A diagnostic procedure for improving the structure of approximated kinetic models

Kinetic models of chemical and biochemical phenomena are frequently built from simplifying assumptions. Whenever a model is falsified by data, its mathematical structure should be modified embracing the available experimental evidence. A framework based on maximum likelihood inference is illustrated in this work for diagnosing model misspecification and improving the structure of approximated models. In the proposed framework, statistical evidence provides a measure to justify a modification of the model structure, namely a reduction of complexity through the removal of irrelevant parameters and/or an increase of complexity through the replacement of relevant parameters with more complex state-dependent expressions. A tailored Lagrange multipliers test is proposed to support the scientist in the improvement of parametric models when an increase in model complexity is required

Model-based design of experiments in the presence of structural model uncertainty: an extended information matrix approach

The identification of a parametric model, once a suitable model structure is proposed, requires the estimation of its non-measurable parameters. Model-based design of experiment (MBDoE) methods have been proposed in the literature for maximising the collection of information whenever there is a limited amount of resources available for conducting the experiments. Conventional MBDoE methods do not take into account the structural uncertainty on the model equations and this may lead to a substantial miscalculation of the information in the experimental design stage. In this work, an extended formulation of the Fisher information matrix is proposed as a metric of information accounting for model misspecification. The properties of the extended Fisher information matrix are presented and discussed with the support of two simulated case studies

Aerosol mediated localized dissolution to enhance the electrical behavior and sensitivity of piezoresistive nanofiber-based flexible sensors

This work proposes the use of solvents in the form of small size droplets to improve the connections among nanofibers (NFs) in electrospun composite nanofibers with carbon nanotube multiwalled (MWCNT) by improving the electrical and piezoresistive behavior of such electrically conductive polymer composites. The here proposed Aerosol Mediated Localized Dissolution (AMLD) process has been shown to be effective in improving the 3D microporous NF mat by inducing local dissolution that is effective in improving the connections among fibers within the mat. The AMLD process is demonstrated here for polyethylene oxide (PEO) / MWCNTs composite nanofibers, showing that the electrical conductivity is particularly improved in those samples with low content of MWCNTs, even below the original percolation threshold. The improved electrical conductivity is coupled with exceptional sensitivity of the flex sensor for low MWCNTs contents, this is particularly due to the ability of the AMLD process to preserve the high surface area of the 3D mat by inducing better fiber-to-fiber contacts in few regions only. In addition, this work demonstrates the effectiveness of applying an electrical potential difference during the AMLD process to improve the alignment of MWCNTs within the 3D microporous NF mat. The combination of voltage and AMLD allow to obtain a gauge factor as high as 571.9 with a MWCNTs loading of 1 wt%

Aerogels for energy and environmental applications

Aerogels are emerging as one of the most intriguing and promising groups of microporous materials, characterized by impressive properties such as low density, high surface area, high porosity and tunable surface chemistry. Fostering unique thermal and acoustic insulation features, for several decades they mainly received attention from the aerospace and building sectors. More recently, new great opportunities arose due to significant advances in the drying technologies that currently, represent the enabling step for aerogel synthesis and fabrication. This process-ability dramatically increased the interest toward aerogels from new disciplines. This explains why in the last decade the Environmental Science and Energy fields significantly contributed to the expansion of the aerogel technology, suggesting novel uses and applications and contributing to extend the group of materials that can be synthetized by aerogel processing. New, unforeseen properties emerged for aerogel materials, such as adsorption of contaminants and fluids purification, catalysis of different reactions, electrical conductivity. The present short-review aims at providing a critical overview of the key advances in the development of aerogels for energy and environmental applications, especially emphasizing the common strategies and properties that are turning aerogels into one of the new key emerging technologies of these areas of science

Ferritin nanovehicle for targeted delivery of cytochrome C to cancer cells

In this work, we have exploited the unique properties of a chimeric archaeal-human ferritin to encapsulate, deliver and release cytochrome c and induce apoptosis in a myeloid leukemia cell line. The chimeric protein combines the versatility in 24-meric assembly and cargo incorporation capability of Archaeglobus fulgidus ferritin with specific binding of human H ferritin to CD71, the “heavy duty” carrier responsible for transferrin-iron uptake. Delivery of ferritin-encapsulated cytochrome C to the Acute Promyelocytic Leukemia (APL) NB4 cell line, highly resistant to transfection by conventional methods, was successfully achieved in vitro. The effective liberation of cytochrome C within the cytosolic environment, demonstrated by double fluorescent labelling, induced apoptosis in the cancer cells

A Multi-Objective Optimal Experimental Design Framework for Enhancing the Efficiency of Online Model-Identification Platforms

Recent advances in automation and digitization enable the close integration of physical devices with their virtual counterparts, facilitating the real-time modeling and optimization of a multitude of processes in an automatic way. The rich and continuously updated data environment provided by such systems makes it possible for decisions to be made over time to drive the process toward optimal targets. In many manufacturing processes, in order to achieve an overall optimal process, the simultaneous assessment of multiple objective functions related to process performance and cost is necessary. In this work, a multi-objective optimal experimental design framework is proposed to enhance the efficiency of online model-identification platforms. The proposed framework permits flexibility in the choice of trade-off experimental design solutions, which are calculated online—that is, during the execution of experiments. The application of this framework to improve the online identification of kinetic models in flow reactors is illustrated using a case study in which a kinetic model is identified for the esterification of benzoic acid (BA) and ethanol in a microreactor

Viral nervous necrosis outbreaks caused by the RGNNV/SJNNV reassortant betanodavirus in gilthead sea bream (Sparus aurata) and European sea bass (Dicentrarchus labrax)

Mediterranean marine aquaculture has suffered significant economic losses due to viral nervous necrosis (VNN) outbreaks mainly caused by different RGNNV betanodavirus strains. In recent years, the marine aquaculture sector has experienced the emergence of the RGNNV/SJNNV reassortant betanodavirus, harbouring the RNA1 segment of RGNNV genotype and the RNA2 segment of SJNNV genotype. So far, the reassortant strains caused massive mortality outbreaks in gilthead sea bream (Sparus aurata) larvae sparing the European sea bass (Dicentrarchus labrax). In this study, multiple mortality outbreaks occurred in one Italian marine hatchery involving both European sea bass and gilthead sea bream at different life stages were investigated through a complete microbiological and molecular analysis. Gilthead sea bream larvae and juveniles have recorded the highest mortality rates, however, both European sea bass and gilthead sea bream incurred a RGNNV/SJNNV reassortant betanodavirus persistent infection, able to act as asymptomatic carriers and viral source for susceptible fish. These new epidemiological data on nervous necrosis virus (NNV) reassortant infection provide precious advice on how to manage fish to reduce VNN spread in Mediterranean aquaculture. Evidence of interspecies transmission of RGNNV/SJNNV reassortant strains and the persistent infection in both European sea bass and gilthead sea bream, point out the importance to enforce a wide surveillance and a strict biosecurity programme addressing both RGNNV and reassortant RGNNV/SJNNV betanodaviruses in Mediterranean European sea bass and gilthead sea bream farms. Furthermore, the presence assessment of betanoviruses in all newly-introduced fish batches in the farm, regardless of the species and a strict segregation between European sea bass and gilthead sea bream batches within farms can significantly reduce the risk of NNV transmission. Finally, surviving fish can act as carrier fish, and thereby must be segregated from other batches and protected from stress conditions that could trigger a new clinical phase

Electrical conductivity modulation of crosslinked composite nanofibers based on PEO and PEDOT:PSS

The aim of this work is to investigate the development of nanofiber mats, based on intrinsically conductive polymers (ICPs), which show simultaneously a high electrical conductivity and mandatory insoluble water properties. In particular, the nanofibers, thanks to their properties such as high surface area, porosity, and their ability to offer a preferential pathway for electron flow, play a crucial role to improve the essential characteristics ensured by ICPs. The nanofiber mats are obtained by electrospinning process, starting from a polymeric solution made of polyethylene oxide (PEO) and poly(styrene sulfonate) (PEDOT:PSS). PEO is selected not only as a dopant to increase the electrical/ionic conductivity, as deeply reported in the literature, but also to ensure the proper stability of the polymeric jet, to collect a dried nanofiber mat. Moreover, in the present work, two different treatments are proposed in order to induce crosslinking between PEO chains and PEDOT:PSS, made insoluble into water which is the final sample. The first process is based on a heating treatment, conducted at 130°C under nitrogen atmosphere for 6 h, named the annealing treatment. The second treatment is provided by UV irradiation that is effective to induce a final crosslinking, when a photoinitiator, such as benzophenone, is added. Furthermore, we demonstrate that both crosslinking treatments can be used to verify the preservation of nanostructures and their good electrical conductivity after water treatment (i.e., water resistance). In particular, we confirm that the crosslinking method with UV irradiation results to being more effective than the standard annealing treatment. Indeed, we demonstrate that the processing time, required to obtain the final crosslinked nanofiber mats with a high electrical conductance, results to being smaller than the one needed during the heating treatment