Was Einstein Right? Testing Relativity at the Centenary

We review the experimental evidence for Einstein's special and general relativity. A variety of high precision null experiments verify the weak equivalence principle and local Lorentz invariance, while gravitational redshift and other clock experiments support local position invariance. Together these results confirm the Einstein Equivalence Principle which underlies the concept that gravitation is synonymous with spacetime geometry, and must be described by a metric theory. Solar system experiments that test the weak-field, post-Newtonian limit of metric theories strongly favor general relativity. The Binary Pulsar provides tests of gravitational-wave damping and of strong-field general relativity. Recently discovered binary pulsar systems may provide additional tests. Future and ongoing experiments, such as the Gravity Probe B Gyroscope Experiment, satellite tests of the Equivalence principle, and tests of gravity at short distance to look for extra spatial dimensions could constrain extensions of general relativity. Laser interferometric gravitational-wave observatories on Earth and in space may provide new tests of gravitational theory via detailed measurements of the properties of gravitational waves.Comment: 21 pages, 3 figures, to be published in "100 Years of Relativity: Spacetime Structure - Einstein and Beyond", ed. Abhay Ashtekar (World Scientific, Singapore

3D printing scanning electron microscopy sample holders: A quick and cost effective alternative for custom holder fabrication - Fig 6

<p>(a) Representation of a cross section of a nanopipette showing the opening radius and the inner semi cone angle, β. (b) Polarization curves recorded with 5 different nanopipettes in a 0.1 mol L^-1 KCl solution using a pair of AgCl coated silver wires as Quasi-reference counter electrodes (QRCE). Scan rate = 0.1 V s^-1. (c) Transmission-SEM image of a nanopipette. Accelerating voltage = 15 kV.</p

Electrical resistivity measured in 3D printed 1 cm³ test pieces with different infill percentages.

<p>Measurements were taken between different faces of the test cubes.</p

SEM images of nanopipettes and nanoelectrodes.

<p>(a) and (b) top view of a double barrel pipette showing both openings unblocked. (c) Side view of a double barrel pipette. (d) Top view of a dual-function pipette based electrode showing selective carbon deposition in only one barrel. Accelerating voltage = 5 kV.</p

Enhancing the sensitivity towards iodide detection by coupling SECM and an EC catalytic mechanism

In this work, a gold conventional sized electrode (r = 3 mm) and a gold microelectrode (r = 12.5 µm) were employed to investigate the EC’ mechanism involving the anodic oxidation of iodide in the presence of the non-redox-active species thiosulfate. A significant anodic current increase, due to the electrocatalytic process, was noticed in cyclic voltammograms recorded in an iodide solution in the presence of thiosulfate when compared to iodide solution only, at the same experimental conditions. Aiming to enhance the sensitivity of the electroanalytical method towards iodide detection, Scanning Electrochemical Microscopy (SECM) was employed to confine reactants and products in a thin-layer cell defined by the solution region between the microelectrode tip and a Au substrate. Very low iodide concentrations, in the range of a 1–10 µmol/L, can be detected at a short tip-substrate distance, and the method was validated by measuring the analyte content in a synthetic urine sample

Increased sensitivity of ascorbate detection by mediated oxidation in confined electrochemical cells

In this work, the EC’ mechanism involving ascorbate (AA−) and the oxidized form of ferrocenemethanol (FcMeOH) was explored as an analytical strategy to monitor AA− at low concentration levels. The feasibility of this approach was investigated at different mass transport regimes utilizing macro- (glassy carbon) and ultramicroelectrodes (5 μm radius carbon disk). Cyclic voltammograms (CV) were recorded in acetate buffer solution (pH 3.7) using a glassy carbon electrode, and an expressive increase in the anodic peak current (and decrease in the cathodic peak) was noticed in the CV in a solution containing both FcMeOH and ascorbate, confirming the presence of an electrocatalytic process (EC’). The current increase was more pronounced when the reactants and products were confined in a thin solution layer, which was created by approaching an ultramicroelectrode close to an insulator surface. At optimized experimental conditions, a correlation between ascorbate concentration and the steady-state current measured at the ultramicroelectrode was established, allowing the development of an analytical method for ascorbate detection in the micromolar range. The proposed approach was used to quantify ascorbate in a commercial juice sample

Synthesis and characterization of ZrO2/C as electrocatalyst for oxygen reduction to H2O2

Electrogeneration of hydrogen peroxide (H2O2) has potential application in advanced oxidation processes. Amorphous carbon is well known as catalyst for oxygen reduction reaction (ORR) through two-electron pathway. However, modification of the carbon can improve its selectivity for the H2O2 electrogeneration. In the present study, we investigated the properties of ZrO2 nanoparticles supported on carbon black (Printex L6) as electrocatalyst for H2O2 production in acidic medium. The catalytic activity of ZrO2/C for oxygen reduction to H2O2 is higher than the catalytic activity of treated carbon black. The highest selectivity of the ZrO2/C catalyst for H2O2 production is attributable to the presence of oxygenated functional groups on its surface and consequently increase of the surface hydrophilicity in comparison with treated carbon black. This surface effect leads to highest H2O2 electrogeneration, which is shown as a high current efficiency (I(H2O2)%). In fact, increased H2O2 yields from 74.5 to 84.2% were observed for the treated carbon black and ZrO2/C catalysts, respectively, whereas the I(H2O2)% for the unmodified carbon black was 65.3%. Furthermore, the modification of carbon by ZrO2 nanoparticles shifted the ORR half-wave potential towards ca. 137 mV, indicating lower energy consumption for producing H2O2. Thus, the ZrO2/C nanoparticles are shown to be promising electrocatalysts for environmental applications8189195CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQCOORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPESFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP163689/2015-6; 160507/2011-1; 470079/2013-4Não tem2011/14314-1; 2016/01937-

Lucha de clases, guerra civil y genocidio en la Argentina, 1973-1983: Antecedentes, desarrollo, complicidades

Índice Advertencia al lector El colectivo de investigación. Agradecimientos Inés Izaguirre Introducción: El problema y la historia de la investigación Inés Izaguirre PRIMERA PARTE Antecedentes teóricos e históricos Inés Izaguirre SEGUNDA PARTE Formación, desarrollo y derrota de una fuerza revolucionaria en Argentina TERCERA PARTE El embate contra la clase obrera CUARTA PARTE El mapa territorial del genocidio ANEXOs ANEXO DOCUMENTA