The flow physics of COVID-19 Mittal, Rajat; Ni, Rui; Seo, Jung-Hee
Journal of fluid mechanics,
07/2020, Letnik:
894
Journal Article
Recenzirano
Odprti dostop
Flow physics plays a key role in nearly every facet of the COVID-19 pandemic. This includes the generation and aerosolization of virus-laden respiratory droplets from a host, its airborne dispersion ...and deposition on surfaces, as well as the subsequent inhalation of these bioaerosols by unsuspecting recipients. Fluid dynamics is also key to preventative measures such as the use of face masks, hand washing, ventilation of indoor environments and even social distancing. This article summarizes what we know and, more importantly, what we need to learn about the science underlying these issues so that we are better prepared to tackle the next outbreak of COVID-19 or a similar disease.
Aims/hypothesis
The aim of this study was to quantify the relative contributions of increased insulin secretion rate (ISR) and decreased insulin clearance rate (ICR) in the compensatory ...hyperinsulinaemia characteristic of insulin-resistant individuals without diabetes.
Methods
Obese (BMI ≥30 kg/m
2
) individuals without diabetes (
n
= 91) were identified from a registry of volunteers. Volunteers underwent the following measurements: oral glucose tolerance; insulin resistance (steady-state plasma glucose SSPG concentration during the insulin suppression test IST); ISR (using the graded glucose infusion test GGIT); and ICR (using the IST and GGIT). Participants were stratified into tertiles based on SSPG concentration: SSPG-1(insulin-sensitive); SSPG-2 (intermediate); and SSPG-3 (insulin-resistant).
Results
There were no differences in BMI and waist circumference among the SSPG tertiles. Serum alanine aminotransferase concentrations were higher in the SSPG-2 and SSPG-3 groups compared with the SSPG-1 group (
p
= 0.02). Following an oral glucose challenge, there was a progressive increase in the total integrated insulin response from the most insulin-sensitive to the most insulin-resistant tertiles (
p
< 0.001). Following intravenous glucose, the SSPG-3 group had significantly greater integrated glucose (median interquartile range, 32.9 30.8–36.3 mmol/l × h) and insulin responses (1711 1476–2223 mmol/l × h) compared with the SSPG-1 group (30.3 28.8–32.9 mmol/l × h,
p
= 0.04, and 851 600–1057 pmol/l × h,
p
< 0.001, respectively). Furthermore, only the SSPG-3 group had significant changes in both ISR and ICR (
p
< 0.001). In the SSPG-2 group, only the ICR was significantly decreased compared with the SSPG-1 group. Therefore, ICR progressively declined during the IST with increasing insulin resistance (SSPG-1, 0.48 0.41–0.59; SSPG-2, 0.43 0.39–0.50; SSPG-3, 0.34 0.31–0.40).
Conclusions/interpretation
While both increases in ISR and decreases in ICR compensate for insulin resistance, decreases in ICR may provide the first adaptation to decreased insulin sensitivity.
Virtual Reality (VR) is increasingly used in health-related fields and interventions using VR have the potential to be powerful tools in patient management. The aim of this study was to synthesize ...the effects of VR interventions for people with mild cognitive impairment (MCI) or dementia.
Electronic databases were searched to identify studies that used an experimental design to investigate VR intervention outcomes for patients with MCI or dementia. Studies were excluded if the intervention did not focus on VR, if relevant quantitative outcomes were not reported, or if the intended study purpose was assessment or diagnosis. Data were extracted and analyzed from studies that met criteria. To synthesize the intervention effect sizes (ES), we used random effects models to accommodate heterogeneity in the main effect and sub-group analyses. To identify the potential reason for heterogeneity and compare ES according to the moderator variables, subgroup analyses were conducted based on study characteristics and intervention outcomes.
Data from eleven studies that met eligibility criteria were analyzed. VR intervention delivered to participants with MCI or dementia produced small to medium effects (ES = 0.29, CI = 0.16, 0.42). The ES for studies using semi-immersive technology (ES = 0.37, CI = 0.25, 0.49) was greater than the studies using full-immersive VR (ES = 0.03, CI = -0.14, 0.21). The results showed small-to-medium effects for VR interventions affecting key outcome variables such as cognition (ES = 0.42, CI = 0.24, 0.60) and physical fitness (ES = 0.41, CI = 0.16, 0.65).
VR interventions, particularly of the semi-immersive type, are useful for people with MCI or dementia. These results should contribute to the establishment of practical guidelines for VR interventions for patients with cognitive decline.
Although the electroconversion of carbon dioxide (CO2) into ethanol is considered to be one of the most promising ways of using CO2, the ethanol selectivity is less than 50% because of difficulties ...in designing an optimal catalyst that arise from the complicated pathways for the electroreduction of CO2 to ethanol. Several approaches including the fabrication of oxide‐derived structures, atomic surface control, and the Cu+/Cu interfaces have been primarily used to produce ethanol from CO2. Here, a combined structure with Cu+ and high‐facets as electrocatalysts is constructed by creating high‐facets of wrinkled Cu surrounded by Cu2O mesh patterns. Using chemical vapor deposition graphene growth procedures, the insufficiently grown graphene is used as an oxidation‐masking material, and the high‐facet wrinkled Cu is simultaneously generated during the graphene growth synthesis. The resulting electrocatalyst shows an ethanol selectivity of 43% at −0.8 V versus reversible hydrogen electrode, which is one of the highest ethanol selectivity values reported thus far. This is attributed to the role of Cu+ in enhancing CO binding strength, and the high‐facets, which favor C–C coupling and the ethanol pathway. This method for generating the combined structure can be widely applicable not only for electrochemical catalysts but also in various fields.
A combined structure with Cu+ and high‐facets is developed via insufficient graphene growth and a postoxidation process. The synthesized catalysts show high ethanol selectivity from the electrochemical CO2 reduction. The enhanced CO binding strength due to the introduction of Cu+ induces stable CO adsorption while maintaining high‐facet properties, resulting in a favorable CO–CO coupling reaction for C2 formation.
Deregulation of the cyclin D‐CDK4/6‐INK4‐RB pathway leading to uncontrolled cell proliferation, is frequently observed in breast cancer. Currently, three selective CDK4/6 inhibitors have been FDA ...approved: palbociclib, ribociclib and abemaciclib. Despite promising clinical outcomes, intrinsic or acquired resistance to CDK4/6 inhibitors has limited the success of these treatments; therefore, the development of various strategies to overcome this resistance is of great importance. We highlight the various mechanisms that are directly or indirectly responsible for resistance to CDK4/6 inhibitors, categorizing them into two broad groups; cell cycle‐specific mechanisms and cell cycle‐nonspecific mechanisms. Elucidation of the diverse mechanisms through which resistance to CDK4/6 inhibitors occurs, may aid in the design of novel therapeutic strategies to improve patient outcomes. This review summarizes the currently available knowledge regarding mechanisms of resistance to CDK4/6 inhibitors, and possible therapeutic strategies that may overcome this resistance as well.
Use of Cu and Cu+ is one of the most promising approaches for the production of C2 products by the electrocatalytic CO2 reduction reaction (CO2RR) because it can facilitate CO2 activation and CC ...dimerization. However, the selective electrosynthesis of C2+ products on Cu0Cu+ interfaces is critically limited due to the low electrocatalytic production of ethanol relative to ethylene. In this study, a novel porous Cu/Cu2O aerogel network is introduced to afford high ethanol productivity by the electrocatalytic CO2RR. The aerogel is synthesized by a simple chemical redox reaction of a precursor and a reducing agent. CO2RR results reveal that the Cu/Cu2O aerogel produces ethanol as the major product, exhibiting a Faradaic efficiency (FEEtOH) of 41.2% and a partial current density (JEtOH) of 32.55 mA cm−2 in an H‐cell reactor. This is the best electrosynthesis performance for ethanol production reported thus far. Electron microscopy and electrochemical analysis results reveal that this dramatic increase in the electrosynthesis performance for ethanol can be attributed to a large number of Cu0Cu+ interfaces and an increase of the local pH in the confined porous aerogel network structure with a high‐surface‐area.
A Cu/Cu2O interconnected porous aerogel network exhibits remarkably high selectivity and productivity in ethanol electrosynthesis from CO2 (41.2% and 32.55mA cm−2 in an H‐cell). This high performance arises from a large population of Cu0Cu+ interfaces in the confined porous structure with a high surface area. This aerogel electrocatalyst is thought to be an appealing model for the commercial electrosynthesis of ethanol from CO2.
Recent reports showing the favorable role of patent foramen ovale (PFO) closure in patients with cryptogenic stroke have raised the issue of selecting optimal candidates.
This study, DEFENSE-PFO ...(Device Closure Versus Medical Therapy for Cryptogenic Stroke Patients With High-Risk Patent Foramen Ovale), evaluated whether the benefits of PFO closure can be determined on the basis of the morphologic characteristics of the PFO, as evaluated by transesophageal echocardiography.
Patients with cryptogenic stroke and high-risk PFO were divided between a transcatheter PFO closure and a medication-only group. High-risk PFO included PFO with atrial septal aneurysm, hypermobility (phasic septal excursion into either atrium ≥10 mm), or PFO size (maximum separation of the septum primum from the secundum) ≥2 mm. The primary endpoint was a composite of stroke, vascular death, or Thrombolysis In Myocardial Infarction-defined major bleeding during 2 years of follow-up.
From September 2011 until October 2017, 120 patients (mean age: 51.8 years) underwent randomization. PFO size, frequency of septal aneurysm (13.3% vs. 8.3%; p = 0.56), and hypermobility (45.0% vs. 46.7%; p > 0.99) were similar between the groups. All PFO closures were successful. The primary endpoint occurred exclusively in the medication-only group (6 of 60 patients; 2-year event rate: 12.9% log-rank p = 0.013; 2-year rate of ischemic stroke: 10.5% p = 0.023). The events in the medication-only group included ischemic stroke (n = 5), cerebral hemorrhage (n = 1), Thrombolysis In Myocardial Infarction-defined major bleeding (n = 2), and transient ischemic attack (n = 1). Nonfatal procedural complications included development of atrial fibrillation (n = 2), pericardial effusion (n = 1), and pseudoaneurysm (n = 1).
PFO closure in patients with high-risk PFO characteristics resulted in a lower rate of the primary endpoint as well as stroke recurrence. (Device Closure Versus Medical Therapy for Cryptogenic Stroke Patients With High-Risk Patent Foramen Ovale DEFENSE-PFO; NCT01550588).
Purpose
The radial k‐space trajectory is a well‐established sampling trajectory used in conjunction with magnetic resonance imaging. However, the radial k‐space trajectory requires a large number of ...radial lines for high‐resolution reconstruction. Increasing the number of radial lines causes longer acquisition time, making it more difficult for routine clinical use. On the other hand, if we reduce the number of radial lines, streaking artifact patterns are unavoidable. To solve this problem, we propose a novel deep learning approach with domain adaptation to restore high‐resolution MR images from under‐sampled k‐space data.
Methods
The proposed deep network removes the streaking artifacts from the artifact corrupted images. To address the situation given the limited available data, we propose a domain adaptation scheme that employs a pre‐trained network using a large number of X‐ray computed tomography (CT) or synthesized radial MR datasets, which is then fine‐tuned with only a few radial MR datasets.
Results
The proposed method outperforms existing compressed sensing algorithms, such as the total variation and PR‐FOCUSS methods. In addition, the calculation time is several orders of magnitude faster than the total variation and PR‐FOCUSS methods. Moreover, we found that pre‐training using CT or MR data from similar organ data is more important than pre‐training using data from the same modality for different organ.
Conclusion
We demonstrate the possibility of a domain‐adaptation when only a limited amount of MR data is available. The proposed method surpasses the existing compressed sensing algorithms in terms of the image quality and computation time.
The development of a simple and cost‐effective method for fabricating ≈10 nm scale nanopatterns over large areas is an important issue, owing to the performance enhancement such patterning brings to ...various applications including sensors, semiconductors, and flexible transparent electrodes. Although nanoimprinting, extreme ultraviolet, electron beams, and scanning probe litho‐graphy are candidates for developing such nanopatterns, they are limited to complicated procedures with low throughput and high startup cost, which are difficult to use in various academic and industry fields. Recently, several easy and cost‐effective lithographic approaches have been reported to produce ≈10 nm scale patterns without defects over large areas. This includes a method of reducing the size using the narrow edge of a pattern, which has been attracting attention for the past several decades. More recently, secondary sputtering lithography using an ion‐bombardment technique was reported as a new method to create high‐resolution and high‐aspect‐ratio structures. Recent progress in simple and cost‐effective top‐down lithography for ≈10 nm scale nanopatterns via edge and secondary sputtering techniques is reviewed. The principles, technical advances, and applications are demonstrated. Finally, the future direction of edge and secondary sputtering lithography research toward issues to be resolved to broaden applications is discussed.
The development of a method for fabricating ≈10 nm‐scale nanopatterns over large areas is an important issue. Edge lithography allows for reduction of the size of patterns through a simple and cost‐effective method. More recently, secondary sputtering lithography using an ion bombardment has been reported as a new method. Research on the methodology of the processes and various applications are reviewed.
Achieving high sensitivity in solid-state gas sensors can allow the precise detection of chemical agents. In particular, detection of volatile organic compounds (VOCs) at the parts per billion (ppb) ...level is critical for the early diagnosis of diseases. To obtain high sensitivity, two requirements need to be simultaneously satisfied: (i) low electrical noise and (ii) strong signal, which existing sensor materials cannot meet. Here, we demonstrate that 2D metal carbide MXenes, which possess high metallic conductivity for low noise and a fully functionalized surface for a strong signal, greatly outperform the sensitivity of conventional semiconductor channel materials. Ti3C2Tx MXene gas sensors exhibited a very low limit of detection of 50-100 ppb for VOC gases at room temperature. Also, the extremely low noise led to a signal-to-noise ratio 2 orders of magnitude higher than that of other 2D materials, surpassing the best sensors known. Our results provide insight in utilizing highly functionalized metallic sensing channels for developing highly sensitive sensors.
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