Transport properties in polypyrrole–PVA composites: Evidence for hopping conduction

Experimental results on electrical conductivity and thermoelectric power for FeCl₃-doped polyvinyl alcohol-polypyrrole composites, with polypyrrole content exceeding the percolation threshold, are presented. The electrical conductivity is analyzed in terms of the hopping theory, whereas the thermoelectric power displays a metallic-like dependence. A model involving both the intrinsic resistance of the fibrils (V.R.H. hopping mechanisms) and the resistance of the junctions between fibrils (fluctuations-induced tunneling conduction) has been retained.     

Puffing of Okara/Rice Blends Using a Rice Cake Machine

ABSTRACT: Okara is the insoluble byproduct of soymilk and tofu manufactures. It is cheap, high in nutrients, and possesses great potential to be applied to functional human foods. In this study, a puffed okara/rice cake product was developed with blends of okara pellets and parboiled rice. Consumer preference and acceptance tests were conducted for the product. Okara pellets were prepared by grinding the strands obtained from extruding a mixture of dried okara and rice flour (3:2, w/w) with a twin‐screw extruder. Okara pellets and parboiled rice were blended in 4 ratios, 90:10, 70:30, 40:60, and 0:100 (w/w), and tempered to 14% and 17% moisture. The blends were puffed at 221, 232, and 243 °C for 4, 5, or 6 s. The okara/rice cakes were evaluated for specific volume (SPV), texture, color, and percent weight loss after tumbling. Overall, the decrease in okara content and increase in moisture, heating temperature and time led to greater specific volume (SPV) and hardness, lighter color, and lower percent weight loss after tumbling. The consumer tests indicated that the okara/rice cake containing 70% okara pellets was preferred and the 90% one was liked the least. The possible drivers of liking for the puffed okara/rice cakes could be the okara content, hardness, SPV, bright color, and percent weight loss after tumbling.     

DNA nanorobotics

This paper presents a molecular mechanics study of nanorobotic structures using molecular dynamics (MD) simulations coupled to virtual reality (VR) techniques. The operator can design and characterize through molecular dynamics simulation the behavior of bionanorobotic components and structures through 3D visualization. The main novelty of the proposed simulations is based on the mechanical characterization of passive/active robotic devices based on double stranded DNA molecules. Their use as new DNA-based nanojoint and nanotweezer are simulated and results are discussed.     

Free vibration analysis of solar functionally graded plates with temperature-dependent material properties using second order shear deformation theory

Second-order shear deformation theory (SSDT) is employed to analyze vibration of temperature-dependent solar functionally graded plates (SFGP’s). Power law material properties and linear steady-state thermal loads are assumed to be graded along the thickness. Two different types of SFGP’s such as ZrO₂/Ti-6Al-4V and Si₃N₄/SUS304 are considered. Uniform, linear, nonlinear, heat-flux and sinusoidal thermal conditions are imposed at the upper and lower surface for simply supported SFGPs. The energy method is applied to derive equilibrium equations, and solution is based on Fourier series that satisfy the boundary conditions (Navier’s method). Non-dimensional results are compared for temperature-dependent and temperature-independent SFGP’s and validated with known results in the literature. Numerical results indicate the effect of material composition, plate geometry, and temperature fields on the vibration characteristics and mode shapes. The results obtained using the SSDT are very close to results from other shear deformation theories.     

Reduction of Brochothrix thermosphacta and Salmonella Serotype Typhimurium on Vacuum-Packaged Fresh Beef Treated with Nisin and Nisin Combined with EDTA

ABSTRACT: The effect of nisin and nisin/EDTA followed by vacuum packaging on the reduction of Brochothrix thermosphacta and Salmonella typhimurium counts on beef was investigated. Beef cubes, inoculated with either bacteria, were dipped in nisin, or nisin combined with EDTA solutions, vacuum packaged, and stored at 4 °C for up to 25 d. Growth of B. thermosphacta was completely inhibited by nisin and nisin/EDTA by up to 6.76 log₁₀ CFU/ml. However, neither treatment showed significant effects against S. Typhimurium. Thus, nisin or nisin/EDTA treatment, followed by vacuum packaging under refrigerated conditions could increase the shelf life of fresh beef by inhibiting the growth of B. thermosphacta , an important spoilage organism in beef.     

Effects of hydrothermal ageing on the thermal behaviour of poly(vinyl chloride) filled with wood flour

The hydrothermal ageing of wood‐flour‐filled PVC produced by dry‐blending in a high‐speed mixer in the presence of a plasticizer and other processing additives was carried out to investigate its thermal behaviour, and the results obtained were compared with those for the unfilled material. The dry‐blended compounds were prepared as films by a calendering process. The accelerated hydrothermal ageing was carried out by immersing the samples in boiling water at 100 °C for 110 h. The thermal behaviour of the reference and the aged samples in water was characterized by differential scanning calorimetry (DSC) and determination of the weight changes. The study has shown that during hydrothermal ageing, the samples from the whole formulations absorbed water, for instance, for 30 wt% filled PVC (F30), 16 wt% of water absorption was obtained, while this was only 2.2 wt% for unfilled PVC (F0). It was also noticed that the formulations filled with wood flour up to 10 wt% exhibited similar water absorption kinetics, i.e. the water was mostly absorbed during the first 50 h and the amount absorbed was less than 5 wt%. On the other hand, the 30 wt% filled samples regularly absorbed water up to almost 16 wt% after 100 h of immersion. The DSC data showed that hydrothermal ageing significantly affected the onset temperature of decomposition (T_d) of the unfilled samples by decreasing this temperature from 228 to 215 °C. For the 30 wt% filled samples, only additive migration was observed, while the T_d remained almost unchanged. Furthermore, from the DSC data, processability of the 30 wt% filled PVC samples at elevated temperatures, i.e. 180 to 200 °C was shown. Copyright © 2004 Society of Chemical Industry     

Housing allocation and ethnic minority groups: The effects of different housing allocation models on Moroccan households in two Dutch cities

In the Netherlands, housing allocationsystems have a long history. Radical changeswhich have transformed households looking for ahome into active rather than passive consumershave occurred since the beginning of the 1990s.In the more traditional distribution models ofhousing allocation, households registered andthen had to wait for months, or even years,before the municipality or the housingassociation offered them a dwelling; in themore modern supply models, households areexpected to be active in seeking a new home. Todate, the possible differential effects of thetwo housing allocation models for minorityethnic groups have not been assessed. With thehelp of an empirical research study ofMoroccans in two Dutch middle-sized cities withdifferent allocation models, this paper seeksto fill this gap.     

Misalignment effects on steady‐state and dynamic behaviour of compliant journal bearings lubricated with couple stress fluids

This work concerns the steady‐state and dynamic analysis of misaligned compliant journal bearings considering the effects of couple stresses arising from the lubricant blended with polymer additives. Based on the Stokes micro‐continuum theory, a modified form of the Reynolds equation is derived. The displacement field at the fluid film–bearing liner interface due to pressure forces is determined using the elastic thin liner model. The effects of the misalignment and the couple stress parameters on static and dynamic performances such as pressure distribution, load‐carrying capacity, power loss, side leakage flow, misalignment moment, critical mass and whirl frequency are presented and discussed. Copyright © 2008 John Wiley & Sons, Ltd.