Sequential Two (Blue) Photon Absorption by NO2in the Presence of H2as a Source of OH in Pulsed Photolysis Kinetic Studies:  Rate Constants for Reaction of OH with CH3NH2, (CH3)2NH, (CH3)3N, and C2H5NH2at 295 K

1998 ◽  
Vol 102 (42) ◽  
pp. 8131-8141 ◽  
Author(s):  
S. A. Carl ◽  
J. N. Crowley
Keyword(s):  
Rate Constants ◽  
Kinetic Studies ◽  
Photon Absorption ◽  
Pulsed Photolysis

Kinetic Studies on Antibody–Hapten Reactions. II. Reactions with Antibodies and their Polypeptide Chains

1973 ◽  
Vol 51 (10) ◽  
pp. 1355-1364 ◽  
Author(s):  
K. A. Kelly ◽  
A. H. Sehon ◽  
A. Froese
Keyword(s):  
Thin Layer ◽  
Rate Constant ◽  
Rate Constants ◽  
Kinetic Studies ◽  
Light Chains ◽  
Gel Chromatography ◽  
Equilibrium Studies ◽  
Polypeptide Chains

Kinetic and equilibrium studies were performed on the reactions of the hapten ε-dinitrophenyl-lysine with specific intact antibodies, reduced, alkylated, and polyalanylated antibodies, and reduced, alkylated, and polyalanylated γ-chains. No reaction was detected between the hapten and light chains. The γ-chains were found to have 0.5 combining sites per chain, and thin layer gel chromatography revealed that they existed as monomers. The rate constant of association for the reaction of γ-chains with hapten was found to be almost 1000 times lower than that for the corresponding reaction with the parent antibody. Differences in the rate constants of dissociation were much less pronounced. These results suggested that the combining site in the separated γ-chain had undergone a change in conformation.

Kinetics of the Ozonation of Tetrabromobisphenol-A in Wastewater

2011 ◽  
Vol 383-390 ◽  
pp. 2945-2950 ◽  
Author(s):  
Jie Zhang ◽  
Shi Long He ◽  
Mei Feng Hou ◽  
Li Ping Wang ◽  
Li Jiang Tian
Keyword(s):  
Rate Constants ◽  
Apparent Rate Constant ◽  
Reaction Rate ◽  
Batch Reactor ◽  
Kinetic Studies ◽  
Tetrabromobisphenol A ◽  
First Order ◽  
Reaction Rate Constants ◽  
Pseudo First Order ◽  
Kinetics Of

The kinetics of TBBPA degradation by ozonation in semi-batch reactor was studied. The reaction rate constants of TBBPA with O3 and •OH were measured by means of direct ozone attack and competition kinetics, and the values of which were 6.10 l/(mol•s), 4.8×109 l/(mol•s), respectively. Results of kinetic studies showed that TBBPA degradation by ozonation under the different conditions tested followed the pseudo-first-order. The values of apparent rate constant of TBBPA degradation increased with the increase of ozone dosage and pH, but decreased with the increase of initial TBBPA concentration.

KINETIC STUDIES OF METHYL-BIS-β-CHLOROETHYLAMINE: III. THE KINETICS OF THE DIMERIZATION IN METHANOL

1948 ◽  
Vol 26b (2) ◽  
pp. 175-180 ◽  
Author(s):  
C. A. Winkler ◽  
A. W. Hay ◽  
A. L. Thompson
Keyword(s):  
Rate Constants ◽  
Initial Rate ◽  
Kinetic Studies ◽  
First Order ◽  
Rate Expression ◽  
Principal Reaction ◽  
Kinetics Of ◽  
Rate Controlling Step

The principal reaction of methyl-bis-β-chloroethylamine in methanol is dimerization, which results in one chlorine from each molecule becoming ionic, but this is accompanied by slight alcoholysis. The rate-controlling step is believed to be the first order formation of an ethylenimonium ion which reacts rapidly with one of its kind to form dimer. The rate expression as calculated from initial rate constants is k (initial) = 4.0 × 1013e−19600/RThr.−1.

An Electron Spin Resonance Study of Some Reactions of Pentafluorosulfuranyl (SF5)

1975 ◽  
Vol 53 (16) ◽  
pp. 2361-2364 ◽  
Author(s):  
John Charles Tait ◽  
James Anthony Howard
Keyword(s):  
Electron Spin Resonance ◽  
Electron Spin ◽  
Rate Constants ◽  
Arrhenius Equation ◽  
Kinetic Studies ◽  
Electron Spin Resonance Study ◽  
Order Process ◽  
First Order ◽  
Spin Resonance ◽  
Spin Resonance Study

A kinetic electron spin resonance study of the self-reaction of SF5 and a spectroscopic and kinetic e.s.r. study of the reaction of SF5 with 1,1-di-t-butylethylene are reported. This radical undergoes self-reaction by a second-order process and the rate constants are given by the Arrhenius equation log 2k1(M−1 s−1) = (10.3 ± 0.5) − (1.7 ± 0.5)/θ where θ = 2.303RT kcal mol−1. It adds to 1,1-di-t-butylethylene to give (t-Bu)2CCH2SF5 which decomposes by a first-order process with rate constants that obey the expression log k2(s−1) = (13 ± 0.4) − (10 ± 0.2)/θ. Both these rate constants are pertinent to kinetic studies of the photoinduced addition of SF5C1 to olefins.

scholarly journals Nitrogenase of Klebsiella pneumoniae. Kinetic studies on the Fe protein involving reduction by sodium dithionite, the binding of MgADP and a conformation change that alters the reactivity of the 4Fe-4S centre

1987 ◽  
Vol 246 (2) ◽  
pp. 455-465 ◽  
Author(s):  
G A Ashby ◽  
R N F Thorneley
Keyword(s):  
Klebsiella Pneumoniae ◽  
Rate Constants ◽  
Protein Conformation ◽  
Kinetic Studies ◽  
Sodium Dithionite ◽  
Conformation Change ◽  
Fe Protein ◽  
Redox Active ◽  
Dithionite Ion ◽  
Kinetics Of

The kinetics of reduction of indigocarmine-dye-oxidized Fe protein of nitrogenase from Klebsiella pneumoniae (Kp2ox) by sodium dithionite in the presence and absence of MgADP were studied by stopped-flow spectrophotometry at 23 degrees C and at pH 7.4. Highly co-operative binding of 2MgADP (composite K greater than 4 × 10(10) M-2) to Kp2ox induced a rapid conformation change which caused the redox-active 4Fe-4S centre to be reduced by SO2-.(formed by the predissociation of dithionite ion) with k = 3 × 10(6) M-1.s-1. This rate constant is at least 30 times lower than that for the reduction of free Kp2ox (k greater than 10(8) M-1.s-1). Two mechanisms have been considered and limits obtained for the rate constants for MgADP binding/dissociation and a protein conformation change. Both mechanisms give rate constants (e.g. MgADP binding 3 × 10(5) less than k less than 3 × 10(6) M-1.s-1 and protein conformation change 6 × 10(2) less than k less than 6 × 10(3) s-1) that are similar to those reported for creatine kinase (EC 2.7.3.2). The kinetics also show that in the catalytic cycle of nitrogenase with sodium dithionite as reductant replacement of 2MgADP by 2MgATP occurs on reduced and not oxidized Kp2. Although the Kp2ox was reduced stoichiometrically by SO2-. and bound two equivalents of MgADP with complete conversion into the less-reactive conformation, it was only 45% active with respect to its ability to effect MgATP-dependent electron transfer to the MoFe protein.

scholarly journals Kinetic and Thermodynamics of Adsorption of Heavy Metals from Spent Automobile Engine Oil onto Activated Carbon from Thevetia peruviana

2019 ◽  
Vol 1 ◽  
pp. 167-175
Author(s):  
L Leke ◽  
T H Dekaa ◽  
S O Olawuyi ◽  
F O Nwosu
Keyword(s):  
Heavy Metals ◽  
Free Energy ◽  
Activated Carbon ◽  
Rate Constants ◽  
Kinetic Studies ◽  
Engine Oil ◽  
Thermodynamic Studies ◽  
Thevetia Peruviana ◽  
Dry Ashing ◽  
Gibb’S Free Energy

The presence of heavy metals was analysed from oil samples employing the dry ashing method. The specific densities and viscosities of the spent and virgin AZ oil samples were determined and found to be 0.9230, 0.9501 and 70.27, 73.27cP respectively. Kinetic and thermodynamic studies of the adsorption of lead (Pb) and chromium (Cr) from the spent oil was also investigated. The spent oil samples were digested and mixed with methyl isobutyl ketone (MIBK), agitated with activated carbon produced from Thevetia peruviana (bush milk) shells at various contact times of 2, 4, 5, 10, 15, 20, 30, 40, 50, 60, 90 and 120 minutes. Kinetic studies revealed that for lead (Pb), the rate constants were found to be 0.044, 0.060 and 0.067 ppm/min at 27oC, 35 oC and 45 oC, respectively, while higher values or rate constants of 0.126, 0.127 and 0,168 ppm/min were observed at 27 oC, 35 oC and 45 oC, respectively, for chromium (Cr). For the thermodynamic studies the Gibb's free energy (ΔG) values were; –1.29, -1.61 and –1.82 KJmol-1at 27 oC, 35 oC and 45 oC, respectively, indicating spontaneity. However, the Gibb's free energy (ΔG) for chromium showed +0.050, -2.13 and -2.14 KJmol-1at 27 oC, 35 oC and 45 oC, indicating non-spontaneity at 27 oC. The positive values of ΔS for both metals with Pb (21 - 30 Jmol-1) and Cr (695 – 1867 Jmol-1 ) indicated that the metals were dissociatively adsorbed onto the adsorbent while for the E values, Cr (8 – 61 KJmol-1) had a higher than with Pb (6 – 35 KJmol-1) further explaining the non-spontaneity of the process for Cr at some reaction condition.

EFFECT OF CACL2 ON ANTI-Xa ACTIVITIES OF HEPARIN AND LMW HEPARINS

1987 ◽  
Author(s):  
T W Barrowcliffe ◽  
Yvonne Le Shirley
Keyword(s):  
Unfractionated Heparin ◽  
Rate Constants ◽  
Differential Effect ◽  
Gel Filtration ◽  
Kinetic Studies ◽  
Standard Addition ◽  
High Affinity ◽  
At Iii ◽  
Ca Ions ◽  
Heparin Fractions

Assays of anti-Xa activity of heparin are generally carried out using plasma or AT III, in the absence of Ca++ ions. We studied the effect of physiological (3 mM) Ca++ on the relative anti-Xa activities of heparin and LMW heparin, using human AT III, bovine Xa and S-2222.Potencies of a LMW heparin standard vs. the International Standard (IS) for unfractionated heparin (UEH) were decreased by 45% in the presence of CaCl2. This was shown to be due to a differential effect of CaCl2 on the two substances, with a 93% potentiation in activity of the UEH standard, and only 7% increase for the LMW standard. Addition of CaCl2 to 8 other LMtf heparins gave increases in anti-Xa activity ranging from 0 to 60%. Studies on heparin fractions ranging from 4,000 to 30,000 M.Wt., prepared by gel filtration, showed that a minimum M.Wt. of > 6,000 is required for CaCl2 potentiation of anti-Xa activity.In kinetic studies, the influence of UEH on second order rate constants was increased by 55% in the presence of CaCl2. However, CaCl2 had no effect on the rate enhancement by three high-affinity oligosaccharides, of 5, 10 and 20 saccharide units.These studies show that the effect of CaCl2 on the anti-Xa activity of heparin is highly dependent on M.Wt. Anti-Xa activities of LMW heparins determined in the absence of CaCl2 could be misleading.

Direct detection of methylphenylgermylene and 1,2-dimethyl-1,2-diphenyldigermene — Kinetic studies of their reactivities in solution

2006 ◽  
Vol 84 (7) ◽  
pp. 934-948 ◽  
Author(s):  
William J Leigh ◽  
Ileana G Dumbrava ◽  
Farahnaz Lollmahomed
Keyword(s):  
Acetic Acid ◽  
Rate Constants ◽  
Flash Photolysis ◽  
Laser Flash Photolysis ◽  
Direct Detection ◽  
Kinetic Studies ◽  
Laser Flash ◽  
Absolute Rate ◽  
Hydrocarbon Solvents ◽  
Diffusion Controlled

Photolysis of 1,3,4-trimethyl-1-phenylgermacyclopent-3-ene (5) in hydrocarbon solvents containing isoprene, methanol, or acetic acid affords 2,3-dimethyl-1,3-butadiene (DMB) and the expected trapping products of methyl phenylgermylene (GeMePh) in chemical yields exceeding 90%. The germylene has been detected in hexane solution by laser flash photolysis as a short-lived species (τ ~ 2 µs) exhibiting a UV-vis absorption spectrum centered at λmax = 490 nm. It decays with second-order kinetics and a rate constant close to the diffusion-controlled limit, with the concomitant growth of a second longer-lived transient (λmax = 420 nm) that is assigned to a mixture of (E)- and (Z)-1,2-dimethyl-1,2-diphenyldigermene (4). Absolute rate constants have been determined for the reactions of the germylene with primary and tertiary amines (n-BuNH2 and Et3N, respectively), acetic acid (AcOH), a terminal alkyne and alkene, isoprene, DMB, CCl4, and the group 14 hydrides Et3SiH and Bu3SnH. GeMePh is slightly more reactive than GePh2 towards all the reagents studied in this work; both are significantly less reactive than GeMe2 toward the same substrates. Absolute rate constants for the reactions of 4 have also been measured or assigned upper limits in every case and are compared to previously reported values for tetraphenyl- and tetramethyl-digermene with the same reagents.Key words: germylene, digermene, kinetics, laser flash photolysis, germirane, germirene, vinylgermirane, complex, UV–vis spectrum, insertion, addition.

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