• Rapid, Chemical-Free Generation of Optically Scattering Structures in Poly(ethylene terephthalate) Using a CO2 Laser for Lightweight and Flexible Photovoltaic Applications

      Academic Editor: Yan, Yanfa; Hodgson, Simon D.; Gillett, Alice R. (Hindawi, 2018-12-16)
      Highly light scattering structures have been generated in a poly(ethylene terephthalate) (PET) film using a CO2 laser. The haze, and in some cases the transparency, of the PET films have been improved by varying the processing parameters of the laser (namely, scanning velocity, laser output power, and spacing between processed tracks). When compared with the unprocessed PET, the haze has improved from an average value of 3.26% to a peak of 55.42%, which equates to an absolute improvement of 52.16% or a 17-fold increase. In addition to the optical properties, the surfaces have been characterised using optical microscopy and mapped with an optical profilometer. Key surface parameters that equate to the amount and structure of surface roughness and features have been analysed. The CO2 laser generates microstructures at high speed, without affecting the bulk properties of the material, and is inherently a chemical-free process making it particularly applicable for use in industry, fitting well with the high-throughput, roll to roll processes associated with the production of flexible organic photovoltaic devices.
    • Real-time Geometry-Aware Augmented Reality in Minimally Invasive Surgery

      Chen, Long; Tang, Wen; John, Nigel W.; Bournemouth University; University of Chester (IET, 2017-10-27)
      The potential of Augmented Reality (AR) technology to assist minimally invasive surgeries (MIS) lies in its computational performance and accuracy in dealing with challenging MIS scenes. Even with the latest hardware and software technologies, achieving both real-time and accurate augmented information overlay in MIS is still a formidable task. In this paper, we present a novel real-time AR framework for MIS that achieves interactive geometric aware augmented reality in endoscopic surgery with stereo views. Our framework tracks the movement of the endoscopic camera and simultaneously reconstructs a dense geometric mesh of the MIS scene. The movement of the camera is predicted by minimising the re-projection error to achieve a fast tracking performance, while the 3D mesh is incrementally built by a dense zero mean normalised cross correlation stereo matching method to improve the accuracy of the surface reconstruction. Our proposed system does not require any prior template or pre-operative scan and can infer the geometric information intra-operatively in real-time. With the geometric information available, our proposed AR framework is able to interactively add annotations, localisation of tumours and vessels, and measurement labelling with greater precision and accuracy compared with the state of the art approaches.
    • Real-Time Guidance and Anatomical Information by Image Projection onto Patients

      Edwards, Marc R.; Pop, Serban R.; John, Nigel W.; Ritsos, Panagiotis D.; Avis, Nick J.; University of Chester (Eurographics Association, 2016-09)
      The Image Projection onto Patients (IPoP) system is work in progress intended to assist medical practitioners perform procedures such as biopsies, or provide a novel anatomical education tool, by projecting anatomy and other relevant information from the operating room directly onto a patient’s skin. This approach is not currently used widely in hospitals but has the benefit of providing effective procedure guidance without the practitioner having to look away from the patient. Developmental work towards the alpha-phase of IPoP is presented including tracking methods for tools such as biopsy needles, patient tracking, image registration and problems encountered with the multi-mirror effect.
    • Real-world evaluation of a self-startup SSHI rectifier for piezoelectric vibration energy harvesting

      Du, Sijun; Jia, Yu; Zhao, Chun; Chen, Shao-Tuan; Seshia, Ashwin A.; University of Cambridge; University of Chester (Elsevier, 2017-08-02)
      This paper presents an enhanced SSHI (synchronized switch harvesting on inductor) rectifier with startup circuit and representative environment validation using real world vibration data collected from a tram. Compared to a conventional SSHI rectifier, the proposed rectifier dynamically monitors the working status of the circuit and restarts it when necessary. The proposed rectifier is designed in a 0.35 μm HV CMOS process and its performance is experimentally evaluated. With a 500-second real-world collected vibration data, the conventional and the proposed SSHI rectifiers record average power performance improvements by 9.2× and 22× respectively, compared to a passive full-bridge rectifier. As the startup circuit helps restart the SSHI rectifier several times, it is able to extract energy in an increased excitation range and its average power output performance is 2.4× higher than a conventional SSHI rectifier.
    • Recent Developments and Future Challenges in Medical Mixed Reality

      Chen, Long; Day, Thomas W.; Tang, Wen; John, Nigel W.; Bournemouth University and University of Chester (2017-11-23)
      Mixed Reality (MR) is of increasing interest within technology driven modern medicine but is not yet used in everyday practice. This situation is changing rapidly, however, and this paper explores the emergence of MR technology and the importance of its utility within medical applications. A classification of medical MR has been obtained by applying an unbiased text mining method to a database of 1,403 relevant research papers published over the last two decades. The classification results reveal a taxonomy for the development of medical MR research during this period as well as suggesting future trends. We then use the classification to analyse the technology and applications developed in the last five years. Our objective is to aid researchers to focus on the areas where technology advancements in medical MR are most needed, as well as providing medical practitioners with a useful source of reference.
    • Recombination: Multiply infected spleen cells in HIV patients

      Jung, Andreas; Maier, Reinhard; Vartanian, Jean-Pierre; Bocharov, Gennady; Jung, Volker; Fischer, Ulrike; Meese, Eckart; Wain-Hobson, Simon; Meyerhans, Andreas (Nature Publishing Group, 2002-07-11)
      The genome of the human immunodeficiency virus is highly prone to recombination, although it is not obvious whether recombinants arise infrequently or whether they are constantly being spawned but escape identification because of the massive and rapid turnover of virus particles. Here we use fluorescence in situ hybridization to estimate the number of proviruses harboured by individual splenocytes from two HIV patients, and determine the extent of recombination by sequencing amplified DNA from these cells. We find an average of three or four proviruses per cell and evidence for huge numbers of recombinants and extensive genetic variation. Although this creates problems for phylogenetic analyses, which ignore recombination effects, the intracellular variation may help to broaden immune recognition.
    • Research on the synchronization control strategy for microgrid-connected voltage source inverter

      Cao, Yuanzhi; Hu, Yanting; Hu, Rui; Chen, Jianfei (IEEE, 2015-06-30)
      Microgrid is intended and featured to be able to operate in both grid-connected and islanded mode to ensure high quality and reliable power supply. In order to achieve stable operation of the microgrid-connected voltage source inverter (MVSI) units under paralleled or grid-connected mode, a novel synchronization method based on droop control is proposed in this paper. The difference of phase and amplitude between different MVSI units is detected and is used to calculate the output frequency and amplitude of the MVSI. This method can smooth transfer the MVSI units from standalone mode to paralleled mode. The simulation and experimental results show that the proposed method is effective in achieving paralleled operation of the MVSI units.
    • Reverse microemulsion synthesis of layered gadolinium hydroxide

      Xu, Yadong; Suthar, Jugal; Egbu, Raphael; Weston, Andrew J.; Fogg, Andrew M.; Williams, Gareth R.; University College London; University of Chester (Elsevier, 2017-11-05)
      A reverse microemulsion approach has been explored for the synthesis of layered gadolinium hydroxide (LGdH) nanoparticles in this work. This method uses oleylamine as a multifunctional agent, acting as surfactant, oil phase and base. 1-butanol is additionally used as a co-surfactant. A systematic study of the key reaction parameters was undertaken, including the volume ratio of surfactant (oleylamine) to water, the reaction time, synthesis temperature, and the amount of co-surfactant (1-butanol) added. It proved possible to obtain pristine LGdH materials at temperatures of 120 °C or below with an oleylamine: water ratio of 1:4. Using larger amounts of surfactant or higher temperatures caused the formation of Gd(OH)3, either as the sole product or as a major impurity phase. The LGdH particles produced have sizes of ca. 200 nm, with this size being largely independent of temperature or reaction time. Adjusting the amount of 1-butanol co-surfactant added permits the size to be varied between 200 and 300 nm.
    • A review of organic waste enrichment for inducing palatability of black soldier fly larvae: Wastes to valuable resources

      Raksasat, Ratchaprapa; Lim, Jun Wei; Kiatkittipong, Worapon; Kiatkittipong, Kunlanan; Ho, Yeek Chia; Lam, Man Kee; Font Palma, Carolina; Zaid, Hayyiratul Fatimah Mohd; Cheng, Chin Kui; Universiti Teknologi PETRONAS; Silpakorn University; King Mongkut's Institute of Technology Ladkrabang; University of Chester; Khalifa University
      The increase of annual organic wastes generated worldwide has become a major problem for many countries since the mismanagement could bring about negative effects on the environment besides, being costly for an innocuous disposal. Recently, insect larvae have been investigated to valorize organic wastes. This entomoremediation approach is rising from the ability of the insect larvae to convert organic wastes into its biomass via assimilation process as catapulted by the natural demand to complete its lifecycle. Among the insect species, black soldier fly or Hermetia illucens is widely researched since the larvae can grow in various environments while being saprophagous in nature. Even though black soldier fly larvae (BSFL) can ingest various decay materials, some organic wastes such as sewage sludge or lignocellulosic wastes such as waste coconut endosperm are destitute of decent nutrients that could retard the BSFL growth. Hence, blending with nutrient-rich low-cost substrates such as palm kernel expeller, soybean curd residue, etc. is employed to fortify the nutritional contents of larval feeding substrates prior to administering to the BSFL. Alternatively, microbial fermentation can be adopted to breakdown the lignocellulosic wastes, exuding essential nutrients for growing BSFL. Upon reaching maturity, the BSFL can be harvested to serve as the protein and lipid feedstock. The larval protein can be made into insect meal for farmed animals, whilst the lipid source could be extracted and transesterified into larval biodiesel to cushion the global energy demands. Henceforth, this review presents the influence of various organic wastes introduced to feed BSFL, targeting to reduce wastes and producing biochemicals from mature larvae through entomoremediation. Modification of recalcitrant organic wastes via fermentation processes is also unveiled to ameliorate the BSFL growth. Lastly, the sustainable applications of harvested BSFL biomass are as well covered together with the immediate shortcomings that entail further researches.
    • A Review of Piezoelectric and Magnetostrictive Biosensor Materials for Detection of COVID‐19 and Other Viruses

      Narita, Fumio; Wang, Zhenjin; Kurita, Hiroki; Li, Zhen; Shi, Yu; Jia, Yu; Soutis, Constantinos; Tohoku University; Nanjing University of Aeronautics and Astronautics; University of Chester; Aston University; University of Manchester
      The spread of the severe acute respiratory syndrome coronavirus has changed the lives of people around the world with a huge impact on economies and societies. The development of wearable sensors that can continuously monitor the environment for viruses may become an important research area. Here, the state of the art of research on biosensor materials for virus detection is reviewed. A general description of the principles for virus detection is included, along with a critique of the experimental work dedicated to various virus sensors, and a summary of their detection limitations. The piezoelectric sensors used for the detection of human papilloma, vaccinia, dengue, Ebola, influenza A, human immunodeficiency, and hepatitis B viruses are examined in the first section; then the second part deals with magnetostrictive sensors for the detection of bacterial spores, proteins, and classical swine fever. In addition, progress related to early detection of COVID‐19 (coronavirus disease 2019) is discussed in the final section, where remaining challenges in the field are also identified. It is believed that this review will guide material researchers in their future work of developing smart biosensors, which can further improve detection sensitivity in monitoring currently known and future virus threats.
    • The role of DNA methylation in ageing and cancer

      Morgan, Amy; Davies, Trevor J.; Mc Auley, Mark T.; University of Chester (Cambridge University Press, 2018-04-30)
      The aim of the present review paper is to survey the literature related to DNA methylation, and its association with cancer and ageing. The review will outline the key factors, including diet, which modulate DNA methylation. Our rationale for conducting this review is that ageing and diseases, including cancer, are often accompanied by aberrant DNA methylation, a key epigenetic process, which is crucial to the regulation of gene expression. Significantly, it has been observed that with age and certain disease states, DNA methylation status can become disrupted. For instance, a broad array of cancers are associated with promoter-specific hypermethylation and concomitant gene silencing. This review highlights that hypermethylation, and gene silencing, of the EN1 gene promoter, a crucial homeobox gene, has been detected in various forms of cancer. This has led to this region being proposed as a potential biomarker for diseases such as cancer. We conclude the review by describing a recently developed novel electrochemical method that can be used to quantify the level of methylation within the EN1 promoter and emphasise the growing trend in the use of electrochemical techniques for the detection of aberrant DNA methylation.
    • The role of Mathematical Modelling in understanding Aging

      Mc Auley, Mark T.; Morgan, Amy; Mooney, Kathleen M.; University of Chester, Edgehill University (CRC Press, 2017-10-25)
      Mathematical models have played key roles in developing our understanding of aging. The first pioneering mathematical models evaluated aging from an evolutionary perspective, generating meaningful insights into why aging occurs and laid the foundations for our current understanding of aging. More recently mathematical models have been used to gain a deeper understanding of the intracellular mechanisms associated with intrinsic aging. This chapter will outline what mathematical modelling is, and the advantages it has over more conventional approaches used in biogerontology. The steps involved in assembling a model will also be described and the leading theoretical frameworks underpinning them will be outlined. Moreover, we discuss in detail a variety of aging focused mechanistic mathematical models which have been developed in recent years. The chapter concludes by challenging the community to develop a unified mechanistic mathematical model which can be used to examine aging in a more integrated fashion.
    • Rotary bistable and Parametrically Excited Vibration Energy Harvesting

      Kurmann, Lukas; Jia, Yu; Hoffmann, Daniel; Manoli, Yiannos; Woias, Peter; University of Applied Sciences and Arts Northwestern Switzerland; University of Chester; Hahn-Schickard; University of Freiburg (IOP Publishing, 2016-12-06)
      Parametric resonance is a type of nonlinear vibration phenomenon [1], [2] induced from the periodic modulation of at least one of the system parameters and has the potential to exhibit interesting higher order nonlinear behaviour [3]. Parametrically excited vibration energy harvesters have been previously shown to enhance both the power amplitude [4] and the frequency bandwidth [5] when compared to the conventional direct resonant approach. However, to practically activate the more profitable regions of parametric resonance, additional design mechanisms [6], [7] are required to overcome a critical initiation threshold amplitude. One route is to establish an autoparametric system where external direct excitation is internally coupled to parametric excitation [8]. For a coupled two degrees of freedom (DoF) oscillatory system, principal autoparametric resonance can be achieved when the natural frequency of the first DoF f1 is twice that of the second DoF f2 and the external excitation is in the vicinity of f1. This paper looks at combining rotary and translatory motion and use autoparametric resonance phenomena.
    • Scaling-up ultrasound standing wave enhanced sedimentation filters

      Prest, Jeff E.; Treves Brown, Bernard J.; Fielden, Peter R.; Wilkinson, Stephen J.; Hawkes, Jeremy J.; Lancaster University ; University of Manchester ; Lancaster University ; University of Chester ; University of Manchester (Elsevier, 2014-08-21)
      Particle concentration and filtration is a key stage in a wide range of processing industries and also one that can be present challenges for high throughput, continuous operation. Here we demonstrate some features which increase the efficiency of ultrasound enhanced sedimentation and could enable the technology the potential to be scaled up. In this work, 20 mm piezoelectric plates were used to drive 100 mm high chambers formed from single structural elements. The coherent structural resonances were able to drive particles (yeast cells) in the water to nodes throughout the chamber. Ultrasound enhanced sedimentation was used to demonstrate the efficiency of the system (>99% particle clearance). Sub-wavelength pin protrusions were used for the contacts between the resonant chamber and other elements. The pins provided support and transferred power, replacing glue which is inefficient for power transfer. Filtration energies of ∼4 J/ml of suspension were measured. A calculation of thermal convection indicates that the circulation could disrupt cell alignment in ducts >35 mm high when a 1K temperature gradient is present; we predict higher efficiencies when this maximum height is observed. For the acoustic design, although modelling was minimal before construction, the very simple construction allowed us to form 3D models of the nodal patterns in the fluid and the duct structure. The models were compared with visual observations of particle movement, Chladni figures and scanning laser vibrometer mapping. This demonstrates that nodal planes in the fluid can be controlled by the position of clamping points and that the contacts could be positioned to increase the efficiency and reliability of particle manipulations in standing waves.
    • Second generation PEM fuel cells and the indirect reduction of oxygen

      Davies, Trevor J.; University of Chester (2015-05-21)
      2015 is a breakthrough year for fuel cell technology.
    • Segregation of Anhydrite in Sintered Naturally Occurring Rock Salt

      Swanson, Claudia H.; Boehme, Susanne; Guenster, Jens; University of Chester; Bundesanstalt fuer Materialforschung (Solution Mining Research Institute, 2015-09)
      This study examines the sintering of naturally occurring rock salt in dependence of pressure and temperature as is desired for storage and other applications in saline environments where rock salt is thermodynamically stable and shows a mechanical behavior compatible to the surrounding host material. Rock salt consists mainly of sodium chloride with small impurities of less soluble compounds such as anhydrite, CaSO4 . A special interest in the sintering process of naturally occurring rock salt is the segregation of anhydrite to the grain boundaries between individual sodium chloride crystals. Our study has shown that sintering naturally occurring rock salt at different pressures will influence the segregation of anhydrite. Experiments support a greater segregation of anhydrite resulting from an increased pressure treatment. As the solubility of anhydrite is less than sodium chloride, the sintered samples of naturally occurring rock salt show greater stability towards dissolution than pure sodium chloride.
    • Self-assembled nanostructures in ionic liquids facilitate charge storage at electrified interfaces

      Mao, Xianwen; Brown, Paul; Cervinka, Citrad; Hazell, Gavin; Li, Hua; Ren, Yinying; Chen, Di; Atkin, Rob; Eastoe, Julian; Grillo, Isabelle; et al. (Springer Nature, 2019-08-12)
      Driven by the potential applications of ionic liquids (ILs) in many emerging electrochemical technologies, recent research efforts have been directed at understanding the complex ion ordering in these systems, to uncover novel energy storage mechanisms at IL–electrode interfaces. Here, we discover that surface-active ILs (SAILs), which contain amphiphilic structures inducing self-assembly, exhibit enhanced charge storage performance at electrified surfaces. Unlike conventional non amphiphilic ILs, for which ion distribution is dominated by Coulombic interactions, SAILs exhibit significant and competing van der Waals interactions owing to the non-polar surfactant tails, leading to unusual interfacial ion distributions. We reveal that, at an intermediate degree of electrode polarization, SAILs display optimum performance, because the low-charge-density alkyl tails are effectively excluded from the electrode surfaces, whereas the formation of non-polar domains along the surface suppresses undesired overscreening effects. This work represents a crucial step towards understanding the unique interfacial behaviour and electrochemical properties of amphiphilic liquid systems showing long-range ordering, and offers insights into the design principles for high-energy-density electrolytes based on spontaneous self-assembly behaviour.
    • Self-Dual Codes using Bisymmetric Matrices and Group Rings

      Gildea, Joe; Kaya, Abidin; Korban, Adrian; Tylyshchak, Alexander; University of Chester ; Sampoerna University ; University of Chester: Uzhgorod National University (Elsevier, 2020-08-14)
      In this work, we describe a construction in which we combine together the idea of a bisymmetric matrix and group rings. Applying this construction over the ring F4 + uF4 together with the well known extension and neighbour methods, we construct new self-dual codes of length 68: In particular, we find 41 new codes of length 68 that were not known in the literature before.
    • Self-supervised monocular image depth learning and confidence estimation

      Chen, Long; Tang, Wen; Wan, Tao Ruan; John, Nigel W.; Bournemouth University; University of Bradford; University of Chester
      We present a novel self-supervised framework for monocular image depth learning and confidence estimation. Our framework reduces the amount of ground truth annotation data required for training Convolutional Neural Networks (CNNs), which is often a challenging problem for the fast deployment of CNNs in many computer vision tasks. Our DepthNet adopts a novel fully differential patch-based cost function through the Zero-Mean Normalized Cross Correlation (ZNCC) to take multi-scale patches as matching and learning strategies. This approach greatly increases the accuracy and robustness of the depth learning. Whilst the proposed patch-based cost function naturally provides a 0-to-1 confidence, it is then used to self-supervise the training of a parallel network for confidence map learning and estimation by exploiting the fact that ZNCC is a normalized measure of similarity which can be approximated as the confidence of the depth estimation. Therefore, the proposed corresponding confidence map learning and estimation operate in a self-supervised manner and is a parallel network to the DepthNet. Evaluation on the KITTI depth prediction evaluation dataset and Make3D dataset show that our method outperforms the state-of-the-art results.
    • The sharp interface limit for the stochastic Cahn-Hilliard Equation

      Antonopoulou, Dimitra; Bloemker, Dirk; Karali, Georgia D.; Universiy of Chester (IMS Journals, 2018-02-19)
      We study the two and three dimensional stochastic Cahn-Hilliard equation in the sharp interface limit, where the positive parameter \eps tends to zero, which measures the width of transition layers generated during phase separation. We also couple the noise strength to this parameter. Using formal asymptotic expansions, we identify the limit. In the right scaling we indicate that the solutions of stochastic Cahn-Hilliard converge to a solution of a Hele-Shaw problem with stochastic forcing. In the case when the noise is sufficiently small, we rigorously prove that the limit is a deterministic Hele-Shaw problem. Finally, we discuss which estimates are necessary in order to extend the rigorous result to larger noise strength.