Bubble columns are gas- liquid contactors that are widely used in chemical and bio- chemical industries. High mixing that result in high heat and mass transfer rates are amongst their advantages. Heat transfer in a bubble column having a bundle of heaters investigated and the variation of heat transfer coefficient with variation in heaters pitch to diameter ratios in a bundle of heaters reporte...

Abstract: During solidification and casting in metallic molds, the heat flow is controlled by the thermal resistance at the casting-mold interface. Thus heat transfer coefficient at the metal- mold interface has a predominant effect on the rate of heat transfer. In some processes such as low pressure and die-casting, the effect of pressure on molten metal will affect the rate of heat transfer a...

background: soil pollution and accumulation of heavy metals in crops in industrial areas is one of the most important environmental issues threatening the life of plants, animals, and humans. the aim of this study was to determine the concentration of cr and cd in the soil and barberry plants in farms surrounding the qayen cement company, south khorasan province, iran. materials and methods: in...

background: in spite of the great progress in assisted reproductive techniques ( art) and although good quality embryos are transferred pregnancy rates have remained around 30%-35% due to low implantation rates. objective: the aim of this study was to assess and compare the effects of administrating indomethacin or hyoscine suppositories prior to embryo transfer on the pregnancy rate in art cyc...

background: transfer and utilization of research evidence in health promotion have caught great attention in recent years. the objective of this study was to assess the factors affecting knowledge , attitude, and practice (kap) of researchers in golestan university of medical sciences (golestan, iran) regarding research knowledge transfer (kt) in 2010. methods and materials: in this cross-secti...

during spring, summer and winter seasons, sistani donor cows, with normal reproductive status, were superovulated and embryos were recovered non-surgically on day 7. grade a blastocyst embryos were either transferred fresh (spring) or frozen (summer and winter). recovered embryos during summer and winter were exposed to glycerol and frozen using conventional method. during spring season, recipi...

human mitochondrial dna (mtdna) is 16,569 base pairs (bp) in length, coding for 37 genes. during the course of evolution, nearly all the genes expressing ribosomal proteins and ribosomal rnas (rrna) genes have been transferred from the mitochondria to the nucleus. however, mitochondrial dna contains two ribosomal rnas genes (12s and 16s), which have not yet transferred to the nucleus. these two...

heat transfer mechanisms and the solidification process are simulated for a continuous casting machine and the geometric shape of the liquid pool is predicted considering different conditions. a heat transfer and solidification model is described for the continuous casting of steel slabs. the model has been established on the basis of the technical conditions of the slab caster in the continuou...

The mass transfer performance of a pulsed disc and doughnut column for extraction of samarium and gadolinium from aqueous nitrate solution with D2EHPA was investigated. The effects of operating parameters such as pulsation intensity, continuous and dispersed phase velocities on column performance were investigated. The axial dispersion model was used to obtain the overall mass transfer coef...