Chemical Engineering

Objective A series of well-defined diffusion experiments was carried out to determine the effective glucose diffusion coefficient in cell-seeded porous scaffolds to understand the importance of nutrient diffusion in tissue engineering bioreactor. Results Cell growth changed the morphological structure of the scaffolds reducing the effective pore space and inevitably decreased the effective glucose diffusivity in the chosen scaffolds, namely, collagen, poly(L-lactide) and poly(caprolactone) scaffolds from 3.71 x 10-9 m 2 /s to 3.23 x 10-9 m 2 /s, 1.39 x 10-10 m 2 /s to 9.09 x 10-11 m 2 /s and 1.78 x 10-10 m 2 /s to 1.32 x 10-10 m 2 /s, respectively. Conclusions The presence of cells over time during cell culture reduces the mobility of glucose. The results of this study should be possible to use to predict the glucose concentration profiles in thick engineered tissues.

Tissue engineering has evolved into an exciting area of research due to its potential in regenerative medicine. The shortage of organ donors as well as incompatibility between patient and donor pose an alarming concern. This has resulted in an interest in regenerative therapy where the importance of understanding the transport properties of critical nutrients such as glucose in numerous tissue engineering membranes and scaffolds is crucial. This is due to its dependency on successful tissue growth as a measure of potential cure for health issues that cannot be healed using traditional medical treatments. In this regard, the diffusion of glucose in membranes and scaffolds that act as templates to support cell growth must be well grasped. Keeping this in mind, this review paper aims to discuss the glucose diffusivity of these materials. The paper reviews four interconnected issues, namely, (i) the glucose diffusion in tissue engineering materials, (ii) porosity and tortuosity of these...

This paper investigates a supercontinuum generated high power highly nonlinear photonic crystal fiber for medical and optical communication applications. The full vector finite difference method with perfectly matched layer is used as an analysis tool. Numerical simulation results show that it is possible to achieve high nonlinear coefficient, near zero ultra-flattened dispersion, low confinement loss and supercontinuum spectrum with high power. Moreover, numerical results show that short length of the proposed photonic crystal fiber is achieved. The numerical simulation results of supercontinuum generation is conducted by solving the generalized nonlinear Schrödinger equation with the split-step Fourier method. It is observed adequate supercontinuum spectrum that broaden from 960 to 1870 nm by considering center wavelengths of 1.06, 1.31, and 1.55 μm into silica based index guiding photonic crystal fiber. This simulation results prove that the proposed design of a highly nonlinear ...

In the current research, three electrospun polycaprolactone (PCL) scaffolds with different pore morphology induced by changing the electrospinning parameters, spinning time and rate, have been prepared in order to provide a fundamental understanding on the effects pore morphology have on nutrient transport behaviour in hollow fibre membrane bioreactor (HFMB). After determining the porosity of the scaffolds, they were investigated for glucose diffusivity using cell culture media (CCM) and distilled water in a diffusion cell at 37 °C. The scanning electron microscope (SEM) images of the microstructure of the scaffolds were analysed further using ImageJ software to determine the porosity and glucose diffusivity. A Krogh cylinder model was used to determine the glucose transport profile with dimensionless variables within the HFMB. The paper discusses the roles of various dimensionless numbers (e.g., Péclet and Damköhler numbers) and non-dimensional groups of variables (e.g., non-dimens...

Titanium alloys, despite their high strength-to-weight ratio, are considered as difficult-to-machine materials. Their poor machinability is attributed, among other reasons, to the accumulation of intense heat near the cutting edge that leads to brisk tool damage. The tool damage, in turn, causes deterioration of work surface quality, consumption of more energy and hike in machining forces. The paper focuses on application of innovative lubro-cooling approaches and variation in cutting parameters with a fixed material removal rate for the sake of impeding tool damage and improving associated performance measures. Two cryogenic coolants (liquid nitrogen and carbon dioxide snow), minimum quantity of lubrication (micro-lubrication) and hybridization of the two were tested for effective dissipation of heat in face-turning of a commonly used titanium alloy. Additionally, the effects of removing a given volume of the alloy in one and two cutting passes (with a fixed material removal rate) on tool wear, work surface roughness, cutting energy consumption and machining forces were also experimentally investigated. The double-pass approach was found to have performed better regarding surface roughness, cutting energy and machining forces. Hybrid application of liquid nitrogen and microlubrication, carbon dioxide snow, and hybrid application of snow and micro-lubrication yielded the best results regarding tool wear, cutting energy consumption, and work surface roughness, respectively. The solitary application of micro-lubrication yielded significant reduction in the cutting force component.

Hole-making is one of the most important processes of metal shaping domain. Although, drilling is a commonly used approach to cut holes in metallic parts, the process cannot be completed with the cutting action of one drill bit if the work material is hard and diameter of the hole is large. Usually, a drill having diameter equal to the required diameter of the hole is utilized to enlarge a predrilled hole of a smaller diameter. In this work, we have investigated sustainability of using another method of enlarging a pre-drilled hole, namely side and end milling and compared it with the drilling-based approach. The work material used in the study is a high carbon steel, which is heat-treated to two distinct levels of surface hardness. Besides process type and work material hardness, the other two parameters tested in the investigation are cutting speed and depth of hole. A total of 16 experiments were performed to generate data regarding the sustainability measures, namely hole surface roughness, specific cutting energy and tool wear. Process choice (drilling or milling) for hole-enlargement was found to possess a significant effect on all the measured responses. Analyses carried out on the experimental data revealed that although the drillingbased option led to an immensely better surface finish, the milling-based option performed better with respect to the other measures of economic and environmental sustainability.

Ti-6Al-4V, the most commonly used alloy of titanium, possesses excellent mechanical properties and corrosion resistance, which is the prime reason for the continual rise in its industrial demand worldwide. The extraordinary mechanical properties of the alloy are viewed as a hindrance when it comes to its shaping processes, and the process of milling is no exception to it. The generation of intense heat flux around the cutting zones is an established reason of poor machinability of the alloy and unacceptably low sustainability of its machining. The work presented in this paper attempts to enhance sustainability of milling Ti-6Al-4V by investigating the effects of milling orientation, cutter’s helix angle, cutting speed, and the type of cryogenic coolant and lubricant on the sustainability measures, such as tool damage, cutting energy consumption, process cost, milling forces, and work surface roughness. It was found that micro-lubrication is more effective than the two commonly used ...

The successful realization of Industry 4.0 depends much on how coherently the cyber and physical realms are conjoined in cyberphysical systems. In the context of the fourth industrial revolution, research efforts have mostly been channeled toward the cyber domain, whereas the physical domain has received significantly lesser consideration. A physical domain generally comprises material shaping equipment, work material, tools, working medium, sensors, automation technology, and connectivity mechanisms. The article provides a comprehensive review of the published literature to establish the states of readiness of the two most important manufacturing technologies: subtractive and additive and their sustainable merger from the perspective of Industry 4.0. Rich potentials in the four characteristics at the process level: speed, sustainability, agility, and customer centricity and three at the system level: connectivity, data collection, and automation are required for a manufacturing system (physical domain) to be Industry 4.0 compatible. The review establishes that the subtractive manufacturing domain is nearly compatible regarding speed and agility but needs improvements in respect of sustainability and customer centricity. Additive manufacturing, on the other hand, appears strong on agility and customer-centricity fronts but needs amelioration regarding production speed and sustainability. In respect of the system level characteristics, both technologies seem to be compatible regarding automation, whereas significant improvements are required in connectivity and data sensing and collection. For the sake of raising compatibility levels of the manufacturing systems, subtractive-additive amalgamation is scrutinized. The amalgamation, especially in a done-in-one configuration, has, reportedly, succeeded to retain the favorable traits of the two manufacturing technologies, thus, bringing the merger much closer to the Industry 4.0 requirements. Proper process planning and optimal work distribution between the subtractive and additive modes are critical for operating an amalgamated system at high levels of the key characteristics.

Water is a quintessential element for the survival of mankind. Its variety of uses means that it is always in a constant state of demand. The supply of water most primarily comes from large reservoirs of water such as lakes, streams, and the ocean itself. As such, it is good practice to monitor its quality to ensure it is fit for human consumption. Current water quality monitoring is often carried out in traditional labs but is time consuming and prone to inaccuracies. Therefore, this paper aims to investigate the feasibility of implementing an Arduino-based sensor system for water quality monitoring. A simple prototype consisting of a microcontroller and multiple attached sensors was employed to conduct weekly onsite tests at multiple daily intervals. It was found that the system works reliably but is reliant on human assistance and prone to data inaccuracies. The system however, provides a solid foundation for future expansion works of the same category to elevate the system to be...

The idea of growing artificial tissues in bioreactors such as hollow fibre membrane bioreactors (HFMBs) has started years ago and preparation of biocompatible porous membranes and scaffolds has been attempted extensively. There also have been several studies on modelling glucose transport processes in HFMBs. However, there is little information available that discusses specifically the glucose diffusivity across tissue engineering membranes or scaffolds and, importantly, its dependence on the properties of the materials (i.e., membrane and scaffold). Therefore, the objective of this study is to deduce the glucose diffusivity across different membranes. Using Fick's law and a diffusion cell in this study, we have determined glucose diffusion coefficients for two different membranes namely cellulose nitrate (CN) and polyvinylidene fluoride (PVDF). These membranes possessed similar pore size with varying thickness and were saturated with water and cell culture medium (CCM). The diffusion experiments were conducted in a thermostated water bath at either 27 or 37 ± 1°C. It was observed that PVDF membrane with greater thickness has a lower diffusivity than CN membrane when both were saturated in CCM and water at 37°C. From the results, we derive the significance of the decrease of diffusion coefficient with increasing thickness of the membranes.

Application of cryogenic fluids for efficient heat dissipation is gradually becoming part and parcel of titanium machining. Not much research is done to establish the minimum quantity of a cryogenic fluid required to sustain a machining process with respect to a given material removal rate. This article presents an experimental investigation for quantifying the sustainability of milling a commonly used titanium alloy (Ti–6Al–4V) by varying mass flow rates of two kinds of cryogenic coolants at various levels of cutting speed. The three cooling options tested are dry (no coolant), evaporative cryogenic coolant (liquid nitrogen), and throttle cryogenic coolant (compressed carbon dioxide gas). The milling sustainability is quantified in terms of the following metrics: tool damage, fluid cost, specific cutting energy, work surface roughness, and productivity. Dry milling carried out the at the highest level of cutting speed yielded the worst results regarding tool damage and surface roug...

Among the main bio-based polymer for food packaging materials, whey protein isolate (WPI) is one of the biopolymers that have excellent film-forming properties and are environmentally friendly. This study was performed to analyse the effect of various concentrations of bio-based nanocrystalline cellulose (NCC) extracted from pineapple crown leaf (PCL) on the properties of whey protein isolate (WPI) films using the solution casting technique. Six WPI films were fabricated with different loadings of NCC from 0 to 10 % w/v. The resulting films were characterised based on their mechanical, physical, chemical, and thermal properties. The results show that NCC loadings increased the thickness of the resulting films. The transparency of the films decreased at higher NCC loadings. The moisture content and moisture absorption of the films decreased with the presence of the NCC, being lower at higher NCC loadings. The water solubility of the films decreased from 92.2% for the pure WPI to 65.5...

This study develops bio-nano composite gelatin-based edible film (NEF) by combining nanogelatin, cellulose nanocrystal (CNC), and nanopropolis (NP) fillers to improve the resulting film characteristics. The NEF was characterized in terms of thickness, swelling, pH, water content, solubility, vapor and oxygen permeability, mechanical properties, heat resistance, morphology, transparency, and color. The results showed that the thickness and swelling increased significantly, whilst the pH did not significantly differ in each treatment. The water content and the water solubility also showed no significant changes with loadings of both fillers. At the same time, vapor and oxygen permeability decreased with addition of the fillers but were not significantly affected by the loading amounts. The heat resistance properties increased with the filler addition. Tensile strength and Young’s modulus increased for the films loaded with >3% CNC. The elongation at break showed a significant diffe...

Ultra-low-pressure membrane (ULPM) filtration has emerged as a promising decentralized water and wastewater treatment method. It has been proven effective in long-term filtration under stable flux without requiring physical or chemical cleaning, despite operating at considerably lower flux. The use of ultra-low pressure, often simply by hydrostatic force (often called gravity-driven membrane (GDM) filtration), makes it fall into the uncharted territory of common pressure-driven membrane filtration. The applied polymeric membrane is sensitive to compaction, wetting, and fouling. This paper reviews recent studies on membrane compaction, wetting, and fouling. The scope of this review includes studies on those phenomena in the ULPM and how they affect the overall performance of the system. The performance of GDM systems for water and wastewater treatment is also evaluated. Finally, perspectives on the future research direction of ULPM filtration are also detailed.

Tissue damage and organ failure are major problems that many people face worldwide. Most of them benefit from treatment related to modern technology’s tissue regeneration process. Tissue engineering is one of the booming fields widely used to replace damaged tissue. Scaffold is a base material in which cells and growth factors are embedded to construct a substitute tissue. Various materials have been used to develop scaffolds. Bio-based natural materials are biocompatible, safe, and do not release toxic compounds during biodegradation. Therefore, it is highly recommendable to fabricate scaffolds using such materials. To date, there have been no singular materials that fulfill all the features of the scaffold. Hence, combining two or more materials is encouraged to obtain the desired characteristics. To design a reliable scaffold by combining different materials, there is a need to choose a good fabrication technique. In this review article, the bio-based natural materials and fine f...

Membrane fouling deteriorates membrane filtration performances. Hence, mitigating membrane fouling is the key factor in sustaining the membrane process, particularly when treating fouling-prone feed, such as oil/water emulsions. The use of spacers has been expanded in the membrane module system, including for membrane fouling control. This study proposed a rotating spacer system to ameliorate membrane fouling issues when treating an oil/water emulsion. The system’s effectiveness was assessed by investigating the effect of rotating speed and membrane-to-disk gap on the hydraulic performance and the energy input and through computational fluid dynamics (CFD) simulation. The results showed that the newly developed rotary spacer system was effective and energy-efficient for fouling control. The CFD simulation results proved that the spacer rotations induced secondary flow near the membrane surface and imposed shear rate and lift force to exert fouling control. Increasing the rotation sp...

Organic waste management is a major global challenge. It accounts for a significant portion of waste that ends up in landfills, where it gradually decomposes and emits methane, a harmful greenhouse gas. Composting is an effective method for potentially solving the problem by converting organic waste into valuable compost. Despite many studies focusing on the composting process, no study has reviewed the technological advancements in the composting fields from the perspective of patents. This review paper begins with background information on the composting process, specifically important factors affecting the process, problems associated with it, and the available technologies to facilitate the process. Different technologies are discussed, ranging from manual to automated methods. Subsequently, 457 patents are selected, classified into different categories, and reviewed in detail, providing a patent technology landscape of composting technology. Automatic composters are more promin...

Ankle sprains are among the most prevalent musculoskeletal system injuries. Prevention of ankle sprains is important, given the frequency of occurrence of an ankle sprain, the risk of reinjury, and its long-term effects. A systematic patent review using the World Intellectual Property Organization (WIPO)’s PATENTSCOPE database has been performed to study the current development of ankle sprain prevention methods. Using the PRISMA statement as a basis, a total of 426 patent documents have been selected for review, consisting of 150 granted patents and 276 patent applications. In the past decade, China and the United States of America (43% and 29% of the patent applications, respectively) have shown great interest in developing ankle sprain prevention methods. Approximately 49% (or 74) of the patents from the 150 granted are associated with braces, 46% (or 68) are related to orthosis, 3% (or 5) are related to tape, and the remaining 2% (or 3) are associated with other types of ankle s...