k-intolerant capacities and Choquet integrals

We define an aggregation function to be (at most) k-intolerant if it is bounded from above by its kth lowest input value. Applying this definition to the discrete Choquet integral and its underlying capacity, we introduce the concept of k-intolerant capacities which, when varying k from 1 to n, cover all the possible capacities on n objects. Just as the concepts of k-additive capacities and p-symmetric capacities have been previously introduced essentially to overcome the problem of computational complexity of capacities, k-intolerant capacities are proposed here for the same purpose but also for dealing with intolerant or tolerant behaviors of aggregation. We also introduce axiomatically indices to appraise the extent to which a given capacity is k-intolerant and we apply them on a particular recruiting problem.     

Synthesis and characterization of polyethylene film grafted with acrylic acid and diethyleneglycol-dimethacrylate

Acrylic acid (AA) and diethyleneglycol-dimethacrylate (DEGDM) are grafted onto 25 μm low-density radio-peroxided polyethylene. Monomer content is determined by exchange capacity measurements. Studies of electrical resistance and zero-current membrane potential allow for the determination of the influence of DEGDM on both the dissociation of grafted AA and the permselectivity of these so-obtained cation-exchange membranes. DEGDM, acting as a crosslinking agent, limits the AA degree of grafting, slightly increases the electrical resistance, but contributes to enhance the permselectivity. For example, when these grafted films are immersed in 3M NaCl aqueous solutions, the addition of DEGDM leads to an increase of the transport number of Na⁺ close to 20%. © 1993 John Wiley & Sons, Inc.     

A propos de la structure de pyrimidines obtenues par condensation de l'acide cyanacétique et de monoalkylurées

Classically, the condensation of cyanoacetic acid and monoalkylurea gives 1-alkyl-6-amino-1,2,3,4-tetrahydropyrimidine-2,4-dione. However, this was verified only in two instances involving a long and delicate synthesis. The structure of the N′-cyanoacetyl-N-isobutylurea, an intermediate in the preparation of this type of pyrimidine, was confirmed by nmr. This method is capable of extension.     

Corniculoside,a New Biosidic Ester Secoiridoid from Halenia corniculata

Chemical screening of the secondary metabolites from Halenia corniculata L. (CORNAZ ), by LC/UV,LC/TSP-MS (thermospray), and LC/ES-MS (electrospray) was used for the targeted isolation of corniculoside ( 1 ), a new biosidic ester secoiridoid. The structure was established as 7-β-[(E)-4′-O-(β-D -glucopyranosyl)caffeoyloxy]-sweroside by 1D- and 2D-NMR, LC/UV, LC/MS, and FAB-MS data, in combination with chemical reactions.     

Über enolisierte Derivate der Chlorophyllreihe. 132-Desmethoxycarbonyl-173-desoxy-132,173-cyclochlorophyllid a-enol und eine Methode zur Einführung von Magnesium in porphinoide Ligandsysteme unter milden Bedingungen. (Vorläufige Mitteilung)

Enol derivatives in the chlorophyll series. 13²-Desmethoxycarbonyl-17³-desoxy-13²,17³-cyclochlorophyllide a-enol and a method for the introduction of magnesium into porphinoid ligands under mild conditions Magnesium transfer from the iodo-magnesium salt of 3,5-di-t-butyl-4-hydroxy-toluene (BHT) into methyl pheophorbide a is a fast process in methylenechloride/ether solution at ambient temperature. This procedure for the introduction of magnesium into labile chlorin ligands has made possible the preparation of a crystalline 13², 17³-cyclochlorophyllide a-enol. Concomitant use of the lithium salt of BHT facilitates the more critical insertion of magnesium into methyl bacteriopheophorbide a. The preparative success of these magnesium transfers depends crucially upon the solvent system used. Under conditions where the complexation of methyl pheophorbide a with iodo-magnesium-BHT is essentially complete within 2 minutes at 12° in methylenechloride/ether solution, strong inhibition of the magnesium transfer is observed by cosolvents such as pyridine, dimethylacetamide, dioxan or tetrahydrofuran.     

Effective conjugation and Raman intensities in oligo(para-phenylene)s: a microscopic view from first-principles calculations

Electron-phonon coupling in oligo(para-phenylene)s is addressed in terms of the off-resonance Raman intensities of two distinct modes at 1220 and 1280 cm(-1). On the basis of Albrecht's theory, vibrational coupling and Raman intensities are calculated from first-principles quantum-chemical methods. A few-state model is used to evaluate the dependence of the mode intensities on oligomer length, planarity, and excitation wavelength. The link between electron delocalizationconjugation and Raman intensities is highlighted. Extending on prior studies, the present work focuses on providing an in-depth understanding of the origin of this correlation in addition to reproducing experimental findings. The model applied here allows us to interpret the results on a microscopic, quantum-mechanical basis and to relate the observed trends to the molecular orbital structure and nature of the excited states in this class of materials. We find quantitative agreement between the results of the calculations and those of measurements performed on oligo(para-phenylene)s of various chain lengths in the solid state and in solution.     

N- and P-channel transport behavior in thin film transistors based on tricyanovinyl-capped oligothiophenes

We report the structural and electrical characterization of thin films of organic semiconductor molecules consisting of an oligothiophene core capped with electron-withdrawing tricyanovinyl (TCV) groups. X-ray diffraction and atomic force microscopy of evaporated films of three different TCV-capped oligothiophenes showed that the films were highly crystalline. Electrical transport was measured in thin film transistors employing silver source and drain contacts and channel probes to correct for contact resistance. Three compounds exhibited n-channel (electron) conduction consistent with cyclic voltametry data that indicated they undergo facile reduction. Maximum electron mobilities were 0.02 cm2/V.s with an on/off current ratio of 10(6). A fourth end-capped molecule, TCV-6T-TCV, which had six thiophene rings, exhibited both p- and n-channel transport. Overall, these results confirm that substitution of oligothiophene cores with electron-withdrawing groups is a useful strategy to achieve electron-transporting materials.