Mechanisms of plastic deformation of zirconium-based alloys upon uniaxial compression under different temperature-rate conditions

Based on the results of X-ray diffraction analysis of texture of the Zr-1% Nb and Zr-2.5% Nb model alloys compressed uniaxially at temperature corresponding to the β and α + β fields of the phase diagram, the mechanisms responsible for plastic deformation have been determined. These are the crystallographic slip in the β-Zr and α-Zr grains and also the diffusional mechanism of mutual displacement of crystallites along interphase boundaries, which is activated upon the α ? β phase transformations and is the basis of superplasticity. The contribution of each mechanism to the formation of specimen texture depends on the temperature-rate regime of compression.     

One-step route to a hybrid TiO2/TixW1?xN nanocomposite by in situ selective carbothermal nitridation

Metal oxide/nitride nanocomposites have many existing and potential applications, e.g. in energy conversion or ammonia synthesis. Here, a hybrid oxide/nitride nanocomposite (anatase/Ti_xW_1−xN) was synthesized by an ammonia-free sol–gel route. Synchrotron x-ray diffraction, complemented with electron microscopy and thermogravimetric analysis, was used to study the structure, composition and mechanism of formation of the nanocomposite. The nanocomposite contained nanoparticles (<5 nm diameter) of two highly intermixed phases. This was found to arise from controlled nucleation and growth of a single oxide intermediate from the gel precursor, followed by phase separation and in situ selective carbothermal nitridation. Depending on the preparation conditions, the composition varied from anatase/Ti_xW_1−xN at low W content to an isostructural mixture of Ti-rich and W-rich Ti_xW_1−xN at high W content. In situ selective carbothermal nitridation offers a facile route to the synthesis of nitride-oxide nanocomposites. This conceptually new approach is a significant advance from previous methods, which generally require ammonolysis of a pre-synthesized oxide.     

Consumer Selection of E-Commerce Websites in a B2C Environment: A Discrete Decision Choice Model

Despite the suggestions of friction-free information availability, considerable price dispersions for the same product are not uncommon across online retailers in the business-to-consumer (B2C) segment. Online customers do not necessarily always buy from the site with the lowest price, suggesting that other forces are at work. This paper presents and empirically examines a model that proposes that Web site value in terms of (perceived) Web site quality as well as awareness of the site and consumer differences (on price sensitivity) are key variables in explaining online consumer behavior in their choice of Web site despite the existence of price dispersions. Two hundred ninety-three students participated in a series of controlled laboratory experiments making use of two different types of products in terms of complexity and expensiveness (Canon digital camera Powershot S400 and digital versatile disc full-screen edition of Star Wars: Episodes I and II) that required them to interact with three different real-world Web sites offering each of these two branded products and make their decision on which of the three Web sites they will chose to buy the product from. The prices varied across the Web sites, as did the quality of the sites on various dimensions and site awareness of the participants. Conditional logit models of discrete choice for each of the two product types indicate differential influences of Web site quality dimensions and price sensitivity. A number of interesting implications emerge, and pointers to further extensions of the research theme are discussed.     

Recruitment of low threshold motor-units in the trapezius muscle in different static arm positions

A prevailing hypothesis for development of myalgia symptoms in the trapezius muscle is based on observations that in stereotypic activation of muscle the same low-threshold motor-units are the first ones to be recruited, and that these units are active throughout the contraction, until total relaxation. The theory suggests that these units are the first ones in monotonous repetitive work to be subject to degenerative processes, causing pain. The present project was undertaken to evaluate to what extent recruitment of motor-units in the trapezius muscle is position-specific, i.e. if there are motor-units that are recruited over a wide range of arm postures. Fine wire electrode pairs, inserted 2 cm lateral to the midpoint between the acromion and the C7 spinous processus, were used for signal acquisition. Methods for decomposition of the interference patterns were developed, allowing identification of single motor-units in signals registered in different arm positions. Voluntary recruitment of motor-units in the descending portion of the trapezius muscle was studied in 24 different arm positions (0-90 degrees shoulder flexion, 0-45 degrees humeral abduction, and 45-135 degrees elbow flexion) in three subjects. The results showed that the wire electrode technique and the signal processing algorithm employed allowed motor-unit identification in non-isometric conditions. It was found that low threshold motor-units in the trapezius muscle, active over a wide range of arm positions, could be identified in all three subjects. We refer to those as Cinderella, or C, units. These results support the research hypothesis addressed.     

Impact of Cooperative R&D Projects on ICT‐Based Technology Convergence

This study examines how the characteristics of cooperative research and development (R&D) projects in the public domain impact information and communication technology (ICT) convergence. Based on the analysis of 416 cooperative R&D projects under the ICT‐based industry convergence R&D program in Korea, the study finds that the characteristics of cooperative R&D projects significantly impact ICT convergence. Moreover, the participation of public research institutes and universities is critical for ICT convergence compared with that of firms. However, in firm‐to‐firm cooperation, the participation of small and medium enterprises contributes to cross‐sectional convergence, while the participation of large firms leads to overall and longitudinal convergence. R&D inputs such as the number of partners and government subsidies exhibit an inverted U‐shaped relationship (negative quadratic effect) with technology convergence. Project duration and homogeneous partners are also critical factors for ICT convergence. The results indicate several implications and guidelines on how to effectively organize cooperative R&D projects to facilitate technology convergence.     

Understanding the Potential In Vitro Modes of Action of Bis(β-diketonato) Oxovanadium(IV) Complexes

To understand the potential in vitro modes of action of bis(β-diketonato) oxovanadium(IV) complexes, nine compounds of varying functionality have been screened using a range of biological techniques. The antiproliferative activity against a range of cancerous and normal cell lines has been determined, and show these complexes are particularly sensitive against the lung carcinoma cell line, A549. Annexin V (apoptosis) and Caspase-3/7 assays were studied to confirm these complexes induce programmed cell death. While gel electrophoresis was used to determine DNA cleavage activity and production of reactive oxygen species (ROS), the Comet assay was used to determine induced genomic DNA damage. Additionally, Förster resonance energy transfer (FRET)-based DNA melting and fluorescent intercalation displacement assays have been used to determine the interaction of the complexes with double strand (DS) DNA and to establish preferential DNA base-pair binding (AT versus GC).     

Triple-Networked Hybrid Hydrogels Reinforced with Montmorillonite Clay and Graphene Nanoplatelets for Soft and Hard Tissue Regeneration

Hydrogel is a three-dimensional (3D) soft and highly hydrophilic, polymeric network that can swell in water and imbibe a high amount of water or biological fluids. Hydrogels have been used widely in various biomedical applications. Hydrogel may provide a fluidic tissue-like 3D microenvironment by maintaining the original network for tissue engineering. However, their low mechanical performances limit their broad applicability in various functional tissues. This property causes substantial challenges in designing and preparing strong hydrogel networks. Therefore, we report the triple-networked hybrid hydrogel network with enhanced mechanical properties by incorporating dual-crosslinking and nanofillers (e.g., montmorillonite (MMT), graphene nanoplatelets (GNPs)). In this study, we prepared hybrid hydrogels composed of polyacrylamide, poly (vinyl alcohol), sodium alginate, MMT, and MMT/GNPs through dynamic crosslinking. The freeze-dried hybrid hydrogels showed good 3D porous architecture. The results exhibited a magnificent porous structure, interconnected pore-network surface morphology, enhanced mechanical properties, and cellular activity of hybrid hydrogels.     

Multi‐criteria Evaluation of Mobile Network Sharing Policies in Korea

Mobile operators in saturated markets increasingly favor mobile network sharing (MNS) over facility‐based competition. Previous research examining MNS primarily focused on its positive effects, while the negative effects were largely overlooked. This study proposes a decision‐making model using an analytic hierarchy process technique to evaluate decision‐making criteria among various types of MNS policies. The decision‐making model was applied to Wireless Broadband services in Korea to determine the relative importance of both positive and negative evaluation criteria and preference among multiple types of MNS policies. Positive evaluation criteria (that is, efficiency) were far greater in importance than negative evaluation criteria (that is, competition harm). The preference for adopting MNS among five alternative approaches was also revealed. The study findings offer immediate policy insights in Korea and provide a decision‐making framework for policy makers in other countries to utilize.