New correlation to predict the heat transfer coefficient during in-tube cooling of turbulent supercritical CO2

The Nusselt number variations of supercritical carbon dioxide during in-tube cooling are presented and discussed. Using data presented in this paper as well as prior publications, a new correlation to predict the heat transfer coefficient of supercritical carbon dioxide during in-tube cooling has been developed. The new correlation is presented in this paper. It is based on mean Nusselt numbers that are calculated using the thermophysical properties at the wall and the bulk temperatures, respectively. It is seen that the majority of the numerical and experimental values are within ±20% of the values predicted by the new correlation.     

Purification, characterization and functional cloning of inositol oxygenase from Cryptococcus

The enzyme inositol oxygenase (myo-inositol : oxygen oxidoreductase; E.C. 1.13.99.1) is a monooxygenase that converts inositol into glucuronic acid in the presence of molecular oxygen. This enzyme is integrated into a pathway leading to either degradation and energy production or the biosynthesis of precursors for polysaccharides. The enzyme was purified from the yeast Cryptococcus lactativorus by a five-step chromatography procedure. The purified enzyme shows a molecular mass of 37 kDa on SDS-PAGE, similar to the estimation of the size of the native enzyme determined by size exclusion chromatography. Peptides of the inositol oxygenase protein derived from a tryptic digest were sequenced de novo by nanoelectrospray tandem mass spectrometry. Using degenerate oligonucleotides, the corresponding gene was cloned from first strand cDNA. The open reading frame encodes a 315 amino acid polypeptide with a predicted molecular mass of 36.9 kDa. Inositol oxygenase is a single copy gene in C. lactativorus. It has close homologues in other fungi such as Cryptococcus neoformans and Neurospora crassa. Biochemical characterization of the enzyme showed a pH optimum of 6-6.5 and a temperature optimum of 30 degrees C. Myo-inositol is the only accepted substrate with a Km of ca. 5 mM. The enzyme contains a Fe-centre but the enzyme activity is resistant to KCN.     

Abnormal early rearing and sexual responsiveness in male guinea pigs.

Examined in 4 experiments the role of early social experience in the discriminatory behavior of normally reared adult male guinea pigs, (N = 100), which court (circle and sway, mount, pelvic thrust) sexually unreceptive conspecifics but not usually members of other species. Ss weaned during the 1st week after birth were more likely to direct sexual responses to members of other species than were Ss weaned later. Among Ss weaned early, some social experience with a member of another species was usually necessary for individuals of that species to elicit sexual behavior, but the length of this experience and the period of development during which it must occur were flexible. It is concluded that early-weaned male guinea pigs are left with the potential to respond sexually to a wider range of stimuli than are normally reared individuals; the mechanisms by which this might occur are discussed. (39 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The inhomogeneous MUSIG model for the simulation of polydispersed flows

A generalized inhomogeneous multiple size group (MUSIG) model based on the Eulerian modeling framework was developed in close cooperation of ANSYS-CFX and Forschungszentrum Dresden-Rossendorf and implemented into the CFD code CFX. The model enables the subdivision of the dispersed phase into a number of size groups regarding the mass balance as well as regarding the momentum balance.

In this work, the special case of polydispersed bubbly flow is considered. By simulating such flows, the mass exchanged between bubble size classes by bubble coalescence and bubble fragmentation, as well as the momentum transfer between the bubbles and the surrounding liquid due to bubble size dependent interfacial forces have to be considered. Particularly the lift force has been proven to play an important role in establishing a certain bubble size distribution dependent flow regime.

In a previous study [Krepper, E., Lucas, D., Prasser, H.-M., 2005. On the modeling of bubbly flow in vertical pipes. Nucl. Eng. Des. 235, 597–611] the application of such effects were considered and justified and a general outline of such a model concept was given. In this paper the model and its validation for several vertical pipe flow situations is presented. The experimental data were obtained from the TOPFLOW test facility at the Forschungszentrum Dresden-Rossendorf (FZD). The wire-mesh technology measuring local gas volume fractions, bubble size distributions and velocities of gas and liquid phases were employed.

The inhomogeneous MUSIG model approach was shown as capable of describing bubbly flows with higher gas content. Particularly the separation phenomenon of small and large bubbles is well described. This separation has been proven as a key phenomenon in the establishment of the corresponding flow regime. Weaknesses in this approach can be attributed to the characterization of bubble coalescence and bubble fragmentation, which must be further investigated.     

Process Design in World 3.0 – Challenges and Strategies to Master the Raw Material Change

The evolution of global energy supply chains leads to a raw material change in the chemical industry. Despite this change, the value‐added chains of the chemical industry have to keep up their output of diverse high‐quality products desired by the customers. C1 chemistry in combination with suitable conversion technologies yielding olefins and aromatics will play a key role in mastering this challenge. New chemical value‐added chains have to be developed and assessed, resulting in an increasing importance of conceptual process design. All this will take place in what Ghemawat has called the World 3.0, a globally linked but regionally diverse world. This diversity creates further challenges for process design in the chemical industries. A systematic concept to address these challenges is given here, including strategies for optimization and decision support.     

Structuring in β-sitosterol + γ-oryzanol-based emulsion gels during various stages of a temperature cycle

Water-in-oil emulsions were prepared, structured only by a mixture of sitosterol and oryzanol and without further emulsifiers, containing 16 and 32% total sterol(esters)s on lipid phase and 10, 30 or 60% water. Previously, mixtures of β-sitosterol + γ-oryzanol were shown to form self-assembled tubules in triglyceride oil with diameter 7.2 ± 0.1 nm and a wall thickness 0.8 ± 0.2 nm. At 16% total sterol concentration, the SAXS diffraction patterns only demonstrate the presence of sitosterol and oryzanol crystals, but not of tubules. At 32% total sterol concentration, the diffraction patterns reveal the presence of tubules next to the crystals of the individual compounds. However, the tubule structure in these emulsions was more complicated than in pure oil and changed during storage, revealing the formation of bigger structures in the emulsion over time. In the cooling stage of a temperature cycle, water droplets nucleate at the tip of the fibres that reappear as a consequence of crystallisation.