El proceso constituyente venezolano

RESUMEN: La Asamblea Nacional Constituyente permitirá redefinir el marco institucional de la república venezolana. Este proceso constituyente iniciado en 1989 aborda una etapa definitiva debido al apoyo mayoritario de los venezolanos y a que ha sido asumido como bandera por el hoy presidente Hugo Chávez.El paradigma constitucional ha tenido tropiezos originados por el populismo, el clientelismo, la corrupción, la falta de un trabajo legislativo oportuno, la falta de garantías a los derechos fundamentales, el deterioro del poder judicial y la falta de una participación política abierta.Para llevar a cabo una asamblea nacional constituyente es fundamental la participación amplia que lleve a un consenso constructivo. Es decir, se tratará de iniciar el 25 de abril una constituyente originaria que implica que su capacidad decisoria no esté sujeta a ningún poder establecido, ya que su origen es la expresión política de la soberanía popular que va a modificar el ordenamiento jurídico existente.ABSTRACT: The National Assembly Constituency will permit the redefinition of the institutional framework of the Venezuelan Republic. This fundamental process started in 1989 outlines a definitive stage due to the major support of the Venezuela people, and has been assumed as the platform of present president Hugo Chávez.The constitutional paradigm has flaws that originate from the following: populism, clientelism, corruption, the lack of timely legislative work, the lack of guarantees to basic rights, the deterioration of judicial power, and the lack of open political participation.For the National Assembly Constituency to work, extensive participation is fundamental to bring forth constructive consensus. As its origins now is the political expression of popular sovereignty that modifies the existing judicial order, it wil try to iniciate on the 25th of April a new constituency that implies that its capacity for decision making is not subject to any establishe power.</p

Indirect Electrografting of Aryl Iodides

International audienceThe electrografting of 4-iodonitrobenzene that is not possible directly is demonstrated whilst that of 5-iodo-2-amino-pyridine, 4-iodoaniline and iodobenzene is performed with a decrease of overpotential > 2 V. The electrografting of aryl iodides is achieved through a iodine abstraction reaction: in the presence of a sterically hindered diazonium salt (2,6-dimethylbenzenediazonium), the aryl iodide is grafted to gold at the much less negative reduction potential of the diazonium salt

Single Nanoparticle Growth from Nanoparticle Tracking Analysis: From Monte Carlo Simulations to Nanoparticle Electrogeneration

International audienceBy scrutinizing the trajectory of individual nanoparticles (NPs) in solution, NP tracking analysis (NTA) allows sizing individual NPs and providing meaningful complementary information to single NP electrochemistry.H erein, am odel is developed to extend NTAt oa llow dynamic NP sizing and to analyze the kinetics of growth of NPs in solution. Interpreting the NP trajectories as scaled Brownian motion, Monte Carlo simulations produce stochastic trajectories of growing NPs (under diffusion-controlled growth). These trajectories are grounds for determining as trategy to estimate the growth parameters of individual NPs from the time evolution analysis of the mean square displacement (MSD) curves. In particular,w ee valuate the accuracy and precision of the parameter estimates from MSD analysis. In addition, the strategy is illustrated to depict the homogeneous electrosynthesis of silver NPs from the oxidation of as acrificial Ag ultramicroelectrode (UME) in Fe 2 + solution

Optical Nanoimpacts of Dielectric and Metallic Nanoparticles on Gold Surface by Reflectance Microscopy: Adsorption or Bouncing?

International audienceOptical modeling coupled to experiments show that a microscope operating in reflection mode allows imaging, through solutions or even a microfluidic cover, various kinds of nanoparticles, NPs, over a (reflecting) sensing surface, here a gold (Au) surface. Optical modeling suggests that this configuration enables the interferometric imaging of single NPs which can be characterized individually from local change in the surface reflectivity. The interferometric detection improves the optical limit of detection compared to classical configurations exploiting only the light scattered by the NPs. The method is then tested experimentally, to monitor in situ and in real time, the collision of single Brownian NPs, or optical nanoimpacts, with an Au-sensing surface. First, mimicking a microfluidic biosensor platform, the capture of 300 nm FeOx maghemite NPs from a convective flow by a surface-functionalized Au surface is dynamically monitored. Then, the adsorption or bouncing of individual dielectric (100 nm polystyrene) or metallic (40 and 60 nm silver) NPs is observed directly through the solution. The influence of the electrolyte on the ability of NPs to repetitively bounce or irreversibly adsorb onto the Au surface is evidenced. Exploiting such visualization mode of single-NP optical nanoimpacts is insightful for comprehending single-NP electrochemical studies relying on NP collision on an electrode (electrochemical nanoimpacts)

Electrochemical Investigation of Nitinol/Tantalum Hybrid Surfaces Modified by Alkylphosphonic Self-Assembled Monolayers

The surface characteristics of bare and modified nickel-titanium samples (NiTi) are investigated by spectroscopic, microscopic and electrochemical techniques. The successful electrodeposition of a tantalum coating on NiTi and the effective grafting of 1-dodecylphosphonic acid SAMs on both pristine and Ta-covered NiTi surfaces are evidenced and quantified by XPS and SEM. Cyclic voltammetry performed on the different NiTi-based electrodes highlights their specificities regarding electron transfer to a redox probe present in solution (here ruthenium(III) hexamine). Finally, the samples electrochemical characteristics at a local scale are investigated by scanning electrochemical microscopy (SECM). The impact of the surface modifications on mass transport of the redox probe is analyzed through approach curves in the feedback mode, while the recording of current maps in feedback as well as in substrate-generation/tip-collection modes leads to the qualitative identification of electrochemically-active areas corresponding to precursor pitting corrosion sites

Quantitative localized proton-promoted dissolution kinetics of calcite using scanning electrochemical microscopy (SECM)

Scanning electrochemical microscopy (SECM) has been used to determine quantitatively the kinetics of proton-promoted dissolution of the calcite (101̅4) cleavage surface (from natural “Iceland Spar”) at the microscopic scale. By working under conditions where the probe size is much less than the characteristic dislocation spacing (as revealed from etching), it has been possible to measure kinetics mainly in regions of the surface which are free from dislocations, for the first time. To clearly reveal the locations of measurements, studies focused on cleaved “mirror” surfaces, where one of the two faces produced by cleavage was etched freely to reveal defects intersecting the surface, while the other (mirror) face was etched locally (and quantitatively) using SECM to generate high proton fluxes with a 25 μm diameter Pt disk ultramicroelectrode (UME) positioned at a defined (known) distance from a crystal surface. The etch pits formed at various etch times were measured using white light interferometry to ascertain pit dimensions. To determine quantitative dissolution kinetics, a moving boundary finite element model was formulated in which experimental time-dependent pit expansion data formed the input for simulations, from which solution and interfacial concentrations of key chemical species, and interfacial fluxes, could then be determined and visualized. This novel analysis allowed the rate constant for proton attack on calcite, and the order of the reaction with respect to the interfacial proton concentration, to be determined unambiguously. The process was found to be first order in terms of interfacial proton concentration with a rate constant k = 6.3 (± 1.3) × 10–4 m s–1. Significantly, this value is similar to previous macroscopic rate measurements of calcite dissolution which averaged over large areas and many dislocation sites, and where such sites provided a continuous source of steps for dissolution. Since the local measurements reported herein are mainly made in regions without dislocations, this study demonstrates that dislocations and steps that arise from such sites are not needed for fast proton-promoted calcite dissolution. Other sites, such as point defects, which are naturally abundant in calcite, are likely to be key reaction sites

Proyecto de Guion de la Webserie "How to Drag"

El projecte de guió de la websèrie "How to Drag". Tracta sobre la creació dels 8 guions de la primera temporada que narren la història de Ramón, qui s'inicia en el món drag i evoluciona en aquest art. El projecte s'ha desenvolupat a partir de la recerca conceptual sobre la cultura drag, els nous formats audiovisuals i una anàlisi del sector i de públic. A partir d'aquesta conceptualització s'ha elaborat la bíblia del projecte que descriu la història, els personatges, les seves trames i els guions de la primera temporada d'aquesta websèrie còmica de temàtica drag amb un tractament de mockumentary.El proyecto de guion de la webserie "How to Drag". Trata sobre la creación de los 8 guiones de la primera temporada que narran la historia de Ramón, quien se inicia en el mundo drag y evoluciona en este arte. El proyecto se ha desarrollado a partir de la investigación conceptual sobre la cultura drag, los nuevos formatos audiovisuales y un análisis del sector y de público. A partir de esta conceptualización se ha elaborado la biblia del proyecto que describe la historia, los personajes, sus tramas y los guiones de la primera temporada de esta webserie cómica de temática drag con un tratamiento de mockumentary.The screenplay project of the web series "How to Drag". It deals with the creation of the 8 screenplays of the first season that tell the story of Ramón, who starts in the drag world and evolves within this art. The project has been developed based on conceptual research on drag culture, new audiovisual formats and an analysis of the industry and the public. From this conceptualization the bible of the project describing the history, the characters, their plots and the screenplays of the first season of this comedy web series with a drag theme coded as a mockumentary

Determination of Silver(I) by Differential Pulse Voltammetry Using a Glassy Carbon Electrode Modified with Synthesized N-(2-Aminoethyl)-4,4′-Bipyridine

A new modified glassy carbon electrode (GCE) based on a synthesized N-(2-aminoethyl)-4,4′-bipyridine (ABP) was developed for the determination of Ag(I) by differential pulse voltammetry (DPV). ABP was covalently immobilized on GC electrodes surface using 4-nitrobenzendiazonium (4-NBD) and glutaraldehyde (GA). The Ag(I) ions were preconcentrated by chemical interaction with bipyridine under a negative potential (−0.6 V); then the reduced ions were oxidized by differential pulse voltammetry and a peak was observed at 0.34 V. The calibration curve was linear in the concentration range from 0.05 μM to 1 μM Ag(I) with a detection limit of 0.025 μM and RSD = 3.6%, for 0.4 μM Ag(I). The presence of several common ions in more than 125-fold excess had no effect on the determination of Ag(I). The developed sensor was applied to the determination of Ag(I) in water samples using a standard addition method

Feeding restriction impairs milk yield and physicochemical properties rendering it less suitable for sale

Feed shortages are relatively frequent in subtropical pasture-based dairy production systems. The effect of feed restriction on milk yield and physical-chemical traits was evaluated in this study. The experiment was carried out in Brazil’s south region. Treatments consisted of control and restricted diet. Six multiparous and six primiparous cows, with 499 ± 47.20 kg body weight (BW), at mid-lactation (188 ± 124 days in milk), producing 19.35 ± 4.10 kg of milk were assigned to two groups, balanced for parity, each group receiving a different sequence of the dietary treatments for 56 days, in a crossover design. Diet nominated as control included 8 kg DM 100 kg BW–1 of Bermuda grass var. Tifton pasture (Cynodon dactylon (L.) Pers.), 5.00 kg of concentrate and 2.50 kg of Tifton hay per day. The restriction diet consisted of 50 % of the quantity offered in the control diet. Milk production and physicochemical composition were evaluated. Feed restriction reduced milk production by 40 %, body condition score by 5 %, milk magnesium by 14.3 %, lactose by 1.7 %, titratable acidity by 10 % and stability to the ethanol test by 9 % and it tended to increase (7 %) milk potassium content. No changes were found for the remaining characteristics. Since feed restriction is quite frequent in Brazil’s extensive dairy production systems, our concern is that besides decreased milk production, changes can occur in the physiochemical attributes of the milk, mainly a reduction in the stability to the ethanol test, which may increase the volume of milk rejected by the industry