Steam reforming of n-hexadecane over noble metal-modified Ni-based catalysts

Steam reforming of n-hexadecane, a main constituent of diesel, over noble metal-modified Ni-based hydrotalcite catalyst was carried out in a temperature range of 700–950 °C, at an atmospheric pressure with space velocity of 10,000–100,000 h⁻¹ and feed molar ratio of H₂O/C = 3.0. The catalysts were prepared by a co-precipitation and dipping methods. The noble metal-modified Ni-based hydrotalcite catalyst displayed higher resistance for the sintering of active metal than the Ni-based hydrotalcite catalyst prepared by the conventional method. It was found that the Rh-modified Ni-based catalysts showed high resistance to the formation of carbon compared to Ni-based catalysts. The results suggest that Rh-modified Ni-based catalyst can be applied for the steam reforming (SR) reaction of diesel.     

Zirconium mesostructures immobilized in calcium alginate for phosphate removal

Eutrophication caused by the excessive supply of phosphate to water bodies has been considered as one of the most important environmental problems. In this study, the powder of zirconium mesostructure (ZM), which was prepared with the template of surfactant, was immobilized in calcium alginate for practical application and the resulting material was tested to evaluate the phosphate removal efficiency. Sorption isotherms and kinetic parameters were obtained by using the entrapped ZM beads with 30 to 60% of ZM. The maximum sorption capacity increased with the higher ZM content. Q _max in Langmuir isotherm was 51.74 mg/g for 60% of ZM with 7 mm of size. The smaller the particle size of the ZM beads, the faster the rate of phosphate removal, because the phosphate ions had less distance to reach the internal pores of the immobilized ZM beads. Chemical and electrochemical regeneration techniques were compared. Phosphates adsorbed on the ZM beads were effectively desorbed with NaCl, NaOH, and Na₂SO₄ solutions. An electrochemical regeneration system consisting of an anion exchange membrane between two platinum-coated titanium electrodes was successfully used to desorb and regenerate the phosphate-saturated ZM beads. Complete regeneration was reached under optimal experimental conditions. Chemical and electrochemical regeneration proved the reusability of the bead form of the entrapped ZM, and will enhance the economical performance of the phosphate treatment process.     

Effects of pressure and temperature on dyeing acrylic fibres with basic dyes in supercritical carbon dioxide

The dyeing of acrylic fibre with CI Basic Blue 47 has been investigated using an ammonium carboxylate perfluoropolyether as an auxiliary in order to perform the reverse micellar system in supercritical carbon dioxide media. The basic dye was satisfactorily solubilised in the interior of the reverse micelle in the system, and dyeability in the supercritical carbon dioxide media was excellent, even in the absence of a retardant and/or an acid. The optimum proton-rich condition for dyeing of acrylic fabric is performed in reverse micelle aggregates and the proton-rich water pool is suitable for dye uptake by the fibre even without the presence of additives. Changes in glass transition temperature of acrylic fibre in the carbon dioxide media also influence the dyeing behaviour of acrylic fabric.     

The influence of filler on the emission properties and rheology of carbon nanotube paste

CNT paste consists of organic solution, inorganic binder and filler. Organic solution contains organic resins and solvent including surfactants which finely disperse CNTs. Filler affects surface morphology, electron emission property, viscosity, and rheological characteristics of CNT paste. We used different fillers such as silver and alumina in CNT paste for special function. The emission properties of CNT paste with silver are similar to those of CNT paste with alumina if filler portion is the same. From the scanning electron microscope (SEM) different morphologies of CNTs was observed depending on the type of filler. CNT paste which showed good emission property had vertically well-aligned CNTs on the surface after surface treatment using adhesive tape. We measured viscosity and rheological properties with rheometer RS600 from HAAKE. Emission property of CNT paste was evaluated in vacuum chamber of 10^{− 6} Torr with pulse generator and duty was 1/500.     

Thermal and chemical desulfurization of low sulfur coals

This paper describes desulfurization characteristics of low sulfur coals prior to combustion and optimum conditions of three different desulfurization processes. These processes include two thermal treatment processes (mild pyrolysis and air oxidation) and an H₂O₂ leaching process. Dual processes composed of thermal and leaching processes were also evaluated. Low sulfur coals employed were two imported bituminous coals and two domestic anthracite coals. The optimum reaction temperatures and times of the thermal processes were 500–550 °C and 15–20 minutes, respectively. The optimum condition for the leaching process was obtained when the experiment carried out for 60 min at 90 °C using 30% H₂O₂. The dual process showed the best sulfur removal efficiency as expected among the evaluated processes. This paper is dedicated to Professor Hyun-Ku Rhee on the occasion of his retirement from Seoul National University.     

Thickness and composition dependence of the glass transition temperature in thin random copolymer films

Glass transition temperatures (T_g) of thin poly(styrene-co-methyl methacrylate) and poly(2-vinyl pyridine-co-styrene) films coated on a native oxide surface of Si wafer (100) were measured by ellipsometry. The thickness dependence of T_g can be properly fitted by previously suggested equation developed for homopolymers, based upon a continuous multi-layer model, although one component in thin random copolymer films demonstrates a slightly favorable interaction between a substrate and thin film, and another demonstrates a strongly favorable interaction. Surface and interface have a strong influence on T_g of thin film coated on substrate: the surface has the effect of reducing T_g, whereas the interface increases the T_g according to the degree of interaction between a substrate and thin film. This degree of interaction can be quantified as an interaction parameter (k), and is dependent on the composition of random copolymers. For the estimation of k values of thin random copolymer films, we proposed a parallel type additive function (1/k_ran=w₁/k₁+w₂/k₂) where w is a weight fraction of component.     

Physical properties of ethylene vinyl acetate copolymer (EVA)/natural rubber (NR) blend based foam

In this study an attempt was made to improve the rebound resilience and to decrease the density of ethylene‐vinyl acetate copolymer (EVA) foam. For this purpose, EVA was blended with natural rubber (NR), and EVA/NR blends were foamed at 155°C, 160°C, and 165°C. To investigate the correlation between crosslinking behavior and physical properties of foams, crosslinking behavior of EVA/NR blends was monitored. The physical properties of the foams were then measured as a function of foaming temperatures and blend compositions: 165°C was found to be the optimal temperature for a crosslinking of EVA/NR foam. As a result, the density of EVA/NR blend foamed at 165°C was found to be the lowest. EVA/NR (90/10) blend, foamed at 165°C, showed lower density, better rebound resilience, and greater tear strength than EVA foam. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 2212–2216, 2004     

Dietary Monounsaturated Fatty Acids but not Saturated Fatty Acids Preserve the Insulin Signaling Pathway via IRS-1/PI3K in Rat Skeletal Muscle

Saturated fatty acids (SFA) and monounsaturated fatty acids (MUFA) show different effects on the development of insulin resistance. In this study, we compared the effect of dietary SFA and MUFA on the insulin signaling pathway in the skeletal muscle of a type 2 diabetic animal model. Twenty-nine-week-old male Otsuka Long-Evans Tokushima fatty (OLETF) rats were randomly divided into three groups and fed one of the following diets for 3 weeks; a normal chow diet, an SFA (lard oil) enriched or a MUFA (olive oil) enriched high-fat diet. The vastus lateralis muscle was used for analyses. Insulin tolerance test showed improved insulin sensitivity in rats fed the MUFA diet, as compared to those fed the SFA diet (p < 0.001). The SFA diet reduced IRS-1 expression and phosphorylated PI3K levels in skeletal muscle, as compared with a chow diet (p < 0.001, respectively). On the contrary, muscle IRS-2 expression and phosphorylated ERK1/2 was significantly increased in rats fed the SFA diet (p < 0.001, respectively). Membrane translocation of glucose transporter type 4 decreased in the skeletal muscle of rats fed the SFA diet, as compared to those fed a chow diet (p < 0.001). These changes in insulin signaling pathway in skeletal muscle were not observed in rats fed the MUFA diet. In conclusion, the beneficial effect of dietary MUFA on insulin sensitivity is associated with a conserved IRS-1/PI3K insulin signaling pathway which was altered by dietary SFA.     

Formation and characterization of polyethylene blends for autoclave‐based expanded‐bead foams

Blends of linear‐low‐density polyethylene (LLDPE), low‐density polyethylene (LDPE), and high‐ density polyethylene (HDPE) were foamed and characterized in this research. The goal was to generate clear dual peaks from the expanded polyethylene (EPE) foam beads made from these blends in autoclave processing. Three blends were prepared in a twin‐screw mixing extruder at two rotational speeds of 5 and 50 rpm: Blend1 (LLDPE with 20 wt% HDPE), Blend 2 (LLDPE with 20 wt% LDPE), and Blend 3 (LLDPE with 10 wt% HDPE and 10 wt% LDPE). The differential scanning calorimetric (DSC) measurement was taken at two cooling rates: 5 and 50°C/min. Although no dual peaks were present, the results showed that blending with HDPE has a more noticeable effect on the DSC curve of LLDPE than blending with LDPE. Also, the rotational speed and cooling rate affected the shape of the DSC curves and the percentage area below the onset point. The DSC characterization of the batch foamed blends revealed multiple peaks at certain temperatures, which may be mainly due to the annealing effect during the gas saturation process. POLYM. ENG. SCI., 2010. © 2009 Society of Plastics Engineers