Ethephon‐induced fractional changes of pectic polysaccharides in developing cape gooseberry (Physalis peruviana L) fruits

Pectic polysaccharides extracted from fruit tissue of cape gooseberry (Physalis peruviana L) at different maturity levels were fractionated and analyzed for galacturonic acid backbone molecules. Preharvest spray of the fruits at 7 days old with ethephon resulted in a higher accumulation of water‐soluble and oxalate‐soluble pectic fractions than non‐treated fruits, while this treatment effectively enhanced the polygalacturonase enzyme activity necessary for maintenance of pectin degradation. Treatment with ethephon not only enhanced the solubilization rate but also resulted in a net increase in total pectic polymer content in developing cape gooseberry fruits. Copyright © 2005 Society of Chemical Industry     

Room temperature ammonia sensor based on jaw like bis-porphyrin molecules

A jaw-like bis-porphyrin (bis-TPP) molecule was synthesized anchoring of two porphyrin molecules to a benzene ring at the meta positions through the ester linkage. The bis-TPP molecule and its zinc-derivative (Zn-bis-TPP) were spin-coated on glass surfaces to construct two chemiresistive room temperature NH₃ gas sensors. Both the films showed high selectivity, reproducibility and reversibility in sensing NH₃ gas (5–40 ppm) in air. The sensing characteristics of the Zn-bis-TPP films (response (2 s) and recovery (2.5 min) times; linear response (952%)) were better than that of the bis-TPP films (response (8 s) and recovery (7.5 min) times; linear response (131%)). This is attributed to the amorphous nature of the former.     

Effect of blend proportion on moisture management characteristics of bamboo/cotton knitted fabrics

This study reports an investigation of the effect of the blend-ratio of bamboo and cotton fibres on the moisture management properties of single jersey knitted fabrics composed of them. The moisture management properties of the fabrics were measured in SDL-ATLAS moisture management tester. The liquid transport properties of textiles, such as wetting time, maximum moisture absorption rate, maximum wetted radii, spreading speeds, cumulative one-way transport capacity and overall moisture management capacity (OMMC), have been considered and correlated to the blend ratio of bamboo/cotton yarn single jersey knitted fabrics. It was observed that as the bamboo content increased, the wetting time decreased, maximum wetted radius decreased, rate of absorption increased, spreading speed decreased and OMMC decreased.     

Influence of blend ratio and linear density on liquid spreading characteristics of bamboo/cotton-blended yarn knitted fabrics measured by liquid spread tester

In this study, a new liquid spread tester, designed and developed in an earlier work by the authors, has been used for the study and analysis of the transverse wicking characteristics of single jersey-knitted fabric produced from bamboo/cotton-blended yarn. The most significant liquid spreading characteristic, namely the liquid spreading rate, has been measured and analysed for two sets of the knitted fabric composed of bamboo/cotton yarn, one of linear density Ne 20s and the other of Ne 40s yarn. The yarn blend composition was varied in a similar manner for both sets of fabric. It was observed that liquid spreading rate decreased with increase in bamboo content for all the blend proportions investigated. It was also found that this property is higher in the wale-way direction than the course-way direction.     

Investigation on the electrical characteristics of sol-gel derived Pb1.05(Zr0.53Ti0.47)O3 thin films

Abstract

Lead zirconate titanate (PZT) thin films with composition Zr/Ti ～ 0.53/0.47 were deposited by the sol-gel technique. The films were characterized in terms of its polarization relaxation, fatigue and imprint characteristics. We have found that the polarization relaxation is due to the presence of a depolarization field which increases dramatically with the rise in temperature. Improved fatigue performance was observed when the film was fatigued with higher frequency. The direction of imprint depends on the state of polarization. With the increase in net polarization, the trapped charge density at the film-electrode interface increases which leads to imprint characteristics. Also the imprint increases considerably with the rise in temperature. Finally, we have made an attempt to correlate simultaneously fatigue, polarization relaxation, and imprint characteristics with the presence of mobile charge defects (viz. V_o) and defect dipoles (viz. V_Pb – V_o) in the film.     

An integral approach for simulation of vapour film dynamics around a spherical surface

The dynamics of a thermally driven vapour film around a solid sphere has been investigated here with both the sphere and the annular film surrounded by a large water pool. Integral models based on constant and variable vapour-phase densities have been developed here for studying a spherico-symmetric phase change problem for two immiscible phases, vapour and liquid around a hot sphere. Governing equations for both liquid and vapour phases are converted into a set of non-linear ODEs. Effects of distinct density on interface condition and density variation of vapour phase are taken into account both in energy equation of vapour phase and also in interfacial mass and energy balance. The present models have been validated with available analytical, incompressible Volume of Fluid (VOF) and experimental results of growth and collapse of either bubble or vapour film. A simple model, based on scale analysis, was evolved that successfully captured the non-monotonic growth of the film, as observed by the more detailed models under certain degree of liquid subcooling. In addition, the case of very small thermal boundary layer in the liquid side has been successfully studied for which the VOF model required very fine grid. It has been observed that the effect of density variation in the integral model results in marginally higher film growth at higher temperature. However, the effect of radiation on the film growth was found to be quite substantial. The integral model not only incorporates the effects of vapour-phase temperature variation and radiation exchange of heat but also is computationally several-fold efficient with respect to the VOF model.     

Self-tuning flexible ac transmission system controllers for power oscillation damping: a case study in real time

Design and real-time implementation of a self-tuning flexible ac transmission system (FACTS) controller is illustrated for power oscillation damping. Although the system model is not required for self-tuning control design, it is shown to perform similar to a model-based design. For parameter estimation, the classical recursive least square (RLS) is supplemented by a random walk (RW) with a switched structure and compared to standard variable forgetting factor (VFF) approach. It is shown that the RW improves the accuracy and convergence of the estimated system parameters, which is critical to self-tuning control following large disturbances. The performance is validated in real time using a commercial real-time simulation platform. The control computation time is shown to be considerably less than the typical sampling time used for power oscillation damping applications demonstrating the feasibility of self-tuning FACTS controllers in practice.     

Hydrogeochemistry and arsenic contamination of groundwater in the Ganges Delta Plain, Bangladesh

Geochemical composition and the level of Arsenic (As) contamination of groundwater in the Ganges Delta Plain, southwestern Bangladesh were elucidated. Hydrogeochemical data of tube well samples suggested that the groundwater is mostly Ca-Mg-HCO(3) type with bicarbonate (HCO(3)(-)) as the dominant anion, though other type waters are also observed. In contrast, the elevated EC, Cl(-) and high content of Na(+) relative to Ca(2+), Mg(2+) and K(+) in six groundwater samples suggest their saline origin. Low concentrations of NO(3)(-) and SO(4)(2-), and high concentrations of dissolved organic carbon (DOC), HCO(3)(-) and PO(4)(3-) indicate the reducing conditions of subsurface aquifer where sediments are deposited with abundant organic matter. The total As concentration in the analyzed samples is very high (0.0431-1.352 mg/L) along with high Fe (2.791-17.058 mg/L) and relatively low Mn (0.134-1.972 mg/L) at different depths. Distinct relationship of As with Fe and Mn, and strong correlation with DOC suggests that the biodegradation of organic matter and reductive dissolution of Fe-oxyhydroxide is considered to be the dominant processes to release As in aquifers. Moreover, negative correlation between As and SO(4)(2-) demonstrates the As may not be directly mobilized from sulfide minerals like arsenopyrite.     

Extrusion of Rice,Bean and Corn Starches: Extrudate Structure and Molecular Changes in Amylose and Amylopectin

The objective of this study was to evaluate the effects of starch source and amylose content on the expansion ratio, density, and texture of expanded extrudates, as well as to investigate the structural and molecular changes that occur in starch granules as a function of extrusion. The starches employed were rice starches (8%, 20%, and 32% amylose), carioca bean starch (35% amylose), and Hylon V^® corn starch (55% amylose). The extrudates from rice starches containing 20% and 32% amylose exhibited the highest expansion ratio, while, extrudates from Hylon V^® corn starch containing 55% amylose exhibited the lowest expansion ratio. The hardness values of the extrudates with 55% amylose were twice those of the extrudates with 20%, 32%, and 35% amylose. An additional finding was that although the amylopectin promoted the expansion of the gelatinized starch matrix, it failed to strengthen and sustain the walls of the extrudate bubbles during expansion.     

Combined removal of BTEX in air stream by using mixture of sugar cane bagasse, compost and GAC as biofilter media

Biofiltration of air stream containing mixture of benzene, toluene, ethyl benzene and o-xylene (BTEX) has been studied in a lab-scale biofilter packed with a mixture of compost, sugar cane bagasse and granulated activated carbon (GAC) in the ratio 55:30:15 by weight. Microbial acclimation was achieved in 30 days by exposing the system to average BTEX inlet concentration of 0.4194 gm(-3) at an empty bed residence time (EBRT) of 2.3 min. Biofilter achieved maximum removal efficiency more than 99% of all four compounds for throughout its operation at an EBRT of 2.3 min for an inlet concentration of 0.681 gm(-3), which is quite significance than the values reported in the literature. The results indicate that when the influent BTEX loadings were less than 68 gm(-3)h(-1) in the biofilter, nearly 100% removal could be achieved. A maximum elimination capacity (EC) of 83.65 gm(-3)h(-1) of the biofilter was obtained at inlet BTEX load of 126.5 gm(-3)h(-1) in phase IV. Elimination capacities of BTEX increased with the increase in influent VOC loading, but an opposite trend was observed for the removal efficiency. The production of CO(2) in each phase (gm(-3)h(-1)) was also observed at steady state (i.e. at maximum removal efficiency). Moreover, the high concentrations of nitrogen in the nutrient solution may adversely affect the microbial activity possibly due to the presence of high salt concentrations. Furthermore, an attempt was also made to isolate the most profusely grown BTEX-degrading strain. A Gram-positive strain had a high BTEX-degrading activity and was identified as Bacillus sphaericus by taxonomical analysis, biochemical tests and 16S rDNA gene analysis methods.