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Bacterial infection has traditionally been treated with antibiotics, but their overuse is leading to the development of antibiotic resistance. This may be mitigated by alternative approaches to prevent or treat bacterial infections without utilization of antibiotics. Among the alternatives is the use of photo-responsive antimicrobial nanoparticles and/or nanocomposites, which present unique properties activated by light. In this study, we explored the combined use of titanium oxide and polydopamine to create nanoparticles with photocatalytic and photothermal antibacterial properties triggered by visible or near-infrared light. Furthermore, as a proof-of-concept, these photo-responsive nanoparticles were combined with mussel-inspired catechol-modified hyaluronic acid hydrogels to form novel light-driven antibacterial nanocomposites. The materials were challenged with models of Gram-negative and Gram-positive bacteria. For visible light, the average percentage killed (PK) was 94.6 for E. coli and 92.3 for S. aureus. For near-infrared light, PK for E. coli reported 52.8 and 99.2 for S. aureus. These results confirm the exciting potential of these nanocomposites to prevent the development of antibiotic resistance and also to open the door for further studies to optimize their composition in order to increase their bactericidal efficacy for biomedical applications.

 

The communities of Puerto Rico are highly vulnerable to climate change as the archipelago has experienced a multitude of compounding crises and extreme weather events in recent years. To address these issues, the research, analysis, and design of grand challenge solutions for disaster-prone regions like Puerto Rico can utilize collaborative transdisciplinary efforts. Local non-governmental and community-based organizations have a pivotal role in the reconstruction processes and the building of community and environmental resilience in underserved communities. This paper contributes an empirical case study of an online transdisciplinary collaboration between a group of academics and a Puerto Rican non-governmental organization, Caras con Causa. From participant observation, it includes a document analysis of meeting notes with cohort members who were involved in a collaborative National Science Foundation Project, The INFEWS-ER: A Virtual Resource Center Enabling Graduate Innovations at the Nexus of Food, Energy, and Water Systems, with Caras con Causa between October 2020 and April 2021. Caras con Causa focuses on uplifting Puerto Ricans by creating and administering environmental, educational, economic, and community programs, highlighting disaster relief and resilience to help Puerto Rican food, energy, and water systems. Eight key discussion themes emerged from the document analysis: team organization, collaboration with Caras con Causa, deliverables, team contributions, context understanding, participation outcomes, technology setup, and lessons learned. We analyze each of the emerging themes to explain how academics may use transdisciplinary skill sets in addition to standard disciplinary-based approaches or techniques to enhance the institutional capacity of a non-governmental organization doing community resilience work to benefit local food, energy, and water systems. While the learned lessons in this non-governmental organization-academic collaboration may be context-specific, we provide insights that may be generalizable to collaborations in comparable transdisciplinary settings.

 

Abstract Scientific study of issues at the nexus of food–energy–water systems (FEWS) requires grappling with multifaceted, “wicked” problems. FEWS involve interactions occurring directly and indirectly across complex and overlapping spatial and temporal scales; they are also imbued with diverse and sometimes conflicting meanings for the human and more-than-human beings that live within them. In this paper, we consider the role of language in the dynamics of boundary work, recognizing that the language often used in stakeholder and community engagement intended to address FEWS science and decision-making constructs boundaries and limits diverse and inclusive participation. In contrast, some language systems provide opportunities to build bridges rather than boundaries in engagement. Based on our experiences with engagement in FEWS science and with Indigenous knowledges and languages, we consider examples of the role of language in reflecting worldviews, values, practices, and interactions in FEWS science and engagement. We particularly focus on Indigenous knowledges from Anishinaabe and the language of Anishinaabemowin, contrasting languages of boundaries and bridges through concrete examples. These examples are used to unpack the argument of this work, which is that scientific research aiming to engage FEWS issues in working landscapes requires grappling with embedded, practical understandings. This perspective demonstrates the importance of grappling with the role of language in creating boundaries or bridges, while recognizing that training in engagement may not critically reflect on the role of language in limiting diversity and inclusivity in engagement efforts. Leaving this reflexive consideration of language unexamined may unknowingly perpetuate boundaries rather than building bridges, thus limiting the effectiveness of engagement that is intended to address wicked problems in working landscapes. 

The evolution of asymptotic giant branch stars from the spherical symmetry into the diverse shapes of planetary nebulae (PNe) is a topic of intensive research. Young PNe provide a unique opportunity to characterize the onset of this transitional phase. In particular, OH maser-emitting PNe (OHPNe) are considered nascent PNe. In fact, only six OHPNe have been confirmed to date. In order to identify and characterize more OHPNe, we processed the unpublished continuum data of the interferometric follow-up of the Southern Parkes Large-Area Survey in Hydroxyl (SPLASH). We then matched the interferometric positions of OH maser and radio continuum emission, considering the latter as a possible tracer of free–free emission from photoionized gas, characteristic of PNe. We report eight objects with a positive coincidence, four of which are classified as candidate OHPNe here for the first time (IRAS 16372–4808, IRAS 17494–2645, IRAS 18019–2216, and OH 341.6811+00.2634). Available evidence strongly indicates that they are evolved stars, while the comparison with confirmed OHPNe indicates that they are likely to be PNe. Their final confirmation as bona fide PNe, however, requires optical/infrared spectroscopy. The obtained spectral indices of the radio continuum emission (between ≃0.4–1.3) are consistent with partially optically thick free–free emission from photoionized gas. Also, they cluster in the same region of a WISE colour–colour diagram as that of the confirmed OHPNe ($9.5\lesssim[3.4]{-}[22]\lesssim13.5$, and $4.0\lesssim[4.6]{-}[12] \lesssim7.0$), thus this diagram could help to identify more OHPNe candidates in the future.

 

ABSTRACT The analysis of individual X-ray sources that appear in a crowded field can easily be compromised by the misallocation of recorded events to their originating sources. Even with a small number of sources, which none the less have overlapping point spread functions, the allocation of events to sources is a complex task that is subject to uncertainty. We develop a Bayesian method designed to sift high-energy photon events from multiple sources with overlapping point spread functions, leveraging the differences in their spatial, spectral, and temporal signatures. The method probabilistically assigns each event to a given source. Such a disentanglement allows more detailed spectral or temporal analysis to focus on the individual component in isolation, free of contamination from other sources or the background. We are also able to compute source parameters of interest like their locations, relative brightness, and background contamination, while accounting for the uncertainty in event assignments. Simulation studies that include event arrival time information demonstrate that the temporal component improves event disambiguation beyond using only spatial and spectral information. The proposed methods correctly allocate up to 65${{\ \rm per\ cent}}$ more events than the corresponding algorithms that ignore event arrival time information. We apply our methods to two stellar X-ray binaries, UV Cet and HBC 515 A, observed with Chandra. We demonstrate that our methods are capable of removing the contamination due to a strong flare on UV Cet B in its companion ≈40× weaker during that event, and that evidence for spectral variability at times-scales of a few ks can be determined in HBC 515 Aa and HBC 515 Ab.