•Virus variants are represented by 4-letter sequence based on AA mutations on spike.•An n-distance algorithm in UPGMA is utilized to derive variant phylogenetic tree.•Discovering new strain involves ...union of mutated sites and randomly generated set X.•New macro-lineage of SARS-CoV-2 is predicted when X reaches a sufficient scale.•Demarcation values that differentiate between various macro-lineages are derived.
With the rapid evolution of SARS-CoV-2, the emergence of new strains is an intriguing question. This paper presents an evolutionary theory to analyze the mutations of the virus and identify the conditions that lead to the generation of new strains. We represent the virus variants using a 4-letter sequence based on amino acid mutations on the spike protein and employ an n-distance algorithm to derive a variant phylogenetic tree. We show that the theoretically-derived tree aligns with experimental data on virus evolution. Additionally, we propose an A-X model, utilizing the set of existing mutation sites (A) and a set of randomly generated sites (X), to calculate the emergence of new strains. Our findings demonstrate that a sufficient number of random iterations can predict the generation of new macro-lineages when the number of sites in X is large enough. These results provide a crucial theoretical basis for understanding the evolution of SARS-CoV-2.
Artificial photoresponsive nanochannels have attracted widespread attention because of their capacity to achieve ion transport through light modulation. Herein, a biosensor for ultrasensitive ...miRNA‐155 detection is devised based on molybdenum disulfide (MoS2) modified porous anodic aluminum oxide (AAO) photoresponsive nanochannels by atomic layer deposition (ALD). According to the optimized experimental results, when the cycles of ALD, the wavelength, and the power of the excitation laser are 70 cycles, 450 nm, and 80 mW, respectively, the most supreme photocurrent performance of these photoresponsive nanochannels are obtained. AAO nanochannels modified with MoS2 can work as a photoelectrochemical (PEC) biosensor by generating photoexcitation current; what is more, the high channel density in AAO can magnify the ion current signal response effectively by aggrandizing the flux of electroactive species. By using AAO photoresponsive nanochannels with an average diameter of 150 nm as PEC biosensor, an ultrasensitive detection record ranging from 0.01 fM to 0.01 nM with a detection limit of 3 aM can be achieved. This work not only proposes a simple method for manufacturing semiconductor photoresponsive nanochannels, but also exhibits great potential in the ultrasensitive detection of biomolecules.
Semiconductor molybdenum disulfide (MoS2)/porous anodic aluminum oxide (AAO) photoresponsive nanochannels are control fabricated using atomic layer deposition. A detection device is designed based on an ordinary photoelectrochemical (PEC) biosensor and photoresponsive nanochannel, which can not only produce photogenerated current but also be used as an ion channel. The MoS2/AAO‐based PEC biosensor has high sensitivity, selectivity, and practicability for the detection of miRNA‐155.
Aiming at the problems of low efficiency and poor accuracy in the product surface defect detection. In this paper, an online surface defects detection method based on YOLOV3 is proposed. Firstly, ...using lightweight network MobileNetV2 to replace the original backbone as the feature extractor to improve network speed. Then, we propose an extended feature pyramid network (EFPN) to extend the detection layer for multi-size object detection and design a novel feature fusing module (FFM) embedded in the extend layer to super-resolve features and capture more regional details. In addition, we add an IoU loss function to solve the mismatch between classification and bounding box regression. The proposed method is used to train and test on the hot rolled steel open dataset NEU-DET, which contains six typical defects of a steel surface, namely rolled-in scale, patches, crazing, pitted surface, inclusion and scratches. The experimental results show that our method achieves a satisfactory balance between performance and consumption and reaches 86.96% mAP with a speed of 80.96 FPS, which is more accurate and faster than many other algorithms and can realize real-time and high-precision inspection of product surface defects.
Adenosine triphosphate (ATP) is the most direct source of energy in organisms. This study is the first to demonstrate that ATP-aptamer complexes provide greater protection for unmodified gold ...nanoparticles (AuNPs) against salt-induced aggregation than either aptamer or ATP alone. This protective effect was confirmed using transmission electron microscopy, dynamic light scattering, Zeta potential measurement, and fluorescence polarization techniques. Utilizing controlled particle aggregation/dispersion as a gauge, a sensitive and selective aptasensor for colorimetric detection of ATP was developed using ATP-binding aptamers as the identification element and unmodified AuNPs as the probe. This aptasensor exhibited a good linear relationship between the absorbance and the logarithm concentration of ATP within a 50–1000nM range. ATP analogs such as guanosine triphosphate, uridine triphosphate and cytidine triphosphate resulted in little or no interference in the determination of ATP.
•The ATP-aptamer folding on the surface of unmodified AuNPs was first studied.•ATP-aptamer complexes could more effectively stabilize AuNPs than ATP or aptamer.•An ATP aptasensor was developed using label-free aptamers and unmodified AuNPs.•This aptasensor is highly sensitive and selective for ATP colorimetric detection.
•H2O2 alone has an effective action on TC degradation in faintly alkalinity medium.•TC degradation by H2O2 occurs via direct molecular reaction instead of radicals.•Nine products were identified, but ...only three ones were the final products.•The products were from hydroxylation, loss of group and cleavage of benzene ring.
The objective of this study was to investigate the degradation removal and pathway of tetracycline (TC) antibiotic from aqueous solution using H2O2 alone. Meanwhile, the effects of some operational parameters including initial concentration of H2O2 (29–580mM), pH (3.3–10), and contact time (10–180min) on the removal efficiency of TC were measured. The results showed that the removal of TC increased with increasing initial H2O2 dosage, pH and treatment time, and about 97% of TC was removed by H2O2 with the concentration of 174mM in alkaline aqueous solution. Experiments with different scavengers indicated that TC degradation occurred via a direct molecular reaction instead of active radicals. Nine transformation products were identified, but only three ones were the final products. These products resulted from hydroxylation, loss of some functional groups and cleavage of benzene rings of TC. These results demonstrated a new oxidative transformation pathway of TC induced by H2O2 without combination, further supporting the important role of oxidant species in the environmental fate of TCs.
This paper presents the results of an experimental program on the behavior of fiber-reinforced polymer (FRP)-concrete-high strength steel solid columns (FCSSCs), with an outer polyethylene ...terephthalate (PET) FRP tube and an inner circular high-strength steel (HSS) tube, under cyclic axial compression. A PET FRP tube has a much larger rupture strain and a larger FRP hoop strain efficiency, leading to an excellent ductility of PET FRP-confined concrete. The HSS tube, which has a good deformation compatibility with the PET FRP-confined concrete in FCSSCs, provides a much larger longitudinal load carrying capacity and a larger confinement to the core concrete compared with a normal strength steel tube. The experimental results demonstrated that the axial load carrying capacity of an FCSSC is much larger than the summation of the axial load resistance of the hollow steel tube and that of the concrete-filled FRP tube; the buckling of the HSS tube is also prevented so that its post-yield material strength is effectively utilized. It is found that cyclic load-strain envelope curves lie closely to the corresponding monotonic load-strain curves, and repeated loading cycles increase the plastic strain while decrease the reloading new stress. The existing stress-strain model fails to provide an accurate prediction on the cyclic axial behavior of concrete under combined PET FRP-steel confinement.
Hydrogen and other renewable resources derived by sunlight have attracted great attention to sustainable development. But the photochemical performance of diverse systems is restricted because of the ...poor efficiency of photon absorption, easy recombination of photogenerated electron–hole pairs, and slow transfer of charge carriers. Single-atom catalysts (SACs), in which isolated atoms are supported on the supports without forming nanoparticles, have received increasing interests in photocatalysis due to the high catalytic activity, selectivity, stability, and 100% atom utilization. In this review, we highlight and introduce recent advances in the preparation method of SACs and concrete examples of single-atom photocatalysts used for the hydrogen evolution from water, overall water splitting, CO2 and N2 reduction reaction. At last, we discuss the underlying mechanisms for photocatalytic performance of single-atom catalysts and the prospects for the development of SACs.
Fast magnetic resonance imaging (MRI) is crucial for clinical applications that can alleviate motion artefacts and increase patient throughput.
-space undersampling is an obvious approach to ...accelerate MR acquisition. However, undersampling of
-space data can result in blurring and aliasing artefacts for the reconstructed images. Recently, several studies have been proposed to use deep learning-based data-driven models for MRI reconstruction and have obtained promising results. However, the comparison of these methods remains limited because the models have not been trained on the same datasets and the validation strategies may be different. The purpose of this work is to conduct a comparative study to investigate the generative adversarial network (GAN)-based models for MRI reconstruction. We reimplemented and benchmarked four widely used GAN-based architectures including DAGAN, ReconGAN, RefineGAN and KIGAN. These four frameworks were trained and tested on brain, knee and liver MRI images using twofold, fourfold and sixfold accelerations, respectively, with a random undersampling mask. Both quantitative evaluations and qualitative visualization have shown that the RefineGAN method has achieved superior performance in reconstruction with better accuracy and perceptual quality compared to other GAN-based methods. This article is part of the theme issue 'Synergistic tomographic image reconstruction: part 1'.
Aim
To explore the relationship between job burnout and quality of working life, and identify influencing factors of nurses' quality of working life.
Background
Understanding the influencing factors ...of quality of working life is important to improve nursing retention strategies. Job burnout can negatively influence work efficiency and quality of work. However, studies examining the association between the two remain limited.
Methods
The cross‐sectional survey of 2,504 nurses was performed in Eastern China. Nurses were invited to complete self‐report questionnaires online. The collected data were analysed using Pearson's correlation and multiple regression.
Results
About 64.0% of nurses experienced job burnout, and their quality of working life was at a moderate level. Job burnout, hospital level, age, income, night shift and patient‐to‐nurse ratio were significant factors of quality of working life.
Conclusion
Job burnout has a negative effect on nurses' quality of working life. Some demographic and work‐related factors should be considered when developing interventions to improve nurses' quality of working life.
Implications for Nursing Management
Hospital and nurses managers should develop strategies to reduce nurses' job burnout and enhance their quality of working life, such as optimum nurse staffing, offer reasonable pecuniary compensation and establish an appropriate shift work schedule.
A mathematical model is proposed to analyze the spreading dynamics of COVID-19. By using the parameters of the model, namely the basic reproduction number (R0) and the attenuation constant (k), the ...daily number of infections (DNI) and the cumulative number of infections (CNI) over time (m) are deduced and shown to be in good agreement with experimental data. This model effectively addresses three key issues: (1) inferring the conditions under which virus infections die out for a specific strain given R0; (2) explaining the occurrence of second waves of infection and developing preventive measures; and (3) understanding the competitive spread of two viruses within a region and devising control strategies. The findings highlight the potential of this simple mathematical framework in comprehensively addressing these challenges. The theoretical insights derived from this model can guide the evaluation of infection wave severity and the formulation of effective strategies for controlling and mitigating epidemic outbreaks.
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