Sialons — Promising Refractory and Ceramic Materials

Available data on the chemical composition and structure of sialon phases are reviewed. Properties of the phases and their potential applications are discussed.     

Solid Solutions in the LnAlO3–CaTiO3 (Ln = Dy, Y, Lu) Systems

The phase equilibria in the LnAlO₃–CaTiO₃ (Ln = Dy, Y, Lu) systems are investigated and their phase diagrams are constructed for the first time. The thermal stability of the prepared solid solutions with a perovskite structure is studied.     

RF antenna analysis with the ICANT code

The ICANT code computes self-consistently the surface current distribution on a 3D antenna model radiating in a plasma or vacuum and has been used to analyze the coupling properties of various antenna models. In this work it is used to assess near-fields generated by different versions of the TCABR (Tokamak Chauffage Alfvén wave heating experiment in Brazil) antenna as well as coupling properties of the TEXTOR tokamak in Forshungszentrum Jülich. Two different strap models planned for the TCABR antenna are shown to be practically equivalent in terms of maximum electric field. Textor coupling calculations are close to experimental values.     

Recombination lifetime profiling in very thin Si epitaxial layersused for bipolar VLSI

A recently proposed measurement technique (P. Spirito and G. Cocorullo, IEEE Trans. Electron Devices, vol.ED-32, no.9, p.1708-13, 1985) to evaluate the recombination lifetime along epitaxial layers is used to characterize the quality of very thin Si epitaxial layers used for bipolar technology. The experimental results show the ability of the technique to give accurate and detailed information on the quality of epilayers that could be useful in monitoring and improving the growth process. The experimental results show that the lifetime values in thin epilayers are not correlated with doping profiles in the same layers; moreover, they are only slightly dependent on different processes used to make the test devices     

Non-darcy natural convection from a heated vertical plate in saturated porous media with mass transfer

The nonsimilar and self-similar flows for the steady natural convection over a vertical heated surface in a saturated porous medium with mass transfer using non-Darcy model have been studied under boundary layer approximations. The differential equations governing both the nonsimilar and self-similar flows have been solved numerically using an implicit finite-difference scheme developed by Keller. The results indicate that both heat transfer and velocity field are appreciably affected by the modified Grashof number and mass transfer except that the effect of the modified Grashof number on the heat transfer for large suction is very small. It is found that the maximum velocity occurs at the wall and it increases as the modified Grashof number or injection increases.     

Undesirable sensory properties of the dried pea (Pisum sativum). The rôle of saponins

The rôle of saponins in the undesirable sensory properties of the dried pea P sativum is reported. The sensory properties of isolated soyasaponin I are defined and described as bitter, astringent and metallic. The distribution of saponin in various air-classified pea flour fractions shows that the protein-rich fraction may contain sufficient saponin to cause undesirable tastes.     

Effects of interstitial oxygen on microstructure and mechanical properties of Ti-48Al-2Cr-2Nb with fully lamellar and duplex microstructures

The effect of added oxygen in the range of 1000 to 4000 wt ppm on the microstructures of a Ti-48Al-2Cr-2Nb alloy has been investigated and compared to the microstructures for a high-purity alloy. For specimens cooled from theα phase, interstitial oxygen stabilizes the lamellar microstructure with respect toγ grains, with higher than equilibrium values for theα ₂ volume fraction. For specimens cooled from theα +γ phase field, the lamellar microstructure still tends to be favored by oxygen, but it is found that the phase volume fractions are not significantly different from equilibrium values. This suggests that interstitial O essentially reduces the kinetics of theα toα +γ transformation. Thus, interstitial oxygen will have a strong effect on microstructures obtained by continuous cooling fromα, but significantly less on those, such as the duplex microstructure, obtained by long treatment in theα +γ phase field. In general, increased O content is well correlated with reduced ductility. Finally, the role of interstitial oxygen on this phase transformation is discussed.     

Restoration challenges for urban rivers.

Urban sources account for significant quantities of important diffuse pollutants, and urban watercourses are typically badly polluted. As well as toxic metals, hydrocarbons including PAHs, and suspended matter, priority urban pollutants include faecal pathogens and nutrients. Can urban watercourses be restored by sufficient reductions in pollution loads? Case studies in the UK and Sweden provide insights and some grounds for optimism. A major trans-Atlantic review of the performance of best management practices (BMPs) is informing BMP planning. New approaches such as the maximisation of self-purification capacity in the receiving waters may also need to be developed, alongside BMPs at source. Other initiatives in Europe, USA and China, including collaborative projects, are trying to address the intractable issues such as persistent pollutants from transport and urban infrastructure. The challenge is daunting, but there are clear ways forward and future research needs are evident.     

Photoinduced conversion of radiation polarization in integratedoptics components based on LiNbO3

Two photoinduced effects in LiNbO₃ optical waveguides (unidirectional waveguide mode conversion from ordinary to extraordinary polarization and radiation coupling out of waveguides with polarization plane rotation) are discussed. The circular photovoltaic tensor component in LiNbO₃ is determined experimentally, and a photovoltaic mechanism to explain photoinduced radiation coupling out of waveguides is proposed. The impact of the effects discovered on the performance of phase modulators is discussed