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Synthesis of structured phospholipids by immobilized phospholipase A2 catalyzed acidolysis
2007-01-01
Acyl modification of the sn-2 position in phospholipids (PLs) was conducted by acidolysis reaction using immobilized phospholipase A2 (PLA2) as the catalyst. In the first stage we screened different carriers for their ability to immobilize PLA2. Several carriers were able to fix the enzyme and maintain catalytic activity; however, the final choice of carrier for the continued work was a non-ionic weakly polar macroreticular resin. Response surface methodology was applied to evaluate the influence of substrate ratio, reaction temperature, and water addition during acidolysis reaction between caprylic acid and soybean phosphatidylcholine (PC). Reaction temperature and water addition had significant effect on acidolysis reaction, however no effect was observed for substrate ratio (mol capryli...
Synthesis of structured phospholipids by immobilized phospholipase A2 catalyzed acidolysis
2007-01-01
Acyl modification of the sn-2 position in phospholipids (PLs) was conducted by acidolysis reaction using immobilized phospholipase A2 (PLA2) as the catalyst. In the first stage we screened different carriers for their ability to immobilize PLA2. Several carriers were able to fix the enzyme and maintain catalytic activity; however the final choice of carrier for the continued work was a non-ionic weakly polar macroreticular resin. Response surface methodology was applied to evaluate the influence of substrate ratio, reaction temperature and water addition during acidolysis reaction between caprylic acid and soybean phosphatidylcholine (PC). Reaction temperature and water addition had significant effect on acidolysis reaction, however no effect was observed for substrate ratio (mol caprylic acid/mol PC) in range tested. In general an inverse relationship between incorporation of caprylic acid and PC recovery was observed. Highest incorporation obtained during acidolysis reactions was 36%. Such incorporation could be obtained under reaction temperature, 45°C; substrate ratio, 9 mol/mol caprylic acid/PC; and water addition of 2%; 30 wt % immobilized enzyme; and reaction time, 48h. The yield under these conditions was however only 29%. Lysophosphatidylcholine (LPC) was the major by-product formed during the reaction. Incorporation of acyl donor into LPC was very low (
Synthesis of structured phospholipids by immobilized phospholipase A2 catalyzed acidolysis
2007-01-01
Synthesis of structured phospholipids by immobilized phospholipase A2 catalyzed acidolysis
2007-01-01
axion: Axion - Java Database - News
The Axion news feed is on hiatus, yet Axion is still being actively developed. ... Better late than never, it's the Axion database project's October 2003 ...
A small, fast, SQL and JDBC compliant relational database engine written in and for the Java programming language. [Open source, BSD License]
XPS analysis of boron doped heterofullerenes
1997-06-01
Boron heterofullerenes were generated through arc-evaporation of doped graphite rods in a helium atmosphere. According to mass spectrometric analysis only mono-substituted fullerenes like C{sub 59}B, C{sub 69}B and higher homologues together with a large fraction of higher undoped fullerenes were extracted and enriched when pyridine was used as the solvent. XPS analysis of the extracts indicated the presence of two boron species with significantly different binding energies. One peak was assigned to borid acid. The second one corresponds to boron in the fullerene cage, which is mainly C{sub 59}B, according to the mass spectrum. This boron is in a somewhat higher oxidation state than that of ordinary boron-carbon compounds. The reported synthesis and extraction procedure opens a viable route for production of macroscopic amounts of these compounds. (author) 2 figs., 1 tab., 7 refs.
Wuestite - a solar energy carrier
1997-06-01
Hydrogen is produced when Wuestite (Fe{sub 1-y}O) is oxidised by water. This reaction is part of a two-step thermochemical metal oxide cycle for the storage of solar energy in the form of chemical energy carriers, characterised by a high chemical potential. The reaction was studied in a tubular furnace with on-line gas analysis and further characterised in detail by DTA und high-temperature X-ray powder diffraction. The influence of non-stoichiometry, morphology and temperature on the mechanism and kinetics of the water-splitting reaction was determined. (author) 3 figs., tabs., 3 refs.
The National Cancer Institute (NCI) has the vital mission of facilitating the process by which cancer research is communicated to the public. The task of collecting data relevant to cancer communication falls on the Health Communication and Informatics Research Branch (HCIRB), Division of Cancer Control and Population Science (DCCPS) at NCI.
1997-06-01
Oxidation of CO over palladium/zirconia catalyst obtained from an amorphous Pd{sub 25}Zr{sub 75} precursor was investigated by time resolved FTIR spectroscopy. Sine wave shaped modulation of the reactant concentration, i.e. variation of CO or O{sub 2} partial pressure, was used to induce variations of the IR signals of product (CO{sub 2}) and unconverted reactant (CO), which were detected in a multi-pass absorption cell. The phase shift {phi} between external perturbation and variation of the CO{sub 2} signal was examined in dependence on temperature (100{sup o}C{<=}T{<=}350{sup o}C) and modulation frequency (1.39x10{sup -4}Hz{<=}{omega}{<=}6.67x10{sup -2}Hz). From the phase shift values, a simple Eley-Rideal mechanism is excluded, and the rate limiting step of the Langmuir-Hinshelwood mechanism for the CO oxidation may be identified. Adsorption and possible surface movement of CO to the actual reaction site determine the rate of the CO oxidation on the palladium/zirconia catalyst used in our study. The introduction of an external perturbation is a first step towards the application of two-dimensional infrared spectroscopy to heterogeneous catalyzed reactions. (author) 3 figs., 4 refs.
Thermal stability of nafion membranes under mechanical stress
1997-06-01
The feasibility of adequately modified fluoro-ionomer membranes (NAFION{sup R}) is demonstrated for the selective separation of methanol synthesis products from the raw reactor gas at temperatures around 200{sup o}C. For an economically relevant application of this concept on a technical scale the Nafion membranes should be thin ({approx_equal}10 {mu}m) and thermally stable over a long period of time (1-2 years). In cooperation with industry (Methanol Casale SA, Lugano (CH)), we test the thermal stability of Nafion hollow fibers and supported Nafion thin sheet membranes at temperatures between 160 and 200{sup o}C under mechanical stress by applying a gas pressure difference over the membrane surface ({Delta}P{<=} 40 bar). Tests with the hollow fibers revealed that Nafion has visco-elastic properties. Tests with 50 {mu}m thin Nafion sheets supported by a porous metal carrier at 200{sup o}C and {Delta}P=39 bar showed no mechanical defects over a period of 92 days. (author) 5 figs., 4 refs.
The novel phenomenon of noise-catalyzed chaos-order transitions
1997-06-01
Numerical simulations of the Lorenzian water wheel have been used to investigate the influence of stochastic noise on the lifetime of chaotic transients. Whereas in one region of parameter space no noise dependency could be detected, a shortening of the lifetimes by more than four decades was found in another region. This large effect was produced by a significant modification of the attraction basin of a quasistable stationary state rather than by affecting the chaotic orbits before the chaos-order transition occurred. This novel phenomenon of noise-induced chaos-order transitions is not related to stochastic resonance or other noise-induced effects. (author) 2 figs., 5 refs.
The influence of chlorine on the gasification of wood
1997-06-01
Chlorides of the heavy metals copper, lead and zinc inhibit the CO{sub 2}-gasification reaction of charcoal. This is observed either by impregnation the wood with the salts before pyrolysis or by mechanically mixing the salts with the charcoal before gasification. Charcoal impregnated or mixed with ammonium chloride reacts more slowly than untreated charcoal. Treating the charcoal with HCl also influences negatively the gasification reactivity, indicating that chlorine plays an important role in the gasification. (author) 2 figs., 4 refs.
TUS-CPS series: Vietnamese Translation Computer-Assisted Interview Instrument
vietnAmese Computer-Assisted interview instrument re?ised Fall 2005 A downloadable version of this document, and of other translations of the 2003 Tobacco Supplement to the Current Population Surve?, ma? be obtained from http://riskfactor.cancer.gov/studies/tus-cps/translation/ This
Solid state diffusion and reaction in ZnO/SiO{sub 2} in thin films
1997-06-01
Detoxification of fly ash from waste incineration by evaporating harmful heavy metals is limited by the formation of stable heavy metal-matrix compounds. To study the rate of these heavy metal-matrix reactions, experiments were performed with the diffusion couple ZnO (heavy metal)-SiO{sub 2} (matrix). The atomic concentration profiles after different annealing treatments were analysed by X-ray photoelectron spectroscopy (XPS). (author) 3 figs., 4 refs.
Recycling of greenhouse gases via methanol
1997-06-01
Greenhouse gas emissions to the atmosphere can be mitigated by using direct control technologies (capture, disposal or chemical recycling). We report on carbon dioxide and methane recycling with other chemicals, especially with hydrogen and oxygen, to methanol. Methanol synthesis from CO{sub 2} is investigated on various catalysts at moderate pressures ({<=}30 bar) and temperatures ({<=}300{sup o}C). The catalysts show good methanol activities and selectivities. The conversion of CO{sub 2} and CH{sub 4} to methanol is also studied in a silent electrical discharge at pressures of 1 to 4 bar and temperatures close to room temperature. Methanol yields are given for mixtures of CO{sub 2}/H{sub 2}, CH{sub 4}/O{sub 2} and also for CH{sub 4} and air mixtures. (author) 2 figs., 5 refs.
Prostate Cancer Treatment (PDQ®) (Health Professional)
Expert-reviewed information summary about the treatment of prostate cancer.
Production of filamentous carbon and H{sub 2} by solarthermal catalytic cracking of CH{sub 4}
1997-06-01
The catalytic thermal decomposition of methane has been experimentally studied using high-temperature solar process heat. Nickel catalyst particles, fluidized in methane, were directly irradiated at the PSI solar furnace. Carbon deposition consisted of randomly interlaced filaments that grew as fibers and hollow nanotubes (of approx. 30 nm diameter) originating at each catalytic particle. (author) 4 figs., 7 refs.
Photochemistry at high temperatures - potential of ZnO as a high temperature photocatalyst
1997-06-01
Direct conversion of solar radiation into useful, storeable and transportable chemical products is the primary goal of solar chemistry. In this paper we discuss some fundamental aspects of photochemistry at elevated temperatures. We show that luminescence can serve as an indicator of the potential use of a system as a photoconverter. As an example we present experimental data on the chemical potential and on the lifetime of the excited states of ZnO. The low luminescence quantum yield together with a lifetime of about 200 ps indicate that an efficient photochemical conversion on ZnO is highly improbable. We believe this to be a general feature of chemical systems based on a semiconductor photocatalyst, in particular of photoreactions at a solid/gas interface. (author) 3 figs., 6 refs
Montreal Axion - Wikipedia, the free encyclopedia
The Montreal Axion are a National Women's Hockey League team located in Montreal, Quebec, Canada. v ? d ? e · Sports teams based in the province of Quebec, ...
Microstructuring of triazene containing copolyester films
1997-06-01
The growing field of microtechnology has an increasing demand for affordable functional materials. Several strategies exist for improving the ablation behaviour of standard polymers. One is the copolymerization of a standard commercial polymer with a specialty polymer, in our case of a polyester and triazene group containing polyester. For comparison of the copolymers with different fractions of triazene groups we have determined the threshold fluences and the effective absorption coefficients. With respect to these ablation parameters, only small differences were found within the set of copolymers investigated. Only with AFM and SEM it was possible to detect that a minimum content of triazene groups is necessary for defined microstructure with sharp edges, whereby a resolution in the sub {mu}m scale has been achieved. (author) 4 figs., 1 tab., 5 refs.
Figure 6.2 Three-Factor Latent Phenotype Model A C E 1.0 1.0 1.0 aF1 eF1 cF1 F1 A C E 1.0 1.0 1.0 aF3 eF3 cF3 F3 A C E 1.0 1.0 1.0 aF2 eF2 cF2 F2 P1T1 P2T1 P3T1 P4T1 P5T1 C E A C E A C E A C E A C EA 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0 Note.
In the 7 years since the EPA report was published, the evidence that ETS causes lung cancer and other serious diseases has continued to accumu-late. Lung cancer was the first fatal disease linked to ETS, but in recent years, evidence that ETS exposure causes other major diseases?particularly heart disease?has emerged.
Kinetics with deactivation of methylcyclohexane dehydrogenation for hydrogen energy storage
1997-06-01
The methylcyclohexane dehydrogenation step to recycle toluene and release hydrogen is being studied as part of a hydrogen energy storage project. The reaction is performed catalytically in a fixed bed reactor, and the efficiency of this step significantly determines overall system economics. The fresh catalyst kinetics and the deactivation of the catalyst by coke play an important role in the process analysis. The main reaction kinetics were determined from isothermal experiments using a parameter sensitivity analysis for model discrimination. An activation energy for the main reaction of 220{+-}11 kJ/mol was obtained from a two-parameter model. From non-isothermal deactivation in PC-controlled integral reactors, an activation energy for deactivation of 160 kJ/mol was estimated. A model for catalyst coke content of 3-17 weight% was compared with experimental data. (author) 3 figs., 6 refs.
Intermittent contact atomic force microscopy in electrochemical environment
1997-06-01
In situ measurements with Atomic Force Microscopy may cause surface modifications due to the tip-surface interactions. As an alternative and less destructive method, Intermittent Contact Atomic Force Microscopy (ICAFM) has been tested in an electrolytic environment. In the ICAFM mode the tip is not constantly in contact with the surface under investigation but is tapping onto the surface with a certain frequency. A commercial Park Scientific Instruments Microscopy has been modified to enable in situ experiment with ICAFM. It was possible to image iridium oxide films with ICAFM in the electrolytic environment without any noticeable surface modifications. (author) 3 figs., 4 refs.
In-situ investigation of the calcination process of mixed oxide xerogels with Raman spectroscopy
1997-06-01
The controlled calcination of materials derived by sol-gel reactions is important for the evolution of the final structure. Raman spectroscopy is an ideal tool for the identification of surface species under in-situ conditions, as demonstrated in the following for the example of a molybdenum oxide-silica xerogel. Raman spectra of this particular sample were recorded at temperatures as high as 1173 K, and compared with those of a reference material.(author) 3 figs., 4 refs.
Gasification of wood in a fluidized bed reactor
1997-06-01
A first series of gasification experiments with our fluidized bed gasifier was performed using clean sawdust as fuel. The installation and the analytical systems were tested in a parametric study in which gasification temperature and equivalence ratio were varied. The data acquired will serve to establish the differences between the gasification of clean wood and the gasification of Altholz (scrapwood) and wood/plastics mixtures. (author) 1 fig., 3 tabs., 5 refs.
Development and characterization of a rare earth emitter for a thermophotovoltaic power generator
1997-06-01
Energy conversion based on thermophotovoltaic (TPV) methods has recently attracted renewed interest. Efforts at PSI are directed towards the development of a modular TPV system based on existing technology to demonstrate the feasibility of this method. Here, we report first results obtained with a prototype TPV generator based upon a modified rare earth emitter, a heat reflecting filter and commercial silicon solar cells. The preparation of the modified emitter is described, and first results of spectroscopic and electrical characterization of the TPV system are presented. The introduction of the modified emitter leads to an efficiency gain of 30-40%. (author) 3 figs., 4 refs.
Cáncer de la próstata: Tratamiento (PDQ®) (Health Professional)
Resumen de información revisada por expertos acerca del tratamiento del cáncer de la próstata.
Full Text Available.BackgroundWax esters are important ingredients in cosmetics, pharmaceuticals, lubricants and other chemical industries due to their excellent wetting property. Since the naturally occurring wax esters are expensive and scarce, these esters can be produced by enzymatic alcoholysis of vegetable oils. In an enzymatic reaction, study on modeling and optimization of the reaction system to increase the efficiency of the process is very important. The classical method of optimization involves varying one parameter at a time that ignores the combined interactions between physicochemical parameters. RSM is one of the most popular techniques used for optimization of chemical and biochemical processes and ANNs are powerful and flexible tools that are well suited to modeling biochemical processes.ResultsThe coefficient of determination (R2) and absolute average deviation (AAD) values between the actual and estimated responses were determined as 1 and 0.002844 for ANN training set, 0.994122 and 1.289405 for ANN test set, and 0.999619 and 0.0256 for RSM training set respectively. The predicted optimum condition was: reaction time 7.38 h, temperature 53.9°C, amount of enzyme 0.149 g, and substrate molar ratio 1:3.41. The actual experimental percentage yield was 84.6% at optimum condition, which compared well to the maximum predicted value by ANN (83.9%) and RSM (85.4%). The order of effective parameters on wax ester percentage yield were; respectively, time with 33.69%, temperature with 30.68%, amount of enzyme with 18.78% and substrate molar ratio with 16.85%, whereas R2 and AAD were determined as 0.99998696 and 1.377 for ANN, and 0.99991515 and 3.131 for RSM respectively.ConclusionThough both models provided good quality predictions in this study, yet the ANN showed a clear superiority over RSM for both data fitting and estimation capabilities.
BackgroundWax esters are important ingredients in cosmetics, pharmaceuticals, lubricants and other chemical industries due to their excellent wetting property. Since the naturally...Full Text Available
Combined coal gasification and Fe{sub 3}O{sub 4}-reduction using high-temperature solar process heat
1997-06-01
The coal/Fe{sub 3}O{sub 4} system was experimentally studied at PSI solar furnace. The reactants were directly exposed to a solar flux irradiation of 3,000 suns (1 sun = 1 kW/m{sup 2}). The combined gasification of coal and reduction of Fe{sub 2}O{sub 3} proceeded rapidly after only one second exposure, suggesting an efficient heat transfer and chemical conversion by direct solar energy absorption at the reaction site. The proposed solar thermochemical process offers the possibility of converting coal to a cleaner fluid fuel with a solar-upgraded calorific value. (author) 2 figs., 8 refs.
Center for Cancer Research - Staff Pages
Dr. Stuart Le Grice received his Ph.D. from the Department of Biochemistry, University of Manchester, UK, in 1976, where he studied the mechanisms of R-factor-mediated multidrug resistance in Escherichia coli. After postdoctoral training in the United Kingdom, Germany, and the United States, he was appointed Senior Scientist in the Central Research Units of Hoffmann La Roche, Basel, Switzerland, where he worked from 1984 to 1990 evaluating HIV-1 and HIV-2 enzymes as therapeutic targets.
2006-10-15
Aim of this thesis was the preparation and evaluation of phosphonated high performance (HP) polyelectrolytes and polyhedral oligomeric silsesquioxanes (POSS) for polyelectrolyte membrane fuel cell (PEMFC) application. Brominated derivatives of the commercial high performance (HP) polymers poly(ethersulfone) (PES), poly(etheretherketone) (PEEK), poly(phenylsulfone) (PPSu), poly(sulfone) (PSU) and of octaphenyl-POSS of own production were phosphonated by Ni-catalysed Arbuzov reaction. Phosphonated PSU was cast into pure and blend films with sulfonated PEEK (s-PEEK) to investigate H+-conductivity, water uptake and film morphology. Blend films' properties were referenced to films containing unmodified blend partners. Solution-compounding of phosphonated octaphenyl-POSS and s-PEEK was used to produce novel nanocomposite films. An in-situ zirconisation method was assessed as convenient strategy for novel ionically crosslinked membranes of enhanced swelling resistance. Dibromo isocyanuric acid (DBI) and N-bromo succinimide (NBS) as brominating agents allowed polymer analogous preparation of the novel brominated PES and PEEK with precise reaction control. A random distribution of functional groups, i.e. polyelectrolytes' microstructural homogeneity was revealed as decisive factor concerning solubility of phosphonated PSU. Brominated phT8 was prepared with Br2 by a high temperature approach in tetrachloroethane (TCE). Brominated polymers were phosphonated by Ni-catalysis in non-coordinating high temperature solvents, such as diphenylether, benzophenone and diphenylsulfone without notable solvent influence. The lack of solvent - catalyst complexes and high reaction temperatures of 180-200 C led to halogen-free phosphonates with unprecedented high functionalities. Polymer analogous application of P(OSiMe3)3 offered a novel direct access to easily cleavable disilyl ester derivatives. These were obtained from PEEK and PSU in near quantitative yields at NiCl2-loads as low as 1 mol-% per bromine. The developed approach's low catalyst demand, high yield, bromine-free products and wide range of applicable substrates greatly improves on existing polymer analogous methods. Good solubility of phosphonated polyelectrolytes was observed for phosphonated PSU, which was NMP-miscible up to a degree of phosphonation dsP=102 mol% (Reduct=alkyl) and 223 mol-% (Reduct=SiMe3). TGA of phosphonated derivatives showed backbone stability in air to 325-400 C, while SO3H-derivatives desulfonated at 180-330 C. Film casting of phosphonated PSU with dsP = 41-102 mol% gave flexible and stable membranes with H+-conductivities of {sigma}=1,2-8,7 mS/cm at 25 C. The polar interaction of PO3H2-groups led to a negligible mass swelling of swM=5,1-9,8 wt-% and a negative area swelling of swA=-4 A% in water at 80 C. Such unrivalled beneficial combination of properties suggest excellent applicability of phosphonated polyelectrolytes as membrane material in DMFC.
Bipolar zinc/oxygen battery development
1997-06-01
A bipolar electrically rechargeable Zn/O{sub 2} battery has been developed. Reticulated copper foam served as substrate for the zinc deposit on the anodic side, and La{sub 0.6}Ca{sub 0.4}CoO{sub 3}-catalyzed bifunctional oxygen electrodes were used on the cathodic side of the cells. The 100 cm{sup 2} unit cell had an open circuit voltage of 1,4 V(O{sub 2}) in moderately alkaline electrolyte. The open circuit voltage and the peak power measured for a stack containing seven cells were ca. 10V and 90W, respectively. The current-potential behaviour was determined as a function of the number of bipolar cells, and the maximum discharge capacity was determined at different discharge rates. (author) 4 figs., 1 ref.
Azo group containing compounds: investigation of the decay mechanism
1997-06-01
We investigated compounds containing the N=N-X (X=S,P,N{sub 3}) group which are potential candidates for microstructuring by photoresist technology or by photoablation. To elucidate the mechanism of thermal decomposition and photolysis we used infrared and UV spectroscopy, respectively, in solution as well as in the solid state. In this article we describe photolytic and thermolytic properties of one representative molecule for each of three substance classes: diazosulfides, azophosphonates and pentazadienes. (author) 4 figs., 4 refs.
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Axion Project Incubation Status - Apache Incubator
For general project status, see the Axion project website. ... The axion project never moved to the ASF from tigris.org. 2003-12-19: The Apache Incubator ...
Axion - Wikipedia, the free encyclopedia
The axion is a hypothetical elementary particle postulated by Peccei-Quinn theory in 1977 to resolve the strong-CP problem in quantum chromodynamics (QCD). ...
Robert T. Croyle, Ph.D. Director, Division of Cancer Control and Population Sciences References 1. Anthonisen, N. R., M. A. Skeans, R. A. Wise, J. Manfreda, R. E. Kanner, and J. E. Connett.
National Strategy to Prevent and Control Tobacco Use? ......................................................... 414 Appendix 9.C. Helene Brown Testimony .................................................................................. 418 Commitment to Fund Effective Tobacco Control ..................................................................... 421 386 M o n o g r a p h 1 6. A S S I S T 9.
2003 Tobacco Use Supplement File: Technical Documentation CPS-03
ATTACHMENT 2 OVERVIEW Current Population Survey Introduction The Current Population Survey (CPS) is the source of the official government statistics on employment and unemployment.
A reproducible, high-yield synthesis of mono([8]annulene)uranium(4)dichloride (1) is reported, along with the X-ray crystal structural of the bis(pyridine) adduct. Metathesis reactions of the half-sandwich complex 1 with a variety of simple alkyl and alkoxy reagents failed to generate any isolable mono-ring complexes. Reactions of 1 with polydentate, delocalized anions did produce stable derivatives, including mono([8]annulene)uranium(4)bis(acetylacetonate) (4). An X-ray crystal structure of 4 is reported.
A reproducible, high-yield synthesis of mono((8)annulene)uranium(4)dichloride (1) is reported, along with the X-ray crystal structural of the bis(pyridine) adduct. Metathesis reactions of the half-sandwich complex 1 with a variety of simple alkyl and alkoxy reagents failed to generate any isolable mono-ring complexes. Reactions of 1 with polydentate, delocalized anions did produce stable derivatives, including mono((8)annulene)uranium(4)bis(acetylacetonate) (4). An X-ray crystal structure of 4 is reported.
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