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.     

Cloning and functional characterization of the SUR2/SYR2 gene encoding sphinganine hydroxylase in Pichia ciferrii

Saccharomyces cerevisiae sphinganine C4-hydroxylase encoded by the SUR2 gene catalyses the conversion of sphinganine to phytosphingosine. We isolated the SUR2 gene from Pichia ciferrii using nucleotide sequence homology to S. cerevisiae SUR2 to study hydroxylation of sphinganine in the sphingoid base overproducing yeast P. ciferrii. A positive clone was confirmed by nucleotide sequencing. A syringomycin-E resistance phenotype of a S. cerevisiae sur2-null mutant was complemented by expression of the cloned P. ciferrii SUR2 gene. Restoration of phytosphingosine production in the complemented strain was also confirmed, indicating that the cloned gene is a functional homologue of S. cerevisiae SUR2. .     

Investigation of the Reduction/Oxidation Behavior of Cobalt Supported on Nano-ceria

The oxidation and reduction behavior of cobalt catalysts supported on nano-ceria (5–8 nm) was investigated under hydrogen, oxygen and water atmospheres. A novel quantitative isothermal reduction (QIR) technique was introduced to analyze the kinetics and activation barrier of Co reduction. CoO to Co reduction was found to be of first order in the 250–350 °C temperature range. Temperature programmed reduction and oxidation experiments were conducted and the Kissinger method was used to obtain apparent activation energies for reduction and oxidation with O₂. The apparent activation energy for CoO reduction was found to agree with that obtained from the QIR technique. Re-oxidation of Co metal was found to have a slightly lower activation energy barrier than the reduction. The reduction and oxidation behavior was further investigated with in situ XANES where the reaction order for reduction was observed to change at 450 °C. The pre-reduced samples were seen to re-oxidize under a water atmosphere, where the oxidation followed first order kinetics. Re-oxidation by water yielded a higher activation energy when compared to re-oxidation under oxygen.     

Study on the possibility of waste mushroom medium as a biomass resource for biorefinery

In order to investigate the possibility of waste mushroom medium as a biomass resource for biorefinery, characteristics of hydrolysate and pretreated biomass obtained from oxalic acid pretreatment were examined. The hydrolysate contained high glucose and low concentrations of inhibitors. The glucose concentration in the hydrolysate particularly increased when temperature gradient was used during pretreatment, compared with that of isocratic condition. The highest increase rate of glucose was 63.16% when pretreatment was performed at 140 °C for 25 min with 0.032 oxalic acid (g/g), and increased temperature to 170 °C. At the same time, ethanol production of Scheffersomyces stipitis using hydrolysate was 15.72 g/L after 48 h, which correspond to an ethanol volumetric productivity of 0.33 g L^?1 h^?1. Most of the lignin and some of the cellulose remained in the pretreated biomass. The total lignin content of the pretreated biomass, represent between 31.81 and 45.05%, compared to 28.8% of the raw material. The calorific value of the pretreated biomass ranged from 4940 to 5111 kcal/kg which represent increase of 3–6% compared to the raw material, due to higher contents of lignin in the pretreated biomass.     

Synthesis and luminescence properties of new blue‐light‐emitting polyconjugated poly{1,1′‐biphenyl‐4,4′‐diyl‐[1‐(4‐t‐butylphenyl)]vinylene} polymers and copolymers

Three new soluble polyconjugated polymers, all of which emitted blue light in photoluminescence and electroluminescence, were synthesized, and their luminescence properties were studied. The polymers were poly{1,1′‐biphenyl‐4,4′‐diyl‐[1‐(4‐t‐butylphenyl)]vinylene}, poly((9,9‐dioctylfluorene‐2,7‐diyl)‐alt‐{1,4‐phenylene‐[1‐(4‐t‐butylphenyl)vinylene‐1,4‐phenylene]}) [P(DOF‐PVP)], and poly([N‐(2‐ethyl) hexylcarbazole‐3,6‐diyl]‐alt‐{1,4‐phenylene‐[1‐(4‐t‐butylphenyl)]vinylene‐1,4‐phenylene}). The last two polymers had alternating sequences of the two structural units. Among the three polymers, P(DOF‐PVP) performed best in the light‐emitting diode devices of indium–tin oxide/poly(ethylenedioxythiophene) doped with poly(styrene sulfonate) (30 nm)/polymer (150 nm)/Li:Al (100 nm). This might have been correlated with the balance in and magnitude of the mobility of the charge carriers, that is, positive holes and electrons, and also the electronic structure, that is, highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) levels, of the polymers. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 307–317, 2006     

DEA based multi-period evaluation system for research in academia

Various types of incentive systems are widely used by many companies and organizations for better performances. However, despite the demand for the fair incentive systems, those systems in academia have not been well established and fairly operated. Using an example of a professor evaluation system, we examine two main problems of the existing incentive systems in academia – ignoring the input aspect and focusing only on the short-term performance. By applying the super-efficiency DEA and considering multi-period output, we show that the input factors and the time trend of outcomes need to be incorporated for the fair evaluation of professors and their research performance.     

Radiation-induced synthesis of solid alkaline exchange membranes with quaternized 1,4-diazabicyclo[2,2,2] octane pendant groups for fuel cell application

In this study, anion exchange membranes having various quaternary ammonium groups were prepared by using a radiation-induced graft polymerization method and followed by subsequent treatment of films with amines. FT-IR and SEM-EDX techniques were employed to monitor the reaction progress. The cross-sectional distribution of the anionic exchange functional groups through the membranes has also been investigated using SEM-EDX technique. The results reveal that the anion exchange groups were found to be evenly distributed throughout the membranes. It was also observed that the physico-chemical properties of the anion exchange membranes such as water uptake, ionic conductivity, thermal stability, chemical stability, mechanical properties, and dimensional stability are largely influenced by the chemical structure of the quaternary ammonium moiety which is attached to the graft chains. Among the prepared anion exchange membranes, the membrane having mono-quaternized 1,4-diazabicyclo[2,2,2]octane moiety was found to have both enhanced chemical and dimensional stabilities, while the others having quaternized trimethylamine or bis-quaternized 1,4-diazabicyclo[2,2,2]octane have the decreased dimensional and chemical stabilities.     

Influence of the duty cycle on structural and mechanical properties of oxide layers on Al-1050 by a plasma electrolytic oxidation process

Oxide layers were prepared on Al-1050 substrates by an environmentally friendly plasma electrolytic oxidation process using an alkaline solution of Na₂SiO₃ (8 g/L) and NaOH (3 g/L) as the electrolyte. The effects of three different duty cycles (20%, 40%, and 60%) on the structure and hardness of the oxides were investigated. XRD analysis revealed that the oxides were mainly composed of α-Al₂O₃, γ-Al₂O₃, and mullite. The proportion of each phase depended on various electrical parameters, such as the duty cycle and frequency. The morphology, thickness, and the elemental distribution of the oxides were examined by scanning electron microscopy and energy dispersive spectroscopy. The thicknesses of the oxides were found to vary from 20 μm to more than 60 μm for various duty cycles, when identical treatment durations were used. The oxidation treatment also resulted in good adhesion between the oxide layer and the substrate. SEM images indicated that the oxide layers formed at the 60% duty cycle exhibited relatively coarser surfaces with larger pore sizes and sintering particles, and slower growth rates than did those formed at the 20% duty cycle, under identical treatment durations. The oxides prepared at the 20% duty cycle showed smooth surfaces. The oxides layers were found to improve the micro-hardness of Al-1050. In particular, the oxide layers formed at the 40% duty cycle exhibited relatively better micro-hardness owing to their compact microstructures.