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Experimental Investigation of micro Heat Pipes of Different Cross-Sections Having Same Hydraulic Diameter

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Journal of Thermal Science 2008年第3期17卷 247-252页

作者： S.l.mahmood m.A.R.Akhanda Department of mechanical and Chemical Engineering Islamic University of Technology

Effects of micro heat pipe （mHP） cross-sections and orientations on its thermal performance are experimentally investigated in this study. Tests are conducted using five different cross-sections （circular, semicircular, elliptical, semi-elliptical and rectangular） of micro heat pipes having same hydraulic diameter of 3 rnm placed at three different inclination angles （0°, 45°, 90°）, where water is used as the working fluid. Evaporator section of the mHP is heated by an electric heater and the condenser section is cooled by circulation of water in an annular space between condenser section and the water jacket. Temperatures at different locations of the mHP are measured using five calibrated K type thermocouples. Heat supply is varied using a voltage regulator which is measured by a precision ammeter and a voltmeter. It is found that thermal performance tends to deteriorate as the mHP is flattened. Thus among all cross-sections of mHP, circular one exhibits the best thermal performance in terms of heat flux dissipation followed by semi-elliptical, semi-circular, elliptical and rectangular cross-sections. moreover, its heat transfer capability also decreases with decreasing of its inclination angle. Finally, a correlation is developed which covers all the experimental data within ＋7%.

关键词： micro heat pipe cross-section hydraulic diameter inclination.

Do concentrations in eggs and liver tissue tell the same story of temporal trends of mercury in high Arctic seabirds?

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Journal of Environmental Sciences 2018年第6期30卷 65-72页

作者： mark l.mallory Birgit m.Braune Biology Department Acadia University Environment and Climate Change Canada National Wildlife Research Centre Carleton University

mercury（Hg） remains a key contaminant of concern in Arctic biota, and monitoring of Hg concentrations in seabird tissues will be an effective approach to track the effects of implementing the minamata Convention. We examined trends in total Hg（THg） in liver and egg tissues of two Arctic seabirds, thick-billed murres（Uria lomvia） and northern fulmars（Fulmarus glacialis）, between 1976 and 2013 to assess whether both tissues showed similar patterns of Hg change. Hepatic THg was consistently higher than egg THg, and both species had similar egg THg concentrations, but fulmars had higher hepatic THg than *** THg concentrations showed more relative variation through time than *** suggest that egg THg better reflects exposure of birds to THg in local, Arctic prey,whereas liver THg may incorporate longer term, year-round THg exposure. Additional analysis of THg distribution in Arctic seabirds post-laying would help inform interpretation of long-term trends.

关键词： Canada Fulmarus glacialis Northern fulmar Thick-billed murre Uria lomvia

Spent coffee grounds as a renewable source of energy: An analysis of bulk powder flowability

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Particuology 2019年第2期17卷 92-100页

作者： l. massaro Sousa m.C. Ferreira Drying Center for Pastes Suspensions and Seeds. Chemical Engineering Department Federal University of Sao Carlos. P.O. Box 676 13565-905 Sao Carlos Brazil

The main use for spent coffee grounds (SCG) produced in the soluble coffee industry is thermal energy generation in the industry itself. The SCG are processed using operations that are strongly dependent on powder flow behavior. In this study, we evaluated two classical flowability in dices of non-consolidated SCG powders: the angle of repose (AoR), and the Hausner ratio (HR). The influences of the mean particle diameter, particle size distribution (PSD), and water content on the AoR and HR values of SCG were analyzed for powders with a mean particle size range of 225-550 μm. For powders with a mean particle size close to 350 μm and for mixtures containing more than 40% fine particles, the HR (>1.35) and AoR (>45 °) values were characteristic of poor flowability. The AoR was sensitive to the powder PSD, and powders with similar mean particle sizes had higher AoR values when the PSD was larger. For powders w让h water contents up to 50%, the flowability indices were not greatly affected by the water content. A modified linear-mixture packing model was used to predict the packed bed void fractions for binary and ternary mixtures of the three base powders. The model was used to construct a ternary diagram to estimate the HR values of the mixtures. An equation was fitted to correlate HR and AoR. The proposed diagram and the equation provide insight into flow behavior and could be used for process design of industrial plants that handle SCG.

关键词： Spent coffee ground Biomass Flowability Hausner ratio Angle of repose

DNS in evolution of vorticity and sign relationship in wake transition of a circular cylinder:(pure)mode A

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Acta mechanica Sinica 2019年第6期35卷 1131-1149页

作者： l.m.lin Z.R.Tan Key laboratory for mechanics in Fluid Solid Coupling Systems Institute of MechanicsChinese Academy of SciencesBeijing 100190China School of Navigation Wuhan University of TechnologyWuhan 430063China Hubei Key laboratory of Inland Shipping Technology Wuhan University of TechnologyWuhan 430063China

In the present paper,the spatio-temporal evolution of vorticity in the first wake instability,i.e.,(pure)mode A,is investigated in order to understand the wake vortex dynamics and sign relationships among vorticity *** numerical simulation(DNS)for the flow past a circular cylinder is performed,typically at a Reynolds number of 200,in the three-dimensional(3-D)wake *** to characteristics of time histories of fluid forces,three different stages are identified as the computational transition,the initial stage and fully developed *** the second initial stage,the original two-dimensional spanwise vortices become obviously three-dimensional associated with the streamwise or vertical vorticity intensified up to about *** a matter of fact,these additional vorticities,caused by the intrinsic 3-D instability,are already generated firstly on cylinder surfaces early in the computational transition,indicating that the three-dimensionality appeared early near the *** evolution of additional components of vorticity with features the same as mode A shows that(pure)mode A can be already formed in the late computational *** careful analysis of the vorticity field on the front surface,in the shear layers and near wake at typical times,two sign laws are *** illustrate intrinsic relationships among three vorticity components,irrelevant to the wavelength or Fourier mode and Reynolds number in(pure)mode *** importantly,the origin of streamwise vortices is found and explained by a new physical mechanism based on the theory of vortex-induced *** a result,the whole process of formation and shedding vortices with these vorticities is firstly and completely *** characteristics are presented in detail.

关键词： Wake transition Circular cylinder Vorticity mode A Sign law

Regulator of G protein signaling 6 mediates exercise-induced recovery of hippocampal neurogenesis,learning,and memory in a mouse model of Alzheimer’s disease

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Neural Regeneration Research 2025年第10期20卷 2969-2981页

作者： mackenzie m.Spicer Jianqi Yang Daniel Fu Alison N.DeVore marisol lauffer Nilufer S.Atasoy Deniz Atasoy Rory A.Fisher Department of Neuroscience and Pharmacology University of Iowa Carver College of MedicineIowa CityIAUSA Iowa Neuroscience Institute University of Iowa Carver College of MedicineIowa CityIAUSA Interdisciplinary Graduate Program in molecular medicine University of Iowa Carver College of MedicineIowa CityIAUSA Neural Circuits and Behavior Core University of Iowa Carver College of MedicineIowa CityIAUSA

Hippocampal neuronal loss causes cognitive dysfunction in Alzheimer’s *** hippocampal neurogenesis is reduced in patients with Alzheimer’s *** stimulates adult hippocampal neurogenesis in rodents and improves memory and slows cognitive decline in patients with Alzheimer’s ***,the molecular pathways for exercise-induced adult hippocampal neurogenesis and improved cognition in Alzheimer’s disease are poorly ***,regulator of G protein signaling 6(RGS6)was identified as the mediator of voluntary running-induced adult hippocampal neurogenesis in ***,we generated novel RGS6fl/fl;APP_(SWE) mice and used retroviral approaches to examine the impact of RGS6 deletion from dentate gyrus neuronal progenitor cells on voluntary running-induced adult hippocampal neurogenesis and cognition in an amyloid-based Alzheimer’s disease mouse *** found that voluntary running in APP_(SWE) mice restored their hippocampal cognitive impairments to that of control *** cognitive rescue was abolished by RGS6 deletion in dentate gyrus neuronal progenitor cells,which also abolished running-mediated increases in adult hippocampal *** hippocampal neurogenesis was reduced in sedentary APP_(SWE) mice versus control mice,with basal adult hippocampal neurogenesis reduced by RGS6 deletion in dentate gyrus neural precursor ***6 was expressed in neurons within the dentate gyrus of patients with Alzheimer’s disease with significant loss of these RGS6-expressing ***,RGS6 mediated voluntary running-induced rescue of impaired cognition and adult hippocampal neurogenesis in APP_(SWE) mice,identifying RGS6 in dentate gyrus neural precursor cells as a possible therapeutic target in Alzheimer’s disease.

关键词： adult hippocampal neurogenesis Alzheimer’s disease dentate gyrus exercise learning/memory neural precursor cells regulator of G protein signaling 6(RGS6)

hsa-mir-183 is frequently methylated and related to poor survival in human hepatocellular carcinoma

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World Journal of Gastroenterology 2017年第9期23卷 1568-1575页

作者： Sumadi lukman Anwar Till Krech Britta Hasemeier Elisa schipper Nora Schweitzer Arndt Vogel Hans Kreipe Reena Buurman Britta Skawran Ulrich lehmann Ulrich lehmann Institute of PathologyMedizinische Hochschule Hannover Department of Surgery Faculty of Medicine Universitas Gadjah Mada Department of Gastroenterology Hepatology and EndocrinologyMedizinische Hochschule Hannover Institute of Human Genetics Medizinische Hochschule Hannover

To screen clinically relevant microRNAs (miRNAs) silenced by DNA methylation in human hepatocellular carcinoma (HCC).mETHODSKnockdown of DNA methyltransferases (DNmTs) using siRNAs and miRNA profiling in HCC cell lines were performed to identify DNA hypermethylation-mediated miRNA downregulation. Confirmation using individual quantitative real-time PCR (qRT-PCR) assays was then performed followed by DNA methylation quantification at the promoter of the miRNA genes. Quantification of DNA methylation and miRNA expression was then performed in primary HCC tumor samples and related with clinicopathological *** profiling after DNmT knockdown in HCC cell lines revealed upregulation of miR-23, miR-25 and miR-183. After qRT-PCR confirmation and CpG island methylation quantification of these miRNAs in cell lines, further analysis in primary HCC specimens showed that hsa-miR-183 is hypermethylated in 30% of HCC (n = 40). Expression of mature miR-183 showed an inverse correlation with DNA methylation levels. In HCC cells, DNmT knockdown and 5-aza-2’-deoxycytidine treatment reduced methylation and stimulated expression of miR-183. In HCC patients, hypermethylation at hsa-miR-183 promoter significantly correlates with poor survival (log-rank test P = 0.03). DNA methylation analysis in healthy liver, benign liver tumors (hepatocellular adenoma and focal nodular hyperplasia) and their corresponding adjacent tissues showed absence of hypermethylation supporting the notion that aberrant methylation at hsa-miR-183 is specific for the malignant transformation of *** data indicate that hypermethylation of hsa-miR-183 is a frequent event in HCC and potentially useful as a novel surrogate diagnostic and prognostic marker.

关键词： hsa-miR-183 DNA methylation DNmT knockdown microRNA microarray

mechanical stress and deformation analyses of pressurized cylindrical shells based on a higher-order modeling

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Defence Technology（防务技术） 2023年第2期20卷 24-33页

作者： S.mannani l.Collini m.Arefi Department of Solid mechanic Faculty of Mechanical EngineeringUniversity of KashanKashan87317-51167Iran Department of Engineering and Architecture University of ParmaParco Area Delle Scienze 181/A43124ParmaItaly

In this research,mechanical stress,static strain and deformation analyses of a cylindrical pressure vessel subjected to mechanical loads are *** kinematic relations are developed based on higherorder sinusoidal shear deformation *** stretching formulation is accounted for more accurate *** total transverse deflection is divided into bending,shear and thickness stretching parts in which the third term is responsible for change of deflection along the thickness *** axisymmetric formulations are derived through principle of virtual work.A parametric study is presented to investigate variation of stress and strain components along the thickness and longitudinal *** explore effect of thickness stretching model on the static results,a comparison between the present results with the available results of literature is *** an important output,effect of micro-scale parameter is studied on the static stress and strain distribution.

关键词： Principle of virtual work Thickness-stretched and shear deformable model Stress and strain analyses Cylindrical pressure vessel

Cr（V）involvementin the toxicity pathway of testicular damage

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Asian Journal of Andrology 2002年第2期4卷 153-155页

作者： m.l.Pereira T.m.Santos 等 DepartmentofBiology Departmentofchemistry UniversityofAveriro3810－193AveiroPortugal

AIm:The functional integrity of the blood-testis barrier (BTB) in male mice exposed to Cr(V) was studied in order to clarify the mechanism underlying testicular injury.mETHODS:Adult male mice were subcutaneously injected repeated doses of 8.02 micromol (0.5 ml) of Cr/*** for 5 days. Animals receiving a similar volume of bis(hydroxyethyl)-aminotris(hydroxymethyl)methane buffer (BT) were used as controls. The animals were sacrificed on day 6 and small fragments of seminiferous tubules, approximately 8-10 mm length, were incised and sutured at both ends. They were exposed in vitro to horseradish peroxidase-containing culture medium for 10 minutes. Tissues were then fixed and processed for ultrastructural studies.RESUlTS:Controls and Cr(V)-treated group resulted in the uptake of the tracer by Sertoli cells. However, the major finding consisted in the permeability of the BTB only in the Cr(V)-group, as evidenced by the presence of the tracer within the junctions between the neighbouring Sertoli cells.CONClUSION:The BTB is disrupted in mice submitted to Cr(V). The permeability of the BTB is a crucial feature to be investigated for the understanding of lesions within the seminiferous tubule.

关键词： Blood-testis barrier Cr(V) Horseradish peroxidase Integrity Spermatogenesis

Numerical modelling Point-to-Plane of Negative Corona Discharge in N_2 Under Non-Uniform Electric Field

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Plasma Science and Technology 2015年第6期17卷 469-474页

作者： A.K.FEROUANI m.lEmERINI l.mERAD m.HOUAlEF Ecole Préparatoire en Sciences et Techniques Département de Physique lPT Université A.BelkaidFaculté des SciencesDépartement de Physique Ecole Préparatoire en Sciences et Techniques Département de Maths

The paper presents a simulation model of the negative corona discharge in N2 under various pressures. The simulated discharge is of a negative point-to-plane mass type, with an inter-electrode separation distance of 20 mm and a symmetry about the axis of discharge. This simulation investigates the behavior of the neutral density and temperature for different pressures in the range of 0.1-10.0 bar. The spatial and temporal evolution of the neutral gas is analyzed based upon the equations of continuity, momentum and energy in a two-dimensional cylindrical geometry model. For that geometry of the system, the FCT （Flux Corrected Transport） technique was adopted. The results show that the pressure plays a significant role of the neutrals dynamics.

关键词： DC corona discharge FCT method numerical simulation