In this paper, the acceleration process of BaTiO3 ceramic particles under different vacuum cold spraying parameters was simulated, and the effect of process parameters on particle velocity was ...discussed. The results were verified using particle image velocimeter. BaTiO3 ceramic coatings were prepared using vacuum cold spraying method and their properties were tested. The simulation results showed that the particle velocity increased with the increase of gas pressure and preheating temperature. It was observed that under the same gas pressure and preheating temperature, the smaller the diameter of the particle, the more it was affected by the bow shock wave. The acceleration pattern of multiple particles was found to be similar to that of a single particle. According to the results obtained from particle image velocimetry, under the condition of and 300 K and 373 K at 0.2 MPa, the velocity of BaTiO3 particles differed from the simulation results by about 10.2% and 8.1%, respectively. Under the process paramete
Novel generation of analytical technology based on nanopores has provided possibilities to fabricate nanofluidic devices for low-cost DNA sequencing or rapid biosensing. In this paper, a simplified ...model was suggested to describe DNA molecule's translocation through a nanopore, and the internal potential, ion concentration, ionic flowing speed and ionic current in nanopores with different sizes were theoretically calculated and discussed on the basis of Poisson–Boltzmann equation, Navier–Stokes equation and Nernst–Planck equation by considering several important parameters, such as the applied voltage, the thickness and the electric potential distributions in nanopores. In this way, the basic ionic currents, the modulated ionic currents and the current drops induced by translocation were obtained, and the size effects of the nanopores were carefully compared and discussed based on the calculated results and experimental data, which indicated that nanopores with a size of 10 nm or so are more advantageous to achieve high quality ionic current signals in DNA sensing.
Heterostructures from two-dimensional transition-metal dichalcogenides MX2 have emerged as a hot topic in recent years due to their various fascinating properties. Here, we investigated the ...temperature dependent Raman and photoluminescence（PL） spectra in vertical stacked WS2/MoS2 monolayer heterostructures. Our result shows that both E2g1 and A1g modes of WS2 and MoS2 vary linearly with temperature increasing from 300 to 642 K. The PL measurement also reveals strong temperature dependencies of the PL intensity and peak position. The activation energy of the thermal quenching of the PL emission has been found to be equal to 69.6 meV. The temperature dependence of the peak energy well follows the bandgap shrinkage of bulk semiconductor.
We investigate the process of an ultrarelativistic fluid accreted onto axisymmetric Kerr-Sen black holes in Einstein-Maxwell-dilaton-axion theory. We obtain the solution describing the velocity ...potential of a stationary irrotational fluid with a stiff equation of state and the solution for the streamlined diagram of the quadrupolar flow. We also investigate how the solution's coefficients and the stagnation points are affected by the parameters. The injection rate, the ejection rate, and the critical angle are discussed in detail. We find that with an increasing dilaton parameter the ratio of the ejection rate to the injection rate increases and that the radiative efficiency is larger, while the redshift is lower, compared to the Kerr black hole.
The heavy ion beam is considered to be the ideal source for radiotherapy. The p53 tumor suppressor gene senses DNA damage and transducts intracellular apoptosis signals. Previous reports showed that ...the heavy ion beam can trigger complex forms of damage to cellular DNA, leading to cell cycle arrest and apoptosis of HepG2 human liver cancer cells; however, the mechanisms remains unclear fully. In order to explore whether the intrinsic or extrinsic pathway participates this process, HepG2 cells were treated with 1206＋ HIB irradiation at doses of 0 （control）, 1, 2, 4, and 6Gy with various methods employed to understand relevant mechanisms, such as detection of apoptosis, cell cycle, and Fas expression by flow cytometry, analysis of apoptotic morphology by electron microscopy and laser scanning confocal microscopy, and screening differentially expressed genes relating to p53 signaling pathway by PCR-array assay following with any genes confirmed by western blot analysis. This study showed that 1206＋ heavy ion beam irradiation at a dose of 6 Gy leads to endogenous DNA double-strand damage, G2/M cell cycle arrest, and apop- tosis of human HepG2 cells via synergistic effect of the extrinsic and intrinsic pathways. Differentially expressed genes in the p53 signaling pathway related to DNA damage repair, apop- tosis, cycle regulation, metastasis, deterioration and radioresistance were also discovered. Consequently, the expressions of Fas, TP53BP2, TP53AIP1, and CASP9 were confirmed upregu- lated after 1206＋ HIB irradiation treatment. In conclusion, this study demonstrated the mechanisms of inhibition and apoptosis induced by 1206＋ heavy ion beam irradiation on HepG2 cancer cells is mediated by initiation of the biological function of p53 signaling pathway including extrinsic and intrinsic apoptosis pathway.
Heterostructures from two-dimensional transition-metal dichalcogenides MX2 have emerged as a hot topic in recent years due to their various fascinating properties. Here, we investigated the ...temperature dependent Raman and photoluminescence （PL） spectra in vertical stacked WS2/MoS2 monolayer heterostructures. Our result shows that both E~g and Alg modes of WS2 and MoS2 vary linearly with tem- perature increasing from 300 to 642 K. The PL measurement also reveals strong temperature dependencies of the PL intensity and peak position. The activation energy of the thermal quenching of the PL emission has been found to be equal to 69.6 meV. The temperature dependence of the peak energy well follows the band- gap shrinkage of bulk semiconductor.
Summary Background Hand, foot, and mouth disease is a common childhood illness caused by enteroviruses. Increasingly, the disease has a substantial burden throughout east and southeast Asia. To ...better inform vaccine and other interventions, we characterised the epidemiology of hand, foot, and mouth disease in China on the basis of enhanced surveillance. Methods We extracted epidemiological, clinical, and laboratory data from cases of hand, foot, and mouth disease reported to the Chinese Center for Disease Control and Prevention between Jan 1, 2008, and Dec 31, 2012. We then compiled climatic, geographical, and demographic information. All analyses were stratified by age, disease severity, laboratory confirmation status, and enterovirus serotype. Findings The surveillance registry included 7 200 092 probable cases of hand, foot, and mouth disease (annual incidence, 1·2 per 1000 person-years from 2010–12), of which 267 942 (3·7%) were laboratory confirmed and 2457 (0·03%) were fatal. Incidence and mortality were highest in children aged 12–23 months (38·2 cases per 1000 person-years and 1·5 deaths per 100 000 person-years in 2012). Median duration from onset to diagnosis was 1·5 days (IQR 0·5–2·5) and median duration from onset to death was 3·5 days (2·5–4·5). The absolute number of patients with cardiopulmonary or neurological complications was 82 486 (case-severity rate 1·1%), and 2457 of 82486 patients with severe disease died (fatality rate 3·0%); 1617 of 1737 laboratory confirmed deaths (93%) were associated with enterovirus 71. Every year in June, hand, foot, and mouth disease peaked in north China, whereas southern China had semiannual outbreaks in May and September–October. Geographical differences in seasonal patterns were weakly associated with climate and demographic factors (variance explained 8–23% and 3–19%, respectively). Interpretation This is the largest population-based study up to now of the epidemiology of hand, foot, and mouth disease. Future mitigation policies should take into account the heterogeneities of disease burden identified. Additional epidemiological and serological studies are warranted to elucidate the dynamics and immunity patterns of local hand, foot, and mouth disease and to optimise interventions. Funding China–US Collaborative Program on Emerging and Re-emerging Infectious Diseases, WHO, The Li Ka Shing Oxford Global Health Programme and Wellcome Trust, Harvard Center for Communicable Disease Dynamics, and Health and Medical Research Fund, Government of Hong Kong Special Administrative Region.
The stabilization of black-phase formamidinium lead iodide (α-FAPbI
) perovskite under various environmental conditions is considered necessary for solar cells. However, challenges remain regarding ...the temperature sensitivity of α-FAPbI
and the requirements for strict humidity control in its processing. Here we report the synthesis of stable α-FAPbI
, regardless of humidity and temperature, based on a vertically aligned lead iodide thin film grown from an ionic liquid, methylamine formate. The vertically grown structure has numerous nanometer-scale ion channels that facilitate the permeation of formamidinium iodide into the lead iodide thin films for fast and robust transformation to α-FAPbI
A solar cell with a power-conversion efficiency of 24.1% was achieved. The unencapsulated cells retain 80 and 90% of their initial efficiencies for 500 hours at 85°C and continuous light stress, respectively.
Air quality is tightly correlated with human health, and long-term exposure to air pollution can pose a serious health risk to humans. In recent years, image-based air quality detection methods have ...been proposed and have achieved good accuracy in specific scenarios. However, most of the methods are still based on pure CNNs with fast inference speed but limited accuracy. Some also invoke a single channel or spatial attention mechanism, with improved accuracy but much slower inference speed. To have both advantages we propose the Spatial and Channel Calibration Network (SCCNet). The network combines spatial and channel attention to improve the detection efficiency and accuracy of the model by better extracting global information to focus computational resources on regions that are more important to the task. Our proposed channel averaging pooling (CAP) module significantly reduces the number of parameters in the model while extracting global information, improving the detection speed of the model. We also introduce a discrete cosine transform (DCT) method to transform images from the spatial domain to the frequency domain, which enhances the extraction of fine-grained features and improves the model’s classification ability for air quality detection tasks. Our experimental results show that SCCNet achieves an accuracy of 92.17% with about 30 million parameters in an air quality detection task, which is 1.65% and 1.71% more accurate than Swin Transformer (based on spatial attention) and SENet (based on channel attention) for a similar number of parameters. Our code and models will are publicly available at https://github.com/Fucheng-Wu/SCCNet.
•A refined design can significantly reduce the number of parameters in the network model.•The convergence of spatial and channel attention can substantially improve network performance.•Discrete cosine transform can enhance the ability of the network in extracting information.•Large-scale, high-quality data sets can provide more accurate results from experiments.
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