An integrated pharmacokinetic and pharmacodynamic study of a new drug of abuse, methylone, a synthetic cathinone sold as 'bath salts'

Material and methods. Methylone was administered to male Sprague-Dawley rats intravenously (10 mg/kg) and orally (15 and 30 mg/kg). Plasma concentrations and metabolites were characterized by LC/MS and LC-MS/MS fragmentation patterns. Locomotor activity was monitored for 180-240 min. Results. Oral administration of methylone induced a dose-dependent increase in locomotor activity in rats. The plasma concentrations after i.v. administration were described by a two-compartment model with distribution and terminal elimination phases of α = 1.95 h− 1 and β = 0.72 h− 1. For oral administration, peak methylone concentrations were achieved between 0.5 and 1 h and fitted to a flip-flop model. Absolute bioavailability was about 80% and the percentage of methylone protein binding was of 30%. A relationship between methylone brain levels and free plasma concentration yielded a ratio of 1.42 ± 0.06, indicating access to the central nervous system. We have identified four Phase I metabolites after oral administration. The major metabolic routes are N-demethylation, aliphatic hydroxylation and O-methylation of a demethylenate intermediate. Discussion. Pharmacokinetic and pharmacodynamic analysis of methylone showed a correlation between plasma concentrations and enhancement of the locomotor activity. A contribution of metabolites in the activity of methylone after oral administration is suggested. Present results will be helpful to understand the time course of the effects of this drug of abuse in humans.

An integrated pharmacokinetic and pharmacodynamic study of a new drug of abuse, methylone, a synthetic cathinone sold as 'bath salts'

Material and methods. Methylone was administered to male Sprague-Dawley rats intravenously (10 mg/kg) and orally (15 and 30 mg/kg). Plasma concentrations and metabolites were characterized by LC/MS and LC-MS/MS fragmentation patterns. Locomotor activity was monitored for 180-240 min. Results. Oral administration of methylone induced a dose-dependent increase in locomotor activity in rats. The plasma concentrations after i.v. administration were described by a two-compartment model with distribution and terminal elimination phases of α = 1.95 h− 1 and β = 0.72 h− 1. For oral administration, peak methylone concentrations were achieved between 0.5 and 1 h and fitted to a flip-flop model. Absolute bioavailability was about 80% and the percentage of methylone protein binding was of 30%. A relationship between methylone brain levels and free plasma concentration yielded a ratio of 1.42 ± 0.06, indicating access to the central nervous system. We have identified four Phase I metabolites after oral administration. The major metabolic routes are N-demethylation, aliphatic hydroxylation and O-methylation of a demethylenate intermediate. Discussion. Pharmacokinetic and pharmacodynamic analysis of methylone showed a correlation between plasma concentrations and enhancement of the locomotor activity. A contribution of metabolites in the activity of methylone after oral administration is suggested. Present results will be helpful to understand the time course of the effects of this drug of abuse in humans.

Implementación de técnicas de estimación y sincronización para sistemas OFDM: aplicación directa sobre la implementación de la capa física del estándar DVB-T

El sistema de modulación ODFM es utilizado en diversas aplicaciones de banda ancha, tanto en comunicaciones por cable como en aplicaciones inalámbricas. Presenta numerosas ventajas frente a sistemas de banda ancha de portadora única ya que permite una alta eficiencia espectral, una fácil ecualización y una reducción del ISI. Por el contrario, presenta dificultades inherentes a su estructura, que son de vital importancia solventar, entre las cuales se encuentran los altos requisitos de sincronización. Este proyecto presenta métodos de sincronización de tiempo y frecuencia implementados y evaluados sobre una plataforma software basada en Matlab®, que recoge el sistema completo de transmisión basado fielmente en el estándar DVB-T. Tras una presentación de los principios de la modulación OFDM, en este documento se presenta un estudio detallado de este sistema de transmisión y su implementación, formando conjuntamente una plataforma de simulación para la evaluación de los estimadores implementados.

Muntatge i automatització d'un ascensor de 4 plantes

Treball de recerca realitzat per alumnes d'ensenyament secundari i guardonat amb un Premi CIRIT per fomentar l'esperit cientí­fic del Jovent l'any 2009. Les primera intenció d'aquesta recerca és unificar dues grans branques de la tecnologia com són la mecànica i l'elèctronica. Així va sorgir el projecte de construir un ascensor i provar un nou sistema de transmissió com és el vis sense fi juntament amb la introducció d'un microcontrolador del tipus PIC com a unitat central de processament. El primer pas d'aquest treball va ser el disseny d'aquest ascensor utilitzant diversos programes. Posteriorment es van encarregar aquestes peces abans dissenyades per tal de començar-ne la construcció. Aquestes peces van ser unides totalment mitjançant rebladures i altres suports mecànics. A continuació es va desenvolupar la programació del microcontrolador. El pas més important va ser l'acoblament del grup motor i el poliment dels aspectes més difícils de corregir com és el cas dels molts fregaments que patia al ser una estructura purament metàl·lica. Corregits aquests problemes i el nivell sonor, es va donar per conclòs el treball.

Stream Radio Community : comunitat web per la difusió de radio via streaming

Desenvolupament d'una aplicació web amb projecció a comunitat virtual d’usuaris, que també integra un sistema de transmissió de streaming. Mitjançant aquest sistema els usuaris són capaços d’emetre o d’escoltar un programa radiofònic en temps real o offline.

Actively maintained lipid nanodomains in biomembranes

Lipid rafts, defined as domains rich in cholesterol and sphingolipids, are involved in many important plasma membrane functions. Recent studies suggest that the way cells handle membrane cholesterol is fundamental in the formation of such lateral heterogeneities. We propose to model the plasma membrane as a nonequilibrium phase-separating system where cholesterol is dynamically incorporated and released. The model shows how cellular regulation of membrane cholesterol may determine the nanoscale lipid organization when the lipid mixture is close to a phase separation boundary, providing a plausible mechanism for raft formation in vivo.

Hysteresis in a system driven by either generalized force or displacement variables: martensitic phase transition in single-crystalline Cu-Zn-Al

We report on experiments aimed at comparing the hysteretic response of a Cu-Zn-Al single crystal undergoing a martensitic transition under strain-driven and stress-driven conditions. Strain-driven experiments were performed using a conventional tensile machine while a special device was designed to perform stress-driven experiments. Significant differences in the hysteresis loops were found. The strain-driven curves show reentrant behavior yield point which is not observed in the stress-driven case. The dissipated energy in the stress-driven curves is larger than in the strain-driven ones. Results from recently proposed models qualitatively agree with experiments.

Metastable liquid-liquid phase transition in a single-component system with only one crystal phase and no density anomaly

We investigate the phase behavior of a single-component system in three dimensions with spherically-symmetric, pairwise-additive, soft-core interactions with an attractive well at a long distance, a repulsive soft-core shoulder at an intermediate distance, and a hard-core repulsion at a short distance, similar to potentials used to describe liquid systems such as colloids, protein solutions, or liquid metals. We showed [Nature (London) 409, 692 (2001)] that, even with no evidence of the density anomaly, the phase diagram has two first-order fluid-fluid phase transitions, one ending in a gas¿low-density-liquid (LDL) critical point, and the other in a gas¿high-density-liquid (HDL) critical point, with a LDL-HDL phase transition at low temperatures. Here we use integral equation calculations to explore the three-parameter space of the soft-core potential and perform molecular dynamics simulations in the interesting region of parameters. For the equilibrium phase diagram, we analyze the structure of the crystal phase and find that, within the considered range of densities, the structure is independent of the density. Then, we analyze in detail the fluid metastable phases and, by explicit thermodynamic calculation in the supercooled phase, we show the absence of the density anomaly. We suggest that this absence is related to the presence of only one stable crystal structure.