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Spectroscopic non-destructive methods have high potentialities as fast, cheap and easy-to-be-used approaches to address olive oil quality and authenticity. Based on previous research where near-UV Visible spectroscopy was used to investigate extra-virgin olive oils (EVOOs) and their main pigments’ content (i.e., β-carotene, lutein, pheophytin a and pheophytin b), we have implemented the spectral deconvolution method in order to follow the EVOO’s life, from ‘freshly pressed’ to ‘on-the-shelf’ EVOO samples at different storage time. In the first part of the manuscript, the new implemented deconvolution spectroscopic method aimed to quantify two additional pigments, namely chlorophyll a and chlorophyll b, is described and tested on ‘ad hoc’ samples with known concentrations of chlorophylls. The effect of light exposure and acidification was investigated to test the reliability and robustness of the spectral deconvolution. In the second part of the work, this approach was used to study the kinetic of pigments’ degradation in several monocultivar fresh EVOO samples under optimal storage’s conditions. The results here reported show that this spectroscopic deconvolution approach is a good method to study fresh EVOOs too; moreover, the proposed method revealed to be sensitive to detect eventual stresses of olive oil samples stored in not-good conditions.
Eleonora Borello; Daniele Roncucci; Valentina Domenici. Study of the Evolution of Pigments from Freshly Pressed to ‘On-the-Shelf’ Extra-Virgin Olive Oils by Means of Near-UV Visible Spectroscopy. Foods 2021, 10, 1891 .
AMA StyleEleonora Borello, Daniele Roncucci, Valentina Domenici. Study of the Evolution of Pigments from Freshly Pressed to ‘On-the-Shelf’ Extra-Virgin Olive Oils by Means of Near-UV Visible Spectroscopy. Foods. 2021; 10 (8):1891.
Chicago/Turabian StyleEleonora Borello; Daniele Roncucci; Valentina Domenici. 2021. "Study of the Evolution of Pigments from Freshly Pressed to ‘On-the-Shelf’ Extra-Virgin Olive Oils by Means of Near-UV Visible Spectroscopy." Foods 10, no. 8: 1891.
Olive oils and, in particular, extra-virgin olive oils (EVOOs) are one of the most frauded food. Among the different adulterations of EVOOs, the mixture of high-quality olive oils with vegetable oils is one of the most common in the market. The need for fast and cheap techniques able to detect extra-virgin olive oil adulterations was the main motivation for the present research work based on 1H NMR relaxation and diffusion measurements. In particular, the 1H NMR relaxation times, T1 and T2, measured at 2 and 100 MHz on about 60 EVOO samples produced in Italy are compared with those measured on four different vegetable oils, produced from macadamia nuts, linseeds, sunflower seeds, and soybeans. Self-diffusion coefficients on this set of olive oils and vegetable oil samples were measured by means of the 1H NMR diffusion ordered spectroscopy (DOSY) technique, showing that, except for the macadamia oil, other vegetable oils are characterized by an average diffusion coefficient sensibly different from extra-virgin olive oils. Preliminary tests based on both NMR relaxation and diffusometry methods indicate that eventual adulterations of EVOO with linseed oil and macadamia oil are the easiest and the most difficult frauds to be detected, respectively.
Donatella Ancora; Jerneja Milavec; Anton Gradišek; Mario Cifelli; Ana Sepe; Tomaž Apih; Boštjan Zalar; Valentina Domenici. Sensitivity of Proton NMR Relaxation and Proton NMR Diffusion Measurements to Olive Oil Adulterations with Vegetable Oils. Journal of Agricultural and Food Chemistry 2021, 1 .
AMA StyleDonatella Ancora, Jerneja Milavec, Anton Gradišek, Mario Cifelli, Ana Sepe, Tomaž Apih, Boštjan Zalar, Valentina Domenici. Sensitivity of Proton NMR Relaxation and Proton NMR Diffusion Measurements to Olive Oil Adulterations with Vegetable Oils. Journal of Agricultural and Food Chemistry. 2021; ():1.
Chicago/Turabian StyleDonatella Ancora; Jerneja Milavec; Anton Gradišek; Mario Cifelli; Ana Sepe; Tomaž Apih; Boštjan Zalar; Valentina Domenici. 2021. "Sensitivity of Proton NMR Relaxation and Proton NMR Diffusion Measurements to Olive Oil Adulterations with Vegetable Oils." Journal of Agricultural and Food Chemistry , no. : 1.
The interest in development of new non-destructive methods for characterization of extra virgin olive oils (EVOOs) has been increasing in the recent years. Among different experimental techniques, nuclear magnetic resonance (NMR) relaxation measurements are very promising in the field of food characterization and authentication. In this study, we focused on relaxation times T1 and T2 measured at different magnetic field strengths (namely, 2, 100, and 400 MHz) and 1H NMR T1 relaxometry dispersions directly on olive oil samples without any chemical/physical treatments. A large set of EVOO samples produced in two regions of Italy, Tuscany and Apulia, were investigated by means of 1H NMR relaxation techniques. The relaxation studies reported here show several common features between the two sets of EVOO samples, thus indicating that relaxation properties, namely, the ranges of values of T1 and T2 at 2 and 100 MHz, are characteristic of EVOOs, independently from the cultivars, climate, and geographic origin. This is a promising result in view of quality control and monitoring.
Anton Gradišek; Mario Cifelli; Donatella Ancora; Ana Sepe; Boštjan Zalar; Tomaž Apih; Valentina Domenici. Analysis of Extra Virgin Olive Oils from Two Italian Regions by Means of Proton Nuclear Magnetic Resonance Relaxation and Relaxometry Measurements. Journal of Agricultural and Food Chemistry 2021, 1 .
AMA StyleAnton Gradišek, Mario Cifelli, Donatella Ancora, Ana Sepe, Boštjan Zalar, Tomaž Apih, Valentina Domenici. Analysis of Extra Virgin Olive Oils from Two Italian Regions by Means of Proton Nuclear Magnetic Resonance Relaxation and Relaxometry Measurements. Journal of Agricultural and Food Chemistry. 2021; ():1.
Chicago/Turabian StyleAnton Gradišek; Mario Cifelli; Donatella Ancora; Ana Sepe; Boštjan Zalar; Tomaž Apih; Valentina Domenici. 2021. "Analysis of Extra Virgin Olive Oils from Two Italian Regions by Means of Proton Nuclear Magnetic Resonance Relaxation and Relaxometry Measurements." Journal of Agricultural and Food Chemistry , no. : 1.
Nuclear Magnetic Resonance (NMR) relaxometry is widely used for food products characterization. In order to exploit the full potential of the relaxation methods one can look at magnetic field dependence of spin-lattice relaxation. Analysis of relaxation dispersion characteristics of food systems may complement knowledge about composition and dynamics of their constituents, in particular, of water. In this article, we review the basic principles as well as recent applications of field-cycling NMR relaxometry in different food systems. The inter- and intra-molecular interactions modulated by molecular dynamics can be efficiently studied with NMR relaxometry. This method can be exploited for discrimination of liquids, determination of diffusion coefficient or paramagnetic ion concentration, observation of crystallization/solidification processes. The technique has already proven to be helpful to investigate changes occurring in food products due to different processing techniques and to detect food adulteration. FFC benchtop instruments represent a new frontier in food studies.
Elif Gokcen Ates; Valentina Domenici; Małgorzata Florek-Wojciechowska; Anton Gradišek; Danuta Kruk; Nadica Maltar-Strmečki; Mecit Oztop; Emin Burcin Ozvural; Anne-Laure Rollet. Field-dependent NMR relaxometry for Food Science: Applications and perspectives. Trends in Food Science & Technology 2021, 110, 513 -524.
AMA StyleElif Gokcen Ates, Valentina Domenici, Małgorzata Florek-Wojciechowska, Anton Gradišek, Danuta Kruk, Nadica Maltar-Strmečki, Mecit Oztop, Emin Burcin Ozvural, Anne-Laure Rollet. Field-dependent NMR relaxometry for Food Science: Applications and perspectives. Trends in Food Science & Technology. 2021; 110 ():513-524.
Chicago/Turabian StyleElif Gokcen Ates; Valentina Domenici; Małgorzata Florek-Wojciechowska; Anton Gradišek; Danuta Kruk; Nadica Maltar-Strmečki; Mecit Oztop; Emin Burcin Ozvural; Anne-Laure Rollet. 2021. "Field-dependent NMR relaxometry for Food Science: Applications and perspectives." Trends in Food Science & Technology 110, no. : 513-524.
Several spectroscopic techniques have been optimized to check extra-virgin olive oil quality and authenticity, as well as to detect eventual adulterations. These methods are usually complementary and can give information about different olive oil chemical components with bioactive and antioxidant properties. In the present work, a well-characterized set of extra-virgin olive oil (cultivar Frantoio) samples from a specific area of Tuscany (Italy) were investigated by combining near UV-Vis absorption spectroscopy, 1H and 13C nuclear magnetic resonance (NMR) to identify and quantify different chemical components, such as pigments, secoiridoids and squalene, related to the nutritional and quality properties of olive oils. Moreover, the pigmentation index of olives, organoleptic and sensory properties, total phenolic compound contents and the lipidic fractions of olive oils were investigated. The results obtained are, finally, compared and discussed in order to correlate several properties of both olives and olive oils with specific features of the cultivation area.
Giulia Vicario; Alessandra Francini; Mario Cifelli; Valentina Domenici; Luca Sebastiani. Near UV-Vis and NMR Spectroscopic Methods for Rapid Screening of Antioxidant Molecules in Extra-Virgin Olive Oil. Antioxidants 2020, 9, 1245 .
AMA StyleGiulia Vicario, Alessandra Francini, Mario Cifelli, Valentina Domenici, Luca Sebastiani. Near UV-Vis and NMR Spectroscopic Methods for Rapid Screening of Antioxidant Molecules in Extra-Virgin Olive Oil. Antioxidants. 2020; 9 (12):1245.
Chicago/Turabian StyleGiulia Vicario; Alessandra Francini; Mario Cifelli; Valentina Domenici; Luca Sebastiani. 2020. "Near UV-Vis and NMR Spectroscopic Methods for Rapid Screening of Antioxidant Molecules in Extra-Virgin Olive Oil." Antioxidants 9, no. 12: 1245.
Bee pollen is made by honey bees (Apis Mellifera) from the pollen of plants and flowers and represents an apiary product enriched in essential amino acids, polyphenols, omega-3, and omega-6 fatty acids. This study investigated the botanical origin, micronutrient profile, and antioxidant activity of bee pollen samples (n = 10) harvested in Lucca and Massa Carrara (Tuscany, Italy) between 2016 and 2017. The palynological analysis showed that bee pollen samples were composed of nine botanical families. Front-face fluorescence spectroscopy was performed on bee pollen samples in bulk, without any treatment, and in ethanol extracts to determine the characteristic fluorescent profile and, to identify the main chemical compounds with biological activity. The main chemical compounds detected were polyphenols (mainly flavonoids and phenolic acids), hydro-soluble vitamins (B2, B3, B6, and B9), amino acids, and pigments. Furthermore, the antioxidant activity was investigated, and one of the two Viburnum pollens resulted in the highest polyphenols and flavonoids content (20.15 ± 0.15 mg GAE/g fw and 23.46 ± 0.08 mg CE/g fw, respectively). However, Prunus and Eucalyptus families showed the highest in vitro (190.27 ± 8.30 µmol Fe2+/g) and ex vivo (54.61 ± 8.51 CAA unit) antioxidant capacity, respectively. These results suggested that Tuscan bee pollen, depending on the botanical family, is rich in essential nutrients and potential nutraceutical product.
Daniele Barbieri; Morena Gabriele; Martina Summa; Raffaele Colosimo; Donatella Leonardi; Valentina Domenici; Laura Pucci. Antioxidant, Nutraceutical Properties, and Fluorescence Spectral Profiles of Bee Pollen Samples from Different Botanical Origins. Antioxidants 2020, 9, 1001 .
AMA StyleDaniele Barbieri, Morena Gabriele, Martina Summa, Raffaele Colosimo, Donatella Leonardi, Valentina Domenici, Laura Pucci. Antioxidant, Nutraceutical Properties, and Fluorescence Spectral Profiles of Bee Pollen Samples from Different Botanical Origins. Antioxidants. 2020; 9 (10):1001.
Chicago/Turabian StyleDaniele Barbieri; Morena Gabriele; Martina Summa; Raffaele Colosimo; Donatella Leonardi; Valentina Domenici; Laura Pucci. 2020. "Antioxidant, Nutraceutical Properties, and Fluorescence Spectral Profiles of Bee Pollen Samples from Different Botanical Origins." Antioxidants 9, no. 10: 1001.
The pandemic COVID-19 has brought the closure of schools of all levels and all universities in Italy, since early March 2020 up to the end of the teaching period (first half of June 2020). However, almost all universities guaranteed the continuity of educational and professional courses by using several distance education modalities. The purpose of this communication is to describe how a course of History of Chemistry and Basics of Chemical Education for first-year undergraduate students was reorganized and delivered during the COVID-19 emergency and to share several considerations that might be useful for the future. Positive and negative aspects emerged during this distance education experience are finally reported.
Valentina Domenici. A Course of History of Chemistry and Chemical Education Completely Delivered in Distance Education Mode during Epidemic COVID-19. Journal of Chemical Education 2020, 97, 2905 -2908.
AMA StyleValentina Domenici. A Course of History of Chemistry and Chemical Education Completely Delivered in Distance Education Mode during Epidemic COVID-19. Journal of Chemical Education. 2020; 97 (9):2905-2908.
Chicago/Turabian StyleValentina Domenici. 2020. "A Course of History of Chemistry and Chemical Education Completely Delivered in Distance Education Mode during Epidemic COVID-19." Journal of Chemical Education 97, no. 9: 2905-2908.
Bent-core liquid crystals showing a nematic phase stable at low temperatures are very attractive for applicative purposes in view of the inherent biaxial nature of the nematic phase. In this work, a typical five-ring bent-core mesogen was investigated by means of 2H NMR spectroscopy and X-ray diffraction (XRD) methods. These techniques provide complementary information on the structural properties of the nematic phase and the average mesogen conformation: small-angle XRD reveals the presence of short-range positional order in the form of skewed cybotaxis, while a comparison of the orientational order parameters measured by wide-angle XRD and NMR provides an estimate of the molecule bend angle. In addition, 2H NMR puts in evidence the occurrence of an unexpected transition to a low-temperature tilted phase, having a crystalline or smectic-like character. The results were compared with those of previous 13C NMR investigations.
Maria Ghilardi; Fabrizio C. Adamo; Francesco Vita; Oriano Francescangeli; Valentina Domenici. Comparative 2H NMR and X-Ray Diffraction Investigation of a Bent-Core Liquid Crystal Showing a Nematic Phase. Crystals 2020, 10, 284 .
AMA StyleMaria Ghilardi, Fabrizio C. Adamo, Francesco Vita, Oriano Francescangeli, Valentina Domenici. Comparative 2H NMR and X-Ray Diffraction Investigation of a Bent-Core Liquid Crystal Showing a Nematic Phase. Crystals. 2020; 10 (4):284.
Chicago/Turabian StyleMaria Ghilardi; Fabrizio C. Adamo; Francesco Vita; Oriano Francescangeli; Valentina Domenici. 2020. "Comparative 2H NMR and X-Ray Diffraction Investigation of a Bent-Core Liquid Crystal Showing a Nematic Phase." Crystals 10, no. 4: 284.
Front-face fluorescence spectra of honey samples can be used as authentication and quality assessment method.
Erica Parri; Giulia Santinami; Valentina Domenici. Front-Face Fluorescence of Honey of Different Botanic Origin: A Case Study from Tuscany (Italy). Applied Sciences 2020, 10, 1776 .
AMA StyleErica Parri, Giulia Santinami, Valentina Domenici. Front-Face Fluorescence of Honey of Different Botanic Origin: A Case Study from Tuscany (Italy). Applied Sciences. 2020; 10 (5):1776.
Chicago/Turabian StyleErica Parri; Giulia Santinami; Valentina Domenici. 2020. "Front-Face Fluorescence of Honey of Different Botanic Origin: A Case Study from Tuscany (Italy)." Applied Sciences 10, no. 5: 1776.
Lake basins can behave as accumulators of microplastics released in wastewaters as such or resulting from degradation of larger items before and/or during their journey toward the marine environment as a final sink. A novel multianalytical approach was adopted for the detection and quantification of microplastics with size < 2 mm in the sediments of the volcanic lake of Bracciano, Italy. Simple analytical techniques such as solvent extraction/fractionation (for polyolefins and polystyrene) or depolymerization (for polyethylene terephthalate, PET), along with chromatographic detection (SEC and HPLC), allowed quantitative and qualitative determination of the main synthetic polymer contaminants. In particular, PET microplastic concentrations of 0.8–36 ppm were found, with variability related to the sampling site (exposure to incoming winds and wave action). Proton Nuclear Magnetic Resonance (1H-NMR) and Attenuated Total Reflectance Fourier Transformed InfraRed (ATR-FTIR spectroscopic investigations supported the identification and chemical characterization of plastic fragments and polymer extracts. The average molecular weight of solvent extractable polymers was evaluated from 2D 1H-NMR diffusion ordered spectroscopy (DOSY) experiments. The proposed, easily accessible multianalytical approach can be considered as a useful tool for improving our knowledge on the nature and the concentration of microplastics in sediments, giving insights on the impact of human activities on the health status of aquatic ecosystems.
Andrea Corti; Virginia Vinciguerra; Valentina Iannilli; Loris Pietrelli; Antonella Manariti; Sabrina Bianchi; Antonella Petri; Mario Cifelli; Valentina Domenici; Valter Castelvetro. Thorough Multianalytical Characterization and Quantification of Micro- and Nanoplastics from Bracciano Lake’s Sediments. Sustainability 2020, 12, 878 .
AMA StyleAndrea Corti, Virginia Vinciguerra, Valentina Iannilli, Loris Pietrelli, Antonella Manariti, Sabrina Bianchi, Antonella Petri, Mario Cifelli, Valentina Domenici, Valter Castelvetro. Thorough Multianalytical Characterization and Quantification of Micro- and Nanoplastics from Bracciano Lake’s Sediments. Sustainability. 2020; 12 (3):878.
Chicago/Turabian StyleAndrea Corti; Virginia Vinciguerra; Valentina Iannilli; Loris Pietrelli; Antonella Manariti; Sabrina Bianchi; Antonella Petri; Mario Cifelli; Valentina Domenici; Valter Castelvetro. 2020. "Thorough Multianalytical Characterization and Quantification of Micro- and Nanoplastics from Bracciano Lake’s Sediments." Sustainability 12, no. 3: 878.
The fermentation of Triticum dicoccum with sourdough enhances the nutritional aspects of the final product by the enrichment of several compounds with potential medical and biological activity, hence, could improve the health of consumers. This study analyzed the chemical composition of fermented spelt flour from Garfagnana (Province of Lucca, Tuscany) by 1H Nuclear Magnetic Resonance (1H NMR) spectroscopy and its in vitro antioxidant properties by FRAP and DPPH tests. Beyond this, the ex vivo CAA-RBC assay determined the cellular antioxidant activity on human erythrocytes under oxidative condition. Carbohydrate reduction was observed, while amino acids, organic acids and aromatic compounds with potential antioxidant activity increased during the fermentation time. Moreover, both in vitro and ex vivo outcomes showed an improved antioxidant profile. As a possible industrial application, the fermentation process adopted in this research could be reproduced on a large scale for the commercialization of the products by the food industry.
Raffaele Colosimo; Morena Gabriele; Mario Cifelli; Vincenzo Longo; Valentina Domenici; Laura Pucci. The effect of sourdough fermentation on Triticum dicoccum from Garfagnana: 1H NMR characterization and analysis of the antioxidant activity. Food Chemistry 2019, 305, 125510 .
AMA StyleRaffaele Colosimo, Morena Gabriele, Mario Cifelli, Vincenzo Longo, Valentina Domenici, Laura Pucci. The effect of sourdough fermentation on Triticum dicoccum from Garfagnana: 1H NMR characterization and analysis of the antioxidant activity. Food Chemistry. 2019; 305 ():125510.
Chicago/Turabian StyleRaffaele Colosimo; Morena Gabriele; Mario Cifelli; Vincenzo Longo; Valentina Domenici; Laura Pucci. 2019. "The effect of sourdough fermentation on Triticum dicoccum from Garfagnana: 1H NMR characterization and analysis of the antioxidant activity." Food Chemistry 305, no. : 125510.
Endothelial dysfunction has been associated to cardiovascular outcomes in patients with cardiovascular risk factors. Circulating endothelial progenitor cells (EPCs) play an important physiological role for their reparative potential of vascular integrity, but are numerically reduced and functionally impaired in patients with cardiovascular risks. This study assesses the effects of Extra Virgin Olive Oil (EVOO) and apple-enriched dark chocolate intake on the blood levels of EPCs. Methods: Thirty volunteers with cardiovascular risk factors, enrolled in a randomised, crossover, four-weeks trial, received a solid dark chocolate bar (40 g/day) containing 10% EVOO or 2.5% dry apples. Urine samples were analyzed for endogenous metabolites. Circulating EPCs levels, clinical data and anthropometric examinations were collected. 26 volunteers (M/F:14/12, 51 ± 9 years of age) completed the study. Comparison of pre-post intervention revealed a significant increase in EPCs levels associated with EVOO-dark chocolate consumption. Most biochemical parameters were not significantly modified by both chocolates. This study shows that a daily consumption of a non fattening dose of dark chocolate enriched with EVOO improves blood levels of EPCs, a well known surrogate biologic marker for endothelial function.
Francesca Felice; Alessandra Francini; Valentina Domenici; Mario Cifelli; Ester Belardinelli; Luca Sebastiani; Claudio Cantini; Rossella Di Stefano. Effects of Extra Virgin Olive Oil and Apples Enriched-Dark Chocolate on Endothelial Progenitor Cells in Patients with Cardiovascular Risk Factors: A Randomized Cross-Over Trial. Antioxidants 2019, 8, 88 .
AMA StyleFrancesca Felice, Alessandra Francini, Valentina Domenici, Mario Cifelli, Ester Belardinelli, Luca Sebastiani, Claudio Cantini, Rossella Di Stefano. Effects of Extra Virgin Olive Oil and Apples Enriched-Dark Chocolate on Endothelial Progenitor Cells in Patients with Cardiovascular Risk Factors: A Randomized Cross-Over Trial. Antioxidants. 2019; 8 (4):88.
Chicago/Turabian StyleFrancesca Felice; Alessandra Francini; Valentina Domenici; Mario Cifelli; Ester Belardinelli; Luca Sebastiani; Claudio Cantini; Rossella Di Stefano. 2019. "Effects of Extra Virgin Olive Oil and Apples Enriched-Dark Chocolate on Endothelial Progenitor Cells in Patients with Cardiovascular Risk Factors: A Randomized Cross-Over Trial." Antioxidants 8, no. 4: 88.
In this work, we report a study of two thermotropic liquid crystalline samples showing a not common mesophase behavior. The samples, namely a di-benzyloxy biphenyl derivative labelled 9/2 RS/RS, and a bimesogenic liquid crystal labelled L1, show a direct transition between two isotropic phases followed, at lower temperatures, by the optically isotropic, 3D structured, cubic phase. These systems have been investigated by means of 1H NMR diffusometry and 1H NMR relaxometry in order to characterize their isotropic–isotropic’–cubic mesophase behavior, mainly on the dynamic point of view. In particular, the temperature trend of the self-diffusion coefficients measured for both samples allowed us to significantly distinguish between the two isotropic phases, while the temperature dependence of the 1H spin-lattice relaxation time (T1) did not show significant discontinuities at the isotropic–isotropic’ phase transition. A preliminary analysis of the frequency-dependence of 1H T1 at different temperatures gives information about the main motional processes active in the isotropic mesophases.
Anton Gradišek; Mario Cifelli; Michal Wojcik; Tomaž Apih; Sergey V. Dvinskikh; Ewa Gorecka; Valentina Domenici. Study of Liquid Crystals Showing Two Isotropic Phases by 1H NMR Diffusometry and 1H NMR Relaxometry. Crystals 2019, 9, 178 .
AMA StyleAnton Gradišek, Mario Cifelli, Michal Wojcik, Tomaž Apih, Sergey V. Dvinskikh, Ewa Gorecka, Valentina Domenici. Study of Liquid Crystals Showing Two Isotropic Phases by 1H NMR Diffusometry and 1H NMR Relaxometry. Crystals. 2019; 9 (3):178.
Chicago/Turabian StyleAnton Gradišek; Mario Cifelli; Michal Wojcik; Tomaž Apih; Sergey V. Dvinskikh; Ewa Gorecka; Valentina Domenici. 2019. "Study of Liquid Crystals Showing Two Isotropic Phases by 1H NMR Diffusometry and 1H NMR Relaxometry." Crystals 9, no. 3: 178.
The colour of olive oil is due to the presence of natural pigments belonging to the class of carotenoids, chlorophylls, and their derivatives. These substances, other than being responsible for the colour, an important qualitative feature of the oil, have antioxidant and, more generally, nutraceutical properties and their quantification can be related to the product’s quality and authenticity. In this work, we have quantified the total amount of carotenoids and chlorophylls’ derivatives in several virgin and extra-virgin olive oils produced in Italy, by using two different methods that are based on near-ultraviolet-visible absorption spectroscopy. The first method defines two indexes, K670 and K470, related to absorbance values of oil at wavelengths of 670 and 470 nm, respectively. The second method is based on the mathematical deconvolution of the whole absorption spectrum of the oil to obtain the concentrations of four main pigments present in olive oils: β-carotene, lutein, pheophytin A, and pheophytin B. The concentrations of the total carotenoids and total chlorophylls’ derivatives, as obtained by the two spectroscopic methods, are compared and the results are discussed in view of the practical usefulness of spectroscopic techniques for a fast determination of pigments in olive oil.
Eleonora Borello; Valentina Domenici. Determination of Pigments in Virgin and Extra-Virgin Olive Oils: A Comparison between Two Near UV-Vis Spectroscopic Techniques. Foods 2019, 8, 18 .
AMA StyleEleonora Borello, Valentina Domenici. Determination of Pigments in Virgin and Extra-Virgin Olive Oils: A Comparison between Two Near UV-Vis Spectroscopic Techniques. Foods. 2019; 8 (1):18.
Chicago/Turabian StyleEleonora Borello; Valentina Domenici. 2019. "Determination of Pigments in Virgin and Extra-Virgin Olive Oils: A Comparison between Two Near UV-Vis Spectroscopic Techniques." Foods 8, no. 1: 18.
Bimesogenic liquid crystal elastomers, composed with controlled concentrations of two mesogenic constituents, specifically a nematogen and a smectogen, exhibit either enhanced nematic or smectic structure. Here we present a thorough examination of thermomechanical and elastic properties of such a system at high crosslinking density, with ensuing disordered smectic structure which prevents the observation of smectic-nematic phase transition by means of thermomechanical response measurements. Yet, the onset of local smectic order is clearly observable in stress-strain measurements via an anomaly in the elastic modulus. Breakdown of the local smectic structure is detected at higher mechanical loads. Bimesogen composition – temperature phase diagram is as well constructed, consistent with the one obtained by complementary experimental techniques. Stress-strain temperature dependence measurements can thus serve as efficient and simple phase diagram characterization method that is able to detect formation of smectic clusters in strongly crosslinked and thus highly disordered smecto-nematic liquid crystal elastomers.
Andraž Rešetič; Jerneja Milavec; Valentina Domenici; Blaž Zupančič; Alexey Bubnov; Boštjan Zalar. Stress-strain and thermomechanical characterization of nematic to smectic A transition in a strongly-crosslinked bimesogenic liquid crystal elastomer. Polymer 2018, 158, 96 -102.
AMA StyleAndraž Rešetič, Jerneja Milavec, Valentina Domenici, Blaž Zupančič, Alexey Bubnov, Boštjan Zalar. Stress-strain and thermomechanical characterization of nematic to smectic A transition in a strongly-crosslinked bimesogenic liquid crystal elastomer. Polymer. 2018; 158 ():96-102.
Chicago/Turabian StyleAndraž Rešetič; Jerneja Milavec; Valentina Domenici; Blaž Zupančič; Alexey Bubnov; Boštjan Zalar. 2018. "Stress-strain and thermomechanical characterization of nematic to smectic A transition in a strongly-crosslinked bimesogenic liquid crystal elastomer." Polymer 158, no. : 96-102.
An appealing property of optical diffractive structures from elastomeric materials is a possibility to regulate their optical patterns and consequently also their diffractive features with mechanical straining. We investigated the effect of strain on diffraction characteristics of holographic gratings recorded in a monodomain side-chain liquid crystalline elastomer. The strain was imposed either parallel or perpendicular to the initial alignment direction of the material. At temperatures far below the nematic–paranematic phase transition, straining along the initial alignment affects mainly the diffraction pattern, while the diffraction efficiency remains almost constant. In contrast, at temperatures close to the nematic–paranematic phase transition, the diffraction efficiency is also significantly affected. Straining in the direction perpendicular to the initial alignment strongly and diversely influences both the diffraction pattern and the diffraction efficiency. The difference between the two cases is attributed to shear–stripe domains, which form only during straining perpendicular to the initial alignment and cause optical diffraction that competes with the diffraction from the holographic grating structure.
Dejan Bošnjaković; Marko Gregorc; Hui Li; Martin Čopič; Valentina Domenici; Irena Drevenšek-Olenik. Mechanical Manipulation of Diffractive Properties of Optical Holographic Gratings from Liquid Crystalline Elastomers. Applied Sciences 2018, 8, 1330 .
AMA StyleDejan Bošnjaković, Marko Gregorc, Hui Li, Martin Čopič, Valentina Domenici, Irena Drevenšek-Olenik. Mechanical Manipulation of Diffractive Properties of Optical Holographic Gratings from Liquid Crystalline Elastomers. Applied Sciences. 2018; 8 (8):1330.
Chicago/Turabian StyleDejan Bošnjaković; Marko Gregorc; Hui Li; Martin Čopič; Valentina Domenici; Irena Drevenšek-Olenik. 2018. "Mechanical Manipulation of Diffractive Properties of Optical Holographic Gratings from Liquid Crystalline Elastomers." Applied Sciences 8, no. 8: 1330.
Several side-chain liquid single crystalline elastomers (LSCEs) were investigated by means of 2H NMR spectroscopy focusing on the temperature dependence of the spectral line width and spectral shape, as well as the T-dependence of spin–lattice and spin–spin relaxation times (T1 and T2). All measurements were performed at the Larmor frequency of 76.753 MHz for 2H. The LSCEs were prepared in the form of monodomain films by using either 2H-labelled monomers (or co-monomers), 2H-labelled cross-linkers or 2H-labelled molecular probes free to diffuse in the LSCE matrix. In all cases, deuterons are on the phenyl moiety. The main features of the measured 2H NMR properties (static and dynamic ones) in these different cases were discussed and compared with those of low-molecular-weight mesogens (i.e. the same molecules used as monomers or co-monomers in the side-chain LSCEs) in the nematic and smectic A phases. Among all investigated LSCE samples, those 2H-labelled on the cross-linker sites present distinct properties either on the 2H NMR spectral line width and spectral shape in the paranematic and in the nematic phases, which can be interpreted in terms of director reorientational dynamics in the intermediate–slow motional regime, taking into account the inherent local director misalignment of LSCEs.
Jerneja Milavec; Andraž Rešetič; Alexej Bubnov; Bostjan Zalar; Valentina Domenici. Dynamic investigations of liquid crystalline elastomers and their constituents by 2H NMR spectroscopy. Liquid Crystals 2018, 45, 2158 -2173.
AMA StyleJerneja Milavec, Andraž Rešetič, Alexej Bubnov, Bostjan Zalar, Valentina Domenici. Dynamic investigations of liquid crystalline elastomers and their constituents by 2H NMR spectroscopy. Liquid Crystals. 2018; 45 (13-15):2158-2173.
Chicago/Turabian StyleJerneja Milavec; Andraž Rešetič; Alexej Bubnov; Bostjan Zalar; Valentina Domenici. 2018. "Dynamic investigations of liquid crystalline elastomers and their constituents by 2H NMR spectroscopy." Liquid Crystals 45, no. 13-15: 2158-2173.
Liquid-crystalline elastomers (LCEs) are the object of many research investigations due to their reversible and controllable shape deformations, and their high potential for use in the field of soft robots and artificial muscles. This review focuses on recent studies about polymer composites based on LCEs and nanomaterials having different chemistry and morphology, with the aim of instilling new physical properties into LCEs. The synthesis, physico-chemical characterization, actuation properties, and applications of LCE-based composites reported in the literature are reviewed. Several cases are discussed: (1) the addition of various carbon nanomaterials to LCEs, from carbon black to carbon nanotubes, to the recent attempts to include graphene layers to enhance the thermo-mechanic properties of LCEs; (2) the use of various types of nanoparticles, such as ferroelectric ceramics, gold nanoparticles, conductive molybdenum-oxide nanowires, and magnetic iron-oxide nanoparticles, to induce electro-actuation, magnetic-actuation, or photo-actuation into the LCE-based composites; (3) the deposition on LCE surfaces of thin layers of conductive materials (i.e., conductive polymers and gold nanolayers) to produce bending actuation by applying on/off voltage cycles or surface-wrinkling phenomena in view of tunable optical applications. Some future perspectives of this field of soft materials conclude the review.
Vanessa Cresta; Giuseppe Romano; Alexej Kolpak; Boštjan Zalar; Valentina Domenici. Nanostructured Composites Based on Liquid-Crystalline Elastomers. Polymers 2018, 10, 773 .
AMA StyleVanessa Cresta, Giuseppe Romano, Alexej Kolpak, Boštjan Zalar, Valentina Domenici. Nanostructured Composites Based on Liquid-Crystalline Elastomers. Polymers. 2018; 10 (7):773.
Chicago/Turabian StyleVanessa Cresta; Giuseppe Romano; Alexej Kolpak; Boštjan Zalar; Valentina Domenici. 2018. "Nanostructured Composites Based on Liquid-Crystalline Elastomers." Polymers 10, no. 7: 773.
This study analyzed the effect of low sulfur dioxide concentrations on the chromatic properties, phytochemical composition and antioxidant activity of Aglianico red wines with respect to wines produced from conventional winemaking. We determined the phytochemical composition by spectrophotometric methods and HPLC-DAD analysis and the in vitro antioxidant activity of different wine samples by the ORAC assay. The main important classes of fluorophore molecules in red wine were identified by Front-Face fluorescence spectroscopy, and the emission intensity trend was investigated at various sulfur dioxide concentrations. Lastly, we tested the effects of both conventional and low sulfite wines on ex vivo human erythrocytes under oxidative stimulus by the cellular antioxidant activity (CAA) assay and the hemolysis test. The addition of sulfur dioxide, which has well-known side effects, increased the content of certain bioactive components but did not raise the erythrocyte antioxidant capacity.
Morena Gabriele; Chiara Gerardi; Jeannette Jacqueline Lucejko; Vincenzo Longo; Laura Pucci; Valentina Domenici. Effects of low sulfur dioxide concentrations on bioactive compounds and antioxidant properties of Aglianico red wine. Food Chemistry 2018, 245, 1105 -1112.
AMA StyleMorena Gabriele, Chiara Gerardi, Jeannette Jacqueline Lucejko, Vincenzo Longo, Laura Pucci, Valentina Domenici. Effects of low sulfur dioxide concentrations on bioactive compounds and antioxidant properties of Aglianico red wine. Food Chemistry. 2018; 245 ():1105-1112.
Chicago/Turabian StyleMorena Gabriele; Chiara Gerardi; Jeannette Jacqueline Lucejko; Vincenzo Longo; Laura Pucci; Valentina Domenici. 2018. "Effects of low sulfur dioxide concentrations on bioactive compounds and antioxidant properties of Aglianico red wine." Food Chemistry 245, no. : 1105-1112.
Public engagement becomes increasingly important for scientists. One reason is the demand of the taxpayer to know what her or his money is being spent on, and why. The other one is that in a world that increasingly relies on technology, student engagement even at a very young age becomes a target to assure the needed supply of well-educated and especially motivated scientists for the decades to come. And it falls on the older generation of current researchers to leave the comfort of their lab once in a while, to awaken the interest for science among the population. Many people may know that there is a ‘liquid crystal’ in their mobile (cell) phone display, but when prompted, no one really knows what that liquid crystal actually is, let alone how the display they use many times every day, actually works in principle. It is part of our job to change this. In this contribution Valentina Domenici and Ingo Dierking would like to report on two recent Science Festival events in which they took part, one held in Genoa, Italy, and the other in Manchester, UK.
Valentina Domenici; Ingo Dierking. Science for the small and the tall, the young and the old. Liquid Crystals Today 2018, 27, 2 -6.
AMA StyleValentina Domenici, Ingo Dierking. Science for the small and the tall, the young and the old. Liquid Crystals Today. 2018; 27 (1):2-6.
Chicago/Turabian StyleValentina Domenici; Ingo Dierking. 2018. "Science for the small and the tall, the young and the old." Liquid Crystals Today 27, no. 1: 2-6.