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Adhesion Between Components of Elastomeric Composite Materials
Published in Nicholas P. Cheremisinoff, Elastomer Technology Handbook, 2020
Polyester has a weakness in that the adhesive strength between polyester and elastomers decreases significantly after being embedded in the elastomer and heated. Iyengar has reported that polyester tended to exhibit hydrolysis of its bonds by amine compounds, such as accelerators or antioxidants compounded into the elastomer.45 For example, Figure 6 shows the decrease of adhesive strength between a polyester and an elastomer when a sulfenamide compound was used as the vulcanization accelerator. Since the elastomer compounds contained moisture, the adhesive strength decreased very markedly. Figure 7 shows the degradation mechanism of polyester by amine compounds. The amine compounds migrate through the adhesive layer and react with the surface layer of the polyester to decrease cord or fabric strength.1,16,78
paniculata (C.B. Clarke) Munir Leaves on Various Gastric Aggressive Factors
Published in Parimelazhagan Thangaraj, Phytomedicine, 2020
P. S. Sreeja, K. Arunachalam, Parimelazhagan Thangaraj
In addition, another class of drugs that was introduced include the proton pump inhibitors (inhibits H+, K+-ATPase pathway in parietal cells) represented by omeprazole, lansoprazole, rabeprazole, pantoprazole, and omeprazole. These drugs were considered as effective in minimizing acid secretion and cellular restitution during the treatment of gastric ulcers (Palileo and Kaunitz 2011). The process for decreasing acid in the gastric environment by these drugs occurs through the acid secretory canaliculi of the parietal cell. By this action, the inactivation of the proton pump occurs via the formation of disulfide bonds between the structure of the drugs and the protein structure of said pump. Its active form, cyclic sulfenamide or sulfenic acid, reacts by covalently binding to the sulfhydryl group of the proton pump extracellular domain cysteine, which enables the inhibition of the hydrochloric acid secretion. However, this type of drug therapy causes side effects, such as lower vitamin B12 and iron absorption, hypergastrinemia, thrombocytopenia, risk of pneumonia, headaches, nausea, weakness, diarrhea, and gastric cancer, as well as a greater susceptibility to bone fractures (Dacha et al. 2015; Singh et al. 2018).
Quantification of Tissue Doses of Carcinogenic Aromatic Amines
Published in Frederick C. Kopfler, Gunther F. Craun, Environmental Epidemiology, 2019
Paul L. Skipper, Matthew S. Bryant, Steven R. Tannenbaum
The cysteine sulfinamide adduct with hemoglobin is not produced by direct reaction of an aromatic hydroxylamine, but requires the intermediate production of the corresponding aromatic nitroso compound. This intermediate is the result of a heme-mediated oxidation in which the heme iron is also oxidized, yielding methemoglobin. The immediate reaction product of the nitroso arene with cysteine is the result of nucleo-philic addition of sulfur at the nitrogen atom. This unstable N-hydroxy sulfenamide rearranges to the more stable sulfinamide. The reaction sequence has been demonstrated in vitro with thioglycerol and nitrosobenzene [11] and it is assumed that the same occurs in vivo in hemoglobin.
Investigate the effect of ground tyre rubber as a reinforcement filler in natural rubber hybrid composites
Published in Soft Materials, 2023
P. Kaliyappan, M. Dhananchezian
In this two-roll mill, the NR was blended with EPDM or CR. The GTR was obtained by grinding at ambient temperature was added at different proportions (0, 10, 20, 30, and 40 phr) with NR/EPDM or NR/CR composites. The duration of this mixing takes place within 6 to 7 minutes. Further, the fillers (silica, Ny 6, and CB) along with the coupling agent (Diethylene Glycol – DEG) were added to the composition after 8 to 10 minutes. At the last stage of sample preparation, the other ingredients used were of commercial grade such as Diphenyl Guanidine (DPG), Light magnesium oxide (LMgO), Stearic Acid (SA), Zinc Oxide (ZnO), 2,2,4-Trimethyl-1,2 Dihydroquinoline (TDQ), and aromatic oil were added, which are regularly used in the rubber industry, and the accelerators (N-Cyclohexyl-2-Benzothiazole Sulfenamide (CBS), Tetra Methyl Thiuram Disulfide (TMTD), Zinc Dibutyl Dithiocarbamate (ZDBC)) and vulcanization (sulfur) were added to the composite from 11 to 15 minutes. Afterward, the hybrid composites were kept at room temperature for 24 hours. Finally, the composites were developed with a dimension of 15 × 15 x 2 by an electrically heated hydraulic press held for 6 minutes at a pressure of 12.41 MPa and a temperature of 165°C.