Synthesis and characterization of water-soluble poly(p-phenylene vinylene) derivatives via the dithiocarbamate precursor route

Two hydrophilic branched oligo(ethylene glycol)-substituted PPV derivatives, poly(2,5-bis(1,3-bis(triethoxymethoxy)propan-2-yloxy)-1,4-phenylene vinylene) (BTEMP-PPV) and poly(2-methoxy-5-(1,3-bis(triethoxymethoxy)propan-2-yloxy)-1,4-phenylene vinylene) (MTEMP-PPV), are presented. Polymerizations have been performed via the dithiocarbamate precursor route, using lithium hexamethyldisilazide (LHMDS) as a base, to obtain high molecular weight precursor polymers. After thermal conversion of the precursor polymers into the fully conjugated systems, the solubility of the polymers has been examined. The polar nonionic side chains of MTEMP-PPV and BTEMP-PPV render the PPV backbone soluble in a variety of solvents, including alcohols and even water, making these polymers suitable candidates to be used in optoelectronic devices that can be processed from environmentally friendly solvent systems.     

Quasi-analytic solutions of linear parabolic equations

Uniqueness of solutions of the Cauchy problem of a parabolic equation, and the related question of analyticity with respect to time, depend on global properties of the solution. We demonstrate that if the growth of the initial function (and, if relevant, of the inhomogeneous part and its derivatives) is not too great, solutions of non-stationary parabolic equations whose coefficients belong to quasi-analytic classes are quasi-analytic with respect to all variables and hence are unique. This study is motivated by the problem of endogenous completeness in continuous-time financial markets.     

Involvement of miR-190b in Xbp1 mRNA Splicing upon Tocotrienol Treatment

We previously demonstrated that apoptosis induced by tocotrienols (γ and δT3) in HeLa cells is preceded by Ca²⁺ release from the endoplasmic reticulum. This event is eventually followed by the induction of specific calcium-dependent signals, leading to the expression and activation of the gene encoding for the IRE1α protein and, in turn, to the alternative splicing of the pro-apoptotic protein sXbp1 and other molecules involved in the unfolded protein response, the core pathway coping with EndoR stress. Here, we showed that treatment with T3s induces the expression of a specific set of miRNAs in HeLa cells. Data interrogation based on the intersection of this set of miRNAs with a set of genes previously differentially expressed after γT3 treatment provided a few miRNA candidates to be the effectors of EndoR-stress-induced apoptosis. To identify the best candidate to act as the effector of the Xbp1-mediated apoptotic response to γT3, we performed in silico analysis based on the evaluation of the highest ∆ in Gibbs energy of different mRNA–miRNA–Argonaute (AGO) protein complexes. The involvement of the best candidate identified in silico, miR-190b, in Xbp1 splicing was confirmed in vitro using T3-treated cells pre-incubated with the specific miRNA inhibitor, providing a preliminary indication of its role as an effector of EndoR-stress-induced apoptosis.     

Full backward non-homogeneous semi-Markov processes for disability insurance models: A Catalunya real data application

In this paper a stochastic model for disability insurance contracts is presented. The model is based on a discrete time non-homogeneous semi-Markov process to which the backward recurrence time process is joined. This permits us to study in a more complete way the disability evolution and to face the duration problem in a more effective way. The model is applied to a sample of contracts drawn at random from a mutual insurance company.     

Effective balance equations for elastic composites subject to inhomogeneous potentials

We derive the new effective governing equations for linear elastic composites subject to a body force that admits a Helmholtz decomposition into inhomogeneous scalar and vector potentials. We assume that the microscale, representing the distance between the inclusions (or fibers) in the composite, and its size (the macroscale) are well separated. We decouple spatial variations and assume microscale periodicity of every field. Microscale variations of the potentials induce a locally unbounded body force. The problem is homogenizable, as the results, obtained via the asymptotic homogenization technique, read as a well-defined linear elastic model for composites subject to a regular effective body force. The latter comprises both macroscale variations of the potentials, and nonstandard contributions which are to be computed solving a well-posed elastic cell problem which is solely driven by microscale variations of the potentials. We compare our approach with an existing model for locally unbounded forces and provide a simplified formulation of the model which serves as a starting point for its numerical implementation. Our formulation is relevant to the study of active composites, such as electrosensitive and magnetosensitive elastomers.     

Heterogeneous enantioselective epoxidation of olefins catalysed by unsymmetrical (salen)Mn(III) complexes supported on amorphous or MCM-41 silica through a new triazine-based linker

High enantioselectivity (ee up to 84%) has been achieved in heterogeneous asymmetric epoxidation using a silica-bound unsymmetrical (salen)-manganese(III) complex; amorphous silica can be used in the same way as MCM-41, showing a positive effect in the catalyst recycling.     

Instationary conjugate optical-thermal fields in thin films due to pulsed laser heating: A comparison between back and front treatment

Manufacturing of multilayer thin films deposited on a glass substrate can be accomplished by means of pulsed laser sources. Thermal and optical nonlinearities are induced during transient heating, since the response of weakly absorbing thin films depends on the temperature. The heat source can either directly impinge the film surface,␣front treatment, or the glass substrate, back treatment. In this paper a one-dimensional conjugate non-linear thermal-optical time dependent problem is numerically analysed. The investigation is accomplished in order to compare the two processes. For a Nd-YAG laser with wavelength of 1064 nm, a a-Si/TCO and Al/a-Si/TCO multilayers are investigated. Results are presented in form of spatial and temporal temperature profiles as well as absorbed heat transfer rates inside the layers. The accomplished analysis clearly shows that the back treatment is more efficient in terms of manufacturing process, oriented to the production of photovoltaic cells. Received on 4 November 1997