Equation of DNB Heat Flux for Upward Forced Flow of Cryogenic Liquids

Superconductivity Centennial Conference, SCC 2011 ; 18 September 2011 through 23 September 2011Knowledge of departure from nucleate boiling (DNB) heat flux is important for design of superconducting systems cooled by cryogenic liquids. We have already presented the equation of DNB heat flux that can describe the experimental data of liquid hydrogen. To see the applicability of the equation to other cryogenic liquids, similar heat transfer tests in forced flow of liquid nitrogen are performed for wide ranges of conditions in this work. It was confirmed that the DNB heat flux equation derived by the authors can express not only the data for liquid hydrogen but also those for liquid nitrogen

Aphids acquired symbiotic genes via lateral gene transfer

<p>Abstract</p> <p>Background</p> <p>Aphids possess bacteriocytes, which are cells specifically differentiated to harbour the obligate mutualist <it>Buchnera aphidicola </it>(γ-Proteobacteria). <it>Buchnera </it>has lost many of the genes that appear to be essential for bacterial life. From the bacteriocyte of the pea aphid <it>Acyrthosiphon pisum</it>, we previously identified two clusters of expressed sequence tags that display similarity only to bacterial genes. Southern blot analysis demonstrated that they are encoded in the aphid genome. In this study, in order to assess the possibility of lateral gene transfer, we determined the full-length sequences of these transcripts, and performed detailed structural and phylogenetic analyses. We further examined their expression levels in the bacteriocyte using real-time quantitative RT-PCR.</p> <p>Results</p> <p>Sequence similarity searches demonstrated that these fully sequenced transcripts are significantly similar to the bacterial genes <it>ldcA </it>(product, LD-carboxypeptidase) and <it>rlpA </it>(product, rare lipoprotein A), respectively. <it>Buchnera </it>lacks these genes, whereas many other bacteria, including <it>Escherichia coli</it>, a close relative of <it>Buchnera</it>, possess both <it>ldcA </it>and <it>rlpA</it>. Molecular phylogenetic analysis clearly demonstrated that the aphid <it>ldcA </it>was derived from a rickettsial bacterium closely related to the extant <it>Wolbachia </it>spp. (α-Proteobacteria, Rickettsiales), which are intracellular symbionts of various lineages of arthropods. The evolutionary origin of <it>rlpA </it>was not fully resolved, but it was clearly demonstrated that its double-ψ β-barrel domain is of bacterial origin. Real-time quantitative RT-PCR demonstrated that <it>ldcA </it>and <it>rlpA </it>are expressed 11.6 and 154-fold higher in the bacteriocyte than in the whole body, respectively. LdcA is an enzyme required for recycling murein (peptidoglycan), which is a component of the bacterial cell wall. As <it>Buchnera </it>possesses a cell wall composed of murein but lacks <it>ldcA</it>, a high level of expression of the aphid <it>ldcA </it>in the bacteriocyte may be essential to maintain <it>Buchnera</it>. Although the function of RlpA is not well known, conspicuous up-regulation of the aphid <it>rlpA </it>in the bacteriocyte implies that this gene is also essential for <it>Buchnera</it>.</p> <p>Conclusion</p> <p>In this study, we obtained several lines of evidence indicating that aphids acquired genes from bacteria via lateral gene transfer and that these genes are used to maintain the obligately mutualistic bacterium, <it>Buchnera</it>.</p

Psychological and weight-related characteristics of patients with anorexia nervosa-restricting type who later develop bulimia nervosa

<p>Abstract</p> <p>Background</p> <p>Patients with anorexia nervosa-restricting type (AN-R) sometimes develop accompanying bulimic symptoms or the full syndrome of bulimia nervosa (BN). If clinicians could predict who might change into the bulimic sub-type or BN, preventative steps could be taken. Therefore, we investigated anthropometric and psychological factors possibly associated with such changes.</p> <p>Method</p> <p>All participants were from a study by the Japanese Genetic Research Group for Eating Disorders. Of 80 patients initially diagnosed with AN-R, 22 changed to the AN-Binge Eating/Purging Type (AN-BP) and 14 to BN for some period of time. The remaining 44 patients remained AN-R only from the onset to the investigation period. Variables compared by ANOVA included anthropometric measures, personality traits such as Multiple Perfectionism Scale scores and Temperament and Character Inventory scores, and Beck Depression Inventory-II scores.</p> <p>Results</p> <p>In comparison with AN-R only patients, those who developed BN had significantly higher current BMI (p < 0.05) and maximum BMI in the past (p < 0.05). They also scored significantly higher for the psychological characteristic of parental criticism (p < 0.05) and lower in self-directedness (p < 0.05), which confirms previous reports, but these differences disappeared when the depression score was used as a co-variant. No significant differences were obtained for personality traits or depression among the AN-R only patients irrespective of their duration of illness.</p> <p>Conclusion</p> <p>The present findings suggest a tendency toward obesity among patients who cross over from AN-R to BN. Low self-directedness and high parental criticism may be associated with the development of BN by patients with AN-R, although the differences may also be associated with depression.</p

Film boiling heat transfer from a round wire to liquid hydrogen flowing upward in a concentric annulus

Proceedings of the 25th International Cryogenic Engineering Conference and International Cryogenic Materials Conference 2014Hydrogen film boiling heat transfer coefficients were measured for the heater surface superheats up to 400 K under pressures from 400 to 1100 kPa, liquid subcoolings from 0 to 11 K and flow velocities up to 7 m/s. The test wire used was 1.2 mm in diameter and 120 mm in length made of PtCo (0.5 wt.%) alloy, which was located at the center of 8 mm diameter conduit made of FRP (Fiber Reinforced Plastics). The heat transfer coefficients were higher for higher pressure, higher subcooling and higher flow velocity. The heat transfer coefficients were about 1.6 times higher than those predicted by Shiotsu-Hama equation for forced flow film boiling in a wide channel. Discussions were made on the mechanism of difference between them

Film boiling heat transfer properties of liquid hydrogen in natural convection

Proceedings of the 25th International Cryogenic Engineering Conference and International Cryogenic Materials Conference 2014Film boiling heat transfer properties of LH2 for various pressures and subcooling conditions were measured by applying electric current to give an exponential heat input to a PtCo wire with a diameter of 1.2 mm submerged in LH2. The heated wire was set to be horizontal to the ground. The heat transfer coefficient in the film boiling region was higher for higher pressure and higher subcooling. The experimental results are compared with the equation of pool film boiling heat transfer. It is confirmed that the pool film boiling heat transfer coefficients in LH2 can be expressed by this equation

DNB heat flux in forced convection of liquid hydrogen for a wire set in central axis of vertically mounted flow channel

Advances in Cryogenic Engineering: Proceedings of the Cryogenic Engineering Conference (CEC) 2017 (previous edition: CEC-2015) 9–13 July 2017, Madison, Wisconsin, USA.Liquid hydrogen has excellent physical properties, high latent heat and low viscosity of liquid, as a coolant for superconductors like MgB2. The knowledge of Departure from Nucleate Boiling (DNB) heat flux of liquid hydrogen is necessary for designing and cooling analysis of high critical temperature superconducting devices. In this paper, DNB heat fluxes of liquid hydrogen were measured under saturated and subcooled conditions at absolute pressures of 400, 700 and 1100 kPa for various flow velocities. Two wire test heaters made by Pt-Co alloy with the length of 200 mm and the diameter of 0.7 mm were used. And these round heaters were set in central axis of a flow channel made of Fiber Reinforced Plastic (FRP) with inner diameters of 8 mm and 12 mm. These test bodies were vertically mounted and liquid hydrogen flowed upward through the channel. From these experimental values, the correlations of DNB heat flux under saturated and subcooled conditions are presented in this paper

Forced flow boiling heat transfer properties of liquid hydrogen for manganin plate pasted on one side of a rectangular duct

Proceedings of the 25th International Cryogenic Engineering Conference and International Cryogenic Materials Conference 2014In this report, we show results on the forced flow boiling heat transfer experiments for manganin plate pasted on one side of a rectangular duct. Nucleate boiling heat transfer and its Departure from Nucleate Boiling (DNB) heat flux were measured for various pressures, subcooling and flow velocities. The DNB heat fluxes are higher for higher subcooling and higher flow velocity. The DNB heat fluxes were compared with the experimental data for round tube of nearly equal equivalent diameter. The DNB heat fluxes for the rectangular duct are lower than those for the round tube