523 research outputs found

    Theoretical study of Oldroyd-b visco-elastic fluid flow through curved pipes with slip effects in polymer flow processing

    Get PDF
    The characteristics of the flow field of both viscous and viscoelastic fluids passing through a curved pipe with a Navier slip boundary condition have been investigated analytically in the present study. The Oldroyd-B constitutive equation is employed to simulate realistic transport of dilute polymeric solutions in curved channels. In order to linearize the momentum and constitutive equations, a perturbation method is used in which the ratio of radius of cross section to the radius of channel curvature is employed as the perturbation parameter. The intensity of secondary and main flows is mainly affected by the hoop stress and it is demonstrated in the present study that both the Weissenberg number (the ratio of elastic force to viscous force) and slip coefficient play major roles in determining the strengths of both flows. It is also shown that as a result of an increment in slip coefficient, the position of maximum velocity markedly migrates away from the pipe center towards the outer side of curvature. Furthermore, results corresponding to Navier slip scenarios exhibit non-uniform distributions in both the main and lateral components of velocity near the wall which can notably vary from the inner side of curvature to the outer side. The present solution is also important in polymeric flow processing systems because of experimental evidence indicating that the no-slip condition can fail for these flows, which is of relevance to chemical engineers

    Exposure of neonatal rats to maternal cafeteria feeding during suckling alters hepatic gene expression and DNA methylation in the insulin signalling pathway

    Get PDF
    Nutrition in early life is a determinant of lifelong physiological and metabolic function. Diseases that are associated with ageing may, therefore, have their antecedents in maternal nutrition during pregnancy and lactation. Rat mothers were fed either a standard laboratory chow diet (C) or a cafeteria diet (O) based upon a varied panel of highly palatable human foods, during lactation. Their offspring were then weaned onto chow or cafeteria diet giving four groups of animals (CC, CO, OC, OO n=9-10). Livers were harvested 10 weeks post-weaning for assessment of gene and protein expression, and DNA methylation. Cafeteria feeding post-weaning impaired glucose tolerance and was associated with sex-specific altered mRNA expression of peroxisome proliferator activated receptor gamma (PPARg) and components of the insulin-signalling pathway (Irs2, Akt1 and IrB). Exposure to the cafeteria diet during the suckling period modified the later response to the dietary challenge. Post-weaning cafeteria feeding only down-regulated IrB when associated with cafeteria feeding during suckling (group OO, interaction of diet in weaning and lactation P=0.041). Responses to cafeteria diet during both phases of the experiment varied between males and females. Global DNA methylation was altered in the liver following cafeteria feeding in the post-weaning period, in males but not females. Methylation of the IrB promoter was increased in group OC, but not OO (P=0.036). The findings of this study add to a growing evidence base that suggests tissue function across the lifespan a product of cumulative modifications to the epigenome and transcriptome, which may be both tissue and sex-specific

    Observation of a ppb mass threshoud enhancement in \psi^\prime\to\pi^+\pi^-J/\psi(J/\psi\to\gamma p\bar{p}) decay

    Full text link
    The decay channel ψπ+πJ/ψ(J/ψγppˉ)\psi^\prime\to\pi^+\pi^-J/\psi(J/\psi\to\gamma p\bar{p}) is studied using a sample of 1.06×1081.06\times 10^8 ψ\psi^\prime events collected by the BESIII experiment at BEPCII. A strong enhancement at threshold is observed in the ppˉp\bar{p} invariant mass spectrum. The enhancement can be fit with an SS-wave Breit-Wigner resonance function with a resulting peak mass of M=186113+6(stat)26+7(syst)MeV/c2M=1861^{+6}_{-13} {\rm (stat)}^{+7}_{-26} {\rm (syst)} {\rm MeV/}c^2 and a narrow width that is Γ<38MeV/c2\Gamma<38 {\rm MeV/}c^2 at the 90% confidence level. These results are consistent with published BESII results. These mass and width values do not match with those of any known meson resonance.Comment: 5 pages, 3 figures, submitted to Chinese Physics

    Measurement of the matrix element for the decay η′→ηπ +π -

    Get PDF
    The Dalitz plot of η⊃′→ηπ⊃+π⊃- decay is studied using (225.2±2.8)×106 J/ψ events collected with the BESIII detector at the BEPCII e⊃+e⊃- collider. With the largest sample of η⊃′ decays to date, the parameters of the Dalitz plot are determined in a generalized and a linear representation. Also, the branching fraction of J/ψ→γη⊃′ is determined to be (4.84±0.03±0.24)×10⊃-3, where the first error is statistical and the second systematic. © 2011 American Physical Society.published_or_final_versio

    Efficacy and Safety of General Anesthesia Induction with Ciprofol in Hip Fracture Surgery of Elderly Patients: A Randomized Controlled Trial

    Get PDF
    Yan-fei Lu,1,&ast; Ji-min Wu,2,&ast; Hai-yan Lan,2 Qiao-min Xu,2 Shu-qi Shi,2 Gong-chen Duan2 1Center for Rehabilitation Medicine, Department of Anesthesiology, Zhejiang Provincial People’s Hospital, Affiliated People’s Hospital, Hangzhou Medical College, Hangzhou, People’s Republic of China; 2Department of Anesthesiology, Lishui People’s Hospital, Wenzhou Medical University Lishui Hospital, Lishui, People’s Republic of China&ast;These authors contributed equally to this workCorrespondence: Gong-chen Duan, Department of Anesthesiology, Lishui People’s Hospital, Wenzhou Medical University Lishui Hospital, No. 1188, Liyang Street, Lishui, Zhejiang, 323000, People’s Republic of China, Tel/Fax +8618957093030, Email [email protected]: Ciprofol is a new intravenous sedative / anesthetic drug. In recent years, many clinical studies have also confirmed the sedative effect of ciprofol. However, more clinical research is still needed on its clinical application characteristics in special populations.Objective: The aim of this study was to compare the clinical effects of ciprofol and propofol in general anesthesia induction of elderly patients.Methods: 60 elderly (aged ≥ 75 years) patients underwent hip fracture surgery were randomly into two groups of a 1:1 ratio. Group C (ciprofol group): 0.3mg/kg ciprofol was infused. Group P (propofol group): 1.5mg/kg propofol was infused. The observation period was from the infusion of test drug to 5 min after endotracheal intubation. The primary outcomes included the incidence of severe hypotension and hypotension during the observation period. The secondary outcomes were as follows: the success rate of general anesthesia induction, the number of additional sedation, the time of loss of consciousness (LOC), Δ MAP, Δ HR, adverse events and the frequency of vasoactive drugs used.Results: Finally, 60 subjects completed the study. Compared with Group P, the incidence of severe hypotension in Group C was lower (26.7% vs 53.3%, P = 0.035), the incidence of hypotension was also lower (36.7% vs 63.3%, P = 0.037), Δ MAP in Group C was significantly lower (31.4 ± 11.4 vs 39.6 ± 15.7, P = 0.025), the frequency of ephedrine used and the incidence of injection pain in Group C were also significantly lower.Conclusion: Ciprofol showed similar efficacy to propofol when used for general anesthesia induction in elderly patients underwent hip fracture surgery and could maintain more stable blood pressure.Keywords: Ciprofol, elderly, Hip fracture surgery, general anesthesia, hypotensio

    Field Emission Properties and Fabrication of CdS Nanotube Arrays

    Get PDF
    A large area arrays (ca. 40 cm2) of CdS nanotube on silicon wafer are successfully fabricated by the method of layer-by-layer deposition cycle. The wall thicknesses of CdS nanotubes are tuned by controlling the times of layer-by-layer deposition cycle. The field emission (FE) properties of CdS nanotube arrays are investigated for the first time. The arrays of CdS nanotube with thin wall exhibit better FE properties, a lower turn-on field, and a higher field enhancement factor than that of the arrays of CdS nanotube with thick wall, for which the ratio of length to the wall thickness of the CdS nanotubes have played an important role. With increasing the wall thickness of CdS nanotube, the enhancement factorβdecreases and the values of turn-on field and threshold field increase

    Gene therapy for monogenic liver diseases: clinical successes, current challenges and future prospects

    Get PDF
    Over the last decade, pioneering liver-directed gene therapy trials for haemophilia B have achieved sustained clinical improvement after a single systemic injection of adeno-associated virus (AAV) derived vectors encoding the human factor IX cDNA. These trials demonstrate the potential of AAV technology to provide long-lasting clinical benefit in the treatment of monogenic liver disorders. Indeed, with more than ten ongoing or planned clinical trials for haemophilia A and B and dozens of trials planned for other inherited genetic/metabolic liver diseases, clinical translation is expanding rapidly. Gene therapy is likely to become an option for routine care of a subset of severe inherited genetic/metabolic liver diseases in the relatively near term. In this review, we aim to summarise the milestones in the development of gene therapy, present the different vector tools and their clinical applications for liver-directed gene therapy. AAV-derived vectors are emerging as the leading candidates for clinical translation of gene delivery to the liver. Therefore, we focus on clinical applications of AAV vectors in providing the most recent update on clinical outcomes of completed and ongoing gene therapy trials and comment on the current challenges that the field is facing for large-scale clinical translation. There is clearly an urgent need for more efficient therapies in many severe monogenic liver disorders, which will require careful risk-benefit analysis for each indication, especially in paediatrics
    corecore