• Determining control parameters for dendritic cell-cytotoxic T lymphocyte interaction

      Ludewig, Burkhard; Krebs, Philippe; Junt, Tobias; Metters, Helen; Ford, Neville J.; Anderson, Roy M.; Bocharov, Gennady; University of Zürich ; University of Zürich ; University of Zürich ; University of Zürich ; University College Chester ; Imperial College, University of London ; Institute of Numerical Mathematics, Russian Academy of Sciences (WILEY-VCH Verlag GmbH & Co. KGaA, 2004-08-05)
      Dendritic cells (DC) are potent immunostimulatory cells facilitating antigen transport to lymphoid tissues and providing efficient stimulation of T cells. A series of experimental studies in mice demonstrated that cytotoxic T lymphocytes (CTL) can be efficiently induced by adoptive transfer of antigen-presenting DC. However, the success of DC-based immunotherapeutic treatment of human cancer, for example, is still limited because the details of the regulation and kinetics of the DC-CTL interaction are not yet completely understood. Using a combination of experimental mouse studies, mathematical modeling, and nonlinear parameter estimation, we analyzed the population dynamics of DC-induced CTL responses. The model integrates a predator-prey-type interaction of DC and CTL with the non-linear compartmental dynamics of T cells. We found that T cell receptor avidity, the half-life of DC, and the rate of CTL-mediated DC-elimination are the major control parameters for optimal DC-induced CTL responses. For induction of high avidity CTL, the number of adoptively transferred DC was of minor importance once a minimal threshold of approximately 200 cells per spleen had been reached. Taken together, our study indicates that the availability of high avidity T cells in the recipient in combination with the optimal application regimen is of prime importance for successful DC-based immunotherapy.
    • A deterministic oscillatory model of microtubule growth and shrinkage for differential actions of short chain fatty acids

      Kilner, Josephine; Corfe, Bernard M.; Mc Auley, Mark T.; Wilkinson, Stephen J.; University of Sheffield; University of Chester (Royal Society of Chemistry, 2015-11-09)
      Short chain fatty acids (SCFA), principally acetate, propionate, butyrate and valerate, are produced in pharmacologically relevant concentrations by the gut microbiome. Investigations indicate that they exert beneficial effects on colon epithelia. There is increasing interest in whether different SCFAs have distinct functions which may be exploited for prevention or treatment of colonic diseases including colorectal cancer (CRC), inflammatory bowel disease and obesity. Based on experimental evidence, we hypothe-sised that odd-chain SCFAs may possess anti-mitotic capabilities in colon cancer cells by disrupting microtubule (MT) structural integrity via dysregulation of b-tubulin isotypes. MT dynamic instability is an essential characteristic of MT cellular activity. We report a minimal deterministic model that takes a novel approach to explore the hypothesised pathway by triggering spontaneous oscillations to represent MT dynamic behaviour. The dynamicity parameters in silico were compared to those reported in vitro.Simulations of untreated and butyrate (even-chain length) treated cells reflected MT behaviour in interphase or untreated control cells. The propionate and valerate (odd-chain length) simulations displayed increased catastrophe frequencies and longer periods of MT-fibre shrinkage. Their enhanced dynamicity wasdissimilar to that observed in mitotic cells, but parallel to that induced by MT-destabilisation treatments.Antimicrotubule drugs act through upward or downward modulation of MT dynamic instability. Our computational modelling suggests that metabolic engineering of the microbiome may facilitate managing CRC risk by predicting outcomes of SCFA treatments in combination with AMDs
    • Developing A High-performance Liquid Chromatography Method for Simultaneous Determination of Loratadine and its Metabolite Desloratadine in Human Plasma.

      Sebaiy, Mahmoud M; Ziedan, Noha I (2019-11-24)
      Allergic diseases are considered among the major burdons of public health with increased prevalence globally. Histamine H1-receptor antagonists are the foremost commonly used drugs in the treatment of allergic disorders. Our target drug is one of this class, loratadine and its biometabolite desloratadine which is also a non sedating H1 receptor antagonist with anti-histaminic action of 2.5 to 4 times greater than loratadine. To develop and validate a novel isocratic reversed-phase high performance liquid chromatography (RP-HPLC) method for rapid and simultaneous separation and determination of loratadine and its metabolite, desloratadine in human plasma. The drug extraction method from plasma was based on protein precipitation technique. The separation was carried out on a Thermo Scientific BDS Hypersil C18 column (5µm, 250 x 4.60 mm) using a mobile phase of MeOH : 0.025M KH2PO4 adjusted to pH 3.50 using orthophosphoric acid (85 : 15, v/v) at ambient temperature. The flow rate was maintained at 1 mL/min and maximum absorption was measured using PDA detector at 248 nm. The retention times of loratadine and desloratadine in plasma samples were recorded to be 4.10 and 5.08 minutes respectively, indicating a short analysis time. Limits of detection were found to be 1.80 and 1.97 ng/mL for loratadine and desloratadine, respectively, showing a high degree of method sensitivity. The method was then validated according to FDA guidelines for the determination of the two analytes in human plasma. The results obtained indicate that the proposed method is rapid, sensitive in the nanogram range, accurate, selective, robust and reproducible compared to other reported methods. [Abstract copyright: Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.]
    • Developing critical insights into artificial intelligence

      Kerins, John (Higher Education Academy, 2005-10)
      This article discusses how to gain insights into artifical intelligence through introducing context, theory, and relevant practical tasks that allow students to gain a deeper understanding into some of the scientific and engineering goals of artifical intelligence.
    • Development in laser peening of advanced ceramic

      Shukla, Pratik; Smith, Graham C.; Waugh, David G.; Lawrence, Jonathan; University of Chester Laser Engineering & Manufacturing Research Group (Shukla, Waugh, Lawrence); University of Chester Department of Natural Sciences (Smith) (SPIE (International Society for Optics and Photonics), 2015-07-01)
      Laser peening is a well-known process applicable to surface treat metals and alloys in various industrial sectors. Research in the area of laser peening of ceramics is still scarce and a complete laser-ceramic interaction is still unreported. This paper focuses on laser peening of SiC ceramics employed for cutting tools, armor plating, dental and biomedical implants, with a view to elucidate the unreported work. A detailed investigation was conducted with 1064nm Nd:YAG ns pulse laser to first understand the surface effects, namely: the topography, hardness, KIc and the microstructure of SiC advanced ceramics. The results showed changes in surface roughness and microstructural modification after laser peening. An increase in surface hardness was found by almost 2 folds, as the diamond footprints and its flaws sizes were considerably reduced, thus, enhancing the resistance of SiC to better withstand mechanical impact. This inherently led to an enhancement in the KIc by about 42%. This is attributed to an induction of compressive residual stress and phase transformation. This work is a first-step towards the development of a 3-dimensional laser peening technique to surface treat many advanced ceramic components. This work has shown that upon tailoring the laser peening parameters may directly control ceramic topography, microstructure, hardness and the KIc. This is useful for increasing the performance of ceramics used for demanding applications particularly where it matters such as in military. Upon successful peening of bullet proof vests could result to higher ballistic strength and resistance against higher sonic velocity, which would not only prevent serious injuries, but could also help to save lives of soldiers on the battle fields.
    • Development of laser peening ceramics

      Shukla, Pratik; Lawrence, Jonathan; Waugh, David G.; University of Chester (2015-03)
    • Device to accurately place Epidural Tuohy needle for Anesthesia Administration

      Vaughan, Neil; Dubey, Venketesh N.; Wee, Michael Y. K.; Isaacs, Richard; Bournemouth University; Poole Hospital NHS Foundation Trust (Copernicus Publications, 2014-01-02)
      The aim of this project is to design two sterile devices for epidural needle insertion which can measure in real time (i) the depth of needle tip during insertion and (ii) interspinous pressure changes through a pressure measurement device as the epidural needle is advanced through the tissue layers. The length measurement device uses a small wireless camera with video processing computer algorithms which can detect and measure the moving needle. The pressure measurement device uses entirely sterile componenets including a pressure transducer to accurately measure syringe saline in mm Hg. The data from these two devices accurately describe a needle insertion allowing comparison or review of insertions. The data was then cross-referenced to pre-measured data from MRI or ultrasound scan to identify how ligemant thickness correlates to our measured depth and pressure data. The developed devices have been tested on a porcine specimen during insertions performed by experienced anaesthetists. We have obtained epidural pressures for each ligament and demonstrated functionality of our devices to measure pressure and depth of epidural needle during insertion. This has not previously been possible to monitor in real-time. The benefits of these devices are (i) to provide an alternative method to identify correct needle placement during the procedure on real patients. (ii) The data describing the speed, depth and pressure during insertion can be used to configure an epidural simulator, simulating the needle insertion procedure. (iii) Our pressure and depth data can be compared to pre-measured MRI and ultrasound to identify previously unknown links between epidural pressure and depth with BMI, obesity and body shapes.
    • The diagnostic analysis of the fault coupling effects in planet bearing

      Xue, Song; Wang, Congsi; Howard, Ian; Lian, Peiyuan; Chen, Gaige; Wang, yan; Yan, Yuefei; Xu, Qian; Shi, Yu; Jia, Yu; et al. (Elsevier, 2019-11-09)
      The purpose of this paper is to investigate the fault coupling effects in the planet bearing as well as the corresponding vibration signatures in the resultant vibration spectrum. In a planetary gear application, the planet bearing can not only spin around the planet gear axis, but also revolve about the sun gear axis and this rotating mechanism poses a big challenge for the diagnostic analysis of the planet bearing vibration spectrum. In addition, the frequency component interaction and overlap phenomenon in the vibration spectrum caused by the fault coupling effect can even worsen the diagnosis results. To further the understanding of the fault coupling effects in a planet bearing, a 34° of freedom planetary gear model with detailed planet bearing model was established to obtain the dynamic response in the presence of various bearing fault scenarios. The method of modelling the bearing distributed faults and localized faults has been introduced in this paper, which can be further incorporated into the planetary gear model to obtain the faulted vibration signal. The “benchmark” method has been adopted to enhance the planet bearing fault impulses in the vibration signals and in total, the amplitude demodulation results from 20 planet bearing fault scenarios have been investigated and analyzed. The coherence estimation over the vibration frequency domain has been proposed as a tool to quantify the fault impact contribution from different fault modes and the results suggested that the outer raceway fault contributes most to the resultant planet bearing vibration spectrum in all the investigated fault scenarios.
    • Diamond-coated ‘black silicon’ as a promising material for high-surface-area electrochemical electrodes and antibacterial surfaces

      May, Paul W.; Clegg, Michael; Silva, T.; Zanin, H.; Fatibello-Filho, O.; Celorrio, V.; Fermin, David; Welch, Colin C.; Hazell, Gavin; Fisher, Leanne E.; et al. (Royal Society of Chemistry, 2016-08-08)
      This report describes a method to fabricate high-surface-area boron-doped diamond (BDD) electrodes using so-called ‘black silicon’ (bSi) as a substrate. This is a synthetic nanostructured material that contains high-aspect-ratio nano-protrusions, such as spikes or needles, on the Si surface produced via plasma etching. We now show that coating a bSi surface composed of 15-μm-high needles conformably with BDD produces a robust electrochemical electrode with high sensitivity and high electroactive area. A clinically relevant demonstration of the efficacy of these electrodes is shown by measuring their sensitivity for detection of dopamine (DA) in the presence of an excess of uric acid (UA). Finally, the nanostructured surface of bSi has recently been found to generate a mechanical bactericidal effect, killing both Gram-negative and Gram-positive bacteria at high rates. We will show that BDD-coated bSi also acts as an effective antibacterial surface, with the added advantage that being diamond-coated it is far more robust and less likely to become damaged than Si.
    • Dielectric and Double Debye Parameters of Artificial Normal Skin and Melanoma

      Yang, Bin; Zhang, Rui; Yang, Ke; AbuAli, Najah A.; Hayajneh, Mohammad; Philpott, Mike; Abbasi, Qammer H.; Alomainy, Akram; University of Chester (Springer, 2019-05-16)
      The aim of this study is to characterise the artificial normal skin and melanoma by testing samples with different fibroblast and metastatic melanoma cell densities using terahertz (THz) time-domain spectroscopy (TDS) attenuated total reflection (ATR) technique. Results show that melanoma samples have higher refractive index and absorption coefficient than artificial normal skin with the same fibroblast density in the frequency range between 0.4 and 1.6 THz, and this contrast increases with frequency. It is primarily because that the melanoma samples have higher water content than artificial normal skin, and the main reason to melanoma containing more water is that tumour cells degrade the contraction of the collagen lattice. In addition, complex refractive index and permittivity of the melanoma samples have larger variations than that of normal skin samples. For example, the refractive index of artificial normal skin at 0.5 THz increases 4.3% while that of melanoma samples increases 8.7% when the cell density rises from 0.1 to 1 M/ml. It indicates that cellular response of fibroblast and melanoma cells to THz radiation is significantly different. Furthermore, the extracted double Debye (DD) model parameters demonstrate that the static permittivity at low frequency and slow relaxation time can be reliable classifiers to differentiate melanoma from healthy skin regardless of the cell density. This study helps understand the complex response of skin tissues to THz radiation and the origin of the contrast between normal skin and cancerous tissues.
    • The diffusion-driven instability and complexity for a single-handed discrete Fisher equation

      Yan, Yubin; Zhang, Guang; Zhang, Ruixuan; University of Chester; Tianjin University of Commerce (Elsevier, 2019-12-19)
      For a reaction diffusion system, it is well known that the diffusion coefficient of the inhibitor must be bigger than that of the activator when the Turing instability is considered. However, the diffusion-driven instability/Turing instability for a single-handed discrete Fisher equation with the Neumann boundary conditions may occur and a series of 2-periodic patterns have been observed. Motivated by these pattern formations, the existence of 2-periodic solutions is established. Naturally, the periodic double and the chaos phenomenon should be considered. To this end, a simplest two elements system will be further discussed, the flip bifurcation theorem will be obtained by computing the center manifold, and the bifurcation diagrams will be simulated by using the shooting method. It proves that the Turing instability and the complexity of dynamical behaviors can be completely driven by the diffusion term. Additionally, those effective methods of numerical simulations are valid for experiments of other patterns, thus, are also beneficial for some application scientists.
    • Discontinuous Galerkin time stepping method for solving linear space fractional partial differential equations

      Liu, Yanmei; Yan, Yubin; Khan, Monzorul; LuLiang University; University of Chester (Elsevier, 2017-01-23)
      In this paper, we consider the discontinuous Galerkin time stepping method for solving the linear space fractional partial differential equations. The space fractional derivatives are defined by using Riesz fractional derivative. The space variable is discretized by means of a Galerkin finite element method and the time variable is discretized by the discontinuous Galerkin method. The approximate solution will be sought as a piecewise polynomial function in $t$ of degree at most $q-1, q \geq 1$, which is not necessarily continuous at the nodes of the defining partition. The error estimates in the fully discrete case are obtained and the numerical examples are given.
    • A discrete mutualism model: analysis and exploration of a financial application

      Roberts, Jason A.; Kavallaris, Nikos I.; Rowntree, Andrew P.; University of Chester (Elsevier, 2019-09-16)
      We perform a stability analysis on a discrete analogue of a known, continuous model of mutualism. We illustrate how the introduction of delays affects the asymptotic stability of the system’s positive nontrivial equilibrium point. In the second part of the paper we explore the insights that the model can provide when it is used in relation to interacting financial markets. We also note the limitations of such an approach.
    • Disrupting folate metabolism reduces the capacity of bacteria in exponential growth to develop persisters to antibiotics

      Morgan, Jasmine; Smith, Matthew; Mc Auley, Mark T.; Salcedo-Sora, J. Enrique; Edge Hill University; Liverpool Hope University; University of Chester (Microbiology Society, 2018-11-24)
      Bacteria can survive high doses of antibiotics through stochastic phenotypic diversification. We present initial evidence that folate metabolism could be involved with the formation of persisters. The aberrant expression of the folate enzyme gene fau seems to reduce the incidence of persisters to antibiotics. Folate-impaired bacteria had a lower generation rate for persisters to the antibiotics ampicillin and ofloxacin. Persister bacteria were detectable from the outset of the exponential growth phase in the complex media. Gene expression analyses tentatively showed distinctive profiles in exponential growth at times when bacteria persisters were observed. Levels of persisters were assessed in bacteria with altered, genetically and pharmacologically, folate metabolism. This work shows that by disrupting folate biosynthesis and usage, bacterial tolerance to antibiotics seems to be diminished. Based on these findings there is a possibility that bacteriostatic antibiotics such as anti-folates could have a role to play in clinical settings where the incidence of antibiotic persisters seems to drive recalcitrant infections.
    • Distributed order equations as boundary value problems

      Ford, Neville J.; Morgado, Maria L.; University of Chester ; University of Tras-os-Montes e Alto Douro (Elsevier, 2012-01-20)
      This preprint discusses the existence and uniqueness of solutions and proposes a numerical method for their approximation in the case where the initial conditions are not known and, instead, some Caputo-type conditions are given away from the origin.
    • Domain wall free polar structure enhanced photodegradation activity in nanoscale ferroelectric BaxSr1-xTiO3

      Wang, Yaqiong; Zhang, Man; Jianguo, Liu; Zhang, Haibin; Li, Feng; Tseng, Chiao-Wei; Yang, Bin; Smith, Graham C.; Zhai, Jiwei; Zhang, Zhen; et al.
      Ferroelectric materials exhibit anomalous behavior due to the presence of domains and domain walls which are related to the spontaneous polarization inherent in the crystal structure. Control of ferroelectric domains and domain walls has been used to enhance device performances in ultrasound, pyroelectric detectors and photovoltaic systems with renewed interest in nanostructuring for energy applications. It is also known that the ferroelectric including domain walls can double photocatalytic rate and increase carrier lifetime from μs to ms[1] However, there remains a lack of understanding on the different contributions of the domain and domain walls to photo-catalytic activities. Herein it is found, by comparing samples of nanostructured BaxSr1 xTiO3 with and without a polar domain, that the material with polar domains has a faster reaction rate (k=0.18 min-1) than the non polar one (k = 0.11 min-1). It is further revealed that the observed enhanced photoactivity of perovskite ferroelectric materials stems from the inherent polarization of the domain instead of domain walls. Here, the new understanding of the underlying physics of materials with a spontaneous dipole opens a door to enhance the performance of light induced energy harvesting systems.
    • DOMestic Energy Systems and Technologies InCubator (DOMESTIC) and indoor air quality of the built environment

      Li, Jinghua; Khalid, Yousaf; Phillips, Gavin J.; University of Chester
      Oral presentation at RMetS Students and Early Career Scientists Conference 2020 on research project DOMESTIC (DOMestic Energy Systems and Technologies InCubator), which aims to build a facility for the demonstration of domestic technologies and design methodologies (i.e. air quality, energy efficiency).
    • Double Bordered Constructions of Self-Dual Codes from Group Rings over Frobenius Rings

      Gildea, Joe; Kaya, Abidin; Taylor, Rhian; Tylyshchak, Alexander; University of Chester; Sampoerna University; Uzhgorod State University
      In this work, we describe a double bordered construction of self-dual codes from group rings. We show that this construction is effective for groups of order 2p where p is odd, over the rings F2 + uF2 and F4 + uF4. We demonstrate the importance of this new construction by finding many new binary self-dual codes of lengths 64, 68 and 80; the new codes and their corresponding weight enumerators are listed in several tables
    • Double-diffusive natural convection in a differentially heated wavy cavity under thermophoresis effect

      Grosan, Teodor; Sheremet, Mikhail A.; Pop, Ioan; Pop, Serban R.; Babes-Bolyai University; Tomsk State University; University of Chester (American Institute of Aeronautics and Astronautics, 2018-03-02)
      A numerical analysis is made for thermophoretic transport of small particles through the convection in a differentially heated square cavity with a wavy wall. The governing gas-particle partial differential equations are solved numerically for some values of the considered parameters to investigate their influence on the flow, heat, and mass transfer patterns. It is found that the effect of thermophoresis can be quite significant in appropriate situations. The number of undualtions can essentially modify the heat transfer rate and fluid flow intensity.
    • A Dufort-Frankel Difference Scheme for Two-Dimensional Sine-Gordon Equation

      Liang, Zongqi; Yan, Yubin; Cai, Guorong; University of Chester (Hindawi Publishing Corporation, 2014-10-29)
      A standard Crank-Nicolson finite-difference scheme and a Dufort-Frankel finite-difference scheme are introduced to solve two-dimensional damped and undamped sine-Gordon equations. The stability and convergence of the numerical methods are considered. To avoid solving the nonlinear system, the predictor-corrector techniques are applied in the numerical methods. Numerical examples are given to show that the numerical results are consistent with the theoretical results.