We present results from molecular dynamics simulations and contact angle measurements on graphite showing that this surface is indeed intrinsically mildly hydrophilic contrary to the common belief. ...Hydrocarbon contamination, known to be the source for the usually observed hydrophobic property of graphite, also affects protein adsorption processes as shown in this study. In the computational part of this work ethane was used as a model hydrocarbon which acts on the surface by reducing the water–surface and protein–surface interactions. This contamination then results in higher water contact angles. The process of protein adsorption is studied for the example of insulin revealing a reduction in adsorption strength despite the surface being more hydrophobic when contaminated. Although the proteins did not denature on the contaminated surfaces, further processes, such as the displacement of hydrocarbons by the protein, may occur on a longer time scale. In conclusion, we argue that proteins adsorb faster on pure than on contaminated surfaces with respect to the molecular dynamics time scale of ns.
The functionalization of semiconducting single-walled carbon nanotubes (SWNTs) with sp3 defects that act as luminescent exciton traps is a powerful means to enhance their photoluminescence quantum ...yield (PLQY) and to add optical properties. However, the synthetic methods employed to introduce these defects are currently limited to aqueous dispersions of surfactant-coated SWNTs, often with short tube lengths, residual metallic nanotubes, and poor film-formation properties. In contrast to that, dispersions of polymer-wrapped SWNTs in organic solvents feature unrivaled purity, higher PLQY, and are easily processed into thin films for device applications. Here, we introduce a simple and scalable phase-transfer method to solubilize diazonium salts in organic nonhalogenated solvents for the controlled reaction with polymer-wrapped SWNTs to create luminescent aryl defects. Absolute PLQY measurements are applied to reliably quantify the defect-induced brightening. The optimization of defect density and trap depth results in PLQYs of up to 4% with 90% of photons emitted through the defect channel. We further reveal the strong impact of initial SWNT quality and length on the relative brightening by sp3 defects. The efficient and simple production of large quantities of defect-tailored polymer-sorted SWNTs enables aerosol-jet printing and spin-coating of thin films with bright and nearly reabsorption-free defect emission, which are desired for carbon nanotube-based near-infrared light-emitting devices.
1. Agri-environment schemes attempt to counteract the loss of biodiversity and associated ecosystem services such as pollination and natural pest control in agro-ecosystems. However, only a few ...studies have evaluated whether these attempts are successful. 2. We studied the effects of managing meadows according to the prescriptions of ecological compensation areas (ECA), the most widely adopted agri-environment scheme in Switzerland, on both pollinator species richness and abundance, and the reproductive success of plants in nearby intensively managed meadows (IM). 3. We established arrays of four pots, each containing individuals of three insect-pollinated, non-autogamous 'phytometer' species (Raphanus sativus, Hypochaeris radicata and Campanula glomerata), in ECA and adjacent IM at increasing distances from the ECA at 13 sites. 4. Species richness and abundance of hoverflies, solitary bees and large-sized pollinators (mainly social bees and butterflies) were significantly higher in ECA than in adjacent IM. Species richness and abundance of small-sized pollinators in IM declined significantly with increasing distance from ECA, whereas large-sized pollinators were not significantly affected by distance. Plant species richness and flower abundance were the major drivers of pollinator species richness and abundance; the area of an ECA had no significant influence. 5. Individual plants of R. sativus and C. glomerata produced more and heavier seeds in ECA than in IM. Furthermore, the number of seeds of these two phytometer species was positively correlated with species richness and abundance of bees. No such effects were observed for individual plants of H. radicata. The number of fruits and seeds per plant of R. sativus in IM decreased with increasing distance from ECA. 6. Synthesis and applications. We conclude that establishing ECA is an effective method of enhancing both pollinator species richness and abundance and pollination services to nearby intensely managed farmland. Our study emphasizes the importance of connectivity between ECA in maintaining diverse pollinator communities and thereby providing pollination services in agricultural landscapes.
In many fields of technological developments, understanding and controlling material fatigue is an important point of interest. This article is concerned with statistical modeling of the damage ...process of prestressed concrete under low cyclic load. A crack width process is observed which exhibits jumps with increasing frequency. Firstly, these jumps are modeled using a Poisson process where two intensity functions are presented and compared. Secondly, based on the modeled jump process, a stochastic process for the crack width is considered through a stochastic differential equation (SDE). It turns out that this SDE has an explicit solution. For both modeling steps, a Bayesian estimation and prediction procedure is presented.
•A new statistical model for the damage process of prestressed concrete under low cyclic load with ability for prediction.•Bayesian inference for a jump diffusion process based on a nonhomogeneous Poisson process.•Two-stage modeling because of observed jumps: 1) the counting process is modeled,2) the jump diffusion process itself.•For prediction of crack width process, the uncertainties of parameters and the latent Poisson process are included.
1. The consequences of species loss on ecosystem functioning within a single trophic level have been extensively studied. However, the loss of basal species is likely to have profound impacts on the ...abundance, richness and ecosystem functioning of species at higher trophic levels. 2. Here, we used experimentally established plant communities with a species richness gradient to study the effects of plant species loss on a multi-trophic insect community in the field. We measured densities and species richness of aphids and parasitic wasps (primary, secondary and facultative tertiary parasitoids of aphids) that naturally colonized the grassland plots. 3. Furthermore, we calculated two ecosystem functions: aphid load (the number of aphid individuals per host plant biomass used as a proxy for herbivory) and parasitism rate. We used structural equation models to explore pathways of direct and indirect effects of plant species richness on higher trophic levels. 4. We found that the densities and richness of species at all trophic levels were influenced by changes in plant species richness. The effects were rarely direct, but instead mediated by the abundance and species richness of aphid host plants and subsequent trophic levels. 5. The herbivore and primary parasitoid levels were most directly affected by changes in plant species richness, with highest insect densities and species richness occurring at intermediate plant species richness. The densities and species richness of secondary parasitoids declined linearly with plant species richness owing to sparser resources, resulting in shorter food chains in communities with the highest plant species richness. 6. Aphid load was highest at intermediate plant species richness and negatively affected by both host plant biomass and host plant species richness. Parasitism rate was mostly affected indirectly via aphid density and overall only weakly negatively related to plant species richness. 7. Our results demonstrate that plant species richness can have strong cascading effects up to high trophic levels. However, their direction may differ at the lower and higher ends of the plant species richness spectrum, cautioning against simplifying consequences of plant species loss for specialist food webs that may become limited by sparse resources at high plant richness.
Based on accelerated lifetime experiments, we consider the problem of constructing prediction intervals for the time point at which a given number of components of a load‐sharing system fails. Our ...research is motivated by lab experiments with prestressed concrete beams where the tension wires fail successively. Due to an audible noise when breaking, the time points of failure could be determined exactly by acoustic measurements. Under the assumption of equal load sharing between the tension wires, we present a model for the failure times based on a birth process. We provide a model check based on a Q‐Q plot including a simulated simultaneous confidence band and four simulation‐free prediction methods. Three of the prediction methods are given by confidence sets where two of them are based on classical tests and the third is based on a new outlier‐robust test using sign depth. The fourth method uses the implicit function theorem and the δ‐method to get prediction intervals without confidence sets for the unknown parameter. We compare these methods by a leave‐one‐out analysis of the data on prestressed concrete beams. Moreover, a simulation study is performed to discuss advantages and drawbacks of the individual methods.
Force spectroscopy and especially single cell force spectroscopy with bacterial probes provide a powerful tool for the investigation of bacterial adhesion to different surfaces. Thereby, a crucial ...step is the immobilization of the bacteria on the cantilever. Until today, there have been developed versatile methods to attach bacteria to a cantilever, but only few studies compare these methods in a quantitative way. In this work, different functionalizations of the cantilever as well as two picking‐up parameters for three gram‐positive bacteria are evaluated. While there is no functionalization which works best for all of the bacteria, polydopamine, the adhesive protein Cell‐TakTM and a gas phase silanization in combination with an activation of the bacteria are the most promising candidates. Further, some general trends how the two investigated picking‐up parameters influence the adhesive behavior of the bacteria on the cantilever, which also depends strongly on the shape of the bacteria are presented.
Bacterial adhesion is the first step in the formation of a biofilm and can be studied by single cell force spectroscopy. In this study the potential of different functionalizations to create single cell bacterial probes using gram‐positive bacteria and tipless silicon cantilevers are investigated. Even though covalent fixation generally seems to work best, there are big differences between the three tested bacterial strains.
In this paper, we present a new algorithm for the detection of distorted and overlapping circlelike objects in noisy grayscale images. Its main step is an edge detection using rotated difference ...kernel estimators. To the resulting estimated edge points, circles are fitted in an iterative manner using a circular clustering algorithm. A new measure of similarity can assess the performance of algorithms for the detection of circlelike objects, even if the number of detected circles does not coincide with the number of true circles.
We apply the algorithm to scanning electron microscope images of a high‐velocity oxygen fuel (HVOF) spray process, which is a popular coating technique. There, a metal powder is fed into a jet, gets accelerated and heated up by means of a mixture of oxygen and fuel, and finally deposits as coating upon a substrate. If the process is stopped before a continuous layer is formed, the molten metal powder solidifies in form of small, almost circular so‐called splats, which vary with regard to their shape, size, and structure and can overlap each other. As these properties are challenging for existing image processing algorithms, engineers analyze splat images manually up to now.
We further compare our new algorithm with a baseline approach that uses the Laplacian of Gaussian blob detection. It turns out that our algorithm performs better on a set of test images of round, spattered, and overlapping circles.
Obesity and its impact on COVID-19 de Leeuw, Angélica J. M.; Oude Luttikhuis, Maureen A. M.; Wellen, Annemarijn C. ...
Journal of molecular medicine,
07/2021, Letnik:
99, Številka:
7
Journal Article
Recenzirano
Odprti dostop
The severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) pandemic has proven a challenge to healthcare systems since its first appearance in late 2019. The global spread and devastating ...effects of coronavirus disease 2019 (COVID-19) on patients have resulted in countless studies on risk factors and disease progression. Overweight and obesity emerged as one of the major risk factors for developing severe COVID-19. Here we review the biology of coronavirus infections in relation to obesity. In particular, we review literature about the impact of adiposity-related systemic inflammation on the COVID-19 disease severity, involving cytokine, chemokine, leptin, and growth hormone signaling, and we discuss the involvement of hyperactivation of the renin-angiotensin-aldosterone system (RAAS). Due to the sheer number of publications on COVID-19, we cannot be completed, and therefore, we apologize for all the publications that we do not cite.
Scanning force microscopy (SFM) is one of the most widely used techniques in biomaterials research. In addition to imaging the materials of interest, SFM enables the mapping of mechanical properties ...and biological responses with sub-nanometer resolution and piconewton sensitivity. This review aims to give an overview of using the scanning force microscope (SFM) for investigations on dental materials. In particular, SFM-derived methods such as force-distance curves (scanning force spectroscopy), lateral force spectroscopy, and applications of the FluidFM
will be presented. In addition to the properties of dental materials, this paper reports the development of the pellicle by the interaction of biopolymers such as proteins and polysaccharides, as well as the interaction of bacteria with dental materials.
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