Pre- and post-scission light charged particle multiplicities in incomplete fusion reactions

In this article we present results concerning the extraction of light charged particle multiplicities in incomplete fusion-fission reactions with a moving source fitting procedure. To demonstrate the feasibility and reliability of the procedure we have used simulated events of known multiplicity to construct kinetic energy distributions at different angles that are fitted assuming several pre- and post-scission sources. In particular, we show that it is necessary to include at least two pre-equilibrium sources in order to extract correctly the known pre-equilibrium proton multiplicity. These two sources are characterized by high ernission temperatures, low emission barriers and high velocities, having ~ 70% and ~ 25% of the beam velocity along the beam axis, respectively The former source is naturally dominant at forward angles due to the strong focusing effect of its high velocity, Contrary to normal expectations, however, the slower pre-equilibrium source is present with considerable yield at the most backward angles θ ~ 145° where it is normally assumed only evaporative components are present. The estracted proton multiplicities are well reproduced by the moving source procedure, as well as fitting parameters with physical relevance

MECHANISTIC STUDY OF A RUTHENIUM HYDRIDE COMPLEX OF TYPE [RuH(CO)(N-N)(PR3)2]+ AS CATALYST PRECURSOR FOR THE HYDROFORMYLATION REACTION OF 1-HEXENE

Indexación: Web of Science; Scopus; Scielo.The catalytic activity of systems of type [RuH(CO)(N-N)(PR3)(2)](+) was evaluated in the hydroformylation reaction of 1-hexene. The observed activity is explained through a reaction mechanism on the basis of the quantum theory. The mechanism included total energy calculations for each of the intermediaries of the elemental steps considered in the catalytic cycle. The deactivation of the catalyst precursors takes place via dissociation of the polypyridine ligand and the subsequent formation of thermodynamically stable species, such as RuH(CO)(3)(PPh3)(2) and RuH3(CO)(PPh3)(2), which interrupt the catalytic cycle. In addition, the theoretical study allows to explain the observed regioselectivity which is defined in two steps: (a) the hydride migration reaction with an anti-Markovnikov orientation to produce the alkyl-linear-complex (3.1a), which is more stable by 19.4 kJ/mol than the Markovnikov orientation (alkyl-branched-complex) (3.1b); (b) the carbon monoxide insertion step generates the carbonyl alkyl-linear specie (4.1a) which is more stable by 9.5 kJ/mol than the alternative species (4.1b), determining the preferred formation of heptanal in the hydroformylation of 1-hexene. Palabras clavehttp://ref.scielo.org/db4yc

\u27The World is Too Messy\u27: The Challenge of Historical Literacy in a General-Education Course

The problem with implementing writing-intensive (or writing-emphasis) liberal arts general education (GE) courses is as evident as it is underacknowledged; that is, this seemingly well-bounded, modest reform involves significant change-on multiple levels and for multiple players in complex institutional and disciplinary activity systems. We know a little about such issues: Writing-across-the-curriculum (WAC) programs are often said to present new challenges for teachers, such as a felt tension between the demands of teaching writing and covering content, and the need for substantial background in writing pedagogy (Russell, Writing in the Academic Disciplines). Although such tensions are both urgent and real, they do not reflect the depth and range of changes a movement to discipline-based writing can entail-in terms of institutional traditions, departmental modes of operation, classroom practice, and students\u27 understandings. And it is crucial to remember that liberal arts courses are almost always in some discipline. Michael Fullan\u27s work on educational change suggests that although these processes may appear technically simple, they are in fact socially complex (The New Meaning 5), invoking individual and collective feelings of loss, anxiety, and struggle (The New Meaning 31; Fullan Change Forces). When attempting change, cautions Fullan, a good rule of thumb is to assume that changing the culture of institutions is the real agenda, not implementing single innovations (The New Meaning 107)

Correlation Effects in Side-Coupled Quantum Dots

Using Wilson's numerical renormalization group (NRG) technique we compute zero-bias conductance and various correlation functions of a double quantum dot (DQD) system. We present different regimes within a phase diagram of the DQD system. By introducing a negative Hubbard U on one of the quantum dots, we simulate the effect of electron-phonon coupling and explore the properties of the coexisting spin and charge Kondo state. In a triple quantum dot (TQD) system a multi-stage Kondo effect appears where localized moments on quantum dots are screened successively at exponentially distinct Kondo temperatures.Comment: 13 pages, 10 figure