Stable Field Emission from Layered MoS2 Nanosheets in High Vacuum and Observation of 1/f Noise

Field emission and current noise of hydrothermally synthesized MoS2 nanosheets are investigated in ultra-high-vacuum and industrially suited high-vacuum conditions. The study reveals that the emission turn-on field is pressure dependent. Moreover, the MoS2 nano‐sheets exhibit more stable field-electron emission in high- vacuum than in ultra-high-vacuum conditions. The investigations on field-emission current fluctuations show features of 1/f-type noise in ultra-high-vacuum and high-vacuum conditions, attributed to adsorption and desorption processes. The post-field-emission results indicate the MoS2 nanosheets are a robust field emitter in high-vacuum conditions

Anticoagulation for non-valvular atrial aibrillation – towards a new beginning with ximelagatran

OBJECTIVES: Ximelagatran is a novel oral direct thrombin inhibitor. It has favorable pharmacodynamic properties, with a broad therapeutic range without the need for anticoagulation monitoring. We aimed to discover whether ximelagatran offers a genuine future replacement to warfarin for patients in persistent atrial fibrillation (AF). MATERIALS AND METHODS: We provide an evidence-based review of the relative merits and disadvantages of warfarin and aspirin. We subsequently present an overview of the evidence for the utility of ximelagatran in the treatment of AF. RESULTS: Adjusted dose warfarin is recommended over aspirin for patients in AF at high risk of future stroke. Some of this benefit is partially offset by the higher bleeding risks associated with warfarin therapy. The SPORTIF III and V studies have shown that ximelagatran is not inferior to warfarin in the prevention of all strokes in patients with AF (both persistent and paroxysmal). This benefit was partially offset by the finding of a significant elevation of liver transaminases (>3 × normal) in 6% of patients. CONCLUSIONS: Current data would suggest that ximelagatran might represent a future alternative to warfarin. The lack of need for anticoagulant monitoring has been partially offset by a need for regular monitoring of liver function. Further data from randomized clinical trials is clearly needed

Effect of remote ischaemic conditioning on clinical outcomes in patients with acute myocardial infarction (CONDI-2/ERIC-PPCI): a single-blind randomised controlled trial.

BACKGROUND: Remote ischaemic conditioning with transient ischaemia and reperfusion applied to the arm has been shown to reduce myocardial infarct size in patients with ST-elevation myocardial infarction (STEMI) undergoing primary percutaneous coronary intervention (PPCI). We investigated whether remote ischaemic conditioning could reduce the incidence of cardiac death and hospitalisation for heart failure at 12 months. METHODS: We did an international investigator-initiated, prospective, single-blind, randomised controlled trial (CONDI-2/ERIC-PPCI) at 33 centres across the UK, Denmark, Spain, and Serbia. Patients (age >18 years) with suspected STEMI and who were eligible for PPCI were randomly allocated (1:1, stratified by centre with a permuted block method) to receive standard treatment (including a sham simulated remote ischaemic conditioning intervention at UK sites only) or remote ischaemic conditioning treatment (intermittent ischaemia and reperfusion applied to the arm through four cycles of 5-min inflation and 5-min deflation of an automated cuff device) before PPCI. Investigators responsible for data collection and outcome assessment were masked to treatment allocation. The primary combined endpoint was cardiac death or hospitalisation for heart failure at 12 months in the intention-to-treat population. This trial is registered with ClinicalTrials.gov (NCT02342522) and is completed. FINDINGS: Between Nov 6, 2013, and March 31, 2018, 5401 patients were randomly allocated to either the control group (n=2701) or the remote ischaemic conditioning group (n=2700). After exclusion of patients upon hospital arrival or loss to follow-up, 2569 patients in the control group and 2546 in the intervention group were included in the intention-to-treat analysis. At 12 months post-PPCI, the Kaplan-Meier-estimated frequencies of cardiac death or hospitalisation for heart failure (the primary endpoint) were 220 (8·6%) patients in the control group and 239 (9·4%) in the remote ischaemic conditioning group (hazard ratio 1·10 [95% CI 0·91-1·32], p=0·32 for intervention versus control). No important unexpected adverse events or side effects of remote ischaemic conditioning were observed. INTERPRETATION: Remote ischaemic conditioning does not improve clinical outcomes (cardiac death or hospitalisation for heart failure) at 12 months in patients with STEMI undergoing PPCI. FUNDING: British Heart Foundation, University College London Hospitals/University College London Biomedical Research Centre, Danish Innovation Foundation, Novo Nordisk Foundation, TrygFonden

Diagnostics of advanced diesel fuel injectors

During manufacture, variations in fuel injector dimensions result in variations in fuel metering. Thus injectors need to be calibrated at the end of the production-line and then matched with engines to achieve desired fueling characteristics. Over time, injectors can wear in, resulting in changes in fuel dosing. Since measuring injected fuel quantities can be inconvenient, various estimation techniques exist. The Virtual Sensor Coefficient method for injected fuel quantity estimation is based on the concept of Bulk Modulus. This concept uses the fact that outflow of fuel from the rail at every injection event leads to corresponding measurable pressure changes inside the rail. Consequently, the magnitude of pressure change can be used to predict the change in fuel flow and hence the amount of fuel actually injected during an injection event. The most crucial parameter in this concept is Rail Pressure. It is known that disturbances in the pressure signal lead to inaccurate measurements of pressure drop. This leads to inaccurate computations of the system bulk modulus and hence the injected quantity of fuel. This project explores ways to process the pressure signal appropriately so that the pressure drops corresponding to the injection events could be measured accurately. Three methods are proposed, implemented and their results compared. These methods are the two-window based dominant frequency method, filtering using IIR filters and de-noising using wavelet transforms. It is seen that the first method is the simplest method to implement relative to the other two methods while the results obtained after using the second and the third methods are relatively better. For higher rail pressures (2000-2600 bar) the de-noising method fares the best with consistent % error numbers of +/-4 over a large range of on-times. While for the same pressure range, the two-window based dominant frequency method, on the other hand, shows % errors that fall in the range of +/-12 for the same range of on-times. This project also identifies the issues that affect the implementation of the VSC concept. These are quantization and corruption of data due to pumping effects. These are more significant at the lower rail pressures and on-times. An algorithm is devised in order to detect the pumping affected data with an aim to \u27weed-out\u27 such data and work with only the good data so that the VSC concept could give acceptable results

Remarkably low turn-on field emission in undoped, nitrogen-doped, and boron-doped graphene

Field emission studies have been carried out on undoped as well as N- and B-doped graphene samples prepared by arc-discharge method in a hydrogen atmosphere. These graphene samples exhibit very low turn-on fields. N-doped graphene shows the lowest turn-on field of 0.6 V/μm, corresponding to emission current density of 10 μA/cm2. These characteristics are superior to the other types of nanomaterials reported in the literature. Furthermore, emission currents are stable over the period of more than 3 h for the graphene samples. The observed emission behavior has been explained on the basis of nanometric features of graphene and resonance tunneling phenomenon

Promising field electron emission performance of vertically aligned one dimensional (1D) brookite (β) TiO₂ nanorods

We evidence field-electron emission (FE) studies on the large-area array of one-dimensional (1D) brookite (β) TiO2 nanorods. The pure 1D β-TiO2 nanorods of 10 nm width and 760 nm long were synthesized on Si substrate utilizing hot-filament metal vapor deposition technique. X-ray diffraction (XRD) and transmission electron microscopy (TEM) analysis evidenced the β-TiO2 nanorods to be composed of orthorhombic crystals in brookite (β) phase. X-ray photoemission spectroscopy (XPS) revealed the formation of pure stoichiometric (i.e. 1 : 1.98) 1D TiO2 nanorods. The values of turn-on field, required to draw current density of 10 μA cm−2, was observed 3.9 V μm−1 for pristine 1D β-TiO2 nanorods emitters, which were found significantly lower than doped/undoped 1D TiO2 nanostructures (i.e. nanotubes, nanowires, nanorods) based field emitters. The enhanced FE behavior of the TiO2/Si emitter can be attributed to modulation of electronic properties due to the high aspect ratio of vertically aligned TiO2 nanorods. Furthermore, the orthodox emission situation of pristine TiO2/Si emitters exhibit good emission stability and reveal their potentials as promising FE material.publishe