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Dear Editor, In December 2019, transmission of the novel coronavirus (SARS‐CoV‐2) that causes coronavirus disease 2019 (COVID‐19) occurred in Wuhan, China. 1 And later, the virus began to be transmitted from person to person. 2 Face masks are a type of personal protective equipment used to prevent the spread of respiratory infections, and it may be effective at helping prevent transmission of respiratory viruses and bacteria. 3 Here, we share a case of face masks are being used to prevent the transmission of COVID‐19 infection. According to epidemiological survey, 5 other passengers on the same coach bus were infected. Face masks are recommended for diseases transmitted through droplets and respirators for respiratory aerosols and may prevent infection in public settings. 6 The potential of face masks to reduce the spread of respiratory infections and could be useful. 7 In the study 8 of attitudes of influenza‐vaccinated healthcare workers toward masks, 65.7% of the participants agreed with infection control recommendation “wearing a mask” to prevent influenza transmission.

Cu2O-reduced graphene oxide nanocomposite (Cu2O-RGO) was used to modify glassy carbon electrodes (GCE), and applied for the determination of dopamine (DA). The microstructure of Cu2O-RGO nanocomposite material was characterized by scanning electron microscope. Then the electrochemical reduction condition for preparing Cu2O-RGO/GCE and experimental conditions for determining DA were further optimized. The electrochemical behaviors of DA on the bare electrode, RGO- and Cu2O-RGO-modified electrodes were also investigated using cyclic voltammetry in phosphate-buffered saline solution (PBS, pH 3.5). The results show that the oxidation peaks of ascorbic acid (AA), dopamine (DA), and uric acid (UA) could be well separated and the peak-to-peak separations are 204 mV (AA-DA) and 144 mV (DA-UA), respectively. Moreover, the linear response ranges for the determination of 1 × 10−8 mol/L~1 × 10−6 mol/L and 1 × 10−6 mol/L~8 × 10−5 mol/L with the detection limit 6.0 × 10−9 mol/L (S/N = 3). The proposed Cu2O-RGO/GCE was further applied to the determination of DA in dopamine hydrochloride injections with satisfactory results.

Accurate prediction of surface subsidence is of significance for analyzing the pattern of mining-induced surface subsidence, and for mining under buildings, railways, and water bodies. To address the problem that the existing prediction models ignore the correlation between subsidence points, resulting in large prediction errors, a Multi-point Relationship Fusion prediction model based on Graph Convolutional Networks (MRF-GCN) for mining-induced subsidence was proposed. Taking the surface subsidence in 82/83 mining area of Yuandian No. 2 Mine in Anhui Province in eastern China as an example, the surface deformation data obtained from 250 InSAR images captured by Sentinel-1A satellite from 2018 to 2022, combined with GNSS observation data, were used for modeling. The deformation pattern of each single observation point was obtained by feeding their deformation observation data into the LSTM encoder, after that, the relationship graph was created based on the correlation between points in the observation network and MRF-GCN was established. Then the prediction results came out through a nonlinear activation function of neural network. The research shows that the R 2 R2 value of MRF-GCN model was 0.865 0, much larger than that of Long-Short Term Memory (LSTM) and other conventional models, while mean square error (MSE) of MRF-GCN model was 1.59 899, much smaller than that of LSTM and other conventional models. Therefore, the MRF-GCN model has better prediction accuracy than other models and can be applied to predicting surface subsidence in large areas.

TiO2-reduced graphene oxide composite-modified glassy carbon electrodes (TiO2–ErGO–GCE) for the sensitive detection of tartrazine were prepared by drop casting followed by electrochemical reduction. The as-prepared material was characterized by transmission electron microscopy (TEM) and X-ray diffraction (XRD). Cyclic voltammetry and second-order derivative linear scan voltammetry were performed to analyze the electrochemical sensing of tartrazine on different electrodes. The determination conditions (including pH, accumulation potential, and accumulation time) were optimized systematically. The results showed that the TiO2–ErGO composites increased the electrochemical active area of the electrode and enhanced the electrochemical responses to tartrazine significantly. Under the optimum detection conditions, the peak current was found to be linear for tartrazine concentrations in the range of 2.0 × 10−8–2.0 × 10−5 mol/L, with a lower detection limit of 8.0 × 10−9 mol/L (S/N = 3). Finally, the proposed TiO2–ErGO–GCEs were successfully applied for the detection of trace tartrazine in carbonated beverage samples.

Objective Gut microbiota dysbiosis plays a vital role the pathogenesis of chronic obstructive pulmonary disease (COPD). This study aimed to: (1) examine the cross-sectional association between dietary index for gut microbiota (DI-GM), a novel biomarker reflecting gut microbiota composition and function, and COPD prevalence; and (2) assess the prognostic significance of DI-GM score for all-cause mortality in COPD patients. Methods We analyzed data from the 1999–2018 National Health and Nutrition Examination Survey. DI-GM score was calculated from 24-hour dietary recall. Primary outcomes were COPD prevalence and all-cause mortality risk in COPD patients. Multivariable logistic regression assessed the association between DI-GM and COPD prevalence, while Cox proportional hazards models evaluated all-cause mortality risk in COPD patients. Results The prevalence of COPD was 6.87% among the 22,859 participants included. Compared to participants with DI-GM score of 0–3, the odds ratio (95% confidence interval) for DI-GM score of 4, 5, and ≥ 6 were 0.88 (0.70–1.11), 0.78 (0.64–0.97), and 0.75 (0.62–0.90), respectively. During a median follow-up time of 84 months, a total of 570 (28.15%) participants died among the 1,580 COPD participants. Compared to DI-GM score of 0–3, the hazard ratios (95% confidence intervals) for DI-GM score of 4, 5, and ≥ 6 were 0.78 (0.60–1.01), 0.63 (0.47–0.83), and 0.69 (0.56–0.85), respectively. Conclusion Higher DI-GM scores are significantly associated with both reduced COPD prevalence and improved survival in COPD patients. Our results suggest dietary modifications targeting gut microbiota may represent a novel strategy for COPD prevention and management.

Amine-modified magnetite (NH2–Fe3O4)/reduced graphene oxide nanocomposite modified glassy carbon electrodes (NH2–Fe3O4/RGO/GCEs) were developed for the sensitive detection of dopamine (DA). The NH2-Fe3O4/RGO/GCEs were fabricated using a drop-casting method followed by an electrochemical reduction process. The surface morphologies, microstructure and chemical compositions of the NH2–Fe3O4 nanoparticles (NPs), reduced graphene oxide (RGO) sheets and NH2–Fe3O4/RGO nanocomposites were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-Ray diffraction (XRD) and Fourier-transform infrared (FTIR) spectroscopy. The electrochemical behaviors of DA on the bare and modified GCEs were investigated in phosphate buffer solution (PBS) by cyclic voltammetry (CV). Compared with bare electrode and RGO/GCE, the oxidation peak current (ipa) on the NH2–Fe3O4/RGO/GCE increase significantly, owing to the synergistic effect between NH2–Fe3O4 NPs and RGO sheets. The oxidation peak currents (ipa) increase linearly with the concentrations of DA in the range of 1 × 10−8 mol/L – 1 × 10−7 mol/L, 1 × 10−7 mol/L – 1 × 10−6 mol/L and 1 × 10−6 mol/L – 1 × 10−5 mol/L. The detection limit is (4.0 ± 0.36) ×10−9 mol/L (S/N = 3). Moreover, the response peak currents of DA were hardly interfered with the coexistence of ascorbic acid (AA) and uric acid (UA). The proposed NH2–Fe3O4/RGO/GCE is successfully applied to the detection of dopamine hydrochloride injections with satisfactory results. Together with low cost, facile operation, good selectivity and high sensitivity, the NH2–Fe3O4/RGO/GCEs have tremendous prospects for the detection of DA in various real samples.

CFRP composites have been widely used in many fields due to their excellent comprehensive performance. Precision machining of CFRP is the premise to ensure the efficient assembly of CFRP components. Therefore, it is important to clarify the material removal behavior for optimizing the process scheme and improving the machined surface quality. In this presented paper, the 3D finite element models including macro and micro models for CFRP cutting are found and verified by experiment. Based on four typical fiber orientation angles (FOAs), the micro-failure mechanism of CFRP and the formation mechanism of macro-chips under cutting load are studied. Finally, the machined surface quality of CFRP is studied using 3D nano system and scanning electron microscope (SEM). Results show that the damage of fiber and matrix on micro scale and the chip formation on macro scale are greatly affected by FOAs. Under different FOAs, the failure modes of fibers and matrix and the removal behavior of material are different, so that the machined surface quality is various. In this study, the relatively good surface quality is obtained when FOA is 45° or 90°, but a poor surface quality when FOA is 0°or 135°.

The synthetic jet piezoelectric air pump is a potential miniature device for electronic cooling. In order to improve the performance of the device, a small-sized synthetic jet piezoelectric air pump is proposed in this work, which is mainly characterized by petal-shaped inlet channels. First, the structure and working principle of the piezoelectric vibrator and the proposed pump are analyzed. Then, three synthetic jet piezoelectric air pumps with different inlet channels are compared. These inlets are the direct channels, the diffuser/nozzle channels, and the petal-shaped channels, respectively. Furthermore, the performance of the synthetic jet piezoelectric air pump with the petal-shaped inlet channels is optimized by orthogonal tests. Finally, the simulation was used to investigate the heat dissipation capability of the synthetic jet piezoelectric pump. The experimental results show that among the three inlet channels, the petal-shaped channel can greatly improve the performance of the pump. The unoptimized pump with petal-shaped channels has a maximum flow rate of 1.8929 L/min at 100 V, 3.9 kHz. Additionally, the optimized pump with petal-shaped channels reaches a maximum flow rate of 3.0088 L/min at 100 V, 3.7 kHz, which is 58.95% higher than the unoptimized one. The proposed synthetic jet piezoelectric air pump greatly improves the output performance and has the advantages of simple structure, low cost, and easy integration. The convective heat transfer coefficient of the synthetic jet piezoelectric pump is 28.8 W/(m2·°C), which can prove that the device has a better heat dissipation capability.

In this paper, the time-independent Klein-Gordon equation in R3 is treated with a decomposition of the operator Δ−γ2I by the Clifford algebra Cl(V3,3). Some properties of integral operators associated the kind of equations and some Riemann-Hilbert boundary value problems for perturbed Dirac operators are investigated.

The pressing crisis of clean water shortage requires membranes to possess effective ion sieving as well as fast water flux. However, effective ion sieving demands reduction of pore size, which inevitably hinders water flux in hydrophilic membranes, posing a major challenge for efficient water/ion separation. Herein, we introduce anomalous water molecular gating based on nanofiltration membranes full of graphene capillaries at 6 Å, which were fabricated from spontaneous π-π restacking of island-on-nanosheet graphitic microstructures. We found that the membrane can provide effective ion sieving by suppressing osmosis-driven ion diffusion to negligible levels (~10 –4 mol m –2 h –1 ); unexpectedly, ultrafast bulk flow of water (45.4 L m –2 h –1 ) was still functional with ease, as gated on/off by adjusting hydrostatic pressures within only 10 –2 bar. We attribute this seemingly incompatible observation to graphene nanoconfinement effect, where crystal-like water confined within the capillaries hinders diffusion under osmosis but facilitates high-speed, diffusion-free water transport in the way analogous to Newton’s cradle-like Grotthus conduction. This strategy establishes a type of liquid-solid-liquid, phase-changing molecular transport for precise and ultrafast molecular sieving. Here authors present water molecular gating in nanofiltration membranes featuring graphene capillaries, which exhibit hindered osmotic diffusion while enabling swift water transport similar to Newton’s cradle-like Grotthus conduction.