157 research outputs found

    On the role of 4-methoxypyridine in the electrochemical formation of plasmonic gold nanoparticles

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    This thesis details an electrochemical approach to generate homogenous and densely populated films of anisotropic gold nanoparticles. The electrochemistry of coinage metals in the presence of the ligand 4-methoxypyridine (MOP) is described in detail and the role of the ligand in the formation of nanoparticle films on conductive substrates is discussed. The thesis demonstrates application of Stopped-flow UV-Vis spectroscopy to evaluate and study the kinetics of the homogenous chemistry of MOP with the gold salt precursor. It discusses the role of Au(I) ions, and the different species involved in the complex Au-MOP system by thermodynamic and kinetic analysis. The thesis illustrates the excellent suitability of these nanoparticle films for surface-enhanced Raman scattering (SERS) applications utilizing near-IR excitation sources. The chronoamperometric study described in the thesis demonstrates the nucleation and growth mechanism of the electrodeposited gold nanostructures. Overall, the work described in this thesis outlines the advancement of electrochemical platforms that pertains to the potential applications of anisotropic gold nanostructures by tuning the shapes and size of the nanostructures

    DNA Block Copolymers - synthesis, morphologies and applications

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    Graphics Technology in Space Applications (GTSA 1989)

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    This document represents the proceedings of the Graphics Technology in Space Applications, which was held at NASA Lyndon B. Johnson Space Center on April 12 to 14, 1989 in Houston, Texas. The papers included in these proceedings were published in general as received from the authors with minimum modifications and editing. Information contained in the individual papers is not to be construed as being officially endorsed by NASA

    The 1994 Silver Anniversary of APOLLO 11: From the Moon to the Stars

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    This report summarizes the technology transfer, advanced studies, and research and technology efforts in progress at Marshall Space Flight Center (MSFC) in 1994

    COBE's search for structure in the Big Bang

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    The launch of Cosmic Background Explorer (COBE) and the definition of Earth Observing System (EOS) are two of the major events at NASA-Goddard. The three experiments contained in COBE (Differential Microwave Radiometer (DMR), Far Infrared Absolute Spectrophotometer (FIRAS), and Diffuse Infrared Background Experiment (DIRBE)) are very important in measuring the big bang. DMR measures the isotropy of the cosmic background (direction of the radiation). FIRAS looks at the spectrum over the whole sky, searching for deviations, and DIRBE operates in the infrared part of the spectrum gathering evidence of the earliest galaxy formation. By special techniques, the radiation coming from the solar system will be distinguished from that of extragalactic origin. Unique graphics will be used to represent the temperature of the emitting material. A cosmic event will be modeled of such importance that it will affect cosmological theory for generations to come. EOS will monitor changes in the Earth's geophysics during a whole solar color cycle

    European Union Timber Regulation Impact on International Timber Markets

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    The trade of illegal timber, often from illegal logging, has severe environmental, social and economic consequences. The EU’s response to this problem came with the Forest Law Enforcement, Governance and Trade (FLEGT) Action Plan, with its specific goal to end illegal logging, thereby improving sustainability of forest resources. In March 2013, an additional step was taken by implementing the EU Timber Regulation (EUTR). The EUTR requires proof of timber’s origin and legality to ensure that no illegal timber is imported into the EU. To this end the EU intends to block imports of any wood or wood product which comes from unknown sources. Certification of sustainable forest management will help EU importers minimize risk, which is an essential part of their required due diligence system. Monitoring organizations are established to assist trade associations and businesses to construct comprehensive due diligence systems. National competent authorities are designated to follow the trade of the new FLEGT-licensed timber and timber products. In the first year of the EUTR there are positive impacts, of which the most important is awareness of the disastrous situation with illegal logging, driven by exports of illegal timber. Another positive development is tropical timber exporters documenting the legality of their wood exports. Yet another positive feature is establishment of due diligence systems by EU importers. However, there are considerable problems for ensuring legal trade; for example the lack of comprehensive documentation of origin and legality. Analysis of recent trends establishes changes in the European timber trade in terms of sourcing, substitution, diversion to less-demanding countries. Short-term forecasts of market trends and changes will enable further policy assessment to achieve the objectives of improved legality in international timber markets.JRC.H.3-Forest Resources and Climat

    Handbook of Mathematical Geosciences

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    This Open Access handbook published at the IAMG's 50th anniversary, presents a compilation of invited path-breaking research contributions by award-winning geoscientists who have been instrumental in shaping the IAMG. It contains 45 chapters that are categorized broadly into five parts (i) theory, (ii) general applications, (iii) exploration and resource estimation, (iv) reviews, and (v) reminiscences covering related topics like mathematical geosciences, mathematical morphology, geostatistics, fractals and multifractals, spatial statistics, multipoint geostatistics, compositional data analysis, informatics, geocomputation, numerical methods, and chaos theory in the geosciences

    Self-assembly of rod-like colloids at the air-water interface

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    Two-dimensional (2D) colloidal materials and their assembly are of scientific significance and industrial importance. The development of 2D colloidal structures is a key stepping stone towards three-dimensional (3D) structures in relation to controlled chemical composition, morphology, assembly and so on. Nowadays, uniform colloidal structures with complexity in both shape and interactions have become a popular topic in fundamental colloid science and applications. Being motivated by this, in this thesis, micro-scale colloidal rods and self-assembled dipeptides have been studied experimentally at the air-water interface. Monolayers containing these colloidal materials were created in a Langmuir trough. Surface pressure measurements, microscopic observations and many other techniques were combined for the investigation. The aim of this work is to understand the phase behaviours in complex monolayers, including the phase transitions during compression, the flipping dynamics of micro-rods, the contribution of dipole-dipole interactions between magnetic rods, and the interfacial self-assembly process of dipeptide molecules. Iron oxide micro-rods (β-FeOOH @silica) with different aspect ratios have been synthesized to create the monolayers at an air-water interface. Microscopic observations reveal a sequence of phase transitions by compressing the monolayers. It has been proved that the aspect ratio of the rods plays an important role in the phase transitions, —short rods flip into a perpendicular position relative to the interface to relieve the compressional stress, while longer rods form multilayers under compression. Magnetic rods (Fe3O4) were converted from the synthesized FeOOH rods. They can be aligned in an external field, which further induces the reorganization at the interface. To study these magnetic rods, differential dynamic microscopy (DDM) was carried out to measure the magnetic moment. Their interfacial properties were investigated in an external field applied perpendicular and parallel to the interface, respectively. A magnetic field-induced flipping process has been observed, which proves the theoretical prediction. Besides rod-like particles, naphthalene dipeptides have been successfully trapped at the interface of a low pH subphase, self-assembling into a hydrogel film. The mechanism of interfacial self-assembly has been studied. Both FTIR spectra and AFM images are used to investigate the fibrous structures of the film. The film has elastic properties and buckles under compression. Moreover, dipeptide hydrogel induced by metal ions has been used to create a wet foam system, which owns the advantages of long-term stability (more than two weeks), low cost, and easy preparation
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