Acid cleaning and passivation of power plant condensers and desalination plants

Experiences of acid cleaning and passivation treatments of copper alloy tubes are described. The suitability of corrosion monitoring to follow each step of such operation is demonstrated.     

Investigation of the potential of asymptotic homogenization for elastic composites via a three-dimensional computational study

Asymptotic homogenization is employed assuming a sharp length scale separation between the periodic structure (fine scale) and the whole composite (coarse scale). A classical approach yields the linear elastic-type coarse scale model, where the effective elastic coefficients are computed solving fine scale periodic cell problems. We generalize the existing results by considering an arbitrary number of subphases and general periodic cell shapes. We focus on the stress jump conditions arising in the cell problems and explicitly compute the corresponding interface loads. The latter represent a key driving force to obtain nontrivial cell problems solutions whenever discontinuities of the coefficients between the host medium (matrix) and the subphases occur. The numerical simulations illustrate the geometrically induced anisotropy and foster the comparison between asymptotic homogenization and well established Eshelby based techniques. We show that the method can be routinely implemented in three dimensions and should be applied to hierarchical hard tissues whenever the precise shape and arrangement of the subphases cannot be ignored. Our numerical results are benchmarked exploiting the semi-analytical solution which holds for cylindrical aligned fibers.     

Light and Strong SiC Networks

The directional freezing of microfiber suspensions is used to assemble highly porous (porosities ranging between 92% and 98%) SiC networks. These networks exhibit a unique hierarchical architecture in which thin layers with honeycomb‐like structure and internal strut length in the order of 1–10 μm in size are aligned with an interlayer spacing ranging between 15 and 50 μm. The resulting structures exhibit strengths (up to 3 MPa) and stiffness (up to 0.3 GPa) that are higher than aerogels of similar density and comparable to other ceramic microlattices fabricated by vapor deposition. Furthermore, this wet processing technique allows the fabrication of large‐size samples that are stable at high temperature, with acoustic impedance that can be manipulated over one order of magnitude (0.03–0.3 MRayl), electrically conductive and with very low thermal conductivity. The approach can be extended to other ceramic materials and opens new opportunities for the fabrication of ultralight structures with unique mechanical and functional properties in practical dimensions.     

Noise evolution along optically amplified links in presence ofnonlinear parametric gain

With a semiclassical model of the optical amplifier, we calculate the evolution of noise along optically amplified lines in presence of nonlinear interaction between signal and amplified spontaneous emission, amplifier saturation, fiber dispersion and vacuum field fluctuations associated with attenuation of the fiber. The noise figure (NF) is calculated for two representative cases of long and short-distance links with different numbers of optical amplifiers and for several fiber dispersions. Results indicate that the optimum number of optical amplifiers is limited by the increase of nonlinear effects with signal power     

Effect of optical feedback on 60-GHz colliding-pulse semiconductor mode-locked lasers

We have experimentally investigated on the effects of optical feedback on the performance of monolithic colliding-pulse passively mode-locked semiconductor lasers operating at 60 GHz, designed to be efficient sources of millimeter-wave electrical signals. The characteristics of the optical-to-electrical converted signal are investigated for a long and a short external cavity by means of an external photodiode and by using the saturable absorber of the device as an intracavity photodetector. For a power feedback ratio larger than 10/sup -3/, the linewidth of the millimeter-wave signal is severely broadened with respect to the value of 230 kHz measured in unperturbed conditions. We also report that optical feedback causes central frequency shift and instability, and a reduction of the useful colliding-pulse mode-locked operating region in the biasing parameters of the device.     

Multivariate statistical integration of Satellite infrared and microwave radiometric measurements for rainfall retrieval at the geostationary scale

The objective of this paper is to investigate how the complementarity between low earth orbit (LEO) microwave (MW) and geostationary earth orbit (GEO) infrared (IR) radiometric measurements can be exploited for satellite rainfall detection and estimation. Rainfall retrieval is pursued at the space-time scale of typical geostationary observations, that is at a spatial resolution of few kilometers and a repetition period of few tens of minutes. The basic idea behind the investigated statistical integration methods follows an established approach consisting in using the satellite MW-based rain-rate estimates, assumed to be accurate enough, to calibrate spaceborne IR measurements on sufficiently limited subregions and time windows. The proposed methodologies are focused on new statistical approaches, namely the multivariate probability matching (MPM) and variance-constrained multiple regression (VMR). The MPM and VMR methods are rigorously formulated and systematically analyzed in terms of relative detection and estimation accuracy and computing efficiency. In order to demonstrate the potentiality of the proposed MW-IR combined rainfall algorithm (MICRA), three case studies are discussed, two on a global scale on November 1999 and 2000 and one over the Mediterranean area. A comprehensive set of statistical parameters for detection and estimation assessment is introduced to evaluate the error budget. For a comparative evaluation, the analysis of these case studies has been extended to similar techniques available in literature.     

Ficolin-2 Plasma Level Assesses Liver Fibrosis in Non-Alcoholic Fatty Liver Disease

Fibrosis is the strongest predictor for disease-specific mortality in non-alcoholic fatty liver diseases (NAFLD), but the need for liver biopsy limits its diagnosis. We assessed the performance of plasma ficolin-2 (FCN-2) as a biomarker of fibrosis identified by an in silico discovery strategy. Two hundred and thirty-five morbidly obese (MO) subjects with biopsy-proven NAFLD stratified by fibrosis stage (F0, n = 44; F1, n = 134; F2, n = 46; F3/F4, n = 11) and 40 cirrhotic patients were enrolled. The cohort was subdivided into discovery (n = 76) and validation groups (n = 159). The plasma level of FCN-2 and other candidate markers was determined. FCN-2 was inversely correlated with the stage of liver fibrosis (ρ = −0.49, p < 0.001) independently of steatosis (p = 0.90), inflammation (p = 0.57), and ballooning (p = 0.59). In the global cohort, FCN-2 level decreased significantly in a stepwise fashion from F0/F1 (median 4753 ng/mL) to F2–F3–F4 (2760 ng/mL) and in cirrhotic subjects (1418 ng/mL). The diagnostic performance of FCN-2 in detecting F ≥ 2 was higher than other indexes (APRI, FIB-4) (AUROC 0.82, 0.68, and 0.6, respectively). The accuracy improved when combined with APRI score and HDL values (FCNscore, AUROC 0.85). Overall, the FCN-2 plasma level can accurately discriminate liver fibrosis status (minimal vs. moderate/advanced) significantly improving the fibrosis diagnostic algorithms.     

Internal structure of bitumen/polymer/wax ternary mixtures for warm mix asphalts

Polymer modified asphalts (PMA) and warm mix asphalts (WMA) are technologies widely adopted in the paving industry. The first one is well established, while the second one is relatively new, but rapidly growing since it guarantees economic and environmental advantages. Until now PMA and WMA have been used disjointedly, but it would be useful to combine them to keep the advantages of both. One of the adopted solutions to obtain a warm effect is the addition of waxes to the asphaltic binder. Therefore, a “warm mix polymer modified asphalt” may be potentially obtained with a ternary asphalt/polymer/wax system. However, the final warm effect and performances of the binder will depend on the interactions between the three components. A preliminary investigation was done by mixing asphalt, styrene‐butadiene‐styrene block copolymer and a wax chosen among the following three categories: paraffinic, partially oxidized and maleic anhydride functionalized. The morphological and calorimetric analyses and solubility tests allowed identifying different behaviors depending on the wax type, which may preferentially interact either with the asphalt or with the polymer, thus influencing the whole binder structure. With regard to the ternary mixes, it was found that: (i) the paraffinic wax preferentially resides in the polymer‐rich phase, and slightly enhances the asphalt‐polymer compatibility; (ii) the partially oxidized wax prefers the asphaltene‐rich phase and reduces the compatibility; (iii) it is not clear where the functionalized wax is located, but it has a considerable compatibilizing effect and strongly alters the colloidal equilibrium of the asphalt‐polymer blend. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Thyroid Hormones and Antioxidant Systems: Focus on Oxidative Stress in Cardiovascular and Pulmonary Diseases

In previous works we demonstrated an inverse correlation between plasma Coenzyme Q₁₀ (CoQ₁₀) and thyroid hormones; in fact, CoQ₁₀ levels in hyperthyroid patients were found among the lowest detected in human diseases. On the contrary, CoQ₁₀ is elevated in hypothyroid subjects, also in subclinical conditions, suggesting the usefulness of this index in assessing metabolic status in thyroid disorders. A Low-T3 syndrome is a condition observed in several chronic diseases: it is considered an adaptation mechanism, where there is a reduction in pro-hormone T4 conversion. Low T3-Syndrome is not usually considered to be corrected with replacement therapy. We review the role of thyroid hormones in regulation of antioxidant systems, also presenting data on total antioxidant capacity and Coenzyme Q₁₀. Published studies suggest that oxidative stress could be involved in the clinical course of different heart diseases; our data could support the rationale of replacement therapy in low-T3 conditions.