2,238 research outputs found

    SHRIMP zircon geochronology of the Emeishan Large Igneous Province (SW China): implications for double mass extinctions in Late Permian

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    Abstract in http://www.lpi.usra.edu/meetings/gold2001/pdf/3519.pd

    Preparation and analysis of a new bioorganic metallic material

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    Biofouling on metal surfaces is one of the main reasons for increased ship drag. Many methods have already been used to reduce or remove it with moderate success. In this study, a synthetic peptide has been utilized to react with 304 stainless steel aiming to generate a bioorganic stainless steel using a facile technique. After the reaction, white matter was found on the surface of the treated stainless steel via SEM, whilst the nontreated stainless steel had none. Elemental analysis confirmed that excessive N existed on the surface of the treated samples using an integrated SEM-EDS instrument, implying the presence of peptides binding on the surface of the bioorganic stainless steel. The FTIR spectra showed amide A and II peaks on the surface of the bioorganic stainless steel suggesting that either the peptides grafted onto the steel surface or the polypeptide composition accumulated on the steel samples. XPS analysis of the treated steel demonstrated that there was nitrogen bonding on the surface and it was a chemical bond via a previously unreported chemical interaction. The treated steel has a markedly increased contact angle (water contact angle of 65.7 ± 4.7° for nontreated steel in comparison to treated, 96.4 ± 2.1°), which supported the observation of the wettability change of the surface, i.e. the decrease of the surface energy value after peptide treatment. The changes of the surface parameters (such as, Sa, Sq, Ssk and Sku) of the treated steel by surface analysis were observed

    On the Inability of Markov Models to Capture Criticality in Human Mobility

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    We examine the non-Markovian nature of human mobility by exposing the inability of Markov models to capture criticality in human mobility. In particular, the assumed Markovian nature of mobility was used to establish a theoretical upper bound on the predictability of human mobility (expressed as a minimum error probability limit), based on temporally correlated entropy. Since its inception, this bound has been widely used and empirically validated using Markov chains. We show that recurrent-neural architectures can achieve significantly higher predictability, surpassing this widely used upper bound. In order to explain this anomaly, we shed light on several underlying assumptions in previous research works that has resulted in this bias. By evaluating the mobility predictability on real-world datasets, we show that human mobility exhibits scale-invariant long-range correlations, bearing similarity to a power-law decay. This is in contrast to the initial assumption that human mobility follows an exponential decay. This assumption of exponential decay coupled with Lempel-Ziv compression in computing Fano's inequality has led to an inaccurate estimation of the predictability upper bound. We show that this approach inflates the entropy, consequently lowering the upper bound on human mobility predictability. We finally highlight that this approach tends to overlook long-range correlations in human mobility. This explains why recurrent-neural architectures that are designed to handle long-range structural correlations surpass the previously computed upper bound on mobility predictability

    Simultaneous quantitative assessment of circulating cell-free mitochondrial and nuclear DNA by multiplex real-time PCR

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    Quantification of circulating nucleic acids in plasma and serum could be used as a non-invasive diagnostic tool for monitoring a wide variety of diseases and conditions. We describe here a rapid, simple and accurate multiplex real-time PCR method for direct synchronized analysis of circulating cell-free (ccf) mitochondrial (mtDNA) and nuclear (nDNA) DNA in plasma and serum samples. The method is based on one-step multiplex real-time PCR using a FAM-labeled MGB probe and primers to amplify the mtDNA sequence of the ATP 8 gene, and a VIC-labeled MGB probe and primers to amplify the nDNA sequence of the glycerinaldehyde-3-phosphate-dehydrogenase (GAPDH) gene, in plasma and serum samples simultaneously. The efficiencies of the multiplex assays were measured in serial dilutions. Based on the simulation of the PCR reaction kinetics, the relative quantities of ccf mtDNA were calculated using a very simple equation. Using our optimised real-time PCR conditions, close to 100% efficiency was obtained from the two assays. The two assays performed in the dilution series showed very good and reproducible correlation to each other. This optimised multiplex real-time PCR protocol can be widely used for synchronized quantification of mtDNA and nDNA in different samples, with a very high rate of efficiency

    Multi-seeded melt growth (MSMG) of bulk Y-Ba-Cu-O using thin-film seeds

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    Y-Ba-Cu-O (YBCO) and Sm-Ba-Cu-O (SmBCO) thin films have been used for the first time as heterogeneous seeds to multi-seed successfully the melt growth of bulk YBCO in a multi-seeded melt growth (MSMG) process. The use of thin film seeds, which may be prepared with highly controlled orientation (i.e. with a well-defined a-b plane and precisely known a-direction), is based on their superheating properties and reduces significantly contamination of the bulk sample by the seed material. A variety of grain boundaries were obtained by varying the angle between the seeds. Microstructural studies indicate that the extent of residual melt deposited at the grain boundary decreases with increasing grain boundary contact angle. It is established that the growth front proceeds continuously at the (110)/(110) grain boundary without trapping liquid, which leads to the formation of a clean grain boundary

    Development of combi-pills using the coupling of semi-solid syringe extrusion 3D printing with fused deposition modelling

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    Data availability: Data will be made available on request.Copyright © 2022 The Authors. Three-dimensional (3D) printing allows for the design and printing of more complex designs than traditional manufacturing processes. For the manufacture of personalised medicines, such an advantage could enable the production of personalised drug products on demand. In this study, two types of extrusion-based 3D printing techniques, semi-solid syringe extrusion 3D printing and fused deposition modelling, were used to fabricate a combi-layer construct (combi-pill). Two model drugs, tranexamic acid (water soluble, rapid release) and indomethacin (poorly water-soluble, extended release), were printed with different geometries and materials compositions. Fourier transform infrared spectroscopy results showed that there were no interactions detected between drug-drug and drug-polymers. The printed combi-pills demonstrated excellent abrasion resisting properties in friability tests. The use of different functional excipients demonstrated significant impact on in vitro drug release of the model drugs incorporated in two 3D printed layers. Tranexamic acid and indomethacin were successfully 3D printed as a combi-pill with immediate-release and sustained-release profiles, respectively, to target quick anti-bleeding and prolonged anti-inflammation functions. For the first time, this paper systematically demonstrates the feasibility of coupling syringe-based extrusion 3D printing and fused deposition modelling as an innovative platform for various drug therapy productions, facilitating a new era of personalised combi-pills development.Redistributed Manufacturing in Healthcare Network (RiHN). The RiHN was awarded a grant from the UK Engineering and Physical Sciences Research Council (EPSRC) (Ref. EP/T014970/1)
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