Bandstructure of Interdiffused InGaN/GaN Quantum Well

Quantum well composition intermixing is a thermal induced interdiffusion of the constituent atoms through the hetero- interface. The intermixed structures created by both impurity induced and impurity-free vacancy promoted processes have recently attracted high attention. In recent years, blue green LED and laser of III-nitride semiconductors have attracted a large amount of interest. This is mainly due to its large bandgap range from 1.89eV to 3.44eV. InGaN/GaN single quantum well structures have been used to achieve high lumens blue and green light emitting diodes. In this paper, we will present the band structure of strained InGaN/GaN single quantum well under the influence of interdiffusion. Band structure is a fundamental aspect in determining the electronic and optical properties of the materials such as optical gain, refractive index, absorption, etc.published_or_final_versio

pH dependence of sorption of Cd2+, Zn2+, Cu2+ and Cr3+ on crude water and sodium chloride extracts of Moringa stenopetala and Moringa oleifera,/i>

The ability of crude water and sodium chloride extracts of partially defatted powder of Moringa stenopetala (MS) and Moringa oleifera (MO) to remove heavy metals (Cd2+, Zn2+, Cu2+ and Cr3+) fromsingle ion solution was investigated. At initial metal concentration of about 4 ppm, the extracts showed complete sorption for Cd2+, Zn2+ and Cr3+ ions at pH above 7.8, 4.0 and 4.0, respectively, at a dose of 1.0 ml of sorbent in 9.50 ml of metal solution. Cu2+ sorption increases slightly with pH to about 60% for MS at pH 6 and then becomes constant up to pH 8 when sorption rises to completion. Preliminarycharacterization of the actual powder by proton nuclear magnetic resonance showed clear presence of amide (-CO-N-H), benzenoid (Ar-H), saturated alkyl and unsaturated fragments in both MS and MO. The mass spectrum showed the presence of amino (R-NH2) fragments. The remarkable heavy metal sorption ability of M. stenopetala and M. oleifera could thus be attributable to, among other mechanisms,coordination or complex formation between the metal cations and pH dependent oxygen and nitrogen anionic sites of the Moringa proteins

L'educació dels valors democràtics a l'etapa d'educació infantil. Estudi d'un centre educatiu

S'exposa la recerca efectuada en una escola pública sobre l'educació dels valors democràtics a l'etapa d'educació infantil. A partir de l'anàlisi del projecte educatiu, d'entrevistes a docents i alumnes, i d'observacions, es posa de manifest l'autonomia del professorat a l'hora de treballar els valors amb el seu grup i la gran implicació de la comunitat escolar en l'educació emocional. Tot i haver-hi una gran coherència entre els documents del centre i els valors educats, hi apareixen alguns desacords entre docents. S'observa l'existència de diversos factors que intervenen en l'aprenentatge dels valors en els infants

Cell adhesion on UV-crosslinked polyurethane gels with adjustable mechanical strength and thermoresponsiveness

Temperature-responsive polyurethane (PU) hydrogels represent a versatile material platform for modern tissue engineering and biomedical applications. However, besides intrinsic advantages such as high mechanical strength and a hydrolysable backbone composition, plain PU materials are generally lacking bio-adhesive properties. To overcome this shortcoming, the authors focus on the synthesis of thermoresponsive PU hydrogels with variable mechanical and cell adhesive properties obtained from linear precursor PUs based on poly(ethylene glycol)s (pEG) with different molar masses, isophorone diisocyanate, and a dimerizable dimethylmaleimide (DMMI)-diol. The cloud point temperatures of the dilute, aqueous PU solutions depend linearly on the amphiphilic balance. Rheological gelation experiments under UV-irradiation reveal the dependence of the gelation time on photosensitizer concentration and light intensity, while the finally obtained gel strength is determined by the polymer concentration and spacing of the crosslinks. The swelling ratios of these soft hydrogels show significant changes between 5 and 40 °C whereby the extent of this switch increases with the hydrophobicity of the precursor. Moreover, it is shown that the incorporation of a low amount of catechol groups into the networks through the DMMI dimerization reaction leads to strongly improved cell adhesive properties without significantly weakening the gels

Penalty-based heuristic direct method for constrained global optimization

This paper is concerned with an extension of the heuristic DIRECT method, presented in[8], to solve nonlinear constrained global optimization (CGO) problems. Using a penalty strategy based on a penalty auxiliary function, the CGO problem is transformed into a bound constrained problem. We have analyzed the performance of the proposed algorithm using fixed values of the penalty parameter, and we may conclude that the algorithm competes favourably with other DIRECT-type algorithms in the literature.The authors wish to thank two anonymous referees for their comments and suggestions to improve the paper. This work has been supported by FCT – Fundação para a Ciência e Tecnologia within the R&D Units Project Scope: UIDB/00319/2020, UIDB/00013/2020 and UIDP/00013/2020 of CMAT-UM

On parallel Branch and Bound frameworks for Global Optimization

Branch and Bound (B&B) algorithms are known to exhibit an irregularity of the search tree. Therefore, developing a parallel approach for this kind of algorithms is a challenge. The efficiency of a B&B algorithm depends on the chosen Branching, Bounding, Selection, Rejection, and Termination rules. The question we investigate is how the chosen platform consisting of programming language, used libraries, or skeletons influences programming effort and algorithm performance. Selection rule and data management structures are usually hidden to programmers for frameworks with a high level of abstraction, as well as the load balancing strategy, when the algorithm is run in parallel. We investigate the question by implementing a multidimensional Global Optimization B&B algorithm with the help of three frameworks with a different level of abstraction (from more to less): Bobpp, Threading Building Blocks (TBB), and a customized Pthread implementation. The following has been found. The Bobpp implementation is easy to code, but exhibits the poorest scalability. On the contrast, the TBB and Pthread implementations scale almost linearly on the used platform. The TBB approach shows a slightly better productivity