scholarly journals Emulsion polymerisation of vinylidene fluoride: Effects of mixing and reaction conditions on the initial rate of polymerisation

2021 ◽  
Author(s):  
Ana Carolina Mendez Ecoscia ◽  
Nida Sheibat‐Othman ◽  
Timothy F. L. McKenna
Keyword(s):  
Vinylidene Fluoride ◽  
Initial Rate ◽  
Reaction Conditions ◽  
Emulsion Polymerisation

Influencing Factors of Modified PVDF Grafted onto a Blended PAMPS(PVDF-G-PAMPS) Membrane

2011 ◽  
Vol 197-198 ◽  
pp. 1267-1270
Author(s):  
Jia Xu ◽  
Gui Bao Guo ◽  
Sheng Li An
Keyword(s):  
Reaction Temperature ◽  
Proton Exchange Membrane ◽  
Vinylidene Fluoride ◽  
Ammonium Persulfate ◽  
Proton Exchange ◽  
Reaction Conditions ◽  
Membrane Conductivity ◽  
Poly Vinylidene Fluoride ◽  
Exchange Membrane ◽  
Optimal Reaction

A proton exchange membrane of blended poly (acrylamido-2- methylpropane sulfonic acid) grafted onto modified poly (vinylidene fluoride) membrane (PVDF-g-PAMPS) was prepared The influences of Na4SiO4 content, reaction temperature and time, content of ammonium persulfate and AMPS on PVDF-g-PAMPS membrane were discussed. The results show that the optimal reaction conditions are as follows: Na4SiO4 is 8%; ammonium persulfate is 0.016 mol / L; AMPS is 30 %; the reaction temperature is 80 °C and the reaction time is 1h. On the condition, PVDF-g-PAMPS membrane conductivity can reach to 1.27×10-2 S/cm.

Surfactant-free preparation of poly(vinylidene fluoride) nanoparticle dispersions and their use as surface coating agents

2018 ◽  
Vol 20 (2) ◽  
pp. 502-505 ◽  
Author(s):  
Hyeon Jun Heo ◽  
In Jun Park ◽  
Sang Goo Lee ◽  
Jong-Wook Ha ◽  
Soo-Bok Lee ◽  
...  
Keyword(s):  
Ethylene Glycol ◽  
Surface Coating ◽  
Vinylidene Fluoride ◽  
Poly Ethylene Glycol ◽  
Fluorinated Surfactants ◽  
Nanoparticle Dispersions ◽  
Emulsion Polymerisation ◽  
Poly Vinylidene Fluoride ◽  
Poly Ethylene ◽  
Coating Agents

Surfactant-free emulsion polymerisation of vinylidene fluoride was performed using poly(ethylene glycol) and a dispersion of poly(vinylidene fluoride) (PVDF) nanoparticles instead of typical fluorinated surfactants.

Effects of two new additives on the initial rate of peroxodisulphate electrosynthesis

1983 ◽  
Vol 48 (7) ◽  
pp. 1956-1962 ◽  
Author(s):  
Jan Balej ◽  
Martin Kadeřávek ◽  
Hermann Matschiner ◽  
Wolfgang Thiele
Keyword(s):  
Initial Rate ◽  
Additive Concentration ◽  
Reaction Conditions ◽  
Maximum Increase ◽  
Ion Formation ◽  
Platinum Anode ◽  
Maximum Current

Two new additives, dipotassium cyanimidodithiocarbonate (DKDK) and 5-thio-2-imido-3,4-disulphazolidine (TIDSAL), were tested for the effect they have on the initial rate of peroxodisulphate ion formation in 5M-H2SO4 solution. The concentrations of the additives ranged from 10-4 to 10-2 mol dm-3. Both substances were found to increase current yields of peroxodisulphates as well as oxygen overpotential on the platinum anode. The additive concentration at which a maximum increase was achieved was about 1 . 10-2 mol dm-3 in both cases. Maximum current yields attained under the applied reaction conditions were, however, somewhat lower than those observed with an optimum addition of SCN-.

scholarly journals New Kinetic Spectrophotometric Method for Determination of Fexofenadine Hydrochloride in Pharmaceutical Formulations

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Safwan Ashour ◽  
Mouhammed Khateeb
Keyword(s):  
Spectrophotometric Method ◽  
Initial Rate ◽  
Pharmaceutical Preparations ◽  
Pharmaceutical Formulations ◽  
Fixed Time ◽  
Official Method ◽  
Reaction Conditions ◽  
Accuracy And Precision ◽  
Kinetic Spectrophotometric

A simple and sensitive kinetic spectrophotometric method was developed for the determination of fexofenadine hydrochloride in bulk and pharmaceutical preparations. The method is based on a kinetic investigation of the oxidation reaction of fexofenadine using alkaline potassium permanganate as an oxidizing agent at room temperature. The reaction is followed spectrophotometrically by measuring the increase of absorbance owing to the formation of manganate ion at 610 nm. The initial rate and fixed time (at 15 min) methods are utilized for construction of calibration graphs. All the reaction conditions for the proposed method have been studied. The linearity range was found to be 2.5–50.0 μg mL−1 with detection limit of 0.055 μg mL−1 for both initial rate and fixed time methods. The proposed method was applied successfully for the determination of fexofenadine in pharmaceutical formulations; the percentage recoveries were 99.98–101.96%. The results obtained were compared statistically with those obtained by the official method and showed no significant differences regarding accuracy and precision.

Undecagold labeling of tRNA

1991 ◽  
Vol 49 ◽  
pp. 44-45
Author(s):  
James F. Hainfeld ◽  
Kyra M. Alford ◽  
Mathias Sprinzl ◽  
Valsan Mandiyan ◽  
Santa J. Tumminia ◽  
...  
Keyword(s):  
High Resolution ◽  
Transmission Electron Micrograph ◽  
Anticodon Loop ◽  
Electron Micrograph ◽  
Reaction Conditions ◽  
Scanning Transmission Electron ◽  
Transmission Electron ◽  
Scanning Transmission

The undecagold (Au11) cluster was used to covalently label tRNA molecules at two specific ribonucleotides, one at position 75, and one at position 32 near the anticodon loop. Two different Au11 derivatives were used, one with a monomaleimide and one with a monoiodacetamide to effect efficient reactions.The first tRNA labeled was yeast tRNAphe which had a 2-thiocytidine (s2C) enzymatically introduced at position 75. This was found to react with the iodoacetamide-Aun derivative (Fig. 1) but not the maleimide-Aun (Fig. 2). Reaction conditions were 37° for 16 hours. Addition of dimethylformamide (DMF) up to 70% made no improvement in the labeling yield. A high resolution scanning transmission electron micrograph (STEM) taken using the darkfield elastically scattered electrons is shown in Fig. 3.

Piezoelectric β-polymorph formation of new textiles by surface modification with coating process based on interfacial interaction on the conformational variation of poly (vinylidene fluoride) (PVDF) chains

2020 ◽  
Vol 91 (3) ◽  
pp. 31301
Author(s):  
Nabil Chakhchaoui ◽  
Rida Farhan ◽  
Meriem Boutaldat ◽  
Marwane Rouway ◽  
Adil Eddiai ◽  
...  
Keyword(s):  
High Efficiency ◽  
Vinylidene Fluoride ◽  
Research Work ◽  
Research Area ◽  
Interfacial Interaction ◽  
Tetraethyl Orthosilicate ◽  
Poly Vinylidene Fluoride ◽  
Carbon Nanofillers ◽  
The Impact ◽  
Advanced Applications

Novel textiles have received a lot of attention from researchers in the last decade due to some of their unique features. The introduction of intelligent materials into textile structures offers an opportunity to develop multifunctional textiles, such as sensing, reacting, conducting electricity and performing energy conversion operations. In this research work nanocomposite-based highly piezoelectric and electroactive β-phase new textile has been developed using the pad-dry-cure method. The deposition of poly (vinylidene fluoride) (PVDF) − carbon nanofillers (CNF) − tetraethyl orthosilicate (TEOS), Si(OCH2CH3)4 was acquired on a treated textile substrate using coating technique followed by evaporation to transform the passive (non-functional) textile into a dynamic textile with an enhanced piezoelectric β-phase. The aim of the study is the investigation of the impact the coating of textile via piezoelectric nanocomposites based PVDF-CNF (by optimizing piezoelectric crystalline phase). The chemical composition of CT/PVDF-CNC-TEOS textile was detected by qualitative elemental analysis (SEM/EDX). The added of 0.5% of CNF during the process provides material textiles with a piezoelectric β-phase of up to 50% has been measured by FTIR experiments. These results indicated that CNF has high efficiency in transforming the phase α introduced in the unloaded PVDF, to the β-phase in the case of nanocomposites. Consequently, this fabricated new textile exhibits glorious piezoelectric β-phase even with relatively low coating content of PVDF-CNF-TEOS. The study demonstrates that the pad-dry-cure method can potentially be used for the development of piezoelectric nanocomposite-coated wearable new textiles for sensors and energy harvesting applications. We believe that our study may inspire the research area for future advanced applications.

Lipoprotein Fractions and Antithrombin III Consumption During Clotting

1982 ◽  
Vol 47 (03) ◽  
pp. 236-238 ◽  
Author(s):  
J H Winter ◽  
B Bennett ◽  
F McTaggart ◽  
A S Douglas
Keyword(s):  
Blood Clotting ◽  
Antithrombin Iii ◽  
Initial Rate ◽  
Density Lipoprotein ◽  
Normal Subjects ◽  
Lipid Levels ◽  
Antithrombin Activity ◽  
Artery Disease ◽  
Immunological Assays ◽  
Total Triglyceride

SummaryPlasma and serum antithrombin levels were measured in functional (initial rate measurement) and immunological assays together with serum lipid levels in normal subjects and patients with coronary artery disease. Specific antithrombin activity in plasma showed a negative correlation with triglyceride levels. The consumption of antithrombin activity during blood clotting was negatively correlated with both serum total triglyceride and heparin precipitable lipoprotein and positively correlated with serum high density lipoprotein cholesterol. Different blood lipoprotein fractions may influence the activity of the antithrombin III molecule.

Platelet Adhesion to Subendothelium - Effect of Shear Rate, Hematocrit and Platelet Count on the Dynamic Equilibrium Between Platelets Adhering to and Detaching from the Surface

1985 ◽  
Vol 54 (04) ◽  
pp. 857-861 ◽  
Author(s):  
Andrea Remuzzi ◽  
Lucia Raffaella Languino ◽  
Vincenzo Costantini ◽  
Vincenzo Guardabasso ◽  
Giovanni de Gartano ◽  
...  
Keyword(s):  
Platelet Adhesion ◽  
Initial Rate ◽  
Dynamic Equilibrium ◽  
Dynamic Condition ◽  
Platelet Reactivity ◽  
Experimental Conditions ◽  
Platelet Suspension ◽  
Shear Rates ◽  
Platelet Concentration ◽  
Adhesion Rate

SummaryThe adherence of human 3H-adenine-labeled platelets to rat subendothelium was quantitated using a rotating probe device. Platelet adhesion increased in relation to the rotation time, reaching a plateau value in about 4-6 min without any further increase. A non-linear fitting analysis of experimental data allowed calculations of initial rate and plateau value of platelet adhesion. Increasing the shear rates (from 35 to 150 sec-1) or the hematocrit (from 10% to 40%), both the adhesion rate and the plateau value were increased. When different platelet concentrations were used the adhesion rate and the plateau calculated increased with platelet concentration. Different plateau values were obtained in the experimental conditions considered. This suggests that the plateau was not reached for the complete occupation of the subendothelial surface by the adherent platelets. Experiments using two different vessels rotated in the same platelet suspension or, viceversa, the same vessel rotated successively in two fresh platelet suspensions, showed that the plateau was not determined by reduced platelet reactivity. Rotating the same vessel first in radiolabeled platelets, until the plateau was reached, and secondly in non labeled platelets, or viceversa, showed that the plateau was indeed a dynamic condition where the number of platelets adhering and detaching reached equilibrium. These observations suggest that the platelet adhesion to subendothelium is the final equilibrium of two platelet fluxes, one adhering to the surface and another detaching from the surface.

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