Prevalence of Vibrio cholerae O1 serogroup in Assam, India: A hospital-based study

Background & objectives: Although cholera remains to be an important public health problem, studies on reliable population-based estimates of laboratory confirmed cholera in endemic areas are limited worldwide. The aim of this hospital-based study was to evaluate the prevalence of Vibrio cholerae serogroup in Assam, India, during 2003-2013. Methods: Stool samples/rectal swabs were collected from acute watery diarrhoea (AWD) cases during 2003-2013 and processed by standard microbiological procedures. Antibiotic sensitivity test was done following the Clinical and Laboratory Standards Institute guidelines. Year-wise epidemiological trend of cholera was analyzed. Results: Cholera contributed to 3.93 per cent of AWD cases. In Assam, cholera was found to be more prevalent in the rural areas (6.7%) followed by the tea gardens (5.06%), urban slum (1.9%) and urban areas (1.4%). Highest proportion of cholera (13.7%) was observed in 0-10 yr age group. Of them, 11.5 per cent belonged to 0-5 yr age group. V. cholerae O1 El Tor serotype Ogawa was the predominant isolate. Multiple drug-resistant isolates of V. cholerae O1 Ogawa were reported in the study. Interpretation & conclusions: Emergence of resistance amongst V. cholerae towards many antibiotics is a matter of concern. Hence, continuous surveillance for diarrhoeal disorders is necessary to control the future outbreaks of cholera in this region

SnO₂ Quantum Dots-Reduced Graphene Oxide Composite for Enzyme-Free Ultrasensitive Electrochemical Detection of Urea

Most of the urea sensors are biosensors and utilize urease, which limit their use in harsh environments. Recently, because of their exceptional ability to endorse faster electron transfer, carbonaceous material composites and quantum dots are being used for fabrication of a sensitive transducer surface for urea biosensors. We demonstrate an enzyme free ultrasensitive urea sensor fabricated using a SnO₂ quantum dots (QDs)/reduced graphene oxide (RGO) composite. Due to the synergistic effect of the constituents, the SnO₂ QDs/RGO (SRGO) composite proved to be an excellent probe for electrochemical sensing. The morphology and structure of the composite was characterized by various techniques, and it was observed that SnO₂ QDs are decorated on RGO layers. Electrochemical studies were performed to evaluate the characteristics of the sensor toward detection of urea. Amperometry studies show that the SRGO/GCE electrode is sensitive to urea in the concentration range of 1.6 × 10^–14–3.9 × 10^–12 M, with a detection limit of as low as 11.7 fM. However, this is an indirect measurement for urea wherein the analytical signal is recorded as a decrease in the amperommetric and/or voltammetric current from the solution redox species ferrocyanide. The porous structure of the SRGO matrix offers a very low transport barrier and thus promotes rapid diffusion of the ionic species from the solution to the electrode, leading to a rapid response time (∼5 s) and ultrahigh sensitivity (1.38 μA/fM). Good analytical performance in the presence of interfering agents, low cost, and easy synthesis methodology suggest that SRGO can be quite promising as an electroactive material for effective urea sensing

Carbon–Manganese Oxide Composite Derived from Wheat Flour: Kitchen-Inspired Green Synthesis and Applications in Energy Storage

The quest for better alternatives for graphite anodes is the holy grail in the field of energy storage technologies. Biomass-derived carbon has been widely explored as the energy-dense and cost-effective option but involves several pre/post-conditioning steps. In this study, kitchen chemistry concepts of fermentation have been utilized to obtain sustainable carbon anodes from readily available and cost-effective wheat flour and baker’s yeast. The yeast-fermented mixture of wheat flour and MnCO3 is pyrolyzed under 500 °C to yield porous C-MnO composites, which have been explored as an anode for Li-ion batteries. The material showed superior electrochemical performance with an initial discharge of 1160 mAh g–1 at 0.15 A g–1 (after solid electrolyte interface formation). A reversible capacity of 1499 mAh g–1 was obtained with a concomitant improvement of 30% after 160 cycles exhibiting a “negative fading effect”. Excellent electrochemical behavior has been attributed to the synergistic effect of in situ synthesized, well-dispersed MnO in carbon, the presence of redox-active Mn, and well-connected porosity in nanohybrids. At a high current density of 1 A g–1, the anode displayed an exemplary initial discharge capacity of 770 mAh g–1 with a high initial Coulombic efficiency of 90%, which was maintained at 856 mAh g–1 after 760 cycles. Easy synthesis and excellent electrochemical performance render this material highly promising for battery applications