Functional mesoporous poly(ionic liquid)-based copolymer monoliths: From synthesis to catalysis and microporous carbon production

Ionic liquid-functionalized mesoporous polymeric networks with specific surface area up to 935 m²/g have been successfully synthesized one pot by solvothermal copolymerization of divinylbenzene and monomeric ionic liquids. The as-obtained polymers exhibit a monolithic structure featuring large pore volumes, an abundant mesoporosity and an adjustable content of ionic liquids. The effect of the reaction conditions on the pore structure has been studied in detail. These poly(ionic liquid)-based porous networks (PILPNs) have then been employed as precursors in two distinct applications, namely organocatalysis and production of microporous carbon monoliths. Selected organocatalyzed reactions, including carbonatation of propylene oxide by cycloaddition with carbon dioxide, benzoin condensation, and cyanosilylation of benzaldehyde have been readily triggered by PILPNs acting as crosslinked polymer-supported (pre)catalysts. The two latter reactions required the prior deprotonation of the imidazolium salt units with a strong base to successfully generate polymer-supported N-heterocyclic carbenes, referred to as poly(NHC)s. Facile recycling and reuse of polymer-supported (pre)catalysts was achieved by simple filtration owing to the heterogeneous reaction conditions. Furthermore, PILPNs could be easily converted into microporous carbon monoliths via CO₂ activation.     

Dietary krill oil increases docosahexaenoic acid and reduces 2-arachidonoylglycerol but not N-acylethanolamine levels in the brain of obese Zucker rats

Evidence suggests that dietary long chain polyunsaturated fatty acids (LCPUFAs), and particularly those belonging to the n-3 family, may influence the brain fatty acid profile and, thereby, the biosynthesis of endocannabinoids in rodents. However, the doses used are usually quite high and not comparable with human intake. Recently, we have shown that relatively low doses of dietary n-3 LCPUFAs (4 weeks), in the form of either fish or krill oil, balanced for EPA and DHA content, and against a control diet with no EPA and DHA and similar contents of oleic, linoleic and α-linolenic acids, lower the concentrations of the endocannabinoids, anandamide (AEA) and 2-arachidonoylglycerol (2-AG), in the visceral adipose tissue, and of AEA in the liver and heart, of obese Zucker rats. This, in turn, is associated with lower levels of arachidonic acid in membrane phospholipids and with amelioration of some metabolic syndrome parameters. We investigated here whether in Zucker rats, under the same conditions, fish and krill oil are also able to influence LCPUFA and endocannabinoid profiles in brain. Only krill oil was able to increase significantly DHA levels in brain phospholipids, with no changes in arachidonic acid. DHA increase was associated with lower levels of 2-AG in the brain, whereas AEA and its congeners, N-palmitoylethanolamine and N-oleoylethanolamine, were unchanged. We conclude that, despite the strong impact of dietary n-3 fatty acid on endocannabinoid levels previously observed in peripheral tissues, in the brain only 2-AG is affected by dietary krill oil, suggesting that the beneficial effect of the latter on the metabolic syndrome is mostly exerted by modifying peripheral endocannabinoids. Nevertheless, possible effects of dietary krill oil in the brain through modification of 2-AG levels deserve further investigation.     

Simulating the Response of Composite Plates to Fire

The present paper introduces a numerical study on the fire behavior of composites during exposure to a heating source at high incident power. A novel numerical model is proposed which is able to simulate the behavior of composite materials in fire environment providing the composites mass loss rate and heat release rate during heating source application. Two commercial software have been selected as platforms for the implementation of the proposed numerical model COMSOL and ANSYS. In COMSOL the model has been implemented by introducing proper field equations, while a macro, written in Ansys Parametric Design Language, has been used to allow the ANSYS FEM code to numerically simulate, by an incremental procedure, all the relevant physical phenomena related to fire. As an application, an experiment on thermal degradation over a laminated composite plate has been numerically simulated and the numerical model has been validated by comparing the COMSOL and Ansys numerical results to experimental literature data in terms of temperature profile over the panel thickness, Mass Loss Rate and Heat Release Rate. An excellent agreement has been found between the obtained numerical results and the experimental test data for both the adopted numerical platforms. However the ANSYS implementation, which showed to be the most effective in terms of accuracy of results and perspectives of applications to complex numerical models, led to the definition of a powerful tool able to assesses the fire performance of composite structures.     

Effects of boundary conditions on testing of pipes and finite element modelling

The design of many submarine pipelines, especially for operating in deep water, relies on accurate test results for the local buckling collapse of pipes subjected to bending loading. Recent test results have shown apparently anomalous values of axial tensile and compressive strains in comparison to the values that would be expected on the basis of simple bending theory. This could have important consequences for the efficacy of the design factors derived using these anomalous results. Examples of anomalous test results are given in the paper and the cause of the differences between the strain values obtained in the tests and those expected on the basis of simple bending theory are explained using finite element modelling.The major point is that the general application of the simplified engineering theory of bending can be erroneous when ovalisation is imposed or, on the contrary, the boundary conditions of the section are restrained from ovalising deformations.This is a crucial limit state for the design of onshore and offshore pipelines.     

Integration of acoustical information in the perception of impacted sound sources: The role of information accuracy and exploitability.

Sound sources are perceived by integrating information from multiple acoustical features. The factors influencing the integration of information are largely unknown. We measured how the perceptual weighting of different features varies with the accuracy of information and with a listener’s ability to exploit it. Participants judged the hardness of two objects whose interaction generates an impact sound: a hammer and a sounding object. In a first discrimination experiment, trained listeners focused on the most accurate information, although with greater difficulty when perceiving the hammer. We inferred a limited exploitability for the most accurate hammer-hardness information. In a second rating experiment, listeners focused on the most accurate information only when estimating sounding-object hardness. In a third rating experiment, we synthesized sounds by independently manipulating source properties that covaried in Experiments 1 and 2: sounding-object hardness and impact properties. Sounding-object hardness perception relied on the most accurate acoustical information, whereas impact-properties influenced more strongly hammer hardness perception. Overall, perceptual weight increased with the accuracy of acoustical information, although information that was not easily exploited was perceptually secondary, even if accurate. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Flicker noise measurement of HF quartz resonators

Frequency flicker of quartz resonators can be derived from the measurement of S(phi) (f), i.e., the power spectrum density of phase fluctuations phi. The interferometric method appears to be the best choice to measure the phase fluctuations of the quartz resonators because of its high sensitivity in the low power conditions, which is required for this type of resonator. Combining these two ideas, we built an instrument suitable to measure the frequency flicker floor of the quartz resonators, and we measured the stability of some 10-MHB high performance resonators as a function of the dissipated power. The stability limit of our instrument, described in terms of Allan deviation sigma(y)(tau), is of some 10(-14).     

Lupus anticoagulant, anticardiolipin antibodies and hepatitis C virus infection in thalassaemia

Anticardiolipin antibodies (ACA) and lupus anticoagulant (LA) have been detected in patients with hepatitis C virus (HCV) infection and have been associated in autoimmune diseases (i.e. systemic lupus erythematosus) with an increased risk of thromboembolic events. Because of the high prevalence of HCV infection and the thrombotic risk described in thalassaemia we decided to investigate the prevalence of ACA and LA in a cohort of 68 thalassaemia patients. We found a high prevalence (34%) of beta2-glycoprotein I independent ACA in our thalassaemia patients which was related to HCV infection. None of patients developed any complications related to antiphospholipid antibodies (APL); therefore the clinical significance of positivity for APL in patients with HCV infection is at present unclear. In conclusion, the results of our study indicate that ACA in the serum of HCV-infected thalassaemic patients exhibit the characteristics of natural autoantibodies rather than those of the pathogenic autoantibodies that are found in patients with systemic lupus erythematosus.     

An acoustic-emission characterization of the failure modes in polymer-composite materials

A new methodology for the analysis of failure modes in composite materials by means of acoustic emission techniques has been developed. A single-carbon-fiber composite based on a polyester matrix, has been used as a simple model. The occurrence of fiber-breakage during tensile loading tests has been observed by a polarized light microscope and concurrently detected by a resonant acoustic probe. The resonant probe has been used as a trigger for the reading of fiber failure events. Single acoustic emission events from a wide-band probe has been recorded for FFT Analysis. The single-fiber specimen, having a unique failure mode, has advantages for the standardization of AE techniques for the quantitative analysis of failures in polymer-composite materials.

The same procedure can be exploited to investigate other failure modes namely, fiber matrix solidus debonding and matrix cracking.     

A LOGICAL CHARACTERIZATION FOR TRUTH MAINTENANCE SYSTEMS WITH DEPENDENCY-DIRECTED BACKTRACKING

In this paper we present various logical characterizations of justification-based (nonmonotonic) truth maintenance systems (JTMS). These characterizations, which are proved to be equivalent, aim at describing dependency-directed backtracking (DDB) (i.e., the process of resolving conflicts which can arise when nogoods are allowed in the set of justifications), mainly relying on the intuitive idea that a contrapositrve use of justifications is needed to resolve inconsistencies. The idea is first formalized by means of the notion of three-valued labeling and then through a transformation which explicitly adds all contrapositives of the justifications. An abductive characterization of the JTMS is provided through a further transformation which converts a set of nonmonotonic justifications to a corresponding abduction framework. This approach provides a unifying framework, based on the notion of abduction, for describing both JTMSs and assumption-based TMSs (ATMSs).