Double minutes (dm) have been isolated from human tumor cells by zonal centrifugation and by differential pelleting of chromosome suspsension. These methods allowed collection of dm in sufficient quantity and purity for visualization with electron microscopy. Ultrastructurally, the chromatin fibers in dm resemble thrance fragments was found. When the two isolation protocols were compared, diffe...

Switchgrass was pelleted to evaluate the effect of densification on acidic and alkaline pretreatment efficacy. Bulk density and durability of pellets were 724 kg/m(3) and 95%, respectively. Ground switchgrass (D(90) = 21.7 mm) was further ground to a fine power (D(90) = 0.5mm) in the pellet mill prior to densification. This grinding increased enzymatic hydrolyzate glucose yields of non-pretreat...

Both the U.S. and world economies have been depending on petroleum based liquid transportation fuels (such as gasoline, diesel, and jet fuels), which are finite and nonrenewable energy sources. Increasing demands and concerns for the reliable supply of liquid transportation fuels make it important to find alternative sources to petroleum based fuels. One such alternative is cellulosic ethanol. ...

in order to determination of optimum quantity of seed pelleting materials due to sugar beet monogerm seed size. this study was carried out in seed technology department during 1997-1998. monogerm cultiver 9597 seed lot (300kg) was firstly graded by 7 round sieves and then 7 rectangle sieves graded each bound. some factors such as germination , monogermity and proportionate seed pelleting materi...

Centrifugal separations can be classified into three categories, namely differential pelleting, rate-zonal centrifugation and isopycnic centrifugation. Although differential pelleting is the most widely used technique, it has only a limited potential for providing the investigator with purified material. Thus only the last two techniques, both of which involve separations on density gradients, ...

Feed ingredients and complete feeds are exposed to varying degrees of heating during manufacturing and processing. Heat treatment of soybeans is necessary to de-nature endogenous trypsin inhibitors and maximize nutritional value, but overheating can damage protein and reduce nutritional value. This study was conducted to determine the effects of extrusion cooking, the primary method of aquafeed...

A mathematical model was developed to simulate fluid flow, heat transfer, and melting kinetics of starch in a co-rotating intermeshing twin-screw extruder (TSE). The partial differential equations governing the transport phenomena of the biomaterial in the extruder were solved by a finite element scheme. For validating the model, the predicted product pressure, bulk temperature at the entrance ...

In this paper, a delay-compensated bang-bang control design methodology for the control of the nozzle output flow rate of screw extruder-based three-dimensional printing processes is developed. A geometrical decomposition of the screw extruder in a partially and a fully filled regions allows to describe the material convection in the extruder chamber by a one-dimensional hyperbolic partial diff...