Marginal External Costs of Peak and Non Peak Urban Transport in Belgium

This paper discusses intermediate results of an ongoing research project to estimate all external costs from all transport modes in Belgium. It gives estimates of the marginal external costs of air pollution from urban transport. The evaluation of the environmental impacts is based on the European ExternE accounting framework. This methodology uses the impact pathway analysis for the detailed bottom-up assessment of impacts from air pollutants. It integrates state of the art knowledge in the fields of emission modelling, dispersion modelling, dose-response functions and monetary valuation. This paper focuses on the impact of location (rural areas versus cities), regulation, traffic conditions and congestion on environmental externalities. These case studies for Belgium confirm earlier results of the ExternE project that external environmental costs of car transport are significant and that damage to public health is the dominant impact. In addition, it shows that externalities of urban peak traffic are 2 to 4 times higher than for normal urban driving conditions. Finally, it calculates which occupancy rates are required for urban public transport (trams and diesel buses) to have lower external costs compared to passenger cars.Externalities, Urban transport, Air pollution, Congestion, Sustainable mobility

Marginal External Costs of Peak and Non Peak Urban Transport in Belgium

This paper discusses intermediate results of an ongoing research project to estimate all external costs from all transport modes in Belgium. It gives estimates of the marginal external costs of air pollution from urban transport. The evaluation of the environmental impacts is based on the European ExternE accounting framework. This methodology uses the impact pathway analysis for the detailed bottom-up assessment of impacts from air pollutants. It integrates state of the art knowledge in the fields of emission modelling, dispersion modelling, dose-response functions and monetary valuation. This paper focuses on the impact of location (rural areas versus cities), regulation, traffic conditions and congestion on environmental externalities. These case studies for Belgium confirm earlier results of the ExternE project that external environmental costs of car transport are significant and that damage to public health is the dominant impact. In addition, it shows that externalities of urban peak traffic are 2 to 4 times higher than for normal urban driving conditions. Finally, it calculates which occupancy rates are required for urban public transport (trams and diesel buses) to have lower external costs compared to passenger cars

Surface Enhancement of Superconductivity in Tin

The possibility of surface enhancement of superconductivity is examined experimentally. It is shown that single crystal tin samples with cold-worked surfaces represent a superconductor with a surface-enhanced order parameter (or negative surface extrapolation length b), whose magnitude can be controlled.Comment: 8 pages, 4 figure

Expression of renal distal tubule transporters TRPM6 and NCC in a rat model of cyclosporine nephrotoxicity and effect of EGF treatment

Renal magnesium (Mg(2+)) and sodium (Na(+)) loss are well-known side effects of cyclosporine (CsA) treatment in humans, but the underlying mechanisms still remain unclear. Recently, it was shown that epidermal growth factor (EGF) stimulates Mg(2+) reabsorption in the distal convoluted tubule (DCT) via TRPM6 (Thebault S, Alexander RT, Tiel Groenestege WM, Hoenderop JG, Bindels RJ. J Am Soc Nephrol 20: 78-85, 2009). In the DCT, the final adjustment of renal sodium excretion is regulated by the thiazide-sensitive Na(+)-Cl(-) cotransporter (NCC), which is activated by the renin-angiotensin-aldosterone system (RAAS). The aim of this study was to gain more insight into the molecular mechanisms of CsA-induced hypomagnesemia and hyponatremia. Therefore, the renal expression of TRPM6, TRPM7, EGF, EGF receptor, claudin-16, claudin-19, and the NCC, and the effect of the RAAS on NCC expression, were analyzed in vivo in a rat model of CsA nephrotoxicity. Also, the effect of EGF administration on these parameters was studied. CsA significantly decreased the renal expression of TRPM6, TRPM7, NCC, and EGF, but not that of claudin-16 and claudin-19. Serum aldosterone was significantly lower in CsA-treated rats. In control rats treated with EGF, an increased renal expression of TRPM6 together with a decreased fractional excretion of Mg(2+) (FE Mg(2+)) was demonstrated. EGF did not show this beneficial effect on TRPM6 and FE Mg(2+) in CsA-treated rats. These data suggest that CsA treatment affects Mg(2+) homeostasis via the downregulation of TRPM6 in the DCT. Furthermore, CsA downregulates the NCC in the DCT, associated with an inactivation of the RAAS, resulting in renal sodium loss

Global regulation of gene expression by OxyR in an important human opportunistic pathogen

Most bacteria control oxidative stress through the H2O2-responsive transactivator OxyR, a member of the LTTR family (LysR Type Transcriptional Regulators), which activates the expression of defensive genes such as those encoding catalases, alkyl hydroperoxide reductases and superoxide dismutases. In the human opportunistic pathogen Pseudomonas aeruginosa, OxyR positively regulates expression of the oxidative stress response genes katA, katB, ahpB and ahpCF. To identify additional targets of OxyR in P. aeruginosa PAO1, we performed chromatin immunoprecipitation in combination with whole genome tiling array analyses (ChIP-chip). We detected 56 genes including all the previously identified defensive genes and a battery of novel direct targets of OxyR. Electrophoretic mobility shift assays (EMSAs) for selected newly identified targets indicated that ∼70% of those were bound by purified oxidized OxyR and their regulation was confirmed by quantitative real-time polymerase chain reaction. Furthermore, a thioredoxin system was identified to enzymatically reduce OxyR under oxidative stress. Functional classification analysis showed that OxyR controls a core regulon of oxidative stress defensive genes, and other genes involved in regulation of iron homeostasis (pvdS), quorum-sensing (rsaL), protein synthesis (rpsL) and oxidative phosphorylation (cyoA and snr1). Collectively, our results indicate that OxyR is involved in oxidative stress defense and regulates other aspects of cellular metabolism as well

Candida albicans-produced farnesol stimulates Pseudomonas quinolone signal production in LasR-defective Pseudomonas aeruginosa strains

Candida albicans has been previously shown to stimulate the production of Pseudomonas aeruginosa phenazine toxins in dual-species colony biofilms. Here, we report that P. aeruginosa lasR mutants, which lack the master quorum sensing system regulator, regain the ability to produce quorum-sensing-regulated phenazines when cultured with C. albicans. Farnesol, a signalling molecule produced by C. albicans, was sufficient to stimulate phenazine production in LasR− laboratory strains and clinical isolates. P. aeruginosa ΔlasR mutants are defective in production of the Pseudomonas quinolone signal (PQS) due to their inability to properly induce pqsH, which encodes the enzyme necessary for the last step in PQS biosynthesis. We show that expression of pqsH in a ΔlasR strain was sufficient to restore PQS production, and that farnesol restored pqsH expression in ΔlasR mutants. The farnesol-mediated increase in pqsH required RhlR, a transcriptional regulator downstream of LasR, and farnesol led to higher levels of N-butyryl-homoserine lactone, the small molecule activator of RhlR. Farnesol promotes the production of reactive oxygen species (ROS) in a variety of species. Because the antioxidant N-acetylcysteine suppressed farnesol-induced RhlR activity in LasR− strains, and hydrogen peroxide was sufficient to restore PQS production in las mutants, we propose that ROS are responsible for the activation of downstream portions of this quorum sensing pathway. LasR mutants frequently arise in the lungs of patients chronically infected with P. aeruginosa. The finding that C. albicans, farnesol or ROS stimulate virulence factor production in lasR strains provides new insight into the virulence potential of these strains

Vortex pinning in superconductors laterally modulated by nanoscale self-assembled arrays

In this work we studied the possibility of using nanoscale self-assembled arrays as templates to achieve periodic nanomodulation in superconducting thin films and their vortex pinning properties. The first system that was investigated was the periodic surface of a colloidal crystal grown by convective self-assembly of spherical colloidal polystyrene (PS) particles on SiO2. The top layer of the crystal consists of a closely packed (= triangular) array of nanospheres on which thin Nb films were grown. We studied crystals of nanospheres with a different diameter i.e. 357 nm and 202 nm. The Nb film thickness turned out to be crucial for achieving a reasonable level of electrical conduction in the weakly linked Nb "net" on top of the colloidal crystal. In the case of the 357 PS colloidal crystal covered with 130 nm Nb, we established the existence of a honeycomb potential of pinning centers which can be associated with the voids between the colloidal particles. The H – T phase diagram and resistance measurements indicate that this system behaves as a superconducting network, giving rise to integer and non-integer matching effects between the vortex lattice and the colloidal void lattice in magnetic fields up to 72 mT. However, the 202 nm PS colloidal crystal covered with 70 nm Nb shows that the nanosphere diameter clearly controls the vortex pinning properties of the colloidal crystal surface. Here, the resistance measurements only reveal weak pinning effects which are not entirely-field stable, apart from one single strongly pinned phase. The H – T phase diagram suggests the weak pinning to originate from purely geometric ordering effects due to competing symmetries in the colloidal lattice. Nevertheless, by using colloidal crystals of sufficiently large diameter, it is possible to observe periodic matching effects in magnetic fields covering the entire 100 G range. Currently, we are investigating the possibility of using macroscopically ordered monolayers of PS nanopsheres (monolayer) as etching mask to produce periodic pinning arrays in Nb thin film substrates (and magnetic films) and to study the effect of the nanosphere diameter on vortex pinning by magnetization and transport measurements. Futhermore, the use of neutron scattering is targetted for the study of the evolution of the vortex lattice symmetry with magnetic field in these structures. The second system that was investigated was the surface of anodized Al2O3 (AAO), which is essentially a membrane of triangularly arranged parallel hollow channels. AAO templates with different channel spacing and diameter were prepared; their surface was covered with 50 nm Nb. The superconductor mimics the periodic surface features, resulting in a Nb thin film with a triangular array of porous defects. We were able to analyze the vortex pinning properties of these system in the framework of the research conducted on lithographic antidot lattices. In the case of the template with 100 nm period and a pore diameter of 40 nm, the H – T phase diagram obtained from transport measurements indicates the existence of integer matching effects in fields up to 700 mT. The magnetization measurements showed that the "porous" antidots to act as efficient pinning centers, providing strongly increased critical currents compared to the plain reference film. Therefore, the triangular porous lattice can be labeled as a triangular lattice of "porous antidots". The second template with 50 nm period and a pore diameter of 25 nm suffered from a decrease in local order, but showed a single strong matching peak at a magnetic field close to 1T. AAO templated Nb thin films can provide enhanced critical currents and periodic matching effects in magnetic fields covering the entire 1000 G range. A practical application of nanoporous Al2O3 might be its incorporation into wires and cables as a template – matrix for Nb3Sn in the construction of high-field magnets. Recently, our interest in AAO membranes shifted partially away from the membrane surface towards the membrane itself. First, we are investigating the possibility to grow thin, long magnetic nanowires with local monopole character as a PPA system for AAO templated Nb thin films. Secondly, we are investigating the possibility to take advantage of the membrane porosity of AAO by using it as a directing or channeling guide for (superconducting or magnetic) ions to create arrays of size-dependent clusters in a host substrate. In conclusion, the analysis of the colloidal and AAO templates as topographic modulators has clearly shown that the notion and importance of the antidot in the context of superconductivity can be extended to non-lithographic, less ideal systems. Nanoscale self-assembled surfaces have evidenced to provide lateral nanostructuring which allows controlling and manipulating up to a certain degree vortex motion and critical currents in superconducting thin films. In the case of AAO, the template effect has shown to provide efficient pinning centra in a large range of temperature and magnetic field. The potential of self-assembly is not limited to the functionality produced by the surface of its structures, but can reasonably be expected to be further integrated in the solid state research on nanostructures.Introduction 1 1. Theory 5 1.1. Introduction to superconductivity 5 1.1.1. Historical overview 5 1.1.2. Type-I vs. type-II superconductors 12 1.1.3. The vortex lattice in type-II superconductor 18 1.1.4. Thin superconducting films in perpendicular applied field 30 1.2. Introduction to self-assembly 33 1.2.1. What is self-assembly? 33 1.2.2. Some examples 35 2. Experimental techniques 39 2.1. Thin film preparation 39 2.2. Sample characterization 42 2.2.1. X-ray diffraction 42 2.2.2. Scanning electron microscopy 45 2.2.3. Atomic force microscopy 46 2.3. Measurement techniques 49 2.3.1. SQUID magnetometry 49 2.3.2. VSM magnetometry 51 2.3.3. Electrical transport measurements 53 3.Vortex pinning in Nb thin films modulated by colloidal crystals of polystyrene nanospheres 57 3.1. Colloidal self-assembly 58 3.2. Preparation and structural characterization 64 3.2.1. Scanning electron microscopy (SEM) 67 3.2.2. Atomic force microscopy (AFM) 69 3.2.3. Preparation of Nb/colloidal bilayered structures for transport measurements 71 3.3. Vortex pinning properties of the 357nm PS/Nb structure 72 3.3.1. The Hc2(T) phase boundary of the 357 nm PS/Nb structure 73 3.3.2. The periodic pinning potential created by the colloidal array 77 3.3.3. Stable vortex patterns in a superconductor with a honeycomb pinning 79 array of colloidal voids 3.4. Vortex pinning properties of the 202 nm PS/Nb structure 89 3.4.1. The Tc(H) phase boundary of the 202 nm PS/Nb structure 90 3.4.2. Vortex pinning in the 202 nm PS/Nb structure studied by R(H) measurements 91 3.5. Summary 95 4. Vortex pinning in porous Nb arrays created From alumina templates 97 4.1. Anodically prepared Al2O3 films 99 4.1.1. Context 99 4.1.2. Preparation of the anodic Al2O3 templates 102 4.1.3. Structural characterization of the anodic Al2O3 templates 105 4.2. Vortex pinning in AAO1 modulated Nb thin films 110 4.2.1. Preparation and structural characterization 110 4.2.2. Vortex pinning studied by transport measurements 113 4.2.3. Vortex pinning studied by magnetization measurements 121 4.3. Vortex pinning in AAO2 modulated Nb thin films 135 4.3.1. Preparation and structural characterization 135 4.3.2. Vortex pinning studied by magnetization measurements 137 4.4. Summary 140 Conclusions & Outlook 143 Nederlandse samenvatting 147 Bibliography 157 Publications 169 Curriculum Vitae 171status: publishe