Perfluoro(methylcyclohexane) plasma polymer thin film: Growth,surface morphology,and properties investigated by scanning thermal microscopy

Scanning thermal microscopy (SThM) has been used for the visualization and characterization of an ultrathin plasma polymer film of perfluoro(methylcyclohexane) at a submicrometer level. The morphology, molecular dynamics, and lateral homogeneity of the ultrathin film have all been examined precisely with SThM. The growth of the plasma polymer film on a silicon wafer (Si‐wafer) has also been precisely determined using a new burning‐hole technique. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 1392–1400, 2005     

Onset of quark-hadron duality in pion electroproduction

A large data set of charged-pion (pi+/-) electroproduction from both hydrogen and deuterium targets has been obtained spanning the low-energy residual-mass region. These data conclusively show the onset of the quark-hadron duality phenomenon, as predicted for high-energy hadron electroproduction. We construct several ratios from these data to exhibit the relation of this phenomenon to the high-energy factorization ansatz of electron-quark scattering and subsequent quark-->pion production mechanisms.     

A literature review on dynamic pricing of electricity

Revenue management and dynamic pricing are concepts that have immense possibilities for application in the energy sector. Both can be considered as demand-side management tools that can facilitate the offering of different prices at different demand levels. This paper studies literature on various topics related to the dynamic pricing of electricity and lists future research avenues in pricing policies, consumers’ willingness to pay and market segmentation in this field. Demand and price forecasting play an important role in determining prices and scheduling load in dynamic pricing environments. This allows different forms of dynamic pricing policies to different markets and customers depending on customers’ willingness to pay. Consumers’ willingness to pay for electricity services is also necessary in setting price limits depending on the demand and demand response curve. Market segmentation can enhance the effects of such pricing schemes. Appropriate scheduling of electrical load enhances the consumer response to dynamic tariffs.     

Influence of the orientation of a square cylinder on the wake properties

An experimental investigation of flow around a square cylinder placed at various angles with respect to the approach fluid velocity is reported. The focus of the study is toward examining the sensitivity of the wake properties to the cylinder orientation and Reynolds number. Angles of incidence in the range of 0-60° and Reynolds numbers of 1340, 4990, and 9980 have been considered. Velocity measurements have been carried out using an X-wire hotwire anemometer. The Strouhal number and the drag coefficient of the cylinder have been computed from the wake measurements. Utilizing the velocity traces at distinct probe locations in the near and the far wake, statistical properties such as the RMS velocities and the spectra have been obtained. Results obtained in the present work revealed that for a cylinder with zero inclination, flow separates from the corners on the face exposed to the incoming flow. For inclinations greater than zero, the points of separation on the cylinder move downstream and the wake size increases, but the separated shear layer rolls up over a shorter distance. These factors lead to a reduced drag coefficient and a higher Strouhal number. The center-line recovery of the time-averaged velocity and the decay rates of velocity fluctuations depend on the Reynolds number. A marginal effect of the cylinder orientation is also seen.     

Surfactant-induced aggregation patterns of thiazole orange: a photophysical study

The aggregation behavior of the DNA marker dye thiazole orange (TO), has been investigated in two types of surfactant assemblies, namely, premicelles/micelles of sodium dodecyl sulfate (SDS) and pre reverse micelles/reverse micelles of sodium bis(2-ethylhexyl) sulfosuccinate (AOT). In the case of an SDS/water system, absorption spectral changes of TO signify the formation of H-aggregates and H-dimers of the dye at premicellar concentrations, which subsequently convert to the monomeric form beyond the critical micellar concentration (cmc). Interestingly, the observed changes in the absorption and emission characteristics due to the surfactant-induced formation of H-aggregates/dimers of TO are found to be useful to estimate the surfactant concentration parameters for premicellar aggregation of SDS. In the case of an AOT/n-heptane system, similarly, H-aggregates/dimers are observed at low AOT concentrations, below the cmc. However, in this case, the H-dimers persist even beyond the cmc. This is attributed to the strong tendency of TO for self-aggregation and its favorable electrostatic interactions with the AOT head groups. With increasing water content in the AOT reverse micelles, the hydration of the dye leads to the conversion of H-dimers to the monomeric form. The steady-state fluorescence results are nicely corroborated with those from time-resolved fluorescence studies and demonstrate the interesting behavior of the surfactant-induced aggregation of TO dye.     

Free volume related fluorescent behavior in electron beam irradiated chalcone doped PVA

Effect of electron irradiation on the free volume related microstructural and optical properties of chalcone doped Poly(vinyl alcohol) composite films have been studied using FTIR, UV-Visible, XRD and Positron Annihilation techniques. The FTIR spectral study shows that the irradiation induces the crosslinking within the composite. Using UV-Visible absorption spectra the optical energy band gap and activation energies were estimated and the variation of these parameters suggests the existence of defects and molecular ordering within the irradiated composite. XRD diffractograms reveal that the crosslinking enhances the crystallinity of the sample. In this cross-linked polymer composite the fluorescence enhancement has been observed in the fluorescence spectral study. The Positron annihilation result suggests that the irradiation affects the free volume properties and crosslinking hinders the chalcone chromophore molecular rotation. Under this restricted condition the chromophore molecules likely to emit enhanced fluorescence and its mobility is directly related to the free volume around it.     

DNA-directed artificial light-harvesting antenna

Designing and constructing multichromophoric, artificial light-harvesting antennas with controlled interchromophore distances, orientations, and defined donor-acceptor ratios to facilitate efficient unidirectional energy transfer is extremely challenging. Here, we demonstrate the assembly of a series of structurally well-defined artificial light-harvesting triads based on the principles of structural DNA nanotechnology. DNA nanotechnology offers addressable scaffolds for the organization of various functional molecules with nanometer scale spatial resolution. The triads are organized by a self-assembled seven-helix DNA bundle (7HB) into cyclic arrays of three distinct chromophores, reminiscent of natural photosynthetic systems. The scaffold accommodates a primary donor array (Py), secondary donor array (Cy3) and an acceptor (AF) with defined interchromophore distances. Steady-state fluorescence analyses of the triads revealed an efficient, stepwise funneling of the excitation energy from the primary donor array to the acceptor core through the intermediate donor. The efficiency of excitation energy transfer and the light-harvesting ability (antenna effect) of the triads was greatly affected by the relative ratio of the primary to the intermediate donors, as well as on the interchromophore distance. Time-resolved fluorescence analyses by time-correlated single-photon counting (TCSPC) and streak camera techniques further confirmed the cascading energy transfer processes on the picosecond time scale. Our results clearly show that DNA nanoscaffolds are promising templates for the design of artificial photonic antennas with structural characteristics that are ideal for the efficient harvesting and transport of energy.     

Chromatographic separation of carrier free 90Y from 90Sr using a diglycolamide based resin for possible pharmaceutical applications

N,N,N',N'-tetraoctyl diglycolamide (TODGA) has been used as the stationary phase in an extraction chromatography resin (XCR) material prepared for evaluating the uptake and the separation behaviour of (90)Y and (90)Sr from acidic feeds. Chromosorb-W was used as the solid support material while the feed solution was usually 4M HNO(3). The batch uptake studies have suggested almost no Sr(II) uptake while Y(III) uptake increased with acidity up to 4M HNO(3) beyond which a decrease in the K(d,w) values were observed. Column studies were carried out and breakthrough profiles were obtained for both Y(III) and Sr(II). No breakthrough of Y(III) was noticed even when >50 column volumes of the feed (carrier free (90)Y at 4 M HNO(3)) was passed through the column while about 20 column volumes were required for the breakthrough of Y(III) when the feed contained 1 g/L Y in 4 M HNO(3) spiked with (90)Y tracer. The reusability of the column was also studied which indicated in the deterioration of the column performance as shown by the sharp fall in the breakthrough volumes and was attributed to the probable leaching of the reagent from the support material. The role of absorbed dose was also investigated for Y(III) uptake. Separation of carrier free (90)Y tracer was carried out by loading the column with (90)Sr and eluting with 0.01M solutions of HNO(3) as well as EDTA. The purity of the product was ascertained by half-life method.     

An optimization-based decision support system for strategic planning in a process industry: the case of aluminium company in India

We describe how a generic multi-period optimization-based decision support system (DSS) can be used for strategic planning in process industries. The DSS is built on five fundamental elements—materials, facilities, activities, storage areas, and time periods. It requires little direct knowledge of optimization techniques to be used effectively. Results based on real data from an aluminium company in India demonstrate significant potential for improvement in profits. We conclude with a comparison of similar studies in two other process industries.