Charge dynamics in conducting polyaniline-metal oxalate composites

Polyaniline (Pani) and its metal oxalate composites (∼10 wt.%) of trivalent metal ions of Cr, Fe, Mn, Co and Al were synthesized by chemical oxidative polymerization technique with potassium perdisulphate oxidant in aqueous sulphuric acid medium. These materials were characterized by UV-VIS and EPR spectral techniques. Their d.c. electrical conductivities at room temperature and also as a function of temperature (307-453 K) were measured by four- probe technique. Presence of radical cation/polaron transition was indicated by UV- VIS absorption peak and EPR signals. Further, a close correlation existed between the conductivities and EPR parameters such as line width and peak ratio, which demonstrated that both mobile and fixed spins are involved in these composites. The dependence of conductivity on temperature, when analysed graphically by VRH, GB and TC mechanisms, pointed out that VRH is the predominant charge transport mechanism in these materials.     

High speed classification of individual bacterial cells using a model-based light scatter system and multivariate statistics

We describe a model-based instrument design combined with a statistical classification approach for the development and realization of high speed cell classification systems based on light scatter. In our work, angular light scatter from cells of four bacterial species of interest, Bacillus subtilis, Escherichia coli, Listeria innocua, and Enterococcus faecalis, was modeled using the discrete dipole approximation. We then optimized a scattering detector array design subject to some hardware constraints, configured the instrument, and gathered experimental data from the relevant bacterial cells. Using these models and experiments, it is shown that optimization using a nominal bacteria model (i.e., using a representative size and refractive index) is insufficient for classification of most bacteria in realistic applications. Hence the computational predictions were constituted in the form of scattering-data-vector distributions that accounted for expected variability in the physical properties between individual bacteria within the four species. After the detectors were optimized using the numerical results, they were used to measure scatter from both the known control samples and unknown bacterial cells. A multivariate statistical method based on a support vector machine (SVM) was used to classify the bacteria species based on light scatter signatures. In our final instrument, we realized correct classification of B. subtilis in the presence of E. coli,L. innocua, and E. faecalis using SVM at 99.1%, 99.6%, and 98.5%, respectively, in the optimal detector array configuration. For comparison, the corresponding values for another set of angles were only 69.9%, 71.7%, and 70.2% using SVM, and more importantly, this improved performance is consistent with classification predictions.     

Geosynthetic-encased stone columns: Numerical evaluation

Stone columns (or granular piles) are increasingly being used for ground improvement, particularly for flexible structures such as road embankments, oil storage tanks, etc. When the stone columns are installed in extremely soft soils, the lateral confinement offered by the surrounding soil may not be adequate to form the stone column. Consequently, the stone columns installed in such soils will not be able to develop the required load-bearing capacity. In such soils, the required lateral confinement can be induced by encasing the stone columns with a suitable geosynthetic. The encasement, besides increasing the strength and stiffness of the stone column, prevents the lateral squeezing of stones when the column is installed even in extremely soft soils, thus enabling quicker and more economical installation. This paper investigates the qualitative and quantitative improvement in load capacity of the stone column by encasement through a comprehensive parametric study using the finite element analysis. It is found from the analyses that the encased stone columns have much higher load carrying capacities and undergo lesser compressions and lesser lateral bulging as compared to conventional stone columns. The results have shown that the lateral confining stresses developed in the stone columns are higher with encasement. The encasement at the top portion of the stone column up to twice the diameter of the column is found to be adequate in improving its load carrying capacity. As the stiffness of the encasement increases, the lateral stresses transferred to the surrounding soil are found to decrease. This phenomenon makes the load capacity of encased columns less dependent on the strength of the surrounding soil as compared to the ordinary stone columns.     

Utilization of flyash as filler for unsaturated polyester resin

Flyash is an inexpensive material that can reduce the overall cost of the composite if used as a filler for unsaturated polyester resin (PR). Flyash-filled unsaturated polyester resin (FPR) was cast into sheets. The tensile strength, flexural strength, and flexural modulus were determined. Calcium carbonate-filled polyester resin (CPR) and PR were also cast into sheets. The above-mentioned properties were determined and a comparison was made. The filler concentration was varied from 0 to 15 wt %. It was found that FPR was inferior to CPR and PR composites with respect to tensile and flexural strengths. But FPR was found to have a higher flexural modulus than those of CPR and PR. FPR with 10% flyash was found to have poor acid and solvent (benzene) resistances and good saltwater, alkali, weathering, and freeze–thaw resistances as seen from the mechanical properties. The possible ways of improving the strength of FPR are discussed. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 1385–1391, 1998     

An analytic network process-based multicriteria decision making model for a reverse supply chain

Reverse logistics has emerged as an important dimension for organizations to build their strategic advantage. Part of this effort relies on potentially outsourcing these activities. With this competitive issue in mind, this paper presents a multistep process to select a third-party reverse logistic provider (3PRLP). Criteria for evaluation are drawn from the literature and practical input from experts and decision makers within a case company. The process requires that an initial screening of criteria is completed through the analytical hierarchy process. The second stage of the process, 3PRLP selection, is completed using the analytic network process. An illustrative example is provided to demonstrate the solutions obtained by the proposed process within an automobile case company. A sensitivity analysis is also provided for a robustness check. The results obtained from the proposed model provide some interesting managerial implications to the case company and others wishing to apply the process.     

Heat transfer and pressure drop characteristics in a circular tube fitted with and without V-cut twisted tape insert

The effect of V-cut twisted tape insert on heat transfer, friction factor and thermal performance factor characteristics in a circular tube were investigated for three twist ratios (y = 2.0, 4.4 and 6.0) and three different combinations of depth and width ratios (DR = 0.34 and WR = 0.43, DR = 0.34 and WR = 0.34, DR = 0.43 and WR = 0.34). The obtained results show that the mean Nusselt number and the mean friction factor in the tube with V-cut twisted tape (VTT) increase with decreasing twist ratios (y), width ratios (WR) and increasing depth ratios (DR). Subsequently an empirical correlation also was formulated to match with experimental results with ± 6% variation for the Nusselt number and ± 10% for the friction factor.     

Prominent catalytic activity of mesoporous molecular sieves in the vapor phase dehydration of cyclohexanol to cyclohexene

Cerium incorporated KIT-6 mesoporous materials were synthesized through direct hydrothermal method and characterized by using X-ray diffraction (XRD), nitrogen sorption isotherm (BET), Fourier transform infrared spectroscopy (FT-IR), inductively coupled plasma -atomic emission spectroscopy (ICP-AES), diffuse reflectance ultraviolet visible spectroscopy (DRS-UV-Vis), thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) methods. It appeared that stable cerium ions were inserted into the silica framework of KIT-6, thus generating acid properties in their host materials. The catalytic activity of Ce-KIT-6 materials was evaluated in the vapor phase dehydration of cyclohexanol to cyclohexene and dicyclohexyl ether at different temperatures with various Si/Ce molar ratios. Ce-KIT-6 (25) showed higher activity with 54% cyclohexanol conversion and 64% selectivity to cyclohexene. The catalytic results indicated that Ce-KIT-6 mesoporous materials could be used as versatile and stable acid catalysts.     

Rietveld X-ray diffraction analysis of nanostructured rutile films of titania prepared by pulsed laser deposition

Rietveld powder X-ray diffraction analysis of the rutile films of titanium oxide prepared by pulsed laser deposition was carried out. The crystallite size increased with increase of substrate temperature, while the strain showed a reverse trend. The films synthesized at temperature ≥573 K showed that the crystal structure was almost close to that of bulk rutile structure. The influence of the substrate temperature on the lattice parameters and oxygen coordinates were also studied in the present work.     

Silver acetate interactions with nicotine and non-nicotine smoke components.

Oral topical silver-containing formulations were marketed in the 1970s and 1980s as smoking deterrents, based on the finding that when using such formulations, an unpleasant taste occurs upon smoking. This approach has not been widely adopted, however, in part because of a lack of efficacy data. The advent of new pharmacologic treatments for smoking cessation renews the possibility that such a taste aversion approach may be a useful adjunct to smoking cessation treatment. This study explored the basic mechanistic question of whether topical oral silver acetate solution interacts with nicotine as opposed to non-nicotine smoke constituents. We recruited 20 smoking volunteers to rate nicotine-containing or denicotinized cigarettes, as well as the Nicotrol nicotine vapor inhaler and sham (air) puffs. In two sessions, subjects rated the sensory and hedonic qualities of puffs after rinsing their mouths with either silver acetate solution or deionized water (placebo). Silver acetate relative to placebo solution substantially reduced liking and satisfaction ratings for the usual brand and denicotinized cigarettes; in contrast, for the nicotine inhaler these ratings were unaffected by the silver-based treatment. These results support the conclusion that silver acetate not only renders the taste of cigarette smoke less appealing, but also that the compound appears to interact selectively with non-nicotine smoke constituents. Moreover, these data suggest silver acetate would be compatible with buccal nicotine delivery systems (e.g., nicotine lozenge or gum). Combined use of taste aversion with nicotine replacement therapy could provide the smoker with additional assistance to resist relapse. Further exploration is warranted of the use of silver-based preparations as a short-term adjunct to smoking cessation treatment. (PsycINFO Database Record (c) 2010 APA, all rights reserved)