Acidity of β zeolite with different Si/Al2 ratio as measured by temperature programmed desorption of ammonia

High quality β zeolite (BEA) with a Si/Al₂ ratio of 30:70 was readily prepared by a dry gel conversion method. Acidity of the thus prepared β zeolite was measured by an improved technique of temperature programmed desorption of ammonia. Concentration of acid site, measured from the desorbed ammonia, was nearly equal to that of aluminum in the zeolite, and the enthalpy change of ammonia desorption, i.e., the strength of acidity, was 124–127 kJ mol⁻¹, and independent of the concentration of acid site. The long tailing desorption of ammonia was distinct at higher temperature, and this was characteristic of BEA. The tail-like desorption spectrum may be correlated with the presence of strong acid site due to the defect or the tetrahedral site with different structural environments; the conclusion was supported by the characterization data using NMR, IR, and test reaction. Thus found solid acidity was compared with that of the commercially available β zeolite; the observed small difference was explained due to the presence of extra-framework Al.     

Telme: a personalized, context-aware communication support system

True global communication will require more than just language translation technologies. To fully understand each other, people also need context-specific information. The authors have developed Telme, a support system that gives users real-time information to help bridge the knowledge and experience gap. The authors explain the Telme framework for wearable computers connected to a central knowledge base server. The server controls a background knowledge database and downloads data on user request.     

Enabling situated knowledge management for complex instruments by real-time reconstruction of surface coordinate system on a mobile device

We have developed an approach to implementing a system for managing situated knowledge for complex instruments. Our aim is to develop a system that guides a user through the steps for operating complex scientific instruments. A user manual is often inadequate support for a community of users, so direct communication with an expert is often required. One reason for this is that not all of the author’s expert knowledge was included in the manual, thus limiting the contents to explicit knowledge. This is a main concern of modern knowledge management practitioners who are attempting to design systems that consider both explicit and tacit knowledge. The key is to distribute explicit knowledge through interaction with the real world so that users can develop tacit knowledge as well as acquire explicit knowledge. We describe technical difficulties related to referencing the real world, which is required for interaction, and describe a novel approach to building a low-cost three-dimensional pointer for obtaining the required knowledge, which constitutes our preliminary result.     

Si-film growth using liquid phase epitaxy method and its application to thin-film crystalline Si solar cell

We have developed a new apparatus for the growth of liquid-phase epitaxy (LPE)-Si films on 5 in Si wafers. We have obtained high growth rates of 0.1–1.0 μm/min and minority-carrier lifetime of average value of 10 μs over the whole of wafer, whereas the thickness uniformity was degraded when rotating the wafers in the solvent. We also demonstrated to growth of LPE-Si films on porous Si layers and to separate the Si films from the porous layers. A 9.5% cell was obtained using a LPE-Si film after separation.     

Effects of divalent metal ion (Mg, Zn and Be) doping on photocatalytic activity of ruthenium oxide-loaded gallium nitride for water splitting

The effects of divalent metal ion doping on the photocatalytic activity of GaN powder for overall water splitting were studied. The doping of Zn²⁺, Mg²⁺ and Be²⁺ to GaN converted it to be a remarkably active and stable photocatalyst in the presence of RuO₂ as a co-catalyst. Both H₂ and O₂ were produced from the initial stage of UV light illumination, and the ratio of H₂ to O₂ attained at the stoichiometric ratio of 2.0 at stationary conditions. Main absorption of undoped GaN was at around 390 nm, and a slight shift to longer wavelength occurred with the divalent metal ion-doped GaN. Undoped GaN showed photoluminescence peak due to band gap transition, whereas Zn²⁺ and Mg²⁺-doped GaN generated a broad photoluminescence peak having a center at around 450 nm and a tail extending to 600 nm. In RuO₂-dispersed Mg²⁺-doped GaN, with increasing content of Mg in starting materials used for preparation, the activity increased, whereas photoluminescence intensity decreased. The role of divalent metal ion dopants is concluded to produce p-type GaN, which is able to increase the concentration and mobility of holes.     

Designing conversational agents: effect of conversational form on our comprehension

We have developed a broadcasting agent system, public opinion channel (POC) caster, which generates understandable conversational form from text-based documents. The POC caster circulates the opinions of community members by using conversational form in a broadcasting system on the Internet. We evaluated its transformation rules in two experiments. In experiment 1, we examined our transformation rules for conversational form in relation to sentence length. Twenty-four participants listened to two types of sentence (long sentences and short sentences) with conversational form or with single speech. In experiment 2, we investigated the relationship between conversational form and the user’s knowledge level. Forty-two participants (21 with a high knowledge level and 21 with a low knowledge level) were selected for a knowledge task and listened to two kinds of sentence (sentences about a well-known topic or sentences about an unfamiliar topic). Our results indicate that the conversational form aided comprehension, especially for long sentences and when users had little knowledge about the topic. We explore possible explanations and implications of these results with regard to human cognition and text comprehension.     

Catalytic activity of PdO/ZrO2 catalyst for methane combustion

Catalytic activity of ZrO₂ supported PdO catalysts for methane combustion has been investigated in comparison with Al₂O₃ supported PdO catalysts. It was found that the drop of catalytic activity owing to decomposition of PdO at a high temperature region (600–900°C) was suppressed by using ZrO₂ support. Temperature-programmed reduction (TPR) measurements of the catalyst with hydrogen revealed that the PdO of PdO/Al₂O₃ catalyst was reduced at the temperature less than 100°C, whereas in PdO/ZrO₂ catalyst the consumption of hydrogen was also observed at 200–300°C. This result indicates that the stable PdO species were present in the PdO/ZrO₂ catalyst. In order to confirm the formation of the solid solution of PdO and ZrO₂, X-ray diffraction (XRD) analyses of the mixtures of ZrO₂ and PdO calcined at 700–900°C in air were carried out. The lattice volume of ZrO₂ in the mixture was larger than that of ZrO₂. Furthermore, the Pd thin film on ZrO₂ substrate was prepared as a model catalyst and the depth profile of the elements in the Pd thin film was measured by Auger electron spectroscopy (AES). It was confirmed that Zr and O as well as Pd were present in the Pd thin film heated at 900°C in air. It was considered that the PdO on ZrO₂ support might be stabilized by the formation of the solid solution of PdO and ZrO₂.     

Flame structure of wall-impinging diesel fuel sprays injected by group-hole nozzles

This paper describes an investigation of the flame structure of wall-impinging diesel sprays injected by group-hole nozzles in a constant-volume combustion vessel at experimental conditions typical of a diesel engine. The particular emphasis was on the effect of the included angle between two orifices (0-15 deg. in current study) on the flame structure and combustion characteristics under various simulated engine load conditions. The laser absorption scattering (LAS) technique was applied to analyze the spray and mixture properties. Direct flame imaging and OH chemiluminescence imaging were utilized to quantify the ignition delay, flame geometrical parameters, and OH chemiluminescence intensity. The images show that the asymmetric flame structure emerges in wall-impinging group-hole nozzle sprays as larger included angle and higher engine load conditions are applied, which is consistent with the spray shape observed by LAS. Compared to the base nozzle, group-hole nozzles with large included angles yield higher overall OH chemiluminescence intensity, wider flame area, and greater proportion of high OH intensity, implying the better fuel/air mixing and improved combustion characteristics. The advantages of group-hole nozzle are more pronounced under high load conditions. Based on the results, the feasibility of group-hole nozzle for practical direct injection diesel engines is also discussed. It is concluded that the asymmetric flame structure of a group-hole nozzle spray is favorable to reduce soot formation over wide engine loads. However, the hole configuration of the group-hole nozzle should be carefully considered so as to achieve proper air utilization in the combustion chamber. Stoichiometric diesel combustion is another promising application of group-hole nozzle.     

Effects of processing and cooking on the levels of pesticide residues in wheat samples

The effects of processing and cooking on the levels of pesticide residues in wheat samples were investigated for 13 pesticides in pre-harvest (Pre, 9 pesticides) and post-harvest (Post, 6 pesticides) samples. In the milling process, the transfer ratios (%, total pesticide residue amount in product/that in wheat grain) of wheat bran were greater than 70% and 80% for pre-harvest and post-harvest samples, respectively. The transfer ratios of flour ranged from 1.7% to 23% (Pre) and 4.0% to 11% (Post). There was no significant difference in transfer ratio among the pesticides investigated. The processing factors (Pf, the concentration (mg/kg) of pesticide in product/that in the wheat grain) of flour ranged from 0.030 to 0.40 (Pre) and 0.069 to 0.18 (Post). The values in pre-harvest samples were higher than those in post-harvest samples. Investigation of changes of pesticide residues during processing and/or cooking is useful not only to establish MRLs, but also to recognize actual levels of pesticide residues in food.