Fast High-Responsivity Few-Layer MoTe2 Photodetectors

This is the author accepted manuscript. The final version is available from Wiley via the DOI in this record.The Transition Metal Dichalcogenide MoTe2 is fabricated via mechanical exfoliation into few-layer Field Effect Transistors (FETs) having a hole mobility of 2.04 V/cm2/s. Four-layer MoTe2 FETs show a high photoresponsivity of 6 A/W and a response time, at around 160 μs, over 100 times faster than previously reported for MoTe2. Few-layer MoTe2 thus appears as a strong candidate for high speed and high sensitivity photodetection applications.CDW would like to acknowledge funding via EPSRC grants EP/M015173/1 and EP/M015130/1. TJO acknowledges funding from the EPSRC Centre for Doctoral Training in Metamaterials, grant number EP/L015331/

Humidity‐Controlled Ultralow Power Layer‐by‐Layer Thinning, Nanopatterning and Bandgap Engineering of MoTe2

This is the final version. Available on open access from Wiley via the DOI in this recordA highly effective laser thinning method is demonstrated to accurately control the thickness of MoTe2 layers. By utilizing the humidity present in the ambient atmosphere, multilayered MoTe2 films can be uniformly thinned all the way down to monolayer with layer-by-layer precision using an ultralow laser power density of 0.2 mW µm−2. Localized bandgap engineering is also performed in MoTe2, by creating regions with different bandgaps on the same film, enabling the formation of lateral homojunctions with sub-200 nm spatial resolution. Field-effect transistors fabricated from these thinned layers exhibit significantly improved electrical properties with an order of magnitude increase in on/off current ratios, along with enhancements in on-current and field-effect mobility values. Thinned devices also exhibit the fastest photoresponse (45 µs) for an MoTe2-based visible photodetector reported to date, along with a high photoresponsivity. A highly sensitive monolayer MoTe2 photodetector is also reported. These results demonstrate the efficiency of the presented thinning approach in producing high-quality MoTe2 films for electronic and optoelectronic applications.Office of Naval Research GlobalEngineering and Physical Sciences Research Council (EPSRC)Defence Science and Technology Laborator

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)

Role of charge traps in the performance of atomically-thin transistors

Transient currents in atomically thin MoTe2 field-effect transistors (FETs) are measured during cycles of pulses through the gate electrode. The curves of the transient currents are analyzed in light of a newly proposed model for charge-trapping dynamics that renders a time-dependent change in the threshold voltage as the dominant effect on the channel hysteretic behavior over emission currents from the charge traps. The proposed model is expected to be instrumental in understanding the fundamental physics that governs the performance of atomically thin FETs and is applicable to the entire class of atomically thin-based devices. Hence, the model is vital to the intelligent design of fast and highly efficient optoelectronic devices

Avoiding catastrophic failure in correlated networks of networks

Networks in nature do not act in isolation but instead exchange information, and depend on each other to function properly. An incipient theory of Networks of Networks have shown that connected random networks may very easily result in abrupt failures. This theoretical finding bares an intrinsic paradox: If natural systems organize in interconnected networks, how can they be so stable? Here we provide a solution to this conundrum, showing that the stability of a system of networks relies on the relation between the internal structure of a network and its pattern of connections to other networks. Specifically, we demonstrate that if network inter-connections are provided by hubs of the network and if there is a moderate degree of convergence of inter-network connection the systems of network are stable and robust to failure. We test this theoretical prediction in two independent experiments of functional brain networks (in task- and resting states) which show that brain networks are connected with a topology that maximizes stability according to the theory.Comment: 40 pages, 7 figure

Imaging spontaneous currents in superconducting arrays of pi-junctions

Superconductors separated by a thin tunneling barrier exhibit the Josephson effect that allows charge transport at zero voltage, typically with no phase shift between the superconductors in the lowest energy state. Recently, Josephson junctions with ground state phase shifts of pi proposed by theory three decades ago have been demonstrated. In superconducting loops, pi-junctions cause spontaneous circulation of persistent currents in zero magnetic field, analogous to spin-1/2 systems. Here we image the spontaneous zero-field currents in superconducting networks of temperature-controlled pi-junctions with weakly ferromagnetic barriers using a scanning SQUID microscope. We find an onset of spontaneous supercurrents at the 0-pi transition temperature of the junctions Tpi = 3 K. We image the currents in non-uniformly frustrated arrays consisting of cells with even and odd numbers of pi-junctions. Such arrays are attractive model systems for studying the exotic phases of the 2D XY-model and achieving scalable adiabatic quantum computers.Comment: Pre-referee version. Accepted to Nature Physic

Effects of ocean acidification on invertebrate settlement at volcanic CO<inf>2</inf> vents

We present the first study of the effects of ocean acidification on settlement of benthic invertebrates and microfauna. Artificial collectors were placed for 1 month along pH gradients at CO2 vents off Ischia (Tyrrhenian Sea, Italy). Seventy-nine taxa were identified from six main taxonomic groups (foraminiferans, nematodes, polychaetes, molluscs, crustaceans and chaetognaths). Calcareous foraminiferans, serpulid polychaetes, gastropods and bivalves showed highly significant reductions in recruitment to the collectors as pCO2 rose from normal (336-341 ppm, pH 8.09-8.15) to high levels (886-5,148 ppm) causing acidified conditions near the vents (pH 7.08-7.79). Only the syllid polychaete Syllis prolifera had higher abundances at the most acidified station, although a wide range of polychaetes and small crustaceans was able to settle and survive under these conditions. A few taxa (Amphiglena mediterranea, Leptochelia dubia, Caprella acanthifera) were particularly abundant at stations acidified by intermediate amounts of CO2 (pH 7. 41-7.99). These results show that increased levels of CO2 can profoundly affect the settlement of a wide range of benthic organisms. © 2010 Springer-Verlag

Phase I Trial of the Human Double Minute 2 Inhibitor MK-8242 in Patients With Advanced Solid Tumors.

Purpose To evaluate MK-8242 in patients with wild-type TP53 advanced solid tumors. Patients and Methods MK-8242 was administered orally twice a day on days 1 to 7 in 21-day cycles. The recommended phase II dose (RP2D) was determined on the basis of safety, tolerability, pharmacokinetics (PK), and by mRNA expression of the p53 target gene pleckstrin homology-like domain, family A, member 3 ( PHLDA3). Other objectives were to characterize the PK/pharmacodynamic (PD) relationship, correlate biomarkers with response, and assess tumor response. Results Forty-seven patients received MK-8242 across eight doses that ranged from 60 to 500 mg. Initially, six patients developed dose-limiting toxicities (DLTs): grade (G) 2 nausea at 120 mg; G3 fatigue at 250 mg; G2 nausea and G4 thrombocytopenia at 350 mg; and G3 vomiting and G3 diarrhea at 500 mg. DLT criteria were revised to permit management of GI toxicities. Dosing was resumed at 400 mg, and four additional DLTs were observed: G4 neutropenia and G4 thrombocytopenia at 400 mg and G4 thrombocytopenia (two patients) at 500 mg. Other drug-related G3 and G4 events included anemia, leukopenia, pancytopenia, nausea, hyperbilirubinemia, hypophosphatemia, and anorexia. On the basis of safety, tolerability, PK, and PD, the RP2D was established at 400 mg (15 evaluable patients experienced two DLTs). PK for 400 mg (day 7) showed Cmax 3.07 μM, Tmax 3.0 hours, t1/2 (half-life) 6.6 hours, CL/F (apparent clearance) 28.9 L/h, and Vd/F (apparent volume) 274 L. Blood PHLDA3 mRNA expression correlated with drug exposure ( R(2) = 0.68; P < .001). In 41 patients with postbaseline scans, three patients with liposarcoma achieved a partial response (at 250, 400, and 500 mg), 31 showed stable disease, and eight had progressive disease. In total, 27 patients with liposarcoma had a median progression-free survival of 237 days. Conclusion At the RP2D of 400 mg twice a day, MK-8242 activated the p53 pathway with an acceptable safety and tolerability profile. The observed clinical activity (partial response and prolonged progression-free survival) provides an impetus for further study of HDM2 inhibitors in liposarcoma