440 research outputs found

    Book reviews

    Get PDF
    Teaching/Communication/Extension/Profession,

    Uptake and Diffusion of Ions in Organically Synthesized Porous Carbon for Battery Anode Applications

    Get PDF
    Organically synthesized porous carbon (OSPC-1) has a high lithium uptake of 748 mA h g-1, demonstrating that it is a strong contender as an anode material for lithium-ion batteries. Simulations of the lithium uptake on models generated of OSPC-1 gave values close to the experimentally obtained data. Thus, we assess the potential of OSPC-1 for use as an anode material in batteries of sodium, potassium, magnesium, and calcium. We find ion uptakes of 770, 386, 158, and 774 mA h g-1 for Li+, Na+, K+, and Ca2+, respectively. We also study the diffusive capabilities of ions through the OSPC-1 structure via means of active diffusion. The lithium ions were able to diffuse at a greater rate, followed by the divalent ions, Mg2+ and Ca2+, and the monovalent ions, Na+ and K+. All these ions were able to diffuse completely through the OSPC-1 structure with the diffusion rate being dependent on the ionic radius of the ion, coupled with the valency of the ion. Therefore, we show that OSPC-1 also has great potential as an anode material for Na+, K+, Mg2+, and Ca2+ batteries

    Services diagnostic and needs assessment study

    Get PDF
    Liberalisation of trade in services and associated domestic reforms is fundamental to the realisation of the ASEAN Economic Community (AEC). However, this requires real (‘on the ground’) liberalisation, not simply “on paper” liberalisation in the form of commitments under the ASEAN Framework Agreement on Services (AFAS), a sideshow in services liberalisation. The decision by leaders to form an AEC covering also the free flow of services has put the emphasis very much on ensuring each ASEAN Member State (AMS) removes restrictions affecting trade in services (including related foreign investment) and implement related reforms. However, the diagnostic analysis presented in this Services Diagnostic and Needs Assessment Study (SDNAS), including in the in-country reports, suggests this is not happening, or at least is going very slowly, especially when set against the adopted start date for the AEC of 2015. Hence, key and effective technical assistance and capacity building is needed to advance ‘on the ground’ liberalisation of services and related reforms. The in-country fieldwork and other analysis undertaken in the SDNAS helped identify constraints and provided a list of potential technical assistance and capacity building projects to help address them, both from a primarily cross-cutting but also a sectoral perspective. The SDNAS has also adopted an economic framework based on the fundamental benefits of unilateral liberalisation and a strategic structured approach, to identify key areas (‘umbrellas’) needing technical assistance and capacity building activities, such as strengthening the evidence base, promoting transparency, developing strategies and planning, and raising understanding and awareness. Key activity clusters were also identified within these three ‘umbrellas’, such as policy analysis, services policy visions, and organisations for dialogues, respectively. Individual priority technical assistance and capacity building project proposals within these clusters were determined using a cost-benefit analytical approach. The SNDAS importantly recommends the need to re-balance much of the technical assistance and capacity building activities away from being directed at servicing the AFAS trade negotiations and focusing on ‘on-paper’ liberalisation towards efforts to build transparency and fundamental support for services trade liberalisation and related reforms in AMS. This is what is required to achieve the necessary ‘on-the-ground’ changes to achieve the AEC. This is consistent with international experience that significant ‘on-the-ground’ services liberalisation and related reforms requires unilateral efforts, and that trade negotiations have generally failed to deliver such changes. With this in mind, the SNDAS has developed and recommended a number of detailed proposed technical assistance and capacity building project templates

    Design and characterization of AmLi neutron sources for the LZ experiment

    Full text link
    In this paper we describe the development, testing, and characterization of three low-emission rate AmLi neutron sources. The sources are used to calibrate the nuclear recoil response of the LUX-ZEPLIN (LZ) dark matter experiment. The sources' neutron emission rate was measured using 3^{3}He proportional tubes. The sources' gamma emissions were characterized using a high-purity germanium (HPGe) detector. Source-validated GEANT4 Monte Carlo simulations allowed to calibrate the Ge and neutron detector responses.Comment: 20 pages, 13 figures, 4 tables, revised manuscripts after accommodating the reviewer's comment

    Conceivable security risks and authentication techniques for smart devices

    Get PDF
    With the rapidly escalating use of smart devices and fraudulent transaction of users’ data from their devices, efficient and reliable techniques for authentication of the smart devices have become an obligatory issue. This paper reviews the security risks for mobile devices and studies several authentication techniques available for smart devices. The results from field studies enable a comparative evaluation of user-preferred authentication mechanisms and their opinions about reliability, biometric authentication and visual authentication techniques

    Artificial Synthesis of Conjugated Microporous Polymers via Sonogashira-Hagihara Coupling

    Get PDF
    Amorphous network materials are becoming increasingly important with applications, for example, as supercapacitors, battery anodes, and proton conduction membranes. The design of these materials is hampered by the amorphous nature of the structure and sensitivity to synthetic conditions. Here, we show that through artificial synthesis, fully mimicking the catalytic formation cycle, and full synthetic conditions, we can generate structural models that can fully describe the physical properties of these amorphous network materials. This opens up pathways for the rational design where complex structural influences, such as the solvent and catalyst choice, can be taken into account

    Modular and predictable assembly of porous organic molecular crystals

    No full text
    Nanoporous molecular frameworks are important in applications such as separation, storage and catalysis. Empirical rules exist for their assembly but it is still challenging to place and segregate functionality in three-dimensional porous solids in a predictable way. Indeed, recent studies of mixed crystalline frameworks suggest a preference for the statistical distribution of functionalities throughout the pores rather than, for example, the functional group localization found in the reactive sites of enzymes. This is a potential limitation for 'one-pot' chemical syntheses of porous frameworks from simple starting materials. An alternative strategy is to prepare porous solids from synthetically preorganized molecular pores. In principle, functional organic pore modules could be covalently prefabricated and then assembled to produce materials with specific properties. However, this vision of mix-and-match assembly is far from being realized, not least because of the challenge in reliably predicting three-dimensional structures for molecular crystals, which lack the strong directional bonding found in networks. Here we show that highly porous crystalline solids can be produced by mixing different organic cage modules that self-assemble by means of chiral recognition. The structures of the resulting materials can be predicted computationally, allowing in silico materials design strategies. The constituent pore modules are synthesized in high yields on gram scales in a one-step reaction. Assembly of the porous co-crystals is as simple as combining the modules in solution and removing the solvent. In some cases, the chiral recognition between modules can be exploited to produce porous organic nanoparticles. We show that the method is valid for four different cage modules and can in principle be generalized in a computationally predictable manner based on a lock-and-key assembly between modules

    WMO Assessment of Weather and Climate Mortality Extremes: Lightning, Tropical Cyclones, Tornadoes, and Hail

    Get PDF
    A World Meteorological Organization (WMO) Commission for Climatology international panel was convened to examine and assess the available evidence associated with five weather-related mortality extremes: 1) lightning (indirect), 2) lightning (direct), 3) tropical cyclones, 4) tornadoes, and 5) hail. After recommending for acceptance of only events after 1873 (the formation of the predecessor of the WMO), the committee evaluated and accepted the following mortality extremes: 1) “highest mortality (indirect strike) associated with lightning” as the 469 people killed in a lightning-caused oil tank fire in Dronka, Egypt, on 2 November 1994; 2) “highest mortality directly associated with a single lightning flash” as the lightning flash that killed 21 people in a hut in Manica Tribal Trust Lands, Zimbabwe (at time of incident, eastern Rhodesia), on 23 December 1975; 3) “highest mortality associated with a tropical cyclone” as the Bangladesh (at time of incident, East Pakistan) cyclone of 12–13 November 1970 with an estimated death toll of 300 000 people; 4) “highest mortality associated with a tornado” as the 26 April 1989 tornado that destroyed the Manikganj district, Bangladesh, with an estimated death toll of 1300 individuals; and 5) “highest mortality associated with a hailstorm” as the storm occurring near Moradabad, India, on 30 April 1888 that killed 246 people. These mortality extremes serve to further atmospheric science by giving baseline mortality values for comparison to future weather-related catastrophes and also allow for adjudication of new meteorological information as it becomes available

    A theoretical model to elucidate the elusive concept ‘voice' for interpreters

    Get PDF
    This paper is an attempt to elucidate the concept of voice for interpreters in relation to the equally elusive concept pleasant voice for interpreters. The point of departure is that the concept voice for interpreting has to do with the physical properties of a speaker’s voice, which may lead to the effect that a speaker’s voice is heard as pleasant or unpleasant by a listener, depending on how a speaker uses or deploys these physical properties. The paper employs an interdisciplinary approach to reviewing relevant literature and shows that for better interpreter education and interpreting assessment, there is a need to unravel, and unify existing understandings of the concept voice. A new definition is therefore proposed. The new definition consists of a cluster of suprasegmental features resulted from supralaryngeal and laryngeal activities and incorporates in what are traditionally known as fluency features in interpreting. The paper goes on to discuss the potential benefits and implications of the newly proposed definition for both interpreter training and interpreting studies
    • 

    corecore