Ultrahard carbon film from epitaxial two-layer graphene

Atomically thin graphene exhibits fascinating mechanical properties, although its hardness and transverse stiffness are inferior to those of diamond. To date, there hasn't been any practical demonstration of the transformation of multi-layer graphene into diamond-like ultra-hard structures. Here we show that at room temperature and after nano-indentation, two-layer graphene on SiC(0001) exhibits a transverse stiffness and hardness comparable to diamond, resisting to perforation with a diamond indenter, and showing a reversible drop in electrical conductivity upon indentation. Density functional theory calculations suggest that upon compression, the two-layer graphene film transforms into a diamond-like film, producing both elastic deformations and sp2-to-sp3 chemical changes. Experiments and calculations show that this reversible phase change is not observed for a single buffer layer on SiC or graphene films thicker than 3 to 5 layers. Indeed, calculations show that whereas in two-layer graphene layer-stacking configuration controls the conformation of the diamond-like film, in a multilayer film it hinders the phase transformation.Comment: Published online on Nature Nanotechnology on December 18, 201

The Impact of HIV Infection and CD4 Cell Count on the Performance of an Interferon Gamma Release Assay in Patients with Pulmonary Tuberculosis

BACKGROUND:The performance of the tuberculosis specific Interferon Gamma Release Assays (IGRAs) has not been sufficiently documented in tuberculosis- and HIV-endemic settings. This study evaluated the sensitivity of the QuantiFERON TB-Gold In-Tube (QFT-IT) in patients with culture confirmed pulmonary tuberculosis (PTB) in a TB- and HIV-endemic population and the effect of HIV-infection and CD4 cell count on test performance. METHODOLOGY/PRINCIPAL FINDINGS:161 patients with sputum culture confirmed PTB were subjected to HIV- and QFT-IT testing and measurement of CD4 cell count. The QFT-IT was positive in 74% (119/161; 95% CI: 67-81%). Sensitivity was higher in HIV-negative (75/93) than in HIV-positive (44/68) patients (81% vs. 65%, p = 0.02) and increased with CD4 cell count in HIV-positive patients (test for trend p = 0.03). 23 patients (14%) had an indeterminate result and this proportion decreased with increasing CD4 cell count in HIV-positive patients (test for trend p = 0.03). Low CD4 cell count (<300 cells/microl) did not account for all QFT-IT indeterminate nor all negative results. Sensitivity when excluding indeterminate results was 86% (95% CI: 81-92%) and did not differ between HIV-negative and HIV-positive patients (88 vs. 83%, p = 0.39). CONCLUSIONS/SIGNIFICANCE:Sensitivity of the QFT-IT for diagnosing active PTB infection was reasonable when excluding indeterminate results and in HIV-negative patients. However, since the test missed more than 10% of patients, its potential as a rule-out test for active TB disease is limited. Furthermore, test performance is impaired by low CD4 cell count in HIV-positive patients and possibly by other factors as well in both HIV-positive and HIV-negative patients. This might limit the potential of the test in populations where HIV-infection is prevalent

The burden and treatment of HIV in tuberculosis patients in Papua Province, Indonesia: a prospective observational study

<p>Abstract</p> <p>Background</p> <p>New diagnoses of tuberculosis (TB) present important opportunities to detect and treat HIV. Rates of HIV and TB in Indonesia's easternmost Papua Province exceed national figures, but data on co-infection rates and outcomes are lacking. We aimed to measure TB-HIV co-infection rates, examine longitudinal trends, compare management with World Health Organisation (WHO) recommendations, and document progress and outcome.</p> <p>Methods</p> <p>Adults with newly-diagnosed smear-positive pulmonary TB managed at the Timika TB clinic, Papua Province, were offered voluntary counselling and testing for HIV in accordance with Indonesian National Guidelines, using a point-of-care antibody test. Positive tests were confirmed with 2 further rapid tests. Study participants were assessed using clinical, bacteriological, functional and radiological measures and followed up for 6 months.</p> <p>Results</p> <p>Of 162 participants, HIV status was determined in 138 (85.2%), of whom 18 (13.0%) were HIV+. Indigenous Papuans were significantly more likely to be HIV+ than Non-Papuans (Odds Ratio [OR] 4.42, 95% confidence interval [CI] 1.38-14.23). HIV prevalence among people with TB was significantly higher than during a 2003-4 survey at the same TB clinic, and substantially higher than the Indonesian national estimate of 3%. Compared with HIV- study participants, those with TB-HIV co-infection had significantly lower exercise tolerance (median difference in 6-minute walk test: 25 m, p = 0.04), haemoglobin (mean difference: 1.3 g/dL, p = 0.002), and likelihood of cavitary disease (OR 0.35, 95% CI 0.12-1.01), and increased occurrence of pleural effusion (OR 3.60, 95% CI 1.70-7.58), higher rates of hospitalisation or death (OR 11.80, 95% CI 1.82-76.43), but no difference in the likelihood of successful 6-month treatment outcome. Adherence to WHO guidelines was limited by the absence of integration of TB and HIV services, specifically, with no on-site ART prescriber available. Only six people had CD4+ T-cell counts recorded, 11 were prescribed co-trimoxazole and 4 received ART before, during or after TB treatment, despite ART being indicated in 14 according to 2006 WHO guidelines.</p> <p>Conclusions</p> <p>TB-HIV co-infection in southern Papua, Indonesia, is a serious emerging problem especially among the Indigenous population, and has risen rapidly in the last 5 years. Major efforts are required to incorporate new WHO recommendations on TB-HIV management into national guidelines, and support their implementation in community settings.</p

Updating the approaches to define susceptibility and resistance to anti-tuberculosis agents: implications for diagnosis and treatment

11 páginas, 2 figuras, 1 tablaInappropriately high breakpoints have resulted in systematic false-susceptible AST results to anti-TB drugs. MIC, PK/PD and clinical outcome data should be combined when setting breakpoints to minimise the emergence and spread of antimicrobial resistance.I. Comas was supported by PID2019-104477RB-I00 from the Spanish Science Ministry and by ERC (CoG 101001038)Peer reviewe

Don Simplici Mala Sombra : sarsuela catalana en un acte y en vers [Ms. 1208]

22 f. ; 18 cm. — Còpia de representació. — Núm. 061, a la port. — A l'interior de la coberta, menció dels drets d'autor. — F. 1-22. — Acotacions de l'autor en lletra més petita i entre parèntesis. — Text a dues tintes: marró, per als diàlegs, i lila, per al text per a ser cantat de la part musical

Synthesis and cytotoxicity analysis of porous β-TCP/starch bioceramics

The production of porous ceramics for biomedical applications is widely available in the Ceramics industry. In bioceramic applications, interconnected pores are pertinent to increase osteoconductivity and cell proliferation. However, an increase in pore size and the pore amount decrease the mechanical properties. For this reason, pore properties must be precisely controlled. In this study, the effect of a natural pore-forming agent, corn starch addition, and sintering conditions on mechanical properties and biocompatibility was investigated. During mixing, four different starch amounts (1, 3, 5, and 10 wt%) were added to pure beta-tricalcium phosphate (β-TCP) ceramic powders and pressed. Pressed pellets were sintered at 1000, 1100, 1200, and 1300 °C. A scanning electron microscope (SEM) is used to investigate microstructure, texture, pore size, and cell adhesion. The mechanical properties of the β-TCP ceramic parts were further characterized by measuring the density and compressive strength. Cytotoxicity tests were carried out with MTT assays. The optimum mechanical properties were obtained at 1100 °C sintered biocomposites. Although starch starts to burn around 410 °C and analytical results show no presence of starch after the sintering process, biocomposites initially containing 10% starch showed improved cell proliferation. However, a reduction of 59% in compressive strength and a 16% reduction in the density were also recorded. It was observed that 10 wt% starch addition increases cell proliferation by 10% in sintered β-TCP samples. Starch powder additions can be used to increase the cell viability of the material by facilitating the creation of pores, as a low-cost pore-forming agent for porous bone graft and non-load-bearing material in both orthopaedics and maxillofacial applications. Graphical abstract: [Figure not available: see fulltext.