Sampling and analytical methods of the National Status and Trends Program Mussel Watch Project: 1993-1996 Update

Polycyclic aromatic hydrocarbons, butyltins, polychlorinated biphenyls, DDT and metabolites, other chlorinated pesticides, trace and major elements, and a number of measures of contaminant effects are quantified in bivalves and sediments collected as part of the NOAA National Status and Trends (NS&T) Program. This document contains descriptions of some of the sampling and analytical protocols used by NS&T contract laboratories from 1993 through 1996. (PDF contains 257 pages

Plasma polymerisation: study and application

Molecular interactions are often studied using immobilised organic and biological entities at the surface of a substrate. Functionalisation of such surfaces can be achieved via different technologies such as Langmuir-Blodgett films, self-assembled monolayers and spin-coated layers. The main drawback of these methods is the dependence on the substrate, limiting the scope of possible applications. Conversely, plasma polymerisation entails the deposition of thin polymeric films at the surface of a wide variety of substrates. The development of pulsed plasma has opened new paths allowing the high controllability of the functionality and the thickness of the deposited layer. This thesis describes the functionalisation of a surface with pentafluorophenyl ester in a one-step process, reaching higher immobilization yield of bio-molecules than in a multi-step process. Also, the nature of pulsed-plasma polymers provides additional benefits such as irregular surfaces which make functionalities more accessible for subsequent reactions such as enzymatic modification as investigated in the fourth chapter. Finally, the last two chapters of this thesis deal with the occurrence of trapped free radicals within plasma polymers and their ability to induce graft-polymerisation of polymer brushes without prior attachment of initiators at the surface of a substrate. A comparison is drawn between a 'conventional' method using an initiator immobilised on the surface and trapped radicals to induce graft polymerisation. The influence of he nature of the monomer used during plasma polymerisation along with the conditions of deposition are studied with respect to the rate of subsequent graft polymerisation of styrene and the amount of trapped free radicals

A Comparative Study of Pt Depositing Methods (Chemical Reduction vs Photo-Assisted Deposition) onto TiO2 Nanoparticles for Hydrogen Photo-Production

In this paper, we report a comparative study on two methods (chemical reduction and photo-assisted deposition) of incorporating Pt onto TiO2 nanoparticles (TNP) for H2 generation. The phase structure of the photocatalysts was scrutinized utilizing TEM and XRD. The degree of dispersion of Pt on the TNP was calculated by a pulse chemisorption technique using TPDRO equipment. The results provided by TEM imagery, EDX spectra, elemental mapping, and AAS confirmed the successful deposition of Pt on TNP. XRD patterns confirmed an anatase and rutile crystallite structure, while UV-Vis spectra showed reduction of the bandgap from a typical value of 3.2 eV to ca. 2.9 eV. It was found that there is a correlation between the deposited Pt and dispersed Pt on the TNP with H2 generation. The chemical reduction method offered a higher degree of Pt deposition, resulting in a 2.75 times larger amount of deposited Pt compared to photodeposition. This feature is perceived to contribute a higher H2 yield (3,283 µmol) at 1 w% of Pt loading

A Comparative Study of Pt Depositing Methods (Chemical Reduction vs Photo-Assisted Deposition) onto TiO2 Nanoparticles for Hydrogen Photo-Production

In this paper, we report a comparative study on two methods (chemical reduction and photo-assisted deposition) of incorporating Pt onto TiO2 nanoparticles (TNP) for H2 generation. The phase structure of the photocatalysts was scrutinized utilizing TEM and XRD. The degree of dispersion of Pt on the TNP was calculated by a pulse chemisorption technique using TPDRO equipment. The results provided by TEM imagery, EDX spectra, elemental mapping, and AAS confirmed the successful deposition of Pt on TNP. XRD patterns confirmed an anatase and rutile crystallite structure, while UV-Vis spectra showed reduction of the bandgap from a typical value of 3.2 eV to ca. 2.9 eV. It was found that there is a correlation between the deposited Pt and dispersed Pt on the TNP with H2 generation. The chemical reduction method offered a higher degree of Pt deposition, resulting in a 2.75 times larger amount of deposited Pt compared to photodeposition. This feature is perceived to contribute a higher H2 yield (3,283 µmol) at 1 w% of Pt loading

Photon upconversion through triplet exciton-mediated energy relay.

Exploration of upconversion luminescence from lanthanide emitters through energy migration has profound implications for fundamental research and technology development. However, energy migration-mediated upconversion requires stringent experimental conditions, such as high power excitation and special migratory ions in the host lattice, imposing selection constraints on lanthanide emitters. Here we demonstrate photon upconversion of diverse lanthanide emitters by harnessing triplet exciton-mediated energy relay. Compared with gadolinium-based systems, this energy relay is less dependent on excitation power and enhances the emission intensity of Tb3+ by 158-fold. Mechanistic investigations reveal that emission enhancement is attributable to strong coupling between lanthanides and surface molecules, which enables fast triplet generation (<100 ps) and subsequent near-unity triplet transfer efficiency from surface ligands to lanthanides. Moreover, the energy relay approach supports long-distance energy transfer and allows upconversion modulation in microstructures. These findings enhance fundamental understanding of energy transfer at molecule-nanoparticle interfaces and open exciting avenues for developing hybrid, high-performance optical materials

Irradiation of thermal control coatings Final report, Feb. 1967 - Feb. 1968

Irradiation effects on thermal control coatings of OA

Alternative strategies for security labelling/encoding of paper and plastic products.

A literature and patent review of current optical security techniques has been carried out and identified a need in the market for an improved optical security label to rival molecular fluorescent dyes. The label proposed was a rare earth (RE) doped borosilicate glass host that was excited and fluoresced in the visible region. Suitable RE dopants were found to be europium, terbium and dysprosium. The ability to triple dope a single glass and to be able to detect all three dopants based on their discrete fluorescence signals and unique fluorescence lifetimes has been achieved with an in-situ detector. This has advantages over current fluorescent dye labels which have broadband spectra that quickly overlap each other reducing their number of permutations. Energy transfer between the dopants was noted. This can be used to increase the security level as the fluorescence signals were altered by these interactions. Europium was found to be enhanced with the addition of dysprosium or terbium whilst dysprosium enhanced terbium. Environmental studies of the doped glasses were carried out under various extreme conditions. These results concluded that no affect was found on their fluorescence signals or weight. Fluorescence lifetime studies on the single RE doped glasses was successfully carried out. These results were used for the detection system design to increase the selectivity of the RE dopants over background fluorescence. Subsequently an initial single channel detector system was designed and built that could selectively detect 5 mm diameter pieces of 3 mol% europium doped glass. The application of doped glass dispersed in ink and printed onto various media was also successfully demonstrated. With the production of micron sized particles, the glass could be incorporated into a wide variety of media increasing their possible applications in brand protection. Additionally, initial tests for compatibility with the detector system were achieved proving the capabilities of the detector system to detect the doped samples whilst mixed in various media