Extractives in the cones of Pinus species

Amount and composition of lipophilic and hydrophilic extractives were analyzed in the cones of five coniferous species, namely Pinus halepensis, P.?brutia, P.?pinea, P. sylvestris and P.?nigra, growing natively in Turkey. Lipophilic extractives amounts, identified by GC, were found to be the highest in P.?brutia (35.1?mg?g^?1) and P.?halepensis (31.3?mg?g^?1) while the lowest values were found in P.?sylvestris (9.0?mg?g^?1). Resin acids were the major lipophilic group in all cones. The predominant resin acids were abietic acid in P.?pinea, P.?halepensis and P.?brutia, dehydroabietic acid in P.?sylvestris, and isopimaric acid in P.?nigra. Compared to lipophilic extractives, the amount of total hydrophilic extractives showed similar gravimetric values while sugars and sugar alcohols were the dominant group.     

Al–Ti–B grain refiners via powder metallurgy processing of Al/K2TiF6/KBF4 powder blends

The response to thermal exposure of ball-milled Al/K₂TiF₆/KBF₄ powder blends was investigated to explore the potential of PM processing for the manufacture of Al–Ti–B alloys. K₂TiF₆ starts to be reduced by aluminium as early as 220 °C when ball-milled Al/K₂TiF₆/KBF₄ powder blends are heated. The reaction of KBF₄ with aluminium follows soon after. The Ti and B thus produced are both solutionized in aluminium before precipitating out as Al₃Ti and TiB₂. All these reactions take place below the melting point of aluminium. The ball-milled Al/K₂TiF₆/KBF₄ powder blends heat treated at approximately 525 °C can be compacted to produce Al–Ti–B pellets with in situ formed Al₃Ti and TiB₂ particles. These pellets are shown to be adequate grain refiners for aluminium alloys.     

Analysis of macro segregation in twin-roll cast aluminium strips via solidification curves

A porous NiO/yttria-stabilized zirconia (YSZ) anode substrate for zirconia-based tubular solid oxide fuel cells (SOFCs) was prepared by the gelcasting. The effect of the impregnation of SDC in the substrate was studied. Electrochemical impedance spectroscopy and I–V and I–P curves of the cells were measured. Scanning electron microscopy (SEM) was used to observe the microstructures. The results indicate that the performance of the cell can be significantly improved by incorporating the nano-structured SDC particles in the substrate. The peak power density of the cell is increased by about 60% and the area specific resistance (ASR) decreased by about 47% at 700 °C, compared with the unmodified cells. It is explained as the extended triple-phase boundary (TPB) in the anode substrate and the excellent electrocatalytic property of SDC. It is also found that the nano-scale SDC particles change a lot during the reduction of the anode substrate, and the morphology of the resultant SDC particles on the metal Ni is significantly different from that on the YSZ. After the long-term operation, the morphology of the SDC particles on the Ni changes again, but that on the YSZ keeps almost unchanged.     

Microstructural characterization of a rapidly-solidified Al-12 wt% Si alloy

Optical, electron metallography and X-ray diffraction techniques were employed to characterize the microstructure of a rapidly solidified Al-12 wt% Si alloy. Ribbons produced with the planar flow casting process at a cooling rate of 10⁶ Ks^–1, had a very fine cellular structure of Al and nanosize Si particles which are distributed inside and at the boundaries of these cells. Thinner sections (t<30 m) have apparently experienced higher cooling rates and show, in addition to a cellular structure, a distinct zone which is featureless at optical microscope magnifications.     

Ahp model for the selection of partner companies in virtual enterprises

Rising product variety and complexity, shorter time frames to respond, and the continual need to gain new capabilities through innovativeness force the trend of outsourcing to be replaced by strategic alliances, where enterprises or individuals work together towards a common goal and share their responsibilities as well as their profits. Recent developments in information technology have enabled relatively inexpensive, reliable and fast networking to support such alliances in real time. In this context, the virtual enterprise (VE) represents an appropriate cooperation alternative and competitive advantage for the enterprises. VE is a temporary network of independent companies -- suppliers, customers, even rivals -- linked by information technology (IT) to share skills, costs and access to one another’s markets. In this emerging business model of virtual enterprise, the decision support functionality, which addresses issues such as partner company selection, is an important domain to be studied. In this paper, we propose an analytic hierarchy process model to contribute in the selection of the partner companies in the virtual enterprises. A case example is also covered to validate the feasibility of the adoption of the model in virtual enterprise situations.     

Broadband Enhanced Chirality with Tunable Response in Hybrid Plasmonic Helical Metamaterials

Designing broadband enhanced chirality is of strong interest to the emerging fields of chiral chemistry and sensing, or to control the spin orbital momentum of photons in recently introduced nanophotonic chiral quantum and classical optical applications. However, chiral light-matter interactions have an extremely weak nature, are difficult to control and enhance, and cannot be made tunable or broadband. In addition, planar ultrathin nanophotonic structures to achieve strong, broadband, and tunable chirality at the technologically important visible to ultraviolet spectrum still remain elusive. Here, these important problems are tackled by experimentally demonstrating and theoretically verifying spectrally tunable, extremely large, and broadband chiroptical response by nanohelical metamaterials. The reported new designs of all-dielectric and dielectric-metallic (hybrid) plasmonic metamaterials permit the largest and broadest ever measured chiral Kuhn's dissymmetry factor achieved by a large-scale nanophotonic structure. In addition, the strong circular dichroism of the presented bottom-up fabricated optical metamaterials can be tuned by varying their dimensions and proportions between their dielectric and plasmonic helical subsections. The currently demonstrated ultrathin optical metamaterials are expected to provide a substantial boost to the developing field of chiroptics leading to significantly enhanced and broadband chiral light-matter interactions at the nanoscale.     

Investigation of photocatalytic properties of TiO2 nanoparticle coating on fly ash and red mud based porous ceramic substrate

Titanium dioxide is one of the best semiconducting photocatalysts available for photocatalytic cleaning applications. Especially nano-sized TiO₂ particles deposited on porous substrates can be utilized as a filter for solid and liquid media. On the other hand, red mud and thermal plant fly ash are hazardous wastes that are produced in large quantities. Recycling/reuse of these waste material in a porous ceramic production would be beneficial both for environmental and economical issues. In the present study, a porous substrate was produced from red mud and fly ash with varying ratios and additives of H₃BO₃, CaCO₃, and MgCO₃ for lowering the melting temperature and porosity formation. Sintered ceramics were then coated with nano-sized TiO₂ particles by the sol-gel method. Ultrasonic dispersion of nano-sized TiO₂ nanoparticles was also utilized as an alternative method for impregnation of nanoparticles into the porous structure of the ceramic substrate. Finally, photocatalytic activities and degradation of methylene blue (MB) under UV radiation of substrates were investigated. According to the SEM investigations, the sol-gel method was observed to be a better way of nanoparticle deposition because deposited particles are homogenous throughout the ceramic body. Also, this method provides lower particle sizes than the ones that were deposited by the ultrasonic dispersion method. This results in higher surface area and better photocatalytic activities.