Scalable production of large quantities of defect-free few-layer graphene by shear exfoliation in liquids

To progress from the laboratory to commercial applications, it will be necessary to develop industrially scalable methods to produce large quantities of defect-free graphene. Here we show that high-shear mixing of graphite in suitable stabilizing liquids results in large-scale exfoliation to give dispersions of graphene nanosheets. X-ray photoelectron spectroscopy and Raman spectroscopy show the exfoliated flakes to be unoxidized and free of basal-plane defects. We have developed a simple model that shows exfoliation to occur once the local shear rate exceeds 10(4) s(-1). By fully characterizing the scaling behaviour of the graphene production rate, we show that exfoliation can be achieved in liquid volumes from hundreds of millilitres up to hundreds of litres and beyond. The graphene produced by this method performs well in applications from composites to conductive coatings. This method can be applied to exfoliate BN, MoS2 and a range of other layered crystals

Research priorities for children's cancer : a James Lind Alliance Priority Setting Partnership in the UK

OBJECTIVES: To engage children who have experienced cancer, childhood cancer survivors, their families and professionals to systematically identify and prioritise research questions about childhood cancer to inform the future research agenda. DESIGN: James Lind Alliance Priority Setting Partnership. SETTING: UK health service and community. METHODS: A steering group oversaw the initiative. Potential research questions were collected in an online survey, then checked to ensure they were unanswered. Shortlisting via a second online survey identified the highest priority questions. A parallel process with children was undertaken. A final consensus workshop was held to determine the Top 10 priorities. PARTICIPANTS: Children and survivors of childhood cancer, diagnosed before age 16, their families, friends and professionals who work with this population. RESULTS: Four hundred and eighty-eight people submitted 1299 potential questions. These were refined into 108 unique questions; 4 were already answered and 3 were under active study, therefore, removed. Three hundred and twenty-seven respondents completed the shortlisting survey. Seventy-one children submitted questions in the children's surveys, eight children attended a workshop to prioritise these questions. The Top 5 questions from children were taken to the final workshop where 23 questions in total were discussed by 25 participants (young adults, carers and professionals). The top priority was 'can we find effective and kinder (less burdensome, more tolerable, with fewer short and long-term effects) treatments for children with cancer, including relapsed cancer?' CONCLUSIONS: We have identified research priorities for children's cancer from the perspectives of children, survivors, their families and the professionals who care for them. Questions reflect the breadth of the cancer experience, including diagnosis, relapse, hospital experience, support during/after treatment and the long-term impact of cancer. These should inform funding of future research as they are the questions that matter most to the people who could benefit from research

The impact of viral mutations on recognition by SARS-CoV-2 specific T cells.

We identify amino acid variants within dominant SARS-CoV-2 T cell epitopes by interrogating global sequence data. Several variants within nucleocapsid and ORF3a epitopes have arisen independently in multiple lineages and result in loss of recognition by epitope-specific T cells assessed by IFN-γ and cytotoxic killing assays. Complete loss of T cell responsiveness was seen due to Q213K in the A∗01:01-restricted CD8+ ORF3a epitope FTSDYYQLY207-215; due to P13L, P13S, and P13T in the B∗27:05-restricted CD8+ nucleocapsid epitope QRNAPRITF9-17; and due to T362I and P365S in the A∗03:01/A∗11:01-restricted CD8+ nucleocapsid epitope KTFPPTEPK361-369. CD8+ T cell lines unable to recognize variant epitopes have diverse T cell receptor repertoires. These data demonstrate the potential for T cell evasion and highlight the need for ongoing surveillance for variants capable of escaping T cell as well as humoral immunity.This work is supported by the UK Medical Research Council (MRC); Chinese Academy of Medical Sciences(CAMS) Innovation Fund for Medical Sciences (CIFMS), China; National Institute for Health Research (NIHR)Oxford Biomedical Research Centre, and UK Researchand Innovation (UKRI)/NIHR through the UK Coro-navirus Immunology Consortium (UK-CIC). Sequencing of SARS-CoV-2 samples and collation of data wasundertaken by the COG-UK CONSORTIUM. COG-UK is supported by funding from the Medical ResearchCouncil (MRC) part of UK Research & Innovation (UKRI),the National Institute of Health Research (NIHR),and Genome Research Limited, operating as the Wellcome Sanger Institute. T.I.d.S. is supported by a Well-come Trust Intermediate Clinical Fellowship (110058/Z/15/Z). L.T. is supported by the Wellcome Trust(grant number 205228/Z/16/Z) and by theUniversity of Liverpool Centre for Excellence in Infectious DiseaseResearch (CEIDR). S.D. is funded by an NIHR GlobalResearch Professorship (NIHR300791). L.T. and S.C.M.are also supported by the U.S. Food and Drug Administration Medical Countermeasures Initiative contract75F40120C00085 and the National Institute for Health Research Health Protection Research Unit (HPRU) inEmerging and Zoonotic Infections (NIHR200907) at University of Liverpool inpartnership with Public HealthEngland (PHE), in collaboration with Liverpool School of Tropical Medicine and the University of Oxford.L.T. is based at the University of Liverpool. M.D.P. is funded by the NIHR Sheffield Biomedical ResearchCentre (BRC – IS-BRC-1215-20017). ISARIC4C is supported by the MRC (grant no MC_PC_19059). J.C.K.is a Wellcome Investigator (WT204969/Z/16/Z) and supported by NIHR Oxford Biomedical Research Centreand CIFMS. The views expressed are those of the authors and not necessarily those of the NIHR or MRC

Low temperature graphene growth

We demonstrate the growth of graphene films on nickel substrates by chemical vapour deposition using acetylene at temperatures as low as 750 degrees celsius, opening a viable route for its scalable production. Raman spectroscopy was used to confirm defect-free mono and multilayer graphene at and above this temperature, and of defective graphene at lower temperatures. Atomic force microscopy and scanning electron microscopy performed directly on the films give an indication of graphene flake size, morphology and also the topography on substrate. An unexpected dependence of graphene thickness on precursor dwell time is reported. This together with low temperature growth suggests deficiencies in existing growth models and hints at a more complicated growth mechanism

Electrochemical ascorbic acid sensor based on DMF-exfoliated graphene

This paper describes the electron transfer properties of graphene nano-sheets (GNSs) immobilised on pyrolysed photoresist film (PPF) electrodes. The former are produced by the dispersion and exfoliation of graphite in dimethylformamide, and they are characterised using transmission electron microscopy, scanning electron microscopy and Raman spectroscopy. Cyclic voltammetry and electrochemical impedance spectroscopy are used to quantify the effect of the GNSs on electrochemical surface area and on electron transfer kinetics. Compelling evidence is reported in relation to the importance of edge-plane sites and defects in the promotion of electron transfer at carbon nanostructures. A novel ascorbic acid (vitamin C) sensor is presented based on the PPF/GNS system, which is effective in the range 0.4 to 6.0 mM, with a 0.12 mM detection limit. The selectivity of the sensor is demonstrated using a commercially available vitamin C supplement. This is the first report of the electrochemical properties of graphene nano-sheets produced using liquid-phase exfoliation, and it will serve as an important benchmark in the development of inexpensive graphene-based electrodes with high surface area and electro-catalytic activity

Simultaneous electrochemical determination of dopamine and paracetamol based on thin pyrolytic carbon films

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Electroanalytical Sensing Properties of Pristine and Functionalized Multilayer Graphene

This paper describes the heterogeneous electron transfer (ET) properties of high-quality multilayer graphene (MLG) films grown using chemical vapor deposition (CVD) on nickel and transferred to insulating poly­(ethylene terephthalate) (PET) sheets. An oxygen plasma treatment is used to enhance the ET properties of the films by generating oxygenated functionalities and edge-plane sites and defects. Scanning electron microscopy (SEM), Raman, and X-ray photoelectron spectroscopy (XPS) along with voltammetry of the standard redox probes [Ru­(NH₃)₆]^3+/2+, [Fe­(CN)₆]^3–/4–, and Fe^3+/2+ are used to demonstrate this effect. The biologically relevant molecules dopamine, NADH, ascorbic acid, and uric acid are employed to show the improved sensing characteristics of the treated films. Control experiments involving commercially available edge-plane and basal-plane pyrolytic graphite (EPPG and BPPG) electrodes help to explain the different responses observed for each probe, and it is shown that, in certain cases, treated MLG provides a viable alternative to EPPG, hitherto considered to be the “best-case scenario” in carbon electrochemistry. This is the first comprehensive study of the electroanalytical properties of pristine and functionalized CVD-grown MLG, and it will serve as an important benchmark in the clarification of ET behavior at graphene surfaces, with a view to the development of novel electrochemical sensors

Electroanalytical Sensing Properties of Pristine and Functionalized Multilayer Graphene

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