Influence of ion mobility on the redox and catalytic properties of Cu ions in zeolites

This contribution aims at analysing the current understanding about the influence of Al distribution, zeolite topology, ligands/reagents and oxidation state on ions mobility in Cu-zeolites, and its relevance toward reactivity of the metal sites. The concept of Cu mobilization has been originally observed in the presence of ammonia, favouring the activation of oxygen by formation of NH₃ oxo-bridged complexes in zeolites and opening a new perspective about the chemistry in single-site zeolite-based catalysts, in particular in the context of the NH₃-mediated Selective Catalytic Reduction of NO_x (NH₃-SCR) processes. A different mobility of bare Cu⁺/Cu²⁺ ions has been documented too, showing for Cu⁺ a better mobilization than for Cu²⁺ also in absence of ligands. These concepts can have important consequences for the formation of Cu-oxo species, active and selective in other relevant reactions, such as the direct conversion of methane to methanol. Here, assessing the structure, the formation pathways and reactivity of Cu-oxo mono- or multimeric moieties still represents a challenging playground for chemical scientists. Translating the knowledge about Cu ions mobility and redox properties acquired in the context of NH₃-SCR reaction into the field of direct conversion of methane to methanol can have important implications for a better understanding of transition metal ions redox properties in zeolites and for an improved design of catalysts and catalytic processes.

The mobility of Cu ions in zeolites is influenced by oxidation state, ligands, zeolite topology and chemical composition. The known and possible implications for catalytic activity of Cu-zeolites are discussed.     

2‐[(1‐Imidazolyl)formyloxy]ethyl methacrylate as a new chemical precursor of functional polymers

A novel activated derivative of methacrylic acid, namely 2‐[(1‐imidazolyl)formyloxy]ethyl methacrylate was synthesized and homopolymerized. The resulting polymer was used in exchange reactions with alcohols and amines, thus showing a potential for the synthesis of multifunctional polymers. All reactions, expecially those carried out in the presence of amines, proceeded under mild conditions. 2‐[(1‐Imidazolyl)formyloxy]ethyl methacrylate can also be regarded as a valuable precursor for the preparation of new and easily polymerizable functional monomers.     

Complexity theory and collaboration: An agent-based simulator for a space mission design team

In this paper, we investigate how complexity theory can benefit collaboration by applying an agent-based computer simulation approach to a new form of synchronous real-time collaborative engineering design. Fieldwork was conducted with a space mission design team during their actual design sessions, to collect data on their group conversations, team interdependencies, and error monitoring and recovery practices. Based on the fieldwork analysis, an agent-based simulator was constructed. The simulation shows how error recovery and monitoring is affected by the number of small group, or sidebar, conversations, and consequent noise in the room environment. This simulation shows that it is possible to create a virtual environment with cooperating agents interacting in a dynamic environment. This simulation approach is useful for identifying the best scenarios and eliminating potential catastrophic combinations of parameters and values, where error recovery and workload in collaborative engineering design could be significantly impacted. This approach is also useful for defining strategies for integrating solutions into organizations. Narjès Bellamine-Ben Saoud is an Associate Professor at the University of Tunis and Researcher at RIADI-GDL Laboratory, Tunisia. After Computer Science engineering diploma (1993) of the ENSEEIHT of Toulouse, France, she received her PhD (1996), on groupware design applied to the study of cooperation within a space project, from the University of Toulouse I, France. Her main research interests concern studying complex systems particularly by modeling and simulating collaborative and socio-technical systems; developing Computer Supported Collaborative Learning in tunisian primary schools; and Software Engineering. Her current reserach projects include modeling and simulation of emergency rescue activities for large-scale accidents, modeling of epidemics and study of malaria, simulation of collabration artifacts. Gloria Mark is an Associate Professor in the Department of Informatics, University of California, Irvine. Dr. Mark received her Ph.D. in Psychology from Columbia University in 1991. Prior to UCI, she was a Research Scientist at the GMD, in Bonn, Germany, a visiting research scientist at the Boeing Company, and a research scientist at the Electronic Data Systems Center for Advanced Research. Dr. Mark’s research focuses on the design and evaluation of collaborative systems. Her current projects include studying worklife in the network-centric organization, multi-tasking of information workers, nomad workers, and a work in a large-scale medical collaboratory. Dr. Mark is widely published in the fields of CSCW and HCI, is currently the program co-chair for the ACM CSCW’06 conference and is on the editorial board of Computer Supported Cooperative Work: The Journal of Collaborative Computing, and e-Service Qu@rterly.     

THE RELATIVE EFFICIENCY OF DIFFERENT STANDARDS WHEN FIRMS VARY

Pollution standards in practice take many forms, such as measuring pollution per unit of output rather than just restricting pollution. This paper uses simulations to provide some evidence on the effects of these two forms of standards when firms vary. For the cases studied, it shows that a pollution standard can lead to higher profits, but a pollution-per-output standard leads to higher output and lower price; the overall efficiency effects are therefore ambiguous.     

Surface green function matching approach to the surface dynamics of ionic crystals: I. Equivalence with the invariant green function method

The surface Green function matching (SGFM) method is shown to be equivalent to the Green function method in its translationally and rotationally invariant formulation (IGF). Such equivalence between matching and invariance conditions makes the SGFM method easily applicable to the surface dynamics of ionic crystals, due to the existing possibility of deriving an effective short-range perturbation from the invariance conditions. An application to the inelastic scattering of He from LiF(001) in the eikonal approximation is presented.     

Quaternionic Starters

Let m be an integer, m 2 and set n = 2^m. Let G be a non-cyclic group of order 2n admitting a cyclic subgroup of order n. We prove that G always admits a starter and so there exists a one–factorization of K_2n admitting G as an automorphism group acting sharply transitively on vertices. For an arbitrary even n > 2 we also show the existence of a starter in the dicyclic group of order 2n.Research performed within the activity of INdAM–GNSAGA with the financial support of the Italian Ministry MIUR, project Strutture Geometriche, Combinatoria e loro Applicazioni     

Linear and non-linear optical properties of 2,5-disubstituted pyrroles supported by a catalyst-free SiO2 sonogel network

The preparation and optical characterization of pyrrole based sol-gel hybrid materials generated by ultrasonic irradiation (Sonogel composites) are presented in this work. Pyrrole compounds were recently synthesized in our group by a modification of the Schulte-Reisch reaction; these molecular systems were dissolved at different concentrations in tetrahydrofuran (THF) and optimally embedded into a catalyst-free SiO₂ sonogel network. For this purpose, we exploited the novel catalyst-free (CF) sonolysis route to produce highly pure sol-gel glasses, generated via sonochemical reactions. This approach has been recently developed in our research group and has been successfully implemented to develop several hybrid composites for optical applications. By this method, homogeneous and stable solid-state hybrid samples suitable for optical characterization can be produced. The high porosity exhibited by the sonogel matrix allowed us to prepare several pyrrole doped composites with variable dopant concentration. The linear and nonlinear optical (NLO) properties of these amorphous hybrid structures were determined by absorption- and photoluminescent (PL)-spectroscopies, and by the optical third harmonic generation (THG) techniques, respectively. The implemented catalyst-free sonolysis route produced SiO₂-host networks of high chemical and optical purity, suitable for optical and photonic applications.     

Direct-type vinylogous Mukaiyama-Michael addition reactions involving pyrrolinone donors

The direct Mukaiyama-Michael addition of vinylogous tetramate donors to a number of different Michael acceptors has been easily executed, by employing the TMSOTf/Et₃N mixture as soft Lewis acid/base promoter agent. Richly functionalized, highly manipulable γ-substituted pyrrolinone products were practically synthesized in acceptable to excellent yields, and with diastereoselectivities heavily relying upon the substituent at the nitrogen atom of the pyrrolinone donor.