Science.gov

Sample records for chemical flowsheet conditions

  1. Use of Flowsheet Monitoring to Perform Environmental Evaluation of Chemical Process Flowsheets

    EPA Science Inventory

    Flowsheet monitoring interfaces have been proposed to the Cape-Open Laboratories Network to enable development of applications that access to multiple parts of the flowsheet or its thermodynamic models, without interfering with the flowsheet itself. These flowsheet monitoring app...

  2. Dynamic displays of chemical process flowsheet models

    SciTech Connect

    Aull, J.E.

    1996-11-01

    This paper describes the algorithms used in constructing dynamic graphical displays of a process flowsheet. Movies are created which portray changes in the process over time using animation in the flowsheet such as individual streams that take on a color keyed to the current flow rate, tank levels that visibly rise and fall and {open_quotes}gauges{close_quotes} that move to display parameter values. Movies of this type can be a valuable tool for visualizing, analyzing, and communicating the behavior of a process model. This paper describes the algorithms used in constructing displays of this kind for dynamic models using the SPEEDUP{trademark} modeling package and the GMS{trademark} graphics package. It also tells how data is exported from the SPEEDUP{trademark} package to GMS{trademark} and describes how a user environment for running movies and editing flowsheets is set up. The algorithms are general enough to be applied to other processes and graphics packages. In fact the techniques described here can be used to create movies of any time-dependent data.

  3. FY13 GLYCOLIC-NITRIC ACID FLOWSHEET DEMONSTRATIONS OF THE DWPF CHEMICAL PROCESS CELL WITH SIMULANTS

    SciTech Connect

    Lambert, D.; Zamecnik, J.; Best, D.

    2014-03-13

    Savannah River Remediation is evaluating changes to its current Defense Waste Processing Facility flowsheet to replace formic acid with glycolic acid in order to improve processing cycle times and decrease by approximately 100x the production of hydrogen, a potentially flammable gas. Higher throughput is needed in the Chemical Processing Cell since the installation of the bubblers into the melter has increased melt rate. Due to the significant maintenance required for the safety significant gas chromatographs and the potential for production of flammable quantities of hydrogen, eliminating the use of formic acid is highly desirable. Previous testing at the Savannah River National Laboratory has shown that replacing formic acid with glycolic acid allows the reduction and removal of mercury without significant catalytic hydrogen generation. Five back-to-back Sludge Receipt and Adjustment Tank (SRAT) cycles and four back-to-back Slurry Mix Evaporator (SME) cycles were successful in demonstrating the viability of the nitric/glycolic acid flowsheet. The testing was completed in FY13 to determine the impact of process heels (approximately 25% of the material is left behind after transfers). In addition, back-to-back experiments might identify longer-term processing problems. The testing was designed to be prototypic by including sludge simulant, Actinide Removal Product simulant, nitric acid, glycolic acid, and Strip Effluent simulant containing Next Generation Solvent in the SRAT processing and SRAT product simulant, decontamination frit slurry, and process frit slurry in the SME processing. A heel was produced in the first cycle and each subsequent cycle utilized the remaining heel from the previous cycle. Lower SRAT purges were utilized due to the low hydrogen generation. Design basis addition rates and boilup rates were used so the processing time was shorter than current processing rates.

  4. Collaborative flowsheet development studies using cobalt dicarbollide and phosphine oxide for the partitioning of radionuclides from Idaho Chemical Processing Plant high-activity liquid waste with centrifugal contactors

    SciTech Connect

    Law, J.D.; Herbst, R.S.; Todd, T.A.

    1996-12-31

    Two solvent extraction technologies under development in Russia for the partitioning of radionuclides from radioactive wastes were tested at the Idaho Chemical Processing Plant (ICPP) with simulated high-activity liquid waste (HAW) on a continuous basis using 24 stages of 2-cm diameter centrifugal contactors. Two flowsheet tests were conducted with chlorinated cobalt dicarbollide (ChCoDiC) to evaluate the separation of cesium and strontium from ICPP HAW. Also, a flowsheet test was performed with a derivative of phosphine oxide (POR) to evaluate the separation of actinides, rare earths, and technetium from ICPP HAW. All experiments utilized a non-radioactive HAW simulant prepared to emulate the macro (or matrix) constituents of actual ICPP HAW at their average tank composition. The behavior of the species of interest was monitored using the stable forms of Sr and Cs, europium as a surrogate for americium, and rhenium as a surrogate for technetium. Removal efficiencies and distribution coefficients were determined for each flowsheet at steady-state conditions. Results of this testing indicate the POR and ChCoDiC processes can be used to effectively treat ICPP HAW. This series of tests is a continuation of ongoing efforts to evaluate the applicability of these Russian developed technologies to U.S. nuclear wastes under the auspices of a joint program between the U.S. Department of Energy and the Russian Ministry of Atomic Energy.

  5. GLYCOLIC-NITRIC ACID FLOWSHEET DEMONSTRATION OF THE DWPF CHEMICAL PROCESS CELL WITH SLUDGE AND SUPERNATE SIMULANTS

    SciTech Connect

    Lambert, D.; Stone, M.; Newell, J.; Best, D.; Zamecnik, J.

    2012-08-28

    Savannah River Remediation (SRR) is evaluating changes to its current Defense Waste Processing Facility (DWPF) flowsheet to improve processing cycle times. This will enable the facility to support higher canister production while maximizing waste loading. Higher throughput is needed in the Chemical Process Cell (CPC) since the installation of the bubblers into the melter has increased melt rate. Due to the significant maintenance required for the DWPF gas chromatographs (GC) and the potential for production of flammable quantities of hydrogen, reducing or eliminating the amount of formic acid used in the CPC is being developed. Earlier work at Savannah River National Laboratory has shown that replacing formic acid with an 80:20 molar blend of glycolic and formic acids has the potential to remove mercury in the SRAT without any significant catalytic hydrogen generation. This report summarizes the research completed to determine the feasibility of processing without formic acid. In earlier development of the glycolic-formic acid flowsheet, one run (GF8) was completed without formic acid. It is of particular interest that mercury was successfully removed in GF8, no formic acid at 125% stoichiometry. Glycolic acid did not show the ability to reduce mercury to elemental mercury in initial screening studies, which is why previous testing focused on using the formic/glycolic blend. The objective of the testing detailed in this document is to determine the viability of the nitric-glycolic acid flowsheet in processing sludge over a wide compositional range as requested by DWPF. This work was performed under the guidance of Task Technical and Quality Assurance Plan (TT&QAP). The details regarding the simulant preparation and analysis have been documented previously.

  6. Nitric acid flowsheet with late wash PHA testing. Task Technical Plan, Integrated DWPF Melter System

    SciTech Connect

    Zamecnik, J.R.

    1993-10-28

    This Task Technical Plan outlines the activities to be conducted in the Integrated DWPF Melter System (IDMS) in ongoing support of the Defense Waste Processing Facility (DWPF) Chemical Process Cell (CPC) utilizing the Nitric Acid Flowsheet in the Sludge Receipt and Adjustment Tank (SRAT) and Precipitate Hydrolysis Aqueous (PHA) produced by the Late Wash Flowsheet. The IDMS facility is to be operated over a series of runs (2 to 4) using the Nitric Acid Flowsheet. The PHA will be produced with the Late Wash Flowsheet in the Precipitate Hydrolysis Experimental Facility (PHEF). All operating conditions shall simulate the expected DWPF operating conditions as closely as possible. The task objectives are to perform at least two IDMS runs with as many operating conditions as possible at nominal DWPF conditions. The major purposes of these runs are twofold: verify that the combined Late Wash and Nitric Acid flowsheets produce glass of acceptable quality without additional changes to process equipment, and determine the reproducibility of data from run to run. These runs at nominal conditions will be compared to previous runs made with PHA produced from the Late Wash flowsheet and with the Nitric Acid flowsheet in the SRAT (Purex 4 and Purex 5).

  7. GLYCOLIC-NITRIC ACID FLOWSHEET DEMONSTRATION OF THE DWPF CHEMICAL PROCESSING CELL WITH MATRIX SIMULANTS AND SUPERNATE

    SciTech Connect

    Lambert, D.; Stone, M.; Newell, J.; Best, D.

    2012-05-07

    Savannah River Remediation (SRR) is evaluating changes to its current DWPF flowsheet to improve processing cycle times. This will enable the facility to support higher canister production while maximizing waste loading. Higher throughput is needed in the CPC since the installation of the bubblers into the melter has increased melt rate. Due to the significant maintenance required for the DWPF gas chromatographs (GC) and the potential for production of flammable quantities of hydrogen, reducing or eliminating the amount of formic acid used in the CPC is being developed. Earlier work at Savannah River National Laboratory has shown that replacing formic acid with an 80:20 molar blend of glycolic and formic acids has the potential to remove mercury in the SRAT without any significant catalytic hydrogen generation. This report summarizes the research completed to determine the feasibility of processing without formic acid. In earlier development of the glycolic-formic acid flowsheet, one run (GF8) was completed without formic acid. It is of particular interest that mercury was successfully removed in GF8, no formic acid at 125% stoichiometry. Glycolic acid did not show the ability to reduce mercury to elemental mercury in initial screening studies, which is why previous testing focused on using the formic/glycolic blend. The objective of the testing detailed in this document is to determine the viability of the nitric-glycolic acid flowsheet in processing sludge over a wide compositional range as requested by DWPF. This work was performed under the guidance of Task Technical and Quality Assurance Plan (TT and QAP). The details regarding the simulant preparation and analysis have been documented previously.

  8. Chemical conditioning of sludge.

    PubMed

    Novak, J T; Park, C

    2004-01-01

    With all the advances made in understanding the structure and composition of sewage sludges, chemical conditioning remains a trial and error process, both with regard to the type and dose of conditioner needed. Recent studies at Virginia Tech have found that biological floc consists of two types of biopolymer, material associated with iron and aluminium and material associated with calcium and magnesium. These materials behave differently when sludges undergo digestion. This results in very different material being released into solution during digestion and very different conditioning requirements. This study shows that the primary materials released during anaerobic digestion are proteins and coagulation of the colloidal protein fraction in solution is the primary mechanism for conditioning. For aerobically digested sludges, both proteins and polysaccharides make up the colloid fraction, which interferes with dewatering. This research also shows that the effectiveness of the digestion process as characterized by volatile solids destruction is directly related to the chemical dose required for conditioning. That is, as the solids destruction increases, the conditioning chemical requirement also increases. Well digested sludges dewater more poorly and require more conditioning chemical than those with less volatile solids destruction. PMID:15259940

  9. Classic Nuclear Fuel Reprocessing Flowsheet

    SciTech Connect

    Fallgren, Andrew James

    2015-02-13

    This is a flowsheet as well as a series of subsheets to be used for discussion on the standard design of a reprocessing plant. This flowsheet consists of four main sections: offgas handling, separations, solvent wash, and acid recycle. As well as having the main flowsheet, subsections have been broken off into their own sheets to provide for larger font and ease of printing.

  10. GLYCOLIC - FORMIC ACID FLOWSHEET DEVELOPMENT

    SciTech Connect

    Pickenheim, B.; Stone, M.; Newell, J.

    2010-11-08

    Flowsheet testing was performed to further develop the nitric/glycolic/formic acid flowsheet as an alternative to the nitric/formic flowsheet currently being processed at the DWPF. This new flowsheet has shown that mercury can be removed in the Sludge Receipt and Adjustment Tank (SRAT) with minimal hydrogen generation. All other processing objectives were also met, including greatly reducing the Slurry Mix Evaporator (SME) product yield stress as compared to the baseline nitric/formic flowsheet. Eight runs were performed in total, including the baseline run. The baseline nitric/formic flowsheet run was extremely difficult to process under existing DWPF acceptance criteria with this simulant at the HM levels of noble metals. While nitrite was destroyed and mercury was removed to near the DWPF limit, the rheology of the SRAT and SME products were well above design basis and hydrogen generation far exceeded the DWPF limit. In addition, mixing during the SME cycle was very poor. In this sense, the nitric/glycolic/formic acid flowsheet represents a significant upgrade over the current flowsheet. In the nitric/glycolic/formic flowsheet runs, mercury was successfully removed with almost no hydrogen generation and the SRAT and SME products yield stresses were within process limits or previously processed ranges. It is recommended that DWPF continue to support development of the nitric/glycolic/formic flowsheet. Although experience is limited at this time, this flowsheet meets or outperforms the current flowsheet in many regards, including off-gas generation, mercury removal, product rheology and general ease of processing. Additional flowsheet testing will allow for a more thorough understanding of the chemistry and effectiveness of the flowsheet over a range of sludge compositions and formic/glycolic ratios. This testing will also show whether the REDOX and metal solubility concerns with this change in the flowsheet can be addressed by just adjusting the volumes of

  11. Technetium removal: preliminary flowsheet options

    SciTech Connect

    Eager, K.M.

    1995-10-24

    This document presents the results of a preliminary investigation into options for preliminary flowsheets for 99Tc removal from Hanford Site tank waste. A model is created to show the path of 99Tc through pretreatment to disposal. The Tank Waste Remediation (TWRS) flowsheet (Orme 1995) is used as a baseline. Ranges of important inputs to the model are developed, such as 99Tc inventory in the tanks and important splits through the TWRS flowsheet. Several technetium removal options are discussed along with sensitivities of the removal schemes to important model parameters

  12. Ruthenium volatility from the vitrification of melter feeds prepared using the Nitric Acid Flowsheet

    SciTech Connect

    Hutson, N.D.

    1992-10-22

    The present DWPF flowsheet calls for the chemical treatment of waste sludge with 90 wt% formic acid prior to the addition of the Precipitate Hydrolysis Aqueous (PHA) product. An alternative processing methodology, denoted the ``Nitric Acid Flowsheet``, has been proposed. In the application of this flowsheet, nitric acid would be used to neutralize sludge base components (hydroxides and carbonates) prior to the addition of late wash PHA. The late wash PHA will contain sufficient quantities of formic acid to adequately complete necessary reduction-oxidation (REDOX) reactions.

  13. An evaluation of mercury removal in the IDMS using the nitric acid flowsheet

    SciTech Connect

    Hutson, N.D.

    1992-10-22

    The present DWPF flowsheet calls for the chemical treatment of waste sludge with 90 wt % formic acid prior to the addition of the Precipitate Hydrolysis Aqueous (PHA) product. An alternative processing methodology, denoted the ``Nitric Acid Flowsheet``, has been proposed. in the application of this flowsheet, nitric acid would be used to neutralize sludge base components (hydroxides and carbonates) prior to the addition of late wash PHA. The late wash PHA will contain sufficient quantities of formic acid to adequately complete necessary reduction-oxidation (REDOX) reactions.

  14. Ruthenium volatility from the vitrification of melter feeds prepared using the Nitric Acid Flowsheet

    SciTech Connect

    Hutson, N.D.

    1992-10-22

    The present DWPF flowsheet calls for the chemical treatment of waste sludge with 90 wt% formic acid prior to the addition of the Precipitate Hydrolysis Aqueous (PHA) product. An alternative processing methodology, denoted the Nitric Acid Flowsheet'', has been proposed. In the application of this flowsheet, nitric acid would be used to neutralize sludge base components (hydroxides and carbonates) prior to the addition of late wash PHA. The late wash PHA will contain sufficient quantities of formic acid to adequately complete necessary reduction-oxidation (REDOX) reactions.

  15. An evaluation of mercury removal in the IDMS using the nitric acid flowsheet

    SciTech Connect

    Hutson, N.D.

    1992-10-22

    The present DWPF flowsheet calls for the chemical treatment of waste sludge with 90 wt % formic acid prior to the addition of the Precipitate Hydrolysis Aqueous (PHA) product. An alternative processing methodology, denoted the Nitric Acid Flowsheet'', has been proposed. in the application of this flowsheet, nitric acid would be used to neutralize sludge base components (hydroxides and carbonates) prior to the addition of late wash PHA. The late wash PHA will contain sufficient quantities of formic acid to adequately complete necessary reduction-oxidation (REDOX) reactions.

  16. Uranium-Molybdenum Dissolution Flowsheet Studies

    SciTech Connect

    Pierce, R. A.

    2007-03-01

    concentrate within the charge bundles. Solubility behavior of the SK material during dissolution at 70 o C reflected data reported in the literature for 100 o C. When solutions containing solids at 70 o C were heated to 105 o C, the solids dissolved. After 21 days, the samples that had been heated closely resembled the non-heated ones with respect to solids content. Super-saturated solutions of U-Mo have been produced which can be stable for more than 10 days, but these conditions are outside of the bounds of the recommended flowsheet. It is not known how the different dissolution pathways affect solution stability, but the results agree with the fact that solubility should not be affected by the dissolution pathway. Therefore, the literature data should be used as the bounding condition for solubility. Dissolution of the SK material consumed 2.8-8.0 moles of acid per mole of metal dissolved, which agrees with behavior reported elsewhere for U and U-Mo metals. The acid consumption values confirmed that a starting acid concentration in the dissolver of 4.0-5.0 M HNO3 will allow H-Canyon Operations to avoid adjusting the feed from the dissolver prior to solvent extraction while providing maximum operating margin for avoiding precipitate formation.

  17. DEMONSTRATION OF THE GLYCOLIC-FORMIC FLOWSHEET IN THE SRNL SHIELDED CELLS USING ACTUAL WASTE

    SciTech Connect

    Lambert, D.; Pareizs, J.; Click, D.

    2011-11-07

    Glycolic acid was effective at dissolving many metals, including iron, during processing with simulants. Criticality constraints take credit for the insolubility of iron during processing to prevent criticality of fissile materials. Testing with actual waste was needed to determine the extent of iron and fissile isotope dissolution during Chemical Process Cell (CPC) processing. The Alternate Reductant Project was initiated by the Savannah River Remediation (SRR) Company to explore options for the replacement of the nitric-formic flowsheet used for the CPC at the Defense Waste Processing Facility (DWPF). The goals of the Alternate Reductant Project are to reduce CPC cycle time, increase mass throughput of the facility, and reduce operational hazards. In order to achieve these goals, several different reductants were considered during initial evaluations conducted by Savannah River National Laboratory (SRNL). After review of the reductants by SRR, SRNL, and Energy Solutions (ES) Vitreous State Laboratory (VSL), two flowsheets were further developed in parallel. The two flowsheet options included a nitric-formic-glycolic flowsheet, and a nitric-formic-sugar flowsheet. As of July 2011, SRNL and ES/VSL have completed the initial flowsheet development work for the nitric-formic-glycolic flowsheet and nitric-formic-sugar flowsheet, respectively. On July 12th and July 13th, SRR conducted a Systems Engineering Evaluation (SEE) to down select the alternate reductant flowsheet. The SEE team selected the Formic-Glycolic Flowsheet for further development. Two risks were identified in SEE for expedited research. The first risk is related to iron and plutonium solubility during the CPC process with respect to criticality. Currently, DWPF credits iron as a poison for the fissile components of the sludge. Due to the high iron solubility observed during the flowsheet demonstrations with simulants, it was necessary to determine if the plutonium in the radioactive sludge slurry

  18. DWPF FLOWSHEET STUDIES WITH SIMULANT TO DETERMINE THE IMPACT OF NEXT GENERATION SOLVENT ON THE CPC PROCESS AND GLASS FORMULATION

    SciTech Connect

    Newell, J.; Peeler, D.; Edwards, T.; Hay, M.; Stone, M.

    2011-06-29

    As a part of the Actinide Removal Process (ARP)/Modular Caustic Side Solvent Extraction Unit (MCU) Life Extension Project, a next generation solvent (NGS), a new strip acid, and modified monosodium titanate (mMST) will be deployed. The NGS is comprised of four components: 0.050 M MaxCalix (extractant), 0.50 M Cs-7SB (modifier), 0.003 M guanidine-LIX-79, with the balance ({approx}74 wt%) being Isopar{reg_sign} L. The strip acid will be changed from dilute nitric acid to dilute boric acid (0.01 M). Because of these changes, experimental testing with the next generation solvent and mMST was required to determine the impact of these changes in 512-S and Defense Waste Processing Facility (DWPF) operations, as well as Chemical Process Cell (CPC), glass formulation activities, and melter operations. Because of these changes, experimental testing with the next generation solvent and mMST is required to determine the impact of these changes. A Technical Task Request (TTR) was issued to support the assessments of the impact of the next generation solvent and mMST on the downstream DWPF flowsheet unit. The TTR identified five tasks to be investigated: (1) CPC Flowsheet Demonstration for NGS; (2) Solvent Stability for DWPF CPC Conditions; (3) Glass Formulation Studies; (4) Boron Volatility and Melt Rate; and (5) CPC Flowsheet Demonstration for mMST.

  19. Flowsheet development studies for the decontamination of high-activity-level water at Three Mile Island Unit 2

    SciTech Connect

    Collins, E.D.; Bigelow, J.E.; Campbell, D.O.; King, L.J.; Knauer, J.B.

    1980-01-01

    Several chemical processing flowsheets were considered for the decontamination of high-activity-level water at the Three Mile Island (TMI) Unit 2. A zeolite ion exchange process was evaluated and recommended for absorption of the bulk of the highly radioactive cesium and strontium. Standard organic ion-exchange resins were selected to remove the remaining traces of radioactive nuclides (except tritium which cannot be removed by any practical process). Process conditions were evaluated using both synthetic, tracer-level solutions and samples of actual, high-activity level water from TMI Unit 2.

  20. 'GREENER' CHEMICAL SYNTHESES USING ALTERNATE REACTION CONDITIONS

    EPA Science Inventory

    Microwave (MW) irradiation in conjunction with water as reaction media has proven to be a greener chemical approach for expeditious N-alkylation reactions of amines and hydrazines wherein the reactions under mildly basic conditions afford tertiary amines and double N-alkylation t...

  1. Key results from SB8 simulant flowsheet studies

    SciTech Connect

    Koopman, D. C.

    2013-04-26

    Key technically reviewed results are presented here in support of the Defense Waste Processing Facility (DWPF) acceptance of Sludge Batch 8 (SB8). This report summarizes results from simulant flowsheet studies of the DWPF Chemical Process Cell (CPC). Results include: Hydrogen generation rate for the Sludge Receipt and Adjustment Tank (SRAT) and Slurry Mix Evaporator (SME) cycles of the CPC on a 6,000 gallon basis; Volume percent of nitrous oxide, N2O, produced during the SRAT cycle; Ammonium ion concentrations recovered from the SRAT and SME off-gas; and, Dried weight percent solids (insoluble, soluble, and total) measurements and density.

  2. Flowsheets and source terms for radioactive waste projections

    SciTech Connect

    Forsberg, C.W.

    1985-03-01

    Flowsheets and source terms used to generate radioactive waste projections in the Integrated Data Base (IDB) Program are given. Volumes of each waste type generated per unit product throughput have been determined for the following facilities: uranium mining, UF/sub 6/ conversion, uranium enrichment, fuel fabrication, boiling-water reactors (BWRs), pressurized-water reactors (PWRs), and fuel reprocessing. Source terms for DOE/defense wastes have been developed. Expected wastes from typical decommissioning operations for each facility type have been determined. All wastes are also characterized by isotopic composition at time of generation and by general chemical composition. 70 references, 21 figures, 53 tables.

  3. SLUDGE BATCH 6 PHASE II FLOWSHEET SIMULATIONS

    SciTech Connect

    Koopman, D.; Best, D.

    2010-03-30

    Two Sludge Receipt and Adjustment Tank (SRAT) runs were used to demonstrate that a fairly wide window of acid stoichiometry was available for processing SB6 Phase II flowsheet simulant (Tank 40 simulant) while still meeting the dual goals of acceptable nitrate destruction and controlled hydrogen generation. Phase II was an intermediate flowsheet study for the projected composition of Tank 40 after transfer of SB6/Tank 51 sludge to the heel of SB5. The composition was based on August 2009 projections. A window of about 50% in total acid was found between acceptable nitrite destruction and excessive hydrogen generation.

  4. Formic Acid Free Flowsheet Development To Eliminate Catalytic Hydrogen Generation In The Defense Waste Processing

    SciTech Connect

    Lambert, Dan P.; Stone, Michael E.; Newell, J. David; Fellinger, Terri L.; Bricker, Jonathan M.

    2012-09-14

    The Defense Waste Processing Facility (DWPF) processes legacy nuclear waste generated at the Savannah River Site (SRS) during production of plutonium and tritium demanded by the Cold War. The nuclear waste is first treated via a complex sequence of controlled chemical reactions and then vitrified into a borosilicate glass form and poured into stainless steel canisters. Converting the nuclear waste into borosilicate glass canisters is a safe, effective way to reduce the volume of the waste and stabilize the radionuclides. Testing was initiated to determine whether the elimination of formic acid from the DWPF's chemical processing flowsheet would eliminate catalytic hydrogen generation. Historically, hydrogen is generated in chemical processing of alkaline High Level Waste sludge in DWPF. In current processing, sludge is combined with nitric and formic acid to neutralize the waste, reduce mercury and manganese, destroy nitrite, and modify (thin) the slurry rheology. The noble metal catalyzed formic acid decomposition produces hydrogen and carbon dioxide. Elimination of formic acid by replacement with glycolic acid has the potential to eliminate the production of catalytic hydrogen. Flowsheet testing was performed to develop the nitric-glycolic acid flowsheet as an alternative to the nitric-formic flowsheet currently being processed at the DWPF. This new flowsheet has shown that mercury can be reduced and removed by steam stripping in DWPF with no catalytic hydrogen generation. All processing objectives were also met, including greatly reducing the Slurry Mix Evaporator (SME) product yield stress as compared to the baseline nitric/formic flowsheet. Ten DWPF tests were performed with nonradioactive simulants designed to cover a broad compositional range. No hydrogen was generated in testing without formic acid.

  5. Computer program developed for flowsheet calculations and process data reduction

    NASA Technical Reports Server (NTRS)

    Alfredson, P. G.; Anastasia, L. J.; Knudsen, I. E.; Koppel, L. B.; Vogel, G. J.

    1969-01-01

    Computer program PACER-65, is used for flowsheet calculations and easily adapted to process data reduction. Each unit, vessel, meter, and processing operation in the overall flowsheet is represented by a separate subroutine, which the program calls in the order required to complete an overall flowsheet calculation.

  6. Physical-chemical conditions of ore deposition

    USGS Publications Warehouse

    Barton, P.B., Jr.

    1981-01-01

    Ore deposits form under a wide range of physical and chemical conditions, but those precipitating from hot, aqueous fluids-i.e. the hydrothermal deposits-form generally below 700??C and at pressures of only 1 or 2 kbar or less. Natural aqueous fluids in rocks may extract metal and sulfur from a variety of rock types or may acquire them as a residual heritage from a crystallizing silicate magma. Ore-forming hydrothermal fluids never appear as hot springs (except in deep, submarine situations) because they boil, mix with surface waters, and cool, thereby losing their ore-bearing ability before reaching the surface. Mineral systems function as chemical buffers and indicators just as buffers and indicators function in a chemical laboratory. By reading the record written in the buffer/indicator assemblages of minerals one can reconstruct many aspects of the former chemical environment. By studying the record of changing conditions one may deduce information regarding the processes functioning to create the succession of chemical environments and the ore deposits they represent. The example of the OH vein at Creede, Colorado, shows a pH buffered by the K-feldspar + muscovite + quartz assemblage and the covariation of S2 and O2 buffered by the assemblage chlorite + pyrite + quartz. Boiling of the ore fluid led to its oxidation to hematite-bearing assemblages and simultaneously produced an intensely altered, sericitic capping over the vein in response to the condensation of vapors bearing acidic components. The solubility of metals as calculated from experimental and theoretical studies of mineral solubility appears too low by at least one or two powers of ten to explain the mineralization at Creede. In contrast to Creede where the mineral stabilities all point to a relatively consistent chemistry, the Mississippi Valley type deposits present a puzzle of conflicting chemical clues that are impossible to reconcile with any single equilibrium situation. Thus we must

  7. SLUDGE BATCH 5 SIMULANT FLOWSHEET STUDIES

    SciTech Connect

    Lambert, D; Michael Stone, M; Bradley Pickenheim, B; David Best, D; David Koopman, D

    2008-10-03

    The Defense Waste Processing Facility (DWPF) will transition from Sludge Batch 4 (SB4) processing to Sludge Batch 5 (SB5) processing in early fiscal year 2009. Tests were conducted using non-radioactive simulants of the expected SB5 composition to determine the impact of varying the acid stoichiometry during the Sludge Receipt and Adjustment Tank (SRAT) and Slurry Mix Evaporator (SME) processes. The work was conducted to meet the Technical Task Request (TTR) HLW/DWPF/TTR-2007-0007, Rev. 1 and followed the guidelines of a Task Technical and Quality Assurance Plan (TT&QAP). The flowsheet studies are performed to evaluate the potential chemical processing issues, hydrogen generation rates, and process slurry rheological properties as a function of acid stoichiometry. Initial SB5 flowsheet studies were conducted to guide decisions during the sludge batch preparation process. These studies were conducted with the estimated SB5 composition at the time of the study. The composition has changed slightly since these studies were completed due to changes in the washing plan to prepare SB5 and the estimated SB4 heel mass. Nine DWPF process simulations were completed in 4-L laboratory-scale equipment using both a batch simulant (Tank 51 simulant after washing is complete) and a blend simulant (Tank 40 simulant after Tank 51 transfer is complete). Each simulant had a set of four SRAT and SME simulations at varying acid stoichiometry levels (115%, 130%, 145% and 160%). One additional run was made using blend simulant at 130% acid that included additions of the Actinide Removal Process (ARP) waste prior to acid addition and the Modular Caustic Side Solvent Extraction (CSSX) Unit (MCU) waste following SRAT dewatering. There are several parameters that are noteworthy concerning SB5 sludge: (1) This is the first batch DWPF will be processing that contains sludge that has had a significant fraction of aluminum removed through aluminum dissolution. (2) The sludge is high in mercury

  8. Preliminary flowsheet for plasma arc calcination of selected Hanford tank waste

    SciTech Connect

    Hendrickson, D.W.

    1994-09-19

    This preliminary flowsheet document was developed for the Initial Pretreatment Module (IPM). This flowsheet documents the calcination technology that can be used to accomplish the destruction of organics, ferrocyanide, and nitrate/nitrite salts in addition to solubilizing aluminum compounds in selected waste tanks at the Hanford Site. The flow sheet conditions are 76 L/min diluted waste feed rate at 800{degrees}C, atmospheric pressure, and 100 millisecond residence time in the calciner. Preliminary flow diagrams, material balances, and energy requirements are presented.

  9. SLUDGE BATCH 4 SIMULANT FLOWSHEET STUDIES: PHASE II RESULTS

    SciTech Connect

    Stone, M; David Best, D

    2006-09-12

    The Defense Waste Processing Facility (DWPF) will transition from Sludge Batch 3 (SB3) processing to Sludge Batch 4 (SB4) processing in early fiscal year 2007. Tests were conducted using non-radioactive simulants of the expected SB4 composition to determine the impact of varying the acid stoichiometry during the Sludge Receipt and Adjustment Tank (SRAT) process. The work was conducted to meet the Technical Task Request (TTR) HLW/DWPF/TTR-2004-0031 and followed the guidelines of a Task Technical and Quality Assurance Plan (TT&QAP). The flowsheet studies are performed to evaluate the potential chemical processing issues, hydrogen generation rates, and process slurry rheological properties as a function of acid stoichiometry. Initial SB4 flowsheet studies were conducted to guide decisions during the sludge batch preparation process. These studies were conducted with the estimated SB4 composition at the time of the study. The composition has changed slightly since these studies were completed due to changes in the sludges blended to prepare SB4 and the estimated SB3 heel mass. The following TTR requirements were addressed in this testing: (1) Hydrogen and nitrous oxide generation rates as a function of acid stoichiometry; (2) Acid quantities and processing times required for mercury removal; (3) Acid quantities and processing times required for nitrite destruction; and (4) Impact of SB4 composition (in particular, oxalate, manganese, nickel, mercury, and aluminum) on DWPF processing (i.e. acid addition strategy, foaming, hydrogen generation, REDOX control, rheology, etc.).

  10. GLYCOLIC-FORMIC ACID FLOWSHEET SLUDGE MATRIX STUDY

    SciTech Connect

    Lambert, D.; Koopman, D.

    2011-06-30

    Testing was completed to demonstrate the viability of the newly developed glycolic acid/formic acid flowsheet on processing in the Defense Waste Processing Facility's (DWPF) Chemical Process Cell (CPC). The Savannah River National Laboratory (SRNL) initiated a sludge matrix study to evaluate the impact of changing insoluble solid composition on the processing characteristics of slurries in DWPF. Four sludge simulants were prepared to cover two compositional ranges in the waste. The first was high iron/low aluminum versus low iron/high aluminum (referred to as HiFe or LoFe in this report). The second was high calcium-manganese/low nickel, chromium, and magnesium versus low calcium-manganese/high nickel, chromium, and magnesium (referred to as HiMn or LoMn in this report). These two options can be combined to form four distinct sludge compositions. The sludge matrix study called for testing each of these four simulants near the minimum acid required for nitrite destruction (100% acid stoichiometry) and at a second acid level that produced significant hydrogen by noble metal catalyzed decomposition of formic acid (150% acid stoichiometry). Four simulants were prepared based on the four possible combinations of the Al/Fe and Mn-Ca/Mg-Ni-Cr options. Preliminary simulant preparation work has already been documented. The four simulants were used for high and low acid testing. Eight planned experiments (GF26 to GF33) were completed to demonstrate the viability of the glycolic-formic flowsheet. Composition and physical property measurements were made on the SRAT product. Composition measurements were made on the condensate from the Mercury Water Wash Tank (MWWT), Formic Acid Vent Condenser (FAVC), ammonia scrubber and on SRAT samples pulled throughout the SRAT cycle. Updated values for formate loss and nitrite-tonitrate conversion were found that can be used in the acid calculations for future sludge matrix process simulations with the glycolic acid/formic acid flowsheet

  11. FACILITATED CHEMICAL SYNTHESIS UNDER ALTERNATE REACTION CONDITIONS

    EPA Science Inventory

    The chemical research in the late 1990's witnessed a paradigm shift towards "environmentally-friendly chemistry" more popularly known as "green chemistry" due to the increasing environmental concerns and legislative requirements to curb the release of chemical waste into the atmo...

  12. GREEN CHEMICAL SYNTHESIS THROUGH CATALYSIS AND ALTERNATE REACTION CONDITIONS

    EPA Science Inventory

    Green chemical synthesis through catalysis and alternate reaction conditions

    Encompassing green chemistry techniques and methodologies, we have initiated several projects at the National Risk Management Research laboratory that focus on the design and development of chemic...

  13. DWPF RECYCLE EVAPORATOR FLOWSHEET EVALUATION (U)

    SciTech Connect

    Stone, M

    2005-04-30

    The Defense Waste Processing Facility (DWPF) converts the high level waste slurries stored at the Savannah River Site into borosilicate glass for long-term storage. The vitrification process results in the generation of approximately five gallons of dilute recycle streams for each gallon of waste slurry vitrified. This dilute recycle stream is currently transferred to the H-area Tank Farm and amounts to approximately 1,400,000 gallons of effluent per year. Process changes to incorporate salt waste could increase the amount of effluent to approximately 2,900,000 gallons per year. The recycle consists of two major streams and four smaller streams. The first major recycle stream is condensate from the Chemical Process Cell (CPC), and is collected in the Slurry Mix Evaporator Condensate Tank (SMECT). The second major recycle stream is the melter offgas which is collected in the Off Gas Condensate Tank (OGCT). The four smaller streams are the sample flushes, sump flushes, decon solution, and High Efficiency Mist Eliminator (HEME) dissolution solution. These streams are collected in the Decontamination Waste Treatment Tank (DWTT) or the Recycle Collection Tank (RCT). All recycle streams are currently combined in the RCT and treated with sodium nitrite and sodium hydroxide prior to transfer to the tank farm. Tank Farm space limitations and previous outages in the 2H Evaporator system due to deposition of sodium alumino-silicates have led to evaluation of alternative methods of dealing with the DWPF recycle. One option identified for processing the recycle was a dedicated evaporator to concentrate the recycle stream to allow the solids to be recycled to the DWPF Sludge Receipt and Adjustment Tank (SRAT) and the condensate from this evaporation process to be sent and treated in the Effluent Treatment Plant (ETP). In order to meet process objectives, the recycle stream must be concentrated to 1/30th of the feed volume during the evaporation process. The concentrated stream

  14. Sludge Batch 4 Simulant Flowsheet Studies with ARP and MCU: Impact of MCU Organics

    SciTech Connect

    Baich, M. A.; Herman, C. C.; Eibling, R. E.; Williams, M. F.; Smith, F. G.

    2005-07-01

    Two facilities for treating the salt currently being stored in the High Level Waste (HLW) tanks are currently planned to begin operations during the processing of Sludge Batch 4 (SB4). The Immobilization Technology Section (ITS) of the Savannah River National Laboratory (SRNL) was requested by the Defense Waste Processing Facility (DWPF) via Technical Task Request (TTR) HLW/DWPF/TTR-2004-0031 (Washburn, 2004) to evaluate the impacts on DWPF processing for streams from the Actinide Removal Process (ARP) and the Modular Caustic Side Solvent Side Extraction (CSSX) Unit (MCU). In particular, the TTR requests SRNL to validate the existing process flowsheet and establish a coupled operations flowsheet for use with SB4. The flowsheet runs are required so an evaluation of potential chemical processing issues, quantification of the potential hydrogen generation rates, and estimation of the required acid stoichiometry can be made. Previous testing (Baich et. al., 2003) was performed for incorporating ARP/MST in Sludge Batch 3 (SB3) and recommendations were made to DWPF on possible flowsheet options. However, since that time, some changes have occurred to the ARP facility processing strategy, and material balances have been revised (Subosits, 2004). Thus, testing with updated compositions was necessary. Since the MCU is a new design and project, no CPC flowsheet studies have been performed for this stream. This testing will validate the previously recommended ARP stream addition methods based on the new information and based on the need to also incorporate the MCU stream. The basic principle of solvent extraction is to use a sparingly soluble diluent material that carries an extractant that will complex with the cesium ions in the caustic HLW solution. The decontaminated aqueous stream (raffinate) is then sent to Saltstone for disposal. The cesium contained in the organic phase (solvent) can then be stripped into an aqueous phase ready for transfer to the DWPF. The solvent is

  15. Chemical disinfection under conditions of microgravity

    NASA Astrophysics Data System (ADS)

    Marchin, George L.

    1997-01-01

    There is enormous potential for point-of-use water purifiers where central water treatment does not exist or distribution systems are faulty and allow incursion of pathogenic organisms after primary treatment. Manned space missions on the Space Shuttle and planned missions on the Space Station also employ point-of-use water purifiers termed microbial check valves (MCVs). Polyiodide resin materials in use on the Space Shuttle within the MCV and in terrestrial water purifiers, silver and copper chelex resins, zirconium peroxide chelex resin, and a quaternary ammonium compound-Dow Corning 5700-polymerized to carbon and polystyrene beads, were compared for disinfection ability. Experiments were conducted in fluid processing apparatus (FPAs) at unit gravity and in microgravity conditions aboard seven STS missions. These new materials may have applications in both space and terrestrial water treatment devices.

  16. Modeling Flowsheet Data for Clinical Research.

    PubMed

    Johnson, Steven G; Byrne, Matthew D; Christie, Beverly; Delaney, Connie W; LaFlamme, Anne; Park, Jung In; Pruinelli, Lisiane; Sherman, Suzan G; Speedie, Stuart; Westra, Bonnie L

    2015-01-01

    Health care data included in clinical data repositories (CDRs) are increasingly used for quality reporting, business analytics and research; however, extended clinical data from interprofessional practice are seldom included. With the increasing emphasis on care coordination across settings, CDRs need to include data from all clinicians and be harmonized to understand the impact of their collaborative efforts on patient safety, effectiveness and efficiency. This study characterizes the extended clinical data derived from EHR flowsheet data that is available in the University of Minnesota's CDR and describes a process for creating an ontology that organizes that data so that it is more useful and accessible to researchers. The process is illustrated using a pressure ulcer ontology and compares ease of finding concepts in i2b2 for different data organization approaches. The challenges of the manual process and difficulties combining similar concepts are discussed. PMID:26306244

  17. Modeling Flowsheet Data for Clinical Research

    PubMed Central

    Johnson, Steven G.; Byrne, Matthew D.; Christie, Beverly; Delaney, Connie W.; LaFlamme, Anne; Park, Jung In; Pruinelli, Lisiane; Sherman, Suzan G.; Speedie, Stuart; Westra, Bonnie L.

    2015-01-01

    Health care data included in clinical data repositories (CDRs) are increasingly used for quality reporting, business analytics and research; however, extended clinical data from interprofessional practice are seldom included. With the increasing emphasis on care coordination across settings, CDRs need to include data from all clinicians and be harmonized to understand the impact of their collaborative efforts on patient safety, effectiveness and efficiency. This study characterizes the extended clinical data derived from EHR flowsheet data that is available in the University of Minnesota’s CDR and describes a process for creating an ontology that organizes that data so that it is more useful and accessible to researchers. The process is illustrated using a pressure ulcer ontology and compares ease of finding concepts in i2b2 for different data organization approaches. The challenges of the manual process and difficulties combining similar concepts are discussed. PMID:26306244

  18. GLYCOLIC-FORMIC ACID FLOWSHEET FINAL REPORT FOR DOWNSELECTION DECISION

    SciTech Connect

    Lambert, D.; Pickenheim, B.; Stone, M.; Newell, J.; Best, D.

    2011-03-10

    Flowsheet testing was performed to develop the nitric-glycolic-formic acid flowsheet (referred to as the glycolic-formic flowsheet throughout the rest of the report) as an alternative to the nitric/formic flowsheet currently being processed at the DWPF. This new flowsheet has shown that mercury can be removed in the Sludge Receipt and Adjustment Tank (SRAT) with minimal hydrogen generation. All processing objectives were also met, including greatly reducing the Slurry Mix Evaporator (SME) product yield stress as compared to the baseline nitric/formic flowsheet. Forty-six runs were performed in total, including the baseline run and the melter feed preparation runs. Significant results are summarized. The baseline nitric/formic flowsheet run, using the SB6 simulant produced by Harrell was extremely difficult to process successfully under existing DWPF acceptance criteria with this simulant at the HM levels of noble metals. While nitrite was destroyed and mercury was removed to near the DWPF limit, the rheology of the SRAT and SME products were well above design basis and hydrogen generation far exceeded the DWPF SRAT limit. In addition, mixing during the SME cycle was very poor. In this sense, the nitric/glycolic/formic acid flowsheet represents a significant upgrade over the current flowsheet. Mercury was successfully removed with almost no hydrogen generation and the SRAT and SME products yield stresses were within process limits or previously processed ranges. The glycolic-formic flowsheet has a very wide processing window. Testing was completed from 100% to 200% of acid stoichiometry and using a glycolic-formic mixture from 40% to 100% glycolic acid. The testing met all processing requirements throughout these processing windows. This should allow processing at an acid stoichiometry of 100% and a glycolic-formic mixture of 80% glycolic acid with minimal hydrogen generation. It should also allow processing endpoints in the SRAT and SME at significantly higher

  19. Demonstration of a SREX flowsheet for the partitioning of strontium and lead from actual ICPP sodium-bearing waste

    SciTech Connect

    Law, J.D.; Wood, D.J.; Olson, L.G.; Todd, T.A.

    1997-08-01

    Laboratory experimentation has indicated that the SREX process is effective for partitioning {sup 90}Sr and Pb from acidic radioactive waste solutions located at the Idaho Chemical Processing Plant. Previous countercurrent flowsheet testing of the SREX process with simulated waste resulted in 99.98% removal of Sr and 99.9% removal of Pb. Based on the results of these studies, a demonstration of the SREX flowsheet was performed. The demonstration consisted of (1) countercurrent flowsheet testing of the SREX process using simulated sodium-bearing waste spiked with {sup 85}Sr and (2) countercurrent flowsheet testing of the SREX process using actual waste from tank WM-183. All testing was performed using 24 stages of 2-cm diameter centrifugal contactors which are installed in the Remote Analytical Laboratory hot cell. The flowsheet tested consisted of an extraction section (0. 15 M 4`,4`(5)-di-(tert-butyldicyclohexo)-18-crown-6 and 1.5 M TBP in Isopar-L{reg_sign}), a 2.0 MHNO{sub 3} scrub section to remove extracted K from the SREX solvent, a 0.05 M HNO{sub 3} strip section for the removal of Sr from the SREX solvent, a 0.1 M ammonium citrate strip section for the removal of Pb from the SREX solvent, and a 3.0 M HNO{sub 3} equilibration section. The behavior of {sup 90}Sr, Pb, Na, K, Hg, H{sup +}, the actinides, and numerous other non-radioactive elements was evaluated. The described flowsheet successfully extracted and selectively stripped Sr and Ph from the SBW simulant and the actual tank waste. For the testing with actual tank waste (WM - 183), removal efficiencies of 99.995 % and >94% were obtained for {sup 90}Sr and Pb, respectively.

  20. Parametric study of complex distillation flowsheets for the separations of five-component mixtures

    SciTech Connect

    Rong, B.G.; Zheng, S.Q.; Zhou, C.G.

    1996-12-31

    Twenty two distillation flowsheets are studied for the separations of five-component mixtures based on the energy consumption and the annual costs. Fourteen flowsheets with simple columns and eight flowsheets with complex columns of side strippers and/or side rectifiers are included. Several five-component mixtures are selected, for various cases of feed composition distribution, the costs of the flowsheets are calculated and compared. Several heuristics are produced for the synthesis of distillation flowsheets with complex columns.

  1. 49 CFR 219.11 - General conditions for chemical tests.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false General conditions for chemical tests. 219.11 Section 219.11 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD... for chemical tests. (a) Any employee who performs covered service for a railroad is deemed to...

  2. 49 CFR 219.11 - General conditions for chemical tests.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 4 2014-10-01 2014-10-01 false General conditions for chemical tests. 219.11 Section 219.11 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD... for chemical tests. (a) Any employee who performs covered service for a railroad is deemed to...

  3. 49 CFR 219.11 - General conditions for chemical tests.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 4 2012-10-01 2012-10-01 false General conditions for chemical tests. 219.11 Section 219.11 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD... for chemical tests. (a) Any employee who performs covered service for a railroad is deemed to...

  4. 49 CFR 219.11 - General conditions for chemical tests.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 4 2011-10-01 2011-10-01 false General conditions for chemical tests. 219.11 Section 219.11 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD... for chemical tests. (a) Any employee who performs covered service for a railroad is deemed to...

  5. 49 CFR 219.11 - General conditions for chemical tests.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 4 2013-10-01 2013-10-01 false General conditions for chemical tests. 219.11 Section 219.11 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD... for chemical tests. (a) Any employee who performs covered service for a railroad is deemed to...

  6. FRACTIONAL CRYSTALLIZATION FLOWSHEET TESTS WITH ACTUAL TANK WASTE

    SciTech Connect

    HERTING, D.L.

    2006-10-18

    Laboratory-scale flowsheet tests of the fractional crystallization process were conducted with actual tank waste samples in a hot cell at the 222-S Laboratory. The process is designed to separate medium-curie liquid waste into a low-curie stream for feeding to supplemental treatment and a high-curie stream for double-shell tank storage. Separations criteria (for Cs-137 sulfate, and sodium) were exceeded in all three of the flowsheet tests that were performed.

  7. FRACTIONAL CRYSTALLIZATION FLOWSHEET TESTS WITH ACTUAL TANK WASTE

    SciTech Connect

    HERTING, D.L.

    2007-04-13

    Laboratory-scale flowsheet tests of the fractional crystallization process were conducted with actual tank waste samples in a hot cell at the 2224 Laboratory. The process is designed to separate medium-curie liquid waste into a low-curie stream for feeding to supplemental treatment and a high-curie stream for double-shell tank storage. Separations criteria (for Cesium-137 sulfate and sodium) were exceeded in all three of the flowsheet tests that were performed.

  8. Possible interrelations among chemical freeze-out conditions

    NASA Astrophysics Data System (ADS)

    Tawfik, A.; El-Bakry, M. Y.; Habashy, D. M.; Mohamed, M. T.; Abbas, E.

    2016-03-01

    At thermal equilibrium, different chemical freeze-out conditions have been proposed so far. They have an ultimate aim of proposing a universal description for the chemical freeze-out parameters (Tch and μb), which are to be extracted from the statistical fitting of different particle ratios measured at various collision energies with calculations from thermal models. A systematic comparison between these conditions is presented. The physical meaning of each of them and their sensitivity to the hadron mass cuts are discussed. Based on availability, some of them are compared with recent lattice calculations. We found that most of these conditions are thermodynamically equivalent, especially at small baryon chemical potential. We propose that further crucial consistency tests should be performed at low energies. The fireball thermodynamics is another way of guessing conditions describing the chemical freeze-out parameters extracted from high-energy experiments. We endorse the possibility that the various chemical freeze-out conditions should be interpreted as different aspects of one universal condition.

  9. Validity conditions for moment closure approximations in stochastic chemical kinetics

    SciTech Connect

    Schnoerr, David; Sanguinetti, Guido; Grima, Ramon

    2014-08-28

    Approximations based on moment-closure (MA) are commonly used to obtain estimates of the mean molecule numbers and of the variance of fluctuations in the number of molecules of chemical systems. The advantage of this approach is that it can be far less computationally expensive than exact stochastic simulations of the chemical master equation. Here, we numerically study the conditions under which the MA equations yield results reflecting the true stochastic dynamics of the system. We show that for bistable and oscillatory chemical systems with deterministic initial conditions, the solution of the MA equations can be interpreted as a valid approximation to the true moments of the chemical master equation, only when the steady-state mean molecule numbers obtained from the chemical master equation fall within a certain finite range. The same validity criterion for monostable systems implies that the steady-state mean molecule numbers obtained from the chemical master equation must be above a certain threshold. For mean molecule numbers outside of this range of validity, the MA equations lead to either qualitatively wrong oscillatory dynamics or to unphysical predictions such as negative variances in the molecule numbers or multiple steady-state moments of the stationary distribution as the initial conditions are varied. Our results clarify the range of validity of the MA approach and show that pitfalls in the interpretation of the results can only be overcome through the systematic comparison of the solutions of the MA equations of a certain order with those of higher orders.

  10. Development of the flowsheet used for decontaminating high-activity-level water at TMI-2. Draft

    SciTech Connect

    Collins, E.D.; Campbell, D.O.; King, L.J.; Knauer, J.B.; Wallace, R.M.

    1985-01-01

    Using a few small samples of high-activity-level water from TMI-2, a chemical processing flowsheet was developed for decontamination of the water and concentration of the radioactive contaminants in a form suitable for disposal. The initially selected process was evaluated and significantly improved. The improved process included sorption of the bulk radioactive materials, cesium and strontium, onto a mixture of inorganic zeolites and sorption of the anionic contaminants, antimony and ruthenium, plus the remaining traces of cesium and strontium onto standard organic ion exchange resins. The latter step was accomplished by means of a special deionization/sorption technique.

  11. Evaluating Process Sustainability Using Flowsheet Monitoring (Abstract)

    EPA Science Inventory

    Environmental metric software can be used to evaluate the sustainability of a chemical based upon data from the chemical process that is used to manufacture it. One problem in developing environmental metric software is that chemical process simulation packages typically do not p...

  12. Evaluating Process Sustainability Using Flowsheet Monitoring

    EPA Science Inventory

    Environmental metric software can be used to evaluate the sustainability of a chemical based on data from the chemical process that is used to manufacture it. One problem in developing environmental metric software is that chemical process simulation packages typically do not rea...

  13. SRNL report for the tank waste disposition integrated flowsheet: Corrosion testing

    SciTech Connect

    Wyrwas, R. B.

    2015-09-30

    A series of cyclic potentiodynamic polarization (CPP) tests were performed in support of the Tank Waste Disposition Integrated Flowsheet (TWDIF). The focus of the testing was to assess the effectiveness of the SRNL model for predicting the amount of nitrite inhibitor needed to prevent pitting induced by increasing halide concentrations. The testing conditions were selected to simulate the dilute process stream that is proposed to be returned to tank farms from treating the off-gas from the low activity waste melter in the Waste Treatment and Immobilization Plant.

  14. Fate of hydraulic fracturing chemicals under down-hole conditions

    NASA Astrophysics Data System (ADS)

    Blotevogel, J.; Kahrilas, G.; Corrin, E. R.; Borch, T.

    2013-12-01

    Hydraulic fracturing is a method to increase the yield of oil and natural gas extraction from unconventional rock formations. The process of hydrofracturing occurs via injecting water, sand, and chemicals into the production well and subjecting this mixture to high pressures to crack the rock shale, allowing increased amounts of gas and oil to seep out of the target formation. Typical constituents of the chemical mixtures are biocides, which are applied to inhibit growth of sulfate reducing bacteria in order to prevent pipe corrosion and production of hazardous gases. However, very little is known about the persistence, fate, and activity of biocides when subjected to the high temperatures and pressures of down-hole conditions. Thus, the objective of this talk is to present data from ongoing experiments focused on determining the fate of biocides commonly used for hydraulic fracturing under conditions simulating down-hole environments. Using stainless steel reactors, the high pressures and temperatures of down-hole conditions in the Marcellus shale are simulated, while concentration, speciation, and degradation of priority biocides are observed as a function of time, using primarily LC/MS techniques. The impact of water quality, shale, temperature, and pressure on the transformation kinetics and pathways of biocides will be discussed. Finally, field samples (both sediments and flowback brine) from the Marcellus shale are analyzed to verify that our lab simulations mirror real-life conditions and results.

  15. Chemically induced compaction bands: Triggering conditions and band thickness

    NASA Astrophysics Data System (ADS)

    Stefanou, Ioannis; Sulem, Jean

    2014-02-01

    During compaction band formation, various mechanisms can be involved at different scales. Mechanical and chemical degradation of the solid skeleton and grain damage are important factors that may trigger instabilities in the form of compaction bands. Here we explore the conditions of compaction band formation in quartz- and carbonate-based geomaterials by considering the effect of chemical dissolution and grain breakage. As the stresses/deformations evolve, the grains of the material break, leading to an increase of their specific surface. Consequently, their dissolution is accelerated and chemical softening is triggered. By accounting for (a) the mass diffusion of the system, (b) a macroscopic failure criterion with dissolution softening, and (c) the reaction kinetics at the microlevel, a model is proposed and the conditions for compaction instabilities are investigated. Distinguishing the microscale (grain level) from the macrolevel (representative elementary volume) and considering the heterogeneous microstructure of the representative elementary volume, it is possible to discuss the thickness and periodicity of compaction bands. Two case studies are investigated. The first one concerns a sandstone rock reservoir which is water flooded and the second one a carbonate rock in which CO2 is injected for storage. It is shown that compaction band instabilities are possible in both cases.

  16. MELTER OFF-GAS FLAMMABILITY ASSESSMENT FOR DWPF ALTERNATE REDUCTANT FLOWSHEET OPTIONS

    SciTech Connect

    Choi, A.

    2011-07-08

    Glycolic acid and sugar are being considered as potential candidates to substitute for much of the formic acid currently being added to the Defense Waste Processing Facility (DWPF) melter feed as a reductant. A series of small-scale melter tests were conducted at the Vitreous State Laboratory (VSL) in January 2011 to collect necessary data for the assessment of the impact of these alternate reductants on the melter off-gas flammability. The DM10 melter with a 0.021 m{sup 2} melt surface area was run with three different feeds which were prepared at SRNL based on; (1) the baseline formic/nitric acid flowsheet, (2) glycolic/formic/nitric acid flowsheet, and (3) sugar/formic/nitric acid flowsheet - these feeds will be called the baseline, glycolic, and sugar flowsheet feeds, respectively, hereafter. The actual addition of sugar to the sugar flowsheet feed was made at VSL before it was fed to the melter. For each feed, the DM10 was run under both bubbled (with argon) and non-bubbled conditions at varying melter vapor space temperatures. The goal was to lower its vapor space temperature from nominal 500 C to less than 300 C at 50 C increments and maintain steady state at each temperature at least for one hour, preferentially for two hours, while collecting off-gas data including CO, CO{sub 2}, and H{sub 2} concentrations. Just a few hours into the first test with the baseline feed, it was discovered that the DM10 vapor space temperature would not readily fall below 350 C simply by ramping up the feed rate as the test plan called for. To overcome this, ambient air was introduced directly into the vapor space through a dilution air damper in addition to the natural air inleakage occurring at the operating melter pressure of -1 inch H{sub 2}O. A detailed description of the DM10 run along with all the data taken is given in the report issued by VSL. The SRNL personnel have analyzed the DM10 data and identified 25 steady state periods lasting from 32 to 92 minutes for all

  17. Physical beneficiation of char and chemically conditioned coal

    SciTech Connect

    Warzinski, R.P.; Cavallaro, J.A.

    1986-04-01

    Demineralization of coals and coal-derived chars is part of an effort to develop alternative fuels from coal. Pyrolysis and some gasification processes yield chars containing a large fraction of the calorific value of the feed coal and essentially all of its mineral matter. In the work reported here, three gasification chars produced from anthracite, bituminous, and subbituminous coals have been subjected to specific gravity separation to determine their yield-ash relationships. Either low yields or high ash levels in the float products were observed. Also reported is preliminary work concerning the use of chemical conditioning to enhance the cleanability of coal prior to physical beneficiation. Conditioning of an Illinois No. 6 River King Mine coal with either supercritical methanol or cyclohexane resulted in an improved yield-ash relationship, whereas similar treatment with supercritical toluene had a negative effect.

  18. HYBRID SULFUR FLOWSHEETS USING PEM ELECTROLYSIS AND A BAYONET DECOMPOSITION REACTOR

    SciTech Connect

    Gorensek, M; William Summers, W

    2008-05-30

    A conceptual design is presented for a Hybrid Sulfur process for the production of hydrogen using a high-temperature nuclear heat source to split water. The process combines proton exchange membrane-based SO{sub 2}-depolarized electrolyzer technology being developed at Savannah River National Laboratory with silicon carbide bayonet decomposition reactor technology being developed at Sandia National Laboratories. Both are part of the US DOE Nuclear Hydrogen Initiative. The flowsheet otherwise uses only proven chemical process components. Electrolyzer product is concentrated from 50 wt% sulfuric acid to 75 wt% via recuperative vacuum distillation. Pinch analysis is used to predict the high-temperature heat requirement for sulfuric acid decomposition. An Aspen Plus{trademark} model of the flowsheet indicates 340.3 kJ high-temperature heat, 75.5 kJ low-temperature heat, 1.31 kJ low-pressure steam, and 120.9 kJ electric power are consumed per mole of H{sub 2} product, giving an LHV efficiency of 35.3% (41.7% HHV efficiency) if electric power is available at a conversion efficiency of 45%.

  19. Hydrogen generation in SRAT with nitric acid and late washing flowsheets. Summary report

    SciTech Connect

    Hsu, C.W.

    1992-10-22

    Melter feed preparation processes, incorporating a final wash of the precipitate slurry feed to Defense Waste Processing Facility (DWPF) and a partial substitution of the SRAT formic acid requirement with nitric acid, should not produce peak hydrogen generation rates during Cold Chemical Runs (CCR`s) and radioactive operation greater than their current, respective hydrogen design bases of 0.024 lb/hr and 1.5 lb/hr. A single SRAT bench-scale process simulation for CCR-s produced a DWPF equivalent peak hydrogen generation rate of 0.004 lb/hr. During radioactive operation, the peak hydrogen generation rate will be dependent on the extent DWPF deviates from the nominal precipitate hydrolysis and melter feed preparation process operating parameters. Two actual radioactive sludges were treated according to the new flowsheets. The peak hydrogen evolution rates were equivalent to 0.038 and 0.20 lb/hr (DWPF scale) respectively. Compared to the formic acid -- HAN hydrolysis flowsheets, these peak rates were reduced by a factor of 2.5 and 3.4 for Tank 15 and Tank 11 sludges, respectively.

  20. Hydrogen generation in SRAT with nitric acid and late washing flowsheets

    SciTech Connect

    Hsu, C.W.

    1992-10-22

    Melter feed preparation processes, incorporating a final wash of the precipitate slurry feed to Defense Waste Processing Facility (DWPF) and a partial substitution of the SRAT formic acid requirement with nitric acid, should not produce peak hydrogen generation rates during Cold Chemical Runs (CCR's) and radioactive operation greater than their current, respective hydrogen design bases of 0.024 lb/hr and 1.5 lb/hr. A single SRAT bench-scale process simulation for CCR-s produced a DWPF equivalent peak hydrogen generation rate of 0.004 lb/hr. During radioactive operation, the peak hydrogen generation rate will be dependent on the extent DWPF deviates from the nominal precipitate hydrolysis and melter feed preparation process operating parameters. Two actual radioactive sludges were treated according to the new flowsheets. The peak hydrogen evolution rates were equivalent to 0.038 and 0.20 lb/hr (DWPF scale) respectively. Compared to the formic acid -- HAN hydrolysis flowsheets, these peak rates were reduced by a factor of 2.5 and 3.4 for Tank 15 and Tank 11 sludges, respectively.

  1. ALTERNATIVE FLOWSHEETS FOR THE SULFUR-IODINE THERMOCHEMICAL HYDROGEN CYCLE

    SciTech Connect

    BROWN,LC; LENTSCH,RD; BESENBRUCH,GE; SCHULTZ,KR; FUNK,JE

    2003-02-01

    OAK-B135 A hydrogen economy will need significant new sources of hydrogen. Unless large-scale carbon sequestration can be economically implemented, use of hydrogen reduces greenhouse gases only if the hydrogen is produced with non-fossil energy sources. Nuclear energy is one of the limited options available. One of the promising approaches to produce large quantities of hydrogen from nuclear energy efficiently is the Sulfur-Iodine (S-I) thermochemical water-splitting cycle, driven by high temperature heat from a helium Gas-Cooled Reactor. They have completed a study of nuclear-driven thermochemical water-splitting processes. The final task of this study was the development of a flowsheet for a prototype S-I production plant. An important element of this effort was the evaluation of alternative flowsheets and selection of the reference design.

  2. DWPF FLOWSHEET STUDIES WITH SIMULANTS TO DETERMINE MCU SOLVENT BUILD-UP IN CONTINOUS RUNS

    SciTech Connect

    Lambert, D; Frances Williams, F; S Crump, S; Russell Eibling, R; Thomas02 White, T; David Best, D

    2006-05-25

    The Actinide Removal Process (ARP) facility and the Modular Caustic Side Solvent Extraction Unit (MCU) are scheduled to begin processing salt waste in fiscal year 2007. A portion of the streams generated in these salt processing facilities will be transferred to the Defense Waste Processing Facility (DWPF) to be incorporated in the glass matrix. Before the streams are introduced, a combination of impact analyses and research and development studies must be performed to quantify the impacts on DWPF processing. The Process Science & Engineering (PS&E) section of the Savannah River National Laboratory (SRNL) was requested via Technical Task Request (TTR) HLW/DWPF/TTR-2004-0031 to evaluate the impacts on DWPF processing. Simulant Chemical Process Cell (CPC) flowsheet studies have been performed using previous composition and projected volume estimates for the ARP sludge/monosodium titanate (MST) stream. Initial MCU incorporation testing for the DWPF flowsheet indicated unacceptable levels of Isopar{reg_sign}L were collecting in the Sludge Receipt and Adjustment Tank (SRAT) condenser system and unanticipated quantities of modifier were carrying over into the SRAT condenser system. This work was performed as part of Sludge Batch 4 (SB4) flowsheet testing and was reported by Baich et al. Due to changes in the flammability control strategy for DWPF for salt processing, the incorporation strategy for ARP changed and additional ARP flowsheet tests were necessary to validate the new processing strategy. The last round of ARP testing included the incorporation of the MCU stream and identified potential processing issues with the MCU solvent. The identified issues included the potential carry-over and accumulation of the MCU solvent components in the CPC condensers and in the recycle stream to the Tank Farm. Solvent retention in the DWPF condensers contradicts the DWPF solvent control strategy. Therefore, DWPF requested SRNL to perform additional MCU flowsheet studies to better

  3. Neptunium flow-sheet verification at reprocessing plants

    SciTech Connect

    Rance, P.; Chesnay, B.; Killeen, T.; Murray, M.; Nikkinen, M.; Petoe, A.; Plumb, J.; Saukkonen, H.

    2007-07-01

    Due to their fissile nature, neptunium and americium have at least a theoretical potential application as nuclear explosives and their proliferation potential was considered by the IAEA in studies in the late 1990's. This work was motivated by an increased awareness of the proliferation potential of americium and neptunium and a number of emerging projects in peaceful nuclear programmes which could result in an increase in the available quantities of these minor actinides. The studies culminated in proposals for various voluntary measures including the reporting of international transfers of separated americium and neptunium, declarations concerning the amount of separated neptunium and americium held by states and the application of flow-sheet verification to ensure that facilities capable of separating americium or neptunium are operated in a manner consistent with that declared. This paper discusses the issue of neptunium flowsheet verification in reprocessing plants. The proliferation potential of neptunium is first briefly discussed and then the chemistry of neptunium relevant to reprocessing plants described with a view to indicating a number of issues relevant to the verification of neptunium flow-sheets. Finally, the scope of verification activities is discussed including analysis of process and engineering design information, plant monitoring and sampling and the potential application of containment and surveillance measures. (authors)

  4. Sasse Modeling of First Cycle Neptunium (VI) Recovery Flowsheet

    SciTech Connect

    Laurinat, J. E.

    2006-04-01

    A flowsheet has been proposed to separate neptunium from solutions in H-Canyon Tanks 16.4, 12.5, and 11.7 in the First Cycle solvent extraction banks, in which cerium(IV) (Ce(IV)) serves as an agent to oxidize neptunium to neptunium(VI) (Np(VI)). A SASSE (Spreadsheet Algorithm for Stagewise Solvent Extraction) spreadsheet model indicates that the proposed flowsheet is a feasible method for separating neptunium and uranium from sulfates, thorium, and other metal impurities. The proposed flowsheet calls for stripping the sulfates, thorium, and other metal impurities into the 1AW stream and extracting and then stripping the neptunium and uranium into the 1BP stream. SASSE predicts that separation of thorium from the other actinides can be accomplished with actinide losses of 0.01% or less. It is assumed that other metal impurities such as iron, aluminum, and fission products will follow the thorium into 1AW. Due to an organic/aqueous distribution coefficient that is close to one, SASSE predicts that plutonium(VI) (Pu(VI)) is split between the A Bank and B Bank aqueous output streams, with 27% going to 1AW and 73% going to 1BP. An extrapolated distribution coefficient based on unvalidated Ce(IV) distribution measurements at a single nitrate concentration and a comparison with thorium(IV) (Th(IV)) distributions indicates that Ce(IV) could reflux in 1B Bank. If the Ce(IV) distribution coefficient is lower than would be predicted by this single point extrapolation, but still higher than the distribution coefficient for Th(IV), then Ce(IV) would follow Np(VI) and uranium(VI) (U(VI)) into 1BP. The SASSE model was validated using data from a 1964 oxidizing flowsheet for the recovery of Np(VI) in Second Cycle. For the proposed flowsheet to be effective in recovering neptunium, the addition of approximately 0.025 M ceric ammonium nitrate (Ce(NH4)2(NO3)6) to both the 1AF and 1AS streams is required to stabilize the neptunium in the +6

  5. CHEMICAL SYNTHESIS USING 'GREENER' ALTERNATIVE REACTION CONDITIONS AND MEDIA

    EPA Science Inventory

    The chemical research during the last decade has witnessed a paradigm shift towards "environmentally-friendly chemistry" more popularly known as "green chemistry" due to the increasing environmental concerns and legislative requirements to curb the release of chemical waste into ...

  6. Development of the high-level waste high-temperature melter feed preparation flowsheet for vitrification process testing

    SciTech Connect

    Seymour, R.G.

    1995-02-17

    High-level waste (HLW) feed preparation flowsheet development was initiated in fiscal year (FY) 1994 to evaluate alternative flowsheets for preparing melter feed for high-temperature melter (HTM) vitrification testing. Three flowsheets were proposed that might lead to increased processing capacity relative to the Hanford Waste Vitrification Plant (HWVP) and that were flexible enough to use with other HLW melter technologies. This document describes the decision path that led to the selection of flowsheets to be tested in the FY 1994 small-scale HTM tests. Feed preparation flowsheet development for the HLW HTM was based on the feed preparation flowsheet that was developed for the HWVP. This approach allowed the HLW program to build upon the extensive feed preparation flowsheet database developed under the HWVP Project. Primary adjustments to the HWVP flowsheet were to the acid adjustment and glass component additions. Developmental background regarding the individual features of the HLW feed preparation flowsheets is provided. Applicability of the HWVP flowsheet features to the new HLW vitrification mission is discussed. The proposed flowsheets were tested at the laboratory-scale at Pacific Northwest Laboratory. Based on the results of this testing and previously established criteria, a reductant-based flowsheet using glycolic acid and a nitric acid-based flowsheet were selected for the FY 1994 small-scale HTM testing.

  7. SASSE MODELING OF A URANIUM MOLYBDENUM SEPARATION FLOWSHEET

    SciTech Connect

    Laurinat, J

    2007-05-31

    H-Canyon Engineering (HCE) is evaluating the feasibility of processing material from the Super Kukla Prompt Burst Reactor, which operated at the Nevada Test Site from 1964 to 1978. This material is comprised of 90 wt % uranium (U) (at approximately 20% 235U enrichment) alloyed with 10 wt % molybdenum (Mo). The objective is to dissolve the material in nitric acid (HNO{sub 3}) in the H-Canyon dissolvers and then to process the dissolved material through H-Canyon First and Second Cycle solvent extraction. The U product from Second Cycle will be sent to the highly enriched uranium (HEU) blend down program. In the blend down program, enriched U from the 1EU product stream will be blended with natural U at a ratio of 1 part enriched U per 3.5 parts natural U to meet a reactor fuel specification of 4.95% 235U before being shipped for use by the Tennessee Valley Authority (TVA) in its nuclear plants. The TVA specification calls for <200 mg Mo/g U (200 ppm). Since natural U has about 10 mg Mo/g U, the required purity of the 1EU product prior to blending is about 800 mg Mo/g U, allowing for uncertainties. HCE requested that the Savannah River National Laboratory (SRNL) define a flowsheet for the safe and efficient processing of the U-10Mo material. This report presents a computational model of the solvent extraction portion of the proposed flowsheet. The two main objectives of the computational model are to demonstrate that the Mo impurity requirement can be met and to show that the solvent feed rates in the proposed flowsheet, in particular to 1A and 1D Banks, are adequate to prevent refluxing of U and thereby ensure nuclear criticality safety. SASSE (Spreadsheet Algorithm for Stagewise Solvent Extraction), a Microsoft Excel spreadsheet that supports Argonne National Laboratory's proprietary AMUSE (Argonne Model for Universal Solvent Extraction) code, was selected to model the U/Mo separation flowsheet. SASSE spreadsheet models of H-Canyon First and Second Cycle solvent

  8. Demonstration of an optimized TRUEX flowsheet for partitioning of actinides from actual ICPP sodium-bearing waste using centrifugal contactors in a shielded cell facility

    SciTech Connect

    Law, J.D.; Brewer, K.N.; Herbst, R.S.; Todd, T.A.; Olson, L.G.

    1998-01-01

    The TRUEX process is being evaluated at the Idaho Chemical Processing Plant (ICPP) for the separation of the actinides from acidic radioactive wastes stored at the ICPP. These efforts have culminated in recent demonstrations of the TRUEX process with actual tank waste. The first demonstration was performed in 1996 using 24 stages of 2-cm diameter centrifugal contactors and waste from tank WM-183. Based on the results of this flowsheet demonstration, the flowsheet was optimized and a second flowsheet demonstration was performed. This test also was performed using 2-cm diameter centrifugal contactors and waste from tank WM-183. However, the total number of contactor stages was reduced from 24 to 20. Also, the concentration of HEDPA in the strip solution was reduced from 0.04 M to 0.01 M in order to minimize the amount of phosphate in the HLW fraction, which would be immobilized into a glass waste form. This flowsheet demonstration was performed using centrifugal contactors installed in the shielded hot cell at the ICPP Remote Analytical Laboratory. The flowsheet tested consisted of six extraction stages, four scrub stages, six strip stages, two solvent was stages, and two acid rinse stages. An overall removal efficiency of 99.79% was obtained for the actinides. As a result, the activity of the actinides was reduced from 540 nCi/g in the feed to 0.90 nCi/g in the aqueous raffinate, which is well below the NRC Class A LLW requirement of 10 nCi/g for non-TRU waste. Removal efficiencies of 99.84%, 99.97%, 99.97%, 99.85%, and 99.76% were obtained for {sup 241}Am, {sup 238}Pu, {sup 239}Pu, {sup 235}U, and {sup 238}U, respectively.

  9. Organic chemical degradation by remote study of the redox conditions

    NASA Astrophysics Data System (ADS)

    Fernandez, P. M.; Revil, A.; Binley, A. M.; Bloem, E.; French, H. K.

    2014-12-01

    Monitoring the natural (and enhanced) degradation of organic contaminants is essential for managing groundwater quality in many parts of the world. Contaminated sites often have limited access, hence non-intrusive methods for studying redox processes, which drive the degradation of organic compounds, are required. One example is the degradation of de-icing chemicals (glycols and organic salts) released to the soil near airport runways during winter. This issue has been broadly studied at Oslo airport, Gardermoen, Norway using intrusive and non-intrusive methods. Here, we report on laboratory experiments that aim to study the potential of using a self-potential, DCresistivity, and time-domain induced polarization for geochemical characterization of the degradation of Propylene Glycol (PG). PG is completely miscible in water, does not adsorb to soil particles and does not contribute to the electrical conductivity of the soil water. When the contaminant is in the unsaturated zone near the water table, the oxygen is quickly consumed and the gas exchange with the surface is insufficient to ensure aerobic degradation, which is faster than anaerobic degradation. Since biodegradation of PG is highly oxygen demanding, anaerobic pockets can exist causing iron and manganese reduction. It is hypothesised that nitrate would boost the degradation rate under such conditions. In our experiment, we study PG degradation in a sand tank. We provide the system with an electron highway to bridge zones with different redox potential. This geo-battery system is characterized by self-potential, resistivity and induced polarization anomalies. An example of preliminary results with self-potential at two different times of the experiment can be seen in the illustration. These will be supplemented with more direct information on the redox chemistry: in-situ water sampling, pH, redox potential and electrical conductivity measurements. In parallel, a series of batch experiments have been

  10. CHEMICAL AND BIOLOGICAL TREATMENT OF THERMALLY CONDITIONED SLUDGE RECYCLE LIQUORS

    EPA Science Inventory

    The objective of this research project was to demonstrate and evaluate the feasibility of treating undiluted heat treatment liquor prior to its rerouting back to the head of the sewage treatment plant. Chemical and biological treatment processes were studied. Chemical treatment w...

  11. Preliminary evaluation of Am/Cm melter feed preparation process upset recovery flowsheets

    SciTech Connect

    Stone, M.E.

    2000-01-20

    This document summarizes the results from the development of flowsheets to recover from credible processing errors specified in TTR 99-MNSS/SE-006. The proposed flowsheets were developed in laboratory scale equipment and will be utilized with minor modifications for full scale demonstrations in the Am/Cm Pilot Facility.

  12. Chemical Enrichment and Physical Conditions in IZw18*

    NASA Technical Reports Server (NTRS)

    Lebouteiller, V.; Heap, S.; Hubeny, I.; Kunth, D.

    2013-01-01

    Low-metallicity star-forming dwarf galaxies are prime targets to understand the chemical enrichment of the interstellar medium. The H I region contains the bulk of the mass in blue compact dwarfs, and it provides important constraints on the dispersal and mixing of heavy elements released by successive star-formation episodes. The metallicity of the H I region is also a critical parameter to investigate the future star-formation history, as metals provide most of the gas cooling that will facilitate and sustain star formation. Aims. Our primary objective is to study the enrichment of the H I region and the interplay between star-formation history and metallicity evolution. Our secondary obje ctive is to constrain the spatial- and time-scales over which the HI and H II regions are enriched, and the mass range of stars responsible for the heavy element production. Finally, we aim to examine the gas heating and cooling mechanisms in the H I region. Methods. We observed the most metal-poor star-forming galaxy in the Local Universe, I Zw 18, with the Cosmic Origin Spectrograph onboard Hubble. The abundances in the neutral gas are derived from far-ultraviolet absorption-lines (H I, CIII, CIIi*, N I, OI,...) and are compared to the abundances in the H II region. Models are constructed to calculate the ionization structure and the thermal processes. We investigate the gas cooling in the HIi region through physical diagnostics drawn from the fine-structure level of C+. Results. We find that H I region abundances are lower by a factor of approx 2 as compared to the H II region. There is no differential depletion on dust between the H I and H II region. Using sulfur as a metallicity tracer, we calculate a metallicity of 1/46 Z(solar) (vs. 1/31 Z(solar) in the H II region). From the study of the C/O, [O/Fe], and N/O abundance ratios, we propose that C, N, O, and Fe are mainly produced in massive stars. We argue that the H I envelope may contain pockets of pristine gas with a

  13. Chemical enrichment and physical conditions in I Zw 18

    NASA Astrophysics Data System (ADS)

    Lebouteiller, V.; Heap, S.; Hubeny, I.; Kunth, D.

    2013-05-01

    Context. Low-metallicity star-forming dwarf galaxies are prime targets to understand the chemical enrichment of the interstellar medium. The H i region contains the bulk of the mass in blue compact dwarfs, and it provides important constraints on the dispersal and mixing of heavy elements released by successive star-formation episodes. The metallicity of the H i region is also a critical parameter to investigate the future star-formation history, as metals provide most of the gas cooling that will facilitate and sustain star formation. Aims: Our primary objective is to study the enrichment of the H i region and the interplay between star-formation history and metallicity evolution. Our secondary objective is to constrain the spatial- and time-scales over which the H i and H ii regions are enriched, and the mass range of stars responsible for the heavy element production. Finally, we aim to examine the gas heating and cooling mechanisms in the H i region. Methods: We observed the most metal-poor star-forming galaxy in the Local Universe, I Zw 18, with the Cosmic Origin Spectrograph onboard Hubble. The abundances in the neutral gas are derived from far-ultraviolet absorption-lines (H i, C ii, C ii*, N i, O i, ...) and are compared to the abundances in the H ii region. Models are constructed to calculate the ionization structure and the thermal processes. We investigate the gas cooling in the H i region through physical diagnostics drawn from the fine-structure level of C+. Results: We find that H i region abundances are lower by a factor of ~2 as compared to the H ii region. There is no differential depletion on dust between the H i and H ii region. Using sulfur as a metallicity tracer, we calculate a metallicity of 1/46 Z⊙ (vs. 1/31 Z⊙ in the H ii region). From the study of the C/O, [O/Fe], and N/O abundance ratios, we propose that C, N, O, and Fe are mainly produced in massive stars. We argue that the H i envelope may contain pockets of pristine gas with a

  14. EFFICIENT CHEMICAL TRANSFORMATIONS USING ALTERNATIVE REACTION CONDITIONS AND MEDIA

    EPA Science Inventory

    The diverse nature of chemical entities requires various green' strategic pathways in our quest towards attaining sustainability. A solvent-free approach that involves microwave (MW) exposure of neat reactants (undiluted) catalyzed by the surfaces of less-expensive and recyclable...

  15. Public Health Risk Conditioned by Chemical Composition of Ground Water

    NASA Astrophysics Data System (ADS)

    Yankovich, E.; Osipova, N.; Yankovich, K.; Matveenko, I.

    2016-03-01

    The article studies the public health potential risk originated from water consumption and estimated on the basis of the groundwater chemical composition. We have processed the results of chemical groundwater analysis in different aquifers of Tomsk district (Tomsk Oblast, Russia). More than 8400 samples of chemical groundwater analyses were taken during long-term observation period. Human health risk assessment of exposure to contaminants in drinking water was performed in accordance with the risk assessment guidance for public health concerning chemical pollution of the environment (Russian reference number: 2.1.10.1920-04-M, 2004). Identified potential risks were estimated for consuming water of each aquifer. The comparative analysis of water quality of different aquifers was performed on the basis of the risk coefficient of the total non-carcinogenic effects. The non-carcinogenic risk for the health of the Tomsk district population due to groundwater consumption without prior sanitary treatment was admitted acceptable. A rather similar picture is observed for all aquifers, although deeper aquifers show lower hazard coefficients.

  16. CHEMICAL SPECIATION OF INORGANIC COMPOUNDS UNDER HYDROTHERMAL CONDITIONS

    EPA Science Inventory

    This research will utilize the high-intensity x-rays available at the Advance Photon Source (APS) to study the inorganic chemistry occurring during the hydrothermal oxidation of tank waste and the chemistry associated with tank waste vitrification. Although the chemical conversio...

  17. Measurements of aerosol chemical composition in boreal forest summer conditions

    NASA Astrophysics Data System (ADS)

    ńijälä, M.; Junninen, H.; Ehn, M.; Petäjä, T.; Vogel, A.; Hoffmann, T.; Corrigan, A.; Russell, L.; Makkonen, U.; Virkkula, A.; Mäntykenttä, J.; Kulmala, M.; Worsnop, D.

    2012-04-01

    Boreal forests are an important biome, covering vast areas of the northern hemisphere and affecting the global climate change via various feedbacks [1]. Despite having relatively few anthropogenic primary aerosol sources, they always contain a non-negligible aerosol population [2]. This study describes aerosol chemical composition measurements using Aerodyne Aerosol Mass Spectrometer (C-ToF AMS, [3]), carried out at a boreal forest area in Hyytiälä, Southern Finland. The site, Helsinki University SMEAR II measurement station [4], is situated at a homogeneous Scots pine (Pinus sylvestris) forest stand. In addition to the station's permanent aerosol, gas phase and meteorological instruments, during the HUMPPA (Hyytiälä United Measurements of Photochemistry and Particles in Air) campaign in July 2010, a very comprehensive set of atmospheric chemistry measurement instrumentation was provided by the Max Planck Institute for chemistry, Johannes Gutenberg-University, University of California and the Finnish Meteorological institute. In this study aerosol chemical composition measurements from the campaign are presented. The dominant aerosol chemical species during the campaign were the organics, although periods with elevated amounts of particulate sulfates were also seen. The overall AMS measured particle mass concentrations varied from near zero to 27 μg/m observed during a forest fire smoke episode. The AMS measured aerosol mass loadings were found to agree well with DMPS derived mass concentrations (r2=0.998). The AMS data was also compared with three other aerosol instruments. The Marga instrument [5] was used to provide a quantitative semi-online measurement of inorganic chemical compounds in particle phase. Fourier Transform Infrared Spectroscopy (FTIR) analysis was performed on daily filter samples, enabling the identification and quantification of organic aerosol subspecies. Finally an Atmospheric Pressure Chemical Ionization Ion Trap Mass Spectrometer (APCI

  18. Resistance to chemical disinfection under conditions of microgravity

    NASA Astrophysics Data System (ADS)

    Marchin, George L.

    1998-01-01

    In unit gravity, bacteria and disinfecting resin beads co-sediment to the septum in a fluid processing apparatus (FPA) resulting in effective chemical disinfection. In microgravity bacteria in suspension have access to a larger volume of the FPA because of a lack of sedimentation. Further, when disinfecting resin beads are added to the FPA they also remain in suspension reducing their effective concentration. Typically, therefore, disinfection experiments in microgravity return larger numbers of viable bacteria than ground-based controls. Preliminary experiments aboard the MIR Space Station with Pseudomonas aeruginosa additionally suggest that the longer bacteria are retained in microgravity the more resistant they become to chemical disinfection. This phenomenon is probably due to additional time to develop resistant biofilms on the interior of the FPA. To partially solve these problems we have developed additional disinfecting materials to use in conjunction with polyiodide containing resin beads. One of these materials carbon beads coated with 3-trimethoxy silylpropyl dimethyloctadecyl ammonium chloride (Dow-Corning 5700®), acts synergistically with polyiodide resin disinfectants. Carbon beads so treated are still able to remove aqueous iodine from the water stream while providing an additional level of chemical disinfection. This additional capability prevents contamination of the carbon beads with heterotrophic bacteria and insures that bacteria surviving iodine disinfection are efficiently devitalized.

  19. Plutonium flowsheet development in miniature mixer-settlers

    SciTech Connect

    Hannaford, B.A.; Davis, G.D.

    1981-05-01

    Initial runs were completed in a new solvent extraction facility that has been built for testing coprocessing flowsheets with simulated LWR and FBR fuel solutions. The equipment, which is assembled in glove boxes, includes three 16-stage miniature mixer-settler banks with associated in-line monitors, pumping equipment, and sampling apparatus. Following shakedown runs with solutions containing uranium only, two flowsheet test runs were made with a simulated LWR fuel solution (U/Pu = 100). The solution was fed to an extraction-scrub bank, where 30% tributyl phosphate in normal paraffin hydrocarbon diluent was used to coextract uranium and plutonium. The extract was fed to a second mixer-settler bank, where all of the plutonium was stripped into an aqueous product stream using hydroxylamine nitrate for plutonium reduction; a controlled fraction of the uranium was simultaneously stripped to produce a U/Pu ratio of {similar_to}2. The amount of the uranium stripped with the plutonium was regulated by careful control of an organic backscrub stream. Finally, the residual uranium in the solvent was stripped in the third mixer-settler bank. The success of the experiments depended on precise control of very low liquid flow rates, and on in-line monitors which indicated the uranium or total heavy-metal concentrations. The most useful in-line device was the Mettler-Paar density meter, from which metal concentrations could be determined to within {similar_to}1 g/L. A miniature spectrophotometer also gave promising results for uranium analysis. Preliminary use of a Hewlett-Packard data acquisition system was satisfactory; recorded variables were temperature, solution density, liquid flow rates, and liquid levels.

  20. Hydrogen generation during IDMS demonstrations of the Late Washing and Nitric Acid flowsheets

    SciTech Connect

    Ritter, J.A.

    1992-10-19

    Recently, Late Washing (LW) and Nitric Acid (NA) flowsheets, developed respectively for the DWPF at Savannah River Technology Center SPC and CPC, were demonstrated in the one-fifth scale DWPF pilot facilities, PHEF and IDMS. Using the LW flowsheet, four runs in the PHEF produced enough PHA for two runs in the IDMS (denoted by PX4 and PX5). One of the objectives of these IDMS runs was to obtain peak hydrogen generation rates and compare them to the peak hydrogen generation rate design basis obtained from a previous IDMS run, based on the HAN and Formic Acid (HAN-FA) flowsheets.

  1. Evaluation of high-level waste vitrification feed preparation chemistry for an NCAW simulant, FY 1994: Alternate flowsheets (DRAFT)

    SciTech Connect

    Smith, H.D.; Merz, M.D.; Wiemers, K.D.; Smith, G.L.

    1996-02-01

    High-level radioactive waste stored in tanks at the U.S. Department of Energy`s (DOE`s) Hanford Site will be pretreated to concentrate radioactive constituents and fed to the vitrification plant A flowsheet for feed preparation within the vitrification plant (based on the Hanford Waste Vitrification Plant (HWVP) design) called for HCOOH addition during the feed preparation step to adjust rheology and glass redox conditions. However, the potential for generating H{sub 2} and NH{sub 3} during treatment of high-level waste (HLW) with HCOOH was identified at Pacific Northwest Laboratory (PNL). Studies at the University of Georgia, under contract with Savannah River Technology Center (SRTC) and PNL, have verified the catalytic role of noble metals (Pd, Rh, Ru), present in the waste, in the generation of H{sub 2} and NH{sub 3}. Both laboratory-scale and pilot-scale studies at SRTC have documented the H{sub 2} and NH{sub 3} generation phenomenal Because H{sub 2} and NH{sub 3} may create hazardous conditions in the vessel vapor space and offgas system of a vitrification plant, reducing the H{sub 2} generation rate and the NH{sub 3} generation to the lowest possible levels consistent with desired melter feed characteristics is important. The Fiscal Year 1993 and 1994 studies were conducted with simulated (non-radioactive), pre-treated neutralized current acid waste (NCAW). Neutralized current acid waste is a high-level waste originating from the plutonium/uranium extraction (PUREX) plant that has been partially denitrated with sugar, neutralized with NaOH, and is presently stored in double-shell tanks. The non-radioactive simulant used for the present study includes all of the trace components found in the waste, or substitutes a chemically similar element for radioactive or very toxic species. The composition and simulant preparation steps were chosen to best simulate the chemical processing characteristics of the actual waste.

  2. Achieving Chemical Equilibrium: The Role of Imposed Conditions in the Ammonia Formation Reaction

    ERIC Educational Resources Information Center

    Tellinghuisen, Joel

    2006-01-01

    Under conditions of constant temperature T and pressure P, chemical equilibrium occurs in a closed system (fixed mass) when the Gibbs free energy G of the reaction mixture is minimized. However, when chemical reactions occur under other conditions, other thermodynamic functions are minimized or maximized. For processes at constant T and volume V,…

  3. Flowsheet model for the electrochemical treatment of liquid radioactive wastes. Final report

    SciTech Connect

    Hobbs, D.T.; Prasad, S.; Farell, A.E.; Weidner, J.W.; White, R.E.

    1995-12-31

    The objective of this report is to describe the modeling and optimization procedure for the electrochemical removal of nitrates and nitrites from low level radioactive wastes. The simulation is carried out in SPEEDUP{trademark}, which is a state of the art flowsheet modeling package. The flowsheet model will provide a better understanding of the process and aid in the scale-up of the system. For example, the flowsheet model has shown that the electrochemical cell must be operated in batch mode to achieve 95 percent destruction. The flowsheet model is detailed in this report along with a systematic description of the batch optimization of the electrochemical cell. Results from two batch runs and one optimization run are also presented.

  4. Report on the flowsheet model for the electrochemical treatment of liquid radioactive wastes

    SciTech Connect

    Hobbs, D.T.

    1995-04-11

    The objective of this report is to describe the modeling and optimization procedure for the electrochemical removal of nitrates and nitrites from low level radioactive wastes. The simulation is carried out in SPEEDUP{trademark}, which is a state of the art flowsheet modeling package. The flowsheet model will provide a better understanding of the process and aid in the scale-up of the system. For example, the flowsheet model has shown that the electrochemical cell must be operated in batch mode to achieve 95% destruction. The present status of the flowsheet model is detailed in this report along with a systematic description of the batch optimization of the electrochemical cell. Results from two batch runs and one optimization run are also presented.

  5. Chemical water/rock interaction under reservoir condition

    SciTech Connect

    Watanabe, K.; Tanifuji, K.; Takahashi, H.; Wang, Y.; Yamasaki, N.; Nakatsuka, K.

    1995-01-26

    A simple model is proposed for water/rock interaction in rock fractures through which geothermal water flows. Water/rock interaction experiments were carried out at high temperature and pressure (200-350 C, 18 MPa) in order to obtain basic solubility and reaction rate data. Based on the experimental data, changes of idealized fracture apertures with time are calculated numerically. The results of the calculations show that the precipitation from water can lead to plugging of the fractures under certain conditions. Finally, the results are compared with the experimental data.

  6. An analysis of the New Technical Strategy Flowsheet applied to the watch list tanks

    SciTech Connect

    Booker, C.P.

    1994-09-01

    The New Technical Strategy Flowsheet is currently chosen for cleanup of the tanks on the Hanford Reservation. In this study, it is applied to a set of nine single shell tanks on the site. These tanks are considered to have a high potential for uncontrolled releases and have been placed on a watch list. Accordingly, it appears that any waste remediation strategy such as the New Technical Strategy Flowsheet might first be applied to these tanks.

  7. Optimizing cyanobacteria growth conditions in a sealed environment to enable chemical inhibition tests with volatile chemicals.

    PubMed

    Johnson, Tylor J; Zahler, Jacob D; Baldwin, Emily L; Zhou, Ruanbao; Gibbons, William R

    2016-07-01

    Cyanobacteria are currently being engineered to photosynthetically produce next-generation biofuels and high-value chemicals. Many of these chemicals are highly toxic to cyanobacteria, thus strains with increased tolerance need to be developed. The volatility of these chemicals may necessitate that experiments be conducted in a sealed environment to maintain chemical concentrations. Therefore, carbon sources such as NaHCO3 must be used for supporting cyanobacterial growth instead of CO2 sparging. The primary goal of this study was to determine the optimal initial concentration of NaHCO3 for use in growth trials, as well as if daily supplementation of NaHCO3 would allow for increased growth. The secondary goal was to determine the most accurate method to assess growth of Anabaena sp. PCC 7120 in a sealed environment with low biomass titers and small sample volumes. An initial concentration of 0.5g/L NaHCO3 was found to be optimal for cyanobacteria growth, and fed-batch additions of NaHCO3 marginally improved growth. A separate study determined that a sealed test tube environment is necessary to maintain stable titers of volatile chemicals in solution. This study also showed that a SYTO® 9 fluorescence-based assay for cell viability was superior for monitoring filamentous cyanobacterial growth compared to absorbance, chlorophyll α (chl a) content, and biomass content due to its accuracy, small sampling size (100μL), and high throughput capabilities. Therefore, in future chemical inhibition trials, it is recommended that 0.5g/L NaHCO3 is used as the carbon source, and that culture viability is monitored via the SYTO® 9 fluorescence-based assay that requires minimum sample size. PMID:27196637

  8. Source reduction from chemical plants using on-line optimization

    SciTech Connect

    Zhang, Z.; Pike, R.W.; Hertwig, T.A.

    1995-12-01

    An effective approach for source reduction in chemical plants has been demonstrated using on-line optimization with flowsheeting (ASPEN PLUS) for process optimization and parameter estimation and the Tjao-Biegler algorithm implemented in a mathematical programming language (GAMS/MINOS) for data reconciliation and gross error detection. Results for a Monsanto sulfuric acid plant with a Bailey distributed control system showed a 25% reduction in the sulfur dioxide emissions and a 17% improvement in the profit over the current operating conditions. Details of the methods used are described.

  9. SIMULATION OF ECOLOGICALLY CONSCIOUS CHEMICAL PROCESSES: FUGITIVE EMISSIONS VERSUS OPERATING CONDITIONS: JOURNAL ARTICLE

    EPA Science Inventory

    NRMRL-CIN-1531A Mata, T.M., Smith*, R.L., Young*, D., and Costa, C.A.V. "Simulation of Ecologically Conscious Chemical Processes: Fugitive Emissions versus Operating Conditions." Paper published in: CHEMPOR' 2001, 8th International Chemical Engineering Conference, Aveiro, Portu...

  10. Evaluation of chemical seed treatments for control of stripe rust in wheat under controlled conditions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The study was conducted under controlled conditions in a greenhouse in Pullman, WA. Seed of winter wheat ‘PS 279’ and spring wheat ‘Lemhi’ were treated by chemical companies with various chemicals. Seed of the two susceptible cultivars without treatment were used as non-treated controls. Five seeds ...

  11. Evaluation of conceptual flowsheets for incorporating Light Water Reactor (LWR) fuel materials in an advanced nuclear fuel cycle

    SciTech Connect

    Bell, J.T.; Burch, W.D.; Collins, E.D.; Forsberg, C.W.; Prince, B.E.; Bond, W.D.; Campbell, D.O.; Delene, J.G.; Mailen, J.C.

    1990-08-01

    A preliminary study by a group of experts at ORNL has generated and evaluated a number of aqueous and non-aqueous flowsheets for recovering transuranium actinides from LWR fuel for use as fuel in an LMR and, at the same time, for transmutation of the wastes to less hazardous materials. The need for proliferation resistance was a consideration in the flowsheets. The current state of development of the flowsheets was evaluated and recommendations for additional study were made. 3 refs., 6 figs.

  12. AFS-2 FLOWSHEET MODIFICATIONS TO ADDRESS THE INGROWTH OF PU(VI) DURING METAL DISSOLUTION

    SciTech Connect

    Crapse, K.; Rudisill, T.; O'Rourke, P.; Kyser, E.

    2014-07-02

    In support of the Alternate Feed Stock Two (AFS-2) PuO{sub 2} production campaign, Savannah River National Laboratory (SRNL) conducted a series of experiments concluding that dissolving Pu metal at 95°C using a 6–10 M HNO{sub 3} solution containing 0.05–0.2 M KF and 0–2 g/L B could reduce the oxidation of Pu(IV) to Pu(VI) as compared to dissolving Pu metal under the same conditions but at or near the boiling temperature. This flowsheet was demonstrated by conducting Pu metal dissolutions at 95°C to ensure that PuO{sub 2} solids were not formed during the dissolution. These dissolution parameters can be used for dissolving both Aqueous Polishing (AP) and MOX Process (MP) specification materials. Preceding the studies reported herein, two batches of Pu metal were dissolved in the H-Canyon 6.1D dissolver to prepare feed solution for the AFS-2 PuO{sub 2} production campaign. While in storage, UV-visible spectra obtained from an at-line spectrophotometer indicated the presence of Pu(VI). Analysis of the solutions also showed the presence of Fe, Ni, and Cr. Oxidation of Pu(IV) produced during metal dissolution to Pu(VI) is a concern for anion exchange purification. Anion exchange requires Pu in the +4 oxidation state for formation of the anionic plutonium(IV) hexanitrato complex which absorbs onto the resin. The presence of Pu(VI) in the anion feed solution would require a valence adjustment step to prevent losses. In addition, the presence of Cr(VI) would result in absorption of chromate ion onto the resin and could limit the purification of Pu from Cr which may challenge the purity specification of the final PuO{sub 2} product. Initial experiments were performed to quantify the rate of oxidation of Pu(IV) to Pu(VI) (presumed to be facilitated by Cr(VI)) as functions of the HNO{sub 3} concentration and temperature in simulated dissolution solutions containing Cr, Fe, and Ni. In these simulated Pu dissolutions studies, lowering the temperature from near boiling

  13. Flowsheet Evaluation for the Processing of U-MO Materials in H-Canyon

    SciTech Connect

    Pierce, R. A.

    2006-12-01

    H-Canyon Engineering (HCE) is evaluating the feasibility of processing material containing 90% uranium (20% 235U enrichment) alloyed with 10% molybdenum (Mo). The objective is to dissolve the material in nitric acid (HNO3) in the H-Canyon dissolvers to a U concentration of 17-22 g/L (3-4 g/L 235U) without the formation of precipitates. Following dissolution, the dissolved material will be processed through 1st and 2nd Cycle solvent extraction and the U sent to the U blend down program. The flowsheet must also consider any aqueous waste processing and solvent recycle issues. HCE requested that the Savannah River National Lab (SRNL) define a flowsheet for safely and efficiently processing the U-10Mo material. The flowsheet definition will occur in two phases. The first phase involves the evaluation of all available data related to the dissolution and solvent extraction of U-Mo materials to determine if a viable flowsheet can be developed, and to assess if there are additional data that must be obtained. Adequate data are available to conclude with confidence that a flowsheet is viable with sufficient operating margins. Data on the flowsheet development and processing of UMo fuels at Savannah River during the 1970’s and 1980’s provide the best information. Based on the data, the U-10Mo material can be dissolved in boiling 4.5-5.0 M HNO3 to a U concentration of 17-22 g/L and a corresponding Mo concentration of 1.7-2.2 g/L. Any nickel (Ni) cladding associated with the material will dissolve readily. After dissolution is complete, traditional solvent extraction flowsheets can be used to recover and purify the U. Evaporation of the resulting 1AW waste stream may be limited by Mo solubility. Although the flowsheet is fairly well-characterized, it should be noted that the material to be processed during this campaign is different than those previously processed in that it does not have aluminum cladding. As a result, some additional work is recommended to verify

  14. Chemical Conditioning as an Approach to Ischemic Stroke Tolerance: Mitochondria as the Target

    PubMed Central

    Jin, Zhen; Wu, Jinzi; Yan, Liang-Jun

    2016-01-01

    It is well established that the brain can be prepared to resist or tolerate ischemic stroke injury, and mitochondrion is a major target for this tolerance. The preparation of ischemic stroke tolerance can be achieved by three major approaches: ischemic conditioning, hypoxic conditioning and chemical conditioning. In each conditioning approach, there are often two strategies that can be used to achieve the conditioning effects, namely preconditioning (Pre-C) and postconditioning (Post-C). In this review, we focus on chemical conditioning of mitochondrial proteins as targets for neuroprotection against ischemic stroke injury. Mitochondrial targets covered include complexes I, II, IV, the ATP-sensitive potassium channel (mitoKATP), adenine dinucleotide translocase (ANT) and the mitochondrial permeability transition pore (mPTP). While numerous mitochondrial proteins have not been evaluated in the context of chemical conditioning and ischemic stroke tolerance, the paradigms and approaches reviewed in this article should provide general guidelines on testing those mitochondrial components that have not been investigated. A deep understanding of mitochondria as the target of chemical conditioning for ischemic stroke tolerance should provide valuable insights into strategies for fighting ischemic stroke, a leading cause of death in the world. PMID:27005615

  15. An artificial intelligence method for the synthesis of heat-integrated distillation flowsheets

    SciTech Connect

    Fang-Yu Han; Ben-Guang Rong

    1996-12-31

    In this paper, a concept of Heat-Integrated Distillation Flowsheet (HIDF) is proposed. It refers to the multicomponent separation flowsheet which is composed of simple and complex columns and in which heat integration is considered so as to achieve minimum energy consumption. The HIDF is very different from the Heat-Integrated Distillation Sequences (HIDS) in the literature which only consists of simple columns. In this paper, an artificial intelligence method is proposed for the synthesis of HIDF. It is based on the Database, Simulator, Heat Exchanger Network, and four Knowledge Bases which are all developed by the authors and their coworkers. A strategy of eight steps which combines the knowledge-based and rigorous algorithms is adopted for the synthesis of HIDF. The illustrated examples for the conventional distillation and extractive distillation show that the practical minimum energy consumption distillation flowsheets; can be generated with this method.

  16. FLOWSHEET FOR ALUMINUM REMOVAL FROM SLUDGE BATCH 6

    SciTech Connect

    Pike, J; Jeffrey Gillam, J

    2008-12-17

    Samples of Tank 12 sludge slurry show a substantially larger fraction of aluminum than originally identified in sludge batch planning. The Liquid Waste Organization (LWO) plans to formulate Sludge Batch 6 (SB6) with about one half of the sludge slurry in Tank 12 and one half of the sludge slurry in Tank 4. LWO identified aluminum dissolution as a method to mitigate the effect of having about 50% more solids in High Level Waste (HLW) sludge than previously planned. Previous aluminum dissolution performed in a HLW tank in 1982 was performed at approximately 85 C for 5 days and dissolved nearly 80% of the aluminum in the sludge slurry. In 2008, LWO successfully dissolved 64% of the aluminum at approximately 60 C in 46 days with minimal tank modifications and using only slurry pumps as a heat source. This report establishes the technical basis and flowsheet for performing an aluminum removal process in Tank 51 for SB6 that incorporates the lessons learned from previous aluminum dissolution evolutions. For SB6, aluminum dissolution process temperature will be held at a minimum of 65 C for at least 24 days, but as long as practical or until as much as 80% of the aluminum is dissolved. As planned, an aluminum removal process can reduce the aluminum in SB6 from about 84,500 kg to as little as 17,900 kg with a corresponding reduction of total insoluble solids in the batch from 246,000 kg to 131,000 kg. The extent of the reduction may be limited by the time available to maintain Tank 51 at dissolution temperature. The range of dissolution in four weeks based on the known variability in dissolution kinetics can range from 44 to more than 80%. At 44% of the aluminum dissolved, the mass reduction is approximately 1/2 of the mass noted above, i.e., 33,300 kg of aluminum instead of 66,600 kg. Planning to reach 80% of the aluminum dissolved should allow a maximum of 81 days for dissolution and reduce the allowance if test data shows faster kinetics. 47,800 kg of the dissolved

  17. Effects of physical conditioning on heat tolerance in chemical-defense gear. Master's thesis

    SciTech Connect

    Nauss, M.M.

    1986-06-01

    Today the threat of chemical warfare is real. The only effective defense is the use of chemical defense gear and gas masks. Since they render chemical-warfare gases and liquids impermeable to penetration, they also prohibit sweat evaporation in conditions of thermal stress and thus, contribute to heat illness development. Historically, it has been the hot, humid tropics where United Nation's peacekeeping forces have been called, thus the use of chemical-defense gear in these regions is a realistic possibility and heat illness could affect the outcome of any mission carried out there. The human body only operates within a narrow range of core temparatures, and heat illness is the result of a breakdown in homeostasis. Many factors influence heat tolerance, thus maintaining core temperature within a safe range. Adequate hydration, acclimitization to heat, low body weight, young age, low alcohol intake, and physical fitness all contribute to heat tolerance. This proposal attempts to look specifically at the effect of physical conditioning on heat tolerance in chemical-defense gear as a possible solution to the heat-stress problem noted in this gear. Trainee graduates attending technical training schools at Lackland AFB, Texas, will be tested for maximum oxygen uptake (VO/2max) and heat tolerance time (HTT) in chemical defense gear on bicycle ergometers at Brooks AFB, Texas. Half of these subjects will be physically conditioned for 12 weeks.

  18. Efficient Nonlinear Programming Algorithms for Chemical Process Control and Operations

    NASA Astrophysics Data System (ADS)

    Biegler, Lorenz T.

    Optimization is applied in numerous areas of chemical engineering including the development of process models from experimental data, design of process flowsheets and equipment, planning and scheduling of chemical process operations, and the analysis of chemical processes under uncertainty and adverse conditions. These off-line tasks require the solution of nonlinear programs (NLPs) with detailed, large-scale process models. Recently, these tasks have been complemented by time-critical, on-line optimization problems with differential-algebraic equation (DAE) process models that describe process behavior over a wide range of operating conditions, and must be solved sufficiently quickly. This paper describes recent advances in this area especially with dynamic models. We outline large-scale NLP formulations and algorithms as well as NLP sensitivity for on-line applications, and illustrate these advances on a commercial-scale low density polyethylene (LDPE) process.

  19. Study of multistage oxidation by flowsheet calculations on a combined heat and power molten carbonate fuel cell plant

    NASA Astrophysics Data System (ADS)

    Au, S. F.; Woudstra, N.; Hemmes, K.

    The multistage oxidation configuration consists of a set of serially connected fuel cell stacks. By connecting the stacks serially, more homogenous current distribution over the cell surface can be achieved resulting in lower irreversible losses. This article presents a detailed assessment of multistage oxidation by flowsheet calculations in which the influence of operating temperature and gas composition on the fuel cell performance is incorporated. A 250 kW molten carbonate fuel cell (MCFC) combined heat and power (CHP) plant is used as reference and the fuel cell stack unit is substituted by two serially connected units ( N=2). Two multistage configurations are examined: (A) both anode and cathode flows are serially connected; (B) only the anode flow is serially connected while the cathode flow is parallel connected. For all systems, the total cell active area, cell current density, overall fuel utilization and gas temperature at the inlet and outlet of the fuel cell array are kept constant. Fuel cell performance at the operating conditions is calculated using a numerical model of the flowsheeting program. Influences of operating temperature and gas composition on the cell performance are incorporated using empirical relations that describe irreversible losses of the cell as function of these parameters. System performances are compared in order to assess the benefits of the multistage oxidation configurations. Differences in performance between the two multistage oxidation configurations are studied by analyzing the difference in exergy loss of stacks, stack power output, cooling requirement and cathode gas massflow and composition. Detailed flowsheet calculations show that the improvement in efficiency is about 0.6% for configuration A, and 0.8% for configuration B. Improvements are obtained by the enhanced fuel cell power output while the expander power output is slightly reduced. Heat output is slightly reduced due to the improved fuel cell conversion

  20. Report for Treating Hanford LAW and WTP SW Simulants: Pilot Plant Mineralizing Flowsheet

    SciTech Connect

    Arlin Olson

    2012-02-28

    The US Department of Energy is responsible for managing the disposal of radioactive liquid waste in underground storage tanks at the Hanford site in Washington State. The Hanford waste treatment and immobilization plant (WPT) will separate the waste into a small volume of high level waste (HLW), containing most of the radioactive constituents, and a larger volume of low activity waste (LAW), containing most of the non-radioactive chemical and hazardous constituents. The HLW and LAW will be converted into immobilized waste forms for disposal. Currently there is inadequate LAW vitrification capacity planned at the WTP to complete the mission within the required timeframe. Therefore additional LAW capacity is required. One candidate supplemental treatment technology is the fluidized bed steam reformer process (FBSR). This report describes the demonstration testing of the FBSR process using a mineralizing flowsheet for treating simulated Hanford LAW and secondary waste from the WTP (WTP SW). The FBSR testing project produced leach-resistant solid products and environmentally compliant gaseous effluents. The solid products incorporated normally soluble ions into an alkali alumino-silicate (NaS) mineral matrix. Gaseous emissions were found to be within regulatory limits. Cesium and rhenium were captured in the mineralized products with system removal efficiencies of 99.999% and 99.998 respectively. The durability and leach performance of the FBSR granular solid were superior to the low activity reference material (LMR) glass standards. Normalized product consistency test (PCT) release rates for constituents of concern were approximately 2 orders of magnitude less than that of sodium in the Hanford glass [standard].

  1. Chemical Kinetic Study of Toluene Oxidation Under Premixed and Nonpremixed Conditions

    SciTech Connect

    Costa, I D; Bozzelli, J W; Seiser, R; Pitz, W J; Westbrook, C K; Chen, C -; Fournet, R; Seshadri, K; Battin-Leclerc, F; Billaud, F

    2003-12-10

    A study was performed to elucidate the chemical-kinetic mechanism of combustion of toluene. A detailed chemical-kinetic mechanism for toluene was improved by adding a more accurate description of the phenyl + O{sub 2} reaction channels, toluene decomposition reactions and the benzyl + O reaction. Results of the chemical kinetic mechanism are compared with experimental data obtained from premixed and non-premixed systems. Under premixed conditions, predicted ignition delay times are compared with new experimental data obtained in shock tube. Also, calculated species concentration histories are compared to experimental flow reactor data from the literature. Under non-premixed conditions, critical conditions of extinction and autoignition were measured in strained laminar flows in the counterflow configuration. Numerical calculations are performed using the chemical-kinetic mechanism at conditions corresponding to those in the experiments. Critical conditions of extinction and autoignition are predicted and compared with the experimental data. Comparisons between the model predictions and experimental results of ignition delay times in shock tube, and extinction and autoignition in non-premixed systems show that the chemical-kinetic mechanism predicts that toluene/air is overall less reactive than observed in the experiments. For both premixed and non-premixed systems, sensitivity analysis was used to identify the reaction rate constants that control the overall rate of oxidation in each of the systems considered. Under shock tube conditions, the reactions that influence ignition delay time are H + O{sub 2} chain branching, the toluene decomposition reaction to give an H atom, and the toluene + H abstraction reaction. The reactions that influence autoignition in non-premixed systems involve the benzyl + HO{sub 2} reaction and the phenyl + O{sub 2} reaction.

  2. ACCURACY OF PESTICIDE REFERENCE STANDARD SOLUTIONS. PART II. CHEMICAL STABILITY UNDER FOUR STORAGE CONDITIONS

    EPA Science Inventory

    A study was undertaken to assess the long-term chemical stability of dilute standard pesticide solutions of 4 compound classes. The solutions were studied under 4 storage conditions: freezer at -15C; refrigerator at 3C; ambient temperature in the dark; and ambient temperature on ...

  3. Effects of biomass types and carbonization conditions on the chemical characteristics of hydrochar

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Effects of biomass types (sugar beet pulp vs. bark mulch) and hydrothermal carbonization (HTC) processing conditions (temperature, residence time, and the phase of reaction medium) on the chemical characteristics of hydrochars were examined by elemental analysis, advanced solid-state nuclear magneti...

  4. Prioritized List of Research Needs to support MRWFD Case Study Flowsheet Advancement

    SciTech Connect

    Law, Jack Douglas; Soelberg, Nicholas Ray

    2015-06-17

    In FY-13, a case study evaluation was performed of full recycle technologies for both the processing of light-water reactor (LWR) used nuclear fuels as well as fast reactor (FR) fuel in the full recycle option. This effort focused on the identification of the case study processes and the initial preparation of material balance flowsheets for the identified technologies. In identifying the case study flowsheets, it was decided that two cases would be developed: one which identifies the flowsheet as currently developed and another near-term target flowsheet which identifies the flowsheet as envisioned within two years, pending the results of ongoing research. The case study focus is on homogeneous aqueous recycle of the U/TRU resulting from the processing of LWR fuel as feed for metal fuel fabrication. The metal fuel is utilized in a sodium-cooled fast reactor, and the used fast reactor fuel is processed using electrochemical separations. The recovered U/TRU from electrochemical separations is recycled to fuel fabrication and the fast reactor. Waste streams from the aqueous and electrochemical processing are treated and prepared for disposition. Off-gas from the separations and waste processing are also treated. As part of the FY-13 effort, preliminary process unknowns and research needs to advance the near-term target flowsheets were identified. In FY-14, these research needs were updated, expanded and prioritized. This report again updates the prioritized list of research needs based upon results to date in FY-15. The research needs are listed for each of the main portions of the flowsheet: 1) Aqueous headend, 2) Headend tritium pretreatment off-gas, 3) Aqueous U/Pu/Np recovery, 4) Aqueous TRU product solidification, 5) Aqueous actinide/lanthanide separation, 6) Aqueous off-gas treatment, 7) Aqueous HLW management, 8) Treatment of aqueous process wastes, 9) E-chem actinide separations, 10) E-chem off-gas, 11) E-chem HLW management. The identified research needs

  5. Biodegradation of chemicals in a standardized test and in environmental conditions.

    PubMed

    Ahtiainen, Jukka; Aalto, Miia; Pessala, Piia

    2003-05-01

    The estimation of biodegradation rates is an important source of uncertainty in chemical risk assessment. The existing OECD tests for ready biodegradability have been developed to devise screening methods to determine whether a chemical is potentially easily biodegradable, rather than to predict the actual rate, of biodegradation in the environment. However, risk assessment needs degradation rates. In practice these rates are often estimated (default values) from ready biodegradability tests. These tests have many compromising arbitrary features compared to the situation in the real environment. One important difference is the concentration of the chemical. In wastewater treatment or in the environment many chemicals are present at ng l(-1) to microg l(-1) levels whereas in the tests the concentrations exceed 10-400 mg carbon per litre. These different concentrations of the chemical will lead to different growth kinetics and hence different biodegradation rates. At high concentrations the chemical, if it is degradable, can serve as a primary substrate and competent microorganisms will grow exponentially, resulting in a sigmoid biodegradation curve. At low environmental concentrations the chemical does not serve as a primary substrate, and therefore does not support significant growth of the degraders, and the substrate has a linear biodegradation rate. In this study the biodegradation rates of two reference chemicals, aniline and 4-chloroaniline, were compared in a standard method and in more realistic conditions at low concentrations, using 14C-labelled substances and different sources of inocula. Biomass evolution during the tests was monitored by adenosine triphosphate measurement and also on the basis of the residual 14C-activity in the particulate matter. The results partly support the thesis that low concentrations lead to different biodegradation kinetics compared to the concentrations used in the standard tests. Furthermore the biodegradation rates of the

  6. Modeling the kinetics of microbial degradation of deicing chemicals in porous media under flow conditions.

    PubMed

    Wehrer, Markus; Jaesche, Philipp; Totsche, Kai Uwe

    2012-09-01

    A quantitative knowledge of the fate of deicing chemicals in the subsurface can be provided by joint analysis of lab experiments with numerical simulation models. In the present study, published experimental data of microbial degradation of the deicing chemical propylene glycol (PG) under flow conditions in soil columns were simulated inversely to receive the parameters of degradation. We evaluated different scenarios of an advection-dispersion model including different terms for degradation, such as zero order, first order and inclusion of a growing and decaying biomass for their ability to explain the data. The general break-through behavior of propylene glycol in soil columns can be simulated well using a coupled model of solute transport and degradation with growth and decay of biomass. The susceptibility of the model to non-unique solutions was investigated using systematical forward and inverse simulations. We found that the model tends to equifinal solutions under certain conditions. PMID:22609860

  7. Synthesis of graphene by chemical vapor deposition: effect of growth conditions.

    PubMed

    Su, Dan; Ren, Mingwei; Li, Xing'ao; Huang, Wei

    2013-10-01

    Graphene has attracted a great deal of attention due to its extraordinary physical and chemical properties. But the control of growth of high-quality, large-area and inexpensive graphene is still the bottleneck for practical applications. Chemical vapor deposition (CVD) has become the most common method for graphene growth due to its high production and large area of product. However, it generally suffers from an uncontrollable carbon precipitation effect that leads to inhomogeneous growth and strongly dependent on to the growth conditions. Until now, scientists have struggled to synthesize higher quality, larger area graphene through changing the experimental conditions. In this review, the progress made in the last few years concerning the exploration of preparation graphene by CVD is summarized in three aspects (catalysts, precursors and experimental parameters) that influence graphene growth. PMID:24245104

  8. Chemically transferable coarse-grained potentials from conditional reversible work calculations.

    PubMed

    Brini, E; van der Vegt, N F A

    2012-10-21

    The representability and transferability of effective pair potentials used in multiscale simulations of soft matter systems is ill understood. In this paper, we study liquid state systems composed of n-alkanes, the coarse-grained (CG) potential of which may be assumed pairwise additive and has been obtained using the conditional reversible work (CRW) method. The CRW method is a free-energy-based coarse-graining procedure, which, by means of performing the coarse graining at pair level, rigorously provides a pair potential that describes the interaction free energy between two mapped atom groups (beads) embedded in their respective chemical environments. The pairwise nature of the interactions combined with their dependence on the chemically bonded environment makes CRW potentials ideally suited in studies of chemical transferability. We report CRW potentials for hexane using a mapping scheme that merges two heavy atoms in one CG bead. It is shown that the model is chemically and thermodynamically transferable to alkanes of different chain lengths in the liquid phase at temperatures between the melting and the boiling point under atmospheric (1 atm) pressure conditions. It is further shown that CRW-CG potentials may be readily obtained from a single simulation of the liquid state using the free energy perturbation method, thereby providing a fast and versatile molecular coarse graining method for aliphatic molecules. PMID:23083154

  9. Relative toxicity of pyrolysis gases from materials - Effects of chemical composition and test conditions

    NASA Technical Reports Server (NTRS)

    Hilado, C. J.; Cumming, H. J.

    1978-01-01

    Relative toxicity test data on 270 materials are presented, based on test procedures developed at the University of San Francisco. The effects of chemical composition, using data on 13 types of synthetic polymers and eight types of fabrics, are discussed. Selected materials were evaluated using nine test conditions with the USF method, and using methods developed at the FAA Civil Aeromedical Institute, Douglas Aircraft Company and San Jose State University.

  10. Effect of cooling condition on chemical vapor deposition synthesis of graphene on copper catalyst.

    PubMed

    Choi, Dong Soo; Kim, Keun Soo; Kim, Hyeongkeun; Kim, Yena; Kim, TaeYoung; Rhy, Se-hyun; Yang, Cheol-Min; Yoon, Dae Ho; Yang, Woo Seok

    2014-11-26

    Here, we show that chemical vapor deposition growth of graphene on copper foil is strongly affected by the cooling conditions. Variation of cooling conditions such as cooling rate and hydrocarbon concentration in the cooling step has yielded graphene islands with different sizes, density of nuclei, and growth rates. The nucleation site density on Cu substrate is greatly reduced when the fast cooling condition was applied, while continuing methane flow during the cooling step also influences the nucleation and growth rate. Raman spectra indicate that the graphene synthesized under fast cooling condition and methane flow on cool-down exhibit superior quality of graphene. Further studies suggest that careful control of the cooling rate and CH4 gas flow on the cooling step yield a high quality of graphene. PMID:25386721

  11. Analysis of initial reactions of MALDI based on chemical properties of matrixes and excitation condition.

    PubMed

    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. PMID:22799495

  12. Decomposition Dynamics and Changes in Chemical Composition of Wheat Straw Residue under Anaerobic and Aerobic Conditions.

    PubMed

    Gao, Hongjian; Chen, Xi; Wei, Junling; Zhang, Yajie; Zhang, Ligan; Chang, Jiang; Thompson, Michael L

    2016-01-01

    Soil aeration is a crucial factor that regulates crop residue decomposition, and the chemical composition of decomposing crop residues may change the forms and availability of soil nutrients, such as N and P. However, to date, differences in the chemical composition of crop straw residues after incorporation into soil and during its decomposition under anaerobic vs. aerobic conditions have not been well documented. The objective of the present study was to assess changes in the C-containing functional groups of wheat straw residue during its decomposition in anaerobic and aerobic environments. A 12-month incubation experiment was carried out to investigate the temporal variations of mass, carbon, and nitrogen loss, as well as changes in the chemical composition of wheat (Triticum aestivum L) straw residues under anaerobic and aerobic conditions by measuring C-containing functional groups using solid state nuclear magnetic resonance (NMR) spectroscopy. The residual mass, carbon content, and nitrogen content of the straw residue sharply declined during the initial 3 months, and then slowly decreased during the last incubation period from 3 to 12 months. The decomposition rate constant (k) for mass loss under aerobic conditions (0.022 d-1) was higher than that under anaerobic conditions (0.014 d-1). The residual mass percentage of cellulose and hemicellulose in the wheat straw gradually declined, whereas that of lignin gradually increased during the entire 12-month incubation period. The NMR spectra of C-containing functional groups in the decomposing straw under both aerobic and anaerobic conditions were similar at the beginning of the incubation as well as at 1 month, 6 months, and 12 months. The main alterations in C-containing functional groups during the decomposition of wheat straw were a decrease in the relative abundances of O-alkyl C and an increase in the relative abundances of alkyl C, aromatic C and COO/N-C = O functional groups. The NMR signals of alkyl C

  13. Decomposition Dynamics and Changes in Chemical Composition of Wheat Straw Residue under Anaerobic and Aerobic Conditions

    PubMed Central

    Gao, Hongjian; Chen, Xi; Wei, Junling; Zhang, Yajie; Zhang, Ligan; Chang, Jiang; Thompson, Michael L.

    2016-01-01

    Soil aeration is a crucial factor that regulates crop residue decomposition, and the chemical composition of decomposing crop residues may change the forms and availability of soil nutrients, such as N and P. However, to date, differences in the chemical composition of crop straw residues after incorporation into soil and during its decomposition under anaerobic vs. aerobic conditions have not been well documented. The objective of the present study was to assess changes in the C-containing functional groups of wheat straw residue during its decomposition in anaerobic and aerobic environments. A 12-month incubation experiment was carried out to investigate the temporal variations of mass, carbon, and nitrogen loss, as well as changes in the chemical composition of wheat (Triticum aestivum L) straw residues under anaerobic and aerobic conditions by measuring C-containing functional groups using solid state nuclear magnetic resonance (NMR) spectroscopy. The residual mass, carbon content, and nitrogen content of the straw residue sharply declined during the initial 3 months, and then slowly decreased during the last incubation period from 3 to 12 months. The decomposition rate constant (k) for mass loss under aerobic conditions (0.022 d-1) was higher than that under anaerobic conditions (0.014 d-1). The residual mass percentage of cellulose and hemicellulose in the wheat straw gradually declined, whereas that of lignin gradually increased during the entire 12-month incubation period. The NMR spectra of C-containing functional groups in the decomposing straw under both aerobic and anaerobic conditions were similar at the beginning of the incubation as well as at 1 month, 6 months, and 12 months. The main alterations in C-containing functional groups during the decomposition of wheat straw were a decrease in the relative abundances of O-alkyl C and an increase in the relative abundances of alkyl C, aromatic C and COO/N-C = O functional groups. The NMR signals of alkyl C

  14. Evaluation of the applicability of nonlinear programming algorithms to a typical commercial process flow-sheeting simulator (Volumes I and II)

    SciTech Connect

    Richard, M.J.

    1987-01-01

    An efficient methodology for using commercial flowsheeting programs with advanced mathematical programming algorithms was developed for the optimization of operating plants. The methodology was demonstrated and validated using ChemShare Corporation's DESIGN/2000 simulation of the Freeport Chemical Company's plant for sulfuric acid manufacture and three nonlinear programming techniques: successive linear programming, successive quadratic programming, and the generalized reduced-gradient method. The application of this methodology begins with the development of a feasible base-case simulation. Partial derivatives of the economic model and constraint equations are computed using fully converged simulations. This information is used to formulate an optimization problem that can be solved with the NLP algorithms giving improved values of the economic model. A line search is constructed through the point found from the nonlinear programming algorithm to find the best feasible point to repeat the procedure. The procedure is repeated using the ChemShare simulation program and the NLP code until convergence criteria are met. This method was applied to three flowsheeting problems; a plant-scale-contact sulfuric acid process model, a packed-bed-reactor design model, and an adiabatic-flash problem.

  15. Influences of solution chemical conditions on mobilization of TNT from contaminated soil

    SciTech Connect

    Dante, D.A.; Tiller, C.L.; Pennell, K.D.

    1996-12-31

    2,4,6-trinitrotoluene (TNT) and its byproducts are common contaminants on US military installations. Many potential remediation processes are in part limited by the transfer of TNT from the contaminated soil into the aqueous phase. The purpose of this research is to assess the release of TNT from contaminated soil under varying solution chemical conditions. In particular, influences of pH, aquatic natural organic matter, and addition of two surfactants is investigated. Uncontaminated soil was collected from a near-surface site at the Alabama Army Ammunition Plant and was artificially contaminated with TNT prior to the mobilization experiments. Results for the pH experiments show that more TNT is mobilized at neutral pH conditions than at low pH conditions. The presence of dissolved organic matter enhances the release of TNT from soil, but not by a large amount. Surfactant addition has the most significant effect on TNT mobilization.

  16. Pilot-Scale TRUEX Flowsheet Testing for Separation of Actinides and Lanthanides from Used Nuclear Fuel

    SciTech Connect

    Jack D. Law; Troy G. Garn; David H. Meikrantz; Jamie Warburton

    2010-01-01

    Advanced aqueous separation processes are being developed for the recycling of used nuclear fuel as part of the U.S. Department of Energy Nuclear Energy Advanced Fuel Cycle Initiative. The Transuranic Extraction (TRUEX) Process is being developed as part of these advanced separations processes for the separation of actinides and lanthanides from the used nuclear fuel. Testing of a TRUEX flowsheet has been performed using a thirty stage, 5-cm centrifugal contactor pilot plant. This testing was performed using a non-radioactive feed surrogate and data were collected and analyzed to evaluate removal efficiencies of the lanthanides, mass transfer efficiency of the lanthanides in the extraction and strip sections of the flowsheet, and the temperature profile of the process solutions throughout the centrifugal contactor pilot plant. Results indicate >99.9% separation for all lanthanides and mass transfer efficiencies typically ranging from 85% to 100%. Solution temperatures for each contactor stage, as well as general process performance, are also described.

  17. Double torsion fracture mechanics testing of shales under chemically reactive conditions

    NASA Astrophysics Data System (ADS)

    Chen, X.; Callahan, O. A.; Holder, J. T.; Olson, J. E.; Eichhubl, P.

    2015-12-01

    Fracture properties of shales is vital for applications such as shale and tight gas development, and seal performance of carbon storage reservoirs. We analyze the fracture behavior from samples of Marcellus, Woodford, and Mancos shales using double-torsion (DT) load relaxation fracture tests. The DT test allows the determination of mode-I fracture toughness (KIC), subcritical crack growth index (SCI), and the stress-intensity factor vs crack velocity (K-V) curves. Samples are tested at ambient air and aqueous conditions with variable ionic concentrations of NaCl and CaCl2, and temperatures up to 70 to determine the effects of chemical/environmental conditions on fracture. Under ambient air condition, KIC determined from DT tests is 1.51±0.32, 0.85±0.25, 1.08±0.17 MPam1/2 for Marcellus, Woodford, and Mancos shales, respectively. Tests under water showed considerable change of KIC compared to ambient condition, with 10.6% increase for Marcellus, 36.5% decrease for Woodford, and 6.7% decrease for Mancos shales. SCI under ambient air condition is between 56 and 80 for the shales tested. The presence of water results in a significant reduction of the SCI from 70% to 85% compared to air condition. Tests under chemically reactive solutions are currently being performed with temperature control. K-V curves under ambient air conditions are linear with stable SCI throughout the load-relaxation period. However, tests conducted under water result in an initial cracking period with SCI values comparable to ambient air tests, which then gradually transition into stable but significantly lower SCI values of 10-20. The non-linear K-V curves reveal that crack propagation in shales is initially limited by the transport of chemical agents due to their low permeability. Only after the initial cracking do interactions at the crack tip lead to cracking controlled by faster stress corrosion reactions. The decrease of SCI in water indicates higher crack propagation velocity due to

  18. Chemical immobilization of crested porcupines with tiletamine HCl and zolazepam HCl (Zoletil) under field conditions.

    PubMed

    Massolo, Alessandro; Sforzi, Andrea; Lovari, Sandro

    2003-07-01

    The combination of tiletamine HCl and zolazepam HCl has been used on many species of wild mammals. Short induction time, low dosage, satisfactory safety margins, relatively constant immobilization time, and smooth recovery are benefits reported. This combination (Zoletil 100) was used during a study on behavioural ecology of the crested porcupine (Hystrix cristata) in a Mediterranean coastal area (Maremma Regional Park, Tuscany, Italy). We used this mixture 42 times on 31 individuals. Mean adult dose was (+/- SE) 7.24 +/- 0.37 mg/kg (74.0 +/- 3.0 mg/individual). Average adult induction time was 5.3 min (+/- 1.1) and average adult immobilization time was 22.6 min (+/- 6.0). One adult male porcupine died after chemical restraints. The use of tiletamine-zolazepam seems adequate for chemical immobilization of crested porcupines under field conditions, mainly because of its short induction time, small volume to be injected and wide safety margin. PMID:14567239

  19. Chemical kinetic modeling of chlorinated hydrocarbons under stirred-reactor conditions

    SciTech Connect

    Pitz, W.J.; Westbrook, C.K.

    1990-10-04

    The combustin of chloroethane is modeled as a stirred reactor so that we can study critical emission characteristics of the reactor as a function of residence time. We examine important operating conditions such as pressure, temperature, and equivalence ratio and their influence on destructive efficiency of chloroethane and production of other chlorinated products. The model uses a detailed chemical kinetic mechanism that we have developed previously for C{sub 3} hydrocarbons. We have added to this mechanism the chemical kinetic mechanism for C{sub 2} chlorinated hydrocarbons developed by Senkan and coworkers. Some reactions have been added to Senkan's mechanism and some of the reaction-rate expressions have been updated to reflect recent developments in the literature. In the modeling calculations, sensitivity coefficients are determined to find which reaction-rate constants have the largest effect on destructive efficiency. 25 refs., 6 figs., 1 tab.

  20. High-sensitivity chemical derivatization NMR analysis for condition monitoring of aged elastomers.

    SciTech Connect

    Assink, Roger Alan; Celina, Mathias Christopher; Skutnik, Julie Michelle

    2004-06-01

    An aged polybutadiene-based elastomer was reacted with trifluoroacetic anhydride (TFAA) and subsequently analyzed via 19F NMR spectroscopy. Derivatization between the TFAA and hydroxyl functionalities produced during thermo-oxidative aging was achieved, resulting in the formation of trifluoroester groups on the polymer. Primary and secondary alcohols were confirmed to be the main oxidation products of this material, and the total percent oxidation correlated with data obtained from oxidation rate measurements. The chemical derivatization appears to be highly sensitive and can be used to establish the presence and identity of oxidation products in aged polymeric materials. This methodology represents a novel condition monitoring approach for the detection of chemical changes that are otherwise difficult to analyze.

  1. Development and Testing of an Americium/Lanthanide Separation Flowsheet Using Sodium Bismuthate

    SciTech Connect

    Jack Law; Bruce Mincher; Troy Garn; Mitchell Greenhalgh; Nicholas Schmitt; Veronica Rutledge

    2014-04-01

    The separation of Am from the lanthanides and curium is a key step in proposed advanced fuel cycle scenarios. The partitioning and transmutation of Am is desirable to minimize the long-term heat load of material interred in a future high-level waste repository. A separation process amenable to process scale-up remains elusive. Given only subtle chemistry differences within and between the ions of the trivalent actinide and lanthanide series this separation is challenging ; however, higher oxidation states of americium can be prepared using sodium bismuthate and separated via solvent extraction using diamylamylphosphonate (DAAP) extraction. Among the other trivalent metals only Ce is also oxidized and extracted. Due to the long-term instability of Am(VI) , the loaded organic phase is readily selectively stripped to partition the actinide to a new acidic aqueous phase. Batch extraction distribution ratio measurements were used to design a flowsheet to accomplish this separation. Additionally, crossflow filtration was investigated as a method to filter the bismuthate solids from the feed solution prior to extraction. Results of the filtration studies, flowsheet development work and flowsheet performance testing using a centrifugal contactor are detailed.

  2. HYBRID SULFUR CYCLE FLOWSHEETS FOR HYDROGEN PRODUCTION USING HIGH-TEMPERATURE GAS-COOLED REACTORS

    SciTech Connect

    Gorensek, M.

    2011-07-06

    Two hybrid sulfur (HyS) cycle process flowsheets intended for use with high-temperature gas-cooled reactors (HTGRs) are presented. The flowsheets were developed for the Next Generation Nuclear Plant (NGNP) program, and couple a proton exchange membrane (PEM) electrolyzer for the SO2-depolarized electrolysis step with a silicon carbide bayonet reactor for the high-temperature decomposition step. One presumes an HTGR reactor outlet temperature (ROT) of 950 C, the other 750 C. Performance was improved (over earlier flowsheets) by assuming that use of a more acid-tolerant PEM, like acid-doped poly[2,2'-(m-phenylene)-5,5'-bibenzimidazole] (PBI), instead of Nafion{reg_sign}, would allow higher anolyte acid concentrations. Lower ROT was accommodated by adding a direct contact exchange/quench column upstream from the bayonet reactor and dropping the decomposition pressure. Aspen Plus was used to develop material and energy balances. A net thermal efficiency of 44.0% to 47.6%, higher heating value basis is projected for the 950 C case, dropping to 39.9% for the 750 C case.

  3. Characterization of radiolytically generated degradation products in the strip section of a TRUEX flowsheet

    SciTech Connect

    Dean R. Peterman; Lonnie G. Olson; Gary S. Groenewold; Rocklan G. McDowell; Richard D. Tillotson; Jack D. Law

    2013-08-01

    This report presents a summary of the work performed to meet the FCRD level 2 milestone M3FT-13IN0302053, “Identification of TRUEX Strip Degradation.” The INL radiolysis test loop has been used to identify radiolytically generated degradation products in the strip section of the TRUEX flowsheet. These data were used to evaluate impact of the formation of radiolytic degradation products in the strip section upon the efficacy of the TRUEX flowsheet for the recovery of trivalent actinides and lanthanides from acidic solution. The nominal composition of the TRUEX solvent used in this study is 0.2 M CMPO and 1.4 M TBP dissolved in n-dodecane and the nominal composition of the TRUEX strip solution is 1.5 M lactic acid and 0.050 M diethylenetriaminepentaacetic acid. Gamma irradiation of a mixture of TRUEX process solvent and stripping solution in the test loop does not adversely impact flowsheet performance as measured by stripping americium ratios. The observed increase in americium stripping distribution ratios with increasing absorbed dose indicates the radiolytic production of organic soluble degradation compounds.

  4. Flowsheet modifications for dissolution of sand, slag, and crucible residues in the F-canyon dissolvers

    SciTech Connect

    Rudisill, T.S.; Karraker, D.G.; Graham, F.R.

    1997-12-01

    An initial flowsheet for the dissolution of sand, slag, and crucible (SS{ampersand}C) was developed for the F- Canyon dissolvers as an alternative to dissolution in FB-Line. In that flowsheet, the sand fines were separated from the slag chunks and crucible fragments. Those two SS{ampersand}C streams were packaged separately in mild-steel cans for dissolution in the 6.4D dissolver. Nuclear safety constraints limited the dissolver charge to approximately 350 grams of plutonium in two of the three wells of the dissolver insert and required 0.23M (molar) boron as a soluble neutron poison in the 9.3M nitric acid/0.013M fluoride dissolver solution. During the first dissolution of SS{ampersand}C fines, it became apparent that a significant amount of the plutonium charged to the 6.4D dissolver did not dissolve in the time predicted by previous laboratory experiments. The extended dissolution time was attributed to fluoride complexation by boron. An extensive research and development (R{ampersand}D) program was initiated to investigate the dissolution chemistry and the physical configuration of the dissolver insert to understand what flowsheet modifications were needed to achieve a viable dissolution process.

  5. Nitrosation of Nigerian medicinal plant preparations under 'chemical' and 'simulated' gastric conditions.

    PubMed

    Atawodi, S E; Lamorde, A G; Spiegelhalder, B; Preussmann, R

    1995-01-01

    Preparations of some tropical plants of medicinal importance, collected from the savannah vegetational belt of Nigeria, were nitrosated and analysed for volatile N-nitrosamines formed under chemical and simulated gastric conditions. N-Nitrosamines were determined on a Thermal Energy Analyser following gas chromatographic separation. Mean concentrations of N-nitrosodimethylamine (NDMA) in the range of 7 to 58 ppb and N-nitrosodiethylamine (NDEA) in the range of 23 to 26 ppb were formed in 31 and 7%, respectively, of the preparations using artificial gastric juice (simulated gastric condition). Under chemically optimal conditions, relatively high levels of NDMA (72-2008 ppb), NDEA (23-1528 ppb) and N-nitrosopyrrolidine (20-405 ppb) were formed in 100, 75 and 32% of the preparations, respectively; N-nitrosomethylethylamine, N-nitrosodibutylamine and N-nitrosomorpholine were formed in fewer preparations. These findings suggest that the endogenous formation of N-nitroso compounds from precursors present in medicinal plants might be another source of human exposure to environmental carcinogens in Nigeria and other developing countries. PMID:7821876

  6. Purification characteristics of pothos for airborne chemicals in growing conditions and its evaluation

    NASA Astrophysics Data System (ADS)

    Sawada, Ayako; Oyabu, Takashi

    Plants have a purification capability to various kinds of airborne chemicals. The capability largely depends on the growing conditions of the plant. In this study, the capabilities of the plants growing in the following three conditions were examined: (a) put the subjective plant in a bowl of tap water, (b) put the one in a pot of growing water for over 1 year and (c) in the pot-soil. The room temperature and light intensity were changed in the experiments. As a result, it became obvious that the capability to formaldehyde varied in some degree according to room temperature. The capability decreased linearly in 12-25 °C in the case of (a), it did not change largely in the case of (b) and it indicated maximum value at 21 °C in the case of (c). The temperature belonged to optimal growth range of the plant. The capability-order is as follows: (a)<(b)<(c). The capability increased as the light intensity increased in each growth-condition. The capabilities to acetone, toluene and xylene were also examined. It became obvious that the capability became lower as the molecular weight of the chemical became larger.

  7. Salinity effect on mechanical dewatering of sludge with and without chemical conditioning.

    PubMed

    Lo IMC; Lai, K C; Chen, G H

    2001-12-01

    The salinity levels of wastewater and sludge are relatively high in some coastal cities as they may use saline water for toilet flushing, and as such,the sludge dewaterability can be affected by it. The salinity effect on sludge dewaterability was therefore investigated through experimental testing of specific resistance in filtration (SRF), time to filter (TTF), and final solid content of sludge. SRF and TTF were determined using Buchner funnel tests. The final solid content was estimated by centrifuging the sludge at four levels of rotational speed. Sludge with three salinity levels (5,000, 10,000 and 20,000 ppm) were considered in this study. Coagulants such as alum, iron(II) sulfate, and organic polyelectrolytes were added to the sludgetostudythe dewaterability of such sludge with chemical conditioning. Experimental results show that doubling the salinity level of the sludge from 10,000 to 20,000 ppm shows not much change in SRF and TTF. Compared with the sludge without chemical conditioning, the addition of the coagulants to the sludge at a salinity level of 5,000 ppm drastically reduces its SRF and TTF. However, sludge with and without chemical conditioning at a salinity of 20,000 ppm has similar SRF and TTF. The final solid content of sludge increases almost linearly with salinity. Among the coagulants used in this study, the cationic polyelectrolyte is found to be better in improving sludge dewaterability, while iron(II) sulfate performs slightly better in enhancing the final solid content of the sludge. PMID:11770773

  8. Sludge Washing And Demonstration Of The DWPF Flowsheet In The SRNL Shielded Cells For Sludge Batch 8 Qualification

    SciTech Connect

    Pareizs, J. M.; Crawford, C. L.

    2013-04-26

    The current Waste Solidification Engineering (WSE) practice is to prepare sludge batches in Tank 51 by transferring sludge from other tanks to Tank 51. Tank 51 sludge is washed and transferred to Tank 40, the current Defense Waste Processing Facility (DWPF) feed tank. Prior to transfer of Tank 51 to Tank 40, the Savannah River National Laboratory (SRNL) typically simulates the Tank Farm and DWPF processes using a Tank 51 sample (referred to as the qualification sample). WSE requested the SRNL to perform characterization on a Sludge Batch 8 (SB8) sample and demonstrate the DWPF flowsheet in the SRNL shielded cells for SB8 as the final qualification process required prior to SB8 transfer from Tank 51 to Tank 40. A 3-L sample from Tank 51 (the SB8 qualification sample; Tank Farm sample HTF-51-12-80) was received by SRNL on September 20, 2012. The as-received sample was characterized prior to being washed. The washed material was further characterized and used as the material for the DWPF process simulation including a Sludge Receipt and Adjustment Tank (SRAT) cycle, a Slurry Mix Evaporator (SME) cycle, and glass fabrication and chemical durability measurements.

  9. Optimizing chemical conditioning for odour removal of undigested sewage sludge in drying processes.

    PubMed

    Vega, Esther; Monclús, Hèctor; Gonzalez-Olmos, Rafael; Martin, Maria J

    2015-03-01

    Emission of odours during the thermal drying in sludge handling processes is one of the main sources of odour problems in wastewater treatment plants. The objective of this work was to assess the use of the response surface methodology as a technique to optimize the chemical conditioning process of undigested sewage sludges, in order to improve the dewaterability, and to reduce the odour emissions during the thermal drying of the sludge. Synergistic effects between inorganic conditioners (iron chloride and calcium oxide) were observed in terms of sulphur emissions and odour reduction. The developed quadratic models indicated that optimizing the conditioners dosage is possible to increase a 70% the dewaterability, reducing a 50% and 54% the emission of odour and volatile sulphur compounds respectively. The optimization of the conditioning process was validated experimentally. PMID:25438118

  10. Real-time detection of concealed chemical hazards under ambient light conditions using Raman spectroscopy.

    PubMed

    Cletus, Biju; Olds, William; Fredericks, Peter M; Jaatinen, Esa; Izake, Emad L

    2013-07-01

    Current concerns regarding terrorism and international crime highlight the need for new techniques for detecting unknown and hazardous substances. A novel Raman spectroscopy-based technique, spatially offset Raman spectroscopy (SORS), was recently devised for noninvasively probing the contents of diffusely scattering and opaque containers. Here, we demonstrate a modified portable SORS sensor for detecting concealed substances in-field under different background lighting conditions. Samples including explosive precursors, drugs, and an organophosphate insecticide (chemical warfare agent surrogate) were concealed inside diffusely scattering packaging including plastic, paper, and cloth. Measurements were carried out under incandescent and fluorescent light as well as under daylight to assess the suitability of the probe for different real-life conditions. In each case, it was possible to identify the substances against their reference Raman spectra in less than 1 min. The developed sensor has potential for rapid detection of concealed hazardous substances in airports, mail distribution centers, and customs checkpoints. PMID:23692353

  11. Combined Micro-chemical and Micro-structural Analysis of New Minerals Representing Extreme Conditions

    NASA Astrophysics Data System (ADS)

    Ma, C.; Tschauner, O. D.

    2015-12-01

    Recent improvements in micro-chemical analysis in combination with novel tools for micrometer-scale structural analysis of minerals from synchrotron X-ray diffraction open a pathway towards studies of mineral paragenesis that were previously not or barely accessible. Often mineral assemblies that represent extreme conditions also pose extreme challenges to analysis: very small size scale, complex matrix, minor amounts of material. Examples of such extreme, but also quite relevant environments are: a) High pressure shock-metamorphic minerals in meteorites and terrestrial impact sites, b) inclusions in diamonds from the deep mantle, c) ultrarefractory phases in Ca-Al-inlcusions from the solar nebula, d) presolar condensates. We show how a combination of synchrotron-based structural and semi-quantitative chemical techniques, with electron-microscopy based high-resolution imaging and fully quantitative chemical analysis and qualitative structural identification establish a powerful tool for discovery and characterization of important and interesting new minerals on micron- to submicron size scale.

  12. Combined physical and chemical methods to control lesser mealworm beetles under laboratory conditions.

    PubMed

    Wolf, Jônatas; Potrich, Michele; Lozano, Everton R; Gouvea, Alfredo; Pegorini, Carla S

    2015-06-01

    The lesser mealworm beetle, Alphitobius diaperinus (Panzer) (Coleoptera: Tenebrionidae), is an important insect pest. The insect acts as a disease vector and reservoir, negatively affecting the health of birds and humans, and harming poultry husbandry. Controlling the lesser mealworm is generally based on using synthetic chemical insecticides, which are sometimes ineffective, and is limited due to market concerns regarding the toxicity of chemical residues in food products. In this context, the present study aimed to evaluate the potential for the combination of physical and chemical methods to control A. diaperinus. Bioassays were conducted using poultry bedding and known populations of beetle adults and larvae. The treatments consisted of the isolated application of 400 g/m2 hydrated lime; 20% added moisture (distilled water); temperature increase to 45°C; an insecticide composed of cypermethrin, chlorpyrifos, and citronellal; and a combination of these factors. Beetle mortality was measured at 7 and 10 d of treatment. The hydrated lime and moisture treatments alone did not control A. diaperinus. Raising the temperature of the poultry bedding to 45°C effectively controlled both larvae (90±6%) and adults (90±4%). The use of insecticide provided adequate control of A. diaperinus in the conditions of the bioassay (93±2% and 68±5% for adults and larvae, respectively). The combination of the studied factors led to the total control of larvae and adults after 7 d of treatment. PMID:25834245

  13. Effects of biomass types and carbonization conditions on the chemical characteristics of hydrochars.

    PubMed

    Cao, Xiaoyan; Ro, Kyoung S; Libra, Judy A; Kammann, Claudia I; Lima, Isabel; Berge, Nicole; Li, Liang; Li, Yuan; Chen, Na; Yang, John; Deng, Baolin; Mao, Jingdong

    2013-10-01

    Effects of biomass types (bark mulch versus sugar beet pulp) and carbonization processing conditions (temperature, residence time, and phase of reaction medium) on the chemical characteristics of hydrochars were examined by elemental analysis, solid-state ¹³C NMR, and chemical and biochemical oxygen demand measurements. Bark hydrochars were more aromatic than sugar beet hydrochars produced under the same processing conditions. The presence of lignin in bark led to a much lower biochemical oxygen demand (BOD) of bark than sugar beet and increasing trends of BOD after carbonization. Compared with those prepared at 200 °C, 250 °C hydrochars were more aromatic and depleted of carbohydrates. Longer residence time (20 versus 3 h) at 250 °C resulted in the enrichment of nonprotonated aromatic carbons. Both bark and sugar beet pulp underwent deeper carbonization during water hydrothermal carbonization than during steam hydrothermal carbonization (200 °C, 3 h) in terms of more abundant aromatic C but less carbohydrate C in water hydrochars. PMID:24004410

  14. Physico-chemical characterization of steel slag. Study of its behavior under simulated environmental conditions.

    PubMed

    Navarro, Carla; Díaz, Mario; Villa-García, María A

    2010-07-15

    The chemical and mineralogical composition of steel slag produced in two ArcelorMittal steel plants located in the North of Spain, as well as the study of the influence of simulated environmental conditions on the properties of the slag stored in disposal areas, was carried out by elemental chemical analysis, XRF, X-ray diffraction, thermal analysis, and scanning electron microscopy with EDS analyzer. Spectroscopic characterization of the slag was also performed by using FTIR spectroscopy. Due to the potential uses of the slag as low cost adsorbent for water treatment and pollutants removal, its detailed textural characterization was carried out by nitrogen adsorption-desorption at 77 K and mercury intrusion porosimetry. The results show that the slag is a crystalline heterogeneous material whose main components are iron oxides, calcium (magnesium) compounds (hydroxide, oxide, silicates, and carbonate), elemental iron, and quartz. The slags are porous materials with specific surface area of 11 m(2)g(-1), containing both mesopores and macropores. Slag exposure to simulated environmental conditions lead to the formation of carbonate phases. Carbonation reduces the leaching of alkaline earth elements as well as the release of the harmful trace elements Cr (VI) and V. Steel slags with high contents of portlandite and calcium silicates are potential raw materials for CO(2) long-term storage. PMID:20568743

  15. Role of roasting conditions in the profile of volatile flavor chemicals formed from coffee beans.

    PubMed

    Moon, Joon-Kwan; Shibamoto, Takayuki

    2009-07-01

    The volatile chemicals in dichloromethane extracts from green coffee beans, roasted at 230 degrees C for 12 min (light), at 240 degrees C for 14 min (medium), at 250 degrees C for 17 min (city), or at 250 degrees C for 21 min (French), were analyzed by gas chromatography and gas chromatography-mass spectrometry. Among the 52 volatile compounds identified, the major compounds were 5-hydroxymethylfurfural, furfuryl alcohol, and 6-methyl-3,5-dihydroxy-4H-pyran-4-one in light-roasted beans; furfuryl alcohol, 5-hydroxymethylfurfural, and gamma-butyrolactone in medium-roasted beans; furfuryl alcohol, gamma-butyrolactone, and 2-acetylpyrrole in city-raosted beans; and gamma-butyrolactone, furfuryl alcohol, and catechol in French-roasted beans. Furfural derivatives and furanones were yielded in relatively high concentrations under mild roasting conditions and then reduced at higher roasting intensities. More pyridines and pyrroles were formed by high roasting intensities than by mild roasting intensities. Chlorogenic acid degradation products, phenols, and a lactone were produced more by high roasting intensities than by low roasting intensities. The results of the present study suggest that controlling the roasting conditions according to the formation of particular chemicals can prepare a roasted coffee with preferable flavor. PMID:19579294

  16. An evaluation of the chemical, radiological, and ecological conditions of West Lake on the Hanford site

    SciTech Connect

    Poston, T.M.; Price, K.L.; Newcomer, D.R.

    1991-03-01

    West Lake and its immediate surrounding basin represent a unique habitat that is dominated by highly saline water and soil. The basin offers a valuable research site for studies of a rare and complex wetland area in the desert. This report is an evaluation of the chemical, radiological, and ecological conditions at West Lake and describes how ground water influences site properties. The scope of this evaluation consisted of a sampling program in 1989 and a review of data from the perspective of assessing the impact of Hanford Site operations on the physical, chemical, and ecological conditions of West Lake and its surrounding basin. The water level in West Lake fluctuates in relation to changes in the water table. The connection between West Lake and ground water is also supported by the presence of {sup 3}H and {sup 99}Tc in the ground water and in the lake. There are relatively high concentrations of uranium in West Lake; the highest concentrations are found in the northernmost isolated pool. Analyses of water, sediment, vegetation, and soil indicate possible shifts of isotropic ratios that indicate a reduction of {sup 235}U. Uranium-236 was not detected in West Lake water; its presence would indicate neutron-activated {sup 235}U from fuel reprocessing at Hanford. Trace metals are found at elevated concentrations in West Lake. Arsenic, chromium, copper, and zinc were found at levels in excess of US Environmental Protection Agency water quality criteria. Levels of radiological and chemical contamination in the West Lake basin are relatively low. Concentrations of fission isotopes exceed those that could be explained by atmospheric fallout, but fall short of action levels for active waste management areas. 31 refs., 8 figs., 18 tabs.

  17. A continuum analysis of chemical nonequilibrium under hypersonic low-density flight conditions

    NASA Technical Reports Server (NTRS)

    Gupta, R. N.

    1986-01-01

    Results of employing the continuum model of Navier-Stokes equations under the low-density flight conditions are presented. These results are obtained with chemical nonequilibrium and multicomponent surface slip boundary conditions. The conditions analyzed are those encountered by the nose region of the Space Shuttle Orbiter during reentry. A detailed comparison of the Navier-Stokes (NS) results is made with the viscous shock-layer (VSL) and direct simulation Monte Carlo (DSMC) predictions. With the inclusion of new surface-slip boundary conditions in NS calculations, the surface heat transfer and other flowfield quantities adjacent to the surface are predicted favorably with the DSMC calculations from 75 km to 115 km in altitude. This suggests a much wider practical range for the applicability of Navier-Stokes solutions than previously thought. This is appealing because the continuum (NS and VSL) methods are commonly used to solve the fluid flow problems and are less demanding in terms of computer resource requirements than the noncontinuum (DSMC) methods.

  18. Characterizing summertime chemical boundary conditions for airmasses entering the US West Coast

    NASA Astrophysics Data System (ADS)

    Pfister, G. G.; Parrish, D.; Worden, H.; Emmons, L. K.; Edwards, D. P.; Wiedinmyer, C.; Diskin, G. S.; Huey, G.; Oltmans, S. J.; Thouret, V.; Weinheimer, A.; Wisthaler, A.

    2010-11-01

    The objective of this study is to analyze the pollution inflow into California during summertime and how it impacts surface air quality through combined analysis of a suite of observations and global and regional models. The focus is on the transpacific pollution transport investigated by the NASA Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS) mission in June 2008. Additional observations include satellite retrievals of carbon monoxide and ozone by the EOS Aura Tropospheric Emissions Spectrometer (TES), aircraft measurements from the MOZAIC program and ozonesondes. We compare chemical boundary conditions (BC) from the MOZART-4 global model, which are commonly used in regional simulations, with measured concentrations to quantify both the accuracy of the model results and the variability in pollution inflow. Both observations and model reflect a large variability in pollution inflow on temporal and spatial scales, but the global model captures only about half of the observed free tropospheric variability. Model tracer contributions show a large contribution from Asian emissions in the inflow. Recirculation of local US pollution can impact chemical BC, emphasizing the importance of consistency between the global model simulations used for BC and the regional model in terms of emissions, chemistry and transport. Aircraft measurements in the free troposphere over California show similar concentration range, variability and source contributions as free tropospheric air masses over ocean, but caution has to be taken that local pollution aloft is not misinterpreted as inflow. A flight route specifically designed to sample boundary conditions during ARCTAS-CARB showed a prevalence of plumes transported from Asia and thus may not be fully representative for average inflow conditions. Sensitivity simulations with a regional model with altered BCs show that the temporal variability in the pollution inflow does impact modeled

  19. Characterizing summertime chemical boundary conditions for airmasses entering the US West Coast

    NASA Astrophysics Data System (ADS)

    Pfister, G. G.; Parrish, D. D.; Worden, H.; Emmons, L. K.; Edwards, D. P.; Wiedinmyer, C.; Diskin, G. S.; Huey, G.; Oltmans, S. J.; Thouret, V.; Weinheimer, A.; Wisthaler, A.

    2011-02-01

    The objective of this study is to analyze the pollution inflow into California during summertime and how it impacts surface air quality through combined analysis of a suite of observations and global and regional models. The focus is on the transpacific pollution transport investigated by the NASA Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS) mission in June 2008. Additional observations include satellite retrievals of carbon monoxide and ozone by the EOS Aura Tropospheric Emissions Spectrometer (TES), aircraft measurements from the MOZAIC program and ozonesondes. We compare chemical boundary conditions (BC) from the MOZART-4 global model, which are commonly used in regional simulations, with measured concentrations to quantify both the accuracy of the model results and the variability in pollution inflow. Both observations and model reflect a large variability in pollution inflow on temporal and spatial scales, but the global model captures only about half of the observed free tropospheric variability. Model tracer contributions show a large contribution from Asian emissions in the inflow. Recirculation of local US pollution can impact chemical BC, emphasizing the importance of consistency between the global model simulations used for BC and the regional model in terms of emissions, chemistry and transport. Aircraft measurements in the free troposphere over California show similar concentration ranges, variability and source contributions as free tropospheric air masses over ocean, but caution has to be taken that local pollution aloft is not misinterpreted as inflow. A flight route specifically designed to sample boundary conditions during ARCTAS-CARB showed a prevalence of plumes transported from Asia and thus may not be fully representative for average inflow conditions. Sensitivity simulations with a regional model with altered BCs show that the temporal variability in the pollution inflow does impact modeled

  20. Natural Colloid Mobilization in Unsaturated Hanford Coarse Sand Under Transient Flow and Transient Chemical Conditions

    NASA Astrophysics Data System (ADS)

    Cheng, T.; Saiers, J. E.

    2007-12-01

    Colloid-sized clay, carbonate, and metal oxide particles are ubiquitous in the vadose zone and strongly adsorb dissolved contaminants such as metals and radionuclides. Under certain conditions, colloid particles are readily mobilized (released) into pore water and travel in a nearly conservative fashion and thus can facilitate the transport of contaminants. Although much progress has been made toward identifying and modeling colloid mobilization and transport processes in ideal, homogeneous systems, our understanding of the phenomenon in non-ideal, heterogeneous systems is still limited. We investigated natural colloid mobilization and transport in laboratory columns packed with Hanford Coarse Sand, a heterogeneous natural sediment. Our major focus was the role of transient flow and transient chemical conditions on colloid release and transport in unsaturated media. We found that a moving air-water interface had the greatest effects on the mobilization of colloid, and up to ~1000 mg/L of colloid was mobilized during column drainage at an ionic strength of 2 mM. An increase in flow rate or decrease in ionic strength also mobilized colloids. A model that accounts for transient pore water flow, colloid transport, and mass transfer in unsaturated media was developed to describe colloid mobilization in our column experiments. Both our experimental and modeling results showed the important role of moving air-water interfaces, changes in moisture content, and changes in ionic strength in mobilizing natural colloids in heterogeneous natural sediments. This work has contributed to our knowledge of colloid and colloid-associated contaminant mobilization in real vadose-zone environments under transient flow and transient chemical conditions.

  1. Interpopulational Variations in Sexual Chemical Signals of Iberian Wall Lizards May Allow Maximizing Signal Efficiency under Different Climatic Conditions

    PubMed Central

    2015-01-01

    Sexual signals used in intraspecific communication are expected to evolve to maximize efficacy under a given climatic condition. Thus, chemical secretions of lizards might evolve in the evolutionary time to ensure that signals are perfectly tuned to local humidity and temperature conditions affecting their volatility and therefore their persistence and transmission through the environment. We tested experimentally whether interpopulational altitudinal differences in chemical composition of femoral gland secretions of male Iberian wall lizards (Podarcis hispanicus) have evolved to maximize efficacy of chemical signals in different environmental conditions. Chemical analyses first showed that the characteristics of chemical signals of male lizards differed between two populations inhabiting environments with different climatic conditions in spite of the fact that these two populations are closely related genetically. We also examined experimentally whether the temporal attenuation of the chemical stimuli depended on simulated climatic conditions. Thus, we used tongue-flick essays to test whether female lizards were able to detect male scent marks maintained under different conditions of temperature and humidity by chemosensory cues alone. Chemosensory tests showed that chemical signals of males had a lower efficacy (i.e. detectability and persistence) when temperature and dryness increase, but that these effects were more detrimental for signals of the highest elevation population, which occupies naturally colder and more humid environments. We suggest that the abiotic environment may cause a selective pressure on the form and expression of sexual chemical signals. Therefore, interpopulational differences in chemical profiles of femoral secretions of male P. hispanicus lizards may reflect adaptation to maximize the efficacy of the chemical signal in different climates. PMID:26121693

  2. A flowsheet concept for an Am/Ln separation based on Am{sup VI} solvent extraction

    SciTech Connect

    Mincher, B.J.; Law, J.D.

    2013-07-01

    The separation of Am from the lanthanides and curium is a key step in proposed advanced fuel cycle scenarios. The partitioning and transmutation of Am is desirable to minimize the long-term radiotoxicity of material interred in a future high-level waste repository. However, a separation amenable to process scale-up remains elusive. Higher oxidation states of americium have recently been used to demonstrate solvent extraction-based separations using conventional fuel cycle ligands. Here, the successful partitioning of Am{sup VI} from the bulk of lanthanides and curium using diamyl-amyl-phosphonate (DAAP) extraction is reported. Due to the instability of Am{sup VI} in the organic phase it was readily selectively stripped to a new acidic aqueous phase to provide separation from co-extracted Ce{sup IV}. The use of NaBiO{sub 3} as an oxidant to separate Am from the lanthanides and Cm by solvent extraction has been successfully demonstrated on the bench scale. Based on these results, flowsheet concepts can be designed that result in 96 % Am recovery in the presence of a few percent of the remaining Cm and the lanthanides in two extraction contacts. Preliminary results also indicate that the DAAP extractant is robust toward γ- irradiation under realistic conditions of acidity and dissolved oxygen concentration.

  3. Aerosol physical, chemical and optical properties observed in the ambient atmosphere during haze pollution conditions

    NASA Astrophysics Data System (ADS)

    Li, Zhengqiang; Xie, Yisong; Li, Donghui; Li, Kaitao; Zhang, Ying; Li, Li; Lv, Yang; Qie, Lili; Xu, Hua

    Aerosol’s properties in the ambient atmosphere may differ significantly from sampling results due to containing of abundant water content. We performed sun-sky radiometer measurements in Beijing during 2011 and 2012 winter to obtain distribution of spectral and angular sky radiance. The measurements are then used to retrieve aerosol physical, chemical and optical properties, including single scattering albedo, size distribution, complex refractive indices and aerosol component fractions identified as black carbon, brown carbon, mineral dust, ammonium sulfate-like components and water content inside particle matters. We found that during winter haze condition aerosol is dominated by fine particles with center radius of about 0.2 micron. Fine particles contribute about 93% to total aerosol extinction of solar light, and result in serious decrease of atmospheric visibility during haze condition. The percentage of light absorption of haze aerosol can up to about 10% among its total extinction, much higher than that of unpolluted conditions, that causes significant radiative cooling effects suppressing atmospheric convection and dispersion of pollutants. Moreover, the average water content occupies about one third of the ambient aerosol in volume which suggests the important effect of ambient humidity in the formation of haze pollution.

  4. Chitosan use in chemical conditioning for dewatering municipal-activated sludge.

    PubMed

    Zemmouri, H; Mameri, N; Lounici, H

    2015-01-01

    This work aims to evaluate the potential use of chitosan as an eco-friendly flocculant in chemical conditioning of municipal-activated sludge. Chitosan effectiveness was compared with synthetic cationic polyelectrolyte Sedipur CF802 (Sed CF802) and ferric chloride (FeCl₃). In this context, raw sludge samples from Beni-Messous wastewater treatment plant (WWTP) were tested. The classic jar test method was used to condition sludge samples. Capillary suction time (CST), specific resistance to filtration (SRF), cakes dry solid content and filtrate turbidity were analyzed to determine filterability, dewatering capacity of conditioned sludge and the optimum dose of each conditioner. Data exhibit that chitosan, FeCl₃and Sed CF802 improve sludge dewatering. Optimum dosages of chitosan, Sed CF802 and FeCl₃allowing CST values of 6, 5 and 9 s, were found, respectively, between 2-3, 1.5-3 and 6 kg/t ds. Both polymers have shown faster water removal with more permeable sludge. SRF values were 0.634 × 10¹², 0.932 × 10¹² and 2 × 10¹² m/kg for Sed CF802, chitosan and FeCl₃respectively. A reduction of 94.68 and 87.85% of the filtrate turbidity was obtained with optimal dosage of chitosan and Sed CF802, respectively. In contrast, 54.18% of turbidity abatement has been obtained using optimal dosage of FeCl₃. PMID:25812088

  5. Assessment Of Chemical Dispersant Effectiveness In A Wave Tank Under Regular Non-Breaking And Breaking Wave Conditions

    EPA Science Inventory

    Current chemical dispersant effectiveness tests for product selection are commonly performed with bench-scale testing apparatus. However, for the assessment of oil dispersant effectiveness under real sea state conditions, test protocols are required to have hydrodynamic conditio...

  6. Potential dispositioning flowsheets for ICPP SNF and wastes

    SciTech Connect

    Olson, A.L.; Anderson, P.A.; Bendixsen, C.L.

    1995-11-01

    The Idaho Chemical Processing Plant (ICPP), located at the Idaho National Laboratory (INEL), has reprocessed irradiated nuclear fuels for the US Department of Energy (DOE) since 1953. This activity resulted mainly in the recovery of uranium and the management of the resulting wastes. The acidic radioactive high-level liquid waste was routinely stored in stainless steel tanks and then calcined to form a dry granular solid. The calcine is stored in stainless steel bins that are housed in underground concrete vaults. In April 1992, the DOE discontinued the practice of reprocessing irradiated nuclear fuels. This decision has left a legacy of 1.8 million gallons of radioactive liquid wastes (1.5 million gallons of radioactive sodium-bearing liquid wastes and 0.3 million gallons of high-level liquid waste), 3800 cubic meters of calcine waste, and 289 metric tons of heavy metal within unprocessed spent nuclear fuel (SNF) left in inventory at the ICPP. The nation`s radioactive waste policy has been established by the Nuclear Waste Policy Act (NWPA), which requires the final disposal of SNF and radioactive waste in accordance with US Environmental Protection Agency (EPA) and Nuclear Regulatory Commission (NRC) standards. In accordance with these regulations and other legal agreements between the State of Idaho and the DOE, the DOE must, among other requirements, (1) complete a final Environmental Impact Statement by April 30, 1995, (2) evaluate and test sodium-bearing waste pre-treatment technologies, (3) select the sodium-bearing and calcine waste pre-treatment technology, if necessary, by June 1, 1995, and (4) select a technology for converting calcined waste into an appropriate disposal form by June 1, 1995.

  7. Review and analysis of high temperature chemical reactions and the effect of non-equilibrium conditions

    NASA Technical Reports Server (NTRS)

    Johnson, R. E.

    1986-01-01

    Chemical reactions at high temperatures have been considered extensively because of their importance to the heating effects on re-entry of space vehicles. Data on these reactions however, are not abundant and even when found there are discrepancies in data collected by various investigators. In particular, data for recombination reactions are calculated from the dissociation reactions or vice versa through the equilibrium constant. This involves the use of the principle of detailed balancing. This principle is discussed in reference to conditions where it is valid as well as to those where it is not valid. Related topics that merit further study or for which applicable information was available are briefly mentioned in an appendix to this report.

  8. Carbon nanofiber aerogels for emergent cleanup of oil spillage and chemical leakage under harsh conditions

    PubMed Central

    Wu, Zhen-Yu; Li, Chao; Liang, Hai-Wei; Zhang, Yu-Ning; Wang, Xin; Chen, Jia-Fu; Yu, Shu-Hong

    2014-01-01

    To address oil spillage and chemical leakage accidents, the development of efficient sorbent materials is of global importance for environment and water source protection. Here we report on a new type of carbon nanofiber (CNF) aerogels as efficient sorbents for oil uptake with high sorption capacity and excellent recyclability. Importantly, the oil uptake ability of the CNF aerogels can be maintained over a wide temperature range, from liquid nitrogen temperature up to ca. 400°C, making them suitable for oil cleanup under harsh conditions. The outstanding sorption performance of CNF aerogels is associated with their unique physical properties, such as low density, high porosity, excellent mechanical stability, high hydrophobicity and superoleophilicity. PMID:24518262

  9. Chemical Quantification of Atomic-Scale EDS Maps under Thin Specimen Conditions

    DOE PAGESBeta

    Lu, Ping; Romero, Eric; Lee, Shinbuhm; MacManus-Driscoll, Judith L.; Jia, Quanxi

    2014-10-13

    We report our effort to quantify atomic-scale chemical maps obtained by collecting energy-dispersive X-ray spectra (EDS) using scanning transmission electron microscopy (STEM) (STEM-EDS). Under a thin specimen condition and when the EDS scattering potential is localized, the X-ray counts from atomic columns can be properly counted by fitting Gaussian peaks at the atomic columns, and can then be used for site-by-site chemical quantification. The effects of specimen thickness and X-ray energy on the Gaussian peak-width are investigated by using SrTiO3 (STO) as a model specimen. The relationship between the peak-width and spatial-resolution of an EDS map is also studied. Furthermore,more » the method developed by this work is applied to study a Sm-doped STO thin film and antiphase boundaries present within the STO film. We find that Sm atoms occupy both Sr and Ti sites but preferably the Sr sites, and Sm atoms are relatively depleted at the antiphase boundaries likely due to the effect of strain.« less

  10. Efficient and selective chemical transformations under flow conditions: The combination of supported catalysts and supercritical fluids

    PubMed Central

    Burguete, M Isabel; García-Verdugo, Eduardo

    2011-01-01

    Summary This paper reviews the current trends in the combined use of supported catalytic systems, either on solid supports or in liquid phases and supercritical fluids (scFs), to develop selective and enantioselective chemical transformations under continuous and semi-continuous flow conditions. The results presented have been selected to highlight how the combined use of those two elements can contribute to: (i) Significant improvements in productivity as a result of the enhanced diffusion of substrates and reagents through the interfaces favored by the scF phase; (ii) the long term stability of the catalytic systems, which also contributes to the improvement of the final productivity, as the use of an appropriate immobilization strategy facilitates catalyst isolation and reuse; (iii) the development of highly efficient selective or, when applicable, enantioselective chemical transformations. Although the examples reported in the literature and considered in this review are currently confined to a limited number of fields, a significant development in this area can be envisaged for the near future due to the clear advantages of these systems over the conventional ones. PMID:22043246

  11. A Molecular Dynamics Study of Chemical Reactions of Solid Pentaerythritol Tetranitrate at Extreme Conditions

    SciTech Connect

    Wu, C J; Manaa, M R; Fried, L E

    2006-05-30

    We have carried out density functional based tight binding (DFTB) molecular dynamics (MD) simulation to study energetic reactions of solid Pentaerythritol Tetranitrate (PETN) at conditions approximating the Chapman-Jouguet (CJ) detonation state. We found that the initial decomposition of PETN molecular solid is characterized by uni-molecular dissociation of the NO{sub 2}groups. Interestingly, energy release from this powerful high explosive was found to proceed in several stages. The large portion of early stage energy release was found to be associated with the formation of H{sub 2}O molecules within a few picoseconds of reaction. It took nearly four times as long for majority of CO{sub 2} products to form, accompanied by a slow oscillatory conversion between CO and CO{sub 2}. The production of N{sub 2} starts after NO{sub 2} loses its oxygen atoms to hydrogen or carbon atoms to form H{sub 2}O or CO. We identified many intermediate species that emerge and contribute to reaction kinetics, and compared our simulation with a thermo-chemical equilibrium calculation. In addition, a detailed chemical kinetics of formation of H{sub 2}O, CO, and CO{sub 2} were developed. Rate constants of formations of H{sub 2}O, CO{sub 2} and N{sub 2} were reported.

  12. Chemical Quantification of Atomic-Scale EDS Maps under Thin Specimen Conditions

    SciTech Connect

    Lu, Ping; Romero, Eric; Lee, Shinbuhm; MacManus-Driscoll, Judith L.; Jia, Quanxi

    2014-10-13

    We report our effort to quantify atomic-scale chemical maps obtained by collecting energy-dispersive X-ray spectra (EDS) using scanning transmission electron microscopy (STEM) (STEM-EDS). Under a thin specimen condition and when the EDS scattering potential is localized, the X-ray counts from atomic columns can be properly counted by fitting Gaussian peaks at the atomic columns, and can then be used for site-by-site chemical quantification. The effects of specimen thickness and X-ray energy on the Gaussian peak-width are investigated by using SrTiO3 (STO) as a model specimen. The relationship between the peak-width and spatial-resolution of an EDS map is also studied. Furthermore, the method developed by this work is applied to study a Sm-doped STO thin film and antiphase boundaries present within the STO film. We find that Sm atoms occupy both Sr and Ti sites but preferably the Sr sites, and Sm atoms are relatively depleted at the antiphase boundaries likely due to the effect of strain.

  13. Chemical evolution: The mechanism of the formation of adenine under prebiotic conditions

    PubMed Central

    Roy, Debjani; Najafian, Katayoun; von Ragué Schleyer, Paul

    2007-01-01

    Fundamental building blocks of life have been detected extraterrestrially, even in interstellar space, and are known to form nonenzymatically. Thus, the HCN pentamer, adenine (a base present in DNA and RNA), was first isolated in abiogenic experiments from an aqueous solution of ammonia and HCN in 1960. Although many variations of the reaction conditions giving adenine have been reported since then, the mechanistic details remain unexplored. Our predictions are based on extensive computations of sequences of reaction steps along several possible mechanistic routes. H2O- or NH3-catalyzed pathways are more favorable than uncatalyzed neutral or anionic alternatives, and they may well have been the major source of adenine on primitive earth. Our report provides a more detailed understanding of some of the chemical processes involved in chemical evolution, and a partial answer to the fundamental question of molecular biogenesis. Our investigation should trigger similar explorations of the detailed mechanisms of the abiotic formation of the remaining nucleic acid bases and other biologically relevant molecules. PMID:17951429

  14. INITIAL CHEMICAL AND RESERVOIR CONDITIONS AT LOS AZUFRES WELLHEAD POWER PLANT STARTUP

    SciTech Connect

    Kruger, P.; Semprini, L.; Verma, S.; Barragan, R.; Molinar, R.; Aragon, A.; Ortiz, J.; Miranda, C.

    1985-01-22

    One of the major concerns of electric utilities in installing geothermal power plants is not only the longevity of the steam supply, but also the potential for changes in thermodynamic properties of the resource that might reduce the conversion efficiency of the design plant equipment. Production was initiated at Los Azufres geothermal field with wellhead generators not only to obtain electric energy at a relatively early date, but also to acquire needed information about the resource so that plans for large central power plants could be finalized. Commercial electric energy production started at Los Azufres during the summer of 1982 with five 5-MWe wellhead turbine-generator units. The wells associated with these units had undergone extensive testing and have since been essentially in constant production. The Los Azufres geothermal reservoir is a complex structural and thermodynamic system, intersected by at least 4 major parallel faults and producing geothermal fluids from almost all water to all steam. The five wellhead generators are associated with wells of about 30%, 60%, and 100% steam fraction. A study to compile existing data on the chemical and reservoir conditions during the first two years of operation has been completed. Data have been compiled on mean values of wellhead and separator pressures, steam and liquid flowrates, steam fraction, enthalpy, and pertinent chemical components. The compilation serves both as a database of conditions during the start-up period and as an initial point to observe changes with continued and increased production. Current plans are to add additional wellhead generators in about two years followed by central power plants when the data have been sufficiently evaluated for optimum plant design. During the next two years, the data acquired at the five 5-MWe wellhead generator units can be compared to this database to observe any significant changes in reservoir behavior at constant production.

  15. Permafrost conditions in peatlands regulate magnitude, timing, and chemical composition of catchment dissolved organic carbon export.

    PubMed

    Olefeldt, David; Roulet, Nigel T

    2014-10-01

    Permafrost thaw in peatlands has the potential to alter catchment export of dissolved organic carbon (DOC) and thus influence downstream aquatic C cycling. Subarctic peatlands are often mosaics of different peatland types, where permafrost conditions regulate the hydrological setting of each type. We show that hydrological setting is key to observed differences in magnitude, timing, and chemical composition of DOC export between permafrost and nonpermafrost peatland types, and that these differences influence the export of DOC of larger catchments even when peatlands are minor catchment components. In many aspects, DOC export from a studied peatland permafrost plateau was similar to that of a forested upland catchment. Similarities included low annual export (2-3 g C m(-2) ) dominated by the snow melt period (~70%), and how substantial DOC export following storms required wet antecedent conditions. Conversely, nonpermafrost fens had higher DOC export (7 g C m(-2) ), resulting from sustained hydrological connectivity during summer. Chemical composition of catchment DOC export arose from the mixing of highly aromatic DOC from organic soils from permafrost plateau soil water and upland forest surface horizons with nonaromatic DOC from mineral soil groundwater, but was further modulated by fens. Increasing aromaticity from fen inflow to outlet was substantial and depended on both water residence time and water temperature. The role of fens as catchment biogeochemical hotspots was further emphasized by their capacity for sulfate retention. As a result of fen characteristics, a 4% fen cover in a mixed catchment was responsible for 34% higher DOC export, 50% higher DOC concentrations and ~10% higher DOC aromaticity at the catchment outlet during summer compared to a nonpeatland upland catchment. Expansion of fens due to thaw thus has potential to influence landscape C cycling by increasing fen capacity to act as biogeochemical hotspots, amplifying aquatic C cycling, and

  16. Development and testing of a SREX flowsheet for the partitioning of strontium and lead from simulated ICPP sodium-bearing waste

    SciTech Connect

    Law, J.D.; Wood, D.J.

    1996-11-01

    Laboratory experimentation has indicated that the SREX process is effective for partitioning {sup 90}Sr from acidic radioactive waste solutions located at the Idaho Chemical Processing Plant. Previous countercurrent flowsheet testing of the SREX process with simulated waste resulted in 99.98% removal of Sr. With this previous test, however, Pb was extracted by the SREX solvent and was not back-extracted in the dilute nitric acid strip section. The Pb concentration increased in the recycled solvent and in the aqueous phase of the strip section, resulting in the formation of a Pb precipitate. Subsequently, studies were initiated to identify alternative stripping agents which will selectively strip Sr and Pb from the SREX solvent. Based on the results of these studies, a countercurrent flow sheet was developed and tested in the 5.5-cm Centrifugal Contactor Mockup using simulated waste. The flowsheet tested consisted of an extraction section (0.15 M 4{prime},4{prime}(5)-di-(tert-butyldicyclohexo)-18-crown-6 and 1.2 M TBP in Isopar-L{reg_sign}), a 0.05 M nitric acid strip section for the removal of Sr from the SREX solvent, a 0.1 M ammonium citrate strip section for the removal of Pb from the SREX solvent, and a 2.0 M nitric acid equilibration section. The behavior of Sr, Pb, Al, Ca, Hg, Na, Zr, and H{sup +} was evaluated. The described flowsheet successfully extracted and selectively stripped Sr and Pb from the SBW simulant. Removal efficiencies of 97.9% and 99.91% were obtained for Sr and Pb, respectively. Essentially all of the extracted Sr (99.998%) and 1.9% of extracted Pb exited with the 0.05 M nitric acid strip product; whereas, 0.002% of the extracted Sr and 97.9% of the extracted Pb existed with the 0.1 M ammonium citrate strip product. Also, 95% of the Hg and 63% of the Zr were extracted by the SREX solvent.

  17. DWPF Flowsheet Studies with Simulants to Determine Modular Caustic Side Solvent Extraction Unit Solvent Partitioning and Verify Actinide Removal Process Incorporation Strategy

    SciTech Connect

    Herman, C

    2006-04-21

    The Actinide Removal Process (ARP) facility and the Modular Caustic Side Solvent Extraction Unit (MCU) are scheduled to begin processing salt waste in fiscal year 2007. A portion of the streams generated in the salt processing facilities will be transferred to the Defense Waste Processing Facility (DWPF) to be incorporated in the glass matrix. Before the streams are introduced, a combination of impact analyses and research and development studies must be performed to quantify the impacts on DWPF processing. The Process Science & Engineering (PS&E) section of the Savannah River National Laboratory (SRNL) was requested via Technical Task Request (TTR) HLW/DWPF/TTR-2004-0031 to evaluate the impacts on DWPF processing. Simulant Chemical Process Cell (CPC) flowsheet studies have been performed using previous composition and projected volume estimates for the ARP sludge/monosodium titanate (MST) stream. Due to changes in the flammability control strategy for DWPF for salt processing, the incorporation strategy for ARP has changed and additional ARP flowsheet tests were necessary to validate the new processing strategy. The last round of ARP testing included the incorporation of the MCU stream and identified potential processing issues with the MCU solvent. The identified issues included the potential carry-over and accumulation of the MCU solvent components in the CPC condensers and in the recycle stream to the Tank Farm. Therefore, DWPF requested SRNL to perform additional MCU flowsheet studies to better quantify the organic distribution in the CPC vessels. The previous MCU testing used a Sludge Batch 4 (SB4) simulant since it was anticipated that both of these facilities would begin salt processing during SB4 processing. The same sludge simulant recipe was used in this round of ARP and MCU testing to minimize the number of changes between the two phases of testing so a better comparison could be made. ARP and MCU stream simulants were made for this phase of testing

  18. Physical and chemical stability of expired fixed dose combination artemether-lumefantrine in uncontrolled tropical conditions

    PubMed Central

    Bate, Roger; Tren, Richard; Hess, Kimberly; Attaran, Amir

    2009-01-01

    Background New artemisinin combination therapies pose difficulties of implementation in developing and tropical settings because they have a short shelf-life (two years) relative to the medicines they replace. This limits the reliability and cost of treatment, and the acceptability of this treatment to health care workers. A multi-pronged investigation was made into the chemical and physical stability of fixed dose combination artemether-lumefantrine (FDC-ALU) stored under heterogeneous, uncontrolled African conditions, to probe if a shelf-life extension might be possible. Methods Seventy samples of expired FDC-ALU were collected from private pharmacies and malaria researchers in seven African countries. The samples were subjected to thin-layer chromatography (TLC), disintegration testing, and near infrared Raman spectrometry for ascertainment of active ingredients, tablet integrity, and chemical degradation of the tablet formulation including both active ingredients and excipients. Results Seventy samples of FDC-ALU were tested in July 2008, between one and 58 months post-expiry. 68 of 70 (97%) samples passed TLC, disintegration and Raman spectrometry testing, including eight samples that were post-expiry by 20 months or longer. A weak linear association (R2 = 0.33) was observed between the age of samples and their state of degradation relative to brand-identical samples on Raman spectrometry. Sixty-eight samples were retested in February 2009 using Raman spectrometry, between eight and 65 months post-expiry. 66 of 68 (97%) samples passed Raman spectrometry retesting. An unexpected observation about African drug logistics was made in three batches of FDC-ALU, which had been sold into the public sector at concessional pricing in accordance with a World Health Organization (WHO) agreement, and which were illegally diverted to the private sector where they were sold for profit. Conclusion The data indicate that FDC-ALU is chemically and physically stable well beyond

  19. Characterization of Neptunium Oxide Generated Using the HB-Line Phase II Flowsheet

    SciTech Connect

    Duffey, J

    2003-08-29

    Approximately 98 grams of neptunium(IV) oxide (NpO{sub 2}) were produced at the Savannah River Technology Center (SRTC) for use in gas generation tests to support the neptunium stabilization program at the Savannah River Site (SRS). The NpO{sub 2} was produced according to the anticipated HB-Line flowsheet consisting of anion exchange, oxalate precipitation, filtration, and calcination. Characterization of the NpO{sub 2} product to be used in gas generation tests included bulk and tap density measurements, X-ray diffraction, particle size distribution, specific surface area measurements, and moisture analysis.

  20. Plutonium purification cycle in centrifugal extractors: from flowsheet design to industrial operation

    SciTech Connect

    Baron, P.; Dinh, B.; Duhamet, J.; Drain, F.; Meze, F.; Lavenu, A.

    2008-07-01

    The extension of the UP2 plant at La Hague includes a new plutonium purification cycle using multistage centrifugal extractors to replace the previous cycle that used mixer/settler banks. This type of extractor is suitable for the treatment of fuel containing a high proportion of plutonium-238, as its short residence time limits solvent degradation. This paper deals with the research done to devise its flowsheet, the centrifugal extractors in which it is operated, as well as the feedback of six years of industrial operation.

  1. Atomistic Simulations of Chemical Reactivity of TATB Under Thermal and Shock Conditions

    SciTech Connect

    Manaa, M R; Reed, E J; Fried, L E

    2009-09-23

    The study of chemical transformations that occur at the reactive shock front of energetic materials provides important information for the development of predictive models at the grain-and continuum scales. A major shortcoming of current high explosives models is the lack of chemical kinetics data of the reacting explosive in the high pressure and temperature regimes. In the absence of experimental data, long-time scale atomistic molecular dynamics simulations with reactive chemistry become a viable recourse to provide an insight into the decomposition mechanism of explosives, and to obtain effective reaction rate laws. These rates can then be incorporated into thermo-chemical-hydro codes (such as Cheetah linked to ALE3D) for accurate description of the grain and macro scales dynamics of reacting explosives. In this talk, I will present quantum simulations of 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) crystals under thermal decomposition (high density and temperature) and shock compression conditions. This is the first time that condensed phase quantum methods have been used to study the chemistry of insensitive high explosives. We used the quantum-based, self-consistent charge density functional tight binding method (SCC{_}DFTB) to calculate the interatomic forces for reliable predictions of chemical reactions, and to examine electronic properties at detonation conditions for a relatively long time-scale on the order of several hundreds of picoseconds. For thermal decomposition of TATB, we conducted constant volume-temperature simulations, ranging from 0.35 to 2 nanoseconds, at {rho} = 2.87 g/cm{sup 3} at T = 3500, 3000, 2500, and 1500 K, and {rho} = 2.9 g/cm{sup 3} and 2.72 g/cm{sup 3}, at T = 3000 K. We also simulated crystal TATB's reactivity under steady overdriven shock compression using the multi-scale shock technique. We conducted shock simulations with specified shock speeds of 8, 9, and 10 km/s for up to 0.43 ns duration, enabling us to track the

  2. Molecules in interstellar clouds. [physical and chemical conditions of star formation and biological evolution

    NASA Technical Reports Server (NTRS)

    Irvine, W. M.; Hjalmarson, A.; Rydbeck, O. E. H.

    1981-01-01

    The physical conditions and chemical compositions of the gas in interstellar clouds are reviewed in light of the importance of interstellar clouds for star formation and the origin of life. The Orion A region is discussed as an example of a giant molecular cloud where massive stars are being formed, and it is pointed out that conditions in the core of the cloud, with a kinetic temperature of about 75 K and a density of 100,000-1,000,000 molecules/cu cm, may support gas phase ion-molecule chemistry. The Taurus Molecular Clouds are then considered as examples of cold, dark, relatively dense interstellar clouds which may be the birthplaces of solar-type stars and which have been found to contain the heaviest interstellar molecules yet discovered. The molecular species identified in each of these regions are tabulated, including such building blocks of biological monomers as H2O, NH3, H2CO, CO, H2S, CH3CN and H2, and more complex species such as HCOOCH3 and CH3CH2CN.

  3. Arsenic mobility in soils contaminated with metallurgical wastes as a function of variable chemical conditions

    NASA Astrophysics Data System (ADS)

    Garcia Payne, D. G.; Villalobos, M.; Ceniceros, A.; Lopez, J. L.; Gutierrez, M.

    2008-12-01

    Arsenic is a pervasive contaminant of natural aqueous systems, such as groundwater and soils, its sources being both natural and anthropogenic. The present investigation was performed on soils contaminated with residues from ore processing activities and revealed the presence of arsenate [As(V)] species with a very low mobility, through natural attenuation processes. The stability of this attenuation was investigated by varying two specific equilibrium chemical conditions: pH and presence of bicarbonate ions. One-unit changes in equilibrium pH generally caused small increases in As mobility, whereas the presence of bicarbonate ions considerably increased this mobility. The results were compared to thermodinamic simulations of equilibrium conditions using the total elemental composition of each individual soil, but excluding sorption reactions. Close matches between experimental data and simulations revealed the predominance of solubility-controlled As mobility via heavy-metal arsenate solid formation. Bicarbonate ions were found to be highly unsuitable for extraction of sorbed arsenate fractions due to indirect As release from solid arsenates, via heavy-metal carbonate precipitation processes.

  4. Chemical composition and quantitative relationship between meteorological condition and fine particles in Beijing.

    PubMed

    Wang, Jing-Li; Zhang, Yuan-Hang; Shao, Min; Liu, Xu-Lin; Zeng, Li-Min; Cheng, Cong-Lan; Xu, Xiao-Feng

    2004-01-01

    The recent year's monitor results of Beijing indicated that the pollution level of fine particles PM2.5 showed an increasing trend. To understand pollution characteristics of PM2.5 and its relationship with the meteorological conditions in Beijing, a one-year monitoring of PM2.5 mass concentration and correspondent meteorological parameters was performed in Beijing in 2001. The PM2.5 levels in Beijing were very high, the annual average PM2.5 concentration in 2001 was 7 times of the National Ambient Air Quality Standards proposed by US EPA. The major chemical compositions were organics, sulfate, crustals and nitrate. It was found that the mass concentrations of PM2.5 were influenced by meteorological conditions. The correlation between the mass concentrations of PM2.5 and the relative humidity was found. And the correlation became closer at higher relative humidity. And the mass concentrations of PM2.5 were negtive-correlated to wind speeds, but the correlation between the mass concentration of PM2.5 and wind speed was not good at stronger wind. PMID:15559829

  5. Dimethylglycine and chemically related amines tested for mutagenicity under potential nitrosation conditions.

    PubMed

    Hoorn, A J

    1989-04-01

    Dimethylglycine (DMG) and the chemically related amino acids glycine, sarcosine (monomethylglycine) and betaine (trimethylglycine) were tested in Salmonella typhimurium strain TA100 after treatment with sodium nitrite under acidic conditions using a modified Ames Salmonella/microsome assay as reported by Colman et al. (1980). The increase in the number of revertants observed both with and without metabolic activation was also induced in the control mixtures without adding the amines. From the subsequent testing of the individual components of the mixtures, we concluded that non-consumed nitrite was responsible for the mutagenic responses observed in the different reaction mixtures, and not the amines themselves. There were no consistent indications of mutagenic activity of the DMG test mixture as compared to the control mixture which exhibited both consistent mutagenic activity and a toxic effect which was not increased by the addition of DMG. In fact, DMG seemed to decrease the toxicity of the control reaction solution to the Salmonella which was clearly observed at the higher doses. DMG cannot be considered mutagenic under the test conditions employed. The same can be said of the other amino acids as well. PMID:2468082

  6. Surface studies of niobium chemically polished under conditions for superconducting radiofrequency cavity production

    SciTech Connect

    Hui Tian; Michael Kelley; Charles Reece

    2005-11-14

    The performance of niobium superconducting radiofrequency accelerator cavities is strongly impacted by the topmost several nanometers of the active (interior) surface, especially by the final surface conditioning treatments. We examined the effect of the most commonly employed treatment, buffered chemical polishing (BCP), on polycrystalline niobium sheet over a range of realistic solution flow rates using electron back scatter diffraction (EBSD), stylus profilometry, atomic force microscopy, laboratory XPS and synchrotron (variable photon energy) XPS, seeking to collect statistically significant data sets. We found that the predominant general surface orientation is (100), but others are also present and at the atomic-level details of surface plane orientation are more complex. The post-etch surface exhibits micron-scale roughness, whose extent does not change with treatment conditions. The outermost surface consists of a few-nm thick layer of niobium pentoxide, whose thickness increases with solution flow rate to a maximum of 1.3 - 1.4 times that resulting from static solution. The standard deviation of the roughness measurements is ?? 30% and that of the surface composition is ?? 5%.

  7. Using capillary electrophoresis to study the chemical conditions within cracks in aluminum alloys.

    PubMed

    Cooper, K R; Kelly, R G

    1999-07-30

    The environment-assisted cracking (EAC) susceptibility of some aluminum alloys used for airplane structural components currently limits their use in the peak strength condition. Understanding the mechanism of EAC will facilitate the development of crack-resistant alloys with optimum mechanical properties. One component towards understanding the fundamental processes responsible for EAC is a comprehensive knowledge of the chemical conditions within cracks. The present work uses capillary electrophoresis (CE) to quantify the crack chemistry in order to provide insight into the nature of the mechanism controlling cracking. The highly restricted geometry of cracks in metals means that a crack typically contains less than 10 microliters of solution. The high mass sensitivity combined with the inherently robust nature of CE makes it an ideal analytical technique for this application. Complicating factors in the accurate determination of the crack environment include high levels of sodium present from the test solution. Low sample volume and analyte matrix complexity necessitated the development of specific sampling, extraction and analysis methods. Analysis of the crack solutions in EAC-susceptible material revealed high levels of Al3+, Mg2+, Zn2+, and Cl- near the crack tip. Cations arise from the anodic dissolution of the alloy, whereas chloride ingress from the external environment occurs to maintain solution electroneutrality within the crack. In contrast, EAC-resistant material exhibited significantly lower concentrations of dissolution products. PMID:10457501

  8. Conditionally controlling nuclear trafficking in yeast by chemical-induced protein dimerization

    PubMed Central

    Xu, Tao; Johnson, Cole A; Gestwicki, Jason E; Kumar, Anuj

    2016-01-01

    We present here a protocol to conditionally control the nuclear trafficking of target proteins in yeast. In this system, rapamycin is used to heterodimerize two chimeric proteins. one chimera consists of a FK506-binding protein (FKBp12) fused to a cellular ‘address’ (nuclear localization signal or nuclear export sequence). the second chimera consists of a target protein fused to a fluorescent protein and the FKBp12-rapamycin-binding (FrB) domain from FKBp-12-rapamycin associated protein 1 (Frap1, also known as mtor). rapamycin induces dimerization of the FKBp12- and FrB-containing chimeras; these interactions selectively place the target protein under control of the cell address, thereby directing the protein into or out of the nucleus. By chemical-induced dimerization, protein mislocalization is reversible and enables the identification of conditional loss-of-function and gain-of-function phenotypes, in contrast to other systems that require permanent modification of the targeted protein. Yeast strains for this analysis can be constructed in 1 week, and the technique allows protein mislocalization within 15 min after drug treatment. PMID:21030958

  9. Oxidative weathering chemical migration under variably saturated conditions and supergene copper enrichment

    SciTech Connect

    Xu, Tianfu; Pruess, K.; Brimhall, G.

    1999-04-01

    Transport of oxygen gas from the land surface through an unsaturated zone has a strong influence on oxidative weathering processes. Oxidation of sulfide minerals such as pyrite (FeS{sub 2}), one of the most common naturally occurring minerals, is the primary source of acid drainage from mines and waste rock piles. Here we present a detailed numerical model of supergene copper enrichment that involves the oxidative weathering of pyrite (FeS{sub 2}) and chalcopyrite (CuFeS{sub 2}), and acidification that causes mobilization of metals in the unsaturated zone, with subsequent formation of enriched ore deposits of chalcocite (CuS) and covellite (Cu{sub 2}S) in the reducing conditions below the water table. We examine and identify some significant conceptual and computational issues regarding the oxidative weathering processes through the modeling tool. The dissolution of gaseous oxygen induced by the oxidation reduces oxygen partial pressure, as well as the total pressure of the gas phase. As a result, the gas flow is modified, then the liquid phase flow. Results indicate that this reaction effect on the fluid flow may not be important under ambient conditions, and gas diffusion can be a more important mechanism for oxygen supply than gas or liquid advection. Acidification, mobilization of metals, and alteration of primary minerals mostly take place in unsaturated zone (oxidizing), while precipitation of secondary minerals mainly occurs in saturated zone (reducing). The water table may be considered as an interface between oxidizing and reducing zones. Moving water table due to change of infiltration results in moving oxidizing zone and redistributing aqueous chemical constitutes and secondary mineral deposits. The oxidative weathering processes are difficult to model numerically, because concentrations of redox sensitive chemical species such as O{sub 2}(aq), SO{sub 4}{sup 2-} and HS{sup -} may change over tens of orders of magnitude between oxidizing and reducing

  10. Electric Current Activated Combustion Synthesis and Chemical Ovens Under Terrestrial and Reduced Gravity Conditions

    NASA Technical Reports Server (NTRS)

    Unuvar, C.; Fredrick, D.; Anselmi-Tamburini, U.; Manerbino, A.; Guigne, J. Y.; Munir, Z. A.; Shaw, B. D.

    2004-01-01

    Combustion synthesis (CS) generally involves mixing reactants together (e.g., metal powders) and igniting the mixture. Typically, a reaction wave will pass through the sample. In field activated combustion synthesis (FACS), the addition of an electric field has a marked effect on the dynamics of wave propagation and on the nature, composition, and homogeneity of the product as well as capillary flow, mass-transport in porous media, and Marangoni flows, which are influenced by gravity. The objective is to understand the role of an electric field in CS reactions under conditions where gravity-related effects are suppressed or altered. The systems being studied are Ti+Al and Ti+3Al. Two different ignition orientations have been used to observe effects of gravity when one of the reactants becomes molten. This consequentially influences the position and concentration of the electric current, which in turn influences the entire process. Experiments have also been performed in microgravity conditions. This process has been named Microgravity Field Activated Combustion Synthesis (MFACS). Effects of gravity have been demonstrated, where the reaction wave temperature and velocity demonstrate considerable differences besides the changes of combustion mechanisms with the different high currents applied. Also the threshold for the formation of a stable reaction wave is increased under zero gravity conditions. Electric current was also utilized with a chemical oven technique, where inserts of aluminum with minute amounts of tungsten and tantalum were used to allow observation of effects of settling of the higher density solid particles in liquid aluminum at the present temperature profile and wave velocity of the reaction.

  11. Four chemical methods of porcelain conditioning and their influence over bond strength and surface integrity

    PubMed Central

    Stella, João Paulo Fragomeni; Oliveira, Andrea Becker; Nojima, Lincoln Issamu; Marquezan, Mariana

    2015-01-01

    OBJECTIVE: To assess four different chemical surface conditioning methods for ceramic material before bracket bonding, and their impact on shear bond strength and surface integrity at debonding. METHODS: Four experimental groups (n = 13) were set up according to the ceramic conditioning method: G1 = 37% phosphoric acid etching followed by silane application; G2 = 37% liquid phosphoric acid etching, no rinsing, followed by silane application; G3 = 10% hydrofluoric acid etching alone; and G4 = 10% hydrofluoric acid etching followed by silane application. After surface conditioning, metal brackets were bonded to porcelain by means of the Transbond XP system (3M Unitek). Samples were submitted to shear bond strength tests in a universal testing machine and the surfaces were later assessed with a microscope under 8 X magnification. ANOVA/Tukey tests were performed to establish the difference between groups (α= 5%). RESULTS: The highest shear bond strength values were found in groups G3 and G4 (22.01 ± 2.15 MPa and 22.83 ± 3.32 Mpa, respectively), followed by G1 (16.42 ± 3.61 MPa) and G2 (9.29 ± 1.95 MPa). As regards surface evaluation after bracket debonding, the use of liquid phosphoric acid followed by silane application (G2) produced the least damage to porcelain. When hydrofluoric acid and silane were applied, the risk of ceramic fracture increased. CONCLUSIONS: Acceptable levels of bond strength for clinical use were reached by all methods tested; however, liquid phosphoric acid etching followed by silane application (G2) resulted in the least damage to the ceramic surface. PMID:26352845

  12. Soil structure, colloids, and chemical transport as affected by short-term reducing conditions: a laboratory study

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Upland soils in the Midwestern US often undergo reducing conditions when soils are temporally flooded during the spring and remain water saturated for days or weeks. Short-term reducing conditions change the chemistry of the soil and may affect soil structure and solution chemical transport. The eff...

  13. Phytoplankton communities of polar regions--Diversity depending on environmental conditions and chemical anthropopressure.

    PubMed

    Kosek, Klaudia; Polkowska, Żaneta; Żyszka, Beata; Lipok, Jacek

    2016-04-15

    The polar regions (Arctic and Antarctic) constitute up to 14% of the biosphere and offer some of the coldest and most arid Earth's environments. Nevertheless several oxygenic phototrophs including some higher plants, mosses, lichens, various algal groups and cyanobacteria, survive that harsh climate and create the base of the trophic relationships in fragile ecosystems of polar environments. Ecosystems in polar regions are characterized by low primary productivity and slow growth rates, therefore they are more vulnerable to disturbance, than those in temperate regions. From this reason, chemical contaminants influencing the growth of photoautotrophic producers might induce serious disorders in the integrity of polar ecosystems. However, for a long time these areas were believed to be free of chemical contamination, and relatively protected from widespread anthropogenic pressure, due their remoteness and extreme climate conditions. Nowadays, there is a growing amount of data that prove that xenobiotics are transported thousands of kilometers by the air and ocean currents and then they are deposed in colder regions and accumulate in many environments, including the habitats of marine and freshwater cyanobacteria. Cyanobacteria (blue green algae), as a natural part of phytoplankton assemblages, are globally distributed, but in high polar ecosystems they represent the dominant primary producers. These microorganisms are continuously exposed to various concentration levels of the compounds that are present in their habitats and act as nourishment or the factors influencing the growth and development of cyanobacteria in other way. The most common group of contaminants in Arctic and Antarctic are persistent organic pollutants (POPs), characterized by durability and resistance to degradation. It is important to determine their concentrations in all phytoplankton species cells and in their environment to get to know the possibility of contaminants to transfer to higher

  14. Effects of dehulling and storage conditions on cooking requirements and chemical composition of soybeans.

    PubMed

    Cabral, L C; Serna-Saldivar, S O; Tinsley, A M

    1995-03-01

    Changes in cooking requirements and chemical composition of whole and dehulled soybeans, stored in 2 different environments [25 degrees C /75% R.H. (Environment 1) and 38 degrees C /90% R.H. (Environment 2)], were studied. Rate of water absorption and solid losses during cooking were higher for the dehulled soybeans at both storage conditions. However, cooking requirements to achieve the same degree of texture in the cotyledons were similar for whole and dehulled seeds. Cooking time increased with prolonged storage; the effect was more noticeable in samples stored under Environment 2. Samples kept for 6 months required almost twice as much cooking than control samples. Dehulled soybeans had a lower fiber content, relatively higher amounts of protein and fat, but similar amino acid compositions than whole soybeans. Cooking caused losses of carbohydrates and ash and, therefore, significantly increased levels of protein and fat reflected by losses of solids during soaking and cooking. Among the amino acids, only cysteine suffered substantial decrease as a result of cooking. Cooking and storage inactivated 99% and from 20-35% of the trypsin inhibitors, respectively; the latter effect was more accentuated in samples stored under Environment 2. PMID:8729250

  15. Phase transition and chemical decomposition of liquid carbon dioxide and nitrogen mixture under extreme conditions

    NASA Astrophysics Data System (ADS)

    Xiao-Xu, Jiang; Guan-Yu, Chen; Yu-Tong, Li; Xin-Lu, Cheng; Cui-Ming, Tang

    2016-02-01

    Thermodynamic and chemical properties of liquid carbon dioxide and nitrogen (CO2-N2) mixture under the conditions of extremely high densities and temperatures are studied by using quantum molecular dynamic (QMD) simulations based on density functional theory including dispersion corrections (DFT-D). We present equilibrium properties of liquid mixture for 112 separate density and temperature points, by selecting densities ranging from ρ = 1.80 g/cm3 to 3.40 g/cm3 and temperatures from T = 500 K to 8000 K. In the range of our study, the liquid CO2-N2 mixture undergoes a continuous transition from molecular to atomic fluid state and liquid polymerization inferred from pair correlation functions (PCFs) and the distribution of various molecular components. The insulator-metal transition is demonstrated by means of the electronic density of states (DOS). Project supported by the National Natural Science Foundation of China (Grant Nos. 11374217, 11135012, and 11375262) and the Joint Fund of the National Natural Science Foundation of China and the China Academy of Engineering Physics (Grant No. 11176020).

  16. Extent of hydrogen coverage of Si(001) under chemical vapor deposition conditions from ab initio approaches.

    PubMed

    Rosenow, Phil; Tonner, Ralf

    2016-05-28

    The extent of hydrogen coverage of the Si(001) c(4 × 2) surface in the presence of hydrogen gas has been studied with dispersion corrected density functional theory. Electronic energy contributions are well described using a hybrid functional. The temperature dependence of the coverage in thermodynamic equilibrium was studied computing the phonon spectrum in a supercell approach. As an approximation to these demanding computations, an interpolated phonon approach was found to give comparable accuracy. The simpler ab initio thermodynamic approach is not accurate enough for the system studied, even if corrections by the Einstein model for surface vibrations are considered. The on-set of H2 desorption from the fully hydrogenated surface is predicted to occur at temperatures around 750 K. Strong changes in hydrogen coverage are found between 1000 and 1200 K in good agreement with previous reflectance anisotropy spectroscopy experiments. These findings allow a rational choice for the surface state in the computational treatment of chemical reactions under typical metal organic vapor phase epitaxy conditions on Si(001). PMID:27250324

  17. Extent of hydrogen coverage of Si(001) under chemical vapor deposition conditions from ab initio approaches

    NASA Astrophysics Data System (ADS)

    Rosenow, Phil; Tonner, Ralf

    2016-05-01

    The extent of hydrogen coverage of the Si(001) c(4 × 2) surface in the presence of hydrogen gas has been studied with dispersion corrected density functional theory. Electronic energy contributions are well described using a hybrid functional. The temperature dependence of the coverage in thermodynamic equilibrium was studied computing the phonon spectrum in a supercell approach. As an approximation to these demanding computations, an interpolated phonon approach was found to give comparable accuracy. The simpler ab initio thermodynamic approach is not accurate enough for the system studied, even if corrections by the Einstein model for surface vibrations are considered. The on-set of H2 desorption from the fully hydrogenated surface is predicted to occur at temperatures around 750 K. Strong changes in hydrogen coverage are found between 1000 and 1200 K in good agreement with previous reflectance anisotropy spectroscopy experiments. These findings allow a rational choice for the surface state in the computational treatment of chemical reactions under typical metal organic vapor phase epitaxy conditions on Si(001).

  18. [Influence of ancient glass samples surface conditions on chemical composition analysis using portable XRF].

    PubMed

    Liu, Song; Li, Qing-hui; Gan, Fu-xi

    2011-07-01

    Portable X-ray fluorescence analysis (PXRF) is one kind of surface analysis techniques, and the sample surface condition is an important factor that influences the quantitative analysis results. The ancient glass samples studied in the present paper were excavated from Xinjiang, Guangxi, Jiangsu provinces, and they belong to Na2O-CaO-SiO2, K2O-SiO2, and PbO-BaO-SiO2 system, respectively. Quantitative analysis results of weathered surface and inside of the ancient glass samples were compared. The concentration change of main fluxes in different parts of the samples was pointed out. Meanwhile, the authors studied the effect of distance between the sample and the reference plane, and curve shape of the sample on the quantitative results. The results obtained were calibrated by three methods, and the validity of these three methods was proved. Finally, the normalizing method was proved to be a better method for quantitative analysis of antiques. This paper also has guiding significance for chemical composition analysis of ancient jade samples using PXRF. PMID:21942060

  19. Influences of solution chemical conditions on mobilization of TNT from contaminated soil

    SciTech Connect

    Dante, D.A.; Tiller, C.L.; Pennell, K.D.

    1996-12-31

    Residual explosives and their byproducts are common contaminants at several US military installations. One of the major explosive contaminants is 2,4,6-Trinitrotoluene (TNT) (a hydrophobic organic compound). Contamination from TNT has resulted from manufacturing and handling processes which occurred at military installations, especially Army Ammunition Plants (AAP), over many decades until environmental regulations were implemented. TNT causes adverse effects to the environment, including growth inhibition to plants, toxicity to aquatic life, and possible mutagenicity, and also is toxic to humans. As a result of the effects of TNT on the environment and current environmental regulations, substantial research effort has been focused on determining the fate of TNT in natural systems and the development of remediation processes. Many potential remediation processes, such as those involving plants or microorganisms, are in part limited by the transfer of TNT from solid phases (e.g., sorbed to soil or present as TNT granules) to the aqueous phase. The purpose of this research is to assess the release of TNT from a soil phase to a mobile aqueous phase under varying solution chemical conditions. In particular, influences of pH, aquatic natural organic matter, and surfactants are investigated.

  20. Baseline Flowsheet Generation for the Treatment and Disposal of Idaho National Engineering and Environmental Laboratory Sodium Bearing Waste

    SciTech Connect

    Barnes, Charles Marshall; Lauerhass, Lance; Olson, Arlin Leland; Taylor, Dean Dalton; Valentine, James Henry; Lockie, Keith Andrew

    2002-02-01

    The High-Level Waste (HLW) Program at the Idaho National Engineering and Environmental Laboratory (INEEL) must implement technologies and processes to treat and qualify radioactive wastes located at the Idaho Nuclear Technology and Engineering Center (INTEC) for permanent disposal. This paper describes the approach and accomplishments to date for completing development of a baseline vitrification treatment flowsheet for sodium-bearing waste (SBW), including development of a relational database used to manage the associated process assumptions. A process baseline has been developed that includes process requirements, basis and assumptions, process flow diagrams, a process description, and a mass balance. In the absence of actual process or experimental results, mass and energy balance data for certain process steps are based on assumptions. Identification, documentation, validation, and overall management of the flowsheet assumptions are critical to ensuring an integrated, focused program. The INEEL HLW Program initially used a roadmapping methodology, developed through the INEEL Environmental Management Integration Program, to identify, document, and assess the uncertainty and risk associated with the SBW flowsheet process assumptions. However, the mass balance assumptions, process configuration and requirements should be accessible to all program participants. This need resulted in the creation of a relational database that provides formal documentation and tracking of the programmatic uncertainties related to the SBW flowsheet.

  1. Baseline Flowsheet Generation for the Treatment and Disposal of Idaho National Engineering and Environmental Laboratory Sodium Bearing Waste

    SciTech Connect

    Barnes, C.M.; Lauerhass, L.; Olson, A.L.; Taylor, D.D.; Valentine, J.H.; Lockie, K.A.

    2002-01-16

    The High-Level Waste (HLW) Program at the Idaho National Engineering and Environmental Laboratory (INEEL) must implement technologies and processes to treat and qualify radioactive wastes located at the Idaho Nuclear Technology and Engineering Center (INTEC) for permanent disposal. This paper describes the approach and accomplishments to date for completing development of a baseline vitrification treatment flowsheet for sodium-bearing waste (SBW), including development of a relational database used to manage the associated process assumptions. A process baseline has been developed that includes process requirements, basis and assumptions, process flow diagrams, a process description, and a mass balance. In the absence of actual process or experimental results, mass and energy balance data for certain process steps are based on assumptions. Identification, documentation, validation, and overall management of the flowsheet assumptions are critical to ensuring an integrated, focused program. The INEEL HLW Program initially used a roadmapping methodology, developed through the INEEL Environmental Management Integration Program, to identify, document, and assess the uncertainty and risk associated with the SBW flowsheet process assumptions. However, the mass balance assumptions, process configuration and requirements should be accessible to all program participants. This need resulted in the creation of a relational database that provides formal documentation and tracking of the programmatic uncertainties related to the SBW flowsheet.

  2. HLW flowsheet material balance for DWPF rad operation with Tank 51 sludge and ITP Cycle 1 precipitate

    SciTech Connect

    Choi, A.S.

    1995-04-19

    This document presents the details of the Savannah River Plant Flowsheet for the Rad Operation with Tank Sludge and ITP Cycle 1 Precipitate. Topics discussed include: material balance; radiolysis chemistry of tank precipitates; algorithm for ESP washing; chemistry of hydrogen and ammonia generation in CPC; batch sizes for processing feed; and total throughput of a streams during one cycle of operation.

  3. Experimental investigation and modeling of uranium (VI) transport under variable chemical conditions

    USGS Publications Warehouse

    Kohler, M.; Curtis, G.P.; Kent, D.B.; Davis, J.A.

    1996-01-01

    The transport of adsorbing and complexing metal ions in porous media was investigated with a series of batch and column experiments and with reactive solute transport modeling. Pulses of solutions containing U(VI) were pumped through columns filled with quartz grains, and the breakthrough of U(VI) was studied as a function of variable solution composition (pH, total U(VI) concentration, total fluoride concentration, and pH-buffering capacity). Decreasing p H and the formation of nonadsorbing aqueous complexes with fluoride increased U(VI) mobility. A transport simulation with surface complexation model (SCM) parameters estimated from batch experiments was able to predict U(VI) retardation in the column experiments within 30%. SCM parameters were also estimated directly from transport data, using the results of three column experiments collected at different pH and U(VI) pulse concentrations. SCM formulations of varying complexity (multiple surface types and reaction stoichiometries) were tested to examine the trade-off between model simplicity and goodness of fit to breakthrough. A two-site model (weak- and strong-binding sites) with three surface complexation reactions fit these transport data well. With this reaction set the model was able to predict (1) the effects of fluoride complexation on U(VI) retardation at two different pH values and (2) the effects of temporal variability of pH on U(VI) transport caused by low p H buffering. The results illustrate the utility of the SCM approach in modeling the transport of adsorbing inorganic solutes under variable chemical conditions.

  4. Conditional Toxicity Value (CTV) Predictor for Generating Toxicity Values for Data Sparse Chemicals (Poster)

    EPA Science Inventory

    Various stakeholders and expert groups, including the National Research Council in Science and Decisions, call for “default approaches to support risk estimation for chemicals lacking chemical-specific information.” This project aims to address this challenge through ...

  5. Massive star evolution in close binaries. Conditions for homogeneous chemical evolution

    NASA Astrophysics Data System (ADS)

    Song, H. F.; Meynet, G.; Maeder, A.; Ekström, S.; Eggenberger, P.

    2016-01-01

    Aims: We investigate the impact of tidal interactions, before any mass transfer, on various properties of the stellar models. We study the conditions for obtaining homogeneous evolution triggered by tidal interactions, and for avoiding any Roche lobe overflow (RLOF) during the main-sequence phase. By homogeneous evolution, we mean stars evolving with a nearly uniform chemical composition from the centre to the surface. Methods: We consider the case of rotating stars computed with a strong core-envelope coupling mediated by an interior magnetic field. Models with initial masses between 15 and 60 M⊙, for metallicities between 0.002 and 0.014 and with initial rotation equal to 30% and 66% the critical rotation on the zero age main sequence, are computed for single stars and for stars in close binary systems. We consider close binary systems with initial orbital periods equal to 1.4, 1.6, and 1.8 days and a mass ratio equal to 3/2. Results: In models without any tidal interaction (single stars and wide binaries), homogeneous evolution in solid body rotating models is obtained when two conditions are realised: the initial rotation must be high enough, and the loss of angular momentum by stellar winds should be modest. This last point favours metal-poor fast rotating stars. In models with tidal interactions, homogeneous evolution is obtained when rotation imposed by synchronisation is high enough (typically a time-averaged surface velocities during the main-sequence phase above 250 km s-1), whatever the mass losses. We present plots that indicate for which masses of the primary and for which initial periods the conditions for the homogenous evolution and avoidance of the RLOF are met, for various initial metallicities and rotations. In close binaries, mixing is stronger at higher than at lower metallicities. Homogeneous evolution is thus favoured at higher metallicities. RLOF avoidance is favoured at lower metallicities because stars with less metals remain more

  6. The Effect of Cooperative Learning Approach Based on Conceptual Change Condition on Students' Understanding of Chemical Equilibrium Concepts

    ERIC Educational Resources Information Center

    Bilgin, Ibrahim; Geban, Omer

    2006-01-01

    The purpose of this study is to investigate the effects of the cooperative learning approach based on conceptual change conditions over traditional instruction on 10th grade students' conceptual understanding and achievement of computational problems related to chemical equilibrium concepts. The subjects of this study consisted of 87 tenth grade…

  7. Transport and Fate of Bacteria in Porous Media: Coupled Effects of Chemical Conditions and Pore Space Geometry

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Experimental and theoretical studies were undertaken to explore the coupling effects of chemical conditions and pore space geometry on bacteria transport in porous media. The retention of Escherichia coli D21g was investigated in a series of batch and column experiments with solutions of different i...

  8. Hanford Low-Activity Waste Processing: Demonstration of the Off-Gas Recycle Flowsheet - 13443

    SciTech Connect

    Ramsey, William G.; Esparza, Brian P.

    2013-07-01

    Vitrification of Hanford Low-Activity Waste (LAW) is nominally the thermal conversion and incorporation of sodium salts and radionuclides into borosilicate glass. One key radionuclide present in LAW is technetium-99. Technetium-99 is a low energy, long-lived beta emitting radionuclide present in the waste feed in concentrations on the order of 1-10 ppm. The long half-life combined with a high solubility in groundwater results in technetium-99 having considerable impact on performance modeling (as potential release to the environment) of both the waste glass and associated secondary waste products. The current Hanford Tank Waste Treatment and Immobilization Plant (WTP) process flowsheet calls for the recycle of vitrification process off-gas condensates to maximize the portion of technetium ultimately immobilized in the waste glass. This is required as technetium acts as a semi-volatile specie, i.e. considerable loss of the radionuclide to the process off-gas stream can occur during the vitrification process. To test the process flowsheet assumptions, a prototypic off-gas system with recycle capability was added to a laboratory melter (on the order of 1/200 scale) and testing performed. Key test goals included determination of the process mass balance for technetium, a non-radioactive surrogate (rhenium), and other soluble species (sulfate, halides, etc.) which are concentrated by recycling off-gas condensates. The studies performed are the initial demonstrations of process recycle for this type of liquid-fed melter system. This paper describes the process recycle system, the waste feeds processed, and experimental results. Comparisons between data gathered using process recycle and previous single pass melter testing as well as mathematical modeling simulations are also provided. (authors)

  9. Metabolic profiling of Lolium perenne shows functional integration of metabolic responses to diverse subtoxic conditions of chemical stress.

    PubMed

    Serra, Anne-Antonella; Couée, Ivan; Renault, David; Gouesbet, Gwenola; Sulmon, Cécile

    2015-04-01

    Plant communities are confronted with a great variety of environmental chemical stresses. Characterization of chemical stress in higher plants has often been focused on single or closely related stressors under acute exposure, or restricted to a selective number of molecular targets. In order to understand plant functioning under chemical stress conditions close to environmental pollution conditions, the C3 grass Lolium perenne was subjected to a panel of different chemical stressors (pesticide, pesticide degradation compound, polycyclic aromatic hydrocarbon, and heavy metal) under conditions of seed-level or root-level subtoxic exposure. Physiological and metabolic profiling analysis on roots and shoots revealed that all of these subtoxic chemical stresses resulted in discrete physiological perturbations and complex metabolic shifts. These metabolic shifts involved stressor-specific effects, indicating multilevel mechanisms of action, such as the effects of glyphosate and its degradation product aminomethylphosphonic acid on quinate levels. They also involved major generic effects that linked all of the subtoxic chemical stresses with major modifications of nitrogen metabolism, especially affecting asparagine, and of photorespiration, especially affecting alanine and glycerate. Stress-related physiological effects and metabolic adjustments were shown to be integrated through a complex network of metabolic correlations converging on Asn, Leu, Ser, and glucose-6-phosphate, which could potentially be modulated by differential dynamics and interconversion of soluble sugars (sucrose, trehalose, fructose, and glucose). Underlying metabolic, regulatory, and signalling mechanisms linking these subtoxic chemical stresses with a generic impact on nitrogen metabolism and photorespiration are discussed in relation to carbohydrate and low-energy sensing. PMID:25618145

  10. Metabolic profiling of Lolium perenne shows functional integration of metabolic responses to diverse subtoxic conditions of chemical stress

    PubMed Central

    Serra, Anne-Antonella; Couée, Ivan; Renault, David; Gouesbet, Gwenola; Sulmon, Cécile

    2015-01-01

    Plant communities are confronted with a great variety of environmental chemical stresses. Characterization of chemical stress in higher plants has often been focused on single or closely related stressors under acute exposure, or restricted to a selective number of molecular targets. In order to understand plant functioning under chemical stress conditions close to environmental pollution conditions, the C3 grass Lolium perenne was subjected to a panel of different chemical stressors (pesticide, pesticide degradation compound, polycyclic aromatic hydrocarbon, and heavy metal) under conditions of seed-level or root-level subtoxic exposure. Physiological and metabolic profiling analysis on roots and shoots revealed that all of these subtoxic chemical stresses resulted in discrete physiological perturbations and complex metabolic shifts. These metabolic shifts involved stressor-specific effects, indicating multilevel mechanisms of action, such as the effects of glyphosate and its degradation product aminomethylphosphonic acid on quinate levels. They also involved major generic effects that linked all of the subtoxic chemical stresses with major modifications of nitrogen metabolism, especially affecting asparagine, and of photorespiration, especially affecting alanine and glycerate. Stress-related physiological effects and metabolic adjustments were shown to be integrated through a complex network of metabolic correlations converging on Asn, Leu, Ser, and glucose-6-phosphate, which could potentially be modulated by differential dynamics and interconversion of soluble sugars (sucrose, trehalose, fructose, and glucose). Underlying metabolic, regulatory, and signalling mechanisms linking these subtoxic chemical stresses with a generic impact on nitrogen metabolism and photorespiration are discussed in relation to carbohydrate and low-energy sensing. PMID:25618145

  11. Li ceramic pebbles chemical compatibility with Eurofer samples in fusion relevant conditions

    NASA Astrophysics Data System (ADS)

    Alves, L. C.; Alves, E.; da Silva, M. R.; Paúl, A.; La Barbera, A.

    2004-08-01

    Information on the chemical compatibility between Li ceramic breeders and reactor structural materials is an important issue for fusion reactor technology. In this work, Eurofer samples were placed inside a Li ceramic pebble bed and kept at 600 °C under a reducing atmosphere obtained by the flow of a purging gas (He + 0.1vol.%H 2). Titanate and orthosilicate Li pebble beds were used in the experiments and exposure time ranged from 50 to 2000 h. Surface chemical reactions were investigated with nuclear microprobe techniques. The orthosilicate pebbles present chemical reactions even with the gas mixture, whereas for the samples in close contact with Eurofer there is evidence of Eurofer elemental diffusion into the pebbles and the formation of different types of compounds. Although the titanate pebbles used in the chemical compatibility experiments present surface alterations with increasing surface irregularities along the annealing time, there is no clear indication of Eurofer constituents diffusion.

  12. Modeling the transport of organic chemicals between polyethylene passive samplers and water in finite and infinite bath conditions.

    PubMed

    Tcaciuc, A Patricia; Apell, Jennifer N; Gschwend, Philip M

    2015-12-01

    Understanding the transfer of chemicals between passive samplers and water is essential for their use as monitoring devices of organic contaminants in surface waters. By applying Fick's second law to diffusion through the polymer and an aqueous boundary layer, the authors derived a mathematical model for the uptake of chemicals into a passive sampler from water, in finite and infinite bath conditions. The finite bath model performed well when applied to laboratory observations of sorption into polyethylene (PE) sheets for various chemicals (polycyclic aromatic hydrocarbons, polychlorinated biphenyls [PCBs], and dichlorodiphenyltrichloroethane [DDT]) and at varying turbulence levels. The authors used the infinite bath model to infer fractional equilibration of PCB and DDT analytes in field-deployed PE, and the results were nearly identical to those obtained using the sampling rate model. However, further comparison of the model and the sampling rate model revealed that the exchange of chemicals was inconsistent with the sampling rate model for partially or fully membrane-controlled transfer, which would be expected in turbulent conditions or when targeting compounds with small polymer diffusivities and small partition coefficients (e.g., phenols, some pesticides, and others). The model can be applied to other polymers besides PE as well as other chemicals and in any transfer regime (membrane, mixed, or water boundary layer-controlled). Lastly, the authors illustrate practical applications of this model such as improving passive sampler design and understanding the kinetics of passive dosing experiments. PMID:26109238

  13. Maximizing productivity of CHO cell-based fed-batch culture using chemically defined media conditions and typical manufacturing equipment.

    PubMed

    Huang, Yao-Ming; Hu, WeiWei; Rustandi, Eddie; Chang, Kevin; Yusuf-Makagiansar, Helena; Ryll, Thomas

    2010-01-01

    A highly productive chemically defined fed-batch process was developed to maximize titer and volumetric productivity for Chinese hamster ovary cell-based recombinant protein manufacturing. Two cell lines producing a recombinant antibody (cell line A) and an Fc-fusion protein (cell line B) were used for development. Both processes achieved product titers of 10 g/L on day 18 under chemically defined conditions. For cell line B, the use of plant derived hydrolysates combined with the optimized chemically defined medium increased the titer to 13 g/L. Volumetric productivities were increased from a base line of about 200 mg/L/d to about 500 mg/L/d under chemically defined conditions and as high as 700 mg/L/d with cell line B using plant derived hydrolysates. Peak cell densities reached greater than 20E6 vc/mL, and cell viabilities were maintained above 80% on day 18 without the use of antiapoptotic genes or temperature shift. A rapid compound screening method was developed to effectively test positive factors within 72 h. Peak volumetric oxygen uptake rates (OUR) more than tripled from the baseline condition. Oxygen demand continued to increase after maximum cell density was reached with a maximal OUR of 3.7 mmol/L/h. The new process format was scaled up and verified at 100 L pilot scale using reactor equipment of similar configuration as used at manufacturing scale. PMID:20945494

  14. Laboratory conditions and safety in a chemical warfare agent analysis and research laboratory.

    PubMed

    Kenar, Levent; Karayilanoğlu, Turan; Kose, Songul

    2002-08-01

    Toxic chemicals have been used as weapons of war and also as means of terrorist attacks on civilian populations. Research focusing on chemical warfare agents (CWAs) may be associated with an increased risk of exposure to and contamination by these agents. This article summarizes some of the regulations concerning designation and safety in a CWA analysis and research laboratory and medical countermeasures in case of an accidental exposure. The design of such a laboratory, coupled with a set of safety guidelines, provides for the safe conduct of research and studies involving CWAs. Thus, a discussion of decontamination and protection means against CWAs is also presented. PMID:12188231

  15. Clinical vocabulary as a boundary object in multidisciplinary care management of multiple chemical sensitivity, a complex and chronic condition

    PubMed Central

    Sampalli, Tara; Shepherd, Michael; Duffy, Jack

    2011-01-01

    Background: Research has shown that accurate and timely communication between multidisciplinary clinicians involved in the care of complex and chronic health conditions is often challenging. The domain knowledge for these conditions is heterogeneous, with poorly categorized, unstructured, and inconsistent clinical vocabulary. The potential of boundary object as a technique to bridge communication gaps is explored in this study. Methods: A standardized and controlled clinical vocabulary was developed as a boundary object in the domain of a complex and chronic health condition, namely, multiple chemical sensitivity, to improve communication among multidisciplinary clinicians. A convenience sample of 100 patients with a diagnosis of multiple chemical sensitivity, nine multidisciplinary clinicians involved in the care of patients with multiple chemical sensitivity, and 36 clinicians in the community participated in the study. Results: Eighty-two percent of the multidisciplinary and inconsistent vocabulary was standardized using the Systematized Nomenclature of Medicine – Clinical Terms (SNOMED® CT as a reference terminology. Over 80% of the multidisciplinary clinicians agreed on the overall usefulness of having a controlled vocabulary as a boundary object. Over 65% of clinicians in the community agreed on the overall usefulness of the vocabulary. Conclusion: The results from this study are promising and will be further evaluated in the domain of another complex chronic condition, ie, chronic pain. The study was conducted as a preliminary analysis for developing a boundary object in a heterogeneous domain of knowledge. PMID:21594060

  16. Numerical simulation of the middle atmosphere chemical composition and temperature under changing solar conditions

    NASA Technical Reports Server (NTRS)

    Zadorozhny, A. M.; Dyominov, I. G.; Tuchkov, G. A.

    1989-01-01

    There are given results of the numerical experiments on modelling the influence of solar activity on chemical composition and temperature of the middle atmosphere. The consideration is made for peculiarities of solar activity impact under different values of antropogenic pollution of the atmosphere with chlorofluorocarbons and other stuff.

  17. Influence of coal briquetting conditions on the chemical composition of the products of thermal degradation

    SciTech Connect

    Turenko, F.P.

    1984-01-01

    A spectro-statistical method was used to examine the chemical composition of liquid non-volatile constituents from a mixture of Donbass coals (gas, fat, lean, caking). The thermal destruction products obtained by thermal filtration in a centrifugal field from both briquetted and non-briquetted charges differ in terms of their structural group content.

  18. THE INSTABILITY OF ESTROGENIC CHEMICALS DURING LABORATORY STATIC EXPOSURE CONDITIONS WITH MALE FATHEAD MINNOWS

    EPA Science Inventory

    Endocrine disrupting chemicals (EDCs) such as Para-nonylphenol (NP), estradiol (E2), estrone (E1), estriol (E3) and ethynylestradiol (EE2) are shown to be ubiquitous in surface waters, sediments and sludge. These EDCs are known to induce vitellogenin gene (Vg) expression in male...

  19. Low-thrust chemical propulsion system propellant expulsion and thermal conditioning study. Executive summary

    NASA Technical Reports Server (NTRS)

    Merino, F.; Wakabayashi, I.; Pleasant, R. L.; Hill, M.

    1982-01-01

    Preferred techniques for providing abort pressurization and engine feed system net positive suction pressure (NPSP) for low thrust chemical propulsion systems (LTPS) were determined. A representative LTPS vehicle configuration is presented. Analysis tasks include: propellant heating analysis; pressurant requirements for abort propellant dump; and comparative analysis of pressurization techniques and thermal subcoolers.

  20. Chemical sludge conditioning in combination with different conventional and alternative dewatering devices: chamber filter press, decanter and Bucher press.

    PubMed

    Schaum, Christian; Cornel, Peter; Faria, Pedro; Recktenwald, Michael; Norrlöw, Olof

    2008-11-01

    The Kemicond process for sludge conditioning consists of chemical treatment with sulphuric acid and hydrogen peroxide at a pH-value of approximately 4 followed by a dewatering unit. It is shown that chemical treatment can improve the dewaterability of ferruginous digested sludge. It is concluded that the Fenton process as well as the oxidation of organics and the formation of iron hydroxo complexes are important reaction mechanisms. Furthermore, the organic matter changes through the acidic oxidative process. With the improvement in dewaterability, it is possible to achieve an increase in TS concentration, which affects a reduction of the sludge volume. Cost savings for sludge disposal can amortize the additional investment and operational costs for chemical treatment. PMID:18821238

  1. Preliminary flowsheet: Ion exchange process for the separation of cesium from Hanford tank waste using Duolite{trademark} CS-100 resin

    SciTech Connect

    Eager, K.M.; Penwell, D.L.; Knutson, B.J.

    1994-12-01

    This preliminary flowsheet document describes an ion exchange process which uses Duolite{trademark} CS-100 resin to remove cesium from Hanford Tank waste. The flowsheet describes one possible equipment configuration, and contains mass balances based on that configuration with feeds of Neutralized Current Acid Waste, and Double Shell Slurry Feed. Process alternatives, unresolved issues, and development needs are discussed which relate to the process.

  2. Evaluation of the Submerged Demineralizer System (SDS) flowsheet for decontamination of high-activity-level water at the Three Mile Island Unit 2 Nuclear Power Station

    SciTech Connect

    Campbell, D. O.; Collins, E. D.; King, L. J.; Knauer, J. B.

    1980-07-01

    This report discusses the Submerged Demineralizer System (SDS) flowsheet for decontamination of the high-activity-level water at the Three Mile Island Unit 2 Nuclear Power Station was evaluated at Oak Ridge National Laboratory in a study that included filtration tests, ion exchange column tests, and ion exchange distribution tests. The contaminated waters, the SDS flowsheet, and the experiments made are described. The experimental results were used to predict the SDS performance and to indicate potential improvements.

  3. “Reading Between the Lines” of Flowsheet Data: Nurses' Optional Documentation Associated with Cardiac Arrest Outcomes

    PubMed Central

    Collins, Sarah A.; Vawdrey, David K.

    2011-01-01

    Historically, short ‘comments’ on paper-based flowsheets conveyed the patient's overall clinical state. We analyzed the content and documentation patterns of electronic health record flowsheets for 201 cardiac arrest patients. Free-text comments were associated with the abnormality of clinical measurements (p<0.05). The documentation of 3 or more comments for acute care patients was associated with a greater likelihood of dying by discharge (p<0.01). Documentation of ICU vital signs greater than the minimum hourly requirement was associated with increased survival of a cardiac arrest (p<0.05). Further analysis of such patterns may be useful for the measurement of nursing knowledge and surveillance activities, interdisciplinary communication tools, and clinical decision making. PMID:22079746

  4. Boundary conditions for the paleoenvironment: Chemical and Physical Processes in dense interstellar clouds

    NASA Technical Reports Server (NTRS)

    Irvine, W. M.; Schloerb, F. P.; Ziurys, L. M.

    1986-01-01

    The present research includes searches for important new interstellar constituents; observations relevant to differentiating between different models for the chemical processes that are important in the interstellar environment; and coordinated studies of the chemistry, physics, and dynamics of molecular clouds which are the sites or possible future sites of star formation. Recent research has included the detection and study of four new interstellar molecules; searches which have placed upper limits on the abundance of several other potential constituents of interstellar clouds; quantitative studies of comparative molecular abundances in different types of interstellar clouds; investigation of reaction pathways for astrochemistry from a comparison of theory and the observed abundance of related species such as isomers and isotopic variants; studies of possible tracers of energenic events related to star formation, including silicon and sulfur containing molecules; and mapping of physical, chemical, and dynamical properties over extended regions of nearby cold molecular clouds.

  5. Conditions of early chemical processing of matter - Explosive exhalations of supernovae

    NASA Technical Reports Server (NTRS)

    Heymann, D.

    1983-01-01

    The chemical and isotopic stratifications of supernova exhalations are discussed, with reference to a number of theoretical estimates. Particular attention is given to the theoretical models of the major chemical zones of explosive exhalation of isotopes of Mg, Si, and Ti in intermediate size supernovae. The contribution of supernova exhalations to oxygen anomalies in the solar system is also discussed within the framework of the theoretical models of Clayton et al. (1977, 1978, 1979, 1981). The initial stratigraphy of the major elements in the explosive exhalation of a progenitor star of 25 solar mass is illustrated in a graph, on the basis of the theoretical estimates of Waver et al. (1978), and Weaver and Woolsey (1980).

  6. Sensitivity of the invasive bivalve Corbicula fluminea to candidate control chemicals: The role of dissolved oxygen conditions.

    PubMed

    Rosa, Inês C; Garrido, Rita; Ré, Ana; Gomes, João; Pereira, Joana L; Gonçalves, Fernando; Costa, Raquel

    2015-12-01

    The freshwater Corbicula fluminea is a major aquatic nuisance worldwide. Current pest control methods raise cost-effectiveness and environmental concerns, which motivate research into improved mitigation approaches. In this context, the susceptibility of the clams to chemicals under reduced oxygen conditions was examined. Biocides with different mechanisms of toxicity (niclosamide, polyDADMAC, ammonium nitrate, potassium chloride and dimethoate) were tested under normoxic (>7 mg L(-1) dissolved O2) and hypoxic (<2 mg L(-1) dissolved O2) conditions. Hypoxia was observed to potentiate chemical treatment, particularly when combined with non-overwhelming doses that would produce only intermediate responses by themselves. For niclosamide, ammonium nitrate and dimethoate, clam mortality enhancements up to 400% were observed under hypoxia as compared to dosing upon normal dissolved oxygen conditions. For polyDADMAC and potassium chloride, substantially lower mortality enhancements were found. The differences in the clams' sensitivity to the chemicals under hypoxia could be linked to the expected mechanisms of action. This suggests that judicious selection of the biocide is essential if optimized combined control treatments are to be designed and provides an insight into the interference of frequent hypoxia events in the response of natural clam populations to contaminant loads. PMID:26254082

  7. EVALUATION OF FLOWSHEET CHANGES FOR THE HIGHLY ENRICHED URANIUM BLENDDOWN PROGRAM

    SciTech Connect

    Crowder, M.; Rudisill, T.; Laurinat, J.; Mickalonis, J.

    2007-10-22

    H Canyon is considering a flowsheet change for Plutonium (Pu) Contaminated Scrap (PuCS) material. The proposed change is to route dissolved PuCS material directly to a uranium (U) storage tank. As a result, the PuCS solution will bypass Head End and First U Cycle, and will be purified by solvent extraction in Second U Cycle. The PuCS solution contains appreciable amounts of boron (B) and fluoride (F{sup -}), which are currently at trace levels in the U storage tank. Though unlikely, if the B concentration in the U storage tank were to reach 1.8 g B/g U, the entire contents of the U storage tank would likely require a second pass through Second U Cycle to provide sufficient decontamination to meet the Tennessee Valley Authority (TVA) Blend Grade Highly Enriched Uranium (HEU) specification for B, which is 30 {micro}g/g U. In addition, Second U Cycle is expected to provide sufficient decontamination of F{sup -} and Pu regardless of the amount of PuCS solution sent to the storage tank. Though aluminum (Al) is not present in the PuCS solution, B can be credited as a complexant of F{sup -}. Both stability constants from the literature and Savannah River National Laboratory (SRNL) corrosion studies were documented to demonstrate that B complexation of F{sup -} in nitric acid solutions is sufficient to prevent excessive corrosion. Though B and Al complex F{sup -} to a similar degree, neither completely eliminates the presence of free F{sup -} in solution. Therefore, a limited amount of corrosion is expected even with complexed F{sup -} solutions. Tanks maintained at ambient temperature are not expected to experience significant corrosion. However, the Low Activity Waste (LAW) evaporators may be subjected to a corrosion rate of about 25 mils per year (mpy) as they reach their highest F{sup -} concentrations. The feed adjustment evaporator would only be subjected to the corrosion rate of about 25 mpy in the latter stages of the PuCS campaign. An issue that must be addressed

  8. Chemical conversion of cisplatin and carboplatin with histidine in a model protein crystallized under sodium iodide conditions

    SciTech Connect

    Tanley, Simon W. M.; Helliwell, John R.

    2014-08-29

    Crystals of HEWL with cisplatin and HEWL with carboplatin grown in sodium iodide conditions both show a partial chemical transformation of cisplatin or carboplatin to a transiodoplatin (PtI{sub 2}X{sub 2}) form. The binding is only at the N{sup δ} atom of His15. A further Pt species (PtI{sub 3}X) is also seen, in both cases bound in a crevice between symmetry-related protein molecules. Cisplatin and carboplatin are platinum anticancer agents that are used to treat a variety of cancers. Previous X-ray crystallographic studies of carboplatin binding to histidine in hen egg-white lysozyme (HEWL) showed a partial chemical conversion of carboplatin to cisplatin owing to the high sodium chloride concentration used in the crystallization conditions. Also, the co-crystallization of HEWL with carboplatin in sodium bromide conditions resulted in the partial conversion of carboplatin to the transbromoplatin form, with a portion of the cyclobutanedicarboxylate (CBDC) moiety still present. The results of the co-crystallization of HEWL with cisplatin or carboplatin in sodium iodide conditions are now reported in order to determine whether the cisplatin and carboplatin converted to the iodo form, and whether this took place in a similar way to the partial conversion of carboplatin to cisplatin in NaCl conditions or to transbromoplatin in NaBr conditions as seen previously. It is reported here that a partial chemical transformation has taken place to a transplatin form for both ligands. The NaI-grown crystals belonged to the monoclinic space group P2{sub 1} with two molecules in the asymmetric unit. The chemically transformed cisplatin and carboplatin bind to both His15 residues, i.e. in each asymmetric unit. The binding is only at the N{sup δ} atom of His15. A third platinum species is also seen in both conditions bound in a crevice between symmetry-related molecules. Here, the platinum is bound to three I atoms identified based on their anomalous difference electron densities

  9. Chemical and Isotopic Study of Lab-formed Carbonates Under Cryogenic and Hydrothermal Conditions

    NASA Technical Reports Server (NTRS)

    Niles, P. B.; Leshin, L. A.; Socki, R. A.; Guan, Y.; Golden, D. C.; Ming, D. W.; Gibson, E. K.

    2004-01-01

    Aqueous environments on early Mars were probably relatively short-lived and localized, as evidenced by the lack of abundant secondary minerals detected by the TES instrument. In order to better understand the aqueous history of early Mars we need to be able to interpret the evidence preserved in secondary minerals formed during these aqueous events. Carbonate minerals, in particular, are important secondary minerals for interpreting past aqueous environments as illustrated by the carbonates preserved in ALH84001. Carbonates formed in short-lived, dynamic aqueous events often preserve kinetic rather than equilibrium chemical and isotopic processes, and predicting the behavior of such systems is facilitated by empirical data.

  10. The effect of chemical composition and austenite conditioning on the transformation behavior of microalloyed steels

    SciTech Connect

    Mousavi Anijdan, S.H.; Rezaeian, Ahmad; Yue, Steve

    2012-01-15

    In this investigation, by using continuous cooling torsion (CCT) testing, the transformation behavior of four microalloyed steels under two circumstances of austenite conditioning and non-conditioning was studied. A full scale hot-rolling schedule containing a 13-pass deformation was employed for the conditioning of the austenite. The CCT tests were then employed till temperature of {approx} 540 Degree-Sign C and the flow curves obtained from this process were analyzed. The initial and final microstructures of the steels were studied by optical and electron microscopes. Results show that alloying elements would decrease the transformation temperature. This effect intensifies with the gradual increase of Mo, Nb and Cu as alloying elements added to the microalloyed steels. As well, austenite conditioning increased the transformation start temperature due mainly to the promotion of polygonal ferrite formation that resulted from a pancaked austenite. The final microstructures also show that CCT alone would decrease the amount of bainite by inducing ferrite transformation in the two phase region. In addition, after the transformation begins, the deformation might result in the occurrence of dynamic recrystallization in the ferrite region. This could lead to two different ferrite grain sizes at the end of the CCT. Moreover, the Nb bearing steels show no sign of decreasing the strength level after the transformation begins in the non-conditioned situation and their microstructure is a mix of polygonal ferrite and bainite indicating an absence of probable dynamic recrystallization in this condition. In the conditioned cases, however, these steels show a rapid decrease of the strength level and their final microstructures insinuate that ferrite could have undergone a dynamic recrystallization due to deformation. Consequently, no bainite was seen in the austenite conditioned Nb bearing steels. The pancaking of austenite in the latest cases produced fully polygonal ferrite

  11. An analysis of alternative New Technical Strategy flowsheets for tank waste remediation system

    SciTech Connect

    Booker, C.P.

    1994-06-01

    The Hanford Tank remediation plans have gone through a few revisions for the best waste processing system. Some designs have been complex while others have been fairly simple. One of the key means in understanding and selecting among the various proposed systems is a discrete events modeling of the system. This modeling provides insight into (1) The total required size of the system; (2) The amount of material, such as reagents and other added materials that must be supplied; (3) The final mass of waste that must be stored; and (4) Areas within the system where a small change can greatly effect the total system. Discrete events modeling also provides the means by which various proposed systems may be compared. It is the framework in which variations within a particular system may be explored and compared to other instantiations. This study examines the current New Technical Strategy flowsheet system with discrete event modeling. Some of the possible variations within that system are examined and compared. Further, an previously proposed, more complex system is examined.

  12. Status of development of actinide blanket processing flowsheets for accelerator transmutation of nuclear waste

    SciTech Connect

    Dewey, H.J.; Jarvinen, G.D.; Marsh, S.F.; Schroeder, N.C.; Smith, B.F.; Villarreal, R.; Walker, R.B.; Yarbro, S.L.; Yates, M.A.

    1993-09-01

    An accelerator-driven subcritical nuclear system is briefly described that transmutes actinides and selected long-lived fission products. An application of this accelerator transmutation of nuclear waste (ATW) concept to spent fuel from a commercial nuclear power plant is presented as an example. The emphasis here is on a possible aqueous processing flowsheet to separate the actinides and selected long-lived fission products from the remaining fission products within the transmutation system. In the proposed system the actinides circulate through the thermal neutron flux as a slurry of oxide particles in heavy water in two loops with different average residence times: one loop for neptunium and plutonium and one for americium and curium. Material from the Np/Pu loop is processed with a short cooling time (5-10 days) because of the need to keep the total actinide inventory, low for this particular ATW application. The high radiation and thermal load from the irradiated material places severe constraints on the separation processes that can be used. The oxide particles are dissolved in nitric acid and a quarternary, ammonium anion exchanger is used to extract neptunium, plutonium, technetium, and palladium. After further cooling (about 90 days), the Am, Cm and higher actinides are extracted using a TALSPEAK-type process. The proposed operations were chosen because they have been successfully tested for processing high-level radioactive fuels or wastes in gram to kilogram quantities.

  13. Guidelines for measuring the physical, chemical, and biological condition of wilderness ecosystems. General technical report (Final)

    SciTech Connect

    Fox, D.G.; Bernabo, J.C.; Hood, B.

    1987-11-01

    Guidelines include a large number of specific measures to characterize the existing condition of wilderness resources. Measures involve the atmospheric environment, water chemistry and biology, geology and soils, and flora. Where possible, measures are coordinated with existing long-term monitoring programs. Application of the measures will allow more effective evaluation of proposed new air-pollution sources.

  14. Chemically defined conditions for human iPS cell derivation and culture

    PubMed Central

    Chen, Guokai; Gulbranson, Daniel R.; Hou, Zhonggang; Bolin, Jennifer M.; Ruotti, Victor; Probasco, Mitchell D.; Smuga-Otto, Kimberly; Howden, Sara E.; Diol, Nicole R.; Propson, Nicholas E.; Wagner, Ryan; Lee, Garrett O.; Antosiewicz-Bourget, Jessica; Teng, Joyce M. C.; Thomson, James A.

    2011-01-01

    We reexamine the individual components for human ES and iPS cell culture, and formulate a cell culture system in which all protein reagents for liquid media, attachment surfaces, and splitting are chemically defined. A major improvement is the lack of a serum albumin component, as variations in either animal or human sourced albumin batches have previously plagued human ES and iPS cell culture with inconsistencies. Using this new medium (E8) and vitronectin-coated surfaces, we demonstrate improved derivation efficiencies of vector-free human iPS cells with an episomal approach. This simplified E8 medium should facilitate both the research use and clinical applications of human ES and iPS cells and their derivatives, and should be applicable to other reprogramming methods. PMID:21478862

  15. Solving Heat Conduction Problems in Movable Boundary Domains under Intensive Physical-Chemical Transformation Conditions

    NASA Astrophysics Data System (ADS)

    Garashchenko, A. N.; Rudzinsky, V. P.; Garashchenko, N. A.

    2016-02-01

    Results of solving problems of simulating temperature fields in domains with movable boundaries of characteristic zones of intensive physical-chemical and thermomechanical transformations to be realized in materials upon high-temperature heating have been presented. Intumescent fire-protective coatings based on organic and mineral materials are the object of study. Features of numerical realization of input equation systems taking into account, in particular, a dynamics of considerable increase and subsequent decrease of the intumescent layer thickness have been considered. Example calculations for structures of metal and wood protected with various coatings are given. Results of calculating two-dimensional temperature fields in polymer composite square-shaped structures with internal cruciform load-bearing elements have been presented. The intumescent coating is arranged on the external surface of a structure. The solution of the above-listed problems is of important significance to provide fire protection of different-purpose structures and products.

  16. Effect of preparation conditions on physic-chemical properties of tin-doped nanocrystalline indium oxide

    NASA Astrophysics Data System (ADS)

    Malinovskaya, T. D.; Sachkov, V. I.; Zhek, V. V.; Nefedov, R. A.

    2016-01-01

    In this paper the results of investigation of phase formation and change of concentration of free electrons (Ne) in indium tin oxide system during heat treatment of coprecipitated hydroxides of indium and tin from nitric and hydrochloric solutions and also, for comparison melts of salts nitrates by an alkaline reactant (NH4OH) are considered.The performed investigation allowed to set the optimal condition of preparation of polycrystalline tin-doped indium oxide with maximal electron concentration.

  17. Evaluation of the migration of chemicals from baby bottles under standardised and duration testing conditions.

    PubMed

    Onghena, Matthias; Van Hoeck, Els; Negreira, Noelia; Quirynen, Laurent; Van Loco, Joris; Covaci, Adrian

    2016-05-01

    After the prohibition of bisphenol-A-containing polycarbonate baby bottles in the European Union (EU), alternative materials, such as polypropylene, polyethersulphone, Tritan™ copolyester, etc., have appeared on the market. Based on an initial screening and in vitro toxicity assessment, the most toxic migrating compounds were selected to be monitored and quantified using validated GC- and LC-QqQ-MS methods. The effect of several 'real-life-use conditions', such as microwave, sterilisation and dishwasher, on the migration of different contaminants was evaluated by means of duration tests. These results were compared with a reference treatment (filling five times with pre-heated simulant at 40°C) and with the legal EU 'repetitive-use conditions' (three migrations, 2 h at 70°C). Analysis of the third migration step of the EU repetitive-use conditions (which has to comply with the EU legislative migration limits) showed that several non-authorised compounds were observed in some baby bottles exceeding 10 µg kg(-1). However, all authorised compounds were detected well below their respective specific migration limits (SMLs). The reference experiment confirmed the migration of some of the compounds previously detected in the EU repetitive-use experiment, though at lower concentrations. Analysis of extracts from the microwave and dishwasher experiments showed a reduction in the migration during the duration tests. In general, the concentrations found were low and comparable with the reference experiment. Similar observations were made for the two sterilisation types: steam and cooking sterilisation. However, steam sterilisation seems to be more recommended for daily use of baby bottles, since it resulted in a lower release of substances afterwards. Repeated use of baby bottles under 'real-life' conditions showed no increase in the migration of investigated compounds and, after some time, the migration of these compounds even became negligible. PMID:27043734

  18. Field lysimeters for the study of fate and transport of explosive chemicals in soils under variable environmental conditions

    NASA Astrophysics Data System (ADS)

    Molina, Gloria M.; Padilla, Ingrid; Pando, Miguel; Pérez, Diego D.

    2006-05-01

    Landmines and other buried explosive devices pose in an immense threat in many places of the world, requiring large efforts on detection and neutralization of these objects. Many of the available detection techniques require the presence of chemicals near the soil-atmospheric surface. The presence of explosive related chemicals (ERCs) near this surface and their relation to the location of landmines, however, depends on the source characteristics and on fate and transport processes that affect their movement in soils. Fate and transport processes of ERC is soils may be interrelated with each other and are influenced by chemical characteristics and interrelated soil and environmental factors. Accurate detection of ERCs near the soil surface must, therefore, take into the variability of ERC concentration distributions near the soil surface as affected by fate and transport processes controlled interrelated environmental factors. To effectively predict the concentration distributions of ERCs in soils and near soil surfaces, it is necessary to have good understanding of parameters values that control these processes. To address this need, field lysimeters have been designed and developed at the University of Puerto Rico, Mayaguez .This paper presents the design of two field lysimeter used to study the fate and transport behavior of ERC in the field subjected to varying uncontrolled subtropical environmental conditions in two different soils. Both lysimeters incorporate pressure and concentration sampling ports, thermocouples, and a drainage system. Hydrus-2D was used to simulate soil moisture and drainage in the lysimeter for average environmental conditions in the study for the two soils used. The field lysimeters allow collection and monitoring of spatial and temporal ERC concentrations under variable, uncontrolled environmental conditions.

  19. Stability of exempt chemical surety materiel (XCSM) in commonly used diluents under routine storage conditions

    SciTech Connect

    Hayes, T.L.; Chaffins, S.A.; Kohne, J.W.; Murphy, T.L.; Cunningham, R.I.

    1993-05-13

    Due to either the extreme toxicity of chemical surety materiel (CSM) or the limitations of the experimental facility, it is often required that CSM be diluted before use. The requisite of selecting both a non-toxic diluent and a diluent that does not bias the proposed experiment often results in use of 'non-standard' analytical solvents. These 'nonstandard' solvents include distilled water, drug vehicles, and culture media. The lack of sufficient agent/solvent stability information in these solutions is of major concern to both experimental designers and data reviewers. The objectives of this task were to determine the shelf life of exempt concentrations of GA, GB, GD, VX, and HD in selected diluents at prescribed concentrations and temperatures, and to assemble this information into a database. Efforts included the development of analytical methods necessary to perform these stability experiments and the compilation of results into a working database. The database, once completed, will be made available to XCSM researchers and will be updated as necessary.

  20. Monitoring and physical-chemical modeling of conditions of natural surface and underground waters forming in the Kola North.

    PubMed

    Mazukhina, Svetlana I; Masloboev, Vladimir A; Chudnenko, Konstantin V; Bychinsky, Valeriy A; Svetlov, Anton V; Muraviev, Sergey V

    2012-01-01

    Processes of surface and underground water forming in the Khibiny massif have been studied using a physical-chemical model of the "water-rock-atmosphere-organic substance" system. The obtained model solutions are indicative of the fact that formation of surface and underground water of the Khibiny massif takes place on the whole in the framework of the considered system without attracting a hypothetical outside source of pollutants. The results are of practical and methodological importance for assessment of prediction of the man-induced impact on water systems in conditions of Subarctic. PMID:22416860

  1. Emission characteristics of nitrogen- and sulfur-containing odorous compounds during different sewage sludge chemical conditioning processes.

    PubMed

    Liu, Huan; Luo, Guang-Qian; Hu, Hong-Yun; Zhang, Qiang; Yang, Jia-Kuan; Yao, Hong

    2012-10-15

    Chemical conditioners are often used to enhance sewage sludge dewaterability through altering sludge properties and flocs structure, both affect odorous compounds emissions not only during sludge conditioning but also in subsequent sludge disposal. This study was to investigate emission characteristics of ammonia (NH(3)), sulfur dioxide (SO(2)), hydrogen sulfide (H(2)S) and carbonyl sulfide (COS) generated from sewage sludge conditioned by three representative conditioners, i.e., organic polymers, iron salts and skeleton builders, F-S (Fenton's reagent and skeleton builders) composite conditioner. The results demonstrate that polyacrylamide (PAM) has an insignificant effect on emission characteristics of nitrogen- and sulfur-containing odorous compounds, because the properties, sulfur and nitrogen speciations are similar in PAM-conditioned sludge and raw sludge (RS). Significant increases of SO(2) and H(2)S emissions in the H(2)SO(4) conditioning process were observed due to the accelerated decomposition of sulfur-containing amino acids in acidic environment. Fenton peroxidation facilitates the formation of COS. CaO can reduce sulfur-containing gases emission via generation of calcium sulfate. However, under strong alkaline conditions, free ammonia or protonated amine in sludge can be easily converted to volatile ammonia, resulting in a significant release of NH(3). PMID:22902143

  2. Low-thrust chemical propulsion system propellant expulsion and thermal conditioning study

    NASA Technical Reports Server (NTRS)

    Merino, F.; Wakabayashi, I.; Pleasant, R. L.; Hill, M.

    1982-01-01

    Thermal conditioning systems for satisfying engine net positive suction pressure (NPSP) requirements, and propellant expulsion systems for achieving propellant dump during a return-to-launch site (RTLS) abort were studied for LH2/LO2 and LCH4/LO2 upper stage propellant combinations. A state-of-the-art thermal conditioning system employing helium injection beneath the liquid surface shows the lowest weight penalty for LO2 and LCH4. A technology system incorporating a thermal subcooler (heat exchanger) for engine NPSP results in the lowest weight penalty for the LH2 tank. A preliminary design of two state-of-the-art and two new technology systems indicates a weight penalty difference too small to warrant development of a LH2 thermal subcooler. Analysis results showed that the LH2/LO2 propellant expulsion system is optimized for maximum dump line diameters, whereas the LCH4/LO2 system is optimized for minimum dump line diameter (LCH4) and maximum dump line diameter (LO2). The primary uncertainty is the accurate determination of two-phase flow rates through the dump system; experimentation is not recommended because this uncertainty is not considered significant.

  3. Chemical profiling of Jatropha tissues under different torrefaction conditions: application to biomass waste recovery.

    PubMed

    Watanabe, Taiji; Shino, Amiu; Akashi, Kinya; Kikuchi, Jun

    2014-01-01

    Gradual depletion of the world petroleum reserves and the impact of environmental pollution highlight the importance of developing alternative energy resources such as plant biomass. To address these issues, intensive research has focused on the plant Jatropha curcas, which serves as a rich source of biodiesel because of its high seed oil content. However, producing biodiesel from Jatropha generates large amounts of biomass waste that are difficult to use. Therefore, the objective of our research was to analyze the effects of different conditions of torrefaction on Jatropha biomass. Six different types of Jatropha tissues (seed coat, kernel, stem, xylem, bark, and leaf) were torrefied at four different temperature conditions (200°C, 250°C, 300°C, and 350°C), and changes in the metabolite composition of the torrefied products were determined by Fourier transform-infrared spectroscopy and nuclear magnetic resonance analyses. Cellulose was gradually converted to oligosaccharides in the temperature range of 200°C-300°C and completely degraded at 350°C. Hemicellulose residues showed different degradation patterns depending on the tissue, whereas glucuronoxylan efficiently decomposed between 300°C and 350°C. Heat-induced depolymerization of starch to maltodextrin started between 200°C and 250°C, and oligomer sugar structure degradation occurred at higher temperatures. Lignin degraded at each temperature, e.g., syringyl (S) degraded at lower temperatures than guaiacyl (G). Finally, the toxic compound phorbol ester degraded gradually starting at 235°C and efficiently just below 300°C. These results suggest that torrefaction is a feasible treatment for further processing of residual biomass to biorefinery stock or fertilizer. PMID:25191879

  4. Chemical Profiling of Jatropha Tissues under Different Torrefaction Conditions: Application to Biomass Waste Recovery

    PubMed Central

    Watanabe, Taiji; Shino, Amiu; Akashi, Kinya; Kikuchi, Jun

    2014-01-01

    Gradual depletion of the world petroleum reserves and the impact of environmental pollution highlight the importance of developing alternative energy resources such as plant biomass. To address these issues, intensive research has focused on the plant Jatropha curcas, which serves as a rich source of biodiesel because of its high seed oil content. However, producing biodiesel from Jatropha generates large amounts of biomass waste that are difficult to use. Therefore, the objective of our research was to analyze the effects of different conditions of torrefaction on Jatropha biomass. Six different types of Jatropha tissues (seed coat, kernel, stem, xylem, bark, and leaf) were torrefied at four different temperature conditions (200°C, 250°C, 300°C, and 350°C), and changes in the metabolite composition of the torrefied products were determined by Fourier transform-infrared spectroscopy and nuclear magnetic resonance analyses. Cellulose was gradually converted to oligosaccharides in the temperature range of 200°C–300°C and completely degraded at 350°C. Hemicellulose residues showed different degradation patterns depending on the tissue, whereas glucuronoxylan efficiently decomposed between 300°C and 350°C. Heat-induced depolymerization of starch to maltodextrin started between 200°C and 250°C, and oligomer sugar structure degradation occurred at higher temperatures. Lignin degraded at each temperature, e.g., syringyl (S) degraded at lower temperatures than guaiacyl (G). Finally, the toxic compound phorbol ester degraded gradually starting at 235°C and efficiently just below 300°C. These results suggest that torrefaction is a feasible treatment for further processing of residual biomass to biorefinery stock or fertilizer. PMID:25191879

  5. Effect of pH and chemical mechanical planarization process conditions on the copper–benzotriazole complex formation

    NASA Astrophysics Data System (ADS)

    Cho, Byoung-Jun; Kim, Jin-Yong; Hamada, Satomi; Shima, Shohei; Park, Jin-Goo

    2016-06-01

    Benzotriazole (BTA) has been used to protect copper (Cu) from corrosion during Cu chemical mechanical planarization (CMP) processes. However, an undesirable Cu–BTA complex is deposited after Cu CMP processes and it should be completely removed at post-Cu CMP cleaning for next fabrication process. Therefore, it is very important to understand of Cu–BTA complex formation behavior for its applications such as Cu CMP and post-Cu CMP cleaning. The present study investigated the effect of pH and polisher conditions on the formation of Cu–BTA complex layers using electrochemical techniques (potentiodynamic polarization and electrochemical impedance spectroscopy) and the surface contact angle. The wettability was not a significant factor for the polishing interface, as no difference in the contact angles was observed for these processes. Both electrochemical techniques revealed that BTA had a unique advantage of long-term protection for Cu corrosion in an acidic condition (pH 3).

  6. Exhaust emissions from gasoline-fuelled light duty vehicles operated in different driving conditions: A chemical and biological characterization

    NASA Astrophysics Data System (ADS)

    Westerholm, Roger; Almén, Jacob; Li, Hang; Rannug, Ulf; Rosén, Åke

    Chemical analysis and mutagenicity tests on Salmonella typtimurium strains TA 98 and TA 100 (Ames test) of exhaust emissions from five passengers vehicles, with or without a three-way catalyst, have been carried out to obtain emission factors and to characterize exhaust emissions. Both constant cruising speeds and transient driving conditions were investigated, regulated CO, HC, NO x and particulates, as well as unregulated pollutants, were analysed. The following unregulated pollutants were measured: particle-associated polycyclic aromatic hydrocarbons (PAH), 1-nitropyrene, light aromatics and light oxygenates. In total, 39 individual compounds were assayed. Emissions from catalyst-equipped vehicles showed a dramatic decrease compared with those from the vehicle without a catalyst. An emission dependency of both regulated and unregulated pollutants and biological activity on driving conditions were determined. An increased emission of PAH, 1-nitropyrene, particulates and mutagenic activity was found with a higher cruising speed.

  7. Synthesis of SF5CF2-Containing Enones and Instability of This Group in Specific Chemical Environments and Reaction Conditions.

    PubMed

    Dudziński, Piotr; Matsnev, Andrej V; Thrasher, Joseph S; Haufe, Günter

    2016-06-01

    The chemistry of the SF5CF2 moiety has been scarcely investigated. In this report, we present synthetic pathways to a variety of SF5CF2-substituted compounds starting from vinyl ethers and SF5CF2C(O)Cl. In specific chemical environments and under particular reaction conditions, the SF5CF2 moiety is unstable in downstream products resulting in the elimination of the SF5(-) anion and its decomposition to SF4 and F(-). Surprisingly, the formed F(-) can attack the intermediate difluorovinyl moiety to form trifluoromethyl substituted products. This appears to happen when an intermediate neighboring group participation involving a double bond is possible. Under slightly different conditions, the reaction stops at the stage of a difluorovinyl compound. PMID:27159371

  8. Chemical and Physical Environmental Conditions Underneath Mat- and Canopy-Forming Macroalgae, and Their Effects on Understorey Corals

    PubMed Central

    Hauri, Claudine; Fabricius, Katharina E.; Schaffelke, Britta; Humphrey, Craig

    2010-01-01

    Disturbed coral reefs are often dominated by dense mat- or canopy-forming assemblages of macroalgae. This study investigated how such dense macroalgal assemblages change the chemical and physical microenvironment for understorey corals, and how the altered environmental conditions affect the physiological performance of corals. Field measurements were conducted on macroalgal-dominated inshore reefs in the Great Barrier Reef in quadrats with macroalgal biomass ranging from 235 to 1029 g DW m−2 dry weight. Underneath mat-forming assemblages, the mean concentration of dissolved oxygen was reduced by 26% and irradiance by 96% compared with conditions above the mat, while concentrations of dissolved organic carbon and soluble reactive phosphorous increased by 26% and 267%, respectively. The difference was significant but less pronounced under canopy-forming assemblages. Dissolved oxygen declined and dissolved inorganic carbon and alkalinity increased with increasing algal biomass underneath mat-forming but not under canopy-forming assemblages. The responses of corals to conditions similar to those found underneath algal assemblages were investigated in an aquarium experiment. Coral nubbins of the species Acropora millepora showed reduced photosynthetic yields and increased RNA/DNA ratios when exposed to conditions simulating those underneath assemblages (pre-incubating seawater with macroalgae, and shading). The magnitude of these stress responses increased with increasing proportion of pre-incubated algal water. Our study shows that mat-forming and, to a lesser extent, canopy-forming macroalgal assemblages alter the physical and chemical microenvironment sufficiently to directly and detrimentally affect the metabolism of corals, potentially impeding reef recovery from algal to coral-dominated states after disturbance. Macroalgal dominance on coral reefs therefore simultaneously represents a consequence and cause of coral reef degradation. PMID:20856882

  9. Electronic and chemical structure of the H2O/GaN(0001) interface under ambient conditions

    NASA Astrophysics Data System (ADS)

    Zhang, Xueqiang; Ptasinska, Sylwia

    2016-04-01

    We employed ambient pressure X-ray photoelectron spectroscopy to investigate the electronic and chemical properties of the H2O/GaN(0001) interface under elevated pressures and/or temperatures. A pristine GaN(0001) surface exhibited upward band bending, which was partially flattened when exposed to H2O at room temperature. However, the GaN surface work function was slightly reduced due to the adsorption of molecular H2O and its dissociation products. At elevated temperatures, a negative charge generated on the surface by a vigorous H2O/GaN interfacial chemistry induced an increase in both the surface work function and upward band bending. We tracked the dissociative adsorption of H2O onto the GaN(0001) surface by recording the core-level photoemission spectra and obtained the electronic and chemical properties at the H2O/GaN interface under operando conditions. Our results suggest a strong correlation between the electronic and chemical properties of the material surface, and we expect that their evolutions lead to significantly different properties at the electrolyte/electrode interface in a photoelectrochemical solar cell.

  10. Electronic and chemical structure of the H2O/GaN(0001) interface under ambient conditions.

    PubMed

    Zhang, Xueqiang; Ptasinska, Sylwia

    2016-01-01

    We employed ambient pressure X-ray photoelectron spectroscopy to investigate the electronic and chemical properties of the H2O/GaN(0001) interface under elevated pressures and/or temperatures. A pristine GaN(0001) surface exhibited upward band bending, which was partially flattened when exposed to H2O at room temperature. However, the GaN surface work function was slightly reduced due to the adsorption of molecular H2O and its dissociation products. At elevated temperatures, a negative charge generated on the surface by a vigorous H2O/GaN interfacial chemistry induced an increase in both the surface work function and upward band bending. We tracked the dissociative adsorption of H2O onto the GaN(0001) surface by recording the core-level photoemission spectra and obtained the electronic and chemical properties at the H2O/GaN interface under operando conditions. Our results suggest a strong correlation between the electronic and chemical properties of the material surface, and we expect that their evolutions lead to significantly different properties at the electrolyte/electrode interface in a photoelectrochemical solar cell. PMID:27108711

  11. Electronic and chemical structure of the H2O/GaN(0001) interface under ambient conditions

    PubMed Central

    Zhang, Xueqiang; Ptasinska, Sylwia

    2016-01-01

    We employed ambient pressure X-ray photoelectron spectroscopy to investigate the electronic and chemical properties of the H2O/GaN(0001) interface under elevated pressures and/or temperatures. A pristine GaN(0001) surface exhibited upward band bending, which was partially flattened when exposed to H2O at room temperature. However, the GaN surface work function was slightly reduced due to the adsorption of molecular H2O and its dissociation products. At elevated temperatures, a negative charge generated on the surface by a vigorous H2O/GaN interfacial chemistry induced an increase in both the surface work function and upward band bending. We tracked the dissociative adsorption of H2O onto the GaN(0001) surface by recording the core-level photoemission spectra and obtained the electronic and chemical properties at the H2O/GaN interface under operando conditions. Our results suggest a strong correlation between the electronic and chemical properties of the material surface, and we expect that their evolutions lead to significantly different properties at the electrolyte/electrode interface in a photoelectrochemical solar cell. PMID:27108711

  12. Electronic and chemical structure of the H2O/GaN(0001) interface under ambient conditions

    DOE PAGESBeta

    Zhang, Xueqiang; Ptasinska, Sylwia

    2016-04-25

    We employed ambient pressure X-ray photoelectron spectroscopy to investigate the electronic and chemical properties of the H2O/GaN(0001) interface under elevated pressures and/or temperatures. A pristine GaN(0001) surface exhibited upward band bending, which was partially flattened when exposed to H2O at room temperature. However, the GaN surface work function was slightly reduced due to the adsorption of molecular H2O and its dissociation products. At elevated temperatures, a negative charge generated on the surface by a vigorous H2O/GaN interfacial chemistry induced an increase in both the surface work function and upward band bending. We tracked the dissociative adsorption of H2O onto themore » GaN(0001) surface by recording the core-level photoemission spectra and obtained the electronic and chemical properties at the H2O/GaN interface under operando conditions. In conclusion, our results suggest a strong correlation between the electronic and chemical properties of the material surface, and we expect that their evolutions lead to significantly different properties at the electrolyte/ electrode interface in a photoelectrochemical solar cell.« less

  13. Control of transport and magnetism in ferromagnetic semiconducting superlattices through growth conditions and chemical surface effects

    NASA Astrophysics Data System (ADS)

    Kreutz, Theodore Carlton

    2003-10-01

    addition of chemical adsorbates. We find that we can reduce the Curie temperature by over 50 K. The reduction is linked to how well ordered the adsorbate is.

  14. Tenascin C Promotes Hematoendothelial Development and T Lymphoid Commitment from Human Pluripotent Stem Cells in Chemically Defined Conditions

    PubMed Central

    Uenishi, Gene; Theisen, Derek; Lee, Jeong-Hee; Kumar, Akhilesh; Raymond, Matt; Vodyanik, Maxim; Swanson, Scott; Stewart, Ron; Thomson, James; Slukvin, Igor

    2014-01-01

    Summary The recent identification of hemogenic endothelium (HE) in human pluripotent stem cell (hPSC) cultures presents opportunities to investigate signaling pathways that are essential for blood development from endothelium and provides an exploratory platform for de novo generation of hematopoietic stem cells (HSCs). However, the use of poorly defined human or animal components limits the utility of the current differentiation systems for studying specific growth factors required for HE induction and manufacturing clinical-grade therapeutic blood cells. Here, we identified chemically defined conditions required to produce HE from hPSCs growing in Essential 8 (E8) medium and showed that Tenascin C (TenC), an extracellular matrix protein associated with HSC niches, strongly promotes HE and definitive hematopoiesis in this system. hPSCs differentiated in chemically defined conditions undergo stages of development similar to those previously described in hPSCs cocultured on OP9 feeders, including the formation of VE-Cadherin+CD73−CD235a/CD43− HE and hematopoietic progenitors with myeloid and T lymphoid potential. PMID:25448067

  15. Physical properties, chemical composition, and cloud forming potential of particulate emissions from a marine diesel engine at various load conditions.

    PubMed

    Petzold, A; Weingartner, E; Hasselbach, J; Lauer, P; Kurok, C; Fleischer, F

    2010-05-15

    Particulate matter (PM) emissions from one serial 4-stroke medium-speed marine diesel engine were measured for load conditions from 10% to 110% in test rig studies using heavy fuel oil (HFO). Testing the engine across its entire load range permitted the scaling of exhaust PM properties with load. Emission factors for particle number, particle mass, and chemical compounds were determined. The potential of particles to form cloud droplets (cloud condensation nuclei, CCN) was calculated from chemical composition and particle size. Number emission factors are (3.43 +/- 1.26) x 10(16) (kg fuel)(-1) at 85-110% load and (1.06 +/- 0.10) x 10(16) (kg fuel)(-1) at 10% load. CCN emission factors of 1-6 x 10(14) (kg fuel)(-1) are at the lower bound of data reported in the literature. From combined thermal and optical methods, black carbon (BC) emission factors of 40-60 mg/(kg fuel) were determined for 85-100% load and 370 mg/(kg fuel) for 10% load. The engine load dependence of the conversion efficiency for fuel sulfur into sulfate of (1.08 +/- 0.15)% at engine idle to (3.85 +/- 0.41)% at cruise may serve as input to global emission calculations for various load conditions. PMID:20402501

  16. Evaluation of the chemical, physical, and biological conditions of the Alamosa River and associated tributaries

    SciTech Connect

    Willingham, W.T.; Parrish, L.P.; Schroeder, W.C.

    1995-12-31

    This study focused on the Summitville Mine Site, an abandoned cyanide heap-leach facility that discharges into the upper Alamosa River by way of the Wightman Fork, some five miles upstream from its confluence with the Alamosa River. Environmental data have been collected from the Alamosa River from its headwaters in the Rocky Mountains to its confluence with the Rio Grande River, Colorado. To date, environmental data have been collected in 1991, 1993, and July and September 1994. Water column and sediment chemistry, flow estimates and toxicity test data from more comprehensive environmental sampling events in July and September 1994 were used, in conjunction with other environmental data including in-stream biological data and physical habitat, to determine what impact, if any, the Summitville Superfund site was having on the aquatic life resources within the Alamosa River drainage, Comparisons of macroinvertebrate samples collected in July and September revealed difficulties relating impacts that occurred earlier in the summer, when heavy metal concentrations in the water column were high, to impacts that were noted in the fall, when heavy metal concentrations were lower. The macroinvertebrate community was reduced in numbers in the fall. However, water column chemistry and toxicity testing indicated improved conditions, when compared to the July sampling results. Possible reasons for the differences will be examined and suggestions will be made concerning additional sampling that might provide answers to the differences observed.

  17. Effect of extraction conditions on the yield and chemical properties of pectin from cocoa husks.

    PubMed

    Chan, Siew-Yin; Choo, Wee-Sim

    2013-12-15

    Different extraction conditions were applied to investigate the effect of temperature, extraction time and substrate-extractant ratio on pectin extraction from cocoa husks. Pectin was extracted from cocoa husks using water, citric acid at pH 2.5 or 4.0, or hydrochloric acid at pH 2.5 or 4.0. Temperature, extraction time and substrate-extractant ratio affected the yields, uronic acid contents, degrees of methylation (DM) and degrees of acetylation (DA) of the extracted pectins using the five extractants differently. The yields and uronic acid contents of the extracted pectins ranged from 3.38-7.62% to 31.19-65.20%, respectively. The DM and DA of the extracted pectins ranged from 7.17-57.86% to 1.01-3.48%, respectively. The highest yield of pectin (7.62%) was obtained using citric acid at pH 2.5 [1:25 (w/v)] at 95 °C for 3.0 h. The highest uronic acid content (65.20%) in the pectin was obtained using water [1:25 (w/v)] at 95 °C for 3.0 h. PMID:23993545

  18. Photoacoustic physio-chemical analysis of liver conditions in animal and human subjects

    NASA Astrophysics Data System (ADS)

    Wang, Xueding; Xu, Guan; Tian, Chao; Wan, Shanshan; Welling, Theodore H.; Lok, Anna S. F.; Rubin, Jonathan M.

    2016-03-01

    Non-alcoholic fatty liver disease (NAFLD) is a common liver disease affecting 30% of the population in the United States. Biopsy is the gold standard for diagnosing NAFLD. Liver histology assesses the amount of fat, and determines type and extent of cell injury, inflammation and fibrosis. However, liver biopsy is invasive and is limited by sampling error. Current radiological diagnostic modalities can evaluate the 'physical' morphology in liver by quantifying the backscattered US signals, but cannot interrogate the 'histochemical' components forming these backscatterers. For example, ultrasound (US) imaging can detect the presence of fat but cannot differentiate steatosis alone from steatohepatitis. Our previous study of photoacoustic physiochemical analysis (PAPCA) has demonstrated that this method can characterize the histological changes in livers during the progression of NAFLD in animal models. In this study, we will further validate PAPCA with human livers. Ex vivo human liver samples with steatosis, fibrosis and cirrhosis will be scanned using optical illumination at wavelengths of 680-1700 nm and compared to histology results. In vivo study on human subjects with confirmed steatosis is planned using our PA-ultrasound (US) parallel imaging system based on Verasonic US imaging flatform with an L7-4 probe. 10 mJ/cm2 per pulse optical energy at 755 nm will be delivered to the skin surface, which is under the safety limit of American National Standard Institute. Preliminary study with ex vivo human tissue has demonstrated the potential of the proposed approach in differentiating human liver conditions.

  19. Interaction between chitosan and oil under stomach and duodenal digestive chemical conditions.

    PubMed

    Rodríguez, María Susana; Albertengo, Liliana Elena

    2005-11-01

    Chitosan, the N acetylated derivative of chitin, has an effect on the absorption of dietary lipids, but there is not enough scientific knowledge about the mechanism. To study the interaction between chitosan and oil, the action of this biopolymer has been evaluated through an experimental model of the stomach and duodenum tract, although the enzimatic activity had not been evaluated. We microscopically confirmed that chitosan in a hychloridic acid medium (pH 1.0-2.0) emulsified lipids and the emulsion was a water in oil in water type (w/o/w). When the pH value and speed of agitation were increased to mirror the duodenum medium conditions under which lipids are absorbed, the emulsion capacity was better with an increased number of droplets and the emulsion continued as the w/o/w type. At pH 6.2, chitosan precipitated and lipids were entrapped in the formed flocculus. The binding oil was quantitatively determined, and we also demonstrate that a larger oil quantity induced less retention, while the chitosan characteristics had no influence. These observations allow us to postulate that the interaction between chitosan and oil inhibited duodenal absorption and enhanced lipid excretion. PMID:16306685

  20. Effects of spray-drying conditions on the chemical, physical, and sensory properties of cheese powder.

    PubMed

    Koca, Nurcan; Erbay, Zafer; Kaymak-Ertekin, Figen

    2015-05-01

    Dairy powders are produced to increase the shelf life of fresh dairy products and for use as flavoring agents. In this study, 24 cheese powders produced under 7 different conditions were used to investigate the effects of spray-drying parameters (e.g., inlet air temperature, atomization pressure, and outlet air temperature) on the quality of white cheese powder. Composition, color, physical properties, reconstitution, and sensory characteristics of white cheese powders were determined. The results revealed that the white cheese powders produced in this study had low moisture content ratios and water activity values. High outlet air temperatures caused browning and enhanced Maillard reactions. Additionally, high outlet air temperatures increased wettability and dispersibility and decreased the solubility of white cheese powders. Free fat content was positively correlated with inlet air temperature and negatively correlated with outlet air temperature and atomization pressure. Sensory analyses revealed that white cheese powder samples had acceptable sensory characteristics with the exception of the sample produced at an outlet air temperature of 100°C, which had high scores for scorched flavor and color and low scores for cheese flavor. PMID:25771045

  1. Dynamics-based selective 2D (1)H/(1)H chemical shift correlation spectroscopy under ultrafast MAS conditions.

    PubMed

    Zhang, Rongchun; Ramamoorthy, Ayyalusamy

    2015-05-28

    Dynamics plays important roles in determining the physical, chemical, and functional properties of a variety of chemical and biological materials. However, a material (such as a polymer) generally has mobile and rigid regions in order to have high strength and toughness at the same time. Therefore, it is difficult to measure the role of mobile phase without being affected by the rigid components. Herein, we propose a highly sensitive solid-state NMR approach that utilizes a dipolar-coupling based filter (composed of 12 equally spaced 90° RF pulses) to selectively measure the correlation of (1)H chemical shifts from the mobile regions of a material. It is interesting to find that the rotor-synchronized dipolar filter strength decreases with increasing inter-pulse delay between the 90° pulses, whereas the dipolar filter strength increases with increasing inter-pulse delay under static conditions. In this study, we also demonstrate the unique advantages of proton-detection under ultrafast magic-angle-spinning conditions to enhance the spectral resolution and sensitivity for studies on small molecules as well as multi-phase polymers. Our results further demonstrate the use of finite-pulse radio-frequency driven recoupling pulse sequence to efficiently recouple weak proton-proton dipolar couplings in the dynamic regions of a molecule and to facilitate the fast acquisition of (1)H/(1)H correlation spectrum compared to the traditional 2D NOESY (Nuclear Overhauser effect spectroscopy) experiment. We believe that the proposed approach is beneficial to study mobile components in multi-phase systems, such as block copolymers, polymer blends, nanocomposites, heterogeneous amyloid mixture of oligomers and fibers, and other materials. PMID:26026440

  2. Collisions of small ice particles under microgravity conditions. II. Does the chemical composition of the ice change the collisional properties?

    NASA Astrophysics Data System (ADS)

    Hill, C. R.; Heißelmann, D.; Blum, J.; Fraser, H. J.

    2015-03-01

    Context. Understanding the collisional properties of ice is important for understanding both the early stages of planet formation and the evolution of planetary ring systems. Simple chemicals such as methanol and formic acid are known to be present in cold protostellar regions alongside the dominant water ice; they are also likely to be incorporated into planets which form in protoplanetary disks, and planetary ring systems. However, the effect of the chemical composition of the ice on its collisional properties has not yet been studied. Aims: Collisions of 1.5 cm ice spheres composed of pure crystalline water ice, water with 5% methanol, and water with 5% formic acid were investigated to determine the effect of the ice composition on the collisional outcomes. Methods: The collisions were conducted in a dedicated experimental instrument, operated under microgravity conditions, at relative particle impact velocities between 0.01 and 0.19 ms-1, temperatures between 131 and 160 K and a pressure of around 10-5 mbar. Results: A range of coefficients of restitution were found, with no correlation between this and the chemical composition, relative impact velocity, or temperature. Conclusions: We conclude that the chemical composition of the ice (at the level of 95% water ice and 5% methanol or formic acid) does not affect the collisional properties at these temperatures and pressures due to the inability of surface wetting to take place. At a level of 5% methanol or formic acid, the structure is likely to be dominated by crystalline water ice, leading to no change in collisional properties. The surface roughness of the particles is the dominant factor in explaining the range of coefficients of restitution.

  3. Chemical speciation of neptunium(VI) under strongly alkaline conditions. Structure, composition, and oxo ligand exchange.

    PubMed

    Clark, David L; Conradson, Steven D; Donohoe, Robert J; Gordon, Pamela L; Keogh, D Webster; Palmer, Phillip D; Scott, Brian L; Tait, C Drew

    2013-04-01

    Hexavalent neptunium can be solubilized in 0.5-3.5 M aqueous MOH (M = Li(+), Na(+), NMe4(+) = TMA(+)) solutions. Single crystals were obtained from cooling of a dilute solution of Co(NH3)6Cl3 and NpO2(2+) in 3.5 M [N(Me)4]OH to 5 °C. A single-crystal X-ray diffraction study revealed the molecular formula of [Co(NH3)6]2[NpO2(OH)4]3·H2O, isostructural with the uranium analogue. The asymmetric unit contains three distinct NpO2(OH)4(2-) ions, each with pseudooctahedral coordination geometry with trans-oxo ligands. The average Np═O and Np-OH distances were determined to be 1.80(1) and 2.24(1) Å, respectively. EXAFS data and fits at the Np L(III)-edge on solid [Co(NH3)6]2[NpO2(OH)4]3·H2O and aqueous solutions of NpO2(2+) in 2.5 and 3.5 M (TMA)OH revealed bond lengths nearly identical with those determined by X-ray diffraction but with an increase in the number of equatorial ligands with increasing (TMA)OH concentration. Raman spectra of single crystals of [Co(NH3)6]2[NpO2(OH)4]3·H2O reveal a ν1(O═Np═O) symmetric stretch at 741 cm(-1). Raman spectra of NpO2(2+) recorded in a 0.6-2.2 M LiOH solution reveal a single ν1 frequency of 769 cm(-1). Facile exchange of the neptunyl oxo ligands with the water solvent was also observed with Raman spectroscopy performed with (16)O- and (18)O-enriched water solvent. The combination of EXAFS and Raman data suggests that NpO2(OH)4(2-) is the dominant solution species under the conditions of study and that a small amount of a second species, NpO2(OH)5(3-), may also be present at higher alkalinity. Crystal data for [Co(NH3)6]2[NpO2(OH)4]3·H2O: monoclinic, space group C2/c, a = 17.344(4) Å, b = 12.177(3) Å, c = 15.273 Å, β = 120.17(2)°, Z = 4, R1 = 0.0359, wR2 = 0.0729. PMID:23485079

  4. Effects of Calcination and Milling Process Conditions for Ceria Slurry on Shallow-Trench-Isolation Chemical-Mechanical Polishing Performance

    NASA Astrophysics Data System (ADS)

    Kim, Jun-Seok; Kang, Hyun-Goo; Kanemoto, Manabu; Paik, Ungyu; Park, Jea-Gun

    2007-12-01

    To improve the performance of shallow trench isolation chemical-mechanical polishing (STI-CMP) in terms of the removal selectivity of oxide and nitride films and the formation of surface defects, we investigated the effects of the calcination and milling process conditions during ceria slurry synthesis. We have focused on the effects of particle size distribution, the large-particle size, and the dispersion stability in a ceria slurry. We determined the optimum bead size for milling and appropriate calcination temperatures in order to obtain a reasonable particle distribution, with lower numbers of fine primary particles and large, agglomerated particles, in ceria slurry. This was achieved by reducing the quantity of aggregated particles during milling and two-step calcination process generating higher-density particles. These results can be qualitatively explained by abrasive collisions occurring between the milling beads and the decarbonation of cerium carbonate through diffusion during the manufacturing process used for the ceria slurry.

  5. Efficiency of some soil bacteria for chemical oxygen demand reduction of synthetic chlorsulfuron solutions under agiated culture conditions.

    PubMed

    Erguven, G O; Yildirim, N

    2016-01-01

    This study searches the efficiency of certain soil bacteria on chemical oxygen demand (COD) reduction of synthetic chlorsulfuron solutions under agitated culture conditions. It also aims to determine the turbidity of liquid culture medium with chlorsulfuron during bacterial incubation for 120 hours. As a result the highest and lowest COD removal efficiency of bacteria was determined for Bacillus simplex as 94% and for Micrococcus luteus as 70%, respectively at the end of the 96th hour. It was found that COD removal efficiency showed certain differences depend on the bacterial species. It was also observed that B. simplex had the highest COD removal efficiency and it was a suitable bacterium species for bioremediation of a chlorsulfuron contaminated soils. PMID:27262810

  6. Effect of vacuum conditions and plasma concentration on the chemical composition and adhesion of vacuum-plasma coatings

    NASA Astrophysics Data System (ADS)

    Borisov, D. P.; Kuznetsov, V. M.; Slabodchikov, V. A.

    2015-11-01

    The paper reports on the chemical composition of titanium nitride (TiN) and silicon (Si) coatings deposited with a new technological vacuum plasma setup which comprises magnetron sputtering systems, arc evaporators, and an efficient plasma generator. It is shown that due to highly clean vacuum conditions and highly clean surface treatment in the gas discharge plasma, both the coating-substrate interface and the coatings as such are almost free from oxygen and carbon. It is found that the coating-substrate interface represents a layer of thickness ≥ 60 nm formed through vacuum plasma mixing of the coating and substrate materials. The TiN coatings obtained on the new equipment display a higher adhesion compared to brass coatings deposited by industrial technologies via intermediate titanium oxide layers. It is concluded that the designed vacuum plasma equipment allows efficient surface modification of materials and articles by vacuum plasma immersion processes.

  7. Studies on the phytoplankton populations and physico-chemical conditions of treated sewage discharged into Lake Manzala in Egypt.

    PubMed

    el-Naggar, M E; Shaaban-Dessouki, S A; Abdel-Hamid, M I; Aly, E M

    1998-04-01

    Over a full year, the phytoplankton populations and physico-chemical conditions of treated sewage discharged into Lake Manzala in Egypt were investigated. Sixty-seven species of algae were identified, 18 Cyanophyta (Cyanobacteria), 19 Chlorophyta, 21 Bacillariophyta, 6 Euglenophyta, 2 Cryptophyta and one species Pyrrhophyta. Nitzschia (6 spp.), Scenedesmus (6 spp.), Navicula (4 spp.), Oscillatoria (4 spp.) and Euglena (4 spp.) were the most common genera. A remarkable seasonal variation in species composition and standing crop of the phytoplankton populations was noted during the study. The total phytoplankton standing crop appeared to be mainly dependent on the growth of certain species viz., Oscillatoria chalybea, O. princepes, O. tenuis, Microcystis aeruginosa, Anabaena constricta (Cyanophyta), Nitzschia obtusa, Bacillaria paradoxa, Cocconeis placentula, Cyclotella meneghiniana (Bacillariophyta), Pandorina morum, Volvox sp. (Chlorophyta) and Phacus curvicauda (Euglenophyta). The continuous presence of Anabaena constricta and Nitzschia palea was recorded in the treated sewage. The least represented algal divisions were Pyrrhophyta and Cryptophyta, both in terms of quality and quantity. The data indicate that the secondary effluents were unstable in their chemical features and grossly polluted. Therefore, the treatment systems must treat the discharged sewage to a tertiary level before discharging into Lake Manzala. PMID:9579343

  8. Kinetic studies of chemical shrinkage and residual stress formation in thermoset epoxy adhesives under confined curing conditions

    NASA Astrophysics Data System (ADS)

    Schumann, M.; Geiß, P. L.

    2015-05-01

    Faultless processing of thermoset polymers in demanding applications requires a profound mastering of the curing kinetics considering both the physico-chemical changes in the transition from the liquid to the solid state and the consolidation of the polymers network in the diffusion controlled curing regime past the gel point. Especially in adhesive joints shrinkage stress occurring at an early state of the curing process under confined conditions is likely to cause defects due to local debonding and thus reduce their strength and durability1. Rheometry is considered the method of choice to investigate the change of elastic and viscous properties in the progress of curing. Drawbacks however relate to experimental challenges in accessing the full range of kinetic parameters of thermoset resins with low initial viscosity from the very beginning of the curing reaction to the post-cure consolidation of the polymer due to the formation of secondary chemical bonds. Therefore the scope of this study was to interrelate rheological data with results from in-situ measurements of the shrinkage stress formation in adhesive joints and with the change of refractive index in the progress of curing. This combination of different methods has shown to be valuable in gaining advanced insight into the kinetics of the curing reaction. The experimental results are based on a multi component thermoset epoxy-amine adhesive.

  9. Identification of morphological and chemical markers of dry- and wet-season conditions in female Anopheles gambiae mosquitoes

    PubMed Central

    2014-01-01

    Background Increased understanding of the dry-season survival mechanisms of Anopheles gambiae in semi-arid regions could benefit vector control efforts by identifying weak links in the transmission cycle of malaria. In this study, we examined the effect of photoperiod and relative humidity on morphologic and chemical traits known to control water loss in mosquitoes. Methods Anopheles gambiae body size (indexed by wing length), mesothoracic spiracle size, and cuticular hydrocarbon composition (both standardized by body size) were examined in mosquitoes raised from eggs exposed to short photoperiod and low relative humidity, simulating the dry season, or long photoperiod and high relative humidity, simulating the wet-season. Results Mosquitoes exposed to short photoperiod exhibited larger body size and larger mesothoracic spiracle length than mosquitoes exposed to long photoperiod. Mosquitoes exposed to short photoperiod and low relative humidity exhibited greater total cuticular hydrocarbon amount than mosquitoes exposed to long photoperiod and high relative humidity. In addition, total cuticular hydrocarbon amount increased with age and was higher in mated females. Mean n-alkane retention time (a measure of cuticular hydrocarbon chain length) was lower in mosquitoes exposed to short photoperiod and low relative humidity, and increased with age. Individual cuticular hydrocarbon peaks were examined, and several cuticular hydrocarbons were identified as potential biomarkers of dry- and wet-season conditions, age, and insemination status. Conclusions Results from this study indicate that morphological and chemical changes underlie aestivation of Anopheles gambiae and may serve as biomarkers of aestivation. PMID:24970701

  10. Distribution of fish, benthic invertebrate, and algal communities in relation to physical and chemical conditions, Yakima River basin, Washington, 1990

    USGS Publications Warehouse

    Cuffney, T.F.; Meador, M.R.; Porter, S.D.; Gurtz, M.E.

    1997-01-01

    Biological investigations were conducted in the Yakima River Basin, Washington, in conjunction with a pilot study for the U.S. Geological Survey's National Water-Quality Assessment Program. Ecological surveys were conducted at 25 sites in 1990 to (1) assess water-quality conditions based on fish, benthic invertebrate, and algal communities; (2) determine the hydrologic, habitat, and chemical factors that affect the distributions of these organisms; and (3) relate physical and chemical conditions to water quality. Results of these investigations showed that land uses and other associated human activities influenced the biological characteristics of streams and rivers and overall water-quality conditions. Fish communities of headwater streams in the Cascades and Eastern Cascades ecoregions of the Yakima River Basin were primarily composed of salmonids and sculpins, with cyprinids dominating in the rest of the basin. The most common of the 33 fish taxa collected were speckled dace, rainbow trout, and Paiute sculpin. The highest number of taxa (193) was found among the inverte- brates. Insects, particularly sensitive forms such as mayflies, stoneflies, and caddisflies (EPT--Ephemeroptera, Plecoptera, and Trichoptera fauna), formed the majority of the invertebrate communities of the Cascades and Eastern Cascades ecoregions. Diatoms dominated algal communities throughout the basin; 134 algal taxa were found on submerged rocks, but other stream microhabitats were not sampled as part of the study. Sensitive red algae and diatoms were predominant in the Cascades and Eastern Cascades ecoregions, whereas the abundance of eutrophic diatoms and green algae was large in the Columbia Basin ecoregion of the Yakima River Basin. Ordination of physical, chemical, and biological site characteristics indicated that elevation was the dominant factor accounting for the distribution of biota in the Yakima River Basin; agricultural intensity and stream size were of secondary importance

  11. Laboratory insights into the chemical and kinetic evolution of several organic molecules under simulated Mars surface UV radiation conditions

    NASA Astrophysics Data System (ADS)

    Poch, O.; Kaci, S.; Stalport, F.; Szopa, C.; Coll, P.

    2014-11-01

    The search for organic carbon at the surface of Mars, as clues of past habitability or remnants of life, is a major science goal of Mars' exploration. Understanding the chemical evolution of organic molecules under current martian environmental conditions is essential to support the analyses performed in situ. What molecule can be preserved? What is the timescale of organic evolution at the surface? This paper presents the results of laboratory investigations dedicated to monitor the evolution of organic molecules when submitted to simulated Mars surface ultraviolet radiation (190-400 nm), mean temperature (218 ± 2 K) and pressure (6 ± 1 mbar) conditions. Experiments are done with the MOMIE simulation setup (for Mars Organic Molecules Irradiation and Evolution) allowing both a qualitative and quantitative characterization of the evolution the tested molecules undergo (Poch, O. et al. [2013]. Planet. Space Sci. 85, 188-197). The chemical structures of the solid products and the kinetic parameters of the photoreaction (photolysis rate, half-life and quantum efficiency of photodecomposition) are determined for glycine, urea, adenine and chrysene. Mellitic trianhydride is also studied in order to complete a previous study done with mellitic acid (Stalport, F., Coll, P., Szopa, C., Raulin, F. [2009]. Astrobiology 9, 543-549), by studying the evolution of mellitic trianhydride. The results show that solid layers of the studied molecules have half-lives of 10-103 h at the surface of Mars, when exposed directly to martian UV radiation. However, organic layers having aromatic moieties and reactive chemical groups, as adenine and mellitic acid, lead to the formation of photoresistant solid residues, probably of macromolecular nature, which could exhibit a longer photostability. Such solid organic layers are found in micrometeorites or could have been formed endogenously on Mars. Finally, the quantum efficiencies of photodecomposition at wavelengths from 200 to 250 nm

  12. The Effect of Variety and Growing Conditions on the Chemical Composition and Nutritive Value of Wheat for Broilers

    PubMed Central

    Ball, M. E. E.; Owens, B.; McCracken, K. J.

    2013-01-01

    The aim of this study was to examine the effect of variety and growing conditions of wheat on broiler performance and nutrient digestibility. One hundred and sixty-four wheat samples, collected from a wide range of different sources, locations, varieties and years, were analyzed for a range of chemical and physical parameters. Chemical and physical parameters measured included specific weight, thousand grain weight (TG), in vitro viscosity, gross energy, N, NDF, starch, total and soluble non-starch polysaccharides (NSP), lysine, threonine, amylose, hardness, rate of starch digestion and protein profiles. Ninety-four of the wheat samples were selected for inclusion in four bird trials. Birds were housed in individual wire metabolizm cages from 7 to 28 d and offered water and feed ad libitum. Dry matter intake (DMI), live weight gain (LWG) and gain:feed were determined weekly. A balance collection was carried out from 14 to 21 d for determination of apparent metabolizable energy (AME), ME:gain, DM retention, oil and NDF digestibility. At 28 d the birds were sacrificed, the contents of the jejunum removed for determination of in vivo viscosity and the contents of the ileum removed for determination of ileal DM, starch and protein digestibility. The wheat samples used in the study had wide-ranging chemical and physical parameters, leading to bird DMI, LWG, gain:feed, ME:GE, AME content and ileal starch and protein digestibility being significantly (p<0.05) affected by wheat sample. A high level of N fertilizer application to the English and NI wheat samples tended to benefit bird performance, with increases of up to 3.4, 7.2 and 3.8% in DMI, LWG and gain:feed, respectively. Fungicide application also appeared to have a positive effect on bird performance, with fungicide treated (+F) wheat increasing bird DMI, LWG and gain:feed by 6.6, 9.3 and 2.7%, over the non-fungicide treated (-F) wheats. An increase (p<0.1) of 9.3% in gain:feed was also observed at the low seed

  13. The Los Alamos National Laboratory (USA): Instituto Mexicano del Petroleo cooperative program for the ASPEN flowsheet simulator: Status report

    SciTech Connect

    Phillips, T.T.

    1987-01-01

    On June 20, 1983, the Los Alamos National Laboratory, the US Department of Energy, and the Instituto Mexicano del Petroleo (IMP) signed a Memorandum of Understanding (MOU) that established a program of cooperation between the Los Alamos National Laboratory and the IMP. This report describes the work done under Annex II of the MOU, which set up a program in the area of process simulation using the ASPEN flowsheet simulator. As a part of this program, two IMP engineers were trained at Los Alamos: one as an ASPEN system administrator and the other as an ASPEN applications engineer. After returning to Mexico, these engineers installed ASPEN on the IMP VAX computer and trained 30 other IMP engineers and scientists to use ASPEN. To date, IMP used ASPEN to simulate four major process plants. In addition, engineers from Los Alamos and IMP worked together during the summer of 1986 to develop an implementation of the UNIFAC method for predicting liquid-phase activity coefficients. The code was written and installed in ASPEN and has passed a series of initial test cases. The UNIFAC model will be released to the public domain when testing is complete. IMP has also developed and shared with Los Alamos some enhancements to a computer code that predicts physical property correlation constants for petroleum fractions. The success of the Los Alamos/IMP cooperative program for the ASPEN flowsheet simulator demonstrates that technology transfer can work in both directions. 18 refs.

  14. Applicability of DLVO Approach to Predict Trends in Iron Oxide Colloid Mobility Under Various Physical And Chemical Soil Conditions

    NASA Astrophysics Data System (ADS)

    Florian Carstens, Jannis; Bachmann, Jörg; Neuweiler, Insa

    2014-05-01

    In soil and groundwater, highly mobile iron oxide colloids can act as "shuttles" for transport of adsorbed contaminants such as heavy metals and radionuclides. Artificial iron oxide colloids are injected into polluted porous media to accelerate bacterial degradation of pollutants in the context of bioremediation purposes. The mobility of iron oxide colloids is strongly affected by the hydraulic, physical and chemical conditions of the pore space, the solid particle surface properties, the fluid phase, and the colloids themselves. Most pioneering studies focused on iron oxide colloid transport and retention in simplified model systems. The aim of this study is to investigate iron oxide colloid mobility under more complex, soil-typical conditions that have as yet only been applied for model microspheres, i.e. functionalized latex colloids. Among these conditions is the pivotal impact of organic matter, either dissolved or adsorbed onto solid particles, modifying wettability properties. Of particular importance was to determine if effective chemical surface parameters derived from contact angle and zeta potential measurements can be used as a tool to predict general tendencies for iron oxide colloid mobility in porous media. In column breakthrough experiments, goethite colloids (particle size: 200-900 nm) were percolated through quartz sand (grain size: 100-300 µm) at pH 5. The impact of a multitude of conditions on colloid mobility was determined: dissolved organic matter (DOM) concentration, ionic strength, flow velocity, flow interruption, partial saturation, and drying with subsequent re-wetting. The solid matrix consisted of either clean sand, organic matter-coated sand, goethite-coated sand, or sand hydrophobized with dichlorodimethylsilane. Additionally, contact angles and zeta potentials of the materials applied in the column experiments were measured. By means of these surface parameters, traditional DLVO interaction energies based on zeta potential as well

  15. Effect of nontronite smectite clay on the chemical evolution of several organic molecules under simulated Mars surface UV radiation conditions

    NASA Astrophysics Data System (ADS)

    Poch, Olivier; Dequaire, Tristan; Stalport, Fabien; Jaber, Maguy; Lambert, Jean-François; Szopa, Cyril; Coll, Patrice

    2015-04-01

    The search for organic carbon-containing molecules at the surface of Mars, as clues of past habitability or remnants of life, is a major scientific goal for Mars exploration. Several lines of evidence, including the detection of phyllosilicates, suggest that early Mars offered favorable conditions for long-term sustaining of water. As a consequence, we can assume that in those days, endogenous chemical processes, or even primitive life, may have produced organic matter on Mars. Moreover, exogenous delivery from small bodies or dust particles is likely to have brought fresh organic molecules to the surface of Mars up today. Organic matter is therefore expected to be present at the surface/subsurface of the planet. But the current environmental conditions at the surface - UV radiation, oxidants and energetic particles - generate physico-chemical processes that may affect organic molecules. On the other hand, on Earth, phyllosilicates are known to accumulate and preserve organic matter. But are phyllosilicates efficient at preserving organic molecules under the current environmental conditions at the surface of Mars? We have monitored the qualitative and quantitative evolutions of glycine, urea and adenine interacting with the Fe3+-smectite clay nontronite, one of the most abundant phyllosilicates present at the surface of Mars, under simulated Martian surface ultraviolet light (190-400 nm), mean temperature (218 ± 2 K) and pressure (6 ± 1 mbar) in a laboratory simulation setup. We have tested organic-rich samples which may be representative of the evaporation of a warm little pond of liquid water having concentrated organics on Mars. For each molecule, we have observed how the nontronite influences the quantum efficiency of its photodecomposition and the nature of its solid evolution products. The results reveal a pronounced photoprotective effect of nontronite on the evolution of glycine and adenine: their efficiencies of photodecomposition are reduced by a factor

  16. Mobilization and transport of metal-rich colloidal particles from mine tailings into soil under transient chemical and physical conditions.

    PubMed

    Lu, Cong; Wu, Yaoguo; Hu, Sihai; Raza, Muhammad Ali; Fu, Yilin

    2016-04-01

    Exposed mine tailing wastes with considerable heavy metals can release hazardous colloidal particles into soil under transient chemical and physical conditions. Two-layered packed columns with tailings above and soils below were established to investigate mobilization and transport of colloidal particles from metal-rich mine tailings into soil under transient infiltration ionic strength (IS: 100, 20, 2 mM) and flow rate (FR: 20.7, 41, and 62.3 mm h(-1)), with Cu and Pb as representatives of the heavy metals. Results show that the tailing particles within the colloidal size (below 2 μm) were released from the columns. A step-decrease in infiltration IS and FR enhanced, whereas a step-increase in the IS and FR restrained the release of tailing particles from the column. The effects of step-changing FR were unexpected due to the small size of the released tailing particles (220-342 nm, being not sensitive to hydrodynamic shear force), the diffusion-controlled particle release process and the relatively compact pore structure. The tailing particles present in the solution with tested IS were found negatively charged and more stable than soil particles, which provides favorable conditions for tailing particles to be transported over a long distance in the soil. The mobilization and transport of Cu and Pb from the tailings into soil were mediated by the tailing particles. Therefore, the inherent toxic tailing particles could be considerably introduced into soil under certain conditions (IS reduction or FR decrease), which may result in serious environmental pollution. PMID:26780043

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

    PubMed

    Spalding, B P; Spalding, I R

    2001-01-15

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

  18. Chemical immobilization of adult female Weddell seals with tiletamine and zolazepam: effects of age, condition and stage of lactation

    PubMed Central

    Wheatley, Kathryn E; Bradshaw, Corey JA; Harcourt, Robert G; Davis, Lloyd S; Hindell, Mark A

    2006-01-01

    Background Chemical immobilization of Weddell seals (Leptonychotes weddellii) has previously been, for the most part, problematic and this has been mainly attributed to the type of immobilizing agent used. In addition to individual sensitivity, physiological status may play an important role. We investigated the use of the intravenous administration of a 1:1 mixture of tiletamine and zolazepam (Telazol®) to immobilize adult females at different points during a physiologically demanding 5–6 week lactation period. We also compared performance between IV and IM injection of the same mixture. Results The tiletamine:zolazepam mixture administered intravenously was an effective method for immobilization with no fatalities or pronounced apnoeas in 106 procedures; however, there was a 25 % (one animal in four) mortality rate with intramuscular administration. Induction time was slightly longer for females at the end of lactation (54.9 ± 2.3 seconds) than at post-parturition (48.2 ± 2.9 seconds). In addition, the number of previous captures had a positive effect on induction time. There was no evidence for effects due to age, condition (total body lipid), stage of lactation or number of captures on recovery time. Conclusion We suggest that intravenous administration of tiletamine and zolazepam is an effective and safe immobilizing agent for female Weddell seals. Although individual traits could not explain variation in recovery time, we suggest careful monitoring of recovery times during longitudinal studies (> 2 captures). We show that physiological pressures do not substantially affect response to chemical immobilization with this mixture; however, consideration must be taken for differences that may exist for immobilization of adult males and juveniles. Nevertheless, we recommend a mass-specific dose of 0.50 – 0.65 mg/kg for future procedures with adult female Weddell seals and a starting dose of 0.50 mg/kg for other age classes and other phocid seals. PMID

  19. Influence of Variable Environmental Conditions on Presence and Concentration of Energetic Chemicals Near Soil Surface in the Vadoze Zone

    NASA Astrophysics Data System (ADS)

    Anaya, A. A.; Padilla, I. Y.

    2008-12-01

    Many explosive-related compounds (ERCs) are found near the soil-atmospheric surface in sites containing buried explosive devices, such as landmines and unexploded ordnance, detonation-residual, and munitions residues from explosive manufacturing facilities. Accurate assessment of the fate and transport processes is essential for predicting their movement to the surface, groundwater, or any other important environmental compartment. The transport processes controlling the direction and magnitude of the movement, and chemical and physical processes controlling the fate of the chemicals vary with environmental conditions. This research addresses the effect of variable rainfall, evaporation, temperature, and solar radiation on fate and transport of 2,4,6-Trinitrotoluene (TNT), 2,4-Dinitrotoluene (DNT), and other related chemicals in partially saturated soil. Experiments have been conducted in a laboratory-scale 3D SoilBed placed inside an environmental chamber equipped with rainfall and solar radiation simulators, and temperature control settings. The SoilBed was packed with a sandy soil. Experiments have been conducted by burying a TNT/DNT source, simulating a landmine, and applying different rainfall and light radiation cycles while monitoring DNT, TNT, and other related ERCs solute concentrations temporally and spatially within the SoilBed. Experiments include different source characteristics, rainfall intensities, temperatures, and radiation cycles to evaluate their effect on the detection and movement of ERC in soils in both aqueous and vapor phases. Temporal and spatial data has been analyzed comparatively and quantitatively. Comparative analysis was developed using surfer®- and voxler®-generated images and 3D visualization models applying spatial interpolation and masking methods. Single and multi-variable statistical analysis has been employed to determine the most important factors affecting the fate, transport and detection of ERC near soil

  20. Long-term Geochemical Transport Simulation to Evaluate Ambient Chemical Conditions at Horonobe URL Site, Hokkaido, Japan

    NASA Astrophysics Data System (ADS)

    Yamamoto, H.; Shimo, M.; Fujiwara, Y.; Kunimaru, T.; Xu, T.; Laaksoharju, M.

    2005-12-01

    JNC (Japan Nuclear Cycle Development Institute) has been planning an underground research laboratory (URL) in Horonobe, northern Hokkaido, Japan. In this study, long-term evolution of groundwater chemistry was simulated to evaluate ambient chemical conditions around the Horonobe URL site. The study area is about 8km by 4km and 2km deep region centered on the URL, in which the geology mainly consists of Pliocene diatomaceous argillaceous formations. Hydro-geochemical investigations using deep boreholes in about 3km by 3km area have suggested that groundwater chemistry around the site has been formed through the mixing of shallow fresh water and deep saline water. The deep groundwater has high salinity and differs from the present seawater in that it is highly reduced and has low pH, high bicarbonate and low magnesium concentration. Prior to the simulation, a computer code M3 (Laaksoharju et al. 1999) was used to model that the groundwater composition is affected by a two end-member mixing system. Next, the simulation of chemical changes during the intrusion of fresh water from land surface into deep saline water in the past 0.1 Ma was performed. A non-isothermal multiphase reactive geochemical transport simulation code TOUGHREACT (Xu and Press, 2001) was employed to solve the complex interplay of mass transport and chemical reaction in groundwater such as mineral dissolution/precipitation and ion exchange. The simulator was applied to a site-scale 3D geological structure model in which surface topography, the structures of geologic formations and a major fault were embedded. The results suggest that: 1) the spatial patterns of salinity and major constituents observed are in the site are generally consistent with a scenario of the intrusion of the surface fresh water into the deep saline water; 2) freshening of the deep saline water increases pH by cation exchange; 3) redox front migrates as oxidized water infiltrates from surface but is strongly buffered by reducing

  1. Flowsheet calculation of a combined heat and power fuel cell plant with a conceptual molten carbonate fuel cell with separate CO 2 supply

    NASA Astrophysics Data System (ADS)

    Au, S. F.; Hemmes, K.; Woudstra, N.

    A new type of MCFC with a separate CO 2 supply (improved or i-MCFC) is previously presented, which has the potential for reducing NiO cathode dissolution and system enhancement by CO 2 removal from fuel gas. This article presents the first flowsheet calculations of an i-MCFC system that utilizes the potential of reducing NiO dissolution. A submodel that simulates energy and massflows of the i-MCFC is built using standard flowsheeting components. The performance of the i-MCFC is assumed to be equal to the MCFC and differences in Nernst potentials and irreversible losses are neglected. To compare the differences in concept, a MCFC combined heat and power (CHP) system flowsheet is modified and the MCFC model substituted by the i-MCFC submodel. The overall efficiencies of both fuel cell systems are calculated using a flowsheeting program. The calculated results are compared and the differences analyzed. The overall system performance of this i-MCFC CHP system is slightly lower than the MCFC CHP reference system (about 0.1% point in average). The difference in performance is ascribed to the change in gas composition and heat capacity of the cathode gas. The change in heat capacity increases the total massflow through the i-MCFC resulting to an increase in overall auxiliary power consumption. The low CO 2 content of the cathode gas should reduce the NiO cathode dissolution to a negligible level.

  2. Effects of catalyst support and chemical vapor deposition condition on synthesis of multi-walled carbon nanocoils

    NASA Astrophysics Data System (ADS)

    Suda, Yoshiyuki; Iida, Tetsuo; Takikawa, Hirofumi; Harigai, Toru; Ue, Hitoshi; Umeda, Yoshito

    2016-02-01

    Multi-walled carbon nanocoil (MWCNC) is a carbon nanotube (CNT) with helical shape. We have synthesized MWCNCs and MWCNTs hybrid by chemical vapor deposition (CVD). MWCNCs are considered to be a potential material in nanodevices, such as electromagnetic wave absorbers and field emitters. It is very important to take into account the purity of MWCNCs. In this study, we aimed to improve the composition ratio of MWCNCs to MWCNTs by changing catalyst preparation and CVD conditions. As a catalyst, Fe2O3/zeolite was prepared by dissolving Fe2O3 fine powder and Y-type zeolite (catalyst support material) in ethanol with an Fe density of 0.5wt.% and with a zeolite density of 3.5wt.%. The catalyst-coated Si substrate was transferred immediately onto a hotplate and was heated at 80°C for 5 min. Similarly, Fe2O3/Al2O3, Co/zeolite/Al2O3, Co/zeolite, and Co/Al2O3 were prepared. The effect of the difference of the composite catalysts on synthesis of MWCNCs was considered. The CVD reactor was heated in a tubular furnace to 660-790°C in a nitrogen atmosphere at a flow rate of 1000 ml/min. Subsequently, acetylene was mixed with nitrogen at a flow rate ratio of C2H2/N2 = 0.02-0.1. The reaction was kept under these conditions for 10 min. MWCNTs and MWCNCs were well grown by the catalysts of Co/zeolite and Co/Al2O3. The composition ratio of MWCNCs to MWCNTs was increased by using a combination of zeolite and Al2O3. The highest composition ratio of MWCNCs to MWCNTs was 12%.

  3. Polymerization of amino acids under high-pressure conditions: Implication to chemical evolution on the early Earth

    NASA Astrophysics Data System (ADS)

    Kakegawa, T.; Ohara, S.; Ishiguro, T.; Abiko, H.; Nakazawa, H.

    2008-12-01

    Prebiotic polymerization of amino acids is the most fundamental reaction to promote the chemical evolution for origin of life. Polymerization of amino acids is the dehydration reaction. This questions as to if submarine hydrothermal conditions, thus hydrated enironments, were appropreate for peptide formations. Our previous experiments implied that non-aqueous and high-pressure environments (more than 20 MPa) would be suitable for polymerization of amino acids (Ohara et al., 2006). This leads to the hypothesis that the first peptides may have formed in the Hadean oceanic crustal environments, where dehydration proceeded with availability of appropriate temperatures and pressures. In the present study, experiments simulating the crustal conditions were performed with various pressures (1-175 MPa) and temperatures (100- 200 C degree) using autoclaves. Purified powders (100 mg) of alanine, glycine, valine and aspartic acid were used in the experiments without mixing water in order to examine the solid-solid reactions. The products were analyzed using HPLC and LC-MS. Results indicate that: (1) longer time is required to form peptide compared to those of previous aqueous experiments; (2) pressure has a role to limit the production of melanoidine and cyclic amino acids, which are inhibitors for elongation of peptides; (3) glycine was polymerized up to 11-mer, which was not formed in any previous experiments without catalyses; (4) valine was polymerized up to 3-mer; and (5) aspartic acid was polymerized to 4-mer, accompanied with production of other amino acids. It is noteworthy that high-pressure environments favor all examined polymerization reactions. Such situations would have happened inside of deep oceanic crusts of the early Earth.

  4. Influence of deposition conditions on mechanical properties of low-pressure chemical vapor deposited low-stress silicon nitride films

    NASA Astrophysics Data System (ADS)

    Toivola, Yvete; Thurn, Jeremy; Cook, Robert F.; Cibuzar, Greg; Roberts, Kevin

    2003-11-01

    The effect of deposition temperature, deposition pressure, or input gas ratio (SiH2Cl2:NH3) on film stress was determined for low-pressure chemical vapor deposited silicon nitride films. Wafer curvature measurements were performed for films deposited on single crystal silicon and amorphous silica wafer substrates to determine film stress σdep, biaxial modulus Ef+, and coefficient of thermal expansion αf. Apparent plane strain film modulus Ēf' and hardness H were measured using depth-sensing indentation. Ellipsometry was used to measure film thickness tf and refractive index n. Infrared spectroscopy, x-ray photoelectron spectroscopy (XPS), forward recoil energy spectroscopy (FReS), and Rutherford backscattering spectroscopy (RBS) experiments were performed to determine film composition. Although film deposition stress varied from -135 MPa (compressive) to 235 MPa (tensile) Ef+, Ēf', H, and αf remained nearly constant. Infrared spectroscopy resolved only Si-N species for all films, and results from FReS on three films confirmed that the hydrogen content was negligible. RBS and XPS indicated that Si/N increased with increased compressive σdep. Ellipsometry and RBS indicated that all films were silicon-rich, to a greater extent with increased compressive σdep. As RBS indicated that atomic density decreased with increased compressive deposition stress, it was concluded that the deposition conditions changed both thermal and intrinsic deposition stress for all films. In particular, intrinsic stress was tensile, and became increasingly tensile for increased Si/N and decreased atomic density. Assuming thermal stress was similar for all films examined here, the intrinsic stress must have varied from changes dependent on the deposition conditions.

  5. Chemical composition and anticancer activity of essential oils of Mediterranean sage (Salvia officinalis L.) grown in different environmental conditions.

    PubMed

    Russo, Alessandra; Formisano, Carmen; Rigano, Daniela; Senatore, Felice; Delfine, Sebastiano; Cardile, Venera; Rosselli, Sergio; Bruno, Maurizio

    2013-05-01

    Salvia officinalis L. can be found worldwide and its leaves are commonly used as ingredient in food industry. Sage essential oil is applied in the treatment of a range of diseases and has been shown to possess different biological activities. The objectives of our research were to study the effects of environment on crop, chemical composition and anticancer activity on S. officinalis essential oil. Sage was cultivated at eighteen experimental sites in south-central Italy (Molise) in different growing environments. The essential oils (S1-S18), extracted by hydrodistillation, were analyzed by GC and CG/MS. Results show that the main components were α-thujone, camphor, borneol, γ-muurolene and sclareol for all the samples, but the percentages of these compounds varied depending on environmental factors such as altitude, water availability and pedo-climatic conditions. The growth-inhibitory and proapoptotic effects of the eighteen sage essential oils were evaluated in three human melanoma cell lines, A375, M14, and A2058. PMID:23291326

  6. Thermal response of intravascular and rectal tissue to temperature changes and chemical conditions in the rumen of sheep

    PubMed Central

    Mendel, V. E.; Raghavan, G. V.

    1966-01-01

    1. Experiments were conducted with two wether sheep which were fitted with rumen cannulae and chronically implanted intravascular thermocouples. An attempt was made to study the thermal response of intravascular and rectal tissue to temperature changes and chemical conditions in the rumen. 2. When ice or hot water were placed in the rumen there was an immediate fall or rise in the intravascular temperature accompanied by a similar change in rectal temperature. The intravascular temperatures returned to their precooling or preheating level of 40° C within 130 min, the rectal temperatures required 6-8 hr to return to their pretreatment values. 3. When 0·5 M acetic acid was infused into the rumen there was a marked rise in the intravascular temperature, over and above the diurnal rhythm but not in rectal temperatures. Infusion of mixtures of acetic plus propionic or acetic plus n-butyric acids caused an intravascular temperature rise on feeding within the range of the diurnal pattern. In fasted animals, infusions of volatile fatty acids resulted in no rise in intravascular temperature. PMID:5937414

  7. Impact of chemical and meteorological boundary and initial conditions on air quality modeling: WRF-Chem sensitivity evaluation for a European domain

    NASA Astrophysics Data System (ADS)

    Ritter, Mathias; Müller, Mathias D.; Jorba, Oriol; Parlow, Eberhard; Liu, L.-J. Sally

    2013-01-01

    This study evaluates the impact of different chemical and meteorological boundary and initial conditions on the state-of-the-art Weather Research and Forecasting (WRF) model with its chemistry extension (WRF-Chem). The evaluation is done for July 2005 with 50 km horizontal resolution. The effect of monthly mean chemical boundary conditions derived from the chemical transport model LMDZ-INCA on WRF-Chem is evaluated against the effect of the preset idealized profiles. Likewise, the impact of different meteorological initial and boundary conditions (GFS and Reanalysis II) on the model is evaluated. Pearson correlation coefficient between these different runs range from 0.96 to 1.00. Exceptions exists for chemical boundary conditions on ozone and for meteorological boundary conditions on PM10, where coefficients of 0.90 were obtained. Best results were achieved with boundary and initial conditions from LMDZ-INCA and GFS. Overall, the European simulations show encouraging results for observed air pollutant, with ozone being the most and PM10 being the least satisfying.

  8. Mineral chemical compositions of late Cretaceous volcanic rocks in the Giresun area, NE Turkey: Implications for the crystallization conditions

    NASA Astrophysics Data System (ADS)

    Oǧuz, Simge; Aydin, Faruk; Uysal, İbrahim; Şen, Cüneyt

    2016-04-01

    This contribution contains phenocryst assemblages and mineral chemical data of late Cretaceous volcanic (LCV) rocks from the south of Görele and Tirebolu areas (Giresun, NE Turkey) in order to investigate their crystallization conditions. The LCV rocks in the study area occur in two different periods (Coniasiyen-Early Santonian and Early-Middle Campanian), which generally consist of alternation of mafic-intermediate (basaltic to andesitic) and felsic rock series (dacitic and rhyolitic) within each period. The basaltic and andesitic rocks in both periods generally exhibit porphyritic to hyalo-microlitic porphyritic texture, and contain phenocrysts of plagioclase and pyroxene, whereas the dacitic and rhyolitic rocks of the volcanic sequence usually show a vitrophyric texture with predominant plagioclase, K-feldspar, quartz and lesser amphibole-biotite phenocrysts. Zoned plagioclase crystals of the mafic and felsic rocks in different volcanic periods are basically different in composition. The compositions of plagioclase in the first-stage mafic rocks range from An52 to An78 whereas those of plagioclase from the first-stage felsic rocks have lower An content varying from An38 to An50. Rim to core profile for the zoned plagioclase of the first-stage mafic rocks show quite abrupt and notable compositional variations whereas that of the first-stage felsic rocks show slight compositional variation, although some of the grains may display reverse zoning. On the other hand, although no zoned plagioclase phenocryst observed in the second-stage mafic rocks, the compositions of microlitic plagioclase show wide range of compositional variation (An45‑80). The compositions of zoned plagioclase in the second-stage felsic rocks are more calcic (An65‑81) than those of the first-stage felsic rocks, and their rim to core profile display considerable oscillatory zoning. The compositions of pyroxenes in the first- and second-stage mafic-intermediate rocks vary over a wide range

  9. Caustic-Side Solvent Extraction Chemical and Physical Properties Progress in FY 2000 and FY 2001.

    SciTech Connect

    Moyer, BA

    2002-04-17

    The purpose of this work was to provide chemical- and physical-property data addressing the technical risks of the Caustic-Side Solvent Extraction (CSSX) process as applied specifically to the removal of cesium from alkaline high-level salt waste stored at the US Department of Energy Savannah River Site. As part of the overall Salt Processing Project, this effort supported decision-making in regards to selecting a preferred technology among three alternatives: (1) CSSX, (2) nonelutable ion-exchange with an inorganic silicotitanate material and (3) precipitation with tetraphenylborate. High risks, innate to CSSX, that needed specific attention included: (1) chemical stability of the solvent matrix, (2) radiolytic stability of the solvent matrix, (3) proof-of-concept performance of the proposed process flowsheet with simulated waste, and (4) performance of the CSSX flowsheet with actual SRS high-level waste. This body of work directly addressed the chemical-stability risk and additionally provided supporting information that served to plan, carry out, and evaluate experiments conducted by other CSSX investigators addressing the other high risks. Information on cesium distribution in extraction, scrubbing, and stripping served as input for flowsheet design, provided a baseline for evaluating solvent performance under numerous stresses, and contributed to a broad understanding of the effects of expected process variables. In parallel, other measurements were directed toward learning how other system components distribute in the flowsheet. Such components include the solvent components themselves, constituents of the waste, and solvent-degradation products. Upon understanding which components influence flowsheet performance, it was then possible to address in a rational fashion how to clean up the solvent and maintain its stable function.

  10. Norepinephrine stimulates progesterone production in highly estrogenic bovine granulosa cells cultured under serum-free, chemically defined conditions

    PubMed Central

    2012-01-01

    Background Since noradrenergic innervation was described in the ovarian follicle, the actions of the intraovarian catecholaminergic system have been the focus of a variety of studies. We aimed to determine the gonadotropin-independent effects of the catecholamine norepinephrine (NE) in the steroid hormone profile of a serum-free granulosa cell (GC) culture system in the context of follicular development and dominance. Methods Primary bovine GCs were cultivated in a serum-free, chemically defined culture system supplemented with 0.1% polyvinyl alcohol. The culture features were assessed by hormone measurements and ultrastructural characteristics of GCs. Results GCs produced increasing amounts of estradiol and pregnenolone for 144h and maintained ultrastructural features of healthy steroidogenic cells. Progesterone production was also detected, although it significantly increased only after 96h of culture. There was a highly significant positive correlation between estradiol and pregnenolone production in high E2-producing cultures. The effects of NE were further evaluated in a dose–response study. The highest tested concentration of NE (10 (−7) M) resulted in a significant increase in progesterone production, but not in estradiol or pregnenolone production. The specificity of NE effects on progesterone productio n was further investigated by incubating GCs with propranolol (10 (−8) M), a non-selective beta-adrenergic antagonist. Conclusions The present culture system represents a robust model to study the impact of intrafollicular factors, such as catecholamines, in ovarian steroidogenesis and follicular development. The results of noradrenergic effects in the steroidogenesis of GC have implications on physiological follicular fate and on certain pathological ovarian conditions such as cyst formation and anovulation. PMID:23171052

  11. PLD deposition of tungsten carbide contact for diamond photodiodes. Influence of process conditions on electronic and chemical aspects

    NASA Astrophysics Data System (ADS)

    Cappelli, E.; Bellucci, A.; Orlando, S.; Trucchi, D. M.; Mezzi, A.; Valentini, V.

    2013-08-01

    Tungsten carbide, WC, contacts behave as very reliable Schottky contacts for opto-electronic diamond devices. Diamond is characterized by superior properties in high-power, high frequency and high-temperature applications, provided that thermally stable electrode contacts will be realized. Ohmic contacts can be easily achieved by using carbide-forming metals, while is difficult to get stable Schottky contacts at elevated temperatures, due to the interface reaction and/or inter-diffusion between metals and diamond. Novel type of contacts, made of tungsten carbide, WC, seem to be the best solution, for their excellent thermal stability, high melting point, oxidation and radiation resistance and good electrical conductivity. Our research was aimed at using pulsed laser deposition for WC thin film deposition, optimizing experimental parameters, to obtain a final device characterized by excellent electronic properties, as a detector for radiation in deep UV or as X-ray dosimeter. We deposited our films by laser ablation from a target of pure WC, using different reaction conditions (i.e., substrate heating, vacuum or reactive atmosphere (CH4/Ar), RF plasma activated), to optimize both the stoichiometry of the film and its structure. Trying to obtain a material with the best electronic response, we used also two sources of laser radiation for target ablation, i.e., nano-second pulsed excimer laser ArF, and ultra-short fs Ti:Sapphire laser. The structure and chemical aspects have been evaluated by Raman and X-ray photoelectron spectroscopy (XPS), while the dosimeter photodiode response has been tested by the I-V measurements, under soft X-ray irradiation.

  12. CHEMICAL TRANSFORMATIONS USING NON-TRADITIONAL APPROACHES: MICROWAVE-ASSISTED GREENER SYNTHESES IN AQUEOUS MEDIA OR UNDER SOLVENT-FREE CONDITIONS

    EPA Science Inventory

    Microwave (MW) irradiation in conjunction with water as reaction media has proven to be a 'greener' chemical approach for expeditious N-alkylation reactions of amines and hydrazines wherein the reactions under mildly basic conditions afford tertiary amines and double N<...

  13. Volatile chemical spoilage indexes of raw Atlantic salmon (salmo salar)stored under aerobic condition in relation to microbiological and sensory shelf lives

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The purpose of this investigation was to identify and quantify the volatile chemical spoilage indexes (CSIs) for raw Atlantic salmon (Salmo salar) fillets stored under aerobic storage conditions at 4, 10 and 21 degrees C in relation to the determined microbial and sensory shelf lives. The volatile o...

  14. DWPF SB6 INITIAL CPC FLOWSHEET TESTING SB6-1 TO SB6-4L TESTS OF SB6-A AND SB6-B SIMULANTS

    SciTech Connect

    Lambert, D.; Pickenheim, B.; Best, D.

    2009-09-09

    The Defense Waste Processing Facility (DWPF) will transition from Sludge Batch 5 (SB5) processing to Sludge Batch 6 (SB6) processing in late fiscal year 2010. Tests were conducted using non-radioactive simulants of the expected SB6 composition to determine the impact of varying the acid stoichiometry during the Sludge Receipt and Adjustment Tank (SRAT) and Slurry Mix Evaporator (SME) processes. The work was conducted to meet the Technical Task Request (TTR) HLW/DWPF/TTR-2008-0043, Rev.0 and followed the guidelines of a Task Technical and Quality Assurance Plan (TT&QAP). The flowsheet studies are performed to evaluate the potential chemical processing issues, hydrogen generation rates, and process slurry rheological properties as a function of acid stoichiometry. These studies were conducted with the estimated SB6 composition at the time of the study. This composition assumed a blend of 101,085 kg of Tank 4 insoluble solids and 179,000 kg of Tank 12 insoluble solids. The current plans are to subject Tank 12 sludge to aluminum dissolution. Liquid Waste Operations assumed that 75% of the aluminum would be dissolved during this process. After dissolution and blending of Tank 4 sludge slurry, plans included washing the contents of Tank 51 to {approx}1M Na. After the completion of washing, the plan assumes that 40 inches on Tank 40 slurry would remain for blending with the qualified SB6 material. There are several parameters that are noteworthy concerning SB6 sludge: (1) This is the second batch DWPF will be processing that contains sludge that has had a significant fraction of aluminum removed through aluminum dissolution; (2) The sludge is high in mercury, but the projected concentration is lower than SB5; (3) The sludge is high in noble metals, but the projected concentrations are lower than SB5; and(4) The sludge is high in U and Pu - components that are not added in sludge simulants. Six DWPF process simulations were completed in 4-L laboratory-scale equipment using

  15. Snap-frozen brain tissue sections stored with desiccant at ambient laboratory conditions without chemical fixation are resistant to degradation for a minimum of 6 months.

    PubMed

    Sadler, Theodore R; Khodavirdi, Ani C; Hinton, David R; Holschneider, Daniel P

    2009-03-01

    Cryosectioned tissues from snap-frozen samples offer the advantage of preserving proteins at the cellular and subcellular levels and maintaining overall cell integrity in the tissue of interest without the use of chemical fixatives. To prevent specific or nonspecific degradation of proteins by autolytic and/or proteolytic processes, it is common practice to immediately store frozen tissue sections obtained from a cryostat under cryogenic conditions, for example -80 degrees C. Our laboratory recently challenged this widely held belief by extracting proteins from brain tissue samples that were archived for 1 day, 1 week, 1 month, and 6 months at various storage conditions (frozen, ambient, or desiccated) without the use of chemical fixatives. Our results from immunofluorescent stains, immunoperoxidase stains, silver stains, and Western blot analyses demonstrated that snap-frozen, heat-dried tissue sections stored and desiccated at ambient laboratory conditions are comparable to frozen samples stored up to 6 months. PMID:19521279

  16. PHYSICAL, CHEMICAL AND BIOLOGICAL CONDITIONS OF THE SAGAVANIRKTOK RIVER AND NEARBY CONTROL STREAMS, SHAVIOVIK AND CANNING RIVERS

    EPA Science Inventory

    Biological, physical and chemical data were collected from 28 stations on the Sagavanirktok River and five of its tributaries, the Canning River, Shaviovik River, two tundra lakes and Galbraith Lake. These stations are located on the North Slope of Alaska and in the area impacted...

  17. Experimental paradigm for in-lab proxy aquatic studies under conditions of static, non flow through chemical exposures

    EPA Science Inventory

    Endocrine disrupting chemicals (EDCs) such as 17α ethynylestradiol (EE2), 17β estradiol (E2), estrone (E1) and para-nonylphenol (NP) have been measured in wastewater treatment plant effluents, surface waters, sediments and sludge, and have been shown to induce liver-sp...

  18. Unlocking the Sporicidal Potential of Ethanol: Induced Sporicidal Activity of Ethanol against Clostridium difficile and Bacillus Spores under Altered Physical and Chemical Conditions

    PubMed Central

    Nerandzic, Michelle M.; Sunkesula, Venkata C. K.; C., Thriveen Sankar; Setlow, Peter; Donskey, Curtis J.

    2015-01-01

    Background Due to their efficacy and convenience, alcohol-based hand sanitizers have been widely adopted as the primary method of hand hygiene in healthcare settings. However, alcohols lack activity against bacterial spores produced by pathogens such as Clostridium difficile and Bacillus anthracis. We hypothesized that sporicidal activity could be induced in alcohols through alteration of physical or chemical conditions that have been shown to degrade or allow penetration of spore coats. Principal Findings Acidification, alkalinization, and heating of ethanol induced rapid sporicidal activity against C. difficile, and to a lesser extent Bacillus thuringiensis and Bacillus subtilis. The sporicidal activity of acidified ethanol was enhanced by increasing ionic strength and mild elevations in temperature. On skin, sporicidal ethanol formulations were as effective as soap and water hand washing in reducing levels of C. difficile spores. Conclusions These findings demonstrate that novel ethanol-based sporicidal hand hygiene formulations can be developed through alteration of physical and chemical conditions. PMID:26177038

  19. Chemical composition and bioactive compounds of garlic (Allium sativum L.) as affected by pre- and post-harvest conditions: A review.

    PubMed

    Martins, Natália; Petropoulos, Spyridon; Ferreira, Isabel C F R

    2016-11-15

    Garlic (Allium sativum L.) is considered one of the twenty most important vegetables, with various uses throughout the world, either as a raw vegetable for culinary purposes, or as an ingredient of traditional and modern medicine. Furthermore, it has also been proposed as one of the richest sources of total phenolic compounds, among the usually consumed vegetables, and has been highly ranked regarding its contribution of phenolic compounds to human diet. This review aims to examine all the aspects related with garlic chemical composition and quality, focusing on its bioactive properties. A particular emphasis is given on the organosulfur compounds content, since they highly contribute to the effective bioactive properties of garlic, including its derived products. The important effects of pre-harvest (genotype and various cultivation practices) and post-harvest conditions (storage conditions and processing treatments) on chemical composition and, consequently, bioactive potency of garlic are also discussed. PMID:27283605

  20. Influence of Chemical Composition on Rupture Properties at 1200 Degrees F. of Forged Chromium-Cobalt-Nickel-Iron Base Alloys in Solution-Treated and Aged Condition

    NASA Technical Reports Server (NTRS)

    Reynolds, E E; Freeman, J W; White, A E

    1951-01-01

    The influence of systematic variations of chemical composition on rupture properties at 1200 degrees F. was determined for 62 modifications of a basic alloy containing 20 percent chromium, 20 percent nickel, 20 percent cobalt, 3 percent molybdenum, 2 percent tungsten, 1 percent columbium, 0.15 percent carbon, 1.7 percent manganese, 0.5 percent silicon, 0.12 percent nitrogen and the balance iron. These modifications included individual variations of each of 10 elements present and simultaneous variations of molybdenum, tungsten, and columbium. Laboratory induction furnace heats were hot-forged to round bar stock, solution-treated at 2200 degrees F., and aged at 1400 degrees F. The melting and fabrication conditions were carefully controlled in order to minimize all variable effects on properties except chemical composition. Information is presented which indicates that melting and hot-working conditions play an important role in high-temperature properties of alloys of the type investigated.

  1. Evaluating crude oil chemical dispersion efficacy in a flow-through wave tank under regular non-breaking wave and breaking wave conditions.

    PubMed

    Li, Zhengkai; Lee, Kenneth; King, Thomas; Boufadel, Michel C; Venosa, Albert D

    2009-05-01

    Testing dispersant effectiveness under conditions similar to that of the open environment is required for improvements in operational procedures and the formulation of regulatory guidelines. To this end, a novel wave tank facility was fabricated to study the dispersion of crude oil under regular non-breaking and irregular breaking wave conditions. This wave tank facility was designed for operation in a flow-through mode to simulate both wave- and current-driven hydrodynamic conditions. We report here an evaluation of the effectiveness of chemical dispersants (Corexit EC9500A and SPC 1000) on two crude oils (Medium South American [MESA] and Alaska North Slope [ANS]) under two different wave conditions (regular non-breaking and plunging breaking waves) in this wave tank. The dispersant effectiveness was assessed by measuring the water column oil concentration and dispersed oil droplet size distribution. In the absence of dispersants, nearly 8-19% of the test crude oils were dispersed and diluted under regular wave and breaking wave conditions. In the presence of dispersants, about 21-36% of the crude oils were dispersed and diluted under regular waves, and 42-62% under breaking waves. Consistently, physical dispersion under regular waves produced large oil droplets (volumetric mean diameter or VMD > or = 300 microm), whereas chemical dispersion under breaking waves created small droplets (VMD < or = 50 microm). The data can provide useful information for developing better operational guidelines for dispersant use and improved predictive models on dispersant effectiveness in the field. PMID:19157465

  2. Influence of Chemical Composition and Heat Treatment Condition on Impact Toughness of 15Cr Ferritic Creep Resistant Steel

    NASA Astrophysics Data System (ADS)

    Toda, Yoshiaki; Tohyama, Hideaki; Kushima, Hideaki; Kimura, Kazuhiro; Abe, Fujio

    Influences of chemical compositions, heat treatment and microstructure on impact toughness of 15Cr ferritic steel have been investigated. Charpy impact values of the furnace cooled steels were lower than 15J/cm2 at room temperature independent of chemical compositions. Drastic improvement in impact toughness has been attained by controlling the carbon and nitrogen contents, by the addition of nickel and by the increase in cooling rate after annealing. However, the effect of nickel on impact toughness strongly depends on carbon and nitrogen contents. Improvement in impact toughness of the 15Cr ferritic steel has not been explained by individual microstructural factors of grain size, distribution of precipitates, volume fraction of martensitic phase. It has been supposed that the increase in Charpy impact toughness of the 15Cr ferritic steel was attained by improvement in toughness of ferrite matrix itself.

  3. Influence of chemical extraction conditions on the physicochemical and functional properties of polysaccharide gum from durian (Durio zibethinus) seed.

    PubMed

    Mirhosseini, Hamed; Amid, Bahareh Tabatabaee

    2012-01-01

    Durian seed is an agricultural biomass waste of durian fruit. It can be a natural plant source of non-starch polysaccharide gum with potential functional properties. The main goal of the present study was to investigate the effect of chemical extraction variables (i.e., the decolouring time, soaking temperature and soaking time) on the physicochemical properties of durian seed gum. The physicochemical and functional properties of chemically-extracted durian seed gum were assessed by determining the particle size and distribution, solubility and the water- and oil-holding capacity (WHC and OHC). The present work revealed that the soaking time should be considered as the most critical extraction variable affecting the physicochemical properties of crude durian seed gum. PMID:22643356

  4. Hadron multiplicities and chemical freeze-out conditions in proton-proton and nucleus-nucleus collisions

    NASA Astrophysics Data System (ADS)

    Vovchenko, V.; Begun, V. V.; Gorenstein, M. I.

    2016-06-01

    New results of the NA61/SHINE Collaboration at the CERN SPS on mean hadron multiplicities in proton-proton (p+p) interactions are analyzed within the transport models and the hadron resonance gas (HRG) statistical model. The chemical freeze-out parameters in p+p interactions and central Pb+Pb (or Au+Au) collisions are found and compared with each other in the range of the center-of-mass energy of the nucleon pair √{sN N}=3.2 -17.3 GeV. The canonical ensemble formulation of the HRG model is used to describe mean hadron multiplicities in p+p interactions and the grand canonical ensemble in central Pb+Pb and Au+Au collisions. The chemical freeze-out temperatures in p+p interactions are found to be larger than the corresponding temperatures in central nucleus-nucleus collisions.

  5. Surface chemical characteristics of coal fly ash particles after interaction with seawater under natural deep sea conditions

    SciTech Connect

    Brami, Y.; Shemesh, A.; Cohen, H.; Herut, B.

    1999-01-15

    The surface chemical characteristics of coal fly ash (CFA) before and after interaction with Mediterranean deep seawater was studied by X-ray photoelectron spectroscopy (XPS). Significantly lower values of Si, Ca, and S and higher values of Mg and Cl were found in the retrieved CFA as compared to fresh CFA. It is suggested that hydrolysis of the oxide matrixes results in an alkaline environment which rapidly leads to several chemical reactions. The two most important are (a) dissolution of the amorphous silicate and the calcium phases and (b) precipitation of Mg(OH){sub 2}-brucite. A depth profile of the retrieved CFA was measured by both line-shape analysis of the XPS spectra and by consecutive cycle of sputtering. The thickness of the brucite layer is estimated to be 1.3 nm.

  6. Morphological and chemical stability of silicon nanostructures and their molecular overlayers under physiological conditions: towards long-term implantable nanoelectronic biosensors

    PubMed Central

    2014-01-01

    Background The detection of biological and chemical species is of key importance to numerous areas of medical and life sciences. Therefore, a great interest exists in developing new, rapid, miniature, biocompatible and highly sensitive sensors, capable to operate under physiological conditions and displaying long-term stabilities (e.g. in-body implantable sensors). Silicon nanostructures, nanowires and nanotubes, have been extensively explored as building blocks for the creation of improved electrical biosensing devices, by virtue of their remarkably high surface-to-volume ratios, and have shown exceptional sensitivity for the real time label-free detection of molecular species adsorbed on their surfaces, down to the sensitivity of single molecules. Yet, till this date, almost no rigorous studies have been performed on the temporal morphological stability of these nanostructures, and their resulting electrical devices, under physiological conditions (e.g. serum, blood), as well as on the chemical stability of the molecular recognition over-layers covering these structures. Results Here, we present systematic time-resolved results on the morphological stability of bare Si nanowire building blocks, as well on the chemical stability of siloxane-based molecular over-layers, under physiological conditions. Furthermore, in order to overcome the observed short-term morpho-chemical instabilities, we present on the chemical passivation of the Si nanostructures by thin metal oxide nanoshells, in the range of 3–10 nm. The thickness of the metal oxide layer influences on the resulting electrical sensitivity of the fabricated FETs (field effect transistors), with an optimum thickness of 3–4 nm. Conclusions The core-shell structures display remarkable long-term morphological stability, preventing both, the chemical hydrolytic dissolution of the silicon under-structure and the concomitant loss of the siloxane-based chemical over-layers, for periods of at least several

  7. STATUS OF CHEMICAL CLEANING OF WASTE TANKS AT THE SAVANNAH RIVER SITE F TANK FARM CLOSURE PROJECT - 9114

    SciTech Connect

    Thaxton, D; Geoff Clendenen, G; Willie Gordon, W; Samuel Fink, S; Michael Poirier, M

    2008-12-31

    Chemical Cleaning is currently in progress for Tanks 5 and 6 at the Savannah River Site. The Chemical Cleaning process is being utilized to remove the residual waste heel remaining after completion of Mechanical Sludge Removal. This work is required to prepare the tanks for closure. Tanks 5 and 6 are 1950s vintage carbon steel waste tanks that do not meet current containment standards. These tanks are 22.9 meters (75 feet) in diameter, 7.5 meters (24.5 feet) in height, and have a capacity of 2.84E+6 liters (750,000 gallons). Chemical Cleaning adds 8 wt % oxalic acid to the carbon steel tank to dissolve the remaining sludge heel. The resulting acidic waste solution is transferred to Tank 7 where it is pH adjusted to minimize corrosion of the carbon steel tank. The Chemical Cleaning flowsheet includes multiple strikes of acid in each tank. Acid is delivered by tanker truck and is added to the tanks through a hose assembly connected to a pipe penetration through the tank top. The flowsheet also includes spray washing with acid and water. This paper includes an overview of the configuration required for Chemical Cleaning, the planned flowsheet, and an overview of technical concerns associated with the process. In addition, the current status of the Chemical Cleaning process in Tanks 5 and 6, lessons learned from the execution of the process, and the path forward for completion of cleaning in Tanks 5 and 6 will also be discussed.

  8. Chemical sensor

    NASA Technical Reports Server (NTRS)

    Rauh, R. David (Inventor)

    1990-01-01

    A sensor for detecting a chemical substance includes an insertion element having a structure which enables insertion of the chemical substance with a resulting change in the bulk electrical characteristics of the insertion element under conditions sufficient to permit effective insertion; the change in the bulk electrical characteristics of the insertion element is detected as an indication of the presence of the chemical substance.

  9. Physical vs. Chemical Weathering Controls of Soils' Capacity to Store Carbon: Hillslope Transects under Different Climatic Conditions

    NASA Astrophysics Data System (ADS)

    Yoo, K.; Wackett, A.; Amundson, R.; Heimsath, A. M.

    2015-12-01

    Soil C storage is balanced by photosynthetic production and microbial decomposition of organic matter (OM). Recently, this view has been expanded to account for the effects of physical erosion of OM in determining soil C storage. In parallel, the focus on OM quality as a primary determinant of C turnover has shifted to OM-mineral interactions. These recent advances necessitates our ability to discern how physical erosion, which controls the production, breakdown, and removal of colluvial soils, and chemical weathering, which generates secondary phyllosilicate and iron oxides, independently and collaboratively affect soils' capacity to store C. Here we present soil organic C contents and storages as a function of soil properties that are controlled by physical vs. chemical weathering processes. The study site includes two hillslopes under different climates in SW Australia. The wetter site has continuous canopy of eucalyptus, while the drier site is covered by grasses with scattered eucalyptus overstorey. The two hillslope transects share similar granodiorite parent materials and denudation rates. Bioturbation-driven soil creep appears equally effective at both sites. In eroding areas, chemical weathering has created greater mineral surface area in the soils of wetter site, while physical soil production and erosion resulted in forming the eroding soils of similar thicknesses at both sites. In the drier site, however, vegetation density varies significantly with topography-dependent soil moisture, which appears to have resulted in a soil toposequence where impacts of localized overland-flow erosion is evident through soil mineral surface area, texture, and C contents. These soil properties, in contrast, are largely homogeneous across the wetter hillslope transect presumably because of the lack of localized overland-flow erosion. As a result, at the depositional areas, the drier site exhibits greater or similar soil C storages, which sharply contrasts with the

  10. 3D mapping of chemical distribution from melting at lower mantle conditions in the laser-heated diamond anvil cell

    NASA Astrophysics Data System (ADS)

    Dorfman, S. M.; Nabiei, F.; Cantoni, M.; Badro, J.; Gaal, R.; Gillet, P.

    2014-12-01

    The laser-heated diamond anvil cell is a unique tool for subjecting materials to pressures over few hundreds of GPa and temperatures of thousands of Kelvins which enables us to experimentally simulate the inaccessible interiors of planets. However, small sample size, laser profile and thermally conductive diamonds cause temperature gradients of 1000s K over a few microns which also affects chemical and structural distribution of phases in the sample. We have examined samples of San Carlos olivine (Mg,Fe)2SiO3 powder melted in the diamond anvil cell by double-sided and single-sided laser heating for 3-6 minutes to ~3000 K at 35-37 GPa. Moreover, MgO is used as an insulating media in one of the sample. Recovered samples were analyzed by a combination of focused ion beam (FIB) and scanning electron microscope (SEM) equipped with energy dispersive x-ray (EDX) detector. Images and chemical maps were acquired for ~300 slices with ~70 nm depth from each sample, comprising about half of the heated zone. Detailed chemical and structural analysis by transmission electron microscopy (TEM) of lamellas prepared from the remaining section of the samples will also be presented. In all samples the heated zone included (Mg,Fe)SiO3 perovskite-structured bridgmanite (PV) phase and two (Mg, Fe)O phases, one of which, magnesiowüstite (MW), is richer in iron than the other one, ferropericlase (FP). In double-side heated samples we observe a Fe-rich quenched melt core surrounded by MW phase. Our results show that with increasing heating time, Fe migrates to the molten center of the sample. In the single-side heated sample, the Fe-rich MW phase is concentrated in the center of heated zone. In all samples a FP crust was observed around the heated zone. This crust, however, is broken in the upper part (colder part) of the single-side heated sample due the high asymmetrical temperature gradient within the sample. The results confirm the importance of double-side heating and insulating media

  11. Crystal Engineering of an nbo Topology Metal-Organic Framework for Chemical Fixation of CO₂ under Ambient Conditions

    SciTech Connect

    Gao, Wen-Yang; Chen, Yao; Niu, Youhong; Williams, Kia; Cash, Lindsay; Perez, Pastor J.; Wojtas, Lukasz; Cai, Jianfeng; Chen, Yu-Sheng; Ma, Shengqian

    2015-02-20

    Crystal engineering of the nbo metal–organic framework (MOF) platform MOF-505 with a custom-designed azamacrocycle ligand (1,4,7,10-tetrazazcyclododecane-N,N',N'',N'''-tetra-p-methylbenzoic acid) leads to a high density of well-oriented Lewis active sites within the cuboctahedral cage in MMCF-2, [Cu₂(Cu-tactmb)(H₂O)₃(NO₃)₂]. This MOF demonstrates high catalytic activity for the chemical fixation of CO₂ into cyclic carbonates at room temperature under 1 atm pressure.

  12. Phytoplankton and physical-chemical conditions in selected rivers and the coastal zone of Lake Michigan, 1972

    SciTech Connect

    Schelske, C.L.; Feldt, L.E.; Simmons, M.S.

    1980-01-01

    A very large data set was obtained on the nearshore environment of Lake Michigan during 1972. The data set is probably unique in that samples were collected and analyzed for a number of physical-chemical parameters and for phytoplankton standing crop and species composition. Phytoplankton identified during the study totaled 431 taxa of which 306 were diatoms, which serves to illustrate the magnitude of available data. Results are presented for eleven different transects sampled in April and for three of these transects which were sampled in September. In addition, transects for the St. Joseph, Kalamazoo, and Grand Rivers were sampled four or five times and each of these rivers were sampled from seven to eleven times in July. Data collected with depth presented in this report include water temperature. Secchi disc transparency, pH, specific conductance, dissolved reactive silica, nitrate nitrogen, and total phosphorus as physical-chemical variables. On transects samples with depth were obtained at stations 0, .2, .8, 1.6, 3.2, 6.4, 13, 26, and 52 km from shore, although the stations from 13 to 52 km were not sampled on every transect. Data related to phytoplankton include species composition and abundance, species diversity, chlorophyll a, and rates of carbon fixation. All these data were obtained only at 2 meters.

  13. Adaptive plasticity of Laguncularia racemosa in response to different environmental conditions: integrating chemical and biological data by chemometrics.

    PubMed

    da Souza, Iara; Bonomo, Marina Marques; Morozesk, Mariana; Rocha, Lívia Dorsch; Duarte, Ian Drumond; Furlan, Larissa Maria; Arrivabene, Hiulana Pereira; Monferrán, Magdalena Victoria; Matsumoto, Silvia Tamie; Milanez, Camilla Rozindo Dias; Wunderlin, Daniel Alberto; Fernandes, Marisa Narciso

    2014-04-01

    Mangroves are dynamic environments under constant influence of anthropic contaminants. The correlation between environmental contamination levels and possible changes in the morphology of plants, evaluated by multivariate statistics helps to highlight matching between these variables. This study aimed to evaluate the uptake and translocation of metals and metalloids in roots and leaves as well as the changes induced in both anatomy and histochemistry of roots of Laguncularia racemosa inhabiting two estuaries of Espírito Santo (Brazil) with different pollution degrees. The analysis of 14 elements in interstitial water, sediments and plants followed by multivariate statistics, allowed the differentiation of studied sites, showing good match between levels of elements in the environment with the corresponding in plants. L. racemosa showed variations in their root anatomy in different collection areas, with highest values of cortex/vascular cylinder ratio, periderm thickness and air gap area in Vitória Bay, the most polluted sampling area. These three parameters were also important to differentiate the mangrove areas by linear discriminant analysis. The development stage of aerenchyma in roots reflected the oxygen availability in the water, being found a negative correlation between these variables. The combined use of chemical and biological analyses responded quite well to different pollution scenarios, matching morphological responses to physical and chemical parameters, measured at different partitions within the estuary. Thus, L. racemosa can be confirmed as a reliable sentinel plant for biomonitoring of estuaries impacted by anthropic pollution. PMID:24445776

  14. Fine particle emissions in three different combustion conditions of a wood chip-fired appliance - Particulate physico-chemical properties and induced cell death

    NASA Astrophysics Data System (ADS)

    Leskinen, J.; Tissari, J.; Uski, O.; Virén, A.; Torvela, T.; Kaivosoja, T.; Lamberg, H.; Nuutinen, I.; Kettunen, T.; Joutsensaari, J.; Jalava, P. I.; Sippula, O.; Hirvonen, M.-R.; Jokiniemi, J.

    2014-04-01

    A biomass combustion reactor with a moving grate was utilised as a model system to produce three different combustion conditions corresponding to efficient, intermediate, and smouldering combustion. The efficient conditions (based on a CO level of approximately 7 mg MJ-1) corresponded to a modern pellet boiler. The intermediate conditions (CO level of approximately 300 mg MJ-1) corresponded to non-optimal settings in a continuously fired biomass combustion appliance. The smouldering conditions (CO level of approximately 2200 mg MJ-1) approached a batch combustion situation. The gaseous and particle emissions were characterised under each condition. Moreover, the ability of fine particles to cause cell death was determined using the particle emissions samples. The physico-chemical properties of the emitted particles and their toxicity were considerably different between the studied combustion conditions. In the efficient combustion, the emitted particles were small in size and large in number. The PM1 emission was low, and it was composed of ash species. In the intermediate and smouldering combustion, the PM1 emission was higher, and the particles were larger in size and smaller in number. In both of these conditions, there were high-emission peaks that produced a significant fraction of the emissions. The PAH emissions were the lowest in the efficient combustion. The smouldering combustion conditions produced the largest PAH emissions. In efficient combustion conditions, the emitted fine particles had the highest potential to cause cell death. This finding was most likely observed because these fine particles were mainly composed of inorganic ash species, and their relative contents of Zn were high. Thus, even the PM1 from optimal biomass combustion might cause health effects, but in these conditions, the particle emissions per energy unit produced were considerably lower.

  15. Chemical Reactions of Portland Cement with Aqueous CO2 and Their Impacts on Cement's Mechanical Properties under Geologic CO2 Sequestration Conditions.

    PubMed

    Li, Qingyun; Lim, Yun Mook; Flores, Katharine M; Kranjc, Kelly; Jun, Young-Shin

    2015-05-19

    To provide information on wellbore cement integrity in the application of geologic CO2 sequestration (GCS), chemical and mechanical alterations were analyzed for cement paste samples reacted for 10 days under GCS conditions. The reactions were at 95 °C and had 100 bar of either N2 (control condition) or CO2 contacting the reaction brine solution with an ionic strength of 0.5 M adjusted by NaCl. Chemical analyses showed that the 3.0 cm × 1.1 cm × 0.3 cm samples were significantly attacked by aqueous CO2 and developed layer structures with a total attacked depth of 1220 μm. Microscale mechanical property analyses showed that the hardness and indentation modulus of the carbonated layer were 2-3 times greater than for the intact cement, but those in the portlandite-dissolved region decreased by ∼50%. The strength and elastic modulus of the bulk cement samples were reduced by 93% and 84%, respectively. The properties of the microscale regions, layer structure, microcracks, and swelling of the outer layers combined to affect the overall mechanical properties. These findings improve understanding of wellbore integrity from both chemical and mechanical viewpoints and can be utilized to improve the safety and efficiency of CO2 storage. PMID:25893278

  16. Process Options Description for Steam Reforming Flowsheet Model of INEEL Tank Farm Waste

    SciTech Connect

    Taylor, D.D.; Barnes, C.M.; Nichols, T.T.

    2002-05-21

    Technical information is provided herein that is required for development of a steady-state process simulation of a baseline steam reforming treatment train for Tank Farm waste at the Idaho National Engineering and Environmental Laboratory (INEEL). This document supercedes INEEL/EXT-2001-173, produced in FY2001 to support simulation of the direct vitrification treatment train which was the previous process baseline. A process block flow diagram for steam reforming is provided, together with a list of unit operations which constitute the process. A detailed description of each unit operation is given which includes its purpose, principal phenomena present, expected pressure and temperature ranges, key chemical species in the inlet steam, and the proposed manner in which the unit operation is to be modeled in the steady state process simulation. Models for the unit operations may be mechanistic (based on first principles), empirical (based solely on pilot test data without extrapolation) , or by correlations (based on extrapolative or statistical schemes applied to pilot test data). Composition data for the expected process feed streams is provided.

  17. CHEMICAL AND PHYSICAL CONDITIONS IN MOLECULAR CLOUD CORE DC 000.4-19.5 (SL42) IN CORONA AUSTRALIS

    SciTech Connect

    Hardegree-Ullman, E.; Whittet, D. C. B.; Harju, J.; Juvela, M.; Sipilae, O.; Hotzel, S.

    2013-01-20

    Chemical reactions in starless molecular clouds are heavily dependent on interactions between gas phase material and solid phase dust and ices. We have observed the abundance and distribution of molecular gases in the cold, starless core DC 000.4-19.5 (SL42) in Corona Australis using data from the Swedish ESO Submillimeter Telescope. We present column density maps determined from measurements of C{sup 18}O (J = 2-1, 1-0) and N{sub 2}H{sup +} (J = 1-0) emission features. Herschel data of the same region allow a direct comparison to the dust component of the cloud core and provide evidence for gas phase depletion of CO at the highest extinctions. The dust color temperature in the core calculated from Herschel maps ranges from roughly 10.7 to 14.0 K. This range agrees with the previous determinations from Infrared Space Observatory and Planck observations. The column density profile of the core can be fitted with a Plummer-like density distribution approaching n(r) {approx} r {sup -2} at large distances. The core structure deviates clearly from a critical Bonnor-Ebert sphere. Instead, the core appears to be gravitationally bound and to lack thermal and turbulent support against the pressure of the surrounding low-density material: it may therefore be in the process of slow contraction. We test two chemical models and find that a steady-state depletion model agrees with the observed C{sup 18}O column density profile and the observed N(C{sup 18}O) versus A{sub V} relationship.

  18. Identification of improvised explosives residues using physical-chemical analytical methods under real conditions after an explosion

    NASA Astrophysics Data System (ADS)

    Kotrlý, Marek; Mareš, Bohumil; Turková, Ivana; Beroun, Ivo

    2016-05-01

    Within the analysis of cases relating to the use of explosives for crimes, we have experienced a shift from using industrial explosives towards substances made in amateur and illegal way. Availability of industrial explosives is increasingly limited to a narrow sphere of subjects with a relevant permission. Thus, on the part of perpetrators, terrorists, ever greater attention is paid to illegal production of explosives that are easily made from readily available raw materials. Another alarming fact is the availability of information found on the internet. Procedures of preparation are often very simple and do not require even a deeper professional knowledge. Explosive characteristics are not actually accessible for many of these substances (detonation velocity, sensitivity, working capacity, brisance, physical and chemical stability, etc.). Therefore, a project is being implemented, which on grounds of assessment of individual information available in literature and on the internet, aiming at choosing individual areas of potentially abusable substances (e.g. mixtures of nitric acid (98%) with organic substances, mixtures nitromethane and tetranitromethane with organic substances, mixtures of chlorates and perchlorates of alkali metals with organic substances, chemically individual compounds of organic base type of perchloric acid, azides, fulminates, acetylides, picrates, styphnates of heavy metals, etc.). It is directed towards preparation of these explosives also in non-stoichiometric mixtures, conducting test explosives, determination of explosive characteristics (if they are unknown) and analysis of both primary phases and post-blast residues through available analytical techniques, such as gas and liquid chromatography with mass detection, FTIR, micro-Raman spectrometry, electron microscopy with microanalysis and Raman microspectrometry directly in SEM chamber for analysis at the level of individual microparticles. The received characteristics will be used to

  19. Physico-chemical changes of ZnO nanoparticles with different size and surface chemistry under physiological pH conditions.

    PubMed

    Gwak, Gyeong-Hyeon; Lee, Won-Jae; Paek, Seung-Min; Oh, Jae-Min

    2015-03-01

    We studied the physico-chemical properties of ZnO nanoparticles under physiological pH conditions (gastric, intestinal and plasma) as functions of their size (20 and 70 nm) and surface chemistry (pristine, L-serine, or citrate coating). ZnO nanoparticles were dispersed in phosphate buffered saline under physiological pH conditions and aliquots were collected at specific time points (0.5, 1, 4, 10 and 24 h) for further characterization. The pH values of the aqueous ZnO colloids at each condition were in the neutral to slightly basic range and showed different patterns depending on the original size and surface chemistry of the ZnO nanoparticles. The gastric pH condition was found to significantly dissolve ZnO nanoparticles up to 18-30 wt%, while the intestinal or plasma pH conditions resulted in much lower dissolution amounts than expected. Based on the X-ray diffraction patterns and X-ray absorption spectra, we identified partial phase transition of the ZnO nanoparticles from wurtzite to Zn(OH)2 under the intestinal and plasma pH conditions. Using scanning electron microscopy, we verified that the overall particle size and morphology of all ZnO nanoparticles were maintained regardless of the pH. PMID:25668417

  20. Impact of Flight Enthalpy, Fuel Simulant, and Chemical Reactions on the Mixing Characteristics of Several Injectors at Hypervelocity Flow Conditions

    NASA Technical Reports Server (NTRS)

    Drozda, Tomasz G.; Baurle, Robert A.; Drummond, J. Philip

    2016-01-01

    The high total temperatures or total enthalpies required to duplicate the high-speed flight conditions in ground experiments often place stringent requirements on the material selection and cooling needs for the test articles and intrusive flow diagnostic equipment. Furthermore, for internal flows, these conditions often complicate the use of nonintrusive diagnostics that need optical access to the test section and interior portions of the flowpath. Because of the technical challenges and increased costs associated with experimentation at high values of total enthalpy, an attempt is often made to reduce it. This is the case for the Enhanced Injection and Mixing Project (EIMP) currently underway in the Arc-Heated Scramjet Test Facility at the NASA Langley Research Center. The EIMP aims to investigate supersonic combustion ramjet (scramjet) fuel injection and mixing physics, improve the understanding of underlying physical processes, and develop enhancement strategies and functional relationships between mixing performance and losses relevant to flight Mach numbers greater than 8. The experiments will consider a "direct-connect" approach and utilize a Mach 6 nozzle to simulate the combustor entrance flow of a scramjet engine. However, while the value of the Mach number is matched to that expected at the combustor entrance in flight, the maximum value of the total enthalpy for these experiments is limited by the thermal-structural limits of the uncooled experimental hardware. Furthermore, the fuel simulant is helium, not hydrogen. The use of "cold" flows and non-reacting mixtures of fuel simulants for mixing experiments is not new and has been extensively utilized as a screening technique for scramjet fuel injectors. In this study, Reynolds-averaged simulations are utilized (RAS) to systematically verify the implicit assumptions used by the EIMP. This is accomplished by first performing RAS of mixing for two injector configurations at planned nominal experimental

  1. Evaluation of regional climate - air quality simulations over Europe for the period 1996-2006 with emphasis on tropospheric ozone: The impact of chemical boundary conditions

    NASA Astrophysics Data System (ADS)

    Akritidis, D.; Zanis, P.; Katragkou, E.; Tegoulias, I.; Poupkou, A.; Markakis, K.; Karacostas, Th.; Pytharoulis, I.

    2012-04-01

    A modeling system based on the air quality model CAMx driven off-line by the regional climate model RegCM3 is used for assessing the impact of lateral boundary conditions on tropospheric ozone over Europe for the period 1996-2006. The RegCM3 and CAMx simulations were performed on a 50 km x 50 km grid over Europe with RegCM3 driven by NCEP reanalysis fields. Average monthly concentration values obtained from the global chemistry climate model ECHAM5-MOZ were used as chemical boundary conditions for the CAMx simulations. The present period (1996-2006) was simulated two times. The first run (clean) was forced from constant lateral chemical boundary conditions and constant emissions based on the EMEP emissions of the year 1996. The second simulation (run1) was based on ECHAM5-MOZ chemical boundary conditions and emissions fixed for the year 1996. In order to evaluate the ability of the RegCM3/CAMx modeling system, simulated ozone concentrations are compared against near surface ozone measurements from the EMEP network. Since many of the stations of the EMEP network were not operating continuously during the time period of our study (1996-2006), we have used in the evaluation analysis only those stations that fulfill the criteria of 75% data availability for near surface ozone, choosing 87 stations from 23 European countries. Various statistical metrics are used for the model evaluation, including correlation coefficient (R), normalized standard deviation (NSD) and modified normalized mean bias (MNMB). The different lateral boundary conditions forcing resulted in changes of near surface ozone concentrations and variability. Using lateral boundary conditions obtained from the global chemistry climate model ECHAM5-MOZ (run1), the RegCM3/CAMx modeling system is capturing in a much better way the ozone monthly variability than using constant lateral boundary conditions (clean), especially for stations of northern and northwestern Europe. Concerning the correlation between

  2. Drying kinetics and physico-chemical characteristics of Osmo- dehydrated Mango, Guava and Aonla under different drying conditions.

    PubMed

    Kumar, P Suresh; Sagar, V R

    2014-08-01

    Mango (Mangiferra indica L), guava (Psiduim guajava L.) slices and aonla (Emblica officinalis L) segments were osmo-dried under four different dying conditions viz., cabinet drier (CD), vacuum oven drier (VOD), low temperature drier (LTD) and solar drier (SD) to evaluate the best drying condition for the fruits. It was found that vacuum oven drying was superior to other mode of drying as it holds maximum nutrients like acidity, ascorbic acid, sugar and water removal and moisture ratio of products. It was found through regression analysis that drying ratio and rehydration ratio was also superior in vacuum drying followed by cabinet drying. In addition, descriptive analysis on sensory score was also found best with vacuum drying while the Non-enzymatic browning (NEB), which is undesirable character on dried product, was more with solar drier. PMID:25114345

  3. Chemical Composition of the Fruit Oils of Five Fortunella Species Grown in the Same Pedoclimatic Conditions in Corsica (France).

    PubMed

    Sutour, Sylvain; Lurob, François; Bradesi, Pascale; Casanova, Joseph; Tomi, Félix

    2016-02-01

    Fruit oil from five species of kumquat (Fortunella japonica, F. margarita, F. crassifolia, F. obovata, and F. hindsii) grown in the same pedoclimatic conditions have been analyzed by a combination of chromatographic and spectroscopic techniques. The compositions of the five fruit oils were strongly dominated by limonene (84.2-96.3%). Other components present with appreciable contents were myrcene (1.3-12.9%) and germacrene D (0.3-2.4%). PMID:27032215

  4. Electrokinetic remediation of a Cu contaminated red soil by conditioning catholyte pH with different enhancing chemical reagents.

    PubMed

    Zhou, Dong-Mei; Deng, Chang-Fen; Cang, Long

    2004-07-01

    The effect of enhancement reagents on the efficiency of electrokinetic remediation of Cu contaminated red soil is evaluated. The enhancement agents were a mix of organic acids, including lactic acid+NaOH, HAc-NaAc and HAc-NaAc+EDTA. The soil was prepared to an initial Cu concentration of 438 mgkg(-1) by incubating the soil with CuSO4 solution in a flooded condition for 1 month. Sequential extraction showed that Cu was partitioned in the soil as follows: 195 mgkg(-1) as water soluble and exchangeable, 71 mgkg(-1) as carbonate bound and 105 mgkg(-1) as Fe and Mn oxides. The results indicate that neutralizing the catholyte pH maintains a lower soil pH compared to that without electrokinetic treatment. The electric currents varied depending upon the conditioning solutions and increased with an increasing applied voltage potential. The electroosmotic flow rate changed significantly when different conditioning enhancing reagents were used. It was observed that lactic acid+NaOH treatments resulted in higher soil electric conductivities than HAc-NaAc and HAc-NaAc+EDTA treatments. Ultimately, enhancement by lactic acid+NaOH resulted in highest removal efficiency (81% Cu removal) from the red soil. The presence of EDTA did not enhance Cu removal efficiencies from the red soil, because EDTA complexed with Cu to form negatively charge complexes, which slowly migrated toward the anode chamber retarding Cu2+ transport towards the cathode. PMID:15172599

  5. Assessment of groundwater chemical evolution for a spent nuclear fuel repository under prolonged temperate conditions: an application of efficient coupled groundwater flow and reactive transport simulation

    NASA Astrophysics Data System (ADS)

    Gylling, B.; Hartley, L. J.; Joyce, S. J.; Woollard, H.; Marsic, N.; Sidborn, M.; Puigdomenech, I.; Selroos, J. O.

    2014-12-01

    SKB has submitted a license application for a spent nuclear fuel repository at Forsmark sited in crystalline rocks of the Fennoscandian shield. In support of this application various quantitative assessments were made to demonstrate the long-term safety of the proposed repository. One such assessment involved simulation of groundwater chemical evolution to quantify impacts on safety functions for the disposal system related to the geochemical conditions, particularly salinity, pH and redox conditions. In the reference case the current temperate period lasts until 12,000 AD. A case of prolonged meteoric infiltration to 60,000 AD is also considered resulting from e.g. global warming. This is to fulfil a regulatory request to assess whether extended dilute water infiltration might lead to a rise in redox potential and also to an increase in erosion of the bentonite barrier due to formation of colloids. In order to perform long transient simulations of groundwater flow and solute transport with water-solute-rock interactions, new tools have been developed to closely couple geochemical, groundwater flow and transport calculations, and perform these efficiently using parallel computing techniques. In assessing this case, sensitivities are tested to the geochemical reaction schemes appropriate to the site. The results of this work predict that the chemical environment at repository depth stabilises at around 20,000 AD and shows little change beyond that. The salinity of the groundwater is governed by the low permeability (c. 10-19 m2) of the bedrock and by rock matrix diffusion, resulting in relatively shallow and slow circulation of groundwater. The chemical reactions influence concentrations of reactive species, the calculated pH and redox potential. In particular, the redox reactions thought to be relevant for the Forsmark site maintain reducing conditions at repository depth, even with infiltration at the ground surface of meteoric water with relatively high redox

  6. Testing phenotypic trade-offs in the chemical defence strategy of Scots pine under growth-limiting field conditions.

    PubMed

    Villari, Caterina; Faccoli, Massimo; Battisti, Andrea; Bonello, Pierluigi; Marini, Lorenzo

    2014-09-01

    Plants protect themselves from pathogens and herbivores through fine-tuned resource allocation, including trade-offs among resource investments to support constitutive and inducible defences. However, empirical research, especially concerning conifers growing under natural conditions, is still scarce. We investigated the complexity of constitutive and induced defences in a natural Scots pine (Pinus sylvestris L.) stand under growth-limiting conditions typical of alpine environments. Phenotypic trade-offs at three hierarchical levels were tested by investigating the behaviour of phenolic compounds and terpenoids of outer bark and phloem. We tested resource-derived phenotypic correlations between (i) constitutive and inducible defences vs tree ring growth, (ii) different constitutive defence metabolites and (iii) constitutive concentration and inducible variation of individual metabolites. Tree ring growth was positively correlated only with constitutive concentration of total terpenoids, and no overall phenotypic trade-offs between different constitutive defensive metabolites were found. At the lowest hierarchical level tested, i.e., at the level of relationship between constitutive and inducible variation of individual metabolites, we found that different compounds displayed different behaviours; we identified five different defensive metabolite response types, based on direction and strength of the response, regardless of tree age and growth rate. Therefore, under growth-limiting field conditions, Scots pine appears to utilize varied and complex outer bark and phloem defence chemistry, in which only part of the constitutive specialized metabolism is influenced by tree growth, and individual components do not appear to be expressed in a mutually exclusive manner in either constitutive or inducible metabolism. PMID:25194142

  7. Influence of variable chemical conditions on EDTA-enhanced transport of metal ions in mildly acidic groundwater

    USGS Publications Warehouse

    Kent, D.B.; Davis, J.A.; Joye, J.L.; Curtis, G.P.

    2008-01-01

    Adsorption of Ni and Pb on aquifer sediments from Cape Cod, Massachusetts, USA increased with increasing pH and metal-ion concentration. Adsorption could be described quantitatively using a semi-mechanistic surface complexation model (SCM), in which adsorption is described using chemical reactions between metal ions and adsorption sites. Equilibrium reactive transport simulations incorporating the SCMs, formation of metal-ion-EDTA complexes, and either Fe(III)-oxyhydroxide solubility or Zn desorption from sediments identified important factors responsible for trends observed during transport experiments conducted with EDTA complexes of Ni, Zn, and Pb in the Cape Cod aquifer. Dissociation of Pb-EDTA by Fe(III) is more favorable than Ni-EDTA because of differences in Ni- and Pb-adsorption to the sediments. Dissociation of Ni-EDTA becomes more favorable with decreasing Ni-EDTA concentration and decreasing pH. In contrast to Ni, Pb-EDTA can be dissociated by Zn desorbed from the aquifer sediments. Variability in adsorbed Zn concentrations has a large impact on Pb-EDTA dissociation.

  8. Laboratory Study of Chemical Speciation of Mercury in Lake Sediment and Water under Aerobic and Anaerobic Conditions

    PubMed Central

    Regnell, Olof; Tunlid, Anders

    1991-01-01

    Chemical speciation and partitioning of radiolabeled HgCl2 were studied in model aquatic systems consisting of undisturbed eutrophic lake sediment and water in plastic cylinders. The cylinders were either gradually made anaerobic by a gentle flow of N2-CO2 or kept aerobic by air flow. The proportion of methylated 203Hg was significantly higher, in both water and sediment, in the anaerobic systems than in the aerobic systems. The composition and total concentration of fatty acids originating from bacterial phospholipids, as well as the concentration of vitamin B12, including related cobalamins, were similar in sediments from the anaerobic and aerobic systems. Bacterial cell numbers were, on average, 3.6 times higher in the anaerobic water columns than in the aerobic ones. Volatilization of 203Hg occurred in all systems except in an autoclaved control and was of similar magnitudes in the anaerobic and aerobic systems. Incorporation of 203Hg into the sediment was significantly faster in the aerobic systems than in the anaerobic systems. These results suggest that episodes of anoxia in bottom waters and sediment cause an increase in net mercury methylation and, hence, an increase in bioavailable mercury. PMID:16348444

  9. Tribological efficacy and stability of phospholipid-based membrane lubricants in varying pH chemical conditions.

    PubMed

    Pawlak, Zenon; Urbaniak, Wieslaw; Afara, Isaac O; Yusuf, Kehinde Q; Banaszak-Piechowska, Agnieszka; Oloyede, Adekunle

    2016-03-01

    In this study, the authors examine the influence of joint chemical environment by measuring changes in the tribological properties (friction coefficient and charge density) of contacting surfaces of normal and degenerated cartilage samples in bath solutions of varying pH (2.0-9.0). Bovine articular cartilage samples (n = 54) were subjected to several surface measurements, including interfacial energy, contact angle, and friction coefficient, at varying pH. The samples were delipidized and then subjected to the same measurement protocols. Our results reveal that the interfacial energy and charge density, which have been shown to be related to friction coefficient, decrease with pH in the acidic range and approach constant values at physiological (or synovial fluid) pH of 7.4 and beyond it, i.e., toward basic pH domain. The authors conclude that this rather complex response explains the long-term efficacy with respect to ageing and associated pH changes, of the phospholipid layers that facilitate the almost frictionless, hydration-lubrication involving contact in the mammalian musculoskeletal system. PMID:26727914

  10. Tuning of crystal phase structure in hydrated WO3 nanoparticles under wet chemical conditions and studies on their photochromic properties

    NASA Astrophysics Data System (ADS)

    Songara, Sandhya; Gupta, Vatsana; Kumar Patra, Manoj; Singh, Jitendra; Saini, Lokesh; Siddaramana Gowd, Genekehal; Raj Vadera, Sampat; Kumar, Narendra

    2012-07-01

    Hydrated tungsten oxide nanoparticles have been synthesized using a simple wet chemical method while varying the concentration of HCl. XRD studies show that the variation in HCl concentration from 1 M to 6 M in the reaction results into gradual change in crystal structure of hydrated WO3 from hexagonal (WO3·0.33H2O) to pure orthorhombic (WO3·H2O), through a series of samples with mixed phase of the two indifferent ratios. The similar variations in the degree of hydration and phase variations have also been observed from Raman, FTIR and TGA studies. The average crystallite size of the hydrated WO3 particles was estimated to be ∼26 nm from XRD line broadening and AFM studies showed the formation of spherical shaped particles for all the samples. The photochromic studies were carried out on the composite films of these materials in the polymeric matrix of polyvinyl alcohol (PVA) while exposing to UV light. The composite films show interesting variations in the photochromic behavior depending on the crystal structure of hydrated WO3 filler. The photochromic behavior has been explained on the basis of EPR spectra of hydrated WO3.

  11. Effects of chlorine on freshwater fish under various time and chemical conditions: toxicity of chlorine to freshwater fish. Final report

    SciTech Connect

    Brooks, A.S.; Bartos, J.M.; Danos, P.T.

    1982-07-01

    Laboratory bioassays to determine the acute toxicity of monochloramine, dichloramine, hypochlorous acid, and hypochlorite ion to emerald shiners, channel catfish, and rainbow trout were conducted. Four exposure regimes typical of chlorination schedules at operating steam electric power plants were used. Fish were exposed to single 15-minute, 30-minute, 120-minute, and quadruple 30-minute periods. No mortality or LC50 values were determined for each species of fish and chemical species of chlorine. Hypochlorous acid was the most toxic form of chlorine studied, followed closely by dichloramine. Monochloramine and hypochlorite ion were three to four times less toxic than hypochlorous acid and dichloramine. On the average, emerald shiners were 1.8 times more sensitive to chlorine than channel catfish and 3.3 times more sensitive than rainbow trout to the four forms of chlorine. The fish were more tolerant of chlorine during short duration exposures and most sensitive during the continuous 120-minute exposures. The significant differences in toxicity noted among the various chlorine species suggest that careful attention should be paid not only to total residual chlorine but to both the chlorine and fish species present and the duration of exposure expected in establishing chlorination regimes.

  12. Effects of chemical composition and test conditions on the dynamic tensile response of Zr-based metallic glasses

    NASA Astrophysics Data System (ADS)

    Wang, F.; Laws, K. J.; Trujillo, C. P.; Brown, A. D.; Cerreta, E. K.; Hazell, P. J.; Quadir, M. Z.; Ferry, M.; Escobedo, J. P.

    2015-06-01

    The effects of impact velocity and temperature on the dynamic mechanical behavior of two bulk metallic glasses (BMG) with slightly different elemental compositions (Zr55Cu30Ni5Al30 and Zr46Cu38Ag8Al38) have been investigated. Bullet-shaped samples were accelerated by a gas gun to speeds in the 400 ~ 600m/s range and tested at room temperature and 250 °C. The specimens impacted a steel extrusion die which subjected them to high strains at high strain-rates. The extruded samples were subsequently soft recovered by using low density foams. The deformed specimens were examined by optical and electron microscopy, x-ray diffraction and hardness measurements. The characterization results aided to assess the effect of chemical composition on the microstructural evolution, i.e. phase changes or crystallization, which might influence the ductility on the nominally brittle amorphous BMGs. The most significant results from this study will be presented. School of Engineering and Information Technology, UNSW Canberra.

  13. Chemical composition and selected mechanical properties of Al-Zn alloy modified in plasma conditions by RF CVD

    NASA Astrophysics Data System (ADS)

    Kyzioł, Karol; Kluska, Stanisława; Januś, Marta; Środa, Marcin; Jastrzębski, Witold; Kaczmarek, Łukasz

    2014-08-01

    The paper reports results of the study of surface composition and selected functional properties of 7075 (Al-Zn) alloys modified in Ar, N2, SiH4 and CH4 atmosphere at reduced pressure. RF CVD (Radio Frequency Chemical Vapour Deposition) technique was used in the study. The type or weight percentage of carbon in each modification varied in the resultant SiN:H and SiCN:H coatings. Alloy samples were treated with Ar+ plasma etching and N+ ion implantation at reduced pressure. The tests proved the values of selected mechanical properties (hardness ca. 10.5 GPa, Young modulus ca. 95 GPa) and adhesion (delamination force ca. 11.5 mN) to be higher in the case of SiCN:H anti-wear coating (deposited in SiH4:CH4:N2 = 1:1:2 gas mixture) than the values of the respective parameters obtained in the remaining modifications. Further, carbon doped coatings (SiCN:H) exhibited significantly improved hardness (by about 50 to 70%) and nearly threefold increase in delamination force in comparison with SiCN:H coatings.

  14. Evaluation of Nursing Documentation Completion of Stroke Patients in the Emergency Department: A Pre-Post Analysis Using Flowsheet Templates and Clinical Decision Support.

    PubMed

    Richardson, Karen J; Sengstack, Patricia; Doucette, Jeffrey N; Hammond, William E; Schertz, Matthew; Thompson, Julie; Johnson, Constance

    2016-02-01

    The primary aim of this performance improvement project was to determine whether the electronic health record implementation of stroke-specific nursing documentation flowsheet templates and clinical decision support alerts improved the nursing documentation of eligible stroke patients in seven stroke-certified emergency departments. Two system enhancements were introduced into the electronic record in an effort to improve nursing documentation: disease-specific documentation flowsheets and clinical decision support alerts. Using a pre-post design, project measures included six stroke management goals as defined by the National Institute of Neurological Disorders and Stroke and three clinical decision support measures based on entry of orders used to trigger documentation reminders for nursing: (1) the National Institutes of Health's Stroke Scale, (2) neurological checks, and (3) dysphagia screening. Data were reviewed 6 months prior (n = 2293) and 6 months following the intervention (n = 2588). Fisher exact test was used for statistical analysis. Statistical significance was found for documentation of five of the six stroke management goals, although effect sizes were small. Customizing flowsheets to meet the needs of nursing workflow showed improvement in the completion of documentation. The effects of the decision support alerts on the completeness of nursing documentation were not statistically significant (likely due to lack of order entry). For example, an order for the National Institutes of Health Stroke Scale was entered only 10.7% of the time, which meant no alert would fire for nursing in the postintervention group. Future work should focus on decision support alerts that trigger reminders for clinicians to place relevant orders for this population. PMID:26679006

  15. MECHANICAL AND CHEMICAL PROPERTIES OF CEMENTITIOUS MATERIALS USING γ-2CaO.SiO2 UNDER THE SEVERAL CONDITIONS IN ACCELERATED CARBONATION CURING

    NASA Astrophysics Data System (ADS)

    Watanabe, Kenzo; Yokozeki, Kosuke; Torichigai, Takeshi; Sakai, Etsuo

    The experiments have been conducted in order to investigate the mechanical and chemical properties of mortar with three different binders under the several conditions in accelerated carbonation curing. As the results, the depth of carbonation varied among each mix proportion. It is proven that by increasing CO2 density in the mortar having γ-2CaO.SiO2, the CaCO3 production will increase, which leads to the increase of filling ability in the pore of mortar. Furthermore, as a result from the calculation of Tritium permeation, it shows that the permeation decreases with an increase of CO2 density.

  16. Process Options Description for Vitrification Flowsheet Model of INEEL Sodium Bearing Waste

    SciTech Connect

    Nichols, T.T.; Taylor, D.D.; Lauerhass, L.; Barnes, C.M.

    2002-02-21

    The technical information required for the development of a basic steady-state process simulation of the vitrification treatment train of sodium bearing waste (SBW) at Idaho National Engineering and Environmental Laboratory (INEEL) is presented. The objective of the modeling effort is to provide the predictive capability required to optimize an entire treatment train and assess system-wide impacts of local changes at individual unit operations, with the aim of reducing the schedule and cost of future process/facility design efforts. All the information required a priori for engineers to construct and link unit operation modules in a commercial software simulator to represent the alternative treatment trains is presented. The information is of a mid- to high-level nature and consists of the following: (1) a description of twenty-four specific unit operations--their operating conditions and constraints, primary species and key outputs, and the initial modeling approaches that will be used in the first year of the simulation's development; (2) three potential configurations of the unit operations (trains) and their interdependencies via stream connections; and (3) representative stream compositional makeups.

  17. Roller milling fractionation of green gram (Vigna radiata): optimization of milling conditions and chemical characterization of millstreams.

    PubMed

    Sakhare, Suresh D; Inamdar, Aashitosh A; Gaikwad, Shwetha B; D, Indrani; G, Vekateswara Rao

    2014-12-01

    In the view of recent growing interest in utilization of grain fractions as food ingredient, present investigation was carried out to evaluate the roller milling potential of green gram. The effect of conditioning moistures on green gram roller milling were studied. The results showed decrease in flour yield from 85.56 to 58.74 % with increase in conditioning moisture from 10 to 16 %. Higher yield of flour was observed from the first (C1), second (C2) and third (C3) reduction passages; whereas, the first (B1), second (B2) and third (B3) break passages produced less flour. The distribution of protein, dietary fiber, ash and fat in different flour streams and by-products from roller milled fractions of green gram showed wide variation. The protein content increased with increasing numbers of breaks and reductions in the flour streams. The highest protein content of 30.16 % was found in bran duster flour and lowest (11.32 %) in fine seed coat. The protein content of break streams was found lower than reduction streams. The dietary fiber content of coarse seed coat was highest (71.17 %) followed by the fine seed coat (57.22 %). The microstructure studies of milled fractions of green gram showed more deformed and damaged starch granules in reduction flour streams than break flour streams. PMID:25477653

  18. An Investigation on Soil Chemical Composition and Shallow Groundwater Condition in a Saline Area in Nakhon Panom Province, Thailand

    NASA Astrophysics Data System (ADS)

    Seeboonruang, U.

    2010-12-01

    The Mekong River Basin region is a potential salt-accumulated neighborhood. Several subbasin areas have been reported to have the saline soil problem and these include Lower Songkram River, Nam Oon Brook, Nam Thew Brook, and Namkam Brook. The study area is located on the lower of the Namkam River Basin mainly in 3 districts of the Nakhon Panom Province and these districts are Amphoe That Panom, Amphoe Nakae, and Amphoe Renu Nakhon. Soil salinity is found risen sparsely in some villages of these three districts. Generally, shallow groundwater is known to facilitate the distribution of dissolved salts away from the salinity sources and to pick up the salts to the top soils. Thus, groundwater plays a major role in salinity distribution everywhere. The objective of this research is to investigate the soil chemical composition and shallow groundwater evolution in the study area. Soil samples are analyzed using X-Ray Fluorescence Spectrometer (XRF). The depth to groundwater, groundwater pH, total dissolved solids (TDS), electrical resistivity (EC), and salinity are the parameters and the measurement takes place from October 2007 to present. There are 19 sampling locations distributed in the study area. The depth of the observation wells varies from 4 m to 40 m. Groundwater table is found to be up to 7 m below the groundwater surface and the depth is increasing from December to April. Groundwater pH is constantly less than 7 and greater than 4. Groundwater pH varies significantly between 10 mg/l to 45,000 mg/l and EC also differs between 10 µS/cm to 90,000 µS/cm. Most of groundwater sampled in the study area is slight blackish with salinity measured below 1.00 ppt and these are Ban Don Dang, Ban Wang Yang, Ban Na Khu, Ban Piman Ta, Pan Sala, and Ban Lao Tung. On the other hand, Ban Bo Dong Sorn and Ban Pra Song Noi have very saline shallow groundwater with salinity greater 1ppt. The results from the XRF show that SiO2 and Al2O3 are the main composition and the soil is

  19. Evaluation of chemical, biological, and physical conditions in the Winter Haven chain of lakes, Florida, March-June 1976

    USGS Publications Warehouse

    Reichenbaugh, R.C.; Hughes, G.H.

    1977-01-01

    Reconnaissance of water-quality conditions of 14 interconnected navigable lakes, in and around Winter Haven, Fla., revealed that in March and May, 1976 most were eutrophic, on the basis of high nutrient (nitrogen and phosphorus) concentrations. Lakes Lulu and Shipp were the most enriched as a result of surface runoff from residential, agricultural, and highly urbanized areas, and many years of municipal and industrial waste effluent input. Phytoplankton counts were greater than a million cells per milliliter in some lakes sampled; algal blooms have ocurred, and water clarity was low. The level of Lake Howard fell to the lowest stage recorded in 31 years during May 1976. The record low was likely due to rainfall deficiency. Leakage of water through the lake beds to the ground-water system is also possible, but determination of the escaping water volume would require additional study. (Woodard-USGS)

  20. Influence of recoil-implanted and thermally released iodine on I-SCC of Zircaloy-4 in PCI-conditions: chemical aspects

    NASA Astrophysics Data System (ADS)

    Fregonese, M.; Lefebvre, F.; Lemaignan, C.; Magnin, T.

    The pellet cladding interaction (PCI) phenomenon can lead to cladding failure by iodine induced stress corrosion cracking (I-SCC) during power transients. In these situations, the aggressive species is present as both, recoil implanted iodine in the cladding, and gaseous iodine thermally released in the gap. The aim of this work is to determine the respective roles of implanted and gaseous iodine in the SCC phenomenon. Two types of SCC tests have thus been performed. In the first one, zirconium and iodine recoil implanted tensile test specimens were used, with implantation profiles typical of those existing in a cladding under PCI conditions either on the dose or on the induced damage standpoint. These tests have shown that recoil implanted iodine has no chemical effect on the development of the SCC cracks. The second type of tests was performed on reference tensile test specimens at 350°C with iodine released either, in oxygen containing atmospheres or, at increasing temperatures. The iodine efficiency for cracks initiation was found to be stronger when no oxygen is available for repassivation and when iodine is released at higher temperature. These two conditions being fulfilled during PCI loading, since no gaseous oxygen is available in the fuel-to-clad gap, and since iodine is released through the pellet radical cracks at high temperature, thermally released iodine can be considered as the chemical active species responsible for SCC.

  1. Monolayer culturing and cloning of human pluripotent stem cells on laminin-521-based matrices under xeno-free and chemically defined conditions.

    PubMed

    Rodin, Sergey; Antonsson, Liselotte; Hovatta, Outi; Tryggvason, Karl

    2014-10-01

    A robust method for culturing human pluripotent stem (hPS) cells under chemically defined and xeno-free conditions is an important tool for stem cell research and for the development of regenerative medicine. Here, we describe a protocol for monolayer culturing of Oct-4-positive hPS cells on a specific laminin-521 (LN-521) isoform, under xeno-free and chemically defined conditions. The cells are dispersed into single-cell suspension and then plated on LN-521 isoform at densities higher than 5,000 cells per cm², where they attach, migrate and survive by forming small monolayer cell groups. The cells avidly divide and expand horizontally until the entire dish is covered by a confluent monolayer. LN-521, in combination with E-cadherin, allows cloning of individual hPS cells in separate wells of 96-well plates without the presence of rho-associated protein kinase (ROCK) inhibitors or any other inhibitors of anoikis. Characterization of cells maintained for several months in culture reveals pluripotency with a minimal degree of genetic abnormalities. PMID:25211513

  2. Experimental device for chemical osmosis measurement on natural clay-rock samples maintained at in situ conditions: implications for formation pressure interpretations.

    PubMed

    Rousseau-Gueutin, Pauline; de Greef, Vincent; Gonçalvès, Julio; Violette, Sophie; Chanchole, Serge

    2009-09-01

    In order to characterize the so-called coupled processes occurring in compacted clay rocks, the coupling coefficients must be identified. For this purpose, an original device which allows such measurement for undisturbed (natural) samples in their in situ conditions was developed. The present experimental device minimizes the fluid leaks improving the accuracy of the coupling parameter determination. Three chemical osmotic tests were performed on a cylindrical sample of Callovo-Oxfordian argilite. Room temperature variations during the chemical osmosis experiments required the implementation of temperature effects in the numerical model used for the interpretations. These variations offered the opportunity of an alternative method to estimate the compressibility of the fluid in the circuit connected to a measurement chamber located in the center of the sample. An osmotic efficiency of almost 0.2 for a concentration of 0.094 mol L(-1) is obtained for the Callovo-Oxfordian argilite. This value would explain only some part (approximately 0.10-0.15 MPa) of the overpressures (0.5-0.6 MPa) relative to the surrounding reservoirs measured in this formation. Others processes, such as thermo-osmosis, hydrodynamic boundary condition changes due to climate variations or creep behavior of the shale, could explain the remainder of the overpressures. PMID:19527907

  3. Method of conditional moments (MCM) for the Chemical Master Equation: a unified framework for the method of moments and hybrid stochastic-deterministic models.

    PubMed

    Hasenauer, J; Wolf, V; Kazeroonian, A; Theis, F J

    2014-09-01

    The time-evolution of continuous-time discrete-state biochemical processes is governed by the Chemical Master Equation (CME), which describes the probability of the molecular counts of each chemical species. As the corresponding number of discrete states is, for most processes, large, a direct numerical simulation of the CME is in general infeasible. In this paper we introduce the method of conditional moments (MCM), a novel approximation method for the solution of the CME. The MCM employs a discrete stochastic description for low-copy number species and a moment-based description for medium/high-copy number species. The moments of the medium/high-copy number species are conditioned on the state of the low abundance species, which allows us to capture complex correlation structures arising, e.g., for multi-attractor and oscillatory systems. We prove that the MCM provides a generalization of previous approximations of the CME based on hybrid modeling and moment-based methods. Furthermore, it improves upon these existing methods, as we illustrate using a model for the dynamics of stochastic single-gene expression. This application example shows that due to the more general structure, the MCM allows for the approximation of multi-modal distributions. PMID:23918091

  4. Ion mobility spectrometry versus classical physico-chemical analysis for assessing the shelf life of extra virgin olive oil according to container type and storage conditions.

    PubMed

    Garrido-Delgado, Rocío; Dobao-Prieto, M Mar; Arce, Lourdes; Aguilar, Joaquín; Cumplido, José L; Valcárcel, Miguel

    2015-03-01

    An experimental study was conducted to assess the stability of a single-variety (Arbequina) extra virgin olive oil (EVOO) as a function of container type and storage conditions over a period of 11 months. EVOO quality was assessed by using ion mobility spectrometry (IMS), which provides increased simplicity, expeditiousness, and relative economy. The results were compared with the ones obtained by using the official method based on classical physico-chemical analysis. Bag-in-box, metal, dark glass, clear glass, and polyethylene terephthalate containers holding EVOO were opened on a periodic basis for sampling to simulate domestic use; in parallel, other containers were kept closed until analysis to simulate the storage conditions on market shelves. The results of the physico-chemical and instrumental analyses led to similar conclusions. Thus, samples packaged in bag-in-box containers preserved oil quality for 11 months, better than other container types. The HS-GC-IMS results confirm that 2-heptenal and 1-penten-3-one are two accurate markers of EVOO quality. PMID:25645180

  5. Dynamics-based selective 2D {sup 1}H/{sup 1}H chemical shift correlation spectroscopy under ultrafast MAS conditions

    SciTech Connect

    Zhang, Rongchun; Ramamoorthy, Ayyalusamy

    2015-05-28

    Dynamics plays important roles in determining the physical, chemical, and functional properties of a variety of chemical and biological materials. However, a material (such as a polymer) generally has mobile and rigid regions in order to have high strength and toughness at the same time. Therefore, it is difficult to measure the role of mobile phase without being affected by the rigid components. Herein, we propose a highly sensitive solid-state NMR approach that utilizes a dipolar-coupling based filter (composed of 12 equally spaced 90° RF pulses) to selectively measure the correlation of {sup 1}H chemical shifts from the mobile regions of a material. It is interesting to find that the rotor-synchronized dipolar filter strength decreases with increasing inter-pulse delay between the 90° pulses, whereas the dipolar filter strength increases with increasing inter-pulse delay under static conditions. In this study, we also demonstrate the unique advantages of proton-detection under ultrafast magic-angle-spinning conditions to enhance the spectral resolution and sensitivity for studies on small molecules as well as multi-phase polymers. Our results further demonstrate the use of finite-pulse radio-frequency driven recoupling pulse sequence to efficiently recouple weak proton-proton dipolar couplings in the dynamic regions of a molecule and to facilitate the fast acquisition of {sup 1}H/{sup 1}H correlation spectrum compared to the traditional 2D NOESY (Nuclear Overhauser effect spectroscopy) experiment. We believe that the proposed approach is beneficial to study mobile components in multi-phase systems, such as block copolymers, polymer blends, nanocomposites, heterogeneous amyloid mixture of oligomers and fibers, and other materials.

  6. An effective freezing/thawing method for human pluripotent stem cells cultured in chemically-defined and feeder-free conditions

    PubMed Central

    Nishishita, Naoki; Muramatsu, Marie; Kawamata, Shin

    2015-01-01

    Culturing human Pluripotent Stem Cells (hPSC)s in chemically defined medium and feeder-free condition can facilitate metabolome and proteome analysis of culturing cells and medium, and reduce regulatory concerns for clinical application of cells. And in addition, if hPSC are passaged and cryopreserved in single cells it also facilitates quality control of cells at single cell level. Here we report a robust single cell freezing and thawing method of hPSCs cultured in chemically-defined medium TeSRTM-E8TM and on cost-effective recombinant human Vitronectin-N (rhVTN-N)-coated dish. Cells are dissociated into single cells with recombinant TrypLETM Select and 0.5 mM EDTA/PBS (3:1 solution) in the presence of Rock inhibitor and cryopreserved with chemically defined CryoStemTM. Approximately 60% of cells were viable after dissociation. AggrewellTM 400 was used to form cell clumps of 500 cells after thaw in the presence of Rock inhibitor and cells were cultured for two days with TeSR-E8. Cells clumps were then seeded on rhVTN-N-coated dish and cultured with TeSR-E8 for two days prior to the first passage after thawing. Number of viable cells at the first passage increased around 10 times of that just before freezing. This robust single cell freezing method for hPSCs cultured in chemically defined medium will facilitate quality control of cultured cells at single cell level before cryopreservation and consequently assure the quality of cells in frozen vials for further manipulation after thawing. PMID:25973330

  7. An effective freezing/thawing method for human pluripotent stem cells cultured in chemically-defined and feeder-free conditions.

    PubMed

    Nishishita, Naoki; Muramatsu, Marie; Kawamata, Shin

    2015-01-01

    Culturing human Pluripotent Stem Cells (hPSC)s in chemically defined medium and feeder-free condition can facilitate metabolome and proteome analysis of culturing cells and medium, and reduce regulatory concerns for clinical application of cells. And in addition, if hPSC are passaged and cryopreserved in single cells it also facilitates quality control of cells at single cell level. Here we report a robust single cell freezing and thawing method of hPSCs cultured in chemically-defined medium TeSR(TM)-E8(TM) and on cost-effective recombinant human Vitronectin-N (rhVTN-N)-coated dish. Cells are dissociated into single cells with recombinant TrypLE(TM) Select and 0.5 mM EDTA/PBS (3:1 solution) in the presence of Rock inhibitor and cryopreserved with chemically defined CryoStem(TM). Approximately 60% of cells were viable after dissociation. Aggrewell(TM) 400 was used to form cell clumps of 500 cells after thaw in the presence of Rock inhibitor and cells were cultured for two days with TeSR-E8. Cells clumps were then seeded on rhVTN-N-coated dish and cultured with TeSR-E8 for two days prior to the first passage after thawing. Number of viable cells at the first passage increased around 10 times of that just before freezing. This robust single cell freezing method for hPSCs cultured in chemically defined medium will facilitate quality control of cultured cells at single cell level before cryopreservation and consequently assure the quality of cells in frozen vials for further manipulation after thawing. PMID:25973330

  8. Effect of nontronite smectite clay on the chemical evolution of several organic molecules under simulated martian surface ultraviolet radiation conditions.

    PubMed

    Poch, Olivier; Jaber, Maguy; Stalport, Fabien; Nowak, Sophie; Georgelin, Thomas; Lambert, Jean-François; Szopa, Cyril; Coll, Patrice

    2015-03-01

    Most of the phyllosilicates detected at the surface of Mars today are probably remnants of ancient environments that sustained long-term bodies of liquid water at the surface or subsurface and were possibly favorable for the emergence of life. Consequently, phyllosilicates have become the main mineral target in the search for organics on Mars. But are phyllosilicates efficient at preserving organic molecules under current environmental conditions at the surface of Mars? We monitored the qualitative and quantitative evolutions of glycine, urea, and adenine in interaction with the Fe(3+)-smectite clay nontronite, one of the most abundant phyllosilicates present at the surface of Mars, under simulated martian surface ultraviolet light (190-400 nm), mean temperature (218 ± 2 K), and pressure (6 ± 1 mbar) in a laboratory simulation setup. We tested organic-rich samples that were representative of the evaporation of a small, warm pond of liquid water containing a high concentration of organics. For each molecule, we observed how the nontronite influences its quantum efficiency of photodecomposition and the nature of its solid evolution products. The results reveal a pronounced photoprotective effect of nontronite on the evolution of glycine and adenine; their efficiencies of photodecomposition were reduced by a factor of 5 when mixed at a concentration of 2.6 × 10(-2) mol of molecules per gram of nontronite. Moreover, when the amount of nontronite in the sample of glycine was increased by a factor of 2, the gain of photoprotection was multiplied by a factor of 5. This indicates that the photoprotection provided by the nontronite is not a purely mechanical shielding effect but is also due to stabilizing interactions. No new evolution product was firmly identified, but the results obtained with urea suggest a particular reactivity in the presence of nontronite, leading to an increase of its dissociation rate. PMID:25734356

  9. Chemical Constraints Governing the Origin of Metabolism: The Thermodynamic Landscape of Carbon Group Transformations under Mild Aqueous Conditions

    NASA Astrophysics Data System (ADS)

    Weber, Arthur L.

    2002-08-01

    The thermodynamics of organic chemistry under mild aqueous conditions was examined in order to begin to understand its influence on the structure and operation of metabolism and its antecedents. Free energies (ΔG) were estimated for four types of reactions of biochemical importance - carbon-carbon bond cleavage and synthesis, hydrogen transfer between carbon groups, dehydration of alcohol groups, and aldo-keto isomerization. The energies were calculated for mainly aliphatic groups composed of carbon, hydrogen, and oxygen. The energy values showed (1) that generally when carbon-carbon bond cleavage involves groups from different functional group classes (i.e., carboxylic acids, carbonyl groups, alcohols, and hydrocarbons), the transfer of the shared electron-pair to the more reduced carbon group is energetically favored over transfer to the more oxidized carbon group, and (2) that the energy of carbon-carbon bond transformation is primarily determined by the functional group class of the group that changes oxidation state in the reaction (i.e., the functional group class of the group that donates the shared electron-pair during cleavage, or that accepts the incipient shared electron-pair during synthesis). In contrast, the energy of hydrogen transfer between carbon groups is determined by the functional group class of both the hydrogen-donor group and the hydrogen-acceptor group. From these and other observations we concluded that the chemistry involved in the origin of metabolism (and to a lesser degree modern metabolism) was strongly constrained by (1) the limited redox-based transformation energy of organic substrates that is readily dissipated in a few energetically favorable irreversible reactions; (2) the energy dominance of a few transformation half-reactions that determines whether carbon-carbon bond transformation (cleavage or synthesis) is energetically favorable (ΔG < -3.5 kcal/mol), reversible (ΔG between +/-3.5 kcal/mol), or unfavorable (ΔG > +3

  10. Chemical constraints governing the origin of metabolism: the thermodynamic landscape of carbon group transformations under mild aqueous conditions

    NASA Technical Reports Server (NTRS)

    Weber, Arthur L.

    2002-01-01

    The thermodynamics of organic chemistry under mild aqueous conditions was examined in order to begin to understand its influence on the structure and operation of metabolism and its antecedents. Free energies (deltaG) were estimated for four types of reactions of biochemical importance carbon-carbon bond cleavage and synthesis, hydrogen transfer between carbon groups, dehydration of alcohol groups, and aldo-keto isomerization. The energies were calculated for mainly aliphatic groups composed of carbon, hydrogen, and oxygen. The energy values showed (1) that generally when carbon-carbon bond cleavage involves groups from different functional group classes (i.e., carboxylic acids, carbonyl groups, alcohols, and hydrocarbons), the transfer of the shared electron-pair to the more reduced carbon group is energetically favored over transfer to the more oxidized carbon group, and (2) that the energy of carbon-carbon bond transformation is primarily determined by the functional group class of the group that changes oxidation state in the reaction (i.e., the functional group class of the group that donates the shared electron-pair during cleavage, or that accepts the incipient shared electron-pair during synthesis). In contrast, the energy of hydrogen transfer between carbon groups is determined by the functional group class of both the hydrogen-donor group and the hydrogen-acceptor group. From these and other observations we concluded that the chemistry involved in the origin of metabolism (and to a lesser degree modern metabolism) was strongly constrained by (1) the limited redox-based transformation energy of organic substrates that is readily dissipated in a few energetically favorable irreversible reactions; (2) the energy dominance of a few transformation half-reactions that determines whether carbon-carbon bond transformation (cleavage or synthesis) is energetically favorable (deltaG < -3.5 kcal/mol), reversible (deltaG between +/-3.5 kcal/mol), or unfavorable (delta

  11. EVOLUTION OF CHEMICAL CONDITIONS AND ESTIMATED SOLUBILITY CONTROLS ON RADIONUCLIDES IN THE RESIDUAL WASTE LAYER DURING POST-CLOSURE AGING OF HIGH-LEVEL WASTE TANKS

    SciTech Connect

    Denham, M.; Millings, M.

    2012-08-28

    This document provides information specific to H-Area waste tanks that enables a flow and transport model with limited chemical capabilities to account for varying waste release from the tanks through time. The basis for varying waste release is solubilities of radionuclides that change as pore fluids passing through the waste change in composition. Pore fluid compositions in various stages were generated by simulations of tank grout degradation. The first part of the document describes simulations of the degradation of the reducing grout in post-closure tanks. These simulations assume flow is predominantly through a water saturated porous medium. The infiltrating fluid that reacts with the grout is assumed to be fluid that has passed through the closure cap and into the tank. The results are three stages of degradation referred to as Reduced Region II, Oxidized Region II, and Oxidized Region III. A reaction path model was used so that the transitions between each stage are noted by numbers of pore volumes of infiltrating fluid reacted. The number of pore volumes to each transition can then be converted to time within a flow and transport model. The bottoms of some tanks in H-Area are below the water table requiring a different conceptual model for grout degradation. For these simulations the reacting fluid was assumed to be 10% infiltrate through the closure cap and 90% groundwater. These simulations produce an additional four pore fluid compositions referred to as Conditions A through D and were intended to simulate varying degrees of groundwater influence. The most probable degradation path for the submerged tanks is Condition C to Condition D to Oxidized Region III and eventually to Condition A. Solubilities for Condition A are estimated in the text for use in sensitivity analyses if needed. However, the grout degradation simulations did not include sufficient pore volumes of infiltrating fluid for the grout to evolve to Condition A. Solubility controls for use

  12. Analysis of chemical abundances in planetary nebulae with [WC] central stars. I. Line intensities and physical conditions

    NASA Astrophysics Data System (ADS)

    García-Rojas, J.; Peña, M.; Morisset, C.; Mesa-Delgado, A.; Ruiz, M. T.

    2012-02-01

    Context. Planetary nebulae (PNe) around Wolf-Rayet [WR] central stars ([WR]PNe) constitute a particular photoionized nebula class that represents about 10% of the PNe with classified central stars. Aims: We analyse deep high-resolution spectrophotometric data of 12 [WR] PNe. This sample of [WR]PNe represents the most extensive analysed so far, at such high spectral resolution. We aim to select the optimal physical conditions in the nebulae to be used in ionic abundance calculations that will be presented in a forthcoming paper. Methods: We acquired spectra at Las Campanas Observatory with the 6.5-m telescope and the Magellan Inamori Kyocera (MIKE) spectrograph, covering a wavelength range from 3350 Å to 9400 Å. The spectra were exposed deep enough to detect, with signal-to-noise ratio higher than three, the weak optical recombination lines (ORLs) of O ii, C ii, and other species. We detect and identify about 2980 emission lines, which, to date, is the most complete set of spectrophotometric data published for this type of objects. From our deep data, numerous diagnostic line ratios for Te and ne are determined from collisionally excited lines (CELs), ORLs, and continuum measurements (H i Paschen continuum in particular). Results: Densities are closely described by the average of all determined values for objects with ne < 104 cm-3, and by ne([Cl iii]) for the densest objects. For some objects, ne([Ar iv]) is adopted as the characteristic density of the high ionization zone. For Te, we adopt a three-zone ionization scheme, where the low ionization zone is characterised by Te([N ii]), the medium ionization zone by Te([O iii]), and the highest ionization one by Te([Ar iv]) when available. We compute Te from the H i Paschen discontinuity and from He i lines. For each object, Te(H i) is, in general, consistent with Te derived from CELs, although it has a very large error. Values of Te(He i) are systematically lower than the Te derived from CELs. When comparing Te(H i

  13. Characterization of the pivotal carbon metabolism of Streptococcus suis serotype 2 under ex vivo and chemically defined in vitro conditions by isotopologue profiling.

    PubMed

    Willenborg, Jörg; Huber, Claudia; Koczula, Anna; Lange, Birgit; Eisenreich, Wolfgang; Valentin-Weigand, Peter; Goethe, Ralph

    2015-02-27

    Streptococcus suis is a neglected zoonotic pathogen that has to adapt to the nutritional requirements in the different host niches encountered during infection and establishment of invasive diseases. To dissect the central metabolic activity of S. suis under different conditions of nutrient availability, we performed labeling experiments starting from [(13)C]glucose specimens and analyzed the resulting isotopologue patterns in amino acids of S. suis grown under in vitro and ex vivo conditions. In combination with classical growth experiments, we found that S. suis is auxotrophic for Arg, Gln/Glu, His, Leu, and Trp in chemically defined medium. De novo biosynthesis was shown for Ala, Asp, Ser, and Thr at high rates and for Gly, Lys, Phe, Tyr, and Val at moderate or low rates, respectively. Glucose degradation occurred mainly by glycolysis and to a minor extent by the pentose phosphate pathway. Furthermore, the exclusive formation of oxaloacetate by phosphoenolpyruvate (PEP) carboxylation became evident from the patterns in de novo synthesized amino acids. Labeling experiments with S. suis grown ex vivo in blood or cerebrospinal fluid reflected the metabolic adaptation to these host niches with different nutrient availability; however, similar key metabolic activities were identified under these conditions. This points at the robustness of the core metabolic pathways in S. suis during the infection process. The crucial role of PEP carboxylation for growth of S. suis in the host was supported by experiments with a PEP carboxylase-deficient mutant strain in blood and cerebrospinal fluid. PMID:25575595

  14. Characterization of the Pivotal Carbon Metabolism of Streptococcus suis Serotype 2 under ex Vivo and Chemically Defined in Vitro Conditions by Isotopologue Profiling*

    PubMed Central

    Willenborg, Jörg; Huber, Claudia; Koczula, Anna; Lange, Birgit; Eisenreich, Wolfgang; Valentin-Weigand, Peter; Goethe, Ralph

    2015-01-01

    Streptococcus suis is a neglected zoonotic pathogen that has to adapt to the nutritional requirements in the different host niches encountered during infection and establishment of invasive diseases. To dissect the central metabolic activity of S. suis under different conditions of nutrient availability, we performed labeling experiments starting from [13C]glucose specimens and analyzed the resulting isotopologue patterns in amino acids of S. suis grown under in vitro and ex vivo conditions. In combination with classical growth experiments, we found that S. suis is auxotrophic for Arg, Gln/Glu, His, Leu, and Trp in chemically defined medium. De novo biosynthesis was shown for Ala, Asp, Ser, and Thr at high rates and for Gly, Lys, Phe, Tyr, and Val at moderate or low rates, respectively. Glucose degradation occurred mainly by glycolysis and to a minor extent by the pentose phosphate pathway. Furthermore, the exclusive formation of oxaloacetate by phosphoenolpyruvate (PEP) carboxylation became evident from the patterns in de novo synthesized amino acids. Labeling experiments with S. suis grown ex vivo in blood or cerebrospinal fluid reflected the metabolic adaptation to these host niches with different nutrient availability; however, similar key metabolic activities were identified under these conditions. This points at the robustness of the core metabolic pathways in S. suis during the infection process. The crucial role of PEP carboxylation for growth of S. suis in the host was supported by experiments with a PEP carboxylase-deficient mutant strain in blood and cerebrospinal fluid. PMID:25575595

  15. Optimization of chemical induction conditions for human herpesvirus 8 (HHV-8) reactivation with 12-O-tetradecanoyl-phorbol-13-acetate (TPA) from latently-infected BC-3 cells.

    PubMed

    Ma, Wenbin; Galvin, Teresa A; Ma, Hailun; Ma, Yunkun; Muller, Jacqueline; Khan, Arifa S

    2011-05-01

    Human herpesvirus 8 (HHV-8) persists as episomal DNA in latently-infected cells and can establish two alternative life cycles, latent or lytic. 12-O-tetradecanoyl-phorbol-13-acetate (TPA) is a known inducer of HHV-8 in several human primary effusion lymphoma cell lines and has been widely used for HHV-8 reactivation; however, induction conditions have differed, resulting in varying levels of virus expression. We have used HHV-8 latently-infected BC-3 cells as a model to determine critical parameters for optimizing virus reactivation by TPA. We found that cell growth properties and drug treatment conditions were important for maximum reactivation of HHV-8. Addition of TPA to cells in the early log phase of a sigmoidal growth curve, which was tightly associated with high percentage of the cells in early S phase and with lower histone deacetylase activity in the cells, provided the optimum cell conditions for latent virus to switch to lytic replication. Furthermore, increasing TPA concentration (up to 320 ng per ml) at 48 h exposure time resulted in increased virus production. The results demonstrate the use of a step-wise strategy with chemical induction that may facilitate broad detection of latent DNA viruses and novel virus discovery. PMID:21470875

  16. Estimating pesticide sampling rates by the polar organic chemical integrative sampler (POCIS) in the presence of natural organic matter and varying hydrodynamic conditions

    USGS Publications Warehouse

    Charlestra, Lucner; Amirbahman, Aria; Courtemanch, David L.; Alvarez, David A.; Patterson, Howard

    2012-01-01

    The polar organic chemical integrative sampler (POCIS) was calibrated to monitor pesticides in water under controlled laboratory conditions. The effect of natural organic matter (NOM) on the sampling rates (Rs) was evaluated in microcosms containing -1 of total organic carbon (TOC). The effect of hydrodynamics was studied by comparing Rs values measured in stirred (SBE) and quiescent (QBE) batch experiments and a flow-through system (FTS). The level of NOM in the water used in these experiments had no effect on the magnitude of the pesticide sampling rates (p > 0.05). However, flow velocity and turbulence significantly increased the sampling rates of the pesticides in the FTS and SBE compared to the QBE (p < 0.001). The calibration data generated can be used to derive pesticide concentrations in water from POCIS deployed in stagnant and turbulent environmental systems without correction for NOM.

  17. Role of hydraulic and chemical signals in leaves, stems and roots in the stomatal behaviour of olive trees under water stress and recovery conditions.

    PubMed

    Torres-Ruiz, Jose M; Diaz-Espejo, Antonio; Perez-Martin, Alfonso; Hernandez-Santana, Virginia

    2015-04-01

    The control of plant transpiration by stomata under water stress and recovery conditions is of paramount importance for plant performance and survival. Although both chemical and hydraulic signals emitted within a plant are considered to play a major role in controlling stomatal dynamics, they have rarely been assessed together. The aims of this study were to evaluate (i) the dynamics of chemical and hydraulic signals at leaf, stem and root level, and (ii) their effect on the regulation of stomatal conductance (gs) during water stress and recovery. Measurements of gs, water potential, abscisic acid (ABA) content and loss of hydraulic functioning at leaf, stem and root level were conducted during a water stress and recovery period imposed on 1-year-old olive plants (Olea europaea L.). Results showed a strong hydraulic segmentation in olive plants, with higher hydraulic functioning losses in roots and leaves than in stems. The dynamics of hydraulic conductance of roots and leaves observed as water stress developed could explain both a protection of the hydraulic functionality of larger organs of the plant (i.e., branches, etc.) and a role in the down-regulation of gs. On the other hand, ABA also increased, showing a similar pattern to gs dynamics, and thus its effect on gs in response to water stress cannot be ruled out. However, neither hydraulic nor non-hydraulic factors were able to explain the delay in the full recovery of gs after soil water availability was restored. PMID:25030936

  18. Effects of different crosslinking conditions on the chemical-physical properties of a novel bio-inspired composite scaffold stabilised with 1,4-butanediol diglycidyl ether (BDDGE).

    PubMed

    Nicoletti, A; Fiorini, M; Paolillo, J; Dolcini, L; Sandri, M; Pressato, D

    2013-01-01

    Serious cartilage lesions (Outerbridge III, IV) may be successfully treated with a three-layered gradient scaffold made by magnesium-doped hydroxyapatite and type I collagen, manufactured through a bio-inspired process and stabilised by a reactive bis-epoxy (1,4-butanediol diglycidyl ether, BDDGE). Each layer was analysed to elucidate the effects of crosslinking variables (concentration, temperature and pH). The chemical stabilisation led to an homogeneous and aligned collagenous matrix: the fibrous structures switched to a laminar foils-based arrangement and organic phases acquired an highly coordinated 3D-organization. These morphological features were strongly evident when crosslinking occurred in alkaline solution, with BDDGE concentration of at least 1 wt%. The optimised crosslinking conditions did not affect the apatite nano-crystals nucleated into self-assembling collagen fibres. The present work allowed to demonstrate that acting on BDDGE reaction parameters might be an useful tool to control the chemical-physical properties of bio-inspired scaffold suitable to heal wide osteochondral defects, even through arthroscopic procedure. PMID:23053811

  19. Chemical response of Picea glehnii seed-epiphytic Penicillium species to Pythium vexans under in vitro competitive conditions for mycelial growth.

    PubMed

    Yamaji, Keiko; Hashidoko, Yasuyuki; Fukushi, Yukiharu; Tahara, Satoshi

    2005-04-01

    The potential protection of Picea glehnii seedlings from damping-off by seed-epiphytic Penicillium species was investigated. We studied the chemical response of seed-epiphytic Penicillium species (Pen. cyaneum, Pen. damascenum, and Pen. implicatum) to Pythium vexans, a damping-off fungus, in vitro. Penicillium species were cultured singly or cocultured with Pyt. vexans for 14 or 18 d, and mycelial growth, pH of culture filtrate, antifungal activity of the culture filtrate against Pyt. vexans, and the amount of antifungal compound produced by each Penicillium species, were examined. The filtrate of both the single culture of Penicillium and the coculture of Penicillium and Pyt. vexans showed antifungal activity against Pyt. vexans. In a coculture with Pyt. vexans, Pen. cyaneum produced an antifungal compound (patulin) as in the single culture. Pen. damascenum cocultured with Pyt. vexans produced an antifungal compound (citrinin), as it did in the single culture and in larger amounts on day 10. Pen. implicatum produced two antifungal compounds, frequentin and palitantin, and the ratio of frequentin (with higher antifungal activity than palitantin) to palitantin was higher in the coculture with Pyt. vexans than in the single culture. Our results indicate that these Penicillium species have the ability to produce antifungal compounds and to keep anti-fungal activity under competitive condition with Pyt. vexans. The chemical response of these Penicillium species to Pyt. vexans may contribute to protect P. glehnii seedlings from damage by Pyt. vexans. PMID:16124252

  20. Non-integrating episomal plasmid-based reprogramming of human amniotic fluid stem cells into induced pluripotent stem cells in chemically defined conditions.

    PubMed

    Slamecka, Jaroslav; Salimova, Lilia; McClellan, Steven; van Kelle, Mathieu; Kehl, Debora; Laurini, Javier; Cinelli, Paolo; Owen, Laurie; Hoerstrup, Simon P; Weber, Benedikt

    2016-01-01

    Amniotic fluid stem cells (AFSC) represent an attractive potential cell source for fetal and pediatric cell-based therapies. However, upgrading them to pluripotency confers refractoriness toward senescence, higher proliferation rate and unlimited differentiation potential. AFSC were observed to rapidly and efficiently reacquire pluripotency which together with their easy recovery makes them an attractive cell source for reprogramming. The reprogramming process as well as the resulting iPSC epigenome could potentially benefit from the unspecialized nature of AFSC. iPSC derived from AFSC also have potential in disease modeling, such as Down syndrome or β-thalassemia. Previous experiments involving AFSC reprogramming have largely relied on integrative vector transgene delivery and undefined serum-containing, feeder-dependent culture. Here, we describe non-integrative oriP/EBNA-1 episomal plasmid-based reprogramming of AFSC into iPSC and culture in fully chemically defined xeno-free conditions represented by vitronectin coating and E8 medium, a system that we found uniquely suited for this purpose. The derived AF-iPSC lines uniformly expressed a set of pluripotency markers Oct3/4, Nanog, Sox2, SSEA-1, SSEA-4, TRA-1-60, TRA-1-81 in a pattern typical for human primed PSC. Additionally, the cells formed teratomas, and were deemed pluripotent by PluriTest, a global expression microarray-based in-silico pluripotency assay. However, we found that the PluriTest scores were borderline, indicating a unique pluripotent signature in the defined condition. In the light of potential future clinical translation of iPSC technology, non-integrating reprogramming and chemically defined culture are more acceptable. PMID:26654216

  1. Multispecies reactive tracer test in an aquifer with spatially variable chemical conditions, Cape Cod, Massachusetts: Dispersive transport of bromide and nickel

    USGS Publications Warehouse

    Hess, K.M.; Davis, J.A.; Kent, D.B.; Coston, J.A.

    2002-01-01

    Dispersive transport of groundwater solutes was investigated as part of a multispecies reactive tracer test conducted under spatially variable chemical conditions in an unconfined, sewage-contaminated sand and gravel aquifer on Cape Cod, Massachusetts. Transport of the nonreactive tracer bromide (Br) reflected physical and hydrologic processes. Transport of the reactive tracer nickel (Ni) complexed with an organic ligand (NiEDTA) varied in response to pH and other chemical conditions within the aquifer. A loss of about 14% of the Ni mass was calculated from the distribution of tracers through time. This loss is consistent with reversible adsorption of NiEDTA onto the iron and aluminum oxyhydroxide coatings on the aquifer sediments. The Ni consistently lagged behind Br with a calculated retardation coefficient of 1.2. Longitudinal dispersivities reached constant values of 2.2 and 1.1 m for Br and Ni, respectively, by at least 69 m of travel. The smaller dispersivity for Ni possibly was due to nonlinear or spatially variant adsorption of NiEDTA. In the upper, uncontaminated zone of the aquifer, longitudinal dispersion of Ni was greater than that of Br early in the test as a result of reversible adsorption of NiEDTA. In general, transverse dispersivities were much smaller (horizontal: 1.4-1.5 ?? 10-2 m; vertical: 0.5-3.8 ?? 10-3 m) than the longitudinal dispersivities. The Br results are similar to those from a test conducted eight years earlier, suggesting that transport parameters are spatially stationary within the aquifer at the scale of 300 m covered by the spatially overlapping tests. A significant difference between the two tests was the travel distance (69 and 26 m) needed to reach a constant longitudinal dispersivity.

  2. Effect of process conditions and chemical composition on the microstructure and properties of chemically vapor deposited SiC, Si, ZnSe, ZnS and ZnS(x)Se(1-x)

    NASA Technical Reports Server (NTRS)

    Pickering, Michael A.; Taylor, Raymond L.; Goela, Jitendra S.; Desai, Hemant D.

    1992-01-01

    Subatmospheric pressure CVD processes have been developed to produce theoretically dense, highly pure, void-free and large area bulk materials, SiC, Si, ZnSe, ZnS and ZnS(x)Se(1-x). These materials are used for optical elements, such as mirrors, lenses and windows, over a wide spectral range from the VUV to the IR. We discuss the effect of CVD process conditions on the microstructure and properties of these materials, with emphasis on optical performance. In addition, we discuss the effect of chemical composition on the properties of the composite material ZnS(x)Se(1-x). We first present a general overview of the bulk CVD process and the relationship between process conditions, such as temperature, pressure, reactant gas concentration and growth rate, and the microstructure, morphology and properties of CVD-grown materials. Then we discuss specific results for CVD-grown SiC, Si, ZnSe, ZnS and ZnS(x)Se(1-x).

  3. Physico-chemical Stability of MabThera Drug-product Solution for Subcutaneous Injection under in-use Conditions with Different Administration Materials.

    PubMed

    Mueller, Claudia; Dietel, Elke; Heynen, Severin R; Nalenz, Heiko; Goldbach, Pierre; Mahler, Hanns-Christian; Schmidt, Johannes; Grauschopf, Ulla; Schoenhamnmer, Karin

    2015-01-01

    MabThera is an essential component of the standard-of-care regimens in the treatment of non-Hodgkin lymphoma and Chronic Lymphatic Leukemia. MabThera for subcutaneous injection is a novel line extension that has been approved by the European Medicines Agency for the treatment of patients with follicular lymphoma and diffuse large B-cell lymphoma. This study aimed to evaluate in-use stability data of MabThera subcutaneous drug-product solution in single-use syringes for subcutaneous administration according to the European Medicines Agency guideline. The drug-product solution was exposed to material contact surfaces of five different administration setups commonly used in subcutaneous drug delivery. MabThera subcutaneous was transferred under aseptic conditions into polypropylene and polycarbonate syringes and stored for 1, 2, and 4 weeks at 2°C to 8°C followed by 24 hours at 30°C. After storage, subcutaneous administration was simulated and MabThera subcutaneous drug-product solution quality attributes were evaluated by using compendial physico-chemical tests, as well as suitable and validated molecule- and formulation-specific analytical methods. MabThera subcutaneous vials were treated and analyzed in parallel. The physico-chemical results of MabThera subcutaneous in the different setups were comparable to the control for all timepoints. No change in drug-product quality after storage and simulated administration was found compared to the control. However, since single-dose products do not contain preservatives, microbial contamination and growth needs to be avoided and product sterility needs to be ensured. The results showed that MabThera subcutaneous remains compatible and stable, from a physico-chemical perspective, for up to 4 weeks at 2°C to 8°C followed by 24 hours at 30°C with the contact materials tested in this study. In order to avoid and minimize microbial growth, MabThera subcutaneous should be used immediately after removal from the original

  4. Chemical behaviour of seven aromatic diisocyanates (toluenediisocyanates and diphenylmethanediisocyanates) under in vitro conditions in relationship to their results in the Salmonella/microsome test.

    PubMed

    Seel, K; Walber, U; Herbold, B; Kopp, R

    1999-01-13

    mixed with water. The biological test ingredients accelerated the reduction of the MDI content. Within 45 s, more than two thirds of the MDI disappeared. Evidently, the chemical reactions continue during incubation. It is assumed that the contrasting results of TDI and MDI in the Salmonella/microsome test are due to the different reaction patterns-and reaction products-of the predissolved diisocyanates created under the specific conditions of the test. These findings indicate that the chemical interactions between reactive test compounds and solvents or test media need to be considered in the interpretation of the relevance of test results. PMID:10036332

  5. The research of Iodine pool pressure of chemical oxygen-iodine laser in non-equilibrium condition and its automatic control system design

    NASA Astrophysics Data System (ADS)

    Zhou, Songqing; Qu, Pubo; Ren, Weiyan

    2013-05-01

    In the working process of chemical oxy-iodigenne laser(COIL), the change of iodine pool pressure is complicated. As a result, it causes some mis-judgements, such as the damage of heater and the leakage of iodine steam. Further more, when the heater electric circuit is in a single working status, and after the heater switch is on or off, there exists a buffer time for the stabilization of iodine pool pressure, which is a relatively long time, and the minimum buffer pressure exceeds to 19 torr . Of course, it increases the preparing time for steady operation of laser, and reduces the quality of laser beam. In this paper, we study the iodine pool pressure of COIL in non-equilibrium condition, and analyze the mutation and the serious buffer phenomenon of iodine steam pressure. At the same time, we design an automatic control system for iodine pool pressure, which consists of five modules, such as data collection, automatic control, manual control, heater electric circuit, and the setting and display of pressure. This system uses two kinds of heater electric circuits, in this way, the serious buffer phenomenon of iodine pool pressure is effectively avoided. As a result, the maximal buffer pressure reduces to 4 torr, this makes sure that the iodine steam pressure is suitable for the operation of COIL, which produces a good condition for the steady operation of laser system and an excellent laser output.

  6. Chemical Changes in Pore Water Composition due to CO2 Injection Under In-Situ P-T Condition of the Altmark Gas Reservoir, Germany

    NASA Astrophysics Data System (ADS)

    Huq, F.; Nowak, M.; Haderlein, S.; Grathwohl, P.

    2012-12-01

    CO2 storage in depleted gas reservoir combined with enhanced gas recovery may be an economically feasible option to mitigate global warming. The Altmark gas field, located in the western part of the Northeast German Basin, is being considered as a potential candidate for this purpose. Under reservoir conditions (50 bars and 125°C), the CO2 saturated water causes dissolution and subsequent precipitation of minerals of the surrounding rock matrix. Therefore, the main objective of the current study was to investigate the chemical changes in fluid composition due to dissolution/precipitation of minerals under controlled laboratory conditions. A dry sandstone plug from the Altmark reservoir was mounted in a newly designed autoclave system and flushed by a pre-equilibrated mixture of water saturated with CO2 at a constant flow rate of 0.25 cm/h for 12 days at reservoir conditions. Fluid samples were taken at regular intervals for major and trace element analysis and pH was measured simultaneously in the partially de-gassed samples. Fluid analysis showed an increased concentration of Na, K and Cl ions at the beginning indicating early leaching of halite and sylvite which initially inhibited the dissolution of alkali feldspars. Feldspar dissolution occurred later and slower indicated by lower concentrations of Na and K reflecting the lower solubility and slow dissolution kinetics of feldspar. Dissolution of anhydrite was predominantly observed from the increased concentration of Ca and SO4 at earlier time periods. However, the Ca/SO4 molar ratio (>1) indicated the concurrent dissolution of both calcite and anhydrite. The presence of carbonates buffered the pH until day 6. Moreover, the mobilization of Mn, Mg, Ba and Fe might be derived from carbonate impurities. Thermodynamic calculations of mineral saturation indices enabled an evaluation of the CO2-water-rock interactions during the experiment and highlighted the dissolution of the Ca-bearing minerals in the studied

  7. The acute toxicity of chemically and physically dispersed crude oil to key arctic species under arctic conditions during the open water season

    PubMed Central

    Gardiner, William W; Word, Jack Q; Word, Jack D; Perkins, Robert A; McFarlin, Kelly M; Hester, Brian W; Word, Lucinda S; Ray, Collin M

    2013-01-01

    The acute toxicity of physically and chemically dispersed crude oil and the dispersant Corexit 9500 were evaluated for key Arctic species. The copepod Calanus glacialis, juvenile Arctic cod (Boreogadus saida), and larval sculpin (Myoxocephalus sp.) were tested under conditions representative of the Beaufort and Chukchi Seas during the ice-free season. The toxicity of 3 water-accommodated fractions (WAF) of Alaska North Slope crude oil was examined with spiked, declining exposures. A dispersant-only test was conducted with the copepod C. glacialis. Each preparation with oil (WAF, breaking wave WAF [BWWAF], and chemically enhanced WAF [CEWAF]) produced distinct suites of hydrocarbon constituents; the total concentrations of oil were lowest in WAF and highest in CEWAF preparations. The relative sensitivity for the different species and age classes was similar within each WAF type. Median lethal concentration values based on total petroleum hydrocarbons ranged from 1.6 mg/L to 4.0 mg/L for WAF and BWWAF treatments and from 22 mg/L to 62 mg/L for CEWAF. For Corexit 9500 exposures, median lethal concentration values ranged from 17 mg/L to 50 mg/L. The differences in the relative toxicity among the accommodated fractions indicated that the majority of petroleum hydrocarbons in the CEWAF are in less acutely toxic forms than the components that dominate the WAF or BWWAF. Further evaluation showed that the parent polycyclic aromatic hydrocarbon compounds, specifically naphthalene, were highly correlated to acute toxicity. Environ Toxicol Chem 2013;32:2284–2300. PMID:23765555

  8. The influence of reservoirs, climate, land use and hydrologic conditions on loads and chemical quality of dissolved organic carbon in the Colorado River

    NASA Astrophysics Data System (ADS)

    Miller, Matthew P.

    2012-09-01

    Longitudinal patterns in dissolved organic carbon (DOC) loads and chemical quality were identified in the Colorado River from the headwaters in the Rocky Mountains to the United States-Mexico border from 1994 to 2011. Watershed- and reach-scale climate, land use, river discharge and hydrologic modification conditions that contribute to patterns in DOC were also identified. Principal components analysis (PCA) identified site-specific precipitation and reach-scale discharge as being correlated with sites in the upper basin, where there were increases in DOC load from the upstream to downstream direction. In the lower basin, where DOC load decreased from upstream to downstream, sites were correlated with site-specific temperature and reach-scale population, urban land use and hydrologic modification. In the reaches containing Lakes Powell and Mead, the two largest reservoirs in the United States, DOC quantity decreased, terrestrially derived aromatic DOC was degraded and/or autochthonous less aromatic DOC was produced. Taken together, these results suggest that longitudinal patterns in the relatively unregulated upper basin are influenced by watershed inputs of water and DOC, whereas DOC patterns in the lower basin are reflective of a balance between watershed contribution of water and DOC to the river and loss of water and DOC due to hydrologic modification and/or biogeochemical processes. These findings suggest that alteration of constituent fluxes in rivers that are highly regulated may overshadow watershed processes that would control fluxes in comparable unregulated rivers. Further, these results provide a foundation for detailed assessments of factors controlling the transport and chemical quality of DOC in the Colorado River.

  9. Seasonal behavior and long-term trends of tropospheric ozone, its precursors and chemical conditions over Iran: A view from space

    NASA Astrophysics Data System (ADS)

    Choi, Yunsoo; Souri, Amir Hossein

    2015-04-01

    annual TCO (∼0.59 ± 0.56 DU yr-1) but decreases in minimum annual TCO (∼-0.42 ± 0.60 DU yr-1) caused by an increase in NO2 species and annual CO (∼-0.95 ± 0.41 × 1016 molec./cm2 yr-1) partly resulting from the transport of reduced CO. The time series of the HCHO/NO2 column ratio (a proxy for the chemical conditions) indicated that during the last decade, the cities of Tehran, Ahvaz, and Isfahan exhibited steady chemical conditions while Tabriz and Mashhad exhibited a change from NOx-saturated/mixed to more NOx-sensitive chemical conditions.

  10. Effects of lactic acid bacteria with bacteriocinogenic potential on the fermentation profile and chemical composition of alfalfa silage in tropical conditions.

    PubMed

    Silva, V P; Pereira, O G; Leandro, E S; Da Silva, T C; Ribeiro, K G; Mantovani, H C; Santos, S A

    2016-03-01

    The fermentation profile, chemical composition, and microbial populations of alfalfa silages treated with microbial inoculants (MI) at different fermentation periods (T) were evaluated in tropical conditions. A 4×6 factorial arrangement was used in a randomized design with 3 replicates. Fresh alfalfa was treated with (1) no treatment (CTRL), (2) commercial inoculant (CIN), (3) Pediococcus acidilactici (strain 10.6, S1), and (4) Pediococcus pentosaceus (strain 6.16, S2). An inoculant application rate of 10(6) cfu/g of fresh forage was used. The fermentation periods were 1, 3, 7, 14, 28, and 56 d. Alfalfa was harvested 82 d after sowing at the early flowering stage, chopped into 1.5-cm particle size, and ensiled in 25×35cm vacuum-sealed plastic bags. The numbers of lactic acid bacteria, enterobacteria, mold, and yeast in alfalfa before ensiling were 5.42, 5.58, 4.82, and 4.8 log cfu/g, respectively. Silage chemical composition was evaluated only at 56 d. All parameters were affected by the interaction MI × T, except the concentrations of lactic and propionic acids. Alfalfa silage treated with S1 or S2 had lower pH values than CTRL from the first day until 28 d. However, the inoculants resulted in similar pH after 56 d, and these values were lower than the CTRL. The highest concentration of lactic acid was observed in the silage treated with S1 and S2 at 7 and 14 d of ensiling. The concentration of acetic acid was lower in the silages treated with S1 and S2 than the CTRL and CIN at 3 and 28 d of fermentation. There was no effect of MI or MI × T interaction on the microbial populations. However, the number of enterobacteria decreased over the fermentation period until 14 d and increased slightly after this time point. The chemical composition of alfalfa silage was not affected by MI at 56 d of ensiling. The strain P. pentosaceus 6.16 was the most efficient in dominating the fermentation process by decreasing the pH more quickly and increasing the concentration of

  11. Development of the Conceptual Models for Chemical Conditions and Hydrology Used in the 1996 Performance Assessment for the Waste Isolation Pilot Plant

    SciTech Connect

    LARSON, KURT W

    2000-05-24

    The Waste Isolation Pilot Plant (WIPP) is a US Department of Energy (DOE) facility for the permanent disposal of defense-related transuranic (TRU) waste. US Environmental Protection Agency (EPA) regulations specify that the DOE must demonstrate on a sound basis that the WIPP disposal system will effectively contain long-lived alpha-emitting radionuclides within its boundaries for 10,000 years following closure. In 1996, the DOE submitted the ''40 CFR Part 191 Compliance Certification Application for the Waste Isolation Pilot Plant'' (CCA) to the EPA. The CCA proposed that the WIPP site complies with EPA's regulatory requirements. Contained within the CCA are descriptions of the scientific research conducted to characterize the properties of the WIPP site and the probabilistic performance assessment (PA) conducted to predict the containment properties of the WIPP disposal system. In May 1998, the EPA certified that the TRU waste disposal at the WIPP complies with its regulations. Waste disposal operations at WIPP commenced on March 28, 1999. The 1996 WIPP PA model of the disposal system included conceptual and mathematical representations of key hydrologic and geochemical processes. These key processes were identified over a 22-year period involving data collection, data interpretation, computer models, and sensitivity studies to evaluate the importance of uncertainty and of processes that were difficult to evaluate by other means. Key developments in the area of geochemistry were the evaluation of gas generation mechanisms in the repository; development of a model of chemical conditions in the repository and actinide concentrations in brine; selecting MgO backfill and demonstrating its effects experimentally; and determining the chemical retardation capability of the Culebra. Key developments in the area of hydrology were evacuating the potential for groundwater to dissolve the Salado Formation (the repository host formation), development of a regional model for

  12. Diffusional modification of prograde chemical zoning in garnet and its bearing on the estimates of prograde metamorphic conditions in medium to high grade rocks

    NASA Astrophysics Data System (ADS)

    Konopásek, Jiří; Caddick, Mark J.

    2016-04-01

    Preserved prograde chemical zoning in metamorphic garnet is often used for quantification of pressure and temperature conditions during its growth. However, from the time that zoning is established during growth, intra-crystalline diffusion continually acts to modify it. This operates at various rates throughout the entire metamorphic cycle and causes progressive deviation of garnet compositional profiles from those established during growth, potentially leading to large errors if these compositions are used to estimate pressure-temperature (P-T) conditions. To illustrate, we quantify the extent of compositional changes due to intra-crystalline diffusion occurring during 20 Ma of burial along 16-19°C/km geotherms followed by 1, 15 and 30 Ma of exhumation, for a pelitic sample. Typically, garnet growth in our modelling starts at c. 420°C and 5.5-7 kbar and is terminated at Tmax (600-750°C at c. 10-10.5 kbar). Calculations involve development of growth zoning (inferred from equilibrium thermodynamic modelling) and its simultaneous modification due to intra-crystalline multi-component diffusion along these prescribed paths. This allows us to quantify the extent to which zoning modification depends on crystal growth rate and size, maximum temperature achieved, and garnet composition. The use of diffusionally modified garnet compositions for thermobarometry leads to shortening of the inferred prograde pressure-temperature paths (relative to the actual path experienced) and can introduce significant errors in estimates of P-T conditions at different stages of a rock's evolution. In our model example, the conditions of earliest garnet growth would be overestimated by c. 1.5-2 kbar and c. 40-70°C for garnet crystal diameters of c. 3-5 mm in samples eventually reaching mid-amphibolite facies temperatures (or by 2-4 kbar and c. 130-180°C for crystal diameters of c. 0.2-0.5 mm). The conditions of earliest garnet growth in crystals reaching 1 mm in diameter can be

  13. Chemical evolution of RNA under hydrothermal conditions and the role of thermal copolymers of amino acids for the prebiotic degradation and formation of RNA

    NASA Astrophysics Data System (ADS)

    Kawamura, K.; Nagahama, M.; Kuranoue, K.

    The roles of thermal copolymers of amino acids (TCAA) were studied for the prebiotic degradation of RNA. A weak catalytic ability of TCAA consisted of Glu, L-Ala, L-Val, L-Glu, L-Asp, and optionally L-His was detected for the cleavage of the ribose phosphodiester bond of a tetranucleotide (5'-dCrCdGdG) in aqueous solution at 80 °C. The rate constants of the disappearance of 5'-dCrCdGdG were determined in aqueous solutions using different pH buffer and TCAA. The degradation rates were enhanced 1.3-3.0 times in the presence of TCAA at pH 7.5 and 8.0 at 80 °C, while the hydrolysis of oligoguanylate (oligo(G)) was accelerated about 1.6 times at pH 8.0. A weak inhibitory activity for the cleavage of oligo(G) was detected in the presence of 0.055 M TCAA-Std. On the other hand, our recent study on the influences of TCAA for the template-directed reaction of oligo(G) on a polycytidylic acid template showed that TCAA has an acceleration activity for the degradation of the activated nucleotide monomer and an acceleration activity for the formation of G 5' ppG capped oligo(G). This series of studies suggest that efficient and selective catalytic or inhibitory activities for either the degradation or formation of RNA under hydrothermal conditions could have hardly emerged from the simple thermal condensation products of amino acids. A scenario is going to be deduced on the chemical evolution of enzymatic activities and RNA molecules concerning hydrothermal earth conditions.

  14. Depositional conditions for the Kuna Formation, Red Dog Zn-PB-Ag-Barite District, Alaska, inferred from isotopic and chemical proxies

    USGS Publications Warehouse

    Johnson, Craig A.; Dumoulin, Julie A.; Burruss, Robert A.; Slack, John F.

    2015-01-01

    Water column redox conditions, degree of restriction of the depositional basin, and other paleoenvironmental parameters have been determined for the Mississippian Kuna Formation of northwestern Alaska from stratigraphic profiles of Mo, Fe/Al, and S isotopes in pyrite, C isotopes in organic matter, and N isotopes in bulk rock. This unit is important because it hosts the Red Dog and Anarraaq Zn-Pb-Ag ± barite deposits, which together constitute one of the largest zinc resources in the world. The isotopic and chemical proxies record a deep basin environment that became isolated from the open ocean, became increasingly reducing, and ultimately became euxinic. The basin was ventilated briefly and then became isolated again just prior to its demise as a discrete depocenter with the transition to the overlying Siksikpuk Formation. Ventilation corresponded approximately to the initiation of bedded barite deposition in the district, whereas the demise of the basin corresponded approximately to the formation of the massive sulfide deposits. The changes in basin circulation during deposition of the upper Kuna Formation may have had multiple immediate causes, but the underlying driver was probably extensional tectonic activity that also facilitated fluid flow beneath the basin floor. Although the formation of sediment-hosted sulfide deposits is generally favored by highly reducing conditions, the Zn-Pb deposits of the Red Dog district are not found in the major euxinic facies of the Kuna basin, nor did they form during the main period of euxinia. Rather, the deposits occur where strata were permeable to migrating fluids and where excess H2S was available beyond what was produced in situ by decomposition of local sedimentary organic matter. The known deposits formed mainly by replacement of calcareous strata that gained H2S from nearby highly carbonaceous beds (Anarraaq deposit) or by fracturing and vein formation in strata that produced excess H2S by reductive dissolution of

  15. Chemical evolution of RNA under hydrothermal conditions and the role of thermal copolymers of amino acids for the prebiotic degradation and formation of RNA

    NASA Technical Reports Server (NTRS)

    Kawamura, K.; Nagahama, M.; Kuranoue, K.

    2005-01-01

    The roles of thermal copolymers of amino acids (TCAA) were studied for the prebiotic degradation of RNA. A weak catalytic ability of TCAA consisted of Glu, L-Ala, L-Val, L-Glu, L-Asp, and optionally L-His was detected for the cleavage of the ribose phosphodiester bond of a tetranucleotide (5'-dCrCdGdG) in aqueous solution at 80 degees C. The rate constants of the disappearance of 5'-dCrCdGdG were determined in aqueous solutions using different pH buffer and TCAA. The degradation rates were enhanced 1.3-3.0 times in the presence of TCAA at pH 7.5 and 8.0 at 80 degrees C, while the hydrolysis of oligoguanylate (oligo(G)) was accelerated about 1.6 times at pH 8.0. A weak inhibitory activity for the cleavage of oligo(G) was detected in the presence of 0.055 M TCAA-Std. On the other hand, our recent study on the influences of TCAA for the template-directed reaction of oligo(G) on a polycytidylic acid template showed that TCAA has an acceleration activity for the degradation of the activated nucleotide monomer and an acceleration activity for the formation of G5' ppG capped oligo(G). This series of studies suggest that efficient and selective catalytic or inhibitory activities for either the degradation or formation of RNA under hydrothermal conditions could have hardly emerged from the simple thermal condensation products of amino acids. A scenario is going to be deduced on the chemical evolution of enzymatic activities and RNA molecules concerning hydrothermal earth conditions. c2005 COSPAR. Published by Elsevier Ltd. All rights reserved.

  16. Inventory of chemicals used at Hanford Site production plants and support operations (1944-1980)

    SciTech Connect

    Klem, M. J.

    1990-04-01

    A complete list of chemicals used in the production facilities and support operations of the US Department of Energy Hanford Site is presented to aid development of plans for characterizing the radioactive liquid chemical wastes stored in the 149 single-shell tanks. The complete chemical list is compared to the list provided by the regulatory agencies to identify hazardous chemicals stored in the single-shell tanks. A reduced list has been developed by others and is used to identify the chemical constituents for analysis in the Waste Characterization Plan for the Hanford Site Single-Shell Tanks. The chemical list is based on chemical process flowsheets, essential material consumption records, letters, reports, and other historical data. 14 refs., 36 tabs.

  17. Chemical geodynamics

    NASA Astrophysics Data System (ADS)

    Zindler, A.; Hart, S.

    Consideration is given to the following three principal boundary conditions relating to the nature and development of chemical structure in the earth's mantle: (1) inferred scale lengths for mantle chemical heterogeneities, (2) interrelationships of the various isotopic tracers, and (3) the bulk composition of the earth. These boundary conditions are integrated with geophysical constraints in order to evaluate models for the development of the physical and chemical structure of the mantle. Data indicate that: (1) km-size heterogeneities can survive diffusive equilibrium for billions of years; (2) the mantle is chemically heterogeneous on both very small and very large scales; (3) isotopic heterogeneities in the mantle require the existence of four 'end-member' components (DMM, HIMU, EM I, and EM II) and are consistent with the existence of at least two additional components (BSE, PREMA); and (4) primitive undepleted mantle can made up no more than about 55 percent of the total mantle.

  18. A Nontoxic Polypeptide Oligomer with a Fungicide Potency under Agricultural Conditions Which Is Equal or Greater than That of Their Chemical Counterparts

    PubMed Central

    Monteiro, Sara; Carreira, Alexandra; Freitas, Regina; Pinheiro, Ana Margarida; Ferreira, Ricardo Boavida

    2015-01-01

    There are literally hundreds of polypeptides described in the literature which exhibit fungicide activity. Tens of them have had attempted protection by patent applications but none, as far as we are aware, have found application under real agricultural conditions. The reasons behind may be multiple where the sensitivity to the Sun UV radiation can come in first place. Here we describe a multifunctional glyco-oligomer with 210 kDa which is mainly composed by a 20 kDa polypeptide termed Blad that has been previously shown to be a stable intermediary product of β-conglutin catabolism. This oligomer accumulates exclusively in the cotyledons of Lupinus species, between days 4 and 12 after the onset of germination. Blad-oligomer reveals a plethora of biochemical properties, like lectin and catalytic activities, which are not unusual per si, but are remarkable when found to coexist in the same protein molecule. With this vast range of chemical characteristics, antifungal activity arises almost as a natural consequence. The biological significance and potential technological applications of Blad-oligomer as a plant fungicide to agriculture, its uniqueness stems from being of polypeptidic in nature, and with efficacies which are either equal or greater than the top fungicides currently in the market are addressed. PMID:25849076

  19. AlN thin films prepared by ArF plasma assisted PLD. Role of process conditions on electronic and chemical-morphological properties

    NASA Astrophysics Data System (ADS)

    Cappelli, E.; Trucchi, D. M.; Orlando, S.; Valentini, V.; Mezzi, A.; Kaciulis, S.

    2014-02-01

    Aluminium nitride thin films were deposited on n-Si <100> substrates by RF plasma activated reactive pulsed laser deposition (PLD). An ArF excimer pulsed laser, 10 Hz and 2.5 J/cm2 energy fluence, has been used to ablate a pure Al target in a reactive atmosphere of N2 plasma (generated by a RF source), at varying processing parameters (substrate temperature, time, and N2 plasma configuration). We studied the dependence and correlation of structural and electronic properties with the experimental conditions. The chemical composition of deposited material has been determined by both Raman and X-ray photoelectron spectroscopy (XPS). Electrical resistivity has been evaluated by the sheet resistance method. Both spectroscopic characterizations (Raman and XPS) show a strong dependence in the formation of AlN on the deposition temperature. At low temperatures, there is little formation of nitride, with a prevalence of aluminium oxide, while at higher temperatures the N uptake increases, with AlN formation. Raman analysis also highlights the formation of nano-structures, for temperatures ≥400∘C. These material characteristics have a fundamental influence on the electronic properties. Indeed, electrical resistivity properties have been found to be strongly dependent on the film structure, nitrogen incorporation, and presence of mixed oxide compounds, closely related to deposition temperature.

  20. Spectroscopic studies of the effect of aerobic conditions on the chemical characteristics of humic acid in landfill leachate and its implication for the environment.

    PubMed

    Xiaoli, Chai; Yongxia, Hao; Guixiang, Liu; Xin, Zhao; Youcai, Zhao

    2013-05-01

    Humic acids (HAs) that extracted from leachates from semi-aerobic and anaerobic landfills test field at different stabilization times were characterized by elemental composition, Fourier transform infrared spectroscopy (FTIR), and Carbon-13 Cross-Polarization Magic-Angle-Spinning Nuclear Magnetic Resonance ((13)C CP/MAS NMR). The higher sulfur (S) content of HA in the anaerobic landfill leachate after a short stabilization time showed that the S released from the organic matter degradation was more easily stabilized under anaerobic conditions, which indicate that HA from anaerobic landfill leachate was more chemically reactive and played a more important role in mobilizing heavy metal, especially mercury, at early landfill stabilization times. However, the S content of HA from the semi-aerobic landfill increased over time, suggesting that more S was stabilized in HA as the landfill stabilization time was extended. The analytical results for the FTIR and NMR showed that the HA from the anaerobic landfill contained more aromatic groups, while HA from the semi-aerobic landfill had more oxygen-containing groups. The aromatic components of the HA from both the anaerobic and semi-aerobic landfills increased over time, suggesting that the maturity and humification degree of HA increased during the stabilization process. PMID:23461837

  1. 129Xe NMR chemical shift in Xe@C60 calculated at experimental conditions: essential role of the relativity, dynamics, and explicit solvent.

    PubMed

    Standara, Stanislav; Kulhánek, Petr; Marek, Radek; Straka, Michal

    2013-08-15

    The isotropic (129)Xe nuclear magnetic resonance (NMR) chemical shift (CS) in Xe@C60 dissolved in liquid benzene was calculated by piecewise approximation to faithfully simulate the experimental conditions and to evaluate the role of different physical factors influencing the (129)Xe NMR CS. The (129)Xe shielding constant was obtained by averaging the (129)Xe nuclear magnetic shieldings calculated for snapshots obtained from the molecular dynamics trajectory of the Xe@C60 system embedded in a periodic box of benzene molecules. Relativistic corrections were added at the Breit-Pauli perturbation theory (BPPT) level, included the solvent, and were dynamically averaged. It is demonstrated that the contribution of internal dynamics of the Xe@C60 system represents about 8% of the total nonrelativistic NMR CS, whereas the effects of dynamical solvent add another 8%. The dynamically averaged relativistic effects contribute by 9% to the total calculated (129)Xe NMR CS. The final theoretical value of 172.7 ppm corresponds well to the experimental (129)Xe CS of 179.2 ppm and lies within the estimated errors of the model. The presented computational protocol serves as a prototype for calculations of (129)Xe NMR parameters in different Xe atom guest-host systems. PMID:23703381

  2. Mobility of major and trace elements in andosols from Iceland: correlating extent of chemical weathering with climatic conditions at soil formation sites

    NASA Astrophysics Data System (ADS)

    Oskarsson, Birgir V.; Riishuus, Morten S.; Arnalds, Olafur

    2010-05-01

    Element mobility within volcanic soil profiles developed in diverse climatic conditions in Iceland is assessed. Soils were selected from areas with good monitoring of annual temperature and precipitation and the degree of weathering and elemental behavior was compared. Most soils in Iceland develop in parent materials of volcanic origin, including a variety of basaltic and andesitic tephras, hyaloclastites and glacial tillites. Most Icelandic soils are subject to considerable flux of eolian deposition and in times receive tephra ejecta from volcanic eruptions. In this study, samples were carefully extracted from brown and gleyic andosol horizons for major and trace element analysis. Each horizon is representative of a pedogenetic stage. Preliminary results show that the major elements TiO2, Al2O3 and Fe2O3 (T) (mean wt% = 3.4, 19.2, 17.3) appear immobile relative to the parent material (p.m. mean wt% = 1.6, 14.6, 10.9) and are found enriched within more mature horizons. The base cations MgO, CaO and Na2O (mean wt% = 4.11, 7.23, 1.8) are depleted in these horizons (p.m. mean wt% = 9.1, 11.8, 2.0) showing mobilization during pedogenesis. The trace elements reveal no strong enrichment/depletion trend with a range of mobility from mobile to immobile Rb, Zn, Y, Sr, Ba, Ni, La, Cr, Cu, Nd, V, Zr and Nb. Soils developed in colder and dryer climatic conditions in Iceland (MAT = -1°C and MAP = 1000mm) show higher levels of weathering (CIA-K = 50-65) and element mobilization. The parent materials have a CIA-K weathering index of 37. The relationship of the covariance of the climate parameters with extent of chemical weathering may be quantified as climofunctions to deliver proxy climate data under cool to subarctic conditions. Our results may yield reasonable tools for determining past climate variations from weathered tephras found as paleosols in the Neogene lava piles of Iceland and other volcanic provinces.

  3. The chemical conditions of the late Archean Hamersley basin inferred from whole rock and pyrite geochemistry with Δ33S and δ34S isotope analyses

    NASA Astrophysics Data System (ADS)

    Gregory, Daniel D.; Large, Ross R.; Halpin, Jacqueline A.; Steadman, Jeffery A.; Hickman, Arthur H.; Ireland, Trevor R.; Holden, Peter

    2015-01-01

    The well-preserved late Archean sedimentary rocks of the Fortescue and Hamersley Basins in Western Australia offer fascinating insights into early earth ocean chemistry prior to the Great Oxidation Event (GOE). In this study, we use a combination of whole rock geochemistry, LA-ICPMS trace element analysis of sedimentary pyrite and pyrrhotite and SHRIMP-SI sulfur isotope analyses to elucidate the chemical changes in these sedimentary rocks. These proxies are used to examine chemical conditions of the ocean during the late Archean. Two to three periods of oxygen enrichment prior to the deposition of banded iron formations (BIF) can be identified. One minor stage of general increase in whole rock enrichment factors and trace element content of pyrite is observed up stratigraphy in the Jeerinah Formation, Fortescue Basin and a more substantial stage is present in the Paraburdoo and Bee Gorge Members of the Wittenoom Formation, Hamersley Basin. Some of the trace element enrichments indicate organic matter burial flux (Ni, Cr, Zn, Co and Cu) which suggests an increase in biological productivity. If the increased biological activity reflects an increase in cyanobacteria activity then an associated increase in oxygen is likely to have occurred during the deposition of the Bee Gorge Member. An increase in atmospheric oxygen would result in continental weathering of sulfide and other minerals, increasing the trace element content of the water column via erosion and avoiding excessive depletion of trace elements due to drawdown in seawater. Since some of these trace elements may also be limiting nutrients (such as Mo and Se) for the cyanobacteria, the degree of biological productivity may have further increased due to the increasing amount of trace elements introduced by oxygenation in a positive feedback loop. These periods of increased productivity and oxygen rise stopped prior to the onset of BIF deposition in the Hamersley Basin. This may be due to the ocean reaching an

  4. Determination of chemical-constituent loads during base-flow and storm-runoff conditions near historical mines in Prospect Gulch, upper Animas River watershed, southwestern Colorado

    USGS Publications Warehouse

    Wirt, Laurie; Leib, K.J.; Bove, D.J.; Mast, M.A.; Evans, J.B.; Meeker, G.P.

    1999-01-01

    Prospect Gulch is a major source of iron, aluminum, zinc, and other metals to Cement Creek. Information is needed to prioritize remediation and develop strategies for cleanup of historical abandoned mine sites in Prospect Gulch. Chemical-constituent loads were determined in Prospect Gulch, a high-elevation alpine stream in southwestern Colorado that is affected by natural acid drainage from weathering of hydro-thermally altered igneous rock and acidic metal-laden discharge from historical abandoned mines. The objective of the study was to identify metal sources to Prospect Gulch. A tracer solution was injected into Prospect Gulch during water-quality sampling so that loading of geochemical constituents could be calculated throughout the study reach. A thunderstorm occurred during the tracer study, hence, metal loads were measured for storm-runoff as well as for base flow. Data from different parts of the study reach represents different flow conditions. The beginning of the reach represents background conditions during base flow immediately upstream from the Lark and Henrietta mines (samples PG5 to PG45). Other samples were collected during storm runoff conditions (PG100 to PG291); during the first flush of metal runoff following the onset of rainfall (PG303 to PG504), and samples PG542 to PG700 were collected during low-flow conditions. During base-flow conditions, the percentage increase in loads for major constituents and trace metals was more than an order of magnitude greater than the corresponding 36 % increase in stream discharge. Within the study reach, the highest percentage increases for dissolved loads were 740 % for iron (Fe), 465 % for aluminum (Al), 500 % for lead (Pb), 380 % for copper (Cu), 100 % for sulfate (SO4), and 50 % for zinc (Zn). Downstream loads near the mouth of Prospect Gulch often greatly exceeded the loads generated within the study reach but varied by metal species. For example, the study reach accounts for about 6 % of the dissolved

  5. Chemical and mineralogical data and processing methods management system prototype with application to study of the North Caucasus Blybsky Metamorphic Complexes metamorphism PT-condition

    NASA Astrophysics Data System (ADS)

    Ivanov, Stanislav; Kamzolkin, Vladimir; Konilov, Aleksandr; Aleshin, Igor

    2014-05-01

    There are many various methods of assessing the conditions of rocks formation based on determining the composition of the constituent minerals. Our objective was to create a universal tool for processing mineral's chemical analysis results and solving geothermobarometry problems by creating a database of existing sensors and providing a user-friendly standard interface. Similar computer assisted tools are based upon large collection of sensors (geothermometers and geobarometers) are known, for example, the project TPF (Konilov A.N., 1999) - text-based sensor collection tool written in PASCAL. The application contained more than 350 different sensors and has been used widely in petrochemical studies (see A.N. Konilov , A.A. Grafchikov, V.I. Fonarev 2010 for review). Our prototype uses the TPF project concept and is designed with modern application development techniques, which allows better flexibility. Main components of the designed system are 3 connected datasets: sensors collection (geothermometers, geobarometers, oxygen geobarometers, etc.), petrochemical data and modeling results. All data is maintained by special management and visualization tools and resides in sql database. System utilities allow user to import and export data in various file formats, edit records and plot graphs. Sensors database contains up to date collections of known methods. New sensors may be added by user. Measured database should be filled in by researcher. User friendly interface allows access to all available data and sensors, automates routine work, reduces the risk of common user mistakes and simplifies information exchange between research groups. We use prototype to evaluate peak pressure during the formation of garnet-amphibolite apoeclogites, gneisses and schists Blybsky metamorphic complex of the Front Range of the Northern Caucasus. In particular, our estimation of formation pressure range (18 ± 4 kbar) agrees on independent research results. The reported study was

  6. Differential biofilm formation and chemical disinfection resistance of sessile cells of Listeria monocytogenes strains under monospecies and dual-species (with Salmonella enterica) conditions.

    PubMed

    Kostaki, Maria; Chorianopoulos, Nikos; Braxou, Elli; Nychas, George-John; Giaouris, Efstathios

    2012-04-01

    This study aimed to investigate the possible influence of bacterial intra- and interspecies interactions on the ability of Listeria monocytogenes and Salmonella enterica to develop mixed-culture biofilms on an abiotic substratum, as well as on the subsequent resistance of sessile cells to chemical disinfection. Initially, three strains from each species were selected and left to attach and form biofilms on stainless steel (SS) coupons incubated at 15°C for 144 h, in periodically renewable tryptone soy broth (TSB), under either monoculture or mixed-culture (mono-/dual-species) conditions. Following biofilm formation, mixed-culture sessile communities were subjected to 6-min disinfection treatments with (i) benzalkonium chloride (50 ppm), (ii) sodium hypochlorite (10 ppm), (iii) peracetic acid (10 ppm), and (iv) a mixture of hydrogen peroxide (5 ppm) and peracetic acid (5 ppm). Results revealed that both species reached similar biofilm counts (ca. 10(5) CFU cm(-2)) and that, in general, interspecies interactions did not have any significant effect either on the biofilm-forming ability (as this was assessed by agar plating enumeration of the mechanically detached biofilm bacteria) or on the antimicrobial resistance of each individual species. Interestingly, pulsed-field gel electrophoresis (PFGE) analysis clearly showed that the three L. monocytogenes strains did not contribute at the same level either to the formation of mixed-culture sessile communities (mono-/dual species) or to their antimicrobial recalcitrance. Additionally, the simultaneous existence inside the biofilm structure of S. enterica cells seemed to influence the occurrence and resistance pattern of L. monocytogenes strains. In sum, this study highlights the impact of microbial interactions taking place inside a mixed-culture sessile community on both its population dynamics and disinfection resistance. PMID:22307304

  7. Differential Biofilm Formation and Chemical Disinfection Resistance of Sessile Cells of Listeria monocytogenes Strains under Monospecies and Dual-Species (with Salmonella enterica) Conditions

    PubMed Central

    Kostaki, Maria; Chorianopoulos, Nikos; Braxou, Elli; Nychas, George-John

    2012-01-01

    This study aimed to investigate the possible influence of bacterial intra- and interspecies interactions on the ability of Listeria monocytogenes and Salmonella enterica to develop mixed-culture biofilms on an abiotic substratum, as well as on the subsequent resistance of sessile cells to chemical disinfection. Initially, three strains from each species were selected and left to attach and form biofilms on stainless steel (SS) coupons incubated at 15°C for 144 h, in periodically renewable tryptone soy broth (TSB), under either monoculture or mixed-culture (mono-/dual-species) conditions. Following biofilm formation, mixed-culture sessile communities were subjected to 6-min disinfection treatments with (i) benzalkonium chloride (50 ppm), (ii) sodium hypochlorite (10 ppm), (iii) peracetic acid (10 ppm), and (iv) a mixture of hydrogen peroxide (5 ppm) and peracetic acid (5 ppm). Results revealed that both species reached similar biofilm counts (ca. 105 CFU cm−2) and that, in general, interspecies interactions did not have any significant effect either on the biofilm-forming ability (as this was assessed by agar plating enumeration of the mechanically detached biofilm bacteria) or on the antimicrobial resistance of each individual species. Interestingly, pulsed-field gel electrophoresis (PFGE) analysis clearly showed that the three L. monocytogenes strains did not contribute at the same level either to the formation of mixed-culture sessile communities (mono-/dual species) or to their antimicrobial recalcitrance. Additionally, the simultaneous existence inside the biofilm structure of S. enterica cells seemed to influence the occurrence and resistance pattern of L. monocytogenes strains. In sum, this study highlights the impact of microbial interactions taking place inside a mixed-culture sessile community on both its population dynamics and disinfection resistance. PMID:22307304

  8. Volatile chemical spoilage indexes of raw Atlantic salmon (Salmo salar) stored under aerobic condition in relation to microbiological and sensory shelf lives.

    PubMed

    Mikš-Krajnik, Marta; Yoon, Yong-Jin; Ukuku, Dike O; Yuk, Hyun-Gyun

    2016-02-01

    The purpose of this investigation was to identify and quantify the volatile chemical spoilage indexes (CSIs) for raw Atlantic salmon (Salmo salar) fillets stored under aerobic storage conditions at 4, 10 and 21 °C in relation to microbial and sensory shelf lives. The volatile organic compounds (VOCs) were analyzed with SPME-GC-MS technique. Through multivariate chemometric method, hierarchical cluster analysis (HCA) and Pearson's correlations, the CSIs: trimethylamine (TMA), ethanol (EtOH), 3-methyl-1-butanol (3Met-1But), acetoin and acetic acid (C2) were selected from the group of 28 detected VOCs. At the moment of microbiological shelf life established at total viable count (TVC) of 7.0 log CFU/g, the CSIs achieved levels of 11.5, 38.3, 0.3, 24.0 and 90.7 μg/g of salmon for TMA, EtOH, 3M-1But, acetoin and C2, respectively. Pseudomonas spp. was found as major specific spoilage organism (SSOs), suitable for shelf life prediction using modified Gompertz model at the cut-off level of 6.5 log CFU/g. H2S producing bacteria and Brochothrix thermosphacta were considered as important spoilage microorganisms; however, they were not suitable for shelf life estimation. Partial least square (PLS) regression revealed possible associations between microorganisms and synthetized VOCs, showing correlations between Pseudomonas spp. and 3Met-1But and aldehydes synthesis, lactic acid bacteria were linked with EtOH, C2 and esters, and B. thermosphacta with acetoin formation. PMID:26678146

  9. Modelling the growth/no growth boundary of Zygosaccharomyces bailii in acidic conditions: a contribution to the alternative method to preserve foods without using chemical preservatives.

    PubMed

    Dang, T D T; Mertens, L; Vermeulen, A; Geeraerd, A H; Van Impe, J F; Debevere, J; Devlieghere, F

    2010-01-31

    The aim of the study was to develop mathematical models describing growth/no growth (G/NG) boundaries of the highly resistant food spoilage yeast-Zygosaccharomyces bailii-in different environmental conditions, taking acidified sauces as the target product. By applying these models, the stability of products with characteristics within the investigated pH, a(w) and acetic acid ranges can be evaluated. Besides, the well-defined no growth regions can be used in the development of guidelines regarding formulation of new shelf-stable foods without using chemical preservatives, which would facilitate the innovation of additive-free products. Experiments were performed at different temperatures and periods (22 degrees C for 45 and 60days, 30 degrees C for 45days) in 150 modified Sabouraud media characterized by high amount of sugars (glucose and fructose, 15% (w/v)), acetic acid (0.0-2.5% (v/v), 6 levels), pH (3.0-5.0, 5 levels) and a(w) (0.93-0.97, 5 levels). These time and temperature combinations were chosen as they are commonly applied for shelf-stable foods. The media were inoculated with ca. 4.5 log CFU/ml and yeast growth was monitored daily using optical density measurements. Every condition was examined in 20 replicates in order to yield accurate growth probabilities. Three separate ordinary logistic regression models were developed for different tested temperatures and incubation time. The total acetic acid concentration was considered as variable for all models. In general, when one intrinsic inhibitory factor became more stringent, the G/NG boundary shifted to less stressful conditions of the other two factors, resulting in enlarged no growth zones. Abrupt changes of growth probability often occurred around the transition zones (between growth and no growth regions), which indicates that minor variations in environmental conditions near the G/NG boundaries can cause a significant impact on the growth probability. When comparing growth after 45days between the

  10. Alkali Activated Systems: Understanding the Influence of Curing Conditions and Activator Type/Chemistry on the Mechanical Strength and Chemical Structure of Fly Ash/Slag Systems

    NASA Astrophysics Data System (ADS)

    Chowdhury, Ussala

    The alkali activation of aluminosilicate materials as binder systems derived from industrial byproducts have been extensively studied due to the advantages they offer in terms enhanced material properties, while increasing sustainability by the reuse of industrial waste and byproducts and reducing the adverse impacts of OPC production. Fly ash and ground granulated blast furnace slag are commonly used for their content of soluble silica and aluminate species that can undergo dissolution, polymerization with the alkali, condensation on particle surfaces and solidification. The following topics are the focus of this thesis: (i) the use of microwave assisted thermal processing, in addition to heat-curing as a means of alkali activation and (ii) the relative effects of alkali cations (K or Na) in the activator (powder activators) on the mechanical properties and chemical structure of these systems. Unsuitable curing conditions instigate carbonation, which in turn lowers the pH of the system causing significant reductions in the rate of fly ash activation and mechanical strength development. This study explores the effects of sealing the samples during the curing process, which effectively traps the free water in the system, and allows for increased aluminosilicate activation. The use of microwave-curing in lieu of thermal-curing is also studied in order to reduce energy consumption and for its ability to provide fast volumetric heating. Potassium-based powder activators dry blended into the slag binder system is shown to be effective in obtaining very high compressive strengths under moist curing conditions (greater than 70 MPa), whereas sodium-based powder activation is much weaker (around 25 MPa). Compressive strength decreases when fly ash is introduced into the system. Isothermal calorimetry is used to evaluate the early hydration process, and to understand the reaction kinetics of the alkali powder activated systems. A qualitative evidence of the alkali

  11. From Common Sense Concepts to Scientifically Conditioned Concepts of Chemical Bonding: An Historical and Textbook Approach Designed to Address Learning and Teaching Issues at the Secondary School Level

    ERIC Educational Resources Information Center

    Croft, Michael; de Berg, Kevin

    2014-01-01

    This paper selects six key alternative conceptions identified in the literature on student understandings of chemical bonding and illustrates how a historical analysis and a textbook analysis can inform these conceptions and lead to recommendations for improving the teaching and learning of chemical bonding at the secondary school level. The…

  12. Physico-chemical conditions of crystallization of the Guli ulrabasic massif (North Part of the Siberian Platform): evidence from melt inclusions

    NASA Astrophysics Data System (ADS)

    Simonov, Vladimir; Vasiliev, Yuri; Kotlyarov, Alexey; Stupakov, Sergey

    2014-05-01

    Conditions of formation of the Guli ultrabasic massif (Maimecha Kotui Province in the North Part of the Siberian Platform) attract attention of numerous researchers. For the solution of genetic problems of various rocks from this ultramafic complex the data on melt inclusions in minerals has been earlier used (Sokolov et al., 1999; Rass, Plechov, 2000; Sokolov, 2003; Panina, 2006). At the same time, formation of dunites, occupying the main volume of the Guli massif, remain almost not considered by means of thermobarogeochemical methods and the role of magmatic processes in this case is not ascertained. As a result of melt inclusions study in the Cr-spinel the new data on physical and chemical parameters of dunite crystallization in the Guli ulrabasic massif was obtained. On the ratio (Na2O + K2O) - SiO2 the majority of analyses of glasses and calculated compositions of inclusions settle down in the field of subalkaline series. On the diagram MgO - SiO2 bulk chemical compositions of inclusions (with the magnesium content of 19-28 wt. %) correspond to picrites and picrite-basalts. They are in close association with the data on inclusions in the Cr-spinel from dunites of Konder (Siberian Platform) and Nizhnii Tagil (Ural Mountains) platinum-bearing ultrabasic massifs and also are situated near to the field of inclusions in the olivine phenocrysts from meimechites (Maimecha Kotui Province in the North Part of the Siberian Platform). Similarity of melt inclusions in the Cr-spinel from the dunite of the Guli massif and in the olivine from meimechites is established on the variety of petrochemical components - Al2O3, CaO, Na2O, K2O. The calculated compositions of inclusions from dunites coincide mostly with the data on inclusions from meimechites, while glasses of inclusions from Cr-spinel contain less titan and magnesium. As a whole for the melts of the Maimecha Kotui Province (that form both dunites of the Guli massif and meimechites) much higher contents of TiO2 (from

  13. Evaluation of alternative chemical additives for high-level waste vitrification feed preparation processing

    SciTech Connect

    Seymour, R.G.

    1995-06-07

    During the development of the feed processing flowsheet for the Defense Waste Processing Facility (DWPF) at the Savannah River Site (SRS), research had shown that use of formic acid (HCOOH) could accomplish several processing objectives with one chemical addition. These objectives included the decomposition of tetraphenylborate, chemical reduction of mercury, production of acceptable rheological properties in the feed slurry, and controlling the oxidation state of the glass melt pool. However, the DEPF research had not shown that some vitrification slurry feeds had a tendency to evolve hydrogen (H{sub 2}) and ammonia (NH{sub 3}) as the result of catalytic decomposition of CHOOH with noble metals (rhodium, ruthenium, palladium) in the feed. Testing conducted at Pacific Northwest Laboratory and later at the Savannah River Technical Center showed that the H{sub 2} and NH{sub 3} could evolve at appreciable rates and quantities. The explosive nature of H{sub 2} and NH{sub 3} (as ammonium nitrate) warranted significant mitigation control and redesign of both facilities. At the time the explosive gas evolution was discovered, the DWPF was already under construction and an immediate hardware fix in tandem with flowsheet changes was necessary. However, the Hanford Waste Vitrification Plant (HWVP) was in the design phase and could afford to take time to investigate flowsheet manipulations that could solve the problem, rather than a hardware fix. Thus, the HWVP began to investigate alternatives to using HCOOH in the vitrification process. This document describes the selection, evaluation criteria, and strategy used to evaluate the performance of the alternative chemical additives to CHOOH. The status of the evaluation is also discussed.

  14. Boundary conditions for the paleoenvironment: Chemical and physical processes in the pre-solar nebula. [molecular clouds, interstellar matter, and abundance

    NASA Technical Reports Server (NTRS)

    Irvine, W. M.; Schloerb, F. P.

    1985-01-01

    Two additional hyperfine components of the interstellar radical C3H were detected. In addition, methanol was discovered in interstellar clouds. The abundance of HCCN and various chemical isomers in molecular clouds was investigated.

  15. Chemical characterization of biogenic secondary organic aerosol generated from plant emissions under baseline and stressed conditions: inter- and intra-species variability for six coniferous species

    NASA Astrophysics Data System (ADS)

    Faiola, C. L.; Wen, M.; VanReken, T. M.

    2015-04-01

    The largest global source of secondary organic aerosol (SOA) in the atmosphere is derived from the oxidation of biogenic emissions. Plant stressors associated with a changing environment can alter both the quantity and composition of the compounds that are emitted. Alterations to the biogenic volatile organic compound (BVOC) profile could impact the characteristics of the SOA formed from those emissions. This study investigated the impacts of one global change stressor, increased herbivory, on the composition of SOA derived from real plant emissions. Herbivory was simulated via application of methyl jasmonate (MeJA), a proxy compound. Experiments were repeated under pre- and post-treatment conditions for six different coniferous plant types. Volatile organic compounds (VOCs) emitted from the plants were oxidized to form SOA via dark ozone-initiated chemistry. The SOA chemical composition was measured using a Aerodyne high-resolution time-of-flight aerosol mass spectrometer (HR-AMS). The aerosol mass spectra of pre-treatment biogenic SOA from all plant types tended to be similar with correlations usually greater than or equal to 0.90. The presence of a stressor produced characteristic differences in the SOA mass spectra. Specifically, the following m/z were identified as a possible biogenic stress AMS marker with the corresponding HR ion(s) shown in parentheses: m/z 31 (CH3O+), m/z 58 (C2H2O2+, C3H6O+), m/z 29 (C2H5+), m/z 57 (C3H5O+), m/z 59 (C2H3O2+, C3H7O+), m/z 71 (C3H3O2+, C4H7O+), and m/z 83 (C5H7O+). The first aerosol mass spectrum of SOA generated from the oxidation of the plant stress hormone, MeJA, is also presented. Elemental analysis results demonstrated an O : C range of baseline biogenic SOA between 0.3 and 0.47. The O : C of standard MeJA SOA was 0.52. Results presented here could be used to help identify a biogenic plant stress marker in ambient data sets collected in forest environments.

  16. Chemical characterization of biogenic SOA generated from plant emissions under baseline and stressed conditions: inter- and intra-species variability for six coniferous species

    NASA Astrophysics Data System (ADS)

    Faiola, C. L.; Wen, M.; VanReken, T. M.

    2014-10-01

    The largest global source of secondary organic aerosol in the atmosphere is derived from the oxidation of biogenic emissions. Plant stressors associated with a changing environment can alter both the quantity and composition of the compounds that are emitted. Alterations to the biogenic VOC profile could impact the characteristics of the SOA formed from those emissions. This study investigated the impacts of one global change stressor, increased herbivory, on the composition of SOA derived from real plant emissions. Herbivory was simulated via application of methyl jasmonate, a proxy compound. Experiments were repeated under pre- and post-treatment conditions for six different coniferous plant types. VOCs emitted from the plants were oxidized to form SOA via dark ozone-initiated chemistry. The SOA particle size distribution and chemical composition were measured using a scanning mobility particle sizer (SMPS) and Aerodyne high-resolution time-of-flight aerosol mass spectrometer (HR-AMS), respectively. The aerosol mass spectra of pre-treatment biogenic SOA from all plant types tended to be similar with correlations usually greater than or equal to 0.90. The presence of a stressor produced characteristic differences in the SOA mass spectra. Specifically, the following m/z were identified as a possible biogenic stress AMS marker with the corresponding HR ion(s) shown in parentheses: m/z 31 (CH3O+), m/z 58 (C2H2O2+, C3H6O+) m/z 29 (C2H5+), m/z 57 (C3H5O+), m/z 59 (C2H3O2+, C3H7O+), m/z 71 (C3H3O2+, C4H7O+), and m/z 83 (C5H7O+). The first aerosol mass spectrum of SOA generated from the oxidation of the plant stress hormone, methyl jasmonate, is also presented. Elemental analysis results demonstrated an O:C range of baseline biogenic SOA between 0.3-0.47. The O:C of standard methyl jasmonate SOA was 0.52. Results presented here could be used to help identify a biogenic plant stress marker in ambient datasets collected in forest environments.

  17. Chemical characterization of biogenic SOA generated from plant emissions under baseline and stressed conditions: inter- and intra-species variability for six coniferous species

    DOE PAGESBeta

    Faiola, C. L.; Wen, M.; VanReken, T. M.

    2014-10-01

    The largest global source of secondary organic aerosol in the atmosphere is derived from the oxidation of biogenic emissions. Plant stressors associated with a changing environment can alter both the quantity and composition of the compounds that are emitted. Alterations to the biogenic VOC profile could impact the characteristics of the SOA formed from those emissions. This study investigated the impacts of one global change stressor, increased herbivory, on the composition of SOA derived from real plant emissions. Herbivory was simulated via application of methyl jasmonate, a proxy compound. Experiments were repeated under pre- and post-treatment conditions for six differentmore » coniferous plant types. VOCs emitted from the plants were oxidized to form SOA via dark ozone-initiated chemistry. The SOA particle size distribution and chemical composition were measured using a scanning mobility particle sizer (SMPS) and Aerodyne high-resolution time-of-flight aerosol mass spectrometer (HR-AMS), respectively. The aerosol mass spectra of pre-treatment biogenic SOA from all plant types tended to be similar with correlations usually greater than or equal to 0.90. The presence of a stressor produced characteristic differences in the SOA mass spectra. Specifically, the following m/z were identified as a possible biogenic stress AMS marker with the corresponding HR ion(s) shown in parentheses: m/z 31 (CH3O+), m/z 58 (C2H2O2+, C3H6O+) m/z 29 (C2H5+), m/z 57 (C3H5O+), m/z 59 (C2H3O2+, C3H7O+), m/z 71 (C3H3O2+, C4H7O+), and m/z 83 (C5H7O+). The first aerosol mass spectrum of SOA generated from the oxidation of the plant stress hormone, methyl jasmonate, is also presented. Elemental analysis results demonstrated an O:C range of baseline biogenic SOA between 0.3–0.47. The O:C of standard methyl jasmonate SOA was 0.52. Results presented here could be used to help identify a biogenic plant stress marker in ambient datasets collected in forest environments.« less

  18. Chemical characterization of biogenic secondary organic aerosol generated from plant emissions under baseline and stressed conditions: inter- and intra-species variability for six coniferous species

    DOE PAGESBeta

    Faiola, C. L.; Wen, M.; VanReken, T. M.

    2015-04-01

    The largest global source of secondary organic aerosol (SOA) in the atmosphere is derived from the oxidation of biogenic emissions. Plant stressors associated with a changing environment can alter both the quantity and composition of the compounds that are emitted. Alterations to the biogenic volatile organic compound (BVOC) profile could impact the characteristics of the SOA formed from those emissions. This study investigated the impacts of one global change stressor, increased herbivory, on the composition of SOA derived from real plant emissions. Herbivory was simulated via application of methyl jasmonate (MeJA), a proxy compound. Experiments were repeated under pre- andmore » post-treatment conditions for six different coniferous plant types. Volatile organic compounds (VOCs) emitted from the plants were oxidized to form SOA via dark ozone-initiated chemistry. The SOA chemical composition was measured using a Aerodyne high-resolution time-of-flight aerosol mass spectrometer (HR-AMS). The aerosol mass spectra of pre-treatment biogenic SOA from all plant types tended to be similar with correlations usually greater than or equal to 0.90. The presence of a stressor produced characteristic differences in the SOA mass spectra. Specifically, the following m/z were identified as a possible biogenic stress AMS marker with the corresponding HR ion(s) shown in parentheses: m/z 31 (CH3O+), m/z 58 (C2H2O2+, C3H6O+), m/z 29 (C2H5+), m/z 57 (C3H5O+), m/z 59 (C2H3O2+, C3H7O+), m/z 71 (C3H3O2+, C4H7O+), and m/z 83 (C5H7O+). The first aerosol mass spectrum of SOA generated from the oxidation of the plant stress hormone, MeJA, is also presented. Elemental analysis results demonstrated an O : C range of baseline biogenic SOA between 0.3 and 0.47. The O : C of standard MeJA SOA was 0.52. Results presented here could be used to help identify a biogenic plant stress marker in ambient data sets collected in forest environments.« less

  19. Sensitivity to grid resolution in the ability of a chemical transport model to simulate observed oxidant chemistry under high-isoprene conditions

    NASA Astrophysics Data System (ADS)

    Yu, Karen; Jacob, Daniel J.; Fisher, Jenny A.; Kim, Patrick S.; Marais, Eloise A.; Miller, Christopher C.; Travis, Katherine R.; Zhu, Lei; Yantosca, Robert M.; Sulprizio, Melissa P.; Cohen, Ron C.; Dibb, Jack E.; Fried, Alan; Mikoviny, Tomas; Ryerson, Thomas B.; Wennberg, Paul O.; Wisthaler, Armin

    2016-04-01

    Formation of ozone and organic aerosol in continental atmospheres depends on whether isoprene emitted by vegetation is oxidized by the high-NOx pathway (where peroxy radicals react with NO) or by low-NOx pathways (where peroxy radicals react by alternate channels, mostly with HO2). We used mixed layer observations from the SEAC4RS aircraft campaign over the Southeast US to test the ability of the GEOS-Chem chemical transport model at different grid resolutions (0.25° × 0.3125°, 2° × 2.5°, 4° × 5°) to simulate this chemistry under high-isoprene, variable-NOx conditions. Observations of isoprene and NOx over the Southeast US show a negative correlation, reflecting the spatial segregation of emissions; this negative correlation is captured in the model at 0.25° × 0.3125° resolution but not at coarser resolutions. As a result, less isoprene oxidation takes place by the high-NOx pathway in the model at 0.25° × 0.3125° resolution (54 %) than at coarser resolution (59 %). The cumulative probability distribution functions (CDFs) of NOx, isoprene, and ozone concentrations show little difference across model resolutions and good agreement with observations, while formaldehyde is overestimated at coarse resolution because excessive isoprene oxidation takes place by the high-NOx pathway with high formaldehyde yield. The good agreement of simulated and observed concentration variances implies that smaller-scale non-linearities (urban and power plant plumes) are not important on the regional scale. Correlations of simulated vs. observed concentrations do not improve with grid resolution because finer modes of variability are intrinsically more difficult to capture. Higher model resolution leads to decreased conversion of NOx to organic nitrates and increased conversion to nitric acid, with total reactive nitrogen oxides (NOy) changing little across model resolutions. Model concentrations in the lower free troposphere are also insensitive to grid resolution. The

  20. Aspen Process Flowsheet Simulation Model of a Battelle Biomass-Based Gasification, Fischer-Tropsch Liquefaction and Combined-Cycle Power Plant

    SciTech Connect

    1998-10-30

    This study was done to support the research and development program of the National Renewable Energy Laboratory (NREL) in the thermochemical conversion of biomass to liquid transportation fuels using current state-of-the-art technology. The Mitretek study investigated the use of two biomass gasifiers; the RENUGAS gasifier being developed by the Institute of Gas Technology, and the indirectly heated gasifier being developed by Battelle Columbus. The Battelle Memorial Institute of Columbus, Ohio indirectly heated biomass gasifier was selected for this model development because the syngas produced by it is better suited for Fischer-Tropsch synthesis with an iron-based catalyst for which a large amount of experimental data are available. Bechtel with Amoco as a subcontractor developed a conceptual baseline design and several alternative designs for indirect coal liquefaction facilities. In addition, ASPEN Plus process flowsheet simulation models were developed for each of designs. These models were used to perform several parametric studies to investigate various alternatives for improving the economics of indirect coal liquefaction.

  1. Hydrologic conditions and distribution of selected radiochemical and chemical constituents in water, Snake River Plain aquifer, Idaho National Engineering Laboratory, Idaho, 1992 through 1995

    SciTech Connect

    Bartholomay, R.C.; Tucker, B.J.; Ackerman, D.J.; Liszewski, M.J.

    1997-04-01

    Radiochemical and chemical wastewater discharged since 1952 to infiltration ponds and disposal wells at the Idaho National Engineering Laboratory (INEL) has affected water quality in the Snake River Plain aquifer. The US Geological Survey, in cooperation with the US Department of Energy, maintains a monitoring network at the INEL to determine hydrologic trends and to delineate the movement of radiochemical and chemical wastes in the aquifer. This report presents an analysis of water-level and water-quality data collected from the Snake River Plain aquifer during 1992--95.

  2. Methodology for evaluating lateral boundary conditions in the regional chemical transport model MATCH (v5.5.0) using combined satellite and ground-based observations

    NASA Astrophysics Data System (ADS)

    Andersson, E.; Kahnert, M.; Devasthale, A.

    2015-11-01

    Hemispheric transport of air pollutants can have a significant impact on regional air quality, as well as on the effect of air pollutants on regional climate. An accurate representation of hemispheric transport in regional chemical transport models (CTMs) depends on the specification of the lateral boundary conditions (LBCs). This study focuses on the methodology for evaluating LBCs of two moderately long-lived trace gases, carbon monoxide (CO) and ozone (O3), for the European model domain and over a 7-year period, 2006-2012. The method is based on combining the use of satellite observations at the lateral boundary with the use of both satellite and in situ ground observations within the model domain. The LBCs are generated by the global European Monitoring and Evaluation Programme Meteorological Synthesizing Centre - West (EMEP MSC-W) model; they are evaluated at the lateral boundaries by comparison with satellite observations of the Terra-MOPITT (Measurements Of Pollution In The Troposphere) sensor (CO) and the Aura-OMI (Ozone Monitoring Instrument) sensor (O3). The LBCs from the global model lie well within the satellite uncertainties for both CO and O3. The biases increase below 700 hPa for both species. However, the satellite retrievals below this height are strongly influenced by the a priori data; hence, they are less reliable than at, e.g. 500 hPa. CO is, on average, underestimated by the global model, while O3 tends to be overestimated during winter, and underestimated during summer. A regional CTM is run with (a) the validated monthly climatological LBCs from the global model; (b) dynamical LBCs from the global model; and (c) constant LBCs based on in situ ground observations near the domain boundary. The results are validated against independent satellite retrievals from the Aqua-AIRS (Atmospheric InfraRed Sounder) sensor at 500 hPa, and against in situ ground observations from the Global Atmospheric Watch (GAW) network. It is found that (i) the use of

  3. Effect of processing of rapeseed under defined conditions in a pilot plant on chemical composition and standardized ileal amino acid digestibility in rapeseed meal for pigs.

    PubMed

    Eklund, M; Sauer, N; Schöne, F; Messerschmidt, U; Rosenfelder, P; Htoo, J K; Mosenthin, R

    2015-06-01

    Five rapeseed meals (RSM) were produced from a single batch of rapeseed in a large-scale pilot plant under standardized conditions. The objective was to evaluate the effect of residence time in the desolventizer/toaster (DT) on chemical composition and standardized ileal digestibility (SID) of AA in RSM. Four RSM, with 48, 64, 76, and 93 min residence time and using unsaturated steam in the DT, referred to as RSM48, RSM64, RSM76, and RSM93, respectively, and 1 low-glucosinolate RSM, which was subjected to sequential treatment with unsaturated steam, saturated steam, and dry heat in the DT, referred to as low-GSL RSM, were assayed. Six barrows (average initial BW = 22 ± 1 kg) were surgically fitted with a T-cannula at the distal ileum. Pigs were allotted to a 5 × 6 row × column design with 5 diets and 5 periods. The 5 RSM were included in a cornstarch-casein-based basal diet. In addition, basal ileal endogenous losses and SID of AA originating from casein were determined at the conclusion of the experiment in 2 additional periods by means of the regression method and using 3 graded levels of casein. The SID of AA in the 5 RSM was determined in difference to SID of AA originating from casein. The glucosinolates (GSL) were efficiently reduced, whereas NDF, ADF, ADL, and NDIN contents increased and reactive Lys (rLys) and Lys:CP ratio decreased as the residence time in the DT was increased from 48 to 93 min. The SID of most AA in RSM linearly decreased (P < 0.05) as the residence time in the DT increased from 48 to 93 min. Moreover, there was a linear decrease (P < 0.05) in SID of AA with increasing NDF, ADF, ADL, and NDIN contents in these RSM, whereas SID of AA linearly decreased (P < 0.05) with decreasing levels of GSL and rLys and a decreasing Lys:CP ratio. The decrease (P < 0.05) in SID of AA amounted from 3 up to 6 (percentage units) for most AA, except for SID of Cys and Lys, which decreased by 10 and 11%-units (P < 0.05), respectively, as the residence time

  4. SLUDGE WASHING AND DEMONSTRATION OF THE DWPF FLOWSHEET IN THE SRNL SHIELDED CELLS FOR SLUDGE BATCH 6 QUALIFICATION

    SciTech Connect

    Pareizs, J.; Pickenheim, B.; Bannochie, C.; Billings, A.; Bibler, N.; Click, D.

    2010-10-01

    Prior to initiating a new sludge batch in the Defense Waste Processing Facility (DWPF), Savannah River National Laboratory (SRNL) is required to simulate this processing, including Chemical Process Cell (CPC) simulation, waste glass fabrication, and chemical durability testing. This report documents this simulation for the next sludge batch, Sludge Batch 6 (SB6). SB6 consists of Tank 12 material that has been transferred to Tank 51 and subjected to Low Temperature Aluminum Dissolution (LTAD), Tank 4 sludge, and H-Canyon Pu solutions. Following LTAD and the Tank 4 addition, Liquid Waste Operations (LWO) provided SRNL a 3 L sample of Tank 51 sludge for SB6 qualification. Pu solution from H Canyon was also received. SB6 qualification included washing the sample per LWO plans/projections (including the addition of Pu from H Canyon), DWPF CPC simulations, waste glass fabrication (vitrification), and waste glass characterization and chemical durability evaluation. The following are significant observations from this demonstration. Sludge settling improved slightly as the sludge was washed. SRNL recommended (and the Tank Farm implemented) one less wash based on evaluations of Tank 40 heel projections and projections of the glass composition following transfer of Tank 51 to Tank 40. Thorium was detected in significant quantities (>0.1 wt % of total solids) in the sludge. In past sludge batches, thorium has been determined by Inductively Coupled Plasma-Mass Spectroscopy (ICP-MS), seen in small quantities, and reported with the radionuclides. As a result of the high thorium, SRNL-AD has added thorium to their suite of Inductively Coupled Plasma-Atomic Emission Spectroscopy (ICP-AES) elements. The acid stoichiometry for the DWPF Sludge Receipt and Adjustment Tank (SRAT) processing of 115%, or 1.3 mol acid per liter of SRAT receipt slurry, was adequate to accomplish some of the goals of SRAT processing: nitrite was destroyed to below 1,000 mg/kg and mercury was removed to

  5. SLUDGE WASHING AND DEMONSTRATION OF THE DWPF FLOWSHEET IN THE SRNL SHIELDED CELLS FOR SLUDGE BATCH 5 QUALIFICATION

    SciTech Connect

    Pareizs, J; Cj Bannochie, C; Damon Click, D; Dan Lambert, D; Michael Stone, M; Bradley Pickenheim, B; Amanda Billings, A; Ned Bibler, N

    2008-11-10

    Sludge Batch 5 (SB5) is predominantly a combination of H-modified (HM) sludge from Tank 11 that underwent aluminum dissolution in late 2007 to reduce the total mass of sludge solids and aluminum being fed to the Defense Waste Processing Facility (DWPF) and Purex sludge transferred from Tank 7. Following aluminum dissolution, the addition of Tank 7 sludge and excess Pu to Tank 51, Liquid Waste Operations (LWO) provided the Savannah River National Laboratory (SRNL) a 3-L sample of Tank 51 sludge for SB5 qualification. SB5 qualification included washing the sample per LWO plans/projections (including the addition of a Pu/Be stream from H Canyon), DWPF Chemical Process Cell (CPC) simulations, waste glass fabrication (vitrification), and waste glass chemical durability evaluation. This report documents: (1) The washing (addition of water to dilute the sludge supernatant) and concentration (decanting of supernatant) of the Tank 51 qualification sample to adjust sodium content and weight percent insoluble solids to Tank Farm projections. (2) The performance of a DWPF CPC simulation using the washed Tank 51 sample. This includes a Sludge Receipt and Adjustment Tank (SRAT) cycle, where acid is added to the sludge to destroy nitrite and remove mercury, and a Slurry Mix Evaporator (SME) cycle, where glass frit is added to the sludge in preparation for vitrification. The SME cycle also included replication of five canister decontamination additions and concentrations. Processing parameters for the CPC processing were based on work with a non radioactive simulant. (3) Vitrification of a portion of the SME product and Product Consistency Test (PCT) evaluation of the resulting glass. (4) Rheology measurements of the initial slurry samples and samples after each phase of CPC processing. This work is controlled by a Task Technical and Quality Assurance Plan (TTQAP) , and analyses are guided by an Analytical Study Plan. This work is Technical Baseline Research and Development (R

  6. Computational non-chemically equilibrium model on the current zero simulation in a model N2 circuit breaker under the free recovery condition

    NASA Astrophysics Data System (ADS)

    Sun, Hao; Tanaka, Yasunori; Tomita, Kentaro; Wu, Yi; Rong, Mingzhe; Uesugi, Yoshihiko; Ishijima, Tatsuo

    2016-02-01

    A non-chemically equilibrium (non-CE) model was established to investigate the N2 arc plasma in the decaying phase during the arc interruption, and was validated by comparison with the experimental results based on laser Thomson scattering. Unlike the conventional model assuming the local thermodynamic equilibrium (LTE), in this non-CE model, the magneto-hydro-dynamics (MHD) method was coupled with the reaction kinetics to obtain the time-dependent species compositions and properties. The current calculation took into account five species in hot gas and 22 chemical reactions in total. The time-dependent species compositions of hot N2 were derived from the mass conservation equation for each species, considering the effect of the convection, diffusion and the chemical reaction. The influence of the non-CE compositions on the arc decaying behavior was realized by updating the thermodynamic and transport properties at each iterative step. The results indicate that the non-CE model can result in the departure of the arc decaying behavior from the LTE model, because it alters the time evolution of the species composition and consequently changes the thermodynamic and transport properties. At the edge of the arc, the time evolutions of the species are dominant by both the diffusion and the chemical reactions while at the center of the arc they are mainly influenced by the chemical reactions. Generally, the non-CE effect can lead to the delay of all the particles’ variations, particularly the electron decay, so that the arc interruption performance will be reduced compared with that in the LTE model.

  7. Hydrologic conditions and distribution of selected radiochemical and chemical constituents in water, Snake River Plain aquifer, Idaho National Engineering Laboratory, Idaho, 1989 through 1991

    SciTech Connect

    Bartholomay, R.C.; Orr, B.R.; Liszewski, M.J.; Jensen, R.G.

    1995-08-01

    Radiochemical and chemical wastewater discharged since 1952 to infiltration ponds and disposal wells at the Idaho National Engineering Laboratory (INEL) has affected water quality in the Snake River Plain aquifer. The U.S. Geological Survey, in cooperation with the U.S. Department of Energy, maintains a continuous monitoring network at the INEL to determine hydrologic trends and to delineate the movement of radiochemical and chemical wastes in the aquifer. This report presents an analysis of water-level and water-quality data collected from the Snake River Plain aquifer during 1989-91. Water in the eastern Snake River Plain aquifer moves principally through fractures and interflow zones in basalt, generally flows southwestward, and eventually discharges at springs along the Snake River. The aquifer is recharged principally from irrigation water, infiltration of streamflow, and ground-water inflow from adjoining mountain drainage basins. Water levels in wells throughout the INEL generally declined during 1989-91 due to drought. Detectable concentrations of radiochemical constituents in water samples from wells in the Snake River Plain aquifer at the INEL decreased or remained constant during 1989-91. Decreased concentrations are attributed to reduced rates of radioactive-waste disposal, sorption processes, radioactive decay, and changes in waste-disposal practices. Detectable concentrations of chemical constituents in water from the Snake River Plain aquifer at the INEL were variable during 1989-91. Sodium and chloride concentrations in the southern part of the INEL increased slightly during 1989-91 because of increased waste-disposal rates and a lack of recharge from the Big Lost River. Plumes of 1,1,1-trichloroethane have developed near the Idaho Chemical Processing Plant and the Radioactive Waste Management Complex as a result of waste disposal practices.

  8. WASHING AND DEMONSTRATION OF THE DWPF FLOWSHEET IN THE SRNL SHIELDED CELLS USING POST ALUMINUM DISSOLUTION TANK 51 SLUDGE SLURRY

    SciTech Connect

    Pareizs, J; Cj Bannochie, C; Damon Click, D; Erich Hansen, E; Dan Lambert, D; Michael Stone, M

    2008-04-28

    The remaining contents of Tank 51 from Sludge Batch 4 will be blended with Purex sludge from Tank 7 to constitute Sludge Batch 5 (SB5). The Savannah River Site (SRS) Liquid Waste Organization (LWO) has completed caustic addition to Tank 51 to perform low temperature Al dissolution on the H-Modified (HM) sludge material to reduce the total mass of sludge solids and Al being fed to the Defense Waste Processing Facility (DWPF). The Savannah River National Lab (SRNL) has also completed aluminum dissolution tests using a 3-L sample of Tank 51 sludge slurry through funding by DOE EM-21. This report documents assessment of downstream impacts of the aluminum dissolved sludge, which were investigated so technical issues could be identified before the start of SB5 processing. This assessment included washing the aluminum dissolved sludge to a Tank Farm projected sodium concentration and weight percent insoluble solids content and DWPF Chemical Process Cell (CPC) processing using the washed sludge. Based on the limited testing, the impact of aluminum dissolution on sludge settling is not clear. Settling was not predictable for the 3-L sample. Compared to the post aluminum dissolution sample, settling after the first wash was slower, but settling after the second wash was faster. For example, post aluminum dissolution sludge took six days to settle to 60% of the original sludge slurry height, while Wash 1 took nearly eight days, and Wash 2 only took two days. Aluminum dissolution did impact sludge rheology. A comparison between the as-received, post aluminum dissolution and washed samples indicate that the downstream materials were more viscous and the concentration of insoluble solids less than that of the starting material. This increase in viscosity may impact Tank 51 transfers to Tank 40. The impact of aluminum dissolution on DWPF CPC processing cannot be determined because acid addition for the Sludge Receipt and Adjustment Tank (SRAT) cycle was under-calculated and thus

  9. DEMONSTRATION OF THE DWPF FLOWSHEET IN THE SRNL SHIELDED CELLS WITH TANK 40 AND H CANYON NEPTUNIUM

    SciTech Connect

    Pareizs, J; Bradley Pickenheim, B; Cj Bannochie, C; Michael Stone, M

    2009-04-28

    The Defense Waste Processing Facility (DWPF) is currently processing Sludge Batch 5 (SB5) from Tank 40. SB5 contains the contents of Tank 51 from November 2008, qualified by the Savannah River National Laboratory (SRNL) and the heel in Tank 40 remaining from Sludge Batch 4. Current Liquid Waste Operations (LWO) plans are to (1) decant supernatant from Tank 40 to remove excess liquid caused by a leaking slurry pump and (2) receive a Np stream from H Canyon It should be noted that the Np stream contains significant nitrate requiring addition of nitrite to Tank 40 to maintain a high nitrite to nitrate ratio for corrosion control. SRNL has been requested to qualify the proposed changes; determine the impact on DWPF processability in terms of hydrogen generation, rheology, etc.; evaluate antifoam addition strategy; and evaluate mercury stripping. Therefore, SRNL received a 3 L sample of Tank 40 following the transfer of Tank 51 to Tank 40 (Tank Farm Sample HTF-40-08-157 to be used in testing and to perform the required Waste Acceptance Product Specifications radionuclide analyses). Based on Tank Farm projections, SRNL decanted a portion* of the sample, added sodium nitrite, and added a Np solution from H Canyon representative of the Np to be dispositioned to Tank 40 (neutralized to 0.6 M excess hydroxide). The resulting material was used in a DWPF Chemical Process Cell (CPC) demonstration -- a Sludge Receipt and Adjustment Tank (SRAT) cycle and a Slurry Mix Evaporator (SME) cycle. Preliminary data from the demonstration has been reported previously. This report includes discussion of these results and additional results, including comparisons to Tank Farm projections and the SB5 demonstration.

  10. Effect of Precipitation Conditions on the Specific Surface Area of Neptunium Oxide

    SciTech Connect

    HILL, BENJAMINC.

    2004-06-01

    Neptunium oxalate was precipitated under nominal and bounding HB-Line flowsheet conditions. The nominal case represents expected normal HB-Line operation. The bounding case represents process flowsheet extremes that could occur which are anticipated to decrease particle size and increase surface area. The neptunium oxalate produced under bounding conditions was used to validate the effectiveness of HB-Line calcination conditions. The maximum specific surface area of the neptunium oxide (NpO2) used in gas generation testing was 5.34 m2/g. Experiments were conducted to verify that even under bounding precipitation conditions the SSA of NpO2 produced would remain within the range evaluated during gas generation testing. The neptunium oxalate from nominal and bounding precipitation conditions was calcined at 600 degrees Celsius and 625 degrees Celsius, respectively, to form NpO2. Samples from each batch of neptunium oxalate were calcined for one, two, or four hours. Results indicate that the SSA of NpO2 continues to decrease between one and four hours. After two hours of calcination at 625 degrees Celsius, the SSA of NpO2 from the bounding case meets the surface area requirements for limiting moisture uptake.

  11. Effects of Growth Conditions on Structural Properties of ZnO Nanostructures on Sapphire Substrate by Metal–Organic Chemical Vapor Deposition

    PubMed Central

    2009-01-01

    ZnO was grown on sapphire substrate by metal–organic chemical vapor deposition using the diethylzinc (DEZn) and oxygen (O2) as source chemicals at 500 °C. Influences of the chamber pressure and O2/DEZn ratio on the ZnO structural properties were discussed. It was found that the chamber pressure has significant effects on the morphology of ZnO and could result in various structures of ZnO including pyramid-like, worm-like, and columnar grain. When the chamber pressure was kept at 10 Torr, the lowest full width at half-maximum of ZnO (002) of 175 arc second can be obtained. On the other hand, by lowering the DEZn flow rate, the crystal quality of ZnO can be improved. Under high DEZn flow rate, the ZnO nanowall-network structures were found to grow vertically on the sapphire substrate without using any metal catalysts. It suggests that higher DEZn flow rate promotes three-dimensional growth mode resulting in increased surface roughness. Therefore, some tip on the ZnO surface could act as nucleation site. In this work, the growth process of our ZnO nanowall networks is said to follow the self-catalyzed growth mechanism under high-DEZn flow rate. PMID:20596413

  12. Chemical Disposition of Plutonium in Hanford Site Tank Wastes

    SciTech Connect

    Delegard, Calvin H.; Jones, Susan A.

    2015-05-07

    This report examines the chemical disposition of plutonium (Pu) in Hanford Site tank wastes, by itself and in its observed and potential interactions with the neutron absorbers aluminum (Al), cadmium (Cd), chromium (Cr), iron (Fe), manganese (Mn), nickel (Ni), and sodium (Na). Consideration also is given to the interactions of plutonium with uranium (U). No consideration of the disposition of uranium itself as an element with fissile isotopes is considered except tangentially with respect to its interaction as an absorber for plutonium. The report begins with a brief review of Hanford Site plutonium processes, examining the various means used to recover plutonium from irradiated fuel and from scrap, and also examines the intermediate processing of plutonium to prepare useful chemical forms. The paper provides an overview of Hanford tank defined-waste–type compositions and some calculations of the ratios of plutonium to absorber elements in these waste types and in individual waste analyses. These assessments are based on Hanford tank waste inventory data derived from separately published, expert assessments of tank disposal records, process flowsheets, and chemical/radiochemical analyses. This work also investigates the distribution and expected speciation of plutonium in tank waste solution and solid phases. For the solid phases, both pure plutonium compounds and plutonium interactions with absorber elements are considered. These assessments of plutonium chemistry are based largely on analyses of idealized or simulated tank waste or strongly alkaline systems. The very limited information available on plutonium behavior, disposition, and speciation in genuine tank waste also is discussed. The assessments show that plutonium coprecipitates strongly with chromium, iron, manganese and uranium absorbers. Plutonium’s chemical interactions with aluminum, nickel, and sodium are minimal to non-existent. Credit for neutronic interaction of plutonium with these absorbers

  13. SLUDGE WASHING AND DEMONSTRATION OF THE DWPF FLOWSHEET IN THE SRNL SHIELDED CELLS FOR SLUDGE BATCH 7A QUALIFICATION

    SciTech Connect

    Pareizs, J.; Billings, A.; Click, D.

    2011-07-08

    Waste Solidification Engineering (WSE) has requested that characterization and a radioactive demonstration of the next batch of sludge slurry (Sludge Batch 7a*) be completed in the Shielded Cells Facility of the Savannah River National Laboratory (SRNL) via a Technical Task Request (TTR). This characterization and demonstration, or sludge batch qualification process, is required prior to transfer of the sludge from Tank 51 to the Defense Waste Processing Facility (DWPF) feed tank (Tank 40). The current WSE practice is to prepare sludge batches in Tank 51 by transferring sludge from other tanks. Discharges of nuclear materials from H Canyon are often added to Tank 51 during sludge batch preparation. The sludge is washed and transferred to Tank 40, the current DWPF feed tank. Prior to transfer of Tank 51 to Tank 40, SRNL simulates the Tank Farm and DWPF processes with a Tank 51 sample (referred to as the qualification sample). Sludge Batch 7a (SB7a) is composed of portions of Tanks 4, 7, and 12; the Sludge Batch 6 heel in Tank 51; and a plutonium stream from H Canyon. SRNL received the Tank 51 qualification sample (sample ID HTF-51-10-125) following sludge additions to Tank 51. This report documents: (1) The washing (addition of water to dilute the sludge supernate) and concentration (decanting of supernate) of the SB7a - Tank 51 qualification sample to adjust sodium content and weight percent insoluble solids to Tank Farm projections. (2) The performance of a DWPF Chemical Process Cell (CPC) simulation using the washed Tank 51 sample. The simulation included a Sludge Receipt and Adjustment Tank (SRAT) cycle, where acid was added to the sludge to destroy nitrite and reduce mercury, and a Slurry Mix Evaporator (SME) cycle, where glass frit was added to the sludge in preparation for vitrification. The SME cycle also included replication of five canister decontamination additions and concentrations. Processing parameters were based on work with a non

  14. Evaluation of interim and final waste forms for the newly generated liquid low-level waste flowsheet

    SciTech Connect

    Abotsi, G.M.K.; Bostick, D.T.; Beck, D.E.

    1996-05-01

    The purpose of this review is to evaluate the final forms that have been proposed for radioactive-containing solid wastes and to determine their application to the solid wastes that will result from the treatment of newly generated liquid low-level waste (NGLLLW) and Melton Valley Storage Tank (MVST) supernate at the Oak Ridge National Laboratory (ORNL). Since cesium and strontium are the predominant radionuclides in NGLLLW and MVST supernate, this review is focused on the stabilization and solidification of solid wastes containing these radionuclides in cement, glass, and polymeric materials-the principal waste forms that have been tested with these types of wastes. Several studies have shown that both cesium and strontium are leached by distilled water from solidified cement, although the leachabilities of cesium are generally higher than those of strontium under similar conditions. The situation is exacerbated by the presence of sulfates in the solution, as manifested by cracking of the grout. Additives such as bentonite, blast-furnace slag, fly ash, montmorillonite, pottery clay, silica, and zeolites generally decrease the cesium and strontium release rates. Longer cement curing times (>28 d) and high ionic strengths of the leachates, such as those that occur in seawater, also decrease the leach rates of these radionuclides. Lower cesium leach rates are observed from vitrified wastes than from grout waste forms. However, significant quantities of cesium are volatilized due to the elevated temperatures required to vitrify the waste. Hence, vitrification will generally require the use of cleanup systems for the off-gases to prevent their release into the atmosphere.

  15. Evaluating Crude Oil Chemical Dispersion Efficacy In A Flow-Through Wave Tank Under Regular Non-Breaking Wave And Breaking Wave Conditions

    EPA Science Inventory

    Testing dispersant effectiveness under conditions similar to that of the open environment is required for improvements in operational procedures and the formulation of regulatory guidelines. To this end, a novel wave tank facility was fabricated to study the dispersion of crude ...

  16. Development Of Ion Chromatography Methods To Support Testing Of The Glycolic Acid Reductant Flowsheet In The Defense Waste Processing Facility

    SciTech Connect

    Wiedenman, B. J.; White, T. L.; Mahannah, R. N.; Best, D. R.; Stone, M. E.; Click, D. R.; Lambert, D. P.; Coleman, C. J.

    2013-10-01

    Ion Chromatography (IC) is the principal analytical method used to support studies of Sludge Reciept and Adjustment Tank (SRAT) chemistry at DWPF. A series of prior analytical ''Round Robin'' (RR) studies included both supernate and sludge samples from SRAT simulant, previously reported as memos, are tabulated in this report.2,3 From these studies it was determined to standardize IC column size to 4 mm diameter, eliminating the capillary column from use. As a follow on test, the DWPF laboratory, the PSAL laboratory, and the AD laboratory participated in the current analytical RR to determine a suite of anions in SRAT simulant by IC, results also are tabulated in this report. The particular goal was to confirm the laboratories ability to measure and quantitate glycolate ion. The target was + or - 20% inter-lab agreement of the analyte averages for the RR. Each of the three laboratories analyzed a batch of 12 samples. For each laboratory, the percent relative standard deviation (%RSD) of the averages on nitrate, glycolate, and oxalate, was 10% or less. The three laboratories all met the goal of 20% relative agreement for nitrate and glycolate. For oxalate, the PSAL laboratory reported an average value that was 20% higher than the average values reported by the DWPF laboratory and the AD laboratory. Because of this wider window of agreement, it was concluded to continue the practice of an additional acid digestion for total oxalate measurement. It should also be noted that large amounts of glycolate in the SRAT samples will have an impact on detection limits of near eluting peaks, namely Fluoride and Formate. A suite of scoping experiments are presented in the report to identify and isolate other potential interlaboratory disceprancies. Specific ion chromatography inter-laboratory method conditions and differences are tabulated. Most differences were minor but there are some temperature control equipment differences that are significant leading to a recommendation of

  17. Groupings of organic waste chemicals based on sorption, biotransformation and hydrolysis at standard conditions for application to the deep subsurface environment

    SciTech Connect

    Phillips, S.L.; Hale, F.V.; Tsang, C.F.

    1988-01-01

    Chemical and biological reactions of organic hazardous wastes disposed to injection wells at depths down to 7000 feet deep are assessed. At these depths, the major reactions involving organic wastes include hydrolysis, biotransformation and sorption. However, experimental data on reactions of organics in the deep subsurface are sparse or nonexistent. Tables are given on values for hydrolysis, sorption and biotransformation reactions obtained from research publications, mostly at 25/degree/C and atmospheric pressure. It is suggested that the more plentiful data on reactions at the land surface be used to approximate the rates of hydrolysis and biotransformation and sorption equilibrium by taking into account the expected subsurface environment. For example, predictive methods will take into consideration a deep subsurface environment which has: a higher temperature and pressure than the land surface; fewer kinds of microorganisms and a substantially lower concentration of microorganisms; lower organic carbon levels; and, highly saline ground waters. 58 refs., 1 figs., 12 tabs.

  18. Investigation of the chemical stability of the laser-induced fluorescence tracers acetone, diethylketone, and toluene under IC engine conditions using Raman spectroscopy.

    PubMed

    Trost, Johannes; Zigan, Lars; Eichmann, Simone C; Seeger, Thomas; Leipertz, Alfred

    2013-09-01

    This paper reports on an investigation of the chemical stability of the common laser-induced fluorescence (LIF) tracers acetone, diethylketone, and toluene. Stability is analyzed using linear Raman spectroscopy inside a heated pressure cell with optical access, which is used for the LIF calibration of these tracers. The measurements examine the influence of temperature, pressure, and residence time on tracer oxidation, which occurs without a rise in temperature or pressure inside the cell, highlighting the need for optical detection. A comparison between the three different tracers shows large differences, with diethylketone having the lowest and toluene by far the highest stability. An analysis of the sensitivity of the measurement shows that the detection limit of the oxidized tracer is well below 3% molar fraction, which is typical for LIF applications in combustion devices such as internal combustion (IC) engines. Furthermore, the effect on the LIF signal intensity is examined in an isothermal turbulent mixing study. PMID:24085091

  19. Radiation and chemical crosslinking promote strain hardening behavior and molecular alignment in ultra high molecular weight polyethylene during multi-axial loading conditions.

    PubMed

    Kurtz, S M; Pruitt, L A; Jewett, C W; Foulds, J R; Edidin, A A

    1999-08-01

    The mechanical behavior and evolution of crystalline morphology during large deformation of eight types of virgin and crosslinked ultra high molecular weight polyethylene (UHMWPE) were studied using the small punch test and transmission electron microscopy (TEM). We investigated the hypothesis that both radiation and chemical crosslinking hinder molecular mobility at large deformations, and hence promote strain hardening and molecular alignment during the multiaxial loading of the small punch test. Chemical crosslinking of UHMWPE was performed using 0.25% dicumyl peroxide (GHR 8110, GUR 1020 and 1050), and radiation crosslinking was performed using 150 kGy of electron beam radiation (GUR 1150). Crosslinking increased the ultimate load at failure and decreased the ultimate displacement of the polyethylenes during the small punch test. Crosslinking also increased the near-ultimate hardening behavior of the polyethylenes. Transmission electron microscopy was used to characterize the crystalline morphology of the bulk material, undeformed regions of the small punch test specimens, and deformed regions of the specimens oriented perpendicular and parallel to the punch direction. In contrast with the virgin polyethylenes, which showed only subtle evidence of lamellar alignment, the crosslinked polyethylenes exhibited enhanced crystalline lamellae orientation after the small punch test, predominantly in the direction parallel to the punch direction or deformation axis. Thus, the results of this study support the hypothesis that crosslinking promotes strain hardening during multiaxial loading because of increased resistance to molecular mobility at large deformations effected by molecular alignment. The data also illustrate the sensitivity of large deformation mechanical behavior and crystalline morphology to the method of crosslinking and resin of polyethylene. PMID:10458558

  20. Heat-affected zone fracture toughness of 420-500 MPa yield strength steels: Effects of chemical composition and welding conditions

    SciTech Connect

    Tronskar, J.P. )

    1993-02-01

    During the last five years, high-strength steels with yield strengths in the range 420 to 500 MPa have attracted considerable interest within the offshore industry, primarily due to the potential for weight saving and reduction in volume of weld metal through the use of reduced section thicknesses. With respect to chemical composition these steels are developed following much the same philosophy as for the modern normalized structural steels. Due to the increased stress level in these higher strength steels, it is anticipated that brittle fracture initiation occurring in the coarse-gained HAZ will be more critical for these steels than for the lower strength normalized grades. The objective of this paper is to present the results from several experimental investigations carried out at VERITEC during the last five years to study the factors affecting the crack tip opening displacement (CTOD) fracture toughness of the heat-affected zone (HAZ) in structural steels in the yield strength range 420-500 MPa. Typical CTOD fracture toughnesses of the HAZ in normalized 350-MPa yield strength steels used in offshore structures are also presented for comparison. The results of the investigations confirm that the same chemical compositional factors which are known to influence the HAZ fracture toughness of normalized steels are also important for the 420-500-MPa yield strength steels. It is demonstrated that the width of the HAZ is important for the initiation of brittle fracture of pop-in and that this width must exceed a certain minimum value for such events to occur.

  1. α-pinene photooxidation under controlled chemical conditions - Part 1: Gas-phase composition in low- and high-NOx environments

    NASA Astrophysics Data System (ADS)

    Eddingsaas, N. C.; Loza, C. L.; Yee, L. D.; Seinfeld, J. H.; Wennberg, P. O.

    2012-07-01

    The OH oxidation of α-pinene under both low- and high-NOx environments was studied in the Caltech atmospheric chambers. Ozone was kept low to ensure OH was the oxidant. The initial α-pinene concentration was 20-50 ppb to ensure that the dominant peroxy radical pathway under low-NOx conditions is reaction with HO2, produced from reaction of OH with H2O2, and under high-NOx conditions, reactions with NO. Here we present the gas-phase results observed. Under low-NOx conditions the main first generation oxidation products are a number of α-pinene hydroxy hydroperoxides and pinonaldehyde, accounting for over 40% of the yield. In all, 65-75% of the carbon can be accounted for in the gas phase; this excludes first-generation products that enter the particle phase. We suggest that pinonaldehyde forms from RO2 + HO2 through an alkoxy radical channel that regenerates OH, a mechanism typically associated with acyl peroxy radicals, not alkyl peroxy radicals. The OH oxidation and photolysis of α-pinene hydroxy hydroperoxides leads to further production of pinonaldehyde, resulting in total pinonaldehyde yield from low-NOx OH oxidation of ~33%. The low-NOx OH oxidation of pinonaldehyde produces a number of carboxylic acids and peroxyacids known to be important secondary organic aerosol components. Under high-NOx conditions, pinonaldehyde was also found to be the major first-generation OH oxidation product. The high-NOx OH oxidation of pinonaldehyde did not produce carboxylic acids and peroxyacids. A number of organonitrates and peroxyacyl nitrates are observed and identified from α-pinene and pinonaldehyde.

  2. Effect of condensation agents and minerals for oligopeptide formation under mild and hydrothermal conditions in related to chemical evolution of proteins

    NASA Astrophysics Data System (ADS)

    Kawamura, Kunio; Takeya, Hitoshi; Kushibe, Takao

    2009-07-01

    The role of condensation agents and minerals for oligopeptide formation was inspected to see whether minerals possess catalytic activity under mild and hydrothermal conditions. Under mild conditions, oligopeptide formation from negatively charged amino acids (Asp and Glu) using different minerals and the elongation of alanine oligopeptides ((Ala) 2-(Ala) 5) were attempted using apatite minerals. Oligo(Asp) up to 10 amino acid units from Asp were observed in the presence of 1-ethyl-3-(3-dimethylaminopropyl carbodiimide (EDC). Notable influence of minerals was not detected for the oligo(Asp) formation. Oligo(Asp) was gradually degraded by the further incubation in the presence of EDC in both the absence and presence of minerals. The formation of oligo(Glu) was less efficient in the presence of carbonyldiimidazole. The elongation from (Ala) 3, (Ala) 4, and (Ala) 5 and the formation of diketopiperazine from (Ala) 2 proceeded immediately in the presence of EDC in the meantime of the sample preparations. In addition, it was unexpected that the disappearance of the products and the reformation of the reactants occurred by the further incubation for 24 h; for instance, (Ala) 5 decreased but (Ala) 4 increased with increasing the reaction time in the reaction of (Ala) 4 with EDC. These facts suggest that the activation of the reactant amino acids or peptides immediately occurs. Under the simulated hydrothermal conditions, EDC did not enhance the formation of oligopeptides from Asp, Glu or Ala nor the spontaneous formation of (Ala) 5 from (Ala) 4.

  3. A new cascade-less engine operated from subsonic to hypersonic conditions: designed by computational fluid dynamics of compressible turbulence with chemical reactions

    NASA Astrophysics Data System (ADS)

    Naitoh, Ken; Nakamura, Kazushi; Emoto, Takehiro

    2010-12-01

    By using our computational fluid dynamic models, a new type of single engine capable of operating over a wide range of Mach numbers from subsonic to hypersonic regimes is proposed for airplanes, whereas traditional piston engines, turbojet engines, and scram engines work only under a narrower range of operating conditions. The new engine has no compressors or turbines such as those used in conventional turbojet engines. An important point is its system of super multijets that collide to compress gas for the transonic regime. Computational fluid dynamics is applied to clarify the potential of this engine. The peak pressure at the combustion center is over 2.5 MPa, while that just before ignition is over 1.0 MPa. The maximum power of this engine will be sufficient for actual use. Under the conditions of higher Mach numbers, the main intake passage located in front of the super multijet nozzles, takes in air more. That results in a ram or scramjet engine for supersonic and hypersonic conditions.

  4. Influence of temporal variations and climatic conditions on the physical and chemical characteristics of dew and rain in South-West Morocco

    NASA Astrophysics Data System (ADS)

    Lekouch, I.; Kabbachi, B.; Milimouk-Melnytchouk, I.; Muselli, M.; Beysens, D.

    2010-07-01

    In order to be used as alternative or supplemental sources of water, the physical and physico-chemical characteristics of rain, fog and dew water were investigated at Mirleft in the arid coastal environment of south-west Morocco. A site was instrumented on a terrace with a fog net collector, four 1 m2 inclined (30° ) test dew condenser, together with a weather station providing standard meteorological data. The study was carried out between May 1, 2007 and Avril 30, 2008. Over the one year period were noted 178 dew events (49% yearly occurrence), 31 rain events (8.5 % yearly occurrence) and 7 significant fog events (2 % yearly occurrence). The total quantity of collected water was 48.7 mm (rain), 18.9 mm (dew) and 1.4 mm (fog). Then collecting dew increases almost 40% the water yield although fog contributes to only 3%. A number of physico-chemical and biological parameters were also measured for dew and rain water: pH, electrical conductivity (EC), major anions (HCO3-,Cl-, SO42-,NO3-), major cations (NH4+, Na+, K+, Ca2+, Mg2+). It is found that the mean dew and rain pH are equal to 7.4 and 6.9, respectively and the mean EC are 730 ? S/cm and 316 ? S/cm, respectively, corresponding to large total mineralization. The ratio TA/TC < 1 indicates the alkaline nature of dew and rain water. The analysis of the major ions shows that the concentration of Cl- and Na+ is high compared to that of the other elements. To consider the marine and nonmarine origin of these ions, the fraction of salt coming from sea (SSF) was also calculated. While in dew Cl-, Na+ et Mg2+ are clearly of marine origine, the small SSF value for Ca2+, K+, SO4- et NO3- in dew suggests a considerable contribution of nonmarine origin for these components. In contrast, in rainwater, the values of the No Sea Salt Fraction (NSSF) indicates that only Ca2+ et NO3-are of non marine origin. The dry and transition seasons (spring, summer, fall) correspond to a water more concentrated in elements than during the

  5. Influence of ball milling and annealing conditions on the properties of L10 FePt nanoparticles fabricated by a new green chemical synthesis method

    NASA Astrophysics Data System (ADS)

    Hu, X. C.; Capobianchi, A.; Gallagher, R.; Hadjipanayis, G. C.

    2014-05-01

    In this work, a new green chemical strategy for the synthesis of L10 FePt alloy nanoparticles is reported. The precursor is a polycrystalline molecular complex (Fe(H2O)6PtCl6), in which Fe and Pt atoms are arranged on alternating planes and milled with NaCl to form nanocrystals. Then the mixture was annealed under reducing atmosphere (5% H2 and 95% Ar) at temperatures varying from 350 °C to 500 °C for 2 h with a heating rate of 5 °C/min. After the reduction, the mixture was washed with water to remove the NaCl and L10 FePt nanoparticles were obtained. The X-Ray Diffraction pattern showed the presence of the characteristic peaks of the fct phase of FePt nanoparticles. Influence of precursor/NaCl ratio and ball milling time on particle size was investigated. Transmission electron microscopy images revealed that smaller precursor/NaCl ratio (10 mg/20 g) and longer milling time (15 h) lead to smaller particle size and narrower size distribution. Milling time does not influence the coercivity much but the decrease of the amount of precursor leads to a decrease of coercivity from 10.8 kOe to 4.8 kOe.

  6. Si nanowires grown by Al-catalyzed plasma-enhanced chemical vapor deposition: synthesis conditions, electrical properties and application to lithium battery anodes

    NASA Astrophysics Data System (ADS)

    Toan, Le Duc; Moyen, Eric; Zamfir, Mihai Robert; Joe, Jemee; Kim, Young Woo; Pribat, Didier

    2016-01-01

    Silicon nanowires have been synhesized using Al as a catalyst. Silane (SiH4) diluted in H2 carrier gas was employed as Si precursor in a plasma enhanced chemical vapor deposition system operated at various temperatures (450 °C and 550 °C). Those growth temperatures, which are lower than the eutectic temperature in the Al-Si system (577 °C) suggests a vapor-solid-solid growth mechanism. Four point resistance measurements and back-gated current-voltage measurements indicated that silicon nanowires were heavily doped (p type), with a doping concentration of a few 1019 cm-3. We have measured hole mobility values of ˜16 cm2 V-1 s-1 at 450 °C and ˜30 cm2 V-1 s-1 at 550 °C. Transmission electron microscope analyses showed that the silicon nanowires were highly twinned even when they grow epitaxially on (111) Si substrates. We have also evaluated the use of those highly doped Si nanowires for lithium-ion battery anodes. We have observed a good cycling behavior during the first 65 charge-discharge cycles, followed by a slow capacity decay. After 150 cycles at a charge-discharge rate of 0.1 C, the electrode capacity was still 1400 mAh g-1. The ageing mechanism seems to be related to the delamination of the SiNWs from the stainless steel substrate on which they were grown.

  7. Influence of ball milling and annealing conditions on the properties of L1{sub 0} FePt nanoparticles fabricated by a new green chemical synthesis method

    SciTech Connect

    Hu, X. C.; Capobianchi, A.; Gallagher, R.; Hadjipanayis, G. C.

    2014-05-07

    In this work, a new green chemical strategy for the synthesis of L1{sub 0} FePt alloy nanoparticles is reported. The precursor is a polycrystalline molecular complex (Fe(H{sub 2}O){sub 6}PtCl{sub 6}), in which Fe and Pt atoms are arranged on alternating planes and milled with NaCl to form nanocrystals. Then the mixture was annealed under reducing atmosphere (5% H{sub 2} and 95% Ar) at temperatures varying from 350 °C to 500 °C for 2 h with a heating rate of 5 °C/min. After the reduction, the mixture was washed with water to remove the NaCl and L1{sub 0} FePt nanoparticles were obtained. The X-Ray Diffraction pattern showed the presence of the characteristic peaks of the fct phase of FePt nanoparticles. Influence of precursor/NaCl ratio and ball milling time on particle size was investigated. Transmission electron microscopy images revealed that smaller precursor/NaCl ratio (10 mg/20 g) and longer milling time (15 h) lead to smaller particle size and narrower size distribution. Milling time does not influence the coercivity much but the decrease of the amount of precursor leads to a decrease of coercivity from 10.8 kOe to 4.8 kOe.

  8. Novel chamber to measure equilibrium soil-air partitioning coefficients of low-volatility organic chemicals under conditions of varying temperature and soil moisture.

    PubMed

    Wolters, André; Linnemann, Volker; Smith, Kilian E C; Klingelmann, Eva; Park, Byung-Jun; Vereecken, Harry

    2008-07-01

    The need to determine soil-air partitioning coefficients (K(SA)) of low-volatility organic chemicals as a measure of their distribution in the soil surface after release into the environment resulted in the development of a novel chamber system, which has been filed for patent. A major advantage of this pseudo-static system is that sufficient time can be factored into the experiment to ensure that the system has achieved equilibrium. In a highly precise method, the air is collected in adsorption tubes and subsequently liberated in a thermodesorption system for the quantitation of the adsorbed compound. The precision of the method is great enough that even the effects of temperature and soil moisture on the soil-air partitioning of very low-volatility compounds can be quantified. Because of analytical detection limits, quantitation of these influences has not been possible to date. Functionality of the setup was illustrated by measurements on the fungicide fenpropimorph. K(SA) values of fenpropimorph displayed a negative relationship with temperature and soil moisture. The type of application (spraying or incorporation) and the use of formulated compounds was shown to have a major impact on the measured K(SA) values. Comparison with calculations using an estimation method revealed that the use of experimentally determined K(SA) values will facilitate a more adequate consideration of volatilization in recent model approaches. PMID:18678019

  9. Chemical Emergencies

    MedlinePlus

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

  10. Impact of environmental conditions on the chemical surface properties of Cu(In,Ga)(S,Se){sub 2} thin-film solar cell absorbers

    SciTech Connect

    Hauschild, D. E-mail: l.weinhardt@kit.edu; Meyer, F.; Pohlner, S.; Lechner, R.; Dietmüller, R.; Palm, J.; Heske, C.; Reinert, F.

    2014-05-14

    Environmentally driven aging effects play a crucial role in thin-film solar cells based on Cu(In,Ga)(S,Se){sub 2}, both for long-term stability and short air exposure during production. For a better understanding of such effects, Cu(In,Ga)(S,Se){sub 2} absorber surfaces were investigated by x-ray photoelectron and Auger electron spectroscopy after exposure to different environmental conditions. Identical absorbers were stored in a nitrogen atmosphere, in damp heat, and under ambient conditions for up to 14 days. We find varying degrees of diffusion of sulfur, copper, and sodium towards the surface, with potential impact on the electronic surface structure (band gap) and the properties of the interface to a buffer layer in a solar cell device. Furthermore, we observe an oxidation (in decreasing order) of indium, copper, and selenium (but no oxidation of sulfur). And finally, varying amounts of carbon- and oxygen-containing adsorbates are found. In particular, the findings suggest that, for ambient air exposure, sodium carbonate is formed at the surface.

  11. Effect of heat-treatment conditions on the structure and physicomechanical and chemical properties of a Ni-Cr-Cu-Ti maraging steel

    NASA Astrophysics Data System (ADS)

    Bannykh, O. A.; Berezovskaya, V. V.

    2007-06-01

    The effects of quenching (from 950°C or from 950 and 850°C) and the aging conditions on the structure, properties, and delayed fracture (DF) of 03Kh11N10M2DT maraging steel has been studied by dilatometry, X-ray diffraction, and fracture tests. The DF-crack growth rate is maximal after aging at 400°C irrespective of the quenching conditions, and the corrosion rate is maximal after aging at 350 400°C in the case of single quenching and at 350°C after double quenching. The kinetics and mechanism of the early stages of the decomposition of a supersaturated α solid solution are investigated by electrical-resistance measurements and transmission electron microscopy. In the state after single quenching, aging occurs in two stages at all isothermal heat treatments; in the state after double quenching, aging occurs in one stage at a time exponent n = 0.2 in the Johnson-Mehl equation. Upon aging at 400°C, the intermediate ordered Fe3(Ni,Ti) phase with a complex cubic lattice precipitates, and the intermetallic compound Ni3Ti precipitates upon subsequent aging. Moreover, copper-rich ɛ-phase precipitates form only in the case of single quenching. The substantial increase in the crack growth rate during DF with n < 0.2 is likely to be caused by the formation of Guinier-Preston zones enriched in nickel and titanium.

  12. Role of chemical composition in the enhanced catalytic activity of Pt-based alloyed ultrathin nanowires for the hydrogen oxidation reaction under alkaline conditions

    DOE PAGESBeta

    Megan E. Scofield; Wong, Stanislaus S.; Zhou, Yuchen; Yue, Shiyu; Wang, Lei; Su, Dong; Tong, Xiao; Vukmirovic, Miomir B.; Adzic, Radoslav R.

    2016-05-19

    With the increased interest in the development of hydrogen fuel cells as a plausible alternative to internal combustion engines, recent work has focused on creating alkaline fuel cells (AFC), which employ an alkaline environment. Working in alkaline as opposed to acidic media yields a number of tangible benefits, including (i) the ability to use cheaper and plentiful precious-metal-free catalysts, due to their increased stability, (ii) a reduction in the amount of degradation and corrosion of Pt-based catalysts, and (iii) a longer operational lifetime for the overall fuel cell configuration. However, in the absence of Pt, no catalyst has achieved activitiesmore » similar to those of Pt. Herein, we have synthesized a number of crystalline ultrathin PtM alloy nanowires (NWs) (M = Fe, Co, Ru, Cu, Au) in order to replace a portion of the costly Pt metal without compromising on activity while simultaneously adding in metals known to exhibit favorable synergistic ligand and strain effects with respect to the host lattice. In fact, our experiments confirm theoretical insights about a clear and correlative dependence between measured activity and chemical composition. We have conclusively demonstrated that our as-synthesized alloy NW catalysts yield improved hydrogen oxidation reaction (HOR) activities as compared with a commercial Pt standard as well as with our as-synthesized Pt NWs. The Pt7Ru3 NW system, in particular, quantitatively achieved an exchange current density of 0.493 mA/cm2, which is higher than the corresponding data for Pt NWs alone. In addition, the HOR activities follow the same expected trend as their calculated hydrogen binding energy (HBE) values, thereby confirming the critical importance and correlation of HBE with the observed activities.« less

  13. High-sensitivity nuclear magnetic resonance at Giga-Pascal pressures: a new tool for probing electronic and chemical properties of condensed matter under extreme conditions.

    PubMed

    Meier, Thomas; Haase, Jürgen

    2014-01-01

    Nuclear Magnetic Resonance (NMR) is one of the most important techniques for the study of condensed matter systems, their chemical structure, and their electronic properties. The application of high pressure enables one to synthesize new materials, but the response of known materials to high pressure is a very useful tool for studying their electronic structure and developing theories. For example, high-pressure synthesis might be at the origin of life; and understanding the behavior of small molecules under extreme pressure will tell us more about fundamental processes in our universe. It is no wonder that there has always been great interest in having NMR available at high pressures. Unfortunately, the desired pressures are often well into the Giga-Pascal (GPa) range and require special anvil cell devices where only very small, secluded volumes are available. This has restricted the use of NMR almost entirely in the past, and only recently, a new approach to high-sensitivity GPa NMR, which has a resonating micro-coil inside the sample chamber, was put forward. This approach enables us to achieve high sensitivity with experiments that bring the power of NMR to Giga-Pascal pressure condensed matter research. First applications, the detection of a topological electronic transition in ordinary aluminum metal and the closing of the pseudo-gap in high-temperature superconductivity, show the power of such an approach. Meanwhile, the range of achievable pressures was increased tremendously with a new generation of anvil cells (up to 10.1 GPa), that fit standard-bore NMR magnets. This approach might become a new, important tool for the investigation of many condensed matter systems, in chemistry, geochemistry, and in physics, since we can now watch structural changes with the eyes of a very versatile probe. PMID:25350694

  14. Improvement of chemical monitoring of water-chemistry conditions at thermal power stations based on electric conductivity and pH measurements

    NASA Astrophysics Data System (ADS)

    Larin, A. B.; Larin, B. M.

    2016-05-01

    The increased requirements to the quality of the water heat conductor for working superhigh (SHP) and supercritical (SCP) pressure power plants and promising units, including combined-cycle gas turbine (CCGT) units and power plants with ultrasupercritical parameters (USCPs), can largely be satisfied through specific electric conductivity and pH measurements for cooled heat conductor samples combined with calculations of ionic equilibria and indirect measurements of several specified and diagnostic parameters. The possibility of calculating the ammonia and chloride concentrations and the total concentration of hardness and sodium cations in the feed water of drum-type boilers and the phosphate and salt contents in boiler water was demonstrated. An equation for evaluating the content of potentially acid substances in the feed water of monotube boilers was suggested. The potential of the developed procedure for evaluating the state of waterchemistry conditions (WCCs) in power plants with CCGT units was shown.

  15. Characterization of selected biological, chemical, and physical conditions at fixed sites in the Upper Colorado River basin, Colorado, 1995-98

    USGS Publications Warehouse

    Deacon, Jeffrey R.; Mize, Scott V.; Spahr, Norman E.

    1999-01-01

    Biological community samples were collected at 15 sites in the Upper Colorado River Basin (UCOL) in Colorado as part of the National Water-Quality Assessment (NAWQA) Program. Sites sampled in two physiographic provinces, the Southern Rocky Mountains and the Colorado Plateau, represented agriculture, mining, urban and recreation, and mixed land uses and background conditions. Nine measures of water quality, which include information on nutrients, specific conductance (a surrogate for salinity), trace elements in streambed sediment, pesticides in fish tissue, fish communities, and macroinvertebrate richness and composition and stream habitat were used for comparisons among sites within the two physiographic provinces. Sampling sites from three other NAWQA study units?the Rio Grande Valley, the South Platte River Basin, and the Upper Snake River Basin study units?were categorized on the basis of land use and stream size in order to develop a larger data set for comparison to sites in the UCOL. Three categories of land use?forested (includes mining, urban and recreation, and background), agriculture, and mixed?were used for comparison to the UCOL fixed sites. Results indicated that all sites other than the Colorado River below Baker Gulch (a background site) showed some water-quality characteristics to be significantly affected. Results indicated that the concentrations of cadmium and zinc in streambed sediment at mining land-use sites in the Southern Rocky Mountains physiographic province generally were orders of magnitude higher than streambed-sediment concentrations at the background site. Streambed-sediment concentrations at mining land-use sites in the UCOL were greater than the 75th percentile of concentrations from sites in the three other NAWQA study units. Fish communities and habitat conditions were degraded at mining land-use sites compared to the background site. Ephemeroptera, Plecoptera, and Trichoptera (EPT) richness and the percentage of EPT were lower

  16. EVOLUTION OF CHEMICAL CONDITIONS AND ESTIMATED PLUTONIUM SOLUBILITY IN THE RESIDUAL WASTE LAYER DURING POST-CLOSURE AGING OF TANK 18

    SciTech Connect

    Denham, M.

    2012-02-29

    evolution. In Denham (2007, Rev. 1), the solubilities in the oxidized regions were estimated at Eh values in equilibrium with dissolved oxygen. Here, these are considered to be maximum possible solubilities because Eh values are unlikely to be in equilibrium with dissolved oxygen. More realistic Eh values are estimated here and plutonium solubilities calculated at these are considered more realistic. Apparent solubilities of plutonium that coprecipitated with iron phases are estimated from Pu:Fe ratios in Tank 18 residual waste and the solubilities of the host iron phases. The estimated plutonium solubilities are shown. Uncertainties in the grout simulations and plutonium solubility estimates are discussed. The primary uncertainty in the grout simulations is that little is known about the physical state of the grout as it ages. The simulations done here are pertinent to a porous medium, which may or may not be applicable to fractured grout, depending on the degree and nature of the fractures. Other uncertainties that are considered are the assumptions about the reducing capacity imparted by blast furnace slag, the effects of varying dissolved carbon dioxide and oxygen concentrations, and the treatment of silica in the simulations. The primary uncertainty in the estimates of plutonium solubility is that little is known about the exact form of plutonium in the residual waste. Other uncertainties include those inherent in the thermodynamic data, pH variations from those estimated in the grout simulations, the effects of the treatment of silica in the grout simulations, and the effect of varying total dissolved carbonate concentrations. The objective of this document is to update the model for solubility controls on release of plutonium from residual waste in closed F-Area waste tanks. The update is based on new information including a new proposed grout formulation, chemical analysis of Tank 18 samples and more current thermodynamic data for plutonium and grout minerals. In

  17. Determining the microwave coupling and operational efficiencies of a microwave plasma assisted chemical vapor deposition reactor under high pressure diamond synthesis operating conditions

    SciTech Connect

    Nad, Shreya; Gu, Yajun; Asmussen, Jes

    2015-07-15

    The microwave coupling efficiency of the 2.45 GHz, microwave plasma assisted diamond synthesis process is investigated by experimentally measuring the performance of a specific single mode excited, internally tuned microwave plasma reactor. Plasma reactor coupling efficiencies (η) > 90% are achieved over the entire 100–260 Torr pressure range and 1.5–2.4 kW input power diamond synthesis regime. When operating at a specific experimental operating condition, small additional internal tuning adjustments can be made to achieve η > 98%. When the plasma reactor has low empty cavity losses, i.e., the empty cavity quality factor is >1500, then overall microwave discharge coupling efficiencies (η{sub coup}) of >94% can be achieved. A large, safe, and efficient experimental operating regime is identified. Both substrate hot spots and the formation of microwave plasmoids are eliminated when operating within this regime. This investigation suggests that both the reactor design and the reactor process operation must be considered when attempting to lower diamond synthesis electrical energy costs while still enabling a very versatile and flexible operation performance.

  18. Determining the microwave coupling and operational efficiencies of a microwave plasma assisted chemical vapor deposition reactor under high pressure diamond synthesis operating conditions.

    PubMed

    Nad, Shreya; Gu, Yajun; Asmussen, Jes

    2015-07-01

    The microwave coupling efficiency of the 2.45 GHz, microwave plasma assisted diamond synthesis process is investigated by experimentally measuring the performance of a specific single mode excited, internally tuned microwave plasma reactor. Plasma reactor coupling efficiencies (η) > 90% are achieved over the entire 100-260 Torr pressure range and 1.5-2.4 kW input power diamond synthesis regime. When operating at a specific experimental operating condition, small additional internal tuning adjustments can be made to achieve η > 98%. When the plasma reactor has low empty cavity losses, i.e., the empty cavity quality factor is >1500, then overall microwave discharge coupling efficiencies (η(coup)) of >94% can be achieved. A large, safe, and efficient experimental operating regime is identified. Both substrate hot spots and the formation of microwave plasmoids are eliminated when operating within this regime. This investigation suggests that both the reactor design and the reactor process operation must be considered when attempting to lower diamond synthesis electrical energy costs while still enabling a very versatile and flexible operation performance. PMID:26233399

  19. Determining the microwave coupling and operational efficiencies of a microwave plasma assisted chemical vapor deposition reactor under high pressure diamond synthesis operating conditions

    NASA Astrophysics Data System (ADS)

    Nad, Shreya; Gu, Yajun; Asmussen, Jes

    2015-07-01

    The microwave coupling efficiency of the 2.45 GHz, microwave plasma assisted diamond synthesis process is investigated by experimentally measuring the performance of a specific single mode excited, internally tuned microwave plasma reactor. Plasma reactor coupling efficiencies (η) > 90% are achieved over the entire 100-260 Torr pressure range and 1.5-2.4 kW input power diamond synthesis regime. When operating at a specific experimental operating condition, small additional internal tuning adjustments can be made to achieve η > 98%. When the plasma reactor has low empty cavity losses, i.e., the empty cavity quality factor is >1500, then overall microwave discharge coupling efficiencies (ηcoup) of >94% can be achieved. A large, safe, and efficient experimental operating regime is identified. Both substrate hot spots and the formation of microwave plasmoids are eliminated when operating within this regime. This investigation suggests that both the reactor design and the reactor process operation must be considered when attempting to lower diamond synthesis electrical energy costs while still enabling a very versatile and flexible operation performance.

  20. Quantitative evaluation by attenuated total reflectance infrared (ATR-FTIR) spectroscopy of the chemical composition of decayed wood preserved in waterlogged conditions.

    PubMed

    Pizzo, Benedetto; Pecoraro, Elisa; Alves, Ana; Macchioni, Nicola; Rodrigues, José Carlos

    2015-01-01

    This paper reports on the assessment of lignin and holocellulose by means of ATR-FTIR analysis and multivariate PLS regression. The analysis was conducted on 59 samples coming from different excavations where wood had been preserved in waterlogged conditions. A range of results from different wood species (Alnus sp.p., Cupressus sempervirens, Larix decidua, Picea abies, Pinus sp.p., Quercus sp.p., Ulmus sp.p.), states of preservation, waterlogged environments, and burial times are presented. A calibration model was selected after comparing different reference data (samples extracted and not-extracted, and ash-rich and ash-free bases of calculation for the calibration values), and two different post-acquisition spectroscopic manipulations (both in terms of normalisation procedures and of spectral ranges used for the calibration). Results showed that the best models were different depending on which considered component (lignin or holocellulose) was measured and to which data set (softwood or hardwood) the samples belonged. It is shown that the predictive ability of the models is affected by high ash content (too contaminated samples had to be excluded in order to attain good results, because of excessive overlapping of bands related to the inorganic fraction) but not by the preliminary extraction of sample. Furthermore, the stability of best models is also demonstrated and a procedure of external validation carried out on an external set of samples confirmed the general validity of the identified models. PMID:25281067

  1. Reinvestigation of hybrid organic-inorganic materials based on molybdate and piperazininum cations: Influence of the synthesis conditions on the chemical composition and characterizations of the photochromic properties

    SciTech Connect

    Coue, Violaine; Dessapt, Remi Bujoli-Doeuff, Martine; Evain, Michel; Jobic, Stephane

    2008-05-15

    The reactivity of the [Mo{sub 7}O{sub 24}]{sup 6-} anion towards the structure directing-reagent piperazine (pipz) has been investigated and new synthetic routes to achieve the known (H{sub 2}pipz){sub 3}[Mo{sub 8}O{sub 27}] 1, (H{sub 2}pipz)[Mo{sub 3}O{sub 10}].H{sub 2}O 2, and (H{sub 2}pipz)[Mo{sub 5}O{sub 16}] 3 molybdenum(VI) containing compounds are proposed. The role of the pH on the stabilization of the different compounds and their interconversion pathways is discussed. Compounds 1 and 2 show photochromic behavior under UV excitation, related to the particular organization of the organic component around the mineral framework. Their optical properties are reported and commented. - Graphical abstract: Three organic-inorganic hybrid materials have been prepared from the investigations of the [Mo{sub 7}O{sub 24}]{sup 6-}/piperazine system in hydrothermal conditions. The role of the pH on the stabilization of the different polyoxomolybdate blocks in the materials i.e. 1/({infinity}) [Mo{sub 3}O{sub 10}]{sup 2-} and 1/({infinity}) [Mo{sub 8}O{sub 27}]{sup 6-} chains and 2/({infinity}) [Mo{sub 5}O{sub 16}]{sup 2-} layer has been investigated.

  2. Effects of interlayer growth condition on the transport properties of heterostructures with InGaN channel grown on sapphire by metal organic chemical vapor deposition

    SciTech Connect

    Zhang, Yachao; Zhou, Xiaowei; Xu, Shengrui; Wang, Zhizhe; Zhao, Yi; Zhang, Jinfeng; Chen, Dazheng; Zhang, Jincheng Hao, Yue

    2015-04-13

    The effects of AlN interlayer growth condition on the properties of InAlN/InGaN heterostructures are investigated in detail. Since the properties of InGaN channel are different from the traditional GaN channel, two-step AlN interlayer is proposed, which is proven to be more suitable for the InGaN channel heterostructures than the interlayers grown at constant temperature. Test results show that two-step AlN interlayer can not only significantly improve the interface morphology between the InGaN channel and barrier layers but also make an effective protection of the high-quality InGaN channel. The electron mobility of the InAlN/InGaN heterostructure with two-step AlN interlayer achieves 890 cm{sup 2}/V s with a high two-dimensional-electron-gas density of 1.78 × 10{sup 13 }cm{sup −2}. The gratifying results indicate that the InGaN channel heterostructure with two-step interlayer is a promising candidate for microwave power devices.

  3. Chemical bath deposition of ZnO nanowires at near-neutral pH conditions without hexamethylenetetramine (HMTA): understanding the role of HMTA in ZnO nanowire growth.

    PubMed

    McPeak, Kevin M; Le, Thinh P; Britton, Nathan G; Nickolov, Zhorro S; Elabd, Yossef A; Baxter, Jason B

    2011-04-01

    Chemical bath deposition (CBD) is an inexpensive and reproducible method for depositing ZnO nanowire arrays over large areas. The aqueous Zn(NO(3))(2)-hexamethylenetetramine (HMTA) chemistry is one of the most common CBD chemistries for ZnO nanowire synthesis, but some details of the reaction mechanism are still not well-understood. Here, we report the use of in situ attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy to study HMTA adsorption from aqueous solutions onto ZnO nanoparticle films and show that HMTA does not adsorb on ZnO. This result refutes earlier claims that the anisotropic morphology arises from HMTA adsorbing onto and capping the ZnO {10 1 0} faces. We conclude that the role of HMTA in the CBD of ZnO nanowires is only to control the saturation index of ZnO. Furthermore, we demonstrate the first deposition of ZnO nanowire arrays at 90 °C and near-neutral pH conditions without HMTA. Nanowires were grown using the pH buffer 2-(N-morpholino)ethanesulfonic acid (MES) and continuous titratation with KOH to maintain the same pH conditions where growth with HMTA occurs. This semi-batch synthetic method opens many new opportunities to tailor the ZnO morphology and properties by independently controlling temperature and pH. PMID:21361384

  4. FLUE GAS CONDITIONING

    EPA Science Inventory

    The report gives results of a survey of available flue gas conditioning agents and user experience. Many existing chemicals have been used as conditioning agents in power plants or have been studied in the laboratory as potential agents. The particle collection efficiency of an e...

  5. Biomass - chemicals

    SciTech Connect

    Kovaly, K.A.

    1982-08-01

    A host of industrial chemicals, specialty items, solvents, plastics, elastomers, fibers and films can be produced from agricultural crops, wood, paper mill wastes, food processing wastes, municipal waste and sewage. Existing chemical processes based on readily renewable plant materials are reviewed. These include ethanol and acetone-butanol fermentations, oilseed chemicals, furfural and cellulosics. (Refs. 16).

  6. Chemical Leukoderma.

    PubMed

    Bonamonte, Domenico; Vestita, Michelangelo; Romita, Paolo; Filoni, Angela; Foti, Caterina; Angelini, Gianni

    2016-01-01

    Chemical leukoderma, often clinically mimicking idiopathic vitiligo and other congenital and acquired hypopigmentation, is an acquired form of cutaneous pigment loss caused by exposure to a variety of chemicals that act through selective melanocytotoxicity. Most of these chemicals are phenols and aromatic or aliphatic catechols derivatives. These chemicals, however, are harmful for melanocytes in individuals with an individual susceptibility. Nowadays, chemical leukoderma is fairly common, caused by common domestic products. The presence of numerous acquired confetti- or pea-sized macules is clinically characteristic of chemical leukoderma, albeit not diagnostic. Other relevant diagnostic elements are a history of repeated exposure to a known or suspected depigmenting agent at the sites of onset and a macules distribution corresponding to sites of chemical exposure. Spontaneous repigmentation has been reported when the causative agent is avoided; the repigmentation process is perifollicular and gradual, taking place for a variable period of weeks to months. PMID:27172302

  7. DEMONSTRATION OF THE DWPF FLOWSHEET IN THE SRNL SHIELDED CELLS USING ARP PRODUCT SIMULANT AND SB4 TANK 40 SLUDGE SLURRY

    SciTech Connect

    Lambert, D; John Pareizs, J; Bradley Pickenheim, B; Cj Bannochie, C; Michael Stone, M; Damon Click, D; Erich Hansen, E; Kim Crapse, K; David Hobbs, D

    2008-05-14

    The radioactive startup of two new SRS processing facilities, the Actinide Removal Process (ARP) and the Modular Caustic-Side-Solvent-Extraction Unit (MCU) will add two new waste streams to the Defense Waste Processing Facility (DWPF). The ARP will remove actinides from the 5.6 M salt solution resulting in a sludge-like product that is roughly half monosodium titanate (MST) insoluble solids and half sludge insoluble solids. The ARP product will be added to the Sludge Receipt and Adjustment Tank (SRAT) at boiling and dewatered prior to pulling a SRAT receipt sample. The cesium rich MCU stream will be added to the SRAT at boiling after both formic and nitric acid have been added and the SRAT contents concentrated to the appropriate endpoint. A concern was raised by an external hydrogen review panel that the actinide loaded MST could act as a catalyst for hydrogen generation (Mar 15, 2007 report, Recommendation 9). Hydrogen generation, and it's potential to form a flammable mixture in the off-gas, under SRAT and Slurry Mix Evaporator (SME) processing conditions has been a concern since the discovery that noble metals catalyze the decomposition of formic acid. Radiolysis of water also generates hydrogen, but the radiolysis rate is orders of magnitude lower than the noble metal catalyzed generation. As a result of the concern raised by the external hydrogen review panel, hydrogen generation was a prime consideration in this experiment. Testing was designed to determine whether the presence of the irradiated ARP simulant containing MST caused uncontrolled or unexpected hydrogen production during experiments simulating the DWPF Chemical Process Cell (CPC) due to activation of titanium. A Shielded Cells experiment, SC-5, was completed using SB4 sludge from Tank 405 combined with an ARP product produced from simulants by SRNL researchers. The blend of sludge and MST was designed to be prototypic of planned DWPF SRAT and SME cycles. As glass quality was not an objective in

  8. [Chemical weapons and chemical terrorism].

    PubMed

    Nakamura, Katsumi

    2005-10-01

    Chemical Weapons are kind of Weapons of Mass Destruction (WMD). They were used large quantities in WWI. Historically, large quantities usage like WWI was not recorded, but small usage has appeared now and then. Chemical weapons are so called "Nuclear weapon for poor countrys" because it's very easy to produce/possession being possible. They are categorized (1) Nerve Agents, (2) Blister Agents, (3) Cyanide (blood) Agents, (4) Pulmonary Agents, (5) Incapacitating Agents (6) Tear Agents from the viewpoint of human body interaction. In 1997 the Chemical Weapons Convention has taken effect. It prohibits chemical weapons development/production, and Organization for the Prohibition of Chemical Weapons (OPCW) verification regime contributes to the chemical weapons disposal. But possibility of possession/use of weapons of mass destruction by terrorist group represented in one by Matsumoto and Tokyo Subway Sarin Attack, So new chemical terrorism countermeasures are necessary. PMID:16296384

  9. Chemical microsensors

    DOEpatents

    Li, DeQuan; Swanson, Basil I.

    1995-01-01

    An article of manufacture is provided including a substrate having an oxide surface layer and a selective thin film of a cyclodextrin derivative chemically bound upon said substrate, said film is adapted for the inclusion of a selected organic compound therewith. Such an article can be either a chemical sensor capable of detecting a resultant mass change from inclusion of the selected organic compound or a chemical separator capable of reversibly selectively separating a selected organic compound.

  10. An experimental study of magnesite dissolution rates at neutral to alkaline conditions and 150 and 200 °C as a function of pH, total dissolved carbonate concentration, and chemical affinity

    NASA Astrophysics Data System (ADS)

    Saldi, Giuseppe D.; Schott, Jacques; Pokrovsky, Oleg S.; Oelkers, Eric H.

    2010-11-01

    Steady-state magnesite dissolution rates were measured in mixed-flow reactors at 150 and 200 °C and 4.6 < pH < 8.4, as a function of ionic strength (0.001 M ⩽ I ⩽ 1 M), total dissolved carbonate concentration (10 -4 M < ΣCO 2 < 0.1 M), and distance from equilibrium. Rates were found to increase with increasing ionic strength, but decrease with increasing temperature from 150 to 200 °C, pH, and aqueous CO 32- activity. Measured rates were interpreted using the surface complexation model developed by Pokrovsky et al. (1999a) in conjunction with transition state theory ( Eyring, 1935). Within this formalism, magnesite dissolution rates are found to be consistent with r=k{>MgOH2+}41-exp (-4ART), where rd represents the BET surface area normalized dissolution rate, {>MgOH2+} stands for the concentration of hydrated magnesium centers on the magnesite surface, kMg designates a rate constant, A refers to the chemical affinity of the overall reaction, R denotes the gas constant, and T symbolizes absolute temperature. Within this model decreasing rates at far-from-equilibrium conditions (1) at constant pH with increasing temperature and (2) at constant temperature with increasing pH and ΣCO 2 stem from a corresponding decrease in {>MgOH2+}. This decrease in {>MgOH2+} results from the increasing stability of the >MgCO3- and >MgOH° surface species with increasing temperature, pH and CO 32- activity. The decrease in constant pH dissolution rates yields negative apparent activation energies. This behavior makes magnesite resistant to re-dissolution if formed as part of mineral carbon sequestration efforts in deep geologic formations.

  11. Investigating Chemical and Thermodynamic Conditions that Determine the Aerosol Inorganic Nitrate Size Distribution: Insights from Speciated PM2.5 and PM10 Hourly Datasets from an Urban Site

    NASA Astrophysics Data System (ADS)

    Griffith, S. M.; Huang, X. H. H.; Louie, P. K. K.; Yu, J. Z.

    2015-12-01

    Nitric acid (HNO3), the gas-phase precursor to aerosol nitrate is known to rapidly transfer to aerosols where NH4+ is in excess to SO42- present in the aerosol, but the HNO3 is also subject to the slower uptake onto sea salt and dust laden particles. Understanding the competition between these routes is necessary to predict the NO3- distribution and impact on aerosols. In this study, we investigated the conditions leading to predominant fine or coarse mode aerosol nitrate using an hourly MARGA 2S dataset from an urban site in Hong Kong. The hourly dataset of inorganic ions (SO42-, NH4+, NO3-, Na+, Cl-, Ca2+, K+, Mg2+) in 2 size ranges (fine, < 2.5 μm; fine+coarse, < 10 μm) and water-soluble gases (HNO3, HCl, and NH3) spanning more than 1 year provides a rich trove for analyzing aerosol nitrate chemistry and the underlying mechanisms that ultimately determine the fraction of NO3- in the fine mode. The urban site in this study is initially characterized for seasonal environmental conditions and the aerosol chemical composition. The relationship between excess NH4+ and NO3- in the fine mode is detailed and contrasted with the influence on fine mode NO3- from uptake on sea salt and dust, which is typically relegated as a 'coarse-mode' mechanism. The distribution of NO3- in the fine and coarse modes is compared with the distribution of the other inorganic ions, where sea-salt ion (Na+, Mg2+) distributions yield the highest explained variability for the nitrate distributions. As a complement to that finding, the cation equivalency (excluding NH4+) in the coarse mode proves to be a crucial factor in leveraging the distribution away from fine mode nitrate. The uptake potential of the water-soluble gases is used to drive a mass transfer model and compare with thermodynamic equilibrium results. In the modeling, the partitioning cycles of fine and coarse mode aerosol nitrate highlight the dynamic relationship between NO3- and Cl- in both the fine and coarse modes, where the

  12. Chromosomal Conditions

    MedlinePlus

    ... 150 babies is born with a chromosomal condition. Down syndrome is an example of a chromosomal condition. Because ... all pregnant women be offered prenatal tests for Down syndrome and other chromosomal conditions. A screening test is ...

  13. Chemical preconcentrator

    DOEpatents

    Manginell, Ronald P.; Frye-Mason, Gregory C.

    2001-01-01

    A chemical preconcentrator is disclosed with applications to chemical sensing and analysis. The preconcentrator can be formed by depositing a resistive heating element (e.g. platinum) over a membrane (e.g. silicon nitride) suspended above a substrate. A coating of a sorptive material (e.g. a microporous hydrophobic sol-gel coating or a polymer coating) is formed on the suspended membrane proximate to the heating element to selective sorb one or more chemical species of interest over a time period, thereby concentrating the chemical species in the sorptive material. Upon heating the sorptive material with the resistive heating element, the sorbed chemical species are released for detection and analysis in a relatively high concentration and over a relatively short time period. The sorptive material can be made to selectively sorb particular chemical species of interest while not substantially sorbing other chemical species not of interest. The present invention has applications for use in forming high-sensitivity, rapid-response miniaturized chemical analysis systems (e.g. a "chem lab on a chip").

  14. Chemical sensors

    DOEpatents

    Lowell, Jr., James R.; Edlund, David J.; Friesen, Dwayne T.; Rayfield, George W.

    1991-01-01

    Sensors responsive to small changes in the concentration of chemical species are disclosed, comprising (a) a mechanochemically responsive polymeric film capable of expansion or contraction in response to a change in its chemical environment, operatively coupled to (b) a transducer capable of directly converting said expansion or contraction to a measurable electrical response.

  15. Chemical sensors

    DOEpatents

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

    1991-07-02

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

  16. Chemical Peels

    MedlinePlus

    ... the complications or potential side effects of a chemical peel? Temporary or permanent change in skin color, particularly for women on birth control pills, who subsequently become pregnant or have a history of brownish facial ... after having a chemical peel? All peels require some follow-up care: ...

  17. Chemical Emergencies

    MedlinePlus

    ... agents such as sarin and VX. Many hazardous chemicals are used in industry - for example, chlorine, ammonia, and benzene. Some can be made from everyday items such as household cleaners. Although there are no guarantees of safety during a chemical emergency, you can take actions to protect yourself. ...

  18. TREATMENT TANK OFF-GAS TESTING FOR THE ENHANCED CHEMICAL CLEANING PROCESS

    SciTech Connect

    Wiersma, B.

    2011-08-29

    The purpose of this activity was to provide a bounding estimate of the volume of hydrogen gas generated during Enhanced Chemical Cleaning (ECC) of residual sludge remaining in a Type I or Type II treatment tank as well as to provide results independent of the sludge volume in the waste tank to be cleaned. Previous testing to support Chemical Cleaning was based on a 20:1 oxalic acid to sludge ratio. Hydrogen gas evolution is the primary safety concern. Sealed vessel coupon tests were performed to estimate the hydrogen generation rate due to corrosion of carbon steel by 2.5 wt.% oxalic acid. These tests determined the maximum instantaneous hydrogen generation rate, the rate at which the generation rate decays, and the total hydrogen generated. These values were quantified based on a small scale methodology similar to the one described in WSRC-STI-2007-00209, Rev. 0. The measured rates support identified Safety Class functions. The tests were performed with ASTM A285 Grade C carbon steel coupons. Bounding conditions were determined for the solution environment. The oxalic acid concentration was 2.5 wt.% and the test temperature was 75 C. The test solution was agitated and contained no sludge simulant. Duplicate tests were performed and showed excellent reproducibility for the hydrogen generation rate and total hydrogen generated. The results showed that the hydrogen generation rate was initially high, but decayed rapidly within a couple of days. A statistical model was developed to predict the instantaneous hydrogen generation rate as a function of exposure time by combining both sets of data. An upper bound on the maximum hydrogen generation rate was determined from the upper 95% confidence limit. The upper bound confidence limit for the hydrogen generation rate is represented by the following equation. ln (G{sub v}) = -8.22-0.0584 t + 0.0002 t{sup 2}. This equation should be utilized to estimate the instantaneous hydrogen generation rate per unit surface area, G

  19. Unnecessary Chemicals

    ERIC Educational Resources Information Center

    Johnson, Anita

    1978-01-01

    Discusses the health hazards resulting from chemical additions of many common products such as cough syrups, food dyes, and cosmetics. Steps being taken to protect consumers from these health hazards are included. (MDR)

  20. Chemical sensors

    DOEpatents

    Lowell, Jr., James R.; Edlund, David J.; Friesen, Dwayne T.; Rayfield, George W.

    1992-01-01

    Sensors responsive to small changes in the concentration of chemical species are disclosed, comprising a mechanicochemically responsive polymeric film capable of expansion or contraction in response to a change in its chemical environment, either operatively coupled to a transducer capable of directly converting the expansion or contraction to a measurable electrical or optical response, or adhered to a second inert polymeric strip, or doped with a conductive material.

  1. Chemical sensors

    DOEpatents

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

    1992-06-09

    Sensors responsive to small changes in the concentration of chemical species are disclosed, comprising a mechanicochemically responsive polymeric film capable of expansion or contraction in response to a change in its chemical environment, either operatively coupled to a transducer capable of directly converting the expansion or contraction to a measurable electrical or optical response, or adhered to a second inert polymeric strip, or doped with a conductive material. 12 figs.

  2. Ab initio chemical kinetics for SiH2 + Si2H6 and SiH3 + Si2H5 reactions and the related unimolecular decomposition of Si3H8 under a-Si/H CVD conditions.

    PubMed

    Raghunath, P; Lin, M C

    2013-10-24

    The kinetics and mechanisms for SiH2 + Si2H6 and SiH3 + Si2H5 reactions and the related unimolecular decomposition of Si3H8 have been investigated by ab initio molecular orbital theory based on the QCISD(T)/CBS//QCISD/6-311++G(d,p) method in conjunction with quantum statistical variational Rice-Ramsperger-Kassel-Marcus (RRKM) calculations. For the barrierless radical association processes, their variational transition states have been characterized by the CASPT2//CASSCF method. The species involved in the study are known to coexist under CVD conditions. The results show that the association reaction of SiH2 and Si2H6 producing Si3H8 occurs by insertion via its lowest-energy path forming a loose hydrogen-bonding molecular complex with 8.3 kcal/mol binding energy; the reaction is exothermic by 55.0 kcal/mol. The chemically activated Si3H8 adduct can fragment by several paths, producing SiH4 + SiH3SiH (-0.7 kcal/mol), Si(SiH3)2 + H2 (-1.4 kcal/mol), and SiH3SiH2SiH + H2 (-1.4 kcal/mol). The predicted enthalpy changes as given agree well with available thermochemical data. Three other decomposition channels of Si3H8 occurring by Si-H or Si-Si breaking were found to be highly endothermic, and the reactions take place without a well-defined barrier. The heats of formation of Si3H8, SiH2SiH, Si2H4, i-Si3H7, n-Si3H7, Si(SiH3)2, and SiH3SiH2SiH have been predicted and found to be in close agreement with those available data in the literature. The product branching rate constants for SiH2 + Si2H6 and SiH3 + Si2H5 reactions and the thermal unimolecular decomposition of Si3H8 for all low-energy paths have been calculated with multichannel variational RRKM theory covering varying P,T conditions typically employed in PECVD and Cat-CVD processes for hydrogenated amorphous silicon (a-Si/H) film growth. The results were also found to be in good agreement with available kinetic data. Our kinetic results may be employed to model and control very large-area a-Si/H film growth for a

  3. Caustic-Side Solvent Extraction: Chemical and Physical Properties of the Optimized Solvent

    SciTech Connect

    Delmau, L.H.

    2002-10-08

    This work was undertaken to optimize the solvent used in the Caustic Side Solvent Extraction (CSSX) process and to measure key chemical and physical properties related to its performance in the removal of cesium from the alkaline high-level salt waste stored in tanks at the Savannah River Site. The need to adjust the solvent composition arose from the prior discovery that the previous baseline solvent was supersaturated with respect to the calixarene extractant. The following solvent-component concentrations in Isopar{reg_sign} L diluent are recommended: 0.007 M calix[4]arene-bis(tert-octylbenzo-crown-6) (BOBCalixC6) extractant, 0.75 M 1-(2,2,3,3-tetrafluoropropoxy)-3-(4-sec-butylphenoxy)-2-propanol (Cs-7SB) phase modifier, and 0.003 M tri-n-octylamine (TOA) stripping aid. Criteria for this selection included BOBCalixC6 solubility, batch cesium distribution ratios (D{sub Cs}), calculated flowsheet robustness, third-phase formation, coalescence rate (dispersion numbers), and solvent density. Although minor compromises within acceptable limits were made in flowsheet robustness and solvent density, significant benefits were gained in lower risk of third-phase formation and lower solvent cost. Data are also reported for the optimized solvent regarding the temperature dependence of D{sub Cs} in extraction, scrubbing, and stripping (ESS); ESS performance on recycle; partitioning of BOBCalixC6, Cs-7SB, and TOA to aqueous process solutions; partitioning of organic anions; distribution of metals; solvent phase separation at low temperatures; solvent stability to elevated temperatures; and solvent density and viscosity. Overall, the technical risk of the CSSX process has been reduced by resolving previously identified issues and raising no new issues.

  4. MICROWAVE TECHNOLOGY CHEMICAL SYNTHESIS APPLICATIONS

    EPA Science Inventory

    Microwave-accelerated chemical syntheses in various solvents as well as under solvent-free conditions have witnessed an explosive growth. The technique has found widespread application predominantly exploiting the inexpensive unmodified household microwave (MW) ovens although th...

  5. Chemical sensors

    SciTech Connect

    Hubbard, C.W.; Gordon, R.L.

    1987-05-01

    The revolution in analytical chemistry promised by recent developments in the field of chemical sensors has potential for significant positive impact on both research and production activities conducted by and for the Department of Energy. Analyses which were, in the past, performed only with a roomful of expensive equipment can now be performed with miniature solid-state electronic devices or small optical probes. Progress in the development of chemical sensors has been rapid, and the field is currently growing at a great rate. In accordance, Pacific Northwest Laboratory initiated a survey of recent literature so that contributors to active programs in research on analytical methods could be made aware of principles and applications of this new technology. This report presents the results of that survey. The sensors discussed here are divided into three types: micro solid-state devices, optical sensors, and piezoelectric crystal devices. The report is divided into three corresponding sections. The first section, ''Micro Solid-State Devices,'' discusses the design, operation, and application of electronic sensors that are produced in much the same way as standard solid-state electronic devices. The second section, ''Optrodes,'' covers the design and operation of chemical sensors that use fiber optics to detect chemically induced changes in optical properties. The final section, ''Piezoelectric Crystal Detectors,'' discusses two types of chemical sensors that depend on the changes in the properties of an oscillating piezoelectric crystal to detect the presence of certain materials. Advantages and disadvantages of each type of sensor are summarized in each section.

  6. Latest chemical peel innovations.

    PubMed

    Langsdon, Phillip R; Rodwell, David W; Velargo, Parker A; Langsdon, Carol H; Guydon, Amanda

    2012-05-01

    For decades, chemical peels have remained a trusted option for treatment of aging facial skin. However, emerging technologies are being adopted by many practitioners who may not have had sufficient opportunity to learn the art of chemical peeling. Properly performed peels can improve the condition of the skin, are less expensive than light-based machines, and exfoliate the skin without the thermal damage associated with light-based machines. This article presents a new variation of a trusted method, using a series of low-strength trichloroacetic acid peels and proper skin preparation that is cost-effective and produces excellent results in selected patients. PMID:22537780

  7. Chemical networks

    NASA Astrophysics Data System (ADS)

    Thi, Wing-Fai

    2015-09-01

    This chapter discusses the fundamental ideas of how chemical networks are build, their strengths and limitations. The chemical reactions that occur in disks combine the cold phase reactions used to model cold molecular clouds with the hot chemistry applied to planetary atmosphere models. With a general understanding of the different types of reactions that can occur, one can proceed in building a network of chemical reactions and use it to explain the abundance of species seen in disks. One on-going research subject is finding new paths to synthesize species either in the gas-phase or on grain surfaces. Specific formation routes for water or carbon monoxide are discussed in more details. 13th Lecture of the Summer School "Protoplanetary Disks: Theory and Modelling Meet Observations"

  8. Delicious Chemicals.

    ERIC Educational Resources Information Center

    Barry, Dana M.

    This paper presents an approach to chemistry and nutrition that focuses on food items that people consider delicious. Information is organized according to three categories of food chemicals that provide energy to the human body: (1) fats and oils; (2) carbohydrates; and (3) proteins. Minerals, vitamins, and additives are also discussed along with…

  9. Chemical sensors

    SciTech Connect

    Janata, J.; Josowicz, M.; DeVaney, D.M. )

    1994-06-15

    This review of chemical sensors contains the following topics of interest: books and reviews; reviews of sensors by their type; fabrication and selectivity; data processing; thermal sensors; mass sensors (fabrication, gas sensors, and liquid sensors); electrochemical sensors (potentiometric sensors, amperometric sensors, and conductometric sensors); and optical sensors (fabrication, liquid sensors, biosensors, and gas sensors). 795 refs., 1 tab.

  10. Chemical Mahjong

    ERIC Educational Resources Information Center

    Cossairt, Travis J.; Grubbs, W. Tandy

    2011-01-01

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

  11. Bioequivalent chemical steam sterilization indicators.

    PubMed

    Hirsch, A; Manne, S

    1984-01-01

    Biological indicators used to monitor steam sterilization cycles have two major shortcomings--the incubation period needed to determine if sterilization was accomplished, and the reliance on test packs for gathering information in each load. Chemical indicators do not suffer from these shortcomings. Chemical indicators can respond to time, temperature, and steam parameters to thus parallel the BI reaction. Nine commercially available chemical indicators and four biological indicators were evaluated under the conditions of dry heat, in a biological indicator-evaluator resistometer vessel, and in a hospital sterilizer. The results indicate that wider use of integrated chemical steam sterilization indicators is recommended. PMID:6493101

  12. Chemical substructure analysis in toxicology

    SciTech Connect

    Beauchamp, R.O. Jr.

    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.

  13. Biocatalysis for Biobased Chemicals

    PubMed Central

    de Regil, Rubén; Sandoval, Georgina

    2013-01-01

    The design and development of greener processes that are safe and friendly is an irreversible trend that is driven by sustainable and economic issues. The use of Biocatalysis as part of a manufacturing process fits well in this trend as enzymes are themselves biodegradable, require mild conditions to work and are highly specific and well suited to carry out complex reactions in a simple way. The growth of computational capabilities in the last decades has allowed Biocatalysis to develop sophisticated tools to understand better enzymatic phenomena and to have the power to control not only process conditions but also the enzyme’s own nature. Nowadays, Biocatalysis is behind some important products in the pharmaceutical, cosmetic, food and bulk chemicals industry. In this review we want to present some of the most representative examples of industrial chemicals produced in vitro through enzymatic catalysis. PMID:24970192

  14. Development of a process flowsheet for the elution of radiocesium from the TMI-2 (Three Mile Island Nuclear Power Station, Unit 2) makeup and purification demineralizers

    SciTech Connect

    Bond, W.D.; Knauer, J.B.; King, L.J.

    1987-01-01

    A process was developed for removing radiocesium from the two makeup and purification demineralizers at TMI-2 which had been highly contaminated as a result of the accident in 1979. Process conditions were established in hot-cell experiments using relatively small samples of the contaminated and degraded resins from the TMI-2 demineralizers. The process was designed to elute the radiocesium from the demineralizer resins and then resorb it onto the zeolite ion exchangers contained in the Submerged Demineralizer System (SDS). It was also required to limit the maximum cesium activities in the resin eluates (SDS feeds) so that the radiation field surrounding the pipelines would not be excessive. The process consisted of 17 stages of batch elution. In the initial stage, the resin was contacted with 0.18 M boric acid. Subsequent stages subjected the resin to increasing concentrations of sodium in NaH/sub 2/BO/sub 3/-H/sub 3/BO/sub 3/ solution (total boron = 0.35 M; and 1 M sodium hydroxide in the final stages). Simulated SDS tests with small zeolite beds (2 mL) showed that the eluates were compatible with SDS processing. Cesium was effectively sorbed (99.99%), and bed performance was unaffected by the presence of relatively small quantities of soluble organic resin degradation products (100 to 200 ppM total C) in the eluates. Also included in this report are radionuclide, elemental, and fissile isotopic analyses of the demineralizer samples, which may be of interest to investigators concerned with the phenomenological aspects of the TMI-2 accidents. 6 refs., 11 figs., 14 tabs.

  15. Chemical warfare

    PubMed Central

    Samuels, Richard Ian; Mattoso, Thalles Cardoso; Moreira, Denise D.O.

    2013-01-01

    Leaf-cutting ants are well known for their highly complex social organization, which provides them with a strong defense against parasites invading their colonies. Besides this attribute, these insects have morphological, physiological and structural characteristics further reinforcing the defense of their colonies. With the discovery of symbiotic bacteria present on the integument of leaf-cutting ants, a new line of defense was proposed and considered to be specific for the control of a specialized fungal parasite of the ants’ fungus gardens (Escovopsis). However, recent studies have questioned the specificity of the integumental bacteria, as they were also found to inhibit a range of fungi, including entomopathogens. The microbiota associated with the leaf-cutting ant gardens has also been proposed as another level of chemical defense, protecting the garden from parasite invasion. Here we review the chemical defense weaponry deployed by leaf-cutting ants against parasites of their fungus gardens and of the ants themselves. PMID:23795235

  16. Next generation Purex modeling by way of parallel processing with high performance computers

    SciTech Connect

    DeMuth, S.F.

    1993-08-01

    The Plutonium and Uranium Extraction (Purex) process is the predominant method used worldwide for solvent extraction in reprocessing spent nuclear fuels. Proper flowsheet design has a significant impact on the character of the process waste. Past Purex flowsheet modeling has been based on equilibrium conditions. It can be shown for the Purex process that optimum separation does not necessarily occur at equilibrium conditions. The next generation Purex flowsheet models should incorporate the fundamental diffusion and chemical kinetic processes required to study time-dependent behavior. Use of parallel processing with high-performance computers will permit transient multistage and multispecies design calculations based on mass transfer with simultaneous chemical reaction models. This paper presents an applicable mass transfer with chemical reaction model for the Purex system and presents a parallel processing solution methodology.

  17. Enhanced Chemical Cleaning: A New Process for Chemically Cleaning Savannah River Waste Tanks

    SciTech Connect

    Ketusky, Edward; Spires, Renee; Davis, Neil

    2009-02-11

    At the Savannah River Site (SRS) there are 49 High Level Waste (HLW) tanks that eventually must be emptied, cleaned, and closed. The current method of chemically cleaning SRS HLW tanks, commonly referred to as Bulk Oxalic Acid Cleaning (BOAC), requires about a half million liters (130,000 gallons) of 8 weight percent (wt%) oxalic acid to clean a single tank. During the cleaning, the oxalic acid acts as the solvent to digest sludge solids and insoluble salt solids, such that they can be suspended and pumped out of the tank. Because of the volume and concentration of acid used, a significant quantity of oxalate is added to the HLW process. This added oxalate significantly impacts downstream processing. In addition to the oxalate, the volume of liquid added competes for the limited available tank space. A search, therefore, was initiated for a new cleaning process. Using TRIZ (Teoriya Resheniya Izobretatelskikh Zadatch or roughly translated as the Theory of Inventive Problem Solving), Chemical Oxidation Reduction Decontamination with Ultraviolet Light (CORD-UV{reg_sign}), a mature technology used in the commercial nuclear power industry was identified as an alternate technology. Similar to BOAC, CORD-UV{reg_sign} also uses oxalic acid as the solvent to dissolve the metal (hydr)oxide solids. CORD-UV{reg_sign} is different, however, since it uses photo-oxidation (via peroxide/UV or ozone/UV to form hydroxyl radicals) to decompose the spent oxalate into carbon dioxide and water. Since the oxalate is decomposed and off-gassed, CORD-UV{reg_sign} would not have the negative downstream oxalate process impacts of BOAC. With the oxalate destruction occurring physically outside the HLW tank, re-precipitation and transfer of the solids, as well as regeneration of the cleaning solution can be performed without adding additional solids, or a significant volume of liquid to the process. With a draft of the pre-conceptual Enhanced Chemical Cleaning (ECC) flowsheet, taking full

  18. Chemical lasers

    NASA Astrophysics Data System (ADS)

    Khariton, Y.

    1984-08-01

    The application and the advances of quantum electronics, specifically, of optical quantum generators lasers is reviewed. Materials are cut, their surfaces are machined, chemical transformations of substances are carried out, surgical operations are performed, data are transmitted, three dimensional images are produced and the content of microimpurities, in the atmosphere, are analyzed by use of a beam. Laser technology is used in conducting investigations in the most diverse fields of the natural and technical sciences from controlled thermonuclear fusion to genetics. Many demands are placed on lasers as sources of light energy. The importance of low weight, compactness of the optical generator and the efficiency of energy conversion processes is emphasized.

  19. Metal-Organic Chemical Vapor Deposition (MOCVD) Synthesis of Heteroepitaxial Pr0.7Ca0.3MnO3 Films: Effects of Processing Conditions on Structural/Morphological and Functional Properties.

    PubMed

    Catalano, Maria R; Cucinotta, Giuseppe; Schilirò, Emanuela; Mannini, Matteo; Caneschi, Andrea; Lo Nigro, Raffaella; Smecca, Emanuele; Condorelli, Guglielmo G; Malandrino, Graziella

    2015-08-01

    Calcium-doped praseodymium manganite films (Pr0.7Ca0.3MnO3, PCMO) were prepared by metal-organic chemical vapor deposition (MOCVD) on SrTiO3 (001) and SrTiO3 (110) single-crystal substrates. Structural characterization through X-ray diffraction (XRD) measurements and transmission electron microscopy (TEM) analyses confirmed the formation of epitaxial PCMO phase films. Energy dispersive X-ray (EDX) and X-ray photoelectron spectroscopy (XPS) characterization was used to confirm lateral and vertical composition and the purity of the deposited films. Magnetic measurements, obtained in zero-field-cooling (ZFC) and field-cooling (FC) modes, provided evidence of the presence of a ferromagnetic (FM) transition temperature, which was correlated to the transport properties of the film. The functional properties of the deposited films, combined with the structural and chemical characterization collected data, indicate that the MOCVD approach represents a suitable route for the growth of pure, good quality PCMO for the fabrication of novel spintronic devices. PMID:26478849

  20. Metal-Organic Chemical Vapor Deposition (MOCVD) Synthesis of Heteroepitaxial Pr0.7Ca0.3MnO3 Films: Effects of Processing Conditions on Structural/Morphological and Functional Properties

    PubMed Central

    Catalano, Maria R; Cucinotta, Giuseppe; Schilirò, Emanuela; Mannini, Matteo; Caneschi, Andrea; Lo Nigro, Raffaella; Smecca, Emanuele; Condorelli, Guglielmo G; Malandrino, Graziella

    2015-01-01

    Calcium-doped praseodymium manganite films (Pr0.7Ca0.3MnO3, PCMO) were prepared by metal-organic chemical vapor deposition (MOCVD) on SrTiO3 (001) and SrTiO3 (110) single-crystal substrates. Structural characterization through X-ray diffraction (XRD) measurements and transmission electron microscopy (TEM) analyses confirmed the formation of epitaxial PCMO phase films. Energy dispersive X-ray (EDX) and X-ray photoelectron spectroscopy (XPS) characterization was used to confirm lateral and vertical composition and the purity of the deposited films. Magnetic measurements, obtained in zero-field-cooling (ZFC) and field-cooling (FC) modes, provided evidence of the presence of a ferromagnetic (FM) transition temperature, which was correlated to the transport properties of the film. The functional properties of the deposited films, combined with the structural and chemical characterization collected data, indicate that the MOCVD approach represents a suitable route for the growth of pure, good quality PCMO for the fabrication of novel spintronic devices. PMID:26478849

  1. Chemical Soil Physics Phenomena for Chemical Sensing of Buried UXO

    SciTech Connect

    Phelan, James, M.; Webb, Stephen W.

    1999-06-14

    Technology development efforts are under way to apply chemical sensors to discriminate inert ordnance and clutter from live munitions that remain a threat to reutilization of military ranges. However, the chemical signature is affected by multiple environmental phenomena that can enhance or reduce its presence and transport behavior, and can affect the distribution of the chemical signature in the environment. For example, the chemical can be present in the vapor, aqueous, and solid phases. The distribution of the chemical among these phases, including the spatial distribution, is key in designing appropriate detectors, e.g., gas, aqueous or solid phase sampling instruments. A fundamental understanding of the environmental conditions that affect the chemical signature is needed to describe the favorable and unfavorable conditions of a chemical detector based survey to minimize the consequences of a false negative. UXO source emission measurements are being made to estimate the chemical flux from a limited set of ordnance items. Phase partitioning analysis has been completed to show what the expected concentrations of chemical analytes would be fi-om total concentrations measured in the soil. The soil moisture content in the dry region has been shown to be critical in the attenuation of soil gas concentrations by increased sorption to soil particles. Numerical simulation tools have been adapted to include surface boundary conditions such as solar radiation, surface boundary layer (which is a function of wind speed), precipitation and evaporation, and plant cover/root density to allow transport modeling and evaluate long term processes. Results of this work will provide performance targets for sensor developers and support operational decisions regarding field deployments.

  2. Dynamic (G2) Model Design Document, 24590-WTP-MDD-PR-01-002, Rev. 12

    SciTech Connect

    Deng, Yueying; Kruger, Albert A.

    2013-12-16

    The Hanford Tank Waste Treatment and Immobilization Plant (WTP) Statement of Work (Department of Energy Contract DE-AC27-01RV14136, Section C) requires the contractor to develop and use process models for flowsheet analyses and pre-operational planning assessments. The Dynamic (G2) Flowsheet is a discrete-time process model that enables the project to evaluate impacts to throughput from eventdriven activities such as pumping, sampling, storage, recycle, separation, and chemical reactions. The model is developed by the Process Engineering (PE) department, and is based on the Flowsheet Bases, Assumptions, and Requirements Document (24590-WTP-RPT-PT-02-005), commonly called the BARD. The terminologies of Dynamic (G2) Flowsheet and Dynamic (G2) Model are interchangeable in this document. The foundation of this model is a dynamic material balance governed by prescribed initial conditions, boundary conditions, and operating logic. The dynamic material balance is achieved by tracking the storage and material flows within the plant as time increments. The initial conditions include a feed vector that represents the waste compositions and delivery sequence of the Tank Farm batches, and volumes and concentrations of solutions in process equipment before startup. The boundary conditions are the physical limits of the flowsheet design, such as piping, volumes, flowrates, operation efficiencies, and physical and chemical environments that impact separations, phase equilibriums, and reaction extents. The operating logic represents the rules and strategies of running the plant.

  3. Radiation Chemistry of Advanced TALSPEAK Flowsheet

    SciTech Connect

    Mincher, Bruce; Peterman, Dean; Mcdowell, Rocklan; Olson, Lonnie; Lumetta, Gregg J.

    2013-08-28

    This report summarizes the results of initial experiments designed to understand the radiation chemistry of an Advanced TALSPEAK process for separating trivalent lanthanides form the actinides. Biphasic aerated samples were irradiated and then analyzed for post-irradiation constituent concentrations and solvent extraction distribution ratios. The effects of irradiation on the TALSPEAK and Advanced TALSPEAK solvents were similar, with very little degradation of the organic phase extractant. Decomposition products were detected, with a major product in common for both solvents. This product may be responsible for the slight increase in distribution ratios for Eu and Am with absorbed dose, however; separation factors were not greatly affected.

  4. Separation of parent homopolymers from polystyrene and poly(ethylene oxide) based block copolymers by liquid chromatography under limiting conditions of desorption-3. Study of barrier efficiency according to block copolymers' chemical composition.

    PubMed

    Rollet, Marion; Pelletier, Bérengère; Berek, Dušan; Maria, Sébastien; Phan, Trang N T; Gigmes, Didier

    2016-09-01

    Liquid Chromatography under Limiting Conditions of Desorption (LC LCD) is a powerful separation tool for multicomponent polymer systems. This technique is based on a barrier effect of an appropriate solvent, which is injected in front of the sample, and which decelerates the elution of selected macromolecules. In this study, the barrier effects have been evaluated for triblock copolymers polystyrene-b-poly(ethylene oxide)-b-polystyrene (PS-b-PEO-b-PS) according to the content of polystyrene (wt% PS) and PEO-block molar mass. PS-b-PEO-b-PS samples were prepared by Atom Transfer Radical Polymerization (ATRP). The presence of respective parent homopolymers was investigated by applying optimized LC LCD conditions. It was found that the barrier composition largely affects the efficiency of separation and it ought to be adjusted for particular composition range of block copolymers. PMID:27495367

  5. SLUDGE BATCH 6/TANK 40 SIMULANT CHEMICAL PROCESS CELL SIMULATIONS

    SciTech Connect

    Koopman, David

    2010-04-28

    Phase III simulant flowsheet testing was completed using the latest composition estimates for SB6/Tank 40 feed to DWPF. The goals of the testing were to determine reasonable operating conditions and assumptions for the startup of SB6 processing in the DWPF. Testing covered the region from 102-159% of the current DWPF stoichiometric acid equation. Nitrite ion concentration was reduced to 90 mg/kg in the SRAT product of the lowest acid run. The 159% acid run reached 60% of the DWPF Sludge Receipt and Adjustment Tank (SRAT) limit of 0.65 lb H2/hr, and then sporadically exceeded the DWPF Slurry Mix Evaporator (SME) limit of 0.223 lb H2/hr. Hydrogen generation rates peaked at 112% of the SME limit, but higher than targeted wt% total solids levels may have been partially responsible for rates seen. A stoichiometric factor of 120% met both objectives. A processing window for SB6 exists from 102% to something close to 159% based on the simulant results. An initial recommendation for SB6 processing is at 115-120% of the current DWPF stoichiometric acid equation. The addition of simulated Actinide Removal Process (ARP) and Modular Caustic Side Solvent Extraction Unit (MCU) streams to the SRAT cycle had no apparent impact on the preferred stoichiometric factor. Hydrogen generation occurred continuously after acid addition in three of the four tests. The three runs at 120%, 118.4% with ARP/MCU, and 159% stoichiometry were all still producing around 0.1 lb hydrogen/hr at DWPF scale after 36 hours of boiling in the SRAT. The 120% acid run reached 23% of the SRAT limit and 37% of the SME limit. Conversely, nitrous oxide generation was subdued compared to previous sludge batches, staying below 29 lb/hr in all four tests or about a fourth as much as in comparable SB4 testing. Two processing issues, identified during SB6 Phase II flowsheet testing and qualification simulant testing, were monitored during Phase III. Mercury material balance closure was impacted by acid stoichiometry

  6. Chemical Safety Vulnerability Working Group report. Volume 1

    SciTech Connect

    Not Available

    1994-09-01

    The Chemical Safety Vulnerability (CSV) Working Group was established to identify adverse conditions involving hazardous chemicals at DOE facilities that might result in fires or explosions, release of hazardous chemicals to the environment, or exposure of workers or the public to chemicals. A CSV Review was conducted in 148 facilities at 29 sites. Eight generic vulnerabilities were documented related to: abandoned chemicals and chemical residuals; past chemical spills and ground releases; characterization of legacy chemicals and wastes; disposition of legacy chemicals; storage facilities and conditions; condition of facilities and support systems; unanalyzed and unaddressed hazards; and inventory control and tracking. Weaknesses in five programmatic areas were also identified related to: management commitment and planning; chemical safety management programs; aging facilities that continue to operate; nonoperating facilities awaiting deactivation; and resource allocations. Volume 1 contains the Executive summary; Introduction; Summary of vulnerabilities; Management systems weaknesses; Commendable practices; Summary of management response plan; Conclusions; and a Glossary of chemical terms.

  7. Chemically Induced Conditional Rescue of the Reduced Epidermal Fluorescence8 Mutant of Arabidopsis Reveals Rapid Restoration of Growth and Selective Turnover of Secondary Metabolite Pools1[C][OPEN

    PubMed Central

    Kim, Jeong Im; Ciesielski, Peter N.; Donohoe, Bryon S.; Chapple, Clint; Li, Xu

    2014-01-01

    The phenylpropanoid pathway is responsible for the biosynthesis of diverse and important secondary metabolites including lignin and flavonoids. The reduced epidermal fluorescence8 (ref8) mutant of Arabidopsis (Arabidopsis thaliana), which is defective in a lignin biosynthetic enzyme p-coumaroyl shikimate 3′-hydroxylase (C3′H), exhibits severe dwarfism and sterility. To better understand the impact of perturbation of phenylpropanoid metabolism on plant growth, we generated a chemically inducible C3′H expression construct and transformed it into the ref8 mutant. Application of dexamethasone to these plants greatly alleviates the dwarfism and sterility and substantially reverses the biochemical phenotypes of ref8 plants, including the reduction of lignin content and hyperaccumulation of flavonoids and p-coumarate esters. Induction of C3′H expression at different developmental stages has distinct impacts on plant growth. Although early induction effectively restored the elongation of primary inflorescence stem, application to 7-week-old plants enabled them to produce new rosette inflorescence stems. Examination of hypocotyls of these plants revealed normal vasculature in the newly formed secondary xylem, presumably restoring water transport in the mutant. The ref8 mutant accumulates higher levels of salicylic acid than the wild type, but depletion of this compound in ref8 did not relieve the mutant’s growth defects, suggesting that the hyperaccumulation of salicylic acid is unlikely to be responsible for dwarfism in this mutant. PMID:24381065

  8. Hyperbaric conditions.

    PubMed

    Doolette, David J; Mitchell, Simon J

    2011-01-01

    Exposure to elevated ambient pressure (hyperbaric conditions) occurs most commonly in underwater diving, during which respired gas density and partial pressures, work of breathing, and physiological dead space are all increased. There is a tendency toward hypercapnia during diving, with several potential causes. Most importantly, there may be reduced responsiveness of the respiratory controller to rising arterial CO₂, leading to hypoventilation and CO₂ retention. Contributory factors may include elevated arterial PO₂, inert gas narcosis and an innate (but variable) tendency of the respiratory controller to sacrifice tight control of arterial CO₂ when work of breathing increases. Oxygen is usually breathed at elevated partial pressure under hyperbaric conditions. Oxygen breathing at modest hyperbaric pressure is used therapeutically in hyperbaric chambers to increase arterial carriage of oxygen and diffusion into tissues. However, to avoid cerebral and pulmonary oxygen toxicity during underwater diving, both the magnitude and duration of oxygen exposure must be managed. Therefore, most underwater diving is conducted breathing mixtures of oxygen and inert gases such as nitrogen or helium, often simply air. At hyperbaric pressure, tissues equilibrate over time with high inspired inert gas partial pressure. Subsequent decompression may reduce ambient pressure below the sum of tissue gas partial pressures (supersaturation) which can result in tissue gas bubble formation and potential injury (decompression sickness). Risk of decompression sickness is minimized by scheduling time at depth and decompression rate to limit tissue supersaturation or size and profusion of bubbles in accord with models of tissue gas kinetics and bubble formation and growth. PMID:23737169

  9. Effect of light conditions on the resistance of current-year Fagus Crenata seedlings against fungal pathogens causing damping-off in a natural beech forest: fungus isolation and histological and chemical resistance.

    PubMed

    Ichihara, Yu; Yamaji, Keiko

    2009-09-01

    Forest gap dynamics affects light intensity on the forest floor, which in turn may influence defense and survival of tree seedlings. Current-year Fagus crenata seedlings show high mortality under the canopy caused by damping-off. In contrast, they survive pathogen attacks in gaps. However, defense mechanisms against damping-off have not been fully understood. In order to determine the resistance factors that affect mortality in current-year seedlings, we compared seedling survival and chemical and histological characteristics of the hypocotyls of seedlings from closed-stand and forest-edge plots. Damping-off occurred in the current-year seedlings mainly from the end of June to July; survival rate of the seedlings was higher in the forest-edge plot than in the closed-stand plot. By performing an inoculation test on the seedling hypocotyls, we identified Colletotrichum dematium and Cylindrocarpon sp. as the causative pathogens under low illumination only. In the beginning of July, only seedling hypocotyls from the forest-edge plot exhibited periderm formation. From mid-June to July, seedling hypocotyls from the forest-edge plot accumulated approximately twice the amount of total phenols as those accumulated by seedling hypocotyls from the closed-stand plot. The ethyl acetate phase of methanol extracts of hypocotyls showed antifungal activity. We conclude that seedlings from the forest-edge plot may resist pathogenic attack via periderm formation and increased phenol synthesis. Plant defense mechanisms that are controlled by light intensity may be important for promoting seedling regeneration in forest gap dynamics. PMID:19774414

  10. Safety in the Chemical Laboratory: Tested Disposal Methods for Chemical Wastes from Academic Laboratories.

    ERIC Educational Resources Information Center

    Armour, M. A.; And Others

    1985-01-01

    Describes procedures for disposing of dichromate cleaning solution, picric acid, organic azides, oxalic acid, chemical spills, and hydroperoxides in ethers and alkenes. These methods have been tested under laboratory conditions and are specific for individual chemicals rather than for groups of chemicals. (JN)

  11. Operant Conditioning

    PubMed Central

    Staddon, J. E. R.; Cerutti, D. T.

    2005-01-01

    Operant behavior is behavior “controlled” by its consequences. In practice, operant conditioning is the study of reversible behavior maintained by reinforcement schedules. We review empirical studies and theoretical approaches to two large classes of operant behavior: interval timing and choice. We discuss cognitive versus behavioral approaches to timing, the “gap” experiment and its implications, proportional timing and Weber's law, temporal dynamics and linear waiting, and the problem of simple chain-interval schedules. We review the long history of research on operant choice: the matching law, its extensions and problems, concurrent chain schedules, and self-control. We point out how linear waiting may be involved in timing, choice, and reinforcement schedules generally. There are prospects for a unified approach to all these areas. PMID:12415075

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

    SciTech Connect

    PHELAN, JAMES M.

    2002-05-01

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

  13. Chemical Engineering in Space

    NASA Technical Reports Server (NTRS)

    Lobmeyer, Dennis A.; Meneghelli, Barry; Steinrock, Todd (Technical Monitor)

    2001-01-01

    The aerospace industry has long been perceived as the domain of both physicists and mechanical engineers. This perception has endured even though the primary method of providing the thrust necessary to launch a rocket into space is chemical in nature. The chemical engineering and chemistry personnel behind the systems that provide access to space have labored in the shadows of the physicists and mechanical engineers. As exploration into the cosmos moves farther away from Earth, there is a very distinct need for new chemical processes to help provide the means for advanced space exploration. The state of the art in launch systems uses chemical propulsion systems, primarily liquid hydrogen and liquid oxygen, to provide the energy necessary to achieve orbit. As we move away from Earth, there are additional options for propulsion. Unfortunately, few of these options can compare to the speed or ease of use provided by the chemical propulsion agents. It is with great care and significant cost that gaseous compounds such as hydrogen and oxygen are liquefied and become dense enough to use for rocket fuel. These low-temperature liquids fall within a specialty area known as cryogenics. Cryogenics, the science and art of producing cold operating conditions for use on Earth, in orbit, or on some other nonterrestrial body, has become increasingly important to our ability to travel within our solar system. The production of cryogenic fuels and the long-term storage of these fluids are necessary for travel. As our explorations move farther away from Earth, we need to address how to produce the necessary fuels to make a round-trip. The cost and the size of these expeditions are extreme at best. If we take everything necessary for our survival for the round-trip, we invalidate any chance of travel in the near future. As with the early explorers on Earth, we need to harvest much of our energy and our life support from the celestial bodies. The in situ production of these energy

  14. ENGINEERING BULLETIN: CHEMICAL OXIDATION TREATMENT

    EPA Science Inventory

    Oxidation destroys hazardous contaminants by chemically converting them to nonhazardous or less toxic compounds that are ideally more stable, less mobile, and/or inert. However, under some conditions, other hazardous compounds may be formed. The oxidizing agents most commonly use...

  15. How Cells Endure Extreme Conditions

    SciTech Connect

    2009-01-01

    One of natures most gripping feats of survival is now better understood. For the first time, Berkeley Lab scientists observed the chemical changes in individual cells that enable them to survive in conditions that should kill them. http://newscenter.lbl.gov/feature-stories/2009/07/07/cells-endure-extremes/

  16. 49 CFR 173.168 - Chemical oxygen generators.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 2 2010-10-01 2010-10-01 false Chemical oxygen generators. 173.168 Section 173... Class 7 § 173.168 Chemical oxygen generators. An oxygen generator, chemical (defined in § 171.8 of this subchapter) may be transported only under the following conditions: (a) Approval. A chemical oxygen...

  17. 49 CFR 173.168 - Chemical oxygen generators.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 2 2013-10-01 2013-10-01 false Chemical oxygen generators. 173.168 Section 173... Class 7 § 173.168 Chemical oxygen generators. An oxygen generator, chemical (defined in § 171.8 of this subchapter) may be transported only under the following conditions: (a) Approval. A chemical oxygen...

  18. 49 CFR 173.168 - Chemical oxygen generators.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 2 2012-10-01 2012-10-01 false Chemical oxygen generators. 173.168 Section 173... Class 7 § 173.168 Chemical oxygen generators. An oxygen generator, chemical (defined in § 171.8 of this subchapter) may be transported only under the following conditions: (a) Approval. A chemical oxygen...

  19. 49 CFR 173.168 - Chemical oxygen generators.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 2 2014-10-01 2014-10-01 false Chemical oxygen generators. 173.168 Section 173... Class 7 § 173.168 Chemical oxygen generators. An oxygen generator, chemical (defined in § 171.8 of this subchapter) may be transported only under the following conditions: (a) Approval. A chemical oxygen...

  20. 49 CFR 173.168 - Chemical oxygen generators.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 2 2011-10-01 2011-10-01 false Chemical oxygen generators. 173.168 Section 173... Class 7 § 173.168 Chemical oxygen generators. An oxygen generator, chemical (defined in § 171.8 of this subchapter) may be transported only under the following conditions: (a) Approval. A chemical oxygen...

  1. Chemical Ecology: Chemical Communication in Nature.

    ERIC Educational Resources Information Center

    Wood, William F.

    1983-01-01

    Substances that deliver chemical messages between same/different species are called semiochemicals. Surveyed are three types of semiochemicals (pheromones, allomones, and kairomones), types of organisms involved, and specific chemicals used to carry the various kinds of messages. (JN)

  2. Identifying chemicals that are planetary boundary threats.

    PubMed

    MacLeod, Matthew; Breitholtz, Magnus; Cousins, Ian T; de Wit, Cynthia A; Persson, Linn M; Rudén, Christina; McLachlan, Michael S

    2014-10-01

    Rockström et al. proposed a set of planetary boundaries that delimit a "safe operating space for humanity". Many of the planetary boundaries that have so far been identified are determined by chemical agents. Other chemical pollution-related planetary boundaries likely exist, but are currently unknown. A chemical poses an unknown planetary boundary threat if it simultaneously fulfills three conditions: (1) it has an unknown disruptive effect on a vital Earth system process; (2) the disruptive effect is not discovered until it is a problem at the global scale, and (3) the effect is not readily reversible. In this paper, we outline scenarios in which chemicals could fulfill each of the three conditions, then use the scenarios as the basis to define chemical profiles that fit each scenario. The chemical profiles are defined in terms of the nature of the effect of the chemical and the nature of exposure of the environment to the chemical. Prioritization of chemicals in commerce against some of the profiles appears feasible, but there are considerable uncertainties and scientific challenges that must be addressed. Most challenging is prioritizing chemicals for their potential to have a currently unknown effect on a vital Earth system process. We conclude that the most effective strategy currently available to identify chemicals that are planetary boundary threats is prioritization against profiles defined in terms of environmental exposure combined with monitoring and study of the biogeochemical processes that underlie vital Earth system processes to identify currently unknown disruptive effects. PMID:25181298

  3. The Chemical Engineer in the Chemical Industry.

    ERIC Educational Resources Information Center

    Zabicky, Jacob

    1986-01-01

    Describes a course for third- or fourth-year chemical engineering students designed to acquaint them with the chemical industry. The course deals with productivity, characteristics of the chemical industry, sources of information, industrial intelligence, research and development, patent law, technology transfer, and quality control. (TW)

  4. Microfluidic chemical reaction circuits

    DOEpatents

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

    2012-06-26

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

  5. CHEMICAL SAFETY ALERTS-

    EPA Science Inventory

    Chemical Safety Alerts are short publications which explain specific hazards that have become evident through chemical accident investigation efforts. EPA has produced over a dozen Alerts to date. This year's Alert: Managing Chemical Reactivity Hazards

  6. CHEMICALS IN PROGRESS BULLETIN

    EPA Science Inventory

    Chemicals in Progress Bulletin is a quarterly newsletter which highlights regulatory and program activities of the Office of Pollution Prevention and Toxics. Regular features and news items include the existing chemicals program, new chemicals program, pollution prevention activi...

  7. INFLUENCE OF MACROMOLECULES ON CHEMICAL TRANSPORT

    EPA Science Inventory

    Macromolecules in the pore fluid influence the mobility of hydrophobic compounds through soils. his study evaluated the significance of macromolecules in facilitating chemical transport under laboratory conditions. Partition coefficients between 14C-labeled hexachlorobenzene and ...

  8. Testing and comparison of seventeen decontamination chemicals

    SciTech Connect

    Demmer, R.L.

    1996-09-01

    This report details the testing and evaluation of seventeen decontamination chemicals. Tests were conducted with SIMCON (simulated contamination) coupons under controlled conditions to compare cleaning effectiveness, overall corrosion potential for plant equipment, interim waste generation and final waste generation.

  9. Mechanisms of multiple chemical sensitivity.

    PubMed

    Winder, Chris

    2002-03-10

    Sensitivity to chemicals is a toxicological concept, contained in the dose-response relationship. Sensitivity also includes the concept of hypersensitivity, although controversy surrounds the nature of effects from very low exposures. The term multiple chemical sensitivity has been used to describe individuals with a debilitating, multi-organ sensitivity following chemical exposures. Many aspects of this condition extend the nature of sensitivity to low levels of exposure to chemicals, and is a designation with medical, immunological, neuropsychological and toxicological perspectives. The basis of MCS is still to be identified, although a large number of hypersensitivity, immunological, psychological, neurological and toxicological mechanisms have been suggested, including: allergy; autosuggestion; cacosomia; conditioned response; immunological; impairment of biochemical pathways involved in energy production; impairment of neurochemical pathways; illness belief system; limbic kindling; olfactory threshold sensitivity; panic disorder; psychosomatic condition; malingering; neurogenic inflammation; overload of biotransformation pathways (also linked with free radical production); psychological or psychiatric illness; airway reactivity; sensitisation of the neurological system; time dependent sensitisation, toxicant induced loss of tolerance. Most of these theories tend to break down into concepts involving: (1) disruption in immunological/allergy processes; (2) alteration in nervous system function; (3) changes in biochemical or biotransformation capacity; (4) changes in psychological/neurobehavioural function. Research into the possible mechanisms of MCS is far from complete. However, a number of promising avenues of investigation indicate that the possibility of alteration of the sensitivity of nervous system cells (neurogenic inflammation, limbic kindling, cacosomia, neurogenic switching) are a possible mechanism for MCS. PMID:11869820

  10. Chemical Management System

    Energy Science and Technology Software Center (ESTSC)

    1998-10-30

    CMS provides an inventory of all chemicals on order or being held in the laboratory, to provide a specific location for all chemical containers, to ensure that health and safety regulatory codes are being upheld, and to provide PNNL staff with hazardous chemical information to better manage their inventories. CMS is comprised of five major modules: 1) chemical purchasing, 2) chemical inventory, 3) chemical names, properties, and hazard groups, 4) reporting, and 5) system administration.

  11. Nature's chemicals and synthetic chemicals: Comparative toxicology

    SciTech Connect

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

    1990-10-01

    The toxicology of synthetic chemicals is compared to that of natural chemicals, which represent the vast bulk of the chemicals to which humans are exposed. It is argued that animals have a broad array of inducible general defenses to combat the changing array of toxic chemicals in plant food (nature's pesticides) and that these defenses are effective against both natural and synthetic toxins. Synthetic toxins such as dioxin are compared to natural chemicals, such as indole carbinol (in broccoli) and ethanol. Trade-offs between synthetic and natural pesticides are discussed. The finding that in high-dose tests, a high proportion of both natural and synthetic chemicals are carcinogens, mutagens, teratogens, and clastogens (30-50{percent} for each group) undermines current regulatory efforts to protect public health from synthetic chemicals based on these tests.

  12. Minimal conditions for protocell stationary growth.

    PubMed

    Bigan, Erwan; Steyaert, Jean-Marc; Douady, Stéphane

    2015-01-01

    We show that self-replication of a chemical system encapsulated within a membrane growing from within is possible without any explicit feature such as autocatalysis or metabolic closure, and without the need for their emergence through complexity. We use a protocell model relying upon random conservative chemical reaction networks with arbitrary stoichiometry, and we investigate the protocell's capability for self-replication, for various numbers of reactions in the network. We elucidate the underlying mechanisms in terms of simple minimal conditions pertaining only to the topology of the embedded chemical reaction network. A necessary condition is that each moiety must be fed, and a sufficient condition is that each siphon is fed. Although these minimal conditions are purely topological, by further endowing conservative chemical reaction networks with thermodynamically consistent kinetics, we show that the growth rate tends to increase on increasing the Gibbs energy per unit molecular weight of the nutrient and on decreasing that of the membrane precursor. PMID:25951201

  13. Chemical Industry Corrosion Management

    SciTech Connect

    2003-02-01

    Improved Corrosion Management Could Provide Significant Cost and Energy Savings for the Chemical Industry. In the chemical industry, corrosion is often responsible for significant shutdown and maintenance costs.

  14. Review of Catalytic Hydrogen Generation in the DWPF Chemical Processing Cell, Part II

    SciTech Connect

    Koopman, David C.; Lambert, Daniel P.; Baich, Mark A.

    2005-08-01

    The Savannah River National Laboratory is in the process of investigating factors suspected of impacting catalytic hydrogen generation in the Defense Waste Processing Facility, DWPF, Chemical Process Cell, CPC. Noble metal catalyzed hydrogen generation in simulation work constrains the allowable acid addition operating window in DWPF. This constraint potentially impacts washing strategies during sludge batch preparation. It can also influence decisions related to the addition of secondary waste streams to a sludge batch. Catalytic hydrogen generation data from 2002-2005 were reviewed. The data came from process simulations of the DWPF Sludge Receipt and Adjustment Tank, SRAT, and Slurry Mix Evaporator, SME. Most of the data was from the development work for the Sludge Batch 3 process flowsheet. This included simulant and radioactive waste testing. Preliminary Sludge Batch 4 data were also reviewed. A statistical analysis of SB3 simulant hydrogen generation data was performed. One factor considered in the statistical analysis was excess acid. Excess acid was determined experimentally as the acid added beyond that required to achieve satisfactory nitrite destruction.

  15. Cues of maternal condition influence offspring selfishness.

    PubMed

    Wong, Janine W Y; Lucas, Christophe; Kölliker, Mathias

    2014-01-01

    The evolution of parent-offspring communication was mostly studied from the perspective of parents responding to begging signals conveying information about offspring condition. Parents should respond to begging because of the differential fitness returns obtained from their investment in offspring that differ in condition. For analogous reasons, offspring should adjust their behavior to cues/signals of parental condition: parents that differ in condition pay differential costs of care and, hence, should provide different amounts of food. In this study, we experimentally tested in the European earwig (Forficula auricularia) if cues of maternal condition affect offspring behavior in terms of sibling cannibalism. We experimentally manipulated female condition by providing them with different amounts of food, kept nymph condition constant, allowed for nymph exposure to chemical maternal cues over extended time, quantified nymph survival (deaths being due to cannibalism) and extracted and analyzed the females' cuticular hydrocarbons (CHC). Nymph survival was significantly affected by chemical cues of maternal condition, and this effect depended on the timing of breeding. Cues of poor maternal condition enhanced nymph survival in early broods, but reduced nymph survival in late broods, and vice versa for cues of good condition. Furthermore, female condition affected the quantitative composition of their CHC profile which in turn predicted nymph survival patterns. Thus, earwig offspring are sensitive to chemical cues of maternal condition and nymphs from early and late broods show opposite reactions to the same chemical cues. Together with former evidence on maternal sensitivities to condition-dependent nymph chemical cues, our study shows context-dependent reciprocal information exchange about condition between earwig mothers and their offspring, potentially mediated by cuticular hydrocarbons. PMID:24498046

  16. Modeling of turbulent chemical reaction

    NASA Technical Reports Server (NTRS)

    Chen, J.-Y.

    1995-01-01

    Viewgraphs are presented on modeling turbulent reacting flows, regimes of turbulent combustion, regimes of premixed and regimes of non-premixed turbulent combustion, chemical closure models, flamelet model, conditional moment closure (CMC), NO(x) emissions from turbulent H2 jet flames, probability density function (PDF), departures from chemical equilibrium, mixing models for PDF methods, comparison of predicted and measured H2O mass fractions in turbulent nonpremixed jet flames, experimental evidence of preferential diffusion in turbulent jet flames, and computation of turbulent reacting flows.

  17. Chemical kinetics on extrasolar planets.

    PubMed

    Moses, Julianne I

    2014-04-28

    Chemical kinetics plays an important role in controlling the atmospheric composition of all planetary atmospheres, including those of extrasolar planets. For the hottest exoplanets, the composition can closely follow thermochemical-equilibrium predictions, at least in the visible and infrared photosphere at dayside (eclipse) conditions. However, for atmospheric temperatures approximately <2000K, and in the uppermost atmosphere at any temperature, chemical kinetics matters. The two key mechanisms by which kinetic processes drive an exoplanet atmosphere out of equilibrium are photochemistry and transport-induced quenching. I review these disequilibrium processes in detail, discuss observational consequences and examine some of the current evidence for kinetic processes on extrasolar planets. PMID:24664912

  18. New push for chemical weapons

    SciTech Connect

    Weickhardt, G.G.; Finberg, J.M.

    1986-11-01

    The Reagan Administration's desire to produce new chemical weapons has stirred controversy on both sides of the Atlantic. In Europe, seven NATO members recently declared that they will never permit shipments of chemical weapons to US forces on their territory, and six others have placed conditions on such shipments. In the US, the Senate voted narrowly in August to authorize production of binary nerve gas to begin on October 1, and a week later the House voted just as narrowly to delay production. The controversy will not end soon, regardless of any compromise reached by the House and Senate, because it touches on US relations with its allies, the Soviet Union, and international negotiations for a global ban on chemical weapons. Negotiations for such a ban have been conducted by the 40-nation Conference on Disarmament in Geneva since 1968. At the heart of the issue lies the notion of chemical deterrence, the disputed theory that nations need chemical weapons to deter their use by other nations. Ways in which chemical deterrence differs from nuclear deterrence are discussed.

  19. [Chemical food contaminants].

    PubMed

    Schrenk, D

    2004-09-01

    Chemical food contaminants are substances which are neither present naturally in the usual raw material used for food production nor are added during the regular production process. Examples are environmental pollutants or contaminants derived from agricultural production of crops or livestock or from inadequate manufacturing of the food product itself. More difficult is the classification of those compounds formed during regular manufacturing such as products of thermal processes including flavoring substances. In these cases, it is common practice to call those compounds contaminants which are known for their adverse effects such as acrylamide, whereas constituents which add to the food-specific flavor such as Maillard products formed during roasting, baking etc. are not termed contaminants. From a toxicological viewpoint this distinction is not always clear-cut. Important groups of chemical contaminants are metals such as mercury or lead, persistent organic pollutants such as polychlorinated biphenyls and related pollutants, which are regularly found in certain types of food originating from background levels of these compounds in our environment. Furthermore, natural toxins form microorganisms or plants, and compounds formed during thermal treatment of food are of major interest. In general, a scientific risk assessment has to be carried out for any known contaminant. This comprises an exposure analysis and a toxicological and epidemiological assessment. On these grounds, regulatory and/or technological measures can often improve the situation. Major conditions for a scientific risk assessment and a successful implementation of regulations are highly developed food quality control, food toxicology and nutritional epidemiology. PMID:15378171

  20. Chemical simulation of greywater.

    PubMed

    Abed, Suhail Najem; Scholz, Miklas

    2016-01-01

    Sustainable water resources management attracts considerable attention in today's world. Recycling and reuse of both wastewater and greywater are becoming more attractive. The strategy is to protect ecosystem services by balancing the withdrawal of water and the disposal of wastewater. In the present study, a timely and novel synthetic gr