Anisotropic strains, metal-insulator transition, and magnetoresistance of La0.7_{0.7}Ca0.3_{0.3}MnO3_{3} films

Thin films of perovskite manganite La$_{0.7}$Ca$_{0.3}$MnO$_{3}$ were grown epitaxially on various substrates by either the pulsed laser deposition method or laser molecular beam epitaxy. The substrates change both the volume and symmetry of the unit cell of the films. It is revealed that the symmetry as well as the volume of the unit cell have strong influence on the metal-insulator transition temperature and the size of magnetoresistance.Comment: 6 pages, 3 figure

Chemical Profiling of the Aerial Parts and Roots of Ixeris dentata Using LCQTOF-MS Combined with Multivariate Chemometric Analysis

Ixeris dentata (Thunb. ex Thunb.) Nakai (Asteraceae) is a perennial herb distributed throughout East Asia including Korea, China and Japan. Both its aerial parts and roots are edible as a bitter appetizing vegetable. In addition, they have been used in folk medicine for the treatment of various diseases. In the present study, the chemical profiles of the aerial parts and roots of I. dentata were investigated using HPLC-QTOF-MS combined with multivariate chemometric analysis. From 18 samples collected in 7 different areas, 30 compounds were characterized and most of them were sesquiterpenes and flavonoids. Principal component analysis of them clearly distinguished the samples of I. dentata by the parts, aerial parts and roots. The loading plots gave the information about the important compounds responsible for the discrimination between plant parts. Hierarchical cluster analysis also showed clear distinction between two parts. Although I. dentata samples derived from the same plant, there was difference in their chemical profiles, which might account for their different use

The digital divide in Education and students' home use of ICT

The Conference proceedings' website is located at http://conference.pixel-online.net/edu_future2012/acceptedabstracts.phpThe digital divide is a widely acknowledged global problem in the information age. The Hong Kong Government has recently launched a five-year “i Learn at home” program in 2011 to assist students from low-income families to purchase computers and pay for broadband services so that they can learn through the Internet at home. However, more recent discourses increasingly argue that the digital divide is not only about availability of networks and gadgets, but also about having or not having information. It calls for a refocus of the problem of the digital divide from a mere availability of computers and Internet network access to high order information literacy skills and education. Numerous studies indicate that the digital divide is a complex and dynamic phenomenon and the issue has been examined from a broader perspective. Given the many thousands of books and studies that have been dedicated to exploring the promises and potential of using information and communication technology (ICT) in education, the issue of the digital divide in this context deserves special attention. Students are now living with a sophisticated range of new and rapidly changing ICT tools. Thus, the digital divide in education, as an ongoing concern, should not be constructed only as an issue of technical or resource support. Unpacking the social, cultural and contextual dynamics of how students use ICT in and outside school, particularly home use of ICT, is important. This paper presents findings of a survey of 468 junior secondary students in Hong Kong. In the survey questionnaire, students were asked to report their ICT use in and outside school and perception on various issues related to contextual and family factors. The results of regression analysis indicate that students’ use ICT for learning or entertainment at home are significantly related to the variables of students’ use of ICT in school, students’ Internet literacy, formation of family rules, using ICT in public areas, parental permission, and parental monitoring. The results, obtained by means of ANOVA model, indicate that the variables of parents’ education have effect on the variables of students’ use of ICT in school, students’ Internet literacy, family cohesion, and parental participation and encouragement in students’ ICT use at home. Implications to the issues of digital divide in education are discussed. The study presented in this paper is a part of a Public Policy Research project entitled “Educational Inequality and ICT Use in Schools: Bridging the Digital Divide” funded by the Research Grants Council.published_or_final_versio

Nanoscale Prediction of Graphite Surface Erosion by Highly Energetic Gas - Molecular Dynamics Simulation -

This paper was presented at the 4th Micro and Nano Flows Conference (MNF2014), which was held at University College, London, UK. The conference was organised by Brunel University and supported by the Italian Union of Thermofluiddynamics, IPEM, the Process Intensification Network, the Institution of Mechanical Engineers, the Heat Transfer Society, HEXAG - the Heat Exchange Action Group, and the Energy Institute, ASME Press, LCN London Centre for Nanotechnology, UCL University College London, UCL Engineering, the International NanoScience Community, www.nanopaprika.eu.In order to understand the fundamental essence in the erosion of graphite by hot gas molecules, in this study we investigate the mechanical properties of a single layer of graphite (e.g. graphene) and the bombardment of CO2 and H2O on graphene at high temperature by using extensive molecular dynamics (MD) simulations. The Reactive Empirical Bond Order (REBO) potential is employed to model the C-C bonds. The stress-strain curve shows that the stiffness of graphene decreases with increase in temperature. The strength of graphene at 2400 K is 60% less than the strength of graphene at 300 K. Also, we observe that the collision with CO2 and H2O provokes the bond breaking of C-C bonds in graphene at high temperature. The bombardment of gas molecules is carried out for different temperatures ranging between 300 K and 3000 K. Until 2400 K, both H2O and CO2 molecules are reflected back from the surface. However, at a critical temperature i.e., 2700 K and beyond, the bombardment of gas molecules breaks the C-C bond in the graphene. As the temperature increases, the graphene is destroyed quickly. This study shows that even the real gas molecules can induce the fracture of graphene at high temperature

Temperature distribution in the force-driven poiseuille gas flow by molecular dynamics

This paper was presented at the 4th Micro and Nano Flows Conference (MNF2014), which was held at University College, London, UK. The conference was organised by Brunel University and supported by the Italian Union of Thermofluiddynamics, IPEM, the Process Intensification Network, the Institution of Mechanical Engineers, the Heat Transfer Society, HEXAG - the Heat Exchange Action Group, and the Energy Institute, ASME Press, LCN London Centre for Nanotechnology, UCL University College London, UCL Engineering, the International NanoScience Community, www.nanopaprika.eu.The thermal behavior of the force-driven compressible Poiseuille gas flow is studied by molecular dynamics (MD) simulation method. This type of flow situation occurs in the cooling system of MEMS/NEMS devices and hence the properties of Poiseuille gas flow become significant, especially the thermal behavior. The peculiar behavior of the force-driven Poiseuille gas flow, local minimum at the center in the temperature profile, is investigated in detail. Emphasis is placed on variations of the temperature distribution for different Knudsen numbers. Previously, the central temperature minimum and other flow peculiarities have been described by a non-classical non-Fourier theory based on nonlinear coupled constitutive relations. The main goal of this study is to investigate the thermal behavior of the force-driven Poiseuille gas flow using molecular dynamics simulations and to compare the results with that of non-classical non-Fourier theory. The MD results in general show agreement with the data from the non-classical hydrodynamic theory, which confirms the validity of MD method in analyzing the micro/nano gas flows including thermal behaviors

Effect of additives on the viscosity of liquid-phase dimethylaluminum hydride

The effect of additives on the viscosity of liquid-phase dimethylaluminum hydride (DMAH) was investigated. The viscosity of pure liquid DMAH was measured to be 6400 centipoise (cP) and due to its high viscosity, it is difficult to vaporize DMAH effectively in a bubbler in the chemical vapor deposition of aluminum. N,N-Dimethyl-1-naphthylamine and N-ethyl-N-methylaniline were selected as an additive because they are a liquid at room temperature and have a high boiling point. The viscosity of DMAH was drastically reduced down to 6 cP with the addition of 3.2 mol % of N-ethyl-N-methylaniline and 8 cP with the addition of 4.3 mol % of N,N-dimethyl-1-naphthylamine.ope

Similarities in Dielectrophoretic and Electrophoretic Trap

This paper was presented at the 4th Micro and Nano Flows Conference (MNF2014), which was held at University College, London, UK. The conference was organised by Brunel University and supported by the Italian Union of Thermofluiddynamics, IPEM, the Process Intensification Network, the Institution of Mechanical Engineers, the Heat Transfer Society, HEXAG - the Heat Exchange Action Group, and the Energy Institute, ASME Press, LCN London Centre for Nanotechnology, UCL University College London, UCL Engineering, the International NanoScience Community, www.nanopaprika.eu.In this study we present a universal theoretical formulation of the particle motions in electrophoretic and dielectrophoretic traps. It is extended from the well-known Mathieu equation based theories for Paul trap. The white noise random force model is utilized to form the Brownian motion of particle in the traps and the instantaneous dielectrophoretic force is employed rather than the time-averaged ponderomotive expression. The new approach enables many interesting properties of dielectrophoretic traps about stability and random motion. This study will be expected to provide a concrete protocol for the design of nanoscale traps which is essential in single molecule analysis

Impact crashworthiness of a floating offshore nuclear power plant hull structure in a terrorist attack with an aircraft strike

The aim of this study is to investigate the impact crashworthiness of a floating offshore nuclear power plant hull structure in an aircraft strike; the hull has a double-sided design that includes ballasting with either sand or concrete. As a hazardous event associated with a terrorist attack, one of the unfavourable impact scenarios is adopted in which a Boeing 777 airplane strikes the hull structure at a full speed. This study examines the contribution of ballasting materials such as sand or concrete to the penetration of the striking body into the hull structure in an aircraft strike as the power plant is gravity based sitting on the seabed. The LS-DYNA nonlinear finite-element method is employed for the structural crashworthiness analysis. Details of the computational modelling and resulting insights are documented

Alloy Design to Prevent Intergranular Corrosion of Low-Cr Ferritic Stainless Steel with Weak Carbide Formers

Effect of weak carbide formers, Mo, Mn and Si, on intergranular corrosion (IGC) of low-Cr ferritic stainless steel is analyzed after IGC test using TEM and three dimensional atom probe. The co-addition ofMo, Mn and Si to low-Cr ferritic stainless steel effectively prevents IGC by forming along grain boundaries CMn4MoSi intermetallic compounds, which act not only as carbon trap sites but also as diffusion barrier against solute Cr diffusion toward grain boundaries. The low solubility of Cr in the CMn4MoSi intermetallic compound results in replenishing Cr in the Cr-depleted area. (C) The Author(s) 2015. Published by ECS. All rights reserved.114Ysciescopu