Parametric effects on dryout of propane in a vertical circular mini-channel

This paper was presented at the 3rd Micro and Nano Flows Conference (MNF2011), which was held at the Makedonia Palace Hotel, Thessaloniki in Greece. The conference was organised by Brunel University and supported by the Italian Union of Thermofluiddynamics, Aristotle University of Thessaloniki, University of Thessaly, IPEM, the Process Intensification Network, the Institution of Mechanical Engineers, the Heat Transfer Society, HEXAG - the Heat Exchange Action Group, and the Energy Institute.This article presents dryout results of propane in a vertical circular mini channel made of stainless steel with an internal diameter of 1.70 mm and a heated length of 245 mm. The experiments are performed at three saturation temperatures of 23 degrees C, 33 degrees C and 43 degrees C. Mass flux is varied from 100 kg/m2s to 500 kg/m2s.The heat flux is increased in steps up to occurrence of dryout. The effect of different parameters such as mass flux, vapour quality and saturation temperature on the dryout heat flux is investigated. The results show that the dryout heat flux increases with the increase in mass flux and with the decrease of vapour quality. Almost no effect of saturation temperature on the dryout heat flux is observed. The generalised CHF correlations developed for macro and micro scale from the literature are compared with experimental results. Correlations developed by Callizo et al. (2008), Bowring (1972) and Katto and Ohno (1984) gave reasonably good predictions

Experimental investigation of two-phase pressure drop in a microchannel

This paper was presented at the 2nd Micro and Nano Flows Conference (MNF2009), which was held at Brunel University, West London, UK. The conference was organised by Brunel University and supported by the Institution of Mechanical Engineers, IPEM, the Italian Union of Thermofluid dynamics, the Process Intensification Network, HEXAG - the Heat Exchange Action Group and the Institute of Mathematics and its Applications.An experimental study of two-phase pressure drop in a horizontal circular microchannel is presented in this paper. Test tube is made of fused silica having an internal diameter of 781μm with a total length of 261mm and a heated length of 191mm.The external surface of the test tube is coated with an electrically conductive thin layer of ITO (Indium Tin Oxide) for direct heating of test section. Refrigerant R134a was used as the working fluid and mass flux during the experiments was varied from 100 to 650 kg/m2sec. Experiments were performed at a system pressure of 7.70 bar (corresponding to saturation temperature of 30oC). Two-phase frictional pressure drop characteristics with different mass flux, vapour fraction and heat flux were explored in detail. Finally, the prediction capability of well known available correlations in the literature, developed for macrochannels and others especially developed for microchannels was also checked. The homogeneous model predicts the data fairly well with a mean absolute deviation (MAD) of 19% and 69% of data within ±20% error band. The Müller-Steinhagen and Heck (1986) correlation developed for macrochannels predicts the data with a MAD of 19% and 61% of data within ±20% error band. The Mishima and Hibiki (1996) correlation, developed for microchannels, also shows fairly good approximation of the data with MAD of 19% and 57% of data within ±20% error band

Reference values of whole-blood fatty acids by age and sex from European children aged 3-8 years

OBJECTIVES: To establish reference values for fatty acids (FA) especially for n-3 and n-6 long-chain polyunsaturated FAs (LC PUFA) in whole-blood samples from apparently healthy 3-8-year-old European children. The whole-blood FA composition was analysed and the age-and sex-specific distribution of FA was determined. DESIGN AND SUBJECTS: Blood samples for FA analysis were taken from 2661 children of the IDEFICS (identification and prevention of dietary-and lifestyle-induced health effects in children and infants) study cohort. Children with obesity (n = 454) and other diseases that are known to alter the FA composition (n = 450) were excluded leaving 1653 participants in the reference population. MEASUREMENTS: The FA composition of whole blood was analysed from blood drops by a rapid, validated gas chromatographic method. RESULTS: Pearson correlation coefficients showed an age-dependent increase of C18:2n-6 and a decrease of C18:1n-9 in a subsample of normal weight boys and girls. Other significant correlations with age were weak and only seen either in boys or in girls, whereas most of the FA did not show any age dependence. For age-dependent n-3 and n-6 PUFA as well as for other FA that are correlated with age (16:0, C18:0 and C18:1n-9) percentiles analysed with the general additive model for location scale and shape are presented. A higher median in boys than in girls was observed for C20:3n-6, C20:4n-6 and C22:4n-6. CONCLUSIONS: Given the reported associations between FA status and health-related outcome, the provision of FA reference ranges may be useful for the interpretation of the FA status of children in epidemiological and clinical studies

The effects of methionine acquisition and synthesis on Streptococcus pneumoniae growth and virulence

Extent: 14 p.Bacterial pathogens need to acquire nutrients from the host, but for many nutrients their importance during infection remain poorly understood. We have investigated the importance of methionine acquisition and synthesis for Streptococcus pneumoniae growth and virulence using strains with gene deletions affecting a putative methionine ABC transporter lipoprotein (Sp_0149, metQ) and/or methionine biosynthesis enzymes (Sp_0585 - Sp_0586, metE and metF). Immunoblot analysis confirmed MetQ was a lipoprotein and present in all S. pneumoniae strains investigated. However, vaccination with MetQ did not prevent fatal S. pneumoniae infection in mice despite stimulating a strong specific IgG response. Tryptophan fluorescence spectroscopy and isothermal titration calorimetry demonstrated that MetQ has both a high affinity and specificity for L-methionine with a KD of ~ 25 nM, and a DmetQ strain had reduced uptake of C14-methionine. Growth of the ΔmetQ/ΔmetEF strain was greatly impaired in chemically defined medium containing low concentrations of methionine and in blood but was partially restored by addition of high concentrations of exogenous methionine. Mixed infection models showed no attenuation of the ΔmetQ, ΔmetEF and ΔmetQ/DmetEF strains in their ability to colonise the mouse nasopharnyx. In a mouse model of systemic infection although significant infection was established in all mice, there were reduced spleen bacterial CFU after infection with the ΔmetQ/ΔmetEF strain compared to the wild-type strain. These data demonstrate that Sp_0149 encodes a high affinity methionine ABC transporter lipoprotein and that Sp_0585 – Sp_0586 are likely to be required for methionine synthesis. Although Sp_0149 and Sp_0585-Sp_0586 make a contribution towards full virulence, neither was essential for S. pneumoniae survival during infection.Shilpa Basavanna, Suneeta Chimalapati, Abbas Maqbool, Bruna Rubbo, Jose Yuste, Robert J. Wilson, Arthur Hosie, Abiodun D. Ogunniyi, James C. Paton, Gavin Thomas and Jeremy S. Brow

RNA-Seq of Human Neurons Derived from iPS Cells Reveals Candidate Long Non-Coding RNAs Involved in Neurogenesis and Neuropsychiatric Disorders

Genome-wide expression analysis using next generation sequencing (RNA-Seq) provides an opportunity for in-depth molecular profiling of fundamental biological processes, such as cellular differentiation and malignant transformation. Differentiating human neurons derived from induced pluripotent stem cells (iPSCs) provide an ideal system for RNA-Seq since defective neurogenesis caused by abnormalities in transcription factors, DNA methylation, and chromatin modifiers lie at the heart of some neuropsychiatric disorders. As a preliminary step towards applying next generation sequencing using neurons derived from patient-specific iPSCs, we have carried out an RNA-Seq analysis on control human neurons. Dramatic changes in the expression of coding genes, long non-coding RNAs (lncRNAs), pseudogenes, and splice isoforms were seen during the transition from pluripotent stem cells to early differentiating neurons. A number of genes that undergo radical changes in expression during this transition include candidates for schizophrenia (SZ), bipolar disorder (BD) and autism spectrum disorders (ASD) that function as transcription factors and chromatin modifiers, such as POU3F2 and ZNF804A, and genes coding for cell adhesion proteins implicated in these conditions including NRXN1 and NLGN1. In addition, a number of novel lncRNAs were found to undergo dramatic changes in expression, one of which is HOTAIRM1, a regulator of several HOXA genes during myelopoiesis. The increase we observed in differentiating neurons suggests a role in neurogenesis as well. Finally, several lncRNAs that map near SNPs associated with SZ in genome wide association studies also increase during neuronal differentiation, suggesting that these novel transcripts may be abnormally regulated in a subgroup of patients

Lunapark deficiency leads to an autosomal recessive neurodevelopmental phenotype with a degenerative course, epilepsy and distinct brain anomalies.

LNPK encodes a conserved membrane protein that stabilizes the junctions of the tubular endoplasmic reticulum network playing crucial roles in diverse biological functions. Recently, homozygous variants in LNPK were shown to cause a neurodevelopmental disorder (OMIM#618090) in four patients displaying developmental delay, epilepsy and nonspecific brain malformations including corpus callosum hypoplasia and variable impairment of cerebellum. We sought to delineate the molecular and phenotypic spectrum of LNPK-related disorder. Exome or genome sequencing was carried out in 11 families. Thorough clinical and neuroradiological evaluation was performed for all the affected individuals, including review of previously reported patients. We identified 12 distinct homozygous loss-of-function variants in 16 individuals presenting with moderate to profound developmental delay, cognitive impairment, regression, refractory epilepsy and a recognizable neuroimaging pattern consisting of corpus callosum hypoplasia and signal alterations of the forceps minor ('ear-of-the-lynx' sign), variably associated with substantia nigra signal alterations, mild brain atrophy, short midbrain and cerebellar hypoplasia/atrophy. In summary, we define the core phenotype of LNPK-related disorder and expand the list of neurological disorders presenting with the 'ear-of-the-lynx' sign suggesting a possible common underlying mechanism related to endoplasmic reticulum-phagy dysfunction