Improved estimation of the resistivity of pure copper and electrical determination of thin copper film dimensions

Improved values for the resistivity, ρ, of pure, bulk copper from 50 to 1200 K, and their confidence intervals, are developed by extending the analysis of Matula. A recommended value for dρ/dT and its confidence interval in the temperature range of 290–425 K is developed for use with Matthiessen's rule to calculate the electrical thickness of thin copper films and the cross-sectional area of copper lines from resistance measurements at two temperatures. Error analyses are used to estimate the uncertainty with which the electrical thickness and cross-sectional area can be determined. Values for the temperature coefficient of resistance of pure, bulk copper are also provided.     

The role of native grammars in correcting errors in second language learning

This paper describes VP², a system that has been implemented to tutor nonnative speakers in English. This system differs from many tutoring systems by employing an explicit grammar of its user's native language. This grammar enables VP² to customize its responses by addressing problems due to interference of the native language. The system focuses on the acquisition of English verb-particle and verb-prepositional phrase constructions. Its correction strategy is based upon comparison of the native language grammar with an English grammar. VP² is a modular system: its grammar of a user's native language can easily be replaced by a grammar of another language. The problems and solutions presented in this paper are related to the more general question of how modelling previous knowledge facilitates instruction in a new skill.     

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Electromagnetic simulation of bonding wires and comparison withwide band measurements

Several typical bonding wire configurations have been measured in a frequency range up to 20 GHz using a vector network analyzer. Based on scanning electron microscope (SEM) pictures all bonding wires have been discretized and orthogonal grids suitable for electromagnetic simulation have been generated. Full wave finite difference time domain (FDTD) simulations as well as static and quasi static inductance extraction using a new Monte Carlo technique and FastHenry as well as capacitance extraction with a finite element method have been carried out. Numerical results are compared to measured scattering parameters and their quality and frequency dependence is discussed. All simulation techniques are evaluated with respect to their computational effort     

An interconnected 2D-TM EBG structure for millimeter and submillimeter waves

Due to their unique properties, electromagnetic bandgap (EBG) materials are of high interest for applications in communication technology for many frequency bands from microwave up to optical frequencies. We have investigated in both simulation and experiment a two dimensionally periodic EBG structure made by reactive ion etching of silicon with a bandgap for transverse magnetic waves in the millimeter wave range around 100 GHz. The structure comprises both a large bandgap and a high mechanical stability due to interconnecting dielectric bridges.     

Model processing agents for rubber manufacturing

Summary Oligomers with different aromatic substituents (oligostyrenes, oligo-p-ethylstyrenes, oligo-p-methoxystyrenes and oligo-1-vinylnaphthalenes) were synthesized by living anionic polymerization using sec-butyllithium as initiator. Number average degrees of polymerization were varied between 2 and 16 and narrow homologuedistributions were obtained. In the case of the benzenic types the isolation into pure homologues from dimers to hexamers was carried out by preparative gel permeation chromatography (GPC). In a polymeranalogous heterogeneous catalytic hydrogenation reaction the aromatic compounds were converted into oligomers with saturated cyclic structures, the initial homologue-distributions not being changed. Characterization of all oligomers was performed by GPC and proton nuclear magnetic resonance (¹H-NMR). In the case of oligostyrenes and oligo-p-ethylstyrenes the occurrence of the characteristic high field shift of the ortho-protons is observed in dependence of the degree of polymerization. Oligo-1-vinylnaphthalenes show three differently shielded aromatic resonance areas.     

Transfer of rps19 to the nucleus involves the gain of an RNP-binding motif which may functionally replace RPS13 in Arabidopsis mitochondria

The discovery of disrupted rps19 genes in Arabidopsis mitochondria prompted speculation about the transfer to the nuclear compartment. We here describe the functional gene transfer of rps19 into the nucleus of Arabidopsis. Molecular cloning and sequence analysis of rps19 show that the nuclear gene encodes a long N-terminal extension. Import studies of the precursor protein indicate that only a small part of this extension is cleaved off during import. The larger part of the extension, which shows high similarity to conserved RNA-binding domains of the RNP-CS type, became part of the S19 protein. In the Escherichia coli ribosome S19 forms an RNA-binding complex as heterodimer with S13. By using immuno-analysis and import studies we show that a eubacterial-like S13 protein is absent from Arabidopsis mitochondria, and is not substituted by either a chloroplastic or a cytosolic homologue of this ribosomal protein. We therefore propose that either a highly diverged or missing RPS13 has been functionally replaced by an RNP domain that most likely derived from a glycine-rich RNA-binding protein. These results represent the first case of a functional replacement of a ribosomal protein by a common RNA-binding domain and offer a new view on the flexibility of biological systems in using well-adapted functional domains for different jobs.     

Corrosion of high temprature alloys in the primary circuit helium of high temperature gas cooled reactors. – Part I: Theoretical background

The interaction of Ni and Fe-Ni base alloys with the reactive impurities H₂O, CO, H₂ and CH₄ in simulated cooling gas of the primary circuit of the High Temperature Gas Cooled Reactor (HTGR) causes corrosion effects that can significantly influence the mechanical properties. Apart from the formation of surface scales (oxides, carbides or mixed oxides/carbides), structural changes of the alloys are observed; depending on gas composition, gas supply rate and test temperature, carburization or decarburization can occur. In this report it is shown that an interpretation of the basic corrosion effects is possible on the basis of a modified stability diagram for chromium provided that - the kinetics of elementary gas metal reactions are incorporated in the expressions for carbon activity and oxygen partial pressure of the atmosphere and - the gradients of the potentials across the surface scales are taken into account. The interpretation allows the derivation of the corrosion behaviour of NiCr-base alloys in different HTGR helium compositions and enables the limits for the formation of protective chromia surface scales to be given. The influence of alloying elements other than chromium can be explained qualitatively. The results can be transferred to other reactive gas mixtures, which are characterized by an oxygen partial pressure near to the dissociation pressure of the scale forming oxides.