1,263 research outputs found
Kinetico-mechanistic studies on substitution reactions on cross-bridged cyclen CoIII complexes with nucleosides and nucleotides
Kinetico-mechanistic studies on the substitution reactivity of the [Co{(μ-ET)cyclen}(H2O)2] 3+ complex cation at pH values within the 6.0-7.0 range with biologically significant ligands have been carried out. The substitution processes have been found to occur exclusively on the mono-hydroxobridged [(Co{(μ-ET)cyclen}(H2O))2(μ-OH)]5+ species formed after equilibration of the cobalt complex in the relevant medium. The studies conducted on the substitution of the aqua/hydroxo ligands of this dinuclear species are indicative of a dominant role of outer-sphere complexation, involving hydrogen-bonding interactions. The values of the outer-sphere complex formation equilibrium constant are in line with the intervention of both the exiting aqua ligands and the NH groups at the encapsulating {(μ-ET)cyclen} ligand. These complexes result in the preferential formation of O- or N-bonded nucleotides depending on the structure of the base moiety of the ligand. Even the entry of the different donor bonded nucleotides is hampered by the hydrogen-bonding interaction with the dangling moiety of an already coordinated ligand. In general the overall substitution processes occur at a faster rate than those published for the fully alkylated encapsulating {(Me)2(μ-ET)cyclen} ligand derivative, as expected for the still available base-catalysing NH groups in the {(μ-ET)cyclen} ligand
ZIF-67 In Situ Grown on Attapulgite: A Flame Retardant Synergist for Ethylene Vinyl Acetate/Magnesium Hydroxide Composites.
ZIF-67@ATP was prepared by the in situ growth of the zeolite imidazole frame (ZIF-67)
on the surface of attapulgite (ATP). The structure and surface morphology of ZIF-67@ATP were
characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), X-ray
photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and transmission electron
microscopy (TEM). Different mass fractions of ATP and ZIF-67@ATP were added to ethylene vinyl
acetate (EVA)/magnesium hydroxide (MH) composites as flame retardant synergists. The flame
retardancy of EVA composites was evaluated by the limiting oxygen index (LOI) test, UL-94 test
and cone calorimeter test. Composites containing 3 wt% of ZIF-67@ATP reached an LOI value of
43% and a V-0 rating in the UL-94 test, and the ignition time of the composite increased from 38 s
to 56 s. The tensile strength and impact strength of the composites did not change significantly, but
the elongation at break increased greatly. Typically, for composites containing 4 wt% of ZIF-67@ATP,
the elongation at break of the composites increased from 69.5% to 522.2% compared to the samples
without the synergist. This study provides novel insights into the application of attapulgite in the
field of flame retardant polymer materials.post-print3999 K
Maíz de alto contenido proteínico (Zea mays l.) en hogares rurales marginados del estado de Puebla
El déficit en ingesta diaria de proteínas y calorías registrado en la población infantil mexicana, se muestra de modo extremo en áreas rurales. El déficit se agudiza por la problemática económica y sanitaria actual, lo que se constituye en un problema alimentario de naturaleza nacional. En este trabajo se estudió el nivel de aceptabilidad del maíz de alta calidad proteínica (ACP) con el cálculo de un índice de aceptabilidad, con información de 78 productores, del sur del estado de Puebla, que participan en un programa de la SDR, caracterizados por IDH bajo y alto índice de desnutrición. Se aplicó un cuestionario de 51 preguntas a una muestra por muestreo aleatorio simple, con grado de confiabilidad de 95%. Se encontró que la semilla del maíz ACP se distribuye con sus atributos proteínicos, pero con una deficiente transferencia de tecnología; con índice de aceptabilidad del 60%, que muestra buena aceptación para ser sembrado por los productores. Lo siembran uno, dos o tres años, valorando sus circunstancias para repetirlo en ciclos siguientes, ignorando sus propiedades proteínicas. El consumo, del maíz ACP se incorpora al forraje para animales de traspatio y esporádicamente en la dieta de la familia
EVALUACIÓN DE EMERGENCIA DEL MAIZ CRIOLLO CON DISTINTOS PORCENTAJES DE HUMEDAD
ResumenLa investigación se llevó a cabo durante el ciclo primavera-verano 2017, en el Tecnológico Nacional de México Instituto Tecnológico Roque (ITR), en el estado de Guanajuato, México, ubicado a una altitud de entre 1700 a 1800 metros sobre el nivel del mar. El propósito del experimento es evaluar la humedad adecuada y eficiente requerida por la semilla de maíz criollo para obtener un índice tasa de emergencia.En el manejo de un cultivo es de gran importancia que el productor considere la fecha de siembra, la densidad de siembra, la fertilización, así como la disponibilidad de agua de un suelo y su textura, la profundidad de siembra y evaluar cuantitativamente la humedad disponible en el suelo de cultivo.Palabra(s) Clave(s): emergencia, índice, maíz criollo, tasa AbstractThe research was carried out during the spring-summer 2017 cycle, in the Roque technological institute, in the state of Guanajuato, Mexico located at an altitude of 1700 to 1800 meters above sea level. The purpose of the experiment is to evaluate the adequate and efficient humidity required by the native corn seed to obtain a high rate of emergence.In the management of a crop it is of great importance that the producer consider the date of sowing, the density of sowing, the fertilization, as well as the availability of water of a soil and its texture, the depth of sowing and quantitative evaluation of the available humidity on the growing soil.Keywords: emergency, index, maize, rate
Influence of Femtosecond Laser Modification on Biomechanical and Biofunctional Behavior of Porous Titanium Substrates
[Abstract] Bone resorption and inadequate osseointegration are considered the main problems of titanium implants. In this investigation, the texture and surface roughness of porous titanium samples obtained by the space holder technique were modified with a femtosecond Yb-doped fiber laser. Different percentages of porosity (30, 40, 50, and 60 vol.%) and particle range size (100–200 and 355–500 μm) were compared with fully-dense samples obtained by conventional powder metallurgy. After femtosecond laser treatment the formation of a rough surface with micro-columns and micro-holes occurred for all the studied substrates. The surface was covered by ripples over the micro-metric structures. This work evaluates both the influence of the macro-pores inherent to the spacer particles, as well as the micro-columns and the texture generated with the laser, on the wettability of the surface, the cell behavior (adhesion and proliferation of osteoblasts), micro-hardness (instrumented micro-indentation test, P–h curves) and scratch resistance. The titanium sample with 30 vol.% and a pore range size of 100–200 μm was the best candidate for the replacement of small damaged cortical bone tissues, based on its better biomechanical (stiffness and yield strength) and biofunctional balance (bone in-growth and in vitro osseointegration).This research was funded by the Ministerio de Ciencia e Innovación del Gobierno de España (PID2019-109371GB-100), Junta de Andalucía (Spain), through the Project PAIDI P20-00671Junta de Andalucía; P20-0067
Synergy between magneto-rheological fluids and aluminum foams. Prospective alternative for seismic damping
This is the accepted manuscript. Access to the published article can be gained at: http://jim.sagepub.com/cgi/reprint/1045389X15596624v1.pdf?ijkey=SyFHNQwE4XMQqBF&keytype=finiteThis article presents the experimental study of a preliminary investigation of a seismic damper device aimed at improving the behavior of structures when subjected to earthquakes. The damper is the result of a binomial material formed by aluminum foam with pores 1 mm in diameter, wetted by a magnetorheological fluid (MRF). The objective of the present work is to explore the synergy between the two components in a magnetorheological test, and to evaluate the effect of the Al foam pores in the structure buildup of the fluid. The analysis is completed with a compressive test carried out on the MRF-filled foam in the presence of a magnetic field. This kind of test demonstrates that the deformation of the foam for very small loads is limited by the hardening of the fluid because of its MR response. The results of this research suggest that there is a mutual benefit between the components of the device, presumably leading to an enhanced dissipation of vibration energy.Proyectos PE2012-FQM694 (Junta de Andalucía, Spain), FIS2013-47666-C3-1-R (MINECO, Spain), SENER-CONACYT "151496" (UNAM Mexico), CONACYT National Quality Graduate Progra
Psychometric properties of the Three Factor Eating Questionnaire (TFEQ) / Propiedades psicométricas del Cuestionario de Tres Factores de la Alimentación (TFEQ)
Abstract. The purpose of this investigation was to evaluate the psychometric properties -internal consistency, factor analysis and the concurrent and discriminate validity- of the Three Factor Eating Questionnaire (TFEQ). 607 women ( χ̅ = 20.29, SD = 5.70), completed TFEQ, Eating Attitudes Test (EAT-40) and Bulimia Test (BULIT). Results showed an appropriate internal consistency coefficient (a = .87); two factors were extracted after principal component factor analysis that explaining 30 % of the total variance: dietary restraint and disinhibition. Also are presented the concurrent and discriminant validity that favorable to the psychometric goodness of the TFEQ benefits and support that is an appropriate instrument for assessing eating pathology.Key words: eating, binge eating, psychometric properties, eating questionnaire and factor structure.Resumen. El propósito de esta investigación fue evaluar las cualidades psicométricas -consistencia interna, análisis de factores y la validez de criterio de tipo concurrente y discriminate- del Cuestionario de Tres Factores de la Alimentación (TFEQ, por sus siglas en inglés). 607 mujeres ( χ̅ = 20.29, DE = 5.70), completaron el TFEQ, el Cuestionario de Actitudes ante la Alimentación (EAT-40) y el Cuestionario de Bulimia (BULIT). Los resultados señalan un coeficiente de consistencia interna adecuada (a = .87); posterior al análisis factorial de componentes principales se extrajeron 2 factores que explican el 30 % de la varianza total: restricción alimentaria y desinhibición. Asimismo, se presentan de validez concurrente y validez discriminante que apoyan las bondades psicométricas del TFEQ y sustentan que es un instrumento adecuado para evaluar la patología alimentaria.Palabras claves: Conducta alimentaria, atracón, propiedades psicométricas, cuestionario de alimentación y estructura factorial
Multi-technical approach for the characterization of polychrome decorative surfaces at Spanish Mission Churches in Nueva Vizcaya (Chihuahua, Mexico)
An interdisciplinary and multi-institutional group of science and art conservation specialists has provided new insight into the painting materials used in the polychrome walls and wooden ceilings in four seventeenth century Spanish colonial churches of Nueva Vizcaya (Chihuahua, Mexico). A multi-analytical study of the decorative surfaces was performed in situ using spectroscopic approaches (XRF, FORS), False Colour Infrared Reflectography – IRFC, as well as micro sampling (ATR-FTIR, LM, GC/MS). A survey of natural resources and study (ATR-FTIR, LM) was carried out to elucidate the natural occurrence of a select number of materials in the surrounding areas of the churches. The present paper presents a multi-analytical study and characterization of green, red-orange and black colour pigments and binders selected from the decorative surfaces. The aim of this study is to highlight relationships between local materials and those from the original polychrome ceilings, in order to understand the material and technological influences that converged in the Spanish colonial architecture of northern Mexico
Effectiveness of an intervention for improving drug prescription in primary care patients with multimorbidity and polypharmacy:Study protocol of a cluster randomized clinical trial (Multi-PAP project)
This study was funded by the Fondo de Investigaciones Sanitarias ISCIII (Grant Numbers PI15/00276, PI15/00572, PI15/00996), REDISSEC (Project Numbers RD12/0001/0012, RD16/0001/0005), and the European Regional Development Fund ("A way to build Europe").Background: Multimorbidity is associated with negative effects both on people's health and on healthcare systems. A key problem linked to multimorbidity is polypharmacy, which in turn is associated with increased risk of partly preventable adverse effects, including mortality. The Ariadne principles describe a model of care based on a thorough assessment of diseases, treatments (and potential interactions), clinical status, context and preferences of patients with multimorbidity, with the aim of prioritizing and sharing realistic treatment goals that guide an individualized management. The aim of this study is to evaluate the effectiveness of a complex intervention that implements the Ariadne principles in a population of young-old patients with multimorbidity and polypharmacy. The intervention seeks to improve the appropriateness of prescribing in primary care (PC), as measured by the medication appropriateness index (MAI) score at 6 and 12months, as compared with usual care. Methods/Design: Design:pragmatic cluster randomized clinical trial. Unit of randomization: family physician (FP). Unit of analysis: patient. Scope: PC health centres in three autonomous communities: Aragon, Madrid, and Andalusia (Spain). Population: patients aged 65-74years with multimorbidity (≥3 chronic diseases) and polypharmacy (≥5 drugs prescribed in ≥3months). Sample size: n=400 (200 per study arm). Intervention: complex intervention based on the implementation of the Ariadne principles with two components: (1) FP training and (2) FP-patient interview. Outcomes: MAI score, health services use, quality of life (Euroqol 5D-5L), pharmacotherapy and adherence to treatment (Morisky-Green, Haynes-Sackett), and clinical and socio-demographic variables. Statistical analysis: primary outcome is the difference in MAI score between T0 and T1 and corresponding 95% confidence interval. Adjustment for confounding factors will be performed by multilevel analysis. All analyses will be carried out in accordance with the intention-to-treat principle. Discussion: It is essential to provide evidence concerning interventions on PC patients with polypharmacy and multimorbidity, conducted in the context of routine clinical practice, and involving young-old patients with significant potential for preventing negative health outcomes. Trial registration: Clinicaltrials.gov, NCT02866799Publisher PDFPeer reviewe
- …