57 research outputs found

    Application of high‐performance DIC for a comprehensive evaluation of biaxial fatigue crack growth experiments

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    Precise determination of the remaining service life of technical components requires sufficient knowledge of fatigue crack growth behaviour and the growth rate of defects. Cracks in real components often experience multiaxial far field stresses due to their complex geometry and composite loadings acting on it. Digital image correlation (DIC) is well established for crack length and displacement measurements, but it usually requires sample preparation with speckle paint and interferes with mechanical extensometers. To overcome these limitations, we use a novel 2D DIC system combining a graphics processing unit (GPU) with a CoaXPress 2.0 camera, acquiring up to 3 GB/s of image data. It enables real‐time evaluation of both integral strain like an extensometer and full‐field DIC on images selected automatically in real‐time. This combination enables the use of one single sensor for strain‐controlled testing and fatigue crack growth characterisation. The full‐field displacement is compared to a finite‐element model (FEM) simulating the actual crack contour measured by the DIC system. The results show that high‐performance DIC has the potential to simultaneously simplify crack‐growth experiments and provide comprehensive fracture mechanical information

    Epigenetic inactivation of ITIH5 promotes bladder cancer progression and predicts early relapse of pT1 high-grade urothelial tumours

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    Inter-α-trypsin inhibitor heavy chain 5 (ITIH5) has been associated with tumour suppression in various cancers. However, its putative role in bladder cancer is completely unknown. Therefore, we initiated a study analysing ITIH5 expression as well as its prognostic and functional impact on human urothelial cancers (UCs). Expression analysis showed a clear down-regulation of ITIH5 mRNA in 61% (n = 45) of UCs, especially in muscle-invasive tumours (P < 0.001). ITIH5 loss in UCs was further evident on protein level (65.5%, n = 55) as detected by immunohistochemistry. DNA methylation analysis demonstrated tumour-specific ITIH5 promoter methylation in 50% of papillary none-invasive pTa (n = 30) and 68% of invasive (n = 28) UCs. Aberrant ITIH5 promoter methylation in bladder tumours was tightly linked (P < 0.001) with loss of ITIH5 mRNA expression, which was furthermore functionally confirmed by demethylation analysis in cell lines. Pyrosequencing analysis revealed that ITIH5 promoter hypermethylation was closely associated with progressive bladder cancers. Subsequently, a large cohort (n = 120) of clinically challenging pT1 high-grade UC was analysed for ITIH5 expression. Of clinical significance, we found an association between loss of ITIH5 expression and unfavourable prognosis of UC patients without distant metastasis at first diagnosis (recurrence-free survival; hazard ratio: 4.35, P = 0.048). Functionally, ITIH5 re-expression in human RT112 bladder cancer cells led to both suppression of cell migration and inhibition of colony spreading. Hence, we provide evidence that down-regulation of ITIH5 by aberrant DNA hypermethylation may provoke invasive phenotypes in human bladder cancer. Moreover, ITIH5 protein might become a prognostic biomarker for relapse risk stratification in high-grade UC patients

    Alkali metal derivatives of an ortho-phenylene diamine

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    Treatment of the ortho-phenylene diamine C6H4-1,2-{N(H)Tripp}2 (1, PDAH2, Tripp = 2,4,6-triisopropylphenyl) with two equivalents of MR (M = Li, R = Bun; M = Na or K, R = CH2C6H5) afforded the dimetallated alkali metal ortho-phenylene diamide dianion complexes [(PDALi2)(THF)3] (2), [{(PDANa2)(THF)2}2] (3), and [{(PDAK2)(THF)3}2] (4). In contrast, treatment of 2 with two equivalents of rubidium or cesium 2-ethylhexoxide, or treatment of 1 with two equivalents of MR (M = Rb or Cs, R = CH2C6H5) did not afford the anticipated dialkali metal ortho-phenylene diamide dianion derivatives and instead formally afforded the monometallic ortho-diiminosemiquinonate radical anion species [PDAM] (M = Rb, 5; M = Cs, 6). The structure of 2 is monomeric with one lithium coordinated to the two nitrogen centres and the other lithium η4-coordinated to the diazabutadiene portion of the PDA scaffold. Similar structural cores are observed for 3 and 4, except that the larger sodium and potassium ions give dimeric structures linked by multi-hapto interactions from the PDA backbone phenyl ring to an alkali metal centre. Complex 5 was not characterised in the solid state, but the structure of 6 reveals coordination of cesium ions to both PDA amide centres and multi-hapto interactions to a PDA backbone phenyl ring in the next unit to generate a one-dimensional polymer. Complexes 2–6 have been variously characterised by X-ray crystallography, multi-nuclear NMR, FTIR, and EPR spectroscopies, and CHN microanalyses

    Evidence-Based Guidelines for Empirical Therapy of Neutropenic Fever in Korea

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    Neutrophils play an important role in immunological function. Neutropenic patients are vulnerable to infection, and except fever is present, inflammatory reactions are scarce in many cases. Additionally, because infections can worsen rapidly, early evaluation and treatments are especially important in febrile neutropenic patients. In cases in which febrile neutropenia is anticipated due to anticancer chemotherapy, antibiotic prophylaxis can be used, based on the risk of infection. Antifungal prophylaxis may also be considered if long-term neutropenia or mucosal damage is expected. When fever is observed in patients suspected to have neutropenia, an adequate physical examination and blood and sputum cultures should be performed. Initial antibiotics should be chosen by considering the risk of complications following the infection; if the risk is low, oral antibiotics can be used. For initial intravenous antibiotics, monotherapy with a broad-spectrum antibiotic or combination therapy with two antibiotics is recommended. At 3-5 days after beginning the initial antibiotic therapy, the condition of the patient is assessed again to determine whether the fever has subsided or symptoms have worsened. If the patient's condition has improved, intravenous antibiotics can be replaced with oral antibiotics; if the condition has deteriorated, a change of antibiotics or addition of antifungal agents should be considered. If the causative microorganism is identified, initial antimicrobial or antifungal agents should be changed accordingly. When the cause is not detected, the initial agents should continue to be used until the neutrophil count recovers

    Resonante PEPICO-Spektroskopie an Hg als Basis fĂŒr ein Bell-Experiment

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    Seit Einstein, Podolsky und Rosen 1935 mit dem spĂ€ter nach ihnen benannten EPR-Paradoxon die Frage nach der Struktur von LokalitĂ€t und KausalitĂ€t in der Quantenmechanik aufgeworfen haben, wurde diese in der Physik heftig diskutiert. Dank der Arbeiten von Bell ist es heute - abseits von naturphilosophischen Diskussionen - möglich, sich dieser Fragestellung auf experimentellem Wege zu nĂ€hern. Alle bis dato unternommenen Versuche krankten jedoch an den Imperfektionen der praktischen DurchfĂŒhrung, die als Schlupflöcher ihren festen Platz in der Debatte gefunden haben. Ein neuartiges Bell-Experiment auf der Basis von spin-verschrĂ€nkten 199Hg-Atompaaren hat das Potenzial diese zu schließen und eine endgĂŒltige Antwort auf EPR zu geben. Die vorliegende Dissertation beschĂ€ftigt sich mit der Modellierung, Konstruktion und Charakterisierung eines empfindlichen Detektorsystems fĂŒr Quecksilber und stellt damit einen wichtigen Baustein fĂŒr eben dieses Bell-Experiment dar. Das System basiert auf einem resonanten, zwei-stufigen Ionisationsprozess in einen autoionisierenden Zustand. Als Quelle fĂŒr die beiden benötigten WellenlĂ€ngen dient ein gepulster, regenerativer Ti:Saphir-VerstĂ€rker, der simultan 5.5 ns lange, gaußförmige Pulse mit Energien bis 2.4 mJ bei 761 nm und 3.8 mJ bei 789 nm erzeugt. Durch effiziente Single-Pass-Frequenzkonversion wurden so Energien von 580 ”J beziehungsweise 180 ”J bei den beiden ZielwellenlĂ€ngen 253.7 nm und 197.2 nm erreicht. Diese wurden in einer UHV-Testkammer zur Ionisation von Quecksilberatomen in der Gasphase verwendet. Als eigentlicher Detektor kommt ein System aus elektrostatischen Optiken in Kombination mit Kanal-Elektronen-Vervielfachern zum Einsatz. Durch Anpassung der Detektorgeometrie und der kinetischen Energie der Teilchen beim Auftreffen auf die Detektoren konnte eine kombinierte Effizienz von 0.897 erreicht werden, was die Voraussetzungen fĂŒr ein erfolgreiches Gelingen des Bell-Experimentes erfĂŒllt

    King tuna: Indian Ocean trade, offshore fishing, and coral reef resilience in the Maldives archipelago

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    The traditional offshore pole-and-line tuna fishery of the Maldives has historically promoted low levels of reef fishing in this archipelago. While the tuna fishery is old and extensive-some evidence suggests it has been in place for over a thousand years-the reasons for its development have not been closely examined. Why did an offshore fishery develop in such small and isolated islands with abundant and easily accessible nearshore reefs? Why is tuna considered the "king of fish" in the Maldives, in contrast to many other islands across the globe where reef fish are prized for a wide variety of cultural and social reasons, often deeply rooted in community histories? In this article, we use a historical approach to uncover some of the drivers of this fishery, and the long-term consequences it has had for the resilience of this island chain. We trace the written accounts of travellers, voyagers, and traders, in addition to more recent research to gain an understanding of how early Indian Ocean trade networks may have shaped the development of this fishery over time. We propose that the early growth of the tuna fishery was likely tied to the trade in money cowries (Monetaria moneta), of which the Maldives was a major global supplier. A regional demand and market for dried tuna from the fourteenth century onwards contributed to the income of Maldivians and promoted and supported reef health by encouraging relatively low levels of reef fishing. However, the emergence and substantial growth of the Maldivian tourist industry in the past few decades are resulting in a shift in local consumption preferences and increased exploitation of reef fisheries. Exploring this history is important, not only to help contextualize the modern governance of the offshore tuna fishery, but also for a more nuanced understanding of the social, cultural, and ecological dynamics that have shaped Maldivian coral reefs in the past with implications for those that will do so in the future

    Digital Holographic Microscopy for 200 € Using Open-Source Hard- and Software

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    3D-printed mounts and off-the-shelf components result in a digital holographic microscope for 200 € - including camera and computer. Short source code and a simple design put noninvasive quantitative bio-imaging within reach of secondary schools

    Extending the depth of field beyond geometrical imaging limitations using phase noise as a focus measure in multiwavelength digital holography

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    Digital holography is a well-established technology for optical quality control in industrial applications. Two common challenges in digital holographic measurement tasks are the ambiguity at phase steps and the limited depth of focus. With multiwavelength holography, multiple artificial wavelengths are used to extend the sensor’s measurement range up to several millimeters, allowing measurements on rough surfaces. To further extend the unambiguous range, additional highly stabilized and increasingly expensive laser sources can be used. Besides that, unwrapping algorithms can be used to overcome phase ambiguities—but these require continuous objects. With the unique feature of numerical refocusing, digital holography allows the numerical generation of an all-in-focus unambiguous image. We present a shape-from-focus algorithm that allows the extension of the depth of field beyond geometrical imaging limitations and yields unambiguous height information, even across discontinuities. Phase noise is used as a focus criterion and to generate a focus index map. The algorithm’s performance is demonstrated at a gear flank with steep slopes and a step sample with discontinuities far beyond the system’s geometrical limit. The benefit of this method on axially extended objects is discussed

    Multiwavelength digital holography: Height measurements on linearly moving and rotating objects

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    Multiwavelength digital holography enables precise and fast 3D height measurements of rough surfaces. To inspect objects during motion would enlarge the range of applications enormously. In this work the limits of this technique with respect to velocity and inclination angles are studied for linearly moving as well as for rotating objects. We demonstrate measurements on surfaces with inclination angles of up to 40° , moving linearly with a velocity of 2 mm/s, providing 2 Όm accuracy, and on a rotating cylinder with circumferential speed of 10 mm/s, we achieve 1.1 Όm precision. All measurements are conducted with less than 1 mW of continuous-wave laser light, so the object moves several micrometers during exposure time
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