Recent work using an improved design of an unbalanced magnetron in a four-magnetron closed-field arrangement has resulted in exceptionally high ion current densities at the substrates during both ion ...cleaning and deposition. The ion current at the electrically biased substrate is increased by a factor of close to 100 as compared to balanced magnetrons of the same polarity. The absolute ion current is dependent on a number of factors which are discussed, the most important being the power applied to the magnetrons. The relationship between substrate bias and ion current is presented. It is found that it is possible to achieve very high ion currents at bias voltages as low as −50
V. The effect of the substrate bias voltage and the substrate ion current on the coating structure have been studied, and it is found that the optimum conditions for the deposition of dense coherent coatings with low internal stresses are a high ion current at a low bias voltage. These conditions are readily achieved using the closed-field unbalanced magnetron technique. It is shown that coating structure is almost independent of deposition rate, which is extremely important for the deposition of coatings with excellent structures at low temperatures. Ion cleaning prior to deposition is carried out with the magnetrons operating at low power. This allows the plasma discharge to strike and be maintained at low argon pressures, thus avoiding contamination from the chamber walls, etc. The enhancement of the ion current under these conditions is similar to that achieved during deposition, i.e. around 100×, and so the efficiency of ion cleaning is considerably enhanced, producing a “clean” surface which results in excellent adhesion. Scratch adhesion testing has been used to compare the critical loads for coatings deposited with different cleaning conditions and the excellent adhesion achievable is demonstrated.
A novel magnetron sputtering technique is described for the deposition of durable, high surface area metal and alloy deposits (thickness up to several microns) onto nickel and steel substrates. The ...materials deposited include platinum, nickel, nickel alloys and steels. The structure of the deposits is characterised and it is demonstrated that some high surface area coatings are efficient and effective electrocatalysts for hydrogen evolution in alkaline media and coated mesh electrodes have been tested in a modern water electrolyser configuration.
•High surface area coatings were deposited by a magnetron sputtering technique.•The high surface area coatings show excellent adhesion and uniformity.•The coatings of Ni and Pt give a roughness factor of ∼240.•NiMo coating is excellent catalyst for H2 evolution approaching overpotential for Pt.•A water electrolyser cell voltage of 2.1 V is achieved with NiMo coating at 1 A cm−2.
The structure of two-component coatings codeposited by magnetron sputter ion plating was studied. This apparently simple topic has never been studied systematically and has led to a number of ...unexpected and very interesting results.The systems that were studied included materials with 100% solid-solubility, (titanium and zirconium) totally insoluble materials (chromium and copper) and materials that can form intermetallic compounds (titanium and aluminium). Variables studied included method of deposition, composition of the coating and energy of ion bombardment during deposition. Two approaches were used for the deposition process. These were multilayer deposition from vertically opposed magnetrons and codeposition from coplanar magnetrons, both using closed field magnetic arrays. Both methods are fundamentally the same. It is the orientation and manipulation of the substrates during the deposition process which leads to either a multilayer coating structure or a codeposited homogeneous coating. The flexibility of the coating technique was demonstrated and a greater understanding was gained of both the structure and properties of alloy coatings and how these are influenced by the deposition parameters in a magnetron sputtering system. The coating structures were studied using SEM and XRD and their properties by different mechanical tests. Prior studies in this field have shown that such coatings can have unexpected properties. For example, energetic ion bombardment is known to cause the production of 'non equilibrium' phases and can extend the normal solubility range. Thus HCP Ti-Al coatings can be deposited which would be expected to have good tribological properties. Properties such as this have been studied and exploited for suitable applications. Further studies showed how parameters such as ion current density are dependant on target current and have a large influence on coating structures and properties. This is all of importance to materials scientists, surface engineers and manufacturers of coating equipment.
The structure of two-component coatings codeposited by magnetron sputter ion plating was studied. This apparently simple topic has never been studied tematically and has led to a number of unexpected ...and very interesting results.
In the past, MoS
2 coatings deposited by sputtering have consisted of a first few layers with a dense coherent structure followed by an open columnar structure, with only the first few layers ...providing any wear resistance. The high ion-current densities at low substrate bias voltages, characteristic of the closed-field unbalanced magnetron sputter ion-plating system, produce MoS
2 coatings that are dense, coherent and adherent with very good tribological properties. The tribological properties of these coatings have been tested by using reciprocating and pin-on-disc friction and wear machines, and the results are presented. The properties of the coatings were improved by optimising the deposition parameters, in particular by reducing the amount of water vapour present in the atmosphere of the coating system. It has been found that the properties can be further improved by the co-deposition of small amounts of metal with the MoS
2. The equipment and deposition methods are described. The MoS
2/metal composite coatings were harder, much more wear-resistant and also less sensitive to water vapour in the testing atmosphere. They gave excellent wear resistance at loads as high as 140
N on the reciprocating wear tester using a 6
mm diameter WC pin. The coefficient of friction was as low as 0.02 at a humidity of 40%, and the coatings and adhesion scratch tests indicated critical loads of >120
N. The composite coatings have been studied by micro hardness testing, scratch adhesion testing, pin-on-disc and reciprocating friction and wear tests. The structure of the coatings was studied by optical microscopy and scanning electron microscopy of normal sections and taper sections produced by ball cratering techniques. Some applications, including the coating of cutting and forming tools, are described.
Preliminary evidence has highlighted a possible association between severe COVID-19 and persistent cognitive deficits. Further research is required to confirm this association, determine whether ...cognitive deficits relate to clinical features from the acute phase or to mental health status at the point of assessment, and quantify rate of recovery.
46 individuals who received critical care for COVID-19 at Addenbrooke's hospital between 10th March 2020 and 31st July 2020 (16 mechanically ventilated) underwent detailed computerised cognitive assessment alongside scales measuring anxiety, depression and post-traumatic stress disorder under supervised conditions at a mean follow up of 6.0 (± 2.1) months following acute illness. Patient and matched control (N = 460) performances were transformed into standard deviation from expected scores, accounting for age and demographic factors using N = 66,008 normative datasets. Global accuracy and response time composites were calculated (G_SScore & G_RT). Linear modelling predicted composite score deficits from acute severity, mental-health status at assessment, and time from hospital admission. The pattern of deficits across tasks was qualitatively compared with normal age-related decline, and early-stage dementia.
COVID-19 survivors were less accurate (G_SScore=-0.53SDs) and slower (G_RT=+0.89SDs) in their responses than expected compared to their matched controls. Acute illness, but not chronic mental health, significantly predicted cognitive deviation from expected scores (G_SScore (p=0.0037) and G_RT (p = 0.0366)). The most prominent task associations with COVID-19 were for higher cognition and processing speed, which was qualitatively distinct from the profiles of normal ageing and dementia and similar in magnitude to the effects of ageing between 50 and 70 years of age. A trend towards reduced deficits with time from illness (r∼=0.15) did not reach statistical significance.
Cognitive deficits after severe COVID-19 relate most strongly to acute illness severity, persist long into the chronic phase, and recover slowly if at all, with a characteristic profile highlighting higher cognitive functions and processing speed.
This work was funded by the National Institute for Health Research (NIHR) Cambridge Biomedical Research Centre (BRC), NIHR Cambridge Clinical Research Facility (BRC-1215-20014), the Addenbrooke's Charities Trust and NIHR COVID-19 BioResource RG9402. AH is funded by the UK Dementia Research Institute Care Research and Technology Centre and Imperial College London Biomedical Research Centre. ETB and DKM are supported by NIHR Senior Investigator awards. JBR is supported by the Wellcome Trust (220258) and Medical Research Council (SUAG/051 G101400). VFJN is funded by an Academy of Medical Sciences/ The Health Foundation Clinician Scientist Fellowship. The views expressed are those of the authors and not necessarily those of the NHS, the NIHR or the Department of Health and Social Care.
IntroductionGlucagon-like peptide-1 receptor agonists (GLP-1 RAs), currently marketed for type 2 diabetes and obesity, may offer novel mechanisms to delay or prevent neurotoxicity associated with ...Alzheimer’s disease (AD). The impact of semaglutide in amyloid positivity (ISAP) trial is investigating whether the GLP-1 RA semaglutide reduces accumulation in the brain of cortical tau protein and neuroinflammation in individuals with preclinical/prodromal AD.Methods and analysisISAP is an investigator-led, randomised, double-blind, superiority trial of oral semaglutide compared with placebo. Up to 88 individuals aged ≥55 years with brain amyloid positivity as assessed by positron emission tomography (PET) or cerebrospinal fluid, and no or mild cognitive impairment, will be randomised. People with the low-affinity binding variant of the rs6971 allele of the Translocator Protein 18 kDa (TSPO) gene, which can interfere with interpreting TSPO PET scans (a measure of neuroinflammation), will be excluded.At baseline, participants undergo tau, TSPO PET and MRI scanning, and provide data on physical activity and cognition. Eligible individuals are randomised in a 1:1 ratio to once-daily oral semaglutide or placebo, starting at 3 mg and up-titrating to 14 mg over 8 weeks. They will attend safety visits and provide blood samples to measure AD biomarkers at weeks 4, 8, 26 and 39. All cognitive assessments are repeated at week 26. The last study visit will be at week 52, when all baseline measurements will be repeated. The primary end point is the 1-year change in tau PET signal.Ethics and disseminationThe study was approved by the West Midlands—Edgbaston Research Ethics Committee (22/WM/0013). The results of the study will be disseminated through scientific presentations and peer-reviewed publications.Trial registration number ISRCTN71283871.
Since 1988, the American Society for Clinical Pathology (ASCP) has conducted its Wage and Vacancy Survey to provide the most recent wage data and determine the extent and distribution of shortages ...within the nation's clinical laboratory workforce. This confidential survey has been administered every two years and has served as the primary source of information for academic, government, and industry labor analysts. While continuity remains a central objective in monitoring trends, the survey has evolved in response to changes within the profession and new questions have been added to the 2011 survey to examine some of the factors affecting wage and vacancy rates. DeFranco et al feature the ASCP's 2011 Vacancy Survey of US Clinical Laboratories.
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