bluuebunny/crossref_metadata_2025 huggingface dataset:
Dielectric spectroscopy and synergistic effects in epoxy composites filled with multi‐walled carbon nanotubes and carbon‐coated copper nanoparticles
Authors: Tsyhanok Dzmitry , Meisak Darya , Banys Juras , Macutkevič Jan , Selskis Algirdas , Sabalina Alisa , Platnieks Oskars , Gaidukovs Sergejs
Published: November 2024

The electromagnetic properties of epoxy‐based composites filled with carbon‐coated copper (Cu@C) nanoparticles and multi‐walled carbon nanotubes (MWCNTs), along with hybrid MWCNT/Cu@C/Epoxy systems containing varying concentrations of nanoinclusions, were systematically investigated across multiple frequency and temperature ranges. Measurements were conducted in the low‐frequency range (20 Hz–1 MHz) and over a temperature span of 40–500 K, as well as in the microwave frequency range (26–37 GHz) at room temperature. The percolation threshold was identified at approximately 2.5 vol% for composites containing only Cu@C nanoparticles and at 0.3 vol% for composites with MWCNTs. Notably, the hybrid MWCNT/Cu@C/Epoxy composites exhibited significantly enhanced electromagnetic properties compared to those of the single‐filled systems. At room temperature, an epoxy composite containing 5 vol% Cu@C and 1 vol% MWCNT exhibits a conductivity of approximately 4 × 10−2 S/m, which increases by nearly two orders of magnitude following a thermal cycle up to 500 K. The total electromagnetic interference (EMI) shielding effectiveness in the 26–37 GHz range was measured between 4 and 9 dB, indicating the material's promising potential for attenuating microwave noise. Dynamic mechanical analysis (DMA) results revealed that increasing the MWCNT content improved the storage modulus of the composites but led to a reduction in the glass transition temperature (Tg), which was observed to range between 40 and 50°C. The incorporation of MWCNTs and Cu@C nanoparticles into epoxy matrices offers a promising approach for the development of lightweight multifunctional composites with superior electrical, mechanical, and EMI shielding properties.

Highlights

The percolation threshold in MWCNT/Epoxy composites is 0.3%.

The percolation threshold in Cu@C/Epoxy composites is 2%.

The conductivity value of MWCNT/Cu@C/Epoxy composites is around 4 × 10−2 S/m.

The total shielding effectiveness in the Ka‐band range between 4 and 9 dB.

Glass transition temperature of MWCNT/Cu@C/Epoxy is between 40 and 50°C.
Experimental Analysis of Wire Drawing Influence on Microstructure, Texture, and Mechanical Properties of High‐Carbon Steel for Prestressing Strand
Authors: Meriem Meyssoune , Zidani Mosbah , Boutefnouchet Hafida , Ziouche Aicha , Abid Taher , Brisset François , Baudin Thierry , Proverbio Edoardo
Published: November 2024

The study aims to explore high‐carbon steel's behavior during cold drawing, focusing on the link between microstructural changes, texture, and mechanical properties at different strain levels. Using X‐ray diffraction, scanning electron microscopy–electron backscatter diffraction, micro‐ and nanoindentation, and wear analysis, findings show that grain size and interlamellar spacing decrease as strain increases, and pearlitic colonies become more compact and aligned. This refinement leads to significant hardening, from 333.8 HV in the wire rod to 470.4 HV at 2.05 strain, aligning with the Hall–Petch law. The <110> fiber texture develops linearly, and a higher dislocation density is noted at lower strain rates, with low‐angle grain boundaries increasing from 65.2% to 76.5%. The cold drawing process is thus divided into two phases, marked by a shift from low‐angle grain boundaries dominance and a notable reduction in wear rate compared to severely deformed states.
The collateral damage of rodenticide residues
Authors: Loeb Josh
Published: November 2024

With bird of prey poisoning – intentional or not – seemingly on the rise, Josh Loeb discusses a recent report from lobby group Wild Justice, which aims to quantify the impact of rodenticide residues on wildlife.
Message from the President
Authors: Mullineaux Liz
Published: November 2024

Liz Mullineaux encourages vets who are keen to be a voice for their profession to consider applying to be the next BVA Junior Vice President and then BVA President in 2026/27.
How writing an ‘Ask the vet’ column turned into a new career in public relations
Authors: Ellison Katy
Published: November 2024

Katy Ellison has used her love of writing to launch a career in communications while still maintaining her role as a practising veterinary surgeon.
Enhancing the properties and performance of ground nut shell biocomposites using compatibilizers and flame retardants
Authors: Guna Vijaykumar , Sheng Desmond Daniel Chin Vui , Mohan C. B. , Reddy Narendra
Published: November 2024

Composites developed from inexpensive, renewable, sustainable, and abundant bioresources such as groundnut shells (GNS) do not have the adequate properties required for commercial applications. Hence, most of the biocomposites developed from agricultural wastes or biomass are not used for practical applications. In this study, we have demonstrated that the addition of compatibilizers and flame‐resistant chemicals considerably enhances and makes the properties of GNS‐reinforced polypropylene (PP) composites suitable for commercial applications. One maleated polypropylene (MAPP) and two acrylic‐based compatibilizers (ABC1 and ABC2) were chosen and added into the composites in different proportions (1% to 5%). Ammonium polyphosphate (APP) was used to increase the flame retardancy of the composites. Ratio of reinforcement and matrix and composite forming conditions were also changed to achieve maximum benefits, and composites containing up to 80% GNS were developed. Tensile strength showed a good increase of 48%, whereas modulus showed a decrease of 35% with the addition of ABC2. However, the flexural strength and modulus of the composites increased with the addition of even 1% MAPP. The mechanical properties of the composites decreased when excess (5%) compatibilizer was used, probably due to agglomeration or an increase in incompatibility. Adding 3% of APP significantly improves both the flammability rating, LOI, and thermal properties. The highest flame resistance rating of V0 was obtained for both ratios, with the LOI increasing by about 40% and the conductivity decreasing marginally from 0.982 to 0.808 W/mK. Further, reduction in water absorption and hence increase in durability were also possible.

Highlights

GNS are major byproducts with limited use.

Composites made from GNS have poor mechanical and performance properties.

Addition of compatibilizers leads to substantial improvement in properties.

Excellent thermal and flame resistance is imparted by APP.

GNS composites are suitable for building, automotive, and other applications.
The State of Marriage in the Arab Mashreq: Jordan, Syria, Iraq, Palestine, and Lebanon
Authors: Jad Islah , Taminian Lucine , Mansour Rania , Rasheed Asmaa Jameel , Al Muaqat Fatima , Tarabay Maamoun
Published: November 2024

There is diverse literature on the Arab Mashreq, varying from analysis to readings of interdisciplinary political, social, and economic sciences (World Bank, Economic integration in the Mashreq. World Bank, Middle East and North Africa Region, 2010). In order to analyze the contextual reality and challenges of marriage in the Arab Mashreq, and despite the common infrastructure and societies of these countries, it is expected that each country is characterized by distinguishing fundamental differences, historically, socially, politically, economically, and culturally. In fact, many differences emerge between regions and provinces within the same country.
Influence of Diaphragms on Pressure and Heat Flux Measurements in a Shock Tunnel
Authors: Jang Byungkook , Kim Elliott Donghyun , Park Gisu
Published: November 2024

An experimental study investigated the flow disturbances caused by diaphragm debris in a shock tunnel, specifically between a driven tube and a nozzle. The impact of debris-induced disturbances on pressure and heat flux measurements was examined with two types of diaphragms: a single-layer ultra-thin polyethylene film and a double-layer diaphragm, where eight direction pre-cut polyethylene film was sealed with copper tape. The study involved measuring the pitot pressure and stagnation-point heat flux, using a flat-faced model and a hemisphere model, respectively. The pitot pressure was measured using a piezoelectric-based pressure transducer, while heat flux was recorded with a fast-response surface-junction coaxial thermocouple calibrated through the water-plunging method. The experimental data for both diaphragms correlated well with theoretical predictions. The shadowgraph flow visualization technique was employed to visualize diaphragm debris. The flow quality in the shock tunnel was assessed by analyzing normalized disturbances, representing fluctuations in pitot pressure, and heat flux measurements. The experimental results indicated that the double-layer diaphragm effectively reduced diaphragm debris and improved flow quality in shock tunnel experiments.
Genesis of artesian waters
Authors: Ivashchenko Pavlo M. , Yurchuk Olexander I.
Published: November 2024

Mankind has entered the era of fresh water scarcity. And the questions of the origin of these waters, as well as the methods of effective search for underground fresh water, become fundamental for the assessment of the prospects of water supply of the Earth's population not only in theoretical, but also in applied values. The article considers the volcanic-marine paradigm of artesian water genesis, which allows a logical explanation of a number of deep freshwater phenomena that cannot be resolved by other theories. The main consequences of the volcanic-marine paradigm are: (a) artesian water is recoverable, (b) deep freshwater resources are included in the water cycle in nature like groundwater, (c) the problem of extracting potable artesian water is not a resource problem for mankind, but a technological problem. At present, artesian water is searched for by drilling wells (direct method) and by geophysical methods of groundwater exploration—electrical survey, seismic survey and magnetic resonance method. At the same time, the great depth of artesian water, up to 1000 m, makes it difficult to locate it using geophysical methods. The article considers the geophysical method of direct detection of artesian water in various geological structures at great depths. This method and the service based on it have been named “Geodirect RSS/NMR”. Their physical basis is the resonance between the pre-recorded spectrum of the sought substance (in our case, artesian water) and the spectrum of radiations recorded by the satellite instrumentation in the infrared range. The presence of resonance allows direct identification of artesian water flows and reservoirs without interpretation of indirect data.
Building Quantum Computers
Authors: Majidy Shayan , Wilson Christopher , Laflamme Raymond
Published: November 2024

The global race to build the world's first quantum computer has attracted enormous investment from government and industry, and it attracts a growing pool of talent. As with many cutting-edge technologies, the optimal implementation is not yet settled. This important textbook describes four of the most advanced platforms for quantum computing: nuclear magnetic resonance, quantum optics, trapped ions, and superconducting systems. The fundamental physical concepts underpinning the practical implementation of quantum computing are reviewed, followed by a balanced analysis of the strengths and weaknesses inherent to each type of hardware. The text includes more than 80 carefully designed exercises with worked solutions available to instructors, applied problems from key scenarios, and suggestions for further reading, facilitating a practical and expansive learning experience. Suitable for senior undergraduate and graduate students in physics, engineering, and computer science, Building Quantum Computers is an invaluable resource for this emerging field.
Textile and food waste biodegradation for the production of composite mycelium materials using Pleurotus ostreatus
Authors: Sangosanya Annah-Ololade , Pistofidou Anastasia
Published: November 2024

The fashion industry produces over 100 billion garments per year, of which 85% end up in landfill before the end of the year. Considering filamentous fungi are capable of biodegrading cellulose and complex molecules and of producing a wide range of biomaterials, an opportunity to rethink the linearity of the textile industry emerges. Biodegradation of various combinations of denim textile waste, synthetic textile waste, food waste and spent coffee grounds were investigated using Pleurotus ostreatus mycelium. The resulting composite material was tested for its use in material production. The outcomes of the study showed that Pleurotus ostreatus mycelium could successfully grow on all the combinations of food waste (vegetable peels and coffee grounds) with textile waste (synthetic textile and denim textile), and even on denim textile waste only. Provided the soft nature of the substrate, the textile and food waste mycelium composite is also malleable, and therefore interesting for applications in the textile industry. A protocol for post processing of the flexible composite material using low energy and natural components (heat, water, glycerol, and wax) was created to transform the composite into a leather-like fungal material.
Cascading employment as paradigmatic form of precarious work: The case of IT agency workers in the United States
Authors: Liang Xiaochen
Published: November 2024

Cascading employment is an increasingly prevalent yet understudied form of employment arrangement, where an employer places a worker in a client’s workplace through a sequence of labour intermediaries, with no direct contractual relationship between the worker’s employer and the end client. In this article, cascading employment is conceptualised as a distinct and normalised form of precarious work and differs from ‘triangular employment’ in several dimensions. The study reported herein draws on interviews with U.S.-based IT workers and stakeholders engaged in cascading employment. Findings reveal three key dimensions of cascading employment: multilayeredness, hierarchical fissuring, and relationship heterogeneity. These dimensions contribute to the aspects of precariousness of employment, including diluted income, heightened employment uncertainty, reduced worker control over working conditions, and limited legal protections. Moreover, the precariousness of cascading employment stems from the complexity of the employment arrangements, not merely from factors such as contract type, employment status, and industry, which are typical in explaining precariousness. Therefore, ‘complexity of employment arrangements’ should be recognised as a crucial criterion for employment precariousness. ‘Complexity’ can be measured by the number of actors involved, the extent of fissuring in employer costs and responsibilities, and the variety and intensity of inter-actor relationships.
“Gut” to grips with the science of the microbiome – a symposium report
Authors: Finnegan Yvonne E. , Neill Holly R. , Prpa Emily J. , Pot Bruno
Published: November 2024

The latest Yakult Science Study Day was held virtually on 2 November 2023. Aimed at healthcare professionals, researchers, and students, a variety of experts explored the latest gut microbiome research and what it means in practice. The morning sessions discussed the role of the microbiome in health and disease, the rapid advancements in DNA sequencing and implications for personalised nutrition, the current state of evidence on health benefits associated with fermented foods, prebiotics and probiotics and the challenges involved in interpreting research in this area. The afternoon session considered the emerging research on the microbiota–gut–brain axis in mediating effects of food on mood, the bidirectional impact of menopause on the gut microbiota, and the interplay between the gut and skin with implications for the treatment of rare and common skin disorders. The session ended with an update on the use of faecal microbiota transplant in both research and clinical practice. Undoubtedly, the gut microbiome is emerging as a key conductor of human health, both in relation to gastrointestinal and non-gastrointestinal outcomes. As research continues to elucidate mechanisms of action and confirm their effects in human trials, the gut microbiome should be a key consideration within a holistic approach to health moving forward.
Campana, the ‘End of Art’, and Hegel’s Philosophy of Literature
Authors: Liu Chunge
Published: November 2024

Based on Hegel’s thesis of the ‘end of art’, this paper aims to explore how to study Hegel’s philosophy of literature by carrying out a dialogue with Francesco Campana. In his recent book, The End of Literature, Hegel, and the Contemporary Novel (2019), Campana demonstrates how literature resists its end by continuous self-transformation and provides a framework of ‘philosophization’–‘poetry’–‘ordinariness’ in understanding the contemporary novel. While, to some extent, I agree with him on the understanding of the ‘end of art’ thesis, I object to his idea that ‘philosophization’ and ‘ordinariness’ are two poles between which poetry moves. I defend the view that, from the perspective of Hegel’s absolute and taking Hegel’s philosophy as a totality, ‘philosophization’ and ‘ordinariness’ are inseparable. Furthermore, I emphasize the significance of Hegel’s thesis of the ‘end of art’, which I argue lies in revealing the problem of modern subjectivity. Literature, as a unique form of art, also reveals this problem and helps to solve it. Therefore, in the study of Hegel’s philosophy of literature, I insist on adopting the perspective of Hegel’s absolute and taking Hegel’s philosophy as a whole so that we can build connections among different disciplines and among different art-forms and art-types. With this perspective, I make some proposals, which include several paradigms for the study of Hegel’s philosophy of literature. Finally, in terms of the thesis of the ‘end of art’, I maintain that the study of Hegel’s philosophy of literature is to address the problem of modern subjectivity.
Detrital U-Pb ages for the first well-preserved vascular plant Cooksonia from the UK and Irish macrofossil record.
Authors: Garza Hector K , Catlos Elizabeth J , Brookfield Michael E , Malkowski Matthew A , Chamberlain Kevin R , Loewy Staci L , Stockli Daniel F
Published: November 2024

The emergence of vascular plants, such as Cooksonia, had a profound impact on Earth’s Early Paleozoic biogeochemical cycles (e.g. atmospheric oxygen, nitrogen and CO2), potentially triggering global environmental and biological changes. However, the timing of Cooksonia’s terrestrial emergence remains elusive as phylogenetic models, microfossils and macrofossils provide different timings for land colonization by vascular plants. Here, hundreds of zircon grains from three siltstones were dated using Laser Ablation-Inductively Couple Plasma-Mass Spectrometry (LA-ICP-MS). The study presents detrital zircon U-Pb dates, which refine the current biostratigraphy ages assigned to Cooksonia macrofossils from the three oldest sites globally. Specifically, siltstones hosting Cooksonia macrofossils from Borrisnoe Mountain (Ireland) and Capel Horeb (Wales) yield Gorstian–Homerian maximum depositional ages (MDAs) of 426 ± 2 Ma and 427 ± 2 Ma, respectively. Additionally, Cwm Graig Ddu (Wales) yields a (Pridoli-Ludlow) maximum age of 423 ± 3 Ma. The findings provide the first detrital zircon U-Pb dates for the oldest Cooksonia macrofossils globally and contribute crucial maximum ages. These maximum ages are instrumental in refining future calibrations of molecular clocks and improving phylogenetic models, thus contributing significantly to a better understanding of Cooksonia’s evolutionary history, including its environmental and ecological impacts.
Being and Doing Together in a Naturally Occurring Retirement Community: Pandemic Experiences of Older Adults
Authors: Fernandes Kassandra , Hand Carri , Laliberte Rudman Debbie , McGrath Colleen , Cooper Helen C. , Donnelly Catherine , DePaul Vincent G. , Letts Lori , Richardson Julie
Published: November 2024

Developing effective, sustainable strategies that promote social inclusion, reduce isolation, and support older adults’ wellbeing continues to be important to aging communities in Canada. One strategy that targets community-living older adults involves identifying naturally occurring retirement communities (NORCs) and supporting them through supportive service programs (NORC-SSPs). This qualitative descriptive study utilized semi-structured interviews to explore how older adults living in a NORC supported by an SSP, sought to build, and maintain, a sense of community during the COVID-19 pandemic. Analysis revealed how changes in context prompted changes in the program and community, and how despite lack of in-person opportunities participants continued to be together and do occupations together in creative ways that supported their sense of community. NORC-SSPs, like Oasis, play an important role in supporting older adults’ capacity to build strong, resilient communities that support wellbeing, during a global pandemic and in non-pandemic times.
In sight on olive oil maceration and supercritical CO2 in extracting rosemary essential oil
Authors: Soltan Maha Mohamed , Mahfouz Sabry , Motawe Fatma H. , Karam Eman A. , El-Hagrassi Ali
Published: November 2024

The flavor, nutritional, and medicinal value of rosemary are well known. Hydrodistilled (HD) essential oil was prepared in the present study as a standard. Olive oil maceration (OM) and supercritical carbon dioxide (SC-CO2) technology were separately applied to extract the essential oil of rosemary. The three obtained products, HD, OM, and SC-CO2, were compared concerning their main constituents using GC‒MS. Their antimicrobial properties were evaluated against eight microbes by the disc diffusion assay. Interestingly, both 1,8-cineol and camphor were the major compounds in the three oils. α-Pinene was also detected in large amounts in both HD and OM. Additionally, borneol was the third major component in SC-CO2. The antimicrobial results revealed differential effects against six microbes. However, HD oil also exhibited antifungal activity. Maceration is a green extraction procedure that is easy to perform in households, and attention must be paid to olive oil maceration as a complementary medicine that originated in pharaohs.
In-situ synthesis and integration of gold nanoparticles into 3D printed optical fiber probes
Authors: Chekkaramkodi Dileep , Turk Said El , Ali Murad , Butt Haider
Published: November 2024

This work uses the polymeric reduction method to explore the in-situ synthesis of gold nanoparticles (AuNPs) within 3D-printed optical fiber probes (OFPs). Digital light processing (DLP) 3D printing is employed to fabricate the OFPs using a resin consisting of hydroxyethyl methacrylate (HEMA) and polyethylene glycol diacrylate (PEGDA). After printing, OFPs were immersed in a boiling gold precursor solution to facilitate the synthesis of AuNPs inside the polymer matrix. We produced single material (HEMA/PEGDA) and multimaterial (HEMA/PEGDA + Dentaclear) OFPs loaded with AuNPs at different concentrations. Scanning electron microscopy analysis confirmed the effective distribution and dispersion of AuNPs within the polymer matrix. The optical properties, including reflection and transmission spectra, are comprehensively measured using customized setups. The localized surface plasmon resonance of the embedded AuNPs created a distinct dip in the 500–600 nm wavelength range. Higher AuNP concentrations and longer dipping times enhanced light absorption, reducing reflection and transmission intensities. Multimaterial OFPs also exhibited tunable wavelength filtering capabilities based on the AuNP concentration. The AuNP-loaded OFPs demonstrated stable optical performance across varying temperatures and pH environments, highlighting their potential for diverse applications.
Applications of Marine Resources for Generation of Green Energy: A Step Towards Attaining Sustainable Development
Authors: Rimon Shah Tanvir Alam , Hossain Gazi Arman , Kibria Md. Golam , Sarker Md. Rabiul Islam , Mourshed Monjur
Published: November 2024

The shift to renewable energy sources has become essential in light of growing concerns in climate change and environmental deterioration. This chapter examines the use of marine resources to produce green energy as a crucial step toward both economic expansion and sustainable development. With a wide range of technologies including tidal, wave, offshore wind, solar, and marine biomass that may tap into the enormous energy reserves of the oceans and seas, marine-based renewable energy has enormous promise. By offering a dependable and low-carbon substitute for fossil fuels, marine-based renewable energy (MRE) sources reduce greenhouse gas (GHG) emissions and their negative environmental effects. Furthermore, advancing marine-based renewable energy provides a chance to promote innovation, jobs, and economic prosperity. By analyzing policy frameworks, case studies, and technological advancements, this chapter advocates for the widespread adoption of marine-based renewable energy as a catalyst for a more prosperous and environmentally sustainable future.
Regulatory Effect of PDGF/PDGFR on Hematopoiesis
Authors: Liu Yong , Huang Junbin , Li Lindi , Duan Yifei , Chong Beng H. , Li Liang , Yang Mo
Published: November 2024

Platelet-derived growth factor (PDGF) is a critical cytokine with substantial regulatory effects on hematopoiesis. Recent research highlights the essential role of PDGF in the modulation of hematopoietic stem/progenitor cells (HSPCs), megakaryocytes/platelets, and thrombopoietin (TPO) synthesis within the bone marrow microenvironment. PDGF directly stimulates the proliferation and differentiation of HSPCs while also inhibiting apoptosis. In addition, PDGF indirectly enhances the production of other growth factors, including granulocyte–macrophage colony-stimulating factors. Further, PDGF regulates TPO production and influences the bone marrow milieu, thus impacting hematopoiesis and platelet formation. Mechanistically, PDGF binds to its receptor, PDGF receptor (PDGFR), thus activating the PDGF/PDGFR signaling pathway. This pathway subsequently activates phosphoinositide 3-kinase/protein kinase B, leading to the activation of downstream cytokines, including c-Fos and NF-E2, while inhibiting caspase-3 activation. Collectively, these actions have prodifferentiation and antiapoptotic effects on megakaryocytes, thereby regulating platelet production. This review provides a comprehensive analysis of the regulatory role of the PDGF/PDGFR axis in hematopoiesis, with a particular focus on platelet production, by summarizing all studies on PDGF/PDGFR from our group and globally.
Double-peak structure in Nb–I–Pb tunnel junctions
Authors: Belous N. A. , Lezhnenko I. V. , Pan V. M. , Rudenko É. M.
Published: November 2024

We studied Nb–I–Pb thin-film tunnel junctions whose bias dependence of the differential resistance has a double-peak structure. It is assumed that, besides regions of pure material with a high critical temperature and regions of normal metal, regions with a relatively low (≈5.5°K) critical temperature exist in the vicinity of the barrier of the niobiuim thin film. The properties of the low-Tc regions are, to a large extent, determined by proximity effects. The results are treated within the framework of the tunnel model of the proximity effect.
Magnetoresistance of whiskers of Bi1–xSbx(O<x ≤0.2) alloys in strong longitudinal fields
Authors: Gitsu D. V. , Dolma V. A. , Muntyanu F. M.
Published: November 2024

The magnetoresistivity Δρ‖(B)/ρ(0) of thin whiskers (0.5 μ≤d≤14 μ) of Bi1–xSbx(0<x ≤0.2) alloys was studied in longitudinal (B‖I‖C2) de magnetic fields of up to 15 T at helium temperatures. A large negative magnetoresistivity (∽90%) was detected and it was established that in extremely strong magnetic fields the Δρd||(B)/ρ(0) in whiskers with d ≳ 1 μ and the Δρ∞||(B)/ρ(0) in bulk specimens are comparable in magnitude.
Reassessment of the dipole in the distribution of quasars on the sky
Authors: Abghari Arefe , Bunn Emory F. , Hergt Lukas T. , Li Boris , Scott Douglas , Sullivan Raelyn M. , Wei Dingchen
Published: November 2024

We investigate recent claims by Secrest et al. of an anomalously large amplitude of the dipole in the distribution of CatWISE-selected quasars on the sky. Two main issues indicate that the systematic uncertainties in the derived quasar-density dipole are underestimated. Firstly, the spatial distribution of the quasars is not a pure dipole, possessing low-order multipoles of comparable size to the dipole. These multipoles are unexpected and presumably caused by unknown systematic effects; we cannot be confident that the dipole amplitude is not also affected by the same systematics until the origin of these fluctuations is understood. Secondly, the 50 percent sky cut associated with the quasar catalogue strongly couples the multipoles, meaning that the power estimate at ℓ = 1 contains significant contributions from ℓ > 1. In particular, the dominant quadrupole mode in the Galactic mask strongly couples the dipole with the octupole, leading to a large uncertainty in the dipole amplitude. Together these issues mean that the dipole in the quasar catalogue has an uncertainty large enough that consistency with the cosmic microwave background (CMB) dipole cannot be ruled out. More generally, current data sets are insufficiently clean to robustly measure the quasar dipole and future studies will require samples that are larger (preferably covering more of the sky) and free of systematic effects to make strong claims regarding their consistency with the CMB dipole.
Revisiting flame spread: new problems, new tools, new opportunities
Authors: Hadden Rory M.
Published: November 2024

Flame spread underpins a huge range of fire problems and encompasses some of the most complex aspects of fire science especially a strong coupling between gas and solid phase phenomena. Although there are many approaches to predict or model flame spread behaviour, many of these rely on empirical data and cannot be used in a predictive capacity. However, these models date from a time when the objectives of fire science were different from today with a strong emphasis on developing standardised testing methods and providing information to first responders. Advances in diagnostics and modelling in recent years along with changes in the needs of users of fire safety science means that there are significant new opportunities, and benefits, to enhancing our understanding of flame spread. These will be explored with emphasis given to furthering understanding of the fundamental processes underpinning flame spread, the challenges of the applications of flame spread and the tools that we might be able to adopt to answer these questions.
Methodology for the determination of the thermo-physical properties of densified wood over thermal decomposition
Authors: Bellamy G T , McKinnon M B
Published: November 2024

The increased prevalence of timber construction and desire for increased fire resistance has prompted the need for novel materials, such as densified wood, to meet this growing need. In this study, a method is outlined for the determination of the thermo-physical properties of densified wood and related materials which spans the full range of temperatures experienced in typical fire scenarios. The assessment of the thermal stability and specific heat capacity of the material indicates a decomposition pattern typical for biomass and a heat capacity that is resolved as a function of both the instantaneous temperature and the maximum pyrolysis temperatures to which the material has been exposed. Coupling these data with dilatometry allows determination of all intermediate real- and pseudo-component densities which may be implemented into a computational fire model. The use of light flash analysis presents a method for direct determination of thermal conductivity of the densified wood and its char at relevant temperatures using results derived from the other instruments. The thermal conductivity of the char was found to be notably dependent on the maximum pyrolysis temperature and non-revertible, despite the lack of mass loss in this region, indicating morphological changes in the solid may be responsible.
Intermediate scale testing for ORS
Authors: Åström Joakim , Nilsson Marin , Van Hees Patrick
Published: November 2024

In order to design an Oxygen Reduction System (ORS) the most important parameter is the limiting oxygen concentration (LOC). Currently there are a couple of different small scale test methods used to determine the LOC for specific materials. In small scale tests an external heat flux is applied, to account for parameters such as geometry that otherwise cannot be replicated, theoretically arriving at a sufficiently low LOC. Other methods have tried to take heat transfer and geometry into consideration to better replicate real world conditions. However, there are some discussions into the validity to some of these existing methods. To replicate real world conditions a large scale setup was designed and used to determine LOC for certain warehouse configurations. This large scale setup is costly to run and therefore there is a need to investigate the possibility of creating an intermediate scale setup that has the ability to make flame propagation assessments for varying fuels, geometries and ignition sources. In this paper a first attempt for an intermediate scale setup is examined, and preliminary findings are discussed.
Thermal conditions within the solid during opposed flow flame spread under a forced flow
Authors: Morrisset David , Hadden Rory M. , Law Angus
Published: November 2024

Previous studies have identified a transition between a thermally driven and a kinetically driven regime for opposed flow flame spread. Identifying this transition has been traditionally achieved through the use of a Damköhler number (Da). While an elegant approximation, this characterization lacks an explicit link to the solid phase (e.g., thermal conditions in the solid) when describing the thermal and gas phase regimes. Experiments were conducted under forced flow conditions (0-1.5 m/s) to quantify the thermal conditions ahead of the flame front in PMMA for a range of conditions. Defining the thermal conditions in the solid provides a more explicit characterization of the competing thermal and gas-phase effects on the measured flame spread rate than relying on the (Da) alone; therefore providing a more explicit link between solid and gas-phase processes. Higher temperatures throughout the solid were observed at high flow rates, suggesting increased heat transfer through the solid. However, at these high flow rates, the flame spread rate was found to decrease, suggesting increasing effects of the reaction rate on the flame spread rate. Temperature measurements were also paired with a simple pyrolysis model to comment on the influence of both mixing and the reaction rate of the flame on the rate of spread.
Investigating the flammability of metal composite panels
Authors: MacLeod C E , Butterworth N , Law A
Published: November 2024

Metal composite panels have been introduced into the built environment over the last 50 years, to combine weatherproofing, rigidity, energy efficiency, and aesthetics. However, the use of these composite panels has been brought about without a full understanding of their relevant fire hazards. This has been brought into the immediate attention due to the events of the Grenfell tower fire. The flammability and heat transfer behaviours of these panels need to be better understood in order to both better understand previous events, and potential future hazards. Experiments performed in the cone calorimeter have shown that the ignition and flammability parameters are controlled by a hierarchy of dominant heat transfer mechanisms. Local, where polymer layers are thick enough to not be significantly affected by the metal skins. Product, where the layers are acting as one bulk product, and are affected by the heat transfer through the depth. System, where system effects (i.e. thermal boundary conditions) affects the heat flow out from the product. This work shows that fire behaviour is typically dominated by either Local or System effects – with Product level behaviours playing a relatively minor role.
AI-Based Material Parameter Prediction from Cone Calorimeter Measurements
Authors: Punnoli Valayanad Swathikrishna , Arnold Lukas
Published: November 2024

In pyrolysis simulation, methods such as inverse modelling are used to determine the material parameters from small-scale experiments. This often requires significant computational resources due to its iterative nature. This study investigates an artificial intelligence (AI)-based alternative approach, that can give instantaneous predictions for material parameters once trained. A dataset based on Fire Dynamics Simulator (FDS) simulation of a cone calorimeter experiment is used for training these AI models. Different AI models are trained to predict polymethyl methacrylate’s thermo-physical parameters using heat release rate (HRR) curves as input. AI models including Random Forest, 1D-convolution, and Recurrent Neural Networks showed the ability to predict the material parameters accurately with low mean squared error on the test dataset. These models were also able to recreate the HRR curves in FDS using their predictions, following the trend of the experimental HRR curve closely. Expanding the dataset to include materials with different behaviours and modelling different experiments could give these AI models broader applicability. However, FDS version dependence is a limitation for the AI models explored here because they were trained on a simulation-based dataset. Looking at the results, AI models in general can be used to predict material parameters required for pyrolysis modelling, potentially saving time and effort or, at the very least, used to complement the existing inverse modelling approaches.
Fire protection of nuclear waste: evaluation at reduced scale
Authors: Bourbigot Serge , Sanusi Olawale , Bachelet Pierre , Fontaine Gaëlle , Lemperière François
Published: November 2024

Concrete containers are commonly used for storing and transporting nuclear waste. However, metals like aluminum cannot be directly conditioned in concrete due to their rapid and exothermic reactions with the alkalis present in the concrete. To address this issue, Orano DS investigates the use of Matrix Mortar of Resin (MMR), which embeds metal waste within a resin matrix (e.g. epoxy resin). The protective MMR is then stored in concrete containers. The French agency ANDRA oversees radioactive waste management and developed its own standards such as ET060, which evaluates fire behavior in waste packages. A bench-scale fire test mimicking ET060 was successfully developed in this work. Small containers were made to fit within the test and were instrumented with thermocouples. It was evidenced that the MMR was not degraded during the test (protection by the concrete shell) and that the conditions of the test were fulfilled.
Optimization of Flame Retardant Polypropylene via Machine Learning
Authors: Verret Eric , Collin Anthony , Duquesne Sophie
Published: November 2024

In this study, we explore the application of Multi-Objective Bayesian Optimization (MOBO), a machine learning-based method, for the development of flame-retardant polypropylene (PP) formulations. This approach leverages the power of Gaussian Processes (GPs) to accurately model the behavior in the Limiting Oxygen Index (LOI) flame test and uses the qNEHVI acquisition function for efficient design space exploration. We focus on a bi-objective optimization strategy, aiming to maximize LOI values while minimizing the content of flame retardant (FR) additives. Our research successfully navigates the complexities of optimizing material properties by proposing an optimal formulation within a constrained evaluation framework, comprising five iterations of three parallel evaluations with a total budget of 20 points. This work highlights MOBO’s potential as a transformative tool for advanced materials science, particularly in achieving high-performance flame-retardant materials.
Effect of Thermal Radiation in Porous Structures and Thermophysical Properties Variations in PVC Pyrolysis modelling: A Study Using Optimization Techniques.
Authors: Abdelhafiz Y , Amokrane A , Debenest G , Bourbigot S
Published: November 2024

In this study, numerical simulations are performed using the Gpyro software to model the thermal decomposition of PVC filled with CaCO3 (FPVC) during a cone calorimeter experiment. For its kinetic behaviour, data are provided through TGA measurement, while the most important thermophysical properties in the virgin state before decomposition are obtained from dedicated measurements. Regarding the properties during the decomposition process, as no data is available, hypotheses are formulated and challenged: do the properties remain constant during decomposition or not? Additionally, a particular focus is placed on the consideration of thermal radiation within the pores. The ability of these two different hypotheses to reproduce the experimental behaviour is explored through inverse simulation. The radiative phenomenon is validated on additional experiments dedicated to the measurement of conductivity with temperature, as well as pores size measurement. The findings emphasize the indispensable role of incorporating radiative contributions within pores. Furthermore, by accounting for changes in thermophysical properties during decomposition, the simulations accuracy is enhanced.
Identifying the different processes occurring during the steady state charring of solids
Authors: Reep J , Torero J L , Spearpoint M , Hadden R M
Published: November 2024

A revised means of controlling the Fire Propagation Apparatus (FPA), enabling a constant mass loss rate (MLR), was used to assess effluent generated during the steady state pyrolysis and subsequent charring of polyisocyanurate (PIR) and phenolic insulation foams. The MLR for each foam was set (1 g s−1 m−2), with char formation being investigated under three differing oxidative environments (0, 10 and 20.9 % O2). The transition from pyrolysis into char formation was identified by the increased heat flux supplied by the FPA lamps whilst maintaining the constant MLR. Species detected in the effluent were found to be both material and process specific; hydrogen cyanide (HCN) was prominent in PIR effluent, whilst phenolic foam tended to favour carbon monoxide (CO) generation. Obtained yields of CO and HCN showed good correlation with the wide range of steady state tube furnace literature data, with an increase in the CO yield aligning with the observation of char formation. It is shown that the oxidative environment can impact the transition between differing combustion processes, thus care must be taken when generating representative effluent streams for emission sampling.
Representative elementary volume combustion calorimetry (RevCC): a bench-scale apparatus for measuring heat release rate & total heat release of composites
Authors: Ha K , Tranchard P , Bachelet P , Ramgobin A , Augé M-O , Cavalli P , Bourbigot S
Published: November 2024

The Microscale Combustion Calorimeter (MCC) is commonly utilized to assess the fire behaviour of polymers at the microscale. However, for highly heterogeneous composite materials, such as sandwich laminates commonly found in aircraft interiors, obtaining a representative sample in few milligrams is impossible. In this work, we developed the Representative Elementary Volume Combustion Calorimeter (RevCC), a mesoscale testing platform inspired by the MCC principle, to characterize the fire behaviour of our highly heterogeneous laminated materials. A comparison of results obtained from complex materials using both devices reveals that scaling influences the behavior of sandwich materials when subjected to high temperatures.
Large eddy simulations of weakly turbulent diffusion flames in a co-flow with reduced oxygen concentration
Authors: Moorthamers Y. , Snegirev A. , Maragkos G. , At Thabari J. , Merci B.
Published: November 2024

A novel sub-grid combustion model (SCM) recently proposed for weakly turbulent buoyant diffusion flames is applied to simulate 10 and 15 kW ethylene-fueled flames produced by a circular porous burner in the oxidizer co-flow with normal and reduced oxygen concentrations. The computational approach enables modeling soot production and radiative emission based on local resolved specie concentrations and temperature, thereby avoiding prescription of the soot yield and global radiative fraction as is conventional in engineering fire simulations. For oxygen mole fraction of 0.21 in the oxidizer co-flow, good agreement between the predicted and the measured spatial distributions of mean temperatures and soot volume fractions has been demonstrated, while considerable deviation is observed for the velocity profiles in the vicinity of the burner. At any oxygen concentration, the experimental combustion efficiency and radiative fraction are reasonably replicated by the simulations, and the limiting oxygen concentration causing complete flame extinguishment is predicted well by the SCM.
Towards predictive engineering-type simulations of upward flame spread in SBI scenarios
Authors: Maragkos Georgios , Snegirev Alexander , At Thabari Jeri , Moorthamers Youk , Merci Bart
Published: November 2024

Focusing on advancing predictive modelling of upward flame spread using CFD, large eddy simulations using FireFOAM are presented. A fully dynamic approach with respect to turbulence, combustion and radiation, as well as modelling convective heat transfer based on Newton’s law with simplified correlations for natural convection, is considered. The thermal decomposition of the solid material is modelled using a 1D pyrolysis model combined with optimised model-effective material properties. For validation purposes, a series of medium-scale Single Burning Item (SBI) experiments using both inert (calcium silicate) and flammable walls (plywood) is considered. Separate validation of the gas (pool fires) and solid (anaerobic pyrolysis) phases is also reported. A comprehensive comparison between the CFD model predictions and available experimental data is performed. The modelling approach performs very satisfactorily with the predictions being rather grid-insensitive and resulting in maximum deviations in the predicted HRR, between the coarsest and finest grid size, on the order of 15%.
A novel combustion model based on the fast chemistry assumption for the simulation of turbulent buoyant flames
Authors: Motaghian Shahrooz , Beji Tarek
Published: November 2024

In this paper, a combustion model based on the fast chemistry assumption is proposed for the large eddy simulation (LES) of turbulent buoyant flames. Transport and chemistry are decoupled. Contrary to commonly applied models, the proposed approach does neither rely on a constant nor the cell size and ignores sub-grid scale mixing. In order to assess the proposed model, a 37 cm methane flame is simulated and the EDM model is considered as the reference model. The results indicate that the new model is capable of predicting the average temperature and velocity on the burner’s centerline reasonably accurately. The comparison between the reference and the proposed models reveals that the EDM model requires recalibration for the coarser grid because it is cell size-dependent. Contrarily, the proposed model shows lower grid sensitivity and no need for recalibration. In general, the proposed model is more reliable in problems where the appropriate constant for EDM is unknown.