27 research outputs found
The ability of deep eutectic solvent systems to extract bioactive compounds from apple pomace
No full textThe objective of this study was to examine the bioactivity of extracts from apple pomace obtained by non-conventional green extraction methods (DES systems). Bioactivity was antioxidant capacity and ability to stimulate insulin secretion from pancreatic beta-cells. The antioxidant capacity of extracts was examined using the DPPH and the FRAP assay. Impact of the extracts on cell viability and insulin secretion were examined using the BRIN-BD11 cell line. ChCl:EG(1:4) extracts resulted in high antioxidant capacity in the DPPH assay (80.1% inhibition versus 11.3%). Extracts obtained from the classical systems demonstrated an ability to promote insulin secretion significantly higher than the positive control, p < 0.05. ChCl:EG(1:4) extracts stimulated insulin secretion to a lesser extent. Overall, the data provides evidence for the potential of DES systems to extract bioactive compounds from apple pomace that have relevance for metabolic health. Further optimisation of the extraction procedures should be tailored to the desired bioactive properties
Electronic phase separation at LaAlO3/SrTiO3 interfaces tunable by oxygen deficiency
No full textElectronic phase separation is crucial for the fascinating macroscopic properties of the LaAlO3/SrTiO3 (LAO/STO) paradigm oxide interface, including the coexistence of superconductivity and ferromagnetism. We investigate this phenomenon using angle-resolved photoelectron spectroscopy (ARPES) in the soft-x-ray energy range, where the enhanced probing depth combined with resonant photoexcitation allow us access to fundamental electronic structure characteristics - momentum-resolved spectral function, dispersions and ordering of energy bands, Fermi surface - of buried interfaces. Our experiment uses x-ray irradiation of the LAO/STO interface to tune its oxygen deficiency, building up a dichotomic system where mobile weakly correlated Ti t(2g) electrons coexist with localized strongly correlated Ti e(g) ones. The ARPES spectra dynamics under x-ray irradiation shows a gradual intensity increase under constant Luttinger count of the Fermi surface. This fact identifies electronic phase separation (EPS) where the mobile electrons accumulate in conducting puddles with fixed electronic structure embedded in an insulating host phase, and allows us to estimate the lateral fraction of these puddles. We discuss the physics of EPS invoking a theoretical picture of oxygen-vacancy clustering, promoted by the magnetism of the localized Ti e(g) electrons, and repelling of the mobile t(2g) electrons from these clusters. Our results on the irradiation-tuned EPS elucidate the intrinsic one taking place at the stoichiometric LAO/STO interfaces
Terahertz photodetectors based on tapered semiconductor nanowires
No full textWe report on the demonstration of Terahertz (THz) broadband detectors based on field effect transistors exploiting tapered semiconductor nanowires. The intrinsic asymmetry provided by the nanowires geometry allows to achieve responsivity values as high as 55 V/W (2.5 mA/W) and a noise-equivalent-power of 3 x 10(-10) W/Hz(1/2) independent of the specific gate voltage applied. The possibility to reduce the number of terminals required to the source and drain contacts only and the technological feasibility of multi-pixel arrays are promising for the realization of compact and integrated THz matrix array detection systems
Quantitative Study of Triboemission Kinetics from Polymer Fiber-Reinforced Mortar Paving Blocks: Unraveling the Dynamics of Nanoparticle Aerosol Release
No full textTriboemission_data.xlsx
DVS_data.xlsx
N2_isotherm_data.xlsx
He pycnometry_data.xlsx
Raman_data.xlsxMortar blocks with addition of recycled polyurethane fibers (PUF) were subjected to abrasion using an original pin-on-disk tribometer in order to investigate the kinetic parameters and emission mechanisms of fine and ultrafine aerosol nanoparticles and the effect of the fiber concentration on the mechanical, tribological, and triboemission properties. Three different samples, referred as A (20% substitution level), B (40%), and C (60%) and a reference sample (Ref.) were analyzed for this study. The abrasion was performed in an environment chamber with filtered air using a stationary alumina sphere, 20 mm in diameter, which was pressed against the rotating sample using a dead weight of 1.3 kg. The sliding speed was 1 m s-1. A quantitative methodology was employed to assess the deposition rate, particle size distribution, and emissivity. The triboemission properties were correlated with the pore structure, morphology and tribochemical transformations of the particles and worn surfaces. The specific surface area, distribution of micro- and mesopore sizes, and skeleton density were evaluated through a comprehensive analysis involving three distinct methods: dynamic water adsorption, N2 adsorption, and He pycnometry. The mechanically affected zones were characterized using white-light confocal microscopy and Raman spectroscopy. The function of the particle size distribution exhibited two modes, with the most probable particle size falling within the range of 115-156 nm. Interestingly, the PUFs addition did not changed considerably the size of the particles. The aggregation of PUFs resulted in a gradual increase in the volume of pores, particularly mesopores, as well as an increase in the specific surface area.
The study's results demonstrated a decline in the deposition rate of aerosol particles within the 10 to 60 nm aerodynamic diameter range as the concentration of PUFs increased. This observation strongly suggested the occurrence of direct emission of polymeric aerosol particles resulting from the abrasion of PUFs.
The findings of this research provide valuable insights into the intricate relationship between material composition, particle size distribution, porosity, and emission kinetics.The work was funded by the Ministry of Science and Innovation of Spain with the contribution from the European Regional Development Fund and the European Union NextGenerationEU / PRTR through the contracts PID2019-111063RB-I00, TED2021-129950B-I00 and PDC2022-134014-I00. Also, the support was provided by the Regional Government of Castilla y León (BU070P20).Triboemission_data.xlsx DVS_data.xlsx N2_isotherm_data.xlsx He pycnometry_data.xlsx Raman_data.xlsxPeer reviewe
Droplet interactions during combustion of unsupported droplet clusters in microgravity: numerical study of droplet interactions at low reynolds number
No full textThe present work developed a numerical model to study the combustion of wellcharacterized drop clusters in microgravity environment using direct numerical simulation by the means of Fire Dynamic Simulator – a CFD model of fire-driven fluid flow. The computational research investigated the combustion of clusters of droplets of different sized and asymmetric three-dimensional configurations in zero gravity environments for zero relative Reynolds numbers. One of the aspects studied is droplet interaction during evaporation and combustion over the lifetime of the droplet. The model developed accounts for variable gas-phase thermophysical properties, unity Lewis number, Stefan velocities and includes the gas-phase radiative transfer (solved by a finite volume method) for finite rate reaction. Mass burning rates are calculated for each droplet in an array and compared to mass burning rate of similar single droplet, the ratio of these two being a correction factor η. Single droplet combustion has been studied to evaluate and validate the model output. It was found that single droplet combustion does follow the d2-law, mass burning rates being in excellent qualitative agreement with current theories and experimental data. Direct numerical results of multiple droplet combustion were obtained and compared with a point source method as well as with experimental and numerical models developed in the past. Data obtained with proposed method provided results consistent with and in qualitative agreement with multiple droplets combustion theories and experimental investigations. Quantitatively, the numerical model results were in the range of 85% to 95% of the results provided by the investigations found in the literature for droplet array combustion models and in the range of 85% to 90% when compared with single droplet combustion models. The numerical simulation along with the future proposed experiment described in the project is a unique combination of investigative methods that will provide support for future investigations and for understanding of droplet interaction phenomena.Ph.D., Mechanical Engineering -- Drexel University, 200
A family of chiral ionic liquids from the natural pool: Relationships between structure and functional properties and electrochemical enantiodiscrimination tests
No full textIn spite of the increasing fundamental and practical interest of electrochemistry in ionic liquids (ILs), exploration of chiral ionic liquids (CILs) in view of
enantioselective electrochemistry and electroanalysis is surprisingly overdue. In this study a family of chiral ionic liquids (CILs) based on natural chiral building
blocks, of easy synthesis, is detailedly characterized in terms of thermal and electrochemical properties, achieving valuable information about structure-property relationships on account of the systematicity of available family terms. Moreover, they are submitted to a series of chiral electroanalysis tests. Cyclic
voltammetry in bulk CILs or with CIL as additives in a bulk achiral ionic liquid IL, shows small but statistically signifi cant potential differences for the enantiomers of two quite different chiral probes, an interesting result since enantiodiscrimination in terms of potential differences in chiral voltammetry
(more desirable respect to current differences) has been only seldom obtained so far. The present first example of enantioselective voltammetry in CIL media
with stereocenters as localized chirality sources also offers an important and so far missing confirmation of the intrinsically superior level of the
inherent chirality strategy, recently resulting in larger potential differences with the same protocols implemented in "inherently chiral" ionic liquid media. Furthermore, an alternative transduction mode, based on electrochemical impedance spectroscopy EIS, is proposed to effectively highlight the enantiodiscrimination ability of CIL media in analytical experiments
Design and Synthesis of Ionic Liquid-Based Matrix Metalloproteinase Inhibitors (MMPIs): A Simple Approach to Increase Hydrophilicity and to Develop MMPI-Coated Gold Nanoparticles
No full textSelective and potent matrix metalloproteinase 12 (MMP-12) inhibitors endowed with improved hydrophilicity are highly sought for potential use in the treatment of lung and cardiovascular diseases. In the present paper, we modified the structure of a nanomolar MMP-12 inhibitor by incorporating an ionic liquid (IL) moiety to improve aqueous solubility. Four biologically active salts were obtained by linking the sulfonamide moiety of the MMP-12 inhibitor to imidazolium-, pyrrolidinium-, piperidinium-, and DABCO-based ILs. The imidazolium-based bioactive salt was tested on human recombinant MMPs and on monocyte-derived dendritic cells, showing activity similar to that of the parent compound, but improved water solubility. The imidazolium-based bioactive salt was then used to prepare electrostatically stabilized MMP inhibitor-coated gold nanoparticles (AuNPs) able to selectively bind MMP-12. These AuNPs were used to study subcellular localization of MMP-12 in monocyte-derived dendritic cells by transmission electron microscopy analysis
Quantitative study of triboemission kinetics from polymer fiber-reinforced mortar paving blocks: Unravelling the dynamics of nanoparticle aerosol release
No full textTriboemission of nanoparticle aerosols from construction materials is a growing concern due to its potential impact on air quality and human health. In this study, we investigated the effect of aggregation of polyurethane fibers (PUFs) proceeding from waste on the kinetics of triboemission in cement mortars. A quantitative methodology was employed to assess the deposition rate, particle size distribution, and emissivity for the aerosols within the particle aerodynamic diameter range of 10–400 nm. The triboemission properties were correlated with the pore structure, morphology and tribochemical transformations of the particles and worn surfaces. Our results highlight the intricate influence of PUF aggregation on the kinetics of triboemission in cement mortars through both direct and indirect mechanisms and provide valuable insights into the mechanisms governing triboemission in construction materials.The work was funded by the Ministry of Science and Innovation of Spain with the contribution from the European Regional Development Fund and the European Union NextGenerationEU / PRTR through the contracts PID2019-111063RB-I00, TED2021-129950B-I00, PRE2020-092472 and PDC2022-134014-I00. Also, the support was provided by the Regional Government of Castilla y León (BU070P20).Peer reviewe
Innovative Chiral Materials and Media for Enantioselection in Chiral Electrochemistry and Advanced Applications in Spintronics
No full textThe highest degree of selectivity in electrochemical recognition is achieved with enantioselective electroanalysis, implying the ability to discriminate specular images of a given electroactive molecule, an issue particularly important in the biological and pharmaceutical fields [1]. In fact the enantiomers of a chiral molecule have identical physico-chemical properties and would have identical electrochemical behaviour excepting when reacting in a diastereomeric context (diastereoisomers are energetically different). Unprecedented enantiorecognition in terms of large potential differences was recently observed in analytical experiments by our research group[2], implementing:
1) enantiopure electrode surfaces based on inherently chiral heterocycle-based electroactive films (with different stereogenic elements, C2 axis vs helix);
2) enantiopure media based on inherently chiral (or simply chiral) ionic liquids or related additives dissolved in an achiral medium [3,4];
3) Deep Eutectic Solvents (DES), commonly defined as systems composed of a mixture of at least two components, a hydrogen bond acceptor (HBA) and a hydrogen bond donor (HBD).
An even more striking feature implying inherently chiral films was obtained in the frame of the CISS (Chiral Induced Spin Selectivity) effect, recently unveiled by Ron Naaman and co-workers, where spin polarization in photo-ejected electrons transmitted through a thin layer of enantiopure material on gold was observed [5]. In this frame we present an innovative set-up which includes i) a non-ferromagnetic electrode (ITO) modified with a thin electroactive chiral film (the spin filter), ii) achiral redox couples dissolved in aqueous or organic solutions and iii) an external permanent magnet which was placed near the chiral film. A spectacular unforeseen effect was observed by means of cyclovoltammetry (CV), in fact CV peaks recorded in the presence of achiral redox couples reveal an impressive potential shift by flipping the magnet orientation (north vs south). This effect was also specular by changing the spin injector configuration. The importance of these studies includes possible applications in the field of spintronics, electronics, chemical sensoristic and so on and provides a striking evidence of the spin selectivity properties of chiral thin films [6].
References:
[1]S. Arnaboldi, T. Benincori, R. Cirilli, S. Grecchi, L. Santagostini, F. Sannicolò, P. R. Mussini, (2016), ABC, 408, 26, 7243.
[2]S. Arnaboldi, S. Grecchi, M. Magni, P. Mussini, (2018), Curr. Opinion, 8, 60
[3]S. Arnaboldi, M. Magni, P. Mussini, (2018), Curr. Opinion, 7, 188.
[4]M. Longhi, S. Arnaboldi, E. Husanu, S. Grecchi, I. F. Buzzi, R. Cirilli, S. Rizzo, C. Chiappe, P. R. Mussini, L. Guazzelli, (2019), Electrochimica Acta, 298, 194.
[5]B Dor, S. Yochelis, S. P. Mathew, R. Naaman, Y. Paltiel, (2013) Nat. Commun. 4, 3256.
[6]Benincori, S. Arnaboldi, M. Magni, S. Grecchi, R. Cirilli, C. Fontanesi, P. R. Mussini, (2019), Chem. Sci, 10, 2750
Electrochemistry of, and electrochemistry in, chiral and inherently chiral ionic liquid media
No full textIonic liquids ILs are attractive media for electrochemistry and electroanalysis, since, in addition to other useful properties, they provide both solvent and supporting electrolyte; moreover, they feature an extremely well defined structure at the interphase with a charged electrode, resembling somehow a bulk liquid crystal, extending for many layers, also standing in the presence of water traces, and possibly tunable by in-situ present additives. [1-3] For this reason chiral ionic liquids (CILs), of which a rich palette is already available, are surprisingly still nearly unexplored by electrochemists, in spite of appearing quite attractive, since they could transmit chiral information more effectively than chiral organic solvents or chiral supporting electrolytes. [1]
In this context, we have recently started a detailed investigation of (a) bio-based chiral ionic liquids and (b) inherently chiral ionic liquids (ICILs), investigating both their physico-chemical and electrochemical features and their performance as media for chiral electroanalysis experiments. Our bio-based CILs featu- re cations with a building block of natural origin, including one or more localized stereocentres, from which their chirality arises (as in most so far available CILs) [4]. Instead, in our ICILs chirality is intrinsic of the whole biheteroaromatic cation, which features a stereogenic axis related to a torsion between two equal heteroaromatic moieties, with a related energy barrier too high to be overcome at room temperature, so that the ICIL can be obtained in two stable enantiopure antipodes. In inherently chiral molecules and materials both chirality and functional properties originate from the same structural element, which can coincide with the main molecular backbone; thus their chirality manifestations can be very powerful, as recently evidenced by some of us in electroanalytical, chiroptical and magneto-electrochemistry experiments with electrodes modified by inherently chiral oligomer thin films.
Actually, while interesting but (at least so far) small are the chirality effects observed working in our bio- based CILs with localized stereocentres [4], large peak potential differences have been observed for the enantiomers of very different chiral probes in CV experiments in an enantiopure bulk ICIL. Very conve- niently, impressive enantiodiscrimination is observed even using ICILs (or other related inherently chiral molecular salts, solid at room T, but of easier synthesis) as low-concentration chiral additives in common achiral ionic liquids (ILs) [5,6]. Furthermore, similar impressive performances have also been observed dissolving in an achiral IL a thiahelicene-based additive, an inherently chiral oligothiophene, but un- charged and based on a different stereogenic element, i.e. a helical scaffold. Among possible explanations we are considering the possibility of a chiral reorganization effect by the inherently chiral additives in the locally highly ordered IL structure at the interphase with the charged electrode, similarly to the well- known transitions from nematic to cholesteric order induced by chiral additives in bulk liquid crystals.
The support of Fondazione Cariplo/Regione Lombardia "Avviso congiunto per l’incremento del- l’attrattività del sistema di ricerca lombardo e della competitività dei ricercatori candidati su strumenti ERC - edizione 2016” (Project 2016-0923) is gratefully acknowledged.
[1] S. Arnaboldi, M. Magni, P.R. Mussini, Curr. Opin. Electrochem. 8 (2018) 60-72.
[2] K. Ma, R. Jarosova, G.M. Swain, G.J. Blanchard, Langmuir 32 (2016) 9507-9512.
[3] A.Lahiri Cui, T. Carstens, N. Borisenko, G. Pulletikurthi, C. Kuhl, F. Endres, J. Phys. Chem. C 120 (2016) 9341-9349.
[4] M. Longhi, S. Arnaboldi, E. Husanu, S. Grecchi, I.F. Buzzi, R. Cirilli, S. Rizzo, C. Chiappe, P.R. Mussini, L. Guazzelli, Electrochim. Acta 298 (2019) 194-209.
[5] S. Rizzo, S. Arnaboldi, V. Mihali, R. Cirilli, A. Forni, A. Gennaro, A.A. Isse, M. Pierini, P.R. Mussini, F. Sannicolò, Angew. Chem. Int. Ed. 56 (2017) 2079-2082.
[6] S. Rizzo, S. Arnaboldi, R. Cirilli, A. Gennaro, A.A. Isse, F. Sannicolò, P.R. Mussini, Electrochem. Comm. 89 (2018) 57-61
