A new characterisation of hereditary pi rings

In this paper we prove a new characterisation of hereditary PI rings, namely we show that a Noetherian, but not Artinian, PI ringR that is an order in an Artinian ring splits into a direct sum of an Artinian ring of finite representation type and hereditary semiprime rings if and only if all its proper Artinian factor rings are of finite representation type. We also show, through examples, that the above characterisation does not hold for some more general settings. Supported by the EC via TMR-Fellowship ERB4001GT63713.     

Sol-Gel Nanosized Semiconducting Titania-Based Powders for Thick-Film Gas Sensors

Pure, 5 at%, and 10 at% Ta- or Nb-doped TiO₂ nanosized powders were prepared by the sol-gel method. The powders heated to 400°C have the crystalline anatase structure. While the pure TiO₂ powder heated to 850°C has the rutile structure, the addition of Ta and Nb inhibited the anatase-to-rutile phase transformation at this temperature. Ta was soluble in the titania lattice up to the concentration of 10 at%, while the solubility of Nb was 5 at%. Thick films were fabricated with these powders by screen printing technology and then fired at 650°C and 850°C for 1 h. SEM observations showed that the anatase-to-rutile phase transformation induces a grain growth of about one order of magnitude for pure TiO₂. The addition of Ta and Nb is effective to keep the TiO₂ grain size at the nanometric level even at 850°C. Conductance measurements showed that a good gas response is observed only for the nanostructured titania-based films. The CO response of these materials is only slightly affected by humidity.     

Gaussian Limiting Behavior of the Rescaled Solution to the Linear Korteweg–de Vries Equation with Random Initial Conditions

We analyze the asymptotic behavior of the rescaled solution to the linear Korteweg–de Vries equation when the initial conditions are supposed to be random and weakly dependent. By means of the method of moments we prove the Gaussianity of the limiting process and we present its correlation function. The same technique is applied to the analysis of another third-order heat-type equation.     

Application of the anionic homologous Fries‐rearrangement to the synthesis of 3‐alkylbenzofuran‐2(3H)‐ones

We have developed an effective organometallic‐based procedure allowing the employment of 2‐methylphenols as easily available starting materials in the synthesis of 3‐alkylbenzofuran‐2(3H)‐ones. The first step of this protocol, an anionic homologous Fries‐rearrangement, afforded 2‐(2‐ tert ‐butyldimethylsilyloxyaryl)acetamides, which were selectively metalated and monoalkylated at the benzylic position. Acidic work‐up of crude products afforded the desired heterocycles in satisfactory overall yields. Copyright © 2008 John Wiley & Sons, Ltd.     

Entanglement as a Semantic Resource

The characteristic holistic features of the quantum theoretic formalism and the intriguing notion of entanglement can be applied to a field that is far from microphysics: logical semantics. Quantum computational logics are new forms of quantum logic that have been suggested by the theory of quantum logical gates in quantum computation. In the standard semantics of these logics, sentences denote quantum information quantities: systems of qubits (quregisters) or, more generally, mixtures of quregisters (qumixes), while logical connectives are interpreted as special quantum logical gates (which have a characteristic reversible and dynamic behavior). In this framework, states of knowledge may be entangled, in such a way that our information about the whole determines our information about the parts; and the procedure cannot be, generally, inverted. In spite of its appealing properties, the standard version of the quantum computational semantics is strongly “Hilbert-space dependent”. This certainly represents a shortcoming for all applications, where real and complex numbers do not generally play any significant role (as happens, for instance, in the case of natural and of artistic languages). We propose an abstract version of quantum computational semantics, where abstract qumixes, quregisters and registers are identified with some special objects (not necessarily living in a Hilbert space), while gates are reversible functions that transform qumixes into qumixes. In this framework, one can give an abstract definition of the notions of superposition and of entangled pieces of information, quite independently of any numerical values. We investigate three different forms of abstract holistic quantum computational logic.     

Commensurability classification of a family of right-angled Coxeter groups

We classify the members of an infinite family of right-angled Coxeter groups up to abstract commensurability.

     

Study of the reaction Fe(CN)4(bpy)2− + S2O82− in Sulfobetaine Aqueous Micellar Solutions

The reaction Fe(CN)₄(bpy)^2? + S₂O₈^2? has been studied in aqueous micellar solutions of N‐tetradecyl‐N,N‐dimethyl‐3‐ammonio‐1‐propanesulfonate, SB3‐14. The influence of changes in the surfactant concentration as well as in the peroxodisulfate ions concentration on k_obs was investigated. Spectroscopic and conductivity measurements have given information about the distribution of both anionic reagents between the aqueous and micellar pseudophases of the SB3‐14 micellar solutions. A discussion about the adequacy of various equations based on the pseudophase model to rationalize kinetic micellar effects for anion‐anion reactions in sulfobetaine micellar solutions has been done. © 2001 John Wiley & Sons, Inc. Int J Chem Kinet 33: 225–231, 2001     

An eco-friendly tandem tosylation/Ferrier N-glycosylation of amines catalyzed by Er(OTf)3 in 2-MeTHF

Er(OTf)₃ in 2-MeTHF provides a new and eco-friendly process for Ferrier glycosylation of sulfonamides and amino acids with various N-nucleophiles.The stereoselective synthesis of 2,3-unsaturated-N-pseudoglycals was carried out with 3,4,6-tri-O-acetyl-d-glucal and different nucleophiles affording good results in a short time.     

Determination of Antioxidant Activity of Hibiscus Flowers by Flow Injection Analysis with Chemiluminescence Detection

This study reports a simple and rapid method for the determination of the antioxidant activity of the phenolics present in plants of the Hibiscus genus. The protocol is based on the ability of the phenolic compounds to inhibit luminol chemiluminescence through the inactivation of free radicals in a flow injection system. Using the optimized operational conditions, the antioxidant activities of several phenolics were measured. The results were explained on the basis of structure–reactivity relationships. The antioxidant activities of dried flowers of Hibiscus rosa-sinensis and Hibiscus sabdariffa were evaluated. The protocol was validated by the 2,2-diphenyl-1-picrylhydrazyl-hydrate free radical assay. The differences in the antiradical activities were explained based on the concentrations of total polyphenol and flavonoid concentrations determined by spectrophotometric methods. It was concluded that the chemiluminescence method was complementary for the evaluation of hydrophilic antioxidants in plants.     

Sensitive Determination of the Diquat Herbicide in Fresh Food Samples on a Highly Boron‐Doped Diamond Electrode

The highly boron‐doped diamond electrode (HBDD) combined with square wave voltammetry (SWV) was used in the development of an analytical procedure for diquat determination in potato and sugar cane samples and lemon, orange, tangerine and pineapple juices. Preliminary experiments realised in a medium of 0.05 mol L^?1 Na₂B₄O₇ showed the presence of two voltammetric peaks around ?0.6 V and around ?1.0 V vs. Ag/AgCl/Cl^? 3.0 mol L^?1, where the first peak could be successfully used for analytical proposes due the facility in the electrode surface renovation. After the experimental and voltammetric optimisation, the calculated detection and quantification limits were 1.6×10^?10 mol L^?1 and 5.3×10^?10 mol L^?1 (0.057 µg L^?1 and 0.192 µg L^?1, respectively), which are lower than the maximum residue limit established for fresh food samples by the Brazilian Sanitary Vigilance Agency. The proposed methodology was used to determine diquat residues in potato and sugar cane samples and lemon, orange, tangerine and pineapple juices and the calculated recovery efficiencies indicated that the proposed procedure presents higher robustness, stability and sensitivity, good reproducibility, and is very adequate for diquat determination in complex samples.