Estimation of the electron-collision initiation rate constant for the plasma polymerization and deposition of ethane using a transport-based model

1992 ◽  
Vol 12 (4) ◽  
pp. 551-563 ◽  
Author(s):  
John R. Jensen ◽  
Kenneth A. Solen
Keyword(s):  
Rate Constant ◽  
Plasma Polymerization ◽  
Electron Collision ◽  
Initiation Rate

scholarly journals Rate constant of the reaction of the peroxyl radical of 1,4-dioxane with α-Tocopherol and trolox

2020 ◽  
Vol 64 (11) ◽  
pp. 55-60
Author(s):  
Olesya V. Semikasheva ◽  
◽  
Lucia R. Yakupova ◽  
Rustam L. Safiullin ◽  
◽  
...  
Keyword(s):  
Induction Period ◽  
Rate Constant ◽  
Peroxyl Radical ◽  
Practical Interest ◽  
Water Soluble ◽  
Oxygen Absorption ◽  
Initiation Rate ◽  
Radical Chain ◽  
Decay Rate Constant ◽  
Integral Methods

The study of the properties of water-soluble antioxidants is of practical interest. Research is hindered by the fact that such substances are poorly soluble in substrates, which are most widespread in determining the quantitative characteristics of antioxidants. Usually it is cumene, ethylbenzene, styrene. In this work, we used a method based on a model reaction of the radical chain 1,4-dioxane oxidation. This substrate is the most suitable solvent for evaluating the water-soluble substances antioxidant activity. The inhibitory activity of α-tocopherol (vitamin E) and trolox (a water-soluble analogue of α-tocopherol) was studied in a model system of radical chain 1,4-dioxane oxidation. Air oxygen served as the oxidizing agent. The experiments were carried out at 333 K. Initiation was carried out with 2,2'-azo-bis-isobutyronitrile. The reaction kinetics was monitored by the rate of oxygen uptake using a manometric setup. In this work to measure the initiation rate, the inhibitors method is used. The standard α-tocopherol inhibitor was used for this purpose. α-Tocopherol is an effective inhibitor with a known stoichiometric inhibition ratio of two. The method used in our study makes it possible to measure correct the length of the induction period using the kinetics of oxygen absorption. The induction period was determined by graphical and integral methods. The initiation rate was calculated based on the induction period values. The resulting value is in satisfactory agreement with the data based on the literary value of the decay rate constant 2,2'-azo-bis-isobutyronitrile. The rate constant of the reaction of the 1,4-dioxane peroxyl radical with α-tocopherol and trolox (fk7, L mol-1s-1, 333 K) was measured: (1.6 ± 0.1)∙106, (1.2 ± 0.1)∙106. The stoichiometric inhibition coefficient for trolox in the system of radical chain 1,4-dioxane oxidation was determined: f = 2.4 ± 0.2.

The initiation of styrene polymerization by phenyl titanium tri iso propoxide and titanous tri iso propoxide

1960 ◽  
Vol 254 (1278) ◽  
pp. 408-424 ◽  
Keyword(s):  
Free Radicals ◽  
Rate Constant ◽  
Radical Reaction ◽  
Kinetic Scheme ◽  
Free Radical Reaction ◽  
Styrene Polymerization ◽  
Initiation Rate ◽  
First Order ◽  
Titanium Compound ◽  
Rate Of Polymerization

The polymerization of styrene initiated by phenyl titanium tri iso propoxide has been found to be a free-radical reaction in the region 15 to 50 °C. The photosensitized decomposition of this compound is a first-order reaction yielding free radicals and titanous triisopropoxide. In absence of illumination the presence of titanous triisopropoxide is also necessary to initiate polymerization. The overall rate of polymerization has been found to be expressed by an equation of the form R p = k p k i 1/2 / k i 1/2 [ M ] 3/2 [ Ti ] 1/2 , where the rate constants have their usual significance and [ Ti ] is the concentration of either phenyl titanium triisopropoxide or titanous triisopropoxide, whichever is present in smaller concentration. A kinetic scheme has been presented in which initiation is effected by reaction of monomer with a 1:1 complex of three- and four-valent titanium . The initiation rate constant k i has been evaluated as 7·7 ± 0·2 x 10 -7 mole/l, s, and is constant over the temperature range studied. Titanous tri iso propoxide also undergoes a termination reaction with free radicals resulting in a four-valent titanium compound. The rate constant for this reaction has been evaluated as 4·0 x 10 6 exp [ — (2·8 kcal/mole)/ RT ] mole 1. -1 s -1 .

Reassessment of the rate constant for electron collision quenching of KrF(B)

1989 ◽  
Vol 55 (24) ◽  
pp. 2482-2484 ◽  
Author(s):  
Mark J. Kushner ◽  
David E. Hanson ◽  
Barry I. Schneider
Keyword(s):  
Rate Constant ◽  
Electron Collision

scholarly journals Simultaneous pharmacodynamic analysis of the lag and bactericidal phases exhibited by beta-lactams against Escherichia coli.

1996 ◽  
Vol 40 (10) ◽  
pp. 2306-2310 ◽  
Author(s):  
R C Li
Keyword(s):  
Escherichia Coli ◽  
Rate Constant ◽  
Morphological Changes ◽  
Penicillin G ◽  
Beta Lactams ◽  
Initiation Rate ◽  
Bacterial Killing ◽  
Modeling Approach ◽  
Induction Rate ◽  
Lag Period

Antibiotic-bacterium interactions are complex in nature. In many cases, bacterial killing does not commence immediately after the addition of an antibiotic, and a lag period is observed. Antibiotic permeation and/or the intermediate steps that exist between antibiotic-receptor binding and expression of cell death are two major possible causes for such lag period. This study was primarily designed to determine the relationship, if any, between antibiotic concentrations and the lag periods by a modeling approach. Short-term time-kill studies were conducted for amoxicillin, ampicillin, penicillin-G, oxacillin, and dicloxacillin against Escherichia coli. In conjunction with the use of a saturable rate model to describe the concentration-dependent killing process, a first-order induction (initiation) rate constant was used to characterize the delay in bacterial killing during the lag period. For all of the beta-lactams tested, parameters describing the bactericidal effect suggest that amoxicillin and ampicillin were much more potent than oxacillin and dicloxacillin. The induction rate constant estimates for both ampicillin and amoxicillin were found to relate linearly to concentrations. Nevertheless, these induction rate constant estimates were lower for penicillin-G, oxacillin, and dicloxacillin and increased nonlinearly with concentrations until an apparent plateau was observed. These findings support the hypothesis that the permeation process is potentially a rate-limiting step for the rapid bactericidal beta-lactams such as ampicillin and amoxicillin. However, as suggested by previous observations of the various morphological changes induced by beta-lactams, the contribution of the steps following antibiotic-receptor complex formation to the lag period might be significant for the less bactericidal antibiotics such as oxacillin and dicloxacillin. Findings from the present modeling approach can potentially be used to guide future bench experimentation.

New replica method with plasma polymerized film by glow discharge

1988 ◽  
Vol 46 ◽  
pp. 414-415
Author(s):  
A. Tanaka ◽  
M. Yamaguchi ◽  
T. Hirano
Keyword(s):  
Power Supply ◽  
Plasma Polymerization ◽  
Vacuum Chamber ◽  
Complex Surface ◽  
Replica Method ◽  
Metal Extraction ◽  
High Voltage Power Supply ◽  
Negative Glow ◽  
Hydrocarbon Gas ◽  
Hydrocarbon Molecules

The plasma polymerization replica method and its apparatus have been devised by Tanaka (1-3). We have published several reports on its application: surface replicas of biological and inorganic specimens, replicas of freeze-fractured tissues and metal-extraction replicas with immunocytochemical markers.The apparatus for plasma polymerization consists of a high voltage power supply, a vacuum chamber containing a hydrocarbon gas (naphthalene, methane, ethylene), and electrodes of an anode disk and a cathode of the specimen base. The surface replication by plasma polymerization in negative glow phase on the cathode was carried out by gassing at 0.05-0.1 Torr and glow discharging at 1.5-3 kV D.C. Ionized hydrocarbon molecules diffused into complex surface configurations and deposited as a three-dimensionally polymerized film of 1050 nm in thickness.The resulting film on the complex surface had uniform thickness and showed no granular texture. Since the film was chemically inert, resistant to heat and mecanically strong, it could be treated with almost any organic or inorganic solvents.

Three-Dimensional Immunoelectron Microscopy of Yeast Cells by a New High-Resolution Replica Method

1985 ◽  
Vol 43 ◽  
pp. 562-563
Author(s):  
Hirano T. ◽  
M. Yamaguchi ◽  
M. Hayashi ◽  
Y. Sekiguchi ◽  
A. Tanaka
Keyword(s):  
High Resolution ◽  
Plasma Polymerization ◽  
Three Dimensional ◽  
Freeze Fracture ◽  
Replica Method ◽  
Yeast Cells ◽  
Dynamic Aspect ◽  
Replica Technique ◽  
Gaseous Hydrocarbon ◽  
Transmission Electron

A plasma polymerization film replica method is a new high resolution replica technique devised by Tanaka et al. in 1978. It has been developed for investigation of the three dimensional ultrastructure in biological or nonbiological specimens with the transmission electron microscope. This method is based on direct observation of the single-stage replica film, which was obtained by directly coating on the specimen surface. A plasma polymerization film was deposited by gaseous hydrocarbon monomer in a glow discharge.The present study further developed the freeze fracture method by means of a plasma polymerization film produces a three dimensional replica of chemically untreated cells and provides a clear evidence of fine structure of the yeast plasma membrane, especially the dynamic aspect of the structure of invagination (Figure 1).

Functional Properties of p-Anisoylated Plasmin-Staphylokinase Complex

1993 ◽  
Vol 70 (02) ◽  
pp. 326-331 ◽  
Author(s):  
H R Lijnen ◽  
B Van Hoef ◽  
R A G Smith ◽  
D Collen
Keyword(s):  
Human Plasma ◽  
Rate Constant ◽  
Time Course ◽  
Bolus Injection ◽  
Similar Rate ◽  
Clot Lysis ◽  
Lag Phase ◽  
Plasma Clot ◽  
Rapid Clearance ◽  
Stoichiometric Complex

SummaryThe kinetic and fibrinolytic properties of a reversibly acylated stoichiometric complex between human plasmin and recombinant staphylokinase (plasmin-STAR complex) were evaluated. The acylation rate constant of plasmin-STAR by p-amidinophenyl-p’-anisate-HCI was 52 M-1 s-1 and its deacylation rate constant 1.2 × 10-4 s-1 (t½ of 95 min) which are respectively 50-fold and around 3-fold lower than for the plasmin-streptokinase complex. The acylated complex was stable as evidenced by binding to lysine-Sepharose. However, following an initial short lag phase, the acylated plasmin-STAR complex activated plasminogen at a similar rate as the unblocked complex, whereas the acylated plasmin-streptokinase complex did not activate plasminogen. These findings indicate that STAR, unlike streptokinase, dissociates from its acylated complex with plasmin in the presence of excess plasminogen. In agreement with this hypothesis, the time course of the lysis of a 125I-fibrin labeled plasma clot submerged in citrated human plasma, is similar for acylated plasmin-STAR, unblocked plasmin-STAR and free STAR (50% clot lysis in 2 h requires 12 nM of each agent). The plasma clearances of STAR-related antigen following bolus injection in hamsters were 1.0 to 1.5 ml/min for acylated plasmin-STAR, unblocked plasmin-STAR and free STAR, as a result of short initial half-lives of 2.0 to 2.5 min.The dissociation of the anisoylated plasmin-STAR complex and its consequent rapid clearance suggest that it has no apparent advantages as compared to free STAR for clinical thrombolysis.

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