Study of Microstructure Evolution during Semi-Solid Processing of an In-Situ Al Alloy Composite

In the present work, effect of pouring temperature (650°C, 655°C, and 660°C) on semi-solid microstructure evolution of in-situ magnesium silicide (Mg₂Si) reinforced aluminum (Al) alloy composite has been studied. The shear force exerted by the cooling slope during gravity driven flow of the melt facilitates the formation of near spherical primary Mg₂Si and primary Al grains. Shear driven melt flow along the cooling slope and grain fragmentation have been identified as the responsible mechanisms for refinement of primary Mg₂Si and Al grains with improved sphericity. Results show that, while flowing down the cooling slope, morphology of primary Mg₂Si and primary Al transformed gradually from coarse dendritic to mixture of near spherical particles, rosettes, and degenerated dendrites. In terms of minimum grain size and maximum sphericity, 650°C has been identified as the ideal pouring temperature for the cooling slope semi-solid processing of present Al alloy composite. Formation of spheroidal grains with homogeneous distribution of reinforcing phase (Mg₂Si) improves the isotropic property of the said composite, which is desirable in most of the engineering applications.     

Synthesis,characterization and bactericidal activity of silica/silver core–shell nanoparticles

Silica/silver core–shell nanoparticles (NPs) were synthesized by coating silver NPs on silica core particles (size ~300 ± 10 nm) via electro less reduction method. The core–shell NPs were characterized for their structural, morphological, compositional and optical behavior using X-ray diffraction, scanning electron microscopy, energy dispersive X-ray analysis and UV–Visible spectroscopy, respectively. The size (16–35 nm) and loaded amount of silver NPs on the silica core were found to be dependent upon reaction time and activation method of silica. The bactericidal activity of the NPs was tested by broth micro dilution method against both Bacillus subtilis (gram positive) and Escherichia coli ATCC25922 (gram negative) bacterium. The bactericidal activity of silica/silver core–shell NPS is more against E. coli ATCC25922, when compared to B. subtilis. The minimal inhibitory concentration of the core–shell NPs ranged from 7.8 to 250 μg/mL and is found to be dependent upon the amount of silver on silica, the core. These results suggest that silica/silver core–shell NPs can be utilized as a strong substitutional candidate to control pathogenic bacterium, which are otherwise resistant to antibiotics, making them applicable in diverse medical devices.     

A new approach to mining fuzzy databases using nearest neighbor classification by exploiting attribute hierarchies

Data classification is a well‐organized operation in the field of data mining. This article presents an application of the k‐nearest neighbor classification technique for mining a fuzzy database. We consider a data set in which attribute values have certain similarities in nature and analyze the observations for the domain of each attribute, on the basis of fuzzy similarity relations. The proposed technique is general and the presented case study demonstrates the suitability of using this fuzzy approach for mining fuzzy databases, especially when the database contains various levels of abstraction. © 2004 Wiley Periodicals, Inc. Int J Int Syst 19: 1277–1290, 2004.     

Long latency evoked potentials in a case of corpus callosum agenesia

Following monoaural stimulation, long latency auditory evoked potentials (LLAEPs) recorded from contralateral temporal areas have a shorter latency and larger amplitude than those recorded from the ipsilateral temporal areas. This observation agrees with the operational model drawn up in 1967 by Kimura, which assumes that only anatomically prevailing crossed auditory pathways are active during dichotic hearing, while direct pathways are inhibited. The inputs may then be conveyed to the contralateral cortex, from where they finally reach the ipsilateral temporal areas by means of interhemispheric commissures. It is this mechanism which may underline the right ear advantage for verbal stimuli and the left ear advantage for melodies observed when administering dichotic listening tasks. With the aim of verifying this hypothesis, we recorded temporal LLAEPs in a 21 year-old woman suffering from complex partial seizures, whose CT scan and MRI showed corpus callosum agenesia. Our data support the hypothesis that ipsilateral pathways are greatly inhibited by the contralateral pathways, and therefore auditory stimuli can be supposed to reach the contralateral auditory cortex from where they are transferred through the corpus callosum to the ipsilateral auditory cortex.     

Unsteady nonsimilar compressible boundary layer flow over a rotating sphere

Summary The problem of determining the development of the nonsimilar viscous compressible boundary layer flow with time over a rotating sphere is considered when both free stream velocity and rotation vary arbitrarily with time. Variations of skin friction, heat transfer and displacement thickness with mass injection, rotation, wall enthalpy and time are discussed.     

Direct synthesis of ZnO nanowire arrays on Zn foil by a simple thermal evaporation process

ZnO nanowire arrays were synthesized on zinc foil by a simple thermal evaporation process at relatively low temperature. Morphology and size controlled synthesis of the ZnO nanostructures was achieved by variation of the synthesis temperature, reaction time and the surface roughness of the substrate. A gas-solid and self-catalytic liquid-solid mechanism is proposed for the growth of nanowires at different temperatures. High-resolution transmission electron microscopy (HRTEM) showed that the as-grown nanowires were of single crystal hexagonal wurtzite structure, growing along the [101] direction. Photoluminescence exhibited strong UV emission at ～382?nm and a broad green emission at ～513?nm with 325?nm excitation. Raman spectroscopy revealed a phonon confinement effect when compared with results from bulk ZnO. The nanowire arrays also exhibited a field emission property.     

Multifunctional Photonics Nanoparticles for Crossing the Blood–Brain Barrier and Effecting Optically Trackable Brain Theranostics

Theranostic photonic nanoparticles (TPNs) that cross the blood–brain barrier (BBB) and efficiently deliver a therapeutic agent to treat brain diseases, simultaneously providing optical tracking of drug delivery and release, are introduced. These TPNs are constructed by physical encapsulation of visible and/or near‐infrared photonic molecules, in an ultrasmall micellar structure (<15 nm). Phytochemical curcumin is employed as a therapeutic as well as visible‐emitting photonic component. In vitro BBB model studies and animal imaging, as well as ex vivo examination, reveal that these TPNs are capable of transmigration across the BBB and subsequent accumulation near the orthotopic xenograft of glioblastoma multiforme (GBM) that is the most common and aggressive brain tumor whose vasculature retains permeability‐resistant properties. The intracranial delivery and release of curcumin can be visualized by imaging fluorescence produced by energy transfer from curcumin as the donor to the near‐infrared emitting dye, coloaded in TPN, where curcumin induced apoptosis of glioma cells. At an extremely low dose of TPN, a significant therapeutic outcome against GBM is demonstrated noninvasively by bioluminescence monitoring of time‐lapse proliferation of luciferase‐expressing U‐87 MG human GBM in the brain. This approach of TPN can be generally applied to a broad range of brain diseases.     

Development of building energy asset rating using stock modelling in the USA

The US Building Energy Asset Score helps building stakeholders quickly gain insight into the efficiency of building systems (envelope, electrical and mechanical systems). A robust, easy-to-understand 10-point scoring system was developed to facilitate an unbiased comparison of similar building types across the country. The Asset Score does not rely on a database or specific building baselines to establish a rating. Rather, distributions of energy use intensity (EUI) for various building use types were constructed using Latin hypercube sampling and converted to a series of stepped linear scales to score buildings. A score is calculated based on the modelled source EUI after adjusting for climate. A web-based scoring tool, which incorporates an analytical engine and a simulation engine, was developed to standardize energy modelling and reduce implementation cost. This paper discusses the methodology used to perform several hundred thousand building simulation runs and develop the scoring scales.     

Pigmented spindle cell nevus: a clinicopathologic analysis of ninety-five cases

BACKGROUND: Pigmented spindle cell nevus (PSCN) is often interpreted as a Spitz nevus or misdiagnosed as malignant melanoma. OBJECTIVE: The purpose of this study was to analyze the clinical and histologic features and to determine the biologic behavior of 95 cases of PSCN. METHODS: We reviewed clinical data, follow-up information, and microscopic features of all 95 cases of PSCN. RESULTS: PSCNs are dark brown to black, 3 to 6 mm in diameter, and occur most commonly on the extremities (75%) and back (16%) with a predilection for the legs. These lesions are more common in women in the third decade of life. Microscopically, PSCNs are characterized by uniform, spindle-shaped, pigmented melanocytes. Although some histologic features overlap with those in spindle and epithelioid cell nevus, PSCN is a separate entity. In addition, PSCN must be differentiated from malignant melanoma. Fifty-seven patients (60%) observed for an average of 6 years did not develop local recurrence or metastasis. CONCLUSION: PSCN is a distinctive, acquired, benign melanocytic lesion, that should not be confused with spindle and epithelioid cell nevus or malignant melanoma. Complete excision is recommended for treatment.     

Early Stage Automatic Strategy for Power-Aware Signal Processing Systems Design

Complexity management, portability and long term adaptivity are common challenges in different fields of embedded systems, normally colliding with the needs of efficient resource utilization and power balance. Image/signal processing systems, though required to offer a large variety of complex functions, have also to deal with battery-life limitations. Wearable signal processing systems, for example, should provide high performance and support new generation standards without compromising their portability and their long-term usability. These constraints challenge hardware designers: early stage trade-off analysis and power management automated techniques are helpful to guarantee a reasonable time-to-market. In the field of video codec specifications, the MPEG standard known as Reconfigurable Video Coding (RVC) framework addresses functional complexity and adaptivity leveraging on the intrinsic modularity of the dataflow model of computation, but it still lacks in offering power management support. The main contribution of this work is providing an automatic early-stage power management methodology to be adopted within the MPEG-RVC context. Starting from different high-level specifications, our mapping methodology identifies directly on the high-level models disjointed homogeneous logic clock regions, where the platform resources can be enabled/disabled together without affecting the overall system performance. To extend its usability to the RVC community, we have integrated this methodology within the Multi-Dataflow Composer (MDC) tool. MDC is a tool for on-the-fly reconfigurable signal processing platforms deployment. In this paper, we extended MDC to address power-aware multi-context systems. To prove the effectiveness of our work, a coprocessor for image and video processing acceleration has been assembled. This latter has been synthesized on a 90 nm ASIC technology, where demonstrated up to 90 % of reduction in the dynamic power consumption on different dataflow-intensive applications. The coprocessor has been implemented also on FPGA, confirming, partially, the benefits of adopting the proposed methodology.