728 research outputs found

    How residual stresses affect the fracture properties of layered thin films

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    The continued miniaturization effort has revealed exciting new material behavior at small length scales, where pronounced size effects come into play and material properties are subject to change. This has led to the development of miniaturized testing techniques to determine local plastic properties. So far, however, only few efforts regarding the determination of residual stresses and fracture properties in miniaturized systems were made. In this presentation, we will focus on recent developments regarding the measurement of residual stresses and miniaturized fracture properties using FIB based sample preparation and in situ SEM experiments. The depth resolved residual film stresses are determined by an improved stepwise beam layer removal method [1]. From the same film systems, beams are FIB fabricated for miniaturized fracture testing in the SEM [2]. We will discuss the general possibilities, challenges, and benefits of these approaches by examining the internal stresses and fracture properties of single layer and multilayer thin films in the immiscible system Cu-W. Particular emphasis is placed on the effect of residual stresses on the fracture properties. Moreover, possible limitations of commonly used data analysis approaches are addressed, and related improvements using finite element modelling to determine crack-driving forces in the presence of interfaces and residual stresses are presented [3]. Notably, the required material input data in terms of flow behavior for this modeling approach was determined using spherical nanoindentation experiments on single and multilayer films. Finally, the possibility of further miniaturization of such experiments by using in situ TEM is demonstrated [4]

    Solar cell emitter design with PV-tailored implantation

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    A potentially cost-effective ion implanter for solar cells has become commercially available very recently. As the emitter dopant profiles differ from the standard diffusions, a combination of process simulation and device simulation is used to predict possible applications as front emitter. The simulations show that ion energies of 10 to 30 keV and doses in the range of 5Ă—1014 to 7Ă—1015 cm-2 are sufficient for reducing the phosphorus peak density and, hence, obtaining cell efficiency levels above 20%, if appropriate surface passivation and wafer materials are used. The simulations strongly indicate, however, that cell efficiency improves only marginally if the cell has a fully metallized rear Al-BSF and a boron-doped Cz base in the degraded state. Simulated cells with a local rear Al-BSF show an efficiency improvement of more than 0.3% absolute in the degraded state

    Inbreeding, Microsatellite Heterozygosity, and Morphological Traits in Lipizzan Horses

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    While the negative effects of inbreeding and reduced heterozygosity on fecundity and survival are well established, only a few investigations have been carried out concerning their influence on morphological traits. This topic is of particular interest for a small and closed population such as the Lipizzan horse. Thus, 27 morphological traits were measured in 360 Lipizzan mares and were regressed on the individual inbreeding coefficients, as well as on the individual heterozygosity and mean squared distances (mean d2) between microsatellite alleles within an individual. Both individual heterozygosity and mean d2 were based on 17 microsatellite loci dispersed over 14 chromosomes. The results obtained by multivariate analysis reveal significant effects of stud (P <.0001), age at measurement (P <.0001), and mean d2 (P =.0143). In univariate analyses, significant associations were obtained between length of pastern-hindlimbs and inbreeding coefficient (P <.01), length of cannons-hindlimb and mean d2 (P <.01), and length of neck and mean d2 (P <.001). After adjustment of single-test P values for multiple tests (Hochberg's step-up Bonferroni method), only the association of the length of neck and mean d2 remained significant (P =.0213). Thus, no overall large effects of inbreeding, microsatellite heterozygosity, and mean d2 on morphological traits were observed in the Lipizzan hors

    Inbreeding, Microsatellite Heterozygosity, and Morphological Traits in Lipizzan Horses

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    While the negative effects of inbreeding and reduced heterozygosity on fecundity and survival are well established, only a few investigations have been carried out concerning their influence on morphological traits. This topic is of particular interest for a small and closed population such as the Lipizzan horse. Thus, 27 morphological traits were measured in 360 Lipizzan mares and were regressed on the individual inbreeding coefficients, as well as on the individual heterozygosity and mean squared distances (mean d2) between microsatellite alleles within an individual. Both individual heterozygosity and mean d2 were based on 17 microsatellite loci dispersed over 14 chromosomes. The results obtained by multivariate analysis reveal significant effects of stud (P <.0001), age at measurement (P <.0001), and mean d2 (P =.0143). In univariate analyses, significant associations were obtained between length of pastern-hindlimbs and inbreeding coefficient (P <.01), length of cannons-hindlimb and mean d2 (P <.01), and length of neck and mean d2 (P <.001). After adjustment of single-test P values for multiple tests (Hochberg's step-up Bonferroni method), only the association of the length of neck and mean d2 remained significant (P =.0213). Thus, no overall large effects of inbreeding, microsatellite heterozygosity, and mean d2 on morphological traits were observed in the Lipizzan horse

    LETTER Communicated by Benjamin Schrauwen Regularized Variational Bayesian Learning of Echo State Networks with Delay&amp;Sum Readout

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    In this work, a variational Bayesian framework for efficient training of echo state networks (ESNs) with automatic regularization and delay&amp;sum (D&amp;S) readout adaptation is proposed. The algorithm uses a classical batch learning of ESNs. By treating the network echo states as fixed basis functions parameterized with delay parameters, we propose a variational Bayesian ESN training scheme. The variational approach allows for a seamless combination of sparse Bayesian learning ideas and a variational Bayesian space-alternating generalized expectationmaximization (VB-SAGE) algorithm for estimating parameters of superimposed signals. While the former method realizes automatic regularization of ESNs, which also determines which echo states and input signals are relevant for &quot;explaining&quot; the desired signal, the latter method provides a basis for joint estimation of D&amp;S readout parameters. The proposed training algorithm can naturally be extended to ESNs with fixed filter neurons. It also generalizes the recently proposed expectationmaximization-based D&amp;S readout adaptation method. The proposed algorithm was tested on synthetic data prediction tasks as well as on dynamic handwritten character recognition. Neural Computation 24, 967-995 (2012

    Unsaturated fatty acids are inhibitors of bacterial conjugation

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    This report describes a high-throughput assay to identify substances that reduce the frequency of conjugation in Gram-negative bacteria. Bacterial conjugation is largely responsible for the spread of multiple antibiotic resistances in human pathogens. Conjugation inhibitors may provide a means to control the spread of antibiotic resistance. An automated conjugation assay was developed that used plasmid R388 and a laboratory strain of Escherichia coli as a model system, and bioluminescence as a reporter for conjugation activity. Frequencies of conjugation could be measured continuously in real time by the amount of light produced, and thus the effects of inhibitory compounds could be determined quantitatively. A control assay, run in parallel, allowed elimination of compounds affecting cell growth, plasmid stability or gene expression. The automated conjugation assay was used to screen a database of more than 12 000 microbial extracts known to contain a wide variety of bioactive compounds (the NatChem library). The initial hit rate was 1·4 %. From these, 48 extracts containing active compounds and representing a variety of organisms and extraction conditions were subjected to fractionation (24 fractions per extract). The 52 most active fractions were subjected to a secondary analysis to determine the range of plasmid inhibition. Plasmids R388, R1 and RP4 were used as representatives of a variety of plasmid transfer systems. Only one fraction (of complex composition) affected transfer of all three plasmids, while four other fractions were active against two of them. Two separate compounds were identified from these fractions: linoleic acid and dehydrocrepenynic acid. Downstream analysis showed that the chemical class of unsaturated fatty acids act as true inhibitors of conjugation

    Analysis of Pain and Analgesia Protocols in Acute Cerulein-Induced Pancreatitis in Male C57BL/6 Mice

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    Pancreatitis is known to be painful in humans and companion animals. However, the extent of pain in experimental mouse models of acute pancreatitis is unknown. Consequently, the severity classification of acute pancreatitis in mice is controversially discussed and standardized pain management is missing. In this study, we investigated acute Cerulein-induced pancreatitis with pain-specific and well-being orientated parameters to detect its impact on mice. Male C57BL/6J male mice were injected with Cerulein; animals that received saline injections served as control group. The animals were observed for weight change and water intake. To assess pain, behaviors like stretch-and-press and reduced rearing, the Mouse Grimace Scale, and von Frey hypersensitivity were assessed. Fecal corticosterone metabolites and burrowing behavior were assessed to detect changes in the animal’s well-being. Pancreatitis severity was evaluated with amylase and lipase in the blood and pancreas histology. To investigate whether different analgesics can alleviate signs of pain, and if they influence pancreas inflammation, animals received Buprenorphine, Paracetamol in combination with Tramadol, or Metamizole in the drinking water. The calculated intake of these analgesics via drinking reached values stated to be efficient for pain alleviation. While pancreatitis did not seem to be painful, we detected acute pain from Cerulein injections that could not be alleviated by analgesics. The number of inflammatory cells in the pancreas did not differ with the analgesic administered. In conclusion: (1) Cerulein injections appear to be acutely painful but pain could not be alleviated by the tested analgesics, (2) acute pancreatitis induced by our protocol did not induce obvious signs of pain, (3) analgesic substances had no detectable influence on inflammation. Nevertheless, protocols inducing more severe or even chronic pancreatitis might evoke more pain and analgesic treatment might become imperative. Considering our results, we recommend the use of Buprenorphine via drinking water in these protocols. Further studies to search for efficient analgesics that can alleviate the acute pain induced by Cerulein injections are needed

    eHealth Platforms to Promote Autonomous Life and Active Aging: A Scoping Review

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    New technologies, namely eHealth platforms, are being used more than ever before. These platforms enable older people to have a more independent lifestyle, enhance their participation, and improve their well-being. Information and communication technologies are expected to be linked to the triad of aging, social inclusion, and active participation, which is in line with the implementation of Smart Healthy and Age-Friendly Environments. This scoping review aimed to map eHealth platforms designed to promote autonomous life and active aging. The Joanna Briggs Institute methodology and the PRISMA-ScR checklist were used. A search was conducted on MEDLINE (via PubMed), CINAHL Complete (via EBSCOhost), Scopus, Cochrane Database of Systematic Reviews (via EBSCOhost), SciELO, DART-Europe, CAPES, and MedNar databases. Fourteen studies were included. This scoping review synthesized information on eHealth platforms designed to promote active living, their domains of intervention, and the outcomes assessed in those studies that have implemented and evaluated these eHealth platforms

    High-Level Expression of Various Apolipoprotein (a) Isoforms by "Transferrinfection". The Role of Kringle IV Sequences in the Extracellular Association with Low-Density Lipoprotein

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    Characterization of the assembly of lipoprotein(a) [Lp(a)] is of fundamental importance to understanding the biosynthesis and metabolism of this atherogenic lipoprotein. Since no established cell lines exist that express Lp(a) or apolipoprotein(a) [apo(a)], a "transferrinfection" system for apo(a) was developed utilizing adenovirus receptor- and transferrin receptor-mediated DNA uptake into cells. Using this method, different apo(a) cDNA constructions of variable length, due to the presence of 3, 5, 7, 9, 15, or 18 internal kringle IV sequences, were expressed in cos-7 cells or CHO cells. All constructions contained kringle IV-36, which includes the only unpaired cysteine residue (Cys-4057) in apo(a). r-Apo(a) was synthesized as a precursor and secreted as mature apolipoprotein into the medium. When medium containing r-apo(a) with 9, 15, or 18 kringle IV repeats was mixed with normal human plasma LDL, stable complexes formed that had a bouyant density typical of Lp(a). Association was substantially decreased if Cys-4057 on r-apo(a) was replaced by Arg by site-directed mutagenesis or if Cys-4057 was chemically modified. Lack of association was also observed with r-apo(a) containing only 3, 5, or 7 kringle IV repeats without "unique kringle IV sequences", although Cys-4057 was present in all of these constructions. Synthesis and secretion of r-apo(a) was not dependent on its sialic acid content. r-Apo(a) was expressed even more efficiently in sialylation-defective CHO cells than in wild-type CHO cells. In transfected CHO cells defective in the addition of N-acetylglucosamine, apo(a) secretion was found to be decreased by 50%. Extracellular association with LDL was not affected by the carbohydrate moiety of r-apo(a), indicating a protein-protein interaction between r-apo(a) and apoB. These results show that, besides kringle IV-36, other kringle IV sequences are necessary for the extracellular association of r-apo(a) with LDL. Changes in the carbohydrate moiety of apo(a), however, do not affect complex formation
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