Electrical properties of electrodeposited polyaniline nanotubes

The electrical properties of polyaniline nanotubes-aluminum like Schottky diode are described. Polyaniline nanotubes (PANI) were deposited on aluminum thin films using the polarographic technique. The nanotubes were characterized by scanning electron microscopy (SEM) and UV-Vis absorption spectra. The electrical properties of the heterojunction PANI-Al were examined. The current density–voltage (J × V) profile has shown a behavior typical of Schottky diode, with ideality factor (n) of 6.76 and ϕ _b of 0.70 eV. Impedance spectroscopy data apparently shows that the resistance dominated the AC behavior of the PANI-Al system. The equivalent circuit is composed from a resistor in series with a parallel resistor–capacitor circuit. The results indicate that polyaniline nanotubes may be interesting to the development of electro-optical devices with 2D structure.     

Boron nitride nanotubes coated with organic hydrophilic agents: Stability and cytocompatibility studies

In the present study, Boron Nitride Nanotubes (BNNTs) were synthesized and functionalized with organic hydrophilic agents constituted by glucosamine (GA), polyethylene glycol (PEG)₁₀₀₀, and chitosan (CH) forming new singular systems. Their size, distribution, and homogeneity were determined by photon correlation spectroscopy, while their surface charge was determined by laser Doppler anemometry. The morphology and structural organization were evaluated by Transmission Electron Microscopy. The functionalization was evaluated by Thermogravimetry analysis and Fourier Transformer Infrared Spectroscopy. The results showed that BNNTs were successfully obtained and functionalized, reaching a mean size and dispersity deemed adequate for in vitro studies. The in vitro stability tests also revealed a good adhesion of functionalized agents on BNNT surfaces. Finally, the in vitro cytocompatibility of functionalized BNNTs against MCR-5 cells was evaluated, and the results revealed that none of the different functionalization agents disturbed the propagation of normal cells up to the concentration of 50 μg/mL. Furthermore, in this concentration, no significantly chromosomal or morphologic alterations or increase in ROS (Reactive Oxygen Species) could be observed. Thus, findings from the present study reveal an important stability and cytocompatibility of functionalized BNNTs as new potential drugs or radioisotope nanocarriers to be applied in therapeutic procedures.     

Real-time line detection through an improved Hough transform voting scheme

The Hough transform (HT) is a popular tool for line detection due to its robustness to noise and missing data. However, the computational cost associated to its voting scheme has prevented software implementations to achieve real-time performance, except for very small images. Many dedicated hardware designs have been proposed, but such architectures restrict the image sizes they can handle. We present an improved voting scheme for the HT that allows a software implementation to achieve real-time performance even on relatively large images. Our approach operates on clusters of approximately collinear pixels. For each cluster, votes are cast using an oriented elliptical-Gaussian kernel that models the uncertainty associated with the best-fitting line with respect to the corresponding cluster. The proposed approach not only significantly improves the performance of the voting scheme, but also produces a much cleaner voting map and makes the transform more robust to the detection of spurious lines.     

Aerated rock filters for enhanced nitrogen and faecal coliform removal from facultative waste stabilization pond effluents.

Facultative waste stabilization ponds in the UK, loaded at 80 kg BOD/ha day, produce effluents which comply with the European Urban Waste Water Treatment Directive (i.e., < or = 25 mg filtered BOD/l and < or = 150 mg SS/l). However, the Environment Agency of England and Wales typically requires a higher effluent quality of < or = 40 mg/l unfiltered BOD and < or = 60 mg/l SS, both on a 95-percentile basis. An ammonium-nitrogen requirement might also be applied. Traditionally, maturation ponds and reedbeds have been used to upgrade facultative pond effluents, requiring large land areas. This paper describes and compares aerated and unaerated rock filter performance for BOD, SS, nitrogen and faecal coliform removals, and highlights the land-saving opportunities as maturation ponds and reedbeds become redundant.     

VALIDATION OF PREDICTIVE AXIS CONTROL STRUCTURE WITHIN A VIRTUAL OPEN ARCHITECTURE MACHINE TOOL

This paper first presents the elaboration of a virtual machine tool within an open architecture framework, including CAM (Computer Aided Manufacturing) modules such as trajectory generation and visualization facilities. The proposed advanced controller is then introduced within this simulator. Based on predictive strategies, it appears as an excellent control alternative coupled to a simple design procedure and implementation facilities. Moreover, the resulting controller, structured under the polynomial RST form, considered as a generic formalism for any SISO (Single Input Single Output) numerical controller, fulfills the requirements towards an open architecture framework. Validation tests are achieved within this virtual environment and compared to those obtained on a real machining center under its current control structure.     

Compared to a small,supervised lab experiment,a large,unsupervised web-based experiment on a previously unknown effect has benefits that outweigh its potential costs

Research on internet-based studies has generally supported their benefits. However, that research sometimes did not directly compare internet-based to traditional delivery, often used non-experimental methods and small samples, and has not used an entirely unknown effect for the comparison to completely rule out demand characteristics. Our lab experiment (N = 180), in which participants were supervised by an experimenter, demonstrated previously unexamined effects. Both the frighteningness and disgustingness of insects made people want to kill them, and females wanted to kill the insects more than males did. There were also some interesting patterns of interaction with gender, but they were not statistically significant. However, an unsupervised, but larger, web-based experiment (N = 1301) produced the same significant main effects as the lab study, and the same patterns of interaction that had occurred at a non-significant level in the lab study occurred at a statistically significant level in the web-based study. These results add support to the finding that although web-based studies may incur risks by being unsupervised, such as some participants not being genuinely motivated to follow the instructions correctly, the risks are compensated for by the much larger sample size afforded by the web-based approach.     

Thermal Conductivity Variation with Temperature for Lead-Free Ternary Eutectic Solders

The variations of the thermal conductivity with temperature for the lead-free ternary eutectic solders Bi-42.73 wt.%Sn-1.03 wt.%Ag (Bi-Sn-Ag), Sn-3.5 wt.%Ag-0.9 wt.%Cu (Sn-Ag-Cu), Sn-6 wt.%Sb-5 wt.%Ag (Sn-Sb-Ag), Sn-42.8 wt.%Bi-0.04 wt.%Cu (Sn-Bi-Cu), and In-48.4 wt.%Sn-2.31 wt.%Ag (In-Sn-Ag) were measured using a linear heat flow apparatus. It was observed that the thermal conductivities of solid phases for the Bi-Sn-Ag, Sn-Ag-Cu, Sn-Sb-Ag, Sn-Bi-Cu, and In-Sn-Ag solders decrease linearly with increasing temperature. The thermal conductivities of the Bi-Sn-Ag, Sn-Ag-Cu, Sn-Sb-Ag, Sn-Bi-Cu, and In-Sn-Ag solders at their melting temperature were obtained as 17.89 ± 1.6 W/K-m, 49.89 ± 4.5 W/K-m, 41.96 ± 3.8 W/K-m, 20.03 ± 1.8 W/K-m, and 70.21 ± 6.3 W/K-m, respectively. The thermal temperature coefficients for the Bi-Sn-Ag, Sn-Ag-Cu, Sn-Sb-Ag, Sn-Bi-Cu, and In-Sn-Ag solders were also determined to be ?2.894 × 10^?3 K^?1, ?0.907 × 10^?3 K^?1, ?1.246 × 10^?3 K^?1, ?2.638 × 10^?3 K^?1, and ?1.250 × 10^?3 K^?1, respectively, from plots of thermal conductivity versus temperature.     

Infrared and microwave shielding of transparent Al-doped ZnO superlattice grown via atomic layer deposition

The system of atomic-layer Al-doped ZnO (AZO) superlattice is rather interesting in that it exhibits a “bipolar transparency,” as it is transparent in the visible and opaque in the infrared to microwave. Here, we report on our measurements of the infrared and microwave shielding properties of thin films (~150 nm) of an Al-doped ZnO superlattice grown via atomic layer deposition (ALD). These optically transparent conductive oxide thin films have large DC electrical conductivity (>50,000 S/m) which increases with Al doping. Their infrared optical properties are well described by a free-electron (Drude) model, which results from the very large carrier concentrations (>3 × 10²⁰ cm^?3) resulting from AlO _x -heterolayer-doping. It is found that increasing Al concentrations lead to an increase in the relaxation energy which, however, is not strong enough to cause the plasma frequency to red-shift. Microwave shielding properties were investigated in the frequency range from 1 to 30 GHz, and shielding efficiencies as high as ~22 dB were observed, confirming that the free-electron picture extends into the microwave regime. The dynamic conductivity in the microwave range was found to correspond well to the measured DC values. Due to their high electrical conductivity and high microwave shielding efficiency in thin film format, these materials may be desirable for applications in transparent electronics, optically transparent EMI shielding coatings, and heat/microwave reflecting coatings for windows.     

Friction factors of power-law fluids in chevron-type plate heat exchangers

In the present work laminar flows of Newtonian and power-law fluids through cross-corrugated chevron-type plate heat exchangers (PHEs) are numerically studied in terms of the geometry of the channels. The plates area enlargement factor was a typical one (1.17), the corrugation angle, β, varied between 30° and 60° and the flow index behaviour, n, between 0.25 and 1. Single friction curves fRe_g = K for both Newtonian and non-Newtonian fluids are proposed for each β by developing an adequate definition of the generalised Reynolds number, Re_g. The coefficient K compares well with experimental data, for all (seven) values of β, and depends on the tortuosity coefficient, τ. It was found that, for each β, τ decreases with the decrease of n. Food fluids are frequently processed in PHEs and usually behave as non-Newtonian fluids. This study can be useful in engineering applications as well as in the characterization of transport phenomena in PHEs.     

Cork based composites using polyolefin’s as matrix: Morphology and mechanical performance

The cork industry produces high amounts of cork powders resulting from the final stages of cork processing or resulting from existing cork products. Usually these powders are burned and served to boilers in industrial processes. The main goal of this work is to transform this cork sub-product into a highly value composite product. The real value is dependent on the mechanical performance of this product. Thus the mixture between cork and thermoplastics, particularly the improvement of interfacial bonding, is an important topic, which needs to be developed. The interfacial affinity can be greatly increased, applying superficial modification of one of the components, or by the use of coupling agents. In this work, a high amount of cork powder (50 wt.%) from different origins combined with different thermoplastic materials using melt based processes has been examined. Pultrusion was used to produce pellets and compression moulding to obtain boards to determine its properties. Coupling agents based on maleic anhydride (2 wt.%) improved the tensile strength successfully, while the cork powder has an a important role in the stiffness. The morphology of the surface fractures indicated a good dispersion of the cork and a good adhesion between both phases. Thermal properties of the composites disclosed a nucleating effect promoted by cork.