Effect of various parameters on the conductivity of free standing electrosynthesized polypyrrole films

Electrical characteristics of polypyrrole films electrodeposited in different aqueous electrolyte solutions including p-toluenesulfonate, naphtalenesulfonate, nitrate, tetrafluoroborate, and perchlorate anions were investigated using the Van der Pauw procedure. The polymer films were synthesized by electrochemical oxidation at a fixed potential. Experimental parameters including the pyrrole concentration, electrolyte, applied potential and substrate were shown to affect the electrical conductivity σ of polypyrrole films. Since the substrate contributes significantly to the overall conductivity of polypyrrole-coated electrodes, the results obtained with free standing polymer films appeared more reliable. The results indicated that the p-toluenesulfonate doped PPy film showed the highest average conductivity (σ_293 K = 4.5 × 10⁵ S m^?1) whereas the perchlorate doped one produced the lowest of all the films prepared (σ_293 K = 2 × 10⁴ S m^?1).     

On the design and fabrication by two-photon polymerization of a readily assembled micro-valve

This paper reports on the conceptual design and fabrication of a complex shape, readily assembled micro check valve using the two-photon polymerization technique. The material used for the fabrication of the valve is a zirconium containing organic–inorganic hybrid photosensitive sol-gel known to exhibit negligible distortion during photopolymerization. A preliminary computational fluid dynamics study has been carried out in order to evaluate the flow performance of the valve under blood pressures exhibited in healthy human veins. The fabricated micro-valves exhibit good dimensional accuracy when compared to the CAD-created valve design and the capability of an internal moving component to perform its intended function.     

Effect of media size and mechanical properties on milling efficiency and media consumption

The effect of media size and properties on milling efficiency, media wear, and power consumption will be discussed. A predictive model has been developed and was verified by analyzing results of laboratory trials in a mineral grinding application. Recent developments in high density media capabilities for a range of feed types and particle sizes will be presented.     

Taking Advantage of Overhearing in Low Power Listening WSNs: A Performance Analysis of the LWT-MAC Protocol

LWT-MAC is a new Low Power Listening MAC protocol for WSNs designed to rapidly react to instantaneous increases of the network load. It takes advantage of overhearing by waking up all nodes at the end of a transmission to send or receive packets without needing to transmit the long preamble before. In this work, detailed analytical models of the LWT-MAC and B-MAC protocols, for both saturated and unsaturated conditions, are presented. Moreover, the key LWT-MAC parameters are optimized in order to minimize the energy consumption, constrained to obtain the same throughput as the IEEE 802.11 (CSMA/CA) MAC protocol. From the behavior of the optimal LWT-MAC parameters, a heuristic configuration is proposed. Finally, the LWT-MAC is compared to B-MAC, in both single and multi-hop scenarios, showing improvements in energy consumption, throughput and delay.     

Literature review on disruption recovery in the supply chain*

Recent research underlines the crucial role of disruption events and recovery policies in supply chains. Despite a wealth of literature on supply chain design with disruption considerations, to the best of our knowledge there is no survey on supply chain with disruptions and recovery considerations. We analyse state-of-the-art research streams on supply chain design and planning with both disruptions and recovery considerations with the aim of relating the existing quantitative methods to empirical research. The paper structures and classifies existing research streams and application areas of different quantitative methods subject to different disruption risks and recovery measures. We identify gaps in current research and delineate future research avenues. The results of this study are twofold: operations and supply chain managers can observe which quantitative tools are available for different application areas; on the other hand, limitations and future research needs for decision-support methods in supply chain risk management domains can be identified.     

Photographic Miscarriage

Abstract

Henrique Fleiuss (born 1823 in Cologne, died 1882 in Rio de Janeiro) studied literature in Cologne and natural sciences as well as music in Munich. He went to Brazil in 1858 at the suggestion of von Martius, the famous botanist. There, in 1859, he founded the ‘Instituto Artistico’ in partnership with his brother Carlos Fleiuss and the artist Carlos Linde.     

ELECTROMAGNETIC ENHANCEMENT OF CHEMICAL REACTIONS (Devolatilization of Char and Coal)

Abstract

Char in the microwave energy field may enhance chemical reactions by three different ways as described below: (1) directly react with elements in molecules when contacted, (2) create free radicals when the gas molecules contact char,and (3) provide heat to adjacent solid particles. To understand the interactions between char and microwave energy, we first investigated the microwave energy absorption by char and also by the mixture of char and coal at various apparent bed temperatures and various ratios of coal to char in the mixture.

The experimental results clearly demonstrated that pyrolysis products are excellent absorbents of the microwave energy. To enhance the pyrolysis rate of coal with the microwave energy, it was necessary to add char that increased energy absorption rate. Coal/char mixture pyrolysis started immediately when the microwave energy was applied. Also, microwave energy absorption rate increased to 73% of input power. When coal concentration in the coal/char mixture exceeded 50%, energy absorption rate decreased to 54% of input power. Without char, coal was not pyrolyzed with the microwave energy (550 W) applied for 60 minutes.     

High current superconductors for DEMO

In the assumption that DEMO will be an inductively driven tokamak, the number of load cycles will be in the range of several hundred thousands. The requirements for a new generation of Nb₃Sn based high current conductors for DEMO are drafted starting from the output of system code PROCESS. The key objectives include the stability of the DC performance over the lifetime of the machine and the effective use of the Nb₃Sn strand properties, for cost and reliability reasons. A preliminary layout of the winding pack and conductors for the toroidal field magnets is presented. To suppress the mechanism of reversible and irreversible degradation, i.e. to preserve in the cabled conductor the high critical current density of the strand, the thermal strain must be insignificant and no space for micro-bending under transverse load must be left in the strand bundle. The “react-and-wind” method is preferred here, with a graded, layer wound magnet, containing both Nb₃Sn and NbTi layers. The implications of the conductor choice on the coil design and technology are highlighted. A roadmap is sketched for the development of a full size prototype conductor sample and demonstration of the key technologies.