Biomimetic chitosan-mediated synthesis in heterogeneous phase of bulk and mesoporous silica nanoparticles

Both bulk and mesoporous silica nanoparticles can be obtained in the form of granular aggregates using chitosan flakes as additive under very soft biomimetic reaction conditions.Puchol Estors, Victoria, [email protected] ; El Haskouri, Jamal, [email protected] ; Latorre Saborit, Julio, [email protected] ; Beltran Porter, Aurelio, [email protected] ; Beltran Porter, Daniel, [email protected] ; Amoros del Toro, Pedro Jose, [email protected]

Nuevos materiales inorgánicos mediante estrategias de síntesis biomiméticas

Hace cincuenta años que un físico llamado Robert Feynman divisó el principio de la era nanotecnológica, en la que actualmente nos estamos adentrando. Lo que no llegó a imaginar, es hasta que punto se multiplicarían las aplicaciones en el mundo de lo extremadamente pequeño. Microrrobots que navegan por nuestras arterias, ordenadores del tamaño de una mota de polvo, materiales con propiedades extraordinarias e incluso algunos sistemas para eliminar residuos, son algunos de los prodigios que anuncia esta disciplina. Algunos ejemplos de los nuevos materiales que se podrían obtener gracias a la nanotecnología podrían ser: nanotubos de carbono para el desarrollo de células o pilas de combustible capaces de acumular hidrógeno, materiales nanomagnéticos para purificar o incluso desalinizar el agua , encapsulación de alimentos para enmascarar el sabor de alimentos amargos o añadir características deseables en los alimentos tradicionales…aunque quizás las aplicaciones más impactantes e inminentes sean las biomédicas como por ejemplo nanopartículas transportadoras de fármacos capaces de liberar el fármaco poco a poco solamente en las zonas dañadas y moléculas fluorescentes para diagnóstico celular, son algunas de las aplicaciones más inminentes en esta área. Una de las claves para el desarrollo de la Nanotecnología, según Mark Hildreband, es la capacidad de hacer estructuras tridimensionales complejas y a escala nanométrica, que además sean de bajo coste y se puedan sintetizar a gran escala. Un fenómeno extendido en la naturaleza es la formación de minerales bajo el control de un organismo (BIOMINERALIZACIÓN). La Biomineralización estudia la extracción selectiva y la captura de los elementos del medio local y su incorporación a estructuras funcionales bajo un control biológico estricto. En la presente tesis nos centraremos en el estudio del proceso de biomineralización de la sílice y más en concreto en el proceso de silicificación que ocurre en las diatomeas ya que a partir del estudio del caparazón de las mismas se han podido realizar diversas estrategias bioinspiradas empleando agentes directores de estructura que sean capaces de dirigir la organización de la materia, ya sea a nivel bidimensional o tridimensional.Dada la necesidad existente de obtener nuevos materiales multifuncionales para emplearlos en aplicaciones tan diversas como biomédicas, medioambientales y para almacenamiento de datos o de energía, la temática del presente proyecto consistirá principalmente en la obtención de materiales nanoparticulados multifuncionales empleando estrategias de Química dulce o Química suave (“chemie douce” o “soft-chemistry”) como pueden ser reacciones de autoensamblaje empleando surfactantes u otro tipo de sustancias anfifilicas, nuevas rutas de síntesis biomiméticas y bioinspiradas, es decir, a presión y temperatura ambiente, en condiciones diluidas y a pH neutro y por otro lado en la nanofabricación de nuevos materiales mesoporosos ordenados basados en el uso de templates biológicos. Los materiales obtenidos se aplicaran posteriormente para eliminación selectiva de metales de las aguas residuales industriales, en plantas depuradoras para tratamientos iniciales del agua residual de uso doméstico, para mejorar las propiedades de polímeros que puros tienen el inconveniente que arden con facilidad y formando composites con óxidos inorgánicos actuarían como retardantes del fuego y como nanocomposites, ya que por ejemplo la resistencia y dureza de los metales y de las aleaciones metálicas se pueden aumentar mediante la dispersión uniforme de finas partículas de material duro e inerte

El Servicio de Obtención de documentos en las bibliotecas virtuales: Nuevas oportunidades en la gestión de Documentos=Conocimiento.

Virtual libraries are great managers of the knowledge. Document Delivery Services (DDS) facilitate the access to a part of the “explicit knowledge”. The electronic application of the new information´s technologies, formats and the consortial purchases of the collections, give new opportunities for their development. Recent, national and international Literature is reviewed to analyze the impact of the Virtual Libraries in the transformation of the DDS. The conclusion is that a redefinition of DDS is taking place, as part of the rationalization of collection development, the acquisition of electronic publications and retrospective digitalization

¿Que utilizan nuestros usuarios investigadores hospitalarios? Evaluación de la colección en cuatro bibliotecas hospitalarias basado en el análisis de citas bibliográficas de la producción científica de una especialidad médica

INTRODUCTION: The increase of the scientific production, the price of the journal subscriptions and the volume of the consortia puchases along the last years, has made unavoidable the optimization of the management of the collections. Libraries carry out a continuous evaluation of their collection in order to build a basic and strong one that satisfies the needs of the users, thus achieving a balance between utility, quality and price. As a complement to other usage evaluation methods, some libraries are using the analysis of bibliographical citations of the scientific production of their users-researchers. REVISION-OBJECTIVE-HYPOTHESIS: We carried out a complete bibliographical revision on the analysis of citations as a method for the evaluation of the usage of the collections. Then we established the hypothesis that it was a good indicator to know the relevancy of the collection. We evaluated the collection of four libraries. METHODOLOGY: We looked for the scientific production of the Service of Neurology in 2006 in the most important databases. We analyzed the citations and their distribution and frequency, their presence in our collections (both individual and that of the consortium), of the rest of Spain and of outside of Spain, as well as their correlation. RESULTS AND CONCLUSIONS: Our last 10-year collections, both individual and consortium, satisfy more than 77% of the bibliographical citations used in the scientific production of our users. The citation analysis can be an effective tool to evaluate our collections at the present time so much as the basic collections that we keep

Las fuerzas de la colección de publicaciones periodicas de cuatro bibliotecas hospitalarias: análisis del servicio de obtención de documentos

Strengths of the periodic publication collections of four hospital libraries: analysis of the Document Delivery Service. Absctract:The collection development has the main objective of satisfying the community needs by creating base and strengthened collections on the long range, which complement other resources outside the Library. Nowadays, electronic formats and consortial buying have made it easier to access to more information and services and have also homogenized the collections due to the unified buying of the serial packages. We have also assisted to dramatic changes in the users’ habits in the sense they look up an ever more abundant and multidisciplinary information, a fact that we can attribute, at least partially, to an easier access to the bibliographic funds, despite in some cases only as a bibliographic reference. To gather all the information the users demand we must make a strategic planning at least in two perspectives: the development of a basic good quality collection for our own users and also the development of an attractive and necessary collection for the whole libraries community. The general objective of the present study is to find out which are the strengths of our serial collections for external libraries, both in the sense of the titles and subjects that other libraries request and of the temporal period of reference. To achieve this, we have analyzed the document supply requests performed by external users in four hospital Libraries in Madrid (Spain). These data will give us information about the external strengths of our collections, both for our own consortium and for the other libraries. Knowing the strengths of our collections can help us to maintain a cost balance between the resources supplied and requested from our Library through the Document Delivery Service; besides, it can lead to a cost reduction due to the optimization of the utilization of the existing resources with satisfaction of a high proportion of the total demand. Policies for the development of library collections and of the Document Delivery Service should be coordinated in order to achieve a delicate balance between resources that can be acquired in property and those that can be easily and cheaply accessed. All the libraries included in the consortium must assume and implement these policies, both for the development of their own collections and for the interlibrary loans. This strategic policy can lead to an increase of the collections and also to an expansion of the interlibrary agreements that allow diversification of these collections

Pautas para la formulación de una política de gestión de la colección en bibliotecas de ciencias de la salud hospitalaria

The concept of collection has evolved throughout history due to the change in libraries´s mision and objetives. These changes produce a transformation in the philosophy of collection management as this is not only constructed to meet the needs of the hospital community (research, teaching and clinic), but also must be focused on the efficiency of its continued use. The collection management in the current Information Society encompasses all activities necessary to provide access to Health Sciences resources and information. The objetive is to establish the necessary guidelines for the development of a proper collection management policy or program for a hospital’s health sciences library in order to meet the current resources and contents needs of the library’s institutinal users in the Digital Age. The method is a comprehensive literature review and study of developed collection management policies and programs we established guidelines, that were subject to debate and discussion in the working group formed by four health science information professionals librarians. The results is the preparation of guidelines for the formulation of a collection management policy of the health science hospital library. This policy included as base: the guidelines formulated by the American Library Association in 1977, the division established by Clayton and Gordman in 2001 of two different statements within its structure in terms of management and collection development, and the standards necessary to adapt the objectives of the library, users, and the institution to the current requirements of digital content and resources. And the conclusions are that our collections and their management has changed and we need to adapt the collation management policies to the new requirements and targets. The collection management policy is the primary tool to build, guide and maintain appropriate and coherent collections, to sets the standart strategy to follow for the advancement of health science hospital libraries and their integration into the healthcare context

The impact of the electronic journals access on the inter-library loan of the hospital libraries: Analysis of four health sciences libraries

During the year 2003, the Health Sciences libraries of the Clínico San Carlos, La Paz, Móstoles and Ramón y Cajal Hospitals have participated in the consortial purchase of electronic journals that conform the electronic journal collection of the “Virtual Library Laín Entralgo”. Until 2002 the electronic format in our libraries was subordinated to those journals that gave away free electronic access with the paper subscription. Only Móstoles Hospital subscribed to ProQuest Medical Journal aggregator in 2002. OBJECTIVE To analyse the impact of the access to the electronic journals on the interlibrary loan of the four health sciences libraries, comparing the results of the different years and their relation to the consortial libraries. METHODS We have analysed the specific characteristics of each library in terms of volume and antiquity of collection, total volume of interlibrary loans and the loan volume between the consortial libraries, all these in values of requests and deliveries in the last three years. RESULTS Due to the consortial purchase, the libraries’ collections have shown an important increase in size, greater in those libraries with smaller initital collections. The total number of deliveries and requests of documents has decreased, this reduction being more significant between the years 2001 and 2002, and milder with tendency to stabilize in the year 2003. Of the total volume of the Interlibrary loan, more than 73% (2001) is effected within the libraries in the consortium and during these years it has also decreased mildly (62% in 2002 and 60% in 2003). The smaller the library collection, the more requests are made to the consortial libraries and the bigger the library collection, the more deliveries are effected. CONCLUSION During the last three years, our interlibrary loan borrowing volume has decreased, the reduction having seen stronger in 2002 than in 2003. This result is due to some consortial libraries subscribing to electronic journals aggregator in 2001, to the impact of free access to electronic journals through promotional access and the access through unconventional (pirate) methods to electronic journals. In 2003, the interlibrary loan decreased in the consortial libraries due to shared electronic collection

The Ilopango Tierra Blanca Joven (TBJ) eruption, El Salvador: volcano-stratigraphy of a major Holocene event of Central America and hazards implications

The Ilopango caldera, a 11x17 km volcano-tectonic structure filled by an intracalderic lake, is located in El Salvador, and is one of the active volcanoes of the Central American Volcanic Arc, which in turn forms part of the Pacific Ring of Fire. Four large explosive eruptions were recognised during the last 36,000 years: TB4, TB3, TB2 and TBJ that correspond to the last phases of formation of the caldera. Pyroclastic and ash flows from these eruptions cover large areas of the central zone of the country, where it is located the capital San Salvador, a densely populated city and the most important economic centre of El Salvador. The TBJ (Tierra Blanca Joven-Young White Earth) eruption occurred about 1500 years ago, between 430 and 535 AD, with an estimated emission volume of at least 80 km3 of magma. The TBJ eruptive products covered enormous areas that surpassed the present territory of El Salvador. The TBJ unit, of dacitic composition, is characterised by a bright/white color. The eruptive sequence is made of several sub-units. Few cm of fallout deposits, found mainly close to the Ilopango caldera, represent the beginning of the eruption. Subsequently, dense and dilute PDCs of hydromagmatic and magmatic origin filled the depressions near the Ilopango lake with thicknesses of up to at least 70 m and reached distances of at least 40-50 km from the vent, covering completely what today is the actual city of San Salvador. Ash deposits of the last stage of the eruption were found along the whole El Salvador with significant thicknesses. Deposits related to this last phase were reported as well in Guatemala, Honduras, Nicaragua, Costa Rica and the Pacific Ocean. The TBJ eruption was one of the greatest Quaternary eruptions of Central America, where its large eruptive products, considerably affected the Mayan populations living in Salvadoran and near territories at that time. Therefore, a complete study of this eruption was carried out to help in the understanding its evolution and related hazards and posible future impact over the population of El Salvador and nearby countries.This study was financed by CONACYT-CB grant 240447 and logistically supported by MARN-El Salvador.Peer reviewe

The Ilopango Tierra Blanca Joven (TBJ) eruption, El Salvador: Volcano-stratigraphy and physical characterization of the major Holocene event of Central America

The Ilopango caldera is the source of the large Tierra Blanca Joven (TBJ) eruption that occurred about 1.5 ka years ago, between ca. AD270 and AD535. The eruption dispersed volcanic ash over much of the present territory of El Salvador, and pyroclastic density currents (PDCs) extended 40 km from the volcano. In this study, we document the physical characteristics of the deposits from all over El Salvador to further constrain the eruption processes and the intensity and magnitude of the different phases of the eruption. The succession of deposits generated by the TBJ eruption is made of 8 units. The eruption started with PDCs of hydromagmatic origin (Unit A 0 ), followed by fallout deposits (Units A and B) that are <15 cm thick and exposed in sections close to the Ilopango caldera (within 10–15 km). The eruption, then, transitioned into a regime that generated further PDCs (Units C–F), these range from dilute to dense and they filled the depressions near the Ilopango caldera with thicknesses up to 70 m. Deposits from the co-ignimbrite plume (Unit G) are the most widespread, the deposits are found in Guatemala, Honduras, Nicaragua, Costa Rica and the Pacific Ocean and cm-thick across El Salvador. Modelling of the deposits suggests that column heights were 29 km and 7 km for the first two fallout phases, and that the co-ignimbrite phoenix plume rose up to 49 km. Volumes estimated for the fallout units are 0.15, 0.8 and 16 km 3 dense rock equivalent (DRE) for Unit A, B and G respectively. The PDCs deposits volumes were estimated to be ~0.5, ~3.3, ~0.3 and ~9.1 km 3 DRE for Units C, D, E and F, respectively. The combined volume of TBJ deposits is ~30 km 3 DRE (~58 km 3 bulk rock), indicating that it was one of largest Holocene eruptions from Central America. This eruption occurred while Mayan populations were living in the region and it would have had a significant impact on the areas within tens of kilometres of the vent for many years to decades after the eruption. © 2019 Elsevier B.V.This study was financed by CONACYT-CB grant 240447 to GJAD and logistically supported by MARN-El Salvador and PNC-El Salvador.Peer reviewe

The magnitude and impact of the 431 CE Tierra Blanca Joven eruption of Ilopango, El Salvador

The Tierra Blanca Joven (TBJ) eruption from Ilopango volcano deposited thick ash over much of El Salvador when it was inhabited by the Maya, and rendered all areas within at least 80 km of the volcano uninhabitable for years to decades after the eruption. Nonetheless, the more widespread environmental and climatic impacts of this large eruption are not well known because the eruption magnitude and date are not well constrained. In this multifaceted study we have resolved the date of the eruption to 431 ± 2 CE by identifying the ash layer in a well-dated, high-resolution Greenland ice-core record that is >7,000 km from Ilopango; and calculated that between 37 and 82 km3 of magma was dispersed from an eruption coignimbrite column that rose to ∼45 km by modeling the deposit thickness using state-of-the-art tephra dispersal methods. Sulfate records from an array of ice cores suggest stratospheric injection of 14 ± 2 Tg S associated with the TBJ eruption, exceeding those of the historic eruption of Pinatubo in 1991. Based on these estimates it is likely that the TBJ eruption produced a cooling of around 0.5 °C for a few years after the eruption. The modeled dispersal and higher sulfate concentrations recorded in Antarctic ice cores imply that the cooling would have been more pronounced in the Southern Hemisphere. The new date confirms the eruption occurred within the Early Classic phase when Maya expanded across Central America