a-multimodal-wide-field-fourier-transform-raman-microscope

A Multimodal Wide-Field Fourier-Transform Raman Microscope

Raman microscopy is a powerful technique to determine the chemical composition of a sample. The main challenge of the state-of-the-art spontaneous Raman ...

Politecnico di Milano

We address advective transport of a solute traveling toward a single pumping well in a two-dimensional randomly heterogeneous aquifer. The two random variables of interest are the trajectory followed by an individual particle from the injection point to the well location and the particle travel time under steady-state conditions. Our main objective is to derive the predictors of trajectory and travel time and the associated uncertainty, in terms of their first two statistical moments (mean and variance). We consider a solute that undergoes mass transfer between a mobile and an immobile zone. Based on Lawrence et al. [Lawrence, A.E., Sánchez-Vila, X., Rubin, Y., 2002. Conditional moments of the breakthrough curves of kinetically sorbing solute in heterogeneous porous media using multirate mass transfer models for sorption and desorption. Water Resour. Res. 38 (11), 1248, doi:10.1029/2001WR001006.], travel time moments can be written in terms of those of a conservative solute times a deterministic quantity. Moreover, the moments of solute particles trajectory do not depend on mass transfer processes. The resulting mean and variance of travel time and trajectory for a conservative species can be written as functions of the first, second moments and cross-moments of trajectory and velocity components. The equations are developed from a consistent second order expansion in sigmaY (standard deviation of the natural logarithm of hydraulic conductivity). Our solution can be completely integrated with the moment equations of groundwater flow of Guadagnini and Neuman [Guadagnini, A., Neuman, S.P., 1999a. Nonlocal and localized analyses of conditional mean steady state flow in bounded, randomly non uniform domains 1. Theory and computational approach. Water Resour. Res. 35(10), 2999-3018.,Guadagnini, A., Neuman, S.P., 1999b. Nonlocal and localized analyses of conditional mean steady state flow in bounded, randomly non uniform domains 2. Computational examples. Water Resour. Res. 35(10), 3019-3039.], it is free of distributional assumptions regarding the log conductivity field, and formally includes conditioning. We present analytical expressions for the unconditional case by making use of the results of Riva et al. [Riva, M., Guadagnini, A., Neuman, S.P., Franzetti, S., 2001. Radial flow in a bounded randomly heterogeneous aquifer. Transport in Porous Media 45, 139-193.]. The quality of the solution is supported by numerical Monte Carlo simulations. Potential uses of this work include the determination of aquifer reclamation time by means of a single pumping well, and the demarcation of the region potentially affected by the presence of a contaminant in the proximity of a well, whenever the aquifer is very thin and Dupuit-Forchheimer assumption holds.

Travel time and trajectory moments of conservative solutes in two-dimensional convergent flows.

We analyze the relative importance of the selection of (1) the geostatistical model depicting the structural heterogeneity of an aquifer, and (2) the basic processes to be included in the conceptual model, to describe the main aspects of solute transport at an experimental site. We focus on the results of a forced-gradient tracer test performed at the "Lauswiesen" experimental site, near Tübingen, Germany. In the experiment, NaBr is injected into a well located 52 m from a pumping well. Multilevel breakthrough curves (BTCs) are measured in the latter. We conceptualize the aquifer as a three-dimensional, doubly stochastic composite medium, where distributions of geomaterials and attributes, e.g., hydraulic conductivity (K) and porosity (phi), can be uncertain. Several alternative transport processes are considered: advection, advection-dispersion and/or mass-transfer between mobile and immobile regions. Flow and transport are tackled within a stochastic Monte Carlo framework to describe key features of the experimental BTCs, such as temporal moments, peak time, and pronounced tailing. We find that, regardless the complexity of the conceptual transport model adopted, an adequate description of heterogeneity is crucial for generating alternative equally likely realizations of the system that are consistent with (a) the statistical description of the heterogeneous system, as inferred from the data, and (b) salient features of the depth-averaged breakthrough curve, including preferential paths, slow release of mass particles, and anomalous spreading. While the available geostatistical characterization of heterogeneity can explain most of the integrated behavior of transport (depth-averaged breakthrough curve), not all multilevel BTCs are described with equal success. This suggests that transport models simply based on integrated measurements may not ensure an accurate representation of many of the important features required in three-dimensional transport models.

Relative importance of geostatistical and transport models in describing heavily tailed breakthrough curves at the Lauswiesen site.

Stentless valves have long been considered the ideal valves in terms of hemodynamics. Recently, the Trifecta valve, a stented bioprosthesis with excellent fluid dynamic characteristics, has become available. The aim of the study was to compare the opening/closing pattern of the Freestyle stentless valve and the Trifecta valve with that of the native aortic valve.

Opening/closing pattern of Trifecta and Freestyle valves versus native aortic valve: Are stentless valves more physiologic than a stented valve?

Heterogeneous colorimetric sensors for fluoride ions were obtained by cross-linking TEMPO-oxidized cellulose nanofibers (TOCNF) with chemically modified branched polyethyleneimine 25 kDa (bPEI). Functionalization of bPEI primary amino groups with aromatic anhydrides led to the formation of the corresponding mono- and bis-imides on the grafted polymers (f-bPEI). A microwave-assisted procedure allowed the optimization of the synthetic protocol by reducing reaction time from 17 h to 30 minutes. Hydrogels obtained by mixing different ratios of TOCNF, bPEI and f-bPEI were lyophilized and thermally treated at about 100 °C to promote the formation of amide bonds between the amino groups of poly-cationic polymers and the carboxylic groups of cellulose nanofibers. This approach generated a series of cellulose nanosponges S1-S3 which were characterized by FT-IR and by solid state  C CPMAS NMR. These sponge materials can act as colorimetric sensors for the selective naked-eye recognition of fluoride ions over chloride, phosphate and acetate ions at concentrations of up to 0.05 M in DMSO. Moreover, when the sponges were functionalized with perylene tetracarboxylic diimide, successful naked-eye detection was achieved with only 0.02 % w/w of chromophore units per gram of material.

Naked-Eye Heterogeneous Sensing of Fluoride Ions by Co-Polymeric Nanosponge Systems Comprising Aromatic-Imide-Functionalized Nanocellulose and Branched Polyethyleneimine.

Breast arterial calcifications (BAC) are a sex-specific cardiovascular disease biomarker that might improve cardiovascular risk stratification in women. We implemented a deep convolutional neural network for automatic BAC detection and quantification.

Detection and quantification of breast arterial calcifications on mammograms: a deep learning approach.

Our work targets mapping of pesticides application rates within the European Union at a 250 m spatial resolution. Source data include global estimates of pesticide inputs, high resolution crop maps and pesticide usage reported by EUROSTAT official figures. Previously published global pesticide application rates in PEST-CHEMGRIDS are used as first guess estimates. These are then adjusted using a calibration dataset gathered from pesticide use in agriculture. The estimation of the applied mass by country and crop type is then combined with high resolution crop maps. The procedure explicitly accounts for data quality and uncertainty through a Maximum Likelihood estimation procedure. This data product features detailed spatial distributions of pesticide inputs, facilitating evaluation of pesticide fate and transport, biogeochemical transformations as well as environmental risk assessment.

Pesticides application rate maps in the European Union at a 250 m spatial resolution.

The application by spray coating of low amounts (2-4 g/m) of cellulose nanofibers (CNF) onto three different paper substrates, a recycled one (RC, 130 g/m) and two food contact samples (FC45, 45 g/m and FC100, 100 g/m), allowed to investigate the impact of CNF typology and mechanical pre-treatment on the barrier performance against grease and air permeation. Two CNF additives were produced and characterized (TEM, XRD, FT-IR), differing for the production process: TEMPO-mediated oxidation (TOCNF) and enzymatic hydrolysis (ECNF). The crucial role of homogenization cycles to achieve nanoscale dimensions was correlated to the barrier response. TOCNF-based coatings performed better than ECNF ones, reaching a complete grease barrier (kit 12) both for RC and FC100, even at the lower consistencies. The addition of glycerol as plasticizer in formulations allowed to obtain a similar result for FC45, but just in the case of TOCNF-based coatings. A significant decrease of water permeability was also observed when applying TOCNF coating to RC (Cobb value from 138 g/m to 40.3 g/m) and a complete air barrier was measured at the higher consistency of both CNF as detected by Gurley test. SEM analysis of coated samples disclosed the effect of coatings on porous substrates.

Cellulose nanofibers for grease and air barrier properties enhancement: A comparison on recycled and food contact paper samples.

Environmental microbiota are essential yet often overlooked, with urbanization driving microbial diversity loss and diseases of civilization. Public misconceptions, exacerbated by COVID-19, have widened the gap between microbiologists and society, highlighting the need for science-society integration. The  () model offers a reproducible "citizen science" framework integrating research, education, and public engagement through large-scale microbiome sampling. Tested while assessing environmental microbiomes in different urbanized outdoors, 76 undergraduates participated in four sampling events, collecting 2429 samples in 8 h of effective sampling, achieving over than 303 samples/hour in 29 288.74 m. Manual metadata curation revealed only 0.58% critical errors and no data loss, emphasizing the effectiveness of structured submission forms in ensuring data quality. Educational outcomes, assessed through a validated survey, significant gains in participants' perceived skills, understanding, and knowledge of microbiome sampling compared to non-participants. The  model, including a step-by-step guide, illustrated protocol, and templates, is freely available for replication. Our findings demonstrate that citizen science can rival or complement traditional microbiome research in efficiency, scale, and data quality while broadening accessibility. BSDs offers a scalable tool to advance educational and societal, empower participation, and support informed decision-making.

Article	Year
Travel time and trajectory moments of conservative solutes in two-dimensional convergent flows. Journal of contaminant hydrology\| PubMed ID: 16216383	2006
Relative importance of geostatistical and transport models in describing heavily tailed breakthrough curves at the Lauswiesen site. Journal of contaminant hydrology\| PubMed ID: 18799231	2008
Opening/closing pattern of Trifecta and Freestyle valves versus native aortic valve: Are stentless valves more physiologic than a stented valve? Journal of cardiac surgery\| PubMed ID: 29119598	2017
Naked-Eye Heterogeneous Sensing of Fluoride Ions by Co-Polymeric Nanosponge Systems Comprising Aromatic-Imide-Functionalized Nanocellulose and Branched Polyethyleneimine. ChemPlusChem\| PubMed ID: 31943927	2019
Detection and quantification of breast arterial calcifications on mammograms: a deep learning approach. European radiology\| PubMed ID: 37160426	2023
Pesticides application rate maps in the European Union at a 250 m spatial resolution. Scientific data\| PubMed ID: 40312380	2025
Cellulose nanofibers for grease and air barrier properties enhancement: A comparison on recycled and food contact paper samples. Carbohydrate polymers\| PubMed ID: 40947225	2025
The Bicocca sampling days model: a participatory citizen science approach to environmental microbiome research and education. ISME communications\| PubMed ID: 41403706	2025

M. Riva

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