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学者姓名:张楠
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摘要 :
Debate and scientific inquiries regarding airborne transmission of respiratory infections such as COVID-19 and influenza continue. Health authorities including the WHO and the US CDC have recognized the airborne transmission of COVID-19 in specific settings, although the ventilation requirements remain to be determined. In this work we consider the long-range airborne transmission as an extended short-range airborne route, which reconciles the link between short- and long-range airborne routes. The effective short-range distance is defined as the distance in short range at which long-range route has the same volumetric exposure value as that due to short-range route. Our data show that a decrease in ventilation rate or room volume per person, or an increase in the ratio of the number of infected to susceptible people reduces the effective short-range distance. In a normal breathing scenario with one out of five people infected and a room volume of 12 m3 per person to ensure an effective short-range distance of 1.5 m, a ventilation rate of 10 L/s per person is needed for a duration of 2 h. Our results suggest that effective environmental prevention strategies for respiratory infections require appropriate increases in the ventilation rate while maintaining a sufficiently low occupancy. Practical implications: Demonstration of the long-range airborne route as an extended short-range airborne route suggests the significant role played by building ventilation in respiratory infection exposure. The reconciliation of short- and long-range airborne transmission suggests that the commonly observed dominance of close-contact transmission is a probable evidence of short-range airborne transmission, following a separate earlier study that revealed the relative insignificance of large droplet transmission in comparison with the short-range airborneroute. Existing ventilation standards do not account for respiratory infection control, and this study presents a possible approach to account for infection under new ventilation standards.
关键词 :
Airborne transmission Airborne transmission COVID-19 COVID-19 Crowding Crowding Indoor environment Indoor environment Ventilation rate Ventilation rate
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GB/T 7714 | Chen, Wenzhao , Qian, Hua , Zhang, Nan et al. Extended short-range airborne transmission of respiratory infections [J]. | JOURNAL OF HAZARDOUS MATERIALS , 2022 , 422 . |
MLA | Chen, Wenzhao et al. "Extended short-range airborne transmission of respiratory infections" . | JOURNAL OF HAZARDOUS MATERIALS 422 (2022) . |
APA | Chen, Wenzhao , Qian, Hua , Zhang, Nan , Liu, Fan , Liu, Li , Li, Yuguo . Extended short-range airborne transmission of respiratory infections . | JOURNAL OF HAZARDOUS MATERIALS , 2022 , 422 . |
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摘要 :
通过构建数学模型,定量研究了1个3人家庭环境中飞沫传播、接触传播和气溶胶传播在COVID-19传播中的作用。研究表明,飞沫传播和接触传播在COVID-19传播中起着最重要的作用。和患者交流时保持1.5~2 m的空间距离对控制飞沫传播至关重要,洗手和保护环境表面清洁是控制接触传播的最有效手段。虽然通过气溶胶途径传播风险相对较小,但当患者呼出飞沫中病原体浓度较高时(患者可能为超级感染者),在家庭环境中24 h暴露下,气溶胶传播风险依然可以高达26%。
关键词 :
接触传播 接触传播 数学模型 数学模型 新型冠状病毒 新型冠状病毒 气溶胶传播 气溶胶传播 相对重要性 相对重要性 飞沫传播 飞沫传播
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GB/T 7714 | 雷浩 , 肖胜蓝 , 张楠 et al. 新型冠状病毒在家庭环境中的主要传播途径 [J]. | 科技导报 , 2021 , 39 (09) : 78-86 . |
MLA | 雷浩 et al. "新型冠状病毒在家庭环境中的主要传播途径" . | 科技导报 39 . 09 (2021) : 78-86 . |
APA | 雷浩 , 肖胜蓝 , 张楠 , 魏健健 , 金滔 . 新型冠状病毒在家庭环境中的主要传播途径 . | 科技导报 , 2021 , 39 (09) , 78-86 . |
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摘要 :
Following advancement in urbanization, outdoor thermal comfort is receiving increasing attention, with radiation being an influencing factor. To determine the shading preference, instead of a subjective questionnaire survey, an objective foot vote approach was proposed using remote sensing images. Subsequently, the meteorological data of cities were obtained from the Bureau of Meteorology. From the results, the foot vote was approximately consistent with the PMV, and pedestrians tended to move to the shaded area if it was hot and to the non-shaded area if it was cold. However, people do not move if the foot vote value ranges from 1 to 2, and the thermal acceptance range of PET is 19.2–29 °C in Beijing when using the definitions of foot vote. The outdoor thermal acceptance differs significantly with the types of outdoor sites and climates, and pedestrians in Beijing are significantly more sensitive than those in Wuhan if the outdoor thermal environment changes. Compared to transportation hubs and shopping malls, pedestrians in public buildings are less sensitive, whereas those in scenic spots are more sensitive. Results from this study will be beneficial to policymakers in urban designing to renovate and improve thermally comfortable urban environments at the pedestrian level. © 2021 Elsevier Ltd
关键词 :
Meteorology Meteorology Remote sensing Remote sensing Surveys Surveys Thermal comfort Thermal comfort
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GB/T 7714 | Xue, Peng , Jia, Xiaoyu , Lai, Dayi et al. Investigation of outdoor pedestrian shading preference under several thermal environment using remote sensing images [J]. | Building and Environment , 2021 , 200 . |
MLA | Xue, Peng et al. "Investigation of outdoor pedestrian shading preference under several thermal environment using remote sensing images" . | Building and Environment 200 (2021) . |
APA | Xue, Peng , Jia, Xiaoyu , Lai, Dayi , Zhang, Xiaojing , Fan, Cheng , Zhang, Weirong et al. Investigation of outdoor pedestrian shading preference under several thermal environment using remote sensing images . | Building and Environment , 2021 , 200 . |
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摘要 :
The effect of hydrodynamic force on the seismic response of structure in water cannot be ignored. Various methods have been developed to describe the effect of incompressible water, but the relative performance of some practical simplified methods is largely unknown. In this paper a comprehensive comparison of three representative simplified methods for assessing cylindrical hydrodynamic force is presented. Relative errors of structural elastic peak responses are constructed to measure the accuracy of the simplified method. The errors are tested on 154 circular cylinders subjected to 100 ground motions. The errors were first obtained by averaging the results of ground motions. Then the comparison between methods and the influence of parameters were studied based on the mean errors. Furthermore, by analyzing the statistical characteristic values of the errors, the kernel density estimation method was adopted to obtain the probability density of the errors. Finally, the probabilities of cylindrical cases and methods were investigated. The results show that if the added mass of hydrodynamic force depends on more structural parameters, the accuracy of the method may higher. The rigid-structure method has the highest accuracy and the most complicated expression. The accuracy and complexity of the method based on approximation of fundamental frequency are moderate. The Morison method has the simplest form and the maximum error. The results indicate that the added mass should relate to several structural parameters, ignoring the change of the added mass along the height will bring error to method and assuming the structure to be rigid is an effective way to simplify the analytical hydrodynamics.
关键词 :
Probability density Probability density Seismic response Seismic response Simplified method Simplified method Water-cylinder interaction Water-cylinder interaction
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GB/T 7714 | Guo, Jie , Zhao, Mi , Wang, Piguang et al. Comparative assessment of simplified methods for hydrodynamic force on cylinder under earthquakes [J]. | OCEAN ENGINEERING , 2021 , 234 . |
MLA | Guo, Jie et al. "Comparative assessment of simplified methods for hydrodynamic force on cylinder under earthquakes" . | OCEAN ENGINEERING 234 (2021) . |
APA | Guo, Jie , Zhao, Mi , Wang, Piguang , Zhang, Nan . Comparative assessment of simplified methods for hydrodynamic force on cylinder under earthquakes . | OCEAN ENGINEERING , 2021 , 234 . |
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摘要 :
The association between the footwear microclimate and microbial community on the foot plantar skin was investigated by experiments with three participants. Novel methods were developed for measuring in-shoe temperature and humidity at five footwear regions, as well as the overall ventilation rate inside the footwear. Three types of footwear were tested including casual shoes, running shoes, and perforated shoes for pairwise comparison of footwear microclimate and corresponding microbial community on the skin. The major findings are as follows: (1) footwear types make a significant difference to in-shoe temperature at the instep region with the casual shoes sustaining the warmest of all types; (2) significant differences were observed in local internal absolute humidity between footwear types, with the casual shoes sustaining the highest level of humidity at most regions; (3) the perforated shoes provided the highest ventilation rate, followed by running and casual shoes, and the faster the gait, the larger the discrepancy in ventilation rate between footwear types; (4) the casual shoes seemed to provide the most favorable internal environment for bacterial growth at the distal plantar skin; and (5) the bacterial growth at the distal plantar skin showed a positive linear correlation with the in-shoe temperature and absolute humidity, and a negative linear correlation with the ventilation rate. The ventilation rate seemed to be a more reliable indicator of the bacterial growth. Above all, we can conclude that footwear microclimate varies in footwear types, which makes contributions to the bacterial growth on the foot plantar skin.
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GB/T 7714 | Miao, Te , Wang, Peihua , Zhang, Nan et al. Footwear microclimate and its effects on the microbial community of the plantar skin [J]. | SCIENTIFIC REPORTS , 2021 , 11 (1) . |
MLA | Miao, Te et al. "Footwear microclimate and its effects on the microbial community of the plantar skin" . | SCIENTIFIC REPORTS 11 . 1 (2021) . |
APA | Miao, Te , Wang, Peihua , Zhang, Nan , Li, Yuguo . Footwear microclimate and its effects on the microbial community of the plantar skin . | SCIENTIFIC REPORTS , 2021 , 11 (1) . |
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摘要 :
Personal protective behaviors and their dynamic change are known to play a major role in the community spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causal pathogen of the coronavirus disease 2019 (COVID-19) pandemic. In this study, a total of 3229 students in Chinese universities completed an online survey about their knowledge on transmission and personal protective behavior before and after COVID19 vaccination. Of the respondents, 87.6% had been vaccinated. Most students believed that the large droplet (97.0%) and short-range airborne (89.3%) routes were the two most likely SARS-CoV-2 transmission routes, whereas only 24.1% considered long-range airborne transmission to be possible. Students who would be expected to possess better knowledge about virus transmission (e.g., students of medicine) reported better personal protective behaviors. Female students reported relatively better personal hygiene practices than male students, so did the confident students than their diffident peers. Students washed their hands on average of 5.76 times per day during the pandemic. Students at universities in southern regions washed their hands more frequently but paid less attention to indoor ventilation than did their northern counterparts. Interestingly, students who are fear of being infected had the bad personal hygiene. University students wore 22% less masks in public indoor environments after vaccination. Chinese university students weakened their personal protective behavior after vaccination and it may increase the potential risk of infection in the new waves of variant virus (e.g. delta).
关键词 :
COVID-19 COVID-19 Mask Mask Personal hygiene Personal hygiene Personal protective behavior Personal protective behavior University student University student Vaccination Vaccination
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GB/T 7714 | Zhang, Nan , Liu, Xiyue , Jin, Tianyi et al. Weakening personal protective behavior by Chinese university students after COVID-19 vaccination [J]. | BUILDING AND ENVIRONMENT , 2021 , 206 . |
MLA | Zhang, Nan et al. "Weakening personal protective behavior by Chinese university students after COVID-19 vaccination" . | BUILDING AND ENVIRONMENT 206 (2021) . |
APA | Zhang, Nan , Liu, Xiyue , Jin, Tianyi , Zhao, Pengcheng , Miao, Doudou , Lei, Hao et al. Weakening personal protective behavior by Chinese university students after COVID-19 vaccination . | BUILDING AND ENVIRONMENT , 2021 , 206 . |
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摘要 :
The photocatalytic activity of polymeric carbon nitride (g-C3N4) strongly depends on its electronic structure which is highly sensitive to the preparation methods. To design the photocatalysts with efficient charge separation and transfer property, here we report a new ethylenediamine (EDA) induced gas-solid grafting method which enables the asymmetric modification of g-C3N4 featuring the aromatization at the terminal of melon motifs. The obtained terminal-aromatized g-C3N4 (Ar-C3N4) exhibits an improved visible-light-driven photocatalytic activity in versatile two-electron reduction reactions, outperforming the pristine g-C3N4 by 15.4 and 6.6 folds respectively in hydrogen evolution and hydrogen peroxide production. Theoretical and experimental results demonstrate the intensified asymmetry of p-electron distribution in the resulting material, which provides significantly improved driving force to guide the efficient separation of photogenerated e-h pairs and enhance the charge carrier mobility compared to its symmetric counterpart.
关键词 :
Aromatization Aromatization Asymmetric structure Asymmetric structure Gas-solid grafting reaction Gas-solid grafting reaction Photocatalytic reductions Photocatalytic reductions Terminal blocking Terminal blocking
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GB/T 7714 | Luo, Wei , Li, Yongli , Wang, Jinshu et al. Asymmetric structure engineering of polymeric carbon nitride for visible-light-driven reduction reactions [J]. | NANO ENERGY , 2021 , 87 . |
MLA | Luo, Wei et al. "Asymmetric structure engineering of polymeric carbon nitride for visible-light-driven reduction reactions" . | NANO ENERGY 87 (2021) . |
APA | Luo, Wei , Li, Yongli , Wang, Jinshu , Liu, Jingchao , Zhang, Nan , Zhao, Mengdi et al. Asymmetric structure engineering of polymeric carbon nitride for visible-light-driven reduction reactions . | NANO ENERGY , 2021 , 87 . |
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摘要 :
Background: School closure is a common mitigation strategy during severe influenza epidemics and pandemics. However, the effectiveness of this strategy remains controversial. In this study, we aimed to explore the effectiveness of school closure on seasonal influenza epidemics in provincial-level administrative divisions (PLADs) with varying urbanization rates in China. Methods: This study analyzed influenza surveillance data between 2010 and 2019 provided by the Chinese National Influenza Center. Taking into consideration the climate, this study included a region with 3 adjacent PLADs in Northern China and another region with 4 adjacent PLADs in Southern China. The effect of school closure on influenza transmission was evaluated by the reduction of the effective reproductive number of seasonal influenza during school winter breaks compared with that before school winter breaks. An age-structured Susceptible-Infected-Recovered-Susceptible (SIRS) model was built to model influenza transmission in different levels of urbanization. Parameters were determined using the surveillance data via robust Bayesian method. Results: Between 2010 and 2019, in the less urbanized provinces: Hebei, Zhejiang, Jiangsu and Anhui, during school winter breaks, the effective reproductive number of seasonal influenza epidemics reduced 14.6% [95% confidential interval (CI): 6.2-22.9%], 9.6% (95% CI: 2.5-16.6%), 7.3% (95% CI: 0.1-14.4%) and 8.2% (95% CI: 1.1-15.3%) respectively. However, in the highly urbanized cities: Beijing, Tianjin and Shanghai, it reduced only 5.2% (95% CI: -0.7-11.2%), 4.1% (95% CI: -0.9-9.1%) and 3.9% (95% CI: -1.6-9.4%) respectively. In China, urbanization is associated with decreased proportion of children and increased social contact. According to the SIRS model, both factors could reduce the impact of school closure on seasonal influenza epidemics, and the proportion of children in the population is thought to be the dominant influencing factor. Conclusions: Effectiveness of school closure on the epidemics varies with the age structure in the population and social contact patterns. School closure should be recommended in the low urbanized regions in China in the influenza seasons.
关键词 :
China China Contact Contact Influenza epidemics Influenza epidemics School closure School closure Urbanization Urbanization
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GB/T 7714 | Lei, Hao , Jiang, Hangjin , Zhang, Nan et al. Increased urbanization reduced the effectiveness of school closures on seasonal influenza epidemics in China [J]. | INFECTIOUS DISEASES OF POVERTY , 2021 , 10 (1) . |
MLA | Lei, Hao et al. "Increased urbanization reduced the effectiveness of school closures on seasonal influenza epidemics in China" . | INFECTIOUS DISEASES OF POVERTY 10 . 1 (2021) . |
APA | Lei, Hao , Jiang, Hangjin , Zhang, Nan , Duan, Xiaoli , Chen, Tao , Yang, Lei et al. Increased urbanization reduced the effectiveness of school closures on seasonal influenza epidemics in China . | INFECTIOUS DISEASES OF POVERTY , 2021 , 10 (1) . |
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摘要 :
By the end of February 2021, COVID-19 had spread to over 230 countries, with more than 100 million confirmed cases and 2.5 million deaths. To control infection spread with the least disruption to economic and societal activities, it is crucial to implement the various interventions effectively. In this study, we developed an agentbased SEIR model, using real demographic and geographic data from Hong Kong, to analyse the efficiency of various intervention strategies in preventing infection by the SARS-CoV-2 virus. Close contact route including short-range airborne is considered as the main transmission routes for COVID-19 spread. Contact tracing is not that useful if all other interventions have been fully deployed. The number of infected individuals could be halved if people reduced their close contact rate by 25%. For reducing transmission, students should be prioritized for vaccination rather than retired older people and preschool aged children. Home isolation, and taking the nucleic acid test (NAT) as soon as possible after symptom onset, are much more effective interventions than wearing masks in public places. Temperature screening in public places only disrupted the infection spread by a small amount when other interventions have been fully implemented. Our results may be useful for other highly populated cities, when choosing their intervention strategies to prevent outbreaks of COVID-19 and similar diseases.
关键词 :
Close contact Close contact COVID-19 COVID-19 Mask Mask SEIR model SEIR model Temperature screening Temperature screening Vaccine Vaccine
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GB/T 7714 | Zhang, Nan , Chan, Pak-To Jack , Jia, Wei et al. Analysis of efficacy of intervention strategies for COVID-19 transmission: A case study of Hong Kong [J]. | ENVIRONMENT INTERNATIONAL , 2021 , 156 . |
MLA | Zhang, Nan et al. "Analysis of efficacy of intervention strategies for COVID-19 transmission: A case study of Hong Kong" . | ENVIRONMENT INTERNATIONAL 156 (2021) . |
APA | Zhang, Nan , Chan, Pak-To Jack , Jia, Wei , Dung, Chung-Hin , Zhao, Pengcheng , Lei, Hao et al. Analysis of efficacy of intervention strategies for COVID-19 transmission: A case study of Hong Kong . | ENVIRONMENT INTERNATIONAL , 2021 , 156 . |
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摘要 :
Fomites are known to spread infectious diseases, but their role in determining transmission risk remains unclear. The association of surface touch networks (STNs), proposed to explain this risk, with real-life surface contamination has not yet been demonstrated. To construct STNs, we collected surface touch data from 23 to 26 scholars through 2 independent experiments conducted in office spaces for 13 h each. In parallel, a tracer bacterium (Lactobacillus bulgaricus) was spread by a designated carrier in each experiment during normal activities; the subsequent extent of surface contamination was assessed using qPCR. The touch data were also analyzed using an agent-based model that predicted the observed contamination. Touching public (door handles) and hidden public (desks, chair seatbacks) surfaces that connected occupants, sparse hand-to-hand contact, and active carriers contributed significantly to contamination spread, which was also correlated with the size of the social group containing carriers. The natural and unsupervised experiments reflected realistic exposure levels of mouths (1-10 ppm of total contamination spread by one root carrier), nostrils (-1 ppm), and eyes (-0.1 ppm). We conclude that the contamination degree of known and hidden public surfaces can indicate fomite exposure risk. The social group effect could trigger superspreading events through fomite transmission.
关键词 :
Fomite exposure Fomite exposure Infection control Infection control Surface hygiene Surface hygiene Surface touch network Surface touch network Surrogate tracer Surrogate tracer
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GB/T 7714 | Wang, Peihua , Zhang, Nan , Miao, Te et al. Surface touch network structure determines bacterial contamination spread on surfaces and occupant exposure [J]. | JOURNAL OF HAZARDOUS MATERIALS , 2021 , 416 . |
MLA | Wang, Peihua et al. "Surface touch network structure determines bacterial contamination spread on surfaces and occupant exposure" . | JOURNAL OF HAZARDOUS MATERIALS 416 (2021) . |
APA | Wang, Peihua , Zhang, Nan , Miao, Te , Chan, Jack P. T. , Huang, Hong , Lee, Patrick K. H. et al. Surface touch network structure determines bacterial contamination spread on surfaces and occupant exposure . | JOURNAL OF HAZARDOUS MATERIALS , 2021 , 416 . |
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