Micro–Raman Spectroscopy of Diamonds from JaH 054 and Sahara 98505 Ureilites, Statistic Research

In this paper Raman spectra of diamonds from two different ureilites, JaH 054 and Sahara 98505, were measured. Obtained results for both ureilites showed the Raman shift ranged between 1321 cm -1 and 1336 cm -1 for JaH 054 and between 1329 cm -1 and 1336 cm -1 for Sahara 98505. FWHM parameter (full width at half maximum) varied also in wide range especially for Sahara 98505. Raman imaging was done for JaH 054 sample and diamonds of different Raman shifts (1321 cm-1, 1328 cm-1, 1330 cm-1) were found in few tens (im sized area of carbon vein. Raman peaks of ureilitic diamonds were compared with literature data of laboratory diamonds produced under high pressure, under low pressure with MW PACVD method and with other ureilites. Presented research showed that even in highly shocked ureilites Raman shift versus FWHM parameter plots are similar with CVD diamonds for ureilites. However, the origin of diamonds in ureilites is not explained based on the obtained results, close coexistence of different diamonds in investigated ureilites suggests that the mechanism of diamond creation in meteorites was very complex and could be multi-step process

High-resolution Raman microscopy of curled carbon nanotubes

The use of confocal Raman imaging spectroscopy and atomic force microscopy for identifying conditions of carbon nanotubes with bent nanotube bundles in the bent state was described. It was found that the tangential G mode on Raman spectra systemically shifts downward upon nanotube bending. The frequency shifts observed in the nanotubes were due to tensile strain of the bending nanotube arrays, which resulted in the loosening of C-C bonds in the outer walls. It was speculated that the frequency shift in Raman spectra was used for fast monitoring of the bending state of the standing carbon nanotube in gas and fluid flow nanosensors.open282

Behavior of Particle Depots in Molten Silicon During Float-Zone Growth in Strong Static Magnetic Fields

In the photovoltaics industry, the largest market share is represented by solar cells made from multicrystalline silicon, which is grown by directional solidification. During the growth process, the silicon melt is in contact with the silicon nitride coated crucible walls and the furnace atmosphere which contains carbon monoxide. The dissolution of the crucible coating, the carbon bearing gas, and the carbon already present in the feedstock, lead to the precipitation of silicon carbide, and silicon nitride, at later stages of the growth process. The precipitation of Si3N4 and SiC particles of up to several hundred micrometers in diameter leads to severe problems during the wire sawing process for wafering the ingots. Furthermore the growth of the silicon grains can be negatively influenced by the presence of particles, which act as nucleation sources and lead to a grit structure of small grains and are sources for dislocations. If doped with Nitrogen from the dissolved crucible coating, SiC is a semi conductive material, and can act as a shunt, short circuiting parts of the solar cell. For these reasons, the incorporation of such particles needs to be avoided. In this contribution we performed model experiments in which the transport of intentionally added SiC particles and their interaction with the solid-liquid interface during float zone growth of silicon in strong steady magnetic fields was investigated. SiC particles of 7m and 60m size are placed in single crystal silicon [100] and [111] rods of 8mm diameter. This is achieved by drilling a hole of 2mm diameter, filling in the particles and closing the hole by melting the surface of the rod until a film of silicon covers the hole. The samples are processed under a vacuum of 1x10(exp -5) mbar or better, to prevent gas inclusions. An oxide layer to suppress Marangoni convection is applied by wet oxidation. Experiments without and with static magnetic field are carried out to investigate the influence of melt convection on the distribution of particles and their incorporation into the crystal. The field strengths applied by a superconducting magnet are 1T, 3T, 4.5T, and 5T. The increase in field strength dampens the melt flow, and so this study provides comparative data to the crystal growth experiment to be carried out onboard the sounding rocket mission TEXUS 51, where purely diffusive growth condition will be achieved under microgravity conditions

Behavior of Particle Depots in Molten Silicon During Float-Zone Growth in Strong Magnetic Fields

Solar cells made from directionally solidified silicon cover 57% of the photovoltaic industry's market [1]. One major issue during directional solidification of silicon is the precipitation of foreign phase particles. These particles, mainly SiC and Si3N4, are precipitated from the dissolved crucible coating, which is made of silicon nitride, and the dissolution of carbon monoxide from the furnace atmosphere. Due to their hardness and size of several hundred micrometers, those particles can lead to severe problems during the wire sawing process for wafering the ingots. Additionally, SiC particles can act as a shunt, short circuiting the solar cell. Even if the particles are too small to disturb the wafering process, they can lead to a grit structure of silicon micro grains and serve as sources for dislocations. All of this lowers the yield of solar cells and reduces the performance of cells and modules. We studied the behaviour of SiC particle depots during float-zone growth under an oxide skin, and strong static magnetic fields. For high field strengths of 3T and above and an oxide layer on the sample surface, convection is sufficiently suppressed to create a diffusive like regime, with strongly dampened convection [2, 3]. To investigate the difference between atomically rough phase boundaries and facetted growth, samples with [100] and [111] orientation were processed

Time invaders:conceptualizing performative game time

This chapter characterizes framing devices and other game elements as unstable signifiers, evaluating performances according to how they generate diachronic or synchronic effects by acting on those signifiers. Videogames make use of computers’ capabilities to present a very large set of these signifiers and thus generate highly complex forms of temporal experience. Because neither diachrony (exemplified by player performance) nor synchrony (computer-coded rule structures) can complete their respective operations and always leave a differential margin, videogames can be understood as diachrono-synchronic systems.Performative multiplicities of various sizes can be analyzed in terms of how they draw together or separate performances, creating a comparative methodology for describing temporal experience in videogames. One of the key synchronic effects is the Game Over, which has a high-level effect on all performances of a game. Considered as a synchronic horizon of experience, the Game Over provides a concept capable of addressing the heterogeneous and composite set of videogame elements in terms of how players interpret unstable signifiers. This includes narrative, which can be rigorously defined in terms of its synchronizing effect on a game’s performative multiplicity

Play and the exhibition:the problematic fun of showcasing of videogames in informal and formal contexts

Video games are inherently problematic as cultural artefacts, presenting issues of stability, currency, interaction and participation (to name but a few) in their curation. These issues are not necessarily unique to video games in an exhibition context, but their combination with the on-going debate about the status of video games as an art form inspire discussion and debate. Despite the issues presented by video games, there have been countless video game exhibitions in formal and informal contexts, typically focussing upon the historical narrative around games or their position as artefacts with cultural value. It is only in the last few years that artistic and academic study of this problematic field has developed traction, through both an emerging body of literature looking to formalise video games exhibitions practices and practitioner debate. 2019 sees the inaugural Game Arts International Assembly “a think tank for the international games arts ecosystem” bringing together leading curators and makers working at the forefront of public display of interactive arts and playful media.This paper contributes to the developing body of knowledge which analyses video games exhibition methods by formalising and evaluating the methods utilised within informal and formal contexts of video games exhibition from the perspective of reception theory. The study of both large scale exhibition such as those orchestrated by the Victoria and Albert museum and the Smithsonian American Art Museum alongside the one night indie game night or play party is a unique contribution to the field, with studies typically focussing on approaches within one given context. Reception theory provides a lens through which the active participative role of the attendee or visitor in meaning making can be evaluated and allows consideration of the connection between selected methods of exhibition and the resulting meaning making opportunities possible for a range of potential audiences

Towards an ethical ecology of international service learning

International Service-Learning (ISL) is a pedagogical activity that seeks to blend student learning with community engagement overseas and the development of a more just society. ISL programmes have grown as educational institutions and non-governmental organisations have sought to achieve the goal of developing ‘global citizens’. However, Service Learning (SL) in general and International Service-Learning (ISL) in particular remain deeply under theorised. These educational initiatives provide policy makers with a practical response to their quest for a ‘Big Society’and present alluring pedagogical approaches for Universities as they react to reforms in Higher Education and seek to enhance both the student learning experience and graduate employability. After outlining the development of ISL in policy and practice, this paper draws on the rich tradition of ISL at one British university to argue that ISL is a form of engagement that has the potential to be ethical in character although we identify a number of factors that militate against this. Our contention is that ISL which promotes rationaland instrumental learning represents a deficit model and we therefore conceptualise ISL here as a transformative learning experience that evinces distinctly aesthetic and even spiritual dimensions. Upon this theoretical groundwork we lay the foundations for conceptualizing ISL in ways that ensure its ethical integrity