Far-infrared absorption in parallel quantum wires with weak tunneling

We study collective and single-particle intersubband excitations in a system of quantum wires coupled via weak tunneling. For an isolated wire with parabolic confinement, the Kohn's theorem guarantees that the absorption spectrum represents a single sharp peak centered at the frequency given by the bare confining potential. We show that the effect of weak tunneling between two parabolic quantum wires is twofold: (i) additional peaks corresponding to single-particle excitations appear in the absorption spectrum, and (ii) the main absorption peak acquires a depolarization shift. We also show that the interplay between tunneling and weak perpendicular magnetic field drastically enhances the dispersion of single-particle excitations. The latter leads to a strong damping of the intersubband plasmon for magnetic fields exceeding a critical value.Comment: 18 pages + 6 postcript figure

A SYNTHESIS OF SOLID ACID CATALYSTS FOR USING IN HYDROLYSIS OF CELLULOSE FROM RICE STRAW INTO GLUCOSE

In this study, a carbon–based solid acid catalyst was prepared via hydrothermal carbonization method (HTC) using glucose and pyrolysed waste tyre as carbon precursors and aqueous solution of H2SO4 as sulfonation agent. Prepared catalysts were characterized by X–ray diffraction (XRD), scanning electron microscope (SEM), Fourier transform infrared FT–IR and Brunauer–Emmett–Teller (BET). As the result, catalysts were manufactured with the appropriate physical and chemical characteristics and high acidity

Situated learning theory and incubatee performance at the DOST technology business incubator program: Is entrepreneurial learning and development a mediator?

Incubatee startup founders asks for solutions and ideas whenever they encountered business problems in their startups enrolled in a Technology Business Incubator program. It is argued that situated learning may help these incubatees find solutions to their problems via interaction with co-incubatees. Some incubatees who have previous working experience do have a certain level of entrepreneurial learning that contributes to their performance. To test, 58 incubatees were surveyed on the mediating effect of entrepreneurial learning and development on the hypothesized situated learning – incubate performance nexus. Incubator managers from different TBIs were invited to cross validate the survey results through written narratives. Mediation analysis disclosed that situated learning and entrepreneurial learning and development significantly affected incubatee performance although both variables are poor predictors if taken altogether. Entrepreneurial learning and development attained by the incubatees does not mediate the link between situated learning and incubatee performance. Insights from the written narratives of the interviewees have corroborated with the results. Recommendation given from the study is to pursue a study using other frameworks in order to understand further what may play a critical role in incubatee performance

Effect of different drying methods on the protein and product quality of hairtail fish meat gel

Three different methods, namely hot air drying (HA), microwave vacuum drying (MV), and vacuum freeze drying (FD), were employed to investigate the effect of drying method on the quality of hairtail fish meat gel. Compared with HA and MV, FD samples showed a better quality in terms of moisture content, water absorption index, and water solubility index, and had the highest overall acceptance in sensory evaluation. FD preserved the protein from degradation and formed an ordered porous microstructure. The nitrogen fraction assay revealed that protein was degraded into 40–100 kDa fragments during drying in HA, which was almost not affected by MV and FD. Overall, FD was the most suitable method for drying of meat gel made from hairtail, followed by MV and HA

The Src Homology 2 and Phosphotyrosine Binding Domains of the ShcC Adaptor Protein Function as Inhibitors of Mitogenic Signaling by the Epidermal Growth Factor Receptor

Upon ligand activation, the epidermal growth factor receptor (EGFR) becomes tyrosine-phosphorylated, thereby recruiting intracellular signaling proteins such as Shc. EGFR binding of Shc proteins results in their tyrosine phosphorylation and subsequent activation of the Ras and Erk pathways. Shc interaction with activated receptor tyrosine kinases is mediated by two distinct phosphotyrosine interaction domains, an NH2-terminal phosphotyrosine binding (PTB) domain and a COOH-terminal Src homology 2 (SH2) domain. The relative importance of these two domains for EGFR binding was examined by determining if expression of the isolated SH2 or PTB domain of ShcC would inhibit EGFR signaling. The SH2 domain potently inhibited numerous aspects of EGFR signaling including activation of Erk2 and the Elk-1 transcription factor as well as EGFR-dependent transformation. Furthermore, the SH2 domain inhibited focus formation by the Neu oncoprotein, another EGFR family member. Surprisingly, inhibition of the EGFR by the SH2 domain did not involve stable association with the receptor. In contrast, the PTB domain associated quite well with the receptor yet had little effect on EGFR signaling. Although the EGFR cytoplasmic tail contains consensus binding sites for the PTB and SH2 domains of ShcC, and both domains of ShcC interact with the receptor in vitro, the SH2 domain is more potent for inhibiting receptor function in vivo. However, inhibition is not due to stable association with the receptor, suggesting that the SH2 domain is binding to a heretofore unknown protein(s) necessary for proper EGFR function