Effect of Sb on the quantum efficiency of GaInP solar cells

The energy bandgap of GaInP solar cells can be tuned by modifying the degree of order of the alloy. In this study, we employed Sb to increase the energy bandgap of the GaInP and analyzed its impact on the performance of GaInP solar cells. An effective change in the cutoff wavelength of the external quantum efficiency of GaInP solar cells and an effective increase of 50 mV in the open‐circuit voltage of GaInP/Ga(In)As/Ge triple junction solar cells were obtained with the use of Sb. Copyright © 2016 John Wiley & Sons, Ltd.     

Permeability Study of Polyphenols Derived from a Phenolic-Enriched Hibiscus sabdariffa Extract by UHPLC-ESI-UHR-Qq-TOF-MS

Previous findings on the capacity of Hibiscus sabdariffa (HS) polyphenols to ameliorate metabolic disturbances justify the necessity of studies oriented to find the potential metabolites responsible for such an effect. The present study examined the intestinal epithelial membrane permeability of polyphenols present in a phenolic-enriched Hibiscus sabdariffa extract (PEHS), free and encapsulated, using the Caco-2 cell line. Additionally, selected polyphenols (quercetin, quercetin-3-glucoside, quercetin-3-glucuronide, and N-feruloyltyramine) were also studied in the same absorption model. The powerful analytical platform used ultra-high-performance liquid chromatography coupled with ultra-high-resolution quadrupole time-of-flight mass spectrometry (UHPLC-ESI-UHR-Qq-TOF-MS), and enabled the characterization of seven new compounds in PEHS. In the permeation study, only a few compounds were able to cross the cell monolayer and the permeability was lower when the extract was in an encapsulated form. Pure compounds showed a moderate absorption in all cases. Nevertheless, these preliminary results may need further research to understand the complete absorption mechanism of Hibiscus polyphenols.     

$${ SIM}^2{ RRAM}$$: a physical model for RRAM devices simulation

In the last few years, resistive random access memory (RRAM) has been proposed as one of the most promising candidates to overcome the current Flash technology in the market of non-volatile memories. These devices have the ability to change their resistance state in a reversible and controlled way applying an external voltage. In this way, the resulting high- and low-resistance states allow the electrical representation of the binary states “0” and “1” without storing charge. Many physical models have been developed with the aim of understanding the mechanisms that control the resistive switching. In this work, we have compiled the main theories accepted as well as their corresponding models for the conduction characteristics. In addition, simulation tools play a very important role in the task of checking these theories and understanding these mechanisms. For this reason, the simulation tool called \(\hbox {SIM}^{2}\hbox {RRAM}\) has been presented. This simulator is capable of replicating the global behavior of RRAM cell based on \(\hbox {HfO}_{x}\).     

Optimal cost design with sensitivity analysis using decomposition techniques. Application to composite breakwaters

Minimizing the expected total cost of a structure, including maintenance and construction is a difficult problem because of the presence in the objective function of the yearly failure rates, which have to be calculated by an optimization problem per each failure mode. In this paper, a new method for the design of structures that minimizes the total expected costs of the structure during its lifetime based on Benders’ decomposition is presented. In addition, some tools for sensitivity analysis are introduced, which make it possible to determine how the cost and yearly failure rates of the optimal solution are affected by small changes in the input data values. The proposed method is illustrated by its application to the design of a composite breakwater under breaking and non-breaking wave conditions.     

Assessment of seasonal and polluting effects on the quality of river water by exploratory data analysis

22 Physico-chemical variables have been analyzed in water samples collected every three months for two and a half years from three sampling stations located along a section of 25 km of a river affected by man-made and seasonal influences. Exploratory analysis of experimental data have been carried out by box plots, ANOVA, display methods (principal component analysis) and unsupervised pattern recognition (cluster analysis) in an attempt to discriminate sources of variation of water quality. PCA has allowed the identification of a reduced number of “latent” factors with a hydrochemical meaning: mineral contents, man-made pollution and water temperature. Spatial (pollution from anthropogenic origin) and temporal (seasonal and climatic) sources of variation affecting quality and hydrochemistry of river water have been differentiated and assigned to polluting sources. An ANOVA of the rotated principal components has demonstrated that (i) mineral contents are seasonal and climate dependent, thus pointing to a natural origin for this polluting form and (ii) pollution by organic matter and nutrients originates from anthropogenic sources, mainly as municipal wastewater. The application of PCA and cluster analysis has achieved a meaningful classification of river water samples based on seasonal and spatial criteria.     

Effect of the nutritional recovery on the concentration of Interleukin-2 in severely malnourished children

The severely malnourished child has dysfunction of the immune response that may increase the risk of morbidity or mortality due to infectious diseases, therefore, the purpose of this study was to demonstrate the effect of intensive nutritional support on the cellular and serum concentration of IL-2 and CD4+, as well as CD8+ T cells in children with severe protein energy malnutrition. A clinical assay was carried out in a tertiary care hospital. 10 severely malnourished children < 48 months of age who received formula without lactose via enteral feeding for two weeks and ad libitum for an additional two weeks were included. Cellular and serum concentrations of IL-2 and the subpopulation of CD4+ and CD8+ were obtained. A control group (n = 13) was included. A paired student t test for initial-final determinations and the Mann-Whitney Test for comparison with control group were used, and null hypothesis was rejected with a p value < 0.05. There was a noteworthy increase in the comparison between the initial vs. final percentage of the cellular expression of IL-2 (p < 0.001) and in the serum concentration of IL-2 (p = 0.001). Therefore, four weeks of nutritional recovery significantly restored the production of IL-2, independently of the nutrients involved in the process, although, the rate of restoration seems to depend on the severity of the children primary PEM.     

Entropy considerations in monomolecular cracking of alkanes on acidic zeolites

Compensation between adsorption entropies and enthalpies results in less than a two-fold variation in adsorption equilibrium constants for C₃–C₆ alkanes at temperatures relevant for monomolecular cracking; the size-independent activation energy for CC bond activation in C₃–C₆ alkanes indicates that the marked increase in monomolecular cracking turnover rates observed with alkane chain size reflects a concurrent increase in activation entropies. Thermodynamic treatments for non-ideal systems rigorously describe confinement effects within zeolite channels and show that pre-exponential factors depend on solvation effects of the zeolite-host environment through variations in the thermodynamic activity of the zeolitic proton. Observed differences in rates and selectivities of monomolecular alkane activation with zeolite structure, after normalization to intrazeolitic concentrations, reflect differences in intrinsic rate constants.     

Modeling and experimental studies of emulsion copolymerization systems. II. Styrenics

Using a model previously published, predictions for evolution of conversion and average particle diameter in batch experiments are compared against experimental data for four emulsion copolymerizations of styrene with the following monomers: (1) methyl methacrylate, (2) butyl acrylate, (3) butadiene, and (4) acrylic acid. For each copolymerization system the experiments covered simultaneous variations in five variables: initiator and surfactant concentrations, water to monomer ratio, monomer composition, and temperature. It is shown that after data fitting for unknown or uncertain parameters, the model is capable of explaining quantitatively the experimental observations for conversion evolution and only qualitatively the particle size evolution data. This points out to the possible contribution of particle nucleation mechanisms other than the micellar one, which is the only mechanism included in the model. Some of the adjustable parameter values were found to depend on the copolymer composition. The only case in which the model does not perform well is in the prediction of the effect of initiator concentration on the copolymerization rate for butadiene‐rich formulations. It is also found that the model predictions are very sensitive to the value of the diffusion coefficients of monomeric radicals in the copolymer particle, which are not readily available in the literature. It is concluded that it is important to independently measure these parameters in order to enhance the predictive power of models. It is also concluded that the model can be useful for practical applications. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 79: 2380–2397, 2001     

Changes in olive oil components during deodorization and/or physical refining at the pilot plant scale using nitrogen as stripping gas

A detailed study has been performed of the changes made by the action of the independent variables (temperature, flow of stripping gas, thickness of oil layer in the deodorizer, and length of the process) on different quality parameters of olive oil deodorized and/or physically refined in a discontinuous process (in a pilot plant of 250 kg maximum capacity using nitrogen as stripping gas in place of steam). The changes caused in the contents of unsaturated fatty acids (elaidinization) in the contents of 3,5-stigmastadiene (dehydrated beta sitosterol), and of saturated fatty acids in the β-position have been studied. A bleached olive oil with 1.85% of ffa was analyzed in a design of experiments using a modified Yates factorial statistical analysis. The results obtained from similar assays carried out with bleached sunflower seed oil with 0.56°C of acidity (using a 4 × 4 latin square experimental scheme) were used as starting point to select the most important independent variables. It has been concluded that the content of trans fatty acids in the deodorized oils depends indirectly on the four variables, and although the elaidic acid content is correct in all cases, the content of trans 18:2 and trans 18:3 readily exceeds the permitted limit when the temperature is above 250°C and the residence times are long. The same occurs with the content of saturated fatty acids in β-position of triglycerides and the content of 3,5-stigmastadiene. This means that the oil must be deodorized at a lower temperature, with longer residence time and greater energy spending. As the different olive oils have different initial characteristics, it is of interest to establish criteria, which are able to forecast whether a particular oil could be refined under pre-set conditions. A similar study should be made to obtain refined oils in other plants.     

New Insights on the Role of Connexins and Gap Junctions Channels in Adipose Tissue and Obesity

Due to the inability to curb the excessive increase in the prevalence of obesity and overweight, it is necessary to comprehend in more detail the factors involved in the pathophysiology and to appreciate more clearly the biochemical and molecular mechanisms of obesity. Thus, understanding the biological regulation of adipose tissue is of fundamental relevance. Connexin, a protein that forms intercellular membrane channels of gap junctions and unopposed hemichannels, plays a key role in adipogenesis and in the maintenance of adipose tissue homeostasis. The expression and function of Connexin 43 (Cx43) during the different stages of the adipogenesis are differentially regulated. Moreover, it has been shown that cell–cell communication decreases dramatically upon differentiation into adipocytes. Furthermore, inhibition of Cx43 degradation or constitutive overexpression of Cx43 blocks adipocyte differentiation. In the first events of adipogenesis, the connexin is highly phosphorylated, which is likely associated with enhanced Gap Junction (GJ) communication. In an intermediate state of adipocyte differentiation, Cx43 phosphorylation decreases, as it is displaced from the membrane and degraded through the proteasome; thus, Cx43 total protein is reduced. Cx is involved in cardiac disease as well as in obesity-related cardiovascular diseases. Different studies suggest that obesity together with a high-fat diet are related to the production of remodeling factors associated with expression and distribution of Cx43 in the atrium.