404 research outputs found

    The high-pressure phase of boron, {\gamma}-B28: disputes and conclusions of 5 years after discovery

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    {\gamma}-B28 is a recently established high-pressure phase of boron. Its structure consists of icosahedral B12 clusters and B2 dumbbells in a NaCl-type arrangement (B2){\delta}+(B12){\delta}- and displays a significant charge transfer {\delta}~0.5- 0.6. The discovery of this phase proved essential for the understanding and construction of the phase diagram of boron. {\gamma}-B28 was first experimentally obtained as a pure boron allotrope in early 2004 and its structure was discovered in 2006. This paper reviews recent results and in particular deals with the contentious issues related to the equation of state, hardness, putative isostructural phase transformation at ~40 GPa, and debates on the nature of chemical bonding in this phase. Our analysis confirms that (a) calculations based on density functional theory give an accurate description of its equation of state, (b) the reported isostructural phase transformation in {\gamma}-B28 is an artifact rather than a fact, (c) the best estimate of hardness of this phase is 50 GPa, (d) chemical bonding in this phase has a significant degree of ionicity. Apart from presenting an overview of previous results within a consistent view grounded in experiment, thermodynamics and quantum mechanics, we present new results on Bader charges in {\gamma}-B28 using different levels of quantum-mechanical theory (GGA, exact exchange, and HSE06 hybrid functional), and show that the earlier conclusion about significant degree of partial ionicity in this phase is very robust

    Biomolecular condensation of the microtubule-associated protein tau.

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    Cells contain multiple compartments dedicated to the regulation and control of biochemical reactions. Cellular compartments that are not surrounded by membranes can rapidly form and dissolve in response to changes in the cellular environment. The physicochemical processes that underlie the formation of non-membrane-bound compartments in vivo are connected to liquid-liquid phase separation of proteins and nucleic acids in vitro. Recent evidence suggests that the protein tau, which plays an important role in Alzheimer's disease and other neurodegenerative disorders, phase separates in solution, forms tau phases with microtubules, and associates with phase-separated RNA-binding protein granules in cells. Here we review the experimental evidence that supports the ability of tau to phase separate in solution and form biomolecular condensates in cells. As for other disease-relevant proteins, the physiological and pathological functions of tau are tightly connected - through loss of normal function or gain of toxic function - and we therefore discuss how tau phase separation plays a role for both, and with respect to different cellular functions of tau

    Performance of the CMS Cathode Strip Chambers with Cosmic Rays

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    The Cathode Strip Chambers (CSCs) constitute the primary muon tracking device in the CMS endcaps. Their performance has been evaluated using data taken during a cosmic ray run in fall 2008. Measured noise levels are low, with the number of noisy channels well below 1%. Coordinate resolution was measured for all types of chambers, and fall in the range 47 microns to 243 microns. The efficiencies for local charged track triggers, for hit and for segments reconstruction were measured, and are above 99%. The timing resolution per layer is approximately 5 ns

    Performance and Operation of the CMS Electromagnetic Calorimeter

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    The operation and general performance of the CMS electromagnetic calorimeter using cosmic-ray muons are described. These muons were recorded after the closure of the CMS detector in late 2008. The calorimeter is made of lead tungstate crystals and the overall status of the 75848 channels corresponding to the barrel and endcap detectors is reported. The stability of crucial operational parameters, such as high voltage, temperature and electronic noise, is summarised and the performance of the light monitoring system is presented

    Factors influencing attitudes toward vaccine safety and vaccine effectiveness amongst UK healthcare professionals prior to and at the time of COVID-19 vaccine rollout: Insights from the CoPE-HCP cohort study.

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    Given the potential for nosocomial outbreaks, we must understand factors associated with negative vaccine attitudes amongst healthcare professionals (HCPs) before the rollout of a newly developed vaccine in a pandemic setting. The aim of this prospective cohort study was to study the impact of preexisting and prevailing mental health on United Kingdom HCPs' attitudes towards a newly developed COVID-19 vaccine. Two online surveys were distributed: first during vaccine development (July-September, 2020) and second during nationwide vaccine rollout (December 2020-March 2021). Mental health (PHQ-9 for depression; GAD-7 for anxiety) was assessed in both surveys. Negative attitude regarding vaccine safety and vaccine effectiveness was assessed at vaccine rollout. A series of logistic regression models were developed relating mental health (preexisting during vaccine development, ongoing and new-onset during rollout, and changes in symptom severity) to negative vaccine attitudes. In 634 HCPs, the presence of depression and/or anxiety during vaccine development was associated with elevated negative attitude towards vaccine safety (adj. OR 1.74 [95% CI 1.10-2.75], p = .02), but not vaccine effectiveness (1.13 [0.77-1.66], p = .53) at rollout. This was independent of other characteristics: age, ethnicity, professional role, and history of contracting COVID-19. Ongoing depression and/or anxiety (1.72 [1.10-2.69], p = .02) was associated with elevated negative attitude regarding vaccine effectiveness, but not vaccine safety. Worsened combined symptom scores over time were associated with elevated negative vaccine effectiveness attitudes (1.03 [1.00-1.05], p < .05), but not vaccine safety. Overall, adverse mental health can impact on HCPs' attitudes towards a newly developed vaccine. Further work is required to understand how this translates to vaccine uptake

    Improved lifestyle is associated with improved depression, anxiety and well-being over time in UK healthcare professionals during the COVID-19 pandemic: insights from the CoPE-HCP cohort study.

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    BACKGROUND: One potential modifiable factor to improve the mental health of healthcare professionals (HCPs) during the pandemic is lifestyle. AIMS: This study aimed to assess whether an improved lifestyle during the pandemic is associated with improved mental health symptoms and mental well-being in HCPs over time. METHODS: This was a cohort study involving an online survey distributed at two separate time points during the pandemic (baseline (July-September 2020) and follow-up (December 2020-March 2021)) to HCPs working in primary or secondary care in the UK. Both surveys assessed for major depressive disorder (MDD) (Patient Health Questionnaire-9 (PHQ-9)), generalised anxiety disorder (GAD) (Generalised Anxiety Disorder-7 (GAD-7)), mental well-being (Short Warwick-Edinburgh Mental Well-being Score (SWEMWBS)) and self-reported lifestyle change (compared with the start of the pandemic) on multiple domains. Cumulative scores were calculated to estimate overall lifestyle change compared with that before the pandemic (at both baseline and follow-up). At each time point, separate logistic regression models were constructed to relate the lifestyle change score with the presence of MDD, GAD and low mental well-being. Linear regression models were also developed relating the change in lifestyle scores from baseline to follow-up to changes in PHQ-9, GAD-7 and SWEMWBS scores. RESULTS: 613 HCPs completed both baseline assessment and follow-up assessment. Consistent significant cross-sectional associations between increased lifestyle change scores and a reduced risk of MDD, GAD and low mental well-being were observed at both baseline and follow-up. Over the study period, a whole unit increase in the change in novel scores (ie, improved overall lifestyle) over 4 months was inversely associated with changes in PHQ-9 (adjusted coefficient: -0.51, 95% confidence interval (CI): -0.73 to -0.30, p<0.001) and GAD-7 scores (adjusted coefficient: -0.32, 95% CI: -0.53 to -0.10, p=0.004) and positively associated with the change in SWEMWBS scores (adjusted coefficient: 0.37, 95% CI: 0.18 to 0.55, p<0.001). CONCLUSIONS: Improved lifestyle over time is associated with improved mental health and mental well-being in HCPs during the pandemic. Improving lifestyle could be a recommended intervention for HCPs to help mitigate the mental health impact during the current and future pandemics. TRIAL REGISTRATION NUMBER: NCT04433260

    A review of geometric dimensioning and tolerancing (GD&T) of additive manufacturing and powder bed fusion lattices

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    Copyright © The Author(s) 2022. To increase industrial adoption, part qualification and certification of the additive manufacturing (AM) process are crucial through geometric benchmarking as well as optimising the properties and process parameters. However, an extensive research gap remains concerning the geometric dimensioning and tolerancing (GD&T) of AM parts. This paper presents a review on the state-of-art GD&T benchmarking of powder bed fusion techniques enabling complex geometrical features like lattices. The study found a lack of design guidelines and standardised measurement techniques for lattice features and profiles.European Union, through a project call “H2020-WIDESPREAD-05-2017-Twinning” Grant number 810708 and project name Increasing Excellence on Advanced Additive Manufacturing (INEX-ADAM)

    Lysine/RNA-interactions drive and regulate biomolecular condensation.

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    Cells form and use biomolecular condensates to execute biochemical reactions. The molecular properties of non-membrane-bound condensates are directly connected to the amino acid content of disordered protein regions. Lysine plays an important role in cellular function, but little is known about its role in biomolecular condensation. Here we show that protein disorder is abundant in protein/RNA granules and lysine is enriched in disordered regions of proteins in P-bodies compared to the entire human disordered proteome. Lysine-rich polypeptides phase separate into lysine/RNA-coacervates that are more dynamic and differ at the molecular level from arginine/RNA-coacervates. Consistent with the ability of lysine to drive phase separation, lysine-rich variants of the Alzheimer's disease-linked protein tau undergo coacervation with RNA in vitro and bind to stress granules in cells. Acetylation of lysine reverses liquid-liquid phase separation and reduces colocalization of tau with stress granules. Our study establishes lysine as an important regulator of cellular condensation
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