scholarly journals THE APPARATUS ARRANGEMENT AND REGIME PARAMETERS FOR ISOPRENE POLYMERIZATION PROCESS IN BULK

2021 ◽  
Vol 58 ◽  
pp. 66-69
Author(s):  
Olga V. Gilevskaya ◽  
◽  
Yury P. Yulenets ◽  
Keyword(s):  
Polymerization Process ◽  
Bed Height ◽  
Stepwise Increase ◽  
The One ◽  
Isoprene Polymerization

The stationary bed type regimes of apparatuses for catalytic isoprene polymerization process in bulk are investigated. If the polymerization process is performed with the bed height equal to 3 mm, the thermal apparatus regime is close to isothermic one. The increase of the bed height up to 6 mm makes the apparatus regime wide of the mark. To remove the lack there is proposed the regime providing the one time stepwise increase of the wall apparatus temperature. Due to proposed regime the apparatus efficiency makes gain while polymerization is performed up to incomplete conversions

The Effects of Amines on the Esterase Activities of Thrombin and Thrombokinase and on Several Clotting Tests

1974 ◽  
Vol 31 (02) ◽  
pp. 309-318
Author(s):  
Phyllis S Roberts ◽  
Raphael M Ottenbrite ◽  
Patricia B Fleming ◽  
James Wigand
Keyword(s):  
Choline Chloride ◽  
Polymerization Process ◽  
Ammonium Bromide ◽  
Bovine Thrombin ◽  
One Stage ◽  
Human Proteins ◽  
Rate Of Hydrolysis ◽  
The One ◽  
Hydrolysis Of Esters ◽  
Hydrolysis Of

Summary1. Choline chloride, 0.1 M (in 0.25 M Tris. HCl buffer, pH 7.4 or 8.0, 37°), doubles the rate of hydrolysis of TAME by bovine thrombokinase but has no effect on the hydrolysis of this ester by either human or bovine thrombin. Only when 1.0 M or more choline chloride is present is the hydrolysis of BAME by thrombokinase or thrombin weakly inhibited. Evidence is presented that shows that these effects are due to the quaternary amine group.2. Tetramethyl ammonium bromide or chloride has about the same effects on the hydrolysis of esters by these enzymes as does choline chloride but tetra-ethyl, -n.propyl and -n.butyl ammonium bromides (0.1 M) are stronger accelerators of the thrombokinase-TAME reaction and they also accelerate, but to a lesser degree, the thrombin-TAME reaction. In addition, they inhibit the hydrolysis of BAME by both enzymes. Their effects on these reactions, however, do not follow any regular order. The tetraethyl compound is the strongest accelerator of the thrombokinase-TAME reaction but the tetra-ethyl and -butyl compounds are the strongest accelerators of the thrombin-TAME reaction. The ethyl and propyl compounds are the best (although weak) inhibitors of the thrombokinase-BAME and the propyl compound of the thrombin-BAME reactions.3. Tetra-methyl, -ethyl, -n.propyl and -n.butyl ammonium bromides (0.01 M) inhibit the clotting of fibrinogen by thrombin (bovine and human proteins) at pH 7.4, imidazole or pH 6.1, phosphate buffers and they also inhibit, but to a lesser degree, a modified one-stage prothrombin test. In all cases the inhibition increases regularly as the size of the alkyl group increases from methyl to butyl. Only the ethyl com pound (0.025 M but not 0.01 M), however, significantly inhibits the polymerization of bovine fibrin monomers. It was concluded that inhibition of the fibrinogen-thrombin and the one-stage tests by the quaternary amines is not due to any effect of the com pounds on the polymerization process but probably due to inhibition of thrombin’s action on fibrinogen by the quaternary amines.

scholarly journals Periodic Polymerization and the Generation of Polymer Giant Vesicles Autonomously Driven by pH Oscillatory Chemistry

2021 ◽  
Vol 9 ◽  
Author(s):  
Jinshan Guo ◽  
Eszter Poros-Tarcali ◽  
Juan Pérez-Mercader
Keyword(s):  
Self Assembly ◽  
Morphological Evolution ◽  
Polymerization Process ◽  
Giant Vesicles ◽  
One Pot ◽  
Continuous Increase ◽  
Responsive Materials ◽  
Complex Processes ◽  
The One ◽  
Semibatch Reactor

Using the radicals generated during pH oscillations, a semibatch pH oscillator is used as the chemical fuel and engine to drive polymerization induced self-assembly (PISA) for the one-pot autonomous synthesis of functional giant vesicles. Vesicles with diameters ranging from sub-micron to ∼5 µm are generated. Radical formation is found to be switched ON/OFF and be autonomously controlled by the pH oscillator itself, inducing a periodic polymerization process. The mechanism underlying these complex processes is studied and compared to conventional (non-oscillatory) initiation by the same redox pair. The pH oscillations along with the continuous increase in salt concentration in the semibatch reactor make the self-assembled objects undergo morphological evolution. This process provides a self-regulated means for the synthesis of soft giant polymersomes and opens the door for new applications of pH oscillators in a variety of contexts, from the exploration of new geochemical scenarios for the origin of life and the autonomous emergence of the necessary free-energy and proton gradients, to the creation of active functional microreactors and programmable release of cargo molecules for pH-responsive materials.

Effects of Synthesis-Solvent on Characteristics of Poly(N-Isopropylacrylamide) Hydrogels Synthesized by Frontal Polymerization

2011 ◽  
Vol 295-297 ◽  
pp. 1193-1197 ◽  
Author(s):  
Qiao Feng ◽  
Ling Zhi Du ◽  
Qing Zhi Yan ◽  
Chang Chun Ge
Keyword(s):  
Mixed Solvent ◽  
Mixed Solvents ◽  
Frontal Polymerization ◽  
Swelling Behavior ◽  
Polymerization Process ◽  
Swelling Ratio ◽  
The One ◽  
Short Time ◽  
Responsive Hydrogels

The synthesis of thermo-responsive hydrogels poly(N-isopropylacrylamide )(PNIPAm) by frontal polymerization (FP) was carried out in four mixed solvents, i.e. dimethylsulfoxide (DMSO) mixing with water, ethanol, tetrahydrofuran (THF) and acetone, respectively. The influences of mixed solvent on frontal parameters, pore morphologies, swelling behavior of PNIPAm hydrogels were investigated. The pore of PNIPAm hydrogel synthesized in THF/DMSO was observed a big honeycomb cells, others were channel-like cells. Furthermore, the sample obtained in THF/DMSO had higher swelling ratio as compared to others, and the one synthesized in Water/DMSO showed the lowest. Above results indicated that fine-tuned poly(N-isopropylacrylamide) hydrogels can be prepared in short time and with easy protocol by adjusting mixed solvents in frontal polymerization process.

Experimental Investigation of Sand Bed Height and Wave Height in Gas-Slurry Stratified Flow

2017 ◽  
Author(s):  
Ashwin Padsalgikar ◽  
Ramin Dabirian ◽  
Ram S. Mohan ◽  
Ovadia Shoham
Keyword(s):  
Particle Sizes ◽  
High Concentration ◽  
Pressure Losses ◽  
Bed Height ◽  
Oil And Natural Gas ◽  
Solid Transport ◽  
Gas Liquid Flow ◽  
The One ◽  
Superficial Gas Velocity ◽  
Sand Beds

Unconsolidated reservoirs are notorious for production of sand with crude oil and natural gas. Bed formation in production pipelines poses several operational problems, such as partial or complete pipeline blockage, which decreases production rate and increases frictional pressure losses. Equipment failure may occur as well as erosion/corrosion and formation of corrosive cells under the sand beds. In this study, solid transport in horizontal stratified gas-liquid flow is investigated for a high concentration of 20,000 PPM, leading to sand bed formation. The experiments are conducted with air and water along with glass bead with particle sizes of 45–90 μm and 425–600 μm. The sand bed formation is studied by conducting experiments with gas-slurry flow. The experimental results confirm that the height of the bed decreases with increasing superficial gas velocity, and increases with increasing superficial liquid velocities. It is also observed that the height of the bed created with smaller diameter particles is larger than the one created by the bigger. The acquired experimental data shed more light on the formation of sand beds. It also serves as a basis for theoretical mechanistic models to enable prediction and design of stratified gas-liquid-solid flow.

scholarly journals Building a model of the isoprene polymerization process in the presence of microheterogeneous neodimiumcatalytic systems

2019 ◽  
Vol 282 ◽  
pp. 012030
Author(s):  
Eldar Miftakhov ◽  
Sofya Mustafina ◽  
Olga Medvedeva ◽  
Dmitriy Zhavoronkov ◽  
Svetlana Mustafina
Keyword(s):  
Polymerization Process ◽  
Isoprene Polymerization

Note on Selection of Coordinate Systems for Geodynamics

1975 ◽  
Vol 26 ◽  
pp. 395-407
Author(s):  
S. Henriksen
Keyword(s):  
Sea Level ◽  
The Other ◽  
Coordinate Systems ◽  
Mean Sea Level ◽  
The Earth ◽  
The One ◽  
Static Systems ◽  
Selection Of

The first question to be answered, in seeking coordinate systems for geodynamics, is: what is geodynamics? The answer is, of course, that geodynamics is that part of geophysics which is concerned with movements of the Earth, as opposed to geostatics which is the physics of the stationary Earth. But as far as we know, there is no stationary Earth – epur sic monere. So geodynamics is actually coextensive with geophysics, and coordinate systems suitable for the one should be suitable for the other. At the present time, there are not many coordinate systems, if any, that can be identified with a static Earth. Certainly the only coordinate of aeronomic (atmospheric) interest is the height, and this is usually either as geodynamic height or as pressure. In oceanology, the most important coordinate is depth, and this, like heights in the atmosphere, is expressed as metric depth from mean sea level, as geodynamic depth, or as pressure. Only for the earth do we find “static” systems in use, ana even here there is real question as to whether the systems are dynamic or static. So it would seem that our answer to the question, of what kind, of coordinate systems are we seeking, must be that we are looking for the same systems as are used in geophysics, and these systems are dynamic in nature already – that is, their definition involvestime.

Nucleation of Disorder in Fe3Al Alloys

1967 ◽  
Vol 25 ◽  
pp. 312-313
Author(s):  
P. R. Swann ◽  
W. R. Duff ◽  
R. M. Fisher
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Annealing Temperature ◽  
Antiphase Domain ◽  
Effect Of Temperature ◽  
Domain Structures ◽  
Transmission Electron ◽  
Domain Boundaries ◽  
Higher Temperature ◽  
The One

Recently we have investigated the phase equilibria and antiphase domain structures of Fe-Al alloys containing from 18 to 50 at.% Al by transmission electron microscopy and Mössbauer techniques. This study has revealed that none of the published phase diagrams are correct, although the one proposed by Rimlinger agrees most closely with our results to be published separately. In this paper observations by transmission electron microscopy relating to the nucleation of disorder in Fe-24% Al will be described. Figure 1 shows the structure after heating this alloy to 776.6°C and quenching. The white areas are B2 micro-domains corresponding to regions of disorder which form at the annealing temperature and re-order during the quench. By examining specimens heated in a temperature gradient of 2°C/cm it is possible to determine the effect of temperature on the disordering reaction very precisely. It was found that disorder begins at existing antiphase domain boundaries but that at a slightly higher temperature (1°C) it also occurs by homogeneous nucleation within the domains. A small (∼ .01°C) further increase in temperature caused these micro-domains to completely fill the specimen.

Fundamental Research into Thin Films in a Developing Country

1972 ◽  
Vol 30 ◽  
pp. 500-501
Author(s):  
J.A. Eades ◽  
E. Grünbaum
Keyword(s):  
Thin Films ◽  
Growth Process ◽  
Empirical Process ◽  
Nucleation And Growth ◽  
Research Groups ◽  
Film Research ◽  
Fundamental Research ◽  
Controlled Deposition ◽  
The One ◽  
The University

In the last decade and a half, thin film research, particularly research into problems associated with epitaxy, has developed from a simple empirical process of determining the conditions for epitaxy into a complex analytical and experimental study of the nucleation and growth process on the one hand and a technology of very great importance on the other. During this period the thin films group of the University of Chile has studied the epitaxy of metals on metal and insulating substrates. The development of the group, one of the first research groups in physics to be established in the country, has parallelled the increasing complexity of the field.The elaborate techniques and equipment now needed for research into thin films may be illustrated by considering the plant and facilities of this group as characteristic of a good system for the controlled deposition and study of thin films.

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