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This paper studies the determinants of technological catch-up considering spatial and sectoral aggregation of industries. We investigate how geographical and technological proximity to the technology leader impact regional employment growth. We model technological progress by means of a hierarchical process of catch-up to the technology leader. We also incorporate measures for knowledge spillover effects to test the roles of competition, specialisation, and diversity at the industry level. Empirical results using data at the county level for different economic sectors (2-dig NAICS) for the United States indicate that human capital plays a crucial role in promoting sectoral employment growth. The association between technological/geographical distance to the technology leader and employment growth varies across sectors.

Although the content of Mg2+ in hard tissues is very low (typically 1.5wt%), its incorporation into synthetic hydroxyapatite (HAp) particles and its role in the mineral's properties are still subject of intensive debate. A combined experimental-computational approach is used to answer many of the open questions. Mg2+-enriched HAp particles are prepared using different synthetic approaches and considering different concentrations of Mg2+ in the reaction medium. The composition, morphology and structure of the resulting particles are investigated using X-ray photoelectron spectroscopy, energy dispersive X-ray spectroscopy, scanning and transmission electron microscopies, FTIR, and wide-angle X-ray diffraction. After this scrutiny, the role of the Mg2+ in the first nucleation stages, before HAp formation, is investigated using atomistic molecular dynamics simulations. Saturated solutions are simulated with and without the presence of DNA, which has been recently used as a soft template in the biomineralization process. This synergistic investigation provides a complete picture of how Mg2+ ions affect the mineralization from the first stages onwards, Postprint (published version)

Los objetivos de esta investigación son conocer la relación existente entre la alineación estratégica (AE),la cultura organizacional (CO), los procesos de innovación (INN) y las prácticas de flexibilidad laboral(PFL) con la percepción del desempeño empresarial desde la perspectiva del trabajador. Para estos efectos utilizamos un análisis d tipo cuantitativo con una muestra de 98 personas que trabajan en empresas con más de 500 trabajadores. Para este estudio definimos desempeño empresarial en 5 formas alternativas: iniciativa y creatividad (IC), objetivos alcanzados (OA), satisfacción del trabajador (ST), evolución rápida del trabajador (EO) y aprovechamiento de los recursos (AR). Los resultados preliminares indican que la CO y la AE tienen un efecto inequívoco en promover el desempeño de la empresa, independientemente de la definición que se utilice. Sin embargo, la INN y las PFL tienen efectos no simétricos en el desempeño de la empresa; estos resultados dependen de la definición de desempeño que sea utilizada, es decir, las empresas enfrentan una disyuntiva en la definición de los objetivos de desempeño y los procesos de flexibilidad organizacional a seguir. En resumen, los procesos de INN y las PFL trabajan de manera opuesta en el alcance de los objetivos de desempeño, y no dan unidireccionalmente una ventaja competitiva y sostenible.

Encapsulation of DNA into hydroxyapatite (HAp) has been investigated using a rational approach that involves computer simulation and experimental techniques. The temporal evolution of the radial distribution functions derived from atomistic molecular dynamics simulations of Ca2+, PO4 3− and OH−-containing aqueous solutions in the presence and absence of B-DNA has been used to conclude that the backbone of the double helix acts as a template for HAp growth. More specifically, results reveal the formation of calcium phosphate clusters at the first stages of the simulations, which subsequently reorganize to nucleate HAp. This effect is produced in the absence and, especially, presence, of DNA indicating that the biomolecules do not inhibit but even promote mineral growth. Furthermore, computer simulations suggest that the diffusion of the OH− anions through the inorganic solution is the limiting step for the nucleation of the biomineral. Nanocapsules and crystalline nanorods of HAp containing DNA molecules inside have been prepared by mixing solutions containing Ca2+ and PO4 3− ions with fish sperm DNA at high pH. The dimensions and morphology of such nanostructures have been examined by transmission electron microscopy, while the characterization of the biomineral has been focused on the identification of DNA inside HAp using infrared, X-ray photoelectron and UV-vis spectroscopies, as well as gel electrophoresis. The biominerals reported in this work are important for biomedical applications requiring the protection of DNA from aggressive environmental conditions, Postprint (published version)

Hydroxyapatite (HAp) particles with very different surface charges and compositions (i.e. different Ca/P and CO32-/PO43- ratios) have been obtained by varying the experimental conditions used during the chemical precipitation process. The DNA adsorption capacity and protection imparted against the attack of nucleases of HAp particles have been proved to depend on the surface charge while the buffering capacity is affected by the chemical composition. On the basis of both the surface charge and the crystallinity, the predominant planes at the surfaces of HAp particles have been identified. Atomistic molecular dynamics simulations of surfaces constructed with these planes (i.e. (001) and the two terminations of (010)) with the adsorbed B-DNA double helix have been performed to get microscopic understanding of the influence of the mineral in the biomolecule structure and the interaction energies. The results indicate that the DNA secondary structure is perfectly preserved on the (001) surface, this stability being accompanied by an attractive binding energy. In contrast, the (010) surface with PO43-, OH- and Ca2+ ions in the termination induces significant local and global deformations in the double helix, repulsive OH-(HAp)/PO43- (DNA) interactions provoking the desorption of the biomolecule. Finally, although the termination of the (010) surface with PO43- and Ca2+ ions also deforms the double helix, it forms very strong attractive interactions with the biomolecule. These binding characteristics are in excellent agreement with the DNA adsorption and protection abilities experimentally determined for the HAp samples. Finally, the surface charge has been found less decisive than the chemical composition in the efficacy of the transfection process., Peer Reviewed, Postprint (published version)

This study develops a model of corporate social responsibility (CSR) behavior that is compatible with both the mutual goals of profit maximization and the reduction of global warming effects. The theory developed in this paper indicates that, under perfect competitive and unregulated markets, firms must take an innovative entrepreneurship approach to reduce global warming externalities, and, consequently, respond to the demands of stakeholders to behave in a CSR fashion. In this setting, managers and firms find incentives to pursue strategies leading to horizontal differentiation when a segment of the market has strong revealed consumption preferences for environmentally friendly products, and when consumers derive a consumption disutility from products creating global warming effects. To achieve these goals, firms using a safe technology also incur certification/labeling costs in order to gain market power. That is, this study demonstrates that, in unregulated competitive markets, efforts to clearly identify sources of global warming effects require innovative entrepreneurship thinking above and beyond government regulatory efforts. Thus, firms behaving in a CSR fashion may achieve monopolistic power, and therefore positive profits. In sum, our model demonstrates that CSR is compatible with the triple bottom line of economic, social and environmental performance.

The development and improvement of non-viral vectors on genetic engineering has been the subject of study of many researchers due to its advantages as compared to its viral counterparts. Among the numerous studied non-viral vectors, hydroxyapatite particles (HAP) have been traditionally used for genetic transfection assays due to its strong interactions with nucleic acids, low cost, low toxicity, high biocompatibility and ease of fabrication. Amid employed vector synthesis techniques, chemical co-precipitation is most popular. It consists of apatite crystal formation as a consequence of precipitation reactions brought upon by addition of a phosphate source to an aqueous calcium solution. DNA adsorption occurs on the surface of the generated apatite material. However attractive, chemical co-precipitation presents various shortcomings such as poor morphology control, poor particles size control, aggregates formation and DNA exposure. All these characteristics have been pointed out by several authors as some of the factors contributing and leading to low transfection levels. Within this context, the present study exhibits the successful encapsulation of DNA with HAP nanoparticles produced by a synthesis protocol based on chemical precipitation. The obtained nanocapsules showed a primarily spherical morphology and good dispersion. Moreover, the protecting effect of HAP capsule material upon DNA integrity was confirmed by endonucleases attack studies as well as genetic material liberation under acidic biomimetic environment. Finally, the transfection viability of the synthesized nanoparticles was successfully evaluated by means of bacterial transformation under in-vitro conditions, thus demonstrating the biotechnological potential as non-viral vectors.

Durante el 2009 se realizó un diagnóstico de la ges- tión de desechos químicos en la Universidad Na- cional, tanto en laboratorios de docencia como de investigación. Para recopilar la información: 1) se aplicó un cuestionario, una entrevista y se hizo una visita (inspección) a los laboratorios; 2) se realizaron inventarios de desechos químicos; 3) se efectuaron sesiones de trabajo con funcionarios encargados de la gestión universitaria; y 4) se visitó a funcionarios de instituciones públicas y privadas encargados de la gestión de desechos. Con el presente trabajo, se identificaron las condicio- nes actuales de manipulación y disposición final de los desechos químicos en la Universidad Nacional, así como los procedimientos o gestiones administra- tivos que ejecutan las autoridades universitarias para su adecuada manipulación. Se concluye que para una gestión adecuada de de- sechos químicos en la Universidad Nacional es ne- cesario formular e implementar una normativa, a nivel nacional e institucional, enfocada al quehacer universitario, así como la creación de una oficina que se encargue de coordinar todas las actividades y procedimientos relacionados con el manejo de los desechos químicos.

The academic activities carried out at the School of Chemistry make indispensable to develop actions oriented toward the consolidation of a reagent and residue management system, especially in the teaching laboratories. The project “Management of reagents and residues in the teaching laboratories of the School of Chemistry” works under the Green Chemistry values which designs products and chemical processes that reduce or eliminate the use and production of dangerous substances, to benefit the environment. With a preventive vision, a change from the laboratory practices is looked to select those with less environmental impact. Additionally, residue quantification is made and its management protocols are developed for each practice. The project has several stages: diagnose, action implementation, student, teacher and administration personnel training and evaluation during the process and at the end of it. The article describes methodological aspects of the project operation emphasizing on reagent and residue quantification through flow diagrams., Las actividades académicas que se realizan en la Escuela de Química hacen indispensable la puesta en marcha de acciones orientadas a la consolidación de una gestión de los reactivos y residuos, especialmente en los laboratorios de docencia. El proyecto “MANEJO DE REACTIVOS Y RESIDUOS EN LOS LABORATORIOS DE DOCENCIA DE LA ESCUELA DE QUÍMICA” orienta su quehacer en los principios de Química Verde, la cual se ocupa del diseño de productos o procesos químicos que reducen o eliminan el uso y producción de sustancias peligrosas, en beneficio del ambiente. Con una visión preventiva, se procura un cambio desde las mismas prácticas de laboratorio al seleccionar las que causen un menor impacto al ambiente. Además se realiza una cuantificación rigurosa de los residuos y el desarrollo de protocolos de manejo de los mismos para cada una de las prácticas. El proyecto se desarrolla en varias etapas: diagnóstico, implementación de acciones, capacitación de estudiantes, personal docente y administrativo y evaluación durante el proceso yal final. El artículo destaca aspectos metodológicos de la puesta en marcha de este proyecto, y enfatiza en la cuantificación de reactivos y residuos a través de diagramas de flujo.