2,060 research outputs found

    On the Thermodynamics and Experimental Control of Twinning in Metal Nanocrystals

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    International audienceThis work demonstrates a new strategy for controlling the evolution of twin defects in metal nanocrystals by simply following thermodynamic principles. With Ag nanocrystals supported on amorphous SiO2 as a typical example, we establish that twin defects can be rationally generated by equilibrating nanoparticles of different sizes through heating and then cooling. We validate that Ag nanocrystals with icosahedral, decahedral, and single‐crystal structures are favored at sizes below 7 nm, between 7 and 11 nm, and greater than 11 nm, respectively. This trend is then rationalized by computational studies based on density functional theory and molecular dynamics, which show that the excess free energy for the three equilibrium structures correlate strongly with particle size. This work not only highlights the importance of thermodynamic control but also adds another synthetic method to the ever‐expanding toolbox used for generating metal nanocrystals with desired properties.

    Implementation of a herd management system with wireless sensor networks

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    This paper investigates an adaptation of Wireless Sensor Networks (WSNs) to cattle monitoring applications. The proposed solution facilitates the requirement for continuously assessing the condition of individual animals, aggregating and reporting this data to the farm manager. There are several existing approaches to achieving animal monitoring, ranging from using a store and forward mechanism to employing GSM-based techniques; these approaches only provide sporadic information and introduce a considerable cost in staffing and physical hardware. The core of this study is to overcome the aforementioned drawbacks by using alternative cheap, low power consumption sensor nodes capable of providing real-time communication at a reasonable hardware cost. In this paper, both the hardware and software has been designed to provide a solution which can obtain real-time data from dairy cattle whilst conforming to the limitations associated with WSNs implementations

    Formazanate Complexes of Hypervalent Group‐14 Elements as Precursors to Electronically Stabilized Radicals

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    The stability of molecular radicals containing main‐group elements usually hinges on the presence of bulky substituents that shield the reactive radical center. We describe a family of group‐14 formazanate complexes whose chemical reduction allows access to radicals that are stabilized instead by geometric and electron‐delocalization effects, specifically by the square‐pyramidal geometry adopted by the group‐14 atom (Si, Ge, Sn) within the framework of the heteroatom‐rich formazanate ligands. The reduction potentials of the Si, Ge, and Sn complexes as determined by cyclic voltammetry become more negative in that order. Examination of the solid‐state structures of these complexes suggested that their electron‐accepting ability decreases with increasing group‐14 atom size because a larger central atom increases the nonplanarity of the ligand‐based conjugated π‐electron system of the complex. The experimental findings were supported by density‐functional calculations on the parent complexes and the corresponding radicals

    How a turn to critical race theory can contribute to our understanding of 'race', racism and anti-racism in sport

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    As long as racism has been associated with sport there have been consistent, if not coordinated or coherent, struggles to confront its various forms. Critical race theory (CRT) is a framework established to challenge these racialized inequalities and racism in society and has some utility for anti-racism in sport. CRT's focus on social justice and transformation are two areas of convergence between critical race theorists and anti-racists. Of the many nuanced and pernicious forms of racism, one of the most obvious and commonly reported forms of racism in sport, racial abuse, has been described as a kind of dehumanizing process by Gardiner (2003), as those who are its target are simultaneously (re)constructed and objectified according to everyday myth and fantasy. However, this is one of the many forms of everyday racist experiences. Various forms of racism can be experienced in boardrooms, on television, in print, in the stands, on the sidelines and on the pitch. Many times racism is trivialized and put down as part of the game (Long et al., 2000), yet its impact is rarely the source of further exploration. This article will explore the conceptualization of 'race' and racism for a more effective anti-racism. Critical race theory will also be used to explore the ideas that underpin considerations of the severity of racist behaviour and the implications for anti-racism. © The Author(s) 2010
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