Assessing the effect of the electrode orientation on the performance of soil microbial fuel cells

Soil microbial fuel cells (SMFCs) are a sub-class of the microbial fuel cells family, in which the soil acts as the electrolyte, and as the source of microorganisms and organic fuel. Given the great simplicity of the system design, SMFCs show a promising avenue for energy generation in remote areas. In this study, we investigate the influence that geometrical factors, such as the electrode orientation, have on the electrochemical performance of SMFCs. Two types of electrode orientations: horizontal and vertical, were tested. Additionally, the influence of anode and cathode immersion in soil was explored too. Our results demonstrate that vertical positioning of the cathode in soil is not a viable option. The increase in cathodic immersion leads to a more rapid performance decay, attributed to more anaerobic conditions along soil’s depth. The increase in anode immersion has a positive effect on the evolution of the negative electrode potential. However, with the increase in electrode spacing, the performance drops due to a greater internal resistance.

An hp-version adaptive finite element algorithm for eigensolutions of moderately thick circular cylindrical shells via error homogenisation and higher-order interpolation

PurposeThis study presents a novel hp-version adaptive finite element method (FEM) to investigate the high-precision eigensolutions of the free vibration of moderately thick circular cylindrical shells, involving the issues of variable geometrical factors, such as the thickness, circumferential wave number, radius and length.Design/methodology/approachAn hp-version adaptive finite element (FE) algorithm is proposed for determining the eigensolutions of the free vibration of moderately thick circular cylindrical shells via error homogenisation and higher-order interpolation. This algorithm first develops the established h-version mesh refinement method for detecting the non-uniform distributed optimised meshes, where the error estimation and element subdivision approaches based on the superconvergent patch recovery displacement method are introduced to obtain high-precision solutions. The errors in the vibration mode solutions in the global space domain are homogenised and approximately the same. Subsequently, on the refined meshes, the algorithm uses higher-order shape functions for the interpolation of trial displacement functions to reduce the errors quickly, until the solution meets a pre-specified error tolerance condition. In this algorithm, the non-uniform mesh generation and higher-order interpolation of shape functions are suitable for addressing the problem of complex frequencies and modes caused by variable structural geometries.FindingsNumerical results are presented for moderately thick circular cylindrical shells with different geometrical factors (circumferential wave number, thickness-to-radius ratio, thickness-to-length ratio) to demonstrate the effectiveness, accuracy and reliability of the proposed method. The hp-version refinement uses fewer optimised meshes than h-version mesh refinement, and only one-step interpolation of the higher-order shape function yields the eigensolutions satisfying the accuracy requirement.Originality/valueThe proposed combination of methodologies provides a complete hp-version adaptive FEM for analysing the free vibration of moderately thick circular cylindrical shells. This algorithm can be extended to general eigenproblems and geometric forms of structures to solve for the frequency and mode quickly and efficiently.

A Computational Descriptor Analysis on Excited State Behaviours of a Series of TADF and Non-TADF Compounds

The thermally activated delayed fluorescence (TADF) behaviours of seventeen organic TADF emitters and two non-TADF chromophores bearing various donor and acceptor moieties were investigated, focusing on their torsion angles, singlet-triplet gap (ΔEST), spin orbit couplings (SOC) and topological ΦS index. Electronic structure calculations were performed in the framework of the Tamm-Dancoff approximation (TDA) allowing to characterize reverse intersystem crossing (RISC) probability between the S1 and T1 states. In addition, experimental ΔEST data were taken into account to choose the most appropriate functional and basis set, while absorption spectra were obtained by considering vibrational and dynamical effects through a Wigner sampling of the ground state equilibrium regions. Examining all the parameters obtained in our computational study, we rationalized the influence of electron-donating and electron-accepting groups and the effects of geometrical factors, namely torsion angles, on a wide class of diverse compounds ultimately providing an easy and computationally effective protocol to assess TADF efficiencies.

Impact of tricuspid annular shape on late worsening tricuspid regurgitation after transcatheter aortic implantation: insight from multidetector row computed tomography assessment

Background Worsening of tricuspid regurgitation (TR) in patients undergoing transcatheter aortic valve implantation (TAVI) is associated with adverse clinical outcomes. The geometrical factors that determine the occurrence of significant TR after TAVI are uncertain. Multi-detector row computed tomography (MDCT) may provide additional geometrical insights in the pathophysiology of worsening TR after TAVI. Purpose To investigate the impact of right atrial and tricuspid annular (TA) geometryassessed by MDCT on the occurrence of significant TR (≥ moderate) at 1-year after TAVI. Methods Patients without significant TR who had undergone a full-beat MDCT prior to TAVI were included. Right and left atrial and ventricular volumes and TA parameters including the anterior-posterior (AP) and septal-lateral (SL) diameters, area and circularity (AP/SL ratio) were measured and correlated to the occurrence of significant TR at 1-year after TAVI. Results A total of 205 patients (80±7 years, 51% male) who underwent TAVI for severe aortic stenosiswere included. Moderate or severe TR at 1-year follow-up occurred in 59 patients (29%). Patients who developed significant TR were more likely to have atrial fibrillation and lower left ventricular (LV) volumes, but larger right and left atrial volumes and TA dimensions at baseline. After adjusting for atrial fibrillation and LV and right atrial volumes, larger end-diastolic TA SL diameter (odds-ratio 1.182 95% CI 1.047–1.334, P=0.007) and more circular TA shape were independently associated with the occurrence of significant TR. Conclusion In patients without significant TR prior to TAVI, TA dilation and loss of the elliptical shape of the TA at baseline are associated with of the occurrence of significant TR 1-year after TAVI. FUNDunding Acknowledgement Type of funding sources: Private grant(s) and/or Sponsorship. Main funding source(s): ESC research grant 2018 Representative cases

The Role of Interfacial Adhesion in Polymer Composites Engineered from Lignocellulosic Agricultural Waste

This paper presents a comprehensive study about the application of a lignocellulosic agricultural waste, sunflower husk in different polymer composites. Two types of milled sunflower husk with different geometrical factors were incorporated into polypropylene, low-density and high-density polyethylene, polystyrene (PS), glycol-modified polyethylene terephthalate (PETG) and polylactic acid (PLA). The filler content of the composites varied between 0 and 60 vol%. The components were homogenized in an internal mixer and plates were compression molded for testing. The Lewis–Nielsen model was fitted to the moduli of each composite series, and it was found that the physical contact of the filler particles is a limiting factor of composite modulus. Interfacial interactions were estimated from two independent approaches. Firstly, the extent of reinforcement was determined from the composition dependence of tensile strength. Secondly, the reversible work of adhesion was calculated from the surface energies of the components. As only weak van der Waals interactions develop in the interphase of polyolefins and sunflower husk particles, adhesion is weak in their composites resulting in poor reinforcement. Interfacial adhesion enhanced by specific interactions in the interphase, such as π electron interactions for PS, hydrogen bonds for PLA, and both for PETG based composites.

Dry granular masses impacting on rigid obstacles: numerical analysis and theoretical modelling

The assessment of the time evolution of the impact force exerted by dry flowing masses on rigid obstacles is mandatory for the dynamic design of sheltering structures and the evaluation of the vulnerability of existing structures. In this paper, the results of an extensive numerical campaign performed by employing a discrete element method (DEM) code are presented and the role of different geometrical factors (flow length, height and front inclination) and state parameters (porosity and velocity) on the impact force–time evolution is investigated. The impact process is studied to correlate local information with the macroscopic response and a physically based force–time function, generalising the formula already introduced by the authors for the assessment of maximum impact force, in which each parameter is correlated with the previously mentioned factors, is proposed.

Quantitative Relationships Between Growth, Differentiation, and Shape That Control Drosophila Eye Development and Its Variation

The size of organs is critical for their function and often a defining trait of a species. Still, how organs reach a species-specific size or how this size varies during evolution are problems not yet solved. Here, we have investigated the conditions that ensure growth termination, variation of final size and the stability of the process for developmental systems that grow and differentiate simultaneously. Specifically, we present a theoretical model for the development of the Drosophila eye, a system where a wave of differentiation sweeps across a growing primordium. This model, which describes the system in a simplified form, predicts universal relationships linking final eye size and developmental time to a single parameter which integrates genetically-controlled variables, the rates of cell proliferation and differentiation, with geometrical factors. We find that the predictions of the theoretical model show good agreement with previously published experimental results. We also develop a new computational model that recapitulates the process more realistically and find concordance between this model and theory as well, but only when the primordium is circular. However, when the primordium is elliptical both models show discrepancies. We explain this difference by the mechanical interactions between cells, an aspect that is not included in the theoretical model. Globally, our work defines the quantitative relationships between rates of growth and differentiation and organ primordium size that ensure growth termination (and, thereby, specify final eye size) and determine the duration of the process; identifies geometrical dependencies of both size and developmental time; and uncovers potential instabilities of the system which might constraint developmental strategies to evolve eyes of different size.

Influence of different domain configurations on WRF solar irradiance estimation at Badajoz (Spain)

<p>Over the last decades, numerical prediction models, such as the Weather Research and Forecasting (WRF), have emerged as one of the most powerful tools for solar radiation exploitation as renewable energy. A reliable forecast of solar radiation is an effective method to account for its variability and facilitate its integration into the grid. This study analyzes the influence of different domain configurations and spatial resolutions on the WRF solar radiation estimation. To this aim, different domain configurations centered on the city of Badajoz (Spain) have been tested. Thus, three different combinations of two nested domains (D01; higher domain; D02; inner domain) defined on a Lambert Conformal projection have been analyzed. Configurations C1 and C2 use the same domains but differ in the resolution of the nested domain (D02): 9 km for C1 and 3 km for C2. C3 has been defined to perform simulations at a higher resolution, consisting of two nested domains of 9 km for D01 and 1 km for D02. Due to WRF’s requirements on grid ratio between nested domains and computational efficiency criteria, this third configuration uses the same D02 dimensions as C1 and C2, but notably smaller D01 dimensions. All these configurations have employed the same WRF parameterizations. The initial and lateral boundary conditions for the meteorological fields are obtained from the reanalysis ERA5. Finally, the estimated solar radiation for the inner domains at 9, 3 and 1 km has been compared with ground-based solar radiation measurements. The results show a good performance of all the analyzed configurations, with an average relative MABE value of 14.95% and mean relative RMSE of 23.7%. Linear regression analysis between simulated and reference ground measurements have reported a slope of 0.83 for C1, 0.80 for C2 and 0.77 for C3. C3 tends to overestimate the reference measurements, while C1 and C2 tend to underestimate them. This underestimation is more remarkable for C2, likely due to the higher grid ratio in this configuration, 1:9 versus 1:3 in C1. Additionally, the analysis of differences between WRF simulation and reference data with respect to geometrical factors and sky conditions have reported differences between configurations. All these results reveal that different aspects related to the domain configuration, and not only final resolution, can influence the solar radiation forecasting and point out the need to find the most suitable configuration for each specific problem. <em>Acknowledgments.</em> This work is partially funded by FEDER/Ministerio de Ciencia, Innovación y Universidades-Agencia Estatal de Investigación of Spain through project RTI 2018-097332-B-C22, and by Junta de Extremadura-FEDER through project GR18097.</p>