Toxic and sublethal effects of endosulfan and carbaryl on growth and egg production of Moina micrura Kurz (Cladocera: Moinidae)

The toxic and sublethal effects of endosulfan and carbaryl on a cladoceran, Moina micrura, were studied. The dosage-mortality regression lines gave LC(50) values for the pesticides. The cumulative growth and egg production during life were inhibited to 31.8 and 20.7% in endosulfan, and 28.2 and 13.7% in carbaryl-treated animals, respectively. The growth coefficient (K value) and the intrinsic rate of natural increase per day (r value) of control M. micrura were 0.144 and 0.377, respectively; these decreased to 0.121 and 0.346 in carbaryl-, and 0.073 and 0.356 in endosulfan-treated animals, respectively.     

Studies on removal of metal ions and sulphate reduction using rice husk and Desulfotomaculum nigrificans with reference to remediation of acid mine drainage

The utility of rice husk as an adsorbent for metal ions such as iron, zinc and copper from acid mine water was assessed. The adsorption isotherms exhibited Langmuirian behavior and were endothermic in nature. The free energy values for adsorption of the chosen metal ions onto rice husk were found to be highly negative attesting to favorable interaction. Over 99% Fe(3+), 98% of Fe(2+) and Zn(2+) and 95% Cu(2+) uptake was achieved from acid mine water, with a concomitant increase in the pH value by two units using rice husk. The remediation studies carried out on acid mine water and simulated acid mine water pretreated with rice husk indicated successful growth of Desulfotomaculum nigrificans (D. nigrificans). The amount of sulphate bioreduction in acid mine water at an initial pH of 5.3 was enhanced by D. nigrificans from 21% to 40% in the presence of rice husk filtrate supplemented with carbon and nitrogen. In simulated acid mine water with fortified husk filtrate, the sulphate reduction was even more extensive, with an enhancement to 73%. Concurrently, almost 90% Fe(2+), 89% Zn(2+) and 75% Cu(2+) bioremoval was attained from simulated acid mine water. Metal adsorption by rice husk was confirmed in desorption experiments in which almost complete removal of metal ions from the rice husk was achieved after two elutions using 1M HCl. The possible mechanisms of metal ion adsorption onto rice husk and sulphate reduction using D. nigrificans are discussed.     

Studies on enzymes associated with calcification of the cuticle of the hermit crab Clibanarius olivaceous

In the anomuran Clibanarius olivaceous Henderson, the cuticle of the cephalic and thoracic regions is calcified, while that of the abdominal region is uncalcified. Histochemical observations have been made on the possible enzymes involved in the process of calcification of cuticle. The calcified regions show the presence of enzymes such as phosphorylase, alkaline phosphatase and carbonic anhydrase. The possible role of phosphorylase in calcification may be production of phosphoric esters, which form the required substrate for alkaline phosphatase. The latter appear to be associated with the production of phosphate ions from phosphoric esters. The carbonic anhydrase may be associated with the production of carbonate ions. The suggestion that these enzymes are involved in the process of calcification is further supported by experimental evidence of inhibition of the action of enzymes by enzyme inhibitors. The inhibition of enzymes leads to reduction in the amount of calcium added to the cuticle.This paper formed part of a thesis approved for the award of Ph. D. degree of the University of Madras.     

Effective application of ethanol in diesel engines

This work aimed to prove the effects of adding different proportions of ethanol with diesel (DE) and ethanol–water mixture with diesel (DEW) in a single-cylinder diesel engine on the performance, emissions, and combustion parameters. The blends were stabilized by tetra methyl ammonium bromide (TMAB) as the additive. The study was conducted at two operating conditions initially on a normal diesel engine and in the second case the engine piston, valves, and cylinder head coated with zirconia (ZrO₂) alumina (Al₂O₃). The results showed that the addition of 10% ethanol with diesel performed almost equivalent to neat diesel with 29.2% BTE and a 17.7% decrease in smoke and an 11.4% increase in NOx emission at peak load compared to that of the base fuel. Modified engines with thermal barrier coating (TBC) performed superior to normal engines with 4% and 5.5% increase in BTE, respectively, for DE- and DEW-type fuels with reduced exhaust emissions. A 5% addition of water with diesel–ethanol blends favors a higher proportion of ethanol to be employed in diesel engines.     

Effect of ultrasonic pretreatment on secondary sludge and anaerobic biomass to enhance biogas production

Journal of Material Cycles and Waste Management - Anaerobic digestion studies were carried out with tannery excess secondary sludge obtained from common effluent treatment plant. The excess sludge...     

Nature and composition of the cephalic and thoracic cuticles of the hermit crab Clibanarius olivaceous

The structure and composition of the cephalic and thoracic cuticles of Clibanarius olivaceous Henderson are described. The cephalic cuticle is completely hardened due to tanning of the epicuticle and the outer part of the procuticle (pigmented Layer). The thoracic cuticle is partially hardened. The differences in extent of tanning reflect the chemical composition of the respective regions. The epicuticle of the cephalic region contains a protein rich in tyrosine, which combines with a sterol to form a lipoprotein complex. This in turn forms the precursor to sclerotin. Phenolic substances appear to be oxidized to quinones by the action of phenolase. The outer part of the procuticle of the cephalic region also contains phenolic substances, but this layer remains only partially tanned. This partial hardening is due to the presence of an inhibitory substance having the nature of ascorbic acid. In the epicuticle of the thoracic region, however, an arrest in tanning appears to be due not to the presence of an inhibitory substance, but to the absence of phenolase necessary for the oxidation of tanning material. In C. olivaceous, the tanning process is much abbreviated. The primary cause of hardening is calcification. The sulphydryl groups and acid mucopolysaccharide detected in the cephalic and thoracic cuticles of C. olivaceous are involved in calcification. It is suggested that hardening of the cephalic and thoracic cuticles in C. olivaceous constitutes a protection during those periods when these parts are exposed to the environment.     

Performance studies of low GWP refrigerants as environmental alternatives for R134a in low-temperature applications

Environmental Science and Pollution Research - Climate change is an important environmental issue that is causing global temperatures to rise. The primary environmental targets are to reduce carbon...     

Larvicidal and repellent activity of N-methyl-1-adamantylamine and oleic acid a major derivative of bael tree ethanol leaf extracts against dengue mosquito vector and their biosafety on natural predator

Environmental Science and Pollution Research - Aegle marmelos (L.) Correa belongs to the family Rutaceae is generally known as “bael fruit tree” occuring across the south Asian...