Multipod znO nanoforms: low temperature synthesis and characterization

ZnO nanotetrapods were synthesized by a simple thermal evaporation of Zn powder at a relatively low temperature approximately 600 degrees C. The tetrapods have four legs with hexagonal cross-section. Interpenetrating growth was observed in some of these nanotetrapods. Multipod ZnO nanoforms were produced at higher temperature. The optical characterizations such as optical absorbance, photoluminescence and Raman spectroscopy reveal excellent crystal qualities of these nanoforms. The field emission studies indicated that these nanoforms could be utilized in field emission based devices.     

Setting planned orders in master production scheduling under demand uncertainty

For single end-product master production scheduling with time-varying demand uncertainty and supply capacity, we study approaches to set replenishment quantities over the planning horizon. We present a stochastic programming model along with a simulation-based optimisation and two traditional approaches for setting order quantities. We compare these approaches to two new methods: gamma approximation and safety stock search. Computational experiments show that the gamma approximation and safety stock search perform well in terms of holding and shortage costs, with expected total cost on average, respectively, within 0.06% and 0.66% of the optimal from the stochastic program. On average, the two traditional approaches incur 12% and 45% higher cost than optimal. We provide managerial insights on the effects of parameters such as demand coefficient of variation (cv), utilisation, and target service level on the optimal total cost, the corresponding fill rate, and the relative performance of the approaches. We find that, for finite-normal demand, on average, the impact of target service level on cost is larger than that of demand cv, whose impact is larger than utilisation, except at high utilisation. We illustrate that, when demand is not normal, the gamma approximation significantly outperforms the existing normal approximation from Bollapragada and Rao (2006 Bollapragada, R and Rao, US. 2006. Replenishment planning in discrete-time, capacitated, non-stationary, stochastic inventory systems. IIE Transactions, 38(7): 583–595.  [Google Scholar]).     

Properties of Squeezed Binomial States and Squeezed Negative Binomial States

Abstract

The effect of squeezing on binomial states and on negative binomial states is studied in terms of second-order correlation functions and quasi-probabilities of Wigner and Q-functions. The photon number distribution of these states is also discussed. The results presented for squeezed binomial (negative binomial) states may be useful for studying a transition from squeezed coherent states to squeezed number (quasi-thermal) states.     

Role of gamma radiation and EGDMA on the physico–mechanical properties of jute fabrics/polypropylene composites

Jute fabrics reinforced polypropylene (PP) composites (45 wt % fiber) were prepared by compression molding and their mechanical properties were investigated. Both jute fabrics and PP sheets were treated with gamma radiation (250–1,000 krad dose) at a rate of 350 krad/h. Irradiated jute fabrics were soaked into ethylene glycol dimethacrylate (EGDMA) solutions (5–40% by weight) and cured in an oven at different temperatures (40–100°C) for 60 min. The percentage of polymer loading (PL) was evaluated and found that 20% EGDMA‐treated jute fabrics contains the highest PL. Composites made of 20% EGDMA‐treated jute fabrics were studied further. It was found that the treatment using the EGDMA improved the mechanical properties of the composites significantly. Scanning electron microscopy and aging properties of untreated and treated composites were performed. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers     

UV nanoimprint lithography of sub-100 nm nanostructures using a novel UV curable epoxy siloxane polymer

We reported the replication of sub-100 nm nanostructures by an ultraviolet (UV) nanoimprint lithography (NIL) technique. We used a novel UV curable epoxy siloxane polymer as the NIL resist to achieve features as small as 50 nm. The polymeric soft molds for the NIL were fabricated by casting toluene diluted poly(dimethyl-siloxane) (PDMS) on the hydrogensilsesquioxane (HSQ) hard mold. The NIL results were characterized by using a scanning electron microscope and an atomic force microscope. Our results illustrate that, with the epoxy siloxane resist, the 50 nm HSQ features on the hard mold can be successfully replicated using PDMS soft molds.     

Numerical model of longitudinal wave scattering in polycrystals

The scattering of elastic waves in polycrystalline materials is relevant for ultrasonic materials characterization and nondestructive evaluation (NDE). Ultrasonic attenuation is used widely to extract microstructural parameters such as grain size. Accurate interpretation of experimental data requires robust scattering models. Such models typically assume constant density, uniform grain size, and ergodicity hypotheses. The accuracy and limits of applicability of these models cannot be fully tested with experiments due to practical limits of real materials processing. Here, this problem is examined in terms of numerical simulations using Voronoi polycrystals that are discretized using finite elements. Wave propagation is studied by integrating the system directly in time using a planestrain formulation. Voronoi polycrystals with cubic symmetry and random orientations are used making the bulk material statistically isotropic. Example numerical results for materials with various degrees of scattering that are of common interest are presented. The numerical results are presented and compared with scattering theory for a wide range of frequencies. The numerical results show good agreement with the theory for the examples examined with evidence that the correlation function is frequency dependent. These results are anticipated to impact ultrasonic NDE of polycrystalline media.     

Electrical impedance spectroscopic study of mandarin orange during ripening

Electrical impedance spectroscopy (EIS) as non-destructive investigation has been conducted to study the electrical impedance variations during ripening of mandarin orange. The objective of the work is to study the electrical impedance variations and variations in weight of the orange fruit with different ripening state. Electrical equivalent circuit has been modeled relative to the Nyquist plot obtained during the ripening of orange by non-linear curve fitting technique. EIS studies on orange fruit have been conducted by applying a small amount of alternating current through an array of Ag/AgCl electrodes attached to the orange fruit. The impedance and phase angles of orange fruit are measured at frequency sweep from 50 Hz to 1 MHz for 100 frequency points. The results revealed that the impedance, real part and imaginary part of the impedance all are increased and the weight of orange are decreased with the increase in ripening state. It is observed that the electrical equivalent circuit of orange fruit contains a constant phase element.     

Improved scatterer property estimates from ultrasound backscatter using gate-edge correction and a pseudo-Welch technique

Quantitative ultrasound (QUS) techniques have been widely used to estimate the size, shape and mechanical properties of tissue microstructure for specified regions of interest (ROIs). For conventional methods, an ROI size of 4 to 5 beamwidths laterally and 15 to 20 spatial pulse lengths axially has been suggested to estimate accuracy and precision better than 10% and 5%, respectively. A new method is developed to decrease the standard deviation of the quantitative ultrasound parameter estimate in terms of effective scatterer diameter (ESD) for small ROIs. The new method yielded estimates of the ESD within 10% of actual values at an ROI size of five spatial pulse lengths axially by two beamwidths laterally, and the estimates from all the ROIs had a standard deviation of 15% of the mean value. Such accuracy and precision cannot be achieved using conventional techniques with similar ROI sizes.     

Antiamoebic activity of Piper longum fruits against Entamoeba histolytica in vitro and in vivo

Proposed changes in postgraduate surgical training must be seen in the context of changes being implemented in medical schools. The reorganization of discipline-based departments into large units of biomedical science; the reduction in time allotted to anatomy, particularly to dissection by students; the development of integrated courses with multidisciplinary examinations in which poor performance in anatomy can be compensated by good marks in other subjects; the decline in staff numbers (faculty) with expertise in human anatomy and corresponding enthusiasm for teaching it; and the loss of demonstratorships available to surgical trainees are all factors that leave today's medical graduates who embark upon surgical training programs poorly equipped in their knowledge of anatomy. This deficiency is not easily remedied by the proposed changes in Basic Surgical Training and is not adequately identified by the examination arrangements. It is argued that a structured oral examination with a wide spectrum of components, including dissections, living and surface anatomy, osteology, radiographs and scans, and microanatomy, would be the best way of assessing the familiarity of candidates with anatomy and their suitability to proceed to Higher Surgical Training.     

Fabrication of SnS2 flower like nanoflake assemblies through thermal evaporation

Uniform as well as flower like patterns of SnS2 nanoflakes were produced by a thermal evaporation process. Interpenetrating phenomenon was observed between the individual nanoflakes during the course of their lateral growth. The interpenetrating growth and controlled vapor concentration as well as the substrate temperature leads to the formation of flower like assemblies of SnS2 nanoflakes. Morphology and growth mechanism of the nanostructures were studied by scanning electron microscopic observations at different stages of the nanoflake growth. The produced nanoflakes were characterized by X-ray diffraction, scanning and transmission electron microscopy, and Raman spectroscopic measurements. SnS2 nanoflakes were perfectly single crystalline and growth direction of the nanoflakes was along the [101]-lattice plane.