• Time-dependent thixotropic behaviours of lead-free Sn-Ag-Cu (SAC) solder pastes and flux mediums used in electronic assemblies

      Mallik, S; Ekere, Nduka; Depiver, Joshua (David Publishing, 2022-12-31)
      Solder pastes are widely used as crucial joining material in microelectronic assemblies. This study investigates time-depended behaviours of paste materials (solder pastes and flux mediums) in relation to their transportation, storage, handling and applications. Two fluxes and four commercially available lead-free solder pastes prepared from those fluxes were evaluated. Two rheological test methods – ‘hysteresis loop test’ and ‘step shear test’ were adapted, taking account of actual shear profile of solder pastes and flux mediums. Within hysteresis loop tests, samples were sheared for both single and multiple cycles, with increasing and decreasing shear rates. These tests provided a quick and straightforward way of benchmarking time-depended structural breakdown and build-up of paste materials. The test results also provided an effective means of predicting how the pastes will behave during their use, such as at various stages of the stencil printing process. Step shear tests were performed by applying a sequence of stepwise increase in shear rates. The step-wise increase in shear rate has influenced the timedependent behaviours of solder paste samples and flux mediums. The result from the stepshear-test implies that the build-up of solder paste structure depends mainly on both the previous shear history and the intensity of structural break-down.
    • The impact of disruptive events on built environment degree apprenticeship delivery - A case study of COVID-19

      Oloke, David; Gyoh, Louis; Daniel, Emmanuel Itodo; Oladinrin, Olugbenga Timo; Abdallah, Nagwan (Emerald, 2022-12-31)
      Purpose: This study aims to understand the impact of the covid-19 pandemic disruptive event on delivery of the built environment degree apprentice programme in higher education in the UK and identify the key strategies to minimise the effect. Design/methodology/approach A qualitative approach was used to collect and analyse data from a sample set of built environment degree apprenticeship stakeholders. Semi-structured interviews was conducted with seventeen key stakeholders to collate emerging themes on their perceptions of the impacts of the pandemic and strategies to adopted to minimise it. Findings: The investigation reveals that the core impacts of covid-19 on the apprentices training programme are lack of access to the site, furlough, limited access to off the job training, limited interaction with tutors and peers, too much time on the screen, limited pastoral care and lack of contact with a mentor. The census from the research participants is that despite the development and gain with the various virtual platform used during pandemic physical meetings with their mentor remain pivotal to the built environment apprentices learning and training. Practical implications: The results provide relevant stakeholders and actors supporting degree apprentices training programmes (training providers and employers, among others) with the information needed to improve the delivery of Built Environment degree apprenticeship training programmes during a disruptive event covid-19. Originality: The principal scientific significance of the current study to education and training in the built environment lies in its presentation of empirical evidence on the impact of the covid-19 pandemic on degree apprentice's programme in the built environment and strategies to minimise the effect, which has not been documented.
    • A Brief guide to polymerization terminology (IUPAC Technical Report)

      Luscombe, Christine K; Moad, Graeme; Hiorns, Roger C; Jones, Richard G; Keddie, Daniel J; Matson, John B; Merna, Jan; Nakano, Tamaki; Russell, Gregory T; Topham, Paul D (Walter de Gruyter, 2022-12-31)
      Introduction. The use of self-consistent terminology to describe polymerizations is important for litigation, patents, research and education. Imprecision in these areas can be both costly and confusing. To address this situation the International Union of Pure and Applied Chemistry (IUPAC) has made recommendations, which are summarized below. References and hyperlinks lead to source documents. Screen tips contain definitions published in IUPAC recommendations.
    • Evaluating the effects of indoor air quality on teacher performance using artificial neural network

      Alzahrani, Hamdan; Arif, Mohammed; Kaushik, Amit; Rana, Muhammad Qasim; Aburas, Hani (Emerald, 2022-12-31)
      Purpose - Indoor Air Quality has a direct impact on occupant health and productivity. Understanding the effect of Indoor Air Quality (IAQ) in educational buildings is essential in both the design and construction phases for decisionmakers. Hence, it is equally important to recognise and appreciate the influence of design judgements on occupants' performance, especially on teacher and students. Design - This study aims to evaluate the effect of IAQ on teachers' performance. This study would deliver air quality requirements to BIM-led school projects. the methodology of the research approach uses quasi-experiment using questionnaire surveys and physical measurements of indoor air parameters to associate correlation and deduction. A technical college building in Saudi Arabia was used for the case study. The study developed an Artificial Neural Network model to define and predict relationships between teachers' performance and indoor air quality. Findings - This paper highlights a detailed investigation into the impact of indoor air quality via direct parameters (relative humidity, ventilation rates and carbon dioxide) on teacher performance. Research findings also indicate an optimal relative humidity with 65%, ranging between 650 ppm to 750 ppm of CO2, and 0.4m/s ventilation rate. This ratio considered optimum records for both comfort and performance. Originality – This paper focused on teachers’ performance in Saudi Arabia and used Artificial Neural Networks to define and predict the relationship between performance and indoor air quality. There are few studies focusing on teachers’ performance in Saudi Arabia and very few that uses ANN in data analysis.
    • Terminology for chain polymerization (IUPAC Recommendations 2021)

      Fellows, Christopher M; Jones, Richard G; Keddie, Daniel; Luscombe, Christine K; Matson, John B; Moad, Graeme; Matyjaszewski, Krzysztof; Merna, Jan; Nakano, Tamaki; Penczek, Stanislaw; et al. (Walter de Gruyter, 2022-12-31)
      Chain polymerizations are defined as chain reactions where the propagation steps occur by reaction between monomer(s) and active site(s) on the polymer chains with regeneration of the active site(s) at each step. Many forms of chain polymerization can be distinguished according to the mechanism of the propagation step (e.g., cyclopolymerization – when rings are formed, condensative chain polymerization – when propagation is a condensation reaction, group-transfer polymerization, polyinsertion, ring-opening polymerization – when rings are opened), whether they involve a termination step or not (e.g., living polymerization – when termination is absent, reversible-deactivation polymerization), whether a transfer step is involved (e.g., degenerative transfer polymerization), and the type of chain carrier or active site (e.g., radical, ion, electrophile, nucleophile, coordination complex). The objective of this document is to provide a language for describing chain polymerizations that is both readily understandable and self-consistent, and which covers recent developments in this rapidly evolving field.
    • Business model innovation for Industry 4.0 agenda

      Jallow, Haddy; Renukappa, Suresh; Suresh, Subashini (Business Model Society, 2022-12-31)
      The manufacturing industry is currently within the fourth industrial revolution. The term “Industry 4.0” refers to the automation and digitisation of the manufacturing industry with new technologies emerging. The UK infrastructure sector currently have many projects on going, upgrading existing assets and constructing new assets. Despite being in the fourth industrial revolution, the infrastructure sector is finding it difficult to adopt and implement industry 4.0 agenda as there is no direct guide or standards available for implementation, in addition organisations within the sector do not understand the requirements and competency level. This paper aims to outline the need for business model innovation within the sector to enable the adoption and implementation of industry 4.0 agenda. This study takes a case study approach and semi-structured interviews were undertaken from experts in the infrastructure sector to analyse the need for Business model innovations within the sector.
    • Becoming better: Facilitating equality, diversity and inclusion in teaching and learning through intersectionality lens

      Suresh, Subashini; Sarrakh, Redouane; Mondokova, Andrea; Renukappa, Suresh; Karodia, Nazira; Adage, Ada (British Academy of Management, 2022-09-02)
      This developmental paper introduces a case study currently being conducted at a university in the United Kingdom. Mixed-methods research seeks to glean an understanding of students’ awareness of intersectionality, explore their experiences of current intersectional practices in teaching and learning within the institution, and recognise how these differ across the institutional faculties and departments. Following the data collection and analysis phase, the project aims to improve and increase the awareness and understanding of the topic of intersectionality in the HE setting, to aid students’ exploration of sense of self-identity and increase their understanding of identities of those around them. Finally, using a holistic approach, the project intends to help create awareness of intersectionality and its practices in teaching and learning across the institution so that all staff and students benefit from inclusive HE environment.
    • Impact of sustainability strategies on the Qatar oil and gas sector

      Sarrakh, Redouane; Renukappa, Suresh; Suresh, Subashini (British Academy of Management, 2022-09-02)
      Qatar had experience an unprecedent economic growth since the discovery of its fossil fuel reserves back in the 1990s. However, this economic growth had been accompanied by an unsustainable consumption of energy resources amongst citizens and organisations alike. Therefore, the Qatar government decided to follow up the footsteps of the rest of the world by adapting sustainability policies, which was in the form of Qatar National Vision 2030 in 2008. The oil and gas sector, and much like the rest of the sectors in Qatar urged for the implementation of sustainability strategies in order adopt the country’s vision at the organisational level through the Qatar Energy and Industry Sustainability Strategy in 2011. Although the QEISS has been introduced a while back, some organisations within the sector are still doubtful of the importance of sustainability initiatives to their future and the future of Qatar. This is the raison d’être of this paper, as it looks to highlight the impact of sustainability initiatives on Qatar oil and gas organisations. The paper follows a qualitative approach, interviewing 24 professionals from eight different Qatar oil and gas organisations. Thematic analysis has been adopted as the data analysis process. The study is currently at the data analysis stage. The preliminary findings of the paper note that organisations economic, environmental and social performances improve with the implementation of sustainability initiatives.
    • Techniques and technologies for managing COVID-19 related knowledge: A systematic review

      Abdalla, Wala; Renukappa, Suresh; Suresh, Subashini; Al-Meraikhi, Hamda Salem; Algahtani, Khaled (Academic Conferences International, 2022-09-02)
      Managing COVID-19 pandemic outbreak requires rapid responses, adapting to change, and developing a set of ongoing, systematic, and interrelated processes to improve the planning, treatment and controlling the pandemic. Knowledge management (KM) is considered one of the instruments that helps organizations and supports managers in making effective use of key resources and in identifying actionable problem-solving knowledge and practice. Thus, it is vital to conduct appropriate KM activities to facilitate effective decision-making efforts., Advanced technologies have made significant contribution to improving the KM processes and provided several tools and mechanisms to enable and facilitate knowledge capturing, sharing, and transfer. With this in mind, the aim of this paper is to explore the techniques and technologies used for managing COVID-19 related knowledge. The findings are in the main, based a systematic review of literature. The findings report on the importance of KM techniques and technologies for managing COVID-19 related knowledge. The study concluded that KM techniques and technologies played vital role during COVID-19 in facilitating distance working/ learning, combating “infodemic”, promoting knowledge share and transfer, facilitating collective /innovation, and in facilitating remote mentoring and training. Social media platforms (e.g., Twitter, Facebook, WhatsApp, etc.), Zoom, MS Teams, Virtual Meeting, Video Conferencing, as well as Email and knowledge maps are among the most used knowledge management techniques and technologies used to manage COVID-19 related knowledge. The paper concludes that to gain competitive advantage, it is necessary for organisations to recognise and use a blend of information and communication technology (ICT) and non-ICT-based KM techniques and technologies. KM techniques and technologies roles are not mutually exclusive, and organisations may adopt any combination of them to tackle their particular issues or support particular motives. Therefore, it is recommended to deploy and combine the simple, low cost, and easy to use with minimum training needs KM techniques and technologies.
    • Evaluation of the role of artificial intelligence in delivering smart cities

      Griffiths, Kelly; Renukappa, Suresh; Suresh, Subashini; Mora, Luca (British Academy of Management, 2022-09-02)
      Smart Cities are having to find new techniques to deal with the increasing urbanisation situation in already overpopulated areas. A potential and developing solution is the use of artificial intelligence (AI) to enable these cities to tackle and overcome problems caused as a result of urbanisation. The objective of this review is to identify the breakdown of the different components of a smart city and understand published literature to identify and compile the impact artificial intelligence has on these 6 smart city attributes: smart economy, smart people, smart governance, smart mobility, smart environment and smart living. Artificial intelligence can have a number of potential positive impacts on Smart City evolvement and growth such as, education, public services, reduced travel times, intelligence and surveillance, increase energy efficiency and healthcare to name a few. It could however lead to a number of negative effects in unemployment, liability factor, trust, limited legislations, lack of emotive state and ethics and data breaches. Ultimately, the general public’s uncertainty, concern and general lack of understanding of the potential impacts of AI are obstructing its full use and potential, most of this stems from the lack of information given to the public regarding the future uses and potential AI brings. Further research needs to be carried out to fully understand the public’s concern to allow an action plan to be produced to ensure the public are on board with the implementation of AI. Without the public’s acceptance AI will not flourish and smart cities will not be able to cope with the increase of urbanisation.
    • How the UK transportation sector can achieve net carbon zero using building information modelling

      Manifold, Joel; Renukappa, Suresh; Suresh, Subashini; Georgakis, Panagiotis (British Academy of Management, 2022-09-02)
      The United Kingdom (UK) Transportation Sector (TS) does not currently align with the governments’ wider Net Carbon Zero (NCZ) approach. The Architecture, Engineering and Consulting (AEC) industries are anticipating strong growth over the coming decades and require more modern, digital approaches to design and planning to help reduce carbon emissions as well as improving carbon across project lifecycles. Building Information Modelling (BIM) processes are still seen to be in an infancy stage with regards to implementation on TS projects across the UK. However, The UK Governments BIM mandate has encouraged and increase the utilisation of BIM within the TS with studies demonstrating the positive effects BIM has by improving workflows efficiency, early identification of carbon hotspots within a project and more accurate understand of where design efficiencies can lead to a reduction in carbon emission. The purpose of this paper is to understand the current usage of BIM within the UKs TS and how general BIM practises and workflows can help contribute towards the NCZ approach, echoed by the UK Government. A systematic Literature Review approach has been conducted with the research question formed deriving from the Population, Intervention, Comparison and Outcome (PICO) system. In addition to this, inclusion and exclusion criteria to screen irrelevant information and help streamline research documents. After screening the relevant information, 18 pieces of literature reviewed were reviewed and helped identify six key drivers within this review such as Carbon reduction and BIM, BIM in Transportation Design, BIM uptake and usage in Transportation, BIM in Transportation Construction and Digital Twins and BIM. The conclusion of this review suggests uptake in of BIM in the TS is low in relation to other sectors and further research is required to demonstrate the potential for BIM workflows to help further align the TS with the UKs NCZ policy.
    • Industry 4.0 application adoption and implementation in UK infrastructure sector: Change management strategies

      Jallow, Haddy; Renukappa, Suresh; Suresh, Subashini; Al-Meraikhi, Hamda Salem (British Academy of Management, 2022-09-02)
      There has been a major focus on the improvement of productivity within the infrastructure sector through the use of Internet of Things (IOT) and Information and Communication Technology (ICT). These concepts have been proven to reduce the time of processing data while enhancing the communication between the parties within the organisation overall improving productivity. There has been plentiful research on modern technologies and processes such as the Building Information Model (BIM) which has indicated a promising method of positively influencing the cost issues through taking advantage of the constructions design. The UK government has invested a great amount into the UK infrastructure over the next couple of years, with this investment, standards were set by the Government which led to the introduction of the Building Information Model plus more strategic automated processes within the industry. Despite automated processes being introduced, the infrastructure sector are still yet to fully adopt and implement Industry 4.0 applications. There has been a number of publications on the topic Industry 4.0, however its relation to the infrastructure sector has a major lack of research. For this research study, case study methodology approach was adopted as there is lack of academic research on the topic. Ten semi-structured interviews were undertaken and a total number of five organisations took part in this study. Clients have been increasingly asking for more automated processes in order to increase efficiencies and improve productivity which is a benefit for them. One of the main key change management strategies adopted found in this research is training and upskilling of staff within the industry. It is concluded that he industry as a whole should implement Business models for their organisations highlighting key Industry 4.0 agenda and adoption and implementation guidance.
    • Challenges for adoption of smart healthcare strategies: An Indian perspective

      Subbarao, Chandrashekar; Renukappa, Suresh; Suresh, Subashini; Menon, Shyam (British Academy of Management, 2022-09-02)
      Smart healthcare management strategies have shown great promise in delivering the best quality healthcare to all and is the best possible solution to address the challenges in meeting the goal of quality healthcare to all. The Indian Government has set out ambitiously in this regard through the Ayushman Bharath Digital Mission (ABDM) which “aims to develop the backbone necessary to support the integrated digital health infrastructure of the country”. As this flagship project is rolled out, it is important to understand the various challenges to the successful uptake of this mission. The objective of this review is to systematically examine published literature to identify and compile a list of such challenges. The knowledge of such challenges is critical to make the ABDM successful. EBSCOHost, PubMed, Scopus, Science Direct and Open Access databases were systematically searched for full text, peer reviewed, English articles that have listed such challenges in the adoption of smart healthcare. In addition to these searches, the ABDM portal and the document store have also been used for analyses since the scope for this review is India. The Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines were used to select eligible articles. After the full screening,12 articles that met the criteria were analysed and used to identify 11 key challenges for adopting smart healthcare management strategies. Identified challenges will enable Indian health sector policy makers and healthcare leaders to understand and accurately evaluate potential solutions of adopting ABDM strategies. It is important to emphasise that the success of ABDM is dependent on its adoption by public and private sector entities and by individuals and decision makers. It is concluded that future research is needed in identifying key smart healthcare management strategies and key drivers for adopting smart healthcare management strategies.
    • Digital innovations for infrastructure asset management: A case of the railway sector

      Seabright, Luke; Renukappa, Suresh; Suresh, Subashini; Hiremath, Rahul; Stride, Mark (British Academy of Management, 2022-09-02)
      Infrastructure asset management in the UK railway sector, is subject to an evolving practice of digitisation. Digitising asset management in the UK railway sector is challenging, with the adaptation of digital strategies posing highly beneficial outcomes providing all systems align. The current effort to adapt is met with challenges including the ability to integrate systems using smart technologies, accountability, upskilling and recruitment, standardisation, and absence of a transformational strategy incorporating all aspects of digital innovations for infrastructure asset management. The objective of this review is to use published literature to provide a collative understanding on the status of digital asset management technologies and strategies. This will enable further research areas to be identified, along with recommendations to improve the transformation from traditional asset management strategies to digital asset management strategies.
    • Challenges for managing knowledge in post-pandemic universities and higher education institutions

      Abdalla, Wala; Renukappa, Suresh; Suresh, Subashini; Starr, Sean; Karodia, Nazira (British Academy of Management, 2022-09-02)
      Impact of COVID-19 is evident in all aspects of life, from economy, health, transportation, to education and personal lifestyle. In reaction to the devastating impacts of this pandemic, various strategies were introduced to reduce interpersonal contact and control the virus spread including lockdown and social distancing. COVID-19 pandemic accelerated the movement decisively toward the “digital transformation” and into a more digital society. Hence, online education, including eLearning and distance learning strategies, and other technology-based education strategies have been implemented as they were the only options for the continuation and completion of the academic year even though neither teachers nor students were fully prepared for this shift. The aim of this paper is to explore the impact of COVID-19 on universities and higher education institutions, and the role of knowledge management in managing change during the pandemic and in preparing better for post-pandemic. A critical review of the literature was conducted to achieve this aim. The findings revealed the impact of COVID-19 on universities and higher education and its associated opportunities and challenges. The findings also highlighted importance of knowledge management strategies in addressing those challenges and preparing better for the future.
    • Evaluation of sustainable business model innovation impacts for organisations: an application of the value mapping tool

      Martinez Volquez, Gabriel; Renukappa, Suresh; Suresh, Subashini (British Academy of Management, 2022-09-02)
      Creating and delivering economic, social and environmental value has become a priority for businesses around the world. Organisations that pursue sustainable business model innovation aim to contribute to the three pillars of sustainability by developing processes and capabilities to identify emerging opportunities, capitalise on those opportunities, engage with stakeholders, or adapt to changing circumstances. Thus, value creation help sustainable business models to increase their competitive advantage while ensuring resilience. The aim of this paper is to explore the impact of these activities. A qualitative enquiry based on semi-structure interviews allowed to expand current discussion and could help identify emerging themes. A design thinking value mapping tool is applied to present the findings and discuss avenues of value creation. The tool if often associated with ideation of sustainable business models, however, literature recognise its potential for the evaluation of their impact.
    • The physiological and phenotypic response of Salvia aethiopis L. to herbicides

      Mousavimanesh, Nafisehsadat; Karimmojeni, Hassan; Vaghar, Moslem; Baldwin, Timothy (Elsevier, 2022-08-09)
      Salvia aethiopis is an aromatic species within the Lamiaceae family, used both as a herb and as an ornamental plant, the yield and quality of which, when cultivated on a commercial basis, is frequently affected by weed infestation. Therefore, the application of herbicide is often required for the commercial production of this species. Considering which, for the current study, a pot experiment based upon a completely randomized design, with three replications, was conducted to evaluate the physiological and growth response of S. aethiopis to five commonly used herbicides (bentazon, phenmedipham/desmedipham, metribuzin, oxyfluorfen and oxadiargyl). These herbicides were applied at three concentrations (0.75X, 1X and 1.25X where X is equal to the recommended dose of herbicide). The data obtained from this study, demonstrated that herbicide application led to an increase in crop damage, minimum fluorescence (F0) and malondialdehyde content (MDA) and a concomitant decrease in the maximum quantum efficiency of PSΙΙ (FV/FM), maximum fluorescence (FM), SPAD value, relative water content (RWC), plant height and shoot and root dry weight as compared to the control. However, the level of response/tolerance was dependent upon the specific herbicide and the dose applied. Of the selected herbicides, S.aethiopis has shown to display the most tolerance to bentazon. As such, these data indicate that of the herbicides tested, bentazon should be the preferred herbicide used for broad leafed weed control, during the commercial production of this species.
    • Shelf-life prediction and thermodynamic properties of no added sugar chocolate spread fortified with multiple micronutrients

      Tolve, Roberta; Tchuenbou-Magaia, Fideline Laure; Sportiello, Lucia; Bianchi, Federico; Radecka, Iza; Favati, Fabio (MDPI, 2022-08-06)
      The development of fortified healthy pleasant foods, in which saturated fats are replaced with unsaturated ones, poses a challenge for the food industry due to their susceptibility to oxidative rancidity, which decreases product shelf-life, causes the destruction of health-promoting molecules, and forms potentially toxic compounds. A comparative study applying the Arrhenius model was carried out to investigate the oxidative stability and predict the shelf-life of a newly developed no added sugar chocolate spread formulated with sunflower oil, and fortified with vitamin D, Mg, and Ca checked against two commercially available spreads: No Palm and a well-known commercially available product (RB). The results obtained from the accelerated shelf-life testing for peroxide value (PV) showed relatively higher activation energy (Ea, 14.48 kJ/mol K) for RB, whereas lower Ea (11.31–12.78 kJ/mol K) was obtained for No Palm and all the experimental spread chocolates. Q10 values were comparable (1.202–1.154), indicating a similar catalytic effect of the temperature upon the oxidation rate across all the investigated samples. The positive Gibbs free energies ranged from 75.014 to 83.550 kJ/mol and pointed out that the lipid oxidation reaction in the chocolate spread was an endergonic process. The predicted shelf-life at 293.15 K was 8.57 months (RB), 7 months (No Palm), and 6.8 months for all the experimental spreadable chocolate. However, the higher production of hydroperoxides was observed in chocolate fortified with magnesium-calcium carbonate nanoparticles and stored at 313.15 and 323.15 K, suggesting these particles may enhance lipid oxidation.
    • Anogenital scent-marking signals fertility in a captive female Alaotran gentle lemur

      Fontani, Sara; Kaburu, Stefano; Marliani, Giovanna; Accorsi, Pier Attilio; Vaglio, Stefano (Frontiers Media, 2022-07-28)
      The Lake Alaotra gentle lemur (Hapalemur alaotrensis) is one of the 25 most endangered primates in the world and shows low success rate in captive breeding programmes. It is therefore vital to further understand its reproductive biology. We studied a captive troop consisting of five individuals hosted at Jersey Zoo during breeding and non-breeding periods over one year. We collected behavioural data (n=318 hours) using all occurrences of some behaviours and ad libitum sampling methods, as well as faecal (n=54) and anogenital scent (n=35) samples of the breeding female. We measured sex hormone levels using enzyme immunoassay technique and investigated the volatile component of odour signals using solid-phase microextraction and gas chromatography-mass spectrometry. We observed sexual and aggressive behaviours occasionally during the breeding period. Our regression analysis showed that only period significantly predicted rates of female anogenital scent-marking, whereby the female performed anogenital scent-marking more frequently during the breeding rather than the non-breeding period. In contrast, female hormone levels did not significantly explain variation in rates of neither male nor female olfactory, sexual and affiliative behaviours, suggesting that individuals’ behaviour alone is not an effective indicator of the ovulation window. The volatile chemical profile of anogenital odour secretions changed over the study, with four compounds distinguishing the fertile window during the breeding period. In conclusion, our findings suggest that anogenital scent-marking may signal the reproductive status of captive female gentle lemurs.
    • Microbial poly-γ-glutamic acid (γ-PGA) as an effective tooth enamel protectant

      Parati, Mattia; Clarke, Louisa; Anderson, Paul; Hill, Robert; Khalil, Ibrahim; Tchuenbou-Magaia, Fideline Laure; Stanley, Michele S; McGee, Donal; Mendrek, Barbara; Kowalczuk, Marek; et al. (MDPI, 2022-07-20)
      Poly-γ-glutamic acid (γ-PGA) is a bio-derived water-soluble, edible, non-immunogenic nylon-like polymer with the biochemical characteristics of a polypeptide. This Bacillus-derived material has great potential for a wide range of applications, from bioremediation to tunable drug delivery systems. In the context of oral care, γ-PGA holds great promise in enamel demineralisation prevention. The salivary protein statherin has previously been shown to protect tooth enamel from acid dissolution and act as a reservoir for free calcium ions within oral cavities. Its superb enamel-binding capacity is attributed to the L-glutamic acid residues of this 5380 Da protein. In this study, γ-PGA was successfully synthesised from Bacillus subtilis natto cultivated on supplemented algae media and standard commercial media. The polymers obtained were tested for their potential to inhibit demineralisation of hydroxyapatite (HAp) when exposed to caries simulating acidic conditions. Formulations presenting 0.1, 0.25, 0.5, 0.75, 1, 2, 3 and 4% (w/v) γ-PGA concentration were assessed to determine the optimal conditions. Our data suggests that both the concentration and the molar mass of the γ-PGA were significant in enamel protection (p = 0.028 and p < 0.01 respectively). Ion Selective Electrode, combined with Fourier Transform Infra-Red studies, were employed to quantify enamel protection capacity of γ-PGA. All concentrations tested showed an inhibitory effect on the dissolution rate of calcium ions from hydroxyapatite, with 1% (wt) and 2% (wt) concentrations being the most effective. The impact of the average molar mass (M) on enamel dissolution was also investigated by employing commercial 66 kDa, 166 kDa, 440 kDa and 520 kDa γ-PGA fractions. All γ-PGA solutions adhered to the surface of HAp with evidence that this remained after 60 min of continuous acidic challenge. Inductively Coupled Plasma analysis showed a significant abundance of calcium ions associated with γ-PGA, which suggests that this material could also act as a responsive calcium delivery system. We have concluded that all γ-PGA samples tested (commercial and algae derived) display enamel protection capacity regardless of their concentration or average molar mass. However, we believe that γ-PGA D/L ratios might affect the binding more than its molar mass.