Plasticization of Rubber in the Form of Latex

1954 ◽  
Vol 27 (1) ◽  
pp. 271-276 ◽  
Author(s):  
Marc Conté
Keyword(s):  
Hydrogen Peroxide ◽  
Chemical Reactions ◽  
Room Temperature ◽  
Ph Value ◽  
Inhibitory Effect ◽  
Rubber Latex ◽  
Adhesive Properties ◽  
Harmful Effects ◽  
Latex Rubber

Abstract When in the form of latex, rubber can be oxidized by thiols under hot conditions. The reaction apparently proceeds by the same mechanism as that characteristic in the action of peptizing agents on rubber during mastication. The results obtained confirm the hypothesis that the thiol is transformed quantitatively into the corresponding disulfide, with resultant oxidation of the rubbert. This transformation is a function of the pH value, and the best results are obtained when the pH value is around 4 and in the absence of NH4 ions (which have an inhibitory effect). Latex preparations of this type can be utilized for studying the chemical reactions of rubber in emulsion and for the preparation of rubber derivatives which are more soluble than those prepared from rubber latex which has not been degraded. In addition, such latex preparations are excellent adhesives which, in contrast to already known products (latex treated with hydrogen peroxide or other peroxides), give a sticky film by simple drying at room temperature. In this way heating can be avoided in cases where it has harmful effects and where the use of an oven is inconvenient. Finally, this type of latex is more adaptable to certain direct applications, both because of the superior adhesive properties of the rubber and because, with a relatively plastic coagulum, mastication is easier.

Comparative Labelling and Biokinetic Studies of 99mTc-EDTA(Sn) and 99mTc-DTPA(Sn)

1977 ◽  
Vol 16 (01) ◽  
pp. 30-35 ◽  
Author(s):  
N. Agha ◽  
R. B. R. Persson
Keyword(s):  
Complex Formation ◽  
Significant Influence ◽  
Room Temperature ◽  
Ph Value ◽  
Maximum Activity ◽  
Reduction Step ◽  
Labelling Yield ◽  
Different Temperatures ◽  
Kinetics Of

SummaryGelchromatography column scanning has been used to study the fractions of 99mTc-pertechnetate, 99mTcchelate and reduced hydrolyzed 99mTc in preparations of 99mTc-EDTA(Sn) and 99mTc-DTPA(Sn). The labelling yield of 99mTc-EDTA(Sn) chelate was as high as 90—95% when 100 μmol EDTA · H4 and 0.5 (Amol SnCl2 was incubated with 10 ml 99mTceluate for 30—60 min at room temperature. The study of the influence of the pH-value on the fraction of 99mTc-EDTA shows that pH 2.8—2.9 gave the best labelling yield. In a comparative study of the labelling kinetics of 99mTc-EDTA(Sn) and 99mTc- DTPA(Sn) at different temperatures (7, 22 and 37°C), no significant influence on the reduction step was found. The rate constant for complex formation, however, increased more rapidly with increased temperature for 99mTc-DTPA(Sn). At room temperature only a few minutes was required to achieve a high labelling yield with 99mTc-DTPA(Sn) whereas about 60 min was required for 99mTc-EDTA(Sn). Comparative biokinetic studies in rabbits showed that the maximum activity in kidneys is achieved after 12 min with 99mTc-EDTA(Sn) but already after 6 min with 99mTc-DTPA(Sn). The long-term disappearance of 99mTc-DTPA(Sn) from the kidneys is about five times faster than that for 99mTc-EDTA(Sn).

Oxidation of hydrogen peroxide at the dropping mercury electrode

1984 ◽  
Vol 49 (10) ◽  
pp. 2320-2331 ◽  
Author(s):  
Miroslav Březina ◽  
Martin Wedell
Keyword(s):  
Hydrogen Peroxide ◽  
Superoxide Anion ◽  
Ph Value ◽  
Mercury Electrode ◽  
Electrode Process ◽  
Electrochemical Processes ◽  
Dropping Mercury Electrode ◽  
Oxidation Of Hydrogen ◽  
Decreasing Ph ◽  
Rate Controlling Step

Reduction of oxygen and oxidation of hydrogen peroxide at the dropping mercury electrode are electrochemical processes strongly influenced both by the pH value and the anions in solution. With decreasing pH, both processes become irreversible, especially in the presence of anions with a negative φ2 potential of the diffusion part of the double layer. In the case of irreversible oxygen reduction, the concept that the rate-controlling step of the electrode process is the acceptance of the first electron with the formation of the superoxide anion, O2-, was substantiated. Oxidation of hydrogen peroxide becomes irreversible at a lower pH value than the reduction of oxygen. The slowest, i.e. rate-controlling step of the electrode process in borate buffers at pH 9-10 is the transfer of the second electron, i.e. oxidation of superoxide to oxygen.

scholarly journals Hormetic Concentrations of Hydrogen Peroxide but Not Ethanol Induce Cross-Adaptation to Different Stresses in Budding Yeast

2014 ◽  
Vol 2014 ◽  
pp. 1-5 ◽  
Author(s):  
Halyna M. Semchyshyn
Keyword(s):  
Hydrogen Peroxide ◽  
Dose Response ◽  
Budding Yeast ◽  
Regulatory Protein ◽  
Colony Growth ◽  
Inhibitory Effect ◽  
Cross Resistance ◽  
Mild Stress ◽  
Low Concentrations ◽  
Cross Adaptation

The biphasic-dose response of microorganisms to hydrogen peroxide is a phenomenon of particular interest in hormesis research. In different animal models, the dose-response curve for ethanol is also nonlinear showing an inhibitory effect at high doses but a stimulatory effect at low doses. In this study, we observed the hormetic-dose response to ethanol in budding yeastS. cerevisiae. Cross-protection is a phenomenon in which exposure to mild stress results in the acquisition of cellular resistance to lethal stress induced by different factors. Since both hydrogen peroxide and ethanol at low concentrations were found to stimulate yeast colony growth, we evaluated the role of one substance in cell cross-adaptation to the other substance as well as some weak organic acid preservatives. This study demonstrates that, unlike ethanol, hydrogen peroxide at hormetic concentrations causes cross-resistance ofS. cerevisiaeto different stresses. The regulatory protein Yap1 plays an important role in the hormetic effects by low concentrations of either hydrogen peroxide or ethanol, and it is involved in the yeast cross-adaptation by low sublethal doses of hydrogen peroxide.

scholarly journals A Mn(iii) polyoxotungstate in the oxidation of organosulfur compounds by H2O2 at room temperature: an environmentally safe catalytic approach

2016 ◽  
Vol 6 (9) ◽  
pp. 3271-3278 ◽  
Author(s):  
Tiago A. G. Duarte ◽  
Sónia M. G. Pires ◽  
Isabel C. M. S. Santos ◽  
Mário M. Q. Simões ◽  
M. Graça P. M. S. Neves ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Room Temperature ◽  
Organosulfur Compounds ◽  
Keggin Type ◽  
Environmentally Safe

A manganese monosubstituted Keggin-type polyoxometalate was used as a catalyst in the oxidation of recalcitrant organosulfur compounds by hydrogen peroxide at room temperature.

Inhibitory effect of FSLLRY-NH2 on inflammatory responses induced by hydrogen peroxide in HepG2 cells

2017 ◽  
Vol 40 (7) ◽  
pp. 854-863 ◽  
Author(s):  
Yeon Joo Lee ◽  
Su Jin Kim ◽  
Kyoung Wan Kwon ◽  
Won Mo Lee ◽  
Wi Joon Im ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Hepg2 Cells ◽  
Inflammatory Responses ◽  
Inhibitory Effect

Zinc carbonate recovery from brass melting slag

2021 ◽  
Vol 98 ◽  
pp. 14-18
Author(s):  
Thao Nguyen Thi ◽  
◽  
Nam Pham Ky ◽  
Ngoc Tran Vu Diem
Keyword(s):  
Sulfuric Acid ◽  
High Purity ◽  
Room Temperature ◽  
Ph Value ◽  
Zinc Carbonate ◽  
Leaching Solution ◽  
Optimized Conditions ◽  
Melting Slag

Brass melting slag (20.38 wt.% Zn) was leached in sulfuric acid with concentration of (50 + 80) g/l H2SO4, leaching temperature of (30 + 60) °C for (30 + 120) min. The optimized conditions for 94.16% Zn extraction from brass melting slag were found as 70 g/l H2SO4, room temperature and 90 min. The leaching solution was purified by removal of Fe through Fe(OH)3 precipitation when adding ZnO to adjust pH value of 5. The solution was continuously cemented by Zn metal at 60 °C for 60 min to obtain Cu metal with high purity of 99 wt.% Cu. The purified solution with 37.64 g/l Zn was modified by Na2C03 to have pH value of about 6 and precipitation of ZnC03 (94.14 %).

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