Aplicación de la técnica mapas mentales para desarrollar la compresión lectora en los estudiantes del primer ciclo de la Facultad de Ciencias Empresariales de la Universidad Técnica de Machala - Ecuador - 2013

Publicación a texto completo no autorizada por el autorAplica la técnica de mapas mentales para desarrollar la comprensión lectora en los estudiantes del primer ciclo de la Facultad De Ciencias Empresariales de la Universidad Técnica de Machala. El diseño empleado fue el cuasi experimental. El estudio se desarrolló durante el segundo semestre del año 201con una muestra de 144 estudiantes de ambos sexos pertenecientes a la Facultad de Ciencias empresariales de la Universidad Técnica de Machala. Los niveles de comprensión lectora fueron evaluados antes y después de la aplicación de la técnica de mapas mentales mediante la prueba de comprensión lectora. Se utilizó también el instrumento para evaluar mapas mentales, de Suárez y García. Los resultados permiten concluir que la aplicación de la técnica de mapas mentales ha producido un incremento significativo en los niveles de comprensión lectora de la población estudiada.Tesi

Metal cofactor modulated folding and target recognition of HIV-1 NCp7.

The HIV-1 nucleocapsid 7 (NCp7) plays crucial roles in multiple stages of HIV-1 life cycle, and its biological functions rely on the binding of zinc ions. Understanding the molecular mechanism of how the zinc ions modulate the conformational dynamics and functions of the NCp7 is essential for the drug development and HIV-1 treatment. In this work, using a structure-based coarse-grained model, we studied the effects of zinc cofactors on the folding and target RNA(SL3) recognition of the NCp7 by molecular dynamics simulations. After reproducing some key properties of the zinc binding and folding of the NCp7 observed in previous experiments, our simulations revealed several interesting features in the metal ion modulated folding and target recognition. Firstly, we showed that the zinc binding makes the folding transition states of the two zinc fingers less structured, which is in line with the Hammond effect observed typically in mutation, temperature or denaturant induced perturbations to protein structure and stability. Secondly, We showed that there exists mutual interplay between the zinc ion binding and NCp7-target recognition. Binding of zinc ions enhances the affinity between the NCp7 and the target RNA, whereas the formation of the NCp7-RNA complex reshapes the intrinsic energy landscape of the NCp7 and increases the stability and zinc affinity of the two zinc fingers. Thirdly, by characterizing the effects of salt concentrations on the target RNA recognition, we showed that the NCp7 achieves optimal balance between the affinity and binding kinetics near the physiologically relevant salt concentrations. In addition, the effects of zinc binding on the inter-domain conformational flexibility and folding cooperativity of the NCp7 were also discussed

threedimensionalquantitativestructureactivityrelationshipsofbicyclophosphorothionates

为获取双环硫化磷酸酯类化合物的昆虫γ-氨基丁酸（GABA）受体和哺乳动物γ-氨基丁酸受体的亲合选择性定量信息，基于实验所测定的双环硫化磷酸酯类化合物与家蝇及大白鼠GABA受体结合的相对活性数据，以比较分子场分析法进行了三维定量构效关系研究。结果表明，家蝇GABA受体的亲合区域有足够的窨容纳异丙基和异丁基，但大白鼠GABA受体的亲合区域不具有这样的空间

Toward Fundamentals of Confined Catalysis in Carbon Nanotubes

An increasing number of experimental studies have demonstrated that metal or metal oxide nanoparticles confined inside carbon nanotubes (CNTs) exhibit different catalytic activities with respect to the same metals deposited on the CNT exterior walls, with some reactions enhanced and others hindered. In this article, we describe the concept of confinement energy, which enables prediction of confinement effects on catalytic activities in different reactions. Combining density functional theory calculations and experiments by taking typical transition metals such as Fe, FeCo, RhMn, and Ru as models, we observed stronger strains and deformations within the CNT channels due to different electronic structures and spatial confinement. This leads to downshifted d-band states, and consequently the adsorption of molecules such as CO, N-2, and O-2 is weakened. Thus, the confined space of CNTs provides essentially a unique microenvironment due to the electronic effects, which shifts the volcano curve of the catalytic activities toward the metals with higher binding energies. The extent of the shift depends on the specific metals and the CNT diameters. This concept generalizes the diverse effects observed in experiments for different reactions, and it is anticipated to be applicable to an even broader range of reactions other than redox of metal species, CO hydrogenation, ammonia synthesis and decomposition discussed here

Selective Extraction of Collagen Peptides with High Purity from Cod Skins by Deep Eutectic Solvents

This paper reports an efficient and eco-friendly extraction and separation method of collagen peptides from cod skins based on a nascent class of green and sustainable deep eutectic solvents (DESs). Six kinds of DESs were designed and synthesized. On the basis of the principle of high extraction efficiency and high purity, choline chloride–oxalic acid was selected as the optimal extraction solvent. In the process of collagen peptides purification, ethanol was the optimal precipitation reagent due to the low toxicity. Afterward, single factor experiments proved that the extraction efficiency and purity of collagen peptides were influenced by the molar ratios of choline chloride–oxalic acid, extraction temperature, reaction time and solvent-to-solid ratio. Under the optimal conditions, higher and lower molecular weight collagen peptides were obtained. The values of their respective extraction efficiencies were up to 91.57% and 96.01% and the corresponding purity was up to 93.14% and 100%, respectively. Finally, UV–vis and Fourier transform infrared spectrometry were utilized to study the extraction mechanism. The results from this study demonstrate that choline chloride–oxalic acid is a green, efficient and promising solvent for extracting collagen peptides from cod skins

Metal cofactor modulated folding and target recognition of HIV-1 NCp7 - Fig 4

<p>(<b>A</b>) Free energy surface of NCp7 projected on <i>Q</i>_<i>ZF</i>1 and <i>Q</i>_<i>ZF</i>2 at intermediate concentration of Zn²⁺. (<b>B</b>) One-dimensional free energy profiles projected onto the <i>Q</i> value of the ZF2 with the ZF1 well-folded (red) and unstructured (blue), respectively at intermediate zinc concentration. For comparison, the corresponding free energy profiles from the simulations. ‘U’ and ‘F’ denote the unfold and fold states of the ZF1, respectively. with the inter-domain interactions removed are also shown (dots).</p

Cold-Adapted Glutathione S-Transferases from Antarctic Psychrophilic Bacterium Halomonas sp. ANT108: Heterologous Expression, Characterization, and Oxidative Resistance

Glutathione S-transferases are one of the most important antioxidant enzymes to protect against oxidative damage induced by reactive oxygen species. In this study, a novel gst gene, designated as hsgst, was derived from Antarctic sea ice bacterium Halomonas sp. ANT108 and expressed in Escherichia coli (E. coli) BL21. The hsgst gene was 603 bp in length and encoded a protein of 200 amino acids. Compared with the mesophilic EcGST, homology modeling indicated HsGST had some structural characteristics of cold-adapted enzymes, such as higher frequency of glycine residues, lower frequency of proline and arginine residues, and reduced electrostatic interactions, which might be in relation to the high catalytic efficiency at low temperature. The recombinant HsGST (rHsGST) was purified to apparent homogeneity with Ni-affinity chromatography and its biochemical properties were investigated. The specific activity of the purified rHsGST was 254.20 nmol/min/mg. The optimum temperature and pH of enzyme were 25 &deg;C and 7.5, respectively. Most importantly, rHsGST retained 41.67% of its maximal activity at 0 &deg;C. 2.0 M NaCl and 0.2% H2O2 had no effect on the enzyme activity. Moreover, rHsGST exhibited its protective effects against oxidative stresses in E. coli cells. Due to its high catalytic efficiency and oxidative resistance at low temperature, rHsGST may be a potential candidate as antioxidant in low temperature health foods

Synergistic Effect of Zn–Co Bimetallic Selenide Composites for Lithium–Sulfur Battery

Compared with monometallic selenides, heterogeneous bimetallic selenides have rich phase boundaries and superior electrical conductivity. ZnSe/CoSe2 composites were prepared by introducing Zn metal and using ZIF-8/67 as the precursor through the synergistic effect between Zn and Co after selenification. The electrocatalytic conversion of polysulfide is accelerated by ZnSe through chemical adsorption and the catalytic effect. The conductive CoSe2 surface provides a rapid diffusion path for lithium ions, accelerating the conversion of the polysulfide. On the basis of their individual strengths, ZnSe and CoSe2 can jointly promote the smooth adsorptive–diffuse–catalytic conversion process of polysulfide and induce the growth of lithium sulfide around its heterogeneous interface, thus enhancing the electrochemical performance of the lithium–sulfur battery cathode materials. The ZnSe/CoSe2–S electrode, at the optimal Zn-to-Co ratio of 1:1, has a 790.06 mAh g−1 initial specific capacity at 0.2 C and excellent cycling stability at 1 C. After 300 cycles, the final capacity is 300.85 mAh g−1, and the capacity retention rate reaches 82.71%