Microstructure and hardness of Mg-based composites reinforced with Mg<Subscript>2</Subscript>Si particles

Magnesium powders were mechanically alloyed with SiO₂ powder particles having different particle sizes using high-energy ball milling techniques under Ar atmosphere for 1 h. The powders were consolidated with cold pressing under 560 MPa. They were then sintered at 550°C for 45 min under Ar atmosphere. The composites obtained on the Mg-SiO₂ system were investigated using the Archimedes principle, a differential scanning calorimeter, X-ray diffraction, optic microscopy, and scanning electron microscopy. For the mechanically alloyed powders, the solid-state reaction of the synthesis of Mg₂Si and MgO progressed further during sintering of the materials. The results showed that the strengthening mechanisms were dependent on dispersion hardening of fine Mg₂Si and MgO particulates dispersed homogeneously in the matrix.     

A system to detect houses and residential street networks in multispectral satellite images

Maps are vital tools for most government agencies and consumers. However, their manual generation and updating is tedious, time consuming, and expensive. To address these concerns, we are developing automated techniques. In this paper, we restrict our attention to residential regions. These regions provide a challenge, testing the current limits of automated image analysis. Such regions are also typically areas of rapid growth and development and, therefore, are of interest from the applications perspective. In previous studies, we introduced statistical measures to extract these kinds of regions from satellite images [in: Proceedings of the International Conference on Pattern Recognition, vol. 1, 2002, p. 127, IEEE Trans. GeoRS (2003), IEEE Trans. PAMI]. As the next step toward automatic map generation, here we introduce a novel system to detect houses and street networks in IKONOS multispectral images. These images have one meter panchromatic resolution with 4 m resolution in the spectral bands. Our system consists of four major components: multispectral analysis to detect cultural activity, segmentation of regions of possible human activity (based on the surface material), decomposition of the segmented images, and graph theoretical algorithms over the decompositions to extract the street network and to detect houses. We tested our system on a large and diverse data set. Our results indicate the usefulness of our system in detecting houses and street networks, hence generating automated maps.     

Random generation of monotonic functions for Monte Carlo solution of qualitative differential equations

We present improvements to the function representation and generation method used in the Monte Carlo analysis of incomplete ordinary differential equations. Our method widens the scope of the technique to cover cases in which no envelopes have been specified for the function under consideration, thereby extending the applicability of the Monte Carlo approach to the full repertoire of models developed for qualitative reasoning algorithms, and paving the ground for the integrated operation of these two highly complementary techniques. Our new representation does not entail unjustified implicit assumptions about the shape of the generated functions, and provides better coverage of the space of models defined by the input specifications. Our simulator (MOCASSIM) also has the capability of imposing additional restrictions (e.g., convexity) on function shapes, which is particularly useful when the Monte Carlo technique is applied for solving system dynamics problems.     

Effect of the particle size of finishing chemicals on the color assessment of treated cotton fabrics

Color change is one of the important side effects of textile treatments to consider. This article evaluates the effect of the particle size of commonly used finishing chemicals (fluorocarbon resins and dimethyloldihydroxylethylene urea reagents) on color assessment by studying instrumental analyses, and it is reported that the smaller the particle size is, the higher the surface reflectance is, and the less the color change can be achieved. On the other hand, the effect of the particle size is not significant on color assessment after abrading cycles. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Methodology for Predicting Cooling Water Effects on Fish

The mathematical model presented here predicts the long-term effects of once-through cooling water systems on local fish populations. The fish life cycle model simulates different life stages of fish by using appropriate expressions representing growth and mortality rates. The heart of the developed modeling approach is the prediction of plant-caused reduction in total fish population by estimating recruitment to adult population with and without entrainment of ichthyoplankton and impingement of small fish. The model was applied to a local fish species, gilthead (Sparus aurata), for the case of a proposed power plant in the Aegean region of Turkey. The simulations indicate that entrainment and impingement may lead to a population reduction of about 2% to 8% in the long run. In many cases, an impact of this size can be considered rather unimportant. In the case of sensitive and ecologically valued species facing extinction, however, necessary precautions should be taken to minimize or totally avoid such an impact.     

Characterization and mechanical properties of TiO2 nanotubes formed on titanium by anodic oxidation

The well-ordered titanium dioxide (TiO₂) nanotube array surfaces were formed at different voltages such as 20 V, 40 V, 60 V, 80 V and 100 V for 1 h on cp-Ti by anodic oxidation (AO) technique. And then, to improve crystallinity of the surface, heat treatment was applied at 450 °C for 1 h to all surfaces without any morphological changing. The surface and cross sectional morphology, elemental structure, phase composition, functional groups, roughness and thickness, wettability and mechanical results were investigated by SEM, EDX, XRD, FT-IR, AFM, contact angle measurement device and nanoindentation tester, respectively. Mainly, anatase- and rutile-TiO₂ phases were obtained at post-heat treatment whereas only, Ti phase was detected on AO surfaces at pre-heat treatment. All nanotube structures and the elements of Ti and O were uniformly distributed through the whole surface. The roughness and thickness of tube structures usually increased with increasing voltage values and measured. The roughness and thickness values were measured as 10.67–111.97 nm and 0.21–1.92 μm, respectively. TiO₂ nanotube surfaces exhibited hydrophobic behaviors with respect to plain Ti surface. Furthermore, mechanical properties such as hardness and elastic modulus of the coating produced at minimum voltage were great compared to ones at higher voltage and plain Ti surface under a Berkovich indenter due to phase structure, homogeneity and density of nanotube structures.     

Rapamycin Alternatively Modifies Mitochondrial Dynamics in Dendritic Cells to Reduce Kidney Ischemic Reperfusion Injury

Dendritic cells (DCs) are unique immune cells that can link innate and adaptive immune responses and Immunometabolism greatly impacts their phenotype. Rapamycin is a macrolide compound that has immunosuppressant functions and is used to prevent graft loss in kidney transplantation. The current study evaluated the therapeutic potential of ex-vivo rapamycin treated DCs to protect kidneys in a mouse model of acute kidney injury (AKI). For the rapamycin single (S) treatment (Rapa-S-DC), Veh-DCs were treated with rapamycin (10 ng/mL) for 1 h before LPS. In contrast, rapamycin multiple (M) treatment (Rapa-M-DC) were exposed to 3 treatments over 7 days. Only multiple ex-vivo rapamycin treatments of DCs induced a persistent reprogramming of mitochondrial metabolism. These DCs had 18-fold more mitochondria, had almost 4-fold higher oxygen consumption rates, and produced more ATP compared to Veh-DCs (Veh treated control DCs). Pathway analysis showed IL10 signaling as a major contributing pathway to the altered immunophenotype after Rapamycin treatment compared to vehicle with significantly lower cytokines Tnfa, Il1b, and Il6, while regulators of mitochondrial content Pgc1a, Tfam, and Ho1 remained elevated. Critically, adoptive transfer of rapamycin-treated DCs to WT recipients 24 h before bilateral kidney ischemia significantly protected the kidneys from injury with a significant 3-fold improvement in kidney function. Last, the infusion of DCs containing higher mitochondria numbers (treated ex-vivo with healthy isolated mitochondria (10 µg/mL) one day before) also partially protected the kidneys from IRI. These studies demonstrate that pre-emptive infusion of ex-vivo reprogrammed DCs that have higher mitochondria content has therapeutic capacity to induce an anti-inflammatory regulatory phenotype to protect kidneys from injury.     

Polymerization of pyrrole derivatives on polyacrylonitrile matrix,FTIR–ATR and dielectric spectroscopic characterization of composite thin films

Oxidative polymerization of acrylonitrile (AN) initiated by Ce(IV)–oxalic acid redox system in the aqueous medium was performed and polyacrylonitrile (PAN)/polypyrrole (PPy) composite thin films were prepared by polymerization of pyrrole on polyacrylonitrile matrix. Effect of concentration of pyrrole derivatives on the resulting polymeric film properties was investigated. The influence of the pyrrole derivative type and content on the dielectric permittivity, dielectric loss and electrical properties of the composite films were analyzed in the frequency range from 0.05 Hz to 10 MHz. For a selected concentration of 200 μl of composite films at 10⁷ Hz, the conductivity was found to be in the following order: PAN–PPy < PAN–PNMPy < PAN–PNPhPy. Dielectric constant increase of the composite films was more obvious when the quantity of n-phenyl pyrrole was increased. A linear relationship was observed between the absorbances (FTIR–ATR) and conductivities (dielectric spectroscopy).     

The effect of a SiC cap on the growth of epitaxial graphene on SiC in ultra high vacuum

Thin and homogeneous graphenes with excellent thickness uniformity were produced on the carbon-rich surface of a SiC crystal using an ultra high vacuum technique. The sample surface was capped by another SiC substrate with a silicon-rich face to form a shallow cavity between them. During the graphene growth by high temperature annealing, silicon atoms sublimated from the capped sample were trapped inside the cavity between the two substrates. The confined vapor phase silicon maintains a relatively high partial pressure at the sample surface which significantly reduces the extremely high growth rate of epitaxial graphene to an easily controllable range. The structure and morphology of the graphene samples grown with this capping method are characterized by low energy electron diffraction and Raman spectroscopy and the results are compared with those of layers grown on an uncapped sample surface. The results show that capping yields much thinner graphene with excellent uniformity.     

Optoelectronic and thermoelectric response of Ca<Subscript>5</Subscript>Al<Subscript>2</Subscript>Sb<Subscript>6</Subscript> to shift of band gap from direct to indirect

The structural, optoelectronic and thermoelectric properties of Ca₅Al₂Sb₆ under applied external pressures have been studied using the full potential linear augmented plane wave method. WIEN2k code is used with considering the generalized gradient approximation (GGA), modified Becke–Johnson (MBJ) and modified Becke–Johnson?+?spin orbit (mBJ?+?SO) functionals based on density functional theory (DFT). From electronic results, the size of the band gap decreases with increasing pressure and the nature of the band gap shift from direct to the indirect. In high pressure (>35.7 GPa by mBJ?+?SO), the band gap is also completely disappeared and the nature of compound is changed to the metallic. The calculated anisotropic optical properties such as the static dielectric function, increase with decreasing the size of band gap and increasing of pressure. As a novel result, the thermoelectric performance of n-type and p-type doping of Ca₅Al₂Sb₆ is related to the value of pressure. According to the thermoelectric results, the n-type one has the highest ZT in comparison with the p-type Ca₅Al₂Sb₆ material.