Plasma chemistries for dry etching of NiFe and NiFeCo

Plasma chemistries based on chlorine, bromine, or iodine have been investigated for inductively coupled plasma etching of NiFe and NiFeCo. There is clear evidence of a chemically enhanced etch mechanism with both Cl₂- and I₂- based mixtures, with no enhancement present for Br₂ chemistries. Etch yields are typically low (≤0.25), emphasizing the need for high ion fluxes in order to achieve practical material removal rates.     

V.92: the last dial-up modem?

Ever since the first dial-up modems appeared in the 1960s, their obsolescence has been repeatedly predicted. However, contrary to such predictions, dial-up modems thrived in the 1980s and 1990s as a result of the slow rollout of residential digital services and the unprecedented growth of internet and remote access. Since the first 300 b/s dial-up modem standard (V.21), modem speeds have increased steadily. Most recently, International Telecommunications Union (ITU) Recommendation V.90 (1998) takes advantage of the direct digital-network connection of an internet service provider (ISP) remote-access server to achieve speeds of more than 50 kb/s downstream (from ISP to a user). However, for upstream transmission (from a user to ISP), V.90 employs the older V.34 modulation (1994), which typically delivers on the order of 30 kb/s. A new ITU modem standard called V.92 increases upstream rates to above 40 kb/s, again by taking advantage of pulse code modulation connections. In this paper, we present the transmission scheme that has been adopted for V.92. It involves a generalization of Tomlinson-Harashima precoding. We predict that V.92 will be the last dial-up modem standard. However, we have to wonder whether we might be falling into the same trap into which many others have fallen in the past. The future will be the judge!.     

Interfacial chemistry of humidity-induced adhesion loss of chlorinated rubber on rusted steel substrates

The effect of the exposure to the humidity of a chlorinated rubber coating applied to pre-rusted mild steel has been investigated from the interfacial chemistry and adhesion point of view. X-ray photoelectron spectroscopy (XPS) data suggest that the locus of failure changes with the time of exposure to the humidity. The adhesion strength values are strongly dependent on the time of exposure. The presence of a pre-rusted layer on the mild steel has a detrimental effect on the formation of bonds between the metallic substrate and the coating after the curing process. After 1 day of exposure, the adhesion values increase nearly twice compared to the non-exposed system. XPS data suggest the presence of an important coating residue on the interfacial substrate surface. The locus of adhesion loss is probably within the coating closest to the substrate. After 30–60 days of exposure, adhesion again shows low values, the locus of adhesion loss being now inside the transformed pre-corroded layer.     

The novel low temperature synthesis of nanocrystalline MgAl2O4 spinel using “gel” precursors

Nanocrystalline MgA1₂O₄ was synthesized by pyrolysis of the homogeneous spinel precursor, Mg(C₄H₅O₂)₂·(H₂O):Al₂(OH)₃(C₃H₃O₂)₃·(H₂O)₂:NH₄(C₃H₃O₂)·(H₂O). The spinel precursor gel is composed of a mixture of magnesium and aluminum acrylate salts dissolved in an ammonium acrylate gel. The reaction of acrylic acid with magnesium hydroxide in water produced magnesium methacrylate, and a similar reaction of basic aluminum acetate produced the aluminum salt of acrylic acid. The reaction of acrylic acid with ammonium hydroxide produced the ammonium acrylate gel. Ammonium acrylate gel was found to absorb many times its own weight of water. Although similar properties have been identified in PMMA and in the polymer of sodium acrylate, only the ammonium acrylate gel exists as an unpolymerized monomer. The spinel precursor gel is a pre-ceramic material that yields an amorphous oxide phase at 425°C that begins to crystallize to the MgAl₂O₄ spinel at 600°C and is fully crysta1line at 1030°C with a uniform particle size of 7-100 nm. The spinel precursor gel and the nanocrystalline MgA1₂O₄ spinel were characterized by XRD and TEM.     

Lyle Hicks Lanier (1903–1988).

Lyle H. Lanier was at the core an experimental psychologist who exerted influence on psychology at large by both his research and his administrative endeavors. Lanier passed away at his retirement home, in Phoenix, Arizona, on December 30, 1988. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Dispersion of bulk silica onto alumina to form a dispersed,surface phase oxide structure

Addition of colloidal silica to a porous alumina results in gelation onto the exterior surface of the alumina. Subsequent steam treatment with a high steam content allows silica to migrate into the pores of the alumina to form a surface phase oxide structure. The dispersed silica phase on alumina has low acidity in comparison to silica-alumina co-gels as measured by a standard gas oil cracking test. ESCA was useful to follow the migration of silica from the external surface to the internal surface of the particles. The dispersed silica phase stabilized the alumina surface area at severe high temperature conditions. Bulk silicic acid was also found to disperse onto alumina under analogous steaming conditions.     

Multiple-quantum-well GaInNAs-GaNAs ridge-waveguide laser diodesoperating out to 1.4 μm

In this letter, results from a ridge waveguide laser diode (LD) structure, with three GaInNAs quantum wells (QWs) and GaNAs barriers, are presented. The sample was grown by solid source molecular beam epitaxy with an RF plasma nitrogen source. These devices differ from previously reported GaInNAs QWs LDs that used GaAs as the barrier material. The introduction of nitrogen into the barriers reduces the spectral blue shift caused by post-growth annealing. Long wavelength emission out to 1.405 μm was observed. The devices exhibited threshold current densities as low as 1.5 kA/cm², high differential efficiency of 0.67 W/A, and a maximum output power of 350 mW     

Lower bound earthquake magnitude for probabilistic seismic hazard evaluation

This paper presents the results of a study that develops an engineering and seismological basis for selecting a lower-bound magnitude (LBM) for use in seismic hazard assessment. As part of a seismic hazard analysis the range of earthquake magnitudes that are included in the assessment of the probability of exceedance of ground motion must be defined. The upper-bound magnitude is established by earth science experts based on their interpretation of the maximum size of earthquakes that can be generated by a seismic source. The lower-bound or smallest earthquake that is considered in the analysis must also be specified.The LBM limits the earthquakes that are considered in assessing the probability that specified ground motion levels are exceeded. In the past there has not been a direct consideration of the appropriate LBM value that should be used in a seismic hazard assessment. This study specifically looks at the selection of a LBM for use in seismic hazard analyses that are input to the evaluation/design of nuclear power plants (NPPs). Topics addressed in the evaluation of a LBM are earthquake experience data at heavy industrial facilities, engineering characteristics of ground motions associated with small-magnitude earthquakes, probabilistic seismic risk assessments (seismic PRAs), and seismic margin evaluations. The results of this study and the recommendations concerning a LBM for use in seismic hazard assessments are discussed.     

Optimal scale factors for Gaussian field expansions for a circular aperture

Gaussian field expansions for circular aperture antennas are reviewed, and a method for finding optimal scales in these expansions is given, paralleling the method for rectangular antennas presented in an earlier paper. This procedure is shown to lead to approximations structured in the sense that the number of lobes in the approximation corresponds to the number of terms retained in the expansion. An example is given of the development of a cosine distribution from the aperture, through the Fresnel region, to the far field.     

Analysis of interinjection-locked oscillators for integrated phased arrays

The behavior of a system of coupled oscillators is shown to have potential applications in the generation of power for integrated phased antenna arrays. Nonlinear differential equations are derived to describe a system of oscillators coupled by an arbitrary frequency-dependent network. State-variable analysis of the linearized equations leads to closed-form solutions for one- and two-dimensional phased array systems. Experimental data for a VHF prototype system is presented, and practical considerations in system design are discussed.