Formation of oxidizing and reducing radicals was studied by pulse radiolysis of [Fe(CN)_6]"4"- - BrO_3"- - CN"- system in ethylene glycol - water solvent mixture. Oxidizing #centre dot#BrO_2 and BrO radicals formed by electron scavenging with #centre dot#BrO_2"- were identified and their reactions were investigated. The reaction of hydroxyl radicals with ethylene glycol leads to formation of reactive radicals with reducing properties and of compounds which reduce slowly in dark the ferricyanide formed in the reaction of #centre dot#BrO_2 radical with ferrocyanide. (author) 21 refs.; 7 figs.
Abstract Green tea extract showed false-negative results in the determination of glucose via glucose oxidase (GOD) test. This investigation was undertaken to verify and find out the precise mechanism underlying this interference by determining the reaction kinetics of production and reduction of end-point chromophore. The peroxidase step of the GOD test was found to be interfered and phenols of the green tea were the interfering compounds. Green tea interfered and exerted its influence in a dual fashion. A part of the interference was observed as a result of the reduction of the finally formed chromophore, whereas the other form of interference was due to its hydrogen peroxide/free radical-scavenging activity. Reducing potential and the free radical-scavenging activity of the phenols in th...
The reactions of native bovine catalase with superoxide and solvated electrons have been investigated using three different methods for generating these reducing substrates: [gamma]-radiolysis of oxygenated or deaerated buffer solutions in the presence of an OH radicalscavenger; either xanthine or acetaldehyde with xanthine oxidase; and low-temperature (77 K) [gamma]-radiolysis of buffered ethylene glycol/water solutions with subsequent annealing of samples at 183 K. (Author).
The extracts from kinnow peel, kinnow seeds, litchi pericarp, litchi seeds, grape seeds, and banana peel were screened for total phenolic content (TPC), trolox equivalent antioxidant capacity (TEAC), 1,1 diphenyl-2-picryl hydrazyl (DPPH) radicalscavenging activity, as well as reducing power. Kinnow peel extract exhibited the highest reducing power, TEAC, and DPPH free radicalscavenging activity, whereas, the phenolic content of 37.4 mg GAE/g-dw was highest for grape seed extract. Banana peel extract with a low TPC showed the lowest reducing power, TEAC as well as DPPH free radicalscavenging activity among the fruit residue extracts examined in the present study. Correlation analysis between the reducing power and DPPH radicalscavenging ability; reducing power and ABTS radical scavengin...
Oxidative degradation of methylene blue (MB) by Co^2^+-HCO3^- system with H2O2 in aqueous solution was studied. Nearly complete decolorization of the dye was obtained in less than 50min in diluted NaHCO3 solution (25mM) in the presence of only 20mM Co^2^+ ions. Meanwhile, the conjugated structure and phenyl rings of the MB molecule were destroyed or even broken down into small organic acids and inorganic ions, as indicated by FT-IR spectra and ion-chromatography. Photoluminescence probing and radicalscavenging technologies suggested that the reaction of MB degradation in this system mainly involved the generation and participation of hydroxyl radicals. Furthermore, by cyclovoltammetric measurements, the in situ formed different complexes between Co^2^+ and HCO3^- were observed at differen...
BackgroundTrichloroethylene (TCE) may induce oxidative stress which generates free radicals and alters antioxidants or oxygen-free radicalscavenging enzymes.MethodsTwenty...Full Text Available
4-Methylcoumarins that possess two hydroxyl groups ortho to each other in the benzenoid ring have shown to have excellent antioxidant and radical-scavenging properties in different experimental models. Furthermore, they cannot be metabolized by the liver P450 monoxygenases and thus cannot form 3,4-coumarin epoxides, which are believed to be mutagenic. Herein, we present a study on the structure activity relationship of eight synthetic 4-methylcoumarins, carried out by employing a series of different chemical cell-free tests. These compounds were tested by means of three assays involving one redox reaction with the oxidant (DPPH assay, ABTS+ assay and FRAP). Other assays were employed to evaluate the antioxidant properties of the coumarins under investigation against NO, O2- and HClO, which...
The nature of radicals in wood irradiated in vacuum was studied by ESR method. The decay rate of radicals changes in three temperature ranges. Long-lived radicals are very stable at 298"0K, at which the wood-plastics composite has often been studied. The number of radicals formed by irradiations shows fairly good agreement with the total number of radicals in each isolated wood component. The graft copolymerization of MMA to irradiated wood was also studied by means of ESR, and it was found that PMMA propagating radicals are formed in irradiated wood. These radicals are probably formed by the result of graft copolymerization of MMA of wood. (auth.).
A solvent extraction method was developed to obtain methanolic extracts rich in antioxidants from banana peel. Central composite design ''2^3+star'' and response surface methodology were used in order to optimise the number of extraction steps, extraction temperature and extraction time. The number of extractions was statistically the most significant factor in scavenging activity against both DPPH? and ABTS?^+ radicals and in the inhibition of TBARS formation, while the extraction temperature had an important impact on the capacity to prevent b-carotene bleaching. However, the effect of the extraction time on antioxidant activity was less important. The optimum values of the factors that influence the capacity to scavenge DPPH? and ABTS?^+ radicals or to inhibit b-carotene bleaching were ...
Three alternative extraction procedures were carried out in order to separate the antioxidant components and isolate an efficient extract from Origanum dictamnus. Procedure A included sequential extractions with petroleum ether (PE), diethyl ether (DE) and ethanol; procedure B sequential extractions with PE and ethyl acetate (EAc); procedure C a single step extraction with ethanol. The most efficient radicalscavengers, according to the DPPH method, were isolated in ethanol extract of procedure A (mainly rosmarinic acid), followed by ethanol extract of procedure C. However, both ethanol extracts had low solubility in oil and could not protect it. EAc and DE extracts, containing mainly apigenin and epirosmanol ethyl ether, presented lower radicalscavenging activity but were very effective ...
Banana (Musa acuminata Colla AAA) peel extracts obtained in this work had a high capacity to scavenge 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2prime-azino-bis(3-ethylbenzothiazoline)-6-sulfonic acid (ABTS+) free radicals, and they were also good lipid peroxidation inhibitors. Acetone:water extracts were considerably more effective (compared with methanol, ethanol, acetone, water, methanol:water or ethanol:water) at inhibiting the peroxidation of lipids in the b-carotene/linoleic acid system or scavenging free radicals. However, aqueous extracts had a high capacity to protect lipids from oxidation in the thiobarbituric acid reactive substances (TBARS) test, as well as in the b-carotene bleaching assay. In addition, acetone:water most efficiently extracted all extractable components (54+-...
The antioxidant properties of magnolol and honokiol were evaluated in the experimental systems of reducing ONOO^- and ^1O"2, bleaching @b-carotene in linoleic acid (LH) emulsion, and trapping 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonate) cationic radical (ABTS^+?) and 2,2'-diphenyl-1-picrylhydrazyl radical (DPPH), and then were applied to inhibit the oxidation of DNA induced by Cu^2^+/glutathione (GSH) and 2,2'-azobis(2-amidinopropane hydrochloride) (AAPH). Magnolol and honokiol were active to reduce ONOO^- and ^1O"2. Honokiol showed a little higher activity to protect LH and to inhibit Cu^2^+/GSH-induced oxidation of DNA than magnolol. In addition, honokiol exhibited higher activities to trap ABTS^+? and DPPH than magnolol. In particular, honokiol trapped 2.5 radicals while magnolol o...
The OH-initiated photo-oxidation of n-butane was used as a source of 1- and 2-butoxy radicals. Reactions producing ketones and other organic compounds are explained. Rates of photolysis were determined and are discussed.
Using hydrogen at high pressures of up to 150 bar as an OH scavenger in aqueous MV"2"+ solutions (pH 1) it is possible to differentiate between two kinds of transient formed simultaneously by H-atom attack on methyl viologen. One of them is assigned to an H adduct on the N atom, MV"+H"+, with absorption bands identical to those of the radical cation, MV"+. The MV"+H"+ species deprotonates forming the long-lived radical cation, MV"+. The second type of transient produced is attributed to an H-adduct on the ring carbon, MV"2"+H, decaying by second-order kinetics. The formation of MV"+ by electron transfer from the propan-2-ol radical has been reinvestigated (pH 0 to 7); its absorption spectrum does not change in this pH range. Rate constants and molar extinction coefficients are presented. (U.K.).
The purpose was to study the toxicity of drugs known to generate free radicals on isolated pancreatic islets. The accumulattion of "8"6Rb"+ by mouse pancreatic islets was measured in vitro. Exposing the islets to 6-hydroxydopamine, minhydrin, or phenazine methosulphate + NADH inhibited the Rb"+ uptake, whereas paraquat or acetylphenylhydrazine had no effect. This effect of 6-hydroxydopamine was prevented by either of the hydroxyl radicalscavengers, sodium benzoate and mannitol, but not by the non-scavenger,urea; ninhydrin was partially protected against by mannitol but not by benzoate. Protection against 6-hydroxydopamine was also afforded by D-glucose but not by L-glucose or 3-O-methyl-D-glucose; none of the sugars protected against ninhydrin. In damaging islet beta-cells and in being protected against by D-glucose, 6-hydroxydopamine closely resembles the diabetogenic drug, alloxan. It is suggested ...
Experimental investigation data are systematized of free radical states and processes in irradiated proteins. The investigation is performed by the radiospectral methods. Results are discussed in detail of the study of free radicals electronic structure of amino acids, peptides and proteins formed by the action of ionizing radiation. The specificity is stressed of the study of monocrystalls of these compounds by the method of electronic paramagnetic resonance. The nature is also studied of primary centres formed under the effect of radiation on biologically important compounds and their subsequent reactions in solid and liquid solutions. Ion-radical states of different functional groups of the protein molecule are studied. Prospects of the study and the role of anion-radicals in biological processes are discusses.
The efficacy of gamma irradiation as a method of decontamination for food and herbal materials is well established. In the present study, Glycyrrhiza glabra roots were irradiated at doses 5, 10, 15, 20 and 25 kGy in a cobalt-60 irradiator. The irradiated and un-irradiated control samples were evaluated for phenolic contents, antimicrobial activities and DPPH scavenging properties. The result of the present study showed that radiation treatment up to 20 kGy does not affect the antifungal and antibacterial activity of the plant. While sample irradiated at 25 kGy does showed changes in the antibacterial activity against some selected pathogens. No significant differences in the phenolic contents were observed for control and samples irradiated at 5, 10 and 15 kGy radiation doses. However, phenolic contents increased in samples treated with 20 and 25 kGy doses. The DPPH scavenging activity significantly (p<0.05) increased in all irradiated ...
Experiments in a homogeneous charge compression ignition (HCCI) engine have been conducted with four gasoline surrogate fuel blends. The pure components in the surrogate fuels consisted of n-heptane, isooctane, toluene, ethanol and diisobutylene and fuel sensitivities (RON-MON) in the fuel blends ranged from two to nine. The operating conditions for the engine were p{sub in}=0.1 and 0.2 MPa, T{sub in}=80 and 250 C, {phi}=0.25 in air and engine speed 1200 rpm. A semidetailed chemical kinetic model (142 species and 672 reactions) for gasoline surrogate fuels, validated against ignition data from experiments conducted in shock tubes for gasoline surrogate fuel blends at 1.0{<=} p{<=}5.0MPa, 700{<=} T{<=}1200 K and {phi}=1.0, was successfully used to qualitatively predict the HCCI experiments using a single zone modeling approach. The fuel blends that had higher fuel sensitivity were more resistant to autoignition for low intake temperature ...
The mono- and intramolecular cation-radicals (CR) reactions of diethylmercury in the CFCl_3, CFCl_2CF_2Cl matrices and CF_2BrCF_2Br and CFCl_3 freons vitrified mixture (1:1) were studied through the EPR method. Formation of radical products of transformations of the initial CR diethylmercury (X-ray radiation dose - 100-200 Gy at the temperature of 293 K) was studied through the spin trap of 2.4.6 - tri-tret-butylnitrosebenzene.
It was previously reported that the tritium tracer method is useful for the quantitative consideration of hydrogen behavior in coal during coal liquefaction reaction. Tetralin is excellent hydrogen donating solvent, and is considered as one of the model compounds of coal. In this study, effects of H2S and H2O on the hydrogen exchange reaction between tetralin and gaseous hydrogen labeled by tritium were investigated. It was suggested that the conversion of tetralin and the hydrogen exchange reaction between gaseous hydrogen and tetralin proceed through the radicalreaction mechanism with a tetralyl radical as an intermediate product. When H2S existed in this reaction, the hydrogen exchange yield increased drastically without changing the conversion yield. This suggested that the hydrogen exchange reaction proceeds even ...
Pulsed radiolysis method is used to study transformations intermediates of 6-aminophenalenone in ethanol. In alkaline medium the main product is radical-anion of 6-aminophenalenone, which optical absorption spectrum contains two bands with maxima at 355 and 400 nm. The particle precursors are e_s, CH_3CHOH and CH_3CHO"- radicals. In neutral and acid medium radical-anions are protonated in reactions with alcohol and hydrogen ions. The resulting H-adduct of 6-aminophenalenone has optical absorption maxima at 350 and 390 nm. Availability of two maxima is related to two various product structures. Molar extinction coefficients of radical-anions and H-adducts of 6-aminophenalenone and rate constants of reactions with their participation are estimated.
Intermediate products of the conversions of 6-aminophenalenone in ethanol were investigated by pulse radiolysis. In alkaline medium the main product is the 6-aminophenalenone radical cation, the optical absorption spectrum of which contains two bands with maxima at 355 and 400 nm. The precursors of this particle are e_s, CH_3CHOH and CH_3CHO"- radicals. In neutral and acid medium, radical cations are protonated in reactions with alcohol and hydrogen ions. The H-adduct of 6-aminophenalenone that arises has optical absorption maxima at 350 and 390 nm. The presence of two maxima is due to two different structures of the product. The molar extinction coefficients of the radical anions and H-adducts of 6-aminophenalenone and the rate constants of the reactions involving them were estimated. 6 refs., 4 figs., 2 tabs.
The heterogeneous processing of atmospheric aerosols by reaction with nitrogen oxides results in the formation of particulate and adsorbed nitrates. The water content of these hygroscopic nitrate aerosols and consequently the nitrate ion concentration depend on relative humidity, which can impact the physicochemical properties of these aerosols. This report focuses on the 310 nm photolysis of aqueous sodium and calcium nitrate solutions at pH 4 over a wide concentration range of nitrate ion concentrations representative of atmospheric aerosols. In particular, the quantum yield (phi) of nitrite formation was measured and found to significantly decrease at high concentrations of nitrate for Ca(NO(3))(2). In particular, phi for Ca(NO(3))(2) was found to have a maximum value of (7.8 +/- 0.1) x 10(-3) for nitrate ion solution concentrations near one molal, with the smallest quantum yield for the highest concentration solution above 14 m nitrate ion, phi = (2.3 +/- 2.0) ...
The high-energy radiation-induced degradation of an H-acid derivative azo dye, Apollofix-Red SF-28 (AR-28) was studied in aqueous solution by using pulse radiolysis with kinetic spectroscopic detection for transient measurements. Gamma radiolysis with UV-VIS spectroscopy and gradient ionpair HPLC separation with diode array detection were applied for following the destruction of AR-28 and measuring the products. The reactions of hydrated electron (e_a_q "-) and hydroxyl ("#centre dot#OH) radical were investigated separately. "#centre dot#OH reacts with the unsaturated bonds of the molecule. In the further reactions of the "#centre dot#OH adduct radicals, the AR-28 molecules partly reform with a slightly modified structure. The products formed in the first reaction of "#centre dot#OH and AR-28 molecules have also high reactivity towards the "#centre dot#OH ...
The reactions of the hydroxyl radical with hydrocarbons and fluoro hydrocarbons attract significant attention due to their importance in atmospheric chemistry. Its reactions with the two first hydrocarbons, methane and ethane are of special interest because, owing to the small size of these systems, they serve as a prototype for the theoretical studies of hydrogen abstraction reactions. In this work, the reaction and activation energies of the hydroxyl radical abstraction reaction with methane and ethane have been investigated by correlated ab initio and DFT methods. The DFT reaction energies are in good agreement with experimental values, but the activation energies may be in severe error. (authors) 22 refs.
In relation to coal liquefaction reaction, the effect of the coexistence of transferable hydrogen (TH) from process solvent on reduction of radical concentration and the effect of pre-heat treatment on average structure of coals were studied. In experiment, change in radical concentration with temperature rise was measured using the system composed of Yallourn coal and process solvent. The results are as follows. Process solvent with a wide boiling point range of 180-420{degree}C is effective in suppressing an increase in radical concentration even at higher temperature. The effect of hydrogen-donating solvent increases with TH. It was also suggested that high-boiling point constituents in solvent stabilize radicals even over 400{degree}C by vapor phase hydrogenation. The experimental results of pre-heat treatment are as follows. Although the conversion improvement effect of TH is ...
The degradation of irradiated human insulin in aqueous solutions was investigated in order to protect the protein against ionizing radiation. The influence of the drug concentration, excipients and irradiation temperature were studied.Aqueous solutions at pH 2 were irradiated by gamma rays or by accelerated electrons. Two different high-performance liquid chromatography (HPLC) methods were used: reverse-phase high-performance liquid chromatography (RP-HPLC)/UV and size exclusion liquid chromatography (SEC/UV) to investigate both the fragmentation and the formation of higher molecular weight proteins.In solution without excipients irradiated at ambient temperature at 10kGy, the loss of human insulin is almost complete. Addition of radio-protecting excipients (free radicalsscavengers) and c...
ObjectivesTo assess the influence of epigallocatechin-3-gallate (EGCG) on the efficacy of ionizing radiation on prostate cancer cells because of the increased use of dietary interventions, especially by patients with prostate cancer. Radiotherapy is used to treat localized prostate cancer. Some people consume green tea (EGCG) as a chemopreventive agent against prostate cancer. Green tea can act as an antioxidant and induce superoxide dismutase enzymes, which could scavenge the free oxygen radicals generated by radiotherapy. MethodsProstate cancer cell line DU145 cells were treated with EGCG or radiotherapy, or both. Cell death was assessed using trypan blue cell counting, and apoptosis was confirmed by assessing poly (adenosine phosphate ribose) polymerase cleavage. The antioxidant potenti...
The physical and antioxidant properties of alginate biodegradable film incorporating white, red and extruded white ginseng extracts were investigated. No differences in moisture contents of all alginate film samples were noticeable (p>0.05) except those film samples incorporated without ginseng extract, which had the highest moisture content. The addition of ginseng extract to alginate film decreased tensile strength and elastic modulus (p<0.05) but increased the percent elongation at break. The presence of extracts did not significantly affect the water vapor permeability of the film samples. Alginate film containing extruded white ginseng extract at a barrel temperature of 130degreeC presented the highest (61.12%) free-radicalscavenging activity against the 2,2-diphenyl-1-picryhydrazyl ...
Decomposition yields of tetracycline sulphate and oxytetracycline sulphate were determined in argon saturated 0.1N H/sub 2/SO/sub 4/ solutions. The decomposition yields of teracyclines decrease in the presence of the Cl/sup -/ ions. The reaction rate constants of the OH radicals with tetracyclines were also determined.
The aim of present study was to evaluate antioxidant property of Glycyrrhiza glabra root extracts using in vitro models. The dose-dependent aqueous and ethanolic extracts demonstrated the scavenging activity against nitric oxide (concentration that caused 50% inhibition of nitric oxide radicals [IC(50)]=72 and 62.1 microg/ml, respectively), superoxide (IC(50)=64.2 and 38.4 microg/ml, respectively), hydroxyl (IC(50)=81.9 and 63 microg/ml, respectively), DPPH (IC(50)=43.6 and 28.3 microg/ml, respectively) and ABTS(*+) (IC(50)=77.3 and 57.2 microg/ml, respectively) radicals. Further, both extracts showed strong reducing power and iron-chelating capacities. In the Fe(2+)/ascorbate system, both extracts were found to inhibit mitochondrial fraction lipid peroxidation. In copper-catalyzed human serum and low-density lipoprotein oxidation models, both extracts significantly (P<0.05) lengthened the lag phase along with a decline ...
Exposure of albumin to Cu(II) (10-100 microM) and ascorbate (0.1-2 mM) results in extensive molecular modifications, indicated by decreased fluorescence and chain breaks. The rate of utilization of...Full Text Available
The dissociation of methylal is investigated using mass spectrometry, combined with a pyrolytic radical source and femtosecond pump probe experiments. Based on preliminary results two reaction paths of methylal dissociation are proposed and discussed. (author) 4 fig., 3 refs.
The development of detailed chemical kinetic reaction mechanisms for oxidation of n-octane and iso-octane is described, with emphasis on the factors which are specific to many large hydrocarbon fuel molecules. Elements which are of particular importance are found to include site-specific abstraction of H atoms, radical isomerization of alkyl radicals by internal H atom abstraction, and rapid ..beta..-scission of the alkyl radicals. These features, combined with distinctions in the types of intermediate olefin species produced, are used to explain the significant differences in the rate of oxidation between n-octane and iso-octane. Experimental results from the turbulent flow reactor and low pressure laminar flames, using both n-octane and iso-octane as fuels, are used to test the reaction mechanisms and indicate those parts of the total mechanisms which are in greatest need of ...
Detailed chemical kinetic reaction mechanisms are developed for combustion of all nine isomers of heptane (C{sub 7}H{sub 16}), and these mechanisms are tested by simulating autoignition of each isomer under rapid compression machine conditions. The reaction mechanisms focus on the manner in which the molecular structure of each isomer determines the rates and product distributions of possible classes of reactions. The reaction pathways emphasize the importance of alkylperoxy radical isomerizations and addition reactions of molecular oxygen to alkyl and hydroperoxyalkyl radicals. A new reaction group has been added to past models, in which hydroperoxyalkyl radicals that originated with abstraction of an H atom from a tertiary site in the parent heptane molecule are assigned new ...
For better understanding and proper use of organic chemicals addition data are needed, including kinetic data on the scavengingreactions in actual cycles, data on ambient temperature stability and decomposition, sampling and analsyis information, data on effects in a case of fire, and more corrosion data. Use of these chemicals for layup of boilers and other equipment needs to be evaluated for each application. After a preliminary evaluation, such as outlined in this report, every new water treatment chemical should be evaluated in at least two month test in actual steam cycle. (orig.).
Insect host/parasitoid interactions are co-evolved systems in which host defenses are balanced by parasitoid mechanisms to disable or hide from host immune effectors. Although there is a rich literature on these systems, parasitoid immune-disabling mechanisms have not been fully elucidated. Here we report on a newly discovered immune-disabling mechanism in the Pieris rapae/Pteromalus puparum host/parasitoid system. Because venom injections and parasitization suppresses host phagocytosis, we turned attention to the P. rapae scavenger receptor (Pr-SR), posing the hypothesis that P. puparum venom suppresses expression of the host Pr-SR gene. To test our hypothesis, we cloned a full-length cDNA of the Pr-SR. Multiple sequences alignment showed the deduced amino acid sequence of Pr-SR is similar to scavenger receptors of other lepidopterans. Bacterial and bead injections induced Pr-SR mRNA and protein expression, which peaked at 4h post-bead ...
Microgel-clay composite particles were prepared by one-step surfactant-free precipitation polymerization. Laponite nanoparticles present in the reaction mixture become encapsulated during the microgel formation process. Microgel-clay composites based on poly(N-vinylcaprolactam-co-acetoacetoxyethyl methacrylate) containing different amount of incorporated clay nanoparticles were synthesized. The clay content was varied from 2 wt% to 18 wt%. The extremely high incorporation efficiency of the clay nanoparticles into microgels was detected. The size of the hybrid microgels was decreased from 700 nm to 100 nm by increase of the clay concentration in the reaction mixture. Obtained hybrid microgels exhibit negative surface charge and excellent colloidal stability. Microgel-clay composite particle...
Pulse radiolysis studies of the formation kinetics and the yields of various phenylcarbenium ions from several different solutes in 1,2-dichloroethane solution have been carried out. The results indicate that there are two kinetically distinguishable cationic species of the solvent which react selectively with the different solutes to form the phenylcarbenium ions. It is suggested that one is a cation radical (yield 0.68 molecule/100 eV) and the other a carbocation (yield 0.20 molecule/100 eV). Rate constants for their separate reactions with selected aromatic compounds and with ammonia have been determined. Molar extinction coefficients have been estimated for benzyl cation, diphenyl cation radical, and anthracene cation radical. 6 figures, 1 table.
Pulse radiolysis studies of the formation kinetics and the yields of various phenylcarbenium ions from several different solutes in 1,2-dichloroethane solution have been carried out. The results indicate that there are two kinetically distinguishable cationic species of the solvent which react selectively with the different solutes to form the phenylcarbenium ions. It is suggested that one is a cation radical (yield 0.68 molecule/100 eV) and the other a carbocation (yield 0.20 molecule/100 eV). Rate constants for their separate reactions with selected aromatic compounds and with ammonia have been determined. Molar extinction coefficients have been estimated for benzyl cation, diphenyl cation radical, and anthracene cation radical. 6 figures, 1 table.
Summary The antioxidant properties and toxicity profile of roasted noni (Morinda citrifolia L.) leaf infusion were evaluated. The 2,2-diphenylpicrylhydrazyl (DPPH) radicalscavenging activity was greater than green tea infusion (81.6 +- 0.9% vs. 57.5 +- 1.8%, P < 0.001). The mean quercetin and kaempferol contents of roasted noni leaf infusion, as prepared by the consumer, were 0.24 +- 0.01 and 0.14 +- 0.01 mg mL-1, respectively. Tannic acid content was 10 +- 1 mg mL-1. The infusion was non-mutagenic in the reverse mutation test in Salmonella typhimurium and did not induce primary DNA damage in E. coli PQ37. Further, no significant primary DNA damage was induced by 5,15-dimethylmorindol, which was the only detectable anthraquinone in noni leaves. The infusion was not cytotoxic in the 24 h b...
Pulse radiolysis has been used to optically and kinetically characterize the transient free radicals formed by the reaction of H"s"m"-"b"u"l"l"e"t, N_3"s"m"-"b"u"l"l"e"t, or OH"s"m"-"b"u"l"l"e"t with 2,4,5-trichlorophenol (TCP-OH). The hydroxy-2,4,5-trichlorocyclohexadienyl radical (H-TCP-OH) formed by H"s"m"-"b"u"l"l"e"t addition to TCP-OH [k = (1.1 #+-# 0.2) x 10"9 M"-"1 s"-"1] has an absorption maximum at 360 nm with #epsilon#_3_6_0 = (4700 #+-# 1000) M"-"1 cm"-"1. The 2,4,5-trichlorophenoxyl radical (TCP-O"s"m"-"b"u"l"l"e"t) formed by the reaction of N_3"s"m"-"b"u"l"l"e"t with TCP-O- [k = (4.3 #+-# 0.8) x 10"9 M"-"1 s"-"1] has an absorption maximum at 430 nm with #epsilon#_4_3_0 = (3600 #+-# 600) M"-"1 cm"-"1. The dihydroxy-2,4,5-trichlorocyclohexadienyl radical (HO-TCP-OH) formed by OH"s"m"-"b"u"l"l"e"t radical addition to TCP-OH [k = ...
Hydroperoxides are important atmospheric oxidants. They are responsible for most of the oxidation of aqueous-phase SO(sub 2) to sulfate in the northeastern United States, resulting in the formation of acid precipitation and visibility-reducing sulfate aerosol (Penkett et al., 1979; Lind et al., 1987; Madronich and Calvert, 1990; Tanner and Schorran, 1995). Atmospheric hydrogen peroxide (H(sub 2)O(sub 2) or HP) is produced by the self-reaction of hydroperoxyl radicals (HO(sub 2)); higher organic peroxides are produced by reaction of HO(sub 2) with alkylperoxyl radicals (RO(sub 2)). Peroxyl radicals, along with OH, are chain carriers in the complex photochemical process that produces tropospheric ozone. Thus, concentrations of peroxides and their free radical precursors depend on solar intensity and ambient concentrations of water vapor, ozone, NO(sub x) (NO+ ...
Aqueous deoxyhemoglobin solutions (2 mg/ml) were gamma-irradiated by a "6"0Co source in the presence of methanol, ethanol, 1-butanol and t-butanol under N_2O or argon. The effects of the interaction of the particular alcohol radical species with hemoglobin were determined according to the detected spectral alterations in the visible range. The amounts of stable final products in the form of methemoglobin (MetHb) and the sum of hemichromes and cholehemichromes (Hemichr) were estimated in irradiated preparations. For preparations irradiated under N_2O, the radiation yield for MetHb formation was three-fold lower in the presence of ethanol and 1-butanol [G(MetHb) = 0.33[ compared with preparations irradiated in the presence of t-butanol or without alcohol [G(MetHb) = 1.00[. The yield of hemichromes and cholehemichromes in preparations irradiated under N_2O increased in the order: ethanol (G = 0.38), 1-butanol (B = 0.52), t-butanol (G = 0.59), and in the absence of ...
The gas-phase reaction of benzene with O(3P) is of considerable interest for modeling of aromatic oxidation, and also because there exist fundamental questions concerning the prominence of intersystem crossing in the reaction. While its overall rate constant has been studied extensively, there are still significant uncertainties in the product distribution. The reaction proceeds mainly through the addition of the O atom to benzene, forming an initial triplet diradical adduct, which can either dissociate to form the phenoxy radical and H atom, or undergo intersystem crossing onto a singlet surface, followed by a multiplicity of internal isomerizations, leading to several possible reaction products. In this work, we examined the product branching ratios of the reaction between benzene and O(3P) over the temperature range of 300 to 1000 K and pressure range of 1 to ...
The radiation induced reactions in LDPE in the presence of phenolic type antioxidants have been studied. It was shown that various antioxidants can influence the polyethylene network formation and the radical yield in different ways. The dependence of network structure on absorbed doses was determined by gel analysis, hot-set test and extraction of antioxidants for samples irradiated with accelerated electrons. It was found that the antioxidants eluted from polyethylene in higher percentage influence polymer crosslinking to a smaller degree. The ESR studies of #gamma#-irradiated blends of polyethylene with antioxidant indicate the presence of alkyl and phenoxyl radicals. The role of antioxidant molecules on radiation induced reactions in polyethylene-antioxidant systems is considered. The correlation between the network structure and the type of additive in polyethylene is also discussed. (author).
It is well established from experiments in premixed, laminar flames, jet-stirred reactors, flow reactors, and batch reactors that SO2 acts to catalyze hydrogen atom removal at stoichiometric and reducing conditions. However, the commonly accepted mechanism for radical removal, SO2 + H(+M) reversible arrow HOSO(+M), HOSO + H/OH reversible arrow SO2 + H-2/H2O, has been challenged by recent theoretical and experimental results. Based on ab initio calculations for key reactions, we update the kinetic model for this chemistry and re-examine the mechanism of fuel/SO2 interactions. We find that the interaction of SO, with the radical pool is more complex than previously assumed, involving HOSO and SO, as well as, at high temperatures also HSO, SH, and S. The revised mechanism with a high rate constant for H + SO2 recombination and with SO + H2O, rather than SO2 + H-2, as major products of the HOSO + H reaction ...
The purpose of work is systematical studying of benzo (B) of thiophene-1,1-dioxides and their 2,3-di-hydro derivatives behaviour in the reactions of electrophflic, radical, nucleophilic nitration, reduction of nitro group, embodiment of synthesis of N-amino derivatives, investigation of sulfur containing hetero-cyclic compounds, including of residues of some steroids
Abstract A diacrylate polysulfone oligomer is synthesized and used as the acrylic oligomer for the in situ synthesis of noble metal/PSU nanocomposites through UV-induced simultaneous radical polymerization of acrylic functionalities and NP formation by reduction of their precursors. Thus, silver or gold NPs are formed in situ during polymer network formation. FESEM analysis of the morphology of the cured systems demonstrates that the nanoparticles of the noble metals are homogeneously distributed in the network without macroscopic agglomeration.
A number of amines can be employed for all volatile treatment (AVT) of steam generator (SG) systems of nuclear power reactors. These amines form complexes with Cu{sup 2+} and Ni{sup 2+} ions which come into water due to corrosion. The redox reactions of a number of Cu(II)-AVT amine complexes and the stability of the transient species formed have been studied by pulse radiolysis technique. Rate constants for the reaction of e{sub aq}{sup -} with a number of Cu(II)-amine complexes have been determined by following the decay of e{sub aq}{sup -} absorption. Stability of Cu(I)-amine complexes was studied by following the kinetics of the bleaching signal formed at the {lambda}{sub max} of the Cu(II) amine complex. Except for Cu(I)-triethanolamine complex all other Cu(I)-amine complexes were found to be stable. One-electron oxidation of Cu(II) amine complexes was studied using azidyl radicals for the oxidation ...
The reactions of CF{sub 3}O radicals with (1) NO and (2) NO{sub 2} were studied using two different experimental techniques. A laser photolysis/LIF detection method was applied for measuring the rate constants as a function of temperature (T=222-302 K) and total pressure (p{sub tot}=7-107 mbar). Whereas the reaction with (1) NO was found to be independent of temperature and pressure with k{sub 1}=(4.5{+-}1.2) x 10{sup -11} cm{sup 3}s{sup -1}, the reaction with (2) NO{sub 2} was found to be dependent on both of these variables. The temperature dependence of k{sub 2} in the high pressure limit can be given by the expression k{sub 2{infinity}}{sup -}(T)=(8{+-}5) x 10{sup -13} exp ((863{+-}194) K/T) cm{sup 3}s{sup -1}. The product distributions of the two reactions were determined in separate experiments using steady-state photolysis combined with FTIR spectroscopy. For ...
Observational evidence is presented for the nucleation of condensation nuclei (CN) in the clear air adjacent to an isolated, marine, cumulus cloud. Two separate regions of particle nucleation are identified: one located above the cloud top, and the second located downwind of the cloud near the level of the anvil outflow. The regions of high CN concentrations were located in extremely clean marine air, with unactivated aerosol surface area (excluding the nucleation mode) less than 2 sq micrometers/cu cm, air temperature -31 C, and higher relative humidities than the undisturbed environment. Vertical profile measurements downwind of the cloud showed that CN concentrations at the level of the anvil outflow (4.9 km) were 8 times greater than at any other level between the surface and 5.3 km. A conceptual model is formulated in which aerosol particles, sulfur dioxide (SO2), sulfuric acid vapor (H2SO4), dimethyl sulfide (DMS), and ozone (O3) from the boundary layer are entrained into the ...
One-electron oxidation of several derivatives of pyrazolin-5-one, including the drug antipyrine, were studied by pulse radiolysis of aqueous solutions. All the compounds were found to be oxidized by Br2 rapidly but considerably more slowly by weaker oxidants, such as peroxyl radicals. From redox equilibria using p-methoxyphenol and N,N,N',N'-tetramethyl-p-phenylenediamine as reference compounds, the one-electron oxidation potentials of the methyl-substituted 2-pyrazolin-5-ones were found to be in the range of 0.32-0.39 V versus normal hydrogen electrode. The relevance of these findings to the properties of the drug nafazatrom is discussed. Antipyrine was found to have a much higher oxidation potential, estimated as 1.2-1.5 V, which is rationalized on the basis of the phenyl substitution and lack of resonance stabilization of the radical cation.
Here we report a new method for measuring the heterogeneous chemistry of submicron organic aerosol particles using a continuous flow stirred tank reactor. This approach is designed to quantify the real time heterogeneous kinetics, using a relative rate method, under conditions of low oxidant concentration and long reaction times that more closely mimic the real atmosphere. A general analytical expression, which couples the aerosol chemistry with the flow dynamics in the chamber is developed and applied to the heterogeneous oxidation of squalane particles by hydroxyl radicals (OH) in the presence of O2. The particle phase reaction is monitored via photoionization aerosol mass spectrometry and yields a reactive uptake coefficient of 0.51+-0.10, using OH concentrations of 1-7x108 molec cdot cm-3 and reaction times of 1.5+-3 hours. This uptake coefficient is larger than that found for the ...
Lysozyme dimers produced on oxidation of lysozyme with Br_2anion radicals in aqueous solutions exhibit a fluorescence spectrum (lambdasub(max) = 400 nm) closely similar to that of bi-tyrosine. This suggests that the dimer is likely to have a tyrosine-tyrosine bond resulting from the combination of tyrosine phenoxy radicals of two lysozyme molecules. Kinetic studies on dimer formation were made by measuring time-dependent fluorescence after pulsed-electron irradiation over wide pH range. The results lead to the following conclusions. The second-order growth of the dimer fluorescence observed at pH 10.7-12.5 reflects the combination process of the lysozyme radicals, which is rate-determining in the pH range. On the other hand, the first-order growth observed at pH 6.8-10.2 is attributable to the enolization of the keto-form of the dimer. A tentative reaction scheme is proposed for the dimer formation. ...
The proposed active sites on the catalyst surface in heterogeneous propylene ammoxidation have been successfully modelled by structurally characterized pinacolato W(VI) tert-butylimido complexes. These compounds exist as an equilibrating mixture of amine-bis(imido) and imido-bis(amido) complexes, the position of this equilibrium is dependent on the electronic nature of the glycolate ligand. Both of the C-N bond-forming reactions proposed in recent studies by Grasselli et al. (1) have been reproduced using discrete Group VI d{sup 0} organoimido complexes under mild conditions suitable for detailed mechanistic studies. These reactions are: (1) oxidative trapping of radicals at molybdenum imido sites, and (2) migration of the allyl group from oxygen to an imido nitrogen atom.
In this thesis the rate constants for a number of radicalreactions in aqueous solution have been studied in a wide temperature range. The reactions of H with H_2O_2, OH and HO_2 and the reactions of HO_2 with OH, Fe"2"+ and Cu"2"+ have been studied. For each reaction rate constants have been determined as a function of temperature using the technique of high temperature, high pressure (HTP) pulse radiolysis. The rate constants were obtained by fitting a kinetic computer model to the experimental data. From an Arrhenius plot the activation energy of each reaction was determined. The data determined in this way are important for modeling of radiolysis in nuclear light water reactors. A previously developed model for calculation of the effect of water radiolysis products on oxidation and dissolution of spent nuclear fuel has been improved. In the new model, called ...
In order to develop modern two-stroke engines with low fuel consumption, respectively with low exhaust emissions, two alternative development areas -- the mixture formation and the scavenging system -- have been correlated. For a satisfying mixture formation without fuel losses by scavenging, the direct injection seems to be one of the best solution for the high speed two-stroke engine of the future. On the other hand the modern development of two-stroke scavenging systems shows a large field of application and improvement methods of cross and loop scavenging. Based on the specific optimization factors of the injection system, respectively of the scavenging system, the aim off this common work of the Universities of Pisa and Zwickau is to correlate both the optimization fields in an advantageous mixture formation process. The principal elements of this correlation are the design of ...
Nitrite was measured in atmospheric liquid phase samples between 1998 and 2005 to investigate the heterogeneous formation of nitrous acid in the lower atmosphere, as well as to assess the quality of water recovered from dew. The samples were collected during ground-based cloud field experiments at different German mountain sites (Brocken, Schmucke, and Hohenpeissenberg) and at a site south of the Bordeaux urban area (France). Concentrations found in Bordeaux dew samples (up to 2800 ?gl-1) are comparable to those found elsewhere in urban fog and dew water and considerably higher than those detected in cloud water or rain. Particulate nitrite (and nitrate) as well as HNO2 (HNO3) data in air masses from a foothill site of Mt. Schmucke, before involved in cloud processing, are also presented. In clouds at Mt. Brocken, both the interstitial HNO2 gas and the aqueous phase nitrite concentration have been measured simultaneous. Significant deviations from Henry's law have been observed, ...
Numerous studies have investigated degradation of individual endocrine disrupting compounds (EDCs) in lab or natural waters. However, natural variations in water matrices and mixtures of EDCs in the environment may confound analysis of the treatment efficiency. Because chemical based analytical methods cannot represent the combined or synergistic activities between water quality parameters and/or the EDC mixtures at environmentally relevant concentrations ({mu}g L{sup -1}-ng L{sup -1}), bioanalytical assessments of residual estrogenic activity in treated water were used to evaluate the performance of the UV based advanced oxidation process for estrogenic contaminants in water. Four EDCs including estradiol (E{sub 2}), ethinyl estradiol (EE{sub 2}), bisphenol-A (BPA) and nonylphenol (NP) were spiked individually or as a mixture at {mu}g L{sup -1}-ng L{sup -1} in laboratory or natural river water. The removal rates of estrogenic activity were quantitatively evaluated by in vitro yeast ...
Since antioxidants have been shown to play a major role in preventing some of the effects of aging and photoaging in skin, it is important to study this phenomenon in a controlled manner. This was accomplished by developing a simple and reliable in vitro technique to assay antioxidant efficacy. Inhibition of peroxidation by antioxidants was used as a measure of relative antioxidant potential. Liposomes, high in polyunsaturated fatty acids (PUFA), were dispersed in buffer and irradiated with ultraviolet (UV) light. Irradiated liposomes exhibited a significantly higher amount of hydroperoxides than liposomes containing antioxidants in a dose- and concentration-dependent manner. Lipid peroxidation was determined spectrophotometrically by an increase in thiobarbituric acid reacting substances. To further substantiate the production of lipid peroxides, gas chromatography was used to measure a decrease in PUFA substrate. In order of decreasing antioxidant effectiveness, the following results ...
We present a systematic analysis of backward pion photoproduction for the reactions {gamma}p{yields}{pi}{sup 0}p and {gamma}p{yields}{pi}{sup +}n. Regge phenomenology is applied at invariant collision energies above 3GeV in order to fix the reaction amplitude. A comparision with older data on {pi}{sup 0}- and {pi}{sup +}-photoproduction at {theta}=180 indicates that the high-energy limit as given by the Regge calculation could be reached possibly at energies of around {radical}(s){approx_equal}3 GeV. In the energy region of {radical}(s){<=}2.5 GeV, covered by the new measurements of {gamma}p{yields}{pi}{sup 0} p differential cross-sections at large angles at ELSA, JLab, and LEPS, we see no clear signal for a convergence towards the Regge results. The baryon trajectories obtained in our analysis are in good agreement with those given by the spectrum of excited baryons. (orig.)
Decomposition yields of tetracycline hydrochloride (TC.HCl) and chlorotetracycline hydrochloride (ClTC.HCl) in methanol solution saturated with Ar or N/sub 2/O were determined. Rate constants of the reaction esub(s)/sup -/ with some antibiotics were obtained. It was demonstrated by /sup 1/H NMR that the radical formed by degradation of 7-C-Cl group is recombined with the H atoms leading to ClTC.HCl being converted into tetracycline hydrochloride (TC.HCl).
In this paper, bond cleavage reactions are discussed in relation to the softening and solubilization of coal. Were used 9,10-dihydroanthracene (DHA) and 9,10-dihydrophenanthrene (DHP) as models of hydrogen donating compounds in coal, and bibenzyl, 1,2-diethane, benzylphenylether, and 1,5-dibenzylnaphthalene were used as models of bridge structure compounds. They were compared mutually, as to reactivity of coal against DHA and DHP. For the homolytic cleavage of bridges, DHA with excellent radical supplement performance provided excellent hydrogen donating performance. While, for the ipso-position cleavage of bridges, it was found that DHP can act as an effective hydrogen donor. For the reaction between coal and hydrogenated aromatic compounds, cleavage of relatively weak bonds, such as ether linkage and dimethylene linkage, occurred at about 380{degree}C, and hydrogen from DHA or DHP was consumed. On the other hand, the ...
Comprehensive investigation has been made into the application of the polymerization hardening by radiation, particularly electron beam, to the composites of polymers and other materials. The report is divided into four parts, namely 1) characteristics and problems of the reaction of curing by radiation polymerization, 2) improvement of the bonding capability of high molecular weight materials, 3) bonding by radiation, and 4) composites made by the impregnation and polymerization hardening of monomers. The first part includes the effects of dose rate, temperature rise during the hardening, the peculiarity of electron beam irradiation at high dose rate, reaction environment and additive effects. Main conclusions are as follows: caution must be taken to the amount of residual double bonds because they affect the quality of hardened polymers; the polymerization hardening reaction at high dose rate cannot be analogized by that ...
The atmospheric chemical behaviour of 2H-Heptafluoropropane (CF[sub 3]CHFCF[sub 3], HFC-227) with respect to its rate and mechanism of degradation in the troposphere has been investigated. The rate coefficient for the reaction of HFC-227 with OH radicals has been determined in direct time resolved experiments using a combination of laser-pulse initiation and LIF. In the temperature range T=298-463 K the Arrhenius expression k(T)=(3.8[+-]0.8) 10[sup -13] exp(-1596[+-]77 K/T) cm[sup 3]/s, which corresponds to k (298 K) = (1.8[+-]0.3) 10[sup -15] cm[sup 3]/s, was found. The mechanism of the atmospheric degradation of HFC-227 has been investigated using both, laser-pulse initiated/time resolved and UV photolysis/FTIR product studies. It is concluded that the major carbonyl products are CF[sub 3]COF and CF[sub 2]O which result from the decomposition of the oxy radical CF[sub 3]CF(O)CF[sub 3] by C-C bound fission. The rate ...
The reactions of tetraphenylphosphonium ion (Ar_4P"+) with esub(aq)"-, H atoms and OH radicals have been investigated. The absorption spectra of three transient species were obtained. Ar_4Psup(.) radicals formed by the reaction: Ar_4P"+ + esub(aq)"- #-># Ar_4Psup(.) have a maximum absorption at 305 nm [epsilon _3_0_5 = (9400 +- 300)dm"3mol"-"1cm"-"1] and decays by second-order kinetics with the rate constant 2k = (2.7 +- 0.4) x 10"9dm"3mol"-"1s"-"1. H atoms and OH radicals form transient adducts to the phenyl groups of the Ar_4P"+ ion with the rate constants of (1.5 +- 0.3) x 10"9 dm"3mol"-"1s"-"1 and (3.0 +- 0.3) x 10"9dm"3mol"-"1s"-"1, respectively. Both adducts have broad absorption spectra at 300 approximately 380 nm (lambdasub(max) = 340 nm) with the molar extinction coefficients epsilonsub(340) = 5400 +- 300 dm"3mol"-"1cm"-"1 for the H adduct and epsilonsub(340) = 3500 +- ...
Microsecond pulse radiolysis of oxygenated aqueous solutions containing 0.02 mol dm"-"3 sodium formate and 2 mmol dm"-"3 phosphate buffer at pH 7 was used to generate superoxide anion radicals. The influence of some biologically important compounds upon the rate of O_2"."-"b"a"r decay as monitored spectrophotometrically in the range of 245-300 nm. Hematoporphyrin (HP), hemin C (HC), catalase (Cat), cobalt sulfophthalocyanine (CoTSPc) were studied. Among the investigated compounds only Cat was found to show a high catalytic efficiency towards the self-decay of O_2"."-"b"a"r. A red shift of 0_2"."-"b"a"r absorption band and slowing down of its decay were observed to take place by adding HP or CoTSPc to the solutions containing formate ions in excess. This effect is associated with the formation of a transient superoxo-complex. An appearance of an intermediate species with absorption maxima at 350 nm and half-life of about 2 s was observed to accompany the ...
For the coal liquefaction, improvement of liquefaction conditions and increase of liquefied oil yield are expected by suppressing the recombination through rapid stabilization of pyrolytic radicals which are formed at the initial stage of liquefaction. Two-stage liquefaction combining prethermal treatment and liquefaction was performed under various conditions, to investigate the effects of reaction conditions on the yields and properties of products as well as to increase liquefied oil yield. Consequently, it was found that the catalyst contributes greatly to the hydrogen transfer to coal at the prethermal treatment. High yield of n-hexane soluble fraction with products having low condensation degree could be obtained by combining the prethermal treatment in the presence of hydrogen and catalyst with the concentration of slurry after the treatment. This was considered to be caused by the synergetic effect between the improvement of ...
The transients involved in the reaction of tetracycline (TC) with reducing radicals such as e{sub aq}{sup -}, (CH{sub 3}){sub 2}COH and CO{sub 2}{sup .-}have been characterized by the pulse radiolysis technique. The semi-reduced species formed ({lambda}{sub max} = 630 nm, {epsilon} 3.4 x 10{sup 3} dm{sup 3} mol{sup -1} cm{sup -1}) has been found to be a strong reductant with reduction potential lying in the range -0.450 to -1.40 V vs NHE. TC reacts with e{sub aq}{sup -} at diffusion-controlled rates and the rate constant, depending upon the ionic form of TC existing at a particular pH, varies from 1.2 x 10{sup 10} to 2.8 x 10{sup 10} dm{sup 3} mol{sup -1} s{sup -1}. Based on these results a plausible site of electron addition has been suggested. Reaction of H atoms with TC gives rise to a transient which exhibits spectral and kinetic features different from that of semi-reduced species. (author).
The phenomenology of wire chamber aging is discussed and fundamentals of proportional counters are presented. Free-radical polymerization and plasma polymerization are discussed. The chemistry of wire aging is reviewed. Similarities between wire chamber plasma (>1 atm dc-discharge) and low-pressure rf-discharge plasmas, which have been more widely studied, are suggested. Construction and use of a system to allow study of the plasma reactions occurring in wire chambers is reported. A proportional tube irradiated by an {sup 55}Fe source is used as a model wire chamber. Condensable species in the proportional tube effluent are concentrated in a cryotrap and analyzed by gas chromatography/mass spectrometry. Several different wire chamber gases (methane, argon/methane, ethane, argon/ethane, propane, argon/isobutane) are tested and their reaction products qualitatively identified. For all gases tested except those containing ...
Graft copolymerization of sodium styrene sulfonate (SSS) onto electron beam (EB) irradiated poly(vinylidene fluoride) (PVDF) films was investigated to find out a simple preparation process for sulfonic acid proton exchange membranes with respect to monomer concentration, absorbed dose, temperature, film thickness and storage time. The reaction order of the monomer concentration and absorbed dose of grafting was found to be 2.84 and 1.20, respectively. The overall activation energy for graft copolymerization reaction was calculated to be 11.36 kJ/mol. The initial rate of grafting was found to decrease with an increase in the film thickness. The trapped radicals in the irradiated PVDF films remained effective in initiating the reaction without considerable loss in grafting level up to 180 days, when stored under -60 {sup o}C. The presence and distribution of polystyrene sulfonate grafts in the obtained ...
Gamma-irradiation of isolated rat liver mitochondria with up to 475 Gy leading to hydrated electrons (G = 1.9, corrected for reaction with solutes), 30 Gy leading to carbohydrate radicals, (G = 5.6), 100 Gy leading to superoxide radicals (G = 6.2), and 130 Gy leading to formate radicals (G = 6.2) showed no effects on the rate of oxygen uptake in various respiratory states, the respiratory control ratio, or the adenosine diphosphate to atomic oxygen ratio. Typical values were 0.020-0.100 nmol O/sub 2/ s/sup -1/ mg protein/sup -1/ for State 1 respiration, 0.25-0.33 nmol O/sub 2/ s/sup -1/ mg protein/sup -1/ for State 4 respiration and 0.65-1.10 nmol O/sub 2/ s/sup -1/ mg protein/sup -1/ for State 3 respiration. Typical respiratory control ratios ranged from 2.0-3.5 for succinate and 4.0-6.5 for a 1:1 glutamate: malate substrate mixture. Adenosine diphosphate to atomic oxygen ratios with succinate as ...
The primary charge separation in photosynthetic bacteria generates a dimeric bacteriochlorophyll (BChl) cation and a bacteriopheophytin (BPheo) anion which lie within close proximity of each other (approx. 10 A). The two radicals also lie within van der Waals contact on opposite sides of a lone BChl bridging molecule. Spectral changes in the red (Q/sub y/) band of the bridge BChls have been observed on picosecond time scales following excitation of the reaction center (RC) and have been variously attributed to the formation of a BChl anion, to a charge-transfer state, or to electrochromic effects. They present calculations here which suggest that electrochromic effects caused by the photogenerated cation and/or anion can rationalize the optical changes observed in the flash photolyses as well as in trapping experiments.
During this report period, we have obtained a model of montmorillonite clay, and this model has been of great assistance in visualizing how the chemistry of substrate molecules might be altered as it occurs on the surface of the clay. A stereochemical representation of this montmorillonite model is shown. Of particular significance, this model indicates that hydroxyl groups are located in the center of each siloxane ring on the surface of the montmorillonite clay. These hydroxyl groups might serve to bond substrate molecules to the surface of the clay. The next step in our systematic examination of the radical cation-initiated dimerization of plant monomers from the C{sub 6}-C{sub 3} pool of shikimic acid metabolites was to study the dimerization of cinnamic acid and its derivatives. In the next block of research, we examined the reaction of montmorillonite clay (K-10) with methyleugenol. 2 refs.
Recent data on {eta} -meson photoproduction off a proton target in the energy range 2 {<=}{radical}(s){<=} 3 GeV are analyzed with regard to their overall consistency. Results from the ELSA and CLAS measurements are compared with predictions of a Regge model whose reaction amplitude was fixed via a global fit to pre-2000 measurements of differential cross sections and polarization observables for {gamma}p{yields}{eta}p at higher energies. We find that all recent experimental results on differential cross sections for {eta} -meson photoproduction are in good agreement with each other, except for the CLAS data from 2009. However, the latter can be made consistent with the other data at the expense of introducing an energy-dependent renormalization factor. We point out that there are indications in the data for a possible excitation of baryon resonances with masses around 2.1 and 2.4GeV. (orig.)
A vast amount of circumstantial evidence implicates oxygen-derived free radicals (especially, superoxide and hydroxyl radical) and high-energy oxidants [such as peroxynitrite (OONO−)]...Full Text Available
Comparisons have been made between Buddhism and the philosophy of science in general, but there have been only a few attempts to draw comparisons directly with the philosophy of radical behaviorism....Full Text Available
The authors present some recent measurements on electroweak physics using data collected by the CDF experiment at the Tevatron proton anti-proton collider ({radical}s = 1.96 TeV) at Fermilab.
The aim of the study is to prepare ionic exchangers using the polymerization of unsaturated polyster with monomeric styrene units in a ratio of 60%: 40% respectively. The type of method involved in this preparation, is called An Emulsion Polymerization. Such type of polymerization was carried out by two techniques: chemical and irradiation techniques. The first techniques requires the formation of free radical monomers by use of methyl Ethy Ketone Peroxide capable of decomposing into free radicals upon heating, while the other technique involves the use of gamma rays (using Co-60 source) capable of activating monomers towards free radical formations. A number of very effective chemical parameters and physical factors were used and investigated throughout the reactions such as: dispersant matrix, viscosity, rate of mixing, and irradiation dose. Besides, the study has included the study of the rate of ...
The work presented here demonstrates the ability of proton-transfer-reaction mass spectrometry (PTR-MS) to perform fast-response measurements of volatile organic compounds (VOCs) (including methanol, acetonitrile, acetaldehyde, acetone, PAN-type compounds, alpha- and beta-pinene, nopinone and pinonaldehyde) at the pptv level and its versatile applicability in the field of environmental trace gas analysis. Laboratory and field experiments including various calibration techniques and intercomparisons with other measurement techniques such as gas chromatography, atmospheric pressure chemical ionization and Fourier transformation infrared spectroscopy were performed providing a first characterization of the PTR-MS instrument performance (sensitivity, detection limit, precision, accuracy). Typically a detection limit (S/N=2) of 50 pptv for a 10 s signal integration time, a precision of 5 % and an accuracy in the range between 10 and 25 % were observed. Due to its ...
Color formation in aqueous solutions of the ditetrazolium salt blue tetrazolium (BT{sup 2+}) in the absence or presence of oxygen is a complex radiation chemical reaction. The final stable product is the poorly soluble diformazan violet to blue pigment having a broad spectral absorption band ({lambda}{sub max}=552 nm). The reaction of BT{sup 2+} with the hydrated electron proceeds by rapid reduction of BT{sup 2+} followed by protonation at the nitrogen closest to the unsubstituted phenyl group, via the two intermediate tetrazolinyl radicals shared by the ditetrazole ring nitrogens. The effect of solution pH, N{sub 2}O saturation, and the presence of the reducing agent dextrose are examined. The system serves as a radiochromic sensor and a dosimeter of ionizing radiations. Solutions of 5 mmol l{sup -1} BT{sup 2+} at pH 7.3 serve as dosimeters over an absorbed-dose range of approximately 0.2-6 kGy (dearated, with a range of ...
The manufacture and use of wood/plastic composite (WPC) as an example of wood matrix and wood sawdust/plastic composites (SDP) as an example of plastic matrix are reviewed. The raw material for WPC are mostly vinyl monomers, particularly methyl methacrylate and styrene. The reaction in WPC polymerization is radical polymerization. Researches on the radiation sources mostly resulted in gamma-ray. Electron beam can be applied only to thin products. The future use of WPC may be for furnitures, sporting goods, decorative parts and the like. Vital study on the reduction of manufacturing costs is required, for example, the improvement of reaction and the adoption of continuous process must be considered. The raw materials for SDP are wood sawdust, vinyl monomer (mostly methyl methacrylate) and resins. Electron beam accelerators are the most preferable radiation source because of its high efficiency and safe operation. SDP shows ...
A new series of lithium ionic liquids were prepared by introducing of two electron-withdrawing trifluoroacetyl groups in borate salts containing two methoxy-oligo(ethylene oxide) groups in the structures. Successive substitution reactions of oligo-ethylene glycol monomethyl ether and trifluroacetic acid from LiBH_4 yielded the lithium salts, which were clear and colorless liquids at room temperature. The fundamental physicochemical properties, such as density, thermal property, viscosity, ionic conductivity, self-diffusion coefficients, and electrochemical stability, were measured. The lithium ionic liquids had self-dissociation ability and conducted ions even in the absence of organic solvents. New polymer electrolytes, named 'ion gels', were prepared by radical cross-linking reactions of a poly(ethylene oxide-co-propylene oxide)tri-acrylate macromonomer in the presence the lithium ionic liquid. An increase in the glass ...
In order to investigate the effect of humidity on laminar burning velocity(S), the effect of humidity on the combustion reaction and radiation intensity was studied, taking account of dilution gases such as CO/sub 2/ and Ar which has the approximately identical characteristics to exhaust gas circulation(EGR) gas used to prevent NOx discharge from engines. According to the heat reaction theory, mean specific heat(C) of mixture, mean molecular weight(M) and adiabatic flame temperature(T) etc. were said to affect S but from experimental results, the effect of M and C could be ignored, compared with the effect of T. The relationship between S and H/sub 2/O, Ar of CO/sub 2/% in mixture of diluted gases was clarified. The effect of H/sub 2/O on S was mainly caused by changes of T. The effect of radical C/sub 2/, CH and OH on radiation intensity was similar to that of H/sub 2/O and Ar and the effect of H/sub 2/O on combustion was ...
The atmospheric chemical behaviour of 1,1,1,2-tetrafluoroethane (CF{sub 3}CFH{sub 2}, HFC-134a) with respect to its rate and mechanism of degradation in the troposphere has been investigated. The rate coefficient for the reaction of (1a) CF{sub 3}CFH{sub 2}+OH{yields}CF{sub 3}CFH+H{sub 2}O has been determined in direct time-resolved experiments using laser-pulse initiation and laser long-path absorption. A value of k{sub 1a}=(4.6{+-}0.5).10{sup -15} cm{sup 3}/s at T=295 K has been found. The ratio of the rate coefficients for the reactions of the CF{sub 3}CFHO-radical with O{sub 2}, (4) CF{sub 3}CFHO+O{sub 2}{yields}CF{sub 3}CFO+HO{sub 2}, and C-C bond fission, (5) CF{sub 3}CFHO+M{yields}CFHO+CF{sub 3}+M, for T=295 K and p{sub total}=50 mbar (O{sub 2}) has been obtained to be k{sub 4}/(k{sub 5}[M])=1.5.10{sup -19} cm{sup 3}, with the individual values being k{sub 4}=2.7.10{sup -15} cm{sup 3}/s and k{sub 5}[M]=1.8.10{sup 4} ...
A method for the quantitative determination of atmospheric hydroperoxyl radical comprising: (a) contacting a liquid phase atmospheric sample with a chemiluminescent compound which luminesces on contact with hydroperoxyl radical; (b) determining luminescence intensity from the liquid phase atmospheric sample; and (c) comparing said luminescence intensity from the liquid phase atmospheric sample to a standard luminescence intensity for hydroperoxyl radical. An apparatus for automating the method is also included.
Phospholipid vesicles were found to be lysed by exposure to free radicals derived from irradiated glycine and galactose. The decomposition yield increased with vesicle concentration, and attained values of 0.0006 vesicles destroyed per radical added. Ionic charge at the phospholipid end groups was found to be more important than degree of unsaturation in determining this yield. Radicals derived from irradiated serine and alanine had no detectable lytic action at the vesicle concentrations tested.
Spectra of e.p.r. radicals in cellulose and timber gamma-irradiated at 77 and 300 K have been measured. Radiation yields and the kinetics of radicals accumulation have been studied. The effect of ionizing radiation on cellulose is the appearance of radicals resulting from rupture of C-H bonds in positions 1 and 4. Timber, additionally, forms ''lignin'' radicals. A mechanism of cellulose and timber radiolysis is suggested. ''Lignin''-type compounds present in timber protect polysaccharides from radiation-induced destruction.
Though central to our understanding of how roots perform their vital function of scavenging water and solutes from the soil, no direct genetic evidence currently exists to support the foundational model...Full Text Available
The phlebotomine sand fly Lutzomyia longipalpis is the most important vector of American visceral leishmaniasis (AVL), the disseminated and most serious form of the disease in Central...Full Text Available
Red cell transfusions are associated with the development of acute lung injury in the critically ill. Recent evidence suggests that storage induced alterations of the red blood cell (RBC) collectively...Full Text Available
Exteriorized phosphatidylserine (PS) residues in apoptotic cells trigger rapid phagocytosis by macrophage scavenger receptor pathways. Mimicking apoptosis with liposomes containing PS may represent...Full Text Available
B lymphocytes can function independently as efficient APCs. However, our previous studies demonstrate that both dendritic cells and macrophages are necessary to propagate immune responses initiated...Full Text Available
Cd36 is a small-molecular-weight integral membrane protein expressed in a diverse, but select, range of cell types. It has an equally diverse range of ligands and physiological functions, which has...Full Text Available
This paper explores for the first time the post-radiation-induced-graft polymerization on solid substrate using reversible addition-fragmentation transfer (RAFT) mechanism. Radiation-induced graft polymerization onto polymers is a potentially interesting technique to create easily new materials from highly resistant polymers, e.g. surface graft polymerization of acrylic acid (AA) onto poly(vinylidene difluoride) (PVDF) improves its surface properties without losing its excellent mechanical properties. As a consequence of the radical nature of the polymerization processes it is difficult to control molecular weight of grafted chains, and therefore design and standardize the properties of the final product. RAFT polymerization is a suitable method to obtain monodisperse polymers. The ability of the RAFT agents to control the polymer chain length could be an interesting approach to improve the grafted polymers obtained by post-radiation-induced-graft polymerization ...
The effects of the structure of a carboxylic acid on the processes of oxidation and reduction of iron ions in irradiated aqueous solutions were directly observed during irradiation. The solutions contained the mono- or dicarboxylic acid, H/sub 2/SO/sub 4/, Fe(NH/sub 4/)/sub 2/(SO/sub 4/)/sub 2/ and O/sub 2/. Th e ferrous oxidation was rather independent of the acid and its concentration, but the reduction of ferric was possible in the presence of formic, oxalic, or valeric acid only. The radical formed from the valeric acid acts similar to those formed from hydrocarbons. The G-values of oxidation and reduction of the iron ions were established. The molar extinction coefficients for oxalic and malonic complexes of ferric ions were determined. (auth)
A method of grafting lignin-containing materials is now known which allows 1-phenylethylene or 4-methyl-2-oxy-3-oxopent-4-ene graft copolymers of wood to be quantitatively made. Graft copolymer is formed by conducting a free-radical polymerization with 1-phenylethene in nitrogen-saturated, organic or aqueous/organic solvent containing a lignin source, calcium chloride, and a hydroperoxide. Grafting changes solubility and surface properties of the wood. The lignin-containing materials grafted are unbleached wood pulps produced by chemical, thermal, and mechanical pulping. Grafting wood pulp produces a wood-reinforced, thermoplastic composite. When a particular plastic is to be blended with wood, we react the wood with the monomer used to make that plastic. This creates a hydrophobic surface of the plastic on the wood. This plastic coating can readily bond to the continuous plastic phase. The products of this grafting reaction are thermoplastic ...
The industrial radiation processing using low energy electron beam (EB) accelerators lower than 300 keV offers high speed, safe technologies for the chemical conversion of thin layer coatings. Because of the nonselective mode of initiating chain reaction polymerization involving free radicals in synthetic coating layers and suitable substrates, the EB curing of the coatings on woods and papers has particular advantage. Hungary decided to start an up-to-date EB line to process cement-bound (CB) wood chipboards with pigmented acrylic coatings. The CB wood chipboards contain more than 60 % of portland cement and up to 40 % of wood particles. They are produced as large boads of 6 - 16 mm thickness. In their fireproof character and other aspects, they are similar to asbestos-cement boards without containing carcinagenic asbestos, and are stable against moisture and atmospheric influences. EB-cured acrylate coating improved further those properties, ...
Production of ozone and OH radical is required to advance the plasma chemical reactions in the NOx removal processes for combustion gas treatment. The corona discharge to the water surface is expected to induce the good conditions for the proceeding of the NO oxidation and the NO_2 dissolution removal into water. In order to get the fundamental data of the corona discharge over the water surface, the positive and negative V-I characteristics and the ozone production were measured with the multi needle and the saw-edge type of the discharge electrodes. The pulse corona characteristics were also measured with some different waveforms of the applied pulse voltage. The experiments were carried out under the atmospheric pressure and room temperature. Both the DC and the pulse corona to the water surface showed a stable and almost the same V-I characteristics as to plate electrodes though the surface of water was waved by corona wind. The positive ...
The rate coefficients for the reactions of OH radical with CH3Br and CH2Br2 were measured as functions of temperature using the laser photolysis - laser induced fluorescence method. This data was incorporated into a semiempirical model (Solomon et al., 1992) and a 2D model to calculate the steady-state ozone depletion potentials (ODP) and atmospheri lifetimes, tau, with greatly improved accuracy as compared to earlier studies. The calculated ODPs and tau are 0.65 and 1.7 years and 0.17 and 0.41 years for CH3Br and CH2Br2, respectively, using the semiempirical model. These lifetimes agree well with those calculated using a 2D model. This study better quantifies the ODPs and tau of these species which are needed inputs for discussion of possible regulation of human emissions currently under international considerations. 29 refs.
The radical cations from aziridine and azetidine have been characterized by ESR spectroscopy following their generation in the solid state by #gamma# irradiation of dilute solutions of the parent compounds in the CFCl_3 matrix at 77 K. The ESR parameters of the azetidine radical cation are typical of those for nitrogen-centered amine radical cations such as Me_2NH*"+. On the other hand, the radical cation formed from aziridine has very different ESR parameters that compare closely to those for the isoelectronic C...C ring-opened form of the oxirane radical cation and the allyl radical. The radical cation formed from azetidine is therefore assigned a ring-closed structure with the unpaired electron in a 2p/sub z/ orbital on nitrogen perpendicular to the ring plane, whereas the cation from aziridine is an allylic C...C ring-opened planar ...
The radical cations from aziridine and azetidine have been characterized by ESR spectroscopy following their generation in the solid state by ..gamma.. irradiation of dilute solutions of the parent compounds in the CFCl/sub 3/ matrix at 77 K. The ESR parameters of the azetidine radical cation are typical of those for nitrogen-centered amine radical cations such as Me/sub 2/NH*/sup +/. On the other hand, the radical cation formed from aziridine has very different ESR parameters that compare closely to those for the isoelectronic C...C ring-opened form of the oxirane radical cation and the allyl radical. The radical cation formed from azetidine is therefore assigned a ring-closed structure with the unpaired electron in a 2p/sub z/ orbital on nitrogen perpendicular to the ring plane, whereas the cation from aziridine is an allylic C...C ...
Fully fluorinated compounds (perfluoro compounds) represent a class of chemicals which include many extremely inert species-inert to both chemical reaction and photodissociation. Well known examples include SF6 and the perfluorocarbons (PFCs) CF_4 and Teflon. SF_6 is used industrially in electrical switch gear and as an atmospheric tracer. CF_4 and C_2F_6 are released into the atmosphere as a by-product of aluminum manufacture. Several perfluoro compounds have been proposed as substitutes for the ozone-destroying Freons and halons; proposed substitutes include SF_6, c-C_4F_8, C_5F_1_2, and C_6F_1_4. These chemicals were chosen in part because they do not harm the stratospheric ozone layer and were therefore considered environmentally friendly. Recently, Ravishankara et al. reported that perfluoro compounds have significant global warming potential (GWP), contributing to the greenhouse effect due to strong infrared absorption. The perfluoro compounds have ...
Objective. Cervical cancer patients who had an abandoned radical hysterectomy were evaluated for preoperative clinical predictors, complication rates, and outcomes. Study...Full Text Available
PurposeThe objective of this study is to evaluate the continence rate following reconstruction of the posterior urethral plate in robot-assisted laparoscopic radical prostatectomy...Full Text Available
Free radical formation has been implicated in the toxicity of a wide range of xenobiotics. In recent years, particular interest has been paid to compounds which can undergo a one electron reduction...Full Text Available
Introduction:Although radical prostatectomy (RP) is an effective treatment for prostate cancer, it has potentially deleterious effects on health-related quality of life (HRQoL)....Full Text Available
Despite being free of charge, treatment adherence to 7-day primaquine for the radical cure of Plasmodium vivax was estimated at 62.2% among patients along the Iquitos-Nauta road in...Full Text Available
We have undertaken a program which measures the photoelectron spectra of negative-ion beams. This experiment has afforded us direct information about these ions and the corresponding neutral radicals. Several ions and numerous radicals are believed to be crucial intermediates in combustion processes and flame chemistry. We have fabricated a spectrometer which directly measures electron affinities (EA). Knowledge of the EA and gas-phase acidity of a radical has enabled us to deduce several radical heats of formation and bond strengths.
Radicals formed in gamma-irradiated crystals of galactose and glycine were found, upon dissolution, to cause mutagenesis of Salmonella typhimurium strains TA-98 and TA-100. Although the reproducibility of the results has not been adequately determined, they suggest the possibility of developing a test to measure the mutagenic-carcinogenic potential of radiation-induced free radicals with a microbial system.
... Three prototype reactors were constructed and the photocatalysts used were TiO2 for hydroxyl radical generation, dyes such as methylene blue and rose bengal for singlet oxygen generation, and ferric chloride/hydrogen peroxide in Photo-Fenton OH radical generation. Singlet oxygen was effective against some of the pesticides but reacted slowly or not at all with others. All pesticides were degraded by OH radical generating agents (such as methylene blue)...
One important market related capability for firms which seek to develop radical innovations is the competence to involve the 'right' users at the 'right' time in the 'right' form. While former studies have identified a rather passive role of users in the radical innovation process, this paper focuses on the involvement of such users that are in the position to play an active role as inventors and (co)-developers. A multiple case study analysis was conducted in the field of medical technology. Five radical innovation projects within four firms were selected including medical robots and computer-assisted navigation systems. The case study analysis reveals that firms who closely interact with specific users benefit significantly for their radical innovation work. These users have a high motivation toward new solutions, are open to new technologies, possess diverse competencies, and are embedded into a very ...
One-electron reduction of the square-planar nickel precursor (PNP)NiCl ( 1) (PNP (-) = N[2-P(CHMe 2) 2-4-methylphenyl] 2) with KC 8 effects ligand reorganization of the pincer ligand to assemble a Ni(I) dimer, [Ni(mu 2-PNP)] 2 ( 2), containing a Ni 2N 2 core structure, as inferred by its solid-state X-ray structure. Solution magnetization measurements are consistent with a paramagnetic Ni(I) system likely undergoing a monomer dimer equilibrium. The room-temperature and 4 K solid-state X-band electron paramagnetic resonance (EPR) spectra display anisotropic signals. Low-temperature solid-state X-band EPR data at 4 K reveal rhombic values g z = 1.980(4), g x = 2. 380(4), and g y = 2.225(4), as well as a forbidden signal at g = 4.24 for the Delta M S = 2 half field transition, in accord with 2 having two weakly interacting metal centers. Utilizing an S = 1 model, full spin Hamiltonian simulation of the low-temperature EPR spectrum on the solid sample was achieved by applying a nonzero ...
Abstract Acid-treated cobia (Rachycentron canadum) skin was extracted in a retort (121C) to obtain retorted skin gelatin hydrolysates (RSGHs) containing antioxidant peptides with noticeable antioxidant properties. To improve the antioxidant activity of cobia RSGHs, five processing factors including alkali concentration, alkali pretreatment time, phosphoric acid concentration (PC), water/skin ratio (WS) and retorting time (RT) in RSGH production were screened using a fractional factorial design to identify critical factors. It indicated that PC, WS and RT had significant effects on ,-diphenyl--picrylhydrazyl (DPPH) scavenging by RSGHs. Subsequently, the optimization of PC, WS and RT on the DPPH scavenging of RSGHs was studied using a central composite design to collect data that resulted in...
PWR primary circuit radiolysis model describes oxygen/hydrogen behavior in the Westinghouse Sizewell B 4-loop PWR (SNUPPS design). The effect of oxygen ingress have also been evaluated using the same model. There is clear agreement from experimental and modelling data that the dissolved hydrogen concentration required to suppress radiolysis decreases as the temperature increases. There is good evidence from the study at the Belleville PWR that {approx}5 cc(STP)kg{sup -1} H{sub 2} is sufficient to suppress radiolysis during power operation. Modelling indicates that the minimum hydrogen concentration is about 0.5 cc (STP)kg{sup -1} at PWR operating temperatures and that the presence of boric acid has little effect on this value, although it does increase the steady-state concentration of H{sub 2}O{sub 2}. Downstream of the core the concentrations of both oxygen and hydrogen peroxide fall by about two orders of magnitude at full power due to reaction with ...
Radical cations of various 3-methylalkanes (C_6-C_1_4) have been produced and stabilized by #gamma#-irradiation of the corresponding neutral compounds in saturated chlorofluorocarbon and perfluorocarbon matrices at 77 K. The perfluorocarbon matrices appeared more suitable for studies of the lighter radical cations, whereas the chlorofluorocarbon matrices were more suited for studies of the heavier radical cations; intermediary cations could be studied in both types of matrices. After irradiation, electronic absorptions associated with both the matrix and the alkane additive were observed. Pure spectra of the 3-methylalkane radical cations were obtained by difference spectrometry, after selective elimination of these cations by illumination. The electronic absorption spectra of the 3-methylalkane radical cations consist in all cases of a single broad absorption band. The spectral ...
The mechanism for afterglow suppression in codoped CsI:Tl,Eu reported in the preceding paper was investigated by combined radioluminescence and thermoluminescence experiments. Model rate equations informed by these experiments were employed to simulate afterglow. It was found that codoping with europium introduces deep electron traps, with room-temperature glow peaks, that effectively scavenge the electrons from shallow traps associated with thallium, thus suppressing afterglow in the time domain of tens of milliseconds.
Effects of gamma irradiation on the physiological effectiveness of Korean medicinal herbs were investigated. The physiological effectiveness including antioxidant and anticomplement function, nitrite scavenging and electron donating ability of Korean medicinal herbs by gamma irradiation at 10 kGy did not differ from that of the nonirradiated control.
The kinetics of HO{sub 2} radicals in UV-irradiated frozen dilute solutions of H{sub 2}O{sub 2} were followed by the ESR technique. Radical disproportionations at the irradiation temperature were found to be adequately described in terms of dispersive kinetics by a second-order equal-concentration kinetic equation with rate parameters changing non-monotonically in the temperature range 100-200 K. These changes are thought to occur due to well separated structural relaxation regions of polycrystalline ice in the above temperature range. (author).
PurposeTo conduct a retrospective analysis within a large university teaching hospital, comparing outcomes between patients receiving either radical surgery or radiotherapy as curative treatment for bladder cancer.Patients and MethodsBetween March 1996 and December 2000, 169 patients were treated radically for muscle-invasive bladder cancer. Data were collected from patient notes. Statistical analyses were performed using Kaplan-Meier methods and Cox proportional hazards regression analysis to compare radiotherapy and surgical outcome data.ResultsThere was no difference in overall, cause-specific, and distant recurrence-free survival at 5 years between the two groups, despite the radiotherapy group being older (median age, 75.3 years vs. 68.2 years). There were 31 local bladder recurrences...
ROBOT-ASSISTED RADICAL LAPAROSCOPIC PROSTATECTOMY WAKE FOREST UNIVERSITY BAPTIST MEDICAL CENTER WINSTON-SALEM, NC 00:00:08 ANTHONY ATALA, MD: I would like ...
Penile rehabilitation therapy following radical prostatectomy is a much debated topic. Erectile dysfunction is still a significant contributor to postoperative morbidity following radical prostatectomy, despite meticulous nerve-sparing technique. Secondary smooth muscle changes in the penis have been identified as the underlying causes of penile atrophy, veno-occlusive dysfunction, and fibrosis. Initial observations that intracavernous injection therapies used on a regular basis postoperatively resulted in improvements in the return of spontaneous erectile function led to the development of penile rehabilitation protocols. Chronic dosing of PDE-V inhibitors is now commonly used by urologists after radical prostatectomy. Despite the current enthusiasm of penile rehabilitation therapy, current scientific evidence with clinical trials is still limited. PMID:19255627
The Mitochondrial Free Radical Theory of Aging (MFRTA) is currently one of the most widely accepted theories used to explain aging....Full Text Available
The n3 and n4 vibrational transitions of CH3 and CD3 isolated in solid parahydrogen were studied by high-resolution infrared spectroscopy. The radicals were produced by in situ UV photolysis of methyl iodides trapped in solid parahydrogen. The observed spectra showed clear rotational fine structures, which were subjected to further splitting due to the electrostatic field of solid parahydrogen. The molecular constants and crystal field parameters of the radicals in solid parahydrogen were determined by analyzing the spectral structures of the n3 and n4 transitions of CD3 by the crystal field theory. The rotational constants of the CD3 radical were found to be only a few percent smaller than those in the gas phase. The determined crystal field parameters indicated significant quantum effect...
There are several methods of generating OH free radicals from ozone and/or hydrogen peroxide and ultraviolet light. They all have in common that the OH free radicals originate in one single source only whereas in the combination of ozone with ionizing radiation two simultaneous working sources for the OH free radicals exist. The resulting higher OH free radical concentration makes this process especially apt for the remediation of low level contaminated groundwater as for example trichloroethylene (TCE) contamination in the sub-ppm range. A cost comparison between O_3/UV and O_3/electron beam for remediation of a groundwater contaminated with 100 ppb TCE indicated that for a throughput of about 5 million gallons/day the O_3/electron beam process is more cost-effective. (authors).
With an objective to know coal condensation structure which has influence on coal conversion reaction, an attempt was made on quantitative evaluation of hydrogen bonding in coal. Using as test samples the VDC made from Taiheiyo coal swollen by tetralin and vacuum-dried, and its pyrolyzed char, DSC measurement and Fourier transform infrared spectroscopy (FT) were performed. An FT spectrum comparison revealed that the VDC swollen at 220{degree}C has the hydrogen bonding relaxed partly from the original coal. However, since the change is in a huge coal molecular structure restraining space, it has stopped at relaxation of the bonding energy without causing separation as far as free radicals. On the other hand, the DSC curve shows that the VDC has slower endothermic velocity than the original coal. In other words, the difference in heat absorption amounts in both materials is equivalent to the difference of enthalpy ({Delta} H) of both materials, ...
Ternary copper(II) complexes [Cu(L1)B](ClO4) (1, 2) and [Cu(L2)B](ClO4) (3, 4), where HL1 and HL2 are tridentate NSO- and ONO-donor Schiff bases and B is a heterocyclic base, viz. dipyrido[3,2-d:2',3'-f]quinoxaline (dpq, 1 and 3) or dipyrido[3,2-a:2',3'-c]phenazine (dppz, 2 and 4), were prepared and their DNA binding and photoinduced DNA cleavage activity studied. Complex 1, structurally characterized by single-crystal X-ray crystallography, shows an axially elongated square-pyramidal (4 + 1) coordination geometry in which the monoanionic L1 binds at the equatorial plane. The NN-donor dpq ligand exhibits an axial-equatorial binding mode. The complexes display good binding propensity to calf thymus DNA, giving a relative order 2 (NSO-dppz) > 4 (ONO-dppz) > 1 (NSO-dpq) > 3 (ONO-dpq). They cleave supercoiled pUC19 DNA to its nicked circular form when treated with 3-mercaptopropionic acid (MPA) by formation of hydroxyl radicals as the cleavage active species ...
Esters of dihydric alcohols with alkenylphosphonic or alkenylphosphinic acids which are polymerizable by free radicals are described. They are combined with polymer binders, in particular water-soluble polymers, and photoinitiators forming free radicals to give photopolymerizable mixtures which are suitable for the production of photoresists and printing plates. The mixtures display low heat-sensitivity and have long shelf lives. (author) 1 tab.
Practical procedures were developed for large-scale microbial decontamination of dry egg powder and gelatine with gamma radiation ("6"0Co). The formation and lifes of free organic radicals in these materials were examined by ESR measurements of powder samples. The concentration of these radicals was studied in dependence on the time of storage. Secondary oxidation of egg fats by air oxygen was investigated. Sensoric tests of irradiated gelatine, both in powder and hydrogel form, were performed. (author). 4 figs., 2 tabs., 2 refs.
The author is exploring the efficiency of pulsed plasma processing in the removal of nitrogen dioxide, nitrogen oxide, and other pollutants. This process uses an electrical discharge to create chemical radicals from air molecules. These radicals can react with pollutants and form harmless compounds. Additives such as hydrocarbons are also used to improve the efficiency of the removal. The efficient removal of nitrogen dioxide has required the presence of dilute aqueous solution of ammonia.
The radiation reduction of bis(1-ethylimidazole)tartratoplatinum(II) (EITPt(II)) complexes in methanol-water solution have been examined. The yields of Pt(I) depend on the presence of O{sub 2} in solutions as well as the dose applied. The rate constants of e{sub s}{sup -} scavenging by EITPt(II) and cis(diammine-1,1-cyclobutanedicarboxylato) platinum(II) (CBDCAPt(II)) have been determined by pulse radiolysis to be equal to 5.4 x 10{sup 9} and 6.4 x 10{sup 9} M{sup -1} s{sup -1}, respectively. The efficiencies of e{sub t}{sup -} scavenging by EITPt(II) and the rate of e{sub t}{sup -} photobleaching have also been determined in LiCl : H{sub 2}O : CH{sub 3}OH and MgCl{sub 2} : H{sub 2}O : CH{sub 3}OH glasses, respectively. (author).
Conduction-band electrons, formed by pulse radiolysis of Degussa P25 TiO_2 particles, have been monitored by time-resolved microwave conductivity and found to undergo equilibrium localization and eventual recombination at the particle surface. In the presence of isopropyl alcohol recombination is retarded due to surface hole scavenging. The particle bulk can then be pumped with mobile electrons, which survive for seconds.
Hyperquenching of liquid water with cooling rates of 10{sup 6}-10{sup 7} K s{sup -1} yields glassy water. Upon {gamma}-irradiation at 77 K, the only paramagnetic species accumulating in hyperquenched glassy water are the hydroxyl and hydroperoxyl radicals. There are no hydrogen atoms or electrons seen by the ESR technique. For irradiation doses up to about 70 kGy, the relative contributions of hydroxyl and hydroperoxyl radicals to the total amount of paramagnetic species remain virtually constant. The total amount of paramagnetic species, n, is sublinear in dose, d, well approximated by n=8.55x10{sup 16}d{sup 0.8} for n in spin g{sup -1} and d in kGy.
Kinetics of postradiation polymerization of triethylene glycol ..cap alpha.., ..omega..-dimethacrylate has been studied by calorimetric method. The low-temperature radiolysis has been studied by ESR method. The radiation-chemical yield of radicals on ..gamma..-irradiation by /sup 60/Co is determined being equal to 6+-1 1/100 ev. Transformation of the radicals spectrum into the spectrum of propagating macroradicals proceeds at 140 K. After the transition from glassy to liquid state (Tsub(g)=193 K) the intensive postpolymerization begins. During the polymerization the disappearance of radicals is observed. For the low-temperature region the effective activation energy of polymerization is determined beina equal to 50.7+-0.8 kJ/mol.
The effects of TANOL radical have been examined on chemical shifts and relaxation rates of /sup 109/Ag NMR in aqueous solution of silver salts. The silver ion in aqueous solution is found to coordinate with TANOL radical. A small amount of TANOL is added as a doping agent(0.020M), since /sup 109/Ag signals are obtained for (1.0M) silver ion within 30 minutes. The /sup 109/Ag chemical shifts of silver salt in aqueous solutions were found within the range of 0 to -1000 ppm relative to that of 1.0M AgNo/sub 3/.
In the treatment of prostatic cancer using a newly proposed intermittent multiportal therapy (DIMT), acute reactions, change in tumor marker levels, and complications more than 6 months after treatment were evaluated. From June 1989 to September 1990, 26 patients with prostatic cancer (stage A2, 3 patients; B, 9; C, 2; D, 10; recurrence, 2) were treated. Fifteen patients were followed up for more than one year, with a mean period of 11.6 months. The treatment schedule is 52.5 Gy in 16 fractions in 4 weeks for radical treatment, and 30.0 Gy in 8 fractions in 2 weeks for palliative treatment. The 360 degree rotation about the patient was divided into 16 fractions, and 2 opposing fractions were used in one day as parallel opposed portals to treat the target volume. The fractions were serially treated one per day, so that 8 treatment days produced a total dose of distribution similar to that for conventional conformational therapy. The size of the ...
Exercise training is known to induce an increase in free radical production potentially leading to enhanced muscle injury. Vitamins C and E are well known antioxidants that may prevent muscle cell damage....Full Text Available
The authors report on a search for pair production of first-generation scalar leptoquarks (LQ) in p{bar p} collisions at {radical}s = 1.96 TeV using an integrated luminosity of 252 pb{sup -1} collected at the Fermilab Tevatron collider by the D0 detector. They observe no evidence for LQ production in the topologies arising from LQ{ovr LQ} {yields} eqeq and LQ{ovr LQ} {yields} eqvq, and derive 95% C.L. lower limits on the LQ mass as a function of {beta}, where {beta} is the branching fraction for LQ {yields} eq. The limits are 241 and 218 GeV/c{sup 2} for {beta} = 1 and 0.5, respectively. These results are combined with those obtained by D0 at {radical}s = 1.8 TeV, which increases these LQ mass limits to 256 and 234 GeV/c{sup 2}.
Our group has developed a physician-operated inpatient order-entry system (BICS-OE). Mindful of the problems inherent in bringing a radical cultural change such as this to the hospital, we conducted...Full Text Available
BackgroundThe optimal treatment for locally recurrent rectal cancer (LRRC) is still a matter of debate. This study assessed the outcome of LRRC patients treated with multimodality...Full Text Available
Background. The Free Radical Theory of Aging mechanistically links oxidative stress to aging. Okinawa has among the world's longest-lived populations but oxidative stress in this...Full Text Available
Recurrent tumour after radical pancreaticoduodenectomy may cause obstruction of the small bowel loop draining the liver. Roux-loop obstruction presents a particular therapeutic challenge, since the...Full Text Available
The CNS can exhibit features of inflammation in response to injury, infection or disease, whereby resident cells generate inflammatory mediators, including cytokines, prostaglandins, free radicals and...Full Text Available
Because copper catalyzes the conversion of H2O2 to hydroxyl radicals in vitro, it has been proposed that oxidative DNA damage may be an important component of copper toxicity....Full Text Available
SUMMARYA gene eam in Clostridium difficile encodes a protein that is homologous to lysine 2,3-aminomutase (LAM) in many other species but does...Full Text Available
By using EPR measurements of radiation-induced radicals it is possible to utilize human fingernails to estimate radiation dose after-the-fact. One of the potentially limiting factors in this...Full Text Available
ObjectiveThe aim of this study was to ascertain whether all cervical cancer patients who received adjuvant concurrent chemoradiation (CCRT) for high risk of treatment failure after...Full Text Available
Two additional hyperfine components of the interstellar radical C3H were detected. In addition, methanol was discovered in interstellar clouds. The abundance of HCCN and various chemical isomers in molecular clouds was investigated.
OBJECTIVE: To test the hypothesis that perioperative transfusion of allogeneic and autologous red blood cells (RBCs) stored for a prolonged period speeds biochemical recurrence of prostate cancer...Full Text Available
The free radical theory of ageing posits that accrual of oxidative damage underlies the increased cellular, tissue and organ dysfunction and failure associated with advanced age. In support of this...Full Text Available
RC-12 [1,2-dimethoxy-4-(bis-diethylaminoethyl)-amino-5-bromobenzene] was evaluated for prophylactic, radical curative, and suppressive activities against infections with Plasmodium cynomolgi and subacute...Full Text Available
Chlorophyll a, chlorophyll b, and bacteriochlorophyll a in aqueous micellar solutions of Trition X 100 (2%) are readily oxidized by pulse-radiolytically generated N_3., Br_2"-., and (SCN)_2"-. radicals at nearly diffusion-controlled rates. The kinetic study suggests that pigment molecules occupy multiple sites in the micelle. Pheophytin a is only oxidized by N_3. and Br_2"-. radicals. The absolute spectra and the molar extinction coefficients of chlorophyll a, bacteriochlorophyll a, chlorophyll b, and pheophytin a cations have been determined. The chlorophyll a cation has been observed in the presence of pigment aggregates.
Forty-three patients with basal and squamous cell carcinomata arising on the pinna were treated radically using a 10 MeV electron beam. The technique and dosage are described and discussed. Primary cancer control with retention of the pinna was achieved in 34 patients. Salvage pinnectomy was performed in four patients for recurrence and one patient for radiation necrosis. Two patients with large primary tumours failed to resolve and died of their disease. The advantages for the patient of the policy of primary radical electron beam therapy are discussed.
The authors present a measurement of the B{sub s}{sup 0} meson lifetime using fully and partially reconstructed hadronic decays B{sub s}{sup 0} {yields} D{sub s}{sup -} {pi}{sup +}(X) followed by D{sub s}{sup -} {yields} {phi}{pi}{sup -}. The data sample was recorded with the CDF II detector at the Fermilab Tevatron and corresponds to an integrated luminosity of 1.3 fb{sup -1} from p{bar p} collisions at {radical}s = 1.96 TeV.
Purpose: To conduct a retrospective analysis within a large university teaching hospital, comparing outcomes between patients receiving either radical surgery or radiotherapy as curative treatment for bladder cancer. Patients and Methods: Between March 1996 and December 2000, 169 patients were treated radically for muscle-invasive bladder cancer. Data were collected from patient notes. Statistical analyses were performed using Kaplan-Meier methods and Cox proportional hazards regression analysis to compare radiotherapy and surgical outcome data. Results: There was no difference in overall, cause-specific, and distant recurrence-free survival at 5 years between the two groups, despite the radiotherapy group being older (median age, 75.3 years vs. 68.2 years). There were 31 local bladder recurrences in the radiotherapy group (24 solitary), but there was no significant difference in distant recurrence-free survival. In a more recent (2002-2006) ...
Abstract Superoxide dismutase (SOD) is ubiquitous in aerobic organisms and constitutes the first link in the enzyme scavenging system of reactive oxygen species. In the present study, species and organ diversity of SOD activity in a solution and in an in-gel assay system, as well as the effects of hydrogen peroxide (H2O2) on SOD activity, were investigated. In a solution assay system, SOD activity of jackfruit root, shoot, leaves, axes, and cotyledons, of maize embryos and endosperms, of mung bean leaves and seeds, of sacred lotus axes and cotyledons, and of rice and wheat leaves was increased by 1-15 mmol/L H2 O2. However, SOD activity in rice root and seeds, maize roots and leaves, mung bean roots and shoots, and wheat seeds was decreased by 1-15 mmol/L H2O2. The SOD activity of wheat ro...
Monthly sampling of slightly alkaline arsenic-rich stream in the Mokrsko gold deposit revealed seasonal variations in dissolved Zn, Cu, As and Mo. Concentrations of trace metal cations (Zn, Cu) increased as much as 330 and 178%, respectively, from minimum mean values at autumn to maximum mean values at spring. In contrast, concentrations of trace element oxyanions (As, Mo) revealed opposite seasonal pattern with increase to 189% (As) and 123% (Mo) during summer?autumn, indicating that in-stream biogeochemical process(es) played the main role in controlling the seasonal variations of these trace elements. The trace elements were mainly scavenged by low crystalline Mn oxyhydroxide and Fe oxyhydroxide (ferrihydrite). Results are consistent with sorption and coprecipitation processes controlli...
We quantified the resistance levels of transgenic rice plants, expressing Myxococcus xanthus protoporphyrinogen oxidase (PROTOX) in chloroplasts and mitochondria, to PROTOX inhibitors, acifluorfen, oxyfluorfen, carfentrazone-ethyl, and oxadiazon. We also determined whether active oxygen species-scavenging enzymes are involved in the resistance mechanism of transgenic rice. The transgenic rice line M4 was about >200-fold more resistant to oxyfluorfen than the wild-type (WT). M4 was also resistant to acifluorfen, carfentrazone-ethyl, and oxadiazon, but did not show multiple resistance to imazapyr and paraquat, which have different target sites. Acifluorfen, oxyfluorfen, carfentrazone-ethyl, and oxadiazon reduced the chlorophyll content in leaves of WT, but had minimal or no effect on M4. The...
The performance of the gaseous fuel supply and its influence on hydrocarbon (HC) emissions of dual-fuel engines have been investigated. A new design of manifold respirators with mixers is also presented in the paper. The design of the gaseous fuel supply system has a great influence on HC emissions in the dual-fuel engine at light load. The problem of scavenging is discussed and solved by using the manifold respirators in the dual-fuel engine. It performs the function of retarding the gaseous fuel entry timing from the moment of intake valve opening, and its delaying effects have been measured and tested. Experimental results show that the manifold respirator gives the best performance in reducing HC emissions compared with a common pipe mixer and a respirator with bo miser. In addition, the mixing effects are sensitive to the mixer configuration. (Author)
The function of selenium in an organism is mediated mostly by selenoproteins including glutathione peroxidase. Glutathione peroxidase is a potent anti-oxidative enzyme, scavenging a variety of peroxides. The green alga Scenedesmus quadricauda was used to investigate the relationship between the toxicity of selenium and the glutathione peroxidase activity. Selenium resistant strains SeIV and SeVI were synchronized and grown in high concentrations of Se (selenite or selenate). As a measure of selenium toxicity the EC50 values were determined. During growth of the untreated wild type, glutathione peroxidase activity increased slightly and then declined gradually until the end of the cell cycle. A similar pattern was observed in untreated resistant strains and when resistant strains were grown...
Data on the reactions of thiocyanogen and thiocyanogen halides with unsaturated compounds are systematised. The kinetic and stereo- and regiochemical regularities of these reactions are analysed. The bibliography includes 81 references.
Sida cordifolia is a plant belonging to the Malvaceae family used in many ayurvedic preparations. This study aimed at assessing the effects of ethanolic extract of Sida cordifolia root on quinolinic acid (QUIN) induced neurotoxicity and to compare its effect with the standard drug deprenyl in rat brain. Rats were divided into six groups: (1) control group (2) QUIN (55 microg/100 g bwt/day) (3) 50% ethanolic plant extract treated group (50 mg/100 g bwt/day) (4) Deprenyl (100 microg/100 g bwt/day) (5) QUIN (55 microg/100 g bwt/day) + 50% ethanolic plant extract treated group (50 mg/100 g bwt/day) (6) QUIN (55 microg/100 g bwt/day) + Deprenyl (100 microg/100 g bwt/day). At the end of the experimental period a status of lipid peroxidation products, protein peroxidation product, activities of the scavenging enzymes and the activities of the inflammatory markers were analyzed. Results revealed that the lipid peroxidation products decreased and the activities of the ...
The A2P-X2+Dv=-3 bands of the 12C14N radical have been observed by time-resolved Fourier transform spectroscopy in the 1850-3100cm-1 region with a wavenumber resolution of 0.025cm-1. The radical was produced in a pulsed positive column discharge in a cyanogene and helium mixture. Seven bands of v=0-3, 1-4, 2-5, 3-6, 4-7, 5-8, and 6-9 were analyzed to give the molecular constants of each state by least-squares fitting of 801 lines. The pulsed discharge was found to be efficient for production of CN in the excited A2P state. The vibrational excitation temperature was determined to be 6680+-835K and 6757+-534K for the A2P and X2+ states, respectively. The population of the A2P was found to be 4% of that of the X2+ state in the time after turning off the discharge.
A novel technique is proposed for the growth of an InN film on a GaN/Al2O3(0001) template by radio-frequency plasma-excited molecular beam epitaxy (RF-MBE). The method involves 1) InN growth under an In-rich condition and 2) additional nitrogen radical irradiation after the InN growth under an In-rich condition. Excess In that appeared on the InN surface in the InN growth under an In-rich condition is transformed to InN by the additional nitrogen radical irradiation. The effective V/III ratio is easily controlled by monitoring the intensity in a reflection high-energy electron diffraction (RHEED) pattern. The growth of the InN film by repeating the InN growth under an In-rich condition and the additional nitrogen radical irradiation is also demonstrated. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)
The present study was undertaken in 27 children with localized Ewing's sarcoma treated at our hospital. In 9 cases the lesion was central and in 18 peripheral. Treatment consisted of: 1) Chemotherapy with 6 drugs (vincristine, cyclophosphamide, methotrexate, bleomycin, dactinomycin and doxorubicin) for one year in all patients; 2) Radiotherapy in 24 patients at a dose of 30-40 Gy in the entire bone with a booster dose of 10-15 Gy in the lesion. In 7 patients debulking surgery was performed followed by irradiation. Two cases with tumor in expendable bones and one with extensive destructive lesion in the tibia underwent radical surgery. One patient suffered local recurrence (femur) and 6 developed distant metastases. The remaining 20 (74%) patients were alive and tumor-free after follow-up periods of 17-80 months. Among the 12 patients with extremity lesions who were alive, 7 (58%) had minimal or mild treatment sequelae, 2 moderate, and 3 severe sequelae but no ...
To elucidate the mechanism of sunlight-induced skin damage, guinea pigs exposed to UV light (280-320 nm, UV B, 4J/cm"2) and a homogenate of the epidermis was examined by means of the thiobarbituric acid (TBA) test. Three hours after the exposure, TBA-malondialdehyde adducts had increased while glutathione reductase activity had decreased, indicating lipid peroxidation. To detect the initial species, spin trapping with 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) was applied to a suspension of illuminated epidermal cells (0.5 J/cm"2). An ESR signal obtained only with irradiation comprised a 1 : 2 : 2 : 1 quartet [a (N) =a (#beta#H) =1.49 mT] attributable to a spin adduct of hydroxyl radicals. These results suggest that sunlight exposure of skin may lead to hydroxyl radical generation and simultaneous lipid peroxidation. (author).
Bacteriophage M13 mp10 DNA were irradiated with near-UV light in the presence of tetracycline derivatives and primed with synthetic oligonucleotide to be used for DNA synthesis using Escherichia coli DNA polymerase. Chain terminations were observed by denaturing polyacrylamide gel electrophoresis and mapped precisely. All the synthesis stops occurred before or at the level of guanine residues, showing that the photoreaction mediated by tetracycline derivatives led to a preferential alteration of guanine residues. These lesions were demonstrated to be induced in DNA through a pathway involving singlet oxygen. Tetracycline derivatives also photoinduced the breakage of the DNA sugar-phosphate backbone monitored by the conversion of supercoiled phi X174 DNA to a relaxed form. This lesion was shown to be initiated by hydroxyl radicals. The production of this free radical has been confirmed by electron paramagnetic resonance (EPR) spin trapping ...
Two measurement methods to determine the rate of neutral free radical production by the photo-deionization of negative ion beams (PDINIB) are introduced. These methods, namely, photoelectron-current measurement by low-frequency electro-modulation probe (PMMP) and measurement of decrease in the negative-ion beam current (DNIC) were employed to evaluate the production rate in a trial surface-processing apparatus developed in the author's laboratory utilizing a steady-flux refined beam of neutral free radicals (RBNR) produced by the PDINIB procedure. A {sup 63}Cu{sup -} negative ion beam of kinetic energy E{sub i} varied up to 15 keV was irradiated with a 514.5 nm visible light beam from a 25 W CW Ar{sup +} ion laser. The detection limit of the production rate by the PMMP setup was as high as 6 x 10{sup 9} s{sup -1} under the condition that E{sub i}=15 keV, the negative-ion beam current I{sub i}=4 {mu}A and the laser power P=6 W. The DNIC ...
We summarize the predictions of different models for total #gamma##gamma# cross-sections. The experimentally observed rise of #sigma#_#gamma#_#gamma# with s radical _#gamma#_#gamma#, faster than that for #sigma#_p_-_b_a_r_p, #sigma#_#gamma#_p is in agreement with the predictions of the Eikonalized Minijet Models as opposed to those of the Regge-Pomeron models. We then show that a measurement of #sigma#_#gamma#_#gamma# with an accuracy of < or approx. 8-9% (6-7%) is necessary to distinguish among different Regge-Pomeron type models (the different parameterisations of the EMM models) and a precision of < or approx. 20% is required to distinguish the predictions of the EMMs and of those models which treat 'photon like a proton', for the energy range 300< s radical_#gamma#_#gamma# <500 GeV. We further show that the difference in model predictions for #sigma#_#gamma#_#gamma# of about a factor 2 at s radical ...
Recent work has shown that natural hydrocarbon emissions can significantly affect the levels of urban and regional tropospheric ozone. We report on the reactivities of these biogenic trace gases, particularly isoprene, focusing on their importance in the production of aldehydes and peroxy radicals, leading to increased levels of hydrogen over regional forests. Hydrogen peroxide can lead to the wet oxidation of sulfur dioxide to acidic sulfate in aerosols, fogs, and clouds. In turn, acidic sulfate can act to as a light scattering aerosol and a source of cloud condensation nuclei (CCN), potentially leading to global cooling. Aerosol sulfate and other dissolved organic and inorganic compounds can also play important roles as a greenhouse species in the lower troposphere.
The authors search Z{prime} bosons in dielectron events produced in p{bar p} collisions at {radical}s = 1.96 TeV, using a 0.45 fb{sup -1} dataset accumulated with the CDF II detector at the Fermilab Tevatron. To identify the Z{prime} {yields} e{sup +}e{sup -} signal, both the dielectron invariant mass distribution and the angular distribution of the electron pair are used. No evidence of a signal is found, and 95% confidence level lower limits are set on the Z{prime} mass for several models. Limits are also placed on the mass and gauge coupling of a generic Z{prime}, as well as on the contact interaction mass scales for different helicity structure scenarios.
The incidence of hilar cholangiocarcinoma is very rare worldwide. Radical resection is the only prognostic factor for long survival in patients with hilar cholangiocarcinoma. Postoperative radiation therapy can improve local control and survival rates for patients with palliative resection, but it remains controversial in patients with radical resection. Biliary drainage can effectively release bile duct obstruction for the majority of patients with locally advanced disease, and may even prolong survival when combined with radiation therapy. Radiation therapy includes extrernal beam therapy alone, external beam therapy with intraluminal brachytheapy and new radiation technique, such as three dimentional conformal therapy and intensity modulated radiation therapy. The propective randomized clinical study is needed for further investigation in the role of combined modality therapy especially for hilar cholangiocarcinoma. (authors)
Purpose. To compare erectile function (EF) recovery of patients treated by early penile rehabilitation therapy (PRT) with sildenafil and with control group. Method. Forty men treated by bilateral nerve sparing radical prostatectomy (NSRP) and with a normal pre-operative EF were enrolled. Fourteen days after surgery, they were randomised to a flexible-dose sildenafil group and to a control group. The International Index of Erectile Function (IIEF) questionnaire was completed before surgery and at 3, 6, 12 and 24 weeks after NSRP. Results. In the group treated, the mean IIEF score before surgery was 26.2 and 14.1, 16.2, 22.5 and 25.2 at 3, 6, 12 and 24 weeks after NSRP, respectively. In the control group, the respective scores were 26.5 and 12.4, 15.8, 15.3 and 17.4. There was a significant ...
ABSTRACT Introduction. Postprostatectomy erectile dysfunction (ED) remains a serious quality-of-life issue. Recent advances in the understanding of the mechanism of postprostatectomy ED have stimulated great attention toward penile rehabilitation. Aim. This review presents and analyzes a contemporary series of the recent medical literature pertaining to penile rehabilitation therapy after radical prostatectomy (RP). Main Outcome Measures. The laboratory and clinical studies related to penile rehabilitation are analyzed. The validity of the methodology and the conclusion of the findings from each study are determined. Methods. The published and presented reports dealing with penile rehabilitation following RP in human and cavernous nerve injury in animal models are reviewed. Results. Exciti...
The optimal management of men with very favorable clinicopathological factors who develop biochemical recurrence (BCR) after radical prostatectomy (RP) has not been previously reported. Both local and systemic recurrences are unlikely in this cohort. This study examines their management and outcomes. Between October 2000 to March 2010, 1627 men underwent open RP by a single surgeon. In all, 448 (27.5%) met the following criteria for extremely low risk disease: preoperative PSA level <10?ng?ml?1, clinical stage T1c/T2a, Gleason score ?6, estimated cancer volume in the surgical specimen ?5% and no evidence for positive surgical margin. Undetectable PSA was defined as ?0.04?ng?ml?1. BCR was defined as PSA ?0.2?ng?ml...
Five arylethylenes with 1-naphthyl, 2-naphthyl, and phenyl groups in 1,2-positions have been studied for singlet-mediated charge-transfer interactions with several amines and paraquat dication. 1-Phenyl-2-(2-naphthyl)ethylene and 1,2-di(2-naphthyl)ethylene exhibit distinct dependence of exciplex emission maxima and lifetimes, and fluorescence quenching constants, on excitation and/or monitoring wavelengths; this is in conformity with the existence of ground-state rotamers for these systems, wtih distinguishable absorption-emission spectra and fluorescence lifetimes. The fluorescence quenching by aromatic amines and paraquat dication occurs with rate constants in the limit of diffusion control and is accompanied by the formation of radical ions in polar solvents (acetonitrile). The transient spectra and kinetics associated with the radical ions, observed by 337.1- and 355-nm laser flash photolysis, are also reported. 10 figures, 4 tables.
Evidence is reported for a narrow structure near the J/{psi}{phi} threshold in exclusive B{sup +} {yields} J/{psi}{phi}K{sup +} decays produced in {bar p}p collisions at {radical}s = 1.96 TeV. A signal of 14 {+-} 5 events, with statistical significance in excess of 3.8 standard deviations, is observed in a data sample corresponding to an integrated luminosity of 2.7 fb{sup -1}, collected by the CDF II detector. The mass and natural width of the structure are measured to be 4143.0 {+-} 2.9(stat) {+-} 1.2(syst) MeV/c{sup 2} and 11.7{sub -5.0}{sup +8.3}(stat) {+-} 3.7(syst) MeV/c{sup 2}.
Abstract Purpose: We evaluated complications of urologic laparoscopic surgery at our institution. Patients and Methods: From December 1991 to January 2009, 1017 urologic laparoscopic surgical procedures were performed in Kansai Medical University, including 277 radical prostatectomies, 13 donor nephrectomies, 74 partial nephrectomies, 158 radical nephrectomies, 55 pyeloplasties, 97 nephrouretectomies, 54 simple nephrectomies, 128 adrenalectomies, 34 varicocelectomies, and 127 other procedures. Medical records of each procedure were retrospectively evaluated. The difficulty of each procedure was classified according to the European Scoring System (ESS). Intraoperative and postoperative complications were graded according to the Satava and Clavien classifications, respectively. Results: Amon...
I describe a search for anomalous production of Z pairs through a new massive resonance X in 2.5-2.9 fb{sup -1} of p{bar p} collisions at {radical}s = 1.96 TeV using the CDFII Detector at the Fermilab Tevatron. I reconstruct Z pairs through their decays to electrons, muons, and quarks. To achieve perhaps the most efficient lepton reconstruction ever used at CDF, I apply a thorough understanding of the detector and new reconstruction software heavily revised for this purpose. In particular, I have designed and employ new general-purpose algorithms for tracking at large {eta} in order to increase muon acceptance. Upon analyzing the unblinded signal samples, I observe no X {yields} ZZ candidates and set upper limits on the production cross section using a Kaluza-Klein graviton-like acceptance.
An experiment has been performed to investigate the chemical reaction between the liquid phases of the eutectic lithium-lead (Li/sub 17/Pb/sub 83/) and water. The reactants and products were constrained within a closed reaction vessel, allowing the extent of reaction to be determined from the partial pressure of the hydrogen reaction product. The data from the tests showed that the extent of reaction did not depend upon the water temperature. The data also indicated that the extent of reaction passed through a maximum as the initial liquid metal temperature was varied from 350 to 500 C, and a model was developed to explain this behavior. 11 refs., 3 figs.
The use of absorbable polyglactin 910 mesh (Vicryl) is described in a case of Ewing's sarcoma of the pelvis. An operation was performed to hold the small bowel and colon out of the pelvis for a temporary period during which radical radiotherapy was delivered. The mesh allowed the temporary displacement of bowel and obviated bowel radiation morbidity. (author).
Although silicosis has been studied extensively, the mechanism is still not fully understood. Experiments do provide evidence that the actions of unique properties of silica surface on the cell membrane are the starting point of silicotic processes. This paper summarizes literature on chemical properties of silica surface, and the effect of particle size on silica toxicity. This paper also discusses the ways in which silica dusts are though to interact with the cell membrane, with emphasis on freshness, hydrogen bonding, and free-radical interactions.
The application of kinetic probes that allow one to determine relative reactivities of biologically relevant substrates with oxidizing intermediates in the Fenton reagent (H2O2 plus Fe2+ in acidic aqueous...Full Text Available
We demonstrate the nonuniqueness of the basic assumptions leading to spiral structure in self-propagating star formation models. Even in the case where star formation occurs purely spontaneously and does not propagate, we have generated spiral structure by adopting the radically different assumption where star formation is systematically inhibited.
The use of low rank coal leads to a reduction of the coke strength because of the reduction of the caking property of coking coal. The authors have tried to understand this mechanism by extracting and analyzing the caking component of low rank coal and coking coal. It was found that the caking component is decreased by radical attack from the low rank coal, and thus the caking property is reduced. 11 figs., 3 tabs.
There have been no radically new commercial bulk explosives since Atlas Powder Company's introduction of emulsions onto the market in 1968. But the effectiveness, safety and management of these familiar explosives is continuously being improved by the development of blast design techniques, explosives delivery and initiation systems, and monitoring methods. The author looks at developments in blasting technology and discusses experiences with Handibulk emulsion delivery systems.
DescriptionProgramme background Nanotechnology is the design and manufacture of substances typically between one and several hundred billionths of a metre in size. In this size range the properties of substances can change quite radically, offering potentially large socio-economic, health and environmental benefits. For example, nanofuel additives could help reduce emissions and particles from diesel engines. Nanoparticles may also be able to help remove persistent pollutants in soils and groundwaters. Th [continued...
The introduction of CT scan and, more recently, magnetic resonance imaging, has radically changed the diagnostic approach to tumors developed in the internal auditory canal and cerebellopontine angle. CT scan with intravenous injection visualizes tumors lying in the cerebellopontine angle. Magnetic resonance imaging, especially using gadolinium, is a very accurate means for diagnosing tumors of both the auditory canal and cerebellopontine angle.
Some applications of magnetic resonance in coal liquefaction research described briefly are: (1) investigation of the nature of carbon deposits on used coal-liquefaction catalysts, (2) determination of the fate of hydrogen during coal liquefaction, and (3) observation of transient free radicals during coal pyrolysis. The first two applications make use of cross-polarization /sup 13/C magnetic resonance combined with magic angle spinning, and the third application is an electron spin resonance study. (BLM)
Abstract High Post-Modernism with its understanding of the significance of the image anticipated the flattening of culture, first in advertising and the printed media, and more recently online. Sam Jacob of FAT speculates on architecture's relationship with the Internet, -a flatland of undifferentiated information-, and how Radical Post-Modernism might be best placed to resist the ubiquity of global culture while reanimating the social and cultural agenda of Modernism and Post-Modernism. Copyright 2011 John Wiley & Sons, Ltd.
Ultraviolet (UV) photoirradiation of Ag(I) compounds in the presence of an aqueous Triton X-100 solution has been exploited for the first time to prepare reproducible yellow silver hydrosol. The evolution of nanosized silver particles has been examined critically under the influence of different anions/ligands. Hence, time dependent evolution of silver hydrosol from different silver compounds in micelle via photochemical reduction is observed. Anions/ligands of precursor salts have been found to show profound influence (due to electron scavenging property, solubility, stability etc.) on the evolution route and efficiency of photochemical reduction of Ag(I) to Ag(O) in micelle and thereby classification of silver compounds becomes possible. Kinetic results reveal that the formation of silver particles proceeds via autocatalytic growth mechanism. The observed variation in rate constant values for the evolution of nanoparticles from different silver compounds have ...
A gas injection diesel engine was developed as an approaching measure to the diversification of fuel. Contrary to the usual low pressure gas application engine, this engine applies a so-called diffuse combustion method, in which high pressure (24.7Mpa) gas fuel is injected directly in the cylinder and is ignited and combusted by a little pilot fuel injected almost at the same time. The engine have following features. As a principle, it can attain the same heat efficiency and output rate as a diesel engine in any load range. It is excellent in responsibility to load fluctuation. There is no internal leakage of gas fuel to the scavenging chamber (the crank chamber) in the compression stroke. Not only a wide range of mixed combustion of gas fuel and heavy oil fuel, but also single combustion of heavy oil is possible. It is, therefore, drawing attention as an engine for an LNG ship and also for a power generation plant with the recent increasing demand of gas fuel ...
The adsorption capacity of radionuclides onto suspended sediment was experimented on each of the coastal seawater sampled around the Kori and the Wolsung nuclear power plant. During the experiment the quantity and size fraction of suspended sediment were adjusted and the seawater and sediment chemistry is approximated to the expected field condition. Because the sorption capacity depends on the specific minerals, ocean chemistry and radionuclide involved, it is necessary to analyze sediment mineralogy. Clay mineral is dominant in seabed mineral and suspended sediment as the result of x-ray diffraction. Radionuclide sorbed to silty-clay mineral can be rather transported to ocean than scavenged to seabed because of low quantity and fine grained suspended sediment in the coast around the Kori and the Wolsung. The result of adsorption examinations shows that {sup 139}Ce and {sup 51}Cr and {sup 110m}Ag are strongly sorbed to suspended particle, while {sup 137}Cs is less ...
The adsorption capacity of radionuclides onto suspended sediment was experimented on each of the coastal seawater sampled around the Kori and the Wolsung nuclear power plant. During the experiment the quantity and size fraction of suspended sediment were adjusted and the seawater and sediment chemistry is approximated to the expected field condition. Because the sorption capacity depends on the specific minerals, ocean chemistry and radionuclide involved, it is necessary to analyze sediment mineralogy. Clay mineral is dominant in seabed mineral and suspended sediment as the result of x-ray diffraction. Radionuclide sorbed to silty-clay mineral can be rather transported to ocean than scavenged to seabed because of low quantity and fine grained suspended sediment in the coast around the Kori and the Wolsung. The result of adsorption examinations shows that "1"3"9Ce and "5"1Cr and "1"1"0"mAg are strongly sorbed to suspended particle, while "1"3"7Cs is less sorbed and ...
Poly(methyl methacrylate), PMMA, Acrigel, a Brazilian polymer, is used in the manufacture of medical supplies sterelizable by ionizing radiation. However, when PMMA is gamma-irradiated it undergoes main chain scissions, which promote molecular degradation causing reduction in its mechanical properties. Therefore, radiolytic of PMMA is important for it to become commercially radiosterizable. In this work some commercial additives, originally used in photo-and thermo-oxidate stabilization of polymers, were tested. Only two additives, type HALS (Hindered Amine Light Stabilizer), denoted Scavenger, showed a good protective quality. The investigation of radiation-induced main scissions was carried out by viscosimetric method. The most effective additive, added to the polymer system at 0.3 w/w%, promotes a great molecular radioprotection of 93%. That means a reduction of G-value (scissions/100 eV) from 0.611 to 0.053. In addition, the glassy transition temperature (T{sub ...
Inductively coupled plasma etching of InGaP, AlInP and AlGaP in BI{sub 3} or BBr{sub 3} discharges was investigated as a function of source power, dc chuck bias and plasma composition. InGaP etches at the fastest rates ({gt}6000thinsp{Angstrom}thinspmin{sup {minus}1}) in both chemistries, followed by AlGaP. It is found that AlInP provides an excellent etch stop for the other two materials in both mixtures. The InGaP surface morphology improves with increasing BI{sub 3} or BBr{sub 3} content, and with increasing dc chuck bias. The etched features for this material are highly anisotropic. Etch selectivities for InGaP over SiO{sub 2} and SiN{sub x} of {ge}8 are obtained in both plasma chemistries, and there is no etch incubation time with either mixture, indicating that both can scavenge the native oxide on InGaP, AlGaP and AlInP. {copyright} {ital 1998 American Vacuum Society.}
Inductively coupled plasma etching of InGaP, AlInP and AlGaP in BI_3 or BBr_3 discharges was investigated as a function of source power, dc chuck bias and plasma composition. InGaP etches at the fastest rates (>6000 Angstrom min"-"1) in both chemistries, followed by AlGaP. It is found that AlInP provides an excellent etch stop for the other two materials in both mixtures. The InGaP surface morphology improves with increasing BI_3 or BBr_3 content, and with increasing dc chuck bias. The etched features for this material are highly anisotropic. Etch selectivities for InGaP over SiO_2 and SiN_x of #>=#8 are obtained in both plasma chemistries, and there is no etch incubation time with either mixture, indicating that both can scavenge the native oxide on InGaP, AlGaP and AlInP. copyright 1998 American Vacuum Society.
This project was conducted to evaluate novel approaches for removing radioactive strontium (Sr) and cesium (Cs) from the tank wastes. The bulk of the Sr removal research conducted as part of this project investigated adsorption of Sr onto a novel adsorbent known as iron-oxide-coated sand. The second major focus of the work was on the removal of cesium. Since the chemistries of strontium and cesium have little commonality, different materials (namely, cesium scavengers known as hexacyanoferrates, HCFs) were employed in these tests. This study bridged several scientific areas and yielded valuable knowledge for implementing new technological processes. The applicability of the results extends beyond the highly specialized application niches investigated experimentally to other issues of potential interest for EMSP programs (e.g., separation of chromium from a variety of wastes using IOCS, separation of Cs from neutral and acidic wastes with EC-controlled HCFs).
Semiclassical analysis of heavy ion induced transfer reactions are discussed for the quasielastic region. Some unique aspects of these reactions are shown, the variety of features which can be understood semiclassically is demonstrated, and some open problems are indicated. 28 refs., 16 figs. (LEW)
The shrinking core model is examined for gas-solid noncatalytic reactions with a self-inhibited rate form and it is shown that multiple reaction pathways are possible for solid particles reacted under identical conditions. The observed reaction rate can have up to two discontinuities (jumps) during reaction for particles of spherical and cylindrical shape. The geometric instability analysis reveals that the reaction interface is stable under a very limited set of conditions only for solid particles of slab geometry. For a sphere or cylinder at large Biot numbers the reaction interface is always potentially unstable. This model provides a plausible explanation for gas-solid reactions which exhibit erratic shrinking core behavior.
The effects of temperatures, durations of treatment, and derivations from spermatophores or spermaries on in vitro acrosome reaction of the spermatozoa in the Chinese mitten crab Eriocheir sinensis...Full Text Available
The chemical reaction between nitric acid and sodium chloride was investigated in onder to provide preliminary information for subsequent studies on the interaction between simulated Purex waste solution and salt. The reaction is characterized by the production of chlorine and nitrosyl chloride and can be considered to be the same as the aqua regia reaction. Within the limits of the conditions imposed by the projected field studies, the acid concentration and temperature are the two parameters which control the extent of the interaction. (auth)
Synthesis of silver nanoparticles based on a polyol process and variable frequency microwave (VFM) was investigated. Comparing to a thermal method, the reaction by VFM radiation was much faster. The effects of silver nitrate concentration, poly(N-vinylpyrrolidone) (PVP) concentration, reaction time and reaction temperature were studied. It was found that the higher concentration of silver nitrate, longer reaction time and higher temperature increased the particle size while the higher concentration of PVP decreased the particle size.
We have developed a set of modeled nuclear reaction cross sections for use in radiochemical diagnostics. Systematics for the input parameters required by the Hauser-Feshbach statistical model were developed and used to calculate neutron induced nuclear reaction cross sections for targets ranging from osmium (Z = 76) to gold (Z = 79). Of particular interest are the cross sections on Ir and Au including reactions on isomeric targets.
Microwaves improve the rate of many chemical reactions either interacting with the solvent, when the reaction is carried out in solution, or with the surface of a solid substrate where a suitable reagent is dispersed (dry chemistry). A few examples of chemical reactions positively affected by microwaves are described: particularly interesting are those concerning polymers and radio-pharmaceuticals.
During the period covered by this report research has been concerned with the study of photo-induced electron transfer reactions from porphyrins to acceptor molecules with time-resolved Electron Paramagnetic Resonance (EPR) methods. Excited-state electron transfer reactions are of importance from a fundamental point of view and in connection with applications in homogeneous and heterogeneous photosensitization, photopolymerization, and solar energy conversions. For this reason, the study of photo-induced electron transfer reactions is of considerable interest.
In this paper, steady-state isotopic transient kinetic analysis (SSITKA) is used to study two model reactions, CO oxidation and CO-NO reactions, on a typical formulation of a three-way auto-catalyst. Under steady-state conditions, abrupt switches in the isotopic composition of CO ("1"2C"1"6O/"1"3C"1"8O) were carried out to produce isotopic transients in both labeled reactants and products. Along with the determination of the average surface lifetimes and concentrations of reaction intermediates, an analysis of the transient responses along the carbon reaction pathway indicated that the distribution of active sites for the formation of CO_2 was bimodal for both reactions. Furthermore, relatively few surface sites contributed to the overall reaction rate.
W. E. B. Du Bois, one of the brightest lights in African American history, wrote a sparkling critique of the American social and economic system originally planned as part of the Bronze Booklets series, edited and published by Alain Locke and the Associates in Negro Folk Education. The piece was never published and has, until now, been lost to the annals of adult education history. Using historical evidence, the authors examine Du Bois's Basic American Negro Creed and the circumstances that led to its exclusion from the series. It is argued that the Creed was far too radical for the liberal minded Carnegie Corporation and its leaders who were only interested in accommodating adult education for Blacks through the AAAE funded Bronze Booklets. The exclusion of the Creed represents an example of repressive tolerance by the AAAE.
The authors present a search for excited and exotic muon states {mu}*, conducted using an integrated luminosity of 371 pb{sup -1} of data collected in p{bar p} collisions at {radical}s = 1.96 TeV at the Tevatron with the CDF II detector. They search for associated production of {mu}{mu}* followed by the decay {mu}* {yields} {mu}{gamma}, resulting in the {mu}{mu}{gamma} final state. They compare the data to model predictions as a function of the mass of the excited muon M{sub {mu}*}, the compositeness energy scale {Lambda}, and the gauge coupling factor f. No signal above the standard model expectation is observed in the {mu}{gamma} mass spectrum. In the contact interaction model, they exclude 107 < M{sub {mu}*} < 853 GeV/c{sup 2} for {Lambda} = M{sub {mu}*}; in the gauge-mediated model, they exclude 100 < M{sub {mu}*} < 410 GeV/c{sup 2} for f/{Lambda} = 10{sup -2} GeV{sup -1}. These 95% confidence level exclusions extend previous limits ...
Erectile dysfunction following radical prostatectomy remains a frequent problem despite the development of nerve-sparing techniques. This erectile dysfunction is believed to be neurogenic, enhanced by hypoxia-induced structural changes which result in additional veno-occlusive dysfunction. Recently, daily use of intracavernous vasoactive substances and oral use of PDE5-inhibitors have been clinically studied for treatment of postprostatectomy erectile dysfunction. Since these studies showed benefits of "penile rehabilitation therapy," these effects have been studied in a preclinical setting. We reviewed experimental literature on erectile tissue preserving and neuroregenerative treatment strategies, and found that preservation of the erectile tissue by the use of intracavernous nitric oxide donors or vasoactive substances, oral PDE5-inhibitors, and hyperbaric oxygen therapy improved erectile function by antifibrotic effects and preservation of smooth muscle. ...
A measurement of the t{bar t} production cross section at {radical}s = 1.96 TeV in the dilepton final states using a lepton+track selection and secondary vertex b-tagging is presented. One of the two leptons from the decay of the t{bar t} pair is allowed to be identified only as an isolated track to improve the selection efficiency. The result is combined with a measurement in the t{bar t} {yields} e{mu} final state. The measurements are based on 370 pb{sup -1} of data collected with the D0 experiment at the Tevatron collider. The preliminary cross section obtained in the combined lepton+track and e{mu} channel is: {sigma}{sub t{bar t}} = 8.6{sub -1.7}{sup +1.9}(stat) {+-} 1.1(syst) {+-} 0.6(lumi) pb.
The authors measure the dipion mass spectrum in X(3872) {yields} J/{psi}{pi}{sup +}{pi}{sup -} decays using 360 pb{sup -1} of {bar p}p collisions at {radical}s = 1.96 TeV collected with the CDF II detector. The spectrum is fit with predictions for odd C-parity ({sup 3}S{sub 1}, {sup 1}P{sub 1}, and {sup 3}D{sub J}) charmonia decaying to J/{psi}{pi}{sup +}{pi}{sup -}, as well as event C-parity states in which the pions are from {rho}{sup 0} decay. The latter case also encompasses exotic interpretations, such as a D{sup 0}{bar D}*{sup 0} molecule. Only the {sup 3}S{sub 1} and J/{psi} {rho} hypotheses are compatible with the data. Since {sup 3}S{sub 1} is untenable on other grounds, decay via J/{psi} {rho} is favored, which implies C = +1 for the X(3872). Models for different J/{psi}-{rho} angular momenta L are considered. Flexibility in the models, especially the introduction of {rho}-{omega} interference, enable good descriptions of the data for both L = 0 and 1.
This invention is a manufacturing method of a metal-hydrogen alkali battery cell consisting of a positive electrode of metal oxides, alkaline electrolyte solution and a separator containing an amide-radical, wherein the above treating solution is aqueous solution of KOH (or NaOH) which is heated at least at 40 centigrade and the separator is first immersiion-treated and then water-washed and dried. The amide-radical-containing separaator uses a nylon non-woven fabrics. Average molecular weight of nylon 66 is 12,000 - 20,000. In this invention, in order to improve the storage ability and the cycle characteristics which are caused by corrosion of a separator which takes place in the cell after its assembly, the separator is immersed in a hot alkali in order to obtain a non-woven fabric of nylon 66 consisting of alkali-stable high molecular weight portion, which is assembled into a battery. By this, the dissolving of the non-woven fabric and the ...
Penile rehabilitation has been an area of intense study and debate over the last decade. Interest in this topic was stimulated by the observation that erectile dysfunction remained a significant problem after radical prostatectomy despite meticulous nerve-sparing technique. Smooth muscle alterations and fibrotic changes in the penis were identified as the underlying causes of penile atrophy, veno-occlusive dysfunction, and Peyronie's-like changes that were observed after surgery. Initial observations that intracavernous injection therapies used on a regular basis postoperatively resulted in improvements in the return of spontaneous erectile function led to the development of penile rehabilitation protocols. Chronic dosing of oral type V phosphodiesterase inhibitors is now commonly used by urologists after radical prostatectomy despite a lack of convincing evidence from randomized, placebo-controlled clinical trials. Use of local therapies to ...
The EUROTRAC sub-project ''Tropospheric Ozone Research'' (TOR) follows a dual strategy: - Observation of the chemical processes contributing to the oxygen balance directly in the atmosphere; - Establishment of a validated data base for model calculations. Both tasks require simultaneous measurements of a wide range of chemical and meteorological components. In the case of the investigation of the chemical processes, it is also desirable to measure the free radicals directly involved in ozone production. In the project described, a measuring station was set up. For a period of two years and a half, continuous measurements were made of ozone and its chemical precursors (NO, NO_2, NO_y, VOC, CO), as well as other photooxidants (H_2O_2 and organic hydroperoxides, organic nitrates), the photolysis frequency of NO_2, and meteorological parameters (wind, temperature, moisture, aerosols). The station was located on the Schauinsland mountain in the southern Black Forest, at ...
The Green-Chasman lattice, which is the basis for both NSLS storage rings, was conceived with insertion devices in mind. Long, field-free straight sections were provided in the design. The electron optics were chosen so that these sections had zero dispersion and the effects of new magnetic structures placed in these regions would have minimal effect on the emittance of the electron beam. This design concept has been followed by all high-brightness rings which were built subsequent to the NSLS. The X-Ray Ring straight sections also have a very small vertical {beta} function, in addition to the zero dispersion. This was done to optimize the brightness of wiggler sources. There is a further benefit however. The {beta} function determines the beam size and divergence at a particular point in the storage ring lattice. The size is proportional to {radical}{beta} and the divergence is proportional to 1/{radical}{beta}. Thus the electron beam is very ...
The addition of paraquat (methyl viologen) to a growing culture of Escherichia coli K-12 led within 1 hr to a 10- to 20-fold increase in the level of endonuclease IV, a DNase for apurinic/apyrimidinic sites. The induction was blocked by chloramphenicol. Increases of 3-fold or more were also seen with plumbagin, menadione, and phenazine methosulfate. H_2O_2 produced no more than a 2-fold increase in endonuclease IV activity. The following agents had no significant effect: streptonigrin, nitrofurantoin, tert-butyl hydroperoxide, #gamma# rays, 260-nm UV radiation, methyl methanesulfonate, mitomycin C, and ascorbate. Paraquat, plumbagin, menadione, and phenazine methosulfate are known to generate superoxide radical anions via redox cycling in vivo. A mutant lacking superoxide dismutase was unusually sensitive to induction by paraquat. In addition, endonuclease IV could be induced by merely growing the mutant in pure O_2. The levels of endonuclease IV in uninduced or ...
A methodology for assessing the impact of subacute concentrations of organometallic agents on bioenergetic and oxidative damage processes in animals, cells and energy transducing subcellular organelles is being developed. Several of the assays are noninvasive and thus lend themselves to human tests. At the whole-animal level we utilize a treadmill chamber where physiological parameters of exercising animals are monitored. These include parameters of whole animals' work performance such as oxygen consumption, carbon dioxide evolution and endurance. Oxidative damage can be monitored in experiments by analyzing expired air of the animals for ethane and n-pentane. These alkanes correlate with lipid peroxidation in vivo. At the cellular and subcellular levels, respiratory activity, lipid peroxidation and free radical species are assayed. Respiratory activity is measured in muscle homogenates and isolated mitochondria using substrates which feed into different ...
New partial differential equations (PDEs) for the full order weak schemes of the Langevin simulations are formulated. They are solved recursively in full order series solutions with respect to {radical}(t) (the full order weak Taylor schemes). Arbitrariness involved in the solutions is analyzed and clarified in detail. Specific solutions within some orders are presented as examples of the weak Taylor schemes. These PDEs and their solutions will serve for further developments of efficient higher order Runge-Kutta-like schemes. The similar formulation is possible for the imaginary time Hamiltonian evolution kernels as well. (orig.). 9 refs.
Faced with a changing business emphasis, plus the need to reduce operations and maintenance costs in the North Sea, the Forties Field engineering partnership between BP and Brown and Root recognised the need to make radical changes in its organisational structure. An innovative change management programme was planned and executed inside 12 months with the purpose of right-sizing the Forties Operations Engineering team. Not only has the initiative succeeded in cutting costs by 40 per cent; it has also enhanced the quality of engineering support services supplied to the BP Forties platforms. (author)
Purpose: We present an update analysis of the multiinstitutional Ewing's sarcoma study CESS 86. Methods and Materials: From January 1986 through June 1991, 177 patients with localized Ewing's sarcoma of bone, aged 25 years or less, were recruited. Chemotherapy consisted of four 9-week courses of vincristine, actinomycin D, cyclophosphamide, and adriamycin (VACA) in low-risk tumors (extremity tumors =# 100 cm"3). Local therapy was an individual decision in each patient and was either radical surgery (amputation, wide resection) or resection plus postoperative irradiation with 45 Gy or definitive radiotherapy with 60 Gy (45 Gy plus boost). Irradiated patients were randomized concerning the type of fractionation in either conventional fractionation (once daily 1.8-2.0 Gy, break of chemotherapy) or hyperfractionated split-course irradiation simultaneously with the VACA/VAIA chemotherapy (twice daily 1.6 Gy, break of 12 days after 22.4 Gy and 44.8 Gy, total dose and ...
This article reviews antisocial personality disorder, psychopathy, and violence and develops a three factor model of personality traits. Then a discussion of related personality disorders precedes the development of a categorical two factor model of impulsive versus remorseless violence. A paradigm of proactive, medical, and school based early intervention and prevention is advocated as a useful addition to the reactive detention of criminal justice. Integration of psychological tests, neuroimaging, and genomic data in early childhood and school based intervention strategies to prevent the development of conduct disorder and attenuate criminal propensity inform this approach. PMID:20422651
This short communication aims to update the review of non-nitro radiation sensitizers (Shenoy and Singh 1985) and correct omissions. Work is mentioned and bibliography given for studied of cis-platinum, potassium permanganate, cobalt hexammine, sodium bromide, dimethylsulphoxide, zinc and copper ions, organic nitroxyl free radicals (TAN,TMPN and NPPN + PNAP), halogenated pyrimidines, organic and inorganic iodine containing compounds, diacetyl, acetone and acetophenone, rho-hydrobenzoic acid and its esters, pentobarbitone and secobarbitone, heparin and 9-anilinoacridines, dehydropiandosterone and paraquat. (U.K.).
Nano-materials in which a large fraction of atoms resides within a few atomic layers near the surface can be designed to have novel properties by manipulating their surface parameters. We show that the effective elastic constants of nano-porous/cellular materials can be made to exceed those of the parent materials provided the pore surface elastic parameters satisfy certain conditions. These stiff nano-porous materials herald a radical breakthrough in sandwich-type construction.
Nano-materials in which a large fraction of atoms resides within a few atomic layers near the surface can be designed to have novel properties by manipulating their surface parameters. We show that the effective elastic constants of nano-porous/cellular materials can be made to exceed those of the parent materials provided the pore surface elastic parameters satisfy certain conditions. These stiff nano-porous materials herald a radical breakthrough in sandwich-type construction.
Fractal dimensional analysis was employed to obtain a quantitative measure of the morphology of polymer networks formed by UV irradiation induced polymerization of photo-reactive mesogenic monomers dissolved in a liquid crystal host medium. The fractal dimensions obtained, may be interpreted by polymer network growth following a percolation-like model for monomer concentrations well below the solubility limit. On passing the solubility limit, the polymerization process changes from a (radical chain) solution polymerization to a dispersion polymerization, with fractal dimensions decreasing and suggesting a cluster-cluster aggregation process for monomer concentrations above the solubility limit, similar to the aggregation of colloidal particles.
We prove a cosmic no-hair theorem for Bianchi models in power-law inflation. Provided that the potential of an inflaton {phi} is exp({minus}{lambda}{kappa}{phi}) with 0{le}{lambda}{lt} {radical}2/3 , we find that the isotropic power-law solution is the unique attractor for any initially expanding Bianchi-type models except type IX. For Bianchi type IX, this conclusion is also true if the initial ratio of the vacuum energy to the maximum three-curvature is larger than one half.
The author presents a new technique for production of yellow cake with double precipitation, thus solving a series of problems for precipitating uranium with traditional double precipitation. The new technique can not only remove ferric ions and sulfate radicals but also make solid-liquid separation easy, utilize effectively the sulfuric acid produced in ferric ions precipitation process, and increase uranium concentration of leaching liquor. To take it as producing yellow cake will save investment, simplify operation, and cut down the consumption of raw materials and energies. It is more competitive than ion-exchange or solvent extraction in the process of extracting-purifying and preparing yellow cake.
Direct nuclear reactions are commonly understood in terms of distorted wave (DW) formalisms. In the case of a single nucleon knockout or transfer reaction the DW analysis provides a reasonable understanding of the observed data. On the other hand the predictions based on different available information inputs have been verified with the observations consistently. In the case of direct reactions involving nuclear clusters however, the DW predictions have been found to disagree with the observations in most cases. The outcome of these and other improvements in the intermediate energy nuclear phenomena involving direct reactions are highlighted. (author). 13 refs., 18 figs.
We summarize the predictions of different models for total {gamma}{gamma} cross-sections. The experimentally observed rise of {sigma}{sub {gamma}}{sub {gamma}} with s radical {sub {gamma}}{sub {gamma}}, faster than that for {sigma}{sub p-barp}, {sigma}{sub {gamma}}{sub p} is in agreement with the predictions of the Eikonalized Minijet Models as opposed to those of the Regge-Pomeron models. We then show that a measurement of {sigma}{sub {gamma}}{sub {gamma}} with an accuracy of < or approx. 8-9% (6-7%) is necessary to distinguish among different Regge-Pomeron type models (the different parameterisations of the EMM models) and a precision of < or approx. 20% is required to distinguish the predictions of the EMMs and of those models which treat 'photon like a proton', for the energy range 300< s radical{sub {gamma}}{sub {gamma}} <500 GeV. We further show that the difference in model predictions for ...
The water soluble, photolabile nitrene precursor, azidonaphthalene-2,7-disulfonic acid (ANDS) was encapsulated in small unilamellar, isoelectric (egg PC) or negatively charged (egg PC + dihexadecylphosphate) liposomes. The individual and combined effects of heme-proteins and UV irradiation on the fluorescence of these vesicles under aerobic conditions were studied. Consistent with the catalytic action of heme-proteins on lipid peroxidation and peroxide decomposition, addition of cytochrome c (positively charged) or catalase (negatively charged) to the vesicles elicited immediate formation of a fluorescence band at 470 nm, characteristic of Schiff bases that form from aldehyde byproducts of decomposing hydroperoxides. Ultraviolet irradiation of liposomes caused no significant changes in the fluorescence spectrum, in spite of the radiolysis of ANDS inside the vesicles with consequent formation of nitrene radicals. When isoelectric vesicles were irradiated with UV ...
Two electroactive polymeric arylene bisimides, namely poly[(4,7,10-trioxatrideca-1,13-diyl)-(1,4,5,8-naphthalenetetracarboxylic bisimide-N,N'-diyl)] and its perylene analogue - poly[(4,7,10-trioxatrideca-1,13-diyl)-(3,4,9,10-perylenetetracarboxylic bisimide-N,N'-diyl)] have been synthesized and studied by cyclic voltammetry, UV-vis-NIR as well as Raman spectroeletrochemistry. Contrary to low molecular weight arylene bisimides, which show a clear two electron, double-step electrochemical reduction (neutral form to radical anion and from radical anion to dianion), in the synthesized polymers multielectron transfers are observed, accompanied with a strong electrochromic effect. However, as probed by cyclic voltammetry, their first reduction step is retarded and covers a wider potential range. We attribute this effect to macromolecular nature of the compounds being reduced and their structural inhomogeneity caused by ?-stacking induced ...
The evaluation of radiotherapy and surgery as exclusive local treatment in comparably selected subgroups of patients with Ewing's sarcoma on the basis of the CESS 86-data. In the German multicenter Ewing's sarcoma study CESS 86, treatment consisted for four 9-week-courses of VACA- or VAIA-chemotherapy plus local therapy. VACA (vincristine, actinomycin D, cyclophosphamide, adriamycin) was given in low-risk extremity tumors with a tumor volume below 100 cm"3. Highrisk patients with central lesions or a tumor volume >100 m"3 received VAIA (ifosfamide instead of cyclophosphamide). Local therapy started after one complete chemotherapy course in week 10. Based on an individual decision in each patient, local therapy was either radical surgery or resection plus postoperative irradiation with 45 Gy or definitive radiotherapy with 60 Gy. Because of poor results with radiotherapy in a preceeding study, it was intended to restrict irradiation to patients with small ...
When clinoptilolite is immobilized in cement-based composites, a series of reactions occur, leading to release of Cs. These reactions occur in three overlapping stages: a rapid ion exchange, followed by a somewhat slower reaction between clinoptilolite and principally the Ca(OH)_2 component of cement, and, in the longer term, slower reactions with C-S-H leading either to formation of low-lime C-S-H at temperatures below 100"0C or 11 A (1.1 nm) tobermorite at higher temperatures. Kinetic data are presented to evaluate the rate of physical consumption of the zeolites at 70 and 150"0C. Reactions occurring above 100"0C appear to result in the development of extensive microcracking of cement-zeolite composites containing 50% zeolite.
The metal parts of cardiac valve prostheses cause reactions in the surrounding tissues of the heart. In some dogs rather abnormal reactions were found, and were attributed to corrosion of the stainless...Full Text Available
This book examines some of the basic principles behind chemical reaction kinetics. Topics considered include the classical trajectory approach to reactive scattering; periodic orbits and theory of reactive scattering; and semiclassical reactive scattering.
The measurement of polarization in backward scattering for the reactions $\\pi^{+} p \\rightarrow p \\pi^{+},K^{+} p \\rightarrow p K^{+}$ and $\\;\\pi^{+} p \\rightarrow \\Sigma^{+} K^{+}$
This report discusses the following topics: Fusion-fission in light nuclear systems; High-resolution Q-value measurement for the {sup 24}Mg+{sup 24}Mg reaction; Heavy-ion reactions and limits to fusion; and Hybrid MWPC-Bragg curve detector development.
The gas-solid reaction and breakthrough curves in the fixed-bed reactor are of great importance, and being influenced by a number of factors makes the prediction of these factors a difficult problem. In this study, the reaction rate between solid sorbents and hydrogen chloride gas at high temperature was first investigated. On the basis of a fixed-bed reactor, the experimental results were analyzed by the shrinking core model of diffusion and surface chemical reaction control. The results showed that reaction rates of two sorbents with hydrogen chloride gas were controlled by the combination of the surface chemical reaction and diffusion of product layers, and the reaction rates nearly keep constant within 15 h of the initial reaction period and then decrease gradually. The results of the breakthrough curves show that solid sorbents in the ...
The A(..pi../sup +/,/sup 3/He)B reaction near threshold is studied in a model where the pion is absorbed by an /sup 4/He constituent of the target nucleus. The predictions of this model using harmonic oscillator cluster wave functions agree semi-quantitatively with the experimental data on the inverse reaction.
Phenothiazine-N-carbonyl chloride inactivated chymotrypsin and trypsin by means of a 1:1 stoicheiometric reaction. Its reaction with chymotrypsin was 29 times as fast as that with...Full Text Available
A Pd(0)-catalyzed intramolecular Heck-type reaction of oxime ether has been developed, providing convenient access to heterocyclic oximes. PMID:21964259
The measured result of charged multiplicity in cosmic-ray proton induced nuclear reaction from Chinese satellite emulsion is reported. The correlation of shower and heavy particles is discussed and compared with p-emulsion interactions.
Chemical reactions in living cells are under strict enzyme control and conform to a tightly regulated metabolic program. However, uncontrolled and potentially deleterious endogenous reactions occur,...Full Text Available
Heterogeneous gasless reactive systems, including high-energy density metal-nonmetal compositions, have seen increasing study due to their various applications. However, owing to their high reaction temperature, short reaction time, and small scale of heterogeneity, investigation of their reaction mechanisms and kinetics is very difficult. In this study, microstructural changes and the kinetics of product layer growth in the W-Si system was investigated using a high-speed x-ray phase-contrast imaging technique. Using the Advanced Photon Source of Argonne National Laboratory, this method allowed direct imaging of irreversible reactions in the W-Si reactive system at frame rates up to 36 000 frames per second with 4 {mu}s exposure and spatial resolution of 10 {mu}m. Details of the Si melt and reactions between W and Si, that are unable to be viewed with visible-light imaging, were ...
Heterogeneous gasless reactive systems, including high-energy density metal-nonmetal compositions, have seen increasing study due to their various applications. However, owing to their high reaction temperature, short reaction time, and small scale of heterogeneity, investigation of their reaction mechanisms and kinetics is very difficult. In this study, microstructural changes and the kinetics of product layer growth in the W-Si system was investigated using a high-speed x-ray phase-contrast imaging technique. Using the Advanced Photon Source of Argonne National Laboratory, this method allowed direct imaging of irreversible reactions in the W-Si reactive system at frame rates up to 36 000 frames per second with 4 #mu#s exposure and spatial resolution of 10 #mu#m. Details of the Si melt and reactions between W and Si, that are unable to be viewed with visible-light imaging, were ...
ObjectiveTo assess the efficacy and safety of low dose adrenaline injected subcutaneously to prevent acute adverse reactions to polyspecific antivenom serum in patients admitted...Full Text Available
To examine the association of human papillomavirus (HPV) infection with anal squamous cell carcinoma, the authors applied the highly sensitive polymerase chain reaction (PCR) and in situ hybridization...Full Text Available
The high-energy reaction cross sections of Li and Be isotopes are calculated using a simplified Glauber model and densities constrained by the empirical binding energies. We find excellent agreement with experiment, reproducing the large increase for the most neutron-rich nuclei.
IntroductionRadiotherapy outcomes might be further improved by a greater understanding of the individual variations in normal tissue reactions that determine tolerance. Most published...Full Text Available
A sensitive assay based on the polymerase chain reaction for the detection of Ockelbo virus RNA was developed. Two primer pairs from the gene coding for the E2 glycoprotein were chosen. By use of a...Full Text Available
AIMS: To evaluate the sensitivity of the Roche Cobas, Roche Amplicor plate kit, ligase chain reaction (LCR), and an in house polymerase chain reaction (PCR) by titration of purified elementary bodies...Full Text Available
A high-throughput assay for enzyme activity has been developed that is reaction independent. In this assay, a small-molecule yeast three-hybrid system is used to link enzyme catalysis to transcription...Full Text Available
Anaerobic reactions of Rhus vernicifera laccase and its type-2 copper-depleted derivatives with hexacyanoferrate(II) were investigated by absorption and e.s.r. spectroscopy. When native laccase was...Full Text Available
Disclosed are additives for hydrocarbon fuels which are the reaction products of a polyamine and an alkyl ester of acrylic or alkyl acrylic acid. A preferred composition is a mixture of the reaction product and oxygenated or non-oxygenated mono- or polyamines.
One hundred and seventy-nine patients completed a questionnaire focusing on adverse reactions to dental local anesthetics as manifested by 16 signs and symptoms. Twenty-six percent of the participants...Full Text Available
'The interactions of carbon tetrachloride with strongly basic oxides and hydroxides have been studied by several techniques in order to understand the surface reactions and the subsequent bulk reactions that result in the destruction of the chlorinated hydrocarbon. Emphasis has been placed on understanding the surface phases, as well as the bulk phases, that are present during these transformations. As a result of the study with barium oxide, a reaction cycle has been demonstrated that may have practical significance in the removal of chlorinated hydrocarbons.'
The esterification reaction of a long-chain fatty acid and a fatty alcohol catalyzed by sugar ester-modified lipases in organic media was studied. The reaction activity was improved when the lipases were modified with sugar esters. Among four kinds of sugar esters and six kinds of lipases, lipase CES modified with sugar ester SE-7 showed the highest reaction activity. The pH, solvent and temperature on the reaction activity of SE-7 modified lipase CES were also studied. PMID:12142919
The cold fusion reactions leading to superheavy elements with Z=104-116 has been discussed in our model recently [5]. Presently we shortly discuss our model and extend our consideration to fusion reactions ("8"6Kr, "8"7Rb, "8"8Sr)+"2"0"8Pb and "8"6Kr+"2"0"9Bi leading to elements with Z=118-120. The available experimental cross-section data for the reactions are well described.
Efforts has been made to specify surface ozone production in photochemical reaction due to the high concentration of NO_x and photon rays. The secondary reactions has been considered via optical measurements using actinometry and pyranometry which was followed for photochemical reactions at high temperature and because of air pollutants due to the traffic load and because of the inversion in certain days. The concentration of surface ozone which was measured in Tehran city center was in the range of 24- 45 ppb in 1991-1992 and a higher concentration of 45-65 ppb was measured in 1999-2000. This high surface ozone concentration could cause a severe damage to biota, fauna and human health.
A fuel composition comprising a liquid hydrocarbon fuel and a detergent amount of the product of reaction between a polyamine and a stearic acid is described.
A black-disc model combined with accurate matter densities has been used for an investigation of reaction cross sections for {sup 3}He, {sup 4}He and {sup 12}C projectiles. A simple relation is derived between the energy dependence of the reaction cross sections and the strength of the nucleon-nucleon interaction. A comparison is also made of the reaction cross sections for {sup 3}He and {sup 4}He for six different nuclei {sup 12}C, {sup 16}O, {sup 40}Ca, {sup 58,60}Ni and {sup 208}Pb.
The development of detailed chemical kinetic reaction mechanisms for analysis of autoignition and knocking of hydrocarbon fuels is described. In particular, kinetic processes of concern for the oxidation of complex hydrocarbon fuel molecules are emphasized. The wide ranges of temperature and pressure which are encountered by end gases in automobile engine combustion chambers result in extreme demands on reaction mechanisms which are intended to describe knocking conditions and predict rates of combustion and ignition. The reactions and chemical species which are most important in each temperature and pressure regime are discussed, and the validation of these reaction mechanisms through comparison with idealized experimental results is described. 53 refs., 8 figs., 5 tabs.
Nucleosynthesis and energy production in stellar environments depend critically on nuclear reaction cross sections. Reactions induced by alpha particles are important in the helium burning stage of stars, novae, and supernovae events. They involve light to medium weight nuclei up to about Z=32, and center-of-mass energies up to about 20 MeV. We are working on a project to compile and evaluate cross section data for alpha-induced reactions. These data will eventually be used to derive #alpha#-nucleus potential parameters. (author)
Although low-energy ion radiation has been proven to have a wide range of biological effects and led to fruitful achievements as a new mutagenic source for genetic modification, there still exist some disputes about its mutagenic mechanisms because of its short-penetrating property. In present research, Arabidopsis thaliana transgenic for GUS recombination substrate was used to evaluate the genomic instability induced by irradiations of alpha particle (3.3MeV) and Low-energy-Argon ion (30 KeV). A pronounced effects of alpha particle irradiation to Arabidopsis thaliana seedlings and Argon ion irradiation to seeds on the somatic homologous recombination frequency (sHRF) were reported. The sHRFs increased 1.88-fold and 2.42-fold, respectively, which indicated that the short-penetrating radiation could effectively induce the plant genomic instability in either dry seeds or seedlings with active metabolism. The local alpha particle irradiation of root was performed. Result exhibited ...
Anthropogenic nitrogen (N) deposition affects many natural processes, including forest litter decomposition. Saprotrophic fungi are the only organisms capable of completely decomposing lignocellulosic (woody) litter in temperate ecosystems, and therefore the responses of fungi to N deposition are critical in understanding the effects of global change on the forest carbon cycle. Plant litter decomposition under elevated N has been intensively studied, with varying results. The complexity of forest floor biota and variability in litter quality have obscured N-elevation effects on decomposers. Field experiments often utilize standardized substrates and N-levels, but few studies have controlled the decay organisms. Decomposition of beech (Fagus sylvatica) blocks inoculated with two cord-forming basidiomycete fungi, Hypholoma fasciculare and Phanerochaete velutina, was compared experimentally under realistic levels of simulated N deposition at Wytham Wood, Oxfordshire, UK. Mass loss was ...
This paper describes a practical knowledge on gas engine performance and combustion characteristics which are required by experimental studies for two types of developed gas burning engines, i. e. a spark ignited gas engine and a dual fuel engine, and also introduces their practical use and application. As for dual fuel engine performance, a manifold air pressure of about 27% was decreased, a scavenging ratio of 23% reduced and an exhaust temperature at the turbine inlet on 14% was increased at the gas engine operation under the mean effective cylinder pressure of 1.22 MPa in comparison with the diesel operation. Furthemore, empirical data on the effect of excess air ration on the engine performance and combustion characteristics, a risk of knocking during changing over on the dual fuel engine operation, and the rated output in case of using alternate fuel gas were reported. Two spark ignited gas engines with a rated output of 250 PS each using town gas for the ...
Photoinduced charge separation reactions form the basis for energy storage processes in both natural and artificial photosynthesis. Moreover, rapid reversible photoinduced electron transfer reactions are a class of photophysical phenomena that can be exploited to develop schemes for optical switching. Examples from each of these fields are discussed.
A method for the calculation of excitation functions and isomer ratios, for shape isomers, in heavy ion induced reactions is proposed. The calculated values of excitation functions and isomer ratios agree very well with the experimental values for the reaction /sup 238/U(/sup 11/B, alpha 3n)/sup 242/Am. (auth)
This book examines some of the basic principles behind chemical reactions kinetics. Topics considered include ab initio determination of potential energy for chemical reactions; semi-empirical potential energy surfaces; general theory of reactive scattering: different equation approach; and integral equation approach to reactive scattering.
Using the PMR method the interaction of zirconium and hafnium tetrachlorides with tri.tet.butylphenyl ester of 1,2- naphthoquinonediazide (2)-5-sulfonic acid is studied. The formation of MCl/sub 4/xNQD complexes is established, the equilibrium constants and thermodynamic parameters of complexing reaction are determined. The presence of rapid ligand exchange, proceeding according to associative mechanism, is detected. The rate constants and activation energies of the exchange reaction are calculated.
Using the PMR method the interaction of zirconium and hafnium tetrachlorides with tri.tet.butylphenyl ester of 1,2- naphthoquinonediazide (2)-5-sulfonic acid is studied. The formation of MCl_4xNQD complexes is established, the equilibrium constants and thermodynamic parameters of complexing reaction are determined. The presence of rapid ligand exchange, proceeding according to associative mechanism, is detected. The rate constants and activation energies of the exchange reaction are calculated.
The review is devoted to the use of ionic liquids as solvents, immobilized organocatalysts and reagents in reactions involving carbon acids and 1,3-dipoles, which are widely used to prepare practically valuable organic compounds of various classes. The characteristic features of processes in the presence of ionic liquids, the effects of the structure of cations and anions on the regio-, stereo- and enantioselectivities of reactions and methods of recovery of ionic liquids are considered.
The kinetics of the reaction of carbon dioxide in MDEA solutions were studied both experimentally and theoretically. It is concluded that MDEA acts as a homogeneous catalyst for CO/sub 2/ hydrolysis, and as a result the rate of absorption in aqueous MDEA solutions is significantly larger than one would calculate by simply taking into account the alkalinity of the reaction. A possible zwitterion mechanism is proposed for this reaction. The minor effect of ionic strength were also studied with the presence of other ions. 19 references, 6 figures.
The principle of operation of shaft furnaces is explained and demonstrated in four practical examples. The conditions and parameters determining coke conversion in the combustion zone and in the Boudouard reaction range are described. The combustion process is treated as a whole while the reduction process is discussed separately for the blast furnace, the cupola furnace, and the shaft furnace. The possibilities describing the Boudouard reaction as a function of the temperature level are discussed and consequences are derived for further experimental and theoretical studies.
Unsymmetric diaryl alkynes were synthesized from the palladium-catalyzed decarboxylative coupling of aryl halides and propiolic acid using a continuous flow reaction system. This flow chemistry system continuously gave the desired products in moderate to good yields, and produced less byproduct than was formed in the batch reaction.
The reactions of alpha particles on natural abundance chromium have been studied between 40 and 110 MeV, in order to produce "5"2Fe for medical use. The yield of the reaction "5"2Cr(#alpha#,4n)"5"2Fe for Esub(#alpha#) = 85 #-># 53 MeV is only 30 #mu#Ci/#mu#Ah. (orig.).
The catalytic properties of molybdena-alumina catalysts reduced in hydrogen were studied in the function of the reduction temperature, i.e. in the function of the extent of reduction. The deuterium exchange reaction of benzene was used as model catalytic reaction. It was concluded that the reaction rate constant and the multiplicity factor decreased with the extent of reduction parallel with the change in the extent of dehydroxylation of the catalysts. (orig.)
An 'electron-bridge' mechanism of nuclear reaction in an atom or ion by ultra-intense laser fields is presented. A preliminary estimate of the intensity dependence of the rate of disintegration reaction of deuteron nucleus in deuterium atom is made for 800 nm laser fields. For intensities below 5x1021 W/cm2, the rate of disintegration by the 'electron-bridge' mechanism is found to be small, but it rises sharply and becomes large already for ?1022 W/cm2.
The production of ozone in a negative corona discharge fed by carbon dioxide with embedded traces of oxygen and water has been studied. The presence of traces of oxygen in both pure and dry CO_2 leads to an increase in nascent ozone concentrations. In contrast, traces of water vapour (0-800 ppm) are shown to rapidly suppress ozone concentrations with the largest decreases being observed at lowest gas pressures in the discharge (300 Torr). The presence of water vapour did not considerably affect the electrical properties of negative dc corona suggesting that a chemical process is responsible for the ozone loss. We have shown that the addition of water up to a concentration of 1500 ppm has only a marginal effect on the processes of ozone formation but the catalytic cycle of ozone destruction involving OH radicals can be the reason for observed decrease in the total ozone concentration with increasing water concentration.
In the first paper of this series devoted to a structural analysis of a binary metallic glass model, we study a Pd/sub 80/Si/sub 20/ sample obtained by numerical relaxation. We discuss the reproducibility of the method and make a comparison with the experimental interference functions. Then we undertake a microscopic structural analysis from several point of view: we first study the number of neighbours of each type for each type of atoms; secondly, we analyse the structure by means of the radical plane method; at last, we show that it is possible to generalize the five fundamental characteristic units introduced by Bernal, so that we can define the environment of any Si atom without any ambiguity. All these methods reveal a certain tendency towards a prismatic environment for the metalloids.
Women treated of localised stages of cervix cancer have a very good prognosis. But do health care professionals have a tendency to underestimate the potential need for rehabilitation of this group? To be able to answer this question this study aimed to develop knowledge concerning these women's own perception of their health during a long period after surgical cancer treatment. A total of 398 women who underwent radical hysterectomy in the period from the 1 January 1983 to 31 December 2000 participated in the study at Aarhus University Hospital, Skejby in Denmark 2001-2003. All patients initially filled in an internally validated questionnaire. Subsequently a sample of 100 women filled in the questionnaires Short Form -36 and Sense of Coherence to evaluate their self-reported health. Analy...
Abstract Male infertility continues to be a clinical challenge of increasing significance. While male factors such as decreased semen quality are responsible for 25% of all infertility issues, the etiology of suboptimal semen quality is poorly understood. Many physiological, environmental, and genetic factors have been implicated, including oxidative stress. Oxidative stress is induced by reactive oxygen species (ROS), or free radicals, and although ROS are required for critical aspects of sperm function, excessive levels of ROS can negatively impact sperm quality. The origin of ROS generation, and the etiologies of increased ROS in men with suboptimal sperm quality have only recently been elucidated, offering multiple targets for potential therapy. Here, we present a critical review of th...
uv irradiation (365 nm) of air-saturated methanol solutions of 20 drugs absorbing in the 300 to 400 nm region gave rise to oxygen uptake, as determined with a polarographic oxygen electrode. The drugs were tested for photosensitizing capability by either a Type I (free radical) or a Type II (single molecular oxygen) mechanism. This testing was done by the inclusion of either acrylamide or 2,5-dimethylfuran in the irradiated drug solution, with observation of the subsequent polymerization or oxidation, respectively. Phenothiazine and thiazide derivatives appear capable of photosensitization by both mechanisms; promethazine, trifluoperazine, and furosemide show relatively high reactivity. Diazepam (weak), hexachlorophene, aminacrine, pyrilamine, tetracycline, demeclocyline, quinine, and anthracene (strong) react only by a Type II mechanism, with a photosensitizing efficiency increasing in the order given. A correlation appears to exist with reports of in vivo ...
The mutual influence between the PP/PS polymer blend components during UV photodegradation was studied. Polypropylene (PP) and polystyrene (PS) have different photodegradation mechanisms, due to the larger UV absorption of polystyrene and formation of more stable tertiary carbon radicals. To compare the stabilities the kinetics of carbonyl formation was measured in different blend compositions. The results show that polystyrene presented a faster carbonyl formation than polypropylene, while the blends display faster kinetics than the isolated components. The kinetics of carbonyl formation of the blends was a function of polypropylene content. This result is unexpected if one considers the behaviour of each component alone. The kinetics and mechanism of UV degradation can be only explained ...
A three-dimensional, continuous-energy, coupled neutron-gamma Monte Carlo model of the advanced neutron source (ANS) final preconceptual reference core design has been developed using MCNP Version 3b. This model contains the reactor core with control rods, the heavy-water reflector tank with shutdown rods and representative beam tubes, and the outer light-water poor. Eighty homogenized fuel zones per fuel element are used to represent the radical and axial {sup 235}U fuel grading. This model is the most sophisticated, physically accurate reactor physics model of the ANS currently available. The purpose of this summary is to demonstrate the MCNP methods and applications for the ANS.
Subcutaneous involvement frequently occurs in maxillary sinus carcinoma. Radical resection does not include removal of the skin at risk. In standard postoperative wedge-pair treatment plans, the surface dose is dependent upon beam weighting, beam energy, and patient contour. Thermoluminescent dosimetry (TLD) measurements were performed to evaluate the surface dose of patients undergoing postoperative irradiation of maxillary sinus carcinoma following primary resection. When 60 Gy was delivered to isocenter with a 45 degrees wedge pair and 6 MV photons with 1 cm bolus, the subcutaneous tissues at risk received {approximately} 30 Gy. Based upon presented TLD measurements, supplemental electron beam therapy to the subcutaneous tissues if primarily involved should be considered.
New market based approaches are becoming increasingly important as instruments of environmental policy. The two main market approaches, i.e., transferable pollution permits (experimented in America), and 'green' energy surcharges (European philosophy), are described and discussed. An analysis of information on their state of implementation shows that, in the case of the former method, the greatest sources of difficulty arise in the determination of acceptable ceiling levels of emissions, in the distribution of permits among the various polluting firms, and in the legality of granting rights to pollute. Instead, the European experience has evidenced that energy surcharges motivated by environmental policy cannot have an appreciable positive impact on consumers or the economic system in general unless they are accompanied by well defined measures geared towards the promotion or creation of alternative solutions such as to stimulate radical change in ...
A 46-year-old man was referred to us after he presented to his local physician complaining of difficulty eating. Upper gastrointestinal endoscopy revealed a tumor at the esophagogastric junction (EGJ), and moderately differentiated adenocarcinoma was diagnosed from the biopsy findings. Computed tomography (CT) showed apparent enlargement of the pretracheal lymph nodes, the lymph nodes around the bilateral recurrent laryngeal nerves, and the lower thoracic paraesophageal lymph nodes, confirming metastasis. Since the disease was far advanced esophagogastric cancer with marked lymph node metastases throughout the mediastinum, curative resection would have been unlikely. Thus, he was commenced on systemic chemotherapy with cisplatin (90 mg/body, day 8) + S-1 (120 mg/body/day, given for 3 weeks...
We investigate how, and to what extent, morphological complexity of the language influences text classification using support vector machines (SVM). The Croatian-English parallel corpus provides the basis for direct comparison of two languages of radically different morphological complexity. We quantified, compared, and statistically tested the effects of morphological normalisation on SVM classifier performance based on a series of parallel experiments on both languages, carried over a large scale of different feature subset sizes obtained by different feature selection methods, and applying different levels of morphological normalisation. We also quantified the trade-off between feature space size and performance for different levels of morphological normalisation, and compared the resul...
An organic inhibitor for acid corrosion inhibition is described. The inhibitor is a condensation product of a mixture of diethyl- and dibutyl-thiourea with hexamethylenetatramine. This condensation product is preferably made by reacting a mixture of diethyl- and dibutyl-thiourea, in a weight ratio of from 1:5 to 5:1, with 0.1 to 1 mole of hexamethylene tetramine per mole of the thiourea mixture, at temperatures of from 100 to 150 C. It is possible to modify this by using other organic thiourea derivatives containing organic radicals (aliphatic or aromatic) having up to 10 carbon atoms, for example, ditoluyl-thiourea, in addition to the mixture of diethyl- and dibutyl-thiourea, but the amount by weight of these other derivatives must not exceed 20% of the diethyl-dibutyl-thiourea mixture. The advantages of the inhibitor are observed mainly when it is used in hydrofluoric acid solutions. 6 claims.
Childhood cancer survivors at highest risk of developing a secondary malignancy are those with hereditary retinoblastoma. The majority of such secondary cancers will be sarcomas, most commonly of bone. One-third of these occur outside a typical radiation field, commonly in an extremity. Bone sarcoma is also the most commonly reported secondary cancer to develop among survivors of Ewing's sarcoma. In this group, radiation doses greater than 60 Gy as well as alkylating agent chemotherapy have been identified as contributors to the increased risk. The prognosis for patients with a secondary sarcoma has been poor, with few cures reported to date. However, an aggressive, combined modality approach, including radical resection, postoperative radiation, and adjuvant chemotherapy, may improve the survival rate.
The paper proposes a concept of power driver for industrial thermonuclear reactor based on inertial thermonuclear synthesis (ITS). The circuit is based on the application of free electron laser (FEL) as a energy source for thermonuclear target compression which becomes feasible due to the application of a radically new circuit of FEL-amplifier. In the project under consideration the FEL-based laser system operates on the wave length of 0.5 micrometer. The full energy of laser radiation equals 1 MJ. This energy is delivered to the target in the pulse whose length is controlled within the range of 0.1-2 ns. The laser system brightness is 4 x 10"2"2 W cm"-"2. The FEL operating pulse repetition frequency is 40 Hz, full efficiency of electricity conversion into the energy of optical radiation is 11%. 9 refs., 3 figs., 2 tabs.
This study uses an electronic commerce (E-commerce) innovation model to analyze the differences in technological knowledge, business model, and dynamic capability aspects used in Internet-enabled commerce (I-commerce) versus mobile commerce (M-commerce) versus ubiquitous commerce (U-commerce). The results indicate that the innovation from I-commerce to M-commerce is radical, leading to drastic changes in the business model. However, from M-commerce to U-commerce, disruptive changes occur in both technological and business model dimensions. A set of critical dynamic capabilities for each innovation is identified. These results provide great insight for practitioners and scholars for enhancing their understanding of E-commerce innovation, and provide guidelines to help practitioners adapt fr...
Ionizing radiation has been used to treat poultry to remove harmful microorganisms, mainly Salmonella, which contaminates chicken, goose and other fresh and frozen poultry. This microorganism is sensitive to low dose radiation. Thus, irradiating these foods with doses between 1 to 7 kGy results in a large reduction of bacteria. Since it is necessary to determine whether irradiation has occurred and to what extend, this work studied the signal produced by ionizing radiation within the hard crystalline matrix of chicken`s bone to establish a control method. Chicken`s drumsticks were irradiated and bones separated from flesh were lyophilized and milled. ESR spectrum was then obtained. The ESR signal increased linearly with dose over the range 0.25 to 8.0 kGy. Free radicals evaluated during 30 days after irradiation showed stable in this period. (Author).
R-matrix analyses of neutron-induced reactions for many of the lightest p-shell nuclei are difficult due to a lack of distinct resonance structure in the reaction cross sections. Initial values for the required R-matrix parameters, E,sub(lambda) and ..gamma..sub(lambdac) for states in the compound system, can be obtained from shell model calculations. In the present work, the results of recent shell model calculations for the lithium isotopes have been used in R-matrix analyses of /sup 6/Li+n and /sup 7/Li+n reactions for E sub(n) < 8 MeV. Consequences of the shell model predictions for the level structure of /sup 7/Li and /sup 8/Li on the /sup 6/Li+n and /sup 7/Li+n reaction mechanisms and cross sections are discussed.
This experiment is carried out in the series of the investigation on the damage mechanism of carbon steel. In this paper, the damage situation is considered by structure observations. The test were carried out in 600degC-1200degC temperature range, in blowing an argon gas. The reagents are Na{sub 2}O, Na{sub 2}O{sub 2} and NaOH. From structure observations, the holes are observed on the surface of iron-base material in some test conditions. This result is indicated that the selective reaction occurs. The selective reaction is more obvious as the time exposed to the high temperature is longer. It is considered that the selective reaction occurs after the chemical reaction between iron-base material and sodium compound. The areas, in which Mn-concentration is higher, are observed in products on the surface of specimen. (author)
In the course of designing a catalytic porous membrane reactor for experimental studies, both inside and outside of the non-reaction zones as well as the two ends of the membrane need to be completely sealed to ensure that there is no flow across the membrane in the non-reaction zone. Experiments show that up to 50% of the total flow across the membrane may be contributed by the axial flow along the wall of the non-reaction zones if only one side of the membrane is sealed. Another problem that cannot be solved by sealing is the capillary flow of the catalyst along the tube wall into the non-reaction zones when the catalyst is doped on the membrane. One of the best ways to avoid this axial flow of catalyst would be to use non-porous tubes in the non-reaction zones and join them with the porous membrane tube. In doing so, the cost of the membrane reactor could be reduced simply ...
In terms of the reduced potential energy barrier ? = ?uTS/kT, the rate coefficients for chemical reactions are usually expressed as proportional to e-?. The coupling between vibrational modes of the medium to the reaction coordinate leads to a proportionality of the regularized gamma function of Euler Q(a,?) = ?(a,?)/?(a), with a being the number of modes coupled to the reaction coordinate. In this work, the experimental rate coefficients at various temperatures for several chemical reactions were fitted to the theoretical expression in terms of Q(a,?) to determine the extent of its validity and generality. The new expression affords lower deviations from the experimental points in 29 cases out of 38 and it accounts for the curvature in the logarithmic plots of rate coefficients versus inverse temperature. In the absence of tunneling, conventional theories predict the curvature of these plots to be ...
Nuclear astrophysics seeks for a possible explanation of the observed abundance distribution of various elements and their isotopes in the universe. Most of the relevant nuclear reactions take place in thermally equilibrium environments with bare nuclei, rather than accelerated and head-on colliding situations with low ionisation states of reactant atoms and molecules that are emulated in the laboratories. Moreover, the temperature of the astrophysical environments is quite often low compared to the centre-of-mass energy of the projectile nuclides, that is required for the reaction to be meaningfully investigated in the laboratory. Therefore, an extrapolation of the data on the reaction cross sections to very low energies and to extremely high density situations is generally called for, which are substantially altered every now and then for a number of astrophysically important reactions. The ...
Macrokinetics of benzene sulfonation in liquid-liquid and gas-liquid systems has been studied in continuous mixed reactors. It has been shown that the rate of sulfonation of benzene at 25/sup 0/C in two liquid phases using concentrated sulfuric acid is kinetically controlled. Whereas the rate of the latter reaction by gaseous sulfur trioxide at the same temperature is largely affected by the diffusional phenomena. At this temperature, the rate of reaction in gas-liquid system was described by a model assuming a fast reaction in the liquid phase. However, by increasing the temperature, the fast reaction region gradually changed to instantaneous reaction regime. A model, describing such a regime has also been developed and verified experimentally.
A detailed chemical kinetic reaction mechanism is developed for primary reference fuel mixtures of n-hexadecane and 2,2,4,4,6,8,8-heptamethyl nonane for diesel cetane ratings. The mechanisms are constructed using existing rules for reaction pathways and rate expressions developed previously for the primary reference fuels for gasoline octane ratings, n-heptane and iso-octane. These reaction mechanisms are validated by comparisons between computed and experimental results for shock tube ignition and for oxidation under jet-stirred reactor conditions. The combined kinetic reaction mechanism contains the submechanisms for the primary reference fuels for diesel cetane ratings and submechanisms for the primary reference fuels for gasoline octane ratings, all in one integrated large kinetic reac...
A detailed chemical kinetic reaction mechanism is developed to describe incineration of the chemical warfare nerve agent sarin (GB), based on commonly used principles of bond additivity and hierarchical reaction mechanisms. The mechanism is based on previous kinetic models of organophosphorus compounds such as TMP, DMMP and DIMP that are often used as surrogates to predict incineration of GB. Kinetic models of the three surrogates and GB are then used to predict their consumption in a perfectly stirred reactor fueled by natural gas to simulate incineration of these chemicals. Computed results indicate that DIMP is the only one of these surrogates that adequately describes combustion of GB under comparable conditions. The kinetic pathways responsible for these differences in reactivity are identified and discussed. The most important reaction in GB and DIMP that makes them more reactive than TMP or DMMP is found to be a ...
This paper examines cupric chloride solid conversion during hydrolysis in a thermochemical copper-chlorine (Cu-Cl) cycle for hydrogen production. The hydrolysis reaction is a challenging step, in terms of the excess steam requirement and the decomposition of cupric chloride (CuCl_2) into cuprous chloride (CuCl) and chlorine (Cl_2). The hydrolysis and decomposition reactions are analyzed with respect to the chemical equilibrium constant. The effects of operating parameters are examined, including the temperature, pressure, excess steam and equilibrium conversion. A maximization of yield and selectivity are very important. Rate constants for the simultaneous reaction steps are determined using a uniform reaction model. A shrinking core model is used to determine the rate coefficients and predict the solid conversion time, with diffusional and reaction control. These new results are ...
The kinetics of the reactions between mixed powders of BaCO_3 and CuO, as well as BaCO_3 and Y_2O_3, have been studied using DXRD techniques as a function of particle size, temperature, and CO_2 pressure. Except for initial nucleation phenomena, the reaction rates are governed by shrinking core behavior for BaCO_3 particle sizes between 6 and 33 #mu#m. During the initial stages of the reactions, the surface reaction kinetics are governing, whereas the diffusion of CuO, Y_2O_3, and CO_2 are limiting factors at later stages in the reactions. Quantitative conversion data were used to determine the values of the activation energies and the pertinent diffusivities in these systems.
The reactions between (100) GaAs and the near-noble metals Ni, Pd, and Pt have been investigated by application of high-resolution transmission electron microscopy (TEM), energy-dispersive analysis of x rays in the scanning TEM and Rutherford backscattering spectrometry. Emphasis is placed on the evolution of the phase distributions, film compositions, and interface morphologies during annealing at temperatures up to 480 /sup 0/C. The first phase in the Ni/GaAs reaction is shown to have the nominal composition Ni/sub 3/GaAs. Ternary phases of the type Pd/sub x/GaAs are also found to be the dominant products of the Pd/GaAs reaction. Conversely, only binary phases result from the Pt/GaAs reaction. These observations are used to construct isothermal sections of the M--Ga--As thin-film phase diagrams. The behavior of a thin (1--2 nm) native oxide--hydrocarbon layer during the Ni/GaAs, Pd/GaAs, and Pt/GaAs ...
Theoretical interpretation of fast-charged-particle spectra, observed in the #alpha#-particle-induced reactions on the s-d shell nuclei (A = 24-28), in terms of the Intranuclear Cascade Model and the GDH exciton model (ALICE) is presented. The de-excitation of the excited residual nuclei is accounted for by the evaporation process. The theoretically predicted fast-proton and #alpha#' spectral shapes compare reasonably well with the corresponding measured spectra. However, the magnitude depends critically (as expected) on the reaction cross section employed by the model. As a first step to improve the model predictability of the reaction products, a closer look at the calculation of the #alpha#-particle reaction cross sections was undertaken. A microscopic approach using the optical theorem of Glauber's theory was employed to estimate the #alpha#-induced reaction cross sections for ...
Purpose: The results of therapy in 288 men with pathologic Stage C prostate cancer who underwent radical retropubic prostatectomy (RRP) were analyzed to determine the effects of adjuvant therapy. Methods and Materials: Twenty-seven of the 288 patients received preoperative neoadjuvant hormonal therapy (leuprolide acetate). Postoperatively, 60 patients received adjuvant radiotherapy (RT) to the prostate bed. Follow-up ranged from 3 to 83 months (median = 32 months). Freedom from failure (FFF) was defined as maintaining a serum PSA level of #<=# 0.3 ng/ml. Results: The FFF was 61% at 3 years and 45% at 5 years for the entire group. The FFF following RRP plus RT was 75% at 3 years and 57% at 5 years as compared to 56% at 3 years and 40% at 5 years for RRP without RT (p = 0.049). The FFF following RRP plus neoadjuvant hormonal therapy was 58% at 3 years and 40% at 5 years as compared to 60% at 3 years and 45% at 5 years following RRP without hormonal therapy (p = ...
The authors report the observation of B{sub s}{sup 0}-{bar B}{sub s}{sup 0} oscillations from a time-dependent measurement of the B{sub s}{sup 0}-{bar B}{sub s}{sup 0} oscillation frequency {Delta}m{sub s}. Using a data sample of 1 fb{sup -1} of p{bar p} collisions at {radical}s = 1.96 TeV collected with the CDF II detector at the Fermilab Tevatron, they find signals of 5600 fully reconstructed hadronic B{sub s} decays, 3100 partially reconstructed hadronic B{sub s} decays, and 61,500 partially reconstructed semileptonic B{sub s} decays. They measure the probability as a function of proper decay time that the B{sub s} decays with the same, or opposite, flavor as the flavor at production, and they find a signal for B{sub s}{sup 0}-{bar B}{sub s}{sup 0} oscillations. The probability that random fluctuations could produce a comparable signal is 8 x 10{sup -8}, which exceeds 5{sigma} significance. They measure {Delta}m{sub s} = 17.77 {+-} 0.10(stat) {+-} 0.07(syst) ...
Background and purpose: A diagnosis of malignancy and its treatment is a very stressful time for patients and their families. This study was conducted to determine the impact of more intensive written information on patients' anxiety levels. The secondary aim was to determine the impact of this information on patients' satisfaction levels. Materials and methods: This prospective randomized trial consisted of patients with a pathological diagnosis of cancer having radical radiotherapy (RT). Patients were randomized to receive the more intensive information (including written information and a telephone call from the research nurse) or not to receive the more intensive information at the time of their initial consultation with the radiation oncologist. Study questionnaires measuring anxiety (STAI form) were completed prior to their first consultation (baseline) at the time of simulation (pre-RT) and at the completion of radiotherapy. A second questionnaire assessing ...
Extensive research into the treatment and control of Volatile Organic Compounds (VOCs) from semiconductor industry manufacturing processes has identified the need for alternatives to existing combustion devices. Specifically, semiconductor manufacturing design is moving toward exploiting effective, small-scale, abatement control technologies for specific point-of-use (POU) waste streams associated with a particular component or manufacturing tool. The Silent Discharge Plasma (SDP) developed at Los Alamos National Laboratory is a nonthermal plasma technology created by a dielectric-ballasted electrical discharge. Influent gas-phase pollutants are destroyed in the reactor by the free radicals or electrons generated by the plasma. This paper examines the potential for SDP to be used in niche circumstances for POU control of VOC exhaust streams specific to the semiconductor industry. A sensitivity analysis is presented, showing how SDP cost of ownership is affected by ...
A study was conducted to determine the feasibility and the opportunity of photochemical pretreatment on the biodegradation and detoxification of Methyl Tert Butyl Ether (MTBE), Ethyl Tert Butyl Ether (ETBE) and Tert Amyl Methyl Ether (TAME), the most common oxygenates used as octane enhancers in unleaded gasoline. The production, storage, uses and disposal of oxygenates result in an unknown amount of groundwater pollution. Because of their high solubility, MTBE, ETBE and TAME are detected in large portions in saturated zones of aquifers. The biodegradation of these oxygenates is difficult and slow, and information regarding their biodegradability is scarce. Photo-decomposition of oxidants under appropriate UV radiation has been shown to be very effective because the hydroxyl radicals produced possess high oxidation potential. In this study, the H{sub 2}O{sub 2}/UV process was used to generate hydroxyl radicals. Maximal oxygenates transformation ...
A study was conducted to determine the feasibility and the opportunity of photochemical pretreatment on the biodegradation and detoxification of Methyl Tert Butyl Ether (MTBE), Ethyl Tert Butyl Ether (ETBE) and Tert Amyl Methyl Ether (TAME), the most common oxygenates used as octane enhancers in unleaded gasoline. The production, storage, uses and disposal of oxygenates result in an unknown amount of groundwater pollution. Because of their high solubility, MTBE, ETBE and TAME are detected in large portions in saturated zones of aquifers. The biodegradation of these oxygenates is difficult and slow, and information regarding their biodegradability is scarce. Photo-decomposition of oxidants under appropriate UV radiation has been shown to be very effective because the hydroxyl radicals produced possess high oxidation potential. In this study, the H_2O_2/UV process was used to generate hydroxyl radicals. Maximal oxygenates transformation was ...
The absolute cross sections of "2"3Na(p,n)"2"3Mg, "2"7Al(p,n)"2"7Si and "3"0Si(#alpha#,n)"3"3S reactions were measured in the incident energy range of 5.05 to 5.80, 5.80 to 6.25 and 3.975 to 6.235 MeV respectively using a spherically shaped 4#pi# neutron detector. In the energy range 5.80 to 7.80 and 6.235 to 11.30 MeV the absolute cross sections of "2"3Na(p,n)"2"3Mg and "3"0Si-(#alpha#,n)"3"3S reactions were determined by optical model calculations. The cross sections of the inverse reactions "2"3Mg(n,p)"2"3Na and "3"3S(n,#alpha#)"3"0Si were also calculated by the same method for the neutron energy range of 10 keV to 7.50 MeV for each reaction. The cross section of the latter reaction in the neutron energy range of 10 keV to 840 keV was also determined from its inverse reaction "3"0Si(#alpha#,n)"3"3S by the application of the detailed balance theorem. The ...
The effect of adriamycin in combination with radiation on the skin reactions of mouse feet has been examined under a variety of experimental conditions including: (a) hyperthermic treatment of the foot immediately following adriamycin administration, with the former given either just before or just after x irradiation, and (b) fractionated treatments of drug and radiation in a variety of sequences over an 18-day period. In the case of the most severe hyperthermic treatment, no increased radiation reactions were observed in the presence of adriamycin. However, in the case of the less severe hyperthermic treatment a small but significant increase in skin reactions was observed. In the study of fractionated drug and radiation treatments, an enhancement of reaction in those animals receiving combined modality treatment over those receiving radiation alone was seen in those groups where the initiation of ...
Enzymatic reactions in non-aqueous media have been shown to be effective in carrying out chemical transformation where the reactants are insoluble in water or water is a byproduct limiting conversion. Ionic liquids, liquid organic salts with infinitesimal vapor pressure, are potentially useful alternatives to organic solvents. It is known that the thermodynamic water activity is an important variable affecting the activity of enzymes in non-aqueous solvents. This study investigated the influence of water activity on the esterification of geraniol with acetic acid in ionic liquid [bmim]PF6 catalyzed by immobilized Candida antarctica lipase B. The conversion of geraniol in [bmim]PF6 was significant although the reaction rate was slower than in organic solvents. The profile of initial reaction rate-water activity was determined experimentally, and differed from the data reported for other non-aqueous solvents. A maximum in the ...
Despite the rapid development of literature pertaining to fundamental (1-4) studies of oxidation catalysis, a general theory of heterogeneous selective oxidation catalysis explaining the selectivity behavior of different metal oxide systems has not yet been developed. Redox mechanisms have been widely invoked in the kinetic and mechanistic descriptions of selective oxidation reactions, suggesting a dynamic behavior of hydrocarbon and oxygen interactions with the catalyst surface. Nevertheless, most of the recent theoretical approaches of this subject matter (5-7) are essentially static in nature. Correlations are made with surface structure on the basis of crystallographic considerations with selectivity being related to the nature, number, bond-strength and nearness of oxygen atoms in the neighborhood of adsorption centers. The effect of the reaction medium on the configuration of the catalyst surface, and thus its influence on the ...
Experimentally investigated nuclear reactions for production of no-carrier-added "7"7Br and "7"7Kr were critically surveyed. The survey covered nine reactions for the formation of "7"7Br and six reactions for "7"7Kr. Both radionuclides are simultaneously produced in many of the studied nuclear processes. The experimental data were compared with the results of nuclear model calculations based on the computer code ALICE-IPPE and the third version of TALYS-based Evaluated Nuclear Data Library, TENDL-2010. Good agreement was found over extended energy regions for the p-, "3He- and #alpha#-particle induced reactions on several target materials. In case of d-induced reactions, however, considerable discrepancies were noted between the experimental and theoretical data. The concordant sets of experimental cross section data for each reaction were fitted by a polynomial ...
In early 2004, the U.S. Department of Energy (DOE) Richland and Fluor Hanford requested technical assistance from the DOE Headquarters EM-23 Technical Assistance Program to provide a team of technical experts to develop recommendations for mending the In Situ Redox Manipulation (ISRM) Barrier in the 100-D Area of the Hanford Site in Washington State. To accommodate this request, EM-23 provided support to convene a group of technical experts from industry, a national laboratory, and a DOE site to participate in a 2 1/2-day workshop with the objective of identifying and recommending options to enhance the performance of the 100-D Area reactive barrier and of a planned extension to the northeast. This report provides written documentation of the team's findings and recommendations. In 1995, a plume of dissolved hexavalent chromium [Cr(VI)], which resulted from operation of the D/DR Reactors at the Hanford site, was discovered along the Columbia River shoreline and in the 100-D ...
Measurements were completed on the solubility of cupric and cuprous oxides in liquid water and steam at controlled pH conditions from 25 to 400 C (77 to 752 F). The results of this study have been combined with those reported from this laboratory in two previous EPRI reports to provide a complete description of the solubility of these oxides and the speciation of copper dissolved in liquid water and steam as a function of oxidation state, temperature, pH, and in the case of steam, pressure. These constitute the first set of reliable data for cuprous oxide solubility over this range of conditions. For the more intensively studied CuO case, agreement was found between our results and those of previous studies of its solubility in steam, whereas only partial agreement was evident for its solubility in liquid water. For both oxides this disagreement often amounted to orders of magnitude. The solubility of cuprous oxide is somewhat lower than that of CuO at ambient conditions, except as ...
The research has involved the characterization of catalyst acidity, [sup 2]D NMR studies of Bronsted acid sites, and kinetic, calorimetric, and spectroscopic studies of methylamine synthesis and related reactions over acid catalysts. Approach of this work was to explore quantitative correlations between factors that control the generation, type, strength, and catalytic properties of acid sites on zeolite catalysts. Microcalorimetry, thermogravimetric analysis, IR spectroscopy, and NMR spectroscopy have provided information about the nature and strength of acid sites in zeolites. This was vital in understanding the catalytic cycles involved in methylamine synthesis and related reactions over zeolite catalysts.
Schemata for modelling combustion processes do not yet include reaction rates for oxygenated fuels like methylal (DMM) which is considered as an additive or replacement for diesel due to its low sooting propensity. Density functional theory (DFT) studies of the possible reaction pathways for different dissociation steps of methylal are presented. Cleavage of a hydrogen bond to the methoxy group or the central carbon atom were simulated at the BLYP/6-311++G{sup **} level of theory. The results are compared to the experiment when dissociating and/or ionising DMM with femtosecond pulses. (author) 1 fig., 1 tab., 1 ref.
Geochemical model is a kind of concept model which describes geochemical processes by means of chemical reaction equations and mathematical formula, and the software based on the concept model are called geochemical modeling code. Geochemical modeling codes can be divided into three categories: mass equilibrium, mass transfer and mass transport code. The major functions of geochemical codes include the calculation of forms of occurrence of elements, the prediction of direction of various geochemical reaction, the dissolution and precipitation of elements, the pH and Eh value, the rate and path of geochemical reaction in aqueous solution.
Green River oil shale was air oxidized at subretorting temperatures. Off gases consisting of nitrogen, oxygen, carbon monoxide, carbon dioxide, and water were monitored and quantitatively determined. A mathematical model of the oxidation reactions based on a shrinking core model has been developed. This model incorporates the chemical reaction of oxygen and the organic material in the oil shale as well as the diffusivity of the oxygen into the shale particle. Diffusivity appears to be rate limiting for the oxidation. Arrhenius type equations, which include a term for oil shale grade, have been derived for both the chemical reaction and the diffusivity.
Nuclear reaction cross-sections for stable strontium and cesium isotopes, which were calculated by different approaches, are compared to available experimental data. Neutron and proton induced reaction cross-sections for the long-lived radionuclides [sup 90]Sr and [sup 137]Cs have been calculated in the energy range from 1 MeV to 10 GeV. Recommendations concerning cross-section calculations for strontium and cesium isotopes at intermediate and high energies are given. (orig.)
Discrepancies between the energy level schemes of "1"0"9Cd determined by radioactive decay studies and "1"1"0Cd(d, t) reaction studies were investigated by a new study of the "1"1"0Cd(d, t) reaction. Sixteen triton groups were found, J/sup pi/ assignments were made, and spectroscopic factors and fullnesses of single particle states were determined and compared with those for isotonic nuclei. The results remove or clarify all previous discrepancies.
The constants, applied in the phenomenological approaches for describing the nuclear reactions with the high transmitted pulse, are obtained within the frames of the multiquark flucton microscopic model. The constants values prove to be universal for all the nuclei and independent on the collision energy and flucton properties (excluding its mass), i.e. the peculiar scaling is manifested in the reaction cross sections. The theoretically obtained values of these constants are in good agreement with the phenomenological values, derived from the (p, p'X) reaction cross sections on the nuclei for X=d, t, "3He
In the reaction sup(nat)Ag + /sup 40/Ar (285 MeV) there have been measured the energy spectra of the isotopes of elements from H to Cl at an emission angle of 40/sup 0/, the energy spectra and angular distributions of /sup 1/H, /sup 2/H, /sup 3/H, and /sup 4/He, and the angular distributions of Li, Be, B, and C. The contribution from multinucleon transfer reactions to the formation of light charged particles is discussed.
Predicted by stochastic models and observed experimentally in a number of isomerization reactions, viscosity-induced solvent effects manifest themselves in a significant departure of the reaction rates from the values expected on the basis of transition state theory. These effects are well understood within the framework of stochastic models; however, the predictive power of such models is limited by the fact that their parameters are not readily available. Experiment and molecular dynamics (MD) simulations can provide such information and can serve as the testing grounds for various stochastic models. In real solvents, a change in viscosity is inevitably associated with variation of at least one of the three factors - temperature, pressure, or solvent identity, resulting in different solv...
The aim of this textbook is to present a relatively simple treatise of the theoretical principles and working methods of photochemistry, key photochemical reactions and important practical applications to enable the reader (a basic knowledge of chemistry is assumed) to work independently is this field. In accordance with the broad scale of this subject, which cuts across numerous disciplines, the topics treated range from photochemical, photophysical and spectroscopical fundamentals, through associated work procedures and methods of evaluation and the various types of reactions to photochemical processes in nature and applied technology. The photochemical properties and reactions of organic and inorganic compounds (preferably coordination compounds) are discussed in each chapter.
A 60-year-old male was bitten by a venomous snake (Vipera ammodytes) and gradually developed signs of an allergic reaction including generalized itching, generalized rash, and chest discomfort. This was followed by severe retrosternal pain with electrocardiographic evidence of an inferior myocardial ischemia progressing to acute myocardial infarction. Cardiac enzymes and troponin, serum tryptase, and histamine were elevated. Coronary arteriography showed normal coronary arteries. This is a characteristic type I variant of Kounis syndrome, which is the concurrence of acute coronary syndromes with conditions associated with mast cell activation including allergic or hypersensitivity reactions as well as anaphylactic or anaphylactoid reactions. This is the first report to show that viper bite...
We have investigated the stability and catalytic activity of epitaxial overlayers of rhodium on Au(111) and Pd(111). Both surfaces show a strong affinity for hydrogen. We have calculated the energy of adsorption both for a strongly and a more weakly adsorbed species; the latter is the intermediate in the hydrogen evolution reaction. Both the energy of activation for hydrogen adsorption (Volmer reaction) and hydrogen recombination (Tafel reaction) are very low, suggesting that these overlayers are excellent catalysts. PMID:21847482
Two patients are described in whom sunburn and electron beam radiodermatitis, respectively, were critical determinants in localizing the initial presentation of drug eruptions. In the first instance, a severe sunburn of the back and thighs was followed 7 months later by the appearance of a toxic epidermal necrolysis drug reaction to trimethoprim-sulfamethoxazole in the exact sites of the previous bullous sunburn reaction. In the second patient, a radiodermatitis of the left upper arm due to electron beam therapy for metastatic breast cancer was followed 7 weeks later by a codeine drug reaction confined to the area of the radiodermatitis. In both instances, oral rechallenge with the offending drug reproduced the eruption.
The energy spectra of few-nucleon transfer reactions obtained by bombarding a /sup 197/Au nucleus with the 341 MeV /sup 20/Ne beam of the Berkeley cyclotron have been analysed successfully in terms of direct surface transfer reactions populating the continuum states. At the grazing angle we are dealing with one-step processes; at forward angle two-step processes have to be taken into account.
In the reactions induced by heavy ions, the study of breakup of heavy ions followed by the fusion of one of the fragments with the target has been of great interest. The present experiments has been performed with a view to compare the measured excitation functions for the same decay channels in "1"2C + "1"6"5Ho and "1"4N + "1"6"3Dy systems
Bremsstrahlung emitted in the {alpha}+p reaction at 50 MeV/nucleon was studied using a 200 MeV {alpha}-particle beam and a liquid hydrogen target. Double-differential photon cross sections were measured over a wide range of angles and energies. Coherent bremsstrahlung was found to be strong for all photon energies. The cross section is enhanced at the highest photon energies and is characteristic of direct capture to the unbound {sup 5}Li ground and first excited state. With direct capture as a limiting case of coherent bremsstrahlung a consistent reaction picture can be obtained.
Monte Carlo criticality calculations have been performed for over 50 years for reactor physics and criticality safety applications. With today's faster computers, these calculations are being carried out to greater precision (smaller uncertainties) in keff, and detailed distributions of power and reaction rates are being computed routinely. This paper provides a review of the fundamental theory of Monte Carlo criticality calculations, with guidance on practical methods for: (1) assuring convergence of both keff and the source distribution, (2) minimizing the bias in keff and reaction rate distributions, and (3) dealing with the under-prediction bias in uncertainties for keff and reaction rate distributions. (authors)
In a double blind test on 40 men and women high performance fencers the influence of a multivitamin-electrolyte-preparation on reaction time, hit-frequency and neuromuscular irritability was determined....Full Text Available
Iodine-125 labelled vinyl and aryl iodides are formed via the reaction of sodium iodide-125 with vinyl- and arylboronic acids. Good yields of isomerically pure products are obtained.
Introduction.Microfluidic technology allows fast reactions in a simple experimental setup, while using very low volumes and amounts of starting material. Consequently, microfluidic technology is an ideal tool for radiolabeling reactions involving short-lived positron emitters. Optimization of the complex array of different reaction conditions requires knowledge of the different reaction parameters linked to the microfluidic system as well as their influence on the radiochemical yields. 1-(5-Deoxy-5-fluoro-?-d-arabinofuranosyl)-2-nitroimidazole ([18F]FAZA) is a frequently used radiotracer for PET imaging of tumor hypoxia. The present study describes the radiosynthesis of [18F]FAZA by means of microfluidic technology and subsequent small animal PET imaging in EMT-6 tumor-bearing mice.Methods...
The nitrogen content of 10 medicinal plant species has been determined by fast-neutron activation analysis (FNAA). Correction factors for the effects of the /sup 16/O(p,..cap alpha..)/sup 13/N knock-on proton-induced reaction and the (n,2n) reactions, which produce interfering positron-emitting radionuclides, have also been determined. The total relative interference from the /sup 16/O(p,..cap alpha..)/sup 13/N and (n,2n) reactions of K, Cl, Fe and Br was found to be 5.1 to 32.1% for the plant samples.
Neopentane, because of its unique structural features, was found to be a useful probe for the assay of the acidity of various zeolites. The C-C bond was attacked by catalyst protons yielding CH/sub 4/ and the isobutyl carbenium ion in equal quantities. The latter either decomposed to produce isobutene or underwent secondary reactions. New avenues for reaction were opened with isobutane. The reaction of the Bronsted protons with the tertiary CH bonds produced H/sub 2/ and the same isobutyl carbenium ion. Hydride ion transfer of the same tertiary hydrogen to existing carbenium ions also occurred and the results showed that about half of the reaction was carried by this pathway. As with Neopentane, the C-C bond could also be attacked yielding the sec-propyl carbenium ion. These tools are being further developed.
We report here results of an application of single-nucleon stripping reactions at high energies (65 MeV/u) in inverse kinematics to obtain spectroscopic factors. From measurements of the partial cross-sections for ground and excited states in residual nuclei formed in one-proton stripping reactions, single particle orbits and occupancies of light nuclei have been studied in the s-d shell. Single proton stripping cross-sections of {sup 25}Al and {sup 26,27,28}P on a Be target have been measured using the S800 spectrograph and the NaI(Tl) array at the NSCL. These results indicate that this technique may provide a general tool for the intermediate energy range analogous to transfer (pick-up) reactions at low-energy.
We report here results of an application of single-nucleon stripping reactions at high energies (65 MeV/u) in inverse kinematics to obtain spectroscopic factors. From measurements of the partial cross-sections for ground and excited states in residual nuclei formed in one-proton stripping reactions, single particle orbits and occupancies of light nuclei have been studied in the s-d shell. Single proton stripping cross-sections of "2"5Al and "2"6","2"7","2"8P on a Be target have been measured using the S800 spectrograph and the NaI(Tl) array at the NSCL. These results indicate that this technique may provide a general tool for the intermediate energy range analogous to transfer (pick-up) reactions at low-energy.
We show that the recently measured asymmetry in helicity-angle spectra of the #LAMBDA#-hyperons, produced in the reaction pp#->#K"+#LAMBDA#p reaction, and the energy dependence of the total pp#->#K"+#LAMBDA#p cross-section can be explained consistently by the same #LAMBDA#p final-state interaction. Assuming that there is no final-state interaction in the #SIGMA#"0 p channel, as suggested by the available data for the reaction pp#->#K"+#SIGMA#"0p, we can also reproduce the energy dependence of the #LAMBDA#/#SIGMA#"0 production ratio and, in particular, the rather large ratio observed near the reaction thresholds. The nominal ratio of the #LAMBDA# and #SIGMA#"0 production amplitudes squared, i.e. when disregarding the final-state interaction, turns out to be about 3, which is in line with hyperon production data from proton and nuclear targets available at high energies. (orig.)
Several reactions producing odd-Z transactinide compound nuclei were studiedwith the 88-Inch Cyclotron and the Berkeley Gas-Filled Separator at the LawrenceBerkeley National Laboratory. The goal was to produce the same compound nucleus ator near the same excitation energy with similar values of angular momentum via differentnuclear reactions. In doing so, it can be determined if there is a preference in entrancechannel, because under these experimental conditions the survival portion of Swiatecki, Siwek-Wilcznska, and Wilczynski's"Fusion By Diffusion" model is nearly identical forthe two reactions. Additionally, because the same compound nucleus is produced, theexit channel is the same. Four compound nuclei were examined in this study: 258Db, 262Bh, 266Mt, and 272Rg. These nuclei were produced by using very similar heavy-ion induced-fusion reactions which differ only by one ...
Deforestation farther inland causes delayed reactions. When roots no longer hold soil in place, it ends up muddying streams, rivers, and coastal waters. ...
Nuclear reaction rates and opacity are important parameters in stellar evolution. The input physics in a stellar evolution code determines the main theoretical characteristics of the stellar structure, evolution and nucleosynthesis of a star. For different input physics, in this work we calculate stellar evolution models of very massive first stars during the hydrogen and helium burning phases. We have considered 100 and 200M_sun galactic and pregalactic stars with metallicity Z = 10"-"6 and 10"9, respectively. The results show important differences from old to new formulations for the opacity and nuclear reaction rates, in particular the evolutionary tracks are significantly affected, that indicates the importance of using up to date and reliable input physics. The triple alpha reaction activates sooner for pregalactic than for galactic stars.
The available nuclear structure information for all nuclei with mass number A=242 is presented. Various decay and reaction data are evaluated. Adopted data, levels, spin and parity assignments are given.
Detailed level and decay schemes are presented for the nuclei of the A = 101 mass chain. The level properties obtained from decay and reaction experiments are shown in the drawings. Experimental methods, references, and comments are given in the text.
Detailed level and decay schemes are presented for the nuclei of the A = 101 mass chain. The level properties obtained from decay and reaction experiments are shown in the drawings. Experimental methods, references, and comments are given in the text.
The energy level schemes of tin isotopes produced in the heavy ion reactions are presented. The using of #gamma# spectroscopy technique is also described. 4 refs, 12 figs.
Histamine and the histamine receptors are important regulators of a plethora of biological processes, including immediate hypersensitivity reactions and acid secretion in the stomach. In these...Full Text Available
Neutron yield from the "6","7Li + d reaction has been investigated. The results obtained are compared with the published data with some theoretical models.
Neuroleptic malignant syndrome is a life-threatening reaction of neuroleptic medication. The estimated incidence rate of neuroleptic malignant syndrome is between 1% and 1.5% of patients treated with...Full Text Available
Monitoring describes the prospective supervision, observation, and testing of an ongoing process. The result of monitoring provides reassurance that the goal has been or will be achieved, or suggests...Full Text Available
Multi-core MgB_2/Ti/Cu/SS composite wire has been made by the in situ approach. Mechanical properties, interdiffusion reactions and critical currents were studied after heat treatments at temperatures between 500 and 850 "0C. Cu diffusion into the Ti layer occurs for all samples, resulting in the formation of intermetallic compounds at the Cu/Ti interface. EDX analysis has revealed the temperature dependence of all interface reactions. In spite of element reactions the critical current densities 10"5 A cm"-"2 and 10"4 A cm"-"2 were measured in liquid helium at magnetic fields 5 T and 9.5 T, respectively. 10"4 A cm"-"2 at 20 K is measured in an external field of 4 T.
One measured fission and fusion cross sections of "4","6He+"2"0"9Bi and "7Li+"2"0"8Pb reactions within the range from the Coulomb barrier up to 200 MeV. The measured functions of fission and fusion for the mentioned reactions are shown to have close values within the excitation energy wide range. One analyzed the excitation functions of fusion and fission for "4He+"2"0"9Bi, "6He+"2"0"9Bi and "7Li+"2"0"8Pb reactions resulting in formation of "2"1"3","2"1"5At compound systems
Rapid nitridation was used to fabricate reaction-bonded and postsintered -Si6-ZAlZOZN8-Z (Z=1) ceramics with monoclinic ZrO2 added to the starting powder. Thermo-gravimetric analysis revealed that the addition of ZrO2 reduced the starting temperature of the main nitridation reaction. Using a reaction-bonding route with heating rates of 5, 10, and 20C/min, to fabricate -SiAlON ceramics without ZrO2 resulted in unreacted silicon that bled out of the specimens and the Z=1 composition samples did not maintain the original green compact morphology. On the other hand, no such bleeding of melted silicon was observed for samples with ZrO2 additions and the samples following nitridation maintained the original green morphology. The microstructure and mechanical properties of samples produced by rap...
Abstract The characteristics of desulfurization and denitrification with composite absorbent were researched through aqueous absorption experiments. The removal efficiencies of SO2 and NO were up to 100 and 95%, respectively. The composite absorbent included NaClO2 and component M. Existence of component M in the solution could reduce the absorbent cost compared with using sodium chlorite alone. Chlorine dioxide, as main reaction intermediate product, participated in oxidation reaction. The optimal experimental conditions involved NaClO2 concentration of1.13 mmol/L, solution pH of 5.5, molar ratio (M/NaClO2) of 4.1, reaction temperature of 323 K. The optimal solution pH and reaction temperature were both in the required ranges of limestone-gypsum wet flue gas desulfurization (FGD) process....
Purpose - This paper discusses the impact of aesthetic design of smartphones on users' emotional reactions and preferences towards the product. To this end, the paper presents a study that explores emotional reaction of males to varying aesthetic design of the BlackBerry and empirically evaluates their preferences for the BlackBerry in different colours and overlay patterns. The paper then presents the statistical results of the study in an innovative graphical representation. Design/methodology/approach - A quantitative and qualitative research design was used, including three types of data-collection instruments (direct observations, rating scales, and interviews) to investigate if males have a stronger positive emotional reaction for visually treated BlackBerry Pearl devices over the or...
CuO/bentonite and CuO-BHA nanocomposites were studied as oxygen carriers in chemical-looping combustion (CLC) of simulated synthesis gas. Global reaction rates of reduction and oxidation, as the function of reaction conversion, were calculated from 10-cycle oxidation/reduction tests utilizing thermogravimetric analysis at atmospheric pressure between 700 and 900{degree}C. It was found that the reduction reactions are always faster than oxidation reactions; reaction temperature and particle size do not significantly affect the reaction performance of CuO/bentonite. Multicycle CLC tests conducted in a high-pressure flow reactor showed stable reactivity for production of CO{sub 2} from fuel gas at 800 and 900{degree}C and full consumption of hydrogen during the reaction. Results of the tapered element oscillating microbalance showed a negative ...
The atmospheric processing by ozone of peptide-containing mixed particles was investigated as proxies for biogenic and sea spray primary organic aerosol. Reactions were performed in a flow reactor and particle composition was monitored by photoelectron resonance capture ionization aerosol mass spectrometry. Mixed particles containing dipeptides in a saturated organic matrix of stearic and palmitic acids showed no reaction under ozonolysis at exposure levels of 2.5???10?4?atm s O3. However reactions of mixed particles of a dipeptide (Leu-Leu) in an unsaturated matrix (oleic acid) under the same conditions resulted in a rapid loss of the peptide ion signal, as well as the carrier matrix, and appearance of a number of ion signals corresponding to secondary products. High molecular weight imid...
BackgroundOsseointegration is crucial for the long-term success of dental implants and depends on the tissue reaction at the tissue-implant interface. Mechanical properties and biocompatibility...Full Text Available
Comparisons of calculated neutron yield distributions from #alpha#-particle induced reactions on thick targets are made with measured data to analyze the initial reaction process in the framework of the exciton (hybrid) model code ALICE91 (M. Blann, Lawrence Livermore National Laboratory Report UCID 19614, 1982). We have considered two reaction mechanisms: dissolution of the #alpha# in the nuclear field, and preequilibrium processes initiated by #alpha#-nucleon collisions. Both these processes seem to contribute to the emitted neutron spectra in varying proportions depending on the incident #alpha# energy and possibly on the target nucleus. Contributions from other processes appear to be non-negligible.
Chemically reactive compounds in tissues can be monitored through their products of reaction with biomacromolecules. For the purpose of in vivo dose monitoring, hemoglobin (Hb) has been preferred to...Full Text Available
The reaction of ethanol on unreduced and H{sub 2}-reduced CeO{sub 2} and 1 wt% Pd/CeO{sub 2} has been investigated by steady state reactions, temperature programmed desorption (TPD), and in situ Fourier transform infrared (FT-IR) spectroscopy. Steady state reactions have shown a zero reaction order dependency for diatomic oxygen at and above 20%, while the addition of Pd to CeO{sub 2} decreases the apparent activation energy of the reaction from 75 kJ/mol on CeO{sub 2} alone to 40 kJ/mol (Pd/CeO{sub 2}). TPD experiments following ethanol adsorption on both CeO{sub 2} and Pd/CeO{sub 2} have shown desorption profiles corresponding to unreacted ethanol and various reaction and decomposition products (acetaldehyde, acetone, CO, CO{sub 2}, and methane). Ethanol conversion to reaction products was increased by the addition of Pd, from 15 to 30% on ...
Measurements are made of the isomeric ratio for the (n,2n) and (#betta#,n) reactions on the neutron-deficient nuclei _9_2Mo, _9_0Zr, _8_6Sr and _7_4Se. A method is developed for calculating the isomeric ratio for a low excitation energy of the residual nucleus. The good agreement found between experimental results and calculations for the (#betta#,n) reaction confirms the choices of residual nucleus characteristics, transmission coefficients of neutrons emitted etc. used in the calculations. The results of a study of the (n,2n) reaction were used to find the spin dependences of nuclear level density in the excitation energy region approx. 14 MeV. (author).
A simple semianalytical calculation is used to study how a star reacts when its central stock of hydrogen is exhausted and before the next fusion reaction based on helium begins.
SummaryA microreactor for electrochemical synthesis has been designed and fabricated. It has been shown that different reactions can be carried out successfully using simple protocols.
The core-shell luminol-doped SiO2 nanoparticles were synthesized and immobilized on the surface of chitosan film coating graphite electrode by the self-assembled technique. Then, a novel electrogenerated chemiluminescence (ECL) sensor for pyrogallol was developed based on its ECL enhancing effect for the core-shell luminol-doped silica nanoparticles. The ECL analytical performances and the sensing mechanism of this ECL sensor for pyrogallol were investigated in detail. The corresponding results showed that: compared with the conventional ECL reaction procedures by luminol ECL reaction system, the electrochemical (EC) reaction of pyrogallol and its subsequent chemiluminescence (CL) reaction occurred in the different spatial region whilst offering a high efficiency to couple the EC with the ...
The work is devoted to a microscopic analysis of the reactive capacity of chitin. An algorithm for modeling the deacetylation reaction in a monomeric unit of chitin is described. The reaction coordinate and the potential energy surface topography are determined taking into account the electron-vibrational interaction and low-symmetry perturbations within Jahn-Teller theory. Based on this algorithm, the topological modeling of the deacetylation process is performed for the first time and a mechanism of the biological activity of chitosan is proposed.
The study concerns 1984-1991. The wind park consists of 18 three-bladed 300 kW horizontal axis wind turbines of 35 meters height, and a rotor diameter of 30 meters, seven meteorological towers, and three cluster and control buildings. Aspects studied included disturbance of breeding, resting or feeding, and migrating birds, behavior of birds approaching the wind turbines during the day and night, and bird victims due to collision with the wind turbines and the meteorological towers. The flight behavior of birds approaching the wind park system during daylight is also dealt with. For at least a fifth of the observations it was noted whether the birds passing within 100 meters distance of a turbine showed a reaction or not. The proportion of the reactions was related to the wind park in operation or not in operation, and to the distance between the wind turbines, species, flight height, the passing distance, wind direction and wind force. ...
An investigation of the mechanism of the oxidation and ammoxidation of propylene was made. The products of the above reactions were acrylonitrile and acrolein for ammoxidation and oxidation, respectively. Also, the ammoxidation and oxidation of allyl alcohol, allyl amine, and their allylic deuterium substituted analogues was studied. It was concluded that oxidation and ammoxidation of propylene have the same rate determining step. Other conclusions about the reaction intermediates were also made.
The results of photoneutron spectra measurements for the reaction (#gamma#,n) on the Sr-88 nuclei near threshold are presented. The parameters of resonance levels, as well as radiative S_#gamma#"("1") and neutron S_n"("1") strength functions for transitions on the first excited level of Sr-87 were obtained. 2 refs.; 1 fig.; 1 tab.
The status of neutron activation cross sections for some threshold reactions important for reactor materials dosimetry is reviewed. An attempt is made to understand and explain discrepancies between integral and differential data, using recent available experimental results. The importance of standard and benchmark neutron fields for testing differential data for reactor dosimetry is emphasized and the Interlaboratory Reaction Rate (ILRR) program, as well as a similar program pursued by the IAEA, are briefly described.
Lithium (Li) plating-stripping reaction properties at the lithium phosphorus oxynitride glass electrolyte (LiPON)/copper thin film (Cu) interface is improved by the insertion of nano-thickness platinum (Pt) layer at the interface. The LiPON films are formed on mirror-polished lithium-ion conductive solid electrolyte sheets, and current collector thin films of Li, Cu-Pt multi layer, and Cu are formed on the LiPON films. The plating-stripping reactions at the LiPON/current collector films interface are carried out by galvanostatic and potential sweep measurements. Galvanostatic measurements reveal that Pt layer insertion reduces the overvoltage of the reaction and improves its coulomb efficiency. Also, cyclic voltammetry measurement suggests formation of Li-Pt alloys at higher voltages than 0 V (vs. Li/Li{sup +}) during the lithium plating process. Scanning electron microscopy observation clarifies that platinum insertion ...
Calorimetry testing of Tri-n-butyl phosphate (TBP) saturated with strong nitric acid was performed to determine the relationship between vent size and pressure buildup in the event of a runaway reaction. These experiments show that runaway can occur in an open system, but that even when runaway is induced in the TBP/HN0{sub 3} system, dangerous pressure buildup will be prevented with practical vent size.
This report discusses the following topics: Fusion-fission in light nuclear systems; High-resolution Q-value measurement for the {sup 24}Mg+{sup 24}Mg reaction; Heavy-ion reactions and limits to fusion; and Hybrid MWPC-Bragg curve detector development.
Reaction kinetics for the displacement of 5-aminoquinoline (5-Aq) and diethyl sulfide (SEt{sub 2}) from cis-[PtPh{sub 2}(CO)(L)] (L = 5-Aq or SEt{sub 2}) by aliphatic amines was measured for a wide array of amines. Reaction products were characterized by IR and NMR spectroscopies and crystalk structures of selected products were reported. Steric effects on the substitutions were discussed.
An e.p.r. spectrum of the reduced form of the electron-transport component (X), thought to be the primary electron acceptor of Photosystem I, was obtained. By using line-shape simulations of this component...Full Text Available
To simulate the effects of the breakup channel on rearrangement amplitudes, the conventional coupled-reaction-channel (CRC) expansion is augmented by pseudoreaction channels. The construction of the projector for the extended CRC space is discussed, and transition-operator equations on this space are given. By solving the full and post-approximation forms of the CRC equations for a model three-particle problem, the crucial role played by the nonorthogonality terms is demonstrated.
To simulate the effects of the breakup channel on rearrangement amplitudes, the conventional coupled-reaction-channel (CRC) expansion is augmented by pseudoreaction channels. The construction of the projector for the extended CRC space is discussed, and transition-operator equations on this space are given. By solving the full and post-approximation forms of the CRC equations for a model three-particle problem, the crucial role played by the nonorthogonality terms is demonstrated.
The mechanism of chemical poisoning of model heterogeneously catalyzed reactions on transition metal surfaces is studied. Clean Mo(001) surfaces were characterized; results suggest a first-layer contraction of 10% of the bulk interlayer spacing. Characterization of clean Co(0001) surfaces is underway. Decomposition of formic acid on Mo(001) surfaces is being studied. (DLC)
An intermetallic compound Sm[sub 2]Fe[sub 17]N[sub x] was synthesized by plasma nitriding of Sm[sub 2]Fe[sub 17] in a stream of N[sub 2]-H[sub 2] mixed gas. The reaction proceeded at a lower temperature (around 423 K) than that of the conventional thermal technique, but not at room temperature. This is discussed on the basis of the difference between the reaction mechanisms of plasma and thermal nitridings. (orig.)
The change of the transport coefficient due to the fusion energy source is studied. The scale invariance property of the reduced set of equations is investigated in the presence of the self-heating term due to the fusion reaction. The pressure gradient as well as the fusion power are the free energy sources that dictate the turbulent transport. It is shown that the burning transport coefficient can have a form with much wider variety, and that the transport property could be different owing to the self-heating by the fusion reactions. (author)
Transient enhanced diffusion in boron-implanted silicon is interpreted as being due to the fact that during rapid thermal annealing a relaxation process takes place, associated with quasi-chemical reactions including defects. A simple analytical model makes it possible to describe the annealing mechanism on a microscopic scale in terms of reaction-diffusion processes. The measured dependences of the boron diffusion coefficient of the enhanced diffusion on time, temperature and implantation energy are satisfactorily explained. (author).
Transient enhanced diffusion in boron-implanted silicon is interpreted as being due to the fact that during rapid thermal annealing a relaxation process takes place, associated with quasi-chemical reactions including defects. A simple analytical model makes it possible to describe the annealing mechanism on a microscopic scale in terms of reaction-diffusion processes. The measured dependences of the boron diffusion coefficient of the enhanced diffusion on time, temperature and implantation energy are satisfactorily explained. (author).
An approach to high energy nuclear reactions (relativistic nuclear physics) is developed on the basis of the quark-parton-flucton concept. The main assumptions underlying the known parton chain model are briefly reformulated, modified and generalized to the flucton case. This new model is used to investigate electron-nuclei and muon-nuclei inclusive reactions within the framework of quantum electrodynamics. The theoretical results are fitted well with existing data. (Auth.).
Projectilelike fragments following the 80 MeV /sup 16/O+/sup 27/Al reaction have been detected using a Bragg-curve spectroscopy ionization chamber (BCS-IC). The atomic number is deduced from the Bragg-peak amplitude. Nitrogen isotopes are clearly resolved using either range or energy loss data. This is the first application of the BCS method for complete ion identification in a heavy-ion-induced reaction.
Projectilelike fragments following the 80 MeV "1"6O+"2"7Al reaction have been detected using a Bragg-curve spectroscopy ionization chamber (BCS-IC). The atomic number is deduced from the Bragg-peak amplitude. Nitrogen isotopes are clearly resolved using either range or energy loss data. This is the first application of the BCS method for complete ion identification in a heavy-ion-induced reaction.
A method and apparatus is provided for detecting explosives by thermal imaging. The explosive material is subjected to a high energy wave which can be either a sound wave or an electromagnetic wave which will initiate a chemical reaction in the explosive material which chemical reaction will produce heat. The heat is then sensed by a thermal imaging device which will provide a signal to a computing device which will alert a user of the apparatus to the possibility of an explosive device being present.
The reaction of uranium oxides and chlorine to prepare anhydrous uranium tetrachloride (UCl{sub 4}) are important to more economical preparation of uranium metal. The most practical reactions require carbon or carbon monoxide (CO) to give CO or carbon dioxide (CO{sub 2}) as waste gases. The chemistry of U-O-Cl compounds is very complex with valances of 3, 4, 5, and 6 and with stable oxychlorides. Literature was reviewed to collect thermochemical data, phase equilibrium information, and results of experimental studies. Calculations using thermodynamic data can identify the probable reactions, but the results are uncertain. All the U-O-Cl compounds have large free energies of formation and the calculations give uncertain small differences of large numbers. The phase diagram for UCl{sub 4}-UO{sub 2} shows a reaction to form uranium oxychloride (UOCl{sub 2}) that has a good solubility in molten UCl{sub 4}. ...
Levels in "7"2Se were observed via in-beam gamma spectroscopy following the "5"8Ni("1"6O,2p) reaction. Spectra and partial energy level schemes are shown. (3 figures) (U.S.).
X-ray diffraction was used to monitor the {ital in} {ital situ} reaction of Pd deposited on Si(111) at room temperature. An ordered silicide forms spontaneously beneath a poorly ordered overlayer. It is commensurate and strained at low coverage, but relaxes to an unstrained state above a critical thickness of 18 A. During both phases of growth sustained intensity oscillations are seen that correspond to a layerwise consumption of the substrate at the buried interface.
The kinetics of the reaction of zirconium phosphates with carbon tetrachloride in sodium and potassium chloride melt as well as the effect of temperature, gas flow, solubility and weight of the solid phase of the phosphate, and stirring of the melt on the chlorination rate has been studied. The kinetic parameters of the reaction (rate constants, activation energy, etc.) have been calculated.
Thermodynamic analysis of dissolution processes of tungsten minerals in citric acid solutions in the absence and in the presence of hydrochloric acid has been carried out by means of calculation of Gibbs energy of the chemical reactions. Kinetic characteristics, such as specific dissolution rates and activation energies, are determined. It is established that the dissolution reactions studied take place in kinetic region. A possibility of scheelite selective dissolution in the presence of other tungsten minerals is shown.
In studying the absorption of carbon dioxide by absorbents impregnated with alkanol amines, researchers used a laboratory-scale packed column to determine the overall gas-phase mass-transfer coefficients and enhancement factors. A model derived for the mechanism of the chemical reaction taking place in the interfacial layer accounts for the effect of the reaction upon the absorption rate better than other models.
Details of a series of reactions for the production of ethylene glycol using a catalyst of Nafion solid perfluorosulfonic acid resin was detailed. The reactions included the carbonylation of formaldehyde and esterification and then hydrogenation of the product of the carbonylation, glycolic acid. Other preparations included in the work included methyl glycolate, acetylglycolic acid, methyl acetylglycolate, and methyl methoxyacetate.
Standard SCR catalysts possess high activity for the hydrolysis of HNCO and thus explain the suitability of urea as a selective reducing agent for NO{sub x}. At high space velocities HNCO-slip can get perceptible over the entire temperature range. This can be attributed to the fact that the temperature dependence is strong for the SCR reaction, but weak for the hydrolysis reaction. (author) 3 figs., 5 refs.
The H-D exchange reaction has been measured with the D2-H2O system, for Rhodobacter capsulatus JP91, which lacks the hupSL-encoded hydrogenase, and R. capsulatus BSE16, which lacks the HupUV proteins....Full Text Available
We study the dynamics of scroll vortices in excitable reaction-diffusion systems analytically and numerically. We demonstrate that intrinsic three-dimensional instability of a straight scroll leads to the formation of helicoidal structures. This behavior originates from the competition between the scroll curvature and unstable core dynamics. We show that the obtained instability persists even beyond the meander core instability of the two-dimensional spiral wave. copyright 1998 The American Physical Society.
A facility for studying photon-neutron reactions under a braking #gamma#-beam with an energy of up to 26 MeV from a betratron includes Saratov-2, SM-4A, and IBM AT-386 microcomputers. Neutron detectors, pulsed braking radiation dosimeters, and the devices to control the betatron energy are described.
An experiment to synthesize element 110 by the {sup 59}Co+{sup 209}Bi reaction has bee performed at the SuperHILAC at the Lawrence Berkeley Laboratory. One event with many of the expected characteristics of a successful of {sup 267}110 was observed. This event corresponds to a production cross section of about one picobarn.
The endogenous reverse transcriptase reaction of equine infectious anemia virus (EIAV) has been studied, and conditions allowing synthesis of full-length minus-strand DNA have been determined. In contrast...Full Text Available
The enzyme indol-3-ylacetylglucose synthase (UDP-glucose:indol-3-ylacetate beta-D-glucosyltransferase) catalyses the reaction: [formula: see text] This is the first step in the series of reactions leading...Full Text Available
This paper reports the effectiveness of solvents on the liquefaction of 11 different Turkish lignites investigated by using tetralin, creosote, and anthracene oils. The highest total conversions were obtained with tetralin. The catalytic effects of CoMo and red mud were compared by using creosote oil as the solvent. It was found that red mud catalyzed mainly the asphaltene formation reaction for the given experimental conditions. The additional of CoMo significantly catalyzed the liquefaction reaction, thus increasing the lignite conversion and oil formation.
A ligase chain reaction assay based on a single-base-pair difference in the V9 region of the 16S rRNA gene (16S rDNA) was developed to distinguish between Listeria monocytogenes and other Listeria species....Full Text Available
The cross section for the reaction "8"8Sr(n,p)"8"8Rb was found to be (0.0155 +- 0.0017) mb. This value corresponds well with those calculated by Roy, Hawton, Calamand, and Nasyrov. (author).
A two-step polymerase chain reaction (PCR) procedure with two nested pairs of primers specific for the yadA gene of Yersinia enterocolitica was developed. The PCR assay identified all common pathogenic...Full Text Available
A large IMF- and event characterizing multidetector system (CHICSI) is under development for storage ring experiments. In ''test'' experiments with telescopes of CHICSI type the IMF production has been measured for "1"4N induced reactions at 14A and 32A MeV. Detailed information about the emission sources, particularly from the IMF yield in reactions with isotope separated targets and from isobaric yield ratios in the sub-Coulomb region is discussed. (orig.).
The experimental has been performed with a view to studying complete and incomplete fusion in "1"4N + "1"6"3D_y system below 7 MeV/nucleon. The excitation functions for several reactions have been measured using the activation technique and compared with the theoretical predictions based on statistical models. The codes ALICE-91 and CASCADE used earlier for the analysis of excitation functions in case of "1"2C + "1"6"5H_0 system have been used here also with the same set of input parameters. It has been observed that the theoretical calculations do not match with the experimental excitation functions well but the overall shape of the excitation function is reproduced satisfactorily. The composite nucleus ("1"7"7T_a) formed in this ("1"4N + "1"6"3D_y) case is the same as the one formed in "1"2C + "1"6"5H_0 system studied earlier. Measured excitation functions for the same decay channels in the two cases (i.e. "1"2C + "1"6"5H_0 and "1"4N + "1"6"3D_y) have been ...
We conducted (n, #gamma#) and (d, p) reactions leading to "8"7", "8"8", "8"9"Sr in addition to "8"8Sr (d, t) "8"7Sr and 24 keV neutron capture in "8"8Sr. (orig./HSI).
Chemical looping combustion (CLC) of simulated coal-derived synthesis gas was conducted with NiO oxygen carriers supported on SiO2, ZrO2, TiO2, and sepiolite. The effect of H2S on the performance of these samples for the CLC process was also evaluated. Five-cycle thermogravimetric analysis (TGA) tests at 800 C indicated that all oxygen carriers had a stable performance at 800 C, except NiO/SiO2. Full reduction/oxidation reactions of the oxygen carrier were obtained during the five-cycle test. It was found that support had a significant effect on reaction performance of NiO both in reduction and oxidation rates. The reduction reaction was significantly faster than the oxidation reaction for all oxygen carriers, while the oxidation reaction is fairly slow due to oxygen diffusion on NiO layers. The reaction profile was greatly affected by the presence of H2S, but ...
Results of an experimental study of the interaction of 140 MeV alpha particles with /sup 90/Zr nuclei resulting in fragmentation of the alpha particle are reported. The experimental observations of the study are analyzed and are found to show that alpha particle breakup reactions leading to at least 4-body final states, composed of two charged alpha particle fragments, contribute significantly to the singles yield of charged fragments observed at a fixed forward angle. The conclusions are based on coincidence measurements where one charged fragment is detected at a small forward angle which remains fixed, while the second charged fragment is detected at a series of coplanar secondary angles. The largest coincidence charged particle yield for the multiparticle final state events results from /sup 90/Zr(..cap alpha..,pp)X reactions, where both of the measured protons have energy distributions similar to the proton singles energy distributions. ...
Results of an experimental study of the interaction of 140 MeV alpha particles with _9_0Zr nuclei resulting in fragmentation of the alpha particle are reported. The experimental observations of the study are analyzed and are found to show that alpha particle breakup reactions leading to at least 4-body final states, composed of two charged alpha particle fragments, contribute significantly to the singles yield of charged fragments observed at a fixed forward angle. The conclusions are based on coincidence measurements where one charged fragment is detected at a small forward angle which remains fixed, while the second charged fragment is detected at a series of coplanar secondary angles. The largest coincidence charged particle yield for the multiparticle final state events results from _9_0Zr(#alpha#,pp)X reactions, where both of the measured protons have energy distributions similar to the proton singles energy distributions. The second ...
Cathodic reduction of non-terminal vinylaxides on Hg cathodes in the presence of electrophiles gives reasonable yields of N-acylated enamines in an electrochemically totally irreversible reaction. In the presence of added H-donors rather high selectivity for formation of saturated amides is achieveable. The influence of reaction conditions on product distribution is discussed.
Most chemical reactions in industry and biology are catalytic and play a role at some stage of the processing of about 80% of the goods manufactured in the U.S., yet catalysis is a neglected subject in chemical education. This book integrates the fragmentary treatment accorded the topic until now. It covers, in a unified way, catalysis in solutions, by enzymes, in synthetic polymers within the molecular scale cages of zeolites and other molecular sieves, and on surfaces of inorganic solids. The central ideas are chemical; and principles are illustrated by emphasizing industrial reactions and catalysts.
We consider a nonlinear reaction-diffusion equation settled on the whole euclidean space. We prove the well-posedness of the corresponding Cauchy problem in a general functional setting, namely, when the initial datum is uniformly locally bounded in L^2. Then we adapt the short trajectory method to establish the existence of the global attractor and, if the space dimension is at most 3, we also find an upper bound of its Kolmogorov's entropy.
The catalytic liquefaction of a Chinese bituminous coal was simulated by artificial neural network. Three liquefaction variables, catalyst loading, reaction temperature and reaction time were used as inputs and tetrohydrofuran (THF) conversion and toluene (T) conversion were used as outputs. The artificial neural network, trained by the experimental data, could represent the liquefaction process, with a mean squared deviation of less than 0.025. 7 refs.,1 fig., 3 tabs.
The doping of deuterated polyparaphenylene [C_6D_4]sub(n) with AsF_5 has been investigated by real time neutron diffractometry at 100, 400 and 820 mbar AsF_5 pressure. The reaction appears to be diffusion controlled. Evidence for one doped phase with partial crystalline order was obtained. Structural considerations suggest two polymer chains plus one dopant ''string'' as the repetitive unit. (Auth.).
This paper summarizes substance flow analyses for four organic substances in the City of Stockholm, Sweden: diethylhexyl phthalate (DEHP), alkylphenolethoxylates (APEO), polybrominated diphenylethers (PBDE) and chlorinated paraffins (CP). The results indicate that the stocks of APEO, PBDE and CP all are approximately 200-250 tonnes, whereas the DEHP stock is two orders of magnitude larger. Emissions can be linked to imported consumer goods such as electronics (PBDE) and textiles (APEO), and to construction materials (DEHP, CP). For several of the substances considerable amounts remain in the technosphere for a long time, even after use of the substance in new products has been eliminated. For example, the use of DEHP as plasticizer for PVC plastics in cables and floorings has more or less been phased-out, but still these applications make up a stock of some 20,000 tonnes (85% of the total DEHP stock in Stockholm) and emit 28 tonnes of DEHP annually (93% of overall emissions). Likewise, ...