567 research outputs found
Electrofusion welding and reinforced thermoplastic pipes – A review
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
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
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
How do surgeons feel about the “Getting it Right First Time” national audit? Results from a qualitative assessment.
The implementation of thenational“Getting It Right First Time” (GIRFT)was assessed by interviewing six surgeonsinvolvedat various levelsinsurgical site infection (SSI) audit.The positive impacts were to create new professional collaboration, improve stakeholder engagement, and increase the profile of SSIs. One particular knowledgegap highlighted was that some participantshad been unaware until that point of the criteria for diagnosing an SSI. The quality of data collected was felt poor due to methodological flaws. The audit was described as highly time-consuming and unsustainableif leaning on junior surgeons, without protectedtimeanddesignatedresponsibility
Soft robotic snake with variable stiffness actuation
© 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
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
Polymeric hole-transport materials with side-chain redox-active groups for perovskite solar cells with good reproducibility
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