A fuzzy analytic hierarchy process approach for assessing national competitiveness in the hydrogen technology sector

As it is more environmentally sound and friendly than conventional energy technologies that emit carbon dioxide, hydrogen technology can play a key role in solving the problems caused by the greenhouse gas effect and in coping with the hydrogen economy. Numerous countries around the world, including Korea, have increasingly focused on R&D where hydrogen technology development is concerned. This paper focuses on the use of the fuzzy analytic hierarchy process (fuzzy AHP), which is an extension of the AHP method and uses interval values to reflect the vagueness of human thought, to assess national competitiveness in the hydrogen technology sector. This analysis based on the AHP and fuzzy AHP methods revealed that Korea ranked 6th in terms of national competitiveness in the hydrogen technology sector.     

Modeling of the capacity loss of a 12 V automotive lead-acid battery due to ageing and comparison with measurement data

One-dimensional modeling was carried-out to predict the capacity loss of a 12 V automotive lead-acid battery due to ageing. The model not only accounted for electrochemical kinetics and ionic mass transfer in a battery cell, but also considered the anodic corrosion of lead in sulfuric acid. In order to validate the modeling, modeling results were compared with the measurement data of the cycling behaviors of the lead-acid batteries having nominal capacity of 68 Ah that are mounted on the automobiles manufactured by Hyundai Motor Company. The cycling was performed under the protocol of the constant-current discharge and the constant-voltage charge. The discharge rate of C/3 was used. The range of state of charge was between 1 and 0.85. The voltage was kept constant at the gassing voltage until the charge current tapered to 10 mA. The retention capacity of the battery was measured with C/3 discharge rate before the beginning of cycling and after every 40 cycles of cycling. The modeling results were in good agreement with the measurement data.     

Hydrodynamic characteristics of a circulating fluidized bed

In a circulating fluidized bed (7.8 cm-ID x 260 cm-high), flow regime of coal-air system at room temperature has been determined. Bituminous coal particles used were either 0.73 mm or 1.03 mm in the mean diameter having density of 1400 Kg/m³. The transition velocities from bubbling to turbulent beds and the transport velocities between turbulent and fast beds have been determined. The resulting transition velocities between bubbling and turbulent beds were 103 cm/s for 0.73 mm and 130 cm/s for 1.03 mm coal particles, respectively. The transport velocities between turbulent and fast beds were 180 and 209 cm/s for 0.73 and 1.03 mm particles, respectively. In addition, chocking velocities were determined at different solid feeding rates. The resulting values were in the range of 2.55-2.65 m/s for 0.73 mm particle and of 2.77-2.84 m/s for 1.03 mm particle, respectively. The published literature data of the transition velocity between bubbling and turbulent bed have been correlated with particle properties.     

Emulsion polymerized polyaniline synthesized with dodecylbenzene-sulfonic acid and its electrorheological characteristics: Temperature effect

Dodecylbenzene-sulfonic acid (DBSA)-doped polyaniline (PANI) was prepared by emulsion polymerization, where DBSA was used as both an emulsifier and a dopant. The chemical structure and morphology of the DBSA were examined via FT-IR and SEM, respectively. Electrorheological (ER) properties of DBSA-doped PANI particles dispersed in silicone oil were studied under different operating temperatures and an applied electric field. Shear stress data as a function of shear rate fitted quite well with the Cho-Choi-Jhon (CCJ) shear stress model. Both deduced static and dynamic yield stresses were found to be collapsed into a universal scaling function. Furthermore, the Cole-Cole plot and the dielectric spectra gave relaxation times of the ER systems for different operating temperatures of dielectric measurements, confirming the correlation of dielectric properties with ER performance.     

Mechanical and thermal properties of waste silk fiber‐reinforced poly(butylene succinate) biocomposites

This article reports the mechanical and thermal properties of poly(butylene succinate) (PBS) biocomposites reinforced with industrially available waste silk fibers, fabricated with varying fiber contents and lengths. The result indicates that use of waste silk fibers may be a potential as reinforcement for effectively improving the static and dynamic mechanical properties of a biodegradable polymer matrix resin, depending on the waste silk fiber content and length in the present biocomposite system. The “as‐separated” waste silk/PBS biocomposites showed the maximum tensile and flexural properties at a fiber loading of 40 wt %, and the “chopped” waste silk/PBS biocomposites showed the optimal strength and modulus with waste silk fibers of 12.7 mm length. The chopped waste silk fibers play a more contributing role in improving the mechanical properties of waste silk/PBS biocomposites than the as‐separated waste silk fibers at a fixed fiber loading. Above the glass transition temperature, the storage modulus of waste silk/PBS biocomposites was significantly greater than that of PBS resin, especially in the higher temperature region. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4972–4980, 2006     

Temperature/pH‐sensitive comb‐type graft hydrogels composed of chitosan and poly(N‐isopropylacrylamide)

Comb‐type graft hydrogels, composed of chitosan and poly(N‐isopropylacrylamide) (PNIPAAm), were prepared to manifest rapid temperature and pH sensitivity. Instead of directly grafting the NIPAAm monomer onto the chitosan chain, semitelechelic PNIPAAm with carboxyl end group was synthesized by radical polymerization using 3‐mercaptopropionic acid as the chain‐transfer agent, and was grafted onto chitosan having amino groups. The comb‐type hydrogels were prepared with two different graft yields and grafting regions, such as surface‐ and bulk‐grafting, and then compared with a chitosan hydrogel. The synthesis of telechelic PNIPAAm and the formation of amide group were confirmed by using FTIR spectroscopy and gel permeation chromatography. Results from the water state and thermal stability revealed that the introduction of the PNIPAAm side chain disturbed the ordered arrangement of the chitosan molecule, resulting in an increase in the equilibrium water content. Comb‐type graft hydrogels showed rapid temperature and pH sensitivity because of the free‐ended PNIPAAm attached to the chitosan main chain and the chitosan amino group itself, respectively. In particular, the surface graft hydrogel maintained its dimension at low pH, although the chitosan main chain was not crosslinked, whereas chitosan and bulk graft hydrogel were dissolved as a result of the coating effect of pH‐independent PNIPAAm. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2612–2620, 2004     

Lipase‐catalysed production and chemical composition of diacylglycerols from soybean oil deodoriser distillate

Diacylglycerols (DAG) were enzymatically produced by lipase‐catalysed esterification of glycerol with fatty acids from soybean oil deodoriser distillate (SODD). Effects of reaction parameters such as reaction time, temperature, enzyme type, enzyme load, substrate molar ratio and water content, as well as the effect of molecular sieves as water adsorbent were studied. Lipozyme RM IM was determined to be the most effective among the lipases screened. The following conditions yielded 69.9% DAG (all percentages are wt/wt): 4 h reaction time, 65 °C reaction temperature, 10% Lipozyme RM IM, 2.5:1 fatty acid to glycerol molar ratio, and 30% molecular sieves. DAG synthesis of 11.9% was still observed at 10% water content. After purification, the product oil contained 86.3% DAG. This oil consisted predominantly of 1,3‐diolein (19.1%), 1‐oleoyl‐3‐linoleoyl‐glycerol (18.2%) and 1‐oleoyl‐2‐linoleoyl‐glycerol (16.6%). The fatty acid profile of the oil was similar to that of refined, bleached and deodorised (RBD) soybean oil. The % ratio of 1,3‐ to 1,2‐positional isomers of DAG was at 56:44.     

Methemoglobin Is an Endogenous Toll-Like Receptor 4 Ligand—Relevance to Subarachnoid Hemorrhage

Neuroinflammation is a well-recognized consequence of subarachnoid hemorrhage (SAH), and may be responsible for important complications of SAH. Signaling by Toll-like receptor 4 (TLR4)-mediated nuclear factor κB (NFκB) in microglia plays a critical role in neuronal damage after SAH. Three molecules derived from erythrocyte breakdown have been postulated to be endogenous TLR4 ligands: methemoglobin (metHgb), heme and hemin. However, poor water solubility of heme and hemin, and lipopolysaccharide (LPS) contamination have confounded our understanding of these molecules as endogenous TLR4 ligands. We used a 5-step process to obtain highly purified LPS-free metHgb, as confirmed by Fourier Transform Ion Cyclotron Resonance mass spectrometry and by the Limulus amebocyte lysate assay. Using this preparation, we show that metHgb is a TLR4 ligand at physiologically relevant concentrations. metHgb caused time- and dose-dependent secretion of the proinflammatory cytokine, tumor necrosis factor α (TNFα), from microglial and macrophage cell lines, with secretion inhibited by siRNA directed against TLR4, by the TLR4-specific inhibitors, Rs-LPS and TAK-242, and by anti-CD14 antibodies. Injection of purified LPS-free metHgb into the rat subarachnoid space induced microglial activation and TNFα upregulation. Together, our findings support the hypothesis that, following SAH, metHgb in the subarachnoid space can promote widespread TLR4-mediated neuroinflammation.     

Cure efficiency of dodecyl succinic anhydride as a cross‐linking agent for elastomer blends based on epoxidized natural rubber

Blends of a highly epoxidized natural rubber (ENR50) with unmodified natural rubber (NR) and ethylene propylene elastomers (EPDM) were produced to evaluate the mixing and curing characteristics. Dodecyl succinic anhydride was used to cross‐link the ENR50 component and the reactivity was assessed by monitoring the evolution of the torque in an oscillatory co‐axial cylinder rheometer, as well as by DSC thermal analysis. A physical model was used to obtain a single parameter for the reactivity of the system, which corresponds to the rate constant for first order curing reactions. Although the blends were thermodynamically immiscible, displaying no significant change in T_g, the components were well dispersed at microscopic level. Better mechanical properties were obtained for blends with EPDM. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41448.     

Urushiol/polyurethane–urea dispersions and their film properties

A series of aqueous polyurethane–urea (PUU) dispersions having urushiol were synthesized by in situ step polymerization of isophorone diisocyanate (IPDI), poly(ethylene glycol) (PEG, M_n = 1000 g/mol), urushiol, dimethylol propionic acid (DMPA), and ethylene diamine (EDA). Urushiol was extracted with acetone from the purified lacquer of Toxicodendron vernicifluum and the different concentrations (0, 11.8, 17.6, and 22.2 wt.% based on the total solids) of urushiol were introduced during the PU prepolymer synthesis. Thermal stability, mechanical strength, antimicrobial, and anticorrosive properties of the urushiol/PUU films were investigated in terms of urushiol concentration.