Biological actions and molecular effects of resveratrol, pterostilbene, and 3′-hydroxypterostilbene

AbstractStilbenes are a class of polyphenolic compounds, naturally found in a wide variety of dietary sources such as grapes, berries, peanuts, red wine, and some medicinal plants. There are several well-known stilbenes including trans-resveratrol, pterostilbene, and 3′-hydroxypterostilbene. The core chemical structure of stilbene compounds is 1,2-diphenylethylene. Recently, stilbenes have attracted extensive attention and interest due to their wide range of health-beneficial effects such as anti-inflammation, -carcinogenic, -diabetes, and -dyslipidemia activities. Moreover, accumulating in vitro and in vivo studies have reported that stilbene compounds act as inducers of multiple cell-death pathways such as apoptosis, cell cycle arrest, and autophagy for chemopreventive and chemotherapeutic agents in several types of cancer cells. The aim of this review is to highlight recent molecular findings and biological actions of trans-resveratrol, pterostilbene, and 3′-hydroxypterostilbene

Relationships between Connectedness, Performance Proficiency, Satisfaction, and Online Learning Continuance

Maintaining momentum is vital in terms of how soon students can complete a program, especially for those who are in the early stage of taking online courses. This study attempted to extend the existing literature by examining the influence of online students’ perceived sense of connectedness, performance proficiency, and satisfaction on their intentions to continue an online learning course. A quantitative survey approach was adopted to test our hypothesized structural model. Three hundred and sixty-nine students who had taken fewer than three fully online courses participated in this study. The results revealed that three out of four testing hypotheses were all supported at the 0.01 significance level, and one of the path coefficients indicated that online students’ confidence in their ability or competency to perform academic tasks did not directly influence their intention to take future online courses. Instead, the influence of performance proficiency on online learning continuance intention was mediated through the factor of satisfaction. In addition, satisfaction was found to have a significantly direct impact on online learning continuance intention, suggesting that when students taking online courses are satisfied with their online learning experience, the likelihood for them to continue taking other online courses is higher

Prevalence of Tidal Interactions among Local Seyfert Galaxies

No mechanisms have hitherto been conclusively demonstrated to be responsible for initiating optically-luminous nuclear (Seyfert) activity in local disk galaxies. Only a small minority of such galaxies are visibly disturbed in optical starlight, with the observed disturbances being at best marginally stronger than those found in matched samples of inactive galaxies. Here, we report the first systematic study of an optically-selected sample of twenty-three active galaxies in atomic hydrogen (HI) gas, which is the most sensitive and enduring tracer known of tidal interactions. Eighteen of these galaxies are (generally) classified as Seyferts, with over half (and perhaps all) having [OIII] luminosities within two orders of magnitude of Quasi-Stellar Objects. Only ~28% of these Seyfert galaxies are visibly disturbed in optical DSS2 images. By contrast, ~94% of the same galaxies are disturbed in HI, in nearly all cases not just spatially but also kinematically on galactic (>~20 kpc) scales. In at least ~67% and perhaps up to ~94% of cases, the observed HI disturbances can be traced to tidal interactions with neighboring galaxies detected also in HI. The majority of these neighboring galaxies have projected separations of <~ 100 kpc and differ in radial velocities by <~100 km/s from their respective Seyfert galaxies, and many have optical luminosities ranging from the Small to Large Magellanic Clouds. In a companion paper, we show that only ~15% of a matched control sample of inactive galaxies display comparable HI disturbances. Our results suggest that: i) most Seyfert galaxies (with high nuclear luminosities) have experienced tidal interactions in the recent past; ii) in most cases, these tidal interactions are responsible for initiating events that lead to their nuclear activity.Comment: 64 pages, 44 figures, accepted for publication in ApJ. Changes: Nothing is changed except that the paper was compiled differently to reduce the number of pages. To be friendly to the Earth forest, you could also choose to only print the text part of the paper and view images on line. (see http://www.astro.virginia.edu/~ck2v/paper/

Prevalence of Tidal Interactions among Local Seyfert Galaxies: The Control Experiment

We test whether there is a relation between the observed tidal interactions and Seyfert activity by imaging in HI twenty inactive galaxies at the same spatial resolution and detection threshold as the Seyfert sample. This control sample of inactive galaxies were closely matched in Hubble type, range in size and inclination, and have roughly comparable galaxy optical luminosity to the Seyfert galaxies. We find that only ~15% of the galaxies in our control sample are disturbed in HI, whereas the remaining ~85% show no disturbances whatsoever in HI. Even at a spatial resolution of ~10 kpc, none of the latter galaxies show appreciable HI disturbances reminiscent of tidal features. In a companion paper (Kuo et al. 2008), we report results from the first systematic imaging survey of Seyfert galaxies in atomic hydrogen (HI) gas. We find that only ~28% of the eighteen Seyfert galaxies in that sample are visibly disturbed in optical starlight. By contrast, ~94% of the same Seyfert galaxies are disturbed spatially and usually also kinematically in HI gas on galactic scales of >~20 kpc. In at least ~67% and up to perhaps ~94% of cases, the observed disturbances can be traced to tidal interactions with neighboring galaxies detected also in HI. The dramatic contrast between the observed prevalence of HI disturbances in the Seyfert and control samples implicates tidal interactions in initiating events that lead to luminous Seyfert activity in a large fraction of local disk galaxies.Comment: 38 pages, 27 figures, Accepted for publication in ApJ. Changes from previous version: The title of the previous version of this paper appeared in Astroph was incorrect. It has been replaced with the correct on

High-Frequency Ultrasound Imaging to Evaluate Liver Fibrosis Progression in Rats and Yi Guan Jian Herbal Therapeutic Effects

The animals used in liver fibrosis studies must usually be sacrificed. Ultrasound has been demonstrated to have the ability to diagnose hepatic fibrosis and cirrhosis in experimental small-animal models. However, few studies have used high-frequency ultrasound (HFU, 40 MHz) to monitor changes in the rat liver and other hollow organs longitudinally. In this study, liver fibrosis was induced by administering dimethylnitrosamine (DMN) in SD rats, aged 8 weeks, for three consecutive days per week for up to 4 weeks. A Chinese herbal medicine Yi Guan Jian (YGJ) was orally administered (1.8 g/kg daily) to DMN-induced liver fibrosis rats for 2 weeks. Compared with the normal control rats, rats treated with DMN for either 2 weeks or 4 weeks had significantly lower body weights, liver indexes and elevation of hydroxyproline, GOT, and GPT contents. YGJ herbal treatment remarkably prevented rats from DMN-induced liver fibrosis. The HFU scoring results among the normal controls, 2-week DMN-treated rats, 4-week DMN-treated rats, and combined 2-week YGJ therapy with 4-week DMN-treated rats also reached statistical significance. Thus, HFU is an accurate tool for the longitudinal analysis of liver fibrosis progression in small-animal models, and the YGJ may be useful in reversing the development of hepatic fibrosis

Relationships between Connectedness, Performance Proficiency, Satisfaction, and Online Learning Continuance

Maintaining momentum is vital in terms of how soon students can complete a program, especially for those who are in the early stage of taking online courses. This study attempted to extend the existing literature by examining the influence of online students’ perceived sense of connectedness, performance proficiency, and satisfaction on their intentions to continue an online learning course. A quantitative survey approach was adopted to test our hypothesized structural model. Three hundred and sixty-nine students who had taken fewer than three fully online courses participated in this study. The results revealed that three out of four testing hypotheses were all supported at the 0.01 significance level, and one of the path coefficients indicated that online students’ confidence in their ability or competency to perform academic tasks did not directly influence their intention to take future online courses. Instead, the influence of performance proficiency on online learning continuance intention was mediated through the factor of satisfaction. In addition, satisfaction was found to have a significantly direct impact on online learning continuance intention, suggesting that when students taking online courses are satisfied with their online learning experience, the likelihood for them to continue taking other online courses is higher.

Morphology and melt rheology of nylon 11/clay nanocomposites

Nylon 11 (PA11)/clay nanocomposites have been prepared by melt-blending, followed by melt-extrusion through a capillary. Transmission electron microscopy shows that the exfoliated clay morphology is dominant for low nanofiller content, while the intercalated one is prevailing for high filler loading. Melt rheological properties of PA11 nanocomposites have been studied in both linear and nonlinear viscoelastic response regions. In the linear regime, the nanocomposites exhibit much higher storage modulus (G') and loss modulus (G'') values than neat PA11. The values of G' and G'' increase steadily with clay loading at low concentrations, while the G' and G'' for the sample with 5 wt % clay show an inverse dependence and lie between the modulus values of the samples with 1 and 2 wt % of clay. This is attributed to the alignment/orientation of nanoclay platelets in the intercalated nanocomposite induced by capillary extrusion. In the nonlinear regime, the nanocomposites show increased shear viscosities when compared with the neat resin. The dependence of the shear viscosity on clay loading has analogous trend to that of G' and G''. Finally, a comparison has been made between the complex and steady viscosities to verify the applicability of the empirical Cox-Merz rule

The Hot and Clumpy Molecular Cocoon Surrounding the Ultracompact HII Region G5.89-0.39

We present observations of CH3CN (12-11) emission at a resolution of 2" toward the shell-like ultracompact HII region G5.89-0.39 with the Submillimeter Array. The integrated CH3CN emission reveals dense and hot molecular cocoon in the periphery of the HII region G5.89-0.39, with a CH3CN deficient region roughly centered at G5.89-0.39. By analyzing the CH3CN emission using population diagram analysis, we find, for the first time, a decreasing temperature structure from 150 to 40 K with the projected distance from Feldt's star, which is thought to be responsible for powering the HII region. Our results further indicate that the majority of the heating energy in the observed dense gas is supplied by the Feldt's star. From the derived CH3CN column density profile, we conclude that the dense gas is not uniformly-distributed but centrally-concentrated, with a power-law exponent of 5.5 for r < 8000 AU, and 2.0 for 8000 AU < r < 20000 AU, where r is the distance to Feldt's star. The estimated large power index of 5.5 can be attributed to an enhancement of CH3CN abundance in the close vicinity of Feldt's star.Comment: accepted for publication in The Astrophysical Journal Letter

An Algorithm for Cold Patch Detection in the Sea off Northeast Taiwan Using Multi-Sensor Data

Multi-sensor data from different satellites are used to identify an upwelling area in the sea off northeast Taiwan. Sea surface temperature (SST) data derived from infrared and microwave, as well as sea surface height anomaly (SSHA) data derived from satellite altimeters are used for this study. An integration filtering algorithm based on SST data is developed for detecting the cold patch induced by the upwelling. The center of the cold patch is identified by the maximum negative deviation relative to the spatial mean of a SST image within the study area and its climatological mean of each pixel. The boundary of the cold patch is found by the largest SST gradient. The along track SSHA data derived from satellite altimeters are then used to verify the detected cold patch. Applying the detecting algorithm, spatial and temporal characteristics and variations of the cold patch are revealed. The cold patch has an average area of 1.92 × 104 km2. Its occurrence frequencies are high from June to October and reach a peak in July. The mean SST of the cold patch is 23.8 °C. In addition to the annual and the intraseasonal fluctuation with main peak centered at 60 days, the cold patch also has a variation period of about 4.7 years in the interannual timescale. This implies that the Kuroshio variations and long-term and large scale processes playing roles in modifying the cold patch occurrence frequency