Electrochemical deposition of polyaniline–polypyrrole composite coatings on aluminum

The electrodeposition of polyaniline–polypyrrole composite coatings on aluminum was successfully performed by using cyclic voltammetry. Oxalic acid was used as the electrolyte. Electrodeposition was carried out at a scan rate of 20 mV/s by varying the number of cycles. An anodic peak current at around ?0.1 V versus saturated calomel electrode (SCE) was observed in the cyclic voltammograms. This peak is due to the oxidation and adsorption of hydrogen. The cyclic voltammograms also show another anodic peak current at around 1.0 V versus SCE, which is the characteristic peak of the polyaniline–polypyrrole composite. The behavior of this peak with respect to the number of cycles is discussed in detail. A corresponding cathodic peak current at around ?0.7 V versus SCE was also observed in the cyclic voltammograms. The infrared spectra of the composite coatings revealed the infrared peaks of both polypyrrole and polyaniline. The scanning electron micrographs of the coatings indicate a morphology completely different from its homopolymers. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1970–1977, 2002     

Two-Step Surface Modification of Chemically Resistant Polymers: Blend Formation and Subsequent Chemistry1

Supercritical fluid (SCF) carbon dioxide processing has been studied as a new route to polymer surface modification. Three fluoropolymer substrates were studied: poly(tetrafluoroethylene) (PTFE), poly(chlorotrifluoroethylene) (PCTFE) and poly(tetrafluoroethylene-co-hexafluoropropylene) (FEP) using a two-step modification procedure. In the first step, blends or semiinterpenetrating networks were prepared by carrying out a free radical polymerization of styrene (or styrene with divinylbenzene or triallyl cyanurate) within the SCF-swollen polymer substrate. The second step involved sulfonating the polystyrene using heterogeneous (solution-solid) sulfonation conditions. Composition of the surfaces was determined by X-ray photoelectron spectroscopy, and wettability was assessed using water contact angle measurements. Depressed advancing and receding contact angles indicate increased wettability of all of the fluoropolymer samples.     

Improving the evaluation sensitivity of an ultrasonic pulse echo technique using a neural network classifier

In this paper, the use of an artificial neural network (ANN) for classifying weak ultrasonic signals has been attempted. The limitations of using a single conventional parameter for signal detection and classification (namely peak amplitude alone) are highlighted. Use of a multi-parameter approach is suggested. The ANN used is a multi-layered, feedforward, error- backpropagation network. Results are compared with those of conventional approaches.     

Radioprotection by quercetin-3-O-rutinoside,a flavonoid glycoside – A cellular and mechanistic approach

The present study was aimed to evaluate the in vivo radioprotective efficacy of quercetin-3-O-rutinoside (PMC-1), the key bioactive constituent flavonoid glycoside isolated from the whole plant of Pilea microphylla was evaluated. In vivo survival studies established the optimum effective dose of PMC-1 at 25 mg/kg/i.p. At the optimum dose, PMC-1 prevented the depletion of endogenous antioxidants in the liver of irradiated mice. In vivo protection towards gastrointestinal tract and haematopoietic system was confirmed by the restoration of radiation-induced reduction in villi height, number of crypt cells and spleen index. PMC-1 also attenuated the radiation-induced apoptosis in spleenocytes significantly. Single cell gel electrophoresis of peripheral blood leukocytes showed inhibition of radiation-induced DNA damage by PMC-1. PMC-1 pretreatment significantly reversed the changes by increasing pro-survival (ERK) and decreasing pro-apoptotic (BAX) gene expressions compared to radiation control. Thus, PMC-1 exhibits protective effects against γ-radiation and the probable mechanism of action involves maintenance of antioxidant enzymes, prophylactic action and inhibition of apoptosis.     

Building energy efficiency labeling programme in Singapore

The use of electricity in buildings constitutes around 16% of Singapore's energy demand. In view of the fact that Singapore is an urban city with no rural base, which depends heavily on air-conditioning to cool its buildings all year round, the survival as a nation depends on its ability to excel economically. To incorporate energy efficiency measures is one of the key missions to ensure that the economy is sustainable. The recently launched building energy efficiency labelling programme is such an initiative. Buildings whose energy performance are among the nation's top 25% and maintain a healthy and productive indoor environment as well as uphold a minimum performance for different systems can qualify to attain the Energy Smart Office Label. Detailed methodologies of the labelling process as well as the performance standards are elaborated. The main strengths of this system namely a rigorous benchmarking database and an independent audit conducted by a private accredited Energy Service Company (ESCO) are highlighted. A few buildings were awarded the Energy Smart Office Label during the launching of the programme conducted in December 2005. The labeling of other types of buildings like hotels, schools, hospitals, etc. is ongoing.     

Anomalous Oxidation States in Multilayers for Fuel Cell Applications

Significant recent interest has been directed towards the relationship between interfaces and reports of enhanced ionic conductivity. To gain a greater understanding of the effects of hetero‐interfaces on ionic conductivity, advanced analytical techniques including electron microscopy (TEM/STEM), electron energy loss spectroscopy (EELS), and secondary ion mass spectrometry (SIMS) are used to characterize CeO₂/Ce_0.85Sm_0.15O₂ multilayer thin films grown by pulsed laser deposition. High quality growth is observed, but ionic conductivity measured by impedance spectroscopy and ¹⁸O tracer experiments is consistent with bulk materials. EELS analysis reveals the unusual situation of layers containing only Ce(IV) adjacent to layers containing both Ce(III) and Ce(IV). Post oxygen annealing induced oxygen diffusion and mixed oxidation states in both layers, but only in the vicinity of low angle grain boundaries perpendicular to the layers. The implications of the anomalous behavior of the Ce oxidation states on the design of novel electrolytes for solid oxide fuel cells is discussed.     

Recipe determination and scheduling of gasoline blending operations

Gasoline is a major contributor to the profit of a refinery. Scheduling gasoline‐blending operations is a critical and complex routine task involving tank allocation, component mixing, blending, product storage, and order delivery. Optimized schedules can maximize profit by avoiding ship demurrage, improving order delivery, minimizing quality give‐aways, avoiding costly transitions and slop generation, and reducing inventory costs. However, the blending recipe and scheduling decisions make this problem a nonconvex mixed‐integer nonlinear program (MINLP). In this article, we develop a slot‐based MILP formulation for an integrated treatment of recipe, specifications, blending, and storage and incorporate many real‐life features such as multipurpose product tanks, parallel nonidentical blenders, minimum run lengths, changeovers, piecewise constant profiles for blend component qualities and feed rates, etc. To ensure constant blending rates during a run, we develop a novel and efficient procedure that solves successive MILPs instead of a nonconvex MINLP. We use 14 examples with varying sizes and features to illustrate the superiority and effectiveness of our formulation and solution approach. The results show that our solution approach is superior to commercial solvers (BARON and DICOPT). © 2009 American Institute of Chemical Engineers AIChE J, 2010     

Growth and Studies of Calcium Doped Laser Ablated Barium Titanate Thin Films

Ba_{1 ? x}Ca_xTiO₃ targets were prepared by conventional solid state reaction with varied amounts of the calcium content (5 at.%, 10 at.%) and the thin films were deposited on Pt(111) coated Si substrate using pulsed laser ablation technique. The thin films were deposited at different pressures and temperatures, so as to determine the optimized growth parameter for the good quality BCT thin films. The pressure variation on the growth parameters made a dramatic impact in tailoring the dielectric constant and phase transition. The phase evolution of the BCT thin films evolves from 450°C and at higher substrate temperatures (～700°C) for different partial pressures of oxygen, the preferred orientation of the thin films were observed. The SIMS analysis reveals a sharp interface exist at the bottom electrode (Pt)–BCT thin films indicating no interdiffusion taking place which might lead to the degradation of devices. The BCT thin films deposited at higher pressures (>60 mtorr) exhibited higher Ba content indicating the possibility of the Ca occupying the Ti site and is reflected in the decrease of the dielectric phase transition temperature. The ferroelectric hysteresis and Capacitance voltage measurement shows the signature of ferroelectricity.