• H,

      Cabello-Lobato, Maria Jose; Schmidt, Christine K; orcid: 0000-0002-8363-7933; email: christine.schmidt@manchester.ac.uk; Cliff, Matthew J; orcid: 0000-0002-7482-0234; email: matthew.cliff@manchester.ac.uk (2021-06-25)
      DNA double-strand breaks (DSBs) represent the most cytotoxic DNA lesions, as-if mis- or unrepaired-they can cause cell death or lead to genome instability, which in turn can cause cancer. DSBs are repaired by two major pathways termed homologous recombination and non-homologous end-joining (NHEJ). NHEJ is responsible for repairing the vast majority of DSBs arising in human cells. Defects in NHEJ factors are also associated with microcephaly, primordial dwarfism and immune deficiencies. One of the key proteins important for mediating NHEJ is XRCC4. XRCC4 is a dimer, with the dimer interface mediated by an extended coiled-coil. The N-terminal head domain forms a mixed alpha-beta globular structure. Numerous factors interact with the C-terminus of the coiled-coil domain, which is also associated with significant self-association between XRCC4 dimers. A range of construct lengths of human XRCC4 were expressed and purified, and the 1-164 variant had the best NMR properties, as judged by consistent linewidths, and chemical shift dispersion. In this work we report the H,  N and C backbone resonance assignments of human XRCC4 in the solution form of the 1-164 construct. Assignments were obtained by heteronuclear multidimensional NMR spectroscopy. In total, 156 of 161 assignable residues of XRCC4 were assigned to resonances in the TROSY spectrum, with an additional 11 resonances assigned to His-Tag residues. Prediction of solution secondary structure from a chemical shift analysis using the TALOS + webserver is in good agreement with the published X-ray crystal structures of this protein.
    • Halogens in Eclogite Facies Minerals from the Western Gneiss Region, Norway

      Hughes; orcid: 0000-0002-4363-8675; email: lewis.hughes@manchester.ac.uk; Cuthbert; orcid: 0000-0002-1029-6357; email: simon.cuthbert@agh.edu.pl; Quas-Cohen; email: alexandra.quas-cohen@postgrad.manchester.ac.uk; Ruzié-Hamilton; orcid: 0000-0002-2802-8123; email: lorraine.ruzie@manchester.ac.uk; Pawley; orcid: 0000-0002-3022-3235; email: alison.pawley@manchester.ac.uk; Droop; email: giles.droop@gmail.com; Lyon; email: Ian.Lyon@manchester.ac.uk; Tartèse; email: romain.tartese@manchester.ac.uk; Burgess; orcid: 0000-0001-7674-8718; email: ray.burgess@manchester.ac.uk (MDPI, 2021-07-14)
      Ultra-high-pressure (UHP) eclogites and ultramafites and associated fluid inclusions from the Western Gneiss Region, Norwegian Caledonides, have been analysed for F, Cl, Br and I using electron-probe micro-analysis, time-of-flight secondary ion mass spectrometry and neutron-irradiated noble gas mass spectrometry. Textures of multi-phase and fluid inclusions in the cores of silicate grains indicate formation during growth of the host crystal at UHP. Halogens are predominantly hosted by fluid inclusions with a minor component from mineral inclusions such as biotite, phengite, amphibole and apatite. The reconstructed fluid composition contains between 11.3 and 12.1 wt% Cl, 870 and 8900 ppm Br and 6 and 169 ppm I. F/Cl ratios indicate efficient fractionation of F from Cl by hydrous mineral crystallisation. Heavy halogen ratios are higher than modern seawater by up to two orders of magnitude for Br/Cl and up to three orders of magnitude for I/Cl. No correlation exists between Cl and Br or I, while Br and I show good correlation, suggesting that Cl behaved differently to Br and I during subduction. Evolution to higher Br/Cl ratios is similar to trends defined by eclogitic hydration reactions and seawater evaporation, indicating preferential removal of Cl from the fluid during UHP metamorphism. This study, by analogy, offers a field model for an alternative source (continental crust) and mechanism (metasomatism by partial melts or supercritical fluids) by which halogens may be transferred to and stored in the sub-continental lithospheric mantle during transient subduction of a continental margin.
    • Halokinetic modulation of sedimentary thickness and architecture: A numerical modelling approach

      Cumberpatch, Zoë A.; orcid: 0000-0001-8253-8418; email: zoe.cumberpatch@manchester.ac.uk; Finch, Emma; Kane, Ian A.; Pichel, Leonardo M.; Jackson, Christopher A.‐L.; Kilhams, Ben A.; Hodgson, David M.; Huuse, Mads (2021-07-03)
      Abstract: Subsurface salt flow can deform overlying strata and influence contemporaneous sedimentary systems. Studying salt‐sediment interactions is challenging in the subsurface due to poor imaging adjacent to salt, and in the field due to the dissolution of halite. Discrete Element Modelling provides an efficient and inexpensive tool to model stratigraphy and deformation around salt structures, which is advantageous over other modelling techniques as it realistically recreates brittle processes such as faulting. Six 2D experiments were run representing 4.6 Myr to determine the effect of salt growth on syn‐kinematic stratigraphy. Halokinetic deformation of stratigraphic architecture was assessed by varying sediment input rates through time. Results show the realistic formation and evolution of salt‐related faults which define a zone of halokinetic influence ca. 3 times the width of the initial diapir. Outside of this, early diapiric and syn‐kinematic stratigraphy are undeformed. Within this zone, syn‐kinematic strata are initially isolated into primary salt withdrawal basins, onlapping and thinning towards the salt‐cored high. In most models, syn‐kinematic strata eventually thin across and cover the diapir roof. Thinning rates are up to six times greater within 350 m of the diapir, compared to further afield, and typically decrease upwards (with time) and laterally (with distance) from the diapir. Outputs are compared to a subsurface example from the Pierce field, UK North Sea, which highlights the importance of considering local fluctuations in diapir rise rate. These can create stratigraphic architectures that may erroneously be interpreted to represent increases/decreases in sedimentation rate. Exposed examples, such as the Bakio diapir, northern Spain, can be used to make inferences of the expected depositional facies, below model resolution. Our models aid the prediction of sedimentary unit thickness and thinning rates and can be used to test interpretations arising from incomplete or low‐resolution subsurface and outcrop data when building geological models for subsurface energy.
    • Harnessing repeated measurements of predictor variables for clinical risk prediction: a review of existing methods

      Bull, Lucy M.; orcid: 0000-0002-3926-3030; email: lucy.bull@manchester.ac.uk; Lunt, Mark; Martin, Glen P.; Hyrich, Kimme; Sergeant, Jamie C. (BioMed Central, 2020-07-09)
      Abstract: Background: Clinical prediction models (CPMs) predict the risk of health outcomes for individual patients. The majority of existing CPMs only harness cross-sectional patient information. Incorporating repeated measurements, such as those stored in electronic health records, into CPMs may provide an opportunity to enhance their performance. However, the number and complexity of methodological approaches available could make it difficult for researchers to explore this opportunity. Our objective was to review the literature and summarise existing approaches for harnessing repeated measurements of predictor variables in CPMs, primarily to make this field more accessible for applied researchers. Methods: MEDLINE, Embase and Web of Science were searched for articles reporting the development of a multivariable CPM for individual-level prediction of future binary or time-to-event outcomes and modelling repeated measurements of at least one predictor. Information was extracted on the following: the methodology used, its specific aim, reported advantages and limitations, and software available to apply the method. Results: The search revealed 217 relevant articles. Seven methodological frameworks were identified: time-dependent covariate modelling, generalised estimating equations, landmark analysis, two-stage modelling, joint-modelling, trajectory classification and machine learning. Each of these frameworks satisfies at least one of three aims: to better represent the predictor-outcome relationship over time, to infer a covariate value at a pre-specified time and to account for the effect of covariate change. Conclusions: The applicability of identified methods depends on the motivation for including longitudinal information and the method’s compatibility with the clinical context and available patient data, for both model development and risk estimation in practice.
    • Haunting, ruination and encounter in the ordinary Anthropocene: storying the return Florida’s wild flamingos

      Fredriksen, Aurora; orcid: 0000-0003-4287-3443; email: aurora.fredriksen@manchester.ac.uk (SAGE Publications, 2021-03-21)
      In the spring of 2006 wild flamingos returned to Florida, though not to the places their kind had inhabited 100 years and more ago at the southern edge of the Everglades and the Florida Keys. Instead this group of flamingos alighted 80 miles northward in Palm Beach County’s Stormwater Treatment Area 2 (STA-2), a human-made facility for filtering anthropogenic pollutants from storm runoff. This paper takes the return of wild flamingos to Florida as a case for thinking through haunting, ruination and encounters in what I call ‘the ordinary Anthropocene’: the ongoing, everyday more-than-human relationships, actions and less-than-planetary assemblages through which the Anthropocene is sensed and lived. After setting out a case for thinking with haunting, ruination and encounter as a way of making sense in the ordinary Anthropocene, I trace three interwoven narrative threads that unspool from the encounter with the STA-2 flamingos: First, I trace the transfiguration of living wild flamingos into idealised symbols of tropical dreamworlds over the 20th century. This leads me sideways to the present-absence of flamingos in the mid-century writings of Rachel Carson and through her backwards to John J. Audubon and the genocidal ruinations of the 19th century as they flicker in the margins of his ornithological writings. I end by returning to the present, to the encounter with STA-2 flamingos in the ongoing moment of living with others in the late capitalist ecologies of south Florida. The conclusion considers what might be taken forward, into the uncertain future, from this telling.
    • ‘He didn’t really talk about it’: the (re)construction and transmission of a Free French past

      Millington, Chris; Millington, Richard; orcid: 0000-0002-1324-9521 (Informa UK Limited, 2021-12-21)
    • Health and healthcare in North Korea: a retrospective study among defectors

      Lee, Hayoung; Robinson, Courtland; Kim, Jaeshin; McKee, Martin; Cha, Jiho; orcid: 0000-0003-1212-5671; email: jiho.cha@manchester.ac.uk (BioMed Central, 2020-06-29)
      Abstract: Background: To gain insights into the socio-economic and political determinants of ill health and access to healthcare in North Korea. Methods: A retrospective survey using respondent-driven sampling conducted in 2014–15 among 383 North Korean refugees newly resettling in South Korea, asking about experiences of illness and utilization of healthcare while in North Korea, analyzed according to measures of political, economic and human rights indicators. Results: Although the Public Health Act claims that North Korea provides the comprehensive free care system, respondents reported high levels of unmet need and, among those obtaining care, widespread informal expenditure. Of the respondents, 55.1% (95%CI, 47.7–63.7%) had received healthcare for the most recent illness episode. High informal costs (53.8%, 95%CI, 45.1–60.8%) and a lack of medicines (39.5%, 95%CI, 33.3–47.1%) were reported as major healthcare barriers resulting in extensive self-medication with narcotic analgesics (53.7%, 95%CI, 45.7–61.2%). In multivariate logistic regressions, party membership was associated with better access to healthcare (Adjusted OR (AOR) = 2.34, 95%CI, 1.31–4.18), but household income (AOR = 0.40, 95%CI 0.21–0.78) and informal market activity (AOR = 0.29, 95%CIs 0.15–0.50) with reduced access. Respondents who could not enjoy political and economic rights were substantially more likely to report illness and extremely reduced access to care, even with life-threatening conditions. Conclusions: There are large disparities in health and access to healthcare in North Korea, associated with political and economic inequalities. The scope to use these findings to bring about change is limited but they can inform international agencies and humanitarian organizations working in this unique setting.
    • Health impacts of daily weather fluctuations: Empirical evidence from COVID-19 in U.S. counties.

      Emediegwu, Lotanna E; email: lotanna.emediegwu@manchester.ac.uk (2021-04-24)
      The emergence of the novel coronavirus has necessitated immense research efforts to understand how several non-environmental and environmental factors affect transmission. With the United States leading the path in terms of case incidence, it is important to investigate how weather variables influence the spread of the disease in the country. This paper assembles a detailed and comprehensive dataset comprising COVID-19 cases and climatological variables for all counties in the continental U.S. and uses a developed econometric approach to estimate the causal effect of certain weather factors on the growth rate of infection. The results indicate a non-linear and significant negative relationship between the individual weather measures and the growth rate of COVID-19 in the U.S. Specifically, the paper finds that a 1 °C rise in daily temperature will reduce daily covid growth rate in the U.S. by approximately 6 percent in the following week, while a marginal increase in relative humidity reduces the same outcome by 1 percent over a similar period. In comparison, a 1 m/s increase in daily wind speed will bring about an 8 percent drop in daily growth rate of COVID-19 in the country. These results differ by location and are robust to several sensitivity checks, so large deviations are unexpected. [Abstract copyright: Copyright © 2021 The Author(s). Published by Elsevier Ltd.. All rights reserved.]
    • Health inequalities as a foundation for embodying knowledge within public health teaching: a qualitative study

      Mabhala, Mzwandile A.; University of Chester (BioMed Central, 2013-06-28)
      Introduction: Recent UK health policies identified nurses as key contributors to the social justice agenda of reducing health inequalities, on the assumption that all nurses understand and wish to contribute to public health. Following this policy shift, public health content within pre-registration nursing curricula increased. However, public health nurse educators (PHNEs) had various backgrounds, and some had limited formal public health training, or involvement in or understanding of policy required to contribute effectively to it. Their knowledge of this subject, their understanding and interpretation of how it could be taught, was not fully understood. Methodology This research aimed to understand how public health nurse educators’ professional knowledge could be conceptualised and to develop a substantive theory of their knowledge of teaching public health, using a qualitative data analysis approach. Qualitative in-depth semi-structured interviews (n=26) were conducted with eleven university-based PHNEs. Results Integrating public health into all aspects of life was seen as central to the knowing and teaching of public health; this was conceptualised as ‘embodying knowledge’. Participants identified the meaning of embodying knowledge for teaching public health as: (a) possessing a wider vision of health; (b) reflecting and learning from experience; and (c) engaging in appropriate pedagogical practices. Conclusion The concept of public health can mean different things to different people. The variations of meaning ascribed to public health reflect the various backgrounds from which the public health workforce is drawn. The analysis indicates that PHNEs are embodying knowledge for teaching through critical pedagogy, which involves them engaging in transformative, interpretive and integrative processes to refashion public health concepts; this requires PHNEs who possess a vision of what to teach, know how to teach, and are able to learn from experience. Their vision of public health is influenced by social justice principles in that health inequalities, socioeconomic determinants of health, epidemiology, and policy and politics are seen as essential areas of the public health curriculum. They believe in forms of teaching that achieve social transformation at individual, behavioural and societal levels, while also enabling learners to recognise their capacity to effect change.
    • Health technology assessment for gene therapies in haemophilia

      O'Hara, Jamie; Neumann, Peter J. (Wiley, 2022-01-25)
    • Health technology assessment for gene therapies in haemophilia

      O'Hara, Jamie; Neumann, Peter J. (Wiley, 2022-01-25)
    • Health-related quality of life, direct medical and societal costs among children with moderate or severe haemophilia in Europe: multivariable models of the CHESS-PAEDs study.

      Rodriguez-Santana, Idaira; orcid: 0000-0003-2022-3239; DasMahapatra, Pronabesh; Burke, Tom; Hakimi, Zalmai; Bartelt-Hofer, José; Nazir, Jameel; O'Hara, Jamie (2022-04-04)
      <h4>Background</h4>Haemophilia bears substantial humanistic and economic burden on children and their caregivers. Characterising the differential impact of severe versus moderate paediatric haemophilia is important for clinical and health policy decisions. We analysed health-related quality of life (HRQoL), annual direct medical (excluding factor treatment costs), non-medical and societal costs among children and adolescents with moderate and severe haemophilia A or B without inhibitors from the European CHESS-PAEDs study. Information was reported by physicians and caregivers; patients aged ≥ 8 years self-reported their HRQoL. Descriptive statistics summarised demographic and clinical characteristics, costs, and HRQoL scores (EQ-5D-Y). Regression models estimated differences in HRQoL and costs for moderate versus severe haemophilia adjusting for age, body mass index z-score, country, number of comorbidities, and weight-adjusted annual clotting factor consumption.<h4>Results</h4>The analytic sample comprised 794 patients with a mean age of 10.5 years; most had haemophilia A (79%) and 58% had severe haemophilia. Mean predicted direct medical costs in moderate patients were two-thirds of the predicted costs for severe disease (€3065 vs. €2047; p < 0.001; N = 794), while societal costs were more than half of the predicted costs for children with severe haemophilia (€6950 vs. €3666; p < 0.001; N = 220). Mean predicted HRQoL scores were 0.74 and 0.69 for moderate and severe disease, respectively (p < 0.05; N = 185).<h4>Conclusion</h4>Children with haemophilia and their caregivers displayed a significant economic and humanistic burden. While severe patients showed the highest direct medical and societal costs, and worse HRQoL, the burden of moderate haemophilia on its own was substantial and far from negligible.
    • Heritability of haemodynamics in the ascending aorta

      McGurk, Kathryn A.; email: K.McGurk@imperial.ac.uk; Owen, Benjamin; Watson, William D.; Nethononda, Richard M.; Cordell, Heather J.; Farrall, Martin; Rider, Oliver J.; Watkins, Hugh; Revell, Alistair; Keavney, Bernard D.; email: Bernard.Keavney@manchester.ac.uk (Nature Publishing Group UK, 2020-09-01)
      Abstract: Blood flow in the vasculature can be characterised by dimensionless numbers commonly used to define the level of instabilities in the flow, for example the Reynolds number, Re. Haemodynamics play a key role in cardiovascular disease (CVD) progression. Genetic studies have identified mechanosensitive genes with causal roles in CVD. Given that CVD is highly heritable and abnormal blood flow may increase risk, we investigated the heritability of fluid metrics in the ascending aorta calculated using patient-specific data from cardiac magnetic resonance (CMR) imaging. 341 participants from 108 British Caucasian families were phenotyped by CMR and genotyped for 557,124 SNPs. Flow metrics were derived from the CMR images to provide some local information about blood flow in the ascending aorta, based on maximum values at systole at a single location, denoted max, and a ‘peak mean’ value averaged over the area of the cross section, denoted pm. Heritability was estimated using pedigree-based (QTDT) and SNP-based (GCTA-GREML) methods. Estimates of Reynolds number based on spatially averaged local flow during systole showed substantial heritability (hPed2=41%[P=0.001], hSNP2=39%[P=0.002]), while the estimated heritability for Reynolds number calculated using the absolute local maximum velocity was not statistically significant (12–13%; P>0.05). Heritability estimates of the geometric quantities alone; e.g. aortic diameter (hPed2=29%[P=0.009], hSNP2=30%[P=0.010]), were also substantially heritable, as described previously. These findings indicate the potential for the discovery of genetic factors influencing haemodynamic traits in large-scale genotyped and phenotyped cohorts where local spatial averaging is used, rather than instantaneous values. Future Mendelian randomisation studies of aortic haemodynamic estimates, which are swift to derive in a clinical setting, will allow for the investigation of causality of abnormal blood flow in CVD.
    • Hermetia illucens (L.) (Diptera: Stratiomyidae) Odorant Binding Proteins and Their Interactions with Selected Volatile Organic Compounds: An in Silico Approach

      Scieuzo, Carmen; email: carmen.scieuzo@unibas.it; Nardiello, Marisa; email: nardiellomarisa@gmail.com; Farina, Donatella; email: donatella.farina.92@gmail.com; Scala, Andrea; email: andreascala@inwind.it; Cammack, Jonathan A.; email: jcammack_07@tamu.edu; Tomberlin, Jeffery K.; orcid: 0000-0002-0560-4466; email: jktomberlin@tamu.edu; Vogel, Heiko; orcid: 0000-0001-9821-7731; email: hvogel@ice.mpg.de; Salvia, Rosanna; orcid: 0000-0002-6661-7164; email: r.salvia@unibas.it; Persaud, Krishna; email: krishna.persaud@manchester.ac.uk; Falabella, Patrizia; orcid: 0000-0003-0304-6867; email: patrizia.falabella@unibas.it (MDPI, 2021-09-11)
      The black soldier fly (BSF), Hermetia illucens (Diptera: Stratiomyidae), has considerable global interest due to its outstanding capacity in bioconverting organic waste to insect biomass, which can be used for livestock, poultry, and aquaculture feed. Mass production of this insect in colonies requires the development of methods concentrating oviposition in specific collection devices, while the mass production of larvae and disposing of waste may require substrates that are more palatable and more attractive to the insects. In insects, chemoreception plays an essential role throughout their life cycle, responding to an array of chemical, biological and environmental signals to locate and select food, mates, oviposition sites and avoid predators. To interpret these signals, insects use an arsenal of molecular components, including small proteins called odorant binding proteins (OBPs). Next generation sequencing was used to identify genes involved in chemoreception during the larval and adult stage of BSF, with particular attention to OBPs. The analysis of the de novo adult and larval transcriptome led to the identification of 27 and 31 OBPs for adults and larvae, respectively. Among these OBPs, 15 were common in larval and adult transcriptomes and the tertiary structures of 8 selected OBPs were modelled. In silico docking of ligands confirms the potential interaction with VOCs of interest. Starting from the information about the growth performance of H. illucens on different organic substrates from the agri-food sector, the present work demonstrates a possible correlation between a pool of selected VOCs, emitted by those substrates that are attractive for H. illucens females when searching for oviposition sites, as well as phagostimulants for larvae. The binding affinities between OBPs and selected ligands calculated by in silico modelling may indicate a correlation among OBPs, VOCs and behavioural preferences that will be the basis for further analysis.
    • Heuristic assessment of psychological interventions in schools (HAPI Schools)

      Platt, Ian A.; orcid: 0000-0003-2497-6713; Kannangara, Chathurika; orcid: 0000-0001-6955-8158; Carson, Jerome; orcid: 0000-0002-7596-116X; Tytherleigh, Michelle; orcid: 0000-0003-2498-8175 (Wiley, 2021-05-02)
    • Heuristic assessment of psychological interventions in schools (HAPI Schools)

      Platt, Ian A.; orcid: 0000-0003-2497-6713; email: iap1hss@bolton.ac.uk; Kannangara, Chathurika; orcid: 0000-0001-6955-8158; Carson, Jerome; orcid: 0000-0002-7596-116X; Tytherleigh, Michelle; orcid: 0000-0003-2498-8175 (2021-05-02)
      Abstract: Children spend more time in school than in any other formal setting and, with mental illness in children on the rise, there is more pressure on schools to intervene in student mental health than ever before. In the current study, two phases of semistructured interviews were conducted with school leaders and special educational needs coordinators (Phase 1, N = 23; Phase 2, N = 11), to investigate first‐hand experiences in dealing with student mental illness. Thematic analysis, drawing on Grounded Theory, was used to identify themes. The results identified deprivation as one of the main causes of mental ill‐health in students, with insufficient budgets, inappropriate mental health services, and overly long waiting times as barriers to intervention. Difficulties in identifying appropriate mental health interventions to use in school were also reported. The authors propose a simple four‐point heuristic, for assessing the quality of school‐based mental health interventions to be used by school staff, so that educators can more readily identify appropriate mental health support for their students.
    • Heuristic assessment of psychological interventions in schools (HAPI Schools)

      Platt, Ian A.; orcid: 0000-0003-2497-6713; Kannangara, Chathurika; orcid: 0000-0001-6955-8158; Carson, Jerome; orcid: 0000-0002-7596-116X; Tytherleigh, Michelle; orcid: 0000-0003-2498-8175 (Wiley, 2021-05-02)
    • Hidden dynamics for piecewise smooth maps

      Glendinning, Paul; orcid: 0000-0003-1544-9161; email: p.a.glendinning@manchester.ac.uk; Jeffrey, Mike R; orcid: 0000-0002-3325-7211; email: mike.jeffrey@bristol.ac.uk (IOP Publishing, 2021-05-07)
      Abstract: We develop a hidden dynamics formulation of regularisation for piecewise smooth maps. This involves blowing up the discontinuity into an interval, but in contrast to piecewise smooth flows every preimage of the discontinuity needs to be blown up as well. This results in a construction similar to classic approaches to the Denjoy counterexample.
    • Hidden dynamics for piecewise smooth maps

      Glendinning, Paul; orcid: 0000-0003-1544-9161; email: p.a.glendinning@manchester.ac.uk; Jeffrey, Mike R; orcid: 0000-0002-3325-7211; email: mike.jeffrey@bristol.ac.uk (IOP Publishing, 2021-05-07)
      Abstract: We develop a hidden dynamics formulation of regularisation for piecewise smooth maps. This involves blowing up the discontinuity into an interval, but in contrast to piecewise smooth flows every preimage of the discontinuity needs to be blown up as well. This results in a construction similar to classic approaches to the Denjoy counterexample.
    • Hierarchical porous poly( l -lactic acid)/SiO 2 nanoparticles fibrous membranes for oil/water separation

      Lu, Zihan; orcid: 0000-0001-9835-4015; Zia, Qasim; Meng, Jinmin; Liu, Ting; Song, Jun; Li, Jiashen; email: jiashen.li@manchester.ac.uk (Springer US, 2020-09-02)
      Abstract: A two-step strategy has been developed to introduce silica nanoparticles into highly porous poly(l-lactic acid) (PLLA) nanofibers. Silica nanoparticles (SiNPs) were firstly synthesized and then modified to be hydrophobic. After PLLA/SiNPs composite fibrous membranes were electrospun and collected, they were re-crystallized by acetone at room temperature for a few minutes. With the re-arrangement of PLLA chains, the nano-/micro-electrospun fibres were transformed from non-porous ones to be porous ones with high surface area. Consequently, SiNPs that were completely covered by PLLA before acetone treatment showed up at the fibre surface. Higher PLLA crystallization also enhanced the Young’s modulus and tensile strength (420 and 8.47 MPa) of the composite membrane. However, incorporation of SiNPs into porous PLLA membranes reduced their modulus and tensile strength (280.66 and 5.92 MPa), but an increase in strain to fracture (80.82%) was observed. Scanning electron microscopy (SEM), focused ion beam SEM, transmission electron microscopy, Fourier transform infrared spectroscopy and X-ray diffraction were applied to confirm the presence of SiNP in PLLA fibres. The presence of SiNPs inside and outside fibres enhances the hydrophobicity of PLLA/SiNPs nano-fibrous membrane as the water contact angle is greater than 150°. The oil absorption of these porous composite membranes was also tested using four different oils, which can reach the highest absorption capacity when the weight ratio of PLLA and SiNPs is 1:1. The flux of prepared membranes was investigated, and results indicated that SiNPs-loaded membrane effectively enhanced the flux (5200 Lm−2 h−1).