Novel Highly Acidic Nanoporous Cage Type Materials and Their Catalysis

Acylation of aromatic compounds such as veratrole (1,2-dimethoxybenzene), anisole, isobutyl benzene, and 2-methoxynaphthalene with acetic anhydride (Ac₂O) has been investigated over different solid acid catalysts such as MWW, BEA, FAU, MOR, and MFI. MWW catalysts have been characterized by X-ray diffraction, N₂ adsorption–desorption isotherm, and HR-FESEM characterization techniques. The reaction is studied in the temperature range 313–353 K under N₂ atmosphere. Among the catalysts tested, MWW was found to be more active than other zeolites. This is mainly due to its three dimensional porous structure with excellent textural characteristics. The effect of veratrole/Ac₂O molar ratio, catalyst concentration, and reaction temperature has been optimized to get higher conversion of Ac₂O. Under the optimized reaction conditions, MWW gave the Ac₂O conversion of 64.3% with a selectivity to acetoveratrone (3′,4′-dimethoxyacetophenone) (100%). It was also found that the structural features and acidity play an important role in the conversion and product distribution in the acylation of different aromatic substrates like anisole, isobutyl benzene, and 2-methoxy naphthalene. MWW catalyst has been reused in few cycles after regeneration by washing with ethyl acetate followed by calcination at 500 °C for 4 h without loss in its activity. The reaction kinetics of the catalyst was also studied and the results are discussed in detail.     

Wet releasing and stripping SU-8 structures with a nanoscale sacrificial layer

This paper presents a new method of wet releasing SU-8 structures using very thin Omnicoat^™ as sacrificial layer and NMD-3 developer as releasing solution. Four-inch sized SU-8 structures with different pattern and thickness of 65 μm have been successfully released from silicon substrate by this method. Experiments show that Omnicoat^™ layer is very helpful to strip SU-8 molds in which metal structures are electroplated. SU-8 can be removed directly using remover if there is an Omnicoat^™ layer between the substrate and SU-8 and the electroplated structures is with large dimension. In the case of electroplated structures with small feature size, SU-8 can be removed by combining wet stripping and plasma etching. Nickel micro coils with linewidth of 10 μm and aspect ratio of 4.1 have been fabricated. The analysis about the influence of Omnicoat^™ layer’s thickness on integrity of SU-8 micro coils is also given in our work.     

Muon kinetics in heat treated Al (–Mg)(–Si) alloys

Al–Mg–Si alloys are heat-treatable and rely on precipitation hardening for their mechanical strength. We have employed the technique of muon spin relaxation to further our understanding of the complex precipitation sequence in this system. The muon trapping kinetics in a material reveals a presence of atom-sized defects, such as solute atoms (Mg and Si) and vacancies. By comparing the muon kinetics in pure Al, Al–Mg, Al–Si and Al–Mg–Si when held at different temperatures, we establish an interpretation of muon trapping peaks based on different types of defects. Al–Mg–Si samples have a unique muon trapping peak at temperatures around 200 K. This peak is highest for samples that have been annealed at 70–150 °C, which have microstructures dominated by a high density of clusters/Guinier–Preston zones. The muon trapping is explained by the presence in vacancies inside these structures. The vacancies disappear from the material when the clusters transform into more developed precipitates during aging.     

Effect of Difference in Acceleration and Velocity Change on Product Damage Due to Repetitive Shock

To investigate the influence of different combinations of peak acceleration and velocity change on repetitive‐shock‐induced damages leading to cumulative fatigue in products, we performed drop tests of products packaged similar to those in actual transportation, from several different drop heights and with two kinds of cushioning materials. The damage boundary curves (DBCs), corresponding to the degree of damage per shock, were prepared to investigate the possibility of DBC application for the evaluation of repetitive‐shock‐induced damage. The drop test showed erroneous results, when predicting repetitive‐shock‐induced damage, if based only on the relationship between peak acceleration and the degree of damage per shock, as have been carried out in previously reported studies. In our study, the DBCs for a specific degree of damage per shock were prepared, although the ranges of the peak acceleration and velocity change were limited. Preparation of DBC corresponding to the degree of damage per shock, as determined from the peak acceleration and velocity change beforehand, may increase the accuracy of predicting repetitive‐shock‐induced damage to products from cumulative fatigue. Copyright © 2013 John Wiley & Sons, Ltd.     

Thermal conductivity and electrical resistivity of the T′ phase and the T phase in 2-1-4 oxide superconductors

The temperature dependences of the thermal conductivity,(T), and the electrical resistivity,(T), of sintered samples of Nd_1.85Ce_0.15CuO_4–y (NCCO) and Pr_1.85Ce_0.15CuO_4–y (PCCO) with the T phase, and La_1.85Sr_0.15CuO_4–y (LSCO) and La_1.935Ca_0.065CuO_4–y (LCCO) with the T phase, have been measured. The superconducting transition temperatureT _con , of NCCO, PCCO, LSCO, and LCCO were 26.4, 23.0, 37.1, and 8.8 K, respectively. The enhancement of(T) below justT _con such as seen in 1-2-3 oxide superconductors was not clearly observed.(T) for the samples of NCCO and PCCO showed a pronounced maximum such as that of sapphire crystal around 30 and 40 K, respectively. For these samples of NCCO and PCCO, it has been shown that the analysis based on the various phonon scattering mechanisms is in good agreement with our experiment.     

Machinability of BN free-machining steel in turning

In the past few years, extensive researches have been done to improve the machinability of work materials in order to increase productivity and reduce the effect on the environment. To satisfy these demands, various free-machining steels have been researched and developed. One of them is BN free-machining steel that contains hexagonal boron nitride (h-BN). However, the machinability was not stable. In this study, machining tests were carried out to clarify the machinability of steels and appropriate chemical composition of work material and tool material to achieve high efficient machining. Tested work materials were plane carbon steel JIS S45C and BN free-machining steels. The JIS S45C was used as the standard. The tool wear in turning BN free-machining steel was smaller than that in turning standard steel. In case of turning BN1 with P30 at 200, 300 m/min, the wear progress rate of flank wear and crater depth were about half as much as that in turning standard steel. BN free-machining steel showed slightly lower cutting temperature and smaller cutting force in comparison with standard steel at the tested cutting speeds. Al and N were detected as a layer at the tool wear region of P grade carbide tools after turning BN free-machining steel at high cutting speed. It is thought that one of the main reasons of outstanding machinability of BN free-machining steel is that the deposited layer containing Al and N acts as diffusion barrier at the tool–chip interface. In turning larger Al content BN-added steel with higher Ti content cutting tools, a larger wear reduction was observed. Therefore, it is said that not only added BN but also appropriate Al is necessary in work material.     

Lanthanum Chromite-Based Interconnects as Key Materials for SOFC Stack Development

The historical investigations on the physicochemical and transport properties of lanthanum chromite-based perovskite oxides are reviewed to evaluate the compatibility as interconnects in solid oxide fuel cells. These materials improve sinterability in air. This has led to investigations on other physicochemical properties of these materials, such as thermal expansion, mechanical strength, and chemical stability. Lanthanum and chromium ion can be substituted by alkaline earths or transition metals, and this translates into a large flexibility in physicochemical properties. However, the formation of oxygen vacancies in a reducing atmosphere can result in an undesirable isothermal expansion or oxygen permeation. The chemical stability of these materials is governed by the fast cation diffusion at the grain boundary of the polycrystals.     

An electrochemical study of poly(2,2′-dithiodianiline) in acidic aqueous media

Poly(2,2′-dithiodianiline) [poly(DTDA)], which is a conducting polymer interconnected with disulfide (SS) bonds, was studied electrochemically in acidic aqueous media. Redox reactions and structural changes of the poly(DTDA) in acidic aqueous solutions at various applied potentials and pH values were investigated. A Pourbaix diagram [potential (E)-pH profile] for the poly(DTDA) was plotted in order to distinguish the structures of the poly(DTDA) for the applied potentials and the pH values. The detailed structural changes were characterized using in situ UV-vis and surface-enhanced Raman spectroscopies.     

Discontinuous crack model for piezoelectric materials and its application to CED evaluation

In order to study the influence of electric displacement saturation on fracture behavior of a piezoelectric material, the electric displacement strip-saturation model by [Gao H, Zhang TY, Tong P. Local and global energy release rates for an electrically yielded crack in a piezoelectric ceramic. J Mech Phys Solids 1997;45:491-510] has been applied. However, this model is only applicable to problems such as that of a crack in an infinite plate for which it provides a singular solution. In order to overcome this situation, we developed a crack model for a piezoelectric material named discontinuous crack model that is presented in this paper, to evaluate crack energy density (CED) considering electric yielding and we studied its applicability through finite element analyses. The model is defined and methods to establish its constitutive equation are discussed. Moreover, it is shown that the model by Gao et al. and the ordinary crack model in continuum can be regarded as special cases of the discontinuous crack model. Subsequently, the CED and its derivatives for the discontinuous crack model are defined and their path independent expressions are also derived based on conservation laws. Finally, a finite element formulation is devised and the applicability of the model to the evaluations of CED and its derivatives is studied through finite element analyses of an example.     

Network centric approach to protection,control, and monitoring for power system

Due to the explosion in use of the Internet, it is expected that a variety of services will be provided through the communication network in the near future. Protection and control systems using the latest communication and information technology also allow for innovative solution to a wide range of power system problems. This paper describes a network‐centric approach to protection, control, and monitoring systems. When the proposed “Network” devices, server, and browser can communicate with each other, they can share information which can enhance the overall protection and control of the power systems. The paper includes: overview of network devices, key technologies, protection and control applications, issues, and conclusion. © 2004 Wiley Periodicals, Inc. Electr Eng Jpn, 149(4): 31–41, 2004; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20006