Multilayer silica-methacrylate hybrid coatings prepared by sol–gel on stainless steel 316L: Electrochemical evaluation

AISI 316L stainless steel is a biocompatible alloy used in prosthetic devices for many years. However this alloy tends to suffer localized corrosion and needs external fixation to hard tissues. This work describes the development of a coating system of two layers with complementary properties. The inner layer is prepared using TEOS and MTES that has already shown good anticorrosion properties. The top layer is a new hybrid organic–inorganic coating prepared with TEOS, 3-methacryloxypropyl trimethoxysilane (MPS), and 2-hydroxyethyl methacrylate (HEMA). The properties of this sol let to produce a thick and porous coating formed by two interpenetrating (organic and inorganic) networks. This coating could be an excellent container for the later aggregate of bioactive particles as the following step in a future work based on its high thickness, plasticity and open structure to allow the electrolyte access to induce the formation of hydroxyapatite. The coating is electrochemically characterised in simulated body fluid at 37 °C after 1, 10 and 30 days of immersion by means of assays as electrochemical impedance spectroscopy (EIS) and polarization curves. The dual coating seems to join the best properties of the individual ones in time: their thickness restrict the passage of potentially toxic ions to the body fluid, the breakdown potential (Eb) remains high and far from the corrosion potential (Ecorr) and the film presents the open structure of the outer layer that allows the entrance of the electrolyte to react with the particles when added to the sol meanwhile the inner layer maintain its corrosion protective features.Peer reviewe

Strength distribution of solar magnetic fields in photospheric quiet Sun regions

The magnetic topology of the solar photosphere in its quietest regions is hidden by the difficulties to disentangle magnetic flux through the resolution element from the field strength of unresolved structures. The observation of spectral lines with strong coupling with hyperfine structure, like the observed MnI line at 553.7 nm, allows such differentiation. The main aim is to analyse the distribution of field strengths in the network and intranetwork of the solar photosphere through inversion of the MnI line at 553.7 nm. An inversion code for the magnetic field using the Principal Component Analysis (PCA) has been developed. Statistical tests are run on the code to validate it. The code has to draw information from the small-amplitude spectral feature oppearing in the core of the Stokes V profile of the observed line for field strengths below a certain threshold, coinciding with lower limit of the Paschen-Back effect in the fine structure of the involved atomic levels. The inversion of the observed profiles, using the circular polarization (V) and the intensity (I), shows the presence of magnetic fields strengths in a range from 0 to 2 kG, with predominant weak strength values. Mixed regions with mean strength field values of 1130 and 435 Gauss are found associated with the network and intranetwork respectively. The MnI line at 553 nm probes the field strength distribution in the quiet sun and shows the predominance of weak, hectoGauss fields in the intranetwork, and strong, kiloGauss fields in the network. It also shows that both network and intranetwork are to be understood at our present spatial resolutions as field distributions of which we hint the mean properties.Comment: 10 pages, 6 figure

Fracturas diafisarias de húmero en adultos: estudio retrospectivo de 53 casos

Se estudian retrospectivamente 53 pacientes adultos con fractura diafisaria de húmero, 36 de los cuales siguieron el tratamiento ortopédico funcional. En otros 17 casos, pacientes politraumatizados o con fracturas de tercio medio transversas, realizamos tratamiento quirúrgico. La edad media de los pacientes fue 48 ± 2 2 años. Se afectó más el lado derecho, siendo el antecedente etiológico más frecuente el accidente casual. No hubo diferencia entre el tiempo de consolidación con el tratamiento ortopédico-funcional (60 ± 14 días) y el tratamiento quirúrgico (56 ±1 2 días). Como complicaciones hubo 7 pseudoartrosis (4 tras tratamiento ortopédico-funcional y 3 tratamiento quirúrgico). La edad media de los pacientes con pseudoartrosis fue superior a la de los pacientes con consolidación completa. Ocho casos cursaron con lesión del nervio radial, obteniendo una recuperación funcional del 100% en un tiempo medio de 38 ± 30 semanas. Valorando los resultados con arreglo a los criterios de Gayet, hemos obtenido un 80% de buenos y muy buenos resultados con tratamiento ortopédico funcional y un 70% con tratamiento quirúrgico.Fifty three adult patients with fracture of the humeral shaft were retrospectively studied. Orthopaedic-functional treatment was applied in 36 cases. Seventeen patients with either multiple injuries or transverse middle-shaft fractures were surgically treated. The mean age of patients was 48 ± 21 years. Right side was most frecuently affected and casual fall was the predominated etiology. There were no differences regarding the average consolidation period between fractures treated conservatively (60 ± 14 days) and those undergoing surgery (56 ± 12 days). As complications, there were 7 monounions (4 conservative and 3 operative treatment). The mean age of patients with non-unions was higther than those with complete fracture consolidation. Radial nerve injury was seen in 8 cases. In all there patients, a complete functional were recovery was obtained with a mean average time of 38 ± 30 weeks. When evaluating functional results according to Gayet, satisfactory results were found in 80 per cent of patients with conservative treatment and 70 per cent of those surgically treated

Aplasia del arco posterior del Atlas

Las anomalías congénitas del arco posterior del Atlas son poco frecuentes. Se presenta el caso de una paciente, que tras sufrir un accidente se diagnosticó de aplasia parcial del atlas. Esta lesión es considerada como una variante anatómica benigna de la región cráneovertebral. Se expone el desarrollo y el significado de esta anomalía.Congenital anomalies of the posterior arch of the atlas are uncommon. This paper presents the case of a patient who, as result of an accident, was diagnosed as having a congenital partial agenesia of the posterior arch of the atlas. This finding is considered as a benign anatomical variation of the craniovertebral junction region. The development and clinical significance of this anomaly are discussed

Physical activity practice and attitudes in canarian teenagers

En el presente estudio de la población adolescente de la Comunidad Autónoma de Canarias, se evidencia que aquellos adolescentes que cumplen con las recomendaciones de práctica de Actividad Física tanto de intensidad moderada como vigorosa frente a los que no las cumplen, muestran a su vez mejores valores en la percepción del conjunto de actitudes que influyen en los niveles de práctica; competencia motriz, disfrute y valor-utilidad otorgada a la misma. Lo cual nos permite afirmar que este conjunto de factores pueden determinar el tipo y grado de participación en actividades físico-deportivas en este sector de la poblaciónIn this actual study of the adolescent population of the Autonomous Region of the Canary Islands, is evident, that teens who comply with the recommendations of practice of physical activity both of moderate intensity as vigorous intensity, compared with those which do not comply, show the best values in the perception of the set of attitudes that influence the levels of practice; perceived competence, enjoyment, perceived value. Which allows us to affirm that this set of factors can determine the type and degree of participation in physical-sport activities in this sector of the populatio

Estilos de trabajo e inteligencias múltiples

El objetivo del trabajo es determinarla validez yflabilidad del modelo dejos estilos de trabajo, fundamentado en la teoría de las Inteligencias Múltiples (IM). Primero, se analizan los componentes de dicha teoría y su incidencia en el curriculum escolar. En segundo lugar, se estudia el procedimiento de evaluación. Además, se presentan los resultados del estudio empírico realizado con una muestra de 237 alumnos pertenecientes a Educación Infantil y Primaria, escolarizados en centros públicos y privados de la Región de Murcia. Del estudio realizado se desprende que los estilos están asociados a las diferentes inteligencias; además, el inventario de estilos de trabajo arroja una validez y fiabilidad altamente consistente.________________________________ The objective of this work is to determinate the validity and reliability of the model of work styles, as set out In the theory of Multiple Intelligences (MI). First, we analyze the components of this theory and their Incidence in the school curriculum. Second, we study the evaluation procedure. Additionally, we present the results of an empirical study carried out with a sample of 237 students in public and private nursery and primary schools in the province of Murcia, Spain. The study carried out reveals that the styles are associated with the different Intelligences. Furthermore, the inventory of styles shows a highly consistent validity and reliability

On the classification and properties of noncommutative duplicates

We give an explicit description of the set of all factorization structures, or twisting maps, existing between the algebras k^2 and k^2, and classify the resulting algebras up to isomorphism. In the process we relate several different approaches formerly taken to deal with this problem, filling a gap that appeared in a recent paper by Cibils. We also provide a counterexample to a result concerning the Hochschild (co)homology appeared in a paper by J.A. Guccione and J.J. Guccione.Comment: 11 pages, no figure

Monte Carlo simulation of damage and amorphization induced by swift-ion irradiation in LiNbO3

This paper presents a Monte Carlo (MC) simulation tool which is applied to describe the ion beam induced damage generated by electronic excitation in LiNbO3. Based on a previously published thermal spike based analytical model, the MC technique allows for a more flexible and accurate treatment of the problem. A main advantage of this approach with respect to the analytical one is the possibility of studying the role of statistical fluctuations, relevant at low fluences. The paper recalls the main features of the physical model, describes the MC algorithm, and compares simulation results to experimental data (irradiations of LiNbO3 using silicon ions at 5 and 7.5 MeV and oxygen ions at 5 MeV). © 2006 American Institute of Physics.Peer Reviewe

Magnetite mineralization inside cross-linked protein crystals

Crystallization in confined spaces is a widespread process in nature that also has important implications for the stability and durability of many man-made materials. It has been reported that confinement can alter essential crystallization events, such as nucleation and growth and, thus, have an impact on crystal size, polymorphism, morphology, and stability. Therefore, the study of nucleation in confined spaces can help us understand similar events that occur in nature, such as biomineralization, design new methods to control crystallization, and expand our knowledge in the field of crystallography. Although the fundamental interest is clear, basic models at the laboratory scale are scarce mainly due to the difficulty in obtaining well-defined confined spaces allowing a simultaneous study of the mineralization process outside and inside the cavities. Herein, we have studied magnetite precipitation in the channels of cross-linked protein crystals (CLPCs) with different channel pore sizes, as a model of crystallization in confined spaces. Our results show that nucleation of an Fe-rich phase occurs inside the protein channels in all cases, but, by a combination of chemical and physical effects, the channel diameter of CLPCs exerted a precise control on the size and stability of those Fe-rich nanoparticles. The small diameters of protein channels restrain the growth of metastable intermediates to around 2 nm and stabilize them over time. At larger pore diameters, recrystallization of the Fe-rich precursors into more stable phases was observed. This study highlights the impact that crystallization in confined spaces can have on the physicochemical properties of the resulting crystals and shows that CLPCs can be interesting substrates to study this process