SCCN: A Time-Effective Hierarchical Interconnection Network for Network-On-Chip

Mobile Networks and Applications - The needed time to send and receive a message among two nodes in an interconnection network has a fundamental role in determining the performance of this network....     

High-Density Frenkel Defects as Origin of N-Type Thermoelectric Performance and Low Thermal Conductivity in Mg3Sb2-Based Materials

Mg₃Sb₂-based intermetallic compounds with exceptionally high thermoelectric performance exhibit unconventional n-type dopability and anomalously low thermal conductivity, attracting much attention to the underlying mechanisms. To date, investigations have been limited to first-principle calculations and thermodynamic analysis of defect formation, and detailed experimental analysis on crystal structure and phonon modes has not been achieved. Here, a synchrotron X-ray diffraction study clarifies that, against a previous view of a simple crystal structure with a small unit cell, Mg₃Sb₂ is inherently a heavily disordered material with Frenkel defects, charge-neutral defect complexes of cation vacancies and interstitials. Ionic charge neutrality preserved in Mg₃Sb₂ is responsible for exotic n-type dopability, which is unachievable for other Zintl phase materials. The thermal conductivity of Mg₃Sb₂ exhibits deviation from the standard T⁻¹ temperature dependency with strongly limited phonon transport due to a strain field. Inelastic X-ray scattering measurement reveals enhanced phonon scattering induced by disorder. The results will draw renewed attention to crystal defects and disorder as means to explore new high-performance thermoelectric materials.     

Organic–inorganic hybrid materials. II. Preparation and properties of higher silica containing polycarbonate–silica hybrid materials

The sol–gel reaction of a polycarbonate (PC) oligomer having triethoxysilyl groups at both ends of the PC chain (PCS) with a tetraethoxysilane or tetramethoxysilane oligomer provided transparent or semitransparent films of higher silica containing organic–inorganic hybrid materials (HSPC‐HMs). The films were superior to those from PC and from PCS in terms of the morphological homogeneity, heat resistance, and surface hardness. The HSPC‐HM films had minimum oxygen permeability at a PCS/tetraethoxysilane ratio of 3/7. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4273–4279, 2006     

Sequence distribution of cis-1,4- and trans-1,4-units in polyisoprenes

The ¹³C n.m.r. spectra of chicle polyisoprene and cis-trans isomerized 1, 4-polyisoprenes were studied. The splittings of signals were observed in the C₁, C₂, and C₄ carbon signals of the isomerized polyisoprenes. The newly appearing signals were assigned to the carbon atoms in cis-trans linkages. The fractions of the diad sequences (trans-trans, trans-cis, cis-trans, and cis-cis) were determined by using the four signals of C₁ carbon. It was found that the cis-1, 4- and trans-1, 4-units were randomly distributed in the isomerized polyisoprenes and it was confirmed that the chicle polyisoprene was a mixture of cis-1, 4- and trans-1, 4-polyisoprenes.     

Miscibility in binary blends of aromatic and alicyclic polyamides

Miscibility was studied for four polyamide blends of 6I/6T [copolymer consisting of 1,6‐hexamethylene diamine and isophthalic acid (6I) (70 wt %) and terephthalic acid (6T) (30 wt %)] with MXD6 (polyamide of m‐xylenediamine and adipic acid), BAC6 (polyamide of 1,3‐bis(aminomethyl)cyclohexane and adipic acid), TR55 (copolymer consisting of nylon 11 (30 wt %), and polyamide of bis(3‐methyl, 4‐aminocyclohexyl)methane (30 wt %) and isophthalic acid (70 wt %), and CX7323 (polyamide of bis(4‐aminocyclohexyl)methane and dodecanedicarboxylic acid), using differential scanning calorimetry, X‐ray diffraction method, and electronmicroscopic observation. In quenched MXD6/(6I/6T) and BAC6/(6I/6T) blends, MXD6 and BAC6 components were miscible to 6I/6T, but TR55 and CX7323 components were completely phase‐separated from 6I/6T. Interestingly on electronmicroscopic observations, TR55 and CX7323 components were seen as droplets in 6I/6T medium when the content is low, but when 50 wt %, a layered structure was constructed with 6I/6T, reminiscent of morphological structure in block copolymer. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3971–3978, 2006     

Ultra-high-precision time control system over any long time delay for laser pump and synchrotron x-ray probe experiment

An ultra-high-precision clock system for long time delay has been developed for picosecond time-resolved x-ray diffraction measurements using synchrotron radiation (SR) pulses and synchronized femtosecond laser pulses. The time delay control between pump laser pulse and the probe SR pulse was achieved by combining an in-phase quadrature modulator and a synchronous counter. This method allowed us to change the delay time by a nearly infinite amount while maintaining the precision of +/-8.40 ps. Time-resolved diffraction measurements using the delay control system were demonstrated for precise measurement of an acoustic velocity in a single crystal of gallium arsenide.     

Pilot-Scale Operation of a Concrete Sludge Recycling Plant and Simultaneous Production of Calcium Carbonate

A pilot-scale plant to treat concrete sludge and produce calcium carbonate (CaCO₃) and an environmental purification agent (phosphorus adsorbent derived from concrete sludge, PAdeCS®) was designed, constructed, and operated. Concrete sludge from a concrete pile and pole production plant, boiler gas containing CO₂, and groundwater were used in the plant. The process involved calcium extraction from concrete sludge into water, followed by reaction of the calcium with CO₂ to produce crystalline CaCO₃. The pilot-scale plant was operated for 1 week, and the mass flows, conversion of CO₂ to CaCO₃, and net CO₂ emissions of the process were estimated. High-purity CaCO₃ (>97%) suitable for industrial use was obtained. Based on the power consumption of the process and the amount of CO₂ sequestered into CaCO₃, a net reduction in CO₂ emissions can be achieved using this process. The produced PAdeCS can be used as an inexpensive substitute for calcium series environmental purification agents.     

A study on a porous residential building model in hot and humid regions: Part 1—the natural ventilation performance and the cooling load reduction effect of the building model

This study targets environmental load reduction in hot and humid regions. It reveals the effects that porous residential buildings have on the natural ventilation performance and, consequently, the cooling load reduction. Two residential building models, namely a model with a void ratio of 0% and a model with a void ratio of 50%, are evaluated using computational fluid dynamics (CFD) analysis and thermal and airflow network analysis. The analysis on components of the heat load indicates that improvements in the natural ventilation performance would significantly reduce the cooling load.     

A Two-Dimensional Analytical Solution for the Transient Short-Hot-Wire Method

Unlike the conventional transient hot-wire method for measuring thermal conductivity, the transient short-hot-wire method uses only one short thermal-conductivity cell. Until now, this method has depended on numerical solutions of the two-dimensional unsteady heat conduction equation to account for end effects. In order to provide an alternative and to confirm the validity of the numerical solutions, a two-dimensional analytical solution for unsteady-state heat conduction is derived using Laplace and finite Fourier transforms. An isothermal boundary condition is assumed for the end of the cell, where the hot wire connects to the supporting leads. The radial temperature gradient in the wire is neglected. A high-resolution finite-volume numerical solution is found to be in excellent agreement with the present analytical solution.     

In vivo monitoring of intravenously injected gold nanorods using near-infrared light

Gold nanorods showing surface plasmon (SP) bands in the near-IR region are used as bioimaging probes that respond to near-IR light in mice. The SP bands of intravenously injected polyethylene glycol-modified gold nanorods are directly monitored from the mouse abdomen by using a spectrophotometer equipped with an integrating sphere. The absorbance at 900 nm from the gold nanorods immediately increases after injection and reaches a plateau. The injection of phosphatidylcholine-modified gold nanorods also increases the absorbance at 900 nm, but the absorbance decreases single exponentially with a 1.3-min half-life. In vivo spectral changes of gold nanorods depend on the surface characteristics, and can be observed in real time using simple spectroscopic measurements.