Computational analysis of single rising bubbles influenced by soluble surfactant

This paper presents novel insights about the influence of soluble surfactants on bubble flows obtained by Direct Numerical Simulation (DNS). Surfactants are amphiphilic compounds which accumulate at fluid interfaces and significantly modify the respective interfacial properties, influencing also the overall dynamics of the flow. With the aid of DNS local quantities like the surfactant distribution on the bubble surface can be accessed for a better understanding of the physical phenomena occurring close to the interface. The core part of the physical model consists in the description of the surfactant transport in the bulk and on the deformable interface. The solution procedure is based on an Arbitrary Lagrangian-Eulerian (ALE) Interface-Tracking method. The existing methodology was enhanced to describe a wider range of physical phenomena. A subgrid-scale (SGS) model is employed in the cases where a fully resolved DNS for the species transport is not feasible due to high mesh resolution requirements and, therefore, high computational costs. After an exhaustive validation of the latest numerical developments, the DNS of single rising bubbles in contaminated solutions is compared to experimental results. The full velocity transients of the rising bubbles, especially the contaminated ones, are correctly reproduced by the DNS. The simulation results are then studied to gain a better understanding of the local bubble dynamics under the effect of soluble surfactant. One of the main insights is that the quasi-steady state of the rise velocity is reached without ad- and desorption being necessarily in local equilibrium

Computational Analysis of Fluid Interfaces Influenced by Soluble Surfactant

This work presents novel insights about the influence of soluble surfactants on rising bubbles obtained by direct numerical simulation (DNS). Surfactants are amphiphilic compounds which accumulate at fluid interfaces and significantly modify the respective interfacial properties, influencing also the overall dynamics of the flow. Since these interfaces are moving, continuously deforming and expanding, the local time-dependent interfacial coverage is the most relevant quantity. With the aid of DNS, local quantities, like the surfactant distribution on the bubble surface, can be accessed for a better understanding of the physical phenomena occurring close to the interface. However, the description and the simulation of such processes poses severe challenges. The core part of the physical model consists of the description of the surfactant transport in the bulk and on the deformable interface. The solution procedure is based on an arbitrary Lagrangian–Eulerian (ALE) interface-tracking method. The existing framework was enhanced to describe a wider range of physical phenomena. After a thorough validation of the latest numerical developments, the DNS of single rising bubbles in contaminated solutions is compared to experimental results. The full velocity transients of the rising bubbles, especially the contaminated ones, are correctly reproduced by the DNS. The simulation results are then studied to gain a better understanding of the local bubble dynamics under the effect of soluble surfactant. As an outlook, the mathematical and numerical models have been further extended to describe the influence of surfactant on the mass transfer from the bubble to the liquid phase. Two different models are studied; the first where the species and the surfactant transport are solved independently, and the second one where the hindrance effect of surfactant on mass transfer is taken into account. Preliminary simulation results are presented and discussed

The impact of the COVID-19 pandemic on people with neurological disorders: an urgent need to enhance the health care system's preparedness

The major ethical issue posed by the COVID 19 pandemic are discussed with special reference to the impact on acute and chronic neurological disorder

Conversion to secondary progressive multiple sclerosis: patient awareness and needs. results from an online survey in Italy and Germany

Background: Few studies have investigated the experiences of patients around the conversion to secondary progressive multiple sclerosis (SPMS). ManTra is a mixed-method, co-production research project conducted in Italy and Germany to develop an intervention for newly-diagnosed SPMS patients. In previous project actions, we identified the needs and experiences of patients converting to SPMS via literature review and qualitative research which involved key stakeholders.Aims: The online patient survey aimed to assess, on a larger and independent sample of recently-diagnosed SPMS patients: (a) the characteristics associated to patient awareness of SPMS conversion; (b) the experience of conversion; (c) importance and prioritization of the needs previously identified.Methods: Participants were consenting adults with SPMS since <= 5 years. The survey consisted of three sections: on general and clinical characteristics; on experience of SPMS diagnosis disclosure (aware participants only); and on importance and prioritization of 33 pre-specified needs.Results: Of 215 participants, those aware of their SPMS diagnosis were 57% in Italy vs. 77% in Germany (p = 0.004). In both countries, over 80% of aware participants received a SPMS diagnosis from the neurologist; satisfaction with SPMS disclosure was moderate to high. Nevertheless, 28-35% obtained second opinions, and 48-56% reported they did not receive any information on SPMS. Participants actively seeking further information were 63% in Germany vs. 31% in Italy (p < 0.001).Variables independently associated to patient awareness were geographic area (odds ratio, OR 0.32, 95% CI 0.13-0.78 for Central Italy; OR 0.21, 95% CI 0.08-0.58 for Southern Italy [vs. Germany]) and activity limitations (OR 7.80, 95% CI 1.47-41.37 for dependent vs. autonomous patients).All pre-specified needs were scored a lot or extremely important, and two prioritized needs were shared by Italian and German patients: "physiotherapy" and "active patient care involvement." The other two differed across countries: "an individualized health care plan" and "information on social rights and policies" in Italy, and "psychological support" and "cognitive rehabilitation" in Germany.Conclusions: Around 40% of SPMS patients were not aware of their disease form indicating a need to improve patient-physician communication. Physiotherapy and active patient care involvement were prioritized in both countries

Structured reporting for fibrosing lung disease: a model shared by radiologist and pulmonologist

Objectives: To apply the Delphi exercise with iterative involvement of radiologists and pulmonologists with the aim of defining a structured reporting template for high-resolution computed tomography (HRCT) of patients with fibrosing lung disease (FLD). Methods: The writing committee selected the HRCT criteria\ue2\u80\u94the Delphi items\ue2\u80\u94for rating from both radiology panelists (RP) and pulmonology panelists (PP). The Delphi items were first rated by RPs as \ue2\u80\u9cessential\ue2\u80\u9d, \ue2\u80\u9coptional\ue2\u80\u9d, or \ue2\u80\u9cnot relevant\ue2\u80\u9d. The items rated \ue2\u80\u9cessential\ue2\u80\u9d by < 80% of the RP were selected for the PP rating. The format of reporting was rated by both RP and PP. Results: A total of 42 RPs and 12 PPs participated to the survey. In both Delphi round 1 and 2, 10/27 (37.7%) items were rated \ue2\u80\u9cessential\ue2\u80\u9d by more than 80% of RP. The remaining 17/27 (63.3%) items were rated by the PP in round 3, with 2/17 items (11.7%) rated \ue2\u80\u9cessential\ue2\u80\u9d by the PP. PP proposed additional items for conclusion domain, which were rated by RPs in the fourth round. Poor consensus was observed for the format of reporting. Conclusions: This study provides a template for structured report of FLD that features essential items as agreed by expert thoracic radiologists and pulmonologists

Disease-Modifying Therapies and Coronavirus Disease 2019 Severity in Multiple Sclerosis

Objective: This study was undertaken to assess the impact of immunosuppressive and immunomodulatory therapies on the severity of coronavirus disease 2019 (COVID-19) in people with multiple sclerosis (PwMS). Methods: We retrospectively collected data of PwMS with suspected or confirmed COVID-19. All the patients had complete follow-up to death or recovery. Severe COVID-19 was defined by a 3-level variable: mild disease not requiring hospitalization versus pneumonia or hospitalization versus intensive care unit (ICU) admission or death. We evaluated baseline characteristics and MS therapies associated with severe COVID-19 by multivariate and propensity score (PS)-weighted ordinal logistic models. Sensitivity analyses were run to confirm the results. Results: Of 844 PwMS with suspected (n = 565) or confirmed (n = 279) COVID-19, 13 (1.54%) died; 11 of them were in a progressive MS phase, and 8 were without any therapy. Thirty-eight (4.5%) were admitted to an ICU; 99 (11.7%) had radiologically documented pneumonia; 96 (11.4%) were hospitalized. After adjusting for region, age, sex, progressive MS course, Expanded Disability Status Scale, disease duration, body mass index, comorbidities, and recent methylprednisolone use, therapy with an anti-CD20 agent (ocrelizumab or rituximab) was significantly associated (odds ratio [OR] = 2.37, 95% confidence interval [CI] = 1.18-4.74, p = 0.015) with increased risk of severe COVID-19. Recent use (<1 month) of methylprednisolone was also associated with a worse outcome (OR = 5.24, 95% CI = 2.20-12.53, p = 0.001). Results were confirmed by the PS-weighted analysis and by all the sensitivity analyses. Interpretation: This study showed an acceptable level of safety of therapies with a broad array of mechanisms of action. However, some specific elements of risk emerged. These will need to be considered while the COVID-19 pandemic persists

DMTs and Covid-19 severity in MS: a pooled analysis from Italy and France

We evaluated the effect of DMTs on Covid-19 severity in patients with MS, with a pooled-analysis of two large cohorts from Italy and France. The association of baseline characteristics and DMTs with Covid-19 severity was assessed by multivariate ordinal-logistic models and pooled by a fixed-effect meta-analysis. 1066 patients with MS from Italy and 721 from France were included. In the multivariate model, anti-CD20 therapies were significantly associated (OR = 2.05, 95%CI = 1.39–3.02, p < 0.001) with Covid-19 severity, whereas interferon indicated a decreased risk (OR = 0.42, 95%CI = 0.18–0.99, p = 0.047). This pooled-analysis confirms an increased risk of severe Covid-19 in patients on anti-CD20 therapies and supports the protective role of interferon