In silico experiments as a tool to reduce preclinical tests of magnetic hyperthermia

In silico models can be useful tools to guide preclinical tests of magnetic hyperthermia, which employs Magnetic Nanoparticles (MNPs) excited by AC magnetic fields, as heat mediators for cancer cure. We virtually reproduce the heating process induced by magnetic hyperthermia in murine models, as a function of field applicator features, properties and size of target tissue, MNP dose and animal size

Synergetic Application of Zero-, One-, and Three-Dimensional Computational Fluid Dynamics Approaches for Hydrogen-Fuelled Spark Ignition Engine Simulation

Nowadays hydrogen, especially if derived from biomass or produced by renewable power, is rising as a key energy solution to shift the mobility of the future toward a low-emission scenario. It is well known that hydrogen can be used with both internal combustion engines (ICEs) and fuel cells (FCs); however, hydrogen-fuelled ICE represents a robust and cost-efficient option to be quickly implemented under the current production infrastructure. In this framework, this article focuses on the conversion of a state-of-the-art 3.0L diesel engine in a hydrogen-fuelled Spark Ignition (SI) one. To preliminarily evaluate the potential of the converted ICE, a proper simulation methodology was defined combining zero-, one-, and three-dimensional (0D/1D/3D) Computational Fluid Dynamics (CFD) approaches. First of all, a detailed kinetic scheme was selected for both hydrogen combustion and Nitrogen Oxides (NOx) emission predictions in a 3D-CFD environment. Afterward, to bring the analysis to a system-level approach, a 1D-CFD predictive combustion model was firstly optimized by implementing a specific laminar flame speed correlation and, secondly, calibrated against the 3D-CFD combustion results. The combustion model was then integrated into a complete engine model to assess the potential benefit derived from the wide range of flammability and the high flame speed of hydrogen on a complete engine map, considering NOx formation and knock avoidance as priority parameters to control. Without a specific modification of turbocharger and combustion systems, a power density of 34 kW/L and a maximum brake thermal efficiency (BTE) of about 42% were achieved, thus paving the way for further hardware optimization (e.g., compression ratio reduction, turbocharger optimization, direct injection [DI]) to fully exploit the advantages enabled by hydrogen combustion

Shallow subsurface imaging of the Piano di Pezza active normal fault (central Italy) using high-resolution refraction and electrical resistivity tomography coupled with time-domain electromagnetic data

The Piano di Pezza fault (PPF) is the north-westernmost segment of the >20 km long Ovindoli-Pezza active normal fault-system (central Italy). Although existing paleoseismic data document high vertical Holocene slip rates (~1 mm/yr) and a remarkable seismogenic potential of this fault, its subsurface setting and Pleistocene cumulative displacement are still unknown. We investigated the shallow subsurface of a key section of the PPF using seismic and electrical resistivity tomography coupled with time-domain electromagnetic measurements (TDEM). We provide 2-D Vp and resistivity images showing details of the fault structure and the geometry of the shallow basin infill down to 35-40 m depth. We can estimate the dip and the Holocene vertical displacement of the master fault. TDEM measurements in the fault hangingwall indicate that the pre-Quaternary carbonate basement may be found at ~90-100 m depth

Geomorfología y Sedimentología del sector medio del valle de pueblo llano, Andes de Mérida, Venezuela

Un análisis geomorfológico y sedimentológico fue realizado en el sector medio del Valle de Pueblo Llano con la finalidad de comprender la génesis de los sedimentos y geoformas cuaternarias presentes en el área. Cuatro sectores con características morfológicas y sedimentológicas distintivas fueron identificados: (i) depósitos en masa de flujos de detritos con una expresión superficial cónica interpretados como abanicos aluviales, (ii) depósitos de flujos unidimensionales que constituyen terrenos relativamente planos con bajas pendientes característicos de terrazas fluviales, (iii) depósitos de diamicton que constituyen un conjunto de lomos y depresiones en forma de arco asociados a un complejo de morrenas frontales, y (iv) depósitos de flujos unidimensionales que conforman terrenos con forma de lomos asimétricos, asociados a condiciones fluvio-glaciares. Estos resultados ponen en evidencia que los glaciares asociados a la Glaciación Mérida en el Valle de Pueblo Llano, alcanzaron elevaciones al menos 300 m más bajas que las reportadas previamente en la literatura para los Andes de Mérida. Además, sugieren que otros valles glaciares presentes en los Andes de Mérida pudieron haber experimentado fenómenos similares.   Palabras clave: Andes de Mérida, Geomorfología y Sedimentología, Morrenas, Glaciación Mérida, Pueblo Llano.   Abstract: A geomorphological and sedimentological analysis was carried out in the Middle reach of the Pueblo Llano Valley to understand sediment genesis and quaternary geoforms present in the area. Four zones with distinctive morphological and sedimentological characteristics were identified: (i) mass deposits of debris flow with a cone-shaped surface interpreted as alluvial fans, (ii) unidirectional flow deposits with relatively flat topography, with little slope, characteristic of fluvial terraces, (iii) arc-shaped diamicton deposits that constitute a set of crests and valleys, associated to a complex of frontal moraines, and (iv) unidirectional flow deposits that form terrains with the shape of asymmetric ridges, associated to a fluvio-glacial conditions. These results show that the glaciers of the Mérida Glaciation in the Pueblo Llano Valley reached elevations of at least 500 m lower than those previously reported in the literature for the Mérida Andes. In addition, they suggest that other glacial valleys present in the Andes of Mérida might have experienced similar phenomena.   Keywords: Mérida Andes, Geomorphology and Sedimentolology, Moraine complex, Mérida Glaciation, Pueblo Llano

MRI-based radiomics to predict response in locally advanced rectal cancer: comparison of manual and automatic segmentation on external validation in a multicentre study

Background: Pathological complete response after neoadjuvant chemoradiotherapy in locally advanced rectal cancer (LARC) is achieved in 15–30% of cases. Our aim was to implement and externally validate a magnetic resonance imaging (MRI)-based radiomics pipeline to predict response to treatment and to investigate the impact of manual and automatic segmentations on the radiomics models. Methods: Ninety-five patients with stage II/III LARC who underwent multiparametric MRI before chemoradiotherapy and surgical treatment were enrolled from three institutions. Patients were classified as responders if tumour regression grade was 1 or 2 and nonresponders otherwise. Sixty-seven patients composed the construction dataset, while 28 the external validation. Tumour volumes were manually and automatically segmented using a U-net algorithm. Three approaches for feature selection were tested and combined with four machine learning classifiers. Results: Using manual segmentation, the best result reached an accuracy of 68% on the validation set, with sensitivity 60%, specificity 77%, negative predictive value (NPV) 63%, and positive predictive value (PPV) 75%. The automatic segmentation achieved an accuracy of 75% on the validation set, with sensitivity 80%, specificity 69%, and both NPV and PPV 75%. Sensitivity and NPV on the validation set were significantly higher (p = 0.047) for the automatic versus manual segmentation. Conclusion: Our study showed that radiomics models can pave the way to help clinicians in the prediction of tumour response to chemoradiotherapy of LARC and to personalise per-patient treatment. The results from the external validation dataset are promising for further research into radiomics approaches using both manual and automatic segmentations

MRI-based radiomics to predict response in locally advanced rectal cancer: comparison of manual and automatic segmentation on external validation in a multicentre study

BACKGROUND: Pathological complete response after neoadjuvant chemoradiotherapy in locally advanced rectal cancer (LARC) is achieved in 15–30% of cases. Our aim was to implement and externally validate a magnetic resonance imaging (MRI)-based radiomics pipeline to predict response to treatment and to investigate the impact of manual and automatic segmentations on the radiomics models. METHODS: Ninety-five patients with stage II/III LARC who underwent multiparametric MRI before chemoradiotherapy and surgical treatment were enrolled from three institutions. Patients were classified as responders if tumour regression grade was 1 or 2 and nonresponders otherwise. Sixty-seven patients composed the construction dataset, while 28 the external validation. Tumour volumes were manually and automatically segmented using a U-net algorithm. Three approaches for feature selection were tested and combined with four machine learning classifiers. RESULTS: Using manual segmentation, the best result reached an accuracy of 68% on the validation set, with sensitivity 60%, specificity 77%, negative predictive value (NPV) 63%, and positive predictive value (PPV) 75%. The automatic segmentation achieved an accuracy of 75% on the validation set, with sensitivity 80%, specificity 69%, and both NPV and PPV 75%. Sensitivity and NPV on the validation set were significantly higher (p = 0.047) for the automatic versus manual segmentation. CONCLUSION: Our study showed that radiomics models can pave the way to help clinicians in the prediction of tumour response to chemoradiotherapy of LARC and to personalise per-patient treatment. The results from the external validation dataset are promising for further research into radiomics approaches using both manual and automatic segmentations. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s41747-022-00272-2

User-centered design and development of TWIN-Acta: A novel control suite of the TWIN lower limb exoskeleton for the rehabilitation of persons post-stroke

Introduction: Difficulties faced while walking are common symptoms after stroke, significantly reducing the quality of life. Walking recovery is therefore one of the main priorities of rehabilitation. Wearable powered exoskeletons have been developed to provide lower limb assistance and enable training for persons with gait impairments by using typical physiological movement patterns. Exoskeletons were originally designed for individuals without any walking capacities, such as subjects with complete spinal cord injuries. Recent systematic reviews suggested that lower limb exoskeletons could be valid tools to restore independent walking in subjects with residual motor function, such as persons post-stroke. To ensure that devices meet end-user needs, it is important to understand and incorporate their perspectives. However, only a limited number of studies have followed such an approach in the post-stroke population. Methods: The aim of the study was to identify the end-users needs and to develop a user-centered-based control system for the TWIN lower limb exoskeleton to provide post-stroke rehabilitation. We thus describe the development and validation, by clinical experts, of TWIN-Acta: a novel control suite for TWIN, specifically designed for persons post-stroke. We detailed the conceived control strategy and developmental phases, and reported evaluation sessions performed on healthy clinical experts and people post-stroke to evaluate TWIN-Acta usability, acceptability, and barriers to usage. At each developmental stage, the clinical experts received a one-day training on the TWIN exoskeleton equipped with the TWIN-Acta control suite. Data on usability, acceptability, and limitations to system usage were collected through questionnaires and semi-structured interviews. Results: The system received overall good usability and acceptability ratings and resulted in a well-conceived and safe approach. All experts gave excellent ratings regarding the possibility of modulating the assistance provided by the exoskeleton during the movement execution and concluded that the TWIN-Acta would be useful in gait rehabilitation for persons post-stroke. The main limit was the low level of system learnability, attributable to the short-time of usage. This issue can be minimized with prolonged training and must be taken into consideration when planning rehabilitation. Discussion: This study showed the potential of the novel control suite TWIN-Acta for gait rehabilitation and efficacy studies are the next step in its evaluation process

Improvement of Hyperthermia Properties of Iron Oxide Nanoparticles by Surface Coating

Magnetic hyperthermia is an oncological therapy that exploits magnetic nanoparticles activated by radiofrequency magnetic fields to produce a controlled temperature increase in a diseased tissue. The specific loss power (SLP) of magnetic nanoparticles or the capability to release heat can be improved using surface treatments, which can reduce agglomeration effects, thus impacting on local magnetostatic interactions. In this work, Fe3O4 nanoparticles are synthesized via a coprecipitation reaction and fully characterized in terms of structural, morphological, dimensional, magnetic, and hyperthermia properties (under the Hergt–Dutz limit). Different types of surface coatings are tested, comparing their impact on the heating efficacy and colloidal stability, resulting that sodium citrate leads to a doubling of the SLP with a substantial improvement in dispersion and stability in solution over time; an SLP value of around 170 W/g is obtained in this case for a 100 kHz and 48 kA/m magnetic field