Pressure dependence of Raman modes in double wall carbon nanotubes filled with α-Fe.

The preparation of highly anisotropic one-dimensional (1D) structures confined into carbon nanotubes (CNTs) in general is a key objective in CNTs research. In this work, the capillary effect was used to fill double wall carbon nanotubes with iron. The samples are characterized by Mössbauer and Raman spectroscopy, transmission electron microscopy, scanning area electron diffraction, and magnetization. In order to investigate their structural stability and compare it with that of single wall carbon nanotubes (SWNTs), elucidating the differences induced by the inner-outer tube interaction, unpolarized Raman spectra of tangential modes of double wall carbon nanotubes (DWNTs) filled with 1D nanocrystallin α-Fe excited with 514 nm were studied at room temperature and elevated pressure. Up to 16 GPa we find a pressure coefficient for the internal tube of 4.3 cm−1 GPa−1 and for the external tube of 5.5 cm−1 GPa−1. In addition, the tangential band of the external and internal tubes broadens and decreases in amplitude. All findings lead to the conclusion that the outer tube acts as a protection shield for the inner tubes (at least up 16 GPa). Structural phase transitions were not observed in this range of pressure

Las prohibiciones sexuales y el delito de violación: estudio comparativo correlacional de la asociación de cinco prohibiciones sexuales con los índices de violación de diversos países del mundo

Esta investigación busca establecer la existencia de asociaciones estadísticamente significativas entre la prohibición de algunas conductas sexuales y el delito de violación. Para tal fin, se observaron distintas posturas teóricas, lo que permitió reconocer puntos de encuentro que muestran vínculos entre las prohibiciones sexuales y la violación sexual. Se planteó que las prohibiciones constituían factores de riesgo o estrés asociados al delito estudiado. Luego se procedió a realizar un estudio correlacional comparativo que cotejaba los índices de delito de distintos países, considerando sus posiciones respecto a la prohibición de cinco conductas sexuales. Los resultados condujeron a afirmar que ni la prohibición ni la permisividad se asociaban a una mayor incidencia del delito abordado, por lo que no podrían considerase un factor de riesgo asociado con el delito de violación

Phase equilibria of propane and ethane simple hydrates in the presence of methanol or ethylene glycol aqueous solutions

International audienceWe report dissociation pressures of propane and ethane simple hydrates in the presence of methanol or ethylene glycol aqueous solutions at different temperatures and various concentrations of inhibitor in aqueous solutions. The equilibrium data were generated using an isochoric pressure-search method. These data are compared with some selected experimental data from the literature on the dissociation conditions of propane and ethane simple hydrates in the presence of pure water to show the inhibition effects of the above-mentioned aqueous solutions. Comparisons are finally made between our experimental data and the corresponding literature data

INCREMENTO DE VOLUMEN DE CAVIDADES CLASE I EN MOLARES HUMANOS DURANTE EL REEMPLAZO DE RESTAURACIONES DE RESINA COMPUESTA Y AMALGAMA POR DIFERENTES GRUPOS DE OPERADORES Y SU RELACIÓN CON EL CONOCIMIENTO EN MIO

La remoción y reemplazo de las restauraciones durante la vida del paciente puede resultar en anchas y profundas cavidades, por lo que es necesario ser conservador cuando se requiere un reemplazo. Objetivo: Evaluar el incremento de volumen en cavidades clase I en molares humanos, posterior a la remoción de restauraciones de resina compuesta y amalgama dental por diferentes grupos de operadores. Materiales y métodos: Se seleccionaron 60 individuos pertenecientes a 4 grupos: Estudiantes de pregrado G1, estudiantes de postgrado G2, Profesores del Departamento de Odontología Restauradora G3 y Odontólogos Generales de Servicios Públicos G4. Cada operador respondió el Test de Conocimientos de Mínima Intervención en Odontología (MIO), y luego removió dos restauraciones; una de resina (RC) y otra de amalgama (AD). Para la preparación de las muestras se realizó una copia de la cara oclusal de los dientes con acrílico y se obtuvo un molde del diente sano. Posteriormente, se hizo la preparación Oclusal (Clase I Black), se tomó el registro del volumen inicial con material de impresión polivinil siloxano aplicando la ecuación v = m/d; se obturaron las cavidades y luego de la remoción se hizo un segundo registro para evaluar el incremento de volumen. Para el análisis se usaron modelos estadísticos descriptivos y modelos estadísticos inferenciales (ANOVA Bifactorial Univariante, MANOVA Bifactorial y relación lineal). Resultados: al comparar conocimientos de MIO y grupos de operadores (ANOVA) no encontró diferencia estadísticamente significativa. El diferencial de volumen (MANOVA) no encontró diferencia significativa entre grupos de operadores y materiales. En el estudio de relación lineal no existe relación predictiva entre Puntaje del Test de MIO e incremento de volumen de las cavidades. Conclusión: En las condiciones que se realizo esta investigación el incremento de volumen de las cavidades posterior al recambio no dependen de la experiencia individual de los diferentes grupos de operadores.Summary: The removal and substitution of restorations during the patient's life can result in wide and deep cavities. Hence, it is necessary to be conservative when a substitution is required.Objective: the purpose of this research was to evaluate the increment of volume in class I cavities after removing composite and amalgam restorations by different groups of operators. Method: 60 people belonging to one of these groups were selected: undergraduate students G1, graduate students G2, professors of the department of restorative dentistry G3, and general dentist working in public services G4. Each operator answered the test of knowledge on Minimal Invasive Dentistry (MID), and the he/she removed two restorations: one of composite (C) and other of amalgam (DA). For the reparation of the sample teeth a copy of the occlusal surface with acrylic and a mold of the healthy tooth were obtained. Later, occlusal preparation was performed (Class I Black). Initial volume was registered with polivinil siloxane material and using the equation v=m/d. then, cavities were filled and a second register or volume was performed after remotion to evaluate volume increment. Inferential statistical tests were performed to analyze the data (1-way ANOVA, MANOVA and lineal regression). Results: when comparing knowledge about MID and groups of operators, the ANOVA did not show statistically significant differences. The MANOVA analysis indicated that differential volume was not statistically significantly different among the groups of operators and materials. The lineal regression analysis indicated that there is not predictive relationship between the test of MIO's scores and increment of volume in cavities. Conclusions: Under the conditions of the present study, cavities volume increment does not depend on operator's experience

Chrastil-Type Approach for Representation of Glycol Loss in Gaseous System

International audienceGlycols are generally used to adjust the water dew-point in natural gas processes to avoid gas hydrate/ice/condensate formation. Their vaporization loss in gaseous systems may happen regularly in the petroleum industry. Glycols have very low solubility in the gas phase and because of difficulty of the corresponding measurement, few sets of experimental data are available in open literature and may not be fully satisfactory. In a previous work, we performed thermodynamic consistency tests in order to prepare reliable data sets for modeling purposes. Application of four widely used correlations in supercritical fluid industry, including the original Chrastil, Adachi and Lu, del Valle and Aguilera, and Mendez-Santiago and Teja, in which the effects of temperature, density of gas (solvent), and pressures on the solubility of glycol are generally taken into account, are investigated to represent the corresponding solubility of ethylene glycol and triethylene glycol in supercritical methane and carbon dioxide between 298.15 and 333.15 K and between 1.606 and 22.06 MPa. It is found that the absolute average deviations (AAD %) of the evaluated glycols solubility by the aforementioned equations from 57 investigated experimental values are around 27%, 18%, 31%, and 17%, respectively