نتایج جستجو برای: crystallization
تعداد نتایج: 23168 فیلتر نتایج به سال:
Viscosity has been determined during isothermal crystallization of an andesite from Tungurahua volcano (Ecuador). Viscosity was continuously recorded using the concentric cylinder method and employing a Pt-sheathed alumina spindle at 1 bar and from 1400°C to subliquidus temperatures to track rheological changes during crystallization. The disposable spindle was not extracted from the sample but...
Crystallization-driven self-assembly of polyethylene-b-poly(tert-butylacrylate) (PE-b-PtBA) block copolymers (BCPs) in N,N-dimethyl formamide (DMF) was studied. It is found that all three PE-b-PtBA BCPs used in this work can self-assemble into one-dimensional crystalline cylindrical micelles. When the BCP solution is cooled to crystallization temperature (Tc) from 130 °C, the seed micelles may ...
Protein crystals usually grow at a preferable temperature which is however not known for a new protein. This paper reports a new approach for determination of favorable crystallization temperature, which can be adopted to facilitate the crystallization screening process. By taking advantage of the correlation between the temperature dependence of the second virial coefficient (B(22)) and the so...
Controlled self-organization of nanoparticles can lead to new materials. The colloidal crystallization of non-spherical nanocrystals is a reaction channel in many crystallization reactions. With additives, self-organization can be stopped at an intermediary step-a mesocrystal-in which the primary units can still be identified. Mesocrystals were observed for various systems as kinetically metast...
Spherical crystallization is a novel particle engineering/design technique developed by Kawashima et al, to overcome the problems associated with direct compression. Basically, it's single step process used for size enlargement of single, two or more, small dose or large dose drugs, in combination with or without diluent. The process of spherical crystallization involves simultaneous crystalliz...
Recently we showed how crystallization in microemulsions could lead directly to the most stable polymorph, thereby leapfrogging Ostwald’s rule of stages. Here we consider in more details the crystallization of mefenamic acid from dimethylformamide microemulsions. Crystallization of mefenamic acid from bulk DMF has previously been shown to produce only the metastable Form II irrespective of the ...
effluent from ro (reverse osmosis) systems during recovery gradually becomes concentrated and supersaturated with soluble salts such as calcium carbonate (caco3), calcium sulfate (caso4), barium sulfate (baso4) and silica (sio2). thus we were looking for procedures to prevent precipitation of soluble salts on the membrane surface and decrease membrane permeability. therefore, recovery could be ...
in this investigation we synthesized nax-nanozeolite by hydrothermal crystallization conditions.these nanoparticles were prepared at different conditions in a temperature controlled shaker. thesynthesized zeolites were characterized by instrumental analysis methods, such as x-raydiffraction (xrd), x-ray fluorescence (xrf), scanning electron microscopy (sem) andtransmission electron microscopy (...
We examine the crystallization dynamics of nanoparticles reversibly tethered by DNA hybridization. We show that the crystallization happens readily only in a narrow temperature ‘‘slot’’, and always proceeds via a two-step process, mediated by a highly-connected amorphous intermediate. For lower temperature quenches, the dynamics of unzipping strands in the amorphous state is sufficiently slow t...
Protein crystallization is a major bottleneck in determining tertiary protein structures from genomic sequence data. This paper describes a microfluidic system for screening hundreds of protein crystallization conditions using less than 4 nL of protein solution for each crystallization droplet. The droplets are formed by mixing protein, precipitant, and additive stock solutions in variable rati...
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