The net effect of ultraviolet radiation on atmospheric dimethylsulphide over the Southern Indian Ocean

Dimethylsulphide (DMS) in the atmosphere may play an important role in the climate system. This study shows an inverse relationship between ultraviolet extremes and atmospheric DMS, independent of changes in wind speed, sea-surface temperature and photosynthetically active radiation, as measured at Amsterdam Island in the Southern Indian Ocean.     

Mechanical relaxations of poly(vinylidene fluoride) and some of its copolymers

The dynamic mechanical properties of poly(vinylidene fluoride) have been studied under isochronal conditions and the effect of thermal treatment examined. The results are compared with a product of different molecular weight distribution. The study also included the mechanical relaxation spectra of copolymers of vinylidene fluoride and chlorotrifluoroethylene at four compositions and four frequencies as a function of temperature. The thermodynamic parameters associated with the main relaxations were determined and the results discussed on the basis of available information on the drgree of crystallinity, copolymer heterogeneity, and main chain flexibility.     

Viscous and Aeroelastic Effects on Wind Turbine Blades. The VISCEL project. Part I: 3D Navier–Stokes Rotor simulations

Aerodynamic modelling of HAWT rotors by means of “engineering methods” has reached a saddle point, where no further development can be expected without a breakthrough in understanding the physics of unsteady, rotating three‐dimensional flows. However, such a breakthrough becomes ever more necessary, as the size of the wind turbines increases. With the experimental work in that direction being mostly limited to observing the phenomena and interpreting the associated mechanisms, and its increased cost, alternatives are being sought. The use of CFD techniques and state‐of‐the‐art Navier–Stokes solvers is considered a very serious contender, a belief shared by the members of the present consortium, which has worked on the VISCEL JOR3‐CT98‐0208 Joule III project. This project's goal was to determine the aerodynamic characteristics as well as the aeroelastic behaviour of wind turbine blades across their broad range of operational conditions, from attached to highly separated flow regimes. The work programme included specific tasks for the validation and assessment of existing 3D solvers, for the parametric study of 3D flow around realistic blades and for the investigation of aeroelastic stability, at the blade section level. Copyright © 2003 John Wiley & Sons, Ltd.     

A comparative organic geochemical study of oils seeps in Western Greece

Samples from three oil shows in Western Greece were studied following a suite of analytical geochemical procedures, aiming to reveal the origin of the organic matter and characterize its depositional environment. The authors’ findings were compared, and confirmed to a great extent, to geochemical results from previously published studies. Certain compositional differences exist between the three oil shows, reflecting different source rock and/or different facies. The influence of different analytical methodologies commonly used to separate compound groups (saturates, aromatics, resins, asphaltenes) on the obtained geochemical indices was also examined. The results demonstrate that bulk composition of maltenes, as well as most biomarker indices, are not affected significantly by the employed group-type separation procedures.     

Accelerating SPARQL queries by exploiting hash-based locality and adaptive partitioning

State-of-the-art distributed RDF systems partition data across multiple computer nodes (workers). Some systems perform cheap hash partitioning, which may result in expensive query evaluation. Others try to minimize inter-node communication, which requires an expensive data preprocessing phase, leading to a high startup cost. Apriori knowledge of the query workload has also been used to create partitions, which, however, are static and do not adapt to workload changes. In this paper, we propose AdPart, a distributed RDF system, which addresses the shortcomings of previous work. First, AdPart applies lightweight partitioning on the initial data, which distributes triples by hashing on their subjects; this renders its startup overhead low. At the same time, the locality-aware query optimizer of AdPart takes full advantage of the partitioning to (1) support the fully parallel processing of join patterns on subjects and (2) minimize data communication for general queries by applying hash distribution of intermediate results instead of broadcasting, wherever possible. Second, AdPart monitors the data access patterns and dynamically redistributes and replicates the instances of the most frequent ones among workers. As a result, the communication cost for future queries is drastically reduced or even eliminated. To control replication, AdPart implements an eviction policy for the redistributed patterns. Our experiments with synthetic and real data verify that AdPart: (1) starts faster than all existing systems; (2) processes thousands of queries before other systems become online; and (3) gracefully adapts to the query load, being able to evaluate queries on billion-scale RDF data in subseconds.     

Infra-red and Raman spectroscopic study on the thermal stability and high temperature transformation of hydroazafullerene C59HN

Hydroazafullerene C₅₉HN was studied by vibrational infra-red and Raman spectroscopy and its thermal stability was examined. Fingerprints modes were identified and unambiguously differentiate it from bisazafullerene. At 700 K full transformation to bisazafullerene occurred, while an intermediate metastable phase was identified at 540 K showing different spectra where the splitting of most of the lines is strongly reduced.     

Mapping average equivalized income using robust small area methods

Measures of economic well‐being are often needed for geographically small areas, as economic indicators may be distributed unevenly among the subsets of relatively small regions. We consider small area estimation of average equivalized income. Disposable household income data are usually available only for a sample of households, typically too small to provide reliable estimates for small regions. We consider a small area estimation technique that is robust to outliers, produces results consistent with design weighted estimates obtained for larger areas and yield maps with approximately no shrinkage. The proposed methodology is applied to the Local Labour Systems in Tuscany (Italy).     

Biomimetically synthesized silica-carbon nanofiber architectures for the development of highly stable electrochemical biosensor systems

Biomimetically synthesized silica and conductive activated carbon nanofibers (CNFs) are used in a synergistic manner for the development of a novel electrochemical biosensor system. Poly(L-lysine) templated silica grows and encapsulates the CNF-immobilized enzyme generating a highly stabilizing nanostructured environment for the underlying protein. Concurrently, CNFs provide both the required surface area for the high-capacity enzyme immobilization required in biosensors as well as direct electron transfer to the inner platinum transducer. As a result, this silica/nanofiber superstructure is an ideal architecture for the development of electrochemical biosensor systems that can withstand exposure to extreme operational conditions, such as high temperatures or the presence of proteases. Acetylcholine esterase is used as the model catalyst and with the aid of spectroscopic data it is shown that the observed high operational stability of the biosensor is due to the direct interaction of the protein with the silica backbone, as well as due to the nanostructured enzyme confinement.     

Direct evidence for covalent functionalization of carbon nanohorns by high-resolution electron microscopy imaging of C60 conjugated onto their skeleton

Carbon nanohorns (CNHs) functionalized with aryl units, possessing ethylene glycol chains terminated to amine groups, were condensed with modified C₆₀ carrying a free carboxylic acid group. Direct evidence for the covalent functionalization of CNHs was given by high-resolution transmission electron microscopy (HR-TEM) imaging of C₆₀ present in that CNH hybrid material. In addition, it was found that C₆₀ remained unaffected even after prolonged exposure to the electron beam. Finally, monitoring the wave motion of the connecting ethylene glycol chains, through sequential HR-TEM images, further proved the stability of the covalent bond that links the two carbon nanostructures.