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Selective light transmission in agrivoltaics: Modeling light spectra and photosynthetic rate
Get PDFWhile most agrivoltaic systems use opaque silicon photovoltaics, their excessive shading has shifted interest toward semi-transparent wavelength-selective photovoltaic (WSPV) technologies. These technologies aim to transmit light beneficial for crops’ growth while converting unused wavelengths into electricity. This study presents two modeling approaches: one for simulating light transmission through WSPV systems and the other for estimating leaf photosynthetic rates from the wavelengths received at the crop level. Both models incorporate the composition of the light spectrum, an aspect often overlooked in earlier models where broadband light values were sufficient. However, in WSPV systems, consideration of the spectral light distribution is key. The models were validated using experimental data from semi-transparent magenta-colored cadmium telluride (CdTe) WSPV systems, demonstrating satisfactory accuracy (R2 > 0.89). Additionally, the study evaluates two metrics, the yield photon flux (YPF) and effective photosynthetically active radiation (EPAR), to assess the photosynthetic efficiency of WSPV technologies in terms of light quality. A global crop suitability assessment, based on light requirements (light quantity) for different plants, highlights the potential of various WSPV technologies in agrivoltaics and aims to guide their future implementation. For instance, semi-transparent magenta CdTe PV and red-transmittance-dominated organic PV (OPV) modules, with average PAR light transmittance around 20%, appear to provide effective shading in most regions. These systems can support medium-light plants (daily light integral [DLI] >6 mol m−2 day−1) even in higher latitudes during sunnier months. Conversely, blue-dominated OPV and a neutral-colored semi-transparent crystalline silicon PV provide higher transmittance (around 50%), making them suitable for plants with very high light demands (DLI >16 mol m−2 day−1), but the quality of the light transmitted is less efficient or unaltered in terms of photosynthetic performance with respect to sunlight
Direct Conversion of Ethanol to Ethyl Acetate by Dynamic Polyoxometalate/Carbon Nanohorn Electrocatalytic Interfaces
No full text: The electrosynthesis of ethyl acetate (EtOAc) by oxidative esterification of aqueous (up to 20% water) ethanol (EtOH) is performed by employing the tetraruthenate polyoxometalate [Ru4(μ-O)4(μ-OH)2(H2O)4(γ-SiW10O36)2]10- (Ru4POM) electrocatalyst with carbon nanohorns (CNHs) as a heterogeneous support. This strategy involves a voltage-gated electro-adsorption of Ru4POM on CNH-modified glassy carbon anodes with favorable interfacial dynamics, maintained under electrocatalytic conditions. These conditions are reached through the continuous reconstruction of the organic/inorganic interface (catch-and-release), as probed by converging thermal, microscopic, and electrochemical analyses. In fact, control experiments reveal that both pristine and N-doped CNHs display a Ru4POM loading in the range 13-18 nmol mg-1 with a remarkable ∼100 mV onset potential anticipation and current enhancement in the range 400-700% compared to the homogeneous conditions. By adopting the "catch-and-release" protocol, electro-esterification of aqueous EtOH features long-term stability of the productive current in the mA range (Jchrono ≈ 2 mA cm-2 at +1.2 V vs Ag/AgCl probed up to 18 h), with Faradaic efficiencies, FEEtOAc, of >90%. This effect is attributed to the crucial role of CNHs hydrophobicity to control hydrolysis equilibria, thus outperforming the solution-phase behavior, which levels off at FEEtOAc < 60%
Critical behavior of epidemics depending on the interplay between temporal scales and human behavior
No full textThe spatial spread of infectious diseases is ruled by two processes: the disease progression and human behavior, which comprises human contacts and human mobility. A standard modeling approach is to define an epidemiological model upon a metapopulation network under some restrictive assumptions, such as that all processes happen at the same time scale, dispersal is diffusive, and agents are indistinguishable with respect to age and behavioral features. Although several models relax at least one of those assumptions, providing new insights about an epidemic, rarely are they relaxed all at once. Here, we introduce a model whose equations explicitly contain two parameters that encode the ratios between the time scales of the recovery, contact, and mobility processes, while simultaneously accounting for the age structure of the agents, different mobility layers, and different social settings for contacts. Furthermore, to reflect more closely real-world scenarios, we consider two settings: a diffusion-based one in which agents disperse like particles to spread the epidemics, effectively changing the starting population size far from and at equilibrium, and a force-based one where spread happens without changing the population of patches far from equilibrium. For both spreading frameworks, we study the regimes under which they provide distinct results and the critical properties of the epidemic process, finding that the curve of the critical points, which separate increasing or decreasing trends in the number of infected individuals – as well as other macroscopic observables of interest such as the attack rate – in the space of the two scale parameters exhibits a critical point itself. Complementing spatially-oriented strategies, the proposed approaches can contribute to the design of effective non-pharmaceutical interventions by focusing on the mutual influence of temporal scales, dispersal dynamics, and human behavior. In particular, our study allows for an optimal tuning of mobility and contact restrictions based on the characteristics of the disease and its spatial distribution in the early phase of spreading
Metabolic Models, in Silico Trials, and Algorithms
No full textArtificial pancreas (AP) systems, also called automated insulin delivery systems, have improved the time in range of glucose levels, reduced the daily burden of the user for glucose regulation, and improved their quality of life. Several commercially available AP systems operate in hybrid closed-loop mode that requires manual information from the user for meals and exercise. This article summarizes the progress on mathematical models of glucose-insulin dynamics, continuous glucose monitoring systems, and insulin pumps that form the building blocks of AP systems, the shift from animal studies to in silico clinical trials that accelerated the rate of progress in AP technologies and the efforts for developing the next-generation AP systems, and the fully automated AP that eliminates manual inputs and mitigates the effects of disturbances to glucose homeostasis—meals, physical activities, acute stress, and variations in sleep characteristics. A section is devoted to discuss the unique glycemic management challenges faced by women with diabetes across the lifespan (menstrual cycle, menopause, pregnancy) and summarize progress made to reduce their impact on glycemic management
A comprehensive review of small bowel length measurement: methodological challenges and variability factors
Get PDFThe measurement of small bowel length (SBL) is crucial in clinical contexts such as surgical planning, assessment of nutritional absorption and management of conditions like short bowel syndrome (SBS) and Crohn’s disease (CD). However, the literature reports substantial variations in measurements of average SBL, influenced by a multitude of methodological and patient-specific factors. The present review provides a comprehensive analysis of existing methodologies for SBL measurement, including intraoperative and radiologic approaches, detailing their strengths, limitations, and sources of error. The key factors influencing measurement variability are discussed, including methodological differences related to the measurement tool (e.g. intraoperative vs. imaging-based), bowel preparation process (e.g. stretching of the bowel), starting reference points. Additionally, inter-individual characteristics (e.g. height, BMI, sex) and population-specific factors (e.g. patients with SBS or CD) are assessed for their contribution to SBL variability. The aim pertains to informing clinical practice by providing a critical evaluation of measurement techniques and variability factors that impair standardized measurements of SBL to support research for clinical practice
