519 research outputs found

    Electrofusion welding and reinforced thermoplastic pipes – A review

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    Oil and gas operators have been looking for a more reliable and cost-effective material for their pipelines to substitute steel in pipes and connectors. Reinforced thermoplastic pipes are a popular choice for this purpose, but they are still mainly using steel connectors, which have limited lifetimes due to corrosion. For this reason, efforts are being made to design a non-metallic electrofusion coupler to connect these. This article looks at the current state of the art in electrofusion welding of standard polyethylene pipes and aims to find possibilities of applying this technology to reinforced thermoplastic pipes

    The effect of laser power, traverse velocity and spot size on the peel resistance of a polypropylene/adhesive bond

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    Abstract The mean peel resistance force achieved with respect to variation in the laser power, incident spot traverse velocity and incident spot diameter between linear low density polyethylene film backed by a thin commercial adhesive coating that were bonded to a polypropylene substrate via thermal activation provided by a 27W CO 2 laser is discussed in this work. The results gathered for this work have been used to generate a novel empirical tool that predicts the CO 2 laser power required to achieve a viable adhesive bond for this material combination. This predictive tool will enable the packaging industry to achieve markedly increased financial yield, process efficiency, reduced material waste and process flexibility. A laser spot size dependent linear increase in laser line energy was necessary for this material combination, suggesting the minimal impact of thermal strain rate. Moreover a high level of repeatability around this threshold laser line energy was indicated, suggesting that laser activated adhesive bonding of such polymer films is viable. The adhesion between the material combination trialled here responded linearly to thermal load. In particular, when using the smallest diameter laser spot, it is proposed that the resulting high irradiance caused film or adhesive material damage; thus, resulting in reduced peel resistance force. The experimental work conducted indicated that the processing window of an incident CO 2 laser spot increases with respect to spot diameter, simultaneously yielding greater bond stability in the face of short-term laser variance

    Airway microbiome in adult survivors of extremely preterm birth: the EPICure study

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    Bronchopulmonary Dysplasia(BPD) is a major complication of preterm birth that leads to lifelong respiratory morbidity. The EPICure study has investigated the longitudinal health outcomes of infants born extremely preterm (<26 weeks-gestation). Our aim was to characterise the airway microbiome in young adults born extremely preterm (EP), with and without neonatal BPD, in comparison to matched term-born controls.Induced sputum was collected from 92 young adults age 19 years (51 EP and 41 controls). Typical respiratory pathogens were detected using quantitative-PCR. 16S-rRNA gene sequencing was completed on 74 samples (29 EP with BPD, 9 EP without BPD and 36 controls).The preterm group with BPD had the least diverse bacterial communities. The relative-abundance of Bacteriodetes, particularly Prevotella melaninogenica was significantly lower in the preterm group compared to controls. This decline was balanced by a nonsignificant increase in Firmicutes. Total Prevotella relative-abundance correlated with FEV1 z-score (ρ=0.272; p<0.05). Typical respiratory pathogens loads and prevalence were similar between groups.In conclusion, extremely preterm birth is associated with a significant dysbiosis in airway microbiome in young adulthood regardless of neonatal BPD status. This is characterised by a shift in the community composition away from Bacteriodetes as manifested in a significant drop in Prevotella relative-abundance

    Soft robotic snake with variable stiffness actuation

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    © Springer International Publishing AG 2017. In this paper, we present a prototype of a 3D printed snake-like robot for search and rescue applications, inspired by biological snake anatomy and locomotion. Unlike traditional robotics, this design takes advantage of soft materials to create a robot that is resilient to shock impacts, such as from falling debris or unsound flooring, and that can very its stiffness. The robot uses a flexible spine to connect multiple sections, allowing controlled actuation while providing a sturdy structure. Variable stiffness actuation is implemented through the use of elastic materials to act as tendons for the body, in an agonist-antagonist setup. Actuation occurs through the use of Robotis Dynamixel AX-12A servos, controlled by a Trossen Robotics Arbotix-M Robocon-troller. The design features a head, containing a Raspberry Pi 3 and a Pi Camera Module. This added embedded computation can connect to a remote PC via wireless communication, allowing an operator to control the robot. This paper discusses the design and early stage testing for the prototype, and shows that robots based on soft 3D printed materials and mechanisms are viable, and effective

    Star-shaped triarylamine-based hole-transport materials in perovskite solar cells

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    Two novel star-shaped triarylamine-based hole transport materials with triphenylamine (STR1), or a partially oxygen-bridged triphenylamine (STR0), as core and para-substituted triphenylamine side arms were synthesized, fully characterized and studied in perovskite solar cells. Their thermal, optical, electrochemical and charge transport properties were examined and compared in the context of their molecular structure. Due to its more planar configuration, STR0 showed a red-shifted absorption in comparison with STR1. STR0 also forms a more stable amorphous glassy state and showed higher glass transition temperature than STR1 and spiro-OMeTAD. These HTMs were tested in perovskite solar cells using a device configuration of FTO/bl-TiO2/mp-TiO2/CH3NH3PbI3/HTM/Au showing a power conversion efficiency of 13.3% for STR0 and 11.5% for STR1. The STR0-based devices showed higher fill factor and better reproducibility than spiro-OMeTAD-based cells. Without dopant additives, solar cells based on STR0 exhibited a good photocurrent density of 16.63 mA cm−2 and the efficiency improved from a starting PCE of 3.9% to 6.6% after two weeks of storage

    Variability of NT-proBNP and Its Relationship with Inflammatory Status in Patients with Stable Essential Hypertension: A 2-Year Follow-Up Study

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    The variability of NT-proBNP levels has been studied in heart failure, yet no data exist on these changes over time in hypertensive patients. Furthermore, studies on the relationship between natriuretic peptides and inflammatory status are limited.220 clinically and functionally asymptomatic stable patients (age 59 ± 13, 120 male) out of 252 patients with essential hypertension were followed up, and NT-proBNP was measured at baseline, 12 and 24 months. No differences in NT-proBNP were found with respect to the basal stage in the hypertrophic group, but significant changes were found in non-hypertrophic subjects. The reproducibility of NT-proBNP measurements was better in patients with hypertrophy than in the non-hypertrophic group for the three intervals (stage I-basal; stage II-stage I; stage II-basal) with a reference change value of 34%, 35% and 41%, respectively, in the hypertrophic group. A more elevated coefficient of correlation was obtained in the hypertrophic group than in patients without hypertrophy: basal versus stage I (r = 0.79, p < 0.0001 and r = 0.59, p < 0.0001) and stage I versus stage II (r = 0.86, p < 0.0001 and r = 0.56, p < 0.0001). Finally, levels of NT-proBNP significantly correlated with sTNF-R1 (p < 0.0001) and IL-6 (p < 0.01) during follow-up. A multivariate linear regression analysis showed that sTNF-R1 is an independent factor of NT-proBNP.This work shows that there is good stability in NT-proBNP levels in a follow-up study of asymptomatic patients with stable hypertension and left ventricular hypertrophy. As a consequence, assessment of NT-proBNP concentrations may be a useful tool for monitoring the follow-up of hypertensive patients with hypertrophy. Measured variations in peptide levels, exceeding 35% in a 12-month follow-up and 41% in a 24-month follow-up, may indicate an increase in cardiovascular risk, and therefore implies adjustment in the medical treatment. In addition, this study shows a link between neurohormonal and inflammatory activation in these patients

    Rapid Rule-out of Acute Myocardial Infarction With a Single High-Sensitivity Cardiac Troponin T Measurement Below the Limit of Detection: A Collaborative Meta-analysis.

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    Background: High-sensitivity assays for cardiac troponin T (hs-cTnT) are sometimes used to rapidly rule out acute myocardial infarction (AMI). Purpose: To estimate the ability of a single hs-cTnT concentration below the limit of detection (<0.005 ”g/L) and a nonischemic electrocardiogram (ECG) to rule out AMI in adults presenting to the emergency department (ED) with chest pain. Data Sources: EMBASE and MEDLINE without language restrictions (1 January 2008 to 14 December 2016). Study Selection: Cohort studies involving adults presenting to the ED with possible acute coronary syndrome in whom an ECG and hs-cTnT measurements were obtained and AMI outcomes adjudicated during initial hospitalization. Data Extraction: Investigators of studies provided data on the number of low-risk patients (no new ischemia on ECG and hs-cTnT measurements <0.005 ”g/L) and the number who had AMI during hospitalization (primary outcome) or a major adverse cardiac event (MACE) or death within 30 days (secondary outcomes), by risk classification (low or not low risk). Two independent epidemiologists rated risk of bias of studies. Data Synthesis: Of 9241 patients in 11 cohort studies, 2825 (30.6%) were classified as low risk. Fourteen (0.5%) low-risk patients had AMI. Sensitivity of the risk classification for AMI ranged from 87.5% to 100% in individual studies. Pooled estimated sensitivity was 98.7% (95% CI, 96.6% to 99.5%). Sensitivity for 30-day MACEs ranged from 87.9% to 100%; pooled sensitivity was 98.0% (CI, 94.7% to 99.3%). No low-risk patients died. Limitation: Few studies, variation in timing and methods of reference standard troponin tests, and heterogeneity of risk and prevalence of AMI across studies. Conclusion: A single hs-cTnT concentration below the limit of detection in combination with a nonischemic ECG may successfully rule out AMI in patients presenting to EDs with possible emergency acute coronary syndrome. Primary Funding Source: Emergency Care Foundation
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