Now showing items 46-65 of 624

• #### Bacillus Spores and Their Relevant Chemicals Studied by Terahertz Time Domain Spectroscopy

Terahertz Time Domain Spectroscopy has been used to investigate 0.2 to 2.2 terahertz (THz) transmission responses of Bacillus spores and their related chemical components. Whilst no THz signatures could be clearly associated with either sporulated cells or their chief chemical components, differing degrees of signal attenuation and frequency-dependent light scattering were observed depending on spore composition and culture media. The observed monotonic increase in absorption by spores over this THz spectral domain is mainly from Mie scattering and also from remnant water bound to the spores.
• #### A barrier and techno-economic analysis of small-scale bCHP (biomass combined heat and power) schemes in the UK.

bCHP (Biomass combined heat and power) systems are highly efficient at smaller-scales when a significant proportion of the heat produced can be effectively utilised for hot water, space heating or industrial heating purposes. However, there are many barriers to project development and this has greatly inhibited deployment in the UK. Project viability is highly subjective to changes in policy, regulation, the finance market and the low cost fossil fuel incumbent. The paper reviews the barriers to small-scale bCHP project development in the UK along with a case study of a failed 1.5 MWel bCHP scheme. The paper offers possible explanations for the project’s failure and suggests adaptations to improve the project resilience. Analysis of the project’s: capital structuring; contract length and bankability; feedstock type and price uncertainty, and; plant oversizing highlight the negative impact of the existing project barriers on project development. The research paper concludes with a discussion on the effects of these barriers on the case study project and this industry more generally. A greater understanding of the techno-economic effects of some barriers for small-scale bCHP schemes is demonstrated within this paper, along with some methods for improving the attractiveness and resilience of projects of this kind.
• #### Benchmarking of a micro gas turbine model integrated with post-combustion CO2 capture

The deployment of post-combustion CO2 capture on large-scale gas-fired power plants is currently progressing, hence the integration of the power and capture plants requires a good understanding of operational requirements and limitations to support this effort. This article aims to assist research in this area, by studying a micro gas turbine (MGT) integrated with an amine-based post-combustion CO2 capture unit. Both processes were simulated using two different software tools –IPSEpro and Aspen Hysys, and validated against experimental tests. The two MGT models were benchmarked at the nominal condition, and then extended to part-loads (50 and 80 kWe), prior to their integration with the capture plant at flue gas CO2 concentrations between 5 and 10 mol%. Further, the performance of the MGT and capture plant when gas turbine exhaust gases were recirculated was assessed. Exhaust gas recirculation increases the CO2 concentration, and reduces the exhaust gas flowrate and specific reboiler duty. The benchmarking of the two models revealed that the IPSEpro model can be easily adapted to new MGT cycle modifications since turbine temperatures and rotational speeds respond to reaching temperature limits; whilst a detailed rate-based approach for the capture plant in Hysys resulted in closely aligned simulation results with experimental data.

• #### Bifurcations in numerical methods for volterra integro-differential equations

This article discusses changes in bifurcations in the solutions. It extends the work of Brunner and Lambert and Matthys to consider other bifurcations.
• #### Bioinspired bactericidal surfaces with polymer nanocone arrays

Infections resulting from bacterial biofilm formation on the surface of medical devices are challenging to treat and can cause significant patient morbidity. Recently, it has become apparent that regulation of surface nanotopography can render surfaces bactericidal. In this study, poly(ethylene terephthalate) nanocone arrays are generated through a polystyrene nanosphere-mask colloidal lithographic process. It is shown that modification of the mask diameter leads to a direct modification of centre-to-centre spacing between nanocones. By altering the oxygen plasma etching time it is possible to modify the height, tip width and base diameter of the individual nanocone features. The bactericidal activity of the nanocone arrays was investigated against Escherichia coli and Klebsiella pneumoniae. It is shown that surfaces with the most densely populated nanocone arrays (center-to-center spacing of 200 nm), higher aspect ratios (>3) and tip widths <20 nm kill the highest percentage of bacteria (∼30%).

• #### Blending low-order stabilised finite element methods: a positivity preserving local projection method for the convection-diffusion equation

In this work we propose a nonlinear blending of two low-order stabilisation mechanisms for the convection–diffusion equation. The motivation for this approach is to preserve monotonicity without sacrificing accuracy for smooth solutions. The approach is to blend a first-order artificial diffusion method, which will be active only in the vicinity of layers and extrema, with an optimal order local projection stabilisation method that will be active on the smooth regions of the solution. We prove existence of discrete solutions, as well as convergence, under appropriate assumptions on the nonlinear terms, and on the exact solution. Numerical examples show that the discrete solution produced by this method remains within the bounds given by the continuous maximum principle, while the layers are not smeared significantly.
• #### Bordered Constructions of Self-Dual Codes from Group Rings and New Extremal Binary Self-Dual Codes

We introduce a bordered construction over group rings for self-dual codes. We apply the constructions over the binary field and the ring $\F_2+u\F_2$, using groups of orders 9, 15, 21, 25, 27, 33 and 35 to find extremal binary self-dual codes of lengths 20, 32, 40, 44, 52, 56, 64, 68, 88 and best known binary self-dual codes of length 72. In particular we obtain 41 new binary extremal self-dual codes of length 68 from groups of orders 15 and 33 using neighboring and extensions. All the numerical results are tabulated throughout the paper.
• #### Boundedness and stability of solutions to difference equations

This article discusses the qualitative behaviour of solutions to difference equations, focusing on boundedness and stability of solutions. Examples demonstrate how the use of Lipschintz constants can provide insights into the qualitative behaviour of solutions to some nonlinear problems.
• #### Boundness and stability of differential equations

This paper discusses the qualitative behaviour of solutions to difference equations, focusing on boundedness and stability of solutions. Examples demonstrate how the use of Lipschintz constants can provide insights into the qualitative behaviour of solutions to some nonlinear problems.
• #### Building Immersive Data Visualizations for the Web

We present our early work on building prototype applications for Immersive Analytics using emerging standards-based web technologies for VR. For our preliminary investigations we visualize 3D bar charts that attempt to resemble recent physical visualizations built in the visualization community. We explore some of the challenges faced by developers in working with emerging VR tools for the web, and in building effective and informative immersive 3D visualizations.

• #### Cantilevers-on-membrane design for broadband MEMS piezoelectric vibration energy harvesting

Most MEMS piezoelectric vibration energy harvesters involve either cantilever-based topologies, doubly-clamped beams or membrane structures. While these traditional designs offer simplicity, their frequency response for broadband excitation are typically inadequate. This paper presents a new integrated cantilever-on-membrane design that attempts to both optimise the strain distribution on a piezoelectric membrane resonator and improve the power responsiveness of the harvester for broadband excitation. While a classic membrane-based resonator has the potential to theoretically offer wider operational frequency bandwidth than its cantilever counterpart, the addition of a centred proof mass neutralises its otherwise high strain energy regions. The proposed topology addresses this issue by relocating the proof mass onto subsidiary cantilevers and integrates the merits of both the membrane and the cantilever designs. When experimentally subjected to a band-limited white noise excitation, up to approximately two folds of power enhancement was observed for the new membrane harvester compared to a classic plain membrane device.
• #### Capsule membranes encapsulated with smart nanogels for facile detection of trace lead(II) ions in water

A novel method based on capsule membranes encapsulated with smart nanogels is successfully developed for facilely detecting trace lead(II) (Pb2+) ions, which are hazardous to both human health and the environment because of their toxicity. The capsule membrane system is composed of a semi-permeable calcium alginate membrane and encapsulated poly(N-isopropylacrylamide-co-acryloylamidobenzo-18-crown-6) (PNB) nanogels. The semi-permeable membrane allows Pb2+ ions and water to pass through quickly, but rejects the encapsulated nanogels and polymers totally. As soon as Pb2+ ions appear in the aqueous environment and enter into the capsule, they can be specifically recognized by encapsulated PNB nanogels via forming 18-crown-6/Pb2+ complexes that cause a Pb2+-induced phase transition of PNB nanogels from hydrophobic to hydrophilic state. As a result, the osmotic pressure inside the capsule membrane increases remarkably, and thus the elastic capsule membrane isothermally swells upon the presence of Pb2+ ions in the environmental aqueous solution. The Pb2+-induced swelling degree of the capsule membrane is dependent on the concentration of Pb2+ ions ([Pb2+]) in water. Thus, the [Pb2+] value in water is able to be easily detected by directly measuring the Pb2+-induced isothermal swelling ratio of the capsule membrane, which we demonstrate by using 15 prepared capsule membranes arranged in a line. The Pb2+-induced swelling ratios of the capsule membrane groups are easily observed with the naked eye, and the detection limit of the [Pb2+] in water is 10-9 mol L-1. Such a proposed method provides an easy and efficient strategy for facile detection of trace threat analytes in water.
• #### Carbon dioxide rich microbubble acceleration of biogas production in anaerobic digestion

This paper addresses the use of anaerobic bacteria to convert carbon dioxide to biomethane as part of the biodegradation process of organic waste. The current study utilises gaslift bioreactors with microbubbles generated by fluidic oscillation to strip the methane produced in the gaslift bioreactor. Removal of methane makes its formation thermodynamically more favourable. In addition, intermittent sparging of microbubbles can prevent thermal stratification, maintain uniformity of the pH and increase the intimate contact between the feed and microbial culture with lower energy requirements than traditional mixing. A gaslift bioreactor with microbubble sparging has been implemented experimentally, using a range of carrier gas, culminating in pure carbon dioxide, in the anaerobic digestion process. The results obtained from the experiments show that the methane production rate is approximately doubled with pure carbon dioxide as the carrier gas for intermittent microbubble sparging.
• #### Cardiovascular disease and healthy ageing

Cardiovascular diseases are main cause of morbidity and mortality in the Western World. Cardiovascular disease increases in its prevalence with age and the burden of this condition is set to increase with an Ageing global population. There are many factors that impact cardiovascular disease risk. The aim of this brief commentary is to explore some of these factors; specifically, we will examine the role of social status, nutrition and, psychological stress in modulating cardiovascular disease risk. Our aim is to emphasise the multidimensional nature of this condition and to stress that a more complete understanding of the mechanisms which underpin its pathology can only be achieved by adopting an integrated approach which treats the progression of this disease in a more holistic fashion.
• #### Characterising small solutions in delay differential equations through numerical approximations

This paper discusses how the existence of small solutions for delay differential equations can be predicted from the behaviour of the spectrum of the finite dimensional approximations.
• #### Characterising small solutions in delay differential equations through numerical approximations

This article discusses how the existence of small solutions for delay differential equations can be predicted from the behaviour of the spectrum of the finite dimensional approximations.
• #### Characteristic functions of differential equations with deviating arguments

The material here is motivated by the discussion of solutions of linear homogeneous and autonomous differential equations with deviating arguments. If $a, b, c$ and $\{\check{\tau}_\ell\}$ are real and ${\gamma}_\natural$ is real-valued and continuous, an example with these parameters is $$u'(t) = \big\{a u(t) + b u(t+\check{\tau}_1) + c u(t+\check{\tau}_2) \big\} { \red +} \int_{\check{\tau}_3}^{\check{\tau}_4} {{\gamma}_\natural}(s) u(t+s) ds \tag{\hbox{\rd{\star}}} .$$ A wide class of equations ($\rd{\star}$), or of similar type, can be written in the {\lq\lq}canonical{\rq\rq} form $$u'(t) =\DSS \int_{\tau_{\rd \min}}^{\tau_{\rd \max}} u(t+s) d\sigma(s) \quad (t \in \Rset), \hbox{ for a suitable choice of } {\tau_{\rd \min}}, {\tau_{\rd \max}} \tag{\hbox{{\rd \star\star}}}$$ where $\sigma$ is of bounded variation and the integral is a Riemann-Stieltjes integral. For equations written in the form (${\rd{\star\star}}$), there is a corresponding characteristic function $$\chi(\zeta) ):= \zeta - \DSS \int_{\tau_{\rd \min}}^{\tau_{\rd \max}} \exp(\zeta s) d\sigma(s) \quad (\zeta \in \Cset), \tag{\hbox{{\rd{\star\star\star}}}}$$ %%($\chi(\zeta) \equiv \chi_\sigma (\zeta)$) whose zeros (if one considers appropriate subsets of equations (${\rd \star\star}$) -- the literature provides additional information on the subsets to which we refer) play a r\^ole in the study of oscillatory or non-oscillatory solutions, or of bounded or unbounded solutions. We show that the related discussion of the zeros of $\chi$ is facilitated by observing and exploiting some simple and fundamental properties of characteristic functions.