Xsorb: a software for identifying the most stable adsorption configuration and energy of a molecule on a crystal surface

Molecular adsorption is the first important step of many surface-mediated chemical processes, from catalysis to tribology. This phenomenon is controlled by physical/chemical interactions, which can be accurately described by first principles calculations. In recent years, several computational tools have been developed to study molecular adsorption based on high throughput/automatized approaches. However, these tools can sometimes be over-sophisticated for non-expert users. In this work, we present Xsorb, a Python-based code that automatically generates adsorption configurations, guides the user in the identification the most relevant ones, which are then fully optimized. The code relies on well-established Python libraries, and on an open source package for density functional theory calculations. We show the program capabilities through an example consisting of a hydrocarbon molecule, 1-hexene, adsorbed over the (110) surface of iron. The presented computational tool will help users, even non-expert, to easily identify the most stable adsorption configuration of complex molecules on substrates and obtain accurate adsorption geometries and energies

Prevalence and prevention of venous thromboembolism in patients with acute exacerbations of COPD

Abstract BACKGROUND: Little information exists on the prevalence and prevention of deep vein thrombosis (DVT) and pulmonary embolism (PE) in patients admitted for acute exacerbations of chronic obstructive pulmonary disease (COPD). OBJECTIVE: To review available literature, we performed a Medline search on papers published on this topic between 1966 and 2003. DATA SYNTHESIS: Pulmonary emboli have been frequently found (up to 30% of cases) in autoptic series that included patients who died from acute exacerbation of COPD, while the real incidence of PE during exacerbation has never been prospectively evaluated by large-scale clinical studies. Diagnosis of concomitant PE in these patients is often missed because symptoms of acute exacerbation of COPD may mimic PE, and non-invasive evaluation by pulmonary scintigraphy or CT scan is less specific. Even if not fatal, undetected and untreated PE may lead to long-term morbidity from pulmonary hypertension and predispose to recurrent venous thromboembolism (VTE). DVT of the lower extremities affects about 10% of patients with acute exacerbation of COPD at admission, but the rate is likely to be underestimated. The results of clinical trials conducted on general medical patients, including COPD patients, indicate that unfractionated heparin (UH) and low molecular weight heparin (LMWH) significantly reduce VTE rates. However, subgroup data on COPD patients are generally not available. In a single randomised, controlled trial specifically conducted on COPD patients, nadroparin reduced the rate of DVT from 28% to 15% without affecting mortality. CONCLUSIONS: Despite a substantial lack of consistent data, VTE appears as a major threat to patients admitted for acute exacerbation of COPD, and pharmacologic prophylaxis should be considered in all high risk situations. However, methodologically rigorous studies in this setting are still needed

Zerovalent Fe, Co and Ni nanoparticle toxicity evaluated on SKOV-3 and U87 cell lines

ABSTRACT:We have considered nanoparticles (NPs) of Fe, Co and Ni, three transition metals sharing similar chemical properties. NP dissolution, conducted by radioactive tracer method and inductively coupled plasmamass spectrometry, indicated that NiNPs and FeNPs released in the medium a much smaller amount of ions than that released by Co NPs. The two considered methodological approaches, however, gave comparable but not identical results. All NPs are readily internalized by the cells, but their quantity inside the cells is less than 5%. Cytotoxicity and gene expression experimentswere performed on SKOV-3 and U87 cells. In both cell lines, CoNPs and NiNPs were definitely more toxic than FeNPs. Real-time polymerase chain reaction experiments aimed to evaluatemodifications of the expression of genes involved in the cellular stress response (HSP70, MT2A), or susceptible to metal exposure (SDHB1 and MLL), or involved in specific cellular processes (caspase3, IQSEC1 and VMP1), gave different response patterns in the two cell lines. HSP70, for example, was highly upregulated by CoNPs and NiNPs, but only in SKOV-3 cell lines. Overall, this work underlines the difficulties in predicting NP toxicological properties based only on their chemical characteristics. We, consequently, think that, at this stage of our knowledge, biological effects induced by metal-based NPs should be examined on a case-by-case basis following studies on different in vitro models. Moreover, with the only exception of U87 exposed to Ni, our results suggest thatmetallic NPs have caused, on gene expression, similar effects to those caused by their cor- Q2 responding ions

Delphi consensus recommendations on how to provide cardiovascular rehabilitation in the COVID-19 era

Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2020. For permissions, please email: [email protected] Delphi consensus by 28 experts from the European Association of Preventive Cardiology (EAPC) provides initial recommendations on how cardiovascular rehabilitation (CR) facilities should modulate their activities in view of the ongoing coronavirus disease 2019 (COVID-19) pandemic. A total number of 150 statements were selected and graded by Likert scale [from -5 (strongly disagree) to +5 (strongly agree)], starting from six open-ended questions on (i) referral criteria, (ii) optimal timing and setting, (iii) core components, (iv) structure-based metrics, (v) process-based metrics, and (vi) quality indicators. Consensus was reached on 58 (39%) statements, 48 'for' and 10 'against' respectively, mainly in the field of referral, core components, and structure of CR activities, in a comprehensive way suitable for managing cardiac COVID-19 patients. Panelists oriented consensus towards maintaining usual activities on traditional patient groups referred to CR, without significant downgrading of intervention in case of COVID-19 as a comorbidity. Moreover, it has been suggested to consider COVID-19 patients as a referral group to CR per se when the viral disease is complicated by acute cardiovascular (CV) events; in these patients, the potential development of COVID-related CV sequelae, as well as of pulmonary arterial hypertension, needs to be focused. This framework might be used to orient organization and operational of CR programmes during the COVID-19 crisis.info:eu-repo/semantics/publishedVersio

Designing compounds for friction reduction: from software development to application in conjunction with experiments

The design of novel, environmentally friendly materials to reduce friction and wear is crucial to save energy and reduce CO2 emissions. To improve the effectiveness of such materials, a clear understanding of the interactions between lubricant additives and the surface at the atomistic level is paramount. To investigate the complex additive-surface interactions by means of ab initio calculations, this thesis introduces Xsorb, a user-friendly Python-based program for identifying the adsorption energy and geometry of complex molecules on crystalline (reconstructed) surfaces. Working in conjunction with a DFT code, it generates multiple adsorption configurations via symmetry operations, identifies the most representative ones through a fast pre-optimization, and finds the potential energy surface (PES) global minimum with a full structural optimization. Two test-cases employing 1-hexene adsorption on iron and diamond surfaces showed Xsorb's effectiveness in reducing computational workload. The program was then applied to the design of a new lubrication system, in a combined computational and experimental work with the University of Coimbra. Experiments demonstrated that chemical modifications in lubricant additives and substrates provide enhanced friction reduction through synergistic effects. The simultaneous inclusion of N-containing 2-(Dimethylamino)ethyl methacrylate and silicon dopants respectively in lauryl-methacrylate additives and diamond-like carbon coatings resulted in a significant reduction of friction, with the formation of a tribofilm. Ab initio calculations of molecular adsorption and a charge density analysis uncovered the key role of the N-Si interaction in enabling the chemisorption of the additive molecules, which constitutes the initial stage for the tribofilm formation. These results open the way to high throughput approaches for discovering the optimal additive/substrate modifications to achieve lower friction and wear

Effetti della radiazione ionizzante su cristalli singoli di perovskiti ibride

Le perovskiti ibride ad alogenuri organometallici presentano notevoli proprietà optoelettroniche, tali da renderle buoni candidati per numerose applicazioni pratiche, come la realizzazione di celle solari e di detector di raggi X. In questa tesi si sono studiati gli effetti dell'esposizione ai raggi X su monocristalli di perovskiti MAPbBr3 (metilammonio piombo tribromuro), analizzando la fotocorrente per diversi dose rate di radiazione incidente e per diversi bias di tensione applicata. Dalla fotocorrente è poi stata calcolata la sensitivity. L'obiettivo principale è infatti quello di valutare la variazione di sensitivity dopo assorbimenti prolungati di raggi X (100 Gy e 200 Gy di dose cumulativa). Ciò che si è osservato è stato un calo significativo sia della sensitivity che della fotocorrente passando da 0 Gy a 100 Gy, mentre da 100 Gy a 200 Gy non si è avuta ulteriore diminuzione. Il campione ha poi mostrato un notevole recovery della sensitivity dopo un giorno di riposo, segno di una buona radiation hardness. Si è infine notato che la diminuzione della fotocorrente a 100 Gy è determinata da un incremento della corrente di buio, non dalla diminuzione della corrente sotto raggi X. Ciò fa pensare a un fenomeno di cattura dei portatori di carica liberi da parte di livelli energetici profondi, che contribuiscono alla corrente di buio ma non a quella sotto raggi X