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Smart hydrogels with wide visible color tunability
Get PDF© The Author(s) 2022. The version of record of this article, first published in [NPG Asia Materials], is available online at Publisher’s website: http://dx.doi.org/10.1038/s41427-022-00379-3The version of record of this article, first published in [NPG Asia Materials], is available online at Publisher’s website: http://dx.doi.org/10.1038/s41427-022-00379-3Pigmentary coloration can produce viewing angle-independent uniform colors via light absorption by chromophores. However, due to the limited diversity in the changes of the molecular configuration of chromophores to undergo color change, the existing materials cannot produce a wide range of visible colors with tunable color saturation and transmittance. Herein, we propose a novel strategy to create materials with a wide visible color range and highly tunable color saturation and transmittance. We fabricated a hydrogel with poly (acrylamide-co-dopamine acrylamide) networks swollen with Fe3+-containing glycerol/water in which the covalently crosslinked polyacrylamide backbone with pendant catechols can ensure that the hydrogel maintains a very stable shape. Hydrogels containing adjustable catechol-Fe3+ coordination bonds with flexible light-interacting configuration changes can display a wide range of visible colors based on the complementary color principle. The catechol-Fe3+ complexes can dynamically switch between noncoordinated and mono-, bis- and tris-coordinated states to harvest light energy from a specific wavelength across the whole visible spectrum. Therefore, these hydrogels can be yellow, green, blue, and red, covering the three primary colors. Moreover, color saturation and transmittance can be flexibly manipulated by simply adjusting the Fe3+ content in the hydrogel networks. The versatility of these smart hydrogels has been demonstrated through diverse applications, including optical filters for color regulation and colorimetric sensors for detecting UV light and chemical vapors. This proposed smart hydrogel provides a universal color-switchable platform for the development of multifunctional optical systems such as optical filters, sensors, and detectors
There You Are! Automated Detection of Indris’ Songs on Features Extracted from Passive Acoustic Recordings
Get PDFThe growing concern for the ongoing biodiversity loss drives researchers towards practical and large-scale automated systems to monitor wild animal populations. Primates, with most species threatened by extinction, face substantial risks. We focused on the vocal activity of the indri (Indri indri) recorded in Maromizaha Forest (Madagascar) from 2019 to 2021 via passive acoustics, a method increasingly used for monitoring activities in different environments. We first used indris’ songs, loud distinctive vocal sequences, to detect the species’ presence. We processed the raw data (66,443 10-min recordings) and extracted acoustic features based on the third-octave band system. We then analysed the features extracted from three datasets, divided according to sampling year, site, and recorder type, with a convolutional neural network that was able to generalise to recording sites and previously unsampled periods via data augmentation and transfer learning. For the three datasets, our network detected the song presence with high accuracy (>90%) and recall (>80%) values. Once provided the model with the time and day of recording, the high-performance values ensured that the classification process could accurately depict both daily and annual habits of indris‘ singing pattern, critical information to optimise field data collection. Overall, using this easy-to-implement species-specific detection workflow as a preprocessing method allows researchers to reduce the time dedicated to manual classification
Characterisation, antioxidant properties and cytoprotective investigation of Zanthoxylum zanthoxyloides root-bark in oxidative stressed promyelocytic leukaemia cells
Get PDFThere is great interest in traditional or folk medicines in order to help with the discovery and development of potentially new pharmaceutics which have clinical benefits to man. Many of these traditional medicines are derived from medicinal plants which have been shown to contain a multitude of chemicals that have potent natural antioxidant properties. The chemical composition (metabolites), characterisation, antioxidant properties and cytoprotective effects to oxidative stress of Zanthoxylum zanthoxyloides (ZZ) root-bark extract obtained from different seasonal conditions, namely: winter, spring, summer and autumn bought from an African store and during one annual collection, were investigated in this thesis. ZZ root-bark was prepared in in two solvents (ethanol and water) and three methods of extraction (Aq decoction and maceration as well as ethanolic maceration). The extracts were investigated using different methods such as moisture content analysis, percentage insoluble fraction, spectrocolorimetric measurements, ash content analysis, analysis of carbon, sulphur, nitrogen, hydrogen and oxygen analysis, gas chromatography-mass spectroscopy (GC-MS), ultra-violet-visible spectroscopy (UV-VIS), Fourier-transform infra-red spectroscopy (FT-IR), qualitative and quantitative phytochemical analyses. Its antioxidative effects was investigated by assessing the plant extract’s ability to scavenge or react with a range of different free radicals such as: 2,2-diphenyl-1-picrylhydrazyl radical (DPPH), hydroxyl radical (●OH), singlet oxygen radical (1O2), nitric oxide radical (NO●), 2,2-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS●+), metal ion, ferric reducing antioxidant power assay (FRAP) and reducing power assay. Lipopolysaccharide (LPS) and H2O2 were used to induce oxidative stress in human leukemic cells (U937 and HL60), and the ZZ extract was used to determine any potential cytoprotective effects to these oxidative insults.
The result presented in this thesis showed that the moisture content of ZZ root-bark extract for winter, summer, spring and autumn was between 6.75 – 8.07% and this is within the acceptable moisture content percentage (5 – 8%). A statistically significant difference of *P<0.5 (winter vs spring), ***P<0.001 (spring vs summer) and ****P<0.0001 (winter vs summer) was observed among these seasons. The percentage insoluble fraction of this extract, in both solvents, was about 90% for these seasonal conditions with no statistically significant difference among them. The percentage ash content was between 6.9 – 8.3% for these harvest seasons, with statistically significant difference of *P<0.5 (winter vs spring) and **P<0.01 (winter vs summer), and this is within the acceptable range (5 – 40%). ICP-MS analysis of this extract confirms the presence of calcium, manganese, gallium, strontium, barium, lanthanum and cerium for all extracts from different seasons. GC-MS analysis of ZZ confirms the presence of many metabolites such as alkyl amide, lipids, coumarin, alkaloids, phenolics and triterpenes from all seasons. UV-VIS spectroscopy analysis further confirmed the presence of flavonoids for all seasons. Physico-chemical quantification analyses also confirmed the presence of many of these constituents in the extract. Percentage CHNS-O was between 43 – 52 % for carbon, 0 – 0.21 % for nitrogen, 4 – 12 % for hydrogen and 35 – 41 % for oxygen. However, sulphur was not present in all seasons. The ZZ extract also showed a great ability to scavenge free radicals such as DPPH● (IC50 = 30 μg/ml), ●OH (IC50 = 0.08 mg/ml), H2O2 (IC50 = 0.08 mg/ml), NO● (IC50 = 0.20 mg/ml) 1O2 (IC50 = 0.16 mg/ml) ABTS●+ (IC50 = 0.23 mg/ml) and metal ion (IC50 = 0.11 mg/ml) by accepting hydrogen or electron but showed a weak FRAP and reducing power ability. Finally, the extract showed it had cytoprotective effect against lipopolysaccharide and hydrogen peroxide-induced oxidative stress leading to cell death in U937 and HL60 leukemic cells. A more detailed characterisation showed that the ZZ extract was able to statistically protect against oxidative stress-induced cell death caused by either apoptosis or necrosis. In conclusion, ZZ extract possesses many phytochemical compounds, many of which have antioxidants properties regardless of their harvest seasons. Findings from this thesis confirmed the potential health benefits of ZZ root-bark and could be valuable for pharmaceutical and nutraceutical industries in using it to reveal new sources of natural antioxidant for therapeutic drugs
Quotients of the Highwater algebra and its cover
Get PDF© 2023 The Author(s). Published by Elsevier Inc.Primitive axial algebras of Monster type are a class of non-associative algebras with a strong link to finite (especially simple) groups. The motivating example is the Griess algebra, with the Monster as its automorphism group. A crucial step towards the understanding of such algebras is the explicit description of the 2-generated symmetric objects. Recent work of Yabe, and Franchi and Mainardis shows that any such algebra is either explicitly known, or is a quotient of the infinite-dimensional Highwater algebra H, or its characteristic 5 cover Ĥ. In this paper, we complete the classification of symmetric axial algebras of Monster type by determining the quotients of H and Ĥ. We proceed in a unified way, by defining a cover of H in all characteristics. This cover has a previously unseen fusion law and provides an insight into why the Highwater algebra has a cover which is of Monster type only in characteristic 5.Published OA - VoR uploaded to CR 09/07/2025. AAM retained on record as both AAM & VoR have the same CC licence
Non‐invasive sampling reveals low mitochondrial genetic diversity for an island endemic species: The critically endangered Grenada Dove Leptotila wellsi
Get PDFAs an island endemic with a decreasing population, the critically endangered Grenada Dove Leptotila wellsi is threatened by accelerated loss of genetic diversity resulting from ongoing habitat fragmentation. Small, threatened populations are difficult to sample directly but advances in molecular methods mean that non‐invasive samples can be used. We performed the first assessment of genetic diversity of populations of Grenada Dove by (a) assessing mtDNA genetic diversity in the only two areas of occupancy on Grenada, (b) defining the number of haplotypes present at each site and (c) evaluating evidence of isolation between sites. We used non‐invasively collected samples from two locations: Mt Hartman (n = 18) and Perseverance (n = 12). DNA extraction and PCR were used to amplify 1751 bps of mtDNA from two mitochondrial markers: NADH dehydrogenase 2 (ND2) and Cytochrome b (Cyt b). Haplotype diversity (h) of 0.4, a nucleotide diversity (π) of 0.00023 and two unique haplotypes were identified within the ND2 sequences; a single haplotype was identified within the Cyt b sequences. Of the two haplotypes identified, the most common haplotype (haplotype A = 73.9%) was observed at both sites and the other (haplotype B = 26.1%) was unique to Perseverance. Our results show low mitochondrial genetic diversity and clear evidence for genetically isolated populations. The Grenada Dove needs urgent conservation action, including habitat protection and potentially augmentation of gene flow by translocation in order to increase genetic resilience and diversity with the ultimate aim of securing the long‐term survival of this critically endangered species
The Routledge Handbook of the New African Diasporic Literature
Get PDFThis is an Accepted Manuscript of a book chapter published by Routledge in [The Routledge Handbook of the New African Diasporic Literature] on [16/05/2024], available online: http://www.routledge.com/The-Routledge-Handbook-of-the-New-African-Diasporic-Literature/Losambe-Ojaide/p/book/9781032500461Engaging with concepts of exilic and transnational writing established by Edward Said, Stephen Clingman, and others, this chapter offers a comparative survey and analysis of a wide range of fiction and nonfiction representing South Africa’s internal and external diasporas, mostly published between 1994, year of its first-ever democratic election, and 2021. A brief overview of the country’s formative immigrations and the internal displacement and external exile created by segregation and apartheid is followed by four sections. The first discusses texts by or about post-liberation returnees, including ex-activists and white expatriates, as well as perspectives from South Africa’s Jewish community and its exiles. The second examines narratives by or about new continental immigrants from the rest of Africa, including refugees, and novels chronicling the intercontinental roots, oceanic routes, and immigrant experiences of South African Indians. The third and fourth sections provide contrasting case studies of revisionist émigrés: J.M. Coetzee, who scrutinizes the migrant’s ‘substitutive’ desire to start afresh; and Zoë Wicomb, whose ‘translocal’ refines the ‘combinatory’ transnational. The chapter argues that identities in the ‘new South Africa’ and its external diasporas are diasporic in diverse and complex ways that challenge and reconfigure the paradigms of ‘contrapuntal’ exile and celebratory cosmopolitanism/Afropolitanism
Tuberculosis-diabetes screening: how well are we doing? A mixed-methods study from North India
Get PDFSetting: Public health care facilities in Sonipat District, Haryana State, India.
Objectives: To assess 1) the proportion of tuberculosis (TB) patients screened for diabetes mellitus (DM) and vice versa, 2) factors associated with screening, and 3) the enablers, barriers and solutions related to screening.
Design: A mixed-methods study with quantitative (cohort study involving record reviews of patients registered between November 2016 and April 2017) and qualitative (interviews of patients, health care providers [HCPs] and key district-level staff) components.
Results: Screening for TB among DM patients was not implemented, despite documents indicating that it had been. Of 562 TB patients, only 137 (24%) were screened for DM. TB patients registered at tertiary and secondary health centres were more likely to be screened than primary health centres. Low patient awareness, poor knowledge of guidelines among HCPs, lack of staff and inadequate training were barriers to screening. Enablers were the positive attitude of HCPs and programme staff. The key solutions suggested were to improve awareness of HCPs and patients regarding the need for screening, training of HCPs and wider availability of DM testing facilities.
Conclusion: The implementation of bidirectional screening was poor. Adequate staffing, regular training, continuous laboratory supplies for DM diagnosis and widespread publicity should be ensured
Skeletal muscle differentiation drives a dramatic downregulation of RNA polymerase III activity and differential expression of Polr3g isoforms
Get PDFGene regulatory networks underpinning skeletal muscle determination and differentiation have been extensively investigated, providing molecular insights into how cell lineages are established during development. These studies have exclusively focused on the transcriptome downstream of RNA polymerase II (Pol II). RNA polymerase III (Pol III) drives the production of tRNAs and other small RNAs essential for the flow of genetic information from gene to protein and we have found that a specific isoform of a subunit unique to Pol III is expressed early in the myogenic lineage. This points to the possibility that additional regulatory networks exist to control the production of Pol III transcripts during skeletal muscle differentiation. We describe the differential expression of Polr3g and its alternate isoform Polr3gL during embryonic development and using a custom tRNA microarray, we demonstrate their distinct activity on the synthesis of tRNA isoacceptors. We show that Pol III dependent transcripts are dramatically down-regulated during the differentiation of skeletal muscle, as are mRNAs coding for Pol III associated proteins Brf1 and Brf2, while Polr3gL is up-regulated alongside contractile protein genes. Forcing Polr3g expression in this context results in a partial reversal of myogenic differentiation
Crafting a Sense of Self: Exploring amateur arts-based practice within a university business school context
Get PDFThis research uses arts-based practice in a pivotal role both as a research context and methodological means, within a university business school setting. A personal creative rupture, challenging my sense of professional self, prompts the central research aims to: (1) analyse how amateur arts-based practice shapes university business school lecturers’ sense of self; (2) gain new understanding of creative learning processes applied to a business school context, and (3) explore the use of an artefact-based data collection method to elicit rich participant narratives around selfhood. Participant voices of a micro sample of business school educators are at the heart of the research. Narrative accounts of their lived creative experiences illuminate and synthesise perceptions on sense of self and place, both creatively and professionally, and how it can be subject to various practices. Their symbolic artefacts steer conversational style interviews, supporting a social constructivist orientation. Bourdieu’s concept of habitus acts as a central mode of analysis. Case analyses collate and re-frame participants’ stories about shaping of selfhoods. The instrumental nature of artefacts is explored in prompting sensitive, private and potentially inaccessible insights into crafter and professional selfhoods, challenging the role of more conventional research methods.
Perceptions of amateur creative practice, from a university business school perspective, reveal how the two seemingly disparate worlds intersect. For some business school lecturers, their creative practice plays a large part in their lives. For others it is more functional. Findings suggest the varying degree of intersectionality is influenced by the inner structures of habitus alongside external structures within fields of practice, drawing on the duality of Bourdieu’s sociology. Through heuristic processes the transformational nature of habitus is investigated. Findings identify the enabling and constraining nature of embodied dispositions. This contributes fresh insights into creative and professional selfhoods, including value systems, attitudes to risk and coping strategies for practice in navigating change and sense of agency. What has been identified are potential alternative routes to gaining insight into creative processes and practice and transformation of selfhoods, within the already fast-growing domain of arts-based methods Findings show unifying and varying benefits and impacts of creative practice on both personal and professional selfhoods as university business school lecturer. Amateur creative practice varies including motives, cognitive and affective benefits, degrees of engagement and attitudes to risk. The research offers a deeper layer of reflexivity on educational philosophy, perceived tensions and the value of creative intelligence within a university business school context. It also offers valuable perspective on the responsibility as educator in creating safe temporal and mental space to nurture business school learner creativity
Software Exploitation and Software Protection Measures Enhancing Software Protection via Inter-Process Control Flow Integrity
Get PDFComputer technologies hinge on the effective functionality of the software component. Unfortunately, software code may have flaws that cause them to be vulnerable and exploitable by attackers. Software exploitation could involve a hijack of the application and deviation of the flow of its execution. Whenever this occurs, the integrity of the software and the underlying system could be compromised. For this reason, there is a need to continually develop resilient software protection tools and techniques. This report details an in-depth study of software exploitation and software protection measures. Efforts in the research were geared towards finding new protection tools for vulnerable software. The main focus of the study is on the problem of Control Flow Hijacks (CFH) against vulnerable software, particularly for software that was built and executed on the RISC-V architecture. Threat models that were addressed are buffer overflow, stack overflow, return-to-libc, and Return Oriented Programming (ROP). Whilst the primary focus for developing the new protection was on RISC-V-based binaries, programs that were built on the more widespread x86 architecture were also explored comparatively in the course of this study.
The concept of Control Flow Integrity (CFI) was explored in the study and a proof-of-concept for mitigating ROP attacks that result in Denial of Service is presented. The concept of CFI involves the enforcement of the intended flow of execution of a vulnerable program. The novel protection is based on the CFI concept combined with Inter-process signalling (named Inter-Process Control Flow Integrity (IP-CFI)). This technique is orthogonal to well-practised software maintenance such as patching/updates and is complementary to it providing integrity regardless of exploitation path/vector. In evaluating the tool, it was applied to vulnerable programs and found to promptly identify deviations in vulnerable programs when ROP attacks lead to DoS with an average runtime overhead of 0.95%. The system on which the software is embedded is also protected as a result of the watchdog in the IP-CFI where this kind of attack would have progressed unnoticed. Unlike previous CFI models, IP-CFI extends protection outside the vulnerable program by setting up a mutual collaboration between the protected program and a newly written monitoring program. Products derived in this study are software tools in the form of various Linux scripts that can be used to automate several functionalities, two RISC-V ROP gadget finders (RETGadgets & JALRGadget), and the software protection tool IP-CFI. In this report, software is also referred to as binary, executable, application, program or process
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