Effects of dispersant (Tri polyphosphate sodium) amount on gel viscosity, mechanical activation of raw materials, raw materials mixture composition, and reduction atmosphere on the prepared composites and NiO reduction mechanism were investigated. It was found that 2.5 wt % dispersant is an optimum amount for a gel suspension with 50 V% of solid consisting of alumina, graphite, and nickel oxide. XRD results of reduced and sintered product (at 1200-1500 °C) showed that alumina, nickel, and nickel aluminate spinel are present in the prepared composite. The porosity of the composite made with 12 h ball milledalumina was 48%, while it was 64 % in the sample made with 20 min ball-milled alumina. The results of TG-DTA analyses showed that the reduction temperature and mechanism are dependent on the raw materials' ball milling time. Thermal analyses revealed that mechanical activation of raw materials decreases the NiO reduction temperature and increases the metallic Ni production.
Saline environments are largely unexplored sources for actinomycetes with the potential to produce biologically active secondary metabolites. A total of 34 actinomycete strains from water, sediments and mostly rhizosphere (82%) were collected from different sites of Howz Soltan Lake in Iran. Based on phylogenetic analysis, the isolated strains belonged to the genera Streptomyces, Nocardia and Saccharomonospora. Among the isolated actinomycetes, several strains had valuable biotechnological applications such as growth inhibition of human tumor cells. The results of cytotoxic assay revealed strain act9 having the most potent extract (19.716 ± 5.72 µg/ml) against the MDA-MB-231 human breast cancer cell. Also 38% of the strains had an antimicrobial activity against some pathogenic and nonpathogenic microorganisms. The ethyl-acetate extract of act18 showed the most antibacterial effect against Staphylococcus aureus, MRSA, and was further analyzed by GC/MS. Ar-tumerone (26.41%) and Butyl isodecyl phthalate (21.77%) were the main constituents detected in the extract.. This is the first time this compound is being detected in a prokaryote. Act18 showed the most 16s rRNA sequence similarity to Streptomyces youssoufiensis. In addition, a number of the isolates produced different enzymes including lipase, amylase, protease, gelatinase, urease and lecetinase. Also, the plant growth promoting activity of some actinomycete strains were shown. Some of the strains belonging to the genera Streptomyces and Nocardia increased the seed germination, stem length and the number of Echium leaves during the 20 days. Consequently, it was concluded that actinomycetes isolated from these saline lake habitats are potentially valuable for biotechnological applications.
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