Sol-gel based simonkolleite nanopetals with SnO2 nanoparticles in graphite-like amorphous carbon as an efficient and reusable photocatalyst

We report a new sol-gel nanocomposite (STC) having simonkolleite nanopetals (SC) and quasi-spherical tin oxide (SO) nanoparticles embedded in graphite-like amorphous carbon (C) as an efficient and reusable photocatalyst for the degradation of rhodamine 6G dye under UV (254 nm) illumination. The STC was synthesized using vacuum curing (450 degrees C) of precursor gel derived from a sol (Zn : Sn, 2 : 1) in 2-methoxyethanol with acetylacetone. The presence of tetragonal SO well decorated on rhombohedral SC forming nanoheterostructures in the carbon matrix was identified by X-ray diffraction, micro-Raman and X-ray photoelectron spectroscopy and electron microscopes (field emission scanning electron and transmission electron) studies. Carbon content and thermal weight loss behaviour in STC were studied by carbon determinator and thermogravimetry. The nanocomposite showed high photocatalytic activity (10(-5) M dye solution degraded completely in 32 min). Reusability test of the photocatalyst exhibited about 95% of dye degradation after five successive recycles. In addition to accelerating photo-induced charge carrier separation and electron transport in the nanoheterostructures as revealed from electrochemical impedance spectroscopy response of the UV-exposed nanocomposite, an active role of the carbon at an optimum content (similar to 18%) was found for generating high BET specific surface area (similar to 143 m(2) g(-1)). This simple synthesis strategy could open a new avenue to the development of sol-gel nanocomposites as efficient and reusable photocatalysts from various simonkolleite-based metal oxide semiconductors embedded in graphite-like amorphous carbon

Effect of Ga doping on Microstructural, Optical and Photocatalytic Properties of Nanostructured Zinc Oxide Thin Films

Ga doped nanostructured zinc oxide thin films (thickness, 160-170 nm) on pure silica glass substrate were prepared from zinc acetate based precursor solutions by varying Ga doping level (0 to 6%). The presence of nanocrystalline hexagonal ZnO was confirmed by X-ray diffraction study whereas the field emission scanning and transmission electron microscopic analyses evidenced the existence of quasi-spherical ZnO with a decreased trend in crystallite/particle size vis-à-vis an enhancement of direct band gap energy of the films on increasing the doping level. Root means square (RMS) film surface roughness was determined by atomic force microscope and found maximum RMS roughness value in 1% doped film. Photoluminescence (PL) emission spectral study revealed the formation of various intrinsic/extrinsic defects along with the presence of characteristics band edge emission of ZnO at ~ 385 nm (UVPL). However, a lowest relative intensity of the UVPL emission was found in 1% doped film (G1ZO), indicating an appreciable decrease in the recombination rate of photogenerated charge carriers in the semiconductor. The photocatalytic activity of the films towards degradation of rhodamine 6G dye was performed under UV (254 nm) and obtained the maximum value of dye degradation rate constant (considering first order reaction kinetics) in 1% doped film (G1ZO). On increasing doping level, the trend in change of defect concentration (oxygen vacancies) as analyzed by Raman spectral study was found identical with the dye photodegradation activity of the films. The G1ZO film would expect to decompose micro-organisms even under exposure of visible light

Indium Oxide Based Nanomaterials: Fabrication Strategies, Properties, Applications, Challenges and Future Prospect

Nanostructured metal oxide semiconductors (MOS) in the form of thin film or bulk attract significant interest of materials researchers in both basic and applied sciences. Among these important MOSs, indium oxide (IO) is a valuable one due to its novel properties and wide range of applications in diversified fields. IO based nanostructured thin films possess excellent visible transparency, metal-like electrical conductivity and infrared reflectance properties. This chapter mainly highlights the synthesis strategies of IO based bulk nanomaterials with variable morphologies starting from spherical nanoparticles to nano-rods, nano-wires, nano-needles, nanopencils, nanopushpins etc. In addition, thin film deposition and periodic 1-dimensional (1D)/2-dimensional (2D) surface texturing techniques of IO based nanostructured thin films vis-à-vis their functional properties and applications have been discussed. The chapter covers a state-of-the-art survey on the fabrication strategies and recent advancement in the properties of IO based nanomaterials with their different areas of applications. Finally, the challenges and future prospect of IO based nanomaterials have been discussed briefly

Media optimization for biosurfactant production by Rhodococcus erythropolis MTCC 2794: artificial intelligence versus a statistical approach

This paper entails a comprehensive study on production of a biosurfactant from Rhodococcus erythropolis MTCC 2794. Two optimization techniques-(1) artificial neural network (ANN) coupled with genetic algorithm (GA) and (2) response surface methodology (RSM)-were used for media optimization in order to enhance the biosurfactant yield by Rhodococcus erythropolis MTCC 2794. ANN and RSM models were developed, incorporating the quantity of four medium components (sucrose, yeast extract, meat peptone, and toluene) as independent input variables and biosurfactant yield [calculated in terms of percent emulsification index (% EI24)] as output variable. ANN-GA and RSM were compared for their predictive and generalization ability using a separate data set of 16 experiments, for which the average quadratic errors were ~3 and ~6%, respectively. ANN-GA was found to be more accurate and consistent in predicting optimized conditions and maximum yield than RSM. For the ANN-GA model, the values of correlation coefficient and average quadratic error were ~0.99 and ~3%, respectively. It was also shown that ANN-based models could be used accurately for sensitivity analysis. ANN-GA-optimized media gave about a 3.5-fold enhancement in biosurfactant yield

Effect of precursor sol pH on microstructural, optical and photocatalytic properties of vacuum annealed zinc tin oxide thin films on glass

Dip coated vacuum annealed zinc tin oxide thin films on soda lime silica glass have been deposited from the precursor sols containing zinc acetate dihydrate and tin (IV) chloride pentahydrate (Zn:Sn = 67:33, atomic ratio in percentage) in 2-methoxy ethanol by varying sol pH (0.85-5.5). Crystallinity, morphology, optical and photocatalytic properties of the films strongly depend on sol pH. Measurement of grazing incidence X-ray diffraction confirms the presence of hexagonal nano ZnO in the films derived from the sols of pH < 5.5. Film crystallinity deteriorates on increasing sol pH and the film deposited from the sol of pH 5.5 shows XRD amorphous but the selected area diffraction pattern and HRTEM image evidence the presence of nano Zn2SnO4 (size, 5-6 nm). Direct band gap energy of films increases on increasing sol pH. To visualize the film surface microstructure, FESEM study has been done and a rod-like surface feature is revealed in the film deposited from the sol of pH 2.85. A dependence of precursor sol pH on the photocatalytic activity of films towards degradation of Rhodamine 6G dye under UV (254 nm) irradiation is found and the highest decomposition rate constant, `k' value is obtained from the film prepared from the sol of pH 5.5. The presence of zinc deficient nano Zn2SnO4 in the film may consider for generating the highest `k' value. We also measure gelling time, viscosity of sols as well as UV and FTIR studies on the films and propose chemical reactions

Immunisation status of children aged 12 to 23 months: A cross-sectional study at the immunisation clinic of a Government Medical College in West Bengal

Background: Immunisation from the very beginning of life not only reduces morbidity and mortality from potentially infectious diseases, it also interrupts disease transmission in the community. Methods: A cross-sectional study was done among children aged 12–23 months, who attended the immunisation clinic of a Medical College Hospital from 6th January to 10th February 2020. They were selected by purposive sampling. A pre-designed, pre-tested, structured questionnaire was applied to collect the relevant data from this group of children. Results: Among the 154 children who participated in the study, 43.5% of them belong to the age group of 16–19 months. 70.8% were found to be fully immunised. However, 28.6% were partially immunised children and only a single participant was found as non-immunised. The immunisation status of the study participants is significantly associated with their religion (P = 0.007) and the educational status of both the parents (P = 0.039, P = 0.04). Conclusions: Overall full immunisation coverage is satisfactory in comparison to National Family Health Survey 4 data (criterion) but not up to the national target. Increased frequency of campaigning and also catch-up immunisation programme should be taken to improve immunisation of those children who were partially immunised or not immunised at all

Modelling forward osmosis-nanofiltration integrated process for treatment and recirculation of leather industry wastewater

Modelling of a forward osmosis-nanofiltration (FOsingle bondNF) integrated treatment system for treating hazardous wastewater has been done with model validation against experimental data of a semi-pilot unit using live wastewater from a leather industry. The flat sheet cross flow forward osmosis (FO) membrane module ensured near 100% rejection of chromium while total pollution load of the wastewater in terms of chemical oxygen demand (COD), chlorides and sulphates came down by 98%. A reasonably high water flux of about 48 L/m2 h (LMH) could be sustained in the FO module. The coupled downstream NF system recovered the draw solute NaCl by more than 98% for recycling in the FO loop. That the developed model is capable of predicting system performance quite accurately is reflected in low relative error ( 0.98) and high Wilmot d-index (>0.95). The model will help assess operating conditions, system design and hence industrial scale up

Pelargonidin-PLGA nanoparticles: Fabrication, characterization, and their effect on streptozotocin induced diabetic rats

819-830Diabetes is one of the serious noncommunicable diseases affecting mankind. In India, it ranks 4th with a proportional mortality rate of 2%. Pelargonidin, a simplest anthocyanidin, is known to have potential benefit in alleviating experimental diabetes. However, insolubility in water, low stability and rapid biodegradation of pelargonidin and other flavonoids are major constrains of their effective uses. Nanocapsulation is a method of choice to overcome these limitations. We have synthesized pelargonidin-encapsulated nanoparticles by emulsion-diffusion-evaporation method using poly (D, L-lactide-co-glycolide) (PLGA), a bio-compatible polymer. The nanoparticles (P-PLGA) have been characterized by different biophysical techniques. The effects of both free pelargonidin and P-PLGA nanoparticles have been tested in streptozotocin-induced diabetic rat model. Diabetic rats were treated with 0.6 mg pelargonidin/kg body wt. or pelargonidin (P)-PLGA nanoparticles containing 0.6 mg pelargonidin/kg body wt. by intravenous injection at an interval of 3 days. Administration of two doses of P-PLGA nanoparticles proved efficient in controlling hyperglycemia and hyperlipidemia. Reduced activities of enzymatic antioxidants and elevated oxidative stress markers in diabetic rats were reverted to almost normal levels by P-PLGA nanoparticle treatment. Compared to free pelargonidin, P-PLGA nanoparticles appear to be more effective in controlling the diabetogenic effects of STZ, which may be due to improved dissolution, slow release and long-acting effect of the flavonoid in nanoparticles