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Search Results: 1 - 10 of 204816 matches for " Ramón Torrecillas "
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Synthesis and Antimicrobial Activity of a Silver-Hydroxyapatite Nanocomposite
Marcos Díaz,Flora Barba,Miriam Miranda,Francisco Guitián,Ramón Torrecillas,José S. Moya
Journal of Nanomaterials , 2009, DOI: 10.1155/2009/498505
Abstract: A silver-hydroxyapatite nanocomposite has been obtained by a colloidal chemical route and subsequent reduction process in H2/Ar atmosphere at 350°C. This material has been characterized by TEM, XRD, and UV-Visible spectroscopy, showing the silver nanoparticles (~65 nm) supported onto the HA particles (~130 nm) surface without a high degree of agglomeration. The bactericidal effect against common Gram-positive and Gram-negative bacteria has been also investigated. The results indicated a high antimicrobial activity for Staphylococcus aureus, Pneumococcus and Escherichia coli, so this material can be a promising antimicrobial biomaterial for implant and reconstructive surgery applications.
Glass-(nAg, nCu) Biocide Coatings on Ceramic Oxide Substrates
Leticia Esteban-Tejeda, Francisco Malpartida, Luis Antonio Díaz, Ramón Torrecillas, Fernando Rojo, José Serafín Moya
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0033135
Abstract: The present work was focused on obtaining biocide coatings constituted by a glassy soda-lime matrix containing silver or copper nanoparticles on ceramic (alumina and zirconia based) substrates. Both glassy coatings showed a high biocide activity against Gram?, Gram+ bacteria and yeast, reducing cell numbers more than three logarithms. Silver nanoparticles had a significantly higher biocide activity than copper nanoparticles, since the lixiviation levels required to reduce cell numbers more than 3 logarithms was of almost 1–2 μg/cm2 in the case of silver nanoparticles, and 10–15 μg/cm2 for the copper nanoparticles.
Lithium aluminosilicate reinforced with carbon nanofiber and alumina for controlled-thermal-expansion materials
Amparo Borrell, Olga García-Moreno, Ramón Torrecillas, Victoria García-Rocha and Adolfo Fernández
Science and Technology of Advanced Materials , 2012,
Abstract: Materials with a very low or tailored thermal expansion have many applications ranging from cookware to the aerospace industry. Among others, lithium aluminosilicates (LAS) are the most studied family with low and negative thermal expansion coefficients. However, LAS materials are electrical insulators and have poor mechanical properties. Nanocomposites using LAS as a matrix are promising in many applications where special properties are achieved by the addition of one or two more phases. The main scope of this work is to study the sinterability of carbon nanofiber (CNFs)/LAS and CNFs/alumina/LAS nanocomposites, and to adjust the ratio among components for obtaining a near-zero or tailored thermal expansion. Spark plasma sintering of nanocomposites, consisting of commercial CNFs and alumina powders and an ad hoc synthesized β-eucryptite phase, is proposed as a solution to improving mechanical and electrical properties compared with the LAS ceramics obtained under the same conditions. X-ray diffraction results on phase compositions and microstructure are discussed together with dilatometry data obtained in a wide temperature range ( 150 to 450 °C). The use of a ceramic LAS phase makes it possible to design a nanocomposite with a very low or tailored thermal expansion coefficient and exceptional electrical and mechanical properties.
Bone Loss at Implant with Titanium Abutments Coated by Soda Lime Glass Containing Silver Nanoparticles: A Histological Study in the Dog
Arturo Martinez, Francisco Guitián, Roberto López-Píriz, José F. Bartolomé, Belén Cabal, Leticia Esteban-Tejeda, Ramón Torrecillas, José S. Moya
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0086926
Abstract: The aim of the present study was to evaluate bone loss at implants connected to abutments coated with a soda-lime glass containing silver nanoparticles, subjected to experimental peri-implantitis. Also the aging and erosion of the coating in mouth was studied. Five beagle dogs were used in the experiments. Three implants were placed in each mandible quadrant: in 2 of them, Glass/n-Ag coated abutments were connected to implant platform, 1 was covered with a Ti-mechanized abutment. Experimental peri-implantitis was induced in all implants after the submarginal placement of cotton ligatures, and three months after animals were euthanatized. Thickness and morphology of coating was studied in abutment cross-sections by SEM. Histology and histo-morphometric studies were carried on in undecalfied ground slides. After the induced peri-implantitis: 1.The abutment coating shown losing of thickness and cracking. 2. The histometry showed a significant less bone loss in the implants with glass/n-Ag coated abutments. A more symmetric cone of bone resorption was observed in the coated group. There were no significant differences in the peri-implantitis histological characteristics between both groups of implants. Within the limits of this in-vivo study, it could be affirmed that abutments coated with biocide soda-lime-glass-silver nanoparticles can reduce bone loss in experimental peri-implantitis. This achievement makes this coating a suggestive material to control peri-implantitis development and progression.
Inhibitory Effect on In Vitro Streptococcus oralis Biofilm of a Soda-Lime Glass Containing Silver Nanoparticles Coating on Titanium Alloy
Belén Cabal, Fabio Cafini, Leticia Esteban-Tejeda, Luís Alou, José F. Bartolomé, David Sevillano, Roberto López-Piriz, Ramón Torrecillas, José Serafín Moya
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0042393
Abstract: This paper reports the effect of soda-lime-glass-nAg coating on the viability of an in vitro biofilm of Streptococcus oralis. Three strains (ATCC 35037 and two clinical isolates from periodontitis patients) were grown on coated with glass, glass containing silver nanoparticles, and uncoated titanium alloy disks. Two different methods were used to quantify biofilm formation abilities: crystal violet staining and determination of viable counts. The influence of the surface morphology on the cell attachment was studied. The surface morphology was characterized by scanning electron microscopy (SEM) and using a profilometer. SEM was also used to study the formation and the development of biofilm on the coated and uncoated disks. At least a >99.7% inocula reduction of biofilm respect to titanium disks and also to glass coated disks was observed in the glass-nAg coated disks for all the studied strains. A quantitative evaluation of the release of silver was conducted in vitro to test whether and to what extend the biocidal agent (silver) could leach from the coating. These findings suggest that the biofilm formation of S. oralis strains is highly inhibited by the glass-nAg and may be useful for materials which require durable antibacterial effect on their surfaces, as it is the case of dental implants.
Radiologic Evaluation of Bone Loss at Implants with Biocide Coated Titanium Abutments: A Study in the Dog
Roberto López-Píriz, Eva Solá-Linares, Juan J. Granizo, Idohia Díaz-Güemes, Silvia Enciso, José F. Bartolomé, Belén Cabal, Leticia Esteban-Tejeda, Ramón Torrecillas, José S. Moya
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0052861
Abstract: The objective of the present study is to evaluate bone loss at implant abutments coated with a soda-lime glass containing silver nanoparticles subjected to experimental peri-implantitis. Five beagle dogs were used in the experiments, 3 implants were installed in each quadrant of the mandibles. Glass/n-Ag coted abutments were connected to implant platform. Cotton floss ligatures were placed in a submarginal position around the abutment necks and the animals were subject to a diet which allowed plaque accumulation, and after 15 weeks the dogs were sacrificed. Radiographs of all implant sites were obtained at the beginning and at the end of the experimentally induced peri-implantitis. The radiographic examination indicated that significant amounts of additional bone loss occurred in implants without biocide coating, considering both absolute and relative values of bone loss. Percentages of additional bone loss observed in implants dressed with a biocide coated abutment were about 3 times lower (p<0.006 distal aspect; and p<0.031 at mesial aspect) than the control ones. Within the limits of the present study it seems promising the use of soda-lime glass/nAg coatings on abutments to prevent peri-implant diseases.
Atomical Grothendieck categories
C. N st sescu,B. Torrecillas
International Journal of Mathematics and Mathematical Sciences , 2003, DOI: 10.1155/s0161171203209418
Abstract: Motivated by the study of Gabriel dimension of a Grothendieck category, we introduce the concept of atomical Grothendieck category, which has only two localizing subcategories, and we give a classification of this type of Grothendieck categories.
Long-Term Effects of Irrigation with Waste Water on Soil AM Fungi Diversity and Microbial Activities: The Implications for Agro-Ecosystem Resilience
Maria del Mar Alguacil, Emma Torrecillas, Pilar Torres, Fuensanta García-Orenes, Antonio Roldán
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0047680
Abstract: The effects of irrigation with treated urban wastewater (WW) on the arbuscular mycorrhizal fungi (AMF) diversity and soil microbial activities were assayed on a long-term basis in a semiarid orange-tree orchard. After 43 years, the soil irrigated with fresh water (FW) had higher AMF diversity than soils irrigated with WW. Microbial activities were significantly higher in the soils irrigated with WW than in those irrigated with FW. Therefore, as no negative effects were observed on crop vitality and productivity, it seems that the ecosystem resilience gave rise to the selection of AMF species better able to thrive in soils with higher microbial activity and, thus, to higher soil fertility.
Changes in the Diversity of Soil Arbuscular Mycorrhizal Fungi after Cultivation for Biofuel Production in a Guantanamo (Cuba) Tropical System
Maria del Mar Alguacil, Emma Torrecillas, Guillermina Hernández, Antonio Roldán
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0034887
Abstract: The arbuscular mycorrhizal fungi (AMF) are a key, integral component of the stability, sustainability and functioning of ecosystems. In this study, we characterised the AMF biodiversity in a native vegetation soil and in a soil cultivated with Jatropha curcas or Ricinus communis, in a tropical system in Guantanamo (Cuba), in order to verify if a change of land use to biofuel plant production had any effect on the AMF communities. We also asses whether some soil properties related with the soil fertility (total N, Organic C, microbial biomass C, aggregate stability percentage, pH and electrical conductivity) were changed with the cultivation of both crop species. The AM fungal small sub-unit (SSU) rRNA genes were subjected to PCR, cloning, sequencing and phylogenetic analyses. Twenty AM fungal sequence types were identified: 19 belong to the Glomeraceae and one to the Paraglomeraceae. Two AMF sequence types related to cultured AMF species (Glo G3 for Glomus sinuosum and Glo G6 for Glomus intraradices-G. fasciculatum-G. irregulare) did not occur in the soil cultivated with J. curcas and R. communis. The soil properties (total N, Organic C and microbial biomass C) were higher in the soil cultivated with the two plant species. The diversity of the AMF community decreased in the soil of both crops, with respect to the native vegetation soil, and varied significantly depending on the crop species planted. Thus, R. communis soil showed higher AMF diversity than J. curcas soil. In conclusion, R. communis could be more suitable for the long-term conservation and sustainable management of these tropical ecosytems.
La investigación arquitectónica, el proyecto de arquitectura y el acondicionamiento ambiental en el proyecto de adecuación de la planta principal del Palacio de Carlos V de Granada
Jiménez Torrecillas, A,Sendra, Juan J,Torices, N,Mu?oz, O
Informes de la Construccion , 2007,
Abstract: The Charles V Palace is located in the Complex of Monuments of the Alhambra in Granada; despite the fact that it appears to be a fi nished building according to the design by Pedro Machuca, actually it was never completed. It is a clear example of what modern history writers would term a a longdurationa building. Its main fl oor currently houses the Fine Arts Museum of Granada. The proposal to install this museum here was put forward in the 1940s, after the palace was completed in 1928 by Torres Balbás. The project was implemented by F. Prieto Moreno and the museum was opened in 1958. In 2000, the project to adapt the main fl oor of the Charles V Palace was drawn up. This project has already been implemented, although the museum project is expected to be completed in 2007. Based on architectural research, the abovementioned project includes environmental conditioning of the palace rooms, especially light, hygrothermal and air quality conditioning, as well as the installations required for exposition purposes, which mainly guarantee the visual observation of the works of art on display, conservation conditions of these works, visitorsa comfort and energy effi ciency. This article details the respectful way in which this adaptation project is meeting those objectives. El Palacio de Carlos V, situado en el Conjunto Monumental de la Alhambra de Granada, a pesar de su apariencia de edifi cio concluido de acuerdo a un proyecto, el de Pedro Machuca, no llegó a ser ejecutado en su totalidad. Constituye un claro ejemplo de lo que la historiografía moderna denominaría como edifi cio sujeto a a larga duracióna . Su planta principal acoge en la actualidad el Museo de Bellas Artes de Granada. Tras el proyecto de terminación del Palacio realizado por Torres Balbás en 1928, la idea de instalar dicho museo se produce en la década de 1940, con un proyecto realizado por F. Prieto Moreno e inaugurado en 1958. En el a o 2000 se redacta el Proyecto de Adecuación de la Planta Principal del Palacio de Carlos V. Ese proyecto está ya ejecutado, aunque el proyecto museográfi co tiene previsto su fi nalización en 2007. El citado proyecto de adecuación aborda, desde la investigación arquitectónica, el acondicionamiento ambiental de las salas del palacio, especialmente el lumínico, el higrotérmico y el de calidad del aire, así como la inclusión de las instalaciones necesarias acordes al uso expositivo, que garanticen principalmente la contemplación visual de las obras expuestas, las condiciones de conservación de esas obras, el confort de los visitantes y la efi ciencia ener
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