Cerium vanadate/carbon nanotube hybrid composite nanostructures as a high-performance anode material for lithium-ion batteries

The pristine CeVO4 and CeVO4/CNT hybrid composite nanostructured samples were facilely synthesized using a simple silicone oil-bath method.From the X-ray diffra...     

Dispersion of Colloidal Alumina using a Rhamnolipid Biosurfactant

Dispersability of colloidal alumina in water has been studied using a rhamnolipid containing biosurfactant. Zeta potential measurements revealed that the surface charge of alumina was altered due to adsorption of the biosurfactant and the iso‐electric‐point of alumina shifted from pH 9 to 6.3. Sedimentation tests indicated that the alumina suspension was completely dispersed for 3–5 hours in the presence of biosurfactant after which some settling was observed. Stability of the suspension in the time period studied was found to be independent of pH. Capillary suction time measurements showed that the alumina suspension was dispersed in the presence of the biosurfactant and varied with pH. Maximum dispersion is obtained in the pH range of 3.5–5 and 7–11 while a minimum is obtained around pH 6. This behavior is consistent with the changes in zeta potential in the presence of the biosurfactant and thus capillary suction time measurements appeared to be more reliable than the sedimentation tests. Optimization studies showed that about 60 mg/g of biosurfactant was necessary for best dispersion and dispersion could be done up to 40% solids. The application of a natural biosurfactant for dispersing colloidal alumina has been demonstrated.     

Determination of organophosphate pesticides at a carbon nanotube/organophosphorus hydrolase electrochemical biosensor

An amperometric biosensor for oganophosphorus (OP) pesticides based on a carbon nanotube (CNT)-modified transducer and an organophosphorus hydrolase (OPH) biocatalyst is described. A bilayer approach with the OPH layer atop of the CNT film was used for preparing the CNT/OPH biosensor. The CNT layer leads to a greatly improved anodic detection of the enzymatically generated p-nitrophenol product, including higher sensitivity and stability. The sensor performance was optimized with respect to the surface modification and operating conditions. Under the optimal conditions the biosensor was used to measure as low as 0.15 μM paraoxon and 0.8 μM methyl parathion with sensitivities of 25 and 6 nA/μM, respectively.     

Degradation process in organic thin film devices fabricated using P3HT

The stability of regioregular poly(3-hexylthiophene 2,5-diyl) (P3HT) thin films sandwiched between indium tin oxide (ITO) and aluminium (Al) electrodes have been investigated under normal environmental conditions (25°C and RH∼45–50%). Electrical and optical properties of ITO/P3HT/Al devices have been studied over a period of 30 days. Mobility μ of the order of 10⁻⁴ cm²/V-s has been obtained from the V ² law in the as-deposited P3HT films. Scanning electron microscopy (SEM) investigations show blistering of Al contacts in devices with a poly(3,4-ethylenedioxythiophene) (PEDOT) interlayer on application of voltage whereas no blistering is seen in devices without PEDOT. The results have been explained in terms of trap generation and propagation and the moisture-absorbing nature of PEDOT.      

Solid-state fermentation for production of phytase by Rhizopus oligosporus

Solid-state fermentation of coconut oil cake has been carried out with Rhizopus oligosporus for the production of phytase. Phytase is used commercially in the animal feed industry to improve animal performance because there is a substantial and growing interest among swine and poultry producers in the application of phytase to improve the nutritional quality in animal feeds. Demonstrated benefits include improved feed yield ratios and reduction in the environmental costs associated with the disposal of animal wastes. We report the production of extracellular phytase by R. oligosporus under solid-state fermentation using coconut oil cake as substrate. Maximal enzyme production (14.29 U/g of dry substrate) occurred at pH 5.3, 30°C, and 54.5% moisture content after 96 h of incubation. The addition of extra nutrients to the substrate resulted in inhibition of product formation. The results indicate the scope for production of phytase using coconut oil cake as solid substrate without additional nutrients.     

Relationship between coffee husk caffeine degradation and respiration of Aspergillus sp. LPBx in solid-state fermentation

Studies were carried out in a packed-bed column fermentor using coffee husk as substrate in order to verify a relationship between caffeine degradation and the respiration of Aspergillus sp. LPBx. Fermentation conditions were optimized by using factorial design experiments. The kinetic study showed that the caffeine degradation was related to the development of mold and its respiration and also with the consumption of reducing sugars present in coffee husk. From the values obtained experimentally for oxygen uptake rate and CO₂ evolved, we determined a biomass yield of 3.811 g of biomass/g of consumed O₂ and a maintenance coefficient of 0.0031 g of consumed O₂/(g of biomass·h). The maximum caffeine degradation achieved was 90%.     

Local disruption of DNA-base stacking by bulky base surrogates

A novel biphenyl base surrogate disrupts 2-aminopurine base stacking while maintaining duplex integrity.