Training Graduate Students in Utilization of Analytical Instruments in a Failure Analysis Course

Department of Engineering Technology at University of North Texas offers a graduate course on failure analysis (MSET 5150) during spring semesters. Partial requirement for the course is for students to submit a term paper based on their collected data related to a term project. Case studies are given to groups of students to work on actual failed components received from area industries. Results of their findings are presented at the end of the semester in both oral presentation form and written term paper form followed the format of a well-established technical papers. Results of such exercises allows graduate students devote skills in using scientific instruments and practice manuscript preparations for publication. This paper presents examples of a case studies done by groups of students who worked on failure analysis of components failed in an oil and gas industry. Students developed skills in utilization of scanning electron microscope (SEM), Energy Dispersive Spectroscopy (EDS), and Fourier Transform Infrared Spectrophotometry. This exercise has proven highly effective in introducing young engineers to real world problems in oil and gas industry and help them develop skills needed in performing failure analysis and steps involved.Cockrell School of Engineerin

A theoretical structure-affinity relationship study of some cannabinoid derivatives

Indexación: ScieloA ZINDO/1 quantum-chemical structure-affinity relationship study with the KPG model is presented for the in vitro interaction of a group of classical, indole-derived and aminoalkylindole-derived cannabinoids with CB and CB2 receptors. From this work the following conclusions are obtained. CB and CB2 CB2 receptor affinities are regulated by different mechanisms involving orbital and charge control. Nevertheless CB and CB2 classical ligands share three common features: a hydrogen bond to a lysine (for CB ) or serine (for CB), a fully aromatic ring and a branched carbon side chain. In the case of indole-derived and aminoalkylindole-derived cannabinoids orientation and alignment rules have been defined as a basis for the comparison of noncongeneric molecules. In this way it was possible to associate the location of molecular fragments of these systems with known molecular systems such as classical cannabinoids. For aminoalkyhndoles we have proposed the locus with which they bind to a second receptor site that is available to WIN-55212-2 but not to classical cannabinoids. On the basis of our results we propose a new molecule that should help to discriminate between the above two receptor sites.http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0717-97072008000100013&nrm=is

Observation of topological Uhlmann phases with superconducting qubits

Topological insulators and superconductors at finite temperature can be characterized by the topological Uhlmann phase. However, a direct experimental measurement of this invariant has remained elusive in condensed matter systems. Here, we report a measurement of the topological Uhlmann phase for a topological insulator simulated by a system of entangled qubits in the IBM Quantum Experience platform. By making use of ancilla states, otherwise unobservable phases carrying topological information about the system become accessible, enabling the experimental determination of a complete phase diagram including environmental effects. We employ a state-independent measurement protocol which does not involve prior knowledge of the system state. The proposed measurement scheme is extensible to interacting particles and topological models with a large number of bands.Comment: RevTex4 file, color figure

Collective resonances in plasmonic crystals: Size matters

Periodic arrays of metallic nanoparticles may sustain Surface Lattice Resonances (SLRs), which are collective resonances associated with the diffractive coupling of Localized Surface Plasmon Resonances (LSPRs). By investigating a series of arrays with varying number of particles, we traced the evolution of SLRs to its origins. Polarization resolved extinction spectra of arrays formed by a few nanoparticles were measured, and found to be in very good agreement with calculations based on a coupled dipole model. Finite size effects on the optical properties of the arrays are observed, and our results provide insight into the characteristic length scales for collective plasmonic effects: for arrays smaller than 5 x 5 particles, the Q-factors of SLRs are lower than those of LSPRs; for arrays larger than 20 x 20 particles, the Q-factors of SLRs saturate at a much larger value than those of LSPRs; in between, the Q-factors of SLRs are an increasing function of the number of particles in the array.Comment: 4 figure

La participación de las familias en la escuela

Hay unanimidad desde las instancias que dictan los principios fundamentales sobre la educación en señalar que la responsabilidad natural para educar a los hijos recae en sus padres, por lo que éstos son los primeros y principales educadores de sus hijos, aunque se necesite muchas veces de ayuda. Por este motivo, la escuela va a suponer un complemento normal para su misión educativa en la sociedad en la que nos movemos, aunque no suple la responsabilidad de los padres. En este artículo se examina la participación de los padres durante los primeros años de escolaridad de sus hijos desde una perspectiva conceptual, se analizan las diversas dimensiones o grados que puede adoptar la participación de los padres, sus niveles de concreción y de agrupación, y el distinto rol que pueden adquirir los padres

Modelling a two-dimensional spatial distribution of mycotoxin concentration in bulk commodities to design effective and efficient sample selection strategies

Mycotoxins in agricultural commodities are a hazard to human and animal health. Their heterogeneous spatial distribution in bulk storage or transport makes it particularly difficult to design effective and efficient sampling plans. There has been considerable emphasis on identifying the different sources of uncertainty associated with mycotoxin concentration estimations, but much less on identifying the effect of the spatial location of the sampling points. This study used a two-dimensional statistical modelling approach to produce detailed information on appropriate sampling strategies for surveillance of mycotoxins in raw food commodities. The emphasis was on deoxynivalenol (DON) and ochratoxin A (OTA) in large lots of grain in storage or bulk transport. The aim was to simulate a range of plausible distributions of mycotoxins in grain from a set of parameters characterising the distributions. For this purpose, a model was developed to generate data sets which were repeatedly sampled to investigate the effect that sampling strategy and the number of incremental samples has on determining the statistical properties of mycotoxin concentration. Results showed that, for most sample sizes, a regular grid proved to be more consistent and accurate in the estimation of the mean concentration of DON, which suggests that regular sampling strategies should be preferred to random sampling, where possible. For both strategies, the accuracy of the estimation of the mean concentration increased significantly up to sample sizes of 40-60 (depending on the simulation). The effect of sample size was small when it exceeded 60 points, which suggests that the maximum sample size required is of this order. Similar conclusions about the sample size apply to OTA, although the difference between regular and random sampling was small and probably negligible for most sample sizes

Notas sobre la flora de la Cordillera Central, I. Pterophyta.

Sin resume

Quadratic cavity soliton optical frequency combs

We theoretically investigate the formation of frequency combs in a dispersive second-harmonic generation cavity system, and predict the existence of quadratic cavity solitons in the absence of a temporal walk-off

Propuesta de indicadores para valorar la calidad de los programas de educación preescolar

El objetivo de este artículo es dar a conocer dos aspectos: por un lado, justificar la dificultad que existe a la hora de plantear un programa educativo de calidad para la etapa de educación preescolar. Por otro lado, derivado de esta dificultad, el artículo enuncia los indicadores a los que se puede prestar atención para poder identificar un programa de calidad en educación preescolar. Se espera que esta información sea clarificadora para padres y educadores, en orden a enjuiciar cualquier intervención educativa