Investigation of N-Substituted Morpholine Structures in an Amphiphilic PDMS-Based Antifouling and Fouling-Release Coating.

Biofouling is a major disruptive process affecting the fuel efficiency and durability of maritime vessel coatings. Previous research has shown that amphiphilic coatings consisting of a siloxane backbone functionalized with hydrophilic moieties are effective marine antifouling and fouling-release materials. Poly(ethylene glycol) (PEG) has been the primary hydrophilic component used in such systems. Recently, the morpholine group has emerged as a promising compact alternative in antifouling membranes but is yet to be studied against marine foulants. In this work, the use of morpholine moieties to generate amphiphilicity in a poly(dimethylsiloxane) (PDMS)-based antifouling and fouling-release coating was explored. Two separate coating sets were investigated. The first set examined the incorporation of an N-substituted morpholine amine, and while these coatings showed promising fouling-release properties for Ulva linza, they had unusually high settlement of spores compared to controls. Based on those results, a second set of materials was synthesized using an N-substituted morpholine amide to probe the source of the high settlement and was found to significantly improve antifouling performance. Both coating sets included PEG controls with varying lengths to compare the viability of the morpholine structures as alternative hydrophilic groups. Surfaces were evaluated through a combination of bubble contact angle goniometry, profilometry, X-ray photoelectron spectroscopy (XPS), and marine bioassays against two soft fouling species, U. linza and Navicula incerta, known to have different adhesion characteristics.

Low Fouling Polysulfobetaines with Variable Hydrophobic Content.

Amphiphilic polymer coatings combining hydrophilic elements, in particular zwitterionic groups, and hydrophobic elements comprise a promising strategy to decrease biofouling. However, the influence of the content of the hydrophobic component in zwitterionic coatings on the interfacial molecular reorganization dynamics and the anti-fouling performance is not well understood. Therefore, coatings of amphiphilic copolymers of sulfobetaine methacrylate 3-[N-2'-(methacryloyloxy)ethyl-N,N-dimethyl]-ammonio propane-1-sulfonate (SPE) are prepared which contain increasing amounts of hydrophobic n-butyl methacrylate (BMA). Their fouling resistance is compared to that of their homopolymers PSPE and PBMA. The photo-crosslinked coatings form hydrogel films with a hydrophilic surface. Fouling by the proteins fibrinogen and lysozyme as well as by the diatom Navicula perminuta and the green algae Ulva linza is assessed in laboratory assays. While biofouling is strongly reduced by all zwitterionic coatings, the best fouling resistance is obtained for the amphiphilic copolymers. Also in preliminary field tests, the anti-fouling performance of the amphiphilic copolymer films is superior to that of both homopolymers. When the coatings are exposed to a marine environment, the reduced susceptibility to silt incorporation, in particular compared to the most hydrophilic polyzwitterion PSPE, likely contributes to the improved fouling resistance.

Barriers and enablers faced by regional and rural schools in supporting student mental health: A mixed-methods systematic review.

BACKGROUND: Australian policy reports recommended schools to be leveraged to better support student mental health, with a focus on regional and rural areas where students have poorer mental health outcomes. In designing solutions to address this systemic gap, decision-makers require an understanding of the barriers and facilitators experienced by regional and rural schools. However, current literature has focused on metropolitan schools and neglected to explore facilitators. OBJECTIVE: To review the evidence on barriers and facilitators in delivering student mental health support experienced by regional and rural schools in Organisation for Economic Co-operation and Development nations. DESIGN: A mixed-methods systematic review of peer-reviewed and grey literature. FINDINGS: The search identified 4819 studies. A full-text review by 2 reviewers resulted in 5 papers, which met the inclusion criteria and were assessed using methodological appraisal. One study used qualitative data, 2 studies used quantitative data, and 2 studies were a mixed-methods design. DISCUSSION: While there was a paucity of studies, this review draws together the most up-to-date research. The barriers and facilitators were categorised into 3 themes: access to services and resources; mental health literacy of staff and parents; and communication and collaboration between stakeholders. CONCLUSION: This review presents a comprehensive synthesis of the literature and highlights opportunities to leverage rural and regional schools to support student mental health, focusing on the quality of communication and collaboration, and increasing access to services and resources, and mental health literacy. Research should explore the unique advantages of rural and regional areas to inform policy, including a focus on strengths.

Amphiphilic Nitroxide-Bearing Siloxane-Based Block Copolymer Coatings for Enhanced Marine Fouling Release.

The buildup of organic matter and organisms on surfaces exposed to marine environments, known as biofouling, is a disruptive and costly process affecting maritime operations. Previous research has identified some of the surface characteristics particularly suited to the creation of antifouling and fouling-release surfaces, but there remains room for improvement against both macrofouling and microfouling organisms. Characterization of their adhesives has shown that many rely on oxidative chemistries. In this work, we explore the incorporation of the stable radical 2,2,6,6-tetramethylpipiderin-1-oxyl (TEMPO) as a component in an amphiphilic block copolymer system to act as an inhibitor for marine cements, disrupting adhesion of macrofouling organisms. Using polystyrene-b-poly(dimethylsiloxane-r-vinylmethysiloxane) block copolymers, pendent vinyl groups were functionalized with TEMPO and poly(ethylene glycol) to construct an amphiphilic material with redox active character. The antifouling and fouling-release performance of these materials was investigated through settlement and removal assays of three model fouling organisms and correlated to surface structure and chemistry. Surfaces showed significant antifouling character and fouling-release performance was increased substantially toward barnacles by the incorporation of stable radicals, indicating their potential for marine antifouling applications.

Omics-based molecular analyses of adhesion by aquatic invertebrates.

Many aquatic invertebrates are associated with surfaces, using adhesives to attach to the substratum for locomotion, prey capture, reproduction, building or defence. Their intriguing and sophisticated biological glues have been the focus of study for decades. In all but a couple of specific taxa, however, the precise mechanisms by which the bioadhesives stick to surfaces underwater and (in many cases) harden have proved to be elusive. Since the bulk components are known to be based on proteins in most organisms, the opportunities provided by advancing 'omics technologies have revolutionised bioadhesion research. Time-consuming isolation and analysis of single molecules has been either replaced or augmented by the generation of massive data sets that describe the organism's translated genes and proteins. While these new approaches have provided resources and opportunities that have enabled physiological insights and taxonomic comparisons that were not previously possible, they do not provide the complete picture and continued multi-disciplinarity is essential. This review covers the various ways in which 'omics have contributed to our understanding of adhesion by aquatic invertebrates, with new data to illustrate key points. The associated challenges are highlighted and priorities are suggested for future research.

Pollen Source Richness May Be a Poor Predictor of Bumblebee (Bombus terrestris) Colony Growth.

Agricultural intensification has drastically altered foraging landscapes for bees, with large-scale crop monocultures associated with floral diversity loss. Research on bumblebees and honeybees has shown individuals feeding on pollen from a low richness of floral sources can experience negative impacts on health and longevity relative to higher pollen source richness of similar protein concentrations. Florally rich landscapes are thus generally assumed to better support social bees. Yet, little is known about whether the effects of reduced pollen source richness can be mitigated by feeding on pollen with higher crude protein concentration, and importantly how variation in diet affects whole colony growth, rearing decisions and sexual production. Studying queen-right bumblebee (Bombus terrestris) colonies, we monitored colony development under a polyfloral pollen diet or a monofloral pollen diet with 1.5-1.8 times higher crude protein concentration. Over 6 weeks, we found monofloral colonies performed better for all measures, with no apparent long-term effects on colony mass or worker production, and a higher number of pupae in monofloral colonies at the end of the experiment. Unexpectedly, polyfloral colonies showed higher mortality, and little evidence of any strategy to counteract the effects of reduced protein; with fewer and lower mass workers being reared, and males showing a similar trend. Our findings (i) provide well-needed daily growth dynamics of queenright colonies under varied diets, and (ii) support the view that pollen protein content in the foraging landscape rather than floral species richness per se is likely a key driver of colony health and success.

Degradable hyaluronic acid/chitosan polyelectrolyte multilayers with marine fouling-release properties.

Polysaccharide multilayers consisting of hyaluronic acid and chitosan were prepared by layer-by-layer assembly. To be used in seawater, the multilayers were crosslinked to a different degree using thermal or chemical methods. ATR-FTIR revealed different amide densities as a result of the crosslinking conditions. AFM showed that the crosslinking affected the roughness and swelling behavior of the coatings. The stability and degradability of the multilayers in aqueous environments were monitored with spectroscopic ellipsometry. The resistance of the coatings against non-specific protein adsorption was characterized by SPR spectroscopy. Settlement assays using Ulva linza zoospores and removal assays using the diatom Navicula incerta showed that the slowly degradable coatings were less prone to fouling than the strongly crosslinked ones. Thus, the coatings were a suitable model system to show that crosslinking the multilayers under mild conditions and equipping the coatings with controlled degradation rates enhances their antifouling and fouling-release properties against marine fouling organisms.

Sol-Gel-Based Hybrid Materials as Antifouling and Fouling-Release Coatings for Marine Applications.

Hybrid materials (HMs) offer unique properties as they combine inorganic and organic components into a single material. Here, we developed HM coatings for marine antifouling applications using sol-gel chemistry and naturally occurring polysaccharides. The coatings were characterized by spectroscopic ellipsometry, contact angle goniometry, AFM, and ATR-FTIR, and their stability was tested in saline media. Marine antifouling and fouling-release properties were tested in laboratory assays against the settlement of larvae of the barnacle Balanus improvisus and against the settlement and removal of the diatom Navicula incerta. Furthermore, laboratory data were confirmed in short-term dynamic field assays in Florida, USA. All hybrid coatings revealed a superior performance in the assays compared to a hydrophobic reference. Within the hybrids, those with the highest degree of hydrophilicity and negative net charge across the surface performed best. Alginate and heparin showed good performance, making these hybrid materials promising building blocks for fouling-resistant coatings.

Effect of Dipole Orientation in Mixed, Charge-Equilibrated Self-assembled Monolayers on Protein Adsorption and Marine Biofouling.

While zwitterionic interfaces are known for their excellent low-fouling properties, the underlying molecular principles are still under debate. In particular, the role of the zwitterion orientation at the interface has been discussed recently. For elucidation of the effect of this parameter, self-assembled monolayers (SAMs) on gold were prepared from stoichiometric mixtures of oppositely charged alkyl thiols bearing either a quaternary ammonium or a carboxylate moiety. The alkyl chain length of the cationic component (11-mercaptoundecyl)-N,N,N-trimethylammonium, which controls the distance of the positively charged end group from the substrate's surface, was kept constant. In contrast, the anionic component and, correspondingly, the distance of the negatively charged carboxylate groups from the surface was varied by changing the alkyl chain length in the thiol molecules from 7 (8-mercaptooctanoic acid) to 11 (12-mercaptododecanoic acid) to 15 (16-mercaptohexadecanoic acid). In this way, the charge neutrality of the coating was maintained, but the charged groups exposed at the interface to water were varied, and thus, the orientation of the dipoles in the SAMs was altered. In model biofouling studies, protein adsorption, diatom accumulation, and the settlement of zoospores were all affected by the altered charge distribution. This demonstrates the importance of the dipole orientation in mixed-charged SAMs for their inertness to nonspecific protein adsorption and the accumulation of marine organisms. Overall, biofouling was lowest when both the anionic and the cationic groups were placed at the same distance from the substrate's surface.

Antifouling Properties of Dendritic Polyglycerols against Marine Macrofouling Organisms.

Dendritic polyglycerols (PGs) were synthesized and postmodified by grafting of poly(ethylene glycol) (PEG) and polypropylene glycol (PPG) diglycidyl ether groups, and their antifouling and fouling-release properties were tested. Coating characterization by spectroscopic ellipsometry, contact angle goniometry, attenuated total internal reflection-Fourier transform infrared spectroscopy (ATR-FTIR), and atomic force microscopy showed brushlike morphologies with a high degree of microscale roughness and the ability to absorb large amounts of water within seconds. PGs with three different thicknesses were tested in laboratory assays against settlement of larvae of the barnacle Balanus improvisus and against the settlement and removal of zoospores of the alga Ulva linza. Very low coating thicknesses, e.g., 11 nm, reduced the settlement of barnacles, under static conditions, to 2% compared with 55% for an octadecyltrichlorosilane reference surface. In contrast, zoospores of U. linza settled readily but the vast majority were removed by exposure to a shear force of 52 Pa. Both PEG and PPG modification increased the antifouling properties of the PG films, providing a direct comparison of the ultralow fouling properties of all three polymers. Both, the modified and the nonmodified PGs are promising components for incorporation into amphiphilic fouling-resistant coatings.

Layer-by-layer constructed hyaluronic acid/chitosan multilayers as antifouling and fouling-release coatings.

Polyelectrolyte multilayers (PEMs) consisting of hyaluronic acid (HA) and chitosan (Ch) are extensively studied for biomedical applications and suppress bacterial and protein attachment. Here, we prepared and tested HA/Ch PEMs as marine fouling-release coatings. PEMs were constructed by layer-by-layer assembly using spin coating. The multilayers were crosslinked for enhanced stability in the sea water environment by chemical and thermal treatment. Protein-repelling properties of the crosslinked multilayers were investigated by surface plasmon resonance spectroscopy. The marine antifouling and fouling-release properties were tested against the settlement of zoospores of the green alga Ulva linza and the subsequent development and removal of sporelings. With spin coating and thermal crosslinking, a thick yet homogeneous coating was obtained with antifouling properties against marine algal zoospores indicating the potential of these compounds for application in protective coatings.

Transcriptional characterisation of the Exaiptasia pallida pedal disc.

BACKGROUND: Biological adhesion (bioadhesion), enables organisms to attach to surfaces as well as to a range of other targets. Bioadhesion evolved numerous times independently and is ubiquitous throughout the kingdoms of life. To date, investigations have focussed on various taxa of animals, plants and bacteria, but the fundamental processes underlying bioadhesion and the degree of conservation in different biological systems remain poorly understood. This study had two aims: 1) To characterise tissue-specific gene regulation in the pedal disc of the model cnidarian Exaiptasia pallida, and 2) to elucidate putative genes involved in pedal disc adhesion. RESULTS: Five hundred and forty-seven genes were differentially expressed in the pedal disc compared to the rest of the animal. Four hundred and twenty-seven genes were significantly upregulated and 120 genes were significantly downregulated. Forty-one condensed gene ontology terms and 19 protein superfamily classifications were enriched in the pedal disc. Eight condensed gene ontology terms and 11 protein superfamily classifications were depleted. Enriched superfamilies were consistent with classifications identified previously as important for the bioadhesion of unrelated marine invertebrates. A host of genes involved in regulation of extracellular matrix generation and degradation were identified, as well as others related to development and immunity. Ab initio prediction identified 173 upregulated genes that putatively code for extracellularly secreted proteins. CONCLUSION: The analytical workflow facilitated identification of genes putatively involved in adhesion, immunity, defence and development of the E. pallida pedal disc. When defence, immunity and development-related genes were identified, those remaining corresponded most closely to formation of the extracellular matrix (ECM), implicating ECM in the adhesion of anemones to surfaces. This study therefore provides a valuable high-throughput resource for the bioadhesion community and lays a foundation for further targeted research to elucidate bioadhesion in the Cnidaria.

Low-Fouling Thin Hydrogel Coatings Made of Photo-Cross-Linked Polyzwitterions.

Although zwitterionic chemistries are among the most promising materials for producing nonfouling surfaces, their structural diversity has been low until now. Here, we compare the in vitro fouling behavior of a set of four systematically varied sulfa-/sulfobetaine-containing zwitterionic hydrogel coatings against a series of proteins and nonmotile as well as motile marine organisms as model foulers. The coatings are prepared by simultaneous photoinduced cross-linking and surface anchoring to elucidate the effect of the molecular structure of the zwitterionic moieties on their antifouling activity. Analogously prepared coatings of poly(butyl methacrylate) and poly(oligoethylene glycol methacrylate) serve as references. Photoreactive polymers are synthesized by the statistical copolymerization of sulfobetaine or sulfabetaine methacrylates and methacrylamides with a benzophenone derivative of 2-hydroxyethyl methacrylate and are applied as a thin film coating. While keeping the density of the zwitterionic and cross-linker groups constant, the molecular structure of the zwitterionic side chains is varied systematically, as is the arrangement of the ion pairs in the side chain by changing the classical linear geometry to a novel Y-shaped geometry. All of the polyzwitterions strongly reduce fouling compared to poly(butyl methacrylate). Overall, the sulfabetaine polyzwitterion coatings studied matches the high antifouling effectiveness of oligo(ethylene glycol)-based ones used as a control. Nevertheless, performances varied individually for a given pair of polymer and fouler. The case of the polysulfobetaines exemplifies that minor chemical changes in the polymer structure affect the antifouling performance markedly. Accordingly, the antifouling performance of such polymers cannot be correlated simply to the type of zwitterion used (which could be generally ranked as better performing or poorer performing) but is a result of the polymer's precise chemical structure. Our findings underline the need to enlarge the existing structural diversity of polyzwitterions for antifouling purposes to optimize the potential of their chemical structure.

Increased Ca buffering underpins remodelling of Ca2+ handling in old sheep atrial myocytes.

KEY POINTS: Ageing is associated with an increased risk of cardiovascular disease and arrhythmias, with the most common arrhythmia being found in the atria of the heart. Little is known about how the normal atria of the heart remodel with age and thus why dysfunction might occur. We report alterations to the atrial systolic Ca2+ transient that have implications for the function of the atrial in the elderly. We describe a novel mechanism by which increased Ca buffering can account for changes to systolic Ca2+ in the old atria. The present study helps us to understand how the processes regulating atrial contraction are remodelled during ageing and provides a basis for future work aiming to understand why dysfunction develops. ABSTRACT: Many cardiovascular diseases, including those affecting the atria, are associated with advancing age. Arrhythmias, including those in the atria, can arise as a result of electrical remodelling or alterations in Ca2+ homeostasis. In the atria, age-associated changes in the action potential have been documented. However, little is known about remodelling of intracellular Ca2+ homeostasis in the healthy aged atria. Using single atrial myocytes from young and old Welsh Mountain sheep, we show the free Ca2+ transient amplitude and rate of decay of systolic Ca2+ decrease with age, whereas sarcoplasmic reticulum (SR) Ca content increases. An increase in intracellular Ca buffering explains both the decrease in Ca2+ transient amplitude and decay kinetics in the absence of any change in sarcoendoplasmic reticulum calcium transport ATPase function. Ageing maintained the integrated Ca2+ influx via ICa-L but decreased peak ICa-L . Decreased peak ICa-L was found to be responsible for the age-associated increase in SR Ca content but not the decrease in Ca2+ transient amplitude. Instead, decreased peak ICa-L offsets increased SR load such that Ca2+ release from the SR was maintained during ageing. The results of the present study highlight a novel mechanism by which increased Ca buffering decreases systolic Ca2+ in old atria. Furthermore, for the first time, we have shown that SR Ca content is increased in old atrial myocytes.

Generics license 30-month-olds' inferences about the atypical properties of novel kinds.

We examined whether the distinction between generic and nongeneric language provides toddlers with a rapid and efficient means to learn about kinds. In Experiment 1, we examined 30-month-olds' willingness to extend atypical properties to members of an unfamiliar category when the properties were introduced in 1 of 3 ways: (a) using a generic noun phrase ("Blicks drink ketchup"); (b) using a nongeneric noun phrase ("These blicks drink ketchup"); and (c) using an attentional phrase ("Look at this"). Hearing a generic noun phrase boosted toddlers' extension of properties to both the model exemplars and to novel members of the same category, relative to when a property had been introduced with a nongeneric noun phrase or an attentional phrase. In Experiment 2, properties were introduced with a generic noun phrase, and toddlers extended novel properties to members of the same-category, but not to an out-of-category object. Taken together, these findings demonstrate that generics highlight the stability of a feature and foster generalization of the property to novel within-category exemplars. (PsycINFO Database Record

Perturbed atrial calcium handling in an ovine model of heart failure: potential roles for reductions in the L-type calcium current.

Heart failure (HF) is commonly associated with reduced cardiac output and an increased risk of atrial arrhythmias particularly during ß-adrenergic stimulation. The aim of the present study was to determine how HF alters systolic Ca(2+) and the response to ß-adrenergic (ß-AR) stimulation in atrial myocytes. HF was induced in sheep by ventricular tachypacing and changes in intracellular Ca(2+) concentration studied in single left atrial myocytes under voltage and current clamp conditions. The following were all reduced in HF atrial myocytes; Ca(2+) transient amplitude (by 46% in current clamped and 28% in voltage clamped cells), SR dependent rate of Ca(2+) removal (kSR, by 32%), L-type Ca(2+) current density (by 36%) and action potential duration (APD90 by 22%). However, in HF SR Ca(2+) content was increased (by 19%) when measured under voltage-clamp stimulation. Inhibiting the L-type Ca(2+) current (ICa-L) in control cells reproduced both the decrease in Ca(2+) transient amplitude and increase of SR Ca(2+) content observed in voltage-clamped HF cells. During ß-AR stimulation Ca(2+) transient amplitude was the same in control and HF cells. However, ICa-L remained less in HF than control cells whilst SR Ca(2+) content was highest in HF cells during ß-AR stimulation. The decrease in ICa-L that occurs in HF atrial myocytes appears to underpin the decreased Ca(2+) transient amplitude and increased SR Ca(2+) content observed in voltage-clamped cells.

Calcium signalling microdomains and the t-tubular system in atrial mycoytes: potential roles in cardiac disease and arrhythmias.

The atria contribute 25% to ventricular stroke volume and are the site of the commonest cardiac arrhythmia, atrial fibrillation (AF). The initiation of contraction in the atria is similar to that in the ventricle involving a systolic rise of intracellular Ca(2+) concentration ([Ca(2+)](i)). There are, however, substantial inter-species differences in the way systolic Ca(2+) is regulated in atrial cells. These differences are a consequence of a well-developed and functionally relevant transverse (t)-tubule network in the atria of large mammals, including humans, and its virtual absence in smaller laboratory species such as the rat. Where T-tubules are absent, the systolic Ca(2+) transient results from a 'fire-diffuse-fire' sequential recruitment of Ca(2+) release sites from the cell edge to the centre and hence marked spatiotemporal heterogeneity of systolic Ca(2+). Conversely, the well-developed T-tubule network in large mammals ensures a near synchronous rise of [Ca(2+)](i). In addition to synchronizing the systolic rise of [Ca(2+)](i), the presence of T-tubules in the atria of large mammals, by virtue of localization of the L-type Ca(2+) channels and Na(+)-Ca(2+) exchanger antiporters on the T-tubules, may serve to, respectively, accelerate changes in the amplitude of the systolic Ca(2+) transient during inotropic manoeuvres and lower diastolic [Ca(2+)](i). On the other hand, the presence of T-tubules and hence wider cellular distribution of the Na(+)-Ca(2+) exchanger may predispose the atria of large mammals to Ca(2+)-dependent delayed afterdepolarizations (DADs); this may be a determining factor in why the atria of large mammals spontaneously develop and maintain AF.

A functional role for transverse (t-) tubules in the atria.

Mammalian ventricular myocytes are characterised by the presence of an extensive transverse (t-) tubule network which is responsible for the synchronous rise of intracellular Ca(2+) concentration ([Ca(2+)]i) during systole. Disruption to the ventricular t-tubule network occurs in various cardiac pathologies and leads to heterogeneous changes of [Ca(2+)]i which are thought to contribute to the reduced contractility and increased susceptibility to arrhythmias of the diseased ventricle. Here we review evidence that, despite the long-held dogma of atrial cells having no or very few t-tubules, there is indeed an extensive and functionally significant t-tubule network present in atrial myocytes of large mammals including human. Moreover, the atrial t-tubule network is highly plastic in nature and undergoes far more extensive remodelling in heart disease than is the case in the ventricle with profound consequences for the resulting systolic Ca(2+) transient. In addition to considering the functional role of the t-tubule network in the healthy and diseased atria we also provide an overview of recent data concerning the putative factors controlling the formation of t-tubules and conclude by posing some important questions that currently remain to be addressed and whether or not targeting t-tubules offers potential novel therapeutic possibilities for heart disease.