• The role of rock joint frictional strength in the containment of fracture propagation

      Eshiet, KII; Sheng, Y (Springer Nature, 2016-12-31)
      © 2016, The Author(s). The fracturing phenomenon within the reservoir environment is a complex process that is controlled by several factors and may occur either naturally or by artificial drivers. Even when deliberately induced, the fracturing behaviour is greatly influenced by the subsurface architecture and existing features. The presence of discontinuities such as joints, artificial and naturally occurring faults and interfaces between rock layers and microfractures plays an important role in the fracturing process and has been known to significantly alter the course of fracture growth. In this paper, an important property (joint friction) that governs the shear behaviour of discontinuities is considered. The applied numerical procedure entails the implementation of the discrete element method to enable a more dynamic monitoring of the fracturing process, where the joint frictional property is considered in isolation. Whereas fracture propagation is constrained by joints of low frictional resistance, in non-frictional joints, the unrestricted sliding of the joint plane increases the tendency for reinitiation and proliferation of fractures at other locations. The ability of a frictional joint to suppress fracture growth decreases as the frictional resistance increases; however, this phenomenon exacerbates the influence of other factors including in situ stresses and overburden conditions. The effect of the joint frictional property is not limited to the strength of rock formations; it also impacts on fracturing processes, which could be particularly evident in jointed rock masses or formations with prominent faults and/or discontinuities.
    • The role of sexual orientation, age, living arrangements and self-rated health in planning for end-of-life care for lesbian, gay and bisexual (LGB) older people in the UK

      Makita, M; Bahena, A; Almack, K (SAGE, 2020-06-17)
      © The Author(s) 2020. This article reports on findings from the quantitative phase of a two-year research project designed to explore end-of-life care experiences and needs of lesbian, gay, bisexual and transgender people. We draw on a subset of the sample (N = 180/237) to analyse the relationship between advance care planning, sexual orientation, living arrangements and self-rated health. The results contribute to a growing body of evidence on how sexual minorities approach and make decisions on advance care planning. A greater understanding of such patterns could help inform the way healthcare professionals engage in conversations about end-of-life care planning with older LGB people.
    • The role of WNT signalling in chronic kidney disease (CKD)

      Malik, SA; Modarage, K; Goggolidou, P; Department of Biomedical Science and Physiology, Faculty of Science and Engineering, University of Wolverhampton, Wulfruna Street, Wolverhampton WV1 1LY, UK. (MDPI, 2020-04-30)
      © 2020 by the authors. Licensee MDPI, Basel, Switzerland. Chronic kidney disease (CKD) encompasses a group of diverse diseases that are associated with accumulating kidney damage and a decline in glomerular filtration rate (GFR). These conditions can be of an acquired or genetic nature and, in many cases, interactions between genetics and the environment also play a role in disease manifestation and severity. In this review, we focus on genetically inherited chronic kidney diseases and dissect the links between canonical and non-canonical Wnt signalling, and this umbrella of conditions that result in kidney damage. Most of the current evidence on the role of Wnt signalling in CKD is gathered from studies in polycystic kidney disease (PKD) and nephronophthisis (NPHP) and reveals the involvement of beta-catenin. Nevertheless, recent findings have also linked planar cell polarity (PCP) signalling to CKD, with further studies being required to fully understand the links and molecular mechanisms.
    • The roles of vicariance and isolation by distance in shaping biotic diversification across an ancient archipelago: evidence from a Seychelles caecilian amphibian

      Maddock, Simon T; Nussbaum, Ronald A; Day, Julia J; Latta, Leigh; Miller, Mark; Fisk, Debra L; Wilkinson, Mark; Rocha, Sara; Gower, David J; Pfrender, Michael E (Springer Science and Business Media LLC, 2020-08-26)
      Background Island systems offer excellent opportunities for studying the evolutionary histories of species by virtue of their restricted size and easily identifiable barriers to gene flow. However, most studies investigating evolutionary patterns and processes shaping biotic diversification have focused on more recent (emergent) rather than ancient oceanic archipelagos. Here, we focus on the granitic islands of the Seychelles, which are unusual among island systems because they have been isolated for a long time and are home to a monophyletic radiation of caecilian amphibians that has been separated from its extant sister lineage for ca. 65–62 Ma. We selected the most widespread Seychelles caecilian species, Hypogeophis rostratus, to investigate intraspecific morphological and genetic (mitochondrial and nuclear) variation across the archipelago (782 samples from nine islands) to identify patterns and test processes that shaped their evolutionary history within the Seychelles. Results Overall a signal of strong geographic structuring with distinct northern- and southern-island clusters were identified across all datasets. We suggest that these distinct groups have been isolated for ca. 1.26 Ma years without subsequent migration between them. Populations from the somewhat geographically isolated island of Frégate showed contrasting relationships to other islands based on genetic and morphological data, clustering alternatively with northern-island (genetic) and southern-island (morphological) populations. Conclusions Although variation in H. rostratus across the Seychelles is explained more by isolation-by-distance than by adaptation, the genetic-morphological incongruence for affinities of Frégate H. rostratus might be caused by local adaptation over-riding the signal from their vicariant history. Our findings highlight the need of integrative approaches to investigate fine-scale geographic structuring to uncover underlying diversity and to better understand evolutionary processes on ancient, continental islands.
    • Saharan sand and dust storms and neonatal mortality: Evidence from Burkina Faso

      Karimi, Seyed M; Pouran, Hamid; Majbouri, Mahdi; Moradi-Lakeh, Maziar; Hakimian, Hassan; Basart, Sara (Elsevier, 2020-04-29)
      West African populations are exposed to the longest and harshest dust storms on the planet, the Saharan sand and dust storms (SDS). Nonetheless, little is known about the effects of the severe storms on early-life health in West Africa. This study investigated the association of the risk of neonatal mortality, an indicator of the population's early-life health, with potential prenatal and neonatal exposure to the Saharan SDS. Data on 30,552 under-five children from Burkina Faso's 1993, 2003, and 2010 demographic and health surveys were matched to the particulate matters (PM) and terrestrial air temperature and precipitation forecasts. Exposure to dust events was measured by the number of days with average PM10 and PM2.5 concentrations above a series of threshold. Intensity-dependent patterns of associations between neonatal mortality and both prenatal and birth month exposure to dust events were identified. There was no association if average daily PM10 and PM2.5 levels were <60 and 30 μg/m3, respectively. However, strong associations, which increase almost linearly with the intensity of exposure, were identified when daily PM10 and PM2.5 levels ranged between 70 and 150 and 40–70 μg/m3, respectively. At the higher PM levels, the association for the gestation period decreased, but that for the birth month remained mostly unresponsive to changes in the PM levels. Larger associations were identified when siblings were compared.
    • Salivary cortisol and cortisone responses to tetracosactrin (synacthen)

      Cornes, Michael P; Ashby, Helen L; Khalid, Yasmeen; Buch, Harit; Ford, Clare; Gama, Rousseau; Department of Clinical Chemistry, Royal Wolverhampton NHS Trust, Wolverhampton, UK michael.cornes@nhs.net. (SAGE Publications, 2015-01-01)
      © 2015, © The Author(s) 2015. Background To establish cutoff values for salivary liquid chromatography tandem mass spectroscopy cortisol and cortisone in defining adequate adrenocortical function during a standard synacthen test. Methods We compared salivary liquid chromatography tandem mass spectroscopy cortisol and cortisone responses to those of serum cortisol measured on the Roche E170 immunoassay analyser and the Abbott Architect i2000 before and 30 min and 60 min following 0.25 mg of intravenous synacthen. Results Correlations of salivary cortisol and cortisone were bimodal and linear, respectively. Based on these correlations, adequate salivary cortisol and cortisone responses to synacthen were extrapolated from a serum cortisol (Roche) cut-off of 550 nmol/L and defined as 15 nmol/L and 45 nmol/L, respectively. The Abbott method correlated well with the Roche but gave results that were about 20% lower than the Roche method. Conclusions Measurement of salivary cortisol and cortisone responses offers an alternative to those of serum cortisol during a synacthen test in the investigation of adrenal hypofunction.
    • Sample quantiles corresponding to mid p-values for zero–modification tests

      Wilson, Paul; Einbeck, Jochen; Grzegorczyk, Marco; Ceoldo, Giacomo (Statistical Modelling Society, 2017-07-03)
      Wilson and Einbeck (2015, 2016) propose a test for zero-modification relative to a stated model. The basis of the test is that the number of observed zeros follows a Poisson-binomial distribution. The decision to reject, or otherwise, the non zero–modified model is made by either (i) computing the mid p-value corresponding to the number of observed zeros, or (ii) comparing the number of observed zeros to the relevant “traditional” quantile of the appropriate Poisson–binomial distribution. In general either approach will result in the same decision, but occasionally discrepancies may occur. In this paper we investigate the use of mid-distribution quantiles in approach (ii) above, and show that this reduces the possibility of discrepancies.
    • Sampling and analysis of animal scent signals

      Walker, David; Vaglio, Stefano (MYJoVE Corporation, 2021-02-13)
      We have developed an effective methodology for sampling and analysis of odor signals, by using headspace solid-phase microextraction coupled with gas chromatography-mass spectrometry, to understand how they may be used in animal communication. This technique allows the semi-quantitative analysis of the volatile components of odor secretions by enabling the separation and tentative identification of the components in the sample, followed by the analysis of peak area ratios to look for trends that could signify compounds that may be involved in signaling. The key strengths of this current approach are the range of sample types that can be analyzed; the lack of need for any complex sample preparation or extractions; the ability to separate and analyze the components of a mixture; the identification of the components detected; and the capability to provide semi-quantitative and potentially quantitative information on the components detected. The main limitation to the methodology relates to the samples themselves. Since the components of specific interest are volatile, and these could easily be lost, or their concentrations altered, it is important that the samples are stored and transported appropriately after their collection. This also means that sample storage and transport conditions are relatively costly. This method can be applied to a variety of samples (including urine, feces, hair and scent-gland odor secretions). These odors consist of complex mixtures, occurring in a range of matrices, and thus necessitate the use of techniques to separate the individual components and extract the compounds of biological interest.
    • SARS-CoV-2, influenza virus and nanoscale particles trapping, tracking and tackling using nanoaperture optical tweezers: A recent advances review

      Kumar, Rajiv; Gulia, Kiran; Chaudhary, M.P.; Shah, M.A. (iScienceIn Publishing, 2020-12-02)
      Recent advances in nanoscale technologies have provided advanced tools that can be easily used to trap, track, and manipulate individual nanoscale particles and viruses such as severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) and influenza viruses accurately. Among the promising strategies that exist to date, optical forces based techniques are the leading tools in this task. Perfectly, focused lasers act as “optical tweezers,” and can trap individual particles and viruses. These forces can be applied to study nanomaterials, viruses, the building blocks of a quantum computer, and collision processes occurring between molecules in a better way than ever before. These cutting-edge tools are capable of trapping, tracking, and manipulating at the nanoscale in three dimensions. The optical tweezers have been used within biological and nanotechnological fields for trapping, tracking, and manipulating nanoparticles, and viruses with high flexibility, precision, and integration. The outcomes are important breakthroughs in the field of molecular mechanics. Here, we review the state-of-the-art optical tools employed in optical trapping, tracking, and manipulation of different particles at the nanoscale. The trapping of nanoparticles down to single-digit nanometer range and individual SARS-CoV-2 are the main features discussed here. Optical tweezers are also capable of sizing and probing acoustic modes of a small virus such as SARS-CoV-2 and influenza. The optical tweezers can perform tracking of nanoparticles in three-dimensional with high-resolution by forwarding scattered light. Optical tweezers are used to grab single molecules and measure events that are occurring and employed for measuring forces and measuring distance. A miniature and modular system creates a reliable and mobile optical trap that has more potential to be applied in optical trapping technologies.
    • Satellite-5G integration: a network perspective

      Giambene, Giovanni; Kota, Sastri; Pillai, Prashant (IEEE, 2018-09-27)
      Future 5G mobile communication systems are expected to integrate different radio access technologies, including the satellite component. Within the 5G framework, the terrestrial services can be augmented with the development of HTS systems and new mega-constellations meeting 5G requirements, such as high bandwidth, low latency, and increased coverage including rural areas, air, and seas. This article provides an overview of the current 5G initiatives and projects followed by a proposed architecture for 5G satellite networks where the SDN/NFV approach facilitates the integration with the 5G terrestrial system. In addition, a novel technique based on network coding is analyzed for the joint exploitation of multiple paths in such an integrated satellite-terrestrial system. For TCP-based applications, an analytical model is presented to achieve an optimal traffic split between terrestrial and satellite paths and optimal redundancy levels.
    • Seasonal variation and municiple solid waste composition—issues for development of new waste management strategies in Abuja, Nigeria

      Roberts, Clive L.; Watkin, Glynne; Ezeah, Chukwunonye; Phillips, Paul S.; Odunfa, Amos (Widener University School of Engineering and the National Center for Resource Management and Technology at the University of Pennsylvania, 2010)
      The state of solid waste management in cities of developing countries like Nigeria is a major social/environmental challenge. While research to understand the nature of the barriers to sustainable management methods have been carried out, the impact of seasonal changes in waste composition and practice is still in its infancy in developing countries. This paper investigates seasonal variation in municipal solid waste composition in Abuja, Nigeria, a classic tropical urban environment. Weekly waste collections from eighty randomly selected dwellings in Garki District of Abuja Municipality were sampled and analyzed at two peaks of the main tropical seasons: January-February (dry season) and August-September (wet season) in 2008. Results of compositional analysis and physical characterization were statistically analyzed and indicate that waste stream has approximately 11% and 60% recyclable and biodegradable components respectively. This investigation finds no significant difference in the proportion of biodegradable components of the waste stream from both seasons. Findings from this investigation helped develop strategies designed to improve current management practices.
    • Secukinumab efficacy and safety: Reporting on the experiences of clinicians and patients

      Al Abadie, Mohammed; Ayaz, Ambreen; Adcock, Lyn; Elston, Georgina; Beswick, Samantha; Cartwright, Peter; Ibrahim, Rangeen; Ball, Patrick; Morrissey, Hana (Research Trends, 2019-09-07)
      Secukinumab (SEC) is a human monoclonal antibody that selectively neutralizes IL-17A, a key cytokine involved in the development of psoriasis. Superior efficacy has been demonstrated in clinical trials with up to 79% of moderate-to-severe psoriasis patients achieving a PASI 90 at week 16 and 75% achieving a PASI 90 at week 52. However, the population recruited into clinical trials are different to the real-world population. The aim of this paper is to discuss the safety and efficacy of SEC based on ‘real-world data’ when used in patients with multiple co-morbidities and concomitant medications. Two clinical audits conducted were based on a clinical audit checklist, which was adopted and included in all patients’ usual care as the patient-management model for biological therapies. Patients on SEC were identified from our pharmacy database and data was collected from electronic patient records between September 2015 and May 2018. The psoriasis area severity index (PASI) and dermatology life quality index (DLQI) were extracted at baseline and at 16 weeks. The results from the rheumatology departments of the two hospitals were then compared. A total of 135 patients’ data was analysed. SEC was found to offer an efficacious real-world treatment option with response rates generally higher than observed in pivotal Phase III clinical trials. Response rates were higher in biologic naïve patients than non-naïve patients. There were no unusual safety signals; however, long-term efficacy and sustainability are yet to be established.
    • Securing the embeddedness of psychosocial diffusion indicators into the Turkish construction industry: Silence is no longer golden

      Goulding, JS; Ezcan, V; Sutrisna, M (Emerald, 2018-04-03)
      © 2018, Emerald Publishing Limited. Purpose: The paper aims to investigate the employee–stakeholder engagement on business performance. A psychosocial approach was used to evaluate employees’ perception and role engagement on organisational performance, cognisant of: strategy development; leadership; fiscal acuity; employees’ skills, empowerment; supply chain relationships; external stakeholders and wider societal beneficiaries. Design/methodology/approach: This research is context-bound to the Turkish construction industry. Findings generated from literature established a set of evidenced-based priorities for further investigation. A case study approach was conducted with three large architecture, engineering and construction (AEC) organisations to define psychosocial diffusion indicators and priorities for future uptake. Findings: Initial findings on psychosocial diffusion indicators and their impact on business performance are presented through a psychosocial diffusion model. Three interconnected facets are proffered for future uptake: capability (responsiveness), capability (flexibility) and capability (competence). Research limitations/implications: Findings are exclusively bound to the sample frame in question. No attempt has been made to undertake detailed cross-analysis/correlation to support internal/external consistency, validity or reliability. Practical implications: Organisations are able to reflect on their core business strategy to appreciate how psychosocial diffusion can be operationalised. Social implications: This work impinges on social factors embedded within (and across) organisational boundaries, including the AEC supply chain. It also relates to employer/employee relationships, psychological functioning and employee well-being. Originality/value: Originality rests with the identification of construction-related psychosocial indicators. It contributes to the wider body of knowledge on embedding psychosocial indicators into organisational systems and processes, adding further insight into systems thinking and business transformation.
    • Security and Privacy of Things: Regulatory Challenges and Gaps for the Secure Integration of Cyber-Physical Systems

      Lee, Geraldine; Epiphaniou, Gregory; Al-Khateeb, Haider; Maple, Carsten (Springer, 2018-02-27)
      The rise of interconnected “intelligent” objects that move their capabilities from sensing and data processing to decision-making will be a disruptive phenomenon that further widens the gaps between legal, regulatory and technological approaches. This research sets out to establish a guided roadmap through the maze of regulation by incorporating the fragmented governance efforts into a single focus where security and privacy gaps unique to Machine-to-Machine communication (M2M) are identified against key performance metrics. We use privacy, ethics, trust, legality, data sharing, operational integration and device and communication protocols as our key performance metrics to highlight areas of significant overlap and gaps in a comprehensive list of standards to assist policymakers and researchers in the field. Results also indicate that policy concerns and diffused responses from existing standards raise unacceptable risks for the cyber and physical spheres in the IoT preventing their integration with existing hierarchical security architectures and reducing the opportunities for mass-market economies of scale.
    • Security Aware Virtual Base Station Placement in 5G Cloud Radio Access Networks

      Sigwele, T; Pillai, P; Sangodoyin, A; Hu, YF (Springer International Publishing, 2018-03-08)
      © 2018, ICST Institute for Computer Sciences, Social Informatics and Telecommunications Engineering. In fifth generation (5G) cloud radio access networks (C-RAN), baseband processing of base stations (BS’s) will be processed on virtual machines called virtual BSs (VBS) in the centralized cloud architecture. The existing researches mostly focus on how to maximize resource utilization and reduce energy consumption in 5G C-RAN using VBS placement. However, security issues in the context of VBS placement within 5G C-RAN have been rarely addressed. In this paper, a security aware VBS placement (SAV) scheme within 5G C-RAN is proposed where the placement of VBSs to physical machines (PMs) considers the security levels of both the VBS and the PM. A rigorous simulation study is conducted for validating the proposed scheme, which shows a significant security improvement of 16% compared to the heuristic simulated annealing scheme (HSA).
    • Seismic collapse of self-centering steel MRFs with different column base structural properties

      Kamperidis, VC; Papavasileiou, GS; Kamaris, GS; Vasdravellis, G (Elsevier, 2020-09-19)
      © 2020 Elsevier Ltd The effect of the strength and stiffness characteristics of a previously proposed novel column base on the seismic performance and collapse capacity of steel self-centering moment-resisting frames is evaluated in this paper. This is done through three normalised parameters that represent the initial stiffness, post-yield stiffness, and strength of the column base, which can be independently adjusted. For these evaluations, a prototype steel building, which serves as a case study, is designed with sixteen different cases of a self-centering moment-resisting frame with different column base stiffness and strength characteristics (SC-MRF-CBs). A self-centering moment-resisting frame with conventional column bases and the same members and beam-column connections as those of the SC-MRF-CBs, named SC-MRF, serves as a benchmark frame. A set of 44 ground motions was used to conduct non-linear dynamic analyses and evaluate the seismic performance of the frames. Incremental dynamic analyses were also performed with the same ground motions set to evaluate the collapse capacity of the frames. Collapse capacity fragility curves and adjusted collapse margin ratios of the frames were derived and used for the comparison of the seismic risk of the frames. The results show that the new self-centering column base significantly improves the seismic performance of the SC-MRF, demonstrating the potential of the SC-MRF-CBs to be redesigned with smaller member sections. Moreover, the SC-MRF-CBs achieve significant reduction in collapse risk compared to the SC-MRF. Finally, the results show that increasing the base strength and stiffness improves the seismic performance and collapse capacity of the SC-MRF-CBs.
    • Selective inhibition of plasma membrane calcium ATPase 4 improves angiogenesis and vascular reperfusion

      Kurusamy, Sathishkumar; López-Maderuelo, Dolores; Little, Robert; Cadagan, David; Savage, Aaron M; Ihugba, Jude C; Baggott, Rhiannon Rebecca; Rowther, Farjana B; Martínez-Martínez, Sara; Gómez-del Arco, Pablo; et al. (Elsevier, 2017-07-03)
      Aims Ischaemic cardiovascular disease is a major cause of morbidity and mortality worldwide. Despite promising results from pre-clinical animal models, VEGF-based strategies for therapeutic angiogenesis have yet to achieve successful reperfusion of ischaemic tissues in patients. Failure to restore efficient VEGF activity in the ischaemic organ remains a major problem in current pro-angiogenic therapeutic approaches. Plasma membrane calcium ATPase 4 (PMCA4) negatively regulates VEGF-activated angiogenesis via inhibition of the calcineurin/NFAT signalling pathway. PMCA4 activity is inhibited by the small molecule aurintricarboxylic acid (ATA). We hypothesize that inhibition of PMCA4 with ATA might enhance VEGF-induced angiogenesis. Methods and results We show that inhibition of PMCA4 with ATA in endothelial cells triggers a marked increase in VEGF-activated calcineurin/NFAT signalling that translates into a strong increase in endothelial cell motility and blood vessel formation. ATA enhances VEGF-induced calcineurin signalling by disrupting the interaction between PMCA4 and calcineurin at the endothelial-cell membrane. ATA concentrations at the nanomolar range, that efficiently inhibit PMCA4, had no deleterious effect on endothelial-cell viability or zebrafish embryonic development. However, high ATA concentrations at the micromolar level impaired endothelial cell viability and tubular morphogenesis, and were associated with toxicity in zebrafish embryos. In mice undergoing experimentally-induced hindlimb ischaemia, ATA treatment significantly increased the reperfusion of post-ischaemic limbs. Conclusions Our study provides evidence for the therapeutic potential of targeting PMCA4 to improve VEGF-based pro-angiogenic interventions. This goal will require the development of refined, highly selective versions of ATA, or the identification of novel PMCA4 inhibitors.
    • Self attended stack pointer networks for learning long term dependencies

      Tuç, Salih; Can, Burcu (Association for Computational Linguistics, 2020-12-31)
      We propose a novel deep neural architecture for dependency parsing, which is built upon a Transformer Encoder (Vaswani et al., 2017) and a Stack Pointer Network (Ma et al., 2018). We first encode each sentence using a Transformer Network and then the dependency graph is generated by a Stack Pointer Network by selecting the head of each word in the sentence through a head selection process. We evaluate our model on Turkish and English treebanks. The results show that our transformer-based model learns long term dependencies efficiently compared to sequential models such as recurrent neural networks. Our self attended stack pointer network improves UAS score around 6% upon the LSTM based stack pointer (Ma et al., 2018) for Turkish sentences with a length of more than 20 words.
    • Self-assembly of pH-sensitive fluorinated peptide dendron functionalized dextran nanoparticles for on-demand intracellular drug delivery.

      Ma, Shengnan; Zhou, Jie; Wali, Aisha Roshan Mohamed; He, Yiyan; Xu, Xianghui; Tang, James Zhenggui; Gu, Zhongwei (2015-08)
      In this study, the amphiphilic fluorinated peptide dendrons functionalized dextran (FPD-HZN-Dex) via an acid-sensitive hydrazone linkage was successfully designed and prepared for the first time. We demonstrated a spontaneous self-assembly of amphiphilic FPD-HZN-Dex into the well-defined nanoparticles with the core-shell architecture in aqueous media, which is attributed to the efficient amphiphilic functionalization of dextran by the hydrophobic fluorinated peptide dendrons. The spherical morphology, uniform particle size and good storage stability of the prepared FPD-HZN-Dex nanoparticles were characterized by dynamic light scattering and transmission electron microscopy, respectively. In vitro drug release studies showed a controlled and pH dependent hydrophobic drug release profile. The cell viability assays show excellent biocompatibility of the FPD-HZN-Dex nanoparticles for both normal cells and tumor cells. Moreover, the FPD-HZN-Dex self-assembled systems based on pH-sensitive hydrazone linkage also can serve as stimulus bioresponsive carriers for on-demand intracellular drug delivery. These self-assembled nanoparticles exhibit a stimulus-induced response to endo/lysosome pH (pH 5.0) that causes their disassembly over time, enabling controlled release of encapsulated DOX. This work has unveiled a unique non-covalent interaction useful for engineering amphiphilic dendrons or dendrimers self-assembled systems.
    • Self-healing polymers synthesized by Ring Opening Metathesis Polymerization (ROMP) of bio-derived furanic molecules

      Keddie, Daniel; Naguib, Mohamed; Rashed, Atteya (Springer Nature, 2021-02-09)
      Novel bio-derivable tricyclic oxanorbornene polymers, based upon secondary furfurylamine and maleic anhydride derived monomers, prepared via ring opening metathesis polymerization (ROMP) are reported. The tricyclic oxanorbornenes with fused lactam ring are exo Diels–Alder adducts. DFT calculations support the cycloaddition is the first step followed by lactamization. The polymerizations are rapid and deliver polymers with targeted molar mass and low dispersity (Đ). The prepared polymers with furanyl pendant groups have reactivity toward maleimide-bearing compounds to form thermally induced crosslinked networks through thermoreversible Diels–Alder reactions. The thermoreversible (self-healing) behavior is confirmed by sol gel transition. This new class of bio-derived polymer could be further modified with different active moieties as pendant groups and hence be tailored for more applications in the future.