Background: Bacteriologically-confirmed tuberculosis (TB) cases used in calculating TB prevalence in a country are obtained through laboratory examination of sputum specimens. Objective: This article describes laborat...
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Background: Bacteriologically-confirmed tuberculosis (TB) cases used in calculating TB prevalence in a country are obtained through laboratory examination of sputum specimens. Objective: This article describes laboratory processing of specimens, results overview, conclusions and key lessons learnt from the perspective of laboratory personnel involved in the conduct of TB disease prevalence survey in Ghana in 2013. Methods: Symptoms screening and Chest X-ray suggestive of TB were used to select participants who produced sputum to confirm TB cases using microscopy, culture and Xpert®MTB/RIF assay (GeneXpert). Results: A total of 15,935 single and paired sputum specimens were received from eligible participants. About half of Ziehl-Nielsen (129/263) and Auramine O (122/246) stained smear positives were scanty positive. Culture positivity rate for Mycobacterium tuberculosis complex was 266/14,994 (1.7%) and 100/15,179 (0.7%) in Mycobacterial Growth Indicator Tube (MGIT) and Lowenstein-Jensen (LJ) media respectively;while non-tuberculous mycobacterium was 294/14,994 (1.96%) and 167/15,179 (1.1%). Total contamination rates in MGIT (5.4%) were higher than in LJ (1.7%). Prevalence of smear positive TB and bacteriologically confirmed TB among adult population (≥15 years) was estimated at 111 (95% CI: 76 - 145) and 356 (95% CI: 288 - 425) per 100,000 population respectively. Conclusions and Lessons Learnt: Direct supervision of specimen collection by well-trained laboratory personnel, timely transportation of specimens from field to laboratory, prompt specimen processing and use of electronic data management systems are essential for a reliable TB disease prevalence survey data. More importantly, strengthening human and logistical capacity of the laboratory must be of utmost priority.
We report a novel chemical vapor deposition (CVD) based strategy to synthesize carbon-coated Fe203 nanoparticles dispersed on graphene sheets (Fe2Og@C@G). Graphene sheets with high surface area and aspect ratio ar...
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We report a novel chemical vapor deposition (CVD) based strategy to synthesize carbon-coated Fe203 nanoparticles dispersed on graphene sheets (Fe2Og@C@G). Graphene sheets with high surface area and aspect ratio are chosen as space restrictor to prevent the sintering and aggregation of nanoparticles during high temperature treatments (800 ℃). In the resulting nanocomposite, each individual Fe2O3 nanoparticle (5 to 20 nm in diameter) is uniformly coated with a continuous and thin (two to five layers) graphitic carbon shell. Further, the core-shell nanoparticles are evenly distributed on graphene sheets. When used as anode materials for lithium ion batteries, the conductive-additive-free Fe2OB@C@G electrode shows outstanding Li+ storage properties with large reversible specific capacity (864 mah/g after 100 cycles), excellent cyclic stability (120% retention after 100 cycles at 100 mA/g), high Coulombic efficiency (-99%), and good rate capability.
Carbonate electrolytes are one of the most desirable electrolytes for high-energy lithium-sulfur batteries(LSBs)because of their successful implementation in commercial Li-ion *** low-polysulfide-solubility feature of...
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Carbonate electrolytes are one of the most desirable electrolytes for high-energy lithium-sulfur batteries(LSBs)because of their successful implementation in commercial Li-ion *** low-polysulfide-solubility feature of some carbonate solvents also makes them very promising for overcoming the shuttle effects of ***,regular sulfur electrodes experience undesired electrochemical mechanisms in carbonate electrolytes due to side *** this study,we report a catalytic redox mechanism of sulfur in propylene carbonate(PC)electrolyte based on a compari-son *** catalytic mechanism is characterized by the interactions between polysulfides and dual N/O functional groups on the host carbon,which largely prevents side reactions between polysulfides and the carbonate *** a mechanism coupled with the low-polysulfide-solubility feature leads to stable cycling of LSBs in PC *** dual N/O functional groups are identified via a density functional theory *** work provides an alternative route for enabling LSBs in carbonate electrolytes.
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