Delivery of video mail on the World Wide Web

This study was initiated to examine the feasibility of providing multimedia mail, in particular video mail, on the existing World Wide Web platform. In this instance, the Web browser will act as the user agent of the mailing system. With this, users will be able to compose, send and read video mail directly on the Web. This paper examines a number of possible system architectures that can be employed for the development of video mail. Based on the following key issues: portability of system, flexibility of system, Internet standard support, security and authentication, and message compression and storage, a final architecture was selected to build video mail. The approach taken is that the system will be interfaced to the Web using a standard HyperText Transfer Protocol (HTTP) server and a standard Web browser. This is achieved through the use of Common Gateway Interface (CGI) programs and forms which reside in a standard HTTP server to provide the functionality of video mail, and a separate mail server for the storage and management of messages. This will cause the HTTP server to behave as if it is an electronic mail (E-mail) system. Video mail has been successfully implemented at the School of Applied Science, Nanyang Technological University, Singapore. The development work has been carried out on a Sun SPARC5 workstation and the Typhoon relational database system was used to construct the mail server. All software codes were written in C or C++. A video capturing application used in conjunction with a SunVideo card has been developed for video and audio recording. The paper also addresses implementation issues pertaining to the use of CGI programs, mail server development, and video and audio management.     

New Functional Polymers and Materials Based on 2,2′:6′,2″‐Terpyridine Metal Complexes

New inorganic–organic hybrid structures based on metal complexes have become of increasing interest over the last few decades in the search for new materials. Many different polypyridyl metal complexes have been investigated. Recently, a strong increase in interest regarding 2,2′:6′,2″‐terpyridine has been observed. In particular, octahedral bis‐2,2′:6′,2″‐terpyridine metal complexes offer the advantages of increased symmetry and, in the case of ruthenium(III )/ruthenium(II ) complexation, an entrance to a directed complexation technique. Apart from the combination with polymeric systems, ordered inorganic–organic structures on surfaces are becoming better understood concurrently with the development of sophisticated nanotechnology characterization techniques. There are many ongoing efforts that include terpyridine complex structures, especially concerning photophysical processes such as solar light to energy conversion. This review deals with the incorporation of terpyridine complexes into polymeric structures such as poly(ethylene glycol), poly(styrene), dendrimers, biomacromolecules, micelles, and resins, as well as the combination of terpyridine complexes with surfaces for electrocatalytic, photophysical, and self‐assembly purposes.     

Nanometer edge and surface imaging using optical scatter

Imaging of edges to nanometer resolution using a novel non-contact technique is presented. This technique relies on positioning an optical beam to the edge, and simultaneously scanning, and measuring differential changes in off-specular scatter. Data may be used to calculate the radius at the edge to high accuracy. The experimental apparatus is capable of producing diffraction images of features on surfaces arising from processes used in sample preparation. Images of the cleaved edge of an optical fiber, an Au pad on Si, and cleaved quartz measured on this apparatus are presented. This technique could also be utilized to analyze cleaved laser diodes, micro-optics, MEMS devices, and diamond cutting tools.     

A note on the Jaccardized Czekanowski similarity index

It is shown that the “Jaccardized Czekanowski index” is actually a reinterpretation of the Ru?i?ka index. Thereby, it is proved that its one-complement is a true distance function, which makes it particularly suitable for use in similarity studies even with multidimensional statistical techniques.     

Smart metal sheets by direct functional integration of piezoceramic fibers in microformed structures

Microassembly of piezoceramic fibers in micro cavities at the surface of sheet metal is a novel approach for high volume production of smart adaptronic structural metal parts. In this paper a technology, manufacturing processes and characterization results of metal sheets with an active piezo-metal substructure based on directly integrated piezoceramic fibers are described. The processes include micro-milling of cavities in sheet metal, precision grinding of piezoceramic fibers, PECVD insulating layers with high dielectric strength, microassembly and force-locked joining by forming. In experiments, measurements of the surface roughness and geometric parameters of the piezoceramic fibers and micro cavities were performed. Further, the electrical properties of the insulation coatings were measured. The sensor function of the piezo-metal substructure was proven by a mechanical excitation resulting in a proportional measured sensor signal.     

Growth condition dependence of unintentional oxygen incorporation in epitaxial GaN

Growth conditions have a tremendous impact on the unintentional background impurity concentration in gallium nitride (GaN) synthesized by molecular beam epitaxy and its resulting chemical and physical properties. In particular for oxygen identified as the dominant background impurity we demonstrate that under optimized growth stoichiometry the growth temperature is the key parameter to control its incorporation and that an increase by 55?°C leads to an oxygen reduction by one order of magnitude. Quantitatively this reduction and the resulting optical and electrical properties are analyzed by secondary ion mass spectroscopy, photoluminescence, capacitance versus voltage measurements, low temperature magneto-transport and parasitic current paths in lateral transistor test structures based on two-dimensional electron gases. At a growth temperature of 665?°C the residual charge carrier concentration is decreased to below 10¹⁵ cm^?3, resulting in insulating behavior and thus making the material suitable for beyond state-of-the-art device applications.     

Significant Enhancement of the Dielectric Constant through the Doping of CeO2 into HfO2 by Atomic Layer Deposition

Films of CeO₂ were deposited by atomic layer deposition (ALD) using a Ce(mmp)₄ [mmp = 1‐methoxy‐2‐methyl‐2‐propanolate] precursor and H₂O reactant. The growth characteristics and film properties of ALD CeO₂ were investigated. The ALD CeO₂ process produced highly pure, stoichiometric films with polycrystalline cubic phases. Using the ALD CeO₂ process, the effects of Ce doping into an HfO₂ gate dielectric were systematically investigated. Regardless of Ce/(Ce + Hf) composition, all ALD Ce_xHf_1?xO₂ films exhibited constant growth rates of approximately 1.3 Å/cycle, which is essentially identical to the ALD HfO₂ growth rates. After high‐temperature vacuum annealing at 900°C, it was verified, based on X‐ray diffraction and high‐resolution cross‐sectional transmission electron microscopy results, that all samples with various Ce/(Ce + Hf) compositions were transformed from nanocrystalline to stabilized cubic or tetragonal HfO₂ phases. In addition, the dielectric constant of the Ce_xHf_1?xO₂ films significantly increased, depending on the Ce doping content. The maximum dielectric constant value was found to be nearly 39 for the Ce/(Ce + Hf) concentration of ~11%.     

Electrochemical investigations on amorphous Fe-base alloys for alkaline water electrolysis

In this work different amorphous melt-spun Fe-alloys (Fe₈₂B₁₈, Fe₈₀Si₁₀B₁₀, Fe₆₀Co₂₀Si₁₀B₁₀) were investigated as cathode materials for the alkaline electrolysis of water. In particular, the influence of cobalt as well as the metalloids boron and silicon on the activity for the hydrogen evolution reaction (HER) was studied in 1 M KOH at 298 K using cyclic voltammetric, galvanostatic and polarization techniques. The electrocatalytic activity was evaluated in the view of the overpotential. It was found that cyclic voltammetric techniques can be used to activate the melt-spun Fe-alloys strongly. Different cyclic voltammetric activation procedures are discussed and the influence of the sweep rate and the potential window on the HER activity was elucidated. The experimental data indicate that the addition of metalloids and, most importantly, of cobalt improves the HER activity of the materials. Thus, the overpotential can be reduced by 200 mV compared to polycrystalline Ni.