Reliability characteristics and conduction mechanisms in resistive switching memory devices using ZnO thin films

In this work, bipolar resistive switching characteristics were demonstrated in the Pt/ZnO/Pt structure. Reliability tests show that ac cycling endurance level above 106 can be achieved. However, significant window closure takes place after about 102 dc cycles. Data retention characteristic exhibits no observed degradation after 168 h. Read durability shows stable resistance states after 106 read times. The current transportation in ZnO films is dominated by the hopping conduction and the ohmic conduction in high-resistance and low-resistance states, respectively. Therefore, the electrical parameters of trap energy level, trap spacing, Fermi level, electron mobility, and effective density of states in conduction band in ZnO were identified

Unravelling the effects of age, period and cohort on metabolic syndrome components in a Taiwanese population using partial least squares regression

<p>Abstract</p> <p>Background</p> <p>We investigate whether the changing environment caused by rapid economic growth yielded differential effects for successive Taiwanese generations on 8 components of metabolic syndrome (MetS): body mass index (BMI), systolic blood pressure (SBP), diastolic blood pressure (DBP), fasting plasma glucose (FPG), triglycerides (TG), high-density lipoprotein (HDL), Low-density lipoproteins (LDL) and uric acid (UA).</p> <p>Methods</p> <p>To assess the impact of age, birth year and year of examination on MetS components, we used partial least squares regression to analyze data collected by Mei-Jaw clinics in Taiwan in years 1996 and 2006. Confounders, such as the number of years in formal education, alcohol intake, smoking history status, and betel-nut chewing were adjusted for.</p> <p>Results</p> <p>As the age of individuals increased, the values of components generally increased except for UA. Men born after 1970 had lower FPG, lower BMI, lower DBP, lower TG, Lower LDL and greater HDL; women born after 1970 had lower BMI, lower DBP, lower TG, Lower LDL and greater HDL and UA. There is a similar pattern between the trend in levels of metabolic syndrome components against birth year of birth and economic growth in Taiwan.</p> <p>Conclusions</p> <p>We found cohort effects in some MetS components, suggesting associations between the changing environment and health outcomes in later life. This ecological association is worthy of further investigation.</p

Performance evaluation on an air-cooled heat exchanger for alumina nanofluid under laminar flow

This study analyzes the characteristics of alumina (Al2O3)/water nanofluid to determine the feasibility of its application in an air-cooled heat exchanger for heat dissipation for PEMFC or electronic chip cooling. The experimental sample was Al2O3/water nanofluid produced by the direct synthesis method at three different concentrations (0.5, 1.0, and 1.5 wt.%). The experiments in this study measured the thermal conductivity and viscosity of nanofluid with weight fractions and sample temperatures (20-60°C), and then used the nanofluid in an actual air-cooled heat exchanger to assess its heat exchange capacity and pressure drop under laminar flow. Experimental results show that the nanofluid has a higher heat exchange capacity than water, and a higher concentration of nanoparticles provides an even better ratio of the heat exchange. The maximum enhanced ratio of heat exchange and pressure drop for all the experimental parameters in this study was about 39% and 5.6%, respectively. In addition to nanoparticle concentration, the temperature and mass flow rates of the working fluid can affect the enhanced ratio of heat exchange and pressure drop of nanofluid. The cross-section aspect ratio of tube in the heat exchanger is another important factor to be taken into consideration

Sex difference in the association of metabolic syndrome with high sensitivity C-reactive protein in a Taiwanese population

<p>Abstract</p> <p>Background</p> <p>Although sex differences have been reported for associations between components of metabolic syndrome and inflammation, the question of whether there is an effect modification by sex in the association between inflammation and metabolic syndrome has not been investigated in detail. Therefore, the aim of this study was to compare associations of high sensitivity C-creative protein (hs-CRP) with metabolic syndrome and its components between men and women.</p> <p>Methods</p> <p>A total of 1,305 subjects aged 40 years and over were recruited in 2004 in a metropolitan city in Taiwan. The biochemical indices, such as hs-CRP, fasting glucose levels, lipid profiles, urinary albumin, urinary creatinine and anthropometric indices, were measured. Metabolic syndrome was defined using the American Heart Association and the National Heart, lung and Blood Institute (AHA/NHLBI) definition. The relationship between metabolic syndrome and hs-CRP was examined using multivariate logistic regression analysis.</p> <p>Results</p> <p>After adjustment for age and lifestyle factors including smoking, and alcohol intake, elevated concentrations of hs-CRP showed a stronger association with metabolic syndrome in women (odds ratio comparing tertile extremes 4.80 [95% CI: 3.31-6.97]) than in men (2.30 [1.65-3.21]). The p value for the sex interaction was 0.002. All components were more strongly associated with metabolic syndrome in women than in men, and all sex interactions were significant except for hypertension.</p> <p>Conclusions</p> <p>Our data suggest that inflammatory processes may be of particular importance in the pathogenesis of metabolic syndrome in women.</p

Paracrine cellular senescence exacerbates biliary injury and impairs regeneration

Senescence has been suggested as causing biliary cholangiopathies but how this is regulated is unclear. Here, the authors generate a mouse model of biliary senescence by deleting Mdm2 in bile ducts and show that inhibiting TGFβ limits senescence-dependent aggravation of cholangiopathies

Retrieval of Context-Associated Memory is Dependent on the Cav3.2 T-Type Calcium Channel

Among all voltage-gated calcium channels, the T-type Ca2+ channels encoded by the Cav3.2 genes are highly expressed in the hippocampus, which is associated with contextual, temporal and spatial learning and memory. However, the specific involvement of the Cav3.2 T-type Ca2+ channel in these hippocampus-dependent types of learning and memory remains unclear. To investigate the functional role of this channel in learning and memory, we subjected Cav3.2 homozygous and heterozygous knockout mice and their wild-type littermates to hippocampus-dependent behavioral tasks, including trace fear conditioning, the Morris water-maze and passive avoidance. The Cav3.2 −/− mice performed normally in the Morris water-maze and auditory trace fear conditioning tasks but were impaired in the context-cued trace fear conditioning, step-down and step-through passive avoidance tasks. Furthermore, long-term potentiation (LTP) could be induced for 180 minutes in hippocampal slices of WTs and Cav3.2 +/− mice, whereas LTP persisted for only 120 minutes in Cav3.2 −/− mice. To determine whether the hippocampal formation is responsible for the impaired behavioral phenotypes, we next performed experiments to knock down local function of the Cav3.2 T-type Ca2+ channel in the hippocampus. Wild-type mice infused with mibefradil, a T-type channel blocker, exhibited similar behaviors as homozygous knockouts. Taken together, our results demonstrate that retrieval of context-associated memory is dependent on the Cav3.2 T-type Ca2+ channel

miRNAs at the heart of the matter

Cardiovascular disease is among the main causes of morbidity and mortality in developed countries. The pathological process of the heart is associated with altered expression profile of genes that are important for cardiac function. MicroRNAs (miRNAs) have emerged as one of the central players of gene expression regulation. The implications of miRNAs in the pathological process of cardiovascular system have recently been recognized, representing the most rapidly evolving research field. Here, we summarize and analyze the currently available data from our own laboratory and other groups, providing a comprehensive overview of miRNA function in the heart, including a brief introduction of miRNA biology, expression profile of miRNAs in cardiac tissue, role of miRNAs in cardiac hypertrophy and heart failure, the arrhythmogenic potential of miRNAs, the involvement of miRNAs in vascular angiogenesis, and regulation of cardiomyocyte apoptosis by miRNAs. The target genes and signaling pathways linking the miRNAs to cardiovascular disease are highlighted. The applications of miRNA interference technologies for manipulating miRNA expression, stability, and function as new strategies for molecular therapy of human disease are evaluated. Finally, some specific issues related to future directions of the research on miRNAs relevant to cardiovascular disease are pinpointed and speculated

Transcriptome Analysis Reveals Strain-Specific and Conserved Stemness Genes in Schmidtea mediterranea

The planarian Schmidtea mediterranea is a powerful model organism for studying stem cell biology due to its extraordinary regenerative ability mediated by neoblasts, a population of adult somatic stem cells. Elucidation of the S. mediterranea transcriptome and the dynamics of transcript expression will increase our understanding of the gene regulatory programs that regulate stem cell function and differentiation. Here, we have used RNA-Seq to characterize the S. mediterranea transcriptome in sexual and asexual animals and in purified neoblast and differentiated cell populations. Our analysis identified many uncharacterized genes, transcripts, and alternatively spliced isoforms that are differentially expressed in a strain or cell type-specific manner. Transcriptome profiling of purified neoblasts and differentiated cells identified neoblast-enriched transcripts, many of which likely play important roles in regeneration and stem cell function. Strikingly, many of the neoblast-enriched genes are orthologs of genes whose expression is enriched in human embryonic stem cells, suggesting that a core set of genes that regulate stem cell function are conserved across metazoan species