The Solvent-Dependent Photophysics of Diphenyloctatetraene.

Despite many decades of study, the excited state photophysics of polyenes remains controversial. In diphenylpolyenes with conjugated backbones that contain between 2 and 4 double carbon-carbon bonds, the first two excited electronic states are nearly degenerate but of entirely different character, and their energy splitting is strongly dependent on solvent polarizability. To examine the interplay between these different states, steady-state and time-resolved fluorescence spectroscopies were used to undertake a comprehensive investigation of diphenylocatetraene's (DPO) excited state dynamics in 10 solvents of different polarizabilities and polarities, ranging from weakly interacting alkanes to polar hydrogen-bonding alcohols. These data revealed that photopreparation of the optically bright 1Bu state resulted in fast (<170 ps) internal conversion to the lower-lying optically dark 2Ag state. The 2Ag state is responsible for almost all the observed DPO fluorescence and gains oscillator strength via vibronic intensity stealing with the near-degenerate 1Bu state. The fluorescence lifetime associated with the 2Ag state decayed monoexponentially (4.2-7.2 ns) in contrast to prior biexponential decay kinetics reported for similar polyenes, diphenylbutadiene and diphenylhexatriene. An analysis combining the measured fluorescence lifetimes and fluorescence quantum yields (the latter varying between 7 and 21%) allowed for a 190 cm-1 Herzberg-Teller vibronic coupling constant between the 1Bu and 2Ag states to be determined. The analysis also revealed that the ordering of electronic states remains constant in all the solvents studied, with the 2Ag state minimum always lower in energy than that of the 1Bu state, thus making it a relatively simple polyene compared to structurally similar diphenylhexatriene.

Intraspecific variation in feeding and locomotor kinematics during prey capture in redbreast sunfish (Lepomis auritus).

Biomechanics research often revolves around understanding traits impacting suction feeding performance in fishes, using freshwater ray-finned sunfishes (Family Centrarchidae) as models. However, simultaneous feeding and locomotion kinematics during prey capture are not recorded for many species and there is less information on how these kinematics vary within a species and within individuals. To (1) add to existing data on the prey capture kinematics of centrarchids, (2) assess variation in a species both within and across individuals, and (3) compare morphology and prey capture kinematics of well-sampled centrarchids, we filmed five redbreast sunfish (Lepomis auritus) at 500 fps-1 approaching and striking non-evasive prey. Redbreast approach prey at ~30 cm s-1 and use approximately 70% of their maximum gape size. Traits related to feeding are more repeatable than traits related to locomotion. However, the Accuracy Index (AI) was consistent across individuals (AI = 0.76 ± 0.07). Functionally, redbreast sunfish are more similar to bluegill sunfish but morphologically they fall in the intermediate morphospace alongside green sunfish when compared with other centrarchids. These data show that whole organism outcomes (AI) are similar despite variation present both within and across individuals and demonstrate the importance of considering both interspecific and intraspecific differences in the functional diversity of ecologically and evolutionarily important behaviors such as prey capture.

It Pays to Be Bumpy: Drag Reducing Armor in the Pacific Spiny Lumpsucker, Eumicrotremus orbis.

Armor is a multipurpose set of structures that has evolved independently at least 30 times in fishes. In addition to providing protection, armor can manipulate flow, increase camouflage, and be sexually dimorphic. There are potential tradeoffs in armor function: increased impact resistance may come at the cost of maneuvering ability; and ornate armor may offer visual or protective advantages, but could incur excess drag. Pacific spiny lumpsuckers (Eumicrotremus orbis) are covered in rows of odontic, cone-shaped armor whorls, protecting the fish from wave driven impacts and the threat of predation. We are interested in measuring the effects of lumpsucker armor on the hydrodynamic forces on the fish. Bigger lumpsuckers have larger and more complex armor, which may incur a greater hydrodynamic cost. In addition to their protective armor, lumpsuckers have evolved a ventral adhesive disc, allowing them to remain stationary in their environment. We hypothesize a tradeoff between the armor and adhesion: little fish prioritize suction, while big fish prioritize protection. Using micro-CT, we compared armor volume to disc area over lumpsucker development and built 3D models to measure changes in drag over ontogeny. We found that drag and drag coefficients decrease with greater armor coverage and vary consistently with orientation. Adhesive disc area is isometric but safety factor increases with size, allowing larger fish to remain attached in higher flows than smaller fish.

Dismantling antibiotic infrastructures in residential aged care: The invisible work of antimicrobial stewardship (AMS).

Recent social science scholarship has sought to understand the visible and invisible impacts of how antibiotics are entrenched as infrastructures and put to work as a proxy for higher levels of care (clinical or otherwise) within modern healthcare. Using a qualitative research design, in this paper our aim is to draw attention to less visible aspects of antimicrobial stewardship (AMS) in residential aged care and their implications for nurse-led optimization of antibiotic use in these settings. By developing an account of the perceptions, experiences and practices of staff regarding the 'on the ground' work associated with implementing and upholding AMS objectives our study extends research on attempts to dismantle antibiotic infrastructures in Australian residential aged care facilities (RACF). Drawing on a review of relevant policies, empirical data is presented from fifty-six in-depth interviews conducted in 2021 with staff at 8 different RACFs. Interview participants included managers, nurses, and senior and junior personal care assistants. Our results suggest that registered nurses in residential aged care have been tasked with promoting antibiotic optimization and assigned with AMS responsibilities without sufficient authority and resourcing. A host of hidden care work associated with AMS strategies was evident, reinforcing some staff support for empirical antibiotic prescribing as a 'safety net' in uncertain clinical cases. We argue that this hidden work occurs where AMS strategies displace the infrastructural role previously performed by antibiotics, exposing structural gaps and pressures. The inability of organisational accounting systems and the broader AMS policy agenda to capture hidden AMS workflows in RACFs has consequences for future resourcing and organisational learning in ways that mean AMS gaps may remain unaddressed. These results support findings that AMS interventions might not be easily accepted by aged care staff in view of associated burdens which are under recognised and under supported in this domain.

Knifefish turning control and hydrodynamics during forward swimming.

Rapid turning and swimming contribute to ecologically important behaviors in fishes such as predator avoidance, prey capture, mating and the navigation of complex environments. For riverine species, such as knifefishes, turning behaviors may also be important for navigating locomotive perturbations caused by turbulent flows. Most research on fish maneuvering focuses on fish with traditional fin and body morphologies, which primarily use body bending and the pectoral fins during turning. However, it is uncertain how fishes with uncommon morphologies are able to achieve sudden and controllable turns. Here, we studied the turning performance and the turning hydrodynamics of the black ghost knifefish (Apteronotus albifrons, N=6) which has an atypical elongated ribbon fin. Fish were filmed while swimming forward at ∼2 body lengths s-1 and feeding from a fixed feeder (control) and an oscillating feeder (75 Hz) at two different amplitudes. 3D kinematic analysis of the body revealed the highest pitch angles and lowest body bending coefficients during steady swimming. Low pitch angle, high maximum yaw angles and large body bending coefficients were characteristic of small and large turns. Asynchrony in pectoral fin use was low during turning; however, ribbon fin wavelength, frequency and wave speed were greatest during large turns. Digital particle image velocimetry (DPIV) showed larger counter-rotating vortex pairs produced during turning by the ribbon fin in comparison to vortices rotating in the same direction during steady swimming. Our results highlight the ribbon fin's role in controlled rapid turning through modulation of wavelength, frequency and wave speed.

Comparing public attitudes, knowledge, beliefs and behaviours towards antibiotics and antimicrobial resistance in Australia, United Kingdom, and Sweden (2010-2021): A systematic review, meta-analysis, and comparative policy analysis.

BACKGROUND: Social and behavioural drivers of inappropriate antibiotic use contribute to antimicrobial resistance (AMR). Recent reports indicate the Australian community consumes more than twice the defined daily doses (DDD) of antibiotics per 1000 population than in Sweden, and about 20% more than in the United Kingdom (UK). We compare measures of public knowledge, attitudes and practices (KAP) surrounding AMR in Australia, the UK and Sweden against the policy approaches taken in these settings to address inappropriate antibiotic use. METHODS: National antimicrobial stewardship policies in Australia, Sweden, and the UK were reviewed, supplemented by empirical studies of their effectiveness. We searched PubMed, EMBASE, PsycINFO, Web of Science and CINAHL databases for primary studies of the general public's KAP around antibiotic use and AMR in each setting (January 1 2011 until July 30 2021). Where feasible, we meta-analysed data on the proportion of participants agreeing with identical or very similar survey questions, using a random effects model. RESULTS: Policies in Sweden enact tighter control of community antibiotic use; reducing antibiotic use through public awareness raising is not a priority. Policies in the UK and Australia are more reliant on practitioner and public education to encourage appropriate antibiotic use. 26 KAP were included in the review and 16 were meta-analysable. KAP respondents in Australia and the UK are consistently more likely to report beliefs and behaviours that are not aligned with appropriate antibiotic use, compared to participants in similar studies conducted in Sweden. CONCLUSIONS: Interactions between public knowledge, attitudes and their impacts on behaviours surrounding community use of antibiotics are complex and contingent. Despite a greater focus on raising public awareness in Australia and the UK, neither antibiotic consumption nor community knowledge and attitudes are changing significantly. Clearly public education campaigns can contribute to mitigating AMR. However, the relative success of policy approaches taken in Sweden suggests that practice level interventions may also be required to activate prescribers and the communities they serve to make substantive reductions in inappropriate antibiotic use.

Changes in the Framing of Antimicrobial Resistance in Print Media in Australia and the United Kingdom (2011-2020): A Comparative Qualitative Content and Trends Analysis.

Educating the public about antimicrobial resistance (AMR) is considered a key part of an optimal public health response. In both media depictions and policy discourses around health risks, how a problem is framed underpins public awareness and understanding, while also guiding opinions on what actions can and should be taken. Using a mixed methods approach we analyse newspaper content in Australia and the United Kingdom (UK) from 2011 to 2020 to track how causes, consequences and solutions to AMR are represented in countries with different policy approaches. Analyses demonstrate greater variability in the frames used in UK newspapers reflecting large hospital and community outbreaks and a sustained period of policy reform mid-decade. Newspapers in Australia focus more on AMR causes and consequences, highlighting the importance of scientific discovery, whereas UK coverage has greater discussion of the social and economic drivers of AMR and their associated solutions. Variations in the trends of different frames around AMR in UK newspapers indicate greater levels of public deliberation and debate around immediate and actionable solutions; whereas AMR has not had the same health and political impacts in Australia resulting in a media framing that potentially encourages greater public complacency about the issue.

Membrane protein extraction and purification using partially-esterified SMA polymers.

Styrene maleic acid (SMA) polymers have proven to be very successful for the extraction of membrane proteins, forming SMA lipid particles (SMALPs), which maintain a lipid bilayer around the membrane protein. SMALP-encapsulated membrane proteins can be used for functional and structural studies. The SMALP approach allows retention of important protein-annular lipid interactions, exerts lateral pressure, and offers greater stability than traditional detergent solubilisation. However, SMA polymer does have some limitations, including a sensitivity to divalent cations and low pH, an absorbance spectrum that overlaps with many proteins, and possible restrictions on protein conformational change. Various modified polymers have been developed to try to overcome these challenges, but no clear solution has been found. A series of partially-esterified variants of SMA (SMA 2625, SMA 1440 and SMA 17352) has previously been shown to be highly effective for solubilisation of plant and cyanobacterial thylakoid membranes. It was hypothesised that the partial esterification of maleic acid groups would increase tolerance to divalent cations. Therefore, these partially-esterified polymers were tested for the solubilisation of lipids and membrane proteins, and their tolerance to magnesium ions. It was found that all partially esterified polymers were capable of solubilising and purifying a range of membrane proteins, but the yield of protein was lower with SMA 1440, and the degree of purity was lower for both SMA 1440 and SMA 17352. SMA 2625 performed comparably to SMA 2000. SMA 1440 also showed an increased sensitivity to divalent cations. Thus, it appears the interactions between SMA and divalent cations are more complex than proposed and require further investigation.

ß-carotene oxygenase 2 deficiency-triggered mitochondrial oxidative stress promotes low-grade inflammation and metabolic dysfunction.

Low-grade inflammation is a critical pathological factor contributing to the development of metabolic disorders. ß-carotene oxygenase 2 (BCO2) was initially identified as an enzyme catalyzing carotenoids in the inner mitochondrial membrane. Mutations in BCO2 are associated with inflammation and metabolic disorders in humans, yet the underlying mechanisms remain unknown. Here, we used loss-of-function approaches in mice and cell culture models to investigate the role of BCO2 in inflammation and metabolic dysfunction. We demonstrated decreases in BCO2 mRNA and protein levels and suppression of mitochondrial respiratory complex I proteins and mitochondrial superoxide dismutase levels in the liver of type 2 diabetic human subjects. Deficiency of BCO2 caused disruption of assembly of the mitochondrial respiratory supercomplexes, such as supercomplex III2+IV in mice, and overproduction of superoxide radicals in primary mouse embryonic fibroblasts. Further, deficiency of BCO2 increased protein carbonylation and populations of natural killer cells and M1 macrophages, and decreased populations of T cells, including CD4+ and/or CD8+ in the bone marrow and white adipose tissues. Elevation of plasma inflammatory cytokines and adipose tissue hypertrophy and inflammation were also characterized in BCO2 deficient mice. Moreover, BCO2 deficient mice were more susceptible to high-fat diet-induced obesity and hyperglycemia. Double knockout of BCO2 and leptin receptor genes caused a significantly greater elevation of the fasting blood glucose level in mice at 4 weeks of age, compared to the age- and sex-matched leptin receptor knockout. Finally, administration of Mito-TEMPO, a mitochondrial specific antioxidant attenuated systemic low-grade inflammation induced by BCO2 deficiency. Collectively, these findings suggest that BCO2 is essential for mitochondrial respiration and metabolic homeostasis in mammals. Loss or decreased expression of BCO2 leads to mitochondrial oxidative stress, low-grade inflammation, and the subsequent development of metabolic disorders.

Focused Electron Beam-Induced Deposition and Post-Growth Purification Using the Heteroleptic Ru Complex (η3-C3H5)Ru(CO)3Br.

Focused electron beam-induced deposition using the heteroleptic complex (η3-C3H5)Ru(CO)3Br as a precursor resulted in deposition of material with Ru content of 23 at. %. Transmission electron microscopy images indicated a nanogranular structure of pure Ru nanocrystals, embedded into a matrix containing carbon, oxygen, and bromine. The deposits were purified by annealing in a reactive 98% N2/2% H2 atmosphere at 300 °C, resulting in a reduction of contaminants and an increase of the Ru content to 83 at. %. Although a significant volume loss of 79% was found, the shrinkage was observed mostly for vertical thickness (around 75%). The lateral dimensions decreased much less significantly (around 9%). Deposition results, in conjunction with previous gas-phase and condensed-phase surface studies on the electron-induced reactions of (η3-C3H5)Ru(CO)3Br, provide insights into the behavior of allyl, carbonyl, and bromide ligands under identical electron beam irradiation.