Volatile organic compounds in rural atmospheres of central Portugal

Atmospheric concentrations of volatile organic compounds were measured at two rural sites in central Portugal. The sites were chosen to be in line with the summer northwesterly sea breezes in order to study the evolution of the chemical composition of air masses during transport to inland areas. The most abundant non-oxygenated hydrocarbon in the ambient air was isoprene and the monoterpenes alpha-pinene, beta-pinene and 1,8 cineol. The maximum isoprene levels (6-7 ppb) were recorded at the most inland site, suggesting an enrichment of coastal air masses with biogenic emissions during transport over eucalyptus forests. Formaldehyde was the most prominent carbonyl compound in the atmosphere but acetaldehyde and acrolein were also abundant. Concentrations of carbonyl compounds had a tendency to be higher inland, particularly for glyoxal, methyl glyoxal, methyl vinyl ketone, metacrolein and pentanal. The observed increases indicate that carbonyls were produced by photochemical oxidation of biogenic hydrocarbons in aged air masses with coastal origin. Isoprene, monoterpenes and various carbonyls exhibited pronounced diurnal variations, which are explained on the basis of emissions from vegetation, oxidation pathways of biogenic hydrocarbons and meteorological conditions.     

Development of molecular hydrogen-bonding potentials (MHBPs) and their application to structure-permeation relations

Hydrogen bonds are major forces of recognition in biochemistry and molecular pharmacology; they are an essential component of intermolecular interactions and determine to a significant extent the 3D-structure of bio-macromolecules. To explore three-dimensional H-bonding properties, a new tool called Molecular Hydrogen-Bonding Potentials (MHBPs) was created. The development of this tool is based on a stepwise procedure similar to the one used successfully to generate the Molecular Lipophilicity Potential (MLP). First, a H-bonding fragmental system was developed starting from published solvatochromic parameters. An atomic H-bonding donor fragmental value (alpha) is associated to each hydrogen atom in a polar moiety. Similarly, an atomic H-bonding acceptor fragmental value (beta) is associated to each polar atom. A distance function and an angle function were defined to take into account variations of the MHBPs in space. The fragmental system and the geometric functions were then combined to generate the MHBPs. These are calculated at each point of an adequate molecular surface or on a three-dimensional grid. The MHBPs were compared with GRID interactions energies and correlated with success to oral drug absorption data. Available examples demonstrate that the MHBPs are a promising computational tool in drug design. Their combination with CoMFA and VolSurf is being studied.     

Telehealth: 'real life' implementation issues

This paper addresses the practical issues specific to the successful integration of telehealth into the Canadian health system at national, regional, provincial and territorial levels. Five key issues for optimal implementation were readiness of the environment; needs analysis/strategic business plans/diverse partnerships; equipment and Information Technology (IT) vendors; staged implementation; and evaluation. Strong professional, as well as technical policy standards, were also required. Recognizing the importance of human factors and workforce implications, the change process, and the changing culture were also viewed as critical to successful implementation. The importance of 'best practices', 'lessons learned', 'buy-in', inter-connectivity, inter-operability, and sustainability issues was noted. Lastly, ongoing systemic evaluation was seen to be key to sustained telehealth programs.     

Quasi-elastic light scattering for intermittent dynamics

Dynamic light-scattering techniques provide noninvasive probes of diverse media such as colloidal suspensions, granular materials, and foams. Traditional analysis relies on the Gaussian properties of the scattering process found in most experimental situations and uses second-order intensity-correlation functions. This approach fails in the presence of, among other things, the collective intermittent dynamics found in systems such as granular materials. By extending the existing formalism and introducing higher-order intensity-correlation functions, we show how to detect and quantify the intrinsic dynamics and switching statistics of intermittent processes. We then explore two systems: (1) an auger-driven granular column for which the granular dynamics are controlled and the formalism is tested and (2) a granular heap whose dynamics are a priori unknown but may, now, be characterized.     

A thermoluminescence dosimetry system for personal monitoring in Ireland

In 1993 the decision was taken to replace film badges with thermoluminescence dosemeters (TLDs) as the main form of dosemeter for both whole-body and extremity monitoring at the Dosimetry Service of the Radiological Protection Institute of Ireland (RPII) in Dublin. A review of commercially available automatic TLD systems was carried out to identify the system which best met the RPII's requirements. This paper describes the dosimetry system used, and, in addition, discusses the problems encountered and how these were addressed.     

Trace metal accumulation in Clarias gariepinus (Teugels) exposed to sublethal levels of tannery effluent

The concentration and distribution of Cr, Cu, Pb and Zn among the tissues of a freshwater fish, Clarias gariepinus exposed to combined (composite) tannery effluent was investigated at two sublethal concentrations (2 and 6%) in static bioassay for 8 weeks. The distribution of the four metals in fish was of the order of Pb > Cr > Cu > Zn and the accumulation was found to be dose- and time-dependent. The metal levels in the liver were significantly higher (P > 0.05) than other tissues. This was followed by the gill and the gut. Relatively low accumulation of these metals was found in muscle tissue.     

Contrast-enhancement techniques for particle-image velocimetry

In video-based particle-image velocimetry (PIV) systems for fluid mechanics research, it is sometimes desirable to image seed particles to be smaller than a camera pixel. However, imaging to this size can lead to marginal image contrast such that significant numbers of erroneous velocity vectors can be computed, even for simple flow fields. A variety of image-enhancement techniques suitable for a low-cost PIV system that uses video cameras are examined and tested on three representative flows. Techniques such as linear contrast enhancement and histogram hyperbolization are shown to have good potential for improving the image contrast and hence the accuracy of the data-reduction process with only a 15% increase in the computational time. Some other schemes that were examined appear to be of little practical value in PIV applications. An automated shifting algorithm based on mass conservation is shown to be useful for displacing the second interrogation region in the direction of flow, which minimizes the number of uncorrelated particle images that contribute noise to the data-reduction process.     

石英砂岩孔隙度预测与时间、温度、深度、缝合面密度和含烃饱和度的关系

1前言砂岩孔隙度演化是地史时期中物理和化学变化的结果。控制沉积盆地砂岩孔隙度的特性包括矿物学、结构、压力、温度及埋藏史。为了评价砂岩油藏的储量，地质工作者已做了大量孔隙度和基本属性间关系的工作，主要以孔隙度与一个或多个单变量间的经验相关性为基础。由于相关性并无因果关系，放这些相关性仅限于应用到特定盆地、岩石单元或深度范围，当推广至其他地方将导致许多不确定性。为了克服这些限制，许多研究人员试图弄清孔隙演化过程中的物理和化学变化。他们大多假定石英胶结物来源于大量富二氧化硅流体的注入或压力分解作用。但…