Synthesis of Ti5Si3-x Nb composites by the field-activated combustion method

The influence of an electric field on the combustion synthesis of Ti₅Si₃-x Nb composites (0≤ x ≤0.8) was investigated. Composites where x ≥ 0.8 can only be synthesized in the presence of a field. In the absence of a field, those systems where x=0.8 can result in a non-steady combustion wave causing an incomplete reaction. That is, an unstable wave propagates to the middle of the sample and then becomes extinguished. The wave velocity of the Ti₅Si₃-x Nb composites slightly increases with the imposition of an external electric field across the sample.     

Biomimetic micropatterning of silica by surface-initiated polymerization and microcontact printing

Micropatterns of silica on a gold substrate were generated by a biomimetic approach, namely, the biosilicification of silicic acids. The procedure consists of three simple steps: pattern generation of a polymerization initiator, (BrC(CH(3))(2)COO(CH(2))(11)S)(2), by microcontact printing; surface-initiated, atom-transfer radical polymerization of 2-(dimethylamino)ethyl methacrylate (DMAEMA) from the patterned area; and polycondensation of silicic acids. The tertiary amine-containing polymer, pDMAEMA, aided in the spatially controlled polycondensation of silicic acids on surfaces in the presence of phosphate ions, and micropatterns of silica on a gold substrate were successfully generated in combination with the technique of microcontact printing. The procedure could be extended to the controlled fabrication of silica patterns with any size, shape, or thickness.     

Toward Advanced Mobile Cloud Computing for the Internet of Things: Current Issues and Future Direction

Cloud computing is the coming new era of information processing and has proved its benefits in high scalability and functional diversity. However, almost all cloud-computing architectures including SaaS, PaaS, and IaaS are vulnerable to serious security issues. Similarly, Mobile Cloud Computing (MCC) is vital to overcoming mobile limited storage and computing capabilities. MCC authentication and authorization issues must be provided on two levels: login password control and the environment from where the cloud is accessed. MCC has overcome the barrier of limited storage by providing remote storage but requires a strict security system that is responsible for retrievability, integrity, and seamless storage access. Elasticity and connectivity are also of major concern in MCC because delays and jitters cause degradation in the user experience. Cloud-computing architecture creates more challenges in maintaining security because of the liberty of users to choose any MCC architecture. Thus in this paper we discuss current cloud computing issues and future directions.     

Physicochemical and Gelatinization Properties of Starches Separated from Various Rice Cultivars

Morphological, viscoelastic, hydration, pasting, and thermal properties of starches separated from 10 different rice cultivars were investigated. Upon gelatinization, the G′ values of the rice starch pastes ranged from 37.4 to 2057 Pa at 25 °C, and remarkably, the magnitude depended on the starch varieties. The rheological behavior during gelatinization upon heating brought out differences in onset in G′ and degree of steepness. The cultivar with high amylose content (Goami) showed the lowest critical strain (γ_c), whereas the cultivars with low amylose content (Boseokchal and Shinseonchal) possessed the highest γ_c. The amylose content in rice starches affected their pasting properties; the sample possessing the highest amylose content showed the highest final viscosity and setback value, whereas waxy starch samples displayed low final viscosity and setback value. The onset gelatinization temperatures of the starches from 10 rice cultivars ranged between 57.9 and 64.4 °C. The amylose content was fairly correlated to hydration and pasting properties of rice starches but did not correlate well with viscoelastic and thermal characteristics. The combined analysis of hydration, pasting, viscoelastic, and thermal data of the rice starches is useful in fully understanding their behavior and in addressing the processability for food applications.     

Fabrication and characterization of a Ni-YSZ anode support using high-frequency induction heated sintering (HFIHS)

Ni-YSZ cermet anode supports solid oxide fuel cells (SOFCs) were fabricated by high-frequency induction heated sintering (HFIHS) under 60 MPa pressure with powders synthesized by the glycine nitrate process (GNP) as well as mechanically mixed commercial powders. The HFIHS method created a uniformly porous microstructure without abnormal grain growth compared to the conventional sintering method. Samples sintered by HFIHS show higher strength and electrical conductivity than conventionally sintered samples, even though they have similar porosity.     

Analysis of fracture mechanisms of ultrathin glass for flexible cover window under pen drop conditions

The fracture mechanism of a chemically strengthened ultrathin glass (UTG) for the cover window of flexible display devices was investigated under pen loading conditions for the first time to better understand the UTG impact resistance characteristics. High-speed camera analysis, fracture fragment analysis, and finite element modeling were employed to investigate the fracture mechanism of the UTG under pen drop conditions. A pen-on-plate (POP) test was also employed to examine the fracture characteristics under static loading condition, and its results were compared with those of the pen drop test (PDT) to find a correlation between the static and dynamic loading conditions. The correlation found between the POP and PDT tests indicates that a quantitative estimation of contact displacement under PDT can be obtained by measuring the first ring crack size, to more easily determine the impact resistance characteristics of UTG.     

Effect of Fe2O3 addition on consolidation and properties of 8 mol% yttria-stabilized zirconia by high-frequency induction heated sintering (HFIHS)

Dense nanophase 8 mol% yttria-stabilized zirconia was sintered by high-frequency induction heated sintering (HFIHS) within 6 min from 8YSZ nanopowder prepared by co-precipitation method. Sintering was accomplished under the combined effects of an induced current and mechanical pressure. Highly dense 8YSZ with relative density of up to 96% was produced under simultaneous application of a 60-MPa pressure and the induced current. The effects of Fe₂O₃ additions on the sintering behavior, mechanical properties and ionic conductivities of the 8YSZ were investigated.