LC/ESI-MS/MS characterisation of procyanidins and propelargonidins responsible for the strong antioxidant activity of the edible halophyte Mesembryanthemum edule L.

Mesembryanthemum edule is used as a food ingredient and in traditional medicine. In this study, we investigated antioxidant activities of several extracts (methanol/acidified water, v/v: 20/80; 40/60 and 60/40) obtained from M. edule leaf, stem and root. Then, individual phenolics were characterised by reverse-phase HPLC coupled to electrospray ionisation mass spectrometry and multi-stage MS fragment analysis. Results showed that 40% methanol leaf extract, 40% methanol root extract and 20% methanol stem extract displayed the highest scavenging activity against DPPH and ABTS radicals. Regarding LC/ESI-MS/MS identification of active phenols, there were significant differences among the fractions of interest. In fact, 40% leaf extract mainly contained procyanidins, whereas propelargonidins were the major phenolics in 20% methanol stem extract, while, in 40% root extract, the active compounds remained unidentified. These results indicate that edible M. edule can be used as a nutraceutical in the pharmaceutical industry.     

A critical approach to viscosity index

The viscosity index (VI) is a useful tool for lubricant users and refiners, since it is a measure of the effect of temperature changes on the viscosity of the oil. However, it was found that the viscosity index does not correlate with the flow activation energy E_a, which is the theoretically defined dependence of the viscosity on temperature. In this way, two oils may have the same flow activation energy but a viscosity index varying by up to 120. We therefore believe that the VI does not always give a proper representation of the effect of temperature on the kinematic viscosity.¹³C NMR spectroscopy was used to identify the molecules with a high VI. Twenty different oil samples produced from eight different vacuum gas oils with viscosity indices ranging from −104 to 146 were analyzed and key parameters identified for high VI molecules: long alkyl chains, methyl branching in the centre of the molecule, low content of aromatic compounds, no ethyl branching and no tertiary carbons.A correlation based on four selected peaks was developed, giving a very good prediction of the viscosity index.     

Symmetric delay factorization: generalized framework forparaunitary filter banks

The symmetric delay factorization (SDF) was introduced to synthesize linear-phase paraunitary filter banks (LPPUFBs) with uniform order (i.e., filter length equal to NM for arbitrary N) and real-valued coefficients. The SDF presents the advantage of decomposing the polyphase transfer matrix (PTM) into only orthogonal matrices, even at the boundary of finite-duration signals, simplifying significantly the design of time-bounded filter banks (TBFBs) or of time-varying filter banks (TVFBs). However, the symmetric delay factorization applies only to LPPUFBs. On the other hand, lattice structures, as well as finite-size lattice structures, are proposed for classes of nonlinear-phase paraunitary filter banks, as the modulated lapped transform (MLT) and the extended tapped transform (ELT). This paper describes a new minimal and complete symmetric delay factorization valid for a larger class of paraunitary filter banks, encompassing paraunitary cosine modulated filter banks, with nonlinear phase basis functions, as well as for a set of LPPUFBs including the linear-phase lapped orthogonal transforms (LOTs) and the generalized tapped orthogonal transforms (GenLOTs). The derivations for filter banks with even and odd numbers of channels are formulated in a unified form. This approach opens new perspectives in the design of time-varying filter banks used for image and video compression, especially in the framework of region or object-based coding     

Influence of morphologic texture on stress analysis by X-ray and neutron diffraction in single-phase metallic materials

In this work, a study on the influence of morphologic texture on the residual stress determination by diffraction in metallic materials with cubic and hexagonal symmetry is proposed. To this end, elastic self-consistent model has been developed to properly take into account the morphologic texture. Extreme crystallites morphologies (sphere, disc and fibre) were studied, and coupled with the crystallographic texture to reflect the combined effect of morphologic and crystallographic texture in elasticity. In the case of morphologic texture, a stronger influence than the crystallographic texture on the estimated residual stresses (several tens of MPa difference) was observed. We propose a methodology through a scale transition model to take into account the influence of these different morphologies in the stress analysis by diffraction methods. The main purpose of this work was to make the best choice for lattice planes (hkl) used for residual or internal stress analysis, in elasticity, depending on the morphologic (and crystallographic) texture of the polycrystal, especially when the usual X-ray Elasticity Constants (XECs) are used instead of the stress factors.     

A Decade of Oxothiomolybdenum Wheels: Synthesis,Behavior in Solution,and Electrocatalytic Properties

The last decade has see the development of sulfur-containing polyoxometalates (POTMs) as a subclass of the polyoxometalate family. The structural and physico-chemical properties of this emerging class of compounds is dominating by the striking coordination properties of the [Mo₂O₂S₂(OH₂)₆]²⁺ oxothio cation, used as a building block. The cyclic topology of this arrangement corresponds to the main feature of the {Mo₂O₂S₂}-based compounds, able to develop cycle-based chemistry. The control of the linear oligomerization of the {Mo₂O₂S₂} core is achieved by the presence of the anionic component, which acts as a template. Here, we report on recent examples which illustrate how the use of various template ions such as halide, sulfate, polyphosphate, and polycarboxylate anions allows to tune the nuclearity of the inorganic host from {Mo₈} to {Mo₁₈}. A special focus on behavior in solution is given, highlighting the dynamic and fluxional character of these host–guest systems. The Diffusion Ordered Spectroscopy (DOSY) ¹H NMR, carried out on a large series of cycle-based and capsule-like compounds, demonstrates that such a method can be applied for the speciation of POM anions in solution. Finally, electrocatalytic behavior of the {Mo₂O₂S₂}-based compounds is presented. Preliminary results show that the electrocatalytic reduction of protons into hydrogen (HER) could constitute one of the most relevant applications for this class of molecular compounds.     

Architectural Control of Freeze-Cast Ceramics Through Additives and Templating

The freezing of concentrated colloidal suspensions is a complex physical process involving a large number of parameters. These parameters provide unique tools to manipulate the architecture of freeze-cast materials at multiple length scales in a single processing step. However, we are still far from developing predictive models to describe the growth of ice crystals in concentrated particle slurries. In order to exert reliable control over the microstructural formation of freeze-cast materials, it is necessary to reach a deeper understanding of the basic relationships between the experimental conditions and the microstructure of the growing solid. In this work, we explore the role of several processing variables (e.g., composition of the suspension, freezing rate, and patterning of the freezing surface) that could affect the formulation strategies for the architectural manipulation of freeze-cast materials. We also demonstrate, using freeze-cast lamellar structures, that reducing the lamellar thickness by less than half increases the compressive strength by more than one order of magnitude.     

Wet air oxidation in a catalytic membrane reactor: Model and industrial wastewaters in single tubes and multichannel contactors

Recent results on catalytic wet air oxidation applied to a membrane contactor are presented that give new insight following a series of previous publications. Model and industrial effluents are treated in both single tube and multichannel catalytic systems. Characterisation of the catalytic material (solid analyses, electron microscopy, EDS and EPMA) is carried out, in order to determine the catalyst distribution. Catalytic results show performances heavily dependent on the nature of the effluent and the operating conditions, and to a lesser extent on the catalytic membrane characteristics. At 80 °C, an industrial effluent is oxidised at a membrane surface related rate of 3.8 mmol/s/m². This result is achieved using a membrane containing about 0.1 wt.% Pt. This allows a revised and improved technico-economical evaluation of the Watercatox process.     

Asymptotic Properties of Monotonic Nonexpansive Mappings

Let T be a nonexpansive monotonic mapping from C to itself where C is a closed subset of a space of bounded real functions, with the supremum norm. We study asymptotic properties of several average iterates of T, related to the cycle time.     

Prevalence and comparison of genetic profiles of Campylobacter strains isolated from poultry and sporadic cases of campylobacteriosis in humans.

Between July 1998 and June 1999, 93 lots of broiler chickens distributed on 57 farms were sampled in two abattoirs of the province of Quebec (Canada). A total of 2,325 samples of cecal material were analyzed to determine the prevalence of campylobacters. Biotyping and pulsed-field gel electrophoresis (PFGE) were done on 20% of the Campylobacter isolates to study the distribution within poultry production. Macrorestriction profiles were compared with profiles of 24 Campylobacter strains isolated from sporadic cases of human diarrheic patients in order to evaluate genetic relationships. Approximately 40% of the broiler chickens in 60% of the lots and 67% of the farms were colonized. Biotypes I and II of Campylobacter jejuni were the most prevalent biotypes in poultry and human isolates. The PFGE dendograms revealed a high genetic diversity among poultry isolates, with 49 different genotypes from the 56 positive lots. More than 75% of these lots were colonized by a unique genotype. All positive lots raised simultaneously on the same farm had common genotype(s). Different genotypes were isolated from lots raised at different grow-out periods on a farm. In some cases, identical genotypes were found at different grow-out periods on a farm and also from different farms. Macrorestriction profiles showed that approximately 20% of human Campylobacter isolates were genetically related to genotypes found in poultry. This genetic relationship and the high prevalence of C. jejuni biotypes I and II in poultry indicated that Campylobacter in broiler production of the province of Quebec could be a potential source of hazard for public health.     

Strategies for combining decision procedures

Implementing efficient algorithms for combining decision procedures has been a challenge and their correctness precarious. In this paper we describe an inference system that has the classical Nelson–Oppen procedure at its core and includes several optimizations: variable abstraction with sharing, canonization of terms at the theory level, and Shostak's streamlined generation of new equalities for theories with solvers. The transitions of our system are fine-grained enough to model most of the mechanisms currently used in designing combination procedures. In particular, with a simple language of regular expressions we are able to describe several combination algorithms as strategies for our inference system, from the basic Nelson–Oppen to the very highly optimized one recently given by Shankar and Rueß. Presenting the basic system at a high level of generality and non-determinism allows transparent correctness proofs that can be extended in a modular fashion when new features are introduced in the system.