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We present city specific climate action policy recommendations for urban practitioners, government officers, city leaders, and research decision-makers, from the recently released City Research and Innovation Agenda (CRIA). Building on the Global Research Action Agenda for Cities Climate Change Science 2018, updated in 2021—key outputs from the first Cities and Climate Change Science Conference in Edmonton 2018 and the follow up Innovate4Cities 2021 Conference (online)—the CRIA presents the priority city research and policy gaps identified at these two major conferences. With a focus on the nexus of cities, climate change science, and policy innovation, the CRIA is for policy and decision-makers looking to make significant progress on city focused climate action strategies and plans, by focusing their attention on the city-relevant evidence and outcome-oriented partnerships needed across academia, government, business, and civil society. Here, we provide a summary of the CRIA, that presents priorities under four key questions that cities and their partners in research and innovation ask as they develop and implement climate plans: How do we build the evidence base for climate action? How and for whom should we prioritize? What should we do? and How do we finance and scale climate action? We include arguments for why consolidated understanding of data, technology, and knowledge gaps across a city climate action journey is important to accelerate implementation of cities’ climate commitments, as is the need for key partnerships to support cities in meeting climate goals.

To meet the targets of the Paris Climate Agreement, municipalities must facilitate transformational change at a local level. From a city perspective, the climate crisis intersects with many other complex challenges; therefore, transformational change should be coordinated in a purposeful and holistic way for it to address multiple challenges effectively, and to improve the lives of all citizens. This necessitates a change in the mindsets of municipal leaders, along with a systemic way of approaching strategic management. This article leverages an interdisciplinary lens based on social systems theory, combining management, science, and psychology to derive conclusions for transformative action. The authors draw from their experience facilitating change within municipalities to illustrate key points. This article derives recommendations for policymakers and research recommendations based on the view of the city as a complex system. At an organizational level, cities need to develop strategies that represent the diversity of its citizens and integrates localized social, environmental, and economic goals. At an individual level, city leaders and staff need to develop three kinds of knowledge: system knowledge, transformation knowledge, and action-guiding visions. The diversity and complexity of challenges that must be overcome for cities to become sustainable, just, and resilient requires a shift in the mindsets of city leaders and other stakeholders as well as the transformation of strategic management practices. Currently, there is a lack of accessible and practical evidence-based solutions available to municipal leaders to support facilitating this change. The authors call for research and clear recommendations on how to work toward closing this gap.

By 2030, an additional 1.2 billion people are forecast in urban areas globally. We review the scientific literature (n = 922 studies) to assess direct and indirect impacts of urban growth on habitat and biodiversity. Direct impacts are cumulatively substantial, with 290,000 km2 of natural habitat forecast to be converted to urban land uses between 2000 and 2030. Studies of direct impact are disproportionately from high-income countries. Indirect urban impacts on biodiversity, such as food consumption, affect a greater area than direct impacts, but comparatively few studies (34%) have quantified urban indirect impacts on biodiversity. The world is urbanizing. This Review assesses impacts of urban growth on habitat and biodiversity, finding direct impacts more in high-income countries while indirect impacts affect more land but are lesser studied.

Networks are increasingly important for advancing urban science, policy and practice. The complexity that cities present to stakeholders of all kinds demands systems-based and networked approaches to solving sustainability challenges. This article analyses the contemporary rise of global networks of urban science, policy, and practice. We provide an overview of urban science, policy, and practice networks followed by a detailed case study of the emerging Future Earth Urban Knowledge Action Network (Urban KAN), highlighting its vision, initial activities and impacts, and challenges and remaining tasks. Findings from the case study reveal that a network across science, policy and practice can make significant contribution in cutting-edge knowledge generation, global research agenda setting, timely contribution to global policy processes, catalyzing the formation of new national and thematic research-action networks, among others. In contrast, such a network also faces challenges, in terms of attraction and representation of the composition, maintaining initial momentum, turning the science-policy integration and collaboration into reality, and obtaining strong and continued financial and institutional support. We conclude that networks across the boundaries of science-policy-practice are still in their infancy, and deeper collaborations across sector, scale, and networks that enable the implementation of effective new actions will be key indicator in measuring the success of these networks.

Hydra amphiphiles mimic the morphology of the mythical multi-headed creatures for which they are named. Likewise, when faced with a pathogenic bacterium, some hydra derivatives are as destructive as their fabled counterparts were to their adversaries. This report focuses on eight new tricephalic (triple-headed), single-tailed amphiphiles. Each amphiphile has a mesitylene (1,3,5-trimethylbenzene) core, two benzylic trimethylammonium groups and one dimethylalkylammonium group with a linear hydrophobe ranging from short (C8H17) to ultralong (C22H45). The logarithm of the critical aggregation concentration, log(CAC), decreases linearly with increasing tail length, but with a smaller dependence than that of ionic amphiphiles with fewer head groups. Tail length also affects antibacterial activity; amphiphiles with a linear 18 or 20 carbon atom hydrophobic chain are more effective at killing bacteria than those with shorter or longer chains. Comparison to a recently reported amphiphilic series with three heads and two tails allows for the development of an understanding of the relationship between number of tails and both colloidal and antibacterial properties.

Globally consistent measurements of airborne metal concentrations in fine particulate matter (PM2.5) are important for understanding potential health impacts, prioritizing air pollution mitigation strategies, and enabling global chemical transport model development. PM2.5 filter samples (N ~ 800 from 19 locations) collected from a globally distributed surface particulate matter sampling network (SPARTAN) between January 2013 and April 2019 were analyzed for particulate mass and trace metals content. Metal concentrations exhibited pronounced spatial variation, primarily driven by anthropogenic activities. PM2.5 levels of lead, arsenic, chromium, and zinc were significantly enriched at some locations by factors of 100–3000 compared to crustal concentrations. Levels of metals in PM2.5 and PM10 exceeded health guidelines at multiple sites. For example, Dhaka and Kanpur sites exceeded the US National Ambient Air 3-month Quality Standard for lead (150 ng m−3). Kanpur, Hanoi, Beijing and Dhaka sites had annual mean arsenic concentrations that approached or exceeded the World Health Organization’s risk level for arsenic (6.6 ng m−3). The high concentrations of several potentially harmful metals in densely populated cites worldwide motivates expanded measurements and analyses.

Two novel series of tris-cationic, tripled-headed, double-tailed amphiphiles were synthesized and the effects of tail length and head group composition on the critical aggregation concentration (CAC), thermodynamic parameters, and minimum inhibitory concentration (MIC) against six bacterial strains were investigated. Synergistic antibacterial combinations of these amphiphiles were also identified. Amphiphiles in this study are composed of a benzene core with three benzylic ammonium bromide groups, two of which have alkyl chains, each 8-16 carbons in length. The third head group is a trimethylammonium or pyridinium. Log of critical aggregation concentration (log[CAC]) and heat of aggregation (ΔHagg) were both inversely proportional to the length of the linear hydrocarbon chains. Antibacterial activity increases with tail length until an optimal tail length of 12 carbons per chain, above which, activity decreased. The derivatives with two 12 carbon chains had the best antibacterial activity, killing all tested strains at concentrations of 1-2μM for Gram-positive and 4-16μM for Gram-negative bacteria. The identity of the third head group (trimethylammonium or pyridinium) had minimal effect on colloidal and antibacterial activity. The antibacterial activity of several binary combinations of amphiphiles from this study was higher than activity of individual amphiphiles, indicating that these combinations are synergistic. These amphiphiles show promise as novel antibacterial agents that could be used in a variety of applications.

Treatment of toyocamycin or sangivamycin with 1,3-dibromo-5,5-dimethylhydantoin in MeOH (r.t./30 min) gave 8-bromotoyocamycin and 8-bromosangivamycin in good yields. Nucleophilic aromatic substitution of 8-bromotoyocamycin with sodium azide provided novel 8-azidotoyocamycin. Strain promoted click reactions of the latter with cyclooctynes resulted in the formation of the 1,2,3-triazole products. Iodine-mediated direct C8-H bond functionalization of tubercidin with benzotriazoles in the presence of tert-butyl hydroperoxide gave the corresponding 8-benzotriazolyltubercidin derivatives. The 8-(1,2,3-triazol-1-yl)-7-deazapurine derivatives showed moderate quantum yields and a large Stokes shifts of ~ 100 nm.