254 research outputs found
Check-list of European Orthoptera
List of all 974 recognized species of Ensifera (Tettigonioidea: 458, Rhaphidophoroidea: 44, Grylloidea: 91) and Caelifera (Tetrigoidea: 12, Tridactyloidea: 6, Acridoidea: 363) in Europe including information about their distribution.Aufstellung aller 974 derzeitig anerkannten Arten der Ensifera (Tettigonioidea: 458, Rhaphidophoroidea: 44, Grylloidea: 91) and Caelifera (Tetrigoidea: 12, Tridactyloidea: 6, Acridoidea: 363) in Europa mit Angabe der Verbreitungsgebiete
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Sorptive physiologically based extraction of contaminated solid matrices: incorporating silicone rod as absorption sink for hydrophobic organic contaminants
The oral bioaccessibility of soil contaminants is increasingly assessed with Physiologically Based Extraction Tests (PBETs) to fine tune human health risk assessment of contaminated land. In these tests the contaminant fraction that is desorbed into simulated digestive fluids is measured and classified as bioaccessible. However, this approach can lead to underestimations if the capacity of the fluids is insufficient to provide infinite bath conditions. To circumvent this artefact, we incorporated a silicone rod as an absorption sink into the PBET to continuously absorb mobilized contaminants and maintain the desorption gradient. Polycyclic aromatic hydrocarbons served as model contaminants and the colon extended PBET (CEPBET) as the extraction model. The inclusion of the silicone rod sink (1) increased the extraction capacity of the test by orders of magnitude, (2) ensured (near) infinite bath conditions and (3) allowed for simple back-extraction of PAHs for their quantification by GC-MS. The silicone rod provided fast enrichment when applied to the stomach and small intestine compartment, but was somewhat slower in the carbohydrate colon compartment. Finally, the sorptive-CEPBET was applied to wood soot and a kindergarten soil. The present article provides the basis for how an absorption sink can be integrated into PBET models
Nanomedicine for the reduction of the thrombogenicity of stent coatings
The treatment of patients with drug-eluting stents (DES) continues to evolve with the current emergence of DES technology that offers a combination of pharmacological and mechanical approaches to prevent arterial restenosis. However, despite the promising short-term and mid-term outcomes of DES, there are valid concerns about adverse clinical effects of late stent thrombosis. In this study, we present an example of how nanomedicine can offer solutions for improving stent coating manufacturing, by producing nanomaterials with tailored and controllable properties. The study is based on the exploitation of human platelets response towards carbon-based nanocoatings via atomic force microscope (AFM). AFM can facilitate the comprehensive analysis of platelets behavior onto stent nanocoatings and enable the study of thrombogenicity. Platelet-rich plasma from healthy donors was used for the real-time study of biointerfacial interactions. The carbon nanomaterials were developed by rf magnetron sputtering technique under controllable deposition conditions to provide favorable surface nanotopography. It was shown that by altering the surface topography of nanocoatings, the activation of platelets can be affected, while the carbon nanocoatings having higher surface roughness were found to be less thrombogenic in terms of platelets adhesion. This is an actual solution for improving the stent coating fabrication
Electrochemical peroxidation of contaminated water and assessment of the toxicity using existing and novel bioassays
The treatment of wastewater and monitoring of its toxicity is essential before discharging it to the environment. This study focuses on assessing the toxicity of wastewater following treatment using the electrochemical peroxidation process (ECP). Three categories of low-cost toxicity assays were used based on plant cells, microorganisms and invertebrates, all of which do not require ethical approval or a special licence. In addition, a novel cost-effective device was developed for assessing wastewater toxicity at low concentrations. In Chapter 2, the problem of high turbidity of the ECP-treated samples is addressed, by accelerating particulate settling of the existent compounds. This was achieved by storing the ECP treated samples at low temperatures. This is an essential step for enhancing the clarity of the processed samples in order to improve the performance of the toxicity assays.EThOS - Electronic Theses Online ServiceGBUnited Kingdo
How to Determine the Environmental Exposure of PAHs Originating from Biochar
Biochars are obtained by pyrolyzing
biomass materials and are increasingly
used within the agricultural sector. Owing to the production process,
biochars can contain polycyclic aromatic hydrocarbons (PAHs) in the
high mg/kg range, which makes the determination of the environmental
exposure of PAHs originating from biochars relevant. However, PAH
sorption to biochar is characterized by very high (10<sup>4</sup>–10<sup>6</sup> L/kg) or extreme distribution coefficients (<i>K</i><sub>D</sub>) (>10<sup>6</sup> L/kg), which makes the determination
of exposure scientifically and technically challenging. Cyclodextrin
extractions, sorptive bioaccessibility extractions, Tenax extractions,
contaminant traps, and equilibrium sampling were assessed and selected
methods used for the determination of bioavailability parameters for
PAHs in two model biochars. Results showed that: (1) the <i>K</i><sub>D</sub> values of typically 10<sup>6</sup>–10<sup>9</sup> L/kg made the biochars often act as sinks, rather than sources,
of PAHs. (2) Equilibrium sampling yielded freely dissolved concentrations
(pg–ng/L range) that were below or near environmental background
levels. (3) None of the methods were found to be suitable for the
direct measurement of the readily desorbing fractions of PAHs (i.e.,
bioacessibility) in the two biochars. (4) The contaminant-trap method
yielded desorption-resistant PAH fractions of typically 90–100%,
implying bioaccessibility in the high μg/kg to low mg/kg range
Human keratinocytes have two interconvertible modes of proliferation.
Single stem cells, including those in human epidermis, have a remarkable ability to reconstitute tissues in vitro, but the cellular mechanisms that enable this are ill-defined. Here we used live imaging to track the outcome of thousands of divisions in clonal cultures of primary human epidermal keratinocytes. Two modes of proliferation were seen. In 'balanced' mode, similar proportions of proliferating and differentiating cells were generated, achieving the 'population asymmetry' that sustains epidermal homeostasis in vivo. In 'expanding' mode, an excess of cycling cells was produced, generating large expanding colonies. Cells in expanding mode switched their behaviour to balanced mode once local confluence was attained. However, when a confluent area was wounded in a scratch assay, cells near the scratch switched back to expanding mode until the defect was closed. We conclude that the ability of a single epidermal stem cell to reconstitute an epithelium is explained by two interconvertible modes of proliferation regulated by confluence.The initial association of holoclone and paraclone type behaviour in clonal cultures of NFSK with stem and balanced progenitor dynamics was due to BDS working in collaboration with PHJ, VN-N, David Doupé and Allon Klein, based on the quantitative analysis of published and unpublished colony size distributions6 . We thank Gözde Akdeniz & David Doupé for experimental work that led up to the project that was analysed by Allon Klein and Genneth Zhang, Patrick Lombard at the Wellcome TrustMedical Research Council Cambridge Stem Cell Institute for Bioinformatics analysis and Esther Choolun for technical assistance. We acknowledge the support of the Wellcome Trust, Cambridge Cancer Centre, Medical Research Council, the NC3Rs (National Centre for the Replacement, Refinement and Reduction of Animals in Research) and Cancer Research UK (Programme grant C609/A17257).This is the author accepted manuscript. The final version is available from NPG via http://dx.doi.org/10.1038/ncb328
1,4-Bis[(2,2′:6′,2′′-terpyridin-4′-yl)Âoxy]butane
The title compound, C34H28N6O2, has an inversion centre located at the mid-point of the central C—C bond of the diether bridging unit. The central pyridine rings of the terpyridyl units and the diether chain are co-planar: the maximum deviation from the 18-atom mean plane defined by the bridging unit and the central pyridyl ring is for the pyridyl N atom which sits 0.055 (1) Å above the plane. The dihedral angles between the terminal pyridine rings with this plane are 10.3 (1) and 37.6 (1)°, repectively. In the crystal, weak C—H⋯N interÂactions link the molÂecules into infinite chains parallel to the a axis
Multilayered Inclusions in Locally Resonant Metamaterials: Two-Dimensional Versus Three-Dimensional Modeling
Locally resonant metamaterials (LRMs) controlling low-frequency waves due to resonant scattering are usually characterized by narrow band gaps (BGs) and a poor wave filtering performance. To remedy this shortcoming, multiresonant metamaterial structures with closely located BGs have been proposed and widely studied. However, the analysis is generally limited to two-dimensional (2D) structures neglecting the finite height of any real resonator. The aim of this paper is the comparison of the wave dispersion for two-and threedimensional (3D) metamaterial models and evaluation of the applicability ranges of 2D results. Numerical study reveals that dual-resonant structures with cylindrical inclusions possess only a single (compared to two in the 2D case) BG for certain height-to-width ratios. In contrast, the wave dispersion in metamaterials with multiple spherical resonators can be accurately evaluated using a 2D approximation, enabling a significant simplification of resource-consuming 3D models
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