This book is a senior level undergraduate and graduate textbook for a wide audience of engineering students taking a first course in CFD or Computer Aided Engineering. Fully course matched, with the ...most extensive and rigorous pedagogy and features of any book in the field. The first book in the field aimed at CFD users rather than developers.
Recent discoveries of two-dimensional transitional metal based materials have emerged as an excellent candidate for fabricating nanostructured flame-retardants. Herein, we report an eco-friendly ...flame-retardant for flexible polyurethane foam (PUF), which is synthesised by hybridising MXene (TiFormula: see text) with biomass materials including phytic acid (PA), casein, pectin, and chitosan (CH). Results show that coating PUFs with 3 layers of CH/PA/TiFormula: see text via layer-by-layer approach reduces the peak heat release and total smoke release by 51.1% and 84.8%, respectively. These exceptional improvements exceed those achieved by a CH/TiFormula: see text coating. To further understand the fundamental flame and smoke reduction phenomena, a pyrolysis model with surface regression was developed to simulate the flame propagation and char layer. A genetic algorithm was utilised to determine optimum parameters describing the thermal degradation rate. The superior flame-retardancy of CH/PA/TiFormula: see text was originated from the shielding and charring effects of the hybrid MXene with biomass materials containing aromatic rings, phenolic and phosphorous compounds.
Transduction of mechanical forces and chemical signals affect every cell in the human body. Fluid flow in systems such as the lymphatic or circulatory systems modulates not only cell morphology, but ...also gene expression patterns, extracellular matrix protein secretion and cell-cell and cell-matrix adhesions. Similar to the role of mechanical forces in adaptation of tissues, shear fluid flow orchestrates collective behaviours of adherent cells found at the interface between tissues and their fluidic environments. These behaviours range from alignment of endothelial cells in the direction of flow to stem cell lineage commitment. Therefore, it is important to characterize quantitatively fluid interface-dependent cell activity. Common macro-scale techniques, such as the parallel plate flow chamber and vertical-step flow methods that apply fluid-induced stress on adherent cells, offer standardization, repeatability and ease of operation. However, in order to achieve improved control over a cell's microenvironment, additional microscale-based techniques are needed. The use of microfluidics for this has been recognized, but its true potential has emerged only recently with the advent of hybrid systems, offering increased throughput, multicellular interactions, substrate functionalization on 3D geometries, and simultaneous control over chemical and mechanical stimulation. In this review, we discuss recent advances in microfluidic flow systems for adherent cells and elaborate on their suitability to mimic physiologic micromechanical environments subjected to fluid flow. We describe device design considerations in light of ongoing discoveries in mechanobiology and point to future trends of this promising technology.
Crude oil leakage from tankers, offshore platforms, drilling rigs and wells, causing severe pollution to the environment has led to irreversible damage to ocean habitat and inhabitants. It has become ...one of the greatest global environmental concerns which has recently attracted major public awareness. In addition, the contamination of sea and inhabitants. It has significantly harmed the fishing and seafood industry, and even raises health and life issues for millions of human beings. Until now, there is still no viable and practical method to effectively reduce the damage from crude oil spill. This has attracted numerous researchers’ attention. For developing an environmentally friendly and cost-effective polymer absorbent for oil spill cleaning. Recently, among all the efforts, it is proven that biomass aerogel can be used as an outstanding absorbent for oil–water separation, which is a feasible solution for tackling the crude oil issue. In this article, a comprehensive review on the current state-of-art for biomass-based aerogels utilised in the field of oil/water separation is provided. This includes the preparation procedures, fabrication processes, and the categorisation of various types of aerogels. Additionally, the future direction and technological advancement will be discussed in detail.
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•A water-filled impedance tube is design and set up with good accuracy.•High sound absorption coefficient is achieved under normal pressure.•Sound absorption mechanism under both normal and high ...pressures is analysed.
Nanotechnology has been widely used for developing sound absorption materials in air, but studies for underwater applications remain limited. In this study, carboxyl functionalized multi-walled carbon nanotubes (MWCNT-COOH) were added into polydimethylsiloxane (PDMS) with dispersant to enhance the underwater acoustic properties. A water-filled impedance tube was built to determine the underwater sound absorption coefficient in the low frequency range from 1500 Hz to 7000 Hz and under variable hydrostatic pressures. Results demonstrate that pure PDMS is nearly acoustically transparent. With the addition of MWCNT-COOH and under normal pressure (0 MPa), the sound absorption coefficient was marginally improved to 0.3. The coefficient can nonetheless be further increased to above 0.75 with the introduction of both surfactant and MWCNT-COOH. It could be postulated that the trapped micro-voids and uniformly dispersed MWCNT-COOH contributed to the improvement when the pressure is at 0 MPa. Effects of MWCNT-COOH concentrations in a range of 0.1 wt% to 2 wt% were investigated. It was ascertained that the concentrations have only a marginal effect on the sound absorption performance. Tests were also conducted at variable hydrostatic pressure above 0 MPa. Results revealed that underwater sound absorption performance decreased with an increase in the hydrostatic pressure in a range of 0.5 MPa to 1.5 MPa. The drop in performance due the increase of hydrostatic pressure supported the claim that the presence of micro-voids within the material matrix structure contributed to the sound absorption.
Increasing demands in minimization of fire risks and meeting fire safety requirements by polymers require advances in knowledge of flame-retardant materials suitable for use in fire-retardancy ...applications. The present work represents the seminal review of alginate/polymer-based materials as flame retardants. Alginates are suitable for this application as they represent alternatives to petroleum-based polymer feedstocks. The content of the present work is structured into four sections: synthesis and structure, including alginate synthesis and modification by polymeric conjugation; properties, including four-stage mechanism of thermal degradation; applications, including commercial information on alginates and polymers; and flame retardancy, including comprehensive summaries of test methods and published data, discussion of key parameters, eight fire retardancy mechanisms, four char generation mechanisms, and extensive quantitative analysis of polymer char formation. The final section culminates in a first-principles approach to the prediction of quantitative polymer char formation. The goal of the review is to provide guidance for the application of alginates and alginates conjugated with fire-retardant polymers as a new generation flame retardant material.
Greater demands for underwater sound absorption materials have been growing due to the concern about underwater noise control in water. Among the range of existing materials, polymer-based materials ...are increasingly being utilized as underwater sound absorption materials. In this paper, different kinds of polymer-based materials for underwater sound absorption with regards to key factors associated with sound absorption properties, measurements, applications, and mechanisms are reviewed and summarized. Commonly used polymers for underwater sound comprise, in general, interpenetrating polymer networks (IPN), polymer foams, and gradient polymers. To further improve underwater sound absorption performance, different types of inclusions that are introduced into the polymer matrix to transform the polymers as underwater sound absorption materials via air voids, solid inclusions, nanofillers, and phononic crystals are discussed. Challenges for further development of better polymer-based acoustic materials to meet requirements of current and future underwater applications are also presented.
•Key factors and tests of polymer-based underwater sound absorption materials.•Different polymers with or without inclusions for underwater sound absorption.•Mechanisms behind the underwater sound absorption.•Challenges for further improving polymer-based underwater water sound absorption materials.
•An out-of-autoclave way to produce low-void carbon fibre reinforced phenolic resin composites.•The fibre/resin content in carbon fibre reinforced phenolic resin composites can affect the residual ...modulus of composites after oxidation.•ZrO2 nanoparticles can potentially act as catalyst to produce more char yield during the oxidation of carbon fibre reinforced phenolic resin composites.•Possible application in thermal protective structures (TPSs) of aerospace vehicles.
This study reports a vacuum-assisted resin infusion method for achieving low-porosity carbon fibre/phenolic resin composites utilizing a low-viscosity (∼281 cp) phenolic resin enhanced by ZrO2 nanoparticles. The experimental results reveal that this method can yield composites with a low porosity of 8.6 ± 2.5 % and average pore size of 3.8 ± 1.73 μm, demonstrating mechanical properties that show great potential for high-temperature structural applications, such as rocket motor nozzles. Moreover, the resultant composites exhibit distinct advantages over composites produced using other out-of-autoclave and autoclave methods investigated in this study in terms of flexural strength and modulus after oxidation treatment. The vacuum infusion approach retains higher resin content in composites than the autoclave method, leading to increased residual modulus post-oxidation. Furthermore, incorporating ZrO2 nanoparticles in the phenolic matrix has significantly enhanced the residual mass, flexural strength, and flexural modulus of the composites following exposure to oxidation at 1200 °C.
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