An investigation on cavitation-corrosion behavior of Ni/ß-SiC nanocomposite coatings under ultrasonic field.

Ni/ß-SiC nanocomposite coating was electroplated on the 17-4 PH SS (precipitation-hardening stainless steel) in modified Watt's bath. The role of cyclic-cavitation (Duty cycle: 50%) on corrosion behavior of Ni/ß-SiC nanocomposite coating in 3.5 wt% NaCl solution was investigated using open circuit potential (OCP), potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) measurements. The results of OCP tests demonstrated that cavitation led to positive shifts in the potential for Ni composite coating, while it caused the potential negative shifts in the case of 17-4 PH SS. The results of the polarization tests under cavitation condition exhibited positive shifts in potential and an increase in current density up to a specific anodic potential. In higher anodic potentials, the cavitation had a reverse effect on potential and current density. Moreover, it increased the overall corrosion current density. EIS measurements illustrated a severe reduction in electrochemical resistance of both 17-4 PH SS (from 228.15 kΩ.cm2 to 14.85 kΩ.cm2) and Ni composite coating (from 20.19 kΩ.cm2 to 5.00 kΩ.cm2) after 20 h of the cavitation tests. The cumulative mass loss measurements showed that the mass loss for the substrate (10.3 mg.cm-2) was about five times more than that of Ni composite coating (2.3 mg.cm-2). Also, in the coated specimen, the incubation time is increased and the growth slop of the accelerating period decreased under cavitation condition.

Resveratrol addition to in vitro maturation and in vitro culture media enhances developmental competence of sheep embryos.

The present study aimed to examine the effects of adding different concentrations of resveratrol during in vitro culture (IVC) alone and during both in vitro maturation (IVM) and IVC on ovine blastocyst yield and quality. Therefore, this study was conducted in two separate experiments. The first experiment was carried out to test the effect of different concentrations of resveratrol (0, 0.1, 0.25, 0.5, 2.0, and 5.0 µM) in the IVC medium on cleavage, morula, developmental potential of blastocyst, and total cell number (TCN) of the embryos. Addition of 0.25 and 0.5 µM of resveratrol during IVC significantly enhanced morula and blastocyst rates as compared with other groups (P < 0.05). Also, supplementation of the IVC medium with 0.5 µM of resveratrol had beneficial effects on trophectoderm cells (TE), inner cell mass (ICM), and TCN of blastocysts. In the second experiment, the same concentrations of resveratrol (0, 0.1, 0.25, 0.5, 2.0, and 5.0 µM) were applied during IVM and IVC. Therefore, oocytes were matured in vitro in the presence of different concentrations of resveratrol for 22-24 h. After in vitro fertilization, presumptive zygotes were cultured in media containing 0, 0.1, 0.25, 0.5, 2.0, and 5.0 µM of resveratrol for 8 d. No significant difference was found in the percentage of oocytes developed to MII (0, 0.1, 0.25, 0.5, and 2.0 µM of resveratrol), but the percentage of oocytes developed to MII were significantly lower in 5.0 µM of resveratrol in comparison with other groups. Addition of 0.5 µM of resveratrol to the maturation and culture media significantly increased morula and blastocyst rates compared with other groups (P < 0.05). However, a too high concentration of resveratrol (5.0 µM) during IVM and IVC decreased cleavage, morula, and blastocyst rates compared with low concentrations (P < 0.05). Treatment with 0.5/0.5 µM of resveratrol during IVM/IVC significantly improved the TE, ICM, and TCN of blastocysts. In conclusion, sequential treatment with 0.5 µM of resveratrol during IVM and IVC and during IVC alone improved the developmental competence of oocytes, which was reflected in higher blastocyst rates and TCN of blastocysts.

Effects of caerulein and CCK antagonists on tolerance induced to morphine antinociception in mice.

Different groups of mice received one daily dose (50 mg/kg) of morphine subcutaneously (SC) for 3, 4 or 5 days to develop tolerance to the opioid. The antinociceptive response of morphine (9 mg/kg) was tested in the hot-plate test 24 h after the last dose of the drug. Tolerance to morphine was obtained in all groups. The group of mice that received morphine for 4 days was employed for the rest of the experiments. Pretreatment of animals with a single dose of caerulein (0.025, 0.05, and 0.1 mg/kg, SC) 30 min prior to receiving morphine (50 mg/kg; during the development of tolerance to the opioid) on day 1, 2, 3, 4 or 5 of morphine administration potentiate antinociception induced by morphine (test dose of 9 mg/kg). The dose of 0.05 mg/kg of caerulein, used 30 min before morphine administration on day 3, was also used to evaluate the effects of antagonists on caerulein-induced decrease in tolerance. The selective cholecystokinin (CCK) receptor antagonists, MK-329 [1-methyl-3-(2 indoloyl)amino-5-phenyl-3H-1,4-benzodiazepin-2-one; 0.25 and 0.5 mg/kg] or L-365,260 [3R(+)-N-(2,3-dihydro-1-methyl-2-oxo-5-phenyl-1H- 1,4-benzodiazepin-3-yl)-N-(3-methyl-phenyl)urea: 0.25 and 0.5 mg/kg] decreased potentiation of morphine response induced by caerulein. MK-329 or L-365,260, when were injected 35 min before morphine injection during the development of tolerance and on day 3, decreased the tolerance to morphine. A single administration of MK-329 or L-365,260 (in the absence of caerulein) 35 min and 48 h before the test dose of morphine (9 mg/kg) potentiated the antinociception of morphine in nontolerant animals. In conclusion, CCK mechanism(s) may interact with morphine tolerance.