949 research outputs found

    Sobolev spaces and trace theorems for time-fractional evolution equations

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    We establish trace and extension theorems for evolutionary equations with the Caputo fractional derivatives in (weighted) LpL_p spaces. To achieve this, we identify weighted Sobolev and Besov spaces with mixed norms that accommodate solution spaces and their initial values well-suited for equations involving time-fractional derivatives. Our analysis encompasses both time-fractional sub-diffusion and super-diffusion equations. We also provide observations on the initial behavior of solutions to time-fractional equations

    A Study on the Factors That Influence the Acoustic Performance of a Steel Stud Wall Assembly

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    With the recent introduction of light gauge steel framing systems in the concrete-dominated Korean construction industry, more buildings are built with drywall that is mainly composed of steel studs and gypsum boards. While load-bearing steel studs are extensively applied in residential construction, nonload-bearing steel studs are applied in various building fields such as commercial, educational, as well as residential. As building projects involving steel stud walls are becoming to increase, higher demands in performance are requested from architects and builders, especially in the field of sound performance. A series of acoustic test were performed in the nationally certified sound-testing laboratory at Korean Institute of Construction Technology (KICT) in order to evaluate and analyze factors that influence acoustic performance of steel stud wall assemblies. Factors affecting the acoustic performance of steel stud walls that are analyzed in this paper include among others, the composition and structure of steel studs, stud spacing, stud thickness, stud size, use of resilient channel, screw spacing, etc. Factors relating to gypsum boards that were tested as part of the evaluation of acoustic performance are not included in this paper. Results of this study, which is co-funded by 3 major gypsum board companies in Korea, are being used to develop stud wall assemblies that meet the required acoustic performance for unit-to-unit separating walls, as well as present architects and builders with a better understanding on the sound behavior of steel stud drywall

    Mobile Learning Initiative through SMS: A Formative Evaluation

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    Mobile technologies such as mobile phones are becoming cheaper and easy to use. Almost all learners enrolled at the Open University Malaysia (OUM) own mobile phones. In a 2008 study to determine learners’ perceptions toward mobile learning, most (82.8 percent) indicated that they could imagine themselves learning through mobile devices. Hence, in mid-2009, a mobile learning initiative via text messaging was piloted for one of OUM’s first semester courses entitled, “Learning Skills for Open and Distance Learning.” The initiative was expected to provide learners with an enhanced learning environment that will, among others, spur them to perform various learning tasks in a timely manner, feel guided on what or how to learn as well as be reminded on certain aspects of the course. In addition, some of the messages sent were designed to motivate the learners. The main objective of the mobile learning initiative was to complement the print module and the two main modes of learning: face-to-face tutorials and online discussions. To determine learners’ response to the Short Message Service (SMS) messages, a formative evaluation through focus group discussions at six learning centres in the middle of the semester. Feedback and suggestions given were considered and adjustments were made in the implementation of the initiative for the second half of the semester. (Authors' abstract

    Palladium Catalysts for Dehydrogenation of Ammonia Borane with Preferential B−H Activation

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    Cationic Pd(II) complexes catalyzed the dehydrogenation of ammonia borane in the most efficient manner with the release of 2.0 equiv of H_2 in less than 60 s at 25 °C. Most of the hydrogen atoms were obtained from the boron atom of the ammonia borane. The first step of the dehydrogenation reaction was elaborated using density functional theory calculations

    Role of interleukin-10 in endochondral bone formation in mice: Anabolic effect via the bone morphogenetic protein/Smad pathway

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    Objective: Interleukin-10 (IL-10) is a pleiotropic immunoregulatory cytokine with a chondroprotective effect that is elevated in cartilage and synovium in patients with osteoarthritis. However, the role of IL-10 during endochondral bone formation and its mechanism of action have not been elucidated. Methods: IL-10-/- mice and IL-10-treated tibial organ cultures were used to study loss and gain of IL-10 functions, respectively, during endochondral bone formation. Primary chondrocytes from the long bones of mouse embryos were cultured with and without IL-10. To assess the role of IL-10 in chondrogenic differentiation, we conducted mesenchymal cell micromass cultures. Results: The lengths of whole skeletons from IL-10-/- mice were similar to those of their wild-type littermates, although their skull diameters were smaller. The tibial growth plates of IL-10-/- mice showed shortening of the proliferating zone. Treatment with IL-10 significantly increased tibial lengths in organ culture. IL-10 also induced chondrocyte proliferation and hypertrophic differentiation in primary chondrocytes in vitro. Mechanistically, IL-10 activated STAT-3 and the Smad1/5/8 and ERK-1/2 MAP kinase pathways and induced the expression of bone morphogenetic protein 2 (BMP-2) and BMP-6 in primary chondrocytes. Furthermore, the blocking of BMP signaling attenuated the IL-10-mediated induction of cyclin D1 and RUNX-2 in primary chondrocytes and suppressed Alcian blue and alkaline phosphatase staining in mesenchymal cell micromass cultures. Conclusion: These results indicate that IL-10 acts as a stimulator of chondrocyte proliferation and chondrogenic or hypertrophic differentiation via activation of the BMP signaling pathway. © 2013, American College of Rheumatology

    (S)-[5-Methyl-3-(3-methyl­thio­phen-2-yl)-4,5-dihydro­isoxazol-5-yl]methanol

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    In the title compound, C10H13NO2S, the thio­phene and isoxazoline rings are almost coplanar, the dihedral angle between their least-squares planes being 2.08 (1)°. The O—H atoms of the methyl hy­droxy group and the N atom of the isoxazole ring are orientated in the same direction to allow for the formation of inter­molecular O—H⋯N hydrogen bonds that lead to a supra­molecular chain along the a axis

    Age-Related Changes in Antioxidative Enzyme Capacity in Tongue of Fischer 344 Rats

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    Objectives Antioxidative enzyme efficiency changes in some organs with age. However, no study has been conducted on age-related antioxidant enzyme changes in tongue. In the present study, the authors investigated the activities of four antioxidative enzymes and their protein expressions in the tongues of young and old Fischer 344 rats. Methods Age-dependent changes in the enzyme activities of total superoxide dismutase (SOD), Mn-SOD, Cu/Zn-SOD, catalase (CAT), and glutathione peroxidase (GPx) were determined using chemical kits, and the protein expressions levels of these enzymes by Western blotting. The study was conducted using rats aged 7 months (the young group, n=8) and 22 months (the old group, n=8). Results Total SOD, Cu/Zn-SOD, and GPx activities in the tongues of old rats were lower than in young rats, and similarly, corresponding protein expressions were downregulated in old rats. On the other hand, although the protein expressions of Mn-SOD and CAT were lower in old rats, their enzyme activities were not. Conclusion The results of this study provide a possible mechanism for the tongue aging process, as in old Fischer 344 rats the antioxidant defense system was diminished with respect to enzyme activity levels and protein abundances

    Improved reversibility in lithium-oxygen battery: Understanding elementary reactions and surface charge engineering of metal alloy catalyst

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    Most Li-O-2 batteries suffer from sluggish kinetics during oxygen evolution reactions (OERs). To overcome this drawback, we take the lesson from other catalysis researches that showed improved catalytic activities by employing metal alloy catalysts. Such research effort has led us to find Pt3Co nanoparticles as an effective OER catalyst in Li-O-2 batteries. The superior catalytic activity was reflected in the substantially decreased overpotentials and improved cycling/rate performance compared to those of other catalysts. Density functional theory calculations suggested that the low OER overpotentials are associated with the reduced adsorption strength of LiO2 on the outermost Pt catalytic sites. Also, the alloy catalyst generates amorphous Li2O2 conformally coated around the catalyst and thus facilitates easier decomposition and higher reversibility. This investigation conveys an important message that understanding elementary reactions and surface charge engineering of air-catalysts are one of the most effective approaches in resolving the chronic sluggish charging kinetics in Li-O-2 batteries.
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