Optimization of Cutting Parameters in Turning of Titanium Alloy (Grade 5) by Analysing Surface Roughness, Tool Wear and Energy Consumption.

In this study, Ti 6Al-4 V (grade 5) ELI alloy was machined with minimum energy and optimum surface quality and minimum tool wear. The appropriate cutting tool and suitable cutting parameters have been selected. As a result of the turning process, average surface roughness (Ra), tool wear and energy consumption were measured. The results have been analyzed by normality test, linear regression model, Taguchi analysis, ANOVA, Pareto graphics and multiple optimization method. It has been observed that high tool wear value increases Ra and energy consumption. In multiple optimization, it was concluded that it made predictions with 89,1% accuracy for Ra, 58,33% for tool wear, 96,75% for energy consumption. While the feed rate was the effective parameter for Ra and energy consumption, the effective parameter in tool wear was the cutting speed. Our study has revealed that by controlling energy consumption, surface quality can be maintained and tool wear can be controlled.

Effect of melatonin on element distribution in the liver tissue of diabetic rats subjected to forced exercise.

The objective of the present study was to investigate the effects of melatonin supplementation on elements in the liver of diabetic rats subjected to acute swimming exercise. Eighty adult male rats were equally divided into eight groups. Group 1, general control. Group 2, melatonin-supplemented control. Group 3, melatonin-supplemented diabetic control. Group 4, swimming control. Group 5, melatonin-supplemented swimming. Group 6, melatonin-supplemented diabetic swimming. Group 7, diabetic swimming. Group 8, diabetic control. Liver tissue samples were analyzed for lead, cobalt, molybdenum, chrome, sulphur, magnesium, manganese, sodium, potassium, phosphorus, copper, iron, calcium, zinc, selenium. The highest cobalt, chrome values were found in the groups 7, 8 and the groups 5, 6 respectively. Groups 3 and 7 had the highest copper values. Iron and potassium values were higher in the groups 1 and 4. Group 6 had increased magnesium value, and groups 6, 7, 8 were found to have the highest manganese levels. The highest lead values were found in the groups 5 and 6. Group 6 had the highest selenium levels. The highest zinc levels were established in 1 and 2. Groups 1, 2, 5 and 6 were found to have the highest calcium values. The results of our study indicate that melatonin supplementation in diabetes and forced exercise significantly alters the element metabolism in the liver (Tab. 3,Ref. 33).

Protective effect of melatonin on lipid peroxidation in various tissues of diabetic rats subjected to an acute swimming exercise.

BACKGROUND: The present study aimed to explore the effect of melatonin administration on lipid peroxidation in various tissues of rats with streptozocin induced diabetes and subjected to an acute swimming exercise. METHODS: The study used 80 adult male rats, which were equally allocated to 8 groups: Group 1, general control; Group 2, melatonin-administered control; Group 3, melatonin-administered diabetic control; Group 4, swimming control; Group 5, melatonin-administered swimming; Group 6, melatonin-administered diabetic swimming; Group 7, diabetic swimming; Group 8, diabetic control. Diabetic rats were administered 3 mg/kg/day ip melatonin for 4 weeks. At the end of the study, the animals were decapitated to collect samples from liver, lung and spleen tissues, which were then analyzed to determine levels of liver MDA (nmol/gram/protein) and GSH (mg/g/protein). RESULTS: The highest MDA values in liver, lung and spleen tissues were obtained in the Group 7. The values in the Group 8 were lower than those in the Group 7, but higher than in all other groups. The Group 5 and 6 had the highest liver, lung and spleen GSH values. CONCLUSION: Results obtained from the study indicate that the increase in free radical production and the inhibition of antioxidant activity in diabetes and acute exercise are both prevented by melatonin administration (Tab. 2, Ref. 30).

Short duration exhaustive running exercise does not modify lipid hydroperoxide, glutathione peroxidase and catalase.

AIM: Oxidative stress occurs only when exercise is exhaustive and is independent of the absolute duration of exercise. In this study the effects of short duration (03:50 +/- 00:06 min) high-intensity exhaustive exercise on lipid peroxidation and antioxidant status were examined. METHODS: A total of thirty-seven male university students (23.9+/-0.6 years old) participated in this study. None was involved in a regular training program before the study. Intensities of exercises were determined according to the maximum slope and speed they could run in Bruce Test Protocol which is used for determining V.O2max of the participants. Just before and after the high intensity exhaustive running exercise test, venous blood was collected and centrifuged to separate the plasma. RESULTS: Lipid hydroperoxides (LOOH) did not change, glutathione peroxidase (GPx) decreased (2%) and catalase (CAT) increased (13%) at the pre and post exhaustive exercise test. These changes were not statistically significant (P>0.05). On the other hand, lactate dehydrogenase (LDH) levels significantly increased (31%) (P< 0.001). CONCLUSION: As a result, it may be claimed that short duration exhaustive exercise test produced no important changes in LOOH, GPx and CAT levels. And exhaustive exercise-induced oxidative stress may be related with exercise duration.

Lipase and esterase-catalyzed acylation of hetero-substituted nitrogen nucleophiles in water and organic solvents.

The lipase- and esterase-catalyzed acylations of hydroxylamine and hydrazine derivatives with octanoic acid and ethyl octanoate are described. The influence of solvent and nucleophile on the initial reaction rate was investigated for a number of free and immobilized enzymes. Initial rates were highest in water, but the overall productivity was optimal in dioxane. Octanoic acid (250 g/L) was converted for 93% into the hydroxamic acid in 36 h with only 1% (w/w) Candida antarctica lipase B (Novozym 435) in dioxane at 40 degrees C. This translates to a catalyst productivity of 68.5 g. g(-1). day(-1) and a space time yield of 149 g. L(-1). day(-1), unprecedented figures in the direct reaction of an acid with a nitrogen nucleophile in an organic solvent.