Materials for Photonic Applications From Sol-Gel*

A review of sol-gel materials developed in our laboratory for photonic applications is presented. These materials include planar and strip waveguides for integrated optics (IO) passive devices, Er doped waveguides for IO amplifiers, films doped with semiconductor quantum dots for optical switching and fullerene doped materials for optical limiting.     

Adsorption of H2 on Alkali Metal Substrates

Adsorption of H₂ on Li and Cs substrates at low temperature is investigated theoretically by means of Density Functional and Path Integral Monte Carlo calculations. Qualitative and semi-quantitative agreement is observed between the two methods. Adsorption on Li is observed to occur through completion of successive solid layers, whereas resugts for a Cs substrate are consistent with absence of wetting at low temperature.     

Control of Wave Propagation in Sandwich Plate Rows with Periodic Honeycomb Core

The wave propagation in sandwich plate rows with cellular core is analyzed and controlled. Honeycomb core materials of different geometry placed periodically along the structure introduce the proper impedance mismatch necessary to obstruct the propagation of waves over specified frequency bands (stop bands). The location and the extension of the stop bands can be optimized by proper selection of the geometrical and physical properties of the core. An optimal configuration of the core can be identified to design passive sandwich structures, which are stable and quiet over desired frequency bands. A theoretical model is developed to describe the wave propagation characteristics and the vibrations of a three-layered sandwich plate simply supported along its longitudinal edges. The core properties of the plate change periodically along the plate length. The wave propagation characteristics are estimated by analyzing the transfer matrix of each cell of the resulting periodic structure. The transfer matrix is also properly recast to obtain the cell’s dynamic stiffness matrix and to formulate a spectral finite element model for the periodic sandwich plate. The spectral finite element model allows predicting the dynamic behavior of the structure with a significantly reduced number of elements as compared to conventional finite elements. The numerical model is used to predict the dynamic response of the considered class of plates and to study their propagation and attenuation characteristics for various core configurations. The presented numerical results demonstrate the simplicity and the effectiveness of the proposed treatment, which reduces the transmission of waves and the plate vibrations over specified frequency bands without the need of additional passive or active control devices. Such unique characteristics can be employed to design lightweight composite panels behaving as mechanical filters. The filtering capabilities of such passive composite panels can be properly modified and optimized to fit required transmissibility levels over desired frequencies without compromising the size and the weight of the structure.     

A game theory simulator for assessing the performances of competitive electricity markets

In the last years, electricity markets were created all over the world following different basis concepts. Market structure, market rules, demand levels, market concentration and energy sources to produce electricity have a strong influence on market performances. Modifications on these aspects may significantly affect market outcomes. Sensitivity analyses need proper simulation tools. In this paper a medium run electricity market simulator (MREMS) based on game theory is presented. This simulator incorporates two different games, one for the unit commitment of thermal units and one for strategic bidding and hourly market clearing. Either a Forchheimer (one leader) or Bertrand (all player are leaders) or even intermediate model with a whatever number of leaders can be selected, in dependence on the strategic behavior of the producers, allowing for the simulation of markets with different levels of concentration. The simulator was applied to analyse producers’ behavior during the first operative year of the Italian power exchange. A comparison between simulation and true market results was carried out in order to test the simulator and validate its simplifying hypotheses. MREMS, yet capable to be used stand-alone, was conceived as the heart of a long-term market simulator (LREMS) allowing to simulate the long-run evolution of the generation park (investments in new plants, refurbishment and dismission of older ones). LREMS is a hierarchic simulator: a long-term “outer” game takes yearly investment decisions based on mid-term price projections provided by MREMS. Although this paper is mainly devoted to describe MREMS, one specific section will provide an overview of the “outer” game implemented by LREMS.     

Monitoring Somatic Genetic Alterations in Circulating Cell-Free DNA/RNA of Patients with “Oncogene-Addicted” Advanced Lung Adenocarcinoma: A Real-World Clinical Study

Liquid biopsy has advantages over tissue biopsy, but also some technical limitations that hinder its wide use in clinical applications. In this study, we aimed to evaluate the usefulness of liquid biopsy for the clinical management of patients with advanced-stage oncogene-addicted non-small-cell lung adenocarcinomas. The investigation was conducted on a series of cases—641 plasma samples from 57 patients—collected in a prospective consecutive manner, which allowed us to assess the benefits and limitations of the approach in a real-world clinical context. Thirteen samples were collected at diagnosis, and the additional samples during the periodic follow-up visits. At diagnosis, we detected mutations in ctDNA in 10 of the 13 cases (77%). During follow-up, 36 patients progressed. In this subset of patients, molecular analyses of plasma DNA/RNA at progression revealed the appearance of mutations in 29 patients (80.6%). Mutations in ctDNA/RNA were typically detected an average of 80 days earlier than disease progression assessed by RECIST or clinical evaluations. Among the cases positive for mutations, we observed 13 de novo mutations, responsible for the development of resistance to therapy. This study allowed us to highlight the advantages and disadvantages of liquid biopsy, which led to suggesting algorithms for the use of liquid biopsy analyses at diagnosis and during monitoring of therapy response.     

The Fluid Joint: The Soft Spot of Micro‐ and Nanosystems

Fluid bridges are ubiquitous soft structures of finite size that conform to and link the surfaces of neighboring objects. Fluid joints, the specific type of fluid bridge with at least one extremity constrained laterally, display even more pronounced reactivity and self‐restoration, which make them remarkably suited for assembly, actuation, and manipulation purposes. Their peculiar surface and bulk properties place fluid joints at the rich intersection of diverse scientific interests, and foster their widespread use throughout micro‐ and nanotechnology. A critical survey of the mechanics and of the manifold applications of fluid bridges and joints in micro‐ and nanosystems is presented here, along with current challenges and multidisciplinary perspectives.     

Stable and non-competitive association of Saccharomyces cerevisiae, Candida milleri and Lactobacillus sanfranciscensis during manufacture of two traditional sourdough baked goods

The microbiota occurring in all the manufacturing phases of two Italian sourdough sweet-leavened baked goods (a typical Genoese dry biscuit, Lagaccio, and a soft stuffed North Italian typical cake, Panettone) were investigated over a period of three years. The two sourdough mother sponges were characterized by the stable presence of three dominant microbial species in potential competition for carbohydrates: Lactobacillus sanfranciscensis, Candida milleri, and Saccharomyces cerevisiae. Genotypic and phenotypic characterizations of microbial isolates pointed out that each mother sponge harbored its own strains, well distinguishable by molecular methods of analysis but not differing in their main metabolic properties from those known for the corresponding species. The microbial and biochemical evolution during the whole production protocol of both manufactures demonstrated that the three microbial species grew at almost the same growth rates, without exhausting any of the main carbon substrates (maltose, glucose and fructose). The quite similar growth dynamics under practical conditions and the constant presence of all fermentable carbohydrates were recognized as responsible for the stable non competitive association of maltose-positive and maltose-negative species in both sourdoughs. However, the two sourdoughs were characterized by quite different LAB to yeast ratio, with values significantly higher in Panettone than in Lagaccio. The cause of this difference could mainly be ascribed to the temperature of the mother sponge regeneration phase, that, in the case of Panettone manufacture, occurred under conditions of moderate refrigeration.     

The Application of NIR FT-Raman Spectroscopy to Monitor Starch Retrogradation and Crumb Firmness in Semolina Bread

In this study, the potential application of near-infrared (NIR) Fourier-transform (FT)-Raman spectroscopy to monitor starch retrogradation in stored bread crumb was investigated. Semolina-based bread was made and cut into slices, which were stored under controlled conditions in sealed plastic bags. The aging of the bread crumb was monitored by both NIR FT-Raman spectroscopy and a texture analysis over a period of 20 days. Two-dimensional correlation analysis in the spectral range of 390–975 cm⁻¹ revealed characteristic differences among the spectra collected over time for bands that peaked at 480, 765, and 850 cm⁻¹. The band at 480 cm⁻¹ is studied here in detail. During the storage, the peak frequency of this band shifted towards lower wavenumbers, and its full width at half height decreased. Both of these parameters are highly correlated (R ² = 0.921 and R ² = 0.949, respectively) to crumb hardness measured by the texture analyzer.