669 research outputs found
Psychometric validation of the Spanish version of the Dundee Ready Education Environment Measure applied to dental students.
Aim: To carry out a psychometric evaluation of the Spanish-language version of the Dundee Ready Education Environment Measure (DREEM) applied to dental students. Methods: A total of 1,391 students from nine Spanish public schools of dentistry responded to the DREEM questionnaire. To analyse the reliability of the DREEM questionnaire, the internal consistency was assessed and a 'test-retest' carried out. Validity was evaluated through analysis of item response rate, floor and ceiling effects, corrected item-total and item-subscale correlations and factor structure. A confirmatory factor analysis was performed to analyse the structure of the original DREEM scale. Results: Cronbach's alpha coefficient for the 'Educational Climate'(EC) global scale was 0.92. In the subscales, the 'observed' Cronbach's alpha coefficients ranged between 0.57 and 0.79 and were higher than the 'expected' ones; except for the Social subscale. In the DREEM questionnaire, all of the corrected correlation coefficients between the items and the EC global scale, and the items and their corresponding subscales, were >0.2; except for items 50 and 17. All goodness-of-fit indices of confirmatory factor analysis showed acceptable values (close to one or zero, depending on the case), and there was consistency in the results. Conclusions: The Spanish-language version of the DREEM questionnaire is a reliable and valid instrument for analysing the EC for dental students and its factor structure is supported by the data. Although our findings indicate that the DREEM may be as culturally independent as was originally stated, more research should be directed at verifying the factor structure in various languages and cultural environments
Photogrammetry use in the graphic surveying of the San José Church in Elche
La Iglesia de San José en Elche, situada en la provincia de Alicante (España), está declarada Bien de Interés Cultural. Es una construcción de estilo barroco que se comenzó a ejecutar en el año 1561. SanJosé formaba parte del convento franciscano de la población, donde actualmente se sitúa la Biblioteca Municipal. Aún siendo una construcción tan singular, no existe información gráfica de la misma, por lo que se considera necesario documentarla. Para ello, se van a utilizar sistemas tradicionales de levantamientos gráficos junto con otros sistemas más actuales y económicos como es la fotogrametría por intersección directa.
Se pretende comprobar la fiabilidad de la fotogrametría frente a los sistemas tradicionales empleados en la documentación gráfica del Patrimonio edificado. Además, se busca generar ortofotos de las fachadas para representar texturas en verdadera magnitud. Otra finalidad del estudio es dar a conocer el patrimonio arquitectónico de nuestras ciudades mediante el empleo de las nuevas tecnologías.
La metodología empleada para la resolución de esta investigación se ha basado en métodos analíticos, fundamentados principalmente en la observación científica y en la medición cuantitativa. Los materiales empleados han sido: cámaras digitales, medidor láser, nivel láser, estación total con medición directa sin prima, software AutoCAD 2006 y PhotoModeler 6.
Con esta investigación se ha generado documentación gráfica del edificio que describe su estado actual. Se cree necesaria la utilización de la fotogrametría en todo levantamiento del patrimonio edificado, por ser un sistema del que se extrae mucha información y al mismo tiempo es accesible económicamente, fácil y rápido de utilizar.
Se concluye con el estudio que los resultados de la fotogrametría dependen de la escala a la que se va a grafiar el dibujo, puesto que las zonas más alejados y de peor visibilidad pueden suponer errores no aceptables. Por ello se recomienda complementar la toma de datos mediante sistemas tradicionales topográficos.The church of San José in Elche, in the province of Alicante (Spain), has been declared a Site of Special Cultural Significance. Begun in 1561, the baroque church formed part of the town’s Franciscan convent and now houses the Elche Municipal Library.
Despite the uniqueness of this building, no graphic information existed and it was thus deemed necessary for it to be documented. Traditional graphic surveying systems were used, together with more up-to-date and cheaper systems, including direct-intersection photogrammetry.
The aim was to determine the reliability of photogrammetry compared with traditional systems used in graphically documenting heritage buildings. A second objective was to produce orthophotos of the church’s exterior to present its textures in true dimensions. The study also aimed to raise awareness of the architectural heritage of our towns through the use of new technologies.
The research for this project used analytical methods involving mainly scientific observation and quantitative measurement. The following materials were used: digital cameras, laser meter, laser level, prismless total station, and AutoCAD 2006 and PhotoModeler 6 software.
The research produced graphic documentation of the building in its current condition. Photogrammetry was deemed necessary for all surveying of the building, as it is an affordable system that is both fast and easy to use, and extracts detailed information.
This study can conclude that results from photogrammetry depend on the scale at which the image is to be shown, as unacceptable errors may result from more distant and less visible areas. It is therefore recommended for all data gathered to be complemented with traditional systems of topography.Peer Reviewe
Wholegrain Consumption and Risk Factors for Cardiorenal Metabolic Diseases in Chile: A Cross-Sectional Analysis of 2016-2017 Health National Survey
Abstract: Wholegrain (WG) consumption has been associated with reduced risk factors for cardiorenal metabolic diseases (CRMD). In Latin-America. WG intake is low and scarce studies on this subject have been found. We aimed to evaluate the association between WG consumption and risk factors for CRMD in the 2016-2017 Chilean-National Health Survey. This cross-sectional study included 3110 participants representative of a total population of 11,810,647 subjects > 18 y, not taking insulin and with complete data on CRMD risk factors. Outcomes were metabolic syndrome and its components, albuminuria, and impaired glomerular filtration rate (GFR). WG consumption was categorized as regular (≥every two days), sporadic (≥once a month), and non-consumers. Associations were analyzed by multivariable logistic regressions adjusted for confounders taking into account the complex sample design of the survey. Regular WG consumers showed a lower risk of high blood pressure (OR: 0.61, 95%CI: 0.41-0.91) compared to non-consumers in fully-adjusted models. Although inverse associations were noticed with other metabolic syndrome components and impaired GFR, none was statistically significant. The association between WG and BP remained robust in the sensitivity analysis. In conclusion regular WG consumption was associated with a 39% lower risk of high blood pressure in Chilean adults. Keywords: wholegrain; cardiovascular disease; metabolic syndrome; chronic kidney disease; Latin Americ
Dicyclopentadienyl titanium and zirconium complexes with the double bridged bis(dimethylsilanodiyl) dicyclopentadienyl [(Me2Si)2(η5-C5 H3)2]2- ligand: X-ray molecular structure of [Ti{(SiMe2)2(η5-C5H3)2}Me2]
The reaction of the doubly bridged bis(1,1′,2,2′-dimethylsilanodiyl)-η5-dicyclopentadienyl titanium and zirconium complexes Full-size image (<1 K) with water gave the μ-oxo derivatives Full-size image (<1 K). Addition of one equivalent of M′R (M′ = MgCl, R = CH3, CH2SiMe3; M′ = Li, R = CH2CME2Ph) to toluene or diethyl ether solutions of Full-size image (<1 K) afforded the chloro alkyl derivatives [M{(SiMe2)2(η5-C5H3)2}CIR]Full-size image (<1 K). Compounds 3 and 4 reacted with [CPh3][B(C6F5)4] at −78°C in CD2Cl2 leading to the cationic species Full-size image (<1 K) as demonstrated by NMR spectroscopy. The titanium(III) and zirconium(III) serivatives [M{(SiMe2)2(η5-C5H3)2} (μ-Cl)2 (M = Ti (12), Zr (13)) were obtained by reduction of 1 amd 2 with one equivalent of sodium amalgam. The X-ray molecular structure of [Ti{(SiMe2)2(η5-C5H3)2}Me2] (3) has been determined by diffraction methods.Financial support for this research by DGICYT (Project PB92-0178-C) is gratefully acknowledged. A,M. is grateful to Consejeria Educación (CAM) for a fellowship
Dicyclopentadienyl zirconium and hafnium complexes with the bridged (dimethylsilanodiyl)dicyclopentadienyl [(SiMe2)(η5-C5H4)2]2 ligand. X-ray molecular structure of [Zr{(SiMe2)(η5-C5H4)2}(CH2Ph)]2(μ-O)
Reaction of the bridged (dimethylsilanediyl)dicyclopentadienyl dilithium salt [(SiMe2)(C5H4)2Li2] with MCl4, in toluene, gave the zirconium and hafnium complexes [M{(SiMe2)(η5-C5H4)2}Cl2] [M=Zr (1), Hf (2)]. Addition of two equivalents of M′R (M′=MgCl, R=CH3; M′=Li, R=CH2CMe2Ph; M′=MgBz, R=CH2Ph) to toluene or diethyl ether solutions of [M{(SiMe2)(η5-C5H4)2}Cl2] afforded the dialkyl derivatives [M{(SiMe2)(η5-C5H4)2}R2] [R=CH3, M=Zr (3), Hf (4); R=CH2CMe2Ph, M=Zr (5), Hf (6); R=CH2Ph, M=Zr (7)]. Compound 1 reacted with LiMe and Mg(CH2Ph)2(THF)2 in the presence of a stoichiometric amount of water to give the μ-oxo derivatives [Zr{(SiMe2)(η5-C5H4)2}R]2(μ-O) [R=CH3 (8), CH2Ph (9)]. The X-ray molecular structure of [Zr{(SiMe2)(η5-C5H4)2}(CH2Ph)]2(μ-O) (9) has been determined by diffraction methods. Its most remarkable feature is the planarity of the BzZrOZrBz and the linearity of the ZrOZr systems.We acknowledge the Dirección General de Investigación Científica y Técnica (Spain) for financial support of this research (Project PB97-0776)
Amino-acid-based surfactants: New antimicrobial agents
The rapid increase of drug resistant bacteria makes necessary the development of new antimicrobial agents. Synthetic amino acid-based surfactants constitute a promising alternative to conventional antimicrobial compounds given that they can be prepared from renewable raw materials. In this review, we discuss the structural features that promote antimicrobial activity of amino acid-based surfactants. Monocatenary, dicatenary and gemini surfactants that contain different amino acids on the polar head and show activity against bacteria are revised. The synthesis and basic physico-chemical properties have also been included
Silyl and siloxanediyl cyclopentadienyl titanium and zirconium complexes: synthesis and reactivity. X-ray molecular structure of [Zr{η5-C5H4SiMe2(μ-OH)}(μ-Cl)Cl2]2
Chloro(dimethyl)silyl-η5-cyclopentadienyl group 4 metal complexes of the type [M(η5-C5H4Cl)Cl3] (Full-size image (<1 K)) react with thallium salts Tl(C5H4R) (R = H, SiMe3) to give mixed dicyclopentadienyl derivatives [M(η5-C5H4R)(η5-C5H4SiMe2Cl)Cl2], (M = Ti, R = H 3, R = SiMe34; M = Zr, R = H 5, R = SiMe36) in high yield. Hydrolysis of complexes 3 and 4 affords the dinuclear complexes [Ti(η5-C5H4R)Cl2]2{μ-[(η5-C5H4SiMe2)2O]}] [R = H 7, R = SiMe38) containing a siloxanyl bridge, by elimination of two equivalents of HCl. Reactions of complexes 1 with hydroxo containing reagents such as anhydrous LiOH and SiPh2(OH)2 give the derivatives [Ti(η5-C5H4SiMe2Cl)Cl2]2(μ-O)], 9 and Ti[μ-(η5-C5H4SiMe2OSiPh2-η1-O)]Cl2, 10 identified by analytical, spectrometric and spectroscopic data. Treatment of analogous complex 2 with water produces the dimeric monocyclopentadienyl zirconium trichloride adduct [Zr(η5-C5H4SiMe2OH)Cl3]2, 11. Compound 11 has been characterized by X-ray crystallography.Universidad de AlcaláConsejería de Educación de la Comunidad de Madri
Lichenysin-geminal amino acid-based surfactants: Synergistic action of an unconventional antimicrobial mixture
Recently it has been demonstrated that catanionic mixtures of oppositely charged surfactants have improved physicochemical-biological properties compared to the individual components. Isotherms of mixtures of an anionic biosurfactant (lichenysin) and a cationic aminoacid surfactant (C-3(LA)(2)) indicate a strong interaction suggesting the formation of a new 'pseudo-surfactant'. The antimicrobial properties of the mixture lichenysin and C-3(LA)(2) M80:20, indicate a synergistic effect of the components. The mechanism of action on the bacterial envelope was assessed by flow cytometry and Transmission Electron Microscopy. (C) 2016 Elsevier B.V. All rights reserved. Keywords: Antimicrobial properties; Arginine; Escherichia coli; Flow cytometry; Gemini surfactants; Lichenysin; Listeria nonocytogenes; Potassium leakage; Transmission electron microscopy
Neutral and cationic di(tert-butyl) cyclopentadienyl titanium, zirconium and hafnium complexes. Dynamic NMR study of the ligand-free cations [M(1,3-tBu2-η5-C5H3)(η5-f5H5)(CH3)]+(M=Zr, Hf)
Group 4 metal complexes containing the di(tert-butyl)cyclopentadienyl ligand (l,3-tBu2-r/5-CsH3) have been synthesized. The\ud
reaction of a mixture of 1,3- and 1,4-di(tert-butyl)cyclopentadiene isomers with KH in THF at -78°C gives the salt K+[(1,3 -\ud
tBu2CsH3)]-(THF)I_3 2 as a white solid. Treatment of 2 with chlorotrimethylsilane in a 1:1 molar ratio gives the air-stable\ud
trimethylsilylcyclopentadienyl derivative Si(1,3-tBu2C5H3XCH3)3 3. The silyl derivative 3 is an excellent precursor for monocyclopentadienyl\ud
trichlorotitanium and zirconium compounds M(1,3 -t Bu 2-r/5-C 5 H 3)C13 [M = Ti (4), Zr (5)]. Addition of a stoichiometric amount\ud
of water in the presence of NEt 3 to a toluene solution of 4 affords the oxo trimer compound [Ti(1,3-tBu2-~75 - CsH3)CI( p,-O)] 3 6. The\ud
reaction of 4 with 2 equiv, of LiMe affords the chloro dimethyl derivative Ti(1,3-tBu2-'r/5-CsH3)CI(CH3)2 7. The mixed dicyclopentadienyl\ud
compounds M(1,3-tBu2-r/5-CsH3XCsHs)CI2 [M = Ti (8); Zr (9)] were prepared by reaction of complexes 4 and 5 respectively with\ud
TI(CsHs). Treatment of complexes (8) and (9) with the appropriate alkylating reagent and molar ratio, in hexane at -78 °C, gives the\ud
chloro alkyl derivatives M(1,3-tBu2-@-C5H3XCsHs)CIR [M = Ti, R = Me (10); M = Zr, R = Me (11), Bz (12)] or the dialkyl\ud
complexes M(1,3-tBu2-@-CsH3)(CsHs)Rz [M = Ti, R = Me (13); M = Zr, R = Me (14), Bz (15), Nf (16)]. When 8 reacts with 2 equiv.\ud
of MgBz2(THF) 2 or LiCH2CMe2Ph the metallacyclic complexes Ti(1-tBu-3-CMe2CH~-r/5-C~Ha)(CsHs)R [R = Bz (17); Nf (18)] were\ud
isolated as red oils at room temperature, with the elimination of toluene or ten-butyl benzene respectively. The previously reported\ud
cationic mono 1,3-di(tert-butyl)cyclopentadienyl dibenzyl zirconium species [Zr(1,3 -t Bu 2-'05-C 5 H 3 XCH 2 Ph) 2 ] + (19) can be stabilized\ud
by reaction with tBuNC or PMe 3, in CD2C12 at -78°C, and the formation of the new cationic species [Zr(1,3-tBu2-r/5-\ud
CsHa)(L)(CH2Ph)2] + [L=tBuNC (20); PMe 3 (21)] was identified by NMR spectroscopy. The reaction of B(CrFs) 3 with the\ud
monocyclopentadienyl trimethyl derivatives M(1,3-tBu2-r/5-CsH3XCH3)3 [M = Ti (22), Zr (23)], in the presence of PMe 3, gives the\ud
cationic species [M(I,3-tBu2-@-C~H3)(PMe3)2(CH3)2] + [M = Ti (24); Zr (25)], obtained as orange-yellow solids, stable at room\ud
temperature. The reaction of B(C6Fs) 3 with the metallocene dimethyl derivatives M(1,3-tBu2-r/5-CsHa)(@-CsHs)(CH3)z [M = Zr (14);\ud
Hf (26)], in a 1:1 molar ratio and in hydrocarbon solvents gives the cationic derivatives [M(1,3-tBu2-@-CsH3)(@ -\ud
CsHsXCH3)]+[(CH3)B(CrFs)3] - [M = Zr (27); Hf (28)] as yellow oils which can be stored for weeks under an inert atmosphere. When\ud
the same reactions of (14) and (26) with B(C6Fs) 3 are carried out in a 2:1 molar ratio at room temperature, the complexes\ud
{[M(1,3-tBu2-@-CsH3X@-CsH5)Me]2(/.L-Me)}[MeB(C6Fs)3] [M =Zr (29), Hf (30)] can be obtained as a mixture of syn- and\ud
anti-isomers as shown by NMR spectroscopic observations. The formation of (29) and (30) implies the stabilization of the 14-electron\ud
cationic intermediate by interaction with one methyl group of the neutral complexes (14) and (26). Complexes (27) and (28) undergo\ud
heterolytic dissociation of the Metal-MeB(C6Fs) 3 bonds, leading to the formation of the free [M(I,3-tBu2-r/5-CsH3)(r/5-CsHs)(CH3)] +\ud
14-electron species, verified by 1H DNMR spectroscopy. When compound (27) was heated at 50°C the metallacyclic cation\ud
[Zr(1-tBu-3-CMezCH2-@-C5H3)(@-CsHs)] + (31) was formed. The alkyl derivatives synthesized and reported herein, activated with MAO, B(C6Fs) 3 or [Ph3C][B(C6Fs)4], polymerize ethylene with very low activity. The molecular structure of [Ti(1,3-tBu2-r/5-\ud
C5H3)C1(/x-O)] 3 6 has been determined by X-ray diffraction methods.Financial support for this research by DGICYT (Project PB92-0178C) is gratefully acknowledged. J.I.A.\ud
acknowledges Repsol Petróleo S.A. for a fellowship. A.M. is grateful to Consejeria Educaci6n (CAM) for a fellowship
Multilocus microsatellite typing of Leishmania infantum isolates in monitored Leishmania/HIV coinfected patients
Leishmania infantum is the main etiological agent of both visceral and cutaneous clinical forms of leishmaniasis in the Mediterranean area. Leishmania/HIV coinfection in this area is characterized by a chronic course and frequent recurrences of clinical episodes. The present study using Multilocus Microsatellite Typing (MLMT) analysis, a highly discriminative tool, aimed to genetically characterize L. infantum isolates taken from monitored Leishmania/HIV coinfected patients presenting successive clinical episodes. In this study, by the analysis of 20 microsatellite loci, we studied the MLMT profiles of 25 L. infantum isolates from 8 Leishmania/HIV coinfected patients who had experienced several clinical episodes. Two to seven isolates per patient were taken before and after treatment, during clinical and non-clinical episodes, with time intervals of 6 days to 29 months. Genetic diversity, clustering and phenetic analyses were performed. MLMT enabled us to study the genetic characteristics of the 25 L. infantum isolates, differentiating 18 genotypes, corresponding to a genotypic diversity of 0.72. Fifteen genotypes were unique in the total sample set and only 3 were repeated, 2 of which were detected in different patients. Both clustering and phylogenetic analyses provided insights into the genetic links between the isolates; in five patients isolates showed clear genetic links: either the genotype was exactly the same or only slightly different. In contrast, the isolates of the other three patients were dispersed in different clusters and some could be the result of mixing between populations. Our data indicated a great MLMT variability between isolates from coinfected patients and no predominant genotype was observed. Despite this, almost all clinical episodes could be interpreted as a relapse rather than a reinfection. The results showed that diverse factors like an intrapatient evolution over time or culture bias could influence the parasite population detected in the patient, making it difficult to differentiate between relapse and reinfection
- …