Shape evolution of silver nanoplates through heating and photoinduction

Shape conversions of silver nanoplates were realized by heating and subsequent light irradiation. The initial silver nanoprisms were transformed into silver nanodisks gradually in the process of heating, which was possibly achieved through dissolving and readsorption of silver atoms on the surface of silver nanoplates. Subsequently, under light irradiation, the heating induced silver nanodisks were reversed to silver nanoprisms in the same solution. The dissolved oxygen was found to play a pivotal role in the shape conversion from nanoprism to nanodisk. In addition to heating, deionized water could induce the shape conversion of silver nanoplates when it was added to precipitate of the initial silver nanoprisms after centrifugation. Citrate in solution is essential to the photoinduced shape conversion process. Transmission electron microscopy (TEM) and extinction spectroscopy results demonstrated that localized surface plasmon resonance (LSPR) properties of silver nanoplates were effectively tuned through shape conversion.

Tri-component bio-composite materials prepared using an eco-friendly processing route

We report on the blending of three natural polymers, raw cotton, silk and wool, using ionic liquids as the dissolving media. We find that with increased content of wool and silk the thermal degradation temperature of the new bio films increases. This is due to an increase in the hydrogen bond network between the blended polymers. We also investigated the role of the coagulating solvent by coagulating the bio films using water, methanol or isopropanol. Again, we find the coagulating solvent impacts the final properties of the bio films with water shown to coagulated films with the best material properties.

Composite yarns fabricated from continuous needleless electrospun nanofibers

In this work, a spinning metal wire collector was employed to continuously collect polyacrylonitrile (PAN) nanofibers produced by a disc fiber generator and coil them around a polyethylene terephthalate (PET) yarn. The obtained composite yarns exhibited a core/shell structure (PET yarn/PAN nanofibers) with nanofibers orderly arranged on the surface of the PET yarn. The electric field analysis showed that the position of metal wire had insignificant effect on the formed electric field and high intensity electric field was formed at the disc circumferential area, which provided a constant electric field for the production of uniform nanofibers. The spinning solution, spinning speed of metal wire, and winding speed were found to play an important role in producing good quality nanofiber yarns, in terms of morphology, strength, and productivity. Pure nanofiber yarns were obtained after dissolving the core yarns in a proper solvent. This method has shown potential for the mass production of nanofiber yarns for industrial applications.

Preparation of polyacrylonitrile–natural polymer composite precursors for carbon fiber using ionic liquid co solvent solutions

We report on the use of ionic liquid co-solvents in the preparation of polyacrylonitrile–natural polymer carbon fibers as low cost environmentally friendly alternatives to conventional carbon fibers precursors and processing solvents. We have characterized the structure properties of the new composites as a function of dissolving solvent using solid state NMR, DSC, FTIR and TGA. We show that the dissolving solvent plays a significant role in the properties of the new composites, we also find that the incorporation of the natural polymer additive impacts the thermal transition temperatures for the PAN

Evaluating the corrosion behaviour of magnesium alloy in simulated biological fluid by using SECM to detect hydrogen evolution

Scanning electrochemical microscopy (SECM) in surface generation/tip collection mode is investigated as an assessment tool for studying the corrosion behaviour of magnesium in simulated biological fluid. The technique provides a local map of hydrogen (H2) evolution which alone can be used as a direct measure of corrosion. The H2 generated during corrosion of magnesium is oxidized at the probe(i.e. a Pt ultra micro-electrode);with the magnitude of the current generated due to oxidation being indicative of the intensity of H2 evolution at a local scale on the magnesium surface. This method was calibrated using a cathodically polarized Pt disk to simulate H2 evolution in a controlled condition on a homogeneous surface. Potential interference from dissolving Mg or high local pH was also investigated. The technique was implemented for studying H2 evolution at the surface of AZ31 as a model Mg alloy.SECM results combined with SEM-EDX and profilometry data revealed that local domains of higher H2 evolution on the surface of AZ31 are in close proximityof the observed pitting sites.

Ultrafine PDMS fibers: Preparation from in situ curing-electrospinning and mechanical characterization

Polydimethylsiloxane (PDMS) fibers with unexpected elasticity were prepared by a modified core-shell electrospinning method using a commercially-available liquid PDMS precursor (Sylgard 184) and polyvinylpyrrolidone (PVP) as core and sheath materials, respectively. The liquid PDMS precursor was crosslinked in situ to form a solid core when the newly-electrospun core-sheath nanofibers were deposited onto a hot-plate electrode collector. After dissolving the PVP sheath layer off the fibers, net PDMS fibers showed larger average diameter than core-sheath fibers, with an average diameter around 1.35 μm. The tensile properties of both single fibers and fibrous mats were measured. Single PDMS fibers had a tensile strength and elongation at break of 6.0 MPa and 212%, respectively, which were higher than those of PDMS cast film (4.9 MPa, 93%). The PDMS fiber mat had larger elongation at break than the single PDMS fibers, which can be drawn up to 403% their original length. Cyclic loading tests indicated a Mullin effect on the PDMS fiber mats. Such a superior elastic feature was attributed to the PDMS molecular orientation within fibers and the randomly-orientated fibrous structure. Highly-elastic, ultrafine PDMS fibers may find applications in strain sensors, biomedical engineering, wound healing, filtration, catalysis, and functional textiles. © The Royal Society of Chemistry 2014.

Stillness and movement: a bodily approach to photography

My paper will address both Duration and temporality of the ‘still’ imageand Sensorial and bodily experience of photography through a discussion of a recent body of work ‘Fly Rhythm’, a series of photographs and video works exhibited in a gallery context.By acknowledging the inter-relationship between the body and the camera my project seeks to challenge a perceived separation between performance and photography. Fly Rhythm was conceived through a performative somatic process. Through using a custom made camera I was able to negotiate time and space to create a visual drawing of movement and stillness together in photography. The resultant images are discussed as a notation of body movement – a record of bodily history enabled through a self imposed discipline of learning to read light.I initially constructed a human size camera to understand how photography works. Spending time inside observing the way light moves and affects the formation of sight is also a way of embodying the act of photography. I responded by making a bespoke camera that enabled light to be captured during extended periods while moving. My project is dependent upon a self-imposed discipline of intuiting light’s strength and erratic changes, a skill developed by making analogue prints while inside a camera obscura. Once I had developed an ability to read light’s changes and gain an understanding of camera mechanics I made durational recordings moving through the landscape on Bruny Island Tasmania and industrial sites in Melbourne, photographs exhibited as part of Fly Rhythm. I will discuss these prints in context with the idea that light is a conduit through which past and present fuse together in a bodily act of photographing and processing images.I will explore durational aspects of photography by discussing light’s relative motion while taking photographs without using the viewfinder or composing images in the traditional way. Rather, the camera at the end of my arm is directed through how I read light therefore a choreography notated in the prints – a kind of body signatureMy practice enables a new the way of seeing, in a spontaneous hand held process creating a sense of embodiment. By analyzing process my paper will consider how the body together with analogue and 21st century digital technology coalesce cross-disciplinary practice combining visual art, performance and photographic disciplines.I also explored limitations of digital light in contrast with ‘natural’ light by a making a gamut of dissolving colour determined by the software based on two pixels. Projected into the ambient light ‘Glide’ is an 11minute durational work installed at the Substation Contemporary Art Space in Melbourne Australia.

Cyborg presence in narrative theatre

New technologies are transforming the shape and function of contemporary performance practice. Dance in particular has been at the forefront of dissolving the boundaries between humans and technology. In Australia alone, works such as Gideon Obarzanek's GLOW (Chunky Move) and Garry Stewart's Proximity (Australian Dance Theatre) have offered technology a role traditionally preserved only for the live human performer. As these technologies infiltrate theatre practice and their capacity to be co-actors with humans on stage increases, we need to carefully interrogate the notion of the actor's presence. For an overwhelming number of scholars and critics, presence is the defining quality of theatrical performance. Theatre has been privileged as the site where people witness other people together in the same physical space. Digital technologies can be seen as a threat to this and to the actor's presence. Cormac Power's Presence in Play provides a comprehensive analysis of theatrical presence that encapsulates a poststructuralist critique of presence while maintaining the notion of 'presence' as a key aspect of theatre. In this article, I take up Power's category of the literal mode of presence and examine three case studies that use digital technology in ways that disturb traditional conceptions of presence. I investigate the impact that digital technologies in live performance have on theatre's claims to literal presence. I also investigate the indirect impact that these technologies have on forms of fictional and auratic presence (these are Power's terms, which I will define shortly). First, I will establish the centrality of presence to the vast body of commentary on theatre; then, I will draw on Derrida's analysis of the metaphysics of presence to unsettle dominant assumptions about the function of presence in theatre, arguing that such a privileging of presence demonises projected media as a form of contamination that impedes theatre's ability to represent 'truth'. I use Jennifer Parker-Starbuck's term 'Cyborg Theatre' to discuss three examples of digital performance that have used technology to question and challenge our relationship to technology in everyday life. These works challenge traditional notions of selfhood and force us to interrogate the borders between the live and the mediated.

Síntese de pigmentos cerâmicos inorgânicos nanométricos e encapsulados com estrutura core-shell pela rota dos precursores poliméricos

The present work has as objective the development of ceramic pigments based in iron oxides and cobalt through the polymeric precursor method, as well as study their characteristics and properties using methods of physical, chemical, morphological and optical characterizations.In this work was used iron nitrate, and cobalt citrate as precursor and nanometer silica as a matrix. The synthesis was based on dissolving the citric acid as complexing agent, addition of metal oxides, such as chromophores ions and polymerization with ethylene glycol. The powder obtained has undergone pre-ignition, breakdown and thermal treatments at different calcination temperatures (700 °C, 800 °C, 900 °C, 1000 °C and 1100 °C). Thermogravimetric analyzes were performed (BT) and Differential Thermal Analysis (DTA), in order to evaluate the term decomposition of samples, beyond characterization by techniques such as BET, which classified as microporous materials samples calcined at 700 ° C, 800 º C and 900 º C and non-porous when annealed at 1000 ° C and 1100 º C, X-ray diffraction (XRD), which identified the formation of two crystalline phases, the Cobalt Ferrite (CoFe2O4) and Cristobalite (SiO2), Scanning Electron Microscopy (SEM) revealed the formation of agglomerates of particles slightly rounded;and Analysis of Colorimetry, temperature of 700 °C, 800 °C and 900 °C showed a brown color and 1000 °C and 1100 °C violet

ACUTE TOXICITY of SODIUM SELENITE and SODIUM SELENATE TO TILAPIA, Oreochromis niloticus, FINGERLINGS

Selenium is an essential nutrient for many organisms, including fish. It can be released in the water by natural processes of dissolving rocks and minerals, and by the wastewater from industries and agricultural activities, which can increase its concentration in the environment, leading to toxic effects to the aquatic biota. Median Lethal Concentrations (LC(50-96h)) of two forms of selenium were estimated to fingerlings of Nile tilapia Oreochromis niloticus, focusing on estimating indicators for future environmental risk assessments in aquatic ecosystems contaminated with those elements, particularly for evaluate sources of water quality suitable for rearing tilapia. The results were: LC(50-96h) of sodium selenite (Na(2)SeO(3)) = 4.42 mg Se(4+) L(-1), and LC(50-96h) of sodium selenate (Na(2)SeO(4)) = 14,67 mg Se(6+) L(-1). According to those data, it was possible to classify sodium selenite as highly toxic and sodium selenate as moderately toxic to fingerlings of tilapia.

Thermal characterization of solid lipid nanoparticles containing praziquantel

Solid lipid nanoparticles (SLNs), loaded and unloaded with praziquantel (PRZ-load SLN and PRZ-unload SLN) were prepared by two different procedures: (a) oil-in-water hot microemulsion method, obtaining at 70 degrees C an optically transparent blend composed of surfactant, co-surfactant, and water; and (b) oil-in-water microemulsion method, dissolving the lipid in an immiscible organic solvent, emulsified in water containing surfactants and co-surfactant, and then evaporated under reduced pressure at 50 degrees C. The mean diameter, polydispersity index (PdI), and zeta potential were 187 to 665 nm, 0.300 to 0.655, and -25 to -28 mV respectively, depending on the preparation method. The components, binary mixture, SLNs loaded and unloaded with PRZ, and physical mixture were evaluated by differential scanning calorimetry (DSC) and thermogravimetry (TG). The non-isothermal isoconversional Flynn-Wall-Ozawa method was used to determine the kinetic parameters associated with the thermal decomposition of the samples. The experimental data indicated a linear relationship between the apparent activation energy E and the pre-exponential factor A, also called the kinetic compensation effect (KCE), allowing us to determine the stability with respect to the preparation method. Loading with PRZ increased the thermal stability of the SLNs.

Comércio internacional e meio ambiente: estímulo à produção sustentável ou mero protecionismo comercial a posição do Brasil em dois casos de litígio

The World Trade Organization (WTO) was established in 1994 as a result of the Uruguay Round, and has as its principal aim advocate for the maintenance of free trade between nations. The preamble of its Constitutive Agreement specifically cites as an institution the goal of achieving sustainable development and the pursuit of protecting and preserving the environment, bringing into the sphere of world trade the idea that concern for the environmental cause is not restricted only the group of environmentalists, but rather has entered the economic landscape in a way not only ideological, but also pragmatic. The General Agreement on Tariffs and Trade (GATT) 1947, part of the GATT 1994, contains a device that allows the adoption of trade restrictive measures, provided that such measures aimed at protecting the environment - Article XX. The Settlement Body (DSB) is part of the WTO and acts in dissolving disputes between the countries motivated by trade. It examines two cases where countries have imposed restrictive trade measures with environmental justification. The first case was closed in 1996, with award of damages given to Brazil, on the breakdown of U.S. environmental legislation imposed on imported gasoline from Brazil - and the second, begun in 2005 and closed in 2007, coming out victorious again Brazil is on the import ban on retreaded tires to Brazil. The objective is to answer the question: how the environment is treated in the midst of trade discussions - which is aimed at its protection or its use with economic objectives in disguise? For the preparation of this work, extensive documentary research was undertaken with the virtual site of the WTO to review the entire production of legal cases and subsequent analysis of the key issue for the work, and literature of authors who have studied the tense relationship between trade international environment. The first case, it could be seen that the political movement performed by the U.S. with the aim of achieving acceptable standards of air quality was an institutional effort to ensure the quality of air, and thus would be inappropriate to say that the regulation of gasoline was merely a disguised trade barrier.However, a careful analysis of the implementation and operation of gasoline regulation may reveal intentions disguised trade and U.S. environmental argument did not hold. The weight of this environment was relegated, since there were clearly outside interests to the environmental cause. The second case, it was realized that, despite clear attempts by the EC to promote ecological dumping, send when brought to Brazil, supposedly a country with weaker environmental structure on surveillance, a residue that, pursuant to internal policies, as could not be sent to their own landfills, the Brazilian discourse remained focused on the environmental cause, and this sort there was the existence of disguised trade barriers, but of importance, at least a priori, the discussion of foreign forces on the environment environment because there is no way to legally justify the reversal of the total understanding of the first judging body, the sight of all the arguments presented by Brazil and the nonsubmission of new facts upon appeal. Still, quite heartening to reflect on the role of trade liberalization on the environment in general, because, while they do not reach a definitive conclusion will reveal positions in both directions, both for and against, the that only adds to the discussions and makes this a very fertile topic for future research

Hydro(radio)chemical relationships in the giant Guarani aquifer, Brazil

This investigation was carried out within the Parana sedimentary basin and involved the sampling of 78 pumped tubular wells for evaluating the hydrochemistry and radioactivity due to the nuclides (238)U, (234)U, (222)Ra, (226)Ra, and (228)Ra in the Brazilian part of Guarani aquifer. Several significant correlations were found involving the geostatic pressure, for instance, specific flow rate, CO(3)(2-), SO(4)(2-) temperature, dissolved O(2), free CO(2), pH, redox potential Eh, conductivity, Na, HCO(3)-, CO(3)(2-) , SI(calcite), Cl(-), F(-), SO(4)(2-), and B. Carbonates precipitation was evidenced by inverse correlation between CO(3)(2-) and Ca, Mg, Sr, and Ba, whereas Na exhibited an opposite trend, dissolving rather than precipitating with increasing CO(3)(2-) concentration. An inverse correlation between 3 and K was found, possibly related to the increasing tendency of K to recombine with the thickness of the clayey layers. HCO(3)-played an important role on Na, Ca, Mg, and Sr dissolution. The dissolved U content and (234)U/(238)U activity ratio data were plotted on a two-dimensional diagram that was successfully utilized on identifying an unreported zone of U accumulation, though not necessarily of economic size and grade. The variability in chemical and radionuclides data indicated an important influence of the underlying Paleozoic sediments in the composition of waters from Guarani aquifer. The available data allowed estimate the groundwater residence time by two U-isotopes disequilibrium methods. Values of 45-61 ka were initially calculated, depending on the adopted porosity (15-20%), but a longer residence time (- 640 ka) was also estimated, which is more compatible with the hydraulic conductivity data in Guarani aquifer and groundwater flow velocity occurring at Milk River aquifer, Alberta, Canada. Such time range agrees with previously reported (14)C ages exceeding 30 ka BP at the more central parts of the Parana sedimentary basin. (c) 2005 Elsevier B.V. All rights reserved.

Correlation of reactivity with structural factors in a series of Fe(II) substituted cobalt ferrites

A series of powdered cobalt ferrites, CoxFe3-xO4 with 0.66 <= x< 1.00 containing different amounts of Fe-II, were synthesized by a mild procedure, and their Fe and Co site occupancies and structural characteristics were explored using X-ray anomalous scattering and the Rietveld refinement method. The dissolution kinetics, measured in 0.1 M oxalic acid aqueous solution at 70 degrees C, indicate in all cases the operation of a contracting volume rate law. The specific rates increased with the Fell content following approximately a second-order polynomial expression. This result suggests that the transfer of Fe-III controls the dissolution rate, and that the leaching of a first layer of ions Co-II and Fe-II leaves exposed a surface enriched in slower dissolving octahedral Fe-III ions. Within this model, inner vicinal lattice Fe-II accelerates the rate of Fe-III transfer via internal electron hopping. A chain mechanism, involving successive electron transfers, fits the data very well. (C) 2006 Elsevier B.V. All rights reserved.

Persuasão antes que convencimento: apontamentos sobre Wittgenstein e a psicanálise

As relações que Wittgenstein mantém com o pensamento de Freud, como atestaram vários estudiosos, são marcadamente ambíguas: existe, por um lado, uma crítica acerba do caráter pseudocientífico com que a psicanálise apresenta supostas “descobertas empíricas”, e do fascínio exercido por este modo de proceder; mas há, por outro lado, evidências da sua admiração pelo efeito dissolvente do uso de metáforas e interpretações, chegando mesmo Wittgenstein a incorporar essa estratégia ao seu próprio método de investigação lógica dos conceitos filosóficos. Neste trabalho pretendo retirar de uma reflexão acerca do método incorporado às Investigações Filosóficas, comparável em muitos aspectos à clínica de uma psicanálise lingüística dessubstancializada, alguns pontos positivos que se poderiam acrescentar à crítica da concepção de linguagem de Lacan.