Experimental Studies of Low-field Landau Quantization in Two-dimensional Electron Systems in GaAs/AlGaAs Heterostructures

By applying a magnetic field perpendicular to GaAs/AlGaAs two-dimensional electron systems, we study the low-field Landau quantization when the thermal damping is reduced with decreasing the temperature. Magneto-oscillations following Shubnikov-de Haas (SdH) formula are observed even when their amplitudes are so large that the deviation to such a formula is expected. Our experimental results show the importance of the positive magneto-resistance to the extension of SdH formula under the damping induced by the disorder.Comment: 9 pages, 3 figure

From insulator to quantum Hall liquid at low magnetic fields

We have performed low-temperature transport measurements on a GaAs two-dimensional electron system at low magnetic fields. Multiple temperature-independent points and accompanying oscillations are observed in the longitudinal resistivity between the low-field insulator and the quantum Hall (QH) liquid. Our results support the existence of an intermediate regime, where the amplitudes of magneto-oscillations can be well described by conventional Shubnikov-de Haas theory, between the low-field insulator and QH liquid.Comment: Magneto-oscillations governed by Shubnikov-de Haas theory are observed between the low-field insulator and quantum Hall liqui

Effect of Substrate Temperature on the Thermoelectric Properties of the Sb 2

The antimony-telluride (Sb2Te3) thermoelectric thin films were prepared on SiO2/Si substrates by thermal evaporation method. The substrate temperature that ranged from room temperature to 150°C was adopted to deposit the Sb2Te3 thin films. The effects of substrate temperature on the microstructures and thermoelectric properties of the Sb2Te3 thin films were investigated. The crystal structure and surface morphology of the Sb2Te3 thin films were characterized by X-ray diffraction analyses and field emission scanning electron microscope observation. The RT-deposited Sb2Te3 thin films showed the amorphous phase. Te and Sb2Te3 phases were coexisted in the Sb2Te3-based thin films as the substrate temperature was higher than room temperature. The average grain sizes of the Sb2Te3-based thin films were 39 nm, 45 nm, 62 nm, 84 nm, and 108 nm, as the substrate temperatures were 50°C, 75°C, 100°C, 125°C, and 150°C, respectively. The Seebeck coefficients, electrical conductivity, and power factor were measured at room temperature; we had found that they were critically dependent on the substrate temperature

Gender-Differential Associations between Attention Deficit and Hyperactivity Symptoms and Youth Health Risk Behaviors

Attention deficit and hyperactivity disorder (ADHD) is one of the common developmental disorders that generally receives clinical attention at learning ages, and some symptoms may persist in young adulthood.1 Past research has demonstrated a consistent association between ADHD and youth health risk behaviors (e.g., cigarette smoking), which often develop during adolescence and contribute to early morbidity and mortality among young adults.2 However, ADHD symptoms are not routinely screened in adolescents and emerging adults during their visits to healthcare providers.3 The six-item Adult Self-Report Scale (ASRS-6) for ADHD has been validated in the young population for screening purposes.4 This short form is time-saving and also provides a comparable predictivity of ADHD diagnosis as that of the original long version.5 Although accumulating evidence has demonstrated the association between ADHD symptoms and youth health risk behaviors, this issue has scarcely been explored in the Taiwanese youth population.6 Therefore, this study was conducted to validate the psychometric property of the Chinese version of ASRS-6 and examine the gender-stratified association between ADHD symptoms and youth health risk behaviors

The Impact of Climate Change on Rainfall Frequency in Taiwan

The purpose of this research is to assess climate change impacts on rainfall frequency in Taiwan. The changes in future precipitation were projected statistically from general circulation model (GCM) outputs. Based on five downscaled GCM outputs [China’s FGOALS-g1.0, Japan’s CGCM2.3.2, the USA’s CM2.0, Canada’s CGCM3(T47), and France’s CM3] under the SRES A1B scenario, the frequency of the maximum consecutive dry days and maximum 1-, 2-, and 3-day rainfall during 2080 - 2099 are evaluated and compared with those in the period of 1980 - 1999. The results show that by the end of the 21st century, the risk of droughts and floods over Taiwan has a tendency to increase. The distribution of water resources in Taiwan will be more uneven, with a noticeable change in the ratio of wet and dry seasons. Due to these climate change impacts, future water conservation work will be a major challenge for governments

AMG 837: A Novel GPR40/FFA1 Agonist that Enhances Insulin Secretion and Lowers Glucose Levels in Rodents

Agonists of GPR40 (FFA1) have been proposed as a means to treat type 2 diabetes. Through lead optimization of a high throughput screening hit, we have identified a novel GPR40 agonist called AMG 837. The objective of these studies was to understand the preclinical pharmacological properties of AMG 837. The activity of AMG 837 on GPR40 was characterized through GTPγS binding, inositol phosphate accumulation and Ca2+ flux assays. Activity of AMG 837 on insulin release was assessed on isolated primary mouse islets. To determine the anti-diabetic activity of AMG 837 in vivo, we tested AMG 837 using a glucose tolerance test in normal Sprague-Dawley rats and obese Zucker fatty rats. AMG 837 was a potent partial agonist in the calcium flux assay on the GPR40 receptor and potentiated glucose stimulated insulin secretion in vitro and in vivo. Acute administration of AMG 837 lowered glucose excursions and increased glucose stimulated insulin secretion during glucose tolerance tests in both normal and Zucker fatty rats. The improvement in glucose excursions persisted following daily dosing of AMG 837 for 21-days in Zucker fatty rats. Preclinical studies demonstrated that AMG 837 was a potent GPR40 partial agonist which lowered post-prandial glucose levels. These studies support the potential utility of AMG 837 for the treatment of type 2 diabetes

Excavatoids O and P, New 12-Hydroxybriaranes from the Octocoral Briareum excavatum

Two new 12-hydroxybriarane diterpenoids, designated as excavatoids O (1) and P (2), were isolated from the octocoral Briareum excavatum. The structures of briaranes 1 and 2 were established on the basis of extensive spectral data analysis. Excavatoid P (2) is the first metabolite which possesses a 6β -chlorine atom in briarane analogues

Characterizing informative sequence descriptors and predicting binding affinities of heterodimeric protein complexes

BACKGROUND: Protein-protein interactions (PPIs) are involved in various biological processes, and underlying mechanism of the interactions plays a crucial role in therapeutics and protein engineering. Most machine learning approaches have been developed for predicting the binding affinity of protein-protein complexes based on structure and functional information. This work aims to predict the binding affinity of heterodimeric protein complexes from sequences only. RESULTS: This work proposes a support vector machine (SVM) based binding affinity classifier, called SVM-BAC, to classify heterodimeric protein complexes based on the prediction of their binding affinity. SVM-BAC identified 14 of 580 sequence descriptors (physicochemical, energetic and conformational properties of the 20 amino acids) to classify 216 heterodimeric protein complexes into low and high binding affinity. SVM-BAC yielded the training accuracy, sensitivity, specificity, AUC and test accuracy of 85.80%, 0.89, 0.83, 0.86 and 83.33%, respectively, better than existing machine learning algorithms. The 14 features and support vector regression were further used to estimate the binding affinities (Pkd) of 200 heterodimeric protein complexes. Prediction performance of a Jackknife test was the correlation coefficient of 0.34 and mean absolute error of 1.4. We further analyze three informative physicochemical properties according to their contribution to prediction performance. Results reveal that the following properties are effective in predicting the binding affinity of heterodimeric protein complexes: apparent partition energy based on buried molar fractions, relations between chemical structure and biological activity in principal component analysis IV, and normalized frequency of beta turn. CONCLUSIONS: The proposed sequence-based prediction method SVM-BAC uses an optimal feature selection method to identify 14 informative features to classify and predict binding affinity of heterodimeric protein complexes. The characterization analysis revealed that the average numbers of beta turns and hydrogen bonds at protein-protein interfaces in high binding affinity complexes are more than those in low binding affinity complexes

Terpenoids from the Octocorals Menella sp. (Plexauridae) and Lobophytum crassum (Alcyonacea)

A new germacrane-type sesquiterpenoid, menelloide E (1), and a new cembrane-type diterpenoid, lobocrassin F (2), were isolated from the octocorals Menella sp. and Lobophytum crassum, respectively. The structures of terpenoids 1 and 2 were determined by spectroscopic and chemical methods and compound 2 was found to display a significant inhibitory effect on the release of elastase by human neutrophils

Clinical impact of pharmacogenetic risk variants in a large chinese cohort.

Incorporating pharmacogenetics into clinical practice promises to improve therapeutic outcomes by optimizing drug selection and dosage based on genetic factors affecting drug response. A key advantage of PGx-guided therapy is to decrease the likelihood of adverse events. To evaluate the clinical impact of PGx risk variants, we performed a retrospective study using genetic and clinical data from the largest Han Chinese cohort, comprising 486,956 individuals, assembled by the Taiwan Precision Medicine Initiative. We found that nearly all participants carried at least one genetic variant that could affect drug response, with many carrying multiple risk variants. Here we show the detailed analyses of four gene-drug pairs, azathioprine (NUDT15/TPMT), clopidogrel (CYP2C19), statins (ABCG2/CYP2C9/SLCO1B1), and NSAIDs (CYP2C9), for which sufficient data exists for statistical power. While the results validate previous findings that PGx risk variants are significantly associated with drug-related adverse events or ineffectiveness, the excess risk of adverse events or lack of efficacy is small compared to that found in those without the PGx risk variants, and most patients with PGx variants do not suffer from adverse events. Our results point to the complexity of implementing PGx in clinical practice and the need for integrative approaches to optimize precision medicine