The Department of Chemical Engineering is located on Thornton Science Park, a modern expressly-designed site that profits from a recently-completed multi-million pound renovation that has created a state-of-the-art teaching and research facility. The site was home to Shell UK’s exploration and research centre since the 1940s, and its takeover by the University heralded the opportunity to apply its legacy to the continuation of world-class innovation and research in the North West. This collection is licenced under a Creative Commons licence. The collection may be reproduced for non-commerical use and without modification, providing that copyright is acknowledged.

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  • Hydrogen and Combined Heat and Power Production from the Steam Gasification of Plastic Wastes. An Experimental and Modelling Analysis Including Techno-Economic and Environmental Assessment

    Brammer, John; Mozafarian, Mohammadali (University of Chester, 2022-11)
    In this work a modular high temperature (850°C to 1150°C) steam gasification process (DMG®) for production of hydrogen, to be used mainly as a clean fuel in the transport system, and combined heat and power production from mixed unrecyclable plastic wastes is studied which is being developed for commercial production by Powerhouse Energy group (PHE). This includes experiments, process modelling, techno-economic and environmental assessments. Three main scenarios were defined for the process operating conditions which include production of 2 tonnes per day (TPD) hydrogen as the first scenario, the second scenario for maximum conversion of the carbon content of the feedstock to gas products, and the third scenario for the maximum hydrogen production. It should be noted that in the second scenario the maximum conversion of the carbon content of the feedstock may not be necessarily 100% conversion, or it may not be possible in a self-sustained process (in terms of energy). Therefore, this scenario is investigated to identify the possible process conditions and outputs for this scenario. An Aspen Plus model was developed for the process and was further calibrated and validated using experimental data obtained from a pilot-scale unit. The model was used for sensitivity analysis for a commercial unit with 35 TPD feed capacity based on the design capacity of the first commercial unit. The modelling results are used to define the optimum process conditions in each defined scenario. Then, each scenario was defined in the developed model for four process temperatures of 850°C, 950°C, 1050°C, and 1150°C. The results from process modelling including mass and energy balance are used for techno-economic analysis and environmental assessments. In techno-economic analysis, three approaches are considered, including fixed sale prices for all products and by-products, considering electricity sale price to domestic, and non-domestic customers, and performing economic evaluation of the process for all scenarios. In the environmental assessment two alternatives of landfilling and incineration to DMG® are defined and the greenhouse gas (GHG) emissions from each alternative are assessed for the same capacity and a comparison between the alternatives are made. Finally, the optimum process condition and sale strategy for the main products are suggested. Based on the results of the performed analyses, it was concluded that using the DMG® technology for production of hydrogen, electricity and heat can be economically viable and that hydrogen with a competitive sale price in compare with hydrogen produced from the available alternative technologies in the market can be produced. Also, it was concluded that DMG® has less environmental impacts in terms of GHG emissions than those from incineration, and considering the plans for banning landfilling of plastic wastes, DMG® can be a good alternative. The specific results are discussed in the result and discussion section and summarised in the conclusion chapter.
  • Dual-modality UDV-PIV system for measurement of solid-liquid flow in sewage facilities

    Fang, Lide; Liu, Yueyuan; Wang, Shaochong; Zhao, Jixun; Faraj, Yousef; Tian, Mengyuan; Wei, Zihui; University of Chester; Hebei University (Elsevier, 2021-10-19)
    Population growth and global industrialization cause a dramatic increase in the amount of sewage sludge produced annually worldwide from Municipal and Industrial Wastewater treatment. The efficient measurement of sewage, which is a typical solid-liquid two-phase flow, has become an important issue that requires to be urgently addressed. In this study, an improved Ultrasonic Doppler Velocimetry (UDV) is proposed to optimize the probe design and hardware design, which reduces the influence of working frequency and echo reverberation on accuracy and improves the stability of the system. A Doppler peak extraction and superposition method is also put forward to correct the offset of Doppler peak frequency. In this paper, Particle Image Velocimetry (PIV) is used to calibrate the UDV system to modify the measurement model of ultrasonic Doppler liquid-solid two-phase flow, and dynamic experiments are carried out in a vertical steel pipe with inner diameter of 50 mm at different flow conditions. The results show that the accuracy and stability of UDV measurement system are greatly improved, with a maximum relative error of 1.49%.
  • Smart hydrogels with wide visible color tunability

    Wen, Guo-Yu; Zhou, Xing-Long; Tian, Xiao-Yu; Xie, Rui; Ju, Xiao-Jie; Liu, Zhuang; Faraj, Yousef; Wang, Wei; Chu, Liang-Yin; University of Chester; Sichuan University (Springer Nature, 2022-04-01)
    Pigmentary coloration can produce viewing angle-independent uniform colors via light absorption by chromophores. However, due to the limited diversity in the changes of the molecular configuration of chromophores to undergo color change, the existing materials cannot produce a wide range of visible colors with tunable color saturation and transmittance. Herein, we propose a novel strategy to create materials with a wide visible color range and highly tunable color saturation and transmittance. We fabricated a hydrogel with poly (acrylamide-co-dopamine acrylamide) networks swollen with Fe3+-containing glycerol/water in which the covalently crosslinked polyacrylamide backbone with pendant catechols can ensure that the hydrogel maintains a very stable shape. Hydrogels containing adjustable catechol-Fe3+ coordination bonds with flexible light-interacting configuration changes can display a wide range of visible colors based on the complementary color principle. The catechol-Fe3+ complexes can dynamically switch between noncoordinated and mono-, bis- and tris-coordinated states to harvest light energy from a specific wavelength across the whole visible spectrum. Therefore, these hydrogels can be yellow, green, blue, and red, covering the three primary colors. Moreover, color saturation and transmittance can be flexibly manipulated by simply adjusting the Fe3+ content in the hydrogel networks. The versatility of these smart hydrogels has been demonstrated through diverse applications, including optical filters for color regulation and colorimetric sensors for detecting UV light and chemical vapors. This proposed smart hydrogel provides a universal color-switchable platform for the development of multifunctional optical systems such as optical filters, sensors, and detectors.
  • Smart Hydrogel Grating Immunosensors for Highly Selective and Sensitive Detection of Human-IgG

    Zhao, Jia-Jia; Wang, Wei; Wang, Fang; Zhao, Yu; Cai, Quan-Wei; Xie, Rui; Ju, Xiao-Jie; Liu, Zhuang; Faraj, Yousef; Chu, Liang-Yin; et al. (American Chemical Society, 2020-05-08)
    A smart diffraction grating immunosensor based on antigen-responsive hydrogel with enhanced analyte-induced volume changes is developed for highly selective and sensitive detection of human immunoglobulin G (H-IgG). The hydrogel grating contains poly(N-isopropylacrylamide) (PNIPAM) backbones with dual-cross-linking based on the dynamic complexation between pendent goat-anti-human IgG (GAH-IgG) and pendent H-IgG, and the covalent bonding by 4-arm-polyethylene glycol-acrylamide. Upon recognizing free H-IgG in the environment, the pendent GAH-IgG in the hydrogel can form new GAH-IgG/H-IgG complexes with free H-IgG because the binding constant of GAH-IgG to the free H-IgG is much larger than that of GAH-IgG to the pendent H-IgG and thus result in the decomplexation of GAH-IgG/H-IgG complexes with the pendent H-IgG as well as the swelling of hydrogel. The thermo-responsive PNIPAM backbones enable enhancement of H-IgG-responsive volume change of the proposed hydrogel grating via temperature regulation. Moreover, the cross-linker 4-arm-polyethylene glycol-acrylamide provides excellent transparency for the PNIPAM backbones during the volume change, which ensures output of diffracted optical signals with high intensity. With the elaborately designed molecular structures, the hydrogel grating allows highly selective and sensitive detection of [H-IgG] with a detection limit as low as 1.3 × 10–8 M. This work provides a simple and flexible strategy for developing diffraction grating immunosensors based on stimuli-responsive hydrogels for efficient detection of biomarkers.
  • Facile and Scalable Rotation-Based Microfluidics for Controllable Production of Emulsions, Microparticles, and Microfibers

    Su, Yao-Yao; Pan, Da-Wei; Deng, Chuan-Fu; Yang, Shi-Hao; Faraj, Yousef; Xie, Rui; Ju, Xiao-Jie; Liu, Zhuang; Wang, Wei; Chu, Liang-Yin; et al. (American Chemical Society, 2023-03-06)
    A rotation-based microfluidic system with simple device setup and flow manipulation is developed for facile production of controllable emulsion droplets and liquid jets as well as functional microparticles and microfibers. The system consists of a vertically fixed injection tube and a rotating container. This system allows controllable production of single emulsion droplets and single-phase jets with adjustable uniform sizes, and predictable scale-up performance via numbering-up capillary to achieve an enhanced production rate. By flexibly changing the capillary geometry, this system can controllably produce single emulsion droplets with dual-phasic and triphasic morphologies, double emulsion droplets with core–shell and multicore–shell morphologies, and dual-phasic Janus jets. Moreover, this system can controllably fabricate versatile microparticles and microfibers from their droplet and jet templates via fast solidification without microchannel blocking in the open container. This work provides a powerful platform for promoting the wide-scale impact of microfluidics in material science, chemical, and biological fields.
  • Mesoscale regulation of droplet templates to tailor microparticle structures and functions

    Han-Yu Peng, Han-Yu; Wang, Wei; Xie, Rui; Ju, Xiao-Jie; Liu, Zhuang; Faraj, Yousef; Chu, Liang-Yin; University of Chester; Sichuan University (Elsevier, 2019-03-25)
    The hierarchical design of mesoscale structures in droplet templates determines the structure and functionality of the resultant microparticles. In this review, we summarize recent progress on the control of microfluidic emulsion templates for the synthesis of polymeric microparticles with desired functionality and internal structure. We introduce strategies for controlling the morphology and interfacial stability of emulsion templates. These strategies are based on manipulation of the mesoscale structure of amphiphilic molecules and nanoparticles at emulsion-droplet interfaces. We also discuss strategies for controlling the mesoscale structure of microparticles, which involve manipulating the interfacial mass-transfer and chemical reactions during template synthesis. We provide insight on the use of these strategies for the rational design and fabrication of polymeric microparticles with predictable internal structures and functionality at the single-particle level.
  • Measurement and characterization of slurry flow using Electrical Resistance Tomography

    Faraj, Yousef; University of Chester (Woodhead Publishing, 2022-05-13)
    This chapter introduces the measurement, visualization, and characterization of settling slurry flow using Electrical Resistance Tomography (ERT). It starts by presenting the physical mechanisms governing hydraulic transport of solid particles, along with the typical slurry flow patterns in a pipeline. It then explains the ability of ERT for characterization of solid–liquid flow through solids volume fraction measurement, solids axial velocity measurement, and solids flow visualization. By the end of the chapter, the ability of ERT and its utilization for estimation of some parameters related to stratified slurry flow, such as mean granular bed concentration, mean granular bed velocity, the height of granular bed, the height of shear layer and the height of turbulent zone at the upper part of the pipe, are fully discussed. The limitations of ERT in slurry flow measurement and visualization are also highlighted.
  • Novel Pyrolusite-Templated Biochar as an Outstanding Catalyst for Persulfate Activation: Structural Design, Synergistic Effect, and Mechanism

    Feng, Wenwei; Faraj, Yousef; Yan, Yuan; An, Yaoxiao; Xie, Ruzhen; Lai, Bo; University of Chester; Sichuan University (American Chemical Society, 2022-01-18)
    The design of a high-efficiency and ecofriendly persulfate (PS) activator with low cost and superior performance in water decontamination still remains a big challenge. Herein, we report a facile strategy for the synthesis of novel pyrolusite-templated mesoporous catalyst (PMC), and used it as a green PS activator for the outstanding removal of bisphenol A (BPA) in water. The N2 adsorption–desorption curves and SEM-EDS images show that pyrolusite templating can successfully modulate the mesoporous structure of the catalyst; the XRD and XPS spectra indicate that pyrolusite templating renders the catalyst with enriched active sites and faster electron transfer. The mechanism studies suggest that both the radical and nonradical pathway [singlet oxygen (1O2)] contributed to BPA degradation, and 86.81% of the total organic carbon (TOC) of 100 mg/L BPA was removed using merely 0.4 g/L PMC, without detectable metal ion leaching. This work provides a new strategy for the structural design and property adjustment of an efficient persulfate catalyst for green environmental remediation.
  • Perovskite-Based Nanomaterials and Nanocomposites for Photocatalytic Decontamination of Water

    Faraj, Yousef; Xie, Ruzhen; University of Chester; Sichuan University (IntechOpen, 2022-04-21)
    The exploration of functional nanomaterials with superior catalytic activity for practical photocatalytic water decontamination is of significant importance. Perovskite-based nanomaterials, which demonstrate excellent photophysical and catalytic properties, are widely investigated as a class of adaptable materials for the photocatalytic degradation of environmental pollutants. This chapter introduces the recent progresses in using perovskite-based nanocomposites with particular emphasis on the applications for effective photocatalytic degradation of organic pollutants in wastewater. It starts by presenting the general principles and mechanisms governing photocatalytic degradation of organic pollutants in water by perovskite, along with the design criteria for perovskite-based nanocomposites. It then explains various strategies used to prepare perovskite-based nanocomposites with the aim of enhancing their photocatalytic activity. By the end of the chapter, the remaining challenges and perspectives for developing efficient perovskite-based photocatalysts with potential large-scale application are highlighted.
  • Microfluidic emulsification techniques for controllable emulsion production and functional microparticle synthesis

    Wang, Wei; Li, Bing-Yu; Zhang, Mao-Jie; Su, Yao-Yao; Pan, Da-Wei; Liu, Zhuang; Ju, Xiao-Jie; Xie, Rui; Faraj, Yousef; Liang-Yin Chu, Liang-Yin; et al. (Elsevier, 2022-09-17)
    Emulsions play important roles in template synthesis of functional microparticles for myriad fields. The size, shape, composition and structure of emulsion droplets generally determine those features of the resultant microparticles and their functions. Precise control over these features of emulsions is vital to template synthesis of controllable application-oriented microparticles with advanced functions. This review summarizes recent progress on microfluidic emulsification techniques for controllable emulsion production and functional microparticle synthesis. First, versatile microfluidic emulsification techniques for controllable generation of emulsions from simple single emulsions to complex multiple emulsions are introduced. The flexible structural changes of emulsions induced by regulating the mesoscale structures of packed surfactant molecules at the interfaces are discussed. Then, rational synthesis of microparticles with controllable sizes, shapes, compositions, structures and functions from emulsion templates are introduced. The rational design of emulsion templates and interplay between the shape, structure and composition of microparticles to achieve desired functions for applications such as controlled release, water remediation, and catalysis are highlighted. Particularly, interplay between the mesoscale structures of functional components in the emulsion templates and the fine structures and advanced functions of certain microparticles, is discussed. Finally, future development of microfluidics in controllable emulsion production and microparticle synthesis is discussed.
  • Structural optimization and characteristics of a novel single-ended pressure vessel with inside and outside tubes

    Fang, Lide; Han, Bangbang; Lv, Xiaohui; Faraj, Yousef; Wei, Zihui; Li, Xiaoting; University of Chester, Hebei University; National and Local Joint Engineering Research Center for Measuring Instruments and Systems (Elsevier, 2021-08-28)
    A new type of inside and outside tubes differential pressure flowmeter was designed. The throat structure and single-end pressure tapping method is proposed. Three-dimensional numerical simulation is used for structural optimization. The experimental prototype is processed and calibrated in real-time. It was found that the differential pressure values of the new flowmeter was 3.4 times higher and pressure loss ratio only 20% of the original flowmeter in forward flow, while 2.6 times higher and pressure loss ratio only 25% in reverse flow. The sensitivity and energy efficiency of the novel flowmeter is shown to be significantly improved.
  • Velocity distribution of liquid phase at gas-liquid two-phase stratified flow based on particle image velocimetry

    Han, Bangbang; Gao, Qixin; Liu, Xu; Ge, Bin; Faraj, Yousef; Fang, Lide; University of Chester, Hebei University; National and Local Joint Engineering Research Center for Measuring Instruments and Systems (Elsevier, 2023-01-26)
    Horizontal gas-liquid flows are commonly encountered in the production section of the oil and gas industry. To further understand all parameters of the pipe cross-section, this paper use particle image velocimetry to study the circular pipe cross-section liquid velocity distribution rule. Firstly the focus is on the software and hardware combination of image correction system, to solve the influence of different refractive indexes of medium and pipeline curvature caused by image distortion. Secondly, the velocity distribution law of the corrected stratified flow (the range of liquid flow of 0.09-0.18 m3/h, and gas flow range of 0.3-0.7 m3/h) cross-section at different flow points of the pipeline cross-section at x=0 and in the Y direction at the maximum liquid velocity is studied. It is found that these distribution laws are caused by the influence of the interphase force of the gas-liquid interface and the resistance of the pipe wall. The current measurements also produce a valuable data set that can be used to further improve the stratified flow model for gas-liquid flow.
  • Electrical resistance tomography-based multi-modality sensor and drift flux model for measurement of oil-gas-water flow

    Rashed, Sara; Faraj, Yousef; Wang, Mi; Wilkinson, Stephen; University of Chester; University of Leeds (IOP publishing, 2022-06-14)
    This paper proposes a novel method to measure each constituent of an oil-gas-water mixture in a water continuous flow, typically encountered in many processes. It deploys a dual-plane electrical resistance tomography sensor for measuring dispersed phase volume fraction and velocity; a gradiomanometer flow density meter and a drift flux model to estimate slip velocities; with absolute pressure and temperature measurements. These data are fused to estimate constituent volume flow rates. Other commonly used operational parameters can be further derived: Water Cut or Water Liquid Ratio and Gas Volume Fraction. Trials are described for flow rates of water 5-10 m3 h-1; oil 2-10 m3 h-1 and gas 1-15 m3 h-1. The comparative results are included with published data from the Schlumberger Gould Research flow facility. The paper proposes the use of the described configuration for measurement of volume flow rates in oil-gas-water flows with an absolute error of ±10 % within Gas Volume Fraction 9 % - 85 % and Water Liquid Ratio > 45 %.
  • Void fraction measurement method in gas-liquid two-phase stratified flow

    Han, Bangbang; Ge, Bin; Faraj, Yousef; Wang, Xiaojie; Fang, Lide; University of Chester; Hebei University (Society of Petroleum Engineers, 2023-02-06)
    The void fraction is a basic parameter to characterize the two-phase flow. Accurate measurement of its value is of great significance for industrial production. In this study, an optical correction system combined with software and hardware is developed. Stereoscopic particle image velocimetry (SPIV) technology is used to measure the void fraction in gas-liquid two-phase stratified flow. The measurement results are compared with those of two-dimensional particle image velocimetry under the same conditions, and the correction effect appears to be reasonably good. The void fraction value is obtained by the image processing of the corrected image. The accuracy of the measurement results are verified by comparing the experimental liquid phase volumetric flow rate with that measured through a standard flowmeter. Twenty types of void fraction prediction models are evaluated using means absolute relative deviation (MARD), root mean square error (RMSE), and grey correlation analysis methods. The results suggest that the Armand (1946) model has the smallest MARD, RMSE value, the largest correlation degree (Ri) value and the best prediction performance. On this basis, an improved model is proposed by fitting the relationship between void fraction and gas volume holdup.
  • Dietary restriction and ageing: Recent evolutionary perspectives

    Mc Auley, Mark T.; University of Chester (Elsevier, 2022-09-24)
    Dietary restriction (DR) represents one of the most robust interventions for extending lifespan. It is not known how DR increases lifespan. The prevailing evolutionary hypothesis suggests the DR response redirects metabolic resources towards somatic maintenance at the expense of investment in reproduction. Consequently, DR acts as a proximate mechanism which promotes a pro-longevity phenotype. This idea is known as resource reallocation. However, growing findings suggest this paradigm could be incomplete. It has been argued that during DR it is not always possible to identify a trade-off between reproduction and lifespan. It is also suggested the relationship between reproduction and somatic maintenance can be uncoupled by the removal or inclusion of specific nutrients. These findings have created an imperative to re-explore the nexus between DR and evolutionary theory. In this review I will address this evolutionary conundrum. My overarching objectives are fourfold: (1) to outline some of the evidence for and against resource reallocation; (2) to examine recent findings which have necessitated a theoretical re-evaluation of the link between life history theory and DR; (3) to present alternatives to the resource reallocation model; (4) to present emerging variables which potentially influence how DR effects evolutionary trade-offs.
  • Cholesterol transport in blood, lipoproteins, and cholesterol metabolism.

    Mc Auley, Mark T.; Morgan, Amy; University of Chester (Elsevier, 2022-04-26)
    The aim of this chapter is to critically discuss recent work which has focused on the dynamics of cholesterol transport and its intersection with health. Firstly, we provide an overview of the main lipoproteins, and their role in whole-body cholesterol metabolism. We then focus on low-density lipoprotein cholesterol (LDL-C) and high-density lipoprotein cholesterol (HDL-C), paying particular attention to a diverse array of evidence which associates perturbations to these lipoproteins with cardiovascular disease (CVD). Next, we explain how aging and obesity disrupt the biological mechanisms that regulate cholesterol metabolism. Crucially, we reveal the parallels between aging and obesity, underscoring that obesity superimposed on the aging process has the potential to exacerbate the age-related dysregulation of cholesterol metabolism. Following this, we unveil how mathematical modeling can be used to deepen our understanding of cholesterol metabolism. We conclude the chapter by discussing the future of this area; in doing so, we reveal how recent experimental findings could open the way for novel therapeutic approaches which could help maintain optimal blood lipoprotein levels and thus increase health span.
  • A Mathematical Model which Examines Age-Related Stochastic Fluctuations in DNA Maintenance Methylation

    Zagkos, Loukas; Roberts, Jason A.; Mc Auley, Mark T.; University of Chester; Imperial College London (Elsevier, 2021-11-11)
    Due to its complexity and its ubiquitous nature the ageing process remains an enduring biological puzzle. Many molecular mechanisms and biochemical process have become synonymous with ageing. However, recent findings have pinpointed epigenetics as having a key role in ageing and healthspan. In particular age related changes to DNA methylation offer the possibility of monitoring the trajectory of biological ageing and could even be used to predict the onset of diseases such as cancer, Alzheimer's disease and cardiovascular disease. At the molecular level emerging evidence strongly suggests the regulatory processes which govern DNA methylation are subject to intracellular stochasticity. It is challenging to fully understand the impact of stochasticity on DNA methylation levels at the molecular level experimentally. An ideal solution is to use mathematical models to capture the essence of the stochasticity and its outcomes. In this paper we present a novel stochastic model which accounts for specific methylation levels within a gene promoter. Uncertainty of the eventual site-specific methylation levels for different values of methylation age, depending on the initial methylation levels were analysed. Our model predicts the observed bistable levels in CpG islands. In addition, simulations with various levels of noise indicate that uncertainty predominantly spreads through the hypermethylated region of stability, especially for large values of input noise. A key outcome of the model is that CpG islands with high to intermediate methylation levels tend to be more susceptible to dramatic DNA methylation changes due to increasing methylation age.
  • DNA Methylation in Genes Associated with the Evolution of Ageing and Disease: A Critical Review

    Mc Auley, Mark T.; University of Chester (Elsevier, 2021-10-15)
    Ageing is characterised by a physical decline in biological functioning which results in a progressive risk of mortality with time. As a biological phenomenon, it is underpinned by the dysregulation of a myriad of complex processes. Recently, however, ever-increasing evidence has associated epigenetic mechanisms, such as DNA methylation (DNAm) with age-onset pathologies, including cancer, cardiovascular disease, and Alzheimer’s disease. These diseases compromise healthspan. Consequently, there is a medical imperative to understand the link between epigenetic ageing, and healthspan. Evolutionary theory provides a unique way to gain new insights into epigenetic ageing and health. This review will: (1) provide a brief overview of the main evolutionary theories of ageing; (2) discuss recent genetic evidence which has revealed alleles that have pleiotropic effects on fitness at different ages in humans; (3) consider the effects of DNAm on pleiotropic alleles, which are associated with age related disease; (4) discuss how age related DNAm changes resonate with the mutation accumulation, disposable soma and programmed theories of ageing; (5) discuss how DNAm changes associated with caloric restriction intersect with the evolution of ageing; and (6) conclude by discussing how evolutionary theory can be used to inform investigations which quantify age-related DNAm changes which are linked to age onset pathology.
  • Modelling Cholesterol Metabolism and Atherosclerosis

    Mc Auley, Mark T.; University of Chester (Wiley, 2021-12-20)
    Atherosclerotic cardiovascular disease (ASCVD) is the leading cause of morbidity and mortality among Western populations. Many risk factors have been identified for ASCVD; however, elevated low-density lipoprotein cholesterol (LDL-C) remains the gold standard. Cholesterol metabolism at the cellular and whole-body level is maintained by an array of interacting components. These regulatory mechanisms have complex behavior. Likewise, the mechanisms which underpin atherogenesis are nontrivial and multifaceted. To help overcome the challenge of investigating these processes mathematical modeling, which is a core constituent of the systems biology paradigm has played a pivotal role in deciphering their dynamics. In so doing models have revealed new insights about the key drivers of ASCVD. The aim of this review is fourfold; to provide an overview of cholesterol metabolism and atherosclerosis, to briefly introduce mathematical approaches used in this field, to critically discuss models of cholesterol metabolism and atherosclerosis, and to highlight areas where mathematical modeling could help to investigate in the future.
  • The interdependency and co-regulation of the vitamin D and cholesterol metabolism.

    Warren, Tara; McAliister, Roisin; Morgan, Amy; Singh Rai, Taranjit; McGilligan, Victoria; Ennis, Matthew; Page, Christopher; Kelly, Catriona; Peace, Aaron; Corfe, Bernard M.; et al. (MDPI, 2021-08-06)
    Vitamin D and cholesterol metabolism overlap significantly in the pathways that contribute to their biosynthesis. However, our understanding of their independent and co-regulation is limited. Cardiovascular disease is the leading cause of death globally and atherosclerosis, the pathology associated with elevated cholesterol, is the leading cause of cardiovascular disease. It is therefore important to understand vitamin D metabolism as a contributory factor. From the literature, we compile evidence of how these systems interact, relating the understanding of the molecular mechanisms involved to the results from observational studies. We also present the first systems biology pathway map of the joint cholesterol and vitamin D metabolisms made available using the Systems Biology Graphical Notation (SBGN) Markup Language (SBGNML). It is shown that the relationship between vitamin D supplementation, total cholesterol, and LDL-C status, and between latitude, vitamin D, and cholesterol status are consistent with our knowledge of molecular mechanisms. We also highlight the results that cannot be explained with our current knowledge of molecular mechanisms: (i) vitamin D supplementation mitigates the side-effects of statin therapy; (ii) statin therapy does not impact upon vitamin D status; and critically (iii) vitamin D supplementation does not improve cardiovascular outcomes, despite improving cardiovascular risk factors. For (iii), we present a hypothesis, based on observations in the literature, that describes how vitamin D regulates the balance between cellular and plasma cholesterol. Answering these questions will create significant opportunities for advancement in our understanding of cardiovascular health

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