不同结构活性炭对甲苯的吸附性能

考察了不同结构的活性炭样品对高浓度和低浓度甲苯蒸汽的吸附行为,采用低温(77 K)氮气吸附和129Xe-核磁共振方法对所用活性炭的结构进行了表征.并将活性炭对甲苯的吸附性能与其结构进行了关联.结果表明孔容积大的活性炭对高浓度甲苯蒸汽吸附容量大,而具有丰富微孔和较小平均孔径的活性炭对低浓度(2×10-5)甲苯蒸汽具有高的吸附容量.沥青基活性炭纤维对低浓度(2×10-5)甲苯蒸汽表现出较好的吸附能力.随着比表面积的增大,活性炭纤维对低浓度(2×10-5)甲苯蒸汽的吸附容量略有增加.OG5A,OG10A,OG15A和OG20A在30 ℃下对2×10-5甲苯蒸汽的饱和吸附容量分别为202 mg/g,219 mg/g,221 mg/g和235 mg/g.     

Preparation of Polymer-stabilized Palladium–silver Bimetallic Nanoparticles by γ-irradiation and their Catalytic Properties for Hydrogenation of cis,cis-1,3-Cyclooctadiene

Polyvinypyrrolidone (PVP)-stabilized Pd-Ag bimetallic colloids were successfully prepared in an acetone:2-propanol solution mixture of palladium acetate and silver perchlorate, and in an aqueous solution of palladium nitrate and silver nitrate by γ-irradiation. The prepared PVP-stabilized bimetallic nanoparticles were characterized by UV, TEM, XRD, and XPS. In Pd–Ag bimetallic nanoparticles, the XPS data indicated that the constituent elements were in the metallic state, and the palladium atoms were concentrated on the surface of the alloy cluster. These PVP-stabilized bimetallic nanoparticles were used as catalysts for hydrogenation of cis,cis-1,3-cyclooctadiene (COD).     

Electrochemical properties of polyethylene membrane modified with sulfonic and phosphonic acid groups

Ion-exchange membranes modified with sulfonic (-SO₃H) and phosphonic acid (-PO₃H) groups were prepared by radiation-induced grafting of glycidyl methacrylate (GMA) onto polyethylene (PE) films and sub-sequent sulfonation and phosphonation of poly(GMA) graft chains. The surface area, thickness and volume of grafted PE film increased with increasing grafting yield. The specific electrical resistance of PE membrane modified with the -PO₃H and -SO₃H groups decreased with increasing the ion-exchange capacity. The PE membrane modified with -PO₃H group had a lower specific electrical resistance than that of PE membrane modified with -SO₃H group.     

Compositional analysis of deasphalted oils from Arabian crude and their hydrocracked products

The deasphalted oil (DAO) and its hydrocracked products were analyzed by gas chromatograph with an atomic emission detector (GC-AED), time-of-flight mass spectra (TOF-MS) and X-ray diffraction (XRD) to evaluate the product quality and reaction progress in addition to the yields of the products. Carbon GC-AED spectra revealed that carbon species distributions in distillate products were almost same regardless of their yields and reaction conditions. No sulfur species were found in gasoline and kerosene, while significant reduction of sulfur contents was found in gas oil (GO) according to the hydrocracking reaction temperature and liquid-volume hourly space velocity (LHSV). Vacuum gas oil (VGO) was also analyzed by GC, but it showed a large lump of low resolution. TOF-MS and XRD results indicated that the resid in the feed was cracked into smaller molecules in the product resid. These comprehensive analyses about feeds and products from various hydrocracking process could offer basic information for optimizing the process in industry.     

Activated carbon nanofiber produced from electrospun polyacrylonitrile nanofiber as a highly efficient formaldehyde adsorbent

Electrospun polyacrylonitrile (PAN)-based nanofiber with a uniform diameter of ca. 800 nm was carbonized and steam-activated to produce activated carbon nanofiber with tailored microporosity and abundant nitrogen-containing functional groups as highly efficient adsorption sites. A remarkable amount of formaldehyde, a typical indoor pollutant, was adsorbed onto the pore surface of the PAN-based activated carbon nanofibers even at a low concentration (ca. 11 ppm), demonstrating more than twice as long as breakthrough time of formaldehyde adsorption as compared to conventional activated carbon fibers of larger fiber diameter. The tailored shallow microporosity was considered to afford the preferential adsorption of formaldehyde also in a humid environment.     

Comparison of consumer perception and liking of <Emphasis Type="Italic">bulgogi</Emphasis> marinade sauces between Korea and Japan using flash profiling

This study compared the perception of and preference for seven bulgogi marinade sauces between Korean and Japanese consumers. Flash profiling (10 panelists each) and consumer test (97 Japanese and 102 Koreans) were conducted. Results showed that both Korean and Japanese panelists perceived the samples similarly but described using different terms. There were significant crosscultural differences in most liking and just-about-right attributes, except texture liking and sweetness. Both consumer panelists preferred sweeter samples, but Japanese consumers rated liking for less sweet samples higher than Korean consumers. Japanese consumers considered strong saltiness, umami, and soy sauce flavor as “just-about-right,” whereas Korean consumers considered the same levels as “much too strong”. Familiarity showed a significantly positive correlation with both Korean and Japanese consumers’ liking, but authenticity was only significantly correlated with Korean consumers’ liking. This indicates that perception of authenticity might not have a strong impact on Japanese consumers’ liking.     

Effect of Na-diffusion on the electrical properties of SrTiO3

Grain boundary characteristics of Na-diffused SrTiO₃ were investigated. It was observed that Na ions are segregated in grain boundaries by secondary ion mass spectroscopy analysis. Using I-V characteristics and C-V measurement, the non-linearity coefficient and the potential barrier height were found to be 15.6, 0.82 eV, respectively. The I-V characteristics, complex plane analysis, and dc voltage step technique were performed to study the electrical properties of a single grain boundary. From the results of complex plane analysis, the deep electronic level was varied from 0.10 to 0.31 eV, which can be explained by the substitution of Na ions for Sr ions.     

Effect of metal-sulfide additives on electrochemical properties of nano-sized Fe2O3-loaded carbon for Fe/air battery anodes

In the present study, K₂S and Bi₂S₃ were used as additives in electrolytes and electrodes, respectively. The effects of these additives on the electrochemical properties of nano-sized Fe₂O₃-loaded carbon electrodes were investigated using cyclic voltammetry (CV), galvanostatic cycling performance and scanning electron microscopy (SEM), along with electron dispersive spectroscopy (EDS). The results showed that both K₂S and Bi₂S₃ significantly reduced hydrogen evolution and benefited the Fe₂O₃-loaded carbon electrode, such as by retarding passivation and improving the discharge capacity. The effects of metal sulfide additives depended on the carbon used. For Bi₂S₃ additive, all carbons provided larger capacities than acetylene black (AB) while AB gave greater capacity than other carbons when K₂S was used.     

An Architecture for Service Quality Management Using Cooperative Communications

The rapid enhancement and explosive expansion of mobile communication systems will lead to an increased demand for multimedia services. Various multimedia contents will be available due to the proliferation of IPTV, video on demand, user-generated content, and content-centric networking. Therefore, multimedia service quality is becoming a critical issue. The static allocation of network resources may not be sufficient to guarantee the required service quality of multimedia in wireless networks. For ensuring the service quality, it is important to manage the resources considering the overall performance of the network and the end system. In particular, a certain level of service quality should be maintained regardless of the network situation. To achieve this objective, we first propose an architecture for service quality management and then present a detailed framework and mechanisms to maintain the desired service quality using the cooperation between communication entities in wireless networks. Simulation results are also presented to show that the proposed framework works well in wireless networks.     

Optimum content of Nafion ionomer for the fabrication of MEAs in PEMFCs with spray-coated Pt/CNT electrodes

To enhance the performance of a polymer electrolyte membrane fuel cell (PEMFC), a Pt catalyst was supported on carbon nanotubes (CNTs) and the optimum content of Nafion ionomer in the Pt/CNT electrode was examined by cell performance tests, cyclic voltammetry, and electrochemical impedance spectroscopy. The amount of the Pt catalyst supported on the CNTs was 34 wt.%. The Nafion content significantly changed the protonic and electronic conductivities as well as the mass transfer properties. As such, the performance of the cell was highly dependent on the content of Nafion ionomer. The results of the cell performance tests revealed that the optimum content of Nafion ionomer in the Pt/CNT electrode was about 20 wt.%.