1,081 research outputs found
Varying CFRP workpiece temperature during slotting : effects on surface metrics, cutting forces and chip geometry
Carbon fibre reinforced thermoset polymer (CFRP) components are typically edge trimmed using a milling process to achieve final part shape. During this process the material is subject to significant heating at the tool-workpiece interface. Damage due to heating is fibre orientation specific; for some orientations it can lead to matrix smearing, potentially hiding defects and for others it can increase pullout. Understanding these relationships is critical to attaining higher throughput by edge milling. For the first time this study focuses on active heating of the CFRP rather than passive measurement, through use of a thermocouple controlled system to heat a CFRP workpiece material from room temperature (RT) up to 110 °C prior to machining. Differences in cutting mechanisms for fibres oriented at 0, 45, 90 and -45° are observed with scanning electron microscopy (SEM), and quantified with using focus variation with an increase of 89.9% Sa reported between RT and 110°C CFRP panel pre-heating. Relationships to cutting forces through dynamometer readings and tool temperature through infra-red (IR) measurements are also made with a novel optical method to measure cut chips presented. Results show an increase in chip length and width for increasing cutting temperature from RT to 110°C (3.39 and 0.79 µm for length and width, respectively). This work improves current understandings of how the cutting mechanism changes with increased temperature and suggests how improved milling throughput can be achieved
Epifluorescent microscopy of edge-trimmed carbon fibre-reinforced polymers : an alternative to computed tomography scanning
X-Ray computed tomography (XCT) can be used to detect edge-milled carbon fibre-reinforced polymer (CFRP) defects. Significantly this method is able to show subsurface defects that cannot be captured by traditional methods such as stylus-based or more novel areal methods of surface quality measurement. While useful, this method can be prohibitive due to high equipment cost, scanning time and image resolution. XCT can often produce artefacts which falsely predict damage or obscure damage and depending on machine X-ray power often cannot resolve damage to fibre diameter which is critical when observing milled quality of the surface/subsurface. This study utilises epifluorescent (EF) optical microscopy to provide high-quality optical images as an alternative to XCT to observe through-depth damage of CFRP materials. The method of computing the novel damage criteria is presented, as well as the validation of the method which compares EF to XCT. Subsurface damage of fabric and unidirectional (UD) materials in 0°, 45°, 90° and −45° orientations to the cutting edge is observed to demonstrate typical defects. A novel metric resulting from the EF method provides a total area of damage when compared to a theoretically straight cut across the face of the edge-milled CFRP. The method shows that different subsurface damage exists for different fibre orientations to the cutting edge, highlighting the clear need for through-depth analysis of machined edges. In addition, the method is shown to be a suitable alternative to XCT with scope for further development of industrial aerospace and automotive quality control of machined CFRP parts
The rate of hypo-osmotic challenge influences regulatory volume decrease (RVD) and mechanical properties of articular chondrocytes
Zhao Wang is funded on a China Scholarships PhD Studentship. Jerome Irianto was supported on a project grant from The Wellcome Trust (ref no. 084717)
Activation of the innate immune receptor Dectin-1 upon formation of a 'phagocytic synapse'.
Innate immune cells must be able to distinguish between direct binding to microbes and detection of components shed from the surface of microbes located at a distance. Dectin-1 (also known as CLEC7A) is a pattern-recognition receptor expressed by myeloid phagocytes (macrophages, dendritic cells and neutrophils) that detects β-glucans in fungal cell walls and triggers direct cellular antimicrobial activity, including phagocytosis and production of reactive oxygen species (ROS). In contrast to inflammatory responses stimulated upon detection of soluble ligands by other pattern-recognition receptors, such as Toll-like receptors (TLRs), these responses are only useful when a cell comes into direct contact with a microbe and must not be spuriously activated by soluble stimuli. In this study we show that, despite its ability to bind both soluble and particulate β-glucan polymers, Dectin-1 signalling is only activated by particulate β-glucans, which cluster the receptor in synapse-like structures from which regulatory tyrosine phosphatases CD45 and CD148 (also known as PTPRC and PTPRJ, respectively) are excluded (Supplementary Fig. 1). The 'phagocytic synapse' now provides a model mechanism by which innate immune receptors can distinguish direct microbial contact from detection of microbes at a distance, thereby initiating direct cellular antimicrobial responses only when they are required
Verbal autopsy-assigned causes of death among adults being investigated for TB in South Africa
Aaron S. Karat - ORCID 0000-0001-9643-664X
https://orcid.org/0000-0001-9643-664XBackground: Adults being investigated for TB in South Africa experience high mortality, yet causes of death
(CoD) are not well defined. We determined CoD in this population using verbal autopsy (VA), and compared
HIV- and TB-associated CoD using physician-certified verbal autopsy (PCVA) and InterVA-4 software.Methods: All contactable consenting caregivers of participants who died during a trial comparing Xpert MTB/
RIF to smear microscopy were interviewed using the WHO VA tool. CoD were assigned using PCVA and
InterVA-4. Kappa statistic (K) and concordance correlation coefficient (CCC) were calculated for comparison.Results: Among 231 deaths, relatives of 137 deceased were interviewed. Of the 137 deceased 76 (55.4%)
were males, median age 41 years (IQR 33–50). PCVA assigned 70 (51.1%) TB immediate CoD (44 [62.8%] pulmonary TB; 26 [37.1%] extra-pulmonary TB); 21 (15.3%) HIV/AIDS-related; and 46 (33.5%) other CoD.
InterVA-4 assigned 48 (35.0%) TB deaths; 49 (35.7%) HIV/AIDS-related deaths; and 40 (29.1%) other CoD.
Agreement between PCVA and InterVA-4 CoD was slight at individual level (K=0.20; 95% CI 0.10–0.30) and
poor at population level (CCC 0.67; 95% CI 0.38–0.99).Conclusions: TB and HIV are leading CoD among adults being investigated for TB. PCVA and InterVA agreement at individual level was slight and poor at population level. VA methodology needs further development
where TB and HIV are common.This work was supported by Bill & Melinda Gates Foundation [Grant Number: OPP1034523] for funding the study.https://doi.org/10.1093/trstmh/trw058110pubpub
Effects of tool coating and tool wear on the surface quality and flexural strength of slotted CFRP
Machining of carbon fibre reinforced polymer (CFRP) is abrasive and causes significant tool wear. The effect of tool wear on static flexural strength is investigated, using edge trimming with uncoated carbide and chemical vapour deposition (CVD) diamond coated burr style tools. Edge rounding (ER) criteria along with flank wear are used to observe tool degradation with ER shown to preferentially wear allowing the tool to become cyclically sharper and duller, corresponding to fluctuating dynamometer readings, a novelty for CFRP machining. Areal surface metrics degraded for an uncoated tool due to changes in cutting mechanism, whilst for up to 16.2 m of linear traverse, the coated tool showed limited changes. Tool wear, caused by edge trimming 7.2 m of CFRP, using an uncoated carbide tool, provided a flexural strength reduction of up to 10.5 %, directly linking tool wear to reduced mechanical strength
Novel anti-inflammatory and chondroprotective effects of the human melanocortin MC1 receptor agonist BMS-470539 dihydrochloride and human melanocortin MC3 receptor agonist PG-990 on lipopolysaccharide activated chondrocytes
Human melanocortin MC1 and MC3 receptors expressed on C-20/A4 chondrocytes exhibit chondroprotective and anti-inflammatory effects when activated by melanocortin peptides. Nearly 9 million people in the UK suffer from osteoarthritis, and bacterial infections play a role in its development. Here, we evaluate the effect of a panel of melanocortin peptides with different selectivity for human melanocortin MC1 (α-MSH, BMS-470539 dihydrochloride) and MC3 ([DTrp8]-γ-MSH, PG-990) receptors and C-terminal peptide α-MSH11-13(KPV), on inhibiting LPS-induced chondrocyte death, pro-inflammatory mediators and induction of anti-inflammatory proteins. C-20/A4 chondrocytes were treated with a panel of melanocortin peptides prophylactically and therapeutically in presence of LPS (0.1 μg/ml). The chondroprotective properties of these peptides determined by cell viability assay, RT-PCR, ELISA for detection of changes in inflammatory markers (IL-6, IL-8 and MMP-1, -3 and -13) and western blotting for expression of the anti-inflammatory protein heme-oxygenase-1. C-20/A4 expressed human melanocortin MC1 and MC3 receptors and melanocortin peptides elevated cAMP. LPS stimulation caused a reduction in C-20/A4 viability, attenuated by the human melanocortin MC1 receptor agonist BMS-470539 dihydrochloride, and MC3 receptor agonists PG-990 and [DTrp8]-γ-MSH. Prophylactic and therapeutic regimes of [DTrp8]-γ-MSH significantly inhibited LPS-induced modulation of cartilage-damaging IL-6, IL-8, MMPs −1,-3 and −13 mediators both prophylactically and therapeutically, whilst human melanocortin MC1 and MC3 receptor agonists promoted an increase in HO-1 production. In the presence of LPS, activation of human melanocortin MC1 and MC3 receptors provided potent chondroprotection, upregulation of anti-inflammatory proteins and downregulation of inflammatory and proteolytic mediators involved in cartilage degradation, suggesting a new avenue for osteoarthritis treatment
Confined magnon dispersion in ferromagnetic and antiferromagnetic thin films in a second quantization approach: the case of Fe and NiO
We present a methodology based on the calculation of the inelastic scattering
from magnons via the spin scattering function in confined geometries such as
thin films using a second quantization formalism, for both ferromagnetic and
antiferromagnetic materials. The case studies are chosen with an aim to
demonstrate the effects of film thickness and crystal orientation on magnon
modes, using bcc Fe(100) and NiO with (100) and (111) crystallographic
orientations as prototypical systems. Due to the quantization of the
quasi-momentum we observe a granularity in the inelastic spectra in the
reciprocal space path reflecting the orientation of the thin film. This
approach also allows to capture softer modes that appear due to the partial
interaction of magnetic moments close to the surface in a thin film geometry,
in addition to bulk modes. The softer modes are also affected by
crystallographic orientations as illustrated by the different surface-related
peaks of NiO magnon density of states at approximately ~ 65 meV for (100) and ~
42 meV for (111). Additionally, we explore the role of anisotropy on magnon
modes, revealing that introducing anisotropy to both Fe and NiO films increases
the overall hardness of the magnon modes. The introduction of a surface
anisotropy produces a shift of the surface-related magnon DOS peak to higher
energies with increased surface anisotropy, and in some cases leading to
surface confined mode
Screenwriting as a mode of research, and the screenplay as a research artefact
Screenwriting practice is now a flourishing mode of research within universities internationally, whereby the act of writing a screenplay or developing screenplay works is not only understood, but also celebrated as a legitimate form of knowledge discovery and dissemination. The resulting work of this creative practice research, which we might call the 'academic screenplay', thus functions simultaneously as a method of research enquiry and a 'non traditional' research artefact. In this chapter we explore what it means to develop and write a screenplay in the academy, under the conditions of and for research. By positioning screenwriting alongside and in between the disciplines of creative writing and screen production, we reflect on how it can draw from both disciplines at different times and for different purposes, and can be influenced by their specific - and sometimes contradictory - discourses. By doing so, the chapter provides a comprehensive overview of screenwriting as a growing mode of research, and its practice as an important addition to the academy
Theory of momentum-resolved magnon electron energy loss spectra: The case of Yttrium Iron Garnet
We explore the inelastic spectra of electrons impinging in a magnetic system.
The methodology here presented is intended to highlight the charge-dependent
interaction of the electron beam in a STEM-EELS experiment, and the local
vector potential generated by the magnetic lattice. This interaction shows an
intensity smaller than the purely spin interaction, which is taken to
be functionally the same as in the inelastic neutron experiment. On the other
hand, it shows a strong scattering vector dependence () and a
dependence with the relative orientation between the probe wavevector and the
local magnetic moments of the solid. We present YIG as a case study due to its
high interest by the community
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