Now showing items 1-20 of 6768

    • Rapid compensatory evolution can rescue low fitness symbioses following partner switching.

      Sørensen, Megan E S; Wood, A Jamie; Cameron, Duncan D; Brockhurst, Michael A; email: michael.brockhurst@manchester.ac.uk (2021-07-01)
      Partner switching plays an important role in the evolution of symbiosis, enabling local adaptation and recovery from the breakdown of symbiosis. Because of intergenomic epistasis, partner-switched symbioses may possess novel combinations of phenotypes but may also exhibit low fitness due to their lack of recent coevolutionary history. Here, we examine the structure and mechanisms of intergenomic epistasis in the Paramecium-Chlorella symbiosis and test whether compensatory evolution can rescue initially low fitness partner-switched symbioses. Using partner-switch experiments coupled with metabolomics, we show evidence for intergenomic epistasis wherein low fitness is associated with elevated symbiont stress responses either in dark or high irradiance environments, potentially owing to mismatched light management traits between the host and symbiont genotypes. Experimental evolution under high light conditions revealed that an initially low fitness partner-switched non-native host-symbiont pairing rapidly adapted, gaining fitness equivalent to the native host-symbiont pairing in less than 50 host generations. Compensatory evolution took two alternative routes: either hosts evolved higher symbiont loads to mitigate for their new algal symbiont's poor performance, or the algal symbionts themselves evolved higher investment in photosynthesis and photoprotective traits to better mitigate light stress. These findings suggest that partner switching combined with rapid compensatory evolution can enable the recovery and local adaptation of symbioses in response to changing environments. [Abstract copyright: Copyright © 2021 Elsevier Inc. All rights reserved.]
    • Calcium signaling in neuroglia.

      Lim, Dmitry; email: dmitry.lim@uniupo.it; Semyanov, Alexey; Genazzani, Armando; Verkhratsky, Alexei; email: alexej.verkhratsky@manchester.ac.uk (2021-04-10)
      Glial cells exploit calcium (Ca ) signals to perceive the information about the activity of the nervous tissue and the tissue environment to translate this information into an array of homeostatic, signaling and defensive reactions. Astrocytes, the best studied glial cells, use several Ca signaling generation pathways that include Ca entry through plasma membrane, release from endoplasmic reticulum (ER) and from mitochondria. Activation of metabotropic receptors on the plasma membrane of glial cells is coupled to an enzymatic cascade in which a second messenger, InsP is generated thus activating intracellular Ca release channels in the ER endomembrane. Astrocytes also possess store-operated Ca entry and express several ligand-gated Ca channels. In vivo astrocytes generate heterogeneous Ca signals, which are short and frequent in distal processes, but large and relatively rare in soma. In response to neuronal activity intracellular and inter-cellular astrocytic Ca waves can be produced. Astrocytic Ca signals are involved in secretion, they regulate ion transport across cell membranes, and are contributing to cell morphological plasticity. Therefore, astrocytic Ca signals are linked to fundamental functions of the central nervous system ranging from synaptic transmission to behavior. In oligodendrocytes, Ca signals are generated by plasmalemmal Ca influx, or by release from intracellular stores, or by combination of both. Microglial cells exploit Ca permeable ionotropic purinergic receptors and transient receptor potential channels as well as ER Ca release. In this contribution, basic morphology of glial cells, glial Ca signaling toolkit, intracellular Ca signals and Ca -regulated functions are discussed with focus on astrocytes. [Abstract copyright: Copyright © 2021 Elsevier Inc. All rights reserved.]
    • Impacts of COVID-19 and social isolation on academic staff and students at universities: a cross-sectional study.

      Leal Filho, Walter; orcid: 0000-0002-3993-8974; email: walter.leal2@haw-hamburg.de; Wall, Tony; Rayman-Bacchus, Lez; Mifsud, Mark; Pritchard, Diana J; Lovren, Violeta Orlovic; orcid: 0000-0002-2678-3256; email: violeta.orlovic@f.bg.ac.rs; Farinha, Carla; Petrovic, Danijela S; Balogun, Abdul-Lateef (2021-06-24)
      <h4>Background</h4>"The impacts of the Coronavirus Disease 2019 (COVID-19) pandemic and the shutdown it triggered at universities across the world, led to a great degree of social isolation among university staff and students. The aim of this study was to identify the perceived consequences of this on staff and their work and on students and their studies at universities.<h4>Method</h4>The study used a variety of methods, which involved an on-line survey on the influences of social isolation using a non-probability sampling. More specifically, two techniques were used, namely a convenience sampling (i.e. involving members of the academic community, which are easy to reach by the study team), supported by a snow ball sampling (recruiting respondents among acquaintances of the participants). A total of 711 questionnaires from 41 countries were received. Descriptive statistics were deployed to analyse trends and to identify socio-demographic differences. Inferential statistics were used to assess significant differences among the geographical regions, work areas and other socio-demographic factors related to impacts of social isolation of university staff and students.<h4>Results</h4>The study reveals that 90% of the respondents have been affected by the shutdown and unable to perform normal work or studies at their institution for between 1 week to 2 months. While 70% of the respondents perceive negative impacts of COVID 19 on their work or studies, more than 60% of them value the additional time that they have had indoors with families and others. .<h4>Conclusions</h4>While the majority of the respondents agree that they suffered from the lack of social interaction and communication during the social distancing/isolation, there were significant differences in the reactions to the lockdowns between academic staff and students. There are also differences in the degree of influence of some of the problems, when compared across geographical regions. In addition to policy actions that may be deployed, further research on innovative methods of teaching and communication with students is needed in order to allow staff and students to better cope with social isolation in cases of new or recurring pandemics.
    • Veteran help-seeking behaviour for mental health issues: a systematic review.

      Randles, Rebecca; orcid: 0000-0002-7401-5817; Finnegan, A; orcid: 0000-0002-2189-4926; email: a.finnegan@chester.ac.uk (2021-07-12)
      Serving military personnel and veterans have been identified to have a high prevalence of mental health disorders. Despite this, only a significantly small number seek mental healthcare. With the UK beginning to invest further support to the armed forces community, identification of barriers and facilitators of help-seeking behaviour is needed. Corresponding literature search was conducted in PsycINFO, PsycArticles, Medline, Web of Science and EBSCO. Articles which discussed barriers and facilitators of seeking help for mental health concerns in the veteran population were included. Those which discussed serving personnel or physical problems were not included within this review. A total of 26 papers were analysed. A number of barriers and facilitators of help-seeking for a mental health issue within the veteran population were identified. Barriers included stigma, military culture of stoicism and self-reliance, as well as deployment characteristics of combat exposure and different warzone deployments. Health service difficulties such as access and lack of understanding by civilian staff were also identified. Facilitators to help combat these barriers included a campaign to dispel the stigma, including involvement of veterans and training of military personnel, as well as more accessibility and understanding from healthcare staff. While some barriers and facilitators have been identified, much of this research has been conducted within the USA and on male veterans and lacks longitudinal evidence. Further research is needed within the context of other nations and female veterans and to further indicate the facilitators of help-seeking among veterans. [Abstract copyright: © Author(s) (or their employer(s)) 2021. No commercial re-use. See rights and permissions. Published by BMJ.]
    • Patient preferences and priorities for haemophilia gene therapy in the US: A discrete choice experiment

      Witkop, Michelle; Morgan, George; orcid: 0000-0003-2014-3415; email: george.morgan@hcdeconomics.com; O'Hara, Jamie; Recht, Michael; Buckner, Tyler W.; Nugent, Diane; Curtis, Randall; orcid: 0000-0002-6859-6432; O'Mahony, Brian; orcid: 0000-0001-9780-6972; Skinner, Mark W.; orcid: 0000-0002-0934-0680; Mulhern, Brendan; et al. (2021-07-26)
      Abstract: Introduction: Gene therapy has shown promise in clinical trials for patients with haemophilia, but patient preference studies have focused on factor replacement treatments. Aim: We conducted a discrete choice experiment (DCE) to investigate the relative importance and differential preferences patients provide for gene therapy attributes. Methods: We surveyed male adults with haemophilia in the United States recruited from patient panels including the National Hemophilia Foundation Community Voices in Research platform using an online survey over 4 months in 2020/21. Participants indicated preferences for gene therapy attributes including dosing frequency/durability, effect on annual bleeding, uncertainty related to side effects, impact on daily activities, impact on mental health, and post‐treatment requirements. The relative importance of each attribute was analysed overall and for subgroups based on haemophilia type and severity. Results: A total of 183 males with haemophilia A (n = 120) or B (n = 63) were included. Half (47%) had severe haemophilia; most (75%) were White. Overall, participants gave effect on bleeding rate the greatest relative importance (31%), followed by dose frequency/durability (26%), uncertainty regarding safety issues (17%), and impact on daily activities (11%). Dose frequency/durability had the greatest importance for those with haemophilia B (35%). Conclusion: People with haemophilia prioritised reduced bleeding and treatment burden; the former was more important in haemophilia A and the latter in haemophilia B, followed by safety and impact on daily life in this DCE of gene therapy attributes. These findings and differences can inform clinical and health policy decisions to improve health equity for people with haemophilia.
    • Chronic and rare disease patients' access to healthcare services during a health crisis: The example of the COVID‐19 pandemic in Turkey

      Aktas, Puren; orcid: 0000-0003-0783-8044; email: puren.aktas@postgrad.manchester.ac.uk (2021-07-26)
      Abstract: Objective: The restructuring of healthcare provision for the coronavirus disease 2019 (COVID‐19) pandemic caused disruptions in access for patients with chronic or rare diseases. This study explores the experiences of patients with chronic or rare diseases in access to healthcare services in Turkey during the COVID‐19 pandemic. Methods: Semi‐structured interviews were conducted with representatives (n = 10) of patient organisations (n = 9) based in Istanbul. Thematic analysis with an inductive approach was conducted to analyse the responses obtained through the interviews. Results: The lack of clinical information at the beginning of the pandemic caused fear among patients with chronic or rare diseases. Patients experienced obstacles in access to healthcare services because of the overcrowding of hospitals with COVID‐19 patients. Some treatment procedures were cancelled or postponed by physicians. Of these procedures, some were medically vital for those patients, leading to or exacerbating further health problems. The most positive measures that patients identified were where the Social Security Institution introduced regulations to facilitate access to prescribed medicine for chronic patients. Information exchange between the doctors and their patients was important to alleviate the uncertainty and reduce the anxiety among patients. Discussion: Access problems experienced by patients during the COVID‐19 pandemic were a complex mix of factors including shortages and physical barriers, but also perceptions of barriers. The findings of this study show that patient organisations can provide insights on disease‐specific experiences and problems that are very valuable to improve access to healthcare services to achieve the universal health coverage target. Hence, this study emphasises the inclusion of patient organisations in decision‐making processes during times of health crises. Public Contribution: Representatives of patient organisations participated in the interviews.
    • Evaluation of the Feasibility, Reliability, and Repeatability of Welfare Indicators in Free-Roaming Horses: A Pilot Study.

      Harley, Jessica; Stack, J.D.; Braid, H; McLennan, Krista M.; Stanley, Christina; University of Chester; University of Liverpool
      Validated assessment protocols have been developed to quantify welfare states for intensively managed sport, pleasure, and working horses. There are few protocols for extensively managed or free-roaming populations. Here, we trialed welfare indicators to ascertain their feasibility, reliability, and repeatability using free-roaming Carneddau Mountain ponies as an example population. The project involved (1) the identification of animal and resource-based measures of welfare from both the literature and discussion with an expert group; (2) testing the feasibility and repeatability of a modified body condition score and mobility score on 34 free-roaming and conservation grazing Carneddau Mountain ponies; and (3) testing a prototype welfare assessment template comprising 12 animal-based and 6 resource-based welfare indicators, with a total of 20 questions, on 35 free-roaming Carneddau Mountain ponies to quantify inter-assessor reliability and repeatability. This pilot study revealed that many of the indicators were successfully repeatable and had good levels of inter-assessor reliability. Some of the indicators could not be verified for reliability due to low/absent occurrence. The results indicated that many animal and resource-based indicators commonly used in intensively managed equine settings could be measured in-range with minor modifications. This study is an initial step toward validating a much-needed tool for the welfare assessment of free-roaming and conservation grazing ponies.
    • Optomechanical switching of adsorption configurations of polar organic molecules by UV radiation pressure

      Arumugam, Kowsalya; Papadopoulos, Theodoros; Tang, Shu-Jung; National Tsing Hua University; Tokyo University of Science; National Synchrotron Radiation Research Center (NSRRC); University of Chester
      Using photoemission spectroscopy (PES), we have systematically investigated the behavior of polar organic molecule, chloroaluminum phthalocyanine (ClAlPc), adsorbed in the Cl-down configuration on the Ag(111) substrate at low temperature − 195 °C under UV irradiation with a range of different photon fluxes. Judging from the evolution of photoemission spectral line shapes of molecular energy states, we discovered that the Cl atoms are so robustly anchored at Ag(111) that the impinging photons cannot flip the ClAlPc molecules, but instead they crouch them down due to radiation pressure; we observe that the phthalocyanine (Pc) lobes bend down to interact with Ag atoms on the substrate and induce charge transfer from them. As photon flux is increased, radiation pressure on the Pc plane initiates tunneling of the Cl atom through the molecular plane to turn the adsorption configuration of ClAlPc from Cl-down to an upheld Cl-up configuration, elucidating an optomechanical way of manipulating the dipole direction of polar molecules. Finally, work function measurements provide a distinct signature of the resulting upheld Cl-up configuration as it leads to a large increase in vacuum level (VL), ~ 0.4 eV higher than that of a typical flat-on Cl-up configuration driven by thermal annealing.
    • Effects of turn-structure on folding and entanglement in artificial molecular overhand knots.

      Song, Yiwei; orcid: 0000-0003-2471-6516; Schaufelberger, Fredrik; orcid: 0000-0001-5298-4310; Ashbridge, Zoe; orcid: 0000-0002-8647-712X; Pirvu, Lucian; orcid: 0000-0002-6395-0156; Vitorica-Yrezabal, Iñigo J; Leigh, David A; orcid: 0000-0002-1202-4507 (2020-12-08)
      The length and constitution of spacers linking three 2,6-pyridinedicarboxamide units in a molecular strand influence the tightness of the resulting overhand (open-trefoil) knot that the strand folds into in the presence of lanthanide(iii) ions. The use of β-hairpin forming motifs as linkers enables a metal-coordinated pseudopeptide with a knotted tertiary structure to be generated. The resulting pseudopeptide knot has one of the highest backbone-to-crossing ratios (BCR)-a measure of knot tightness (a high value corresponding to looseness)-for a synthetic molecular knot to date. Preorganization in the crossing-free turn section of the knot affects aromatic stacking interactions close to the crossing region. The metal-coordinated pseudopeptide knot is compared to overhand knots with other linkers of varying tightness and turn preorganization, and the entangled architectures characterized by NMR spectroscopy, ESI-MS, CD spectroscopy and, in one case, X-ray crystallography. The results show how it is possible to program specific conformational properties into different key regions of synthetic molecular knots, opening the way to systems where knotting can be systematically incorporated into peptide-like chains through design.
    • Can molecular flexibility control crystallization? The case of <i>para</i> substituted benzoic acids.

      Tang, Sin Kim; Davey, Roger J; orcid: 0000-0002-4690-1774; Sacchi, Pietro; orcid: 0000-0001-5066-4508; Cruz-Cabeza, Aurora J; orcid: 0000-0002-0957-4823 (2020-11-16)
      Despite the technological importance of crystallization from solutions almost nothing is known about the relationship between the kinetic process of nucleation and the molecular and crystal structures of a crystallizing solute. Nowhere is this more apparent than in our attempts to understand the behavior of increasingly large, flexible molecules developed as active components in the pharmaceutical arena. In our current contribution we develop a general protocol involving a combination of computation (conformation analysis, lattice energy), and experiment (measurement of nucleation rates), and show how significant advances can be made. We present the first systematic study aimed at quantifying the impact of molecular flexibility on nucleation kinetics. The nucleation rates of 4 <i>para</i> substituted benzoic acids are compared, two of which have substituents with flexible chains. In making this comparison, the importance of normalizing data to account for differing solubilities is highlighted. These data have allowed us to go beyond popular qualitative descriptors such 'crystallizability' or 'crystallization propensity' in favour of more precise nucleation rate data. Overall, this leads to definite conclusions as to the relative importance of solution chemistry, solid-state interactions and conformational flexibility in the crystallization of these molecules and confirms the key role of intermolecular stacking interactions in determining relative nucleation rates. In a more general sense, conclusions are drawn as to conditions under which conformational change may become rate determining during a crystallization process.
    • <i>CrystalGrower</i>: a generic computer program for Monte Carlo modelling of crystal growth.

      Hill, Adam R; orcid: 0000-0002-1877-2231; Cubillas, Pablo; Gebbie-Rayet, James T; Trueman, Mollie; de Bruyn, Nathan; Harthi, Zulaikha Al; orcid: 0000-0002-1962-7490; Pooley, Rachel J S; Attfield, Martin P; orcid: 0000-0001-6508-1751; Blatov, Vladislav A; orcid: 0000-0002-4048-7218; Proserpio, Davide M; orcid: 0000-0001-6597-9406; et al. (2020-11-18)
      A Monte Carlo crystal growth simulation tool, <i>CrystalGrower</i>, is described which is able to simultaneously model both the crystal habit and nanoscopic surface topography of any crystal structure under conditions of variable supersaturation or at equilibrium. This tool has been developed in order to permit the rapid simulation of crystal surface maps generated by scanning probe microscopies in combination with overall crystal habit. As the simulation is based upon a coarse graining at the nanoscopic level features such as crystal rounding at low supersaturation or undersaturation conditions are also faithfully reproduced. <i>CrystalGrower</i> permits the incorporation of screw dislocations with arbitrary Burgers vectors and also the investigation of internal point defects in crystals. The effect of growth modifiers can be addressed by selective poisoning of specific growth sites. The tool is designed for those interested in understanding and controlling the outcome of crystal growth through a deeper comprehension of the key controlling experimental parameters.
    • Publisher Correction: Breast cancer management pathways during the COVID-19 pandemic: outcomes from the UK 'Alert Level 4' phase of the B-MaP-C study.

      Dave, Rajiv V; orcid: 0000-0001-6827-8090; email: rajiv.dave@nhs.net; Kim, Baek; Courtney, Alona; O'Connell, Rachel; Rattay, Tim; Taxiarchi, Vicky P; Kirkham, Jamie J; Camacho, Elizabeth M; Fairbrother, Patricia; Sharma, Nisha; et al. (2021-06-23)
    • Correlating axial and equatorial ligand field effects to the single-molecule magnet performances of a family of dysprosium bis-methanediide complexes.

      Thomas-Hargreaves, Lewis R; orcid: 0000-0002-2895-6931; Giansiracusa, Marcus J; orcid: 0000-0002-2481-4063; Gregson, Matthew; Zanda, Emanuele; O'Donnell, Felix; Wooles, Ashley J; Chilton, Nicholas F; orcid: 0000-0002-8604-0171; Liddle, Stephen T; orcid: 0000-0001-9911-8778 (2021-03-02)
      Treatment of the new methanediide-methanide complex [Dy(SCS)(SCSH)(THF)] (<b>1Dy</b>, SCS = {C(PPh<sub>2</sub>S)<sub>2</sub>}<sup>2-</sup>) with alkali metal alkyls and auxillary ethers produces the bis-methanediide complexes [Dy(SCS)<sub>2</sub>][Dy(SCS)<sub>2</sub>(K(DME)<sub>2</sub>)<sub>2</sub>] (<b>2Dy</b>), [Dy(SCS)<sub>2</sub>][Na(DME)<sub>3</sub>] (<b>3Dy</b>) and [Dy(SCS)<sub>2</sub>][K(2,2,2-cryptand)] (<b>4Dy</b>). For further comparisons, the bis-methanediide complex [Dy(NCN)<sub>2</sub>][K(DB18C6)(THF)(toluene)] (<b>5Dy</b>, NCN = {C(PPh<sub>2</sub>NSiMe<sub>3</sub>)<sub>2</sub>}<sup>2-</sup>, DB18C6 = dibenzo-18-crown-6 ether) was prepared. Magnetic susceptibility experiments reveal slow relaxation of the magnetisation for <b>2Dy-5Dy</b>, with open magnetic hysteresis up to 14, 12, 15, and 12 K, respectively (∼14 Oe s<sup>-1</sup>). Fitting the alternating current magnetic susceptibility data for <b>2Dy-5Dy</b> gives energy barriers to magnetic relaxation (<i>U</i> <sub>eff</sub>) of 1069(129)/1160(21), 1015(32), 1109(70), and 757(39) K, respectively, thus <b>2Dy-4Dy</b> join a privileged group of SMMs with <i>U</i> <sub>eff</sub> values of ∼1000 K and greater with magnetic hysteresis at temperatures >10 K. These structurally similar Dy-components permit systematic correlation of the effects of axial and equatorial ligand fields on single-molecule magnet performance. For <b>2Dy-4Dy</b>, the Dy-components can be grouped into <b>2Dy-cation</b>/<b>4Dy</b> and <b>2Dy-anion</b>/<b>3Dy</b>, where the former have almost linear C[double bond, length as m-dash]Dy[double bond, length as m-dash]C units with short average Dy[double bond, length as m-dash]C distances, and the latter have more bent C[double bond, length as m-dash]Dy[double bond, length as m-dash]C units with longer average Dy[double bond, length as m-dash]C bonds. Both <i>U</i> <sub>eff</sub> and hysteresis temperature are superior for the former pair compared to the latter pair as predicted, supporting the hypothesis that a more linear axial ligand field with shorter M-L distances produces enhanced SMM properties. Comparison with <b>5Dy</b> demonstrates unusually clear-cut examples of: (i) weakening the equatorial ligand field results in enhancement of the SMM performance of a monometallic system; (ii) a positive correlation between <i>U</i> <sub>eff</sub> barrier and axial linearity in structurally comparable systems.
    • Site-to-site peptide transport on a molecular platform using a small-molecule robotic arm.

      Kassem, Salma; Lee, Alan T L; Leigh, David A; orcid: 0000-0002-1202-4507; Markevicius, Augustinas; Tetlow, Daniel J; orcid: 0000-0001-6323-3483; Toriumi, Naoyuki; orcid: 0000-0001-5963-4735 (2020-12-10)
      Peptides attached to a cysteine hydrazide 'transporter module' are transported selectively in either direction between two chemically similar sites on a molecular platform, enabled by the discovery of new operating methods for a molecular transporter that functions through ratcheting. Substrate repositioning is achieved using a small-molecule robotic arm controlled by a protonation-mediated rotary switch and attachment/release dynamic covalent chemistry. A polar solvent mixtures were found to favour <i>Z</i> to <i>E</i> isomerization of the doubly-protonated switch, transporting cargo in one direction (arbitrarily defined as 'forward') in up to 85% yield, while polar solvent mixtures were unexpectedly found to favour <i>E</i> to <i>Z</i> isomerization enabling transport in the reverse ('backward') direction in >98% yield. Transport of the substrates proceeded in a matter of hours (compared to 6 days even for simple cargoes with the original system) without the peptides at any time dissociating from the machine nor exchanging with others in the bulk. Under the new operating conditions, key intermediates of the switch are sufficiently stabilized within the macrocycle formed between switch, arm, substrate and platform that they can be identified and structurally characterized by <sup>1</sup>H NMR. The size of the peptide cargo has no significant effect on the rate or efficiency of transport in either direction. The new operating conditions allow detailed physical organic chemistry of the ratcheted transport mechanism to be uncovered, improve efficiency, and enable the transport of more complex cargoes than was previously possible.
    • Assessing Fracture Toughness and Impact Strength of PMMA Reinforced with Nano-Particles and Fibre as Advanced Denture Base Materials

      Alhotan, Abdulaziz; email: aalhotan@ksu.edu.sa; Yates, Julian; email: julian.yates@manchester.ac.uk; Zidan, Saleh; email: saleh_0072002@yahoo.co.uk; Haider, Julfikar; orcid: 0000-0001-7010-8285; email: j.haider@mmu.ac.uk; Silikas, Nikolaos; orcid: 0000-0003-4576-4584; email: nikolaos.silikas@manchester.ac.uk (MDPI, 2021-07-24)
      Statement of Problem: Polymethyl methacrylate (PMMA) denture resins commonly fracture as a result of the denture being dropped or when in use due to heavy occlusal forces. Purpose: To investigate the effects of E-glass fibre, ZrO2 and TiO2 nanoparticles at different concentrations on the fracture toughness and impact strength of PMMA denture base. Materials and Methods: To evaluate fracture toughness (dimensions: 40 × 8 × 4 mm3; n = 10/group) and impact strength (dimensions: 80 × 10 × 4 mm3; n = 12/group), 286 rectangular tested specimens were prepared and divided into four groups. Group C consisted of the PMMA specimens without any filler (control group), while the specimens in the remaining three groups varied according to the concentration of three filler materials by weight of PMMA resin: 1.5%, 3%, 5%, and 7%. Three-point bending and Charpy impact tests were conducted to measure the fracture toughness and impact strength respectively. Scanning Electron Microscope (SEM) was utilised to examine the fractured surfaces of the specimens after the fracture toughness test. One-way analysis of variance (ANOVA) followed by Tukey post-hoc tests were employed to analyse the results at a p ≤ 0.05 significance level. Results: Fracture toughness of groups with 1.5 and 3 wt.% ZrO2, 1.5 wt.% TiO2, and all E-glass fibre concentrations were significantly higher (p 0.05) than the control group. The samples reinforced with 3 wt.% ZrO2 exhibited the highest fracture toughness. Those reinforced with a 3 wt.%, 5 wt.%, and 7 wt.% of E-glass fibres had a significantly (p 0.05) higher impact strength than the specimens in the control group. The heat-cured PMMA modified with either ZrO2 or TiO2 nanoparticles did not exhibit a statistically significant difference in impact strength (p > 0.05) in comparison to the control group. Conclusions: 1.5 wt.%, 3 wt.% of ZrO2; 1.5 wt.% ratios of TiO2; and 1.5 wt.%, 3 wt.%, 5 wt.%, and 7 wt.% of E-glass fibre can effectively enhance the fracture toughness of PMMA. The inclusion of E-glass fibres does significantly improve impact strength, while ZrO2 or TiO2 nanoparticles did not.
    • Impact Response of Curved Composite Laminates: Effect of Radius and Thickness

      Harris, William; orcid: 0000-0002-5775-2428; email: william.harris-4@postgrad.manchester.ac.uk; Soutis, Constantinos; email: constantinos.soutis@manchetser.ac.uk; Atkin, Christopher (Springer Netherlands, 2020-07-25)
      Abstract: This paper presents the results of drop-weight impact testing (5 J to 30 J) on curved ±55° E-glass-epoxy laminates of varying radii and wall thickness. Three radii (75 mm, 100 mm, and 125 mm) on laminates with an effective wall thickness of 2.5 mm, and three wall thicknesses (2.5 mm, 4.1 mm, and 6.6 mm) with a radius of 100 mm were investigated. The damage pattern remained consistent, with the exception of the damage area, across the tested energies and was dominated by internal matrix cracking and multiple delaminations. However, no damage was recorded following a 5 J impact on the 2.5 mm thick laminates with 100 mm and 125 mm radii, all energy was absorbed elastically, while the laminate with a 75 mm radius of curvature developed a damage area of over 80 mm2. The thicker laminates showed a reduced overall damage area but a greater number of delaminations. The relationship between laminate thickness and delamination threshold load was found to be in line with impact testing of flat plates, varying with the laminate thickness to the 3/2 power. However, the simplified beam theory and a fracture mechanics model developed for the prediction of delamination threshold of flat plates was found to underestimate the delamination threshold load (DTL) of the curved laminates studied by about 40%. An increase in the laminate’s flexural modulus of a factor of two is required to bring the model’s predictions in line with the DTL values measured experimentally, highlighting how curvature can enhance bending stiffness and alter damage evolution. Finally, a significant finding is that the DTL of the curved plates is around 15% lower than the value measured for the whole cylindrical pipe of same specifications. Testing curved sections rather than a whole pipe could reduce effort, but further work is required to confirm this statement.
    • Thinking with ‘lexical’ features to reconceptualize the ‘grammar’ of schooling: Shifting the focus from school to society

      Courtney, Steven J.; orcid: 0000-0003-2379-7035; email: steven.courtney@manchester.ac.uk; Mann, Bryan (Springer Netherlands, 2020-08-13)
      Abstract: Achieving changes to education practices and structures is a significant issue facing reformers internationally, and researchers have confronted how such changes, and the conditions for these, might be conceptualized. These issues resonate particularly as researchers grapple with imagining a post-COVID-19 landscape where social and educational norms may change. Tyack and Tobin, in their 1994 article ‘The “Grammar” of Schooling: Why has it been so hard to change?’ argued that several features of the American education system are so persistent as to warrant being understood as the ‘grammar’ of schooling. In this article, we reconceptualize this ‘grammar’ by taking seriously Tyack and Tobin’s insistence that ‘grammar’ organises meaning. Starting here, we argue that what they took to be grammatical features are the products and not the producers of meaning. We draw on the cases of the United States and England to argue that four international discourses have performed this meaning-making work: industrialization; welfarism; neoliberalism and neoconservatism. These are the ‘grammars’ of schooling—and of society. Their discursive products, including age grading and sorting into subjects are, we suggest, ‘lexical’ features that express the grammar. We use lexical features to explain the multi-directional interplay between discourse and educational feature: the lexical may endure longer than the grammatical, changes to which may be effected and/or legitimated through appealing to a lexical feature. We conclude by outlining key implications for realizing and conceptualizing educational change, including for a post-COVID-19 landscape.
    • EFT for soft drop double differential cross section

      Pathak, Aditya; orcid: 0000-0001-8149-2817; email: aditya.pathak@manchester.ac.uk; Stewart, Iain W.; Vaidya, Varun; Zoppi, Lorenzo; orcid: 0000-0002-9157-6907 (Springer Berlin Heidelberg, 2021-04-06)
      Abstract: We develop a factorization framework to compute the double differential cross section in soft drop groomed jet mass and groomed jet radius. We describe the effective theories in the large, intermediate, and small groomed jet radius regions defined by the interplay of the jet mass and the groomed jet radius measurement. As an application we present the NLL′ results for the perturbative moments that are related to the coefficients C1 and C2 that specify the leading hadronization corrections up to three universal parameters. We compare our results with Monte Carlo simulations and a calculation using the coherent branching method.
    • Latent Class Analysis of Mental Health in Middle Childhood: Evidence for the Dual-Factor Model

      Petersen, Kimberly J.; orcid: 0000-0002-4941-6897; email: kimberly.petersen@manchester.ac.uk; Humphrey, Neil; orcid: 0000-0002-8148-9500; Qualter, Pamela; orcid: 0000-0001-6114-3820 (Springer US, 2020-07-25)
      Abstract: Mental health is complex, comprising both mental distress and well-being. This study used latent class analysis to identify common combinations of mental distress and well-being (‘mental health classes’) among schoolchildren aged 8–9 years (N = 3340). Thirteen items, measuring a range of conduct problems, emotional symptoms, and subjective well-being, were included in the analysis. Four mental health classes were identified: (1) complete mental health (n = 1895, 57%), (2) vulnerable (n = 434, 13%), (3) emotional symptoms but content (n = 606, 18%), and (4) conduct problems but content (n = 404, 12%). The classes were reliably identified across different datasets, and for males and females. Differential relations with covariates indicated that mental health classes were distinct and externally valid. The results supported the dual-factor model of mental health, suggesting that mental distress and subjective well-being are separate continua. Three of the four possible combinations of high and low distress and subjective well-being posited by the dual-factor model were found using this inductive statistical method. Importantly, our analysis also revealed two ‘symptomatic but content’ groups, differentiated by symptom domain (internalising/externalising). The covariate analyses between mental health classes and sociodemographic factors, prior academic attainment, school connectedness, and peer support, indicated that there are nuanced relations between those variables and particular constellations of mental distress and well-being. As one of the few dual-factor studies to focus on middle childhood, the current study adds important new evidence that contributes to our understanding of the complexities of mental health among schoolchildren.
    • Knowledge, attitudes and experiences of self-harm and suicide in low-income and middle-income countries: protocol for a systematic review.

      McPhillips, Rebecca; orcid: 0000-0003-4296-5970; email: rebecca.mcphillips@manchester.ac.uk; Nafees, Sadia; orcid: 0000-0003-1553-3013; Elahi, Anam; Batool, Saqba; Krishna, Murali; Krayer, Anne; orcid: 0000-0003-1503-1734; Huxley, Peter; Chaudhry, Nasim; Robinson, Catherine (2021-06-22)
      <h4>Introduction</h4>Over 800 000 people die due to suicide each year and suicide presents a huge psychological, economic and social burden for individuals, communities and countries as a whole. Low-income and middle-income countries (LMICs) are disproportionately affected by suicide. The strongest risk factor for suicide is a previous suicide attempt, and other types of self-harm have been found to be robust predictors of suicidal behaviour. An approach that brings together multiple sectors, including education, labour, business, law, politics and the media is crucial to tackling suicide and self-harm. The WHO highlights that evaluations of the knowledge and attitudes that priority groups, not only healthcare staff, have of mental health and suicidal behaviour are key to suicide prevention strategies. The aim of this systematic review is to examine the knowledge, attitudes and experiences different stakeholders in LMICs have of self-harm and suicide.<h4>Methods and analysis</h4>MEDLINE, Embase, PsycINFO, CINAHL, BNI, Social Sciences and Cochrane Library will be searched. Reviewers working independently of each other will screen search results, select studies for inclusion, extract and check extracted data, and rate the quality of the studies using the Strengthening the Reporting of Observational studies in Epidemiology and Critical Appraisals Skills Programme checklists. In anticipation of heterogeneity, a narrative synthesis of quantitative studies will be provided and metaethnography will be used to synthesise qualitative studies.<h4>Ethics and dissemination</h4>Ethical approval is not required. A report will be provided for the funding body, and the systematic review will be submitted for publication in a high-impact, peer-reviewed, open access journal. Results will also be disseminated at conferences, seminars, congresses and symposia, and to relevant stakeholders.<h4>Prospero registration number</h4>CRD42019135323.