Polymer films as aroma barriers at different temperatures

Summary The effectiveness of five polymer films as aroma barriers at 5° C, 25° C and 75° C was investigated by determining their permeability, diffusion, and solubility coefficients for aldehyde vapours. Ethylvinyl acetatelaminated polyethene was not a better aldehyde barrier than its unlaminated counterpart. Polyvinyl chloride was found to be an inferior aldehyde barrier at 5° C compared to the other investigated polymers.

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Kunststoff-Filme als Aroma-Barrieren bei verschiedenen Temperaturen

Zusammenfassung Die Wirkung von fünf Kunststoff-Filmen als Aroma-Barrieren wurde bei 5 °C, 25 °C und 75 °C durch die Bestimmung ihrer Permeabilität, Diffusion und Löslichkeitskoeffizienten in bezug auf Aldehyddämpfe untersucht. Polyäthen mit Schichtstoff Äthylvinylacetat war keine bessere Aldehyd-Barriere als seine entsprechenden unlaminierten Filme. PVC hat sich als eine schlechtere Aldehyd-Barriere bei 5 °C im Vergleich zu den anderen untersuchten Polymeren erwiesen.

     

Interaction of self-interstitials with solutes

For a series of solutes in Cu the enthalpy changes of solute self-interstitial binding are derived from isochronal resistivity recovery data of stage II. For solutes in Al reliable conclusions on binding enthalpies can be deduced only from resistivity damage rate measurements. For Cu as solvent both binding enthalpies and spatial ranges of solute interstitial interaction are in fair agreement with theoretical predictions. For Al both quantities are larger by a factor of about ten in experiment than in theory. For other metals various difficulties prevent an evaluation of binding enthalpies.Rutherford backscattering and Mössbauer studies are sensitive to the configuration of solute self-interstitial pairs. From vanishing of detectable configurations upon isochronal annealing binding enthalpies can be derived. The results reported thus far are generally in agreement with the above resistivity results.Field ion microscopy is discussed as a direct observation method for self-interstitials which escaped solute traps and arrived at the tip surface via long range migration.     

Influence of solar zenith angles on observed trends in the NOAA/NASA 8‐km Pathfinder normalized difference vegetation index over the African Sahel

The strong systematic change in solar zenith angles (SZA) due to annual orbital drift of the NOAA satellites has raised the suspicion of the influence of residual illumination on the calibrated normalized difference vegetation index (NDVI) derived from the Pathfinder AVHRR Land (PAL) database. The aim of this work is to analyse if trends in AVHRR NDVI from 1982 to 2000 over the Sahel region in Africa depend on variations in SZA.

The analysis uses both ordinary least squares regression and cointegration to analyse possible linear dependencies between NDVI and SZA on a per satellite basis. Tests for integration and cointegration fail to find any significant evidence for either. This, together with the ability of simple deterministic models to explain primarily SZA constitutes evidence against integration and cointegration, indicating that linear relationships can be examined using ordinary linear regression. Regression gives no consistent relationship between NDVI and SZA and the explanatory power (R ²) of the regression is low (on average 0.08).

However there is some evidence for downward bias in NDVI due to nonlinear interactions between NDVI and SZA when SZA is large (80°) leading to the conclusion that PAL data from the year 2000 should not be used for analyses in these environments.     

Adsorption of Pb and Cd by amine-modified zeolite

Natural zeolites, known for their excellent sorption properties towards metal cations, are widely used for the purification of wastewaters. The selectivity of clinoptilolite, a common zeolite mineral, for Pb is known to be particularly high, whereas its selectivity for Cd is often lower. Extraordinarily high sorption capacities for soft metal cations were observed in the case of thiol-functionalized silica gels and clays. In order to enhance the zeolites' sorption capacity for Cd, we treated natural heteroionic and Na-clinoptilolite in aqueous suspensions with cysteamine and propylamine solutions and investigated the sorption of Cd and Pb to amine-modified zeolite by a series of batch experiments. Stability constants for amine sorption on all zeolite samples at room temperature and 50 degrees C were obtained. Partial dimerization of cysteamine explains the enhanced sorption of this compound. In contrast, amine treatment did not enhance the adsorption capacity or selectivity of the clinoptilolite towards Cd and Pb. Instead, the amounts of adsorbed heavy metals decreased stoichometrically with increasing sorption of cysteamine and propylamine. This reduction can be explained by the blockage of channels by amine molecules and revealed that the modification of zeolites with mercaptoamines does not enhance the sorption capacity of zeolite for Cd and Pb.     

Simultaneous use of time-resolved fluorescence and anti-stokes photoluminescence in a bioaffinity assay

A bioaffinity assay is described where anti-Stokes photoluminescence of inorganic lanthanide phosphors and time-resolved fluorescence of lanthanide chelates are measured from a single microtitration well without any disturbance from these label technologies to each other. Up-converting phosphor (UPC-phosphor) bioconjugate was produced by grinding the commercial, micrometer-sized UPC-phosphors to colloidal, submicrometer-sized phosphor particles and by attaching these phosphors to biomolecules. Experiments were carried out in standard 96-well microtitration plates to determine detection limits, linearity, and cross-talk of UPC-phosphor and europium chelate. In numbers of molecules the lower limits of detection for UPC-phosphor were roughly 3 x 10(3) particles in solution and 1 x 10(4) particles in solid phase, and for europium label same values were 9 x 10(6) and 9 x 10(7) molecules. Linearity of detection was for UPC-phosphor 5 orders of magnitude in solution and over 4 orders of magnitude in solid phase and for europium label over 5 orders of magnitude in solution and over 4 orders of magnitude in solid phase. The cross-talk between the two labels was practically nonexistent. In this study we show that up-converting anti-Stokes photoluminescent phosphors could be employed in bioaffinity assays as very potential labels with significant advantages either alone or together with long-lifetime lanthanide chelates.     

Acute Phase Response as a Biological Mechanism‐of‐Action of (Nano)particle‐Induced Cardiovascular Disease

Inhaled nanoparticles constitute a potential health hazard due to their size‐dependent lung deposition and large surface to mass ratio. Exposure to high levels contributes to the risk of developing respiratory and cardiovascular diseases, as well as of lung cancer. Particle‐induced acute phase response may be an important mechanism of action of particle‐induced cardiovascular disease. Here, the authors review new important scientific evidence showing causal relationships between inhalation of particle and nanomaterials, induction of acute phase response, and risk of cardiovascular disease. Particle‐induced acute phase response provides a means for risk assessment of particle‐induced cardiovascular disease and underscores cardiovascular disease as an occupational disease.