Effect of rib spacing on heat transfer and friction in a rotating two-pass rectangular (AR=1:2) channel

The research focuses on testing the heat transfer enhancement in a channel for different spacing of the rib turbulators. Those ribs are put on the surface in the two pass rectangular channel with an aspect ratio of AR=1:2. The cross section of the rib is 1.59 x 1.59 mm. Those ribs are put on the leading and trailing walls of the channel with the angle of flow attack to the mainstream of 45ð. The rotating speed is fixed at 550-RPM with the channel orientation at ò=90ð. Air is used as the coolant through the cooling passage with the coolant-to-wall density ratio ( ààâ ) maintained around 0.115 in the first pass and 0.08 in the second pass. The Reynolds numbers are controlled at 5000, 10000, 25000, and 40000. The rib spacing-to-height ratios (P/e) are 3, 5, 7.5, and 10. The heat transfer coefficient and friction factor are measured to determine the effect of the different rib distributions. Stationary cases and rotational cases are examined and compared. The result shows that the highest thermal performance is P/e=5 for the stationary case and P/e=7.5 for the rotating case

Heat transfer in leading and trailing edge cooling channels of the gas turbine blade under high rotation numbers

The gas turbine blade/vane internal cooling is achieved by circulating the compressed air through the cooling passages inside the turbine blade. Leading edge and trailing edge of the turbine blade are two critical regions which need to be properly cooled. Leading edge region receives extremely hot mainstream flow and high heat transfer enhancement is required. Trailing edge region usually has narrow shaped geometry and applicable cooling techniques are restricted. Heat transfer will be investigated in the leading edge and trailing edge cooling channels at high rotation numbers close to the engine condition. Heat transfer and pressure drop has been investigated in an equilateral triangular channel (Dh=1.83cm) to simulate the cooling channel near the leading edge of the gas turbine blade. Three different rib configurations (45°, inverted 45°, and 90°) were tested at four different Reynolds numbers (10000-40000), each with five different rotational speeds (0-400 rpm). By varying the Reynolds numbers (10000-40000) and the rotational speeds (0-400 rpm), the rotation number and buoyancy parameter reached in this study were 0-0.58 and 0-2.3, respectively. 45° angled ribs show the highest thermal performance at stationary condition. 90° ribs have the highest thermal performance at the highest rotation number of 0.58. Heat transfer coefficients are also experimentally measured in a wedge-shaped cooling channel (Dh =2.22cm, Ac=7.62cm2) to model an internal cooling passage near the trailing edge of a gas turbine blade where the coolant discharges through the slot to the mainstream flow. Tapered ribs are put on the leading and trailing surfaces with an angle of attack of 45°. The ribs are parallel with staggered arrangement on opposite walls. The inlet Reynolds number of the coolant varies from 10,000 to 40,000 and the rotational speeds varies from 0 to 500 rpm. The inlet rotation number is from 0 - 1.0. The local rotation number and buoyancy parameter are determined by the rotational speeds and the local Reynolds number at each region. Results show that heat transfer is high near the regions where strong slot ejection exists. Both the rotation number and buoyancy parameter have been correlated to predict the rotational heat transfer enhancement

FASTSNP: an always up-to-date and extendable service for SNP function analysis and prioritization

Single nucleotide polymorphism (SNP) prioritization based on the phenotypic risk is essential for association studies. Assessment of the risk requires access to a variety of heterogeneous biological databases and analytical tools. FASTSNP (function analysis and selection tool for single nucleotide polymorphisms) is a web server that allows users to efficiently identify and prioritize high-risk SNPs according to their phenotypic risks and putative functional effects. A unique feature of FASTSNP is that the functional effect information used for SNP prioritization is always up-to-date, because FASTSNP extracts the information from 11 external web servers at query time using a team of web wrapper agents. Moreover, FASTSNP is extendable by simply deploying more Web wrapper agents. To validate the results of our prioritization, we analyzed 1569 SNPs from the SNP500Cancer database. The results show that SNPs with a high predicted risk exhibit low allele frequencies for the minor alleles, consistent with a well-known finding that a strong selective pressure exists for functional polymorphisms. We have been using FASTSNP for 2 years and FASTSNP enables us to discover a novel promoter polymorphism. FASTSNP is available at

On-Call Duty Effects on Sleep-State Physiological Stability in Male Medical Interns

Background: On-call duty among medical interns is characterized by sleep deprivation and stressful working conditions, both of which alter cardiac autonomic modulation. We hypothesized that sleep stability decreased in medical interns during on-call duty. We used cardiopulmonary-coupling (CPC) analysis to test our hypothesis. Methods: We used electrocardiogram (ECG)-based CPC analysis to quantify physiological parameters of sleep stability in 13 medical interns during on-call and on-call duty-free periods. There were ten 33.5-h on-call duty shifts per month for interns, each followed by 2 on-call duty-free days, over 3 months. Measurements during sleep were collected before, during, and after an on-call shift. Measurements were repeated 3 months later during an on-call duty-free period. Results: The medical interns had significantly reduced stable sleep, and displayed increased latency to the first epoch of stable sleep during the on-call night shift, compared to the pre-call and on-call duty-free nights. Interns also had significantly increased rapid-eye-movement (REM) sleep during the on-call night shift, compared to the pre-call and on-call duty-free nights. Conclusion: Medical interns suffer disrupted sleep stability and continuity during on-call night shifts. The ECG-based CPC analysis provides a straightforward means to quantify sleep quality and stability in medical staff performing shift work under stressful conditions

Long-Range Transport of Asian Dust and Air Pollutants to Taiwan

Dust storms and long-range transport of pollutants are major environ-mental concerns of Taiwan during the winter monsoon season when north-easterly winds prevail following passages of cold fronts. To quantify the impact on air quality, we develop an objective method to classify and study the long-range transport processes by examining the frontal passages in two representative years. We have found that there is about one frontal passage per week in winter and spring, consistent with the climatological average. The long-range transport events are classified into three types ac-cording to their degrees of impact on levels of dusts and air pollutants in Taiwan, namely dust storms (DS), long-range transport with pollutants (FP), and long-range transport of background air masses (BG). DS cases occurred 4.7 % of the time over 14 months and had a large average PM10 concentra-tion of 127.6 µg m 3 − at Wan-Li station. FP cases occurred 1.9 % of the time and the mean concentration of PM10 during the FP periods was about 85 µg m 3 −. BG cases happened 18.6 % of the time and the mean concentra-tion of PM10 was 32.8 µg m 3−. Dust storms and air pollutants tend to be transported in different air parcels as evidenced by a lack of correlation between dust aerosols and air pollutants. The frequency of local pollution (LP) cases was 71.7 % in winter and spring. The average PM10 concentra-tion of LP cases at the Wan-Li station was 47.4 µg m 3 −. However, about one to two-thirds of the PM10 during LP cases can be attributed to the long

Andrographis paniculata

Andrographolide is the most abundant terpenoid of A. paniculata which is used in the treatment of diabetes. In this study, we investigated the effects of A. paniculata extract (APE) and andrographolide on the expression of drug-metabolizing enzymes in rat liver and determined whether modulation of these enzymes changed the pharmacokinetics of tolbutamide. Rats were intragastrically dosed with 2 g/kg/day APE or 50 mg/kg/day andrographolide for 5 days before a dose of 20 mg/kg tolbutamide was given. APE and andrographolide reduced the AUC0–12 h of tolbutamide by 37% and 18%, respectively, compared with that in controls. The protein and mRNA levels and enzyme activities of CYP2C6/11, CYP1A1/2, and CYP3A1/2 were increased by APE and andrographolide. To evaluate whether APE or andrographolide affected the hypoglycemic action of tolbutamide, high-fat diet-induced obese mice were used and treated in the same manner as the rats. APE and andrographolide increased CYP2C6/11 expression and decreased plasma tolbutamide levels. In a glucose tolerance test, however, the hypoglycemic effect of tolbutamide was not changed by APE or andrographolide. These results suggest that APE and andrographolide accelerate the metabolism rate of tolbutamide through increased expression and activity of drug-metabolizing enzymes. APE and andrographolide, however, do not impair the hypoglycemic effect of tolbutamide

ALMA Survey of Orion Planck Galactic Cold Clumps (ALMASOP) : A Hot Corino Survey toward Protostellar Cores in the Orion Cloud

The presence of complex organic molecules (COMs) in the interstellar medium is of great interest since it may link to the origin and prevalence of life in the universe. Aiming to investigate the occurrence of COMs and their possible origins, we conducted a chemical census toward a sample of protostellar cores as part of the Atacama Large Millimeter/submillimeter Array Survey of Orion Planck Galactic Cold Clumps project. We report the detection of 11 hot corino sources, which exhibit compact emissions from warm and abundant COMs, among 56 Class 0/I protostellar cores. All of the hot corino sources discovered are likely Class 0, and their sizes of the warm region (>100 K) are comparable to 100 au. The luminosity of the hot corino sources exhibits positive correlations with the total number of methanol and the extent of its emissions. Such correlations are consistent with the thermal desorption picture for the presence of hot corinos and suggest that the lower-luminosity (Class 0) sources likely have a smaller region with COM emissions. With the same sample selection method and detection criteria being applied, the detection rates of the warm methanol in the Orion cloud (15/37) and the Perseus cloud (28/50) are statistically similar when the cloud distances and the limited sample size are considered. Observing the same set of COM transitions will bring a more informative comparison between the cloud properties.Peer reviewe

ALMA Survey of Orion Planck Galactic Cold Clumps (ALMASOP). I. Detection of New Hot Corinos with the ACA

We report the detection of four new hot corino sources, G211.47-19.27S, G208.68-19.20N1, G210.49-19.79W, and G192.12-11.10, from a survey study of Planck Galactic Cold Clumps in the Orion Molecular Cloud Complex with the Atacama Compact Array. Three sources had been identified as low-mass Class 0 protostars in the Herschel Orion Protostar Survey. One source in the lambda Orionis region is first reported as a protostellar core. We have observed abundant complex organic molecules (COMs), primarily methanol but also other oxygen-bearing COMs (in G211.47-19.27S and G208.68-19.20N1) and the molecule of prebiotic interest NH2CHO (in G211.47-19.27S), signifying the presence of hot corinos. While our spatial resolution is not sufficient to resolve most of the molecular emission structure, the large line width and high rotational temperature of COMs suggest that they likely reside in the hotter and innermost region immediately surrounding the protostar. In G211.47-19.27S, the D/H ratio of methanol ([CH2DOH]/[CH3OH]) and the(12)C/C-13 ratio of methanol ([CH3OH]/[(CH3OH)-C-13]) are comparable to those of other hot corinos. Hydrocarbons and long-carbon-chain molecules such as c-C(3)H(2)and HCCCN are also detected in the four sources, likely tracing the outer and cooler molecular envelopes.Peer reviewe

SirT1—A Sensor for Monitoring Self-Renewal and Aging Process in Retinal Stem Cells

Retinal stem cells bear potency of proliferation, self-renewal, and differentiation into many retinal cells. Utilizing appropriate sensors one can effectively detect the self-renewal and aging process abilities. Silencing information regulator (SirT1), a member of the sirtuin family, is a NAD-dependent histone deacetylase and an essential mediator for longevity in normal cells by calorie restriction. We firstly investigate the SirT1 mRNA expression in retinal stem cells from rats and 19 human eyes of different ages. Results revealed that SirT1 expression was significantly decreased in in vivo aged eyes, associated with poor self-renewal abilities. Additionally, SirT1 mRNA levels were dose-dependently increased in resveratrol- treated retinal stem cells. The expression of SirT1 on oxidative stress-induced damage was significantly decreased, negatively correlated with the level of intracellular reactive oxygen species production. Treatment with resveratrol could effectively further reduce oxidative stress induced by H2O2 treatment in retinal stem cells. Importantly, the anti-oxidant effects of resveratrol in H2O2-treated retinal stem cells were significantly abolished by knockdown of SirT1 expression (sh-SirT1). SirT1 expression provides a feasible sensor in assessing self-renewal and aging process in retinal stem cells. Resveratrol can prevent reactive oxygen species-induced damages via increased retinal SirT1 expression