Sampling the Materials Space for Conventional Superconducting Compounds.

A large scale study of conventional superconducting materials using a machine-learning accelerated high-throughput workflow is performed, starting by creating a comprehensive dataset of around 7000 electron-phonon calculations performed with reasonable convergence parameters. This dataset is then used to train a robust machine learning model capable of predicting the electron-phonon and superconducting properties based on structural, compositional, and electronic ground-state properties. Using this machine, the transition temperatures (Tc ) of approximately 200 000 metallic compounds are evaluated, all of which are on the convex hull of thermodynamic stability (or close to it) to maximize the probability of synthesizability. Compounds predicted to have Tc values exceeding 5 K are further validated using density-functional perturbation theory. As a result, 541 compounds with Tc values surpassing 10 K, encompassing a variety of crystal structures and chemical compositions, are identified. This work is complemented with a detailed examination of several interesting materials, including nitrides, hydrides, and intermetallic compounds. Particularly noteworthy is LiMoN2 , which is predicted to be superconducting in the stoichiometric trigonal phase, with a Tc exceeding 38 K. LiMoN2 has previously been synthesized in this phase, further heightening its potential for practical applications.

The 2021 room-temperature superconductivity roadmap.

Designing materials with advanced functionalities is the main focus of contemporary solid-state physics and chemistry. Research efforts worldwide are funneled into a few high-end goals, one of the oldest, and most fascinating of which is the search for an ambient temperature superconductor (A-SC). The reason is clear: superconductivity at ambient conditions implies being able to handle, measure and access a single, coherent, macroscopic quantum mechanical state without the limitations associated with cryogenics and pressurization. This would not only open exciting avenues for fundamental research, but also pave the road for a wide range of technological applications, affecting strategic areas such as energy conservation and climate change. In this roadmap we have collected contributions from many of the main actors working on superconductivity, and asked them to share their personal viewpoint on the field. The hope is that this article will serve not only as an instantaneous picture of the status of research, but also as a true roadmap defining the main long-term theoretical and experimental challenges that lie ahead. Interestingly, although the current research in superconductor design is dominated by conventional (phonon-mediated) superconductors, there seems to be a widespread consensus that achieving A-SC may require different pairing mechanisms.In memoriam, to Neil Ashcroft, who inspired us all.

Y2O3:Eu and the Mössbauer isomer shift coefficient of Eu compounds fromab-initiosimulations.

We report on a full potential density functional theory characterization of Y2O3upon Eu doping on the two inequivalent crystallographic sites 24dand 8b. We analyze local structural relaxation, electronic properties and the relative stability of the two sites. The simulations are used to extract the contact charge density at the Eu nucleus. Then we construct the experimental isomer shift (IS) versus contact charge density calibration curve, by considering an ample set of Eu compounds: EuF3, EuO, EuF2, EuS, EuSe, EuTe, EuPd3and the Eu metal. The, expected, linear dependence has a slope ofα= 0.054 mm s-1Å-3, which corresponds to nuclear expansion parameter ΔR/R= 6.0 × 10-5.αallows to obtain an unbiased and accurate estimation of the IS for any Eu compound. We test this approach on two mixed-valence compounds Eu3S4and Eu2SiN3, and use it to predict the Y2O3:Eu IS with the result +1.04 mm s-1at the 24dsite and +1.00 mm s-1at the 8bsite.

Non-continuous positive airway pressure treatment options in obstructive sleep apnoea: A pathophysiological perspective.

The phenotyping of the pathophysiology of obstructive sleep apnoea (OSA) lies at the core of tailored treatments and it is one of the most debated topics in sleep medicine research. Recent sophisticated techniques have broadened the horizon for gaining insight into the variability of the endotypic traits in patients with OSA which account for the heterogeneity in the clinical presentation of the disease and consequently, in the outcome of treatment. However, the implementation of these concepts into clinical practice is still a major challenge for both researchers and clinicians in order to develop tailored therapies targeted to specific endotypic traits that contribute to OSA in each individual patient. This review summarizes available scientific evidence in order to point out the links between endotypic traits (pharyngeal airway collapsibility, upper airway neuromuscular compensation, loop gain and arousal threshold) and the most common non-continuous positive airway pressure (CPAP) treatment options for OSA (mandibular advancement device, upper airway surgery, medication therapy, positional therapy) and to clarify to what extent endotypic traits could help to better predict the success of these therapies. A narrative guide is provided; current design limitations and future avenues of research are discussed, with clinical and research perspectives.

Continuum of care for patients with obstructive sleep apnea after one year from the COVID-19 pandemic onset: no time for further delays: practical issues for a safe and effective management.

Since the SARS-CoV-2 pandemic onset, many routine medical activities have been put on hold and this has deeply affected the management of patients with chronic diseases such as obstructive sleep apnea. Untreated OSA is associated with increased mortality and difficulties in social functioning. A delay in initiating treatment may therefore have harmful consequences. Between February and April 2020, the so-called first wave of the pandemic, the overall activity of sleep centers in Europe was reduced by 80%. As the international infection control authorities released guidelines for SARS-CoV-2 outbreak control, many of the national sleep societies provided strategies for a gradual re-opening of sleep facilities. Most of these strategies were not evidences-based and, in a climate of general concern, worldwide it was strongly advised to post-pone any non-urgent sleep-related procedure. Despite the initial idea that the outbreak could be transient, after one year it is still ongoing and the price we are paying, not only includes deaths caused by COVID-19, but also deaths caused by missed or late diagnosis. As further delays in diagnosing and treating patients with sleep apnea are no more acceptable, a new arrangement of sleep facilities and resources, in order to operate safely and effectively, is now mandatory. In this article, we review most recent literature and guidelines in order to provide practical advice for a new arrangement of sleep laboratories and the care of patients with obstructive sleep apnea after one year from the onset of the COVID-19 pandemic.

Suggestions for lung function testing in the context of COVID-19.

The 2019 coronavirus disease (COVID-19) pandemic is currently a challenge worldwide. Due to the characteristics of lung function tests, the risk of cross infection may be high between health care workers and patients. The role of lung function testing is well defined for the diagnosis of various diseases and conditions. Lung function tests are also indispensable in evaluating the response to medical treatment, in monitoring patient respiratory and systemic pathologies, and in evaluating preoperative risk in cardiothoracic and major abdominal surgeries. However, lung function testing represents a potential route for COVID-19 transmission, due to the aerosol generated during the procedures and the concentration of patients with pulmonary diseases in lung function laboratories. Currently, the opportunities for COVID-19 transmission remain partially unknown, and data are continuously evolving. This review provides useful information on the risks and recommendations for lung function testing, which have varied according to the phase of the pandemic. This information may support national and regional boards and the health authorities to which they belong. There is a need for rapid re-opening of lung function laboratories, but maximum safety is required in the COVID-19 era.

Quantum crystal structure in the 250-kelvin superconducting lanthanum hydride.

The discovery of superconductivity at 200 kelvin in the hydrogen sulfide system at high pressures1 demonstrated the potential of hydrogen-rich materials as high-temperature superconductors. Recent theoretical predictions of rare-earth hydrides with hydrogen cages2,3 and the subsequent synthesis of LaH10 with a superconducting critical temperature (Tc) of 250 kelvin4,5 have placed these materials on the verge of achieving the long-standing goal of room-temperature superconductivity. Electrical and X-ray diffraction measurements have revealed a weakly pressure-dependent Tc for LaH10 between 137 and 218 gigapascals in a structure that has a face-centred cubic arrangement of lanthanum atoms5. Here we show that quantum atomic fluctuations stabilize a highly symmetrical [Formula: see text] crystal structure over this pressure range. The structure is consistent with experimental findings and has a very large electron-phonon coupling constant of 3.5. Although ab initio classical calculations predict that this [Formula: see text] structure undergoes distortion at pressures below 230 gigapascals2,3, yielding a complex energy landscape, the inclusion of quantum effects suggests that it is the true ground-state structure. The agreement between the calculated and experimental Tc values further indicates that this phase is responsible for the superconductivity observed at 250 kelvin. The relevance of quantum fluctuations calls into question many of the crystal structure predictions that have been made for hydrides within a classical approach and that currently guide the experimental quest for room-temperature superconductivity6-8. Furthermore, we find that quantum effects are crucial for the stabilization of solids with high electron-phonon coupling constants that could otherwise be destabilized by the large electron-phonon interaction9, thus reducing the pressures required for their synthesis.

Fitness for working in a policeman being treated for OSAS.

A policeman who has been ill with OSAS for 10 years is in optimal CPAP therapy. During this time, the overall assessment of his work activities was excellent and he had no traffic accidents or accidents at work. Concerning his work as a policeman, the Medical Commission of 1st instance considered him unfit to work. Conversely, the Medical Commission of 2nd instance declared him fit to work. In the adult general population, the prevalence of moderate and severe OSAS is more than 20%. It is therefore likely that there are many policemen affected by OSAS and the number of requests for assessments of fitness to work in those with OSAS will increase. It is a priority: (i) to integrate the training course of the medical staff of the Police Forces and the Armed Forces with updates on OSAS; (ii) to delete OSAS from the list of chronic diseases for which night shift work is not indicated.

Direct evaluation of the isotope effect within the framework of density functional theory for superconductors.

Within recent developments of density functional theory, its numerical implementation and of the superconducting density functional theory is nowadays possible to predict the superconducting critical temperature, [Formula: see text], with sufficient accuracy to anticipate the experimental verification. In this paper we present an analytical derivation of the isotope coefficient within the superconducting density functional theory. We calculate the partial derivative of [Formula: see text] with respect to atomic masses. We verified the final expression by means of numerical calculations of isotope coefficient in monatomic superconductors (Pb) as well as polyatomic superconductors (CaC6). The results confirm the validity of the analytical derivation with respect to the finite difference methods, with considerable improvement in terms of computational time and calculation accuracy. Once the critical temperature is calculated (at the reference mass(es)), various isotope exponents can be simply obtained in the same run. In addition, we provide the expression of interesting quantities like partial derivatives of the deformation potential, phonon frequencies and eigenvectors with respect to atomic masses, which can be useful for other derivations and applications.

Obstructive Sleep Apnea Syndrome (OSAS): Continuous Positive Airway Pressure (CPAP) therapy and other positive-pressure devices. / Sindrome delle Apnee Ostruttive nel Sonno (OSAAS): la terapia con pressione positive continua nelle vie aeree (CPAP) ed altri dispositive a pressione positive.

The Obstructive Sleep Apnea Syndrome (OSAS) consists of recurring episodes of complete or partial obstruction of the pharynx. The application of a continuous positive pressure in the airways (CPAP) is the first therapeutic option that is found to ensure complete patency of the pharynx during sleep, avoiding apneas and hypopneas with resolution of the symptoms. More recently, other devices have been proposed as OSAS treatment. The auto-CPAP has a role in finding the therapeutic value of the CPAP pressure rather than in OSAS therapy. When apnea/hypopnea events are associated with other and/or predominant respiratory disorders like hypoventilation or Cheyne-Stokes breathing, the treatment of choice is the noninvasive ventilation with a double level of pressure support. Although it was proposed 35 years ago, the CPAP still represents the only effective therapy regardless of OSAS severity, as well as the treatment with the greatest evidence in terms of long-term benefits.

Obstructive sleep apnea (OSA): healthcare and social costs. / La Sindrome dell 'Apnea Ostruttiva nel sonno (OSAS): I costi sanitari e sociali.

Obstructive sleep apnea (OSA) syndrome is an underdiagnosed widespread chronic disease involving both sexes and all ages. Undiagnosed and untreated OSA is associated with workplace productivity losses and significant direct and indirect medical costs. A cost analysis of OSA was carried out in Italy ten years ago. Overall OSA medical costs, largely due to treatment of comorbidity, amounted to € 2,9 billion or 55% of total medical costs. Direct medical costs, due to diagnosis and treatment of OSA, were 6% of overall OSA costs, while medical costs due to the absence of diagnosis and of prevention of comorbidities represented 49% of the overall cost. Non-medical costs made up for the remaining 45%. € 1.5 billion could be saved by promoting screening campaigns aimed at detecting OSA that would otherwise remain undiagnosed and by improving adherence to treatment. Bearing in mind the increasing OSA prevalence and the recent quantification of avoidable OSA-related road accidents, the real cost of OSA is higher than estimated up to now.

Emergence of superconductivity in doped H2O ice at high pressure.

We investigate the possibility of achieving high-temperature superconductivity in hydrides under pressure by inducing metallization of otherwise insulating phases through doping, a path previously used to render standard semiconductors superconducting at ambient pressure. Following this idea, we study H2O, one of the most abundant and well-studied substances, we identify nitrogen as the most likely and promising substitution/dopant. We show that for realistic levels of doping of a few percent, the phase X of ice becomes superconducting with a critical temperature of about 60 K at 150 GPa. In view of the vast number of hydrides that are strongly covalent bonded, but that remain insulating up to rather large pressures, our results open a series of new possibilities in the quest for novel high-temperature superconductors.

Risk of Occupational Accidents in Workers with Obstructive Sleep Apnea: Systematic Review and Meta-analysis.

STUDY OBJECTIVES: Obstructive sleep apnea (OSA) is the single most important preventable medical cause of excessive daytime sleepiness (EDS) and driving accidents. OSA may also adversely affect work performance through a decrease in productivity, and an increase in the injury rate. Nevertheless, no systematic review and meta-analysis of the relationship between OSA and work accidents has been performed thus far. METHODS: PubMed, PsycInfo, Scopus, Web of Science, and Cochrane Library were searched. Out of an initial list of 1,099 papers, 10 studies (12,553 participants) were eligible for our review, and 7 of them were included in the meta-analysis. The overall effects were measured by odds ratios (OR) and 95% confidence intervals (CI). An assessment was made of the methodological quality of the studies. Moderator analysis and funnel plot analysis were used to explore the sources of between-study heterogeneity. RESULTS: Compared to controls, the odds of work accident was found to be nearly double in workers with OSA (OR = 2.18; 95% CI = 1.53-3.10). Occupational driving was associated with a higher effect size. CONCLUSIONS: OSA is an underdiagnosed nonoccupational disease that has a strong adverse effect on work accidents. The nearly twofold increased odds of work accidents in subjects with OSA calls for workplace screening in selected safety-sensitive occupations. COMMENTARY: A commentary on this article appears in this issue on page 1171.

Motor vehicle accidents and obstructive sleep apnea syndrome: A methodology to calculate the related burden of injuries.

The association between motor vehicle accidents (MVAs) and obstructive sleep apnea syndrome (OSAS) has always been quantified as risk of MVAs for individual drivers with OSAS. We evaluated the expected injured patients per year attributable to OSAS-dependent MVAs in a general population. By combining OSAS prevalence and OSAS-dependent MVAs odds ratio, we assessed the population attributable fraction (PAF), an epidemiological tool that can be used to quantify the proportion of road traffic injuries (RTIs) attributable to OSAS. For an apnea hypopnea index >5, the weighed median and combined average of OSAS prevalence were 4.4 (95% confidence interval (CI): 3.7-7.5) and 4.7 (95% CI: 4.2-5.2), respectively; values of risk of OSAS-dependent MVAs were 2.83 (95% CI: 2.72-3.08) and 2.52 (95% CI: 2.07-3.08), respectively. The PAF showed weighed median and combined average values of 6.6 (95% CI: 4.3-9.8) and 7.3% (95% CI: 6.0-13.5), respectively. Our results show that about 7% of RTIs for a population of male drivers involved in MVAs are attributable to OSAS. This value can be used to assess the potential impact, on the reduction of incidence of the motor vehicle injuries, of prevention programs aimed at reducing the number of subjects with an undiagnosed and/or untreated OSAS.