Aggregation of a dibenzo[b,def]chrysene based organic photovoltaic material in solution

Detailed electrochemical studies have been undertaken on molecular aggregation of the organic semiconductor 7,14-bis((triisopropylsilyl)-ethynyl) dibenzo[b,def]chrysene (TIPS-DBC), which is used as an electron donor material in organic solar cells. Intermolecular association of neutral TIPS-DBC molecules was established by using 1H NMR spectroscopy as well as by the pronounced dependence of the color of TIPS-DBC solutions on concentration. Diffusion limited current data provided by near steady-state voltammetry also reveal aggregation. Furthermore, variation of concentration produces large changes in shapes of transient DC and Fourier transformed AC (FTAC) voltammograms for oxidation of TIPS-DBC in dichloromethane. Subtle effects of molecular aggregation on the reduction of TIPS-DBC are also revealed by the highly sensitive FTAC voltammetric method. Simulations of FTAC voltammetric data provide estimates of the kinetic and thermodynamic parameters associated with oxidation and reduction of TIPS-DBC. Significantly, aggregation of TIPS-DBC facilitates both one-electron oxidation and reduction by shifting the reversible potentials to less and more positive values, respectively. EPR spectroscopy is used to establish the identity of one-electron oxidized and reduced forms of TIPS-DBC. Implications of molecular aggregation on the HOMO energy level in solution are considered with respect to efficiency of organic photovoltaic devices utilizing TIPS-DBC as an electron donor material. © 2014 American Chemical Society.

Norm diffusion within international organizations: a case study of the World Bank

Constructivists often argue that International Organizations (IOs) diffuse norms throughout the international system. This article asks the question: if IOs promote and diffuse specific norms within world politics, where do these norms come from? In particular, this analysis seeks to formulate how IOs' identities emerge in issue areas where rationalist theories give limited explanation, such as the environment. This article posits that IOs interact with and consume norms from non-state actors such as transnational advocacy networks, a process overlooked by the constructivist analysis of institutions. This is examined through a case study of the World Bank's environmental identity where transnational advocacy networks played an important role in the Bank's shift towards sustainable development, through processes characterized here as direct and indirect socialization. This article demonstrates that the Bank's shift was more than instrumental as a result of this interaction, and that constructivists therefore need to examine the role of IOs as norm consumers as well as norm diffusers.

Ion diffusion in molten salt mixtures

The molten salts, 1-methyl,3-ethylimidazolium trifluoromethanesulfonate (triflate salt, MeEtImTf) and 1-methyl,3-ethylimidazolium bis(trifluoromethanesulfonimide) (imide salt, MeEtImNTf₂) are colourless ionic liquids with conductivities of the order of 10⁻² S cm⁻¹ at room temperature. DSC measurements revealed subambient melting and glass transition temperatures. Analysis of the anion and cation diffusion coefficients suggested that the cation was the dominant charge carrier and that the motion was largely independent of the anion. Haven ratios (H_Rs) of 1 and 1.6 were determined for the imide and triflate salts, respectively, at 30°C (303 K). Values greater than one imply some degree of ionic association, suggesting that aggregation is present in the triflate salt. Mixing of the salts to form binary systems resulted in enhanced conductivities which deviated from a simple law of mixtures. Thermal analysis showed no evidence of a melting point with only a glass transition observed. Corresponding diffusion measurements for the binaries appeared to show a weighted average of the diffusion coefficients of the pure components. The increased conductivity can be attributed to an increase in the number of charge carriers as a result of decreased ion association in the binary.

Aggregation, ageing and transport properties of surface modified fumed silica dispersions

We have investigated the aggregation, ageing and transport properties of surface modified silica dispersions in DMSO by photon correlation spectroscopy and conductivity measurements. The surface modification introduces Li+-ions that dissociate in the dispersion creating a single Li+-ion conducting electrolyte. We show that the surface modification changes the aggregation and ageing properties of the material. There is a pronounced ageing observed for the modified silica dispersions. At high concentrations of fumed silica a gel state is found, which in the case of the surface modified silica is a very weak gel that can be rejuvenated by ultrasonic treatment. The key parameter controlling the aggregation in this system is hydrogen bonding and the surface modification results in a very low number of sites for hydrogen bonding. In addition there is a contribution from repulsive electrostatic interactions in the surface modified silica dispersions due to the highly charged surfaces of these particles. Furthermore, the Li+-ion diffusion, at low silica concentration, is three orders of magnitude faster than that of the silica particles and in the gel state the silica particles are immobile. We also find that the Li+-ion diffusion is virtually independent of the silica concentration in the dispersions.

A locality aware cache diffusion system

Web caching is a widely deployed technique to reduce the load to web servers and to reduce the latency for web browsers. Peer-to-Peer (P2P) web caching has been a hot research topic in recent years as it can create scalable and robust designs for decentralized internet-scale applications. However, many P2P web caching systems suffer expensive overheads such as lookup and publish messages, and lack locality awareness. In this paper, we present the development of a locality aware cache diffusion system that makes use of routing table locality, aggregation, and soft state to overcome these limitations. The analysis and experiments show that our cache diffusion system reduces the amount of information processed by nodes, reduces the number of index messages sent by nodes, and improves the locality of cache pointers.

A multiple case history and systematic review of adoption, diffusion, implementation and impact of provincial daily physical activity policies in Canadian schools

BACKGROUND : Few children meet physical activity (PA) recommendations, and are therefore at increased risk for overweight/obesity and adverse health outcomes. To increase children's opportunities for PA, several Canadian provinces have adopted school-based daily PA (DPA) policies. It is not clear why some jurisdictions have adopted DPA policies, and others have not, nor whether these policies have been implemented and have achieved their intended outcomes. The purpose of this study was to understand the processes underlying adoption and diffusion of Canadian DPA policies, and to review evidence regarding their implementation and impact.

METHODS: We adopted a multiple case history methodology in which we traced the chronological trajectory of DPA policies among Canadian provinces by compiling timelines detailing key historical events that preceded policy adoption. Publicly available documents posted on the internet were reviewed to characterize adopter innovativeness, describe the content of their DPA policies, and explore the context surrounding policy adoption. Diffusion of Innovations theory provided a conceptual framework for the analyses. A systematic literature search identified studies that had investigated adoption, diffusion, implementation or impact of Canadian DPA policies.

RESULTS: Five of Canada's 13 provinces and territories (38.5%) have DPA policies. Although the underlying objectives of the policies are similar, there are clear differences among them and in their various policy trajectories. Adoption and diffusion of DPA policies were structured by the characteristics and capacities of adopters, the nature of their policies, and contextual factors. Limited data suggests implementation of DPA policies was moderate but inconsistent and that Canadian DPA policies have had little to no impact on school-aged children's PA levels or BMI.

CONCLUSIONS: This study detailed the history and current status of Canadian DPA policies, highlighting the conditional nature of policy adoption and diffusion, and describing policy and adopter characteristics and political contexts that shaped policy trajectories. An understanding of the conditions associated with successful policy adoption and diffusion can help identify receptive contexts in which to pioneer novel legislative initiatives to increase PA among children. By reviewing evidence regarding policy implementation and impact, this study can also inform amendments to existing, and development of future PA policies.

Machine-to-machine communications with in-network data aggregation, processing, and actuation for large-scale cyber-physical systems

Machine-to-Machine (M2M) paradigm enables machines (sensors, actuators, robots, and smart meter readers) to communicate with each other with little or no human intervention. M2M is a key enabling technology for the cyber-physical systems (CPSs). This paper explores CPS beyond M2M concept and looks at futuristic applications. Our vision is CPS with distributed actuation and in-network processing. We describe few particular use cases that motivate the development of the M2M communication primitives tailored to large-scale CPS. M2M communications in literature were considered in limited extent so far. The existing work is based on small-scale M2M models and centralized solutions. Different sources discuss different primitives. Few existing decentralized solutions do not scale well. There is a need to design M2M communication primitives that will scale to thousands and trillions of M2M devices, without sacrificing solution quality. The main paradigm shift is to design localized algorithms, where CPS nodes make decisions based on local knowledge. Localized coordination and communication in networked robotics, for matching events and robots, were studied to illustrate new directions.

The threat of autocracy diffusion in consolidated democracies? The case of China, Singapore and Australia

The majority of today’s authoritarian regimes have little hope of promoting autocracy beyond their own borders, let alone to consolidated democratic countries. However, China and Singapore are two prominent examples of non-democratic countries whose soft power arsenals have given them some global appeal beyond that enjoyed by most authoritarian regimes. But to what extent has China’s and Singapore’s power of example influenced consolidated democracies in terms that the latter wanting to replicate some political practices or even norms in these non-democratic regimes? In this article, we engage recent works to examine this question in relation to how Australians perceive the political example offered by China and Singapore. Focusing our analysis on several prominent polls conducted recently by the Lowy Institute for International Policy, we suggest that at present there is little evidence of a causal impact of the rise of authoritarian powerhouses such as China and Singapore on how Australians view democracy at home. Through these case studies, this article sheds some light on the theoretical as well as practical questions about the inherent impediments of authoritarian diffusion in consolidated democracies.