Phase-field modeling of eutectic structures on the nanoscale: the effect of anisotropy

A simple phase-field model is used to address anisotropic eutectic freezing on the nanoscale in two (2D) and three dimensions (3D). Comparing parameter-free simulations with experiments, it is demonstrated that the employed model can be made quantitative for Ag–Cu. Next, we explore the effect of material properties and the conditions of freezing on the eutectic pattern. We find that the anisotropies of kinetic coefficient and the interfacial free energies (solid–liquid and solid–solid), the crystal misorientation relative to pulling, the lateral temperature gradient play essential roles in determining the eutectic pattern. Finally, we explore eutectic morphologies, which form when one of the solid phases are faceted, and investigate cases, in which the kinetic anisotropy for the two solid phases is drastically different.     

Studies on the Photocatalytic Electron Pooling of Graphene Oxide Hybrids Decorated with Electron Donor and Electron Acceptor Molecules

Photocatalytic behavior of a recently synthesized, single layer graphene oxide (SLGO) decorated with an electron donor, zinc phthalocyanine (ZnPc) and an electron acceptor, fulleropyrrolidine (C₆₀) donor-acceptor hybrid is demonstrated. Electron accumulation in the form of one-electron reduced product of methyl viologen was obtained in high yields in an electron pooling experiment involving the ZnPc-SLGO-C₆₀ hybrid and a sacrificial electron donor compared with control hybrids involving either ZnPc-SLGO or SLGO-C₆₀ hybrids. This novel property of ZnPc-SLGO-C₆₀ hybrid has been ascribed to the proximity effect offered by GO with covalently linked donor and acceptor entities on its surface. The present studies reveal that the ZnPc-SLGO-C₆₀ hybrid is a suitable catalyst for solar fuel production.     

Metabolomics Analysis Reveals Specific Novel Tetrapeptide and Potential Anti-Inflammatory Metabolites in Pathogenic Aspergillus species

Infections related to Aspergillus species have emerged to become an important focus in infectious diseases, as a result of the increasing use of immunosuppressive agents and high fatality associated with invasive aspergillosis. However, laboratory diagnosis of Aspergillus infections remains difficult. In this study, by comparing the metabolomic profiles of the culture supernatants of 30 strains of six pathogenic Aspergillus species (A. fumigatus, A. flavus, A. niger, A. terreus, A. nomius and A. tamarii) and 31 strains of 10 non-Aspergillus fungi, eight compounds present in all strains of the six Aspergillus species but not in any strain of the non-Aspergillus fungi were observed. One of the eight compounds, Leu–Glu–Leu–Glu, is a novel tetrapeptide and represents the first linear tetrapeptide observed in Aspergillus species, which we propose to be named aspergitide. Two other closely related Aspergillus-specific compounds, hydroxy-(sulfooxy)benzoic acid and (sulfooxy)benzoic acid, may possess anti-inflammatory properties, as 2-(sulfooxy)benzoic acid possesses a structure similar to those of aspirin [2-(acetoxy)benzoic acid] and salicylic acid (2-hydroxybenzoic acid). Further studies to examine the potentials of these Aspergillus-specific compounds for laboratory diagnosis of aspergillosis are warranted and further experiments will reveal whether Leu–Glu–Leu–Glu, hydroxy-(sulfooxy)benzoic acid and (sulfooxy)benzoic acid are virulent factors of the pathogenic Aspergillus species.     

A Web-based virtual environment for operator training [for powersystems]

The wide accessibility and low cost of virtual reality (VR) on the World Wide Web with the advent of the Virtual Reality Modelling Language (VRML) and VRML interpreters makes it ideal for use in providing cost-effective training for operators in selected complex technical environments. This paper presents SEDA-VRML, a VR-based learn-by-doing system developed for the training of maintenance workers in the troubleshooting and inspection of power transformers at Hydro-Quebec that is accessible from a Web browser. SEDA-VRML is a prototype application of a reuse-driven design incorporating VRML, Java and an expert system within a user interface system (UIS) architecture. The paper describes the functionality and design principles of SEDA-VRML, with key implementation results, to show how SEDA-VRML's design can indeed answer to the limitations of VRML to act as a cost-effective alternative to traditional operator training systems for operator training in VR, as well as a basis for the rapid development of future operator training systems     

Altering Arabidopsis Oilseed Composition by a Combined Antisense-Hairpin RNAi Gene Suppression Approach

Antisense (AS) and hairpin (HP) RNA interference (RNAi) targeted gene suppression technologies have been used to modify seed oil composition. Larger numbers of AS transgenics have to be screened to achieve a targeted level of suppression compared to RNAi. We hypothesized combining AS with RNAi might result in enhanced gene suppression compared to either method individually. AS and HP-RNAi were combined as hairpin antisense (HPAS) constructs containing ~125 bp sense and antisense portions of an untranslated region of the target gene separated by an intron containing an antisense copy of a portion of the target coding region. The Δ12-desaturase FAD2, the ω3-desaturase FAD3 and β-ketoacyl-ACP synthase (KAS) II were targeted in Arabidopsis to evaluate changes in oil composition with AS, HP and HPAS constructs driven by the phaseolin promoter. Modest but statistically significant enhancements in oilseed phenotypes were observed with HPAS relative to AS and HP-RNAi. Phenotypes for HPAS suppression of FAD2 and FAD3 were indistinguishable from their strongest mutant alleles. Our data suggest that HPAS may be useful for: (1) achieving levels of suppression comparable to those of gene knockouts in a tissue specific manner. (2) Maximizing suppression of suboptimal RNAi constructs and (3) minimizing the screening of transgenics to achieve desired oilseed composition.     

All-Optical Multicast Switch Employing Raman-Assisted FWM in Dispersion-Shifted Fiber

We demonstrate an all-optical multicast switch with the capability to select five reconfigurable channel groups with six output multicast channels using three control wavelengths at 10 Gb/s using Raman-assisted four-wave mixing in dispersion-shifted fiber. All the output channels comply with the 100 GHz (i.e., 0.8 nm) spaced International Telecommunication Union (ITU) grid.