Optimisation of electrochemical sensors based on molecularly imprinted polymers: from OFAT to machine learning

: Molecularly imprinted polymers (MIPs) rely on synthetic engineered materials able to selectively bind and intimately recognise a target molecule through its size and functionalities. The way in which MIPs interact with their targets, and the magnitude of this interaction, is closely linked to the chemical properties derived during the polymerisation stages, which tailor them to their specific target. Hence, MIPs are in-deep studied in terms of their sensitivity and cross-reactivity, further being used for monitoring purposes of analytes in complex analytical samples. As MIPs are involved in sensor development within different approaches, a systematic optimisation and rational data-driven sensing is fundamental to obtaining a best-performant MIP sensor. In addition, the closer integration of MIPs in sensor development requires that the inner properties of the materials in terms of sensitivity and selectivity are maintained in the presence of competitive molecules, which focus is currently opened. Identifying computational models capable of predicting and reporting the best-performant configuration of electrochemical sensors based on MIPs is of immense importance. The application of chemometrics using design of experiments (DoE) is nowadays increasingly adopted during optimisation problems, which largely reduce the number of experimental trials. These approaches, together with the emergent machine learning (ML) tool in sensor data processing, represent the future trend in design and management of point-of-care configurations based on MIP sensing. This review provides an overview on the recent application of chemometrics tools in optimisation problems during development and analytical assessment of electrochemical sensors based on MIP receptors. A comprehensive discussion is first presented to cover the recent advancements on response surface methodologies (RSM) in optimisation studies of MIPs design. Therefore, the recent advent of machine learning in sensor data processing will be focused on MIPs development and analytical detection in sensors

Reflectometric System for Continuous and Automated Monitoring of Irrigation in Agriculture

In this work, a time domain reflectometry (TDR)-based system for continuous and diffused monitoring of soil water content in agriculture is presented. The proposed TDR-based system employs elongate sensing elements (SEs). In practical application, each wire-like SE is buried along the cultivation row to be monitored, and through a single TDR measurement it is possible to retrieve the water content profile of the cultivation along the length of the SE. By connecting the TDR-based monitoring system to the irrigation machines, it would be possible to automatically start/stop irrigation based on the actual water requirement of the cultivations, thus favoring precision agriculture and enhancing irrigation efficiency. To demonstrate the feasibility of the proposed monitoring solution, a dedicated hardware+software platform was developed and the TDR-based system was experimented in open-field cultivations

Accuracy improvement in the TDR-based localization of water leaks

A time domain reflectometry (TDR)-based system for the localization of water leaks has been recently developed by the authors. This system, which employs wire-like sensing elements to be installed along the underground pipes, has proven immune to the limitations that affect the traditional, acoustic leak-detection systems.Starting from the positive results obtained thus far, in this work, an improvement of this TDR-based system is proposed. More specifically, the possibility of employing a low-cost, water-absorbing sponge to be placed around the sensing element for enhancing the accuracy in the localization of the leak is addressed.To this purpose, laboratory experiments were carried out mimicking a water leakage condition, and two sensing elements (one embedded in a sponge and one without sponge) were comparatively used to identify the position of the leak through TDR measurements. Results showed that, thanks to the water retention capability of the sponge (which maintains the leaked water more localized), the sensing element embedded in the sponge leads to a higher accuracy in the evaluation of the position of the leak. Keywords: Leak localization, TDR, Time domain reflectometry, Water leaks, Underground water pipe

Combined Punctual and Diffused Monitoring of Concrete Structures Based on Dielectric Measurements

This work presents a microwave reflectometry-based system for monitoring large concretestructures (during the curing process and also while the structure is in use), through the combineduse of punctual and diffused sensing elements. In particular, the adoption of punctual probes ona reference concrete specimen allows the development of an innovative and accurate calibrationprocedure, useful to obtain the value of the water content on a larger structure made of the samematerial. Additionally, a wire-like diffused sensing element can be permanently embedded inbuildings and used to monitor the structure along the entire length of the sensing element. Theadopted diffused sensing element can be used not only to detect dielectric variation during the curingprocess, but also throughout the service life of the structure. The combined use of punctual anddiffused sensing elements represents an important innovation from a procedural point of view, ableto provide detailed and quantitative information on the health status of the structure both duringand after construction

Microwave reflectometric systems and monitoring apparatus for diffused-sensing applications

Most sensing networks rely on punctual/local sensors; they thus lack the ability to spatially resolve the quantity to be monitored (e.g. a temperature or humidity profile) without relying on the deployment of numerous inline sensors. Currently, most quasi-distributed or distributed sensing technologies rely on the use of optical fibre systems. However, these are generally expensive, which limits their large-scale adoption. Recently, elongated sensing elements have been successfully used with time-domain reflectometry (TDR) to implement diffused monitoring solutions. The advantage of TDR is that it is a relatively low-cost technology, with adequate measurement accuracy and the potential to be customised to suit the specific needs of different application contexts in the 4.0 era. Based on these considerations, this paper addresses the design, implementation and experimental validation of a novel generation of elongated sensing element networks, which can be permanently installed in the systems that need to be monitored and used for obtaining the diffused profile of the quantity to be monitored. Three applications are considered as case studies: monitoring the irrigation process in agriculture, leak detection in underground pipes and the monitoring of building structures

NOPAL: Natural Origin Protective for Artistic buildings in Lecce stone. Preliminary results.

EnThe work presents the preliminary results of the experimentation of innovative coatings for the protection of artefacts in Lecce stone. Starting from the cladodium of the species Opuntia Ficus-Indica (NOPAL), plant extracts were obtained and their performance have been studied through aging tests and the use of optical and spectroscopic methods, in order to develop a new ecofriendly product, that meets the requirements of non-toxicity, biodegradability, and low cost, and able to efficiently preserve the built heritage made of Lecce stone.ItIl lavoro presenta i risultati preliminari ottenuti dalla sperimentazione in laboratorio di innovativi protettivi green per la protezione dei materiali artistici in pietra leccese. A partire dalla specie Opuntia Ficus-Indica (NOPAL) sono stati ottenuti degli estratti vegetali e le loro performance sono state studiate attraverso test di invecchiamento e l'uso di metodologie ottiche e spettroscopiche, con il fine ultimo di formulare un nuovo prodotto ecofriendly che risponda ai requisiti di non tossicità, biodegradabilità, biocompatibilità, economicità

On the use of a reliable low-cost set-up for characterization measurements of antennas

In this paper, a low-cost time domain-based approach to antenna characterization is presented. The goal is to prove that time domain-based antenna measurements, after appropriate processing, represent an accurate and more practicable alternative to the universally accepted (yet highly expensive) antenna measurements in anechoic chamber, and provide information just as complete. Measurements on two commercial antennas are carried out in the time domain (in a non-controlled environment) and in the frequency domain (in an anechoic chamber): experimental data obtained from the two approaches are compared in terms of Return Loss. Results show that reliable results can be extracted from time domain data, and that a good insight into the antenna characteristics can be obtained even without using highly expensive facilities

Thiostrepton, a resurging drug inhibiting the stringent response to counteract antibiotic-resistance and expression of virulence determinants in Neisseria gonorrhoeae

: Due to the increased resistance to all available antibiotics and the lack of vaccines, Neisseria gonorrhoeae (the gonococcus) poses an urgent threat. Although the mechanisms of virulence and antibiotic resistance have been largely investigated in this bacterium, very few studies have addressed the stringent response (SR) that in pathogenic bacteria controls the expression of genes involved in host-pathogen interaction and tolerance and persistence toward antibiotics. In this study, the results of the transcriptome analysis of a clinical isolate of N. gonorrhoeae, after induction of the SR by serine hydroxamate, provided us with an accurate list of genes that are transcriptionally modulated during the SR. The list includes genes associated with metabolism, cellular machine functions, host-pathogen interaction, genome plasticity, and antibiotic tolerance and persistence. Moreover, we found that the artificial induction of the SR in N. gonorrhoeae by serine hydroxamate is prevented by thiostrepton, a thiopeptide antibiotic that is known to interact with ribosomal protein L11, thereby inhibiting functions of EF-Tu and EF-G, and binding of pppGpp synthase I (RelA) to ribosome upon entry of uncharged tRNA. We found that N. gonorrhoeae is highly sensitive to thiostrepton under in vitro conditions, and that thiostrepton, in contrast to other antibiotics, does not induce tolerance or persistence. Finally, we observed that thiostrepton attenuated the expression of key genes involved in the host-pathogen interaction. These properties make thiostrepton a good drug candidate for dampening bacterial virulence and preventing antibiotic tolerance and persistence. The ongoing challenge is to increase the bioavailability of thiostrepton through the use of chemistry and nanotechnology

Characterization of microplastics in water bottled in different packaging by Raman spectroscopy

Raman spectroscopy was applied to quantitatively and qualitatively characterize microplastics (MPs) in bottled water packaged in three different materials: polyethylene terephthalate (PET), recycled PET (rPET) and glass. The results showed a low mean concentration of MPs in all samples, with higher values in glass bottles (8.65 +/- 5.39 p L-1) than in PET (5.09 +/- 3.28 p L-1) or rPET (3.33 +/- 1.34 p L-1) bottles. Through the use of a method capable of detecting smaller particles, MPs of 20-100 mu m were dominant and fragments were the most abundant particle shape. PET was the prevalent polymer in PET bottles underlying the possible contribution of packaging in MP contamination, while polyethylene (PE) with additives prevailed in rPET and glass bottles, suggesting a contribution from the cap. A standardized protocol would allow comparable data to be obtained and allow an objective assessment of exposure, in view of plans to monitor contaminants of emerging concern (including MPs) under recent European legislation.MPs were detected by Raman spectroscopy in bottled water from different packaging