Kinetics and Mechanism of Metal Nanoparticle Growth via Optical Extinction Spectroscopy and Computational Modeling: The Curious Case of Colloidal Gold

An overarching computational framework unifying several optical theories to describe the temporal evolution of gold nanoparticles (GNPs) during a seeded growth process is presented. To achieve this, we used the inexpensive and widely available optical extinction spectroscopy, to obtain quantitative kinetic data. In situ spectra collected over a wide set of experimental conditions were regressed using the physical model, calculating light extinction by ensembles of GNPs during the growth process. This model provides temporal information on the size, shape, and concentration of the particles and any electromagnetic interactions between them. Consequently, we were able to describe the mechanism of GNP growth and divide the process into distinct genesis periods. We provide explanations for several longstanding mysteries, for example, the phenomena responsible for the purple-greyish hue during the early stages of GNP growth, the complex interactions between nucleation, growth, and aggregation events, and a clear distinction between agglomeration and electromagnetic interactions. The presented theoretical formalism has been developed in a generic fashion so that it can readily be adapted to other nanoparticulate formation scenarios such as the genesis of various metal nanoparticles.Comment: Main text and supplementary information (accompanying MATLAB codes available on the journal webpage

Global uncertainty-sensitivity analysis on mechanistic kinetic models: From model assessment to theory-driven design of nanoparticles

Recently, we developed a population balance framework describing the precipitation of calcium-silicate-hydrate, a key nanomaterial in the construction industry and with potential applications in biomedicine, environmental remediation, and catalysis. In this article, we first refine our computational workflow by developing a more efficient and robust method for the solution of the moment-transformed population balance equations. Then, we generalize our framework by coupling to PHREEQC, a widely used opensource speciation solver, to enhance the adaptability of the framework to new systems. Using this improved computational model, we perform global uncertainty/sensitivity analysis (UA/SA) to understand the effect of variations in the model parameters and experimental conditions on the properties of the product. With the specific surface area of particles as an example, we show that UA/SA identifies the factors whose control would allow a fine-tuning of the desired properties. This general approach can be transferred to other nanoparticle synthesis schemes as well. (C) 2020 The Authors. Published by Elsevier Ltd

Regular physical activity postpones age of occurrence of first-ever stroke and improves long-term outcomes

Objective: Few data are available on the associations between the level of pre-stroke physical activity and long-term outcomes in patients with stroke. This study is designed to assess the associations between pre-stroke physical activity and age of first-ever stroke occurrence and long-term outcomes. Methods: Six hundred twenty-four cases with first-ever stroke were recruited from the Mashhad Stroke Incidence Study a prospective population-based cohort in Iran. Data on Physical Activity Level (PAL) were collected retrospectively and were available in 395 cases. According to the PAL values, subjects were classified as inactive (PAL \u3c 1.70) and active (PAL ≥ 1.70). Age at onset of stroke was compared between active and inactive groups. Using logistic model, we assessed association between pre-stroke physical activity and long-term (5-year) mortality, recurrence, disability, and functional dependency rates. We used multiple imputation to analyze missing data. Results: Inactive patients (PAL \u3c 1.70) were more than 6 years younger at their age of first-ever-stroke occurrence (60.7 ± 15.5) than active patients (67.0 ± 13.2; p \u3c 0.001). Patients with PAL\u3c 1.7 also had a greater risk of mortality at 1 year [adjusted odds ratio (aOR) = 2.31; 95%CI: 1.14–4.67, p = 0.02] and 5 years after stroke (aOR = 1.81; 95%CI: 1.05–3.14, p = 0.03) than patients who were more physically active. Recurrence rate, disability, and functional dependency were not statistically different between two groups. Missing data analysis also showed a higher odds of death at one and 5 years for inactive patients. Conclusions: In our cohort, we observed a younger age of stroke and a higher odds of 1- and 5-year mortality among those with less physical activity. This is an important health promotion strategy to encourage people to remain physically active

Call to action: SARS-CoV-2 and CerebrovAscular DisordErs (CASCADE)

Background and purpose: The novel severe acute respiratory syndrome coronavirus 2 (SARS-Cov-2), now named coronavirus disease 2019 (COVID-19), may change the risk of stroke through an enhanced systemic inflammatory response, hypercoagulable state, and endothelial damage in the cerebrovascular system. Moreover, due to the current pandemic, some countries have prioritized health resources towards COVID-19 management, making it more challenging to appropriately care for other potentially disabling and fatal diseases such as stroke. The aim of this study is to identify and describe changes in stroke epidemiological trends before, during, and after the COVID-19 pandemic.Methods: This is an international, multicenter, hospital-based study on stroke incidence and outcomes during the COVID-19 pandemic. We will describe patterns in stroke management, stroke hospitalization rate, and stroke severity, subtype (ischemic/hemorrhagic), and outcomes (including in-hospital mortality) in 2020 during COVID-19 pandemic, comparing them with the corresponding data from 2018 and 2019, and subsequently 2021. We will also use an interrupted time series (ITS) analysis to assess the change in stroke hospitalization rates before, during, and after COVID-19, in each participating center.Conclusion: The proposed study will potentially enable us to better understand the changes in stroke care protocols, differential hospitalization rate, and severity of stroke, as it pertains to the COVID-19 pandemic. Ultimately, this will help guide clinical-based policies surrounding COVID-19 and other similar global pandemics to ensure that management of cerebrovascular comorbidity is appropriately prioritized during the global crisis. It will also guide public health guidelines for at-risk populations to reduce risks of complications from such comorbidities

Research data supporting: Continuous, stable and safe organometallic reactions in flow at room temperature assisted by deep eutectic solvents

The video data is related to the publication entitled “Continuous, stable and safe organometallic reactions in flow at room temperature assisted by deep eutectic solvents”. The supporting media contains: * Hydrodynamic studies using segmented flow between the DES or DES/aqueous phase and the organic phase containing the substrate. For further information please refer to the publication and the video. * NMR dat

Correlations between COVID-19 and burden of dementia: An ecological study and review of literature

Introduction: Current evidence on the association between COVID-19 and dementia is sparse. This study aims to investigate the associations between COVID-19 caseload and the burden of dementia. Methods: We gathered data regarding burden of dementia (disability-adjusted life years [DALYs] per 100,000), life expectancy, and healthy life expectancy (HALE) from the Global Burden of Disease (GBD) 2017 study. We obtained COVID-19 data from Our World in Data database. We analyzed the association of COVID-19 cases and deaths with the burden of dementia using Spearman\u27s rank correlation coefficient. Results: Globally, we found significant positive (p \u3c.001) correlations between life expectancy (r = 0.60), HALE (r = 0.58), and dementia DALYs (r = 0.46) with COVID-19 caseloads. Likewise, we found similar correlations between life expectancy (r = 0.60), HALE (r = 0.58) and dementia DALYs (r = 0.54) with COVID-19 mortality. Conclusion: Health policymakers should clarify a targeted model of disease surveillance in order to reduce the dual burden of dementia and COVID-19

Call to Action: SARS-CoV-2 and CerebrovAscular DisordErs (CASCADE)

Background and purpose: The novel severe acute respiratory syndrome coronavirus 2 (SARS-Cov-2), now named coronavirus disease 2019 (COVID-19), may change the risk of stroke through an enhanced systemic inflammatory response, hypercoagulable state, and endothelial damage in the cerebrovascular system. Moreover, due to the current pandemic, some countries have prioritized health resources towards COVID-19 management, making it more challenging to appropriately care for other potentially disabling and fatal diseases such as stroke. The aim of this study is to identify and describe changes in stroke epidemiological trends before, during, and after the COVID-19 pandemic. Methods: This is an international, multicenter, hospital-based study on stroke incidence and outcomes during the COVID-19 pandemic. We will describe patterns in stroke management, stroke hospitalization rate, and stroke severity, subtype (ischemic/hemorrhagic), and outcomes (including in-hospital mortality) in 2020 during COVID-19 pandemic, comparing them with the corresponding data from 2018 and 2019, and subsequently 2021. We will also use an interrupted time series (ITS) analysis to assess the change in stroke hospitalization rates before, during, and after COVID-19, in each participating center. Conclusion: The proposed study will potentially enable us to better understand the changes in stroke care protocols, differential hospitalization rate, and severity of stroke, as it pertains to the COVID-19 pandemic. Ultimately, this will help guide clinical-based policies surrounding COVID-19 and other similar global pandemics to ensure that management of cerebrovascular comorbidity is appropriately prioritized during the global crisis. It will also guide public health guidelines for at-risk populations to reduce risks of complications from such comorbidities

Call to Action: SARS-CoV-2 and Cerebrovascular DisordErs (CASCADE)

Background and purposeThe novel severe acute respiratory syndrome coronavirus 2 (SARS-Cov-2), now named coronavirus disease 2019 (COVID-19), may change the risk of stroke through an enhanced systemic inflammatory response, hypercoagulable state, and endothelial damage in the cerebrovascular system. Moreover, due to the current pandemic, some countries have prioritized health resources towards COVID-19 management, making it more challenging to appropriately care for other potentially disabling and fatal diseases such as stroke. The aim of this study is to identify and describe changes in stroke epidemiological trends before, during, and after the COVID-19 pandemic.MethodsThis is an international, multicenter, hospital-based study on stroke incidence and outcomes during the COVID-19 pandemic. We will describe patterns in stroke management, stroke hospitalization rate, and stroke severity, subtype (ischemic/hemorrhagic), and outcomes (including in-hospital mortality) in 2020 during COVID-19 pandemic, comparing them with the corresponding data from 2018 and 2019, and subsequently 2021. We will also use an interrupted time series (ITS) analysis to assess the change in stroke hospitalization rates before, during, and after COVID-19, in each participating center.ConclusionThe proposed study will potentially enable us to better understand the changes in stroke care protocols, differential hospitalization rate, and severity of stroke, as it pertains to the COVID-19 pandemic. Ultimately, this will help guide clinical-based policies surrounding COVID-19 and other similar global pandemics to ensure that management of cerebrovascular comorbidity is appropriately prioritized during the global crisis. It will also guide public health guidelines for at-risk populations to reduce risks of complications from such comorbidities