Angel Valenzuela - Academia.edu (original) (raw)

Papers by Angel Valenzuela

Es parte de nuestra actualidad que los estudiantes noveles de la educacion superior llegan a Ia u... more Es parte de nuestra actualidad que los estudiantes noveles de la educacion superior llegan a Ia universidad con importantes necesidades en el ambito de la comunicacion, aspecto clave para ayudarlos a adquirir buena parte de las competencias que necesitaran en el mundo labora]. De este modo, el Programa de Formacion Fundamental de la Universidad de Talca, pondera el nuevo contexto que subyace a nuestro sistema de educacion actual: los cambios en el sistema de ingreso a la educacion superior (heterogenizacion de las aulas) y la democratizacion de la ensenanza. Con el fin de responder a esto, el curso de Comunicacion oral y escrita, perteneciente al programa mencionado, tiene durante todo el primer ano la mision de insertar por medio del desarrollo de competencias comunicativas a los estudiantes de primer ano en una comunidad linguistica academica y profesional. Por lo anterior, esta investigacion tiene por objetivo difundir Ias experiencias sobre el trabajo en el desarrollo de estrate...

Journal of the Mexican Chemical Society, 2019

The photocatalytic reduction of benzophenone was studied focusing on improving the yield to benzh... more The photocatalytic reduction of benzophenone was studied focusing on improving the yield to benzhydrol. TiO2 was synthesized by means of a hydrothermal technique. TiO2 (Degussa TiO2-P25) was used as a reference. Catalysts were characterized by XRD and nitrogen physisorption. The photocatalytic reduction was carried out in a batch reactor at 25 °C under nitrogen atmosphere, acetonitrile as solvent and isopropanol as electron donor. A 200 W Xe-Hg lamp (λ= 360 nm) was employed as irradiation source. The chemical composition of the reaction system was determined by HPLC. Structural and textural properties of the synthesized TiO2 depended on the type of acid used during sol formation step. Using HCl, a higher specific surface area and narrower pore size distribution of TiO2 was obtained in comparison with acetic acid. As expected, the photochemical reduction of benzophenone yielded benzopinacol as main product, whereas, benzhydrol is only produced in presence of TiO2 (i.e. photocatalytic...

Literatura y Lingüística, 2018

La producción científica a través de la publicación de artículos se ha convertido en un criterio ... more La producción científica a través de la publicación de artículos se ha convertido en un criterio de validación y cualificación investigativa en la formación de capital humano avanzado. Por esto, el objetivo del presente estudio fue analizar la producción científica en el área de la lingüística, particularmente la generada por los egresados de doctorado financiados por el programa de becas de Chile. En cuanto a la metodología, se contempló como unidad de análisis las publicaciones realizadas por los becarios cuyo egreso estuvo entre los años 2008 y 2015. Los resultados indican que las dinámicas de la producción científica son relativamente estables, produciéndose alzas al finalizar el proceso de formación doctoral.

Journal of Lightwave Technology, 2015

This study presents a computer program as a tool for the harmonic analysis of multi-phase electri... more This study presents a computer program as a tool for the harmonic analysis of multi-phase electric power distribution systems. In the program, the source of harmonics can be any number of multi-phase harmonic currents and/or voltages, or up to 10 three-phase converters. Frequency dependent models of ac network elements are assembled into a sparse admittance matrix. Then sparsity techniques are employed to determine the current flow in all elements and voltages at all busses throughout the system at any harmonic frequency up to 3 KHz. Voltage distortion factors that represent the overall effects of the harmonics on the system voltages are also calculated.

Journal of Optical Technology, 2002

This paper discusses features of the transmission of light along a symmetric Y-shaped waveguide o... more This paper discusses features of the transmission of light along a symmetric Y-shaped waveguide operating as a 1ϫ2 optical splitter. A detailed description is given of the design of the splitter. Using the Fourier ray approximation method, the effect of three factors on the splitting coefficient of the output energy is numerically analyzed: the length of the input waveguide and the transverse displacement and tilt angle of the input beam.

Optical Materials, 2013

Optical waveguides have been obtained by silver ion implantation on fused silica substrates. Silv... more Optical waveguides have been obtained by silver ion implantation on fused silica substrates. Silver ion implantation profiles were calculated in a SiO 2 matrix with different energies of implantation from 125 keV to 10 MeV. Refractive index change (Dn) of the ion implanted waveguides was calculated as a function of their chemical composition. Optical absorption spectra of waveguides obtained by 9 MeV silver ion implantation, at a dose of 5 Â 10 16 ions/cm 2 , exhibit the typical absorption band associated to the surface plasmon resonance of silver nanoparticles. Effective refractive indices of the propagation modes and waveguide propagation losses of silver ion implanted waveguides are also presented.

Journal of Clinical Pathology, 1993

Aztreonam agar is especially useful in the primary isolation of S aureus from the sputum of patie... more Aztreonam agar is especially useful in the primary isolation of S aureus from the sputum of patients with cystic fibrosis and is now part of our standard protocol for such patients. We thank Gillian Aggasild, Dennis Golder, and Sheila Mackay and all the other MLSOs for their help with this study. 1 Hill JH, White EC. Sodium chloride media for the separation of certain Gram positive cocci and Gram negative bacilli. JBacteriol 1929;18:43-57. 2 Barker M, Kuper SWA. Identification of Staphylococcus pyogenes by the phosphatase reaction.

Human Immunology, 2003

To investigate the possible role of the polymorphism located in the regulatory region of monocyte... more To investigate the possible role of the polymorphism located in the regulatory region of monocyte chemoattractant protein-1 (MCP-1) gene in the susceptibility to rheumatoid arthritis (RA), a total of 141 Spanish RA patients and 194 controls, previously typed for human leukocyte antigen DRB1* (HLA-DRB1*), were genotyped for-2518 (A/G) MCP-1 gene polymorphism using polymerase chain reaction-restriction fragment length polymorphism. No association between-2518 (A/G) MCP-1 polymorphism and susceptibility to RA was found. Nevertheless, when patients and controls were stratified according to their HLA shared epitope (SE) status, a significant increase in the frequency of genotype GG was found among SE negative (SEϪ) patients with respect to both SE positive (SEϩ) patients and SEϪ controls (16% versus 4% in SEϩ patients, p Fisher ϭ 0.04, odds ratio [OR] ϭ 4.4, 95% confidence interval [95%CI] ϭ 1.03-21.48; and 4% in SEϪ controls, p Fisher ϭ 0.02, OR ϭ 4.13, 95%CI ϭ 1.10-15.72). In conclusion, MCP-1 polymorphism is slightly associated with the susceptibility to RA in patients lacking the HLA SE.

This article is the result of a research conducted during the first half of 2013. The question wa... more This article is the result of a research conducted during the first half of 2013. The question was to know under what conditions our students enter the university in relation to their com- munication skills in foreign languages. This motivated developing, in the first place, six sur- veys, in order to obtain the students’ perception regarding those skills developed during their school period, i.e. listening comprehension, reading comprehension, oral communication and written communication. First, the results are presented in terms of percentage regarding the students’ perception of their level of development of the skills mentioned above. Then, each of the skills and their content are mentioned and also quantified in percentages. Finally, the less developed skills and activities are summarized, those having exclusively less than 50% of perception development.

J Phys Chem Solids, 2011

MgAl layered double hydroxides (MgAl LDH) were synthesized by the sol-gel method using ultrasound... more MgAl layered double hydroxides (MgAl LDH) were synthesized by the sol-gel method using ultrasound irradiation in the crystallization step. The interlayer anions were nitrate and acetylacetonate-ethoxide. The solids were characterized by XRD, N 2-physisorption and TEM. TiO 2 /MgAl LDH mixtures were prepared by mixing the MgAl LDH (as prepared) or the calcined sample with TiO 2 (Aldrich, 99.9% anatase) in different weight ratios. Photocatalytic activities of the TiO 2 /MgAl LDH mixtures were evaluated through the degradation of phenol as model pollutant. TiO 2 /MgAl LDH mixture (1:1) was more photocatalytically active for the degradation of phenol than pure TiO 2. The synergy effect was attributed to a higher production of OH radicals, which were formed from the structural hydroxides. Also, the hydrotalcite phase enhanced the phenol adsorption and transfer to the TiO 2 sites where the phenol was photocatalytically degradated.

Journal of Porous Materials, 2009

Silicalite-1 crystals were synthesized from clear and diluted solutions by the dry-gel conversion... more Silicalite-1 crystals were synthesized from clear and diluted solutions by the dry-gel conversion method and the hydrothermal method was used as reference to do a comparative study. The effect of the structuredirecting agent, silica source, aging time and crystallization time was investigated. Zeolite crystals, about 200-500 nm and 1 micron, were obtained by the liquid phase hydrothermal (LPH) and steam-assisted crystallization (SAC), called as dry-gel conversion method, respectively. The crystals were identified by XRD and SEM. The results show that the aging time and the water content are crucial in the synthesis of zeolites. Indeed, well formed zeolite crystals are obtained by the SAC technique using a lower amount of water than in the LPH method. However, the presence of the structure directing agent (SDA) into the dry gel determines the crystallization of silicalite-1.

Revista mexicana de ingeniería química

This paper describes the fabrication and characterization of multimode polymer optical waveguides... more This paper describes the fabrication and characterization of multimode polymer optical waveguides ob- tained using a SU-8-2005 polymer by means of photolithographic process. Critical information about refractive index modulation of polymer waveguides as function of fabrication parameters as pre-baked and ultraviolet exposure times is presented. Physical properties of the waveguides were determined by means prism-coupling technique, optical and SEM microscopy.

Journal of Advanced Oxidation Technologies

Organic synthesis through semiconductor photocatalysis has become an important research area in p... more Organic synthesis through semiconductor photocatalysis has become an important research area in photochemistry in the last two decades. Significant examples of organic transformations employed for synthetic purposes are oxidation and reduction reactions, isomerization reactions, C-H bond activations and C-C and C-N bond forming reactions. In this review, the use of irradiated semiconductors and different operation conditions in the reduction of organic compounds is surveyed. Here, the photocatalytic reduction of nitroarenes, aldehydes, ketones and miscellaneous compounds will be discussed. This review is concluded with some perspectives of our group on the directions toward which future research may be aimed.

Thin Solid Films, 2000

Thin films of SnO2:F deposited by spray pyrolysis over glass substrate at 300°C, were studied by ... more Thin films of SnO2:F deposited by spray pyrolysis over glass substrate at 300°C, were studied by scanning, conventional and high resolution electron microscopy together with atomic force microscopy. The surface topology and morphology changes detected for films deposited with various fluorine levels are related to the electrical behavior previously reported.

Tissue Antigens, 1999

Cytotoxic T-lymphocyte antigen 4 (CTLA4) polymorphisms located in the promotor region at position... more Cytotoxic T-lymphocyte antigen 4 (CTLA4) polymorphisms located in the promotor region at positions -318 (C/T) and in exon 1 (49 A/ G) were investigated in 138 Spanish patients (37 men and 101 women) with rheumatoid arthritis and in 305 ethnically-matched healthy controls. When the allelic and genotypic frequencies corresponding to the CTLA4 -318 position were compared, no significant differences between patients and controls were found. However, when the CTLA4 49 A/G polymorphism was analysed, a significant increase of A/G heterozygous individuals among female patients (48.5% vs. 33.8% in controls; P=0.008; OR=2.0) was observed. This increase was absent among males (37.8%, P=NS). Analysis of the CTLA4 49 polymorphism with respect to HLA-DRB1 typing demonstrated a significant increase of A/G heterozygosity in the HLA-DR3-positive patient group compared with HLA-DR3-negative patient group (14/19, 74% vs. 49/119, 41%; P=0.009, OR=4.0). The increase of A/G genotype among HLA-DR3-positive patients was found in both males (4/6, 67%) and females' (10/13, 77%), although statistical differences were only reached in the female group. These results provide new insight into this complex association, confirm previous data from other studies, and suggest that the CTLA4 gene could be involved in the pathogenesis of rheumatoid arthritis.

Journal of Porous Materials, 2009

Silicalite-1 crystals were synthesized from clear and diluted solutions by the dry-gel conversion... more Silicalite-1 crystals were synthesized from clear and diluted solutions by the dry-gel conversion method and the hydrothermal method was used as reference to do a comparative study. The effect of the structuredirecting agent, silica source, aging time and crystallization time was investigated. Zeolite crystals, about 200-500 nm and 1 micron, were obtained by the liquid phase hydrothermal (LPH) and steam-assisted crystallization (SAC), called as dry-gel conversion method, respectively. The crystals were identified by XRD and SEM. The results show that the aging time and the water content are crucial in the synthesis of zeolites. Indeed, well formed zeolite crystals are obtained by the SAC technique using a lower amount of water than in the LPH method. However, the presence of the structure directing agent (SDA) into the dry gel determines the crystallization of silicalite-1.

European Journal of Immunogenetics, 2008

The presence of certain vitamin D receptor (VDR) genotypes has been associated with low bone mine... more The presence of certain vitamin D receptor (VDR) genotypes has been associated with low bone mineral density (BMD) in elderly populations as well as with accelerated bone loss in patients with rheumatoid arthritis (RA). In the present study, VDR genotypes from 120 Spanish patients with RA were investigated. Three VDR gene polymorphisms (BsmI, ApaI and TaqI) were investigated using polymerase chain reaction followed by enzymatic digestion. The distributions of VDR allelic frequencies were similar in patients and controls and therefore no influence of VDR polymorphisms on rheumatoid arthritis susceptibility could be demonstrated. However, in an analysis of the clinical features of the different VDR-related genetic subgroups, the BB/tt genotype, defined by the BsmI and TaqI restriction site polymorphisms, was identified to be weakly associated with an early onset RA in female patients. This VDR genotype has been associated with a low BMD level in various studies. When patients were stratified according to the presence of the shared HLA epitope SE, it was found that SE + female patients bearing the BB/tt genotype showed the earliest disease onset. The mechanisms by which the VDR polymorphism is associated with RA is unknown, but they could be related to the immunoregulatory properties of vitamin D.

Es parte de nuestra actualidad que los estudiantes noveles de la educacion superior llegan a Ia u... more Es parte de nuestra actualidad que los estudiantes noveles de la educacion superior llegan a Ia universidad con importantes necesidades en el ambito de la comunicacion, aspecto clave para ayudarlos a adquirir buena parte de las competencias que necesitaran en el mundo labora]. De este modo, el Programa de Formacion Fundamental de la Universidad de Talca, pondera el nuevo contexto que subyace a nuestro sistema de educacion actual: los cambios en el sistema de ingreso a la educacion superior (heterogenizacion de las aulas) y la democratizacion de la ensenanza. Con el fin de responder a esto, el curso de Comunicacion oral y escrita, perteneciente al programa mencionado, tiene durante todo el primer ano la mision de insertar por medio del desarrollo de competencias comunicativas a los estudiantes de primer ano en una comunidad linguistica academica y profesional. Por lo anterior, esta investigacion tiene por objetivo difundir Ias experiencias sobre el trabajo en el desarrollo de estrate...

Journal of the Mexican Chemical Society, 2019

The photocatalytic reduction of benzophenone was studied focusing on improving the yield to benzh... more The photocatalytic reduction of benzophenone was studied focusing on improving the yield to benzhydrol. TiO2 was synthesized by means of a hydrothermal technique. TiO2 (Degussa TiO2-P25) was used as a reference. Catalysts were characterized by XRD and nitrogen physisorption. The photocatalytic reduction was carried out in a batch reactor at 25 °C under nitrogen atmosphere, acetonitrile as solvent and isopropanol as electron donor. A 200 W Xe-Hg lamp (λ= 360 nm) was employed as irradiation source. The chemical composition of the reaction system was determined by HPLC. Structural and textural properties of the synthesized TiO2 depended on the type of acid used during sol formation step. Using HCl, a higher specific surface area and narrower pore size distribution of TiO2 was obtained in comparison with acetic acid. As expected, the photochemical reduction of benzophenone yielded benzopinacol as main product, whereas, benzhydrol is only produced in presence of TiO2 (i.e. photocatalytic...

Literatura y Lingüística, 2018

La producción científica a través de la publicación de artículos se ha convertido en un criterio ... more La producción científica a través de la publicación de artículos se ha convertido en un criterio de validación y cualificación investigativa en la formación de capital humano avanzado. Por esto, el objetivo del presente estudio fue analizar la producción científica en el área de la lingüística, particularmente la generada por los egresados de doctorado financiados por el programa de becas de Chile. En cuanto a la metodología, se contempló como unidad de análisis las publicaciones realizadas por los becarios cuyo egreso estuvo entre los años 2008 y 2015. Los resultados indican que las dinámicas de la producción científica son relativamente estables, produciéndose alzas al finalizar el proceso de formación doctoral.

Journal of Lightwave Technology, 2015

This study presents a computer program as a tool for the harmonic analysis of multi-phase electri... more This study presents a computer program as a tool for the harmonic analysis of multi-phase electric power distribution systems. In the program, the source of harmonics can be any number of multi-phase harmonic currents and/or voltages, or up to 10 three-phase converters. Frequency dependent models of ac network elements are assembled into a sparse admittance matrix. Then sparsity techniques are employed to determine the current flow in all elements and voltages at all busses throughout the system at any harmonic frequency up to 3 KHz. Voltage distortion factors that represent the overall effects of the harmonics on the system voltages are also calculated.

Journal of Optical Technology, 2002

This paper discusses features of the transmission of light along a symmetric Y-shaped waveguide o... more This paper discusses features of the transmission of light along a symmetric Y-shaped waveguide operating as a 1ϫ2 optical splitter. A detailed description is given of the design of the splitter. Using the Fourier ray approximation method, the effect of three factors on the splitting coefficient of the output energy is numerically analyzed: the length of the input waveguide and the transverse displacement and tilt angle of the input beam.

Optical Materials, 2013

Optical waveguides have been obtained by silver ion implantation on fused silica substrates. Silv... more Optical waveguides have been obtained by silver ion implantation on fused silica substrates. Silver ion implantation profiles were calculated in a SiO 2 matrix with different energies of implantation from 125 keV to 10 MeV. Refractive index change (Dn) of the ion implanted waveguides was calculated as a function of their chemical composition. Optical absorption spectra of waveguides obtained by 9 MeV silver ion implantation, at a dose of 5 Â 10 16 ions/cm 2 , exhibit the typical absorption band associated to the surface plasmon resonance of silver nanoparticles. Effective refractive indices of the propagation modes and waveguide propagation losses of silver ion implanted waveguides are also presented.

Journal of Clinical Pathology, 1993

Aztreonam agar is especially useful in the primary isolation of S aureus from the sputum of patie... more Aztreonam agar is especially useful in the primary isolation of S aureus from the sputum of patients with cystic fibrosis and is now part of our standard protocol for such patients. We thank Gillian Aggasild, Dennis Golder, and Sheila Mackay and all the other MLSOs for their help with this study. 1 Hill JH, White EC. Sodium chloride media for the separation of certain Gram positive cocci and Gram negative bacilli. JBacteriol 1929;18:43-57. 2 Barker M, Kuper SWA. Identification of Staphylococcus pyogenes by the phosphatase reaction.

Human Immunology, 2003

To investigate the possible role of the polymorphism located in the regulatory region of monocyte... more To investigate the possible role of the polymorphism located in the regulatory region of monocyte chemoattractant protein-1 (MCP-1) gene in the susceptibility to rheumatoid arthritis (RA), a total of 141 Spanish RA patients and 194 controls, previously typed for human leukocyte antigen DRB1* (HLA-DRB1*), were genotyped for-2518 (A/G) MCP-1 gene polymorphism using polymerase chain reaction-restriction fragment length polymorphism. No association between-2518 (A/G) MCP-1 polymorphism and susceptibility to RA was found. Nevertheless, when patients and controls were stratified according to their HLA shared epitope (SE) status, a significant increase in the frequency of genotype GG was found among SE negative (SEϪ) patients with respect to both SE positive (SEϩ) patients and SEϪ controls (16% versus 4% in SEϩ patients, p Fisher ϭ 0.04, odds ratio [OR] ϭ 4.4, 95% confidence interval [95%CI] ϭ 1.03-21.48; and 4% in SEϪ controls, p Fisher ϭ 0.02, OR ϭ 4.13, 95%CI ϭ 1.10-15.72). In conclusion, MCP-1 polymorphism is slightly associated with the susceptibility to RA in patients lacking the HLA SE.

This article is the result of a research conducted during the first half of 2013. The question wa... more This article is the result of a research conducted during the first half of 2013. The question was to know under what conditions our students enter the university in relation to their com- munication skills in foreign languages. This motivated developing, in the first place, six sur- veys, in order to obtain the students’ perception regarding those skills developed during their school period, i.e. listening comprehension, reading comprehension, oral communication and written communication. First, the results are presented in terms of percentage regarding the students’ perception of their level of development of the skills mentioned above. Then, each of the skills and their content are mentioned and also quantified in percentages. Finally, the less developed skills and activities are summarized, those having exclusively less than 50% of perception development.

J Phys Chem Solids, 2011

MgAl layered double hydroxides (MgAl LDH) were synthesized by the sol-gel method using ultrasound... more MgAl layered double hydroxides (MgAl LDH) were synthesized by the sol-gel method using ultrasound irradiation in the crystallization step. The interlayer anions were nitrate and acetylacetonate-ethoxide. The solids were characterized by XRD, N 2-physisorption and TEM. TiO 2 /MgAl LDH mixtures were prepared by mixing the MgAl LDH (as prepared) or the calcined sample with TiO 2 (Aldrich, 99.9% anatase) in different weight ratios. Photocatalytic activities of the TiO 2 /MgAl LDH mixtures were evaluated through the degradation of phenol as model pollutant. TiO 2 /MgAl LDH mixture (1:1) was more photocatalytically active for the degradation of phenol than pure TiO 2. The synergy effect was attributed to a higher production of OH radicals, which were formed from the structural hydroxides. Also, the hydrotalcite phase enhanced the phenol adsorption and transfer to the TiO 2 sites where the phenol was photocatalytically degradated.

Journal of Porous Materials, 2009

Silicalite-1 crystals were synthesized from clear and diluted solutions by the dry-gel conversion... more Silicalite-1 crystals were synthesized from clear and diluted solutions by the dry-gel conversion method and the hydrothermal method was used as reference to do a comparative study. The effect of the structuredirecting agent, silica source, aging time and crystallization time was investigated. Zeolite crystals, about 200-500 nm and 1 micron, were obtained by the liquid phase hydrothermal (LPH) and steam-assisted crystallization (SAC), called as dry-gel conversion method, respectively. The crystals were identified by XRD and SEM. The results show that the aging time and the water content are crucial in the synthesis of zeolites. Indeed, well formed zeolite crystals are obtained by the SAC technique using a lower amount of water than in the LPH method. However, the presence of the structure directing agent (SDA) into the dry gel determines the crystallization of silicalite-1.

Revista mexicana de ingeniería química

This paper describes the fabrication and characterization of multimode polymer optical waveguides... more This paper describes the fabrication and characterization of multimode polymer optical waveguides ob- tained using a SU-8-2005 polymer by means of photolithographic process. Critical information about refractive index modulation of polymer waveguides as function of fabrication parameters as pre-baked and ultraviolet exposure times is presented. Physical properties of the waveguides were determined by means prism-coupling technique, optical and SEM microscopy.

Journal of Advanced Oxidation Technologies

Organic synthesis through semiconductor photocatalysis has become an important research area in p... more Organic synthesis through semiconductor photocatalysis has become an important research area in photochemistry in the last two decades. Significant examples of organic transformations employed for synthetic purposes are oxidation and reduction reactions, isomerization reactions, C-H bond activations and C-C and C-N bond forming reactions. In this review, the use of irradiated semiconductors and different operation conditions in the reduction of organic compounds is surveyed. Here, the photocatalytic reduction of nitroarenes, aldehydes, ketones and miscellaneous compounds will be discussed. This review is concluded with some perspectives of our group on the directions toward which future research may be aimed.

Thin Solid Films, 2000

Thin films of SnO2:F deposited by spray pyrolysis over glass substrate at 300°C, were studied by ... more Thin films of SnO2:F deposited by spray pyrolysis over glass substrate at 300°C, were studied by scanning, conventional and high resolution electron microscopy together with atomic force microscopy. The surface topology and morphology changes detected for films deposited with various fluorine levels are related to the electrical behavior previously reported.

Tissue Antigens, 1999

Cytotoxic T-lymphocyte antigen 4 (CTLA4) polymorphisms located in the promotor region at position... more Cytotoxic T-lymphocyte antigen 4 (CTLA4) polymorphisms located in the promotor region at positions -318 (C/T) and in exon 1 (49 A/ G) were investigated in 138 Spanish patients (37 men and 101 women) with rheumatoid arthritis and in 305 ethnically-matched healthy controls. When the allelic and genotypic frequencies corresponding to the CTLA4 -318 position were compared, no significant differences between patients and controls were found. However, when the CTLA4 49 A/G polymorphism was analysed, a significant increase of A/G heterozygous individuals among female patients (48.5% vs. 33.8% in controls; P=0.008; OR=2.0) was observed. This increase was absent among males (37.8%, P=NS). Analysis of the CTLA4 49 polymorphism with respect to HLA-DRB1 typing demonstrated a significant increase of A/G heterozygosity in the HLA-DR3-positive patient group compared with HLA-DR3-negative patient group (14/19, 74% vs. 49/119, 41%; P=0.009, OR=4.0). The increase of A/G genotype among HLA-DR3-positive patients was found in both males (4/6, 67%) and females' (10/13, 77%), although statistical differences were only reached in the female group. These results provide new insight into this complex association, confirm previous data from other studies, and suggest that the CTLA4 gene could be involved in the pathogenesis of rheumatoid arthritis.

Journal of Porous Materials, 2009

Silicalite-1 crystals were synthesized from clear and diluted solutions by the dry-gel conversion... more Silicalite-1 crystals were synthesized from clear and diluted solutions by the dry-gel conversion method and the hydrothermal method was used as reference to do a comparative study. The effect of the structuredirecting agent, silica source, aging time and crystallization time was investigated. Zeolite crystals, about 200-500 nm and 1 micron, were obtained by the liquid phase hydrothermal (LPH) and steam-assisted crystallization (SAC), called as dry-gel conversion method, respectively. The crystals were identified by XRD and SEM. The results show that the aging time and the water content are crucial in the synthesis of zeolites. Indeed, well formed zeolite crystals are obtained by the SAC technique using a lower amount of water than in the LPH method. However, the presence of the structure directing agent (SDA) into the dry gel determines the crystallization of silicalite-1.

European Journal of Immunogenetics, 2008

The presence of certain vitamin D receptor (VDR) genotypes has been associated with low bone mine... more The presence of certain vitamin D receptor (VDR) genotypes has been associated with low bone mineral density (BMD) in elderly populations as well as with accelerated bone loss in patients with rheumatoid arthritis (RA). In the present study, VDR genotypes from 120 Spanish patients with RA were investigated. Three VDR gene polymorphisms (BsmI, ApaI and TaqI) were investigated using polymerase chain reaction followed by enzymatic digestion. The distributions of VDR allelic frequencies were similar in patients and controls and therefore no influence of VDR polymorphisms on rheumatoid arthritis susceptibility could be demonstrated. However, in an analysis of the clinical features of the different VDR-related genetic subgroups, the BB/tt genotype, defined by the BsmI and TaqI restriction site polymorphisms, was identified to be weakly associated with an early onset RA in female patients. This VDR genotype has been associated with a low BMD level in various studies. When patients were stratified according to the presence of the shared HLA epitope SE, it was found that SE + female patients bearing the BB/tt genotype showed the earliest disease onset. The mechanisms by which the VDR polymorphism is associated with RA is unknown, but they could be related to the immunoregulatory properties of vitamin D.