Atomic disorders in layer structured topological insulator SnBi<Subscript>2</Subscript>Te<Subscript>4</Subscript> nanoplates

Identification of atomic disorders and their subsequent control has proven to be a key issue in predicting, understanding, and enhancing the properties of newly emerging topological insulator materials. Here, we demonstrate direct evidence of the cation antisites in single-crystal SnBi₂Te₄ nanoplates grown by chemical vapor deposition, through a combination of sub-ångström-resolution imaging, quantitative image simulations, and density functional theory calculations. The results of these combined techniques revealed a recognizable amount of cation antisites between Bi and Sn, and energetic calculations revealed that such cation antisites have a low formation energy. The impact of the cation antisites was also investigated by electronic structure calculations together with transport measurement. The topological surface properties of the nanoplates were further probed by angle-dependent magnetotransport, and from the results, we observed a two-dimensional weak antilocalization effect associated with surface carriers. Our approach provides a pathway to identify the antisite defects in ternary chalcogenides and the application potential of SnBi2Te4 nanostructures in next-generation electronic and spintronic devices.

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A Hemispherical Image Sensor Array Fabricated with Organic Photomemory Transistors

Hemispherical image sensors simplify lens designs, reduce optical aberrations, and improve image resolution for compact wide-field-of-view cameras. To achieve hemispherical image sensors, organic materials are promising candidates due to the following advantages: tunability of optoelectronic/spectral response and low-temperature low-cost processes. Here, a photolithographic process is developed to prepare a hemispherical image sensor array using organic thin film photomemory transistors with a density of 308 pixels per square centimeter. This design includes only one photomemory transistor as a single active pixel, in contrast to the conventional pixel architecture, consisting of select/readout/reset transistors and a photodiode. The organic photomemory transistor, comprising light-sensitive organic semiconductor and charge-trapping dielectric, is able to achieve a linear photoresponse (light intensity range, from 1 to 50 W m⁻²), along with a responsivity as high as 1.6 A W⁻¹ (wavelength = 465 nm) for a dark current of 0.24 A m⁻² (drain voltage = −1.5 V). These observed values represent the best responsivity for similar dark currents among all the reported hemispherical image sensor arrays to date. A transfer method was further developed that does not damage organic materials for hemispherical organic photomemory transistor arrays. These developed techniques are scalable and are amenable for other high-resolution 3D organic semiconductor devices.     

Localization of atrial natriuretic peptide receptors in the rat tongue and hard palate

The effect of a naturally occurring plant phenolic constituent (the acylphloroglucinol derivative, jensenone, derived from Eucalyptus jensenii) on the food intake of two folivorous marsupials, the common ringtail (Pseudocheirus peregrinus) and the common brushtail possum (Trichosurus vulpecula) was studied. When fed diets containing varying concentrations of jensenone, both species regulated their intake of jensenone so as not to exceed a ceiling intake. This ceiling was about twice as high for common ringtails as for common brushtails from northern Australia. Southern populations of common ringtails showed greatly reduced capacities to tolerate jensenone. When common brushtails were injected (0.5 mg.kg-0.75 body mass) with ondansetron (a selective antagonist of serotonin 5HT3 receptors), they ate significantly more jensenone than animals injected with physiological saline. The same pattern was observed when common ringtails were fed diets containing both jensenone and ondansetron (0.0035 mg.g-1 wet mass of diet). Ondansetron injection had no effect on food intake when the food did not contain jensenone while the addition of higher doses of ondansetron to diets of common ringtails very slightly reduced food intakes of a non-jensenone diet. When common brushtails were given 50 mg of jensenone by gastric lavage, their average subsequent intake of dietary jensenone matched the difference between the daily threshold and the dose given, although the response of individuals was highly variable. Lavage with water alone had no effect on subsequent jensenone intake compared with the pre-dose period. We interpret these results as evidence that the antifeedant effects of jensenone and related compounds are partly mediated by serotonin action on 5HT3 receptors most likely via "nausea" to condition a food aversion.     

Optical inhomogeneity and microstructure of ZrO(2) thin films prepared by ion-assisted deposition

The index inhomogeneity and the microstructure of ZrO(2) films prepared by Ar-ion-assisted deposition are investigated. The results show that as the Ar-ion momentum transferred to the growing film increases, the average refractive index increases, the vacuum-to-air spectral shift becomes almost zero, the sign of relative inhomogeneity transits from negative to positive, and the void fraction of the top layer next to air becomes smaller than that of the bottom one. These optical properties result from the improved packing density and denser outer region next to air. The Ar-ion bombardment also induces the changes in microstructure of ZrO(2) films, such as the preferential (111) orientation of cubic phase, increase in compressive stress, and reduction of surface roughness.     

Characterization of centrifugally atomized Al-12Si-5Fe-3Cu-1Mg(wt%) alloy powder and extruded rod

The Al-12Si-5Fe-3Cu-1Mg(wt%) alloy was rapidly solidified by centrifugal atomization. The microstructural characteristics of rapidly solidified powder and the microstructure changes with heat treatment were investigated in terms and related to powder size. The microstructures of the powder consisted of dendritic -Al, eutectic phase, Cu-rich phase, and needle-like intermetallic compounds. These phases were much finer than that of ingot cast structure and the size decreased with increasing cooling rate. The X-ray diffraction of the atomized powders revealed the presence of non-equilibrium 3-(AlFeSi) intermetallic phase. This phase appeared to transform to an equilibrium -(AlFeSi) phase by heating at temperatures above 470°C. The extruded rod which was hot extruded at 360°C with an extrusion ratio of 40:1 also revealed the presence of the -(AIFeSi) intermetallic phase. Using DSC, the exothermic peak due to precipitation from the supersaturated -Al matrix was observed in the range of 200–250°C during continuous heating of atomized powder, and the size of the peaks increased with decreasing powder size.     

Two‐phase trace‐driven simulation (TPTS): a fast multicore processor architecture simulation approach

Simulation is indispensable in computer architecture research. Researchers increasingly resort to detailed architecture simulators to identify performance bottlenecks, analyze interactions among different hardware and software components, and measure the impact of new design ideas on the system performance. However, the slow speed of conventional execution‐driven architecture simulators is a serious impediment to obtaining desirable research productivity. This paper describes a novel fast multicore processor architecture simulation framework called Two‐Phase Trace‐driven Simulation (TPTS), which splits detailed timing simulation into a trace generation phase and a trace simulation phase. Much of the simulation overhead caused by uninteresting architectural events is only incurred once during the cycle‐accurate simulation‐based trace generation phase and can be omitted in the repeated trace‐driven simulations. We report our experiences with tsim, an event‐driven multicore processor architecture simulator that models detailed memory hierarchy, interconnect, and coherence protocol based on the TPTS framework. By applying aggressive event filtering, tsim achieves an impressive simulation speed of 146 millions of simulated instructions per second, when running 16‐thread parallel applications. Copyright © 2010 John Wiley & Sons, Ltd.     

The Effectiveness of Short Message Service for Communication With Concerns of Privacy Protection and Conflict Avoidance

Why would people use Short Message Service (SMS) to say something they would not say in person? There is a trend that SMS is becoming more and more popular because it facilitates more extended modes of communications. Using technology acceptance model, we hypothesize the attitude of SMS would be influenced by its perceived effectiveness for communications, perceived ease of use, and subjective norm. Besides the special aspects of communications, conflict avoidance and privacy protection will enforce the impact of perceived effectiveness of SMS for communication. We investigated 953 SMS users and the results support most of our hypotheses. Furthermore, our analyses also show there are differences between females and males on the influence mechanism behind their attitude towards SMS.     

Buffer management in a real-time shared disks cluster

A great deal of research indicates that the shared disks (SD) cluster is suitable to high performance transaction processing. However, the aggregation of SD cluster with real-time processing has not been investigated. By adopting cluster technology, the real-time services will be highly available and can exploit internode parallelism. In this paper, we consider buffer management issues in a real-time SD cluster. We first propose a real-time buffer coherency algorithm that exploits inherent characteristics of real-time applications and SD cluster. Then we extend traditional buffer replacement algorithms to the real-time SD cluster. They emphasize specific attributes of buffer pages to capitalize locality of references, transaction deadline, and affinity-based routing. We evaluate the performance of the proposed algorithms under a wide variety of transaction workloads and system configurations.