Estudio de los factores críticos de éxito en las cooperativas de la Republica Bolivariana de Venezuela

La sobrevivencia de las organizaciones en el mundo moderno, no es una tarea fácil, los múltiples y violentos cambios económicos, políticos, sociales, culturales y tecnológicos mantienen a las organizaciones en una permanente reorientación de procesos enmarcados y conceptualizados bajo un enfoque de globalización económica y por altos niveles de competitividad. De hecho, es común observar que las organizaciones exitosas, no están enmarcadas solo en su desempeño económico, sino que más bien están sujetas a un conglomerado de factores críticos que determinan su éxito y por ende su permanencia en el mercado. Muchos estudiosos de las organizaciones atribuyen la sobrevivencia empresarial al control de elementos comunes en muchas organizaciones denominados factores críticos del éxito (F.C.E.). De hecho, la realidad organizacional nos inclina a asumir que los F.C.E. intra organizacionales pueden ser manejables o controlables por una buena gestión empresarial, mientras que factores externos, que pueden escapar a la visión de los gerentes, como las políticas de estado, los planes de desarrollo de un país, la economía local e internacional o simplemente medidas gubernamentales, pueden representar variables en ocasiones imprevisibles, que pudieran perfectamente limitar el éxito organizacional

New polymer-based treatments for the prevention of damage by salt crystallization in stone

Salt crystallization can produce severe damage in porous stones, with a dramatic impact on cultural heritage conservation. Such damage is related to the fact that repulsive forces arise between the salt crystals and the pore wall, generating a disjoining pressure that frequently exceeds the tensile strength of stone. In this paper, new treatments are proposed, aimed at preventing salt damage by depositing a thin layer of polymeric coatings over the stone’s pore surfaces. These coating are expected to change the surface chemistry, eliminating the repulsion between the growing crystals and the pore wall and hence the development of the disjoining pressure. Several biopolymers were tested on these substrates: silica glass, calcite, and calcite subjected to a pre-treatment with diammonium hydrogen phosphate (DAP), aimed at preventing calcite dissolution and acting as an anchoring substrate for the polymer coating. Selected polymer treatments were applied to porous Globigerina limestone samples, which were subjected to crystallization tests with sodium sulfate, obtaining promising results (i.e., significant reduction in stone damage), especially when the polymers were applied after the DAP treatment.This research has also been funded by the Spanish Government (Grants CGL2015-70642-R, CGL2015-73103-EXP), the University of Granada (‘‘Unidad Científica de Excelencia’’ UCE-PP2016-05), the Junta de Andalucía (P11-RNM-7550), and the research group RNM-179 of the Junta de Andalucía

Kinetics and Mechanisms of Acid-pH Weathering of Pyroxenes

his research has been funded by the Spanish Government (grant CGL2015-70642-R and CGL2015-73103-EXP), the European Commission (ERDF funds and ACT_ERA NET no. 691712, PCI2019-111931-2), the Junta de Andalucia (research group RNM179), and the University of Granada (Unidad Cientifica de Excelencia UCE-PP2016-05). LMG acknowledges funding by the Spanish Government FPI (Grant BES-2016-078468). The authors also thank the personnel of the Centro de Instrumentacion Cientifica (CIC; University of Granada) for assistance with ICP-OES, Micro-CT, and SEM analyses. All experimental results discussed here are presented in the main text and Supporting Information S1. The authors thank the anonymous reviewers for the extremely careful and fruitful revision performed, which has significantly improved the original version of the manuscript.Weathering of primary silicate minerals under acidic conditions occurs in contexts as varied as acid mine drainage, volcanic environments, soils, stone monuments subjected to acid rain or Geological Carbon Storage (GCS). Considering the abundance of pyroxenes on the Earth crust, knowledge of their weathering kinetics and mechanisms may help to optimize carbonate yield in GCS. Here we report experimental results from the reaction of the clinopyroxenes augite and diopside in acidic solutions. Dissolution at far-from-equilibrium conditions results in the formation of etch pits where crack initiate and propagate by stress corrosion and pressure exerted by swelling of an amorphous, gel-like Si-rich phase, which precipitates despite the undersaturation of the bulk solution and whose formation is highly controlled by the heterogeneity of the mineral surface and the local transport mechanism. These precipitates are commonly localized within deep etch pits and cracks, characterized by a low fluid renewal where high Si-concentrations can be reached locally, so that supersaturation with respect to amorphous silica can occur. Cracks and silica precipitates are most abundant in the case of augite weathered in flow-through experiments. This is related to its faster reaction rate compared to diopside, most likely due to its higher iron content. Finally, in the case of diopside an amorphous magnesium silicate hydrate (M-S-H) precursor forms, which represents an indirect evidence of the high pH conditions prevailing at the diopside-solution interface during dissolution.Spanish Government European Commission CGL2015-70642-R CGL2015-73103-EXPEuropean Commission (ERDF fund)European Commission European Commission Joint Research Centre 691712 PCI2019-111931-2Junta de Andalucia RNM179University of Granada (Unidad Cientifica de Excelencia) UCE-PP2016-05Spanish Government BES-2016-07846

Carbonation mechanisms and kinetics of lime-based binders: An overview

The reaction of slaked lime with atmospheric CO2 in the presence of humidity leads to the formation of cementing carbonate phases in traditional aerial lime mortars and plasters. This carbonation reaction also affects the setting and degradation of hydraulic lime mortars and modern cement. Here, we present an overview of the existing knowledge on carbonation of lime-based binders, which are experiencing a revival as compatible material for the conservation of the built heritage and new sustainable construction. First, the carbonation reaction is defined and its importance in a range of technical and natural processes is outlined. This sets the ground for presenting a review of existing mechanistic models for the carbonation of lime-based materials, including the recent interface-coupled dissolution-precipitation model, and the understanding of carbonation in terms of non-classical crystallization theory. Kinetics models and experimental results for carbonation of lime-based binders (crystals and powder, as well as mortars/plasters) and its acceleration are presented and discussed. Finally, conclusions and future research directions are indicated.Spanish Government grant PID2021-125305NB-I00 funded by MCIN/ AEI /10.13039/ 501100011033ERDF A way of making EuropeJunta de Andalucía research group RNM-179 and grant P20_00675University of GranadaUnidad Científica de Excelencia UCE-PP2016-05European Commission, H2020 Programme, Marie Skłodowska-Curie Action European Training network – Innovative Training Network (ETN-ITN), SUBlime (grant agreement # 955986)Funding for open access charge: Universidad de Granada/CBU

Consolidation of degraded ornamental porous limestone stone by calcium carbonate precipitation induced by the microbiota inhabiting the stone

El artículo original ha sido publicado por Chemosphere, de la Editorial Elsevier, disponible en: http://www.elsevier.com/wps/find/journaldescription.cws_home/362/description#description http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6V74-4NF2NCX-1&_user=654849&_coverDate=08%2F31%2F2007&_rdoc=1&_fmt=high&_orig=search&_origin=search&_sort=d&_docanchor=&view=c&_acct=C000035398&_version=1&_urlVersion=0&_userid=654849&md5=a44718f997b5057999cd6a5f100b7289&searchtype=aAlthough it has already been shown that calcareous stone can be consolidated by using a bacterially-inoculated culture media, a more user-friendly method is the in situ application of a sterile culture media that is able to activate, among the microbial community of the stone, those bacteria with a potential for calcium carbonate precipitation. In order to test this new method for stone consolidation, non-sterilized decayed porous limestone was immersed in sterile nutritional media. Results were compared to those of the runs in which stone sterilized prior to the treatment was used. The effects of the microbial community on stone consolidation were determined by recording the evolution of the culture media chemistry. The treated stones were tested for mechanical resistance and porosity. Results demonstrate that the tested media were able to activate bacteria from the microbial community of the stone. As a consequence of the growth of these bacteria, an alkalinization occurred that resulted in calcium carbonate precipitation. The new precipitate was compatible with the substrate and consolidated the stone without pore plugging. Therefore, a good candidate to in situ consolidate decayed porous limestone is the application of a sterile culture media with the characteristics specified in the present study.Proyectos MAT2005-03994, MAT2006-05411, CGL2004-03910 Grupo de Investigación de la Junta de Andalucía NMR 179, FQM 195 Departamento de Microbiología; Departamento de Mineralogía y Petrología (Universidad de Granada

Silica-Functionalized Nanolimes for the Conservation of Stone Heritage

The relatively recent development of nanolimes (i.e., alcoholic dispersions of Ca(OH)2 nanoparticles) has paved the way for new approaches to the conservation of important art works. Despite their many benefits, nanolimes have shown limited reactivity, back-migration, poor penetration, and lack of proper bonding to silicate substrates. In this work a novel solvothermal synthesis process is presented by which extremely reactive nanostructured Ca(OH)2 particles are obtained using calcium ethoxide as the main precursor species. Moreover, it is demonstrated that this material can be easily functionalized with silica-gel derivatives under mild synthesis conditions, thereby preventing particle growth, increasing total specific surface area, enhancing reactivity, modifying colloidal behavior, and functioning as self-integrated coupling agents. Additionally, the formation of calcium silicate hydrate (CSH) nanocement is promoted by the presence of water, resulting in optimal bonding when applied to silicate substrates, as evidenced by the higher reinforcement effect produced on treated Prague sandstone specimens as compared to those consolidated with nonfunctionalized commercial nanolime. The functionalization of nanolimes is not only a promising strategy for the design of optimized consolidation treatments for the cultural heritage, but may also have important implications for the development of advanced nanomaterials for building, environmental, or biomedical applications

Unveiling the secret of ancient Maya masons: Biomimetic lime plasters with plant extracts

Ancient Maya produced some of the most durable lime plasters on Earth, yet how this was achieved remains a secret. Here, we show that ancient Maya plasters from Copan (Honduras) include organics and have a calcite cement with meso-to-nanostructural features matching those of calcite biominerals (e.g., shells). To test the hypothesis that the organics could play a similar toughening role as (bio)macromolecules in calcium carbonate biominerals, we prepared plaster replicas adding polysaccharide-rich bark extracts from Copan’s local trees following an ancient Maya building tradition. We show that the replicas display similar features as the organicscontaining ancient Maya plasters and demonstrate that, as in biominerals, in both cases, their calcite cement includes inter- and intracrystalline organics that impart a marked plastic behavior and enhanced toughness while increasing weathering resistance. Apparently, the lime technology developed by ancient Maya, and likely other ancient civilizations that used natural organic additives to prepare lime plasters, fortuitously exploited a biomimetic route for improving carbonate binders performanceSantander Program for the Research and Conservation of Maya Sculpture, at the David Rockefeller Center for Latin American Studies(DRCLAS), Harvard UniversitySpanish Government RTI2018-099565-B-I00 PID2021.125305NBMCIN/AEIERDF Away of making EuropeJunta de AndaluciaUniversity of GranadaUnidad Cientifica de Excelencia UCE PP2016-05Horizon 2020Marie Sklodowska-Curie Action European Training network-Innovative Training Network (ETN-ITN), SUBlime 95598

Degradation of ancient Maya carved tuff stone at Copan and its bacterial bioconservation

We acknowledge funding by the Santander Program for the Research and Conservation of Maya Sculpture, at the David Rockefeller Center for Latin American Studies (DRCLAS), Harvard University; the Spanish Government grant RTI2018-099565-B-I00, the Junta de Andalucia research groups RNM-179 and BIO 103, and the University of Granada, Unidad Cientifica de Excelencia UCE-PP2016-05. We thank the Instituto Hondureno de Antropologia e Historia (IHAH) and the local Santander team at the Maya Sculpture Conservation Laboratory (LACEM) in Copan including Hector Eliud Guerra, Karina Garcia, Adelso Canan, Rufino Membreno, Luis Reina, and Isuara Nereyda Alonso for their help and continuous support, as well as for providing access to this Maya archaeological site and their contribution to the documentation, sampling, and treatment application process. We also thank architectural conservator Laura Lacombe for sampling support, Fulvio di Lorenzo for his help with Rietveld analysis of XRD results, George W. Scherer for his insightful comments on clay swelling damage, and the personnel of the Centro de Instrumentacion Cientifica (CIC) of the University of Granada for their help with TG/DSC, XRD, FRX, mu-CT, FESEM and TEM analyses. We also thank Aurelia Ibanez Velasco for her help with the expansion tests, as well as with the porosity and water absorption analyses, and Jean Battini from Micromeritics France S.A.R.L., for the MIP analyses.Much stone sculptural and architectural heritage is crumbling, especially in intense tropical environments. This is exemplified by significant losses on carvings made of tuff stone at the Classic Maya site of Copan. Here we demonstrate that Copan stone primarily decays due to stress generated by humidity-related clay swelling resulting in spalling and material loss, a damaging process that appears to be facilitated by the microbial bioweathering of the tuff stone minerals (particularly feldspars). Such a weathering process is not prevented by traditional polymer- and alkoxysilane-based consolidants applied in the past. As an alternative to such unsuccessful conservation treatments, we prove the effectiveness of a bioconservation treatment based on the application of a sterile nutritional solution that selectively activates the stone ' s indigenous bacteria able to produce CaCO3 biocement. The treatment generates a bond with the original matrix to significantly strengthen areas of loss, while unexpectedly, bacterial exopolymeric substances (EPS) impart hydrophobicity and reduce clay swelling. This environmentally-friendly bioconservation treatment is able to effectively and safely preserve fragile stones in tropical conditions, opening the possibility for its widespread application in the Maya area, and elsewhere.Santander Program for the Research and Conservation of Maya Sculpture, at the David Rockefeller Center for Latin American Studies (DRCLAS), Harvard UniversitySpanish Government European Commission RTI2018-099565-B-I00Junta de Andalucia RNM-179- BIO 103University of Granada, Unidad Cientifica de Excelencia UCE-PP2016-0

Methodology for ranking customer segments by their suitability for distributed energy resources applications

[EN] A massive implementation of distributed energy resources (DER) requires the development of innovative approaches to identify, based on the energy market requirements, fast track options for such implementation. These approaches should assess the potential for DER of the different customer segments and simulate DER adoption for those with highest potential in order to evaluate accurately the impact of this implementation on the different energy actors. This paper introduces a methodology to asses the DER implementation potential of customer segments based on a multi-criteria analysis, considering DER as including distributed generation (DG), distributed storage (DS) and local trading strategiest(1) (LTS). Application of the methodology to the commercial sector for DG installation, considering different motivations (cogeneration, renewable, emergency generator and peaking power) and the obtained results for five different segments in this sector are presented. (C) 2006 Elsevier Ltd. All rights reserved.This work was completed in the framework of the EUDEEP Integrated Project of the 6th EU RTD Framework Programme. The authors deeply thank all the participants in the projects for their help and support that made this work possible.Alfonso-Solar, D.; Pérez-Navarro, Á.; Encinas Redondo, N.; Álvarez, C.; Rodríguez-García, J.; Alcázar-Ortega, M. (2007). Methodology for ranking customer segments by their suitability for distributed energy resources applications. Energy Conversion and Management. 48(5):1615-1623. doi:10.1016/j.enconman.2006.11.006S1615162348

Análisis del espacio de trabajo de un robot paralelo de 3RRR

Comunicación presentada en las XXIX Jornadas de Automática, Tarragona, 3-5 Septiembre 2008.El objetivo de este artículo es realizar el análisis del espacio de trabajo de un robot paralelo esférico del tipo 3RRR mediante una herramienta matemática desarrollada en Matlab. Este 3RRR contiene una particularidad que lo diferencia con respecto a los robots esféricos comunes debido a las exigencias de su aplicación: su centro de rotación no se encuentra en el centro del robot. Basándonos en un parámetro que define la habilidad o destreza del robot (dexterity), calcularemos el valor de las variables que optimizan su espacio de trabajo