Single-step ambient-air synthesis of graphene from renewable precursors as electrochemical genosensor

©The Author(s) 2017. Thermal chemical vapour deposition techniques for graphene fabrication, while promising, are thus far limited by resource-consuming and energy-intensive principles. In particular, purified gases and extensive vacuum processing are necessary for creating a highly controlled environment, isolated from ambient air, to enable the growth of graphene films. Here we exploit the ambient-air environment to enable the growth of graphene films, without the need for compressed gases. A renewable natural precursor, soybean oil, is transformed into continuous graphene films, composed of single-to-few layers, in a single step. The enabling parameters for controlled synthesis and tailored properties of the graphene film are discussed, and a mechanism for the ambient-air growth is proposed. Furthermore, the functionality of the graphene is demonstrated through direct utilization as an electrode to realize an effective electrochemical genosensor. Our method is applicable to other types of renewable precursors and may open a new avenue for low-cost synthesis of graphene films

Retention of Re in metakaolin based geopolymer in the presence of an organic reductant – an experimental study

The goal of this research was to examine the change in redox sensitive contaminant retention and leaching behavior from a model geopolymer system, during oxidation and carbonation, in the presence of an organic reductant. The behavior of redox sensitive elements under variable environmental conditions is specifically important for understanding the leaching of radionuclides retained in geopolymeric materials (e.g. Tc) that are soluble when oxidized and insoluble under reducing conditions. An alkali-activated metakaolin geopolymer with high silica/alumina ratio was selected as a model material. Rhenium was selected as the model redox sensitive element, which exhibits a large valence (-3 to +7) and solubility range. Rhenium was introduced in its most oxidized form (VII) as Re2S7. Ascorbic acid was used as a reducing agent during geopolymer casting due to its high solubility and homogeneous distribution within the matrix. Cylindrical monoliths were cured for 90 days under an inert atmosphere (N2) and then aged for 60 days under 98% N2 + 2% CO2 or CO2 deficient air, at a constant relative humidity (68%). The samples were then subjected to EPA 1313 pH dependent leaching test and EPA 1315 monolith leaching test. Leachates were analyzed using DOC and ICP techniques. XRD and SEM – EDS imaging and analyses were used to characterizes the solids Results show that Re has precipitated as ReS2 (IV) in the matrix. The pH dependent leaching test show that Re was released homogenously throughout most of the pH range (3-12). However, the retention of the material aged under CO2 deficient air was three times lower, indicating that the main effect on leaching from this material is of the oxidation process. The natural pH values were 11.3 and 12 for the material aged under 2% CO2 and for material aged under CO2 deficient air respectively, indicating minor carbonation in the former, however, no carbonate minerals were detected in the matrix. Monolith leaching results show that the geopolymers aged under CO2 deficient air have retained significantly less Re (0.24% leaching) relative to the sample aged under 2% CO2 (0.07wt % leaching). -log(diffusivity) values were in the order of 15 and 16 for CO2 deficient air and 2% CO2 respectively. There is a clear positive correlation between the amount of Re and DOC released from the samples, where their amounts are significantly larger for the samples aged under CO2 deficient air, indicating that the main Re-release mechanism from these samples is related to chelation to organic species under oxidizing conditions

En reconstruction mammaire : intérêt du dépistage du portage de Staphylococcus aureus dans la prévention de l’infection du site opératoire

National audienceThe incidence of prosthesis infections after breast reconstruction is of the order of 4% to 13% according to the literature. In surgical patients, Staphylococcus aureus (S. aureus) is the bacterial species most often responsible for surgical site infections. In cardiac surgery, screening for carriage of S. aureus and preoperative decontamination are carried out routinely before prosthetic surgery. We retrospectively reviewed data from patients at our institution between January 2011 and December 2013. Our series showed that the prosthesis infection rates were in the range of 5.92% in 2008 with an ISO rate of S. aureus 3.61%. Routine screening for prosthetic reconstructions was performed to assess the impact of preoperative decontamination patients in carriers of S. aureus. This screening was done in 381 patients: 17.8% of patients were carriers of S. aureus ; 11 patients have an ISO (or an incidence rate of 2.88%) ; 5 patients have an ISO S. aureus (an incidence of S. aureus ISO 1.3%). The introduction of the screening process, allowed a drop of 5.92% ISO rate at 1.46% with a passage of S. aureus SSI rates of 3, 60% to 0.72%. In the near future, studies are needed to confirm these encouraging results, to demonstrate the efficacy of preoperative decontamination in carriers of S. aureus patients before laying prosthesis

HIV Self-testing and the Missing Linkage

Rochelle Walensky and Ingrid Bassett discuss new research in <I>PLoS Medicine</I> that assessed the feasibility of home-based oral HIV self-testing in Malawi, and suggest that linkage to care must be demonstrated before the success of oral self-testing can be determined

Search for dark matter produced in association with heavy-flavor quark pairs in proton-proton collisions at √s = 13 TeV

A search is presented for an excess of events with heavy-flavor quark pairs (tt and bb) and a large imbalance in transverse momentum in data from proton–proton collisions at a center-of-mass energy of 13 TeV. The data correspond to an integrated luminosity of 2.2fb^(−1) collected with the CMS detector at the CERN LHC. No deviations are observed with respect to standard model predictions. The results are used in the first interpretation of dark matter production in tt and bb final states in a simplified model. This analysis is also the first to perform a statistical combination of searches for dark matter produced with different heavy-flavor final states. The combination provides exclusions that are stronger than those achieved with individual heavy-flavor final states

Measurement of the B^± Meson Nuclear Modification Factor in Pb-Pb Collisions at √S_(NN) = 5.02 TeV

The differential production cross sections of B^± mesons are measured via the exclusive decay channels B^± → J/ψK^ ±→ μ^+μ^−K^± as a function of transverse momentum in pp and Pb-Pb collisions at a center-of-mass energy √S_(NN) = 5.02  TeV per nucleon pair with the CMS detector at the LHC. The pp(Pb-Pb) data set used for this analysis corresponds to an integrated luminosity of 28.0  pb^(-1) (351  μb^(-1)). The measurement is performed in the B^± meson transverse momentum range of 7 to 50  GeV/c, in the rapidity interval |y| < 2.4. In this kinematic range, a strong suppression of the production cross section by about a factor of 2 is observed in the Pb-Pb system in comparison to the expectation from pp reference data. These results are found to be roughly compatible with theoretical calculations incorporating beauty quark diffusion and energy loss in a quark-gluon plasma

Les Houches 2015: Physics at TeV Colliders Standard Model Working Group Report

This Report summarizes the proceedings of the 2015 Les Houches workshop on Physics at TeV Colliders. Session 1 dealt with (I) new developments relevant for high precision Standard Model calculations, (II) the new PDF4LHC parton distributions, (III) issues in the theoretical description of the production of Standard Model Higgs bosons and how to relate experimental measurements, (IV) a host of phenomenological studies essential for comparing LHC data from Run I with theoretical predictions and projections for future measurements in Run II, and (V) new developments in Monte Carlo event generators.Comment: Proceedings of the Standard Model Working Group of the 2015 Les Houches Workshop, Physics at TeV Colliders, Les Houches 1-19 June 2015. 227 page

Constraints on the double-parton scattering cross section from same-sign W boson pair production in proton-proton collisions at √s = 8 TeV

A first search for same-sign WW production via double-parton scattering is performed based on proton-proton collision data at a center-of-mass energy of 8 TeV using dimuon and electron-muon final states. The search is based on the analysis of data corresponding to an integrated luminosity of 19.7 fb^(−1). No significant excess of events is observed above the expected single-parton scattering yields. A 95% confidence level upper limit of 0.32 pb is set on the inclusive cross section for same-sign WW production via the double-parton scattering process. This upper limit is used to place a 95% confidence level lower limit of 12.2 mb on the effective double-parton cross section parameter, closely related to the transverse distribution of partons in the proton. This limit on the effective cross section is consistent with previous measurements as well as with Monte Carlo event generator predictions