• Preparation, Characterisation and Measurement of the in vitro Cytotoxicity of Mesoporous Silica Nanoparticles Loaded with Cytotoxic Pt(II) Oxadiazoline Complexes

      Wagner, Gabriele; Herrmann, Rudolf; Department of Natural Sciences, University of Chester, Thornton Science Park, Pool Lane, Ince, Chester, CH2 4NU, UK, and Institute of Physics, University of Augsburg, Universitätsstr. 1, D-86135 Augsburg, Germany. (World Academy of Science, Engineering and Technology, 2016-03-07)
      Cytotoxic platinum compounds play a major role in the chemotherapy of a large number of human cancers. However, due to the severe side effects for the patient and other problems associated with their use, there is a need for the development of more efficient drugs and new methods for their selective delivery to the tumours. One way to achieve the latter could be in the use of nanoparticular carrier materials that can adsorb or chemically bind the drug. In the cell, the drug is supposed to be slowly released, either by physical desorption or by dissolution of the particle framework. Ideally, the cytotoxic properties of the platinum drug unfold only then, in the cancer cell and over a longer period of time due to the gradual release. In this paper, we report on our first steps in this direction. The binding properties of a series of cytotoxic Pt(II) oxadiazoline compounds to mesoporous silica particles has been studied by NMR and UV/vis spectroscopy. High loadings were achieved when the Pt(II) compound was relatively polar, and has been dissolved in a relatively unpolar solvent before the silica was added. Typically, 6-10 hours were required for complete equilibration, suggesting the adsorption did not only occur to the outer surface but also to the interior of the pores. The untreated and Pt(II) loaded particles were characterised by C,H,N combustion analysis, BET/BJH nitrogen sorption, electron microscopy (REM and TEM) and EDX. With the latter methods we were able to demonstrate the homogenous distribution of the Pt(II) compound on and in the silica particles, and no Pt(II) bulk precipitate had formed. The in vitro cytotoxicity in a human cancer cell line (HeLa) has been determined for one of the new platinum compounds adsorbed to mesoporous silica particles of different size, and compared with the corresponding compound in solution. The IC50 data are similar in all cases, suggesting that the release of the Pt(II) compound was relatively fast and possibly occurred before the particles reached the cells. Overall, the platinum drug is chemically stable on silica and retained its activity upon prolonged storage.
    • Probing NaCl hydrate formation from aqueous solutions by Terahertz Time-Domain Spectroscopy

      Yang, Bin; University of Chester
      The cooling-induced formation of hydrate in aqueous NaCl solutions was probed using terahertz time-domain spectroscopy (THz-TDS). It was found that the NaCl hydrate formation is accompanied with emergence of four new absorption peaks at 1.60, 2.43, 3.34 and 3.78 THz. Combining the X-ray diffraction measurement with the solid-state based density functional theory (DFT) calculations, we assign the observed terahertz absorption peaks to the vibrational modes of the formed NaCl⋅2H2O hydrate during cooling. This work dedicates THz-TDS based analysis great potential in studying ionic hydrate and the newly revealed collective vibrational modes could be the sensitive indicators to achieve quantitative analysis in phase transitions and lattice dynamics.
    • Process simulation and thermodynamic analysis of a micro turbine with post-combustion CO2 capture and exhaust gas recirculation

      Ali, Usman; Best, Thom; Finney, Karen N.; Font Palma, Carolina; Hughes, Kevin J.; Ingham, Derek B.; Pourkashanian, Mohamed; University of Leeds (Elsevier, 2014-12-31)
      With the effects of the emissions from power plants causing global climate change, the trend towards lower emission systems such as natural gas power plant is increasing. In this paper a Turbec T100 micro gas turbine is studied. The system is assessed thermodynamically using a steady-state model; model results of its alteration with exhaust gas recirculation (EGR) are presented in this paper. The process simulation with EGR offers a useful assessment when integrated with post-combustion CO2 capture. The EGR model results in the enrichment of the CO2 which decrease the energy demand of the CO2 capture system.
    • Production of Biomethane from Agricultural Waste Using a Cryogenic Carbon Capture Process

      Font Palma, Carolina; Lychnos, George; Willson, Paul; University of Chester; PMW Technology Limited (Energy Proceedings, 2019)
      This paper evaluates a novel cryogenic carbon capture process to upgrade biogas produced from agricultural waste. The A3C cryogenic process offers simplicity and compactness with lower capital and operating costs compared to many alternative processes. The work addresses potential technical issues presented by trace contaminants in the raw biogas including hydrogen sulphide, organics and siloxanes. It is found that the A3C process offers high CO2 removal with minimal biomethane losses while requiring simple raw gas treatment.
    • Programmable logic controllers and Direct digital controls in Buildings

      Khalid, Yousaf; University of Chester (2018-09-30)
      The concept of programmable logic controller (PLC) originated over the last century that has revolutionised the industrial sector. In the last few decades PLC in the form of DDC has been commonly used in Building Energy Management Systems (BEMS). The contribution of this work is to analyse PLC/DDC role in the ongoing BEMS advancements in the building sector. Currently DDC are not understood by building design and simulation engineers who assess the controllability of the building in practice. This paper would enhance the understanding of integrating DDC in buildings and influence creation of better modelling and simulation tools for assessing their impact on energy performance in practice.
    • Promises and Challenges of Growing Microalgae in Wastewater

      Osundeko, Olumayowa; Ansolia, Preeti; Kumar Gupta, Sanjay; Bag, Pushan; Bajhaiya, Amit K.; University of Manchester (Springer, 2019-01-22)
      Microalgae have been theoretically described as a sustainable feedstock for biofuel production. However, there are still some concerns and obstacles that need to be overcome in order to translate the theoretical promise into commercial and economic success. These obstacles include a high requirement for nutrients and sustainable water source and the identification of affordable cultivation conditions. It has been suggested that growing microalgae in wastewater can potentially offset some of these obstacles. Microalgae can perform a dual role for remediation of nutrient pollutants and biomass production when grown in wastewater. However, there are huge challenges to overcome before this route can be exploited in an economically and environmentally sustainable manner. In the present chapter, the potentials and challenges of growing microalgae in wastewater and its future implications are discussed in detail.
    • A promising laser nitriding method for the design of next generation orthopaedic implants: Cytotoxicity and antibacterial performance of titanium nitride (TiN) wear nano-particles, and enhanced wear properties of laser-nitrided Ti6Al4V surfaces

      Chan, Chi Wai; Quinn, James; Hussain, Issam; Carson, Louise; Smith, Graham; Lee, Seunghwan; Queen's University Belfast; University of Lincoln; University of Chester; Technical University of Denmark
      In this study, fibre laser nitriding in open air was applied to the Ti6Al4V alloy in order to improve the wear resistance, thus minimising the generation of wear debris from the surfaces for load-bearing applications. The recent technological advancement to perform the laser nitriding process in open air allows the opportunity to surface-harden any curved and/or specific areas in the hip implants. The laser nitriding process was modulated between the pulsed mode and continuous wave (CW) mode by varying the duty cycle between 60% (pulsed) and 100% (CW). Our experimental investigations were divided into two stages in sequential order: Firstly, to create crack-free, homogenous and golden laser-nitrided surfaces by the proper selection of duty cycle. Secondly, it was to analyse the properties (both physical and chemical) of the wear debris as well as to evaluate their cytotoxicity and antibacterial performance. The laser-nitrided surfaces were characterised and tested using a variety of techniques, incl. optical microscopy, SEM-EDX, XRD, surface roughness and Vickers hardness measurements, as well as tribological tests (i.e. ball-on-disk wear tests and DLS). The wear debris from the laser-nitrided surfaces (collected in the wear tests) were analysed using TEM, XPS and SEM-EDX. Their toxicity was evaluated using in-vitro cell culture with macrophages at two time points (24 h and 48 h). The antibacterial performance was tested in vitro against two of the most commonly implicated pathogens in orthopaedic infection, namely Staphylococcus aureus and Escherichia coli for 24 h. Our findings indicated that the wear resistance of the surfaces after laser nitriding was significantly improved and the amount of wear debris generated was also significantly reduced. The wear particles from the laser-nitrided surfaces were in the nano-sized scale range (0.01 µm to 0.04 µm or 10 nm to 40 nm). They were found to be less toxic towards RAW264.7 macrophages, yet display antimicrobial properties against Staphylococcus aureus, when compared with the larger particles (1.5 µm in size) from the untreated surfaces. It is envisioned that successful fabrication of the non-toxic and highly wear-resistant TiN layer in Ti6Al4V using the open-air laser nitriding technique can enable progress towards the development of metal-on-metal (MoM) hip implants fully made of Ti-based alloys
    • Prospects for petcoke utilization with CO 2 capture in Mexico

      Font Palma, Carolina; Gonzalez Diaz, Abigail; University of Chester; Instituto Nacional de Electricidad y Energías Limpias (INEEL) (Elsevier, 2018-01-31)
      This paper evaluates the introduction of carbon capture and storage (CCS) to Mexico. The gasification technology is presented as a potential alternative to be applied into refinery plants due to high petcoke production. Although economic aspects, such as fuel price and selling CO2, are important in the selection of CCS alternatives, there are other limitations, i.e. water availability and space. In March 2014, Mexico launched its CCS technological roadmap. However, an evaluation of the installation of new CO2-capture ready power plants was not considered. For that reason, this study could be useful to create a technology roadmap that includes the design of CO2 capture plants into refineries and how they will have to operate for CO2 emissions reduction, and taking advantage that most of refineries and petrochemical plants are close to oil fields for enhanced oil recovery (EOR). Integrated gasification combined cycle (IGCC) with CCS was chosen in this paper for power generation using petcoke as feedstock. The emissions of CO2 in kg/kWh could be reduced by 68%.
    • Q-V droop control using fuzzy logic and reciprocal characteristic

      Wang, Lu; Hu, Yanting; Chen, Zhe; Glyndwr University; Aalborg University (Engineering and Technology Publishing, 2014-01-01)
      Today, the conventional power system is facing some global environmental problems, which is leading to a new trend of power grid by using “green and clear” energy sources. As the platform of smart grid technology, the microgrid associated with distributed energy resources (DERs) may provide electric power at distributed voltage level, which not only is an autonomous system, but also can be connected to the main grid. To improve the stability and controllability of the power grid, this paper presents an improved Q-V droop control strategy using fuzzy logic controller and reciprocal characteristic. Matlab/Simulink is used for analysing the performance of system. The feasibility of the improved droop control strategy has been verified and discussed. The results demonstrate the improved Q-V droop control strategy could have good effects in grid-connected and islanded mode, and during operation mode transitions.
    • Quadruple Bordered Constructions of Self-Dual Codes from Group Rings

      Dougherty, Steven; Gildea, Joe; Kaya, Abidin; University of Scranton; University of Chester; Sampoerna University (Springer Verlag, 2019-07-05)
      In this paper, we introduce a new bordered construction for self-dual codes using group rings. We consider constructions over the binary field, the family of rings Rk and the ring F4 + uF4. We use groups of order 4, 12 and 20. We construct some extremal self-dual codes and non-extremal self-dual codes of length 16, 32, 48, 64 and 68. In particular, we construct 33 new extremal self-dual codes of length 68.
    • Qualitative behaviour of numerical approximations to Volterra integro-differential equations

      Song, Yihong; Baker, Christopher T. H.; Suzhou University ; University College Chester (Elsevier, 2004-11-01)
      This article investigates the qualitative behaviour of numerical approximations to a nonlinear Volterra integro-differential equation with unbounded delay.
    • Quality Mapping of Offset Lithographic Printed Antenna Substrates and Electrodes by Millimeter-Wave Imaging

      Zhang, Jiao; Tang, Jianhua; Sun, Wenfeng; Zhang, Yan; Yang, Bin; Wang, Xinke; University of Chester (MDPI, 2019-06-14)
      Offset lithographic printed flexible antenna substrate boards and electrodes have attracted much attention recently due to the boost of flexible electronics. Unmanned quality inspection of these printed substrate boards and electrodes demands high-speed, large-scale and nondestructive methods, which is highly desired for manufacturing industries. The work here demonstrates two kinds of millimeter (mm)-wave imaging technologies for the quality (surface uniformity and functionality parameters) inspection of printed silver substrates and electrodes on paper and thin polyethylene film, respectively. One technology is a mm-wave line scanner system and the other is a terahertz-time domain spectroscopy-based charge-coupled device (CCD) imaging system. The former shows the ability of detecting transmitted mm-wave amplitude signals only; its detection is fast in a second time scale and the system shows great potential for the inspection of large-area printed surface uniformity. The latter technology achieves high spatial resolution images of up to hundreds of micrometers at the cost of increased inspection time, in a time scale of tens of seconds. With the exception of absorption rate information, the latter technology offers additional phase information, which can be used to work out 2D permittivity distribution. Moreover, its uniformity is vital for the antenna performance. Additionally, the results demonstrate that compression rolling treatment significantly improves the uniformity of printed silver surfaces and enhances the substrate’s permittivity values.
    • Quality-Control of UV offset Lithographicaly Printed Electronic-Ink by THz Technology

      Zeng, Yang; Donnan, Robert S.; Edwards, Marc R.; Yang, Bin; University of Chester (IEEE Conference Publications, 2017-10-16)
      In this paper, a novel quality-monitor method of inkjet-printed electronics based on terahertz (THz) sensing is presented. Specifically, two different approaches, namely THz reflection spectroscopy and THz near-field scanning, are proposed.
    • Quantification of the pressures generated during insertion of an epidural needle in labouring women of varying body mass indices

      Wee, M. Y. K.; Isaacs, R. A.; Vaughan, Neil; Dubey, V. N.; Parker, B.; University of Chester; Bournemouth University; Poole Hospital NHS Trust; West Hertfordshire NHS Trust; Southampton University Hospital (Heighten Science Publications, 2017-12-01)
      Objective: The primary aim of this study was to measure pressure generated on a Tuohy needle during the epidural procedure in labouring women of varying body mass indices (BMI) with a view of utilising the data for the future development of a high fi delity epidural simulator. High-fi delity epidural simulators have a role in improving training and safety but current simulators lack a realistic experience and can be improved. Methods: This study was approved by the National Research Ethics Service Committee South Central, Portsmouth (REC reference 11/SC/0196). After informed consent epidural needle insertion pressure was measured using a Portex 16-gauge Tuohy needle, loss-of-resistance syringe, a three-way tap, pressure transducer and a custom-designed wireless transmitter. This was performed in four groups of labouring women, stratified according to BMI kg/m2: 18-24.9; 25-34.9; 35-44.9 and >=45. One-way ANOVA was used to compare difference in needle insertion pressure between the BMI groups. A paired t-test was performed between BMI group 18-24.9 and the three other BMI groups. Ultrasound images of the lumbar spine were undertaken prior to the epidural procedure and lumbar magnetic resonance imaging (MRI) was performed within 72h post-delivery. These images will be used in the development of a high fi delity epidural simulator. Results: The mean epidural needle insertion pressure of labouring women with BMI 18-24.9 was 461mmHg; BMI 25-34.9 was 430mmHg; BMI 35-44.9 was 415mmHg and BMI >=45 was 376mmHg, (p=0.52). Conclusion: Although statistically insignifi cant, the study did show a decreasing trend of epidural insertion pressure with increasing body mass indices.
    • Quenching solutions of a stochastic parabolic problem arising in electrostatic MEMS control

      Kavallaris, Nikos I.; University of Chester (Wiley, 2016-09-15)
      In the current paper, we consider a stochastic parabolic equation which actually serves as a mathematical model describing the operation of an electrostatic actuated micro-electro-mechanical system (MEMS). We first present the derivation of the mathematical model. Then after establishing the local well-posedeness of the problem we investigate under which circumstances a {\it finite-time quenching} for this SPDE, corresponding to the mechanical phenomenon of {\it touching down}, occurs. For that purpose the Kaplan's eigenfunction method adapted in the context of SPDES is employed.
    • 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.