Preparation of briquettes from the Golden Horn bottom sediments by hydro-thermal agglomeration process.

The Golden Horn (GH) sediments, which consist mainly of clay, organic substances and heavy metals, are formed with the contribution of industrial and domestic wastes released in the Golden Horn Estuary. On account of their mineralogical and chemical composition, these sediments may be regarded as a suitable raw material for briquette production. In this study, the utilization of GH dredged bottom sediments was investigated for preparation of briquettes. Dried GH sediments were mixed with lime and sand in different percentages, moulded at various squeezing pressures and hardened under several steam pressure values by autoclaving. The briquettes produced through these different process conditions were tested for compressive strength according to the Turkish standards (TS705). It was found that variations in compressive strength were dependent on the amount of lime (Ca(OH)2) and sand (SiO2) added. Results show that the compressive strength increased with increasing lime and decreasing sand in the mixtures prepared for briquettes. It is concluded that briquettes with a compressive strength value of 294 kgf cm(-2) can be produced. This allows the GH sediments to be taken into account as a raw material in brick production, as far as compressive strength requirements are concerned. This possibility may represent an important way either for reducing environmental pollution or for recycling waste materials in industrial applications.     

Evaluation of the inhibitory effect of abamectin on mammalian butyrylcholinesterase: Enzyme kinetic and molecular docking studies

ABSTRACT

Abamectin, a blend of the natural avermectins B_1a and B_1b, is a widely-used insecticide/miticide with relatively low toxicity to mammals. Exposure to high doses of it, however, leads to cholinergic-like neurotoxic effects. Butyrylcholinesterase, which is best known for its abundant presence in plasma, is a serine hydrolase loosely coupled with the cholinergic system. It protects and supports the neurotransmitter function of its sister enzyme acetylcholinesterase. Here, using experimental and computational studies, we provide evidence demonstrating that abamectin is a potent (IC₅₀ = 10.6 μM; K_i = 2.26 ± 0.35 μM) inhibitor of horse serum butyrylcholinesterase and that it interacts with the enzyme in a reversible, competitive manner predictively to block the mouth of the active-site gorge of the enzyme and to bind to several critical residues that normally bind/hydrolyze choline esters.     

Effect of 2,4-dichlorophenoxyacetic acid on growth, protein and chlorophyll-a content of Chlorella vulgaris and Spirulina platensis cells

In this study, effect of different 2,4 -dichlorophenoxyacetic acid (2,4-D) concentrations (0.0, 9.10(-5), 9.10(-4), 9.10(-3) and 9.10(-2) mM) on growth rate, content of protein and chlorophyll-a in Chlorella vulgaris and Spirulina platensis cells was investigated. The most stimulatory effect on growth rate, protein and pigment ratio of C. vulgaris and S. platensis was observed at 9.10(-4) mM concentrations of 2,4-D. The results show that low concentrations of 2,4-D have hormonal effect due to being a synthetic auxin. Cell number protein and pigment rates were inhibited at 9.10(-2) mM concentration in C. vulgaris. Such parameters were inhibited in S. platensis, both at 9.10(-3) and 9.10(-2) mM 2,4-D concentrations. This is due to herbicidal effect of high concentrations of 2,4-D. S. platensis was found to be more sensitive than S. vulgaris to 2,4-D applications. The use of algae as bio-indicators in herbicide contaminated fresh water habitats, was discussed.