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Chung E, Ren G, Johnston I, Matharu RK, Ciric L, Walecka A, Cheong YK. Applied Methods to Assess the Antimicrobial Activity of Metallic-Based Nanoparticles. Bioengineering (Basel) 2023; 10:1259. [PMID: 38002383 PMCID: PMC10669044 DOI: 10.3390/bioengineering10111259] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2023] [Accepted: 10/24/2023] [Indexed: 11/26/2023] Open
Abstract
With the rise of antibiotic resistance, the drive to discover novel antimicrobial substances and standard testing methods with the aim of controlling transmissive diseases are substantially high. In healthcare sectors and industries, although methods for testing antibiotics and other aqueous-based reagents are well established, methods for testing nanomaterials, non-polar and other particle-based suspensions are still debatable. Hence, utilities of ISO standard validations of such substances have been recalled where corrective actions had to be taken. This paper reports a serial analysis obtained from testing the antimicrobial activities of 10 metallic-based nanomaterials against 10 different pathogens using five different in vitro assays, where the technique, limitation and robustness of each method were evaluated. To confirm antimicrobial activities of metallic-based nanomaterial suspensions, it was found that at least two methods must be used, one being the agar well diffusion method, which was found to be the most reliable method. The agar well diffusion method provided not only information on antimicrobial efficacy through the size of the inhibitory zones, but it also identified antimicrobial ions and synergistic effects released by the test materials. To ascertain the effective inhibitory concentration of nanoparticles, the resazurin broth dilution method is recommended, as MIC can be determined visually without utilising any equipment. This method also overcomes the limit of detection (LoD) and absorbance interference issues, which are often found in the overexpression of cell debris and nanoparticles or quantum dots with optical profiles. In this study, bimetallic AgCu was found to be the most effective antimicrobial nanoparticle tested against across the bacterial (MIC 7 µg/mL) and fungal (MIC 62.5 µg/mL) species.
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Affiliation(s)
- Etelka Chung
- Centre for Engineering Research, University of Hertfordshire, Hatfield AL10 9AB, UK; (E.C.); (I.J.)
| | - Guogang Ren
- Centre for Engineering Research, University of Hertfordshire, Hatfield AL10 9AB, UK; (E.C.); (I.J.)
| | - Ian Johnston
- Centre for Engineering Research, University of Hertfordshire, Hatfield AL10 9AB, UK; (E.C.); (I.J.)
| | - Rupy Kaur Matharu
- Department of Mechanical Engineering, University College London, Torrington Place, London WC1E 7JE, UK;
- Department of Civil, Environmental and Geomatic Engineering, University College London, Gower Street, London WC1E 6BT, UK;
| | - Lena Ciric
- Department of Civil, Environmental and Geomatic Engineering, University College London, Gower Street, London WC1E 6BT, UK;
| | - Agnieszka Walecka
- Intensive Care Unit, Royal Free Hospital, Royal Free London NHS Foundation Trust, Pond Street, London NW3 2QG, UK;
| | - Yuen-Ki Cheong
- Centre for Engineering Research, University of Hertfordshire, Hatfield AL10 9AB, UK; (E.C.); (I.J.)
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Matharu RK, Ahmed J, Seo J, Karu K, Golshan MA, Edirisinghe M, Ciric L. Antibacterial Properties of Honey Nanocomposite Fibrous Meshes. Polymers (Basel) 2022; 14:polym14235155. [PMID: 36501550 PMCID: PMC9740266 DOI: 10.3390/polym14235155] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2022] [Revised: 10/25/2022] [Accepted: 11/21/2022] [Indexed: 11/30/2022] Open
Abstract
Natural substances are increasingly being developed for use in health-related applications. Honey has attracted significant interest, not only for its physical and chemical properties, but also for its antibacterial activity. For the first time, suspensions of Black Forest honeydew honey and manuka honey UMF 20+ were examined for their antibacterial properties against Escherichia coli and Staphylococcus epidermidis using flow cytometry. The inhibitory effect of honey on bacterial growth was evident at concentrations of 10, 20 and 30 v/v%. The minimum inhibitory effects of both honey types against each bacterium were also investigated and reported. Electrospray ionisation (ESI) mass spectrometry was performed on both Black Forest honeydew honey and manuka honey UMF 20+. Manuka honey had a gluconic concentration of 2519 mg/kg, whilst Black Forest honeydew honey had a concentration of 2195 mg/kg. Manuka honey demonstrated the strongest potency when compared to Black Forest honeydew honey; therefore, it was incorporated into nanofiber scaffolds using pressurised gyration and 10, 20 and 30 v/v% manuka honey-polycaprolactone solutions. Composite fibres were analysed for their morphology and topography using scanning electron microscopy. The average fibre diameter of the manuka honey-polycaprolactone scaffolds was found to range from 437 to 815 nm. The antibacterial activity of the 30 v/v% scaffolds was studied using S. epidermidis. Strong antibacterial activity was observed with a bacterial reduction rate of over 90%. The results show that honey composite fibres formed using pressurised gyration can be considered a natural therapeutic agent for various medicinal purposes, including wound-healing applications.
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Affiliation(s)
- Rupy Kaur Matharu
- Department of Mechanical Engineering, University College London, Torrington Place, London WC1E 7JE, UK
- Department of Civil, Environmental & Geomatic Engineering, University College London, Chadwick Building, Gower Street, London WC1E 6BT, UK
- Correspondence:
| | - Jubair Ahmed
- Department of Mechanical Engineering, University College London, Torrington Place, London WC1E 7JE, UK
| | - Jegak Seo
- Department of Civil, Environmental & Geomatic Engineering, University College London, Chadwick Building, Gower Street, London WC1E 6BT, UK
| | - Kersti Karu
- Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, UK
| | - Mitra Ashrafi Golshan
- Department of Civil, Environmental & Geomatic Engineering, University College London, Chadwick Building, Gower Street, London WC1E 6BT, UK
| | - Mohan Edirisinghe
- Department of Mechanical Engineering, University College London, Torrington Place, London WC1E 7JE, UK
| | - Lena Ciric
- Department of Civil, Environmental & Geomatic Engineering, University College London, Chadwick Building, Gower Street, London WC1E 6BT, UK
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Gungordu Er S, Tabish TA, Edirisinghe M, Matharu RK. Antiviral properties of porous graphene, graphene oxide and graphene foam ultrafine fibers against Phi6 bacteriophage. Front Med (Lausanne) 2022; 9:1032899. [PMID: 36507513 PMCID: PMC9730705 DOI: 10.3389/fmed.2022.1032899] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2022] [Accepted: 11/07/2022] [Indexed: 11/25/2022] Open
Abstract
As the world has experienced in the Coronavirus Disease 2019 pandemic, viral infections have devastating effects on public health. Personal protective equipment with high antiviral features has become popular among healthcare staff, researchers, immunocompromised people and more to minimize this effect. Graphene and its derivatives have been included in many antimicrobial studies due to their exceptional physicochemical properties. However, scientific studies on antiviral graphene are much more limited than antibacterial and antifungal studies. The aim of this study was to produce nanocomposite fibers with high antiviral properties that can be used for personal protective equipment and biomedical devices. In this work, 10 wt% polycaprolactone-based fibers were prepared with different concentrations (0.1, 0.5, 1, 2, 4 w/w%) of porous graphene, graphene oxide and graphene foam in acetone by using electrospinning. SEM, FTIR and XRD characterizations were applied to understand the structure of fibers and the presence of materials. According to SEM results, the mean diameters of the porous graphene, graphene oxide and graphene foam nanofibers formed were around 390, 470, and 520 nm, respectively. FTIR and XRD characterization results for 2 w/w% concentration nanofibers demonstrated the presence of graphene oxide, porous graphene and graphene foam nanomaterials in the fiber. The antiviral properties of the formed fibers were tested against Pseudomonas phage Phi6. According to the results, concentration-dependent antiviral activity was observed, and the strongest viral inhibition graphene oxide-loaded nanofibers were 33.08 ± 1.21% at the end of 24 h.
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Affiliation(s)
- Seda Gungordu Er
- Department of Mechanical Engineering, University College London, London, United Kingdom
| | - Tanveer A. Tabish
- Department of Mechanical Engineering, University College London, London, United Kingdom
- Radcliffe Department of Medicine, University of Oxford, Oxford, United Kingdom
- Department of Engineering Science, University of Oxford Begbroke Science Park, Oxford, United Kingdom
| | - Mohan Edirisinghe
- Department of Mechanical Engineering, University College London, London, United Kingdom
| | - Rupy Kaur Matharu
- Department of Civil, Environmental and Geomatic Engineering, University College London, London, United Kingdom
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Adzic F, Roberts BM, Hathway EA, Kaur Matharu R, Ciric L, Wild O, Cook M, Malki-Epshtein L. A post-occupancy study of ventilation effectiveness from high-resolution CO 2 monitoring at live theatre events to mitigate airborne transmission of SARS-CoV-2. Build Environ 2022; 223:109392. [PMID: 35937085 PMCID: PMC9339161 DOI: 10.1016/j.buildenv.2022.109392] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2022] [Revised: 06/24/2022] [Accepted: 07/10/2022] [Indexed: 05/20/2023]
Abstract
Mass-gathering events were closed around the world in 2020 to minimise the spread of the SARS-CoV-2 virus. Emerging research on the transmission of SARS-CoV-2 emphasised the importance of sufficient ventilation. This paper presents the results of an indoor air quality (IAQ) monitoring study over 82 events in seven mechanically ventilated auditoria to support the UK government Events Research Programme. Indoor carbon dioxide concentration was measured at high resolution before, during, and after occupancy to allow for assessment of the ventilation systems. Generally, good indoor air quality was measured in all auditoria, with average IAQ found to be excellent or very good for 70% of spaces. In some auditoria, spatial variation in IAQ was identified, indicating poor mixing of the air. In addition, surface and air samples were taken and analysed for the presence of bacteria by culture and SARS-CoV-2 using RT-qPCR in one venue. SARS-CoV-2 RNA was detected on a small number of surfaces at very low copy numbers, which are unlikely to pose an infection risk. Under the ventilation strategies and occupancy levels investigated, it is likely that most theatres pose a low risk of long-range transmission of COVID-19.
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Affiliation(s)
- Filipa Adzic
- Department of Civil, Environmental and Geomatic Engineering, University College London, UK
| | - Ben M Roberts
- Building Energy Research Group, School of Architecture, Building and Civil Engineering, Loughborough University, UK
| | | | - Rupy Kaur Matharu
- Department of Civil, Environmental and Geomatic Engineering, University College London, UK
| | - Lena Ciric
- Department of Civil, Environmental and Geomatic Engineering, University College London, UK
| | - Oliver Wild
- Department of Civil, Environmental and Geomatic Engineering, University College London, UK
| | - Malcolm Cook
- Building Energy Research Group, School of Architecture, Building and Civil Engineering, Loughborough University, UK
| | - Liora Malki-Epshtein
- Department of Civil, Environmental and Geomatic Engineering, University College London, UK
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Matharu RK, Cheong YK, Ren G, Edirisinghe M, Ciric L. Exploiting the antiviral potential of intermetallic nanoparticles. Emergent Mater 2021; 5:1251-1260. [PMID: 34778706 PMCID: PMC8577177 DOI: 10.1007/s42247-021-00306-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/14/2021] [Accepted: 09/08/2021] [Indexed: 06/13/2023]
Abstract
Viral pandemic outbreaks cause a significant burden on global health as well as healthcare expenditure. The use of antiviral agents not only reduces the spread of viral pathogens but also diminishes the likelihood of them causing infection. The antiviral properties of novel copper-silver and copper-zinc intermetallic nanoparticles against Escherichia coli bacteriophage MS2 (RNA virus) and Escherichia coli bacteriophage T4 (DNA virus) are presented. The intermetallic nanoparticles were spherical in shape and were between 90 and 120 nm. Antiviral activity was assessed at concentrations ranging from 0.05 to 2.0 wt/v% for 3 and 24 h using DNA and RNA virus model organisms. Both types of nanoparticles demonstrated strong potency towards RNA viruses (> 89% viral reduction), whilst copper-silver nanoparticles were slightly more toxic towards DNA viruses when compared to copper-zinc nanoparticles. Both nanoparticles were then incorporated into polymeric fibres (carrier) to investigate their antiviral effectiveness when composited into polymeric matrices. Fibres containing copper-silver nanoparticles exhibited favourable antiviral properties, with a viral reduction of 75% after 3 h of exposure. The excellent antiviral properties of the intermetallic nanoparticles reported in this study against both types of viruses together with their unique material properties can make them significant alternatives to conventional antiviral therapies and decontamination agents.
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Affiliation(s)
- Rupy Kaur Matharu
- Department of Mechanical Engineering, University College London, Torrington Place, London, WC1E 7JE UK
- Department of Civil, Environmental and Geomatic Engineering, University College London, Gower Street, London, WC1E 6BT UK
| | - Yuen-Ki Cheong
- School of Engineering and Computer Science, University of Hertfordshire, Hatfield, AL10 9AB UK
| | - Guogang Ren
- School of Engineering and Computer Science, University of Hertfordshire, Hatfield, AL10 9AB UK
| | - Mohan Edirisinghe
- Department of Mechanical Engineering, University College London, Torrington Place, London, WC1E 7JE UK
| | - Lena Ciric
- Department of Civil, Environmental and Geomatic Engineering, University College London, Gower Street, London, WC1E 6BT UK
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Matharu RK, Tabish TA, Trakoolwilaiwan T, Mansfield J, Moger J, Wu T, Lourenço C, Chen B, Ciric L, Parkin IP, Edirisinghe M. Microstructure and antibacterial efficacy of graphene oxide nanocomposite fibres. J Colloid Interface Sci 2020; 571:239-252. [DOI: 10.1016/j.jcis.2020.03.037] [Citation(s) in RCA: 46] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2020] [Revised: 03/08/2020] [Accepted: 03/09/2020] [Indexed: 01/10/2023]
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Matharu RK, Porwal H, Chen B, Ciric L, Edirisinghe M. Viral Filtration Using Carbon-Based Materials. ACTA ACUST UNITED AC 2020; 3:e10107. [PMID: 32838209 PMCID: PMC7323107 DOI: 10.1002/mds3.10107] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2020] [Revised: 06/06/2020] [Accepted: 11/06/2020] [Indexed: 12/25/2022]
Abstract
Viral infections alone are a significant cause of morbidity and mortality worldwide and have a detrimental impact on global healthcare and socio‐economic development. The discovery of novel antiviral treatments has gained tremendous attention and support with the rising number of viral outbreaks. In this work, carbonaceous materials, including graphene nanoplatelets and graphene oxide nanosheets, were investigated for antiviral properties. The materials were characterized using scanning electron microscopy and transmission electron microscopy. Analysis showed the materials to be two‐dimensional with lateral dimensions ranging between 1 and 4 µm for graphene oxide and 110 ± 0.11 nm for graphene nanoplatelets. Antiviral properties were assessed against a DNA virus model microorganism at concentrations of 0.5, 1.0 and 2.0 wt/v%. Both carbonaceous nanomaterials exhibited potent antiviral properties and gave rise to a viral reduction of 100% across all concentrations tested. Graphene oxide nanosheets were then incorporated into polymeric fibres, and their antiviral behaviour was examined after 3 and 24 hr. A viral reduction of 39% was observed after 24 hr of exposure. The research presented here showcases, for the first time, the antiviral potential of several carbonaceous nanomaterials, also included in a carrier polymer. These outcomes can be translated and implemented in many fields and devices to prevent viral spread and infection.
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Affiliation(s)
- Rupy Kaur Matharu
- Department of Mechanical Engineering University College London Torrington Place London WC1E 7JE UK.,Department of Civil Environmental and Geomatic Engineering University College London London WC1E 6BT UK
| | - Harshit Porwal
- School of Engineering and Materials Science Queen Mary University of London Mile End Road London E1 4NS UK
| | - Biqiong Chen
- School of Mechanical and Aerospace Engineering Queen's University Belfast Stranmillis Road Belfast BT9 5AH UK
| | - Lena Ciric
- Department of Civil Environmental and Geomatic Engineering University College London London WC1E 6BT UK
| | - Mohan Edirisinghe
- Department of Mechanical Engineering University College London Torrington Place London WC1E 7JE UK
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Matharu RK, Ciric L, Ren G, Edirisinghe M. Comparative Study of the Antimicrobial Effects of Tungsten Nanoparticles and Tungsten Nanocomposite Fibres on Hospital Acquired Bacterial and Viral Pathogens. Nanomaterials (Basel) 2020; 10:nano10061017. [PMID: 32466574 PMCID: PMC7352352 DOI: 10.3390/nano10061017] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/04/2020] [Revised: 05/17/2020] [Accepted: 05/19/2020] [Indexed: 02/08/2023]
Abstract
A significant proportion of patients acquire hospital associated infections as a result of care within the NHS each year. Numerous antimicrobial strategies, such as antibiotics and surface modifications to medical facilities and instruments, have been devised in an attempt to reduce the incidence of nosocomial infections, but most have been proven unsuccessful and unsustainable due to antibiotic resistance. Therefore, the need to discover novel materials that can combat pathogenic microorganisms is ongoing. Novel technologies, such as the potential use of nanomaterials and nanocomposites, hold promise for reducing these infections in the fight against antimicrobial resistance. In this study, the antimicrobial activity of tungsten, tungsten carbide and tungsten oxide nanoparticles were tested against Escherichia coli, Staphylococcus aureus and bacteriophage T4 (DNA virus). The most potent nanoparticles, tungsten oxide, were incorporated into polymeric fibres using pressurised gyration and characterised using scanning electron microscopy and energy dispersive X-ray spectroscopy. The antimicrobial activity of tungsten oxide/polymer nanocomposite fibres was also studied. The results suggest the materials in this study promote mediation of the inhibition of microbial growth in suspension.
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Affiliation(s)
- Rupy Kaur Matharu
- Department of Mechanical Engineering, University College London, Torrington Place, London WC1E 7JE, UK;
- Department of Civil, Environmental & Geomatic Engineering, University College London, Chadwick Building, Gower Street, London WC1E 6BT, UK;
| | - Lena Ciric
- Department of Civil, Environmental & Geomatic Engineering, University College London, Chadwick Building, Gower Street, London WC1E 6BT, UK;
| | - Guogang Ren
- School of Engineering and Technology, University of Hertfordshire, Hatfield AL10 9AB, UK;
| | - Mohan Edirisinghe
- Department of Mechanical Engineering, University College London, Torrington Place, London WC1E 7JE, UK;
- Correspondence:
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Abstract
The exploration of nanocomposites has gained a strong research following over the last decade. These materials have been heavily exploited in several fields, with applications ranging from biosensors to biomedicine. Among these applications, great advances have been made in the field of microbiology, specifically as antimicrobial agents. This review aims to provide a comprehensive account of various nanocomposites that elucidate promising antimicrobial activity. The composition, physical and chemical properties, as well as the antimicrobial performance of these nanocomposites, are discussed in detail.
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Affiliation(s)
- Rupy Kaur Matharu
- Department of Mechanical Engineering, University College London, Torrington Place, London, WC1E 7JE, United Kingdom. Department of Civil, Environmental & Geomatic Engineering, University College London, Chadwick Building, Gower Street, London, WC1E 6BT, United Kingdom
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Abstract
A novel class of ultra-thin fibres, which affect microbial growth, were explored. The microbial properties of poly(methyl methacrylate) fibres containing 2, 4 and 8 wt% of graphene nanoplatelets (GNPs) were studied. GNPs were dispersed in a polymeric solution and processed using pressurized gyration. Electron microscopy was used to characterize GNP and fibre morphology. Scanning electron microscopy revealed the formation of beaded porous fibres. GNP concentration was found to dictate fibre morphology. As the GNP concentration increased, the average fibre diameter increased from 0.75 to 2.71 µm, while fibre porosity decreased. Gram-negative bacteria Escherichia coli and Pseudomonas aeruginosa were used to investigate the properties of 2, 4 and 8 wt% GNP-loaded fibres. GNP-loaded fibres (0 wt%) were used as the negative control. The fibres were incubated for 24 h with the bacteria; bacterial colony-forming units were enumerated by adopting the colony-counting method. The presence of 2 and 4 wt% GNP-loaded fibres promoted microbial growth, while 8 wt% GNP-loaded fibres showed antimicrobial activity. These results indicate that the minimum inhibitory concentration of GNPs required within a fibre is 8 wt%.
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Affiliation(s)
- Rupy Kaur Matharu
- Department of Mechanical Engineering, University College London, Torrington Place, London WC1E 7JE, UK
- Department of Civil, Environmental & Geomatic Engineering, University College London, Chadwick Building, Gower Street, London WC1E 6BT, UK
| | - Harshit Porwal
- School of Engineering and Materials Science, Queen Mary University of London, Mile End Road, London E1 4NS, UK
| | - Lena Ciric
- Department of Civil, Environmental & Geomatic Engineering, University College London, Chadwick Building, Gower Street, London WC1E 6BT, UK
| | - Mohan Edirisinghe
- Department of Mechanical Engineering, University College London, Torrington Place, London WC1E 7JE, UK
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Affiliation(s)
- Rupy Kaur Matharu
- Department of Mechanical Engineering; University College London; London WC1E 7JE United Kingdom
- Department of Civil, Environmental and Geomatic Engineering; University College London; London WC1E 7JE United Kingdom
| | - Zhalan Charani
- Department of Mechanical Engineering; University College London; London WC1E 7JE United Kingdom
| | - Lena Ciric
- Department of Civil, Environmental and Geomatic Engineering; University College London; London WC1E 7JE United Kingdom
| | | | - Mohan Edirisinghe
- Department of Mechanical Engineering; University College London; London WC1E 7JE United Kingdom
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