PMMA/o‐MMT nanocomposites obtained using thermally stable surfactants

In the preparation of polymer/montmorillonite (MMT) nanocomposites, the commonly used compatibilizers (cations of long carbon‐chain alkyl ammonium salts) present the drawback of a poor thermal stability. During bulk processing of nanocomposites elevated temperatures are usually required and, if processing temperature is close to decomposition temperature of the surfactant, decomposition will occur altering the interface between filler and polymer. To solve this problem, organically modified MMTs with thermally stable imidazolium surfactants have been prepared. A series of nanocomposites were obtained by dispersing o‐MMT in poly(methyl methacryate) (PMMA) matrix via an in situ free radical polymerization. The nanocomposites were characterized by X‐ray diffraction, transmission electron microscopy, gel permeation chromatography, thermogravimetric analysis, dynamic mechanical analysis, and nanoindentation measurements. The results showed that nanocomposite thermal stability depended on both the kind of used surfactant and degree of exfoliation. Under the same values of molecular weight, the nanocomposites containing imidazolium cations showed a better thermal stability with respect to the nanocomposite obtained using a standard alkylammonium surfactant. Dynamic mechanical and Nanoindentation measurements showed an improvement of mechanical properties, such as modulus and hardness, with respect to pure PMMA. Solution blending treatments on these nanocomposites led to obtaining of further improvement of the thermal performance. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41393.     

Evolution of porosity in the high-burnup fuel structure

The evolution of the high-burnup structure (HBS) porosity is investigated. Electron probe microanalysis (EPMA) and scanning electron microscope (SEM) measurements of UO₂ fuel with ≈105 GWd/tHM rod average burnup show the formation of an ultra-high burnup structure with a local burnup of 300 GWd/tHM in the proximity of the fuel-cladding interface. Such structure is characterized by gas pores of sizes up to 15 μm. A large population of pores with 3-5 μm pores is also observed in more inner regions of the HBS. An analysis of the pore size distributions indicates predominance of 3.5 μm and 7.5 μm pores. A simple model accounting for vacancy diffusion kinetics and coalescence is used to interpret the observations: the 3.5 μm pores are obtained by growth of 1 μm pores with an initial overpressurization of 50-70 MPa. The extra-large pores with diameters ≈7-8 μm result by coalescence of the intermediate size pores, assuming that: (1) such pores are only slightly overpressurized and that (2) the coalescence process occurs at constant porosity, as observed experimentally.     

Large Scale Probabilistic Drought Characterization Over Europe

A reliable assessment of drought return periods is essential to help decision makers in setting effective drought preparedness and mitigation measures. However, often an inferential approach is unsuitable to model the marginal or joint probability distributions of drought characteristics, such as drought duration and accumulated deficit, due to the relatively limited number of drought events that can be observed in the historical records of the hydrological variables of interest. As an alternative, the marginal and multivariate probability cdf’s of drought characteristics can be derived as functions of the parameters of the cdf of the underlying variable (e.g. precipitation), whose sample series is usually long enough to obtain trustworthy estimates in a statistical sense. In this study, the latter methodology is applied to investigate space-time variability of drought occurrences over Europe by using the CRU TS3.10.01 precipitation dataset for the period 1901–2009. In particular, a methodology able to take into account autocorrelation in the underlying precipitation series is adopted. First, a spatial analysis of historical droughts at European level is carried out. Then, the joint probability distributions of drought duration and accumulated deficit are derived for each cell, with reference to both historical and design drought events. Finally, the corresponding bivariate drought return periods are computed, as the expected values of the interarrival time between consecutive critical droughts.Results show that several heavy drought episodes have widely affected the continent. Among the most recent events, drought occurred during the period 1985–1995 was the worst in terms of extent of the regions characterized by return periods greater than 250 years. Besides Euro-Mediterranean regions, North Western and Central Eastern regions appear more drought prone than the rest of Europe, in terms of low values of return periods.     

WONDER: A resilient WDM packet network for metro applications

This paper presents the architecture of a Wavelength Division Multiplexing (WDM) optical packet network, called WONDER, that was designed and prototyped in the PhotonLab at Politecnico di Torino, Italy. The design and implementation of the WONDER network aim to assess the effectiveness of optical technologies with respect to electronic ones, trying to identify an optimal mix of the two technologies. The architecture shows interesting resilience properties that enable the design of fast fault-recovery schemes. In this paper, we present the physical topology and node structure of the prototype, and discuss the implementation and performance of a fault-recovery algorithm.     

Lactone monomers obtained by enzyme catalysis and their use in reversible thermoresponsive networks

Enzyme-catalyzed transformations have a great potential in both the pharmaceutical and chemical industry to achieve complex and (stereo)selective synthesis under mild reaction conditions. Still, the implementation of biocatalysis in the prerequisite upgrading of inert synthons into activated monomers for polymer applications has not yet been fully realized. In this contribution, we show that scaled-up synthesis of bicyclic norcamphor lactone using an engineered Baeyer–Villiger monooxygenase (BVMO) is feasible to reach complete conversion of the corresponding ketone in 24 h in shake-flask. The lactone monomer obtained by enzyme catalysis was copolymerized with ε-caprolactone via ring-opening polymerization to study the impact of the additional ring on material properties. Moreover, four-arm star-like, homo and block copolymers were designed from ε-caprolactone, ε-decalactone, and norcamphor lactone and characterized for their structural and thermal properties. These newly explored macromolecules were functionalized with furan rings using the enzyme Candida antarctica lipase B which allowed the formation of thermolabile networks via the pericyclic reaction with bismaleimide by means of Diels–Alder chemistry. The bonding/debonding state of these star-like based materials can be tuned by a suitable selection of thermal treatment. The temperature-dependent reversibility was assessed by thermal analysis and solubility test. Our results presented here shed light on the high potential of the use of chemoenzymatic approaches in the synthesis of new functional materials with tuned physiochemical properties. © 2020 The Authors. Journal of Applied Polymer Science published by Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48949.     

Lincomycin solar photodegradation, algal toxicity and removal from wastewaters by means of ozonation

Antibiotic molecules have been reported among the xenobiotics present at trace levels in sewage treatment plant (STP) effluents and aquatic environment. Lincomycin, one of the most used in clinical practices whose presence in the STP effluents has been often documented, is submitted to an extensive investigation to assess its persistence in the environment and toxicity towards different algal strains. The possibility to remove the lincomycin from water by means of ozonation is demonstrated and a reduction of toxicity of ozonated solutions on S. leopoliensis, with respect to untreated solutions containing this compound, is obtained even just for 1h of treatment. Kinetic constants for the attack to lincomycin of ozone (from 1.53 x 10(5) M(-1)s(-1) at pH = 3.0 and 4.93 x 10(5) M(-1)s(-1) at pH = 6.7) and OH radicals (4.37 x 10(9) M(-1)s(-1) at pH = 5.5 and 4.59 x 10(9) M(-1)s(-1) at pH = 7.5) are also evaluated.     

A non-parametric segmentation methodology for oral videocapillaroscopic images

We aim to describe a new non-parametric methodology to support the clinician during the diagnostic process of oral videocapillaroscopy to evaluate peripheral microcirculation. Our methodology, mainly based on wavelet analysis and mathematical morphology to preprocess the images, segments them by minimizing the within-class luminosity variance of both capillaries and background. Experiments were carried out on a set of real microphotographs to validate this approach versus handmade segmentations provided by physicians. By using a leave-one-patient-out approach, we pointed out that our methodology is robust, according to precision–recall criteria (average precision and recall are equal to 0.924 and 0.923, respectively) and it acts as a physician in terms of the Jaccard index (mean and standard deviation equal to 0.858 and 0.064, respectively).     

Automatic Tuning Architecture for the Navigation Control Loops of Unmanned Aerial Vehicles

One of the most time consuming phases in the development of an Unmanned Aerial Vehicle is the tuning of the control algorithms. In this paper the hardware and software suite developed for the self-tuning of the control loops of unmanned flying platforms is presented. The VOLCAN UAV has been used as platform to test and validate the developed architecture. The simplified control system of the VOLCAN UAV is described, together with the Graphical User Interface that allows the rapid automatic tuning of the system by means of Åström and Hägglund’s method. The Hardware in the Loop architecture used to test both the control algorithms and the tuning procedure is presented in the final part of the paper, together with the obtained experimental results.     

赛乔·罗西品牌店

客户:赛乔·罗西,Wallpaper~*杂志项目地点:意大利,米兰开业时间:2010年4月14日面积:60平方米摄影:Antonino CardilloClient:Sergio Rossi and Wallpaper~*MagazineAddress:via Ponte Vetero 19,Milan,ItalyConstruction time:ten daysOpening day:14th April.2010Surface:60m~2Photographer:Antonino Cardillo