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Showing 1 to 20 of 389 for “"rate constants"”.
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Measuring rate constants and product branching for reactions relevant to combustion and atmospheric chemistry
… chemical calculations combined with modem rate theories have become common. However, there are few experimental measurements against which to validate predicted product branching, even for an important reaction system such as hydroxyl radical addition to acetylene that is critical to …
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Prediction of the Degradation of Emerging Contaminants During Oxidative Treatment via Analysis of Reaction Rate Constants
… as AOP efficacy indicator compounds. Reaction rate constants were determined from batch reactor data and compared to the degradation trends observed for the different compounds after exposure to treatment. During exposure to ozone alone, caffeine degraded quickly (KO3 = 334 ± 67 M-1 s-1), …
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High Pressure Effects on the Dynamics and Kinetics of Two Model Biochemical Systems
Pressure effects on rate constants for hydrogen exchange between N-methylacetamide (NMA) and water were measured at pressures up to 5 kbar at three different pH values and temperatures using proton/nitrogen-14 decoupled NMR inversion transfer, and the apparent activation volumes of exchange …
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Rates of acidic hydrolysis of triptych boroxazolidines
Upon looking at the results of calculation of the rate constants given in Table 2, there are revealed some general trends as to the influence of the substituent groups on the values of the rate constants. If the rate constants of the reaction are considered at a fixed temperature, the rates of …
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Quantitative Kinetic Analysis of Olefin Polymerization by Single-Site Group IV Amine Bis-Phenolate Catalysts
… ones, their major advantage is that the kinetic rate constants may be manipulated through precise changes to the catalyst structure and reaction conditions. Such a process yields tailored polymers not generally available through heterogeneous catalysis. Two breakthroughs are needed in this field …
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Photolysis Kinetics of Aromatic Pollutants in Liquid and Solid Environmental Condensed Phases
… done under simplified conditions that do not accurately reflect the complexity found in the environment. I have measured photolysis rate constants of the aromatic pollutants toluene, ethylbenzene, xylenes (TEX) and anthracene under environmentally-relevant conditions in order to improve fate …
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Relative rates of reaction of pyrite and marcasite with ferric iron at low pH
… ferric iron concentrations of 10⁻³ molal. The rate of the reaction: FeS₂ + 14Fe³⁺ + 8H₂O = 15Fe²⁺ + 2SO₄²⁻ + 16H⁺ was determined by calculating the rate of reduction of aqueous ferric ion from measured oxidation-reduction potentials. The reaction follows the rate law: -d m<sub>Fe³⁺</sub> / dt = …
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Computational Tools for Molecular Networks in Biological Systems
… algorithms for estimating molecular reaction rate constants within those mathematical models by fitting the models to experimental data. An additional step is taken to fit non-timecourse experimental data (e.g., transformations must be performed on the ODE solutions before the experimental and …
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Degradation of polylactic acid in the presence of microsize and nanosize fillers
… in air at 180 C and 200 C. Degradation rate constants are calculated from novel equations incorporating IV. Results show that the thermal degradation rate constants of the amorphous PLA and its composites are lower than those of the semicrystalline PLA and its composites due to the …
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A Conductometric Study of the Reaction Velocities of 2, 4-Dinitrochloro, Bromo, and Iodobenzene with Piperidine in Dimethylsulfoxide at Various Concentrations and Temperatures
… of reaction aliquots. Significant reaction rate increases have been observed for certain reaction types when protic solvents are replaced with dipolar aprotic solvents, which are not readily explainable in terms of such physical properties as dielectric constant. Since data in dipolar …
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Kinetics of base-catalyzed isomerization and hydration of butadiene sulfones
… respect to base, and second-order overall. The rate constants and relative rate constants of this reaction system have been obtained in the range of 35 to 55° C. The thermodynamic quantities of the reversible isomerization of β-butadiene sulfone to a-butadiene sulfone have been evaluated. The …
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Effects of Surface Roughness on the Indoor Particle Deposition Rate Constant
… of this work was to quantify the deposition rate constants of size-classified particles on typical indoor surface materials as affected by the degree of surface roughness. The experiments were conducted in a small-scale acrylic chamber. The particle size range was from 0.723 to 5.048 £gm with …
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Proton-coupled electron transfer in molecular and material catalysis
… is important for the calculation of PCET rate constants. The rate constants and kinetic isotope effects for concerted PCET in a set of hydroquinone derivatives are calculated and analyzed in comparison with experimental data.
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The Reaction Kinetics of Neutral Free Radicals and Radical Ions Studied by Laser Flash Photolysis
… systems. In addressing this concern, absolute rate constants and Arrhenius parameters for hydrogen abstraction by t-butoxyl radical were measured for a broad class of substrates including amines, hydrocarbons, and alcohols using laser flash photolysis. Initially, no obvious reactivity …
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Marcus Theory Applied To Acetal Cleavage And Aldol Reactions
… The specific acid catalyzed and uncatalyzed rate constants for hydrolysis are for DMOP k{dollar}rmsb{lcub}H+{rcub}=(2.5pm0.3)times10sp3 Msp{lcub}-1{rcub}ssp{lcub}-1{rcub}, ksb w=(3.6pm0.2)times10sp{lcub}-8{rcub} ssp{lcub}-1{rcub}, ksb{lcub}OH-,E2{rcub}=(2.8pm0.4)times10sp{lcub}-8{rcub} …
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An investigation of phase transfer catalysis employing quantitative structure-activity relationships
… sum of the interfacial adsorption and desorption rate constants. This hypothesis was tested by comparing the rate constants for the stoichiometric alkylation of quaternary ammonium phenoxides to the catalytic rate constants for a series of Td symmetric homologous. It is suggested that the …
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Predicting Kinetics of Spin-Dependent Reactions in an External Magnetic Field with Nonadiabatic Statistical Theory
… complex, revealing a notable increase in the rate constants under strong field conditions. We also discuss different theoretical approaches for calculating spin-orbit coupling (SOC) that mediates transitions between electronic states with different spin multiplicities. The introduced …
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Mitigating and exploiting stochasticity in the immune system
… is of great importance that T cells respond accurately to very small traces of pathogenic signal in a background sea of healthy cells, to which mounting an immune response in the absence of viral infection could prove fatal for the organism. T cells detect pathogenic signal through noisy protein …
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Separation and Characterization of Unknown Halogenated Disinfection by -Products in Drinking Water
… relationships, the decomposition rate constants of six iodinated trihaloacetic acids were estimated. It is quite likely that dichloroiodoacetic acid and bromochloroiodoacetic acid may be found in some drinking waters.
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Bromamine Decomposition and Cyanogen Bromide Formation in Drinking Water From Monobromamine and Formaldehyde
… reaction. The equilibrium and second order rate constants are 2.5 x 105 M-1 and 6.3 x 104 M-1s-1, respectively. (Abstract shortened by UMI.).
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