81. Preparation of enantiomers using high pressure technologiesPaul Thorey, 2010, dissertation Abstract: The study of two different methods of obtaining chiral alcohols is proposed herein.
The requirement of the relatively new paradigm of green chemistry associated with clean
technologies such as biocatalysis or non-conventional solvents, dense gases, was
focused at. Indeed, the two methods of production of chiral alcohols were:
- the conversion of acetophenone into (R)-1-phenylethanol in dense gases
catalysed by Lactobacillus brevis alcohol dehydrogenase and its
coenzyme, NADP/H;
- the resolution of (±)-trans-1,2-cyclohexanediol by cocrystal formation with
tartaric acid followed by supercritical extraction.
In both cases high enantiopurities were achieved (ee>99%).
Keywords: High-pressure technologies, enantiomers, green chemistry, R-1-phenylethanol, Lactobacillus brevis, alcohol dehydrogenase, NADP, liquid propane, enzyme deactivation, resolution, trans-1, 2-cyclohexanediol, tartaric acid, cocrystal, supercritical carbon dioxide, extraction, X-ray diffraction, differential scanning calorimetry
Published in DKUM: 02.02.2011; Views: 3053; Downloads: 146
 Full text (6,25 MB) |
82. The development of a new process for gentle drying, micronisation and formulation of a high viscous biopoymerChristian Reibe, 2011, dissertation Abstract: Biopolymers are characterised by their biodegradable behaviour in certain environments. Especially the development of natural biopolymers from renewable resources is gathering increasing interest in the scientific as well as in the industrial sectors . Since Biopolymers may be tailored to specific requirements, the encapsulation of pharmaceutical compounds or flavours in biopolymers would open wide avenues for the production of controlled- release systems. Most common mechanical pulverisation processes are milling and grinding. With these processes it is not possible to produce specific morphologies like foams or hollow spheres, but always splintered edges. Encapsulation is carried out by common precipitation techniques.
Gelatine, as a widely applied biopolymer, represents one example of those substances of large interest, but it is difficult to process. Especially gelatines with high molecular mass are difficult or almost impossible to be pulverized by spray drying techniques, due to their high viscosity.
In the frame of this research work, an integrated high-pressure spraying, drying and pulverization process for high viscous gelatine was developed, based on a combination of the water removing effects "Evaporation" and "Gas-solubility". The resulting products were dry, free-flowing gelatine powders, still exhibiting high molecular masses. Due to the new, gentle method of processing, a completely new gelatine product with unique properties was obtained. Even the encapsulation of edible oil in high ratios was found to be possible with this new process. The characterisation was carried out by standard methods for gelatine on the one hand side, and standard procedures for characterising powders on the other hand side.
The developed process was patented under the identifier "WO 002009135601 A1".
Keywords: High Pressure Process, Supercritical Fluids, High molecular mass Gelatine, Micronisation, CO-2 - spray drying, Encapsulation, Gelatine Powder
Published in DKUM: 26.01.2011; Views: 3525; Downloads: 267
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83. Modifikacija pralnega stroja glede porabe vode : diplomsko deloUroš Ljubojević, 2008, undergraduate thesis Keywords: pralni stroj, doziranje vode, poraba vode, hidrostat, eng, washing machine, laundry machine, water filling, water consumption, pressure switch
Published in DKUM: 04.02.2009; Views: 3116; Downloads: 436
Full text (11,94 MB) |
