892 research outputs found

    Rheological behaviour of different composite materials for additive manufacturing of 3D bone scaffolds

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    The production of scaffolds for bone tissue applications is requiring a combination of physical and biological properties, which are depending on the materials morphology and pro-cessing conditions during the production process. The aim of the paper is the investigation of rheological behaviour of polymer and composite blends regularly used for the production of scaffolds for bone tissue applications with the use of additive manufacturing. Poly-ε-caprolactone (PCL), hydroxyapatite (HA), β-tri-calcium phosphate (TCP) and Bioglass 45S5 blends containing different ceramic concentrations (10 wt%, 15 wt% and 20 wt%) were prepared with the use of melt blending procedure and investigated with the use of oscillation and rotational rheology tests. Results are showing that all blends are presenting viscoelastic behaviour with higher viscous modulus, compared with elastic modulus for low frequencies, with this difference reducing while the frequency is increasing. All blends are presenting shear-thinning behaviour suitable for use with additive manufacturing methods. Viscous and elastic modulus are increasing by adding ceramic particles. Results are presenting that PCL/HA blends of the same material concentration are presenting higher elastic modulus properties compared with the other blends, while PCL/Bioglass blends are presenting lower loss factor, lower relaxation time and lower shear viscosity making them easier to handle during the printing procedure

    Multi-layer Biosensor for Pre-symptomatic Detection of Puccinia strifformis, the Causal Agent of Yellow Rust

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    The yellow rust of wheat (caused by Puccinia striiformis f. sp. tritici) is a devastating fungal infection that is responsible for significant wheat yield losses. The main challenge with the detection of this disease is that it can only be visually detected on the leaf surface between 7 and 10 days after infection, and by this point, counter measures such as the use of fungicides are generally less effective. The hypothesis of this study is to develop and use a compact electrochemical-based biosensor for the early detection of P. striiformis, thus enabling fast countermeasures to be taken. The biosensor that was developed consists of three layers. The first layer mimics the wheat leaf surface morphology. The second layer consists of a sucrose/agar mixture that acts as a substrate and contains a wheat-derived terpene volatile organic compound that stimulates the germination and growth of the spores of the yellow rust pathogen P. s. f. sp. tritici. The third layer consists of a nonenzymatic glucose sensor that produces a signal once invertase is produced by P. striiformis, which comes into contact with the second layer, thereby converting sucrose to glucose. The results show the proof that this innovative biosensor can enable the detection of yellow rust spores in 72 h

    Polymer-ceramic bone bricks for tissue engineering

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    This paper investigates the use of polymer-ceramic composite scaffolds for bone regeneration. Different ratios between Poly-e-caprolactone (PCL) and Hydroxyapatite (HA) were considered. Scaffolds were produced using two different lay-down patterns (0/90° and 0/45°) and pore sizes (350μm, 500μm and 700μm). Compressive tests and cell proliferation tests are reported. Human adipose derived stem cells (hADSCs) were used for the biological characterization

    Anti-Müllerian Hormone Levels in Preeclampsia: A Systematic Review of the Literature

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    Objective: Serum Anti-Müllerian hormone (AMH) has been implicated in the pathogenesis of cardiovascular disease. Its prognostic value in determining the risk of developing preeclampsia remains, to date, unclear. The purpose of the present systematic review is to accumulate current evidence in this field. Materials and methods: We searched Medline (1966–2017), Scopus (2004–2017), Clinicaltrials.gov (2008–2017), EMBASE (1980-2017), LILACS (1986-2017) and Cochrane Central Register of Controlled Trials CENTRAL (1999-2017) databases. Results: Four studies were included in with a total number of 401 women. Among them 146 had preeclampsia while 232 were recruited as normotensive controls. Current data are suggestive of the potential predictive value of serum AMH as its levels seem to be lower among women that develop preeclampsia. One study reported that women with and AMH value below the 10th percentile of the studied population had a 3.3 increased risk of developing preeclampsia (OR 3.3, 95% CI 1.2–8.7, p = 0.01). Conclusion: Taking in mind these findings, future studies are needed in this field to establish optimal cut-off values and evaluate the specificity and sensitivity of this biomarker during the first trimester of pregnancy

    3D-printed composite bone bricks for large bone tissue applications

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    This study investigates the use of low cost, customizable, biodegradable, polymer-ceramic composite porous structures (bone bricks) for large bone tissue regeneration. Different ceramic materials (hydroxyapatite (HA), β-tri-calcium phosphate (TCP) and Bioglass (45S5) were mixed with poly-ε-caprolactone (PCL). Bone bricks with different material compositions were produced using an extrusion-based additive manufacturing system. Produced bone bricks were morphologically and mechanically assessed. Results allowed to establish a correlation between scaffolds architecture and material composition and scaffolds performance. Reinforced scaffolds showed improved mechanical properties. Best mechanical properties were obtained with PCL/TCP bone bricks and topologies based on 38 double zig zag filaments and 14 spirals

    Differential cross section measurements for the production of a W boson in association with jets in proton–proton collisions at √s = 7 TeV

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    Measurements are reported of differential cross sections for the production of a W boson, which decays into a muon and a neutrino, in association with jets, as a function of several variables, including the transverse momenta (pT) and pseudorapidities of the four leading jets, the scalar sum of jet transverse momenta (HT), and the difference in azimuthal angle between the directions of each jet and the muon. The data sample of pp collisions at a centre-of-mass energy of 7 TeV was collected with the CMS detector at the LHC and corresponds to an integrated luminosity of 5.0 fb[superscript −1]. The measured cross sections are compared to predictions from Monte Carlo generators, MadGraph + pythia and sherpa, and to next-to-leading-order calculations from BlackHat + sherpa. The differential cross sections are found to be in agreement with the predictions, apart from the pT distributions of the leading jets at high pT values, the distributions of the HT at high-HT and low jet multiplicity, and the distribution of the difference in azimuthal angle between the leading jet and the muon at low values.United States. Dept. of EnergyNational Science Foundation (U.S.)Alfred P. Sloan Foundatio

    Optimasi Portofolio Resiko Menggunakan Model Markowitz MVO Dikaitkan dengan Keterbatasan Manusia dalam Memprediksi Masa Depan dalam Perspektif Al-Qur`an

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    Risk portfolio on modern finance has become increasingly technical, requiring the use of sophisticated mathematical tools in both research and practice. Since companies cannot insure themselves completely against risk, as human incompetence in predicting the future precisely that written in Al-Quran surah Luqman verse 34, they have to manage it to yield an optimal portfolio. The objective here is to minimize the variance among all portfolios, or alternatively, to maximize expected return among all portfolios that has at least a certain expected return. Furthermore, this study focuses on optimizing risk portfolio so called Markowitz MVO (Mean-Variance Optimization). Some theoretical frameworks for analysis are arithmetic mean, geometric mean, variance, covariance, linear programming, and quadratic programming. Moreover, finding a minimum variance portfolio produces a convex quadratic programming, that is minimizing the objective function ðð¥with constraintsð ð 𥠥 ðandð´ð¥ = ð. The outcome of this research is the solution of optimal risk portofolio in some investments that could be finished smoothly using MATLAB R2007b software together with its graphic analysis

    Juxtaposing BTE and ATE – on the role of the European insurance industry in funding civil litigation

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    One of the ways in which legal services are financed, and indeed shaped, is through private insurance arrangement. Two contrasting types of legal expenses insurance contracts (LEI) seem to dominate in Europe: before the event (BTE) and after the event (ATE) legal expenses insurance. Notwithstanding institutional differences between different legal systems, BTE and ATE insurance arrangements may be instrumental if government policy is geared towards strengthening a market-oriented system of financing access to justice for individuals and business. At the same time, emphasizing the role of a private industry as a keeper of the gates to justice raises issues of accountability and transparency, not readily reconcilable with demands of competition. Moreover, multiple actors (clients, lawyers, courts, insurers) are involved, causing behavioural dynamics which are not easily predicted or influenced. Against this background, this paper looks into BTE and ATE arrangements by analysing the particularities of BTE and ATE arrangements currently available in some European jurisdictions and by painting a picture of their respective markets and legal contexts. This allows for some reflection on the performance of BTE and ATE providers as both financiers and keepers. Two issues emerge from the analysis that are worthy of some further reflection. Firstly, there is the problematic long-term sustainability of some ATE products. Secondly, the challenges faced by policymakers that would like to nudge consumers into voluntarily taking out BTE LEI
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