Ti location in the MFI framework of Ti-Silicalite-1: a neutron powder diffraction study.

The first direct evidence that Ti atoms are not equally distributed in the 12 crystallographically independent T sites of the MFI framework is presented on the basis of neutron diffraction data collected at the HRPD instrument of the ISIS pulsed neutron source. We found strong evidence indicating that T6, T7, and T11 are the most populated sites and weak evidence that Ti may be hosted in T10. Ti occupancy can be excluded for sites T1, T2, T4, T5, T9, and T12. The occupancy of the remaining sites is doubtful. Since defective silicalite has been shown to exhibit the same preferential sites (T6, T7, T11, and T10) for Si vacancies, it may be suggested that the incorporation mechanism of the Ti atoms in the MFI framework occurs via the insertion of titanium in the defective sites. This hypothesis implies that titanium has a mineralizing effect on the MFI framework, and it is supported by independent spectroscopic data on both TS-1 and defective silicalite. The results are discussed in comparison with the known substitution mechanisms in the T-sites of MFI-type structures.     

Ring‐opening polymerization of cyclic esters promoted by phosphido‐diphosphine pincer group 3 complexes

Phosphido‐diphosphine Group 3 metal complexes 1–4 [(o‐C₆H₄PR₂)₂P‐M(CH₂SiMe₃)₂; R = Ph, 1 : M = Y, 2 : M = Sc; R = iPr, 3 : M = Y, 4 : M = Sc] are very efficient catalysts for the ring‐opening polymerization (ROP) of cyclic esters such as ε‐caprolactone (ε‐CL), L ‐lactide, and δ‐valerolactone under mild polymerization conditions. In the ROP of ε‐CL, complexes 1–4 promote quantitative conversion of high amount of monomer (up to 3000 equiv) with very high turnover frequencies (TOF) (～4 × 10⁴ mol_CL/mol_I h) showing a catalytic activity among the highest reported in the literature. The immortal and living ROP of ε‐CL and L ‐lactide is feasible by combining complexes 1–4 with 5 equiv of 2‐propanol. Polymers with controlled molecular parameters (M_n, end groups) and low polydispersities (M_w/M_n = 1.05–1.09) are formed as a result of fast alkoxide/alcohol exchange. In the ROP of δ‐valerolactone, complexes 1–4 showed the same activity observed for lactide (L ‐ and D ,L ‐lactide) producing high molecular weight polymers with narrow distribution of molar masses. Complexes 1–4 also promote the ROP of rac‐β butyrolactone affording atactic low molecular weight poly(hydroxybutyrate) bearing unsaturated end groups probably generated by elimination reactions. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

A simplified flood routing model: variable prameter muskingum (VPM)

Summary Flood routing methods are numerical methods for estimating the movement of a flood wave along a channel reach, on the basis of the knowledge of the discharge hydrograph at the upstream end and of the hydraulic characteristics of the reach and, usually, in the hypothesis that no perturbation is coming from downstream (free boundary condition). The flood routing method wich is proposed is similar to the Muskingum one, but with variable and hydraulic parameters; it is able to estimate water levels too; is effective even if kinetic terms are not completely negligible; take advantage of the insignificance of the downstream condition and make it possible to obtain results starting upstream and proceeding downstream; for simplicity's sake, take advantage of the fact that the discharge loop of normal flood waves is quite small. Obtained results are much better that those obtainable from constant parameters methods and indeed, if the flood loop is less that 10%, very similar to those obtainable from more complex and time consuming models.

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Sommario I metodi di flood routing studiano la propagazione di un'onda di piena lungo un tratto di un corso d'acqua, assegnato l'andamento temporale della portata nella sezione di monte e le caratteristiche dell'alveo, e usualmente nell'ipotesi di assenza di perturbazioni provenienti da valle (condizione di valle passiva). Viene qui proposto un procedimento di flood routing, formalmente simile ad un Muskingum ma con i parametri variabili e calcolati per via idraulica; idoneo a stimare anche i livelli idrici; valido anche se i termini cinetici non sono del tutto trascurabili; che sfrutta l'irrilevanza della condizione di valle procedendo a cascata da monte a valle; che sfrutta, a vantaggio della semplicità, il fatto che per le normali onde di piena dei corsi d'acqua il cappio di portata è di dimensioni modeste. I risultati ottenuti sono molto migliori di quelli ottenibili con metodi a parametri costanti e, almeno per i casi in cui il cappio relativo è inferiore al 10%, paragonabili a quelli ottenuti con metodi molto più complessi ed onerosi.

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List of symbols x, t channel distance, starting upstream; time - z water surface height above datum - Q volumetric rate of discharge - P(x, z) steady rating curve - q=Q–P flood loop - g acceleration of gravity - A, B cross section wetted area and free surface width - I, S water surface slope and friction slope - c kinematic wave velocity - F Froude number - L,L ₀,L ₁,L ₂,L ₃ characteristic lengths of the channel - T=L/c characteristic time of the channel - D diffusion - p, l time and space steps - K, X Muskingum parameters - C ₁,C ₂,C ₃,C ₄ Muskingum coefficients - f _x=f/x,f _t=f/t etc. for the partial derivatives Paper presented at the First Italian Meeting of Computational Mechanics held in Milan, June 24–26, 1986.     

Synthesis of derivatives of pyrazolo[1,5-a]pyrrolo[1,2-c][1,3,6]-benzotriazocine,a new class of compounds with potential CNS activity

The synthesis of derivatives of pyrazolo[1,5-a]pyrrolo[1,2-c][1,3,6]benzotriazocine was obtained by the reaction of arylaldehydes with some 1-(2-aminophenyl)-5-(pyrrol-1-yl)pyrazoles, as hydrochlorides. Characterization of this new class of compounds was effected with ir, pmr and ¹³C nmr spectral data.     

二元样条的并行算法（英）

In this paper, we propose an algorithm for the reduction of a real sparse matrix that arises from the construction of certain spline surfaces to ‘block diagonal’ form. The approach is to aggregate matrix elements in similar position and to apply them in a blocked fashion, thus splitting the initial linear system into independent and parallelizable linear subsystems. The results suggest that it is possible to use a large number of processors to solve the above matrix problem at a relatively fine granularity.     

The Pathmox approach for PLS path modeling: Discovering which constructs differentiate segments

The problem of heterogeneity represents a very important issue in the decision‐making process. Furthermore, it has become common practice in the context of marketing research to assume that different population parameters are possible depending on sociodemographic and psycho‐demographic variables such as age, gender, and social status. In recent decades, numerous approaches have been proposed with the aim of involving heterogeneity in the parameter estimation procedures. In partial least squares path modeling, the common practice consists of achieving a global measurement of the differences arising from heterogeneity. This leaves the analyst with the important task of detecting, a posteriori, which are the causal relationships (ie, path coefficients) that produce changes in the model. This is the case in Pathmox analysis, which solves the heterogeneity problem by building a binary tree to detect those segments of population that cause the heterogeneity. In this article, we propose extending the same Pathmox methodology to asses which particular endogenous equation of the structural model and which path coefficients are responsible of the difference.     

Reactivity of Ti(IV) species hosted in TS-1 towards H2O2-H2O solutions investigated by ab initio cluster and periodic approaches combined with experimental XANES and EXAFS data: a review and new highlights

This work is intended to underline how the most-advanced experimental and theoretical physical chemistry tools must be used synergistically to understand the reactivity of Ti-silicalite-1 (TS-1) in an important number of low-temperature oxidation reactions with aqueous H(2)O(2) as the oxidant. Literature results are carefully reviewed and accompanied with new, unpublished highlights of both experimental and computational origin. The first part of this work is devoted to a discussion of the defective nature of the material and to the synergic role played by Si vacancies and Ti insertion in the framework. A summary of the experimental Ti-K-edge EXAFS and XANES literature concerning the activated material in vacuo conditions is then presented and compared to the corresponding Ti geometries obtained by ab initio calculations. From such a comparison, the excellent agreement between experiment and theory is evident. A very good agreement is also obtained for the interaction with water and ammonia. For both H(2)O and NH(3), the agreement is due to the possibility to perform experiments in which the probe molecule is dosed from the gas phase, thus allowing to reach the 1 : 1 (or 1 : 2) ratio between the adsorbing Ti sites and the adsorbed molecule. Then, interaction with hydrogen peroxide is discussed, underlining the problems faced in reaching a common view between experimental and theoretical results, owing to the difficulties both in performing experiments where anhydrous H(2)O(2) is dosed on TS-1, and in taking into account the role played by the aqueous medium in the reactivity of Ti(iv) centres toward H(2)O(2) using ab initio calculations. Only once such difficulties have been overcome, by increasing the complexities of both experiments and ab initio models, is a joint-view finally obtained. Where needed, comparison with other experimental results (X-ray and neutron diffraction, NMR, IR, Raman, UV-vis and resonant Raman) is made.     

Optimization of photodynamic therapy response by survivin gene knockdown in human metastatic breast cancer T47D cells

Photodynamic therapy (PDT) leads to the generation of cytotoxic oxygen species that appears to stimulate several different signaling pathways, some of which lead to cell death, whereas others mediate cell survival. In this context, we observed that PDT mediated by methyl-5-aminolevulinic acid as the photosensitizer resulted in over-expression of survivin, a member of the inhibitor of apoptosis (IAP) family that correlates inversely with patient prognosis. The role of survivin in resistance to anti-cancer therapies has become an area of intensive investigation. In this study, we demonstrate a specific role for survivin in modulating PDT-mediated apoptotic response. In our experimental system, we use a DNA vector-based siRNA, which targets exon-1 of the human survivin mRNA (pSil_1) to silence survivin expression. Metastatic T47D cells treated with both pSil_1 and PDT exhibited increased apoptotic indexes and cytotoxicity when compared to single-agent treated cells. The treatment resulted in increased PARP and caspase-3 cleavage, a decrease in the Bcl-2/Bak ratio and no participation of heat shock proteins. In contrast, the overexpression of survivin by a survivin-expressed vector increased cell viability and reduced cell death in breast cancer cells treated with PDT. Therefore, our data suggest that combining PDT with a survivin inhibitor may attribute to a more favorable clinical outcome than the use of single-modality PDT.     

Exact Riemann Solution and Weighted Average Flux Method for Power-law Channel Section

The aim of this work is to extend the Weighted Averaged Flux (WAF) method by E.F. Toro from rectangular to generic regular cross sections, in order to represent the geometric effects of the cross-section on wave propagation along channels. Assuming a power-law variation of the channel width, the 1D conservative shallow water equations, their characteristic form and the shock propagation equations are presented. The exact Riemann solver is derived and is applied to the dam-break problem in valleys with different shape in order to test its efficiency and to check the accuracy order of solutions obtained by approximating the real cross-section with an equivalent rectangle. The WAF method is extended to a power-law channel section and is used to solve the 1D proposed equations taking into account all the source terms that are incorporated into the local Riemann problem. A code based on this method has been developed and results of numerical applications to a Venturi channel and to the attenuation of waves are presented, in order to verify, for well known situations, how accurately the source terms are represented. The code is applied to reproduce one of Brock's experiments (1969; 1970) on roll waves generation in a rectangular channel and results are compared with those obtained with a Godunov-type code developed at CEMAGREF, which is based on a Roe scheme with a later average evaluation of source terms.