Multicompartment thermoresponsive gels: Does the length of the hydrophobic side group matter?

Multicompartment thermoresponsive gels are novel materials with fascinating self-assembly and interesting applications. The aim of this study was to investigate for the first time the effect of the length of the alkyl side group of a hydrophobic monomer on the thermoresponsive and self-assembly behaviour of terpolymers. Specifically twelve well-defined terpolymers based on the hydrophilic monomers 2-(dimethylamino)ethyl methacrylate (DMAEMA) and poly(ethylene glycol) methyl ether methacrylate (PEGMA), and on the hydrophobic monomer ethyl-, n-butyl or n-hexyl methacrylate (EtMA, BuMA or HMA) of varying architectures (ABC, ACB, BAC and statistical) were synthesised using Group Transfer Polymerisation. The A, B and C blocks were based on PEGMA, the alkyl containing methacrylate monomer, and DMAEMA, respectively. The molecular weights (MWs) and compositions of the polymers were kept the same. The polymers and their precursors were characterised in terms of their MWs, MW distributions and compositions. Aqueous solutions of the polymers were studied by turbidimetry, hydrogen ion titration, light scattering and rheology to determine their cloud points, pKas, hydrodynamic diameters and thermoresponsive behaviour and investigate the effect of the architecture and the hydrophobic alkyl side group of the terpolymers. It was found that the pKas and the Tgs were mostly affected by the hydrophobicity of the side groups and not by the architecture, while the cloud points and the sol-gel transition of the polymers were affected by both the length of the alkyl side group and the polymer architecture. Interestingly the sharpest sol-gel transitions and stable multicompartment hydrogels were observed for the ABC triblock copolymers with the short alkyl-side groups even though the sol-gel transition occurred at higher temperatures

The generalized data management and collection protocol for Conductivity-Temperature-Depth Satellite Relay Data Loggers

Abstract The software routines for data sampling and processing that are implemented on-board telemetry devices (tags) called Conductivity-Temperature-Depth Satellite Relay Data Loggers (CTD-SRDLs) enable the simultaneous collection of biological and in-situ environmental data by animal-platforms over periods of weeks to months, despite severe energy and bandwidth limitations imposed by their relatively small size. This extended operational lifetime is made possible by the use of software protocols on-board the tags that manage sensors, data collection, storage, compression and transmission to ensure that the most useful data are sent at appropriate resolution while minimizing redundancy. While tag software is tailored to the particular species under study and the questions being addressed with a given field deployment, the philosophy behind Sea Mammal Research Unit Instrumentation Group (SMRU-IG) software protocols is to adopt a general set of principles to achieve the best results within the energy and bandwidth constraints. Here, we discuss these and review the general protocol that is used to simultaneously collect information on geographical movements, diving behaviour and in-situ oceanographic information from marine mammals

ABC block copolymer micelles driving the thermogelation:Scattering, imaging and spectroscopy

Thermoresponsive polymers have attracted much scientific attention due to their capacity for temperature-driven hydrogel formation. For biomedical applications, such as drug delivery, this transition should be tuned below body temperature to facilitate controlled and targeted drug release. We have recently developed a thermoresponsive polymer that forms gel at low concentrations (2 w/w%) in aqueous media and offers a cost-effective alternative to thermoresponsive systems currently being applied in clinics. This polymer is an ABC triblock terpolymer, where A, B, and C correspond to oligo(ethylene glycol) methyl ether methacrylate with average Mn 300 g mol−1 (OEGMA300), n-butyl methacrylate (BuMA), and di(ethylene glycol) methyl ether methacrylate (DEGMA). To investigate the self-assembly and the gelation mechanism in diluted solutions, we used small-angle neutron scattering (SANS) on 1 w/w% (below the gelation concentration) and 5 w/w% solutions (above the gelation concentration). As a comparison, we also investigated the solutions of the most studied thermoresponsive polymer, namely, Pluronic F127, an ABA triblock bipolymer made of ethylene glycol (A) and propylene glycol (B) blocks. SANS revealed that the in-house synthesised polymer forms elliptical cylinders, whose length increases significantly with temperature. In contrast, Pluronic F127 solutions form core-shell spherical micelles, which slightly elongate with temperature. Transmission electron microscopy images support the SANS findings, with tubular/worm structures being present. Variable-temperature circular dichroism (CD) and proton nuclear magnetic resonance (1H NMR) spectroscopy experiments reveal insights on the tacticity, structural changes, and molecular origin of the self-assembly

Accurate epigenetic aging in bottlenose dolphins (Tursiops truncatus), an essential step in the conservation of at-risk dolphins

Funding: This research was funded by SERDP grant RC20-C2-1097 awarded to Peter Tyack and Prescott Award NA20NMF4390132 awarded to Ashley Barratclough.Epigenetics, specifically DNA methylation, allows for the estimation of animal age from blood or remotely sampled skin. This multi-tissue epigenetic age estimation clock uses 110 longitudinal samples from 34 Navy bottlenose dolphins (Tursiops truncatus), identifying 195 cytosine-phosphate-guanine sites associated with chronological aging via cross-validation with one individual left out in each fold (R2 = 0.95). With a median absolute error of 2.5 years, this clock improves age estimation capacity in wild dolphins, helping conservation efforts and enabling a better understanding of population demographicsPublisher PDFPeer reviewe

Summer at the beach: spatio-temporal patterns of white shark occurrence along the inshore areas of False Bay, South Africa

Background Understanding white shark (Carcharodon carcharias) habitat use in coastal areas adjacent to large cities, is an important step when formulating potential solutions to the conservation conflict that exists between humans and large predatory sharks. In this study, we present the findings of a 2.5-year study of white shark occurrence and movement patterns adjacent to the City of Cape Town in False Bay, South Africa, with a focus on spring and summer months. Fifty-one white sharks were monitored annually at three offshore and twelve inshore sites by VR2 acoustic receivers, over 975 days from 1 May 2005 to 31 December 2007. Results Occurrence patterns at inshore sites during spring and summer were analysed using a generalized additive mixed model (GAMM) with a spatial term (longitude, latitude), time of day and year included as explanatory variables for site use. We found that sharks occurred more frequently at inshore sites along the northern and northwestern shores, compared to the rest of the bay, and they transitioned most frequently between four adjacent beach sites that encompass the most popular recreational water use areas in Cape Town. There was significant diel variation, with higher shark occurrence around midday, and a peak in shark occurrence in 2005, when human-shark interactions also peaked. However, we found no effect of shark size on occurrence patterns at inshore sites. Conclusions White sharks showed the highest levels of occurrence at specific inshore sites between Muizenberg and Strandfontein beach, and thus inclusion of these sites within False Bay’s marine protected area (MPA) network or recognition as Ecological or Biological Significant Areas (EBSAs) should be a future consideration. These insights into white shark habitat use at inshore sites in False Bay are important for successfully applying the principles of marine spatial planning (MSP) and for making science-based policy decisions. Furthermore, this information can be used to reduce potential shark-human conflict by incorporating it into future shark safety education campaigns

Sex and size influence the spatiotemporal distribution of white sharks, with implications for interactions with fisheries and spatial management in the southwest Indian Ocean

The study was made possible through generous funding by Fischer Productions for fieldwork and equipment costs. TP was supported by a postdoctoral fellowship funded by the Nelson Mandela University Research Career Development Office (2016-2018) and funding from the South African Research Chairs Initiative awarded to Prof AT Lombard by the National Research Foundation, and by a Royal Society Newton International Fellowship (2018-2020, NF170682).Human activities in the oceans increase the extinction risk of marine megafauna. Interventions require an understanding of movement patterns and the spatiotemporal overlap with threats. We analysed the movement patterns of 33 white sharks (Carcharodon carcharias) satellite-tagged in South Africa between 2012 and 2014 to investigate the influence of size, sex and season on movement patterns and the spatial and temporal overlap with longline and gillnet fisheries and marine protected areas (MPAs). We used a hidden Markov model to identify ‘resident’ and ‘transient’ movement states and investigate the effect of covariates on the transition probabilities between states. A model with sex, total length and season had the most support. Tagged sharks were more likely to be in a resident state near the coast and a transient state away from the coast, while the probability of finding a shark in the transient state increased with size. White sharks moved across vast areas of the southwest Indian Ocean, emphasising the need for a regional management plan. White sharks overlapped with longline and gillnet fisheries within 25% of South Africa’s Exclusive Economic Zone and spent 15% of their time exposed to these fisheries during the study period. The demersal shark longline fishery had the highest relative spatial and temporal overlap, followed by the pelagic longline fishery and the KwaZulu-Natal (KZN) shark nets and drumlines. However, the KZN shark nets and drumlines reported the highest white shark catches, emphasising the need to combine shark movement and fishing effort with reliable catch records to assess risks to shark populations accurately. White shark exposure to shark nets and drumlines, by movement state, sex and maturity status, corresponded with the catch composition of the fishery, providing support for a meaningful exposure risk estimate. White sharks spent significantly more time in MPAs than expected by chance, likely due to increased prey abundance or less disturbance, suggesting that MPAs can benefit large, mobile marine megafauna. Conservation of white sharks in Southern Africa can be improved by implementing non-lethal solutions to beach safety, increasing the observer coverage in fisheries, and continued monitoring of movement patterns and existing and emerging threats.Publisher PDFPeer reviewe

Thermoresponsive triblock copolymers based on methacrylate monomers: Effect of molecular weight and composition

A series of amphiphilic thermoresponsive ABC triblock copolymers was synthesised by Group Transfer Polymerisation (GTP). In total nine polymers were prepared based on the non-ionic hydrophobic n-butyl methacrylate (BuMA), the ionisable hydrophilic and thermoresponsive 2-(dimethylamino)ethyl methacrylate (DMAEMA) and the non-ionic hydrophilic methoxy poly(ethylene glycol) methacrylate (PEGMA). The architecture of the copolymers was kept constant with the hydrophobic block in the middle and the two hydrophilic blocks at the two ends, while the composition and the molecular weight of the polymers were varied. Specifically the molecular weight of the polymers was varied while the composition and the architecture were kept constant. The precursors to the polymers and the polymers were characterised in terms of their molecular weight and composition using gel permeation chromatography and proton nuclear magnetic resonance spectroscopy, respectively. Aqueous solutions of the polymers were studied by turbidimetry, hydrogen ion titration and light scattering to determine their cloud points, pK as, and hydrodynamic diameters and investigate the effect of the composition and the molecular weight of the copolymers. Finally, the thermoresponsive behaviour of the copolymers was also studied and it was found that the cloud point and gel point of the polymers were strongly affected by both the composition and molecular weight of the triblock copolymers

Analytical methods and techniques for determining the quality of water reverse osmosis pilot plant

141 σ.Το νερό αποτελεί ένα από τα πιο πολύτιμα στοιχεία, που είναι απαραίτητο για τη διατήρηση της ζωής στον πλανήτη μας. Ιδιαίτερη προσοχή πρέπει να δίνεται τόσο στα επιφανειακά όσο και στα υπόγεια νερά που προορίζονται για ανθρώπινη κατανάλωση, ώστε το νερό να είναι αβλαβές και πόσιμο. Προς αυτή την κατεύθυνση έχουν οριστεί δείκτες ποιότητας του νερού, που καθορίζουν εάν το νερό είναι κατάλληλο ή όχι. Επιπλέον έχουν βρεθεί μέθοδοι επεξεργασίας για να βελτιώνουν την ποιότητα του νερού, ακόμα και να βοηθούν στην παραγωγή επεξεργασμένου νερού ανώτερης ποιότητας. Στην παρούσα εργασία θα γίνει παρουσίαση της μεθόδου της αντίστροφης ώσμωσης, που χρησιμοποιείται ολοένα και περισσότερο στις μέρες μας ως κύρια μέθοδος επεξεργασίας του νερού, αλλά ακόμα και συνδυαστικά με άλλες μεθόδους. Συγκεκριμένα μελετώνται οι αναλυτικές μέθοδοι και τεχνικές προσδιορισμού της ποιότητας νερού σε μια πιλοτική μονάδα αντίστροφης ώσμωσης. Γι’ αυτό το σκοπό γίνεται πλήρη αναφορά των οργάνων και υλικών που χρησιμοποιήθηκαν σε αυτές τις μεθόδους, καθώς γίνεται και περιγραφή των τεχνικών προσδιορισμού. Στο τέλος της εργασίας παρουσιάζονται τα αποτελέσματα από τη πιλοτική μονάδα αντίστροφης ώσμωσης με την απεικόνιση τους σε διαγράμματα και πίνακες. Η εργασία αυτή αποδεικνύει την αποτελεσματικότητα της μεθόδου της αντίστροφης ώσμωσης, ειδικότερα όταν στη μονάδα συνδυάζονται και άλλες μέθοδοι που βελτιώνουν την ποιότητα του νερού.Water is one of the most valuable elements, necessary for sustaining life on our planet. Particular attention should be given to both surface and underground waters intended for human consumption, so water is harmless and drinking. Towards this end have designated quality indicators water, determine if the water is suitable or not. Furthermore, they have find treatments to improve water quality even help to produce treated water more quality. This work will be presented the method of reverse osmosis, used increasingly in Nowadays as a primary method of water treatment, but even combination with other methods. Specifically studied the analytical methods and techniques for determining water quality in a pilot reverse osmosis unit. For this purpose becomes full report instrumentation and materials used in these methods, well done and a description of identification techniques. At the end of work presents the results from the pilot plant reverse osmosis to display them in charts and tables. This work demonstrates the effectiveness of the method of reverse osmosis, especially when combined unit and other methods that improve water quality.Θεώνη Α. Αναγνωστοπούλο