Asymmetric Total Synthesis of the Rearranged Steroid Phomarol Enabled by a Biomimetic SN2' Cyclization.

Phomarol is a structurally unusual 1(10 → 19)abeo-steroid with a pseudo-symmetrical cycloheptene-1,3-diol motif, an aromatic B ring, and a densely functionalized tetrahydropyran ring. Herein, we report a 13-step synthesis of this natural product from inexpensive sitolactone by means of a convergent fragment-coupling approach. Key transformations include a diastereoselective allylboration, a decarboxylative elimination, a Schönecker-Baran C-H hydroxylation, a biomimetic SN2' cyclization, and a late-stage 6π electrocyclization. Mechanistic studies indicate that the pivotal formation of the tetrahydropyran ring occurs via a silyl migration/intramolecular SN2' cyclization cascade rather than via an epoxide-opening process.

Urban greenspace helps ameliorate people's negative sentiments during the COVID-19 pandemic: The case of Beijing.

The COVID-19 pandemic has had negative effects on people's mental health worldwide, especially for those who live in large cities. Studies have reported that urban greenspace may help lessen these adverse effects, but more research that explicitly considers urban landscape pattern is needed to understand the underlying processes. Thus, this study was designed to examine whether the resident sentiments in Beijing, China changed before and during the pandemic, and to investigate what urban landscape attributes - particularly greenspace - might contribute to the sentiment changes. We conducted sentiment analysis based on 25,357 geo-tagged microblogs posted by residents in 51 neighborhoods. We then compared the resident sentiments in 2019 (before the COVID-19) with those in 2020 (during the COVID-19) using independent sample t-tests, and examined the relationship between resident sentiments and urban greenspace during the COVID-19 pandemic phases using stepwise regression. We found that residents' sentiments deteriorated significantly from 2019 to 2020 in general, and that urban sentiments during the pandemic peak times showed an urban-suburban trend that was determined either by building density or available greenspace. Although our analysis included several other environmental and socioeconomic factors, none of them showed up as a significant factor. Our study suggests the effects of urban greenspace and building density on residents' sentiments increased during the COVID-19 pandemic and that not all green spaces are equal. Increasing greenspace, especially within and near neighborhoods, seems critically important to helping urban residents to cope with public health emergencies such as global pandemics.

Green space access in the neighbourhood and childhood obesity.

Access to green space may influence individual physical activity (PA) and subsequently weight status, as increased exposure to green space could improve health by increasing opportunities and the actual levels of PA. However, whether such associations hold empirically remains inconclusive. This study reviewed articles that analysed the association between access to green space and weight-related behaviours/outcomes among children, published before 1 January 2019. The sample sizes ranged from 108 to 44 278. Four cohorts and 17 cross-sectional studies conducted in nine countries were identified. Overall, evidence showed a positive association between access to green space and PA and a negative association between access to green space and television-watching time, body mass index (BMI) and weight status among children. Distance to the nearest green space, measured by geographic information system (GIS) in 10 studies, was often used to represent access to the nearest green space. It still remains difficult to draw a clear conclusion on the association between access to green space and BMI. Longitudinal studies can directly estimate the strength of the association between exposure and disease, which is needed to determine the causal association between access to green space and weight status.

[Research progress on the differences and connections between supply and demand of urban green space]. / åŸŽå¸‚ç»¿åœ°ä¾›éœ€çš„å·®å¼‚ä¸Žè”ç³»ç ”ç©¶è¿›å±•.

As an important concept connecting urban green space (UGS) with the residents' demands, supply and demand of UGS is an important part of UGS research and planning. Identifying the difference and connection between UGS supply and demand contributes to proper configuration of UGS, human well-being improvement and urban sustainability. We reviewed literature on UGS supply and demand from 2016 to 2020, summarized common research topics and paradigms, examined associations among these topics, and proposed suggestions for future studies. We found that most studies focused on either USG supply or demand, and rarely analyzed match between UGS supply and demand. The studies of UGS supply mainly focused on the spatial and temporal patterns and the ecosystem services they provided, while the studies of demand focused on residents' subjective preference and behavior. Studies on supply and demand often differ in research objects, scales, and indicators, which was a major obstacle to construct relationships between them. We proposed that future studies should focus on the match of supply and demand. A possible way to achieve this goal is to measure UGS demand by both objective indicators and subjective preference.

High resolution temporal profiles in the Emissions Database for Global Atmospheric Research.

Emissions into the atmosphere from human activities show marked temporal variations, from inter-annual to hourly levels. The consolidated practice of calculating yearly emissions follows the same temporal allocation of the underlying annual statistics. However, yearly emissions might not reflect heavy pollution episodes, seasonal trends, or any time-dependant atmospheric process. This study develops high-time resolution profiles for air pollutants and greenhouse gases co- emitted by anthropogenic sources in support of atmospheric modelling, Earth observation communities and decision makers. The key novelties of the Emissions Database for Global Atmospheric Research (EDGAR) temporal profiles are the development of (i) country/region- and sector- specific yearly profiles for all sources, (ii) time dependent yearly profiles for sources with inter-annual variability of their seasonal pattern, (iii) country- specific weekly and daily profiles to represent hourly emissions, (iv) a flexible system to compute hourly emissions including input from different users. This work creates a harmonized emission temporal distribution to be applied to any emission database as input for atmospheric models, thus promoting homogeneity in inter-comparison exercises.

[Research progress on relationship between urban greenspace distribution and the socioeconomic characteristics of residents]. / åŸŽå¸‚ç»¿åœ°æ ¼å±€ä¸Žå± æ°‘ç¤¾ä¼šç»æµŽç‰¹å¾å ³ç³»ç ”ç©¶è¿›å±•.

Urban greenspace, which serves as a place for residents to connect with nature and relax, provides important ecosystem services. Access to greenspace is often related to the socio-economic characteristics of residents, which received a lot attention from researchers and practitioners. Previous studies have mostly focused on single city to analyze the spatial relationship between greenspace distribution and residents' characteristics. We conducted a meta-analysis with global studies. The objectives were to classify findings from different cases and investigate the impacts from the location of research area, indicator and analytical method, and summarized major factors influen-cing the relationship between greenspace distribution and residents' characteristics. The results showed that more than half of the cases (58.2%) found that the socially advantaged population benefited more from greenspace. About a quarter cases (25.4%) revealed the opposite, that was, the disadvantaged population benefited more from greenspace. The remaining case studies (16.4%) did not find significant correlation between them. The studies reviewed here were diverse in terms of scale, indicator selection, and analytical method. Overall, we found no connection between finding and the choice of scale/indicator/analytical method. The reviewed case studies were mostly conducted in cities of western countries, which differed in their development trajectories and urban characteristics from cities in China. To understand association between urban greenspace and residents' characteristics in China, we urged to carry out more local studies, which would potentially provide scientific evidence for building sustainable cities during rapid urbanization.

Breathing the same air? Socioeconomic disparities in PM2.5 exposure and the potential benefits from air filtration.

Air pollution caused by particulate matter <2.5 µm in diameter (PM2.5) imposes a severe health burden to people worldwide. Across the globe, and even within cities, the health burden of air pollution is not equally shared by citizens. Despite being the region suffering from the most severe air pollution, studies examining the inequity of the burdens of air pollution in Asia are limited. We aim to fill in this gap by analyzing the relationship between PM2.5 pollution and residents' socioeconomic characteristics in Beijing, the icon city for PM2.5 pollution. Our results show that household income and education were negatively correlated with ambient air quality (r = -0.62; p < 0.05 and r = -0.73; p < 0.01 respectively) in 2014. We found in Beijing air quality is worse where residents have less income and lower education rates and are less capable to protect themselves from the potential health risk. To counter the effects of air pollution in Beijing, air filtration has been shown to be an effective means to reduce, at least, indoor PM2.5 levels. We illustrate through a simple scenario analysis that air filtration can reduce exposure (26-79%) to a similar extent as the structural mitigation programs (e.g. closing coal factories) achieved in recent years (53%). We argue government intervention is needed to convey the benefit of air filtration to the socioeconomically disadvantaged groups.

Public Perception of Extreme Cold Weather-Related Health Risk in a Cold Area of Northeast China.

OBJECTIVE: A need exists for public health strategies regarding extreme weather disasters, which in recent years have become more frequent. This study aimed to understand the public's perception of extreme cold and its related health risks, which may provide detailed information for public health preparedness during an extreme cold weather event. METHODS: To evaluate public perceptions of cold-related health risk and to identify vulnerable groups, we collected responses from 891 participants in a face-to-face survey in Harbin, China. Public perception was measured by calculating the score for each perception question. RESULTS: Locals perceived that extreme cold weather and related health risks were serious, but thought they could not avoid these risks. The significant difference in perceived acceptance level between age groups suggested that the elderly are a "high health risk, low risk perception" group, meaning that they are relatively more vulnerable owing to their high susceptibility and low awareness of the health risks associated with extreme cold weather. CONCLUSIONS: The elderly should be a priority in risk communication and health protective interventions. This study demonstrated that introducing risk perception into the public health field can identify vulnerable groups with greater needs, which may improve the decision-making of public health intervention strategies. (Disaster Med Public Health Preparedness. 2017;11:417-421).

Public health impacts of city policies to reduce climate change: findings from the URGENCHE EU-China project.

BACKGROUND: Climate change is a global threat to health and wellbeing. Here we provide findings of an international research project investigating the health and wellbeing impacts of policies to reduce greenhouse gas emissions in urban environments. METHODS: Five European and two Chinese city authorities and partner academic organisations formed the project consortium. The methodology involved modelling the impact of adopted urban climate-change mitigation transport, buildings and energy policy scenarios, usually for the year 2020 and comparing them with business as usual (BAU) scenarios (where policies had not been adopted). Carbon dioxide emissions, health impacting exposures (air pollution, noise and physical activity), health (cardiovascular, respiratory, cancer and leukaemia) and wellbeing (including noise related wellbeing, overall wellbeing, economic wellbeing and inequalities) were modelled. The scenarios were developed from corresponding known levels in 2010 and pre-existing exposure response functions. Additionally there were literature reviews, three longitudinal observational studies and two cross sectional surveys. RESULTS: There are four key findings. Firstly introduction of electric cars may confer some small health benefits but it would be unwise for a city to invest in electric vehicles unless their power generation fuel mix generates fewer emissions than petrol and diesel. Second, adopting policies to reduce private car use may have benefits for carbon dioxide reduction and positive health impacts through reduced noise and increased physical activity. Third, the benefits of carbon dioxide reduction from increasing housing efficiency are likely to be minor and co-benefits for health and wellbeing are dependent on good air exchange. Fourthly, although heating dwellings by in-home biomass burning may reduce carbon dioxide emissions, consequences for health and wellbeing were negative with the technology in use in the cities studied. CONCLUSIONS: The climate-change reduction policies reduced CO2 emissions (the most common greenhouse gas) from cities but impact on global emissions of CO2 would be more limited due to some displacement of emissions. The health and wellbeing impacts varied and were often limited reflecting existing relatively high quality of life and environmental standards in most of the participating cities; the greatest potential for future health benefit occurs in less developed or developing countries.

[Urban ecosystem services: A review].

Maintaining and improving ecosystem services in urban areas and human well-being are essential for sustainable development and therefore constitute an important topic in urban ecology. Here we reviewed studies on ecosystem services in urban areas. Based on the concept and classification of urban ecosystem services, we summarized characteristics of urban ecosystem services, including the human domination, high demand of ecosystem services in urban areas, spatial heterogeneity and temporal dynamics of ecosystem services supply and demand in urban areas, multi-services of urban green infrastructures, the socio-economic dimension of ecosystem services supply and ecosystem disservices in urban areas. Among different urban ecosystem services, the regulating service and cultural service are particularly indispensable to benefit human health. We pointed out that tradeoffs among different types of ecosystem services mostly occur between supportive service and cultural service, as well as regulating service and cultural service. In particular, we emphasized the relationship between landscape design (i.e. green infrastructure) and ecosystem services supply. Finally, we discussed current gaps to link urban ecosystem services studies to landscape design and management and pointed out several directions for future research in urban ecosystem services.