1,006 research outputs found

    Risk factors for indeterminate interferon-gamma release assay for the diagnosis of tuberculosis in children : a systematic review and meta-analysis

    Get PDF
    Background: Interferon-gamma release assays (IGRA) are well-established immunodiagnostic tests for tuberculosis (TB) in adults. In children these tests are associated with higher rates of false-negative and indeterminate results. Age is presumed to be one factor influencing cytokine release and therefore test performance.The aim of this study was to systematically review factors associated with indeterminate IGRA results in pediatric patients. Methods: Systematic literature review guided by the preferred reporting items for systematic reviews and meta-analyses (PRISMA) searching PubMed, EMBASE, and Web of Science. Studies reporting results of at least one commercially available IGRA (QuantiFERON-TB, T-SPOT.TB) in pediatric patient groups were included. Random effects meta-analysis was used to assess proportions of indeterminate IGRA results. Heterogeneity was assessed using the I2 value. Risk differences were calculated for studies comparing QuantiFERON-TB and T-SPOT.TB in the same study.Meta-regression was used to further explore the influence of study level variables on heterogeneity. Results: Of 1,293 articles screened, 133 studies were included in the final analysis. These assessed QuantiFERON-TB only in 77.4% (103/133), QuantiFERON-TB and T-SPOT.TB in 15.8% (21/133), and T-SPOT.TB only in 6.8% (9/133) resulting in 155 datasets including 107,418 participants. Overall 4% of IGRA results were indeterminate, and T-SPOT.TB (0.03, 95% CI 0.02-0.05) and QuantiFERON-TB assays (0.05, 95% CI 0.04-0.06) showed similar proportions of indeterminate results; pooled risk difference was – 0.01 (95% CI 0.03-0.00). Significant differences with lower proportions of indeterminate assays with T-SPOT.TB compared to QuantiFERON-TB were only seen in subgroup analyses of studies performed in Africa and in non-HIV-infected immunocompromised patients. Meta-regression confirmed lower proportions of indeterminate results for T-SPOT.TB compared to QuantiFERON-TB only among studies that reported results from non-HIV-infected immunocompromised patients (p < 0.001). Conclusion: On average indeterminate IGRA results occur in 1 in 25 tests performed. Overall, there was no difference in the proportion of indeterminate results between both commercial assays. However, our findings suggest that in patients in Africa and/or patients with immunocompromising conditions other than HIV infection the T-SPOT.TB assay appears to produce fewer indeterminate results

    Reversible Copper Sulfide Conversion in Nonflammable Trimethyl Phosphate Electrolytes for Safe Sodium‐Ion Batteries

    Get PDF
    Rechargeable sodium-ion batteries are considered promising candidates for low-cost and large-scale energy storage systems. However, the limited energy density, cyclability, and safety issues remain challenges for practical applications. Herein, investigation of the Cu1.8S/C composite material as the negative electrode active (conversion) material in combination with a concentrated electrolyte composed of a 3.3 m solution of sodium bis(fluorosulfonyl)imide (NaFSI) in trymethyl phosphate and fluoroethylene carbonate (FEC) as the additive is reported on. Such a combination enables the stable cycling of the conversion-type Cu1.8S/C electrode material for hundreds of cycles with high capacity (380 mAh g−1). Both the salt (NaFSI) and the additive (FEC) contribute to the formation of a stable NaF-rich solid electrolyte interphase (SEI) on the anode surface. A full cell using the Na3V2(PO4)3/C cathode also demonstrates stable cycling performance for 200 cycles with a promising Coulombic efficiency (CE) (99.3%). These findings open new opportunities for the development of safer rechargeable sodium-ion batteries

    Tailoring the Charge/Discharge Potentials and Electrochemical Performance of SnO₂ Lithium‐Ion Anodes by Transition Metal Co‐Doping

    Get PDF
    It has been shown that the introduction of several transition metal (TM) dopants into SnO2 lithium‐ion battery anodes can overcome the issues associated with the irreversible capacity loss from the conversion reaction of SnO2 and the aggregation of the metallic Sn particles formed upon lithiation. As the choice of the single dopant, however, plays a decisive role for the achievable energy density – precisely its redox potential – we investigate herein TM co‐doped SnO2, prepared by using a readily scalable continuous hydrothermal flow synthesis (CHFS) process, to tailor the dis‐/charge profile and by this the energy density. It is shown that the judicious choice of different elemental doping combinations in samples made via CHFS simultaneously improves the cycling performance and the full‐cell energy density. To support these findings, we realized a lithium‐ion full‐cell incorporating the best performing co‐doped SnO2 as negative electrode and high‐voltage LiNi0.5Mn1.5O4 (LNMO) as positive electrode–to the best of our knowledge, the first full‐cell based on such anode material in combination with LNMO as cathode active material

    A new Perspective on the Scalar meson Puzzle, from Spontaneous Chiral Symmetry Breaking Beyond BCS

    Full text link
    We introduce coupled channels of Bethe-Salpeter mesons both in the boundstate equation for mesons and in the mass gap equation for chiral symmetry. Consistency is insured by the Ward Identities for axial currents, which preserve the Goldstone boson nature of the pion and prevents a systematic shift of the hadron spectrum. We study the decay of a scalar meson coupled to a pair of pseudoscalars. We also show that coupled channels reduce the breaking of chiral symmetry, with the same Feynman diagrams that appear in the coupling of a scalar meson to a pair of pseudoscalar mesons. Exact calculations are performed in a particular confining quark model, where we find that the groundstate I=0,3P0qqˉI=0, ^3P_0 q \bar q meson is the f_0(980) with a partial decay width of 40MeV. We also find a 30% reduction of the chiral condensate due to coupled channels.Comment: 17 pages, Revtex, 8 eps figures, and several eps diagrams in equation

    Strange chiral nucleon form factors

    Get PDF
    We investigate the strange electric and magnetic form factors of the nucleon in the framework of heavy baryon chiral perturbation theory to third order in the chiral expansion. All counterterms can be fixed from data. In particular, the two unknown singlet couplings can be deduced from the parity-violating electron scattering experiments performed by the SAMPLE and the HAPPEX collaborations. Within the given uncertainties, our analysis leads to a small and positive electric strangeness radius, =(0.05±0.09)fm2 = (0.05 \pm 0.09) fm^2. We also deduce the consequences for the upcoming MAMI A4 experiment.Comment: 7 pp, REVTeX, uses epsf, minor correction

    Cymantrene–Triazole "Click" Products: Structural Characterization and Electrochemical Properties

    Get PDF
    We report the first known examples of triazole-derivatized cymantrene complexes (η5-[4-substituted triazol-1-yl]cyclopentadienyl)tricarbonylmanganese(I), obtained via a “click” chemical synthesis, bearing a phenyl, 3-aminophenyl, or 4-aminophenyl moiety at the 4-position of the triazole ring. Structural characterization data using multinuclear NMR, UV–vis, ATR-IR, and mass spectrometric methods are provided, as well as crystallographic data for (η5-[4-phenyltriazol-1-yl]cyclopentadienyl)tricarbonylmanganese(I) and (η5-[4-(3-aminophenyl)triazol-1-yl]cyclopentadienyl)tricarbonylmanganese(I). Cyclic voltammetric characterization of the redox behavior of each of the three cymantrene–triazole complexes is presented together with digital simulations, in situ infrared spectroelectrochemistry, and DFT calculations to extract the associated kinetic and thermodynamic parameters. The trypanocidal activity of each cymantrene–triazole complex is also examined, and these complexes are found to be more active than cymantrene alone

    REAL-TIME DESCRIPTION OF PARTON-HADRON CONVERSION AND CONFINEMENT DYNAMICS

    Get PDF
    We propose a new and universal approach to the hadronization problem that incorporates both partonic and hadronic degrees of freedom in their respective domains of relevance, and that describes the conversion between them within a kinetic field theory formulation in real time and full 7-dimensional phase space. We construct a scale-dependent effective theory that reduces to perturbative QCD with its scale and chiral symmetry properties at short space-time distances, but at large distances (r > 1 fm) yields symmetry breaking gluon and quark condensates plus hadronic excitations. The approach is applied to the evolution of fragmenting qq~ and gg jet pairs as the system evolves from the initial 2-jet configuration, via parton showering and cluster formation, to the final yield of hadrons. The phenomenological implications for e+e- -> hadrons are investigated, such as the time scale of the transition, and its energy dependence, cluster size and mass distributions. We compare our results for particle production and Bose-Einstein correlations with experimental data, and find an interesting possibility of extracting the basic parameters of the space-time evolution of the system from Bose enhancement measurements.Comment: 51 pages, latex, 14 figures as uu-encoded postscript file

    Toward the Potential Scale-Up of Sn0.9_{0.9}Mn0.1_{0.1}O2_{2}||LiNi0.6_{0.6}Mn0.2_{0.2}Co0.2_{0.2}O2_{2} Li-Ion Batteries – Powering a RemoteControlled Vehicle and Life Cycle Assessment

    Get PDF
    Academic research in the battery field frequently remains limited to small coin or pouch cells, especially for new materials that are still rather far from commercialization, which renders a meaningful evaluation at an early stage of development challenging. Here, the realization of large lab-scale pouch cells comprising Sn0.9_{0.9}Mn0.1_{0.1}O2_{2} (SMO), prepared via an easily scalable hydrothermal synthesis method, as an alternative active material for the negative electrode and LiNi0.6_{0.6}Mn0.2_{0.2}Co0.2_{0.2}O2_{2} (NMC622_{622}) as a commercially available active material for the positive electrode is reported. Nine double-layer pouch cells are connected in series and parallel, suitable for powering a remote-controlled vehicle. Subsequently, these SMO‖NMC622_{622} cells are critically evaluated by means of an early-stage life cycle assessment and compared to graphite‖NMC622_{622} cells, in order to get first insights into the potential advantages and challenges of such lithium-ion chemistry
    • 

    corecore