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Sample records for product release kinetics

  1. Aluminum corrosion product release kinetics

    Energy Technology Data Exchange (ETDEWEB)

    Edwards, Matt, E-mail: Matthew.Edwards@cnl.ca; Semmler, Jaleh; Guzonas, Dave; Chen, Hui Qun; Toor, Arshad; Hoendermis, Seanna

    2015-07-15

    Highlights: • Release of Al corrosion product was measured in simulated post-LOCA sump solutions. • Increased boron was found to enhance Al release kinetics at similar pH. • Models of Al release as functions of time, temperature, and pH were developed. - Abstract: The kinetics of aluminum corrosion product release was examined in solutions representative of post-LOCA sump water for both pressurized water and pressurized heavy-water reactors. Coupons of AA 6061 T6 were exposed to solutions in the pH 7–11 range at 40, 60, 90 and 130 °C. Solution samples were analyzed by inductively coupled plasma atomic emission spectroscopy, and coupon samples were analyzed by secondary ion mass spectrometry. The results show a distinct “boron effect” on the release kinetics, expected to be caused by an increase in the solubility of the aluminum corrosion products. New models were developed to describe both sets of data as functions of temperature, time, and pH (where applicable)

  2. Kinetics of corrosion products release from nickel-base alloys corroding in primary water conditions. A new modeling of release

    International Nuclear Information System (INIS)

    Carrette, F.; Guinard, L.; Pieraggi, B.

    2002-01-01

    The radioactivity in the primary circuit arises mainly from the activation of corrosion products in the core of pressurised water reactors; corrosion products dissolve from the oxide scales developed on steam generator tubes of alloy 690. The controlling and modelling of this process require a detailed knowledge of the microstructure and chemical composition of oxide scales as well as the kinetics of their corrosion and dissolution. Alloy 690 was studied as tubes and sheets, with three various surface states (as-received, cold-worked, electropolished). Corrosion tests were performed at 325 C and 155 bar in primary water conditions (B/Li - 1000/2 ppm, [H 2 ] 30 cm 3 .kg -1 TPN, [O 2 ] < 5 ppb); test durations ranged between 24 and 2160 hours. Corrosion tests in the TITANE loop provided mainly corrosion and oxidation kinetics, and tests in the BOREAL loop yielded release kinetics. This study revealed asymptotic type kinetics. Characterisation of the oxide scales grown in representative conditions of the primary circuit was performed by several techniques (SEM, TEM, SIMS, XPS, GIXRD). These analyses revealed the essential role of the fine grained cold-worked scale present on as-received and cold-worked materials. This scale controls the corrosion and release phenomena. The kinetic study and the characterisation of the oxide scales contributed to the modelling of the corrosion/release process. A growth/dissolution model was proposed for corrosion product scales grown in non-saturated dynamic fluid. This model provided the temporal evolution of oxide scales and release kinetics for different species (Fe, Ni, Cr). The model was validated for several surface states and several alloys. (authors)

  3. Hydrogen peroxide release kinetics into saliva from different whitening products: a double-blind, randomized clinical trial.

    Science.gov (United States)

    Marques, Duarte Nuno da Silva; da Mata, António Duarte Sola Pereira; Silveira, João Miguel Lourenço; Marques, Joana Rita Oliveira Faria; Amaral, João Pedro de Almeida Rato; Guilherme, Nuno Filipe Rito Parada Marques

    2012-02-01

    The objective of this study is to compare salivary hydrogen peroxide (HP) release kinetics and potential toxicity of systemic exposure of four different whitening products. A double-blind, randomized controlled trial was conducted in a Portuguese dental faculty clinic. Two hundred forty volunteers were randomized to eight intervention groups. Participants were randomly assigned to receive active or placebo applications of one of four different products: Opalescence 10% PF™ (OPL), Vivastyle® 10%™ (VS10%), Vivadent Paint On Plus™ (PO+), and Trés White Supreme™ (TWS). Saliva collection was obtained by established methods at different times. The HP salivary content was determined by a photometric method. Salivary HP variations, total amount of salivary HP, and counts of subjects above the safe daily HP dose were the main outcome measures. All whitening systems significantly released HP to the saliva when compared to placebo, and all showed different release kinetics. The adaptable tray system (TWS) presented a risk increase of 37% [20-54%, 95% confidence interval] when compared to the other systems. The use of an adaptable tray whitening system with higher concentration of HP increases the toxicity potential.

  4. The Kinetics of Fission Products Release from Microfuel Taking into Account the Trapped Fraction and Limited Solubility Effects

    International Nuclear Information System (INIS)

    Ivanov, A.S.; Rusinkevich, A.A.

    2014-01-01

    In this paper the effect of the oxygen getter on fission products release from the coated particle was studied by the “FP Kinetics” code. Trapped fraction and limited solubility effects taken into consideration. It was shown that these effects have a significant impact on the concentration profile and integral release of fission products. (author)

  5. Pre-steady-state kinetic analysis of 1-deoxy-D-xylulose-5-phosphate reductoisomerase from Mycobacterium tuberculosis reveals partially rate-limiting product release by parallel pathways.

    Science.gov (United States)

    Liu, Juan; Murkin, Andrew S

    2012-07-03

    As part of the non-mevalonate pathway for the biosynthesis of the isoprenoid precursor isopentenyl pyrophosphate, 1-deoxy-D-xylulose-5-phosphate (DXP) reductoisomerase (DXR) catalyzes the conversion of DXP into 2-C-methyl-D-erythritol 4-phosphate (MEP) by consecutive isomerization and NADPH-dependent reduction reactions. Because this pathway is essential to many infectious organisms but is absent in humans, DXR is a target for drug discovery. In an attempt to characterize its kinetic mechanism and identify rate-limiting steps, we present the first complete transient kinetic investigation of DXR. Stopped-flow fluorescence measurements with Mycobacterium tuberculosis DXR (MtDXR) revealed that NADPH and MEP bind to the free enzyme and that the two bind together to generate a nonproductive ternary complex. Unlike the Escherichia coli orthologue, MtDXR exhibited a burst in the oxidation of NADPH during pre-steady-state reactions, indicating a partially rate-limiting step follows chemistry. By monitoring NADPH fluorescence during these experiments, the transient generation of MtDXR·NADPH·MEP was observed. Global kinetic analysis supports a model involving random substrate binding and ordered release of NADP(+) followed by MEP. The partially rate-limiting release of MEP occurs via two pathways--directly from the binary complex and indirectly via the MtDXR·NADPH·MEP complex--the partitioning being dependent on NADPH concentration. Previous mechanistic studies, including kinetic isotope effects and product inhibition, are discussed in light of this kinetic mechanism.

  6. Bioaccessibility of polyphenols associated with dietary fiber and in vitro kinetics release of polyphenols in Mexican 'Ataulfo' mango (Mangifera indica L.) by-products.

    Science.gov (United States)

    Blancas-Benitez, Francisco J; Mercado-Mercado, Gilberto; Quirós-Sauceda, Ana E; Montalvo-González, Efigenia; González-Aguilar, Gustavo A; Sáyago-Ayerdi, Sonia G

    2015-03-01

    The biological properties of polyphenol (PP) depend on its bioaccessibility and bioavailability. Therefore, part of PP released from the food matrix in the gastrointestinal tract through enzymatic hydrolysis is at least partially absorbed. The aim of this study is to determine the bioaccessibility of PP associated with dietary fiber (DF) and the kinetics release of PP in mango (Mangifera indica L.) 'Ataulfo' by-products by an in vitro model. Soluble and insoluble DF values were 7.99 and 18.56% in the mango paste and 6.98 and 22.78% in the mango peel, respectively. PP associated with soluble and insoluble DF was 6.0 and 3.73 g GAE per 100 g in the paste and 4.72 and 4.50 g GAE per 100 g in the peel. The bioaccessibility of PP was 38.67% in the pulp paste and 40.53% in the peel. A kinetics study shows a release rate of 2.66 and 3.27 g PP min(-1) in the paste and peel, respectively. The antioxidant capacity of the paste increased as digestion reached a value of 2.87 mmol TE min(-1) at 180 min. The antioxidant capacity of the peel had its maximum (28.94 mmol TE min(-1)) between 90 and 120 min of digestion; it started with a value of 2.58 mmol TE min(-1), and thereafter increased to 4.20 mmol TE min(-1) at 180 min. The major PPs released during the digestion of paste were gallic and hydroxybenzoic acids, while in the peel, they were hydroxycinnamic and vanillic acids. It was concluded that these phenolic compounds are readily available for absorption in the small intestine and exert different potential health benefits.

  7. Fragmentation and mean kinetic energy release of the nitrogen molecule

    International Nuclear Information System (INIS)

    Santos, A.C.F.; Melo, W.S.; Sant'Anna, M.M.; Sigaud, G.M.; Montenegro, E.C.

    2007-01-01

    Ionization and fragmentation of the N 2 molecule in coincidence with the final projectile charge state have been measured for the impact of 0.188-0.875 MeV/amu He + projectiles. The average kinetic energy release (KER) of the target ionic fragments is derived from the peak widths of their time-of-flight distributions. It is shown that the KER's for singly-charged products follow scaling laws irrespectively to the collision channel

  8. Production kinetics of zirconium tetrachloride

    International Nuclear Information System (INIS)

    Sudjoko, D.; Masduki, B.; Sunardjo; Sulistyo, B.

    1996-01-01

    This research was intended to study the kinetics of zirconium tetrachloride production. The process was carried out in semi continuous reactor, equipped with heater, temperature controller, sublimator and scrubber. The variables investigated were time, temperature and the pellet forming pressure. Within the range of variables studied, the expression of the process in the chemical reaction controller region and diffusion controller region were both presented. (author)

  9. Kinetics of silver release from microfuel with taking into account the limited-solubility effect

    Science.gov (United States)

    Ivanov, A. S.; Rusinkevich, A. A.

    2014-12-01

    The effect of a limited solubility of silver in silicon carbide on silver release from a microfuel with a TRISO coating is studied. It is shown that a limited solubility affects substantially both concentration profiles and silver release from a microfuel over a broad range of temperatures. A procedure is developed for obtaining fission-product concentration profiles in a microfuel and graphs representing the flow and integrated release of fission products on the basis of data from neutron-physics calculations and results obtained by calculating thermodynamics with the aid of the Ivtanthermo code and kinetics with the aid of the FP-Kinetics code. This procedure takes into account a limited solubility of fission products in protective coatings of microfuel.

  10. Drug release kinetic analysis and prediction of release data via polymer molecular weight in sustained release diltiazem matrices.

    Science.gov (United States)

    Adibkia, K; Ghanbarzadeh, S; Mohammadi, G; Khiavi, H Z; Sabzevari, A; Barzegar-Jalali, M

    2014-03-01

    This study was conducted to investigate the effects of HPMC (K4M and K100M) as well as tragacanth on the drug release rate of diltiazem (DLTZ) from matrix tablets prepared by direct compression method.Mechanism of drug transport through the matrices was studied by fitting the release data to the 10 kinetic models. 3 model independent parameters; i. e., mean dissolution time (MDT), mean release rate (MRR) and release rate efficacy (RE) as well as 5 time point approaches were established to compare the dissolution profiles. To find correlation between fraction of drug released and polymer's molecular weight, dissolution data were fitted into two proposed equations.All polymers could sustain drug release up to 10 h. The release data were fitted best to Peppas and Higuchi square root kinetic models considering squared correlation coefficient and mean percent error (MPE). RE and MRR were decreased when polymer to drug ratio was increased. Conversely, t60% was increased with raising polymer /drug ratio. The fractions of drug released from the formulations prepared with tragacanth were more than those formulated using the same amount of HPMC K4M and HPMC K100M.Preparation of DLTZ matrices applying HPMCK4M, HPMC K100M and tragacanth could effectively extend the drug release. © Georg Thieme Verlag KG Stuttgart · New York.

  11. Kinetic Modelling of Drug Release from Pentoxifylline Matrix Tablets based on Hydrophilic, Lipophilic and Inert Polymers

    Directory of Open Access Journals (Sweden)

    Mircia Eleonora

    2015-12-01

    Full Text Available Pentoxifylline is a xanthine derivative used in the treatment of peripheral vascular disease, which because of its pharmacokinetic and pharmacologic profile is an ideal candidate for the development of extended release formulations. The aim of this study is to present a kinetic analysis of the pentoxifylline release from different extended release tablets formulations, using mechanistic and empirical kinetic models. A number of 28 formulations were prepared and analysed; the analysed formulations differed in the nature of the matrix forming polymers (hydrophilic, lipophilic, inert and in their concentrations. Measurements were conducted in comparison with the reference product Trental 400 mg (Aventis Pharma. The conditions for the dissolution study were according to official regulations of USP 36: apparatus no. 2, dissolution medium water, volume of dissolution medium is 1,000 mL, rotation speed is 50 rpm, spectrophotometric assay at 274 nm. Six mathematical models, five mechanistic (0 orders, 1st-order release, Higuchi, Hopfenberg, Hixson-Crowell and one empirical (Peppas, were fitted to pentoxifylline dissolution profile from each pharmaceutical formulation. The representative model describing the kinetics of pentoxifylline release was the 1st-order release, and its characteristic parameters were calculated and analysed.

  12. Kinetics of extracellular release of 14C-labelled organic carbon by submerged macrophytes

    International Nuclear Information System (INIS)

    Soendergaard, M.

    1981-01-01

    The release of extracellular organic carbon (EOC) by six submerged freswater macrophytes was measured in time course studies with a 14 C-technique. Incubation in light in an open water-flow system made it possible to assay the time courses of 14 C-fixation and the simultaneous release of labelled EOC. Heterotrophic utilization of the released products by epiphytic communities was measured. Two patterns of release kinetics were found: (1) Constant rates of release occurred during the incubations, (2) The rates still increased after 24 h of incubation. During the first hours of incubation the rates of release increased in all species. Elodea reached constant rates after 2-4 h and Littorella and Ceratophyllum demersum after about 20 h. In the experiments with C. submersum and Nitella the rates of release increased almost linearly during the entire incubation period. The kinetics of release were in agreement with the molecular weight distribution of the dissolved EOC measured with gel chromatography. Low molecular weight products ( 10000 Daltons) dominated the dissolved EOC released by C. submersum and Nitella. A large fraction (18-60%) of the total EOC could be recovered on filters with a pore size of 0.2 μm. This particulate fraction probably represents some abiotic removal. The quantities of relase were low in all species and did not exceed 0.9% of the photosynthetic carbon fixation. Heterotrophic uptake by the epiphytic communities was less than 10% of the EOC released. The results emphasize that the 14 C-labelling of extracellular products is a time dependent process. (author)

  13. Phenobarbital loaded microemulsion: development, kinetic release and quality control

    Directory of Open Access Journals (Sweden)

    Kayo Alves Figueiredo

    Full Text Available ABSTRACT This study aimed to obtain and characterize a microemulsion (ME containing phenobarbital (PB. The PB was incorporated in the proportion of 5% and 10% in a microemulsion system containing Labrasol(r, ethanol, isopropyl myristate and purified water. The physicochemical characterization was performed and the primary stability of the ME was evaluated. An analytical method was developed using spectrophotometry in UV = 242 nm. The kinetics of the in vitro release (Franz model of the ME and the emulsion (EM containing PB was evaluated. The incorporation of PB into ME at concentrations of 5 and 10% did not change pH and resistance to centrifugation. There was an increase in particle size, a decrease of conductivity and a change in the refractive index in relation to placebo ME. The ME remained stable in preliminary stability tests. The analytical method proved to be specific, linear, precise, accurate and robust. Regarding the kinetics of the in vitro release, ME obtained an in vitro release profile greater than the EM containing PB. Thus, the obtained ME has a potential for future transdermal application, being able to compose a drug delivery system for the treatment of epilepsy.

  14. Tunneling and reflection in unimolecular reaction kinetic energy release distributions

    Science.gov (United States)

    Hansen, K.

    2018-02-01

    The kinetic energy release distributions in unimolecular reactions is calculated with detailed balance theory, taking into account the tunneling and the reflection coefficient in three different types of transition states; (i) a saddle point corresponding to a standard RRKM-type theory, (ii) an attachment Langevin cross section, and (iii) an absorbing sphere potential at short range, without long range interactions. Corrections are significant in the one dimensional saddle point states. Very light and lightly bound absorbing systems will show measurable effects in decays from the absorbing sphere, whereas the Langevin cross section is essentially unchanged.

  15. Electrochemically controlled release of anticancer drug methotrexate using nanostructured polypyrrole modified with cetylpyridinium: Release kinetics investigation

    International Nuclear Information System (INIS)

    Alizadeh, Naader; Shamaeli, Ehsan

    2014-01-01

    A new simple strategy for direct electrochemical incorporation of chemotherapeutic methotrexate (MTX) into conductive polypyrrole (PPy) has been suggested for an electrochemically controlled loading and release system. Electropolymerization of MTX doped polypyrrole yielded poor quality with low efficiency of doping, but a well-doped, nanostructure and increased capacity of drug loading (24.5 mg g −1 ) has been obtained in the presence of cetylpyridinium (CP) as a modifier. When CP was preloaded onto PPy, the hydrophobic surface of the PPy serves as a backbone to which the hydrophobic chain of the CP can be attached. Electrostatic interaction between cationic CP with anionic MTX and aromatic interaction between pyridinium head of CP with pyrimidine and pyrazine rings of MTX increases drug doping. Then release kinetics were investigated at various applied potentials and temperatures. Kinetics analysis based on Avrami's equation showed that the drug release was controlled and accelerated by increasing temperature and negative potential and sustained by increasing positive potential. At open circuit condition, the release parameter (n) represented a diffusive mechanism and at applying electrochemical potentials, a first-order mode. Activation energy parameters (E a , ΔG ≠ , ΔH ≠ and ΔS ≠ ) and half-life time (t 1/2 ) of drug release are also analyzed as a function of applied potential. The nanostructured polymer films (PPy/CP/MTX) were characterized by several techniques: scanning electron microscopy, Furrier transforms Infrared, UV-vis spectroscopy. Overall, our results demonstrate that the PPy/CP/MTX films, combined with electrical stimulation, permit a programmable release of MTX by altering the interaction strength between the PPy/CP and MTX

  16. Kinetics of radiocesium released from contaminated soil by fertilizer solutions

    International Nuclear Information System (INIS)

    Chiang, P.N.; Wang, M.K.; Huang, P.M.; Wang, J.J.

    2008-01-01

    137 Cs is one of the major artificial radionuclides found in environments; but the mechanisms behind fertilizer-induced 137 Cs desorption from soil remain unknown. This study aimed to investigate the kinetics and mechanisms underlying the various cations and anions that cause Cs release from soil under acidic conditions. NH 4 H 2 PO 4 (1 M), 0.5 M (NH 4 ) 2 SO 4 , 1 M NH 4 Cl, 1 M KCl or 1 M NaCl solutions were added to 137 Cs-contaminated soil. The power function model well described the short term 137 Cs desorption with the solutions. The rate coefficients for 137 Cs release from soil in NH 4 H 2 PO 4 , (NH 4 ) 2 SO 4 , NH 4 Cl, and KCl solutions were 7.7, 7.3, 6.8, and 6.1 times higher than the rate observed in a NaCl solution, respectively. The NH 4 H 2 PO 4 and (NH 4 ) 2 SO 4 solutions induced significantly greater 137 Cs release from the contaminated soil than the NH 4 Cl, KCl and NaCl solutions. After four times repeated extractions with the fertilizer solutions, the total amount of 137 Cs extracted by (NH 4 ) 2 SO 4 and NH 4 Cl solutions reached equilibrium, while that extracted using an NH 4 H 2 PO 4 solution continued to increase. The combined effect of phosphate and protons was the major mechanism behind 137 Cs release from contaminated soils, when an NH 4 H 2 PO 4 solution was used

  17. Polymeric nanoparticles containing diazepam: preparation, optimization, characterization, in-vitro drug release and release kinetic study

    Science.gov (United States)

    Bohrey, Sarvesh; Chourasiya, Vibha; Pandey, Archna

    2016-03-01

    Nanoparticles formulated from biodegradable polymers like poly(lactic-co-glycolic acid) (PLGA) are being extensively investigated as drug delivery systems due to their two important properties such as biocompatibility and controlled drug release characteristics. The aim of this work to formulated diazepam loaded PLGA nanoparticles by using emulsion solvent evaporation technique. Polyvinyl alcohol (PVA) is used as stabilizing agent. Diazepam is a benzodiazepine derivative drug, and widely used as an anticonvulsant in the treatment of various types of epilepsy, insomnia and anxiety. This work investigates the effects of some preparation variables on the size and shape of nanoparticles prepared by emulsion solvent evaporation method. These nanoparticles were characterized by photon correlation spectroscopy (PCS), transmission electron microscopy (TEM). Zeta potential study was also performed to understand the surface charge of nanoparticles. The drug release from drug loaded nanoparticles was studied by dialysis bag method and the in vitro drug release data was also studied by various kinetic models. The results show that sonication time, polymer content, surfactant concentration, ratio of organic to aqueous phase volume, and the amount of drug have an important effect on the size of nanoparticles. Hopefully we produced spherical shape Diazepam loaded PLGA nanoparticles with a size range under 250 nm with zeta potential -23.3 mV. The in vitro drug release analysis shows sustained release of drug from nanoparticles and follow Korsmeyer-Peppas model.

  18. Fission-product release during accidents

    International Nuclear Information System (INIS)

    Hunt, C.E.L.; Cox, D.S.

    1991-09-01

    One of the aims when managing a reactor accident is to minimize the release of radioactive fission products. Release is dependent not only on the temperature, but also on the partial pressure of oxygen. Strongly oxidizing atmospheres, such as those that occurred during the Chernobyl accident, released semi-volatile elements like ruthenium, which has volatile oxides. At low temperatures, UO 2 oxidization to U 3 O 8 can result in extensive breakup of the fuel, resulting in the release of non-volatile fission products as aerosols. Under less oxidizing conditions, when hydrogen accumulates from the zirconium-water reaction, the resulting low oxygen partial pressure can significantly reduce these reactions. At TMI-2, only the noble gases and volatile fission products were released in significant quantities. A knowledge of the effect of atmosphere as well as temperature on the release of fission products from damaged reactor cores is therefore a useful, if not necessary, component of information required for accident management

  19. Variation of kinetic energy release with temperature and electron energy for unimolecular ionic transitions

    International Nuclear Information System (INIS)

    Rabia, M.A.; Fahmy, M.A.

    1992-01-01

    The kinetic energy released during seven unimolecular ionic transitions, generated from benzyl alcohol and benzyl amine have been studied as a function of ion source temperature and ionizing electron energy. Only, the kinetic energy released during H CN elimination from fragment [C 7 H 8 N]+ ion of benzyl amine displays a temperature dependence. For only two transitions, generated from benzyl alcohol, the kinetic energy released show a significant ionizing electron energy dependence. These results may reveal the role of the internal energy of reacting ions in producing the kinetic energy released some transitions produced from benzyl alcohol

  20. The Kinetics of Ampicillin Release from Hydroxyapatite for Bones Regeneration

    Directory of Open Access Journals (Sweden)

    Giovanilton Ferreira da Silva

    2009-01-01

    Full Text Available Semisynthetic beta-lactam antibiotics are among the most used pharmaceuticals. Their use in veterinary and human medicine is in continuous expansion. There is a growing need for developing bioactive implants. Advantages of implantable drug delivery tools can include high release efficiency, precise dose control, low toxicity, and allow to overcome disadvantages connected with conventional methods. In this respect, hydroxyapatite (HA is an elective material. It enables to produce architectures similar to those of real bones. Here we studied a kinetic model to describe ampicillin release from HA. In the course of adsorption experiment, ampicillin was dissolved, maintained at 30∘C and shaken at 60 strokes/minute. Samples were withdrawn periodically for analysis and then returned to the mixture. Adsorbed amounts were measured by the difference of the concentration of the antibiotics before and after adsorption using UV adsorption at 225 nm. The aim of this work was to evaluate its application as ampicillin delivery carrier.

  1. Fuel morphology effects on fission product release

    International Nuclear Information System (INIS)

    Osetek, D.J.; Hartwell, J.K.; Cronenberg, A.W.

    1986-01-01

    Results are presented of fission product release behavior observed during four severe fuel damage tests on bundles of UO 2 fuel rods. Transient temperatures up to fuel melting were obtained in the tests that included both rapid and slow cooldown, low and high (36 GWd/t) burnup fuel and the addition of Ag-In-Cd control rods. Release fractions of major fission product species and release rates of noble gas species are reported. Significant differences in release behavior are discussed between heatup and cooldown periods, low and high burnup fuel and long- and short-lived fission products. Explanations for the observed differences are offered that relate fuel morphology changes to the releases

  2. Prodigiosin release from an implantable biomedical device: kinetics of localized cancer drug release

    Energy Technology Data Exchange (ETDEWEB)

    Danyuo, Y.; Obayemi, J.D.; Dozie-Nwachukwu, S. [Department of Materials Science and Engineering, African University of Science and Technology (AUST), Abuja, Federal Capital Territory (Nigeria); Ani, C.J. [Department of Theoretical Physics, African University of Science and Technology (AUST), Abuja, Federal Capital Territory (Nigeria); Odusanya, O.S. [Biotechnology and Genetic Engineering Advanced Laboratory, Sheda Science and Technology Complex (SHESTCO), Abuja, Federal Capital Territory (Nigeria); Oni, Y. [Department of Chemistry, Bronx Community College, New York, NY (United States); Anuku, N. [Department of Chemistry, Bronx Community College, New York, NY (United States); Princeton Institute for the Science and Technology of Materials (PRISM), 70 Prospect Street, Princeton, NJ 08544 (United States); Malatesta, K. [Department of Chemistry, Bronx Community College, New York, NY (United States); Soboyejo, W.O., E-mail: soboyejo@princeton.edu [Department of Materials Science and Engineering, African University of Science and Technology (AUST), Abuja, Federal Capital Territory (Nigeria); Princeton Institute for the Science and Technology of Materials (PRISM), 70 Prospect Street, Princeton, NJ 08544 (United States); Department of Mechanical and Aerospace Engineering 1 Olden Street, Princeton, NJ 08544 (United States)

    2014-09-01

    This paper presents an implantable encapsulated structure that can deliver localized heating (hyperthermia) and controlled concentrations of prodigiosin (a cancer drug) synthesized by bacteria (Serratia marcesce (subsp. marcescens)). Prototypical Poly-di-methyl-siloxane (PDMS) packages, containing well-controlled micro-channels and drug storage compartments, were fabricated along with a drug-storing polymer produced by free radical polymerization of Poly(N-isopropylacrylamide)(PNIPA) co-monomers of Acrylamide (AM) and Butyl-methacrylate (BMA). The mechanisms of drug diffusion of PNIPA-base gels were elucidated. Scanning Electron Microscopy (SEM) was also used to study the heterogeneous porous structure of the PNIPA-based gels. The release exponents, n, of the gels were found to between 0.5 and 0.7. This is in the range expected for Fickian (n = 0.5). Deviation from Fickian diffusion was also observed (n > 0.5) diffusion. The gel diffusion coefficients were shown to vary between 2.1 × 10{sup −12} m{sup 2}/s and 4.8 × 10{sup −6} m{sup 2}/s. The implications of the results are then discussed for the localized treatment of cancer via hyperthermia and the controlled delivery of prodigiosin from encapsulated PNIPA-based devices. - Highlights: • Fabricated thermo-sensitive hydrogels for localized drug release from an implantable biomedical device. • Determined the cancer drug diffusion mechanisms of PNIPA-co-AM copolymer hydrogel. • Encapsulated PNIPA-based hydrogels in PDMS capsules for controlled drug delivery. • Established the kinetics of drug release from gels and channels in an implantable biomedical device. • Demonstrated the potential for the controlled release of prodigiosin (PG) as an anticancer drug.

  3. Prodigiosin release from an implantable biomedical device: kinetics of localized cancer drug release

    International Nuclear Information System (INIS)

    Danyuo, Y.; Obayemi, J.D.; Dozie-Nwachukwu, S.; Ani, C.J.; Odusanya, O.S.; Oni, Y.; Anuku, N.; Malatesta, K.; Soboyejo, W.O.

    2014-01-01

    This paper presents an implantable encapsulated structure that can deliver localized heating (hyperthermia) and controlled concentrations of prodigiosin (a cancer drug) synthesized by bacteria (Serratia marcesce (subsp. marcescens)). Prototypical Poly-di-methyl-siloxane (PDMS) packages, containing well-controlled micro-channels and drug storage compartments, were fabricated along with a drug-storing polymer produced by free radical polymerization of Poly(N-isopropylacrylamide)(PNIPA) co-monomers of Acrylamide (AM) and Butyl-methacrylate (BMA). The mechanisms of drug diffusion of PNIPA-base gels were elucidated. Scanning Electron Microscopy (SEM) was also used to study the heterogeneous porous structure of the PNIPA-based gels. The release exponents, n, of the gels were found to between 0.5 and 0.7. This is in the range expected for Fickian (n = 0.5). Deviation from Fickian diffusion was also observed (n > 0.5) diffusion. The gel diffusion coefficients were shown to vary between 2.1 × 10 −12 m 2 /s and 4.8 × 10 −6 m 2 /s. The implications of the results are then discussed for the localized treatment of cancer via hyperthermia and the controlled delivery of prodigiosin from encapsulated PNIPA-based devices. - Highlights: • Fabricated thermo-sensitive hydrogels for localized drug release from an implantable biomedical device. • Determined the cancer drug diffusion mechanisms of PNIPA-co-AM copolymer hydrogel. • Encapsulated PNIPA-based hydrogels in PDMS capsules for controlled drug delivery. • Established the kinetics of drug release from gels and channels in an implantable biomedical device. • Demonstrated the potential for the controlled release of prodigiosin (PG) as an anticancer drug

  4. Fission product release mechanisms and groupings

    International Nuclear Information System (INIS)

    Iglesia, F.C.; Brito, A.C.; Liu, Y.

    1995-01-01

    During CANDU postulated accidents the reactor fuel is estimated to be exposed to a variety of conditions. These conditions are dynamic and, during the course of an accident, the fuel may experience a wide range of temperatures and conditions from highly oxidizing to mildly reducing environments. The exposure of the reactor fuel to these environments and temperatures may affect its stoichiometry and release performance. In this paper a review of the important fission product release mechanisms is presented, the results of three out-of-pile experimental programs are summarized, and fission product release groups, for both oxidizing and reducing conditions are proposed. (author)

  5. Fission product release mechanisms and groupings

    Energy Technology Data Exchange (ETDEWEB)

    Iglesia, F C; Brito, A C; Liu, Y [Ontario Hydro, Toronto, ON (Canada); and others

    1996-12-31

    During CANDU postulated accidents the reactor fuel is estimated to be exposed to a variety of conditions. These conditions are dynamic and, during the course of an accident, the fuel may experience a wide range of temperatures and conditions from highly oxidizing to mildly reducing environments. The exposure of the reactor fuel to these environments and temperatures may affect its stoichiometry and release performance. In this paper a review of the important fission product release mechanisms is presented, the results of three out-of-pile experimental programs are summarized, and fission product release groups, for both oxidizing and reducing conditions are proposed. (author) 92 refs., 6 tabs.

  6. Production of a sterile species: Quantum kinetics

    Science.gov (United States)

    Boyanovsky, D.; Ho, C. M.

    2007-10-01

    Production of a sterile species is studied within an effective model of active-sterile neutrino mixing in a medium in thermal equilibrium. The quantum kinetic equations for the distribution functions and coherences are obtained from two independent methods: the effective action and the quantum master equation. The decoherence time scale for active-sterile oscillations is τdec=2/Γaa, but the evolution of the distribution functions is determined by the two different time scales associated with the damping rates of the quasiparticle modes in the medium: Γ1=Γaacos⁡2θm; Γ2=Γaasin⁡2θm where Γaa is the interaction rate of the active species in the absence of mixing and θm the mixing angle in the medium. These two time scales are widely different away from Mikheyev-Smirnov-Wolfenstein resonances and preclude the kinetic description of active-sterile production in terms of a simple rate equation. We give the complete set of quantum kinetic equations for the active and sterile populations and coherences and discuss in detail the various approximations. A generalization of the active-sterile transition probability in a medium is provided via the quantum master equation. We derive explicitly the usual quantum kinetic equations in terms of the “polarization vector” and show their equivalence to those obtained from the quantum master equation and effective action.

  7. Correlation of recent fission product release data

    International Nuclear Information System (INIS)

    Kress, T.S.; Lorenz, R.A.; Nakamura, T.; Osborne, M.F.

    1989-01-01

    For the calculation of source terms associated with severe accidents, it is necessary to model the release of fission products from fuel as it heats and melts. Perhaps the most definitive model for fission product release is that of the FASTGRASS computer code developed at Argonne National Laboratory. There is persuasive evidence that these processes, as well as additional chemical and gas phase mass transport processes, are important in the release of fission products from fuel. Nevertheless, it has been found convenient to have simplified fission product release correlations that may not be as definitive as models like FASTGRASS but which attempt in some simple way to capture the essence of the mechanisms. One of the most widely used such correlation is called CORSOR-M which is the present fission product/aerosol release model used in the NRC Source Term Code Package. CORSOR has been criticized as having too much uncertainty in the calculated releases and as not accurately reproducing some experimental data. It is currently believed that these discrepancies between CORSOR and the more recent data have resulted because of the better time resolution of the more recent data compared to the data base that went into the CORSOR correlation. This document discusses a simple correlational model for use in connection with NUREG risk uncertainty exercises. 8 refs., 4 figs., 1 tab

  8. Release of fission products in transients

    International Nuclear Information System (INIS)

    Christensen, H.; Lundqwist, R.

    1979-07-01

    A station for automatic sampling of coolant has been put in operation at the Oskarshamn-1 reactor. The release of 131 J and other fission products in spikes in connection with reactor trips and scheduled shutdowns has been measured. A model developed at General Electric has been used to predict the spike release in Oskarshamn-1 and the predicted values have been compared with experimental values. Literature data of iodine spikes in BWR and PWR have been reviewed. (author)

  9. Understanding release kinetics of biopolymer drug delivery microcapsules for biomedical applications

    International Nuclear Information System (INIS)

    Desai, Salil; Perkins, Jessica; Harrison, Benjamin S.; Sankar, Jag

    2010-01-01

    Drug delivery and dosage concentrations are considered as major focal points in conventional as well as battlefield emergency medicine. The concept of localizing drug delivery via microcapsules is an evolving field to confine the adverse side effects of high concentration drug doses. This paper focuses on understanding release kinetics through biopolymer microcapsules for time-dependent drug release. Calcium alginate microcapsules were manufactured using a direct-write inkjet technique. Rhodamine 6G was used as the release agent to observe the release kinetics from calcium alginate beads in distilled water. A design of experiments was constructed to compare the effect of the microcapsule diameter and different concentrations of calcium chloride (M) and sodium alginate (%, w/v) solutions on the release kinetics profiles of the microcapsules. This research gives insight to identify favorable sizes of microcapsules and concentrations of sodium alginate and calcium chloride solutions for controlled release behavior of drug delivery microcapsules.

  10. Investigating the in vitro drug release kinetics from controlled release diclofenac potassium-ethocel matrix tablets and the influence of co-excipients on drug release patterns.

    Science.gov (United States)

    Shah, Shefaat Ullah; Shah, Kifayat Ullah; Rehman, Asimur; Khan, Gul Majid

    2011-04-01

    The objective of the study was to formulate and evaluate controlled release polymeric tablets of Diclofenac Potassium for the release rate, release patterns and the mechanism involved in the release process of the drug. Formulations with different types and grades of Ethyl Cellulose Ether derivatives in several drug-to-polymer ratios (D:P) were compressed into tablets using the direct compression method. In vitro drug release studies were performed in phosphate buffer (pH 7.4) as dissolution medium by using USP Method-1 (Rotating Basket Method). Similarity factor f2 and dissimilarity factor f1 were applied for checking the similarities and dissimilarities of the release profiles of different formulations. For the determination of the release mechanism and drug release kinetics various mathematical/kinetic models were employed. It was found that all of the Ethocel polymers could significantly slow down the drug release rate with Ethocel FP polymers being the most efficient, especially at D:P ratios of 10:03 which lead towards the achievement of zero or near zero order release kinetics.

  11. Tritium breeding and release-rate kinetics from neutron-irradiated lithium oxide

    International Nuclear Information System (INIS)

    Quanci, J.F.

    1989-01-01

    The research encompasses the measurement of the tritium breeding and release-rate kinetics from lithium oxide, a ceramic tritium-breeding material. A thermal extraction apparatus which allows the accurate measurement of the total tritium inventory and release rate from lithium oxide samples under different temperatures, pressures and carrier-gas compositions with an uncertainty not exceeding 3% was developed. The goal of the Lithium Blanket Module program was to determine if advanced computer codes could accurately predict the tritium production in the lithium oxide blanket of a fusion power plant. A fusion blanket module prototype was built and irradiated with a deuterium-tritium fusion-neutron source. The tritium production throughout the module was modeled with the MCNP three dimensional Monte Carlo code and was compared to the assay of the tritium bred in the module. The MCNP code accurately predicted tritium-breeding trends but underestimated the overall tritium breeding by 30%. The release rate of tritium from small grain polycrystalline sintered lithium oxides with a helium carrier gas from 300 to 450 C was found to be controlled by the first order surface desorption of monotritiated water. When small amounts of hydrogen were added to the helium carrier gas, the first order rate constant increased from the isotopic exchange of hydrogen for tritium at the lithium oxide surface occurring in parallel with the first order desorption process. The isotopic-exchange first order rate constant temperature dependence and hydrogen partial pressure dependence were evaluated

  12. Tritium breeding and release-rate kinetics from neutron-irradiated lithium oxide

    International Nuclear Information System (INIS)

    Quanci, J.F.

    1989-01-01

    The research encompasses the measurement of the tritium breeding and release-rate kinetics from lithium oxide, a ceramic tritium-breeding material. A thermal extraction apparatus which allows the accurate measurement of the total tritium inventory and release rate from lithium oxide samples under different temperatures, pressures and carrier-gas compositions with an uncertainty not exceeding 3% was developed. The goal of the Lithium Blanket Module program was to determine if advanced computer codes could accurately predict the tritium production in the lithium oxide blanket of a fusion power plant. A fusion blanket module prototype, was built and irradiated with a deuterium-tritium fusion-neutron source. The tritium production throughout the module was modeled with the MCNP three dimensional Monte Carlo code and was compared to the assay of the tritium bred in the module. The MCNP code accurately predicted tritium-breeding trends but underestimated the overall tritium breeding by 30%. The release rate of tritium from small grain polycrystalline sintered lithium oxide with a helium carrier gas from 300 to 450 C was found to be controlled by the first order surface desorption of mono-tritiated water. When small amounts of hydrogen were added to the helium carrier gas, the first order rate constant increased from the isotopic exchange of hydrogen for tritium at the lithium oxide surface occurring in parallel with the first order desorption process. The isotopic-exchange first order rate constant temperature dependence and hydrogen partial pressure dependence were evaluated. Large single crystals of lithium oxide were fabricated by the vacuum fusion technique. The release rate of tritium from the large single crystals was found to be controlled by diffusion, and the mixed diffusion-desorption controlled release regime

  13. Validation of kinetic modeling of progesterone release from polymeric membranes

    Directory of Open Access Journals (Sweden)

    Analia Irma Romero

    2018-01-01

    Full Text Available Mathematical modeling in drug release systems is fundamental in development and optimization of these systems, since it allows to predict drug release rates and to elucidate the physical transport mechanisms involved. In this paper we validate a novel mathematical model that describes progesterone (Prg controlled release from poly-3-hydroxybutyric acid (PHB membranes. A statistical analysis was conducted to compare the fitting of our model with six different models and the Akaike information criterion (AIC was used to find the equation with best-fit. A simple relation between mass and drug released rate was found, which allows predicting the effect of Prg loads on the release behavior. Our proposed model was the one with minimum AIC value, and therefore it was the one that statistically fitted better the experimental data obtained for all the Prg loads tested. Furthermore, the initial release rate was calculated and therefore, the interface mass transfer coefficient estimated and the equilibrium distribution constant of Prg between the PHB and the release medium was also determined. The results lead us to conclude that our proposed model is the one which best fits the experimental data and can be successfully used to describe Prg drug release in PHB membranes.

  14. GENIE Production Release 2.10.0

    Energy Technology Data Exchange (ETDEWEB)

    Alam, M. [Aligarh Muslim Univ., Aligarh (India). Dept. of Physics; Andreopoulos, C. [Univ. of Liverpool (United Kingdom). Dept. of Physics; Science and Technology Facilities Council (STFC), Oxford (United Kingdom). Rutherford Appleton Lab. (RAL); Athar, M. [Aligarh Muslim Univ., Aligarh (India). Dept. of Physics; Bodek, A. [Univ. of Rochester, NY (United States). Dept. of Physics; Christy, E. [Hampton Univ., Hampton, VA (United States). Dept. of Physics; Coopersmith, B. [Univ. of Rochester, NY (United States). Dept. of Physics; Dennis, S. [Univ. of Warwick, Coventry (United Kingdom). Dept .of Physics; Dytman, S. [Univ. of Pittsburgh, PA (United States). Dept. of Physics and Astronomy; Gallagher, H. [Tufts Univ., Medford, MA (United States). Dept. of Physics and Astronomy; Geary, N. [Univ. of Pittsburgh, PA (United States). Dept. of Physics and Astronomy; Golan, T. [Univ. of Rochester, NY (United States). Dept. of Physics; Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Hatcher, R. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Hoshina, K. [Univ. of Wisconsin, Madison, WI (United States). Dept. of Physics. Wisconsin IceCube Particle Astrophysics Center; Liu, J. [College of William and Mary, Williamsburg, VA (United States). Dept. of Physics; Mahn, K. [Michigan State Univ., East Lansing, MI (United States). Dept. of Physics and Astronomy; Marshall, C. [Univ. of Rochester, NY (United States). Dept. of Physics; Morrison, J. [Michigan State Univ., East Lansing, MI (United States). Dept. of Physics and Astronomy; Nirkko, M. [Univ. of Bern (Switzerland). Albert Einstein Center for Fundamental Physics. Lab. for High Energy Physics (LHEP); Nowak, J. [Lancaster Univ. (United Kingdom). Dept. of Physics; Perdue, G. N. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Yarba, J. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)

    2015-12-25

    GENIE is a neutrino Monte Carlo event generator that simulates the primary interaction of a neutrino with a nuclear target, along with the subsequent propagation of the reaction products through the nuclear medium. It additionally contains libraries for fully-featured detector geometries and for managing various types of neutrino flux. This note details recent updates to GENIE, in particular, changes introduced into the newest production release, version 2.10.0.

  15. GENIE Production Release 2.10.0

    International Nuclear Information System (INIS)

    Alam, M.; Athar, M.; Hatcher, R.; Hoshina, K.; Nowak, J.; Yarba, J.

    2015-01-01

    GENIE is a neutrino Monte Carlo event generator that simulates the primary interaction of a neutrino with a nuclear target, along with the subsequent propagation of the reaction products through the nuclear medium. It additionally contains libraries for fully-featured detector geometries and for managing various types of neutrino flux. This note details recent updates to GENIE, in particular, changes introduced into the newest production release, version 2.10.0.

  16. Kinetics of drug release from ointments: Role of transient-boundary layer.

    Science.gov (United States)

    Xu, Xiaoming; Al-Ghabeish, Manar; Krishnaiah, Yellela S R; Rahman, Ziyaur; Khan, Mansoor A

    2015-10-15

    In the current work, an in vitro release testing method suitable for ointment formulations was developed using acyclovir as a model drug. Release studies were carried out using enhancer cells on acyclovir ointments prepared with oleaginous, absorption, and water-soluble bases. Kinetics and mechanism of drug release was found to be highly dependent on the type of ointment bases. In oleaginous bases, drug release followed a unique logarithmic-time dependent profile; in both absorption and water-soluble bases, drug release exhibited linearity with respect to square root of time (Higuchi model) albeit differences in the overall release profile. To help understand the underlying cause of logarithmic-time dependency of drug release, a novel transient-boundary hypothesis was proposed, verified, and compared to Higuchi theory. Furthermore, impact of drug solubility (under various pH conditions) and temperature on drug release were assessed. Additionally, conditions under which deviations from logarithmic-time drug release kinetics occur were determined using in situ UV fiber-optics. Overall, the results suggest that for oleaginous ointments containing dispersed drug particles, kinetics and mechanism of drug release is controlled by expansion of transient boundary layer, and drug release increases linearly with respect to logarithmic time. Published by Elsevier B.V.

  17. Kinetics of piroxicam release from low-methylated pectin/zein hydrogel microspheres

    Science.gov (United States)

    The kinetics of a model drug (piroxicam) release from pectin/zein hydrogel microspheres was studied under conditions simulating the gastrointestinal tract. It is established that the rate-limiting step in the release mechanism is drug diffusion out of the microspheres rather than its dissolution. ...

  18. Equilibrium and kinetic models for colloid release under transient solution chemistry conditions

    Science.gov (United States)

    We present continuum models to describe colloid release in the subsurface during transient physicochemical conditions. Our modeling approach relates the amount of colloid release to changes in the fraction of the solid surface area that contributes to retention. Equilibrium, kinetic, equilibrium and...

  19. Comparative assessment of in vitro release kinetics of calcitonin polypeptide from biodegradable microspheres.

    Science.gov (United States)

    Prabhu, Sunil; Sullivan, Jennifer L; Betageri, Guru V

    2002-01-01

    The objective of our study was to compare the in vitro release kinetics of a sustained-release injectable microsphere formulation of the polypeptide drug, calcitonin (CT), to optimize the characteristics of drug release from poly-(lactide-co-glycolide) (PLGA) copolymer biodegradable microspheres. A modified solvent evaporation and double emulsion technique was used to prepare the microspheres. Release kinetic studies were carried out in silanized tubes and dialysis bags, whereby microspheres were suspended and incubated in phosphate buffered saline, sampled at fixed intervals, and analyzed for drug content using a modified Lowry protein assay procedure. An initial burst was observed whereby about 50% of the total dose of the drug was released from the microspheres within 24 hr and 75% within 3 days. This was followed by a period of slow release over a period of 3 weeks in which another 10-15% of drug was released. Drug release from the dialysis bags was more gradual, and 50% CT was released only after 4 days and 75% after 12 days of release. Scanning electron micrographs revealed spherical particles with channel-like structures and a porous surface after being suspended in an aqueous solution for 5 days. Differential scanning calorimetric studies revealed that CT was present as a mix of amorphous and crystalline forms within the microspheres. Overall, these studies demonstrated that sustained release of CT from PLGA microspheres over a 3-week period is feasible and that release of drug from dialysis bags was more predictable than from tubes.

  20. Pore geometry of ceramic device: The key factor of drug release kinetics

    Directory of Open Access Journals (Sweden)

    Čolović B.

    2013-01-01

    Full Text Available Release kinetics of tigecycline, a potential antibiotic in treatment of osteomyelitis, from calcium hydroxyapatite (CHA, as one of the most important ceramic materials in bone tissue engineering, was investigated in this study. Tigecycline, in solid state, was mixed with CHA powder and the obtained mixture was compressed into tablets using two different pressures. These tablets were immersed in a phosphate-buffered saline solution and tigecycline release was measured by a UV-VIS spectrophotometer. The total release time was 5 or 28 days, depending on the pressure applied during compression. It was shown that there is a close relationship between pore sizes and drug release rate. The drug release kinetics was interpreted on the base of pore sizes and pore size distribution. [Projekat Ministarstva nauke Republike Srbije, br. 172026

  1. In vitro release kinetics of Tolmetin from tabletted Eudragit microparticles.

    Science.gov (United States)

    Pignatello, R; Consoli, P; Puglisi, G

    2000-01-01

    In a previous paper the preparation has been described, by three different techniques, of microparticles made of Eudragit RS 100 and RL 100 containing a NSAI agent, Tolmetin. Freely flowing microparticles failed to affect significantly the in vitro drug release, which displayed a similar dissolution profile after micro-encapsulation to the free drug powder. Microparticles were then converted into tablets and the effect of compression on drug delivery, as well as that of the presence of co-additives, was studied in the present work. Furthermore, microparticles were also prepared by adding MgO to the polymer matrix, to reduce the sensitivity of the drug to pH changes during its dissolution. Similarly, magnesium stearate was also used for microparticle formation as a droplet stabilizer, in order to reduce particle size and hinder rapid drug release. A mathematical evaluation, by using two semi-empirical equations, was applied to evaluate the influence of dissolution and diffusion phenomena upon drug release from microparticle tablets.

  2. Drug kinetics release from Eudragit – Tenofovir@SiOC tablets

    Energy Technology Data Exchange (ETDEWEB)

    Tamayo, A., E-mail: aitanath@icv.csic.es [Ceramics and Glass Institute, CSIC, Madrid (Spain); Mazo, M.A. [Ceramics and Glass Institute, CSIC, Madrid (Spain); Veiga, M.D.; Ruiz-Caro, R.; Notario-Pérez, F. [Dpt. Pharmaceutical Technology, Faculty of Pharmacy, Complutense University of Madrid, Madrid (Spain); Rubio, J. [Ceramics and Glass Institute, CSIC, Madrid (Spain)

    2017-06-01

    A novel drug release system has been obtained in form of tablets from Eudragit® RS and tenofovir loaded on porous silicon oxycarbide glasses (SiOC). Active carbon (AC) and mesoporous silica (MCM-41) have also been used for comparative purposes. The porous silicon oxycarbide presents a bimodal mesopore size distribution that is maintained after functionalization with amino groups. We have studied the adsorption kinetics and adsorption equilibrium when the materials are loaded with tenofovir and, in all cases, pseudo-second order kinetics and Langmuir isotherm have been revealed as the most representative models describing the kinetic and thermodynamic parameters. Besides, the tenofovir adsorption on these materials turns out to be a favorable process. In vitro release of tenofovir has been studied in simulated vaginal medium by applying different release models. Continuous tenofovir release for > 20 days has been obtained for the SiOC material functionalized with amine groups. We concluded that the drug release occurs in two steps that involve a drug diffusion step through the material pores and diffusion through the swollen polymer. The interactions between the tenofovir drug and de amine groups of the functionalized silicon oxycarbide also play an important role in the release process. - Highlights: • Kinetic and thermodinamic parameters of the adsorption of tenofovir on porous substrates have been obtained. • Sustained release of TFV for > 20 days in SVF when it is supported on SiOC and manufactured as Eudragit®RS-containing tablets. • Release described by a two-step process involving diffusion through SiOC matrix and subsequent diffusion through the polymer.

  3. The release behavior and kinetic evaluation of tramadol HCl from chemically cross linked Ter polymeric hydrogels.

    Science.gov (United States)

    Malana, Muhammad A; Zohra, Rubab

    2013-01-18

    Hydrogels, being stimuli responsive are considered to be effective for targeted and sustained drug delivery. The main purpose for this work was to study the release behavior and kinetic evaluation of Tramadol HCl from chemically cross linked ter polymeric hydrogels. Ter-polymers of methacrylate, vinyl acetate and acrylic acid cross linked with ethylene glycol dimethacrylate (EGDMA) were prepared by free radical polymerization. The drug release rates, dynamic swelling behavior and pH sensitivity of hydrogels ranging in composition from 1-10 mol% EGDMA were studied. Tramadol HCl was used as model drug substance. The release behavior was investigated at pH 8 where all formulations exhibited non-Fickian diffusion mechanism. Absorbency was found to be more than 99% indicating good drug loading capability of these hydrogels towards the selected drug substance. Formulations designed with increasing amounts of EGDMA had a decreased equilibrium media content as well as media penetrating velocity and thus exhibited a slower drug release rate. Fitting of release data to different kinetic models indicate that the kinetic order shifts from the first to zero order as the concentration of drug was increased in the medium, showing gradual independency of drug release towards its concentration. Formulations with low drug content showed best fitness with Higuchi model whereas those with higher concentration of drug followed Hixson-Crowell model with better correlation values indicating that the drug release from these formulations depends more on change in surface area and diameter of tablets than that on concentration of the drug. Release exponent (n) derived from Korse-Meyer Peppas equation implied that the release of Tramadol HCl from these formulations was generally non-Fickian (n > 0.5 > 1) showing swelling controlled mechanism. The mechanical strength and controlled release capability of the systems indicate that these co-polymeric hydrogels have a great potential to

  4. Fission product release from SLOWPOKE-2 reactors

    Energy Technology Data Exchange (ETDEWEB)

    Harnden-Gillis, A M.C. [Queen` s Univ., Kingston, ON (Canada). Dept. of Physics

    1994-12-31

    Increasing radiation fields at several SLOWPOKE-2 reactors fuelled with highly enriched uranium aluminum alloy fuel have begun to interfere with the daily operation of these reactors. To investigate this phenomenon, samples of reactor container water and gas from the headspace were obtained at four SLOWPOKE-2 reactor facilities and examined by gamma ray spectroscopy methods. These radiation fields are due to the circulation of fission products within the reactor container vessel. The most likely source of the fission product release is an area of uranium-bearing material exposed to the coolant at the end weld line which originated at the time of fuel fabrication. The results of this study are compared with observations from an underwater visual examination of one core and the metallographic examination of archived fuel elements. 19 refs., 4 tabs., 8 figs.

  5. A prominent anchoring effect on the kinetic control of drug release from mesoporous silica nanoparticles (MSNs).

    Science.gov (United States)

    Tran, Vy Anh; Lee, Sang-Wha

    2018-01-15

    This work demonstrated kinetically controlled release of model drugs (ibuprofen, FITC) from well-tailored mesoporous silica nanoparticles (MSNs) depending on the surface charges and molecular sizes of the drugs. The molecular interactions between entrapped drugs and the pore walls of MSNs controlled the release of the drugs through the pore channels of MSNs. Also, polydopamine (PDA) layer-coated MSNs (MSNs@PDA) was quite effective to retard the release of large FITC, in contrast to a slight retardation effect on relatively small Ibuprofen. Of all things, FITC (Fluorescein isothiocyanate)-labeled APTMS (3-aminopropyltrimethoxysilane) (APTMS-FITC conjugates) grafted onto the MSNs generate a pinch-effect on the pore channel (so-called a prominent anchoring effect), which was highly effective in trapping (or blocking) drug molecules at the pore mouth of the MSNs. The anchored APTMS-FITC conjugates provided not only tortuous pathways to the diffusing molecules, but also sustained release of the ibuprofen over a long period of time (∼7days). The fast release kinetics was predicted by an exponential equation based on Fick's law, while the slow release kinetics was predicted by Higuchi model. Copyright © 2017 Elsevier Inc. All rights reserved.

  6. Release kinetics of tocopherol and quercetin from binary antioxidant controlled-release packaging films.

    Science.gov (United States)

    Chen, Xi; Lee, Dong Sun; Zhu, Xuntao; Yam, Kit L

    2012-04-04

    This paper investigated the feasibility of manipulating packaging polymers with various degrees of hydrophobicity to release two antioxidants, tocopherol and quercetin, at rates suitable for long-term inhibition of lipid oxidation in food. For example, one antioxidant can be released at a fast rate to provide short-term/intermediate protection, whereas the other antioxidant can be released at a slower rate to provide intermediate/long-term protection of lipid oxidation. Controlled-release packaging films containing tocopherol and quercetin were produced using ethylene vinyl alcohol (EVOH), ethylene vinyl acetate (EVA), low-density polyethylene (LDPE), and polypropylene (PP) polymers; the release of these antioxidants to 95% ethanol (a fatty food simulant) was measured using UV-vis spectrophotometry, and Fickian diffusion models with appropriate initial and boundary conditions were used to fit the data. For films containing only quercetin, the results show that the release of quercetin was much faster but lasted for a much shorter time for hydrophilic polymers (EVOH and EVA) than for hydrophobic polymers (LDPE and PP). For binary antioxidant films containing tocopherol and quercetin, the results show that tocopherol released more rapidly but for a shorter period of time than quercetin in LDPE and EVOH films, and the difference is more pronounced for LDPE films than EVOH films. The results also show the presence of tocopherol can accelerate the release of quercetin. Although none of the films produced is acceptable for long-term lipid oxidation inhibition, the study provides encouraging results suggesting that acceptable films may be produced in the future using polymer blend films.

  7. Controlled release system for ametryn using polymer microspheres: Preparation, characterization and release kinetics in water

    International Nuclear Information System (INIS)

    Grillo, Renato; Pereira, Anderson do Espirito Santo; Ferreira Silva de Melo, Nathalie; Porto, Raquel Martins; Feitosa, Leandro Oliveira; Tonello, Paulo Sergio; Dias Filho, Newton L.; Rosa, Andre Henrique; Lima, Renata; Fraceto, Leonardo Fernandes

    2011-01-01

    The purpose of this work was to develop a modified release system for the herbicide ametryn by encapsulating the active substance in biodegradable polymer microparticles produced using the polymers poly(hydroxybutyrate) (PHB) or poly(hydroxybutyrate-valerate) (PHBV), in order to both improve the herbicidal action and reduce environmental toxicity. PHB or PHBV microparticles containing ametryn were prepared and the efficiencies of herbicide association and loading were evaluated, presenting similar values of approximately 40%. The microparticles were characterized by scanning electron microscopy (SEM), which showed that the average sizes of the PHB and PHBV microparticles were 5.92 ± 0.74 μm and 5.63 ± 0.68 μm, respectively. The ametryn release profile was modified when it was encapsulated in the microparticles, with slower and more sustained release compared to the release profile of pure ametryn. When ametryn was associated with the PHB and PHBV microparticles, the amount of herbicide released in the same period of time was significantly reduced, declining to 75% and 87%, respectively. For both types of microparticle (PHB and PHBV) the release of ametryn was by diffusion processes due to anomalous transport (governed by diffusion and relaxation of the polymer chains), which did not follow Fick's laws of diffusion. The results presented in this paper are promising, in view of the successful encapsulation of ametryn in PHB or PHBV polymer microparticles, and indications that this system may help reduce the impacts caused by the herbicide, making it an environmentally safer alternative.

  8. Temporal measurements and kinetics of selenium release during coal combustion and gasification in a fluidized bed

    International Nuclear Information System (INIS)

    Shen, Fenghua; Liu, Jing; Zhang, Zhen; Yang, Yingju

    2016-01-01

    Highlights: • The temporal release of Se from coal combustion and gasification was measured. • Kinetic laws for Se release from coal combustion and gasification were determined. • The influences of temperature and chemical composition of flue gas were clarified. • The interactions of Se species with mineral affect the release kinetics of Se. - Abstract: The temporal release of selenium from coal during combustion and gasification in a fluidized bed was measured in situ by an on-line analysis system of trace elements in flue gas. The on-line analysis system is based on an inductively coupled plasma optical emission spectroscopy (ICP-OES), and can measure concentrations of trace elements in flue gas quantitatively and continuously. The results of on-line analysis suggest that the concentration of selenium in flue gas during coal gasification is higher than that during coal combustion. Based on the results of on-line analysis, a second-order kinetic law r(x) = 0.94e −26.58/RT (−0.56 x 2 −0.51 x + 1.05) was determined for selenium release during coal combustion, and r(x) = 11.96e −45.03/RT (−0.53 x 2 −0.56 x + 1.09) for selenium release during coal gasification. These two kinetic laws can predict respectively the temporal release of selenium during coal combustion and gasification with an acceptable accuracy. Thermodynamic calculations were conducted to predict selenium species during coal combustion and gasification. The speciation of selenium in flue gas during coal combustion differs from that during coal gasification, indicating that selenium volatilization is different. The gaseous selenium species can react with CaO during coal combustion, but it is not likely to interact with mineral during coal gasification.

  9. Equilibrium and kinetic models for colloid release under transient solution chemistry conditions.

    Science.gov (United States)

    Bradford, Scott A; Torkzaban, Saeed; Leij, Feike; Simunek, Jiri

    2015-10-01

    We present continuum models to describe colloid release in the subsurface during transient physicochemical conditions. Our modeling approach relates the amount of colloid release to changes in the fraction of the solid surface area that contributes to retention. Equilibrium, kinetic, equilibrium and kinetic, and two-site kinetic models were developed to describe various rates of colloid release. These models were subsequently applied to experimental colloid release datasets to investigate the influence of variations in ionic strength (IS), pH, cation exchange, colloid size, and water velocity on release. Various combinations of equilibrium and/or kinetic release models were needed to describe the experimental data depending on the transient conditions and colloid type. Release of Escherichia coli D21g was promoted by a decrease in solution IS and an increase in pH, similar to expected trends for a reduction in the secondary minimum and nanoscale chemical heterogeneity. The retention and release of 20nm carboxyl modified latex nanoparticles (NPs) were demonstrated to be more sensitive to the presence of Ca(2+) than D21g. Specifically, retention of NPs was greater than D21g in the presence of 2mM CaCl2 solution, and release of NPs only occurred after exchange of Ca(2+) by Na(+) and then a reduction in the solution IS. These findings highlight the limitations of conventional interaction energy calculations to describe colloid retention and release, and point to the need to consider other interactions (e.g., Born, steric, and/or hydration forces) and/or nanoscale heterogeneity. Temporal changes in the water velocity did not have a large influence on the release of D21g for the examined conditions. This insensitivity was likely due to factors that reduce the applied hydrodynamic torque and/or increase the resisting adhesive torque; e.g., macroscopic roughness and grain-grain contacts. Our analysis and models improve our understanding and ability to describe the amounts

  10. Releasable Kinetic Energy-Based Inertial Control of a DFIG Wind Power Plant

    DEFF Research Database (Denmark)

    Lee, Jinsik; Muljadi, Eduard; Sørensen, Poul Ejnar

    2016-01-01

    Wind turbine generators (WTGs) in a wind power plant (WPP) contain different levels of releasable kinetic energy (KE) because of the wake effects. This paper proposes a releasable KE-based inertial control scheme for a doubly fed induction generator (DFIG) WPP that differentiates the contributions....... The proposed scheme adjusts the two loop gains in a DFIG controller depending on its rotor speed so that a DFIG operating at a higher rotor speed releases more KE. The performance of the proposed scheme was investigated under various wind conditions. The results clearly indicate that the proposed scheme...

  11. Release kinetics and cell viability of ibuprofen nanocrystals produced by melt-emulsification.

    Science.gov (United States)

    Fernandes, A R; Dias-Ferreira, J; Cabral, C; Garcia, M L; Souto, E B

    2018-06-01

    The clinical use of poorly water-soluble drugs has become a big challenge in pharmaceutical development due to the compromised bioavailability of the drugs in vivo. Nanocrystals have been proposed as a formulation strategy to improve the dissolution properties of these drugs. The benefits of using nanocrystals in drug delivery, when compared to other nanoparticles, are related to their production facilities, simple structure, and suitability for a variety of administration routes. High pressure homogenization (HPH) is the most promising production process, which can be employed at low or high temperatures. Ibuprofen nanocrystals with a mean size below 175 nm, and polydispersity below 0.18, have been produced by melt-emulsification, followed by HPH. Two nanocrystal formulations, differing on the surfactant composition, have been produced, their in vitro ibuprofen release tested in Franz diffusion cells and adjusted to several kinetic models (zero order, first order, Higuchi, Hixson-Crowell, Korsmeyer-Peppas, Baker-Lonsdale and Weibull model). Cell viability was assessed at 3, 6 and 24 h of incubation on human epithelial colorectal cells (Caco-2) by AlamarBlue ® colorimetric assay. For both formulations, Caco-2 cells viability was dependent on the drug concentration and time of exposure. Copyright © 2018 Elsevier B.V. All rights reserved.

  12. Zinc and Copper Release Kinetics in a Calcareous Soil amended with Manure and Vermicompost

    Directory of Open Access Journals (Sweden)

    hamid reza motaghian

    2017-02-01

    Full Text Available Introduction: Use of organic fertilizers such as vermicompost in agricultural soils with low organic matter content is almost considered as a one way for adding nutrients in these soils. However, application of these fertilizers may affect micronutrient release characteristics. Micronutrient release Kinetics in soils especially in amended soils give information about potential of amended soils to release these elements into solution. Although it is important to study kinetics of micronutrient release from soils to identify soil micronutrients buffering capacity, little attention has been paid to micronutrients desorption rate studies especially in amended soils. The rate of release micronutrients from soil solid phase by considering micronutrients as adsorbed ions or in mineral forms is an important parameter in nutrition of plants by microelements and a dynamic factor that regulates its continuous supply to growing plants; nonetheless, little attention has been paid to micronutrients kinetics inrelease studies. Material and Methods: In this study, kinetics of zinc (Zn and copper (Cu were compared in one calcareous soil amended with 0, 0.5, and 1% (w/w of manure and vermicompost in a completely randomized design and then amended and un-amended soils were incubated at field capacity, for 30 days. After incubation period, amended and un-amended soils were air-dried and were prepared to kinetics study. Kinetics of Zn and Cu release were studied by successive extraction with DTPA-TEA solution. Two grams of the amended and un-amended soils, in triplicate, suspended in 20 ml DTPA-TEA solution were equilibrated at 25±10C for 1, 8, 24, 48, 72, 96, 120, 144, 168, 336 and 504 h by shaking for 15 min. before incubation and 15 min. before the suspensions were centrifuged. Seven drops of toluene were added to each 1000 ml of extractant to inhibit microbial activity. Zinc and copper desorption with time was fitted by using different equations (Zero

  13. The total kinetic energy release in the fast neutron-induced fission of {sup 232}Th

    Energy Technology Data Exchange (ETDEWEB)

    King, Jonathan; Yanez, Ricardo; Loveland, Walter; Barrett, J. Spencer; Oscar, Breland [Oregon State University, Dept. of Chemistry, Corvallis, OR (United States); Fotiades, Nikolaos; Tovesson, Fredrik; Young Lee, Hye [Los Alamos National Laboratory, Physics Division, Los Alamos, NM (United States)

    2017-12-15

    The post-emission total kinetic energy release (TKE) in the neutron-induced fission of {sup 232}Th was measured (using white spectrum neutrons from LANSCE) for neutron energies from E{sub n} = 3 to 91 MeV. In this energy range the average post-neutron total kinetic energy release decreases from 162.3 ± 0.3 at E{sub n} = 3 MeV to 154.9 ± 0.3 MeV at E{sub n} = 91 MeV. Analysis of the fission mass distributions indicates that the decrease in TKE with increasing neutron energy is a combination of increasing yields of symmetric fission (which has a lower associated TKE) and a decrease in the TKE release in asymmetric fission. (orig.)

  14. Core degradation and fission product release

    International Nuclear Information System (INIS)

    Wright, R.W.; Hagen, S.J.L.

    1992-01-01

    Experiments on core degradation and melt progression in severe LWR accidents have provided reasonable understanding of the principal processes involved in the early phase of melt progression that extends through core degradation and metallic material melting and relocation. A general but not a quantitative understanding of late phase melt progression that involves ceramic material melting and relocation has also been obtained, primarily from the TMI-2 core examination. A summary is given of the current state of knowledge on core degradation and melt progression obtained from these integral experiments and of the principal remaining significant uncertainties. A summary is also given of the principal results on in-vessel fission product release obtained from these experiments. (author). 8 refs, 5 figs, 3 tabs

  15. Effect of surfactant chain length on drug release kinetics from microemulsion-laden contact lenses.

    Science.gov (United States)

    Maulvi, Furqan A; Desai, Ankita R; Choksi, Harsh H; Patil, Rahul J; Ranch, Ketan M; Vyas, Bhavin A; Shah, Dinesh O

    2017-05-30

    The effect of surfactant chain lengths [sodium caprylate (C 8 ), Tween 20 (C 12 ), Tween 80 (C 18 )] and the molecular weight of block copolymers [Pluronic F68 and Pluronic F 127] were studied to determine the stability of the microemulsion and its effect on release kinetics from cyclosporine-loaded microemulsion-laden hydrogel contact lenses in this work. Globule size and dilution tests (transmittance) suggested that the stability of the microemulsion increases with increase in the carbon chain lengths of surfactants and the molecular weight of pluronics. The optical transmittance of direct drug-laden contact lenses [DL-100] was low due to the precipitation of hydrophobic drugs in the lenses, while in microemulsion-laden lenses, the transmittance was improved when stability of the microemulsion was achieved. The results of in vitro release kinetics revealed that drug release was sustained to a greater extent as the stability of microemulsion was improved as well. This was evident in batch PF127-T80, which showed sustained release for 15days in comparison to batch DL-100, which showed release up to 7days. An in vivo drug release study in rabbit tear fluid showed significant increase in mean residence time (MRT) and area under curve (AUC) with PF-127-T80 lenses (stable microemulsion) in comparison to PF-68-SC lenses (unstable microemulsion) and DL-100 lenses. This study revealed the correlation between the stability of microemulsion and the release kinetics of drugs from contact lenses. Thus, it was inferred that the stable microemulsion batches sustained the release of hydrophobic drugs, such as cyclosporine from contact lenses for an extended period of time without altering critical lens properties. Copyright © 2017 Elsevier B.V. All rights reserved.

  16. The release of fission products from uranium metal: a review

    International Nuclear Information System (INIS)

    Minshall, P.C.

    1989-03-01

    The literature on the release of fission products as gaseous species from irradiated uranium metal in oxidising atmospheres has been reviewed. Release of actinides and of fission products as spalled particulate were not considered. Data is given on the release in air, carbon dioxide, steam and mixtures of steam and air. The majority of data discussed lie between 800 and 1200 0 C though some results for xenon, krypton and iodine releases below 800 0 C are given. Two measures of fission product release are discussed: the release fraction, F(tot), which is the ratio of the total release to the initial inventory, and the fractional release, F(ox), which is the fraction released from the oxidised metal. The effect of burn-up, atmosphere and temperature on F(tot) and F(ox) is examined and the conditions under which the release fraction, F(tot) is proportional to the extent of oxidation discussed. (author)

  17. Layered double hydroxide using hydrothermal treatment: morphology evolution, intercalation and release kinetics of diclofenac sodium

    Institute of Scientific and Technical Information of China (English)

    Mathew JOY; Srividhya J.IYENGAR; Jui CHAKRABORTY; Swapankumar GHOSH

    2017-01-01

    The present work demonstrates the possibilities of hydrothermal transformation of Zn-AI layered double hydroxide (LDH) nanostructure by varying the synthetic conditions.The manipulation in washing step before hydrothermal treatment allows control over crystal morphologies,size and stability of their aqueous solutions.We examined the crystal growth process in the presence and the absence of extra ions during hydrothermal treatment and its dependence on the drug (diclofenac sodium (DicNa)) loading and release processes.Hexagonal plate-like crystals show sustained release with ~90% of the drug from the matrix in a week,suggesting the applicability of LDH nanohybrids in sustained drug delivery systems.The fits to the release kinetics data indicated the drug release as a diffusion-controlled release process.LDH with rod-like morphology shows excellent colloidal stability in aqueous suspension,as studied by photon correlation spectroscopy.

  18. Layered double hydroxide using hydrothermal treatment: morphology evolution, intercalation and release kinetics of diclofenac sodium

    Science.gov (United States)

    Joy, Mathew; Iyengar, Srividhya J.; Chakraborty, Jui; Ghosh, Swapankumar

    2017-12-01

    The present work demonstrates the possibilities of hydrothermal transformation of Zn-Al layered double hydroxide (LDH) nanostructure by varying the synthetic conditions. The manipulation in washing step before hydrothermal treatment allows control over crystal morphologies, size and stability of their aqueous solutions. We examined the crystal growth process in the presence and the absence of extra ions during hydrothermal treatment and its dependence on the drug (diclofenac sodium (Dic-Na)) loading and release processes. Hexagonal plate-like crystals show sustained release with ˜90% of the drug from the matrix in a week, suggesting the applicability of LDH nanohybrids in sustained drug delivery systems. The fits to the release kinetics data indicated the drug release as a diffusion-controlled release process. LDH with rod-like morphology shows excellent colloidal stability in aqueous suspension, as studied by photon correlation spectroscopy.

  19. Encapsulation of naproxen in lipid-based matrix microspheres: characterization and release kinetics.

    Science.gov (United States)

    Bhoyar, P K; Morani, D O; Biyani, D M; Umekar, M J; Mahure, J G; Amgaonkar, Y M

    2011-04-01

    The objective of this study was to microencapsulate the anti-inflammatory drug (naproxen) to provide controlled release and minimizing or eliminating local side effect by avoiding the drug release in the upper gastrointestinal track. Naproxen was microencapsulated with lipid-like carnauba wax, hydrogenated castor oil using modified melt dispersion (modified congealable disperse phase encapsulation) technique. Effect of various formulation and process variables such as drug-lipid ratio, concentration of modifier, concentration of dispersant, stirring speed, stirring time, temperature of external phase, on evaluatory parameters such as size, entrapment efficiency, and in vitro release of naproxen were studied. The microspheres were characterized for particle size, scanning electron microscopy (SEM), FT-IR spectroscopy, drug entrapment efficiency, in vitro release studies, for in vitro release kinetics. The shape of microspheres was found to be spherical by SEM. The drug entrapment efficiency of various batches of microspheres was found to be ranging from 60 to 90 %w/w. In vitro drug release studies were carried out up to 24 h in pH 7.4 phosphate buffer showing 50-65% drug release. In vitro drug release from all the batches showed better fitting with the Korsmeyer-Peppas model, indicating the possible mechanism of drug release to be by diffusion and erosion of the lipid matrix.

  20. Reaction dynamics of the four-centered elimination CH2OH + --> CHO + +H2: Measurement of kinetic energy release distribution and classical trajectory calculation

    Science.gov (United States)

    Lee, Tae Geol; Park, Seung C.; Kim, Myung Soo

    1996-03-01

    Mass-analyzed ion kinetic energy (MIKE) spectrum of CHO+ generated in the unimolecular dissociation of CH2OH+ was measured. Kinetic energy release distribution (KERD) was evaluated by analyzing the spectrum according to the algorithm developed previously. The average kinetic energy release evaluated from the distribution was extraordinarily large, 1.63 eV, corresponding to 75% of the reverse barrier of the reaction. A global analytical potential energy surface was constructed such that the experimental energetics was represented and that various features in the ab initio potential energy surface were closely reproduced. Classical trajectory calculation was carried out with the global analytical potential energy surface to investigate the causes for the extraordinarily large kinetic energy release. Based on the detailed dynamical calculations, it was found that the strained bending forces at the transition state and strengthening of the CO bond from double to triple bond character were mainly responsible for such a significant kinetic energy release. In addition, the dissociation products H2 and CHO+ ion were found to be rotationally excited in the trajectory calculations. This was attributed to the asymmetry of the transition state and the release of asymmetric bending forces. Also, the bending vibrational modes of CHO+ and the H2 stretching mode, which are coupled with the bending coordinates, were found to be moderately excited.

  1. How Monte Carlo heuristics aid to identify the physical processes of drug release kinetics.

    Science.gov (United States)

    Lecca, Paola

    2018-01-01

    We implement a Monte Carlo heuristic algorithm to model drug release from a solid dosage form. We show that with Monte Carlo simulations it is possible to identify and explain the causes of the unsatisfactory predictive power of current drug release models. It is well known that the power-law, the exponential models, as well as those derived from or inspired by them accurately reproduce only the first 60% of the release curve of a drug from a dosage form. In this study, by using Monte Carlo simulation approaches, we show that these models fit quite accurately almost the entire release profile when the release kinetics is not governed by the coexistence of different physico-chemical mechanisms. We show that the accuracy of the traditional models are comparable with those of Monte Carlo heuristics when these heuristics approximate and oversimply the phenomenology of drug release. This observation suggests to develop and use novel Monte Carlo simulation heuristics able to describe the complexity of the release kinetics, and consequently to generate data more similar to those observed in real experiments. Implementing Monte Carlo simulation heuristics of the drug release phenomenology may be much straightforward and efficient than hypothesizing and implementing from scratch complex mathematical models of the physical processes involved in drug release. Identifying and understanding through simulation heuristics what processes of this phenomenology reproduce the observed data and then formalize them in mathematics may allow avoiding time-consuming, trial-error based regression procedures. Three bullet points, highlighting the customization of the procedure. •An efficient heuristics based on Monte Carlo methods for simulating drug release from solid dosage form encodes is presented. It specifies the model of the physical process in a simple but accurate way in the formula of the Monte Carlo Micro Step (MCS) time interval.•Given the experimentally observed curve of

  2. Kinetics of Brominated Flame Retardant (BFR) Releases from Granules of Waste Plastics.

    Science.gov (United States)

    Sun, Bingbing; Hu, Yuanan; Cheng, Hefa; Tao, Shu

    2016-12-20

    Plastic components of e-waste contain high levels of brominated flame retardants (BFRs), whose releases cause environmental and human health concerns. This study characterized the release kinetics of polybrominated diphenyl ethers (PBDEs) from millimeter-sized granules processed from the plastic exteriors of two scrap computer displays at environmentally relevant temperatures. The release rate of a substitute of PBDEs, 1,2-bis(2,4,6-tribromophenoxy)ethane (BTBPE), from the waste plastics, was reported for the first time. Deca-BDE was the most abundant PBDE congeners in both materials (87-89%), while BTBPE was also present at relatively high contents. The release kinetics of BFRs could be modeled as one-dimensional diffusion, while the temperature dependence of diffusion coefficients was well described by the Arrhenius equation. The diffusion coefficients of BFRs (at 30 °C) in the plastic matrices were estimated to be in the range of 10 -27.16 to 10 -19.96 m 2 ·s -1 , with apparent activation energies between 88.4 and 154.2 kJ·mol -1 . The half-lives of BFR releases (i.e., 50% depletion) from the plastic granules ranged from thousands to tens of billions of years at ambient temperatures. These findings suggest that BFRs are released very slowly from the matrices of waste plastics through molecular diffusion, while their emissions can be significantly enhanced with wear-and-tear and pulverization.

  3. Fuel and fission product release from sodium

    International Nuclear Information System (INIS)

    Sauter, H.

    1992-01-01

    The NALA program at Kernforschungszentrum Karlsruhe is concerned with the release of fuel and fission products from hot or boiling sodium pools (radiological secondary source term) in a liquid-metal fast breeder reactor accident scenario with tank failure. The main concern is to determine retention factors (RF), to uncover the most essential parameters that influence the RF values, and to describe the way they do it. In the framework of the last NALA series, NALA IIIc, the influence of sodium-concrete interaction was investigated, partly with subsequent sodium burning. In our experiments, ∼3 kg of sodium and added pieces of concrete reaching from 4 to 40 g was used. The composition of the concrete was suitable for shielding and construction as used in the SNR-300 reactor. Fuel was simulated by 20-μm particles of depleted UO 2 , and CeO 2 , NaI, and TeO 2 were used as fission products. Most experiments were performed in an inert argon gas atmosphere with monitored hydrogen development. In some cases, the preheated pool was allowed to come into contact with ambient air, which caused an ordinary sodium fire. For the latter case, we used the 220-m 3 FAUNA vessel as an outer containment and collected the fire aerosols by a trap and subsequent filters for analysis

  4. Implementation of a new gamma spectrometer on the MERARG loop: Application to the volatile fission products release measurement

    Energy Technology Data Exchange (ETDEWEB)

    Bernard, S.; Gleizes, B.; Pontillon, Y.; Hanus, E.; Ducros, G. [CEA, DEN, DEC, SA3C, F-13108, Saint Paul lez Durance, (France); Roure, C. [CEA, DEN, DTN, SMTA, F-13108, Saint Paul lez Durance, (France)

    2015-07-01

    The MERARG facility initially aims at the annealing of irradiated fuel samples to study the gaseous fission products release kinetics. In order to complete the evaluation of the source term potentially released during accidental situation, the MERARG experimental circuit has been enhanced with a new gamma spectrometer. This one is directly sighting the fuel and is devoted to the fission products release kinetics. Because of the specificities of the fuel measurements, it has been dimensioned and designed to match the specific requirements. The acquisition chain and the collimation system have been optimized for this purpose and a first set of two experiments have shown the good functioning of this new spectrometry facility. (authors)

  5. A Markov State-based Quantitative Kinetic Model of Sodium Release from the Dopamine Transporter

    Science.gov (United States)

    Razavi, Asghar M.; Khelashvili, George; Weinstein, Harel

    2017-01-01

    The dopamine transporter (DAT) belongs to the neurotransmitter:sodium symporter (NSS) family of membrane proteins that are responsible for reuptake of neurotransmitters from the synaptic cleft to terminate a neuronal signal and enable subsequent neurotransmitter release from the presynaptic neuron. The release of one sodium ion from the crystallographically determined sodium binding site Na2 had been identified as an initial step in the transport cycle which prepares the transporter for substrate translocation by stabilizing an inward-open conformation. We have constructed Markov State Models (MSMs) from extensive molecular dynamics simulations of human DAT (hDAT) to explore the mechanism of this sodium release. Our results quantify the release process triggered by hydration of the Na2 site that occurs concomitantly with a conformational transition from an outward-facing to an inward-facing state of the transporter. The kinetics of the release process are computed from the MSM, and transition path theory is used to identify the most probable sodium release pathways. An intermediate state is discovered on the sodium release pathway, and the results reveal the importance of various modes of interaction of the N-terminus of hDAT in controlling the pathways of release.

  6. Impact of IGF-I release kinetics on bone healing: a preliminary study in sheep.

    Science.gov (United States)

    Luginbuehl, Vera; Zoidis, Evangelos; Meinel, Lorenz; von Rechenberg, Brigitte; Gander, Bruno; Merkle, Hans P

    2013-09-01

    Spatiotemporal release of growth factors from a delivery device can profoundly affect the efficacy of bone growth induction. Here, we report on a delivery platform based on the encapsulation of insulin-like growth factor I (IGF-I) in different poly(D,L-lactide) (PLA) and poly(D,L-lactide-co-glycolide) (PLGA) microsphere (MS) formulations to control IGF-I release kinetics. In vitro IGF-I release profiles generally exhibited an initial burst (14-36% of total IGF-I content), which was followed by a more or less pronounced dormant phase with little release (2 to 34 days), and finally, a third phase of re-increased IGF-I release. The osteoinductive potential of these different IGF-I PL(G)A MS formulations was tested in studies using 8-mm metaphyseal drill hole bone defects in sheep. Histomorphometric analysis at 3 and 6 weeks after surgery showed that new bone formation was improved in the defects locally treated with IGF-I PL(G)A MS (n=5) as compared to defects filled with IGF-I-free PL(G)A MS (n=4). The extent of new bone formation was affected by the particular release kinetics, although a definitive relationship was not evident. Local administration of IGF-I resulted in down-regulation of inflammatory marker genes in all IGF-I treated defects. The over-expression of growth factor genes in response to IGF-I delivery was restricted to formulations that produced osteogenic responses. These experiments demonstrate the osteoinductive potential of sustained IGF-I delivery and show the importance of delivery kinetics for successful IGF-I-based therapies. Copyright © 2013 Elsevier B.V. All rights reserved.

  7. 5-Fluorouracil Encapsulated Chitosan Nanoparticles for pH-Stimulated Drug Delivery: Evaluation of Controlled Release Kinetics

    Directory of Open Access Journals (Sweden)

    R. Seda Tığlı Aydın

    2012-01-01

    Full Text Available Nanoparticles consisting of human therapeutic drugs are suggested as a promising strategy for targeted and localized drug delivery to tumor cells. In this study, 5-fluorouracil (5-FU encapsulated chitosan nanoparticles were prepared in order to investigate potentials of localized drug delivery for tumor environment due to pH sensitivity of chitosan nanoparticles. Optimization of chitosan and 5-FU encapsulated nanoparticles production revealed 148.8±1.1 nm and 243.1±17.9 nm particle size diameters with narrow size distributions, which are confirmed by scanning electron microscope (SEM images. The challenge was to investigate drug delivery of 5-FU encapsulated chitosan nanoparticles due to varied pH changes. To achieve this objective, pH sensitivity of prepared chitosan nanoparticle was evaluated and results showed a significant swelling response for pH 5 with particle diameter of ∼450 nm. In vitro release studies indicated a controlled and sustained release of 5-FU from chitosan nanoparticles with the release amounts of 29.1–60.8% due to varied pH environments after 408 h of the incubation period. pH sensitivity is confirmed by mathematical modeling of release kinetics since chitosan nanoparticles showed stimuli-induced release. Results suggested that 5-FU encapsulated chitosan nanoparticles can be launched as pH-responsive smart drug delivery agents for possible applications of cancer treatments.

  8. Digestion kinetics of carbohydrate fractions of citrus by-products

    DEFF Research Database (Denmark)

    Lashkari, Saman; Taghizadeh, Akbar

    2015-01-01

    The present experiment was carried out to determine the digestion kinetics of carbohydrate fractions of citrus by-products. Grapefruit pulp (GP), lemon pulp (LE), lime pulp (LI) and orange pulp (OP) were the test feed. Digestion kinetic of whole citrus by-products and neutral detergent fiber (NDF......) fraction and acid detergent fiber (ADF) fractions of citrus by-products were measured using the in vitro gas production technique. Fermentation kinetics of the neutral detergent soluble carbohydrates (NDSC) fraction and hemicelluloses were calculated using a curve subtraction. The fermentation rate...... of whole was the highest for the LE (p by-products lag time was longer for hemicellulose than other carbohydrate fractions. There was no significant difference among potential gas production (A) volumes of whole test feeds (p

  9. AIR POLLUTION FROM ANIMAL AND MUNICIPAL WASTEWATER: ASSESSMENT OF PRODUCTION AND RELEASE OF NOXIOUS GASES

    DEFF Research Database (Denmark)

    Dai, Xiaorong

    from animal manure (mixture of urine and feces) by hydrolysis of urinary urea catalyzed by microbial urease present in feces. To better understand the enzymatic process of ammonia formation in manure, experiments based on Michaelis-Menten kinetics were conducted to obtain accurate estimates...... of the kinetic parameters of urease activity of feces and manure from pig and cattle, and to investigate the effects of pH on animal fecal urease by individual ammonium generation rate determination at five pH levels. Investigating the gas production and release mechanisms is important not only for estimating...... characteristics of different types of wastes (e.g., the total nitrogen, total ammoniacal nitrogen, dry matter, and pH) had great influence on the releases of NH3, CO2, H2S, and SO2. The investigation of kinetic parameter showed that the maximum urease activity for pig feces is at around pH 7, while...

  10. ELSA: A simplified code for fission product release calculations

    International Nuclear Information System (INIS)

    Manenc, H.; Notley, M.J.

    1996-01-01

    During a light water reactor severe accident, fission products are released from the overheated core as it progressively degrades. A new computer module named ELSA is being developed to calculate fission product release. The authors approach is to model the key phenomena, as opposed to more complete mechanistic approaches. Here they present the main features of the module. Different release mechanisms have been identified and are modeled in ELSA, depending on fission product volatility: diffusion seems to govern the release of the highly volatile species if fuel oxidation is properly accounted for, whereas mass transport governs that of lower volatility fission products and fuel volatilization that of the practically involatile species

  11. Controlled release of diuron from an alginate-bentonite formulation: water release kinetics and soil mobility study.

    Science.gov (United States)

    Fernández-Pérez, M; Villafranca-Sánchez, M; González-Pradas, E; Flores-Céspedes, F

    1999-02-01

    The herbicide diuron was incorporated in alginate-based granules to obtain controlled release (CR) properties. The standard formulation (alginate-herbicide-water) was modified by the addition of different sorbents. The effect on diuron release rate caused by incorporation of natural and acid-treated bentonites in alginate formulation was studied by immersion of the granules in water under static conditions. The release of diuron was diffusion-controlled. The time taken for 50% release of active ingredient to be released into water, T(50), was calculated for the comparison of formulations. The addition of bentonite to the alginate-based formulation produced the higher T(50) values, indicating slower release of the diuron. The mobility of technical and formulated diuron was compared by using soil columns. The use of alginate-based CR formulations containing bentonite produced a less vertical distribution of the active ingredient as compared to the technical product and commercial formulation. Sorption capacities of the various soil constituents for diuron were also determined using batch experiments.

  12. Sum rule limitations of kinetic particle-production models

    International Nuclear Information System (INIS)

    Knoll, J.; CEA Centre d'Etudes Nucleaires de Grenoble, 38; Guet, C.

    1988-04-01

    Photoproduction and absorption sum rules generalized to systems at finite temperature provide a stringent check on the validity of kinetic models for the production of hard photons in intermediate energy nuclear collisions. We inspect such models for the case of nuclear matter at finite temperature employed in a kinetic regime which copes those encountered in energetic nuclear collisions, and find photon production rates which significantly exceed the limits imposed by the sum rule even under favourable concession. This suggests that coherence effects are quite important and the production of photons cannot be considered as an incoherent addition of individual NNγ production processes. The deficiencies of present kinetic models may also apply for the production of probes such as the pion which do not couple perturbatively to the nuclear currents. (orig.)

  13. Kinetics that govern the release of tritium from neutron-irradiated lithium oxide

    International Nuclear Information System (INIS)

    Bertone, P.C.

    1986-01-01

    The Lithium Blanket Module (LBM) program being conducted at the Princeton Plasma Physics Laboratory requires that tritium concentrations as low as 0.1 nCi/g, bred in both LBM lithium oxide pellets and gram-size lithium samples, be measured with an uncertainty not exceeding +/-6%. This thesis reports two satisfactory methods of assaying LBM pellets and one satisfactory method of assaying lithium samples. Results of a fundamental kinetic investigation are also reported. The thermally driven release of tritium from neutron-irradiated lithium oxide pellets is studied between the temperatures of 300 and 400 0 C. The observed release clearly obeys first-order kinetics, and the governing activation energy appears to be 28.4 kcal/mole. Finally, a model is presented that may explain the thermally driven release of tritium from a lithium oxide crystal and assemblies thereof. It predicts that under most circumstances the release is controlled by either the diffusion of a tritiated species through the crystal, or by the desorption of tritiated water from it

  14. Kinetics of immobilisation and release of tryptophan, riboflavin and peptides from whey protein microbeads.

    Science.gov (United States)

    O'Neill, Graham J; Egan, Thelma; Jacquier, Jean Christophe; O'Sullivan, Michael; Dolores O'Riordan, E

    2015-08-01

    This study investigated the kinetics of immobilisation and release of riboflavin, amino acids and peptides from whey microbeads. Blank whey microbeads were placed in solutions of the compounds. As the volume of microbeads added to the solution was increased, the uptake of the compounds increased, to a maximum of 95% for the pentapeptide and 56%, 57% and 45% for the dipeptide, riboflavin and tryptophan respectively, however, the rate of uptake remained constant. The rate of uptake increased with increasing molecule hydrophobicity. The opposite was observed in the release studies, the more hydrophobic compounds had lower release rate constants (kr). When whey microbeads are used as sorbents, they show excellent potential to immobilise small hydrophobic molecules and minimise subsequent diffusion, even in high moisture environments. Copyright © 2015 Elsevier Ltd. All rights reserved.

  15. Tritium release kinetics in lithium orthosilicate ceramic pebbles irradiated with low thermal-neutron fluence

    International Nuclear Information System (INIS)

    Xiao, Chengjian; Gao, Xiaoling; Kobayashi, Makoto; Kawasaki, Kiyotaka; Uchimura, Hiromichi; Toda, Kensuke; Kang, Chunmei; Chen, Xiaojun; Wang, Heyi; Peng, Shuming; Wang, Xiaolin; Oya, Yasuhisa; Okuno, Kenji

    2013-01-01

    Tritium release kinetics in lithium orthosilicate (Li 4 SiO 4 ) ceramic pebbles irradiated with low thermal-neutron fluence was studied by out-of-pile annealing experiments. It was found that the tritium produced in Li 4 SiO 4 pebbles was mainly released as tritiated water vapor (HTO). The apparent desorption activation energy of tritium on the pebble surface was consistent with the diffusion activation energy of tritium in the crystal grains, indicating that tritium release was mainly controlled by diffusion process. The diffusion coefficients of tritium in the crystal grains at temperatures ranging from 450 K to 600 K were obtained by isothermal annealing tests, and the Arrhenius relation was determined to be D = 1 × 10 −7.0 exp (−40.3 × 10 3 /RT) cm 2 s −1

  16. Tritium release kinetics in lithium orthosilicate ceramic pebbles irradiated with low thermal-neutron fluence

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, Chengjian; Gao, Xiaoling [Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Box 919-214, Mian Yang 621900 (China); Kobayashi, Makoto; Kawasaki, Kiyotaka; Uchimura, Hiromichi; Toda, Kensuke [China Academy of Engineering Physics, Box 919-1, Mian Yang 621900 (China); Kang, Chunmei; Chen, Xiaojun; Wang, Heyi; Peng, Shuming [Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Box 919-214, Mian Yang 621900 (China); Wang, Xiaolin, E-mail: xlwang@caep.ac.cn [China Academy of Engineering Physics, Box 919-1, Mian Yang 621900 (China); Oya, Yasuhisa; Okuno, Kenji [Radiochemistry Research Laboratory, Faculty of Science, Shizuoka University, 836 Ohya, Shizuoka 422-8529 (Japan)

    2013-07-15

    Tritium release kinetics in lithium orthosilicate (Li{sub 4}SiO{sub 4}) ceramic pebbles irradiated with low thermal-neutron fluence was studied by out-of-pile annealing experiments. It was found that the tritium produced in Li{sub 4}SiO{sub 4} pebbles was mainly released as tritiated water vapor (HTO). The apparent desorption activation energy of tritium on the pebble surface was consistent with the diffusion activation energy of tritium in the crystal grains, indicating that tritium release was mainly controlled by diffusion process. The diffusion coefficients of tritium in the crystal grains at temperatures ranging from 450 K to 600 K were obtained by isothermal annealing tests, and the Arrhenius relation was determined to be D = 1 × 10{sup −7.0} exp (−40.3 × 10{sup 3}/RT) cm{sup 2} s{sup −1}.

  17. Metallic fission product releases from HTR-spherical fuel elements

    International Nuclear Information System (INIS)

    Helmbold, M.; Amian, W.; Stoever, D.; Hecker, R.

    1978-01-01

    Fission product releases from fuel determines to a large extent the feasibility of a special reactor concept. Basic data describing the diffusion behaviour from coated particle fuel are presented concerning isotopes Cs 137 , Sr 90 and Agsup(110m). Taking into account these data for typical 3000MWth plants release calculations are performed. Sensitive release parameters could be defined and the results show low release figures for all the considered reactor concepts. (author)

  18. Kinetics of aluminum and sulfate release from forest soil by mono- and diprotic aliphatic acids

    Energy Technology Data Exchange (ETDEWEB)

    Evans, A. Jr.; Zelazny, L.W. (Virginia Polytechnic Institute and State Univ., Blacksburg (USA))

    1990-06-01

    A batch equilibration study evaluated the influence of naturally occurring low-molecular-weight mono- and diprotic aliphatic acids on the rate of Al and SO{sub 4}{sup 2{minus}} release in a Cecil soil (Typic Hapludult). The authors adjusted the pH of the organic acids (OAs) and of the soil suspension (3.8% w/w) to pH 4.0 and allowed them to equilibrate thermally before the experiment. After rapid addition of OAs to the soil suspension, they took solution samples at various time intervals and analyzed for Al, SO{sub 4}{sup 2{minus}}, and OA concentration. The initial concentration of OA in suspension was 1 {times} 10{sup {minus}5} mol liter{sup {minus}1}. Both Al and SO{sub 4}{sup 2{minus}} release followed pseudo-first-order kinetics, whereas OA adsorption obeyed simple first-order kinetics. The rate of Al release (k{sub 1}) was more rapid for the diprotic OA treatment (20.4 {times} 10{sup {minus}8} mol s{sup {minus}1}), as was SO{sub 4}{sup 2{minus}} release (1.63 {times} 10{sup {minus}8} mol s{sup {minus}1}), compared to the monoprotic OA treatment. The rate of Al release varied inversely with OA chain length and the distance between -COOH functional groups. The addition of substituent -OH groups between the -COOH groups further reduced K{sub 1}. A similar trend was observed for the rate of SO{sub 4}{sup 2{minus}} release (k{sub 1}) into solution. Monoprotic OAs were more rapidly adsorbed to the particle surfaces than were diprotic OAs. The authors postulate that removal of Al and SO{sub 4}{sup 2{minus}} from solution occurs via selective mineral precipitation.

  19. Effect of bioceramic functional groups on drug binding and release kinetics

    Science.gov (United States)

    Trujillo, Christopher

    Bioceramics have been studied extensively as drug delivery systems (DDS). Those studies have aimed to tailor the drug binding and release kinetics to successfully treat infections and other diseases. This research suggests that the drug binding and release kinetics are predominantly driven by the functional groups available on the surface of a bioceramic. The goal of the present study is to explain the role of silicate and phosphate functional groups in drug binding to and release kinetics from bioceramics. alpha-cristobalite (Cris; SiO2) particles (90-150 microm) were prepared and doped with 0 microg (P-0), 39.1 microg (P-39.1), 78.2 microg (P-78.2), 165.5 microg (P-165.5) or 331 microg (P-331) of P 2O5 per gram Cris, using 85% orthophosphoric (H3PO 4) acid and thermal treatment. The material structure was analyzed using X-ray diffraction (XRD) with Rietveld Refinement and Fourier Transform Infrared (FTIR) spectroscopy with Gaussian fitting. XRD demonstrated an increase from sample P-0 (170.5373 A3) to P-331 (170.6466 A 3) in the unit cell volume as the P2O5 concentration increased in the material confirming phosphate silicate substitution in Cris. Moreover, FTIR showed the characteristic bands of phosphate functional groups of nu4 PO4/O-P-O bending, P-O-P stretching, P-O-P bending, P=O stretching, and P-O-H bending in doped Cris indicating phosphate incorporation in the silicate structure. Furthermore, FTIR showed that the nu4 PO4/O-P-O bending band around 557.6 cm-1 and P=O stretching band around 1343.9 cm-1 increased in area for samples P-39.1 to P-331 from 3.5 to 10.5 and from 10.1 to 22.4, respectively due to phosphate doping. In conjunction with the increase of the nu4 PO4/O-P-O bending band and P=O stretching band, a decrease in area of the O-Si-O bending bands around 488.1 and 629.8 cm-1 was noticed for samples P-39.1 to P-331 from 5 to 2 and from 11.8 to 5.4, respectively. Furthermore, Cris samples (200 mg, n=5 for each sample) were immersed separately in

  20. Release and Decay Kinetics of Copeptin vs AVP in Response to Osmotic Alterations in Healthy Volunteers.

    Science.gov (United States)

    Fenske, Wiebke K; Schnyder, Ingeborg; Koch, Gilbert; Walti, Carla; Pfister, Marc; Kopp, Peter; Fassnacht, Martin; Strauss, Konrad; Christ-Crain, Mirjam

    2018-02-01

    Copeptin is the C-terminal fragment of the arginine vasopressin (AVP) prohormone whose measurement is more robust than that of AVP. Similar release and clearance characteristics have been suggested promoting copeptin as a surrogate marker. To characterize the physiology of osmotically regulated copeptin release and its half-life in direct comparison with plasma AVP. Ninety-one healthy volunteers underwent a standardized three-phase test protocol including (1) osmotic stimulation into the hypertonic range by hypertonic-saline infusion followed by osmotic suppression via (2) oral water load and (3) subsequent glucose infusion. Plasma copeptin, AVP, serum sodium, and osmolality levels were measured in regular intervals. In phase 1, an increase in median osmotic pressure [289 (286; 291) to 311 (309; 314) mOsm/kg H2O] caused similar release kinetics of plasma copeptin [4 (3.1; 6) to 29.3 (18.6; 48.2) pmol/L] and AVP [1 (0.7; 1.6) to 10.3 (6.8; 18.8) pg/mL]. Subsequent osmotic suppression to 298 (295; 301) mOsm/kg at the end of phase 3 revealed markedly different decay kinetics between both peptides-an estimated initial half-life of copeptin being approximately 2 times longer than that of AVP (26 vs 12 minutes). Copeptin is released in equimolar amounts with AVP in response to osmotic stimulation, suggesting its high potential as an AVP surrogate for differentiation of osmotic disorders. Furthermore, we here describe the decay kinetics of copeptin in response to osmotic depression enabling to identify a half-life for copeptin in direct comparison with AVP. Copyright © 2017 Endocrine Society

  1. Fission product release from nuclear fuel I. Physical modelling in the ASTEC code

    International Nuclear Information System (INIS)

    Brillant, G.; Marchetto, C.; Plumecocq, W.

    2013-01-01

    Highlights: • Physical modeling of FP and SM release in ASTEC is presented. • The release is described as solid state diffusion within fuel for high volatile FP. • The release is described as FP vaporisation for semi volatile FP. • The release is described as fuel vaporisation for low volatile FP. • ASTEC validation is presented in the second paper. - Abstract: This article is the first of a series of two articles dedicated to the mechanisms of fission product release from a degraded core as they are modelled in the ASTEC code. The ASTEC code aims at simulating severe accidents in nuclear reactors from the initiating event up to the radiological consequences on the environment. This code is used for several applications such as nuclear plant safety evaluation including probabilistic studies and emergency preparedness. To cope with the requirements of robustness and low calculation time, the code is based on a semi-empirical approach and only the main limiting phenomena that govern the release from intact rods and from debris beds are considered. For solid fuel, fission products are classified into three groups, depending on their degree of volatility. The kinetics of volatile fission products release depend on the rate-limiting process of solid-state diffusion through fuel grains. For semi-volatile fission products, the release from the open fuel porosities is assumed to be governed by vaporisation and mass transfer processes. The key phenomenon for the release of low volatile fission products is supposed to be fuel volatilisation. A similar approach is used for the release of fission products from a rubble bed. An in-depth validation of the code including both analytical and integral experiments is the subject of the second article

  2. Nitrous oxide production kinetics during nitrate reduction in river sediments.

    Science.gov (United States)

    Laverman, Anniet M; Garnier, Josette A; Mounier, Emmanuelle M; Roose-Amsaleg, Céline L

    2010-03-01

    A significant amount of nitrogen entering river basins is denitrified in riparian zones. The aim of this study was to evaluate the influence of nitrate and carbon concentrations on the kinetic parameters of nitrate reduction as well as nitrous oxide emissions in river sediments in a tributary of the Marne (the Seine basin, France). In order to determine these rates, we used flow-through reactors (FTRs) and slurry incubations; flow-through reactors allow determination of rates on intact sediment slices under controlled conditions compared to sediment homogenization in the often used slurry technique. Maximum nitrate reduction rates (R(m)) ranged between 3.0 and 7.1microg Ng(-1)h(-1), and affinity constant (K(m)) ranged from 7.4 to 30.7mg N-NO(3)(-)L(-1). These values were higher in slurry incubations with an R(m) of 37.9microg Ng(-1)h(-1) and a K(m) of 104mg N-NO(3)(-)L(-1). Nitrous oxide production rates did not follow Michaelis-Menten kinetics, and we deduced a rate constant with an average of 0.7 and 5.4ng Ng(-1)h(-1) for FTR and slurry experiments respectively. The addition of carbon (as acetate) showed that carbon was not limiting nitrate reduction rates in these sediments. Similar rates were obtained for FTR and slurries with carbon addition, confirming the hypothesis that homogenization increases rates due to release of and increasing access to carbon in slurries. Nitrous oxide production rates in FTR with carbon additions were low and represented less than 0.01% of the nitrate reduction rates and were even negligible in slurries. Maximum nitrate reduction rates revealed seasonality with high potential rates in fall and winter and low rates in late spring and summer. Under optimal conditions (anoxia, non-limiting nitrate and carbon), nitrous oxide emission rates were low, but significant (0.01% of the nitrate reduction rates). Copyright 2009 Elsevier Ltd. All rights reserved.

  3. Modeling the Release Kinetics of Poorly Water-Soluble Drug Molecules from Liposomal Nanocarriers

    Directory of Open Access Journals (Sweden)

    Stephan Loew

    2011-01-01

    Full Text Available Liposomes are frequently used as pharmaceutical nanocarriers to deliver poorly water-soluble drugs such as temoporfin, cyclosporine A, amphotericin B, and paclitaxel to their target site. Optimal drug delivery depends on understanding the release kinetics of the drug molecules from the host liposomes during the journey to the target site and at the target site. Transfer of drugs in model systems consisting of donor liposomes and acceptor liposomes is known from experimental work to typically exhibit a first-order kinetics with a simple exponential behavior. In some cases, a fast component in the initial transfer is present, in other cases the transfer is sigmoidal. We present and analyze a theoretical model for the transfer that accounts for two physical mechanisms, collisions between liposomes and diffusion of the drug molecules through the aqueous phase. Starting with the detailed distribution of drug molecules among the individual liposomes, we specify the conditions that lead to an apparent first-order kinetic behavior. We also discuss possible implications on the transfer kinetics of (1 high drug loading of donor liposomes, (2 attractive interactions between drug molecules within the liposomes, and (3 slow transfer of drugs between the inner and outer leaflets of the liposomes.

  4. Improved antimicrobial property and controlled drug release kinetics of silver sulfadiazine loaded ordered mesoporous silica

    Directory of Open Access Journals (Sweden)

    Suman Jangra

    2016-09-01

    Full Text Available The present study deals with the loading of silver sulfadiazine into ordered mesoporous silica material by post-impregnation method and its effect on the in vitro release kinetics and antimicrobial property of the drug. The formulated SBA-15 silica material with rope-like morphology and SBA-15-silver sulfadiazine (SBA-AgSD were characterized by UV–visible spectrophotometer, small and wide-angle powder X-ray diffraction (PXRD, field emission scanning electron microscope (FESEM and high resolution transmission electron microscope (HRTEM. Thermo-gravimetric analysis of SBA-AgSD revealed a high loading amount of 52.87%. Nitrogen adsorption–desorption analysis confirmed the drug entrapment into host material by revealing a reduced surface area (214 m2/g and pore diameter (6.7 nm of the SBA-AgSD. The controlled release of silver sulfadiazine drug from the mesoporous silica to simulated gastric, intestinal and body fluids was evaluated. The Korsmeyer–Peppas model fits the drug release data with the non-Fickian diffusion model and zero order kinetics of SBA-AgSD. The antibacterial performance of the SBA-AgSD was evaluated with respect to Staphylococcus aureus, Bacillus subtilis and Pseudomonas aeruginosa. The controlled drug delivery of the SBA-AgSD revealed improved antibacterial activity, thus endorsing its applicability in effective wound dressing.

  5. An analysis of the additional fission product release phenomena

    International Nuclear Information System (INIS)

    Takeda, Tsuneo; Nagai, Hitoshi

    1978-09-01

    The additional fission product release behavior through a defect hole on the cladding of fuel rods has been studied qualitatively with a computer program CODAC-ARFP. The additional fission product release phenomena are described as qualitative evaluation. The additional fission product release behavior in coolant temperature and pressure fluctuations and in reactor start-up and shut-down depends on coolant water flow behavior into and from the free space of fuel rods through a defect hole. Based on the results of evaluations, the experimental results with an inpile water loop OWL-1 are described in detail. The estimation methods of fission product quantity in the free space and fission product release ratio (quantity released into the coolant/quantity in the free space before beginning of release) are necessary for analysis of the fission product release behavior; the estimation method of water flow through a defect hole is also necessary. In development of the above estimation methods, outpile and capsule experiments supporting the additional fission product release experiments are required. (author)

  6. The effect of charge on the release kinetics from polysaccharide–nanoclay composites

    Energy Technology Data Exchange (ETDEWEB)

    Buffa, Stefano Del; Grifoni, Emanuele; Ridi, Francesca, E-mail: francesca.ridi@unifi.it; Baglioni, Piero, E-mail: piero.baglioni@unifi.it [University of Florence, Department of Chemistry “Ugo Schiff” and CSGI (Italy)

    2015-03-15

    The objective of this study was to integrate inorganic halloysite nanotubes (HNT) with chitosan and hyaluronic acid to obtain hybrid nanocomposites with opposing charges and to investigate their potential in the controlled release of drug model probes. Two oppositely charged polysaccharides, chitosan and hyaluronic acid, were selected for their biocompatibility and their importance in biomedical applications. The high surface area and the hollow nanometric-sized lumen of HNT allowed for the efficient loading of rhodamine 110 and carboxyfluorescein, used as models for oppositely charged drugs. In the case of chitosan, the preparation of the nanocomposite was carried out exploiting the electrostatic interaction between the polymer and HNT in water, while with hyaluronic acid, a covalent functionalization strategy was employed to couple the polymer with the clay. Nanocomposites were characterized with thermal, microscopic, and spectroscopic techniques, and the release kinetics of the model compounds was assessed by fluorescence measurements. The release curves were fitted with a model able to account for the desorption process from the external and the internal halloysite surfaces. The results show that both polymeric coatings alter the release of the probes, indicating a key role of both charge and coating composition on the initial and final amount of released dye, as well as on the rate of the desorption process.

  7. Modulation of release kinetics by plasma polymerization of ampicillin-loaded β -TCP ceramics

    International Nuclear Information System (INIS)

    Labay, C; Buxadera-Palomero, J; Avilés, M; Canal, C; Ginebra, M P

    2016-01-01

    Beta-tricalcium phosphate ( β -TCP) bioceramics are employed in bone repair surgery. Their local implantation in bone defects puts them in the limelight as potential materials for local drug delivery. However, obtaining suitable release patterns fitting the required therapeutics is a challenge. Here, plasma polymerization of ampicillin-loaded β -TCP is studied for the design of a novel antibiotic delivery system. Polyethylene glycol-like (PEG-like) coating of β -TCP by low pressure plasma polymerization was performed using diglyme as precursor, and nanometric PEG-like layers were obtained by simple and double plasma polymerization processes. A significant increase in hydrophobicity, and the presence of plasma polymer was visible on the surface by SEM and quantified by XPS. As a main consequence of the plasma polymerisation, the release kinetics were successfully modified, avoiding burst release, and slowing down the initial rate of release leading to a 4.5 h delay in reaching the same antibiotic release percentage, whilst conservation of the activity of the antibiotic was simultaneously maintained. Thus, plasma polymerisation on the surface of bioceramics may be a good strategy to design controlled drug delivery matrices for local bone therapies. (paper)

  8. Steady-state kinetics of substrate binding and iron release in tomato ACC oxidase.

    Science.gov (United States)

    Thrower, J S; Blalock, R; Klinman, J P

    2001-08-14

    1-Aminocyclopropane-1-carboxylate oxidase (ACC oxidase) catalyzes the last step in the biosynthetic pathway of the plant hormone, ethylene. This unusual reaction results in the oxidative ring cleavage of 1-aminocyclopropane carboxylate (ACC) into ethylene, cyanide, and CO2 and requires ferrous ion, ascorbate, and molecular oxygen for catalysis. A new purification procedure and assay method have been developed for tomato ACC oxidase that result in greatly increased enzymatic activity. This method allowed us to determine the rate of iron release from the enzyme and the effect of the activator, CO2, on this rate. Initial velocity studies support an ordered kinetic mechanism where ACC binds first followed by O2; ascorbate can bind after O2 or possibly before ACC. This kinetic mechanism differs from one recently proposed for the ACC oxidase from avocado.

  9. Methane production from cellulosic wastes: kinetic studies

    Energy Technology Data Exchange (ETDEWEB)

    Goma, G; De La Torre, I; Maugheri, F; Yameogo, T

    1979-09-01

    The anaerobic fermentation is studied on lignocellulosic materials and sucrose as substrate. With the lignocellulosic material cellulolysis is rate limiting. The reducing sugar concentration in the fermentation broth is less than 15 mgl/sup -1/. With rumen bacteria, 50% of the initial polyoside are used and 12% of the lignin is solubilized. With sucrose studies on the kinetic behaviour of the mixed population responsible of the acidogenesis step permite to find the optimal temperature (40/sup 0/C) feed substrate concentration (50 gl/sup -1/) residence time (60 hours) and pH (5,5 - 6). The better technology is a plug flow fermentor with cell recycling. Modeling of the behaviour of this reactor was performed. The use of this reactor for the selection of acido resistant bacteria is discussed. For methanogenesis, in continuous culture, the ideal technology seems to be an association of two reactors. In the first step, a plug flow reactor must be used for acidogenesis, and in the second step a well mixed reactor permit the conversion of organic acids in methane.

  10. Kinetics of release of a model disperse dye from supersaturated cellulose acetate matrices.

    Science.gov (United States)

    Papadokostaki, K G; Petropoulos, J H

    1998-08-14

    A study has been made of the kinetics of release into water of a model disperse dye (4-aminoazobenzene) from supersaturated solvent-cast cellulose acetate films at room temperature. Excess dye was introduced into the polymer matrix by: (i) sorption from aqueous solution at 100 degrees C; (ii) sorption from the vapour phase at 110 degrees C; or (iii) prior dissolution in the casting solvent. The effect of the method of introduction of the dye, the degree of supersaturation and the rate of agitation of the bath were investigated. Under conditions of strong agitation, the release kinetics from films dyed by method (i) or (iii) were in general accord with the theoretical model which assumes solute in the film in excess of the saturation limit to be in the form of immobile aggregates at equilibrium with mobile dye; although the value of the diffusion coefficient of the solute in the film was found to be substantially higher than that in the unsaturated film. On the other hand, when dyeing had been effected from the vapour phase, Fickian kinetics was followed and the diffusion coefficient was found to be equal to that observed in unsaturated film. It was concluded that under these conditions, the excess dye in the film tends to remain molecularly dispersed. Under conditions of slow agitation, the square root of t kinetics was not attained in many instances. General and early-time approximate expressions based on the Roseman-Higuchi model proved useful for the interpretation of the results in such cases; while the said model was extended to include the effect of significant variation of the partition coefficient of the solute with concentration.

  11. Yield of reversible colloidal gels during flow start-up: release from kinetic arrest.

    Science.gov (United States)

    Johnson, Lilian C; Landrum, Benjamin J; Zia, Roseanna N

    2018-06-05

    Yield of colloidal gels during start-up of shear flow is characterized by an overshoot in shear stress that accompanies changes in network structure. Prior studies of yield of reversible colloidal gels undergoing strong flow model the overshoot as the point at which network rupture permits fluidization. However, yield under weak flow, which is of interest in many biological and industrial fluids shows no such disintegration. The mechanics of reversible gels are influenced by bond strength and durability, where ongoing rupture and re-formation impart aging that deepens kinetic arrest [Zia et al., J. Rheol., 2014, 58, 1121], suggesting that yield be viewed as release from kinetic arrest. To explore this idea, we study reversible colloidal gels during start-up of shear flow via dynamic simulation, connecting rheological yield to detailed measurements of structure, bond dynamics, and potential energy. We find that pre-yield stress grows temporally with the changing roles of microscopic transport processes: early time behavior is set by Brownian diffusion; later, advective displacements permit relative particle motion that stretches bonds and stores energy. Stress accumulates in stretched, oriented bonds until yield, which is a tipping point to energy release, and is passed with a fully intact network, where the loss of very few bonds enables relaxation of many, easing glassy arrest. This is immediately followed by a reversal to growth in potential energy during bulk plastic deformation and condensation into larger particle domains, supporting the view that yield is an activated release from kinetic arrest. The continued condensation of dense domains and shrinkage of network surfaces, along with a decrease in the potential energy, permit the gel to evolve toward more complete phase separation, supporting our view that yield of weakly sheared gels is a 'non-equilibrium phase transition'. Our findings may be particularly useful for industrial or other coatings, where weak

  12. A model for the release of low-volatility fission products in oxidizing conditions

    International Nuclear Information System (INIS)

    Cox, D.S.; Hunt, C.E.L.; Liu, Z.; Keller, N.A.; Barrand, R.D.; O'Connor, R.F.

    1991-07-01

    A thermodynamic and kinetic model has been developed for calculating low-volatility fission-product releases from UO 2 at high temperatures in oxidizing conditions. Volatilization of the UO 2 matrix is assumed to be the rate controlling process. Oxidation kinetics of the UO 2 are modelled by either interfacial rate control, gas phase oxidant transport control, or solid-state diffusion of oxygen. The vapour pressure of UO 3 in equilibrium with the oxidizing fuel is calculated from thermodynamic data, and volatilization rates are determined using a model for forced convective mass transport. Low-volatility fission-product releases are calculated from the volume of vapourized fuel. Model calculations are conservative compared to experimental data for Zr, La, Ce and Nb fission-product releases from irradiated UO 2 exposed to air at 1973-2350 K. The implications of this conservatism are discussed in terms of possible rate control by processes other than convective mass transport of UO 3 . Coefficients for effective surface area (based on experimental data) and for heterogeneous rate controlling reaction kinetics are introduced to facilitate agreement between calculations and the experimental data.

  13. Relativistic kinetics of baryon production in hot Universe

    International Nuclear Information System (INIS)

    Ignat'ev, Yu.G.

    1985-01-01

    The process of baryon production in the hot Universe is investigated in the framework of the relativistic kinetic theory. The exact solution of kinetic equations for supermassive bosons is obtained, thus giving the possibility to correct the results of previous papers: the known optimum domain of baryon production m sub(X) > α sub(X)msub(PI)√N js complemented by the small-mass boson domain, m sub(X) << α sub(X) m sub(PI)√N; as a result, the cosmological lower-limit restriction on the superheavy bosons masses js removed

  14. Kinetic regularities of the heat release for the interaction of some organic compounds with ammonium nitrate

    Energy Technology Data Exchange (ETDEWEB)

    Rubtsov, Yury I.; Kazakov, Anatoly I.; Lempert, David B.; Manelis, George B. [Institute of Problems of Chemical Physics of Russian Academy of Sciences, Semenov Av. 1, Chernogolovka, Moscow Region, 142432 (Russian Federation)

    2006-12-15

    Ammonium nitrate (AN) is used as an oxidant in a series of systems with a wide spectrum of applications, from explosive compositions up to smokeless stoichiometric self-burning compositions with low combustion temperature. The knowledge of the thermal stability of such compositions is of great importance in using them in practice. In this work the research of kinetics of heat release in the interaction of AN with different organic compounds has been performed using the automatic differential calorimeter. (Abstract Copyright [2006], Wiley Periodicals, Inc.)

  15. Formation kinetics of gemfibrozil chlorination reaction products: analysis and application.

    Science.gov (United States)

    Krkosek, Wendy H; Peldszus, Sigrid; Huck, Peter M; Gagnon, Graham A

    2014-07-01

    Aqueous chlorination kinetics of the lipid regulator gemfibrozil and the formation of reaction products were investigated in deionized water over the pH range 3 to 9, and in two wastewater matrices. Chlorine oxidation of gemfibrozil was found to be highly dependent on pH. No statistically significant degradation of gemfibrozil was observed at pH values greater than 7. Gemfibrozil oxidation between pH 4 and 7 was best represented by first order kinetics. At pH 3, formation of three reaction products was observed. 4'-C1Gem was the only reaction product formed from pH 4-7 and was modeled with zero order kinetics. Chlorine oxidation of gemfibrozil in two wastewater matrices followed second order kinetics. 4'-C1Gem was only formed in wastewater with pH below 7. Deionized water rate kinetic models were applied to two wastewater effluents with gemfibrozil concentrations reported in literature in order to calculate potential mass loading rates of 4'C1Gem to the receiving water.

  16. Intestinal and peritoneal mast cells differ in kinetics of quantal release

    Energy Technology Data Exchange (ETDEWEB)

    Balseiro-Gomez, Santiago, E-mail: sanbalgom@alum.us.es; Ramirez-Ponce, M. Pilar, E-mail: pponce@us.es; Acosta, Jorge, E-mail: jorgealo@us.es; Ales, Eva, E-mail: eales@us.es; Flores, Juan A., E-mail: jaflores@us.es

    2016-01-15

    5-hydroxytriptamine (5-HT, serotonin) storage and release in mast cell (MC) secretory granules (SG) are dependent on serglycin proteoglycans (PG). This notion is based on the studies of MC of the connective tissue subtype that predominantly contain PG of the heparin type, whereas intestinal mucosal MC, which contain predominantly chondroitin sulfate, have been poorly explored. In the present study, we addressed the possibility that PG contents may differently affect the storage and release of preformed mediators in these two MC subclasses and explain in part their different functional properties. Rat peritoneal (PMC) and intestinal mast cells (IMC) were isolated and purified using a percoll gradient, and the efflux of 5-HT from each SG was measured by amperometric detection. IMC exhibited a ∼34% reduction in the release of 5-HT compared with PMC because of a lower number of exocytotic events, rather than a lower secretion per single exocytotic event. Amperometric spikes from IMC exhibited a slower decay phase and increased half-width but a similar ascending phase and foot parameters, indicating that the fusion pore kinetics are comparable in both MC subclasses. We conclude that both PG subtypes are equally efficient systems, directly involved in serotonin accumulation, and play a crucial role in regulating the kinetics of exocytosis from SG, providing specific secretory properties for the two cellular subtypes. - Highlights: • We improved a method for isolating and purifying IMC. • There was a reduction in total serotonin release in IMC with respect to PMC. • This decrease was not due to less secretion per quantum but a lower number of exocytotic events. • There was also a deceleration of exocytosis in IMC with respect to PMC.

  17. Kinetic models for the release of the anticancer drug doxorubicin from biodegradable polylactide/metal oxide-based hybrids

    CSIR Research Space (South Africa)

    Mhlanga, N

    2015-01-01

    Full Text Available For decades, studies on drug-release kinetics have been an important topic in the field of drug delivery because they provide important insights into the mechanism of drug release from carriers. In this work, polylactide (PLA), doxorubicin (DOX...

  18. Obtaining of Sol-Gel Ketorolac-Silica Nanoparticles: Characterization and Drug Release Kinetics

    International Nuclear Information System (INIS)

    Goerne, T.M.L.; Garcia, M.G.L.; Grada, G.R.; Perez, I.O.; Goerne, T.M.L.; Garcia, M.G.L.; Grada, G.R.; Perez, I.O.; Lemus, M.A.A.; Goerne, T.M.L.; Loez, E.G.

    2013-01-01

    Nonsteroidal anti-inflammatory drugs (NSAIDs) are among most commonly prescribed medications worldwide. NSAIDs play an important role due to their pronounced analgesic potency, anti-inflammatory effects, and lesser side effects compared to opioids. However, adverse effects including gastrointestinal and cardiovascular effects seriously complicate their prolonged use. In the present work we prepare SiO 2 -based nanoparticles with ketorolac, for controlled release proposes. The nano materials were prepared by the sol-gel technology at acidic conditions and two different water/alcoxide ratios were used. FTIR spectroscopy was performed in order to characterize the solids and drug-SiO 2 interactions. Thermal analysis and nitrogen adsorption isotherms showed thermal stability of the drug and confirmed the presence of particles with high surface area. Transmission electron micrographs of the samples showed the nano size particles (20 nm) forming aggregates. Drug release profiles were collected by means of UV-Vis spectroscopy and kinetic analysis was developed. Release data were fitted and 1:8 sample showed a sustained release over ten hours; 90% of the drug was delivered at the end of the time.

  19. Characteristics of fission product release from a molten pool

    International Nuclear Information System (INIS)

    Yun, J.I.; Suh, K.Y.; Kang, C.S.

    2001-01-01

    The volatile fission products are released from the debris pool, while the less volatile fission products tend to remain as condensed phases because of their low vapor pressure. The release of noble gases and the volatile fission products is dominated by bubble dynamics. The release of the less volatile fission products from the pool can be analyzed based on mass transport through a liquid with the convection flow. The physico-numerical models were orchestrated from existing submodels in various disciplines of engineering to estimate the released fraction of fission products from a molten pool. It was assumed that the pool has partially filled hemispherical geometry. For the high pool pressure, the diameter of the bubbles at detachment was calculated utilizing the Cole and Shulman correlation with the effect of system pressure. Sensitivity analyses were performed and results of the numerical calculations were compared with analysis results for the TMI-2 accident. (author)

  20. Iron oxide nanoparticle-based magnetic resonance method to monitor release kinetics from polymeric particles with high resolution.

    Science.gov (United States)

    Chan, Minnie; Schopf, Eric; Sankaranarayanan, Jagadis; Almutairi, Adah

    2012-09-18

    A new method to precisely monitor rapid release kinetics from polymeric particles using super paramagnetic iron oxide nanoparticles, specifically by measuring spin-spin relaxation time (T(2)), is reported. Previously, we have published the formulation of logic gate particles from an acid-sensitive poly-β-aminoester ketal-2 polymer. Here, a series of poly-β-aminoester ketal-2 polymers with varying hydrophobicities were synthesized and used to formulate particles. We attempted to measure fluorescence of released Nile red to determine whether the structural adjustments could finely tune the release kinetics in the range of minutes to hours; however, this standard technique did not differentiate each release rate of our series. Thus, a new method based on encapsulation of iron oxide nanoparticles was developed, which enabled us to resolve the release kinetics of our particles. Moreover, the kinetics matched the relative hydrophobicity order determined by octanol-water partition coefficients. To the best of our knowledge, this method provides the highest resolution of release kinetics to date.

  1. Role of various natural, synthetic and semi-synthetic polymers on drug release kinetics of losartan potassium oral controlled release tablets.

    Science.gov (United States)

    Jayasree, J; Sivaneswari, S; Hemalatha, G; Preethi, N; Mounika, B; Murthy, S Vasudeva

    2014-10-01

    The objective of the present work was to formulate and to characterize controlled release matrix tablets of losartan potassium in order to improve bioavailability and to minimize the frequency of administration and increase the patient compliance. Losartan potassium controlled release matrix tablets were prepared by direct compression technique by the use of different natural, synthetic and semisynthetic polymers such as gum copal, gum acacia, hydroxypropyl methyl cellulose K100 (HPMC K100), eudragit RL 100 and carboxy methyl ethyl cellulose (CMEC) individually and also in combination. Studies were carried out to study the influence of type of polymer on drug release rate. All the formulations were subjected to physiochemical characterization such as weight variation, hardness, thickness, friability, drug content, and swelling index. In vitro dissolution studies were carried out simulated gastric fluid (pH 1.2) for first 2 h and followed by simulated intestinal fluid (pH 6.8) up to 24 h, and obtained dissolution data were fitted to in vitro release kinetic equations in order to know the order of kinetics and mechanism of drug release. Results of physiochemical characterization of losartan potassium matrix tablets were within acceptable limits. Formulation containing HPMC K100 and CMEC achieved the desired drug release profile up to 24 h followed zero order kinetics, release pattern dominated by Korsmeyer - Peppas model and mechanism of drug release by nonfickian diffusion. The good correlation obtained from Hixson-Crowell model indicates that changes in surface area of the tablet also influences the drug release. Based on the results, losartan potassium controlled release matrix tablets prepared by employing HPMC K100 and CMEC can attain the desired drug release up to 24 h, which results in maintaining steady state concentration and improving bioavailability.

  2. Purification, product characterization and kinetic properties of soluble tomato lipoxygenase

    NARCIS (Netherlands)

    Vliegenthart, J.F.G.; Suurmeijer, C.N.S.P.; Pérez-Gilabert, M.; Hijden, H.T.W.M. van der; Veldink, G.A.

    1998-01-01

    Soluble lipoxygenase (EC 1.13.11.12) from tomato fruits (Lycopersicon esculentum, var. Trust) was purified to apparent homogeneity as judged by SDS-PAGE, and the products and kinetics of the enzyme were studied in order to clarify the contradictory results that were obtained with a less purified

  3. Kinetic study of sphingomyelin hydrolysis for ceramide production

    DEFF Research Database (Denmark)

    Zhang, Long; Hellgren, Lars; Xu, Xuebing

    2008-01-01

    in cosmetic and pharmaceutical industries such as in hair and skin care products. The enzymatic hydrolysis of sphingomyelin has been proved to be a feasible method to produce ceramide. The kinetic performance of sphingomyelin hydrolysis in the optimal two-phase (water:organic solvent) reaction system...

  4. Influence of corium oxidation on fission product release from molten pool

    Energy Technology Data Exchange (ETDEWEB)

    Bechta, S.V., E-mail: bechta@sbor.spb.s [Alexandrov Scientific-Research Institute of Technology (NITI), Sosnovy Bor (Russian Federation); Krushinov, E.V.; Vitol, S.A.; Khabensky, V.B.; Kotova, S.Yu.; Sulatsky, A.A. [Alexandrov Scientific-Research Institute of Technology (NITI), Sosnovy Bor (Russian Federation); Gusarov, V.V.; Almyashev, V.I. [Grebenschikov Institute of Silicate Chemistry of the Russian Academy of Sciences (ISC RAS), St. Petersburg (Russian Federation); Ducros, G.; Journeau, C. [CEA, DEN, Cadarache, F-13108 St. Paul lez Durance (France); Bottomley, D. [Joint Research Centre Institut fuer Transurane (ITU), Karlsruhe (Germany); Clement, B. [Institut de Radioprotection et Surete Nucleaire (IRSN), St. Paul lez Durance (France); Herranz, L. [CIEMAT, Madrid (Spain); Guentay, S. [PSI, Wuerenlingen (Switzerland); Trambauer, K. [GRS, Muenchen (Germany); Auvinen, A. [VTT, Espoo (Finland); Bezlepkin, V.V. [SPbAEP, St. Petersburg (Russian Federation)

    2010-05-15

    Qualitative and quantitative determination of the release of low-volatile fission products and core materials from molten oxidic corium was investigated in the EVAN project under the auspices of ISTC. The experiments carried out in a cold crucible with induction heating and RASPLAV test facility are described. The results are discussed in terms of reactor application; in particular, pool configuration, melt oxidation kinetics, critical influence of melt surface temperature and oxidation index on the fission product release rate, aerosol particle composition and size distribution. The relevance of measured high release of Sr from the molten pool for the reactor application is highlighted. Comparisons of the experimental data with those from the COLIMA CA-U3 test and the VERCORS tests, as well as with predictions from IVTANTHERMO and GEMINI/NUCLEA codes are made. Recommendations for further investigations are proposed following the major observations and discussions.

  5. Influence of corium oxidation on fission product release from molten pool

    International Nuclear Information System (INIS)

    Bechta, S.V.; Krushinov, E.V.; Vitol, S.A.

    2009-01-01

    Release of low-volatile fission products and core materials from molten oxidic corium was investigated in the EVAN project under the auspices of ISTC. The experiments carried out in cold crucible with induction heating and RASPLAV test facility are described. The results are discussed in terms of reactor application; in particular, pool configuration, melt oxidation kinetics, critical influence of melt surface temperature and oxidation index on the fission product release rate and aerosol particle composition. The relevance of measured high release of Sr from the molten pool for the reactor application is highlighted. Comparisons of the experimental data with those from the COLIMA CA-U3 test and the VERCORS tests, as well as with predictions from IVTANTHERMO and GEMINI/NUCLEA are set. (author)

  6. Kinetics of hydrogen release from dissolutions of ammonia borane in different ionic liquids

    International Nuclear Information System (INIS)

    Valero-Pedraza, María José; Martín-Cortés, Alexandra; Navarrete, Alexander; Bermejo, María Dolores; Martín, Ángel

    2015-01-01

    Ammonia borane is a promising hydrogen storage material that liberates hydrogen by thermolysis at moderate temperatures, but it also presents major limitations for practical applications including a long induction time before the initiation of hydrogen release and a difficult regeneration. Previous works have demonstrated that by dissolution of ammonia borane into several ionic liquids, and particularly in 1-butyl-3-methylimidazolium chloride bmimCl, the induction period at the beginning of the thermolysis is eliminated, but some problems persist, including foaming and the formation of a residue after thermolysis that is insoluble in the ionic liquid. In this work, the release of hydrogen from ammonia borane dissolved in different ionic liquids has been analyzed, measuring the kinetics of hydrogen release, visually following the evolution of the sample during the process using pressure glass tube reactors, and analyzing the residue by spectroscopic techniques. While dissolutions of ammonia borane in most ionic liquids analyzed show similar properties as dissolutions in bmimCl, using ionic liquids with bis(trifluoromethylsulfanyl)imide Tf_2N anion the foaming problem is reduced, and in some cases the residue remains dissolved in the ionic liquid, while with ionic liquids with choline anion higher hydrogen yields are achieved that indicate that the decomposition of ammonia borane proceeds through a different path. - Highlights: • Hydrogen release from ammonia borane dissolved in 13 ionic liquids has been studied. • Induction time is shortened and hydrogen release rate is accelerated in all cases. • The best results are obtained using ionic liquids with Tf_2N anion. • Ch cation ionic liquids enable higher H_2 yield, but cyclotriborazane is produced.

  7. Empirical and mechanistic evaluation of NH4(+) release kinetic in calcareous soils.

    Science.gov (United States)

    Ranjbar, F; Jalali, M

    2014-05-01

    Release, fixation, and distribution of ammonium (NH4(+)) as a source of nitrogen can play an important role in soil fertility and plant nutrition. In this study, ten surface soils, after addition of 1,000 mg NH4(+) kg(-1,) were incubated for 1 week at the field capacity moisture and 25 ± 2 °C temperature, and then NH4(+) release kinetic was investigated by sequential extractions with 10 mM CaCl2. Furthermore, NH4(+) distribution among three fractions, including water-soluble, exchangeable, and non-exchangeable, was determined in all soil samples. NH4(+) release was initially rapid followed by a slower reaction, and this was described well with the Elovich equation as an empirical model. The cumulative NH4(+) concentration released in spiked soil samples had a positive significant correlation with sand content and negative ones with pH, exchangeable Ca(2+)m and K(+), cation exchange capacity (CEC), equivalent calcium carbonate (ECC), and clay content. The cation exchange model in the PHREEQC program was successful in mechanistic simulation of the release trend of native and added NH4(+) in all control and spiked soil samples. The results of fractionation experiments showed that the non-exchangeable fraction in control and spiked soil samples was greater than that in water-soluble and exchangeable fractions. Soil properties, such as pH, exchangeable Ca(2+) and K(+), CEC, ECC, and contents of sand and clay, had significant influences on the distribution of NH4(+) among three measured fractions. This study indicated that both native and recently fixed NH4(+), added to soil through the application of fertilizers, were readily available for plant roots during 1 week after exposure.

  8. Kinetic Analysis of the Uptake and Release of Fluorescein by Metal-Organic Framework Nanoparticles

    Directory of Open Access Journals (Sweden)

    Tobias Preiß

    2017-02-01

    Full Text Available Metal-organic framework nanoparticles (MOF NPs are promising guest-host materials with applications in separation, storage, catalysis, and drug delivery. However, on- and off-loading of guest molecules by porous MOF nanostructures are still poorly understood. Here we study uptake and release of fluorescein by two representative MOF NPs, MIL-100(Fe and MIL-101(Cr. Suspensions of these MOF NPs exhibit well-defined size distributions and crystallinity, as verified by electron microscopy, dynamic light scattering, and X-ray diffraction. Using absorbance spectroscopy the equilibrium dissociation constants and maximum numbers of adsorbed fluorescein molecules per NP were determined. Time-resolved fluorescence studies reveal that rates of release and loading are pH dependent. The kinetics observed are compared to theoretical estimates that account for bulk diffusion into NPs, and retarded internal diffusion and adsorption rates. Our study shows that, rather than being simple volumetric carriers, MOF-NPs are dominated by internal surface properties. The findings will help to optimize payload levels and develop release strategies that exploit varying pH for drug delivery.

  9. Comparison of kinetic model for biogas production from corn cob

    Science.gov (United States)

    Shitophyta, L. M.; Maryudi

    2018-04-01

    Energy demand increases every day, while the energy source especially fossil energy depletes increasingly. One of the solutions to overcome the energy depletion is to provide renewable energies such as biogas. Biogas can be generated by corn cob and food waste. In this study, biogas production was carried out by solid-state anaerobic digestion. The steps of biogas production were the preparation of feedstock, the solid-state anaerobic digestion, and the measurement of biogas volume. This study was conducted on TS content of 20%, 22%, and 24%. The aim of this research was to compare kinetic models of biogas production from corn cob and food waste as a co-digestion using the linear, exponential equation, and first-kinetic models. The result showed that the exponential equation had a better correlation than the linear equation on the ascending graph of biogas production. On the contrary, the linear equation had a better correlation than the exponential equation on the descending graph of biogas production. The correlation values on the first-kinetic model had the smallest value compared to the linear and exponential models.

  10. Fission product release from fuel of water-cooled reactors

    International Nuclear Information System (INIS)

    Strupczewski, A.; Marks, P.; Klisinska, M.

    1997-01-01

    The report contains a review of theoretical models and experimental works of gaseous and volatile fission products from uranium dioxide fuel. The experimental results of activity release at low burnup and the model of fission gas behaviour at initial stage of fuel operational cycle are presented. Empirical models as well as measured results of transient fission products release rate in the temperature up to UO 2 melting point, with consideration of their chemical reactions with fuel and cladding, are collected. The theoretical and experimental data were used for calculations of gaseous and volatile fission products release, especially iodine and caesium, to the gas volume of WWER-1000 and WWER-440 type fuel rods at low and high burnup and their further release from defected rods at the assumed loss-of-coolant accident. (author)

  11. Swelling kinetics of spray-dried chitosan acetate assessed by magnetic resonance imaging and their relation to drug release kinetics of chitosan matrix tablets.

    Science.gov (United States)

    Huanbutta, Kampanart; Sriamornsak, Pornsak; Limmatvapirat, Sontaya; Luangtana-anan, Manee; Yoshihashi, Yasuo; Yonemochi, Etsuo; Terada, Katsuhide; Nunthanid, Jurairat

    2011-02-01

    Magnetic resonance imaging (MRI) was used to assess in situ swelling behaviors of spray-dried chitosan acetate (CSA) in 0.1N HCl, pH 6.8 and pH 5.0 Tris-HCl buffers. The in vitro drug releases from CSA matrix tablets containing the model drugs, diclofenac sodium and theophylline were investigated in all media using USP-4 apparatus. The effect of chitosan molecular weight, especially in pH 6.8 Tris-HCl, was also studied. In 0.1N HCl, the drug release from the matrix tablets was the lowest in relation to the highest swelling of CSA. The swelling kinetics in Tris-HCl buffers are Fickian diffusion according to their best fit to Higuchi's model as well as the drug release kinetics in all the media. The high swelling rate (k(s)(')) was found to delay the drug release rate (k'). The linear relationship between the swelling and fractions of drug release in Tris-HCl buffers was observed, indicating an important role of the swelling on controlling the drug release mechanism. Additionally, CSA of 200 and 800 kDa chitosan did not swell in pH 6.8 Tris-HCl but disintegrated into fractions, and the drug release from the matrix tablets was the highest. Copyright © 2010 Elsevier B.V. All rights reserved.

  12. Time extrapolation of radiolytic degradation product kinetics: the case of polyurethane

    International Nuclear Information System (INIS)

    Dannoux, A.

    2007-02-01

    The prediction of the environmental impact of organic materials in nuclear waste geological storage needs knowledge of radiolytic degradation mechanisms and kinetics in aerobic and anaerobic conditions. In this framework, the effect of high doses (> MGy) and the variation of dose rate have to be considered. The material studied is a polyurethane composed of polyether soft segment and aromatic hard segments. Mechanisms were built on the analysis of material submitted to irradiations of simulation (high energy electrons and gamma radiation) by FTIR spectroscopy and gaseous and liquid degradation products by gas mass spectrometry and size exclusion chromatography. The electron paramagnetic resonance study of radical process and the determination of oxygen consumption and gas formation radiolytic yields allowed us to acquire kinetic data and to estimate dose rate and high doses effects. The polyurethane radio-oxidation mainly concerns soft segments and induced cross-linkings and production by scissions of oxidised compounds (esters, alcohols, carboxylic acids). The kinetic of radical termination is rapid and the dose rate effect is limited. After 10 MGy, branching and scission reactions are in equilibrium and low molecular weight products accumulate. At last, the degradation products release in water is influenced by the oxidation rate and the temperature. After 10 MGy, the soluble fraction is stabilised at 25%. The water soluble products identified by electro-spray ionisation mass spectrometry (alcohols, aldehydes, carboxylic acids) potentially formed complexes with radionuclides. (author)

  13. On the sequence of core-melt accidents: Fission product release, source terms and Chernobyl release

    Energy Technology Data Exchange (ETDEWEB)

    Albrecht, H

    1986-01-01

    There is a sketch of our ideas on the course of a core melt-out accident in a PWR. There is then a survey of the most important results on fission product release, which were obtained by experiments on the SASCHA melt-out plant. The 3rd part considers questions which are important for determining source terms for the environment and the last part contains some considerations on radioactivity release from the Chernobyl reactor.

  14. Characterization of drug-release kinetics in trabecular bone from titania nanotube implants

    Directory of Open Access Journals (Sweden)

    Aw MS

    2012-09-01

    Full Text Available Moom Sinn Aw,1 Kamarul A Khalid,2,3 Karan Gulati,1 Gerald J Atkins,2 Peter Pivonka,4 David M Findlay,2 Dusan Losic11School of Chemical Engineering, 2Discipline of Orthopaedics and Trauma, The University of Adelaide, Adelaide, SA, Australia; 3Department of Orthopaedics, Traumatology and Rehabilitation, Faculty of Medicine, International Islamic University Malaysia, Kuantan, Pahang, Malaysia; 4Engineering Computational Biology Group, School of Computer Science and Software Engineering, The University of Western Australia, Perth, WA, AustraliaPurpose: The aim of this study was to investigate the application of the three-dimensional bone bioreactor for studying drug-release kinetics and distribution of drugs in the ex vivo cancellous bone environment, and to demonstrate the application of nanoengineered titanium (Ti wires generated with titania nanotube (TNT arrays as drug-releasing implants for local drug deliveryMethods: Nanoengineered Ti wires covered with a layer of TNT arrays implanted in bone were used as a drug-releasing implant. Viable bovine trabecular bone was used as the ex vivo bone substrate embedded with the implants and placed in the bone reactor. A hydrophilic fluorescent dye (rhodamine B was used as the model drug, loaded inside the TNT–Ti implants, to monitor drug release and transport in trabecular bone. The distribution of released model drug in the bone was monitored throughout the bone structure, and concentration profiles at different vertical (0–5 mm and horizontal (0–10 mm distances from the implant surface were obtained at a range of release times from 1 hour to 5 days.Results: Scanning electron microscopy confirmed that well-ordered, vertically aligned nanotube arrays were formed on the surface of prepared TNT–Ti wires. Thermogravimetric analysis proved loading of the model drug and fluorescence spectroscopy was used to show drug-release characteristics in-vitro. The drug release from implants inserted into bone ex

  15. Anisotropic kinetic energy release and gyroscopic behavior of CO2 super rotors from an optical centrifuge

    Science.gov (United States)

    Murray, Matthew J.; Ogden, Hannah M.; Mullin, Amy S.

    2017-10-01

    An optical centrifuge is used to generate an ensemble of CO2 super rotors with oriented angular momentum. The collision dynamics and energy transfer behavior of the super rotor molecules are investigated using high-resolution transient IR absorption spectroscopy. New multipass IR detection provides improved sensitivity to perform polarization-dependent transient studies for rotational states with 76 ≤ J ≤ 100. Polarization-dependent measurements show that the collision-induced kinetic energy release is spatially anisotropic and results from both near-resonant energy transfer between super rotor molecules and non-resonant energy transfer between super rotors and thermal molecules. J-dependent studies show that the extent and duration of the orientational anisotropy increase with rotational angular momentum. The super rotors exhibit behavior akin to molecular gyroscopes, wherein molecules with larger amounts of angular momentum are less likely to change their angular momentum orientation through collisions.

  16. Kinetics of Methane Production from Swine Manure and Buffalo Manure.

    Science.gov (United States)

    Sun, Chen; Cao, Weixing; Liu, Ronghou

    2015-10-01

    The degradation kinetics of swine and buffalo manure for methane production was investigated. Six kinetic models were employed to describe the corresponding experimental data. These models were evaluated by two statistical measurements, which were root mean square prediction error (RMSPE) and Akaike's information criterion (AIC). The results showed that the logistic and Fitzhugh models could predict the experimental data very well for the digestion of swine and buffalo manure, respectively. The predicted methane yield potential for swine and buffalo manure was 487.9 and 340.4 mL CH4/g volatile solid (VS), respectively, which was close to experimental values, when the digestion temperature was 36 ± 1 °C in the biochemical methane potential assays. Besides, the rate constant revealed that swine manure had a much faster methane production rate than buffalo manure.

  17. Modeling of fission product release in integral codes

    International Nuclear Information System (INIS)

    Obaidurrahman, K.; Raman, Rupak K.; Gaikwad, Avinash J.

    2014-01-01

    The Great Tohoku earthquake and tsunami that stroke the Fukushima-Daiichi nuclear power station in March 11, 2011 has intensified the needs of detailed nuclear safety research and with this objective all streams associated with severe accident phenomenology are being revisited thoroughly. The present paper would cover an overview of state of art FP release models being used, the important phenomenon considered in semi-mechanistic models and knowledge gaps in present FP release modeling. Capability of FP release module, ELSA of ASTEC integral code in appropriate prediction of FP release under several diversified core degraded conditions will also be demonstrated. Use of semi-mechanistic fission product release models at AERB in source-term estimation shall be briefed. (author)

  18. Release of fission products during and after oxidation of trace-irradiated uranium dioxide at 300-900 deg. C

    Energy Technology Data Exchange (ETDEWEB)

    Wood, P; Bannister, G H [Central Electricity Generating Board, Berkeley Nuclear Laboratories (United Kingdom)

    1985-07-01

    Should defected UO{sub 2} fuel pins come into contact with air then oxidation of the fuel may occur, the rate and consequences of which are dependent upon temperature and oxygen partial pressure. At CEGB-BNL an experimental programme is underway investigating the kinetics, and extent, of release of fission products during and after oxidation of trace-irradiated UO{sub 2} to U{sub 3}O{sub 8}, and reduction of U{sub 3}O{sub 8} to UO{sub 2}. This paper presents preliminary results and analysis of experiments performed at 300-900 deg. C. Dense sintered UO{sub 2} has been oxidised at 300-500 deg. C using a thermo balance with simultaneous counting of released {sup 85}Kr. The kinetics of the {sup 85}Kr release are shown to correlate with the kinetics of oxidation, and the extent of release has been determined as 3-8% of that in the UO{sub 2} converted to U{sub 3}O{sub 8}. The release of {sup 106}Ru and {sup 137}Cs during this oxidation has been estimated by {gamma}-counting of the fuel sample, before and after oxidation, and of glassware in the vicinity of the sample. This indicates slight release of ruthenium and caesium. Greater fission product release is caused by oxidation at higher temperatures or by heating of the oxidation product. U{sub 3}O{sub 8} produced at 400 deg. C has been heated at 800 and 900 deg. C in air for 20 hours. This results in near total release of {sup 85}Kr and {sup 106}Ru, but still only slight release of {sup 137}Cs. The kinetics of the {sup 85}Kr release have been analysed and found to follow the Booth diffusion equation at 900 deg. C, but not at 800 deg. C. The fuel burn-up level may also have an effect. Some results of fission product release during reduction of the oxidation product U{sub 3}O{sub 8} are presented, and the influence of chemical effects upon the release of individual fission products is discussed. The future programme is outlined. (author)

  19. Recoil release of fission products from nuclear fuel

    International Nuclear Information System (INIS)

    Wise, C.

    1985-01-01

    An analytical approximation is developed for calculating recoil release from nuclear fuel into gas filled interspaces. This expression is evaluated for a number of interspace geometries and shown to be generally accurate to within about 10% by comparison with numerical calculations. The results are applied to situations of physical interest and it is demonstrated that recoil can be important when modelling fission product release from low temperature CAGR pin failures. Furthermore, recoil can contribute significantly in experiments on low temperature fission product release, particularly where oxidation enhancement of this release is measured by exposing the fuel to CO 2 . The calculations presented here are one way of allowing for this, other methods are suggested. (orig.)

  20. Transient fission product release during reactor shutdown and startup

    International Nuclear Information System (INIS)

    Hunt, C.E.L.; Lewis, B.J.

    1995-01-01

    Sweep gas experiments performed at CRL from 1979 to 1985 have been analysed to determine the fraction of the fission product gas inventory that is released on reactor shutdown and startup. Empirical equations were derived and applied to calculate the xenon release from companion fuel elements and from a well documented experimental fuel bundle irradiated in the NRU reactor. The measured gas release could be matched to within about a factor of two for an experimental irradiation with a burnup of 217 MWh/kgU. (author)

  1. Release of fission and activation products during LWR core meltdown

    International Nuclear Information System (INIS)

    Albrecht, H.; Matschoss, V.; Wild, H.

    1978-01-01

    Experiments are described by which activity release fractions and aerosol characteristics were investigated for various core melting conditions. Samples of corium and fissium were heated by induction to temperatures of 2800 0 C under air, argon and steam. Release values are presented for Cr, Mn, Fe, Co, Se, Zr, Mo, Cd, Sn, Sb, Te, J, Cs and U. The deposition behaviour of the released products was found to depend strongly on the volatility and on the gas flow rate. Preliminary results of additional measurements indicate that the size distribution of the aerosol particles is trimodal. (author)

  2. Multiphasic analysis of gas production kinetics for in vitro fermentation of ruminant feeds.

    NARCIS (Netherlands)

    Groot, J.C.J.; Cone, J.W.; Williams, B.A.; Debersaques, F.M.A.; Lantinga, E.A.

    1996-01-01

    Recently developed time-related gas production techniques to quantify the kinetics of ruminant feed fermentation have a high resolution. Consequently, fermentation processes with clearly contrasting gas production kinetics can be identified. Parameterization of the separate processes is possible

  3. The effect of excipients on the release kinetics of diclofenac sodium and papaverine hydrochloride from composed tablets.

    Science.gov (United States)

    Kasperek, Regina; Trebacz, Hanna; Zimmer, Łukasz; Poleszak, Ewa

    2014-01-01

    For increased analgesic effect, new composed tablets containing diclofenac sodium (DIC) with an addition of papaverine hydrochloride (PAP) were prepared to investigate the mechanism of release of the active substances from tablets with different excipients in eight different formulations. To detect the possible interactions between active substances and excipients differential scanning calorimetry (DSC) was used. A shift of the melting point and enthalpy values of the physical mixtures of tablets components suggested a kind of interaction between components in certain formulations, however, the tabletting process was not disturbed in any of them. Kinetics of drug release from formulations was estimated by zero order, first order and Higuchi and Korsmeyer-Peppas models using results of dissolution of DIC and PAP from tablets. The study revealed that the mechanism of release of active substances was dependent on the excipients contained in tablets and the best fitted kinetics models were obtained for formulations with potentially prolonged release of DIC and PAP.

  4. [Batch release of immunoglobulin and monoclonal antibody products].

    Science.gov (United States)

    Gross, S

    2014-10-01

    The Paul-Ehrlich Institute (PEI) is an independent institution of the Federal Republic of Germany responsible for performing official experimental batch testing of sera. The institute decides about the release of each batch and performs experimental research in the field. The experimental quality control ensures the potency of the product and also the absence of harmful impurities. For release of an immunoglobulin batch the marketing authorization holder has to submit the documentation of the manufacture and the results of quality control measures together with samples of the batch to the PEI. Experimental testing is performed according to the approved specifications regarding the efficacy and safety. Since implementation of the 15th German drug law amendment, the source of antibody is not defined anymore. According to § 32 German drug law, all batches of sera need to be released by an official control laboratory. Sera are medicinal products, which contain antibodies, antibody fragments or fusion proteins with a functional antibody portion. Therefore, all batches of monoclonal antibodies and derivatives must also be released by the PEI and the marketing authorization holder has to submit a batch release application. Under certain circumstances a waiver for certain products can be issued with regard to batch release. The conditions for such a waiver apply to the majority of monoclonal antibodies.

  5. ACRR fission product release tests: ST-1 and ST-2

    International Nuclear Information System (INIS)

    Allen, M.D.; Stockman, H.W.; Reil, K.O.; Grimley, A.J.; Camp, W.J.

    1988-01-01

    Two experiments (ST-1 and ST-2) have been performed in the Annular Core Research Reactor (ACRR) at Sandia National Laboratories (SNLA) to obtain time-resolved data on the release of fission products from irradiated fuels under light water reactor (LWR) severe accident conditions. Both experiments were conducted in a highly reducing environment at maximum fuel temperatures of greater than 2400 K. These experiments were designed specifically to investigate the effect of increased total pressure on fission product release; ST-1 was performed at approximately 0.16 MPa and ST-2 was run at 1.9 MPa, whereas other parameters were matched as closely as possible. Release rate data were measured for Cs, I, Ba, Sr, Eu, Te, and U. The release rates were higher than predicted by existing codes for Ba, Sr, Eu, and U. Te release was very low, but Te did not appear to be sequestered by the zircaloy cladding; it was evenly distributed in the fuel. In addition, in posttest analysis a unique fuel morphology (fuel swelling) was observed which may have enhanced fission product release, especially in the high pressure test (ST-2). These data are compared with analytical results from the CORSOR correlation and the VICTORIA computer model

  6. Fission-product releases from a PHWR terminal debris bed

    Energy Technology Data Exchange (ETDEWEB)

    Brown, M.J.; Bailey, D.G., E-mail: morgan.brown@cnl.ca [Canadian Nuclear Laboratories, Chalk River, Ontario (Canada)

    2016-06-15

    During an unmitigated severe accident in a pressurized heavy water reactor (PHWR) with horizontal fuel channels, the core may disassemble and relocate to the bottom of the calandria vessel. The resulting heterogeneous in-vessel terminal debris bed (TDB) would likely be quenched by any remaining moderator, and some of the decay heat would be conducted through the calandria vessel shell to the surrounding reactor vault or shield tank water. As the moderator boiled off, the solid debris bed would transform into a more homogeneous molten corium pool located between top and bottom crusts. Until recently, the severe accident code MAAP-CANDU assumed that unreleased volatile and semi-volatile fission products remained in the TDB until after calandria vessel failure, due to low diffusivity through the top crust and the lack of gases or steam to flush released fission products from the debris. However, national and international experimental results indicate this assumption is unlikely; instead, high- and medium-volatility fission products would be released from a molten debris pool, and their volatility and transport should be taken into account in TDB modelling. The resulting change in the distribution of fission products within the reactor and containment, and the associated decay heat, can have significant effects upon the progression of the accident and fission-product releases to the environment. This article describes a postulated PHWR severe accident progression to generate a TDB and the effects of fission-product releases from the terminal debris, using the simple release model in the MAAP-CANDU severe accident code. It also provides insights from various experimental programs related to fission-product releases from core debris, and their applicability to the MAAP-CANDU TDB model. (author)

  7. IGF-1 release kinetics from chitosan microparticles fabricated using environmentally benign conditions

    Energy Technology Data Exchange (ETDEWEB)

    Mantripragada, Venkata P. [Biomedical Engineering Program, The University of Toledo, Toledo, OH 43614-5807 (United States); Jayasuriya, Ambalangodage C., E-mail: a.jayasuriya@utoledo.edu [Biomedical Engineering Program, The University of Toledo, Toledo, OH 43614-5807 (United States); Department of Orthopaedic Surgery, The University of Toledo, Toledo, OH 43614-5807 (United States)

    2014-09-01

    The main objective of this study is to maximize growth factor encapsulation efficiency into microparticles. The novelty of this study is to maximize the encapsulated growth factors into microparticles by minimizing the use of organic solvents and using relatively low temperatures. The microparticles were fabricated using chitosan biopolymer as a base polymer and cross-linked with tripolyphosphate (TPP). Insulin like-growth factor-1 (IGF-1) was encapsulated into microparticles to study release kinetics and bioactivity. In order to authenticate the harms of using organic solvents like hexane and acetone during microparticle preparation, IGF-1 encapsulated microparticles prepared by the emulsification and coacervation methods were compared. The microparticles fabricated by emulsification method have shown a significant decrease (p < 0.05) in IGF-1 encapsulation efficiency, and cumulative release during the two-week period. The biocompatibility of chitosan microparticles and the bioactivity of the released IGF-1 were determined in vitro by live/dead viability assay. The mineralization data observed with von Kossa assay, was supported by mRNA expression levels of osterix and runx2, which are transcription factors necessary for osteoblasts differentiation. Real time RT-PCR data showed an increased expression of runx2 and a decreased expression of osterix over time, indicating differentiating osteoblasts. Chitosan microparticles prepared in optimum environmental conditions are a promising controlled delivery system for cells to attach, proliferate, differentiate and mineralize, thereby acting as a suitable bone repairing material. - Highlights: • Coacervation chitosan microparticles were biocompatible and biodegradable. • IGF-1 encapsulation efficiency increased with coacervation chitosan microparticles. • Coacervation chitosan microparticles support osteoblast attachment and differentiation. • Coacervation chitosan microparticles support osteoblast mineralization.

  8. IGF-1 release kinetics from chitosan microparticles fabricated using environmentally benign conditions

    International Nuclear Information System (INIS)

    Mantripragada, Venkata P.; Jayasuriya, Ambalangodage C.

    2014-01-01

    The main objective of this study is to maximize growth factor encapsulation efficiency into microparticles. The novelty of this study is to maximize the encapsulated growth factors into microparticles by minimizing the use of organic solvents and using relatively low temperatures. The microparticles were fabricated using chitosan biopolymer as a base polymer and cross-linked with tripolyphosphate (TPP). Insulin like-growth factor-1 (IGF-1) was encapsulated into microparticles to study release kinetics and bioactivity. In order to authenticate the harms of using organic solvents like hexane and acetone during microparticle preparation, IGF-1 encapsulated microparticles prepared by the emulsification and coacervation methods were compared. The microparticles fabricated by emulsification method have shown a significant decrease (p < 0.05) in IGF-1 encapsulation efficiency, and cumulative release during the two-week period. The biocompatibility of chitosan microparticles and the bioactivity of the released IGF-1 were determined in vitro by live/dead viability assay. The mineralization data observed with von Kossa assay, was supported by mRNA expression levels of osterix and runx2, which are transcription factors necessary for osteoblasts differentiation. Real time RT-PCR data showed an increased expression of runx2 and a decreased expression of osterix over time, indicating differentiating osteoblasts. Chitosan microparticles prepared in optimum environmental conditions are a promising controlled delivery system for cells to attach, proliferate, differentiate and mineralize, thereby acting as a suitable bone repairing material. - Highlights: • Coacervation chitosan microparticles were biocompatible and biodegradable. • IGF-1 encapsulation efficiency increased with coacervation chitosan microparticles. • Coacervation chitosan microparticles support osteoblast attachment and differentiation. • Coacervation chitosan microparticles support osteoblast mineralization

  9. Novel Caffeic Acid Nanocarrier: Production, Characterization, and Release Modeling

    Directory of Open Access Journals (Sweden)

    Milad Fathi

    2013-01-01

    Full Text Available This paper deals with the development of novel nanocarriers using layer by layer carbohydrate coating of caffeic acid loaded solid lipid nanoparticles (SLNs to improve stability and colon delivery of the poorly water-soluble caffeic acid. Three biopolymers (chitosan, alginate, and pectin in different concentrations (0.1, 0.25, and 0.5% were electrostatically coated over the SLN surface. The size and zeta potential of produced nanocarriers were measured using photon correlation spectroscopy. Mathematical models (i.e., zero-order, first-order, Higuchi, Ritger-Peppas, reciprocal powered time, Weibull, and quadratic models were used to describe the release and kinetic modeling in gastrointestinal solution (GIS. Also, antioxidant activity of caffeic acid during the release in GIS was investigated using DPPH and reducing activity methods. The prepared treatments coated by alginate-chitosan as well as pectin-chitosan coated SLN at the concentration of 0.1% showed nanosized bead; the latter efficiently retarded the release of caffeic acid in gastric media up to 2.5 times higher than that of SLN. Zeta potential values of coated samples were found to significantly increase in comparison to SLN indicating the higher stability of produced nanocarriers. Antioxidant activity of caffeic acid after gastric release did not result in the same trend as observed for caffeic acid release from different treatments; however, in line with less caffeic acid release in the intestine solution by the effect of coating, lower antioxidant activity was determined at the end stage of the experiment.

  10. Fission product released experiment of coated fuel particles

    Energy Technology Data Exchange (ETDEWEB)

    Shijiang, Xu; Bing, Yang; Chunhe, Tang; Junguo, Zhu; Jintao, Huang; Binzhong, Zhang [Inst. of Nucl. Energy Technology, Tsinghua Univ., Beijing (China); Jinghan, Luo [Inst. of Atomic Energy, Beijing (China)

    1992-01-15

    Four samples of coated fuel particles were irradiated in the Heavy-Water Research Reactor of the Institute of Atomic Energy. Each of them was divided into two groups and irradiated to the burn up of 0.394% fima and 0.788% fima in two static capsules, respectively. After irradiation and cooling, post irradiation annealing experiment was carried out, the release ratios of the fission product {sup 133}Xe and {sup 131}I were measured, they are in the order of 10{sup -6}{approx}10{sup -7}. The fission product release ratio of naked kernel was also measured under the same conditions as for the coated fuel particles, the ratio of the fission product release of the coated fuel particles and of the naked kernel was in the order of 10{sup -5}{approx}10{sup -4}.

  11. Atmosphere dependence of fission products release: The Vercors 4 and 5 experiments

    Energy Technology Data Exchange (ETDEWEB)

    Andre, B.; Ducros, G.; Tourasse, M.; Ferroud-Plattet, M.P. [CEA Centre d`Etudes de Grenoble, 38 (France). Dept. de Thermohydraulique et de Physique; Boulaud, D. [CEA Centre d`Etudes de Fontenay-aux-Roses, 92 (France). Inst. de Protection et de Surete Nucleaire

    1996-12-31

    Because of the severe consequences, in terms of radiological and biological effects, of a nuclear accident, the international reactor safety authorities initiated, 25 years ago, numerous experimental programs in order to improve the understanding and the prediction of these situations. In France, the Nuclear Protection and Safety Institute (IPSN) in collaboration with Electricite de France (EDF) co-fund the Heva-Vercors program, since 1983. The experiments are conducted in a shielded hot cell of the LAMA facility at Grenoble. The test specimen is a fuel rod section taken from a power reactor operated by EDF and includes three irradiated pellets in their original cladding. The fuel sample is re-irradiated at low power in the Siloe experimental reactor for seven days in order to recreate the short-lived fission products without inducing any in-pile release. Since the experimental sequence is performed less than 40 hours after the end of the reirradiation, direct measurement of radioactive fission products release is possible using gamma spectrometry. The measurements performed during the tests are essentially aimed at characterising the release kinetics and the total release of fission products and structural materials as a function of fuel temperature and oxidising/reducing conditions of the environment. The four last tests (Vercors 3 to Vercors 6), performed at 2600 K, allowed to measure the kinetic of high and low volatile species release, as well as the total released fraction of non volatile species and the transuranic elements. This paper is devoted to the comparison of the Vercors 4 and Vercors 5 tests. The first one has been conducted up to 2600 K under reducing conditions (hydrogen fluid), after an oxidising period at 1670 K. The second one was performed in a pure steam atmosphere after several plateaus at intermediate temperatures in oxidising conditions. The total release of volatile (Sb, Te, I, Cs) is not significantly modified and a higher release of Mo

  12. Modulation of drug release kinetics of shellac-based matrix tablets by in-situ polymerization through annealing process.

    Science.gov (United States)

    Limmatvapirat, Sontaya; Limmatvapirat, Chutima; Puttipipatkhachorn, Satit; Nunthanid, Jurairat; Luangtana-anan, Manee; Sriamornsak, Pornsak

    2008-08-01

    A new oral-controlled release matrix tablet based on shellac polymer was designed and developed, using metronidazole (MZ) as a model drug. The shellac-based matrix tablets were prepared by wet granulation using different amounts of shellac and lactose. The effect of annealing temperature and pH of medium on drug release from matrix tablets was investigated. The increased amount of shellac and increased annealing temperature significantly affected the physical properties (i.e., tablet hardness and tablet disintegration) and MZ release from the matrix tablets. The in-situ polymerization played a major role on the changes in shellac properties during annealing process. Though the shellac did not dissolve in acid medium, the MZ release in 0.1N HCl was faster than in pH 7.3 buffer, resulting from a higher solubility of MZ in acid medium. The modulation of MZ release kinetics from shellac-based matrix tablets could be accomplished by varying the amount of shellac or annealing temperature. The release kinetics was shifted from relaxation-controlled release to diffusion-controlled release when the amount of shellac or the annealing temperature was increased.

  13. Transient fission-product release during reactor shutdown and startup

    International Nuclear Information System (INIS)

    Hunt, C.E.L.; Lewis, B.J.; Dickson, L.W.

    1997-12-01

    Sweep-gas experiments performed at AECL's Chalk River Laboratories from 1979 to 1985 have been further analysed to determine the fraction of the gaseous fission-product inventory that is released on reactor shutdown and startup. Empirical equations were derived and applied to calculate the stable xenon release from companion fuel elements and from a well-documented experimental fuel bundle irradiated in the NRU reactor. The calculated gas release could be matched to the measured values within about a factor of two for an experimental irradiation with a burnup of 217 MWh/kgU. There was also limited information on the fraction of the radioactive iodine that was exposed, but not released, on reactor shutdown. An empirical equation is proposed for calculating this fraction. (author)

  14. Mechanism of Mg2+-Accompanied Product Release in Sugar Nucleotidyltransferases.

    Science.gov (United States)

    Vithani, Neha; Ankush Jagtap, Pravin Kumar; Verma, Sunil Kumar; Tripathi, Ravi; Awasthi, Shalini; Nair, Nisanth N; Prakash, Balaji

    2018-03-06

    The nucleotidyl transfer reaction, catalyzed by sugar nucleotidyltransferases (SNTs), is assisted by two active site Mg 2+ ions. While studying this reaction using X-ray crystallography, we captured snapshots of the pyrophosphate (product) as it exits along a pocket. Surprisingly, one of the active site Mg 2+ ions remains coordinated to the exiting pyrophosphate. This hints at the participation of Mg 2+ in the process of product release, besides its role in catalyzing nucleotidyl transfer. These observations are further supported by enhanced sampling molecular dynamics simulations. Free energy computations suggest that the product release is likely to be rate limiting in SNTs, and the origin of the high free energy barrier for product release could be traced back to the "slow" conformational change of an Arg residue at the exit end of the pocket. These results establish a dual role for Mg 2+ , and propose a general mechanism of product release during the nucleotidyl transfer by SNTs. Copyright © 2018 Elsevier Ltd. All rights reserved.

  15. Fission product release from HTGR coated microparticles and fuel elements

    International Nuclear Information System (INIS)

    Gusev, A.A.; Deryugin, A.I.; Lyutikov, R.A.; Chernikov, A.S.

    1991-01-01

    The article presents the results of the investigation of fission products release from microparticles with UO 2 core and five-layer HII PyC- and SiC base protection layers of TRICO type as well as from spherical fuel elements based thereon. It is shown that relative release of short-lived xenon and crypton from microparticles does not exceed (2-3) 10 -7 . The release of gaseous fission products from fuel elements containing no damaged coated microparticles, is primarily determined by the contamination of matrix graphite with fuel. An analytical dependence is derived, the dependence described the relation between structural parameters of coated microparticles, irradiation conditions and fuel burnup at which depressurization of coated microparticles starts

  16. The market for equity release products: Lessons from the ...

    African Journals Online (AJOL)

    Home Equity Release Products (ERPs) are innovative fi nancial instruments that enable elderly, retired people to use their unencumbered houses as a source of income/funding while they continue to reside in them, thereby seeking to address the constraints of the life cycle hypothesis. The loan and outstanding amounts ...

  17. Fission product release by fuel oxidation after water ingress

    International Nuclear Information System (INIS)

    Schreiber.

    1990-01-01

    On the basis of data obtained by a literature search, a computer code has been established for the calculation of the degree of oxidation of the fuel in the damaged fuel particles, and hence of the fission product release as a function of the time period of steam ingress. (orig.) [de

  18. Kinetic and economic considerations of biogas production systems

    Energy Technology Data Exchange (ETDEWEB)

    Bala, B K; Satter, M A [Bangladesh Agricultural Univ., Mymensingh (BD). Dept. of Farm Power and Machinery

    1990-01-01

    In this paper, the kinetics and economics of substrate degradation and biogas production are discussed. Mass balance on substrate, with either the Contois or Adams-Eckenfelder models, is used to design the mathematical models of volatile solids reduction and biogas fermentation. The predictions of both the models are found to be in close agreement with the observed values reported. A computer model based on a system dynamics approach is used to model the economics of biogas production by anaerobic digestion from cattle slurry available from typical rural families in Bangladesh. This model incorporates the Adams-Eckenfelder model to determine the amount of gas production and the technique described by Audsley and Wheeler to take into account the effects of price, interest, and inflation. The effects of changes of these parameters on the net profit or loss from the process are also considered. (author).

  19. Fission product release from TRIGA-LEU reactor fuels

    International Nuclear Information System (INIS)

    Baldwin, N.L.; Foushee, F.C.; Greenwood, J.S.

    1980-01-01

    Due to present international concerns over nuclear proliferation, TRIGA reactor fuels will utilize only low-enriched uranium (LEU) (enrichment <20%). This requires increased total uranium loading per unit volume of fuel in order to maintain the appropriate fissile loading. Tests were conducted to determine the fractional release of gaseous and metallic fission products from typical uranium-zirconium hydride TRIGA fuels containing up to 45 wt-% uranium. These tests, performed in late 1977 and early 1978, were similar to those conducted earlier on TRIGA fuels with 8.5 wt-% U. Fission gas release measurements were made on prototypic specimens from room temperature to 1100 deg. C in the TRIGA King Furnace Facility. The fuel specimens were irradiated in the TRIGA reactor at a low power level. The fractional releases of the gaseous nuclides of krypton and xenon were measured under steady-state operating conditions. Clean helium was used to sweep the fission gases released during irradiation from the furnace into a standard gas collection trap for gamma counting. The results of these tests on TRIGA-LEU fuel agree well with data from the similar, earlier tests on TRIGA fuel. The correlation used to calculate the release of fission products from 8.5 wt-% U TRIGA fuel applies equally well for U contents up to 45 wt-%. (author)

  20. Kinetic Studies on Microbial Production of Tannase Using Redgram Husk

    OpenAIRE

    S. K. Mohan; T. Viruthagiri; C. Arunkumar

    2015-01-01

    Tannase (tannin acyl hydrolase, E.C.3.1.1.20) is an important hydrolysable enzyme with innumerable applications and industrial potential. In the present study, a kinetic model has been developed for the batch fermentation used for the production of tannase by A.flavus MTCC 3783. Maximum tannase activity of 143.30 U/ml was obtained at 96 hours under optimum operating conditions at 35oC, an initial pH of 5.5 and with an inducer tannic acid concentration of 3% (w/v) for a fe...

  1. Multi-kinetics and site-specific release of gabapentin and flurbiprofen from oral fixed-dose combination: in vitro release and in vivo food effect.

    Science.gov (United States)

    Sonvico, Fabio; Conti, Chiara; Colombo, Gaia; Buttini, Francesca; Colombo, Paolo; Bettini, Ruggero; Barchielli, Marco; Leoni, Barbara; Loprete, Luca; Rossi, Alessandra

    2017-09-28

    In this work, a fixed-dose combination of gabapentin and flurbiprofen formulated as multilayer tablets has been designed, developed and studied in vitro and in vivo. The aim was to construct a single dosage form of the two drugs, able to perform a therapeutic program involving three release kinetics and two delivery sites, i.e., immediate release of gabapentin, intra-gastric prolonged release of gabapentin and intestinal (delayed) release of flurbiprofen. An oblong three-layer tablet was manufactured having as top layer a floating hydrophilic polymeric matrix for gastric release of gabapentin, as middle layer a disintegrating formulation for immediate release of a gabapentin loading dose and as bottom layer, an uncoated hydrophilic polymeric matrix, swellable but insoluble in gastric fluids, for delayed and prolonged release of flurbiprofen in intestinal environment. The formulations were studied in vitro and in vivo in healthy volunteers. The in vitro release rate assessment confirmed the programmed delivery design. A significant higher bioavailability of gabapentin administered 30min after meal, compared to fasting conditions or to dose administration 10min before meal, argued in favor of the gastro-retention of gabapentin prolonged release layer. The two drugs were delivered at different anatomical sites, since the food presence prolonged the gastric absorption of gabapentin from the floating layer and delayed the flurbiprofen absorption. The attainment of a successful delayed release of flurbiprofen was realized by a matrix based on a polymers' combination. The combined use of three hydrophilic polymers with different pH sensitivity provided the dosage form layer containing flurbiprofen with gastro-resistant characteristics without the use of film coating. Copyright © 2017 Elsevier B.V. All rights reserved.

  2. Effective atomic numbers, electron densities and kinetic energy released in matter of vitamins for photon interaction

    Science.gov (United States)

    Shantappa, A.; Hanagodimath, S. M.

    2014-01-01

    Effective atomic numbers, electron densities of some vitamins (Retinol, Riboflavin, Niacin, Biotin, Folic acid, Cobalamin, Phylloquinone and Flavonoids) composed of C, H, O, N, Co, P and S have been calculated for total and partial photon interactions by the direct method for energy range 1 keV-100 GeV by using WinXCOM and kinetic energy released in matter (Kerma) relative to air is calculated in energy range of 1 keV-20 MeV. Change in effective atomic number and electron density with energy is calculated for all photon interactions. Variation of photon mass attenuation coefficients with energy are shown graphically only for total photon interaction. It is observed that change in mass attenuation coefficient with composition of different chemicals is very large below 100 keV and moderate between 100 keV and 10 MeV and negligible above 10 MeV. Behaviour of vitamins is almost indistinguishable except biotin and cobalamin because of large range of atomic numbers from 1(H) to 16 (S) and 1(H) to 27(Co) respectively. K a value shows a peak due to the photoelectric effect around K-absorption edge of high- Z constituent of compound for biotin and cobalamin.

  3. Animal manure phosphorus characterization by sequential chemical fractionation, release kinetics and 31P-NMR analysis

    Directory of Open Access Journals (Sweden)

    Tales Tiecher

    2014-10-01

    Full Text Available Phosphate release kinetics from manures are of global interest because sustainable plant nutrition with phosphate will be a major concern in the future. Although information on the bioavailability and chemical composition of P present in manure used as fertilizer are important to understand its dynamics in the soil, such studies are still scarce. Therefore, P extraction was evaluated in this study by sequential chemical fractionation, desorption with anion-cation exchange resin and 31P nuclear magnetic resonance (31P-NMR spectroscopy to assess the P forms in three different dry manure types (i.e. poultry, cattle and swine manure. All three methods showed that the P forms in poultry, cattle and swine dry manures are mostly inorganic and highly bioavailable. The estimated P pools showed that organic and recalcitrant P forms were negligible and highly dependent on the Ca:P ratio in manures. The results obtained here showed that the extraction of P with these three different methods allows a better understanding and complete characterization of the P pools present in the manures.

  4. Measurement and characterization of fission products released from LWR fuel

    International Nuclear Information System (INIS)

    Osborne, M.F.; Collins, J.L.; Lorenz, R.A.; Norwood, K.S.; Strain, R.V.

    1984-01-01

    Samples of commercial LWR fuel have been heated under simulated accident conditions to determine the extent and the chemical forms of fission product release. This project was sponsored by the USNRC under a broad program of reactor safety studies. Of the five tests discussed, the fractional releases of Kr, I, and Cs varied from approx. 2% at 1400 0 C to >50% at 2000 0 C; much smaller fractions of Ru, Ag, Sb, and Te were measured in some tests. The major chemical forms in the effluent appeared to include CsI, CsOH, Sb, Te, and Ag

  5. Measurement and characterization of fission products released from LWR fuel

    International Nuclear Information System (INIS)

    Osborne, M.F.; Collins, J.L.; Lorenz, R.A.; Norwood, K.S.; Strain, R.V.

    1984-01-01

    Samples of commercial LWR fuel have been heated under simulated accident conditions to determine the extent and the chemical forms of fission product release. Of the five tests discussed, the fractional releases of Kr, I, and Cs varied from proportional 2% at 1400 0 C to >50% at 2000 0 C; much smaller fractions of Ru, Ag, Sb, and Te were measured in some tests. The major chemical forms in the effluent appeared to include CsI, CsOH, Sb, Te, and Ag. (orig./HP)

  6. FREVAP-6, Metal Fission Products Release from HTGR Fuel Elements

    International Nuclear Information System (INIS)

    Pierce, V.H.

    2005-01-01

    1 - Description of problem or function: The FREVAP type of code for estimating the release of longer-lived metallic fission products from HTGR fuel elements has been developed to take into account the combined effects of the retention of metallic fission products by fuel particles and the rather strong absorption of these fission products by the graphite of the fuel elements. Release calculations are made on the basis that the loss of fission product nuclides such as strontium, cesium, and barium is determined by their evaporation from the graphite surfaces and their transpiration induced by the flowing helium coolant. The code is devised so that changes of fission rate (fuel element power), fuel temperature, and graphite temperature may be incorporated into the calculation. Temperature is quite important in determining release because, in general, both release from fuel particles and loss by evaporation (transpiration) vary exponentially with the reciprocal of the absolute temperature. NESC0301/02: This version differs from the previous one in the following points: The source and output files were converted from BCD to ASCII coding. 2 - Method of solution: A problem is defined as having a one-dimensional segment made up of three parts - (1) the fission product source (fuel particles) in series with, (2) a non-source and absorption part (element graphite) and (3) a surface for evaporation to the coolant (graphite-helium interface). More than one segment may be connected (possibly segments stacked axially) by way of the coolant. At any given segment, a continuity equation is solved assuming equilibrium between the source term, absorption term, evaporation at coolant interface and the partial pressure of the fission product isotope in the coolant. 3 - Restrictions on the complexity of the problem - Maxima of: 5 isotopes; 10 time intervals for time-dependent variable; 49 segments (times number of isotopes); 5 different output print time-steps

  7. Kinetic coupling of phosphate release, force generation and rate-limiting steps in the cross-bridge cycle.

    Science.gov (United States)

    Stehle, Robert; Tesi, Chiara

    2017-08-01

    A basic goal in muscle research is to understand how the cyclic ATPase activity of cross-bridges is converted into mechanical force. A direct approach to study the chemo-mechanical coupling between P i release and the force-generating step is provided by the kinetics of force response induced by a rapid change in [P i ]. Classical studies on fibres using caged-P i discovered that rapid increases in [P i ] induce fast force decays dependent on final [P i ] whose kinetics were interpreted to probe a fast force-generating step prior to P i release. However, this hypothesis was called into question by studies on skeletal and cardiac myofibrils subjected to P i jumps in both directions (increases and decreases in [P i ]) which revealed that rapid decreases in [P i ] trigger force rises with slow kinetics, similar to those of calcium-induced force development and mechanically-induced force redevelopment at the same [P i ]. A possible explanation for this discrepancy came from imaging of individual sarcomeres in cardiac myofibrils, showing that the fast force decay upon increase in [P i ] results from so-called sarcomere 'give'. The slow force rise upon decrease in [P i ] was found to better reflect overall sarcomeres cross-bridge kinetics and its [P i ] dependence, suggesting that the force generation coupled to P i release cannot be separated from the rate-limiting transition. The reasons for the different conclusions achieved in fibre and myofibril studies are re-examined as the recent findings on cardiac myofibrils have fundamental consequences for the coupling between P i release, rate-limiting steps and force generation. The implications from P i -induced force kinetics of myofibrils are discussed in combination with historical and recent models of the cross-bridge cycle.

  8. Fission fragment yields and total kinetic energy release in neutron-induced fission of235,238U,and239Pu

    Science.gov (United States)

    Tovesson, F.; Duke, D.; Geppert-Kleinrath, V.; Manning, B.; Mayorov, D.; Mosby, S.; Schmitt, K.

    2018-03-01

    Different aspects of the nuclear fission process have been studied at Los Alamos Neutron Science Center (LANSCE) using various instruments and experimental techniques. Properties of the fragments emitted in fission have been investigated using Frisch-grid ionization chambers, a Time Projection Chamber (TPC), and the SPIDER instrument which employs the 2v-2E method. These instruments and experimental techniques have been used to determine fission product mass yields, the energy dependent total kinetic energy (TKE) release, and anisotropy in neutron-induced fission of U-235, U-238 and Pu-239.

  9. Analysis of hydrogen sulfide releases in heavy water production facilities

    International Nuclear Information System (INIS)

    Croitoru, Cornelia; Dumitrescu, Maria; Preda, Irina; Lazar, Roxana

    1996-01-01

    Safety analyses conducted at ICIS concern primarily the heavy water production installations. The quantitative risk assessment needs the frequency calculation of accident sequences and consequences. In heavy water plants which obtain primary isotopic concentration of water by H 2 O - H 2 S exchange, large amounts of hydrogen sulfide which is a toxic, inflammable and explosive gas, are circulated. The first stage in calculating the consequences consists in potential analysis of H 2 S release. This work presents a study of this types of releases for pilot installations of the heavy water production at ICIS (Plant 'G' at Rm. Valcea). The installations which contain and maneuver large quantities of H 2 S and the mathematical models for different types of releases are presented. The accidents analyzed are: catastrophic column, container, spy-hole failures or gas-duct rupture and wall cracks in the installation. The main results are given as tables while the time variations of the flow rate and quantities of H 2 O released by stack disposal are plotted

  10. Pharmaceutical Product Lead Optimization for Better In vivo Bioequivalence Performance: A case study of Diclofenac Sodium Extended Release Matrix Tablets.

    Science.gov (United States)

    Shahiwala, Aliasgar; Zarar, Aisha

    2018-01-01

    In order to prove the validity of a new formulation, a considerable amount of effort is required to study bioequivalence, which not only increases the burden of carrying out a number of bioequivalence studies but also eventually increases the cost of the optimization process. The aim of the present study was to develop sustained release matrix tablets containing diclofenac sodium using natural polymers and to demonstrate step by step process of product development till the prediction of in vivo marketed product equivalence of the developed product. Different batches of tablets were prepared by direct compression. In vitro drug release studies were performed as per USP. The drug release data were assessed using model-dependent, modelindependent and convolution approaches. Drug release profiles showed that extended release action were in the following order: Gum Tragacanth > Sodium Alginate > Gum Acacia. Amongst the different batches prepared, only F1 and F8 passed the USP criteria of drug release. Developed formulas were found to fit Higuchi kinetics model with Fickian (case I) diffusion-mediated release mechanism. Model- independent kinetics confirmed that total of four batches were passed depending on the similarity factors based on the comparison with the marketed Diclofenac. The results of in vivo predictive convolution model indicated that predicted AUC, Cmax and Tmax values for batch F8 were similar to that of marketed product. This study provides simple yet effective outline of pharmaceutical product development process that will minimize the formulation development trials and maximize the product success in bioequivalence studies. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  11. Simulation of Zinc Release Affected by Microbial Inoculation and Salinity Levels in a non-sterile Calcareous Soil Using kinetic Models

    Directory of Open Access Journals (Sweden)

    hamidreza boostani

    2017-02-01

    Full Text Available Introduction: Zinc (Zn is an important nutrient element for humans and plants that controls many biochemical and physiological functions of living organisms. Zinc deficiency is common in high pH, low organic matter, carbonatic, saline and sodic soils. Salinity is a major abiotic environmental stresses that limits growth and production in arid and semi-arid regions of the world. Bioavailability of Zn is low in calcareous and saline soils having high levels of pH and calcium. Desorption of Zinc (Zn from soil as influenced by biological activities is one of the important factors that control Zn bioavailability. Few reports on the effects of salinity on the availability and desorption kinetics of Zn are available. Rupa et al. (2000 reported that increasing the salt concentration led to increase Zn desorption from soil due to ion competition on soil exchangeable sites. Different kinetic equations have been used to describe the release kinetics of nutrients. Reyhanitabar and Gilkes (2010 found that the power function model was the best equation to describe the release of Zn from some calcareous soil of Iran, whereas Baranimotlagh and Gholami (2013 stated that the best model for describing Zn desorption from 15 calcareous soils of Iran was the first-order equation.less attention has been paid to kinetics of Zn release by DTPA extractant over time by inoculation of plant growth promoting rhizobacteria and mycorrhizae fungi in comination with soil salinity.The objective of this study was to evaluate the effect of plant growth promoting rhizobacteria (PGPR and mycorrhizae fungi (MF inoculation on release kinetic of Zn in a calcareous soil at different salinity levels after in cornplantation Materials and Methods: A composite sample of bulk soil from the surface horizon (0-30 cm of a calcareous soil from southern part of Iran was collected, air dried, passed through 2 mm sieve, and thoroughly mixed. Routine soil analysis was performed to determine some

  12. Tracking of fission products release during refueling operations

    International Nuclear Information System (INIS)

    Agarwal, Sharad; Prajapat, M.K.; Vyas, Shyam; Hussain, S.A.

    2001-01-01

    It has been always observed that the release of fission products increase during refueling operations. At RAPP-3 and 4 an attempt has been made to follow-up the change in fission products activity release at each stage of refueling operation and quantification of concentrations of various radionuclides. This exercise was also extended to refueling operation of the channels containing suspected failed fuel. A level of FPNG ( 133 Xe) was observed to increase by a factor of about 10-40 during refueling of failed channel as compared to healthy channel. It can be concluded that by monitoring FPNG levels in exhaust status of the healthiness of spent fuel can be found out. This report discusses in detail the experiment conducted for this purpose. (author)

  13. Performance and first results of fission product release and transport provided by the VERDON facility

    Energy Technology Data Exchange (ETDEWEB)

    Gallais-During, A., E-mail: annelise.gallais-during@cea.fr [CEA, DEN, DEC, F-13108 Saint-Paul-lez-Durance (France); Bonnin, J.; Malgouyres, P.-P. [CEA, DEN, DEC, F-13108 Saint-Paul-lez-Durance (France); Morin, S. [IRSN, F-13108 Saint-Paul-lez-Durance (France); Bernard, S.; Gleizes, B.; Pontillon, Y.; Hanus, E.; Ducros, G. [CEA, DEN, DEC, F-13108 Saint-Paul-lez-Durance (France)

    2014-10-01

    Highlights: • A new facility to perform experimental LWR severe accidents sequences is evaluated. • In the furnace a fuel sample is heated up to 2600 °C under a controlled gas atmosphere. • Innovative thermal gradient tubes are used to study fission product transport. • The new VERDON facility shows an excellent consistency with results from VERCORS. • Fission product re-vapourization results confirm the correct functioning of the gradient tubes. - Abstract: One of the most important areas of research concerning a hypothetical severe accident in a light water reactor (LWR) is determining the source term, i.e. quantifying the nature, release kinetics and global released fraction of the fission products (FPs) and other radioactive materials. In line with the former VERCORS programme to improve source term estimates, the new VERDON laboratory has recently been implemented at the CEA Cadarache Centre in the LECA-STAR facility. The present paper deals with the evaluation of the experimental equipment of this new VERDON laboratory (furnace, release and transport loops) and demonstrates its capability to perform experimental sequences representative of LWR severe accidents and to supply the databases necessary for source term assessments and FP behaviour modelling.

  14. Morphogen and proinflammatory cytokine release kinetics from PRGF-Endoret fibrin scaffolds: evaluation of the effect of leukocyte inclusion.

    Science.gov (United States)

    Anitua, E; Zalduendo, M M; Prado, R; Alkhraisat, M H; Orive, G

    2015-03-01

    The potential influence of leukocyte incorporation in the kinetic release of growth factors from platelet-rich plasma (PRP) may explain the conflicting efficiency of leukocyte platelet-rich plasma (L-PRP) scaffolds in tissue regeneration. To assess this hypothesis, leukocyte-free (PRGF-Endoret) and L-PRP fibrin scaffolds were prepared, and both morphogen and proinflammatory cytokine release kinetics were analyzed. Clots were incubated with culture medium to monitor protein release over 8 days. Furthermore, the different fibrin scaffolds were morphologically characterized. Results show that leukocyte-free fibrin matrices were homogenous while leukocyte-containing ones were heterogeneous, loose and cellular. Leukocyte incorporation produced a significant increase in the contents of proinflammatory cytokines interleukin (IL)-1β and IL-16 but not in the platelet-derived growth factors release (PRGF-Endoret, the inclusion of leukocytes induced a major increase in these cytokines, which was characterized by the presence of a latent period. The PRGF-Endoret matrices were stable during the 8 days of incubation. The inclusion of leukocytes alters the growth factors release profile and also increased the dose of proinflammatory cytokines. © 2014 Wiley Periodicals, Inc.

  15. A method for measurements of neutral fragments kinetic energies released to a specific dissociation threshold: optical translational spectroscopy

    International Nuclear Information System (INIS)

    Roney, A.; Frigon, C.; Larzilliere, M.

    1999-01-01

    The optical translational spectroscopy technique, based on the principles of fast ion beam laser spectroscopy (FIBLAS) and translational spectroscopy, allows the kinetic energies study of neutral fragments released through free dissociation of a neutral molecule. This method presents interesting features such as near-threshold energy measurements and selection of a specific dissociation limit. The fragments resulting from free dissociation (not induced) of neutral molecules, produced by charge exchange processes with a fast ion beam, are probed by laser radiation. Monitoring of the laser-induced fluorescence allows high-resolution spectra due to the kinematic compression of the velocity spread. Measurements of kinetic energies released to the second limit of dissociation H(1s) + H(2l) of H 2 are put forth and compared with those obtained by means of off-axis translational spectroscopy

  16. Modeling texture kinetics during thermal processing of potato products.

    Science.gov (United States)

    Moyano, P C; Troncoso, E; Pedreschi, F

    2007-03-01

    A kinetic model based on 2 irreversible serial chemical reactions has been proposed to fit experimental data of texture changes during thermal processing of potato products. The model links dimensionless maximum force F*(MAX) with processing time. Experimental texture changes were obtained during frying of French fries and potato chips at different temperatures, while literature data for blanching/cooking of potato cubes have been considered. A satisfactory agreement between experimental and predicted values was observed, with root mean square values (RMSs) in the range of 4.7% to 16.4% for French fries and 16.7% to 29.3% for potato chips. In the case of blanching/cooking, the proposed model gave RMSs in the range of 1.2% to 17.6%, much better than the 6.2% to 44.0% obtained with the traditional 1st-order kinetics. The model is able to predict likewise the transition from softening to hardening of the tissue during frying.

  17. Production of ascorbic acid releasing biomaterials for pelvic floor repair.

    Science.gov (United States)

    Mangır, Naşide; Bullock, Anthony J; Roman, Sabiniano; Osman, Nadir; Chapple, Christopher; MacNeil, Sheila

    2016-01-01

    An underlying abnormality in collagen turnover is implied in the occurrence of complications and recurrences after mesh augmented pelvic floor repair surgeries. Ascorbic acid is a potent stimulant of collagen synthesis. The aim of this study is to produce ascorbic acid releasing poly-lactic acid (PLA) scaffolds and evaluate them for their effects on extracellular matrix production and the strength of the materials. Scaffolds which contained either l-ascorbic acid (AA) and Ascorbate-2-Phosphate (A2P) were produced with emulsion electrospinning. The release of both drugs was measured by UV spectrophotometry. Human dermal fibroblasts were seeded on scaffolds and cultured for 2weeks. Cell attachment, viability and total collagen production were evaluated as well as mechanical properties. No significant differences were observed between AA, A2P, Vehicle and PLA scaffolds in terms of fibre diameter and pore size. The encapsulation efficiency and successful release of both AA and A2P were demonstrated. Both AA and A2P containing scaffolds were significantly more hydrophilic and stronger in both dry and wet states compared to PLA scaffolds. Fibroblasts produced more collagen on scaffolds containing either AA or A2P compared to cells grown on control scaffolds. This study is the first to directly compare the two ascorbic acid derivatives in a tissue engineered scaffold and shows that both AA and A2P releasing electrospun PLA scaffolds increased collagen production of fibroblasts to similar extents but AA scaffolds seemed to be more hydrophilic and stronger compared to A2P scaffolds. Mesh augmented surgical repair of the pelvic floor currently relies on non-degradable materials which results in severe complications in some patients. There is an unmet and urgent need for better pelvic floor repair materials. Our current understanding suggests that the ideal material should be able to better integrate into sites of implantation both biologically and mechanically. The impact of

  18. Carrageenan-based semi-IPN nanocomposite hydrogels: Swelling kinetic and slow release of sequestrene Fe 138 fertilizer

    Directory of Open Access Journals (Sweden)

    Mohammad Kazem Bahrami

    2016-09-01

    Full Text Available Nanocomposite hydrogels based on kappa-carrageenan were synthesized by incorporating natural sodium montmorillonite (Cloisite nanoclay. Acrylamide (AAm and methylenebisacrylamide (MBA were used as a monomer and a crosslinker, respectively. Effects of reaction variables on the swelling kinetics were studied. The results revealed that the rate of swelling for nanocomposites with high content of MBA was higher than those of nanocomposites consisting of low content of MBA. Similar to the effect of MBA, the rate of swelling enhanced as the carrageenan content was decreased. The influence of clay content on swelling rate was not remarkable. The experimental swelling data were evaluated by pseudo-first-order and pseudo-second-order kinetic models. The swelling data described well by pseudo-second-order kinetic model. Sequestrene Fe 138 (Sq as an agrochemical was loaded into nanocomposites and releasing of this active agent from nanocomposites was studied. The clay-free hydrogel released the whole loaded Sq; whereas the presence of clay restricted the release of Sq.

  19. Impact of human milk pasteurization on the kinetics of peptide release during in vitro dynamic term newborn digestion.

    Science.gov (United States)

    Deglaire, Amélie; De Oliveira, Samira C; Jardin, Julien; Briard-Bion, Valérie; Emily, Mathieu; Ménard, Olivia; Bourlieu, Claire; Dupont, Didier

    2016-07-01

    Holder pasteurization (62.5°C, 30 min) ensures sanitary quality of donor's human milk but also denatures beneficial proteins. Understanding whether this further impacts the kinetics of peptide release during gastrointestinal digestion of human milk was the aim of the present paper. Mature raw (RHM) or pasteurized (PHM) human milk were digested (RHM, n = 2; PHM, n = 3) by an in vitro dynamic system (term stage). Label-free quantitative peptidomics was performed on milk and digesta (ten time points). Ascending hierarchical clustering was conducted on "Pasteurization × Digestion time" interaction coefficients. Preproteolysis occurred in human milk (159 unique peptides; RHM: 91, PHM: 151), mostly on β-casein (88% of the endogenous peptides). The predicted cleavage number increased with pasteurization, potentially through plasmin activation (plasmin cleavages: RHM, 53; PHM, 76). During digestion, eight clusters resumed 1054 peptides from RHM and PHM, originating for 49% of them from β-casein. For seven clusters (57% of peptides), the kinetics of peptide release differed between RHM and PHM. The parent protein was significantly linked to the clustering (p-value = 1.4 E-09), with β-casein and lactoferrin associated to clusters in an opposite manner. Pasteurization impacted selectively gastric and intestinal kinetics of peptide release in term newborns, which may have further nutritional consequences. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Effect Of Ether Derivative Cellulose Polymers On Hydration, Erosion And Release Kinetics Of Diclofenac Sodium Matrix Tablets

    Directory of Open Access Journals (Sweden)

    Muhammad Akhlaq*1,2, Gul Majid Khan1 , Abdul Wahab1, Waqas Rabbani1, Abid Hussain1, Asif Nawaz1, & Alam Zeb1

    2011-09-01

    Full Text Available Objectives: The work aims to investigate the effect ofhydrophilic and hydrophobic polymers swelling and erosionon the release behaviour of DCL-Na from controlled matrixtablets prepared by direct compression and wet-granulationtechniques.Materials and Methods: Powder preformulation studies wereconducted. Tablets were prepared by direct compressiontechnique and their physicochemical properties wereevaluated. Drug-polymer interaction was analyzed by FTIRspectroscopy. The in-vitro drug release study was conductedusing phosphte buffer pH 7.4 as dissolution medium anddifferent kinetic parameters were applied.Results and Discussion: F-1 and F-5 containing ethycelluloseprepared by direct compression and wet granulationtechniques released 94 % and 84 % drug after 24hrs, while F-2and F-6 containing hydroxypropylmethylcellulose polymerprepared by direct compression and wet granulation released98.46 % and 91.25 % drug after within 24 hrs respectively.Ethylcellulose and hydroxypropylmethylcellulose based matrixtablets showed the best anomalous drug release behaviour,with the release exponents “ n ” ranging from 0.685 to 0.809.Conclusion: It has been concluded that ethylcellulose etherderivative polymer is used to prepare oral controlled releasematrix tablet of diclofenac sodium. Fickian drug diffusion,polymer hydration and erosion mechanisms occurredsimultaneously and were considered as the main drug releasecontrolling factors.

  1. The load and release characteristics on a strong cationic ion-exchange fiber: kinetics, thermodynamics, and influences.

    Science.gov (United States)

    Yuan, Jing; Gao, Yanan; Wang, Xinyu; Liu, Hongzhuo; Che, Xin; Xu, Lu; Yang, Yang; Wang, Qifang; Wang, Yan; Li, Sanming

    2014-01-01

    Ion-exchange fibers were different from conventional ion-exchange resins in their non-cross-linked structure. The exchange was located on the surface of the framework, and the transport resistance reduced significantly, which might mean that the exchange is controlled by an ionic reaction instead of diffusion. Therefore, this work aimed to investigate the load and release characteristics of five model drugs with the strong cationic ion-exchange fiber ZB-1. Drugs were loaded using a batch process and released in United States Pharmacopoeia (USP) dissolution apparatus 2. Opposing exchange kinetics, suitable for the special structure of the fiber, were developed for describing the exchange process with the help of thermodynamics, which illustrated that the load was controlled by an ionic reaction. The molecular weight was the most important factor to influence the drug load and release rate. Strong alkalinity and rings in the molecular structures made the affinity between the drug and fiber strong, while logP did not cause any profound differences. The drug-fiber complexes exhibited sustained release. Different kinds and concentrations of counter ions or different amounts of drug-fiber complexes in the release medium affected the release behavior, while the pH value was independent of it. The groundwork for in-depth exploration and further application of ion-exchange fibers has been laid.

  2. Kinetic study and syngas production from pyrolysis of forestry waste

    International Nuclear Information System (INIS)

    Hu, Mian; Wang, Xun; Chen, Jian; Yang, Ping; Liu, Cuixia; Xiao, Bo; Guo, Dabin

    2017-01-01

    Highlights: • Pyrolysis process can be divided into three stages using differential DTG method. • A modified discrete DAEM model fitted experimental data well. • Fe/biochar catalyst showed a good performance on catalytic reforming process. - Abstract: Kinetic study and syngas production from pyrolysis of forestry waste (pine sawdust (PS)) were investigated using a thermogravimetric analyzer (TGA) and a fixed-bed reactor, respectively. In TGA, it was found that the pyrolysis of PS could be divided into three stages and stage II was the major mass reduction stage with mass loss of 73–74%. The discrete distributed activation energy model (DAEM) with discrete 200 first-order reactions was introduced to study the pyrolysis kinetic. The results indicated that the DAEM with 200 first-order reactions could approximate the pyrolysis process with an excellent fit between experimental and calculated data. The apparent activation energies of PS ranged from 147.86 kJ·mol −1 to 395.76 kJ·mol −1 , with corresponding pre-exponential factors of 8.30 × 10 13 s −1 to 3.11 × 10 25 s −1 . In the fixed-bed reactor, char supported iron catalyst was prepared for tar cracking. Compared with no catalyst which the gas yield and tar yield were 0.58 N m 3 /kg biomass and 201.23 g/kg biomass, the gas yield was markedly increased to 1.02 N m 3 /kg biomass and the tar yield was decreased to only 26.37 g/kg biomass in the presence of char supported iron catalyst. These results indicated that char supported iron catalyst could potentially be used to catalytically decompose tar molecules in syngas generated via biomass pyrolysis.

  3. Controlled Release Kinetics in Hydroxy Double Salts: Effect of Host Anion Structure

    Directory of Open Access Journals (Sweden)

    Stephen Majoni

    2014-01-01

    Full Text Available Nanodimensional layered metal hydroxides such as layered double hydroxides (LDHs and hydroxy double salts (HDSs can undergo anion exchange reactions releasing intercalated anions. Because of this, these metal hydroxides have found applications in controlled release delivery of bioactive species such as drugs and pesticides. In this work, isomers of hydroxycinnamate were used as model compounds to systematically explore the effects of anion structure on the rate and extent of anion release in HDSs. Following intercalation and subsequent release of the isomers, it has been demonstrated that the nature and position of substituent groups on intercalated anions have profound effects on the rate and extent of release. The extent of release was correlated with the magnitude of dipole moments while the rate of reaction showed strong dependence on the extent of hydrogen bonding within the layers. The orthoisomer showed a more sustained and complete release as compared to the other isomers.

  4. Fission product release from defected nuclear reactor fuel elements

    International Nuclear Information System (INIS)

    Lewis, B.J.

    1983-01-01

    The release of gaseous (krypton and xenon) and iodine radioactive fission products from defective fuel elements is described with a semi-empirical model. The model assumes precursor-corrected 'Booth diffusional release' in the UO 2 and subsequent holdup in the fuel-to-sheath gap. Transport in the gap is separately modelled with a phenomenological rate constant (assuming release from the gap is a first order rate process), and a diffusivity constant (assuming transport in the gap is dominated by a diffusional process). Measured release data from possessing various states of defection are use in this analysis. One element (irradiated in an earlier experiment by MacDonald) was defected with a small drilled hole. A second element was machined with 23 slits while a third element (fabricated with a porous end plug) displayed through-wall sheath hydriding. Comparison of measured release data with calculated values from the model yields estimates of empirical diffusion coefficients for the radioactive species in the UO 2 (1.56 x 10 -10 to 7.30 x 10 -9 s -1 ), as well as escape rate constants (7.85 x 10 -7 to 3.44 x 10 -5 s -1 ) and diffusion coefficients (3.39 x 10 -5 to 4.88 x 10 -2 cm 2 /s) for these in the fuel-to-sheath gap. Analyses also enable identification of the various rate-controlling processes operative in each element. For the noble gas and iodine species, the rate-determining process in the multi-slit element is 'Booth diffusion'; however, for the hydrided element an additional delay results from diffusional transport in the fuel-to-heath gap. Furthermore, the iodine species exhibit an additional holdup in the drilled element because of significant trapping on the fuel and/or sheath surfaces. Using experimental release data and applying the theoretical results of this work, a systematic procedure is proposed to characterize fuel failures in commercial power reactors (i.e., the number of fuel failures and average leak size)

  5. Defining the Structural Basis for Allosteric Product Release from E. coli Dihydrofolate Reductase Using NMR Relaxation Dispersion.

    Science.gov (United States)

    Oyen, David; Fenwick, R Bryn; Aoto, Phillip C; Stanfield, Robyn L; Wilson, Ian A; Dyson, H Jane; Wright, Peter E

    2017-08-16

    The rate-determining step in the catalytic cycle of E. coli dihydrofolate reductase is tetrahydrofolate (THF) product release, which can occur via an allosteric or an intrinsic pathway. The allosteric pathway, which becomes accessible when the reduced cofactor NADPH is bound, involves transient sampling of a higher energy conformational state, greatly increasing the product dissociation rate as compared to the intrinsic pathway that obtains when NADPH is absent. Although the kinetics of this process are known, the enzyme structure and the THF product conformation in the transiently formed excited state remain elusive. Here, we use side-chain proton NMR relaxation dispersion measurements, X-ray crystallography, and structure-based chemical shift predictions to explore the structural basis of allosteric product release. In the excited state of the E:THF:NADPH product release complex, the reduced nicotinamide ring of the cofactor transiently enters the active site where it displaces the pterin ring of the THF product. The p-aminobenzoyl-l-glutamate tail of THF remains weakly bound in a widened binding cleft. Thus, through transient entry of the nicotinamide ring into the active site, the NADPH cofactor remodels the enzyme structure and the conformation of the THF to form a weakly populated excited state that is poised for rapid product release.

  6. Release of fission products from contaminated sodium fires

    International Nuclear Information System (INIS)

    Jordan, S.

    1976-01-01

    Leaks in the primary coolant system of a LMFBR and also serious incidents with tank rupture may entail the escape of fission products into the containment of the reactor. For incident analysis it is important to know the retention capability of sodium for the different fission products. The release of cesium and strontium from pools contaminated with 100 to 1000 ppM was investigated by experiments. The cesium content of airborne aerosols depends on oxygen concentration: at 21 percent oxygen concentration the Cs content of sodium-oxide aerosols is 3 times and at 0.5 percent 15 times as high as the initial Cs concentration in the pool. Strontium content of aerosols over burning contaminated sodium pools is 10 3 times smaller than the strontium pool concentration

  7. Fission Product Release from Spent Nuclear Fuel During Melting

    International Nuclear Information System (INIS)

    Howell, J.P.; Zino, J.F.

    1998-09-01

    The Melt-Dilute process consolidates aluminum-clad spent nuclear fuel by melting the fuel assemblies and diluting the 235U content with depleted uranium to lower the enrichment. During the process, radioactive fission products whose boiling points are near the proposed 850 degrees C melting temperature can be released. This paper presents a review of fission product release data from uranium-aluminum alloy fuel developed from Severe Accident studies. In addition, scoping calculations using the ORIGEN-S computer code were made to estimate the radioactive inventories in typical research reactor fuel as a function of burnup, initial enrichment, and reactor operating history and shutdown time.Ten elements were identified from the inventory with boiling points below or near the 850 degrees C reference melting temperature. The isotopes 137Cs and 85Kr were considered most important. This review serves as basic data to the design and development of a furnace off-gas system for containment of the volatile species

  8. Kinetics of phosphorus and potassium release from rock phosphate and waste mica enriched compost and their effect on yield and nutrient uptake by wheat (Triticum aestivum).

    Science.gov (United States)

    Nishanth, D; Biswas, D R

    2008-06-01

    An attempt was made to study the efficient use of rice straw and indigenous source of phosphorus and potassium in crop production through composting technology. Various enriched composts were prepared using rice straw, rock phosphate (RP), waste mica and bioinoculant (Aspergillus awamori) and kinetics of release of phosphorus and potassium from enriched composts and their effect on yield and nutrient uptake by wheat (Triticum aestivum) were carried out. Results showed sharp increases in release in water-soluble P and K from all the composts at 8th to 12th day of leaching, thereafter, it decreased gradually. Maximum release of water-soluble P and K were obtained in ordinary compost than enriched composts during the initial stages of leaching, but their differences narrowed down at latter stages. Data in pot experiments revealed that enriched composts performed poorly than diammonium phosphate during initial stages of crop growth, but they out yielded at the latter stages, particularly at maturity stage, as evident from their higher yield, uptake, nutrient recoveries and fertility status of P and K in soils. Moreover, enriched composts prepared with RP and waste mica along with A. awamori resulted in significantly higher biomass yield, uptake and recoveries of P and K as well as available P and K in soils than composts prepared without inoculant. Results indicated that enriched compost could be an alternate technology for the efficient management of rice straw, low-grade RP and waste mica in crop production, which could help to reduce the reliance on costly chemical fertilizers.

  9. Implementation of Releasing Time to Care - the productive ward.

    Science.gov (United States)

    Wilson, Gwyneth

    2009-07-01

    This paper describes the implementation of the NHS Institute for Innovation and Improvement Productive Ward - releasing time to care programme. It will discuss the benefits and key successes and provides advice for those wishing to implement the programme. In Lord Darzi's Next Stage Review, he advocates an ambitious vision of patient centred - clinician led, locally driven NHS. The Releasing Time to Care programme is a unique opportunity for everyone working within the NHS to improve effectiveness, safety and reliability of the services we provide. Whilst being situated within a National Health Service policy environment learning from this work can be translated nationally and internationally, as the principles underpin the provision of high quality care. Evaluation is currently in relation to each of the 15 modules rather than as the programme as a whole. It uses various methods including audit, observation, activity follow through, satisfaction surveys and process mapping. Each month data is colated for each of the 11 metrics which has shown a reduction in falls, drug administration errors and improvement in the recording of patient observations. One of the key issues is that an essential component for the success of the programme lies in the tangible support of the Trust Board/Board of Directors. Evidence shows that this programme improves patient satisfaction as it enables the provision of an increase in direct patient care by staff and subsequently improved clinical and safety outcomes. Ward Sister/Charge Nurse development includes Leadership, Project management and Lean Methodology techniques. The Releasing Time to Care programme is a key component of the Next Stage Review. It will create productive organisations by being a catalyst for the transformation of Trust services, enabling staff to spend more time caring for patients and users. This release in time will result in better outcomes and subsequent improvement with patient and staff satisfaction and

  10. Kinetic modeling of cell metabolism for microbial production.

    Science.gov (United States)

    Costa, Rafael S; Hartmann, Andras; Vinga, Susana

    2016-02-10

    Kinetic models of cellular metabolism are important tools for the rational design of metabolic engineering strategies and to explain properties of complex biological systems. The recent developments in high-throughput experimental data are leading to new computational approaches for building kinetic models of metabolism. Herein, we briefly survey the available databases, standards and software tools that can be applied for kinetic models of metabolism. In addition, we give an overview about recently developed ordinary differential equations (ODE)-based kinetic models of metabolism and some of the main applications of such models are illustrated in guiding metabolic engineering design. Finally, we review the kinetic modeling approaches of large-scale networks that are emerging, discussing their main advantages, challenges and limitations. Copyright © 2015 Elsevier B.V. All rights reserved.

  11. Kinetic release studies of nitrogen-containing bisphosphonate fromgum acacia crosslinked hydrogels

    CSIR Research Space (South Africa)

    Aderibigbe, BA

    2014-11-01

    Full Text Available on the release mechanism of nitrogen-containing bisphosphonate (BP) wasstudied at pH 1.2 and 7.4. The hydrogels exhibited high swelling ratios at pH 7.4 and low swelling ratiosat pH 1.2. The release study was performed using UV–Visible spectroscopy via complex...

  12. Formulation development and optimization of sustained release matrix tablet of Itopride HCl by response surface methodology and its evaluation of release kinetics.

    Science.gov (United States)

    Bose, Anirbandeep; Wong, Tin Wui; Singh, Navjot

    2013-04-01

    The objective of this present investigation was to develop and formulate sustained release (SR) matrix tablets of Itopride HCl, by using different polymer combinations and fillers, to optimize by Central Composite Design response surface methodology for different drug release variables and to evaluate drug release pattern of the optimized product. Sustained release matrix tablets of various combinations were prepared with cellulose-based polymers: hydroxy propyl methyl cellulose (HPMC) and polyvinyl pyrolidine (pvp) and lactose as fillers. Study of pre-compression and post-compression parameters facilitated the screening of a formulation with best characteristics that underwent here optimization study by response surface methodology (Central Composite Design). The optimized tablet was further subjected to scanning electron microscopy to reveal its release pattern. The in vitro study revealed that combining of HPMC K100M (24.65 MG) with pvp(20 mg)and use of LACTOSE as filler sustained the action more than 12 h. The developed sustained release matrix tablet of improved efficacy can perform therapeutically better than a conventional tablet.

  13. Atmospheric degradation of 3-methylfuran: kinetic and products study

    Directory of Open Access Journals (Sweden)

    A. Tapia

    2011-04-01

    Full Text Available A study of the kinetics and products obtained from the reactions of 3-methylfuran with the main atmospheric oxidants has been performed. The rate coefficients for the gas-phase reaction of 3-methylfuran with OH and NO3 radicals have been determined at room temperature and atmospheric pressure (air and N2 as bath gases, using a relative method with different experimental techniques. The rate coefficients obtained for these reactions were (in units cm3 molecule−1 s−1 kOH = (1.13 ± 0.22 × 10−10 and kNO3 = (1.26 ± 0.18 × 10−11. Products from the reaction of 3-methylfuran with OH, NO3 and Cl atoms in the absence and in the presence of NO have also been determined. The main reaction products obtained were chlorinated methylfuranones and hydroxy-methylfuranones in the reaction of 3-methylfuran with Cl atoms, 2-methylbutenedial, 3-methyl-2,5-furanodione and hydroxy-methylfuranones in the reaction of 3-methylfuran with OH and NO3 radicals and also nitrated compounds in the reaction with NO3 radicals. The results indicate that, in all cases, the main reaction path is the addition to the double bond of the aromatic ring followed by ring opening in the case of OH and NO3 radicals. The formation of 3-furaldehyde and hydroxy-methylfuranones (in the reactions of 3-methylfuran with Cl atoms and NO3 radicals confirmed the H-atom abstraction from the methyl group and from the aromatic ring, respectively. This study represents the first product determination for Cl atoms and NO3 radicals in reactions with 3-methylfuran. The reaction mechanisms and atmospheric implications of the reactions under consideration are also discussed.

  14. Soluble microbial products (SMPs release in activated sludge systems: a review

    Directory of Open Access Journals (Sweden)

    Azami Hamed

    2012-12-01

    Full Text Available Abstract This review discusses the characterization, production and implications of soluble microbial products (SMPs in biological wastewater treatment. The precise definition of SMPs is open to talk about, but is currently regarded as “the pool of organic compounds that are released into solution from substrate metabolism and biomass decay”'. Some of the SMPs have been identified as humic acids, polysaccharides, proteins, amino acids, antibiotics, extracellular enzymes and structural components of cells and products of energy metabolism. They adversely affect the kinetic activity, flocculating and settling properties of sludge. This review outlines some important findings with regard to biodegradability and treatability of SMPs and also the effect of process parameters on their production. As SMPs are produced during biological treatment process, their trace amounts normally remain in the effluent that defines the highest COD removal efficiency. Their presence in effluent represents a high potential risk of toxic by-product formation during chlorine disinfection. Studies have indicated that among all wastewater post-treatment processes, the adsorption by granular activated carbon combined with biologically induced degradation is the most effective method for removal of SMPs. However, it may be concludes that the knowledge regarding SMPs is still under progress and more work is required to fully understand their contribution to the treatment process.

  15. Soluble Microbial Products (SMPs Release in Activated Sludge Systems: a Review

    Directory of Open Access Journals (Sweden)

    Hamed Azami

    2012-12-01

    Full Text Available This review discusses the characterization, production and implications of soluble microbial products (SMPs in biological wastewater treatment. The precise definition of SMPs is open to talk about, but is currently regarded as “the pool of organic compounds that are released into solution from substrate metabolism and biomass decay”'.Some of the SMPs have been identified as humic acids, olysaccharides, proteins, amino acids, antibiotics,extracellular enzymes and structural components of cells and products of energy metabolism. They adversely affect the kinetic activity, flocculating and settling properties of sludge. This review outlines some important findings with regard to biodegradability and treatability of SMPs and also the effect of process parameters on their production.As SMPs are produced during biological treatment process, their trace amounts normally remain in the effluent that defines the highest COD removal efficiency. Their presence in effluent represents a high potential risk of toxic by-product formation during chlorine disinfection. Studies have indicated that among all wastewaterpost-treatment processes, the adsorption by granular activated carbon combined with biologically induced degradation is the most effective method for removal of SMPs. However, it may be concludes that the knowledge regarding SMPs is still under progress and more work is required to fully understand their contribution to the treatment process.

  16. Transport and release of fission products during nuclear reactor accident

    International Nuclear Information System (INIS)

    Lee, K.W.; Kuhlman, M.R.; Gieseke, J.A.

    1984-01-01

    This study represents the identification and formulation of a systematic, mechanistic approach to estimating source terms and the implementation of this approach through calculations of fission products release to the environment for a large PWR reactor under a selected set of accident conditions. The development and improvement of calculational procedures is an evolutionary process and in the long term must be verified through experimental studies. It is anticipated that as additional information is obtained the accuracy of predictions can be improved and uncertainties reduced. Transport and deposition of radionuclides were found to be quite dependent on the accident sequences and the corresponding thremal hydraulic conditions. Reduced temperatures led to increased deposition of vapor species, and reduced flow rates to increased aerosol deposition. It is to be recognized that the estimates of release fractions are subject to uncertainties in the data and computer models employed in the calculations and are expected to have been influenced by assumptions regarding plant geometry, thermal hydraulics, deposition mechanisms, and sequence events. The effects of these assumptions will be investigated as this study continues. (Author)

  17. Fission product release from core-concrete mixtures

    International Nuclear Information System (INIS)

    Roche, M.F.; Settle, J.; Leibowitz, L.; Johnson, C.E.; Ritzman, R.L.

    1988-01-01

    The objective of this research is to measure the amount of strontium, barium, and lanthanum that is vaporized from core-concrete mixtures. The measurements are being done using a transpiration method. Mixtures of limestone-aggregated concrete, urania doped with a small amount of La, Sr, Ba, and Zr oxides, and stainless steel were vaporized at 2150 K from a zirconia crucible into flowing He-6% H 2 -0.06% H 2 O (a partial molar free energy of oxygen of -420 kJ). The amounts that were vaporized was determined by weight change and by chemical analyses on condensates. The major phases present in the mixture were inferred from electron probe microanalysis (EPM). They were: (1) urania containing calcia and zirconia, (2) calcium zirconate, (3) a calcium magnesium silicate, and (4) magnesia. About 10% of the zirconia crucible was dissolved by the concrete-urania mixture during the experiment, which accounts for the presence of zirconia-containing major phases. To circumvent the problem of zirconia dissolution, we repeated the experiments using mixtures of the limestone-aggregate concrete and the doped urania in molybdenum crucibles. These studies show that thermodynamic calculations of the release of refractory fission products will yield release fractions that are a factor of sixteen too high if the effects of zirconate formation are ignored

  18. Tailoring the degradation rate and release kinetics from poly(galactitol sebacate) by blending with chitosan, alginate or ethyl cellulose.

    Science.gov (United States)

    Natarajan, Janeni; Madras, Giridhar; Chatterjee, Kaushik

    2016-12-01

    Despite significant advances in recent times, the investigation of discovering a perfect biomaterial is perennial. In this backdrop, blending of natural and synthetic polymers is gaining popularity since it is the easiest way to complement the drawbacks and attain a superlative material. Based on this, the objective of this study was to synthesize a novel polyester, poly(galactitol sebacate), and subsequently blend this polymer with one of the three natural polymers such as alginate, chitosan or ethyl cellulose. FT-IR showed the presence of both the polymers in the blends. 1 H NMR confirmed the chemical structure of the synthesized poly (galactitol sebacate). Thermal characterization was performed by DSC revealing that the polymers were amorphous in nature and the glass transition temperatures increased with the increase in ratio of the natural polymers in the blends. SEM imaging showed that the blends were predominantly homogeneous. Contact angle measurements demonstrated that the blending imparted the hydrophilic nature into poly (galactitol sebacate) when blending with alginate or chitosan and hydrophobic when blending with ethyl cellulose. In vitro hydrolytic degradation studies and dye release studies indicated that the polymers became more hydrophilic in alginate and chitosan blends and thus accelerated the degradation and release process. The reverse trend was observed in the case of ethyl cellulose blends. Modeling elucidated that the degradation and dye release followed first order kinetics and Higuchi kinetics, respectively. In vitro cell studies confirmed the cytocompatible nature of the blends. It can be proposed that the chosen natural polymers for blending showed wide variations in hydrophilicity resulting in tailored degradation, release and cytocompatibility properties and thus are promising candidates for use in drug delivery and tissue engineering. Copyright © 2016 Elsevier B.V. All rights reserved.

  19. Preparation and Characterization of Azadirachtin Alginate-Biosorbent Based Formulations: Water Release Kinetics and Photodegradation Study.

    Science.gov (United States)

    Flores-Céspedes, Francisco; Martínez-Domínguez, Gerardo P; Villafranca-Sánchez, Matilde; Fernández-Pérez, Manuel

    2015-09-30

    The botanical insecticide azadirachtin was incorporated in alginate-based granules to obtain controlled release formulations (CRFs). The basic formulation [sodium alginate (1.47%) - azadirachtin (0.28%) - water] was modified by the addition of biosorbents, obtaining homogeneous hybrid hydrogels with high azadirachtin entrapment efficiency. The effect on azadirachtin release rate caused by the incorporation of biosorbents such as lignin, humic acid, and olive pomace in alginate formulation was studied by immersion of the granules in water under static conditions. The addition of the biosorbents to the basic alginate formulation reduces the rate of release because the lignin-based formulation produces a slower release. Photodegradation experiments showed the potential of the prepared formulations in protecting azadirachtin against simulated sunlight, thus improving its stability. The results showed that formulation prepared with lignin provided extended protection. Therefore, this study provides a new procedure to encapsulate the botanical insecticide azadirachtin, improving its delivery and photostability.

  20. Porphyroblast crystallization kinetics: the role of the nutrient production rate

    DEFF Research Database (Denmark)

    Schwarz, Jens-Oliver; Engi, Martin; Berger, Alfons

    2011-01-01

    The mechanisms that govern porphyroblast crystallization are investigated by comparing quantitative textural data with predictions from different crystallization models. Such numerical models use kinetic formulations of the main crystallization mechanism to predict textural characteristics, such ...

  1. Study of growth kinetic and modeling of ethanol production by ...

    African Journals Online (AJOL)

    ... coefficient (0.96299). Based on Leudking-Piret model, it could be concluded that ethanol batch fermentation is a non-growth associated process. Key words: Kinetic parameters, simulation, cell growth, ethanol, Saccharomyces cerevisiae.

  2. Drug Release Kinetics and Front Movement in Matrix Tablets Containing Diltiazem or Metoprolol/λ-Carrageenan Complexes

    Directory of Open Access Journals (Sweden)

    Ruggero Bettini

    2014-01-01

    Full Text Available In this work we investigated the moving boundaries and the associated drug release kinetics in matrix tablets prepared with two complexes between λ-carrageenan and two soluble model drugs, namely, diltiazem HCl and metoprolol tartrate aiming at clarifying the role played by drug/polymer interaction on the water uptake, swelling, drug dissolution, and drug release performance of the matrix. The two studied complexes released the drug with different mechanism indicating two different drug/polymer interaction strengths. The comparison between the drug release behaviour of the complexes and the relevant physical mixtures indicates that diltiazem gave rise to a less soluble and more stable complex with carrageenan than metoprolol. The less stable metoprolol complex afforded an erodible matrix, whereas the stronger interaction between diltiazem and carrageenan resulted in a poorly soluble, slowly dissolving matrix. It was concluded that the different stability of the studied complexes affords two distinct drug delivery systems: in the case of MTP, the dissociation of the complex, as a consequence of the interaction with water, affords a classical soluble matrix type delivery system; in the case of DTZ, the dissolving/diffusing species is the complex itself because of the very strong interaction between the drug and the polymer.

  3. Kinetic, spectroscopic and chemical modification study of iron release from transferrin; iron(III) complexation to adenosine triphosphate

    International Nuclear Information System (INIS)

    Thompson, C.P.

    1985-01-01

    Amino acids other than those that serve as ligands have been found to influence the chemical properties of transferrin iron. The catalytic ability of pyrophosphate to mediate transferrin iron release to a terminal acceptor is largely quenched by modification non-liganded histine groups on the protein. The first order rate constants of iron release for several partially histidine modified protein samples were measured. A statistical method was employed to establish that one non-liganded histidine per metal binding domain was responsible for the reduction in rate constant. These results imply that the iron mediated chelator, pyrophosphate, binds directly to a histidine residue on the protein during the iron release process. EPR spectroscopic results are consistent with this interpretation. Kinetic and amino acid sequence studies of ovotransferrin and lactoferrin, in addition to human serum transferrin, have allowed the tentative assignment of His-207 in the N-terminal domain and His-535 in the C-terminal domain as the groups responsible for the reduction in rate of iron release. The above concepts have been extended to lysine modified transferrin. Complexation of iron(II) to adenosine triphosphate (ATP) was also studied to gain insight into the nature of iron-ATP species present at physiological pH. 31 P NMR spectra are observed when ATP is presented in large excess

  4. Second Order Kinetic Modeling of Headspace Solid Phase Microextraction of Flavors Released from Selected Food Model Systems

    Directory of Open Access Journals (Sweden)

    Jiyuan Zhang

    2014-09-01

    Full Text Available The application of headspace-solid phase microextraction (HS-SPME has been widely used in various fields as a simple and versatile method, yet challenging in quantification. In order to improve the reproducibility in quantification, a mathematical model with its root in psychological modeling and chemical reactor modeling was developed, describing the kinetic behavior of aroma active compounds extracted by SPME from two different food model systems, i.e., a semi-solid food and a liquid food. The model accounted for both adsorption and release of the analytes from SPME fiber, which occurred simultaneously but were counter-directed. The model had four parameters and their estimated values were found to be more reproducible than the direct measurement of the compounds themselves by instrumental analysis. With the relative standard deviations (RSD of each parameter less than 5% and root mean square error (RMSE less than 0.15, the model was proved to be a robust one in estimating the release of a wide range of low molecular weight acetates at three environmental temperatures i.e., 30, 40 and 60 °C. More insights of SPME behavior regarding the small molecule analytes were also obtained through the kinetic parameters and the model itself.

  5. Time extrapolation of radiolytic degradation product kinetics: the case of polyurethane; Extrapolation dans le temps des cinetiques de production des produits de degradation radiolytique: application a un polyurethane

    Energy Technology Data Exchange (ETDEWEB)

    Dannoux, A

    2007-02-15

    The prediction of the environmental impact of organic materials in nuclear waste geological storage needs knowledge of radiolytic degradation mechanisms and kinetics in aerobic and anaerobic conditions. In this framework, the effect of high doses (> MGy) and the variation of dose rate have to be considered. The material studied is a polyurethane composed of polyether soft segment and aromatic hard segments. Mechanisms were built on the analysis of material submitted to irradiations of simulation (high energy electrons and gamma radiation) by FTIR spectroscopy and gaseous and liquid degradation products by gas mass spectrometry and size exclusion chromatography. The electron paramagnetic resonance study of radical process and the determination of oxygen consumption and gas formation radiolytic yields allowed us to acquire kinetic data and to estimate dose rate and high doses effects. The polyurethane radio-oxidation mainly concerns soft segments and induced cross-linkings and production by scissions of oxidised compounds (esters, alcohols, carboxylic acids). The kinetic of radical termination is rapid and the dose rate effect is limited. After 10 MGy, branching and scission reactions are in equilibrium and low molecular weight products accumulate. At last, the degradation products release in water is influenced by the oxidation rate and the temperature. After 10 MGy, the soluble fraction is stabilised at 25%. The water soluble products identified by electro-spray ionisation mass spectrometry (alcohols, aldehydes, carboxylic acids) potentially formed complexes with radionuclides. (author)

  6. Improvement of succinate production by release of end-product inhibition in Corynebacterium glutamicum.

    Science.gov (United States)

    Chung, Soon-Chun; Park, Joon-Song; Yun, Jiae; Park, Jin Hwan

    2017-03-01

    Succinate is a renewable-based platform chemical that may be used to produce a wide range of chemicals including 1,4-butanediol, tetrahydrofurane, and γ-butyrolactone. However, industrial fermentation of organic acids is often subject to end-product inhibition, which significantly retards cell growth and limits metabolic activities and final productivity. In this study, we report the development of metabolically engineered Corynebacterium glutamicum for high production of succinate by release of end-product inhibition coupled with an increase of key metabolic flux. It was found that the rates of glucose consumption and succinate production were significantly reduced by extracellular succinate in an engineered strain, S003. To understand the mechanism underlying the inhibition by succinate, comparative transcriptome analysis was performed. Among the downregulated genes, overexpression of the NCgl0275 gene was found to suppress the inhibition of glucose consumption and succinate production, resulting in a 37.7% increase in succinate production up to 55.4g/L in fed-batch fermentation. Further improvement was achieved by increasing the metabolic flux from PEP to OAA. The final engineered strain was able to produce 152.2g/L succinate, the highest production reported to date, with a yield of 1.1g/g glucose under anaerobic condition. These results suggest that the release of end-product inhibition coupled with an increase in key metabolic flux is a promising strategy for enhancing production of succinate. Copyright © 2017. Published by Elsevier Inc.

  7. Safety barriers to prevent release of hydrocarbons during production of oil and gas

    OpenAIRE

    Sklet, Snorre; Hauge, Stein

    2004-01-01

    This report documents a set of scenarios related to release of hydrocarbons during production on oil and gas platforms. For each release scenario, initiating events, barrier functions aimed to prevent loss of containment, and barrier systems that realize these barrier functions are identified and described. Safety barriers to prevent release of hydrocarbons during production of oil and gas

  8. Release of mineral ions in dental plaque following acid production.

    Science.gov (United States)

    Tanaka, M; Margolis, H C

    1999-03-01

    The release of appreciable amounts of calcium, phosphate and fluoride found in whole plaque into the plaque-fluid phase, following bacterial acid production, can potentially reduce the driving force for tooth demineralization. However, limited information is available on this topic, particularly on the release of fluoride. This study sought to determine the change in calcium, phosphate and fluoride concentrations in plaque fluid after sucrose exposure. 48 h overnight-fasted supragingival plaque samples were collected from all tooth surfaces (with the exception of the lower lingual anterior teeth) of one half of an individual mouth, following a 1 min water rinse. Plaque samples were then collected from the other half of the same mouth, following a 292 mM sucrose rinse. Plaque fluid was isolated by centrifugation and analysed for total calcium and phosphate (ion chromatography) and for free fluoride (ion-specific electrode). Samples were collected from seven individuals. Following sucrose exposure, plaque-fluid pH decreased significantly from 6.5+/- 0.3 to 5.4+/-0.2; calcium concentrations (mmol/l) also increased significantly (p Fluoride and phosphate concentrations in plaque fluid, however, did not increase significantly after sucrose exposure: mean concentrations (mmol/l) of fluoride after the water and sucrose rinses were 0.006+/-0.003 and 0.005+/-0.002, respectively, and mean phosphate concentrations (mmol/l) were 11.0+/-2.0 and 12.0+/-3.0, respectively. When results were expressed per wet plaque weight, phosphate concentrations were also found to increase significantly. The same trends were observed when additional plaque samples were treated in vitro with sucrose: fluoride-ion activity did not increase in plaque under in vivo-like conditions.

  9. Measuring and modelling in-vitro gas production kinetics to evaluate ruminal fermentation of feedstuffs

    NARCIS (Netherlands)

    Beuvink, J.M.W.

    1993-01-01

    In this thesis, the possibilities of kinetic gas production measurements for the evaluation of ruminant feedstuffs have been examined. Present in-vitro methods were mostly end- point methods. There was a need for a kinetic in-vitro method that described ruminal fermentation, due to new

  10. Application of Uncertainty and Sensitivity Analysis to a Kinetic Model for Enzymatic Biodiesel Production

    DEFF Research Database (Denmark)

    Price, Jason Anthony; Nordblad, Mathias; Woodley, John

    2014-01-01

    This paper demonstrates the added benefits of using uncertainty and sensitivity analysis in the kinetics of enzymatic biodiesel production. For this study, a kinetic model by Fedosov and co-workers is used. For the uncertainty analysis the Monte Carlo procedure was used to statistically quantify...

  11. Kinetics and mechanisms of metal retention/release in geochemical processes in soil. 1997 annual progress report

    International Nuclear Information System (INIS)

    Taylor, R.W.

    1997-01-01

    'Remediation of soils polluted with heavy metals is a major challenge facing the nation. This is especially so at many DOE facilities and other superfund sites. In many cases, speciation of the metals is inaccurate and difficult and the mechanisms by which the metals are retained/released in soils over long times are poorly understood. Consequently, the long-term fate of metals in soils cannot be precisely predicted and often, the remediation recommendations and techniques that are employed to clean up soils may be ineffective or unnecessary. Accordingly, the authors are proposing work to generate basic knowledge on the kinetics and mechanism(s) of heavy metal retention/release by soil mineral colloids as affected by inorganic anion. The nature of the interaction of Cd(II), Co(II), Cr(VI), Cu(II), Ni(II) and Pb(II) with pure soil minerals and extracted soil clays will be investigated. The colloids will be characterized in terms of surface area, surface charge and surface site density. They will be used to study the effect(s) of pH, phosphate rate, and temperature on metals retention/release. The experiments will involve using various kinetic and isothermic sorption equations as models to describe the data thus acquired. The spectroscopic methods will involve using extended x-ray absorption fine structure spectroscopy (EXAFS) and Fourier Transform Infrared Spectroscopy (FTIR). The data generated from the proposed study will assist in designing better remediation strategies to effectively clean up toxic heavy metal contaminated soils at DOE facilities and other superfund sites.'

  12. Kinetic computer modeling of microwave surface-wave plasma production

    International Nuclear Information System (INIS)

    Ganachev, Ivan P.

    2004-01-01

    Kinetic computer plasma modeling occupies an intermediate position between the time consuming rigorous particle dynamic simulation and the fast but rather rough cold- or warm-plasma fluid models. The present paper reviews the kinetic modeling of microwave surface-wave discharges with accent on recent kinetic self-consistent models, where the external input parameters are reduced to the necessary minimum (frequency and intensity of the applied microwave field and pressure and geometry of the discharge vessel). The presentation is limited to low pressures, so that Boltzmann equation is solved in non-local approximation and collisional electron heating is neglected. The numerical results reproduce correctly the bi-Maxwellian electron energy distribution functions observed experimentally. (author)

  13. Release of indigenous gases from LWR fuel and the reaction kinetics with Zircaloy cladding

    International Nuclear Information System (INIS)

    Beyer, C.E.; Hann, C.R.

    1977-04-01

    The objective of this study was to evaluate the open literature data to estimate: the rate of gaseous impurity release from oxide fuel, the amount and composition of the gaseous impurities, and their subsequent rate of reaction with the fuel or Zircaloy

  14. Tritium release kinetics of Li{sub 2}O with radiation defects

    Energy Technology Data Exchange (ETDEWEB)

    Grishmanov, V; Tanaka, Satoru [Tokyo Univ. (Japan). Faculty of Engineering

    1998-03-01

    The study of an influence of radiation defects on tritium release behavior from polycrystalline Li{sub 2}O was performed by the in-pile and out-of-pile tritium release experiments. The samples were pre-irradiated by accelerated electrons to various absorbed doses up to 140 MGy and then exposed to the fluence of 10{sup 17} thermal neutrons/m{sup 2}. The radiation defects introduced by electron irradiation in Li{sub 2}O cause the retention of tritium. The linear temperature increase of the electron-irradiated samples disclosed two tritium release peaks: first starts at {approx}600 K with the maximum at {approx}800 K and second appears at {approx}950 K with the maximum at {approx}1200 K. It is thought that the tritium release at high temperatures (> 950 K) is due to the thermal decomposition of LiT. In order to further investigated the formation of lithium hydrides, the diffuse-reflectance Fourier transform infrared (FTIR) absorption spectroscopy was applied. The Li{sub 2}O powder was irradiated by electron accelerator under D{sub 2} containing atmosphere (N{sub 2} + 10% D{sub 2}). An absorption band specific to the Li{sub 2}O was observed at 668 cm{sup -1} and attributed to the Li-D stretching vibration. (author)

  15. Formulation and In Vitro Release Kinetics of Mucoadhesive Blend Gels Containing Matrine for Buccal Administration.

    Science.gov (United States)

    Chen, Xiaojin; Yan, Jun; Yu, Shuying; Wang, Pingping

    2018-01-01

    Enterovirus 71 (EV71) is a pathogenic factor of severe hand, foot, and mouth disease (HFMD). No vaccine or specific treatment is currently available for EV71 infection. Hence, we developed a buccal mucoadhesive gel containing matrine to protect against HFMD. Mucoadhesive gels were prepared by Carbopol 974P and were combined with Carbopol 971P, sodium carboxymethyl cellulose (CMC-Na), or hydroxypropylmethy cellulose (HPMC K100M). The formulations were characterized in terms of tensile testing and continuous flow techniques for mucoadhesion. The rheological studies and in vitro drug release characteristics were also investigated. The results showed that combinations of two polymers significantly improved mucoadhesion, especially Carbopol 974P blended with HPMC. Carbopol 974P to HPMC blend ratios of 1:1 and 2:1 induced better mucoadhesion in the tensile test and continuous flow method, respectively. The most sustained release was obtained at a Carbopol 974P to HPMC ratio of 2.5:1. A predominantly non-Fickian diffusion release mechanism was obtained. The gel containing 2.5% Carbopol 974P combined with 1% HPMC showed good mucoadhesion properties and sustained drug release.

  16. Release Kinetics and Antibacterial Efficacy of Microporous β-TCP Coatings

    Directory of Open Access Journals (Sweden)

    Michael Seidenstuecker

    2013-01-01

    Full Text Available Purpose. The aim of this study was to impregnate microporous β-TCP scaffolds with different antibiotic solutions and to determine their release behavior. Materials and Methods. We impregnated a β-TCP scaffold with antibiotics by using three methods: drop, dip, and stream coating with 120 mg/mL of antibiotic solution. After drying for 72 h at 37°C, 2 mL of distilled water was added to the antibiotic-coated plugs and incubated at 37°C. After defined time points (1, 2, 3, 6, 9, and 14 days, the liquid was completely replaced. The extracted liquid was analyzed by capillary zone electrophoresis and the Kirby Bauer disc diffusion test. For statistical analysis, we calculated a mean and standard deviation and carried out an analysis of variance using ANOVA. Results. The VAN and CLI release from the β-TCP scaffolds was rapid, occurring within 24 h with 89 ± 0.8% VAN and 90.4 ± 1.5% CLI regardless of the type of insulation. After six days, the VAN and CLI were completely released. All samples taken at later time points had a VAN or CLI concentration below the detection limit of 4 µg/mL. The released amounts of VAN and CLI within the first three days revealed antimicrobial activity.

  17. Behavior of fission products released from severely damaged fuel during the PBF severe fuel damage tests

    International Nuclear Information System (INIS)

    Osetek, D.J.; Cronenberg, A.W.; Hagrman, D.L.; Broughton, J.M.; Rest, J.

    1984-01-01

    The results of fission product release behavior during the first two Power Burst Facility Severe Fuel Damage tests are presented. Measured fission product release is compared with calculated release using temperature dependent release rate correlations and FASTGRASS analysis. The test results indicate that release from fuel of the high volatility fission products (Xe, Kr, I, Cs, and Te) is strongly influenced by parameters other than fuel temperature; namely fuel/fission product morphology, fuel and cladding oxidation state, extent of fuel liquefaction, and quench induced fuel shattering. Fission product transport from the test fuel through the sample system was strongly influenced by chemical effects. Holdup of I and Cs was affected by fission product chemistry, and transport time while Te release was primarily influenced by the extent of zircaloy oxidation. Analysis demonstrates that such integral test data can be used to confirm physical, chemical, and mechanistic models of fission product behavior for severe accident conditions

  18. Kinetics of Intracellular, Extracellular and Production of Pro ...

    African Journals Online (AJOL)

    Keywords: Pro-inflammatory cytokine, Tumor necrosis factor-α, Interleukin-1α, Interleukin-1β,. Interleukin-6, Interleukin-8. Tropical Journal of ... retains neutrophils at sites of inflammation [6]. Many studies on the kinetics of cytokine ..... Lijnen P, Saavedra A, Petrov P. In vitro proliferative response of human peripheral blood ...

  19. RSAC-6, Gamma doses, inhalation and ingestion doses, fission products inventory after fission products release

    International Nuclear Information System (INIS)

    Wenzel, Douglas R.; Schrader, Brad J.

    2007-01-01

    1 - Description of program or function: RSAC-6 is the latest version of the program RSAC (Radiological Safety Analysis Computer Program). It calculates the consequences of a release of radionuclides to the atmosphere. Using a personal computer, a user can generate a fission product inventory; decay and in-grow the inventory during transport through processes, facilities, and the environment; model the downwind dispersion of the activity; and calculate doses to downwind individuals. Internal dose from the inhalation and ingestion pathways is calculated. External dose from ground surface and plume gamma pathways is calculated. New and exciting updates to the program include the ability to evaluate a release to an enclosed room, resuspension of deposited activity and evaluation of a release up to 1 meter from the release point. Enhanced tools are included for dry deposition, building wake, occupancy factors, respirable fraction, AMAD adjustment, updated and enhanced radionuclide inventory and inclusion of the dose-conversion factors from FOR 11 and 12. 2 - Methods: RSAC6 calculates meteorological dispersion in the atmosphere using Gaussian plume diffusion for Pasquill-Gifford, Hilmeier-Gifford and Markee models. A unique capability is the ability to model Class F fumigation conditions, the meteorological condition that causes the highest ground level concentrations from an elevated release. Doses may be calculated for various pathways including inhalation, ingestion, ground surface, air immersion, water immersion pathways. Dose calculations may be made for either acute or chronic releases. Internal doses (inhalation and ingestion) are calculated using the ICRP-30 model with dose conversion factors from FOR 11. External factors are calculated using FOR 12. 3 - Unusual Features: RSAC6 calculates complete progeny in-growth and decay during all accident phases. The calculation of fission product inventories in particularly useful in the analysis of accidents where the

  20. Fuel behavior and fission product release under HTGR accident conditions

    International Nuclear Information System (INIS)

    Fukuda, K.; Hayashi, K.; Shiba, K.

    1990-01-01

    In early 1989 a final decision was made over construction of a 30 MWth HTGR called the High Temperature Engineering Test Reactor, HTTR, in Japan in order to utilize it for high temperature gas engineering tests and various nuclear material tests. The HTTR fuel is a pin-in-block type fuel element which is composed of a hexagonal graphite block with dimension of 580 mm in length and 360 mm in face-to-face distance and about 30 of the fuel rods inserted into the coolant channels drilled in the block. The TRISO coated fuel particles for HTTR are incorporated with graphite powder and phenol resin into the fuel compacts, 19 of which are encased into a graphite sleeve as a fuel rod. It is necessary for the HTTR licensing to prove the fuel stability under predicted accidents related to the high temperature events. Therefore, the release of the fission products and the fuel failure have been investigated in the irradiation---and the heating experiments simulating these conditions at JAERI. This report describes the HTTR fuel behavior at extreme temperature, made clear in these experiments

  1. Time-dependent histamine release from stored human blood products

    DEFF Research Database (Denmark)

    Nielsen, Hans Jørgen; Edvardsen, L; Vangsgaard, K

    1996-01-01

    storage. Whole blood (six units), plasma-reduced whole blood (six units), and plasma- and buffy coat-reduced (saline-adenine-glucose-mannitol) (SAGM) blood (six units) from unpaid healthy donors were stored in the blood bank for 35 days at 4 degrees C. Plasma histamine and total cell-bound histamine......Perioperative transfusion of whole blood has been shown to amplify trauma-induced immunosuppression, which could be attenuated by perioperative administration of histamine2 receptor antagonists. Supernatants from different blood products were, therefore, analysed for histamine content during.......0 (range 176.0-910.0) nmol/l in whole blood and 475.0 (range 360.0-1560.0) nmol/l in plasma-reduced whole blood, while it was undetectable in SAGM blood. Spontaneous histamine release increased in a time-dependent manner from a median of 6.7 (range 2.2-17.4) nmol/l at the time of storage to 175.0 (range 33...

  2. Fuel behaviour and fission product release under realistic hydrogen conditions comparisons between HEVA 06 test results and Vulcain computations

    International Nuclear Information System (INIS)

    Dumas, J.M.; Lhiaubet, G.

    1989-07-01

    The HEVA 06 test was designed to simulate the conditions existing at the time when fission products are released from irradiated fuel under hydrogen conditions occurring in a PWR core at low pressure. The test conditions were defined from results provided by the core degradation module of the ESCADRE system (1): VULCAIN. This computer code has been recently used to analyse the early core degradation of a 900 MWe PWR in the AF accident sequence (as defined in WASH - 1400, USNRC - 1975). In this scenario, the core would begin to uncover about one day after scram with the system pressure at about 0.4 MPa. The fission product release starts 70 minutes after core dewatering. The F.P. are transferred to the core outlet in an increasingly hydrogen-rich steam atmosphere. The carrier gas is nearly pure hydrogen in the time period 100 - 130 minutes after core uncovering. A large release of F.P. is predicted in the upper part of the core when the steam starvation occurs. At that time, two thirds of the cladding have been oxidised on an average. Before each HEVA test a fuel sample with a burn-up of 36 GWd/tU is reirradiated in order to observe the release of short-lived fission products. A pre-oxidation was primarely conducted in the HEVA 06 test at a temperature of 1300 0 C and controlled to reach a 2/3 cladding oxidation state. Then the steam was progressively replaced by hydrogen and a heat-up rate of 1.5 0 C/s was induced to reach a temperature of 2100 0 C. The fuel was maintained at this temperature for half an hour in hydrogen. The volatile F.P. release kinetics were observed by on-line gamma spectrometry. Pre test calculations of F.P. release kinetics performed with the EMIS module based on the CORSOR models (3) are compared with the test results. Measured releases of cesium and iodine are really lower than those predicted. Axial and radial F.P. distributions in the fuel pellets are available from gamma tomography measurements performed after the test. Tellurium seems

  3. Research Article. Kinetics and Mechanism of Drug Release from Loratadine Orodispersible Tablets Developed without Lactose

    Directory of Open Access Journals (Sweden)

    Ciurba Adriana

    2017-03-01

    Full Text Available Objective: The aim of this study is to develop lactose-free orodispersible tablets with loratadine for patients with lactose intolerance. Materials and methods: Seven compositions (F1-F7 of 10 mg loratadine were prepared in form of orally disintegrating tablets, by direct compression, using croscarmellose sodium and pre-gelatinized starch in various concentrations as superdisintegrants, diluted with microcrystalline cellulose and combined with mannitol and maltodextrin as binder agents. The tablets had been studied in terms of their pharmacotechnical characteristics, by determining: the weight uniformity of the tablets, their friability, breaking strength and disintegration time, drug content and the dissolution profile of loratadine. The statistical analyses were performed with GraphPad Prism Software Inc. As dependent variables, both the hardness of the tablets and their disintegration ability differ between batches due to their compositional differences (as independent variables. DDSolver were used for modeling the kinetic of the dissolution processes by fitting the dissolution profiles with time-dependent equations (Zero-order, First-order, Higuchi, Korsmeyer-Peppas, Peppas-Sahlin. Results: All proposed formulas shows rapid disintegration, in less than 15 seconds, and the dissolution loratadine spans a period of about 10 minutes. Akaike index as well as R2 adjusted parameter have demonstrated that the studied dissolution profiles are the best fitted by Zero-order kinetic. Conclusion: In conclusion, association of croscarmellose sodium (7.5% with pre-gelatinized starch (6% as superdisintegrants and mannitol as the binder agent (35%, positively influences the dissolution properties of loratadine from orally fast dispersible tablets.

  4. Kinetic rate of iron release during artificial CO{sub 2} injection in a shallow aquifer: preliminary results

    Energy Technology Data Exchange (ETDEWEB)

    Rillard, J. [Earth Sciences Department UMR CNRS 5276 University of Lyon 1, Villeurbanne (France); INERIS French National Institut of Environmental and Industrial Risk Survey, Underground Risk Division,, Verneuil en Hallate (France); Gombert, P.; Toulhoat, P. [INERIS French National Institut of Environmental and Industrial Risk Survey, Underground Risk Division,, Verneuil en Hallate (France); Zuddas, P. [Earth Sciences Department UMR CNRS 5276 University of Lyon 1, Villeurbanne (France); University Pierre and Marie Curie Paris-Sorbonne, ISTEP, Paris (France)

    2013-07-01

    We performed an injection of CO{sub 2}-saturated water in a shallow aquifer following a 'push-pull' test protocol. A specific protocol was designed to measure in situ fluid pH and redox potential with careful sampling. We found increases of dissolved calcium, magnesium, alkalinity, iron and manganese, and other trace elements. Concentrations of Fe resulting from reactivity were estimated using measured concentrations of Fe corrected by a calculated fluid dynamics coefficient. Thermodynamic equilibrium calculations suggested that ferri-hydrite Fe(OH){sub 3} dissolution is the main source of iron release. The kinetic rate of Fe(OH){sub 3} dissolution estimated by a surface protonation model indicates that the reaction order is two. Since laboratory experimental results show a reaction order of zero, we propose that the mechanism of ferri-hydrite dissolution proceeds by a more complex mechanism under natural conditions. (authors)

  5. Spray Drying Processing: granules production and drying kinetics of droplets

    International Nuclear Information System (INIS)

    Mondragon, R.; Julia, J. E.; Barba, A.; Jarque, J. C.

    2013-01-01

    Spray drying is a unit operation very common in many industrial processes. For each particular application, the resulting granulated material must possess determined properties that depend on the conditions in which the spray drying processing has been carried out, and whose dependence must be known in order to optimize the quality of the material obtained. The large number of variables that influence on the processes of matter and energy transfer and on the formation of granular material has required a detailed analysis of the drying process. Over the years there have been many studies on the spray drying processing of all kind of materials and the influence of process variables on the drying kinetics of the granulated material properties obtained. This article lists the most important works published for both the spray drying processing and the drying of individual droplets, as well as studies aimed at modeling the drying kinetics of drops. (Author)

  6. Synthesis, characterization, release kinetics and toxicity profile of drug-loaded starch nanoparticles.

    Science.gov (United States)

    El-Naggar, Mehrez E; El-Rafie, M H; El-sheikh, M A; El-Feky, Gina S; Hebeish, A

    2015-11-01

    The current research work focuses on the medical application of the cost-effective cross-linked starch nanoparticles, for the transdermal delivery using Diclofenac sodium (DS) as a model drug. The prepared DS-cross-linked starch nanoparticles were synthesized using nanoprecipitation technique at different concentrations of sodium tripolyphosphate (STPP) in the presence of Tween 80 as a surfactant. The resultant cross-linked starch nanoparticles loaded with DS were characterized using world-class facilities such as TEM, DLS, FT-IR, XRD, and DSc. The efficiency of DS loading was also evaluated via entrapment efficiency as well as in vitro release and histopathological study on rat skin. The optimum nanoparticles formulation selected by the JMP(®) software was the formula that composed of 5% maize starch, 57.7mg DS and 0.5% STPP and 0.4% Tween 80, with particle diameter of about 21.04nm, polydispersity index of 0.2 and zeta potential of -35.3mV. It is also worth noting that this selected formula shows an average entrapment efficiency of 95.01 and sustained DS release up to 6h. The histophathological studies using the best formula on rat skin advocate the use of designed transdermal DS loaded cross-linked starch nanoparticles as it is safe and non-irritant to rat skin. The overall results indicate that, the starch nanoparticles could be considered as a good carrier for DS drug regarding the enhancement in its controlled release and successful permeation, thus, offering a promising nanoparticulate system for the transdermal delivery non-steroidal anti-inflammatory drug (NSAID). Copyright © 2015 Elsevier B.V. All rights reserved.

  7. The Plinius/Colima CA-U3 test on fission-product aerosol release over a VVER-type corium pool

    International Nuclear Information System (INIS)

    Journeau, Ch.; Piluso, P.; Correggio, P.; Godin-Jacqmin, L.

    2007-01-01

    In a hypothetical case of severe accident in a PWR type VVER-440, a complex corium pool could be formed and fission products could be released. In order to study aerosols release in terms of mechanisms, kinetics, nature or quantity, and to better precise the source term of VVER-440, a series of experiments have been performed in the Colima facility and the test Colima CA-U3 has been successfully performed thanks to technological modifications to melt a prototypical corium at 2760 C degrees. Specific instrumentation has allowed us to follow the evolution of the corium melt and the release, transport and deposition of the fission products. The main conclusions are: -) there is a large release of Cr, Te, Sr, Pr and Rh (>95%w), -) there is a significant release of Fe (50%w), -) there is a small release of Ba, Ce, La, Nb, Nd and Y (<90%w), -) there is a very small release of U in proportion (<5%w) but it is one of the major released species in mass, and -) there is no release of Zr. The Colima experimental results are consistent with previous experiments on irradiated fuels except for Ba, Fe and U releases. (A.C.)

  8. Background and derivation of ANS-5.4 standard fission product release model. Technical report

    International Nuclear Information System (INIS)

    1982-01-01

    ANS Working Group 5.4 was established in 1974 to examine fission product releases from UO2 fuel. The scope of ANS-5.4 was narrowly defined to include the following: (1) Review available experimental data on release of volatile fission products from UO2 and mixed-oxide fuel; (2) Survey existing analytical models currently being applied to lightwater reactors; and (3) Develop a standard analytical model for volatile fission product release to the fuel rod void space. Place emphasis on obtaining a model for radioactive fission product releases to be used in assessing radiological consequences of postulated accidents

  9. Radiation Damage and Fission Product Release in Zirconium Nitride

    Energy Technology Data Exchange (ETDEWEB)

    Egeland, Gerald W. [New Mexico Inst. of Mining and Technology, Socorro, NM (United States)

    2005-08-29

    Zirconium nitride is a material of interest to the AFCI program due to some of its particular properties, such as its high melting point, strength and thermal conductivity. It is to be used as an inert matrix or diluent with a nuclear fuel based on transuranics. As such, it must sustain not only high temperatures, but also continuous irradiation from fission and decay products. This study addresses the issues of irradiation damage and fission product retention in zirconium nitride through an assessment of defects that are produced, how they react, and how predictions can be made as to the overall lifespan of the complete nuclear fuel package. Ion irradiation experiments are a standard method for producing radiation damage to a surface for observation. Cryogenic irradiations are performed to produce the maximum accumulation of defects, while elevated temperature irradiations may be used to allow defects to migrate and react to form clusters and loops. Cross-sectional transmission electron microscopy and grazing-incidence x-ray diffractometry were used in evaluating the effects that irradiation has on the crystal structure and microstructure of the material. Other techniques were employed to evaluate physical effects, such as nanoindentation and helium release measurements. Results of the irradiations showed that, at cryogenic temperatures, ZrN withstood over 200 displacements per atom without amorphization. No significant change to the lattice or microstructure was observed. At elevated temperatures, the large amount of damage showed mobility, but did not anneal significantly. Defect clustering was possibly observed, yet the size was too small to evaluate, and bubble formation was not observed. Defects, specifically nitrogen vacancies, affect the mechanical behavior of ZrN dramatically. Current and previous work on dislocations shows a distinct change in slip plane, which is evidence of the bonding characteristics. The stacking-fault energy changes dramatically with

  10. Release kinetics of N-terminal pro-B-type natriuretic peptide in a clinical model of acute myocardial infarction.

    Science.gov (United States)

    Liebetrau, Christoph; Gaede, Luise; Dörr, Oliver; Troidl, Christian; Voss, Sandra; Hoffmann, Jedrzej; Paszko, Agata; Weber, Michael; Rolf, Andreas; Hamm, Christian; Nef, Holger; Möllmann, Helge

    2014-02-15

    N-terminal segment of B-type natriuretic peptide prohormone (NT-proBNP) is elevated in patients with acute myocardial infarction (AMI) thus providing both diagnostic information and prognostic information. The aim of the present study was to determine the time course of NT-proBNP release in patients undergoing transcoronary ablation of septal hypertrophy (TASH) a procedure mimicking AMI. We analyzed the release kinetics of NT-proBNP in 18 consecutive patients with hypertrophic obstructive cardiomyopathy undergoing TASH. Serum samples were collected prior to and at 15, 30, 45, 60, 75, 90, and 105 min, and 2, 4, 8, and 24h after TASH. NT-proBNP concentrations showed a continuous increase during the first 75 min with a significant percent change compared to baseline value already 15 min after TASH (105.6% [IQR 102.2-112.7]; Pvalue until the 8th h after initiation of myocardial infarction. NT-proBNP concentration increases immediately after induction of myocardial infarction proving early evidence of myocardial injury despite the decrease of the left ventricular wall stress due to the TASH related reduction of the left ventricular outflow gradient. Copyright © 2013 Elsevier B.V. All rights reserved.

  11. Kinetics of potassium release in sweet potato cropped soils: a case study in the highlands of Papua New Guinea

    Science.gov (United States)

    Rajashekhar Rao, B. K.

    2015-02-01

    The present study attempts to employ potassium (K) release parameters to identify soil-quality degradation due to changed land use patterns in sweet potato (Ipomoea batatas (L.) Lam) farms of the highlands of Papua New Guinea. Rapid population increase in the region increased pressure on the land to intensify subsistence production mainly by reducing fallow periods. Such continuous cropping practice coupled with lack of K fertilization practices could lead to a rapid loss of soil fertility and soil-resource degradation. The study aims to evaluate the effects of crop intensification on the K-release pattern and identify soil groups vulnerable to K depletion. Soils with widely differing exchangeable and non-exchangeable K contents were sequentially extracted for periods between 1 and 569 h in 0.01 M CaCl2, and K-release data were fitted to four mathematical models: first order, power, parabolic diffusion and Elovich equations. Results showed two distinct parts in the K-release curves, and 58-80% of total K was released to solution phase within 76 h (first five extractions) with 20-42% K released in the later parts (after 76 h). Soils from older farms that were subjected to intensive and prolonged land use showed significantly (P farms recently brought to cultivation (new farms). Among the four equations, first-order and power equations best described the K-release pattern; the constant b, an index of K-release rates, ranged from 0.005 to 0.008 mg kg-1 h-1 in the first-order model and was between 0.14 and 0.83 mg kg-1 h-1 in the power model for the soils. In the non-volcanic soils, model constant b values were significantly (P < 0.05) higher than the volcanic soils, thus indicating the vulnerability of volcanic soils to K deficiency. The volcanic soils cropped for several crop cycles need immediate management interventions either through improved fallow management or through mineral fertilizers plus animal manures to sustain productivity.

  12. Release kinetics of platelet-derived and plasma-derived growth factors from autologous plasma rich in growth factors.

    Science.gov (United States)

    Anitua, Eduardo; Zalduendo, Mari Mar; Alkhraisat, Mohammad Hamdan; Orive, Gorka

    2013-10-01

    Many studies have evaluated the biological effects of platelet rich plasma reporting the final outcomes on cell and tissues. However, few studies have dealt with the kinetics of growth factor delivery by plasma rich in growth factors. Venous blood was obtained from three healthy volunteers and processed with PRGF-Endoret technology to prepare autologous plasma rich in growth factors. The gel-like fibrin scaffolds were then incubated in triplicate, in a cell culture medium to monitor the release of PDGF-AB, VEGF, HGF and IGF-I during 8 days of incubation. A leukocyte-platelet rich plasma was prepared employing the same technology and the concentrations of growth factors and interleukin-1β were determined after 24h of incubation. After each period, the medium was collected, fibrin clot was destroyed and the supernatants were stored at -80°C until analysis. The growth factor delivery is diffusion controlled with a rapid initial release by 30% of the bioactive content after 1h of incubation and a steady state release when almost 70% of the growth factor content has been delivered. Autologous fibrin matrix retained almost 30% of the amount of the growth factors after 8 days of incubation. The addition of leukocytes to the formula of platelet rich plasma did not increase the concentration of the growth factors, while it drastically increased the presence of pro-inflammatory IL-1β. Further studies employing an in vitro inflammatory model would be interesting to study the difference in growth factors and pro-inflammatory cytokines between leukocyte-free and leukocyte-rich platelet rich plasma. Copyright © 2013 Elsevier GmbH. All rights reserved.

  13. Kinetic and theoretical studies of novel biodegradable thermo-sensitive xerogels based on PEG/PVP/silica for sustained release of enrofloxacin

    Science.gov (United States)

    Ebadi, Azra; Rafati, Amir Abbas; Bavafa, Sadeghali; Mohammadi, Masoumah

    2017-12-01

    This study involves the synthesis of a new silica-based colloidal hybrid system. In this new hybrid system, poly (ethylene glycol) (PEG) and thermo-sensitive amphiphilic biocompatible poly (vinyl pyrrolidone) (PVP) were used to create suitable storage for hydrophobic drugs. The possibility of using variable PVP/PEG molar ratios to modulate drug release rate from silica nanoparticles was a primary goal of the current research. In addition, an investigation of the drug release kinetic was conducted. To achieve this, silica nanoparticles were synthesized in poly (ethylene glycol) (PEG) and poly (vinyl pyrrolidone) (PVP) solution incorporated with enrofloxacin (EFX) (as a model hydrophobic drug), using a simple synthetic strategy of hybrid materials which avoided waste and multi-step processes. The impacts of PVP/PEG molar ratios, temperature, and pH of the release medium on release kinetic were investigated. The physicochemical properties of the drug-loaded composites were studied by Fourier transform infrared (FT-IR) spectra, scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). In vitro drug release studies demonstrated that the drug release rate, which was evaluated by analyzing the experimental data with seven kinetic models in a primarily non-Fickian diffusion-controlled process, aligned well with both Ritger-Peppas and Sahlin-Peppas equations.

  14. Evaluation of methane production features and kinetics of ...

    African Journals Online (AJOL)

    zino

    2015-06-03

    Jun 3, 2015 ... as agricultural fertilizer. In recent years, the conversion of ... few studies investigated the biogas production rate. In the ... evaluate biogas production rate using obtained .... The parameters obtained in the optimization process.

  15. Release of fission products from irradiated aluminide fuel at high temperature

    International Nuclear Information System (INIS)

    Shibata, Toshikazu; Kanda, Keiji; Mishima, Kaichiro; Tamai, Tadaharu; Hayashi, Masatoshi; Snelgrove, James L.; Stahl, David; Matos, James E.; Travelli, Armando; Case, F. Neil; Posey, John C.

    1983-01-01

    Irradiated uranium aluminide fuel plates of 40% U-235 enrichment were heated for the determination of fission products released under flowing helium gas at temperatures up to and higher than the melting point of fuel cladding material. The release of fission products from the fuel plate at temperature below 500 deg. C was found negligible. The first rapid release of fission products was observed with the occurrence of blistering at 561±1 deg. C on the plates. The next release at 585. C might be caused by melting of the cladding material of 6061-Al alloy. The last release of fission product gases was occurred at the eutectic temperature of 640 deg. C of U-Al x . The released material was mostly xenon, but small amounts of iodine and cesium were observed. (author)

  16. Release of fission products from irradiated aluminide fuel at high temperature

    International Nuclear Information System (INIS)

    Shibata, T.; Kanda, K.; Mishima, K.

    1982-01-01

    Irradiated uranium aluminide fuel plates of 40% U-235 enrichment were heated for the determination of fission products released under flowing helium gas at temperatures up to and higher than the melting point of fuel-cladding material. The release of fission products from the fuel plate at temperature below 500 0 C was found negligible. The firist rapid release of fission products was observed with the occurrence of blistering at 561 +- 1 0 C on the plates. The next release at 585 0 C might be caused by melting of the cladding material of 6061-Al alloy. The last release of fission product gases was occurred at the eutectic temperature of 640 0 C of U-Al/sub x/. The released material was mostly xenon, but small amounts of iodine and cesium were observed

  17. Kinetics and Mechanism of Metal Retention/Release in Geochemical Processes in Soil - Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Taylor, Robert W.

    2000-12-29

    Effective, remediation of soils contaminated with heavy metals requires a better understanding of the mechanisms by which the metals are retained/released in soils over a long period of time. Studies on reaction of Cr(VI) with iron-rich clays indicated that structural iron (II) in these surfaces is capable of reducing chromate to chromium (III). We found that iron (II) either found naturally or produced by treatment of clay with sodium dithionite, effectively reduced Cr (VI) to Cr (III). Thus, in situ remediation of chromium combines reduction of Cr (VI) to Cr (III) and immobilization of chromium on mineral surfaces. During this study, lead sorption on a kaolin surface was found to be a rapid and a pH dependant process in which lead sorption significantly increased with the amount of phosphate on the clay surface. This study verifies that methylmercury cation remains intact when it binds to humic acids, forming a monodentate complex with some sub-population of humic thiol ligands .

  18. Oxidation kinetics of reaction products formed in uranium metal corrosion

    International Nuclear Information System (INIS)

    Totemeier, T. C.

    1998-01-01

    The oxidation behavior of uranium metal ZPPR fuel corrosion products in environments of Ar-4%O 2 and Ar-20%O 2 were studied using thermo-gravimetric analysis (TGA). These tests were performed to extend earlier work in this area specifically, to assess plate-to-plate variations in corrosion product properties and the effect of oxygen concentration on oxidation behavior. The corrosion products from two relatively severely corroded plates were similar, while the products from a relatively intact plate were not reactive. Oxygen concentration strongly affected the burning rate of reactive products, but had little effect on low-temperature oxidation rates

  19. Oxidation kinetics of reaction products formed in uranium metal corrosion.

    Energy Technology Data Exchange (ETDEWEB)

    Totemeier, T. C.

    1998-04-22

    The oxidation behavior of uranium metal ZPPR fuel corrosion products in environments of Ar-4%O{sub 2} and Ar-20%O{sub 2} were studied using thermo-gravimetric analysis (TGA). These tests were performed to extend earlier work in this area specifically, to assess plate-to-plate variations in corrosion product properties and the effect of oxygen concentration on oxidation behavior. The corrosion products from two relatively severely corroded plates were similar, while the products from a relatively intact plate were not reactive. Oxygen concentration strongly affected the burning rate of reactive products, but had little effect on low-temperature oxidation rates.

  20. Specialists' meeting on fission product release and transport in gas-cooled reactors. Summary report

    International Nuclear Information System (INIS)

    1985-01-01

    The purpose of the Meeting on Fission Product Release and Transport in Gas-Cooled Reactors was to compare and discuss experimental and theoretical results of fission product behaviour in gas-cooled reactors under normal and accidental conditions and to give direction for future development. The technical part of the meeting covered operational experience and laboratory research, activity release, and behaviour of released activity

  1. Specialists' meeting on fission product release and transport in gas-cooled reactors. Summary report

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1985-07-01

    The purpose of the Meeting on Fission Product Release and Transport in Gas-Cooled Reactors was to compare and discuss experimental and theoretical results of fission product behaviour in gas-cooled reactors under normal and accidental conditions and to give direction for future development. The technical part of the meeting covered operational experience and laboratory research, activity release, and behaviour of released activity.

  2. Pesticidal seed coats based on azadirachtin-A: release kinetics, storage life and performance.

    Science.gov (United States)

    Nisar, Keyath; Kumar, Jitendra; Arun Kumar, M B; Walia, Suresh; Shakil, Najam A; Parsad, Rajender; Parmar, Balraj S

    2009-02-01

    Infestation of seeds by pests during storage leads to deterioration in quality. Seed coating is an effective option to overcome the menace. Unlike synthetic fungicidal seed coats, little is known of those based on botanicals. This study aims at developing azadirachtin-A-based pesticidal seed coats to maintain seed quality during storage. Polymer- and clay-based coats containing azadirachtin-A were prepared and evaluated for quality maintenance of soybean seed during storage. Gum acacia, gum tragacanth, rosin, ethyl cellulose, hydroxyethyl cellulose, polyethyl methacrylate, methyl cellulose, polyethylene glycol, polyvinyl chloride, polyvinyl acetate, polyvinyl pyrrolidone and Agrimer VA 6 polymers and the clay bentonite were used as carriers. The time for 50% release (t(1/2)) of azadirachtin-A into water from the seeds coated with the different coats ranged from 8.02 to 21.36 h. The half-life (T(1/2)) of azadirachtin-A in the coats on seed ranged from 4.37 to 11.22 months, as compared with 3.45 months in azadirachtin-A WP, showing an increase by a factor of nearly 1.3-3.3 over the latter. The coats apparently acted as a barrier to moisture to reduce azadirachtin-A degradation and prevented proliferation of storage fungi. Polyethyl methacrylate, polyvinyl acetate and polyvinyl pyrrolidone were significantly superior to the other polymers. Azadirachtin-A showed a significant positive correlation with seed germination and vigour, and negative correlation with moisture content. Effective polymeric carriers for seed coats based on azadirachtin-A are reported. These checked seed deterioration during storage by acting as a barrier to moisture and reduced the degradation of azadirachtin-A.

  3. Effects of preservation conditions of canine feces on in vitro gas production kinetics and fermentation end-products

    NARCIS (Netherlands)

    Bosch, G.; Wrigglesworth, D.J.; Cone, J.W.; Pellikaan, W.F.; Hendriks, W.H.

    2013-01-01

    This study investigated the effect of chilling and freezing (for 24 h) canine feces on in vitro gas production kinetics and fermentation end-product profiles from carbohydrate-rich (in vitro run 1) and protein-rich substrates (in vitro run 2). Feces were collected from 3 adult Retriever-type dogs

  4. The synergistic action of imidacloprid and flumethrin and their release kinetics from collars applied for ectoparasite control in dogs and cats

    Directory of Open Access Journals (Sweden)

    Stanneck Dorothee

    2012-04-01

    Full Text Available Abstract Background The control of tick and flea burdens in dogs and cats has become essential to the control of important and emerging vector borne diseases, some of which are zoonoses. Flea worry and flea bite hypersensitivity are additionally a significant disease entity in dogs and cats. Owner compliance in maintaining the pressure of control measures has been shown to be poor. For these reasons efforts are continuously being made to develop ectoparasiticides and application methods that are safe, effective and easy to apply for pet owners. A new polymer matrix collar has recently been developed which is registered for 8 months use in cats and dogs. The basic properties of this collar have been investigated in several in vitro and in vivo studies. Methods The effects of imidacloprid, flumethrin and the combination were evaluated in vitro by means of whole cell voltage clamp measurement experiments conducted on isolated neuron cells from Spodoptera frugiperda. The in vitro efficacy of the two compounds and the combination against three species of ticks and their life stages and fleas were evaluated in a dry surface glass vial assay. The kinetics of the compounds over time in the collar were evaluated by the change in mass of the collar and measurement of the surface concentrations and concentrations of the actives in the collar matrix by HPLC. Hair clipped from collar treated dogs and cats, collected at various time points, was used to assess the acaricidal efficacy of the actives ex vivo. Results An in vitro isolated insect nerve model demonstrated the synergistic neurotoxic effects of the pyrethroid flumethrin and the neonicotinoid imidacloprid. An in vitro glass vial efficacy and mortality study against various life stages of the ticks Ixodes ricinus, Rhipicephalus sanguineus and Dermacentor reticulatus and against the flea (Ctenocephalides felis demonstrated that the combination of these products was highly effective against these

  5. The synergistic action of imidacloprid and flumethrin and their release kinetics from collars applied for ectoparasite control in dogs and cats

    Science.gov (United States)

    2012-01-01

    Background The control of tick and flea burdens in dogs and cats has become essential to the control of important and emerging vector borne diseases, some of which are zoonoses. Flea worry and flea bite hypersensitivity are additionally a significant disease entity in dogs and cats. Owner compliance in maintaining the pressure of control measures has been shown to be poor. For these reasons efforts are continuously being made to develop ectoparasiticides and application methods that are safe, effective and easy to apply for pet owners. A new polymer matrix collar has recently been developed which is registered for 8 months use in cats and dogs. The basic properties of this collar have been investigated in several in vitro and in vivo studies. Methods The effects of imidacloprid, flumethrin and the combination were evaluated in vitro by means of whole cell voltage clamp measurement experiments conducted on isolated neuron cells from Spodoptera frugiperda. The in vitro efficacy of the two compounds and the combination against three species of ticks and their life stages and fleas were evaluated in a dry surface glass vial assay. The kinetics of the compounds over time in the collar were evaluated by the change in mass of the collar and measurement of the surface concentrations and concentrations of the actives in the collar matrix by HPLC. Hair clipped from collar treated dogs and cats, collected at various time points, was used to assess the acaricidal efficacy of the actives ex vivo. Results An in vitro isolated insect nerve model demonstrated the synergistic neurotoxic effects of the pyrethroid flumethrin and the neonicotinoid imidacloprid. An in vitro glass vial efficacy and mortality study against various life stages of the ticks Ixodes ricinus, Rhipicephalus sanguineus and Dermacentor reticulatus and against the flea (Ctenocephalides felis) demonstrated that the combination of these products was highly effective against these parasites. The release kinetics of

  6. Relationship between in situ degradation kinetics and in vitro gas production fermentation using different mathematical models

    NARCIS (Netherlands)

    Rodrigues, M.A.M.; Cone, J.W.; Ferreira, L.M.M.; Blok, M.C.; Guedes, C.

    2009-01-01

    In vitro and in situ studies were conducted to evaluate the influence of different mathematical models, used to fit gas production profiles of 15 feedstuffs, on estimates of nylon bag organic matter (OM) degradation kinetics. The gas production data were fitted to Exponential, Logistic, Gompertz and

  7. Fermentative production and kinetics of cellulase protein on ...

    African Journals Online (AJOL)

    AJB SERVER

    2006-10-16

    Oct 16, 2006 ... various carbon sources on the production of cellulase using strains of T. reesei QM 9414, 97.177 and Tm3. Pretreatment of sugarcane ... of cellulose chains; endo-1,4-β-D-glucanses which cleave internal glucosidic bonds ..... production, the Leudeking piret model (Rakshit and Sahai, 1991) was developed.

  8. Study on mitigation of in-vessel release of fission products in severe accidents of PWR

    International Nuclear Information System (INIS)

    Huang, G.F.; Tong, L.L.; Li, J.X.; Cao, X.W.

    2010-01-01

    Research highlights: → In-vessel release of fission products in severe accidents for 600 MW PWR is analyzed. → Mitigation effect of primary feed-and-bleed on in-vessel release is investigated. → Mitigation effect of secondary feed-and-bleed on in-vessel release is studied. → Mitigation effect of ex-vessel cooling on in-vessel release is evaluated. - Abstract: During the severe accidents in a nuclear power plant, large amounts of fission products release with accident progression, including in-vessel and ex-vessel release. Mitigation of fission products release is demanded for alleviating radiological consequence in severe accidents. Mitigation countermeasures to in-vessel release are studied for Chinese 600 MW pressurized water reactor (PWR), including feed-and-bleed in primary circuit, feed-and-bleed in secondary circuit and ex-vessel cooling. SBO, LOFW, SBLOCA and LBLOCA are selected as typical severe accident sequences. Based on the evaluation of in-vessel release with different startup time of countermeasure, and the coupling relationship between thermohydraulics and in-vessel release of fission products, some results are achieved. Feed-and-bleed in primary circuit is an effective countermeasure to mitigate in-vessel release of fission products, and earlier startup time of countermeasure is more feasible. Feed-and-bleed in secondary circuit is also an effective countermeasure to mitigate in-vessel release for most severe accident sequences that can cease core melt progression, e.g. SBO, LOFW and SBLOCA. Ex-vessel cooling has no mitigation effect on in-vessel release owing to inevitable core melt and relocation.

  9. Agricultural production - Phase 2. Indonesia. Controlled release pesticide formulations

    International Nuclear Information System (INIS)

    Vollner, L.

    1992-01-01

    At the request of the Government of Indonesia, an IAEA expert undertook a two weeks mission from 2 to 15 April 1991, and continued it from the 9 to 22 November 1991 at the Center for Application of Isotopes and Radiation (CAIR) of the National Atomic Energy Agency, BATAN in Jakarta. Expert discussed the project and carried out experiments together with the staff of the center, introducing shellac (description in part II) as a candidate for controlled release formulations. Formulations of carbofuran, butachlor, 2,4-D and diazinon were carried out, using sand and cocconut shells as carriers. Release rates of a.i. into water have been checked and further work has been discussed. Expert assessed further needs for supply of instruments, accessories and chemicals. (author)

  10. Time-dependent histamine release from stored human blood products

    DEFF Research Database (Denmark)

    Nielsen, Hans Jørgen; Edvardsen, L; Vangsgaard, K

    1996-01-01

    .0 (range 176.0-910.0) nmol/l in whole blood and 475.0 (range 360.0-1560.0) nmol/l in plasma-reduced whole blood, while it was undetectable in SAGM blood. Spontaneous histamine release increased in a time-dependent manner from a median of 6.7 (range 2.2-17.4) nmol/l at the time of storage to 175.0 (range 33...

  11. The coupled kinetics of grain growth and fission product behavior in nuclear fuel under degraded-core accident conditions

    International Nuclear Information System (INIS)

    Rest, J.

    1985-01-01

    The theoretical FASTGRASS-VFP model has been used in the interpretation of fission gas, iodine, and cesium release from (1) irradiated high-burnup LWR fuel in a flowing steam atmosphere during high-temperature, in-cell heating tests (performed at Oak Ridge National Laboratory) and (2) trace-irratiated LWR fuel during severe-fuel-damage (SFD) tests (performed in the PBF reactor in Idaho). A theory of grain boundary sweeping of gas bubbles has been included within the FASTGRASS-VFP formalism. This theory considers the interaction between the moving grain boundary and two distinct size classes of bubbles, those on grain faces and on grain edges, and provides a means of determining whether gas bubbles are caught up and moved along by a moving grain boundary or whether the grain boundary is only temporarily retarded by the bubbles and then breaks away. In addition, as FASTGRASS-VFP provides for a mechanistic calculation of intra- and intergranular fission product behavior, the coupled calculation between fission gas behavior and grain growth is kinetically comprehensive. Results of the analyses demonstrate that intragranular fission product behavior during both types of tests can be interpreted in terms of a grain-growth/grain-boundary-sweeping mechanism that enhances the flow of fission products from within the grains to the grain boundaries. The effect of fuel oxidation by steam on fission product and grain growth behavior is also considered. The FASTGRASS-VFP predictions, measured release rates from the above tests, and previously published release rates are compared and differences between fission product behavior in trace-irradiated and in high-burnup fuel are highlighted. (orig.)

  12. A kinetic study of cation release from a mixed mineral assemblage: implications for determination of uranium uptake

    International Nuclear Information System (INIS)

    Fenton, B.R.; Waite, T.D.

    1996-01-01

    The uptake of U(VI) as UO 2+ 2 on a natural complex mineral assemblage has been studied using batch selective chemical extraction techniques and secondary ion mass spectroscopy (SIMS). Sediments used in the study consisted of a quartz/mica schist collected from the locale of the Koongarra Uranium ore body, Alligator Rivers Uranium Province, Northern Territory, Australia. The bulk sediment was gravity separated into four size fractions, with attention focused on the nominally <25 μm and 250-1000 μm fractions of the bulk sample, in order to assess the effects of particle size on uranium uptake. Investigation of the kinetics of elemental release in the presence of selective extractants show that uranium is bound largely within the iron and aluminium oxyhydroxides of the assemblage, with a highly mobile fraction of this associated with aluminol sites. SIMS analysis of the natural substrate confirms that significant quantities of aluminium are present in surface layers. The effect of particle size on the uptake of uranium indicates very little change with respect to particle size. This finding may be attributed to the presence of highly porous surface coatings. (orig.)

  13. An experimental investigation of fission product release in SLOWPOKE-2 reactors - Data report

    International Nuclear Information System (INIS)

    Harnden, A.M.C.

    1995-09-01

    The results of an investigation into the release of fission products from SLOWPOKE-2 reactors fuelled with a highly-enriched uranium alloy core are detailed in Volume 1. This data report (Volume 2) contains plots of the activity concentrations of the fission products observed in the reactor container at the University of Toronto, Ecole Polytechnique and the Kanata Isotope Production Facility. Release rates from the reactor container water to the gas headspace are also included. (author)

  14. Kinetic Study on Ultrasound Assisted Biodiesel Production from Waste Cooking Oil

    Directory of Open Access Journals (Sweden)

    Widayat

    2015-09-01

    Full Text Available The objective of this research was to study a kinetic model of biodiesel production from waste cooking oil assisted by ultrasound power. The model considered the biodiesel production process as a 2nd order reversible reaction, while its kinetic parameters were estimated using MATLAB, based on data extracted from Hingu, et al. [1]. The data represented experiments under low-frequency ultrasonic wave (20 kHz and variations of temperature, power, catalyst concentration, and alcohol-oil molar ratio. Statistical analysis showed that the proposed model fits well to the experimental data with a determination coefficient (R2 higher than 0.9.

  15. Kinetic study and modeling of biosurfactant production using Bacillus sp.

    Directory of Open Access Journals (Sweden)

    Hesty Heryani

    2017-05-01

    Conclusions: For further development and industrial applications, the modified Gompertz equation is proposed to predict the cell mass and biosurfactant production as a goodness of fit was obtained with this model. The modified Gompertz equation was also extended to enable the excellent prediction of the surface tension.

  16. Kinetics studies of fungal biogas production from certain agricultural ...

    African Journals Online (AJOL)

    Anaerobic degradation of sugar cane and rice husk by cellulolytic fungus was studied respectively at optimum operational condition of concentration, 1:5 w/v of the lignocelluloses: water and temperature of 33oC. The average rates of biogas production determined for sugar cane and rice husk were 57cm3per day and ...

  17. Conjugated Linoleic Acid Production by Bifidobacteria: Screening, Kinetic, and Composition

    Directory of Open Access Journals (Sweden)

    Stefano Raimondi

    2016-01-01

    Full Text Available Conjugated linoleic acids (CLA are positional and geometric isomers of linoleic acid involved in a number of health aspects. In humans, CLA production is performed by gut microbiota, including some species of potential probiotic bifidobacteria. 128 strains of 31 Bifidobacterium species were screened with a spectrophotometric assay to identify novel CLA producers. Most species were nonproducers, while producers belonged to B. breve and B. pseudocatenulatum. GC-MS revealed that CLA producer strains yielded 9cis,11trans-CLA and 9trans,11trans-CLA, without any production of other isomers. Hydroxylated forms of LA were absent in producer strains, suggesting that the myosin-cross-reactive antigen (MCRA protein that exerts hydratase activity is not involved in LA isomerization. Moreover, both CLA producer and nonproducer species bear a MCRA homologue. The strain B. breve WC 0421 was the best CLA producer, converting LA into 68.8% 9cis,11trans-CLA and 25.1% 9trans,11trans-CLA. Production occurred mostly during the lag and the exponential phase. For the first time, production and incorporation of CLA in biomass were assessed. B. breve WC 0421 stored CLA in the form of free fatty acids, without changing the composition of the esterified fatty acids, which mainly occurred in the plasmatic membrane.

  18. Production of fungal lipids : kinetic modeling and process design

    NARCIS (Netherlands)

    Meeuwse, P.

    2011-01-01

    Finding alternatives for fossil fuels is currently urgent. One of the new processes in this field is the production of biodiesel from lipids accumulated by microorganisms. Some yeasts and fungi accumulate lipids when a component needed for growth, usually the N-source, is limiting while the

  19. Testing the behaviour of different kinetic models for uptake/release of radionuclides between water and sediments when implemented in a marine dispersion model

    International Nuclear Information System (INIS)

    Perianez, R.

    2004-01-01

    Three kinetic models for adsorption/release of 137 Cs between water and sediments have been tested when they are included in a previously validated dispersion model of the English Channel. Radionuclides are released to the Channel from La Hague nuclear fuel reprocessing plant (France). The kinetic models are a 1-step model consisting of a single reversible reaction, a 2-step model consisting of two consecutive reversible reactions and an irreversible model consisting of three parallel reactions: two reversible and one irreversible. The models have been tested under three typical situations that correspond to the source terms that can generally be found: instantaneous release, continuous release and redissolution of radionuclides from contaminated sediments. Differences between the models become more evident when contact times between water and sediments are larger (continuous release) and in the case of redissolution from sediments. Time scales for the redissolution process are rather different between the three models. The 1-step model produces a redissolution that is too fast when compared with experimental evidence. The irreversible model requires that saturation effects of the irreversible phase are included. Probably, the 2-step model represents the best compromise between ease and level of detail of the description of sorption/release processes

  20. Structure of a low-population intermediate state in the release of an enzyme product.

    Science.gov (United States)

    De Simone, Alfonso; Aprile, Francesco A; Dhulesia, Anne; Dobson, Christopher M; Vendruscolo, Michele

    2015-01-09

    Enzymes can increase the rate of biomolecular reactions by several orders of magnitude. Although the steps of substrate capture and product release are essential in the enzymatic process, complete atomic-level descriptions of these steps are difficult to obtain because of the transient nature of the intermediate conformations, which makes them largely inaccessible to standard structure determination methods. We describe here the determination of the structure of a low-population intermediate in the product release process by human lysozyme through a combination of NMR spectroscopy and molecular dynamics simulations. We validate this structure by rationally designing two mutations, the first engineered to destabilise the intermediate and the second to stabilise it, thus slowing down or speeding up, respectively, product release. These results illustrate how product release by an enzyme can be facilitated by the presence of a metastable intermediate with transient weak interactions between the enzyme and product.

  1. Production of furfural from palm oil empty fruit bunches: kinetic model comparation

    Science.gov (United States)

    Panjaitan, J. R. H.; Monica, S.; Gozan, M.

    2017-05-01

    Furfural is a chemical compound that can be applied to pharmaceuticals, cosmetics, resins and cleaning compound which can be produced by acid hydrolysis of biomass. Indonesia’s demand for furfural in 2010 reached 790 tons that still imported mostly 72% from China. In this study, reaction kinetic models of furfural production from oil palm empty fruit bunches with submitting acid catalyst at the beginning of the experiment will be determine. Kinetic data will be obtained from hydrolysis of empty oil palm bunches using sulfuric acid catalyst 3% at temperature 170°C, 180°C and 190°C for 20 minutes. From this study, the kinetic model to describe the production of furfural is the kinetic model where generally hydrolysis reaction with an acid catalyst in hemicellulose and furfural will produce the same decomposition product which is formic acid with different reaction pathways. The activation energy obtained for the formation of furfural, the formation of decomposition products from furfural and the formation of decomposition products from hemicellulose is 8.240 kJ/mol, 19.912 kJ/mol and -39.267 kJ / mol.

  2. RSAC, Gamma Doses, Inhalation and Ingestion Doses, Fission Products Inventory after Fission Products Release

    International Nuclear Information System (INIS)

    Richardson, L.C.

    1967-01-01

    1 - Description of problem or function: RSAC generates a fission product inventory from a given set of reactor operating conditions and then computes the external gamma dose, the deposition gamma dose, and the inhalation-ingestion dose to critical body organs as a result of exposure to these fission products. Program output includes reactor operating history, fission product inventory, dosages, and ingestion parameters. 2 - Method of solution: The fission product inventory generated by the reactor operating conditions and the inventory remaining at various times after release are computed using the equations of W. Rubinson in Journal of Chemical Physics, Vol. 17, pages 542-547, June 1949. The external gamma dose and the deposition gamma dose are calculated by determining disintegration rates as a function of space and time, then integrating using Hermite's numerical techniques for the spatial dependence. The inhalation-ingestion dose is determined by the type and quantity of activity inhaled and the biological rate of decay following inhalation. These quantities are integrated with respect to time to obtain the dosage. The ingestion dose is related to the inhalation dose by an input constant

  3. Release of corrosion products from construction materials containing cobalt. Pt.2: Inconel X750

    International Nuclear Information System (INIS)

    Falk, I.

    1978-02-01

    This report describes experimental work aimed at determining the release rate for corrosion products from 18Cr8Ni steel and Inconel X750 in BWR environments. For test purposes these environments were simulated in a high pressure loop, where irradiated samples of the materials were exposed for 720 hours. The amounts of released products were determined using gamma spectrometric analysis. The results show that the release from Inconel X750 is higher than that from 18Cr8Ni steel. The release calculated from Co58 measurements is 7 times higher and from Co60 measurements it is 1.5 times higher. Both the filtered and the deposited fractions of the released corrosion products exhibit the same relative concentrations of Co58 and Co60. (author)

  4. Production and Investigation of Controlled Drug Release Properties of Tamoxifen Loaded Alginate-Gum Arabic Microbeads

    Directory of Open Access Journals (Sweden)

    Rukiye Yavaşer

    2016-08-01

    Full Text Available The entrapment of tamoxifen onto alginate-gum arabic beads and the production of controlled drug release was investigated in this study. The polymeric system that would provide the controlled release of tamoxifen was formed using alginate and gum arabic. In the first phase of the study, the optimization of the alginate-gum arabic beads production was conducted; then the study continued with drug entrapment experiments. Tamoxifen entrapment yield was found to be approximately 90% of initial tamoxifen concentration. In vitro drug release experiments were performed in simulated gastric juice and intestinal fluid where the tamoxifen release was 20% and 53% of the initial drug present, respectively. As a result of this study, it is expected that a valuable contribution to the field of controlled drug release system production is realized.

  5. The influence of naphthaleneacetic acid (NAA) and coumarin on flavonoid production by fungus Phellinus sp.: modeling of production kinetic profiles.

    Science.gov (United States)

    Ma, Xiao-Kui; Li, Le; Peterson, Eric Charles; Ruan, Tingting; Duan, Xiaoyi

    2015-11-01

    For the purpose of improving the fungal production of flavonoids, the influence of naphthaleneacetic acid (NAA) and coumarin on flavonoid production by fungus Phellinus sp. P0988 was investigated by developing the corresponding kinetics of flavonoid production in a 7-L bioreactor. Phellinus sp. was confirmed to form flavonoids in pellets and broth when cultivated in basic medium, and the optimum concentration of NAA and coumarin in medium for flavonoid production were determined to be 0.03 and 0.02 g/L, respectively. The developed unstructured mathematical models were in good agreement with the experimental results with respect to flavonoid production kinetic profiles with NAA and coumarin supplementation at optimum levels and revealed significant accuracy in terms of statistical consistency and robustness. Analysis of these kinetic processes indicated that NAA and coumarin supplementations imposed a stronger positive influence on flavonoid production and substrate consumption compared to their effects on cell growth. The separate addition of NAA and coumarin resulted in enhancements in final product accumulation and productivity, achieving final flavonoid concentrations of 3.60 and 2.75 g/L, respectively, and glucose consumption showed a significant decrease compared to the non-supplemented control as well. Also, the separate presence of NAA and coumarin respectively decreased maintenance coefficients (M s) from 2.48 in the control to 1.39 and 0.22, representing decreases of 43.9 and 91.1 %, respectively. The current study is the first known application of mathematical kinetic models to explore the influence of medium components adding on flavonoid production by fungi.

  6. Oxidation kinetics of hydride-bearing uranium metal corrosion products

    Science.gov (United States)

    Totemeier, Terry C.; Pahl, Robert G.; Frank, Steven M.

    The oxidation behavior of hydride-bearing uranium metal corrosion products from Zero Power Physics Reactor (ZPPR) fuel plates was studied using thermo-gravimetric analysis (TGA) in environments of Ar-4%O 2, Ar-9%O 2, and Ar-20%O 2. Ignition of corrosion product samples from two moderately corroded plates was observed between 125°C and 150°C in all environments. The rate of oxidation above the ignition temperature was found to be dependent only on the net flow rate of oxygen in the reacting gas. Due to the higher net oxygen flow rate, burning rates increased with increasing oxygen concentration. Oxidation rates below the ignition temperature were much slower and decreased with increasing test time. The hydride contents of the TGA samples from the two moderately corroded plates, determined from the total weight gain achieved during burning, were 47-61 wt% and 29-39 wt%. Samples from a lightly corroded plate were not reactive; X-ray diffraction (XRD) confirmed that they contained little hydride.

  7. Oxidation kinetics of hydride-bearing uranium metal corrosion products

    International Nuclear Information System (INIS)

    Totemeier, T.C.; Pahl, R.G.; Frank, S.M.

    1998-01-01

    The oxidation behavior of hydride-bearing uranium metal corrosion products from zero power physics reactor (ZPPR) fuel plates was studied using thermo-gravimetric analysis (TGA) in environments of Ar-4%O 2 , Ar-9%O 2 , and Ar-20%O 2 . Ignition of corrosion product samples from two moderately corroded plates was observed between 125 C and 150 C in all environments. The rate of oxidation above the ignition temperature was found to be dependent only on the net flow rate of oxygen in the reacting gas. Due to the higher net oxygen flow rate, burning rates increased with increasing oxygen concentration. Oxidation rates below the ignition temperature were much slower and decreased with increasing test time. The hydride contents of the TGA samples from the two moderately corroded plates, determined from the total weight gain achieved during burning, were 47-61 wt% and 29-39 wt%. Samples from a lightly corroded plate were not reactive; X-ray diffraction (XRD) confirmed that they contained little hydride. (orig.)

  8. Agricultural production - Phase 2. Indonesia. Controlled release pesticide formulations

    International Nuclear Information System (INIS)

    Vollner, L.

    1991-01-01

    At the request of the Government of Indonesia, an IAEA expert undertook a two weeks (of one month) mission from 2 to 15 April 1991 to the Center for Application of Isotopes and Radiation (CAIR) of BATAN in Jakarta. Expert held a seminar, discussed and carried out experiments on Controlled Release Formulations (CRF). Discussed further experiments, cleaned and reinstalled an ECD of the Shimadzu gas chromatograph and optimized the analytical conditions for chlorinated pesticides. He also developed a project for possible submission to the Government of Germany, to allow the staff of CAIR to undertake a more intensive research and to be able to set up training facilities in his research center in Munich/Germany. He furthermore assessed needs for supply of instruments, accessories and radiolabelled pesticides. An agreement for continuing the scientific and technical mission was obtained with the staff of CAIR, in connection with the DDT-RCM at the end of November 1991, provided approval by IAEA

  9. Kinetic study on ferulic acid production from banana stem waste via mechanical extraction

    Science.gov (United States)

    Zainol, Norazwina; Masngut, Nasratun; Khairi Jusup, Muhamad

    2018-04-01

    Banana is the tropical plants associated with lots of medicinal properties. It has been reported to be a potential source of phenolic compounds such as ferulic acid (FA). FA has excellent antioxidant properties higher than vitamin C and E. FA also have a wide range of biological activities, such as antioxidant activities and anti-microbial activities. This paper presents an experimental and kinetic study on ferulic acid (FA) production from banana stem waste (BSW) via mechanical extraction. The objective of this research is to determine the kinetic parameters in the ferulic acid production. The banana stem waste was randomly collected from the local banana plantation in Felda Lepar Hilir, Pahang. The banana stem juice was mechanically extracted by using sugarcane press machine (KR3176) and further analyzed in high performance liquid chromatography. The differential and integral method was applied to determine the kinetic parameter of the extraction process and the data obtained were fitted into the 0th, 1st and 2nd order of extraction process. Based on the results, the kinetic parameter and R2 value from were 0.05 and 0.93, respectively. It was determined that the 0th kinetic order fitted the reaction processes to best represent the mechanical extraction.

  10. Iridium-Catalyzed Dynamic Kinetic Isomerization: Expedient Synthesis of Carbohydrates from Achmatowicz Rearrangement Products.

    Science.gov (United States)

    Wang, Hao-Yuan; Yang, Ka; Bennett, Scott R; Guo, Sheng-rong; Tang, Weiping

    2015-07-20

    A highly stereoselective dynamic kinetic isomerization of Achmatowicz rearrangement products was discovered. This new internal redox isomerization provided ready access to key intermediates for the enantio- and diastereoselective synthesis of a series of naturally occurring sugars. The nature of the de novo synthesis also enables the preparation of both enantiomers. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. The kinetics of steam-carbon dioxide conversion, rational ways and production catalysts of process gas

    International Nuclear Information System (INIS)

    Khamroev, F.B.

    2016-01-01

    The purpose of the present work is to study the kinetics of steam-carbon dioxide conversion, rational ways and production catalysts of process gas. The experimental equation of steam-carbon methane conversion, heat stability increasing and catalyst efficiency, decreasing of hydrodynamical resistance of catalyst layer were determined.

  12. Reaction kinetics, reaction products and compressive strength of ternary activators activated slag designed by Taguchi method

    NARCIS (Netherlands)

    Yuan, B.; Yu, Q.L.; Brouwers, H.J.H.

    2015-01-01

    This study investigates the reaction kinetics, the reaction products and the compressive strength of slag activated by ternary activators, namely waterglass, sodium hydroxide and sodium carbonate. Nine mixtures are designed by the Taguchi method considering the factors of sodium carbonate content

  13. The kinetics of sterane biological marker release and degradation processes during the hydrous pyrolysis of vitrinite kerogen

    Science.gov (United States)

    Abbott, G. D.; Wang, G. Y.; Eglinton, T. I.; Home, A. K.; Petch, G. S.

    1990-09-01

    The hydrous pyrolysis of a mineral-free vitrinite kerogen (Dinantian coal Lower Carboniferous, North East England) has been carried out at four temperatures (270, 300, 330, and 350°C) for heating times ranging from 2 to 648 h. No significant differences in the epimer-based maturation parameters 20S/(20S + 20R)-5α(H),14α(H),17α(H) C 29 non-rearranged steranes and 22S/(22S+22R)-17α(H), 21β(H) homohopanes were found for a comparison between "expelled oil" and "bitumen" fractions in the resulting pyrolysates. A deuterated model compound ((20R)-5α(H),14α(H),17α(H)-[2,2,4,4-d 4] cholestane) was added to a number of preextracted kerogens (vitrinite, Kimmeridge, Messel and Monterey) and the mixtures were heated under typical hydrous pyrolysis conditions. These experiments showed that direct chiral isomerisation at C-20 in the non-rearranged steranes appears to be relatively unimportant during hydrous pyrolysis which has also been suggested by other recent studies on geological samples.A kinetic model comprising consecutive release and degradation processes was derived to measure first-order rate coefficients from the bi-exponential concentration-time functions of both the (20R)-and (20S)-5α(H),14α(H),17α(H) C 29 "free" steranes in the vitrinite kerogen pyrolysates. This data was then used to calculate preliminary Arrhenius parameters for release ((20S): ΔEa = 125 ± 30 kJ mol -1, A ≈ 4.7 × 10 5 s -1;(20R): ΔEa = 151 ± 39 kJ mol -1, A ≈ 2.7 × 10 9 s -1) and degradation ((20S): ΔEa = 104 ± 22 kJ mol -1, A ≈ 5.8 × 10 3 s -1; (20R): Δa = 87 ± 6 kJ mol -1, A ≈ 2.2 × 10 2 s -1) of the above individual isomers and the values were found to be consistent with a free-radical chain mechanism. This work helps in the greater understanding of the important biomarker reactions that prevail in hydrous pyrolysis experiments.

  14. Kinetics of abiotic nitrous oxide production via oxidation of hydroxylamine by particulate metals in seawater

    Science.gov (United States)

    Cavazos, A. R.; Taillefert, M.; Glass, J. B.

    2016-12-01

    The oceans are a significant of nitrous oxide (N2O) to the atmosphere. Current models of global oceanic N2­O flux focus on microbial N2O cycling and often ignore abiotic reactions, such as the thermodynamically favorable oxidation of the nitrification intermediate hydroxylamine (NH2OH) by Mn(IV) or Fe(III). At circumneutral pH, NH2OH oxidation is more thermodynamically favorable via Mn(IV) than Fe(III) reduction. We characterized the kinetics of NH2OH oxidation in synthetic ocean water at pH 5.1-8.8 using microsensor electrodes to measure real-time N2O production. N2O production rates and yield were greater when NH2OH was oxidized by Mn(IV) than Fe(III). Accordingly, the reduction of Mn(IV) was first order with respect to NH2OH whereas the reduction of Fe(III) was zero order with respect to NH2OH. Interestingly, the order of the reaction with respect to Mn(IV) appears to be negative whereas the reaction is second order with respect to Fe(III). The inverse order with respect to Mn(IV) may be due to the aggregation of particles in seawater, which decreases their surface area and changes their reactivity. Finally, the reaction is first order with respect to protons with Fe(III) as the oxidant but zero order with Mn(IV). The stronger effect of the pH on the reaction with Fe(III) as the oxidant compared to Mn(IV) reflects the stoichiometry of these two reactions, as each mole of N2O produced by Fe(III) reduction consumes eight protons while each mole of N2O produced with Mn(IV) as the oxidant requires only four protons. Our data show that abiotic NH2OH oxidation by Mn(IV) or Fe(III) particles may represent a significant source of N2O in seawater. These findings suggest that abiotic N2O production in marine waters may be significant in areas of the oceans where particulate metals originating from aerosols, dust, or rivers may react with NH2OH released from ammonia-oxidizing microorganisms.

  15. Kinetics and mechanisms of metal retention/release in geochemical processes in soil. 1998 annual progress report

    International Nuclear Information System (INIS)

    Taylor, R.W.

    1998-01-01

    'The long-term fate of toxic metals in soils cannot be precisely predicted, and often remediation recommendations and techniques may be ineffective or unnecessary. This work will generate basic knowledge on the kinetics and mechanism(s) of heavy metal retention/release by soil mineral colloids. The information should assist in improving remediation strategies for toxic heavy metal contaminated soils. The objectives are: (1) To determine the effects of residence time on the mechanisms of Cr(VI), Cu(II), Co(II), Cd(II), Pb(II), and Ni(II) sorption/release on Fe and Al oxide and clay mineral surfaces using kinetic studies coupled to extended x-ray absorption fine structure (EXAFS) spectroscopy and fourier transform infrared (FTIR) spectroscopy. (2) To study the effect of temperature, pH, and phosphate on metal sorption by oxides, and derive thermodynamic parameters to describe the sorption process. As of June, 16, 1997 several clay minerals were tested for their efficiency of removing Cr from aqueous systems. The materials tested--smectite, vermiculites, illites, and kaolinite--represent the natural clay minerals that are abundant in soils and sediments. The clays were used in either their original or reduced (reduced with sodium dithionite) forms. The experimental result indicate that the reduced clays acted as an efficient remover of Cr(VI) from an aqueous system. The XANES spectra of Cr-treated clays provided evidence that the clays reduced Cr(VI) to Cr(III) and immobilized Cr in the clays at the same time. Sodium dithionite applied directly into aqueous systems reduced Cr(VI) to Cr(III), but could not immobilize Cr even in the presence of the clays. The Cr(VI) removal capacity varied with the clay mineral type and the structural Fe content. For the clays used in this study, the removal capacity follows the orders of smectites > vermiculites and illites > kaolinite. Within the same type of clay minerals, reduction of Cr(VI) is highly related to the ferrous iron

  16. Optimization of macronutrient kinetics for biomass production in Nostoc calcicola

    Science.gov (United States)

    Aiyer, Subramanian Seshadri C.; Akshai, A.; Kumar, B. G. Prakash; Ramachandran, S.

    2018-04-01

    To assess the feasibility of Allen and Arnon’s (AA) media addition to increase the biomass productivity, (0, 2.5, 5, 7.5 ml of 10x media concentrate - MC) was added to aerated culture every six days, in two separate conditions i.e., single harvest (SH) and continuous harvest (CH) after 15th day. Results show that with addition of 5 ml of MC produced maximum amount of biomass is 1.32 g/L and 2.88 g/L for Sh and CH respectively. These results show that with addition of 5 ml of MC to an aerated culture every six days with continuous biomass harvesting leads to maximum growth of Nostoc calcicola @25°C

  17. Degradation kinetics and transformation products of chlorophene by aqueous permanganate.

    Science.gov (United States)

    Xu, Xinxin; Chen, Jing; Wang, Siyuan; Ge, Jiali; Qu, Ruijuan; Feng, Mingbao; Sharma, Virender K; Wang, Zunyao

    2018-07-01

    This paper evaluates the oxidation of an antibacterial agent, chlorophene (4-chloro-2-(phenylmethyl)phenol, CP), by permanganate (Mn(VII)) in water. Second-order rate constant (k) for the reaction between Mn(VII) and CP was measured as (2.05 ± 0.05) × 10 1  M -1  s -1 at pH 7.0 for an initial CP concentration of 20.0 μM and Mn(VII) concentration of 60.0 μM. The value of k decreased with increasing pH in the pH range of 5.0-7.0, and then increased with an increase in solution pH from 7.0 to 10.0. The presence of MnO 2 and Fe 3+ in water generally enhanced the removal of CP, while the effect of humic acid was not obvious. Fourteen oxidation products of CP were identified by an electrospray time-of-flight mass spectrometer, and direct oxidation, ring-opening, and decarboxylation were mainly observed in the reaction process. The initial reaction sites of CP by Mn(VII) oxidation were rationalized by density functional theory calculations. Toxicity changes of the reaction solutions were assessed by the luminescent bacteria P. phosphoreum, and the intermediate products posed a relatively low ecological risk during the degradation process. The efficient removal of CP in secondary clarifier effluent and river water demonstrated the potential application of this Mn(VII) oxidation method in water treatment. Copyright © 2018 Elsevier Ltd. All rights reserved.

  18. Environmentally Sustainable Construction Products and Materials – Assessment of release

    DEFF Research Database (Denmark)

    Wahlström, Margareta; Laine-Yliijoki, Jutta; Järnström, helena

    The construction sector consumes yearly about half of all natural resourcesextracted in Europe and their transformation into building products has huge energy demands. Therefore the focus of today’s environmental policy is on the building end-of-life scenarios and material efficiency. Here waste...... hardly any construction product is designed keeping recycling/reuse in mind, the “Design for theEnvironment” -concept is one of the key steps towards increased recycling and reuse and thereby towards minimal environmental impacts. This project has been carried out by VTT with cooperation with the Danish...

  19. Results of dose calculations for NET accidental and normal operation releases of tritium and activation products

    International Nuclear Information System (INIS)

    Raskob, W.; Hasemann, I.

    1992-08-01

    This report documents conditions, data and results of dose calculations for accidental and normal operation releases of tritium and activation products, performed within the NET subtask SEP2.2 ('NET-Benchmark') of the European Fusion Technology Programme. For accidental releases, the computer codes UFOTRI and COSYMA for assessing the radiological consequences, have been applied for both deterministic and probabilistic calculations. The influence on dose estimates of different release times (2 minutes / 1 hour), two release heights (10 m / 150 m), two chemical forms of tritium (HT/HTO), and two different model approaches for the deposition velocity of HTO on soil was investigated. The dose calculations for normal operation effluents were performed using the tritium model of the German regulatory guidelines, parts of the advanced dose assessment model NORMTRI still under development, and the statistical atmospheric dispersion model ISOLA. Accidental and normal operation source terms were defined as follows: 10g (3.7 10 15 Bq) for accidental tritium releases, 10 Ci/day (3.7 10 11 Bq/day) for tritium releases during normal operation and unit releases of 10 9 Bq for accidental releases of activation products and fission products. (orig./HP) [de

  20. Effects of burnup on fission product release and implications for severe fuel damage events

    International Nuclear Information System (INIS)

    Appelhans, A.D.; Cronenberg, A.W.; Carboneau, M.L.

    1984-01-01

    Xe, Kr, and I fission-product release data from (a) Halden tests where release in intact rods was measured during irradiation at burnups to 18,000 MWd/t and fuel temperatures of 800 to 1800 0 K, and (b) Power Burst Facility (PBF) tests where trace-irradiated fuel (approx. = 90 MWd/t) was driven to temperatures of >2400 0 K and fuel liquefaction occurred are discussed and related to fuel morphology. Results from both indicate that the fission-product morphology and fuel restructuring govern release behavior. The Halden tests show low release at beginning of life with a 10-fold increase at burnups in excess of 10,000 MWd/t, due to the development of grain boundary interlinkage at higher burnups. Such dependence of release on morphology characteristics is consistent with findings from the PBF tests, where for trace-irradiated fuel, the absence of interlinkage accounts for the low release rates observed during initial fuel heatup, with subsequent enhanced Xe, Kr, and I release via liquefaction or quench-induced destruction of the grain structure. Morphology is also shown to influence the chemical release form of I and Cs fission products

  1. Modeling the high pressure inactivation kinetics of Listeria monocytogenes on RTE cooked meat products

    DEFF Research Database (Denmark)

    Hereu, A.; Dalgaard, Paw; Garriga, M.

    2012-01-01

    High pressure (HP) inactivation curves of Listeria monocytogenes CTC1034 (ca. 107CFU/g) on sliced RTE cooked meat products (ham and mortadella) were obtained at pressures from 300 to 800MPa. A clear tail shape was observed at pressures above 450MPa and the log-linear with tail primary model...... provided the best fit to the HP-inactivation kinetics. The relationships between the primary kinetic parameters (log kmax and log Nres) and pressure treatments were described by a polynomial secondary model. To estimate HP-inactivation of L. monocytogenes in log (N/N0) over time, a one-step global fitting...

  2. Kinetics of radiolysis of irradiated ligno celluloses into soluble products in water and rumen liquid

    International Nuclear Information System (INIS)

    Tukenmez, I.; Bakioglu, A.T.; Ersen, M.S.

    1997-01-01

    In order to increase the low bio hydrolysis of ligno celluloses in biotechnological and biological processes where these materials are used as raw materials and ruminant feed, the substrates were pretreated with irradiation to induce radiolytic depolymerisation and then kinetics of their radiolysis into soluble products in water and rumen liquid were analyzed. Wheat straw used as a representative lignocellulose substrate was irradiated at 0-2.5 MGy doses at 20''o''C with an optimum equilibrium humidity of 6.6% in Cs-137 gamma irradiator with a dose rate of 1.8 kGy/h, and soluablefractions in water and in situ rumen liquid were determined gravimetrically. Based on these data, a reaction mechanism was proposed for the radiolysis of ligno celluloses into soluble fractions. From the corresponding reaction rate equations with this mechanism a dose dependent kinetics was derived for the radiolysis of ligno celluloses into water/rumen liquid-soluble products. Defined by this kinetics, the threshold doses for the radiolysis of the substrate into water/rumen liquid-soluble products were respectively found 80.6 kGy and 186.0 kGy, and fractional radiolytic decomposition yields 0.193 MGy''-1''.It was emphasized that developed kinetic models may be used for the process design of irradiation pretreatments to improve the bio hydrolysis of ligno celluloses.(2figs. and 17 refs.)

  3. Regulating Drug Release Behavior and Kinetics from Matrix Tablets Based on Fine Particle-Sized Ethyl Cellulose Ether Derivatives: An In Vitro and In Vivo Evaluation

    Directory of Open Access Journals (Sweden)

    Kifayat Ullah Shah

    2012-01-01

    Full Text Available The design and fabrication of sustained/controlled release dosage forms, employing new excipients capable of extending/controlling the release of drugs from the dosage forms over prolonged periods, has worked well in achieving optimally enhanced therapeutic levels of the drugs. In this sense, the objective of this study was to investigate the suitability of selected cellulose ether derivatives for use in direct compression (DC and as efficient drug release controlling agents. Controlled release matrix tablets of ciprofloxacin were prepared at different drug-to-polymer (D : P ratios by direct compression using a fine particle sized ethylcellulose ether derivative (ETHOCEL Standard Premium 7FP as rate controlling polymer. The tablets obtained were evaluated for various physico-chemical characteristics and in-vitro drug release studies were conducted in phosphate buffer (pH 7.4 using PharmaTest dissolution apparatus at constant temperature of 37∘C±0.1. Similarity factor 2 was employed to the release profiles of test formulations and were compared with marketed ciprofloxacin conventional tablets. Drug release mechanism and the kinetics involved were investigated by fitting the release profile data to various kinetic models. It was found that with increasing the proportion of ethylcellulose ether derivative in the matrix, the drug release was significantly extended up to 24 hours. The tablets exhibited zero order or nearly zero order drug transport mechanism. In vivo drug release performance of the developed controlled release tablets and reference conventional tablets containing ciprofloxacin were determined in rabbit serum according to randomized two-way crossover study design using High Performance Liquid Chromatography. Several bioavailability parameters of both the test tablets and conventional tablets including max, max and AUC0- were compared which showed an optimized max and max (<0.05. A good correlation was obtained between in vitro

  4. Kinetics Studies on citric acid production by gamma ray induced mutant of Aspergillus niger

    International Nuclear Information System (INIS)

    Begum, A.A.; Choudhury, N.; Islam, M.S.

    1991-01-01

    Effect of cultural pH and incubation temperature on citric acid yield and kinetic patterns of citric acid fermentation by a natural isolate of aspergillus niger as CA16 and one of its gamma ray induced mutants were studied using cane molasses as growth and fermentation substrate. Mutant strain, 277/30 gave maximum citric acid yield of 85 g/l at pH 3.5 and 28 degree centigrade in molasses medium adjusted to 16% sugar and 25% prescott salt in the medium. Parent strain, CA16 gave a maximum yield of 34 g/l at pH 4.0 and 26 degree centigrade in molasses medium adjusted to 16% sugar and 100% prescott salt in the medium. In kinetic studies, strains showed combination kinetics of citric acid fermentation where product formation is directly related to growth and cell mass and indirectly related to carbohydrate uptake

  5. Esterification kinetics of free fatty acids with supercritical methanol for biodiesel production

    International Nuclear Information System (INIS)

    Alenezi, R.; Leeke, G.A.; Winterbottom, J.M.; Santos, R.C.D.; Khan, A.R.

    2010-01-01

    Non-catalytic esterification of Free Fatty Acids (FFA) with supercritical methanol was studied under reaction conditions of (250-320 deg. C) at 10 MPa. A detailed experimental programme was implemented to investigate the influence of temperature, stirring rate and the molar ratio of methanol to FFA in the feed in a batch-type reaction vessel. The esterification products of FFA with supercritical methanol are Fatty Acids Methyl Esters (FAME; biodiesel) and water. The yield of FAME was found to increase with an increase in temperature, and with an increase in the molar ratio of methanol to FFA. At >850 rpm the yield of FAME was not affected by stirring rate. The rate constants and energy of activation have been numerically evaluated by solving an ordinary differential equation that describes the reaction kinetics. The proposed kinetic model shows a reversible second order reaction and represents all the experimental data satisfactorily, providing deeper insight into the kinetics of the reaction.

  6. Measurement of fission product release during LWR fuel failure

    International Nuclear Information System (INIS)

    Osetek, D.J.; King, J.J.

    1979-01-01

    The PBF is a specialized test reactor consisting of an annular core and a central test space 21 cm in diameter and 91 cm high. A test loop circulates coolant through the central experimental section at typical power reactor conditions. Light-water-reactor-type fuel rods are exposed to power bursts simulating reactivity insertion transients, and to power-cooling-mismatch conditions during which the rods are allowed to operate in film boiling. Fission product concentrations in the test loop coolant are continuously monitored during these transients by a Ge(Li) detector based gamma spectrometer. Automatic batch processing of pulse height spectra results in a list of radionuclide concentrations present in the loop coolant as a function of time during the test. Fission product behavior is then correlated to test parameters and posttest examination of the fuel rods. Data are presented from Test PCM-1

  7. Fission product release measured during fuel damage tests at the Power Burst Facility

    International Nuclear Information System (INIS)

    Osetek, D.J.; Hartwell, J.K.; Vinjamuri, K.; Cronenberg, A.W.

    1985-01-01

    Results are presented of fission product release behavior observed during four severe fuel damage tests on bundles of UO 2 fuel rods. Transient temperatures up to fuel melting were obtained in the tests that included both rapid quench and slow cooldown, low and high (36 GWd/t) burnup fuel and the addition of Ag-In-Cd control rods. Release fractions of major fission product species and release rates of noble gas species are reported. Significant differences in release behavior are discussed between heatup and cooldown periods, low and high burnup fuel and long- and short-lived fission products. Explanations are offered for the probable reasons for the observed differences and recommendations for further studies are given

  8. A new study of the kinetics of curd production in the process of cheese manufacture.

    Science.gov (United States)

    Muñoz, Susana Vargas; Torres, Maykel González; Guerrero, Francisco Quintanilla; Talavera, Rogelio Rodríguez

    2017-11-01

    We studied the role played by temperature and rennet concentration in the coagulation process for cheese manufacture and the evaluation of their kinetics. We concluded that temperature is the main factor that determines the kinetics. The rennet concentration was unimportant probably due to the fast action of the enzyme chymosin. The Dynamic light scattering technique allowed measuring the aggregate's size and their formation kinetics. The volume fraction of solids was determined from viscosity measurements, showing profiles that are in agreement with the size profiles. The results indicate that the formation of the aggregates for rennet cheese is strongly dependent on temperature and rennet concentration. The results revealed that at 35·5 °C the volume fraction of solids has the maximum slope, indicating that at this temperature the curd is formed rapidly. The optimal temperature throughout the process was established. Second-order kinetics were obtained for the process. We observed a quadratic dependence between the rennet volume and the volume fraction of solids (curd), thereby indicating that the kinetics of the curd production should be of order two.

  9. Kinetic study on the effect of temperature on biogas production using a lab scale batch reactor.

    Science.gov (United States)

    Deepanraj, B; Sivasubramanian, V; Jayaraj, S

    2015-11-01

    In the present study, biogas production from food waste through anaerobic digestion was carried out in a 2l laboratory-scale batch reactor operating at different temperatures with a hydraulic retention time of 30 days. The reactors were operated with a solid concentration of 7.5% of total solids and pH 7. The food wastes used in this experiment were subjected to characterization studies before and after digestion. Modified Gompertz model and Logistic model were used for kinetic study of biogas production. The kinetic parameters, biogas yield potential of the substrate (B), the maximum biogas production rate (Rb) and the duration of lag phase (λ), coefficient of determination (R(2)) and root mean square error (RMSE) were estimated in each case. The effect of temperature on biogas production was evaluated experimentally and compared with the results of kinetic study. The results demonstrated that the reactor with operating temperature of 50°C achieved maximum cumulative biogas production of 7556ml with better biodegradation efficiency. Copyright © 2015 Elsevier Inc. All rights reserved.

  10. Evaporation release behavior of volatile fission products from liquid sodium pool to the inert cover gas

    Energy Technology Data Exchange (ETDEWEB)

    Nakagiri, T; Miyahara, S [Oarai Engineering Center, Power Reactor and Nuclear Fuel Development Corp., Oaraimachi, Ibaraki (Japan)

    1996-12-01

    In fuel failure of sodium cooled fast breeder reactors, released volatile fission products (VFPs) such as iodine and cesium from the fuel will be dissolved into the liquid sodium coolant and transferred to the cover vaporization. In the cover gas system of the reactor, natural convection occurs due to temperature differences between the sodium pool and the gas phase. The release rates of VFPs together with sodium vaporization are considered to be controlled by the convection. In this study, three analytical models are developed and examined to calculate the transient release rates using the equilibrium partition coefficients of VFPs. The calculated release rates are compared with experimental results for sodium and sodium iodide. The release rate of sodium is closest to the calculation by the heterogeneous nucleation theory. The release rate of sodium iodide obtained from the experiment is between the release rates calculated by the model based on heat-and-mass transfer analogy and the Hill`s theory. From this study, it is confirmed that the realistic release rate of sodium is able to be calculated by the model based on the heterogeneous nucleation theory. The conservative release rate of sodium iodide is able to be calculated by the model based on the Hill`s theory using the equilibrium partition coefficient of sodium iodide. (author) 7 figs., 1 tab., 3 refs.

  11. Modifying an Active Compound’s Release Kinetic Using a Supercritical Impregnation Process to Incorporate an Active Agent into PLA Electrospun Mats

    Directory of Open Access Journals (Sweden)

    Carol López de Dicastillo

    2018-04-01

    Full Text Available The main objective of this work was to study the release of cinnamaldehyde (CIN from electrospun poly lactic acid (e-PLA mats obtained through two techniques: (i direct incorporation of active compound during the electrospinning process (e-PLA-CIN; and (ii supercritical carbon dioxide (scCO2 impregnation of CIN within electrospun PLA mats (e-PLA/CINimp. The development and characterization of both of these active electrospun mats were investigated with the main purpose of modifying the release kinetic of this active compound. Morphological, structural, and thermal properties of these materials were also studied, and control mats e-PLA and e- PLA CO 2 were developed in order to understand the effect of electrospinning and scCO2 impregnation, respectively, on PLA properties. Both strategies of incorporation of this active compound into PLA matrix resulted in different morphologies that influenced chemical and physical properties of these composites and in different release kinetics of CIN. The electrospinning and scCO2 impregnation processes and the presence of CIN altered PLA thermal and structural properties when compared to an extruded PLA material. The incorporation of CIN through scCO2 impregnation resulted in higher release rate and lower diffusion coefficients when compared to active electrospun mats with CIN incorporated during the electrospinning process.

  12. Kinetics of N-Glycan Release from Human Immunoglobulin G (IgG) by PNGase F: All Glycans Are Not Created Equal.

    Science.gov (United States)

    Huang, Yining; Orlando, Ron

    2017-12-01

    The biologic activity of IgG molecules is modulated by its crystallizable fragment N-glycosylation, and thus, the analysis of IgG glycosylation is critical. A standard approach to analyze glycosylation of IgGs involves the release of the N-glycans by the enzyme peptide N-glycosidase F, which cleaves the linkage between the asparagine residue and innermost N-acetylglucosamine (GlcNAc) of all N-glycans except those containing a 3-linked fucose attached to the reducing terminal GlcNAc residue. The importance of obtaining complete glycan release for accurate quantitation led us to investigate the kinetics of this de-glycosylation reaction for IgG glycopeptides and to determine the effect of glycan structure and amino acid sequence on the rate of glycan release from glycopeptides of IgGs. This study revealed that the slight differences in amino acid sequences did not lead to a statistically different deglycosylation rate. However, statistically significant differences in the deglycosylation rate constants were observed between glycopeptides differing only in glycan structure ( i.e. , nonfucosylated, fucosylated, bisecting-GlcNAc, sialylated, etc .). For example, a single sialic acid residue was found to decrease the rate by a factor of 3. Similar reductions in rate were associated with the presence of a bisecting-GlcNAc. We predict the differences in release kinetics can lead to significant quantitative variations of the glycosylation study of IgGs.

  13. Butia Yatay coconut oil: Process development for biodiesel production and kinetics of esterification with ethanol

    International Nuclear Information System (INIS)

    Zanuttini, M.S.; Pisarello, M.L.; Querini, C.A.

    2014-01-01

    Highlights: • Coconut oil contains high levels of phosphorous and free fatty acids. • Especial degumming process is needed in order to decrease the phosphorous content. • Kinetic constant for esterification reaction decreases as a function of time. • Two-step esterification is more efficient to reduce acidity than one-step. • Approximately 15% of esters are formed by acid-catalyzed transesterification. - Abstract: The aim of this work is to study biodiesel production using Butia Yatay coconut oil. This oil has acid values between 109 and 140 mg KOH/g, and phosphorus content in the order of 600 ppm. A three-step degumming pre-treatment of the raw material was adjusted in order to decrease the phosphorus content to approximately 200 ppm. Afterwards, a two-step esterification followed by transesterification was required in order to obtain a high-quality product. The esterification kinetics was studied including the simultaneous reactions that take place during the esterification of free fatty acids: autocatalysis, triacylglycerides hydrolysis, transesterification, and the reaction of sulphuric acid with the alcohol, being the most important ones. The kinetic parameters for the esterification and autocatalysis reactions were also obtained, being different compared to sunflower oil, due to the presence of short chain fatty acids. The kinetic constant for the esterification reaction rapidly decreases as a function of time, due to the consumption of the catalyst by the alkyl-sulphate formation reaction

  14. Nanostructural control of methane release in kerogen and its implications to wellbore production decline

    Science.gov (United States)

    Ho, Tuan Anh; Criscenti, Louise J.; Wang, Yifeng

    2016-06-01

    Despite massive success of shale gas production in the US in the last few decades there are still major concerns with the steep decline in wellbore production and the large uncertainty in a long-term projection of decline curves. A reliable projection must rely on a mechanistic understanding of methane release in shale matrix-a limiting step in shale gas extraction. Using molecular simulations, we here show that methane release in nanoporous kerogen matrix is characterized by fast release of pressurized free gas (accounting for ~30-47% recovery) followed by slow release of adsorbed gas as the gas pressure decreases. The first stage is driven by the gas pressure gradient while the second stage is controlled by gas desorption and diffusion. We further show that diffusion of all methane in nanoporous kerogen behaves differently from the bulk phase, with much smaller diffusion coefficients. The MD simulations also indicate that a significant fraction (3-35%) of methane deposited in kerogen can potentially become trapped in isolated nanopores and thus not recoverable. Our results shed a new light on mechanistic understanding gas release and production decline in unconventional reservoirs. The long-term production decline appears controlled by the second stage of gas release.

  15. Photodegradation kinetics and transformation products of ketoprofen, diclofenac and atenolol in pure water and treated wastewater

    International Nuclear Information System (INIS)

    Salgado, R.; Pereira, V.J.; Carvalho, G.; Soeiro, R.; Gaffney, V.; Almeida, C.; Cardoso, V. Vale; Ferreira, E.; Benoliel, M.J.

    2013-01-01

    Highlights: ► Direct UV photolysis of 3 pharmaceuticals in pure and waste water was investigated. ► Ketoprofen has higher photodegradion kinetics, followed by diclofenac and atenolol. ► MP/UV photodegradation products were identified for the 3 compounds. ► Photodegradation pathways were proposed to explain the obtained products. ► The persistent photoproducts were identified for each compound. -- Abstract: Pharmaceutical compounds such as ketoprofen, diclofenac and atenolol are frequently detected at relatively high concentrations in secondary effluents from wastewater treatment plants. Therefore, it is important to assess their transformation kinetics and intermediates in subsequent disinfection processes, such as direct ultraviolet (UV) irradiation. The photodegradation kinetics of these compounds using a medium pressure (MP) lamp was assessed in pure water, as well as in filtered and unfiltered treated wastewater. Ketoprofen had the highest time- and fluence-based rate constants in all experiments, whereas atenolol had the lowest values, which is consistent with the corresponding decadic molar absorption coefficient and quantum yield. The fluence-based rate constants of all compounds were evaluated in filtered and unfiltered wastewater matrices as well as in pure water. Furthermore, transformation products of ketoprofen, diclofenac and atenolol were identified and monitored throughout the irradiation experiments, and photodegradation pathways were proposed for each compound. This enabled the identification of persistent transformation products, which are potentially discharged from WWTP disinfection works employing UV photolysis

  16. Photodegradation kinetics and transformation products of ketoprofen, diclofenac and atenolol in pure water and treated wastewater

    Energy Technology Data Exchange (ETDEWEB)

    Salgado, R. [REQUIMTE/CQFB, Chemistry Department, FCT, Universidade Nova de Lisboa, 2829-516 Caparica (Portugal); ESTS-IPS, Escola Superior de Tecnologia de Setúbal do Instituto Politécnico de Setúbal, Rua Vale de Chaves, Campus do IPS, Estefanilha, 2910-761 Setúbal (Portugal); Pereira, V.J. [Instituto de Biologia Experimental e Tecnológica (IBET), Av. da República (EAN), 2784-505 Oeiras (Portugal); Instituto de Tecnologia Química e Biológica (ITQB) – Universidade Nova de Lisboa (UNL), Av. da República, Estação Agronómica Nacional, 2780-157 Oeiras, 5 Portugal (Portugal); Carvalho, G., E-mail: gs.carvalho@fct.unl.pt [REQUIMTE/CQFB, Chemistry Department, FCT, Universidade Nova de Lisboa, 2829-516 Caparica (Portugal); Instituto de Biologia Experimental e Tecnológica (IBET), Av. da República (EAN), 2784-505 Oeiras (Portugal); Soeiro, R. [REQUIMTE/CQFB, Chemistry Department, FCT, Universidade Nova de Lisboa, 2829-516 Caparica (Portugal); Gaffney, V.; Almeida, C. [Institute for Medicines and Pharmaceutical Sciences (iMed.UL), Faculdade de Farmácia da Universidade de Lisboa (FFUL), Av. Prof. Gama Pinto, 1600-049 Lisboa (Portugal); Cardoso, V. Vale; Ferreira, E.; Benoliel, M.J. [Empresa Portuguesa das Águas Livres, S.A., Direcção de Controlo de Qualidade da Água, Laboratório Central, Avenida de Berlim, 15, 1800-031 Lisboa (Portugal); and others

    2013-01-15

    Highlights: ► Direct UV photolysis of 3 pharmaceuticals in pure and waste water was investigated. ► Ketoprofen has higher photodegradion kinetics, followed by diclofenac and atenolol. ► MP/UV photodegradation products were identified for the 3 compounds. ► Photodegradation pathways were proposed to explain the obtained products. ► The persistent photoproducts were identified for each compound. -- Abstract: Pharmaceutical compounds such as ketoprofen, diclofenac and atenolol are frequently detected at relatively high concentrations in secondary effluents from wastewater treatment plants. Therefore, it is important to assess their transformation kinetics and intermediates in subsequent disinfection processes, such as direct ultraviolet (UV) irradiation. The photodegradation kinetics of these compounds using a medium pressure (MP) lamp was assessed in pure water, as well as in filtered and unfiltered treated wastewater. Ketoprofen had the highest time- and fluence-based rate constants in all experiments, whereas atenolol had the lowest values, which is consistent with the corresponding decadic molar absorption coefficient and quantum yield. The fluence-based rate constants of all compounds were evaluated in filtered and unfiltered wastewater matrices as well as in pure water. Furthermore, transformation products of ketoprofen, diclofenac and atenolol were identified and monitored throughout the irradiation experiments, and photodegradation pathways were proposed for each compound. This enabled the identification of persistent transformation products, which are potentially discharged from WWTP disinfection works employing UV photolysis.

  17. Production, detection, storage and release of spin currents

    Directory of Open Access Journals (Sweden)

    Michele Cini

    2015-03-01

    Full Text Available Background: Quantum rings connected to ballistic circuits couple strongly to external magnetic fields if the connection is not symmetric. Moreover, properly connected rings can be used to pump currents in the wires giving raise to a number of interesting new phenomena. At half filling using a time-dependent magnetic field in the plane of the ring one can pump a pure spin current, excited by the the spin–orbit interaction in the ring.Results: Such a magnetic current is even under time reversal and produces an electric field instead of the usual magnetic field. Numerical simulations show that one can use magnetizable bodies as storage units to concentrate and save the magnetization in much the same way as capacitors operating with charge currents store electric charge. The polarization obtained in this way can then be used on command to produce spin currents in a wire. These currents show interesting oscillations while the storage units exchange their polarizations.Conclusion: The magnetic production of spin currents can be a useful alternative to optical excitation and electric field methods.

  18. Interpretation and modelling of fission product Ba and Mo releases from fuel

    Science.gov (United States)

    Brillant, G.

    2010-02-01

    The release mechanisms of two fission products (namely barium and molybdenum) in severe accident conditions are studied using the VERCORS experimental observations. Barium is observed to be mostly released under reducing conditions while molybdenum release is most observed under oxidizing conditions. As well, the volatility of some precipitates in fuel is evaluated by thermodynamic equilibrium calculations. The polymeric species (MoO 3) n are calculated to largely contribute to molybdenum partial pressure and barium volatility is greatly enhanced if the gas atmosphere is reducing. Analytical models of fission product release from fuel are proposed for barium and molybdenum. Finally, these models have been integrated in the ASTEC/ELSA code and validation calculations have been performed on several experimental tests.

  19. Diffusion modeling of fission product release during depressurized core conduction cooldown conditions

    International Nuclear Information System (INIS)

    Martin, R.C.

    1991-01-01

    A simple model for diffusion through the silicon carbide layer of TRISO particles is applied to the data for accident condition testing of fuel spheres for the High-Temperature Reactor program of the Federal Republic of Germany (FRG). Categorization of sphere release of 137 Cs based on fast neutron fluence permits predictions of release with an accuracy comparable to that of the US/FRG accident condition fuel performance model. Calculations are also performed for 85 Kr, 90 Sr, and 110m Ag. Diffusion of cesium through SiC suggests that models of fuel failure should consider fuel performance during repeated accident condition thermal cycling. Microstructural considerations in models of fission product release are discussed. The neutron-induced segregation of silicon within the SiC structure is postulated as a mechanism for enhanced fission product release during accident conditions. As oxygen-enhanced SiC decomposition mechanism is also discussed. (author). 12 refs, 11 figs, 2 tabs

  20. Factors affecting release of ethanol vapour in active modified atmosphere packaging systems for horticultural products

    Directory of Open Access Journals (Sweden)

    Weerawate Utto

    2014-04-01

    Full Text Available The active modified atmosphere packaging (active MAP system , which provides interactive postharvest control , using ethanol vapour controlled release, is one of the current interests in the development of active packaging for horticultural products. A number of published research work have discussed the relationship between the effectiveness of ethanol vapour and its concentration in the package headspace, including its effect on postharvest decay and physiological controls. This is of importance because a controlled release system should release and maintain ethanol vapour at effective concentrations during the desired storage period. A balance among the mass transfer processes of ethanol vapour in the package results in ethanol vapour accumulation in the package headspace. Key factors affecting these processes include ethanol loading, packaging material, packaged product and storage environment (temperature and relative h umidity. This article reviews their influences and discusses future work required to better understand their influences on ethanol vapour release and accumulations in active MAP.

  1. Deposition and release kinetics of nano-TiO2 in saturated porous media: Effects of solution ionic strength and surfactants

    International Nuclear Information System (INIS)

    Godinez, Itzel G.; Darnault, Christophe J.G.; Khodadoust, Amid P.; Bogdan, Dorin

    2013-01-01

    The aggregation, transport and deposition kinetics (i.e. attachment and release) of TiO 2 nanoparticles (nano-TiO 2 ) were investigated as a function of ionic strength and the presence of anionic (sodium dodecylbenzene sulfonate, SDBS) and non-ionic (Triton X-100) surfactants in 100% critical micelle concentration (CMC). The electrolyte concentration of the suspensions dictated the kinetic stability of nano-TiO 2 thus influencing the transport and retention of the nanoaggregates in the saturated porous medium. With increasing ionic strength, the interaction between approaching nano-TiO 2 and nano-TiO 2 already deposited onto collectors surfaces seemed to be more favorable than the interaction between approaching nano-TiO 2 and bare collectors surfaces. The abrupt and gradual reduction in electrolyte concentration during the flushing cycles of the column experiments induced the release of previously deposited nano-TiO 2 suggesting attachment of nano-TiO 2 through secondary energy minimum. Highlights: ► This study focuses on aggregation, transport and deposition kinetics of nano-TiO 2 . ► Ionic strength and surfactants impact nano-TiO 2 transport in saturated porous media. ► Previously deposited nano-TiO 2 serve as preferential sites for subsequent deposition. ► Changes in solution chemistry cause nanodeposits to release a portion of nano-TiO 2 . -- Previously deposited nano-TiO 2 serve as preferential sites for subsequent deposition and changes in solution chemistry cause nanodeposits to release a portion of nano-TiO 2

  2. Release kinetics and mechanisms of trace heavy metals from cement based material; Cinetiques et mecanismes de relargage des metaux lourds presents en traces dans les matrices cimentaires

    Energy Technology Data Exchange (ETDEWEB)

    Moudilou, E.

    2002-12-15

    Chemical species contained in a solid matrix may be transferred to the environment through water leaching. Previous studies of trace metals released from building materials (particularly cement-based ones) highlight an important analytical difficulty. The aim of this study is to determine the kinetics and the mechanisms involved in the release of trace heavy metals (Cr, Cu, Ni, Pb, V and Zn) from industrial cement pastes (usually ranging from 20 to 300 ppm). The development of a dynamic leaching system, named CTG-LEACHCRETE, (used at pH=5, 20 C) which permits the evaluation of the kinetics of trace heavy metals is presented in the first part. Also, innovative solid analysis techniques (ICP-MS-Laser Ablation, local and Grazing Incidence X-rays Diffraction (GIXD) technique) were used to characterise the cement-degraded layers formed during leaching experiments. These techniques enable to monitor the mineralogical evolution and the distribution of trace metals in these areas. The confrontation of these two approaches, kinetic and solid analysis, coupled with a thorough investigation of previously developed models, lead to proposals concerning the mechanisms of release of the trace heavy metals studied. In all the cement pastes studied (CPA-CEM I, CPJ-CEM II/A and CLC-CEM V/A), chromium is trapped in ettringite by substitution SO{sub 4}{sup 2-}(U)CrO{sub 4}{sup 2-} and its release is then controlled by the dissolution of this hydrate. The behaviour of copper, nickel and zinc in degraded areas and in leachates, are correlated to the silicon of the hydrated calcium silicate (CSH), which imply that they are localised there. Lead, was never detected in the leachates. But it is also correlated to the silicon in the degraded layers. (author)

  3. Modeling of in-vessel fission product release including fuel morphology effects for severe accident analyses

    International Nuclear Information System (INIS)

    Suh, K.Y.

    1989-10-01

    A new in-vessel fission product release model has been developed and implemented to perform best-estimate calculations of realistic source terms including fuel morphology effects. The proposed bulk mass transfer correlation determines the product of fission product release and equiaxed grain size as a function of the inverse fuel temperature. The model accounts for the fuel-cladding interaction over the temperature range between 770 K and 3000 K in the steam environment. A separate driver has been developed for the in-vessel thermal hydraulic and fission product behavior models that were developed by the Department of Energy for the Modular Accident Analysis Package (MAAP). Calculational results of these models have been compared to the results of the Power Burst Facility Severe Fuel Damage tests. The code predictions utilizing the mass transfer correlation agreed with the experimentally determined fractional release rates during the course of the heatup, power hold, and cooldown phases of the high temperature transients. Compared to such conventional literature correlations as the steam oxidation model and the NUREG-0956 correlation, the mass transfer correlation resulted in lower and less rapid releases in closer agreement with the on-line and grab sample data from the Severe Fuel Damage tests. The proposed mass transfer correlation can be applied for best-estimate calculations of fission products release from the UO 2 fuel in both nominal and severe accident conditions. 15 refs., 10 figs., 2 tabs

  4. Enhancement of ASTEC and COCOSYS regarding fission product release during MCCI

    Energy Technology Data Exchange (ETDEWEB)

    Agethen, Kathrin [Bochum Univ. (Germany). Reactor Simulation and Safety Group

    2016-10-15

    The focus in this paper is on the enhancement of the fission product release model during molten core concrete interaction in the severe accident analysis codes ASTEC and COCOSYS. After both codes are harmonised and the model interaction as well as the input parameters are adapted, extended model approaches are implemented. These lead to an improvement of the release rates for selected semi-volatile species validated against the ACE tests under ex-vessel conditions.

  5. A high temperature heating device for the study of fission product release from nuclear fuel

    International Nuclear Information System (INIS)

    Svedkauskaite-Le Gore, Jolanta; Kivel, Niko; Guenther-Leopold, Ines

    2010-01-01

    At the Paul Scherrer Institute a high temperature inductive heating furnace, which can heat fuel samples up to 2300 deg. C, has been developed in order to study the release of fission products. The furnace can be directly connected to an inductively coupled plasma mass spectrometer for online monitoring of the released elements and does not require their trapping before measurement. This paper describes the design of the inductive heating furnace, discusses its operating parameters, limitations and illustrates foreseen applications. (authors)

  6. The Kinetic of Biogas Production Rate from Cattle Manure in Batch Mode

    OpenAIRE

    Budiyono; I N. Widiasa; S. Johari; Sunarso

    2010-01-01

    In this study, the kinetic of biogas production was studied by performing a series laboratory experiment using rumen fluid of animal ruminant as inoculums. Cattle manure as substrate was inoculated by rumen fluid to the anaerobic biodigester. Laboratory experiments using 400 ml biodigester were performed in batch operation mode. Given 100 grams of fresh cattle manure was fed to each biodigester and mixed with rumen fluid by manure : rumen weight ratio of 1:1 (MR11). The operating temperatures...

  7. State and Kinetic Parameters Estimation of Bio-Ethanol Production with Immobilized Cells

    OpenAIRE

    Mihaylova, Iva; Popova, Silviya; Kostov, Georgi; Ignatova, Maya; Lubenova, Velislava; Naydenova, Vessela; Pircheva, Desislava; Angelov, Mihail

    2013-01-01

    In this paper, state and kinetic parameters estimation based on extended Kalman filter (EKF) is proposed. Experimental data from alcoholic fermentation process with immobilized cells is used. The measurements of glucose and ethanol concentration are used as on-line measurements for observers design and biomass concentration is used for results verification. Biomass, substrate and product concentrations inside immobilized compounds are estimated using the proposed algorithm. Monitoring of the ...

  8. Usefulness of radiatively obtained acrylamide polymers for production of drug forms with controlled release of the therapeutic component

    International Nuclear Information System (INIS)

    Mosiniak, T.; Switek, W.

    1988-01-01

    Using 60 Co gamma radiation as a factor initiating polymerization and cross-linking of polymers, polyacrylamide matrices were formed with the following therapeutic agents: aspirin, amidopyrin, sodium salicylate. Gamma radiation doses ranged from 3.5 to 22.5 kGy, dose rate was 0.138 Gy x s -1 . Kinetics of the therapeutic agent release from the matrix polymers was determined by measurement of per cent of the drug release in the course of time and calculations of release rate constants. The preparations containing slowly released drugs were obtained. 12 figs., 2 tabs., 11 refs. (author)

  9. Freedom: a transient fission-product release model for radioactive and stable species

    International Nuclear Information System (INIS)

    Macdonald, L.D.; Lewis, B.J.; Iglesias, F.C.

    1989-05-01

    A microstructure-dependent fission-gas release and swelling model (FREEDOM) has been developed for UO 2 fuel. The model describes the transient release behaviour for both the radioactive and stable fission-product species. The model can be applied over the full range of operating conditions, as well as for accident conditions that result in high fuel temperatures. The model accounts for lattice diffusion and grain-boundary sweeping of fusion products to the grain boundaries, where the fission gases accumulate in grain-face bubbles as a result of vacancy diffusion. Release of fission-gas to the free void of the fuel element occurs through the interlinkage of bubbles and cracks on the grain boundaries. This treatment also accounts for radioactive chain decay and neutron-induced transmutation effects. These phenomena are described by mass balance equations which are numerically solved using a moving-boundary, finite-element method with mesh refinement. The effects of grain-face bubbles on fuel swelling and fuel thermal conductivity are included in the ELESIM fuel performance code. FREEDOM has an accuracy of better than 1% when assessed against an analytic solution for diffusional release. The code is being evaluated against a fuel performance database for stable gas release, and against sweep-gas and in-cell fission-product release experiments at Chalk River for active species

  10. Fission product release in conditions of a spent fuel pool severe accident

    International Nuclear Information System (INIS)

    Ohai, Dumitru

    2007-01-01

    Full text: Depending on the residence time, fuel burnup, and fuel rack configuration, there may be sufficient decay heat for the fuel clad to heat up, swell, and burst in case of a loss of pool water. Initiating event categories can be: loss of offsite power from events initiated by severe weather, internal fire, loss of pool cooling, loss of coolant inventory, seismic event, aircraft impact, tornado, missile attack. The breach in the clad releases the radioactive gases present in the gap between the fuel and clad, what is called 'gap release'. If the fuel continues to heat up, the zirconium clad will reach the point of rapid oxidation in air. This reaction of zirconium and air, or zirconium and steam is exothermic. The energy released from the reaction, combined with the fuel's decay energy, can cause the reaction to become self-sustaining and ignite the zirconium. The increase in heat from the oxidation reaction can also raise the temperature in adjacent fuel assemblies and propagate the oxidation reaction. Simultaneously, the sintered UO 2 pellets resulting from pins destroying are oxidized. Due to the self-disintegration of pellets by oxidation, fission gases and low volatile fission products are released. The release rate, the chemical nature and the amount of fission products depend on powder granulation distribution and environmental conditions. The zirconium burning and pellets self-disintegration will result in a significant release of spent fuel fission products that will be dispersed from the reactor site. (author)

  11. Release of intracellular Calcium increase production of mitochondrial reactive oxygen species in renal distal epithelial cells

    DEFF Research Database (Denmark)

    Bjerregaard, Henning F.

    peroxide (H2O2) has traditionally been regarded as toxic by-products of aerobic metabolism. However, recent findings indicate that H2O2 act as a signalling molecule. The aim of the present study was to monitor, in real time, the rates of ROS generation in order to directly determine their production......Release of intracellular Calcium increase production of mitochondrial reactive oxygen species in renal distal epithelial cells. Henning F. Bjerregaard, Roskilde University, Department of Science, Systems and Models , 4000 Roskilde, Denmark. HFB@ RUC.DK Reactive oxygen species (ROS) like, hydrogen...... to G-protein stimulation of phospholipase C and release of inositol -3 phosphate. Cd (0.4 mM) treatment of A6 cells enhanced the ROS production after one minutes incubation. The production rate was constant for at least 10 to 20 min. Experiments showed that the Cd induced increase in ROS production...

  12. Modeling nitrous oxide production and reduction in soil through explicit representation of denitrification enzyme kinetics.

    Science.gov (United States)

    Zheng, Jianqiu; Doskey, Paul V

    2015-02-17

    An enzyme-explicit denitrification model with representations for pre- and de novo synthesized enzymes was developed to improve predictions of nitrous oxide (N2O) accumulations in soil and emissions from the surface. The metabolic model of denitrification is based on dual-substrate utilization and Monod growth kinetics. Enzyme synthesis/activation was incorporated into each sequential reduction step of denitrification to regulate dynamics of the denitrifier population and the active enzyme pool, which controlled the rate function. Parameterizations were developed from observations of the dynamics of N2O production and reduction in soil incubation experiments. The model successfully reproduced the dynamics of N2O and N2 accumulation in the incubations and revealed an important regulatory effect of denitrification enzyme kinetics on the accumulation of denitrification products. Pre-synthesized denitrification enzymes contributed 20, 13, 43, and 62% of N2O that accumulated in 48 h incubations of soil collected from depths of 0-5, 5-10, 10-15, and 15-25 cm, respectively. An enzyme activity function (E) was defined to estimate the relative concentration of active enzymes and variation in response to environmental conditions. The value of E allows for activities of pre-synthesized denitrification enzymes to be differentiated from de novo synthesized enzymes. Incorporating explicit representations of denitrification enzyme kinetics into biogeochemical models is a promising approach for accurately simulating dynamics of the production and reduction of N2O in soils.

  13. Continuous production of biodiesel under supercritical methyl acetate conditions: Experimental investigation and kinetic model.

    Science.gov (United States)

    Farobie, Obie; Matsumura, Yukihiko

    2017-10-01

    In this study, biodiesel production by using supercritical methyl acetate in a continuous flow reactor was investigated for the first time. The aim of this study was to elucidate the reaction kinetics of biodiesel production by using supercritical methyl. Experiments were conducted at various reaction temperatures (300-400°C), residence times (5-30min), oil-to-methyl acetate molar ratio of 1:40, and a fixed pressure of 20MPa. Reaction kinetics of biodiesel production with supercritical methyl acetate was determined. Finally, biodiesel yield obtained from this method was compared to that obtained with supercritical methanol, ethanol, and MTBE (methyl tertiary-butyl ether). The results showed that biodiesel yield with supercritical methyl acetate increased with temperature and time. The developed kinetic model was found to fit the experimental data well. The reactivity of supercritical methyl acetate was the lowest, followed by that of supercritical MTBE, ethanol, and methanol, under the same conditions. Copyright © 2017. Published by Elsevier Ltd.

  14. Kinetics, Ca2+ dependence, and biophysical properties of integrin-mediated mechanical modulation of transmitter release from frog motor nerve terminals

    Science.gov (United States)

    Chen, B. M.; Grinnell, A. D.

    1997-01-01

    Neurotransmitter release from frog motor nerve terminals is strongly modulated by change in muscle length. Over the physiological range, there is an approximately 10% increase in spontaneous and evoked release per 1% muscle stretch. Because many muscle fibers do not receive suprathreshold synaptic inputs at rest length, this stretch-induced enhancement of release constitutes a strong peripheral amplifier of the spinal stretch reflex. The stretch modulation of release is inhibited by peptides that block integrin binding of natural ligands. The modulation varies linearly with length, with a delay of no more than approximately 1-2 msec and is maintained constant at the new length. Moreover, the stretch modulation persists in a zero Ca2+ Ringer and, hence, is not dependent on Ca2+ influx through stretch activated channels. Eliminating transmembrane Ca2+ gradients and buffering intraterminal Ca2+ to approximately normal resting levels does not eliminate the modulation, suggesting that it is not the result of release of Ca2+ from internal stores. Finally, changes in temperature have no detectable effect on the kinetics of stretch-induced changes in endplate potential (EPP) amplitude or miniature EPP (mEPP) frequency. We conclude, therefore, that stretch does not act via second messenger pathways or a chemical modification of molecules involved in the release pathway. Instead, there is direct mechanical modulation of release. We postulate that tension on integrins in the presynaptic membrane is transduced mechanically into changes in the position or conformation of one or more molecules involved in neurotransmitter release, altering sensitivity to Ca2+ or the equilibrium for a critical reaction leading to vesicle fusion.

  15. Aqueous chlorination of mefenamic acid: kinetics, transformation by-products and ecotoxicity assessment.

    Science.gov (United States)

    Adira Wan Khalit, Wan Nor; Tay, Kheng Soo

    2016-05-18

    Mefenamic acid (Mfe) is one of the most frequently detected nonsteroidal anti-inflammatory drugs in the environment. This study investigated the kinetics and the transformation by-products of Mfe during aqueous chlorination. The potential ecotoxicity of the transformation by-products was also evaluated. In the kinetic study, the second-order rate constant (kapp) for the reaction between Mfe and free available chlorine (FAC) was determined at 25 ± 0.1 °C. The result indicated that the degradation of Mfe by FAC is highly pH-dependent. When the pH was increased from 6 to 8, it was found that the kapp for the reaction between Mfe and FAC was decreased from 16.44 to 4.4 M(-1) s(-1). Characterization of the transformation by-products formed during the chlorination of Mfe was carried out using liquid chromatography-quadrupole time-of-flight accurate mass spectrometry. Four major transformation by-products were identified. These transformation by-products were mainly formed through hydroxylation, chlorination and oxidation reactions. Ecotoxicity assessment revealed that transformation by-products, particularly monohydroxylated Mfe which is more toxic than Mfe, can be formed during aqueous chlorination.

  16. Fission product release modelling for application of fuel-failure monitoring and detection - An overview

    Energy Technology Data Exchange (ETDEWEB)

    Lewis, B.J., E-mail: lewibre@gmail.com [Department of Chemistry and Chemical Engineering, Royal Military College of Canada, Kingston, Ontario, K7K 7B4 (Canada); Chan, P.K.; El-Jaby, A. [Department of Chemistry and Chemical Engineering, Royal Military College of Canada, Kingston, Ontario, K7K 7B4 (Canada); Iglesias, F.C.; Fitchett, A. [Candesco Division of Kinectrics Inc., 26 Wellington Street East, 3rd Floor, Toronto, Ontario M5E 1S2 (Canada)

    2017-06-15

    A review of fission product release theory is presented in support of fuel-failure monitoring analysis for the characterization and location of defective fuel. This work is used to describe: (i) the development of the steady-state Visual-DETECT code for coolant activity analysis to characterize failures in the core and the amount of tramp uranium; (ii) a generalization of this model in the STAR code for prediction of the time-dependent release of iodine and noble gas fission products to the coolant during reactor start-up, steady-state, shutdown, and bundle-shifting manoeuvres; (iii) an extension of the model to account for the release of fission products that are delayed-neutron precursors for assessment of fuel-failure location; and (iv) a simplification of the steady-state model to assess the methodology proposed by WANO for a fuel reliability indicator for water-cooled reactors.

  17. Consequences of tritium release to water pathways from postulated accidents in a DOE production reactor

    International Nuclear Information System (INIS)

    O'Kula, K.R.; Olson, R.L.; Hamby, D.M.

    1991-01-01

    A full-scale PRA of a DOE production reactor has been completed that considers full release of tritium as part of the severe accident source term. Two classes of postulated reactor accidents, a loss-of-moderator pumping accident and a loss-of-coolant accident, are used to bound the expected dose consequence from liquid pathway release. Population doses from the radiological release associated with the two accidents are compared for aqueous discharge and atmospheric release modes. The expectation values of the distribution of possible values for the societal effective dose equivalent to the general public, given a tritium release to the atmosphere, is 2.8 person-Sv/PBq (9.9 x 10 -3 person-rem/Ci). The general public drinking water dose to downstream water consumers is 6.5 x 10 -2 person-Sv/Pbq (2.4 x 10 -4 person-rem/Ci) for aqueous releases to the surface streams eventually reaching the Savannah River. Negligible doses are calculated for freshwater fish and saltwater invertebrate consumption, irrigation, and recreational use of the river, given that an aqueous release is assumed to occur. Relative to the balance of fission products released in a hypothetical severe accident, the tritium-related dose is small. This study suggests that application of regional models (1610 km radius) will indicate larger dose consequences from short-term tritium release to the atmosphere than from comparable tritium source terms to water pathways. However, the water pathways assessment is clearly site-specific, and the overall aqueous dose will be dependent on downstream receptor populations and uses of the river

  18. Release of fission products during controlled loss-of-coolant accidents and hypothetical core meltdown accidents

    International Nuclear Information System (INIS)

    Albrecht, H.; Malinauskas, A.P.

    1978-01-01

    A few years ago the Projekt Nukleare Sicherheit joined the United States Nuclear Regulatory Commission in the development of a research program which was designed to investigate fission product release from light water reactor fuel under conditions ranging from spent fuel shipping cask accidents to core meltdown accidents. Three laboratories have been involved in this cooperative effort. At Argonne National Laboratory (ANL), the research effort has focused on noble gas fission product release, whereas at Oak Ridge National Laboratory (ORNL) and at Kernforschungszentrum Karlsruhe (KfK), the studies have emphasized the release of species other than the noble gases. In addition, the ORNL program has been directed toward the development of fission product source terms applicable to analyses of spent fuel shipping cask accidents and controlled loss-of-coolant accidents, and the KfK program has been aimed at providing similar source terms which are characteristic of core meltdown accidents. The ORNL results are presented for fission product release from defected fuel rods into a steam atmosphere over the temperature range 500 to 1200 0 C, and the KfK results for release during core meltdown sequences

  19. Comparison of fission product release predictions using PARFUME with results from the AGR-1 irradiation experiment

    International Nuclear Information System (INIS)

    Collin, Blaise P.; Petti, David A.; Demkowicz, Paul A.; Maki, John T.

    2014-01-01

    The PARFUME (PARticle FUel ModEl) code was used to predict fission product release from tristructural isotropic (TRISO) coated fuel particles and compacts during the first irradiation experiment (AGR-1) of the Advanced Gas Reactor Fuel Development and Qualification program. The PARFUME model for the AGR-1 experiment used the fuel compact volume average temperature for each of the 620 days of irradiation to calculate the release of fission products silver, cesium, and strontium from a representative particle for a select number of AGR-1 compacts. Post-irradiation examination (PIE) measurements provided data on release of fission products from fuel compacts and fuel particles, and retention of fission products in the compacts outside of the silicon carbide (SiC) layer. PARFUME-predicted fractional release of these fission products was determined and compared to the PIE measurements. Results show an overall over-prediction of the fractional release of cesium by PARFUME. For particles with failed SiC layers, the over-prediction is by a factor of about two, corresponding to an over-estimation of the diffusivity in uranium oxycarbide (UCO) by a factor of about 100. For intact particles, whose release is much lower, the over-prediction is by an average of about an order of magnitude, which could additionally be attributed to an over-estimated diffusivity in SiC by about 30%. The release of strontium from intact particles is also over-estimated by PARFUME, which also points towards an over-estimated diffusivity of strontium in either SiC or UCO, or possibly both. The measured strontium fractional release from intact particles varied considerably from compact to compact, making it difficult to assess the effective over-estimation of the diffusivities. Furthermore, the release of strontium from particles with failed SiC is difficult to observe experimentally due to the release from intact particles, preventing any conclusions to be made on the accuracy or validity of the

  20. Kinetic model of biodiesel production using immobilized lipase Candida antarctica lipase B

    DEFF Research Database (Denmark)

    Fedosov, Sergey; Brask, Jesper; Pedersen, Anders K.

    2013-01-01

    We have designed a kinetic model of biodiesel production using Novozym 435 (Nz435) with immobilized Candida antarctica lipase B (CALB) as a catalyst. The scheme assumed reversibility of all reaction steps and imitated phase effects by introducing various molecular species of water and methanol....... Residual enzymatic activity in biodiesel of standard quality causes increase of D above its specification level because of the reaction 2M↔D+G. Filtration or alkaline treatment of the product prior to storage resolves this problem. The optimal field of Nz435 application appears to be decrease of F, M, D...

  1. Characterization and chemistry of fission products released from LWR fuel under accident conditions

    International Nuclear Information System (INIS)

    Norwood, K.S.; Collins, J.L.; Osborne, M.F.; Lorenz, R.A.; Wichner, R.P.

    1984-01-01

    Segments from commercial LWR fuel rods have been tested at temperatures between 1400 and 2000 0 C in a flowing steam-helium atmosphere to simulate severe accident conditions. The primary goals of the tests were to determine the rate of fission product release and to characterize the chemical behavior. This paper is concerned primarily with the identification and chemical behavior of the released fission products with emphasis on antimony, cesium, iodine, and silver. The iodine appeared to behave primarily as cesium iodide and the antimony and silver as elements, while cesium behavior was much more complex. 17 refs., 7 figs., 1 tab

  2. Levofloxacin oxidation by ozone and hydroxyl radicals: kinetic study, transformation products and toxicity.

    Science.gov (United States)

    Hamdi El Najjar, Nasma; Touffet, Arnaud; Deborde, Marie; Journel, Romain; Leitner, Nathalie Karpel Vel

    2013-10-01

    This work was carried out to investigate the fate of the antibiotic levofloxacin upon oxidation with ozone and hydroxyl radicals. A kinetic study was conducted at 20 °C for each oxidant. Ozonation experiments were performed using a competitive kinetic method with carbamazepin as competitor. Significant levofloxacin removal was observed during ozonation and a rate constant value of 6.0×10(4) M(-1) s(-1) was obtained at pH 7.2. An H2O2/UV system was used for the formation of hydroxyl radicals HO. The rate constant of HO was determined in the presence of a high H2O2 concentration. The kinetic expressions yielded a [Formula: see text] value of 4.5×10(9) M(-1) s(-1) at pH 6.0 and 5.2×10(9) M(-1) s(-1) at pH 7.2. These results were used to develop a model to predict the efficacy of the ozonation process and pharmaceutical removal was estimated under different ozonation conditions (i.e. oxidant concentrations and contact times). The results showed that levofloxacin was completely degraded by molecular ozone during ozonation of water and that hydroxyl radicals had no effect in real waters conditions. Moreover, LC/MS/MS and toxicity assays using Lumistox test were performed to identify ozonation transformation products. Under these conditions, four transformation products were observed and their chemical structures were proposed. The results showed an increase in toxicity during ozonation, even after degradation of all of the observed transformation products. The formation of other transformation products not identified under our experimental conditions could be responsible for the observed toxicity. These products might be ozone-resistant and more toxic to Vibrio fisheri than levofloxacin. Copyright © 2013 Elsevier Ltd. All rights reserved.

  3. Fission-product release modelling in the ASTEC integral code: the status of the ELSA module

    International Nuclear Information System (INIS)

    Plumecocq, W.; Kissane, M.P.; Manenc, H.; Giordano, P.

    2003-01-01

    Safety assessment of water-cooled nuclear reactors encompasses potential severe accidents where, in particular, the release of fission products (FPs) and actinides into the reactor coolant system (RCS) is evaluated. The ELSA module is used in the ASTEC integral code to model all releases into the RCS. A wide variety of experiments is used for validation: small-scale CRL, ORNL and VERCORS tests; large-scale Phebus-FP tests; etc. Being a tool that covers intact fuel and degraded states, ELSA is being improved maximizing the use of information from degradation modelling. Short-term improvements will include some treatment of initial FP release due to intergranular inventories and implementing models for release of additional structural materials (Sn, Fe, etc.). (author)

  4. Tests on the release of fission and activation products during core meltdown

    Energy Technology Data Exchange (ETDEWEB)

    Albrecht, H; Krause, W; Wild, H

    1976-01-01

    The first available results are related to tests in which the release of the main components of the core melt, namely the steel, zircaloy and uranium components, was determined using ThO/sub 2/ crucibles. The release products are dispersed onto the pipe walls of the transport system and the measuring filters which were installed at about 1 m distance from the melt crucibles. Of these, only the precipitates on the filters have been analyzed so far. In the tests under air, the release was clearly dependent on the maximum temperature reached. The release values for Mo and Mn were the highest with 5-10%; uranium with 0.1% on the other hand, was the lowest. In a steam atmosphere over the melt, the analysis of the filter precipitates for all elements gave considerably lower values than with the tests in air.

  5. Theoretical analysis of knock-out release of fission products from nuclear fuels

    International Nuclear Information System (INIS)

    Yamagishi, S.

    1975-01-01

    The knock-out release of fission products is studied theoretically. The general equations of knock-out release are derived, assuming that a fission fragment passing through the surface of nuclear fuels knocks out a local region of the surface with an effective thickness and an effective cross-sectional area. Using these equations, the knock-out release of fission gases is calculated for various cases. The conditions under which the knock-out coefficients (the average number of uranium atoms knocked out by one fission fragment) is obtainable are clarified by experiments on the knock-out release of fission gases. A method of determining the effective thickness and the effective cross-sectional area of a knock-out region is proposed. (Auth.)

  6. An evaluation of nodalization/decay heat/ volatile fission product release models in ISAAC code

    Energy Technology Data Exchange (ETDEWEB)

    Song, Yong Mann; Park, Soo Yong; Kim, Dong Ha

    2003-03-01

    An ISAAC computer code, which was developed for a Level-2 PSA during 1995, has developed mainly with fundamental models for CANDU-specific severe accident progression and also the accident-analyzing experiences are limited to Level-2 PSA purposes. Hence the system nodalization model, decay model and volatile fission product release model, which are known to affect fission product behavior directly or indirectly, are evaluated to both enhance understanding for basic models and accumulate accident-analyzing experiences. As a research strategy, sensitivity studies of model parameters and sensitivity coefficients are performed. According to the results from core nodalization sensitivity study, an original 3x3 nodalization (per loop) method which groups horizontal fuel channels into 12 representative channels, is evaluated to be sufficient for an optimal scheme because detailed nodalization methods have no large effect on fuel thermal-hydraulic behavior, total accident progression and fission product behavior. As ANSI/ANS standard model for decay heat prediction after reactor trip has no needs for further model evaluation due to both wide application on accident analysis codes and good comparison results with the ORIGEN code, ISAAC calculational results of decay heat are used as they are. In addition, fission product revaporization in a containment which is caused by the embedded decay heat, is demonstrated. The results for the volatile fission product release model are analyzed. In case of early release, the IDCOR model with an in-vessel Te release option shows the most conservative results and for the late release case, NUREG-0772 model shows the most conservative results. Considering both early and late release, the IDCOR model with an in-vessel Te bound option shows mitigated conservative results.

  7. The Physico-Mechanical Properties and Release Kinetics of Eugenol in Chitosan-Alginate Polyelectrolyte Complex Films as Active Food Packaging

    Directory of Open Access Journals (Sweden)

    Baiq Amelia Riyandari

    2018-02-01

    Full Text Available A study of eugenol release and its kinetics model from chitosan-alginate polyelectrolyte complex (PEC films has been conducted. Some factors that affected the eugenol release were also studied, including the composition of chitosan-alginate PEC and the concentration of eugenol. The chitosan-alginate-eugenol PEC films were synthesized at pH ± 4.0, then the PEC films were characterized using a Fourier-transform infrared spectroscopy (FTIR spectrophotometer. An investigation of the films’ properties was also conducted, including morphology analysis using a scanning electron microscope (SEM, differential thermal analysis (DTA / thermogravimetric analysis (TGA, mechanical strength, transparency testing, water absorption, and water vapor permeability. The release of eugenol was investigated through in vitro assay in ethanol 96% (v/v for four days, and the concentration of eugenol was measured using an ultraviolet-visible (UV-Vis spectrophotometer. The characterization of the films using FTIR showed that the formation of PEC occurred through ionic interaction between the amine groups (–NH3+of the chitosan and the carboxylate groups (–COO– of the alginate. The result showed that the composition of chitosan-alginate PEC and the concentration of eugenol can affect the release of eugenol from PEC films. A higher concentration of alginate and eugenol could increase the concentration of eugenol that was released from the films. The mechanism for the release of eugenol from chitosan-alginate PEC films followed the Korsmeyer-Peppas model with an n value of < 0.5, which means the release mechanism for eugenol was controlled by a Fickian diffusion process. The antioxidant activity assay of the films using the 2,2-diphenyl-1-picrylhydrazyl (DPPH method resulted in a high radical scavenging activity (RSA value of 55.99% in four days.

  8. Effects of heparin on platelet aggregation and release and thromboxane A2 production

    International Nuclear Information System (INIS)

    Mohammad, S.F.; Anderson, W.H.; Smith, J.B.; Chuang, H.Y.; Mason, R.G.

    1981-01-01

    Heparin, when added to citrated platelet-rich plasma (PRP), caused potentiation of platelet aggregation and the release reaction induced by the aggregating agents adenosine diphosphate (ADP), arachidonic acid, collagen, and epinephrine. At low concentrations (4.7 x 10(-5) M) arachidonic acid failed to cause aggregation of platelets in citrated PRP. However, in the presence of heparin, the same concentration of arachidonic acid caused aggregation. Examination of PRP for the presence of thromboxane A2 (TxA2) by use of a bioassay revealed that heparin also stimulated release of TxA2. This finding indicated that platelets released more TxA2 when they were challenged by low concentrations of arachidonic acid in the presence of heparin than in its absence. Platelets were labeled with 3 H-arachidonic acid and 14 C-serotonin, and attempts were made to determine whether heparin stimulated the platelet release reaction first with subsequent increased production of TxA2, or alternatively, whether heparin stimulated TxA2 production first with subsequent enhancement of the release reaction. In view of the demonstrated simultaneous release of 14 C-serotonin and 3 H-arachidonic acid metabolites, it appeared that either release of 14 C and 3 H occurs concurrently or, even if one of these events is dependent on the other, both events take place in rapid succession. Timed sequential studies revealed that in the presence of arachidonic acid, the addition of heparin hastened the apparently simultaneous release of both 14 C and 3 H

  9. Long-term kinetics of Salmonella Typhimurium ATCC 14028 survival on peanuts and peanut confectionery products.

    Directory of Open Access Journals (Sweden)

    Maristela S Nascimento

    Full Text Available Due to recent large outbreaks, peanuts have been considered a product of potential risk for Salmonella. Usually, peanut products show a low water activity (aw and high fat content, which contribute to increasing the thermal resistance and survival of Salmonella. This study evaluated the long-term kinetics of Salmonella survival on different peanut products under storage at 28°C for 420 days. Samples of raw in-shell peanuts (aw = 0.29, roasted peanuts (aw = 0.39, unblanched peanut kernel (aw = 0.54, peanut brittle (aw = 0.30, paçoca (aw = 0.40 and pé-de-moça (aw = 0.68 were inoculated with Salmonella Typhimurium ATCC 14028 at two inoculum levels (3 and 6 log cfu/ g. The Salmonella behavior was influenced (p420 days, especially in products with aw around 0.40.

  10. Suppression of grasshopper sound production by nitric oxide-releasing neurons of the central complex

    Science.gov (United States)

    Weinrich, Anja; Kunst, Michael; Wirmer, Andrea; Holstein, Gay R.

    2008-01-01

    The central complex of acridid grasshoppers integrates sensory information pertinent to reproduction-related acoustic communication. Activation of nitric oxide (NO)/cyclic GMP-signaling by injection of NO donors into the central complex of restrained Chorthippus biguttulus females suppresses muscarine-stimulated sound production. In contrast, sound production is released by aminoguanidine (AG)-mediated inhibition of nitric oxide synthase (NOS) in the central body, suggesting a basal release of NO that suppresses singing in this situation. Using anti-citrulline immunocytochemistry to detect recent NO production, subtypes of columnar neurons with somata located in the pars intercerebralis and tangential neurons with somata in the ventro-median protocerebrum were distinctly labeled. Their arborizations in the central body upper division overlap with expression patterns for NOS and with the site of injection where NO donors suppress sound production. Systemic application of AG increases the responsiveness of unrestrained females to male calling songs. Identical treatment with the NOS inhibitor that increased male song-stimulated sound production in females induced a marked reduction of citrulline accumulation in central complex columnar and tangential neurons. We conclude that behavioral situations that are unfavorable for sound production (like being restrained) activate NOS-expressing central body neurons to release NO and elevate the behavioral threshold for sound production in female grasshoppers. PMID:18574586

  11. Ruminal degradation kinetics of protein foods by in vitro gas production technique

    Directory of Open Access Journals (Sweden)

    Ivone Yurika Mizubuti

    2014-02-01

    Full Text Available Chemical analysis of carbohydrates and nitrogen fractions, as well as, determination their carbohydrates digestion rates in soyben meal (SM, crambe meal (CM, radish meal (RM, wet brewery residue (WBR and dehydrated silkworm chrysalis (SCD were accomplished. The kinetics parameters of non-fibrous carbohydrates (NFC and B2 fraction were estimated using cumulative gas production technique. Among the foods studied there was considerable variation in chemical composition. The crambe meal was the only food that did not present synchronism between carbohydrate and nitrogen fractions. In this food there was predominance of A+B1 carbohydrates fractions and B1+B2 nitrogen compounds fraction, and for the other predominated B2 carbohydrate fraction and B1+ B2 nitrogen compounds fraction. There were differences among the digestive kinetic parameters for all foods. The greater participation in gas production due to non-fibrous carbohydrates was found in the crambe meal and oilseed radish meal. The fermentation of fibrous carbohydrates provided higher gas volume in the wet brewery residue and in the soybean meal, however, the soybean meal was food with higher total gas volume. Non fibrous carbohydrates degradation rates of wet brewery residue and dehydrated silkworm chrysalis were far below the limits of degradation of this fraction. Due to the parameters obtained by the cumulative gas production, the soybean meal was the best food, however, all others have potential for use in animal nutrition. The cumulative gas production technique allows the estimative of degradation rates and provides further information about the ruminal fermentation kinetics of foods.

  12. Production of lactic acid from sucrose: strain selection, fermentation, and kinetic modeling.

    Science.gov (United States)

    Lunelli, Betânia H; Andrade, Rafael R; Atala, Daniel I P; Wolf Maciel, Maria Regina; Maugeri Filho, Francisco; Maciel Filho, Rubens

    2010-05-01

    Lactic acid is an important product arising from the anaerobic fermentation of sugars. It is used in the pharmaceutical, cosmetic, chemical, and food industries as well as for biodegradable polymer and green solvent production. In this work, several bacterial strains were isolated from industrial ethanol fermentation, and the most efficient strain for lactic acid production was selected. The fermentation was conducted in a batch system under anaerobic conditions for 50 h at a temperature of 34 degrees C, a pH value of 5.0, and an initial sucrose concentration of 12 g/L using diluted sugarcane molasses. Throughout the process, pulses of molasses were added in order to avoid the cell growth inhibition due to high sugar concentration as well as increased lactic acid concentrations. At the end of the fermentation, about 90% of sucrose was consumed to produce lactic acid and cells. A kinetic model has been developed to simulate the batch lactic acid fermentation results. The data obtained from the fermentation were used for determining the kinetic parameters of the model. The developed model for lactic acid production, growth cell, and sugar consumption simulates the experimental data well.

  13. Oxidation of trimethoprim by ferrate(VI): kinetics, products, and antibacterial activity.

    Science.gov (United States)

    Anquandah, George A K; Sharma, Virender K; Knight, D Andrew; Batchu, Sudha Rani; Gardinali, Piero R

    2011-12-15

    Kinetics, stoichiometry, and products of the oxidation of trimethoprim (TMP), one of the most commonly detected antibacterial agents in surface waters and municipal wastewaters, by ferrate(VI) (Fe(VI)) were determined. The pH dependent second-order rate constants of the reactions of Fe(VI) with TMP were examined using acid-base properties of Fe(VI) and TMP. The kinetics of reactions of diaminopyrimidine (DAP) and trimethoxytoluene (TMT) with Fe(VI) were also determined to understand the reactivity of Fe(VI) with TMP. Oxidation products of the reactions of Fe(VI) with TMP and DAP were identified by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Reaction pathways of oxidation of TMP by Fe(VI) are proposed to demonstrate the cleavage of the TMP molecule to ultimately result in 3,4,5,-trimethoxybenzaldehyde and 2,4-dinitropyrimidine as among the final identified products. The oxidized products mixture exhibited no antibacterial activity against E. coli after complete consumption of TMP. Removal of TMP in the secondary effluent by Fe(VI) was achieved.

  14. Calculation of the Fission Product Release for the HTR-10 based on its Operation History

    International Nuclear Information System (INIS)

    Xhonneux, A.; Druska, C.; Struth, S.; Allelein, H.-J.

    2014-01-01

    Since the first criticality of the HTR-10 test reactor in 2000, a rather complex operation history was performed. As the HTR-10 is the only pebble bed reactor in operation today delivering experimental data for HTR simulation codes, an attempt was made to simulate the whole reactor operation up to the presence. Special emphasis was put on the fission product release behaviour as it is an important safety aspect of such a reactor. The operation history has to be simulated with respect to the neutronics, fluid mechanics and depletion to get a detailed knowledge about the time-dependent nuclide inventory. In this paper we report about such a simulation with VSOP 99/11 and our new fission product release code STACY. While STACY (Source Term Analysis Code System) so far was able to calculate the fission product release rates in case of an equilibrium core and during transients, it now can also be applied to running-in-phases. This coupling demonstrates a first step towards an HCP Prototype. Based on the published power histogram of the HTR-10 and additional information about the fuel loading and shuffling, a coupled neutronics, fluid dynamics and depletion calculation was performed. Special emphasis was put on the complex fuel-shuffling scheme within both VSOP and STACY. The simulations have shown that the HTR-10 up to now generated about 2580 MWd while reshuffling the core about 2.3 times. Within this paper, STACY results for the equilibrium core will be compared with FRESCO-II results being published by INET. Compared to these release rates, which are based on a few user defined life histories, in this new approach the fission product release rates of Ag-110m, Cs-137, Sr-90 and I-131 have been simulated for about 4000 tracer pebbles with STACY. For the calculation of the HTR-10 operation history time-dependent release rates are being presented as well. (author)

  15. Release of Virus from Lymphoid Tissue Affects Human Immunodeficiency Virus Type 1 and Hepatitis C Virus Kinetics in the Blood

    NARCIS (Netherlands)

    Müller, Viktor; Marée, Athanasius F.M.; Boer, R.J. de

    2000-01-01

    Kinetic parameters of human immunodeficiency virus type 1 (HIV-1) and hepatitis C virus (HCV) infections have been estimated from plasma virus levels following perturbation of the chronically infected (quasi-) steady state. We extend previous models by also considering the large pool of virus

  16. The release code package REVOLS/RENONS for fission product release from a liquid sodium pool into an inert gas atmosphere

    International Nuclear Information System (INIS)

    Starflinger, J.; Scholtyssek, W.; Unger, H.

    1994-12-01

    For aerosol source term considerations in the field of nuclear safety, the investigation of the release of volatile and non-volatile species from liquid surfaces into a gas atmosphere is important. In case of a hypothetical liquid metal fast breeder reactor accident with tank failure, primary coolant sodium with suspended or solved fuel particles and fission products may be released into the containment. The computer code package REVOLS/RENONS, based on a theoretical mechanistic model with a modular structure, has been developed for the prediction of sodium release as well as volatile and non-volatile radionuclide release from a liquid pool surface into the inert gas atmosphere of the inner containment. Hereby the release of sodium and volatile fission products, like cesium and sodium iodide, is calculated using a theoretical model in a mass transfer coefficient formulation. This model has been transposed into the code version REVOLS.MOD1.1, which is discussed here. It enables parameter analysis under highly variable user-defined boundary conditions. Whereas the evaporative release of the volatile components is governed by diffusive and convective transport processes, the release of the non-volatile ones may be governed by mechanical processes which lead to droplet entrainment from the wavy pool surface under conditions of natural or forced convection into the atmosphere. The mechanistic model calculates the liquid entrainment rate of the non-volatile species, like the fission product strontium oxide and the fuel (uranium dioxide) from a liquid pool surface into a parallel gas flow. The mechanistic model has been transposed into the computer code package REVOLS/RENONS, which is discussed here. Hereby the module REVOLS (RElease of VOLatile Species) calculates the evaporative release of the volatile species, while the module RENONS (RElease of NON-Volatile Species) computes the entrainment release of the non-volatile radionuclides. (orig./HP) [de

  17. Reduction of radiocesium transfer to animal products using sustained release boli with ammoniumiron(3)-Hexacyanoferrate(2)

    International Nuclear Information System (INIS)

    Hove, K.; Hansen, H.S.

    1993-01-01

    A sustained release boulus with the cesium binder ammoniumiron(III) - hexacyanoferrate (AFCF) has been developed as a countermeasure for small ruminants grazing pastures contaminated by radiocesium ( 134 Cs+ 137 Cs). The boli (40-50 g) are produced by compression of a mixture of AFCF, barite and wax. The release of AFCF from boli labelled with 137Cs-iron-hexacyanoferrate complex was studied in laboratory sheep. The release rate followed first order kinetics during the 108 d of observation and decreased from 40 to 22, 110 to 35 and 280 to 25 mg d -1 in sheep treated with 1, 2 or 3 boli respectively. The efficiency of boli in reducing radiocesium transfer to meat and milk was tested in laboratory studies with goats fed 134 Cs tracer. Until 40 d after treatment the transfer of radiocesium to milk was reduced by 35%, 60% and 85% in goats given 1, 2 og 3 boli, respectively. The reduction in radiocaesium transfer persisted for 90 d but with a lower efficiency. A similar relationship was found between number of boli and the reduction in radiocesium transfer to meat with an observed maximal reduction of 60%. (au) (20 refs.)

  18. Reduction of radiocesium transfer to animal products using sustained release boli with ammoniumiron(3)-Hexacyanoferrate(2)

    Energy Technology Data Exchange (ETDEWEB)

    Hove, K; Hansen, H S [Department of Animal Science, Agricultural University of Norway, Aas (Norway)

    1993-01-01

    A sustained release boulus with the cesium binder ammoniumiron(III) - hexacyanoferrate (AFCF) has been developed as a countermeasure for small ruminants grazing pastures contaminated by radiocesium ([sup 134]Cs+[sup 137]Cs). The boli (40-50 g) are produced by compression of a mixture of AFCF, barite and wax. The release of AFCF from boli labelled with 137Cs-iron-hexacyanoferrate complex was studied in laboratory sheep. The release rate followed first order kinetics during the 108 d of observation and decreased from 40 to 22, 110 to 35 and 280 to 25 mg d[sup -1] in sheep treated with 1, 2 or 3 boli respectively. The efficiency of boli in reducing radiocesium transfer to meat and milk was tested in laboratory studies with goats fed [sup 134]Cs tracer. Until 40 d after treatment the transfer of radiocesium to milk was reduced by 35%, 60% and 85% in goats given 1, 2 og 3 boli, respectively. The reduction in radiocaesium transfer persisted for 90 d but with a lower efficiency. A similar relationship was found between number of boli and the reduction in radiocesium transfer to meat with an observed maximal reduction of 60%. (au) (20 refs.).

  19. The Sustainable Release of Vancomycin and Its Degradation Products From Nanostructured Collagen/Hydroxyapatite Composite Layers

    Czech Academy of Sciences Publication Activity Database

    Suchý, Tomáš; Šupová, Monika; Klapková, E.; Horný, L.; Rýglová, Šárka; Žaloudková, Margit; Braun, Martin; Sucharda, Zbyněk; Ballay, R.; Veselý, J.; Chlup, H.; Denk, František

    2016-01-01

    Roč. 105, č. 3 (2016), 1288-1294 ISSN 0022-3549 R&D Projects: GA TA ČR(CZ) TA04010330 Institutional support: RVO:67985891 Keywords : anti-infectives * HPLC * coating * controlled release * degradation products * drug delivery systems * nanoparticles * pharmacokinetics * polymeric drug delivery systems Subject RIV: JI - Composite Materials Impact factor: 2.713, year: 2016

  20. Comparison of Dust Release from Epoxy and Paint Nanocomposites and Conventional Products during Sanding and Sawing

    DEFF Research Database (Denmark)

    Gomez, V.; Levin, Marcus; Saber, A. T.

    2014-01-01

    The release of dust generated during sanding or sawing of nanocomposites was compared with conventional products without nanomaterials. Epoxy-based polymers with and without carbon nanotubes, and paints with different amounts of nano-sized titanium dioxide, were machined in a closed aerosol chamber...

  1. Release and transport of fission product cesium in the TMI-2 accident

    International Nuclear Information System (INIS)

    Lorenz, R.A.; Collins, J.L.

    1986-01-01

    Approximately 50% of the fission product cesium was released from the overheated UO 2 fuel in the TMI-2 accident. Steam that boiled away from a water pool in the bottom of the reactor vessel transported the released fission products throughout the reactor coolant system (RCS). Some fission products passed directly through a leaking valve with steam and water into the containment structure, but most deposited on dry surfaces inside of the RCS before being dissolved or resuspended when the RCS was refilled with water. A cesium transport model was developed that extended measured cesium in the RCS back to the first day of the accident. The model revealed that ∼62% of the released 137 Cs deposited on dry surfaces inside of the RCS before being slowly leached and transported out of the RCS in leaked or letdown water. The leach rates from the model agreed reasonably well with those measured in the laboratory. The chemical behavior of cesium in the TMI-2 accident agreed with that observed in fission product release tests at Oak Ridge National Laboratory (ORNL)

  2. Use of ELOCA.Mk5 to calculate transient fission product release from CANDU fuel elements

    International Nuclear Information System (INIS)

    Walker, J.R.; de Vaal, J.W.; Arimescu, V.I.; McGrady, T.G.; Wong, C.

    1992-04-01

    A change in fuel element power output, or a change in heat transfer conditions, will result in an immediate change in the temperature distribution in a fuel element. The temperature distribution change will be accompanied by concomitant changes in fuel stress distribution that lead, in turn, to a release of fission products to the fuel-to-sheath gap. It is important to know the inventory of fission products in the fuel-to-sheath gap, because this inventory is a major component of the source term for many postulated reactor accidents. ELOCA.Mk5 is a FORTRAN-77 computer code that has been developed to estimate transient releases to the fuel-to-sheath gap in CANDU reactors. ELOCA.Mk5 is an integration of the FREEDOM fission product release model into the ELOCA fuel element thermo-mechanical code. The integration of FREEDOM into ELOCA allows ELOCA.Mk5 to model the feedback mechanisms between the fission product release and the thermo-mechanical response of the fuel element. This paper describes the physical model, gives details of the ELOCA.Mkt code, and describes the validation of the model. We demonstrate that the model gives good agreement with experimental results for both steady state and transient conditions

  3. Biological effects of activation products and other chemicals released from fusion power plants

    International Nuclear Information System (INIS)

    Strand, J.A.; Poston, T.M.

    1976-09-01

    Literature reviews indicate that existing information is incomplete, often contradictory, and of questionable value for the prediction and assessment of ultimate impact from fusion-associated activation products and other chemical releases. It is still uncertain which structural materials will be used in the blanket and first wall of fusion power plants. However, niobium, vanadium, vanadium-chromium alloy, vanadium-titanium alloy, sintered aluminum product, and stainless steel have been suggested. The activation products of principal concern will be the longer-lived isotopes of 26 Al, 49 V, 51 Cr, 54 Mn, 55 Fe, 58 Co, 60 Co, 93 Nb, and 94 Nb. Lithium released to the environment either during the mining cycle, from power plant operation or accident, may be in the form of a number of compound types varying in solubility and affinity for biological organisms. The effects of a severe liquid metal fire or explosion involving Na or K will vary according to inherent abiotic and biotic features of the affected site. Saline, saline-alkaline, and sodic soils of arid lands would be particularly susceptible to alkaline stress. Beryllium released to the environment during the mining cycle or reactor accident situation could be in the form of a number of compound types. Adverse effects to aquatic species from routine chemical releases (biocides, corrosion inhibitors, dissolution products) may occur in the discharge of both fission and fusion power plant designs

  4. Metabolic and Kinetic analyses of influenza production in perfusion HEK293 cell culture

    Directory of Open Access Journals (Sweden)

    Lohr Verena

    2011-09-01

    Full Text Available Abstract Background Cell culture-based production of influenza vaccine remains an attractive alternative to egg-based production. Short response time and high production yields are the key success factors for the broader adoption of cell culture technology for industrial manufacturing of pandemic and seasonal influenza vaccines. Recently, HEK293SF cells have been successfully used to produce influenza viruses, achieving hemagglutinin (HA and infectious viral particle (IVP titers in the highest ranges reported to date. In the same study, it was suggested that beyond 4 × 106 cells/mL, viral production was limited by a lack of nutrients or an accumulation of toxic products. Results To further improve viral titers at high cell densities, perfusion culture mode was evaluated. Productivities of both perfusion and batch culture modes were compared at an infection cell density of 6 × 106 cells/mL. The metabolism, including glycolysis, glutaminolysis and amino acids utilization as well as physiological indicators such as viability and apoptosis were extensively documented for the two modes of culture before and after viral infection to identify potential metabolic limitations. A 3 L bioreactor with a perfusion rate of 0.5 vol/day allowed us to reach maximal titers of 3.3 × 1011 IVP/mL and 4.0 logHA units/mL, corresponding to a total production of 1.0 × 1015 IVP and 7.8 logHA units after 3 days post-infection. Overall, perfusion mode titers were higher by almost one order of magnitude over the batch culture mode of production. This improvement was associated with an activation of the cell metabolism as seen by a 1.5-fold and 4-fold higher consumption rates of glucose and glutamine respectively. A shift in the viral production kinetics was also observed leading to an accumulation of more viable cells with a higher specific production and causing an increase in the total volumetric production of infectious influenza particles. Conclusions These results

  5. Quantification of Kinetic Rate Law Parameters of Uranium Release from Sodium Autunite as a Function of Aqueous Bicarbonate Concentrations

    Energy Technology Data Exchange (ETDEWEB)

    Gudavalli, Ravi; Katsenovich, Yelena; Wellman, Dawn M.; Lagos, Leonel; Tansel, Berrin

    2013-09-05

    ABSTRACT: Hydrogen carbonate is one of the most significant components within the uranium geochemical cycle. In aqueous solutions, hydrogen carbonate forms strong complexes with uranium. As such, aqueous bicarbonate may significantly increase the rate of uranium release from uranium minerals. Quantifying the relationship of aqueous hydrogen carbonate solutions to the rate of uranium release during dissolution is critical to understanding the long-term fate of uranium within the environment. Single-pass flow-through (SPTF) experiments were conducted to estimate the rate of uranium release from Na meta-autunite as a function of bicarbonate solutions (0.0005-0.003 M) under the pH range of 6-11 and temperatures of 5-60oC. Consistent with the results of previous investigation, the rate of uranium release from sodium autunite exhibited minimal dependency on temperature; but were strongly dependent on pH and increasing concentrations of bicarbonate solutions. Most notably at pH 7, the rate of uranium release exhibited 370 fold increases relative to the rate of uranium release in the absence of bicarbonate. However, the effect of increasing concentrations of bicarbonate solutions on the release of uranium was significantly less under higher pH conditions. It is postulated that at high pH values, surface sites are saturated with carbonate, thus the addition of more bicarbonate would have less effect on uranium release. Results indicate the activation energies were unaffected by temperature and bicarbonate concentration variations, but were strongly dependent on pH conditions. As pH increased from 6 to 11, activation energy values were observed to decrease from 29.94 kJ mol-1 to 13.07 kJ mol-1. The calculated activation energies suggest a surface controlled dissolution mechanism.

  6. LOFC fission product release and circulating activity calculations for gas-cooled reactors

    International Nuclear Information System (INIS)

    Apperson, C.E. Jr.; Carruthers, L.M.; Lee, C.E.

    1977-01-01

    The inventories of fission products in a gas-cooled reactor under accident and normal steady state conditions are time and temperature dependent. To obtain a reasonable estimate of these inventories it is necessary to consider fuel failure, a temperature dependent variable, and radioactive decay, a time dependent variable. Using arbitrary radioactive decay chains and published fuel failure models for the High Temperature Gas-Cooled Reactor (HTGR), methods have been developed to evaluate the release of fission products during the Loss of Forced Circulation (LOFC) accident and the circulating and plateout fission product inventories during steady state non-accident operation. The LARC-2 model presented here neglects the time delays in the release from the HTGR due to diffusion of fission products from particles in the fuel rod through the graphite matrix. It also neglects the adsorption and evaporation process of metallics at the fuel rod-graphite and graphite-coolant hole interfaces. Any time delay due to the finite time of transport of fission products by convection through the coolant to the outside of the prestressed concrete reactor vessel (PCRV) is also neglected. This model assumes that all fission products released from fuel particles are immediately deposited outside the PCRV with no time delay

  7. Influence of lactose addition to gentamicin-loaded acrylic bone cement on the kinetics of release of the antibiotic and the cement properties.

    Science.gov (United States)

    Frutos, Gloria; Pastor, José Ygnacio; Martínez, Noelia; Virto, María Rosa; Torrado, Susana

    2010-03-01

    The purpose of this study was to characterize a poly(methyl methacrylate) bone cement that was loaded with the antibiotic gentamicin sulphate (GS) and lactose, which served to modulate the release of GS from cement specimens. The release of GS when the cement specimens were immersed in phosphate-buffered saline at 37 degrees Celsius was determined spectrophotometrically. The microstructure, porosity, density, tensile properties and flexural properties of the cements were determined before and after release of GS. A kinetics model of the release of GS from the cement that involved a coupled mechanism based on dissolution/diffusion processes and an initial burst effect was proposed. Dissolution assay results showed that drug elution was controlled by a diffusion mechanism which can be modulated by lactose addition. Density values and mechanical properties (tensile strength, flexural strength, elastic modulus and fracture toughness) were reduced by the increased porosity resulting from lactose addition, but maintained acceptable values for the structural functions of bone cement. The present results suggest that lactose-modified, gentamicin-loaded acrylic bone cements are potential candidates for use in various orthopaedic and dental applications. Copyright 2009 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  8. Environmental contamination from a ground-level release of fission products

    International Nuclear Information System (INIS)

    Stupka, R.C.; Kephart, G.S.; Rittmann, P.D.

    1986-08-01

    On January 11, 1985, a ground-level release of fission products, primarily 90 Sr, occurred at the Hanford Site in southeastern Washington State. The release was detected during routine surveys and the majority of the contamination was confined to the immediate area where the release occurred. Response to the incident was complicated by a strong inversion that resulted in a buildup of 222 Rn daughter products on environmental air samples and outdoor surfaces. The cause of the release appears to have been the operation of a transfer jet that inadvertently pressurized an unblanked line leading to the 241-C-151 Diversion Box. A buildup of pressure inside the diversion box forced contaminated air through gaps in the diversion box cover blocks resulting in an unmonitored, short duration release to the environment. The source term was estimated using data obtained from environmental air samplers. The ground deposition speed was calculated using the integrated exposure (air samples) and surface contamination levels obtained from recently fallen snow. The total release was estimated to be 1.4 Ci 90 Sr and 0.02 Ci 137 Cs. Based on this source term, the maximum 50-yr dose commitment to onsite pesonnel was 50 mrem whole body and 600 mrem bone. No detectable internal deposition occurred during the incident and corrective action which followed; this was probably due to several factors: (1) prompt detection of the release; (2) localized contamination control; (3) excellent personnel protection practices; and (4) the protection offered by building ventilation systems. The theoretical maximum offsite individual would receive a potential 1-yr dose commitment of 0.01 mrem whole body and 0.2 mrem bone from this incident. The potential 50-yr dose commitment would be 0.13 mrem whole body and 2.0 mrem bone. In actuality, neither onsite or offsite individuals would be expected to receive even these small dose commitments

  9. Kinetics study of levulinic acid production from corncobs by tin tetrachloride as catalyst.

    Science.gov (United States)

    Qing, Qing; Guo, Qi; Wang, Pengbo; Qian, Hongjia; Gao, Xiaohang; Zhang, Yue

    2018-07-01

    Levulinic acid (LA) is an ideal platform chemical that can be produced through acid-catalyzed dehydration and hydrolysis of hexose sugars obtained from lignocellulosic materials. In this study, SnCl 4 was identified as an efficient catalyst for LA production and the reaction kinetics was investigated in a single water phase under different reaction conditions. The Box-Behnken design response surface methodology (RSM) was applied to determine the optimized reaction conditions and three individual variables including reaction temperature, duration, and catalyst concentration were evaluated. An appealing LA yield of 76.0% was achieved at 193 °C and 17 min with 82 mM SnCl 4 catalyst. A kinetics model was developed to predict the yields of glucose, HMF, and LA, which are tally with the experimental results. The analysis of the related kinetic parameters and the results of the RSM experiment helped to provide insights into the interplay between various reaction steps with SnCl 4 as catalysts. Copyright © 2018 Elsevier Ltd. All rights reserved.

  10. Photolysis of nonylphenol ethoxylates: the determination of the degradation kinetics and the intermediate products.

    Science.gov (United States)

    Chen, Ling; Zhou, Hai-Yun; Deng, Qin-Ying

    2007-06-01

    The photolysis of nonylphenol ethoxylates with an average oligomers length of ten ethoxylate units (NPEO(10)) in aqueous solution under UV, as well as the influence of humic acid (HA) on the photolysis was studied. A 125W high-pressure mercury lamp was employed as the light source. The intermediate products from the photolysis were determined by LC-MS. The results indicated that NPEO(10) underwent direct photolysis upon exposed to UV. The degradation pathway was complex. Besides the generally proposed degradation pathway of ethylene oxide (EO) side chains shortening, the oxidation of alkyl chain and EO chain led to intermediates having both a carboxylated (as well as carbonylated) ethoxylate and alkyl chain of varying lengths. The hydrogenation of benzene ring was also detected. The kinetics data showed that the first order reaction kinetics could be well used to describe the kinetics of NPEO(10) degradation. In the presence of dissolved organic matter by HA addition, the performance of NPEO(10) photodegradation was reduced. The photolysis rate decreased with increased HA concentration.

  11. Kinetics and Products of Chromium(VI) Reduction by Iron(II/III)-Bearing Clay Minerals.

    Science.gov (United States)

    Joe-Wong, Claresta; Brown, Gordon E; Maher, Kate

    2017-09-05

    Hexavalent chromium is a water-soluble pollutant, the mobility of which can be controlled by reduction of Cr(VI) to less soluble, environmentally benign Cr(III). Iron(II/III)-bearing clay minerals are widespread potential reductants of Cr(VI), but the kinetics and pathways of Cr(VI) reduction by such clay minerals are poorly understood. We reacted aqueous Cr(VI) with two abiotically reduced clay minerals: an Fe-poor montmorillonite and an Fe-rich nontronite. The effects of ionic strength, pH, total Fe content, and the fraction of reduced structural Fe(II) [Fe(II)/Fe(total)] were examined. The last variable had the largest effect on Cr(VI) reduction kinetics: for both clay minerals, the rate constant of Cr(VI) reduction varies by more than 3 orders of magnitude with Fe(II)/Fe(total) and is described by a linear free energy relationship. Under all conditions examined, Cr and Fe K-edge X-ray absorption near-edge structure spectra show that the main Cr-bearing product is a Cr(III)-hydroxide and that Fe remains in the clay structure after reacting with Cr(VI). This study helps to quantify our understanding of the kinetics of Cr(VI) reduction by Fe(II/III)-bearing clay minerals and may improve predictions of Cr(VI) behavior in subsurface environments.

  12. Biohydrogen Production and Kinetic Modeling Using Sediment Microorganisms of Pichavaram Mangroves, India

    Directory of Open Access Journals (Sweden)

    P. Mullai

    2013-01-01

    Full Text Available Mangrove sediments host rich assemblages of microorganisms, predominantly mixed bacterial cultures, which can be efficiently used for biohydrogen production through anaerobic dark fermentation. The influence of process parameters such as effect of initial glucose concentration, initial medium pH, and trace metal (Fe2+ concentration was investigated in this study. A maximum hydrogen yield of 2.34, 2.3, and 2.6 mol H2 mol−1 glucose, respectively, was obtained under the following set of optimal conditions: initial substrate concentration—10,000 mg L−1, initial pH—6.0, and ferrous sulphate concentration—100 mg L−1, respectively. The addition of trace metal to the medium (100 mg L−1 FeSO4·7H2O enhanced the biohydrogen yield from 2.3 mol H2 mol−1 glucose to 2.6 mol H2 mol−1 glucose. Furthermore, the experimental data was subjected to kinetic analysis and the kinetic constants were estimated with the help of well-known kinetic models available in the literature, namely, Monod model, logistic model and Luedeking-Piret model. The model fitting was found to be in good agreement with the experimental observations, for all the models, with regression coefficient values >0.92.

  13. An new MHD/kinetic model for exploring energetic particle production in macro-scale systems

    Science.gov (United States)

    Drake, J. F.; Swisdak, M.; Dahlin, J. T.

    2017-12-01

    A novel MHD/kinetic model is being developed to explore magneticreconnection and particle energization in macro-scale systems such asthe solar corona and the outer heliosphere. The model blends the MHDdescription with a macro-particle description. The rationale for thismodel is based on the recent discovery that energetic particleproduction during magnetic reconnection is controlled by Fermireflection and Betatron acceleration and not parallel electricfields. Since the former mechanisms are not dependent on kineticscales such as the Debye length and the electron and ion inertialscales, a model that sheds these scales is sufficient for describingparticle acceleration in macro-systems. Our MHD/kinetic model includesmacroparticles laid out on an MHD grid that are evolved with the MHDfields. Crucially, the feedback of the energetic component on the MHDfluid is included in the dynamics. Thus, energy of the total system,the MHD fluid plus the energetic component, is conserved. The systemhas no kinetic scales and therefore can be implemented to modelenergetic particle production in macro-systems with none of theconstraints associated with a PIC model. Tests of the new model insimple geometries will be presented and potential applications will bediscussed.

  14. Optimization and kinetic studies of sea mango (Cerbera odollam) oil for biodiesel production via supercritical reaction

    International Nuclear Information System (INIS)

    Ang, Gaik Tin; Ooi, San Nee; Tan, Kok Tat; Lee, Keat Teong; Mohamed, Abdul Rahman

    2015-01-01

    Highlights: • Sea mango oil as feedstock for biodiesel via non-catalytic supercritical reaction. • Extracted sea mango oil with high FFA could produce high yield of FAME. • Employment of Response Surface Methodology for optimization of FAME. • Kinetic study for reversible transesterification and esterification reactions. - Abstract: Sea mango (Cerbera odollam) oil, which is rich in free fatty acids, was utilized to produce fatty acid methyl esters (FAME) via supercritical transesterification reaction. Sea mango oil was extracted from seeds and was subsequently reacted with methanol in a batch-type supercritical reactor. Response surface methodology (RSM) analysis was used to optimize important parameters, including reaction temperature, reaction time and the molar ratio of methanol to oil. The optimum conditions were found as 380 °C, 40 min and 45:1 mol/mol, respectively, to achieve 78% biodiesel content. The first kinetic modelling of FAME production from sea mango oil incorporating reversible transesterification and reversible esterification was verified simultaneously. The kinetic parameters, including reaction rate constants, k, the pre-exponential constant, A, and the activation energy, Ea, for transesterification and esterification were determined using an ordinary differential equation (ODE45) solver. The highest activation energy of 40 kJ/mol and the lowest reaction rate constant of 2.50 × 10 −5 dm 3 /mol s verified that the first stepwise reaction of TG to produce DG was the rate-limiting step

  15. Electro-oxidation of the dye azure B: kinetics, mechanism, and by-products.

    Science.gov (United States)

    Olvera-Vargas, Hugo; Oturan, Nihal; Aravindakumar, C T; Paul, M M Sunil; Sharma, Virender K; Oturan, Mehmet A

    2014-01-01

    In this work, the electrochemical degradation of the dye azure B in aqueous solutions was studied by electrochemical advanced oxidation processes (EAOPs), electro-Fenton, and anodic oxidation processes, using Pt/carbon-felt and boron-doped diamond (BDD)/carbon-felt cells with H₂O₂ electrogeneration. The higher oxidation power of the electro-Fenton (EF) process using BDD anode was demonstrated. The oxidative degradation of azure B by the electrochemically generated hydroxyl radicals ((•)OH) follows a pseudo-first-order kinetics. The apparent rate constants of the oxidation of azure B by (•)OH were measured according to pseudo-first-order kinetic model. The absolute rate constant of azure B hydroxylation reaction was determined by competition kinetics method and found to be 1.19 × 10(9) M(-1) s(-1). It was found that the electrochemical degradation of the dye leads to the formation of aromatic by-products which are then oxidized to aliphatic carboxylic acids before their almost mineralization to CO₂ and inorganic ions (sulfate, nitrate, and ammonium). The evolution of the TOC removal and time course of short-chain carboxylic acids during treatment were also investigated.

  16. Scientific and Regulatory Considerations in Solid Oral Modified Release Drug Product Development.

    Science.gov (United States)

    Li, Min; Sander, Sanna; Duan, John; Rosencrance, Susan; Miksinski, Sarah Pope; Yu, Lawrence; Seo, Paul; Rege, Bhagwant

    2016-11-01

    This review presents scientific and regulatory considerations for the development of solid oral modified release (MR) drug products. It includes a rationale for patient-focused development based on Quality-by-Design (QbD) principles. Product and process understanding of MR products includes identification and risk-based evaluation of critical material attributes (CMAs), critical process parameters (CPPs), and their impact on critical quality attributes (CQAs) that affect the clinical performance. The use of various biopharmaceutics tools that link the CQAs to a predictable and reproducible clinical performance for patient benefit is emphasized. Product and process understanding lead to a more comprehensive control strategy that can maintain product quality through the shelf life and the lifecycle of the drug product. The overall goal is to develop MR products that consistently meet the clinical objectives while mitigating the risks to patients by reducing the probability and increasing the detectability of CQA failures.

  17. Release of Phosphorus Forms from Cover Crop Residues in Agroecological No-Till Onion Production

    Directory of Open Access Journals (Sweden)

    Rodolfo Assis de Oliveira

    Full Text Available ABSTRACT Cover crops grown alone or in association can take up different amounts of phosphorus (P from the soil and accumulate it in different P-forms in plant tissue. Cover crop residues with a higher content of readily decomposed forms may release P more quickly for the next onion crop. The aim of this study was to evaluate the release of P forms from residues of single and mixed cover crops in agroecological no-till onion (Allium cepa L. production. The experiment was conducted in Ituporanga, Santa Catarina (SC, Brazil, in an Inceptisol, with the following treatments: weeds, black oat (Avena sativa L., rye (Secale cereale L., oilseed radish (Raphanus sativus L., oilseed radish + black oat, and oilseed radish + rye. Cover crops were sown in April 2013. In July 2013, plant shoots were cut close to the soil surface and part of the material was placed in litterbags. The bags were placed on the soil surface and residues were collected at 0, 15, and 45 days after deposition (DAD. Residues were dried and ground and P in the plant tissue was determined through chemical fractionation. The release of P contained in the tissue of cover crops depends not only on total P content in the tissue, but also on the accumulation of P forms and the quality of the residue in decomposition. The highest accumulation of P in cover crops occurred in the soluble inorganic P fraction, which is the fraction of fastest release in plants. Black oat had the highest initial release rate of soluble inorganic P, which became equal to the release rate of other cover crop residues at 45 DAD. Weeds released only half the amount of soluble inorganic P in the same period, despite accumulating a considerable amount of P in their biomass. The mixtures of oilseed radish + rye and oilseed radish + black oat showed higher release of P associated with RNA at 45 DAD in comparison to the single treatments.

  18. Kinetics of ethanol production from Jerusalem artichoke juice with some Kluyveromyces species

    Energy Technology Data Exchange (ETDEWEB)

    Kuvnjak, Z.; Kosaric, N.; Hayes, R.D.

    1981-01-01

    The kinetics of ethanol production by Kluyveromyces marxianus ATCC 12708 and ATCC 10606, K. cicerisporus ATCC 22295 and K. fragilis 105 were studied using raw juice of the Jerusalem artichoke in which the carbohydrates were not hydrolyzed prior to fermentation. This juice contains enough nutrients and can serve as a complete medium without additional nutrients both for growth of the yeasts and for ethanol production. Both specific ethanol productivity and specific glucose uptake rates were the highest with K. marxianus ATCC 12708 (1.68 gg-1 h-1 and 3.78 gg-1h-1, respectively). This microorganism produced an ethanol yield of 87.5% of the theoretical value in 25 hours.

  19. Impact of pre-equilibration and diffusion limited release kinetics on effluent concentration in column leaching tests: Insights from numerical simulations.

    Science.gov (United States)

    Finkel, Michael; Grathwohl, Peter

    2017-05-01

    Column leaching tests have become a standard method for assessing leaching of pollutants from materials used, e.g., for road and railway constructions and in landscaping measures. Column tests showed to be practical in laboratories yielding robust and reproducible results. However, considerable uncertainty still exists related particularly to the degree of equilibration of the pore water with the solids during preparation (pre-equilibration) and percolation of the column. We analyse equilibration time scales and sensitivity of concentrations in column leachate with respect to initial conditions in a series of numerical experiments covering a broad spectrum of material and solute properties. Slow release of pollutants from solid materials is described by a spherical diffusion model of kinetic sorption accounting for multiple grain size fractions and sorption capacities. Results show that the cumulative concentrations are rather independent of the pre-equilibration level for a broad spectrum of parameter settings, e.g. if intra-particle porosity is high, grain size is small, or if the sorption coefficient is large. Sensitivity increases with decreasing liquid solid ratios and contact time during percolation. Significant variations with initial column conditions are to be expected for material and compound properties leading to slow release kinetics. In these cases, sensitivity to initial conditions may have to be considered. Copyright © 2016 Elsevier Ltd. All rights reserved.

  20. Kinetic modeling of simultaneous saccharification and fermentation of corn starch for ethanol production.

    Science.gov (United States)

    Białas, Wojciech; Czerniak, Adrian; Szymanowska-Powałowska, Daria

    2014-01-01

    Fuel ethanol production, using a simultaneous saccharification and fermentation process (SSF) of native starch from corn flour, has been performed using Saccharomyces cerevisiae and a granular starch hydrolyzing enzyme. The quantitative effects of mash concentration, enzyme dose and pH were investigated with the use of a Box-Wilson central composite design protocol. Proceeding from results obtained in optimal fermentation conditions, a kinetics model relating the utilization rates of starch and glucose as well as the production rates of ethanol and biomass was tested. Moreover, scanning electron microscopy (SEM) was applied to investigate corn starch granule surface after the SFF process. A maximum ethanol concentration of 110.36 g/l was obtained for native corn starch using a mash concentration of 25%, which resulted in ethanol yield of 85.71%. The optimal conditions for the above yield were found with an enzyme dose of 2.05 ml/kg and pH of 5.0. These results indicate that by using a central composite design, it is possible to determine optimal values of the fermentation parameters for maximum ethanol production. The investigated kinetics model can be used to describe SSF process conducted with granular starch hydrolyzing enzymes. The SEM micrographs reveal randomly distributed holes on the surface of granules.

  1. Is automated kinetic measurement superior to end-point for advanced oxidation protein product?

    Science.gov (United States)

    Oguz, Osman; Inal, Berrin Bercik; Emre, Turker; Ozcan, Oguzhan; Altunoglu, Esma; Oguz, Gokce; Topkaya, Cigdem; Guvenen, Guvenc

    2014-01-01

    Advanced oxidation protein product (AOPP) was first described as an oxidative protein marker in chronic uremic patients and measured with a semi-automatic end-point method. Subsequently, the kinetic method was introduced for AOPP assay. We aimed to compare these two methods by adapting them to a chemistry analyzer and to investigate the correlation between AOPP and fibrinogen, the key molecule responsible for human plasma AOPP reactivity, microalbumin, and HbA1c in patients with type II diabetes mellitus (DM II). The effects of EDTA and citrate-anticogulated tubes on these two methods were incorporated into the study. This study included 93 DM II patients (36 women, 57 men) with HbA1c levels > or = 7%, who were admitted to the diabetes and nephrology clinics. The samples were collected in EDTA and in citrate-anticoagulated tubes. Both methods were adapted to a chemistry analyzer and the samples were studied in parallel. In both types of samples, we found a moderate correlation between the kinetic and the endpoint methods (r = 0.611 for citrate-anticoagulated, r = 0.636 for EDTA-anticoagulated, p = 0.0001 for both). We found a moderate correlation between fibrinogen-AOPP and microalbumin-AOPP levels only in the kinetic method (r = 0.644 and 0.520 for citrate-anticoagulated; r = 0.581 and 0.490 for EDTA-anticoagulated, p = 0.0001). We conclude that adaptation of the end-point method to automation is more difficult and it has higher between-run CV% while application of the kinetic method is easier and it may be used in oxidative stress studies.

  2. Enzyme-catalyzed synthesis and kinetics of ultrasonic-assisted biodiesel production from waste tallow.

    Science.gov (United States)

    Adewale, Peter; Dumont, Marie-Josée; Ngadi, Michael

    2015-11-01

    The use of ultrasonic processing was evaluated for its ability to achieve adequate mixing while providing sufficient activation energy for the enzymatic transesterification of waste tallow. The effects of ultrasonic parameters (amplitude, cycle and pulse) and major reaction factors (molar ratio and enzyme concentration) on the reaction kinetics of biodiesel generation from waste tallow bio-catalyzed by immobilized lipase [Candida antarctica lipase B (CALB)] were investigated. Three sets of experiments namely A, B, and C were conducted. In experiment set A, two factors (ultrasonic amplitude and cycle) were investigated at three levels; in experiment set B, two factors (molar ratio and enzyme concentration) were examined at three levels; and in experiment set C, two factors (ultrasonic amplitude and reaction time) were investigated at five levels. A Ping Pong Bi Bi kinetic model approach was employed to study the effect of ultrasonic amplitude on the enzymatic transesterification. Kinetic constants of transesterification reaction were determined at different ultrasonic amplitudes (30%, 35%, 40%, 45%, and 50%) and enzyme concentrations (4, 6, and 8 wt.% of fat) at constant molar ratio (fat:methanol); 1:6, and ultrasonic cycle; 5 Hz. Optimal conditions for ultrasound-assisted biodiesel production from waste tallow were fat:methanol molar ratio, 1:4; catalyst level 6% (w/w of fat); reaction time, 20 min (30 times less than conventional batch processes); ultrasonic amplitude 40% at 5 Hz. The kinetic model results revealed interesting features of ultrasound assisted enzyme-catalyzed transesterification (as compared to conventional system): at ultrasonic amplitude 40%, the reaction activities within the system seemed to be steady after 20 min which means the reaction could proceed with or without ultrasonic mixing. Reversed phase high performance liquid chromatography indicated the biodiesel yield to be 85.6±0.08%. Copyright © 2015 Elsevier B.V. All rights reserved.

  3. Ethanol Production from Whey by Kluyveromyces marxianus in Batch Fermentation System: Kinetics Parameters Estimation

    Directory of Open Access Journals (Sweden)

    Dessy Ariyanti

    2013-03-01

    Full Text Available Whey is the liquid remaining after milk has been curdled and strained. It is a by-product of the manufacture of cheese or casein and has several commercial uses. In environmental point of view, whey is kind of waste which has high pollution level due to it’s contain high organic compound with BOD and COD value 50 and 80 g/L respectively. On the other side, whey also contain an amount of lactose (4.5%-5%; lactose can be used as carbon source and raw material for producing ethanol via fermentation using yeast strain Kluyveromyces marxianus. The objective of this research is to investigate the ethanol production kinetics from crude whey through fermentation using Kluyveromyces marxianus and to predict the model kinetics parameter. The yeast was able to metabolize most of the lactose within 16 h to give 8.64 g/L ethanol, 4.43 g/L biomass, and remain the 3.122 g/L residual lactose. From the results presented it also can be concluded that common kinetic model for microbial growth, substrate consumption, and product formation is a good alternative to describe an experimental batch fermentation of Kluyveromyces marxianus grown on a medium composed of whey. The model was found to be capable of reflecting all batch culture phases to a certain degree of accuracy, giving the parameter value: μmax, Ks, YX/S, α, β : 0.32, 10.52, 0.095, 1.52, and 0.11 respectively. © 2013 BCREC UNDIP. All rights reserved(Selected Paper from International Conference on Chemical and Material Engineering (ICCME 2012Received: 27th September 2012; Revised: 29th November 2012; Accepted: 7th December 2012[How to Cite: D. Ariyanti, H. Hadiyanto, (2013. Ethanol Production from Whey by Kluyveromyces marxianus in Batch Fermentation System: Kinetics Parameters Estimation. Bulletin of Chemical Reaction Engineering & Catalysis, 7 (3: 179-184. (doi:10.9767/bcrec.7.3.4044.179-184][Permalink/DOI: http://dx.doi.org/10.9767/bcrec.7.3.4044.179-184 ] View in  |

  4. FY17Q4 Ristra project: Release Version 1.0 of a production toolkit

    Energy Technology Data Exchange (ETDEWEB)

    Hungerford, Aimee L. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Daniel, David John [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-09-21

    The Next Generation Code project will release Version 1.0 of a production toolkit for multi-physics application development on advanced architectures. Features of this toolkit will include remap and link utilities, control and state manager, setup, visualization and I/O, as well as support for a variety of mesh and particle data representations. Numerical physics packages that operate atop this foundational toolkit will be employed in a multi-physics demonstration problem and released to the community along with results from the demonstration.

  5. Data sheets of fission product release experiments for light water reactor fuel, (2)

    International Nuclear Information System (INIS)

    Ishiwatari, Nasumi; Nagai, Hitoshi; Takeda, Tsuneo; Yamamoto, Katsumune; Nakazaki, Chozaburo.

    1979-07-01

    This is the second data sheets of fission products (FP) release experiments for light water reactor fuel. Results of five FP release experiments from the third to the seventh are presented: results of pre-examinations of UO 2 pellets, photographs of parts of fuel rod assemblies for irradiation and the assemblies, operational conditions of JMTR and OWL-1, variations of radioiodine-131 level in the main loop coolant during experimental periods, and representative results of post-irradiation examinations of respective fuel rods. (author)

  6. Qualitative assessment of the fission product release capability of ELOCA.Mk5

    International Nuclear Information System (INIS)

    Klein, M.E.; Carlucci, L.N.; Arimescu, V.I.

    1995-01-01

    A qualitative assessment of the fission product release capability of the ELOCA.Mk5 computer code was performed by simulating two transients from the sweep-gas experiment, FIO-133. Improved agreement between calculated and experimental trends in release was obtained by applying an interface pressure stress component to the pellet center. As well, results show that the current system for defining the reference temperature distribution for the thermal stress component is not always realistic. These results are being used in the development of a new, mechanistic pellet stress model. (author)

  7. Safety aspects of targets for ADTT: Activity, volatile products, residual heat release

    International Nuclear Information System (INIS)

    Gai, E.V.; Ignatyuk, A.V.; Lunev, V.P.; Shubin, Yu.N.

    1999-01-01

    Safety aspects of heavy metal liquid targets for the accelerator driven systems connected with the activity accumulation and residual energy release due to the irradiation with high energy proton beam are discussed. The results obtained for the lead-bismuth target that are under construction in IPPE now in the frame of ISTC Project No. 559 are briefly presented. The calculations and the analysis of the accumulation of the spallation reaction products, activity and energy release at various moments after the accelerator shutdown are presented. The concentrations of the reaction products, the total and partial activities, the activities of volatile products are determined. The contributions of the short-lived nuclides important for the prediction of the facility behaviour in regimes with the accelerator beam trips. The calculations and analysis of the residual energy release due to different decay type have been performed. The conclusions are as follows. The obtained results showed that long lived radioactivity accumulates mainly due to primary nuclear reactions. Secondary reactions are responsible for the production of small number of long-lived isotopes Bi-207, Po-210 and some others, being generated by radiative capture of low energy neutrons. It is possible to make a conclusion that neutrons in the energy range 20 - 800 MeV and protons with energy above 100 MeV give main contribution to the total activity generation although these parts of spectra inside the target give comparatively small contribution to the total flux. The correct consideration of short-lived nuclides contribution is the main problem in the analysis of the target behaviour in the case of short accelerator shutdowns. They make the determining contribution to the both activity and the heat release at the first moments after the accelerator shutdown, creating the intermediate links and additional channels for the long-lived nuclides accumulation chains. The strong dependence of calculated

  8. Modeling of molten core-concrete interactions and fission-product release

    International Nuclear Information System (INIS)

    Norkus, J.K.; Corradini, M.L.

    1991-09-01

    The study of molten core-concrete interaction is important in estimating the possible consequences of a severe nuclear reactor accident. CORCON-Mod2 is a computer program which models the thermal, chemical, and physical phenomena associated with molten core-concrete interactions. Models have been added to extend and improve the modeling of these phenomena. An ideal solution chemical equilibrium methodology is presented to predict the fission-product vaporization release. Additional chemical species have been added, and the calculation of chemical equilibrium has been expanded to the oxidic layer and to the mixed layer configuration. Recent experiments performed at Argonne National Laboratory are compared to CORCON predictions of melt temperature, erosion depth, and release fraction of fission products. The results consistently underpredicted the melt temperatures and erosion rates. However, the predictions of release of Te, Ba, Sr, and U were good. A sensitivity study of the effects of initial temperature, concrete type, use of the mixing option, degree of zirconium oxidation, cavity size, and amount of control material on erosion, gas production, and release of radioactive materials was performed for a PWR and a BWR. The initial melt temperature had the greatest effect on the results of interest. Concrete type and cavity size also had important effects. 78 refs., 35 figs., 40 tabs

  9. Research on in-pile release of fission products from coated particle fuels

    International Nuclear Information System (INIS)

    Fukuda, K.; Iwamoto, K.

    1985-01-01

    Coated particle fuels fabricated in accordance with VHTR (Very High Temperature gas-cooled Reactor) fuel design have been irradiated by both capsules and an in-pile gas loop (OGL-1), and data on the fission products release under irradiation were obtained for loose coated particles, fuel compacts and fuel rods in the temperature range between 800 deg. C and 1600 deg. C. For the fission gases, temperature- and time dependences of the fractional release(R/B) were measured. Relation between release and failure fraction of the coated particles was elucidated on the VHTR reference fuels. Also measured was tritium concentration in the helium coolant of OGL-1. In-pile release behavior of the metallic fission products was studied by measuring the activities of the fission products adsorbed in the graphite sleeves of the OGL-1 fuel rods and the graphite fuel container of the sweep gas capsules in the PIE. Investigation on palladium interaction with SiC coating layer was included. (author)

  10. Future trends in the assessment of hazards from fission product releases

    Energy Technology Data Exchange (ETDEWEB)

    Beattie, J. R.

    1983-11-15

    In comparing and selecting sites for reactors from the point of view of safety, one considers the remote possibility of an accidental release of moderately large amounts of fission products and its effects in relation to the present and future distribution of population in the neighbourhood. At present, until experience is gained of the reliability and safety of reactors, there is a tendency to site them remotely from centres of industry and population, although for economic reasons there will be a need to site large power reactors more closely to such centres in the future. With, among other objectives, the aim of adopting, in the proper course or time, less restrictive siting criteria, improvements are continually made in the intrinsic safety of reactor system and more sophisticated forms of reactor containment are devised, in order to reduce the possibility and scale of any fission product release. Changes and improvements in reactor systems could affect the nature and proportion of an accidental release of fission products if this should occur in the future. It is appropriate to consider what such a release and its radiobiological effects might be.

  11. Some Investigations on Protease Enzyme Production Kinetics Using Bacillus licheniformis BBRC 100053 and Effects of Inhibitors on Protease Activity

    Directory of Open Access Journals (Sweden)

    Zahra Ghobadi Nejad

    2014-01-01

    Full Text Available Due to great commercial application of protease, it is necessary to study kinetic characterization of this enzyme in order to improve design of enzymatic reactors. In this study, mathematical modeling of protease enzyme production kinetics which is derived from Bacillus licheniformis BBRC 100053 was studied (at 37°C, pH 10 after 73 h in stationary phase, and 150 rpm. The aim of the present paper was to determine the best kinetic model and kinetic parameters for production of protease and calculating Ki (inhibition constant of different inhibitors to find the most effective one. The kinetic parameters Km (Michaelis-Menten constant and Vm (maximum rate were calculated 0.626 mM and 0.0523 mM/min. According to the experimental results, using DFP (diisopropyl fluorophosphate and PMSF (phenylmethanesulfonyl fluoride as inhibitors almost 50% of the enzyme activity could be inhibited when their concentrations were 0.525 and 0.541 mM, respectively. Ki for DFP and PMSF were 0.46 and 0.56 mM, respectively. Kinetic analysis showed that the Lineweaver-Burk model was the best fitting model for protease production kinetics DFP was more effective than PMSF and both of them should be covered in the group of noncompetitive inhibitors.

  12. Time-oriented experimental design method to optimize hydrophilic matrix formulations with gelation kinetics and drug release profiles.

    Science.gov (United States)

    Shin, Sangmun; Choi, Du Hyung; Truong, Nguyen Khoa Viet; Kim, Nam Ah; Chu, Kyung Rok; Jeong, Seong Hoon

    2011-04-04

    A new experimental design methodology was developed by integrating the response surface methodology and the time series modeling. The major purposes were to identify significant factors in determining swelling and release rate from matrix tablets and their relative factor levels for optimizing the experimental responses. Properties of tablet swelling and drug release were assessed with ten factors and two default factors, a hydrophilic model drug (terazosin) and magnesium stearate, and compared with target values. The selected input control factors were arranged in a mixture simplex lattice design with 21 experimental runs. The obtained optimal settings for gelation were PEO, LH-11, Syloid, and Pharmacoat with weight ratios of 215.33 (88.50%), 5.68 (2.33%), 19.27 (7.92%), and 3.04 (1.25%), respectively. The optimal settings for drug release were PEO and citric acid with weight ratios of 191.99 (78.91%) and 51.32 (21.09%), respectively. Based on the results of matrix swelling and drug release, the optimal solutions, target values, and validation experiment results over time were similar and showed consistent patterns with very small biases. The experimental design methodology could be a very promising experimental design method to obtain maximum information with limited time and resources. It could also be very useful in formulation studies by providing a systematic and reliable screening method to characterize significant factors in the sustained release matrix tablet. Copyright © 2011 Elsevier B.V. All rights reserved.

  13. Furfural production from biomass pretreatment hydrolysate using vapor-releasing reactor system.

    Science.gov (United States)

    Liu, Lu; Chang, Hou-Min; Jameel, Hasan; Park, Sunkyu

    2018-03-01

    Biomass hydrolysate from autohydrolysis pretreatment was used for furfural production considering it is in rich of xylose, xylo-oligomers, and other decomposition products from hemicellulose structure. By using the vapor-releasing reactor system, furfural was protected from degradation by separating it from the reaction media. The maximum furfural yield of 73% was achieved at 200 °C for biomass hydrolysate without the use of the catalyst. This is because the presence of organic acids such as acetic acid in hydrolysate functioned as a catalyst. According to the results in this study, biomass hydrolysate with a vapor-releasing system proves to be efficient for furfural production. The biorefinery process which allows the separation of xylose-rich autohydrolysate from other parts from biomass feedstock also improves the overall application of the biomass. Copyright © 2018 Elsevier Ltd. All rights reserved.

  14. Real-time observation of DNA target interrogation and product release by the RNA-guided endonuclease CRISPR Cpf1 (Cas12a).

    Science.gov (United States)

    Singh, Digvijay; Mallon, John; Poddar, Anustup; Wang, Yanbo; Tippana, Ramreddy; Yang, Olivia; Bailey, Scott; Ha, Taekjip

    2018-05-22

    CRISPR-Cas9, which imparts adaptive immunity against foreign genomic invaders in certain prokaryotes, has been repurposed for genome-engineering applications. More recently, another RNA-guided CRISPR endonuclease called Cpf1 (also known as Cas12a) was identified and is also being repurposed. Little is known about the kinetics and mechanism of Cpf1 DNA interaction and how sequence mismatches between the DNA target and guide-RNA influence this interaction. We used single-molecule fluorescence analysis and biochemical assays to characterize DNA interrogation, cleavage, and product release by three Cpf1 orthologs. Our Cpf1 data are consistent with the DNA interrogation mechanism proposed for Cas9. They both bind any DNA in search of protospacer-adjacent motif (PAM) sequences, verify the target sequence directionally from the PAM-proximal end, and rapidly reject any targets that lack a PAM or that are poorly matched with the guide-RNA. Unlike Cas9, which requires 9 bp for stable binding and ∼16 bp for cleavage, Cpf1 requires an ∼17-bp sequence match for both stable binding and cleavage. Unlike Cas9, which does not release the DNA cleavage products, Cpf1 rapidly releases the PAM-distal cleavage product, but not the PAM-proximal product. Solution pH, reducing conditions, and 5' guanine in guide-RNA differentially affected different Cpf1 orthologs. Our findings have important implications on Cpf1-based genome engineering and manipulation applications.

  15. Reductive Alkaline Release of N-Glycans Generates a Variety of Unexpected, Useful Products.

    Science.gov (United States)

    Figl, Rudolf; Altmann, Friedrich

    2018-02-01

    Release of O-glycans by reductive β-elimination has become routine in many glyco-analytical laboratories and concomitant release of N-glycans has repeatedly been observed. Revisiting this somewhat forgotten mode of N-glycan release revealed that all kinds of N-glycans including oligomannosidic and complex-type N-glycans from plants with 3-linked fucose and from mammals with or without 6-linked fucose and with sialic acid could be recovered. However, the mass spectra of the obtained products revealed very surprising facts. Even after 16 h incubation in 1 M sodium borohydride, a large part of the glycans occurred in reducing form. Moreover, about one third emerged in the form of the stable amino-functionalized 1-amino-1-deoxy-glycitol. When avoiding acidic conditions, considerable amounts of glycosylamine were observed. In addition, a compound with a reduced asparagine and de-N-acetylation products, in particular of sialylated glycans, was seen. The relative yields of the products reducing glycosylamine, reducing N-glycan, 1-amino-1-deoxy-glycitol or glycitol could be controlled by the release conditions, foremost by temperature and borohydride concentration. Thus, chemical release of N-glycans constitutes a cost-saving alternative to enzymatic hydrolysis for the preparation of precursors for the production of reference compounds for various formats of N-glycan analysis. Moreover, it allows to obtain a stable amino-functionalized glycan derivative, which can be employed to construct glycan arrays or affinity matrices. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Intrinsic gas production kinetics of selected intermediates in anaerobic filters for demand-orientated energy supply.

    Science.gov (United States)

    Krümpel, Johannes Hagen; Illi, Lukas; Lemmer, Andreas

    2018-03-01

    As a consequence of a growing share of solar and wind power, recent research on biogas production highlighted a need for demand-orientated, flexible gas production to provide grid services and enable a decentralized stabilization of the electricity infrastructure. Two-staged anaerobic digestion is particularly suitable for shifting the methane production into times of higher demand due to the spatio-temporal separation of hydrolysis and methanogenesis. To provide a basis for predicting gas production in an anaerobic filter, kinetic parameters of gas production have been determined experimentally in this study. A new methodology is used, enabling their determination during continuous operation. An order in methane production rate could be established by comparing the half lives of methane production. The order was beginning with the fastest: acetic acid>ethanol>butyric acid>iso-butyric acid>valeric acid>propionic acid>1,2propanediol>lactic acid. However, the mixture of a natural hydrolysate from the acidification tank appeared to produce methane faster than all single components tested.

  17. Saccharification of ozonated sugarcane bagasse using enzymes from Myceliophthora thermophila JCP 1-4 for sugars release and ethanol production.

    Science.gov (United States)

    de Cassia Pereira, Josiani; Travaini, Rodolfo; Paganini Marques, Natalia; Bolado-Rodríguez, Silvia; Bocchini Martins, Daniela Alonso

    2016-03-01

    The saccharification of ozonated sugarcane bagasse (SCB) by enzymes from Myceliophthora thermophila JCP 1-4 was studied. Fungal enzymes provided slightly higher sugar release than commercial enzymes, working at 50°C. Sugar release increased with temperature increase. Kinetic studies showed remarkable glucose release (4.99 g/L, 3%w/w dry matter) at 60°C, 8 h of hydrolysis, using an enzyme load of 10 FPU (filter paper unit). FPase and β-glucosidase activities increased during saccharification (284% and 270%, respectively). No further significant improvement on glucose release was observed increasing the enzyme load above 7.5 FPU per g of cellulose. Higher dry matter contents increased sugars release, but not yields. The fermentation of hydrolysates by Saccharomyces cerevisiae provided glucose-to-ethanol conversions around to 63%. Copyright © 2015 Elsevier Ltd. All rights reserved.

  18. Single Layer Extended Release Two-in-One Guaifenesin Matrix Tablet: Formulation Method, Optimization, Release Kinetics Evaluation and Its Comparison with Mucinex® Using Box-Behnken Design.

    Science.gov (United States)

    Morovati, Amirhosein; Ghaffari, Alireza; Erfani Jabarian, Lale; Mehramizi, Ali

    2017-01-01

    Guaifenesin, a highly water-soluble active (50 mg/mL), classified as a BCS class I drug. Owing to its poor flowability and compressibility, formulating tablets especially high-dose one, may be a challenge. Direct compression may not be feasible. Bilayer tablet technology applied to Mucinex®, endures challenges to deliver a robust formulation. To overcome challenges involved in bilayer-tablet manufacturing and powder compressibility, an optimized single layer tablet prepared by a binary mixture (Two-in-one), mimicking the dual drug release character of Mucinex ® was purposed. A 3-factor, 3-level Box-Behnken design was applied to optimize seven considered dependent variables (Release "%" in 1, 2, 4, 6, 8, 10 and 12 h) regarding different levels of independent one (X 1 : Cetyl alcohol, X 2 : Starch 1500 ® , X 3 : HPMC K100M amounts). Two granule portions were prepared using melt and wet granulations, blended together prior to compression. An optimum formulation was obtained (X 1 : 37.10, X 2 : 2, X 3 : 42.49 mg). Desirability function was 0.616. F2 and f1 between release profiles of Mucinex® and the optimum formulation were 74 and 3, respectively. An n-value of about 0.5 for both optimum and Mucinex® formulations showed diffusion (Fickian) control mechanism. However, HPMC K100M rise in 70 mg accompanied cetyl alcohol rise in 60 mg led to first order kinetic (n = 0.6962). The K values of 1.56 represented an identical burst drug releases. Cetyl alcohol and starch 1500 ® modulated guaifenesin release from HPMC K100M matrices, while due to their binding properties, improved its poor flowability and compressibility, too.

  19. Monitoring and diagnostic system of fission product transport and release in nuclear power plants

    International Nuclear Information System (INIS)

    Kodaira, H.; Kondo, S.; Togo, Y.

    1983-01-01

    A monitoring and diagnostic system (MADS) of fission product (FP) transport and release in nuclear power plants (NPPs) is proposed and the conceptual design for MADS is studied. A MADS can be described in the most general way as a computer-based information processing system which takes in plant data, processes it and displays the results to the NPP's operating crew. A major concern for MADS is, however, not to evaluate general plant dynamics, but to monitor the distribution of whole radioactive materials such as FP, and to diagnose the plant state in the view of FP transport during the NPP's lifetime. Several functions demanded of MADS are: (a) during normal operation, to certify the fuel integrity and the effectiveness of the purification systems, (b) in an unusual event, to identify the event and to monitor the amount of FP release with accuracy, and (c) in case of a rare occurrence, to estimate the maximum potential release

  20. Controlled release of volatiles under mild reaction conditions: from nature to everyday products.

    Science.gov (United States)

    Herrmann, Andreas

    2007-01-01

    Volatile organic compounds serve in nature as semiochemicals for communication between species, and are often used as flavors and fragrances in our everyday life. The quite limited longevity of olfactive perception has led to the development of pro-perfumes or pro-fragrances--ideally nonvolatile and odorless fragrance precursors which release the active volatiles by bond cleavage. Only a limited amount of reaction conditions, such as hydrolysis, temperature changes, as well as the action of light, oxygen, enzymes, or microorganisms, can be used to liberate the many different chemical functionalities. This Review describes the controlled chemical release of fragrances and discusses additional challenges such as precursor stability during product storage as well as some aspects concerning toxicity and biodegradability. As the same systems can be applied in different areas of research, the scope of this Review covers fragrance delivery as well as the controlled release of volatiles in general.

  1. Accident management to prevent containment failure and reduce fission product release

    International Nuclear Information System (INIS)

    Lehner, J.R.; Lin, C.C.; Luckas, W.J.; Pratt, W.T.

    1991-01-01

    Brookhaven National Laboratory, under the auspices of the US Nuclear Regulatory Commission, is investigating accident management strategies which could help preserve containment integrity or minimize releases during a severe accident. The strategies considered make use of existing plant systems and equipment in innovative ways to reduce the likelihood of containment failure or to mitigate the release of fission products to the environment if failure cannot be prevented. Many of these strategies would be implemented during the later stages of a severe accident, i.e. after vessel breach, and sizable uncertainties exist regarding some of the phenomena involved. The identification and assessment process for containment and release strategies is described, and some insights derived from its application to specific containment types are presented. 2 refs., 5 figs., 2 tabs

  2. Production and release of the fission gas in (Th U)O2 fuel rods

    International Nuclear Information System (INIS)

    Dias, Marcio S.

    1982-06-01

    The volume, composition and release of the fission gas products were caculated for (Th, U)O 2 fuel rods. The theorectical calculations were compared with experimental results available on the literature. In ThO 2 + 5% UO 2 fuel rods it will be produced approximated 5% more fission gas as compared to UO 2 fuel rods. The fission gas composition or Xe to Kr ratio has showed a decreasing fuel brunup dependence, in opposition to that of UO 2 . Under the same fuel rod operational conditions, the (Th, U)O 2 fission gas release will be smaller as compared to UO 2 . This behaviour of (Th, U)O 2 fuel comes from smallest gas atom difusivity and higher activation energies of the processes that increase the fission gas release. (Author) [pt

  3. Transformation of benzophenone-type UV filters by chlorine: Kinetics, products identification and toxicity assessments

    International Nuclear Information System (INIS)

    Li, Jian; Ma, Li-yun; Xu, Li

    2016-01-01

    Highlights: • Chlorination kinetics of three benzophenone-type UV filters (BPs) was studied. • Chlorination of BPs followed second-order reaction. • The transformation products (TPs) of six BPs were identified. • Several transformation pathways were proposed. • Mostly enhanced toxicity of TPs after chlorination was observed. - Abstract: The present study focused on the kinetics, transformation pathways and toxicity of several benzophenone-type ultraviolet filters (BPs) during the water chlorination disinfection process. The transformation kinetics of the studied three BPs was found to be second-order reaction, which was dependent on the concentration of BPs and chlorine. The second-order rate constants increased from 86.7 to 975 M"−"1 s"−"1 for oxybenzone, 49.6–261.7 M"−"1 s"−"1 for 4-hydroxybenzophenone and 51.7–540 M"−"1 s"−"1 for 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid with the increasing pH value from 6 to 8 of the chlorination disinfection condition. Then the transformation products (TPs) of these BPs were identified by HPLC-QTof analysis. Several transformation pathways, including electrophilic substitution, methoxyl substitution, ketone groups oxidation, hydrolysis, decarboxylation and ring cleavage reaction, were speculated to participate in the chlorination transformation process. Finally, according to the toxicity experiment on luminescent bacteria, Photobacterium phosphoreum, enhanced toxicity was observed for almost all the TPs of the studied BPs except for 2,2′-dihydroxy-4,4′-dimethoxybenzophenone; it suggested the formation of TPs with more toxic than the parent compounds during the chlorination process. The present study provided a foundation to understand the transformation of BPs during chlorination disinfection process, and was of great significance to the drinking water safety.

  4. Transformation of benzophenone-type UV filters by chlorine: Kinetics, products identification and toxicity assessments

    Energy Technology Data Exchange (ETDEWEB)

    Li, Jian; Ma, Li-yun; Xu, Li, E-mail: xulpharm@mails.tjmu.edu.cn

    2016-07-05

    Highlights: • Chlorination kinetics of three benzophenone-type UV filters (BPs) was studied. • Chlorination of BPs followed second-order reaction. • The transformation products (TPs) of six BPs were identified. • Several transformation pathways were proposed. • Mostly enhanced toxicity of TPs after chlorination was observed. - Abstract: The present study focused on the kinetics, transformation pathways and toxicity of several benzophenone-type ultraviolet filters (BPs) during the water chlorination disinfection process. The transformation kinetics of the studied three BPs was found to be second-order reaction, which was dependent on the concentration of BPs and chlorine. The second-order rate constants increased from 86.7 to 975 M{sup −1} s{sup −1} for oxybenzone, 49.6–261.7 M{sup −1} s{sup −1} for 4-hydroxybenzophenone and 51.7–540 M{sup −1} s{sup −1} for 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid with the increasing pH value from 6 to 8 of the chlorination disinfection condition. Then the transformation products (TPs) of these BPs were identified by HPLC-QTof analysis. Several transformation pathways, including electrophilic substitution, methoxyl substitution, ketone groups oxidation, hydrolysis, decarboxylation and ring cleavage reaction, were speculated to participate in the chlorination transformation process. Finally, according to the toxicity experiment on luminescent bacteria, Photobacterium phosphoreum, enhanced toxicity was observed for almost all the TPs of the studied BPs except for 2,2′-dihydroxy-4,4′-dimethoxybenzophenone; it suggested the formation of TPs with more toxic than the parent compounds during the chlorination process. The present study provided a foundation to understand the transformation of BPs during chlorination disinfection process, and was of great significance to the drinking water safety.

  5. Release behavior of fission products from irradiated dispersion fuels at high temperatures

    International Nuclear Information System (INIS)

    Iwai, Takashi; Shimizu, Michio; Nakagawa, Tetsuya

    1990-02-01

    As a framework of reduced enrichment fuel program of JMTR Project, the measurements of fission products release rates at high temperatures (600degC - 1100degC) were performed in order to take the data to use for safety evaluation of LEU fuel. Three type miniplates of dispersion silicide and aluminide fuel, 20% enrichment LEU fuel with 4.8 gU/cc (U 3 Si 2 90 %, USi 10 % and U 3 Si 2 50 %, U 3 Si 50 % dispersed in aluminium) and 45 % enrichment MEU fuel with 1.6 gU/cc, were irradiated in JMTR. The burnups attained by one cycle (22 days) irradiation were within 21.6 % - 22.5 % of initial 235 U. The specimens cut down from miniplates were measured on fission products release rates by means of new apparatus specially designed for this experiment. The specimens were heated up within 600degC - 1100degC in dry air. Then fission products such as 85 Kr, 133 Xe, 131 I, 137 Cs, 103 Ru, 129m Te were collected at each temperature and measured on release rates. In the results of measurement, the release rates of 85 Kr, 133 Xe, 131 I, 129m Te from all specimens were slightly less than that of G.W. Parker's data on U-Al alloy fuel. For 137 Cs and 103 Ru from a silicide specimen (U 3 Si 2 90 %, USi 10 % dispersed in aluminium) and 137 Cs from an aluminide specimen, the release rates were slightly higher than that of G.W. Parker's. (author)

  6. Kinetic modeling of light limitation and sulfur deprivation effects in the induction of hydrogen production with Chlamydomonas reinhardtii: Part I. Model development and parameter identification.

    Science.gov (United States)

    Fouchard, Swanny; Pruvost, Jérémy; Degrenne, Benoit; Titica, Mariana; Legrand, Jack

    2009-01-01

    Chlamydomonas reinhardtii is a green microalga capable of turning its metabolism towards H2 production under specific conditions. However this H2 production, narrowly linked to the photosynthetic process, results from complex metabolic reactions highly dependent on the environmental conditions of the cells. A kinetic model has been developed to relate culture evolution from standard photosynthetic growth to H2 producing cells. It represents transition in sulfur-deprived conditions, known to lead to H2 production in Chlamydomonas reinhardtii, and the two main processes then induced which are an over-accumulation of intracellular starch and a progressive reduction of PSII activity for anoxia achievement. Because these phenomena are directly linked to the photosynthetic growth, two kinetic models were associated, the first (one) introducing light dependency (Haldane type model associated to a radiative light transfer model), the second (one) making growth a function of available sulfur amount under extracellular and intracellular forms (Droop formulation). The model parameters identification was realized from experimental data obtained with especially designed experiments and a sensitivity analysis of the model to its parameters was also conducted. Model behavior was finally studied showing interdependency between light transfer conditions, photosynthetic growth, sulfate uptake, photosynthetic activity and O2 release, during transition from oxygenic growth to anoxic H2 production conditions.

  7. Kinetics of ethanol production from Jerusalem artichoke juice with some Klugveromyces species

    Energy Technology Data Exchange (ETDEWEB)

    Duvnjak, Z.; Kosaric, N.; Hayes, R.D.

    1981-01-01

    The kinetics of ethanol produce by Kluyveromyces marxianus ATCC 12708 and ATCC 10606, K. cicerisporus ATCC 22295, and K. fragilis 105 have been studied using raw juice of the Jerusalem artichoke in which the carbohydrates were not hydrolyzed prior to fermentation. The experiments revealed that this juice contains enough nutrients and can serve as a complete medium without additional nutrients both for growth of the yeasts and for ethanol production. It was found that both specific ethanol productivity and specific uptake rates were the highest with K. marxianus ATCC 12708 (1.68 g/g/hour and 3.78 g/g/hour respectively). This microorganism produced an ethanol yield of 87.5% of the theoretical value in 25 hours. (Refs. 15).

  8. Inhibition of clone formation as an assay for T cell-mediated cytotoxicity: short-term kinetics and comparison with 51Cr release

    International Nuclear Information System (INIS)

    Lees, R.K.; MacDonald, H.R.; Sinclair, N.R.; University of Western Ontario London

    1977-01-01

    The short-term kinetics of T cell-mediated cytotoxicity was investigated using a cloning inhibition assay. Murine cytotoxic thymus-derived lymphocytes generated in vitro in mixed leukocyte cultures were incubated for various periods of time at 37degC with allogeneic mastocytoma target cells. The mixtures were then plated in soft agar, and mastocytoma clone formation was assessed after 5-7 days incubation. Using this technique, it was demonstrated that events leading to the loss of cloning ability could be detected after 1-3 min incubation at 37degC, and after 20-30 min, 95% of the clone forming cells had been inactivated. When these results were compared directly with those obtained using the conventional 51 Cr-release assay, it was found that the events leading to loss of cloning ability occurred more rapidly than indicated by the isotope assay. However, a modification of the 51 Cr-release assay involving EDTA addition gave comparable result to the cloning inhibition assay. These results raise the possibility that the events leading to 51 Cr-release of tumor target cells may be related in time to those leading to the loss of cloning ability

  9. Kinetic analysis of in vitro production of wild-type Spodoptera frugiperda nucleopolyhedrovirus

    Directory of Open Access Journals (Sweden)

    Andréa Farias de Almeida

    2010-04-01

    Full Text Available In this study, the kinetic behavior of Sf9 and Sf21 cells used in the production of a baculovirus biopesticide to control the pest of corn Spodoptera frugiperda was analyzed. Kinetic variables such as maximum specific growth rate, cell productivity, mean rate of infection, as well as the mean rate of occlusion body production were determined during the infection of these cell-lines with the extracellular virus of the S. frugiperda nucleopolyhedrovirus (SfMNPV. The Sf9 cell-line resulted in better viral production results (5.0 x 10(8 OB/mL than the Sf21 cell-line (2.5 x 10(8 OB/mL.Neste trabalho, analisou-se o comportamento cinético das células Sf9 e Sf21 utilizadas na produção de biopesticida para o controle de Spodoptera frugiperda. Variáveis cinéticas, como velocidade específica máxima de crescimento, produtividade em células, velocidade média de infecção e a velocidade média de produção de OB foram determinadas durante a infecção destas linhagens com o vírus extracelular do nucleopoliedrovirus de S. frugiperda. A linhagem Sf9 resultou em melhores resultados de produção do baculovírus (5 x 10(8 OB/mL, quando comparada à linhagem Sf21 (2,5 x 10(8 OB/mL e outras linhagens da literatura.

  10. Fission Product Releases from a Core into a Coolant of a Prismatic 350-MWth HTR

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Young Min; Jo, C. K. [KAERI, Daejeon (Korea, Republic of)

    2016-05-15

    A prismatic 350-MW{sub th} high temperature reactor (HTR) is a means to generate electricity and process heat for hydrogen production. The HTR will be operated for an extended fuel burnup of more than 150 GWd/MTU. Korea Atomic Energy Research Institute (KAERI) is performing a point design for the HTR which is a pre-conceptual design for the analysis and assessment of engineering feasibility of the reactor. In a prismatic HTR, metallic and gaseous fission products (FPs) are produced in the fuel, moved through fuel materials, and released into a primary coolant. The FPs released into the coolant are deposited on the various helium-wetted surfaces in the primary circuit, or they are sorbed on particulate matters in the primary coolant. The deposited or sorbed FPs are released into the environment through the leakage or venting of the primary coolant. It is necessary to rigorously estimate such radioactivity releases into the environment for securing the health and safety of the occupational personnel and the public. This study treats the FP releases from a core into a coolant of a prismatic 350-MW{sub th} HTR. These results can be utilized as input data for the estimation of FP migration from a coolant into the environment. The analysis of fission product release within a prismatic 350-MW{sub th} HTR has been done. It was assumed that the HTR was operated at constant temperature and power for 1500 EFPDs. - The final burnup is 152 GWd/tHM at packing fraction of 25 %, and the final fast fluence is about 8 X 10{sup 21} n/cm{sup 2}, E{sub n} > 0.1 MeV. - The temperatures at the compact center and at the center of a kernel located at the compact center are 884 and 893 .deg. C, respectively, when the packing fraction is 25 % and the coolant temperature is 850 .deg. C. - Xenon is the most radioactive fission product in a coolant of a prismatic HTR when there are broken TRISOs and fuel component contaminated with heavy metals. For metallic fission products, the radioactivity

  11. Kinetic studies on batch cultivation of Trichoderma reesei and application to enhance cellulase production by fed-batch fermentation.

    Science.gov (United States)

    Ma, Lijuan; Li, Chen; Yang, Zhenhua; Jia, Wendi; Zhang, Dongyuan; Chen, Shulin

    2013-07-20

    Reducing the production cost of cellulase as the key enzyme for cellulose hydrolysis to fermentable sugars remains a major challenge for biofuel production. Because of the complexity of cellulase production, kinetic modeling and mass balance calculation can be used as effective tools for process design and optimization. In this study, kinetic models for cell growth, substrate consumption and cellulase production in batch fermentation were developed, and then applied in fed-batch fermentation to enhance cellulase production. Inhibition effect of substrate was considered and a modified Luedeking-Piret model was developed for cellulase production and substrate consumption according to the growth characteristics of Trichoderma reesei. The model predictions fit well with the experimental data. Simulation results showed that higher initial substrate concentration led to decrease of cellulase production rate. Mass balance and kinetic simulation results were applied to determine the feeding strategy. Cellulase production and its corresponding productivity increased by 82.13% after employing the proper feeding strategy in fed-batch fermentation. This method combining mathematics and chemometrics by kinetic modeling and mass balance can not only improve cellulase fermentation process, but also help to better understand the cellulase fermentation process. The model development can also provide insight to other similar fermentation processes. Copyright © 2013 Elsevier B.V. All rights reserved.

  12. The Effect of Ethanol Addition to Gasoline on Low- and Intermediate-Temperature Heat Release under Boosted Conditions in Kinetically Controlled Engines

    Science.gov (United States)

    Vuilleumier, David Malcolm

    The detailed study of chemical kinetics in engines has become required to further advance engine efficiency while simultaneously lowering engine emissions. This push for higher efficiency engines is not caused by a lack of oil, but by efforts to reduce anthropogenic carbon dioxide emissions, that cause global warming. To operate in more efficient manners while reducing traditional pollutant emissions, modern internal combustion piston engines are forced to operate in regimes in which combustion is no longer fully transport limited, and instead is at least partially governed by chemical kinetics of combusting mixtures. Kinetically-controlled combustion allows the operation of piston engines at high compression ratios, with partially-premixed dilute charges; these operating conditions simultaneously provide high thermodynamic efficiency and low pollutant formation. The investigations presented in this dissertation study the effect of ethanol addition on the low-temperature chemistry of gasoline type fuels in engines. These investigations are carried out both in a simplified, fundamental engine experiment, named Homogeneous Charge Compression Ignition, as well as in more applied engine systems, named Gasoline Compression Ignition engines and Partial Fuel Stratification engines. These experimental investigations, and the accompanying modeling work, show that ethanol is an effective scavenger of radicals at low temperatures, and this inhibits the low temperature pathways of gasoline oxidation. Further, the investigations measure the sensitivity of gasoline auto-ignition to system pressure at conditions that are relevant to modern engines. It is shown that at pressures above 40 bar and temperatures below 850 Kelvin, gasoline begins to exhibit Low-Temperature Heat Release. However, the addition of 20% ethanol raises the pressure requirement to 60 bar, while the temperature requirement remains unchanged. These findings have major implications for a range of modern engines

  13. Fission product release from high gap-inventory LWR fuel under LOCA conditions

    International Nuclear Information System (INIS)

    Lorenz, R.A.; Collins, J.L.; Osborne, M.F.; Malinauskas, A.P.

    1980-01-01

    Fission product release tests were performed with light water reactor (LWR) fuel rod segments containing large amounts of cesium and iodine in the pellet-to-cladding gap space in order to check the validity of the previously published Source Term Model for this type of fuel. The model describes the release of fission product cesium and iodine from LWR fuel rods for controlled loss-of-coolant accident (LOCA) transients in the temperature range 500 to 1200 0 C. The basis for the model was test data obtained with simulated fuel rods and commercial fuel irradiated to high burnup but containing relatively small amounts of cesium and iodine in the pellet-to-cladding gap space

  14. Use of slow-release fertilizer on the production of sweet potatoes plantlets in tray

    Directory of Open Access Journals (Sweden)

    Amarílis Beraldo Rós

    2013-12-01

    Full Text Available The production of plantlets in containers generally requires the use of fertilizers. The aim of this study was to evaluate the production of sweet potato in styrofoam trays using slow-release fertilizer. The experiment was carried out, under a screen-protected nursery, in a factorial scheme 5x5, with five doses of slow-release fertilizer NPK 19-06-10 (0, 50, 100, 150 e 200 g per 25 kg de substrate and five times of plantlets permanence in tray (14, 28, 42, 56 and 70 days after planting the cuttings. The number and dry matter of roots and leaves were evaluated. The number of roots was not influenced by fertilizer addition. In general, there is not damage to plantlets growth until the highest dose used. Therefore, the fertilizer addition increases the sweet potato plants growth and the dose of 200 g per 25 kg of substrate is responsible for the best results.

  15. End product inhibition of hepatic 25-hydroxyvitamin D production in the rat: specificity and kinetics

    International Nuclear Information System (INIS)

    Milne, M.L.; Baran, D.T.

    1985-01-01

    The role of vitamin D metabolites in the regulation of hepatic 25-hydroxyvitamin D production was investigated by examining the effects of 25-hydroxyvitamin D, 1,25-dihydroxyvitamin D, and 24,25-dihydroxyvitamin D on the synthesis of [25- 3 H]hydroxyvitamin D by rachitic rat liver homogenates. Production of [25- 3 H]hydroxyvitamin D was inhibited by 25-hydroxyvitamin D and 1,25-dihydroxyvitamin D, but not by 24,25-dihydroxyvitamin D. 25-Hydroxyvitamin D increased the Km of the vitamin D-25-hydroxylase enzyme(s), while 1,25-dihydroxyvitamin D decreased the Vmax with a Ki of 88.7 ng/ml. Inhibition of hepatic 25-hydroxyvitamin D production by 25-hydroxyvitamin D and 1,25-dihydroxyvitamin D may be another control mechanism to regulate circulating vitamin D levels

  16. French practice for assessing the fission product releases from the containment during a PWR severe accident

    International Nuclear Information System (INIS)

    Duco, J.; Dufresne, J.; L'homme, A.

    1988-10-01

    French safety philosophy as concerns severe PWR accidents has already been outlined by the Director of CEA/IPSN in an article published in ''Nuclear Safety''. Therefore the present paper will focus on: a) the French reference source terms, as used for elaborating ultimate emergency procedures on PWRs and for emergency planning; b) the methods currently developed for more realistic assessments of the release of fission products during a severe accident

  17. Release of radioactive fission products from BN-600 reactor untight fuel elements

    International Nuclear Information System (INIS)

    Osipov, S.L.; Tsikunov, A.G.; Lisitsin, E.C.

    1996-01-01

    The experimental data on the release of radioactive fission products from BN-600 reactor untight fuel elements are given in the report. Various groups of radionuclides: inert gases Xe, Kr, volatile Cs, J, non-volatile Nb, and La are considered. The results of calculation-experimental study of transfer and distribution of radionuclides in the reactor primary circuit, gas system and sodium coolant are considered. It is shown that some complex radioactivity transfer processes can be described by simple mathematical models. (author)

  18. Kinetic of orange pigment production from Monascus ruber on submerged fermentation.

    Science.gov (United States)

    Vendruscolo, Francielo; Schmidell, Willibaldo; de Oliveira, Débora; Ninow, Jorge Luiz

    2017-01-01

    Pigments produced by species of Monascus have been used to coloring rice, meat, sauces, wines and beers in East Asian countries. Monascus can produce orange (precursor), yellow and red pigments. Orange pigments have low solubility in culture media and when react with amino groups they become red and largely soluble. The orange pigments are an alternative to industrial pigment production because the low solubility facilitates the downstream operations. The aim of this work was to study the kinetic on the production of orange pigments by Monascus ruber CCT 3802. The shaking frequency of 300 rpm was favorable to production, whereas higher shaking frequencies showed negative effect. Pigment production was partially associated with cell growth, the critical dissolved oxygen concentration was between 0.894 and 1.388 mgO 2  L -1 at 30 °C, and limiting conditions of dissolved oxygen decreased the production of orange pigments. The maintenance coefficient (mo) and the conversion factor of oxygen in biomass (Yo) were 18.603 mgO 2  g x -1  h -1 and 3.133 g x  gO 2 -1 and the consideration of these parameters in the oxygen balance to estimate the biomass concentration provided good fits to the experimental data.

  19. Biogas Production from Sugarcane Waste: Assessment on Kinetic Challenges for Process Designing

    Science.gov (United States)

    Janke, Leandro; Leite, Athaydes; Nikolausz, Marcell; Schmidt, Thomas; Liebetrau, Jan; Nelles, Michael; Stinner, Walter

    2015-01-01

    Biogas production from sugarcane waste has large potential for energy generation, however, to enable the optimization of the anaerobic digestion (AD) process each substrate characteristic should be carefully evaluated. In this study, the kinetic challenges for biogas production from different types of sugarcane waste were assessed. Samples of vinasse, filter cake, bagasse, and straw were analyzed in terms of total and volatile solids, chemical oxygen demand, macronutrients, trace elements, and nutritional value. Biochemical methane potential assays were performed to evaluate the energy potential of the substrates according to different types of sugarcane plants. Methane yields varied considerably (5–181 Nm3·tonFM−1), mainly due to the different substrate characteristics and sugar and/or ethanol production processes. Therefore, for the optimization of AD on a large-scale, continuous stirred-tank reactor with long hydraulic retention times (>35 days) should be used for biogas production from bagasse and straw, coupled with pre-treatment process to enhance the degradation of the fibrous carbohydrates. Biomass immobilization systems are recommended in case vinasse is used as substrate, due to its low solid content, while filter cake could complement the biogas production from vinasse during the sugarcane offseason, providing a higher utilization of the biogas system during the entire year. PMID:26404248

  20. The release kinetics, antimicrobial activity and cytocompatibility of differently prepared collagen/hydroxyapatite/vancomycin layers: Microstructure vs. nanostructure

    Czech Academy of Sciences Publication Activity Database

    Suchý, Tomáš; Šupová, Monika; Klapková, E.; Adámková, V.; Závora, J.; Žaloudková, Margit; Rýglová, Šárka; Ballay, R.; Denk, František; Pokorný, M.; Sauerová, P.; Hubálek Kalbáčová, M.; Horný, L.; Veselý, J.; Voňavková, T.; Průša, R.

    2017-01-01

    Roč. 100, MAR 30 (2017), s. 219-229 ISSN 0928-0987 R&D Projects: GA TA ČR(CZ) TA04010330 Institutional support: RVO:67985891 Keywords : coating * controlled release * drug delivery system * nanoparticle * pharmacokinetics * polymeric drug delivery system Subject RIV: FS - Medical Facilities ; Equipment OBOR OECD: Biomaterials (as related to medical implants, devices, sensors) Impact factor: 3.756, year: 2016

  1. Linear free energy correlations for fission product release from the Fukushima-Daiichi nuclear accident.

    Science.gov (United States)

    Abrecht, David G; Schwantes, Jon M

    2015-03-03

    This paper extends the preliminary linear free energy correlations for radionuclide release performed by Schwantes et al., following the Fukushima-Daiichi Nuclear Power Plant accident. Through evaluations of the molar fractionations of radionuclides deposited in the soil relative to modeled radionuclide inventories, we confirm the initial source of the radionuclides to the environment to be from active reactors rather than the spent fuel pool. Linear correlations of the form In χ = −α ((ΔGrxn°(TC))/(RTC)) + β were obtained between the deposited concentrations, and the reduction potentials of the fission product oxide species using multiple reduction schemes to calculate ΔG°rxn (TC). These models allowed an estimate of the upper bound for the reactor temperatures of TC between 2015 and 2060 K, providing insight into the limiting factors to vaporization and release of fission products during the reactor accident. Estimates of the release of medium-lived fission products 90Sr, 121mSn, 147Pm, 144Ce, 152Eu, 154Eu, 155Eu, and 151Sm through atmospheric venting during the first month following the accident were obtained, indicating that large quantities of 90Sr and radioactive lanthanides were likely to remain in the damaged reactor cores.

  2. Shape-Controlled Synthesis of Colloidal Metal Nanocrystals: Thermodynamic versus Kinetic Products.

    Science.gov (United States)

    Xia, Younan; Xia, Xiaohu; Peng, Hsin-Chieh

    2015-07-01

    This Perspective provides a contemporary understanding of the shape evolution of colloidal metal nanocrystals under thermodynamically and kinetically controlled conditions. It has been extremely challenging to investigate this subject in the setting of one-pot synthesis because both the type and number of seeds involved would be changed whenever the experimental conditions are altered, making it essentially impossible to draw conclusions when comparing the outcomes of two syntheses conducted under different conditions. Because of the uncertainty about seeds, most of the mechanistic insights reported in literature for one-pot syntheses of metal nanocrystals with different shapes are either incomplete or ambiguous, and some of them might be misleading or even wrong. Recently, with the use of well-defined seeds for such syntheses, it became possible to separate growth from nucleation and therefore investigate the explicit role(s) played by a specific thermodynamic or kinetic parameter in directing the evolution of colloidal metal nanocrystals into a specific shape. Starting from single-crystal seeds enclosed by a mix of {100}, {111}, and {110} facets, for example, one can obtain colloidal nanocrystals with diversified shapes by adjusting various thermodynamic or kinetic parameters. The mechanistic insights learnt from these studies can also be extended to account for the products of conventional one-pot syntheses that involve self-nucleation only. The knowledge can be further applied to many other types of seeds with twin defects or stacking faults, making it an exciting time to design and synthesize colloidal metal nanocrystals with the shapes sought for a variety of fundamental studies and technologically important applications.

  3. A systematic literature review of Releasing Time to Care: The Productive Ward.

    Science.gov (United States)

    Wright, Stella; McSherry, Wilfred

    2013-05-01

    This systematic review provides an overview of the literature published on Releasing Time to Care: The Productive Ward between 2005 and June 2011. Releasing Time to Care: The Productive Ward programme was developed by the NHS Institute for Innovation and Improvement and launched in England in 2007. The programme comprises thirteen modules that aim to increase time for direct patient care, improve the patient and staff experience and make changes to the ward environment to improve efficiency. A systematic literature review. The terms 'Releasing Time to Care' and 'Productive Ward' were applied to key healthcare databases; CINAHL, Medline, Science Direct, ProQuest, Health Business Elite, British Nursing Index, Embase, Health Management Information Consortium and PsychInfo. All papers were read and subject to a quality assessment. The literature search identified 95 unique sources. A lack of research on The Productive Ward programme meant it was necessary to include non-empirical literature. In total, 18 articles met the inclusion criteria. Seven key themes were identified: the patient and staff experience, direct care time, patient safety, financial impact, embedding and sustainability, executive support and leadership, and common barriers and determinants of success. It also highlighted areas that require further exploration such as long-term sustainability of the programme and consistent data measurement between organisations. The review tentatively reports how The Productive Ward programme has been used to transform nursing practice for the benefit of patients and frontline staff, and how it resulted in cost savings. The literature review identified a potential positive results bias in the current literature whereby favourable outcomes were reported. This paper summarises the types of evidence and current literature on The Productive Ward providing a reference for frontline staff implementing the programme. © 2013 Blackwell Publishing Ltd.

  4. Modelling of fission product release behavior from HTR spherical fuel elements under accident conditions

    International Nuclear Information System (INIS)

    Verfondern, K.; Mueller, D.

    1991-01-01

    Computer codes for modelling the fission product release behavior of spherical fuel elements for High Temperature Reactors (HTR) have been developed for the purpose of being used in risk analyses for HTRs. An important part of the validation and verification procedure for these calculation models is the theoretical investigation of accident simulation experiments which have been conducted in the KueFA test facility in the Hot Cells at KFA. The paper gives a presentation of the basic modeling and the calculational results of fission product release from modern German HTR fuel elements in the temperature range 1600-1800 deg. C using the TRISO coated particle failure model PANAMA and the diffusion model FRESCO. Measurements of the transient release behavior for cesium and strontium and of their concentration profiles after heating have provided informations about diffusion data in the important retention barriers of the fuel: silicon carbide and matrix graphite. It could be shown that the diffusion coefficients of both cesium and strontium in silicon carbide can significantly be reduced using a factor in the range of 0.02 - 0.15 compared to older HTR fuel. Also in the development of fuel element graphite, a tendency towards lower diffusion coefficients for both nuclides can be derived. Special heating tests focussing on the fission gases and iodine release from the matrix contamination have been evaluated to derive corresponding effective diffusion data for iodine in fuel element graphite which are more realistic than the iodine transport data used so far. Finally, a prediction of krypton and cesium release from spherical fuel elements under heating conditions will be given for fuel elements which at present are irradiated in the FRJ2, Juelich, and which are intended to be heated at 1600/1800 deg. C in the KueFA furnace in near future. (author). 7 refs, 11 figs

  5. Kinetic Modeling of the Release of Ethylene Oxide from Sterilized Plastic Containers and its Interaction with Monoclonal Antibodies.

    Science.gov (United States)

    Yu, Bryan Lei; Han, Jun; Hammond, Matthew; Wang, Xuemei; Zhang, Qingchun; Clausen, Andrew; Forster, Ronald; Eu, Mingda

    Ethylene oxide (ETO) is commonly used to sterilize plastic containers, but the effects of residual amounts left after sterilization on protein therapeutics are still not well understood. Here we focus primarily on the factors that influence concentrations of ETO migrating from ETO-treated plastic containers into aqueous solution. A study was designed to investigate the kinetics of this process at various temperatures, and the kinetic data could be fit with a model based on a combination of Fickean diffusion and first-order chemical reaction (to account for observed hydrolysis of ETO). The diffusion and reaction rate constants thus obtained obey Arrhenius-like temperature dependence. These results indicate that for analytical methods involving extraction into water, measurements of residual ETO in a container must account for the effects of ETO hydrolysis. Further, the effects of salt concentration and pH of the fluid in the container on accumulated ETO levels were explored. Finally, interactions of ETO with anti-streptavidin (AntiSA) Immunoglobulin G1 (IgG1) and IgG2 antibodies were studied, with ETO adducts found on all methionine residues when incubated in solutions spiked with ETO at concentrations that could be reached (based on the kinetic studies) in ETO-treated plastic vials. Overall, the likelihood of observable ETO-protein modifications upon storage in ETO-sterilized containers will depend on a complex interplay of protein properties, formulation details, storage conditions, and amount of residual ETO initially in the container. Ethylene oxide (ETO) is commonly used to sterilize plastic containers, but the effects of residual amounts left after sterilization on protein therapeutics are still not well understood. Here we describe experiments exploring the factors that influence concentrations of ETO migrating from ETO-treated plastic containers into aqueous solution over time. Additionally, interactions of ETO with model antibodies were studied, with ETO

  6. Releases of selected alkylphenols and alkylphenol ethoxylates and use in consumer products

    DEFF Research Database (Denmark)

    Lassen, Carsten; Warming, Marlies; Fauser, Patrik

    /APE to the environment and the significance of the different sources, and  to establish an overview of the use of AP/APE in consumer products as background for consid-erations regarding the potential for consumer exposure. This report presents the results of the surveys undertaken from August 2013 to August 2014...... EPA has initiated a survey of emissions of alkylphenols and al-kylphenol ethoxylates from all life cycle stages of the substances and a survey of the use of the sub-stances in consumer products. The main objectives of the surveys are:  to establish an overview of the releases of the AP...

  7. Apparatus for measuring the release of fission gases and other fission products by degassing

    Energy Technology Data Exchange (ETDEWEB)

    Stradal, Karl Alfred

    1970-10-15

    In gas-cooled high-temperature reactors, the fuel is, in general, inserted in the fuel elements in the form of small particles, which are, for example, coated with pyrolytic carbon. The purpose of this coating is to keep the fission products separate from the coolant gas. The further development of these coated particles makes it necessary to check the retention capacity. One possible method of doing this is the degassing test after irradiation in the reactor. An apparatus is described below, which was developed and installed in order to measure to a higher degree of sensitivity and in serial measurements the release of fission gases and sparingly volatile fission products.

  8. Kinetics of two-stage fermentation process for the production of hydrogen

    Energy Technology Data Exchange (ETDEWEB)

    Nath, Kaushik [Department of Chemical Engineering, G.H. Patel College of Engineering and Technology, Vallabh Vidyanagar 388 120, Gujarat (India); Muthukumar, Manoj; Kumar, Anish; Das, Debabrata [Fermentation Technology Laboratory, Department of Biotechnology, Indian Institute of Technology, Kharagpur 721302 (India)

    2008-02-15

    Two-stage process described in the present work is a combination of dark and photofermentation in a sequential batch mode. In the first stage glucose is fermented to acetate, CO{sub 2} and H{sub 2} in an anaerobic dark fermentation by Enterobacter cloacae DM11. This is followed by a successive second stage where acetate is converted to H{sub 2} and CO{sub 2} in a photobioreactor by photosynthetic bacteria, Rhodobacter sphaeroides O.U. 001. The yield of hydrogen in the first stage was about 3.31molH{sub 2}(molglucose){sup -1} (approximately 82% of theoretical) and that in the second stage was about 1.5-1.72molH{sub 2}(molaceticacid){sup -1} (approximately 37-43% of theoretical). The overall yield of hydrogen in two-stage process considering glucose as preliminary substrate was found to be higher compared to a single stage process. Monod model, with incorporation of substrate inhibition term, has been used to determine the growth kinetic parameters for the first stage. The values of maximum specific growth rate ({mu} {sub max}) and K{sub s} (saturation constant) were 0.398h{sup -1} and 5.509gl{sup -1}, respectively, using glucose as substrate. The experimental substrate and biomass concentration profiles have good resemblance with those obtained by kinetic model predictions. A model based on logistic equation has been developed to describe the growth of R. sphaeroides O.U 001 in the second stage. Modified Gompertz equation was applied to estimate the hydrogen production potential, rate and lag phase time in a batch process for various initial concentration of glucose, based on the cumulative hydrogen production curves. Both the curve fitting and statistical analysis showed that the equation was suitable to describe the progress of cumulative hydrogen production. (author)

  9. Analysis of fission product release from HTGR core during transient temperature excursion

    International Nuclear Information System (INIS)

    Saito, Takao; Yamatoya, Naotoshi; Onuma, Mamoru

    1978-01-01

    The computer program ''FRANC'' was developed to calculate the release activity of fission products from a high-temperature gas cooled reactor (HTGR) core during transient temperature excursions such as a hypothetical loss of forced circulation combined with design basis depressurization. The program utilizes a segmented cylindrical core spatial model with the associated values of the prior fuel irradiation history and temperature conditions. The fission product transport and decay chain behavior is expressed by a set of differential equations. This set of equations describes the entire core inventory of fission products by means of calculated parameters based on the detailed spatial core conditions. The program determines the time-dependent amounts of fission product nuclides escaping from the core into the coolant. Coded in Continuous System Simulation Language (CSSL) with double precision, FRANC showed appropriate results for both short- and long-lived fission product nuclides. The sample calculation conducted by applying the program to a large HTGR indicated that it would take about one hour for noble gases and volatile nuclides to be released to the coolant, and several hours for metalic nuclides. (auth.)

  10. Simulation of rumen fermentation kinetics of by-products from the biodiesel industry with in vitro gas production technique

    Directory of Open Access Journals (Sweden)

    Alex Lopes da Silva

    2015-12-01

    Full Text Available The objective of this study was to investigate the rumen fermentation kinetics of 18 by-products from the biodiesel industry exhibiting potential for use in the feeding of ruminants via the in vitro gas production technique. The following feeds were investigated: cottonseed, canudo de pito, crambe, sunflower, castor seed (detoxified with lime and soybean meals and cottonseed, peanut, babassu, crambe, palm kernel, sunflower, licuri nut, macaúba, forage radish and jatropha cakes. The evaluated parameters were total gas production (VfT, gas production from fibrous carbohydrates (VfFC, gas production from non-fibrous carbohydrates (VfNFC, the degradation rate of fibrous carbohydrates (kdFC, the degradation rate of non-fibrous carbohydrates (kdNFC and lag time (lag. The feeds were grouped into six different groups according to rumen fermentation kinetic parameters and adopting an R2 of 0.8. Forage radish cake and the meals of cottonseed, soybean, crambe and sunflower composed the first group, while the cakes of babassu and sunflower formed the second group. Canudo de pito and castor seed meals and the cakes of cottonseed, licuri and jatropha I and II formed the third group. The fourth group was composed by the cakes of crambe, palm kernel and peanut I. The fifth group was formed by peanut cake II, while macauba fruit cake formed the sixth group. The VfNFC and VfFC varied from 16.72 to 200.07 mL and from 53.09 to 242.12 mL, respectively. The mean kdFC and kdNFC values varied from 0.002 to 0.039% h-1and from 0.022 to 0.430% h-1, respectively. The mean lag and VfT varied from 0.0001 to 5.2029 hours and 136.94 to 301.44 mL, respectively. A number of the products exhibited the potential to replace soybean meal, especially the forage radish cake and cottonseed, crambe and sunflower meals.

  11. Synthesis of novel ICIE16/BSG and ICIE16/BSG-NITRI bioglasses and description of ionic release kinetics upon immersion in SBF fluid: Effect of nitridation

    Directory of Open Access Journals (Sweden)

    Felipe Orgaz

    2016-03-01

    Full Text Available A novel bioactive glass scaffold ICIE16/BSG has been prepared from a mixture of two different melt-derived glasses: a silicate bioglass (ICIE16 and a borosilicate bioglass (BSG. Combined processing techniques (gel casting and foam replication were used to form three-dimensional, interconnected porous monolith scaffolds (Orgaz et al., 2016 [1]. They were then nitrided with a hot ammonia flow as described in (Aleixandre et al., 1973 [3] and (Nieto, 1984 [4] to synthesize the ICIE16/BSG-NITRI bioglass (Orgaz et al., 2016 [1]. Herein we present a flow chart summarizing the forming process, plus images of the resulting scaffold after sintering and drying. Bioactivity was characterized in vitro by immersion in simulated body fluid (SBF for up to seven days. Data of ionic release kinetics upon SBF immersion are presented. Keywords: Biomaterials, Bioglass, Simulated body fluid, Degradability, Biomaterial resorption, Bone repair

  12. Uptake and release kinetics of 134Cs by goldfish (Carassius auratus) and 137Cs by zebra fish (Brachydanio rerio) in controlled aquatic environment

    International Nuclear Information System (INIS)

    Srivastava, A.; Reddy, S.J.; Kelber, O.; Urich, K.; Denschlag, H.O.

    1994-01-01

    The uptake and release kinetics of 134 Cs by Goldfish (Carassius auratus) and 137 Cs by Zebra Fish (Brachydanio rerio) from aquatic media of different ionic compositions and temperature was studied in controlled laboratory conditions. The accumulation of radiocesium in the case of Brachydanio rerio is observed to be strongly dependent on the potassium ion concentration of the aquatic medium, but in the case of Carassius auratus this dependence is quite weak. The biological half-lives of the cesium isotopes incorporated into the fish investigated in the present work vary from 19 to 80 days and are influenced by the temperature and the ionic composition of the aquatic medium. (author) 19 refs.; 1 fig.; 3 tabs

  13. Kinetics of levulinic acid and furfural production from Miscanthus × giganteus.

    Science.gov (United States)

    Dussan, K; Girisuta, B; Haverty, D; Leahy, J J; Hayes, M H B

    2013-12-01

    This study investigated the kinetics of acid hydrolysis of the cellulose and hemicellulose in Miscanthus to produce levulinic acid and furfural under mild temperature and high acid concentration. Experiments were carried out in an 8L-batch reactor with 9%-wt. biomass loading, acid concentrations between 0.10 and 0.53 M H2SO4, and at temperatures between 150 and 200°C. The concentrations of xylose, glucose, furfural, 5-hydroxymethylfurfural and levulinic acid were used in two mechanistic kinetic models for the prediction of the performance of ideal continuous reactors for the optimisation of levulinic acid and the concurrent production of furfural. A two-stage arrangement was found to maximise furfural in the first reactor (PFR - 185°C, 0.5M H2SO4, 27.3%-mol). A second stage leads to levulinic acid yields between 58% and 72%-mol at temperatures between 160 and 200°C. Copyright © 2013 Elsevier Ltd. All rights reserved.

  14. Oxidation of β-lactam antibiotics by peracetic acid: Reaction kinetics, product and pathway evaluation.

    Science.gov (United States)

    Zhang, Kejia; Zhou, Xinyan; Du, Penghui; Zhang, Tuqiao; Cai, Meiquan; Sun, Peizhe; Huang, Ching-Hua

    2017-10-15

    Peracetic acid (PAA) is a disinfection oxidant used in many industries including wastewater treatment. β-Lactams, a group of widely prescribed antibiotics, are frequently detected in wastewater effluents and surface waters. The reaction kinetics and transformation of seven β-lactams (cefalexin (CFX), cefadroxil (CFR), cefapirin (CFP), cephalothin (CFT), ampicillin (AMP), amoxicillin (AMX) and penicillin G (PG)) toward PAA were investigated to elucidate the behavior of β-lactams during PAA oxidation processes. The reaction follows second-order kinetics and is much faster at pH 5 and 7 than at pH 9 due to speciation of PAA. Reactivity to PAA follows the order of CFR ∼ CFX > AMP ∼ AMX > CFT ∼ CFP ∼ PG and is related to β-lactam's nucleophilicity. The thioether sulfur of β-lactams is attacked by PAA to generate sulfoxide products. Presence of the phenylglycinyl amino group on β-lactams can significantly influence electron distribution and the highest occupied molecular orbital (HOMO) location and energy in ways that enhance the reactivity to PAA. Reaction rate constants obtained in clean water matrix can be used to accurately model the decay of β-lactams by PAA in surface water matrix and only slightly overestimate the decay in wastewater matrix. Results of this study indicate that the oxidative transformation of β-lactams by PAA can be expected under appropriate wastewater treatment conditions. Copyright © 2017. Published by Elsevier Ltd.

  15. Methane production from formate, acetate and H2/CO2; focusing on kinetics and microbial characterization

    DEFF Research Database (Denmark)

    Pan, Xiaofang; Angelidaki, Irini; Alvarado-Morales, Merlin

    2016-01-01

    For evaluating the methanogenesis from typical methanogenic precursors (formate, acetate and H-2/CO2), CH4 production kinetics were investigated at 37 +/- 1 degrees C in batch anaerobic digestion tests and stimulated by modified Gompertz model. The results showed that maximum methanation rate from...... formate, acetate and H-2/CO2 were 19.58 +/- 0.49, 42.65 +/- 1.17 and 314.64 +/- 3.58 N mL/gVS/d in digested manure system and 6.53 +/- 0.31, 132.04 +/- 3.96 and 640.16 +/- 19.92 N mL/gVS/d in sewage sludge system during second generation incubation. Meanwhile the model could not fit well in granular...... sludge system, while the rate of formate methanation was faster than from H-2/CO2 and acetate. Considering both the kinetic results and microbial assay we could conclude that H-2/CO2 methanation was the fastest methanogenic step in digested manure and sewage sludge system with Methanomicrobiales...

  16. Kinetic study of the thermal hydrolysis of Agave salmiana for mezcal production.

    Science.gov (United States)

    Garcia-Soto, M J; Jimenez-Islas, H; Navarrete-Bolanos, J L; Rico-Martinez, R; Miranda-Lopez, R; Botello-Alvarez, J E

    2011-07-13

    The kinetics of the thermal hydrolysis of the fructans of Agave salmiana were determined during the cooking step of mezcal production in a pilot autoclave. Thermal hydrolysis was achieved at different temperatures and cooking times, ranging from 96 to 116 °C and from 20 to 80 h. A simple kinetic model of the depolymerization of fructans to monomers and other reducing sugars and of the degradation of reducing sugars to furans [principally 5-(hydroxymethyl)furfural, HMF] was developed. From this model, the rate constants of the reactions were calculated, as well as the pre-exponential factors and activation energies of the Arrhenius equation. The model was found to fit the experimental data well. The tradeoff between a maximum fructan hydrolysis and a critical furan concentration in allowing for the best ethanol yield during fermentation was investigated. The results indicated that the thermal hydrolysis of agave was optimal, from the point of view of ethanol yield in the ensuing fermentation, in the temperature range of 106-116 °C and the cooking range time of 6-14 h. The optimal conditions corresponded to a fructan hydrolysis of 80%, producing syrups with furan and reducing sugar concentrations of 1 ± 0.1 and 110 ± 10 g/L, respectively.

  17. Kinetics of the hydrogen production reaction in a copper-chlorine water splitting plant

    International Nuclear Information System (INIS)

    Zamfirescu, C.; Naterer, G.F.; Dincer, I.

    2009-01-01

    The exothermic reaction of HCl with particulate Cu occurs during hydrogen production step in the thermochemical copper-chlorine (Cu-Cl) water splitting cycle. In this paper, this chemical reaction is modeled kinetically, and a parametric study is performed to determine the influences of particle size, temperature and molar ratios on the reaction kinetics. It is determined that the residence time of copper particles varies between 10 and 100 s, depending on the operating conditions. The hydrogen conversion at equilibrium varies between 55 and 85%, depending on the reaction temperature. The heat flux at the particle surface, caused by the exothermic enthalpy of reaction, reaches about 3,000 W/m 2 when the particle shrinks to 0.1% from its initial size. A numerical algorithm is developed to solve the moving boundary Stefan problem with a chemical reaction. It predicts the shrinking of copper particles based on the hypothesis that the chemical reaction and heat transfer are decoupled. The model allows for estimation of the temperature of the copper particle, assumed spherical, in the radial direction. The maximum temperature at the interface is higher than the melting point of CuCl by 10-50 o C, depending on the assumed operating conditions. (author)

  18. The third data release of the Kilo-Degree Survey and associated data products

    Science.gov (United States)

    de Jong, Jelte T. A.; Kleijn, Gijs A. Verdoes; Erben, Thomas; Hildebrandt, Hendrik; Kuijken, Konrad; Sikkema, Gert; Brescia, Massimo; Bilicki, Maciej; Napolitano, Nicola R.; Amaro, Valeria; Begeman, Kor G.; Boxhoorn, Danny R.; Buddelmeijer, Hugo; Cavuoti, Stefano; Getman, Fedor; Grado, Aniello; Helmich, Ewout; Huang, Zhuoyi; Irisarri, Nancy; La Barbera, Francesco; Longo, Giuseppe; McFarland, John P.; Nakajima, Reiko; Paolillo, Maurizio; Puddu, Emanuella; Radovich, Mario; Rifatto, Agatino; Tortora, Crescenzo; Valentijn, Edwin A.; Vellucci, Civita; Vriend, Willem-Jan; Amon, Alexandra; Blake, Chris; Choi, Ami; Conti, Ian Fenech; Gwyn, Stephen D. J.; Herbonnet, Ricardo; Heymans, Catherine; Hoekstra, Henk; Klaes, Dominik; Merten, Julian; Miller, Lance; Schneider, Peter; Viola, Massimo

    2017-08-01

    Context. The Kilo-Degree Survey (KiDS) is an ongoing optical wide-field imaging survey with the OmegaCAM camera at the VLT Survey Telescope. It aims to image 1500 square degrees in four filters (ugri). The core science driver is mapping the large-scale matter distribution in the Universe, using weak lensing shear and photometric redshift measurements. Further science cases include galaxy evolution, Milky Way structure, detection of high-redshift clusters, and finding rare sources such as strong lenses and quasars. Aims: Here we present the third public data release and several associated data products, adding further area, homogenized photometric calibration, photometric redshifts and weak lensing shear measurements to the first two releases. Methods: A dedicated pipeline embedded in the Astro-WISE information system is used for the production of the main release. Modifications with respect to earlier releases are described in detail. Photometric redshifts have been derived using both Bayesian template fitting, and machine-learning techniques. For the weak lensing measurements, optimized procedures based on the THELI data reduction and lensfit shear measurement packages are used. Results: In this third data release an additional 292 new survey tiles (≈300 deg2) stacked ugri images are made available, accompanied by weight maps, masks, and source lists. The multi-band catalogue, including homogenized photometry and photometric redshifts, covers the combined DR1, DR2 and DR3 footprint of 440 survey tiles (44 deg2). Limiting magnitudes are typically 24.3, 25.1, 24.9, 23.8 (5σ in a 2'' aperture) in ugri, respectively, and the typical r-band PSF size is less than 0.7''. The photometric homogenization scheme ensures accurate colours and an absolute calibration stable to ≈2% for gri and ≈3% in u. Separately released for the combined area of all KiDS releases to date are a weak lensing shear catalogue and photometric redshifts based on two different machine

  19. Implementing a Brand Strategy for a New Product: Releasing a New Product in a Multinational Company

    OpenAIRE

    Alexandra ION

    2011-01-01

    The present paper focuses on the issue of using marketing intruments (like innovation, creativity, revitalization) in multinational companies like Coca Cola. The research is about identifying the right options and marketing strategies, for implementing a new and healthy product on the market, and studying the consumer behavior, regarding the subject. In conclusion, this product could be a chance for this company to improve image and to take benefit by increasing the number of consumers.

  20. Fission product release profiles from spherical HTR fuel elements at accident temperatures

    International Nuclear Information System (INIS)

    Schenk, W.; Pitzer, D.; Nabielek, H.

    1986-10-01

    A total of 22 fuel elements with modern TRISO particles has been tested in the temperature range 1500-2500 0 C. Additionally, release profiles of iodine and other isotopes have been obtained with seven UO 2 samples at 1400-1800 0 C. For heating times up to 100 hours at the maximum temperature, the following results are pertinent to HTR accident conditions: Ag 110 m is the only fission products to be released at 1200-1600 0 C by diffusion through intact SiC, but it is of low significance in accident assessments; cesium, iodine, strontium, and noble gas releases up to 1600 0 C are solely due to various forms of contamination; at 1700-1800 0 C, corrosion induced SiC defects cause the release of Cs, Sr, I/Xe/Kr; above 2000 0 C, thermal decomposition of the silicon carbide layer sets in while pyrocarbons still remain intact. Around 1600 0 C, the accident specific contribution of cesium, strontium, iodine, and noble gases is negligible. (orig./HP) [de

  1. Evidence of arsenic release promoted by disinfection by-products within drinking-water distribution systems.

    Science.gov (United States)

    Andra, Syam S; Makris, Konstantinos C; Botsaris, George; Charisiadis, Pantelis; Kalyvas, Harris; Costa, Costas N

    2014-02-15

    Changes in disinfectant type could trigger a cascade of reactions releasing pipe-anchored metals/metalloids into finished water. However, the effect of pre-formed disinfection by-products on the release of sorbed contaminants (arsenic-As in particular) from drinking water distribution system pipe scales remains unexplored. A bench-scale study using a factorial experimental design was performed to evaluate the independent and interaction effects of trihalomethanes (TTHM) and haloacetic acids (HAA) on arsenic (As) release from either scales-only or scale-biofilm conglomerates (SBC) both anchored on asbestos/cement pipe coupons. A model biofilm (Pseudomonas aeruginosa) was allowed to grow on select pipe coupons prior experimentation. Either TTHM or HAA individual dosing did not promote As release from either scales only or SBC, detecting water. In the case of scales-only coupons, the combination of the highest spike level of TTHM and HAA significantly (pwater in pipe networks remains to be investigated in the field. Copyright © 2013 Elsevier B.V. All rights reserved.

  2. Kinetics of selenium release in mine waste from the Meade Peak Phosphatic Shale, Phosphoria Formation, Wooley Valley, Idaho, USA

    Science.gov (United States)

    Stillings, Lisa L.; Amacher, Michael C.

    2010-01-01

    Phosphorite from the Meade Peak Phosphatic Shale member of the Permian Phosphoria Formation has been mined in southeastern Idaho since 1906. Dumps of waste rock from mining operations contain high concentrations of Se which readily leach into nearby streams and wetlands. While the most common mineralogical residence of Se in the phosphatic shale is elemental Se, Se(0), Se is also an integral component of sulfide phases (pyrite, sphalerite and vaesite–pyritess) in the waste rock. It may also be present as adsorbed selenate and/or selenite, and FeSe2 and organo-selenides.Se release from the waste rock has been observed in field and laboratory experiments. Release rates calculated from waste rock dump and column leachate solutions describe the net, overall Se release from all of the possible sources of Se listed above. In field studies, Se concentration in seepage water (pH 7.4–7.8) from the Wooley Valley Unit 4 dump ranges from 3600 µg/L in May to 10 µg/L by Sept. Surface water flow, Q, from the seep also declines over the summer, from 2 L/s in May to 0.03 L/s in Sept. Se flux ([Se] ⁎ Q) reaches a steady-state of Laboratory experiments were performed with the waste shale in packed bed reactors; residence time varied from 0.09 to 400 h and outlet pH ∼ 7.5. Here, Se concentration increased with increasing residence time and release was modeled with a first order reaction with k = 2.19e−3 h− 1 (19.2 yr− 1).Rate constants reported here fall within an order of magnitude of reported rate constants for oxidation of Se(0) formed by bacterial precipitation. This similarity among rate constants from both field and laboratory studies combined with the direct observation of Se(0) in waste shales of the Phosphoria Formation suggests that oxidation of Se(0) may control steady-state Se concentration in water draining the Wooley Valley waste dump.

  3. Absorption kinetics and steady-state plasma concentrations of theophylline following therapeutic doses of two sustained-release preparations

    DEFF Research Database (Denmark)

    Andersen, O; Nielsen, M K; Eriksen, P B

    1983-01-01

    Ten healthy volunteers received two sustained-release preparations as a single and multiple dose regimen in an open crossover study. Plasma theophylline concentrations were measured by an enzyme immunoassay. The limited fluctuation of the theophylline levels at steady state, with twice daily...... formulation, whereas this was not the case for the other (r = 0.27 and 0.49). The daily dose necessary to keep the plasma concentration within the therapeutic range of 55-110 mumole/liter varied from 7.9 to 22.9 mg/kg. Only mild side effects were recorded, but they were not correlated to the plasma...... theophylline concentration....

  4. Preparation and Drug-Release Kinetics of Porous Poly(L-lactic acid)/Rifampicin Blend Particles

    OpenAIRE

    Takashi Sasaki; Hiroaki Matsuura; Kazuki Tanaka

    2014-01-01

    Porous polymer spheres are promising materials as carriers for controlled drug release. As a new drug-carrier material, blend particles composed of poly(L-lactic acid) (PLLA) and rifampicin were developed using the freeze-drying technique. The blend particles exhibit high porosity with a specific surface area of 10–40 m2 g−1. Both the size and porosity of the particles depend on the concentration of the original solution and on the method of freezing. With respect to the latter, we used the d...

  5. Growth and production kinetics of human x mouse and mouse hybridoma cells at reduced temperature and serum content.

    Science.gov (United States)

    Borth, N; Heider, R; Assadian, A; Katinger, H

    1992-09-01

    The growth and production kinetics of a mouse hybridoma cell line and a human-mouse heterohybridoma were analyzed under conditions of reduced temperature and serum content. The mouse hybridoma P24 had a constant cell specific production rate and RNA content, while the heterohybridoma 3D6-LC4 showed growth associated production kinetics and an increased RNA content at higher growth rates. This behaviour of 3D6-LC4 cells can be explained by the unusual cell cycle kinetics of this line, which can be arrested in any phase under growth limiting conditions, so that a low growth rate does not result in a greater portion of high producing G1-phase cells. Substrate limitation changes the cell cycle distribution of this cell line to a greater extent than low temperature or serum content, which indicates that this stress factor exerts a greater physiological control than assumed.

  6. Heterogeneous reaction of particulate chlorpyrifos with NO3 radicals: Products, pathways, and kinetics

    Science.gov (United States)

    Li, Nana; Zhang, Peng; Yang, Bo; Shu, Jinian; Wang, Youfeng; Sun, Wanqi

    2014-08-01

    Chlorpyrifos is a typical chlorinated organophosphorus pesticide. The heterogeneous reaction of chlorpyrifos particles with NO3 radicals was investigated using a vacuum ultraviolet photoionization aerosol time-of-flight mass spectrometer (VUV-ATOFMS) and a real-time atmospheric gas analysis mass spectrometer. Chlorpyrifos oxon, 3,5,6-trichloro-2-pyridinol, O,O-diethyl O-hydrogen phosphorothioate, O,O-diethyl ester thiophosphoric acid, diethyl hydrogen phosphate and a phosphinyl disulfide compound were identified as the main degradation products. The heterogeneous reaction pathways were proposed and their kinetic processes were investigated via a mixed-phase relative rate method. The observed effective rate constant is 3.4 ± 0.2 × 10-12 cm3 molecule-1 s-1.

  7. Kinetic simulation of neutron production in a deuterium z-pinch

    International Nuclear Information System (INIS)

    Mostrom, C.; Stygar, William A.; Thoma, Carsten; Welch, Dale Robert; Clark, R.E.; Leeper, Ramon Joe; Rose, David V.

    2010-01-01

    We have found computationally that, at sufficiently high currents, half of the neutrons produced by a deuterium z pinch are thermonuclear in origin. Early experiments below 1-MA current found that essentially all of the neutrons produced by a deuterium pinch are not thermonuclear, but are initiated by an instability that creates beam-target neutrons. Many subsequent authors have supported this result while others have claimed that pinch neutrons are thermonuclear. To resolve this issue, we have conducted fully kinetic, collisional, and electromagnetic simulations of the complete time evolution of a deuterium pinch. We find that at 1-MA pinch currents, most of the neutrons are, indeed, beam-target in origin. At much higher current, half of the neutrons are thermonuclear and half are beam-target driven by instabilities that produce a power law fall off in the ion energy distribution function at large energy. The implications for fusion energy production with such pinches are discussed.

  8. Results of fission product release from intermediate-scale MCCI [molten core-concrete interaction] tests

    International Nuclear Information System (INIS)

    Spencer, B.W.; Thompson, D.H.; Fink, J.K.; Gunther, W.H.; Sehgal, B.R.

    1988-01-01

    A program of reactor-material molten core-concrete interaction (MCCI) tests and related analyses are under way at Argonne National Laboratory under sponsorship of the Electric Power Research Institute (EPRI). The particular objective of these tests is to provide data pertaining to the release of nonvolatile fission products such as La, Ba, and Sr, plus other aerosol materials, from the coupled thermal-hydraulic and chemical processes of the MCCI. The first stages of the program involving small and intermediate-scale tests have been completed. Three small-scale tests (/approximately/5 kg corium) and nine intermediate-scale tests (/approximately/30 kg corium) were performed between September 1985 and September 1987. Real reactor materials were used in these tests. Sustained internal heat generation at nominally 1 kW per kg of melt was provided by direct electrical heating of the corium mixture. MCCI tests were performed with both fully and partially oxidized corium mixtures that contained a variety of nonradioactive materials such as La 2 O 3 , BaO, and SrO to represent fission products. Both limestone/common sand and basaltic concrete basemats were used. The system was instrumented for characterization of the thermal hydraulic, chemical, gas release, and aerosol release processes

  9. Radioecological studies of activation products released from a nuclear power plant into the marine environment

    Energy Technology Data Exchange (ETDEWEB)

    Nilsson, M.; Mattsson, S.; Holm, E.

    1984-01-01

    The Barseback nuclear power plant, located on the Oresund sound between Denmark and Sweden, consists of two boiling water reactors. The release of radionuclides, mainly activation products, is quite low during normal operation. During the summer, when annual overhaul and partial refuelling take place, the discharge is much higher. Samples of seaweeds and crustaceans collected along the coast were analyzed for radionuclides. Seaweeds (Fucus vesiculosus, F. Serratus, Ascophyllum nodosum and Cladophora glomerata) and crustaceans (Idothea and Gammarus) proved to be excellent bioindicators for radioactive corrosion products released from the nuclear power plant into the marine environment. These bioindicators have been used to map the spatial and temporal distribution of the released radioactivity. The activity has been followed up to 150 km from the power plant, and the decrease in activity concentration in the bioindicators with distance can be expressed by a power function. The variation with time of activity concentration reflects the amount of activity discharged from the power plant, with good resolution in time. The bioindicators exhibit different uptake patterns of the radionuclides detected. The crustacean Idothea showed variations in the Co/sup 60/ activity concentration between winter and summer. 9 references, 12 figures, 2 tables.

  10. Online characterization of nano-aerosols released by commercial spray products using SMPS–ICPMS coupling

    Energy Technology Data Exchange (ETDEWEB)

    Losert, Sabrina; Hess, Adrian [Empa Swiss Federal Laboratories for Materials Science and Technology, Laboratory for Analytical Chemistry (Switzerland); Ilari, Gabriele [Empa Swiss Federal Laboratories for Materials Science and Technology, Electron Microscopy Center (Switzerland); Goetz, Natalie von, E-mail: natalie.von.goetz@chem.ethz.ch; Hungerbuehler, Konrad [ETH Zürich Swiss Federal Institute of Technology Zürich, Institute for Chemical and Bioengineering (Switzerland)

    2015-07-15

    Nanoparticle-containing sprays are a critical class of consumer products, since human exposure may occur by inhalation of nanoparticles (NP) in the generated aerosols. In this work, the suspension and the released aerosol of six different commercially available consumer spray products were analyzed. Next to a broad spectrum of analytical methods for the characterization of the suspension, a standardized setup for the analysis of aerosol has been used. In addition, a new online coupling technique (SMPS–ICPMS) for the simultaneous analysis of particle size and elemental composition of aerosol particles has been applied. Results obtained with this new method were confirmed by other well-established techniques. Comparison of particles in the original suspensions and in the generated aerosol showed that during spraying single particles of size less than 20 nm had been formed, even though in none of the suspensions particles of size less than 280 nm were present (Aerosol size range scanned: 7–300 nm). Both pump sprays and propellant gas sprays were analyzed and both released particles in the nm size range. Also, both water-based and organic solvent-based sprays released NP. However, a trend was observed that spraying an aqueous suspension contained in a pump spray dispenser after drying resulted in bigger agglomerates than spraying organic suspensions in propellant gas dispensers.

  11. Soil Moisture Active Passive Mission L4_C Data Product Assessment (Version 2 Validated Release)

    Science.gov (United States)

    Kimball, John S.; Jones, Lucas A.; Glassy, Joseph; Stavros, E. Natasha; Madani, Nima; Reichle, Rolf H.; Jackson, Thomas; Colliander, Andreas

    2016-01-01

    The SMAP satellite was successfully launched January 31st 2015, and began acquiring Earth observation data following in-orbit sensor calibration. Global data products derived from the SMAP L-band microwave measurements include Level 1 calibrated and geolocated radiometric brightness temperatures, Level 23 surface soil moisture and freezethaw geophysical retrievals mapped to a fixed Earth grid, and model enhanced Level 4 data products for surface to root zone soil moisture and terrestrial carbon (CO2) fluxes. The post-launch SMAP mission CalVal Phase had two primary objectives for each science product team: 1) calibrate, verify, and improve the performance of the science algorithms, and 2) validate accuracies of the science data products as specified in the L1 science requirements. This report provides analysis and assessment of the SMAP Level 4 Carbon (L4_C) product pertaining to the validated release. The L4_C validated product release effectively replaces an earlier L4_C beta-product release (Kimball et al. 2015). The validated release described in this report incorporates a longer data record and benefits from algorithm and CalVal refinements acquired during the SMAP post-launch CalVal intensive period. The SMAP L4_C algorithms utilize a terrestrial carbon flux model informed by SMAP soil moisture inputs along with optical remote sensing (e.g. MODIS) vegetation indices and other ancillary biophysical data to estimate global daily net ecosystem CO2 exchange (NEE) and component carbon fluxes for vegetation gross primary production (GPP) and ecosystem respiration (Reco). Other L4_C product elements include surface (10 cm depth) soil organic carbon (SOC) stocks and associated environmental constraints to these processes, including soil moisture and landscape freeze/thaw (FT) controls on GPP and respiration (Kimball et al. 2012). The L4_C product encapsulates SMAP carbon cycle science objectives by: 1) providing a direct link between terrestrial carbon fluxes and

  12. Experimental study of the reactions of limonene with OH and OD radicals: kinetics and products.

    Science.gov (United States)

    Braure, Tristan; Bedjanian, Yuri; Romanias, Manolis N; Morin, Julien; Riffault, Véronique; Tomas, Alexandre; Coddeville, Patrice

    2014-10-09

    The kinetics of the reactions of limonene with OH and OD radicals has been studied using a low-pressure flow tube reactor coupled with a quadrupole mass spectrometer: OH + C10H16 → products (1), OD + C10H16 → products (2). The rate constants of the title reactions were determined using four different approaches: either monitoring the kinetics of OH (OD) radicals or limonene consumption in excess of limonene or of the radicals, respectively (absolute method), and by the relative rate method using either the reaction OH (OD) + Br2 or OH (OD) + DMDS (dimethyl disulfide) as the reference one and following HOBr (DOBr) formation or DMDS and limonene consumption, respectively. As a result of the absolute and relative measurements, the overall rate coefficients, k1 = (3.0 ± 0.5) × 10(-11) exp((515 ± 50)/T) and k2 = (2.5 ± 0.6) × 10(-11) exp((575 ± 60)/T) cm(3) molecule(-1) s(-1), were determined at a pressure of 1 Torr of helium over the temperature ranges 220-360 and 233-353 K, respectively. k1 was found to be pressure independent over the range 0.5-5 Torr. There are two possible pathways for the reaction between OH (OD) and limonene: addition of the radical to one of the limonene double bonds (reactions 1a and 2a ) and abstraction of a hydrogen atom (reactions 1b and 2b ), resulting in the formation of H2O (HOD). Measurements of the HOD yield as a function of temperature led to the following branching ratio of the H atom abstraction channel: k2b/k2 = (0.07 ± 0.03) × exp((460 ± 140)/T) for T = (253-355) K.

  13. Process optimization and analysis of product inhibition kinetics of crude glycerol fermentation for 1,3-Dihydroxyacetone production.

    Science.gov (United States)

    Dikshit, Pritam Kumar; Padhi, Susant Kumar; Moholkar, Vijayanand S

    2017-11-01

    In present study, statistical optimization of biodiesel-derived crude glycerol fermentation to DHA by immobilized G. oxydans cells over polyurethane foam is reported. Effect of DHA (product) inhibition on crude glycerol fermentation was analyzed using conventional biokinetic models and new model that accounts for both substrate and product inhibition. Optimum values of fermentation parameters were: pH=4.7, temperature=31°C, initial substrate concentration=20g/L. At optimum conditions, DHA yield was 89% (17.83g/L). Effect of product inhibition on fermentation was trivial for DHA concentrations ≤30g/L. At higher concentrations (≥50g/L), kinetics and yield of fermentation showed marked reduction with sharp drop in V max and K S values. Inhibition effect was more pronounced for immobilized cells due to restricted transport of fermentation mixture across polyurethane foam. Retention of fermentation mixture in immobilized matrix resulted in higher localized DHA concentration that possibly enhanced inhibition effect. Copyright © 2017 Elsevier Ltd. All rights reserved.

  14. Fission product release during MCCI. CEC nuclear safety program: MCCI project

    Energy Technology Data Exchange (ETDEWEB)

    Cenerino, G [CEA Centre d` Etudes Nucleaires de Fontenay-aux-Roses, 92 (France). Inst. de Protection et de Surete Nucleaire; Cordfunke, E H.P. [Netherlands Energy Research Foundation (ECN), Petten (Netherlands); Hunterlaar, M E [Netherlands Energy Research Foundation (ECN), Petten (Netherlands)

    1995-01-01

    The assessment of the consequences of severe accidents in nuclear reactors involving molten core-concrete interactions (MCCls) requires estimates of the quantities and physicochemical forms of the radioactive species released from the melt into the cavity atmosphere. Such estimates in turn require a detailed knowledge of the complex chemical interactions which would occur between the fission products, fuel and the components of the core structural materials and the concrete. In recent years, effort has been put into the thermodynamic characterization of these processes. The results of such studies are important for predicting several aspects of MCCls, including: 1. The release of species by vaporization; 2. the extent of concrete penetration: a. The melt solidus and liquidus temperatures, which in turn affect the heat transfer processes and hence tile predictions of the melt temperature and the onset of solidification, b. the amounts of the solid and liquid phases and the respective compositions, which determines the viscosity of the melt, and c. the composition of the crust formed following the addition of water to quench the interaction. d. the distribution of fission products among metallic and oxidic phases. This SOAR is devoted to thermochemical calculations in the context of MCCI where most fission products and the metallic components of the melt are transferred into an oxidic form sooner or later. Calculations on fission product release from a molten pool without MCCI are underway in the source term project of the CEC-RCA. The following conditions have to be taken into account in order to be able to perform reliable thermodynamic calculations. (orig./HP).

  15. Fission product release during MCCI. CEC nuclear safety program: MCCI project

    International Nuclear Information System (INIS)

    Cenerino, G.; Hunterlaar, M.E.

    1995-01-01

    The assessment of the consequences of severe accidents in nuclear reactors involving molten core-concrete interactions (MCCls) requires estimates of the quantities and physicochemical forms of the radioactive species released from the melt into the cavity atmosphere. Such estimates in turn require a detailed knowledge of the complex chemical interactions which would occur between the fission products, fuel and the components of the core structural materials and the concrete. In recent years, effort has been put into the thermodynamic characterization of these processes. The results of such studies are important for predicting several aspects of MCCls, including: 1. The release of species by vaporization; 2. the extent of concrete penetration: a. The melt solidus and liquidus temperatures, which in turn affect the heat transfer processes and hence tile predictions of the melt temperature and the onset of solidification, b. the amounts of the solid and liquid phases and the respective compositions, which determines the viscosity of the melt, and c. the composition of the crust formed following the addition of water to quench the interaction. d. the distribution of fission products among metallic and oxidic phases. This SOAR is devoted to thermochemical calculations in the context of MCCI where most fission products and the metallic components of the melt are transferred into an oxidic form sooner or later. Calculations on fission product release from a molten pool without MCCI are underway in the source term project of the CEC-RCA. The following conditions have to be taken into account in order to be able to perform reliable thermodynamic calculations. (orig./HP)

  16. Release of nanomaterials from consumer products and implications for consumer exposure assessment

    DEFF Research Database (Denmark)

    Mackevica, Aiga

    attention, and the data currently available in the literature is scarce. Most studies are addressing only a narrow range of product categories and a few NM types, having experimental setups that are rarely comparable from study to study. Moreover, the analytical techniques applied for release testing......, data from literature and online databases was used to obtain an overview of what nanoproducts are available on the EU market, and which nanoproducts have been experimentally tested for their potential NM release. Specific focus was placed on evaluating suitable analytical methods for NM quantification...... and characterization. The findings showed that single particle inductively coupled plasma mass spectrometry (spICP-MS) in combination with other methods is a well suited analytical technique that can provide extensive NM characterization, such as mass and number concentration, and size distribution of NMs. Then...

  17. Aroma Precursors in Grapes and Wine: Flavor Release during Wine Production and Consumption.

    Science.gov (United States)

    Parker, Mango; Capone, Dimitra L; Francis, I Leigh; Herderich, Markus J

    2018-03-14

    Pioneering investigations into precursors of fruity and floral flavors established the importance of terpenoid and C 13 -norisoprenoid glycosides to the flavor of aromatic wines. Nowadays flavor precursors in grapes and wine are known to be structurally diverse, encompassing glycosides, amino acid conjugates, odorless volatiles, hydroxycinnamic acids, and many others. Flavor precursors mainly originate in the grape berry but also from oak or other materials involved in winemaking. Flavors are released from precursors during crushing and subsequent production steps by enzymatic and nonenzymatic transformations, via microbial glycosidases, esterases, C-S lyases, and decarboxylases, and through acid-catalyzed hydrolysis and chemical rearrangements. Flavors can also be liberated from glycosides and amino acid conjugates by oral microbiota. Hence, it is increasingly likely that flavor precursors contribute to retronasal aroma formation through in-mouth release during consumption, prompting a shift in focus from identifying aroma precursors in grapes to understanding aroma precursors present in bottled wine.

  18. Fission Fragment Mass Distributions and Total Kinetic Energy Release of 235-Uranium and 238-Uranium in Neutron-Induced Fission at Intermediate and Fast Neutron Energies

    Energy Technology Data Exchange (ETDEWEB)

    Duke, Dana Lynn [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-11-12

    This Ph.D. dissertation describes a measurement of the change in mass distributions and average total kinetic energy (TKE) release with increasing incident neutron energy for fission of 235U and 238U. Although fission was discovered over seventy-five years ago, open questions remain about the physics of the fission process. The energy of the incident neutron, En, changes the division of energy release in the resulting fission fragments, however, the details of energy partitioning remain ambiguous because the nucleus is a many-body quantum system. Creating a full theoretical model is difficult and experimental data to validate existing models are lacking. Additional fission measurements will lead to higher-quality models of the fission process, therefore improving applications such as the development of next-generation nuclear reactors and defense. This work also paves the way for precision experiments such as the Time Projection Chamber (TPC) for fission cross section measurements and the Spectrometer for Ion Determination in Fission (SPIDER) for precision mass yields.

  19. Kinetic study of biosurfactant production by Bacillus subtilis LAMI005 grown in clarified cashew apple juice.

    Science.gov (United States)

    de Oliveira, Darlane Wellen Freitas; França, Italo Waldimiro Lima; Félix, Anne Kamilly Nogueira; Martins, João Jeferson Lima; Giro, Maria Estela Aparecida; Melo, Vânia Maria M; Gonçalves, Luciana Rocha Barros

    2013-01-01

    In this work a low cost medium for the production of a biosurfactant by Bacillus subtilis LAMI005 and the kinetics of surfactin production considering the effect of initial substrate concentration were investigated. First, cashew apple juice supplementation for optimal production of biosurfactant by B. subtilis LAMI005 was studied. The medium formulated with clarified cashew apple juice and distilled water, supplemented with 1.0 g/L of (NH(4))(2)SO(4), proved to be the best among the nutrients evaluated. The crude biosurfactant had the ability to decrease the surface tension of water to 30 dyne/cm, with a critical micelle concentration (CMC) of 63.0 mg/L. Emulsification experiments indicated that this biosurfactant effectively emulsified kerosene (IE(24)=67%) and soybean oil (IE(24)=64%). Furthermore, the emulsion stability was always very high. It was shown by biochemical analysis, IR spectra, that there is no qualitative differences in the composition of the crude biosurfactant from a standard sample of surfactin from B. subtilis. Copyright © 2012 Elsevier B.V. All rights reserved.

  20. Product Characterization and Kinetics of Biomass Pyrolysis in a Three-Zone Free-Fall Reactor

    Directory of Open Access Journals (Sweden)

    Natthaya Punsuwan

    2014-01-01

    Full Text Available Pyrolysis of biomass including palm shell, palm kernel, and cassava pulp residue was studied in a laboratory free-fall reactor with three separated hot zones. The effects of pyrolysis temperature (250–1050°C and particle size (0.18–1.55 mm on the distribution and properties of pyrolysis products were investigated. A higher pyrolysis temperature and smaller particle size increased the gas yield but decreased the char yield. Cassava pulp residue gave more volatiles and less char than those of palm kernel and palm shell. The derived solid product (char gave a high calorific value of 29.87 MJ/kg and a reasonably high BET surface area of 200 m2/g. The biooil from palm shell is less attractive to use as a direct fuel, due to its high water contents, low calorific value, and high acidity. On gas composition, carbon monoxide was the dominant component in the gas product. A pyrolysis model for biomass pyrolysis in the free-fall reactor was developed, based on solving the proposed two-parallel reactions kinetic model and equations of particle motion, which gave excellent prediction of char yields for all biomass precursors under all pyrolysis conditions studied.

  1. Photodegradation of malachite green under simulated and natural irradiation: kinetics, products, and pathways.

    Science.gov (United States)

    Yong, Li; Zhanqi, Gao; Yuefei, Ji; Xiaobin, Hu; Cheng, Sun; Shaogui, Yang; Lianhong, Wang; Qingeng, Wang; Die, Fang

    2015-03-21

    In this work photodegradation rates and pathways of malachite green were studied under simulated and solar irradiation with the goal of assessing the potential of photolysis as a removal mechanism in real aquatic environment. Factors influencing the photodegradation process were investigated, including pH, humic acid, Fe(2+), Ca(2+), HCO3(-), and NO3(-), of which favorable conditions were optimized by the orthogonal array design under simulated sunlight irradiation in the presence of dissolved oxygen. The degradation processes of malachite green conformed to pseudo first-order kinetics and their degradation rate constants were between 0.0062 and 0.4012 h(-1). Under solar irradiation, the decolorization efficiency of most tests can reach almost 100%, and relatively thorough mineralization could be observed. Forty degradation products were detected by liquid chromatography-mass spectrometry, and thirteen small molecular products were identified by gas chromatography-mass spectrometry. Based on the analyses of the degradation products and calculation of the frontier electron density, the pathways were proposed: decomposition of conjugated structure, N-demethylation reactions, hydroxyl addition reactions, the removal of benzene ring, and the ring-opening reaction. This study has provided a reference, both for photodegradation of malachite green and future safety applications and predictions of decontamination of related triphenylmethane dyes under real conditions. Copyright © 2014 Elsevier B.V. All rights reserved.

  2. Medium Optimization and Fermentation Kinetics for κ-Carrageenase Production by Thalassospira sp. Fjfst-332

    Directory of Open Access Journals (Sweden)

    Juanjuan Guo

    2016-11-01

    Full Text Available Effective degradation of κ-carrageenan by isolated Thalassospira sp. fjfst-332 is reported for the first time in this paper. It was identified by 16S rDNA sequencing and morphological observation using Transmission Electron Microscopy (TEM. Based on a Plackett–Burman design for significant variables, Box–Behnken experimental design and response surface methodology were used to optimize the culture conditions. Through statistical optimization, the optimum medium components were determined as follows: 2.0 g/L κ-carrageenan, 1.0 g/L yeast extract, 1.0 g/L FOS, 20.0 g/L NaCl, 2.0 g/L NaNO3, 0.5 g/L MgSO4·7H2O, 0.1 g/L K2HPO4, and 0.1 g/L CaCl2. The highest activity exhibited by Thalassospira sp. fjfst-332 was 267 U/mL, which makes it the most vigorous wild bacterium for κ-carrageenan production. In order to guide scaled-up production, two empirical models—the logistic equation and Luedeking–Piretequation—were proposed to predict the strain growth and enzyme production, respectively. Furthermore, we report the fermentation kinetics and every empirical equation of the coefficients (α, β, X0, Xm and μm for the two models, which could be used to design and optimize industrial processes.

  3. Quantum-kinetic modeling of electron release in low-energy surface collisions of atoms and molecules

    Energy Technology Data Exchange (ETDEWEB)

    Marbach, Johannes

    2012-09-20

    In this work we present a theoretical description of electron release in the collision of atomic and molecular projectiles with metallic and especially dielectric surfaces. The associated electron yield, the secondary electron emission coefficient, is an important input parameter for numerical simulations of dielectric barrier discharges and other bounded low-temperature gas discharges. The available reference data for emission coefficients is, however, very sparse and often uncertain, especially for molecular projectiles. With the present work we aim to contribute to the filling of these gaps by providing a flexible and easy-to-use model that allows for a convenient calculation of the emission coefficient and related quantities for a wide range of projectile-surface systems and the most dominant reaction channels.

  4. Quantum-kinetic modeling of electron release in low-energy surface collisions of atoms and molecules

    International Nuclear Information System (INIS)

    Marbach, Johannes

    2012-01-01

    In this work we present a theoretical description of electron release in the collision of atomic and molecular projectiles with metallic and especially dielectric surfaces. The associated electron yield, the secondary electron emission coefficient, is an important input parameter for numerical simulations of dielectric barrier discharges and other bounded low-temperature gas discharges. The available reference data for emission coefficients is, however, very sparse and often uncertain, especially for molecular projectiles. With the present work we aim to contribute to the filling of these gaps by providing a flexible and easy-to-use model that allows for a convenient calculation of the emission coefficient and related quantities for a wide range of projectile-surface systems and the most dominant reaction channels.

  5. Implementation of a Thermodynamic Solver within a Computer Program for Calculating Fission-Product Release Fractions

    Science.gov (United States)

    Barber, Duncan Henry

    During some postulated accidents at nuclear power stations, fuel cooling may be impaired. In such cases, the fuel heats up and the subsequent increased fission-gas release from the fuel to the gap may result in fuel sheath failure. After fuel sheath failure, the barrier between the coolant and the fuel pellets is lost or impaired, gases and vapours from the fuel-to-sheath gap and other open voids in the fuel pellets can be vented. Gases and steam from the coolant can enter the broken fuel sheath and interact with the fuel pellet surfaces and the fission-product inclusion on the fuel surface (including material at the surface of the fuel matrix). The chemistry of this interaction is an important mechanism to model in order to assess fission-product releases from fuel. Starting in 1995, the computer program SOURCE 2.0 was developed by the Canadian nuclear industry to model fission-product release from fuel during such accidents. SOURCE 2.0 has employed an early thermochemical model of irradiated uranium dioxide fuel developed at the Royal Military College of Canada. To overcome the limitations of computers of that time, the implementation of the RMC model employed lookup tables to pre-calculated equilibrium conditions. In the intervening years, the RMC model has been improved, the power of computers has increased significantly, and thermodynamic subroutine libraries have become available. This thesis is the result of extensive work based on these three factors. A prototype computer program (referred to as SC11) has been developed that uses a thermodynamic subroutine library to calculate thermodynamic equilibria using Gibbs energy minimization. The Gibbs energy minimization requires the system temperature (T) and pressure (P), and the inventory of chemical elements (n) in the system. In order to calculate the inventory of chemical elements in the fuel, the list of nuclides and nuclear isomers modelled in SC11 had to be expanded from the list used by SOURCE 2.0. A

  6. Fission product release as a function of chemistry and fuel morphology

    International Nuclear Information System (INIS)

    Hobbins, R.R.; Osetek, D.J.; Petti, D.A.; Hagrman, D.L.

    1989-01-01

    Analysis of the consequences of severe reactor accidents requires knowledge of the location and chemical form of fission products throughout the accident sequence. Two factors that strongly influence the location and chemical form of fission products are the chemistry within the core and the morphology of the fuel or fuel-bearing debris. This paper reviews the current understanding of the these factors garnered from integral and separate effect experiments and the TMI-2 accident, and provides perspective on the significance of contributing phenomena for the analysis of severe accidents, particularly during the in-vessel phase. Information has been obtained recently on phenomena affecting the release of fission products from fuel and the reactor vessel during the in-vessel melt progression phase of a severe accident. The influence of a number of these phenomena will be reviewed, including fuel chemistry, H 2 /H 2 O ratio, fuel liquefaction, molten pools, and debris beds. 13 refs., 1 fig., 1 tab

  7. Silver-Ion-Exchanged Nanostructured Zeolite X as Antibacterial Agent with Superior Ion Release Kinetics and Efficacy against Methicillin-Resistant Staphylococcus aureus.

    Science.gov (United States)

    Chen, Shaojiang; Popovich, John; Iannuzo, Natalie; Haydel, Shelley E; Seo, Dong-Kyun

    2017-11-15

    As antibiotic resistance continues to be a major public health problem, antimicrobial alternatives have become critically important. Nanostructured zeolites have been considered as an ideal host for improving popular antimicrobial silver-ion-exchanged zeolites, because with very short diffusion path lengths they offer advantages in ion diffusion and release over their conventional microsized zeolite counterparts. Herein, comprehensive studies are reported on materials characteristics, silver-ion release kinetics, and antibacterial properties of silver-ion-exchanged nanostructured zeolite X with comparisons to conventional microsized silver-ion-exchanged zeolite (∼2 μm) as a reference. The nanostructured zeolites are submicrometer-sized aggregates (100-700 nm) made up of primary zeolite particles with an average primary particle size of 24 nm. The silver-ion-exchanged nanostructured zeolite released twice the concentration of silver ions at a rate approximately three times faster than the reference. The material exhibited rapid antimicrobial activity against methicillin-resistant Staphylococcus aureus (MRSA) with minimum inhibitory concentration (MIC) values ranging from 4 to 16 μg/mL after 24 h exposure in various growth media and a minimum bactericidal concentration (MBC; >99.9% population reduction) of 1 μg/mL after 2 h in water. While high concentrations of silver-ion-exchanged nanostructured zeolite X were ineffective at reducing MRSA biofilm cell viability, efficacy increased at lower concentrations. In consideration of potential medical applications, cytotoxicity of the silver-ion-exchanged nanostructured zeolite X was also investigated. After 4 days of incubation, significant reduction in eukaryotic cell viability was observed only at concentrations 4-16-fold greater than the 24 h MIC, indicating low cytotoxicity of the material. Our results establish silver-ion-exchanged nanostructured zeolites as an effective antibacterial material against dangerous

  8. Encapsulated oligodendrocyte precursor cell fate is dependent on PDGF-AA release kinetics in a 3D microparticle-hydrogel drug delivery system.

    Science.gov (United States)

    Pinezich, Meghan R; Russell, Lauren N; Murphy, Nicholas P; Lampe, Kyle J

    2018-04-16

    Biomaterial drug delivery systems (DDS) can be used to regulate growth factor release and combat the limited intrinsic regeneration capabilities of central nervous system (CNS) tissue following injury and disease. Of particular interest are systems that aid in oligodendrocyte regeneration, as oligodendrocytes generate myelin which surrounds neuronal axons and helps transmit signals throughout the CNS. Oligodendrocyte precursor cells (OPCs) are found in small numbers in the adult CNS, but are unable to effectively differentiate following CNS injury. Delivery of signaling molecules can initiate a favorable OPC response, such as proliferation or differentiation. Here, we investigate the delivery of one such molecule, platelet derived growth factor-AA (PDGF-AA), from poly(lactic-co-glycolic) acid microparticles to OPCs in a 3D polyethylene glycol-based hydrogel. The goal of this DDS was to better understand the relationship between PDGF-AA release kinetics and OPC fate. The system approximates native brain tissue stiffness, while incorporating PDGF-AA under seven different delivery scenarios. Within this DDS, supply of PDGF-AA followed by PDGF-AA withdrawal caused OPCs to upregulate gene expression of myelin basic protein (MBP) by factors of 1.6-9.2, whereas continuous supply of PDGF-AA caused OPCs to remain proliferative. At the protein expression level, we observed an upregulation in O1, a marker for mature oligodendrocytes. Together, these results show that burst release followed by withdrawal of PDGF-AA from a hydrogel DDS stimulates survival, proliferation, and differentiation of OPCs in vitro. Our results could inform the development of improved neural regeneration strategies that incorporate delivery of PDGF-AA to the injured CNS. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2018. © 2018 Wiley Periodicals, Inc.

  9. Application of controlled release glass in the production of French marigold (Tagetes patula L.

    Directory of Open Access Journals (Sweden)

    Vujošević Ana

    2012-01-01

    Full Text Available This paper investigates the possibility and justification of controlled release glass application as a new ecological material in the production of plants-seedlings of French marigold (Tagetes patula L.. During the investigation its influence on the development of the produced plants-seedlings was monitored. The seedlings were produced in poly-propylene containers (speedling system and poly-propylene pots (pot system. The trial was conducted in the greenhouse at the Faculty of Agriculture in Belgrade during 2011. In the course of seedling production the glass granulation of < 0.5 mm was added in the following doses: 0, 1, 2, 3, and 4 g/l. The results of the research show a positive effect of controlled release glass application in the production of French marigold seedlings, since high quality seedlings were produced justifying its application. The best effect on the analyzed parameters of plant-seedling development was found when substrate was applied in the dose of 1 g/l.

  10. Development and application of the PBMR fission product release calculation model

    International Nuclear Information System (INIS)

    Merwe, J.J. van der; Clifford, I.

    2008-01-01

    At PBMR, long-lived fission product release from spherical fuel spheres is calculated using the German legacy software product GETTER. GETTER is a good tool when performing calculations for fuel spheres under controlled operating conditions, including irradiation tests and post-irradiation heat-up experiments. It has proved itself as a versatile reactor analysis tool, but is rather cumbersome when used for accident and sensitivity analysis. Developments in depressurized loss of forced cooling (DLOFC) accident analysis using GETTER led to the creation of FIssion Product RElease under accident (X) conditions (FIPREX), and later FIPREX-GETTER. FIPREX-GETTER is designed as a wrapper around GETTER so that calculations can be carried out for large numbers of fuel spheres with design and operating parameters that can be stochastically varied. This allows full Monte Carlo sensitivity analyses to be performed for representative cores containing many fuel spheres. The development process and application of FIPREX-GETTER in reactor analysis at PBMR is explained and the requirements for future developments of the code are discussed. Results are presented for a sample PBMR core design under normal operating conditions as well as a suite of design-base accident events, illustrating the functionality of FIPREX-GETTER. Monte Carlo sensitivity analysis principles are explained and presented for each calculation type. The plan and current status of verification and validation (V and V) is described. This is an important and necessary process for all software and calculation model development at PBMR

  11. Comparison of dust release from epoxy and paint nanocomposites and conventional products during sanding and sawing.

    Science.gov (United States)

    Gomez, Virginia; Levin, Marcus; Saber, Anne T; Irusta, Silvia; Dal Maso, Miikka; Hanoi, Roberto; Santamaria, Jesus; Jensen, Keld A; Wallin, Håkan; Koponen, Ismo K

    2014-10-01

    The release of dust generated during sanding or sawing of nanocomposites was compared with conventional products without nanomaterials. Epoxy-based polymers with and without carbon nanotubes, and paints with different amounts of nano-sized titanium dioxide, were machined in a closed aerosol chamber. The temporal evolution of the aerosol concentration and size distribution were measured simultaneously. The morphology of collected dust by scanning electron microscopy was different depending on the type of nanocomposites: particles from carbon nanotubes (CNTs) nanocomposites had protrusions on their surfaces and aggregates and agglomerates are attached to the paint matrix in particles emitted from alkyd paints. We observed no significant differences in the particle size distributions when comparing sanding dust from nanofiller containing products with dust from conventional products. Neither did we observe release of free nanomaterials. Instead, the nanomaterials were enclosed or partly enclosed in the matrix. A source strength term Si (cm(-3) s(-1)) that describes particle emission rates from continuous sources was introduced. Comparison between the Si parameters derived from sanding different materials allows identification of potential effects of addition of engineered nanoparticles to a composite. © The Author 2014. Published by Oxford University Press on behalf of the British Occupational Hygiene Society.

  12. LOFT/LP-FP-1B, Loss of Fluid Test, Fission Product Release Experiment

    International Nuclear Information System (INIS)

    1989-01-01

    1 - Description of test facility: The LOFT Integral Test Facility is a scale model of a LPWR. The intent of the facility is to model the nuclear, thermal-hydraulic phenomena which would take place in a LPWR during a LOCA. The general philosophy in scaling coolant volumes and flow areas in LOFT was to use the ratio of the LOFT core [50 MW(t)] to a typical LPWR core [3000 MW(t)]. For some components, this factor is not applied; however, it is used as extensively as practical. In general, components used in LOFT are similar in design to those of a LPWR. Because of scaling and component design, the LOFT LOCA is expected to closely model a LPWR LOCA. 2 - Description of test: The seventh OECD LOFT experiment was conducted on 19 December 1984. It was the first of the two experiments to be performed in the LOFT facility with intentional release of fission products. Its objectives were to obtain data on fission product release from the fuel-cladding gap into vapor and reflood water and to collect data on transport of these fission products through and out of the reactor coolant system. The experiment was initiated by a reactor scram with one second delayed opening of the quick-opening blowdown valves. 3 - Experimental limitations or shortcomings: Short core and steam generator, excessive core bypass, other scaling compromises, and lack of adequate measurements in certain areas

  13. LOFT/LP-FP-2, Loss of Fluid Test, Fission Product Release from Fuel

    International Nuclear Information System (INIS)

    1989-01-01

    1 - Description of test facility: The LOFT Integral Test Facility is a scale model of a LPWR. The intent of the facility is to model the nuclear, thermal-hydraulic phenomena which would take place in a LPWR during a LOCA. The general philosophy in scaling coolant volumes and flow areas in LOFT was to use the ratio of the LOFT core [50 MW(t)] to a typical LPWR core [3000 MW(t)]. For some components, this factor is not applied; however, it is used as extensively as practical. In general, components used in LOFT are similar in design to those of a LPWR. Because of scaling and component design, the LOFT LOCA is expected to closely model a LPWR LOCA. 2 - Description of test: The eighth OECD LOFT experiment was conducted on 7 March 1985. It was the second of the two experiments to be performed in the LOFT facility with intentional release of fission products. Its principal objectives were to determine the fission product release from the fuel during a severe fuel damage scenario and the subsequent transport of these fission products in a predominantly vapor/aerosol environment. This was the largest severe fuel damage experiment ever conducted, and serves as an important benchmark between smaller scale tests and the TMI-2 accident. 3 - Experimental limitations or shortcomings: Short core and steam generator, excessive core bypass, other scaling compromises, and lack of adequate measurements in certain areas

  14. Fission product releases at severe LWR accident conditions: ORNL/CEA measurements versus calculations

    Energy Technology Data Exchange (ETDEWEB)

    Andre, B.; Ducros, G.; Leveque, J.P. [CEA Centre d`Etudes de Grenoble, 38 (France). Dept. de Thermohydraulique et de Physique; Osborne, M.F.; Lorenz, R.A. [Oak Ridge National Lab., TN (United States); Maro, D. [CEA Centre d`Etudes de Fontenay-aux-Roses, 92 (France). Dept. de Protection de l`Environnement et des Installations

    1995-12-31

    Experimental programs in the United States and France have followed similar paths in supplying much of the data needed to analyze severe accidents. Both the HI/VI program, conducted at the Oak Ridge National Laboratory (ORNL) under the sponsorship of the U. S. Nuclear Regulatory Commission (NRC), and the HEVA/VERCORS program, supported by IPSN-Commissariat a l`Energie Atomique (CEA) and carried out at the Centre d`Etudes Nucleaires de Grenoble, have studied fission product release from light water reactor (LWR) fuel samples during test sequences representative of severe accidents. Recognizing that more accurate data, i.e., a better defined source term, could reduce the safety margins included in the rather conservative source terms originating from WASH-1400, the primary objective of these programs has been to improve the data base concerning fission product release and behavior at high temperatures. To facilitate the comparison, a model based on fission product diffusion mechanisms that was developed at ORNL and adapted with CEA experimental data is proposed. This CEA model is compared with the ORNL experimental data in a blind test. The two experimental programs used similar techniques in out-of-pile studies. Highly irradiated fuel samples were heated in radiofrequency induction furnaces to very high temperatures (up to 2700 K at ORNL and 2750 K at CEA) in oxidizing (H{sub 2}O), reducing (H{sub 2}) or mixed (H{sub 2}O+H{sub 2}) environments. The experimental parameters, which were chosen from calculated accident scenarios, did not duplicate specific accidents, but rather emphasized careful control of test conditions to facilitate extrapolation of the results to a wide variety of accident situations. This paper presents a broad and consistent database from ORNL and CEA release results obtained independently since the early 1980`S. A comparison of CORSOR and CORSOR Booth calculations, currently used in safety analysis, and the experimental results is presented and

  15. Quantitative production of compound I from a cytochrome P450 enzyme at low temperatures. Kinetics, activation parameters, and kinetic isotope effects for oxidation of benzyl alcohol.

    Science.gov (United States)

    Wang, Qin; Sheng, Xin; Horner, John H; Newcomb, Martin

    2009-08-05

    Cytochrome P450 enzymes are commonly thought to oxidize substrates via an iron(IV)-oxo porphyrin radical cation transient termed Compound I, but kinetic studies of P450 Compounds I are essentially nonexistent. We report production of Compound I from cytochrome P450 119 (CYP119) in high conversion from the corresponding Compound II species at low temperatures in buffer mixtures containing 50% glycerol by photolysis with 365 nm light from a pulsed lamp. Compound I was studied as a reagent in oxidations of benzyl alcohol and its benzylic mono- and dideuterio isotopomers. Pseudo-first-order rate constants obtained at -50 degrees C with concentrations of substrates between 1.0 and 6.0 mM displayed saturation kinetics that gave binding constants for the substrate in the Compound I species (K(bind)) and first-order rate constants for the oxidation reactions (k(ox)). Representative results are K(bind) = 214 M(-1) and k(ox) = 0.48 s(-1) for oxidation of benzyl alcohol. For the dideuterated substrate C(6)H(5)CD(2)OH, kinetics were studied between -50 and -25 degrees C, and a van't Hoff plot for complexation and an Arrhenius plot for the oxidation reaction were constructed. The H/D kinetic isotope effects (KIEs) at -50 degrees C were resolved into a large primary KIE (P = 11.9) and a small, inverse secondary KIE (S = 0.96). Comparison of values extrapolated to 22 degrees C of both the rate constant for oxidation of C(6)H(5)CD(2)OH and the KIE for the nondeuterated and dideuterated substrates to values obtained previously in laser flash photolysis experiments suggested that tunneling could be a significant component of the total rate constant at -50 degrees C.

  16. Online ICPMS detection of the thermal release of fission products from nuclear fuel samples

    International Nuclear Information System (INIS)

    Guenther-Leopold, I.; Svedkauskaite-Le Gore, J.; Kivel, N.

    2009-01-01

    Full text: The release of volatile and semi-volatile fission products (like Cs, Tc, Mo etc.) from spent nuclear fuel by thermal and thermochemical treatment (oxidative or reductive conditions) as a head-end step for advanced reprocessing scenarios is studied in the Hot Laboratory of the Paul Scherrer Institut. For this purpose, a heated sampling cell online connected to an ICPMS (Element 2, Thermo Fisher Scientific) was designed and tested on simulated fuel samples up to 650 o C. The results of this study as well as technical perspectives for heating experiments up to 2000 o C will be presented. (author)

  17. Interleukin-2 stimulates osteoclastic activity: Increased acid production and radioactive calcium release

    International Nuclear Information System (INIS)

    Ries, W.L.; Seeds, M.C.; Key, L.L.

    1989-01-01

    Recombinant human interleukin-2 (IL-2) was studied to determine effects on acid production by individual osteoclasts in situ on mouse calvarial bones. This analysis was performed using a microspectrofluorimetric technique to quantify acid production in individual cells. Radioactive calcium release was determined using calvarial bones in a standard tissue culture system. This allowed us to correlate changes in acid production with a measure of bone resorption. IL-2 stimulated acid production and bone resorbing activity. Both effects were inhibited by calcitonin. No stimulation of bone resorption occurred when IL-2-containing test media was incubated with a specific anti-IL-2 antibody and ultrafiltered. Our data demonstrated a correlation between acid production and bone resorbing activity in mouse calvaria exposed to parathyroid hormone (PTH). The data obtained from cultured mouse calvaria exposed to IL-2 demonstrated similar stimulatory effects to those seen during PTH exposure. These data suggest that calvaria exposed to IL-2 in vitro have increased osteoclastic acid production corresponding with increased bone resorption. (author)

  18. Development of dose assessment code for accidental releases of activation products

    International Nuclear Information System (INIS)

    Noguchi, H.; Yokoyama, S.

    2000-01-01

    It is expected that activation products will be important radionuclides as well as tritium in the assessment of the public doses necessary for licensing of a future fusion reactor. In order to calculate the public doses due to the activation products released in cases of accidents, a code named ACUTAP (dose assessment code for ACUTe Activation Product releases) has been developed. Major characteristics of the code are as follows: (1) the transfer model reflects specific behavior of the activation products in the environment, (2) the doses are assessed based on ICRP dose models, (3) it is possible to calculate individual doses using annual meteorological data statistically according to the guide of the Nuclear Safety Commission of Japan, and (4) the code can calculate collective doses as well as individual doses. Individual doses are calculated for the following pathways: internal exposure by inhalation of activation products in a plume and those resuspended from the ground, external exposure from a plume (cloudshine), and external exposure from activation products deposited on the ground (groundshine). The inhalation in a plume and cloudshine pathways are included in the model for calculating collective doses. In addition to parent nuclides released from the facilities, progeny nuclides produced during the atmospheric dispersion are considered in calculating inhalation doses, and those during the deposition period in calculating groundshine doses. External doses from the cloudshine are calculated for 18 energy groups instead of individual energy of emitted gamma rays in order to save the computation time. Atmospheric concentrations are calculated using a Gaussian plume model with atmospheric dispersion parameters prescribed in the guide of the Nuclear Safety Commission of Japan. Data sets of parameters necessary for the dose assessment, such as internal dos coefficients, external dose rate conversion factors and half lives, are prepared for about 100 radionuclides

  19. Thermodynamic analysis for syngas production from volatiles released in waste tire pyrolysis

    International Nuclear Information System (INIS)

    Martínez, Juan Daniel; Murillo, Ramón; García, Tomás; Arauzo, Inmaculada

    2014-01-01

    Highlights: • Pyrolysis experiments have been conducted in a continuous auger reactor. • Pyrolysis temperature influence on composition of both volatiles and char was studied. • A process for syngas production has been proposed from the volatiles. • Equivalence ratio down to 0.4 is a practical limit for syngas production. • The results provide essential data prior to perform any experimental campaign. - Abstract: This paper shows the maximum limit on syngas composition obtained from volatiles released in waste tire pyrolysis when they are submitted to an air–steam partial oxidation process. Thus, from mass and energy balances and a stoichiometric equilibrium model, syngas composition and reaction temperature as well as some process parameters were predicted by varying both the equivalence ratio (ER) and the steam to fuel ratio (SF). In addition, pyrolysis experiments were performed using a continuous auger reactor, and the influence of pyrolysis temperature on composition of both volatiles and char was studied. Consequently, the resulting syngas characteristics were correlated with the pyrolysis temperature. The stoichiometric equilibrium model showed that an ER down to 0.4 is a practical limit to perform the air–steam partial oxidation process. When the process is carried out only with air, volatiles obtained at high pyrolysis temperature lead to lower reaction temperature and higher LHV of syngas in comparison with those found at low pyrolysis temperature. The H 2 production is favored between 0.20 and 0.40 of ER and seems to be more influenced by the H/C ratio than by the water gas-shift reaction. On the other hand, the steam addition shows a more notable effect on the H 2 production for volatiles obtained at the highest pyrolysis temperature (600 °C) in agreement with the lower reaction temperature under these experimental conditions. This thermodynamic analysis provides essential data on the optimization of syngas production from volatiles

  20. Photodegradation of malachite green under simulated and natural irradiation: Kinetics, products, and pathways

    International Nuclear Information System (INIS)

    Yong, Li; Zhanqi, Gao; Yuefei, Ji; Xiaobin, Hu; Cheng, Sun; Shaogui, Yang; Lianhong, Wang; Qingeng, Wang; Die, Fang

    2015-01-01

    Highlights: • Photofate of malachite green was studied under simulated and natural irradiation. • Favorable conditions for degradation were optimized by the orthogonal array design. • Main ROS for the decomposition were determined by free radical quenchers. • Fifty-three products were determined by LC–MS and GC–MS. • Pathways were proposed with the aid of theoretical calculation. - Abstract: In this work photodegradation rates and pathways of malachite green were studied under simulated and solar irradiation with the goal of assessing the potential of photolysis as a removal mechanism in real aquatic environment. Factors influencing the photodegradation process were investigated, including pH, humic acid, Fe 2+ , Ca 2+ , HCO 3 − , and NO 3 − , of which favorable conditions were optimized by the orthogonal array design under simulated sunlight irradiation in the presence of dissolved oxygen. The degradation processes of malachite green conformed to pseudo first-order kinetics and their degradation rate constants were between 0.0062 and 0.4012 h −1 . Under solar irradiation, the decolorization efficiency of most tests can reach almost 100%, and relatively thorough mineralization could be observed. Forty degradation products were detected by liquid chromatography–mass spectrometry, and thirteen small molecular products were identified by gas chromatography–mass spectrometry. Based on the analyses of the degradation products and calculation of the frontier electron density, the pathways were proposed: decomposition of conjugated structure, N-demethylation reactions, hydroxyl addition reactions, the removal of benzene ring, and the ring-opening reaction. This study has provided a reference, both for photodegradation of malachite green and future safety applications and predictions of decontamination of related triphenylmethane dyes under real conditions

  1. Photodegradation of malachite green under simulated and natural irradiation: Kinetics, products, and pathways

    Energy Technology Data Exchange (ETDEWEB)

    Yong, Li [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210023 (China); Zhanqi, Gao [State Environmental Protection Key Laboratory of Monitoring and Analysis for Organic Pollutants in Surface Water, Jiangsu Provincial Environmental Monitoring Center, Nanjing 210036 (China); Yuefei, Ji [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210023 (China); Xiaobin, Hu [School of Life Science, Huzhou University, Huzhou 313000 (China); Cheng, Sun, E-mail: envidean@nju.edu.cn [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210023 (China); Shaogui, Yang; Lianhong, Wang; Qingeng, Wang; Die, Fang [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210023 (China)

    2015-03-21

    Highlights: • Photofate of malachite green was studied under simulated and natural irradiation. • Favorable conditions for degradation were optimized by the orthogonal array design. • Main ROS for the decomposition were determined by free radical quenchers. • Fifty-three products were determined by LC–MS and GC–MS. • Pathways were proposed with the aid of theoretical calculation. - Abstract: In this work photodegradation rates and pathways of malachite green were studied under simulated and solar irradiation with the goal of assessing the potential of photolysis as a removal mechanism in real aquatic environment. Factors influencing the photodegradation process were investigated, including pH, humic acid, Fe{sup 2+}, Ca{sup 2+}, HCO{sub 3}{sup −}, and NO{sub 3}{sup −}, of which favorable conditions were optimized by the orthogonal array design under simulated sunlight irradiation in the presence of dissolved oxygen. The degradation processes of malachite green conformed to pseudo first-order kinetics and their degradation rate constants were between 0.0062 and 0.4012 h{sup −1}. Under solar irradiation, the decolorization efficiency of most tests can reach almost 100%, and relatively thorough mineralization could be observed. Forty degradation products were detected by liquid chromatography–mass spectrometry, and thirteen small molecular products were identified by gas chromatography–mass spectrometry. Based on the analyses of the degradation products and calculation of the frontier electron density, the pathways were proposed: decomposition of conjugated structure, N-demethylation reactions, hydroxyl addition reactions, the removal of benzene ring, and the ring-opening reaction. This study has provided a reference, both for photodegradation of malachite green and future safety applications and predictions of decontamination of related triphenylmethane dyes under real conditions.

  2. Reactions of the CN Radical with Benzene and Toluene: Product Detection and Low-Temperature Kinetics

    Energy Technology Data Exchange (ETDEWEB)

    Trevitt, Adam J.; Goulay, Fabien; Taatjes, Craig A.; Osborn, David L.; Leone, Stephen R.

    2009-12-23

    Low temperature rate coefficients are measured for the CN + benzene and CN + toluene reactions using the pulsed Laval nozzle expansion technique coupled with laser-induced fluorescence detection. The CN + benzene reaction rate coefficient at 105, 165 and 295 K is found to be relatively constant over this temperature range, 3.9 - 4.9 x 10-10 cm3 molecule-1 s-1. These rapid kinetics, along with the observed negligible temperature dependence, are consistent with a barrierless reaction entrance channel and reaction efficiencies approaching unity. The CN + toluene reaction is measured to have a slower rate coefficient of 1.3 x 10-10 cm3 molecule-1 s-1 at 105 K. At room temperature, non-exponential decay profiles are observed for this reaction that may suggest significant back-dissociation of intermediate complexes. In separate experiments, the products of these reactions are probed at room temperature using synchrotron VUV photoionization mass spectrometry. For CN + benzene, cyanobenzene (C6H5CN) is the only product recorded with no detectable evidence for a C6H5 + HCN product channel. In the case of CN + toluene, cyanotoluene (NCC6H4CH3) constitutes the only detected product. It is not possible to differentiate among the ortho, meta and para isomers of cyanotoluene because of their similar ionization energies and the ~;; 40 meV photon energy resolution of the experiment. There is no significant detection of benzyl radicals (C6H5CH2) that would suggest a H-abstraction or a HCN elimination channel is prominent at these conditions. As both reactions are measured to be rapid at 105 K, appearing to have barrierless entrance channels, it follows that they will proceed efficiently at the temperatures of Saturn?s moon Titan (~;;100 K) and are also likely to proceed at the temperature of interstellar clouds (10-20 K).

  3. Simultaneous saccharification and bioethanol production from corn cobs: Process optimization and kinetic studies.

    Science.gov (United States)

    Sewsynker-Sukai, Yeshona; Gueguim Kana, E B

    2018-08-01

    This study investigates the simultaneous saccharification and fermentation (SSF) process for bioethanol production from corn cobs with prehydrolysis (PSSF) and without prehydrolysis (OSSF). Two response surface models were developed with high coefficients of determination (>0.90). Process optimization gave high bioethanol concentrations and bioethanol conversions for the PSSF (36.92 ± 1.34 g/L and 62.36 ± 2.27%) and OSSF (35.04 ± 0.170 g/L and 58.13 ± 0.283%) models respectively. Additionally, the logistic and modified Gompertz models were used to study the kinetics of microbial cell growth and ethanol formation under microaerophilic and anaerobic conditions. Cell growth in the OSSF microaerophilic process gave the highest maximum specific growth rate (µ max ) of 0.274 h -1 . The PSSF microaerophilic bioprocess gave the highest potential maximum bioethanol concentration (P m ) (42.24 g/L). This study demonstrated that microaerophilic rather than anaerobic culture conditions enhanced cell growth and bioethanol production, and that additional prehydrolysis steps do not significantly impact on the bioethanol concentration and conversion in SSF process. Copyright © 2018 Elsevier Ltd. All rights reserved.

  4. Study on fermentation kinetics and extraction process of rhamnolipid production by papermaking wastewater

    Science.gov (United States)

    Yu, Keer

    2018-01-01

    Paper mill wastewater (PMW) is the outlet water generated during pulp and papermaking process in the paper industry. Fermentation by wastewater can lower the cost of production as well as alleviate the pressure of wastewater treatment. Rhamnolipids find broad placations as natural surfactants. This paper studied the rhamnolipids fermentation by employing Pseudomonas aeruginosa isolated by the laboratory, and determined to use wastewater which filtered by medium speed filter paper and strain Z2, the culture conditions were optimized, based on the flask shaking fermentation. On the basis of 5L tank fermentation, batch fermentation was carried out, the yield of fermentation reached 7.067g/L and the fermentation kinetics model of cell growth, product formation and substrate consumption was established by using origin software, and the fermentation process could be simulated well. And studied on the extraction process of rhamnolipids, through fermentation dynamic equation analysis can predict the in fill material yield can be further improved. Research on the extraction process of rhamnolipid simplifies the operation of extraction, and lays the foundation for the industrial extraction.

  5. Effects of heating rate on slow pyrolysis behavior, kinetic parameters and products properties of moso bamboo.

    Science.gov (United States)

    Chen, Dengyu; Zhou, Jianbin; Zhang, Qisheng

    2014-10-01

    Effects of heating rate on slow pyrolysis behaviors, kinetic parameters, and products properties of moso bamboo were investigated in this study. Pyrolysis experiments were performed up to 700 °C at heating rates of 5, 10, 20, and 30 °C/min using thermogravimetric analysis (TGA) and a lab-scale fixed bed pyrolysis reactor. The results show that the onset and offset temperatures of the main devolatilization stage of thermogravimetry/derivative thermogravimetry (TG/DTG) curves obviously shift toward the high-temperature range, and the activation energy values increase with increasing heating rate. The heating rate has different effects on the pyrolysis products properties, including biochar (element content, proximate analysis, specific surface area, heating value), bio-oil (water content, chemical composition), and non-condensable gas. The solid yields from the fixed bed pyrolysis reactor are noticeably different from those of TGA mainly because the thermal hysteresis of the sample in the fixed bed pyrolysis reactor is more thorough. Copyright © 2014 Elsevier Ltd. All rights reserved.

  6. A Status of Art-Report on the Fission Products Behavior Released from Spent Fuel at High Temperature Conditions

    International Nuclear Information System (INIS)

    Park, Geun Il; Kim, J. H.; Lee, J. W.

    2003-04-01

    The experiments on the fission products release behavior from spent fuel at high temperature assuming reactor accident conditions have been carried out at Oak Ridge Nation Laboratory of USA in HI/VI tests, CEA of France in HEVA/VERCOS tests, AEA of England and CRNL of Canada in HOX test. The VEGA program to study the fission product release behavior from LWR irradiated fuel was recently initiated at JAERI. The key parameter affecting the fission product(FP) release behavior is temperature. In addition, other parameters such as fuel oxidation, burnup, pre-transient conditions are found to affect the FP releases considerably in the earlier tests. The atmosphere conditions such as oxidizing atmosphere (steam or air) or reducing atmosphere (hydrogen) can cause significant change of FPs release and transport behavior due to chemical forms of the reactive FPs which is dependent on the oxidation potential. The effect of fuel burnup on the Kr-85 or Cs-137 release showed that the release rates of these radionuclides increased with the increase of burnup, meaning that release rates are dominated by the atomic diffusions in the grains and they are primarily a function of temperature. However, the data on FPs release behavior using higher burnups above 50,000 MWD/MTU are not so many reported up to now. This report summarizes the test results of FPs release behavior in reactor accident conditions produced from other countries mentioned above. This review and analysis on earlier studies would be useful for predicting the release characteristics of FPs from domestic spent fuel. The release rates of fission gas or FPs from spent fuel at high temperature conditions during fabrication process of dry recycling fuel were also analyzed using many data obtained from earlier tests

  7. 15N kinetic analysis of N2O production by Nitrosomonas europaea: an examination of nitrifier denitrification

    International Nuclear Information System (INIS)

    Poth, M.; Focht, D.D.

    1985-01-01

    A series of 15 N isotope tracer experiments showed that Nitrosomonas europaea produces nitrous oxide only under oxygen-limiting conditions and that the labeled N from nitrite, but not nitrate, is incorporated into nitrous oxide, indicating the presence of the denitrifying enzyme nitrite reductase. A kinetic analysis of the m/z 44, 45, and 46 nitrous oxide produced by washed cell suspensions of N. europaea when incubated with 4 mM ammonium (99% 14 N) and 0.4 mM nitrite (99% 15 N) was performed. No labeled nitirte was reduced to ammonium. All labeled material added was accounted for as either nitrite or nitrous oxide. The hypothesis that nitrous oxide is produced directly from nitrification was rejected since (i) it does not allow for the large amounts of double-labeled (m/z 46) nitrous oxide observed; (ii) the observed patterns of m/z 44, 45, 46 nitrous oxide were completely consistent with a kinetic analysis based on denitrification as the sole mechanism of nitrous oxide production but not with a kinetic analysis based on both mechanisms; (iii) the asymptotic ratio of m/z 45 to m/z 46 nitrous oxide was consistent with denitrification kinetics but inconsistent with nitrification kinetics, which predicted no limit to m/z 45 production. It is concluded that N. europaea is a denitrifier which, under conditions of oxygen stress, uses nitrite as a terminal electron acceptor and produces nitrous oxide

  8. KINETICS OF GROWTH AND ETHANOL PRODUCTION ON DIFFERENT CARBON SUBSTRATES USING GENETICALLY ENGINEERED XYLOSE-FERMENTING YEAST

    Science.gov (United States)

    Saccharomyces cerevisiae 424A (LNH-ST) strain was used for fermentation of glucose and xylose. Growth kinetics and ethanol productivity were calculated for batch fermentation on media containing different combinations of glucose and xylose to give a final sugar concentra...

  9. Thermophysical modeling of volatile fission product release from a debris pool

    International Nuclear Information System (INIS)

    Yun, J. I.; Suh, K. Y.; Kang, C. S.

    1999-01-01

    A model is described for fission product release from the debris pool in the lower plenum of the reactor pressure vessel. In the pool, turbulent natural convection flow is formed due to homogeneous internal heat generation. Using the best-known correlations, heat transfer at the curved bottom and the top of the pool may be calculated. Volatile fission product gases in the pool nucleate and diffuse to bubbles. Both the homogeneous nucleation and heterogeneous nucleation are considered. The bubble nucleation, growth, coalescence and loss due to rise is modeled pursuant to bubble dynamics. If the pressure and temperature of the pool are very high, homogeneous nucleation that accounts for effect of decrease in the pool pressure can occur. The effect of the bubble-to-pool interfacial tension and the pool pressure on the nucleation rate is investigated in this work

  10. Modifying release characteristics from 3D printed drug-eluting products

    DEFF Research Database (Denmark)

    Boetker, Johan; Water, Jorrit; Aho, Johanna

    2016-01-01

    Abstract This work describes an approach to modify the release of active compound from a 3D printed model drug product geometry intended for flexible dosing and precision medication. The production of novel polylactic acid and hydroxypropyl methylcellulose based feed materials containing...... nitrofurantoin for 3D printing purposes is demonstrated. Nitrofurantoin, Metolose® and polylactic acid were successfully co-extruded with up to 40% Metolose® content, and subsequently 3D printed into model disk geometries (ø10 mm, h = 2 mm). Thermal analysis with differential scanning calorimetry and solid phase...... identification with Raman spectroscopy showed that nitrofurantoin remained in its original solid form during both hot-melt extrusion and subsequent 3D printing. Rheological measurements of the different compositions showed that the flow properties were sensitive to the amount of undissolved particles present...

  11. Effect of a controlled-release albendazole capsule on parasitism and productivity of sheep.

    Science.gov (United States)

    Corba, J; Krupicer, I; Legény, J; Juris, P; Veselý, L

    1991-11-01

    The efficacy of intraruminal albendazole (ABZ) capsules (Profitril-Captec) and the effect of treatment on productivity were studied in 300 ewes infected with gastrointestinal nematodes and the trematode Dicrocoelium dendriticum. Coprological tests revealed that treated animals remained negative for 10 weeks after the administration of capsules. Contamination of pasture with nematode larvae was significantly reduced during the whole experiment. Necropsy of 14 animals (seven treated and seven untreated) showed 96.9-99.2% efficacy against the nematodes Nematodirus spp., Oesophagostomum spp., Cooperia spp., Trichostrongylus spp. and Trichuris ovis, while efficacy was 88.5% against D. dendriticum. During the 6 month pasture season (May-October 1989), treated ewes produced on average 2.56 kg cheese and 0.6 kg wool per ewe more than untreated controls. Our study confirms the reliability of the ABZ slow-release capsules over 90 days and the positive effect of treatment on nematode contamination of pasture and ewe productivity.

  12. Microfluidic Production of Alginate Hydrogel Particles for Antibody Encapsulation and Release.

    Science.gov (United States)

    Mazutis, Linas; Vasiliauskas, Remigijus; Weitz, David A

    2015-12-01

    Owing to their biocompatibility and reduced side effects, natural polymers represent an attractive choice for producing drug delivery systems. Despite few successful examples, however, the production of monodisperse biopolymer-based particles is often hindered by high viscosity of polymer fluids. In this work, we present a microfluidic approach for production of alginate-based particles carrying encapsulated antibodies. We use a triple-flow micro-device to induce hydrogel formation inside droplets before their collection off-chip. The fast mixing and gelation process produced alginate particles with a unique biconcave shape and dimensions of the mammalian cells. We show slow and fast dissolution of particles in different buffers and evaluate antibody release over time. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. The effect of UO2 density on fission product gas release and sheath expansion

    International Nuclear Information System (INIS)

    Notley, M.J.F.; MacEwan, J.R.

    1965-03-01

    The effect of UO 2 density on fission product gas release and sheath expansion has been determined in an irradiation experiment in which the performance of fuel elements with densities between 10.42 and 10.74 g/cm 3 was compared at ∫λdθ values of 39 and 42 W/cm. The elements were irradiated as clusters of four in a pressurized water loop, hence their irradiation histories were identical. Fission product gas release and the extend of grain growth were greater for the lower density elements. Both effects can be attributed solely to the variation of the thermal conductivity of the fuel with the fractional porosity p, if λ p λ [1 - (2.6 ± 0.8) p] where λ is the thermal conductivity of fully dense UO 2 and λ p is that of the porous UO 2 . This expression is in agreement with laboratory findings. A correlation between the extent of grain growth in the UO 2 and the fractional gas release was found to exist in this test and was shown to apply in a large number of other fuel irradiations. Diametral sheath strain was lower for the low density fuel elements than for those of high density, although the former were deduced to have operated with higher central temperatures. It is supposed that the thermal expansion of the fuel can be partially accommodated by elimination of some of the original porosity. The data are consistent with the assumption that approximately half the porosity in the region of the fuel undergoing grain growth is eliminated. (author)

  14. Gonadotropin-Releasing Hormone Stimulate Aldosterone Production in a Subset of Aldosterone-Producing Adenoma

    Science.gov (United States)

    Kishimoto, Rui; Oki, Kenji; Yoneda, Masayasu; Gomez-Sanchez, Celso E.; Ohno, Haruya; Kobuke, Kazuhiro; Itcho, Kiyotaka; Kohno, Nobuoki

    2016-01-01

    Abstract We aimed to detect novel genes associated with G protein-coupled receptors (GPCRs) in aldosterone-producing adenoma (APA) and elucidate the mechanisms underlying aldosterone production. Microarray analysis targeting GPCR-associated genes was conducted using APA without known mutations (APA-WT) samples (n = 3) and APA with the KCNJ5 mutation (APA-KCNJ5; n = 3). Since gonadotropin-releasing hormone receptor (GNRHR) was the highest expression in APA-WT by microarray analysis, we investigated the effect of gonadotropin-releasing hormone (GnRH) stimulation on aldosterone production. The quantitative polymerase chain reaction assay results revealed higher GNRHR expression levels in APA-WT samples those in APA-KCNJ5 samples (P APA-WT samples, and there was a significant and positive correlation between GNRHR and LHCGR expression in all APA samples (r = 0.476, P APA-WT (n = 9), which showed higher GNRHR and LHCGR levels, had significantly higher GnRH-stimulated aldosterone response than those with APA-KCNJ5 (n = 13) (P APA-WT, and the molecular analysis including the receptor expression associated with clinical findings of GnRH stimulation. PMID:27196470

  15. Action of luteinizing hormone-releasing hormone in rat ovarian cells: Hormone production and signal transduction

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jian.

    1989-01-01

    The present study was conducted to investigate the hypothesis that the breakdown of membrane phosphoinositides may participate in the actions of luteinizing hormone-releasing hormone (LHRH) on hormone production in rat granulosa cells. In cells prelabeled with ({sup 3}H)inositol or ({sup 3}H)arachidonic acid (AA), treatment with LHRH increased the formation of radiolabeled inositol 1,4,5-trisphosphate (IP{sub 3}) and diacylglycerol (DG), and the release of radiolabeled AA. Since IP{sub 3} induces intracellular Ca{sup 2+} mobilization, changes in the cytosolic free calcium ion concentrations ((Ca{sup 2+})i) induced by LHRH were studied in individual cells using fura-2 microspectrofluorimetry. Alterations in (Ca{sup 2+})i induced by LHRH were rapid and transient, and could be completely blocked by a LHRH antagonist. Sustained perifusion of LHRH resulted in a desensitization of the (Ca{sup 2+})i response to LHRH. LHRH treatment accelerated (Ca{sup 2+})i depletion in the cells perifused with Ca{sup 2+} free medium, indicating the involvement of intracellular Ca{sup 2+} pool(s) in (Ca{sup 2+})i changes. The actions of LHRH on the regulation of progesterone (P{sub 4}) and prostaglandin E{sub 2} (PGE{sub 2}) production were also examined. LHRH increased basal P{sub 4} production and attenuated FSH induced P{sub 4} production. Both basal and FSH stimulated PGE{sub 2} formation were increased by LHRH. Since LHRH also increased the formation of DG that stimulates the activity of protein kinase C, an activator of protein kinase C (12-0-tetradecanolyphorbol-13-acetate: TPA) was used with the Ca{sup 2+} ionophore A23187 and melittin (an activator of phospholipase A{sub 2}) to examine the roles of protein kinase C, Ca{sup 2+} and free AA, respectively, in LHRH action.

  16. Degradation kinetics of organic chloramines and formation of disinfection by-products during chlorination of creatinine.

    Science.gov (United States)

    Zhang, Tianyang; Xu, Bin; Wang, Anqi; Cui, Changzheng

    2018-03-01

    Organic chloramines can interfere with the measurement of effective combined chlorine in chlorinated water and are potential intermediate products of highly toxic disinfection by-products (DBPs). In order to know more about the degradation and transformation of organic chloramines, a typical organic chloramine precursor creatinine was selected for investigation and a corresponding individual organic chloramine chlorocreatinine was prepared in this study. The preparation condition of chlorocreatinine by chlorination was established as chlorine/creatinine = 1 M/M, reaction time = 2 h and pH = 7.0. Then the degradation kinetics of chlorocreatinine during further chlorination was studied, and a second-order rate constant of 1.16 (±0.14) M -1 s -1 was obtained at pH 7.0. Solution pH significantly influenced the degradation rate, and the elementary rate constants of chlorocreatinine with HOCl+H + , HOCl, OCl - and chlorocreatinine - with OCl - were calculated as 2.43 (±1.55) × 10 4  M -2  s -1 , 1.05 (±0.09) M -1 s -1 , 2.86 (±0.30) M -1 s -1 and 3.09 (±0.24) M -1 s -1 , respectively. Besides, it was found that chlorocreatinine could be further converted into several C-DBPs (chloroform and trichloroacetone) and N-DBPs (dichloroacetonitrile (DCAN) and trichloronitromethane (TCNM)) during chlorination. The total yield of DBPs increased obviously with increasing pH, especially for TCNM. In addition, the presence of humic acid in creatinine solution could increase the formation of DCAN obviously during chlorination. Based on the UPLC-Q-TOF-MS analysis, the conversion pathways of chlorocreatinine were proposed. Several kinds of intermediate products were also identified as organic chloramines and some of them could even exist stably during the further chlorination. Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. Sustainable biobutanol production from pineapple waste by using Clostridium acetobutylicum B 527: Drying kinetics study.

    Science.gov (United States)

    Khedkar, Manisha A; Nimbalkar, Pranhita R; Gaikwad, Shashank G; Chavan, Prakash V; Bankar, Sandip B

    2017-02-01

    Present investigation explores the use of pineapple peel, a food industry waste, for acetone-butanol-ethanol (ABE) production using Clostridium acetobutylicum B 527. Proximate analysis of pineapple peel shows that it contains 35% cellulose, 19% hemicellulose, and 16% lignin on dry basis. Drying experiments on pineapple peel waste were carried out in the temperature range of 60-120°C and experimental drying data was modeled using moisture diffusion control model to study its effect on ABE production. The production of ABE was further accomplished via acid hydrolysis, detoxification, and fermentation process. Maximum total sugar release obtained by using acid hydrolysis was 97g/L with 95-97% and 10-50% removal of phenolics and acetic acid, respectively during detoxification process. The maximum ABE titer obtained was 5.23g/L with 55.6% substrate consumption when samples dried at 120°C were used as a substrate (after detoxification). Copyright © 2016 Elsevier Ltd. All rights reserved.

  18. Products and kinetics of the heterogeneous reaction of suspended vinclozolin particles with ozone.

    Science.gov (United States)

    Gan, Jie; Yang, Bo; Zhang, Yang; Shu, Xi; Liu, Changgeng; Shu, Jinian

    2010-11-25

    Vinclozolin is a widely used fungicide that can be released into the atmosphere via application and volatilization. This paper reports an experimental investigation on the heterogeneous ozonation of vinclozolin particles. The ozonation of vinclozolin adsorbed on azelaic acid particles under pseudo-first-order conditions is investigated online with a vacuum ultraviolet photoionization aerosol time-of-flight mass spectrometer (VUV-ATOFMS). The ozonation products are analyzed with a combination of VUV-ATOFMS and GC/MS. Two main ozonation products are observed. The formation of the ozonation products results from addition of O(3) on the C-C double bond of the vinyl group. The heterogeneous reactive rate constant of vinclozolin particles under room temperature is (2.4 ± 0.4) × 10(-17) cm(3) molecules(-1) s(-1), with a corresponding lifetime at 100 ppbv O(3) of 4.3 ± 0.7 h, which is almost comparable with the estimated lifetime due to the reaction with atmospheric OH radicals (∼1.7 h). The reactive uptake coefficient for O(3) on vinclozolin particles is (6.1 ± 1.0) × 10(-4).

  19. Mechanisms of proton relay and product release by Class A β-lactamase at ultrahigh resolution.

    Science.gov (United States)

    Lewandowski, Eric M; Lethbridge, Kathryn G; Sanishvili, Ruslan; Skiba, Joanna; Kowalski, Konrad; Chen, Yu

    2018-01-01

    The β-lactam antibiotics inhibit penicillin-binding proteins (PBPs) by forming a stable, covalent, acyl-enzyme complex. During the evolution from PBPs to Class A β-lactamases, the β-lactamases acquired Glu166 to activate a catalytic water and cleave the acyl-enzyme bond. Here we present three product complex crystal structures of CTX-M-14 Class A β-lactamase with a ruthenocene-conjugated penicillin-a 0.85 Å resolution structure of E166A mutant complexed with the penilloate product, a 1.30 Å resolution complex structure of the same mutant with the penicilloate product, and a 1.18 Å resolution complex structure of S70G mutant with a penicilloate product epimer-shedding light on the catalytic mechanisms and product inhibition of PBPs and Class A β-lactamases. The E166A-penilloate complex captured the hydrogen bonding network following the protonation of the leaving group and, for the first time, unambiguously show that the ring nitrogen donates a proton to Ser130, which in turn donates a proton to Lys73. These observations indicate that in the absence of Glu166, the equivalent lysine would be neutral in PBPs and therefore capable of serving as the general base to activate the catalytic serine. Together with previous results, this structure suggests a common proton relay network shared by Class A β-lactamases and PBPs, from the catalytic serine to the lysine, and ultimately to the ring nitrogen. Additionally, the E166A-penicilloate complex reveals previously unseen conformational changes of key catalytic residues during the release of the product, and is the first structure to capture the hydrolyzed product in the presence of an unmutated catalytic serine. Structural data are available in the PDB database under the accession numbers 5TOP, 5TOY, and 5VLE. © 2017 Federation of European Biochemical Societies.

  20. Mechanisms of proton relay and product release by Class A β-lactamase at ultrahigh resolution

    Energy Technology Data Exchange (ETDEWEB)

    Lewandowski, Eric M. [Department of Molecular Medicine, University of South Florida College of Medicine, Tampa FL USA; Lethbridge, Kathryn G. [Department of Molecular Medicine, University of South Florida College of Medicine, Tampa FL USA; Sanishvili, Ruslan [GMCA@APS, X-ray Science Division, Advanced Photon Source, Argonne National Laboratory, IL USA; Skiba, Joanna [Department of Organic Chemistry, Faculty of Chemistry, University of Lodz, Poland; Kowalski, Konrad [Department of Organic Chemistry, Faculty of Chemistry, University of Lodz, Poland; Chen, Yu [Department of Molecular Medicine, University of South Florida College of Medicine, Tampa FL USA

    2017-11-20

    The beta-lactam antibiotics inhibit penicillin-binding proteins (PBPs) by forming a stable, covalent, acyl-enzyme complex. During the evolution from PBPs to Class A beta-lactamases, the beta-lactamases acquired Glu166 to activate a catalytic water and cleave the acyl-enzyme bond. Here we present three product complex crystal structures of CTX-M-14 Class A beta-lactamase with a ruthenocene-conjugated penicillin-a 0.85 angstrom resolution structure of E166A mutant complexed with the penilloate product, a 1.30 angstrom resolution complex structure of the same mutant with the penicilloate product, and a 1.18 angstrom resolution complex structure of S70G mutant with a penicilloate product epimer-shedding light on the catalytic mechanisms and product inhibition of PBPs and Class A beta-lactamases. The E166A-penilloate complex captured the hydrogen bonding network following the protonation of the leaving group and, for the first time, unambiguously show that the ring nitrogen donates a proton to Ser130, which in turn donates a proton to Lys73. These observations indicate that in the absence of Glu166, the equivalent lysine would be neutral in PBPs and therefore capable of serving as the general base to activate the catalytic serine. Together with previous results, this structure suggests a common proton relay network shared by Class A beta-lactamases and PBPs, from the catalytic serine to the lysine, and ultimately to the ring nitrogen. Additionally, the E166A-penicilloate complex reveals previously unseen conformational changes of key catalytic residues during the release of the product, and is the first structure to capture the hydrolyzed product in the presence of an unmutated catalytic serine.

  1. When soils become sediments: Large-scale storage of soils in sandpits and lakes and the impact of reduction kinetics on heavy metals and arsenic release to groundwater.

    Science.gov (United States)

    Vink, Jos P M; van Zomeren, Andre; Dijkstra, Joris J; Comans, Rob N J

    2017-08-01

    Simulating the storage of aerobic soils under water, the chemical speciation of heavy metals and arsenic was studied over a long-term reduction period. Time-dynamic and redox-discrete measurements in reactors were used to study geochemical changes. Large kinetic differences in the net-complexation quantities of heavy metals with sulfides was observed, and elevated pore water concentrations remained for a prolonged period (>1 year) specifically for As, B, Ba, Co, Mo, and Ni. Arsenic is associated to the iron phases as a co-precipitate or sorbed fraction to Fe-(hydr)oxides, and it is being released into solution as a consequence of the reduction of iron. The composition of dissolved organic matter (DOM) in reducing pore water was monitored, and relative contributions of fulvic, humic and hydrophylic compounds were measured via analytical batch procedures. Quantitative and qualitative shifts in organic compounds occur during reduction; DOM increased up to a factor 10, while fulvic acids become dominant over humic acids which disappear altogether as reduction progresses. Both the hydrophobic and hydrophilic fractions increase and may even become the dominant fraction. Reactive amorphous and crystalline iron phases, as well as dissolved FeII/FeIII speciation, were measured and used as input for the geochemical model to improve predictions for risk assessment to suboxic and anaerobic environments. The release of arsenic is related to readily reducible iron fractions that may be identified by 1 mM CaCl 2 extraction procedure. Including DOM concentration shifts and compositional changes during reduction significantly improved model simulations, enabling the prediction of peak concentrations and identification of soils with increased emission risk. Practical methods are suggested to facilitate the practice of environmentally acceptable soil storage under water. Copyright © 2017 Elsevier Ltd. All rights reserved.

  2. Esterification of Oleic Acid for Biodiesel Production Catalyzed by SnCl2: A Kinetic Investigation

    Directory of Open Access Journals (Sweden)

    Marcio J. da Silva

    2008-09-01

    Full Text Available The production of biodiesel from low-cost raw materials which generally contain high amounts of free fatty acids (FFAs is a valuable alternative that would make their production costs more competitive than petroleum-derived fuel. Currently, the production of biodiesel from this kind of raw materials comprises a two-stage process, which requires an initial acid-catalyzed esterification of the FFA, followed by a basecatalyzed transesterification of the triglycerides. Commonly, the acid H2SO4 is the catalyst on the first step of this process. It must be said, however, that major drawbacks such as substantial reactor corrosion and the great generation of wastes, including the salts formed due to neutralization of the mineral acid, are negative and virtually unsurmountable aspects of this protocol. In this paper, tin(II chloride dihydrate (SnCl2·2H2O, an inexpensive Lewis acid, was evaluated as catalyst on the ethanolysis of oleic acid, which is the major component of several fat and vegetable oils feedstocks. Tin chloride efficiently promoted the conversion of oleic acid into ethyl oleate in ethanol solution and in soybean oil samples, under mild reaction conditions. The SnCl2 catalyst was shown to be as active as the mineral acid H2SO4. Its use has relevant advantages in comparison to mineral acids catalysts, such as less corrosion of the reactors and as well as avoiding the unnecessary neutralization of products. Herein, the effect of the principal parameters of reaction on the yield and rate of ethyl oleate production has been investigated. Kinetic measurements revealed that the esterification of oleic acid catalyzed by SnCl2·2H2O is first-order in relation to both FFAs and catalyst concentration. Experimentally, it was verified that the energy of activation of the esterification reaction of oleic acid catalyzed by SnCl2 was very close those reported for H2SO4.

  3. Etching kinetics of swift heavy ion irradiated silicone rubber with insoluble additives or reaction products

    International Nuclear Information System (INIS)

    Fink, D.; Mueller, M.; Petrov, A.; Farenzena, L.; Behar, M.; Papaleo, R.P.

    2003-01-01

    It is normally understood as a basic precondition of the etching of swift heavy ion tracks in polymers that both the additives and etching products are soluble in the etchant. If this is not given, the polymer surface may be gradually blocked by the deposition of the insoluble material that acts as a diffusion barrier for the penetration of fresh etchant into the tracks, and therefore the effective track etching speed will gradually be reduced. The etching kinetics is developed for that case, and the theory is compared with first experimental findings. For that purpose we have taken commercial silicone rubber foils as test materials, that were irradiated with GeV heavy ions through a mask at a fluence that corresponds to the onset of track overlapping. After etching with NaOH, the corresponding etching speed was recorded via the reduction of the foil thickness. The etching speed is seen to decrease with exposure time, in parallel to the development of an insoluble surface layer. It is discussed how to prevent that surface blocking, to maintain a high etching speed

  4. Efficient hydrogen production on MoNi4 electrocatalysts with fast water dissociation kinetics

    Science.gov (United States)

    Zhang, Jian; Wang, Tao; Liu, Pan; Liao, Zhongquan; Liu, Shaohua; Zhuang, Xiaodong; Chen, Mingwei; Zschech, Ehrenfried; Feng, Xinliang

    2017-05-01

    Various platinum-free electrocatalysts have been explored for hydrogen evolution reaction in acidic solutions. However, in economical water-alkali electrolysers, sluggish water dissociation kinetics (Volmer step) on platinum-free electrocatalysts results in poor hydrogen-production activities. Here we report a MoNi4 electrocatalyst supported by MoO2 cuboids on nickel foam (MoNi4/MoO2@Ni), which is constructed by controlling the outward diffusion of nickel atoms on annealing precursor NiMoO4 cuboids on nickel foam. Experimental and theoretical results confirm that a rapid Tafel-step-decided hydrogen evolution proceeds on MoNi4 electrocatalyst. As a result, the MoNi4 electrocatalyst exhibits zero onset overpotential, an overpotential of 15 mV at 10 mA cm-2 and a low Tafel slope of 30 mV per decade in 1 M potassium hydroxide electrolyte, which are comparable to the results for platinum and superior to those for state-of-the-art platinum-free electrocatalysts. Benefiting from its scalable preparation and stability, the MoNi4 electrocatalyst is promising for practical water-alkali electrolysers.

  5. EFFECT OF PRE-TREATMENT ON THE DRYING KINETICS AND PRODUCT QUALITY OF STAR FRUIT SLICES

    Directory of Open Access Journals (Sweden)

    CHING LIK HII

    2014-02-01

    Full Text Available Start fruit (Avverhoa carambola is rich in nutrients and contains dietary antioxidants which are beneficial to human health. Currently, the commercial potential of this fruit has not been fully explored especially in its dried form. The objectives of this research were to investigate the effect of pre-treatment on the drying kinetics and product quality of star fruit slices. The various pre-treatment methods investigated were hot water blanching and dipping in sugar solution. The star fruit was cut into thin slices (5 mm for drying (60°C-80°C using a hot air ventilated oven. Mathematical modelling showed that the Page model was able to describe the moisture diffusion process during drying. Effective diffusivity values were found within the order reported for most food materials (10-8-10-12 m2/s. A decreasing trend in shrinkage ratios was observed with decreasing moisture ratios which corresponds to the greater rate of moisture removal especially at the falling rate period. Overall colour changes were more significant in the blanched samples which could be due to the non-enzymatic browning.

  6. Kinetic studies and thermodynamics of oil extraction and transesterification of Chlorella sp. for biodiesel production.

    Science.gov (United States)

    Ahmad, A L; Yasin, N H Mat; Derek, C J C; Lim, J K

    2014-01-01

    In this work, a mixture of chloroform and methanol (1:1, v/v) was applied to oil extraction from Chlorella sp. at 30, 40, 50 and 60 degrees C for 150 min extraction times. Kinetic studies revealed that the values of n and the rate constants were found to depend strongly on temperature. The activation energy was Ea = 38.893 kJ/mol, and the activation thermodynamic parameters at 60 degrees C were ΔS≠ = -180.190 J/mol , ΔH≠ = 36.124k J/mol and ΔG≠ = 96.128k J/mol. Both ΔH and ΔS yielded positive values, whereas ΔG was negative at 60 degrees C, indicating that this process is endothermic, irreversible and spontaneous. The acidic transesterification process was also investigated by gas chromatographic analysis of the microalgae fatty acid methyl esters (biodiesel) at different temperatures and reaction times. The fatty acid profile indicated that the main components were palmitic, linoleic and linolenic acids. The concentration of linolenic acid increased and oleic acid decreased as the temperature increased. Two-hour transesterification is the best reaction time for biodiesel production because it produces the highest percentage of unsaturated fatty acids (74%). These results indicate the potential of Chlorella sp. to produce biodiesel of good quality.

  7. Prediction of Fission Product Release during the LOFC Experiments at the HTTR

    International Nuclear Information System (INIS)

    Shi, D.; Xhonneux, A.; Verfondern, K.; Ueta, S.; Allelein, H.-J.

    2014-01-01

    Demonstration tests were conducted using the High Temperature Engineering Test Reactor (HTTR) in Oarai, Japan, to confirm the safety of HTGR technologies and assure the expected physical phenomena to occur under given conditions. As part of the OECD directed LOFC (“loss of forced cooling”) project, a series of three tests at the HTTR has been planned with tripping of all gas circulators while deactivating all reactor reactivity control to disallow reactor scram due to abnormal reduction of primary coolant flow rate. The tests fall into anticipated transient without scram (ATWS) with occurrence of reactor recriticality. They serve the important purpose to provide a valuable data base for the validation of computer models regarding neutronics, heat transfer and fluid dynamics, fuel performance and fission product transport and release behavior in HTGRs. The Source Term Analysis Code System (STACY) is a new code development at the Research Center Jülich encompassing the original verified and validated computer models for simulating fission product transport and release. For verification of the modernized and extended version, it was assured that results obtained with the original tools could be reproduced. One of the new features of STACY is its ability to also treat fuel compacts of (full) cylindrical or annular shape and a complete prismatic block reactor core, respectively, supposed sufficient input data be available. The paper will describe the new STACY tool and present the results of fission product behavior in the HTTR core under the LOFC test conditions. Calculations are based on time-dependent neutronics and fluid dynamics results obtained with the Serpent and MGT models. (author)

  8. One-week glucose control via zero-order release kinetics from an injectable depot of glucagon-like peptide-1 fused to a thermosensitive biopolymer.

    Science.gov (United States)

    Luginbuhl, Kelli M; Schaal, Jeffrey L; Umstead, Bret; Mastria, Eric M; Li, Xinghai; Banskota, Samagya; Arnold, Susan; Feinglos, Mark; D'Alessio, David; Chilkoti, Ashutosh

    2017-01-01

    Stimulation of the glucagon-like peptide-1 (GLP1) receptor is a useful treatment strategy for type 2 diabetes because of pleiotropic effects, including the regulation of islet hormones and the induction of satiety. However, the native ligand for the GLP1 receptor has a short half-live owing to enzymatic inactivation and rapid clearance. Here, we show that a subcutaneous depot formed after a single injection of GLP1 recombinantly fused to a thermosensitive elastin-like polypeptide results in zero-order release kinetics and circulation times of up to 10 days in mice and 17 days in monkeys. The optimized pharmacokinetics leads to 10 days of glycemic control in three different mouse models of diabetes, as well as to the reduction of glycosylated hemoglobin levels and weight gain in ob/ob mice treated once weekly for 8 weeks. Our results suggest that the optimized GLP1 formulation could enhance therapeutic outcomes by eliminating peak-and-valley pharmacokinetics and improving overall safety and tolerability. The design principles that we established should be broadly applicable for improving the pharmacological performance of other peptide and protein therapeutics.

  9. Murmanite and lomonosovite as Ag-selective ionites: kinetics and products of ion exchange in aqueous AgNO3 solutions

    Science.gov (United States)

    Lykova, Inna S.; Chukanov, Nikita V.; Kazakov, Anatoliy I.; Tarasov, Viktor P.; Pekov, Igor V.; Yapaskurt, Vasiliy O.; Chervonnaya, Nadezhda A.

    2013-09-01

    Products and kinetics of ion exchange of heterophyllosilicate minerals lomonosovite and murmanite with aqueous AgNO3 solutions under low-temperature conditions have been studied using scanning electron microscopy, electron microprobe analysis, single-crystal X-ray diffraction, infrared spectroscopy, 23Na nuclear magnetic resonance spectroscopy and dynamic calorimetry. Both minerals show strong affinity for silver in cation exchange. Simplified formulae of Ag-exchanged forms of murmanite and lomonosovite are (Ag3.0Ca0.5Na0.5) (Ti,Nb,Mn,Fe)3.7-4 (Si2O7)2O4·4(H2O,OH) and (Ag8.2Na1.2Ca0.3) (Ti,Nb,Mn,Fe)3.9-4 (Si2O7)2 (PO4)1.9O4· xH2O, respectively. The reaction of ion exchange for murmanite follows the first-order kinetic model up to ca. 70-80 % conversion. The rate of the process is described by the equation k(h-1) = 107.64±0.60 exp[-(12.2 ± 0.9)·103/RT]. The average heat release value in the temperature range 39.4-72 °C is 230 J g-1. The cation exchange is limited by processes in solid state, most probably binding of silver.

  10. Life Cycle Assessment and Release Studies for 15 Nanosilver-Enabled Consumer Products: Investigating Hotspots and Patterns of Contribution.

    Science.gov (United States)

    Pourzahedi, Leila; Vance, Marina; Eckelman, Matthew J

    2017-06-20

    Increasing use of silver nanoparticles (AgNPs) in consumer products as antimicrobial agents has prompted extensive research toward the evaluation of their potential release to the environment and subsequent ecotoxicity to aquatic organisms. It has also been shown that AgNPs can pose significant burdens to the environment from life cycle emissions associated with their production, but these impacts must be considered in the context of actual products that contain nanosilver. Here, a cradle-to-gate life cycle assessment for the production of 15 different AgNP-enabled consumer products was performed, coupled with release studies of those same products, thus providing a consistent analytical platform for investigation of potential nanosilver impacts across a range of product types and concentrations. Environmental burdens were assessed over multiple impact categories defined by the United States Environmental Protection Agency's Tool for the Reduction and Assessment of Chemical and Other Environmental Impacts (TRACI 2.1) method. Depending on the product composition and silver loading, the contribution of AgNP synthesis to the overall impacts was seen to vary over a wide range from 1% to 99%. Release studies found that solid polymeric samples lost more silver during wash compared to fibrous materials. Estimates of direct ecotoxicity impacts of AgNP releases from those products with the highest leaching rates resulted in lower impact levels compared to cradle-to-gate ecotoxicity from production for those products. Considering both cradle-to-gate production impacts and nanoparticle release studies, in conjunction with estimates of life cycle environmental and health benefits of nanoparticle incorporation, can inform sustainable nanoenabled product design.

  11. Transformation of aminopyrine in the presence of free available chlorine: Kinetics, products, and reaction pathways.

    Science.gov (United States)

    Cai, Mei-Quan; Feng, Li; Zhang, Li-Qiu

    2017-03-01

    Aminopyrine (AMP) has been frequently detected in the aquatic environment. In this study, the transformation mechanism of AMP by free available chlorine (FAC) oxidation was investigated. The results showed that FAC reacted with AMP rapidly, and a 74% elimination was achieved for 1.30 μM AMP after 2 min at 14.08 μM FAC dose. AMP chlorination was strongly pH-dependent, and its reaction included second- and third-order kinetic processes. Three active FAC species, including chlorine monoxide (Cl 2 O), molecular chlorine (Cl 2 ), and hypochlorous acid (HOCl), were observed to contribute to AMP degradation. The intrinsic rate constants of each FAC species with neutral (AMP 0 ) and cation (AMP + ) species were obtained by kinetic fitting. Cl 2 O exhibited the highest reactivity with AMP 0 (k AMP0, Cl2O  = (4.33 ± 1.4) × 10 9  M -1 s -1 ). In addition, Cl 2 showed high reactivity (10 6 -10 7  M -1 s -1 ) in the presence of chloride, compared with HOCl (k AMP+, HOCl  = (5.73 ± 0.23) × 10 2  M -1 s -1 , k AMP0, HOCl  = (9.68 ± 0.96) × 10 2  M -1 s -1 ). At pH 6.15 and 14.08 μM FAC dose without chloride addition, the contribution of Cl 2 O reached to the maximum (33.3%), but in the whole pH range, HOCl was the main contributor (>66.6%) for AMP degradation. The significance of Cl 2 was noticeable in water containing chloride. Moreover, 11 transformation products were identified, and the main transformation pathways included pyrazole ring breakage, hydroxylation, dehydrogenation, and halogenation. Copyright © 2016 Elsevier Ltd. All rights reserved.

  12. Environmental Impacts by Fragments Released from Nanoenabled Products: A Multiassay, Multimaterial Exploration by the SUN Approach.

    Science.gov (United States)

    Amorim, Mónica J B; Lin, Sijie; Schlich, Karsten; Navas, José M; Brunelli, Andrea; Neubauer, Nicole; Vilsmeier, Klaus; Costa, Anna L; Gondikas, Andreas; Xia, Tian; Galbis, Liliana; Badetti, Elena; Marcomini, Antonio; Hristozov, Danail; Kammer, Frank von der; Hund-Rinke, Kerstin; Scott-Fordsmand, Janeck J; Nel, André; Wohlleben, Wendel

    2018-02-06

    Nanoenabled products (NEPs) have numerous outdoor uses in construction, transportation or consumer scenarios, and there is evidence that their fragments are released in the environment at low rates. We hypothesized that the lower surface availability of NEPs fragment reduced their environmental effects with respect to pristine nanomaterials. This hypothesis was explored by testing fragments generated by intentional micronisation ("the SUN approach"; Nowack et al. Meeting the Needs for Released Nanomaterials Required for Further Testing: The SUN Approach. Environmental Science & Technology, 2016 (50), 2747). The NEPs were composed of four matrices (epoxy, polyolefin, polyoxymethylene, and cement) with up to 5% content of three nanomaterials (carbon nanotubes, iron oxide, and organic pigment). Regardless of the type of nanomaterial or matrix used, it was observed that nanomaterials were only partially exposed at the NEP fragment surface, indicating that mostly the intrinsic and extrinsic properties of the matrix drove the NEP fragment toxicity. Ecotoxicity in multiple assays was done covering relevant media from terrestrial to aquatic, including sewage treatment plant (biological activity), soil worms (Enchytraeus crypticus), and fish (zebrafish embryo and larvae and trout cell lines). We designed the studies to explore the possible modulation of ecotoxicity by nanomaterial additives in plastics/polymer/cement, finding none. The results support NEPs grouping by the matrix material regarding ecotoxicological effect during the use phase. Furthermore, control results on nanomaterial-free polymer fragments representing microplastic had no significant adverse effects up to the highest concentration tested.

  13. TRAFIC, a computer program for calculating the release of metallic fission products from an HTGR core

    International Nuclear Information System (INIS)

    Smith, P.D.

    1978-02-01

    A special purpose computer program, TRAFIC, is presented for calculating the release of metallic fission products from an HTGR core. The program is based upon Fick's law of diffusion for radioactive species. One-dimensional transient diffusion calculations are performed for the coated fuel particles and for the structural graphite web. A quasi steady-state calculation is performed for the fuel rod matrix material. The model accounts for nonlinear adsorption behavior in the fuel rod gap and on the coolant hole boundary. The TRAFIC program is designed to operate in a core survey mode; that is, it performs many repetitive calculations for a large number of spatial locations in the core. This is necessary in order to obtain an accurate volume integrated release. For this reason the program has been designed with calculational efficiency as one of its main objectives. A highly efficient numerical method is used in the solution. The method makes use of the Duhamel superposition principle to eliminate interior spatial solutions from consideration. Linear response functions relating the concentrations and mass fluxes on the boundaries of a homogeneous region are derived. Multiple regions are numerically coupled through interface conditions. Algebraic elimination is used to reduce the equations as far as possible. The problem reduces to two nonlinear equations in two unknowns, which are solved using a Newton Raphson technique

  14. HTR fuel modelling with the ATLAS code. Thermal mechanical behaviour and fission product release assessment

    International Nuclear Information System (INIS)

    Guillermier, Pierre; Daniel, Lucile; Gauthier, Laurent

    2009-01-01

    To support AREVA NP in its design on HTR reactor and its HTR fuel R and D program, the Commissariat a l'Energie Atomique developed the ATLAS code (Advanced Thermal mechanicaL Analysis Software) with the objectives: - to quantify, with a statistical approach, the failed particle fraction and fission product release of a HTR fuel core under normal and accidental conditions (compact or pebble design). - to simulate irradiation tests or benchmark in order to compare measurements or others code results with ATLAS evaluation. These two objectives aim at qualifying the code in order to predict fuel behaviour and to design fuel according to core performance and safety requirements. A statistical calculation uses numerous deterministic calculations. The finite element method is used for these deterministic calculations, in order to be able to choose among three types of meshes, depending on what must be simulated: - One-dimensional calculation of one single particle, for intact particles or particles with fully debonded layers. - Two-dimensional calculations of one single particle, in the case of particles which are cracked, partially debonded or shaped in various ways. - Three-dimensional calculations of a whole compact slice, in order to simulate the interactions between the particles, the thermal gradient and the transport of fission products up to the coolant. - Some calculations of a whole pebble, using homogenization methods are being studied. The temperatures, displacements, stresses, strains and fission product concentrations are calculated on each mesh of the model. Statistical calculations are done using these results, taking into account ceramic failure mode, but also fabrication tolerances and material property uncertainties, variations of the loads (fluence, temperature, burn-up) and core data parameters. The statistical method used in ATLAS is the importance sampling. The model of migration of long-lived fission products in the coated particle and more

  15. Necroptotic cells release find-me signal and are engulfed without proinflammatory cytokine production.

    Science.gov (United States)

    Wang, Qiang; Ju, Xiaoli; Zhou, Yang; Chen, Keping

    2015-11-01

    Necroptosis is a form of caspase-independent programmed cell death which is mediated by the RIP1-RIP3 complex. Although phagocytosis of apoptotic cells has been extensively investigated, how necroptotic cells are engulfed has remained elusive. Here, we investigated how necroptotic cells attracted and were engulfed by macrophages. We found that necroptotic cells induced the migration of THP-1 cells in a transwell migration assay. Further analysis showed that ATP released from necroptotic cells acted as a find-me signal that induced the migration of THP-1 cells. We also found that Annexin V blocked phagocytosis of necroptotic cells by macrophages. Furthermore, necroptotic cells were shown to be silently cleared by macrophages without any proinflammatory cytokine production. These data uncover an evolutionarily conserved mechanism of the find-me signal in different types of cell death and immunological consequences between apoptotic and necroptotic cells during phagocytosis.

  16. Integrated Scheduling of Production and Distribution with Release Dates and Capacitated Deliveries

    Directory of Open Access Journals (Sweden)

    Xueling Zhong

    2016-01-01

    Full Text Available This paper investigates an integrated scheduling of production and distribution model in a supply chain consisting of a single machine, a customer, and a sufficient number of homogeneous capacitated vehicles. In this model, the customer places a set of orders, each of which has a given release date. All orders are first processed nonpreemptively on the machine and then batch delivered to the customer. Two variations of the model with different objective functions are studied: one is to minimize the arrival time of the last order plus total distribution cost and the other is to minimize total arrival time of the orders plus total distribution cost. For the former one, we provide a polynomial-time exact algorithm. For the latter one, due to its NP-hard property, we provide a heuristic with a worst-case ratio bound of 2.

  17. Radioecological studies of activation products released from a nuclear power plant into the marine environment

    International Nuclear Information System (INIS)

    Mattsson, S.; Nilsson, M.; Holm, E.

    1980-01-01

    Since 1967 samples of Fucus serratus and Fucus vesi--culosus from the Swedish west-coast were collected for analysis of the concentration of fallout products, natural actinides and products released by the nuclear industry. During this time two nuclear power stations were built and began operation in this area, ''Ringhals'' in 1974 and ''Barseback'' in 1975. When detectable concentrations of Co-60 and other activation products were found in Fucus, the sampling program was intensified, both in the vicinity of ''Barseback'' and at localities up to 150 km north. Our studies have shown that measurements on Fucus can be used to map the distribution of various radionuclides from a nuclear power station in the marine environment. Knowl