A binary polymeric blend was prepared using chitosan (CS) and polyvinyl alcohol (PVA) at a ratio of 80:20, respectively, to obtain a solid polymeric electrolyte with possible application for the ...generation of an electric current in proton or anion exchange electrochemical cells. With a 6% m/m solution, a membrane was formed using the electrospinning technique, and the influence of the incorporation of titanium oxide (TiO2) nanoparticles, at a concentration between 1000 and 50,000 ppm, on the physicochemical properties of the material was evaluated. The micrographs obtained by SEM revealed that the diameter of the nanofibers was close to 100 nm. Likewise, it was found that the incorporation of the nanoparticles affected the moisture absorption of the material, reaching a predominantly hydrophobic behavior in the composite with the highest concentrations of these (2% absorption), while for the lowest content of the filler, the absorption reached values close to 13%. On the other hand, Thermogravimetric Analysis (TGA) showed lower dehydration in the fibrous composite with a 1000 ppm TiO2 content, while Differential Scanning Calorimetry (DSC) showed that these nanoparticles did not significantly affect the thermal transition (Tm) of the composite. Additionally, with the incorporation of nanoparticles, a shift in the Tg from 44 to 37 °C was found concerning the unfilled binary membrane, which increased the possibility of achieving higher ionic conductivities with the nanocomposites at room temperature. Complex Impedance Spectroscopy determined the material’s activation energy, decreasing this by adding the TiO2 filler at a concentration of 1000 ppm. On the other hand, when the membranes were doped with a 1 M KOH solution, the fibrous structure of the membrane changed to a porous cork-like configuration. In future research, the electrospun membrane could be used in the development of a composite to validate the energy efficiency of the new solid polymer electrolyte.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
The proton-proton and proton-antiproton inelasticity profiles in the impact parameter display very interesting and sensitive features which cannot be deduced solely from the current large body of ...highenergy scattering data. In particular, phenomenological studies exhibit a link between the ratio of the real to imaginary parts of the elastic scattering amplitude at a finite momentum transfer, and the corresponding change of character of the inelastic processes from central to peripheral collisions. We describe how a theoretical model, accommodating the existing data, based on the Regge hypothesis including both the Pomeron and odderon as double poles, and ω and f mesons as single poles in the complex-J plane, generates a hollow in the inelasticity at low impact parameters. The hollowness effect, which generally may be sensitive to model details, does unequivocally take place both for pp and pp¯ collisions within the applied Regge framework, indicating inapplicability of inelasticity-folding geometric approaches.
Parametrizations of the pp scattering data at the LHC collision energies indicate a hollow in the inelasticity profile of the pp interaction, with less absorption for head-on collisions than at a ...nonzero impact parameter. We show that some qualitatively unnoticed features may be unveiled by a judicious application of the inverse scattering problem in the eikonal approximation and interpretation within an optical potential model. The hollowness effect is magnified in a 3D picture of the optical potential, and will presumably be enhanced at yet higher energies. Moreover, in 3D it sets in at much smaller energies than at the LHC. We argue that hollowness in the impact parameter is a quantum effect, relying on the build-up of the real part of the eikonal scattering phase and its possible passage through π/2. We also show that it precludes models of inelastic collisions where inelasticity is obtained by naive folding of partonic densities.
Objetivo/Contexto: este trabajo estudia las migraciones asquenazíes que arribaron a Colombia durante el siglo xix y su papel como intermediarias en la transformación capitalista del país, a través de ...la red transatlántica que conformó, durante cuatro generaciones, la familia extensa Stiebel, Schloss, Koppel y Kopp entre Frankfurt, Londres, Manchester y Bogotá, vía Kingston y Cartagena. Metodología: se revisaron una gran cantidad de documentos relacionados con sus integrantes y con las casas comerciales Schloss Brothers, Stiebel Brothers, Koppel & Schloss, Kopp & Castello y Leo S. Kopp & Cía. conservados en distintos archivos en Alemania, Inglaterra, Jamaica y Colombia, y en las plataformas virtuales de investigación genealógica MyHeritage y FamilySearch. Gracias a esto, fue posible reconstruir con mucho detalle la cronología de sus lugares de tránsito, las características de sus actividades comerciales y muchos aspectos de sus biografías. Originalidad: este trabajo incorpora la etnicidad como una variable relevante en la historiografía económica y empresarial de Colombia, específicamente la importancia de la identidad judía de muchos de los extranjeros que llegaron al país después de la Independencia y que, gracias a ella, se convirtieron en agentes privilegiados de su comercio exterior. Además, contribuye al estudio de las migraciones judías a Colombia, fenómeno poco abordado por los académicos. Conclusiones: todo esto pone en evidencia el papel fundamental de la comunidad transatlántica que conformaron los migrantes asquenazíes al servir tanto a los intereses del Imperio británico sobre la América española como al proyecto de las élites de las nuevas repúblicas hispanoamericanas que buscaron insertarlas dentro del sistema global de la economía capitalista, en este caso, a Colombia en los circuitos del comercio transatlántico.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Optimizing production systems is urgent and indispensable if companies are to cope with global competition and a move from mass production to mass customization. The urgency of this need is more ...obvious in old production plants with a history of modifications, expansions, and adaptations in their production facilities. It is common to find complex, intricate and inefficient systems of material and product flows as a result of poor production facility layout. Several approaches can be used to support the design of optimal facility layouts. However, there is a lack of a suitable generic methodology for designing such layouts. Additionally, there has been little focus on the data and resources required, or on how simulation and optimization can support the design of optimal facilities. To overcome these deficiencies, this paper studies the integration of simulation and optimization for the design and improvement of facility layouts taking into account production and logistics constraints. The paper includes a generic perspective and a detailed implementation. The proposed methodology is evaluated in two case studies and by drawing on the principles and tools of the functional resonance analysis method. This method analyzes the implementation order and variability of a group of processes that can lead to unwanted outcomes. The results can provide managers and other stakeholders with a methodology that adequately considers production and logistics constraints when seeking an optimized facility layout design.
Abstract This study investigates a largely unexplored area by examining how internationalization, firm age, and environmental turbulence influence the key components of strategic agility, namely ...strategic sensitivity, leadership unity, and resource fluidity. Although these factors have been identified as potential catalysts for strategic agility, their specific impacts on strategic agility’s core capabilities have yet to be thoroughly explored. Our research aims to bridge this gap, providing a nuanced understanding of how each of these variables shapes the strategic agility of a firm. The study uses the empirical research of 220 Spanish firms in the service sector and then adopts partial least squares structural equation modeling to analyze the data. Our findings indicate that internationalization has a dual effect on strategic agility: internationalization enhances strategic sensitivity, reflecting improved environmental awareness, but it diminishes leadership unity, illustrating the complexities of global leadership alignment. Additionally, an increase in firm age is associated with a decrease in all the aspects of strategic agility. By contrast, environmental turbulence positively impacts each dimension of strategic agility, suggesting that turbulent conditions can indeed promote the adaptability and responsiveness of a firm.
Rhizobia are soil proteobacteria able to engage in a nitrogen-fixing symbiotic interaction with legumes that involves the rhizobial infection of roots and the bacterial invasion of new organs formed ...by the plant in response to the presence of appropriate bacterial partners. This interaction relies on a complex molecular dialogue between both symbionts. Bacterial
-acetyl-glucosamine oligomers called Nod factors are indispensable in most cases for early steps of the symbiotic interaction. In addition, different rhizobial surface polysaccharides, such as exopolysaccharides (EPS), may also be symbiotically relevant. EPS are acidic polysaccharides located out of the cell with little or no cell association that carry out important roles both in free-life and in symbiosis. EPS production is very complexly modulated and, frequently, co-regulated with Nod factors, but the type of co-regulation varies depending on the rhizobial strain. Many studies point out a signalling role for EPS-derived oligosaccharides in root infection and nodule invasion but, in certain symbiotic couples, EPS can be dispensable for a successful interaction. In summary, the complex regulation of the production of rhizobial EPS varies in different rhizobia, and the relevance of this polysaccharide in symbiosis with legumes depends on the specific interacting couple.
Aim
A series of knowledge has been developed on burnout syndrome in the sports context that has allowed to generate a solid theoretical structure that requires new contributions to delve into those ...aspects that have been less addressed, as is the case of optimism and resilience when it comes to linking them to the syndrome in top-performance athletes. For this purpose, the Burnout Inventory for Athletes (IBD-r), the Resilience Scale adapted to Spanish, and the Life Orientation Scale-Revised (LOT-R) for optimism were used.
Methods
From this perspective, the study was approached with 121 Uruguayan athletes who participated in the last Pan-American Games, assuming practically all the subjects who have this level of sport (142) considering gender and type of sport.
Results
The results indicate that 67% of the sample presents burnout symptoms for the emotional exhaustion dimension, and moderate resilience and optimism. Although there are no significant differences attributable to gender or type of sport, this contribution allows us to continue focusing on future work and further analysis. The type of sport presented statistically significant differences in relation to the personal competence dimension and the type of sport.
Conclusion
Resilience and optimism obtained a clear influence on the occurrence of burnout, in a statistically negative sense, showing themselves as interesting prevention strategies for future lines of research, where it is essential to design interventions that teach emotional skills to manage adversity and prevent burnout.
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