Atmospheric transport of sulphur compound pollutants

Imperial Users onl

Influence of structural disorder and large-scale geometric fluctuations on the Coherent Transport of Metallic Junctions and Molecular Wires

Structural disorder is present in almost all experimental measurements of electronic transport through single molecules or molecular wires. To assess its influence on the conductance is computationally demanding, because a large number of conformations must be considered. Here we analyze an approximate recursive layer Green function approach for the ballistic transport through quasi one-dimensional nano-junctions. We find a rapid convergence of the method with its control parameter, the layer thickness, and good agreement with existing experimental and theoretical data. Because the computational effort rises only linearly with system size, this method permits treatment of very large systems. We investigate the conductance of gold- and silver wires of different sizes and conformations. For weak electrode disorder and imperfect coupling between electrode and wire we find conductance variations of approximately 20%. Overall we find the conductance of silver junctions well described by the immediate vicinity of narrowest point in the junction, a result that may explain the observation of well-conserved conductance plateaus in recent experiments on silver junctions. In an application to flexible oligophene wires, we find that strongly distorted conformations that are sterically forbidden at zero temperature, contribute significantly to the observed average zero-bias conductance of the molecular wire

Oceanographic observation of New York Bight from ERTS-1

The author has identified the following significant events. The Earth Resources Technology Satellite made a transit over New York Bight on 16 August, 1972. Imagery from this transit shows several oceanographic features that demonstrate the usefulness of remote sensing for large area, synoptic observation of changes in water quality in the coastal zone. Both the extent and turbulent character of the Hudson River plume are discernible in the image. Residue from a dump of waste acid is visible over a five mile area in the apex of the Bight. Little dispersion of this residue has occurred which suggests that this feature will be a persistent signature in images from future satellite transits

An Experiment to Evaluate Skylab Earth Resources Sensors for Detection of the Gulf Stream

The author has identified the following significant results. An experiment to evaluate the Skylab earth resources package for observing ocean currents was performed in the Straits of Florida in January 1974. Data from the S190 photographic facility, S191 spectroradiometer and S192 multispectral scanner, were compared with surface observations. The anticyclonic edge of the Gulf Stream could be identified in the Skylab S190A and B photographs, but the cyclonic edge was obscured by clouds. The aircraft photographs were judged not useful for spectral analysis because vignetting caused the blue/green ratios to be dependent on the position in the photograph. The spectral measurement technique could not identify the anticyclonic front, but mass of Florida Bay water which was in the process of flowing into the Straits could be identified and classified. Monte Carlo simulations of the visible spectrum showed that the aerosol concentration could be estimated and a correction technique was devised

Study and parentage analysis of old Albanian grapevine cultivars by ampelography and microsatellite markers

The number of old grapevine cultivars in Albania, originated in the country or introduced over many centuries and adapted to the conditions of the country, is huge. Because numerous cases of homonymy and synonymy exist, the interest for variety recognition is high. Investigation of these cultivars aptitudes is related to identification of desired characteristics and their utilization. In the framework of COST Action FA1003, trueness to type assessment of 13 old Albanian cultivars was undertaken including morphologic description and genetic fingerprinting. Parentage relationships were studied as well. The selected cultivars are of interest for their antiquity, for high production and distinctive organoleptic features. The ampelographic study of these cultivars supported confirmation of the results obtained by genetic profile comparison with seven SSR-marker databases and the European Vitis Database. In summary 12 unique genotypes, four parent-offspring relationships and one full parentage were found

The "missing link" 'Blaue Zimmettraube' reveals that 'Blauer Portugieser' and 'Blaufränkisch' originated in Lower Styria

Parent offspring analysis already revealed genetic relationships for 'Blauer Portugieser' and 'Blaufränkisch', sharing at each locus one allele with 'Grüner Silvaner' and 'Weisser Heunisch', respectively. The missing second progenitor of 'Blauer Portugieser' and 'Blaufränkisch' is a recently rediscovered black grapevine, called 'Blaue Zimmettraube'. It was found in the largest German wine growing area Rheinhessen. The same cultivar was detected as a single vine in Friuli, Italy and named Sbulzìna. The 'Blaue Zimmettraube', bearing female flowers, and thus the female parent in the crosses, was cultivated in the 19th century in Lower Styria together with 'Grüner Silvaner' and 'Weisser Heunisch'. Because the 'Blaue Zimmettraube' did not exist in Austria and red wine production was fairly rare in that country before 1800, it is suspected that the cradle of 'Blauer Portugieser' and 'Blaufränkisch' is in Lower Styria. Furthermore, according to chlorotype analysis, it turned out that 'Blauer Gänsfüsser' is the male parent of 'Blaue Zimmettraube' and thus the 'Blaue Zimmettraube' represents a veritable "missing link". To prove the genetic relationships the nine GrapeGen06-markers and additional forty microsatellite markers were applied. Likelihood analysis with allele frequencies of 22 SSR-markers from 772 cultivars revealed a very high degree of probability that the proposed parents are consistent, due to rare alleles inherited from 'Blaue Zimmettraube'. To investigate on the geographical origin of 'Blauer Portugieser' and 'Blaufränkisch' historical Austrian and Styrian references were consulted

The prolific grape variety (Vitis vinifera L.) ‘Heunisch Weiss’ (= ‘Gouais blanc’): bud mutants, “colored” homonyms and further offspring

‘Heunisch Weiss’ (syn. ‘Gouais blanc’) contributed to a considerable increase of our varietal assortment, including renowned varieties like ‘Chardonnay’ and ‘Riesling Weiss’. Three phenotypic variants of ‘Heunisch Weiss’ were discovered in the grapevine collection at the JKI Institute for Grapevine Breeding Geilweilerhof: (a) ‘Heunisch Dreifarbig’ (three coloured ‘Heunisch’; VIVC prime name ‘Heunisch Dreifarbig’) expressing intense anthocyanin coloration on shoots, inflorescences and leaf petioles before fruit set and even red berry skin at fruit set stage; (b) ‘Pekasore’ (VIVC prime name ‘Heunisch Rotgestreift’; red striped ‘Heunisch’;) with rose to red stripes on white berries and (c) the stenospermocarpic ‘Aspirant’ (VIVC prime name ‘Heunisch Weiss Seedless’). Four cultivars proving to be homonymous in relation to ‘Heunisch’ were investigated at 24 loci to determine their identity or relatedness to ‘Heunisch Weiss’, respectively. ‘Heunisch Schwarz’ turned out to be a ‘Heunisch Weiss’ offspring. No parent offspring relationship was detected for ‘Heunisch Rot’, ‘Haenisch Rot’ = ‘Pamid’, and ‘Heunisch Blau’ . Ampelographic description was carried out for some of the accessions to trace back historical evidences. In addition five new ‘Heunisch Weiss’ offsprings were identified and confirmed by analysing 35 nuclear microsatellite loci. The accession ‘Furmint Apiren’ turned out to be a seedless bud mutant of the ‘Heunisch Weiss’ offspring ‘Iordan’

Pre-selectable integer quantum conductance of electrochemically fabricated silver point contacts

The controlled fabrication of well-ordered atomic-scale metallic contacts is of great interest: it is expected that the experimentally observed high percentage of point contacts with a conductance at non-integer multiples of the conductance quantum G_0 = 2e^2/h in simple metals is correlated to defects resulting from the fabrication process. Here we demonstrate a combined electrochemical deposition and annealing method which allows the controlled fabrication of point contacts with pre-selectable integer quantum conductance. The resulting conductance measurements on silver point contacts are compared with tight-binding-like conductance calculations of modeled idealized junction geometries between two silver crystals with a predefined number of contact atoms

Assessing Thermochemical Properties of Materials through Ab initio Quantum-mechanical Methods: The Case of α-Al2O3

The thermochemical behavior of α-Al2O3 corundum in the whole temperature range 0–2317 K (melting point) and under pressures up to 12 GPa is predicted by applying ab initio methods based on the density functional theory (DFT), the use of a local basis set and periodic-boundary conditions. Thermodynamic properties are treated both within and beyond the harmonic approximation to the lattice potential. In particular, a recent implementation of the quasi-harmonic approximation, in the Crystal program, is here shown to provide a reliable description of the thermal expansion coefficient, entropy, constant-volume and constant-pressure specific heats, and temperature dependence of the bulk modulus, nearly up to the corundum melting temperature. This is a remarkable outcome suggesting α-Al2O3 to be an almost perfect quasi-harmonic crystal. The effect of using different computational parameters and DFT functionals belonging to different levels of approximations on the accuracy of the thermal properties is tested, providing a reference for further studies involving alumina polymorphs and, more generally, quasi-ionic minerals