Quantum ESPRESSO: a modular and open-source software project for quantum simulations of materials

Quantum ESPRESSO is an integrated suite of computer codes for electronic-structure calculations and materials modeling, based on density-functional theory, plane waves, and pseudopotentials (norm-conserving, ultrasoft, and projector-augmented wave). Quantum ESPRESSO stands for "opEn Source Package for Research in Electronic Structure, Simulation, and Optimization". It is freely available to researchers around the world under the terms of the GNU General Public License. Quantum ESPRESSO builds upon newly-restructured electronic-structure codes that have been developed and tested by some of the original authors of novel electronic-structure algorithms and applied in the last twenty years by some of the leading materials modeling groups worldwide. Innovation and efficiency are still its main focus, with special attention paid to massively-parallel architectures, and a great effort being devoted to user friendliness. Quantum ESPRESSO is evolving towards a distribution of independent and inter-operable codes in the spirit of an open-source project, where researchers active in the field of electronic-structure calculations are encouraged to participate in the project by contributing their own codes or by implementing their own ideas into existing codes.Comment: 36 pages, 5 figures, resubmitted to J.Phys.: Condens. Matte

Chemisorption sites and reaction pathways for acetylene on Si(111)-(7x7)

The interaction between the acetylene molecule (C2H2) and the Si(1 1 1)-(7 x 7) surface is studied using both ab initio and empirical methods. Several possible chemisorption configurations are explored, which may be helpful to rationalize recent experimental results. The kinetics of the chemisorption process is also studied by means of accurate ab initio calculations, and low-energy paths leading to stable configurations are identified. It is shown that large-scale calculations based on the use of semi-empirical potentials, in tight cooperation with ab initio calculations, can be an efficient tool to achieve a broad overview of the chemisorption reactions of molecules occurring on complex semiconductor surfaces

Acetylene on Si(111) from computer simulations

The interaction between the acetylene molecule (C_2H_2) and the Si(111)-(7 x 7) surface is studied with the combined use of ab initio and empirical methods. Several possible chemisorption configurations are explored, which may be helpful to rationalize recent experimental results. The kinetics of the chemisorption process can be described by identifying the low-energy paths between pairs of stable configurations. This can be done by means of accurate ab initio calculations only for small-scale models of surface reconstructions. It is shown that large-scale calculations based on the use of semi-empirical potentials, validated by ab initio calculations for small-scale models, can be an efficient tool to study chemisorption reactions of molecules occurring on complex semiconductor surfaces

Ab initio investigation of the adsorption of organic molecules at Si(111) and Si(100) surfaces

I To investigate the early stages of SiC growth on silicon, we performed an ab initio study of the adsorption of C2H2 and other small organic molecules on different Si surfaces. Our calculations, based both on geometry optimization and on finite-temperature molecular dynamics simulations, show that for all the molecules that we have considered the preferred adsorption sites at low temperature are confined at the surface, with no sub-surface penetration. Adsorption occurs through the formation of Si-C bonds, accompanied by a distortion of the adsorbed molecule to adapt the Si-C distance to the SiC bulk bond length. We discuss similarities and differences upon changing the organic molecule and the crystal face. To complete the study with the computation of directly measurable quantities, we analyze the optical reflectance anisotropy of one simulated structure. (C) 2003 Elsevier Science B.V. All rights reserved

The three facets of the SARS-CoV-2 pandemic during the first two waves in the northern, central, and southern Italy

Background: There is a scarcity of information in literature regarding the clinical differences and comorbidities of patients affected by Coronavirus disease 2019 (COVID-19), which could clarify the different prevalence of the outcomes (composite and only death) between several Italian regions. Objective: This study aimed to assess the heterogeneity of clinical features of patients with COVID-19 upon hospital admission and disease outcomes in the northern, central, and southern Italian regions. Methods: An observational cohort multicenter retrospective study including 1210 patients who were admitted for COVID-19 in Infectious diseases, Pulmonology, Endocrinology, Geriatrics and Internal Medicine Units in Italian cities stratified between north (263 patients); center (320 patients); and south (627 patients), during the first and second pandemic waves of SARS-CoV-2 (from February 1, 2020 to January 31, 2021). The data, obtained from clinical charts and collected in a single database, comprehended demographic characteristics, comorbidities, hospital and home pharmacological therapies, oxygen therapy, laboratory values, discharge, death and Intensive care Unit (ICU) transfer. Death or ICU transfer were defined as composite outcomes. Results: Male patients were more frequent in the northern Italian region than in the central and southern regions. Diabetes mellitus, arterial hypertension, chronic pulmonary and chronic kidney diseases were the comorbidities more frequent in the southern region; cancer, heart failure, stroke and atrial fibrillation were more frequent in the central region. The prevalence of the composite outcome was recorded more frequently in the southern region. Multivariable analysis showed a direct association between the combined event and age, ischemic cardiac disease, and chronic kidney disease, in addition to the geographical area. Conclusions: Statistically significant heterogeneity was observed in patients with COVID-19 characteristics at admission and outcomes from northern to southern Italy. The higher frequency of ICU transfer and death in the southern region may depend on the wider hospital admission of frail patients for the availability of more beds since the burden of COVID-19 on the healthcare system was less intense in southern region. In any case, predictive analysis of clinical outcomes should consider that the geographical differences that may reflect clinical differences in patient characteristics, are also related to access to health-care facilities and care modalities. Overall, the present results caution against generalizability of prognostic scores in COVID-19 patients derived from hospital cohorts in different settings

Exposure to artificial light at night: A common link for obesity and cancer?

Exposure to artificial light at night (ALAN) has been associated with disruption of the circadian system, which has been pointed out to have detrimental effects on health. Exposure to outdoor ALAN is very frequent in industrialised countries due to nocturnal light pollution and the relevant involvement of the total workforce in shift work and night work. Ecological and epidemiologic studies highlight the association between exposure to ALAN and several diseases, mainly obesity and cancer. More recently, also indoor ALAN exposure has been investigated. Among several multifactorial mechanisms linking ALAN exposure and health risks, suppression of melatonin secretion plays a pivotal role leading to alterations in circadian rhythm patterns, that are detrimental in terms of appetite regulation, and dysfunctions in metabolic signalling and cell growth in cancer. In addition, gut dysbiosis, inflammation, hypovitaminosis D, imbalance in cytokine secretion and levels are responsible for the multiple relationship linking circadian dysregulation due to ALAN exposure and obesity, and cancer. Therefore, the current manuscript summarises human and basic studies pointing out the impact of ALAN exposure on health, mostly focusing on obesity and cancer. Based on extant evidence, prevention strategies for obesity and cancer should be prompted, targeting exposure to ALAN. (C) 2022 Published by Elsevier Ltd

Correction: Advice of General Practitioner, of Surgeon, of Endocrinologist, and Self-Determination: the Italian Road to Bariatric Surgery

Purpose Bariatric surgery (BS) is considered the most efcient treatment for severe obesity. International guidelines recommend multidisciplinary approach to BS (general practitioners, endocrinologists, surgeons, psychologists, or psychiatrists), and access to BS should be the fnal part of a protocol of treatment of obesity. However, there are indications that general practitioners (GPs) are not fully aware of the possible benefts of BS, that specialty physicians are reluctant to refer their patients to surgeons, and that patients with obesity choose self-management of their own obesity, including internet-based choices. There are no data on the pathways chosen by physicians and patients to undergo BS in the real world in Italy. Methods An exploratory exam was performed for 6 months in three pilot regions (Lombardy, Lazio, Campania) in twentythree tertiary centers for the treatment of morbid obesity, to describe the real pathways to BS in Italy. Results Charts of 2686 patients (788 men and 1895 women, 75.5% in the age range 30–59 years) were evaluated by physicians and surgeons of the participating centers. A chronic condition of obesity was evident for the majority of patients, as indicated by duration of obesity, by presence of several associated medical problems, and by frequency of previous dietary attempts to weight loss. The vast majority (75.8%) patients were self-presenting or referred by bariatric surgeons, 24.2% patients referred by GPs and other specialists. Self-presenting patients were younger, more educated, more professional, and more mobile than patients referred by other physicians. Patients above the age of 40 years or with a duration of obesity greater than 10 years had a higher prevalence of all associated medical problems. Conclusions The majority of patients referred to a tertiary center for the treatment of morbid obesity have a valid indication for BS. Most patients self-refer to the centers, with a minority referred by a GP or by specialists. Self-presenting patient