Preparation of highly dispersed CuO catalysts on oxide supports for de-NO(x) reactions

CuO based catalysts dispersed on silica-alumina supports at low (0.56 wt.%) and high (13 wt.%) Al(2)O(3) content were prepared by adsorption method with or without ultrasound treatment. The catalysts obtained were studied in their bulk (atomic absorption, X-ray diffraction, temperature programmed reduction) and surface (N(2) adsorption and X-ray photoelectron spectroscopy) properties. Significant differences between the series of catalysts prepared over the two supports in terms of size of the CuO aggregates and of their redox properties were evidenced. All the catalysts were tested in the selective catalytic reduction of NO(x) using C(2)H(4) as reducing species (HC-SCR process) in highly oxidant atmosphere. The CuO-catalysts prepared using ultrasounds were the most active. Moreover, they displayed a peculiar activity being able to activate NO both by reducing it to N(2), in larger extent, and by oxidizing it to NO(2).     

Vitellin cleavage products are proteolytically degraded by ubiquitination in stick insect embryos

Vitellin polypeptides are proteolytically processed in ovarian follicles and embryos of the stick insect Carausius morosus. Data show that vitellin polypeptide A(3) of 54kDa is processed to yield polypeptide A(3)(*) of about 48kDa upon completion of ovarian development, whereas vitellin polypeptide A(2) of 90kDa yields polypeptide E(9) during embryonic development. As vitellin polypeptides are processed, polypeptides A(3)(*) and E(9) are transferred from the yolk granules to the cytosolic space of the vitellophages and start to express a ubiquitin reactivity. At the confocal microscope, anti-ubiquitin antibodies label specifically numerous small yolk granules and the cytosolic space of vitellophages. During embryonic development, ubiquitin carrying granules undergo acidification in much the same way as larger yolk granules. However, only these latter organelles are capable of converting a latent cysteine pro-protease into an active yolk protease upon acidification of their luminal space. These data are interpreted as indicating that ubiquitin-like polypeptides are restricted to small granules throughout ovarian and embryonic development, and that vitellin cleavage products are ubiquitinated following acidification of large yolk granules and transfer to the cytosolic space of the vitellophages.     

Nonlinear Elliptic Differential Equations with Multivalued Nonlinearities

In this paper we study nonlinear elliptic boundary value problems with monotone and nonmonotone multivalued nonlinearities. First we consider the case of monotone nonlinearities. In the first result we assume that the multivalued nonlinearity is de_ned on all . Assuming the existence of an upper and of a lower solution, we prove the existence of a solution between them. Also for a special version of the problem, we prove the existence of extremal solutions in the order interval formed by the upper and lower solutions. Then we drop the requirement that the monotone nonlinearity is defined on all of . This case is important because it covers variational inequalities. Using the theory of operators of monotone type we show that the problem has a solution. Finally, in the last part we consider an eigenvalue problem with a nonmonotone multivalued nonlinearity. Using the critical point theory for nonsmooth locally Lipschitz functionals we prove the existence of at least two nontrivial solutions (multiplicity theorem).     

Thermal and structural analysis and crystallization behavior of new poly(ether-alkyl) oxadiazoles

A new series of poly(ether-alkyl)oxadiazoles of general formula: with m = 3, 4, and 5 has been obtained from the corresponding polyhydrazides through thermal cyclization reaction. The polymers were characterized by infrared spectroscopy, differential scanning calorimetry, wide-angle x-ray analysis, and optical microscopy. The polymers were crystalline, with a crystalline texture and structural parameters strongly dependent on the value of m. The T_m's and T_g's value decreased with increasing number of CH₂. © 1994 John Wiley & Sons, Inc.     

Structural study of alkaloids from securidaca longipedunculata roots. II. Isolation and characterization by supercritical fluid chromatography/mass spectrometry

Various alkaloids obtained from the methanol extracts of the roots of Securidaca Longipedunculata Fres. were studied using supercritical fluid chromatography/mass spectrometry. This hyphenated method and parallel unimolecular and collisionally activated decomposition experiments on electron impact-generated molecular ions gave information on the structure of compounds. The presence of the ergoline skeleton in some of them was assigned.     

On the connectedness of the first cohomology module for rank two vector bundles on projective space

We provide sufficient conditions for the connectedness of the Hartshorne-Rao module of integral subcanonical curves and of the first cohomology module for rank two vector bundles on projective space.

---

Sunto Si danno condizioni sufficienti per la connessità del modulo di Hartshorne-Rao di una curva integra sottocanonica e del primo modulo di coomologia di un fibrato vettoriale di rango due sullo spazio proiettivo.

     

Transverse effects in collective atomic recoil lasing

We investigate transverse effects in collective atomic recoil lasing (CARL), where a cold atomic sample is lightened by a far detuned laser beam resonant with the internal atomic transition. The gradient force of the scattered radiation field produces a collective self-focusing on the atoms, which could be observed in a Bose-Einstein condensate stored in a bidirectional optical ring cavity or in the superradiant CARL-BEC regime.     

A kinetic study of the conjugate addition of benzenethiol to cyclic enones catalyzed by a nonsymmetrical uranyl-salophen complex

The Et3N-assisted addition of benzenethiol to enones in chloroform is catalyzed with high turnover efficiency by the phenyl-substituted uranyl-salophen compound 3. Catalytic data show a close adherence to a quatermolecular mechanism involving reaction of a base-activated thiol with a reversibly formed complex of enone and metal catalyst, with a complication of product inhibition due to the formation of a product-catalyst complex. The role of the binding energy made available by interactions with the aromatic sidearm of the catalyst is discussed in terms of catalyst-substrate and catalyst-transition state complementarity.     

Solid-phase synthesis of N-nosyl- and N-Fmoc-N-methyl-alpha-amino acids

We report here a convenient and simple solid-phase synthesis of N-nosyl-N-methyl-alpha-amino acids and N-Fmoc-N-methyl-alpha-amino acids, important building blocks for the synthesis of conformationally restricted and protease-resistant natural peptides and peptide analogues. The methodology involves the use of 2-chlorotrityl chloride resin to temporarily protect the carboxylic group of alpha-amino acids and of diazomethane as the reagent to methylate the sulfonamidic function. The approach developed is particularly efficient also with alpha-amino acids bearing appropriately protected functionalized side chains.