Graphene kirigami as a platform for stretchable and tunable quantum dot arrays

The quantum transport properties of a graphene kirigami similar to those studied in recent experiments are calculated in the regime of elastic, reversible deformations. Our results show that, at low electronic densities, the conductance profile of such structures replicates that of a system of coupled quantum dots, characterized by a sequence of minibands and stop-gaps. The conductance and I-V curves have different characteristics in the distinct stages of elastic deformation that characterize the elongation of these structures. Notably, the effective coupling between localized states is strongly reduced in the small elongation stage, whereas in the large elongation regime the development of strong, localized pseudomagnetic field barriers can reinforce the coupling and reestablish resonant tunneling across the kirigami. This provides an interesting example of interplay between geometry and pseudomagnetic field-induced confinement. The alternating miniband and stop-gaps in the transmission lead to I-V characteristics with negative differential conductance in well defined energy/doping ranges. These effects should be stable in a realistic scenario that includes edge roughness and Coulomb interactions, as these are expected to further promote localization of states at low energies in narrow segments of graphene nanostructures.Comment: 10 pages, 10 figure

Establishing gold standard approaches to rapid tranquillisation: a review and discussion of the evidence on the safety and efficacy of medications currently used

Background: Rapid tranquillisation is used when control of agitation, aggression or excitement is required. Throughout the UK there is no consensus over the choice of drugs to be used as first line treatment. The NICE guideline on the management of violent behaviour involving psychiatric inpatients conducted a systematic examination of the literature relating to the effectiveness and safety of rapid tranquillisation (NICE, 2005). This paper presents the key findings from that review and key guideline recommendations generated, and discusses the implications for practice of more recent research and information. Aims: To examine the evidence on the efficacy and safety of medications used for rapid tranquillisation in inpatient psychiatric settings. Method: Systematic review of current guidelines and phase III randomised, controlled trials of medication used for rapid tranquillisation. Formal consensus methods were used to generate clinically relevant recommendations to support safe and effective prescribing of rapid tranquillisation in the development of a NICE guideline. Findings: There is a lack of high quality clinical trial evidence in the UK and therefore a ‘gold standard’ medication regime for rapid tranquillisation has not been established. Rapid tranquillisation and clinical practice: The NICE guideline produced 35 recommendations on rapid tranquillisation practice for the UK, with the primary aim of calming the service user to enable the use of psychosocial techniques. Conclusions and implications for clinical practice: Further UK specific research is urgently needed that provides the clinician with a hierarchy of options for the clinical practice of rapid tranquillisation

Peralkaline and alkaline magmatism of the Ossa-Morena Zone (SW Iberia): age, source and implications for the Paleozoic evolution of Gondwanan lithosphere

The Ossa-Morena zone in SW Iberia represents a section of the northern margin of West Gondwana that formed part of a Cordilleran-type orogenic system during the Neoproterozoic (Cadomian orogeny). The crustal section in this zone preserves the record of rifting that led to the opening of the Rheic Ocean in the early Paleozoic and the collision of Gondwana and Laurussia in the late Paleozoic (Variscan orogeny). We present U-Pb zircon data from three alkaline to peralkaline syenites that intruded Neoproterozoic and Cambrian strata and give crystallization ages ranging between ca. 490 Ma and 470 Ma. Lu/Hf isotopic data from these zircons give positive initial eHf values (0 ≤ eHf(t) ≤ +11.5) that approach the model values for the depleted mantle at the time of crystallization. This suggests that a significant proportion of the magma was derived from the mantle, with limited mixing/assimilation with crustal-derived melts. Alkaline/peralkaline magmatic suites of similar age and chemical composition intruded other sections of the northern margin of West Gondwana and along the boundaries of the continental blocks that today make up Iberia. These blocks are further characterized by the presence of high-pressure metamorphic belts that formed during accretion and subsequent collision of peri-Gondwanan domains against Laurussia during the Devonian and Carboniferous (Variscan orogeny). Our U-Pb and Lu-Hf data set indicates that during the Cambrian–Ordovician transition, lithosphere extension reached a stage of narrow intracontinental rifting, where deeply sourced magmas, probably coming from the lower crust and/or the upper mantle, intruded continental upper crust across various sections of previously stretched crust. We propose that necking of the Gondwana lithosphere into several continental microblocks with fertile mantle beneath them compartmentalized extension (multiblock model), which favored the onset of early Paleozoic peralkaline and alkaline magmas. The boundaries of microblocks represent zones of inherited crustal weakness that were later reactivated during the late Paleozoic as major accretionary faults related to the amalgamation of Pangea during the Variscan orogeny. Our dynamic model provides an explanation for the unusual spatial relationship between peralkaline and alkaline igneous provinces (usually shallow in the crust) and the occurrence of high-pressure rocks. Our observations suggest that Cordilleran-type orogens subjected to extension after long-lived subduction can develop wide continental platforms that feature multiple continental blocks. In addition, the formation of sequenced high-pressure belts in collisional orogens can be explained as the ultimate consequence of multiple necking events within continental lithosphere during previous collapse of a Cordilleran-type orogen

Semiflexible polymer condensates in poor solvents: toroid versus spherical geometries

Semiflexible polymers, such as DNA, in the presence of a condensing agent often form toroids. This is due to a balance between bending and surface area free energy penalties. Here we show why in experiments all the toroids have been found to have similar physical size. We also introduce a novel morphology, that of the hollow sphere, which is favored for long polymer chains. This offers the possibility of encapsulating material inside a “vesicle” made of semiflexible polymers. We also consider the case of many such polymer chains placed in a poor solvent. We show a transition between two morphologies occur on increasing concentration of polymer chains, from a thickened toroid to a spherical globule

Moving from traditional government to new adaptive governance: the changing face of food security responses in South Africa

The food system faces increasing pressure from dynamic and interactive, environmental, political and socio-economic stressors. Tackling the complexity that arises from such interactions requires a new form of 'adaptive governance'. This paper provides a review of various conceptions of governance from a monocentric or politicotechnical understanding of governance through to adaptive governance that is based in complex adaptive systems theory. The review is grounded by a critique of the existing institutional structures responsible for food security in South Africa. The current Integrated Food Security Strategy and tasked governmental departments are not sufficiently flexible or coordinated to deal with an issue as multi-scalar and multidisciplinary as food security. However, actions taken in the non-governmental sector signal the emergence of a new type of governance. Apart from an increasing recognition of food security as an issue of concern in the country, there is also evidence of a changing governance structure including collaboration between diverse stakeholders. We review these governance trends with an understanding of the food system as a complex adaptive socio-ecological system where actors in the food system self-organize into more flexible networks that can better adapt to uncertain pressure

Beetroot as a source of natural dyes for ham

Beetroot (Beta vulgaris L.) was subjected to extraction procedures in order to obtain the respective extracts containing the natural dyes and subjected to cytotoxicity assays in AGS cell line. Encapsulation of the extracts in nanosystems based on soybean lecithin and maltodextrin was performed. Lyophilized extracts before and after encapsulation in maltodextrin were applied in the formulation of leg ham and used in pilot scale of production. The colour of ham samples from the different assays was evaluated visually and by colorimetry.Dias, S.; Pereira, D.M.; Castanheira, E.M.S.; Fortes, A.G.; Pereira, R.; Gonçalves, a.M.S.T. Beetroot as a Source of Natural Dyes for Ham. Proceedings 2019, 41, 82. https://doi.org/10.3390/ecsoc-23-0662

Stress response of European seabass (Dicentrarchus labrax) fed plant-based diets supplemented with swine blood hydrolysates

To improve fish welfare, it is essential that aquafeeds are designed to help fish cope with the stressful conditions of fish farms. One effective strategy to achieve this goal is to supplement the diet with bioactive hydrolysates. Here, diet supplementation to modulate oxidative stress after air exposure was investigated in European seabass, using swine blood hydrolysates (BH), obtained either by autohydrolysis (AH) or enzymatically. The enzymatically produced BH were further submitted to a micro- (RMF) and nanofiltration (RNF). Four isolipidic, isoproteic and isoenergetic diets were developed: a plant-based diet with low (12.5%) fishmeal levels (control, CTRL) and three diets where 3% of each BH (RMF, RNF and AH) was added to the CTRL. Diets were assigned to triplicate groups of 71 European seabass juveniles (initial weight 12.3 ± 1.4 g). After 12 weeks, 9 fish per treatment were either immediately sampled or air-exposed for 1 min and let to recover in a new system for 6 h prior to sampling. Stress response increased cortisol levels, followed by an increment in plasma lactate. The challenge increased liver lipid peroxidation (LPO) due to reactive oxygen species (ROS) accumulation. Carbonyls decreased post-stress, maybe due to a possible interaction with the LPO radicals, reducing protein oxidation. None of the BH improved plasma stress response. By reducing catalase levels without increasing LPO, the RNF treatment appears to adjust European seabass' antioxidant defences, indicating its potential to supply exogenous antioxidants to combat oxidative stress induced by ROS. However, this impact was not sufficient to lower LPO levels compared to a control plant-based diet. The tested diets seemed to affect the fish oxidative stress response in the liver, possibly due to the presence of bioactive peptides, which aided in the non-enzymatic modulation of stress response, as observed by the total antioxidant capacity values in the liver.info:eu-repo/semantics/publishedVersio

Laser-fabricated porous alumina membranes (LF-PAM) for the preparation of metal nanodot arrays

We report on an efficient photonic-based method to prepare nanodot array of functional materials, independently of the nature of the substrate.Comment: Small (2008) Accepte

Evaluation of a model photo-caged dehydropeptide as a stimuli-responsive supramolecular hydrogel

Short peptides capped on the N-terminus with aromatic groups are often able to form supramolecular hydrogels, via self-assembly, in aqueous media. The rheological properties of these readily tunable hydrogels resemble those of the extracellular matrix (ECM) and therefore have potential for various biological applications, such as tissue engineering, biosensors, 3D bioprinting, drug delivery systems and wound dressings. We herein report a new photo-responsive supramolecular hydrogel based on a “caged” dehydropeptide (CNB-Phe-ΔPhe-OH 2), containing a photo-cleavable carboxy-2-nitrobenzyl (CNB) group. We have characterized this hydrogel using a range of techniques. Irradiation with UV light cleaves the pendant aromatic capping group, to liberate the corresponding uncaged model dehydropeptide (H-Phe-ΔPhe-OH 3), a process which was investigated by 1H NMR and HPLC studies. Crucially, this cleavage of the capping group is accompanied by dissolution of the hydrogel (studied visually and by fluorescence spectroscopy), as the delicate balance of intramolecular interactions within the hydrogel structure is disrupted. Hydrogels which can be disassembled non-invasively with temporal and spatial control have great potential for specialized on-demand drug release systems, wound dressing materials and various topical treatments. Both 2 and 3 were found to be non-cytotoxic to the human keratinocyte cell line, HaCaT. The UV-responsive hydrogel system reported here is complementary to previously reported related UV-responsive systems, which are generally composed of peptides formed from canonical amino acids, which are susceptible to enzymatic proteolysis in vivo. This system is based on a dehydrodipeptide structure which is known to confer proteolytic resistance. We have investigated the ability of the photo-activated system to accelerate the release of the antibiotic, ciprofloxacin, as well as some other small model drug compounds. We have also conducted some initial studies towards skin-related applications. Moreover, this model system could potentially be adapted for on-demand “self-delivery”, through the uncaging of known biologically active dehydrodipeptides.This work was supported by the Portuguese Foundation for Science and Technology (FCT) in the framework of the Strategic Funding of CQUM (UID/QUI/00686/2019) and of IPC (UID/CTM/50025/2019). L.H. acknowledges funding from the FCT Investigator Programme through grant IF/00606/2014. FCT, FEDER, PORTUGAL2020 and COMPETE2020 are also acknowledged for funding under research project PTDC/QUI-QOR/29015/2017 (POCI-01-0145-FEDER-029015)