Verduurzaming voedselproductie : transportbewegingen van het Nederlandse voedsel

Beschreven is welke transportbewegingen het Nederlandse voedsel maakt, de plaatsen van bestemming, de manieren van transport, de omvang en wijze van het transport van levende dieren en de milieudruk die het transport oplevert

Single-channel transmission in gold one-atom contacts and chains

We induce superconductivity by proximity effect in thin layers of gold and study the number of conduction channels which contribute to the current in one-atom contacts and atomic wires. The atomic contacts and wires are fabricated with a Scanning Tunneling Microscope. The set of transmission probabilities of the conduction channels is obtained from the analysis of the $I(V)$ characteristic curve which is highly non-linear due to multiple Andreev reflections. In agreement with theoretical calculations we find that there is only one channel which is almost completely open.Comment: 4 pages, 2 figures. To be published in Phys. Rev. B, Rapid Communications (2003

Positionering Greenports in de Nederlandse verssector. Productie, import en export van de Nederlandse verssector met een specificering van de Greenport positie

Dit rapport bevat de resultaten van de bijdrage van Wageningen UR Food & Biobased Research aan het project Toegevoegde waarde Netwerk Greenports en Mainports. Het doel van dat project was: ‘Hoe kan een verbindend logistiek netwerk de positie van zowel de Greenports in Nederland als die van de Mainports versterken?

Towards unified understanding of conductance of stretched monatomic contacts

When monatomic contacts are stretched, their conductance behaves in qualitatively different ways depending on their constituent atomic elements. Under a single assumption of resonance formation, we show that various conductance behavior can be understood in a unified way in terms of the response of the resonance to stretching. This analysis clarifies the crucial roles played by the number of valence electrons, charge neutrality, and orbital shapes.Comment: 2 figure

Gemeenschappelijke visie op het VersKernNetwerk van (inter)nationale verbindingen en multimodale knooppunten voor en met de topsectoren Logistiek, Tuinbouw en Agrofood

Het Ministerie van Economische Zaken, Landbouw & Innovatie (EL&I) wil een gezamenlijke visie ontwikkelen op (inter)nationale vers stromen. Hiertoe heeft zij Wageningen UR Food & Biobased Research (FBR), opdracht verleent dit onderzoek uit te voeren. FBR is hoofdaannemer en werkt in dit onderzoek samen met het Landbouw Economisch Instituut (LEI) Wageningen UR. De doelstelling luidt:Komen tot een gemeenschappelijke visie op het VersKernNetwerk van (inter)nationale verbindingen en multimodale knooppunten voor en met de topsectoren Logistiek, Tuinbouw & Uitgangsmaterialen en Agrofood

Quantum transport through STM-lifted single PTCDA molecules

Using a scanning tunneling microscope we have measured the quantum conductance through a PTCDA molecule for different configurations of the tip-molecule-surface junction. A peculiar conductance resonance arises at the Fermi level for certain tip to surface distances. We have relaxed the molecular junction coordinates and calculated transport by means of the Landauer/Keldysh approach. The zero bias transmission calculated for fixed tip positions in lateral dimensions but different tip substrate distances show a clear shift and sharpening of the molecular chemisorption level on increasing the STM-surface distance, in agreement with experiment.Comment: accepted for publication in Applied Physics

First-principles Simulations of the stretching and final breaking of Al nanowires: Mechanical properties and electrical conductance

The evolution of the structure and conductance of an Al nanowire subject to a tensile stress has been studied by first-principles total-energy simulations. Our calculations show the correlation between discontinuous changes in the force (associated to changes in the bonding structure of the nanowire) and abrupt modifications of the conductance as the nanowire develops a thinner neck, in agreement with the experiments. We reproduce the characteristic increase of the conductance in the last plateau, reaching a value close to the conductance quantum $G_0 = 2 e^2 / h$ before the breaking of the nanowire. A dimer defines the contact geometry at these last stages, with three channels (one dominant) contributing to the conductance.Comment: 4 pages, 4 figure

A first-principles approach to electrical transport in atomic-scale nanostructures

We present a first-principles numerical implementation of Landauer formalism for electrical transport in nanostructures characterized down to the atomic level. The novelty and interest of our method lies essentially on two facts. First of all, it makes use of the versatile Gaussian98 code, which is widely used within the quantum chemistry community. Secondly, it incorporates the semi-infinite electrodes in a very generic and efficient way by means of Bethe lattices. We name this method the Gaussian Embedded Cluster Method (GECM). In order to make contact with other proposed implementations, we illustrate our technique by calculating the conductance in some well-studied systems such as metallic (Al and Au) nanocontacts and C-atom chains connected to metallic (Al and Au) electrodes. In the case of Al nanocontacts the conductance turns out to be quite dependent on the detailed atomic arrangement. On the contrary, the conductance in Au nanocontacts presents quite universal features. In the case of C chains, where the self-consistency guarantees the local charge transfer and the correct alignment of the molecular and electrode levels, we find that the conductance oscillates with the number of atoms in the chain regardless of the type of electrode. However, for short chains and Al electrodes the even-odd periodicity is reversed at equilibrium bond distances.Comment: 14 pages, two-column format, submitted to PR