Flexible, low-density polymer crosslinked silica aerogels

Polymerization of a di-isocyanate with the amine-modified surface of a sol-gel derived mesoporous silica network crosslinks the nanoparticles of the silica skeleton, and reinforces the otherwise fragile framework. Systematically adjusting the processing variables affecting density produce aerogels whose macroscopic properties could be controlled, and are attributed to changing nanoscale morphology. Aerogels crosslinked using the smallest amount of silica studied exhibit as much as a 40-fold increase in strength over the corresponding non-crosslinked framework, and are flexible.     

A fuzzy-logic based optical sensor for online weld defect-detection

This paper describes an intelligent optical sensor for real time defect detection in gas metal arc welding processes. The sensor measures the radiations emitted by the plasma surrounding the welding arc, and analyzes the information in real time to determine an index of local quality of the weld. The data processing algorithm encompasses a Kalman filter to reduce the heavy amount of noise affecting the measured signals, and an intelligent fuzzy system to assess the degree of acceptability of the weld. The fuzzy system is also able to detect the risk of specific problems (e.g., anomalies in the current, voltage or speed of the arc, contamination with other materials, holes) and the position of defects along the welding line. In an extensive experimental comparison, the fuzzy system outperforms a former version of the detection algorithm based on a statistical approach.     

Analysis of virologic and immunologic events in HIV infection

A number of pathogenic events occurring immediately after the transmission of HIV lead to the establishment of chronic infection. In fact, despite the detection of vigorous virus-specific immune responses during primary infection, HIV is able to establish chronic infection in most of the cases. This is the result of several virologic and immunologic mechanisms that HIV has evolved to escape and/or to weaken virus-specific immune responses. Lymphoid organs represent the primary anatomic site for the establishment of chronic infection, and if highly active antiretroviral therapy is not initiated in early stage disease, there is a progressive destruction of lymphoid tissue that ultimately leads to the profound immunosuppression typical of AIDS. Therefore, analysis of lymphoid organs is crucial for the correct evaluation of the effectiveness of antiretroviral therapy in HIV infection.     

Reduced Models for Efficient CCS Verification

Verification of a concurrent system can be accomplished by model checking the properties on a structure representing the system; this structure is, in general, a transition system which contains a prohibitive number of states. In this paper, we apply a method to reduce the state explosion problem by pointing out the events of the system to be ignored on the basis of the property to be verified. We evaluate the method by means of a real application used as a case study: the system is specified by a CCS program, then the program is reduced by means of syntactic rules; afterwards, the corresponding transition system is built by means of a non-standard operational semantics, which performs further reductions during the construction. Prototype tools perform both kinds of reductions; finally the required properties are checked by means of the model checkers of the CWB-NC.     

Detection of lead in Zea mays by dual‐energy X‐ray microtomography at the SYRMEP beamline of the ELETTRA synchrotron and by atomic absorption spectroscopy

This study is related to the application of the X‐ray dual‐energy microradiography technique together with the atomic absorption spectroscopy (AAS) for the detection of lead on Zea mays stem, ear, root, and leaf samples. To highlight the places with lead intake, the planar radiographs taken with monochromatic X‐ray radiation in absorption regime with photon energy below and above the absorption edge of a given chemical element, respectively, are analyzed and processed. To recognize the biological structures involved in the intake, the dual‐energy images with the lead signal have been compared with the optical images of the same Z. mays stem. The ear, stem, root, and leaf samples have also been analyzed with the AAS technique to measure the exact amount of the hyperaccumulated lead. The AAS measurement revealed that the highest intake occurred in the roots while the lowest in the maize ears and in the leaf. It seems there is a particular mechanism that protects the seeds and the leaves in the intake process. Microsc. Res. Tech., 2010. © 2009 Wiley‐Liss, Inc. This article was published online on 1 December 2009. An error was subsequently identified. This notice is included in the online and print version to indicate that both have been corrected 19 February 2010.     

Isolation and catalytic actions of polyphenoloxidase from sunflower seeds (Helianthus annuus)

In the last few decades, biotechnological applications of phenoloxidase enzymes have become an area of significant interest. In this study, sunflower seeds, seedlings and defatted mill cake were investigated as possible plant source of polyphenoloxidase (PPO). Noticeable variation of chlorogenic acid concentration in each raw material has undoubtedly proven that only sunflower seedlings have significant amounts of active PPO. The activity of the enzymes was assessed by measuring the molar decrease of caffeic acid. Isolated protein powders from each raw material confirmed the presence of PPO only in the seedlings. Catalytic action of the PPO of seedlings was compared to that of the commercial laccase from Trametes versicolor. Sunflower PPO was selectively active on caffeic and chlorogenic acids, less active on ferulic acid and not active on mono-phenols and gallic acid. Conversely, laccase was highly active on all the assessed phenols. PPO activity was good in a large range of pH (4–8), whilst it was approximately halved in solutions containing 35% ethyl alcohol (v/v), 500 mg L⁻¹ citric acid and finally 200 mg L⁻¹ sulphur dioxide. In conclusion, sunflower seedlings can be considered a potential and interesting plant source of PPO. Sunflower PPO could be used to oxidise selectively o-diphenols, for example in alcoholic and nonalcoholic beverages.     

Insights into SO2 Interaction with Pd/Co3O4–CeO2 Catalysts for Methane Oxidation

The catalytic performance and the sulphur resistance of a Pd (0.7 wt%) catalyst supported over Co₃O₄(30 wt%)–CeO₂(70 wt%) mixed oxide were investigated in the oxidation of methane under stoichiometric and lean conditions. The catalytic behaviour was compared with that of two reference catalysts, palladium supported over pure Co₃O₄ and CeO₂. Catalysts were characterized by XRD, BET, XPS and FTIR measurements. Regeneration by a CH₄-reducing treatment at 600 °C was investigated.