supported by comparing chemical bonding analyses with those of related compounds. The chemical stability of the Cs2SnI...

  17. Shotgun lipidomic analysis of chemically sulfated sterols compromises analytical sensitivity

    DEFF Research Database (Denmark)

    Casanovas, Albert; Hannibal-Bach, Hans Kristian; Jensen, Ole Nørregaard

    2014-01-01

    Fourier transform mass spectrometry (FTMS) for identification and quantification of lipid species [6]. Shotgun lipidomics affords extensive lipidome coverage by combining the analysis of lipid extracts in positive and negative ion mode [1, 3]. Notably, sterols such as cholesterol and ergosterol exhibit...

  18. Chemical analysis applied to the radiation sterilization of solid ketoprofen

    Science.gov (United States)

    Colak, S.; Maquille, A.; Tilquin, B.

    2006-01-01

    The aim of this work is to investigate the feasibility of radiation sterilization of ketoprofen from a chemical point of view. Although irradiated ketoprofen has already been studied in the literature [Katusin-Razem et al., Radiat. Phys. Chem. 73 111-116 (2005)], new results, on the basis of electron spin resonance (ESR) measurements and the use of hyphenated techniques (GC-MS and LC-MS), are obtained. The ESR spectra of irradiated ketoprofen consists of four unresolved resonance peaks and the mean G-value of ketoprofen is found to be 4 +/- 0.9 nmoles/J, which is very small. HPLC-UV analyses indicate that no significant loss of ketoprofen is detected after irradiation. LC-MS-MS analyses show that the structures of the non-volatile final products are similar to ketoprofen. Benzaldehyde is detected in the irradiated samples after dynamic-extraction GC-MS. The analyses show that ketoprofen is radioresistant and therefore might be radiosterilized.

  19. ISS Potable Water Sampling and Chemical Analysis Results for 2016

    Science.gov (United States)

    Straub, John E., II; Plumlee, Debrah K.; Wallace William T.; Alverson, James T.; Benoit, Mickie J.; Gillispie, Robert L.; Hunter, David; Kuo, Mike; Rutz, Jeffrey A.; Hudson, Edgar K.; Loh, Leslie J.; Gazda, Daniel B.

    2017-01-01

    This paper continues the annual tradition of summarizing at this conference the results of chemical analyses performed on archival potable water samples returned from the International Space Station (ISS). 2016 represented a banner year for life on board the ISS, including the successful conclusion for two crew members of a record one-year mission. Water reclaimed from urine and/or humidity condensate remained the primary source of potable water for the crew members of ISS Expeditions 46-50. The year 2016 was also marked by the end of a long-standing tradition of U.S. sampling and monitoring of Russian Segment potable water sources. Two water samples taken during Expedition 46 in February 2016 and returned on Soyuz 44, represented the final Russian Segment samples to be collected and analyzed by the U.S. side. Although anticipated for 2016, a rise in the total organic carbon (TOC) concentration of the product water from the U.S. water processor assembly due to breakthrough of organic contaminants from the system did not materialize, as evidenced by the onboard TOC analyzer and archive sample results.

  20. Hydrocarbon analysis using desorption atmospheric pressure chemical ionization

    KAUST Repository

    Jjunju, Fred Paul Mark

    2013-07-01

    Characterization of the various petroleum constituents (hydronaphthalenes, thiophenes, alkyl substituted benzenes, pyridines, fluorenes, and polycyclic aromatic hydrocarbons) was achieved under ambient conditions without sample preparation by desorption atmospheric pressure chemical ionization (DAPCI). Conditions were chosen for the DAPCI experiments to control whether ionization was by proton or electron transfer. The protonated molecule [M+H]+ and the hydride abstracted [MH]+ form were observed when using an inert gas, typically nitrogen, to direct a lightly ionized plasma generated by corona discharge onto the sample surface in air. The abundant water cluster ions generated in this experiment react with condensed-phase functionalized hydrocarbon model compounds and their mixtures at or near the sample surface. On the other hand, when naphthalene was doped into the DAPCI gas stream, its radical cation served as a charge exchange reagent, yielding molecular radical cations (M+) of the hydrocarbons. This mode of sample ionization provided mass spectra with better signal/noise ratios and without unwanted side-products. It also extended the applicability of DAPCI to petroleum constituents which could not be analyzed through proton transfer (e.g., higher molecular PAHs such as chrysene). The thermochemistry governing the individual ionization processes is discussed and a desorption/ionization mechanism is inferred. © 2012 Elsevier B.V.

  1. Continuous-flow centrifugation to collect suspended sediment for chemical analysis

    Science.gov (United States)

    Conn, Kathleen E.; Dinicola, Richard S.; Black, Robert W.; Cox, Stephen E.; Sheibley, Richard W.; Foreman, James R.; Senter, Craig A.; Peterson, Norman T.

    2016-12-22

    Recent advances in suspended-sediment monitoring tools and surrogate technologies have greatly improved the ability to quantify suspended-sediment concentrations and to estimate daily, seasonal, and annual suspended-sediment fluxes from rivers to coastal waters. However, little is known about the chemical composition of suspended sediment, and how it may vary spatially between water bodies and temporally within a single system owing to climate, seasonality, land use, and other natural and anthropogenic drivers. Many water-quality contaminants, such as organic and inorganic chemicals, nutrients, and pathogens, preferentially partition in sediment rather than water. Suspended sediment-bound chemical concentrations may be undetected during analysis of unfiltered water samples, owing to small water sample volumes and analytical limitations. Quantification of suspended sediment‑bound chemical concentrations is needed to improve estimates of total chemical concentrations, chemical fluxes, and exposure levels of aquatic organisms and humans in receiving environments. Despite these needs, few studies or monitoring programs measure the chemical composition of suspended sediment, largely owing to the difficulty in consistently obtaining samples of sufficient quality and quantity for laboratory analysis.A field protocol is described here utilizing continuous‑flow centrifugation for the collection of suspended sediment for chemical analysis. The centrifuge used for development of this method is small, lightweight, and portable for the field applications described in this protocol. Project scoping considerations, deployment of equipment and system layout options, and results from various field and laboratory quality control experiments are described. The testing confirmed the applicability of the protocol for the determination of many inorganic and organic chemicals sorbed on suspended sediment, including metals, pesticides, polycyclic aromatic hydrocarbons, and

  2. Biopesticides: State of the Art and Future Opportunities by the American Chemical Society

    Science.gov (United States)

    This chapter from an American Chemical Society symposium reviews areas including how EPA views the benefits of biopesticides, related laws and legal requirements, biopesticide registration, and biopesticide data requirements.

  3. Incorporation of low energy activated nitrogen onto HOPG surface: Chemical states and thermal stability studies by in-situ XPS and Raman spectroscopy

    Science.gov (United States)

    Chandran, Maneesh; Shasha, Michal; Michaelson, Shaul; Hoffman, Alon

    2016-09-01

    In this paper we report the chemical states analysis of activated nitrogen incorporated highly oriented pyrolytic graphite (HOPG) surface under well-controlled conditions. Nitrogen incorporation is carried out by two different processes: an indirect RF nitrogen plasma and low energy (1 keV) N2+ implantation. Bonding configuration, concentration and thermal stability of the incorporated nitrogen species by aforesaid processes are systematically compared by in-situ X-ray photoelectron spectroscopy (XPS). Relatively large concentration of nitrogen is incorporated onto RF nitride HOPG surface (16.2 at.%), compared to N2+ implanted HOPG surface (7.7 at.%). The evolution of N 1s components (N1, N2, N3) with annealing temperature is comprehensively discussed, which indicates that the formation and reorganization of local chemical bonding states are determined by the process of nitridation and not by the prior chemical conditioning (i.e., amorphization or hydrogenation) of the HOPG surface. A combined XPS and Raman spectroscopy studies revealed that N2+ implantation process resulted in a high level of defects to the HOPG surface, which cannot be annealed-out by heat treatment up to 1000 °C. On the other hand, the RF nitrogen plasma process did not produce a high level of surface defects, while incorporating nearly the same amount of stable nitrogen species.

  4. Virus and Bacterial Cell Chemical Analysis by NanoSIMS

    Energy Technology Data Exchange (ETDEWEB)

    Weber, P; Holt, J

    2008-07-28

    In past work for the Department of Homeland Security, the LLNL NanoSIMS team has succeeded in extracting quantitative elemental composition at sub-micron resolution from bacterial spores using nanometer-scale secondary ion mass spectrometry (NanoSIMS). The purpose of this task is to test our NanoSIMS capabilities on viruses and bacterial cells. This initial work has proven successful. We imaged Tobacco Mosaic Virus (TMV) and Bacillus anthracis Sterne cells using scanning electron microscopy (SEM) and then analyzed those samples by NanoSIMS. We were able resolve individual viral particles ({approx}18 nm by 300 nm) in the SEM and extract correlated elemental composition in the NanoSIMS. The phosphorous/carbon ratio observed in TMV is comparable to that seen in bacterial spores (0.033), as was the chlorine/carbon ratio (0.11). TMV elemental composition is consistent from spot to spot, and TMV is readily distinguished from debris by NanoSIMS analysis. Bacterial cells were readily identified in the SEM and relocated in the NanoSIMS for elemental analysis. The Ba Sterne cells were observed to have a measurably lower phosphorous/carbon ratio (0.005), as compared to the spores produced in the same run (0.02). The chlorine/carbon ratio was approximately 2.5X larger in the cells (0.2) versus the spores (0.08), while the fluorine/carbon ratio was approximately 10X lower in the cells (0.008) than the spores (0.08). Silicon/carbon ratios for both cells and spores encompassed a comparable range. The initial data in this study suggest that high resolution analysis is useful because it allows the target agent to be analyzed separate from particulates and other debris. High resolution analysis would also be useful for trace sample analysis. The next step in this work is to determine the potential utility of elemental signatures in these kinds of samples. We recommend bulk analyses of media and agent samples to determine the range of media compositions in use, and to determine how

  5. Reversible Diffusion-Limited Reactions: "Chemical Equilibrium" State and the Law of Mass Action Revisited

    OpenAIRE

    Voituriez, R.; Moreau, M.; Oshanin, G.

    2004-01-01

    The validity of two fundamental concepts of classical chemical kinetics - the notion of "Chemical Equilibrium" and the "Law of Mass Action" - are re-examined for reversible \\textit{diffusion-limited} reactions (DLR), as exemplified here by association/dissociation $A+A \\rightleftharpoons B$ reactions. We consider a general model of long-ranged reactions, such that any pair of $A$ particles, separated by distance $\\mu$, may react with probability $\\omega_+(\\mu)$, and any $B$ may dissociate wit...

  6. State of chemical modeling modules for the degradation of concrete and cements

    Energy Technology Data Exchange (ETDEWEB)

    Meike, A.

    1997-04-15

    This report describes the conceptual framework upon which modeling activities will be needed to predict the chemistry of water in contact with concrete and its degradation products cover a broad area, from developing databases for existing abiotic codes, to developing codes that can simulate the chemical impact of microbial activities at a level of sophistication equivalent to that of the abiotic modeling codes, and ultimately, to simulating drift-scale chemical systems in support of hydrological, geochemical,a nd engineering efforts.

  7. Archaeological and chemical analysis of Tell el Yahudiyeh ware

    Energy Technology Data Exchange (ETDEWEB)

    Kaplan, M F; Harbottle, G; Sayre, E V

    1978-01-01

    Typological and geographic analyses indicate that Tell el Yahudiyeh ware (found in Cyprus, Egypt, Nubia, and the Levant during the Middle Bronze period, c. 1750-1550 B.C.) were probably manufactured in two areas, the Nile Valley and the Levant. Activation analysis was carried out and correlated with the archaeological analyses. Results confirm the two ''families'' of the ware, one Egyptian and one Levantine. Speculations are offered on the social interaction of the period. 11 figures, 2 tables. (DLC)

  8. Dissociative electron transfer in polychlorinated aromatics. Reduction potentials from convolution analysis and quantum chemical calculations.

    Science.gov (United States)

    Romańczyk, Piotr P; Rotko, Grzegorz; Kurek, Stefan S

    2016-08-10

    Formal potentials of the first reduction leading to dechlorination in dimethylformamide were obtained from convolution analysis of voltammetric data and confirmed by quantum chemical calculations for a series of polychlorinated benzenes: hexachlorobenzene (-2.02 V vs. Fc(+)/Fc), pentachloroanisole (-2.14 V), and 2,4-dichlorophenoxy- and 2,4,5-trichlorophenoxyacetic acids (-2.35 V and -2.34 V, respectively). The key parameters required to calculate the reduction potential, electron affinity and/or C-Cl bond dissociation energy, were computed at both DFT-D and CCSD(T)-F12 levels. Comparison of the obtained gas-phase energies and redox potentials with experiment enabled us to verify the relative energetics and the performance of various implicit solvent models. Good agreement with the experiment was achieved for redox potentials computed at the DFT-D level, but only for the stepwise mechanism owing to the error compensation. For the concerted electron transfer/C-Cl bond cleavage process, the application of a high level coupled cluster method is required. Quantum chemical calculations have also demonstrated the significant role of the π*ring and σ*C-Cl orbital mixing. It brings about the stabilisation of the non-planar, C2v-symmetric C6Cl6˙(-) radical anion, explains the experimentally observed low energy barrier and the transfer coefficient close to 0.5 for C6Cl5OCH3 in an electron transfer process followed by immediate C-Cl bond cleavage in solution, and an increase in the probability of dechlorination of di- and trichlorophenoxyacetic acids due to substantial population of the vibrational excited states corresponding to the out-of-plane C-Cl bending at ambient temperatures.

  9. Software for analysis of chemical mixtures--composition, occurrence, distribution, and possible toxicity

    Science.gov (United States)

    Scott, Jonathon C.; Skach, Kenneth A.; Toccalino, Patricia L.

    2013-01-01

    The composition, occurrence, distribution, and possible toxicity of chemical mixtures in the environment are research concerns of the U.S. Geological Survey and others. The presence of specific chemical mixtures may serve as indicators of natural phenomena or human-caused events. Chemical mixtures may also have ecological, industrial, geochemical, or toxicological effects. Chemical-mixture occurrences vary by analyte composition and concentration. Four related computer programs have been developed by the National Water-Quality Assessment Program of the U.S. Geological Survey for research of chemical-mixture compositions, occurrences, distributions, and possible toxicities. The compositions and occurrences are identified for the user-supplied data, and therefore the resultant counts are constrained by the user’s choices for the selection of chemicals, reporting limits for the analytical methods, spatial coverage, and time span for the data supplied. The distribution of chemical mixtures may be spatial, temporal, and (or) related to some other variable, such as chemical usage. Possible toxicities optionally are estimated from user-supplied benchmark data. The software for the analysis of chemical mixtures described in this report is designed to work with chemical-analysis data files retrieved from the U.S. Geological Survey National Water Information System but can also be used with appropriately formatted data from other sources. Installation and usage of the mixture software are documented. This mixture software was designed to function with minimal changes on a variety of computer-operating systems. To obtain the software described herein and other U.S. Geological Survey software, visit http://water.usgs.gov/software/.

  10. The multi-flavor Schwinger model with chemical potential - Overcoming the sign problem with Matrix Product States

    CERN Document Server

    Bañuls, Mari Carmen; Cirac, J Ignacio; Jansen, Karl; Kühn, Stefan; Saito, Hana

    2016-01-01

    During recent years there has been an increasing interest in the application of matrix product states, and more generally tensor networks, to lattice gauge theories. This non-perturbative method is sign problem free and has already been successfully used to compute mass spectra, thermal states and phase diagrams, as well as real-time dynamics for Abelian and non-Abelian gauge models. In previous work we showed the suitability of the method to explore the zero-temperature phase structure of the multi-flavor Schwinger model at non-zero chemical potential, a regime where the conventional Monte Carlo approach suffers from the sign problem. Here we extend our numerical study by looking at the spatially resolved chiral condensate in the massless case. We recover spatial oscillations, similar to the theoretical predictions for the single-flavor case, with a chemical potential dependent frequency and an amplitude approximately given by the homogeneous zero density condensate value.

  11. Excited state properties of the astaxanthin radical cation: A quantum chemical study

    Science.gov (United States)

    Dreuw, Andreas; Starcke, Jan Hendrik; Wachtveitl, Josef

    2010-07-01

    Using time-dependent density functional theory, the excited electronic states of the astaxanthin radical cation (AXT rad + ) are investigated. While the optically allowed excited D 1 and D 3 states are typical ππ∗ excited states, the D 2 and D 4 states are nπ∗ states. Special emphasis is put onto the influence of the carbonyl groups onto the excited states. For this objective, the excited states of four hypothetical carotenoids and zeaxanthin have been computed. Addition of a carbonyl group to a conjugated carbon double bond system does essentially not change the vertical excitation energies of the optically allowed ππ∗ states due to two counter-acting effects: the excitation energy should increase due to the -M-effect of the carbonyl group and at the same time decrease owing to the elongation of the conjugated double bond system by the carbonyl group itself.

  12. Excited state properties of the astaxanthin radical cation: A quantum chemical study

    Energy Technology Data Exchange (ETDEWEB)

    Dreuw, Andreas, E-mail: andreas.dreuw@theochem.uni-frankfurt.de [Institute of Physical and Theoretical Chemistry, Goethe-University Frankfurt, Max von Laue-Str. 7, 60438 Frankfurt am Main (Germany); Starcke, Jan Hendrik; Wachtveitl, Josef [Institute of Physical and Theoretical Chemistry, Goethe-University Frankfurt, Max von Laue-Str. 7, 60438 Frankfurt am Main (Germany)

    2010-07-19

    Using time-dependent density functional theory, the excited electronic states of the astaxanthin radical cation (AXT{sup {center_dot}+}) are investigated. While the optically allowed excited D{sub 1} and D{sub 3} states are typical {pi}{pi}* excited states, the D{sub 2} and D{sub 4} states are n{pi}* states. Special emphasis is put onto the influence of the carbonyl groups onto the excited states. For this objective, the excited states of four hypothetical carotenoids and zeaxanthin have been computed. Addition of a carbonyl group to a conjugated carbon double bond system does essentially not change the vertical excitation energies of the optically allowed {pi}{pi}* states due to two counter-acting effects: the excitation energy should increase due to the -M-effect of the carbonyl group and at the same time decrease owing to the elongation of the conjugated double bond system by the carbonyl group itself.

  13. Inorganic chemical analysis of environmental materials—A lecture series

    Science.gov (United States)

    Crock, J.G.; Lamothe, P.J.

    2011-01-01

    At the request of the faculty of the Colorado School of Mines, Golden, Colorado, the authors prepared and presented a lecture series to the students of a graduate level advanced instrumental analysis class. The slides and text presented in this report are a compilation and condensation of this series of lectures. The purpose of this report is to present the slides and notes and to emphasize the thought processes that should be used by a scientist submitting samples for analyses in order to procure analytical data to answer a research question. First and foremost, the analytical data generated can be no better than the samples submitted. The questions to be answered must first be well defined and the appropriate samples collected from the population that will answer the question. The proper methods of analysis, including proper sample preparation and digestion techniques, must then be applied. Care must be taken to achieve the required limits of detection of the critical analytes to yield detectable analyte concentration (above "action" levels) for the majority of the study's samples and to address what portion of those analytes answer the research question-total or partial concentrations. To guarantee a robust analytical result that answers the research question(s), a well-defined quality assurance and quality control (QA/QC) plan must be employed. This QA/QC plan must include the collection and analysis of field and laboratory blanks, sample duplicates, and matrix-matched standard reference materials (SRMs). The proper SRMs may include in-house materials and/or a selection of widely available commercial materials. A discussion of the preparation and applicability of in-house reference materials is also presented. Only when all these analytical issues are sufficiently addressed can the research questions be answered with known certainty.

  14. Molecular perspectives on solid-state phase transformation and chemical reactivity of drugs: metoclopramide as an example.

    Science.gov (United States)

    Lin, Shan-Yang

    2015-02-01

    Here, I provide an overview of the solid-state characteristics, phase transformations and chemical reactions of metoclopramide hydrochloride monohydrate (MCP HCl H2O). Three unique techniques, including thermoanalytical methods, one-step simultaneous differential scanning calorimetry (DSC) and Fourier transform infrared (FTIR) microspectroscopy, and hot-stage microscopic (HSM) imaging, have been applied to study the solid-state phase transitions of MCP HCl H2O in continuous dehydration, amorphization and recrystallization processes. I also review the effects of grinding or heating on ion-exchange reactions, milling, compression or colyophilization on Maillard reactions, and γ-ray irradiation or electron beams on radiolysis in the solid state. I also report the exposure of MCP HCl H2O in solution to light, irradiation, oxidants or π-acceptors. This review will serve as a useful keynote for the evolving realm of solid-state chemistry research.

  15. Prediction of the Chapman–Jouguet chemical equilibrium state in a detonation wave from first principles based reactive molecular dynamics

    OpenAIRE

    Guo, Dezhou; Zybin, Sergey V.; An, Qi; Goddard, William A.; Huang, Fenglei

    2016-01-01

    The combustion or detonation of reacting materials at high temperature and pressure can be characterized by the Chapman–Jouguet (CJ) state that describes the chemical equilibrium of the products at the end of the reaction zone of the detonation wave for sustained detonation. This provides the critical properties and product kinetics for input to macroscale continuum simulations of energetic materials. We propose the ReaxFF Reactive Dynamics to CJ point protocol (Rx2CJ) for predicting the CJ s...

  16. Mapping the chemical states of an element inside a sample using tomographic x-ray absorption spectroscopy.

    Energy Technology Data Exchange (ETDEWEB)

    Schroer, C G; Kuhlmann, M; Gunzler, T F; Lengeler, B; Richwin, M; Griesebock, B; Lutzenkirchen-Hect, D; Frahm, R; Ziegler, E; Mashayekhi, A; Haeffner, D R; Grunwaldt, J -D; Baiker, A; XFD,

    2003-05-12

    Hard x-ray absorption spectroscopy is combined with scanning microtomography to reconstruct full near-edge spectra of an elemental species at each location on an arbitrary virtual section through a sample. These spectra reveal the local concentrations of different chemical compounds of the absorbing element inside the sample and give insight into the oxidation state, the local atomic structure, and the local projected free density of states. The method is implemented by combining a quick scanning monochromator and data acquisition system with a scanning microprobe setup based on refractive x-ray lenses.

  17. Chemical landscape analysis with the OpenTox framework.

    Science.gov (United States)

    Jeliazkova, Nina; Jeliazkov, Vedrin

    2012-01-01

    , the method is implemented as part of an existing open source Ambit package and could be accessed via an OpenTox API compliant web service and via an interactive application, running within a modern, JavaScript enabled web browser. Combined with the functionalities already offered by the OpenTox framework, like data sharing and remote calculations, it could be a useful tool for exploring chemical landscapes online.

  18. Nanoelectromechanical Resonator Arrays for Ultrafast, Gas-Phase Chromatographic Chemical Analysis

    OpenAIRE

    Li, Mo; Myers, E. B.; Tang, H. X.; Aldridge, S. J.; McCaig, H. C.; Whiting, J. J.; Simonson, R. J.; Lewis, N. S.; Roukes, M. L.

    2010-01-01

    Miniaturized gas chromatography (GC) systems can provide fast, quantitative analysis of chemical vapors in an ultrasmall package. We describe a chemical sensor technology based on resonant nanoelectromechanical systems (NEMS) mass detectors that provides the speed, sensitivity, specificity, and size required by the microscale GC paradigm. Such NEMS sensors have demonstrated detection of subparts per billion (ppb) concentrations of a phosphonate analyte. By combining two channels of NEMS detec...

  19. Theoretical considerations of Flow Injection Analysis in the Absence of Chemical Reactions

    DEFF Research Database (Denmark)

    Andersen, Jens Enevold Thaulov

    2000-01-01

    The fundamental mechanism of flow injection analysis (FIA) is assumed to be simple dissusion and the response of the detector is included in a model description that provide information about the shape of the FIA peak in terms of, basically, five parameters. Two of the five parameters are associa...... that any deviation from the features of the present model and the results of a tentative chemical reaction with one of the test compounds, is related to chemical kinetics....

  20. Techniques for SMM/THz Chemical Analysis: Investigations and Exploitation of the Large Molecule Limit

    Science.gov (United States)

    2014-03-03

    SECURITY CLASSIFICATION OF: It has long been recognized that the SMM /THz has a unique combinations of attributes that make it attractive as a basis for...applicability of SMM chemical sensors; the second is to explore infrared – SMM double resonance as a basis for atmospheric remote sensing; and the third...2014 12-Aug-2009 11-Aug-2013 Approved for Public Release; Distribution Unlimited Techniques for SMM /THz Chemical Analysis: Investigations and

  1. Reachability for Finite-State Process Algebras Using Static Analysis

    DEFF Research Database (Denmark)

    Skrypnyuk, Nataliya; Nielson, Flemming

    2011-01-01

    In this work we present an algorithm for solving the reachability problem in finite systems that are modelled with process algebras. Our method uses Static Analysis, in particular, Data Flow Analysis, of the syntax of a process algebraic system with multi-way synchronisation. The results...... of the Data Flow Analysis are used in order to “cut off” some of the branches in the reachability analysis that are not important for determining, whether or not a state is reachable. In this way, it is possible for our reachability algorithm to avoid building large parts of the system altogether and still...

  2. Current state and temporal evolution of the chemical composition of atmospheric depositions in forest areas of the CONECOFOR network

    Directory of Open Access Journals (Sweden)

    Marchetto A

    2014-04-01

    Full Text Available Current state and temporal evolution of the chemical composition of atmospheric depositions in forest areas of the CONECOFOR network. Since 1997, atmospheric deposition was sampled and analyzed in the permanent plots of the Italian network for the evaluation of forest health (CONECOFOR, under the coordination of the Italian Forest Service. This paper presents the results of the activity carried out in 2009, when the EU-funded LIFE+ “FutMon” project allowed to extend the sampling network to 22 sites. Long-term trends will also be evaluated for the sampling sites with the longest time series. The sampling of open field bulk deposition was performed in a clearance close to the CONECOFOR permanent plots, while throughfall deposition and stemflow (in beech stand, only were sampled in the plot. Deposition samples were collected weekly and sent to the laboratories, where they were analyzed for pH, conductivity, major ions, and total carbon and nitrogen. Most measured variables showed a strong geographical gradient. For example, nitrogen deposition was relatively high in the Po plain (where the emissions of nitrogen oxides and ammonia are the highest and surrounding hills, reaching 10-20 kgN ha-1 y-1 in the open field and 13-25 kgN ha-1 y-1 in the throughfall. Sulphate deposition also showed a marked geographical gradient. Deposition of marine aerosol also had an important impact on the chemical composition of atmospheric deposition in Italy, together with the episodic deposition of Saharan dust, which showed a marked gradient, with highest values in the southernmost plots. Trend analysis was carried out on 10 sites running since the beginning of the program. A general negative trend in sulphate concentration was detected, paralleled in most plots by a positive trend in deposition pH, in good agreement with the strong reduction in the emission of sulphur dioxide recorded in the last decades. Nitrogen concentration also showed a significant decrease

  3. Sustainability in the Design, Synthesis and Analysis of Chemical Engineering Processes 1st edition (Preface)

    Science.gov (United States)

    This book preface explains the needs found by the book editors for assembling the state of the art of technical and scientific knowledge relevant to chemical engineering, sustainability, and sustainable uses of wastes and materials management, and to do so in an accessible and c...

  4. The dilemma in prioritizing chemicals for environmental analysis: known versus unknown hazards.

    Science.gov (United States)

    Anna, Sobek; Sofia, Bejgarn; Christina, Rudén; Magnus, Breitholtz

    2016-08-10

    A major challenge for society is to manage the risks posed by the many chemicals continuously emitted to the environment. All chemicals in production and use cannot be monitored and science-based strategies for prioritization are essential. In this study we review available data to investigate which substances are included in environmental monitoring programs and published research studies reporting analyses of chemicals in Baltic Sea fish between 2000 and 2012. Our aim is to contribute to the discussion of priority settings in environmental chemical monitoring and research, which is closely linked to chemical management. In total, 105 different substances or substance groups were analyzed in Baltic Sea fish. Polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans (PCDD/Fs) and polychlorinated biphenyls (PCBs) were the most studied substances or substance groups. The majority, 87%, of all analyses comprised 20% of the substances or substance groups, whereas 46 substance groups (44%) were analyzed only once. Almost three quarters of all analyses regarded a POP-substance (persistent organic pollutant). These results demonstrate that the majority of analyses on environmental contaminants in Baltic Sea fish concern a small number of already regulated chemicals. Legacy pollutants such as POPs pose a high risk to the Baltic Sea due to their hazardous properties. Yet, there may be a risk that prioritizations for chemical analyses are biased based on the knowns of the past. Such biases may lead to society failing in identifying risks posed by yet unknown hazardous chemicals. Alternative and complementary ways to identify priority chemicals are needed. More transparent communication between risk assessments performed as part of the risk assessment process within REACH and monitoring programs, and information on chemicals contained in consumer articles, would offer ways to identify chemicals for environmental analysis.

  5. State machine analysis of sensor data from dynamic processes

    Energy Technology Data Exchange (ETDEWEB)

    Cook, William R.; Brabson, John M.; Deland, Sharon M.

    2003-12-23

    A state machine model analyzes sensor data from dynamic processes at a facility to identify the actual processes that were performed at the facility during a period of interest for the purpose of remote facility inspection. An inspector can further input the expected operations into the state machine model and compare the expected, or declared, processes to the actual processes to identify undeclared processes at the facility. The state machine analysis enables the generation of knowledge about the state of the facility at all levels, from location of physical objects to complex operational concepts. Therefore, the state machine method and apparatus may benefit any agency or business with sensored facilities that stores or manipulates expensive, dangerous, or controlled materials or information.

  6. Numerical analysis of decoy state quantum key distribution protocols

    Energy Technology Data Exchange (ETDEWEB)

    Harrington, Jim W [Los Alamos National Laboratory; Rice, Patrick R [Los Alamos National Laboratory

    2008-01-01

    Decoy state protocols are a useful tool for many quantum key distribution systems implemented with weak coherent pulses, allowing significantly better secret bit rates and longer maximum distances. In this paper we present a method to numerically find optimal three-level protocols, and we examine how the secret bit rate and the optimized parameters are dependent on various system properties, such as session length, transmission loss, and visibility. Additionally, we show how to modify the decoy state analysis to handle partially distinguishable decoy states as well as uncertainty in the prepared intensities.

  7. The challenge of predicting problematic chemicals using a decision analysis tool: Triclosan as a case study.

    Science.gov (United States)

    Perez, Angela L; Gauthier, Alison M; Ferracini, Tyler; Cowan, Dallas M; Kingsbury, Tony; Panko, Julie

    2017-01-01

    Manufacturers lack a reliable means for determining whether a chemical will be targeted for deselection from their supply chain. In this analysis, 3 methods for determining whether a specific chemical (triclosan) would meet the criteria necessary for being targeted for deselection are presented. The methods included a list-based approach, use of a commercially available chemical assessment software tool run in 2 modes, and a public interest evaluation. Our results indicated that triclosan was included on only 6 of the lists reviewed, none of which were particularly influential in chemical selection decisions. The results from the chemical assessment tool evaluations indicated that human and ecological toxicity for triclosan is low and received scores indicating that the chemical would be considered of low concern. However, triclosan's peak public interest tracked several years in advance of increased regulatory scrutiny of this chemical suggesting that public pressure may have been influential in deselection decisions. Key data gaps and toxicity endpoints not yet regulated such as endocrine disruption potential or phototoxicity, but that are important to estimate the trajectory for deselection of a chemical, are discussed. Integr Environ Assess Manag 2017;13:198-207. © 2016 SETAC.

  8. Chemical food safety issues in the United States: past, present, and future.

    Science.gov (United States)

    Jackson, Lauren S

    2009-09-23

    Considerable advances have been made over the past century in the understanding of the chemical hazards in food and ways for assessing and managing these risks. At the turn of the 20th century, many Americans were exposed to foods adulterated with toxic compounds. In the 1920s the increasing use of insecticides led to concerns of chronic ingestion of heavy metals such as lead and arsenic from residues remaining on crops. By the 1930s, a variety of agrochemicals were commonly used, and food additives were becoming common in processed foods. During the 1940s and 1950s advances were made in toxicology, and more systematic approaches were adopted for evaluating the safety of chemical contaminants in food. Modern gas chromatography and liquid chromatography, both invented in the 1950s and 1960s, were responsible for progress in detecting, quantifying, and assessing the risk of food contaminants and adulterants. In recent decades, chemical food safety issues that have been the center of media attention include the presence of natural toxins, processing-produced toxins (e.g., acrylamide, heterocyclic aromatic amines, and furan), food allergens, heavy metals (e.g., lead, arsenic, mercury, cadmium), industrial chemicals (e.g., benzene, perchlorate), contaminants from packaging materials, and unconventional contaminants (melamine) in food and feed. Due to the global nature of the food supply and advances in analytical capabilities, chemical contaminants will continue to be an area of concern for regulatory agencies, the food industry, and consumers in the future.

  9. Dynamic thermal analysis of machines in running state

    CERN Document Server

    Wang, Lihui

    2014-01-01

    With the increasing complexity and dynamism in today’s machine design and development, more precise, robust and practical approaches and systems are needed to support machine design. Existing design methods treat the targeted machine as stationery. Analysis and simulation are mostly performed at the component level. Although there are some computer-aided engineering tools capable of motion analysis and vibration simulation etc., the machine itself is in the dry-run state. For effective machine design, understanding its thermal behaviours is crucial in achieving the desired performance in real situation. Dynamic Thermal Analysis of Machines in Running State presents a set of innovative solutions to dynamic thermal analysis of machines when they are put under actual working conditions. The objective is to better understand the thermal behaviours of a machine in real situation while at the design stage. The book has two major sections, with the first section presenting a broad-based review of the key areas of ...

  10. Environmental Chemical Analysis (by B. B. Kebbekus and S. Mitra)

    Science.gov (United States)

    Bower, Reviewed By Nathan W.

    1999-11-01

    This text helps to fill a void in the market, as there are relatively few undergraduate instrumental analysis texts designed specifically for the expanding population of environmental science students. R. N. Reeve's introductory, open-learning Environmental Analysis (Wiley, 1994) is one of the few, and it is aimed at a lower level and is less appropriate for traditional classroom study. Kebbekus and Mitra's book appears to be an update of I. Marr and M. Cresser's excellent 1983 text by the same name (and also published under the Chapman and Hall imprint). It assumes no background in instrumental methods of analysis but it does depend upon a good general chemistry background in kinetic and equilibrium calculations and the standard laboratory techniques found in a classical introduction to analytical chemistry. The slant taken by the authors is aimed more toward engineers, not only in the choice of topics, but also in how they are presented. For example, the statistical significance tests presented follow an engineering format rather than the standard used in analytical chemistry. This approach does not detract from the book's clarity. The writing style is concise and the book is generally well written. The earlier text, which has become somewhat of a classic, took the unusual step of teaching the instruments in the context of their environmental application. It was divided into sections on the "atmosphere", the "hydrosphere", the "lithosphere", and the "biosphere". This text takes a similar approach in the second half, with chapters on methods for air, water, and solid samples. Users who intend to use the book as a text instead of a reference will appreciate the addition of chapters in the first half of the book on spectroscopic, chromatographic, and mass spectrometric methods. The six chapters in these two parts of the book along with four chapters scattered throughout on environmental measurements, sampling, sample preparation, and quality assurance make a nice

  11. Surface characterization and chemical analysis of bamboo substrates pretreated by alkali hydrogen peroxide.

    Science.gov (United States)

    Song, Xueping; Jiang, Yan; Rong, Xianjian; Wei, Wei; Wang, Shuangfei; Nie, Shuangxi

    2016-09-01

    The surface characterization and chemical analysis of bamboo substrates by alkali hydrogen peroxide pretreatment (AHPP) were investigated in this study. The results tended to manifest that AHPP prior to enzymatic and chemical treatment was potential for improving accessibility and reactivity of bamboo substrates. The inorganic components, organic solvent extractives and acid-soluble lignin were effectively removed by AHPP. X-ray photoelectron spectroscopy (XPS) analysis indicated that the surface of bamboo chips had less lignin but more carbohydrate after pre-treatment. Fiber surfaces became etched and collapsed, and more pores and debris on the substrate surface were observed with Scanning Electron Microscopy (SEM). Brenauer-Emmett-Teller (BET) results showed that both of pore volume and surface area were increased after AHPP. Although XRD analysis showed that AHPP led to relatively higher crystallinity, pre-extraction could overall enhance the accessibility of enzymes and chemicals into the bamboo structure.

  12. Analysis of current state and prospects of steel production development

    Science.gov (United States)

    Protopopov, E. V.; Feyler, S. V.

    2016-09-01

    Data on world production of steel in the XXI century are provided. Analysis of current state and prospects of ferrous metallurgy development in the Russian Federation is carried out. Results of national steel production performance during 10 months of the year 2015 are given for different countries. Analysis of the main directions of metallurgical equipment import substitution aimed at technological independence in the industry is made. Russian ferrous metallurgy development predictions in its’ main directions up to 2030 is provided.

  13. Analysis of Member State RED implementation. Final Report (Task 2)

    Energy Technology Data Exchange (ETDEWEB)

    Peters, D.; Alberici, S.; Toop, G. [Ecofys, Utrecht (Netherlands); Kretschmer, B. [Institute for European Environmental Policy IEEP, London (United Kingdom)

    2012-12-15

    This report describes the way EU Member States have transposed the sustainability and chain of custody requirements for biofuels as laid down in the Renewable Energy Directive (RED) and Fuel Quality Directive (FQD). In the assessment of Member States' implementation, the report mainly focuses on effectiveness and administrative burden. Have Member States transposed the Directives in such a way that compliance with the sustainability criteria can be ensured as effectively as possible? To what extent does the Member States' implementation lead to unnecessary administrative burden for economic operators in the (bio)fuel supply chain? The report focuses specifically on the transposition of the sustainability and chain of custody requirements, not on the target for renewables on transport. This means that for example the double counting provision is not included as part of the scope of this report. This report starts with an introduction covering the implementation of the Renewable Energy (and Fuel Quality) Directive into national legislation, the methodology by which Member States were assessed against effectiveness and administrative burden and the categorisation of Member State's national systems for RED-implementation (Chapter 1). The report continues with a high level description of each Member State system assessed (Chapter 2). Following this, the report includes analysis of the Member States on the effectiveness and administrative burden of a number of key ('major') measures (Chapter 3). The final chapter presents the conclusions and recommendations (Chapter 4)

  14. Chemical and Nutrient Analysis of Gingerbread Plum (Neocarya macrophylla Seeds

    Directory of Open Access Journals (Sweden)

    Tidjani Amza

    2010-07-01

    Full Text Available The proximate composition of gingerbread plum (Neocarya macrophylla seeds, mineral, fatty acid and amino acid compositions were evaluated. The proximate analysis revealed the following composition: moisture 10.57 and 10%, ash 4.43 and 6.43%, fat 47.28 and 2.14%, crude protein 20.37 and 61.71%, carbohydrates 8.64 and 12.10% and crude fiber 8.70 and 7.37% for Gingerbread Plum Seed Flour (GPSF and Defatted Gingerbread Plum Seed Flour (DGPSF respectively. Oleic, linoleic and arachidonic acids were the major unsaturated fatty acids with 47.15, 19.10 and 17.64% respectively. Saturated fatty acids accounted for 14.72% of total fatty acids. The main saturated fatty acids were palmitic and stearic, with minute amounts of arachidic. Magnesium, potassium and calcium were the predominant elements present in the seeds. Copper, iron and manganese were also detected in appreciable amounts. Essential amino acids were above the recommended amount by Food Agricultural Organization/W orld Health Organization (FAO/WHO for humans. The results of the present investigation showed that gingerbread plum seeds are a rich source of many important nutrients that appear to have a very positive effect on human health.

  15. Chemical analysis of Asymptotic Giant Branch stars in M62

    CERN Document Server

    Lapenna, E; Ferraro, F R; Origlia, L; Lanzoni, B; Massari, D; Dalessandro, E

    2015-01-01

    We have collected UVES-FLAMES high-resolution spectra for a sample of 6 asymptotic giant branch (AGB) and 13 red giant branch (RGB) stars in the Galactic globular cluster M62 (NGC6266). Here we present the detailed abundance analysis of iron, titanium, and light-elements (O, Na, Al and Mg). For the majority (5 out 6) of the AGB targets we find that the abundances, of both iron and titanium, determined from neutral lines are significantly underestimated with respect to those obtained from ionized features, the latter being, instead, in agreement with those measured for the RGB targets. This is similar to recent findings in other clusters and may suggest the presence of Non-Local Thermodynamical Equilibrium (NLTE) effects. In the O-Na, Al-Mg and Na-Al planes, the RGB stars show the typical correlations observed for globular cluster stars. Instead, all the AGB targets are clumped in the regions where first generation stars are expected to lie, similarly to what recently found for the AGB population of NGC6752. W...

  16. A regional assessment of chemicals of concern in surface waters of four Midwestern United States national parks.

    Science.gov (United States)

    Elliott, Sarah M; VanderMeulen, David D

    2017-02-01

    Anthropogenic chemicals and their potential for adverse biological effects raise concern for aquatic ecosystem health in protected areas. During 2013-15, surface waters of four Midwestern United States national parks were sampled and analyzed for wastewater indicators, pharmaceuticals, personal care products, and pesticides. More chemicals and higher concentrations were detected at the two parks with greater urban influences (Mississippi National River and Recreation Area and Indiana Dunes National Lakeshore) than at the two more remote parks (Apostle Islands National Lakeshore and Isle Royale National Park). Atrazine (10-15ng/L) and N,N-diethyl-meta-toluamide (16-120ng/L) were the only chemicals detected in inland lakes of a remote island national park (Isle Royale National Park). Bisphenol A and organophosphate flame retardants were commonly detected at the other sampled parks. Gabapentin and simazine had the highest observed concentrations (>1000ng/L) in three and two samples, respectively. At the two parks with urban influences, metolachlor and simazine concentrations were similar to those reported for other major urban rivers in the United States. Environmental concentrations of detected chemicals were often orders of magnitude less than standards or reference values with three exceptions: (1) hydrochlorothiazide exceeded a human health-based screening value in seven samples, (2) estrone exceeded a predicted critical environmental concentration for fish pharmacological effects in one sample, and (3) simazine was approaching the 4000ng/L Maximum Contaminant Level in one sample even though this concentration is not expected to reflect peak pesticide use. Although few environmental concentrations were approaching or exceeded standards or reference values, concentrations were often in ranges reported to elicit effects in aquatic biota. Data from this study will assist in establishing a baseline for chemicals of concern in Midwestern national parks and highlight

  17. A regional assessment of chemicals of concern in surface waters of four Midwestern United States national parks

    Science.gov (United States)

    Elliott, Sarah M.; VanderMeulen, David

    2017-01-01

    Anthropogenic chemicals and their potential for adverse biological effects raise concern for aquatic ecosystem health in protected areas. During 2013–15, surface waters of four Midwestern United States national parks were sampled and analyzed for wastewater indicators, pharmaceuticals, personal care products, and pesticides. More chemicals and higher concentrations were detected at the two parks with greater urban influences (Mississippi National River and Recreation Area and Indiana Dunes National Lakeshore) than at the two more remote parks (Apostle Islands National Lakeshore and Isle Royale National Park). Atrazine (10–15 ng/L) and N,N-diethyl-meta-toluamide (16–120 ng/L) were the only chemicals detected in inland lakes of a remote island national park (Isle Royale National Park). Bisphenol A and organophosphate flame retardants were commonly detected at the other sampled parks. Gabapentin and simazine had the highest observed concentrations (> 1000 ng/L) in three and two samples, respectively. At the two parks with urban influences, metolachlor and simazine concentrations were similar to those reported for other major urban rivers in the United States. Environmental concentrations of detected chemicals were often orders of magnitude less than standards or reference values with three exceptions: (1) hydrochlorothiazide exceeded a human health-based screening value in seven samples, (2) estrone exceeded a predicted critical environmental concentration for fish pharmacological effects in one sample, and (3) simazine was approaching the 4000 ng/L Maximum Contaminant Level in one sample even though this concentration is not expected to reflect peak pesticide use. Although few environmental concentrations were approaching or exceeded standards or reference values, concentrations were often in ranges reported to elicit effects in aquatic biota. Data from this study will assist in establishing a baseline for chemicals of concern in Midwestern national parks and

  18. Chimera and chimera-like states in populations of nonlocally coupled homogeneous and heterogeneous chemical oscillators

    Science.gov (United States)

    Nkomo, Simbarashe; Tinsley, Mark R.; Showalter, Kenneth

    2016-09-01

    Chimera and chimera-like states are characterized in populations of photochemically coupled Belousov-Zhabotinsky (BZ) oscillators. Simple chimeras and chimera states with multiple and traveling phase clusters, phase-slip behavior, and chimera-like states with phase waves are described. Simulations with a realistic model of the discrete BZ system of populations of homogeneous and heterogeneous oscillators are compared with each other and with experimental behavior.

  19. Analysis of the State of Steam Generator Tubes

    Energy Technology Data Exchange (ETDEWEB)

    Bergunker, Olga [JSC OKB ' Gidropress' , 142103 Podolsk (Russian Federation)

    2008-07-01

    The problem of safe operation of SG heat exchanging tubes, of both economical and effective control of their state is still important these days. Issues connected with peculiarities of methods of SG tubes inspection, automated analysis of the inspection results, tubes state analysis and development of algorithms of forecasting their state are considered in this report. The need for effective use of extensive data arrays on SG operation has led to the necessity of creating software tools for collection, storage and analysis of these data. The data-analytical system 'NPP Steam Generators' meant for data systematization and visualization as well as various types of analyses of data on eddy current inspection of WWER-440 and WWER-1000 SG tubes is presented in this report. The main possibilities of the data-analytical system (DAS), the code current state and prospects of its development are shown. The main fields of DAS application are considered and some results of its practical use are mentioned, namely, in the field of forecasting SG tubes state. (authors)

  20. Chemical Analysis of a "Miller-Type" Complex Prebiotic Broth: Part I: Chemical Diversity, Oxygen and Nitrogen Based Polymers.

    Science.gov (United States)

    Wollrab, Eva; Scherer, Sabrina; Aubriet, Frédéric; Carré, Vincent; Carlomagno, Teresa; Codutti, Luca; Ott, Albrecht

    2016-06-01

    In a famous experiment Stanley Miller showed that a large number of organic substances can emerge from sparking a mixture of methane, ammonia and hydrogen in the presence of water (Miller, Science 117:528-529, 1953). Among these substances Miller identified different amino acids, and he concluded that prebiotic events may well have produced many of Life's molecular building blocks. There have been many variants of the original experiment since, including different gas mixtures (Miller, J Am Chem Soc 77:2351-2361, 1955; Oró Nature 197:862-867, 1963; Schlesinger and Miller, J Mol Evol 19:376-382, 1983; Miyakawa et al., Proc Natl Acad Sci 99:14,628-14,631, 2002). Recently some of Miller's remaining original samples were analyzed with modern equipment (Johnson et al. Science 322:404-404, 2008; Parker et al. Proc Natl Acad Sci 108:5526-5531, 2011) and a total of 23 racemic amino acids were identified. To give an overview of the chemical variety of a possible prebiotic broth, here we analyze a "Miller type" experiment using state of the art mass spectrometry and NMR spectroscopy. We identify substances of a wide range of saturation, which can be hydrophilic, hydrophobic or amphiphilic in nature. Often the molecules contain heteroatoms, with amines and amides being prominent classes of molecule. In some samples we detect ethylene glycol based polymers. Their formation in water requires the presence of a catalyst. Contrary to expectations, we cannot identify any preferred reaction product. The capacity to spontaneously produce this extremely high degree of molecular variety in a very simple experiment is a remarkable feature of organic chemistry and possibly prerequisite for Life to emerge. It remains a future task to uncover how dedicated, organized chemical reaction pathways may have arisen from this degree of complexity.

  1. Chemical Analysis of a "Miller-Type" Complex Prebiotic Broth. Part I: Chemical Diversity, Oxygen and Nitrogen Based Polymers

    Science.gov (United States)

    Wollrab, Eva; Scherer, Sabrina; Aubriet, Frédéric; Carré, Vincent; Carlomagno, Teresa; Codutti, Luca; Ott, Albrecht

    2016-06-01

    In a famous experiment Stanley Miller showed that a large number of organic substances can emerge from sparking a mixture of methane, ammonia and hydrogen in the presence of water (Miller, Science 117:528-529, 1953). Among these substances Miller identified different amino acids, and he concluded that prebiotic events may well have produced many of Life's molecular building blocks. There have been many variants of the original experiment since, including different gas mixtures (Miller, J Am Chem Soc 77:2351-2361, 1955; Oró Nature 197:862-867, 1963; Schlesinger and Miller, J Mol Evol 19:376-382, 1983; Miyakawa et al., Proc Natl Acad Sci 99:14,628-14,631, 2002). Recently some of Miller's remaining original samples were analyzed with modern equipment (Johnson et al. Science 322:404-404, 2008; Parker et al. Proc Natl Acad Sci 108:5526-5531, 2011) and a total of 23 racemic amino acids were identified. To give an overview of the chemical variety of a possible prebiotic broth, here we analyze a "Miller type" experiment using state of the art mass spectrometry and NMR spectroscopy. We identify substances of a wide range of saturation, which can be hydrophilic, hydrophobic or amphiphilic in nature. Often the molecules contain heteroatoms, with amines and amides being prominent classes of molecule. In some samples we detect ethylene glycol based polymers. Their formation in water requires the presence of a catalyst. Contrary to expectations, we cannot identify any preferred reaction product. The capacity to spontaneously produce this extremely high degree of molecular variety in a very simple experiment is a remarkable feature of organic chemistry and possibly prerequisite for Life to emerge. It remains a future task to uncover how dedicated, organized chemical reaction pathways may have arisen from this degree of complexity.

  2. CHEMICAL ANALYSIS OF ASYMPTOTIC GIANT BRANCH STARS IN M62

    Energy Technology Data Exchange (ETDEWEB)

    Lapenna, E.; Mucciarelli, A.; Ferraro, F. R.; Lanzoni, B.; Dalessandro, E. [Dipartimento di Fisica e Astronomia, Università degli Studi di Bologna, Viale Berti Pichat 6/2, I-40127 Bologna (Italy); Origlia, L.; Massari, D. [INAF-Osservatorio Astronomico di Bologna, Via Ranzani, 1, I-40127 Bologna (Italy)

    2015-11-10

    We have collected UVES-FLAMES high-resolution spectra for a sample of 6 asymptotic giant branch (AGB) and 13 red giant branch (RGB) stars in the Galactic globular cluster (GC) M62 (NGC 6266). Here we present the detailed abundance analysis of iron, titanium, and light elements (O, Na, Mg, and Al). For the majority (five out of six) of the AGB targets, we find that the abundances of both iron and titanium determined from neutral lines are significantly underestimated with respect to those obtained from ionized features, the latter being, instead, in agreement with those measured for the RGB targets. This is similar to recent findings in other clusters and may suggest the presence of nonlocal thermodynamic equilibrium (NLTE) effects. In the O–Na, Al–Mg, and Na–Al planes, the RGB stars show the typical correlations observed for GC stars. Instead, all the AGB targets are clumped in the regions where first-generation stars are expected to lie, similar to what was recently found for the AGB population of NGC 6752. While the sodium and aluminum abundances could be underestimated as a consequence of the NLTE bias affecting iron and titanium, the oxygen line used does not suffer from the same effects, and the lack of O-poor AGB stars therefore is a solid result. We can thus conclude that none of the investigated AGB stars belongs to the second stellar generation of M62. We also find an RGB star with extremely high sodium abundance ([Na/Fe] = +1.08 dex)

  3. Chemical Reactors.

    Science.gov (United States)

    Kenney, C. N.

    1980-01-01

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

  4. Solid-state nanoparticle coated emulsions for encapsulation and improving the chemical stability of all-trans-retinol.

    Science.gov (United States)

    Ghouchi-Eskandar, Nasrin; Simovic, Spomenka; Prestidge, Clive A

    2012-02-28

    Submicron oil-in-water (o/w) emulsions stabilised with conventional surfactants and silica nanoparticles were prepared and freeze-dried to obtain free-flowing powders with good redispersibility and a three-dimensional porous matrix structure. Solid-state emulsions were characterised for visual appearance, particle size distribution, zeta potential and reconstitution properties after freeze-drying with various sugars and at a range of sugar to oil ratios. Comparative degradation kinetics of all-trans-retinol from freeze-dried and liquid emulsions was investigated as a function of storage temperatures. Optimum stability was observed for silica-coated oleylamine emulsions at 4 °C in their wet state. The half-life of all-trans-retinol was 25.66 and 22.08 weeks for silica incorporation from the oil and water phases respectively. This was ∼4 times higher compared to the equivalent solid-state emulsions with drug half-life of 6.18 and 6.06 weeks at 4 °C. Exceptionally, at a storage temperature of 40 °C, the chemical stability of the drug was 3 times higher in the solid-state compared to the wet emulsions which confirmed that freeze-drying is a promising approach to improve the chemical stability of water-labile compounds provided that the storage conditions are optimised.

  5. Participation in the 1999 IAEA interlaboratory comparison on chemical analysis of groundwater

    Energy Technology Data Exchange (ETDEWEB)

    Joe, Kih Soo; Choi, Kwang Soon; Han, Sun Ho; Suh, Moo Yul; Park, Kyung Kyun; Choi, Ke Chun; Kim, Won Ho

    2000-08-01

    KAERI analytical laboratory participated in the 1999 IAEA interlaboratory comparison on chemical analysis of groundwater organized by IAEA Hydrology Laboratory(RAS/8/084). 13 items such as pH, electroconductivity, HCO{sub 3}, Cl, SO{sub 4}, NO{sub 3}, SiO{sub 2}, B, Li, Na, K, Ca, Mg were analyzed. The result of this program showed that KAERI laboratory was ranked within 10% range from top level. An analytical expert in KAERI attended the 'Consultants' Meeting' at IAEA headquater and prepared the guideline for chemical analysis of groundwater.

  6. Chemical analysis and quality control of Ginkgo biloba leaves, extracts, and phytopharmaceuticals

    OpenAIRE

    van Beek; Montoro, P.

    2009-01-01

    The chemical analysis and quality control of Ginkgo leaves, extracts, phytopharmaceuticals and some herbal supplements is comprehensively reviewed. The review is an update of a similar, earlier review in this journal [T.A. van Beek, J. Chromatogr. A 967 (2002) 21¿55]. Since 2001 over 3000 papers on Ginkgo biloba have appeared, and about 400 of them pertain to chemical analysis in a broad sense and are cited herein. The more important ones are discussed and, where relevant, compared with the b...

  7. Scanning angle Raman spectroscopy: Investigation of Raman scatter enhancement techniques for chemical analysis

    Energy Technology Data Exchange (ETDEWEB)

    Meyer, Matthew W. [Iowa State Univ., Ames, IA (United States)

    2013-01-01

    This thesis outlines advancements in Raman scatter enhancement techniques by applying evanescent fields, standing-waves (waveguides) and surface enhancements to increase the generated mean square electric field, which is directly related to the intensity of Raman scattering. These techniques are accomplished by employing scanning angle Raman spectroscopy and surface enhanced Raman spectroscopy. A 1064 nm multichannel Raman spectrometer is discussed for chemical analysis of lignin. Extending dispersive multichannel Raman spectroscopy to 1064 nm reduces the fluorescence interference that can mask the weaker Raman scattering. Overall, these techniques help address the major obstacles in Raman spectroscopy for chemical analysis, which include the inherently weak Raman cross section and susceptibility to fluorescence interference.

  8. Differential dynamic engagement within 24 SH3 domain: peptide complexes revealed by co-linear chemical shift perturbation analysis.

    Directory of Open Access Journals (Sweden)

    Elliott J Stollar

    Full Text Available There is increasing evidence for the functional importance of multiple dynamically populated states within single proteins. However, peptide binding by protein-protein interaction domains, such as the SH3 domain, has generally been considered to involve the full engagement of peptide to the binding surface with minimal dynamics and simple methods to determine dynamics at the binding surface for multiple related complexes have not been described. We have used NMR spectroscopy combined with isothermal titration calorimetry to comprehensively examine the extent of engagement to the yeast Abp1p SH3 domain for 24 different peptides. Over one quarter of the domain residues display co-linear chemical shift perturbation (CCSP behavior, in which the position of a given chemical shift in a complex is co-linear with the same chemical shift in the other complexes, providing evidence that each complex exists as a unique dynamic rapidly inter-converting ensemble. The extent the specificity determining sub-surface of AbpSH3 is engaged as judged by CCSP analysis correlates with structural and thermodynamic measurements as well as with functional data, revealing the basis for significant structural and functional diversity amongst the related complexes. Thus, CCSP analysis can distinguish peptide complexes that may appear identical in terms of general structure and percent peptide occupancy but have significant local binding differences across the interface, affecting their ability to transmit conformational change across the domain and resulting in functional differences.

  9. Size distribution measurements and chemical analysis of aerosol components

    Energy Technology Data Exchange (ETDEWEB)

    Pakkanen, T.A.

    1995-12-31

    The principal aims of this work were to improve the existing methods for size distribution measurements and to draw conclusions about atmospheric and in-stack aerosol chemistry and physics by utilizing size distributions of various aerosol components measured. A sample dissolution with dilute nitric acid in an ultrasonic bath and subsequent graphite furnace atomic absorption spectrometric analysis was found to result in low blank values and good recoveries for several elements in atmospheric fine particle size fractions below 2 {mu}m of equivalent aerodynamic particle diameter (EAD). Furthermore, it turned out that a substantial amount of analyses associated with insoluble material could be recovered since suspensions were formed. The size distribution measurements of in-stack combustion aerosols indicated two modal size distributions for most components measured. The existence of the fine particle mode suggests that a substantial fraction of such elements with two modal size distributions may vaporize and nucleate during the combustion process. In southern Norway, size distributions of atmospheric aerosol components usually exhibited one or two fine particle modes and one or two coarse particle modes. Atmospheric relative humidity values higher than 80% resulted in significant increase of the mass median diameters of the droplet mode. Important local and/or regional sources of As, Br, I, K, Mn, Pb, Sb, Si and Zn were found to exist in southern Norway. The existence of these sources was reflected in the corresponding size distributions determined, and was utilized in the development of a source identification method based on size distribution data. On the Finnish south coast, atmospheric coarse particle nitrate was found to be formed mostly through an atmospheric reaction of nitric acid with existing coarse particle sea salt but reactions and/or adsorption of nitric acid with soil derived particles also occurred. Chloride was depleted when acidic species reacted

  10. Biological and chemical removal of Cr(VI) from waste water: cost and benefit analysis.

    Science.gov (United States)

    Demir, Aynur; Arisoy, Münevver

    2007-08-17

    The objective of the present study is cost and benefit analysis of biological and chemical removal of hexavalent chromium [Cr(VI)] ions. Cost and benefit analysis were done with refer to two separate studies on removal of Cr(VI), one of heavy metals with a crucial role concerning increase in environmental pollution and disturbance of ecological balance, through biological adsorption and chemical ion-exchange. Methods of biological and chemical removal were compared with regard to their cost and percentage in chrome removal. According to the result of the comparison, cost per unit in chemical removal was calculated 0.24 euros and the ratio of chrome removal was 99.68%, whereas those of biological removal were 0.14 and 59.3% euros. Therefore, it was seen that cost per unit in chemical removal and chrome removal ratio were higher than those of biological removal method. In the current study where chrome removal is seen as immeasurable benefit in terms of human health and the environment, percentages of chrome removal were taken as measurable benefit and cost per unit of the chemicals as measurable cost.

  11. An Inverse Analysis Approach to the Characterization of Chemical Transport in Paints

    Science.gov (United States)

    Willis, Matthew P.; Stevenson, Shawn M.; Pearl, Thomas P.; Mantooth, Brent A.

    2014-01-01

    The ability to directly characterize chemical transport and interactions that occur within a material (i.e., subsurface dynamics) is a vital component in understanding contaminant mass transport and the ability to decontaminate materials. If a material is contaminated, over time, the transport of highly toxic chemicals (such as chemical warfare agent species) out of the material can result in vapor exposure or transfer to the skin, which can result in percutaneous exposure to personnel who interact with the material. Due to the high toxicity of chemical warfare agents, the release of trace chemical quantities is of significant concern. Mapping subsurface concentration distribution and transport characteristics of absorbed agents enables exposure hazards to be assessed in untested conditions. Furthermore, these tools can be used to characterize subsurface reaction dynamics to ultimately design improved decontaminants or decontamination procedures. To achieve this goal, an inverse analysis mass transport modeling approach was developed that utilizes time-resolved mass spectroscopy measurements of vapor emission from contaminated paint coatings as the input parameter for calculation of subsurface concentration profiles. Details are provided on sample preparation, including contaminant and material handling, the application of mass spectrometry for the measurement of emitted contaminant vapor, and the implementation of inverse analysis using a physics-based diffusion model to determine transport properties of live chemical warfare agents including distilled mustard (HD) and the nerve agent VX. PMID:25226346

  12. Applying Chemical Imaging Analysis to Improve Our Understanding of Cold Cloud Formation

    Science.gov (United States)

    Laskin, A.; Knopf, D. A.; Wang, B.; Alpert, P. A.; Roedel, T.; Gilles, M. K.; Moffet, R.; Tivanski, A.

    2012-12-01

    The impact that atmospheric ice nucleation has on the global radiation budget is one of the least understood problems in atmospheric sciences. This is in part due to the incomplete understanding of various ice nucleation pathways that lead to ice crystal formation from pre-existing aerosol particles. Studies investigating the ice nucleation propensity of laboratory generated particles indicate that individual particle types are highly selective in their ice nucleating efficiency. This description of heterogeneous ice nucleation would present a challenge when applying to the atmosphere which contains a complex mixture of particles. Here, we employ a combination of micro-spectroscopic and optical single particle analytical methods to relate particle physical and chemical properties with observed water uptake and ice nucleation. Field-collected particles from urban environments impacted by anthropogenic and marine emissions and aging processes are investigated. Single particle characterization is provided by computer controlled scanning electron microscopy with energy dispersive analysis of X-rays (CCSEM/EDX) and scanning transmission X-ray microscopy with near edge X-ray absorption fine structure spectroscopy (STXM/NEXAFS). A particle-on-substrate approach coupled to a vapor controlled cooling-stage and a microscope system is applied to determine the onsets of water uptake and ice nucleation including immersion freezing and deposition ice nucleation as a function of temperature (T) as low as 200 K and relative humidity (RH) up to water saturation. We observe for urban aerosol particles that for T > 230 K the oxidation level affects initial water uptake and that subsequent immersion freezing depends on particle mixing state, e.g. by the presence of insoluble particles. For T cloud formation. Initial results applying single particle IN analysis using CCSEM/EDX and STXM/NEXAFS reveal that a significant amount of IN are coated by organics and, thus, are similar to the

  13. Characterization of soil chemical properties of strawberry fields using principal component analysis

    Directory of Open Access Journals (Sweden)

    Gláucia Oliveira Islabão

    2013-02-01

    Full Text Available One of the largest strawberry-producing municipalities of Rio Grande do Sul (RS is Turuçu, in the South of the State. The strawberry production system adopted by farmers is similar to that used in other regions in Brazil and in the world. The main difference is related to the soil management, which can change the soil chemical properties during the strawberry cycle. This study had the objective of assessing the spatial and temporal distribution of soil fertility parameters using principal component analysis (PCA. Soil sampling was based on topography, dividing the field in three thirds: upper, middle and lower. From each of these thirds, five soil samples were randomly collected in the 0-0.20 m layer, to form a composite sample for each third. Four samples were taken during the strawberry cycle and the following properties were determined: soil organic matter (OM, soil total nitrogen (N, available phosphorus (P and potassium (K, exchangeable calcium (Ca and magnesium (Mg, soil pH (pH, cation exchange capacity (CEC at pH 7.0, soil base (V% and soil aluminum saturation(m%. No spatial variation was observed for any of the studied soil fertility parameters in the strawberry fields and temporal variation was only detected for available K. Phosphorus and K contents were always high or very high from the beginning of the strawberry cycle, while pH values ranged from very low to very high. Principal component analysis allowed the clustering of all strawberry fields based on variables related to soil acidity and organic matter content.

  14. Chemical Analysis of Impurity Boron Atoms in Diamond Using Soft X-ray Emission Spectroscopy

    OpenAIRE

    Muramatsu, Yasuji

    2009-01-01

    To analyze the local structure and/or chemical states of boron atoms in boron-doped diamond, which can be synthesized by the microwave plasma-assisted chemical vapor deposition method (CVD-B-diamond) and the temperature gradient method at high pressure and high temperature (HPT-B-diamond), we measured the soft X-ray emission spectra in the CK and BK regions of B-diamonds using synchrotron radiation at the Advanced Light Source (ALS). X-ray spectral analyses using the fingerprint method and mo...

  15. Quantum mechanics and experimental solid-state nuclear magnetic resonance analysis of strained molecular systems

    Science.gov (United States)

    Halling, Merrill David

    In this work 13C solid-state NMR and quantum mechanical studies of strained molecular systems are discussed. The chemical shift tensor values reported in this document were obtained using the FIREMAT method. Theoretical analyses of chemical shielding tensors were performed through the computer nodes operated by the Utah Center for High Performance Computing. Analyses were performed on sumanene, indenofluoranthene, tetrathiafulvalene, tetrathiafulvalene dimer, [2,2]paracyclophane, and 1,8-dioxa[8](2,7)pyrenophane. The FIREMAT data were fit using the TIGER data processing technique. TIGER provides a means to fit the FIREMAT data, accommodating its unique phase and relaxation characteristics. The details of the FIREMAT experiment are discussed in Chapter 1. The experimentally obtained chemical shift data were compared with calculated chemical shielding data. For these molecular systems, density functional theory was used along with the B3LYP exchange and correlation functionals. Multiple basis sets were used and relatively low errors are reported, between 2.0 ppm and 4.2 ppm. The errors reflect the difference between experimental and theoretical results. The relatively small errors are consistent with those of other polycyclic aromatic hydrocarbons (PAHs) and similar molecular systems. Chapter 2 discusses the three-dimensional aspect of tensor error analysis and how it is used in determining the errors associated with comparing two chemical shift tensors, i.e., theoretically derived and experimentally determined tensors. All error values reported and discussed in this dissertation are determined using this error analysis method. Molecular conformation may be explored by variation in chemical shift tensor principal values. The ring strain in curved polycyclic aromatic hydrocarbons can be associated with downfield shifts in the delta33 component of the chemical shift tensor. This is discussed in Chapters 3 and 5, as it relates to sumanene, indenofluoranthene, [2

  16. [Relativity of commercial specification of Menthae Herba based on chemical analysis].

    Science.gov (United States)

    Ye, Dan; Zhao, Ming; Shao, Yang; Ouyang, Zhen; Peng, Hua-sheng; Han Bang-xing; Zhang, Wei-wan-qi; Gu, Xue-mei

    2015-01-01

    In order to compare the differences of 35 Menthae Herba samples collected on the market and at producing areas, the contents of six total terpenoids, the essential oil and chromatographic fingerprints were analyzed, which provided evidences for drawing up the commodity specifications and grading criteria of Menthae Herba. GC-MS method was used to analyze the chemical constituents of 35 different samples. The chromatographic fingerprints obtained by using GC were then evaluated by similarity analysis, hierarchical clustering analysis and principal component analysis. The relativity between the content of six terpenoids and the essential oil were studied. In this study, the chemical profiles of 35 samples from different producing areas had significant disparity. All samples collected in the report could be categorized into four chemical types, L-menthol, pulegone, carvone and L-menthone, but the chemical profiles had no relationship with the areas. The chromatographic fingerprints of the samples from different types were dissimilar, while the different producing areas were difficult to be separated. It was indicated that the content of volatile oil was positively correlated with the content of L-menthol and the sum of six total terpenoids. The content of the essential oil, L-menthol and the sum of six total terpenoids of Menthae Herba were considered as one of the commercial specifications and grading criteria. These results in the research could be helpful to draw up the commercial specification and grading criteria of Menthae Herba from a view of chemical information.

  17. Electrostatic transition state stabilization rather than reactant destabilization provides the chemical basis for efficient chorismate mutase catalysis.

    Science.gov (United States)

    Burschowsky, Daniel; van Eerde, André; Ökvist, Mats; Kienhöfer, Alexander; Kast, Peter; Hilvert, Donald; Krengel, Ute

    2014-12-09

    For more than half a century, transition state theory has provided a useful framework for understanding the origins of enzyme catalysis. As proposed by Pauling, enzymes accelerate chemical reactions by binding transition states tighter than substrates, thereby lowering the activation energy compared with that of the corresponding uncatalyzed process. This paradigm has been challenged for chorismate mutase (CM), a well-characterized metabolic enzyme that catalyzes the rearrangement of chorismate to prephenate. Calculations have predicted the decisive factor in CM catalysis to be ground state destabilization rather than transition state stabilization. Using X-ray crystallography, we show, in contrast, that a sluggish variant of Bacillus subtilis CM, in which a cationic active-site arginine was replaced by a neutral citrulline, is a poor catalyst even though it effectively preorganizes chorismate for the reaction. A series of high-resolution molecular snapshots of the reaction coordinate, including the apo enzyme, and complexes with substrate, transition state analog and product, demonstrate that an active site, which is only complementary in shape to a reactive substrate conformer, is insufficient for effective catalysis. Instead, as with other enzymes, electrostatic stabilization of the CM transition state appears to be crucial for achieving high reaction rates.

  18. Analysis of initial reactions of MALDI based on chemical properties of matrixes and excitation condition.

    Science.gov (United States)

    Lai, Yin-Hung; Wang, Chia-Chen; Chen, Chiu Wen; Liu, Bo-Hong; Lin, Sheng Hsien; Lee, Yuan Tseh; Wang, Yi-Sheng

    2012-08-16

    This investigation concerns the initial chemical reactions that affect the ionization of matrixes in matrix-assisted laser desorption/ionization (MALDI). The study focuses on the relaxations of photon energy that occur on a comparable time scale to that of ionization, in which the available laser energy is shared and the ionization condition is changed. The relaxations include fluorescence, fragmentation, and nonradiative relaxation from the excited state to the ground state. With high absorption cross section and long excited-state lifetime, photoionization of matrix plays an important role if sufficient laser energy is used. Under other conditions, thermal ionization of the molecule in the ground state is predicted to be one of the important reactions. Evidence of change in the branching ratio of initial reactions with the matrix and the excitation wavelength was obtained with α-cyano-4-hydroxycinnamic acid, sinapinic acid, 2,5-dihydroxybenzoic acid, and 2,4,6-trihydroxyacetophenone. These matrixes are studied by obtaining their mixed crystal absorption spectra, fluorescence properties, laser-induced infrared emission, and product ions. The exact ionization pathway depends on the chemical properties of matrixes and the excitation conditions. This concept may explain the diversity of experimental results observed in MALDI experiments, which provides an insight into the ensemble of chemical reactions that govern the generation of ions.

  19. Step-Scan FTIR spectroscopy and quantum chemical calculations of xanthone in the triplet state

    Science.gov (United States)

    Buschhaus, L.; Kleinermanns, K.

    2014-10-01

    Step-Scan-FTIR spectroscopy has been used to measure the infrared spectrum of xanthone in the triplet state using chloroform as solvent. Xanthone is an important triplet sensitizer and therefore suitable as model system. Xanthone was excited at 266 nm and its IR triplet spectrum measured in the range 1000-1750 cm-1. The spectrum was analyzed by comparison with DFT/B3LYP/TZVP/COSMO calculations. Further on the results were compared to gas phase IR measurements of triplet xanthone and calculations of isolated xanthone. Mainly based on the calculations we tried to identify the geometry changes from the electronic ground state to the first triplet state.

  20. Evaluation of C60 secondary ion mass spectrometry for the chemical analysis and imaging of fingerprints.

    Science.gov (United States)

    Sisco, Edward; Demoranville, Leonard T; Gillen, Greg

    2013-09-10

    The feasibility of using C60(+) cluster primary ion bombardment secondary ion mass spectrometry (C60(+) SIMS) for the analysis of the chemical composition of fingerprints is evaluated. It was found that C60(+) SIMS could be used to detect and image the spatial localization of a number of sebaceous and eccrine components in fingerprints. These analyses were also found to not be hindered by the use of common latent print powder development techniques. Finally, the ability to monitor the depth distribution of fingerprint constituents was found to be possible - a capability which has not been shown using other chemical imaging techniques. This paper illustrates a number of strengths and potential weaknesses of C60(+) SIMS as an additional or complimentary technique for the chemical analysis of fingerprints.

  1. Chemical analysis of bleach and hydroxide-based solutions after decontamination of the chemical warfare agent O-ethyl S-2-diisopropylaminoethyl methylphosphonothiolate (VX).

    Science.gov (United States)

    Hopkins, F B; Gravett, M R; Self, A J; Wang, M; Chua, Hoe-Chee; Hoe-Chee, C; Lee, H S Nancy; Sim, N Lee Hoi; Jones, J T A; Timperley, C M; Riches, J R

    2014-08-01

    Detailed chemical analysis of solutions used to decontaminate chemical warfare agents can be used to support verification and forensic attribution. Decontamination solutions are amongst the most difficult matrices for chemical analysis because of their corrosive and potentially emulsion-based nature. Consequently, there are relatively few publications that report their detailed chemical analysis. This paper describes the application of modern analytical techniques to the analysis of decontamination solutions following decontamination of the chemical warfare agent O-ethyl S-2-diisopropylaminoethyl methylphosphonothiolate (VX). We confirm the formation of N,N-diisopropylformamide and N,N-diisopropylamine following decontamination of VX with hypochlorite-based solution, whereas they were not detected in extracts of hydroxide-based decontamination solutions by nuclear magnetic resonance (NMR) spectroscopy or gas chromatography-mass spectrometry. We report the electron ionisation and chemical ionisation mass spectroscopic details, retention indices, and NMR spectra of N,N-diisopropylformamide and N,N-diisopropylamine, as well as analytical methods suitable for their analysis and identification in solvent extracts and decontamination residues.

  2. Physico-chemical characteristics of honey produced by Apis mellifera in the Picos region, state of Piauí, Brazil

    Directory of Open Access Journals (Sweden)

    Geni da Silva Sodré

    2011-08-01

    Full Text Available The objectives of this research were to determine physico-chemical characteristics of 1,758 Apis mellifera L. honey samples produced by in the productive pole of Picos, state of Piauí, to understand, based on these characteristics, how they are grouped and to determine the percentage of honey that fit the specifications determined by Brazilian legislation. Thirty-five honey samples were collected directly from beekeepers for determination of total sugars, reducing sugars, apparent sucrose, humidity, diastase activity, hydroxymethylfurfural (HMF, protein, ash, pH, acidity, formol index, electrical conductivity, viscosity and color. Mean values of each one of the analyzed physico-chemical parameters are within the limits established by the current Brazilian legislation, but it was verified for apparent sacarosis, diastase activity and HMF, values different from the established ones. Protein and HMF were the traits that contributed most for group formation.

  3. Chemical composition of lipids from native and exotic fish in reservoirs of the state of Ceará, Brazil

    Directory of Open Access Journals (Sweden)

    Selene Maia de Morais

    2016-08-01

    Full Text Available Current study analyzes the chemical composition of lipids in fish commonly found in the dams of the state of Ceará, Brazil, namely Pterygoplichthys pardalis (bodó, Hoplias malabaricus (traira, Cichla ocellaris (tucunaré, Prochilodus brevis (curimatã and Oreochomis niloticus (tilapia. The animals were collected during the summer and Folch extraction procedure was used for the extraction of lipids, whilst Iupac methodology (International Union of Pure and Applied Chemistry [Iupac], 1987 was used to methylate the fatty acids. Methyl esters were analyzed by GC/MS and the different components in fish oil were identified. Palmitic acid, C16:0 (35.71-45.02%, was the saturated fatty acid with the highest percentage, while oleic acid, C18:1Δ9 (10.62-25.29% had the highest percentage among the unsaturated fatty acids. The chemical composition of analyzed freshwater fish lipids revealed low levels of polyunsaturated fatty acids.

  4. Recent Development in Optical Chemical Sensors Coupling with Flow Injection Analysis

    Directory of Open Access Journals (Sweden)

    Fuensanta Sánchez Rojas

    2006-10-01

    Full Text Available Optical techniques for chemical analysis are well established and sensors based on thesetechniques are now attracting considerable attention because of their importance in applications suchas environmental monitoring, biomedical sensing, and industrial process control. On the other hand,flow injection analysis (FIA is advisable for the rapid analysis of microliter volume samples and canbe interfaced directly to the chemical process. The FIA has become a widespread automatic analyticalmethod for more reasons; mainly due to the simplicity and low cost of the setups, their versatility, andease of assembling. In this paper, an overview of flow injection determinations by using opticalchemical sensors is provided, and instrumentation, sensor design, and applications are discussed. Thiswork summarizes the most relevant manuscripts from 1980 to date referred to analysis using opticalchemical sensors in FIA.

  5. SWOT analysis for safer carriage of bulk liquid chemicals in tankers.

    Science.gov (United States)

    Arslan, Ozcan; Er, Ismail Deha

    2008-06-15

    The application of strengths, weaknesses, opportunities and threats (SWOT) analysis to formulation of strategy concerned with the safe carriage of bulk liquid chemicals in maritime tankers was examined in this study. A qualitative investigation using SWOT analysis has been implemented successfully for ships that are designed to carry liquid chemicals in bulk. The originality of this study lies in the use of SWOT analysis as a management tool to formulate strategic action plans for ship management companies, ship masters and officers for the carriage of dangerous goods in bulk. With this transportation-based SWOT analysis, efforts were made to explore the ways and means of converting possible threats into opportunities, and changing weaknesses into strengths; and strategic plans of action were developed for safer tanker operation.

  6. A chemically modified [alpha]-amylase with a molten-globule state has entropically driven enhanced thermal stability

    Energy Technology Data Exchange (ETDEWEB)

    Siddiqui, Khawar Sohail; Poljak, Anne; De Francisci, Davide; Guerriero, Gea; Pilak, Oliver; Burg, Dominic; Raftery, Mark J.; Parkin, Don M.; Trewhella, Jill; Cavicchioli, Ricardo (Sydney); (New South)

    2010-11-15

    The thermostability properties of TAA were investigated by chemically modifying carboxyl groups on the surface of the enzyme with AMEs. The TAA{sub MOD} exhibited a 200% improvement in starch-hydrolyzing productivity at 60 C. By studying the kinetic, thermodynamic and biophysical properties, we found that TAA{sub MOD} had formed a thermostable, MG state, in which the unfolding of the tertiary structure preceded that of the secondary structure by at least 20 C. The X-ray crystal structure of TAA{sub MOD} revealed no new permanent interactions (electrostatic or other) resulting from the modification. By deriving thermodynamic activation parameters of TAA{sub MOD}, we rationalised that thermostabilisation have been caused by a decrease in the entropy of the transition state, rather than being enthalpically driven. Far-UV CD shows that the origin of decreased entropy may have arisen from a higher helical content of TAA{sub MOD}. This study provides new insight into the intriguing properties of an MG state resulting from the chemical modification of TAA.

  7. Direct chemical analysis of frozen ice cores by UV-laser ablation ICPMS

    DEFF Research Database (Denmark)

    Müller, Wolfgang; Shelley, J. Michael G.; Rasmussen, Sune Olander

    2011-01-01

    Cryo-cell UV-LA-ICPMS is a new technique for direct chemical analysis of frozen ice cores at high spatial resolution (ice and reveals sea ice/dust records and annual layer signatures at unprecedented spatial/time resolution. Uniquely......, the location of cation impurities relative to grain boundaries in recrystallized ice can be assessed....

  8. Deconvolution-based resolution enhancement of chemical ice core records obtained by continuous flow analysis

    DEFF Research Database (Denmark)

    Rasmussen, Sune Olander; Andersen, Katrine K.; Johnsen, Sigfus Johann;

    2005-01-01

    Continuous flow analysis (CFA) has become a popular measuring technique for obtaining high-resolution chemical ice core records due to an attractive combination of measuring speed and resolution. However, when analyzing the deeper sections of ice cores or cores from low-accumulation areas, there ...

  9. Evaluation of correlation between chemical dosimetry and subharmonic spectrum analysis to examine the acoustic cavitation.

    Science.gov (United States)

    Hasanzadeh, Hadi; Mokhtari-Dizaji, Manijhe; Bathaie, S Zahra; Hassan, Zuhair M

    2010-06-01

    Currently several therapeutic applications of ultrasound in cancer treatment are under progress which uses cavitation phenomena to deliver their effects. There are several methods to evaluate cavitation activity such as chemical dosimetry and measurement of subharmonic signals. In this study, the cavitation activity induced by the ultrasound irradiation on exposure parameters has been measured by terephthalic acid chemical dosimetry and subharmonic analysis. Experiments were performed in the near 1 MHz fields in the progressive wave mode and effect of duty cycles changes with 2 W/cm(2) intensity (I(SATA)) and acoustic intensity changes in continuous mode on both fluorescence intensity and subharmonic intensity were measured. The dependence between fluorescence intensity of terephthalic acid chemical dosimetry and subharmonic intensity analysis were analyzed by Pearson correlation (p-value subharmonic intensity and the fluorescence intensity for continuous mode is higher than for pulsing mode (p-value subharmonic intensity and the fluorescence intensity with sonication intensity (p-value subharmonic intensity at different duty cycles (R=0.997, p-value subharmonic intensity (microW/cm(2)) significantly correlated with the fluorescence intensity (count) (R=0.901; psubharmonic intensity due to subharmonic spectrum analysis. It is concluded that there is dependence between terephthalic acid chemical dosimetry and subharmonic spectrum analysis to examine the acoustic cavitation activity.

  10. The Matthew effect in environmental science publication: A bibliometric analysis of chemical substances in journal articles

    DEFF Research Database (Denmark)

    Grandjean, Philippe; Eriksen, Mette Lindholm; Ellegaard, Ole

    2011-01-01

    Background While environmental research addresses scientific questions of possible societal relevance, it is unclear to what degree research focuses on environmental chemicals in need of documentation for risk assessment purposes. Methods In a bibliometric analysis, we used SciFinder to extract...

  11. Chemical analysis and quality control of Ginkgo biloba leaves, extracts, and phytopharmaceuticals

    NARCIS (Netherlands)

    Beek, van T.A.; Montoro, P.

    2009-01-01

    The chemical analysis and quality control of Ginkgo leaves, extracts, phytopharmaceuticals and some herbal supplements is comprehensively reviewed. The review is an update of a similar, earlier review in this journal [T.A. van Beek, J. Chromatogr. A 967 (2002) 21¿55]. Since 2001 over 3000 papers on

  12. Fertilizer/Chemical Sales and Service Worker. Ohio's Competency Analysis Profile.

    Science.gov (United States)

    Ohio State Univ., Columbus. Vocational Instructional Materials Lab.

    This Ohio Competency Analysis Profile (OCAP), derived from a modified Developing a Curriculum (DACUM) process, is a current comprehensive and verified employer competency program list for fertilizer/chemical sales and service workers. Each unit (with or without subunits) contains competencies and competency builders that identify the occupational,…

  13. On the graph and systems analysis of reversible chemical reaction networks with mass action kinetics

    NARCIS (Netherlands)

    Rao, Shodhan; Jayawardhana, Bayu; Schaft, Arjan van der

    2012-01-01

    Motivated by the recent progresses on the interplay between the graph theory and systems theory, we revisit the analysis of reversible chemical reaction networks described by mass action kinetics by reformulating it using the graph knowledge of the underlying networks. Based on this formulation, we

  14. Spectral analysis of the light scattered from a chemically relaxing fluid: A ternary mixture

    NARCIS (Netherlands)

    Carle, D.L.; Laidlaw, W.G.; Lekkerkerker, H.N.W.

    1974-01-01

    The spectral distribution of light scattered by a ternary fluid mixture containing two chemically reactive species and one nonreactive species is considered and a normal mode analysis is carried out for a range of k-values for which the pressure fluctuations are decoupled from those in entropy and c

  15. Temporal variation of chemical and mechanical weathering in NE Iceland: Evaluation of a steady-state model of erosion

    Science.gov (United States)

    Eiriksdottir, E. S.; Louvat, P.; Gislason, S. R.; Óskarsson, N.; Hardardóttir, J.

    2008-07-01

    This study critically assesses the temporal sensitivity of the steady-state model of erosion that has been applied to chemical and mechanical weathering studies of volcanic islands and the continents, using only one sample from each catchment. The model assumes a geochemical mass balance between the initially unweathered rock of a drainage basin and the dissolved and solid loads of the river. Chemical composition of 178 samples of suspended and dissolved inorganic river constituents, collected in 1998-2002, were studied from five basaltic river catchments in NE Iceland. The Hydrological Service in Iceland has monitored the discharge and the total suspended inorganic matter concentration (SIM) of the glacial rivers for ~ four decades, making it possible to compare modelled and measured SIM fluxes. Concentration of SIM and grain size increased with discharge. As proportion of clay size particles in the SIM samples increased, concentrations of insoluble elements increased and of soluble decreased. The highest proportion of altered basaltic glass was in the clay size particles. The concentration ratio of insoluble elements in the SIM was used along with data on chemical composition of unweathered rocks (high-Mg basalts, tholeiites, rhyolites) to calculate the pristine composition of the original catchment rocks. The calculated rhyolite proportions compare nicely with area-weighted average proportions, from geological maps of these catchments. The calculated composition of the unweathered bedrock was used in the steady-state model, together with the chemical composition of the suspended and dissolved constituents of the river. Seasonal changes in dissolved constituent concentrations resulted in too low modelled concentrations of SIM mod at high discharge (and too high SIM mod at low discharge). Samples collected at annual average river dissolved load yielded SIM mod concentrations close to the measured ones. According to the model, the studied rivers had specific

  16. Chemical data visualization and analysis with incremental generative topographic mapping: big data challenge.

    Science.gov (United States)

    Gaspar, Héléna A; Baskin, Igor I; Marcou, Gilles; Horvath, Dragos; Varnek, Alexandre

    2015-01-26

    This paper is devoted to the analysis and visualization in 2-dimensional space of large data sets of millions of compounds using the incremental version of generative topographic mapping (iGTM). The iGTM algorithm implemented in the in-house ISIDA-GTM program was applied to a database of more than 2 million compounds combining data sets of 36 chemicals suppliers and the NCI collection, encoded either by MOE descriptors or by MACCS keys. Taking advantage of the probabilistic nature of GTM, several approaches to data analysis were proposed. The chemical space coverage was evaluated using the normalized Shannon entropy. Different views of the data (property landscapes) were obtained by mapping various physical and chemical properties (molecular weight, aqueous solubility, LogP, etc.) onto the iGTM map. The superposition of these views helped to identify the regions in the chemical space populated by compounds with desirable physicochemical profiles and the suppliers providing them. The data sets similarity in the latent space was assessed by applying several metrics (Euclidean distance, Tanimoto and Bhattacharyya coefficients) to data probability distributions based on cumulated responsibility vectors. As a complementary approach, data sets were compared by considering them as individual objects on a meta-GTM map, built on cumulated responsibility vectors or property landscapes produced with iGTM. We believe that the iGTM methodology described in this article represents a fast and reliable way to analyze and visualize large chemical databases.

  17. Sulfur and ash reduction potential and selected chemical and physical properties of United States coals. [Contains glossary

    Energy Technology Data Exchange (ETDEWEB)

    Cavallaro, J.A.; Deurbrouck, A.W.; Killmeyer, R.P.; Fuchs, W. (USDOE Pittsburgh Energy Technology Center, PA (USA). Coal Preparation Div.); Jacobsen, P.S. (Burns and Roe Services Corp., Pittsburgh, PA (USA))

    1991-02-01

    This report presents the washability and comprehensive characterization results of 184 raw coal channel samples, including anthracite, bituminous and lignite coals, collected from the Central Region of the United States. This is the second of a three volume report on the coals of the United States. All the data are presented in six appendices. Statistical techniques and definitions are presented in Appendix A, and a glossary of terms is presented in Appendix B. The complete washability data and an in-depth characterization of each sample are presented alphabetically by state in Appendix C. In Appendix D, a statistical evaluation is given for the composited washability data, selected chemical and physical properties and washability data interpolated at various levels of Btu recovery. This presentation is shown by state, section, and region where four or more samples were collected. Appendix E presents coalbed codes and names for the Central Region coals. Graphical summations are presented by state, section and region showing the effects of crushing on impurity reductions, and the distribution of raw and clean coal samples meeting various levels of SO{sub 2} emissions. 35 figs., 5 tabs.

  18. Sulfur and ash reduction potential and selected chemical and physical properties of United States coals. [Contains glossary

    Energy Technology Data Exchange (ETDEWEB)

    Cavallaro, J.A.; Deurbrouck, A.W.; Killmeyer, R.P.; Fuchs, W. (USDOE Pittsburgh Energy Technology Center, PA (USA)); Jacobsen, P.S. (Burns and Roe Services Corp., Pittsburgh, PA (USA))

    1990-01-01

    This report presents the washability and comprehensive characterization results of 543 raw coal samples collected from the Eastern Region of the United States. This is the first volume of a three-volume report on the coals of the United States. All the data are presented in six appendices. Statistical techniques and definitions are presented in Appendix A, and a glossary of terms is presented in Appendix B. The complete washability data and an in- depth characterization of each sample are presented alphbetically by state in Appendix C. In Appendix D, a statistical evaluation is given for the composited washability data, selected chemical and physical properties, and washability data interpolated at various levels of Btu recovery. This presentation is shown by state, section, and region where four or more samples were collected. Appendix E presents coalbed codes and names for the Eastern Region coals. Graphical summations are presented by state, section, and region showing the effects of crushing on impurity reductions, and the distribution of raw and clean coal samples meeting various levels of SO{sub 2} emissions. 14 refs., 27 figs., 3 tabs.

  19. Petri nets for steady state analysis of metabolic systems.

    Science.gov (United States)

    Voss, Klaus; Heiner, Monika; Koch, Ina

    2011-01-01

    Computer assisted analysis and simulation of biochemical pathways can improve the understanding of the structure and the dynamics of cell processes considerably. The construction and quantitative analysis of kinetic models is often impeded by the lack of reliable data. However, as the topological structure of biochemical systems can be regarded to remain constant in time, a qualitative analysis of a pathway model was shown to be quite promising as it can render a lot of useful knowledge, e. g., about its structural invariants. The topic of this paper are pathways whose substances have reached a dynamic concentration equilibrium (steady state). It is argued that appreciated tools from biochemistry and also low-level Petri nets can yield only part of the desired results, whereas executable high-level net models lead to a number of valuable additional insights by combining symbolic analysis and simulation.

  20. Steady state analysis of metabolic pathways using Petri nets.

    Science.gov (United States)

    Voss, Klaus; Heiner, Monika; Koch, Ina

    2003-01-01

    Computer assisted analysis and simulation of biochemical pathways can improve the understanding of the structure and the dynamics of cell processes considerably. The construction and quantitative analysis of kinetic models is often impeded by the lack of reliable data. However, as the topological structure of biochemical systems can be regarded to remain constant in time, a qualitative analysis of a pathway model was shown to be quite promising as it can render a lot of useful knowledge, e. g., about its structural invariants. The topic of this paper are pathways whose substances have reached a dynamic concentration equilibrium (steady state). It is argued that appreciated tools from biochemistry and also low-level Petri nets can yield only part of the desired results, whereas executable high-level net models lead to a number of valuable additional insights by combining symbolic analysis and simulation.

  1. Analysis of ground state in random bipartite matching

    CERN Document Server

    Shi, Gui-Yuan; Liao, Hao; Zhang, Yi-Cheng

    2015-01-01

    In human society, a lot of social phenomena can be concluded into a mathematical problem called the bipartite matching, one of the most well known model is the marriage problem proposed by Gale and Shapley. In this article, we try to find out some intrinsic properties of the ground state of this model and thus gain more insights and ideas about the matching problem. We apply Kuhn-Munkres Algorithm to find out the numerical ground state solution of the system. The simulation result proves the previous theoretical analysis using replica method. In the result, we also find out the amount of blocking pairs which can be regarded as a representative of the system stability. Furthermore, we discover that the connectivity in the bipartite matching problem has a great impact on the stability of the ground state, and the system will become more unstable if there were more connections between men and women.

  2. Elemental and Chemical State Analysis, XPS, for In-Situ Materials Analysis on Mars Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This innovation is the design of a monochromatic x-ray source to be used in a mission compatible XPS spectrometer. Existing x-ray sources for XPS are large, require...

  3. Elemental and Chemical State Analysis, XPS, for In-Situ Materials Analysis on Mars Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The objective in this project is the development of a monochromatic x-ray source for a small x-ray Photoelectron Spectrometer (XPS) suitable for NASA missions. This...

  4. Explaining state-to-state differences in seat belt use: A multivariate analysis of cultural variables.

    Science.gov (United States)

    Molnar, Lisa J; Eby, David W; Dasgupta, Kohinoor; Yang, Yang; Nair, Vijayan N; Pollock, Stephen M

    2012-07-01

    There is considerable variation in seat belt use within the United States despite extensive evidence that the use of seat belts saves lives. Previous studies have identified some important factors that affect belt use rates, including gender, age, race, vehicle type, seat-belt enforcement laws, and amount of fine for belt-use law violation. In this study, we examined the influence of additional socio-demographic factors on state-level use rates: education (percentage of high school educated population), racial composition (percentage White), median household income, political leaning (percentage Democrat), and a measure of religiosity. These variables, which collectively characterize the 'culture' of a state, have received little attention in seat-belt studies. The paper reports results from a multiple regression analysis of data from the 2008 Fatality Analysis Reporting System (FARS). Many of the use rate patterns in FARS data were consistent with those found in other data sets, suggesting that conclusions based on FARS data are likely to hold for the population-at-large. Of the five cultural factors considered in the study, three were identified as important in explaining the differences in seat belt use at the state level: religiosity, race (percentage White), and political leaning (percentage Democrat). The other two variables - income and education - were not significant. Hold-out analyses confirmed that this conclusion was consistent across different subsets of data. The findings from this study are preliminary and have to be confirmed on other data sets. Nevertheless, they demonstrate the potential usefulness of cultural factors in explaining state-to-state variation in seat belt use rates. If factors such as religiosity are indeed important, they can be used to develop culturally appropriate programs for increasing belt use.

  5. Identification and Analysis of Transition and Metastable Markov States

    CERN Document Server

    Martini, Linda; Hummer, Gerhard; Buchete, Nicolae-Viorel; Rosta, Edina

    2016-01-01

    We present a new method that enables the identification and analysis of both transition and metastable conformational states from atomistic or coarse-grained molecular dynamics (MD) trajectories. Our algorithm is presented and studied by using both analytical and actual examples from MD simulations of the helix-forming peptide Ala5, and of a larger system, the epidermal growth factor receptor (EGFR) protein. In all cases, our method identifies automatically the corresponding transition states and metastable conformations in an optimal way, with the input of a set of relevant coordinates, by capturing accurately the intrinsic slowest relaxation rate. Our approach provides a general and easy to implement analysis method that provides unique insight into the molecular mechanism and the rare but crucial rate limiting conformational pathways occurring in complex dynamical systems such as molecular trajectories.

  6. Phytoestrogens in postmenopause: the state of the art from a chemical, pharmacological and regulatory perspective.

    Science.gov (United States)

    Poluzzi, Elisabetta; Piccinni, Carlo; Raschi, Emanuel; Rampa, Angela; Recanatini, Maurizio; De Ponti, Fabrizio

    2014-01-01

    Phytoestrogens represent a diverse group of non-steroidal natural products, which seem to have some oestrogenic effects and are often marketed as food supplements. Population exposed to phytoestrogens is potentially increasing, in part because an unfavourable risk-benefit profile of Hormone Replacement Therapy (HRT) for prolonged treatments (e.g., osteoporosis prevention) highlighted by the publication of the Women Health Initiative (WHI) trial in 2002, but also because many post-menopausal women often perceived phytoestrogens in food supplements as a safer alternative than HRT. Despite of increasing preclinical and clinical studies in the past decade, appealing evidence is still lacking to support the overall positive risk-benefit profile of phytoestrogens. Their status as food supplements seems to discourage studies to obtain new evidence, and the chance to buy them by user's initiative make it difficult to survey their prevalence and pattern of use. The aim of the present review is to: (a) outline the clinical scenario underlying the increased interest on phytoestrogens, by overviewing the evolution of the evidence on HRT and its main therapeutic goals (e.g., menopausal symptoms relief, chemoprevention, osteoporosis prevention); (b) address the chemical and pharmacological features (e.g. chemical structure, botanical sources, mechanism of action) of the main compounds (e.g., isoflavones, lignans, coumestans); (c) describe the clinical evidence on potential therapeutic applications; (d) put available evidence on their riskbenefit profile in a regulatory perspective, in light of the recent regulation on health claims of food supplements.

  7. On the binary helium star DY Centauri: chemical composition and evolutionary state

    Energy Technology Data Exchange (ETDEWEB)

    Pandey, Gajendra; Rao, N. Kameswara [Indian Institute of Astrophysics, Bangalore 560034 (India); Jeffery, C. Simon [Armagh Observatory, Collage Hill, Armagh BT61 9DG (United Kingdom); Lambert, David L., E-mail: pandey@iiap.res.in, E-mail: nkrao@iiap.res.in, E-mail: csj@arm.ac.uk, E-mail: dll@astro.as.utexas.edu [The W. J. McDonald Observatory and Department of Astronomy, University of Texas at Austin, Austin, TX 78712-1083 (United States)

    2014-10-01

    DY Cen has shown a steady fading of its visual light by about one magnitude in the last 40 yr, suggesting a secular increase in its effective temperature. We have conducted non-local thermodynamic equilibrium (LTE) and LTE abundance analyses to determine the star's effective temperature, surface gravity, and chemical composition using high-resolution spectra obtained over two decades. The derived stellar parameters for three epochs suggest that DY Cen has evolved at a constant luminosity and has become hotter by about 5000 K in 23 yr. We show that the derived abundances remain unchanged for the three epochs. The derived abundances of the key elements, including F and Ne, are as observed for the extreme helium stars resulting from a merger of a He white dwarf with a C-O white dwarf. Thus DY Cen by chemical composition appears to also be a product of a merger of two white dwarfs. This appearance seems to be at odds with the recent suggestion that DY Cen is a single-lined spectroscopic binary.

  8. Chemical vapor transport and solid-state exchange synthesis of new copper selenite bromides

    Science.gov (United States)

    Charkin, Dmitri O.; Kayukov, Roman A.; Zagidullin, Karim A.; Siidra, Oleg I.

    2017-02-01

    A new dimorphic copper selenite bromide, Cu5(SeO3)4Br2 was obtained via chemical transport reactions. α-Cu5(SeO3)4Br2, monoclinic (1m) and β-Cu5(SeO3)4Br2, triclinic (1a) polymorphs were produced simultaneously upon reaction of amorphous, partially dehydrated copper selenite and copper bromide. 1m is similar to Cu5(SeO3)4Cl2, whereas 1a is distantly related to Ni5(SeO3)4Br2 and Co5(SeO3)4Br2. Attempts to reproduce synthesis of 1a via exchange reaction between Na2SeO3 and CuBr2 resulted in a new Na2[Cu7O2](SeO3)4Br4 (2). Current study demonstrates for the first time, that both chemical vapor and exchange reactions can be employed in preparation of new selenite halides.

  9. Microsolvated transition state models for improved insight into chemical properties and reaction mechanisms.

    Science.gov (United States)

    Sunoj, Raghavan B; Anand, Megha

    2012-10-05

    Over the years, several methods have been developed to effectively represent the chemical behavior of solutes in solvents. The environmental effects arising due to solvation can generally be achieved either through inclusion of discrete solvent molecules or by inscribing into a cavity in a homogeneous and continuum dielectric medium. In both these approaches of computational origin, the perturbations on the solute induced by the surrounding solvent are at the focus of the problem. While the rigor and method of inclusion of solvent effects vary, such solvation models have found widespread applications, as evident from modern chemical literature. A hybrid method, commonly referred to as cluster-continuum model (CCM), brings together the key advantages of discrete and continuum models. In this perspective, we intend to highlight the latent potential of CCM toward obtaining accurate estimates on a number of properties as well as reactions of contemporary significance. The objective has generally been achieved by choosing illustrative examples from the literature, besides expending efforts to bring out the complementary advantages of CCM as compared to continuum or discrete solvation models. The majority of examples emanate from the prevalent applications of CCM to organic reactions, although a handful of interesting organometallic reactions have also been discussed. In addition, increasingly accurate computations of properties like pK(a) and solvation of ions obtained using the CCM protocol are also presented.

  10. Analysis of Physiochemical Parameters to Evaluate the Drinking Water Quality in the State of Perak, Malaysia

    Directory of Open Access Journals (Sweden)

    N. Rahmanian

    2015-01-01

    Full Text Available The drinking water quality was investigated in suspected parts of Perak state, Malaysia, to ensure the continuous supply of clean and safe drinking water for the public health protection. In this regard, a detailed physical and chemical analysis of drinking water samples was carried out in different residential and commercial areas of the state. A number of parameters such as pH, turbidity, conductivity, total suspended solids (TSS, total dissolved solids (TDS, and heavy metals such as Cu, Zn, Mg, Fe, Cd, Pb, Cr, As, Hg, and Sn were analysed for each water sample collected during winter and summer periods. The obtained values of each parameter were compared with the standard values set by the World Health Organization (WHO and local standards such as National Drinking Water Quality Standard (NDWQS. The values of each parameter were found to be within the safe limits set by the WHO and NDWQS. Overall, the water from all the locations was found to be safe as drinking water. However, it is also important to investigate other potential water contaminations such as chemicals and microbial and radiological materials for a longer period of time, including human body fluids, in order to assess the overall water quality of Perak state.

  11. Visualization and data analysis-current state and exascale challenges

    Energy Technology Data Exchange (ETDEWEB)

    Ahrens, James P [Los Alamos National Laboratory; Rodgers, David [SNL; Springmeyer, Becky [LLNL

    2010-12-21

    Talk about Visualization and Data Analysis Current State and Exascale challenges. The goal is to update with colleagues our current status in our research. What challenges we need to face, and what future possibilities. Our goal is to propose to approach the problems with the visualization approach operating on the supercomputing platform. This presentation is about the L2 Milestone, we intend to discuss further possibilities of enhancing our results and optimizing our solutions.

  12. Covellite CuS as a matrix for "invisible" gold: X-ray spectroscopic study of the chemical state of Cu and Au in synthetic minerals

    Science.gov (United States)

    Tagirov, Boris R.; Trigub, Alexander L.; Kvashnina, Kristina O.; Shiryaev, Andrey A.; Chareev, Dmitriy A.; Nickolsky, Maximilian S.; Abramova, Vera D.; Kovalchuk, Elena V.

    2016-10-01

    .3 for both positions of Cu. This result is confirmed by theoretical analysis of electron density performed using quantum theory of atoms in molecules (QTAIM). Modeling of the Au L3 edge EXAFS/XANES spectra showed that Au in covellite exists in the form of the isomorphous solid solution formed by substitution for Cu atoms in triangular coordination with the Me-S distance in the first coordination shell increased by 0.18 Å relative to the pure CuS structure. The "formal" oxidation state of Au in covellite is +1. The Bader partial atomic charge for Au in covellite is lower than the charge of Cu (+0.2 e vs. +0.5 e) indicating that the degree of covalency for the Au-bearing covellite is higher than that of pure CuS. The analysis of electronic density of states shows that this structural position of Au results in strong interactions between hybridized Au s,p,d, S p, and Cu p,d orbitals. Such chemical bonding of Au to S and Cu can result in the formation of Au-bearing solid solution with other minerals in the Cu-Fe-S system.

  13. Impact analysis of different chemical pre-treatments on colour of apple discs during drying process

    OpenAIRE

    D. Magdić; Lukinac, Jasmina; Jokić, Stela; Čačić-Kenjerić, F.; Bilić, M.; Velić, D.

    2009-01-01

    The main purpose of this study was to compare colour changes of chemically pre-treated dried apple discs. Changes were observed by chromameter in L*a*b* colour model by using Minolta chromameter CR-400 and by image analysis system in RGB colour model. Apple discs variety "Gold Rush" were pre-treated and dried in laboratory tray drier at drying temperature 70 °C and at airflow velocity of 1.5 ms-1. Different chemical pre-treatments were applied on apple discs (dipping in 0.5% ascorbic acid sol...

  14. Integrated label-free silicon nanowire sensor arrays for (bio)chemical analysis.

    Science.gov (United States)

    De, Arpita; van Nieuwkasteele, Jan; Carlen, Edwin T; van den Berg, Albert

    2013-06-07

    We present a label-free (bio)chemical analysis platform that uses all-electrical silicon nanowire sensor arrays integrated with a small volume microfluidic flow-cell for real-time (bio)chemical analysis and detection. The integrated sensing platform contains an automated multi-sample injection system that eliminates erroneous sensor responses from sample switching due to flow rate fluctuations and provides precise sample volumes down to 10 nl. Biochemical sensing is demonstrated with real-time 15-mer DNA-PNA (peptide nucleic acid) duplex hybridization measurements from different sample concentrations in a low ionic strength, and the equilibrium dissociation constant KD ≈ 140 nM has been extracted from the experimental data using the first order Langmuir binding model. Chemical sensing is demonstrated with pH measurements from different injected samples in flow that have sensitivities consistent with the gate-oxide materials. A differential sensor measurement configuration results in a 30× reduction in sensor drift. The integrated label-free analysis platform is suitable for a wide range of small volume chemical and biochemical analyses.

  15. Hyaloperonospora camelinae on Camelina sativa (L.) in Washington State: Detection, seed transmission, and chemical control

    Science.gov (United States)

    Camelina (Camelina sativa [L.] Crantz) plants with symptoms of downy mildew were obtained from three different locations in Washington State. Based on PCR and sequencing of the ITS1-5.8S-ITS2 region, the causal pathogen was identified as Hyaloperonospora camelinae. The PCR primers consistently ampli...

  16. LSENS: A General Chemical Kinetics and Sensitivity Analysis Code for homogeneous gas-phase reactions. Part 1: Theory and numerical solution procedures

    Science.gov (United States)

    Radhakrishnan, Krishnan

    1994-01-01

    LSENS, the Lewis General Chemical Kinetics and Sensitivity Analysis Code, has been developed for solving complex, homogeneous, gas-phase chemical kinetics problems and contains sensitivity analysis for a variety of problems, including nonisothermal situations. This report is part 1 of a series of three reference publications that describe LENS, provide a detailed guide to its usage, and present many example problems. Part 1 derives the governing equations and describes the numerical solution procedures for the types of problems that can be solved. The accuracy and efficiency of LSENS are examined by means of various test problems, and comparisons with other methods and codes are presented. LSENS is a flexible, convenient, accurate, and efficient solver for chemical reaction problems such as static system; steady, one-dimensional, inviscid flow; reaction behind incident shock wave, including boundary layer correction; and perfectly stirred (highly backmixed) reactor. In addition, the chemical equilibrium state can be computed for the following assigned states: temperature and pressure, enthalpy and pressure, temperature and volume, and internal energy and volume. For static problems the code computes the sensitivity coefficients of the dependent variables and their temporal derivatives with respect to the initial values of the dependent variables and/or the three rate coefficient parameters of the chemical reactions.

  17. Multivariate analysis of the chemical properties of the eroded brown soils

    Directory of Open Access Journals (Sweden)

    Juan Alejandro Villazón Gómez

    2017-01-01

    Full Text Available The work was carried out with the data obtained of 30 profiles of Brown soils classified according to the effect of erosion. With the objective of determining, by means of a multivariate analysis, the effect of the erosion on the chemicals properties of the Brown soils was carried out a Discriminant and Principals Components Analysis. It was evaluated the chemicals variables pH in water, pH in KCl, organic matter, calcium, magnesium, potassium, sodium and S, T and V values. The Multivariate Analysis allowed establishing that magnesium is the only chemical property that evidence contraposition with the other variables, due to the harmful effect that this base exerts on the soil aggregates, which can accelerate or stressing the action of the erosive processes in the Brown soils. In the Principals Components Analysis, then components represented by the influence of the soil reaction, the absorbing complex and magnesium accumulate 78.75 % of the variance. The Discriminant Analysis explains the 97.06 % of the total of the variation in the two first axes, with the 93.33 % of good classification, with all the groups conformed by the categories of erosion well told apart among themselves.

  18. The challenges and limitations of chemical analysis of particulate pigments of very low solubility.

    Science.gov (United States)

    Olsen, Ole

    2015-01-01

    When performing a chemical analysis of colorants in tattoo products, specific degradation products as well as impurity patterns can be predicted. Mislabeling or false declarations can also be avoided using this test. It is notable that pigment identification in tattoo products may serve as a precursory technique to recognize the colorants contained in a patient's tattoo prior to laser removal therapy. In contrast to the analysis of banned pigments, positive identification of pigments will normally require few reference substances. Given the fact that tattoo pigments are nearly insoluble in water and many organic solvents, different chemical pigment analyses are outlined and evaluated. Related publications from the study of art are also mentioned. It is recommended that access to comprehensive pigment standards and spectroscopic databanks should be offered to laboratories dealing with tattoo product analysis in the future.

  19. Sampling and chemical analysis in environmental samples around Nuclear Power Plants and some environmental samples

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Yong Woo; Han, Man Jung; Cho, Seong Won; Cho, Hong Jun; Oh, Hyeon Kyun; Lee, Jeong Min; Chang, Jae Sook [KORTIC, Taejon (Korea, Republic of)

    2002-12-15

    Twelve kinds of environmental samples such as soil, seawater, underground water, etc. around Nuclear Power Plants(NPPs) were collected. Tritium chemical analysis was tried for the samples of rain water, pine-needle, air, seawater, underground water, chinese cabbage, a grain of rice and milk sampled around NPPs, and surface seawater and rain water sampled over the country. Strontium in the soil that sere sampled at 60 point of district in Korea were analyzed. Tritium were sampled at 60 point of district in Korea were analyzed. Tritium were analyzed in 21 samples of surface seawater around the Korea peninsular that were supplied from KFRDI(National Fisheries Research and Development Institute). Sampling and chemical analysis environmental samples around Kori, Woolsung, Youngkwang, Wooljin Npps and Taeduk science town for tritium and strontium analysis was managed according to plans. Succeed to KINS after all samples were tried.

  20. Estimates of agricultural-chemical use in counties in the conterminous United States as reported in the 1987 Census of Agriculture

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This coverage contains estimates of agricultural-chemical use in counties in the conterminous United States as reported in the 1987 Census of Agriculture (U.S....

  1. Humidity independent mass spectrometry for gas phase chemical analysis via ambient proton transfer reaction

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Hongying; Huang, Guangming, E-mail: gmhuang@ustc.edu.cn

    2015-03-31

    Graphical abstract: Direct and humidity independent mass spectrometry analysis of gas phase chemicals could be achieved via ambient proton transfer ionization, ion intensity was found to be stable with humidity ranged from ∼10% to ∼100%. - Highlights: • A humidity independent mass spectrometric method for gas phase samples analysis. • A universal and good sensitivity method. • The method can real time identify plant released raw chemicals. - Abstract: In this work, a humidity independent mass spectrometric method was developed for rapid analysis of gas phase chemicals. This method is based upon ambient proton transfer reaction between gas phase chemicals and charged water droplets, in a reaction chamber with nearly saturate humidity under atmospheric pressure. The humidity independent nature enables direct and rapid analysis of raw gas phase samples, avoiding time- and sample-consuming sample pretreatments in conventional mass spectrometry methods to control sample humidity. Acetone, benzene, toluene, ethylbenzene and meta-xylene were used to evaluate the analytical performance of present method. The limits of detection for benzene, toluene, ethylbenzene and meta-xylene are in the range of ∼0.1 to ∼0.3 ppbV; that of benzene is well below the present European Union permissible exposure limit for benzene vapor (5 μg m{sup −3}, ∼1.44 ppbV), with linear ranges of approximately two orders of magnitude. The majority of the homemade device contains a stainless steel tube as reaction chamber and an ultrasonic humidifier as the source of charged water droplets, which makes this cheap device easy to assemble and facile to operate. In addition, potential application of this method was illustrated by the real time identification of raw gas phase chemicals released from plants at different physiological stages.

  2. Chemical and biochemical properties of Araucaria angustifolia (Bert. Ktze. forest soils in the state of São Paulo

    Directory of Open Access Journals (Sweden)

    Fernanda de Carvalho

    2012-08-01

    Full Text Available Araucaria angustifolia, commonly named Araucaria, is a Brazilian native species that is intensively exploited due to its timber quality. Therefore, Araucaria is on the list of species threatened by extinction. Despite the importance of soil for forest production, little is known about the soil properties of the highly fragmented Araucaria forests. This study was designed to investigate the use of chemical and biological properties as indicators of conservation and anthropogenic disturbance of Araucaria forests in different sampling periods. The research was carried out in two State parks of São Paulo: Parque Estadual Turístico do Alto do Ribeira and Parque Estadual de Campos de Jordão. The biochemical properties carbon and nitrogen in microbial biomass (MB-C and MB-N, basal respiration (BR, the metabolic quotient (qCO2 and the following enzyme activities: β-glucosidase, urease, and fluorescein diacetate hydrolysis (FDA were evaluated. The sampling period (dry or rainy season influenced the results of mainly MB-C, MB-N, BR, and qCO2. The chemical and biochemical properties, except K content, were sensitive indicators of differences in the conservation and anthropogenic disturbance stages of Araucaria forests. Although these forests differ in biochemical and chemical properties, they are efficient in energy use and conservation, which is shown by their low qCO2, suggesting an advanced stage of succession.

  3. Determination of chemical elements in africanized Apis mellifera (Hymenoptera: Apidae honey samples from the State of Piauí, Brazil

    Directory of Open Access Journals (Sweden)

    Geni da Silva Sodré

    2007-08-01

    Full Text Available Honey is a food used since the most remote times, appreciated for its characteristic flavor, considerable nutritional value and medicinal properties; however, little information exists about the presence of chemical elements in it. The objectives of this work were to determine the chemical elements present in 38 honey samples, collected directly from beekeepers from the State of Piauí, Brazil and to verify whether they presented any contamination. The chemical elements were determined by means of Total Reflection X-ray Fluorescence. The means of three replicates were: K (109.671 ± 17.487, Ca (14.471 ± 3.8797, Ti (0.112 ± 0.07, Cr (0.196 ± 0.11, Mn (0.493 ± 0.103, Fe (1.722 ± 0.446, Co (0.038, Ni (0.728 ± 0.706, Cu (0.179 ± 0.0471, Zn (0.967 ± 0.653, Se (not detected, Br (not detected, Rb (0.371 ± 0.097, Sr (0.145 ± 0.45, Ba (11.681, Hg (not detected, and Pb (0.863 µg g-1.

  4. Small targeted cytotoxics: current state and promises from DNA-encoded chemical libraries.

    Science.gov (United States)

    Krall, Nikolaus; Scheuermann, Jörg; Neri, Dario

    2013-01-28

    The targeted delivery of potent cytotoxic agents has emerged as a promising strategy for the treatment of cancer and other serious conditions. Traditionally, antibodies against markers of disease have been used as drug-delivery vehicles. More recently, lower molecular weight ligands have been proposed for the generation of a novel class of targeted cytotoxics with improved properties. Advances in this field crucially rely on efficient methods for the identification and optimization of organic molecules capable of high-affinity binding and selective recognition of target proteins. The advent of DNA-encoded chemical libraries allows the construction and screening of compound collections of unprecedented size. In this Review, we survey developments in the field of small ligand-based targeted cytotoxics and show how innovative library technologies will help develop the drugs of the future.

  5. Changes in the chemical structure of polytetrafluoroethylene induced by electron beam irradiation in the molten state

    CERN Document Server

    Lappan, U; Lunkwitz, K

    2000-01-01

    Polytetrafluoroethylene (PTFE) was exposed to electron beam radiation at elevated temperature above the melting point under nitrogen atmosphere and in vacuum for comparison. Fourier-transform infrared (FTIR) spectroscopy was used to study the changes in the chemical structure. The irradiation under nitrogen atmosphere leads to the same structures as described recently for PTFE irradiated in vacuum. Trifluoromethyl branches and double bond structures were detected. The concentrations of terminal and internal double bonds are higher after irradiation under nitrogen than in vacuum. Annealing experiments have shown that the thermal oxidative stability of the radiation-modified PTFE is reduced compared to unirradiated PTFE. The reason are the formation of unstable structures such as double bonds.

  6. High sensitivity detection and characterization of the chemical state of trace element contamination on silicon wafers

    CERN Document Server

    Pianetta, Piero A; Baur, K; Brennan, S; Homma, T; Kubo, N

    2003-01-01

    Increasing the speed and complexity of semiconductor integrated circuits requires advanced processes that put extreme constraints on the level of metal contamination allowed on the surfaces of silicon wafers. Such contamination degrades the performance of the ultrathin SiO sub 2 gate dielectrics that form the heart of the individual transistors. Ultimately, reliability and yield are reduced to levels that must be improved before new processes can be put into production. It should be noted that much of this metal contamination occurs during the wet chemical etching and rinsing steps required for the manufacture of integrated circuits and industry is actively developing new processes that have already brought the metal contamination to levels beyond the measurement capabilities of conventional analytical techniques. The measurement of these extremely low contamination levels has required the use of synchrotron radiation total reflection X-ray fluorescence (SR-TXRF) where sensitivities 100 times better than conv...

  7. Theory of NMR chemical shift in an electronic state with arbitrary degeneracy

    CERN Document Server

    Heuvel, Willem Van den

    2012-01-01

    We present a theory of nuclear magnetic resonance (NMR) shielding tensors for electronic states with arbitrary degeneracy. The shieldings are here expressed in terms of generalized Zeeman ($g^{(k)}$) and hyperfine ($A^{(k)}$) tensors, of all ranks $k$ allowed by the size of degeneracy. Contrary to recent proposals [T. O. Pennanen and J. Vaara, Phys. Rev. Lett. 100, 133002 (2008)], our theory is valid in the strong spin-orbit coupling limit. Ab initio calculations for the 4-fold degenerate $\\Gamma_8$ ground state of lanthanide-doped fluorite crystals CaF$_2$:Ln (Ln = Pr$^{2+}$, Nd$^{3+}$, Sm$^{3+}$, and Dy$^{3+}$) show that previously neglected contributions can account for more than 50% of the paramagnetic shift.

  8. Error sensitivity to environmental noise in quantum circuits for chemical state preparation

    CERN Document Server

    Sawaya, Nicolas P D; McClean, Jarrod R; Aspuru-Guzik, Alán

    2016-01-01

    Calculating molecular energies is likely to be one of the first useful applications to achieve quantum supremacy, performing faster on a quantum than a classical computer. However, if future quantum devices are to produce accurate calculations, errors due to environmental noise and algorithmic approximations need to be characterized and reduced. In this study, we use the high performance qHiPSTER software to investigate the effects of environmental noise on the preparation of quantum chemistry states. We simulate nineteen 16-qubit quantum circuits under environmental noise, each corresponding to a unitary coupled cluster state preparation of a different molecule or molecular configuration. Additionally, we analyze the nature of simple gate errors in noise-free circuits of up to 40 qubits. We find that the Jordan-Wigner (JW) encoding produces consistently smaller errors under a noisy environment as compared to the Bravyi-Kitaev (BK) encoding. For the JW encoding, pure-dephasing noise is shown to produce substa...

  9. State Key Laboratory of Catalysis Dalian Institute of Chemical Physics, China

    Institute of Scientific and Technical Information of China (English)

    Can Li

    2002-01-01

    @@ I. Introduction The State Key Laboratory of Catalysis (SKLC)was founded in 1987 as one of the first state key labo-ratories in China. The current director of the SKLC isProfessor Can Li (the previous directors were Profes-sor Xiexian Guo and Professor Yide Xu). ProfessorLiwu Lin chairs the Academic Committee, which iscomposed of 15 distinguished Chinese catalytic scien-tists. In addition, the SKLC appoints internationallyknown scientists in the field of catalysis to its Inter-national Advisory Committee. There are about 35permanent staff members including professors, tech-nicians, and administrators, over 80 Ph.D. and M.S.graduate students and 10 post-doctoral fellows.

  10. Excited State Properties of Fluorine-Substituted Hexabenzocoronene: A Quantum-Chemical Characterization

    Institute of Scientific and Technical Information of China (English)

    LI Yuan-Zuo; SUN Yu; LI Yong-Qing; MA Feng-Cai

    2006-01-01

    The first fluorine-substituted hexabenzocoronene has been synthesized and its electronic structure and optical properties have been reported [Q. Zhang, et al., Org. Lett.7 (2005) 5019]. In this letter, the electronic structure and excited state properties of the fluorine-substituted hexabenzocoronene are studied with quantum chemistry method as well as the transition and the charge difference densities. The transition densities show the orientations and strength of the dipole moments and the charge difference densities reveal the orientation and results of the intramolecular charge transfer. The calculated transition energies and oscillator strengths are consistent with the experimental data, and the theoretical results of transition and charge difference densities are valuable to understanding the excited state properties of the fluorine-substituted hexabenzocoronene.

  11. Survey of chemical disinfectants used by poultry farmers in Imo state, Nigeria.

    Directory of Open Access Journals (Sweden)

    I.U. Chima

    2011-09-01

    Full Text Available Pathogen contamination can be prevented with aid of proper health care products such as disinfectants. This study was designed to evaluate the efficacy of common disinfectants and disinfection practice of poultry farmers in Imo State, Nigeria, in order to generate information needed for the proper regulation of disinfectant use in the area. Primary data were generated from structured questionnaires distributed to animal health practitioners and poultry farmers in the State. Results showed that farmers choice of disinfectants were dependent on cost and availability. Z-germicide® 10 (22.27% and Izal® with 9 (20.45% are more widely distributed in the various animal health outfits. This was closely followed by Lysol® 6 (13.63% and Diskol® 6 (13.63%. Morigard® 3 (6.81%, Dettol® and Septol® 3 (6.81% appeared each in three outfits. Vox® 1 (2.27% CID 20® 1 (2.27% a Virkon® 1 (2.27% occurred once and that is at the Avian influenza desk officer’s store. Izal® 140 (58.82 was more widely used by farmers followed by Z-germicide®, both of which are phenolic products. Morigad® with 2 (2.94% and Lysol® with 91.47%0 are also phenolic products. Altogether 76.47% of disinfectants used in Imo State were of phenolic products. Most poultry farms in the State did not use disinfectant footbath. Those that used them did not insist on workers or visitors dipping their feet in them before entering the farm house. They also did not reconstitute the disinfectants according to the manufacturer’s instructions.

  12. Integration of Biological Specificity with Solid-State Devices for Selective Chemical Sensing

    Science.gov (United States)

    2016-01-29

    transferred from air into a liquid or hydrogel layer that passes over a bank of aptamer functionalized sensor arrays. Figure 5. A multi-tip nanoscale...see any limitations for the integration of solid-state aptamer sensors with liquid flow cells. We have also investigated the scaling of chemiresistors...complex 3D structure. However, we did not test the aptamer against the ATP target, because the latter requires a liquid solution environment and our

  13. Resonant impurity states in chemically disordered half-Heusler Dirac semimetals

    Science.gov (United States)

    Chadova, K.; Ködderitzsch, D.; Minár, J.; Ebert, H.; Kiss, J.; D'Souza, S. W.; Wollmann, L.; Felser, C.; Chadov, S.

    2016-05-01

    We address the electron transport characteristics in bulk half-Heusler alloys with their compositions tuned to the borderline between topologically nontrivial semimetallic and trivial semiconducting phases. Accurate first-principles calculations based on the coherent potential approximation (CPA) reveal that all the studied systems exhibit sets of dispersionless impurity-like resonant levels, with one of them being located at the Dirac point. By means of the Kubo-Bastin formalism we reveal that the residual conductivity of these alloys is strongly suppressed by impurity scattering, whereas the spin Hall conductivity exhibits a rather complex behavior induced by the resonant states. In particular for LaPt0.5Pd0.5Bi we find that the total spin Hall conductivity is strongly suppressed by two large and opposite contributions: the negative Fermi-surface contribution produced by the resonant impurity and the positive Fermi-sea term stemming from the occupied states. At the same time, we identify no conductivity contributions from the conical states.

  14. IGE Model: An Extension of the Ideal Gas Model to Include Chemical Composition as Part of the Equilibrium State

    Directory of Open Access Journals (Sweden)

    Christopher P. Paolini

    2012-01-01

    Full Text Available The ideal gas (IG model is probably the most well-known gas models in engineering thermodynamics. In this paper, we extend the IG model into an ideal gas equilibrium (IGE model mixture model by incorporating chemical equilibrium calculations as part of the state evaluation. Through a simple graphical interface, users can set the atomic composition of a gas mixture. We have integrated this model into a thermodynamic web portal TEST (http://thermofluids.sdsu.edu/ that contains Java applets for various models for properties of pure substances. In the state panel of the IGE model, the known thermodynamic properties are entered. For a given pressure and temperature, the mixture's Gibbs function is minimized subject to atomic constraints and the equilibrium composition along with thermodynamic properties of the mixture are calculated and displayed. What is unique about this approach is that equilibrium computations are performed in the background, without requiring any major change in the familiar user interface used in other state daemons. Properties calculated by this equilibrium state daemon are compared with results from other established applications such as NASA CEA and STANJAN. Also, two different algorithms, an iterative approach and a direct approach based on minimizing different thermodynamic functions in different situation, are compared.

  15. Preliminary Analysis of a Fully Solid State Magnetocaloric Refrigeration

    Energy Technology Data Exchange (ETDEWEB)

    Abdelaziz, Omar [ORNL

    2016-01-01

    Magnetocaloric refrigeration is an alternative refrigeration technology with significant potential energy savings compared to conventional vapor compression refrigeration technology. Most of the reported active magnetic regenerator (AMR) systems that operate based on the magnetocaloric effect use heat transfer fluid to exchange heat, which results in complicated mechanical subsystems and components such as rotating valves and hydraulic pumps. In this paper, we propose an alternative mechanism for heat transfer between the AMR and the heat source/sink. High-conductivity moving rods/sheets (e.g. copper, brass, iron, graphite, aluminum or composite structures from these) are utilized instead of heat transfer fluid significantly enhancing the heat transfer rate hence cooling/heating capacity. A one-dimensional model is developed to study the solid state AMR. In this model, the heat exchange between the solid-solid interfaces is modeled via a contact conductance, which depends on the interface apparent pressure, material hardness, thermal conductivity, surface roughness, surface slope between the interfaces, and material filled in the gap between the interfaces. Due to the tremendous impact of the heat exchange on the AMR cycle performance, a sensitivity analysis is conducted employing a response surface method, in which the apparent pressure, effective surface roughness and grease thermal conductivity are the uncertainty factors. COP and refrigeration capacity are presented as the response in the sensitivity analysis to reveal the important factors influencing the fully solid state AMR and optimize the solid state AMR efficiency. The performances of fully solid state AMR and traditional AMR are also compared and discussed in present work. The results of this study will provide general guidelines for designing high performance solid state AMR systems.

  16. Surface chemical state of Ti powders and its alloys: Effect of storage conditions and alloy composition

    Science.gov (United States)

    Hryha, Eduard; Shvab, Ruslan; Bram, Martin; Bitzer, Martin; Nyborg, Lars

    2016-12-01

    High affinity of titanium to oxygen in combination with the high surface area of the powder results in tremendous powder reactivity and almost inevitable presence of passivation oxide film on the powder surface. Oxide film is formed during the short exposure of the powder to the environment at even a trace amount of oxygen. Hence, surface state of the powder determines its usefulness for powder metallurgy processing. Present study is focused on the evaluation of the surface oxide state of the Ti, NiTi and Ti6Al4V powders in as-atomized state and after storage under air or Ar for up to eight years. Powder surface oxide state was studied by X-ray photoelectron spectroscopy (XPS) and high resolution scanning electron microscopy (HR SEM). Results indicate that powder in as-atomized state is covered by homogeneous Ti-oxide layer with the thickness of ∼2.9 nm for Ti, ∼3.2 nm and ∼4.2 nm in case of Ti6Al4V and NiTi powders, respectively. Exposure to the air results in oxide growth of about 30% in case of Ti and only about 10% in case of NiTi and Ti6Al4V. After the storage under the dry air for two years oxide growth of only about 3-4% was detected in case of both, Ti and NiTi powders. NiTi powder, stored under the dry air for eight years, indicates oxide thickness of about 5.3 nm, which is about 30% thicker in comparison with the as-atomized powder. Oxide thickness increase of only ∼15% during the storage for eight years in comparison with the powder, shortly exposed to the air after manufacturing, was detected. Results indicate a high passivation of the Ti, Ti6Al4V and NiTi powder surface by homogeneous layer of Ti-oxide formed even during short exposure of the powder to the air.

  17. The Matthew effect in environmental science publication: A bibliometric analysis of chemical substances in journal articles

    Directory of Open Access Journals (Sweden)

    Grandjean Philippe

    2011-11-01

    Full Text Available Abstract Background While environmental research addresses scientific questions of possible societal relevance, it is unclear to what degree research focuses on environmental chemicals in need of documentation for risk assessment purposes. Methods In a bibliometric analysis, we used SciFinder to extract Chemical Abstract Service (CAS numbers for chemicals addressed by publications in the 78 major environmental science journals during 2000-2009. The Web of Science was used to conduct title searches to determine long-term trends for prominent substances and substances considered in need of research attention. Results The 119,636 journal articles found had 760,056 CAS number links during 2000-2009. The top-20 environmental chemicals consisted of metals, (chlorinated biphenyls, polyaromatic hydrocarbons, benzene, and ethanol and contributed 12% toward the total number of links- Each of the top-20 substances was covered by 2,000-10,000 articles during the decade. The numbers for the 10-year period were similar to the total numbers of pre-2000 articles on the same chemicals. However, substances considered a high priority from a regulatory viewpoint, due to lack of documentation, showed very low publication rates. The persistence in the scientific literature of the top-20 chemicals was only weakly related to their publication in journals with a high impact factor, but some substances achieved high citation rates. Conclusions The persistence of some environmental chemicals in the scientific literature may be due to a 'Matthew' principle of maintaining prominence for the very reason of having been well researched. Such bias detracts from the societal needs for documentation on less well known environmental hazards, and it may also impact negatively on the potentials for innovation and discovery in research.

  18. Global nutritional profiling for mutant and chemical mode-of-action analysis in filamentous fungi.

    Science.gov (United States)

    Tanzer, Matthew M; Arst, Herbert N; Skalchunes, Amy R; Coffin, Marie; Darveaux, Blaise A; Heiniger, Ryan W; Shuster, Jeffrey R

    2003-12-01

    We describe a method for gene function discovery and chemical mode-of-action analysis via nutrient utilization using a high throughput Nutritional Profiling platform suitable for filamentous microorganisms. We have optimized the growth conditions for each fungal species to produce reproducible optical density growth measurements in microtiter plates. We validated the Nutritional Profiling platform using a nitrogen source utilization assay to analyze 21 Aspergillus nidulans strains with mutations in the master nitrogen regulatory gene, areA. Analysis of these data accurately reproduced expected results and provided new data to demonstrate that this platform is suitable for fine level phenotyping of filamentous fungi. Next, we analyzed the differential responses of two fungal species to a glutamine synthetase inhibitor, illustrating chemical mode-of-action analysis. Finally, a comparative phenotypic study was performed to characterize carbon catabolite repression in four fungal species using a carbon source utilization assay. The results demonstrate differentiation between two Aspergillus species and two diverse plant pathogens and provide a wealth of new data on fungal nutrient utilization. Thus, these assays can be used for gene function and chemical mode-of-action analysis at the whole organism level as well as interspecies comparisons in a variety of filamentous fungi. Additionally, because uniform distribution of growth within wells is maintained, comparisons between yeast and filamentous forms of a single organism can be performed.

  19. Letters from China: A History of the Origins of the Chemical Analysis of Ceramics.

    Science.gov (United States)

    Pollard, A M

    2015-02-01

    This paper is an attempt to document the early history of the quantitative chemical analysis of ceramic materials in Europe, with a specific interest in the analysis of archaeological ceramics. This inevitably leads to a study of the attempts made in Europe to imitate the miraculous material--porcelain--imported from China from the fourteenth century onwards. It is clear that before the end of the eighteenth century progress was made in this endeavor by systematic but essentially trial-and-error firing of various raw materials, culminating in the successful production of European porcelain by Böttger and von Tschirnhaus in 1709. Shortly after this, letters describing the Chinese manufacture of porcelain, and, more importantly, samples of raw and fired material, began to arrive in Europe from French Jesuit missionaries, which were subjected to intense study. Following the perfection of gravimetric methods of chemical analysis in the late eighteenth century, these Chinese samples, and samples of porcelain from various European factories, were regularly analysed, particularly by Brongniart at Sèvres. Similar work was carried out on English porcelain by Simeon Shaw and Sir Arthur Church. The origins of the chemical analysis of archaeological ceramics are still somewhat obscure, but must date to the late eighteenth or early nineteenth centuries, by the likes of Vauquelin and Chaptal.

  20. USE OF AMAZONIAN SPECIES FOR AGING DISTILLED BEVERAGES: PHYSICAL AND CHEMICAL WOOD ANALYSIS

    Directory of Open Access Journals (Sweden)

    Jonnys Paz Castro

    2015-06-01

    Full Text Available The process of storing liquor in wooden barrels is a practice that aims to improve the sensory characteristics, such as color, aroma and flavor, of the beverage. The quality of the liquor stored in these barrels depends on wood characteristics such as density, permeability, chemical composition, anatomy, besides the wood heat treatment used to fabricate the barrels. Brazil has a great diversity of forests, mainly in the north, in the Amazon. This region is home to thousands of tree species, but is limited to the use of only a few native species to store liquors. The objective of this study was to determine some of the physical and chemical characteristics for four Amazon wood species. The results obtained in this study will be compared with others from woods that are traditionally used for liquor storage. The species studied were angelim-pedra (Hymenolobium petraeum Ducke cumarurana (Dipteryx polyphylla (Huber Ducke, jatobá (Hymenaea courbaril L. and louro-vermelho (Nectandra rubra (Mez CK Allen. The trees were collected from Precious Woods Amazon Company forest management area, in Silves, Amazonas. Analyzes such as: concentration of extractives, lignin amount, percentage of minerals (ash and tannin content, density, elemental analysis (CHNS-O and thermal analysis were done. It was observed that the chemical composition (lignin, holocellulose and elemental analysis (percentage of C, H, N and O of the woods have significant differences. The jatobá wood presented higher tannin content, and in the thermal analysis, was that which had the lowest mass loss.

  1. DPABI: Data Processing & Analysis for (Resting-State) Brain Imaging.

    Science.gov (United States)

    Yan, Chao-Gan; Wang, Xin-Di; Zuo, Xi-Nian; Zang, Yu-Feng

    2016-07-01

    Brain imaging efforts are being increasingly devoted to decode the functioning of the human brain. Among neuroimaging techniques, resting-state fMRI (R-fMRI) is currently expanding exponentially. Beyond the general neuroimaging analysis packages (e.g., SPM, AFNI and FSL), REST and DPARSF were developed to meet the increasing need of user-friendly toolboxes for R-fMRI data processing. To address recently identified methodological challenges of R-fMRI, we introduce the newly developed toolbox, DPABI, which was evolved from REST and DPARSF. DPABI incorporates recent research advances on head motion control and measurement standardization, thus allowing users to evaluate results using stringent control strategies. DPABI also emphasizes test-retest reliability and quality control of data processing. Furthermore, DPABI provides a user-friendly pipeline analysis toolkit for rat/monkey R-fMRI data analysis to reflect the rapid advances in animal imaging. In addition, DPABI includes preprocessing modules for task-based fMRI, voxel-based morphometry analysis, statistical analysis and results viewing. DPABI is designed to make data analysis require fewer manual operations, be less time-consuming, have a lower skill requirement, a smaller risk of inadvertent mistakes, and be more comparable across studies. We anticipate this open-source toolbox will assist novices and expert users alike and continue to support advancing R-fMRI methodology and its application to clinical translational studies.

  2. A multimedia environmental model of chemical distribution: fate, transport, and uncertainty analysis.

    Science.gov (United States)

    Luo, Yuzhou; Yang, Xiusheng

    2007-01-01

    This paper presented a framework for analysis of chemical concentration in the environment and evaluation of variance propagation within the model. This framework was illustrated through a case study of selected organic compounds of benzo[alpha]pyrene (BAP) and hexachlorobenzene (HCB) in the Great Lakes region. A multimedia environmental fate model was applied to perform stochastic simulations of chemical concentrations in various media. Both uncertainty in chemical properties and variability in hydrometeorological parameters were included in the Monte Carlo simulation, resulting in a distribution of concentrations in each medium. Parameters of compartmental dimensions, densities, emissions, and background concentrations were assumed to be constant in this study. The predicted concentrations in air, surface water and sediment were compared to reported data for validation purpose. Based on rank correlations, a sensitivity analysis was conducted to determine the influence of individual input parameters on the output variance for concentration in each environmental medium and for the basin-wide total mass inventory. Results of model validation indicated that the model predictions were in reasonable agreement with spatial distribution patterns, among the five lake basins, of reported data in the literature. For the chemical and environmental parameters given in this study, parameters associated to air-ground partitioning (such as moisture in surface soil, vapor pressure, and deposition velocity) and chemical distribution in soil solid (such as organic carbon partition coefficient and organic carbon content in root-zone soil) were targeted to reduce the uncertainty in basin-wide mass inventory. This results of sensitivity analysis in this study also indicated that the model sensitivity to an input parameter might be affected by the magnitudes of input parameters defined by the parameter settings in the simulation scenario. Therefore, uncertainty and sensitivity analyses

  3. Chemical and Physical Indicators in Drinking Water and Water Sources of Boroujerd Using Principal Components Analysis

    Directory of Open Access Journals (Sweden)

    Darabi , M. (MSC

    2014-05-01

    Full Text Available Background and Objective: Quality control of drinking water is important for maintaining health and safety of consumers, and the first step is to study the water quality variables. This study aimed to evaluate the chemical and physical indicators, water quality variables and qualitative classification of drinking water stations and water sources in Boroujerd. Material and Methods: This descriptive-cross sectional study was conducted on 70 samples of drinking water and 10 samples from sources in 2011-2012. Nine Water quality variables were measured and coded using STATISTICA10 Software. Principal component analysis (PCA was performed for qualitative classification of water samples and determination of water quality variables. Results: Based on PCA, chemical variables such as fluoride, nitrate, total hardness and iron, and physical variables such as pH and TDS were paramount importance to water quality. According to T-test, the average concentration of fluoride and iron, and the turbidity in all samples were significantly less than the standard. But other variables were up to standard. Conclusion: For the large water quality data, the use of PCA to identify the main qualitative variables and to classify physical and chemical variables can be used as an effective way in water quality management. Keywords: Physical and Chemical Indicators, Drinking Water and Sources, Boroujerd, Principal Component Analysis

  4. Phthalic Acid Chemical Probes Synthesized for Protein-Protein Interaction Analysis

    Directory of Open Access Journals (Sweden)

    Chin-Jen Wu

    2013-06-01

    Full Text Available Plasticizers are additives that are used to increase the flexibility of plastic during manufacturing. However, in injection molding processes, plasticizers cannot be generated with monomers because they can peel off from the plastics into the surrounding environment, water, or food, or become attached to skin. Among the various plasticizers that are used, 1,2-benzenedicarboxylic acid (phthalic acid is a typical precursor to generate phthalates. In addition, phthalic acid is a metabolite of diethylhexyl phthalate (DEHP. According to Gene_Ontology gene/protein database, phthalates can cause genital diseases, cardiotoxicity, hepatotoxicity, nephrotoxicity, etc. In this study, a silanized linker (3-aminopropyl triethoxyslane, APTES was deposited on silicon dioxides (SiO2 particles and phthalate chemical probes were manufactured from phthalic acid and APTES–SiO2. These probes could be used for detecting proteins that targeted phthalic acid and for protein-protein interactions. The phthalic acid chemical probes we produced were incubated with epithelioid cell lysates of normal rat kidney (NRK-52E cells to detect the interactions between phthalic acid and NRK-52E extracted proteins. These chemical probes interacted with a number of chaperones such as protein disulfide-isomerase A6, heat shock proteins, and Serpin H1. Ingenuity Pathways Analysis (IPA software showed that these chemical probes were a practical technique for protein-protein interaction analysis.

  5. Analysis of changes in the chemical composition of the blast furnace coke at high temperatures

    Directory of Open Access Journals (Sweden)

    A. Konstanciak

    2012-12-01

    Full Text Available Purpose: The main purpose of this paper was to analyze the behavior of coke in the blast furnace. The analysis of changes in chemical composition of coke due to impact of inert gas and air at different temperatures was made. The impact of the application of the thermoabrasion coefficient on the porosity of coke was also analyzed.Design/methodology/approach: By applying the Computer Thermochemical Database of the TERMO system (REAKTOR1 and REAKTOR3 three groups of substances can be distinguished. The chemical composition of blast furnace coke and the results of calculations of changes of chemical composition of coke heat treated under certain conditions were compared. The structural studies of these materials were presented.Findings: The results of the analysis of ash produced from one of Polish cokes was taken for consideration. This is not the average composition of Polish coke ashes, nevertheless it is representative of most commonly occurring chemical compositions.Practical implications: Thanks to the thermochemical calculations it is possible to predict ash composition after the treatment in a blast furnace. Those information was crucial and had an actual impact on determining the coke quality.Originality/value: Presentation of the analytical methods which, according to author, can be very useful to evaluate and identify the heat treatment for blast furnaces cokes. The research pursued represents part of a larger project carried out within the framework of Department Extraction and Recycling of Metals, Czestochowa University of Technology.

  6. Standardization of Cassia spectabilis with Respect to Authenticity, Assay and Chemical Constituent Analysis

    Directory of Open Access Journals (Sweden)

    Angeline Torey

    2010-05-01

    Full Text Available Quality control standardizations of the various medicinal plants used in traditional medicine is becoming more important today in view of the commercialization of formulations based on these plants. An attempt at standardization of Cassia spectabilis leaf has been carried out with respect to authenticity, assay and chemical constituent analysis. The authentication involved many parameters, including gross morphology, microscopy of the leaves and functional group analysis by Fourier Transform Infrared (FTIR spectroscopy. The assay part of standardization involved determination of the minimum inhibitory concentration (MIC of the extract which could help assess the chemical effects and establish curative values. The MIC of the C. spectabilis leaf extracts was investigated using the Broth Dilution Method. The extracts showed a MIC value of 6.25 mg/mL, independent of the extraction time. The chemical constituent aspect of standardization involves quantification of the main chemical components in C. spectabilis. The GCMS method used for quantification of 2,4-(1H,3H-pyrimidinedione in the extract was rapid, accurate, precise, linear (R2 = 0.8685, rugged and robust. Hence this method was suitable for quantification of this component in C. spectabilis. The standardization of C. spectabilis is needed to facilitate marketing of medicinal plants, with a view to promoting the export of valuable Malaysian Traditional Medicinal plants such as C. spectabilis.

  7. Analysis of pharmaceutical pellets: An approach using near-infrared chemical imaging

    Energy Technology Data Exchange (ETDEWEB)

    Sabin, Guilherme P.; Breitkreitz, Marcia C.; Souza, Andre M. de [Institute of Chemistry, University of Campinas, P.O. Box 6154, 13084-971 Campinas, SP (Brazil); Fonseca, Patricia da; Calefe, Lupercio; Moffa, Mario [Zelus Servicos para Industria Farmaceutica Ltda., Av. Professor Lineu Prestes n. 2242, Sao Paulo, SP (Brazil); Poppi, Ronei J., E-mail: ronei@iqm.unicamp.br [Institute of Chemistry, University of Campinas, P.O. Box 6154, 13084-971 Campinas, SP (Brazil)

    2011-11-07

    Highlights: {yields} Near-Infrared Chemical Imaging was used for pellets analysis. {yields} Distribution of the components throughout the coatings layers and core of the pellets was estimated. {yields} Classical Least Squares (CLS) was used for calculation of the concentration maps. - Abstract: Pharmaceutical pellets are spherical or nearly spherical multi-unit dosage forms designed to optimize pharmacokinetics and pharmacodynamics features of drug release. The distribution of the pharmaceutical ingredients in the layers and core is a very important parameter for appropriate drug release, especially for pellets manufactured by the process of layer gain. Physical aspects of the sample are normally evaluated by Scanning Electron Microscopy (SEM), but it is in many cases unsuitable to provide conclusive chemical information about the distribution of the pharmaceutical ingredients in both layers and core. On the other hand, methods based on spectroscopic imaging can be very promising for this purpose. In this work, a Near-Infrared Chemical Imaging (NIR-CI) method was developed and applied to the analysis of diclophenac sodium pellets. Since all the compounds present in the sample were known in advance, Classical Least Squares (CLS) was used for calculations. The results have shown that the method was capable of providing chemical information about the distribution of the active ingredient and excipients in the core and coating layers and therefore can be complementary to SEM for the pharmaceutical development of pellets.

  8. Translated chemical reaction networks.

    Science.gov (United States)

    Johnston, Matthew D

    2014-05-01

    Many biochemical and industrial applications involve complicated networks of simultaneously occurring chemical reactions. Under the assumption of mass action kinetics, the dynamics of these chemical reaction networks are governed by systems of polynomial ordinary differential equations. The steady states of these mass action systems have been analyzed via a variety of techniques, including stoichiometric network analysis, deficiency theory, and algebraic techniques (e.g., Gröbner bases). In this paper, we present a novel method for characterizing the steady states of mass action systems. Our method explicitly links a network's capacity to permit a particular class of steady states, called toric steady states, to topological properties of a generalized network called a translated chemical reaction network. These networks share their reaction vectors with their source network but are permitted to have different complex stoichiometries and different network topologies. We apply the results to examples drawn from the biochemical literature.

  9. Size and functional tuning of solid state nanopores by chemical functionalization

    Science.gov (United States)

    Mussi, Valentina; Fanzio, Paola; Firpo, Giuseppe; Repetto, Luca; Valbusa, Ugo

    2012-11-01

    We demonstrate the possibility of using a simple functionalization procedure, based on an initial vapour-phase silanization, to control the size and functionality of solid state nanopores. The presented results show that, by varying the silanization time, it is possible to modify the efficiency of probe molecule attachment, thus shrinking the pore to the chosen size, while introducing a specific sensing selectivity. The proposed method allows us to tune the nanopore biosensor adapting it to the specific final application, and it can be efficiently applied when the pore initial diameter does not exceed a limit dimension related to the mean free path of the silane molecules at the working pressure.

  10. Chemical Dynamics of State-Selected Atomic and Diatomic Ions of Aerospace Relevance

    Science.gov (United States)

    2008-11-01

    modified the triple - quadrupole -double-octopole y<t&te Cy» LJMW • • Figure 1. Schematic diagram of the comprehensive VUV laser system, which...H. Xu, and C. Y. Ng, "The Study of State-Selected Ion-Molecule Reactions using the Pulsed-Field Ionization- Photoion Technique ", J. Chem. Phys...8217==0-4) + He collisions in the ET range of 0-3 eV have also been measured using the VUV-photoionization-guided-ion beam mass spectrometric technique

  11. Chemical composition of Thymus vulgaris L. (thyme essential oil from the Rio de Janeiro State (Brazil

    Directory of Open Access Journals (Sweden)

    ALEXANDRE PORTE

    2008-03-01

    Full Text Available The essential oil from fresh leaves of Thymus vulgaris L. from Rio de Janeiro State, Brazil, was isolated by hydrodistillation and analyzed through a combination of GC and GC/MS. Compounds representing 95.1 % of the oil were identified. Thirty-nine constituents were detected, of which twenty-eight were identified according to their chromatographic retention indices and mass spectra. The major constituents of the oil were thymol (44.7 %, p-cymene (18.6 % and g-terpinene (16.5 %.

  12. Complex network analysis of state spaces for random Boolean networks

    Energy Technology Data Exchange (ETDEWEB)

    Shreim, Amer [Complexity Science Group, Department of Physics and Astronomy, University of Calgary, Calgary, AB, T2N 1N4 (Canada); Berdahl, Andrew [Complexity Science Group, Department of Physics and Astronomy, University of Calgary, Calgary, AB, T2N 1N4 (Canada); Sood, Vishal [Complexity Science Group, Department of Physics and Astronomy, University of Calgary, Calgary, AB, T2N 1N4 (Canada); Grassberger, Peter [Complexity Science Group, Department of Physics and Astronomy, University of Calgary, Calgary, AB, T2N 1N4 (Canada); Paczuski, Maya [Complexity Science Group, Department of Physics and Astronomy, University of Calgary, Calgary, AB, T2N 1N4 (Canada)

    2008-01-15

    We apply complex network analysis to the state spaces of random Boolean networks (RBNs). An RBN contains N Boolean elements each with K inputs. A directed state space network (SSN) is constructed by linking each dynamical state, represented as a node, to its temporal successor. We study the heterogeneity of these SSNs at both local and global scales, as well as sample to-sample fluctuations within an ensemble of SSNs. We use in-degrees of nodes as a local topological measure, and the path diversity (Shreim A et al 2007 Phys. Rev. Lett. 98 198701) of an SSN as a global topological measure. RBNs with 2 {<=} K {<=} 5 exhibit non-trivial fluctuations at both local and global scales, while K = 2 exhibits the largest sample-to-sample (possibly non-self-averaging) fluctuations. We interpret the observed 'multi scale' fluctuations in the SSNs as indicative of the criticality and complexity of K = 2 RBNs. 'Garden of Eden' (GoE) states are nodes on an SSN that have in-degree zero. While in-degrees of non-GoE nodes for K > 1 SSNs can assume any integer value between 0 and 2{sup N}, for K = 1 all the non-GoE nodes in a given SSN have the same in-degree which is always a power of two.

  13. Chemical analysis of fish bile extracts for monitoring endocrine disrupting chemical exposure in water: Bisphenol A, alkylphenols, and norethindrone.

    Science.gov (United States)

    Wu, Minghong; Pan, Chenyuan; Yang, Ming; Xu, Bentuo; Lei, Xiangjie; Ma, Jing; Cai, Ling; Chen, Jingsi

    2016-01-01

    The present study determined concentrations of estrogenic bisphenol A (BPA), nonylphenol, octylphenol (4-tert-octylphenol), butylphenol (4-tert-butylphenol), and progestogenic norethindrone by liquid chromatography-tandem mass spectrometry in bile extracts from field fish from the Xin'an River and market fish in Shanghai, China. Compared with the field fish, endocrine disrupting chemical (EDC) concentrations in market fish bile were at relatively high levels with high detectable rates. The average concentrations of BPA, nonylphenol, 4-tert-octylphenol, 4-tert-butylphenol, and norethindrone in field fish bile were 30.1 µg/L, 203 µg/L, 4.69 µg/L, 7.84 µg/L, and 0.514 µg/L, respectively; in market fish bile they were 240 µg/L, 528 µg/L, 76.5 µg/L, 12.8 µg/L, and 5.26 µg/L, respectively; and in the surface water of Xin'an River they were 38.8 ng/L, 7.91 ng/L, 1.98 ng/L, 2.66 ng/L, and 0.116 ng/L, respectively. The average of total estrogenic activity of river water was 3.32 ng/L estradiol equivalents. High bioconcentration factors (BCFs) were discovered for all 5 EDCs (≧998-fold) in field fish bile. Furthermore, the authors analyzed the BCF value of BPA in fish bile after 30-d exposure to environmentally relevant concentrations of BPA in the laboratory, and the analysis revealed that BCF in fish bile (BCF(Fish bile)) changed in an inverse concentration-dependent manner based on the log10-transformed BPA concentration in water. Strikingly, the data from the field study were well fitted within this trend. The data together suggested that analysis of fish bile extracts could be an efficient method for assessing waterborne EDCs exposure for aquatic biota.

  14. Laser Induced Breakdown Spectroscopy applications to meteorites: Chemical analysis and composition profiles

    Science.gov (United States)

    Dell'Aglio, M.; De Giacomo, A.; Gaudiuso, R.; Pascale, O. De; Senesi, G. S.; Longo, S.

    2010-12-01

    A fast procedure for chemical analysis of different meteorites is presented, based on LIBS (Laser Induced Breakdown Spectroscopy). The technique is applied to several test cases (Dhofar 019, Dhofar 461, Sahara 98222, Toluca, Sikhote Alin and Campo del Cielo) and can be useful for rapid meteorite identification providing geologists with specific chemical information for meteorite classification. Concentration profiles of Fe, Ni and Co are simultaneously detected across the Widmanstätten structure of the iron meteorite Toluca with a view to determining cooling rates. The LIBS analysis of meteorites is also used as a laboratory test for analogous studies on the respective parent bodies (Mars, asteroids) in space exploration missions where one clear advantage of the proposed technique is that no direct contact with the sample is required.

  15. HRI catalytic two-stage liquefaction (CTSL) process materials: chemical analysis and biological testing

    Energy Technology Data Exchange (ETDEWEB)

    Wright, C.W.; Later, D.W.

    1985-12-01

    This report presents data from the chemical analysis and biological testing of coal liquefaction materials obtained from the Hydrocarbon Research, Incorporated (HRI) catalytic two-stage liquefaction (CTSL) process. Materials from both an experimental run and a 25-day demonstration run were analyzed. Chemical methods of analysis included adsorption column chromatography, high-resolution gas chromatography, gas chromatography/mass spectrometry, low-voltage probe-inlet mass spectrometry, and proton nuclear magnetic resonance spectroscopy. The biological activity was evaluated using the standard microbial mutagenicity assay and an initiation/promotion assay for mouse-skin tumorigenicity. Where applicable, the results obtained from the analyses of the CTSL materials have been compared to those obtained from the integrated and nonintegrated two-stage coal liquefaction processes. 18 refs., 26 figs., 22 tabs.

  16. Metal-assisted chemical etching of CIGS thin films for grain size analysis

    Energy Technology Data Exchange (ETDEWEB)

    Xue, Chaowei [Research and Development Centre, Hanergy Thin Film Power Group Limited, Chengdu (China); Loi, Huu-Ha; Duong, Anh; Parker, Magdalena [Failure Analysis Department, MiaSole Hi-Tech Corp., Santa Clara, CA (United States)

    2016-09-15

    Grain size of the CIGS absorber is an important monitoring factor in the CIGS solar cell manufacturing. Electron backscatter diffraction (EBSD) analysis is commonly used to perform CIGS grain size analysis in the scanning electron microscope (SEM). Although direct quantification on SEM image using the average grain intercept (AGI) method is faster and simpler than EBSD, it is hardly applicable on CIGS thin films. The challenge is that, not like polycrystalline silicon, to define grain boundaries by selective chemical etching is not easily realizable for the multi-component CIGS alloy. In this Letter, we present direct quantification of CIGS thin film grain size using the AGI method by developing metal-assisted wet chemical etching process to define CIGS grain boundaries. The calculated value is similar to EBSD result. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  17. GRAPHICAL ANALYSIS OF LAFFER'S THEORY FOR EUROPEAN UNION MEMBER STATES

    Directory of Open Access Journals (Sweden)

    LILIANA BUNESCU

    2013-04-01

    Full Text Available Most times the current situation of one or another country depends on the historical development of own tax system. A practical question of any governance is to determine the optimal taxation rate level, bringing to the state the highest tax revenues. A good place to start is with what is popularly known as the Laffer curve. This paper aims to determine in graphical terms the level where European economies ranks by using Laffer curve based on the data series provided by the European Commission and the World Bank. Graphical analysis of Laffer's theory can emphasize only the positioning on one or another side of point for maximum tax revenues, a position that can influence fiscal policy decisions. Conclusions at European Union level are simple. Value of taxation rate for fiscal optimal point varies from one Member State to another, from 48.9% in Denmark to 28% in Romania, with an average of 37.1% for the EU-27.

  18. Equation of state for steam for systems analysis

    Energy Technology Data Exchange (ETDEWEB)

    Muneer, T.

    1985-01-01

    For engineers involved in the analysis of thermal systems, it may be desirable to compute thermodynamic properties using an equation of state rather than tables or charts. In this work, a pressure explicit equation of state for steam is developed by curve fitting of P-V-T data. An efficient optimization method was used for the least-squares minimization. The five-constant, Beattie-Bridgeman equation developed here was found to perform well in computation of a property when the other two were provided. The equation is inherently simple in form, and therefore, computation of other thermodynamic properties such as enthalpy and entropy will be an easy matter. Thus, the equation will be invaluable in design and optimization of steam-based thermal systems.

  19. Study of the interrelationships among chemical and petrographic variables of United States coals

    Energy Technology Data Exchange (ETDEWEB)

    Waddell, C.; Davis, A.; Spackman, W.; Griffiths, J. C.

    1978-03-01

    Multivariate statistical techniques are used in a study of the interrelationships among various coal properties. The properties chosen for study are the components of the ultimate analysis (carbon, hydrogen, organic sulfur, nitrogen and oxygen); moisture; volatile matter; calorific value; maximum reflectance of the vitrinite-group macerals; and the relative proportions of the vitrinite-, liptinite-, and inertinite-group macerals. The coals included in the study are from four coal provinces (Eastern, Interior, Rocky Mountain, and Northern Great Plains) and range in rank from lignite to anthracite. A coal's characteristics, properties, and utilization behavior are determined by the maceral and mineral materials composing the coal. The level of coalification achieved by the maceral materials is of critical importance in fixing the properties. A factor analysis performed on all data together indicates that most variation in the data set is correlated with changes in rank (variables which vary with rank include carbon, oxygen, calorific value, moisture, volatile matter, and reflectance). The maceral groups account for the next greatest amount of variation. Nitrogen and sulfur are each independent of all other variables. A cluster analysis indicates that the data set represents a continuum with no distinct groups; however, the data set may be dissected into four groups distinguished from each other on the basis of rank, on the relative proportions of the maceral groups, and on the organic sulfur content. Factor analyses of the individual groups provide insights into coalification at various stages of rank.

  20. Decomposition analysis of green chemical technology inventions from 1971 to 2010 in Japan

    OpenAIRE

    Fujii, Hidemichi; Shirakawa, Seiji

    2015-01-01

    Green chemistry plays an important role in achieving sustainable development. This study examines the determinant factors for technology invention related to green chemistry in Japan using patent application data and a decomposition analysis framework. Our main findings are that the number of green chemical technologies applied to production processes have increased because of the scale-up of overall research activities and increased priority. Additionally, the number of patent applications f...

  1. Chemical composition analysis of raw materials used in iron ore sinter plants in Poland

    Directory of Open Access Journals (Sweden)

    D. Burchart-Korol

    2014-07-01

    Full Text Available The main goal of the study was the analysis of the chemical compositions of raw materials used in iron ore sinter plants in Poland. The iron ore sintering process is the largest source of emissions of dust and gas pollution in the iron and steel industry. Hematite ores, magnetite concentrates, admixtures (dolomite, limestone and burnt lime, fuels (coke breeze, anthracite and by-products are used in Poland to produce the sinter mixture.

  2. Principles of ESCA and applications to metal corrosion, coating and lubrication. [Electron Spectroscopy for Chemical Analysis

    Science.gov (United States)

    Wheeler, D. R.

    1978-01-01

    The principles of ESCA (electron spectroscopy for chemical analysis) are described by comparison with other spectroscopic techniques. The advantages and disadvantages of ESCA as compared to other surface sensitive analytical techniques are evaluated. The use of ESCA is illustrated by actual applications to oxidation of steel and Rene 41, the chemistry of lubricant additives on steel, and the composition of sputter deposited hard coatings. Finally, a bibliography of material that is useful for further study of ESCA is presented and commented upon.

  3. Enhancing the chemical mixture methodology in emergency preparedness and consequence assessment analysis.

    Science.gov (United States)

    Yu, Xiao-Ying; Glantz, Clifford S; Yao, Juan; He, Hua; Petrocchi, Achille J; Craig, Douglas K; Ciolek, John T; Booth, Alexander E

    2013-11-16

    Emergency preparedness personnel at U.S. Department of Energy (DOE) facilities use the chemical mixture methodology (CMM) to estimate the potential health impacts to workers and the public from the unintended airborne release of chemical mixtures. The CMM uses a Hazard Index (HI) for each chemical in a mixture to compare a chemical's concentration at a receptor location to an appropriate concentration limit for that chemical. This limit is typically based on Protection Action Criteria (PAC) values developed and published by the DOE. As a first cut, the CMM sums the HIs for all the chemicals in a mixture to conservatively estimate their combined health impact. A cumulative HI>1.0 represents a concentration exceeding the concentration limit and indicates the potential for adverse health effects. Next, Health Code Numbers (HCNs) are used to identify the target organ systems that may be impacted by exposure to each chemical in a mixture. The sum of the HIs for the maximally impacted target organ system is used to provide a refined, though still conservative, estimate of the potential for adverse health effects from exposure to the chemical mixture. This paper explores approaches to enhance the effectiveness of the CMM by using HCN weighting factors. A series of 24 case studies have been defined to evaluate both the existing CMM and three new approaches for improving the CMM. The first approach uses a set of HCN weighting factors that are applied based on the priority ranking of the HCNs for each chemical. The second approach uses weighting factors based on the priority rankings of the HCNs established for a given type of concentration limit. The third approach uses weighting factors that are based on the exposure route used to derive PAC values and a priority ranking of the HCNs (the same ranking as used in the second approach). Initial testing indicates that applying weighting factors increases the effectiveness of the CMM in general, though care must be taken to

  4. Chemical degradation of proteins in the solid state with a focus on photochemical reactions.

    Science.gov (United States)

    Mozziconacci, Olivier; Schöneich, Christian

    2015-10-01

    Protein pharmaceuticals comprise an increasing fraction of marketed products but the limited solution stability of proteins requires considerable research effort to prepare stable formulations. An alternative is solid formulation, as proteins in the solid state are thermodynamically less susceptible to degradation. Nevertheless, within the time of storage a large panel of kinetically controlled degradation reactions can occur such as, e.g., hydrolysis reactions, the formation of diketopiperazine, condensation and aggregation reactions. These mechanisms of degradation in protein solids are relatively well covered by the literature. Considerably less is known about oxidative and photochemical reactions of solid proteins. This review will provide an overview over photolytic and non-photolytic degradation reactions, and specially emphasize mechanistic details on how solid structure may affect the interaction of protein solids with light.

  5. Positronium in a Liquid Phase: Formation, Bubble State and Chemical Reactions

    Directory of Open Access Journals (Sweden)

    Sergey V. Stepanov

    2012-01-01

    Full Text Available The present approach describes the e+ fate since its injection into a liquid until its annihilation. Several stages of the e+ evolution are discussed: (1 energy deposition and track structure of fast positrons: ionization slowing down, number of ion-electron pairs, typical sizes, thermalization, electrostatic interaction between e+ and the constituents of its blob, and effect of local heating; (2 positronium formation in condensed media: the Ore model, quasifree Ps state, intratrack mechanism of Ps formation; (3 fast intratrack diffusion-controlled reactions: Ps oxidation and ortho-paraconversion by radiolytic products, reaction rate constants, and interpretation of the PAL spectra in water at different temperatures; (4 Ps bubble models. Inner structure of positronium (wave function, energy contributions, relationship between the pick-off annihilation rate and the bubble radius.

  6. Measurements of the aerosol chemical composition and mixing state in the Po Valley using multiple spectroscopic techniques

    Science.gov (United States)

    Decesari, S.; Allan, J.; Plass-Duelmer, C.; Williams, B. J.; Paglione, M.; Facchini, M. C.; O'Dowd, C.; Harrison, R. M.; Gietl, J. K.; Coe, H.; Giulianelli, L.; Gobbi, G. P.; Lanconelli, C.; Carbone, C.; Worsnop, D.; Lambe, A. T.; Ahern, A. T.; Moretti, F.; Tagliavini, E.; Elste, T.; Gilge, S.; Zhang, Y.; Dall'Osto, M.

    2014-11-01

    The use of co-located multiple spectroscopic techniques can provide detailed information on the atmospheric processes regulating aerosol chemical composition and mixing state. So far, field campaigns heavily equipped with aerosol mass spectrometers have been carried out mainly in large conurbations and in areas directly affected by their outflow, whereas lesser efforts have been dedicated to continental areas characterised by a less dense urbanisation. We present here the results obtained at a background site in the Po Valley, Italy, in summer 2009. For the first time in Europe, six state-of-the-art spectrometric techniques were used in parallel: aerosol time-of-flight mass spectrometer (ATOFMS), two aerosol mass spectrometers (high-resolution time-of-flight aerosol mass spectrometer - HR-ToF-AMS and soot particle aerosol mass spectrometer - SP-AMS), thermal desorption aerosol gas chromatography (TAG), chemical ionisation mass spectrometry (CIMS) and (offline) proton nuclear magnetic resonance (1H-NMR) spectroscopy. The results indicate that, under high-pressure conditions, atmospheric stratification at night and early morning hours led to the accumulation of aerosols produced by anthropogenic sources distributed over the Po Valley plain. Such aerosols include primary components such as black carbon (BC), secondary semivolatile compounds such as ammonium nitrate and amines and a class of monocarboxylic acids which correspond to the AMS cooking organic aerosol (COA) already identified in urban areas. In daytime, the entrainment of aged air masses in the mixing layer is responsible for the accumulation of low-volatility oxygenated organic aerosol (LV-OOA) and also for the recycling of non-volatile primary species such as black carbon. According to organic aerosol source apportionment, anthropogenic aerosols accumulating in the lower layers overnight accounted for 38% of organic aerosol mass on average, another 21% was accounted for by aerosols recirculated in

  7. Chemical abundance analysis of symbiotic giants. RW Hya, SY Mus, BX Mon, and AE Ara

    CERN Document Server

    Galan, Cezary; Hinkle, Kenneth H; Schmidt, Miroslaw R; Gromadzki, Mariusz

    2014-01-01

    Symbiotic stars are the long period, binary systems of strongly interacting stars at the final stages of evolution which can be useful tool to understand the chemical evolution of the Galaxy and the formation of stellar populations. Knowledge of the chemical composition of the symbiotic giants is essential to advancing our understanding of these issues but unfortunately reliably determinations exist only in a few cases. We perform a program for detailed chemical composition analysis in over 30 symbiotic giants, based on the high resolution, near-IR spectra, obtained with Phoenix/Gemini South spectrometer. The methods of the standard LTE analysis is used to obtain photospheric abundances of CNO and elements around iron peak. Here we present results obtained for four objects: RW Hya, SY Mus, BX Mon, and AE Ara. Our analysis revealed a significantly sub-solar metallicity (Me/H ~ -0.75) for RW Hya, a slightly sub-solar metallicities (Me/H ~ 0.2-0.3) in BX Mon and AE Ara, and a near-solar metallicity in SY Mus. 12...

  8. Prediction of the Chapman-Jouguet chemical equilibrium state in a detonation wave from first principles based reactive molecular dynamics.

    Science.gov (United States)

    Guo, Dezhou; Zybin, Sergey V; An, Qi; Goddard, William A; Huang, Fenglei

    2016-01-21

    The combustion or detonation of reacting materials at high temperature and pressure can be characterized by the Chapman-Jouguet (CJ) state that describes the chemical equilibrium of the products at the end of the reaction zone of the detonation wave for sustained detonation. This provides the critical properties and product kinetics for input to macroscale continuum simulations of energetic materials. We propose the ReaxFF Reactive Dynamics to CJ point protocol (Rx2CJ) for predicting the CJ state parameters, providing the means to predict the performance of new materials prior to synthesis and characterization, allowing the simulation based design to be done in silico. Our Rx2CJ method is based on atomistic reactive molecular dynamics (RMD) using the QM-derived ReaxFF force field. We validate this method here by predicting the CJ point and detonation products for three typical energetic materials. We find good agreement between the predicted and experimental detonation velocities, indicating that this method can reliably predict the CJ state using modest levels of computation.

  9. Stochastic Analysis of Land Degradation on Edo State Agricultural System

    Directory of Open Access Journals (Sweden)

    Olotu Yahaya

    2014-07-01

    Full Text Available Edo state, like many other states in Niger-Delta and Nigeria as a nation has resultant land and water degradation problems such as persistent oil spillage, erosion of arable land, sedimentation of dam and reservoirs. This research study investigates the effects of land degradation in all the local government areas in Edo state. The results of the findings indicated that 28% corresponding to 634,416.3 ha of arable land had totally been affected by soil erosion. Highest erodibility index of 0.75 was obtained at Estako west (Auchi, while least value of 0.1 was found at Akoko-Edo local government area respectively. Between 1976 and 1997, 1,820,410.50 barrels of crude oil spilled with maximum spill value 600,511.02 barrels in 1984 and minimum spill of 5,956 barrels in 1989. Reduction of cassava production was estimated and analyzed. The result showed that the reduction is highly significant at 95% confidence interval. Etasko -west had the highest reduction from 7.26 MT/HA in 1993 to 1.1 MT/HA in 2002. In addition, analysis of erosion and land degradation control expenditures showed that little attention has been paid to controlling land degradation in the state. Erosion control expenditure was increased from 4.1% in 1990 to 10% in 2002. This increase is not significant at 0.01 and 0.05 levels of significance. All these constraints affect agricultural production, human well-being, social and economic growth of the people in Edo state.

  10. Meta-analysis of mass balances examining chemical fate during wastewater treatment.

    Science.gov (United States)

    Heidler, Jochen; Halden, Rolf U

    2008-09-01

    Mass balances are an instructive means for investigating the fate of chemicals during wastewater treatment. In addition to the aqueous-phase removal efficiency (phi), they can inform on chemical partitioning, transformation, and persistence, as well as on the chemical loading to streams and soils receiving, respectively, treated effluent and digested sewage sludge (biosolids). Release rates computed on a per-capita basis can serve to extrapolate findings to a larger scale. This review examines over a dozen mass balances conducted for various organic wastewater contaminants, including prescription drugs, estrogens, fragrances, antimicrobials, and surfactants of differing sorption potential (hydrophobicity), here expressed as the 1-octanol-water partition coefficient (K(OW)) and the organic carbon normalized sorption coefficient (K(OC)). Major challengesto mass balances are the collection of representative samples and accurate quantification of chemicals in sludge. A meta-analysis of peer-reviewed data identified sorption potential as the principal determinant governing chemical persistence in biosolids. Occurrence data for organic wastewater compounds detected in digested sludge followed a simple nonlinear model that required only K(OW) or K(OC) as the input and yielded a correlation coefficient of 0.9 in both instances. The model predicted persistence in biosolids for the majority (> 50%) of the input load of organic wastewater compounds featuring a log10 K(OW) value of greater than 5.2 (log10 K(OC) > 4.4). In contrast, hydrophobicity had no or only limited value for estimating, respectively, phi and the overall persistence of a chemical during conventional wastewater treatment.

  11. Analysis on the Current Status of Chemical Decontamination Technology of Steam Generators in the Oversea Nuclear Power Plants (NPPs)

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, Taebin; Kim, Sukhoon; Kim, Juyoul; Kim, Juyub; Lee, Seunghee [FNC Technology Co. Ltd., Yongin (Korea, Republic of)

    2015-10-15

    The steam generators in Hanbit Unit 3 and 4 are scheduled to be replaced in 2018 and 2019, respectively. Nevertheless, the wastes from the dismantled steam generators are currently just on-site stored in the NPP because there are no disposal measures for the waste and lack of the decontamination techniques for large-sized metallic equipment. In contrast, in the oversea NPPs, there are many practical cases of chemical decontamination not only for oversized components in the NPPs such as reactor pressure vessel and steam generator, but also for major pipes. Chemical decontamination technique is more effective in decontaminating the components with complicated shape compared with mechanical one. Moreover, a high decontamination factor can be obtained by using strong solvent, and thereby most of radionuclides can be removed. Due to these advantages, the chemical decontamination has been used most frequently for operation of decontaminating the large-sized equipment. In this study, an analysis on the current status of chemical decontamination technique used for the steam generators of the foreign commercial NPPs was performed. In this study, the three major chemical decontamination processes were reviewed, which are applied to the decommissioning process of the steam generators in the commercial NPPs of the United States, Germany, and Belgium. The three processes have the different features in aspect of solvent, while those are based in common on the oxidation and reduction between the target metal surface and solvents. In addition, they have the same goals for improving the decontamination efficiency and decreasing the amount of the secondary waste generation. Based on the analysis results on component sub-processes and major advantages and disadvantages of each process, Table 2 shows the key fundamental technologies for decontamination of the steam generator in Korea and the major considerations in the development process of each technology. It is necessary to prepare

  12. The proposed Diagnostic Instrumentation and Analysis Laboratory, Mississippi State University

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1994-11-01

    The Department of Energy (DOE) proposes to authorize Mississippi State University (MSU) to proceed with the detailed design, construction and equipping of the proposed Diagnostic Instrumentation and Analysis Laboratory (DIAL). DOE grant funds are available to the University for the limited purpose of performing preliminary studies, including analysis necessary to conduct this environmental assessment. The proposed facility would be located in the Mississippi Research and Technology Park, adjacent to the Mississippi Agriculture and Forestry Experiment Station campus in Starkville, Mississippi. Total project cost is estimated at $7,953,600. This proposed laboratory would be designed to conduct research into combustion devices related to waste management and environmental restoration that is of importance to industry and government. The proposed facility`s role would be to develop diagnostic instrumentation capabilities in the area of combustion and related processes.

  13. Growth control, structure, chemical state, and photoresponse of CuO-CdS core-shell heterostructure nanowires.

    Science.gov (United States)

    El Mel, A A; Buffière, M; Bouts, N; Gautron, E; Tessier, P Y; Henzler, K; Guttmann, P; Konstantinidis, S; Bittencourt, C; Snyders, R

    2013-07-05

    The growth of single-crystal CuO nanowires by thermal annealing of copper thin films in air is studied. We show that the density, length, and diameter of the nanowires can be controlled by tuning the morphology and structure of the copper thin films deposited by DC magnetron sputtering. After identifying the optimal conditions for the growth of CuO nanowires, chemical bath deposition is employed to coat the CuO nanowires with CdS in order to form p-n nanojunction arrays. As revealed by high-resolution TEM analysis, the thickness of the polycrystalline CdS shell increases when decreasing the diameter of the CuO core for a given time of CdS deposition. Near-edge x-ray absorption fine-structure spectroscopy combined with transmission x-ray microscopy allows the chemical analysis of isolated nanowires. The absence of modification in the spectra at the Cu L and O K edges after the deposition of CdS on the CuO nanowires indicates that neither Cd nor S diffuse into the CuO phase. We further demonstrate that the core-shell nanowires exhibit the I-V characteristic of a resistor instead of a diode. The electrical behavior of the device was found to be photosensitive, since increasing the incident light intensity induces an increase in the collected electrical current.

  14. Chemical, colloidal and mechanical contributions to the state of water in wood cell walls

    Science.gov (United States)

    Bertinetti, L.; Fratzl, P.; Zemb, T.

    2016-08-01

    The properties of wood depend strongly on its water content, but the physicochemical basis for the interaction of water with cell wall components is poorly understood. Due to the importance of the problem both in the context of wood technology and the biological function of swelling and dehydration for growth stresses and seed dispersal, a wealth of descriptive data has been accumulated but a microscopic theory of water-biomolecular interactions is missing. We develop here, at a primitive level, a minimal parameter-free, coarse-grained, model of wood secondary cell walls to predict water absorption, in the form of an equation of state. It includes for the first time all three—mechanical, colloidal and chemical—contributions, taking into account the cell walls microstructure. The hydration force around the elongated cellulose crystals and entropy of mixing of the matrix polymers (hemicelluloses and lignin) are the dominant contributions driving the swelling. The elastic energy needed to swell the composite is the main term opposing water uptake. Hysteresis is not predicted but water uptake versus humidity, is reproduced in a large temperature range. Within this framework, the origin of wood dissolution and different effects of wood treatments on water sorption can be understood at the molecular level.

  15. New Patterns in Steady-State Chemical Kinetics: Intersections, Coincidences, Map of Events (Two-Step Mechanism

    Directory of Open Access Journals (Sweden)

    Daniel Branco Pinto

    2015-10-01

    Full Text Available New patterns of steady-state chemical kinetics for continuously stirred-tank reactors (CSTR have been found, i.e., intersections, maxima and coincidences, for two-step mechanism A↔B→C. There were found elegant analytical relationships for characteristics of these patterns (space times, values of concentrations and rates allowing kinetic parameters to be easily determined. It was demonstrated that for the pair of species involved into the irreversible reaction (B and C, the space time of their corresponding concentration dependence intersection is invariant and does not depend on the initial conditions of the system. Maps of patterns are presented for visualization of their combinations and ranking in space time, and values of concentration and rates.

  16. Unconditionally stable, second-order accurate schemes for solid state phase transformations driven by mechano-chemical spinodal decomposition

    CERN Document Server

    Sagiyama, Koki; Garikipati, Krishna

    2015-01-01

    We consider solid state phase transformations that are caused by free energy densities with domains of non-convexity in strain-composition space. We refer to the non-convex domains as mechano-chemical spinodals. The non-convexity with respect to composition causes segregation into phases with different crystal structures. If, for one of these crystal structures, the free energy density is also non-convex with respect to strain, there is potential for the corresponding phase to further separate into multiple variants. For mathematical well-posedness the free energy description must be enhanced by interface terms that penalize gradients with respect to strain and composition. A system of PDEs results that couples the classical Cahn-Hilliard equation with those of gradient elasticity. Since the materials systems of interest display finite strains, the appropriate description is Toupin's theory of gradient elasticity at finite strains. The presence of strain and composition gradients in the free energy density le...

  17. Quasi-solid state dye-sensitized solar cells based on pyridine or imidazole containing copolymer chemically crosslinked gel electrolytes

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Quasi-solid state dye-sensitized solar cells based on chemically crosslinking with backbone polymers of poly(vinylpyridine-co-acrylonitrile) (P(VP-co-AN)) or poly(vinylimidazole-co-acrylonitrile) (P(VIM-co- AN)) and diiodide compounds of I(CH2)6I or I(CH2CH2O)nCH2CH2I solidified EC/PC/KI/I2 gel electrolytes have been fabricated. The ionic conductivities and apparent diffusion coefficients of I3-Of the electrolytes and cell performances have been investigated. Providing chemically crosslinking points, pyridine or imidazole from the backbone polymers benefited the open circuit voltage and fill factor of the cells. Consequently, the overall energy conversion efficiencies of the quasi-solid DSSCs improved over 10% even near 20% from that of the liquid electrolyte before solidification. Besides, the employing of crosslinker I(CH2CH2O)nCH2CH2I showed higher electrolytic and cell characters than that of I(CH2)6I.

  18. The modelling of dynamic chemical state of paper machine unit operations; Dynaamisen kemiallisen tilan mallintaminen paperikoneen yksikkoeoperaatioissa - MPKT 04

    Energy Technology Data Exchange (ETDEWEB)

    Ylen, J.P.; Jutila, P. [Helsinki Univ. of Technology, Otaniemi (Finland)

    1998-12-31

    The chemical state of paper mass is considered to be a key factor to the smooth operation of the paper machine. There are simulators that have been developed either for dynamic energy and mass balances or for static chemical phenomena, but the combination of these is not a straight forward task. Control Engineering Laboratory of Helsinki University of Technology has studied the paper machine wet end phenomena with the emphasis on pH-modelling. VTT (Technical Research Centre of Finland) Process Physics has used thermodynamical modelling successfully in e.g. Bleaching processes. In this research the different approaches are combined in order to get reliable dynamical models and modelling procedures for various unit operations. A flexible pilot process will be constructed and different materials will be processed starting from simple inorganic substances (e.g. Calcium carbonate and distilled water) working towards more complex masses (thick pulp with process waters and various reagents). The pilot process is well instrumented with ion selective electrodes, total calcium analysator and all basic measurements. (orig.)

  19. Interactive state-space analysis of concurrent systems

    Energy Technology Data Exchange (ETDEWEB)

    Morgan, E.T.; Razouk, R.R.

    1987-10-01

    The introduction of concurrency into programs has added to the complexity of the software design process. This is most evident in the design of communications protocols where concurrency is inherent to the behavior of the system. The complexity exhibited by such software systems makes more evident the need for computer-aided tools for automatically analyzing behavior. The Distributed Systems project at UCI has been developing techniques and tools, based on Petri nets, which support the design and evaluation of concurrent software systems. Techniques based on constructing reachability graphs that represent projections and selections of complete state-spaces have been developed. This paper focuses attention on the computer-aided analysis of these graphs for the purpose of proving correctness of the modeled system. The application of the analysis technique to evaluating simulation results for correctness is discussed. The tool which supports this analysis (the reachability graph analyzer, RGA) is also described. This tool provides mechanisms for proving general system properties (e.g., deadlock-freeness) as well as system-specific properties. The tool is sufficiently general to allow a user to apply complex user-defined analysis algorithms to reachability graphs. The alternating-bit protocol, with a bounded channel, is used to demonstrate the power of the tool and to point to future extensions.

  20. Analysis of Chemical Constituents in Wuzi-Yanzong-Wan by UPLC-ESI-LTQ-Orbitrap-MS

    Directory of Open Access Journals (Sweden)

    Dixin Zou

    2015-12-01

    Full Text Available Wuzi-Yanzong-Wan (WZYZW, a classical traditional Chinese medicine (TCM prescription containing Fructus Lych, Semen Cuscutae (fried, Fructus Rubi, Fructus Schisandrae chinensis (steamed and Semen Plantaginis (fried with salt, is widely used to treat impotence, sterility, spermatorrhea, premature ejaculation, lumbago and post-micturation dribble. However, the chemical profile of WZYZW has not been established yet. In this work, a rapid and sensitive method for systematically screening and identifying the chemical constituents of WZYZW in both positive and negative ion modes using Ultra-Performance LC coupled with ESI-linear ion trap-Orbitrap tandem mass spectrometry (UPLC-ESI-LTQ-Orbitrap-MS has been developed. Based on the chromatographic and spectrometric data, and referring to the literature, we could tentatively identify 106 compounds, including organic acids, flavonoids, phenylpropanoids, alkaloids and terpenoids. Fourteen ingredients from Fructus Lych were identified, while 10 ingredients were from Semen Cuscutae (fried, 33 ingredients were from Fructus Rubi, 37 ingredients were from Fructus Schisandrae chinensis (steamed, and 20 ingredients were from Semen Plantaginis (fried with salt. The results may provide essential data for further quality control, pharmacological research and clinical evaluation of WZYZW. Furthermore, this study indicates the developed approach based on UPLC-ESI-LTQ-Orbitrap-MS is suitable for characterizing the chemical profiles of TCM prescriptions. This is the first report to provide a comprehensive analysis of the chemical constituents of WZYZW.

  1. Preparation and analysis of chemically gradient functional bioceramic coating formed by pulsed laser deposition.

    Science.gov (United States)

    Rajesh, P; Muraleedharan, C V; Sureshbabu, S; Komath, Manoj; Varma, Harikrishna

    2012-02-01

    Bioactive ceramic coatings based on calcium phosphates yield better functionality in the human body for a variety of metallic implant devices including orthopaedic and dental prostheses. In the present study chemically and hence functionally gradient bioceramic coating was obtained by pulsed laser deposition method. Calcium phosphate bioactive ceramic coatings based on hydroxyapatite (HA) and tricalcium phosphate (TCP) were deposited over titanium substrate to produce gradation in physico-chemical characteristics and in vitro dissolution behaviour. Sintered targets of HA and α-TCP were deposited in a multi target laser deposition system. The obtained deposits were characterized by X-ray diffraction, fourier transform infrared spectroscopy, scanning electron microscopy and energy dispersive X-ray analysis. Inductively coupled plasma spectroscopy was used to estimate the in vitro dissolution behaviour of coatings. The variation in mechanical property of the gradient layer was evaluated through scratch test and micro-indentation hardness. The bioactivity was examined in vitro with respect to the ability of HA layer to form on the surface as a result of contact with simulated body fluid. It could be inferred that chemically gradient functional bioceramic coating can be produced by laser deposition of multiple sintered targets with variable chemical composition.

  2. Steady–State Exergy Analysis of a Simple Solar Still

    Directory of Open Access Journals (Sweden)

    G. Cervantes–de Gortari.

    2010-01-01

    Full Text Available This paper presents a steady–state, theoretical exergy analysis of a solar still, focused on the exergy flows in the components of the still: collector plate, brine and glass cover. The analytical approach states an energy balance for each component resulting in three coupled equations where three parameters –solar irradiance, ambient temperature and insulation thickness– are studied. The energy balances are solved to find temperatures of each component; these temperatures are used to compute energy and exergy flows. Results in the steady–state regime show that the collector transports 13% of incident radiation exergy to the heat the brine, while in the brine the evaporation exergy accounts for the 6% of total exergy. Exergy/energy ratio shows that the most efficient component is the brine reaching more than 90% for almost any value of the parameters under study, while the collector has a 23% exergy/energy ratio for a 1,000 W/m2 solar energy input. The solar still is a device that uses efficiently the heating of a collector and the general discussion about its promotion should not, as it must be with almost every other solar device, be about thermodynamic limitations.

  3. Immigration and Muslim Immigrants: A Comparative Analysis of European States

    Directory of Open Access Journals (Sweden)

    Natasha T. Duncan

    2011-10-01

    Full Text Available Immigration policies serve a number of functions for states. Governments may use policies as instruments of foreign policy, economic growth, population growth, and/ or national security. In this post-September 11, 2001 global environment, integration policies have become more assimilationist and immigration restrictions toward nationals from Muslim countries of origin have increased in the name of national security. While this trend is common among many Western states, Britain’s immigration stance toward Muslim migrants remains unchanged. This study examines changes in policies toward immigrants—changes that make these policies de facto immigration policies though they may not have been conceived as such—in the Netherlands, Germany, France, and the absence of this change in the UK. It seeks to answer the question: what explains reforms in the Netherlands, Germany, and France while British immigration policy remained unchanged? In this effort, the article emphasizes the impact of these changes on potential migrants from predominantly Muslim countries of origin. Based on a comparative case study analysis using process tracing, findings indicate that Dutch immigration/integration policy choices influence government policy changes in other West European countries. Through a learning process, governments experiencing similar socio-political challenges observe overlapping societal responses to them and optimize in creating policy alternatives by using short-cuts and adopting policies implemented in comparable states and situations.

  4. Diagnostics of subtropical plants functional state by cluster analysis

    Directory of Open Access Journals (Sweden)

    Oksana Belous

    2016-05-01

    Full Text Available The article presents an application example of statistical methods for data analysis on diagnosis of the adaptive capacity of subtropical plants varieties. We depicted selection indicators and basic physiological parameters that were defined as diagnostic. We used evaluation on a set of parameters of water regime, there are: determination of water deficit of the leaves, determining the fractional composition of water and detection parameters of the concentration of cell sap (CCS (for tea culture flushes. These settings are characterized by high liability and high responsiveness to the effects of many abiotic factors that determined the particular care in the selection of plant material for analysis and consideration of the impact on sustainability. On the basis of the experimental data calculated the coefficients of pair correlation between climatic factors and used physiological indicators. The result was a selection of physiological and biochemical indicators proposed to assess the adaptability and included in the basis of methodical recommendations on diagnostics of the functional state of the studied cultures. Analysis of complex studies involving a large number of indicators is quite difficult, especially does not allow to quickly identify the similarity of new varieties for their adaptive responses to adverse factors, and, therefore, to set general requirements to conditions of cultivation. Use of cluster analysis suggests that in the analysis of only quantitative data; define a set of variables used to assess varieties (and the more sampling, the more accurate the clustering will happen, be sure to ascertain the measure of similarity (or difference between objects. It is shown that the identification of diagnostic features, which are subjected to statistical processing, impact the accuracy of the varieties classification. Selection in result of the mono-clusters analysis (variety tea Kolhida; hazelnut Lombardsky red; variety kiwi Monty

  5. Surface desorption atmospheric pressure chemical ionization mass spectrometry for direct ambient sample analysis without toxic chemical contamination.

    Science.gov (United States)

    Chen, Huanwen; Zheng, Jian; Zhang, Xie; Luo, Mingbiao; Wang, Zhichang; Qiao, Xiaolin

    2007-08-01

    Ambient mass spectrometry, pioneered with desorption electrospray ionization (DESI) technique, is of increasing interest in recent years. In this study, a corona discharge ionization source is adapted for direct surface desorption chemical ionization of compounds on various surfaces at atmospheric pressure. Ambient air, with about 60% relative humidity, is used as a reagent to generate primary ions such as H(3)O(+), which is then directed to impact the sample surface for desorption and ionization. Under experimental conditions, protonated or deprotonated molecules of analytes present on various samples are observed using positive or negative corona discharge. Fast detection of trace amounts of analytes present in pharmaceutical preparations, viz foods, skins and clothes has been demonstrated without any sample pretreatment. Taking the advantage of the gasless setup, powder samples such as amino acids and mixtures of pharmaceutical preparations are rapidly analyzed. Impurities such as sudan dyes in tomato sauce are detected semiquantitatively. Molecular markers (e.g. putrescine) for meat spoilage are successfully identified from an artificially spoiled fish sample. Chemical warfare agent stimulants, explosives and herbicides are directly detected from the skin samples and clothing exposed to these compounds. This provides a detection limit of sub-pg (S/N > or = 3) range in MS2. Metabolites and consumed chemicals such as glucose are detected successfully from human skins. Conclusively, surface desorption atmospheric pressure chemical ionization (DAPCI) mass spectrometry, without toxic chemical contamination, detects various compounds in complex matrices, showing promising applications for analyses of human related samples.

  6. State analysis requirements database for engineering complex embedded systems

    Science.gov (United States)

    Bennett, Matthew B.; Rasmussen, Robert D.; Ingham, Michel D.

    2004-01-01

    It has become clear that spacecraft system complexity is reaching a threshold where customary methods of control are no longer affordable or sufficiently reliable. At the heart of this problem are the conventional approaches to systems and software engineering based on subsystem-level functional decomposition, which fail to scale in the tangled web of interactions typically encountered in complex spacecraft designs. Furthermore, there is a fundamental gap between the requirements on software specified by systems engineers and the implementation of these requirements by software engineers. Software engineers must perform the translation of requirements into software code, hoping to accurately capture the systems engineer's understanding of the system behavior, which is not always explicitly specified. This gap opens up the possibility for misinterpretation of the systems engineer's intent, potentially leading to software errors. This problem is addressed by a systems engineering tool called the State Analysis Database, which provides a tool for capturing system and software requirements in the form of explicit models. This paper describes how requirements for complex aerospace systems can be developed using the State Analysis Database.

  7. Embedded Fragments from U.S. Military Personnel—Chemical Analysis and Potential Health Implications

    Directory of Open Access Journals (Sweden)

    José A. Centeno

    2014-01-01

    Full Text Available Background: The majority of modern war wounds are characterized by high-energy blast injuries containing a wide range of retained foreign materials of a metallic or composite nature. Health effects of retained fragments range from local or systemic toxicities to foreign body reactions or malignancies, and dependent on the chemical composition and corrosiveness of the fragments in vivo. Information obtained by chemical analysis of excised fragments can be used to guide clinical decisions regarding the need for fragment removal, to develop therapeutic interventions, and to better anticipate future medical problems from retained fragment related injuries. In response to this need, a new U.S Department of Defense (DoD directive has been issued requiring characterization of all removed fragments to provide a database of fragment types occurring in combat injuries. Objectives: The objective of this study is to determine the chemical composition of retained embedded fragments removed from injured military personnel, and to relate results to histological findings in tissue adjacent to fragment material. Methods: We describe an approach for the chemical analysis and characterization of retained fragments and adjacent tissues, and include case examples describing fragments containing depleted uranium (DU, tungsten (W, lead (Pb, and non-metal foreign bodies composed of natural and composite materials. Fragments obtained from four patients with penetrating blast wounds to the limbs were studied employing a wide range of chemical and microscopy techniques. Available adjacent tissues from three of the cases were histologically, microscopically, and chemically examined. The physical and compositional properties of the removed foreign material surfaces were examined with energy dispersive x-ray fluorescence spectrometry (EDXRF, scanning electron microscopy (SEM, laser ablation inductively-coupled plasma mass-spectrometry (LA-ICP-MS, and confocal laser Raman

  8. Chemical analysis of turmeric from Minas Gerais, Brazil and comparison of methods for flavour free oleoresin

    Directory of Open Access Journals (Sweden)

    Cyleni R. A. Souza

    1998-01-01

    Full Text Available Chemical analysis of turmeric (Curcuma longa L cultivated in eight different cities in the state of Minas Gerais, Brazil was carried out. The levels of curcuminoid pigments varied from 1.4 to 6.14 g/100 g and of volatile oil from 0.97 to 7.55 mL/100 g (dry basis. Samples from Patrocínio, Arinos and Brasilândia contained higher pigment levels compared to the others. The sample from Patrocínio contained the highest volatile oil content. The mean levels of ethyl ether extract, protein, fiber, ash and starch were 8.51, 7.01, 7.22, 7.81 and 39.87 g/100 g dry basis, respectively. Laboratory extraction of flavour free oleoresin was performed in triplicate. A higher yield of pigment in the oleoresin was obtained when the volatile oil was extracted with water vapor and the oleoresin with ethanol. The oleoresin obtained was free of flavour and could be used in a wider range of food applications.Análise química de cúrcuma (Curcuma longa L provenientes de oito municípios do Estado de Minas Gerais - Brasil foi efetuada. Os teores (base seca de pigmentos curcuminóides variaram de 1,4 a 6,14 g/100 g e os de óleo volátil, de 0,97 a 7,55 mL/100 g. Amostras de Patrocínio, Arinos e Brasilândia continham os maiores teores de pigmentos e as de Patrocínio os maiores teores de óleos voláteis. Os teores médios (base seca de extrato etéreo, proteínas, fibras, cinzas e amido encontrados foram 8,51; 7,01; 7,22; 7,81 e 39,87 g/100 g, respectivamente. Com o objetivo de obter corante amarelo isento de flavor, métodos de extração em laboratório foram comparados em triplicata. Um maior rendimento de pigmento na oleoresina foi obtido extraindo-se o óleo volátil com vapor d'água e a oleoresina com etanol. A oleoresina obtida é isenta de flavor e pode ser utilizada em um número maior de aplicações na indústria alimentícia

  9. In situ Analysis of Organic Compounds on Mars using Chemical Derivatization and Gas Chromatography Mass Spectrometry

    Science.gov (United States)

    Glavin, D. P.; Buch, A.; Cabane, M.; Coll, P.; Navarro-Gonzalez, R.; Mahaffy, P. R.

    2005-01-01

    One of the core science objectives of NASA's 2009 Mars Science Laboratory (MSL) mission is to determine the past or present habitability of Mars. The search for key organic compounds relevant to terrestrial life will be an important part of that assessment. We have developed a protocol for the analysis of amino acids and carboxylic acids in Mars analogue materials using gas chromatography mass spectrometry (GCMS). As shown, a variety of carboxylic acids were readily identified in soil collected from the Atacama Desert in Chile at part-per-billion levels by GCMS after extraction and chemical derivatization using the reagent N,N-tert.-butyl (dimethylsilyl) trifluoroacetamide (MTBSTFA). Several derivatized amino acids including glycine and alanine were also detected by GCMS in the Atacama soil at lower concentrations (chromatogram not shown). Lacking derivatization capability, the Viking pyrolysis GCMS instruments could not have detected amino acids and carboxylic acids, since these non-volatile compounds require chemical transformation into volatile species that are stable in a GC column. We are currently optimizing the chemical extraction and derivatization technique for in situ GCMS analysis on Mars. Laboratory results of analyses of Atacama Desert samples and other Mars analogue materials using this protocol will be presented.

  10. Humidity independent mass spectrometry for gas phase chemical analysis via ambient proton transfer reaction.

    Science.gov (United States)

    Zhu, Hongying; Huang, Guangming

    2015-03-31

    In this work, a humidity independent mass spectrometric method was developed for rapid analysis of gas phase chemicals. This method is based upon ambient proton transfer reaction between gas phase chemicals and charged water droplets, in a reaction chamber with nearly saturate humidity under atmospheric pressure. The humidity independent nature enables direct and rapid analysis of raw gas phase samples, avoiding time- and sample-consuming sample pretreatments in conventional mass spectrometry methods to control sample humidity. Acetone, benzene, toluene, ethylbenzene and meta-xylene were used to evaluate the analytical performance of present method. The limits of detection for benzene, toluene, ethylbenzene and meta-xylene are in the range of ∼0.1 to ∼0.3 ppbV; that of benzene is well below the present European Union permissible exposure limit for benzene vapor (5 μg m(-3), ∼1.44 ppbV), with linear ranges of approximately two orders of magnitude. The majority of the homemade device contains a stainless steel tube as reaction chamber and an ultrasonic humidifier as the source of charged water droplets, which makes this cheap device easy to assemble and facile to operate. In addition, potential application of this method was illustrated by the real time identification of raw gas phase chemicals released from plants at different physiological stages.

  11. NON-EQUILIBRIUM STATIONARY STATE IN CHEMICAL REACTION OF SiO2/Fe AT INTERFACE OF SLAG/METAL AND ITS STABILITY DURING ARC WELDING

    Institute of Scientific and Technical Information of China (English)

    LI Xiaoquan; DU Zeyu; YANG Xuguang

    2007-01-01

    For characteristics of open and far from thermodynamic equilibrium in welding chemical reaction, a new kind of quantitative method, which is used to analyze direction and extent for chemical reaction of SiO2/Fe during quasi-steady state period, is introduced with the concept of non-equilibrium stationary state. The main idea is based on thermodynamic driving forces, which result in non-zero thermodynamic fluxes and lead to chemical reaction far away from thermodynamic equilibrium. There exists certain dynamic equilibrium relationship between rates of diffusion fluxes in liquid phase of reactants or products and the rate equation of chemical reaction when welding is in quasi-steady state. As result of this, a group of non-linear equations containing concentrations of all substances at interface of slag/liquid-metal may be established. Moreover the stability of this non-equilibrium stationary state is discussed using dissipative structure theory and it is concluded theoretically that this non-equilibrium stationary state for welding chemical reaction is of stability.

  12. Weak error analysis of approximate simulation methods for multi-scale stochastic chemical kinetic systems

    CERN Document Server

    Anderson, David F

    2011-01-01

    A chemical reaction network is a chemical system involving multiple reactions and chemical species. The simplest stochastic models of such networks treat the system as a continuous time Markov chain with the state being the number of molecules of each species and with reactions modeled as possible transitions of the chain. In this paper we provide a general framework for understanding the weak error of numerical approximation techniques in this setting. For such models, there is typically a wide variation in scales in that the different species and reaction rates vary over several orders of magnitude. Quantifying how different numerical approximation techniques behave in this setting therefore requires that these scalings be taken into account in an appropriate manner. We quantify how the error of different methods depends upon both the natural scalings within a given system, and with the step-size of the numerical method. We show that Euler's method, also called explicit tau-leaping, acts as an order one met...

  13. Today's and tomorrow's bio-based bulk chemicals from white biotechnology: a techno-economic analysis.

    Science.gov (United States)

    Hermann, B G; Patel, M

    2007-03-01

    Little information is yet available on the economic viability of the production of bio-based bulk chemicals and intermediates from white biotechnology (WB). This paper details a methodology to systematically evaluate the techno-economic prospects of present and future production routes of bio-based bulk chemicals produced with WB. Current and future technology routes are evaluated for 15 products assuming prices of fermentable sugar between 70 euro/t and 400 euro/t and crude oil prices of US $25/barrel and US $50/barrel. The results are compared to current technology routes of petrochemical equivalents. For current state-of-the-art WB processes and a crude oil price of US $25/barrel, WB-based ethanol, 1,3-propanediol, polytrimethylene terephthalate and succinic acid are economically viable. Only three WB products are economically not viable for future technology: acetic acid, ethylene and PLA. Future-technology ethylene and PLA become economically viable for a higher crude oil price (US $50/barrel). Production costs plus profits of WB products decrease by 20-50% when changing from current to future technology for a crude oil price of US $25 per barrel and across all sugar prices. Technological progress in WB can thus contribute significantly to improved economic viability of WB products. A large-scale introduction of WB-based production of economically viable bulk chemicals would therefore be desirable if the environmental impacts are smaller than those of current petrochemical production routes.

  14. Computer-Aided Modelling of Short-Path Evaporation for Chemical Product Purification, Analysis and Design

    DEFF Research Database (Denmark)

    Sales-Cruz, Alfonso Mauricio; Gani, Rafiqul

    2006-01-01

    An important stage in the design process for many chemical products is its manufacture where, for a class of chemical products that may be thermally unstable (such as, drugs, insecticides, flavours /fragrances, and so on), the purification step plays a major role. Short-path evaporation is a safe...... method, suitable for separation and purification of thermally unstable materials whose design and analysis can be efficiently performed through reliable model-based techniques. This paper presents a generalized model for short-path evaporation and highlights its development, implementation and solution...... glycerol, mono-, di- and triglycerides, and (b) the recovery of a pharmaceutical product from a six-component mixture. Validation of the short-path evaporation model is highlighted through the comparison of experimental data from an industrial pilot plant with the simulated results from the model. Also...

  15. Thermo-chemical, mechanical and resin flow integrated analysis in pultrusion

    Science.gov (United States)

    Carlone, Pierpaolo; Rubino, Felice; Palazzo, Gaetano S.

    2016-10-01

    The present work discusses some numerical outcomes provided by an integrated analysis of impregnation, thermo-chemical and stress/strain aspects in a conventional pultrusion process. The impregnation models describes resin flow and pressure distribution in the initial portion of the die, solving a non-homogeneous non-isothermal/reactive multiphase problem, using a finite volume scheme. The thermochemical model describes the heat transfer and degree of cure evolution of the processing resin. Finally, the stress/strain model computes the part distortion and in process stresses due to thermal, chemical, mechanical strains. An applicative case study is presented, simulating the impregnation step of the pultrusion process of a fiberglass-epoxy resin composite rod.

  16. Variability of biomass chemical composition and rapid analysis using FT-NIR techniques

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Lu [University of Tennessee, Knoxville (UTK); Ye, Philip [University of Tennessee, Knoxville (UTK); Womac, A.R. [University of Tennessee; Sokhansanj, Shahabaddine [ORNL

    2010-04-01

    A quick method for analyzing the chemical composition of renewable energy biomass feedstock was developed by using Fourier transform near-infrared (FT-NIR) spectroscopy coupled with multivariate analysis. The study presents the broad-based model hypothesis that a single FT-NIR predictive model can be developed to analyze multiple types of biomass feedstock. The two most important biomass feedstocks corn stover and switchgrass were evaluated for the variability in their concentrations of the following components: glucan, xylan, galactan, arabinan, mannan, lignin, and ash. A hypothesis test was developed based upon these two species. Both cross-validation and independent validation results showed that the broad-based model developed is promising for future chemical prediction of both biomass species; in addition, the results also showed the method's prediction potential for wheat straw.

  17. Chemical contents in Lygeum spartum L. using instrumental neutron activation analysis

    Energy Technology Data Exchange (ETDEWEB)

    Nedjimi, Bouzid [Djelfa Univ. (Algeria). Lab. of Exploration and Valorization of Steppe Ecosystem; Beladel, Brahim [Djelfa Univ. (Algeria)

    2015-09-01

    The present investigation was conducted to determine the chemical contents of Lygeum spartum L. (Poaceae). Samples were analyzed in order to determine essential (Ca, K, Na, Fe, Co) and some potentially toxic elements (Eu, Sb, Tb) using instrumental neutron activation analysis (INAA). In general chemical element contents were in substantial amounts to meet adult sheep requirements. Potential intake of Ca, K, Zn, Co and Fe by ruminant weighing 50 kg BW consuming 2.0 kg per day DM was sufficient to satisfy their requirements. However, only Na level was still insufficient to meet the requirements for grazing ruminants. Potential toxic elements in this species were within the safety baseline of all the assayed elements recommended by NRC. Na supplementation would seem to be necessary in this zone, for optimum productivity of grazing animals.

  18. PACSY, a relational database management system for protein structure and chemical shift analysis.

    Science.gov (United States)

    Lee, Woonghee; Yu, Wookyung; Kim, Suhkmann; Chang, Iksoo; Lee, Weontae; Markley, John L

    2012-10-01

    PACSY (Protein structure And Chemical Shift NMR spectroscopY) is a relational database management system that integrates information from the Protein Data Bank, the Biological Magnetic Resonance Data Bank, and the Structural Classification of Proteins database. PACSY provides three-dimensional coordinates and chemical shifts of atoms along with derived information such as torsion angles, solvent accessible surface areas, and hydrophobicity scales. PACSY consists of six relational table types linked to one another for coherence by key identification numbers. Database queries are enabled by advanced search functions supported by an RDBMS server such as MySQL or PostgreSQL. PACSY enables users to search for combinations of information from different database sources in support of their research. Two software packages, PACSY Maker for database creation and PACSY Analyzer for database analysis, are available from http://pacsy.nmrfam.wisc.edu.

  19. Estimation and Prediction of Bioconcentration Factors of Nonionic Organic Chemicals in Fish by Electrotopological State Indices and Structural Parameter

    Institute of Scientific and Technical Information of China (English)

    FENG Chang-Jun; YANG Wei-Hua; MU Lai-Long

    2008-01-01

    Based on the characteristics of atom types, Hall's electrotopological state indices (En) are calculated for 165 nonionic organic compounds. On the basis of the characteristics of substituent and conjugated matrix, a novel molecular structure parameter (G) is defined and calcu- lated for 165 molecules in this paper. En and G show good structural selectivity for organic molecules. G, a satisfactory relationship between bioconcentration factor (BCF) and En, is expressed as: lgBCF = -0.283 + 1.246G + 0.079E42 + 0.351E9 - 0.063E17 (n' = 122, R = 0.967, F = 425.636, s = 0.394), which could provide estimation and prediction for the lgBCF of nonionic organic chemicals. Furthermore, the model is examined to validate overall robustness with Jackknife tests, and the independent variables in model do not exist cross correlation with VIF. All these regression results show that the new parameter G and electrotopological state index have good rationality and efficiency. It is concluded that the En and G will be used widely in quantitative structure-property/activity relationship (QSPR/QSAR) research.

  20. Probing physical and chemical changes in cortical bone due to osteoporosis and type 2 diabetes by solid-state NMR

    Science.gov (United States)

    Zhou, Donghua; Taylor, Amanda; Rendina, Beth; Smith, Brenda; Department of Physics Collaboration; Department of Nutritional Sciences Collaboration

    2013-03-01

    Approximately 1.5 million fractures occur each year in the U.S. due to osteoporosis, which is characterized by decreased bone mineral density and deterioration of bone micro-architecture. On the other hand, type 2 diabetes also significantly increases fracture risks, despite having a normal or even higher bone mineral density. Solid-state NMR has been applied to bone tissues from normal and disease-inflicted mouse models to study structural and chemical dynamics as the disease progresses. Proton relaxation experiments were performed to measure water populations in the bone matrix and pores. Collagen-bound water has strong influence on bone resilience, while water content in the pores reveals amount and size of pores from micro- to millimeter range. Other biochemical and atomic-scale structural alterations in the mineral and organic phases and their interface were investigated by proton, phosphorus, and carbon NMR spectroscopy. Experiments were designed to individually detect different types of phosphorus environments: near the mineral surface, similar to hydroxyapatite, and deficient of hydrogens due to substitution of the hydroxyl group by other ions. A new method was also developed for accurate quantification of each phosphorus species. The authors appreciate financial support for this project from the College of Human Sciences and the College of Arts and Sciences, Oklahoma State University.