A simple Raman technique to measure the degree of cure in UV curable coatings

The curing behavior of four UV curable clearcoats was examined using spectra from a confocal Raman microscope. The disappearance of the C=C line near 1636 cm⁻¹ provides the signature for the curing of the samples, but quantification of the degree of cure by standard peak-fitting and baseline subtraction methods does not work well because of sample fluorescence, baseline shifts and overlapping peaks. A smoothed second-derivative processing approach overcomes all of these difficulties and provides a simple, fast and objective quantification procedure. Steep cure gradients through the thickness of the clearcoat, due to screening of the bottom of the clearcoat by both the UVA and photoinitiator, were observed. Cure gradients at the top of the clearcoat due to oxygen inhibition were also observed. The most complete cure throughout the film thickness was obtained with a mixture of standard and red-shifted photoinitiators.     

Application of advanced materials for ship construction – Experiences and problems

Within the paper a short overview is given regarding the application of advanced materials in the shipbuilding world. The trends for application of high‐strength structural steel, aluminium alloys and composites as well as their limits and restrictions are mentioned. Specific attention is paid to material and corrosion problems observed in shipbuilding and ships in service. As main topics the application of high‐tensile strength structural steel for ship structural members, for ballast water tanks and the involved corrosion problems, the fatigue resistance and “undermatch” situation of welded aluminium alloys compared to steel as well as the corrosion of composites, i.e. osmosis, are mentioned. New developments of ships, e.g. high‐speed crafts and wigs, are pointed out. Conclusions for further research and development in the material field are drawn. The importance of the inter‐relationships amongst the improved material properties, design and calculation aspects as well as the fabrication technologies are stated.     

Use of zinc selenide and germanium lenses in the SM400/K701 laser cutting system

Abstract

Appreciably higher cutting speeds, narrower cuts and heat affected zones were obtained on laser cutting of thin sheet steel with an SM400/CO₂ high performance laser system in which ZnSe focusing lenses were substituted for the Ge lenses fitted as standard equipment.     

Apportionment of primary and secondary organic aerosols in southern California during the 2005 study of organic aerosols in riverside (SOAR-1)

Ambient sampling was conducted in Riverside, California during the 2005 Study of Organic Aerosols in Riverside to characterize the composition and sources of organic aerosol using a variety of state-of-the-art instrumentation and source apportionmenttechniques. The secondary organic aerosol (SOA) mass is estimated by elemental carbon and carbon monoxide tracer methods, water soluble organic carbon content, chemical mass balance of organic molecular markers, and positive matrix factorization of high-resolution aerosol mass spectrometer data. Estimates obtained from each ofthese methods indicate that the organic fraction in ambient aerosol is overwhelmingly secondary in nature during a period of several weeks with moderate ozone concentrations and that SOA is the single largest component of PM1 aerosol in Riverside. Average SOA/OA contributions of 70-90% were observed during midday periods, whereas minimum SOA contributions of approximately 45% were observed during peak morning traffic periods. These results are contraryto previous estimates of SOAthroughout the Los Angeles Basin which reported that, other than during severe photochemical smog episodes, SOA was lower than primary OA. Possible reasons for these differences are discussed.     

Sorption and manganese-induced oxidative coupling of hydroxylated aromatic compounds by natural geosorbents

The sorption/desorption equilibria and solvent extractabilities of phenol, o-cresol, and p-chlorophenol with respect to natural sorbents having different types of soil organic matter were investigated. Parallel tests in systems amended with birnessite (delta-MnO2), a solid-phase oxidative coupling catalyst, were also conducted. Sorption/desorption isotherms and solvent extraction data reveal that the relative isotherm linearities, desorption hysteresis, and extractabilities of these compounds are related to the geochemical nature of the sorbent organic matter and to the existence of system conditions that promote oxidative coupling reactions. When suitable coupling catalysts are present, soils containing primarily diagenetically "young" and highly amorphous organic matter (e.g., humic materials) are more likely to retain those solutes than are those containing primarily diagenetically "old" and more condensed organic matter (e.g., kerogens). The sorption/desorption properties of the solutes were significantly altered in the presence of birnessite as a result of both cross-coupling reactions with reactive soil organic matter components and self-coupling reactions with each other to form polymeric species. Under appropriate conditions, mineral-catalyzed oxidative coupling may exert a dominant influence on the sorption and transport of hydroxylated aromatic compounds in soil and sediment systems.     

Chemical-bath ZnO buffer layer for CuInS2 thin-film solar cells

ZnO buffer layers were grown by a chemical-bath deposition (CBD) in order to improve the interface quality in p-CuInS₂ based solar cells, to improve the light transmission in the blue wavelength region, but also as an alternative to eliminate the toxic cadmium. The process consists of immersion of different substrates (glass, CIS) in a dilute solution of tetraamminezinc II, [Zn(NH₂)₄]²⁺, complex at 60–95°C. During the growth process, a homogeneous growth mechanism which proceeds by the sedimentation of a mixture of ZnO and Zn(OH)₂ clusters formed in solution, competes with the heterogeneous growth mechanism. The mechanism consists of specific adsorption of a complex Zn(II) followed by a chemical reaction. The last process of growth results in thin, hard, adherent and specularly reflecting films. The characterization of the deposited CBD-ZnO layers was performed by X-ray diffraction (XRD), optical transmittance, scanning electron microscopy, transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The as-deposited films on glass show hexagonal zincite structure with two preferred orientations (1 0 0) and (1 0 1). High optical transmittance up to 80% in the near-infrared and part of the visible region was observed. The low growth rate of the films on CIS suggests an atomic layer-by-layer growth process.The device parameters and performance are compared to heterojunction with a standard CdS buffer layer.     

1.47 /spl mu/m Tm/sup 3+/:ZBLAN fibre laser pumped at 1.064 /spl mu/m

A large core area (1257 /spl mu/m/sup 2/) Tm/sup 3+/-doped ZBLAN fibre laser operated at 1.47 /spl mu/m is demonstrated. The pump source is a Nd:YAG laser operated at 1.064 /spl mu/m. A laser output power of 1.56 W continuous wave was obtained for 5.2 W of launched pump power. The slope efficiency with respect to the launched pump power was measured to be 33%.     

Discounting future green: Money versus the environment.

In 3 studies, participants made choices between hypothetical financial, environmental, and health gains and losses that took effect either immediately or with a delay of 1 or 10 years. In all 3 domains, choices indicated that gains were discounted more than losses. There were no significant differences in the discounting of monetary and environmental outcomes, but health gains were discounted more and health losses were discounted less than gains or losses in the other 2 domains. Correlations between implicit discount rates for these different choices suggest that discount rates are influenced more by the valence of outcomes (gains vs. losses) than by domain (money, environment, or health). Overall, results indicate that when controlling as many factors as possible, at short to medium delays, environmental outcomes are discounted in a similar way to financial outcomes, which is good news for researchers and policy makers alike. (PsycINFO Database Record (c) 2010 APA, all rights reserved)