Photoinduced interfacial electron transfer and lateral charge transport in molecular donor-acceptor photovoltaic systems

Nanostructured liquid/solid and solid/solid bulk heterojunctions designed for the conversion of solar energy offer ideal models for the investigation of light-induced ET dynamics at surfaces. Despite significant study of processes leading to charge generation in third-generation solar cells, a conclusive picture of the photophysics of these photovoltaic converters is still missing. More specifically searched is the link between the molecular structure of the interface and the kinetics of surface photoredox reactions. Fundamental scientific issues in this field are addressed by the research project undertaken in the frame of the NCCR MUST endeavor, an outline of which is given here.     

Characterization of Mesenchymal Stem Cell Differentiation within Miniaturized 3D Scaffolds through Advanced Microscopy Techniques

Three-dimensional culture systems and suitable substrates topographies demonstrated to drive stem cell fate in vitro by mechanical conditioning. For example, the Nichoid 3D scaffold remodels stem cells and shapes nuclei, thus promoting stem cell expansion and stemness maintenance. However, the mechanisms involved in force transmission and in biochemical signaling at the basis of fate determination are not yet clear. Among the available investigation systems, confocal fluorescence microscopy using fluorescent dyes enables the observation of cell function and shape at the subcellular scale in vital and fixed conditions. Contrarily, nonlinear optical microscopy techniques, which exploit multi-photon processes, allow to study cell behavior in vital and unlabeled conditions. We apply confocal fluorescence microscopy, coherent anti-Stokes Raman scattering (CARS), and second harmonic generation (SHG) microscopy to characterize the phenotypic expression of mesenchymal stem cells (MSCs) towards adipogenic and chondrogenic differentiation inside Nichoid scaffolds, in terms of nuclear morphology and specific phenotypic products, by comparing these techniques. We demonstrate that the Nichoid maintains a rounded nuclei during expansion and differentiation, promoting MSCs adipogenic differentiation while inhibiting chondrogenesis. We show that CARS and SHG techniques are suitable for specific estimation of the lipid and collagenous content, thus overcoming the limitations of using unspecific fluorescent probes.     

Mercury in fish: concentration vs. fish size and estimates of mercury intake.

Total mercury concentrations were determined in different fish size classes of commercial importance such as, conger eel (Conger conger), starry ray (Raja asterias), forkbeard (Phycis blennoides), frostfish (Lepidopus caudatus), striped mullet (Mullus barbatus), red gurnard (Aspitrigla cuculus) and yellow gurnard (Trigla lucerna) in order to evaluate variations in consumer exposure to mercury as a function of fish consumption of a spectrum of different sizes. The highest mean levels of total mercury were detected in conger eel (0.80 microg g(-1)) and starry ray (0.75 microg g(-1)). Forkbeard (0.67 microg g(-1)), frostfish (0.59 microg g(-1)) and striped mullet (0.55 microg g(-1)) showed slightly lower levels, while red gurnard (0.33 microg g(-1)) and yellow gurnard (0.22 microg g(-1)) exhibited the lowest concentrations. The results of linear regression analysis showed a significant relationship between mercury concentrations and fish size for all species. Consequently, dietary consumption of larger size specimens leads to an increase in the exposure level for consumers. Understanding by consumers of all factors leading to an increase of exposure to mercury is the first step to enable them to make decisions about eating fish.     

Modelling the evolution of oxidative browning during storage of white wines: effects of packaging and closures

Shelf life of products is a key parameter for any company at local and international level that wish to improve their competitiveness; thus, there is a need to search for methods that allow one to predict the shelf life of bottled wines. In this view, the progress of chemical oxidative reactions of six Italian white wines during storage (10 months after bottling), in different packaging, was monitored by means of selected oenological parameters. The optical density at 420 nm, an index of browning, showed a progressive increase that fitted the zero‐order kinetic rate. The onset of wine browning was further tested by means of accelerated ageing in controlled temperature conditions which results, modelled using the rate constants approach, showed an Arrhenius‐like dependence from temperature, allowing to estimate apparent activation energies of oxidative chemical browning (range: 46.8–88.3 kJ mol^?1). Kinetic and thermodynamic approach provided a useful tool to predict quality changes of white wines during storage with respect to packaging conditions.     

Postharvest stilbenes and flavonoids enrichment of table grape cv Redglobe (Vitis vinifera L.) as affected by interactive UV-C exposure and storage conditions

Flavonoids and stilbenes are secondary metabolites produced in plants that can play an important health-promoting role. The biosynthesis of these compounds generally increases as a response to biotic or abiotic stress; therefore, in order to achieve as high phenolic accumulation as possible, the interactive effects of storage conditions (temperature and time) and UV-C radiation on polyphenols content in postharvest Redglobe table grape variety were investigated. During a storage time longer than 48 h, both cold storage (4 °C) and UV-C exposure of almost 3 min (2.4 kJ m⁻²) positively enhanced the content of cis- and trans-piceid (34 and 90 μg g⁻¹ of skin, respectively) together with quercetin-3-O-galactoside and quercetin-3-O-glucoside (15 and 140 μg g⁻¹ of skin, respectively) up to three fold respect to control grape samples. Conversely, catechin was not significantly affected by irradiation and storage treatments. With regard anthocyanins, the highest concentrations of cyanidin-3-O-glucoside and peonidin-3-Oglucoside were observed in Redglobe, stored at both room temperature and 4 °C, after 5 min (4.1 kJ m⁻²) of UV-C treatment and 24 h of storage. Gathered findings showed that combined postharvest treatments can lead to possible “functional” grapes, within normal conditions of market commercialization, responding to the rising consumers demand to have foods that support and promote health.     

Integrated simulation–optimisation of pull control systems

Pull policies are considered to be among the most efficient control strategy. Setting the correct parameters to maximise their efficiency is, however, not a trivial task. Simulation–optimisation techniques have received particular attention as a means to solve this problem. Nevertheless, they require the iterative solution of an optimisation model to generate the parameter values and a discrete event simulator to evaluate the resulting system performance. In the framework of simulation-optimisation, this paper proposes a combined solution of the optimisation and simulation problems for the optimal operation of pull control systems under several control strategies. Numerical experiments were performed to evaluate the performance of the proposed technique.