399 research outputs found
High mobility dry-transferred CVD bilayer graphene
We report on the fabrication and characterization of high-quality chemical
vapor-deposited (CVD) bilayer graphene (BLG). In particular, we demonstrate
that CVD-grown BLG can mechanically be detached from the copper foil by an
hexagonal boron nitride (hBN) crystal after oxidation of the copper-to-BLG
interface. Confocal Raman spectroscopy reveals an AB-stacking order of the BLG
crystals and a high structural quality. From transport measurements on fully
encapsulated hBN/BLG/hBN Hall bar devices we extract charge carrier mobilities
up to 180,000 cm/(Vs) at 2 K and up to 40,000 cm/(Vs) at 300 K,
outperforming state-of-the-art CVD bilayer graphene devices. Moreover, we show
an on-off ration of more than 10,000 and a band gap opening with values of up
to 15 meV for a displacement field of 0.2 V/nm in such CVD grown BLG.Comment: 5 pages, 4 figure
The Effect of Dexamethasone, Adrenergic and Cholinergic Receptor Agonists on Phospholipid Metabolism in Human Osteoarthritic Synoviocytes
Phospholipids (PLs) possess the unique ability to contribute to synovial joint lubrication. The aim of our study was to determine for the first time the effect of dexamethasone and some adrenergic and cholinergic agonists on the biosynthesis and release of PLs from human fibroblast-like synoviocytes (FLS). Osteoarthritic human knee FLS were treated with dexamethasone, terbutaline, epinephrine, carbachol, and pilocarpine, or the glucocorticoid receptor antagonist RU 486. Simultaneously PL biosynthesis was determined through the incorporation of stable isotope-labeled precursors into PLs. Radioactive isotope-labeled precursors were used to radiolabel PLs for the subsequent quantification of their release into nutrient media. Lipids were extracted and quantified using electrospray ionization tandem mass spectrometry or liquid scintillation counting. Dexamethasone significantly decreased the biosynthesis of phosphatidylcholine, phosphatidylethanolamine (PE), PE-based plasmalogen, and sphingomyelin. The addition of RU 486 abolished these effects. A release of PLs from FLS into nutrient media was not recognized by any of the tested agents. None of the adrenergic or cholinergic receptor agonists modulated the PL biosynthesis. We demonstrate for the first time an inhibitory effect of dexamethasone on the PL biosynthesis of FLS from human knees. Moreover, our study indicates that the PL metabolism of synovial joints and lungs are differently regulated
Cerebrospinal fluid outflow along lumbar nerves and possible relevance for pain research: case report and review
CSF outflow through the cribriform plate near the olfactory
nerves and the outflow along brain and spinal nerves
are together known as peripheral CSF outflow pathway
(PCOP). It is still not clear whether the PCOP has pathogenetic
relevance. Our previous clinical observations have indicated
that CSF may interact with nerves along the PCOP
and in this article we present our finding of CSF outflow
demonstrated by myelography in a single patient. We also
discuss unexplained experimental pain pathomechanisms
against the background of the PCOP hypothesis. We observed
that CSF flowed along lumbar nerves in distal direction
at a speed of about 10 cm per hour on its way through
the tissues, mainly muscles. Total CSF outflow volume at
the lumbar site was remarkable. CSF outflow at lumbar
nerves was also documented by neuroradiology. It is plausible
that CSF signaling serves for interaction with nerves
along the PCOP, which could explain previously unknown
pathomechanisms in pain generation. Experimental findings
of tactile pain hypersensitivity within lumbosacral
pain pathways could be explained by releasing of molecules,
microparticles, or exosomes into the CSF by mast
cells, which then move with CSF outflow along the PCOP
and interact with nerves, initiating even retrograde synaptic
stripping
Raman spectroscopy as probe of nanometer-scale strain variations in graphene
Confocal Raman spectroscopy is a versatile, non-invasive investigation tool
and a major workhorse for graphene characterization. Here we show that the
experimentally observed Raman 2D line width is a measure of nanometer-scale
strain variations in graphene. By investigating the relation between the G and
2D line at high magnetic fields we find that the 2D line width contains
valuable information on nanometer-scale flatness and lattice deformations of
graphene, making it a good quantity for classifying the structural quality of
graphene even at zero magnetic field.Comment: 7 pages, 4 figure
Dental and Maxillofacial Cone Beam CT-High Number of Incidental Findings and Their Impact on Follow-Up and Therapy Management.
Cone beam computed tomography (CBCT) is increasingly used for dental and maxillofacial imaging. The occurrence of incidental findings has been reported, but clinical implications of these findings remain unclear. The study's aim was to identify the frequency and clinical impact of incidental findings in CBCT. A total of 374 consecutive CBCT examinations of a 3 year period were retrospectively evaluated for the presence, kind, and clinical relevance of incidental findings. In a subgroup of 54 patients, therapeutic consequences of CBCT incidental findings were queried from the referring physicians. A total of 974 incidental findings were detected, involving 78.6% of all CBCT, hence 2.6 incidental findings per CBCT. Of these, 38.6% were classified to require treatment, with an additional 25.2% requiring follow-up. Incidental findings included dental pathologies in 55.3%, pathologies of the paranasal sinuses and airways in 29.2%, osseous pathologies in 14.9% of all CBCT, and findings in the soft tissue or TMJ in few cases. Clinically relevant dental incidental findings were detected significantly more frequently in CBCT for implant planning compared to other indications (60.7% vs. 43.2%, p < 0.01), and in CBCT with an FOV ≥ 100 mm compared to an FOV < 100 mm (54.7% vs. 40.0%, p < 0.01). Similar results were obtained for paranasal incidental findings. In a subgroup analysis, 29 of 54 patients showed incidental findings which were previously unknown, and the findings changed therapeutical management in 19 patients (35%). The results of our study highlighted the importance of a meticulous analysis of the entire FOV of CBCT for incidental findings, which showed clinical relevance in more than one in three patients. Due to a high number of clinically relevant incidental findings especially in CBCT for implant planning, an FOV of 100 × 100 mm covering both the mandible and the maxilla was concluded to be recommendable for this indication
Deep metagenome and metatranscriptome analyses of microbial communities affiliated with an industrial biogas fermenter, a cow rumen, and elephant feces reveal major differences in carbohydrate hydrolysis strategies
Additional file 4. Compressed rar file containing the bins generated from the biogas fermenter metagenome, part 4 of 4
Mode of action-based risk assessment of genotoxic carcinogens
The risk assessment of chemical carcinogens is one major task in toxicology. Even though exposure has been mitigated effectively during the last decades, low levels of carcinogenic substances in food and at the workplace are still present and often not completely avoidable. The distinction between genotoxic and non-genotoxic carcinogens has traditionally been regarded as particularly relevant for risk assessment, with the assumption of the existence of no-effect concentrations (threshold levels) in case of the latter group. In contrast, genotoxic carcinogens, their metabolic precursors and DNA reactive metabolites are considered to represent risk factors at all concentrations since even one or a few DNA lesions may in principle result in mutations and, thus, increase tumour risk. Within the current document, an updated risk evaluation for genotoxic carcinogens is proposed, based on mechanistic knowledge regarding the substance (group) under investigation, and taking into account recent improvements in analytical techniques used to quantify DNA lesions and mutations as well as “omics” approaches. Furthermore, wherever possible and appropriate, special attention is given to the integration of background levels of the same or comparable DNA lesions. Within part A, fundamental considerations highlight the terms hazard and risk with respect to DNA reactivity of genotoxic agents, as compared to non-genotoxic agents. Also, current methodologies used in genetic toxicology as well as in dosimetry of exposure are described. Special focus is given on the elucidation of modes of action (MOA) and on the relation between DNA damage and cancer risk. Part B addresses specific examples of genotoxic carcinogens, including those humans are exposed to exogenously and endogenously, such as formaldehyde, acetaldehyde and the corresponding alcohols as well as some alkylating agents, ethylene oxide, and acrylamide, but also examples resulting from exogenous sources like aflatoxin B, allylalkoxybenzenes, 2-amino-3,8-dimethylimidazo[4,5-f] quinoxaline (MeIQx), benzo[a]pyrene and pyrrolizidine alkaloids. Additionally, special attention is given to some carcinogenic metal compounds, which are considered indirect genotoxins, by accelerating mutagenicity via interactions with the cellular response to DNA damage even at low exposure conditions. Part C finally encompasses conclusions and perspectives, suggesting a refined strategy for the assessment of the carcinogenic risk associated with an exposure to genotoxic compounds and addressing research needs
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