Primary dependence of 7-aryl-2,5-di-t-butyl-1,3,5-cycloheptatriene valence tautomerism on the π-acceptor strength of the 7-aryl substituent

¹³C NMR studies showed that the population of the norcaradiene form of the title systems containing p-CH₃O, H, and p-CF₃ on the 7-aryl group increases in this order. The result is consistent with the prediction from the π-acceptor strength of the aryl group estimated by INDO calculations.     

Effect of Ru crystal orientation on the adhesion characteristics of Cu for ultra-large scale integration interconnects

The adhesion of Cu on Ru substrates with different crystal orientations was evaluated. The crystal orientation of sputter deposited Ru could be changed from (1 0 0) to (0 0 1) by annealing at 650 °C for 20 min. The adhesion of Cu was evaluated by the degree of Cu agglomeration on Ru. Cu films on annealed Ru films with the (0 0 1) crystal orientation showed 28% lower RMS values and 50% lower Ru surface coverage than Cu as-deposited on Ru having the (1 0 0) crystal orientation after annealing at 550 °C for 30 min, which suggest that Cu wettability on the Ru(0 0 1) was better than that on the Ru(1 0 0) plane. The low lattice misfit of 4% between Cu(1 1 1) and Ru(0 0 1) may be the reason for this good adhesion property.     

Evaluation of fine structure of tubular zeolite NaA membrane by FTIR-ATR and FIB-TEM.

A zeolite NaA (LTA) membrane supported by an alumina porous support tube for pervaporation (PV) dehydration of ethanol was characterized by transmission electron microscopy (TEM) using a focused ion beam (FIB) thin-layer specimen preparation technique and by Fourier transform infrared attenuated total reflectance method (FTIR-ATR) using a diamond prism as the waveguide. FIB-TEM clearly presented cross-section images up to about 15 microm depth from the membrane surface. FTIR-ATR monitored the Si-O asymmetric stretching vibration spectrum. The Si-O spectrum was compared with the TEM image and their relationships were discussed. By combining the two methods, we could study the thickness of surface LTA crystals, the grain boundary, the LTA/alumina interface structure and the crystallinity and density of materials inside of the alumina porous support. Consequently, fine structure changes of the LTA membrane corresponding to the hydrothermal synthesis condition could be sensitively detected.     

Properties of holomorphic Wiener functions —skeleton,contraction, and local Taylor expansion

Summary We show that each holomorphic Wiener function has a skeleton which is intrinsic from several viewpoints. In particular, we study the topological aspects of the skeletons by using the local Taylor expansion for holomorphic Wiener functions.Supported in part by the Grant-in-Aid for Science Research 03740120 Min. Education     

Calculation of heat transfer and uniformity of chemical amplification during post-exposure bake

Heat transfer in a resist-coated silicon wafer using a bake process is theoretically evaluated by modeling the three-dimensional diffusion process, focusing on the controllability of the lithographic performance of chemically amplified resists. Six models of various ambient conditions are used. The proximity gap between the hotplate and the wafer is found to have a dominant influence on the heat transfer process for the whole system. Because the atmosphere near the wafer acts as a thermal diffusion buffer layer, no temperature gradient occurs in the resist, even when it is subjected to convective heat transfer from the resist surface. Experimental results obtained by X-ray lithography confirm the calculation results.     

Crosslinked poly(N-isopropylacrylamide) gel for electrophoretic separation and recovery of substances

Crosslinked poly(N-isopropylacrylamide) gel was tested on the feasibility for a preparative electrophoretic matrix. Horse heart myoglobin and bovine hemoglobin were well separated on the gel matrix electrophoretically by molecular sieving effect of the gel network. Relative mobilities of those proteins in the gel were larger than those in a crosslinked polyacrylamide gel of the same polymer concentration. After the separation, the protein-containing portion of the gel underwent swelling at 4°C and deswelling at 37°C, alternatively. As a result of the deswelling, each protein was recovered in a discharged solution out of the gel at almost 100% yield.     

A two step algorithm for solving a large scale semi-definite logit model

This paper proposes a two step algorithm for solving a large scale semi-definite logit model, which is appreciated as a powerful model in failure discriminant analysis. This problem has been successfully solved by a cutting plane (outer approximation) algorithm. However, it requires much more computation time than the corresponding linear logit model. A two step algorithm to be proposed in this paper is intended to reduce the amount of computation time by eliminating a certain portion of the data based on the information obtained by solving an associated linear logit model. It will be shown that this algorithm can generate a solution with almost the same quality as the solution obtained by solving the original large scale semi-definite model within a fraction of computation time.     

Aharonov–Bohm oscillations observed in nanoscale open-dot structures fabricated in an InAs surface inversion layer

We fabricated nanoscale open-dot structures in an InAs surface inversion layer using an atomic-force-microscope oxidation process. Due to its superior nanofabrication capability, small open-dot structures with the feature size ranging between 100 and 300 nm were successfully fabricated. The magnetoresistance signal measured at 4.2 K showed reproducible fluctuations and a periodic oscillation component that varies in both amplitude and periodicity depending on the dot size. We show that the period of the oscillations corresponds to that of the Aharonov–Bohm effect and propose that the possible mechanism for the oscillations is due to the formation of a one-dimensional electron channel enclosing the open-dot structure as a result of the electron transfer from the InAs oxide to InAs.