WorldWideScience

Sample records for critical solvents optimization

  1. What makes critical-solvent processes work

    Energy Technology Data Exchange (ETDEWEB)

    Brule, M.R.; Corbett, R.W.

    1984-06-01

    Critical-solvent processing (sometimes called supercritical-gas extraction) is an ongoing technology based on phase-equilibrium phenomena in the critical region. Many new practical applications of critical-solvent processing are being conceived and implemented in the food, drug and chemical industries. The advantages afforded by critical-solvent processing in performing difficult separations such as caffeine from coffee, nicotine from tobacco, chemotherapeutic drugs from plants, and chemical feedstocks from petroleum and synfuels residua have been realized just in the last decade or so.

  2. Solvent-dependent critical properties of polymer adsorption

    Science.gov (United States)

    Plascak, João A.; Martins, Paulo H. L.; Bachmann, Michael

    2017-05-01

    Advanced chain-growth computer simulation methodologies have been employed for a systematic statistical analysis of the critical behavior of a polymer adsorbing at a substrate. We use finite-size scaling techniques to investigate the solvent-quality dependence of critical exponents, critical temperature, and the structure of the phase diagram. Our study covers all solvent effects from the limit of super-self-avoiding walks, characterized by effective monomer-monomer repulsion, to poor solvent conditions that enable the formation of compact polymer structures. The results significantly benefit from taking into account corrections to scaling.

  3. Caustic-Side Solvent Extraction: Chemical and Physical Properties of the Optimized Solvent

    Energy Technology Data Exchange (ETDEWEB)

    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. Liquid bridging of cylindrical colloids in near-critical solvents

    Science.gov (United States)

    Labbé-Laurent, M.; Law, A. D.; Dietrich, S.

    2017-09-01

    Within mean field theory, we investigate the bridging transition between a pair of parallel cylindrical colloids immersed in a binary liquid mixture as a solvent that is close to its critical consolute point Tc. We determine the universal scaling functions of the effective potential and of the force between the colloids. For a solvent that is at the critical concentration and close to Tc, we find that the critical Casimir force is the dominant interaction at close separations. This agrees very well with the corresponding Derjaguin approximation for the effective interaction between the two cylinders, while capillary forces originating from the extension of the liquid bridge turn out to be more important at large separations. In addition, we are able to infer from the wetting characteristics of the individual colloids the first-order transition of the liquid bridge connecting two colloidal particles to the ruptured state. While specific to cylindrical colloids, the results presented here also provide an outline for identifying critical Casimir forces acting on bridged colloidal particles as such and for analyzing the bridging transition between them.

  5. Solvent

    OpenAIRE

    Hamida Y. Mostafa; Ebaa A. El-Shamy; Amal S. Farag; Nadia G. Kandile

    2013-01-01

    Neat ethylacetoacetate (EAA) and its mixtures with a co-solvent and an anti-solvent have been studied for refining of heavy wax distillate fraction to produce substantially non-carcinogenic base oil. The co-solvent and anti-solvent used are dipropylene glycol (DPG) and ethylene glycol (EG) respectively. The solubility characteristics of the main solvent and its mixed solvent systems were studied. Selection of the optimum solvent mixture and extraction variables has been studied. The effect of...

  6. Solvent

    Directory of Open Access Journals (Sweden)

    Hamida Y. Mostafa

    2013-12-01

    Full Text Available Neat ethylacetoacetate (EAA and its mixtures with a co-solvent and an anti-solvent have been studied for refining of heavy wax distillate fraction to produce substantially non-carcinogenic base oil. The co-solvent and anti-solvent used are dipropylene glycol (DPG and ethylene glycol (EG respectively. The solubility characteristics of the main solvent and its mixed solvent systems were studied. Selection of the optimum solvent mixture and extraction variables has been studied. The effect of co-solvent and anti-solvent addition on the carcinogenic potential and raffinate quality has been determined under clearly comparable conditions.

  7. Polymer models with optimal good-solvent behavior

    Science.gov (United States)

    D'Adamo, Giuseppe; Pelissetto, Andrea

    2017-11-01

    We consider three different continuum polymer models, which all depend on a tunable parameter r that determines the strength of the excluded-volume interactions. In the first model, chains are obtained by concatenating hard spherocylinders of height b and diameter rb (we call them thick self-avoiding chains). The other two models are generalizations of the tangent hard-sphere and of the Kremer-Grest models. We show that for a specific value r* , all models show optimal behavior: asymptotic long-chain behavior is observed for relatively short chains. For r properties and for dynamical studies. Such a model also provides a coarse-grained description of double-stranded DNA, so that we can use our results to discuss under which conditions DNA can be considered as a model good-solvent polymer.

  8. Optimal (Solvent) Mixture Design through a Decomposition Based CAMD methodology

    DEFF Research Database (Denmark)

    Achenie, L.; Karunanithi, Arunprakash T.; Gani, Rafiqul

    2004-01-01

    Computer Aided Molecular/Mixture design (CAMD) is one of the most promising techniques for solvent design and selection. A decomposition based CAMD methodology has been formulated where the mixture design problem is solved as a series of molecular and mixture design sub-problems. This approach is...... is able to overcome most of the difficulties associated with the solution of mixture design problems. The new methodology has been illustrated with the help of a case study involving the design of solvent-anti solvent binary mixtures for crystallization of Ibuprofen....

  9. Process optimization for inkjet printing of triisopropylsilylethynyl pentacene with single-solvent solutions

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xianghua, E-mail: xhwang@hfut.edu.cn [Key Lab of Special Display Technology, Ministry of Education, National Engineering Lab of Special Display Technology, National Key Lab of Advanced Display Technology, Academy of Opto-Electronic Technology, Hefei University of Technology, Hefei 230009 (China); Yuan, Miao [Key Lab of Special Display Technology, Ministry of Education, National Engineering Lab of Special Display Technology, National Key Lab of Advanced Display Technology, Academy of Opto-Electronic Technology, Hefei University of Technology, Hefei 230009 (China); School of Electronic Science & Applied Physics, Hefei University of Technology, Hefei 230009 (China); Xiong, Xianfeng; Chen, Mengjie [Key Lab of Special Display Technology, Ministry of Education, National Engineering Lab of Special Display Technology, National Key Lab of Advanced Display Technology, Academy of Opto-Electronic Technology, Hefei University of Technology, Hefei 230009 (China); Qin, Mengzhi [Key Lab of Special Display Technology, Ministry of Education, National Engineering Lab of Special Display Technology, National Key Lab of Advanced Display Technology, Academy of Opto-Electronic Technology, Hefei University of Technology, Hefei 230009 (China); School of Electronic Science & Applied Physics, Hefei University of Technology, Hefei 230009 (China); Qiu, Longzhen; Lu, Hongbo; Zhang, Guobing; Lv, Guoqiang [Key Lab of Special Display Technology, Ministry of Education, National Engineering Lab of Special Display Technology, National Key Lab of Advanced Display Technology, Academy of Opto-Electronic Technology, Hefei University of Technology, Hefei 230009 (China); Choi, Anthony H.W. [Department of Electrical and Electronic Engineering, The University of Hong Kong, Hong Kong (China)

    2015-03-02

    Inkjet printing of 6,13-bis(triisopropylsilylethynyl) pentacene (TIPS-PEN), a small molecule organic semiconductor, is performed on two types of substrates. Hydrophilic SiO{sub 2} substrates prepared by a combination of surface treatments lead to either a smaller size or a coffee-ring profile of the single-drop film. A hydrophobic surface with dominant dispersive component of surface energy such as that of a spin-coated poly(4-vinylphenol) film favors profile formation with uniform thickness of the printed semiconductor owing to the strong dispersion force between the semiconductor molecules and the hydrophobic surface of the substrate. With a hydrophobic dielectric as the substrate and via a properly selected solvent, high quality TIPS-PEN films were printed at a very low substrate temperature of 35 °C. Saturated field-effect mobility measured with top-contact thin-film transistor structure shows a narrow distribution and a maximum of 0.78 cm{sup 2}V{sup −1} s{sup −1}, which confirmed the film growth on the hydrophobic substrate with increased crystal coverage and continuity under the optimized process condition. - Highlights: • Hydrophobic substrates were employed to inhibit the coffee-ring effect. • Contact-line pinning is primarily controlled by the dispersion force. • Solvent selection is critical to crystal coverage of the printed film. • High performance and uniformity are achieved by process optimization.

  10. Rapid Guest Exchange and Ultra-Low Surface Tension Solvents Optimize Metal-Organic Framework Activation.

    Science.gov (United States)

    Ma, Jialiu; Kalenak, Andre P; Wong-Foy, Antek G; Matzger, Adam J

    2017-11-13

    Exploratory research into the critical steps in metal-organic framework (MOF) activation involving solvent exchange and solvent evacuation are reported. It is discovered that solvent exchange kinetics are extremely fast, and minutes rather days are appropriate for solvent exchange in many MOFs. It is also demonstrated that choice of a very low surface tension solvent is critical in successfully activating challenging MOFs. MOFs that have failed to be activated previously can achieve predicted surface areas provided that lower surface tension solvents, such as n-hexane and perfluoropentane, are applied. The insights herein aid in the efficient activation of MOFs in both laboratory and industrial settings and provide best practices for avoiding structural collapse. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Recycling of Palladium from Spent Catalysts Using Solvent Extraction—Some Critical Points

    Directory of Open Access Journals (Sweden)

    Ana Paula Paiva

    2017-11-01

    Full Text Available Electrical and electronics equipment and automotive and industrial catalysts are some examples of top technological devices whose functioning rely on the use of platinum-group metals (PGMs. The PGMs’ high economic value and difficult to replace technological properties, together with their scarcity in the Earth’s crust, justify concerns about their critical condition and reinforce the importance of developing recycling practices for PGM end-of-life materials. This article presents and discusses recent advances regarding the use of hydrometallurgical solvent extraction to recover one PGM, palladium, from spent catalysts. Two different tendencies are implicit in the literature concerning Pd(II extraction: a few groups focus on the adjustment and optimization of current commercial extractants, while others prefer to design new extracting compounds. Actually, the leach solutions obtained from the treatment of anthropogenic materials generally exhibit different compositions when compared to those coming from the primary resources. The pros and cons of both approaches are critically discussed, and the assumptions backing some of the reported achievements are also appraised.

  12. Optimal Biocompatible Solvent Design by Mixed-integer Hybrid Differential Evolution

    Directory of Open Access Journals (Sweden)

    Hou-Chieh Cheng

    2008-04-01

    Full Text Available In this study, a flexible optimization approach is introduced to design an optimal biocompatible solvent for an extractive fermentation process with cell-recycling. The optimal process/solvent design problem is formulated as a mixed-integer nonlinear programming model in which performance requirements of the compounds are reflected in the objectives and the constraints. A flexible or fuzzy optimization approach is applied to soften the rigid requirement for maximization of the production rate, extraction efficiency and to consider the solvent utilization rate as the softened inequality constraint to the process/solvent design problem. Such a trade-off problem is then converted to the goal attainment problem, which is described as the constrained mixed-integer nonlinear programming (MINLP problem. Mixed-integer hybrid differential evolution with multiplier updating method is introduced to solve the constrained MINLP problem. The adaptive penalty updating scheme is more efficient to achieve a global design.

  13. Optimization of soy isoflavone extraction with different solvents using the simplex-centroid mixture design.

    Science.gov (United States)

    Yoshiara, Luciane Yuri; Madeira, Tiago Bervelieri; Delaroza, Fernanda; da Silva, Josemeyre Bonifácio; Ida, Elza Iouko

    2012-12-01

    The objective of this study was to optimize the extraction of different isoflavone forms (glycosidic, malonyl-glycosidic, aglycone and total) from defatted cotyledon soy flour using the simplex-centroid experimental design with four solvents of varying polarity (water, acetone, ethanol and acetonitrile). The obtained extracts were then analysed by high-performance liquid chromatography. The profile of the different soy isoflavones forms varied with different extractions solvents. Varying the solvent or mixture used, the extraction of different isoflavones was optimized using the centroid-simplex mixture design. The special cubic model best fitted to the four solvents and its combination for soy isoflavones extraction. For glycosidic isoflavones extraction, the polar ternary mixture (water, acetone and acetonitrile) achieved the best extraction; malonyl-glycosidic forms were better extracted with mixtures of water, acetone and ethanol. Aglycone isoflavones, water and acetone mixture were best extracted and total isoflavones, the best solvents were ternary mixture of water, acetone and ethanol.

  14. Optimal (Solvent) Mixture Design through a Decomposition Based CAMD methodology

    OpenAIRE

    Achenie, L.; Arunprakash T. Karunanithi; Gani, Rafiqul

    2004-01-01

    Computer Aided Molecular/Mixture design (CAMD) is one of the most promising techniques for solvent design and selection. A decomposition based CAMD methodology has been formulated where the mixture design problem is solved as a series of molecular and mixture design sub-problems. This approach is able to overcome most of the difficulties associated with the solution of mixture design problems. The new methodology has been illustrated with the help of a case study involving the design of solve...

  15. Radiation Dose Optimization For Critical Organs

    Science.gov (United States)

    Khodadadegan, Yasaman

    Ionizing radiation used in the patient diagnosis or therapy has negative effects on the patient body in short term and long term depending on the amount of exposure. More than 700,000 examinations are everyday performed on Interventional Radiology modalities, however; there is no patient-centric information available to the patient or the Quality Assurance for the amount of organ dose received. In this study, we are exploring the methodologies to systematically reduce the absorbed radiation dose in the Fluoroscopically Guided Interventional Radiology procedures. In the first part of this study, we developed a mathematical model which determines a set of geometry settings for the equipment and a level for the energy during a patient exam. The goal is to minimize the amount of absorbed dose in the critical organs while maintaining image quality required for the diagnosis. The model is a large-scale mixed integer program. We performed polyhedral analysis and derived several sets of strong inequalities to improve the computational speed and quality of the solution. Results present the amount of absorbed dose in the critical organ can be reduced up to 99% for a specific set of angles. In the second part, we apply an approximate gradient method to simultaneously optimize angle and table location while minimizing dose in the critical organs with respect to the image quality. In each iteration, we solve a sub-problem as a MIP to determine the radiation field size and corresponding X-ray tube energy. In the computational experiments, results show further reduction (up to 80%) of the absorbed dose in compare with previous method. Last, there are uncertainties in the medical procedures resulting imprecision of the absorbed dose. We propose a robust formulation to hedge from the worst case absorbed dose while ensuring feasibility. In this part, we investigate a robust approach for the organ motions within a radiology procedure. We minimize the absorbed dose for the critical

  16. A new decomposition-based computer-aided molecular/mixture design methodology for the design of optimal solvents and solvent mixtures

    DEFF Research Database (Denmark)

    Karunanithi, A.T.; Achenie, L.E.K.; Gani, Rafiqul

    2005-01-01

    This paper presents a novel computer-aided molecular/mixture design (CAMD) methodology for the design of optimal solvents and solvent mixtures. The molecular/mixture design problem is formulated as a mixed integer nonlinear programming (MINLP) model in which a performance objective is to be optim......This paper presents a novel computer-aided molecular/mixture design (CAMD) methodology for the design of optimal solvents and solvent mixtures. The molecular/mixture design problem is formulated as a mixed integer nonlinear programming (MINLP) model in which a performance objective...... is to be optimized subject to structural, property, and process constraints. The general molecular/mixture design problem is divided into two parts. For optimal single-compound design, the first part is solved. For mixture design, the single-compound design is first carried out to identify candidates...... and then the second part is solved to determine the optimal mixture. The decomposition of the CAMD MINLP model into relatively easy to solve subproblems is essentially a partitioning of the constraints from the original set. This approach is illustrated through two case studies. The first case study involves...

  17. Composition optimization and stability testing of a parenteral antifungal solution based on a ternary solvent system.

    Science.gov (United States)

    Kovács, Kristóf; Antal, István; Stampf, György; Klebovich, Imre; Ludányi, Krisztina

    2010-03-01

    An intravenous solution is a dosage forms intended for administration into the bloodstream. This route is the most rapid and the most bioavailable method of getting drugs into systemic circulation, and therefore it is also the most liable to cause adverse effects. In order to reduce the possibility of side effects and to ensure adequate clinical dosage of the formulation, the primarily formulated composition should be optimized. It is also important that the composition should retain its therapeutic effectiveness and safety throughout the shelf-life of the product. This paper focuses on the optimization and stability testing of a parenteral solution containing miconazole and ketoconazole solubilized with a ternary solvent system as model drugs. Optimization of the solvent system was performed based on assessing the risk/benefit ratio of the composition and its properties upon dilution. Stability tests were conducted based on the EMEA (European Medicines Agency) "guideline on stability testing: stability testing of existing active substances and related finished products". Experiments show that both the amount of co-solvent and surface active agent of the solvent system could substantially be reduced, while still maintaining adequate solubilizing power. It is also shown that the choice of various containers affects the stability of the compositions. It was concluded that by assessing the risk/benefit ratio of solubilizing power versus toxicity, the concentration of excipients could be considerably decreased while still showing a powerful solubilizing effect. It was also shown that a pharmaceutically acceptable shelf-life could be assigned to the composition, indicating good long-term stability.

  18. Optimization by response surface methodology of lutein recovery from paprika leaves using accelerated solvent extraction.

    Science.gov (United States)

    Kang, Jae-Hyun; Kim, Suna; Moon, BoKyung

    2016-08-15

    In this study, we used response surface methodology (RSM) to optimize the extraction conditions for recovering lutein from paprika leaves using accelerated solvent extraction (ASE). The lutein content was quantitatively analyzed using a UPLC equipped with a BEH C18 column. A central composite design (CCD) was employed for experimental design to obtain the optimized combination of extraction temperature (°C), static time (min), and solvent (EtOH, %). The experimental data obtained from a twenty sample set were fitted to a second-order polynomial equation using multiple regression analysis. The adjusted coefficient of determination (R(2)) for the lutein extraction model was 0.9518, and the probability value (p=0.0000) demonstrated a high significance for the regression model. The optimum extraction conditions for lutein were temperature: 93.26°C, static time: 5 min, and solvent: 79.63% EtOH. Under these conditions, the predicted extraction yield of lutein was 232.60 μg/g. Copyright © 2016 Elsevier Ltd. All rights reserved.

  19. Optimal Furosemide Therapy in Critically Ill infants

    NARCIS (Netherlands)

    M.M.J. van der Vorst

    2007-01-01

    textabstractFurosemide as continuous infusion is used in infants after cardiopulmonary bypass (CPB) surgery and during extracorporeal membrane oxygenation (ECMO). The currently used regimens which start with low dose (0.05 - 0.1 mg/kg.hr) may not be optimal in this group of patients with

  20. Optimizing the electrical properties of PEDOT:PSS films by co-solvents and their application in polymer photovoltaic cells

    Science.gov (United States)

    Pathak, C. S.; Singh, J. P.; Singh, R.

    2017-09-01

    A simple optimizing approach that improves the electrical properties of poly (3,4-ethylenedioxylthiophene):poly(styrenesulfonate) (PEDOT:PSS) films and their application in heterojunction diodes and polymer photovoltaic cells is presented in this paper. The optimizing process is performed by mixing the organic solvents n-methyl-2-pyrrolidone and methanol along with dimethyl sulfoxide into PEDOT:PSS solution achieving the facile combination of the solvent effect. Electrical conductivity varies from 0.16 to 194 S/cm by variation in the concentration of n-methyl-2-pyrrolidone. It is shown that the enhancement in conductivity of PEDOT:PSS films with co-solvents by three orders of magnitude is achieved compared to pristine PEDOT:PSS with transparency >92% in the visible region. The heterojunction diodes fabricated with co-solvents studied in this work showed rectifying behavior, and polymer photovoltaic cells fabricated with the co-solvents exhibited photovoltaic performance.

  1. Aquifer washing by micellar solutions: 1. Optimization of alcohol-surfactant-solvent solutions

    Science.gov (United States)

    Martel, Richard; Gélinas, Pierre J.; Desnoyers, Jacques E.

    1998-03-01

    Phase diagrams were used for the formulation of alcohol-surfactant-solvent and to identify the DNAPL (Dense Non Aqueous Phase Liquid) extraction zones. Four potential extraction zones of Mercier DNAPL, a mixture of heavy aliphatics, aromatics and chlorinated hydrocarbons, were identified but only one microemulsion zone showed satisfactory DNAPL recovery in sand columns. More than 90 sand column experiments were performed and demonstrate that: (1) neither surfactant in water, alcohol-surfactant solutions, nor pure solvent can effectively recover Mercier DNAPL and that only alcohol-surfactant-solvent solutions are efficient; (2) adding salts to alcohol-surfactant or to alcohol-surfactant-solvent solutions does not have a beneficial effect on DNAPL recovery; (3) washing solution formulations are site specific and must be modified if the surface properties of the solids (mineralogy) change locally, or if the interfacial behavior of liquids (type of oil) changes; (4) high solvent concentrations in washing solutions increase DNAPL extraction but also increase their cost and decrease their density dramatically; (5) maximum DNAPL recovery is observed with alcohol-surfactant-solvent formulations which correspond to the maximum solubilization in Zone C of the phase diagram; (6) replacing part of surfactant SAS by the alcohol n-butanol increases washing solution efficiency and decreases the density and the cost of solutions; (7) replacing part of n-butanol by the nonionic surfactant HOES decreases DNAPL recovery and increases the cost of solutions; (8) toluene is a better solvent than D-limonene because it increases DNAPL recovery and decreases the cost of solutions; (9) optimal alcohol-surfactant-solvent solutions contain a mixture of solvents in a mass ratio of toluene to D-limonene of one or two. Injection of 1.5 pore volumes of the optimal washing solution of n-butanol-SAS-toluene- D-limonene in water can recover up to 95% of Mercier DNAPL in sand columns. In the first

  2. Optimizing information processing in neuronal networks beyond critical states.

    Science.gov (United States)

    Ferraz, Mariana Sacrini Ayres; Melo-Silva, Hiago Lucas Cardeal; Kihara, Alexandre Hiroaki

    2017-01-01

    Critical dynamics have been postulated as an ideal regime for neuronal networks in the brain, considering optimal dynamic range and information processing. Herein, we focused on how information entropy encoded in spatiotemporal activity patterns may vary in critical networks. We employed branching process based models to investigate how entropy can be embedded in spatiotemporal patterns. We determined that the information capacity of critical networks may vary depending on the manipulation of microscopic parameters. Specifically, the mean number of connections governed the number of spatiotemporal patterns in the networks. These findings are compatible with those of the real neuronal networks observed in specific brain circuitries, where critical behavior is necessary for the optimal dynamic range response but the uncertainty provided by high entropy as coded by spatiotemporal patterns is not required. With this, we were able to reveal that information processing can be optimized in neuronal networks beyond critical states.

  3. Optimizing information processing in neuronal networks beyond critical states.

    Directory of Open Access Journals (Sweden)

    Mariana Sacrini Ayres Ferraz

    Full Text Available Critical dynamics have been postulated as an ideal regime for neuronal networks in the brain, considering optimal dynamic range and information processing. Herein, we focused on how information entropy encoded in spatiotemporal activity patterns may vary in critical networks. We employed branching process based models to investigate how entropy can be embedded in spatiotemporal patterns. We determined that the information capacity of critical networks may vary depending on the manipulation of microscopic parameters. Specifically, the mean number of connections governed the number of spatiotemporal patterns in the networks. These findings are compatible with those of the real neuronal networks observed in specific brain circuitries, where critical behavior is necessary for the optimal dynamic range response but the uncertainty provided by high entropy as coded by spatiotemporal patterns is not required. With this, we were able to reveal that information processing can be optimized in neuronal networks beyond critical states.

  4. Optimized Li-Ion Electrolytes Containing Fluorinated Ester Co-Solvents

    Science.gov (United States)

    Prakash, G. K. Surya; Smart, Marshall; Smith, Kiah; Bugga, Ratnakumar

    2010-01-01

    A number of experimental lithium-ion cells, consisting of MCMB (meso-carbon microbeads) carbon anodes and LiNi(0.8)Co(0.2)O2 cathodes, have been fabricated with increased safety and expanded capability. These cells serve to verify and demonstrate the reversibility, low-temperature performance, and electrochemical aspects of each electrode as determined from a number of electrochemical characterization techniques. A number of Li-ion electrolytes possessing fluorinated ester co-solvents, namely trifluoroethyl butyrate (TFEB) and trifluoroethyl propionate (TFEP), were demonstrated to deliver good performance over a wide temperature range in experimental lithium-ion cells. The general approach taken in the development of these electrolyte formulations is to optimize the type and composition of the co-solvents in ternary and quaternary solutions, focusing upon adequate stability [i.e., EC (ethylene carbonate) content needed for anode passivation, and EMC (ethyl methyl carbonate) content needed for lowering the viscosity and widening the temperature range, while still providing good stability], enhancing the inherent safety characteristics (incorporation of fluorinated esters), and widening the temperature range of operation (the use of both fluorinated and non-fluorinated esters). Further - more, the use of electrolyte additives, such as VC (vinylene carbonate) [solid electrolyte interface (SEI) promoter] and DMAc (thermal stabilizing additive), provide enhanced high-temperature life characteristics. Multi-component electrolyte formulations enhance performance over a temperature range of -60 to +60 C. With the need for more safety with the use of these batteries, flammability was a consideration. One of the solvents investigated, TFEB, had the best performance with improved low-temperature capability and high-temperature resilience. This work optimized the use of TFEB as a co-solvent by developing the multi-component electrolytes, which also contain non

  5. Outcomes Related to the Use of Frozen Plasma or Pooled Solvent/Detergent-Treated Plasma in Critically Ill Children

    DEFF Research Database (Denmark)

    Camazine, Maraya N; Karam, Oliver; Colvin, Ryan

    2017-01-01

    OBJECTIVE: To determine if the use of fresh frozen plasma/frozen plasma 24 hours compared to solvent detergent plasma is associated with international normalized ratio reduction or ICU mortality in critically ill children. DESIGN: This is an a priori secondary analysis of a prospective, observati...

  6. Solvent Optimization for Efficient Enzymatic Monoacylglycerol Production Based on a Glycerolysis Reaction

    DEFF Research Database (Denmark)

    Damstrup, Marianne; Jensen, Tine; Sparsø, Flemming V.

    2005-01-01

    This study was aimed at screening solvent systems of varying polarities to identify suitable solvents for efficient and practical enzymatic glycerolysis. Several pure solvents and solvent mixtures were screened in a batch reaction system consisting of glycerol, sunflower oil, and Novozymo (R) 435...

  7. Outcomes Related to the Use of Frozen Plasma or Pooled Solvent/Detergent-Treated Plasma in Critically Ill Children.

    Science.gov (United States)

    Camazine, Maraya N; Karam, Oliver; Colvin, Ryan; Leteurtre, Stephane; Demaret, Pierre; Tucci, Marisa; Muszynski, Jennifer A; Stanworth, Simon; Spinella, Philip C

    2017-05-01

    To determine if the use of fresh frozen plasma/frozen plasma 24 hours compared to solvent detergent plasma is associated with international normalized ratio reduction or ICU mortality in critically ill children. This is an a priori secondary analysis of a prospective, observational study. Study groups were defined as those transfused with either fresh frozen plasma/frozen plasma 24 hours or solvent detergent plasma. Outcomes were international normalized ratio reduction and ICU mortality. Multivariable logistic regression was used to determine independent associations. One hundred one PICUs in 21 countries. All critically ill children admitted to a participating unit were included if they received at least one plasma unit during six predefined 1-week (Monday to Friday) periods. All children were exclusively transfused with either fresh frozen plasma/frozen plasma 24 hours or solvent detergent plasma. None. There were 443 patients enrolled in the study. Twenty-four patients (5%) were excluded because no plasma type was recorded; the remaining 419 patients were analyzed. Fresh frozen plasma/frozen plasma 24 hours group included 357 patients, and the solvent detergent plasma group included 62 patients. The median (interquartile range) age and weight were 1 year (0.2-6.4) and 9.4 kg (4.0-21.1), respectively. There was no difference in reason for admission, severity of illness score, pretransfusion international normalized ratio, or lactate values; however, there was a difference in primary indication for plasma transfusion (p plasma/frozen plasma 24 hours and solvent detergent plasma study groups, -0.2 (-0.4 to 0) and -0.2 (-0.3 to 0), respectively (p = 0.80). ICU mortality was lower in the solvent detergent plasma versus fresh frozen plasma/frozen plasma 24 hours groups, 14.5% versus 29.1%%, respectively (p = 0.02). Upon adjusted analysis, solvent detergent plasma transfusion was independently associated with reduced ICU mortality (odds ratio, 0.40; 95% CI, 0

  8. Optimal recovery sequencing for critical infrastructure resilience assessment.

    Energy Technology Data Exchange (ETDEWEB)

    Vugrin, Eric D.; Brown, Nathanael J. K.; Turnquist, Mark Alan (Cornell University, Ithaca, NY)

    2010-09-01

    Critical infrastructure resilience has become a national priority for the U. S. Department of Homeland Security. System resilience has been studied for several decades in many different disciplines, but no standards or unifying methods exist for critical infrastructure resilience analysis. This report documents the results of a late-start Laboratory Directed Research and Development (LDRD) project that investigated the identification of optimal recovery strategies that maximize resilience. To this goal, we formulate a bi-level optimization problem for infrastructure network models. In the 'inner' problem, we solve for network flows, and we use the 'outer' problem to identify the optimal recovery modes and sequences. We draw from the literature of multi-mode project scheduling problems to create an effective solution strategy for the resilience optimization model. We demonstrate the application of this approach to a set of network models, including a national railroad model and a supply chain for Army munitions production.

  9. "Cruel Optimism" and Contemporary Australian Critical Theory in Educational Research

    Science.gov (United States)

    Rasmussen, Mary Lou

    2015-01-01

    "Cruel optimism" is a term coined by Lauren Berlant. In conceptualizing this term, Berlant draws on the resources of critical theory to interrogate people's desires for things they think may improve their lot, but actually act as obstacles to flourishing. This notion may be useful for analysing the current state of education in…

  10. Reducing refinery CO2 emissions through amine solvent upgrade and optimization

    Energy Technology Data Exchange (ETDEWEB)

    Alonso, Thiago V.; Valenzuela, Michelle [The Dow Chemical Company, Midland, MI (United States)

    2012-07-01

    Regional initiatives are underway to reduce and limit the emissions of greenhouse gases. With CO2 emissions making up over 80% of the greenhouse gases, cap-and-trade programs will focus on those industries that consume the most energy. Refineries are among the top energy consumers and are seeking opportunities to reduce usage. With tightening margins, energy management programs will not only help refineries meet CO{sub 2} emission regulations, but can also provide a competitive advantage. With the trend towards heavier and higher sulfur containing crudes, refineries are increasing processing capabilities, which can include capital-intensive projects and additional energy consumption. Energy conservation plans should include optimization of these processes. One area to consider includes the acid gas removal systems in refineries. Through the selection and use of optimal solvents and implementation of energy efficiency techniques, which require minimal capital investment and expenditures, refineries can reduce energy usage, overall CO{sub 2} emissions, and total cost in acid gas systems. This paper will discuss these approaches and share case studies detailing the implementation and results. (author)

  11. Optimization of the solvent-based dissolution method to sample volatile organic compound vapors for compound-specific isotope analysis.

    Science.gov (United States)

    Bouchard, Daniel; Wanner, Philipp; Luo, Hong; McLoughlin, Patrick W; Henderson, James K; Pirkle, Robert J; Hunkeler, Daniel

    2017-10-20

    The methodology of the solvent-based dissolution method used to sample gas phase volatile organic compounds (VOC) for compound-specific isotope analysis (CSIA) was optimized to lower the method detection limits for TCE and benzene. The sampling methodology previously evaluated by [1] consists in pulling the air through a solvent to dissolve and accumulate the gaseous VOC. After the sampling process, the solvent can then be treated similarly as groundwater samples to perform routine CSIA by diluting an aliquot of the solvent into water to reach the required concentration of the targeted contaminant. Among solvents tested, tetraethylene glycol dimethyl ether (TGDE) showed the best aptitude for the method. TGDE has a great affinity with TCE and benzene, hence efficiently dissolving the compounds during their transition through the solvent. The method detection limit for TCE (5±1μg/m3) and benzene (1.7±0.5μg/m3) is lower when using TGDE compared to methanol, which was previously used (385μg/m3 for TCE and 130μg/m3 for benzene) [2]. The method detection limit refers to the minimal gas phase concentration in ambient air required to load sufficient VOC mass into TGDE to perform δ13C analysis. Due to a different analytical procedure, the method detection limit associated with δ37Cl analysis was found to be 156±6μg/m3 for TCE. Furthermore, the experimental results validated the relationship between the gas phase TCE and the progressive accumulation of dissolved TCE in the solvent during the sampling process. Accordingly, based on the air-solvent partitioning coefficient, the sampling methodology (e.g. sampling rate, sampling duration, amount of solvent) and the final TCE concentration in the solvent, the concentration of TCE in the gas phase prevailing during the sampling event can be determined. Moreover, the possibility to analyse for TCE concentration in the solvent after sampling (or other targeted VOCs) allows the field deployment of the sampling method

  12. Optimized Solvent for Energy-Efficient, Environmentally-Friendly Capture of CO{sub 2} at Coal-Fired Power Plants

    Energy Technology Data Exchange (ETDEWEB)

    Farthing, G. A.; Rimpf, L. M.

    2014-04-30

    The overall goal of this project, as originally proposed, was to optimize the formulation of a novel solvent as a critical enabler for the cost-effective, energy-efficient, environmentally-friendly capture of CO{sub 2} at coal-fired utility plants. Aqueous blends of concentrated piperazine (PZ) with other compounds had been shown to exhibit high rates of CO{sub 2} absorption, low regeneration energy, and other desirable performance characteristics during an earlier 5-year development program conducted by B&W. The specific objective of this project was to identify PZ-based solvent formulations that globally optimize the performance of coal-fired power plants equipped with CO{sub 2} scrubbing systems. While previous solvent development studies have tended to focus on energy consumption and absorber size, important issues to be sure, the current work seeks to explore, understand, and optimize solvent formulation across the full gamut of issues related to commercial application of the technology: capital and operating costs, operability, reliability, environmental, health and safety (EH&S), etc. Work on the project was intended to be performed under four budget periods. The objective of the work in the first budget period has been to identify several candidate formulations of a concentrated PZ-based solvent for detailed characterization and evaluation. Work in the second budget period would generate reliable and comprehensive property and performance data for the identified formulations. Work in the third budget period would quantify the expected performance of the selected formulations in a commercial CO{sub 2} scrubbing process. Finally, work in the fourth budget period would provide a final technology feasibility study and a preliminary technology EH&S assessment. Due to other business priorities, however, B&W has requested that this project be terminated at the end of the first budget period. This document therefore serves as the final report for this project. It

  13. Response Surface Optimization of Rotenone Using Natural Alcohol-Based Deep Eutectic Solvent as Additive in the Extraction Medium Cocktail

    Directory of Open Access Journals (Sweden)

    Zetty Shafiqa Othman

    2017-01-01

    Full Text Available Rotenone is a biopesticide with an amazing effect on aquatic life and insect pests. In Asia, it can be isolated from Derris species roots (Derris elliptica and Derris malaccensis. The previous study revealed the comparable efficiency of alcohol-based deep eutectic solvent (DES in extracting a high yield of rotenone (isoflavonoid to binary ionic liquid solvent system ([BMIM]OTf and organic solvent (acetone. Therefore, this study intends to analyze the optimum parameters (solvent ratio, extraction time, and agitation rate in extracting the highest yield of rotenone extract at a much lower cost and in a more environmental friendly method by using response surface methodology (RSM based on central composite rotatable design (CCRD. By using RSM, linear polynomial equations were obtained for predicting the concentration and yield of rotenone extracted. The verification experiment confirmed the validity of both of the predicted models. The results revealed that the optimum conditions for solvent ratio, extraction time, and agitation rate were 2 : 8 (DES : acetonitrile, 19.34 hours, and 199.32 rpm, respectively. At the optimum condition of the rotenone extraction process using DES binary solvent system, this resulted in a 3.5-fold increase in a rotenone concentration of 0.49 ± 0.07 mg/ml and yield of 0.35 ± 0.06 (%, w/w as compared to the control extract (acetonitrile only. In fact, the rotenone concentration and yield were significantly influenced by binary solvent ratio and extraction time (P<0.05 but not by means of agitation rate. For that reason, the optimal extraction condition using alcohol-based deep eutectic solvent (DES as a green additive in the extraction medium cocktail has increased the potential of enhancing the rotenone concentration and yield extracted.

  14. Optimal Dynamical Range of Excitable Networks at Criticality

    CERN Document Server

    Kinouchi, Osame

    2006-01-01

    A recurrent idea in the study of complex systems is that optimal information processing is to be found near bifurcation points or phase transitions. However, this heuristic hypothesis has few (if any) concrete realizations where a standard and biologically relevant quantity is optimized at criticality. Here we give a clear example of such a phenomenon: a network of excitable elements has its sensitivity and dynamic range maximized at the critical point of a non-equilibrium phase transition. Our results are compatible with the essential role of gap junctions in olfactory glomeruli and retinal ganglionar cell output. Synchronization and global oscillations also appear in the network dynamics. We propose that the main functional role of electrical coupling is to provide an enhancement of dynamic range, therefore allowing the coding of information spanning several orders of magnitude. The mechanism could provide a microscopic neural basis for psychophysical laws.

  15. Choline chloride-based deep eutectic solvents as additives for optimizing chromatographic behavior of caffeic acid

    Energy Technology Data Exchange (ETDEWEB)

    Li, Guizhen; Zhu, Tao; Lei, Yingjie [Tianjin University of Technology, Tianjin (China)

    2015-10-15

    A series of deep eutectic solvents (DESs) were prepared using glycerol and choline chloride (ChCl), and Fourier transform infrared spectrometer (FT-IR) was used to analyze the spectra of glycerol, choline chloride and DESs based on glycerol and choline chloride. Then DESs were used as the additives of mobile phase to optimize chromatographic behavior of caffeic acid in high performance liquid chromatography (HPLC). A 17-run Box-Behnken design (BBD) was employed to evaluate effect of DESs as additives by analyzing the maximum theoretical plate number. Three factors, reaction temperature (60 .deg. C, 80 .deg. C, 100 .deg. C), molar ratio of glycerol and choline chloride (2 : 1, 3 : 1, 4 : 1, n/n), and volume percent of additives (0.05%, 0.10%, 0.15%, v/v), were investigated in BBD. The optimum experiment condition was that of reaction temperature (80 .deg. C), molar ratio of glycerol and ChCl (3 : 1, n/n), and volume percent of additive (0.10%, v/v). The mean chromatographic theoretical plate number of the caffeic acid this condition was 1567.5, and DESs as additives shorten the retention time and modify the chromatogram shape, proving DESs as additives for effective theoretical plate number and column efficiency in HPLC.

  16. Crystal morphology optimization of thiamine hydrochloride in solvent system: Experimental and molecular dynamics simulation studies

    Science.gov (United States)

    Yang, Yang; Han, Dandan; Du, Shichao; Wu, Songgu; Gong, Junbo

    2018-01-01

    Thiamine hydrochloride (THCL) was produced in methanol accompanied with agglomeration in industry, the plate like morphology of THCL in methanol was not deserve to have a good quality. Selecting a suitable solvent should be considered because solvent could be one of the essential factors to impact morphology. Methanol and methanol/ethyl acetate solvent (0.2 vol fraction of methanol) was selected as the solvent system in reactive crystallization of THCL. The experiment results show the THCL crystal morphology in methanol/ethyl acetate solvent system was granular and more regular than that in methanol. In order to explicate the different crystal morphology in different solvents, molecular dynamics (MD) simulation was introduced to simulate crystal morphology in different solvents. The attachment energy (AE) model was employed to investigate the morphology of THCL under vacuum conditions, methanol and methanol/ethyl acetate solvent conditions, respectively. The simulation crystal morphology was in a good agreement with that of experimented. The particle of THCL in methanol/ethyl acetate solvent has less tendency to agglomeration, and then it is favorable to the downstream process, such as filtration, storage and transportation.

  17. Optimization of coffee oil extraction from spent coffee grounds using four solvents and prototype-scale extraction using circulation process

    Directory of Open Access Journals (Sweden)

    Krit Somnuk

    2017-06-01

    Full Text Available The optimization of two parameters—espresso coffee oil extraction time and the ratio of dried spent coffee grounds (DSCG-to-solvent—were conducted on DSCG employing four solvents. Extracted yields were investigated using response surface methodology. The two independent variables—ratio of DSCG-to-solvent (5.1–24.9 g/g and extraction time (0.2–39.8 min—were optimized in the batch mode. The predicted model was verified using actual experiments. The experimental yields achieved were 14.7 percent by weight (wt%; using hexane, 13.1 wt% (using anhydrous ethanol, 11.8 wt% (using hydrous ethanol, and 7.5 wt% (using methanol. Prototype extraction was tested using a circulation process. Approximately 11.8 wt% oil yield of prototype extraction could be obtained from DSCG under the optimal conditions of 30.4 min extraction time and 22.5 g/g ratio of DSCG-to-hexane from the laboratory-scale results. In this study, the miscella (the solution of coffee oil dissolved in the solvent from up to six successive extractions was investigated to determine the optimal oil extraction process. The repeated miscella from each successive extraction showed high efficiency and stability of coffee oil yield similar to that obtained using fresh hexane.

  18. Application of multicriteria decision analysis in solvent type optimization for chlorophenols determination with a dispersive liquid-liquid microextraction.

    Science.gov (United States)

    Bigus, Paulina; Namieśnik, Jacek; Tobiszewski, Marek

    2016-05-13

    This study presents a novel support tool for the optimization and development of analytical methods. The tool is based on multi-criteria decision analysis (MCDA), namely the Technique for Order of Preference by Similarity to the Ideal Solution (TOPSIS), that allows users to rank possible solutions according to their requirements. In this study, we performed rankings of pairs of eight extraction and three dispersive solvents used in DLLME for chlorophenols extraction from water samples. The first ranking involved sensitivity and precision of the method for each of the nine chlorophenols. The tool is a quantitative solution to the common analytical problem that the change of analytical performance results in better performance for some analytes and worse for others. The second ranking included the assessment of the greenness of each pair of solvents, based on toxicological, ecotoxicological and environmental persistence criteria. The third ranking was based on a combination of sensitivity, precision and greenness criteria. Heptane as an extraction solvent and acetone as a dispersive solvent were selected as the most appropriate ones. The TOPSIS tool is a successful, easy to implement, incorporation of green analytical chemistry values to analytical method optimization. Copyright © 2016 Elsevier B.V. All rights reserved.

  19. Optimization of the production of organic solvent-stable protease by Bacillus sphaericus DS11 with response surface methodology.

    Science.gov (United States)

    Liu, Shu; Fang, Yaowei; Lv, Mingsheng; Wang, Shujun; Chen, Li

    2010-10-01

    Response surface methodology (RSM) was employed to enhance the production of organic solvent-stable protease by Bacillus sphaericus DS11. A significant influence of glycerol, MgSO₄·7H₂O, and pH on organic solvent-stable protease production was noted with Plackett-Burman design. Then, a three-level Box-Behnken design was employed to optimize the medium composition and culture conditions for the production of the protease in shake-flask. Using this methodology, the quadratic regression model of producing organic solvent-stable protease was built and the optimal combinations of media constituents and culture conditions for maximum protease production were determined as glycerol 12.47 g/L, MgSO₄·7H₂O 0.73 g/L, and pH 8.25. Protease production obtained experimentally coincident with the predicted value and the model was proven to be adequate. The enhancement of protease from 465.06 U/mL to 1182.68 U/mL was achieved with the optimization procedure. Copyright © 2010 Elsevier Ltd. All rights reserved.

  20. Solvent Composition is Critical for Carbodiimide Cross-Linking of Hyaluronic Acid as an Ophthalmic Biomaterial

    Directory of Open Access Journals (Sweden)

    Jui-Yang Lai

    2012-10-01

    Full Text Available Hyaluronic acid (HA is one of the most important ophthalmic biomaterials, while also being used for tissue engineering and drug delivery. Although chemical cross-linking is an effective way to improve the material performance, it may as a consequence be detrimental to the living cells/tissues. Given that the cross-linking efficiency is mediated by the solvent composition during the chemical modification, this study aims to explore the stability and biocompatibility of carbodiimide cross-linked HA in relation to material processing conditions by varying the acetone/water volume ratio (from 70:30 to 95:5 at a constant 1-ethyl-3-(3-dimethyl aminopropyl carbodiimide (EDC concentration of 100 mM. Our results indicated that after the EDC treatment in the presence of an acetone/water mixture (85:15, v/v, the HA hydrogel membranes have the lowest equilibrium water content, the highest stress at break and the greatest resistance to hyaluronidase digestion. Live/Dead assays and pro-inflammatory cytokine expression analyses showed that the cross-linked HA hydrogel membranes, irrespective of the solvent composition, are compatible with human RPE cell lines without causing toxicity and inflammation. However, it should be noted that the test samples prepared by the cross-linking in the presence of acetone/water mixtures containing 70, 75, and 95 vol % of acetone slightly inhibit the metabolic activity of viable ARPE-19 cultures, probably due to the alteration in the ionic interaction between the medium nutrients and polysaccharide biomaterials. In summary, the water content, mechanical strength and RPE cell proliferative capacity strongly depends on the solvent composition for carbodiimide cross-linking of HA materials.

  1. ORGANIC-HIGH IONIC STRENGTH AQUEOUS SOLVENT SYSTEMS FOR SPIRAL COUNTER-CURRENT CHROMATOGRAPHY: GRAPHIC OPTIMIZATION OF PARTITION COEFFICIENT

    Science.gov (United States)

    Zeng, Yun; Liu, Gang; Ma, Ying; Chen, Xiaoyuan; Ito, Yoichiro

    2012-01-01

    A new series of organic-high ionic strength aqueous two-phase solvents systems was designed for separation of highly polar compounds by spiral high-speed counter-current chromatography. A total of 21 solvent systems composed of 1-butanol-ethanol-saturated ammonium sulfate-water at various volume ratios are arranged according to an increasing order of polarity. Selection of the two-phase solvent system for a single compound or a multiple sample mixture can be achieved by two steps of partition coefficient measurements using a graphic method. The capability of the method is demonstrated by optimization of partition coefficient for seven highly polar samples including tartrazine (K=0.77), tryptophan (K=1.00), methyl green (K= 0.93), tyrosine (0.81), metanephrine (K=0.89), tyramine (K=0.98), and normetanephrine (K=0.96). Three sulfonic acid components in D&C Green No. 8 were successfully separated by HSCCC using the graphic selection of the two-phase solvent system. PMID:23467197

  2. Application of 2k Full Factorial Design in Optimization of Solvent-Free Microwave Extraction of Ginger Essential Oil

    Directory of Open Access Journals (Sweden)

    Mumtaj Shah

    2014-01-01

    Full Text Available The solvent-free microwave extraction of essential oil from ginger was optimized using a 23 full factorial design in terms of oil yield to determine the optimum extraction conditions. Sixteen experiments were carried out with three varying parameters, extraction time, microwave power, and type of sample for two levels of each. A first order regression equation best fits the experimental data. The predicted values calculated by the regression model were in good agreement with the experimental values. The results showed that the extraction time is the most prominent factor followed by microwave power level and sample type for extraction process. An average of 0.25% of ginger oil can be extracted using current setup. The optimum conditions for the ginger oil extraction using SFME were the extraction time 30 minutes, microwave power level 640 watts, and sample type, crushed sample. Solvent-free microwave extraction proves a green and promising technique for essential oil extraction.

  3. Real-time monitoring of asphaltene deposition for solvent job cycle optimization

    NARCIS (Netherlands)

    Boer, J.P. de; Linden, R.J.P. van der; Renes, W.A.

    2015-01-01

    Asphaltene agglomeration and deposition is a complex process, leading to progressive production losses without mitigative actions. Injection of asphaltenes inhibitors (solvents) in the tubing is a common practice to avoid deposition in production tubing. This does however not avoid deposition in the

  4. Multiple responses optimization in the development of a headspace gas chromatography method for the determination of residual solvents in pharmaceuticals

    Directory of Open Access Journals (Sweden)

    Carla M. Teglia

    2015-10-01

    Full Text Available An efficient generic static headspace gas chromatography (HSGC method was developed, optimized and validated for the routine determination of several residual solvents (RS in drug substance, using a strategy with two sets of calibration. Dimethylsulfoxide (DMSO was selected as the sample diluent and internal standards were used to minimize signal variations due to the preparative step. A gas chromatograph from Agilent Model 6890 equipped with flame ionization detector (FID and a DB-624 (30 m×0.53 mm i.d., 3.00 µm film thickness column was used. The inlet split ratio was 5:1. The influencing factors in the chromatographic separation of the analytes were determined through a fractional factorial experimental design. Significant variables: the initial temperature (IT, the final temperature (FT of the oven and the carrier gas flow rate (F were optimized using a central composite design. Response transformation and desirability function were applied to find out the optimal combination of the chromatographic variables to achieve an adequate resolution of the analytes and short analysis time. These conditions were 30 °C for IT, 158 °C for FT and 1.90 mL/min for F. The method was proven to be accurate, linear in a wide range and very sensitive for the analyzed solvents through a comprehensive validation according to the ICH guidelines.

  5. Optimization of process parameters for supercritical fluid extraction of cholesterol from whole milk powder using ethanol as co-solvent.

    Science.gov (United States)

    Dey Paul, Indira; Jayakumar, Chitra; Niwas Mishra, Hari

    2016-12-01

    In spite of being highly nutritious, the consumption of milk is hindered because of its high cholesterol content, which is responsible for numerous cardiac diseases. Supercritical carbon dioxide using ethanol as co-solvent was employed to extract cholesterol from whole milk powder (WMP). This study was undertaken to optimize the process parameters of supercritical fluid extraction (SCFE), viz. extraction temperature, pressure and volume of ethanol. The cholesterol content of WMP was quantified using high-performance liquid chromatography. The impact of the extraction conditions on the fat content (FC), solubility index (SI) and lightness (L*) of the SCFE-treated WMP were also investigated. The process parameters were optimized using response surface methodology. About 46% reduction in cholesterol was achieved at the optimized conditions of 48 °C, 17 MPa and 31 mL co-solvent; flow rate of expanded CO2 , static time and dynamic time of extraction were 6 L min-1 , 10 min and 80 min respectively. The treated WMP retained its FC, SI, and L* at moderate limits of 183.67 g kg-1 , 96.3% and 96.90, respectively. This study demonstrated the feasibility of ethanol-modified SCFE of cholesterol from WMP with negligible changes in its physicochemical properties. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

  6. Optimizing the Dispersion Conditions of SWCNTs in Aqueous Solution of Surfactants and Organic Solvents

    Directory of Open Access Journals (Sweden)

    Md. Mahfuzur Rahman

    2014-01-01

    Full Text Available The optimum concentration of surfactants in aqueous medium and the optimum sonication time for organic medium to achieve the best dispersion of SWCNTs are investigated in this study. Scanning electron microscope (SEM, atomic force microscope (AFM, and UV-vis-NIR study show that the optimum surfactant concentrations to achieve best dispersion for 0.25 mg/mL of SWCNTs are 9-10 mg/mL for (sodium dodecylbenzenesulfonate (SDBS and 8-9 mg/mL for (sodium deoxycholate (DOC. The diameter of the SWCNT lies between 0.7 and 2.5 nm in the case of aqueous solvent, which is in good agreement with the chirality. Moreover, SEM analysis reveals the presence of well-dispersed nanotubes along with some amount of surfactant particles; that is, some nanotubes might be covered with surfactants. Best dispersion of SWCNTs in organic solvents (1,2-Dichloroethane (DCE and N,N-Dimethylformamide (DMF is achieved by four hours of tip sonication. It realized that organic solvents provide pure SWCNTs after drying, which may possibly have SWCNTs with intrinsic properties.

  7. Optimization of ultrasonic-stimulated solvent extraction of sinigrin from Indian mustard seed (Brassica Juncea L.) using response surface methodology.

    Science.gov (United States)

    Wang, Tianxin; Liang, Hao; Yuan, Qipeng

    2011-01-01

    Sinigrin, a major glucosinolate present in Indian mustard (Brassica juncea L.) seeds as the precursor of the anticancer compound allyl isothiocyanate, shows a wide range of biological activities. It's necessary to optimize the extraction methods and conditions, in order to improve the extraction productivity and save raw material. To systemically investigate and optimize the most important factors affected the productivity of sinigrin in the process of extraction using response surface methodology. The ranges of three main factors including the ethanol concentration, extraction time and extraction temperature were selected by the one-factor-at-a-time method. The conditions of ultrasonic-stimulated extraction of sinigrin from defatted Indian mustard seed powder were optimized by Box-Behnken design to obtain the maximum productivity. The predicted productivity (3.81%) was obtained using 57% ethanol concentration at 81 °C for 60 min, with the coefficient of the model R² > 0.96 (n = 17). The actual productivity (3.84 ± 0.02%) of sinigrin under the optimized condition was increased by 70.67% compared with the result of conventional extraction. Meanwhile, HPLC, UV and IR were applied to examine if there is a difference between the ultrasonic-stimulated solvent extraction and conventional extraction, and the improvement of productivity of sinigrin depended on the destruction of cell wall caused by the elimination of outer pectinous material was explained by SEM and composition content analysis. The ultrasonic-stimulated solvent extraction was suggested to be a promising method to improve the productivity of sinigrin. And the results demonstrated that sinigrin productivity may be related to pectinous materials existed in the seeds. Copyright © 2010 John Wiley & Sons, Ltd.

  8. Optimal Workflow Scheduling in Critical Infrastructure Systems with Neural Networks

    Directory of Open Access Journals (Sweden)

    S. Vukmirović

    2012-04-01

    Full Text Available Critical infrastructure systems (CISs, such as power grids, transportation systems, communication networks and water systems are the backbone of a country’s national security and industrial prosperity. These CISs execute large numbers of workflows with very high resource requirements that can span through different systems and last for a long time. The proper functioning and synchronization of these workflows is essential since humanity’s well-being is connected to it. Because of this, the challenge of ensuring availability and reliability of these services in the face of a broad range of operating conditions is very complicated. This paper proposes an architecture which dynamically executes a scheduling algorithm using feedback about the current status of CIS nodes. Different artificial neural networks (ANNs were created in order to solve the scheduling problem. Their performances were compared and as the main result of this paper, an optimal ANN architecture for workflow scheduling in CISs is proposed. A case study is shown for a meter data management system with measurements from a power distribution management system in Serbia. Performance tests show that significant improvement of the overall execution time can be achieved by ANNs.

  9. Optimal ROS Signaling Is Critical for Nuclear Reprogramming

    Directory of Open Access Journals (Sweden)

    Gang Zhou

    2016-05-01

    Full Text Available Efficient nuclear reprogramming of somatic cells to pluripotency requires activation of innate immunity. Because innate immune activation triggers reactive oxygen species (ROS signaling, we sought to determine whether there was a role of ROS signaling in nuclear reprogramming. We examined ROS production during the reprogramming of doxycycline (dox-inducible mouse embryonic fibroblasts (MEFs carrying the Yamanaka factors (Oct4, Sox2, Klf4, and c-Myc [OSKM] into induced pluripotent stem cells (iPSCs. ROS generation was substantially increased with the onset of reprogramming. Depletion of ROS via antioxidants or Nox inhibitors substantially decreased reprogramming efficiency. Similarly, both knockdown and knockout of p22phox—a critical subunit of the Nox (1–4 complex—decreased reprogramming efficiency. However, excessive ROS generation using genetic and pharmacological approaches also impaired reprogramming. Overall, our data indicate that ROS signaling is activated early with nuclear reprogramming, and optimal levels of ROS signaling are essential to induce pluripotency.

  10. Adaptive Inverse Optimal Control for Rehabilitation Robot Systems Using Actor-Critic Algorithm

    National Research Council Canada - National Science Library

    Meng, Fancheng; Dai, Yaping

    2014-01-01

    ...) combining inverse optimal control and actor-critic learning is proposed. Specifically, an uncertain nonlinear rehabilitation robot model is firstly developed that includes human motor behavior dynamics...

  11. Optimization of solution-processed oligothiophene:fullerene based organic solar cells by using solvent additives

    National Research Council Canada - National Science Library

    Schulz, Gisela L; Urdanpilleta, Marta; Fitzner, Roland; Brier, Eduard; Mena-Osteritz, Elena; Reinold, Egon; Bäuerle, Peter

    2013-01-01

    The optimization of solution-processed organic bulk-heterojunction solar cells with the acceptor-substituted quinquethiophene DCV5T-Bu 4 as donor in conjunction with PC61BM as acceptor is described...

  12. Composition Optimization and Stability Testing of a Parenteral Antifungal Solution based on a Ternary Solvent System

    OpenAIRE

    Kovács, Kristóf; Antal, István; Stampf, György; Klebovich, Imre; Ludányi, Krisztina

    2010-01-01

    An intravenous solution is a dosage forms intended for administration into the bloodstream. This route is the most rapid and the most bioavailable method of getting drugs into systemic circulation, and therefore it is also the most liable to cause adverse effects. In order to reduce the possibility of side effects and to ensure adequate clinical dosage of the formulation, the primarily formulated composition should be optimized. It is also important that the composition should retain its ther...

  13. Optimization of 2-ethylhexyl palmitate production using lipozyme RM IM as catalyst in a solvent-free system.

    Science.gov (United States)

    Richetti, Aline; Leite, Selma G F; Antunes, Octávio A C; de Souza, Andrea L F; Lerin, Lindomar A; Dallago, Rogério M; Paroul, Natalia; Di Luccio, Marco; Oliveira, J Vladimir; Treichel, Helen; de Oliveira, Débora

    2010-04-01

    This work reports the application of a lipase in the 2-ethylhexyl palmitate esterification in a solvent-free system with an immobilized lipase (Lipozyme RM IM). A sequential strategy was used applying two experimental designs to optimize the 2-ethylhexyl palmitate production. An empirical model was then built so as to assess the effects of process variables on the reaction conversion. Afterwards, the operating conditions that optimized 2-ethylhexyl palmitate production were established as being acid/alcohol molar ratio 1:3, temperature of 70 degrees C, stirring rate of 150 rpm, 10 wt.% of enzyme, leading to a reaction conversion as high as 95%. From this point, a kinetic study was carried out evaluating the effect of acid:alcohol molar ratio, the enzyme concentration and the temperature on product conversion. The results obtained in this step permit to verify that an excess of alcohol (acid to alcohol molar ratio of 1:6), relatively low enzyme concentration (10 wt.%) and temperature of 70 degrees C, led to conversions next to 100%.

  14. Optimizing the salt-induced activation of enzymes in organic solvents: Effects of lyophilization time and water content

    Energy Technology Data Exchange (ETDEWEB)

    Ru, M.T.; Reimer, J.A.; Clark, D.S. [Univ. of California, Berkeley, CA (United States). Dept. of Chemical Engineering; Dordick, J.S. [Rensselaer Polytechnic Inst., Troy, NY (United States). Dept. of Chemical Engineering

    1999-04-20

    The addition of simple inorganic salts to aqueous enzyme solutions prior to lyophilization results in a dramatic activation of the dried powder in organic media relative to enzyme with no added salt. Activation of both the serine protease subtilisin Carlsberg and lipase from Mucor javanicus resulting from lyophilization in the presence of KCl was highly sensitive to the lyophilization time and water content of the sample. Specifically, for a preparation containing 98% (w/w) KCl, 1% (w/w) phosphate buffer, and 1% (w/w) enzyme, varying the lyophilization time showed a direct correlation between water content and activity up to an optimum, beyond which the activity decreased with increasing lyophilization time. The catalytic efficiency in hexane varied as much as 13-fold for subtilisin Carlsberg and 11-fold for lipase depending on the lyophilization time. This dependence was apparently a consequence of including the salt, as a similar result was not observed for the enzyme freeze-dried without KCl. In the case of subtilisin Carlsberg, the salt-induced optimum value of k{sub cat}/K{sub m} for transesterification in hexane was over 20,000-fold higher than that for salt-free enzyme, a substantial improvement over the previously reported enhancement of 3750-fold. As was found previously for pure enzyme, the salt-activated enzyme exhibited greatest activity when lyophilized from a solution of pH equal to the pH for optimal activity in water. The active-site content of the lyophilized enzyme samples also depended upon lyophilization time and inclusion of salt, with opposite trends in this dependence observed for the solvents hexane and tetrahydrofuran. Finally, substrate selectivity experiments suggested that mechanism(s) other than selective partitioning of substrate into the enzyme-salt matrix are responsible for salt-induced activation of enzymes in organic solvents.

  15. Identification of Major Flavone C-Glycosides and Their Optimized Extraction from Cymbidium kanran Using Deep Eutectic Solvents

    Directory of Open Access Journals (Sweden)

    Kyung Min Jeong

    2017-11-01

    Full Text Available Cymbidium kanran, an orchid exclusively distributed in Northeast Asia, has been highly valued as a decorative plant and traditional herbal medicine. Here, C. kanran extracts were prepared in 70% aqueous methanol using ultrasound-assisted extraction (UAE and subjected to liquid chromatography-photodiode array detection and ultra-high performance liquid chromatography-quadrupole-time-of-flight-mass spectrometry analysis, which were used for quantitative and qualitative analysis, respectively. It was found that the extracts were rich in flavone C-glycosides including vicenin-2, vicenin-3, schaftoside, vitexin, and isovitexin. Ten deep eutectic solvents (DESs were synthesized by combining choline chloride (hydrogen bond acceptor with various polyols and diols (hydrogen bond donors and were tested as a medium for the efficient production of extracts enriched with potentially bioactive flavone C-glycosides from C. kanran. A DES named ChCl:DPG, composed of choline chloride and dipropylene glycol at a 1:4 molar ratio, exhibited the best extraction yields. Then, the effects of extraction conditions on the extraction efficiency were investigated by response surface methodology. Lower water content in the extraction solvent and longer extraction time during UAE were desirable for higher extraction yields. Under the statistically optimized conditions, in which 100 mg of C. kanran powder were extracted in 0.53 mL of a mixture of ChCl:DPG and water (74:26, w/w for 86 min, a total of 3.441 mg g−1 flavone C-glycosides including 1.933 mg g−1 vicenin-2 was obtained. This total yield was 196%, 131%, and 71% more than those obtained using 100% methanol, water, and 70% methanol, respectively.

  16. Critical solvent properties affecting the particle formation process and characteristics of celecoxib-loaded plga microparticles via spray-drying.

    Science.gov (United States)

    Wan, Feng; Bohr, Adam; Maltesen, Morten Jonas; Bjerregaard, Simon; Foged, Camilla; Rantanen, Jukka; Yang, Mingshi

    2013-04-01

    It is imperative to understand the particle formation mechanisms when designing advanced nano/microparticulate drug delivery systems. We investigated how the solvent power and volatility influence the texture and surface chemistry of celecoxib-loaded poly (lactic-co-glycolic acid) (PLGA) microparticles prepared by spray-drying. Binary mixtures of acetone and methanol at different molar ratios were applied to dissolve celecoxib and PLGA prior to spray-drying. The resulting microparticles were characterized with respect to morphology, texture, surface chemistry, solid state properties and drug release profile. The evaporation profiles of the feed solutions were investigated using thermogravimetric analysis (TGA). Spherical PLGA microparticles were obtained, irrespectively of the solvent composition. The particle size and surface chemistry were highly dependent on the solvent power of the feed solution. An obvious burst release was observed for the microparticles prepared by the feed solutions with the highest amount of poor solvent for PLGA. TGA analysis revealed distinct drying kinetics for the binary mixtures. The particle formation process is mainly governed by the PLGA precipitation rate, which is solvent-dependent, and the migration rate of celecoxib molecules during drying. The texture and surface chemistry of the spray-dried PLGA microparticles can therefore be tailored by adjusting the solvent composition.

  17. Interventional nutrition for the critical care patient: optimal diets.

    Science.gov (United States)

    Michel, K E

    1998-11-01

    The classic goals of nutritional support have been to provide for the patient's ongoing nutritional needs and to preserve endogenous tissues from further catabolism. It is becoming increasingly clear that it also is possible to modulate metabolic and pathologic processes through the use of specific nutrients and metabolites and even the route by which nutrition is provided. This article discusses what is and is not known about the nutritional requirements of critically ill dogs and cats and some of the specific nutrients that are being used to enrich formulas for critically ill patients.

  18. Optimal time-critical scheduling via resource augmentation

    Energy Technology Data Exchange (ETDEWEB)

    Phillips, C.A. [Sandia National Labs., Albuquerque, NM (United States); Stein, C. [Dartmouth College, Hanover, NH (United States). Dept. of Computer Science; Torng, E. [Michigan State Univ., East Lansing, MI (United States). Dept. of Computer Science; Wein, J. [Polytechnic Univ., Brooklyn, NY (United States). Dept. of Computer Science

    1997-04-01

    We consider two fundamental problems in dynamic scheduling: scheduling to meet deadlines in a preemptive multiprocessor setting, and scheduling to provide good response time in a number of scheduling environments. When viewed from the perspective of traditional worst-case analysis, no good on-line algorithms exist for these problems, and for some variants no good off-line algorithms exist unless {Rho} = {Nu}{Rho}. We study these problems using a relaxed notion of competitive analysis, introduced by Kalyanasundaram and Pruhs, in which the on-line algorithm is allowed more resources than the optimal off-line algorithm to which it is compared. Using this approach, we establish that several well-known on-line algorithms, that have poor performance from an absolute worst-case perspective, are optimal for the problems in question when allowed moderately more resources. For the optimization of average flow time, these are the first results of any sort, for any {Nu}{Rho}-hard version of the problem, that indicate that it might be possible to design good approximation algorithms.

  19. Critical solvent properties affecting the particle formation process and characteristics of celecoxib-loaded PLGA microparticles via spray-drying

    DEFF Research Database (Denmark)

    Wan, Feng; Bohr, Adam; Maltesen, Morten Jonas

    2013-01-01

    ) microparticles prepared by spray-drying. METHODS: Binary mixtures of acetone and methanol at different molar ratios were applied to dissolve celecoxib and PLGA prior to spray-drying. The resulting microparticles were characterized with respect to morphology, texture, surface chemistry, solid state properties...... and drug release profile. The evaporation profiles of the feed solutions were investigated using thermogravimetric analysis (TGA). RESULTS: Spherical PLGA microparticles were obtained, irrespectively of the solvent composition. The particle size and surface chemistry were highly dependent on the solvent...... power of the feed solution. An obvious burst release was observed for the microparticles prepared by the feed solutions with the highest amount of poor solvent for PLGA. TGA analysis revealed distinct drying kinetics for the binary mixtures. CONCLUSIONS: The particle formation process is mainly governed...

  20. Kinetics and Optimization of Lipophilic Kojic Acid Derivative Synthesis in Polar Aprotic Solvent Using Lipozyme RMIM and Its Rheological Study

    Directory of Open Access Journals (Sweden)

    Nurazwa Ishak

    2018-02-01

    Full Text Available The synthesis of kojic acid derivative (KAD from kojic and palmitic acid (C16:0 in the presence of immobilized lipase from Rhizomucor miehei (commercially known as Lipozyme RMIM, was studied using a shake flask system. Kojic acid is a polyfunctional heterocycles that acts as a source of nucleophile in this reaction allowing the formation of a lipophilic KAD. In this study, the source of biocatalyst, Lipozyme RMIM, was derived from the lipase of Rhizomucor miehei immobilized on weak anion exchange macro-porous Duolite ES 562 by the adsorption technique. The effects of solvents, enzyme loading, reaction temperature, and substrate molar ratio on the reaction rate were investigated. In one-factor-at-a-time (OFAT experiments, a high reaction rate (30.6 × 10−3 M·min−1 of KAD synthesis was recorded using acetone, enzyme loading of 1.25% (w/v, reaction time of 12 h, temperature of 50 °C and substrate molar ratio of 5:1. Thereafter, a yield of KAD synthesis was optimized via the response surface methodology (RSM whereby the optimized molar ratio (fatty acid: kojic acid, enzyme loading, reaction temperature and reaction time were 6.74, 1.97% (w/v, 45.9 °C, and 20 h respectively, giving a high yield of KAD (64.47%. This condition was reevaluated in a 0.5 L stirred tank reactor (STR where the agitation effects of two impellers; Rushton turbine (RT and pitch-blade turbine (PBT, were investigated. In the STR, a very high yield of KAD synthesis (84.12% was achieved using RT at 250 rpm, which was higher than the shake flask, thus indicating better mixing quality in STR. In a rheological study, a pseudoplastic behavior of KAD mixture was proposed for potential application in lotion formulation.

  1. Kinetics and Optimization of Lipophilic Kojic Acid Derivative Synthesis in Polar Aprotic Solvent Using Lipozyme RMIM and Its Rheological Study.

    Science.gov (United States)

    Ishak, Nurazwa; Lajis, Ahmad Firdaus B; Mohamad, Rosfarizan; Ariff, Arbakariya B; Mohamed, Mohd Shamzi; Halim, Murni; Wasoh, Helmi

    2018-02-24

    The synthesis of kojic acid derivative (KAD) from kojic and palmitic acid (C16:0) in the presence of immobilized lipase from Rhizomucor miehei (commercially known as Lipozyme RMIM), was studied using a shake flask system. Kojic acid is a polyfunctional heterocycles that acts as a source of nucleophile in this reaction allowing the formation of a lipophilic KAD. In this study, the source of biocatalyst, Lipozyme RMIM, was derived from the lipase of Rhizomucor miehei immobilized on weak anion exchange macro-porous Duolite ES 562 by the adsorption technique. The effects of solvents, enzyme loading, reaction temperature, and substrate molar ratio on the reaction rate were investigated. In one-factor-at-a-time (OFAT) experiments, a high reaction rate (30.6 × 10 -3 M·min -1 ) of KAD synthesis was recorded using acetone, enzyme loading of 1.25% ( w / v ), reaction time of 12 h, temperature of 50 °C and substrate molar ratio of 5:1. Thereafter, a yield of KAD synthesis was optimized via the response surface methodology (RSM) whereby the optimized molar ratio (fatty acid: kojic acid), enzyme loading, reaction temperature and reaction time were 6.74, 1.97% ( w / v ), 45.9 °C, and 20 h respectively, giving a high yield of KAD (64.47%). This condition was reevaluated in a 0.5 L stirred tank reactor (STR) where the agitation effects of two impellers; Rushton turbine (RT) and pitch-blade turbine (PBT), were investigated. In the STR, a very high yield of KAD synthesis (84.12%) was achieved using RT at 250 rpm, which was higher than the shake flask, thus indicating better mixing quality in STR. In a rheological study, a pseudoplastic behavior of KAD mixture was proposed for potential application in lotion formulation.

  2. The Optimal Dose of Midazolam for Promoting Sleep in Critically Ill Patients: A Pilot Study

    OpenAIRE

    Se Joong Kim; Jisoo Park; Yeon Joo Lee; Jong Sun Park; Ho Il Yoon; Jae Ho Lee; Choon Taek Lee; Young Jae Cho

    2014-01-01

    BACKGROUND: Many critically ill patients treated in the intensive care unit (ICU) experience sleep disruption. Midazolam is commonly used for the sedation of critically ill patients. This pilot study is aimed to identify the optimal dose of midazolam for achieving sound sleep in critically ill patients. METHODS: This prospective study was conducted in the medical ICU of a tertiary referral hospital. Polysomnography recording was performed over 24 hours to assess the quantity and quality...

  3. In silico optimization of critical currents in superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Kimmel, Gregory; Sadovskyy, Ivan A.; Glatz, Andreas

    2017-07-01

    For many technological applications of superconductors the performance of a material is determined by the highest current it can carry losslessly-the critical current. In turn, the critical current can be controlled by adding nonsuperconducting defects in the superconductor matrix. Here we report on systematic comparison of different local and global optimization strategies to predict optimal structures of pinning centers leading to the highest possible critical currents. We demonstrate performance of these methods for a superconductor with randomly placed spherical, elliptical, and columnar defects.

  4. Optimization of oil yield from Hevea brasiliensis seeds through ultrasonic-assisted solvent extraction via response surface methodology

    Directory of Open Access Journals (Sweden)

    Val Irvin F. Mabayo

    2018-01-01

    Full Text Available The demand for oil has been increasing vastly over time, and the source of this has slowly been diminishing. The use of non-food feedstock is seen as a promising alternative source for the production of bio-based fuel. In this study, rubber (Hevea brasiliensis seeds were utilized as biomass in bio-oil production considering that these are non-edible and considered wastes in rubber tree plantations. In the oil extraction process, the rubber seed kernels were oven dried at 100 °C for 24 h, powdered and then dried further at 105 °C for 4 h. After characterization, optimization study was done using Design Expert 7.0 software through central composite design of the response surface methodology. Ultrasonication technology was employed in the oil extraction process which significantly reduced the reaction time needed for extraction to 15 min compared the conventional extraction method of at least 8 h. An optimum rubber seed oil (RSO yield of 30.3 ± 0.3% was obtained using 15 g biomass, 5:1 n-hexane to biomass (mL g−1 ratio, 50 μm resonance amplitude and 60 ± 5 °C temperature at 15 min reaction time. The oil yield at optimum condition was found to have 0.89 g mL−1 density at room temperature, 26.7 cSt kinematic viscosity at 40 °C and high heating value of 39.2 MJ kg−1. The Fourier Transform Infrared Radiation spectroscopy analysis of the RSO, at optimum condition, showed the presence of carboxylic acid and ester carbonyl functional groups which are good indicators as a potential source of biodiesel. Keywords: Hevea brasiliensis, Oil extraction, Optimization, Response surface methodology, Rubber seed oil, Ultrasonic-assisted solvent extraction

  5. Solvents and solvent effects in organic chemistry

    National Research Council Canada - National Science Library

    Reichardt, C; Welton, T

    2011-01-01

    ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Solute-Solvent Interactions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Solutions...

  6. Multiple actor-critic structures for continuous-time optimal control using input-output data.

    Science.gov (United States)

    Song, Ruizhuo; Lewis, Frank; Wei, Qinglai; Zhang, Hua-Guang; Jiang, Zhong-Ping; Levine, Dan

    2015-04-01

    In industrial process control, there may be multiple performance objectives, depending on salient features of the input-output data. Aiming at this situation, this paper proposes multiple actor-critic structures to obtain the optimal control via input-output data for unknown nonlinear systems. The shunting inhibitory artificial neural network (SIANN) is used to classify the input-output data into one of several categories. Different performance measure functions may be defined for disparate categories. The approximate dynamic programming algorithm, which contains model module, critic network, and action network, is used to establish the optimal control in each category. A recurrent neural network (RNN) model is used to reconstruct the unknown system dynamics using input-output data. NNs are used to approximate the critic and action networks, respectively. It is proven that the model error and the closed unknown system are uniformly ultimately bounded. Simulation results demonstrate the performance of the proposed optimal control scheme for the unknown nonlinear system.

  7. Choline chloride (ChCl) and monosodium glutamate (MSG)-based green solvents from optimized cactus malic acid for biomass delignification.

    Science.gov (United States)

    Yiin, Chung Loong; Quitain, Armando T; Yusup, Suzana; Uemura, Yoshimitsu; Sasaki, Mitsuru; Kida, Tetsuya

    2017-11-01

    This work aimed to develop an efficient microwave-hydrothermal (MH) extraction of malic acid from abundant natural cactus as hydrogen bond donor (HBD) whereby the concentration was optimized using response surface methodology. The ideal process conditions were found to be at a solvent-to-feed ratio of 0.008, 120°C and 20min with 1.0g of oxidant, H2O2. Next generation environment-friendly solvents, low transition temperature mixtures (LTTMs) were synthesized from cactus malic acid with choline chloride (ChCl) and monosodium glutamate (MSG) as hydrogen bond acceptors (HBAs). The hydrogen-bonding interactions between the starting materials were determined. The efficiency of the LTTMs in removing lignin from oil palm biomass residues, empty fruit bunch (EFB) was also evaluated. The removal of amorphous hemicellulose and lignin after the pretreatment process resulted in an enhanced digestibility and thermal degradability of biomass. Copyright © 2017 Elsevier Ltd. All rights reserved.

  8. The hybrid MPC-MINLP algorithm for optimal operation of coal-fired power plants with solvent based post-combustion CO2 capture

    Directory of Open Access Journals (Sweden)

    Norhuda Abdul Manaf

    2017-03-01

    Full Text Available This paper presents an algorithm that combines model predictive control (MPC with MINLP optimization and demonstrates its application for coal-fired power plants retrofitted with solvent based post-combustion CO2 capture (PCC plant. The objective function of the optimization algorithm works at a primary level to maximize plant economic revenue while considering an optimal carbon capture profile. At a secondary level, the MPC algorithm is used to control the performance of the PCC plant. Two techno-economic scenarios based on fixed (capture rate is constant and flexible (capture rate is variable operation modes are developed using actual electricity prices (2011 with fixed carbon prices ($AUD 5, 25, 50/tonne-CO2 for 24 h periods. Results show that fixed operation mode can bring about a ratio of net operating revenue deficit at an average of 6% against the superior flexible operation mode.

  9. Optimizing gradient conditions in online comprehensive two-dimensional reversed-phase liquid chromatography by use of the linear solvent strength model

    DEFF Research Database (Denmark)

    Græsbøll, Rune; Janssen, Hans-Gerd; Christensen, Jan H.

    2017-01-01

    The linear solvent strength model was used to predict coverage in online comprehensive two-dimensional reversed-phase liquid chromatography. The prediction model uses a parallelogram to describe the separation space covered with peaks in a system with limited orthogonality. The corners...... factors were low, or when gradient conditions affected parameters not included in the model, e.g. second dimension gradient time affects the second dimension equilibration time. The concept shows promise as a tool for gradient optimization in online comprehensive two-dimensional liquid chromatography......, as it mitigates the tedious registration and modeling of all sample constituents, a circumstance that is particularly appealing when dealing with complex samples....

  10. Sub-critical water as a green solvent for production of valuable materials from agricultural waste biomass: A review of recent work

    Directory of Open Access Journals (Sweden)

    A. Shitu

    2015-07-01

    Full Text Available Agricultural waste biomass generated from agricultural production and food processing industry are abundant, such as durian  peel, mango peel, corn straw, rice bran, corn shell, potato peel and many more. Due to low commercial value, these wastes are disposed in landfill, which if not managed properly may cause environmental problems. Currently, environmental laws and regulations pertaining to the pollution from agricultural waste streams by regulatory agencies are stringent and hence the application of toxic solvents during processing has become public concern. Recent development in valuable materials extraction from the decomposition of agricultural waste by sub-critical water treatment from the published literature was review. Physico-chemical characteristic (reaction temperature, reaction time and solid to liquid ratio of the sub-critical water affecting its yield were also reviewed. The utilization of biomass residue from agriculture, forest wood production and from food and feed processing industry may be an important alternative renewable energy supply. The paper also presents future research on sub-critical water.

  11. Effect of extraction solvents on the biomolecules and antioxidant properties of Scorzonera undulata (Asteraceae): Application of factorial design optimization phenolic extraction.

    Science.gov (United States)

    Athmouni, Khaled; Belghith, Taheni; Bellassouad, Khaled; Feki, Abdelfattah El; Ayadi, Habib

    2015-01-01

    Phenolic compounds were extracted and isolated from S. undulata roots. Sample of roots from E. hirta was tested for phenolic compounds, and in vitro antioxidant activity by diphenyl-1-picrylhydrazyl (DPPH) assay, ABTS, FRAP and reducing power was measured using cyano- ferrate method. The methanolic fraction exhibited the highest total phenol content (6.12 ±0.11 mg AGE/g DW). On the other hand, the highest flavonoids concentration was observed in ethyl acetate fraction (2.90 ±0.05 mg CE/g DW) in addition to anthocyanins (28.56 ±3.96 mg/l). Besides, the highest level of tannins content was measured in the polar aprotic solvent ethyl acetate extract (3.25 ±0.06 mg CE/g DW). The different extracts of S. undulata were evaluated for their radical scavenging activities by means of the DPPH assay. The strongest scavenging activity was observed in methanolic fraction scavenged radicals effectively with IC   values of 0.14 ±0.02 mg/ml. Similarly, the potassium ferricyanide reduction (FRAP) and ABTS•+ of methanol extract. On the other hand, the total reducing power of ethyl acetate extract was found higher than of other extracts. This paper presents the application of the design-of experiment method for optimizing the extraction of phenolic content using methanol solvent. The resulting regression model has shown that the effect of temperature is not statistically significant (with >95% certainty), while that of agitation speed is. The two main effects are contributed by the solvent concentration and the maceration period. Our results clearly showed that the extraction of phenolic compounds and their antioxidant capacity is significantly affected by solvent combinations. S. undulata presented the highest total phenolic content, total flavonoids content and antioxidant capacity values. The resulting regression model has shown that the effect of temperature is not statistically significant (with >95% certainty), while that of agitation speed is.

  12. Design Optimization of Mixed-Criticality Real-Time Embedded Systems

    DEFF Research Database (Denmark)

    Tamas-Selicean, Domitian; Pop, Paul

    2015-01-01

    In this article, we are interested in implementing mixed-criticality real-time embedded applications on a given heterogeneous distributed architecture. Applications have different criticality levels, captured by their Safety-Integrity Level (SIL), and are scheduled using static-cyclic scheduling....... tables, such that all the applications are schedulable and the development costs are minimized. We have proposed a Tabu Search-based approach to solve this optimization problem. The proposed algorithm has been evaluated using several synthetic and real-life benchmarks....

  13. Parametric Optimization of Some Critical Operating System Functions--An Alternative Approach to the Study of Operating Systems Design

    Science.gov (United States)

    Sobh, Tarek M.; Tibrewal, Abhilasha

    2006-01-01

    Operating systems theory primarily concentrates on the optimal use of computing resources. This paper presents an alternative approach to teaching and studying operating systems design and concepts by way of parametrically optimizing critical operating system functions. Detailed examples of two critical operating systems functions using the…

  14. Actor-critic-based optimal tracking for partially unknown nonlinear discrete-time systems.

    Science.gov (United States)

    Kiumarsi, Bahare; Lewis, Frank L

    2015-01-01

    This paper presents a partially model-free adaptive optimal control solution to the deterministic nonlinear discrete-time (DT) tracking control problem in the presence of input constraints. The tracking error dynamics and reference trajectory dynamics are first combined to form an augmented system. Then, a new discounted performance function based on the augmented system is presented for the optimal nonlinear tracking problem. In contrast to the standard solution, which finds the feedforward and feedback terms of the control input separately, the minimization of the proposed discounted performance function gives both feedback and feedforward parts of the control input simultaneously. This enables us to encode the input constraints into the optimization problem using a nonquadratic performance function. The DT tracking Bellman equation and tracking Hamilton-Jacobi-Bellman (HJB) are derived. An actor-critic-based reinforcement learning algorithm is used to learn the solution to the tracking HJB equation online without requiring knowledge of the system drift dynamics. That is, two neural networks (NNs), namely, actor NN and critic NN, are tuned online and simultaneously to generate the optimal bounded control policy. A simulation example is given to show the effectiveness of the proposed method.

  15. Design Optimization of Mixed-Criticality Real-Time Applications on Cost-Constrained Partitioned Architectures

    DEFF Research Database (Denmark)

    Tamas-Selicean, Domitian; Pop, Paul

    2011-01-01

    In this paper we are interested to implement mixed-criticality hard real-time applications on a given heterogeneous distributed architecture. Applications have different criticality levels, captured by their Safety-Integrity Level (SIL), and are scheduled using static-cyclic scheduling. Mixed......-criticality tasks can be integrated onto the same architecture only if there is enough spatial and temporal separation among them. We consider that the separation is provided by partitioning, such that applications run in separate partitions, and each partition is allocated several time slots on a processor. Tasks...... slots on each processor and (iv) the schedule tables, such that all the applications are schedulable and the development costs are minimized. We have proposed a Tabu Search-based approach to solve this optimization problem. The proposed algorithm has been evaluated using several synthetic and real...

  16. Enhanced low-temperature NH3-SCR performance of MnOx/CeO2 catalysts by optimal solvent effect

    Science.gov (United States)

    Yao, Xiaojiang; Kong, Tingting; Chen, Li; Ding, Shimin; Yang, Fumo; Dong, Lin

    2017-10-01

    A series of MnOx/CeO2 catalysts were prepared by modulating the solvents (deionized water (DW), anhydrous ethanol (AE), acetic acid (AA), and oxalic acid (OA) solution) with the purpose of improving the low-temperature NH3-SCR performance, broadening the operating temperature window, and enhancing the H2O + SO2 resistance. The synthesized catalysts were characterized by means of N2-physisorption, XRD, EDS mapping, Raman, XPS, H2-TPR, NH3-TPD, and in situ DRIFTS technologies. Furthermore, the catalytic performance and H2O + SO2 resistance were evaluated by NH3-SCR model reaction. The obtained results indicate that MnOx/CeO2 catalyst prepared with oxalic acid solution as a solvent exhibits the best catalytic performance among these catalysts, which shows above 80% NO conversion during a wide operating temperature range of 100-250 °C and good H2O + SO2 resistance for low-temperature NH3-SCR reaction. This is related to that oxalic acid solution can promote the dispersion of MnOx and enhance the electron interaction between MnOx and CeO2, which are beneficial to improving the physicochemical property of MnOx/CeO2 catalyst, and further lead to the enhancement of catalytic performance and good H2O + SO2 resistance.

  17. Design of optimal solvent for extraction of bio–active ingredients from six varieties of Medicago sativa

    Directory of Open Access Journals (Sweden)

    Caunii Angela

    2012-10-01

    Full Text Available Abstract Background Extensive research has been performed worldwide and important evidences were collected to show the immense potential of plants used in various traditional therapeutic systems. The aim of this work is to investigate the different extracting solvents in terms of the influence of their polarity on the extracting ability of bioactive molecules (phenolic compounds from the M. sativa flowers. Results The total phenolic content of samples was determined using the Folin Ciocalteu (FC procedure and their antioxidant activity was assayed through in vitro radical decomposing activity using the radical DPPH° assay (IUPAC name for DPPH is (phenyl–(2,4,6–trinitrophenyl iminoazanium. The results showed that water was better than methanol and acetic acid for extracting bioactive compounds, in particular for total phenolic compounds from the flowers of alfalfa. The average content of bioactive molecules in methanol extract was 263.5±1.02 mg GAE/100g of dry weight lyophilized extract. The total phenolic content of the tested plant extracts was highly correlated with the radical decomposing activity. However, all extracts were free–radical inhibitors, but the water extract was more potent than the acetic and the methanol ones. The order of inhibitor effectiveness (expressed by IC50 proved to be: water extract (0.924mg/mL > acetic acid extract (0.154mg/mL > methanol (0.079mg/mL. The profiles of each extract (fingerprint were characterized by FT–MIR spectroscopy. Conclusions The present study compares the fingerprint of different extracts of the M. sativa flowers, collected from the wild flora of Romania. The total phenolic content of the tested plant extracts was highly correlated with the radical decomposing activity. The dependence of the extract composition on the solvent polarity (acetic acid vs. methanol vs. water was revealed by UV–VIS spectrometry and Infrared fingerprint.

  18. Solvent selection and optimization of α-chymotrypsin-catalyzed synthesis of N-Ac-Phe-Tyr-NH2 using mixture design and response surface methodology.

    Science.gov (United States)

    Hu, Shih-Hao; Kuo, Chia-Hung; Chang, Chieh-Ming J; Liu, Yung-Chuan; Chiang, Wen-Dee; Shieh, Chwen-Jen

    2012-01-01

    A peptide, N-Ac-Phe-Tyr-NH(2) , with angiotensin I-converting enzyme (ACE) inhibitor activity was synthesized by an α-chymotrypsin-catalyzed condensation reaction of N-acetyl phenylalanine ethyl ester (N-Ac-Phe-OEt) and tyrosinamide (Tyr-NH(2) ). Three kinds of solvents: a Tris-HCl buffer (80 mM, pH 9.0), dimethylsulfoxide (DMSO), and acetonitrile were employed in this study. The optimum reaction solvent component was determined by simplex centroid mixture design. The synthesis efficiency was enhanced in an organic-aqueous solvent (Tris-HCl buffer: DMSO: acetonitrile = 2:1:1) in which 73.55% of the yield of N-Ac-Phe-Tyr-NH(2) could be achieved. Furthermore, the effect of reaction parameters on the yield was evaluated by response surface methodology (RSM) using a central composite rotatable design (CCRD). Based on a ridge max analysis, the optimum condition for this peptide synthesis included a reaction time of 7.4 min, a reaction temperature of 28.1°C, an enzyme activity of 98.9 U, and a substrate molar ratio (Phe:Tyr) of 1:2.8. The predicted and the actual (experimental) yields were 87.6 and 85.5%, respectively. The experimental design and RSM performed well in the optimization of synthesis of N-Ac-Phe-Tyr-NH(2) , so it is expected to be an effective method for obtaining a good yield of enzymatic peptide. © 2012 American Institute of Chemical Engineers Biotechnol. Prog., 2012. Copyright © 2012 American Institute of Chemical Engineers (AIChE).

  19. Optimizing mission critical data dissemination in massive IoT networks

    KAUST Repository

    Farooq, Muhammad Junaid

    2017-06-29

    Mission critical data dissemination in massive Internet of things (IoT) networks imposes constraints on the message transfer delay between devices. Due to low power and communication range of IoT devices, data is foreseen to be relayed over multiple device-to-device (D2D) links before reaching the destination. The coexistence of a massive number of IoT devices poses a challenge in maximizing the successful transmission capacity of the overall network alongside reducing the multi-hop transmission delay in order to support mission critical applications. There is a delicate interplay between the carrier sensing threshold of the contention based medium access protocol and the choice of packet forwarding strategy selected at each hop by the devices. The fundamental problem in optimizing the performance of such networks is to balance the tradeoff between conflicting performance objectives such as the spatial frequency reuse, transmission quality, and packet progress towards the destination. In this paper, we use a stochastic geometry approach to quantify the performance of multi-hop massive IoT networks in terms of the spatial frequency reuse and the transmission quality under different packet forwarding schemes. We also develop a comprehensive performance metric that can be used to optimize the system to achieve the best performance. The results can be used to select the best forwarding scheme and tune the carrier sensing threshold to optimize the performance of the network according to the delay constraints and transmission quality requirements.

  20. Proteins and amino acids are fundamental to optimal nutrition support in critically ill patients.

    Science.gov (United States)

    Weijs, Peter J M; Cynober, Luc; DeLegge, Mark; Kreymann, Georg; Wernerman, Jan; Wolfe, Robert R

    2014-11-17

    Proteins and amino acids are widely considered to be subcomponents in nutritional support. However, proteins and amino acids are fundamental to recovery and survival, not only for their ability to preserve active tissue (protein) mass but also for a variety of other functions. Understanding the optimal amount of protein intake during nutritional support is therefore fundamental to appropriate clinical care. Although the body adapts in some ways to starvation, metabolic stress in patients causes increased protein turnover and loss of lean body mass. In this review, we present the growing scientific evidence showing the importance of protein and amino acid provision in nutritional support and their impact on preservation of muscle mass and patient outcomes. Studies identifying optimal dosing for proteins and amino acids are not currently available. We discuss the challenges physicians face in administering the optimal amount of protein and amino acids. We present protein-related nutrition concepts, including adaptation to starvation and stress, anabolic resistance, and potential adverse effects of amino acid provision. We describe the methods for assessment of protein status, and outcomes related to protein nutritional support for critically ill patients. The identification of a protein target for individual critically ill patients is crucial for outcomes, particularly for specific subpopulations, such as obese and older patients. Additional research is urgently needed to address these issues.

  1. [Optimal energy supply in different age groups of critically ill children on mechanical ventilation].

    Science.gov (United States)

    Li, X H; Ji, J; Qian, S Y

    2018-01-02

    Objective: To analyze the resting energy expenditure and optimal energy supply in different age groups of critically ill children on mechanical ventilation in pediatric intensive care unit (PICU). Methods: Patients on mechanical ventilation hospitalized in PICU of Beijing Children's Hospital from March 2015 to March 2016 were enrolled prospectively. Resting energy expenditure of patients was calculated by US Med Graphic company critical care management (CCM) energy metabolism test system after mechanical ventilation. Patients were divided into three groups:10 years. The relationship between the measured and predictive resting energy expenditure was analyzed with correlation analysis; while the metabolism status and the optimal energy supply in different age groups were analyzed with chi square test and variance analysis. Results: A total of 102 patients were enrolled, the measured resting energy expenditure all correlated with predictive resting energy expenditure in different age groups (10 years ( r= 0.5, P= 0.0) ) . A total of 40 cases in 10 years group, including: 12 cases of low metabolism (71%), 4 cases of normal metabolism (23%), 1 case of high metabolism (6%). Metabolism status showed significant differences between different age groups ( χ (2)=11.30, P energy requirement was (210±84) kJ/ (kg⋅d) . There were significant differences in actual energy requirement between age groups ( F= 46.57, P 10 years group. Conclusion: The resting energy metabolism of the critically ill children on mechanical ventilation is negatively related to the age. The actual energy requirement should be calculated according to different ages.

  2. SWANS: A Prototypic SCALE Criticality Sequence for Automated Optimization Using the SWAN Methodology

    Energy Technology Data Exchange (ETDEWEB)

    Greenspan, E.

    2001-01-11

    SWANS is a new prototypic analysis sequence that provides an intelligent, semi-automatic search for the maximum k{sub eff} of a given amount of specified fissile material, or of the minimum critical mass. It combines the optimization strategy of the SWAN code with the composition-dependent resonance self-shielded cross sections of the SCALE package. For a given system composition arrived at during the iterative optimization process, the value of k{sub eff} is as accurate and reliable as obtained using the CSAS1X Sequence of SCALE-4.4. This report describes how SWAN is integrated within the SCALE system to form the new prototypic optimization sequence, describes the optimization procedure, provides a user guide for SWANS, and illustrates its application to five different types of problems. In addition, the report illustrates that resonance self-shielding might have a significant effect on the maximum k{sub eff} value a given fissile material mass can have.

  3. Solvent-free enzymatic synthesis of 1,3-diconjugated Linoleoyl Glycerol Optimized by Response Surface Methodology

    DEFF Research Database (Denmark)

    Guo, Zheng; Sun, Yan

    2004-01-01

    An operation mode with N2 bubbling under vacuum was employed for the solventfree synthesis of 1,3-diconjugated linoleoyl glycerol (1,3-dCLG) from conjugated linoleic acid (CLA) catalyzed by Novozym 435. The response surface methodology (RSM) was adopted for the optimization of the reaction...... between the experimental and the predicted values of 1,3- dCLG yield. Under the optimal conditions, the yield of 1,3-dCLG up to 93% was obtained. The reaction was scaled up to a production level of 100 g of 1,3-dCLG at a yield of 90.7%, indicating a promising feature of the technology in industrial...

  4. Measurement of the main and critical parameters for optimal laser treatment of heart disease

    Science.gov (United States)

    Kabeya, FB; Abrahamse, H.; Karsten, AE

    2017-10-01

    Laser light is frequently used in the diagnosis and treatment of patients. As in traditional treatments such as medication, bypass surgery, and minimally invasive ways, laser treatment can also fail and present serious side effects. The true reason for laser treatment failure or the side effects thereof, remains unknown. From the literature review conducted, and experimental results generated we conclude that an optimal laser treatment for coronary artery disease (named heart disease) can be obtained if certain critical parameters are correctly measured and understood. These parameters include the laser power, the laser beam profile, the fluence rate, the treatment time, as well as the absorption and scattering coefficients of the target treatment tissue. Therefore, this paper proposes different, accurate methods for the measurement of these critical parameters to determine the optimal laser treatment of heart disease with a minimal risk of side effects. The results from the measurement of absorption and scattering properties can be used in a computer simulation package to predict the fluence rate. The computing technique is a program based on the random number (Monte Carlo) process and probability statistics to track the propagation of photons through a biological tissue.

  5. Solvent substitution

    Energy Technology Data Exchange (ETDEWEB)

    1990-01-01

    The DOE Environmental Restoration and Waste Management Office of Technology Development and the Air Force Engineering and Services Center convened the First Annual International Workshop on Solvent Substitution on December 4--7, 1990. The primary objectives of this joint effort were to share information and ideas among attendees in order to enhance the development and implementation of required new technologies for the elimination of pollutants associated with industrial use of hazardous and toxic solvents; and to aid in accelerating collaborative efforts and technology transfer between government and industry for solvent substitution. There were workshop sessions focusing on Alternative Technologies, Alternative Solvents, Recovery/Recycling, Low VOC Materials and Treatment for Environmentally Safe Disposal. The 35 invited papers presented covered a wide range of solvent substitution activities including: hardware and weapons production and maintenance, paint stripping, coating applications, printed circuit boards, metal cleaning, metal finishing, manufacturing, compliance monitoring and process control monitoring. This publication includes the majority of these presentations. In addition, in order to further facilitate information exchange and technology transfer, the US Air Force and DOE solicited additional papers under a general Call for Papers.'' These papers, which underwent review and final selection by a peer review committee, are also included in this combined Proceedings/Compendium. For those involved in handling, using or managing hazardous and toxic solvents, this document should prove to be a valuable resource, providing the most up-to-date information on current technologies and practices in solvent substitution. Individual papers are abstracted separated.

  6. Optimization of a Dry, Mixed Nuclear Fuel Storage Array for Nuclear Criticality Safety

    Science.gov (United States)

    Baranko, Benjamin T.

    A dry storage array of used nuclear fuel at the Idaho National Laboratory contains a mixture of more than twenty different research and test reactor fuel types in up to 636 fuel storage canisters. New analysis demonstrates that the current arrangement of the different fuel-type canisters does not minimize the system neutron multiplication factor (keff), and that the entire facility storage capacity cannot be utilized without exceeding the subcritical limit (ksafe) for ensuring nuclear criticality safety. This work determines a more optimal arrangement of the stored fuels with a goal to minimize the system keff, but with a minimum of potential fuel canister relocation movements. The solution to this multiple-objective optimization problem will allow for both an improvement in the facility utilization while also offering an enhancement in the safety margin. The solution method applies stochastic approximation and a Tabu search metaheuristic to an empirical model developed from supporting MCNP calculations. The results establish an optimal relocation of between four to sixty canisters, which will allow the current thirty-one empty canisters to be used for storage while reducing the array keff by up to 0.018 +/- 0.003 relative to the current arrangement.

  7. [Selection and optimal sequence of critical elements for medication review: A simulation with hospital pharmacy residents].

    Science.gov (United States)

    Dubois, S; Barbier, A; Thibault, M; Atkinson, S; Bussières, J-F

    2017-03-01

    The main objective of this study was to compare the responses of pharmacy residents regarding critical steps for medication order review, in the presence or absence of clinical pharmacists on patient care units, to describe the sequence of these steps and to compare them to an optimal sequence. The secondary objectives were to test this sequence in a simulation and to assess the residents' level of agreement on medication order review. Twenty-two validation steps were selected from guidelines. A simulation on order review was organized in three steps: selecting elements judged to be necessary or not for the order review critical path, then organizing this sequence in chronological order, implementation of this critical path on two simulated practical cases, resident perceptions about order review in their training. Forty-one residents participated in the activity. Responses were heterogeneous regarding the elements' sequence and the time required for the review of a simulated case (3-13minutes). A majority of residents considered that their training was insufficient (29/41), that pharmacists validated differently (27/41), and that it was impossible to review the 22 proposed items for each prescription (30/41). This article highlights heterogeneous medication order review practices among pharmacy residents, due to a lack of training in their curriculum according to them. It is essential to acquire medication order review standard both locally and nationally. Copyright © 2016 Académie Nationale de Pharmacie. Published by Elsevier Masson SAS. All rights reserved.

  8. Care of the Critically Ill Burn Patient. An Overview from the Perspective of Optimizing Palliative Care.

    Science.gov (United States)

    Ray, Daniel E; Karlekar, Mohana B; Crouse, Donnelle L; Campbell, Margaret; Curtis, J Randall; Edwards, Jeffrey; Frontera, Jennifer; Lustbader, Dana R; Mosenthal, Anne C; Mulkerin, Colleen; Puntillo, Kathleen A; Weissman, David E; Boss, Renee D; Brasel, Karen J; Nelson, Judith E

    2017-07-01

    Burn specialists have long recognized the need for and have role modeled a comprehensive approach incorporating relief of distress as part of care during critical illness. More recently, palliative care specialists have become part of the healthcare team in many U.S. hospitals, especially larger academic institutions that are more likely to have designated burn centers. No current literature describes the intersection of palliative care and burn care or integration of primary and specialist palliative care in this unique context. This Perspective gives an overview of burn care; focuses on pain and other symptoms in burn intensive care unit settings; addresses special needs of critically ill burned patients, their families, and clinicians for high-quality palliative care; and highlights potential benefits of integrating primary and specialist palliative care in burn critical care. MEDLINE and the Cumulative Index to Nursing and Allied Health Literature were searched, and an e-mail survey was used to obtain information from U.S. Burn Fellowship Program directors about palliative medicine training. The Improving Palliative Care in the Intensive Care Unit Project Advisory Board synthesized published evidence with their own research and clinical experience in preparing this article. Mortality and severe morbidity for critically ill burned patients remains high. American Burn Association guidelines lay the foundation for a robust system of palliative care delivery, embedding palliative care principles and processes in intensive care by burn providers. Understanding basic burn care, challenges for symptom management and communication, and the culture of the particular burn unit, can optimize quality and integration of primary and specialist palliative care in this distinctive setting.

  9. Dual response surface-optimized process for feruloylated diacylglycerols by selective lipase-catalyzed transesterification in solvent free system.

    Science.gov (United States)

    Zheng, Yan; Wu, Xiao-Mei; Branford-White, Christopher; Quan, Jing; Zhu, Li-Min

    2009-06-01

    Feruloylated diacylglycerol (FDAG) was synthesized using a selective lipase-catalyzed the transesterification between ethyl ferulate and triolein. To optimize the reaction conversion and purity of FDAG, dual response surface was applied to determine the effects of five-level-five-factors and their reciprocal interactions on product synthesis. A total of 32 individual experiments were performed to study reaction temperature, reaction time, substrate molar ratio, enzyme loading, and water activity. The highest reaction conversion and selectivity towards FDAG were 73.9% and 92.3%, respectively, at 55 degrees C, reaction time 5.3 day, enzyme loading 30.4 mg/ml, water activity 0.08, and a substrate molar ratio of 3.7. Moreover, predicted values showed good validation with the experimental values when experiments corresponding to selected points on the contour plots were carried out.

  10. Optimization of dairy based farming agricultural in critical land area of Yogyakarta Special Territory

    Directory of Open Access Journals (Sweden)

    Elan Masbula

    1999-12-01

    Full Text Available A study has been done to provide a conceptual basis for the development of agricultural system in critical land area in Yogyakarta Special Teritory as the smallest production unit to (1 determine optimum dairy farming based agriculture for the area and income maximization on either farmer own inputs or with CAFlTAL aid provided by a funding party, (2 to develop a model for developing farming system based on dairy farming in critical land area in Yogyakarta Special Teritory.Methods being used multistage problem solving approach to the problem encountered in farming system as practiced in Glagaharjo Village, Sub District of Cangkringan, Sleman with Rapid Rural Appraisal (RRA and Agro-ecosystem Analysis as diagnostic activities. Farm record keeping and survey to fourty respondents purposively selected were then conducted. Using Linear Programming (LPM, a normative solution, under the imposed constraints for each activity, was obtained to see development effectivity of dairy based farming agricultural system. The result indicated that land resources had not managed optimally. Out of an average possession of 1,5 ha dry land, only 0,6 ha was cultivated, leading to relativelly low yield and income. Optimum dairy farming agriculture migh be an option to develop the area. Dairy farm Cooperative Agency (Model of Scenario I can play important role to improve farmer income. With an average of 1,5 ha dry land and an average of 3 Animal Unit raised would optimized the resources allocation and income of Rp.20,385,340 for a period of eight years. The income rnigh be further increased to Rp.36,176,070 for similar production period with soft loan provided by ventura fund (Model of Scenario ll to optimize land resources and family labor force use and a farmer was able to raised an average of 4 Animal Unit. If as being planned - such as scheme is adopted by 1,400 farmer, 230 worker will be employed in the first years. Employement need is increasing with time and

  11. Optimization of thermostable organic solvent-tolerant lipase production by thermotolerant Rhizopus sp. using solid-state fermentation of palm kernel cake.

    Science.gov (United States)

    Riyadi, Fatimah Azizah; Alam, Md Zahangir; Salleh, Md Noor; Salleh, Hamzah Mohd

    2017-10-01

    This study enhanced the production of thermostable organic solvent-tolerant (TS-OST) lipase by locally isolated thermotolerant Rhizopus sp. strain using solid-state fermentation (SSF) of palm kernel cake (PKC). The optimum conditions were achieved using a series of statistical approaches. The cultivation parameters, which include fermentation time, moisture content, temperature, pH, inoculum size, various carbon and nitrogen sources, as well as other supplements, were initially screened by the definitive screening design, and one-factor-at-a-time using PKC as the basal medium. Three significant factors (olive oil concentration, pH, and inoculum size) were further optimized using face-centred central composite design. The results indicated a successful and significant improvement of lipase activity by almost two-fold compared to the initial screening production. The findings showed that the optimal conditions were 2% (v/w) inoculum size, 2% (v/w) olive oil, 0.6% (w/w) peptone, 2% (v/w) ethanol, 70% moisture content at initial pH 10.0 and 45 °C within 72 h of fermentation. Process optimization resulted in maximum lipase activity of 58.63 U/gram dry solids (gds). The analysis of variance showed that the statistical model was significant (p value <0.0001) and reliable with a high value of R2 (0.98) and adjusted R2 (0.96). This indicates a better correlation between the actual and predicted responses of lipase production. By considering this study, the low-cost PKC through SSF appears to be promising in the utilization of agro-industrial waste for TS-OST lipase production. This is because satisfactory enzyme activity could be attained that promises industrial applications.

  12. Optimization of Indium Recovery and Separation from LCD Waste by Solvent Extraction with Bis(2-ethylhexyl Phosphate (D2EHPA

    Directory of Open Access Journals (Sweden)

    Jiaxu Yang

    2014-01-01

    Full Text Available Indium tin oxide (ITO is currently the choice of electrode material in liquid crystal displays (LCDs. D2EHPA is known to be an extractant that can be used to selectively recover indium from 1 M sulfuric acid. In order to optimize the extraction and separation of indium from LCD waste, the effects of pH, temperature, time, and extractant concentration on the distribution ratios of In(III and the major impurities such as Al(III, Cu(II, Fe(III, and Zn(II were investigated. Metal concentrations in the aqueous feed were based on the concentrations found in the leach liquor of LCD panel glass at 0.1 g/mL S/L ratio. This study showed that extraction of indium could be increased at 293 K. Furthermore, by increasing D2EHPA concentration from 0.1 M to 0.25 M, extraction of indium could be increased from 70% to >95%.

  13. Optimal Information Representation and Criticality in an Adaptive Sensory Recurrent Neuronal Network.

    Directory of Open Access Journals (Sweden)

    Oren Shriki

    2016-02-01

    Full Text Available Recurrent connections play an important role in cortical function, yet their exact contribution to the network computation remains unknown. The principles guiding the long-term evolution of these connections are poorly understood as well. Therefore, gaining insight into their computational role and into the mechanism shaping their pattern would be of great importance. To that end, we studied the learning dynamics and emergent recurrent connectivity in a sensory network model based on a first-principle information theoretic approach. As a test case, we applied this framework to a model of a hypercolumn in the visual cortex and found that the evolved connections between orientation columns have a "Mexican hat" profile, consistent with empirical data and previous modeling work. Furthermore, we found that optimal information representation is achieved when the network operates near a critical point in its dynamics. Neuronal networks working near such a phase transition are most sensitive to their inputs and are thus optimal in terms of information representation. Nevertheless, a mild change in the pattern of interactions may cause such networks to undergo a transition into a different regime of behavior in which the network activity is dominated by its internal recurrent dynamics and does not reflect the objective input. We discuss several mechanisms by which the pattern of interactions can be driven into this supercritical regime and relate them to various neurological and neuropsychiatric phenomena.

  14. An Optimized WSN Design for Latency-Critical Smart Grid Applications

    Directory of Open Access Journals (Sweden)

    Mounib Khanafer

    2017-01-01

    Full Text Available The growing popularity of the Internet of Things (IoT systems such as the smart grid, Body Area Networks (BANs, and the Intelligent Transportation System (ITS is driving Wireless Sensor Network (WSN systems to the limit in terms of abilities and performance. WSNs were initially designed for low power, low data rate, and latency-tolerant applications. However, this paradigm is changing because of the nature of the new applications. Therefore, instead of only focusing on power-efficient WSN design, researchers and industries are now developing Quality of Service (QoS protocols for WSNs. In addition to that, latency- and reliability-critical protocol designs are also becoming significantly important in WSNs. In this paper, we present an overview of some important smart grid latency-critical applications and highlight WSNs implementation challenges for these smart grid applications. Furthermore, we develop and evaluate two novel optimization models that solve for the optimum values of the end-to-end latency and power consumption in a clustered WSN given lower bounds on reliability and other network parameters.

  15. The actor-critic learning is behind the matching law: matching versus optimal behaviors.

    Science.gov (United States)

    Sakai, Yutaka; Fukai, Tomoki

    2008-01-01

    The ability to make a correct choice of behavior from various options is crucial for animals' survival. The neural basis for the choice of behavior has been attracting growing attention in research on biological and artificial neural systems. Alternative choice tasks with variable ratio (VR) and variable interval (VI) schedules of reinforcement have often been employed in studying decision making by animals and humans. In the VR schedule task, alternative choices are reinforced with different probabilities, and subjects learn to select the behavioral response rewarded more frequently. In the VI schedule task, alternative choices are reinforced at different average intervals independent of the choice frequencies, and the choice behavior follows the so-called matching law. The two policies appear robustly in subjects' choice of behavior, but the underlying neural mechanisms remain unknown. Here, we show that these seemingly different policies can appear from a common computational algorithm known as actor-critic learning. We present experimentally testable variations of the VI schedule in which the matching behavior gives only a suboptimal solution to decision making and show that the actor-critic system exhibits the matching behavior in the steady state of the learning even when the matching behavior is suboptimal. However, it is found that the matching behavior can earn approximately the same reward as the optimal one in many practical situations.

  16. Implementation of quality by design principles in the development of microsponges as drug delivery carriers: Identification and optimization of critical factors using multivariate statistical analyses and design of experiments studies.

    Science.gov (United States)

    Simonoska Crcarevska, Maja; Dimitrovska, Aneta; Sibinovska, Nadica; Mladenovska, Kristina; Slavevska Raicki, Renata; Glavas Dodov, Marija

    2015-07-15

    Microsponges drug delivery system (MDDC) was prepared by double emulsion-solvent-diffusion technique using rotor-stator homogenization. Quality by design (QbD) concept was implemented for the development of MDDC with potential to be incorporated into semisolid dosage form (gel). Quality target product profile (QTPP) and critical quality attributes (CQA) were defined and identified, accordingly. Critical material attributes (CMA) and Critical process parameters (CPP) were identified using quality risk management (QRM) tool, failure mode, effects and criticality analysis (FMECA). CMA and CPP were identified based on results obtained from principal component analysis (PCA-X&Y) and partial least squares (PLS) statistical analysis along with literature data, product and process knowledge and understanding. FMECA identified amount of ethylcellulose, chitosan, acetone, dichloromethane, span 80, tween 80 and water ratio in primary/multiple emulsions as CMA and rotation speed and stirrer type used for organic solvent removal as CPP. The relationship between identified CPP and particle size as CQA was described in the design space using design of experiments - one-factor response surface method. Obtained results from statistically designed experiments enabled establishment of mathematical models and equations that were used for detailed characterization of influence of identified CPP upon MDDC particle size and particle size distribution and their subsequent optimization. Copyright © 2015 Elsevier B.V. All rights reserved.

  17. Optimal amount of calories for critically ill patients: depends on how you slice the cake!

    Science.gov (United States)

    Heyland, Daren K; Cahill, Naomi; Day, Andrew G

    2011-12-01

    The optimal amount of calories required by critically ill patients continues to be controversial. The objective of this study is to examine the relationship between the amount of calories administered and mortality. Prospective, multi-institutional audit. Three hundred fifty-two intensive care units from 33 countries. A total of 7,872 mechanically ventilated, critically ill patients who remained in the intensive care unit for at least 96 hrs. None. We evaluated the association between the amount of calories received and 60-day hospital mortality using various sample restriction and statistical adjustment techniques and demonstrate the influence of the analytic approach on the results. In the initial unadjusted analysis, we observe a significant association between increased caloric intake and increased mortality (odds ratio 1.28; 95% confidence interval 1.12-1.48 for patients receiving more than two-thirds of their caloric prescription vs. those receiving less than one-third of their prescription). Excluding days after permanent progression to oral intake attenuated the estimates of harm (unadjusted analysis: odds ratio 1.04; 95% confidence interval 0.90-1.20). Restricting the analysis to patients with at least 4 days in the intensive care unit before progression to oral intake and excluding days of observation after progression to oral intake resulted in a significant benefit to increased caloric intake (unadjusted odds ratio 0.73; 95% confidence interval 0.63-0.85). When further adjusting for both evaluable days and other important covariates, patients who received more than two-thirds of their caloric prescription are much less likely to die than those receiving less than one-third of their prescription (odds ratio 0.67; 95% confidence interval 0.56-0.79; p calories associated with decreasing mortality (p calories and mortality is significantly influenced by the statistical methodology used. The most appropriate available analyses suggest that attempting to meet

  18. Optimization of the production of biodiesel by a commercial immobilized lipase in a solvent-free system using a response surface methodology

    Directory of Open Access Journals (Sweden)

    ZORICA KNEZEVIC

    2008-02-01

    Full Text Available Response surface methodology was used for the evaluation of the effects of various factors on the synthesis of biodiesel catalyzed with immobilized lipase from Rhizomucor miehei in a solvent-free system. The production of biodiesel was optimized and model response equations were obtained, enabling the prediction of biodiesel production from the values of the four main factors. It would seem that the reaction temperature and the amount of water predominantly determined the conversion process while the methanol/oil molar ratio had no significant influence on the reaction rate. The temperature and amount of water showed negative interactive effects on the observed reaction rate per amount of enzyme. However, there were no significant interactions among the other variables according to the test of statistical significance. The highest yield of 10.15 mol kg-1 enzyme was observed at 45 °C with a 6:1 methanol to oil molar ratio and with no added water in the system.

  19. Optimization of an accelerated solvent extraction dispersive liquid-liquid microextraction method for the separation and determination of essential oil from Ligusticum chuanxiong Hort by gas chromatography with mass spectrometry.

    Science.gov (United States)

    Yang, Guang; Sun, Qiushi; Hu, Zhiyan; Liu, Hua; Zhou, Tingting; Fan, Guorong

    2015-10-01

    In this study, an accelerated solvent extraction dispersive liquid-liquid microextraction coupled with gas chromatography and mass spectrometry was established and employed for the extraction, concentration and analysis of essential oil constituents from Ligusticum chuanxiong Hort. Response surface methodology was performed to optimize the key parameters in accelerated solvent extraction on the extraction efficiency, and key parameters in dispersive liquid-liquid microextraction were discussed as well. Two representative constituents in Ligusticum chuanxiong Hort, (Z)-ligustilide and n-butylphthalide, were quantitatively analyzed. It was shown that the qualitative result of the accelerated solvent extraction dispersive liquid-liquid microextraction approach was in good agreement with that of hydro-distillation, whereas the proposed approach took far less extraction time (30 min), consumed less plant material (usually extraction and analysis of essential oil. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. What is the optimal blood glucose target in critically ill patients? A nested cohort study

    Directory of Open Access Journals (Sweden)

    Ashraf Al-Tarifi

    2011-01-01

    Full Text Available Aims: There is an uncertainty about what constitutes an optimal level of blood glucose (BG in critically ill patients. The objective of this study is to identify the optimal BG target for glycemic control in critically ill patients that is associated with survival benefit with the least hypoglycemia risk. Setting and Design: This is a nested cohort study within a randomized control trial conducted in a tertiary care center in King Abdulaziz Medical City, Riyadh, Kingdom of Saudi Arabia. Methods: The study was carried out in a single center to assess the effect of intensive insulin therapy [IIT; target BG 4.4-6.1 mmol/L (80-110 mg/dL] versus conventional insulin therapy [CIT; target BG 10-11.1 mmol/L (180-200 mg/dL] in a medical/surgical ICU. All patients were divided into six groups based on the mean daily BG levels. A logistic regression model was used to determine the association of BG and ICU mortality. We compared different outcomes below and above different BG thresholds of 0.1 mmol/L (2 mg/dL increments using multivariate analyses. Statistical Analysis: Data are presented as mean ± SD or median with interquartile ranges, unless otherwise indicated. Differences between the six groups were assessed using the c΂ test. A P-value equal or less than 0.05 was considered to indicate statistical significance. The results were expressed as adjusted odds ratio (aOR and 95% confidence intervals (CI. Statistical analyses were carried out using the Statistical Analysis Software (SAS, release 8, SAS Institute Inc., Cary, NC, USA. Results: Among six groups, the ICU mortality was least in patients with BG <8.7 mmol/L (<157 mg/dL compared with patients with BG ≥8.7 mmol/L (≥157 mg/dL [11.5% vs. 21.5%, P = 0.002]. When analyzed using 0.1 mmol increments in average BG, we found that mortality remained unchanged by increasing thresholds of BG up to 8.0 mmol/L (144 mg/dL and started to rise with thresholds of BG of 8.1 mmol/L (146 mg/dL and above. The

  1. The Efficacy of a Restart Break for Recycling with Optimal Performance Depends Critically on Circadian Timing

    Science.gov (United States)

    Van Dongen, Hans P.A.; Belenky, Gregory; Vila, Bryan J.

    2011-01-01

    deficits. Conclusions: The 34-hour restart break was adequate for maintaining performance in the case of optimal circadian placement of sleep and duty periods (control condition) but was inadequate (and perhaps even detrimental) for maintaining performance in a simulated nighttime duty schedule (experimental condition). Current US transportation hours-of-service regulations mandate time off duty but do not consider the circadian aspects of shift scheduling. Reinforcing a recent trend of applying sleep science to inform policymaking for duty and rest times, our findings indicate that restart provisions in hours-of-service regulations could be improved by taking the circadian timing of the duty schedules into account. Citation: Van Dongen HPA; Belenky G; Vila BJ. The efficacy of a restart break for recycling with optimal performance depends critically on circadian timing. SLEEP 2011;34(7):917-929. PMID:21731142

  2. A Critical Survey of Optimization Models for Tactical and Strategic Aspects of Air Traffic Flow Management

    Science.gov (United States)

    Bertsimas, Dimitris; Odoni, Amedeo

    1997-01-01

    This document presents a critical review of the principal existing optimization models that have been applied to Air Traffic Flow Management (TFM). Emphasis will be placed on two problems, the Generalized Tactical Flow Management Problem (GTFMP) and the Ground Holding Problem (GHP), as well as on some of their variations. To perform this task, we have carried out an extensive literature review that has covered more than 40 references, most of them very recent. Based on the review of this emerging field our objectives were to: (i) identify the best available models; (ii) describe typical contexts for applications of the models; (iii) provide illustrative model formulations; and (iv) identify the methodologies that can be used to solve the models. We shall begin our presentation below by providing a brief context for the models that we are reviewing. In Section 3 we shall offer a taxonomy and identify four classes of models for review. In Sections 4, 5, and 6 we shall then review, respectively, models for the Single-Airport Ground Holding Problem, the Generalized Tactical FM P and the Multi-Airport Ground Holding Problem (for the definition of these problems see Section 3 below). In each section, we identify the best available models and discuss briefly their computational performance and applications, if any, to date. Section 7 summarizes our conclusions about the state of the art.

  3. Multivariate optimization of solvent bar microextraction combined with HPLC-UV for determination of trace amounts of vincristine in biological fluids.

    Science.gov (United States)

    Kiani, Mahsa; Qomi, Mahnaz; Hashemian, Farshad; Rajabi, Mehdi

    2017-10-29

    In the current work, an efficient method named solvent bar microextraction-high performance liquid chromatography-UV detection (HPLC-UV) was developed for preconcentration and determining the trace amount of vincristine (VCR) in biological samples such as plasma and urine. Briefly, VCR was extracted from an aqueous sample with pH 10.7 (donor phase) into 1-octanol as the supported liquid membrane (SLM) which is inserted into the pores of the hollow fiber and followed by back extraction into an aqueous receiving phase (pH=3.1). Studying the factors affecting the extraction performance in order to achieve a high extraction efficiency, requires the design of experiments (DOE) approach. In this regards, diverse factors' effects including the pH value of donor and acceptor phases, extraction time, extraction temperature, stirring rate and salt content of the donor phase were considered. The optimum experimental condition was as following: pH of the source phase, 10.7; pH of the receiving phase, 3.1; stirring rate, 1000rpm; extraction temperature, 51°C; extraction time, 60min and 11.3% w/v NaCl in the sample solution. Under the optimal; extraction condition, a favorable preconcentration factor equal to 98.5 was achieved. The linearity range was obtained in the domain of 0.05-5mgL-1. The limits of detection and quantification were 0.015 and 0.05mgL-1. Within-day and between-day RSDs of the proposed SBME method were 4.1% and 12.5%, respectively. Finally, the applicability of the implemented SBME method was evaluated by the extraction and quantification of VCR from biological samples such as urine and plasma and satisfactory results were obtained. Copyright © 2017. Published by Elsevier B.V.

  4. Optimized purification of a fusion protein by reversed-phase high performance liquid chromatography informed by the linear solvent strength model.

    Science.gov (United States)

    Falconer, Isaac B; Mant, Colin T; McKnight, C James; Vugmeyster, Liliya; Hodges, Robert

    2017-10-27

    Fusion protein systems are commonly used for expression of small proteins and peptides. An important criterion for a fusion protein system to be useful is the ability to separate the protein of interest from the tag. Additionally, because no protease cleaves fusion proteins with 100% efficiency, the ability to separate the desired peptide from any remaining uncleaved protein is also necessary. This is likely to be the more difficult task as at least a portion of the sequence of the fusion protein is identical to that of the protein of interest. When a high level of purity is required, gradient elution reversed-phase HPLC is frequently used as a final purification step. Shallow gradients are often advantageous for maximizing both the purity and yield of the final product; however, the relationship between relative retention times at shallow gradients and those at steeper gradients typically used for analytical HPLC are not always straightforward. In this work, we report reversed-phase HPLC results for the fusion protein system consisting of the N-terminal domain of ribosomal protein L9 (NTL9) and the 36-residue villin headpiece subdomain (HP36) linked by a recognition sequence for the protease factor Xa. This system represents an excellent example of the difficulties in purification that may arise from this unexpected elution behavior at shallow gradients. Additionally, we report on the sensitivity of this elution behavior to the concentration of the additive trifluoroacetic acid in the mobile phase and present optimized conditions for separating HP36 from the full fusion protein by reversed-phase HPLC using a shallow gradient. Finally, we suggest that these findings are relevant to the purification of other fusion protein systems, for which similar problems may arise, and support this suggestion using insights from the linear solvent strength model of gradient elution liquid chromatography. Copyright © 2017 Elsevier B.V. All rights reserved.

  5. Optimized Deep UV Curing Process for Metal-Free Dry-Etching of Critical Integrated Optical Devices

    NARCIS (Netherlands)

    Sengo, G.; Sengo, G.; van Wolferen, Hendricus A.G.M.; Driessen, A.

    In this paper we present results of Deep UV-curing of resist followed by thermal treatment at temperatures up to 280°C. The curing process was optimized for positive resist profiles of Fujifilm with thicknesses from 0.3 to 3.0 µm. The procedure was for the first time employed to etch critical

  6. Development and optimization of a naphthoic acid-based ionic liquid as a "non-organic solvent microextraction" for the determination of tetracycline antibiotics in milk and chicken eggs.

    Science.gov (United States)

    Gao, Jiajia; Wang, Hui; Qu, Jingang; Wang, Huili; Wang, Xuedong

    2017-01-15

    In traditional ionic liquids (ILs)-based microextraction, ILs are often used as extraction and dispersive solvents; however, their functional effects are not fully utilized. Herein, we developed a novel ionic liquid 1-butyl-3-methylimidazolium naphthoic acid salt ([C4MIM][NPA]) with strong acidity. It was used as a mixed dispersive solvent with conventional [C2MIM][BF4] in "functionalized ionic liquid-based non-organic solvent microextraction (FIL-NOSM)" for determination of tetracycline antibiotics (TCs) in milk and eggs. Utilization of [C4MIM][NPA] in FIL-NOSM method increased extraction recoveries (ERs) of TCs by more than 20% and eliminated the pH adjustment step because of its strong acidity. Under optimized conditions based on central composite design, the ERs of four TCs were 94.1-102.1%, and the limitsofdetection were 0.08-1.12μgkg(-1) in milk and egg samples. This proposed method provides high extraction efficiency, less pretreatment time and requires non-organic solvents for determination of trace TC concentrations in complex animal-based food matrices. Copyright © 2016 Elsevier Ltd. All rights reserved.

  7. Optimization of the Critical Diameter and Average Path Length of Social Networks

    Directory of Open Access Journals (Sweden)

    Haifeng Du

    2017-01-01

    Full Text Available Optimizing average path length (APL by adding shortcut edges has been widely discussed in connection with social networks, but the relationship between network diameter and APL is generally ignored in the dynamic optimization of APL. In this paper, we analyze this relationship and transform the problem of optimizing APL into the problem of decreasing diameter to 2. We propose a mathematic model based on a memetic algorithm. Experimental results show that our algorithm can efficiently solve this problem as well as optimize APL.

  8. Proceedings of the 2016 Clinical Nutrition Week Research Workshop-The Optimal Dose of Protein Provided to Critically Ill Patients.

    Science.gov (United States)

    Heyland, Daren K; Rooyakers, Olav; Mourtzakis, Marina; Stapleton, Renee D

    2017-02-01

    Recent literature has created considerable confusion about the optimal amount of protein/amino acids that should be provided to the critically ill patient. In fact, the evidentiary basis that directly tries to answer this question is relatively small. As a clinical nutrition research community, there is an urgent need to develop the optimal methods to assess the impact of exogenous protein/amino acid administration in the intensive care unit setting. That assessment can be conducted at various levels: (1) impact on stress response pathways, (2) impact on muscle synthesis and protein balance, (3) impact on muscle mass and function, and (4) impact on the patient's recovery. The objective of this research workshop was to review current literature relating to protein/amino acid administration for the critically ill patient and clinical outcomes and to discuss the key measurement and methodological features of future studies that should be done to inform the optimal protein/amino acid dose provided to critically ill patients.

  9. Critical Comparison of Multi-objective Optimization Methods: Genetic Algorithms versus Swarm Intelligence

    Directory of Open Access Journals (Sweden)

    V. Sedenka

    2010-09-01

    Full Text Available The paper deals with efficiency comparison of two global evolutionary optimization methods implemented in MATLAB. Attention is turned to an elitist Non-dominated Sorting Genetic Algorithm (NSGA-II and a novel multi-objective Particle Swarm Optimization (PSO. The performance of optimizers is compared on three different test functions and on a cavity resonator synthesis. The microwave resonator is modeled using the Finite Element Method (FEM. The hit rate and the quality of the Pareto front distribution are classified.

  10. Stabilization of Li Metal Anode in DMSO-Based Electrolytes via Optimization of Salt-Solvent Coordination for Li-O 2 Batteries

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Bin [Energy and Environment Directorate, Pacific Northwest National Laboratory, Richland WA 99354 USA; Xu, Wu [Energy and Environment Directorate, Pacific Northwest National Laboratory, Richland WA 99354 USA; Yan, Pengfei [Environmental and Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland WA 99354 USA; Kim, Sun Tai [Energy and Environment Directorate, Pacific Northwest National Laboratory, Richland WA 99354 USA; Department of Energy Engineering, School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology, Ulsan 689-798 South Korea; Engelhard, Mark H. [Environmental and Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland WA 99354 USA; Sun, Xiuliang [Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland WA 99354 USA; Mei, Donghai [Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland WA 99354 USA; Cho, Jaephil [Department of Energy Engineering, School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology, Ulsan 689-798 South Korea; Wang, Chong-Min [Environmental and Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland WA 99354 USA; Zhang, Ji-Guang [Energy and Environment Directorate, Pacific Northwest National Laboratory, Richland WA 99354 USA

    2017-03-08

    The conventional DMSO-based electrolyte (1 M lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) in DMSO) is unstable against the Li metal anode and therefore cannot be used directly in practical Li-O2 batteries. Here, we demonstrate that a highly concentrated electrolyte based on LiTFSI in DMSO (with a molar ratio of 1:3) can greatly improve the stability of the Li metal anode against DMSO and significantly improve the cycling stability of Li-O2 batteries. This highly concentrated electrolyte contains no free DMSO solvent molecules, but only complexes of (TFSI–)a-Li+-(DMSO)b (where a + b = 4), and thus enhances their stability with Li metal anodes. In addition, such salt-solvent complexes have higher Gibbs activation energy barriers than the free DMSO solvent molecules, indicating improved stability of the electrolyte against the attack of superoxide radical anions. Therefore, the stability of this highly concentrated electrolyte at both Li metal anodes and carbon-based air electrodes has been greatly enhanced, resulting in improved cyclic stability of Li-O2 batteries. The fundamental stability of the electrolyte with free-solvent against the chemical and electrochemical reactions can also be used to enhance the stability of other electrochemical systems.

  11. Optimal Concentration of Organic Solvents to be Used in the Broth Microdilution Method to Determine the Antimicrobial Activity of Natural Products Against Paenibacillus Larvae

    Directory of Open Access Journals (Sweden)

    Cugnata Noelia Melina

    2017-06-01

    Full Text Available American Foulbrood (AFB is a bacterial disease, caused by Paenibacillus larvae, that affects honeybees (Apis mellifera. Alternative strategies to control AFB are based on the treatment of the beehives with antimicrobial natural substances such as extracts, essential oils and/or pure compounds from plants, honey by-products, bacteria and moulds. The broth microdilution method is currently one of the most widely used methods to determine the minimum inhibitory concentration (MIC of a substance. In this regard, the fact that most natural products, due to their lipophilic nature, must be dissolved in organic solvents or their aqueous mixtures is an issue of major concern because the organic solvent becomes part of the dilution in the incubation medium, and therefore, can interfere with bacterial viability depending on its nature and concentration. A systematic study was carried out to determine by the broth microdilution method the MIC and the maximum non inhibitory concentration (MNIC against P. larvae of the most common organic solvents used to extract or dissolve natural products, i.e. ethanol, methanol, acetonitrile, n-butanol, dimethylsulfoxide, and acidified hydromethanolic solutions. From the MIC and MNIC for each organic solvent, recommended maximum concentrations in contact with P. larvae were established: DMSO 5% (v/v, acetonitrile 7.5% (v/v, ethanol 7.5% (v/v, methanol 12% (v/v, n-butanol 1% (v/v, and methanol-water-acetic acid (1.25:98.71:0.04, v/v/v.

  12. Fuzzy Optimization of Construction Engineering Project Schedule Based on Critical Chain Management

    OpenAIRE

    Liu, Jianbing; Ren, Hong; Junshu DU

    2013-01-01

    Critical chain management was the very important theory innovation in the development of construction project schedule management field in recent years. Compared with the traditional methods of construction project schedule management, the methods of critical chain management considered resource constraints into construction project schedule management, the construction project cycle was shortened and the efficiency was enhanced by using the dynamic thinking and circulation pattern to manage ...

  13. Optimization of large-volume on-column injection conditions in gas chromatography by monitoring the actual carrier gas flow.

    NARCIS (Netherlands)

    Hankemeier, Th.; Kok, S.J.; Vreuls, J.J.; Brinkman, U.A.T.

    1999-01-01

    The change of the evaporation rate of the solvent during injection and evaporation is the most critical aspect during optimization of large-volume on-column injection conditions in gas chromatography. The change is caused by the pressure drop along the retention gap when using an early solvent

  14. Optimal nutrition therapy in paediatric critical care in the Asia-Pacific and Middle East: a consensus.

    Science.gov (United States)

    Lee, Jan Hau; Rogers, Elizabeth; Chor, Yek Kee; Samransamruajkit, Rujipat; Koh, Pei Lin; Miqdady, Mohamad; Al-Mehaidib, Ali Ibrahim; Pudjiadi, Antonius; Singhi, Sunit; Mehta, Nilesh M

    2016-12-01

    Current practices and available resources for nutrition therapy in paediatric intensive care units (PICUs) in the Asia Pacific-Middle East region are expected to differ from western countries. Existing guidelines for nutrition management in critically ill children may not be directly applicable in this region. This paper outlines consensus statements developed by the Asia Pacific-Middle East Consensus Working Group on Nutrition Therapy in the Paediatric Critical Care Environment. Challenges and recommendations unique to the region are described. Following a systematic literature search from 2004-2014, consensus statements were developed for key areas of nutrient delivery in the PICU. This review focused on evidence applicable to the Asia Pacific-Middle East region. Quality of evidence and strength of recommendations were rated according to the Grading of Recommendation Assessment, Development and Evaluation approach. Enteral nutrition (EN) is the preferred mode of nutritional support. Feeding algorithms that optimize EN should be encouraged and must include: assessment and monitoring of nutritional status, selection of feeding route, time to initiate and advance EN, management strategies for EN intolerance and indications for using parenteral nutrition (PN). Despite heterogeneity in nutritional status of patients, availability of resources and diversity of cultures, PICUs in the region should consider involvement of dieticians and/or nutritional support teams. Robust evidence for several aspects of optimal nutrition therapy in PICUs is lacking. Nutritional assessment must be implemented to document prevalence and impact of malnutrition. Nutritional support must be given greater priority in PICUs, with particular emphasis in optimizing EN delivery.

  15. Optimization of extraction yield of carthamine and safflower yellow pigments from safflower (Carthamus tinctorious L. under different treatments and solvent systems

    Directory of Open Access Journals (Sweden)

    E. Ghorbani

    2015-12-01

    Full Text Available Background and objectives: Safflower (Carthamus tinctorious L. florets contain valuable red and yellow pigments and are used in food, textile dying, and pharmaceutical industries. Red carthamine pigment is formed from a yellow precursor, precarthamine, through an oxidation reaction at the end of flowers' maturation stage. The present study was conducted to find out the most effective procedure for extraction and purification of yellow and red pigments from safflower florets. Methods: Two different experiments were designed to assess the suitability of oxidant reagents (KMnO4 and H2O2 on the reddening of florets and different alkaline and organic solutions were used as the solvents (KNO3, Na2CO3, ethanol/hexane, methanol, and NaOH in order to extract and purify the pigments. All obtained pigments were characterized chromatographically and spectrophotometrically for calculating the yield and evaluating purity of the extracted materials. Results: The results showed that KMnO4 and H2O2 treatments were significantly effective for increasing carthamine yield from safflower; but KMnO4 decreased the amount of yellow pigment extraction during the washing process of treated petals before extraction. Ethanol/hexane demonstrated to be effective in the extraction of yellow pigments, but it was not a good solvent for carthamine extraction. Except for the degassed bicarbonate which showed a high pigment yield, the other three solvents especially KNO3 did not appear to be of practical use for red pigment preparation. Conclusion: The present results showed that pretreatment of petals with hydrogen peroxide and then extracting by degassed solvents resulted in higher yield of red carthamine pigment, and also using reconditioned cellulose or cotton, instead of fresh cellulose, would reduce the cost.

  16. Nitrogen Fixation by a Molybdenum Catalyst Mimicking the Function of the Nitrogenase Enzyme:  A Critical Evaluation of DFT and Solvent Effects.

    Science.gov (United States)

    Magistrato, Alessandra; Robertazzi, Arturo; Carloni, Paolo

    2007-09-01

    Compounds mimicking the enzyme nitrogenase represent promising alternative routes to the current Haber-Bosch industrial synthesis of ammonia from molecular hydrogen and nitrogen. In this work, we investigated the full catalytic cycle of one of such compounds, Mo(HIPTN3N) (with HIPT = hexaisopropylterphenyl), by means of DFT calculations. Our results suggest these large ligands to exert mainly a steric influence on the structural properties of the catalyst. In addition, we provided a structural and electronic characterization of the putative reaction intermediates along with a picture of the electronic mechanism of molecular nitrogen N-N bond breaking. A large discrepancy was observed between calculated and experimental reaction free energies, suggesting that in the present case the predictability of DFT reaction energies is limited. Investigation of explicit solvation of specific catalytic intermediates as well as of the protonation and reducing agents reveal the crucial role played by the solvent molecules (benzene and heptane) particularly for protonation steps. Furthermore, the analysis of several DFT functionals indicates that these have to be carefully chosen in order to reproduce the energetic profile of reduction steps. This study shows how DFT calculations may be a powerful tool to describe structural and electronic properties of the intermediates of the catalytic cycle, yet, due to the complexity of the system, reaction energies cannot be easily reproduced without a careful choice of the solvation model and the exchange-correlation functional.

  17. The Optimal Dose of Midazolam for Promoting Sleep in Critically Ill Patients: A Pilot Study

    Directory of Open Access Journals (Sweden)

    Se Joong Kim

    2014-08-01

    CONCLUSIONS: The appropriate quantity of sleep in critically ill patients was achieved with a continuous infusion of 0.02-0.03 mg/kg/h midazolam. However, the quality of sleep was poor. Further study is required for the promotion of quality sleep in such patients.

  18. Right dose, right now: using big data to optimize antibiotic dosing in the critically ill.

    Science.gov (United States)

    Elbers, Paul W G; Girbes, Armand; Malbrain, Manu L N G; Bosman, Rob

    2015-01-01

    Antibiotics save lives and are essential for the practice of intensive care medicine. Adequate antibiotic treatment is closely related to outcome. However this is challenging in the critically ill, as their pharmacokinetic profile is markedly altered. Therefore, it is surprising that critical care physicians continue to rely on standard dosing regimens for every patient, regardless of the actual clinical situation. This review outlines the pharmacokinetic and pharmacodynamic principles that underlie the need for individualized and personalized drug dosing. At present, therapeutic drug monitoring may be of help, but has major disadvantages, remains unavailable for most antibiotics and has produced mixed results. We therefore propose the AutoKinetics concept, taking decision support for antibiotic dosing back to the bedside. By direct interaction with electronic patient records, this opens the way for the use of big data for providing the right dose at the right time in each patient.

  19. Optimal system size for complex dynamics in random neural networks near criticality

    Energy Technology Data Exchange (ETDEWEB)

    Wainrib, Gilles, E-mail: wainrib@math.univ-paris13.fr [Laboratoire Analyse Géométrie et Applications, Université Paris XIII, Villetaneuse (France); García del Molino, Luis Carlos, E-mail: garciadelmolino@ijm.univ-paris-diderot.fr [Institute Jacques Monod, Université Paris VII, Paris (France)

    2013-12-15

    In this article, we consider a model of dynamical agents coupled through a random connectivity matrix, as introduced by Sompolinsky et al. [Phys. Rev. Lett. 61(3), 259–262 (1988)] in the context of random neural networks. When system size is infinite, it is known that increasing the disorder parameter induces a phase transition leading to chaotic dynamics. We observe and investigate here a novel phenomenon in the sub-critical regime for finite size systems: the probability of observing complex dynamics is maximal for an intermediate system size when the disorder is close enough to criticality. We give a more general explanation of this type of system size resonance in the framework of extreme values theory for eigenvalues of random matrices.

  20. A SYSTEMATIC CRITICAL OPTIMIZING INTEGRATION KINEMATIC ALGORITHM OF DIGITAL RTOS SYSTEM FOR KUKA KR16 ROBOT

    OpenAIRE

    Dr Alok Mishra*1 & Dr Kamlesh Singh2

    2017-01-01

    The problem of Critical system analysis and finding mathematical tools to represent industrial robot manipulators is to achieve desired position for rigid body motions in space. 6R is considered to be a well-researched with rooting and well-understood mathematical problem. Industrial Robotics, machine vision, computer graphics, and other Dynamics Engineering disciplines require co concise and efficient improve means of representing and applying fiberized coordinate motion kinematics transform...

  1. Controlling solution-phase polymer aggregation with molecular weight and solvent additives to optimize polymer-fullerene bulk heterojunction solar cells

    KAUST Repository

    Bartelt, Jonathan A.

    2014-03-20

    The bulk heterojunction (BHJ) solar cell performance of many polymers depends on the polymer molecular weight (M n) and the solvent additive(s) used for solution processing. However, the mechanism that causes these dependencies is not well understood. This work determines how M n and solvent additives affect the performance of BHJ solar cells made with the polymer poly(di(2-ethylhexyloxy)benzo[1,2-b:4,5-b\\']dithiophene-co- octylthieno[3,4-c]pyrrole-4,6-dione) (PBDTTPD). Low M n PBDTTPD devices have exceedingly large fullerene-rich domains, which cause extensive charge-carrier recombination. Increasing the M n of PBDTTPD decreases the size of these domains and significantly improves device performance. PBDTTPD aggregation in solution affects the size of the fullerene-rich domains and this effect is linked to the dependency of PBDTTPD solubility on M n. Due to its poor solubility high M n PBDTTPD quickly forms a fibrillar polymer network during spin-casting and this network acts as a template that prevents large-scale phase separation. Furthermore, processing low M n PBDTTPD devices with a solvent additive improves device performance by inducing polymer aggregation in solution and preventing large fullerene-rich domains from forming. These findings highlight that polymer aggregation in solution plays a significant role in determining the morphology and performance of BHJ solar cells. The performance of poly(di(2-ethylhexyloxy) benzo[1,2-b:4,5-b\\']dithiophene-co-octylthieno[3,4-c]pyrrole-4,6-dione) (PBDTTPD) bulk heterojunction solar cells strongly depends on the polymer molecular weight, and processing these bulk heterojunctions with a solvent additive preferentially improves the performance of low molecular weight devices. It is demonstrated that polymer aggregation in solution significantly impacts the thin-film bulk heterojunction morphology and is vital for high device performance. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Optimal distributed generation placement in distribution system to improve reliability and critical loads pick up after natural disasters

    Directory of Open Access Journals (Sweden)

    Galiveeti Hemakumar Reddy

    2017-06-01

    Full Text Available The increase in frequency of natural disasters has necessitated the need of resilient distribution systems. Natural disasters lead to severe damage of power system infrastructure and the main grid may not be available to serve the loads. The integration of distributed generation (DG into distribution system partially restores the loads after natural disasters and improves the reliability during normal operating conditions. After a natural disaster, objective of the system operators is to restore the critical loads as a priority. This enables the need of considering critical load pick up as an objective function while placing the DGs. A location based constraint is, thus, required to make sure the DGs are available to pick up the loads after natural disasters. Fuzzy multi criteria decision making (FMCDM approach is used in this work to rank the load points and locations/feeder sections. This paper uses particle swarm optimization (PSO to evaluate the optimal size and location of DGs using the proposed objective function. The obtained results are compared with the results of reliability as an objective function.

  3. Degreaser Reduces Solvent Loss

    Science.gov (United States)

    Du Fresne, E. R.

    1985-01-01

    Escape of solvent minimized by second cooling coil. Degreaser suppresses solvent-vapor loss through parts-basket dragout and air drafts. Within C02 blanket, convection repeatedly exposes C02/solvent mixture to cold spot created by C02 coil. Solvent vapor condenses, then runs down via through to cold tank. This small expenditure of C02 minimizes health and environmental hazards.

  4. Structural insights of ZIP4 extracellular domain critical for optimal zinc transport

    Science.gov (United States)

    Zhang, Tuo; Sui, Dexin; Hu, Jian

    2016-06-01

    The ZIP zinc transporter family is responsible for zinc uptake from the extracellular milieu or intracellular vesicles. The LIV-1 subfamily, containing nine out of the 14 human ZIP proteins, is featured with a large extracellular domain (ECD). The critical role of the ECD is manifested by disease-causing mutations on ZIP4, a representative LIV-1 protein. Here we report the first crystal structure of a mammalian ZIP4-ECD, which reveals two structurally independent subdomains and an unprecedented dimer centred at the signature PAL motif. Structure-guided mutagenesis, cell-based zinc uptake assays and mapping of the disease-causing mutations indicate that the two subdomains play pivotal but distinct roles and that the bridging region connecting them is particularly important for ZIP4 function. These findings lead to working hypotheses on how ZIP4-ECD exerts critical functions in zinc transport. The conserved dimeric architecture in ZIP4-ECD is also demonstrated to be a common structural feature among the LIV-1 proteins.

  5. The efficacy of a restart break for recycling with optimal performance depends critically on circadian timing.

    Science.gov (United States)

    Van Dongen, Hans P A; Belenky, Gregory; Vila, Bryan J

    2011-07-01

    Under simulated shift-work conditions, we investigated the efficacy of a restart break for maintaining neurobehavioral functioning across consecutive duty cycles, as a function of the circadian timing of the duty periods. As part of a 14-day experiment, subjects underwent two cycles of five simulated daytime or nighttime duty days, separated by a 34-hour restart break. Cognitive functioning and high-fidelity driving simulator performance were tested 4 times per day during the two duty cycles. Lapses on a psychomotor vigilance test (PVT) served as the primary outcome variable. Selected sleep periods were recorded polysomnographically. The experiment was conducted under standardized, controlled laboratory conditions with continuous monitoring. Twenty-seven healthy adults (13 men, 14 women; aged 22-39 years) participated in the study. Subjects were randomly assigned to a nighttime duty (experimental) condition or a daytime duty (control) condition. The efficacy of the 34-hour restart break for maintaining neurobehavioral functioning from the pre-restart duty cycle to the post-restart duty cycle was compared between these two conditions. Relative to the daytime duty condition, the nighttime duty condition was associated with reduced amounts of sleep, whereas sleep latencies were shortened and slow-wave sleep appeared to be conserved. Neurobehavioral performance measures ranging from lapses of attention on the PVT to calculated fuel consumption on the driving simulators remained optimal across time of day in the daytime duty schedule, but degraded across time of night in the nighttime duty schedule. The 34-hour restart break was efficacious for maintaining PVT performance and other objective neurobehavioral functioning profiles from one duty cycle to the next in the daytime duty condition, but not in the nighttime duty condition. Subjective sleepiness did not reliably track objective neurobehavioral deficits. The 34-hour restart break was adequate for maintaining

  6. [The optimal blood glucose target in critically ill patient: comparison of two intensive insulin therapy protocols].

    Science.gov (United States)

    Raurell Torredà, Marta; del Llano Serrano, César; Almirall Solsona, Dolors; Catalan Ibars, Rosa María; Nicolás Arfelis, José María

    2014-03-04

    Recent studies in critically ill patients receiving insulin intravenous therapy (IIT) have shown an increased incidence of severe hypoglycemia, while intermittent subcutaneous insulin «sliding scales» (conventional insulin therapy [CIT]) is associated with hyperglycemia. The objective of this study is to assess whether glycemic control range IIT can affect glucose levels and their variability and to compare it with CIT. Prospective comparative cohort study in intensive care unit, with 2 study periods: Period 1, IIT with glycemic target range 110-140 mg/dL, and Period 2, IIT of 140-180 mg/dL. In both periods CIT glycemic target was 110-180 mg/dL. We assessed severe hypoglycemia ( 216 mg/L) and the variability of blood glucose. We studied 221 patients with 12.825 blood glucose determinations. Twenty-six and 17% of patients required IIT for glycemic control in Period 1 and 2, respectively. Hypoglycemia was associated with a discontinuous nutritional intake, glycemic target 110-140 mg/dL and low body mass index (BMI) (P = .002). Hyperglycemia was exclusively associated with a history of diabetes mellitus (OR 2.6 [95% CI 1.6 to 4.5]). Glycemic variability was associated with a discontinuous nutritional intake, low BMI, CIT insulinization, diabetes mellitus, elderly and high APACHE II (P < .001). The use of IIT is useful to reduce the variability of blood glucose. Although the 140-180 mg/dL range would be more secure as to presenting greater variability and hyperglycemia, the 110-140 mg/dL range is most suitable. Copyright © 2012 Elsevier España, S.L. All rights reserved.

  7. Optimal task mapping in safety-critical real-time parallel systems; Placement optimal de taches pour les systemes paralleles temps-reel critiques

    Energy Technology Data Exchange (ETDEWEB)

    Aussagues, Ch

    1998-12-11

    This PhD thesis is dealing with the correct design of safety-critical real-time parallel systems. Such systems constitutes a fundamental part of high-performance systems for command and control that can be found in the nuclear domain or more generally in parallel embedded systems. The verification of their temporal correctness is the core of this thesis. our contribution is mainly in the following three points: the analysis and extension of a programming model for such real-time parallel systems; the proposal of an original method based on a new operator of synchronized product of state machines task-graphs; the validation of the approach by its implementation and evaluation. The work addresses particularly the main problem of optimal task mapping on a parallel architecture, such that the temporal constraints are globally guaranteed, i.e. the timeliness property is valid. The results incorporate also optimally criteria for the sizing and correct dimensioning of a parallel system, for instance in the number of processing elements. These criteria are connected with operational constraints of the application domain. Our approach is based on the off-line analysis of the feasibility of the deadline-driven dynamic scheduling that is used to schedule tasks inside one processor. This leads us to define the synchronized-product, a system of linear, constraints is automatically generated and then allows to calculate a maximum load of a group of tasks and then to verify their timeliness constraints. The communications, their timeliness verification and incorporation to the mapping problem is the second main contribution of this thesis. FInally, the global solving technique dealing with both task and communication aspects has been implemented and evaluated in the framework of the OASIS project in the LETI research center at the CEA/Saclay. (author) 96 refs.

  8. Optimization of the Return-to-Sport Paradigm After Anterior Cruciate Ligament Reconstruction: A Critical Step Back to Move Forward.

    Science.gov (United States)

    Dingenen, Bart; Gokeler, Alli

    2017-08-01

    Athletes who have sustained an anterior cruciate ligament (ACL) injury often opt for an ACL reconstruction (ACLR) with the goal and expectation to resume sports. Unfortunately, the proportion of athletes successfully returning to sport is relatively low, while the rate of second ACL injury has been reported to exceed 20% after clearance to return to sport, especially within younger athletic populations. Despite the development of return-to-sport guidelines over recent years, there are still more questions than answers on the most optimal return-to-sport criteria after ACLR. The primary purpose of this review was to provide a critical appraisal of the current return-to-sport criteria and decision-making processes after ACLR. Traditional return-to-sport criteria mainly focus on time after injury and impairments of the injured knee joint. The return-to-sport decision making is only made at the hypothetical 'end' of the rehabilitation. We propose an optimized criterion-based multifactorial return-to-sport approach based on shared decision making within a broad biopsychosocial framework. A wide spectrum of sensorimotor and biomechanical outcomes should be assessed comprehensively, while the interactions of an individual athlete with the tasks being performed and the environment in which the tasks are executed are taken into account. A layered approach within a smooth continuum with repeated athletic evaluations throughout rehabilitation followed by a gradual periodized reintegration into sport with adequate follow-up may help to guide an individual athlete toward a successful return to sport.

  9. Optimization

    CERN Document Server

    Pearce, Charles

    2009-01-01

    Focuses on mathematical structure, and on real-world applications. This book includes developments in several optimization-related topics such as decision theory, linear programming, turnpike theory, duality theory, convex analysis, and queuing theory.

  10. Optimization, purification and characterization of novel thermostable, haloalkaline, solvent stable protease from Bacillus halodurans CAS6 using marine shellfish wastes: a potential additive for detergent and antioxidant synthesis.

    Science.gov (United States)

    Annamalai, Neelamegam; Rajeswari, Mayavan Veeramuthu; Thavasi, Rengathavasi; Vijayalakshmi, Shanmugam; Balasubramanian, Thangavel

    2013-07-01

    A protease producing marine bacterium, Bacillus halodurans CAS6 isolated from marine sediments, was found to produce higher enzyme by utilizing shrimp shell powder. Optimum culture conditions for protease production were 50 °C, pH 9.0, 30 % NaCl and 1 % shrimp shell powder (SSP) and the protease purified with a specific activity of 509.84 U/mg. The enzyme retained 100 % of its original activity even at 70 °C, pH 10.0 and 30 % NaCl for 1 h. The purified protease exhibited higher stability when treated with ionic, non-ionic (72-94 %) and commercial detergents (76-88 %), and organic solvents (88-126 %). Significant blood stain removal activity was found with the enzyme in washing experiments. The culture supernatant supplemented with 1 % SSP showed 93.67 ± 2.52 % scavenging activity and FT-IR analysis of the reaction mixture confirmed the presence of antioxidants such as cyclohexane and cyclic depsipeptide with aliphatic amino groups. These remarkable qualities found with this enzyme produced by Bacillus halodurans CAS6 could make this as an ideal candidate to develop the industrial process for bioconversion of marine wastes and antioxidant synthesis.

  11. Optimal extraction and fingerprint analysis of Cnidii fructus by accelerated solvent extraction and high performance liquid chromatographic analysis with photodiode array and mass spectrometry detections.

    Science.gov (United States)

    Gao, Fangyuan; Hu, Yongsheng; Ye, Xiaolan; Li, Ji; Chen, Zhao; Fan, Guorong

    2013-12-01

    A confirmatory and reliable procedure has been developed for extraction and determination of Cnidii fructus by accelerated solvent extraction (ASE) and high-performance liquid chromatography coupled with photodiode array, electrospray ionisation ion trap tandem mass spectrometry and time of flight mass spectrometry (HPLC-PDA-ESI-ITMS(n)/TOF-MS). The determination method enabled the characterisation of sixteen bioactive components in C. fructus and quantification of three major coumarins, namely osthole, imperatorin and isopimpinellin. Response surface methodology (RSM) was employed to optimise the extraction parameters yielding the optimum conditions of ASE (extraction temperature 122 °C, extraction time 5 min and two static cycles). And the total contents of three major coumarins extracted by ASE under the optimum conditions was significantly higher than those by reflux and ultrasonic extraction (P<0.05) with better reproducibility. At last, the proposed method coupled with pattern recognition was applied to analysis of C. fructus from eight different regions in China. Copyright © 2013 Elsevier Ltd. All rights reserved.

  12. How to design a good photoresist solvent package using solubility parameters and high-throughput research

    Science.gov (United States)

    Tate, Michael P.; Cutler, Charlotte; Sakillaris, Mike; Kaufman, Michael; Estelle, Thomas; Mohler, Carol; Tucker, Chris; Thackeray, Jim

    2014-03-01

    Understanding fundamental properties of photoresists and how interactions between photoresist components affect performance targets are crucial to the continued success of photoresists. More specifically, polymer solubility is critical to the overall performance capability of the photoresist formulation. While several theories describe polymer solvent solubility, the most common industrially applied method is Hansen's solubility parameters. Hansen's method, based on regular solution theory, describes a solute's ability to dissolve in a solvent or solvent blend using four physical properties determined experimentally through regression of solubility data in many known solvents. The four physical parameters are dispersion, polarity, hydrogen bonding, and radius of interaction. Using these parameters a relative cohesive energy difference (RED), which describes a polymer's likelihood to dissolve in a given solvent blend, may be calculated. Leveraging a high throughput workflow to prepare and analyze the thousands of samples necessary to calculate the Hansen's solubility parameters from many different methacrylate-based polymers, we compare the physical descriptors to reveal a large range of polarities and hydrogen bonding. Further, we find that Hansen's model correctly predicts the soluble/insoluble state of 3-component solvent blends where the dispersion, polar, hydrogen-bonding, and radius of interaction values were determined through regression of experimental values. These modeling capabilities have allowed for optimization of the photoresist solubility from initial blending through application providing valuable insights into the nature of photoresist.

  13. Conventional and accelerated-solvent extractions of green tea (camellia sinensis) for metabolomics-based chemometrics.

    Science.gov (United States)

    Kellogg, Joshua J; Wallace, Emily D; Graf, Tyler N; Oberlies, Nicholas H; Cech, Nadja B

    2017-10-25

    Metabolomics has emerged as an important analytical technique for multiple applications. The value of information obtained from metabolomics analysis depends on the degree to which the entire metabolome is present and the reliability of sample treatment to ensure reproducibility across the study. The purpose of this study was to compare methods of preparing complex botanical extract samples prior to metabolomics profiling. Two extraction methodologies, accelerated solvent extraction and a conventional solvent maceration, were compared using commercial green tea [Camellia sinensis (L.) Kuntze (Theaceae)] products as a test case. The accelerated solvent protocol was first evaluated to ascertain critical factors influencing extraction using a D-optimal experimental design study. The accelerated solvent and conventional extraction methods yielded similar metabolite profiles for the green tea samples studied. The accelerated solvent extraction yielded higher total amounts of extracted catechins, was more reproducible, and required less active bench time to prepare the samples. This study demonstrates the effectiveness of accelerated solvent as an efficient methodology for metabolomics studies. Copyright © 2017. Published by Elsevier B.V.

  14. NEPTUNIUM SOLVENT EXTRACTION PROCESS

    Science.gov (United States)

    Dawson, L.R.; Fields, P.R.

    1959-10-01

    The separation of neptunium from an aqueous solution by solvent extraction and the extraction of neptunium from the solvent solution are described. Neptunium is separated from an aqueous solution containing tetravalent or hexavalent neptunium nitrate, nitric acid, and a nitrate salting out agent, such as sodium nitrate, by contacting the solution with an organic solvent such as diethyl ether. Subsequently, the neptunium nitrate is extracted from the organic solvent extract phase with water.

  15. Towards Efficient Energy Management of Smart Buildings Exploiting Heuristic Optimization with Real Time and Critical Peak Pricing Schemes

    Directory of Open Access Journals (Sweden)

    Sheraz Aslam

    2017-12-01

    Full Text Available The smart grid plays a vital role in decreasing electricity cost through Demand Side Management (DSM. Smart homes, a part of the smart grid, contribute greatly to minimizing electricity consumption cost via scheduling home appliances. However, user waiting time increases due to the scheduling of home appliances. This scheduling problem is the motivation to find an optimal solution that could minimize the electricity cost and Peak to Average Ratio (PAR with minimum user waiting time. There are many studies on Home Energy Management (HEM for cost minimization and peak load reduction. However, none of the systems gave sufficient attention to tackle multiple parameters (i.e., electricity cost and peak load reduction at the same time as user waiting time was minimum for residential consumers with multiple homes. Hence, in this work, we propose an efficient HEM scheme using the well-known meta-heuristic Genetic Algorithm (GA, the recently developed Cuckoo Search Optimization Algorithm (CSOA and the Crow Search Algorithm (CSA, which can be used for electricity cost and peak load alleviation with minimum user waiting time. The integration of a smart Electricity Storage System (ESS is also taken into account for more efficient operation of the Home Energy Management System (HEMS. Furthermore, we took the real-time electricity consumption pattern for every residence, i.e., every home has its own living pattern. The proposed scheme is implemented in a smart building; comprised of thirty smart homes (apartments, Real-Time Pricing (RTP and Critical Peak Pricing (CPP signals are examined in terms of electricity cost estimation for both a single smart home and a smart building. In addition, feasible regions are presented for single and multiple smart homes, which show the relationship among the electricity cost, electricity consumption and user waiting time. Experimental results demonstrate the effectiveness of our proposed scheme for single and multiple smart

  16. Optimization of Process Parameters of Extraction of Amentoflavone, Quercetin and Ginkgetin from Taxus chinensis Using Supercritical CO2 Plus Co-Solvent

    Directory of Open Access Journals (Sweden)

    Xiao Ruan

    2014-10-01

    Full Text Available The effects of extraction time, temperature, pressure and different concentration of ethanol and their interactions on the yields of amentoflavone, quercetin and ginkgetin extracted from Taxus chinensis by supercritical CO2 were investigated by using a central composite design (CCD. An CCD experimental design with four factors and five levels was used to optimize the extraction parameters. Ultra performance liquid chromatography (UPLC was used to analyze the content of the tree components in the extracts. Experimental results show that the main effects of factors and their interactions are significant on the yields (p < 0.05. The optimal extraction conditions were established for the three compounds: yield of 4.47 mg/g for amentoflavone at 48 °C, 25 MPa, 2.02 h and 78.5% ethanol, 3.73 mg/g for quercetin at 46 °C, 24 MPa, 2.3 h, 82% ethanol and 3.47 mg/g for ginkgetin at 48 °C, 20 MPa, 2.38 h, 82% ethanol, respectively.

  17. Hydrogen recovery by novel solvent systems

    Energy Technology Data Exchange (ETDEWEB)

    Shinnar, R.; Ludmer, Z.; Ullmann, A.

    1991-08-01

    The objective of this work is to develop a novel method for purification of hydrogen from coal-derived synthesis gas. The study involved a search for suitable mixtures of solvents for their ability to separate hydrogen from the coal derived gas stream in significant concentration near their critical point of miscibility. The properties of solvent pairs identified were investigated in more detail to provide data necessary for economic evaluation and process development.

  18. Nonflammable, Nonaqueous, Low Atmospheric Impact, High Performance Cleaning Solvents

    Science.gov (United States)

    Dhooge, P. M.; Glass, S. M.; Nimitz, J. S.

    2001-01-01

    For many years, chlorofluorocarbon (CFC) and chlorocarbon solvents have played an important part in aerospace operations. These solvents found extensive use as cleaning and analysis (EPA) solvents in precision and critical cleaning. However, CFCs and chlorocarbon solvents have deleterious effects on the ozone layer, are relatively strong greenhouse gases, and some are suspect or known carcinogens. Because of their ozone-depletion potential (ODP), the Montreal Protocol and its amendments, as well as other environmental regulations, have resulted in the phaseout of CFC-113 and 1,1,1-trichloroethane (TCA). Although alternatives have been recommended, they do not perform as well as the original solvents. In addition, some analyses, such as the infrared analysis of extracted hydrocarbons, cannot be performed with the substitute solvents that contain C-H bonds. CFC-113 solvent has been used for many critical aerospace applications. CFC-113, also known as Freon (registered) TF, has been used extensively in NASA's cleaning facilities for precision and critical cleaning, in particular the final rinsing in Class 100 areas, with gas chromatography analysis of rinse residue. While some cleaning can be accomplished by other processes, there are certain critical applications where CFC-113 or a similar solvent is highly cost-effective and ensures safety. Oxygen system components are one example where a solvent compatible with oxygen and capable of removing fluorocarbon grease is needed. Electronic components and precision mechanical components can also be damaged by aggressive cleaning solvents.

  19. Optimal Management of the Critically Ill: Anaesthesia, Monitoring, Data Capture, and Point-of-Care Technological Practices in Ovine Models of Critical Care

    Directory of Open Access Journals (Sweden)

    Saul Chemonges

    2014-01-01

    Full Text Available Animal models of critical illness are vital in biomedical research. They provide possibilities for the investigation of pathophysiological processes that may not otherwise be possible in humans. In order to be clinically applicable, the model should simulate the critical care situation realistically, including anaesthesia, monitoring, sampling, utilising appropriate personnel skill mix, and therapeutic interventions. There are limited data documenting the constitution of ideal technologically advanced large animal critical care practices and all the processes of the animal model. In this paper, we describe the procedure of animal preparation, anaesthesia induction and maintenance, physiologic monitoring, data capture, point-of-care technology, and animal aftercare that has been successfully used to study several novel ovine models of critical illness. The relevant investigations are on respiratory failure due to smoke inhalation, transfusion related acute lung injury, endotoxin-induced proteogenomic alterations, haemorrhagic shock, septic shock, brain death, cerebral microcirculation, and artificial heart studies. We have demonstrated the functionality of monitoring practices during anaesthesia required to provide a platform for undertaking systematic investigations in complex ovine models of critical illness.

  20. Molecular simulations of electrolyte structure and dynamics in lithium-sulfur battery solvents

    Science.gov (United States)

    Park, Chanbum; Kanduč, Matej; Chudoba, Richard; Ronneburg, Arne; Risse, Sebastian; Ballauff, Matthias; Dzubiella, Joachim

    2018-01-01

    The performance of modern lithium-sulfur (Li/S) battery systems critically depends on the electrolyte and solvent compositions. For fundamental molecular insights and rational guidance of experimental developments, efficient and sufficiently accurate molecular simulations are thus in urgent need. Here, we construct a molecular dynamics (MD) computer simulation model of representative state-of-the art electrolyte-solvent systems for Li/S batteries constituted by lithium-bis(trifluoromethane)sulfonimide (LiTFSI) and LiNO3 electrolytes in mixtures of the organic solvents 1,2-dimethoxyethane (DME) and 1,3-dioxolane (DOL). We benchmark and verify our simulations by comparing structural and dynamic features with various available experimental reference systems and demonstrate their applicability for a wide range of electrolyte-solvent compositions. For the state-of-the-art battery solvent, we finally calculate and discuss the detailed composition of the first lithium solvation shell, the temperature dependence of lithium diffusion, as well as the electrolyte conductivities and lithium transference numbers. Our model will serve as a basis for efficient future predictions of electrolyte structure and transport in complex electrode confinements for the optimization of modern Li/S batteries (and related devices).

  1. SOLVENT EXTRACTION OF NEPTUNIUM

    Science.gov (United States)

    Butler, J.P.

    1958-08-12

    A process is described for the recovery of neptuniunn from dissolver solutions by solvent extraction. The neptunium containing solution should be about 5N, in nitric acid.and about 0.1 M in ferrous ion. The organic extracting agent is tributyl phosphate, and the neptuniunn is recovered from the organic solvent phase by washing with water.

  2. General surgery resident rotations in surgical critical care, trauma, and burns: what is optimal for residency training?

    Science.gov (United States)

    Napolitano, Lena M; Biester, Thomas W; Jurkovich, Gregory J; Buyske, Jo; Malangoni, Mark A; Lewis, Frank R

    2016-10-01

    There are no specific Accreditation Council for Graduate Medical Education General Surgery Residency Program Requirements for rotations in surgical critical care (SCC), trauma, and burn. We sought to determine the experience of general surgery residents in SCC, trauma, and burn rotations. Data analysis of surgical rotations of American Board of Surgery general surgery resident applicants (n = 7,299) for the last 8 years (2006 to 2013, inclusive) was performed through electronic applications to the American Board of Surgery Qualifying Examination. Duration (months) spent in SCC, trauma, and burn rotations, and postgraduate year (PGY) level were examined. The total months in SCC, trauma and burn rotations was mean 10.2 and median 10.0 (SD 3.9 months), representing approximately 16.7% (10 of 60 months) of a general surgery resident's training. However, there was great variability (range 0 to 29 months). SCC rotation duration was mean 3.1 and median 3.0 months (SD 2, min to max: 0 to 15), trauma rotation duration was mean 6.3 and median 6.0 months (SD 3.5, min to max: 0 to 24), and burn rotation duration was mean 0.8 and median 1.0 months (SD 1.0, min to max: 0 to 6). Of the total mean 10.2 months duration, the longest exposure was 2 months as PGY-1, 3.4 months as PGY-2, 1.9 months as PGY-3, 2.2 months as PGY-4 and 1.1 months as PGY-5. PGY-5 residents spent a mean of 1 month in SCC, trauma, and burn rotations. PGY-4/5 residents spent the majority of this total time in trauma rotations, whereas junior residents (PGY-1 to 3) in SCC and trauma rotations. There is significant variability in total duration of SCC, trauma, and burn rotations and PGY level in US general surgery residency programs, which may result in significant variability in the fund of knowledge and clinical experience of the trainee completing general surgery residency training. As acute care surgery programs have begun to integrate emergency general surgery with SCC, trauma, and burn rotations

  3. SOLVENT EXTRACTION PROCESS

    Science.gov (United States)

    Jonke, A.A.

    1957-10-01

    In improved solvent extraction process is described for the extraction of metal values from highly dilute aqueous solutions. The process comprises contacting an aqueous solution with an organic substantially water-immiscible solvent, whereby metal values are taken up by a solvent extract phase; scrubbing the solvent extract phase with an aqueous scrubbing solution; separating an aqueous solution from the scrubbed solvent extract phase; and contacting the scrubbed solvent phase with an aqueous medium whereby the extracted metal values are removed from the solvent phase and taken up by said medium to form a strip solution containing said metal values, the aqueous scrubbing solution being a mixture of strip solution and an aqueous solution which contains mineral acids anions and is free of the metal values. The process is particularly effective for purifying uranium, where one starts with impure aqueous uranyl nitrate, extracts with tributyl phosphate dissolved in carbon tetrachloride, scrubs with aqueous nitric acid and employs water to strip the uranium from the scrubbed organic phase.

  4. Optimization of Fast Critical Experiments to Reduce Nuclear Data Uncertainties in Support of a Fast Burner Reactor Design Concept

    Science.gov (United States)

    Stover, Tracy E., Jr.

    An optimization technique has been developed to select optimized experimental design specifications to produce data specifically designed to be assimilated to optimize a given reactor concept. Data from the optimized experiment is assimilated to generate posteriori uncertainties on the reactor concept's core attributes from which the design responses are computed. The reactor concept is then optimized with the new data to realize cost savings by reducing margin. The optimization problem iterates until an optimal experiment is found to maximize the savings. A new generation of innovative nuclear reactor designs, in particular fast neutron spectrum recycle reactors, are being considered for the application of closing the nuclear fuel cycle in the future. Safe and economical design of these reactors will require uncertainty reduction in basic nuclear data which are input to the reactor design. These data uncertainty propagate to design responses which in turn require the reactor designer to incorporate additional safety margin into the design, which often increases the cost of the reactor. Therefore basic nuclear data needs to be improved and this is accomplished through experimentation. Considering the high cost of nuclear experiments, it is desired to have an optimized experiment which will provide the data needed for uncertainty reduction such that a reactor design concept can meet its target accuracies or to allow savings to be realized by reducing the margin required due to uncertainty propagated from basic nuclear data. However, this optimization is coupled to the reactor design itself because with improved data the reactor concept can be re-optimized itself. It is thus desired to find the experiment that gives the best optimized reactor design. Methods are first established to model both the reactor concept and the experiment and to efficiently propagate the basic nuclear data uncertainty through these models to outputs. The representativity of the experiment

  5. SOLVENT EXTRACTION OF RUTHENIUM

    Science.gov (United States)

    Hyman, H.H.; Leader, G.R.

    1959-07-14

    The separation of rathenium from aqueous solutions by solvent extraction is described. According to the invention, a nitrite selected from the group consisting of alkali nitrite and alkaline earth nitrite in an equimolecular quantity with regard to the quantity of rathenium present is added to an aqueous solution containing ruthenium tetrantrate to form a ruthenium complex. Adding an organic solvent such as ethyl ether to the resulting mixture selectively extracts the rathenium complex.

  6. A framework for model-based optimization of bioprocesses under uncertainty: Identifying critical parameters and operating variables

    DEFF Research Database (Denmark)

    Morales Rodriguez, Ricardo; Meyer, Anne S.; Gernaey, Krist

    2011-01-01

    This study presents the development and application of a systematic model-based framework for bioprocess optimization, evaluated on a cellulosic ethanol production case study. The implementation of the framework involves the use of dynamic simulations, sophisticated uncertainty analysis (Monte...

  7. Solvent selection methodology for pharmaceutical processes: Solvent swap

    DEFF Research Database (Denmark)

    Papadakis, Emmanouil; Kumar Tula, Anjan; Gani, Rafiqul

    2016-01-01

    A method for the selection of appropriate solvents for the solvent swap task in pharmaceutical processes has been developed. This solvent swap method is based on the solvent selection method of Gani et al. (2006) and considers additional selection criteria such as boiling point difference, volati...

  8. NOVEL POLYMERIC MEMBRANE FOR DEHYDRATION OF ORGANIC SOLVENTS

    Science.gov (United States)

    Pervaporation has emerged as an economically viable alternative technology for dehydration of organic solvents, removal of organic compounds and organic/organic separations. Development of a membrane system with suitable flux and selectivity characteristics plays a critical role...

  9. Halogenated solvent remediation

    Science.gov (United States)

    Sorenson, Jr., Kent S.

    2008-11-11

    Methods for enhancing bioremediation of ground water contaminated with nonaqueous halogenated solvents are disclosed. An illustrative method includes adding an electron donor for microbe-mediated anaerobic reductive dehalogenation of the halogenated solvents, which electron donor enhances mass transfer of the halogenated solvents from residual source areas into the aqueous phase of the ground water. Illustrative electron donors include C.sub.2-C.sub.4 carboxylic acids and hydroxy acids, salts thereof, esters of C.sub.2-C.sub.4 carboxylic acids and hydroxy acids, and mixtures thereof, of which lactic acid, salts of lactic acid--such as sodium lactate, lactate esters, and mixtures thereof are particularly illustrative. The microbes are either indigenous to the ground water, or such microbes can be added to the ground water in addition to the electron donor.

  10. Separation by solvent extraction

    Science.gov (United States)

    Holt, Jr., Charles H.

    1976-04-06

    17. A process for separating fission product values from uranium and plutonium values contained in an aqueous solution, comprising adding an oxidizing agent to said solution to secure uranium and plutonium in their hexavalent state; contacting said aqueous solution with a substantially water-immiscible organic solvent while agitating and maintaining the temperature at from -1.degree. to -2.degree. C. until the major part of the water present is frozen; continuously separating a solid ice phase as it is formed; separating a remaining aqueous liquid phase containing fission product values and a solvent phase containing plutonium and uranium values from each other; melting at least the last obtained part of said ice phase and adding it to said separated liquid phase; and treating the resulting liquid with a new supply of solvent whereby it is practically depleted of uranium and plutonium.

  11. Comparison of Implicit and Explicit Solvent Models for the Calculation of Solvation Free Energy in Organic Solvents.

    Science.gov (United States)

    Zhang, Jin; Zhang, Haiyang; Wu, Tao; Wang, Qi; van der Spoel, David

    2017-03-14

    Quantitative prediction of physical properties of liquids is important for many applications. Computational methods based on either explicit or implicit solvent models can be used to approximate thermodynamics properties of liquids. Here, we evaluate the predictive power of implicit solvent models for solvation free energy of organic molecules in organic solvents. We compared the results calculated with four generalized Born (GB) models (GBStill, GBHCT, GBOBCI, and GBOBCII), the Poisson-Boltzmann (PB) model, and the density-based solvent model SMD with previous solvation free energy calculations (Zhang et al. J. Chem. Inf. 2015, 55, 1192-1201) and experimental data. The comparison indicates that both PB and GB give poor agreement with explicit solvent calculations and even worse agreement with experiments (root-mean-square deviation ≈ 15 kJ/mol). The main problem seems to be the prediction of the apolar contribution, which should include the solvent entropy. The quantum mechanical-based SMD model gives significantly better agreement with experimental data than do PB or GB, but it is not as good as explicit solvent calculation results. The dielectric constant ε of the solvent is found to be a powerful predictor for the polar contribution to the free energy in implicit models; however, the Onsager relation may not hold for realistic solvent, as suggested by explicit solvent and SMD calculations. From the comparison, we also find that with an optimization of the apolar contribution, the PB model gives slightly better agreement with experiments than the SMD model, whereas the correlation between the optimized GB models and experiments remains poor. Further optimization of the apolar contribution is needed for GB models to be able to treat solvents other than water.

  12. Hydrogenation of diesel aromatic compounds in supercritical solvent environment

    Directory of Open Access Journals (Sweden)

    E.P. Martins

    2000-09-01

    Full Text Available Reactions under supercritical conditions have been employed in many processes. Furthermore, an increasing number of commercial reactions have been conducted under supercritical or near critical conditions. These reaction conditions offer several advantages when compared to conditions in conventional catalytic processes in liquid-phase, gas-liquid interface, or even some gas-phase reactions. Basically, a supercritical solvent can diminish the reactant’s transport resistance from the bulk region to the catalyst surface due to enhancement of liquid diffusivity values and better solubility than those in different phases. Another advantage is that supercritical solvents permit prompt and easy changes in intermolecular properties in order to modify reaction parameters, such as conversion or selectivity, or even proceed with the separation of reaction products. Diesel fractions from petroleum frequently have larger than desirable quantities of aromatic compounds. Diesel hydrogenation is intended to decrease these quantities, i.e., to increase the quantity of paraffin present in this petroleum fraction. In this work, the hydrogenation of tetralin was studied as a model reaction for the aromatic hydrogenation process. A conventional gas-liquid-solid catalytic process was compared with that of supercritical carbon dioxide substrate under similar conditions. Additionally, an equilibrium conversion diagram was calculated for this reaction in a wide range of temperature and reactant ratios, so as to optimize the operational conditions and improve the results of subsequent experiments. An increase in the rate of reaction at 493 K in supercritical fluid, as compared to that in the conventional process, was observed.

  13. ONSITE SOLVENT RECOVERY

    Science.gov (United States)

    This study evaluated the product quality, waste reduction/pollution prevention, and economic aspects of three technologies for onsite solvent recovery. The technologies were (1) atmospheric batch distillation, (2) vacuum heat-pump distillation, and (3) low-emission vapor degreas...

  14. Organic solvent topical report

    Energy Technology Data Exchange (ETDEWEB)

    Cowley, W.L.

    1998-04-30

    This report is the technical basis for the accident and consequence analyses used in the Hanford Tank Farms Basis for Interim Operation. The report also contains the scientific and engineering information and reference material needed to understand the organic solvent safety issue. This report includes comments received from the Chemical Reactions Subcommittee of the Tank Advisory Panel.

  15. Organic solvent topical report

    Energy Technology Data Exchange (ETDEWEB)

    COWLEY, W.L.

    1999-05-13

    This report provides the basis for closing the organic solvent safety issue. Sufficient information is presented to conclude that risk posed by an organic solvent fire is within risk evaluation guidelines. This report updates information contained in Analysis of Consequences of Postulated Solvent Fires in Hanford Site Waste Tanks. WHC-SD-WM-CN-032. Rev. 0A (Cowley et al. 1996). However, this document will not replace Cowley et al (1996) as the primary reference for the Basis for Interim Operation (BIO) until the recently submitted BIO amendment (Hanson 1999) is approved by the US Department of Energy. This conclusion depends on the use of controls for preventing vehicle fuel fires and for limiting the use of flame cutting in areas where hot metal can fall on the waste surface.The required controls are given in the Tank Waste Remediation System Technical Safety Requirements (Noorani 1997b). This is a significant change from the conclusions presented in Revision 0 of this report. Revision 0 of this calcnote concluded that some organic solvent fire scenarios exceeded risk evaluation guidelines, even with controls imposed.

  16. Novel Power Flow Problem Solutions Method’s Based on Genetic Algorithm Optimization for Banks Capacitor Compensation Using an Fuzzy Logic Rule Bases for Critical Nodal Detections

    Directory of Open Access Journals (Sweden)

    Nasri Abdelfatah

    2011-01-01

    Full Text Available The Reactive power flow’s is one of the most electrical distribution systems problem wich have great of interset of the electrical network researchers, it’s  cause’s active power transmission reduction, power losses decreasing, and  the drop voltage’s increase. In this research we described the efficiency of the FLC-GAO approach to solve the optimal power flow (OPF combinatorial problem. The proposed approach employ tow algorithms, Fuzzy logic controller (FLC algorithm for critical nodal detection and gentic algorithm  optimization (GAO algorithm for optimal seizing capacitor.GAO method is more efficient in combinatory problem solutions. The proposed approach has been examined and tested on the standard IEEE 57-bus the resulats show the power loss minimization denhancement, voltage profile, and stability improvement. The proposed approach results have been compared to those that reported in the literature recently. The results are promising and show the effectiveness and robustness of the proposed approach.

  17. Optimization of Critical Hairpin Features Allows miRNA-based Gene Knockdown Upon Single-copy Transduction

    Directory of Open Access Journals (Sweden)

    Renier Myburgh

    2014-01-01

    Full Text Available Gene knockdown using micro RNA (miRNA-based vector constructs is likely to become a prominent gene therapy approach. It was the aim of this study to improve the efficiency of gene knockdown through optimizing the structure of miRNA mimics. Knockdown of two target genes was analyzed: CCR5 and green fluorescent protein. We describe here a novel and optimized miRNA mimic design called mirGE comprising a lower stem length of 13 base pairs (bp, positioning of the targeting strand on the 5′ side of the miRNA, together with nucleotide mismatches in upper stem positions 1 and 12 placed on the passenger strand. Our mirGE proved superior to miR-30 in four aspects: yield of targeting strand incorporation into RNA-induced silencing complex (RISC; incorporation into RISC of correct targeting strand; precision of cleavage by Drosha; and ratio of targeting strand over passenger strand. A triple mirGE hairpin cassette targeting CCR5 was constructed. It allowed CCR5 knockdown with an efficiency of over 90% upon single-copy transduction. Importantly, single-copy expression of this construct rendered transduced target cells, including primary human macrophages, resistant to infection with a CCR5-tropic strain of HIV. Our results provide new insights for a better knockdown efficiency of constructs containing miRNA. Our results also provide the proof-of-principle that cells can be rendered HIV resistant through single-copy vector transduction, rendering this approach more compatible with clinical applications.

  18. Optimal level activity of matrix metalloproteinases is critical for adult visual plasticity in the healthy and stroke-affected brain.

    Science.gov (United States)

    Pielecka-Fortuna, Justyna; Kalogeraki, Evgenia; Fortuna, Michal G; Löwel, Siegrid

    2015-11-26

    The ability of the adult brain to undergo plastic changes is of particular interest in medicine, especially regarding recovery from injuries or improving learning and cognition. Matrix metalloproteinases (MMPs) have been associated with juvenile experience-dependent primary visual cortex (V1) plasticity, yet little is known about their role in this process in the adult V1. Activation of MMPs is a crucial step facilitating structural changes in a healthy brain; however, upon brain injury, upregulated MMPs promote the spread of a lesion and impair recovery. To clarify these seemingly opposing outcomes of MMP-activation, we examined the effects of MMP-inhibition on experience-induced plasticity in healthy and stoke-affected adult mice. In healthy animals, 7-day application of MMP-inhibitor prevented visual plasticity. Additionally, treatment with MMP-inhibitor once but not twice following stroke rescued plasticity, normally lost under these conditions. Our data imply that an optimal level of MMP-activity is crucial for adult visual plasticity to occur.

  19. Optimization of critical factors to enhance polyhydroxyalkanoates (PHA) synthesis by mixed culture using Taguchi design of experimental methodology.

    Science.gov (United States)

    Venkata Mohan, S; Venkateswar Reddy, M

    2013-01-01

    Optimizing different factors is crucial for enhancement of mixed culture bioplastics (polyhydroxyalkanoates (PHA)) production. Design of experimental (DOE) methodology using Taguchi orthogonal array (OA) was applied to evaluate the influence and specific function of eight important factors (iron, glucose concentration, VFA concentration, VFA composition, nitrogen concentration, phosphorous concentration, pH, and microenvironment) on the bioplastics production. Three levels of factor (2(1) × 3(7)) variation were considered with symbolic arrays of experimental matrix [L(18)-18 experimental trails]. All the factors were assigned with three levels except iron concentration (2(1)). Among all the factors, microenvironment influenced bioplastics production substantially (contributing 81%), followed by pH (11%) and glucose concentration (2.5%). Validation experiments were performed with the obtained optimum conditions which resulted in improved PHA production. Good substrate degradation (as COD) of 68% was registered during PHA production. Dehydrogenase and phosphatase enzymatic activities were monitored during process operation. Copyright © 2012 Elsevier Ltd. All rights reserved.

  20. Actor-Critic Off-Policy Learning for Optimal Control of Multiple-Model Discrete-Time Systems.

    Science.gov (United States)

    Skach, Jan; Kiumarsi, Bahare; Lewis, Frank L; Straka, Ondrej

    2016-11-02

    In this paper, motivated by human neurocognitive experiments, a model-free off-policy reinforcement learning algorithm is developed to solve the optimal tracking control of multiple-model linear discrete-time systems. First, an adaptive self-organizing map neural network is used to determine the system behavior from measured data and to assign a responsibility signal to each of system possible behaviors. A new model is added if a sudden change of system behavior is detected from the measured data and the behavior has not been previously detected. A value function is represented by partially weighted value functions. Then, the off-policy iteration algorithm is generalized to multiple-model learning to find a solution without any knowledge about the system dynamics or reference trajectory dynamics. The off-policy approach helps to increase data efficiency and speed of tuning since a stream of experiences obtained from executing a behavior policy is reused to update several value functions corresponding to different learning policies sequentially. Two numerical examples serve as a demonstration of the off-policy algorithm performance.

  1. Improvement of Soybean Oil Solvent Extraction through Enzymatic Pretreatment

    OpenAIRE

    Grasso, F. V.; P. A. Montoya; Camusso, C. C.; Maroto, B. G.

    2012-01-01

    The purpose of this study is to evaluate multienzyme hydrolysis as a pretreatment option to improve soybean oil solvent extraction and its eventual adaptation to conventional processes. Enzymatic action causes the degradation of the cell structures that contain oil. Improvements in terms of extraction, yield, and extraction rate are expected to be achieved. Soybean flakes and collets were used as materials and hexane was used as a solvent. Temperature, pH, and incubation time were optimized a...

  2. Elucidating the Solvation Structure and Dynamics of Lithium Polysulfides Resulting from Competitive Salt and Solvent Interactions

    Energy Technology Data Exchange (ETDEWEB)

    Rajput, Nav Nidhi; Murugesan, Vijayakumar; Shin, Yongwoo; Han, Kee Sung; Lau, Kah Chun; Chen, Junzheng; Liu, Jun; Curtiss, Larry A.; Mueller, Karl T.; Persson, Kristin A.

    2017-04-10

    Fundamental molecular level understanding of functional properties of liquid solutions provides an important basis for designing optimized electrolytes for numerous applica-tions. In particular, exhaustive knowledge of solvation structure, stability and transport properties is critical for developing stable electrolytes for fast charging and high energy density next-generation energy storage systems. Here we report the correlation between solubility, solvation structure and translational dynamics of a lithium salt (Li-TFSI) and polysulfides species using well-benchmarked classical molecular dynamics simulations combined with nuclear magnetic resonance (NMR). It is observed that the polysulfide chain length has a significant effect on the ion-ion and ion-solvent interaction as well as on the diffusion coefficient of the ionic species in solution. In particular, extensive cluster formation is observed in lower order poly-sulfides (Sx2-; x≤4), whereas the longer polysulfides (Sx2-; x>4) show high solubility and slow dynamics in the solu-tion. It is observed that optimal solvent/salt ratio is essen-tial to control the solubility and conductivity as the addi-tion of Li salt increases the solubility but decreases the mo-bility of the ionic species. This work provides a coupled theoretical and experimental study of bulk solvation struc-ture and transport properties of multi-component electro-lyte systems, yielding design metrics for developing optimal electrolytes with improved stability and solubility.

  3. Essential roles of protein-solvent many-body correlation in solvent-entropy effect on protein folding and denaturation: Comparison between hard-sphere solvent and water

    Energy Technology Data Exchange (ETDEWEB)

    Oshima, Hiraku; Kinoshita, Masahiro, E-mail: kinoshit@iae.kyoto-u.ac.jp [Institute of Advanced Energy, Kyoto University, Uji, Kyoto 611-0011 (Japan)

    2015-04-14

    In earlier works, we showed that the entropic effect originating from the translational displacement of water molecules plays the pivotal role in protein folding and denaturation. The two different solvent models, hard-sphere solvent and model water, were employed in theoretical methods wherein the entropic effect was treated as an essential factor. However, there were similarities and differences in the results obtained from the two solvent models. In the present work, to unveil the physical origins of the similarities and differences, we simultaneously consider structural transition, cold denaturation, and pressure denaturation for the same protein by employing the two solvent models and considering three different thermodynamic states for each solvent model. The solvent-entropy change upon protein folding/unfolding is decomposed into the protein-solvent pair (PA) and many-body (MB) correlation components using the integral equation theories. Each component is further decomposed into the excluded-volume (EV) and solvent-accessible surface (SAS) terms by applying the morphometric approach. The four physically insightful constituents, (PA, EV), (PA, SAS), (MB, EV), and (MB, SAS), are thus obtained. Moreover, (MB, SAS) is discussed by dividing it into two factors. This all-inclusive investigation leads to the following results: (1) the protein-water many-body correlation always plays critical roles in a variety of folding/unfolding processes; (2) the hard-sphere solvent model fails when it does not correctly reproduce the protein-water many-body correlation; (3) the hard-sphere solvent model becomes problematic when the dependence of the many-body correlation on the solvent number density and temperature is essential: it is not quite suited to studies on cold and pressure denaturating of a protein; (4) when the temperature and solvent number density are limited to the ambient values, the hard-sphere solvent model is usually successful; and (5) even at the ambient

  4. Solvent Extraction and Characterization of Neutral Lipids in Oocystis sp.

    Directory of Open Access Journals (Sweden)

    Renil eAnthony

    2015-01-01

    Full Text Available Microalgae are a favorable feedstock for bioproducts and biofuels due to their high oil content, fast growth rates and low resource demands. Solvent lipid extraction efficiency from microalgae is dependent on algal strain and the extraction solvent. Four non-polar extraction solvents were evaluated for the recovery of neutral cellular lipids from microalgae Oocystis sp. (UTEX LB2396. Methylene chloride, hexane, diethyl ether, and cyclohexane were selected as the extraction solvents. All solvent extracts contained hexadecanoic acid, linoleic acid and linolenic acid; accounting for 70% of total lipid content with a proportional wt% composition of the three fatty acids, except for the hexane extracts that showed only hexadecanoic acid and linoleic acid. While not statistically differentiated, methylene chloride proved to be the most effective solvent for Oocystis sp. among the four solvents tested with a total average neutral lipid recovery of 0.25% of dry weight followed by diethyl ether (0.18%, cyclohexane (0.14% and hexane (0.11%. This research presents a simple methodology to optimize the selection of lipid specific extraction solvents for the microalgal strain selected.

  5. Hydrogen recovery by novel solvent systems. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Shinnar, R.; Ludmer, Z.; Ullmann, A.

    1991-08-01

    The objective of this work is to develop a novel method for purification of hydrogen from coal-derived synthesis gas. The study involved a search for suitable mixtures of solvents for their ability to separate hydrogen from the coal derived gas stream in significant concentration near their critical point of miscibility. The properties of solvent pairs identified were investigated in more detail to provide data necessary for economic evaluation and process development.

  6. Organic solvents and cancer.

    Science.gov (United States)

    Lynge, E; Anttila, A; Hemminki, K

    1997-05-01

    Epidemiologic evidence on the relationship between organic solvents and cancer is reviewed. In the 1980s, more than a million persons were potentially exposed to some specific solvents in the United States; in Canada, 40 percent of male cancer patients in Montreal had experienced exposure to solvents; in the Finnish population, one percent was regularly exposed. There is evidence for increased risks of cancer following exposure to: trichloroethylene (for the liver and biliary tract and for non-Hodgkin's lymphomas); tetrachloroethylene (for the esophagus and cervix--although confounding by smoking, alcohol, and sexual habits cannot be excluded--and non-Hodgkin's lymphoma); and carbon tetrachloride (lymphohematopoietic malignancies). An excess risk of liver and biliary tract cancers was suggested in the cohort with the high exposure to methylene chloride, but not found in the other cohorts where an excess risk of pancreatic cancer was suggested. 1,1,1-trichloroethane has been used widely, but only a few studies have been done suggesting a risk of multiple myeloma. A causal association between exposure to benzene and an increased risk of leukemia is well-established, as well as a suggested risk of lung and nasopharynx cancer in a Chinese cohort. Increased risks of various gastrointestinal cancers have been suggested following exposure to toluene. Two informative studies indicated an increased risk of lung cancer, not supported by other studies. Increased risks of lymphohematopoietic malignancies have been reported in some studies of persons exposed to toluene or xylene, but not in the two most informative studies on toluene. Occupation as a painter has consistently been associated with a 40 percent increased risk of lung cancer. (With the mixed exposures, however, it is not possible to identify the specific causative agent[s].) A large number of studies of workers exposed to styrene have evidenced no consistent excess risk of all lymphohematopoietic malignancies

  7. Solvent effects in chemistry

    CERN Document Server

    Buncel, Erwin

    2015-01-01

    This book introduces the concepts, theory and experimental knowledge concerning solvent effects on the rate and equilibrium of chemical reactions of all kinds.  It begins with basic thermodynamics and kinetics, building on this foundation to demonstrate how a more detailed understanding of these effects may be used to aid in determination of reaction mechanisms, and to aid in planning syntheses. Consideration is given to theoretical calculations (quantum chemistry, molecular dynamics, etc.), to statistical methods (chemometrics), and to modern day concerns such as ""green"" chemistry, where ut

  8. Allosteric changes in solvent accessibility observed in thrombin upon active site occupation.

    Science.gov (United States)

    Croy, Carrie Hughes; Koeppe, Julia R; Bergqvist, Simon; Komives, Elizabeth A

    2004-05-11

    The solvent accessibility of thrombin in its substrate-free and substrate-bound forms has been compared by amide hydrogen/deuterium (H/(2)H) exchange. The optimized inhibitor peptide dPhe-Pro-Arg chloromethyl ketone (PPACK) was used to simulate the substrate-bound form of thrombin. These studies were motivated by the lack of observed changes in the active site of thrombin in the crystal structure of the thrombin-thrombomodulin complex. This result appeared to contradict amide exchange studies on the thrombin-thrombomodulin complex that suggested subtle changes occur in the active site loops upon thrombomodulin binding. Our results show that two active site loops, residues 214-222 and residues 126-132, undergo decreases in solvent accessibility due to steric contacts with PPACK substrate. However, we also observe two regions outside the active site undergoing solvent protection upon substrate binding. The first region corresponds to anion binding exosite 1, and the second is a beta-strand-containing loop which runs through the core of the molecule and contains Trp141 which makes critical contacts with anion binding exosite 1. These results indicate two pathways of allosteric change that connect the active site to the distal anion binding exosite 1.

  9. Optimal strategies for VOC emission abatement produced by solvent evaporation. The Italian case study; Strategie ottimali per la riduzione delle emissioni di composti organici volatili da uso di solventi: il caso italiano

    Energy Technology Data Exchange (ETDEWEB)

    Vetrella, G.; Cirillo, M.C. [ENEA, Centro Ricerche Casaccia, Rome (Italy). Dipt. Ambiente

    1998-07-01

    This work analyses technologies and costs of VOC (volatile organic compounds) abatement in the activities which belong to the solvent evaporation sector, and then it singles out the most successful strategies from the costs point of view to reduce the sector emissions on the base of fixed abatement objectives. The Italian case is discussed. [Italian] Il lavoro analizza tecnologie e costi di abbattimento dei COV (composti organici volatili) nel settore evaporazione solventi, e individua la strategia piu' efficace dal punto di vista dei costi per ridurre le emissioni del settore sulla base di prefissati obiettivi di abbattimento. Analizza la situazione italiana.

  10. Solvent effects and chemical reactivity

    National Research Council Canada - National Science Library

    Tapia, Orlando; Bertrán, J

    1996-01-01

    ... original contributions from a selected group of distinguished researchers that are actively working in the theory and practical applications of solvent effects and chemical reactions. The importance...

  11. Sharp Interface Tracking in Rotating Microflows of Solvent Extraction

    Energy Technology Data Exchange (ETDEWEB)

    Glimm, James [Stony Brook Univ., NY (United States); Almeida, Valmor de [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Jiao, Xiangmin [Stony Brook Univ., NY (United States); Sims, Brett [City Univ. (CUNY), NY (United States). Borough of Manhattan Community College; Li, Xaiolin [Stony Brook Univ., NY (United States)

    2013-01-08

    The objective of this project is to develop a specialized sharp interface tracking simulation capability for predicting interaction of micron-sized drops and bubbles in rotating flows relevant to optimized design of contactor devices used in solvent extraction processes of spent nuclear fuel reprocessing. The primary outcomes of this project include the capability to resolve drops and bubbles micro-hydrodynamics in solvent extraction contactors, determining from first principles continuum fluid mechanics how micro-drops and bubbles interact with each other and the surrounding shearing fluid for realistic flows. In the near term, this effort will play a central role in providing parameters and insight into the flow dynamics of models that average over coarser scales, say at the millimeter unit length. In the longer term, it will prove to be the platform to conduct full-device, detailed simulations as parallel computing power reaches the exaflop level. The team will develop an accurate simulation tool for flows containing interacting droplets and bubbles with sharp interfaces under conditions that mimic those found in realistic contactor operations. The main objective is to create an off-line simulation capability to model drop and bubble interactions in a domain representative of the averaged length scale. The technical approach is to combine robust interface tracking software, subgrid modeling, validation quality experiments, powerful computational hardware, and a team with simulation modeling, physical modeling and technology integration experience. Simulations will then fully resolve the microflow of drops and bubbles at the microsecond time scale. This approach is computationally intensive but very accurate in treating important coupled physical phenomena in the vicinity of interfaces. The method makes it possible to resolve spatial scales smaller than the typical distance between bubbles and to model some non-equilibrium thermodynamic features such as finite

  12. Maternal death inquiry and response in India - the impact of contextual factors on defining an optimal model to help meet critical maternal health policy objectives

    Directory of Open Access Journals (Sweden)

    Kalter Henry D

    2011-11-01

    Full Text Available Abstract Background Maternal death reviews have been utilized in several countries as a means of identifying social and health care quality issues affecting maternal survival. From 2005 to 2009, a standardized community-based maternal death inquiry and response initiative was implemented in eight Indian states with the aim of addressing critical maternal health policy objectives. However, state-specific contextual factors strongly influenced the effort's success. This paper examines the impact and implications of the contextual factors. Methods We identified community, public health systems and governance related contextual factors thought to affect the implementation, utilization and up-scaling of the death inquiry process. Then, according to selected indicators, we documented the contextual factors' presence and their impact on the process' success in helping meet critical maternal health policy objectives in four districts of Rajasthan, Madhya Pradesh and West Bengal. Based on this assessment, we propose an optimal model for conducting community-based maternal death inquiries in India and similar settings. Results The death inquiry process led to increases in maternal death notification and investigation whether civil society or government took charge of these tasks, stimulated sharing of the findings in multiple settings and contributed to the development of numerous evidence-based local, district and statewide maternal health interventions. NGO inputs were essential where communities, public health systems and governance were weak and boosted effectiveness in stronger settings. Public health systems participation was enabled by responsive and accountable governance. Communities participated most successfully through India's established local governance Panchayat Raj Institutions. In one instance this led to the development of a multi-faceted intervention well-integrated at multiple levels. Conclusions The impact of several contextual

  13. Stability and selectivity of alkaline proteases in hydrophilic solvents

    DEFF Research Database (Denmark)

    Pedersen, Lars Haastrup; Ritthitham, Sinthuwat; Pleissner, Daniel

    2008-01-01

    Hydrophilic, organic solvents can be used as co-solvents with water to produce one phase systems sustaining optimal mass transfer of substrates and products of mixed polarity in biocatalysed processes. At concentrations below 50 % hydrophilic solvents can even have a stabilising effect on alkaline...... active molecules and carriers, and in synthesis of carbohydrate derivatives with designed functional properties.  When it comes to regio-selectivity of alkaline proateses on carbohydrates both the properties of the particular enzyme and the influence of the solvent is determining for the position...... [10]. This way acylation of a secondary hydroxyl group situated on the glucose moiety of sucrose was obtained. The initial reaction rate of acylation was not effected by the fatty acid chain length of the acyl donor. The half life of the enzyme in de-ioniset water was 4 minutes whereas in 100% DMF...

  14. Parallel Generalized Born Implicit Solvent Calculations with NAMD.

    Science.gov (United States)

    Tanner, David E; Chan, Kwok-Yan; Phillips, James C; Schulten, Klaus

    2011-11-08

    Accurate electrostatic descriptions of aqueous solvent are critical for simulation studies of bio-molecules, but the computational cost of explicit treatment of solvent is very high. A computationally more feasible alternative is a generalized Born implicit solvent description which models polar solvent as a dielectric continuum. Unfortunately, the attainable simulation speedup does not transfer to the massive parallel computers often employed for simulation of large structures. Longer cutoff distances, spatially heterogenous distribution of atoms and the necessary three-fold iteration over atom-pairs in each timestep combine to challenge efficient parallel performance of generalized Born implicit solvent algorithms. Here we report how NAMD, a parallel molecular dynamics program, meets the challenge through a unique parallelization strategy. NAMD now permits efficient simulation of large systems whose slow conformational motions benefit most from implicit solvent descriptions due to the inherent low viscosity. NAMD's implicit solvent performance is benchmarked and then illustrated in simulating the ratcheting Escherichia coli ribosome involving ~250,000 atoms.

  15. Solvent Induced Conformational Kinetics (SICK)

    NARCIS (Netherlands)

    Jonkman, Leffert; Kommandeur, Jan

    1970-01-01

    Specific conformations of molecules may be induced by the solvent when a large free volume is associated with the oonformational change. The conformational energy barrier is then a property of the solvent, rather than of the molecule. Such effects are reported for several substituted

  16. SOLVENT EXTRACTION OF URANIUM VALUES

    Science.gov (United States)

    Feder, H.M.; Ader, M.; Ross, L.E.

    1959-02-01

    A process is presented for extracting uranium salt from aqueous acidic solutions by organic solvent extraction. It consists in contacting the uranium bearing solution with a water immiscible dialkylacetamide having at least 8 carbon atoms in the molecule. Mentioned as a preferred extractant is dibutylacetamide. The organic solvent is usually used with a diluent such as kerosene or CCl/sub 4/.

  17. Solvent Size Dependent Structure Of Diblock Copolymer Micelles In N-alkane

    Science.gov (United States)

    Lee, Sangho; Heo, Tae-Young; Choi, Soo-Hyung

    Block copolymers can self-assemble into micelles in selective solvents. Theoretical description for the micelle structure is described the balance between core block stretching and core block-solvent interaction with the assumption that the core is melt state. So, core block was stretched and solvent entropy effect(e.g.solvent penetration into core)was simplified at the theoretical models. However, we observed PS-PEP micelle in squalane that the core block was nearly fully relaxed. In this study, we investigate the micelle structure as a function of solvent size. Here, we use Poly(styrene-b-ethylene-alt-propylene) in selective solvent such as n-alkanes. Solvents are favorable for PEP corona block and unfavorable PS core block. As solvent size decreases, solvent easily can penetrate into core, however, interaction parameter increases systematic. Critical micelle temperature(CMT) and detailed micelle structure were measured by Small-Angle X-ray Scattering. Interestingly, we observed that the CMT decreases as solvent size decreases. The core block is fully relaxed by comparing with core radius and 20,PS. Almost each structure data overlapped as a function of CMT-T. This results show that block copolymer micelle can be controlled by solvent size and thus solvent entropy effect Ministry of Trade, Industry and Energy, Korea Evaluation Institute of Industrial Technology, Pohang Accelerator Laboratory (4C beam line).

  18. Production of thermostable and organic solvent-tolerant alkaline ...

    African Journals Online (AJOL)

    An alkaliphilic bacterium producing organic solvent-tolerant and thermostable alkaline protease was isolated from poultry litter site and identified as Bacillus coagulans PSB-07. Protease production under different submerged fermentation conditions were investigated with the aim of optimizing yield of enzyme. B. coagulans ...

  19. Critical assessment and optimization of phase diagrams and thermodynamic properties of RE–Zn systems-part I: Sc–Zn, La–Zn, Ce–Zn, Pr–Zn, Nd–Zn, Pm–Zn and Sm–Zn

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Zhijun; Pelton, Arthur D.

    2015-08-25

    Highlights: • All phase diagram and thermodynamic data critically assessed for 7 (10) binary systems. • All phases described by optimized thermodynamic models. • All systems assessed simultaneously thereby exploiting trends in rare earth series. • Results will be combined with RE–Zn, Mg–Zn and ternary optimizations. • Final product will be a database for multicomponent Mg–RE–Zn systems. - Abstract: All available phase diagram and thermodynamic data for the Sc–Zn, La–Zn, Ce–Zn, Pr–Zn, Nd–Zn, Pm–Zn and Sm–Zn systems have been collected and critically assessed. Optimized model parameters for the thermodynamic properties of all phases have been obtained. Trends in the properties of the rare earth (RE)–Zn systems as one traverses the rare earth series have been exploited for purposes of estimating missing data and for checking existing data for consistency.

  20. Flux growth of baryte-type BaSO4 from chloridic alkaline metal solvents

    NARCIS (Netherlands)

    Ehrentraut, D.; Pollnau, Markus

    2002-01-01

    The growth of BaSO4 from high-temperature fluxes of both chloridic alkaline metal and alkaline-earth metal solvents has been investigated. Two binary alkaline-metal solvent systems containing LiCl and the additive ternary system with CsCl–KCl–NaCl where optimized with respect to solute concentration

  1. Selection and design of solvents

    DEFF Research Database (Denmark)

    Gani, Rafiqul

    and design of solvents will be presented together with application examples. The selection problem is defined as finding known chemicals that match the desired functions of a solvent for a specified set of applications. The design problem is defined as finding the molecular structure (or mixture of molecules....... With increasing interest on issues such as waste, sustainability, environmental impact and green chemistry, the selection and design of solvents have become important problems that need to be addressed during chemical product-process design and development. Systematic methods and tools suitable for selection...

  2. Acetone-based cellulose solvent.

    Science.gov (United States)

    Kostag, Marc; Liebert, Tim; Heinze, Thomas

    2014-08-01

    Acetone containing tetraalkylammonium chloride is found to be an efficient solvent for cellulose. The addition of an amount of 10 mol% (based on acetone) of well-soluble salt triethyloctylammonium chloride (Et3 OctN Cl) adjusts the solvent's properties (increases the polarity) to promote cellulose dissolution. Cellulose solutions in acetone/Et3 OctN Cl have the lowest viscosity reported for comparable aprotic solutions making it a promising system for shaping processes and homogeneous chemical modification of the biopolymer. Recovery of the polymer and recycling of the solvent components can be easily achieved. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Handbook of organic solvent properties

    CERN Document Server

    Smallwood, Ian

    2012-01-01

    The properties of 72 of the most commonly used solvents are given, tabulated in the most convenient way, making this book a joy for industrial chemists to use as a desk reference. The properties covered are those which answer the basic questions of: Will it do the job? Will it harm the user? Will it pollute the air? Is it easy to handle? Will it pollute the water? Can it be recovered or incinerated? These are all factors that need to be considered at the early stages of choosing a solvent for a new product or process.A collection of the physical properties of most commonly used solvents, their

  4. Caustic-Side Solvent Extraction Solvent-Composition Recommendation

    Energy Technology Data Exchange (ETDEWEB)

    Klatt, L.N.

    2002-05-09

    The U.S. Department of Energy has selected caustic-side solvent extraction as the preferred cesium removal technology for the treatment of high-level waste stored at the Savannah River Site. Data for the solubility of the extractant, calix[4]arene-bis(tert-octyl benzo-crown-6), acquired and reported for the Salt Processing Program down-select decision, showed the original solvent composition to be supersaturated with respect to the extractant. Although solvent samples have been observed for approximately 1 year without any solids formation, work was completed to define a new solvent composition that was thermodynamically stable with respect to solids formation and to expand the operating temperature with respect to third-phase formation. Chemical and physical data as a function of solvent component concentrations were collected. The data included calix[4]arene-bis(tert-octyl benzo-crown-6) solubility; cesium distribution ratio under extraction, scrub, and strip conditions; flow sheet robustness; temperature range of third-phase formation; dispersion numbers for the solvent against waste simulant, scrub and strip acids, and sodium hydroxide wash solutions; solvent density; viscosity; and surface and interfacial tension. These data were mapped against a set of predefined performance criteria. The composition of 0.007 M calix[4]arene-bis(tert-octyl benzo-crown-6), 0.75 M 1-(2,2,3,3-tetrafluoropropoxy)-3-(4-sec-butylphenoxy)-2-propanol, and 0.003 M tri-n-octylamine in the diluent Isopar{reg_sign} L provided the best match between the measured properties and the performance criteria. Therefore, it is recommended as the new baseline solvent composition.

  5. Fission product solvent extraction

    Energy Technology Data Exchange (ETDEWEB)

    Moyer, B.A.; Bonnesen, P.V.; Sachleben, R.A. [and others

    1998-02-01

    Two main objectives concerning removal of fission products from high-level tank wastes will be accomplished in this project. The first objective entails the development of an acid-side Cs solvent-extraction (SX) process applicable to remediation of the sodium-bearing waste (SBW) and dissolved calcine waste (DCW) at INEEL. The second objective is to develop alkaline-side SX processes for the combined removal of Tc, Cs, and possibly Sr and for individual separation of Tc (alone or together with Sr) and Cs. These alkaline-side processes apply to tank wastes stored at Hanford, Savannah River, and Oak Ridge. This work exploits the useful properties of crown ethers and calixarenes and has shown that such compounds may be economically adapted to practical processing conditions. Potential benefits for both acid- and alkaline-side processing include order-of-magnitude concentration factors, high rejection of bulk sodium and potassium salts, and stripping with dilute (typically 10 mM) nitric acid. These benefits minimize the subsequent burden on the very expensive vitrification and storage of the high-activity waste. In the case of the SRTALK process for Tc extraction as pertechnetate anion from alkaline waste, such benefits have now been proven at the scale of a 12-stage flowsheet tested in 2-cm centrifugal contactors with a Hanford supernatant waste simulant. SRTALK employs a crown ether in a TBP-modified aliphatic kerosene diluent, is economically competitive with other applicable separation processes being considered, and has been successfully tested in batch extraction of actual Hanford double-shell slurry feed (DSSF).

  6. Impact of Solvents Treatment on the Wettability of Froth Solids

    Science.gov (United States)

    Yang, Fan

    The purpose of this study is to investigate the impact of solvent addition to bitumen froth on the wettability of froth solids. The wettability of solids determines the transportation/partitioning of the solids between phases, which in turn affects the solids and water rejection in a Clark hot water extraction process (CHWE). The impact of solvents treatment on the wettability of froth solids was studied using both a model system and a real bitumen froth system. The vulnerabilities of four kinds of model minerals to hydrocarbon contamination/wettability alteration in different solvents were compared and discussed by considering solvent composition and mineral types. The wettability of solids extracted from the industrial froth using different solvents was also compared. The XRD analysis on these solids confirmed the partitioning behavior of solids observed in model solids system. The results from this study indicate that the composition of paraffinic/aromatic solvent in an industrial froth treatment process could be tailor-optimized to achieve a better solids/water rejection.

  7. Practical Approaches to Green Solvents

    National Research Council Canada - National Science Library

    Joseph M. DeSimone

    2002-01-01

    Solvents are widely used in commercial manufacturing and service industries. Despite abundant precaution, they inevitably contaminate our air, land, and water because they are difficult to contain and recycle...

  8. ON-SITE SOLVENT RECOVERY

    Science.gov (United States)

    This study evaluated the product quality, waste reduction/pollution prevention, and economic aspects of three technologies for onsite solvent recovery: atmospheric batch distillation, vacuum heat-pump distillation, and low-emission vapor degreasing. The atmospheric and vacuum ...

  9. Hansen Cleaning Solvent Research Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Environmental regulation will force current baseline  precision cleaning solvent (AK-225) to be phased out starting 2015. We plan to develop  a new...

  10. Deacidification of Soybean Oil Combining Solvent Extraction and Membrane Technology

    OpenAIRE

    Fornasero, M. L.; Marenchino, R. N.; C. L. Pagliero

    2013-01-01

    The aim of this work was to study the removal of free fatty acids (FFAs) from soybean oil, combining solvent extraction (liquid-liquid) for the separation of FFAs from the oil and membrane technology to recover the solvent through nanofiltration (NF). Degummed soybean oil containing 1.05 ± 0.10% w/w FFAs was deacidified by extraction with ethanol. Results obtained in the experiences of FFAs extraction from oil show that the optimal operating conditions are the following: 1.8 : 1 w : w ethanol...

  11. Optimization of non-aqueous electrolytes for Primary lithium/air batteries operated in Ambient Enviroment

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Wu; Xiao, Jie; Zhang, Jian; Wang, Deyu; Zhang, Jiguang

    2009-07-07

    The selection and optimization of non-aqueous electrolytes for ambient operations of lithium/air batteries has been studied. Organic solvents with low volatility and low moisture absorption are necessary to minimize the change of electrolyte compositions and the reaction between lithium anode and water during discharge process. It is critical to make the electrolytes with high polarity so that it can reduce wetting and flooding of carbon based air electrode and lead to improved battery performance. For ambient operations, the viscosity, ionic conductivity, and oxygen solubility of the electrolyte are less important than the polarity of organic solvents once the electrolyte has reasonable viscosity, conductivity, and oxygen solubility. It has been found that PC/EC mixture is the best solvent system and LiTFSI is the most feasible salt for ambient operations of Li/air batteries. Battery performance is not very sensitive to PC/EC ratio or salt concentration.

  12. A computer-aided molecular design framework for crystallization solvent design

    DEFF Research Database (Denmark)

    Karunanithi, Arunprakash T.; Achenie, Luke E.K.; Gani, Rafiqul

    2006-01-01

    One of the key decisions in designing solution crystallization processes is the selection of solvents. In this paper, we present a computer-aided molecular design (CAMD) framework for the design and selection of solvents and/or anti-solvents for solution crystallization. The CAMD problem......, property requirements such as solubility, crystal morphology, flashpoint, toxicity, viscosity, normal boiling and melting point are posed as constraints. All the properties are estimated using group contribution methods. The MINLP model is then solved using a decomposition approach to obtain optimal...... solvent molecules. Solvent design and selection for two types of solution crystallization processes namely cooling crystallization and drowning out crystallization are presented. In the first case study, the design of single compound solvent for crystallization of ibuprofen, which is an important...

  13. Solvent-Assisted Desorption of 2,5-Lutidine from Polyurethane Films.

    Science.gov (United States)

    Boyne, Devon A; Varady, Mark J; Lambeth, Robert H; Eikenberg, Janlyn H; Bringuier, Stefan A; Pearl, Thomas P; Mantooth, Brent A

    2018-02-08

    A fundamental understanding of chemical interactions and transport mechanisms that result from introducing multiple chemical species into a polymer plays a key role in the development and optimization of membranes, coatings, and decontamination formulations. In this study, we explore the solvent-assisted desorption of a penetrant (2,5-lutidine) in polyurethane with aprotic (acetonitrile) and protic (methanol) solvents. Chemical interactions between solvent, penetrant, and polymer functional groups are characterized via time-resolved Fourier transform infrared spectroscopy (FTIR) during single and multicomponent exposures. For both solvents, an increase in the extraction rate of the penetrant is observed when the solvent is applied during desorption. Inspection of the FTIR spectra reveals two potential mechanisms that facilitate the enhanced desorption rate: (1) penetrant/solvent competition for hydrogen donor groups on the polymer backbone and (2) disruption of the self-interaction (cohesive forces) between neighboring polymer chains. Finally, the aprotic solvent is found to generate an order of magnitude greater desorption rate of the penetrant, which is attributed to a greater disruption of the self-interaction during penetrant desorption compared to the protic solvent and the inability of an aprotic solvent to form larger and potentially slower penetrant-solvent complexes.

  14. Solvents interactions with thermochromic print

    Directory of Open Access Journals (Sweden)

    Mirela Rožić

    2017-12-01

    Full Text Available In this study, the interactions between different solvents (benzene, acetone, cyclohexanone, various alcohols and water and thermochromic printing ink were investigated. Thermochromic printing ink was printed on metal surface. Components of thermochromic printing inks are polymeric microcapsules and classic yellow offset printing ink. Below its activation temperature, dye and developer within the microcapsules form a blue coloured complex. Therefore, thermochromic print is green. By heating above the activation temperature, blue colour of the complex turns into the leuco dye colourless state and the green colour of the prints turns into the yellow colour of the classic offset pigment. The results of the interaction with various solvents show that the thermochromic print is stable in all tested solvents except in ethanol, acetone and cyclohexanone. In ethanol, the green colour of the print becomes yellow. SEM analysis shows that microcapsules are dissolved. In acetone and cyclohexanone, the green colour of the print turns into blue, and the microcapsules become significantly more visible. Thus, the yellow pigment interacts with examined ketones. Based on the obtained interactions it can be concluded that the microcapsules have more polar nature than the classical pigment particles. Solvent-thermocromic print interactions were analysed using Hansen solubility parameters that rank the solvents based on their estimated interaction capabilities.

  15. Multiple sclerosis and organic solvents

    DEFF Research Database (Denmark)

    Mortensen, J T; Brønnum-Hansen, Henrik; Rasmussen, K

    1998-01-01

    We investigated a possible causal relation between exposure to organic solvents in Danish workers (housepainters, typographers/printers, carpenters/cabinetmakers) and onset of multiple sclerosis. Data on men included in the Danish Multiple Sclerosis Register (3,241 men) were linked with data from......, and butchers. Over a follow-up period of 20 years, we observed no increase in the incidence of multiple sclerosis among men presumed to be exposed to organic solvents. It was not possible to obtain data on potential confounders, and the study design has some potential for selection bias. Nevertheless......, the study does not support existing hypotheses regarding an association between occupational exposure to organic solvents and multiple sclerosis....

  16. Solvent extraction of gold using ionic liquid based process

    Science.gov (United States)

    Makertihartha, I. G. B. N.; Zunita, Megawati; Rizki, Z.; Dharmawijaya, P. T.

    2017-01-01

    In decades, many research and mineral processing industries are using solvent extraction technology for metal ions separation. Solvent extraction technique has been used for the purification of precious metals such as Au and Pd, and base metals such as Cu, Zn and Cd. This process uses organic compounds as solvent. Organic solvents have some undesired properties i.e. toxic, volatile, excessive used, flammable, difficult to recycle, low reusability, low Au recovery, together with the problems related to the disposal of spent extractants and diluents, even the costs associated with these processes are relatively expensive. Therefore, a lot of research have boosted into the development of safe and environmentally friendly process for Au separation. Ionic liquids (ILs) are the potential alternative for gold extraction because they possess several desirable properties, such as a the ability to expanse temperature process up to 300°C, good solvent properties for a wide range of metal ions, high selectivity, low vapor pressures, stability up to 200°C, easy preparation, environmentally friendly (commonly called as "green solvent"), and relatively low cost. This review paper is focused in investigate of some ILs that have the potentials as solvent in extraction of Au from mineral/metal alloy at various conditions (pH, temperature, and pressure). Performances of ILs extraction of Au are studied in depth, i.e. structural relationship of ILs with capability to separate Au from metal ions aggregate. Optimal extraction conditon in order to gain high percent of Au in mineral processing is also investigated.

  17. Development of suitable solvent system for downstream processing of biopolymer pullulan using response surface methodology.

    Directory of Open Access Journals (Sweden)

    Anirban Roy Choudhury

    Full Text Available Downstream processing is an important aspect of all biotechnological processes and has significant implications on quality and yield of the final product. Several solvents were examined for their efficacy on pullulan precipitation from fermentation broth. Interactions among four selected solvents and their effect on pullulan yield were studied using response surface methodology. A polynomial model was developed using D-optimal design and three contour plots were generated by performing 20 different experiments and the model was validated by performing optimization experiments. The results indicated that lower concentration of ethanol in combination with the other three solvents has resulted in higher yield of polymer from fermentation broth and the optimized solvent system was able to recover 1.44 times more pullulan as compared to the conventional ethanolic precipitation method. These observations may help in enhancing efficiency of pullulan recovery from fermentation broth and also result in reduced cost of production for the final product.

  18. Solvent-Augmented Mineralization of Pyrene by a Mycobacterium sp.

    Science.gov (United States)

    Jimenez, I Y; Bartha, R

    1996-07-01

    The biodegradation of polycyclic aromatic hydrocarbon pollutants is constrained, in part, by their solid physical state and very low water solubility. Searching for ways to overcome these limitations, we isolated from soil a bacterium capable of growing on pyrene as a sole source of carbon and energy. Acid-fast stain, morphology, and fatty acid profile identified it as a Mycobacterium sp. In a mineral salts solution, the isolate mineralized 50% of a 250-(mu)g/ml concentration of [(sup14)C]pyrene in 2 to 3 days. Detergent below the critical micelle concentration increased the pyrene mineralization rate to 154%, but above the critical micelle concentration, the detergent severely inhibited pyrene mineralization. The water-miscible solvent polyethylene glycol was inhibitory. The hydrophobic solvents heptamethylnonane, decalin, phenyldecane, and diphenylmethane were also inhibitory at several concentrations tested, but the addition of paraffin oil, squalene, squalane, tridecylcyclohexane, and cis-9-tricosene at 0.8% (vol/vol) doubled pyrene mineralization rates by the Mycobacterium sp. without being utilized themselves. The Mycobacterium sp. was found to have high cell surface hydrophobicity and adhered to the emulsified solvent droplets that also contained the dissolved pyrene, facilitating its mass transfer to the degrading bacteria. Cells physically adhering to solvent droplets metabolized pyrene 8.5 times as fast as cells suspended in the aqueous medium. An enhanced mass transfer of polycyclic aromatic hydrocarbon compounds to microorganisms by suitable hydrophobic solvents might allow the development of solvent-augmented biodegradation techniques for use in aqueous or slurry-type bioreactors.

  19. Computer-aided tool for solvent selection in pharmaceutical processes: Solvent swap

    DEFF Research Database (Denmark)

    Papadakis, Emmanouil; K. Tula, Anjan; Gernaey, Krist V.

    In the pharmaceutical processes, solvents have a multipurpose role since different solvents can be used in different stages (such as chemical reactions, separations and purification) in the multistage active pharmaceutical ingredients (APIs) production process. The solvent swap and selection task...

  20. Organic Solvent Effects in Biomass Conversion Reactions.

    Science.gov (United States)

    Shuai, Li; Luterbacher, Jeremy

    2016-01-01

    Transforming lignocellulosic biomass into fuels and chemicals has been intensely studied in recent years. A large amount of work has been dedicated to finding suitable solvent systems, which can improve the transformation of biomass into value-added chemicals. These efforts have been undertaken based on numerous research results that have shown that organic solvents can improve both conversion and selectivity of biomass to platform molecules. We present an overview of these organic solvent effects, which are harnessed in biomass conversion processes, including conversion of biomass to sugars, conversion of sugars to furanic compounds, and production of lignin monomers. A special emphasis is placed on comparing the solvent effects on conversion and product selectivity in water with those in organic solvents while discussing the origins of the differences that arise. We have categorized results as benefiting from two major types of effects: solvent effects on solubility of biomass components including cellulose and lignin and solvent effects on chemical thermodynamics including those affecting reactants, intermediates, products, and/or catalysts. Finally, the challenges of using organic solvents in industrial processes are discussed from the perspective of solvent cost, solvent stability, and solvent safety. We suggest that a holistic view of solvent effects, the mechanistic elucidation of these effects, and the careful consideration of the challenges associated with solvent use could assist researchers in choosing and designing improved solvent systems for targeted biomass conversion processes. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Optimal Bidding and Operation of a Power Plant with Solvent-Based Carbon Capture under a CO2 Allowance Market: A Solution with a Reinforcement Learning-Based Sarsa Temporal-Difference Algorithm

    Directory of Open Access Journals (Sweden)

    Ziang Li

    2017-04-01

    Full Text Available In this paper, a reinforcement learning (RL-based Sarsa temporal-difference (TD algorithm is applied to search for a unified bidding and operation strategy for a coal-fired power plant with monoethanolamine (MEA-based post-combustion carbon capture under different carbon dioxide (CO2 allowance market conditions. The objective of the decision maker for the power plant is to maximize the discounted cumulative profit during the power plant lifetime. Two constraints are considered for the objective formulation. Firstly, the tradeoff between the energy-intensive carbon capture and the electricity generation should be made under presumed fixed fuel consumption. Secondly, the CO2 allowances purchased from the CO2 allowance market should be approximately equal to the quantity of CO2 emission from power generation. Three case studies are demonstrated thereafter. In the first case, we show the convergence of the Sarsa TD algorithm and find a deterministic optimal bidding and operation strategy. In the second case, compared with the independently designed operation and bidding strategies discussed in most of the relevant literature, the Sarsa TD-based unified bidding and operation strategy with time-varying flexible market-oriented CO2 capture levels is demonstrated to help the power plant decision maker gain a higher discounted cumulative profit. In the third case, a competitor operating another power plant identical to the preceding plant is considered under the same CO2 allowance market. The competitor also has carbon capture facilities but applies a different strategy to earn profits. The discounted cumulative profits of the two power plants are then compared, thus exhibiting the competitiveness of the power plant that is using the unified bidding and operation strategy explored by the Sarsa TD algorithm.

  2. Liquid Salt as Green Solvent: A Novel Eco-Friendly Technique to Enhance Solubility and Stability of Poorly Soluble Drugs

    Science.gov (United States)

    Patel, Anant A.

    As a result of tremendous efforts in past few decades, various techniques have been developed in order to resolve solubility issues associated with class II and IV drugs, However, majority of these techniques offer benefits associated with certain drawbacks; majorly including low drug loading, physical instability on storage and excessive use of environmentally challenging organic solvents. Hence, current effort was to develop an eco-friendly technique using liquid salt as green solvent, which can offer improvement in dissolution while maintaining long term stability. The liquid salt formulations (LSF) of poorly soluble model drugs ibuprofen, gemfibrozil and indomethacin were developed using 1-Ethyl-3-methylimidazolium ethyl sulfate (EMIM ES) as a non-toxic and environmentally friendly alternate to organic solvents. Liquid medications containing clear solutions of drug, EMIM ES and polysorbate 20, were adsorbed onto porous carrier Neusilin US2 to form free flowing powder. The LSF demonstrated greater rate and extent of dissolution compared to crystalline drugs. The dissolution data revealed that more than 80% drug release from LSF within 20 mins compared to less than 18% release from pure drugs. As high as 70% w/w liquid loading was achieved while maintaining good flowability and compressibility. In addition, the LSF samples exposed to high temperature and high humidity i.e. 40°C/80% RH for 8 weeks, demonstrated excellent physical stability without any signs of precipitation or crystallization. As most desirable form of administration is tablet, the developed liquid salt formulations were transformed into tablets using design of experiment approach by Design Expert Software. The tablet formulation composition and critical parameter were optimized using Box-Behnken Design. This innovative liquid salt formulation technique offered improvement in dissolution rate and extent as well as contributed to excellent physical stability on storage. Moreover, this formulation

  3. Modeling Carbon Dioxide Capture by Monoethanolamine Solvent with ASPEN Plus

    Science.gov (United States)

    Luo, Tianyi

    Fossil fuels provide approximately 80% of the world's energy demands. Methods for reducing CO2 emissions resulting from fossil fuels include increasing the efficiency of power plants and production processes, decreasing energy demands, in combination with CO2 capture and long term storage (CCS). CO2 capture technologies include post-combustion, pre-combustion, and oxyfuel combustion. The amine-based post-combustion CO2 capture from a coal-fired power plant was studied in this thesis. In case of post-combustion capture, CO2 can be captured by Monoethanolamine solvent (MEA), a primary ethanolamine. MEA can associate with H3O+ to form an ion MEAH+, and can react with CO2 to form a carbonate ion MEACOO-. Commercial code ASPEN Plus was used to simulate the process of CO2 capture and optimize the process parameters and required energy duty. The major part of thermal energy requirement is from the Absorber and Stripper columns. This suggests that process optimization should focus on the Absorption/Desorption process. Optimization results show that the gas-liquid reaction equilibrium is affected by several operating parameters including solvent flow rate, stream temperature, column operating pressure, flue gas composition, solvent concentration and absorber design. With optimized CO2 capture, the energy consumption for solvent regeneration (reboiler thermal duty) was decreased from 5.76 GJ/ton captured CO2 to 4.56 GJ/t CO2. On the other hand, the cost of CO2 capture (and sequestration) could be reduced by limiting size of the Absorber column and operating pressure.

  4. Ultrasound induced green solvent extraction of oil from oleaginous seeds

    OpenAIRE

    Sicaire, Anne-Gaëlle; Abert Vian, Maryline; Fine, Frédéric; Carré, Patrick; Tostain, Sylvain

    2016-01-01

    Ultrasound-assisted extraction of rapeseed oil was investigated and compared with conventional extraction for energy efficiency, throughput time, extraction yield, cleanness, processing cost and product quality. A multivariate study enabled us to define optimal parameters (7.7 W/cm2 for ultrasonic power intensity, 40 °C for processing temperature, and a solid/liquid ratio of 1/15) for ultrasound-assisted extraction of oil from oilseeds to maximize lipid yield while reducing solvent consumptio...

  5. Computer Aided Solvent Selection and Design Framework

    DEFF Research Database (Denmark)

    Mitrofanov, Igor; Conte, Elisa; Abildskov, Jens

    in terms of: physical and chemical properties (solvent-pure properties); Environment, Health and Safety (EHS) characteristic (solvent-EHS properties); operational properties (solvent–solute properties). 3. Performing the search. The search step consists of two stages. The first is a generation and property......, the API molecule can be described in terms of conceptual segments (first step of the method) and, then, the solvent power of the pure solvents can be computed and ranked from the best to the worst (anti-solvent). Hence, the design of a solvent mixture that enhances the API solubility can be performed...... for organic synthesis. This part uses the solvent selection methodology of Gani et al. [4,5], which has been extended to handle multi-step chemical syntheses as well as solvent substitution for specific reaction steps in existing processes. The methodology for organic synthesis accordingly involves five steps...

  6. Sleep disturbances and exposure to organic solvents

    Energy Technology Data Exchange (ETDEWEB)

    Lindelof, B.; Almkvist, O.; Goethe, C. (Huddinge Hospital (Sweden))

    An inquiry about sleep habits and sleep disturbances revealed a significantly higher prevalence of insomnia in a solvent-exposed group than in a comparable group that had no occupational exposure to organic solvents. The solvent-exposed group has also registered an increased consumption of hypnotics, and a significant increase occurred in the number of individuals who had consulted physicians because of sleep disorders. The results indicate that solvent exposure could induce sleep disturbances.

  7. CriticalEd

    DEFF Research Database (Denmark)

    Kjellberg, Caspar Mølholt; Meredith, David

    2014-01-01

    The best text method is commonly applied among music scholars engaged in producing critical editions. In this method, a comment list is compiled, consisting of variant readings and editorial emendations. This list is maintained by inserting the comments into a document as the changes are made...... such as Sibelius or Finale. It was hypothesized that it would be possible to develop a Sibelius plug-in, written in Manuscript 6, that would improve the critical editing work flow, but it was found that the capabilities of this scripting language were insufficient. Instead, a 3-part system was designed and built...

  8. Optimal nutrition during the period of mechanical ventilation decreases mortality in critically ill, long-term female patients: a prospective observational cohort study

    NARCIS (Netherlands)

    Strack van Schijndel, Rob J. M.; Weijs, Peter J. M.; Koopmans, Rixt H.; Sauerwein, Hans P.; Beishuizen, Albertus; Girbes, Armand R. J.

    2009-01-01

    ABSTRACT: INTRODUCTION: Optimal nutrition for intensive care patients has been proposed to be the provision of energy as determined by indirect calorimetry, and protein provision of at least 1.2 grams/kg pre-admission weight per day. The evidence supporting these nutritional goals is based on

  9. Organic solvents in electromembrane extraction: recent insights

    DEFF Research Database (Denmark)

    Huang, Chuixiu; Gjelstad, Astrid; Pedersen-Bjergaard, Stig

    2016-01-01

    articles with focus on EME have been published. The current review summarizes the performance of EME with different organic solvents and discusses several criteria for efficient solvents in EME. In addition, the authors highlight their personal perspective about the most promising organic solvents for EME...

  10. Solvent Extraction of Furfural From Biomass

    Science.gov (United States)

    Humphrey, M. F.

    1984-01-01

    Solvent-extraction method reduces energy required to remove furfural produced during acid hydrolysis of biomass. Acid hydrolysis performed in vessel containing both solvents and reacting ingredients. With intimate contact between solvents and aqueous hydrolyis liqour, furfural removed form liquor almost as fast as it forms.

  11. Optimization and Evaluation Strategy of Esophageal Tissue Preparation Protocols for Metabolomics by LC-MS.

    Science.gov (United States)

    Wang, Huiqing; Xu, Jing; Chen, Yanhua; Zhang, Ruiping; He, Jiuming; Wang, Zhonghua; Zang, Qingce; Wei, Jinfeng; Song, Xiaowei; Abliz, Zeper

    2016-04-05

    Sample preparation is a critical step in tissue metabolomics. Therefore, a comprehensive and systematic strategy for the screening of tissue preparation protocols is highly desirable. In this study, we developed an Optimization and Evaluation Strategy based on LC-MS to screen for a high-extractive efficiency and reproducible esophageal tissue preparation protocol for different types of endogenous metabolites (amino acids, carnitines, cholines, etc.), with a special focus on low-level metabolites. In this strategy, we first selected a large number of target metabolites based on literature survey, previous work in our lab, and known metabolic pathways. For these target metabolites, we tested different solvent extraction methods (biphasic solvent extraction, two-step [TS], stepwise [SW], all-in one [AO]; single-phase solvent extraction, SP) and esophageal tissue disruption methods (homogenized wet tissue [HW], ground wet tissue [GW], and ground dry tissue [GD]). A protocol involving stepwise addition of solvents and a homogenized wet tissue protocol (SWHW) was superior to the others. Finally, we evaluated the stability of endogenous metabolites in esophageal tissues and the sensitivity, reproducibility, and recovery of the optimal protocol. The results proved that the SWHW protocol was robust and adequate for bioanalysis. This strategy will provide important guidance for the standardized and scientific investigation of tissue metabolomics.

  12. Effect of Polymer Concentration, Rotational Speed, and Solvent Mixture on Fiber Formation Using Forcespinning®

    Directory of Open Access Journals (Sweden)

    Nancy Obregon

    2016-06-01

    Full Text Available Polycaprolactone (PCL fibers were produced using Forcespinning® (FS. The effects of PCL concentration, solvent mixture, and the spinneret rotational speed on fiber formation were evaluated. The concentration of the polymer in the solvents was a critical determinant of the solution viscosity. Lower PCL concentrations resulted in low solution viscosities with a correspondingly low fiber production rate with many beads. Bead-free fibers with high production rate and uniform fiber diameter distribution were obtained from the optimum PCL concentration (i.e., 12.5 wt% with tetrahydrofuran (THF as the solvent. The addition of N, N-dimethylformamide (DMF to the THF solvent promoted the gradual formation of beads, split fibers, and generally affected the distribution of fiber diameters. The crystallinity of PCL fibers was also affected by the processing conditions, spinning speed, and solvent mixture.

  13. Solvent cleaning system and method for removing contaminants from solvent used in resin recycling

    Science.gov (United States)

    Bohnert, George W [Harrisonville, MO; Hand, Thomas E [Lee's Summit, MO; DeLaurentiis, Gary M [Jamestown, CA

    2009-01-06

    A two step solvent and carbon dioxide based system that produces essentially contaminant-free synthetic resin material and which further includes a solvent cleaning system for periodically removing the contaminants from the solvent so that the solvent can be reused and the contaminants can be collected and safely discarded in an environmentally safe manner.

  14. Optimization of ultrasonic-assisted extraction procedure of ...

    African Journals Online (AJOL)

    ) of capsaicinoids from hot Chili peppers were determined for large scale preparation. First, single factor experiments were performed to optimize the extraction procedure of capsaicinoids, and initial optimized results were: ratio of solvent to ...

  15. Solvent mediated self-assembly of solids

    Energy Technology Data Exchange (ETDEWEB)

    De Yoreo, J.; Wilson, W.D.; Palmore, T.

    1997-12-12

    Solvent-mediated crystallization represents a robust approach to self-assembly of nanostructures and microstructures. In organic systems, the relative ease with which the structure of hydrogen- bonded molecules can be manipulated allows for generation of a wide variety of nanoscale crystal structures. In living organisms, control over the micron-to-millimeter form of inorganic crystals is achieved through introduction of bio-organic molecules. The purpose of this proposal is to understand the interplay between solution chemistry, molecular structure, surface chemistry, and the processes of nucleation and crystal growth in solvent-mediated systems, with the goal of developing the atomic and molecular basis of a solvent-mediated self-assembly technology. We will achieve this purpose by: (1) utilizing an atomic force microscopy (AFM) approach that provides in situ, real time imaging during growth from solutions, (2) by modifying kinetic Monte Carlo (KMC) models to include solution-surface kinetics, (3) by introducing quantum chemistry (QC) calculations of the potentials of the relevant chemical species and the near-surface structure of the solution, and (4) by utilizing molecular dynamics (MD) simulations to identify the minimum energy pathways to the solid state. Our work will focus on two systems chosen to address both the manometer and micron-to-millimeter length scales of assembly, the family of 2,5- diketopiperazines (X-DKPs) and the system of CaCO{sub 3} with amino acids. Using AFM, we will record the evolution of surface morphology, critical lengths, step speeds, and step-step interactions as a function of supersaturation and temperature. In the case of the X-DKPs, these measurements will be repeated as the molecular structure of the growth unit is varied. In the case of CaCO{sub 3}, they will be performed as a function of solution chemistry including pH, ionic strength, and amino acid content. In addition, we will measure nucleation rates and orientations of

  16. Effect of operating parameters on mechanical expression of solvent-soaked soybean-grits.

    Science.gov (United States)

    Sinha, Lalan Kumar; Haldar, Swarrna; Majumdar, Gautam Chandra

    2015-05-01

    Oil from soybean is obtained mostly by solvent extraction of soybean flakes. Legislation banning the use of hexane as solvent for extracting edible vegetable oil has forced a search for an alternative solvent and for developing a suitable oil recovery process. Expellers are being used for obtaining vegetable oil by mechanical means (expression) from oil seeds having oil content higher than 20 %. It was felt, in view of the stiffness of the soybean matrix, a combination of solvent treatment and expression could be a cheaper alternative; thus an attempt has been made here to develop a two stage process constituting soaking of soybean grits in solvent followed by mechanical compression (hydraulic press) of solvent-soaked grits to recover oil. The present work aimed at studying the effect of various process parameters on oil yield from solvent soaked soybean-grits during soaking as well as pressing stages using the solvents: hexane, ethanol (alternative solvent). The process parameters were identified through holistic approach. The dependant variable was oil recovery (expressed as fraction of initial oil content of soybean) whereas the independent parameters were particle size, solvent-bean mass ratio, soaking time, soaking temperature, applied pressure and pressing time. The effect of each of the above parameters on fractional oil recovery (FOR) was studied. The results of the present study indicate that the above parameters have a significant effect on the fractional oil recovery with particle size, soaking temperature, soaking time and pressing time being the most significant factors. The present study also indicates that ethanol can be used as an alternate solvent to hexane by optimizing the factors as discussed in this paper.

  17. Critical parameters in the MCF-7 cell proliferation bioassay (E-Screen)

    DEFF Research Database (Denmark)

    Rasmussen, Thomas Høj; Nielsen, Jesper Bo

    2002-01-01

    of hormone-free controls. In the highly responsive MCF-7 BUS cell line, we evaluated critical assay parameters for test performance, including growth conditions, initial seeding densities and differences in growth stimulation in medium containing human serum or fetal calf serum as well as appropriate...... solvents for oestrogen-mimicking compounds. Modifications significantly reduced the labour-intensive steps and overall assay costs without affecting the sensitivity of the assay. Using this optimized test regimen, the responsiveness of treated MCF-7 BUS cells was consistently increased up to 11-fold over...

  18. Parental occupational exposure to organic solvents and anencephaly in Mexico.

    Science.gov (United States)

    Aguilar-Garduño, C; Lacasaña, M; Blanco-Muñoz, J; Borja-Aburto, V Hugo; García, A M

    2010-01-01

    To assess the relationship between parental occupational exposure to organic solvents, and the risk of anencephaly in Mexico. A case-control study was conducted based on the registers of the Epidemiological Surveillance System for Neural Tube Defects in Mexico; 151 cases of anencephaly of > or =20 weeks' gestation were included. A control, born alive and without any apparent congenital malformations at birth, was selected for each case in the same maternity service in which the case was born. Information on occupational exposures, lifestyle habits, reproductive history, use of medicines, supplementation with multivitamins and folic acid, was obtained by a general questionnaire; a food frequency questionnaire was also applied to obtain information of daily intake of folate and other B vitamins. Occupational exposure to organic solvents was based on job title as a proxy for exposure and analysed considering two critical periods around conception. In logistic regression analysis, the odds of having a child with anencephaly was higher if the mother or the father was occupationally exposed to organic solvents during the periconceptional period, or when both parents or at least one of them were occupationally exposed during this period with an adjusted odds ratio of 2.97 (95% CI 1.36 to 6.52). The results support the hypothesis that both maternal and paternal occupational exposure to organic solvents can increase the probability of having a child with anencephaly.

  19. Solvent-Induced Reversal of Activities between Two Closely Related Heterogeneous Catalysts in the Aldol Reaction

    Energy Technology Data Exchange (ETDEWEB)

    Kandel, Kapil [Ames Laboratory; Althaus, Stacey M [Ames Laboratory; Peeraphatdit, Chorthip [Ames Laboratory; Kobayashi, Takeshi [Ames Laboratory; Trewyn, Brian G [Ames Laboratory; Pruski, Marek [Ames Laboratory; Slowing, Igor I [Ames Laboratory

    2013-01-11

    The relative rates of the aldol reaction catalyzed by supported primary and secondary amines can be inverted by 2 orders of magnitude, depending on the use of hexane or water as a solvent. Our analyses suggest that this dramatic shift in the catalytic behavior of the supported amines does not involve differences in reaction mechanism, but is caused by activation of imine to enamine equilibria and stabilization of iminium species. The effects of solvent polarity and acidity were found to be important to the performance of the catalytic reaction. This study highlights the critical role of solvent in multicomponent heterogeneous catalytic processes.

  20. Carbon dioxide insertion into diamines: a computational study of solvent effects.

    Science.gov (United States)

    Eger, Wilhelm A; Genest, Alexander; Rieger, Bernhard; Rösch, Notker

    2012-10-01

    We studied computationally, on the model compound ethylenediamine, the insertion of carbon dioxide into diamines, yielding cyclic urea compounds. Two mechanisms were elaborated, depending on the value of the dielectric constant (DC) of the solvent. Accordingly, reaction mixtures with a high DC lead to carbamates, whereas lower DC values result in the preferred product cyclic urea. Additives behaving as "proton shuttles" act as catalysts, significantly reducing the activation barriers of insertion and ring closure to surmountable values. CO(2) insertion into diamines may also occur by autocatalysis, even without further additives, but under less favorable conditions, for example, lower yields. Amine reagents are most efficient at proton shuttling, followed by alcohols. The activation barrier of the rate-limiting step is lowered in a reaction mixture with higher values of DC, up to a critical value ε(cr) ≈ 18. Hence, in a suitably optimized reaction mixture, ring closure is suggested to occur under milder conditions than those previously applied experimentally. The two roles of the additive, that is, acting as proton shuttling agent and adjusting the effective DC of the reaction mixture, do not have to be assigned to a single compound, possibly affording a handle on process optimization. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Nutrition in critical illness.

    Science.gov (United States)

    Chan, Daniel L; Freeman, Lisa M

    2006-11-01

    Malnutrition associated with critical illness has been unequivocally associated with increased morbidity and mortality in humans. Because malnutrition may similarly affect veterinary patients, the nutritional requirements of hospitalized critically ill animals must be properly addressed. Proper nutritional support is increasingly being recognized as an important therapeutic intervention in the care of critically ill patients. The current focus of veterinary critical care nutrition, and the major focus of this article, is on carefully selecting the patients most likely to benefit from nutritional support, deciding when to intervene, and optimizing nutritional support to individual patients.

  2. Influence of solvent polarity and supersaturation on template-induced nucleation of carbamazepine crystal polymorphs

    Science.gov (United States)

    Parambil, Jose V.; Poornachary, Sendhil K.; Tan, Reginald B. H.; Heng, Jerry Y. Y.

    2017-07-01

    Studies on the use of template surfaces to induce heterogeneous crystal nucleation have gained momentum in recent years-with potential applications in selective crystallisation of polymorphs and in the generation of seed crystals in a continuous crystallisation process. In developing a template-assisted solution crystallisation process, the kinetics of homogeneous versus heterogeneous crystal nucleation could be influenced by solute-solvent, solute-template, and solvent-template interactions. In this study, we report the effect of solvents of varying polarity on the nucleation of carbamazepine (CBZ) crystal polymorphs, a model active pharmaceutical ingredient. The experimental results demonstrate that functionalised template surfaces are effective in promoting crystallisation of either the metastable (form II) or stable (form III) polymorphs of CBZ only in moderately (methanol, ethanol, isopropanol) and low polar (toluene) solvents. A solvent with high polarity (acetonitrile) is thought to mask the template effect on heterogeneous nucleation due to strong solute-solvent and solvent-template interactions. The current study highlights that a quality-by-design (QbD) approach-considering the synergistic effects of solute concentration, solvent type, solution temperature, and template surface chemistry on crystal nucleation-is critical to the development of a template-induced crystallisation process.

  3. Optimization of Temperature Distributions in Critical Cross-sections of Load-bearing Structures of Measurement Optical Systems of Autonomous Objects

    Directory of Open Access Journals (Sweden)

    Livshits Michael Yu.

    2017-01-01

    Full Text Available Problem of the automatic thermogradient stabilization of the constructive elements sizes is discussed. The actual problem is the determination of the control algorithm controlled heat sources, providing them with the minimum possible number of minimal deviation from the desired temperature in a given cross-section design. The proposed procedure for solving optimal control of temperature distribution in the numerical design of its implementation, allows obtaining results that are suitable for approximate implementation in on-Board computers, Autonomous systems and significantly reduce thermal deformation component of the measurement error.

  4. Advanced integrated solvent extraction systems

    Energy Technology Data Exchange (ETDEWEB)

    Horwitz, E.P.; Dietz, M.L.; Leonard, R.A. [Argonne National Lab., IL (United States)

    1997-10-01

    Advanced integrated solvent extraction systems are a series of novel solvent extraction (SX) processes that will remove and recover all of the major radioisotopes from acidic-dissolved sludge or other acidic high-level wastes. The major focus of this effort during the last 2 years has been the development of a combined cesium-strontium extraction/recovery process, the Combined CSEX-SREX Process. The Combined CSEX-SREX Process relies on a mixture of a strontium-selective macrocyclic polyether and a novel cesium-selective extractant based on dibenzo 18-crown-6. The process offers several potential advantages over possible alternatives in a chemical processing scheme for high-level waste treatment. First, if the process is applied as the first step in chemical pretreatment, the radiation level for all subsequent processing steps (e.g., transuranic extraction/recovery, or TRUEX) will be significantly reduced. Thus, less costly shielding would be required. The second advantage of the Combined CSEX-SREX Process is that the recovered Cs-Sr fraction is non-transuranic, and therefore will decay to low-level waste after only a few hundred years. Finally, combining individual processes into a single process will reduce the amount of equipment required to pretreat the waste and therefore reduce the size and cost of the waste processing facility. In an ongoing collaboration with Lockheed Martin Idaho Technology Company (LMITCO), the authors have successfully tested various segments of the Advanced Integrated Solvent Extraction Systems. Eichrom Industries, Inc. (Darien, IL) synthesizes and markets the Sr extractant and can supply the Cs extractant on a limited basis. Plans are under way to perform a test of the Combined CSEX-SREX Process with real waste at LMITCO in the near future.

  5. Deacidification of Soybean Oil Combining Solvent Extraction and Membrane Technology

    Directory of Open Access Journals (Sweden)

    M. L. Fornasero

    2013-01-01

    Full Text Available The aim of this work was to study the removal of free fatty acids (FFAs from soybean oil, combining solvent extraction (liquid-liquid for the separation of FFAs from the oil and membrane technology to recover the solvent through nanofiltration (NF. Degummed soybean oil containing 1.05 ± 0.10% w/w FFAs was deacidified by extraction with ethanol. Results obtained in the experiences of FFAs extraction from oil show that the optimal operating conditions are the following: 1.8 : 1 w : w ethanol/oil ratio, 30 minutes extraction time and high speed of agitation and 30 minutes repose time after extraction at ambient temperature. As a result of these operations two phases are obtained: deacidified oil phase and ethanol phase (containing the FFAs. The oil from the first extraction is subjected to a second extraction under the same conditions, reducing the FFA concentration in oil to 0.09%. Solvent recovery from the ethanol phase is performed using nanofiltration technology with a commercially available polymeric NF membrane (NF-99-HF, Alfa Laval. From the analysis of the results we can conclude that the optimal operating conditions are pressure of 20 bar and temperature of 35°C, allowing better separation performance: permeate flux of 28.3 L/m2·h and FFA retention of 70%.

  6. Comparisons of amine solvents for post-combustion CO{sub 2} capture: A multi-objective analysis approach

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Anita S; Eslick, John C; Miller, David C; Kitchin, John R

    2013-10-01

    Amine solvents are of great interest for post-combustion CO{sub 2} capture applications. Although the development of new solvents is predominantly conducted at the laboratory scale, the ability to assess the performance of newly developed solvents at the process scale is crucial to identifying the best solvents for CO{sub 2} capture. In this work we present a methodology to evaluate and objectively compare the process performance of different solvents. We use Aspen Plus, with the electrolyte-NRTL thermodynamic model for the solvent CO{sub 2} interactions, coupled with a multi-objective genetic algorithm optimization to determine the best process design and operating conditions for each solvent. This ensures that the processes utilized for the comparison are those which are best suited for the specific solvent. We evaluate and compare the process performance of monoethanolamine (MEA), diethanolamine (DEA), and 2-amino-2-methyl-1-propanol (AMP) in a 90% CO{sub 2} capture process from a 550 MW coal fired power plant. From our analysis the best process specifications are amine specific and with those specific, optimized specifications DEA has the potential to be a better performing solvent than MEA, with a lower energy penalty and lower capital cost investment.

  7. Quality by design case study 1: Design of 5-fluorouracil loaded lipid nanoparticles by the W/O/W double emulsion - Solvent evaporation method.

    Science.gov (United States)

    Amasya, Gulin; Badilli, Ulya; Aksu, Buket; Tarimci, Nilufer

    2016-03-10

    With Quality by Design (QbD), a systematic approach involving design and development of all production processes to achieve the final product with a predetermined quality, you work within a design space that determines the critical formulation and process parameters. Verification of the quality of the final product is no longer necessary. In the current study, the QbD approach was used in the preparation of lipid nanoparticle formulations to improve skin penetration of 5-Fluorouracil, a widely-used compound for treating non-melanoma skin cancer. 5-Fluorouracil-loaded lipid nanoparticles were prepared by the W/O/W double emulsion - solvent evaporation method. Artificial neural network software was used to evaluate the data obtained from the lipid nanoparticle formulations, to establish the design space, and to optimize the formulations. Two different artificial neural network models were developed. The limit values of the design space of the inputs and outputs obtained by both models were found to be within the knowledge space. The optimal formulations recommended by the models were prepared and the critical quality attributes belonging to those formulations were assigned. The experimental results remained within the design space limit values. Consequently, optimal formulations with the critical quality attributes determined to achieve the Quality Target Product Profile were successfully obtained within the design space by following the QbD steps. Copyright © 2016 Elsevier B.V. All rights reserved.

  8. Development of Solvent Extraction Approach to Recycle Enriched Molybdenum Material

    Energy Technology Data Exchange (ETDEWEB)

    Tkac, Peter [Argonne National Lab. (ANL), Argonne, IL (United States). Nuclear Engineering Division; Brown, M. Alex [Argonne National Lab. (ANL), Argonne, IL (United States). Nuclear Engineering Division; Sen, Sujat [Argonne National Lab. (ANL), Argonne, IL (United States). Energy Systems Division; Bowers, Delbert L. [Argonne National Lab. (ANL), Argonne, IL (United States). Nuclear Engineering Division; Wardle, Kent [Argonne National Lab. (ANL), Argonne, IL (United States). Nuclear Engineering Division; Copple, Jacqueline M. [Argonne National Lab. (ANL), Argonne, IL (United States). Nuclear Engineering Division; Pupek, Krzysztof Z. [Argonne National Lab. (ANL), Argonne, IL (United States). Nuclear Engineering Division; Dzwiniel, Trevor L. [Argonne National Lab. (ANL), Argonne, IL (United States). Energy Systems Division; Pereira, Candido [Argonne National Lab. (ANL), Argonne, IL (United States). Nuclear Engineering Division; Krumdick, Gregory K. [Argonne National Lab. (ANL), Argonne, IL (United States). Energy Systems Division; Vandegrift, George F. [Argonne National Lab. (ANL), Argonne, IL (United States). Nuclear Engineering Division

    2016-06-01

    Argonne National Laboratory, in cooperation with Oak Ridge National Laboratory and NorthStar Medical Technologies, LLC, is developing a recycling process for a solution containing valuable Mo-100 or Mo-98 enriched material. Previously, Argonne had developed a recycle process using a precipitation technique. However, this process is labor intensive and can lead to production of large volumes of highly corrosive waste. This report discusses an alternative process to recover enriched Mo in the form of ammonium heptamolybdate by using solvent extraction. Small-scale experiments determined the optimal conditions for effective extraction of high Mo concentrations. Methods were developed for removal of ammonium chloride from the molybdenum product of the solvent extraction process. In large-scale experiments, very good purification from potassium and other elements was observed with very high recovery yields (~98%).

  9. Optimization of radiotherapy to target volumes with concave outlines: target-dose homogenization and selective sparing of critical structures by constrained matrix inversion

    Energy Technology Data Exchange (ETDEWEB)

    Colle, C.; Van den Berge, D.; De Wagter, C.; Fortan, L.; Van Duyse, B.; De Neve, W.

    1995-12-01

    The design of 3D-conformal dose distributions for targets with concave outlines is a technical challenge in conformal radiotherapy. For these targets, it is impossible to find beam incidences for which the target volume can be isolated from the tissues at risk. Commonly occurring examples are most thyroid cancers and the targets located at the lower neck and upper mediastinal levels related to some head and neck. A solution to this problem was developed, using beam intensity modulation executed with a multileaf collimator by applying a static beam-segmentation technique. The method includes the definition of beam incidences and beam segments of specific shape as well as the calculation of segment weights. Tests on Sherouse`s GRATISTM planning system allowed to escalate the dose to these targets to 65-70 Gy without exceeding spinal cord tolerance. Further optimization by constrained matrix inversion was investigated to explore the possibility of further dose escalation.

  10. Modular Polymer Biosensors by Solvent Immersion Imprint Lithography

    Energy Technology Data Exchange (ETDEWEB)

    Moore, Jayven S.; Xantheas, Sotiris S.; Grate, Jay W.; Wietsma, Thomas W.; Gratton, Enrico; Vasdekis, Andreas

    2016-01-01

    We recently demonstrated Solvent Immersion Imprint Lithography (SIIL), a rapid benchtop microsystem prototyping technique, including polymer functionalization, imprinting and bonding. Here, we focus on the realization of planar polymer sensors using SIIL through simple solvent immersion without imprinting. We describe SIIL’s impregnation characteristics, including an inherent mechanism that not only achieves practical doping concentrations, but their unexpected 4-fold enhancement compared to the immersion solution. Subsequently, we developed and characterized optical sensors for detecting molecular O2. To this end, a high dynamic range is reported, including its control through the immersion duration, a manifestation of SIIL’s modularity. Overall, SIIL exhibits the potential of improving the operating characteristics of polymer sensors, while significantly accelerating their prototyping, as it requires a few seconds of processing and no need for substrates or dedicated instrumentation. These are critical for O2 sensing as probed by way of example here, as well as any polymer permeable reactant.

  11. Solvent characterization using the dispersion number

    Energy Technology Data Exchange (ETDEWEB)

    Leonard, R. A.

    1993-10-06

    When developing new solvent extraction processes, one often has to evaluate new solvents, new aqueous phases, or both for their ability to work in plant-scale equipment. To facilitate solvent characterization, a simple test is proposed based on the dimensionless dispersion number (N{sub Di}). It allows one to characterize the ability of the solvent to separate from a two-phase dispersion and allows one to estimate process throughput for equipment of a given size. Several ways to carry out the N{sub Di} test are given, including a standard test procedure. The N{sub Di} test was applied to the performance of solvent extraction equipment with discrete process stages, the leaching of plasticizers from plastic tubing, and the development of a new solvent for the combined extraction of strontium and transuranic elements.

  12. Toxic hepatitis in occupational exposure to solvents

    OpenAIRE

    Malaguarnera, Giulia; Cataudella, Emanuela; Giordano, Maria; Nunnari, Giuseppe; Chisari, Giuseppe; Malaguarnera, Mariano

    2012-01-01

    The liver is the main organ responsible for the metabolism of drugs and toxic chemicals, and so is the primary target organ for many organic solvents. Work activities with hepatotoxins exposures are numerous and, moreover, organic solvents are used in various industrial processes. Organic solvents used in different industrial processes may be associated with hepatotoxicity. Several factors contribute to liver toxicity; among these are: species differences, nutritional condition, genetic facto...

  13. Organic Solvent Effects in Biomass Conversion Reactions

    OpenAIRE

    Shuai, Li; LUTERBACHER, Jeremy

    2016-01-01

    Transforming lignocellulosic biomass into fuels and chemicals has been intensely studied in recent years. A large amount of work has been dedicated to finding suitable solvent systems, which can improve the transformation of biomass into value-added chemicals. These efforts have been undertaken based on numerous research results that have shown that organic solvents can improve both conversion and selectivity of biomass to platform molecules. We present an overview of these organic solvent ef...

  14. Femtosecond dynamics in hydrogen-bonded solvents

    Energy Technology Data Exchange (ETDEWEB)

    Castner, E.W. Jr.; Chang, Y.J.

    1993-09-01

    We present results on the ultrafast dynamics of pure hydrogen-bonding solvents, obtained using femtosecond Fourier-transform optical-heterodyne-detected, Raman-induced Kerr effect spectroscopy. Solvent systems we have studied include the formamides, water, ethylene glycol, and acetic acid. Inertial and diffusive motions are clearly resolved. We comment on the effect that such ultrafast solvent motions have on chemical reactions in solution.

  15. Supercritical solvent extraction of oil sand bitumen

    Science.gov (United States)

    Imanbayev, Ye. I.; Ongarbayev, Ye. K.; Tileuberdi, Ye.; Mansurov, Z. A.; Golovko, A. K.; Rudyk, S.

    2017-08-01

    The supercritical solvent extraction of bitumen from oil sand studied with organic solvents. The experiments were performed in autoclave reactor at temperature above 255 °C and pressure 29 atm with stirring for 6 h. The reaction resulted in the formation of coke products with mineral part of oil sands. The remaining products separated into SARA fractions. The properties of the obtained products were studied. The supercritical solvent extraction significantly upgraded extracted natural bitumen.

  16. Aminosilicone solvent recovery methods and systems

    Energy Technology Data Exchange (ETDEWEB)

    Spiry, Irina Pavlovna; Perry, Robert James; Wood, Benjamin Rue; Singh, Surinder Prabhjot; Farnum, Rachel Lizabeth; Genovese, Sarah Elizabeth

    2018-02-13

    The present invention is directed to aminosilicone solvent recovery methods and systems. The methods and systems disclosed herein may be used to recover aminosilicone solvent from a carbon dioxide containing vapor stream, for example, a vapor stream that leaves an aminosilicone solvent desorber apparatus. The methods and systems of the invention utilize a first condensation process at a temperature from about 80.degree. C. to about 150.degree. C. and a second condensation process at a temperature from about 5.degree. C. to about 75.degree. C. The first condensation process yields recovered aminosilicone solvent. The second condensation process yields water.

  17. Screening method for solvent selection used in tar removal by the absorption process.

    Science.gov (United States)

    Masurel, Eve; Authier, Olivier; Castel, Christophe; Roizard, Christine

    2015-01-01

    The aim of this paper is the study of the treatment of flue gas issued from a process of biomass gasification in fluidized bed. The flue gas contains tar which should be selectively removed from the fuel components of interest (e.g. H2, CO and light hydrocarbons) to avoid condensation and deposits in internal combustion engine. The chosen flue gas treatment is the gas-liquid absorption using solvents, which present specific physicochemical properties (e.g. solubility, viscosity, volatility and chemical and thermal stability) in order to optimize the unit on energetic, technico-economic and environmental criteria. The rational choice of the proper solvent is essential for solving the tar issue. The preselection of the solvents is made using a Hansen parameter in order to evaluate the tar solubility and the saturation vapour pressure of the solvent is obtained using Antoine law. Among the nine families of screened solvents (alcohols, amines, ketones, halogenates, ethers, esters, hydrocarbons, sulphured and chlorinates), acids methyl esters arise as solvents of interest. Methyl oleate has then been selected and studied furthermore. Experimental liquid-vapour equilibrium data using bubbling point and absorption cell measurements and theoretical results obtained by the UNIFAC-Dortmund model confirm the high potential of this solvent and the good agreement between experimental and theoretical results.

  18. How to improve a critical performance for an ExoMars 2020 Scientific Instrument (RLS). Raman Laser Spectrometer Signal to Noise Ratio (SNR) Optimization

    Science.gov (United States)

    Canora, C. P.; Moral, A. G.; Rull, F.; Maurice, S.; Hutchinson, I.; Ramos, G.; López-Reyes, G.; Belenguer, T.; Canchal, R.; Prieto, J. A. R.; Rodriguez, P.; Santamaria, P.; Berrocal, A.; Colombo, M.; Gallago, P.; Seoane, L.; Quintana, C.; Ibarmia, S.; Zafra, J.; Saiz, J.; Santiago, A.; Marin, A.; Gordillo, C.; Escribano, D.; Sanz-Palominoa, M.

    2017-09-01

    The Raman Laser Spectrometer (RLS) is one of the Pasteur Payload instruments, within the ESA's Aurora Exploration Programme, ExoMars mission. Raman spectroscopy is based on the analysis of spectral fingerprints due to the inelastic scattering of light when interacting with matter. RLS is composed by Units: SPU (Spectrometer Unit), iOH (Internal Optical Head), and ICEU (Instrument Control and Excitation Unit) and the harnesses (EH and OH). The iOH focuses the excitation laser on the samples and collects the Raman emission from the sample via SPU (CCD) and the video data (analog) is received, digitalizing it and transmiting it to the processor module (ICEU). The main sources of noise arise from the sample, the background, and the instrument (Laser, CCD, focuss, acquisition parameters, operation control). In this last case the sources are mainly perturbations from the optics, dark signal and readout noise. Also flicker noise arising from laser emission fluctuations can be considered as instrument noise. In order to evaluate the SNR of a Raman instrument in a practical manner it is useful to perform end-to-end measurements on given standards samples. These measurements have to be compared with radiometric simulations using Raman efficiency values from literature and taking into account the different instrumental contributions to the SNR. The RLS EQM instrument performances results and its functionalities have been demonstrated in accordance with the science expectations. The Instrument obtained SNR performances in the RLS EQM will be compared experimentally and via analysis, with the Instrument Radiometric Model tool. The characterization process for SNR optimization is still on going. The operational parameters and RLS algorithms (fluorescence removal and acquisition parameters estimation) will be improved in future models (EQM-2) until FM Model delivery.

  19. Population Pharmacokinetics and Pharmacodynamics Modeling To Optimize Dosage Regimens of Sulbactam in Critically Ill Patients with Severe Sepsis Caused by Acinetobacter baumannii.

    Science.gov (United States)

    Jaruratanasirikul, Sutep; Wongpoowarak, Wibul; Wattanavijitkul, Thitima; Sukarnjanaset, Waroonrat; Samaeng, Maseetoh; Nawakitrangsan, Monchana; Ingviya, Natnicha

    2016-12-01

    Sulbactam is being considered as an alternative concomitant medication with other effective antibiotics for the treatment of multidrug-resistant (MDR) Acinetobacter baumannii infections. Pathophysiological changes in critically ill patients with severe sepsis, resulting in altered pharmacokinetic (PK) patterns for antibiotics, are important factors in determining therapeutic success. The aims of this study were (i) to examine the population PK parameters and (ii) to assess the probability of target attainment (PTA) for sulbactam in patients with severe sepsis caused by A. baumannii PK studies were carried out following administration of 2 g of sulbactam every 12 h on the 4th day of drug administration in 27 patients, and a Monte Carlo simulation was performed to determine the PTA of achieving 40% exposure time during which the plasma drug concentration remained above the MIC (T>MIC) and 60% T>MIC The central and peripheral volumes of distribution were 14.56 and 9.55 liters, respectively, and total clearances of sulbactam were 2.26 liters/h and 7.64 liters/h in patients aged >65 years and ≤65 years, respectively. The high PTAs (≥90%) for targets of 40% T>MIC and 60% T>MIC with a MIC of 4 μg/ml were observed when sulbactam was administered by a 4-h infusion of 1 g every 12 h and 1 g every 8 h, respectively. Sulbactam would be an alternative antibiotic option to coadminister with colistin for the treatment of infections caused by MDR A. baumannii However, for pathogens with MICs of >4 μg/ml, higher dosage regimens of sulbactam are required. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

  20. Application of solvent microextraction to the analysis of nitroaromatic explosives in water samples.

    Science.gov (United States)

    Psillakis, E; Kalogerakis, N

    2001-01-12

    The application of solvent microextraction to the analysis of nitroaromatic explosives is presented. Extraction of 11 nitroaromatics was achieved by suspending 1 microl of organic solvent to the tip of a microsyringe in a stirred aqueous solution. Parameters such as extraction solvent, stirring rate, salt concentration and sampling time were studied and optimized. The limits of detection using bench-top quadrupole mass spectrometry and short extraction times (15 min) were found to be between 0.08 and 1.3 microg/l and the relative standard deviations ranged between 4.3 and 9.8%. Although precision and accuracy of quantification of the method are still needed, solvent microextraction proved to be a fast, simple and inexpensive tool for preconcentration and matrix isolation of nitroaromatics on a microscale.

  1. Processing Solvent-Dependent Electronic and Structural Properties of Cesium Lead Triiodide Thin Films.

    Science.gov (United States)

    Ramadan, Alexandra J; Rochford, Luke A; Fearn, Sarah; Snaith, Henry J

    2017-09-07

    Cesium lead triiodide (CsPbI3) is an attractive material for photovoltaic applications due to its appropriate band gap, strong optical absorption, and high thermal stability. However, the perovskite phase suffers from moisture induced structural instability. Previous studies have utilized a range of solvent systems to establish the role of solvent choice in structural instabilities. Despite this, effects of different solvents on the electronic structure of this material have not been compared. We report substantial chemical and compositional differences in thin films of CsPbI3 prepared from a range of solvent systems. We confirm via X-ray diffraction thin films formed from DMF, DMSO, and a mixture of these solvent systems share the same crystal structure. However, secondary ion mass spectrometry, X-ray photoelectron spectroscopy, and low energy ion scattering measurements reveal significant differences between films processed via different solvent systems. Our findings reveal the critical impact solvents have upon compositional stoichiometry and thin-film morphology.

  2. A Nonlocal Poisson-Fermi Model for Ionic Solvent

    CERN Document Server

    Xie, Dexuan; Eisenberg, Bob; Scott, L Ridgway

    2016-01-01

    We propose a nonlocal Poisson-Fermi model for ionic solvent that includes ion size effects and polarization correlations among water molecules in the calculation of electrostatic potential. It includes the previous Poisson-Fermi models as special cases, and its solution is the convolution of a solution of the corresponding nonlocal Poisson dielectric model with a Yukawa-type kernel function. Moreover, the Fermi distribution is shown to be a set of optimal ionic concentration functions in the sense of minimizing an electrostatic potential free energy. Finally, numerical results are reported to show the difference between a Poisson-Fermi solution and a corresponding Poisson solution.

  3. Thinking Critically about Critical Thinking

    Science.gov (United States)

    Mulnix, Jennifer Wilson

    2012-01-01

    As a philosophy professor, one of my central goals is to teach students to think critically. However, one difficulty with determining whether critical thinking can be taught, or even measured, is that there is widespread disagreement over what critical thinking actually is. Here, I reflect on several conceptions of critical thinking, subjecting…

  4. Remediation of Contaminated Soils by Solvent Flushing

    NARCIS (Netherlands)

    Augustijn, Dionysius C.M.; Jessup, Ron E.; Rao, P. Suresh C.; Wood, A. Lynn

    1994-01-01

    Solvent flushing is a potential technique for remediating a waste disposal/spill site contaminated with organic chemicals. This technique involves the injection of a solvent mixture (e.g., water plus alcohols) that enhances contaminant solubility, reduces the retardation factor, and increases the

  5. SOLVENT EFFECTS IN THE HYDROXIDE AND ALKOXIDE ...

    African Journals Online (AJOL)

    in the rationalization or correlation of solvent effects on reaction rates and activation parameters. The objective of the present investigation was to examine the effect of these solvent parameters on the rates of the alkaline decomposition ... metal (,BDH} and methanol, the concentrations were determined by titration.

  6. Molecular Thermodynamic Modeling of Mixed Solvent Solubility

    DEFF Research Database (Denmark)

    Ellegaard, Martin Dela; Abildskov, Jens; O’Connell, John P.

    2010-01-01

    A method based on statistical mechanical fluctuation solution theory for composition derivatives of activity coefficients is employed for estimating dilute solubilities of 11 solid pharmaceutical solutes in nearly 70 mixed aqueous and nonaqueous solvent systems. The solvent mixtures range from ne...

  7. A spreadsheet algorithm for stagewise solvent extraction

    Energy Technology Data Exchange (ETDEWEB)

    Leonard, R.A.; Regalbuto, M.C.

    1993-01-01

    Part of the novelty is the way in which the problem is organized in the spreadsheet. In addition, to facilitate spreadsheet setup, a new calculational procedure has been developed. The resulting Spreadsheet Algorithm for Stagewise Solvent Extraction (SASSE) can be used with either IBM or Macintosh personal computers as a simple yet powerful tool for analyzing solvent extraction flowsheets.

  8. Microfluidic Free-Flow Electrophoresis Based Solvent Exchanger for Continuously Operating Lab-on-Chip Applications.

    Science.gov (United States)

    Zitzmann, Franziska D; Jahnke, Heinz-Georg; Pfeiffer, Simon A; Frank, Ronny; Nitschke, Felix; Mauritz, Laura; Abel, Bernd; Belder, Detlev; Robitzki, Andrea A

    2017-12-19

    For miniaturization and integration of chemical synthesis and analytics on small length scales, the development of complex lab-on-chip (LOC) systems is in the focus of many current research projects. While application specific synthesis and analytic modules and LOC devices are widely described, the combination and integration of different modules is intensively investigated. Problems for in-line processes such as solvent incompatibilities, e.g., for a multistep synthesis or the combination of an organic drug synthesis with a cell-based biological activity testing system, require a solvent exchange between serialized modules. Here, we present a continuously operating microfluidic solvent exchanger based on the principle of free-flow electrophoresis for miscible organic/aqueous fluids. We highlight a proof-of-principle and describe the working principle for the model compound fluorescein, where the organic solvent DMSO is exchanged against an aqueous buffer. The DMSO removal performance could be significantly increased to 95% by optimization of the microfluidic layout. Moreover, the optimization of the inlet flow ratio resulted in a minimized dilution factor of 5, and we were able to demonstrate that a reduction of the supporting instrumentation is possible without a significant decrease of the DMSO removal performance. Finally, the compatibility of the developed solvent exchanger for cell based downstream applications was proven. The impedimetric monitoring of HEK293A cells in a continuously operating microfluidic setup revealed no adverse effects of the residual DMSO after the solvent replacement. Our solvent exchanger device demonstrates the power of micro-free-flow electrophoresis not only as a powerful technique for separation and purification of compound mixtures but also for solvent replacement.

  9. Gradient Solvent Vapor Annealing of Thin Films

    Science.gov (United States)

    Albert, Julie; Bogart, Timothy; Lewis, Ronald; Epps, Thomas

    2011-03-01

    The development of block copolymer materials for emerging nanotechnologies requires an understanding of how surface energy/chemistry and annealing conditions affect thin film self-assembly. Specifically, in solvent vapor annealing (SVA), the use of solvent mixtures and the manipulation of solvent vapor concentration are promising approaches for obtaining a desired morphology or nanostructure orientation. We designed and fabricated solvent-resistant devices to produce discrete SVA gradients in composition and/or concentration to efficiently explore SVA parameter space. We annealed copolymer films containing poly(styrene), poly(isoprene), and/or poly(methyl methacrylate) blocks, monitored film thicknesses during annealing, and characterized film morphologies with atomic force microscopy. Morphological changes across the gradients such as the transformation from parallel cylinders to spheres with increasing solvent selectivity provided insight into thin film self-assembly, and the gradient device has enabled us to determine transition compositions and/or concentrations.

  10. The chemistry of nonaqueous solvents v.4 solution phenomena and aprotic solvents

    CERN Document Server

    Lagowski, J J

    1976-01-01

    The Chemistry of Nonaqueous Solvents, Volume IV: Solution Phenomena and Aprotic Solvents focuses on the chemistry of nonaqueous solvents, with emphasis on solution phenomena and aprotic solvents such as tetramethylurea, inorganic acid chlorides, cyclic carbonates, and sulfolane. This book is organized into seven chapters and begins with an overview of the theory of electrical conductivity and elementary experimental considerations, along with some of the interesting research on nonaqueous solvents. It then turns to a discussion on hydrogen bonding phenomena in nonaqueous systems as probed

  11. Mesoscopic aspects of phase transitions in a solvent extraction system.

    Science.gov (United States)

    Ellis, Ross J; Audras, Matthieu; Antonio, Mark R

    2012-11-06

    In liquid-liquid extraction, organic phase splitting arises when high concentrations of polar solutes (acids/metal ions) are extracted. Herein, we investigate the mesoscopic roots that underpin phase splitting in alkane phases containing mixed amphiphiles, of contemporary interest in solvent extraction separation systems, by extracting various oxoacids. The oxoacids exhibited individual macroscopic (extractive and physical) behaviors, inducing phase splitting into heavy and light domains under markedly different conditions. Using small-angle X-ray scattering (SAXS) data analyzed using the generalized indirect Fourier transform (GIFT) method, we showed that, in all cases, acid extraction drove the self-assembly of reverse micelles into rods. These grew with increased acid extraction until reaching a critical length of 20 nm, at which point interactions produced interconnected cylinders or lamellar sheets that prelude phase splitting into heavy and light domains. In all cases, the heavy phase contained the same surfactant ratio-TBP (tri-n-butyl phosphate) and CMPO (octyl(phenyl)-N,N-diisobutylcarbamoylmethylphosphine oxide)-even though the concentrations of acid, water, and amphiphiles were markedly different. The remarkable similarities in structure and amphiphile stoichiometries underpinning phase splitting across the macroscopically different acid extraction series allude to the mesoscopic roots of organic phase behavior in solvent extraction. Our studies show that the structures underpinning phase splitting in solvent extraction systems are more complex than previously thought and are reminiscent of phase transitions in soft matter.

  12. Rapid analysis of pyrethroid insecticides in aquaculture seawater samples via membrane-assisted solvent extraction coupled with gas chromatography-electron capture detection

    OpenAIRE

    Shi, X.Z.; Song, S.Q.; Sun, A.L.; Liu, J.H.; Li, D.X.; Chen, J.

    2012-01-01

    A simple, efficient, and environmentally friendly membrane-assisted solvent extraction (MASE) method for the extraction and preconcentration of six pyrethroid insecticides from aquaculture seawater samples followed by gas chromatography-electron capture detection (GC-ECD) was successfully proposed. The operating conditions for MASE, such as the extraction solvent, solvent volume, NaCl concentration, stirring rate, extraction time, and temperature, were optimized. Compared to conventional Flor...

  13. Experiment on the treatment of waste extraction solvent from the molybdenum-99 process

    Energy Technology Data Exchange (ETDEWEB)

    Hsien-Ming Hsiao; Chang-Liang Hu; Kuang-Li Chien; Wen-Cheng Lee; Tsong-Yang Wei [Division of Chemical Engineering, Institute of Nuclear Energy Research, P.O. Box 3-7, Longtan 32546 Taiwan (China)

    2013-07-01

    In the Mo-99 (Molybdenum-99) isotope extraction test process for radiopharmaceutical applications, organic solvent is used to extract Mo-99 from an irradiated UO{sub 2} dissolution. The extraction solvent was stored when the test work was stopped. A total of about 120 liters of waste solvent was stored at INER (Institute of Nuclear Energy Research, Taiwan). The extraction solvent consisted of 5% di-(2-ethylhexyl)-phosphoric acid (D2EHPA) and kerosene. The radionuclides found in the waste solvent include Cs-137, Am-241, Tc-99, and Sr-90, which give off gross alpha and beta radioactivity of 1898 and 471 Bq/ml, respectively. This study aims to remove radionuclides from the waste solvent using sodium carbonate and sodium hydroxide solutions in different concentrations. After mixing the waste solvent with the alkaline solution followed by settling, a third phase other than organic and aqueous phase appeared which is expected due to the saponification reaction. The experimental results showed that increasing the number of washing and the alkaline solution concentration could enhance the radionuclides removal rate. An optimal removal method was proposed using 2 M Na{sub 2}CO{sub 3} solution twice followed by 1 M NaOH solution one time for the third phase generated early in the mixing stages. The remaining gross alpha and beta radioactivity of the treated organic solvent was 2 and 3 Bq/ml, respectively. The treated solvent could be stabilized by ashing at 500 deg. C and then immobilized. The alkaline solution would be neutralized by hydrochloric or nitric acid and then treated using a variety of adsorbents or bone char via adsorption to remove nuclides to meet the wastewater discharge limitation. (authors)

  14. IUPAC-NIST Solubility Data Series. 98. Solubility of Polycyclic Aromatic Hydrocarbons in Pure and Organic Solvent Mixtures: Revised and Updated. Part 2. Ternary Solvent Mixtures

    Science.gov (United States)

    Acree, William E.

    2013-03-01

    This work updates Vols. 54, 58, and 59 in the IUPAC Solubility Data Series and presents solubility data for polycyclic aromatic hydrocarbon solutes dissolved in ternary organic solvent mixtures. Published solubility data for anthracene, phenanthrene, and pyrene that appeared in the primary literature between 1995 to the end of 2011 are compiled and critically evaluated. Experimental solubility data for 119 different solute-ternary solvent systems are included in the volume. Solubility data published prior to 1995 were contained in three earlier volumes (Vols. 54, 58, and 59) and are not repeated here.

  15. IUPAC-NIST Solubility Data Series. 98. Solubility of Polycyclic Aromatic Hydrocarbons in Pure and Organic Solvent Mixtures--Revised and Updated. Part 3. Neat Organic Solvents

    Science.gov (United States)

    Acree, William E.

    2013-03-01

    This work updates Vols. 54, 58, and 59 in the IUPAC Solubility Data Series and presents solubility data for polycyclic aromatic hydrocarbon solutes dissolved in neat organic solvents. Published solubility data for acenaphthene, anthracene, biphenyl, carbazole, dibenzofuran, dibenzothiophene, fluoranthene, fluorene, naphthalene, phenanthrene, phenothiazine, pyrene, thianthrene, and xanthene that appeared in the primary literature from 1995 to the end of 2011 are compiled and critically evaluated. Experimental solubility data for more than 550 different solute-organic solvent systems are included. Solubility data published prior to 1995 were contained in three earlier volumes (Vols. 54, 58, and 59) and are not repeated in this volume.

  16. IUPAC-NIST Solubility Data Series. 98. Solubility of Polycyclic Aromatic Hydrocarbons in Pure and Organic Solvent Mixtures: Revised and Updated. Part 1. Binary Solvent Mixtures

    Science.gov (United States)

    Acree, William E.

    2013-03-01

    This work updates Vols. 54, 58, and 59 in the IUPAC Solubility Data Series and presents solubility data for polycyclic aromatic hydrocarbon solutes dissolved in binary organic solvent mixtures. Published solubility data for anthracene, naphthalene, phenanthrene, phenothiazine, and pyrene that appeared in the primary literature between 1995 to the end of 2011 are compiled and critically evaluated. Experimental solubility data for 360 different solute-binary solvent systems are included in the volume. Solubility data published prior to 1995 were contained in three earlier volumes (Vols. 54, 58, and 59) and are not repeated in this volume.

  17. Predicting the Solubility of Pharmaceutical Cocrystals in Solvent/Anti-Solvent Mixtures

    Directory of Open Access Journals (Sweden)

    Linda Lange

    2016-05-01

    Full Text Available In this work, the solubilities of pharmaceutical cocrystals in solvent/anti-solvent systems were predicted using PC-SAFT in order to increase the efficiency of cocrystal formation processes. Modeling results and experimental data were compared for the cocrystal system nicotinamide/succinic acid (2:1 in the solvent/anti-solvent mixtures ethanol/water, ethanol/acetonitrile and ethanol/ethyl acetate at 298.15 K and in the ethanol/ethyl acetate mixture also at 310.15 K. The solubility of the investigated cocrystal slightly increased when adding small amounts of anti-solvent to the solvent, but drastically decreased for high anti-solvent amounts. Furthermore, the solubilities of nicotinamide, succinic acid and the cocrystal in the considered solvent/anti-solvent mixtures showed strong deviations from ideal-solution behavior. However, by accounting for the thermodynamic non-ideality of the components, PC-SAFT is able to predict the solubilities in all above-mentioned solvent/anti-solvent systems in good agreement with the experimental data.

  18. Critical Care

    Science.gov (United States)

    Critical care helps people with life-threatening injuries and illnesses. It might treat problems such as complications from surgery, ... attention by a team of specially-trained health care providers. Critical care usually takes place in an ...

  19. Electrochemical Solvent Reorganization Energies in the Framework of the Polarizable Continuum Model.

    Science.gov (United States)

    Ghosh, Soumya; Horvath, Samantha; Soudackov, Alexander V; Hammes-Schiffer, Sharon

    2014-05-13

    Electron transfer reactions at electrochemical interfaces play a critical role in a wide range of catalytic processes. A key parameter in the rate constant expressions for such processes is the reorganization energy, which reflects the energetic cost of the solute and solvent rearrangements upon electron transfer. In this paper, we present dielectric continuum methods for calculating the solvent reorganization energy for electrochemical processes. We develop a method for calculating the electrochemical solvent reorganization energies with molecular-shaped cavities within the framework of the polarizable continuum model (PCM). The electronic and inertial responses of the solvent are separated according to their respective time scales, and two limiting cases of the relation between the solute and solvent electrons are examined. The effects of the electrode are included with the integral equations formalism PCM (IEF-PCM), in which the molecule-solvent boundary is treated explicitly, but the effects of the electrode-solvent boundary are included through an external Green's function. This approach accounts for the effects of detailed molecular charge redistribution in a molecular-shaped cavity, as well as the electronic and inertial solvent responses and the effects of the electrode. The calculated total reorganization energies are in reasonable agreement with experimental measurements for a series of electrochemical systems. Inclusion of the effects of the electrode is found to be essential for obtaining even qualitatively accurate solvent reorganization energies. These approaches are applicable to a wide range of systems and can be extended to include other types of boundaries, such as a self-assembled monolayer or double layer separating the electrode and the molecule.

  20. ACCELERATED SOLVENT EXTRACTION COMBINED WITH ...

    Science.gov (United States)

    A research project was initiated to address a recurring problem of elevated detection limits above required risk-based concentrations for the determination of semivolatile organic compounds in high moisture content solid samples. This project was initiated, in cooperation with the EPA Region 1 Laboratory, under the Regional Methods Program administered through the ORD Office of Science Policy. The aim of the project was to develop an approach for the rapid removal of water in high moisture content solids (e.g., wetland sediments) in preparation for analysis via Method 8270. Alternative methods for water removal have been investigated to enhance compound solid concentrations and improve extraction efficiency, with the use of pressure filtration providing a high-throughput alternative for removal of the majority of free water in sediments and sludges. In order to eliminate problems with phase separation during extraction of solids using Accelerated Solvent Extraction, a variation of a water-isopropanol extraction method developed at the USGS National Water Quality Laboratory in Denver, CO is being employed. The concentrations of target compounds in water-isopropanol extraction fluids are subsequently analyzed using an automated Solid Phase Extraction (SPE)-GC/MS method developed in our laboratory. The coupled approaches for dewatering, extraction, and target compound identification-quantitation provide a useful alternative to enhance sample throughput for Me

  1. Perpendicular Structure Formation of Block Copolymer Thin Films during Thermal Solvent Vapor Annealing: Solvent and Thickness Effects

    Directory of Open Access Journals (Sweden)

    Qiuyan Yang

    2017-10-01

    Full Text Available Solvent vapor annealing of block copolymer (BCP thin films can produce a range of interesting morphologies, especially when the perpendicular orientation of micro-domains with respect to the substrate plays a role. This, for instance, allows BCP thin films to serve as useful templates for nanolithography and hybrid materials preparation. However, precise control of the arising morphologies is essential, but in most cases difficult to achieve. In this work, we investigated the solvent and thickness effects on the morphology of poly(styrene-b-2 vinyl pyridine (PS-b-P2VP thin films with a film thickness range from 0.4 L0 up to 0.8 L0. Ordered perpendicular structures were achieved. One of the main merits of our work is that the phase behavior of the ultra-high molecular weight BCP thin films, which hold a 100-nm sized domain distance, can be easily monitored via current available techniques, such as scanning electron microscope (SEM, atomic force microscope (AFM, and transmission electron microscope (TEM. Systematic monitoring of the self-assembly behavior during solvent vapor annealing can thus provide an experimental guideline for the optimization of processing conditions of related BCP films systems.

  2. The A Priori Design and Selection of Ionic Liquids as Solvents for Active Pharmaceutical Ingredients

    DEFF Research Database (Denmark)

    Kunov-Kruse, Andreas Jonas; Weber, Cameron C.; Rogers, Robin D.

    2017-01-01

    In this paper we derive a straightforward computational approach to predict the optimal ionic liquid (IL) solvent for a given compound, based on COSMO-RS calculations. These calculations were performed on 18 different active pharmaceutical ingredients (APIs) using a matrix of 210 hypothetical ILs...

  3. Enzymatic Lipophilization of Phenolic Acids through Esterification with Fatty Alcohols in Organic Solvents

    DEFF Research Database (Denmark)

    Yang, Zhiyong; Guo, Zheng; Xu, Xuebing

    2012-01-01

    In this study, we investigated and optimized the synthesis of lipophilized esters between selected phenolic acids and fatty alcohols in a binary solvent system, which is composed of hexane and butanone. The effect of different proportion of hexane and butanone was firstly studied by changing the ...

  4. Organic Solvent Tolerant Lipases and Applications

    Directory of Open Access Journals (Sweden)

    Shivika Sharma

    2014-01-01

    Full Text Available Lipases are a group of enzymes naturally endowed with the property of performing reactions in aqueous as well as organic solvents. The esterification reactions using lipase(s could be performed in water-restricted organic media as organic solvent(s not only improve(s the solubility of substrate and reactant in reaction mixture but also permit(s the reaction in the reverse direction, and often it is easy to recover the product in organic phase in two-phase equilibrium systems. The use of organic solvent tolerant lipase in organic media has exhibited many advantages: increased activity and stability, regiospecificity and stereoselectivity, higher solubility of substrate, ease of products recovery, and ability to shift the reaction equilibrium toward synthetic direction. Therefore the search for organic solvent tolerant enzymes has been an extensive area of research. A variety of fatty acid esters are now being produced commercially using immobilized lipase in nonaqueous solvents. This review describes the organic tolerance and industrial application of lipases. The main emphasis is to study the nature of organic solvent tolerant lipases. Also, the potential industrial applications that make lipases the biocatalysts of choice for the present and future have been presented.

  5. Environmental Impacts on Nuclear Reprocessing Solvents

    Science.gov (United States)

    Gillens, A. R.; Fessenden, J. E.

    2009-12-01

    Nuclear tests have been employed ever since the first nuclear explosion in Alamogordo, NM during the mid-1940s. Nuclear weapons pose a threat to civil society and result in extensive biological (medical) damages. For this reason, treaties banning nuclear tests and weapons have been employed since the 1960s to cease proliferation of weapons. However, as nuclear tests continue in secrecy and actinides, such as plutonium and uranium, are eligible for theft, nuclear forensics is needed to prevent weapons proliferation. In this study, solvents [tributyl phosphate (TBP), dodecane, decanol] used in reprocessing spent nuclear fuel are analyzed using an isotope ratio mass spectrometer, which provides indisputable evidence in identifying the operation in which solvents were used. Solvent samples are observed under variable conditions in the laboratory for different time periods. It is assumed that their carbon isotope values (δ13C) will become more positive (shift heavy) with time. It is found that the solvents are hygroscopic. TBP leaves the most robust signature compared to the other solvents studied and the isotope values for all solvents under all conditions become more positive with time. This study serves as primary research in understanding how solvents behave under variable conditions in the laboratory and how this could be translated to the environment in fate and transport studies.

  6. Solvent Effect on the Photolysis of Riboflavin.

    Science.gov (United States)

    Ahmad, Iqbal; Anwar, Zubair; Ahmed, Sofia; Sheraz, Muhammad Ali; Bano, Raheela; Hafeez, Ambreen

    2015-10-01

    The kinetics of photolysis of riboflavin (RF) in water (pH 7.0) and in organic solvents (acetonitrile, methanol, ethanol, 1-propanol, 1-butanol, ethyl acetate) has been studied using a multicomponent spectrometric method for the assay of RF and its major photoproducts, formylmethylflavin and lumichrome. The apparent first-order rate constants (k obs) for the reaction range from 3.19 (ethyl acetate) to 4.61 × 10(-3) min(-1) (water). The values of k obs have been found to be a linear function of solvent dielectric constant implying the participation of a dipolar intermediate along the reaction pathway. The degradation of this intermediate is promoted by the polarity of the medium. This indicates a greater stabilization of the excited-triplet states of RF with an increase in solvent polarity to facilitate its reduction. The rate constants for the reaction show a linear relation with the solvent acceptor number indicating the degree of solute-solvent interaction in different solvents. It would depend on the electron-donating capacity of RF molecule in organic solvents. The values of k obs are inversely proportional to the viscosity of the medium as a result of diffusion-controlled processes.

  7. Chemical reactions in solvents and melts

    CERN Document Server

    Charlot, G

    1969-01-01

    Chemical Reactions in Solvents and Melts discusses the use of organic and inorganic compounds as well as of melts as solvents. This book examines the applications in organic and inorganic chemistry as well as in electrochemistry. Organized into two parts encompassing 15 chapters, this book begins with an overview of the general properties and the different types of reactions, including acid-base reactions, complex formation reactions, and oxidation-reduction reactions. This text then describes the properties of inert and active solvents. Other chapters consider the proton transfer reactions in

  8. Genomic and Genetic Approaches to Solvent Tolerance

    Energy Technology Data Exchange (ETDEWEB)

    Eleftherios T. Papoutsakis

    2005-06-10

    The proposed research is to understand and exploit the molecular basis that determines tolerance of the industrially important anaerobic clostridia to solvents. Furthermore, we aim to develop general genomic and metabolic engineering strategies for understanding the molecular basis of tolerance to chemicals and for developing tolerant strains. Our hypothesis is that the molecular basis of what makes bacterial cells able to withstand high solvent concentrations can be used to metabolically engineer cells so that they can tolerate higher concentrations of solvents and related chemicals.

  9. A Spreadsheet Algorithm for Stagewise Solvent Extraction

    Energy Technology Data Exchange (ETDEWEB)

    Leonard, R.A.; Regalbuto, M.C.

    1993-08-01

    The material balance and equilibrium equations for solvent extraction processes have been combined with computer spreadsheets in a new way so that models for very complex multicomponent multistage operations can be setup and used easily. A part of the novelty is the way in which the problem is organized in the spreadsheet. In addition, to facilitate spreadsheet setup, a new calculational procedure has been developed. The resulting Spreadsheet Algorithm for Stagewise Solvent Extraction (SASSE) can be used with either IBM or Macintosh personal computers as a simple yet powerful tool for analyzing solvent extraction flowsheets.

  10. TRUEX process solvent cleanup with solid sorbents

    Energy Technology Data Exchange (ETDEWEB)

    Tse, Pui-Kwan; Reichley-Yinger, L.; Vandegrift, G.F.

    1989-01-01

    Solid sorbents, alumina, silica gel, and Amberlyst A-26 have been tested for the cleanup of degraded TRUEX-NPH solvent. A sodium carbonate scrub alone does not completely remove acidic degradation products from highly degraded solvent and cannot restore the stripping performance of the solvent. By following the carbonate scrub with either neutral alumina or Amberlyst A-26 anion exchange resin, the performance of the TRUEX-NPH is substantially restored. The degraded TRUEX-NPH was characterized before and after treatment by supercritical fluid chromatography. Its performance was evaluated by americium distribution ratios, phase-separation times, and lauric acid distribution coefficients. 17 refs., 2 figs., 5 tabs.

  11. Modeling of Salt Solubilities in Mixed Solvents

    DEFF Research Database (Denmark)

    Chiavone-Filho, O.; Rasmussen, Peter

    2000-01-01

    constants and the liquid densities of the solvent media. To normalize the activity coefficients, the symmetric convention is adopted. Thermochemical properties of the salt are used to estimate the solubility product. It is shown that the proposed procedure can describe with good accuracy a series of salt......A method to correlate and predict salt solubilities in mixed solvents using a UNIQUAC+Debye-Huckel model is developed. The UNIQUAC equation is applied in a form with temperature-dependent parameters. The Debye-Huckel model is extended to mixed solvents by properly evaluating the dielectric...

  12. Agglomeration of celecoxib by quasi-emulsion solvent diffusion method without stabilizer: effect of good solvent.

    Science.gov (United States)

    Maghsoodi, Maryam; Nokhodchi, Ali

    2017-01-12

    The aim of the present research is to investigate the feasibility of agglomeration of crystals by the quasi-emulsion solvent diffusion method without using a stabilizer. Two solvent systems comprising a solvent and an antisolvent (water) were used to prepare celecoxib agglomerates. To this end, seven solvents including propanol, methyl acetate, methyl ethyl ketone, butanol, ethyl acetate, isopropyl acetate, and pentanol were examined. The agglomerates were evaluated by micromeritic properties (e.g., size, density, flowability), yield, drug physical state, friability, and dissolution behavior. In the present study the clear trend was observed experimentally in the agglomerate properties as a function of physical properties of the solvent such as miscibility with water. Solvents with high water miscibility (25% v/v) resulted in sticky and hollow particles, while solvents with low water miscibility (3%v/v) led to the formation of agglomerates with low strength. However, the agglomerates made from the solvents with intermediate water miscibility (10% v/v), may reflect a greater integrity of the agglomerates regarding yield and strength. Results of this study offer a useful starting point for a conceptual framework to guide the selection of solvent systems for the quasi-emulsion solvent diffusion method without using a stabilizer.

  13. How Critical Is Critical Thinking?

    Science.gov (United States)

    Shaw, Ryan D.

    2014-01-01

    Recent educational discourse is full of references to the value of critical thinking as a 21st-century skill. In music education, critical thinking has been discussed in relation to problem solving and music listening, and some researchers suggest that training in critical thinking can improve students' responses to music. But what exactly is…

  14. Optimization and Optimal Control

    CERN Document Server

    Chinchuluun, Altannar; Enkhbat, Rentsen; Tseveendorj, Ider

    2010-01-01

    During the last four decades there has been a remarkable development in optimization and optimal control. Due to its wide variety of applications, many scientists and researchers have paid attention to fields of optimization and optimal control. A huge number of new theoretical, algorithmic, and computational results have been observed in the last few years. This book gives the latest advances, and due to the rapid development of these fields, there are no other recent publications on the same topics. Key features: Provides a collection of selected contributions giving a state-of-the-art accou

  15. On the Integration Role of Solvents in Process Synthesis-Design-Intensification: Application to DMC/MeOH separation

    DEFF Research Database (Denmark)

    Gani, Rafiqul; Babi, Deenesh Kavi

    2015-01-01

    Solvents (mass separating agents) play an important role in separation-based processes. For example, consider the separation of an azeotropic mixture. If the azeotrope is not pressure dependent, then a feasible separation technique that can be employed for separation of the azeotrope is usually...... and the heavier boiling compound is obtained as the top product of the second distillation column where the solvent is recovered (for re-use and recycle). Therefore, the solvent design problem can be defined as follows, given an azeotropic mixture to be separated into two pure streams that utilizes a mass...... separating agent, find the best (optimal or near-optimal) solvent candidate (or mixture) that can perform the separation subject to economic, environmental and thermo-physical property constraints. This design problem inherently is a mixed integer non-linear programming problem because the property...

  16. Extraction of Illegal Dyes from Red Chili Peppers with Cholinium-Based Deep Eutectic Solvents

    Directory of Open Access Journals (Sweden)

    Shuqiang Zhu

    2017-01-01

    Full Text Available Deep eutectic solvents (DESs as a new kind of green solvents have been used to extract bioactive compounds but there are few applications in extracting chrysoidine dyes. In this study, we developed an ultrasonic-assisted extraction method with choline chloride/hydrogen bond donor (ChCl/HBD DES for the extraction of chrysoidine G (COG, astrazon orange G (AOG, and astrazon orange R (AOR in food samples. Some experimental parameters, such as extraction time, raw material/solvent ratio, and temperature, were evaluated and optimized as follows: the ratio of ChCl/HBD, 1 : 2 (v/v; the ratio of sample/DES, 1 : 10 (g/mL; extraction time, 20 min; extraction temperature, 50°C. Under the optimized conditions, the limits of detection (μg/mL were 0.10 for COG and 0.06 for AOG and AOR. The relative standard deviations were in the range of 1.2–2.1%. The recoveries of the three dyes were in the range of 80.2–105.0%. By comparing with other commonly used solvents for extracting chrysoidine dyes, the advantages of DESs proved them to be potential extraction solvents for chrysoidine G, astrazon orange G, and astrazon orange R in foods.

  17. [Simultaneous determination of seven residual solvents in bovis calculus artifactus by headspace gas chromatography].

    Science.gov (United States)

    Chi, Shuyao; Wu, Dike; Sun, Jinhong; Ye, Ruhan; Wang, Xiaoyan

    2014-05-01

    A headspace gas chromatography (HS-GC) method was developed for the simultaneous determination of seven residual solvents (petroleum ether (60-90 degrees C), acetone, ethyl acetate, methanol, methylene chloride, ethanol and butyl acetate) in bovis calculus artifactus. The DB-WAX capillary column and flame ionization detector (FID) were used for the separation and detection of the residual solvents, and the internal standard method was used for the quantification. The chromatographic conditions, such as equilibrium temperature and equilibrium time, were optimized. Under the optimized conditions, all of the seven residual solvents showed good linear relationships with good correlation coefficients (not less than 0.999 3) in the prescribed concentration range. At three spiked levels, the recoveries for the seven residual solvents were 94.7%-105.2% with the relative standard deviations (RSDs) less than 3.5%. The limits of detection (LODs) of the method were 0.43-5.23 mg/L, and the limits of quantification (LOQs) were 1.25-16.67 mg/L. The method is simple, rapid, sensitive and accurate, and is suitable for the simultaneous determination of the seven residual solvents in bovis calculus artifactus.

  18. Solvent induced supramolecular anisotropy in molecular gels

    Energy Technology Data Exchange (ETDEWEB)

    Rogers, Michael A., E-mail: mroger09@uoguelph.ca [Department of Food Science, University of Guelph, Guelph, Ontario, N3C3X9 (Canada); Corradini, Maria G. [Department of Food Science, University of Massachusetts Amherst, Amherst, MA, 01003 (United States); Emge, Thomas [Department of Chemistry and Biochemistry, Rutgers University, New Brunswick, NJ, 08901 (United States)

    2017-06-15

    Herein is the first report of solvent induced anisotropy in 12-hydroxystearic acid self-assembled fibrillar networks. Increasing the chain length of polar solvent, such as nitriles and ketones, tailored the anisotropy of the fibrillar aggregates. 12HSA molecular gels, comprised of alkanes, exhibited an isotropic fibrillar network irrespective of the alkane chain length. In polar solvents, anisotropy, observed using 2D powder x-ray diffraction profiles, is correlated to a fibrillar supramolecular morphologies in long chain nitriles and ketones while sphereulitic crystals are correlated to x-ray diffraction patterns with an isotropic scatter intensity in short chain ketones and nitriles. These changes directly modify the final physical properties of the gels. - Highlights: • 12-HSA self-assembles into crystalline supramolecular morphologies depending on the solvent. • Alkanes, short chain nitriles and ketones led to 12-HSA displaying supramolecular isotropy. • In long chain nitriles and ketones, 12-HSA displays supramolecular anisotropy.

  19. Computer-aided solvent screening for biocatalysis

    NARCIS (Netherlands)

    Abildskov, J.; Leeuwen, van M.B.; Boeriu, C.G.; Broek, van den L.A.M.

    2013-01-01

    A computer-aidedsolventscreening methodology is described and tested for biocatalytic systems composed of enzyme, essential water and substrates/products dissolved in a solvent medium, without cells. The methodology is computationally simple, using group contribution methods for calculating

  20. Computer-Aided Solvent Screening for Biocatalysis

    DEFF Research Database (Denmark)

    Abildskov, Jens; Leeuwen, M.B. van; Boeriu, C.G.

    2013-01-01

    constrained properties related to chemical reaction equilibrium, substrate and product solubility, water solubility, boiling points, toxicity and others. Two examples are provided, covering the screening of solvents for lipase-catalyzed transesterification of octanol and inulin with vinyl laurate...

  1. SHORT COMMUNICATION SOLVENT FREE PREPARATION OF N ...

    African Journals Online (AJOL)

    Preferred Customer

    carboxy, 4-bromo, 4- hydroxy, 3-hydroxy, 4-chloro and ... KEYWORDS: Solvent free, Maleanilic acids, Maleic anhydride, Aniline derivatives ... vibration, also referred to as the amide II bands and are characterized to primary and secondary amide [16].

  2. Solvent selectivity studies using isomers of polystyrene

    Energy Technology Data Exchange (ETDEWEB)

    Men, L.C.; Na, H.; Rogers, L.B.

    1984-01-01

    The order of elution of isomeric trimers of polystyrene has been found to be independent of the dominant solvent-solute interaction as indicated by the location of the solvent in a Snyder triangle. The pure solvents were nitromethane, propylene carbonate, N-methylformamide, acetonitrile, the mixtures were trifluoroethanol with chloroform, methylene chloride and trichlorotrifluoroethane and also one of 2-methoxyethanol with water. Likewise, mixtures of acetonitrile with solvents near each of the corners of that triangle (chloroform, methylene chloride, and trifluoroethanol did not change the order of isomer elution). Substitution of trifluoroethanol for ethanol in mixtures with chloroform, methylene chloride, or trichlorotrifluoroethane led to improved isomer fractionations. 3 references, 5 figures, 2 tables.

  3. Optimization of an Agitated Extractor

    Directory of Open Access Journals (Sweden)

    Evan Zapf

    2016-05-01

    Full Text Available In this scenario, we use calculus to determine the optimal operating specifications of a chemical extraction process. The results are achieved by first developing an expression that yields the total annual cost of the process. Factoring in electricity, vessel, agitator, and solvent costs, an annual cost expression was fabricated. AGIEX company manufactures a certain amount of a product, A, which has an impurity that it wishes be reduced. By engineering an optimally sized vessel to perform the extraction of impurity, the company will save costs by ensuring no inefficient spending on power or excess solvent occurs. A specific amount of electricity is required to operate this vessel during extraction batches. These values of optimal vessel volume and power usage per batch ultimately form the boundaries of this streamlined system for the company.

  4. Critical Jostling

    Directory of Open Access Journals (Sweden)

    Pippin Barr

    2016-11-01

    Full Text Available Games can serve a critical function in many different ways, from serious games about real world subjects to self-reflexive commentaries on the nature of games themselves. In this essay we discuss critical possibilities stemming from the area of critical design, and more specifically Carl DiSalvo’s adversarial design and its concept of reconfiguring the remainder. To illustrate such an approach, we present the design and outcomes of two games, Jostle Bastard and Jostle Parent. We show how the games specifically engage with two previous games, Hotline Miami and Octodad: Dadliest Catch, reconfiguring elements of those games to create interactive critical experiences and extensions of the source material. Through the presentation of specific design concerns and decisions, we provide a grounded illustration of a particular critical function of videogames and hope to highlight this form as another valuable approach in the larger area of videogame criticism.

  5. Critical Evaluations and Thermodynamic Optimizations of the MnO-Mn2O3-SiO2 and FeO-Fe2O3-MnO-Mn2O3-SiO2 Systems

    Science.gov (United States)

    Kang, Youn-Bae; Jung, In-Ho

    2017-06-01

    A critical evaluation and thermodynamic modeling for thermodynamic properties of all oxide phases and phase diagrams in the Fe-Mn-Si-O system (MnO-Mn2O3-SiO2 and FeO-Fe2O3-MnO-Mn2O3-SiO2 systems) are presented. Optimized Gibbs energy parameters for the thermodynamic models of the oxide phases were obtained which reproduce all available and reliable experimental data within error limits from 298 K (25°C) to above the liquidus temperatures at all compositions covering from known oxide phases, and oxygen partial pressure from metal saturation to 0.21 bar. The optimized thermodynamic properties and phase diagrams are believed to be the best estimates presently available. Slag (molten oxide) was modeled using the modified quasichemical model in the pair approximation. Olivine (Fe2SiO4-Mn2SiO4) was modeled using two-sublattice model in the framework of the compound energy formalism (CEF), while rhodonite (MnSiO3-FeSiO3) and braunite (Mn7SiO_{12} with excess Mn2O3) were modeled as simple Henrian solutions. It is shown that the already developed models and databases of two spinel phases (cubic- and tetragonal-(Fe, Mn)3O4) using CEF [Kang and Jung, J. Phys. Chem. Solids (2016), vol. 98, pp. 237-246] can successfully be integrated into a larger thermodynamic database to be used in practically important higher order system such as silicate. The database of the model parameters can be used along with a software for Gibbs energy minimization in order to calculate any type of phase diagram section and thermodynamic properties.

  6. Micellization and interfacial behavior of imidazolium-based ionic liquids in organic solvent-water mixtures.

    Science.gov (United States)

    Pino, Verónica; Yao, Cong; Anderson, Jared L

    2009-05-15

    The surface and micellar properties of aqueous solutions of two imidazolium-based ionic liquids (ILs), 1-hexadecyl-3-butylimidazolium bromide (HDBIm-Br) and 1,3-didodecylimidazolium bromide (DDDDIm-Br), are examined in the presence of several organic solvents by surface tensiometry. The organic solvents studied include methanol, 1-propanol, 1-butanol, 1-pentanol, and acetonitrile. Increases in the critical micelle concentration (cmc) values were obtained for both ILs when increasing the organic solvent content with a more significant increase observed for the DDDDIm-Br IL. For both ILs, decreases in the maximum surface excess concentration (Gamma(max)), increases in the minimum surface area per surfactant molecule (A(min)), decreases in the adsorption efficiency (pC(20)), and decreases in the effectiveness of surface tension reduction (Pi(cmc)) were obtained when increasing the organic solvent content. However, the studied organic solvents affect the surface tension at the cmc (gamma(cmc)) differently; generating increases for DDDDIm-Br and decreases for HDBIm-Br. These changes can be linked to the different water-air interface orientation of both ILs in aqueous solutions free of organic solvents. Linear correlations between the extent of the change in these parameters when increasing the alkyl-chain of the alcohol modifier were also observed. A preliminary study of the utilization of HDBIm-Br in micellar-liquid chromatography (MLC) is also presented, demonstrating the applicability of the IL-aggregates in this analytical technique.

  7. Computer-Aided Solvent Screening for Biocatalysis

    OpenAIRE

    Abildskov, Jens; Leeuwen, M.B. van; Boeriu, C.G.; Broek, L.A.M. van den

    2013-01-01

    A computer-aided solvent screening methodology is described and tested for biocatalytic systems composed of enzyme, essential water and substrates/products dissolved in a solvent medium, without cells. The methodology is computationally simple, using group contribution methods for calculating constrained properties related to chemical reaction equilibrium, substrate and product solubility, water solubility, boiling points, toxicity and others. Two examples are provided, covering the screening...

  8. Solvent Extraction and Ion Exchange in Radiochemistry

    Science.gov (United States)

    Skarnemark, G.

    In 1805, Bucholz extracted uranium from a nitric acid solution into ether and back-extracted it into pure water. This is probably the first reported solvent-extraction investigation. During the following decades, the distribution of neutral compounds between aqueous phases and pure solvents was studied, e.g., by Peligot, Berthelot and Jungfleisch, and Nernst. Selective extractants for analytical purposes became available during the first decades of the twentieth century. From about 1940, extractants such as organophosphorous esters and amines were developed for use in the nuclear fuel cycle. This connection between radiochemistry and solvent-extraction chemistry made radiochemists heavily involved in the development of new solvent extraction processes, and eventually solvent extraction became a major separation technique in radiochemistry. About 160 years ago, Thompson and Way observed that soil can remove potassium and ammonium ions from an aqueous solution and release calcium ions. This is probably the first scientific report on an ion-exchange separation. The first synthesis of the type of organic ion exchangers that are used today was performed by Adams and Holmes in 1935. Since then, ion-exchange techniques have been used extensively for separations of various radionuclides in trace as well as macro amounts. During the last 4 decades, inorganic ion exchangers have also found a variety of applications. Today, solvent extraction as well as ion exchange are used extensively in the nuclear industry and for nuclear, chemical, and medical research. Some of these applications are discussed in the chapter.

  9. CHEMICAL STABILITY OF POLYPHENYLENE SULFIDE IN THE NEXT GENERATION SOLVENT FOR CAUSTIC-SIDE SOLVENT EXTRACTION

    Energy Technology Data Exchange (ETDEWEB)

    Fondeur, F.; Fink, S.

    2011-12-08

    The Office of Waste Processing, within the Office of Technology Innovation and Development, is funding the development of an enhanced solvent for deployment at the Savannah River Site for removal of cesium from High Level Waste. For simplicity, this solvent is referred to as the Next Generation Solvent (NGS). The technical effort is collaboration between Oak Ridge National Laboratory (ORNL), Savannah River National Laboratory (SRNL), and Argonne National Laboratory. The initial deployment target envisioned for the technology was within the Modular Caustic-Side Solvent Extraction Unit (MCU). Deployment of a new chemical within an existing facility requires verification that the chemical components are compatible with the installed equipment. In the instance of a new organic solvent, the primary focus is on compatibility of the solvent with polyphenylene sulfide (PPS), the polymer used in the coalescers within MCU. This report provides the data from exposing PPS polymer to NGS. The test was conducted over a three month period. PPS is remarkably stable in the presence of the next generation solvent. Testing showed no indication of swelling or significant leaching. Preferential sorption of the Modifier on PPS was observed but the same behavior occurs with the baseline solvent. Therefore, PPS coalescers exposed to the NGS are expected to perform comparably to those in contact with the baseline solvent.

  10. PSE For Solvent Applications: A Generic Computer-aided Solvent Selection and Design Framework

    DEFF Research Database (Denmark)

    Mitrofanov, Igor; Sin, Gürkan; Gani, Rafiqul

    system engineering view that emphasizes a systematic and generic solution framework to solvent selection problems is presented. The framework integrates different methods and tools to manage the complexity and solve a wide range of problems in efficient and flexible manner. Its software implementation...... industry (API solubility), solvents i! ! n formulations and as cleaning agents. The template is expected to guide the average user through the essential and desirable steps in solvent selection and design. The expert may also use the general interface and create their own template for the types of solvent...

  11. Replica Temperatures for Uniform Exchange and Efficient Roundtrip Times in Explicit Solvent Parallel Tempering Simulations.

    Science.gov (United States)

    Prakash, Meher K; Barducci, Alessandro; Parrinello, Michele

    2011-07-12

    The efficiency of parallel tempering simulations is greatly influenced by the distribution of replica temperatures. In explicit solvent biomolecular simulations, where the total energy is dominated by the solvent, specific heat is usually assumed to be constant. From this, it follows that a geometric distribution of temperatures is optimal. We observe that for commonly used water models (TIP3P, SPC/E) under constant volume conditions and in the range of temperatures normally used, the specific heat is not a constant, consistent with experimental observations. Using this fact, we derive an improved temperature distribution which substantially reduces the round-trip times, especially when working with a small number of replicas.

  12. Development of novel purifiers with appropriate functional groups based on solvent polarities at bulk filtration

    Science.gov (United States)

    Kohyama, Tetsu; Kaneko, Fumiya; Ly, Saksatha; Hamzik, James; Jaber, Jad; Yamada, Yoshiaki

    2017-03-01

    Weak-polar solvents like PGMEA (Propylene Glycol Monomethyl Ether Acetate) or CHN (Cyclohexanone) are used to dissolve hydrophobic photo-resist polymers, which are challenging for traditional cleaning methods such as distillation, ion-exchange resins service or water-washing processes. This paper investigated two novel surface modifications to see their effectiveness at metal removal and to understand the mechanism. The experiments yielded effective purification methods for metal reduction, focusing on solvent polarities based on HSP (Hansen Solubility Parameters), and developing optimal purification strategies.

  13. Effect of solvent and PVP on electrode conductivity in laser-induced reduction process

    Science.gov (United States)

    Lee, Huseung; Yang, Minyang

    2015-04-01

    Laser sintering process is a promising technique which can sinter an electrode pattern selectively without mask. In this study, metal oxide nanoparticle with several solvents and various molar ratio of polyvinylpyrrolidone (PVP) is prepared to optimize a fabrication of a copper electrode pattern. As a result, the solvent with exothermic heat flow and low absorption cross-section shows better pattern shape and higher conductivity in selective laser sintering. Additionally, PVP, a reductant, affects to the quality of electrode, too. High molar ratio and large amount of PVP make the laser sintering process window broad and the specific resistivity low.

  14. Biodiesel preparation catalyzed by compound-lipase in co-solvent

    Energy Technology Data Exchange (ETDEWEB)

    Li, Qin; Zheng, Jingjing; Yan, Yunjun [Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan 430074, Hubei Province (China)

    2010-10-15

    Besides high cost, the most important reasons that immobilized lipases are limited in industrialization of biodiesel production are the toxicity of methanol and the adsorption of glycerol onto the surface of immobilized vector. Solvent engineering method was employed to the reaction where compound-lipase with synergistic effect, Novozym 435 and Lipozyme TL IM, catalyzed preparation of biodiesel from stillingia oil with methanol. The treatment accelerated the solubility of methanol in oil and dissolved glycerol, which helped maintain lipase activity. It is found that the yields of biodiesel in co-solvent exceeded those in the pure organic solvents. The mixture system of co-solvent with 60% acetonitrile and 40% t-butanol (v/v) was proved to be an optimal one, and RSM was used to optimize the reaction factors and the optimal conditions: methanol/oil molar ratio 6.4:1, compound-lipase 4.32% (wt/wt) and molecular sieve 5.5% (wt/wt). R{sup 2}= 98.86% showed good coincidence between predicted and experimental values. There was nearly no loss inactivity of compound-lipase after being recycled for 30 times. Other oils were also investigated in the mixture system, and we got the same results, which indicated that the mixture system could be an ideal prospective medium applied to biodiesel production. (author)

  15. Critical Review

    DEFF Research Database (Denmark)

    Rosenbaum, Ralph K.; Olsen, Stig Irving

    2017-01-01

    Manipulation and mistakes in LCA studies are as old as the tool itself, and so is its critical review. Besides preventing misuse and unsupported claims, critical review may also help identifying mistakes and more justifiable assumptions as well as generally improve the quality of a study. It thus...

  16. Critical Muralism

    Science.gov (United States)

    Rosette, Arturo

    2009-01-01

    This study focuses on the development and practices of Critical Muralists--community-educator-artist-leader-activists--and situates these specifically in relation to the Mexican mural tradition of los Tres Grandes and in relation to the history of public art more generally. The study examines how Critical Muralists address artistic and…

  17. The optimal extraction parameters and anti-diabetic activity of ...

    African Journals Online (AJOL)

    diabetic activity of FIBL on alloxan induced diabetic mice were studied. The optimal extraction parameters of FIBL were obtained by single factor test and orthogonal test, as follows: ethanol concentration 60 %, ratio of solvent to raw material 30 ...

  18. Production of Thermostable Organic Solvent Tolerant Keratinolytic Protease from Thermoactinomyces sp. RM4: IAA Production and Plant Growth Promotion.

    Science.gov (United States)

    Verma, Amit; Singh, Hukum; Anwar, Mohammad S; Kumar, Shailendra; Ansari, Mohammad W; Agrawal, Sanjeev

    2016-01-01

    There are several reports about the optimization of protease production, but only few have optimized the production of organic solvent tolerant keratinolytic proteases that show remarkable exploitation in the development of the non-polluting processes in biotechnological industries. The present study was carried with aim to optimize the production of a thermostable organic solvent tolerant keratinolytic protease Thermoactinomyces sp. RM4 utilizing chicken feathers. Thermoactinomyces sp. RM4 isolated from the soil sample collected from a rice mill wasteyard site near Kashipur, Uttrakhand was identified on the basis of 16S rDNA analysis. The production of organic solvent tolerant keratinolytic protease enzyme by Thermoactinomyces sp. RM4 was optimized by varying physical culture conditions such as pH (10.0), temperature (60°C), inoculum percentage (2%), feather concentration (2%) and agitation rate (2 g) for feather degradation. The result showed that Thermoactinomyces sp. RM4 potentially produces extra-cellular thermostable organic solvent tolerant keratinolytic protease in the culture medium. Further, the feather hydrolysate from keratinase production media showed plant growth promoting activity by producing indole-3-acetic acid itself. The present findings suggest that keratinolytic protease from Thermoactinomyces sp. RM4 offers enormous industrial applications due to its organic solvent tolerant property in peptide synthesis, practical role in feather degradation and potential function in plant growth promoting activity, which might be a superior candidate to keep ecosystem healthy and functional.

  19. New Polymeric Membranes for Organic Solvent Nanofiltration

    KAUST Repository

    Aburabie, Jamaliah

    2017-05-01

    The focus of this dissertation was the development, synthesis and modification of polymers for the preparation of membranes for organic solvent nanofiltration. High chemical stability in a wide range of solvents was a key requirement. Membranes prepared from synthesized polymers as well as from commercial polymers were designed and chemically modified to reach OSN requirements. A solvent stable thin-film composite (TFC) membrane is reported, which is fabricated on crosslinked polythiosemicarbazide (PTSC) as substrate. The membranes exhibited high fluxes towards solvents like THF, DMF and DMSO ranging around 20 L/m2 h at 5 bar with a MWCO of around 1000 g/mol. Ultrafiltration PTSC membranes were prepared by non-solvent induced phase separation and crosslinked with GPTMS. The crosslinking reaction was responsible for the formation of an inorganic-type-network that tuned the membrane pore size. The crosslinked membranes acquired high solvent stability in DMSO, DMF and THF with a MWCO above 1300 g/mol. Reaction Induced Phase Separation (RIPS) was introduced as a new method for the preparation of skinned asymmetric membranes. These membranes have two distinctive layers with different morphologies both from the same polymer. The top dense layer is composed of chemically crosslinked polymer chains while the bottom layer is a porous structure formed by non-crosslinked polymer chains. Such membranes were tested for vitamin B12 in solvents after either crosslinking the support or dissolving the support and fixing the freestanding membrane on alumina. Pebax® 1657 was utilized for the preparation of composite membranes by simple coating. Porous PAN membranes were coated with Pebax® 1657 which was then crosslinked using TDI. Crosslinked Pebax® membranes show high stability towards ethanol, propanol and acetone. The membranes were also stable in DMF once crosslinked PAN supports were used. Sodium alginate polymer was investigated for the preparation of thin film composite

  20. Chlorinated solvent replacements recycle/recovery review report

    Energy Technology Data Exchange (ETDEWEB)

    Beal, M.; Hsu, D.; McAtee, R.E.; Weidner, J.R. [EG and G Idaho, Inc., Idaho Falls, ID (United States); Berg, L.; McCandless, F.P.; Waltari, S.; Peterson, C. [Montana State Univ., Bozeman, MT (United States). Dept. of Chemical Engineering

    1992-08-01

    This report is a literature review of waste solvents recycle/recovery methods and shows the results of solvent separations using membrane and distillation technologies. The experimental solvent recovery methods were conducted on solvent replacements for chlorinated solvents at Montana State University. The literature review covers waste solvents separation using distillation, membranes decantation, filtration, carbon adsorption, solvent extraction, and other vapor-phase separation techniques. The results of this study identify solvent distillation methods as the most common separation technique. The alternative separation methods typically supplement distillation. The study shows the need for industries to identify waste solvent disposal methods and investigate the economics of waste solvent recycling as a possible waste reduction method.

  1. Solvent/non-solvent sintering: a novel route to create porous microsphere scaffolds for tissue regeneration.

    Science.gov (United States)

    Brown, Justin L; Nair, Lakshmi S; Laurencin, Cato T

    2008-08-01

    Solvent/non-solvent sintering creates porous polymeric microsphere scaffolds suitable for tissue engineering purposes with control over the resulting porosity, average pore diameter, and mechanical properties. Five different biodegradable biocompatible polyphosphazenes exhibiting glass transition temperatures from -8 to 41 degrees C and poly (lactide-co-glycolide), (PLAGA) a degradable polymer used in a number of biomedical settings, were examined to study the versatility of the process and benchmark the process to heat sintering. Parameters such as: solvent/non-solvent sintering solution composition and submersion time effect the sintering process. PLAGA microsphere scaffolds fabricated with solvent/non-solvent sintering exhibited an interconnected porosity and pore size of 31.9% and 179.1 mum, respectively which was analogous to that of conventional heat sintered PLAGA microsphere scaffolds. Biodegradable polyphosphazene microsphere scaffolds exhibited a maximum interconnected porosity of 37.6% and a maximum compressive modulus of 94.3 MPa. Solvent/non-solvent sintering is an effective strategy for sintering polymeric microspheres, with a broad spectrum of glass transition temperatures, under ambient conditions making it an excellent fabrication route for developing tissue engineering scaffolds and drug delivery vehicles. (c) 2007 Wiley Periodicals, Inc.

  2. Tracking Solvent Uptake in Block Polymer Thin Films during Solvent Vapor Annealing

    Science.gov (United States)

    Shelton, Cameron; Jones, Ronald; Dura, Joseph; Epps, Thomas

    2015-03-01

    A key goal in the block polymer (BP) thin films community is the design of a template-free, universal annealing method to control nanoscale self-assembly over large length scales. Solvent vapor annealing (SVA) offers a unique solution to this challenge with its ability to tune substrate surface, free surface, and polymer-polymer interactions by exposing films to appropriate solvents. However, there is little understanding of how the solvent behaves during the SVA process. In this work, we utilized the combination of deuterated solvents with small-angle neutron scattering (SANS) and neutron reflectometry to track solvent uptake in poly(styrene-b-isoprene-b-styrene) thin films. Two solvents were chosen for this analysis: d-hexane (isoprene selective) and d-benzene (styrene selective). Our work has shown that solvent choice and partial pressure have a significant impact on how solvent segregates within individual polymer domains and the film as a whole, directly impacting the restructuring of polymer domains. This work provides further understanding of the mechanism behind SVA, thereby making it easier to select appropriate conditions for desired self-assembly control.

  3. Assessment of solvents for cellulose dissolution.

    Science.gov (United States)

    Ghasemi, Mohammad; Tsianou, Marina; Alexandridis, Paschalis

    2017-03-01

    A necessary step in the processing of biomass is the pretreatment and dissolution of cellulose. A good solvent for cellulose involves high diffusivity, aggressiveness in decrystallization, and capability of disassociating the cellulose chains. However, it is not clear which of these factors and under what conditions should be improved in order to obtain a more effective solvent. To this end, a newly-developed phenomenological model has been applied to assess the controlling mechanism of cellulose dissolution. Among the findings, the cellulose fibers remain crystalline almost to the end of the dissolution process for decrystallization-controlled kinetics. In such solvents, decreasing the fiber crystallinity, e.g., via pretreatment, would result in a considerable increase in the dissolution rate. Such insights improve the understanding of cellulose dissolution and facilitate the selection of more efficient solvents and processing conditions for biomass. Specific examples of solvents are provided where dissolution is limited due to decrystallization or disentanglement. Copyright © 2016 Elsevier Ltd. All rights reserved.

  4. Ions, solutes and solvents, oh my!

    Energy Technology Data Exchange (ETDEWEB)

    Kemp, Daniel David [Iowa State Univ., Ames, IA (United States)

    2009-08-01

    Modern methods in ab initio quantum mechanics have become efficient and accurate enough to study many gas-phase systems. However, chemists often work in the solution phase. The presence of solvent molecules has been shown to affect reaction mechanisms1, lower reaction energy barriers2, participate in energy transfer with the solute3 and change the physical properties of the solute4. These effects would be overlooked in simple gas phase calculations. Careful study of specific solvents and solutes must be done in order to fully understand the chemistry of the solution phase. Water is a key solvent in chemical and biological applications. The properties of an individual water molecule (a monomer) and the behavior of thousands of molecules (bulk solution) are well known for many solvents. Much is also understood about aqueous microsolvation (small clusters containing ten water molecules or fewer) and the solvation characteristics when bulk water is chosen to solvate a solute. However, much less is known about how these properties behave as the cluster size transitions from the microsolvated cluster size to the bulk. This thesis will focus on species solvated with water clusters that are large enough to exhibit the properties of the bulk but small enough to consist of fewer than one hundred solvent molecules. New methods to study such systems will also be presented.

  5. Critical assessment and optimization of phase diagrams and thermodynamic properties of RE–Zn systems – Part II – Y–Zn, Eu–Zn, Gd–Zn, Tb–Zn, Dy–Zn, Ho–Zn, Er–Zn, Tm–Zn, Yb–Zn and Lu–Zn

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Zhijun; Pelton, Arthur D.

    2015-08-25

    Highlights: • All phase diagram and thermodynamic data critically assessed for 7 (10) binary systems. • All phases described by optimized thermodynamic models. • All systems assessed simultaneously thereby exploiting trends in rare earth series. • Results will be combined with RE–Zn, Mg–Zn and ternary optimizations. • Final product will be a database for multicomponent Mg–RE–Zn systems. - Abstract: All available phase diagram and thermodynamic data for the Y–Zn, Eu–Zn, Gd–Zn, Tb–Zn, Dy–Zn, Ho–Zn, Er–Zn, Tm–Zn, Yb–Zn and Lu–Zn systems have been collected and critically assessed. Optimized model parameters for the thermodynamic properties of all phases have been obtained. Trends in the properties of the rare earth (RE)–Zn systems as one traverses the rare earth series have been exploited for purposes of estimating missing data and for checking existing data for consistency.

  6. Recommended methods for purification of solvents and tests for impurities

    CERN Document Server

    Coetzee, J F

    1982-01-01

    Recommended Methods for Purification of Solvents and Tests for Impurities is a compilation of recommended procedures for purification of solvents and tests for solvent impurities. Ten solvents are covered: acetonitrile, sulfolane, propylene carbonate, dimethyl sulfoxide, dimethylformamide, hexamethylphosphoramide, pyridine, ethylenediamine, N-methylacetamide, and N-methylpropionamide. This book is comprised of 12 chapters and opens with an introduction to general aspects of impurity effects. The rationale for the selection of solvent is explained, and the relative reactivities of solutes in di

  7. Solvent engineering for high-quality perovskite solar cell with an efficiency approaching 20%

    Science.gov (United States)

    Wu, Tongyue; Wu, Jihuai; Tu, Yongguang; He, Xin; Lan, Zhang; Huang, Miaoliang; Lin, Jianming

    2017-10-01

    The perovskite layer is the most crucial factor for the high performance perovskite solar cells. Based on solvent engineering, we develop a ternary-mixed-solvent method for the growth of high-quality [Cs0.05(MA0.17FA0.83)0.95Pb(I0.83Br0.17)3] cation-anion-mixed perovskite films by introducing N-methyl-2-pyrrolidone (NMP) into the precursor mixed solution. By controlling rapid nucleation and retarding crystal growth via intermediate phase PbI2-NMP (Lewis acid-base adduct), a dense, large grain, pinhole-free and long charge carrier lifetime perovskite film is obtained. By optimizing the precursor solvent composition, the perovskite solar cell achieves an impressive power conversion efficiency of 19.61% under one-sun illumination. The research presented here provides a facile, low-cost and highly efficient way for the preparation of perovskite solar cells.

  8. Critical Proximity

    Directory of Open Access Journals (Sweden)

    Jane Simon

    2010-09-01

    Full Text Available This essay considers how written language frames visual objects. Drawing on Michel Foucault’s response to Raymond Roussel’s obsessive description, the essay proposes a model of criticism where description might press up against its objects. This critical closeness is then mapped across the conceptual art practice and art criticism of Ian Burn. Burn attends to the differences between seeing and reading, and considers the conditions which frame how we look at images, including how we look at, and through words. The essay goes on to consider Meaghan Morris’s writing on Lynn Silverman’s photographs. Both Morris and Burn offer an alternative to a parasitic model of criticism and enact a patient way of looking across and through visual landscapes.

  9. Critical proximity

    Directory of Open Access Journals (Sweden)

    Simon, Jane

    2010-01-01

    Full Text Available This essay considers how written language frames visual objects. Drawing on Michel Foucault’s response to Raymond Roussel’s obsessive description, the essay proposes a model of criticism where description might press up against its objects. This critical closeness is then mapped across the conceptual art practice and art criticism of Ian Burn. Burn attends to the differences between seeing and reading, and considers the conditions which frame how we look at images, including how we look at, and through words. The essay goes on to consider Meaghan Morris’s writing on Lynn Silverman’s photographs. Both Morris and Burn offer an alternative to a parasitic model of criticism and enact a patient way of looking across and through visual landscapes.

  10. Hazardous Solvent Substitution Data System tutorial

    Energy Technology Data Exchange (ETDEWEB)

    Twitchell, K.E.; Skinner, N.L.

    1993-07-01

    This manual is the tutorial for the Hazardous Solvent Substitution Data System (HSSDS), an online, comprehensive system of information on alternatives to hazardous solvents and related subjects. The HSSDS data base contains product information, material safety data sheets, toxicity reports, usage reports, biodegradable data, product chemical element lists, and background information on solvents. HSSDS use TOPIC{reg_sign} to search for information based on a query defined by the user. TOPIC provides a full text retrieval of unstructured source documents. In this tutorial, a series of lessons is provided that guides the user through basic steps common to most queries performed with HSSDS. Instructions are provided for both window-based and character-based applications.

  11. [Remaining solvents in dry cleaned over clothes].

    Science.gov (United States)

    Tashiro, H; Fujishiro, K; Matsuno, K; Kawamoto, T; Okubo, T

    1999-03-01

    We examined remaining solvents in dry cleaned trousers to estimate the magnitude of environmental pollution. A cleaning solvent of petroleum hydrocarbon was analyzed by means of capillary column mass spectrum gas chromatography. Principal ingredients were identified to be nonane, decane and undecane. The same main components were detected in dry cleaned trousers. Total amounts of evaporated vapor from a pair of trousers (480 g) in 5 days after dry cleaning were nonane (0.73 mg), decane (1.53 mg) and undecane (1.09 mg). The levels on the fifth day were 5%(nonane), 18%(decane) and 32%(undecane) of the first day's concentration, respectively. The half times of the remaining solvents were 1.0 day (nonane), 1.7 days (decane) and 2.7 days (undecane), respectively.

  12. Alternative Solvents through Green Chemistry Project

    Science.gov (United States)

    Hintze, Paul E.; Quinn, Jacqueline

    2014-01-01

    Components in the aerospace industry must perform with accuracy and precision under extreme conditions, and surface contamination can be detrimental to the desired performance, especially in cases when the components come into contact with strong oxidizers such as liquid oxygen. Therefore, precision cleaning is an important part of a components preparation prior to utilization in aerospace applications. Current cleaning technologies employ a variety of cleaning agents, many of which are halogenated solvents that are either toxic or cause environmental damage. Thus, this project seeks to identify alternative precision cleaning solvents and technologies, including use of less harmful cleaning solvents, ultrasonic and megasonic agitation, low-pressure plasma cleaning techniques, and supercritical carbon dioxide extraction. Please review all data content found in the Public Data tab located at: https:techport.nasa.govview11697public

  13. Changing the Mechanism for CO2 Hydrogenation Using Solvent-Dependent Thermodynamics.

    Science.gov (United States)

    Burgess, Samantha A; Appel, Aaron M; Linehan, John C; Wiedner, Eric S

    2017-11-20

    A critical scientific challenge for utilization of CO2 is the development of catalyst systems that function in water and use inexpensive and environmentally friendly reagents. We have used thermodynamic insights to predict and demonstrate that the HCoI (dmpe)2 catalyst system, previously described for use in organic solvents, can hydrogenate CO2 to formate in water with bicarbonate as the only added reagent. Replacing tetrahydrofuran as the solvent with water changes the mechanism for catalysis by altering the thermodynamics for hydride transfer to CO2 from a key dihydride intermediate. The need for a strong organic base was eliminated by performing catalysis in water owing to the change in mechanism. These studies demonstrate that the solvent plays a pivotal role in determining the reaction thermodynamics and thereby catalytic mechanism and activity. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Improvement of Soybean Oil Solvent Extraction through Enzymatic Pretreatment

    Directory of Open Access Journals (Sweden)

    F. V. Grasso

    2012-01-01

    Full Text Available The purpose of this study is to evaluate multienzyme hydrolysis as a pretreatment option to improve soybean oil solvent extraction and its eventual adaptation to conventional processes. Enzymatic action causes the degradation of the cell structures that contain oil. Improvements in terms of extraction, yield, and extraction rate are expected to be achieved. Soybean flakes and collets were used as materials and hexane was used as a solvent. Temperature, pH, and incubation time were optimized and diffusion coefficients were estimated for each solid. Extractions were carried out in a column, oil content was determined according to time, and a mathematical model was developed to describe the system. The optimum conditions obtained were pH 5.4, 38°C, and 9.7 h, and pH 5.8, 44°C, and 5.8h of treatment for flakes and collets, respectively. Hydrolyzed solids exhibited a higher yield. Diffusion coefficients were estimated between 10-11 and 10-10. The highest diffusion coefficient was obtained for hydrolyzed collets. 0.73 g oil/mL and 0.7 g oil/mL were obtained at 240 s in a column for collets and flakes, respectively. Hydrolyzed solids exhibited a higher yield. The enzymatic incubation accelerates the extraction rate and allows for higher yield. The proposed model proved to be appropriate.

  15. Highly Efficient Enzymatic Preparation of Daidzein in Deep Eutectic Solvents

    Directory of Open Access Journals (Sweden)

    Qi-Bin Cheng

    2017-01-01

    Full Text Available Daidzein, which is scarce in nature, has gained significant attention due to its superior biological activity and bioavailability compared with daidzin. So far, it has been widely used in the medicine and health care products industries. The enzymatic approach for the preparation of daidzein has prevailed, benefitted by its high efficiency and eco-friendly nature. Our present research aimed at providing a preparation method of daidzein by enzymatic hydrolysis of daidzin in a new “green” reaction medium-deep eutectic solvents (DESs. Herein, the DESs were screened via evaluating enzyme activity, enzyme stability and the substrate solubility, and the DES (ChCl/EG 2:1, 30 vol % was believed to be the most appropriate co-solvent to improve the bioconversion efficiency. Based on the yield of daidzein, response surface methodology (RSM was employed to model and optimize the reaction parameters. Under these optimum process conditions, the maximum yield of 97.53% was achieved and the purity of daidzein crude product reached more than 70%, which is more efficient than conversions in DESs-free buffer. Importantly, it has been shown that DESs medium could be reused for six batches of the process with a final conversion of above 50%. The results indicated that this procedure could be considered a mild, environmentally friendly, highly efficient approach to the economical production of daidzein, with a simple operation process and without any harmful reagents being involved.

  16. Impact of the solvent capacity constraint on E. coli metabolism

    Directory of Open Access Journals (Sweden)

    Barabási Albert-László

    2008-01-01

    Full Text Available Abstract Background Obtaining quantitative predictions for cellular metabolic activities requires the identification and modeling of the physicochemical constraints that are relevant at physiological growth conditions. Molecular crowding in a cell's cytoplasm is one such potential constraint, as it limits the solvent capacity available to metabolic enzymes. Results Using a recently introduced flux balance modeling framework (FBAwMC here we demonstrate that this constraint determines a metabolic switch in E. coli cells when they are shifted from low to high growth rates. The switch is characterized by a change in effective optimization strategy, the excretion of acetate at high growth rates, and a global reorganization of E. coli metabolic fluxes, the latter being partially confirmed by flux measurements of central metabolic reactions. Conclusion These results implicate the solvent capacity as an important physiological constraint acting on E. coli cells operating at high metabolic rates and for the activation of a metabolic switch when they are shifted from low to high growth rates. The relevance of this constraint in the context of both the aerobic ethanol excretion seen in fast growing yeast cells (Crabtree effect and the aerobic glycolysis observed in rapidly dividing cancer cells (Warburg effect should be addressed in the future.

  17. Green extraction of glycosides from Stevia rebaudiana (Bert. with low solvent consumption: A desirability approach

    Directory of Open Access Journals (Sweden)

    Paula M. Martins

    2016-12-01

    Full Text Available The sweet flavor of Stevia rebaudiana (Bert. leaf extract is well known and has raised the interest of huge food companies due to its natural bid. The extraction of their main glycosides stevioside and rebaudioside A is an important step on the preparation of final Stevia granules. The aim of the work reported here was to study and optimize the dynamic maceration of Stevia leaves using water and ethanol as green solvents. For instance, a fractional factorial design was chosen to evaluate the individual effects of the drug powder size, weight ratio of drug to solvent, temperature, agitation, and time on the yield of these glycosides. The glycosides were quantified by high pressure liquid chromatography. An exhaustive extraction by successive maceration steps showed that ethanol 70% was superior to water and ethanol 90% for stevioside and rebaudioside extraction. The liquid extract composition in dry basis and the yield of stevioside and rebaudioside A were significantly affected by the drug to solvent weight ratio, showing that larger volumes of solvent should be used. Furthermore, increasing solvent volume favors the extraction of the stevioside by a twofold factor as compared to rebaudioside A. Among the other factors, only drug powder size affected the yield of rebaudioside A significantly. The optimal solution for S. rebaudiana leaves dynamic extraction estimated by desirability functions methodology led to a condition which allows obtaining extraction yields of 2.31 and 1.24% for stevioside and rebaudioside A and their concentrations in dried extract corresponding to 8.38 and 4.51%, respectively. These high yields were obtained with drug to solvent ratio (1:10, w/w much higher than previous works, thus resulting in a more sustainable and green process.

  18. Solvent-resistant microporous polymide membranes

    Science.gov (United States)

    Miller, Warren K.; McCray, Scott B.; Friesen, Dwayne T.

    1998-01-01

    An asymmetric microporous membrane with exceptional solvent resistance and highly desirable permeability is disclosed. The membrane is made by a solution-casting or solution-spinning process from a copolyamic acid comprising the condensation reaction product in a solvent of at least three reactants selected from certain diamines and dianhydrides and post-treated to imidize and in some cases cross-link the copolyamic acid. The membrane is useful as an uncoated membrane for ultrafiltration, microfiltration, and membrane contactor applications, or may be used as a support for a permselective coating to form a composite membrane useful in gas separations, reverse osmosis, nanofiltration, pervaporation, or vapor permeation.

  19. Solvent-free fluidic organic dye lasers.

    Science.gov (United States)

    Choi, Eun Young; Mager, Loic; Cham, Tran Thi; Dorkenoo, Kokou D; Fort, Alain; Wu, Jeong Weon; Barsella, Alberto; Ribierre, Jean-Charles

    2013-05-06

    We report on the demonstration of liquid organic dye lasers based on 9-(2-ethylhexyl)carbazole (EHCz), so-called liquid carbazole, doped with green- and red-emitting laser dyes. Both waveguide and Fabry-Perot type microcavity fluidic organic dye lasers were prepared by capillary action under solvent-free conditions. Cascade Förster-type energy transfer processes from liquid carbazole to laser dyes were employed to achieve color-variable amplified spontaneous emission and lasing. Overall, this study provides the first step towards the development of solvent-free fluidic organic semiconducting lasers and demonstrates a new kind of optoelectronic applications for liquid organic semiconductors.

  20. NMR spectroscopy using liquid crystal solvents

    CERN Document Server

    Emsley, JW

    2013-01-01

    NMR Spectroscopy using Liquid Crystal Solvents covers the importance of using a liquid crystal solvent in NMR to derive nuclear dipolar spin-spin coupling constants. This book is composed of ten chapters, and begins with a brief description of the features and benefits of liquid crystal in NMR spectroscopic analysis. The succeeding chapters deal with the mode of operation of nuclear spin Hamiltonian for partially oriented molecules and the analysis of NMR spectra of partially oriented molecules, as well as the determination of rigid molecule structure. These topics are followed by discussions

  1. Kinetics of solvent-swelling of coal

    Energy Technology Data Exchange (ETDEWEB)

    Moreno, G.; Rincon, J.M.; Mora, E. [Lab. de Combustibles, Univ. Nacional de Colombia, Santafe de Bogota (Colombia); Klose, W. [GF Thermodynamik, Kassel Univ. (Germany)

    1997-12-31

    The kinetics of coal swelling by solvent of different basic strength is followed; Cerrejon and Yerbabuena (Colombian coals), Sacer-Endsdorf and Ruhr-Anna (Germany coals) were swollen with tetrahydrofuran, pyridine and butylamine. It was found that the swelling index decreases both with solvent basicity and coal rank. When the coal rank increases, the rates of swelling are: Initially, THF follows Fickian diffusion then follows anomalous case near case II; pyridine follows anomalous case near Fickian diffusion, whereas rate with butylamine initially is anomalous case of transport to Fickian diffusion. (orig.)

  2. Solvent dependence of cyanoindole fluorescence lifetime

    Science.gov (United States)

    Hilaire, Mary Rose; Mukherjee, Debopreeti; Troxler, Thomas; Gai, Feng

    2017-10-01

    Several cyanotryptophans have been shown to be useful biological fluorophores. However, how their fluorescence lifetimes vary with solvent has not been examined. In this regard, herein we measure the fluorescence decay kinetics as well as the absorption and emission spectra of six cyanoindoles in different solvents. In particular, we find, among other results, that only 4-cyanoindole affords a long fluorescence lifetime and hence high quantum yield in H2O. Therefore, our measurements provide not only a guide for choosing which cyanotryptophan to use in practice but also data for computational modeling of the substitution effect on the electronic transitions of indole.

  3. Brownian motion of a nano-colloidal particle: the role of the solvent.

    Science.gov (United States)

    Torres-Carbajal, Alexis; Herrera-Velarde, Salvador; Castañeda-Priego, Ramón

    2015-07-15

    Brownian motion is a feature of colloidal particles immersed in a liquid-like environment. Usually, it can be described by means of the generalised Langevin equation (GLE) within the framework of the Mori theory. In principle, all quantities that appear in the GLE can be calculated from the molecular information of the whole system, i.e., colloids and solvent molecules. In this work, by means of extensive Molecular Dynamics simulations, we study the effects of the microscopic details and the thermodynamic state of the solvent on the movement of a single nano-colloid. In particular, we consider a two-dimensional model system in which the mass and size of the colloid are two and one orders of magnitude, respectively, larger than the ones associated with the solvent molecules. The latter ones interact via a Lennard-Jones-type potential to tune the nature of the solvent, i.e., it can be either repulsive or attractive. We choose the linear momentum of the Brownian particle as the observable of interest in order to fully describe the Brownian motion within the Mori framework. We particularly focus on the colloid diffusion at different solvent densities and two temperature regimes: high and low (near the critical point) temperatures. To reach our goal, we have rewritten the GLE as a second kind Volterra integral in order to compute the memory kernel in real space. With this kernel, we evaluate the momentum-fluctuating force correlation function, which is of particular relevance since it allows us to establish when the stationarity condition has been reached. Our findings show that even at high temperatures, the details of the attractive interaction potential among solvent molecules induce important changes in the colloid dynamics. Additionally, near the critical point, the dynamical scenario becomes more complex; all the correlation functions decay slowly in an extended time window, however, the memory kernel seems to be only a function of the solvent density. Thus, the

  4. Vulnerability of critical infrastructures : identifying critical nodes.

    Energy Technology Data Exchange (ETDEWEB)

    Cox, Roger Gary; Robinson, David Gerald

    2004-06-01

    The objective of this research was the development of tools and techniques for the identification of critical nodes within critical infrastructures. These are nodes that, if disrupted through natural events or terrorist action, would cause the most widespread, immediate damage. This research focuses on one particular element of the national infrastructure: the bulk power system. Through the identification of critical elements and the quantification of the consequences of their failure, site-specific vulnerability analyses can be focused at those locations where additional security measures could be effectively implemented. In particular, with appropriate sizing and placement within the grid, distributed generation in the form of regional power parks may reduce or even prevent the impact of widespread network power outages. Even without additional security measures, increased awareness of sensitive power grid locations can provide a basis for more effective national, state and local emergency planning. A number of methods for identifying critical nodes were investigated: small-world (or network theory), polyhedral dynamics, and an artificial intelligence-based search method - particle swarm optimization. PSO was found to be the only viable approach and was applied to a variety of industry accepted test networks to validate the ability of the approach to identify sets of critical nodes. The approach was coded in a software package called Buzzard and integrated with a traditional power flow code. A number of industry accepted test networks were employed to validate the approach. The techniques (and software) are not unique to power grid network, but could be applied to a variety of complex, interacting infrastructures.

  5. Mitigation of solvent interference using a short packed column prior to ion mobility spectrometry.

    Science.gov (United States)

    Jafari, Mohammad T; Saraji, Mohammad; Mossaddegh, Mehdi

    2017-05-15

    This paper introduces a novel approach to overcome the solvent interference in corona discharge-ion mobility spectrometry (CD-IMS) based on the time-resolved signals of the solvent and the analyte. To that end, a short Teflon tube was filled with a low amount of squalene or OV-1, which was prepared and located between the injection port and the entrance of the CD-IMS cell. Through this procedure, a sufficient delay (~5s) was obtained between the introduction of the solvent and the analyte into the reaction region of IMS. This resulted in removing the proton by solvent molecules, as well as increasing the effective collision during the analyte ionization, thereby providing an analysis with more sensitivity, accuracy, and precision. To show the column efficiency, ethion and diazinon (organophosphorus pesticides) were selected as the test compounds and their solutions were analyzed by the proposed method. The amount of sorbent, carrier gas flow rate, and the sorbent temperature affecting the sorbent efficiency were optimized by employing the response surface methodology and the central composite design. The proposed method was exhaustively validated in terms of sensitivity, linearity, and repeatability. In particular, the feasibility of direct injection was successfully verified by the satisfactory results, as compared with those achieved without the prior column. The methodology used in this study is very simple and inexpensive, which can overcome the solvent interference when a solution is directly injected into the CD-IMS. Copyright © 2017 Elsevier B.V. All rights reserved.

  6. Morin-based nanofiltration membranes for organic solvent separation processes

    KAUST Repository

    Perez Manriquez, Liliana

    2018-02-26

    In this work we demonstrate the successful optimization of the interfacial polymerization reaction for the manufacture of organic solvent nanofiltration membranes by replacing the toxic amines commonly used for this method with the natural occurring bio-polyphenol morin. For the manufacture of this type of OSN membrane a crosslinked PAN support was coated by interfacial polymerization using morin as the monomer of the aqueous phase and terephtaloyl chloride as the monomer of the organic phase. These membranes showed an exceptional performance and resistance to NMP by having a a permeance of 0.3L/m2 h bar in NMP with a rejection of 96% of Brilliant Blue dye which has a molecular weight of 825.97g/mol, making these membranes attractive for harsh industrial separation processes due to their ease of manufacture, low cost, and excellent performance.

  7. Global transcriptional response of solvent-sensitive and solvent-tolerant Pseudomonas putida strains exposed to toluene.

    Science.gov (United States)

    Molina-Santiago, Carlos; Udaondo, Zulema; Gómez-Lozano, María; Molin, Soren; Ramos, Juan-Luis

    2017-02-01

    Pseudomonas putida strains are generally recognized as solvent tolerant, exhibiting varied sensitivity to organic solvents. Pan-genome analysis has revealed that 30% of genes belong to the core-genome of Pseudomonas. Accessory and unique genes confer high degree of adaptability and capabilities for the degradation and synthesis of a wide range of chemicals. For the use of these microbes in bioremediation and biocatalysis, it is critical to understand the mechanisms underlying these phenotypic differences. In this study, RNA-seq analysis compared the short- and long-term responses of the toluene-sensitive KT2440 strain and the highly tolerant DOT-T1E strain. The sensitive strain activates a larger number of genes in a higher magnitude than DOT-T1E. This is expected because KT2440 bears one toluene tolerant pump, while DOT-T1E encodes three of these pumps. Both strains activate membrane modifications to reduce toluene membrane permeability. The KT2440 strain activates the TCA cycle to generate energy, while avoiding energy-intensive processes such as flagellar biosynthesis. This suggests that KT2440 responds to toluene by focusing on survival mechanisms. The DOT-T1E strain activates toluene degradation pathways, using toluene as source of energy. Among the unique genes encoded by DOT-T1E is a 70 kb island composed of genes of unknown function induced in response to toluene. © 2016 Society for Applied Microbiology and John Wiley & Sons Ltd.

  8. Controlling Actinide Hydration in Mixed Solvent Systems: Towards Tunable Solvent Systems to Close the Fuel Cycle

    Energy Technology Data Exchange (ETDEWEB)

    Clark, Sue B. [Washington State Univ., Pullman, WA (United States). Dept. of Chemistry

    2016-10-31

    The goal of this project has been to define the extent of hydration the f-elements and other cations in mixed solvent electrolyte systems. Methanol-water and other mixed solvent systems have been studied, where the solvent dielectric constant was varied systematically. Thermodynamic and spectroscopic studies provide details concerning the energetics of complexation and other reactions of these cations. This information has also been used to advance new understanding of the behavior of these cations in a variety of systems, ranging from environmental studies, chromatographic approaches, and ionization processes for mass spectrometry.

  9. Refinement of protein structures in explicit solvent

    NARCIS (Netherlands)

    Linge, J.P.; Williams, M.A.; Spronk, C.A.E.M.; Bonvin, A.M.J.J.|info:eu-repo/dai/nl/113691238; Nilges, M.

    2003-01-01

    We present a CPU efficient protocol for refinement of protein structures in a thin layer of explicit solvent and energy parameters with completely revised dihedral angle terms. Our approach is suitable for protein structures determined by theoretical (e.g., homology modeling or threading) or

  10. Deposition dynamics of multi-solvent bioinks

    Science.gov (United States)

    Kaneelil, Paul; Pack, Min; Cui, Chunxiao; Han, Li-Hsin; Sun, Ying

    2017-11-01

    Inkjet printing cellular scaffolds using bioinks is gaining popularity due to the advancement of printing technology as well as the growing demands of regenerative medicine. Numerous studies have been conducted on printing scaffolds of biomimetic structures that support the cell production of human tissues. However, the underlying physics of the deposition dynamics of bioinks remains elusive. Of particular interest is the unclear deposition dynamics of multi-solvent bioinks, which is often used to tune the micro-architecture formation. Here we systematically studied the effects of jetting frequency, solvent properties, substrate wettability, and temperature on the three-dimensional deposition patterns of bioinks made of Methacrylated Gelatin and Carboxylated Gelatin. The microflows inside the inkjet-printed picolitre drops were visualized using fluorescence tracer particles to decipher the complex processes of multi-solvent evaporation and solute self-assembly. The evolution of droplet shape was observed using interferometry. With the integrated techniques, the interplay of solvent evaporation, biopolymer deposition, and multi-drop interactions were directly observed for various ink and substrate properties, and printing conditions. Such knowledge enables the design and fabrication of a variety of tissue engineering scaffolds for potential use in regenerative medicine.

  11. Solvent-tolerant bacteria in biocatalysis.

    NARCIS (Netherlands)

    Bont, de J.A.M.

    1998-01-01

    The toxicity of fine chemicals to the producer organism is a problem in several biotechnological production processes. In several instances, an organic phase can be used to extract the toxic product from the aqueous phase during a fermentation. With the discovery of solvent-tolerant bacteria, more

  12. Solvent (acetone-butanol: ab) production

    Science.gov (United States)

    This article describes production of butanol [acetone-butanol-ethanol, (also called AB or ABE or solvent)] by fermentation using both traditional and current technologies. AB production from agricultural commodities, such as corn and molasses, was an important historical fermentation. Unfortunately,...

  13. Mixed Solvent Reactive Recrystallization of Sodium Carbonate

    NARCIS (Netherlands)

    Gaertner, R.S.

    2005-01-01

    Investigation of the reactive recrystallization of trona (sodium sesquicarbonate) and sodium bicarbonate to sodium carbonate (soda) in a mixed solvent led to the design of several alternative, less energy consumptive, economically very attractive process routes for the production of soda from all

  14. Solvent-Free Synthesis of Chalcones

    Science.gov (United States)

    Palleros, Daniel R.

    2004-01-01

    The synthesis of twenty different chalcones in the absence of solvent is presented. The results indicated that out of the twenty different chalcones investigated seventeen can be obtained in a matter of minutes by mixing the corresponding benzaldehyde and acetophenone in the presence of solid NaOH in a mortar with pestle.

  15. Binary-solvent-based ionic-liquid-assisted surfactant-enhanced emulsification microextraction for the determination of four fungicides in apple juice and apple vinegar.

    Science.gov (United States)

    Chen, Xiaochu; Zhang, Xu; Liu, Fengmao; Hou, Fan

    2017-02-01

    A binary-solvent-based ionic-liquid-assisted surfactant-enhanced emulsification microextraction method was developed for the separation/preconcentration and determination of four fungicides (pyrimethanil, fludioxonil, cyprodynil, pyraclostrobin) in apple juice and apple vinegar. A nonchlorinated solvent amyl acetate, which has a lower density than water, was used as the extraction solvent, and an ionic liquid 1-hexyl-3-methylimidazolium hexafluorophosphate, which has a high density and low toxicity, was used as a secondary solvent mixed with the extraction solvent. After centrifugation, the binary solvent drop with a relatively high density was deposited on the bottom of the tube. Some parameters influencing the extraction efficiency of analytes such as type of extraction solvent, ratio of ionic liquid, volume of mixed solvent, type and concentration of surfactant, sample pH, NaCl concentration, and vortex time were investigated and optimized. Under the optimized conditions, the proposed method provided a good linearity in the range of 5-200 μg/L. The limits of quantification of the method were in the range of 2-5 μg/L. The relative standard deviations for interday assays were 1.7-11.9%. The method was applied to the determination of pyrimethanil, fludioxonil, cyprodynil, and pyraclostrobin in apple juice and apple vinegar samples, and the accuracy was evaluated through recovery experiments. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Gas separation by composite solvent-swollen membranes

    Science.gov (United States)

    Matson, Stephen L.; Lee, Eric K. L.; Friesen, Dwayne T.; Kelly, Donald J.

    1989-01-01

    There is disclosed a composite immobulized liquid membrane of a solvent-swollen polymer and a microporous organic or inorganic support, the solvent being at least one highly polar solvent containing at least one nitrogen, oxygen, phosphorous or sulfur atom, and having a boiling point of at least 100.degree. C. and a specified solubility parameter. The solvent or solvent mixture is homogeneously distributed through the solvent-swollen polymer from 20% to 95% by weight. The membrane is suitable for acid gas scrubbing and oxygen/nitrogen separation.

  17. Critical Vidders

    DEFF Research Database (Denmark)

    Svegaard, Robin Sebastian Kaszmarczyk

    2015-01-01

    This article will introduce and take a look at a specific subset of the fan created remix videos known as vids, namely those that deal with feminist based critique of media. Through examples, it will show how fans construct and present their critique, and finally broach the topic of the critical ...

  18. Justification of the solvent choice for the industrial amizon substance production

    Directory of Open Access Journals (Sweden)

    V. A. Georgiyants

    2014-08-01

    solvents as the most similar in their properties and acceptable cost, we considered for possible use in industrial amizone production. In the first phase the solubility of the intermediate (Bink and amizone in these solvents were studied. It was found that substance was very slightly soluble in cold organic solvents and was easily soluble in boiling. Water adding to these solvents in various ratios significantly improved solubility, and the best solubility, as expected, had water. To justify the choice of solvents for the first and second stage of the synthesis and crystallization an experimental study of the efficacy of using ethanol, acetone and 2-propanol in various processes of synthesis was done. Thus the yield of final product was evaluated and the amount of associated impurities before and after crystallization was measured. It was proved that at the synthesis stage it is expedient to use 2-propanol and as crystallization solvent – ethanol. CONCLUSIONS 1. Experimental studies for the justification for the choice of solvent for the industrial synthesis of isonicotinic acid benzylamide iodomethylate substance considering QbD concepts and classes of toxic solvents were done. 2. It was established that in the synthesis is optimal to use 2-propanol and for crystallization - ethanol.

  19. GPU/CPU Algorithm for Generalized Born/Solvent-Accessible Surface Area Implicit Solvent Calculations

    OpenAIRE

    Tanner, David E.; Phillips, James C.; Schulten, Klaus

    2012-01-01

    Molecular dynamics methodologies comprise a vital research tool for structural biology. Molecular dynamics has benefited from technological advances in computing, such as multi-core CPUs and graphics processing units (GPUs), but harnessing the full power of hybrid GPU/CPU computers remains difficult. The generalized Born/solvent-accessible surface area implicit solvent model (GB/SA) stands to benefit from hybrid GPU/CPU computers, employing the GPU for the GB calculation and the CPU for the S...

  20. Biodiesel production from ethanolysis of palm oil using deep eutectic solvent (DES) as co-solvent

    Science.gov (United States)

    Manurung, R.; Winarta, A.; Taslim; Indra, L.

    2017-06-01

    Biodiesel produced from ethanolysis is more renewable and have better properties (higher oxidation stability, lower cloud and pour point) compared to methanolysis, but it has a disadvantage such as complicated purification. To improve ethanolysis process, deep eutectic solvent (DES) can be prepared from choline chloride and glycerol and used as co-solvent in ethanolysis. The deep eutectic solvent is formed from a quaternary ammonium salt (choline chloride) and a hydrogen bond donor (Glycerol), it is a non-toxic, biodegradable solvent compared to a conventional volatile organic solvent such as hexane. The deep eutectic solvent is prepared by mixing choline chloride and glycerol with molar ratio 1:2 at temperature 80 °C, stirring speed 300 rpm for 1 hour. The DES is characterized by its density and viscosity. The ethanolysis is performed at a reaction temperature of 70 °C, ethanol to oil molar ratio of 9:1, potassium hydroxide as catalyst concentration of 1.2 wt. DES as co-solvent with concentration 0.5 to 3 wt. stirring speed 400 rpm, and a reaction time 1 hour. The obtained biodiesel is then characterized by its density, viscosity, and ester content. The oil - ethanol phase condition is observed in the reaction tube. The oil - ethanol phase with DES tends to form meniscus compared to without DES, showed that oil and ethanol become more slightly miscible, which favors the reaction. Using DES as co-solvent in ethanolysis showed increasing in yield and easier purification. The esters properties meet the international standards ASTM D6751, with the highest yield achieved 83,67 with 99,77 conversion at DES concentration 2 . Increasing DES concentration above 2 in ethanolysis decrease the conversion and yield, because of the excessive glycerol in the systems makes the reaction equilibrium moves to the reactant side.

  1. Critical reading and critical thinking Critical reading and critical thinking

    Directory of Open Access Journals (Sweden)

    Loni Kreis Taglieber

    2008-04-01

    Full Text Available The purpose of this paper is to provide, for L1 and L2 reading and writing teachers, a brief overview of the literature about critical reading and higher level thinking skills. The teaching of these skills is still neglected in some language classes in Brazil, be it in L1 or in L2 classes. Thus, this paper may also serve as a resource guide for L1 and/or L2 reading and writing teachers who want to incorporate critical reading and thinking into their classes. In modern society, even in everyday life people frequently need to deal with complicated public and political issues, make decisions, and solve problems. In order to do this efficiently and effectively, citizens must be able to evaluate critically what they see, hear, and read. Also, with the huge amount of printed material available in all areas in this age of “information explosion” it is easy to feel overwhelmed. But often the information piled up on people’s desks and in their minds is of no use due to the enormous amount of it. The purpose of this paper is to provide, for L1 and L2 reading and writing teachers, a brief overview of the literature about critical reading and higher level thinking skills. The teaching of these skills is still neglected in some language classes in Brazil, be it in L1 or in L2 classes. Thus, this paper may also serve as a resource guide for L1 and/or L2 reading and writing teachers who want to incorporate critical reading and thinking into their classes. In modern society, even in everyday life people frequently need to deal with complicated public and political issues, make decisions, and solve problems. In order to do this efficiently and effectively, citizens must be able to evaluate critically what they see, hear, and read. Also, with the huge amount of printed material available in all areas in this age of “information explosion” it is easy to feel overwhelmed. But often the information piled up on people’s desks and in their minds is of

  2. STAR POLYMERS IN GOOD SOLVENTS FROM DILUTE TO CONCENTRATED REGIMES: CROSSOVER APPROACH

    Directory of Open Access Journals (Sweden)

    S.B.Kiselev

    2002-01-01

    Full Text Available An introduction is given to the crossover theory of the conformational and thermodynamic properties of star polymers in good solvents. The crossover theory is tested against Monte Carlo simulation data for the structure and thermodynamics of model star polymers. In good solvent conditions, star polymers approach a "universal" limit as N → ∞, however, there are two types of approach towards this limit. In the dilute regime, a critical degree of polymerization N* is found to play a similar role as the Ginzburg number in the crossover theory for critical phenomena in simple fluids. A rescaled penetration function is found to control the free energy of star polymer solutions in the dilute and semidilute regions. This equation of state captures the scaling behaviour of polymer solutions in the dilute/semidilute regimes and also performs well in the concentrated regimes, where the details of the monomer-monomer interactions become important.

  3. Relative ototoxicity of 21 aromatic solvents

    Energy Technology Data Exchange (ETDEWEB)

    Gagnaire, Francois; Langlais, Cristina [Institut National de Recherche et de Securite, Departement Polluants et Sante, Vandoeuvre (France)

    2005-06-01

    Some aromatic solvents (e.g. toluene, p-xylene, styrene, and ethylbenzene) show, in the rat, striking ototoxicity characterized by an irreversible hearing loss, as measured by behavioural or electrophysiological methods, associated with damage to outer hair cells in the cochlea of the exposed animals. To broaden the range of aromatic solvents studied concerning their potential ototoxicity and to compare their ototoxicity quantitatively, 21 aromatic solvents were administered orally by gastric intubation to Sprague-Dawley rats for 5 days/week for a 2-week period. The dose used was 8.47 mmol kg{sup -1} body weight day{sup -1}. The possible ototoxicity of the aromatic solvents was evaluated by morphological investigation of the cochlea. Whole-mount surface preparations of the organ of Corti were made to quantify the number of missing hair cells (cytocochleogram). Among the 21 solvents studied, eight (toluene, p-xylene, ethylbenzene, n-propylbenzene, styrene, {alpha}-methylstyrene, trans-{beta}-methylstyrene, and allylbenzene) caused histological lesions of the organ of Corti. They differed widely in their potency. The least ototoxic solvents caused outer hair cell (OHC) loss in the middle turn of the organ of Corti. The OHC loss was slight in the first row, and greater in the second and third rows. The most ototoxic solvents caused high losses in the three rows of the outer hair cells along the entire length of the basilar membrane. There were also occasional inner hair cell (ICH) losses in the most affected animals. Although no measurements were made of the chemical concentrations reached in the blood or the brain, tentative ranking of an increasing ototoxicity of the eight aromatic solvents could be proposed on the basis of the histological losses observed - {alpha}-methylstyrene

  4. Numerical Treatment of Stokes Solvent Flow and Solute-Solvent Interfacial Dynamics for Nonpolar Molecules.

    Science.gov (United States)

    Sun, Hui; Zhou, Shenggao; Moore, David K; Cheng, Li-Tien; Li, Bo

    2016-05-01

    We design and implement numerical methods for the incompressible Stokes solvent flow and solute-solvent interface motion for nonpolar molecules in aqueous solvent. The balance of viscous force, surface tension, and van der Waals type dispersive force leads to a traction boundary condition on the solute-solvent interface. To allow the change of solute volume, we design special numerical boundary conditions on the boundary of a computational domain through a consistency condition. We use a finite difference ghost fluid scheme to discretize the Stokes equation with such boundary conditions. The method is tested to have a second-order accuracy. We combine this ghost fluid method with the level-set method to simulate the motion of the solute-solvent interface that is governed by the solvent fluid velocity. Numerical examples show that our method can predict accurately the blow up time for a test example of curvature flow and reproduce the polymodal (e.g., dry and wet) states of hydration of some simple model molecular systems.

  5. Actualización de los límites críticos del intervalo hídrico óptimo Review of the critical limits of the optimal hydric interval

    Directory of Open Access Journals (Sweden)

    Miguel Angel PIlatti

    2012-07-01

    Full Text Available El Intervalo Hídrico Óptimo (IHO es la fracción de agua edáfica fácilmente utilizable por los cultivos, durante la cual el suelo puede ser penetrado por las raíces sin mayor resistencia y la aeración no limita la respiración radical. En este trabajo se discuten los límites superior e inferior del IHO. El primero es èCC -agua retenida en capacidad de campo- si garantiza una aceptable capacidad de aire (èa; de lo contrario, el límite se alcanza cuando èa no restringe la respiración radical. El límite inferior queda determinado por la variable de mayor valor entre èRP (contenido hídrico edáfico por debajo del cual las raíces restringen su crecimiento, y èFU (agua fácilmente utilizable por debajo del cual comienza el estrés hídrico. Se analiza y discute la validez de los límites, y las dificultades metodológicas que implican sus determinaciones. Se comparan valores del IHO obtenidos por otros autores, que utilizaron diferentes límites, con los calculados con los límites críticos aquí propuestos. Cada situación agronómica (combinación de suelos, clima, cultivo requiere valores particulares de IHO que deberán ser determinados para cada región. Para el norte de la Región Pampeana (Argentina y sus cultivos habituales proponemos los siguientes valores críticos: èCC = contenido hídrico a -10 kPa; èa = 15%; èRP = 2,5 a 6 MPa (según el porcentaje de arcilla y èFU = -0,17 MPa.The Optimal Hydric Interval (IHO is the interval of easily available soil water for the crops, during which soil resistance and aeration do not limit root growth. In this paper, the upper and lower limits of the IHO are discussed. The upper limit is èCC (soil water content at field capacity when air capacity (èa is not restrictive for root respiration; otherwise, the limit is èa. The lower limit is determined by the variable of greater value between èRP (soil water content at which soil resistance reduces root elongation and èFU (soil water

  6. Critical scattering

    Energy Technology Data Exchange (ETDEWEB)

    Stirling, W.G. [Liverpool Univ., Dep. of Physics, Liverpool (United Kingdom); Perry, S.C. [Keele Univ. (United Kingdom). Dept. of Physics

    1996-12-31

    We outline the theoretical and experimental background to neutron scattering studies of critical phenomena at magnetic and structural phase transitions. The displacive phase transition of SrTiO{sub 3} is discussed, along with examples from recent work on magnetic materials from the rare-earth (Ho, Dy) and actinide (NpAs, NpSb, USb) classes. The impact of synchrotron X-ray scattering is discussed in conclusion. (author) 13 figs., 18 refs.

  7. Occupational Exposure to Chlorinated and Petroleum Solvents and Mycosis Fungoides

    DEFF Research Database (Denmark)

    Morales-Suárez-Varela, Maria M; Olsen, Jorn; Villeneuve, Sara

    2013-01-01

    To evaluate the potential association between occupational exposure to chlorinated and petroleum solvents and mycosis fungoides (MF).......To evaluate the potential association between occupational exposure to chlorinated and petroleum solvents and mycosis fungoides (MF)....

  8. Method for Predicting Solubilities of Solids in Mixed Solvents

    DEFF Research Database (Denmark)

    Ellegaard, Martin Dela; Abildskov, Jens; O'Connell, J. P.

    2009-01-01

    A method is presented for predicting solubilities of solid solutes in mixed solvents, based on excess Henry's law constants. The basis is statistical mechanical fluctuation solution theory for composition derivatives of solute/solvent infinite dilution activity coefficients. Suitable approximations...

  9. The Ideal Solvent for Paper Chromatography of Food Dyes.

    Science.gov (United States)

    Markow, Peter G.

    1988-01-01

    Uses paper chromatography with food dyes to provide a simple and inexpensive basis for teaching chromatography. Provides experimental methodology and tabled results. Includes a solvent system comparison (Rf) for seven dyes and twenty-two solvents. (MVL)

  10. Organic Solvent Tropical Report [SEC 1 and 2

    Energy Technology Data Exchange (ETDEWEB)

    COWLEY, W.L.

    2000-06-21

    This report provides the basis for closing the organic solvent safety issue. Sufficient information is presented to conclude that risk posed by an unmitigated organic solvent fire is within risk evaluation guidelines.

  11. Non-Aqueous Biocatalysis in Homogeneous Solvent Systems

    Directory of Open Access Journals (Sweden)

    Sebastián Torres

    2004-01-01

    Full Text Available Enzymes are highly specific catalysts that typically function in aqueous solvents. However, many enzymes retain their catalytic activities at high concentrations in non- aqueous environments, including neat hydrophilic organic solvents. In fact, enzymes can be used to carry out reactions in organic solvents that are not possible in aqueous systems. Therefore, biocatalysis in homogenous non-aqueous solvents offers possibilities for producing useful chemicals and several synthetic reactions have already been developed using this type of system. The current review discusses factors that influence enzyme catalysis in non-aqueous solvents such us water content, solvent concentration, interaction of solvent with protein structure, stability and activity. Also, new strategies for non-conventional biocatalysis using extremophiles and ionic solvents are mentioned.

  12. Sensibilidade do carrapato Boophilus microplus a solventes Sensibility of Boophilus microplus tick to solvents

    Directory of Open Access Journals (Sweden)

    Ana Carolina de Souza Chagas

    2003-02-01

    Full Text Available Os experimentos envolvendo o uso de acaricidas sintéticos ou naturais, geralmente necessitam da utilização de um solvente. Com a finalidade de verificar a sensibilidade do carrapato bovino Boophilus microplus a diferentes solventes, larvas e fêmeas ingurgitadas deste ectoparasito foram expostas a sete solventes em cinco diferentes concentrações, na ausência e presença de azeite de oliva. Os resultados mostraram que a utilização do azeite de oliva não produz resultados diferentes estatisticamente em testes de larvas com papel impregnado, fato não verificado em testes de imersão de adultos com compostos hidrofílicos. A mortalidade média causada pelos solventes foi menor nos testes com papel impregnado, aumentando nos testes de imersão de larvas e de adultos. Solventes de baixo peso molecular e pouca viscosidade como o álcool metílico e o álcool etílico, não interferiram na mortalidade média em testes biológicos de B. microplus, principalmente em concentrações inferiores a 76%.Experiments carried out with synthetic or natural acaricides usually use a solvent. To investigate the sensitivity of Boophilus microplus cattle tick to different solvents, larvae and engorged female were subjected to seven solvents in five different concentrations. It was done in the presence and absence of olive oil. The results showed that the utilization of olive oil doesn't produce different statistical results in impregnated paper larvae test. It did not happen in adults immersion test with hydrophilic compounds. The mean mortality caused by solvents was small in impregnated paper larvae test, increasing in immersion tests of larvae and adults. Solvents with low molecular weight and viscosity like ethyl alcohol and methyl alcohol did not cause interference in the mortality of B. microplus in biological tests, mainly in concentrations below 76%.

  13. Preparation of Highly Pure Vanadyl Sulfate from Sulfate Solutions Containing Impurities of Iron and Aluminum by Solvent Extraction Using EHEHPA

    OpenAIRE

    Dan Li; Desheng Chen; Guozhi Zhang; Hongxin Zhao; Tao Qi; Weijing Wang; Lina Wang; Yahui Liu

    2017-01-01

    The preparation of highly pure vanadyl sulfate from sulfate solutions containing impurities of iron and aluminumwas investigated by solvent extraction with 2-ethylhexyl phosphoric acid mono-2-ethylhexyl ester (EHEHPA) and tri-n-butyl phosphate (TBP) as the phase modifier. The extraction and stripping conditions of vanadium (IV) and its separation from iron and aluminum were optimized. Under the optimal extraction conditions, the extraction of vanadium (IV) and iron were 68% and 53%, respectiv...

  14. Gamma Ray Radiolysis of the FPEX Solvent

    Energy Technology Data Exchange (ETDEWEB)

    B. J. Mincher; S. P. Mezyk; D. R. Peterman

    2006-09-01

    Slide presentation. FPEX contains a calixarene for Cs extraction, a crown ether for Sr extraction, Cs7SB modifier, and TOA to aid in stripping, in Isopar L diluent. The radiation stability FPEX must be evaluated prior to process use. Radiolytic degradation of species in solution are due to reaction with the direct radiolysis products of the diluent. In Isopar L, the reactive species produced include e-, •H and alkane radicals, resulting in a reducing environment. However, in nitric acid, oxidizing hydroxyl (•OH) and nitro (•NO2) radicals dominate system chemistry. Thus, the nature of diluent and the presence of radical scavengers affect the results of irradiation. We report the preliminary results of a new program to investigate the radiolysis of FPEX using the 60Co irradiation of FPEX neat solvent, acid pre-equilibrated solvent and mixed aerated phases. The Cs and Sr distribution ratios were used as metrics.

  15. High performance hydrophobic solvent, carbon dioxide capture

    Science.gov (United States)

    Nulwala, Hunaid; Luebke, David

    2017-05-09

    Methods and compositions useful, for example, for physical solvent carbon capture. A method comprising: contacting at least one first composition comprising carbon dioxide with at least one second composition to at least partially dissolve the carbon dioxide of the first composition in the second composition, wherein the second composition comprises at least one siloxane compound which is covalently modified with at least one non-siloxane group comprising at least one heteroatom. Polydimethylsiloxane (PDMS) materials and ethylene-glycol based materials have high carbon dioxide solubility but suffer from various problems. PDMS is hydrophobic but suffers from low selectivity. Ethylene-glycol based systems have good solubility and selectivity, but suffer from high affinity to water. Solvents were developed which keep the desired combinations of properties, and result in a simplified, overall process for carbon dioxide removal from a mixed gas stream.

  16. Myoglobin solvent structure at different temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Daniels, B.V.; Korszun, Z.R. [Brookhaven National Laboratory, Upton, NY (United States); Schoenborn, B.P. [Los Alamos National Laboratory, NM (United States)

    1994-12-31

    The structure of the solvent surrounding myoglobin crystals has been analyzed using neutron diffraction data, and the results indicate that the water around the protein is not disordered, but rather lies in well-defined hydration shells. We have analyzed the structure of the solvent surrounding the protein by collecting neutron diffraction data at four different temperatures, namely, 80, 130, 180, and 240K. Relative Wilson Statistics applied to low resolution data showed evidence of a phase transition in the region of 180K. A plot of the liquidity factor, B{sub sn}, versus distance from the protein surface begins with a high plateau near the surface of the protein and drops to two minima at distances from the protein surface of about 2.35{Angstrom} and 3.85{Angstrom}. Two distinct hydration shells are observed. Both hydration shells are observed to expand as the temperature is increased.

  17. 27 CFR 21.125 - Rubber hydrocarbon solvent.

    Science.gov (United States)

    2010-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 1 2010-04-01 2010-04-01 false Rubber hydrocarbon solvent. 21.125 Section 21.125 Alcohol, Tobacco Products and Firearms ALCOHOL AND TOBACCO TAX AND TRADE BUREAU....125 Rubber hydrocarbon solvent. (a) Rubber hydrocarbon solvent is a petroleum derivative. (b...

  18. Green solvents and technologies for oil extraction from oilseeds.

    Science.gov (United States)

    Kumar, S P Jeevan; Prasad, S Rajendra; Banerjee, Rintu; Agarwal, Dinesh K; Kulkarni, Kalyani S; Ramesh, K V

    2017-01-01

    Oilseeds are crucial for the nutritional security of the global population. The conventional technology used for oil extraction from oilseeds is by solvent extraction. In solvent extraction, n-hexane is used as a solvent for its attributes such as simple recovery, non-polar nature, low latent heat of vaporization (330 kJ/kg) and high selectivity to solvents. However, usage of hexane as a solvent has lead to several repercussions such as air pollution, toxicity and harmfulness that prompted to look for alternative options. To circumvent the problem, green solvents could be a promising approach to replace solvent extraction. In this review, green solvents and technology like aqueous assisted enzyme extraction are better solution for oil extraction from oilseeds. Enzyme mediated extraction is eco-friendly, can obtain higher yields, cost-effective and aids in obtaining co-products without any damage. Enzyme technology has great potential for oil extraction in oilseed industry. Similarly, green solvents such as terpenes and ionic liquids have tremendous solvent properties that enable to extract the oil in eco-friendly manner. These green solvents and technologies are considered green owing to the attributes of energy reduction, eco-friendliness, non-toxicity and non-harmfulness. Hence, the review is mainly focussed on the prospects and challenges of green solvents and technology as the best option to replace the conventional methods without compromising the quality of the extracted products.

  19. Organic Synthesis under Solvent-free Condition. An Environmentally ...

    Indian Academy of Sciences (India)

    environmental pollution caused by solvents and also their academic interest in solid-solid reactions have led them in recent times to develop methodologies for solvent-free reac- tions with considerable success. The Function of a Solvent. A general assumption with regard to organic reactions is that they are performed in a ...

  20. Catalytic coal liquefaction with treated solvent and SRC recycle

    Science.gov (United States)

    Garg, Diwakar; Givens, Edwin N.; Schweighardt, Frank K.

    1986-01-01

    A process for the solvent refining of coal to distillable, pentane soluble products using a dephenolated and denitrogenated recycle solvent and a recycled, pentane-insoluble, solvent-refined coal material, which process provides enhanced oil-make in the conversion of coal.

  1. Solvent density mode instability in non-polar solutions

    Indian Academy of Sciences (India)

    Abstract. We analyse the origin of the multiple long time scales associated with the long time decay observed in non-polar solvation dynamics by linear stability analysis of solvent density modes where the effects of compressibility and solvent structure are sys- tematically incorporated. The coupling of the solute–solvent ...

  2. Double emulsion solvent evaporation techniques used for drug encapsulation.

    Science.gov (United States)

    Iqbal, Muhammad; Zafar, Nadiah; Fessi, Hatem; Elaissari, Abdelhamid

    2015-12-30

    Double emulsions are complex systems, also called "emulsions of emulsions", in which the droplets of the dispersed phase contain one or more types of smaller dispersed droplets themselves. Double emulsions have the potential for encapsulation of both hydrophobic as well as hydrophilic drugs, cosmetics, foods and other high value products. Techniques based on double emulsions are commonly used for the encapsulation of hydrophilic molecules, which suffer from low encapsulation efficiency because of rapid drug partitioning into the external aqueous phase when using single emulsions. The main issue when using double emulsions is their production in a well-controlled manner, with homogeneous droplet size by optimizing different process variables. In this review special attention has been paid to the application of double emulsion techniques for the encapsulation of various hydrophilic and hydrophobic anticancer drugs, anti-inflammatory drugs, antibiotic drugs, proteins and amino acids and their applications in theranostics. Moreover, the optimized ratio of the different phases and other process parameters of double emulsions are discussed. Finally, the results published regarding various types of solvents, stabilizers and polymers used for the encapsulation of several active substances via double emulsion processes are reported. Copyright © 2015 Elsevier B.V. All rights reserved.

  3. Study of solvents alternative for aromatic extraction

    OpenAIRE

    Francisca Maria Rodrigues Mesquita

    2015-01-01

    Aromatic hydrocarbons are chemical compounds of great interest in the petrochemical industry. These are commonly derived from reformed naphtha, which are in multicomponent mixtures with aliphatic hydrocarbons. The separation of these components is realized, generally, the liquid-liquid extraction process. In this process, the sulfolane is the most widely used solvent. However, this has some disadvantages such as high cost. For this reason, many studies are developed by the academic community ...

  4. Solvent extraction of Southern US tar sands

    Energy Technology Data Exchange (ETDEWEB)

    Penney, W.R.

    1990-01-01

    The Department of Chemical Engineering at the University of Arkansas, in association with Diversified Petroleum Recovery, Inc. (DPR) of Little Rock, Arkansas, has been developing a solvent extraction process for the recovery of bitumen from tar sands for the past five years. The unique feature of the process is that the bitumen is recovered from the solvent by contacting with a co-solvent, which causes the bitumen to precipitate. The overall purpose of this project is to study both the technical and economic feasibility of applying this technology for recovery of bitumen from tar sands by (1) investigating the socioeconmic factors which affect (a) plant siting and (b) the market value of recovered bitumen; (2) operating a process demonstration unit at the rate of 1 lb/hr recovered bitumen while producing clean sand and recyclable solvents; and (3) determine the economic conditions which will make a bitumen recovery project economical. DPR has analyzed the historical trends of domestic production, consumption, discoveries and reserves of crude oil. They have started an investigation of the volatility in the price of crude oil and of gasoline prices and of the differential between gasoline and crude oil. DPR continues to analyze the geographical movement and demand for asphalt products. Utah does not appear economically attractive as a site for a bitumen from tar sands asphalt plant. Oklahoma sites are now being studied. This report also contains the quarterly progress report from a University of Nevada study to determine bitumen composition, oxygen uptake rates, and viscosities of Alabama and Utah bitumens. Both reports have been indexed separately for inclusion on the data base.

  5. Coupling of protein dynamics with the solvent

    Science.gov (United States)

    Caliskan, Gokhan; Sauzan, Azzam; Mehtani, Disha; Sokolov, Alexei

    2003-03-01

    Glycerol and trehalose are among the many viscous solvents that are widely used for biostabilization and controlling the dynamics of proteins. It is believed that the suppression of the structural relaxations by high viscosity of solvent is responsible for improved stability in proteins. However, results of [1] and [2] demonstrate stronger suppression of biochemical activity and dynamics of proteins by liquid glycerol than by solid trehalose in a wide temperature range. The authors tried to explain the counterintuitive observations by a possible decoupling of the dynamics of the protein from trehalose. In order to test the validity of this assumption and to investigate the influence of the fast dynamics in proteins, the low frequency Raman scattering spectroscopy technique is used. Both relaxational and vibrational dynamics of glycerol, trehalose, and lysozyme in glycerol and in trehalose are studied in a wide temperature range. Dynamics of lysozyme in glycerol follows the strong temperature dependence of relaxational and vibrational dynamics of the bulk glycerol. On the other hand, the weak temperature dependence of dynamics of lysozyme in trehalose follows exactly the behavior of pure trehalose. This proves that there is a strong dynamic coupling between the protein and the solvents used. Interestingly, stronger relaxations in solid trehalose as compared to liquid glycerol are observed in the GHz region at low temperatures. This could be the reason for the enhanced protein activity observed in trehalose, compared to that in glycerol in this temperature range. Suppression of these fast relaxations should be the key for providing long-term stability to proteins. 1. Sastry, G.M. and N. Agmon, Trehalose prevents myoglobin collapse and preserves its internal mobility. BIOCHEMISTRY, 1997, 36(23): p. 7097-108. 2. Caliskan, G., et al., Influence of solvent on dynamics and stability of a protein. Journal of Non-Crystalline Solids, 2002, 307-310: p. 887-893.

  6. ACETANILIDA: SÍNTESE VERDE SEM SOLVENTE

    Directory of Open Access Journals (Sweden)

    Silvio Cunha

    2015-07-01

    Full Text Available We described herein a solvent-free synthesis of acetanilide developed in the context of green chemistry. The synthetic approach consisted of the reaction of aniline with acetic anhydride without additives, while using smaller amounts of reagents and water than previously described for this undergraduate experiment. The E Factor was 0.6 by experienced chemists and 0.9 by students.

  7. Passivity of lithium in organic solvents

    Energy Technology Data Exchange (ETDEWEB)

    Rahner, D.; Machill, S.; Siury, K. [Dresden Univ. of Technology, Inst. of Physical Chemistry and Electrochemistry, Dresden (Germany)

    1997-09-01

    A short overview concerning the nature of lithium `passivity` and the use of in situ techniques in lithium research will be given in order to emphasize the important role of the properties of the phase-boundary metal/electrolyte. The electrochemical behaviour of lithium is strongly influenced by the formation of a surface layer due to the reduction of the solvent and of the electrolyte. A kinetic model for the layer formation at uncovered lithium surfaces will be suggested. (orig.)

  8. Layered microporous polymers by solvent knitting method.

    Science.gov (United States)

    Wang, Shaolei; Zhang, Chengxin; Shu, Yu; Jiang, Shulan; Xia, Qi; Chen, Linjiang; Jin, Shangbin; Hussain, Irshad; Cooper, Andrew I; Tan, Bien

    2017-03-01

    Two-dimensional (2D) nanomaterials, especially 2D organic nanomaterials with unprecedentedly diverse and controlled structure, have attracted decent scientific interest. Among the preparation strategies, the top-down approach is one of the considered low-cost and scalable strategies to obtain 2D organic nanomaterials. However, some factors of their layered counterparts limited the development and potential applications of 2D organic nanomaterials, such as type, stability, and strict synthetic conditions of layered counterparts. We report a class of layered solvent knitting hyper-cross-linked microporous polymers (SHCPs) prepared by improving Friedel-Crafts reaction and using dichloroalkane as an economical solvent, stable electrophilic reagent, and external cross-linker at low temperature, which could be used as layered counterparts to obtain previously unknown 2D SHCP nanosheets by method of ultrasonic-assisted solvent exfoliation. This efficient and low-cost strategy can produce previously unreported microporous organic polymers with layered structure and high surface area and gas storage capacity. The pore structure and surface area of these polymers can be controlled by tuning the chain length of the solvent, the molar ratio of AlCl3, and the size of monomers. Furthermore, we successfully obtain an unprecedentedly high-surface area HCP material (3002 m2 g-1), which shows decent gas storage capacity (4.82 mmol g-1 at 273 K and 1.00 bar for CO2; 12.40 mmol g-1 at 77.3 K and 1.13 bar for H2). This finding provides an opportunity for breaking the constraint of former knitting methods and opening up avenues for the design and synthesis of previously unknown layered HCP materials.

  9. Solvent induced modifications to fiber nanostructure and morphology for 12HSA molecular gels

    Science.gov (United States)

    Gao, Jie

    Molecular organogels are thermo reversible quasi-solid materials, which are formed by low molecular weight organogelators (LMOGs) undergoing supramolecular aggregation via non-covalent interactions, forming a three-dimensional fibrillar network. Numerous applications of molecular organogels are been investigated as edible oils, drug release matrices and personal care products. The chemistry of the organic phase (i.e., solvent) influences every level of structure in organogels. Different solvents induce LMOG to assemble into "crystal like" fibers, which have more than one crystal form, lamellar arrangement and domain size. Differences in these solid states are known to affect the macroscopic properties of the gel, including critical gelator concentration (CGC), melting point, melting enthalpy and opacity.12-hydroxystearic acid (12HSA) was examined in several classes of organic solvents with different function groups. These gels, sols or precipitates were analyzed using a series of techniques including: powder x-ray diffraction (XRD), differential scanning calorimetry (DSC), fourier-transform infrared spectroscopy (FT-IR), pulsed nuclear magnetic resonance spectroscopy (pNMR) and microscopy. Specifically, certain solvents caused 12HSA to self-assemble into a triclinic parallel polymorphic form with subcell spacing of ~4.6, 3.9, and 3.8 A and an interdigitated unit cell with a lamellar arrangement (38~44 A). This polymorphic form corresponded to a less effective sphereultic supramolecular crystalline network, which immobilizes solvents at CGC greater than 1.5 wt %. The other group of solvents induce a hexagonal subcell spacing (i.e., unit sub cell spacing ~4.1 A) and are arranged in a multi lamellar fashion with a unit cell greater than the bimolecular length of 12HSA (~54 A).This polymorphic form corresponds to fibrillar aggregates with a CGC less than 1 wt %.

  10. Percolation characteristics of solvent invasion in rough fractures under miscible conditions

    Science.gov (United States)

    Korfanta, M.; Babadagli, T.; Develi, K.

    2017-10-01

    Surface roughness and flow rate effects on the solvent transport under miscible conditions in a single fracture are studied. Surface replicas of seven different rocks (marble, granite, and limestone) are used to represent different surface roughness characteristics each described by different mathematical models including three fractal dimensions. Distribution of dyed solvent is investigated at various flow rate conditions to clarify the effect of roughness on convective and diffusive mixing. After a qualitative analysis using comparative images of different rocks, the area covered by solvent with respect to time is determined to conduct a semi-quantitative analysis. In this exercise, two distinct zones are identified, namely the straight lines obtained for convective (early times) and diffusive (late times) flow. The bending point between these two lines is used to point the transition between the two zones. Finally, the slopes of the straight lines and the bending points are correlated to five different roughness parameters and the rate (Peclet number). It is observed that both surface roughness and flow rate have significant effect on solvent spatial distribution. The largest area covered is obtained at moderate flow rates and hence not only the average surface roughness characteristic is important, but coessentially total fracture surface area needs to be considered when evaluating fluid distribution. It is also noted that the rate effect is critically different for the fracture samples of large grain size (marbles and granite) compared to smaller grain sizes (limestones). Variogram fractal dimension exhibits the strongest correlation with the maximum area covered by solvent, and display increasing trend at the moderate flow rates. Equations with variogram surface fractal dimension in combination with any other surface fractal parameter coupled with Peclet number can be used to predict maximum area covered by solvent in a single fracture, which in turn can be

  11. Dynamics of solvent-free grafted nanoparticles

    KAUST Repository

    Chremos, Alexandros

    2012-01-01

    The diffusivity and structural relaxation characteristics of oligomer-grafted nanoparticles have been investigated with simulations of a previously proposed coarse-grained model at atmospheric pressure. Solvent-free, polymer-grafted nanoparticles as well as grafted nanoparticles in a melt were compared to a reference system of bare (ungrafted) particles in a melt. Whereas longer chains lead to a larger hydrodynamic radius and lower relative diffusivity for grafted particles in a melt, bulk solvent-free nanoparticles with longer chains have higher relative diffusivities than their short chain counterparts. Solvent-free nanoparticles with short chains undergo a glass transition as indicated by a vanishing diffusivity, diverging structural relaxation time and the formation of body-centered-cubic-like order. Nanoparticles with longer chains exhibit a more gradual increase in the structural relaxation time with decreasing temperature and concomitantly increasing particle volume fraction. The diffusivity of the long chain nanoparticles exhibits a minimum at an intermediate temperature and volume fraction where the polymer brushes of neighboring particles overlap, but must stretch to fill the interparticle space. © 2012 American Institute of Physics.

  12. Critical reading and critical thinking

    Directory of Open Access Journals (Sweden)

    Loni Kreis Taglieber

    2003-01-01

    Full Text Available The purpose of this paper is to provide, for L1 and L2 reading and writing teachers, a brief overview of the literature about critical reading and higher level thinking skills. The teaching of these skills is still neglected in some language classes in Brazil, be it in L1 or in L2 classes. Thus, this paper may also serve as a resource guide for L1 and/or L2 reading and writing teachers who want to incorporate critical reading and thinking into their classes. In modern society, even in everyday life people frequently need to deal with complicated public and political issues, make decisions, and solve problems. In order to do this efficiently and effectively, citizens must be able to evaluate critically what they see, hear, and read. Also, with the huge amount of printed material available in all areas in this age of “information explosion” it is easy to feel overwhelmed. But often the information piled up on people’s desks and in their minds is of no use due to the enormous amount of it.

  13. Critical Mass

    CERN Multimedia

    AUTHOR|(CDS)2070299

    2017-01-01

    Critical Mass is a cycling event typically held on the last Friday of every month; its purpose is not usually formalized beyond the direct action of meeting at a set location and time and traveling as a group through city or town streets on bikes. The event originated in 1992 in San Francisco; by the end of 2003, the event was being held in over 300 cities around the world. At CERN it is held once a year in conjunction with the national Swiss campaing "Bike to work".

  14. Accumulation of solvent-soluble and solvent-insoluble antioxidant phenolics in edible bean sprouts: implication of germination

    OpenAIRE

    Ren-You Gan; Wing-Yee Lui; Ming-Fu Wang; Zhong-Quan Sui

    2016-01-01

    Background: Edible bean sprouts are popular fresh vegetables widely recognized for their nutritional quality. However, while their antioxidant capacity and phenolic composition in both solvent-soluble and solvent-insoluble extracts has not been systematically evaluated. Methods: The antioxidant capacity and phenolic composition in both solvent-soluble and solvent-insoluble fractions of 12 cultivars of edible bean sprouts were evaluated, and relationships of antioxidant cap...

  15. Linearized cloudpoint curve correlation for ternary systems consisting of one polymer, one solvent and one non-solvent

    NARCIS (Netherlands)

    Boom, R.M.; Boom, R.M.; van den Boomgaard, Anthonie; van den Berg, J.W.A.; Smolders, C.A.; Smolders, C.A.

    1993-01-01

    A linear correlation function is found for cloudpoint composition curves of ternary systems consisting of one polymer, one solvent and one non-solvent. The conditions for validity of this correlation function appear to be that the polymer is strongly incompatible with the non-solvent, and that only

  16. Deep Eutectic Solvents as Efficient Media for the Extraction and Recovery of Cynaropicrin from Cynara cardunculus L. Leaves.

    Science.gov (United States)

    de Faria, Emanuelle L P; do Carmo, Rafael S; Cláudio, Ana Filipa M; Freire, Carmen S R; Freire, Mara G; Silvestre, Armando J D

    2017-10-30

    In recent years a high demand for natural ingredients with nutraceutical properties has been witnessed, for which the development of more environmentally-friendly and cost-efficient extraction solvents and methods play a primary role. In this perspective, in this work, the application of deep eutectic solvents (DES), composed of quaternary ammonium salts and organic acids, as alternative solvents for the extraction of cynaropicrin from Cynara cardunculus L. leaves was studied. After selecting the most promising DES, their aqueous solutions were investigated, allowing to obtain a maximum cynaropicrin extraction yield of 6.20 wt %, using 70 wt % of water. The sustainability of the extraction process was further optimized by carrying out several extraction cycles, reusing either the biomass or the aqueous solutions of DES. A maximum cynaropicrin extraction yield of 7.76 wt % by reusing the solvent, and of 8.96 wt % by reusing the biomass, have been obtained. Taking advantage of the cynaropicrin solubility limit in aqueous solutions, water was added as an anti-solvent, allowing to recover 73.6 wt % of the extracted cynaropicrin. This work demonstrates the potential of aqueous solutions of DES for the extraction of value-added compounds from biomass and the possible recovery of both the target compounds and solvents.

  17. Analysis of organochlorine pesticides in wine by solvent bar microextraction coupled with gas chromatography with tandem mass spectrometry detection.

    Science.gov (United States)

    Chia, Kan-Jung; Huang, Shang-Da

    2006-01-01

    A solvent bar microextraction (SBME) technique combined with gas chromatography/tandem mass spectrometry (GC/MS/MS), for the determination of selected organochlorine pesticides (OCPs) in wine samples, is described. In this work the OCPs were extracted and dissolved in a 2-microL aliquot of organic extraction solvent (n-tetradecane) confined within a 1.7-cm length of hollow fiber. Both ends of the hollow fiber (solvent bar) were sealed, and it was placed in an aqueous sample solution for extraction. The effects of solvent selection, sample agitation, extraction time, extraction temperature, and salt concentration on the SBME performance were optimized. The influence of aqueous sample/organic solvent phase ratio was further investigated in detail. High enrichments (1900-7100-fold) could be obtained at an aqueous sample/organic solvent volume ratio of 20 mL/2 microL in this study. Good extraction reproducibility was obtained with relative standard deviation (RSD) values below 12.6%. Comparisons of sensitivity and precision between SBME and dynamic hollow-fiber liquid-phase microextraction were also investigated.

  18. Switchable polarity solvent for liquid phase microextraction of Cd(II) as pyrrolidinedithiocarbamate chelates from environmental samples

    Energy Technology Data Exchange (ETDEWEB)

    Yilmaz, Erkan, E-mail: kimyager_erkan@hotmail.com; Soylak, Mustafa, E-mail: soylak@erciyes.edu.tr

    2015-07-30

    A switchable polarity solvent was synthesized from triethylamine (TEA)/water/CO{sub 2} (Dry ice) via proton transfer reaction has been used for the microextraction of cadmium(II) as pyrrolidinedithiocarbamate (APDC) chelate. Cd(II)-APDC chelate was extracted into the switchable polarity solvent drops by adding 2 mL 10 M sodium hydroxide solution. Analytical parameters affecting the complex formation and microextraction efficiency such as pH, amount of ligand, volume of switchable polarity solvent and NaOH, sample volume were optimized. The effects of foreign ions were found tolerably. Under optimum conditions, the detection limit was 0.16 μg L{sup −1} (3Sb/m, n = 7) and the relative standard deviation was 5.4% (n = 7). The method was validated by the analysis of certified reference materials (TMDA-51.3 fortified water, TMDA-53.3 fortified water and SPS-WW2 waste water, 1573a Tomato Leaves and Oriental Basma Tobacco Leaves (INCT-OBTL-5)) and addition/recovery tests. The method was successfully applied to determination of cadmium contents of water, vegetable, fruit and cigarette samples. - Highlights: • Switchable polarity solvent was synthesized from triethylamine (TEA)/water/CO{sub 2}. • The switchable polarity solvent has been used for the microextraction of cadmium(II). • The important factors were optimized. • The method was applied to determination of cadmium in real samples.

  19. Neurophysiological findings among workers exposed to organic solvents

    Energy Technology Data Exchange (ETDEWEB)

    Seppaelaeinen, A.M.

    1982-01-01

    Neurophysiological findings among patients with solvent poisoning and among groups with long-term occupational exposure to various solvents are reviewed. Hydrocarbons with six carbon atoms have been shown to cause peripheral neuropathy, which can be revealed with electroneurography and electromyography. Various mixtures of solvents and carbon disulfide have caused similar types of abnormalities. Abnormal electroencephalograms have been reported for patients with solvent poisoning and also connected to occupational exposure. Visual evoked potentials have rarely been applied to study of solvent effects, latency increases have been reported. Multiple lesions within the central and peripheral nervous system should arouse a thought of possible toxic etiology.

  20. The Development of a Microscale Continuous Hot Solvent Extractor

    Science.gov (United States)

    Wesolowski, Steve S.; Mulcahy, Thomas; Zafoni, Christina M.; Wesolowski, Wayne E.

    1999-08-01

    The extraction of soluble materials from organic samples plays an important role in many industries. For example, extraction of oils and grease from soil samples using traditional Soxhlet extractors is an essential procedure in waste management laboratories. These extractors use from 25 to 1000 mL of solvent per sample and the waste solvent is typically distilled or simply disposed of upon completion of the extraction. To minimize the waste solvent produced, we have developed a microscale continuous hot solvent extractor that effectively extracts 100-500-mg samples using about 4 mL of solvent.

  1. Influence of processing procedure on the quality of Radix Scrophulariae: a quantitative evaluation of the main compounds obtained by accelerated solvent extraction and high-performance liquid chromatography.

    Science.gov (United States)

    Cao, Gang; Wu, Xin; Li, Qinglin; Cai, Hao; Cai, Baochang; Zhu, Xuemei

    2015-02-01

    An improved high-performance liquid chromatography with diode array detection combined with accelerated solvent extraction method was used to simultaneously determine six compounds in crude and processed Radix Scrophulariae samples. Accelerated solvent extraction parameters such as extraction solvent, temperature, number of cycles, and analysis procedure were systematically optimized. The results indicated that compared with crude Radix Scrophulariae samples, the processed samples had lower contents of harpagide and harpagoside but higher contents of catalpol, acteoside, angoroside C, and cinnamic acid. The established method was sufficiently rapid and reliable for the global quality evaluation of crude and processed herbal medicines. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Ultrasound-assisted green solvent extraction of high-added value compounds from microalgae Nannochloropsis spp.

    Science.gov (United States)

    Parniakov, O; Apicella, E; Koubaa, M; Barba, F J; Grimi, N; Lebovka, N; Pataro, G; Ferrari, G; Vorobiev, E

    2015-12-01

    The aim of this work was to investigate ultrasound (US)-assisted green solvent extraction of valuable compounds from the microalgae Nannochloropsis spp. Individual green solvents (water, ethanol (EtOH), dimethyl sulfoxide (DMSO)) and binary mixture of solvents (water-DMSO and water-EtOH) were used for the extraction procedures. Maximum total phenolic compounds yield (Yp ≈ 0.33) was obtained after US pre-treatment (W=400 W, 15 min), being almost 5-folds higher compared to that found for the untreated samples and aqueous extraction (Yp ≈ 0.06). The highest yield of total chlorophylls (Yc ≈ 0.043) was obtained after US (W=400 W, 7.5 min), being more than 9-folds higher than those obtained for the untreated samples and aqueous extraction (Yc ≈ 0.004). The recovery efficiency decreased as DMSO>EtOH>H2O. The optimal conditions to recover phenolic compounds and chlorophylls from microalgae were obtained after US pre-treatment (400 W, 5 min), binary mixtures of solvents (water-DMSO and water-EtOH) at 25-30%, and microalgae concentration of 10%. Copyright © 2015 Elsevier Ltd. All rights reserved.

  3. Toxicity of Stemona root against onion cutworm by using different contacting methods and solvents.

    Science.gov (United States)

    Sanguanpong, U; Hummel, H E

    2008-01-01

    Roots of Stemona tuberoso have been extracted by using fixed-bed contacting method with serial and parallel technique. In order to extract secondary metabolites from roots of Stemona sp., various organic solvents with different polarities were employed. Optimal solvents for the extraction of effective ingredients from root were determined. The results showed that in most cases the yields of crude extract were highest by using parallel technique rather than serial technique. The highest yields of crude extract by using both techniques were obtained with acetone, followed by water, ethanol, methanol, dichloromethane and hexane, respectively. Furthermore it was found that the L-a-b value and the total soluble solid (TSS) value in terms of degree Brix of crude extracts were different depending on choice of organic solvents. In particular, dichloromethane extracted more total soluble solid from plant material with both techniques, followed by hexane, ethanol, acetone, water and methanol, respectively. The biological activities of different crude extracts from S. tuberosa against Spodoptera exigua were experimentally determined. It was observed that the crude extract with highest toxicity to Larvae was obtained with high polarity solvents such as water, methanol and ethanol. The results suggested that water extract tested under high concentration could promote higher mortality. On the other hand, hexane extract caused approximately 30 % mortality with highest concentration at 15% w/w. Dichloromethane and acetone extract could be considered of similar efficiency.

  4. Ultrasonic-assisted extraction of essential oil from Botryophora geniculate using different extracting solvents

    Science.gov (United States)

    Habibullah, Wilfred, Cecilia Devi

    2016-11-01

    This study compares the performance of ionic liquids to substitute conventional solvents (hexane, dichloromethane and methanol) to extract essential oil from Botryophora geniculate plant. Two different Ionic liquids ([C3MIM][Ac], [C4MIM][Ac]) with co-solvent diethyl ether were used in the ultrasonic-assisted extraction. The effect of various experimental conditions such as time, temperature and solvent were studied. Gas chromatography-mass spectroscopy (GC-MS) was used to analyze essential oils. The results showed that in ultrasonic-assisted extraction using ionic liquids as a solvent gave highest yield (9.5%) in 30 min at temperature 70°C. When using ultrasonic bath with hexane, dichloromethane and methanol, yields was (3.34%), (3.6%) and (3.81%) at 90 min, respectively were obtained. The ultrasonic-assisted extraction under optimal extraction conditions (time 30 min, temperature of 70°C) gave the best yield for the essential oil extraction.

  5. Solvent Effects on IR Modes of (R)-3-METHYLCYCLOPENTANONE Conformers: a Computational Investigation

    Science.gov (United States)

    Al-Basheer, Watheq

    2013-06-01

    Density Functional Theory (DFT) calculations of infrared spectra for the optimized geometries of R-(+)-3-methylcyclopentanone (R3MCP) equatorial-methyl and axial-methyl conformers were performed in 11 common solvents of wide polarity range, in the framework of polarizable continuum model (PCM). DFT correlation function type B3LYP using a powerful basis set (aug-cc-pVDZ) yielded different linear correlation between solvent polarity and R3MCP equatorial and axial conformers IR modes frequencies, intensities, and enthalpies (W. Al-Basheer, J. Sol. Chem. 41, 1495-1506 (2012)). DFT calculations of the R3MCP equatorial and axial conformer dipole moment components in 3D were also carried out and found to have a linear correlation with solvent polarity (W. Al-Basheer et al, J. Phys. Chem. A 111(12), 2293-2298 (2007)). An observed trend for a Hypsochromic (blue) shift in the equatorial conformer IR frequencies, in comparison to Bathochromic (red) shift for the axial-methyl conformer IR modes as a function of solvent polarity increase.

  6. Cleaning Spent Bleaching Clay through Using Solvent Extraction Method and RSM Statistical Approach

    Directory of Open Access Journals (Sweden)

    mahsa shahi

    2015-07-01

    Full Text Available Bleaching clay refers to clays that in their natural or activated state have the capacity to absorb dyes and other remaining undesirable ingredients from edible oil during its purification processes. Thus, the most important function of bleaching clay is to improve the appearance, flavor, odor, and stability of the final oil product. Hexane, acetone, and methyl ethyl ketone were used as the solvents in this research, and RSM (response surface methodology was employed for determining the optimal parameters. The variable parameters included the solvent to clay ratio (SCR and the extraction time. Results showed methyl ethyl ketone with the final oil removal efficiency of 61.3% was superior to hexane and acetone, with efficiencies of 52.7 and 59.1%, respectively. Under the best laboratory conditions and using RSM, the highest extraction efficiency was 5.97 ml/g for the ketone solvents (acetone and methyl ethyl ketone at the extraction time of 3 minutes and 6 seconds, and 5.92 ml/g for hexane at the extraction time of 24 minutes and 30 seconds. Key words: Cleaning, Spent Bleaching Clay, Solvent Extraction, Response Surface Methodology (RSM, Oil Purification

  7. Cleaning Spent Bleaching Clay through Using Solvent Extraction Method and RSM Statistical Approach

    Directory of Open Access Journals (Sweden)

    Mahsa Shahi

    2015-12-01

    Full Text Available Abstract. Bleaching clay refers to clays that in their natural or activated state have the capacity to absorb dyes and other remaining undesirable ingredients from edible oil during its purification processes. Thus, the most important function of bleaching clay is to improve the appearance, flavor, odor, and stability of the final oil product. Hexane, acetone, and methyl ethyl ketone were used as the solvents in this research, and RSM (response surface methodology was employed for determining the optimal parameters. The variable parameters included the solvent to clay ratio (SCR and the extraction time. Results showed methyl ethyl ketone with the final oil removal efficiency of 61.3% was superior to hexane and acetone, with efficiencies of 52.7 and 59.1%, respectively. Under the best laboratory conditions and using RSM, the highest extraction efficiency was 5.97 ml/g for the ketone solvents (acetone and methyl ethyl ketone at the extraction time of 3 minutes and 6 seconds, and 5.92 ml/g for hexane at the extraction time of 24 minutes and 30 seconds.Keywords: Cleaning, Spent Bleaching Clay, Solvent Extraction, Response Surface Methodology (RSM, Oil Purification

  8. Wet in situ transesterification of microalgae using ethyl acetate as a co-solvent and reactant.

    Science.gov (United States)

    Park, Jeongseok; Kim, Bora; Chang, Yong Keun; Lee, Jae W

    2017-04-01

    This study addresses wet in situ transesterification of microalgae for the production of biodiesel by introducing ethyl acetate as both reactant and co-solvent. Ethyl acetate and acid catalyst are mixed with wet microalgae in one pot and the mixture is heated for simultaneous lipid extraction and transesterification. As a single reactant and co-solvent, ethyl acetate can provide higher FAEE yield and more saccharification of carbohydrates than the case of binary ethanol and chloroform as a reactant and a co-solvent. The optimal yield was 97.8wt% at 114°C and 4.06M catalyst with 6.67mlEtOAC/g dried algae based on experimental results and response surface methodology (RSM). This wet in situ transesterification of microalgae using ethyl acetate doesn't require an additional co-solvent and it also promises more economic benefit as combining extraction and transesterification in a single process. Copyright © 2017 Elsevier Ltd. All rights reserved.

  9. Nonhazardous solvent composition and method for cleaning metal surfaces

    Science.gov (United States)

    Googin, J.M.; Simandl, R.F.; Thompson, L.M.

    1993-05-04

    A solvent composition for displacing greasy and oily contaminants as well as water and/or aqueous residue from metallic surfaces, especially surfaces of radioactive materials so that such surfaces can be wiped clean of the displaced contaminants, water and/or aqueous residue. The solvent composition consists essentially of a blend of nonpolar aliphatic hydrocarbon solvent having a minimum flash point of about 140 F and 2 to 25 volume percent of a polar solvent having a flash point sufficiently high so as to provide the solvent composition with a minimum flash point of at least 140 F. The solvent composition is nonhazardous so that when it is used to clean the surfaces of radioactive materials the waste in the form of paper or cloth wipes, lab coats and the like used in the cleaning operation is not considered to be mixed waste composed of a hazardous solvent and a radioactive material.

  10. Optimization of Bistable Viscoelastic Systems

    DEFF Research Database (Denmark)

    Jensen, Kristian Ejlebjærg; Szabo, Peter; Okkels, Fridolin

    2014-01-01

    the critical pressure gives rise to increased hydraulic resistance. We have combined a state-of-the-art implementation for viscoelastic flow modeling with topology optimization in a high level finite element package (COMSOL). We use this framework on the cross geometry with the aim to reduce the critical...

  11. Dictionary criticism

    DEFF Research Database (Denmark)

    Nielsen, Sandro

    2018-01-01

    Dictionary criticism is part of the lexicographical universe and reviewing of electronic and printed dictionaries is not an exercise in linguistics or in subject fields but an exercise in lexicography. It does not follow from this that dictionary reviews should not be based on a linguistic approach......, but that the linguistic approach is only one of several approaches to dictionary reviewing. Similarly, the linguistic and factual competences of reviewers should not be relegated to an insignificant position in the review process. Moreover, reviewers should define the object of their reviews, the dictionary, as a complex...... information tool with several components and in terms of significant lexicographical features: lexicographical functions, data and structures. This emphasises the fact that dictionaries are much more than mere vessels of linguistic categories, namely lexicographical tools that have been developed to fulfil...

  12. Anti-Solvent Crystallization Strategies for Highly Efficient Perovskite Solar Cells

    Directory of Open Access Journals (Sweden)

    Maria Konstantakou

    2017-09-01

    Full Text Available Solution-processed organic-inorganic halide perovskites are currently established as the hottest area of interest in the world of photovoltaics, ensuring low manufacturing cost and high conversion efficiencies. Even though various fabrication/deposition approaches and device architectures have been tested, researchers quickly realized that the key for the excellent solar cell operation was the quality of the crystallization of the perovskite film, employed to assure efficient photogeneration of carriers, charge separation and transport of the separated carriers at the contacts. One of the most typical methods in chemistry to crystallize a material is anti-solvent precipitation. Indeed, this classical precipitation method worked really well for the growth of single crystals of perovskite. Fortunately, the method was also effective for the preparation of perovskite films by adopting an anti-solvent dripping technique during spin-coating the perovskite precursor solution on the substrate. With this, polycrystalline perovskite films with pure and stable crystal phases accompanied with excellent surface coverage were prepared, leading to highly reproducible efficiencies close to 22%. In this review, we discuss recent results on highly efficient solar cells, obtained by the anti-solvent dripping method, always in the presence of Lewis base adducts of lead(II iodide. We present all the anti-solvents that can be used and what is the impact of them on device efficiencies. Finally, we analyze the critical challenges that currently limit the efficacy/reproducibility of this crystallization method and propose prospects for future directions.

  13. Changing the Mechanism for CO 2 Hydrogenation Using Solvent-Dependent Thermodynamics

    Energy Technology Data Exchange (ETDEWEB)

    Burgess, Samantha A. [Catalysis Science Group, Pacific Northwest National Laboratory, P.O. Box 999 Richland WA 99352 USA; Appel, Aaron M. [Catalysis Science Group, Pacific Northwest National Laboratory, P.O. Box 999 Richland WA 99352 USA; Linehan, John C. [Catalysis Science Group, Pacific Northwest National Laboratory, P.O. Box 999 Richland WA 99352 USA; Wiedner, Eric S. [Catalysis Science Group, Pacific Northwest National Laboratory, P.O. Box 999 Richland WA 99352 USA

    2017-10-23

    A critical scientific challenge for utilization of CO2 is the development of catalyst systems that do not depend upon expensive or environmentally unfriendly reagents, such as precious metals, strong organic bases, and organic solvents. We have used thermodynamic insights to predict and demonstrate that the HCoI(dmpe)2 catalyst system, previously described for use in organic solvents, can hydrogenate CO2 to formate in water with bicarbonate as the only added reagent. Replacing tetrahydrofuran as the solvent with water changes the mechanism for catalysis by altering the thermodynamics for hydride transfer to CO2 from a key dihydride intermediate. The need for a strong organic base was eliminated by performing catalysis in water due to the change in mechanism. These studies demonstrate that the solvent plays a pivotal role in determining the reaction thermodynamics and thereby catalytic mechanism and activity. The research was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Division of Chemical Sciences, Geosciences, and Biosciences. Pacific Northwest National Laboratory is operated by Battelle for the U.S. Department of Energy.

  14. Dual fluorescence of ellipticine: excited state proton transfer from solvent versus solvent mediated intramolecular proton transfer.

    Science.gov (United States)

    Banerjee, Sanghamitra; Pabbathi, Ashok; Sekhar, M Chandra; Samanta, Anunay

    2011-08-25

    Photophysical properties of a natural plant alkaloid, ellipticine (5,11-dimethyl-6H-pyrido[4,3-b]carbazole), which comprises both proton donating and accepting sites, have been studied in different solvents using steady state and time-resolved fluorescence techniques primarily to understand the origin of dual fluorescence that this molecule exhibits in some specific alcoholic solvents. Ground and excited state calculations based on density functional theory have also been carried out to help interpretation of the experimental data. It is shown that the long-wavelength emission of the molecule is dependent on the hydrogen bond donating ability of the solvent, and in methanol, this emission band arises solely from an excited state reaction. However, in ethylene glycol, both ground and excited state reactions contribute to the long wavelength emission. The time-resolved fluorescence data of the system in methanol and ethylene glycol indicates the presence of two different hydrogen bonded species of ellipticine of which only one participates in the excited state reaction. The rate constant of the excited state reaction in these solvents is estimated to be around 4.2-8.0 × 10(8) s(-1). It appears that the present results are better understood in terms of solvent-mediated excited state intramolecular proton transfer reaction from the pyrrole nitrogen to the pyridine nitrogen leading to the formation of the tautomeric form of the molecule rather than excited state proton transfer from the solvents leading to the formation of the protonated form of ellipticine. © 2011 American Chemical Society

  15. Next Generation Solvent Development for Caustic-Side Solvent Extraction of Cesium

    Energy Technology Data Exchange (ETDEWEB)

    Moyer, Bruce A. [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States); Birdwell, Joseph F. [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States); Bonnesen, Peter V. [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States); Bruffey, Stephanie [Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)

    2014-03-01

    This report summarizes the FY 2010 and 2011 accomplishments at Oak Ridge National Laboratory (ORNL) in developing the Next Generation Caustic-Side Solvent Extraction (NG-CSSX) process, referred to commonly as the Next Generation Solvent (NGS), under funding from the U.S. Department of Energy, Office of Environmental Management (DOE-EM), Office of Technology Innovation and Development. The primary product of this effort is a process solvent and preliminary flowsheet capable of meeting a target decontamination factor (DF) of 40,000 for worst-case Savannah River Site (SRS) waste with a concentration factor of 15 or higher in the 18-stage equipment configuration of the SRS Modular Caustic-Side Solvent Extraction Unit (MCU). In addition, the NG-CSSX process may be readily adapted for use in the SRS Salt Waste Processing Facility (SWPF) or in supplemental tank-waste treatment at Hanford upon appropriate solvent or flowsheet modifications. Efforts in FY 2010 focused on developing a solvent composition and process flowsheet for MCU implementation. In FY 2011 accomplishments at ORNL involved a wide array of chemical-development activities and testing up through single-stage hydraulic and mass-transfer tests in 5-cm centrifugal contactors. Under subcontract from ORNL, Argonne National Laboratory (ANL) designed a preliminary flowsheet using ORNL cesium distribution data, and Tennessee Technological University confirmed a chemical model for cesium distribution ratios (DCs) as a function of feed composition. Inter laboratory efforts were coordinated with complementary engineering tests carried out (and reported separately) by personnel at Savannah River National Laboratory (SRNL) and Savannah River Remediation (SRR) with helpful advice by Parsons Engineering and General Atomics on aspects of possible SWPF implementation.

  16. Next Generation Solvent (NGS): Development for Caustic-Side Solvent Extraction of Cesium

    Energy Technology Data Exchange (ETDEWEB)

    Moyer, Bruce A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Birdwell, Jr, Joseph F. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Bonnesen, Peter V. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Bruffey, Stephanie H. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Delmau, Laetitia Helene [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Duncan, Nathan C. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Ensor, Dale [Tennessee Technological Univ., Cookeville, TN (United States); Hill, Talon G. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Lee, Denise L. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Rajbanshi, Arbin [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Roach, Benjamin D. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Szczygiel, Patricia L. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Sloop, Jr., Frederick V. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Stoner, Erica L. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Williams, Neil J. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2014-03-01

    This report summarizes the FY 2010 and 2011 accomplishments at Oak Ridge National Laboratory (ORNL) in developing the Next Generation Caustic-Side Solvent Extraction (NG-CSSX) process, referred to commonly as the Next Generation Solvent (NGS), under funding from the U.S. Department of Energy, Office of Environmental Management (DOE-EM), Office of Technology Innovation and Development. The primary product of this effort is a process solvent and preliminary flowsheet capable of meeting a target decontamination factor (DF) of 40,000 for worst-case Savannah River Site (SRS) waste with a concentration factor of 15 or higher in the 18-stage equipment configuration of the SRS Modular Caustic-Side Solvent Extraction Unit (MCU). In addition, the NG-CSSX process may be readily adapted for use in the SRS Salt Waste Processing Facility (SWPF) or in supplemental tank-waste treatment at Hanford upon appropriate solvent or flowsheet modifications. Efforts in FY 2010 focused on developing a solvent composition and process flowsheet for MCU implementation. In FY 2011 accomplishments at ORNL involved a wide array of chemical-development activities and testing up through single-stage hydraulic and mass-transfer tests in 5-cm centrifugal contactors. Under subcontract from ORNL, Argonne National Laboratory (ANL) designed a preliminary flowsheet using ORNL cesium distribution data, and Tennessee Technological University confirmed a chemical model for cesium distribution ratios (DCs) as a function of feed composition. Interlaboratory efforts were coordinated with complementary engineering tests carried out (and reported separately) by personnel at Savannah River National Laboratory (SRNL) and Savannah River Remediation (SRR) with helpful advice by Parsons Engineering and General Atomics on aspects of possible SWPF implementation.

  17. Solvent Effects upon Electrochemical Kinetics: Influences of Interfacial Solvation and Solvent Relaxation Dynamics.

    Science.gov (United States)

    1984-09-01

    solvent, as well as other environmental influences upon LGcorrls conventionally divided into so-called "intrinsic" and " thermodynamic " (or "extrinsic...upon the thermodynamic driving force at a given electrode potential E, whereas the latter is associated with the solvent contribution to the free-energy...listed; electrolyte was 0.5 I. NaCl04 + 3 mM HCl0 4 , except for Cr(H 3 ) 6 3+ reduction which was measured in 40 mI La(CiO4)3 + 3 mM hClO4 - bobserved

  18. Compound forming extractants, solvating solvents and inert solvents IUPAC chemical data series

    CERN Document Server

    Marcus, Y; Kertes, A S

    2013-01-01

    Equilibrium Constants of Liquid-Liquid Distribution Reactions, Part III: Compound Forming Extractants, Solvating Solvents, and Inert Solvents focuses on the compilation of equilibrium constants of various compounds, such as acids, ions, salts, and aqueous solutions. The manuscript presents tables that show the distribution reactions of carboxylic and sulfonic acid extractants and their dimerization and other reactions in the organic phase and extraction reactions of metal ions from aqueous solutions. The book also states that the inorganic anions in these solutions are irrelevant, since they d

  19. Comparison of microwave hydrodistillation and solvent-free microwave extraction of essential oil from Melaleuca leucadendra Linn

    Science.gov (United States)

    Ismanto, A. W.; Kusuma, H. S.; Mahfud, M.

    2017-12-01

    The comparison of solvent-free microwave extraction (SFME) and microwave hydrodistillation (MHD) in the extraction of essential oil from Melaleuca leucadendra Linn. was examined. Dry cajuput leaves were used in this study. The purpose of this study is also to determine optimal condition (microwave power). The relative electric consumption of SFME and MHD methods are both showing 0,1627 kWh/g and 0,3279 kWh/g. The results showed that solvent-free microwave extraction methods able to reduce energy consumption and can be regarded as a green technique for extraction of cajuput oil.

  20. Hydrogen-bonding study of photoexcited 4-nitro-1,8-naphthalimide in hydrogen-donating solvents

    OpenAIRE

    Cao Jianfang; Wu Hongmei; Zheng Yue; Nie Fangyuan; Li Ming; Zou Chenchen

    2016-01-01

    The solute–solvent interactions of 4-nitro-1,8-naphthalimide (4NNI) as a hydrogen bond acceptor in hydrogen donating methanol (MeOH) solvent in electronic excited states were investigated by means of the time-dependent density functional theory(TDDFT). We calculated the S0 state geometry optimizations, electronic transition energies and corresponding oscillation strengths of the low-lying electronically excited states for the isolated 4NNi and hydrogen-bonded 4NNi-(MeOH)1,4 complexes using th...

  1. Solvent effects on infrared spectra of progesterone in CHCl3/cyclo-C6H12 binary solvent systems.

    Science.gov (United States)

    Liu, Qing; Wang, Xiao-Yan; Zhang, Hui

    2007-01-01

    The infrared spectroscopy studies of the C3 and C20 carbonyl stretching vibrations (upsilon(C=O)) of progesterone in CHCl3/cyclo-C6H12 binary solvent systems were undertaken to investigate the solute-solvent interactions. With the mole fraction of CHC13 in the binary solvent mixtures increase, three types of C3 and C20 carbonyl stretching vibration band of progesterone are observed, respectively. The assignments of upsilon(C=O) of progesterone are discussed in detail. In the CHCl3-rich binary solvent systems or pure CHCl3 solvent, two kinds of solute-solvent hydrogen bonding interactions coexist for C20 C=O. Comparisons are drawn for the solvent sensitivities of upsilon(C=O) for acetophenone and 5alpha-androstan-3,17-dione, respectively.

  2. Scenarios Evaluation Tool for Chlorinated Solvent MNA

    Energy Technology Data Exchange (ETDEWEB)

    Vangelas, Karen; Michael J. Truex; Charles J. Newell; Brian Looney

    2007-02-28

    Over the past three decades, much progress has been made in the remediation of chlorinated solvents from the subsurface. Yet these pervasive contaminants continue to present a significant challenge to the U.S. Department of Energy (DOE), other federal agencies, and other public and private organizations. The physical and chemical properties of chlorinated solvents make it difficult to rapidly reach the low concentrations typically set as regulatory limits. These technical challenges often result in high costs and long remediation time frames. In 2003, the DOE through the Office of Environmental Management funded a science-based technical project that uses the U.S. Environmental Protection Agency's technical protocol (EPA, 1998) and directives (EPA, 1999) on Monitored Natural Attenuation (MNA) as the foundation on which to introduce supporting concepts and new scientific developments that will support remediation of chlorinated solvents based on natural attenuation processes. This project supports the direction in which many site owners want to move to complete the remediation of their site(s), that being to complete the active treatment portion of the remedial effort and transition into MNA. The overarching objective of the effort was to examine environmental remedies that are based on natural processes--remedies such as Monitored Natural Attenuation (MNA) or Enhanced Attenuation (EA). The research program did identify several specific opportunities for advances based on: (1) mass balance as the central framework for attenuation based remedies, (2) scientific advancements and achievements during the past ten years, (3) regulatory and policy development and real-world experience using MNA, and (4) exploration of various ideas for integrating attenuation remedies into a systematic set of ''combined remedies'' for contaminated sites. These opportunities are summarized herein and are addressed in more detail in referenced project documents and

  3. Efficient inverted organic light-emitting devices by amine-based solvent treatment (Presentation Recording)

    Science.gov (United States)

    Song, Myoung Hoon; Choi, Kyoung-Jin; Jung, Eui Dae

    2015-10-01

    The efficiency of inverted polymer light-emitting diodes (iPLEDs) were remarkably enhanced by introducing spontaneously formed ripple-shaped nanostructure of ZnO (ZnO-R) and amine-based polar solvent treatment using 2-methoxyethanol and ethanolamine (2-ME+EA) co-solvents on ZnO-R. The ripple-shape nanostructure of ZnO layer fabricated by solution process with optimal rate of annealing temperature improves the extraction of wave guide modes inside the device structure, and 2-ME+EA interlayer enhances the electron injection and hole blocking and reduces exciton quenching between polar solvent treated ZnO-R and emissive layer. As a result, our optimized iPLEDs show the luminous efficiency (LE) of 61.6 cd A-1, power efficiency (PE) of 19.4 lm W-1 and external quantum efficiency (EQE) of 17.8 %. This method provides a promising method, and opens new possibilities for not only organic light-emitting diodes (OLEDs) but also other organic optoelectronic devices such as organic photovoltaics, organic thin film transistors, and electrically driven organic diode laser.

  4. Tools for identifying gelator scaffolds and solvents.

    Science.gov (United States)

    Zurcher, Danielle M; McNeil, Anne J

    2015-03-06

    Small molecule gelators are serendipitously discovered more often than they are designed. As a consequence, it has been challenging to develop applications based on the limited set of known materials. This synopsis highlights recent strategies to streamline the process of gelator discovery, with a focus on the role of unidirectional intermolecular interactions and solvation. We present these strategies as a series of tools that can be employed to help identify gelator scaffolds and solvents for gel formation. Overall, we suggest that this guided approach is more efficient than random derivatization and screening.

  5. SOLVENT EXTRACTION PROCESS FOR URANIUM RECOVERY

    Science.gov (United States)

    Clark, H.M.; Duffey, D.

    1958-06-17

    A process is described for extracting uranium from uranium ore, wherein the uranium is substantially free from molybdenum contamination. In a solvent extraction process for recovering uranium, uranium and molybdenum ions are extracted from the ore with ether under high acidity conditions. The ether phase is then stripped with water at a lower controiled acidity, resaturated with salting materials such as sodium nitrate, and reextracted with the separation of the molybdenum from the uranium without interference from other metals that have been previously extracted.

  6. Enhanced performance of dicationic ionic liquid electrolytes by organic solvents.

    Science.gov (United States)

    Li, Song; Zhang, Pengfei; Fulvio Pasquale, F; Hillesheim Patrick, C; Feng, Guang; Dai, Sheng; Cummings Peter, T

    2014-07-16

    The use of dicationic ionic liquid (DIL) electrolytes in supercapacitors is impeded by the slow dynamics of DILs, whereas the addition of organic solvents into DIL electrolytes improves ion transport and then enhances the power density of supercapacitors. In this work, the influences of organic solvents on the conductivity of DILs and the electrical double layer (EDL) of DIL-based supercapacitors are investigated using classical molecular dynamics simulation. Two types of organic solvents, acetonitrile (ACN) and propylene carbonate (PC), were used to explore the effects of different organic solvents on the EDL structure and capacitance of DIL/organic solvent-based supercapacitors. Firstly, it was found that the conductivity of DIL electrolytes was greatly enhanced in the presence of the organic solvent ACN. Secondly, a stronger adsorption of PC on graphite results in different EDL structures formed by DIL/ACN and DIL/PC electrolytes. The expulsion of co-ions from EDLs was observed in DIL/organic solvent electrolytes rather than neat DILs and this feature is more evident in DIL/PC. Furthermore, the bell-shaped differential capacitance-electric potential curve was not essentially changed by the presence of organic solvents. Comparing DIL/organic solvent electrolytes with neat DILs, the capacitance is slightly increased by organic solvents, which is in agreement with experimental observation.

  7. Solvents, Ethanol, Car Crashes and Tolerance: How Risky is Inhalation of Organic Solvents?

    Science.gov (United States)

    A research program in the National Health and Environmental Effects Research Laboratory of the U.S. EPA has led to some surprising considerations regarding the potential hazard of exposure to low concentrations of solvent vapors. This program involved conducting experiments to ch...

  8. Influence of solvent on the morphology and microstructure of YSZ films obtained by spray pyrolysis technique; Influencia do solvente na morfologia e microestrutura de filmes de YSZ obtidos pela tecnica spray pirolise

    Energy Technology Data Exchange (ETDEWEB)

    Falcade, T.; Oliveira, G.B.; Mueller, I.L.; Malfatti, C.F., E-mail: tiagocoti@gmail.co, E-mail: celia.malfatti@ufrgs.b [Universidade Federal do Rio Grande do Sul (LAPEC/PPGEM/UFRGS), Porto Alegre, RS (Brazil). Programa de Pos-graduacao em Engenharia de Minas. Lab. de Pesquisa em Corrosao; Tarrago, D.P.; Sousa, V.C.; Bergmann, C.P. [Universidade Federal do Rio Grande do Sul (PPGEM/UFRGS), Porto Alegre, RS (Brazil). Programa de Pos-graduacao em Engenharia de Minas; Souza, M.M.V.M. [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil)

    2010-07-01

    This work aims to investigate the influence of solvent used for the deposition of thin films of yttria stabilized zirconia (YSZ) on porous substrate. The films were obtained directly on the porous LSM substrate by spray pyrolysis technique, which consists of spraying a precursor solution containing salts of zirconium (Zr (C{sub 6}H{sub 7}O{sub 2}) 4) and yttrium (YCl{sub 3}.6H{sub 2}O), dissolved in specific solvents, on the heated substrate. The use of solvents with different boiling points and viscosity aims the optimization of experimental operating parameters to obtain homogeneous and dense films suitable for application as electrolyte in fuel cells, solid oxide (SOFC). The films were characterized by scanning electron microscopy, infrared spectroscopy and X-ray diffraction. (author)

  9. Solvent viscosity dependence for enzymatic reactions

    CERN Document Server

    Sitnitsky, A E

    2008-01-01

    A mechanism for relationship of solvent viscosity with reaction rate constant at enzyme action is suggested. It is based on fluctuations of electric field in enzyme active site produced by thermally equilibrium rocking (cranckshaft motion) of the rigid plane (in which the dipole moment $\\approx 3.6 D$ lies) of a favourably located and oriented peptide group (or may be a few of them). Thus the rocking of the plane leads to fluctuations of the electric field of the dipole moment. These fluctuations can interact with the reaction coordinate because the latter in its turn has transition dipole moment due to separation of charges at movement of the reacting system along it. The rocking of the plane of the peptide group is sensitive to the microviscosity of its environment in protein interior and the latter is a function of the solvent viscosity. Thus we obtain an additional factor of interrelationship for these characteristics with the reaction rate constant. We argue that due to the properties of the cranckshaft ...

  10. Non-Ideal Behavior in Solvent Extraction

    Energy Technology Data Exchange (ETDEWEB)

    Peter Zalupski

    2011-09-01

    This report presents a summary of the work performed to meet FCR&D level 3 milestone M31SW050801, 'Complete the year-end report summarizing FY11 experimental and modeling activities.' This work was carried out under the auspices of the Non-Ideality in Solvent Extraction Systems FCR&D work package. The report summarizes our initial considerations of potential influences that non-ideal chemistry may impose on computational prediction of outcomes in solvent extraction systems. The report is packaged into three separate test cases where a robustness of the prediction by SXFIT program is under scrutiny. The computational exercises presented here emphasize the importance of accurate representation of both an aqueous and organic mixtures when modeling liquid-liquid distribution systems. Case No.1 demonstrates that non-ideal behavior of HDEHP in aliphatic diluents, such as n-dodecane, interferes with the computation. Cases No.2 and No.3 focus on the chemical complexity of aqueous electrolyte mixtures. Both exercises stress the need for an improved thermodynamic model of an aqueous environment present in the europium distribution experiments. Our efforts for year 2 of this project will focus on the improvements of aqueous and non-aqueous solution models using fundamental physical properties of mixtures acquired experimentally in our laboratories.

  11. Analysis of solvent dyes in refined petroleum products by electrospray ionization mass spectrometry

    Science.gov (United States)

    Rostad, C.E.

    2010-01-01

    Solvent dyes are used to color refined petroleum products to enable differentiation between gasoline, diesel, and jet fuels. Analysis for these dyes in the hydrocarbon product is difficult due to their very low concentrations in such a complex matrix. Flow injection analysis/electrospray ionization/mass spectrometry in both negative and positive mode was used to optimize ionization of ten typical solvent dyes. Samples of hydrocarbon product were analyzed under similar conditions. Positive electrospray ionization produced very complex spectra, which were not suitably specific for targeting only the dyes. Negative electrospray ionization produced simple spectra because aliphatic and aromatic moieties were not ionized. This enabled screening for a target dye in samples of hydrocarbon product from a spill.

  12. Molecular Dynamics Simulations of a Flexible Polyethylene: A Protein-Like Behaviour in a Water Solvent

    CERN Document Server

    Kretov, D A

    2005-01-01

    We used molecular dynamics (MD) simulations to study the density and the temperature behaviour of a flexible polyethylene (PE) subjected to various heating conditions and to investigate the PE chain conformational changes in a water solvent. First, we have considered the influence of the heating process on the final state of the polymeric system and the sensitivity of its thermodynamic characteristics (density, energy, etc.) for different heating regimes. For this purpose three different simulations were performed: fast, moderate, and slow heating. Second, we have investigated the PE chain conformational dynamics in water solvent for various simulation conditions and various configurations of the environment. From the obtained results we have got the pictures of the PE dynamical motions in water. We have observed a protein-like behaviour of the PE chain, like that of the DNA and the proteins in water, and have also estimated the rates of the conformational changes. For the MD simulations we used the optimized...

  13. A green deep eutectic solvent-based aqueous two-phase system for protein extracting

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Kaijia; Wang, Yuzhi, E-mail: wyzss@hnu.edu.cn; Huang, Yanhua; Li, Na; Wen, Qian

    2015-03-15

    Highlights: • A strategy for the protein purification with a deep eutectic solvent(DES)-based aqueous two-phase system. • Choline chloride-glycerin DES was selected as the extraction solvent. • Bovine serum albumin and trypsin were used as the analytes. • Aggregation phenomenon was detected in the mechanism research. - Abstract: As a new type of green solvent, deep eutectic solvent (DES) has been applied for the extraction of proteins with an aqueous two-phase system (ATPS) in this work. Four kinds of choline chloride (ChCl)-based DESs were synthesized to extract bovine serum albumin (BSA), and ChCl-glycerol was selected as the suitable extraction solvent. Single factor experiments have been done to investigate the effects of the extraction process, including the amount of DES, the concentration of salt, the mass of protein, the shaking time, the temperature and PH value. Experimental results show 98.16% of the BSA could be extracted into the DES-rich phase in a single-step extraction under the optimized conditions. A high extraction efficiency of 94.36% was achieved, while the conditions were applied to the extraction of trypsin (Try). Precision, repeatability and stability experiments were studied and the relative standard deviations (RSD) of the extraction efficiency were 0.4246% (n = 3), 1.6057% (n = 3) and 1.6132% (n = 3), respectively. Conformation of BSA was not changed during the extraction process according to the investigation of UV–vis spectra, FT-IR spectra and CD spectra of BSA. The conductivity, dynamic light scattering (DLS) and transmission electron microscopy (TEM) were used to explore the mechanism of the extraction. It turned out that the formation of DES–protein aggregates play a significant role in the separation process. All the results suggest that ChCl-based DES-ATPS are supposed to have the potential to provide new possibilities in the separation of proteins.

  14. Influences of Restaurant Waste Fats and Oils (RWFO from Grease Trap as Binder on Rheological and Solvent Extraction Behavior in SS316L Metal Injection Molding

    Directory of Open Access Journals (Sweden)

    Mohd Halim Irwan Ibrahim

    2016-02-01

    Full Text Available This article deals with rheological and solvent extraction behavior of stainless steel 316L feedstocks using Restaurant Waste Fats and Oils (RWFO from grease traps as binder components along with Polypropylene (PP copolymer as a backbone binder. Optimal binder formulation and effect of solvent extraction variables on green compacts are being analyzed. Four binder formulations based on volumetric ratio/weight fraction between PP and RWFO being mixed with 60% volumetric powder loading of SS316L powder each as feedstock. The rheological analysis are based on viscosity, shear rate, temperature, activation energy, flow behavior index, and moldability index. The optimal feedstock formulation will be injected to form green compact to undergo the solvent extraction process. Solvent extraction variables are based on solvent temperature which are 40 °C, 50 °C, and 60 °C with different organic solvents of n-hexane and n-heptane. Analysis of the weight loss percentage and diffusion coefficient is done on the green compact during the solvent extraction process. Differential Scanning Calorimeter (DSC is used to confirm the extraction of the RWFO in green compacts. It is found that all binder fractions exhibit pseudoplastic behavior or shear thinning where the viscosity decreases with increasing shear rate. After considering the factors that affect the rheological characteristic of the binder formulation, feedstock with binder formulation of 20/20 volumetric ratio between PP and RWFO rise as the optimal binder. It is found that the n-hexane solvent requires less time for extracting the RWFO at the temperature of 60 °C as proved by its diffusion coefficient.

  15. Autoclave nuclear criticality safety analysis

    Energy Technology Data Exchange (ETDEWEB)

    D`Aquila, D.M. [Martin Marietta Energy Systems, Inc., Piketon, OH (United States); Tayloe, R.W. Jr. [Battelle, Columbus, OH (United States)

    1991-12-31

    Steam-heated autoclaves are used in gaseous diffusion uranium enrichment plants to heat large cylinders of UF{sub 6}. Nuclear criticality safety for these autoclaves is evaluated. To enhance criticality safety, systems are incorporated into the design of autoclaves to limit the amount of water present. These safety systems also increase the likelihood that any UF{sub 6} inadvertently released from a cylinder into an autoclave is not released to the environment. Up to 140 pounds of water can be held up in large autoclaves. This mass of water is sufficient to support a nuclear criticality when optimally combined with 125 pounds of UF{sub 6} enriched to 5 percent U{sup 235}. However, water in autoclaves is widely dispersed as condensed droplets and vapor, and is extremely unlikely to form a critical configuration with released UF{sub 6}.

  16. UV-Vis spectroscopic study and DFT calculation on the solvent effect of trimethoprim in neat solvents and aqueous mixtures

    Science.gov (United States)

    Almandoz, M. C.; Sancho, M. I.; Duchowicz, P. R.; Blanco, S. E.

    2014-08-01

    The solvatochromic behavior of trimethoprim (TMP) was analyzed using UV-Vis spectroscopy and DFT methods in neat and binary aqueous solvent mixtures. The effects of solvent dipolarity/polarizability and solvent-solute hydrogen bonding interactions on the absorption maxima were evaluated by means of the linear solvation energy relationship concept of Kamlet and Taft. This analysis indicated that both interactions play an important role in the position of the absorption maxima in neat solvents. The simulated absorption spectra of TMP and TMP:(solvent)n complexes in ACN and H2O using TD-DFT methods were in agreement with the experimental ones. Binary aqueous mixtures containing as co-solvents DMSO, ACN and EtOH were studied. Preferential solvation was detected as a nonideal behavior of the wavenumber curve respective to the analytical mole fraction of co-solvent in all binary systems. TMP molecules were preferentially solvated by the organic solvent over the whole composition range. Index of preferential solvation, as well as the influence of solvent parameters were calculated as a function of solvent composition.

  17. UV-Vis spectroscopic study and DFT calculation on the solvent effect of trimethoprim in neat solvents and aqueous mixtures.

    Science.gov (United States)

    Almandoz, M C; Sancho, M I; Duchowicz, P R; Blanco, S E

    2014-08-14

    The solvatochromic behavior of trimethoprim (TMP) was analyzed using UV-Vis spectroscopy and DFT methods in neat and binary aqueous solvent mixtures. The effects of solvent dipolarity/polarizability and solvent-solute hydrogen bonding interactions on the absorption maxima were evaluated by means of the linear solvation energy relationship concept of Kamlet and Taft. This analysis indicated that both interactions play an important role in the position of the absorption maxima in neat solvents. The simulated absorption spectra of TMP and TMP:(solvent)n complexes in ACN and H2O using TD-DFT methods were in agreement with the experimental ones. Binary aqueous mixtures containing as co-solvents DMSO, ACN and EtOH were studied. Preferential solvation was detected as a nonideal behavior of the wavenumber curve respective to the analytical mole fraction of co-solvent in all binary systems. TMP molecules were preferentially solvated by the organic solvent over the whole composition range. Index of preferential solvation, as well as the influence of solvent parameters were calculated as a function of solvent composition. Copyright © 2014 Elsevier B.V. All rights reserved.

  18. Stochastic level-set variational implicit-solvent approach to solute-solvent interfacial fluctuations

    Science.gov (United States)

    Zhou, Shenggao; Sun, Hui; Cheng, Li-Tien; Dzubiella, Joachim; McCammon, J. Andrew

    2016-01-01

    Recent years have seen the initial success of a variational implicit-solvent model (VISM), implemented with a robust level-set method, in capturing efficiently different hydration states and providing quantitatively good estimation of solvation free energies of biomolecules. The level-set minimization of the VISM solvation free-energy functional of all possible solute-solvent interfaces or dielectric boundaries predicts an equilibrium biomolecular conformation that is often close to an initial guess. In this work, we develop a theory in the form of Langevin geometrical flow to incorporate solute-solvent interfacial fluctuations into the VISM. Such fluctuations are crucial to biomolecular conformational changes and binding process. We also develop a stochastic level-set method to numerically implement such a theory. We describe the interfacial fluctuation through the “normal velocity” that is the solute-solvent interfacial force, derive the corresponding stochastic level-set equation in the sense of Stratonovich so that the surface representation is independent of the choice of implicit function, and develop numerical techniques for solving such an equation and processing the numerical data. We apply our computational method to study the dewetting transition in the system of two hydrophobic plates and a hydrophobic cavity of a synthetic host molecule cucurbit[7]uril. Numerical simulations demonstrate that our approach can describe an underlying system jumping out of a local minimum of the free-energy functional and can capture dewetting transitions of hydrophobic systems. In the case of two hydrophobic plates, we find that the wavelength of interfacial fluctuations has a strong influence to the dewetting transition. In addition, we find that the estimated energy barrier of the dewetting transition scales quadratically with the inter-plate distance, agreeing well with existing studies of molecular dynamics simulations. Our work is a first step toward the

  19. The Reactivity of HNOx Species in Solvent-Free, Aqueous Media and Biological Systems

    Science.gov (United States)

    Francisco, Joseph S.; Dixon, David A.; Feller, David; Zhan, Chang-Guo

    2002-03-01

    The hydronitrogen oxides (HNO_x) have important and different chemical functions in aqueous media under biological conditions. HNO can act as a potent cytotoxic agent that causes double-stranded breaks in DNA. It has been proposed that peroxynitrous acid (HOONO), which forms after protonation of the peroxynitrite ion (ONOO^-), a potent oxidant of biomolecules. We report results of fundamental chemical and energetic properties of HNOx (x = 1-3) in solvent-free (gas phase) and in aqueous solvent environments. It is critical to get the gas phase properties for these molecules correct before evaluating solution corrections. These data are used to evaluate the reactivity toward biomolecules. New possibilities for the involvement of nitroxyl and peroxynitrite will be discussed.

  20. Solubility of gases and solvents in silicon polymers: molecular simulation and equation of state modeling

    DEFF Research Database (Denmark)

    Economou, Ioannis; Makrodimitri, Zoi A.; Kontogeorgis, Georgios

    2007-01-01

    The solubility of n-alkanes, perfluoroalkanes, noble gases and light gases in four elastomer polymers containing silicon is examined based on molecular simulation and macroscopic equation of state modelling. Polymer melt samples generated from molecular dynamics ( MD) are used for the calculation...... of gas and solvent solubilities using the test particle insertion method of Widom. Polymer chains are modelled using recently developed realistic atomistic force fields. Calculations are performed at various temperatures and ambient pressure. A crossover in the temperature dependence of solubility...... as a function of the gas/solvent critical temperature is observed for all polymers. A macroscopic model based on the simplified perturbed chain-statistical associating fluid theory ( sPC-SAFT) is used for the prediction and correlation of solubilities in poly( dimethylsilamethylene) and poly( dimethylsiloxane...

  1. Investigating Solvent Purity Utilizing Comprehensive Gas Chromatography: A Study of Acetones

    Energy Technology Data Exchange (ETDEWEB)

    Wahl, Jon H.; Bolz, Cinnamon DH; Wahl, Karen L.

    2010-04-01

    Broad spectrum chemical analysis of trace level components is a continuing challenge for any analytical chemist. This challenge is further confounded when chemical impurities may be present in common organic solvents or when chemical artifacts may be formed, produced and introduced during an analytical procedure. Minimizing and understanding these chemical artifacts, is critical for trace level detection and is crucial for unambiguous analytical results. Comprehensive gas chromatography is an excellent analytical tool to help address these complex mixture challenges. This work examines the impurities present in various acetone sources utilizing comprehensive gas chromatography. This work highlights the extreme variability possible in solvent sources and hence the importance of understanding the impurities that may confound an analytical method or result.

  2. Isolation, identification and characterization of organic solvent tolerant protease from Bacillus sp. DAF-01

    Directory of Open Access Journals (Sweden)

    Arastoo Badoei-Dalfard

    2012-01-01

    Full Text Available Introduction: Organic solvent-tolerant bacteria are relatively novel extermophilic microorganisms, which can produce organic tolerant protease with capacity of being used in industrial biotechnology for producing high-value compounds. Therefore, finding of these bacteria has drawn much researchers attention nowadays. Materials and Methods: In this project, samples were collected from a hot spring, located in Jiroft. Samples were incubated in medium supplemented with cyclohexane and toluene for 3 days. Screening of protease producing bacteria was performed on the specific media, SKM (Skim milk agar, based on clear area diameter. The best bacterium was identified based on 16s rDNA gene. Protease activity was considered in different temperatures, pH and organic solvents.Results: Sequence alignment and phylogenetic tree results showed that this bacteria was closely related to Bacillus niacini, with 97% homology. Enzymatic studies showed that, this enzyme was active at a wide range of temperatures, 20-90 °C and it,s optimal activity was in 60 °C. In addition, maximum protease activity was obtained in the 8-9 range of pH, and optimal stability was also at pH 9.0. Protease activity in the presence of methanol, toluene, isopropanol, cyclohexane and DMF ‏showed that, remaining activity was at least 80% compared to the control (without organic solvent Discussion and Conclusion: Thermopilic capacity, being active in alkaline protease and high protease stability in the presence of organic solvents all herald a remarkable application for using in different industries.

  3. Measurement of oxygen transfer from air into organic solvents

    DEFF Research Database (Denmark)

    Ramesh, Hemalata; Mayr, Torsten; Hobisch, Mathias

    2016-01-01

    biological reactions require the supply of oxygen, most normally from air. However, reliable on-line measurements of oxygen concentration in organic solvents (and hence oxygen transfer rates from air to the solvent) has to date proven impossible due limitations in the current analytical methods. Results...... For the first time, we demonstrate on-line oxygen measurements in non-aqueous media using a novel optical sensor. The sensor was used to measure oxygen concentration in various organic solvents including toluene, THF, isooctane, DMF, heptane and hexane (which have all been shown suitable for several biological...... applications). Subsequently, we measured the oxygen transfer rates from air into these organic solvents. Conclusion The measurement of oxygen transfer rates from air into organic solvents using the dynamic method was established using the solvent resistant optical sensor. The feasibility of online oxygen...

  4. Acid gas scrubbing by composite solvent-swollen membranes

    Science.gov (United States)

    Matson, Stephen L.; Lee, Eric K. L.; Friesen, Dwayne T.; Kelly, Donald J.

    1988-01-01

    A composite immobilized liquid membrane suitable for acid gas scrubbing is disclosed. The membrane is a solvent-swollen polymer and a microporous polymeric support, the solvent being selected from a class of highly polar solvents containing at least one atom selected from nitrogen, oxygen, phosphorous and sulfur, and having a boiling point of at least 100.degree. C. and a solubility parameter of from about 7.5 to about 13.5 (cal/cm.sup.3 -atm).sup.1/2. Such solvents are homogeneously distributed through the solvent-swollen polymer from 20% to 95% by weight. Also disclosed are methods of acid gas scrubbing of high- and low-Btu gas effluents with such solvent-swollen membranes.

  5. Thermodynamic method for obtaining the solubilities of complex medium-sized chemicals in pure and mixed solvents

    DEFF Research Database (Denmark)

    Abildskov, Jens; O'Connell, J.P.

    2005-01-01

    This paper extends our previous simplified approach to using group contribution methods and limited data to determine differences in solubility of sparingly soluble complex chemicals as the solvent is changed. New applications include estimating temperature dependence and the effect of adding...... cosolvents forming strongly nonideal aqueous mixtures and including immiscibility. The method optimally selects a 'reference solvent' from limited data, which effectively eliminates the need for pure-solute properties and minimizes the impact of their uncertainties. The technique also decreases the number....... Though we present no new solution theory, the paper shows an especially efficient use of thermodynamic models for solvent and cosolvent selection for product formulations. Examples and discussion of applications are given. (c) 2004 Elsevier B.V. All rights reserved....

  6. Exploiting sequential injection on-line solvent extraction/back extraction with detection by ETAAS and ICPMS

    DEFF Research Database (Denmark)

    Wang, Jianhua; Hansen, Elo Harald

    . With detection by ETAAS, separation/preconcentration by solvent extraction has enjoyed much use. However, this approach is not necessarily the optimal one since introduction of organic eluates directly into the graphite tube might lead to deteriorated reproducibility and lower sensitivity. And for ICPMS......, organics are prohibitive because they give rise to an unstable plasma, and excessive carbon deposited on the sampling and skimmer cones might result in a gradual loss of sensitivity. All of these difficulties can be readily overcome by using solvent extraction/back extraction. Surprisingly, this approach...... presents an on-line SI-solvent extraction/back extraction procedure used in connection with detection by either ETAAS or ICPMS. Incorporating two newly designed dual-conical gravitational phase separators, its performance is demonstrated for the determination of various metals in reference materials....

  7. Exploiting Sequential Injection on-line Solvent Extraction/Back Extraction with Detection by ETAAS or ICPMS

    DEFF Research Database (Denmark)

    Wang, Jianhua; Hansen, Elo Harald

    tolerances. With detection by ETAAS, separation/preconcentration by solvent extraction has enjoyed much use. However, this approach is not necessarily the optimal one since introduction of organic eluates directly into the graphite tube might lead to deteriorated reproducibility and lower sensitivity....... And for ICPMS, organics are prohibitive because they give rise to an unstable plasma, and excessive carbon deposited on the sampling and skimmer cones might result in a gradual loss of sensitivity. All of these difficulties can be readily overcome by using solvent extraction/back extraction. Surprisingly...... presents an on-line SI-solvent extraction/back extraction procedure used in connection with detection by either ETAAS or ICPMS. Incorporating two newly designed dual-conical gravitational phase separators, its performance is demonstrated for the determination of various metals in reference materials....

  8. Effect of Solvents on Stabiliziation of Micro Drug Particles

    Energy Technology Data Exchange (ETDEWEB)

    C Desai; X Meng; D Yang; X Wang; V Akkunuru; S Mitra

    2011-12-31

    Antisolvent synthesis of micron scale Griseofulvin was carried out with simultaneous suspension stabilization under low power ultrasonic agitation. The organic solvent plays an important role because the supersaturation could be varied by using different solvents and the physicochemical characteristics of the suspension are also altered, which affects stability. In this study we present the effect of solvents on particle formation, polymorphism and stability of micron scale Griseofulvin formation in aqueous media.

  9. Effect of solvents on stabilization of micro drug particles

    Science.gov (United States)

    Desai, Chintal; Meng, Xiangxin; Yang, Dachuan; Wang, Xianqin; Akkunuru, Vamshi; Mitra, Somenath

    2011-01-01

    Antisolvent synthesis of micron scale Griseofulvin was carried out with simultaneous suspension stabilization under low power ultrasonic agitation. The organic solvent plays an important role because the supersaturation could be varied by using different solvents and the physicochemical characteristics of the suspension are also altered, which affects stability. In this study we present the effect of solvents on particle formation, polymorphism and stability of micron scale Griseofulvin formation in aqueous media.

  10. Effect of Organic Solvent on the Enzyme Bleaching Agent System

    OpenAIRE

    コマツ, エミコ; モリタ, ミユキ; Emiko, KOMATSU; Miyuki, MORITA

    2002-01-01

    The Orange n decoloration reaction in the presence of various organic solvents with the HRP-H_2O_2 system was examined. In 5% organic solvent mixing aqueous solutions, the decoloration rates of Orange n were about 0.9-0.5 times of those in the aqueous solutions. Decoloration rate of Orange II decreased, as the concentration of organic solvent increases. The reaction of Orange n decoloration stopped at the 60% dimethyl sulfoxide concentration.

  11. Solvent effects on enzymes - Implications for extraterrestrial life.

    Science.gov (United States)

    Heinrich, M. R.

    1972-01-01

    Review of several studies on the alterations taking place in the structure, catalytic activity, specificity, and stability of an enzyme when some or all of the water in the medium is replaced by another solvent. These studies show the utility of solvents as a tool for probing enzyme function. They also suggest that solvents other than water should be investigated as media for controlling and directing enzyme reactions.

  12. Ultrasound induced green solvent extraction of oil from oleaginous seeds.

    Science.gov (United States)

    Sicaire, Anne-Gaëlle; Vian, Maryline Abert; Fine, Frédéric; Carré, Patrick; Tostain, Sylvain; Chemat, Farid

    2016-07-01

    Ultrasound-assisted extraction of rapeseed oil was investigated and compared with conventional extraction for energy efficiency, throughput time, extraction yield, cleanness, processing cost and product quality. A multivariate study enabled us to define optimal parameters (7.7 W/cm(2) for ultrasonic power intensity, 40 °C for processing temperature, and a solid/liquid ratio of 1/15) for ultrasound-assisted extraction of oil from oilseeds to maximize lipid yield while reducing solvent consumption and extraction time using response surface methodology (RSM) with a three-variable central composite design (CCD). A significant difference in oil quality was noted under the conditions of the initial ultrasound extraction, which was later avoided using ultrasound in the absence of oxygen. Three concepts of multistage cross-current extraction were investigated and compared: conventional multistage maceration, ultrasound-assisted maceration and a combination, to assess the positive impact of using ultrasound on the seed oil extraction process. The study concludes that ultrasound-assisted extraction of oil is likely to reduce both economic and ecological impacts of the process in the fat and oil industry. Copyright © 2016 Elsevier B.V. All rights reserved.

  13. Determination of atorvastatin in human serum by salting out assisted solvent extraction and reversed-phase high-performance liquid chromatography–UV detection

    OpenAIRE

    Jalal Hassan; Seyed Hamid Bahrani

    2014-01-01

    A simple and rapid technique based on salting out assisted solvent extraction was developed for extraction of atorvastatin from serum sample and high performance liquid chromatography–UV was used for its detection. In the present study, 1.0 mL serum was extracted by 0.5 mL of acetonitrile and some parameters that can affect extraction such as type and volume of extraction solvent, type of salt, and pH were optimized. Under optimized experimental conditions, the calibration curve was found to ...

  14. Pro Android Apps Performance Optimization

    CERN Document Server

    Guihot, Hervé

    2012-01-01

    Today's Android apps developers are often running into the need to refine, improve and optimize their apps performances. As more complex apps can be created, it is even more important for developers to deal with this critical issue. Android allows developers to write apps using Java, C or a combination of both with the Android SDK and the Android NDK. Pro Android Apps Performance Optimization reveals how to fine-tune your Android apps, making them more stable and faster. In this book, you'll learn the following: * How to optimize your Java code with the SDK, but also how to write and optimize

  15. Poly(ethylene glycol)-based ionic liquids: properties and uses as alternative solvents in organic synthesis and catalysis.

    Science.gov (United States)

    Cecchini, Martina Maya; Charnay, Clarence; De Angelis, Francesco; Lamaty, Frédéric; Martinez, Jean; Colacino, Evelina

    2014-01-01

    PEG-based ionic liquids are a new appealing group of solvents making the link between two distinct but very similar fluids: ionic liquids and poly(ethylene glycol)s. They find applications across a range of innumerable disciplines in science, technology, and engineering. In the last years, the possibility to use these as alternative solvents for organic synthesis and catalysis has been increasingly explored. This Review highlights strategies for their synthesis, their physical properties (critical point, glass transition temperature, density, rheological properties), and their application in reactions catalyzed by metals (such as Pd, Cu, W, or Rh) or as organic solvent (for example for multicomponent reactions, organocatalysis, CO2 transformation) with special emphasis on their toxicity, environmental impact, and biodegradability. These aspects, very often neglected, need to be considered in addition to the green criteria usually considered to establish ecofriendly processes. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Antimicrobial potentials of different solvent extracted samples from Physalis ixocarpa

    National Research Council Canada - National Science Library

    Khan, Wajid; Bakht, Jehan; Shafi, Mohammad

    2016-01-01

    The present study investigates the antimicrobial activities of different solvent extracted samples isolated from different parts of Physalis ixocarpa through disc diffusion assay using three different concentrations...

  17. A simple solvent collection technique for a dispersive liquid-liquid microextraction of parabens from aqueous samples using low-density organic solvent.

    Science.gov (United States)

    Cabuk, Hasan; Akyüz, Mehmet; Ata, Sevket

    2012-10-01

    A simple technique for the collection of an extraction solvent lighter than water after dispersive liquid-liquid microextraction combined with high-performance liquid chromatography with ultraviolet detection was developed for the determination of four paraben preservatives in aqueous samples. After the extraction procedure, low-density organic solvent together with some little aqueous phase was separated by using a disposable glass Pasteur pipette. Next, the flow of the aqueous phase was stopped by successive dipping the capillary tip of the pipette into anhydrous Na(2)SO(4). The upper organic layer was then removed simply with a microsyringe and injected into the high-performance liquid chromatography system. Experimental parameters that affect the extraction efficiency were investigated and optimized. Under optimal extraction conditions, the extraction recoveries ranged from 25 to 86%. Good linearity with coefficients with the square of correlation coefficients ranging from 0.9984 to 0.9998 was observed in the concentration range of 0.001-0.5 μg/mL. The relative standard deviations ranged from 4.1 to 9.3% (n = 5) for all compounds. The limits of detection ranged from 0.021 to 0.046 ng/mL. The method was successfully applied for the determination of parabens in tap water and fruit juice samples and good recoveries (61-108%) were achieved for spiked samples. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Introduction to Nonlinear and Global Optimization

    NARCIS (Netherlands)

    Hendrix, E.M.T.; Tóth, B.

    2010-01-01

    This self-contained text provides a solid introduction to global and nonlinear optimization, providing students of mathematics and interdisciplinary sciences with a strong foundation in applied optimization techniques. The book offers a unique hands-on and critical approach to applied optimization

  19. Website Optimization

    CERN Document Server

    King, Andrew

    2008-01-01

    Remember when an optimized website was one that merely didn't take all day to appear? Times have changed. Today, website optimization can spell the difference between enterprise success and failure, and it takes a lot more know-how to achieve success. This book is a comprehensive guide to the tips, techniques, secrets, standards, and methods of website optimization. From increasing site traffic to maximizing leads, from revving up responsiveness to increasing navigability, from prospect retention to closing more sales, the world of 21st century website optimization is explored, exemplified a

  20. Critical Pedagogy for Critical Mathematics Education

    Science.gov (United States)

    Tutak, Fatma Aslan; Bondy, Elizabeth; Adams, Thomasenia L.

    2011-01-01

    This article provides a brief introduction to critical pedagogy and further discussion on critical mathematics education. Critical mathematics education enables students to read the world with mathematics. Three emerging domains of mathematics education related to critical mathematics education are discussed in this manuscript: ethnomathematics,…

  1. EXPLORING THE USEFULNESS OF KEY GREEN PHYSICOCHEMICAL PROPERTIES. QUANTITATIVE STRUCTURE ACTIVITY RELATIONSHIP (QSAR) FOR SOLVENTS FROM BIOMASS.

    Science.gov (United States)

    Zuriaga, Estefanía; Giner, Beatriz; Ribate, María Pilar; García, Cristina B; Lomba, Laura

    2017-12-13

    During the last decades there has been a growing interest in the development of new solvents from biomass. Some of these new solvents have been classified as green due to their renewable and sustainable source. However, characterization from the ecotoxicological and physicochemical point of view is needed in order to categorize them as green solvents. We have selected several key physicochemical properties that can reflect environmental features (density, boiling point, critical aggregation concentration and Log P) and explored their usefulness for preliminary assessing the green character of the studied solvents. Specifically, we have studied several solvents form biomass; lactate family (methyl, ethyl and butyl lactate), furfural family (furfural, 5-methylfurfural, furfuryl alcohol and tetrahydrofurfuryl alcohol) and levulinate family (methyl, ethyl and butyl levulinate). In order to fill the gaps and complete some toxicity data for the environment, we have measured the ecotoxicity using two of the most common and versatile biomodels; bacteria Vibrio fischeri and crustacean Daphnia magna for furfural and lactate derived compounds. Results indicate that solvents from biomass can be categorized as green since their toxicity for the environment is low. Finally, a QSAR study has been performed with the selected key properties and the ecotoxicological information. Despite the different structure of the chemicals under study, good correlations have been found for the studied organisms. It seems that the Log P and critical aggregation concentration (c.a.c.) carry the most part of the ecotoxic behaviour, while density and boiling point cannot reflect toxicity signals. However, these properties are rather useful for assessing the environmental final fate of the studied chemicals. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

  2. Solvent control of intramolecular proton transfer

    DEFF Research Database (Denmark)

    Manolova, Y.; Marciniak, Heinz; Tschierlei, S.

    2017-01-01

    The solvent dependent excited state dynamics of 4-hydroxy-3-(piperidin-1-ylmethyl)-1-naphthaldehyde (compound 2), a candidate for a molecular switch based on intramolecular proton transfer, was investigated by ultrafast spectroscopy and quantum-chemical calculations. In acetonitrile a mixture...... of molecules in the enol and zwitterionic proton transfer (PT) form exists in the ground state. However, the zwitterion is the energetically favored one in the electronically excited state. Optical excitation of the enol form results in intramolecular proton transfer and formation of the PT form within 1.4 ps....... In addition we observe the appearance of a long living species with a rate of 1/(330 ps) which returns to the original ground state on time scales beyond 2 ns and which is attributed to the triplet state. In toluene the enol form is the only observed ground state tautomer, but no light induced proton transfer...

  3. Is Water a Universal Solvent for Life?

    Science.gov (United States)

    Pohorill, Andrew

    2012-01-01

    There are strong reasons to believe that the laws, principles and constraints of physics and chemistry are universal. It is much less clear how this universality translates into our understanding of the origins of life. Conventionally, discussions of this topic focus on chemistry that must be sufficiently rich to seed life. Although this is clearly a prerequisite for the emergence of living systems, I propose to focus instead on self-organization of matter into functional structures capable of reproduction, evolution and responding to environmental changes. In biology, most essential functions are largely mediated by noncovalent interactions (interactions that do not involve making or breaking chemical bonds). Forming chemical bonds is only a small part of what living systems do. There are specific implications of this point of view for universality. I will concentrate on one of these implications. Strength of non-covalent interactions must be properly tuned. If they were too weak, the system would exhibit undesired, uncontrolled response to natural fluctuations of physical and chemical parameters. If they were too strong kinetics of biological processes would be slow and energetics costly. This balance, however, is not a natural property of complex chemical systems. Instead, it has to be achieved with the aid of an appropriate solvent for life. In particular, potential solvents for life must be characterized by a high dielectric constant to ensure solubility of polar species and sufficient flexibility of biological structures stabilized by electrostatic interactions. Among these solvents, water exhibits a remarkable trait that it also promotes solvophobic (hydrophobic) interactions between non-polar species, typically manifested by a tendency of these species to aggregate and minimize their contacts with the aqueous solvent. Hydrophobic interactions are responsible, at least in part, for many self-organization phenomena in biological systems, such as the formation

  4. Organogels thermodynamics, structure, solvent role, and properties

    CERN Document Server

    Guenet, Jean-Michel

    2016-01-01

    This book provides a physics-oriented introduction to organogels with a comparison to polymer thermoreversible gels whenever relevant. The past decade has seen the development of a wide variety of newly-synthesized molecules that can spontaneously self-assemble or crystallize from their organic or aqueous solutions to produce fibrillar networks, namely organogels, with potential applications in organic electronics, light harvesting, bio-imaging, non-linear optics, and the like. This compact volume presents a detailed outlook of these novel molecular systems with special emphasis upon their thermodynamics, morphology, molecular structure, and rheology. The definition of these complex systems is also tackled, as well as the role of the solvent. The text features numerous temperature-phase diagrams for a variety of organogels as well as illustrations of their structures at the microscopic, mesoscopic and macroscopic level. A review of some potential applications is provided including hybrid functional materials ...

  5. Optimization of extraction of β-endoglucanase from the fermented bran of Aspergillus niger

    OpenAIRE

    Chandra, M. Subhosh; Viswanath, Buddolla; Reddy, B. Rajasekhar

    2010-01-01

    A local isolate of Aspergillus niger was cultivated under optimal growth conditions on wheat bran in solid state fermentation. β-endoglucanase from fermented bran was separately extracted with different solvents to test recovery of enzyme. Among solvents tested, distilled water served the best leachate. Conditions were further optimized with this leachate. Two washes of fermented bran with the leachate for 30 min each under shaking conditions in a ratio of 1 g of wheat bran: 4 ml of distilled...

  6. Separation of polysaccharides from rice husk and wheat bran using solvent system consisting of BMIMOAc and DMI.

    Science.gov (United States)

    Hou, Qidong; Li, Weizun; Ju, Meiting; Liu, Le; Chen, Yu; Yang, Qian; Wang, Jingyu

    2015-11-20

    A solvent system consisting of 1,3-dimethyl-2-imidazolidinone (DMI), and ionic liquid 1-butyl-3-methylimidazolium acetate (BMIMOAc) was used to separate polysaccharides from rice husk and wheat bran. The effects of the DMI/BMIMOAc ratios, temperature, and time on the dissolution of rice husk and wheat bran were investigated, and the influence of anti-solvents on the regeneration of polysaccharides-rich material was evaluated. We found that the solvent system is more powerful to dissolve rice husk and wheat bran than pure BMIMOAc, and that polysaccharides-rich material can be effectively separated from the biomass solution. The polysaccharides content of regenerated material from wheat bran can reach as high as 94.4% when ethanol was used as anti-solvents. Under optimized conditions, the extraction rate of polysaccharides for wheat bran can reach as high as 71.8% at merely 50°C. The recycled solvent system exhibited constant ability to separate polysaccharides from rice husk and wheat bran. Copyright © 2015 Elsevier Ltd. All rights reserved.

  7. Continuous two stage acetone-butanol-ethanol fermentation with integrated solvent removal using Clostridium acetobutylicum B 5313.

    Science.gov (United States)

    Bankar, Sandip B; Survase, Shrikant A; Singhal, Rekha S; Granström, Tom

    2012-02-01

    The objective of this study was to optimize continuous acetone-butanol-ethanol (ABE) fermentation using a two stage chemostat system integrated with liquid-liquid extraction of solvents produced in the first stage. This minimized end product inhibition by butanol and subsequently enhanced glucose utilization and solvent production in continuous cultures of Clostridium acetobutylicum B 5313. During continuous two-stage ABE fermentation, sugarcane bagasse was used as the cell holding material for the both stages and liquid-liquid extraction was performed using an oleyl alcohol and decanol mixture. An overall solvent production of 25.32g/L (acetone 5.93g/L, butanol 16.90g/L and ethanol 2.48g/L) was observed as compared to 15.98g/L in the single stage chemostat with highest solvent productivity and solvent yield of 2.5g/Lh and of 0.35g/g, respectively. Maximum glucose utilization (83.21%) at a dilution rate of 0.051/h was observed as compared to 54.38% in the single stage chemostat. Copyright © 2011 Elsevier Ltd. All rights reserved.

  8. A novel and organic solvent-free preparation of solid lipid nanoparticles using natural biopolymers as emulsifier and stabilizer.

    Science.gov (United States)

    Xue, Jingyi; Wang, Taoran; Hu, Qiaobin; Zhou, Mingyong; Luo, Yangchao

    2017-10-05

    In this work, a new and novel organic solvent-free and synthetic surfactant-free method was reported to fabricate stable solid lipid nanoparticles (SLNs) from stearic acid, sodium caseinate (NaCas) and pectin, as well as water. Melted stearic acid was directly emulsified into an aqueous phase containing NaCas and pectin, followed by pH adjustment and thermal treatment to induce the formation of a compact and dense polymeric coating which stabilized SLNs. The preparation procedures and formulations were comprehensively optimized. The inter- and intra-molecular interactions among three ingredients were characterized by fluorescence and Fourier transform infrared spectroscopies. The stability of as-prepared SLNs was evaluated under simulated gastrointestinal conditions, and compared with traditional SLNs prepared with organic solvents. Our results revealed that the SLNs prepared from this organic solvent-free method had superior physicochemical properties over the traditional SLNs, including smaller size and better stability. Furthermore, redispersible SLNs powders were obtained by nano spray drying, but only the SLNs prepared by organic solvent-free method had sub-micron scale, uniform and spherical morphology. The organic solvent-free preparation method was proved to be a promising approach to prepare stable and uniform SLNs for potential oral delivery applications. Copyright © 2017 Elsevier B.V. All rights reserved.

  9. Extraction of bioactive compounds from sesame (Sesamum indicum L.) defatted seeds using water and ethanol under sub-critical conditions.

    Science.gov (United States)

    Bodoira, Romina; Velez, Alexis; Andreatta, Alfonsina E; Martínez, Marcela; Maestri, Damián

    2017-12-15

    Sesame seeds contain a vast array of lignans and phenolic compounds having important biological properties. An optimized method to obtain these seed components was designed by using water and ethanol at high pressure and temperature conditions. The maximum concentrations of lignans, total phenolics, flavonoids and flavonols compounds were achieved at 220°C extraction temperature and 8MPa pressure, using 63.5% ethanol as co-solvent. Under these conditions, the obtained sesame extracts gave the best radical scavenging capacity. Kinetic studies showed a high extraction rate of phenolic compounds until the first 50min of extraction, and it was in parallel with the highest scavenging capacity. The comparison of our results with those obtained under conventional extraction conditions (normal pressure, ambient temperature) suggests that recovery of sesame bioactive compounds may be markedly enhanced using water/ethanol mixtures at sub-critical conditions. Copyright © 2017 Elsevier Ltd. All rights reserved.

  10. Reaction Mechanism of Organocatalytic Michael Addition of Nitromethane to Cinnamaldehyde: A Case Study on Catalyst Regeneration and Solvent Effects.

    Science.gov (United States)

    Świderek, Katarzyna; Nödling, Alexander R; Tsai, Yu-Hsuan; Luk, Louis Y P; Moliner, Vicent

    2018-01-11

    The Michael addition of nitromethane to cinnamaldehyde has been computationally studied in the absence of a catalyst and the presence of a biotinylated secondary amine by a combined computational and experimental approach. The calculations were performed at the density functional theory (DFT) level with the M06-2X hybrid functional, and a polarizable continuum model has been employed to mimic the effect of two different solvents: dichloromethane (DCM) and water. Contrary to common assumption, the product-derived iminium intermediate was absent in both of the solvents tested. Instead, hydrating the C1-C2 double bond in the enamine intermediate directly yields the tetrahedral intermediate, which is key for forming the product and regenerating the catalyst. Enamine hydration is concerted and found to be rate-limiting in DCM but segregated into two non-rate-limiting steps when the solvent is replaced with water. However, further analysis revealed that the use of water as solvent also raises the energy barriers for other chemical steps, particularly the critical step of C-C bond formation between the iminium intermediate and nucleophile; this consequently lowers both the reaction yield and enantioselectivity of this LUMO-lowering reaction, as experimentally detected. These findings provide a logical explanation to why water often enhances organocatalysis when used as an additive but hampers the reaction progress when employed as a solvent.

  11. Determination of organochlorine pesticides in snow water samples by low density solvent based dispersive liquid-liquid microextraction.

    Science.gov (United States)

    Zhao, Wenting; Li, Jindong; Wu, Tong; Wang, Peng; Zhou, Zhiqiang

    2014-09-01

    A simple, rapid, efficient, and environmentally friendly pretreatment based on a low-density solvent based dispersive liquid-liquid microextraction was developed for determining trace levels of 17 organochlorine pesticides in snow. The parameters affecting the extraction efficiency, such as the type and volume of the extraction and dispersive solvents, extraction time, and salt content, were optimized. The optimized conditions yielded a good performance, with enrichment factors ranging from 271 to 474 and recoveries ranging from 71.4 to 114.5% and relative standard deviations between 1.6 and 14.8%. The detection limits, calculated as three times the signal-to-noise ratio, ranged from 0.02 to 0.11 μg/L. The validated method was used to successfully analyze 17 analytes in snow water samples, overcoming the drawbacks of some existing low-density solvent liquid microextraction methods, which require special devices, large volumes of organic solvents, or complicated operation procedures. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Impact of injection solvent composition on protein identification in column-switching chip-liquid chromatography/mass spectrometry.

    Science.gov (United States)

    Houbart, V; Cobraiville, G; Nys, G; Merville, M-P; Fillet, M

    2016-05-06

    In shotgun proteomics, the gold standard technique is reversed-phase liquid chromatography coupled to mass spectrometry. Many researches have been carried out to study the effects on identification performances of chromatographic parameters such as the stationary phase and column dimensions, mobile phase composition and flow rate, as well as the gradient slope and length. However, little attention is usually paid to the injection solvent composition. In this study, we investigated the effect of the injection solvent on protein identification parameters (number of distinct peptides, amino acid coverage and MS/MS search score) as well as sensitivity. Tryptic peptides from six different proteins, covering a wide range of physicochemical properties, were employed as training set. Design of experiments was employed as a tool to highlight the factors related to the composition of the injection solvent that significantly influenced the obtained results. Optimal results for the training set were applied to analysis of more complex samples. The experiments pointed out optimising the composition of the injection solvent had a strong beneficial effect on all the considered responses. On the basis of these results, an approach to determine optimal conditions was proposed to maximise the protein identification performances and detection sensitivity. Copyright © 2016 Elsevier B.V. All rights reserved.

  13. Solvent and Thermally Resistant Polymeric Membranes for Different Applications

    KAUST Repository

    Taghreeed, Jalal

    2016-11-01

    In this work polymeric materials were developed to be used as a solvent and heat resistance membrane for different applications. In ultrafiltration, poly (ether imide sulfone) membranes were manufactured by combining phase inversion and functionalization reaction between epoxy groups and amine modified polyether oligomers (Jeffamine®). Polysilsesquioxanes or oligo silsesquioxanes containing epoxy functionalities were in-situ grown in the casting solution and made available for further reaction with amines in the coagulation/annealing baths. Water permeances up to 1500 l m-2 h-1 bar-1 were obtained with sharp pore size distribution and a pore diameter peak at 66 nm, confirmed by porosimetry, allowing 99.2 % rejection of γ-globulin. The membranes were stable in 50:50 dimethylformamide/water, 50:50 N-methyl pyrrolidone/water and 100 % tetrahydrofuran. In pervaporation, Novel hydrophobic Hyflon®/Extem® and Hyflon®/PVDF were developed and investigated for ethylene glycol dehydration and n-butanol dehydration respectively. For ethylene glycol different Extem® concentrations were evaluated with regard to both flux and amount of water in the permeate side. Eighteen (18) wt% gave more than 90 wt% water in the permeate. Increasing feed temperature from 25 to 85°C increased the water flux from 31 to 91 g m-2 h-1 when using 5 wt% water in ethylene glycol as feed. The water flux of 40 wt% water:ethylene glycol at 45°C was found to be 350 g m-2 h-1. And for n-butanol dehydration the coating protocols for thin defect-free Hyflon® selective layer on the PVDF support was optimized. Water and n-butanol transport was measured, analyzing the effect of operating conditions. The water flux through the newly developed membranes was higher than 150 g m-2 h-1 with selectivity for water higher than 99 wt%. The membrane application can be extended to other solvents, supporting an effective and simple method for dehydration with hydrophobic membranes. In membrane distillation, PVDF

  14. Estimation of Solvent Effects for the Complexing Reaction of Propylene and Nickel Dithiolene

    Directory of Open Access Journals (Sweden)

    Qing-Zhen Han

    2007-12-01

    Full Text Available The formation of olefin complexes is of potential importance in the separation of olefins. The solvents affect the activation energies, and hence the rates and equilibrium constants of the complexing reactions, which performance should be well estimated for the purpose of industrial practice. The solvent effects on the complexing reaction of propylene and nickel dithiolene Ni(S2C2H22 + C2H4=CH2 -> Ni(S2C2H22.C2H4=CH2 are studied in this work, using density functional theory with B3LYP and an Onsager model. Complete optimizations of all the stagnation points are performed in benzene, toluene, tetrahydrofuran, dichloromethane, 1,2-dichloroethane, acetone, ethanol, methanol, 1,2,3-propanetriol, dimethylsulfoxide and water, respectively. The reaction of complexing nickel dithiolene with propylene is a two-step process: the first step coordinates the propylene to S atoms in dithiolene, forming a trans-structural intermediate. The second step then yields the cis-structural product. The activation energy of the first step is higher than that of the second, indicating that the first step is the rate-determining step. The solvents make slight changes in the geometries of the reactants, transition states, intermediates and products. However, the corresponding molecular dipole moment becomes large with increase of the solvent polarity, which is beneficial to accelerate the reaction. Furthermore, the activation energies of the first (or second step will exponentially decrease from 125.0 to 113.0 kJ mol-1 (or from 101.8 to 83.43 kJ mol-1 when the dielectric constants of solvents increase from 1.00 to 78.39, while the reaction rates of the first (or second step exponentially increase from 0.7673x10-9 to 96.20x10-9 s-1 (or from 0.5503 to 1.038 s-1, and the equilibrium constants rapidly increase from 0.5066 to 343.4 lmol-1. The sharp variations of activation energies, rate constants, and equilibrium constants appear when the value of the dielectric

  15. GPU/CPU Algorithm for Generalized Born/Solvent-Accessible Surface Area Implicit Solvent Calculations.

    Science.gov (United States)

    Tanner, David E; Phillips, James C; Schulten, Klaus

    2012-07-10

    Molecular dynamics methodologies comprise a vital research tool for structural biology. Molecular dynamics has benefited from technological advances in computing, such as multi-core CPUs and graphics processing units (GPUs), but harnessing the full power of hybrid GPU/CPU computers remains difficult. The generalized Born/solvent-accessible surface area implicit solvent model (GB/SA) stands to benefit from hybrid GPU/CPU computers, employing the GPU for the GB calculation and the CPU for the SA calculation. Here, we explore the computational challenges facing GB/SA calculations on hybrid GPU/CPU computers and demonstrate how NAMD, a parallel molecular dynamics program, is able to efficiently utilize GPUs and CPUs simultaneously for fast GB/SA simulations. The hybrid computation principles demonstrated here are generally applicable to parallel applications employing hybrid GPU/CPU calculations.

  16. Optimality Conditions in Vector Optimization

    CERN Document Server

    Jiménez, Manuel Arana; Lizana, Antonio Rufián

    2011-01-01

    Vector optimization is continuously needed in several science fields, particularly in economy, business, engineering, physics and mathematics. The evolution of these fields depends, in part, on the improvements in vector optimization in mathematical programming. The aim of this Ebook is to present the latest developments in vector optimization. The contributions have been written by some of the most eminent researchers in this field of mathematical programming. The Ebook is considered essential for researchers and students in this field.

  17. Structural optimization

    CERN Document Server

    MacBain, Keith M

    2009-01-01

    Intends to supplement the engineer's box of analysis and design tools making optimization as commonplace as the finite element method in the engineering workplace. This title introduces structural optimization and the methods of nonlinear programming such as Lagrange multipliers, Kuhn-Tucker conditions, and calculus of variations.

  18. Optimal Flow.

    Science.gov (United States)

    Norman, Donald A.

    1996-01-01

    Discusses the educational applications of experimental psychologist Mihaly Csikszentmihalyi's theory of peak experience, or optimal flow. Optimal flow refers to the receptive state people achieve when they are engaged in interesting and challenging activity. Includes an insightful critique of multimedia instruction from this perspective. (MJP)

  19. High Energy Density in Azobenzene-based Materials for Photo-Thermal Batteries via Controlled Polymer Architecture and Polymer-Solvent Interactions.

    Science.gov (United States)

    Jeong, Seung Pyo; Renna, Lawrence A; Boyle, Connor J; Kwak, Hyunwook S; Harder, Edward; Damm, Wolfgang; Venkataraman, Dhandapani

    2017-12-19

    Energy densities of ~510 J/g (max: 698 J/g) have been achieved in azobenzene-based syndiotactic-rich poly(methacrylate) polymers. The processing solvent and polymer-solvent interactions are important to achieve morphologically optimal structures for high-energy density materials. This work shows that morphological changes of solid-state syndiotactic polymers, driven by different solvent processings play an important role in controlling the activation energy of Z-E isomerization as well as the shape of the DSC exotherm. Thus, this study shows the crucial role of processing solvents and thin film structure in achieving higher energy densities.

  20. Relevance of Frank's solvent classification as typically aqueous and typically non-aqueous to activities of firefly luciferase, alcohol dehydrogenase, and alpha-chymotrypsin in aqueous binaries.

    Science.gov (United States)

    Fadnavis, Nitin Wasantrao; Seshadri, Ramanujam; Sheelu, Gurrala; Madhuri, Kallakunta Vasantha

    2005-01-15

    Effects of cosolvent concentration on activity of fire fly luciferase, alpha-chymotrypsin, and alcohol dehydrogenase from baker's yeast (Saccharomyces cerevisiae) have been studied for several solvents with varying hydrophobicities (logP from +1.0 to -1.65) and polarities (dielectric constant from 7.4 to 109). The inhibitory effect of the cosolvent is examined in light of Frank's classification of solvents into 'typically aqueous (TA)' and 'typically non-aqueous (TNA).' The solvent concentration at which the enzyme activity decreases to half, the C(50) values, for TA solvents such as 1-cyclohexyl-2-pyrrolidinone, 2-butoxyethanol, 1-methyl-2-pyrrolidinone, tetrahydrofuran, t-butanol, and ethanol correlate quite well with their critical hydrophobic interaction concentration, rather than logP, while those for TNA solvents such as acetonitrile, dimethyl formamide, formamide, and dimethyl sulfoxide correlate well with logP. The interactions of TA solvents with proteins appear to be governed mainly by hydrophobic interactions while both hydrophobic and hydrophilic interactions play important role in case of TNA solvents.

  1. PHASE BEHAVIOR OF LIGHT GASES IN HYDROCARBON AND AQUEOUS SOLVENTS

    Energy Technology Data Exchange (ETDEWEB)

    KHALED A.M. GASEM; ROBERT L. ROBINSON, JR.

    1998-08-31

    Under previous support from the Department of Energy, an experimental facility has been established and operated to measure valuable vapor-liquid equilibrium data for systems of interest in the production and processing of coal fluids. To facilitate the development and testing of models for prediction of the phase behavior for such systems, we have acquired substantial amounts of data on the equilibrium phase compositions for binary mixtures of heavy hydrocarbon solvents with a variety of supercritical solutes, including hydrogen, methane, ethane, carbon monoxide, and carbon dioxide. The present project focuses on measuring the phase behavior of light gases and water in Fischer-Tropsch (F-T) type solvents at conditions encountered in indirect liquefaction processes and evaluating and developing theoretically-based correlating frameworks to predict the phase behavior of such systems. Specific goals of the proposed work include (a) developing a state-of-the-art experimental facility to permit highly accurate measurements of equilibrium phase compositions (solubilities) of challenging F-T systems, (b) measuring these properties for systematically-selected binary, ternary and molten F-T wax mixtures to provide critically needed input data for correlation development, (c) developing and testing models suitable for describing the phase behavior of such mixtures, and (d) presenting the modeling results in generalized, practical formats suitable for use in process engineering calculations. During the present period, the Park-Gasem-Robinson (PGR) equation of state (EOS) has been modified to improve its volumetric and equilibrium predictions. Specifically, the attractive term of the PGR equation was modified to enhance the flexibility of the model, and a new expression was developed for the temperature dependence of the attractive term in this segment-segment interaction model. The predictive capability of the modified PGR EOS for vapor pressure, and saturated liquid and

  2. Internet's critical path horizon

    Science.gov (United States)

    Valverde, S.; Solé, R. V.

    2004-03-01

    Internet is known to display a highly heterogeneous structure and complex fluctuations in its traffic dynamics. Congestion seems to be an inevitable result of user's behavior coupled to the network dynamics and it effects should be minimized by choosing appropriate routing strategies. But what are the requirements of routing depth in order to optimize the traffic flow? In this paper we analyse the behavior of Internet traffic with a topologically realistic spatial structure as described in a previous study [S.-H. Yook et al., Proc. Natl Acad. Sci. USA 99, 13382 (2002)]. The model involves self-regulation of packet generation and different levels of routing depth. It is shown that it reproduces the relevant key, statistical features of Internet's traffic. Moreover, we also report the existence of a critical path horizon defining a transition from low-efficient traffic to highly efficient flow. This transition is actually a direct consequence of the web's small world architecture exploited by the routing algorithm. Once routing tables reach the network diameter, the traffic experiences a sudden transition from a low-efficient to a highly-efficient behavior. It is conjectured that routing policies might have spontaneously reached such a compromise in a distributed manner. Internet would thus be operating close to such critical path horizon.

  3. The challenges of controlling organic solvents in a paint factory due to solvent impurity.

    Science.gov (United States)

    Jafari, Mohammad Javad; Karimi, Ali; Rezazadeh Azari, Mansor

    2009-07-01

    In this study, several exhaust ventilation systems were designed and implemented in a paint manufacturing factory, using ACGIH recommendations. The personal exposure of workers to solvents used in the factory was evaluated to examine the role of implemented standard ventilation system. For this purpose, Toluene and Xylene concentration were monitored before and after the application of ventilation systems. Personal samples and subsequent analysis were conducted according to OSHA's method No: 12. Samples were analyzed, using Gas Chromatography. The results showed that the ventilation standards recommended by ACGIH were able to control Toluene and Xylene vapors successfully below the recommended TLVs (e.g. 44.49 ppm and 97.73 ppm respectively). It was also discovered that although Benzene was not reported as a component of the paint, its concentration in breathing zone of workers were much higher than the respective TLV (e.g. 4.5 ppm). This could be from the impurity of solvents used in paint factories which raises new questions. According to IRIS epidemiologic information, it was found that implementation of industrial ventilation systems decrease the relative risk (RR) of leukemia due to exposure to benzene, from 66.4 to 3.2 cases per work life, in this factory. Finally it was deduced that solvents impurities such as Benzene should be seriously considered as a major problem that may not be controlled using ventilation standards recommended by ACGIH for paint mixing and storing process.

  4. Shared Services Management: Critical Factors

    OpenAIRE

    Shouhong Wang; Hai Wang

    2015-01-01

    The cloud computing technology has accelerated shared services in the government and private sectors. This paper proposes a research framework of critical success factors of shared services in the aspects of strategy identification, collaborative partnership networking, optimal shared services process re-designing, and new policies and regulations. A survey has been employed to test the hypotheses. The test results indicate that clear vision of strategies of shared services, long term busines...

  5. Green ultrasound-assisted extraction of carotenoids based on the bio-refinery concept using sunflower oil as an alternative solvent.

    Science.gov (United States)

    Li, Ying; Fabiano-Tixier, Anne Sylvie; Tomao, Valérie; Cravotto, Giancarlo; Chemat, Farid

    2013-01-01

    A green, inexpensive and easy-to-use method for carotenoids extraction from fresh carrots assisted by ultrasound was designed in this work. Sunflower oil was applied as a substitute to organic solvents in this green ultrasound-assisted extraction (UAE): a process which is in line with green extraction and bio-refinery concepts. The processing procedure of this original UAE was first compared with conventional solvent extraction (CSE) using hexane as solvent. Moreover, the UAE optimal conditions for the subsequent comparison were optimized using response surface methodology (RSM) and ultra performance liquid chromatography--diode array detector--mass spectroscopy (UPLC-DAD-MS). The results showed that the UAE using sunflower as solvent has obtained its highest β-carotene yield (334.75 mg/l) in 20 min only, while CSE using hexane as solvent obtained a similar yield (321.35 mg/l) in 60 min. The green UAE performed under optimal extraction conditions (carrot to oil ratio of 2:10, ultrasonic intensity of 22.5 W cm(-2), temperature of 40 °C and sonication time of 20 min) gave the best yield of β-carotene. Copyright © 2012 Elsevier B.V. All rights reserved.

  6. Temporal epileptic seizures and occupational exposure to solvents

    DEFF Research Database (Denmark)

    Jacobsen, M; Bælum, Jesper; Bonde, J P

    1994-01-01

    exposure to a mixture of organic solvents (mainly cyclohexanone, white spirit, and isopropanol). Epileptic seizures of temporal type were occurring in relation to solvent exposure. The seizures disappeared shortly after stopping exposure but returned just after a short term re-exposure to cyclohexanone...

  7. Solvent effects and driving forces in pillararene inclusion complexes.

    Science.gov (United States)

    Schönbeck, Christian; Li, Hui; Han, Bao-Hang; Laursen, Bo W

    2015-06-04

    Pillararenes, a recently discovered class of aromatic macrocycles, form inclusion complexes with a large number of guest molecules, but not much is known about the driving forces of complexation, including the role of the solvent. We have measured the binding thermodynamics for a small number of model complexes in several solvents and used computational chemistry to rationalize the obtained results and identify the driving forces of complexation. Favorable electrostatic interactions between the host and guest are obtained when the charge distribution in the guest matches the negative electrostatic potential in the cavity of the pillararene. Polar guests, however, also interact strongly with polar solvents, thereby shifting the complexation equilibrium away from the complex. The shape of the solvent molecules is another important factor as some solvents are sterically hindered from entering the pillararene cavity. By changing solvent from acetonitrile to o-xylene the binding constant in one case increased more than 4 orders of magnitude. Even electrostatically similar solvents such as o-xylene and p-xylene have very different impacts on the binding constants due to their different abilities to fit into the cavity. The study illustrates the importance of taking into account the interactions between the solvent and the complexing species in the investigation and design of molecular host:guest systems.

  8. Extraction of atropine by ultrasounds in different solvent systems.

    Science.gov (United States)

    Djilani, A; Legseir, B

    2005-03-01

    The use of ultrasounds for extraction of atropine from Egyptian henbane (Hyoscyamus muticus) has been studied. The kinetic of extraction using various solvent systems was carried out. The results obtained have shown that the most efficient system of solvents was CH3OH/CH3CN (80:20). The amount of atropine was calculated by HPLC.

  9. NMR solvent shifts of acetonitrile from frozen density embedding calculations

    NARCIS (Netherlands)

    Bulo, R.E.; Jacob, C.R.; Visscher, L.

    2008-01-01

    We present a density functional theory (DFT) study of solvent effects on nuclear magnetic shielding parameters. As a test example we have focused on the sensitive nitrogen shift of acetonitrile immersed in a selected set of solvents, namely water, chloroform, and cyclohexane. To include the effect

  10. Dense chlorinated solvents and other DNAPLs in groundwater

    DEFF Research Database (Denmark)

    Broholm, K.

    1996-01-01

    Anmeldelse af Pankow,J.F. & Cherry,J.A.: Dense chlorinated solvents and other DNAPLs in groundwater. Waterloo Press, Portland, Oregon, USA, 1996......Anmeldelse af Pankow,J.F. & Cherry,J.A.: Dense chlorinated solvents and other DNAPLs in groundwater. Waterloo Press, Portland, Oregon, USA, 1996...

  11. Abiotic enantiomerization of permethrin and cypermethrin: effects of organic solvents.

    Science.gov (United States)

    Qin, Sujie; Gan, Jianying

    2007-07-11

    All synthetic pyrethroids are chiral compounds, and isomerization has been frequently observed from exposure to certain solvents. However, so far, pyrethroid isomerization caused by solvents has not been characterized at the enantiomer level. In this study, we evaluated the occurrence of enantiomerization of two commonly used pyrethroids, permethrin and cypermethrin, in various organic solvents and solvent-water systems. The four stereoisomers of permethrin were stable under all test conditions. Rapid enantiomerization of cypermethrin was observed in isopropanol and methanol but not in n-hexane, acetone, or methylene chloride. After 4 days at room temperature, 18-39% conversions occurred for the different cypermethrin stereoisomers in isopropanol and methanol, and the enantiomerization invariably took place at the alpha-carbon position. The extent of enantiomerization was affected by temperature dependence and was also influenced by water as a cosolvent. In solvent-water mixtures, cypermethrin underwent gradual enantiomerization in acetone-water and rapid enantiomerization in isopropanol-water or methanol-water. The extent of enantiomerization varied among the solvents and as a function of the solvent-to-water ratio. Results from this study suggest that exposure to certain solvents and water may cause artifacts in chiral analysis and that for isomer-enriched pyrethroid products, such abiotic enantiomerization may render the products less effective because the conversion leads to the formation of inactive stereoisomers.

  12. Highly Efficient and Reproducible Nonfullerene Solar Cells from Hydrocarbon Solvents

    KAUST Repository

    Wadsworth, Andrew

    2017-06-01

    With chlorinated solvents unlikely to be permitted for use in solution-processed organic solar cells in industry, there must be a focus on developing nonchlorinated solvent systems. Here we report high-efficiency devices utilizing a low-bandgap donor polymer (PffBT4T-2DT) and a nonfullerene acceptor (EH-IDTBR) from hydrocarbon solvents and without using additives. When mesitylene was used as the solvent, rather than chlorobenzene, an improved power conversion efficiency (11.1%) was achieved without the need for pre- or post-treatments. Despite altering the processing conditions to environmentally friendly solvents and room-temperature coating, grazing incident X-ray measurements confirmed that active layers processed from hydrocarbon solvents retained the robust nanomorphology obtained with hot-processed chlorinated solvents. The main advantages of hydrocarbon solvent-processed devices, besides the improved efficiencies, were the reproducibility and storage lifetime of devices. Mesitylene devices showed better reproducibility and shelf life up to 4000 h with PCE dropping by only 8% of its initial value.

  13. Filming the Birth of Molecules and Accompanying Solvent Rearrangement

    DEFF Research Database (Denmark)

    Lee, Jae Hyuk; Wulff, Michael; Bratos, Savo

    2013-01-01

    Molecules are often born with high energy and large-amplitude vibrations. In solution, a newly formed molecule cools down by transferring energy to the surrounding solvent molecules. The progression of the molecular and solute−solvent cage structure during this fundamental process has been elusiv...

  14. Availability assessment of a centrifugal contactor solvent extraction system

    Energy Technology Data Exchange (ETDEWEB)

    Haire, M J; Grady, M S; Jubin, R T

    1985-08-01

    A systematic and detailed reliability, availability, and maintainability assessment was made of the preconceptual design of the Breeder Reprocessing Engineering Test solvent extraction system. Initially, the computed availability for the five cycles of solvent extraction was less than the goal for the facility. Contributions to the downtime were identified. Improvements in specifications, design, and equipment configurations that raise the predicted availability are recommended.

  15. Metal Complexes as Color Indicators for Solvent Parameters.

    Science.gov (United States)

    Soukup, Rudolf W.; Schmid, Roland

    1985-01-01

    Although indicators are omnipresent tools in aqueous chemistry, they have not been used extensively to assign solvent properties in nonaqueous systems. Therefore, recent research into a system of metal complexes that can be used to assign donor and acceptor numbers to nonaqueous solvents is summarized. Pertinent experiments are also described. (JN)

  16. Alternative solvents can make preparative liquid chromatography greener

    NARCIS (Netherlands)

    Shen, Y.; Chen, B.; Beek, van T.A.

    2015-01-01

    To make preparative Reversed-Phase High Performance Liquid Chromatography (RP-pHPLC) greener, alternative solvents were considered among others in terms of toxicity, cost, safety, workability, chromatographic selectivity and elution strength. The less toxic solvents ethanol, acetone and ethyl

  17. SAGE 2.1: SOLVENT ALTERNATIVES GUIDE: USER'S GUIDE

    Science.gov (United States)

    The guide provides instruction for using the SAGE (Solvent Alternatives GuidE) software system, version 2.1. SAGE recommends solvent replacements in cleaning and degreasing operations. It leads the user through a question-and-answer session. The user's responses allow the system ...

  18. SAGE 2.0 SOLVENT ALTERNATIVES GUIDE - USER'S GUIDE

    Science.gov (United States)

    The guide provides instruction for using the SAGE (Solvent Alternatives Guide) software system, version 2.O. It assumes that the user is familiar with the fundamentals of operating a personal computer under the Microsoft disk operating system (MS-DOS). AGE recommends solvent repl...

  19. Molecular transport behaviour of organic solvents through halloysite ...

    Indian Academy of Sciences (India)

    The solvent uptake and sorption coefficient decreases with the increase in halloysite loading while diffusion ... above 7.5 phr filler loading were found to be increased due to poor dispersion of halloysite in EVA copolymer matrix. The transport ..... 6.73. 6.84 in reality, as the solvent molecules enter into the polymer sample.

  20. MOLECULAR THERMODYNAMICS IN THE DESIGN OF SUBSTITUTE SOLVENTS

    Science.gov (United States)

    The use of physical properties and fluid behavior from molecular thermodynamics can lead to better decision making in the design of substitute solvents and can greatly reduce the expense and time required to find substitutes compared to designing solvents by experiment. this pape...

  1. Solvent: A Key in Digestive Ripening for Monodisperse Au Nanoparticles

    Science.gov (United States)

    Wang, Peng; Qi, Xuan; Zhang, Xuemin; Wang, Tieqiang; Li, Yunong; Zhang, Kai; Zhao, Shuang; Zhou, Jun; Fu, Yu

    2017-01-01

    This work has mainly investigated the influence of the solvent on the nanoparticles distribution in digestive ripening. The experiments suggested that the solvents played a key role in digestive ripening of Au nanoparticles (Au NPs). For the benzol solvents, the resulting size distribution of Au NPs was inversely related to the solvent polarity. It may be interpreted by the low Gibbs free energy of nanoparticles in the high polarity medium, which was supposedly in favor of reducing the nanoparticles distribution. Through digestive ripening in the highly polar benzol solvent of p-chlorotoluene, monodisperse Au NPs with relative standard deviation (RSD) of 4.8% were achieved. This indicated that digestive ripening was an effective and practical way to prepare high-quality nanoparticles, which holds great promise for the nanoscience and nanotechnology.

  2. PHEA-PLA biocompatible nanoparticles by technique of solvent evaporation from multiple emulsions.

    Science.gov (United States)

    Cavallaro, Gennara; Craparo, Emanuela Fabiola; Sardo, Carla; Lamberti, Gaetano; Barba, Anna Angela; Dalmoro, Annalisa

    2015-11-30

    Nanocarriers of amphiphilic polymeric materials represent versatile delivery systems for poorly water soluble drugs. In this work the technique of solvent evaporation from multiple emulsions was applied to produce nanovectors based on new amphiphilic copolymer, the α,β-poly(N-2-hydroxyethyl)-DL-aspartamide-polylactic acid (PHEA-PLA), purposely synthesized to be used in the controlled release of active molecules poorly soluble in water. To this aim an amphiphilic derivative of PHEA, a hydrophilic polymer, was synthesized by derivatization of the polymeric backbone with hydrophobic grafts of polylactic acid (PLA). The achieved copolymer was thus used to produce nanoparticles loaded with α tocopherol (vitamin E) adopted as lipophilic model molecule. Applying a protocol based on solvent evaporation from multiple emulsions assisted by ultrasonic energy and optimizing the emulsification process (solvent selection/separation stages), PHEA-PLA nanostructured particles with total α tocopherol entrapment efficiency (100%), were obtained. The drug release is expected to take place in lower times with respect to PLA due to the presence of the hydrophilic PHEA, therefore the produced nanoparticles can be used for semi-long term release drug delivery systems. Copyright © 2015 Elsevier B.V. All rights reserved.

  3. How solvent influences the anomeric effect: roles of hyperconjugative versus steric interactions on the conformational preference.

    Science.gov (United States)

    Wang, Changwei; Ying, Fuming; Wu, Wei; Mo, Yirong

    2014-02-21

    The block-localized wave function (BLW) method, which can derive optimal electron-localized state with intramolecular electron delocalization completely deactivated, has been combined with the polarizable continuum model (PCM) to probe the variation of the anomeric effect in solution. Currently both the hyperconjugation and electrostatic models have been called to interpret the anomeric effect in carbohydrate molecules. Here we employed the BLW-PCM scheme to analyze the energy differences between α and β anomers of substituted tetrahydropyran C5OH9Y (Y = F, Cl, OH, NH2, and CH3) and tetrahydrothiopyran C5SH9Y (Y = F, Cl, OH, and CH3) in solvents including chloroform, acetone, and water. In accord with literature, our computations show that for anomeric systems the conformational preference is reduced in solution and the magnitude of reduction increases as the solvent polarity increases. Significantly, on one hand the solute-solvent interaction diminishes the intramolecular electron delocalization in β anomers more than in α anomers, thus destabilizing β anomers relatively. But on the other hand, it reduces the steric effect in β anomers much more than α anomers and thus stabilizes β anomers relatively more, leading to the overall reduction of the anomeric effect in anomeric systems in solutions.

  4. Determination of terpenoid content in pine by organic solvent extraction and fast-GC analysis

    Directory of Open Access Journals (Sweden)

    Anne Elizabeth Harman-Ware

    2016-01-01

    Full Text Available Terpenoids, naturally occurring compounds derived from isoprene units present in pine oleoresin, are a valuable source of chemicals used in solvents, fragrances, flavors and have shown potential use as a biofuel. This paper describes a method to extract and analyze the terpenoids present in loblolly pine saplings and pine lighter wood. Various extraction solvents were tested over different times and temperatures. Samples were analyzed by pyrolysis-molecular beam mass spectrometry before and after extractions to monitor the extraction efficiency. The pyrolysis studies indicated that the optimal extraction method used a 1:1 hexane/acetone solvent system at 22°C for 1 h. Extracts from the hexane/acetone experiments were analyzed using a low thermal mass modular accelerated column heater for fast-GC/FID analysis. The most abundant terpenoids from the pine samples were quantified, using standard curves, and included the monoterpenes, α- and β- pinene, camphene and δ-carene. Sesquiterpenes analyzed included caryophyllene, humulene and α-bisabolene. Diterpenoid resin acids were quantified in derivatized extractions, including pimaric, isopimaric, levopimaric, palustric, dehydroabietic, abietic and neoabietic acids.

  5. Wet flue gas desulphurisation procedures and relevant solvents thermophysical properties determination

    Directory of Open Access Journals (Sweden)

    Živković Nikola V.

    2014-01-01

    Full Text Available In order to mitigate climate change, the priority task is to reduce emissions of greenhouse gases, including sulfur oxides, from stationary power plants. The legal framework of the European Union has limited the allowable emissions of gases with harmful effects and fulfillment of this obligation is also ahead of the Republic of Serbia in the following years. In this paper categorization of wet procedures for sulfur oxides removal is given. Wet procedure with the most widespread industrial application, lime/limestone process, has been described in detail. In addition, the procedures with chemical and physical absorption and solvent thermal regeneration, which recently gained more importance, have been presented. Experimentally determined thermophysical and transport properties of commercially used and alternative solvents, necessary for the equipment design and process optimization, are also given in the paper. The obtained values of densities and viscosities of pure chemicals - solvents, polyethylene glycol 200 (PEG 200, polyethylene glycol 400 (PEG 400, tetraethylene glycol dimethyl ether (TEGDMA, N-methyl-2-pyrolidon (NMP and dimethylaniline (DMA, measured at the atmospheric pressure, are presented as a function of temperature. [Projekat Ministarstva nauke Republike Srbije, br. 172063

  6. Rapid Prototyping of Poly(methyl methacrylate) Microfluidic Systems Using Solvent Imprinting and Bonding

    Science.gov (United States)

    Sun, Xiuhua; Peeni, Bridget A.; Yang, Weichun; Becerril, Hector A.

    2011-01-01

    We have developed a method for rapid prototyping of hard polymer microfluidic systems using solvent imprinting and bonding. We investigated the applicability of patterned SU-8 photoresist on glass as an easily fabricated template for solvent imprinting. Poly(methyl methacrylate) (PMMA) exposed to acetonitrile for 2 min then had an SU-8 template pressed into the surface for 10 min, which provided appropriately imprinted channels and a suitable surface for bonding. After a PMMA cover plate had also been exposed to acetonitrile for 2 min, the imprinted and top PMMA pieces could be bonded together at room temperature with appropriate pressure. The total fabrication time was less than 15 min. Under the optimized fabrication conditions, nearly 30 PMMA chips could be replicated using a single patterned SU-8 master with high chip-to-chip reproducibility. Relative standard deviations were 2.3% and 5.4% for the widths and depths of the replicated channels, respectively. Fluorescently labeled amino acid and peptide mixtures were baseline separated using these PMMA microchips in <15 s. Theoretical plate numbers in excess of 5000 were obtained for a ~3 cm separation distance, and the migration time relative standard deviation for an amino acid peak was 1.5% for intra-day and 2.2% for inter-day analysis. This new solvent imprinting and bonding approach significantly simplifies the process for fabricating microfluidic structures in hard polymers such as PMMA. PMID:17466320

  7. Size effect of water cluster on the excited-state proton transfer in aqueous solvent

    Science.gov (United States)

    Liu, Yu-Hui; Chu, Tian-Shu

    2011-03-01

    Time-dependent density functional theory (TDDFT) was used to investigate the excited-state proton transfer (ESPT) dynamics of 6-hydroxyquinolinium (6HQc) in aqueous solvent, resulting in the excited zwitterionic form (6HQz). The optimized excited-state energy profiles of 6HQc:(H 2O) n complexes have been calculated along the phenolic O sbnd H bond to simulate the minimum energy pathway (MEP) in the excited state. The results suggested that the threshold of the size of the water cluster is 3 for the excited-state proton transfer of 6HQc in aqueous solvent, since the conformation of the stable hydrated proton requires proton transferring to the second or deeper shell of water solvent. Moreover, the stability of the hydrated proton can be improved significantly by adding one more H 2O molecule to form an Eigen cation in the excited-state 6HQz:H 9O 4+. The effect of the size of water cluster on the proton transfer is investigated theoretically in the excited state for the first time.

  8. SCENARIOS EVALUATION TOOL FOR CHLORINATED SOLVENT MNA

    Energy Technology Data Exchange (ETDEWEB)

    Vangelas, K; Brian02 Looney, B; Michael J. Truex; Charles J. Newell

    2006-08-16

    Over the past three decades, much progress has been made in the remediation of chlorinated solvents from the subsurface. Yet these pervasive contaminants continue to present a significant challenge to the U.S. Department of Energy (DOE), other federal agencies, and other public and private organizations. The physical and chemical properties of chlorinated solvents make it difficult to rapidly reach the low concentrations typically set as regulatory limits. These technical challenges often result in high costs and long remediation time frames. In 2003, the DOE through the Office of Environmental Management funded a science-based technical project that uses the U.S. Environmental Protection Agency's technical protocol (EPA, 1998) and directives (EPA, 1999) on Monitored Natural Attenuation (MNA) as the foundation on which to introduce supporting concepts and new scientific developments that will support remediation of chlorinated solvents based on natural attenuation processes. This project supports the direction in which many site owners want to move to complete the remediation of their site(s), that being to complete the active treatment portion of the remedial effort and transition into MNA. The overarching objective of the effort was to examine environmental remedies that are based on natural processes--remedies such as Monitored Natural Attenuation (MNA) or Enhanced Attenuation (EA). The research program did identify several specific opportunities for advances based on: (1) mass balance as the central framework for attenuation based remedies, (2) scientific advancements and achievements during the past ten years, (3) regulatory and policy development and real-world experience using MNA, and (4) exploration of various ideas for integrating attenuation remedies into a systematic set of ''combined remedies'' for contaminated sites. These opportunities are summarized herein and are addressed in more detail in referenced project documents and

  9. Waste and Solvent Composition Limits for Modular Caustic-Side Solvent Extraction Unit (MCU)

    Energy Technology Data Exchange (ETDEWEB)

    Adu-Wusu, Kofi; Waler, Douglas D.; Edwards, Thomas B

    2005-05-26

    This study examined waste feed and solvent limits for the Modular Caustic-Side Solvent Extraction Unit (MCU) currently being designed and built at the Savannah River Site (SRS) to remove cesium from highly alkaline radioactive waste. The study involved proposing ranges for 12 waste feed components (i.e., Na{sup +}, K{sup +}, Cs{sup +}, OH{sup -}, NO{sub 3}{sup -}, NO{sub 2}{sup -}, Cl{sup -}, F{sup -}, SO{sub 4}{sup 2-}, PO{sub 4}{sup 3-}, and CO{sub 3}{sup 2-}, and AlO{sub 2}{sup -}) through a compilation of SRS waste data. Statistical design methods were used to generate numerous wastes with varying compositions from the proposed ranges. An Oak Ridge National Laboratory (ORNL) model called SXFIT was used to predict the cesium extraction distribution coefficients (D-values) between the organic (solvent) phase and the aqueous waste phase using the waste component concentrations as inputs. The D-values from the SXFIT model were used as input along with MCU base case process parameters to a SASSE (Spreadsheet Algorithm for Stagewise Solvent Extraction) model to calculate final cesium concentrations for the MCU. The SASSE model was developed at Argonne National Laboratory (ANL). The SXFIT D-value and the waste component concentration data were used to develop a handier alternative model (neural network model) to the SXFIT model that predicts D-values within 15% of the SXFIT D-values. Both the SXFIT and the neural network model revealed the following. The solvent extractant concentration ratios are approximately equal to the corresponding D-value ratios; a useful feature that could be used to predict extraction D-values when the extractant concentration in the solvent changes in the MCU operation. Also, potassium is the only waste component out of the 12 that shows a distinct relationship with the cesium extraction D-values; an indication of potassium's competition with cesium in the Caustic-Side Solvent Extraction (CSSX) process. A waste feed acceptance model

  10. Solvent effect on the spectral properties of Neutral Red

    Directory of Open Access Journals (Sweden)

    Soliman Ahmed A

    2008-09-01

    Full Text Available Abstract Background The study was aimed at investigating the effect of various solvents on the absorption spectra of Neutral Red, a dye belonging to the quinone-imine class of dyes. The solvents chosen for the study were water, ethanol, acetonitrile, acetone, propan-1-ol, chloroform, nitrobenzene, ethyleneglycol, acetic acid, DMSO and DMF. Results The results have shown that the absorption maxima of dyes are dependent on solvent polarity. In non-hydrogen-bond donating solvents, solvation of dye molecules probably occurs via dipole-dipole interactions, whereas in hydrogen-bond donating solvents the phenomenon is more hydrogen bonding in nature. To estimate the contribution of the different variables on the wave number of the Neutral Red dye, regression analyses using the ECW model were compared with the π* scale model. This showed that the unified scale for estimating the solvent effect on the absorption of the Neutral Red dye is more adopted and more applicable than the π* scale model. Conclusion Absorption maxima of dyes are dependent on solvent polarity. Solvation of dye molecules probably occurs via dipole-dipole interactions in non-hydrogen-bond donating solvents, whereas in hydrogen-bond donating solvents the phenomenon is more hydrogen bonding in nature. The unified scale for estimating the solvent effect on the absorption of Neutral Red dye is more adopted and more applicable than the π* scale model. This may be due to complications from both π-π* charge transfer interactions and incomplete complexation of the solute; these effects are averaged out in the derived β and π parameters and thus limit their applicability.

  11. Solvent Polarity Effect on Nonradiative Decay Rate of Thioflavin T.

    Science.gov (United States)

    Stsiapura, Vitali I; Kurhuzenkau, Siarhei A; Kuzmitsky, Valery A; Bouganov, Oleg V; Tikhomirov, Sergey A

    2016-07-21

    It has been established earlier that fluorescence quantum yield of thioflavin T (ThT)-a probe widely used for amyloid fibrils detection-is viscosity-dependent, and photophysical properties of ThT can be well-described by the fluorescent molecular rotor model, which associates twisted internal charge transfer (TICT) reaction with the main nonradiative decay process in the excited state of the dye. Solutions of ThT in a range of polar solvents were studied using steady-state fluorescence and sub-picosecond transient absorption spectroscopy methods, and we showed that solvent effect on nonradiative transition rate knr cannot be reduced to the dependence on viscosity only and that ∼3 times change of knr can be observed for ThT in aprotic solvents and water, which correlates with solvent polarity. Different behavior was observed in alcohol solutions, particularly in longer n-alcohols, where TICT rate was mainly determined by rotational diffusion of ThT fragments. Quantum-chemical calculations of S0 → S1 transition energy were performed to get insight of polar solvent contribution to the excited-state energy stabilization. Effect of polar solvent on electronic energy levels of ThT was simulated by applying homogeneous electric field according to the Onsager cavity model. Static solvent effect on the excited-state potential energy surface, where charge transfer reaction takes place, was not essential to account for experimentally observed TICT rate differences in water and aprotic solvents. From the other side, nonradiative decay rate of ThT in water, ethylene glycol, and aprotic solvents was found to follow dynamics of polar solvation knr ∼ τS(-1), which can explain dependence of the TICT rate on both polarity and viscosity of the solvents.

  12. Solvent involved self-crystallization of C70 molecules into high definition cube microstructure

    Science.gov (United States)

    Park, Chibeom; Choi, Hee Cheul

    2011-03-01

    C70 molecules dissolved in mesitylene (good solvent) are self-crystallized into cube shape microstructure by the addition of isopropyl alcohol (poor solvent). Through control experiments attempted with different types of alcohols as well as in the replacement of mesitylene with other similar solvents, such as toluene, m-xylene, and m-dichlorobenzene, it is confirmed that mesitylene plays a critical role to guide C70 molecules to form cube microcrystal with high definition edges and surfaces. Thermal gravimetric and crystallographic analyses show that the crystal structure is simple cubic whose unit cell is composed of one C70 and two mesitylene molecules. The photoluminescence intensity from C70 cube crystals are enormously increased compared to C70 powder. Such abnormal photoluminescence increase is mainly attributed to the high crystallinity of C70 cubes as confirmed by time-resolved photoluminescence lifetime measurements. C. Park, E. Yoon, M. Kawano, T. Joo, and H. C. Choi, Angew. Chem. Int. Ed. (to be published).

  13. Spectroscopic and DFT study of solvent effects on the electronic absorption spectra of sulfamethoxazole in neat and binary solvent mixtures.

    Science.gov (United States)

    Almandoz, M C; Sancho, M I; Blanco, S E

    2014-01-24

    The solvatochromic behavior of sulfamethoxazole (SMX) was investigated using UV-vis spectroscopy and DFT methods in neat and binary solvent mixtures. The spectral shifts of this solute were correlated with the Kamlet and Taft parameters (α, β and π(*)). Multiple lineal regression analysis indicates that both specific hydrogen-bond interaction and non specific dipolar interaction play an important role in the position of the absorption maxima in neat solvents. The simulated absorption spectra using TD-DFT methods were in good agreement with the experimental ones. Binary mixtures consist of cyclohexane (Cy)-ethanol (EtOH), acetonitrile (ACN)-dimethylsulfoxide (DMSO), ACN-dimethylformamide (DMF), and aqueous mixtures containing as co-solvents DMSO, ACN, EtOH and MeOH. Index of preferential solvation was calculated as a function of solvent composition and non-ideal characteristics are observed in all binary mixtures. In ACN-DMSO and ACN-DMF mixtures, the results show that the solvents with higher polarity and hydrogen bond donor ability interact preferentially with the solute. In binary mixtures containing water, the SMX molecules are solvated by the organic co-solvent (DMSO or EtOH) over the whole composition range. Synergistic effect is observed in the case of ACN-H2O and MeOH-H2O, indicating that at certain concentrations solvents interact to form association complexes, which should be more polar than the individual solvents of the mixture. Copyright © 2013 Elsevier Ltd. All rights reserved.

  14. Solvent effects on chemical processes. I: Solubility of aromatic and heterocyclic compounds in binary aqueous-organic solvents.

    Science.gov (United States)

    Khossravi, D; Connors, K A

    1992-04-01

    The standard free energy change (delta G0) for equilibrium dissolution in binary solvent mixtures is written as a sum of effects arising from solvent-solvent interactions (the general medium effect), solvent-solute interactions (the solvation effect), and solute-solute interactions (the intersolute effect). The general medium effect is given by gA gamma, where g is a curvature correction factor to the surface tension (gamma) and A is the molecular cavity surface area. A new feature is the definition of gamma to be that value appropriate to the equilibrium mean solvation shell composition. The solvation effect is modeled by stoichiometric stepwise competitive equilibria between the two solvent components for the solute. The intersolute effect includes the crystal energy and solution phase interactions. In this work, water was solvent component 1, and various miscible organic cosolvents served as solvent component 2. Relating all data to the fully aqueous solution gives an explicit expression for delta M delta G0, the solvent effect on the free energy change, as a function of the mole fractions x1 and x2. This function is a binding isotherm. Nonlinear regression leads (for a two-step solvation scheme) to estimates of the solvation exchange constants K1 and K2 and the parameter gA. This relationship was applied to 44 systems comprising combinations of 31 solutes and eight organic cosolvents. Curve fits were good to excellent, and most of the parameter estimates had physically reasonable magnitudes.

  15. Investigating the role of solvent-solute interaction in crystal nucleation of salicylic acid from organic solvents.

    Science.gov (United States)

    Khamar, Dikshitkumar; Zeglinski, Jacek; Mealey, Donal; Rasmuson, Åke C

    2014-08-20

    In previous work, it has been shown that the crystal nucleation of salicylic acid (SA) in different solvents becomes increasingly more difficult in the order: chloroform, ethyl acetate acetonitrile, acetone, methanol, and acetic acid. In the present work, vibration spectroscopy, calorimetric measurements, and density functional theory (DFT) calculations are used to reveal the underlying molecular mechanisms. Raman and infrared spectra suggest that SA exists predominately as dimers in chloroform, but in the other five solvents there is no clear evidence of dimerization. In all solvents, the shift in the SA carbonyl peak reflecting the strength in the solvent-solute interaction is quite well correlated to the nucleation ranking. This shift is corroborated by DFT calculated energies of binding one solvent molecule to the carboxyl group of SA. An even better correlation of the influence of the solvent on the nucleation is provided by DFT calculated energy of binding the complete first solvation shell to the SA molecule. These solvation shell binding energies are corroborated by the enthalpy of solvent-solute interaction as estimated from experimentally determined enthalpy of solution and calculated enthalpy of cavity formation using the scaled particle theory. The different methods reveal a consistent picture and suggest that the stronger the solvent binds to the SA molecule in solution, the slower the nucleation becomes.

  16. Production of electrospun gelatin nanofibers: an optimization study by using Taguchi’s methodology

    Science.gov (United States)

    İnanç Horuz, Tuğba; Bülent Belibağlı, K.

    2017-01-01

    Electrospinning of gelatin from its solution with a non-toxic solvent is not easy. It certainly requires understanding the effects of critical parameters during electrospinning. In this paper, the first aim was to understand how the morphology and diameter of fibers produced from a solution of gelatin in acetic acid (HAc) were affected by solvent concentration and process parameters (flow-rate, applied voltage, distance between the needle-tip and collector) by using Taguchi’s orthogonal design. For this purpose, the optimum levels of factors were determined as follows: voltage 18 kV, flow rate 15 µl min-1, distance 12.5 cm, and HAc concentration 20% in order to obtain the thinnest nanofiber. Secondly, this combination was further validated by conducting a confirmatory experiment using five different gelatin concentrations to observe the effect of concentration. The average diameters of fibers with 24 and 28% gelatin concentrations were found as similar to the optimum conditions estimated, proving the applicability of Taguchi’s method for electrospinning optimization.

  17. Thermal and solvent effects on NMR spectroscopy parameters of a prototypical Chagas disease drug

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2011-07-01

    Full text. Hydrogen bonds in liquids can be of crucial importance for solvent effects in spectroscopy. We have herein computed the nuclear magnetic spin-spin coupling constants (SSCC) involving 15N and 1H nuclei motivated by the relevance of these couplings for the indirect detection of the 15N chemical shifts. Such nJ(N,H) couplings are now also taken as probes for obtaining structural information in proteins. In this work, we focus on the J-couplings; a complete analysis of the NMR spectral data for the compounds studied can be found in previous papers. Thermal and solvent effects on the SSCCs of metronidazole (1) were studied computationally with appropriate quantum-chemical methods. Metronidazole may serve as a model compound to investigate the influence of solvent molecules on the NMR spin-spin coupling constants in heterocyclic rings. We find a hydrogen bond between 1 and a solvent water molecule that is associated with a bond critical point between the imidazole N-3 atom and a water H atom. AIM analysis indicates this hydrogen bond to be mainly electrostatic in nature. Simple static SSCC calculations in vacuo underestimate the nJ(N-3,H) coupling constants because of the neglect of hydrogen bonding. PCM-based treatments perform reasonably well because of the electrostatic character of the hydrogen bond. For more reliable predictions, it is important to take into account the dynamics of the system and to include nearby solvent molecules explicitly. The reduction of the hyperconjugative interactions involving the sigma CH bond or the sigma {sup *}CH antibond (with the coupling nucleus H) that is found in solution appears to be correlated to the reduction of coupling pathways in the imidazole ring. Since nuclear spin orientation information is transferred electronically to the other nuclei in the molecule, experimentally determined J-couplings directly reflect the nature of the chemical bond involved.106,107 Unlike most other NMR properties, which can be

  18. Criticality parameters for tank waste evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Rogers, C.A.; Harris, H.

    1996-08-21

    A summary is provided of basic parameters used to evaluate criticality safety of high-level tank waste at the Hanford Site.Critical sizes and plutonium concentrations are based on a conservative waste model with reduced neutron absorption and optimized water. Figures were provided of sphere and slab minimum critical dimensions and plutonium critical masses.Minimum subcritical limit absorber/plutonium mass ratios are provided for selected waste components. Component contributions to subcriticality can be combined by adding the individual actual-to-minimum subcritical mass fractions. A discussion is provided of the margin of safety inherent in tank waste.

  19. Extraction, scrub, and strip test results for the salt waste processing facility caustic side solvent extraction solvent example

    Energy Technology Data Exchange (ETDEWEB)

    Peters, T. B. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2017-08-01

    An Extraction, Scrub, and Strip (ESS) test was performed on a sample of Salt Waste Processing Facility (SWPF) Caustic-Side Solvent Extraction (CSSX) solvent and salt simulant to determine cesium distribution ratios (D(Cs)), and cesium concentration in the strip effluent (SE) and decontaminated salt solution (DSS) streams; this data will be used by Parsons to help determine if the solvent is qualified for use at the SWPF. The ESS test showed acceptable performance of the solvent for extraction, scrub, and strip operations. The extraction D(Cs) measured 12.9, exceeding the required value of 8. This value is consistent with results from previous ESS tests using similar solvent formulations. Similarly, scrub and strip cesium distribution ratios fell within acceptable ranges.

  20. Extraction, Scrub, and Strip Test Results for the Salt Waste Processing Facility Caustic Side Solvent Extraction Solvent Sample

    Energy Technology Data Exchange (ETDEWEB)

    Peters, T. B. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2017-10-06

    An Extraction, Scrub, and Strip (ESS) test was performed on a sample of Salt Waste Processing Facility (SWPF) Caustic-Side Solvent Extraction (CSSX) solvent and salt simulant to determine cesium distribution ratios (D(Cs)), and cesium concentration in the strip effluent (SE) and decontaminated salt solution (DSS) streams; this data will be used by Parsons to help determine if the solvent is qualified for use at the SWPF. The ESS test showed acceptable performance of the solvent for extraction, scrub, and strip operations. The extraction D(Cs) measured 12.5, exceeding the required value of 8. This value is consistent with results from previous ESS tests using similar solvent formulations. Similarly, scrub and strip cesium distribution ratios fell within acceptable ranges. This revision was created to correct an error. The previous revision used an incorrect set of temperature correction coefficients which resulted in slight deviations from the correct D(Cs) results.