Oxide nanotemplates for self-assembling "solid" building blocks

It is widely accepted that self-assembling building blocks is one of the promising ways for engineering new materials. Recent years reveal substantial progress in fabricating colloidal particles, polymer blocks and supramolecular aggregates of organic molecules. Despite of substantial progress in molecular self-assembly there is still a lack of simple blocks made of "solid matter" (e.g. metals, oxides etc.) with well-defined crystal structure and spatial order. Here we demonstrate that ordered arrays of metal nanoclusters can be fabricated by self-assembly on a wide range of oxide templates. These nano-templates are produced either by depositing an alien oxide film or by oxidizing a metal/metal oxide substrate.Comment: 11 pages, 2 figures added DFT calculations and Fig.

Self-assembly of iron nanoclusters on the Fe3O4(111) superstructured surface

We report on the self-organized growth of a regular array of Fe nanoclusters on a nanopatterned magnetite surface. Under oxidizing preparation conditions the (111) surface of magnetite exhibits a regular superstructure with three-fold symmetry and a 42 A periodicity. This superstructure represents an oxygen terminated (111) surface, which is reconstructed to form a periodically strained surface. This strain patterned surface has been used as a template for the growth of an ultrathin metal film. A Fe film of 0.5 A thickness was deposited on the substrate at room temperature. Fe nanoclusters are formed on top of the surface superstructure creating a regular array with the period of the superstructure. We also demonstrate that at least the initial stage of Fe growth occurs in two-dimensional mode. In the areas of the surface where the strain pattern is not formed, random nucleation of Fe was observed.Comment: 6 pages, 3 figure

Dynamic scanning probe microscopy of adsorbed molecules on graphite

We have used a combined dynamic scanning tunneling and atomic force microscope to study the organisation of weakly bound adsorbed molecules on a graphite substrate. Specifically we have acquired images of islands of the perylene derivative molecules. These weakly bound molecules may be imaged in dynamic STM, in which the probe is oscillated above the surface. We show that molecular resolution may be readily attained and that a similar mode of imaging may be realised using conventional STM arrangement. We also show, using tunnelling spectroscopy, the presence of an energy gap for the adsorbed molecules confirming a weak molecule-substrate interaction.Comment: 11 pages, 2 figure

Investigation of the economic impact of different patterns of medication monitoring in general practices

Medication monitoring is used in primary care to guide treatment and protect the patient from adverse drug events (ADEs). Early detection of ADEs may prevent their development and avoid serious or permanent effects to patient health. Published guidelines for the conduct of medication monitoring in UK primary care recommend monitoring in patients with long-term prescription of certain cardiovascular medications, including angiontensin-converting enzyme inhibitors (ACEI), loop diuretics and amiodarone. Although much evidence exists on the practice of monitoring of these medications in primary care, few studies have considered the effect of carrying out monitoring at different frequencies during long-term therapy on the risk of ADEs. Similarly, evidence of the economic effect of regular monitoring of these medications is sparse. As a consequence, policy-makers rely primarily on evidence from expert opinion as a basis for recommendations and compliance to guidelines in practice is poor. This programme of research aimed to gain an understanding of the nature of monitoring of ACEI, loop diuretics and amiodarone in primary care in England, and investigate the effectiveness and cost-effectiveness of monitoring in accordance with current guidelines. Using electronic health records from the Clinical Practice Research Datalink (CPRD) and Hospital Episode Statistics (HES), a cohort study was carried out in order to quantify the effect of monitoring the study medications at different frequencies during the course of long-term therapy. Weights based on propensity scores were used to control for confounding arising from non-random assignment into alternative monitoring regimens in retrospectively observed data. The time-to-event analysis found that conducting thyroid function tests (TFT) in amiodarone therapy below the recommended interval of once in 6 months was associated with more than a two-fold increase in the hazard rate of hypothyroidism (HR 2.79; 95% CI 1.42,5.47), thyrotoxicity (HR 2.57; 1.40,4.74) and major adverse cardiovascular events (HR 2.13; 1.31,3.45), when comparing against a group of patients monitored according to guidelines. Conversely, conducting urea & electrolyte monitoring in ACEI therapy below recommended frequency was associated with a reduced rate of hyperkalaemia treated in primary care (HR 0.57; 0.42,0.77) and hospital admission (HR 0.13;0.02,0.95). In addition, monitoring urea & electrolytes during loop diuretic therapy below recommended frequency was associated with a lower hazard rate of hypokalaemia or hyponatraemia treated in primary care (HR 0.17; 0.06,0.45). These findings support current recommendations on frequency of regular monitoring in the case of amiodarone TFT monitoring, but not in the case of ACEI or loop diuretics. The results of the time-to-event analysis of amiodarone monitoring were used to populate a decision-analytic model designed in order to estimate the cost-effectiveness of different strategies of monitoring medication, compared to recommended practice. This analysis demonstrated that conducting TFT at recommended frequency yielded modest cost savings per patient (£129, compared to less frequent monitoring and £192 compared to more frequent monitoring option) and utility gains per patient (0.0245 quality-adjusted life-years (QALYs) compared to less frequent monitoring and 0.0543 QALYs compared to more frequent monitoring option). The probabilistic model estimated that the recommended frequency strategy had a 97% probability of being a cost saving option compared to the two alternatives. These findings support the current policy of encouraging 6-monthly monitoring of TFT in amiodarone therapy. This programme of research has demonstrated that medication monitoring is potentially effective and cost-effective in amiodarone therapy, but did not find regular monitoring of ACEI or loop diuretic therapy to be effective. Observational research using routinely collected electronic health records can be used to gauge both the clinical and cost-effectiveness of medication monitoring in order to guide practice in this area and improve the safety of medications in primary care

Atomically Resolved Spin-Dependent Tunnelling on the Oxygen-Terminated Fe3O4 (111)

We employ spin-polarized (SP) STM to study the spin-dependent tunneling between a magnetite (111) sample and an antiferromagnetic tip through a vacuum barrier at room temperature. Atomic scale STM images show significant magnetic contrast corresponding to variations in the local surface states induced by oxygen vacancies. The estimated variations in tunneling magnetoresistance (TMR) of 250% suggest that the spin-transport properties are significantly altered locally by the presence of surface defects.Comment: 10 pages, 4 figure

Estimated societal costs of stroke in the UK based on a discrete event simulation

Background There around 100,000 new stroke cases and over a million people living with its consequences annually in the United Kingdom (UK). This has large impacts on health and social care, unpaid carers and lost productivity. We aimed to estimate associated costs. Methods We estimated 2014/15 annual mean cost per person and aggregate UK cost of stroke for individuals aged ≥40 from a societal perspective. Health and social care costs in the first and subsequent years after stroke were estimated from discrete event simulation modelling, with probability of progression and length of receipt of different health and social care services obtained from routine registry and audit data. Unpaid care hours and lost productivity were obtained from trial data. UK unit costs were applied to estimate mean costs. Epidemiological estimates of stroke incidence and prevalence were then applied to estimate aggregate costs for the UK. Results Mean cost of new-onset stroke is £45,409 (95% CI 42,054-48,763) in the first year after stroke and £24,778 (20,234-29,322) in subsequent years. Aggregate societal cost of stroke is £26 billion per year, including £8.6 billion for NHS and social care. The largest component of total cost was unpaid care (61%) and, given high survival, £20.6 billion related to ongoing care. Conclusion The estimated aggregate cost of stroke substantially exceeds previous UK estimates. Since most of the cost is attributed to unpaid care, interventions aimed at rehabilitation and reducing new and recurrent stroke are likely to yield substantial benefits to carers and cost savings to society

Method for increasing sensitivity of shear-force distance control for scanning near-field microscopy

Scanning-near field optical microscopy requires a distance control mechanism. In most cases, it is based on the shear-force detection. In this paper we report how the performance of the shear-force detection based on the most common nonoptical approach, a Quartz tuning fork, can be improved. Our approach is based on exciting oscillations in just one arm of the fork, not two. This approach reduces the response time of the shear-force detection system. We also introduce an ultra-sensitive system with a long free fiber tip. © 1999 Elsevier Science B.V. All rights reserved

Highly Stable and Reactive Platinum Single Atoms on Oxygen Plasma-Functionalized CeO₂ Surfaces: Nanostructuring and Peroxo Effects

Atomically dispersed precious metals on oxide supports have recently become increasingly interesting catalytic materials. Nonetheless, their non-trivial preparation and limited thermal and environmental stability constitutes an issue for their potential applications. Here we demonstrate that an oxygen plasma pre-treatment of the ceria (CeO2 ) surface serves to anchor Pt single atoms, making them active and resistant towards sintering in the CO oxidation reaction. Through a combination of experimental results obtained on well-defined CeO2 films and theory, we show that the O2 plasma causes surface nanostructuring and the formation of surface peroxo (O22-) species, favoring the uniform and dense distribution of isolated strongly bonded Pt2+ atoms. The promotional effect of the plasma treatment was further demonstrated on the powder Pt/CeO2 catalysts. We believe that plasma functionalization can be applied to other metal/oxide systems to achieve tunable and stable catalysts with a high density of active sites