Tension, rigidity and preferential curvature of interfaces between coexisting polymer solutions

The properties of the interface in a phase-separated solution of polymers with different degrees of polymerization and Kuhn segment lengths are calculated. The starting point is the planar interface, the profile of which is calculated in the so-called 'blob model', which incorporates the solvent in an implicit way. The next step is the study of a metastable droplet phase formed by imposing a chemical potential different from that at coexistence. The pressure difference across the curved interface, which corresponds to this higher chemical potential, is used to calculate the curvature properties of the droplet. Interfacial tensions, Tolman lengths and rigidities are calculated and used for predictions for a realistic experimental case. The results suggest that interfaces between phase-separated solutions of polymers exhibit, in general, a preferential curvature, which stabilizes droplets of low molecular mass polymer in a high molecular mass macroscopic phase.Comment: 21 pages; 8 figures; accepted for publication in Macromolecule

Efficiënte keten: Preventie van reststromen: Rapportage 2017/2018

Deze rapportage heeft betrekking op de eerste twee onderzoeksjaren van het publiek-private samenwerking (PPS) project ‘Efficiënte keten, preventie reststromen’ (2017/2018). De ambitie van dit PPS-project is om derving (verspilling) in de biologische agrifood-keten te voorkomen, en daar waar reststromen ontstaan de kansen voor het vermarkten van deze reststromen te vergroten. Binnen dit PPS-project is sprake van twee onderzoekslijnen. Onderzoekslijn A richt zich op de preventie van derving in biologische winkels, en van de derving bij de primaire producenten. Onderzoekslijn B richt zich op het vermarkten van reststromen uit de biologische aardappelen, groenten en fruit (agf) keten, in eerste instantie van producten die afwijkend zijn qua vorm en grootte en om die reden worden afgekeurd voor verkoop via de gebruikelijke afzetkanalen. Bedrijfspartners binnen de PPS ‘Efficiënte keten, preventie reststromen’ zijn Udea/Ekoplaza, Eosta, Odin/Estafette en Green Organics. De kennispartners zijn Wageningen Food & Biobased Research en het Louis Bolk Instituut. Het doel van het PPS project is: te komen tot handvatten voor het tegengaan van derving bij primaire producenten en het voorkomen van derving in de winkels het ontwikkelen van een vermarktingsstrategie voor afwijkende agf-producten en daarmee het verminderen van reststromen uit de agf-keten, en het onderzoeken van andere mogelijkheden van het verwaarden van deze reststromen. Voor de winkelsituatie is met een simulatiemodel geprobeerd om de gemeten derving van drie geselecteerde producten in een voorbeeldwinkel te reconstrueren. Dit leidt tot productspecifieke aanbevelingen met betrekking tot onder meer het verlengen van de houdbaarheid, de presentatievoorraad en het afremmen van het selectiegedrag van de consument. Het uitvalpercentage van ca. 15-25% in de biologische primaire productie (toeleveranciers) blijkt als volgt onderverdeeld: 10-15% uitval van planten 5-10% niet-geoogst product 2% schade/verlies tijdens verpakken e.d. Belangrijke thema’s bij het terugdringen van derving bij toeleveranciers zijn verbinding in de keten, het vertellen van het verhaal naar de klant, handelsnormen en praktische verbeteringen. In het derde jaar van het project zullen voor de winkelsituatie pilots worden opgestart met betrekking tot houdbaarheidsverlenging en het inschatten van het effect van promotieacties. Ook is er een pilot voorzien tussen Eosta en Udea / Ekoplaza (‘Elastische Keten’) ten behoeve van structurele vermindering van productuitval bij Eosta

Rainfall threshold for hillslope outflow: an emergent property of flow pathway connectivity

Nonlinear relations between rain input and hillslope outflow are common observations in hillslope hydrology field studies. In this paper we use percolation theory to model the threshold relationship between rainfall amount and outflow and show that this nonlinear relationship may arise from simple linear processes at the smaller scale. When the rainfall amount exceeds a threshold value, the underlying elements become connected and water flows out of the base of the hillslope. The percolation approach shows how random variations in storage capacity and connectivity at the small spatial scale cause a threshold relationship between rainstorm amount and hillslope outflow. <br><br> As a test case, we applied percolation theory to the well characterized experimental hillslope at the Panola Mountain Research Watershed. Analysing the measured rainstorm events and the subsurface stormflow with percolation theory, we could determine the effect of bedrock permeability, spatial distribution of soil properties and initial water content within the hillslope. The measured variation in the relationship between rainstorm amount and subsurface flow could be reproduced by modelling the initial moisture deficit, the loss of free water to the bedrock, the limited size of the system and the connectivity that is a function of bedrock topography and existence of macropores. The values of the model parameters were in agreement with measured values of soil depth distribution and water saturation

Electronic characterization of redox (non)-innocent Fe2S2 reference systems:a multi K-edge X-ray spectroscopic study

Di-iron dithiolate hydrogenase model complexes are promising systems for electrocatalytic production of dihydrogen and have therefore been spectroscopically and theoretically investigated in this study. The direct effect of ligand substitution on the redox activity of the complex is examined. In order to understand and eventually optimize such systems, we characterised both metal and ligand in detail, using element specific X-ray absorption Fe- and S-K edge XAS. The (electronic) structure of three different [Fe2S2] hydrogenase systems in their non-reduced state was investigated. The effect of one- and two-electron reduction on the (electronic) structure was subsequently investigated. The S K-edge XAS spectra proved to be sensitive to delocalization of the electron density into the aromatic ring. The earlier postulated charge and spin localization in these complexes could now be measured directly using XANES. Moreover, the electron density (from S K-edge XANES) could be directly correlated to the Fe–CO bond length (from Fe K-edge EXAFS), which are in turn both related to the reported catalytic activity of these complexes. The delocalization of the electron density into the conjugated π-system of the aromatic moieties lowers the basicity of the diiron core and since protonation occurs at the diiron (as a rate determining step), lowering the basicity decreases the extent of protonation and consequently the catalytic activity

Presence of Borrelia burgdorferi sensu lato antibodies in the serum of patients with abdominal aortic aneurysms

Infectious agents are likely to play a role in the pathogenesis of chronic inflammatory diseases, including abdominal aortic aneurysms (AAAs). The goal of this study was to determine if Borrelia burgdorferi sensu lato (sl), a microorganism responsible for Lyme disease, is involved in the etiology of AAAs. The presence of serum antibodies against B. burgdorferi sl was measured with enzyme-linked immunosorbent assay (ELISA) and confirmed by Western blotting in 96 AAA and 108 peripheral artery disease (PAD) patients. Polymerase chain reaction (PCR) was used for the detection of Borrelia-specific DNA in the aneurysm wall. Among AAA patients 34% and among PAD patients 16% were seropositive for B. burgdorferi sl antibodies (Fisher’s exact test, p = 0.003; odds ratio [OR] 2.79; 95% confidence interval [CI] 1.37–5.85). In the German general population, 3–17% are seropositive for Borrelia antibodies. No Borrelia DNA was detected in the aneurysm wall. Our findings suggest a relationship between AAAs and B. burgdorferi sl. We hypothesize that the underlying mechanism for B. burgdorferi sl in AAA formation is similar to that by the spirochete Treponema pallidum; alternatively, AAAs could develop due to induced autoimmunity via molecular mimicry due to similarities between some of the B. burgdorferi sl proteins and aortic proteins

Simulations of Ground Motion in the Los Angeles Basin Based upon the Spectral-Element Method

We use the spectral-element method to simulate ground motion generated by two recent and well-recorded small earthquakes in the Los Angeles basin. Simulations are performed using a new sedimentary basin model that is constrained by hundreds of petroleum-industry well logs and more than 20,000 km of seismic reflection profiles. The numerical simulations account for 3D variations of seismic-wave speeds and density, topography and bathymetry, and attenuation. Simulations for the 9 September 2001 M_w 4.2 Hollywood earthquake and the 3 September 2002 M_w 4.2 Yorba Linda earthquake demonstrate that the combination of a detailed sedimentary basin model and an accurate numerical technique facilitates the simulation of ground motion at periods of 2 sec and longer inside the basin model and 6 sec and longer in the regional model. Peak ground displacement, velocity, and acceleration maps illustrate that significant amplification occurs in the basin

Theory of Ferromagnetism in Doped Excitonic Condensates

Nesting in a semimetal can lead to an excitonic insulator state with spontaneous coherence between conduction and valence bands and a gap for charged excitations. In this paper we present a theory of the ferromagnetic state that occurs when the density of electrons in the conduction band and holes in the valence band differ. We find an unexpectedly rich doping-field phase diagram and an unusual collective excitation spectrum that includes two gapless collective modes. We predict regions of doping and external field in which phase-separated condensates of electrons and holes with parallel spins and opposing spins coexist.Comment: 5 pages, 3 postscript file