Photocatalytic conversion of nitrogen to ammonia is a green alternative for the Haber-Bosch process. The current progress in photocatalytic nitrogen reduction suggests, however, that there exists a ...large gap in performance before commercial use is viable. One of the major challenges is that no highly active photocatalysts exist. Furthermore, the development of photocatalysts is greatly hindered by false positives or non-reproducible data. Here, we will describe the current known causes of non-reproducible results in the literature and present solutions to mitigate these false positive results. Finally, we highlight the main challenges that remain for photocatalytic nitrogen fixation. We aim to help researchers design more reliable experiments and inspire practical research in developing photocatalytic ammonia synthesis.The development of photocatalysts is greatly hindered by false positives or non-reproducible data. Here, The authors describe the current known causes of non-reproducible results in the literature and present solutions to mitigate these false positive results.
Real-time reverse transcription-PCR (RT-PCR) is currently the most sensitive method to detect severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) that causes coronavirus disease 2019 ...(COVID-19). However, the correlation between detectable viral RNA and culturable virus in clinical specimens remains unclear. Here, we performed virus culture for 60 specimens that were confirmed to be positive for SARS-CoV-2 RNA by real-time RT-PCR. The virus could be successfully isolated from 12 throat and nine nasopharyngeal swabs and two sputum specimens. The lowest copy number required for virus isolation was determined to be 5.4, 6.0, and 5.7 log
genome copies/ml sample for detecting the
,
, and
genes, respectively. We further examined the correlation of genome copy number and virus isolation in different regions of the viral genome, demonstrating that culturable specimens are characterized by high copy numbers with a linear correlation observed between copy numbers of amplicons targeting structural and nonstructural regions. Overall, these results indicate that in addition to the copy number, the integrity of the viral genome should be considered when evaluating the infectivity of clinical SARS-CoV-2 specimens.
Zinc–bromine flow batteries are promising for stationary energy storage, and bromine‐complexing agents have been used to form phase‐separated liquid polybromide products. However, an understanding of ...the dynamics of polybromide nucleation is limited due to the beam sensitivity and complexity of polybromides. Here we report an in operando platform composed of dark‐field light microscopy and a transparent electrochemical cell to reveal the dynamics of polybromide formation in their native environment. Using our platform, we confirm and reveal the liquid nature, chemical composition, pinning effect (strong interaction with Pt), residual effect (residual charge products on the surface), self‐discharging, and over‐oxidation of the polybromide products. The results provide insights into the role of complexing agents and guide the future design of zinc–bromine flow batteries. Furthermore, our in operando platform can potentially be used to study sensitive species and phases in other electrochemical reactions.
Drop me a line: Using dark‐field light microscopy and a transparent electrochemical cell, the electrochemical nucleation and formation of polybromides on a Pt surface is visualized. Raman spectroscopy and DFT calculations give further insight into the underlying reaction mechanisms. The approach allows to diagnose zinc–bromine flow batteries.
Taiwan experienced two waves of imported infections with Coronavirus Disease 2019 (COVID-19). This study aimed at investigating the genomic variation of severe acute respiratory syndrome coronavirus ...2 (SARS-CoV-2) in Taiwan and compared their evolutionary trajectories with the global strains. We performed culture and full-genome sequencing of SARS-CoV-2 strains followed by phylogenetic analysis. A 382-nucleotides deletion in open reading frame 8 (ORF8) was found in a Taiwanese strain isolated from a patient on February 4, 2020 who had a travel history to Wuhan. Patients in the first wave also included several sporadic, local transmission cases. Genomes of 5 strains sequenced from clustered infections were classified into a new clade with ORF1ab-V378I mutation, in addition to 3 dominant clades ORF8-L84S, ORF3a-G251V and S-D614G. This highlighted clade also included some strains isolated from patients who had a travel history to Turkey and Iran. The second wave mostly resulted from patients who had a travel history to Europe and Americas. All Taiwanese viruses were classified into various clades. Genomic surveillance of SARS-CoV-2 in Taiwan revealed a new ORF8-deletion mutant and a virus clade that may be associated with infections in the Middle East, which contributed to a better understanding of the global SARS-CoV-2 transmission dynamics.
Electrochemical nitrate reduction reaction (NO3RR) has garnered increasing attention as a pathway for converting a harmful pollutant (nitrate) into a value‐added product (ammonia). However, high ...selectivity toward ammonia (NH3) is imperative for process viability. Optimizing proton availability near the catalyst is important for achieving selective NH3 production. Here, the aim is to systematically examine the impacts of proton availability on NO3RR selectivity in a bipolar membrane (BPM)‐based membrane electrode assembly (MEA) system. The BPM generates a proton flux from the membrane toward the catalyst during electrolysis. Thus, the BPM‐MEA system can modulate the proton flux during operation. The impact of interposer layers, proton scavenging electrolytes (CO32−), and catalyst configurations are also examined to identify which local microenvironments favor ammonia formation. It is found that a moderate proton supply allows for an increase in ammonia yield by 576% when compared to the standard MEA setup. This also results in a high selectivity of 26 (NH3 over NO2−) at an applied current density of 200 mA cm−2.
High selectivity toward ammonia is vital for the feasibility of the electrochemical nitrate reduction reaction (NO3RR). This study employs a bipolar membrane‐based membrane electrode assembly system to investigate the influence of proton availability on the selectivity of NO3RR. The results underscore the pivotal importance of moderate proton supply for achieving highly selective NH3 production in NO3RR.
Atrial fibrillation (AF) is often asymptomatic and paroxysmal. Screening and monitoring are needed especially for people at high risk. This study sought to use camera-based remote ...photoplethysmography (rPPG) with a deep convolutional neural network (DCNN) learning model for AF detection. All participants were classified into groups of AF, normal sinus rhythm (NSR) and other abnormality based on 12-lead ECG. They then underwent facial video recording for 10 min with rPPG signals extracted and segmented into 30-s clips as inputs of the training of DCNN models. Using voting algorithm, the participant would be predicted as AF if > 50% of their rPPG segments were determined as AF rhythm by the model. Of the 453 participants (mean age, 69.3 ± 13.0 years, women, 46%), a total of 7320 segments (1969 AF, 1604 NSR & 3747others) were analyzed by DCNN models. The accuracy rate of rPPG with deep learning model for discriminating AF from NSR and other abnormalities was 90.0% and 97.1% in 30-s and 10-min recording, respectively. This contactless, camera-based rPPG technique with a deep-learning model achieved significantly high accuracy to discriminate AF from non-AF and may enable a feasible way for a large-scale screening or monitoring in the future.
We model hydrothermal convection using a partial differential equation formed by Darcy velocity and temperature—the velocity formulation. Using the Elder problem as a benchmark, we found that the ...velocity formulation is a valid model of hydrothermal convection. By performing simulations with Rayleigh numbers in the non-oscillatory regime, we show that multiple quasi-steady-state solutions can be one of the reasons that caused the Nusselt–Rayleigh discrepancy found in previous experiments. The results reveal more understandings about the nature of uncertainty of convection modes in porous media.
The extraction yield, total phenols, caffeic acid derivatives (CAD), and antioxidant properties of 50% ethanolic Echinacea purpurea flower extract were determined. The in vitro inhibitory effects of ...50% ethanolic extract and CAD on α-amylase, α-glucosidase, and angiotensin-converting enzyme (ACE) linked with type 2 diabetes were also investigated. The extraction yield, total phenols, and total CAD of the extract were 27.04%, 195.69 mg CAE/g and 78.42 mg/g, respectively. Cichoric acid (56.03 mg/g) was the predominant CAD compound in the extract. The extract exhibited good antioxidant properties. The extract and CAD inhibited α-amylase, α-glucosidase, and ACE activities in a concentration-dependent manner. Among the tested samples, chlorogenic acid, and caffeic acid (IC
of 1.71-1.81 mg/mL) had the highest α-amylase inhibitory activity, cichoric acid (IC
of 0.28 mg/mL) showed higher α-glucosidase inhibitory activity. Both chlorogenic acid and caffeic acid (IC
of 0.11-0.14 mg/mL) demonstrated higher ACE-inhibitory activity. The in vitro results suggest that E. purpurea extract and CAD have good potential for managing hyperglycemia and hypertension. Overall, the data suggest it is a choice for developing antihyperglycemia and antihypertension compounds from field-grown E. purpurea.
This article aims to implement an axial flux variable reluctance (VR) resolver design with a three-dimensional unequal air gap rotor via the newly developed magnetic metal additive manufacturing ...method, also known as Selective Laser Melting (SLM). Under the same eccentricity, the proposed axial flux VR possesses a smaller sensing angle error, having an improved eccentric fault tolerance higher than that of the radial type. Consequently, the proposed axial flux VR can greatly reduce the process precision requirement and benefit mass production. In this work, finite element analysis was utilized to simulate and verify the resolver. SLM technology was combined with oxygen control technology to reduce the eddy current loss of the resolver, which can quickly and accurately fabricate the three-dimensional parts of the resolver stator and rotor without mold-making. Finally, the experimental results with the axial flux VR resolver prototype are presented to verify the designed performance and compared with the commercial radial flux variable reluctance resolver.
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