1,178 research outputs found
A Platinum molecular complex immobilised on the surface of graphene as active catalyst in alkyne hydrosilylation
Abstract
A platinum complex bearing a N‐heterocyclic carbene (NHC) ligand functionalised with a pyrene‐tag is immobilised onto the surface of reduced graphene oxide (rGO). The hybrid material composed of an organometallic complex and a graphene derivative is ready available in a single‐step process under mild reaction conditions. This methodology preserves the inherent properties of the active catalytic centre and the support. The platinum hybrid material is an efficient catalyst in hydrosilylation of alkynes and can be recycled and reused for ten runs without significant loss of activity due to its high stability. Interestingly, the catalytic properties of the platinum complex are enhanced after immobilisation onto graphene. The influence of graphene in hydrosilylation of alkynes is discussed
High-speed tunable photonic crystal fiber-based femtosecond soliton source without dispersion pre-compensation
We present a high-speed wavelength tunable photonic crystal fiber-based
source capable of generating tunable femtosecond solitons in the infrared
region. Through measurements and numerical simulation, we show that both the
pulsewidth and the spectral width of the output pulses remain nearly constant
over the entire tuning range from 860 to 1160 nm. This remarkable behavior is
observed even when pump pulses are heavily chirped (7400 fs^2), which allows to
avoid bulky compensation optics, or the use of another fiber, for dispersion
compensation usually required by the tuning device.Comment: 8 pages, 11 figure
Commercial Speech and Unhealthy Food Products: Conceptual Foundations
This article provides a critical and philosophical assessment of arguments invoked for and against the constitutional protection of commercial expression and the regulation of commercial speech with a focus on the commercialization of unhealthy food products.Journal of Law, Medicine & Ethic
The optimal method to make inferences about a linear combination of proportions
Asymptotic inferences about a linear combination of K independent binomial proportions are very frequent in applied research. Nevertheless, until quite recently research had been focused almost exclusively on cases of K≤2 (particularly on cases of one proportion and the difference of two proportions). This article focuses on cases of K>2, which have recently begun to receive more attention due to their great practical interest. In order to make this inference, there are several procedures which have not been compared: the score method (S0) and the method proposed by Martín Andrés et al. (W3) for adjusted Wald (which is a generalization of the method proposed by Price and Bonett) on the one hand and, on the other hand, the method of Zou et al. (N0) based on the Wilson confidence interval (which is a generalization of the Newcombe method). The article describes a new procedure (P0) based on the classic Peskun method, modifies the previous methods giving them continuity correction (methods S0c, W3c, N0c and P0c, respectively) and, finally, a simulation is made to compare the eight aforementioned procedures (which are selected from a total of 32 possible methods). The conclusion reached is that the S0c method is the best, although for very small samples (n i ≤ 10, ∀ i) the W3 method is better. The P0 method would be the optimal method if one needs a method which is almost never too liberal, but this entails using a method which is too conservative and which provides excessively wide CIs. The W3 and P0 methods have the additional advantage of being very easy to apply. A free programme which allows the application of the S0 and S0c methods (which are the most complex) can be obtained at http://www.ugr.es/local/bioest/Z_LINEAR_K.EXE
Numerical explicit analysis of hole flanging by single-stage incremental forming
The use of Single-Point Incremental Forming (SPIF) technology in hole flanging operations using multi-stages strategies have been widely studied in the last few years. However, these strategies are very time-consuming, limiting its industrial application.In a very recent work of the authors, the capability of SPIF process to successfully perform hole-flanges using a single-stage strategy has been experimentally investigated. The aim of the present work is to develop a numerical model of this process to beable to predict the sheet failure as a function of the size of the pre-cut hole. The numerical results are compared and discussed in the light of experimental tests over AA7075-O metal sheets with 1.6mm thickness.Ministerio de Economía y Competitividad DPI2015-64047-
Valoración clínico-radiológica de la articulación femoropatelar en prótesis que conservan los ligamentos cruzados
Se realizó un estudio retrospectivo en 104 pacientes con 116 prótesis tricompartimentales
de rodilla que conservan los dos ligamentos cruzados. Se analizó la situación
radiológica de la rótula, su relación con el implante protésico y los efectos de estos
factores sobre la movilidad de la rodilla. Se realizaron proyecciones radiográficas AP,
lateral y axial a 30° y se obtuvieron las siguientes variables: espesor residual rotuliano,
posición del componente metálico respecto a la rótula, ángulo de Laurin, y grado de subluxación
rotuliana. Se comparó la relación existente entre las diferentes variables, y éstas
con respecto a los grados de flexión. Un 52,2% de las patelas presentaban una alineación
central. Se obtuvo una relación significativa entre el ángulo de inclinación y el grado
de subluxación patelar, sin embargo las variables a estudio no han presentado influencia
en el grado de movilidad protésica, dentro de los rangos expuestos.A retrospective study was performed in 104 patients with 116 tricompartimental non-constrained knee prostheses. The radiological possition of the patella, its relationwith the prosthetic implant and the effect of these factors in the final range of movement of the knee were analyzed. AP, lateral and 30° axial radiological views were taken and the following variables were studied: residual patellar thickness, position of the metallic component with respect to the patella, Laurin''s angle and subluxation of the patella.The relation between these findings and also respect to postoperative maximum flexion were investigated. Overall, 52% of the patella tracked centrally. A statystical significant relation between the inclination angle and the patellar subluxation degree was obtained. However, within the exposed ranges, the studied variables have not demonstrated influence in the prosthetic range of movement
Studying the Pygmy Dipole Resonances with isoscalar and isovector probes
We present a short review of the properties of the so-called Pygmy Dipole
Resonance (PDR) which can be studied with both isovector and isoscalar probes. This is
possible due to the particular property of this new mode where the isoscalar and isovector
characters are mixed. The use of both probes unveils new features which otherwise will remain
hidden. It is of paramount importance the use of a proper description of these modes, taking
into account their main features, in order to have a good description of the experimental data.Ministerio de Ciencia, Innovación y Universidades de España y fondos europeos FEDER - FIS2017-88410-
Síndrome del túnel tarsiano: a propósito de un caso
El Síndrome del túnel tarsiano está causado por el atrapamiento del nervio tibial
posterior o sus ramas a nivel del retináculo flexor en el tobillo. Se describe un caso de síndrome
de túnel tarsiano causado por un quiste sinovial. El paciente refería dolor desde hacía 1
mes a nivel retromaleolar irradiado a planta del pie y primer dedo. Al mes de iniciado los síntomas
se apreció una tumoración a nivel retromaleolar. Se exponen los hallazgos EMG, ecografía
y R.M.N. Cuando la causa de esta entidad es una lesión ocupante de espacio, está indicada
la cirugía, siendo el pronóstico mejor cuanto más precoz es la intervención.Tarsal tunnel syndrome is an entrapment neuropathy caused by compression of
the posterior tibial nerve or one of its branches beneath the ankle flexor retinaculum. We present
a case of tarsal tunnel syndrome caused by synovial cyst. Since one month the patient
complained about pain retromaleolarly radiating to the sole of the foot and first toe. At retromaleolar
level a mass was found one month after the onset of symptoms. We report the
E.M.G., ultrasonography and R.N.M. findings. When the cause of this syndrome is a space-occupying
lesion surgery is indicated. The results of surgery are worse when operation is delayed
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