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Recent advancements in the bioinks and three-dimensional (3D) bioprinting methods used to fabricate vascular constructs are summarized herein. Critical biomechanical properties required to fabricate an ideal vascular graft are highlighted, as well as various testing methods have been outlined to evaluate the bio-fabricated grafts as per the Food and Drug Administration (FDA) and International Organization for Standardization (ISO) guidelines. Occlusive artery disease and cardiovascular disease are the major causes of death globally. These diseases are caused by the blockage in the arteries, which results in a decreased blood flow to the tissues of major organs in the body, such as the heart. Bypass surgery is often performed using a vascular graft to re-route the blood flow. Autologous grafts represent a gold standard for such bypass surgeries; however, these grafts may be unavailable due to the previous harvesting or possess a poor quality. Synthetic grafts serve well for medium to large-sized vessels, but they fail when used to replace small-diameter vessels, generally smaller than 6 mm. Various tissue engineering approaches have been used to address the urgent need for vascular graft that can withstand hemodynamic blood pressure and has the ability to grow and remodel. Among these approaches, 3D bioprinting offers an attractive solution to construct patient-specific vessel grafts with layered biomimetic structures.
Faraz Fazal; Sakshika Raghav; Anthony Callanan; Vasileios Koutsos; Norbert Radacsi. Recent advancements in the bioprinting of vascular grafts. Biofabrication 2021, 13, 032003 .
AMA StyleFaraz Fazal, Sakshika Raghav, Anthony Callanan, Vasileios Koutsos, Norbert Radacsi. Recent advancements in the bioprinting of vascular grafts. Biofabrication. 2021; 13 (3):032003.
Chicago/Turabian StyleFaraz Fazal; Sakshika Raghav; Anthony Callanan; Vasileios Koutsos; Norbert Radacsi. 2021. "Recent advancements in the bioprinting of vascular grafts." Biofabrication 13, no. 3: 032003.
There is a high demand for small diameter vascular grafts having mechanical and biological properties similar to that of living tissues. Tissue-engineered vascular grafts using current methods have often failed due to the mismatch of mechanical properties between the implanted graft and living tissues. To address this limitation, a hybrid bioprinting-electrospinning system is developed for vascular tissue engineering applications. The setup is capable of producing layered structure from electrospun fibres and cell-laden hydrogel. A Creality3D Ender 3D printer has been modified into a hybrid setup having one bioprinting head and two electrospinning heads. Fortus 250mc and Flashforge Creator Pro 3D printers were used to print parts using acrylonitrile butadiene styrene (ABS) and polylactic acid (PLA) polymers. An Arduino mega 2560 and a Ramps 1.4 controller board were selected to control the functions of the hybrid bioprinting setup. The setup was tested successfully to print a tubular construct around a rotating needle.
Faraz Fazal; Francisco Javier Diaz Sanchez; Muhammad Waqas; Vasileios Koutsos; Anthony Callanan; Norbert Radacsi. A modified 3D printer as a hybrid bioprinting-electrospinning system for use in vascular tissue engineering applications. Medical Engineering & Physics 2021, 94, 52 -60.
AMA StyleFaraz Fazal, Francisco Javier Diaz Sanchez, Muhammad Waqas, Vasileios Koutsos, Anthony Callanan, Norbert Radacsi. A modified 3D printer as a hybrid bioprinting-electrospinning system for use in vascular tissue engineering applications. Medical Engineering & Physics. 2021; 94 ():52-60.
Chicago/Turabian StyleFaraz Fazal; Francisco Javier Diaz Sanchez; Muhammad Waqas; Vasileios Koutsos; Anthony Callanan; Norbert Radacsi. 2021. "A modified 3D printer as a hybrid bioprinting-electrospinning system for use in vascular tissue engineering applications." Medical Engineering & Physics 94, no. : 52-60.
Fiber-metal laminates (FMLs) offer the superior characteristics of polymer composites (i.e., light weight, high strength and stiffness) with the ductility and fracture strength of metals. The bond strength between the two dissimilar materials, composite and metal, dictates the properties and performance of the FMLs. The bonding becomes more critical when the polymer matrix is thermoplastic and hydrophobic in nature. This work employed a novel bonding technique between thermoplastic composites and a metal layer using six different combinations of organic coatings. The flexural, and interlaminar shear strength of the thermoplastic fiber metal laminates (TP-FMLs) were examined to investigate the bond strengths in the different cases along with fracture characteristics revealed from the tested samples using scanning electron microscopy. The viscoelastic performance of the fabricated TP-FMLs were also investigated using the dynamic mechanical thermal analysis method.
Colin Robert; Dimitrios Mamalis; Winifred Obande; Vasileios Koutsos; Conchúr M. Ó Brádaigh; Dipa Ray. Interlayer bonding between thermoplastic composites and metals by in‐situ polymerization technique. Journal of Polymer Science 2021, 51188 .
AMA StyleColin Robert, Dimitrios Mamalis, Winifred Obande, Vasileios Koutsos, Conchúr M. Ó Brádaigh, Dipa Ray. Interlayer bonding between thermoplastic composites and metals by in‐situ polymerization technique. Journal of Polymer Science. 2021; ():51188.
Chicago/Turabian StyleColin Robert; Dimitrios Mamalis; Winifred Obande; Vasileios Koutsos; Conchúr M. Ó Brádaigh; Dipa Ray. 2021. "Interlayer bonding between thermoplastic composites and metals by in‐situ polymerization technique." Journal of Polymer Science , no. : 51188.
This technical note provides a step-by-step guide for the design and construction of a temperature-controlled nozzle-free electrospinning device. The equipment uses a rotating mandrel partially immersed within a polymer solution to produce fibers in an upward motion by inducing the formation of multiple Taylor cones and subsequently multi-jetting out of an electrified open surface. Free-surface electrospinning can overcome limitations and drawbacks associated with single and multi-nozzle spinneret configurations, such as low yield, limited production capacity, nonuniform electric field distribution, and clogging. Most importantly, this lab-scaled high-throughput device can provide an alternative economical route for needleless electrospinning research, in contrast to the high costs associated with industrially available upscaling equipment. Among the device's technical specifications, a key feature is a cryo-collector mandrel, capable of collecting fibers in sub-zero temperatures, which can induce ultra-porous nanostructures, wider pores, and subsequent in-depth penetration of cells. A multi-channel gas chamber allows the conditioning of the atmosphere, temperature, and airflow, while the chamber's design averts user exposure to the high-voltage components. All the CAD files and point-by-point assembly instructions, along with a list of the materials used, are provided.
Muhammad Waqas; Antonios Keirouz; Maria Kana Sanira Putri; Faraz Fazal; Francisco Javier Diaz Sanchez; Dipa Ray; Vasileios Koutsos; Norbert Radacsi. Design and development of a nozzle-free electrospinning device for the high-throughput production of biomaterial nanofibers. Medical Engineering & Physics 2021, 92, 80 -87.
AMA StyleMuhammad Waqas, Antonios Keirouz, Maria Kana Sanira Putri, Faraz Fazal, Francisco Javier Diaz Sanchez, Dipa Ray, Vasileios Koutsos, Norbert Radacsi. Design and development of a nozzle-free electrospinning device for the high-throughput production of biomaterial nanofibers. Medical Engineering & Physics. 2021; 92 ():80-87.
Chicago/Turabian StyleMuhammad Waqas; Antonios Keirouz; Maria Kana Sanira Putri; Faraz Fazal; Francisco Javier Diaz Sanchez; Dipa Ray; Vasileios Koutsos; Norbert Radacsi. 2021. "Design and development of a nozzle-free electrospinning device for the high-throughput production of biomaterial nanofibers." Medical Engineering & Physics 92, no. : 80-87.
Nanofibers of the poorly water-soluble antibiotic ciprofloxacin (CIP) were fabricated in the form of an amorphous solid dispersion by using poly(vinyl pyrrolidone) as a polymer matrix, by the low-cost electrospinning method. The solubility of the nanofibers as well as their in vitro diffusion were remarkably higher than those of the CIP powder or the physical mixture of the two components. The fiber size and morphology were optimized, and it was found that the addition of the CIP to the electrospinning solution decreased the nanofiber diameter, leading to an increased specific surface area. Structural characterization confirmed the interactions between the drug and the polymer and the amorphous state of CIP inside the nanofibers. Since the solubility of CIP is pH-dependent, the in vitro solubility and dissolution studies were executed at different pH levels. The nanofiber sample with the finest morphology demonstrated a significant increase in solubility both in water and pH 7.4 buffer. Single medium and two-stage biorelevant dissolution studies were performed, and the release mechanism was described by mathematical models. Besides, in vitro diffusion from pH 6.8 to pH 7.4 notably increased when compared with the pure drug and physical mixture. Ciprofloxacin-loaded poly(vinyl pyrrolidone) (PVP) nanofibers can be considered as fast-dissolving formulations with improved physicochemical properties.
Luca Uhljar; Sheng Kan; Norbert Radacsi; Vasileios Koutsos; Piroska Szabó-Révész; Rita Ambrus. In Vitro Drug Release, Permeability, and Structural Test of Ciprofloxacin-Loaded Nanofibers. Pharmaceutics 2021, 13, 556 .
AMA StyleLuca Uhljar, Sheng Kan, Norbert Radacsi, Vasileios Koutsos, Piroska Szabó-Révész, Rita Ambrus. In Vitro Drug Release, Permeability, and Structural Test of Ciprofloxacin-Loaded Nanofibers. Pharmaceutics. 2021; 13 (4):556.
Chicago/Turabian StyleLuca Uhljar; Sheng Kan; Norbert Radacsi; Vasileios Koutsos; Piroska Szabó-Révész; Rita Ambrus. 2021. "In Vitro Drug Release, Permeability, and Structural Test of Ciprofloxacin-Loaded Nanofibers." Pharmaceutics 13, no. 4: 556.
Fouling remains a prevalent and serious problem in industries using membrane processes. Efforts to mitigate fouling are improving, however, membrane fouling cannot be completely eliminated. Therefore fouling control via development of sustainable cleaning methods are crucial. Despite osmotic backwashing showing promise, little is understood about this cleaning method for removal of fouling from reverse osmosis (RO) membranes. This paper systematically examines how organic fouling characteristics and osmotic backwashing parameters influence cleaning efficiency. Alginic acid was used as a model foulant and numerous microscopy techniques, including confocal microscopy, scanning electron microscopy and atomic force microscopy were used to examine the membrane fouling before and after cleaning to gain a clearer understanding of the mechanisms involved. Increasing CaCl2 concentration in the fouling solution resulted in an increase in fouling layer thickness from 37 to 179 μm, due to the complexation of Ca2+ and the carboxyl groups in the alginate. Osmotic backwashing efficiency with 0.7 M NaCl decreased as the fouling layer became thicker and the pure water flux (PWF) recovery decreased from 92% to 81%. Osmotic backwashing efficiency also decreased with increasing initial permeate flux, as less fouling was removed: the fouling generated at higher initial fluxes is largely irreversible, resulting in a denser and more compact fouling layer. In an effort to increase osmotic backwashing flux, a CaCl2 draw solution was used, however, the Ca2+ ions were found to interact with the alginate in the fouling layer, rendering this method inefficient, when compared to NaCl draw solutions which originated similar osmotic backwashing fluxes. Interestingly, the fouling layer was found to swell from 16 μm to 141 μm, when osmotic backwashing was carried out with a NaCl draw solution, followed by contact with a low ionic strength solution used for PWF testing. This phenomenon does not occur to the same extent after backwashing with CaCl2. The same trends were obtained for bovine serum albumin (BSA) fouling, whilst humic acid (HA) did not display any swelling phenomena. However, it showed the same cleaning inefficiency when using CaCl2 as a draw solution.
Sorcha Daly; Ashley Allen; Vasileios Koutsos; Andrea J.C. Semião. Influence of organic fouling layer characteristics and osmotic backwashing conditions on cleaning efficiency of RO membranes. Journal of Membrane Science 2020, 616, 118604 .
AMA StyleSorcha Daly, Ashley Allen, Vasileios Koutsos, Andrea J.C. Semião. Influence of organic fouling layer characteristics and osmotic backwashing conditions on cleaning efficiency of RO membranes. Journal of Membrane Science. 2020; 616 ():118604.
Chicago/Turabian StyleSorcha Daly; Ashley Allen; Vasileios Koutsos; Andrea J.C. Semião. 2020. "Influence of organic fouling layer characteristics and osmotic backwashing conditions on cleaning efficiency of RO membranes." Journal of Membrane Science 616, no. : 118604.
The through‐thickness conductivity of carbon fiber reinforced polymer (CFRP) composite was increased by incorporating multiwalled carbon nanotubes in the interlaminar region. Carbon nanotubes (CNTs) were dispersed in a polyethylenimine (PEI) binder, which was then coated onto the carbon fiber fabric. Standard vacuum‐assisted resin infusion process was applied to fabricate the composite laminates. This modification technique aims to enhance the electrical conductivity in through‐thickness direction for the purpose of nondestructive testing, damage detection, and electromagnetic interference shielding. CNT concentrations ranging from 0 to 0.75 wt% were used and compared to pristine CFRP samples (reference). The through‐thickness conductivity of the CFRP exhibited an improvement of up to 781% by adopting this technique. However, the dispersion of CNT in PEI led to a viscosity increase and poor wetting properties which resulted in the formation of voids/defects, poor adhesion (as shown in scanning electron micrographs) and the deterioration of the mechanical properties as manifested by interlaminar shear strength and dynamic mechanical analysis measurements.
Colin Robert; Witiwat Best Thitasiri; Dimitrios Mamalis; Zakareya Elmo Hussein; Muhammad Waqas; Dipa Ray; Norbert Radacsi; Vasileios Koutsos. Improving through‐thickness conductivity of carbon fiber reinforced polymer using carbon nanotube/polyethylenimine at the interlaminar region. Journal of Applied Polymer Science 2020, 138, 1 .
AMA StyleColin Robert, Witiwat Best Thitasiri, Dimitrios Mamalis, Zakareya Elmo Hussein, Muhammad Waqas, Dipa Ray, Norbert Radacsi, Vasileios Koutsos. Improving through‐thickness conductivity of carbon fiber reinforced polymer using carbon nanotube/polyethylenimine at the interlaminar region. Journal of Applied Polymer Science. 2020; 138 (5):1.
Chicago/Turabian StyleColin Robert; Witiwat Best Thitasiri; Dimitrios Mamalis; Zakareya Elmo Hussein; Muhammad Waqas; Dipa Ray; Norbert Radacsi; Vasileios Koutsos. 2020. "Improving through‐thickness conductivity of carbon fiber reinforced polymer using carbon nanotube/polyethylenimine at the interlaminar region." Journal of Applied Polymer Science 138, no. 5: 1.
Leading edge erosion (LEE) affects almost all wind turbines, reducing their annual energy production and lifetime profitability. This study presents results of an investigation into 18 operational wind farms to assess the validity of the current literature consensus surrounding LEE. Much of the historical research focuses on rain erosion, implying that this is the predominant causal factor. However, this study showed that the impact of excessive airborne particles from seawater aerosols or from adverse local environments such as nearby quarries greatly increases the levels of LEE. Current testing of leading edge protection coatings or tapes is based on a rain erosion resistivity test, which does little to prove its ability to withstand solid particle erosion and may drive coating design in the wrong direction. Furthermore, it was shown that there is little correlation between test results and actual field performance. A method of monitoring the expected level of erosion on an operational wind turbine due to rain erosion is also presented. Finally, the energy losses associated with LEE on an operational wind farm are examined, with the average annual energy production dropping by 1.8% due to medium levels of erosion, with the worst affected turbine experiencing losses of 4.9%.
Hamish Law; Vasileios Koutsos. Leading edge erosion of wind turbines: Effect of solid airborne particles and rain on operational wind farms. Wind Energy 2020, 23, 1 .
AMA StyleHamish Law, Vasileios Koutsos. Leading edge erosion of wind turbines: Effect of solid airborne particles and rain on operational wind farms. Wind Energy. 2020; 23 (10):1.
Chicago/Turabian StyleHamish Law; Vasileios Koutsos. 2020. "Leading edge erosion of wind turbines: Effect of solid airborne particles and rain on operational wind farms." Wind Energy 23, no. 10: 1.
AFM force spectroscopy was utilised to measure the interactions between latex and carbon black nanoparticles in neutral ultrapure water and basic ultrapure water with 0.7% ammonia (pH of 11.6 ± 0.05) by weight added. For the first time, carbon black nanoparticles were adhered to AFM tips with epoxy using force spectroscopy techniques and characterised using SEM and AFM. The carbon-functionalised tips were then utilised to interact with thin films (prepared from concentrated and field latex suspensions) in the two liquid media. The results demonstrated that both attractive (during tip approach) and adhesive (during tip retraction) forces were considerably greater between the latex and carbon nanoparticles when the experiments were carried out in ultrapure water compared to ultrapure water with 0.7% ammonia. This was because the basic ammonia solution increased the negative surface charges of the latex and carbon particles which was confirmed by zeta potential measurements. Therefore, in the ammonia solution, only repulsion was observed on the tip approach and only small amounts of adhesion were observed on the tip retraction. Furthermore, the results demonstrated that despite the different processing and treatment of the concentrated and field latex samples, their interactions with the carbon black nanoparticles were similar in each medium. This study directly measures the interactions between carbon black nanoparticles and natural rubber latex, which has a significance for the manufacturing of automotive tyres and other polymer/carbon composites.
Jake McClements; Mei Zhang; Norbert Radacsi; Vasileios Koutsos. Measuring the interactions between carbon black nanoparticles and latex thin films in aqueous media using AFM force spectroscopy. Colloids and Surfaces A: Physicochemical and Engineering Aspects 2020, 603, 124920 .
AMA StyleJake McClements, Mei Zhang, Norbert Radacsi, Vasileios Koutsos. Measuring the interactions between carbon black nanoparticles and latex thin films in aqueous media using AFM force spectroscopy. Colloids and Surfaces A: Physicochemical and Engineering Aspects. 2020; 603 ():124920.
Chicago/Turabian StyleJake McClements; Mei Zhang; Norbert Radacsi; Vasileios Koutsos. 2020. "Measuring the interactions between carbon black nanoparticles and latex thin films in aqueous media using AFM force spectroscopy." Colloids and Surfaces A: Physicochemical and Engineering Aspects 603, no. : 124920.
Here, we report on the inexpensive fabrication of an electrospray/electrospinning setup by fused deposition modelling (FDM) 3D printing and provide the files and parameters needed to print this versatile device. Both electrospray and electrospinning technologies are widely used for pharmaceutical, healthcare and bioengineering applications. The setup was designed to be modular, thus its parts can be exchanged easily. The design provides a safe setup, ensuring that the users are not exposed to the high voltage parts of the setup. PLA, PVA, and a thermoplastic elastomer filament were used for the 3D printing. The filament cost was $100 USD and the rig was printed in 6 days. An Ultimaker 3 FDM 3D printer was used with dual print heads, and the PVA was used as a water-soluble support structure. The end part of the setup had several gas channels, allowing a uniform gas flowing against the direction of the nanoparticles/nanofibers, enhancing the drying process by enhancing the evaporation rate. The setup was tested in both electrospray and electrospinning modes successfully. Both the .sldprt and .stl files are provided for free download.
Jing Huang; Vasileios Koutsos; Norbert Radacsi. Low-cost FDM 3D-printed modular electrospray/electrospinning setup for biomedical applications. 3D Printing in Medicine 2020, 6, 1 -7.
AMA StyleJing Huang, Vasileios Koutsos, Norbert Radacsi. Low-cost FDM 3D-printed modular electrospray/electrospinning setup for biomedical applications. 3D Printing in Medicine. 2020; 6 (1):1-7.
Chicago/Turabian StyleJing Huang; Vasileios Koutsos; Norbert Radacsi. 2020. "Low-cost FDM 3D-printed modular electrospray/electrospinning setup for biomedical applications." 3D Printing in Medicine 6, no. 1: 1-7.
In this work, a nozzle-free electrospinning device was built to obtain high-throughput production of silk fibroin-based biocompatible composite fibers with tunable wettability. Synthetic biomaterials tend to present suboptimal cell growth and proliferation, with many studies linking this phenomenon to the hydrophobicity of such surfaces. In this study, electrospun mats consisting of Poly(caprolactone) blended with variant forms of Poly(glycerol sebacate) (PGS) and regenerated silk fibroin were fabricated. The main aim of this work was the development of fiber mats with tunable hydrophobicity/hydrophilicity properties depending on the esterification degree and concentration of PGS. A variation of the conventional protocol used for the extraction of silk fibroin from Bombyx mori cocoons was employed, achieving significantly increased yields of the protein, in a third of the time required via the conventional extraction protocol. By altering the surface properties of the electrospun membranes, the trinary composite biomaterial presented good in vitro fibroblast attachment behavior and optimal growth, indicating the potential of such constructs towards the development of an artificial skin-like platform that can aid wound healing and skin regeneration.
Antonios Keirouz; Mariia Zakharova; Jaehoon Kwon; Colin Robert; Vasileios Koutsos; Anthony Callanan; Xianfeng Chen; Giuseppino Fortunato; Norbert Radacsi. High-throughput production of silk fibroin-based electrospun fibers as biomaterial for skin tissue engineering applications. Materials Science and Engineering: C 2020, 112, 110939 .
AMA StyleAntonios Keirouz, Mariia Zakharova, Jaehoon Kwon, Colin Robert, Vasileios Koutsos, Anthony Callanan, Xianfeng Chen, Giuseppino Fortunato, Norbert Radacsi. High-throughput production of silk fibroin-based electrospun fibers as biomaterial for skin tissue engineering applications. Materials Science and Engineering: C. 2020; 112 ():110939.
Chicago/Turabian StyleAntonios Keirouz; Mariia Zakharova; Jaehoon Kwon; Colin Robert; Vasileios Koutsos; Anthony Callanan; Xianfeng Chen; Giuseppino Fortunato; Norbert Radacsi. 2020. "High-throughput production of silk fibroin-based electrospun fibers as biomaterial for skin tissue engineering applications." Materials Science and Engineering: C 112, no. : 110939.
As the use of carbon fibre reinforced polymers (CFRP) is continuing to increase in engineering applications, more functionalities will be required. Having an enhanced through-thickness electrical conductivity can be a useful functionality for CFRPs which will minimise their damage from lightning strikes, and will help in their real-time monitoring. For most modification methods there is an adverse effect on the manufacturing and the fibre volume fraction, which influence the mechanical properties of the resulting composites. Simultaneous improvement of multiple properties of CFRPs is difficult, and as such the ways in which different materials and processes improve properties of CFRPs need to be understood in depth. This review discusses research that attempts to improve the through-thickness electrical conductivity of CFRPs with interest in the effects on mechanical properties, specifically interlaminar fracture toughness. The last section discusses the effect and use of these methods to improve structural health monitoring (SHM) of CFRPs.
S.C. Brown; C. Robert; Vasileios Koutsos; D. Ray. Methods of modifying through-thickness electrical conductivity of CFRP for use in structural health monitoring, and its effect on mechanical properties – A review. Composites Part A: Applied Science and Manufacturing 2020, 133, 105885 .
AMA StyleS.C. Brown, C. Robert, Vasileios Koutsos, D. Ray. Methods of modifying through-thickness electrical conductivity of CFRP for use in structural health monitoring, and its effect on mechanical properties – A review. Composites Part A: Applied Science and Manufacturing. 2020; 133 ():105885.
Chicago/Turabian StyleS.C. Brown; C. Robert; Vasileios Koutsos; D. Ray. 2020. "Methods of modifying through-thickness electrical conductivity of CFRP for use in structural health monitoring, and its effect on mechanical properties – A review." Composites Part A: Applied Science and Manufacturing 133, no. : 105885.
Atomic force microscopy (AFM) was utilized to investigate the force associated with chain pull-out and single chain desorption of poly(styrene-co-butadiene) random copolymer thin films on mica, silicon, and graphite substrates. Chain pull-out events were common and produced a force of 20–25 pN. The polymer desorption force was strongest on the graphite substrate and weakest on the mica, which agreed with the calculated work of adhesion for each system and the substrate hydrophobicity. Furthermore, it was demonstrated that there was a systematic order to when each of these phenomena occurred during the tip retraction from the surface, which provided information about the structure of the thin films.
Jake McClements; Vasileios Koutsos. Thin Polymer Film Force Spectroscopy: Single Chain Pull-out and Desorption. ACS Macro Letters 2020, 9, 152 -157.
AMA StyleJake McClements, Vasileios Koutsos. Thin Polymer Film Force Spectroscopy: Single Chain Pull-out and Desorption. ACS Macro Letters. 2020; 9 (2):152-157.
Chicago/Turabian StyleJake McClements; Vasileios Koutsos. 2020. "Thin Polymer Film Force Spectroscopy: Single Chain Pull-out and Desorption." ACS Macro Letters 9, no. 2: 152-157.
This study investigates the evaporation of sessile pure water and nano-suspension drops on viscoelastic polydimethylsiloxane (PDMS) films. We varied the viscoelasticity of the PDMS films by controlling the curing ratio, and categorized them into three types: stiff (10:1, 20:1, 40:1), soft (60:1, 80:1), and very soft (100:1, 120:1, 140:1, 160:1). On stiff surfaces, pure water drops initially evaporate in a constant contact radius (CCR) mode, followed by a constant contact angle (CCA) mode, and finally in a mixed mode of evaporation. Nano-suspension drops follow the same trend as water drops but with a difference towards the end of their lifetimes, when a short second CCR mode is observed. Complete evaporation of nano-suspension drops on stiff substrates leads to particle deposition patterns similar to a coffee ring with cracks and deposition tails. On soft surfaces, the initial spreading is followed by a pseudo-CCR mode. Complete evaporation of nano-suspension drops on soft substrates leads to deposits in the form of a uniform ring with a sharp ox-horn profile. Unexpectedly, the initial spreading is followed by a mixed mode on very soft substrates, on which wetting ridges pulled up by the vertical component of surface tension are clearly observed in the vicinity of the contact line. As the evaporation proceeds, the decreasing contact angle breaks the force balance in the horizontal direction at the contact line and gives rise to a net horizontal force, which causes the contact line to recede, transferring the horizontal force to the wetting ridge. Due to the viscoelastic nature of the very soft substrate, this horizontal force acting on the wetting ridge cannot be completely countered by the bulk of the substrate underneath. As a result, the wetting ridge moves horizontally in a viscous-flow way, which also enables the contact line to be continuously anchored to the ridge and to recede relative to the bulk of the substrate. Consequently, a mixed mode of evaporation occurs. Complete evaporation of nano-suspension drops on very soft substrates leads to finger-like deposits.
Yuhong Chen; Alexandros Askounis; Vasileios Koutsos; Prashant Valluri; Yasuyuki Takata; Stephen Kenneth Wilson; Khellil Sefiane. On the Effect of Substrate Viscoelasticity on the Evaporation Kinetics and Deposition Patterns of Nanosuspension Drops. Langmuir 2019, 36, 204 -213.
AMA StyleYuhong Chen, Alexandros Askounis, Vasileios Koutsos, Prashant Valluri, Yasuyuki Takata, Stephen Kenneth Wilson, Khellil Sefiane. On the Effect of Substrate Viscoelasticity on the Evaporation Kinetics and Deposition Patterns of Nanosuspension Drops. Langmuir. 2019; 36 (1):204-213.
Chicago/Turabian StyleYuhong Chen; Alexandros Askounis; Vasileios Koutsos; Prashant Valluri; Yasuyuki Takata; Stephen Kenneth Wilson; Khellil Sefiane. 2019. "On the Effect of Substrate Viscoelasticity on the Evaporation Kinetics and Deposition Patterns of Nanosuspension Drops." Langmuir 36, no. 1: 204-213.
Carbon fibres with three different sizing agents were used to manufacture unidirectional composites based on a powder epoxy resin. Powder epoxy processing was investigated as a route for fast, cost-effective manufacturing of out-of-autoclave composites compared to more time-consuming vacuum infusion technologies. In this work, a heat-activated epoxy powder was used as a resin system in low-cost vacuum-bag-only prepregs for thick composite parts that are required in the renewable energy industry (e.g. wind turbine blade roots). The importance of interfacial bonding between fibres and the matrix is shown and the impact on the ultimate mechanical performance of the manufactured composites demonstrated. The surface characteristics of the sizing on the carbon fibres were investigated using atomic force microscopy (AFM) and Raman spectroscopy. Results showed that the amount of sizing on the fibres' surfaces was inextricably linked with surface roughness and coverage. This in turn influenced the mechanical and chemical interlocking phenomena occurring at the fibre/matrix interface. The composites’ mechanical performance was evaluated using tensile, flexural and interlaminar fracture toughness tests. Fractographic analysis using optical and scanning electron microscopy (SEM) was likewise employed to analyse the fracture surfaces of the tested/failed composites. Interlaminar fracture toughness testing (DCB Mode-I) revealed that the interfacial adhesion differences could alter the fracture resistance of the composites, hence emphasizing the importance of the interfacial bonding strength between the polymer matrix and the carbon fibres.
Dimitrios Mamalis; James J. Murray; Jake McClements; Dimitrios Tsikritsis; Vasileios Koutsos; Edward D. McCarthy; Conchúr Ó Brádaigh. Novel carbon-fibre powder-epoxy composites: Interface phenomena and interlaminar fracture behaviour. Composites Part B: Engineering 2019, 174, 107012 .
AMA StyleDimitrios Mamalis, James J. Murray, Jake McClements, Dimitrios Tsikritsis, Vasileios Koutsos, Edward D. McCarthy, Conchúr Ó Brádaigh. Novel carbon-fibre powder-epoxy composites: Interface phenomena and interlaminar fracture behaviour. Composites Part B: Engineering. 2019; 174 ():107012.
Chicago/Turabian StyleDimitrios Mamalis; James J. Murray; Jake McClements; Dimitrios Tsikritsis; Vasileios Koutsos; Edward D. McCarthy; Conchúr Ó Brádaigh. 2019. "Novel carbon-fibre powder-epoxy composites: Interface phenomena and interlaminar fracture behaviour." Composites Part B: Engineering 174, no. : 107012.
Larysa Fomenko; Serzh Lubenets; V. D. Natsik; A. I. Prokhvatilov; N. N. Galtsov; Q. Q. Li; Vasileios Koutsos. Investigation of the low-temperature mechanical behavior of elastomers and their carbon nanotube composites using microindentation. Low Temperature Physics 2019, 45, 568 -576.
AMA StyleLarysa Fomenko, Serzh Lubenets, V. D. Natsik, A. I. Prokhvatilov, N. N. Galtsov, Q. Q. Li, Vasileios Koutsos. Investigation of the low-temperature mechanical behavior of elastomers and their carbon nanotube composites using microindentation. Low Temperature Physics. 2019; 45 (5):568-576.
Chicago/Turabian StyleLarysa Fomenko; Serzh Lubenets; V. D. Natsik; A. I. Prokhvatilov; N. N. Galtsov; Q. Q. Li; Vasileios Koutsos. 2019. "Investigation of the low-temperature mechanical behavior of elastomers and their carbon nanotube composites using microindentation." Low Temperature Physics 45, no. 5: 568-576.
Microbubbles (MBs), which are used as ultrasonic contrast agents, have distinct acoustic signatures which enable them to significantly enhance visualisation of the vasculature. Research is progressing to develop MBs which act as drug/gene delivery vehicles for site-specific therapeutics. In order to manufacture effective theranostic vehicles, it is imperative to understand the mechanical and nanostructural properties of these agents; this will enrich the understanding of how the structural, biophysical and chemical properties of these bubbles impact their functionality. We produced microfluidic phospholipid-based MBs due to their favourable properties, such as biocompatibility and echogenicity, as well as the ability to modify the shell for targeting applications. We have drawn upon atomic force microscopy to conduct force-spectroscopy and tapping-mode imaging investigations. We have, for the first time to our knowledge, been able to accurately quantify the thickness and lipid configuration of phospholipid-shelled MBs - showing a trilayer as opposed to the conventional monolayer structure. Furthermore, we have measured MB stiffness and employed different mechanical theories to quantify the Young’s Modulus. We show that the Reissner theory is inappropriate for mechanical characterisation of phospholipid MBs, however, the Hertz model does offer biologically relevant comparisons. Analysis using the Alexander-de Gennes polymer brush theory has allowed us to provide new information regarding how the thickness of the polyethylene glycol brushes, end-grafted to our phospholipid microbubbles, changes with diameter.
Adeel S. Shafi; Jake McClements; Ibrahim Al-Baijan; Radwa H. Abou-Saleh; Carmel Moran; Vasileios Koutsos. Probing phospholipid microbubbles by atomic force microscopy to quantify bubble mechanics and nanostructural shell properties. Colloids and Surfaces B: Biointerfaces 2019, 181, 506 -515.
AMA StyleAdeel S. Shafi, Jake McClements, Ibrahim Al-Baijan, Radwa H. Abou-Saleh, Carmel Moran, Vasileios Koutsos. Probing phospholipid microbubbles by atomic force microscopy to quantify bubble mechanics and nanostructural shell properties. Colloids and Surfaces B: Biointerfaces. 2019; 181 ():506-515.
Chicago/Turabian StyleAdeel S. Shafi; Jake McClements; Ibrahim Al-Baijan; Radwa H. Abou-Saleh; Carmel Moran; Vasileios Koutsos. 2019. "Probing phospholipid microbubbles by atomic force microscopy to quantify bubble mechanics and nanostructural shell properties." Colloids and Surfaces B: Biointerfaces 181, no. : 506-515.
Facing the problems of shale hydration, swelling and borehole wall instability in shale gas drilling, a new type of amine terminated polyether (ATPE) shale inhibitor used in water-based drilling fluid is successfully synthesized through the method of leaving group. Using the yield of ATPE as index, orthogonal experiments are designed to determine the optimal reaction conditions. When the mole ratio of polyethylene glycol tosylate (PEG-OTs)/ethylenediamine is 1/3.6, mole ratio of PEG-OTs/triethylamine (acid binding agent) is 1/4, reaction time is 3.5 h and reaction temperature is 60 °C, the yield of ATPE is 91.12%. The structure and molecular weight of polyethylene glycol (PEG-400, a kind of oligomer), PEG-OTs and ATPE are characterized by Fourier transform infrared spectroscopy, nuclear magnetic resonance hydrogen spectroscopy (H1-NMR) and time of flight mass spectrometer. The characterization results show that the ATPE has a reasonable molecular weight, and the both hydroxyls of PEG-400 have been replaced by ethylenediamine. The inhibition property of ATPE, potassium chloride (KCl), potassium formate (KCOOH), methane-siliconic acid (FMS-1) and polymeric alcohol (JLX-B) are comparatively evaluated through shale rolling dispersion experiment, linear expansion experiment and laser particle size test. The results show that the ATPE has a better shale inhibition property than traditional inhibitors. The drilling fluid system performance evaluation results show that the system has good engineering application value with excellent rheological property, low fluid loss and good shale inhibition property, which guarantee the well-bore stability in shale gas drilling.
Xiaodong Bai; Xingyuan Zhang; Vasileios Koutsos; Zhihong Fu; Tao Ning; Yumei Luo; Song Zhou. Preparation and evaluation of amine terminated polyether shale inhibitor for water-based drilling fluid. SN Applied Sciences 2018, 1, 94 .
AMA StyleXiaodong Bai, Xingyuan Zhang, Vasileios Koutsos, Zhihong Fu, Tao Ning, Yumei Luo, Song Zhou. Preparation and evaluation of amine terminated polyether shale inhibitor for water-based drilling fluid. SN Applied Sciences. 2018; 1 (1):94.
Chicago/Turabian StyleXiaodong Bai; Xingyuan Zhang; Vasileios Koutsos; Zhihong Fu; Tao Ning; Yumei Luo; Song Zhou. 2018. "Preparation and evaluation of amine terminated polyether shale inhibitor for water-based drilling fluid." SN Applied Sciences 1, no. 1: 94.
There is an emerging need for a sustainable and cost-effective source of Supplementary Cementitious Material (SCM) to reduce clinker consumption, as well as an effective utilisation of the ceramic waste stream. This study explores the potential of two types of ceramic waste tiles as SCMs by examining the mineralogical properties and mechanical performance of mortar and paste samples prepared with 5%, 15% and 30%wt of the ceramics ground into powder form as cement replacement. Investigations were carried out over a 90-day curing period by using standard methods including the XRD, DTA/TGA and SEM analyses, as well as the compression test. The pozzolanic reactivity of both ceramics has been validated with the presence of the secondary hydration reaction. This study concludes that a mortar mix containing 15% White ceramic could achieve a compressive strength comparable to that of a standard Ordinary Portland Cement (OPC) mortar at 56 days after curing, and even exceeds the strength of the latter beyond this age.
E. Lasseuguette; S. Burns; D. Simmons; E. Francis; H.K. Chai; V. Koutsos; Y. Huang. Chemical, microstructural and mechanical properties of ceramic waste blended cementitious systems. Journal of Cleaner Production 2018, 211, 1228 -1238.
AMA StyleE. Lasseuguette, S. Burns, D. Simmons, E. Francis, H.K. Chai, V. Koutsos, Y. Huang. Chemical, microstructural and mechanical properties of ceramic waste blended cementitious systems. Journal of Cleaner Production. 2018; 211 ():1228-1238.
Chicago/Turabian StyleE. Lasseuguette; S. Burns; D. Simmons; E. Francis; H.K. Chai; V. Koutsos; Y. Huang. 2018. "Chemical, microstructural and mechanical properties of ceramic waste blended cementitious systems." Journal of Cleaner Production 211, no. : 1228-1238.
The manufacturing process of a new generation of thermoplastic fibre-metal laminates (TP-FMLs) was investigated. A vacuum assisted resin infusion method was used to produce the hybrid laminates. The effect of various chemical and physical treatments on the surface morphology of the aluminium (Al) alloy sheets and on the bond strength at the metal-composite interface was examined. The wettability, topography and chemical composition of the treated Al alloy sheets were studied by employing contact-angle goniometry, coherence scanning interferometry, profilometry and X-ray photoelectron spectroscopy. The results showed that the applied treatments on the Al alloy sheet changed the surface morphology and surface energy in a different degree, which in turn effectively enhanced the interfacial bond strength between the constituents. In addition, the flexural, interlaminar shear strength and interlaminar fracture toughness of the manufactured TP-FMLs with the optimum metal surface treatment were evaluated. The experimental results of the TP-FMLs were compared to an equivalent thermoplastic composite. The composite-metal interface and the fracture surface characteristics were examined under scanning electron microscopy. In-situ polymerisation was found to play a key role in bonding the treated Al alloy with the composite layer during manufacturing.
Dimitrios Mamalis; Winifred Obande; Vasileios Koutsos; Jane R. Blackford; Conchúr Ó Brádaigh; Dipa Ray. Novel thermoplastic fibre-metal laminates manufactured by vacuum resin infusion: The effect of surface treatments on interfacial bonding. Materials & Design 2018, 162, 331 -344.
AMA StyleDimitrios Mamalis, Winifred Obande, Vasileios Koutsos, Jane R. Blackford, Conchúr Ó Brádaigh, Dipa Ray. Novel thermoplastic fibre-metal laminates manufactured by vacuum resin infusion: The effect of surface treatments on interfacial bonding. Materials & Design. 2018; 162 ():331-344.
Chicago/Turabian StyleDimitrios Mamalis; Winifred Obande; Vasileios Koutsos; Jane R. Blackford; Conchúr Ó Brádaigh; Dipa Ray. 2018. "Novel thermoplastic fibre-metal laminates manufactured by vacuum resin infusion: The effect of surface treatments on interfacial bonding." Materials & Design 162, no. : 331-344.