Med Peds Poster - 2019

Med Peds Poster - 2019https://scholarlycommons.libraryinfo.bhs.org/research_education/1003/thumbnail.jp

Functionalised hexagonal-domain graphene for position-sensitive photodetectors

LetterThis is the author accepted manuscript. The final version is available from IOP Publishing via the DOI in this record.Graphene's unique photoresponse has been largely used in a multitude of optoelectronics applications ranging from broadband photodetectors to wave-guide modulators. In this work we extend the range of applications to position-sensitive photodetectors (PSDs) using FeCl3-intercalated hexagonal domains of graphene grown by atmospheric pressure chemical vapour deposition (APCVD). The FeCl3-based chemical functionalisation of APCVD graphene crystals is affected by the presence of wrinkles and results in a non-uniform doping of the graphene layers. This doping profile creates multiple p–p+ photoactive junctions which show a linear and bipolar photoresponse with respect to the position of a focused light spot, which is ideal for the realization of a PSD. Our study paves the way towards the fabrication of flexible and transparent PSDs that could be embedded in smart textile and wearable electronics.S Russo and M F Craciun acknowledge financial support from EPSRC (Grant no. EP/J000396/1, EP/K017160/1, EP/K010050/1, EPG036101/1, EP/M001024/1, EPM002438/1), from Royal Society international Exchanges Scheme 2016/R1, from European Commission (FP7-ICT-2013-613024-GRASP) and from the Leverhulme Trust (grant title 'Quantum Drums' and 'Room temperature quantum electronics'). I Amit received funding from the People Programme (Marie Curie Actions) of the European Union's Eighth Framework Programme Horizon 2020 under REA grant agreement number 701704

A simple process for the fabrication of large-area CVD graphene based devices via selective in situ functionalization and patterning

This is the author accepted manuscript. The final version is available from the publisher via the DOI in this record.We report a novel approach for the fabrication of micro- and nano-scale graphene devices via the in-situ plasma functionalization and in-situ lithographic patterning of large-area graphene directly on CVD catalytic metal (Cu) substrates. This enables us to create graphene-based devices in their entirety prior to any transfer processes, simplifying very significantly the device fabrication process and potentially opening up the route to the use of a wider range of target substrates. We demonstrate the capabilities of our technique via the fabrication of a flexible, transparent, graphene/graphene oxide humidity sensor that outperforms a conventional commercial sensor.This work was carried out under the auspices of the EU FP7 project CareRAMM. This project received funding from the European Union Seventh Framework Programme (FP7/2007-2013) under grant agreement no 309980. The authors are grateful for helpful discussions with all CareRAMM partners, particularly Prof A. Ferrari and Ms A. Ott at the University of Cambridge, and Dr A. Sebastian and Dr W. Koelmans at IBM Research Zurich. We also gratefully acknowledge the assistance of the National EPSRC XPS User’s Service (NEXUS) at Newcastle University, UK (an EPSRC Mid-Range Facility) in carrying out the XPS measurements and the assistance of Prof S. Russo at the University of Exeter in carrying out humidity sensing measurements. A.M.A. would also like to thank Dr E. Alexeev for useful ideas for this Letter and pleasurable discussions of the result

The Potential Short- and Long-Term Disruptions and Transformative Impacts of 5G and Beyond Wireless Networks: Lessons Learnt from the Development of a 5G Testbed Environment

The capacity and coverage requirements for 5 th generation (5G) and beyond wireless connectivity will be significantly different from the predecessor networks. To meet these requirements, the anticipated deployment cost in the United Kingdom (UK) is predicted to be between £30bn and £50bn, whereas the current annual capital expenditure (CapEX) of the mobile network operators (MNOs) is £2.5bn. This prospect has vastly impacted and has become one of the major delaying factors for building the 5G physical infrastructure, whereas other areas of 5G are progressing at their speed. Due to the expensive and complicated nature of the network infrastructure and spectrum, the second-tier operators, widely known as mobile virtual network operators (MVNO), are entirely dependent on the MNOs. In this paper, an extensive study is conducted to explore the possibilities of reducing the 5G deployment cost and developing viable business models. In this regard, the potential of infrastructure, data, and spectrum sharing is thoroughly investigated. It is established that the use of existing public infrastructure (e.g., streetlights, telephone poles, etc.) has a potential to reduce the anticipated cost by about 40% to 60%. This paper also reviews the recent Ofcom initiatives to release location-based licenses of the 5G-compatible radio spectrum. Our study suggests that simplification of infrastructure and spectrum will encourage the exponential growth of scenario-specific cellular networks (e.g., private networks, community networks, micro-operators) and will potentially disrupt the current business models of telecommunication business stakeholders - specifically MNOs and TowerCos. Furthermore, the anticipated dense device connectivity in 5G will increase the resolution of traditional and non-traditional data availability significantly. This will encourage extensive data harvesting as a business opportunity and function within small and medium-sized enterprises (SMEs) as well as large social networks. Consequently, the rise of new infrastructures and spectrum stakeholders is anticipated. This will fuel the development of a 5G data exchange ecosystem where data transactions are deemed to be high-value business commodities. The privacy and security of such data, as well as definitions of the associated revenue models and ownership, are challenging areas - and these have yet to emerge and mature fully. In this direction, this paper proposes the development of a unified data hub with layered structured privacy and security along with blockchain and encrypted off-chain based ownership/royalty tracking. Also, a data economy-oriented business model is proposed. The study found that with the potential commodification of data and data transactions along with the low-cost physical infrastructure and spectrum, the 5G network will introduce significant disruption in the Telco business ecosystem

Multilevel ultrafast flexible nanoscale nonvolatile hybrid graphene oxide-titanium oxide memories

This is the author accepted manuscript. The final version is available from the publisher via the DOI in this record.Graphene oxide (GO) resistive memories offer the promise of low-cost environmentally sustainable fabrication, high mechanical flexibility and high optical transparency, making them ideally suited to future flexible and transparent electronics applications. However, the dimensional and temporal scalability of GO memories, i.e., how small they can be made and how fast they can be switched, is an area that has received scant attention. Moreover, a plethora of GO resistive switching characteristics and mechanisms has been reported in the literature, sometimes leading to a confusing and conflicting picture. Consequently, the potential for graphene oxide to deliver high-performance memories operating on nanometer length and nanosecond time scales is currently unknown. Here we address such shortcomings, presenting not only the smallest (50 nm), fastest (sub-5 ns), thinnest (8 nm) GO-based memory devices produced to date, but also demonstrate that our approach provides easily accessible multilevel (4-level, 2-bit per cell) storage capabilities along with excellent endurance and retention performance-all on both rigid and flexible substrates. Via comprehensive experimental characterizations backed-up by detailed atomistic simulations, we also show that the resistive switching mechanism in our Pt/GO/Ti/Pt devices is driven by redox reactions in the interfacial region between the top (Ti) electrode and the GO layer.This work was carried out under the auspices of the EU FP7 project CareRAMM. This project received funding from the European Union Seventh Framework Programme (FP7/2007- 2013) under grant agreement no. 309980. The authors are grateful for helpful discussions with all CareRAMM partners, particularly Prof. Andrea Ferrari and Ms. Anna Ott at the University of Cambridge, and Drs. Abu Sebastian and Wabe Koelmans at IBM Research Zurich. We also gratefully acknowledge the assistance of the National EPSRC XPS User’s Service (NEXUS) at Newcastle University, U.K. (an EPSRC Mid-Range Facility) in carrying out the XPS measurement

Anisotropic magnetoconductance and Coulomb blockade in defect engineered Cr2Ge2Te6 van der Waals heterostructures

This is the final version. Available from the American Physical Society via the DOI in this record.We demonstrate anisotropic tunnel magnetoconductance by controllably engineering charging islands inthe layered semiconducting ferromagnet Cr2Ge2Te6. This is achieved by assembling vertical van der Waalsheterostructures comprised of graphene electrodes separated by crystals of Cr2Ge2Te6. Carefully applyingvertical electric fields in the region of (E∼25–50 mV/nm) across the Cr2Ge2Te6causes its dielectric breakdownat cryogenic temperatures. This breakdown process has the effect of introducing subgap defect states withinthe otherwise semiconducting ferromagnetic material. Low-temperature electron transport through chargingislands reveals Coulomb blockade behavior with a strongly gate-tuneable anisotropic magnetoconductance,which persists up toT∼60 K. We report average tunnel magnetoresistance values of 100%. This work opensnew avenues and material systems for the development of nanometer-scale electrically controlled spintronicdevices.Royal Academy of Engineering (RAE)Royal SocietyEngineering and Physical Sciences Research Council (EPSRC

New routes to the functionalization patterning and manufacture of graphene-based materials for biomedical applications

This is the author accepted manuscript. The final version is available from Royal Society via the DOI in this record.Graphene-based materials are being widely explored for a range of biomedical applications, from targeted drug delivery to biosensing, bioimaging and use for antibacterial treatments, to name but a few. In many such applications it is not graphene itself that is used as the active agent, but one of its chemically-functionalised forms. The type of chemical species used for functionalisation will play a key role in determining the utility of any graphene-based device in any particular biomedical application, since this determines to a large part its physical, chemical, electrical and optical interactions. However, other factors will also be important in determining the eventual uptake of graphene-based biomedical technologies, in particular the ease and cost of manufacture of proposed device and system designs. In this work we describe three novel routes for the chemical functionalisation of graphene using oxygen, iron chloride and fluorine. We also introduce novel in-situ methods for controlling and patterning such functionalisation on the micro- and nano-scales. Our approaches are readily transferable to large-scale manufacturing, potentially paving the way for the eventual cost-effective production of functionalised graphene-based materials, devices and systems for a range of important biomedical applications.AA, VKN, MFC and CDW acknowledge funding via the EU FP7 project CareRAMM (grant no. 309980). SR and MFC. acknowledge financial support from the Engineering and Physical Sciences Research Council (grant nos. EP/J000396/1, EP/K017160/1, EP/K010050/1, EP/G036101/1, EP/M001024/1, and EP/M002438/1)

Interpretation of inverted photocurrent transients in organic lead halide perovskite solar cells; proof of the field screening by mobile ions and determination of the space charge layer widths

In Methyl Ammonium Lead Iodide (MAPI) perovskite solar cells, screening of the built in field by mobile ions has been proposed as part of the cause of the large hysteresis observed in the current/voltage scans in many cells. We show that photocurrent transients measured immediately (e.g. 100 μs) after a voltage step can provide direct evidence that this field screening exists. Just after a step to forward bias, the photocurrent transients are reversed in sign (i.e. inverted), and the magnitude of the inverted transients can be used to find an upper bound on the width of the space charge layers adjacent to the electrodes. This in turn provides a lower bound on the mobile charge concentration, which we find to be 1 x 10 17 /cm 3 . Using a new photocurrent transient experiment, we show that the space charge layer thickness remains approximately constant as a function of bias, as expected for mobile ions in a solid electrolyte. We also discuss additional characteristics of the inverted photocurrent transients that imply either an unusually stable deep trapping, or a photo effect on the mobile ion conductivity

The iBRA (implant breast reconstruction evaluation) study: protocol for a prospective multi-centre cohort study to inform the feasibility, design and conduct of a pragmatic randomised clinical trial comparing new techniques of implant-based breast reconstruction.

BACKGROUND: Implant-based breast reconstruction (IBBR) is the most commonly performed reconstructive procedure in the UK. The introduction of techniques to augment the subpectoral pocket has revolutionised the procedure, but there is a lack of high-quality outcome data to describe the safety or effectiveness of these techniques. Randomised controlled trials (RCTs) are the best way of comparing treatments, but surgical RCTs are challenging. The iBRA (implant breast reconstruction evaluation) study aims to determine the feasibility, design and conduct of a pragmatic RCT to examine the effectiveness of approaches to IBBR. METHODS/DESIGN: The iBRA study is a trainee-led research collaborative project with four phases:Phase 1 - a national practice questionnaire (NPQ) to survey current practicePhase 2 - a multi-centre prospective cohort study of patients undergoing IBBR to evaluate the clinical and patient-reported outcomesPhase 3- an IBBR-RCT acceptability survey and qualitative work to explore patients' and surgeons' views of proposed trial designs and candidate outcomes.Phase 4 - phases 1 to 3 will inform the design and conduct of the future RCT All centres offering IBBR will be encouraged to participate by the breast and plastic surgical professional associations (Association of Breast Surgery and British Association of Plastic Reconstructive and Aesthetic Surgeons). Data collected will inform the feasibility of undertaking an RCT by defining current practice and exploring issues surrounding recruitment, selection of comparator arms, choice of primary outcome, sample size, selection criteria, trial conduct, methods of data collection and feasibility of using the trainee collaborative model to recruit patients and collect data. DISCUSSION: The preliminary work undertaken within the iBRA study will determine the feasibility, design and conduct of a definitive RCT in IBBR. It will work with the trainee collaborative to build capacity by creating an infrastructure of research-active breast and plastic surgeons which will facilitate future high-quality research that will ultimately improve outcomes for all women seeking reconstructive surgery. TRIAL REGISTRATION: ISRCTN37664281

Atypical Reactivation of Varicella Zoster Virus Associated with Pancreatitis in a Heart Transplant Patient.

BACKGROUND Acute pancreatitis is rare following solid organ transplantation but is associated with high mortality. It has been most commonly reported following renal transplant but can occur with other solid organ transplantations. CASE REPORT A 46-year-old male who had an orthotopic heart transplant 6 months ago presented with a 3-week history of abdominal pain. The patient described it as intermittent, sharp, and stabbing, originating in the periumbilical area and radiating to the back. His lipase was elevated at 232 U/L. Given that the patient\u27s symptoms and lipase were elevated to greater than three times the upper limit of normal, he patient was diagnosed with acute pancreatitis. The patient also mentioned a diffuse itchy rash that started a few days prior to admission. Dermatology was consulted, and given the man\u27s clinical presentation, there was concern for atypical reactivation of varicella zoster virus (VZV). VZV polymerase chain reaction of the vesicles returned positive. The patient was started on acyclovir and his symptoms improved. CONCLUSIONS This is the first reported case of VZV-associated pancreatitis in a heart transplant patient. Our patient presented with acute pancreatitis and was treated supportively. However, he did not receive antiviral treatment until his rash was discovered. Timely treatment of VZV resulted in resolution of both the rash and pancreatitis. Timely diagnosis of pancreatitis and VZV is important to prevent development of multiorgan failure and death