Analysis of SiC fibres and composites using Raman microscopy

The application of Raman spectroscopy in the analysis of the microstructure of SCS-6 silicon carbide fibres using a Renishaw Raman microscope is described. It is demonstrated that the technique allows a detailed study to be made of the point-to-point variation in microstructure across a fibre section. It has been possible to monitor the variation of the concentration of SiC and carbon in the fibre microstructure and to detect differences in the forms of carbon present. It is also shown that Raman spectroscopy can be used to follow the micromechanics of both the deformation of silicon carbide fibres and of the fibres within a model composite. Well-defined Raman spectra have been obtained from a variety of Nicalon and Tyranno fibres and the positions of the Raman bands shown to shift on the application of stress or strain. From such stress-induced Raman band shifts, the point-to-point variation of axial fibre stress or strain along an individual fibre in an epoxy matrix can be determined. An example is given of the use of the technique to map the distributions of axial fibre strain in a Nicalon/epoxy fragmentation test specimen and to model the failure processes at the fibre/matrix interface.     

Effects of myosin light chain kinase inhibitors on carbachol-activated nonselective cationic current in guinea-pig gastric myocytes

The effects of myosin light chain kinase inhibitors on muscarinic stimulation-activated nonselective cationic current (ICCh) in guinea-pig gastric antral myocytes were studied using the whole-cell patch-clamp technique. ICCh was induced by carbachol (CCh, 50 microM) at a holding potential of -30 mV or -60 mV. ML-7, a chemical inhibitor of myosin light chain kinase (MLCK), inhibited ICCh concentration dependently in a reversible manner (53 +/- 8.6% at 1 microM, mean +/- SE, n = 11). In addition, amplitudes of ICCh were only 37 +/- 2.7% of the daily control values following the addition of a peptide inhibitor of MLCK to the pipette solution. On the other hand, ML-7 had an inhibitory effect on voltage-operated Ca2+ channel current. The peak value of Ba2+ current at 0 mV was reduced to 35 +/- 7.4% (n = 9) by 3 microM of ML-7. As ICCh is known to have an intracellular Ca2+ dependence, we tried to exclude the possibility that ML-7 inhibited ICCh indirectly via suppression of Ca2+ current and the similar inhibitory effects of ML-7 on ICCh were confirmed under the following conditions: (1) clamp of membrane potential at -60 mV; (2) clamp of intracellular [Ca2+] to 1 microM by 10 mM BAPTA; (3) pre-inhibition of Ca2+ channel by verapamil. Different from the effects on ICCh, ML-7 barely inhibited the same cationic current induced by guanosine 5'-O-(3-thiotriphosphate) (GTP[gammaS], 0.2 mM) in the pipette solution. These results suggest that a Ca2+/calmodulin-MLCK-dependent pathway can modulate the activation of ICCh in guinea-pig gastric antral myocytes.     

A two-dimensional transmission line matrix microwave fieldsimulator using new concepts and procedures

A two-dimensional field simulator for microwave circuit modeling is described. It incorporates a number of recently developed concepts and advanced transmission line matrix (TLM) procedures. In particular, a discrete Green's function concept based on P.B. John's and K. Akhlarzad's time-domain diakoptics is realized, providing a high level of processing power through modularization of large structures at the field level, simulation of wideband matched loads or absorbing walls, modeling of frequency-dispersive boundaries in the time domain, and large-scale numerical preprocessing of passive structures. Nonlinear field modeling concepts are also implemented in the TLM field simulator. It can analyze two-dimensional circuits of arbitrary geometry containing both linear and nonlinear media. The circuit topology is input graphically. Both time-domain and frequency-domain responses can be computed and displayed. The capabilities and limitations of the simulator are discussed, and several microstrip and waveguide components are modeled to demonstrate its important features     

Measurement and calculation of swelling equilibria for water/poly(acrylamide-sodiumallylsulfonate) systems

Superabsorbent poly(acrylamide-sodiumallylsulfonate) was synthesized from acrylamide (AM) and sodiumallylsulfonate (SAS) by a solution polymerization method. N,N’-methylenebisacrylamide (BIS) was used as the crosslinker; potassium persulfite (PP) and N,N,N’,N’-tetra-methylenediamine (TMEDA) were used as the redox initiator during the synthesis. The absorption capacities of the synthesized superabsorbent poly(AM-SAS) were repeatedly measured to obtain the optimal poly(AM-SAS) according to the variations of monomer concentration at 298.15 K. Its maximal absorption capacity appeared as 811 times at 0.1 mol/L among from 0.01 mol/L to 0.16 mol/L of SAS concentrations. The swelling equilibria at those conditions from 298.15 K to 318.15 K were measured and used to estimate the parameters by correlating with the Flory-Huggins model. The swelling behavior could be described by the parameters and the calculated values agreed satisfactorily with the experimental data.     

Public willingness to pay a premium for uni‐material beverage container in Korea: a contingent valuation study

The use of uni‐materials can reduce the total waste generation by a high recycling rate. This study assesses the public's willingness to pay (WTP) a premium for the uni‐material beverage container (UBC) in Korea using a specific case of bottled mineral water in polyethylene terephthalate (PET). For this purpose, a contingent valuation (CV) survey of 1000 consumers was conducted to derive the additional WTP for the mineral water in UBC instead of that in non‐UBC. Given that the average price of the mineral water (500 mL) in non‐UBC was KRW 1000 (USD 0.88), the mean additional WTP a premium for that in UBC was estimated to be KRW 107 (USD 0.09). This value amounts to 10.7% of price of the mineral water in non‐UBC and can be interpreted as the public value of the UBC. The consumers in Korea are ready to pay a significant premium for UBCs.     

Preparation and catalytic activity of K4Zr5O12 for the oxidation of soot from vehicle engine emissions

Pure phase K₄Zr₅O₁₂ is synthesized via solid state method in the present work. Various K/Zr ratios and temperatures are applied, and the synthesis process is investigated in detail by means of X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and X-ray photoelectron spectroscopy. Its catalytic activity for soot oxidation is studied by temperature programmed oxidation with different types of soot/catalyst contacts. It is revealed that K₄Zr₅O₁₂ is very active in the presence of 2–10% O₂ for both tight and loose contacts (T_p(tight) = 335 °C, T_p(ethanol) = 355 °C and T_p(shaking) = 370 °C). Thermal stability study shows that K₄Zr₅O₁₂ is highly stable up to at least 900 °C.     

High-Efficiency Blue Emitting Phosphorescent OLEDs

In this paper, we will show our latest results on high-efficiency blue phosphorescent organic light-emitting diodes (PHOLEDs). Effects of triplet exciton confinement, exciton energy transfer and charge trapping, and charge balance on iridium(III)bis [(4,6-di-fluorophenyl)-pyridinato-N,C2'] picolinate (FIrpic)-based blue PHOLEDs will be presented. By optimizing the aforementioned device parameters, a high-efficiency blue PHOLED with 59 cd/A (48 lm/W at 100 cd/m²) was demonstrated.     

Effects of supplied gas humidity change on PEFC transient power generation

Polymer electrolyte fuel cells (PEFCs, PEMFCs) are gaining increasingly more attention as clean and efficient energy‐conversion devices. Vapor and liquid transport has a strong impact on the power generation characteristics and efficiency of PEFCs, and so proper water management is needed for efficiency and durability. However, water transport factors are not well understood, particularly during unsteady operation—often the case in vehicles and distributed stationary power generators. In this study, to understand and generalize the effects of local water transport on PEFC performance, transient mass transport characteristics inside a PEFC were investigated experimentally and numerically. For this purpose, we developed an unsteady two‐dimensional numerical model based on mass‐ and charge‐conservation equations in the channel, gas diffusion layer (GDL), and membrane electrode assembly (MEA). As necessary parameters for model development, we measured the water content of the MEA, the membrane resistivity, the activation overvoltage, overall mass transfer coefficient, and so on. The membrane resistivity greatly increases as the relative humidity decreases. The activation overvoltage is also affected by the relative humidity, and not only by the current density and oxygen activity. Current load and voltage changes are frequently used as PEFC transient inputs, but lead to very complicated and intractable phenomena such as changes in the amount of generated water and electro‐osmosis, state of the electrical double layer, and so on. Hence, stepwise changes in the relative humidity of the supplied gas were adopted in this study. The experimental and numerical transient responses were in good agreement under most operating conditions, and the reliability of our measurement methods for the water transport properties and our numerical model were confirmed. Here we discuss the dominant factor in the transient responses, and conclude that the transport resistance at the PEM–GDL interface is the largest and most dominant factor in a relatively dry state under unsteady operating conditions. © 2011 Wiley Periodicals, Inc. Heat Trans Asian Res; Published online in Wiley Online Library ( wileyonlinelibrary.com/journal/htj ). DOI 10.1002/htj.20371     

Agent-based flight planning system for enhancing the competitiveness of the air cargo industry

In this paper, we propose a multi-agent-based framework to facilitate process automation for the air cargo industry. The focus is on enhancing two labor-intensive flight planning processes, namely cargo consolidation and equalization. By employing a software agent-based flight planning module, which is linked with an RFID-based warehouse management system, air cargo items received at a freight forwarder’s warehouse can be processed more efficiently and flight plans can be generated automatically. In particular, we employ agents equipped with simulated annealing optimization engines to handle the time-consuming tasks of optimization. By doing so, the latest flight plans can be generated more efficiently. The system has been evaluated experimentally by both simulated and real-life data. The results are encouraging. For example, operation steps that normally require over 30 minutes to complete can now be carried out in as quickly as two minutes, and produce a better solution.