Quinine doped hybrid sol-gel coatings for wave guiding and optical applications

Pure and quinine doped silica coatings have been prepared over sodalime glasses. The coatings were consolidated at low temperature (range 60-180 A degrees C) preserving optical activity of quinine molecule. We designed a device to test the guiding properties of the coatings. We confirmed with this device that light injected in pure silica coatings is guided over distances of meters while quinine presence induces isotropic photoluminescence. With the combined use of both type of coatings, it is possible to design light guiding devices and illuminate regions in glass elements without electronic circuits.

Evaluación de efectos de biocidas contenidos en recubrimientos “antifouling “(AF coatings) en ecosistemas marinos

De entre los diversos grupos de contaminantes que pueden ser dañinos para ecosistemas acuáticos, sobresalen en los últimos años los biocidas utilizados como principio activo en recubrimientos antifouling ó pinturas anti-incrustantes para cascos de barcos y todo tipo de equipamiento sumergido ó en contacto con agua. Estos recubrimientos se aplican como sistema de protección para combatir la formación y asentamiento de comunidades bioincrustantes (fouling) frente a superficies expuestas al agua, también tienen como finalidad proteger frente a la corrosión de tipo químico y biológico. Normalmente estas pinturas anti-incrustantes son aplicadas en embarcaciones comerciales y de recreo, plataformas petrolíferas, tuberías submarinas, compuertas de presas, instalaciones destinadas a acuicultura, entre otro equipamiento. La utilización de biocidas en la formulación de pinturas anti-incrustantes para barcos ha sido propuesta por muchos investigadores como la aplicación de más impacto para los ecosistemas marinos, debido al intenso tráfico marítimo mundial que provoca la difusión de biocidas contaminantes en los mares, sobre todo en zonas costeras, bahías y puertos que es donde se magnifica el problema. Los llamados recubrimientos antifouling de segunda generación fueron los primeros que emplearon el tributilestaño (TBT) como principio activo en su formulación, a pesar de su gran eficacia y amplia utilización, al cabo del tiempo se ha demostrado su alta toxicidad y persistencia; por lo que existe una gran actividad investigadora en la búsqueda de alternativas asimismo eficientes pero más respetuosas con el medio marino. En este trabajo se pretende comparar los efectos para ecosistemas marinos del TBT y cinco biocidas como son dibutilestaño dicloruro, diuron (diclorofenil dimetil urea), piritionato de Zn ó Zn omadine, óxido de cobre (I) y DCOIT (Dicloro-2-n-octil-4-isotiazol-3-ona). Estos biocidas se han seleccionado en función de su naturaleza química diferenciada, distintas solubilidades en agua, eficacia, ecotoxicidad, persistencia y bioacumulación fundamentalmente. Para proceder a la clasificación del riesgo para ecosistema marino de los biocidas mencionados, nos valdremos de dos metodologías, una será la evaluación de unos índices de riesgo de biocidas para ecosistemas acuáticos con el fin de realizar una clasificación prospectiva de los mismos, basada en criterios PBT (Persistencia, Bioacumulación y Toxicidad para organismos acuáticos) y otra será una evaluación de la razón de la EXPOSICIÓN, valorada como PEC (Predictive Environmental Concentration) con relación a los EFECTOS originados, valorados como PNEC (Predicted No-Effect Concentration). Para cuantificar PEC nos valdremos de modelizaciones para ecosistemas marinos como MAMPEC (Marine Antifoulant Model to Predict Environmental Concentrations). Para cuantificar PNEC se hace uso de bioensayos a corto o largo plazo en organismos acuáticos. De esta manera podremos agrupar los biocidas en diversas categorías de riesgo y así poder decidir cuando su impacto medioambiental es asumible ó no asumible, alternativas posibles y en todo caso que decisiones se deben tomar al respecto.

Spectral BRDF-based determination of proper measurement geometries to characterize color shift of special effect coatings

A reduced set of measurement geometries allows the spectral reflectance of special effect coatings to be predicted for any other geometry. A physical model based on flake-related parameters has been used to determine nonredundant measurement geometries for the complete description of the spectral bidirectional reflectance distribution function (BRDF). The analysis of experimental spectral BRDF was carried out by means of principal component analysis. From this analysis, a set of nine measurement geometries was proposed to characterize special effect coatings. It was shown that, for two different special effect coatings, these geometries provide a good prediction of their complete color shift.

Left-handed metamaterial coatings for subwavelength-resolution imaging

We report on a procedure to improve the resolution of far-field imaging by using a neighboring high-index medium that is coated with a left-handed metamaterial. The resulting plot can also exhibit an enhanced transmission by considering proper conditions to retract backscattering. Based on negative refraction, geometrical aberrations are considered in detail since they may cause a great impact in this sort of diffraction-unlimited imaging by reducing its resolution power. We employ a standard aberration analysis to refine the asymmetric configuration of metamaterial superlenses. We demonstrate that low-order centrosymmetric aberrations can be fully corrected for a given object plane. For subwavelength-resolution imaging, however, high-order aberrations become of relevance, which may be balanced with defocus. Not only the point spread function but also numerical simulations based on the finite-element method support our theoretical analysis, and subwavelength resolution is verified in the image plane.

Color representation and interpretation of special effect coatings

A representation of the color gamut of special effect coatings is proposed and shown for six different samples, whose colors were calculated from spectral bidirectional reflectance distribution function (BRDF) measurements at different geometries. The most important characteristic of the proposed representation is that it allows a straightforward understanding of the color shift to be done both in terms of conventional irradiation and viewing angles and in terms of flake-based parameters. A different line was proposed to assess the color shift of special effect coatings on a*,b*-diagrams: the absorption line. Similar to interference and aspecular lines (constant aspecular and irradiation angles, respectively), an absorption line is the locus of calculated color coordinates from measurement geometries with a fixed bistatic angle. The advantages of using the absorption lines to characterize the contributions to the spectral BRDF of the scattering at the absorption pigments and the reflection at interference pigments for different geometries are shown.

Preparation of homogeneous CNT coatings in insulating capillary tubes by an innovative electrochemically-assisted method

Preparation of homogeneous CNT coatings in insulating silica capillary tubes is carried out by an innovative electrochemically-assisted method in which the driving force for the deposition is the change in pH inside the confined space between the inner electrode and the capillary walls. This method represents a great advancement in the development of CNT coatings following a simple, cost-effective methodology.

Global color estimation of special-effect coatings from measurements by commercially available portable multiangle spectrophotometers

Colors of special-effect coatings have strong dependence on illumination/viewing geometry and an appealing appearance. An open question is to ask about the minimum number of measurement geometries required to completely characterize their observed color shift. A recently published principal components analysis (PCA)-based procedure to estimate the color of special-effect coatings at any geometry from measurements at a reduced set of geometries was tested in this work by using the measurement geometries of commercial portable multiangle spectrophotometers X-Rite MA98, Datacolor FX10, and BYK-mac as reduced sets. The performance of the proposed PCA procedure for the color-shift estimation for these commercial geometries has been examined for 15 special-effect coatings. Our results suggest that for rendering the color appearance of 3D objects covered with special-effect coatings, the color accuracy obtained with this procedure may be sufficient. This is the case especially if geometries of X-Rite MA98 or Datacolor FX10 are used.

Switchable surfactant-assisted carbon nanotube coatings: innovation through pH shift

The inner surface of fused-silica capillaries has been coated with a dense/homogeneous coating of commercial multi-wall carbon nanotubes (MWCNTs) using a stable ink as deposit precursor. Solubilization of the MWCNTs was achieved in water/ethanol/dimethylformamide by the action of a surfactant, which can switch between a neutral or an ionic form depending on the pH of the medium, which thus becomes the driving force for the entire deposition process. Careful control of the experimental conditions has allowed us to selectively deposit CNTs on the inner surface of insulating silica capillaries by a simple, reproducible, and easily adaptable method.

Natural Pectin Polysaccharides as Edible Coatings

The most fashionable trends in food packaging research are targeted towards improvements in food quality and safety by increasing the use of environmentally-friendly materials, ideally those able to be obtained from bio-based resources and presenting biodegradable characteristics. Edible films represent a key area of development in new multifunctional materials by their character and properties to effectively protect food with no waste production. The use of edible films should be considered as a clean and elegant solution to problems related with waste disposal in packaging materials. In particular, pectin has been reported as one of the main raw materials to obtain edible films by its natural abundance, low cost and renewable character. The latest innovations in food packaging by the use of pectin-based edible films are reviewed in this paper, with special focus on the use of pectin as base material for edible coatings. The structure, properties related to the intended use in food packaging and main applications of pectins are herein reported.

Cooperative research and development agreement with Ford Motor Company : environmental damage to automobile coatings.

Mode of access: Internet.

Low friction hull coatings for icebreakers : phase III, technical report /

Prepared by Rensselaer Polytechnic Institute, under contract DOT-CG-61589-A.

Coatings for the protection of low carbon steel at elevated temperatures /

"Metallurgy and Ceramics."

MFPG--the role of coatings in the prevention of mechanical failures : proceedings of the 23rd meeting of the Mechanical Failures Prevention Group, held at the National Bureau of Standards ... October 29-31, 1975 /

"CODEN: XNBSAV."