Effect of acid oxidation treatment on adsorption properties of arc-discharge synthesized multiwall carbon nanotubes

The effect of nitric/sulfuric acid oxidation treatment on commercial arc-discharge multiwall carbon nanotubes was studied. Purification and structure modifications were assessed via Transmission Electron Microscopy and Thermogravimetric Analysis; while changes in adsorption properties were monitored by nitrogen and methane adsorption isotherms. After treatment, nitrogen isotherms present hysteresis loop and an increased BET surface area; while adsorption energies obtained from isosteric heat profiles revealed a marked decrease. We propose an explanation for these findings and use macroscopic experimental data to gain insight on acid oxidation effect on the material.Se estudió el efecto de la oxidación ácida por medio de mezclas sulfúrico/nítrico, de nanotubos comerciales de pared múltiple sintetizados por el método de la descarga de arco. Para evaluar el grado de pureza y las modificaciones estructurales se utilizaron las técnicas de Microscopía Electrónica de Transmisión y Termogravimetría; mientras que los cambios en las propiedades de adsorción fueron monitoreados por medio de la realización de isotermas a distintas temperaturas utilizando gases simples como Nitrógeno y Metano. Luego del tratamiento oxidativo, se observó la aparición de ciclos de histéresis en las isotermas al mismo tiempo que el área superficial según BET se incrementó. Por otro lado, los calores isostéricos obtenidos evidenciaron una disminución importante. Proponemos una explicación posible para estos hallazgos y hacemos uso de la información experimental obtenida para revelar detalles del mecanismo de oxidación de los Nanotubos.Instituto de Investigaciones Fisicoquímicas Teóricas y AplicadasCentro de Química Inorgánic

Effect of acid oxidation treatment on adsorption properties of arc-discharge synthesized multiwall carbon nanotubes

The effect of nitric/sulfuric acid oxidation treatment on commercial arc-discharge multiwall carbon nanotubes was studied. Purification and structure modifications were assessed via Transmission Electron Microscopy and Thermogravimetric Analysis; while changes in adsorption properties were monitored by nitrogen and methane adsorption isotherms. After treatment, nitrogen isotherms present hysteresis loop and an increased BET surface area; while adsorption energies obtained from isosteric heat profiles revealed a marked decrease. We propose an explanation for these findings and use macroscopic experimental data to gain insight on acid oxidation effect on the material.Se estudió el efecto de la oxidación ácida por medio de mezclas sulfúrico/nítrico, de nanotubos comerciales de pared múltiple sintetizados por el método de la descarga de arco. Para evaluar el grado de pureza y las modificaciones estructurales se utilizaron las técnicas de Microscopía Electrónica de Transmisión y Termogravimetría; mientras que los cambios en las propiedades de adsorción fueron monitoreados por medio de la realización de isotermas a distintas temperaturas utilizando gases simples como Nitrógeno y Metano. Luego del tratamiento oxidativo, se observó la aparición de ciclos de histéresis en las isotermas al mismo tiempo que el área superficial según BET se incrementó. Por otro lado, los calores isostéricos obtenidos evidenciaron una disminución importante. Proponemos una explicación posible para estos hallazgos y hacemos uso de la información experimental obtenida para revelar detalles del mecanismo de oxidación de los Nanotubos.Instituto de Investigaciones Fisicoquímicas Teóricas y AplicadasCentro de Química Inorgánic

Diets containing sea cucumber (Isostichopus badionotus) meals are hypocholesterolemic in young rats

Peer reviewedPublisher PD

Relationships between heavy metal concentrations in three different body fluids and male reproductive parameters: a pilot study

<p>Abstract</p> <p>Background</p> <p>Animal studies have shown the reproductive toxicity of a number of heavy metals. Very few human observational studies have analyzed the relationship between male reproductive function and heavy metal concentrations in diverse biological fluids.</p> <p>Methods</p> <p>The current study assessed the associations between seminal and hormonal parameters and the concentration of the 3 most frequent heavy metal toxicants (lead, cadmium and mercury) in three different body fluids. Sixty one men attending infertility clinics that participated in a case-control study to explore the role of environmental toxins and lifestyles on male infertility were analyzed. Concentration of lead, cadmium and mercury were measured in blood and seminal plasma and whole blood using anodic stripping voltammetry and atomic absorption spectrophotometry. Serum samples were analyzed for follicle-stimulating hormone, luteinizing hormone and testosterone. Semen analyses were performed according to World Health Organization criteria. Mann-Whitney test and Spearman's rank correlations were used for unadjusted analyses. Multiple linear regression models were performed controlling for age, body mass index and number of cigarettes per day.</p> <p>Results</p> <p>There were no significant differences between cases and controls in the concentrations of heavy metals in any of the three body fluids. In multivariate analyses using all subjects no significant associations were found between serum hormone levels and metal concentrations. However there was a significant positive association between the percentage of immotile sperms and seminal plasma levels of lead and cadmium.</p> <p>Conclusions</p> <p>Our results suggest that the presence of lead and cadmium in the reproductive tract of men may be related to a moderate alteration of their seminal parameters.</p

Balance de energía, nitrógeno y fósforo en sistemas de ceba bovina en pastoreo

Objective: The aim of this work was to perform balances of energy, nitrogen, and phosphorus in pre-fattening and fattening bovine systems at Turiguanó Livestock Breeding Company, in the province of Ciego de Ávila, Cuba. Materials and methods: The botanical composition of the farms evaluated was determined, and energy, nitrogen, and phosphorus balances were performed. Results: The annual energy, nitrogen, and phosphorus balances were negative on the farms in the study. Conclusions: New strategies are required to enhance energy and nutrient (nitrogen and phosphorus) use to increase beef production during the final stage. Accordingly, improvements in recycling, balance, and efficiency in the use of energy and these minerals are linked to increases in live weight/day, and better final weights for the industry during that stage.Objetivo: Realizar el balance de energía, nitrógeno y fósforo de sistemas de ceba inicial y ceba final bovina en la Empresa Pecuaria Genética Turiguanó en la provincia Ciego de Ávila en Cuba. Materiales y métodos: Se determinó la composición botánica en las unidades evaluadas y se realizaron los balances de energía, nitrógeno y fósforo. Resultados: Las unidades estudiadas presentaron balances negativos anuales en lo energético y en el nitrógeno y fósforo. Conclusiones: Son necesarias estrategias para aumentar el aprovechamiento de energía y los nutrientes como nitrógeno y fósforo e incrementar la producción bovina de carne en su fase final, por lo que las mejoras del reciclaje, el balance y la eficiencia de utilización de la energía y estos minerales, están ligadas a los incrementos en peso vivo/día y a mejores pesos finales a industria en esta fase

Standalone vertex finding in the ATLAS muon spectrometer

A dedicated reconstruction algorithm to find decay vertices in the ATLAS muon spectrometer is presented. The algorithm searches the region just upstream of or inside the muon spectrometer volume for multi-particle vertices that originate from the decay of particles with long decay paths. The performance of the algorithm is evaluated using both a sample of simulated Higgs boson events, in which the Higgs boson decays to long-lived neutral particles that in turn decay to bbar b final states, and pp collision data at √s = 7 TeV collected with the ATLAS detector at the LHC during 2011

Measurements of Higgs boson production and couplings in diboson final states with the ATLAS detector at the LHC

Measurements are presented of production properties and couplings of the recently discovered Higgs boson using the decays into boson pairs, H →γ γ, H → Z Z∗ →4l and H →W W∗ →lνlν. The results are based on the complete pp collision data sample recorded by the ATLAS experiment at the CERN Large Hadron Collider at centre-of-mass energies of √s = 7 TeV and √s = 8 TeV, corresponding to an integrated luminosity of about 25 fb−1. Evidence for Higgs boson production through vector-boson fusion is reported. Results of combined fits probing Higgs boson couplings to fermions and bosons, as well as anomalous contributions to loop-induced production and decay modes, are presented. All measurements are consistent with expectations for the Standard Model Higgs boson

Measurement of the top quark pair cross section with ATLAS in pp collisions at √s=7 TeV using final states with an electron or a muon and a hadronically decaying τ lepton

A measurement of the cross section of top quark pair production in proton-proton collisions recorded with the ATLAS detector at the Large Hadron Collider at a centre-of-mass energy of 7 TeV is reported. The data sample used corresponds to an integrated luminosity of 2.05 fb -1. Events with an isolated electron or muon and a τ lepton decaying hadronically are used. In addition, a large missing transverse momentum and two or more energetic jets are required. At least one of the jets must be identified as originating from a b quark. The measured cross section, σtt-=186±13(stat.)±20(syst.)±7(lumi.) pb, is in good agreement with the Standard Model prediction