Search

Solid waste generation has been significantly accelerated by the rapid growth of economy and population worldwide. The traditional waste management focusing on waste utilization and disposal is unable to unravel the continuous depletion of finite natural resources. "Zero waste" as an integrated waste management method to promote waste reduction through a pack of strategies such as cleaner production and green consumption has emerged. Here, we systematically reviewed the researches on zero waste from a scientometric perspective, and visually unveiled the most productive countries, evolution process, main authors, major research areas, and documents of zero waste research domain. The results show that with increased publications, zero waste has become a multidisciplinary study area and food waste reduction is the biggest sub-network in zero waste research. The current research frontiers are mainly regarding "lean production," "consumer behavior," "productivity." Accordingly, this study proposed a pathway for realizing zero waste cities with three lanes: (1) research and development, (2) management method, and (3) policy and implementation. The findings are also expected to be beneficial to latecomer researches in the waste management field., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

As important pollution gases and represented precursors of both ozone and second organic aerosol (SOA), the component characteristics, source origins, environmental health and emission control of volatile organic compounds (VOCs), are gaining more and more attention in Chinese megacities. In order to understand the concentration, composition and temporal and spatial distribution characteristics of VOCs in the atmosphere of Chengdu, a megacity located in Sichuan basin in southwest China, the offline sampling measurements of VOCs were carried out at 28 different field sites covering all the districts and counties of Chengdu during special periods from May 2016 to January 2017. Speciated VOCs measurement was performed by the GC-FID/MS, and 99 species were identified. The averaged total VOC mixing ratios of each sampling site were in the range from 35.03 to 180.57 ppbv. Based on these observational data, the distribution characteristics of VOCs in different months and different regions of Chengdu were clarified. The VOCs data were used to estimate the potential amount of ozone, secondary aerosol formation and health risk assessment in Chengdu. Furthermore, the positive matrix factorization (PMF) model was used to identify the dominant emission sources and evaluate their contribution to VOCs in the city. The two main sources of VOCs in Chengdu were motor vehicle exhaust and solvent utilization. These accounted for 43% of all emission sources. In the summertime, due to higher temperatures and stronger sunlight, the contribution of natural sources and secondary emissions were also relatively high, which were supported by the regional emission inventories. Finally, the controlling direction of VOCs and O 3 pollution in Chengdu was discussed, and the VOCs pollution control strategy was proposed for the near future., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Importance: Sustained spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has happened in major US cities. Capacity needs in cities in China could inform the planning of local health care resources., Objectives: To describe and compare the intensive care unit (ICU) and inpatient bed needs for patients with coronavirus disease 2019 (COVID-19) in 2 cities in China to estimate the peak ICU bed needs in US cities if an outbreak equivalent to that in Wuhan occurs., Design, Setting, and Participants: This comparative effectiveness study analyzed the confirmed cases of COVID-19 in Wuhan and Guangzhou, China, from January 10 to February 29, 2020., Exposures: Timing of disease control measures relative to timing of SARS-CoV-2 community spread., Main Outcomes and Measures: Number of critical and severe patient-days and peak number of patients with critical and severe illness during the study period., Results: In Wuhan, strict disease control measures were implemented 6 weeks after sustained local transmission of SARS-CoV-2. Between January 10 and February 29, 2020, patients with COVID-19 accounted for a median (interquartile range) of 429 (25-1143) patients in the ICU and 1521 (111-7202) inpatients with serious illness each day. During the epidemic peak, 19 425 patients (24.5 per 10 000 adults) were hospitalized, 9689 (12.2 per 10 000 adults) were considered in serious condition, and 2087 (2.6 per 10 000 adults) needed critical care per day. In Guangzhou, strict disease control measures were implemented within 1 week of case importation. Between January 24 and February 29, COVID-19 accounted for a median (interquartile range) of 9 (7-12) patients in the ICU and 17 (15-26) inpatients with serious illness each day. During the epidemic peak, 15 patients were in critical condition and 38 were classified as having serious illness. The projected number of prevalent critically ill patients at the peak of a Wuhan-like outbreak in US cities was estimated to range from 2.2 to 4.4 per 10 000 adults, depending on differences in age distribution and comorbidity (ie, hypertension) prevalence., Conclusions and Relevance: Even after the lockdown of Wuhan on January 23, the number of patients with serious COVID-19 illness continued to rise, exceeding local hospitalization and ICU capacities for at least a month. Plans are urgently needed to mitigate the consequences of COVID-19 outbreaks on the local health care systems in US cities.

Dengue fever, a mosquito-borne viral disease in humans, has been endemic in many Southeast Asian countries. Since its first outbreak in 1978 in Foshan, Guangdong province, China, dengue has been continually epidemic in recent years in Guangdong, which raised the concern whether dengue infection is endemic in Guangdong. In this study, we performed phylogenetic, recombinant, and nucleotide variation analyses of 114 complete genome sequences of dengue virus serotypes 1-4 (DENV1-4) collected from 2013 to 2017 in 18 of 21 cities of Guangdong. Phylogenetic analyses revealed that DENV sequences did not form a single cluster, indicating that dengue fever was not endemic in Guangdong, although DENV1-4 co-circulated in Guangdong. Twenty intra-serotype recombinant isolates involving DENV1-4 were detected, but no inter-serotype recombinant events were identified in this study. Additionally, the most recombinant events were detected simultaneously in the gene NS3 of DENV1-4. Nucleotide variation analyses showed that no significant intra-serotype differences were observed, whereas more significant inter-subtype differences were discovered in non-structural genes than in structural genes. Our investigation will facilitate the understanding of the current prevalent status of dengue fever in Guangdong and contribute to designing more effective preventive and control strategies for dengue infection., Competing Interests: The authors have declared that no competing interests exist.

A severe haze episode occurred in winter in the North China Plain (NCP), and the phenomenon of an explosive growth and sharp decline in PM 2.5 (particulate matter with an aerodynamic diameter equal to or less than 2.5 μm) concentration was observed. To study the systematic causes for this phenomenon, comprehensive observations were conducted in Beijing from November 26 to December 2, 2015; during this period, meteorological parameters, LIDAR data, and the chemical compositions of aerosols were determined. The haze episode was characterized by rapidly varying PM 2.5 concentration, and the highest PM 2.5 concentration reached 667 μg/m 3 . During the haze episode, the NCP was dominated by a weak high-pressure system and continuously low PBL (planetary boundary layer) heights, which are unfavorable conditions for the diffusion of pollutants. The large increases in the concentrations of SNA (SO 4 2- , NO 3 - and NH 4 + ) during the haze implied that the formation of SNA was the largest contribution. Water vapor also played a vital role in the formation of haze by promoting the chemical transformation of secondary pollutants, which led to higher PM 2.5 concentrations. The spatial distributions of PM 2.5 in Beijing at different times and the backward trajectories of the air masses also indicated that pollutants from surrounding provinces in particular, contributed to the higher PM 2.5 concentration., (Copyright © 2019. Published by Elsevier B.V.)

A continuous online observation of ozone and its precursors (NOx, VOCs) was carried out in central urban Wuhan from September 2016 to August 2017. The concentration levels of ozone, NOx, VOCs and their variations in urban Wuhan were analyzed, as well as effects of VOCs on ozone photochemical generation and the main controlling factors for ozone production. During the observation period, the average concentrations of ozone and NOx in Wuhan was 22.63 and 30.14 ppbv, respectively, and the average concentration of VOCs was 32.61 ppbv (42.3% alkanes, 13.0% alkenes, 10.0% aromatics, 7.3% acetylene, 9.9% OVOCs, and 10.5% halohydrocarbons). Ozone concentration was higher in spring and summer as compared with autumn and winter, wheras VOCs and NOx concentratios were lower in spring and summer but higher in autumn and winter. Aromatics and alkenes, two of VOCs species, showed the highest contributions to ozone formation potential in Wuhan (35.7% alkenes, 35.4 aromatics, 17.5% alkanes, 8.6% OVOCs, 1.6% halogenated hydrocarbons, and 1.4% acetylene). Among all VOCs species, those with the highest contribution were ethylene, m-xylene, toluene, propylene and o-xylene. The contribution of these five compounds to the total ozone formation potential concentration was 43.90%. Ozone-controlling factors in Wuhan changed within one day; during the early morning hours (6:00-9:00), VOCs/NOx was low, and ozone generation followed a VOCs-limited regime. However, during the peak time of ozone concentration (12:00-16:00), the ratio of VOCs/NOx was relatively high, suggesting that ozone generation followed a NOx-limited regime., (Copyright © 2018. Published by Elsevier B.V.)

Objective: To understand the homosexual behavior and related factors among married MSM in Mianyang city. Methods: Between January and October in 2017, a snowball sampling method was adopted to carry out cross-sectional survey through questionnaires plus HIV testing among those MSM in Mianyang city. Logistic regression model was used to analyze homosexual behaviors and related factors among married MSM under study. Statistical analysis was used by EpiData 3.1 and SPSS 19.0 software. Results: A total of 234 MSM participated in this survey. The overall rate of homosexual behavior in these married MSM appeared as 94.9 % (222/234). Rate of having anal sex behavior was 94.4 % (221/234) in the past 6 months, with rate of condom use as 57.9 % (128/221). HIV positive rate was 8.1 % (18/222). As for the motives for homosexual behavior after marriage, 87.8 % (195/222) were driven by feelings of love, 12.2 % (27/222) due to 'releasing pressure'. Proportion of male sex partners would include occasional sex partners (62.2 % , 138/222), stable male sex partners (26.1 % , 58/222) and stable boyfriends (11.7 % , 26/222). Factors from logistic regression analysis showed that homosexual behaviors were related to the factors including education level of senior high school or above vs. education level of junior middle school or below ( OR =3.65, 95 %CI : 1.33-9.98); local residency over one year vs. the ones having local residency less than one year ( OR =23.28, 95 %CI :1.67-324.89); having 10 or more friends in the MSM community vs. having below 10 friends in MSM community ( OR =4.15, 95 %CI : 1.28-13.43); without sex pleasure with spouse vs. having sex pleasure with spouse ( OR =3.25, 95 %CI : 1.22-8.62); having 2 or more anal sex partners in the past 6 months vs. having less than 2 anal sex partners in the past 6 months ( OR =0.28,95 %CI : 0.09-0.81). Conclusions: The rate of homosexual behavior and HIV positive rate were high among MSM in Mianyang city. Homosexual behaviors after marriage were influenced by multiple factors among MSM. The motives of homosexual behavior after marriage were driven by feelings of love, the related factors were education level of senior high school or above, local residency over one year, having 10 or more friends in the MSM community and without sex pleasure with spouse. As for the motives of these behaviors was caused by releasing pressure, the related factors was having more than 2 anal sex partners.

We present the in-situ measurements in Chengdu, a major city in south west of China, in September 2016. The concentrations of ozone and its precursor were measured at four sites. Although the campaign was conducted in early autumn, up to 100 ppbv (parts per billion by volume) daily maximum ozone was often observed at all sites. The observed ozone concentrations showed good agreement at all sites, which implied that ozone pollution is a regional issue in Chengdu. To better understand the ozone formation in Chengdu, an observation based model is used in this study to calculate the RO x radical concentrations (RO x  = OH + HO 2  + RO 2 ) and ozone production rate (P(O 3 )). The model predicts OH daily maximum is in the range of 4-8 × 10 6  molecules cm -3 , and HO 2 and RO 2 are in the range of 3-6 × 10 8  molecules cm -3 . The modelled radical concentrations show a distinct difference between ozone pollution and attainment period. The relative incremental reactivity (RIR) results demonstrate that anthropogenic VOCs reduction is the most efficient way to mitigate ozone pollution at all sites, of which alkenes dominate >50% of the ozone production. Empirical kinetic modelling approach shows that three out of four sites are under the VOC-limited regime, while Pengzhou is in a transition regime due to the local petrochemical industry. The ozone budget analysis showed that the local ozone production driven by the photochemical process is important to the accumulation of ozone concentrations., (Copyright © 2018 Elsevier B.V. All rights reserved.)