Chemically modified fly ash for fabricating super-strong biodegradable poly(vinyl alcohol) composite films

Composite films of poly(vinyl alcohol) (PVA) and chemically modified fly ash (MFA) by sodium hydroxide were prepared by aqueous cast method with 5, 10, 15, 20 and 25 wt% MFA treated with 1 wt% cross-linking agent (glutaraldehyde, GLA). The tensile strengths of the composite films were found to increase proportionally with MFA and the maximum strength attained was 414% higher in the case of 20 wt% MFA than that in neat PVA film. The percentage of strain at break exponentially decreased with addition of MFA. The modulus of the composites was determined to increase proportionally up to a maximum 685% at 20 wt% MFA compared to that of neat PVA film. Interfacial networking between the MFA and PVA was evident from scanning electron microscopy (SEM) images of tensile-fractured surfaces, which was not observed for the unmodified fly ash (FA) system. Atomic force microscopy (AFM) analysis showed that the mean square surface roughness of the composite films of PVA–MFA was 53% smoother than the films with FA.     

Development of biodegradable conductive cotton yarns by in-situ polymerisation of pyrrole

Cotton yarns were modified with pyrrole in the presence of ferric chloride following a dip-nip-dry technique. Treatment of cotton with 23.4% aqueous pyrrole followed by treatment with 40.6% aqueous ferric chloride and subsequent drying in atmospheric air produced balanced improvements in the properties of the yarn such as conductivity, tensile strength and extensibility. Among the three types of yarns such as ring spun, rotor spun and friction spun considered for such treatment, ring spun yarn performed best in respect of conductivity and retention of strength. Examination of surface morphology of yarns by scanning electron microscopy revealed a common discontinuity in the growth of polypyrrole along the length of the yarns spun using friction spinning and rotor spinning systems. Such discontinuity was caused by the wrapper fibres. Ring spun yarn, on the other hand, allowed a continuous spiral growth and deposition of polypyrrole in the inter-fibre space and on the surface of the yarn. Study of pyrrole modified ring spun yarn in a typical photoluminescence system indicated photoluminescence property of such pyrrole-treated cotton yarn.     

Optimization studies of a multikilowatt PIE CO2laser

Details of an investigation of the operational performance of a 10 kW CW PIE CO2laser are presented. The results obtained from the experiment, successfully scaled by an order of magnitude from an earlier proof-of-principle device, clearly document that the PIE excitation process can be effectively utilized in the design of very large volume lasers. Optimization data further reveal that overall wallplug efficiency is commensurate with that obtained fromE-beam sustained lasers; but at far less complexity and cost. As such, this relatively simple and reliable nonself-sustained excitation process appears attractive for the commercial development of very large and cost effective CW CO2lasers.     

Spin-up and spin-down of a viscous fluid over a heated disk rotating in a vertical plane in the presence of a magnetic field and a buoyancy force

Summary The hydromagnetic spin-up and spin-down of an incompressible electrically conducting fluid on a heated infinite disk rotating in a vertical plane in the presence of a magnetic field and a buoyancy force have been studied. The flow is non-axisymmetric due to the imposition of the buoyancy force. We have considered the situation where there is an initial steady state which is perturbed by suddenly changing the angular velocity of the disk. By using suitable transformations the Navier-Stokes and energy equations with four independent variables (x, y, z, t) are reduced to a system of partial differential equations with two independent variables (,t ^*). Also, these transformations uncouple the momentum and energy equations, resulting in a primary axisymmetric flow with an axial magnetic field, in an energy equation dependent on the primary flow and in a buoyancy induced secondary cross flow dependent on both primary flow and energy.The results indicate that the effect of the step-change in the angular velocity of the disk is more pronounced on the primary flow than on the secondary flow and the temperature field. For both spin-up and spin-down cases the surface shear stress in the non-axial direction normal to gravity for the primary flow and the surface shear stresses for the secondary flow increase with the magnetic parameter, whilst the surface shear stress in the vertical direction and the heat transfer at the surface decrease as the magnetic parameter increases. Also, the secondary flow near the disk dominates the primary flow. We have also developed an asymptotic analysis for large magnetic parameters which complements well the numerical results obtained in the lower magnetic parameter range.     

Electrical discharge and laser gain characteristics of a coaxialdischarge CO2 laser stabilized by a transverse rotatingmagnetic field

The feasibility of creating laser excitation in a diffusion cooled annular coaxial geometry CO₂ laser by a longitudinal DC electrical discharge stabilized with a rotating transverse magnetic field has been demonstrated. The uniformity of the electrical discharge in the annular cross section could be enhanced considerably with the application of the magnetic field. A peak laser small-signal gain of 0.3 m^-1 was obtained. This scheme could be utilized to construct a compact high-power diffusion cooled CO₂ laser system     

The relationship between gamma and delta hydrides in zirconium-hydrogen alloys of low hydrogen concentration

The stability of the γ-hydrides and the possible existence of a δ-hydride → γ-hydride transformation has been studied in sponge zirconium sheet containing up to 500 ppm hydrogen (4.33 at %) at temperatures in the range 150–250°C. Ageing of quenched specimens which initially contained only γ-hydrides resulted in the replacement of this phase by δ-hydrides at a rate which was dependent on temperature, while ageing of the furnace-cooled specimen, which initially contained only δ-hydrides did not result in a change in the type of hydrides present. Evidence was obtained which showed that the replacement of γ-hydride by δ-hydride could involve an in-situ transformation. The results support the view that γ-hydride is a metastable transition precipitate and δ-hydride is the equilibrium phase.     

Effect of protein fusion on the transition temperature of an environmentally responsive elastin-like polypeptide: a role for surface hydrophobicity?

The limited throughput, scalability and high cost of protein purification by chromatography provide motivation for the development of non-chromatographic protein purification technologies that are cheaper and easier to implement in a high-throughput format for proteomics applications and to scale up for industrial bioprocessing. We have shown that genetic fusion of a recombinant protein to an elastin-like polypeptide (ELP) imparts the environmentally sensitive solubility property of the ELP to the fusion protein, and thereby allows selective separation of the fusion protein from Escherichia coli lysate by aggregation above a critical temperature (T(t)). Further development of ELP fusion proteins as widely applicable purification tools necessitates a quantitative understanding of how fused proteins perturb the ELP T(t) such that purification conditions (T(t)) may be predicted a priori for new recombinant proteins. We report here the effect that fusing six different proteins has on the T(t) of an ELP. A negative correlation between T(t) and the fraction hydrophobic surface area on the fused proteins was observed, which was determined from computer modeling of the available three-dimensional structure. The thermally triggered aggregation behavior of ELP-coated, functionalized gold colloids as well as ligand binding to the tendamistat-ELP fusion protein support the hypothesis that hydrophobic surfaces in molecular proximity to ELPs depress the ELP T(t) by a mechanism analogous to hydrophobic residue substitution in the ELP repeat, Val-Pro-Gly-Xaa-Gly.     

Preparation of ZSM-5 Zeolite Honeycomb Monoliths Using Microporous Silica Obtained from Metakaolinite

Zeolite honeycomb monoliths were prepared from ZSM-5 powders synthesized under hydrothermal conditions using microporous silica obtained by selective leaching of metakaolinite. This honeycomb material was compared with those prepared using alkoxides (TEOS) as the silica source. The honeycomb monoliths were formed by extrusion of paste made from the synthesized powders through a multi-channel honeycomb die. The morphology and porous properties of these materials were studied using XRD, FTIR, SEM and N₂/Ar adsorption. ZSM-5 grains in the monoliths prepared from metakaolinite showed platy morphology with preferred orientation of the crystals in the extruded surface, and displayed an absence of secondary growth. The twinned morphology of ZSM-5 crystals was observed in the monoliths prepared using TEOS and this contributed to an increase in the external surface area even though the total surface area was identical to that of samples prepared from metakaolinite. The physical properties, thermal stability and mechanical strength of the monoliths was compared with zeolite-coated honeycombs. The results show that microporous silica prepared by acid leaching of metakaolinite is a cost-effective raw material for preparing ZSM-5 honeycomb monoliths with controlled morphology and tunable SiO₂/Al₂O₃ ratios.     

Water Balance Simulation and Economic Analysis for Optimal Size of On-Farm Reservoir

Rainfed rice in eastern India suffers frequent moisture stress leading to severe yield reduction due to uncertainty of rainfall coupled with inadequate field level rainwater conservation structures. Construction of the on-farm reservoir (OFR) is an alternative for the storage of excess rainwater from the diked rice field during monsoon season followed by its reuse as supplemental irrigation to the rice in the same season and pre-sowing irrigation to mustard in the winter season. For determining the optimum size of the OFR, water balance model in the cropped fields (both rice and mustard) as well as in the OFR was developed along with economic analysis. Simulation study revealed that an OFR of 12% of the farm area having 2 m depth of trapezoidal section would be optimal for rice-mustard cropping system. The above-mentioned optimum size of the OFR provides the benefit cost ratio (BCR), internal rate of return (IRR) and pay back period (PBP) as 1.23, 15.5% and 15 yr, respectively for dry year. Values of BCR, IRR and PBP for average year were simulated as 1.22, 15% and 15 yr, respectively, and those for the wet year were 1.21, 14.8% and 16 yr, respectively. To justify the investment in the OFR irrigation system, field experiments were conducted for three years. The observed BCR, IRR and PBP from the experiment were found to be 1.17, 14.8% and 16 yr, respectively.