Chemistry of a Nitrosyl Ligand ¿:¿-Bridging a Ditungsten Center: rearrangement and N–O Bond cleavage reactions

The novel nitrosyl-bridged complex [W2Cp2(μ-PtBu2)(μ-κ:η-NO)(CO)(NO)](BAr4) [Ar = 3,5-C6H3(CF3)2] was prepared in a multistep procedure starting from the hydride [W2Cp2(μ-H)(μ-PtBu2)(CO)4] and involving the new complexes [W2Cp2(μ-PtBu2)(CO)4](BF4), [W2Cp2(μ-PtBu2)(CO)2(NO)2](BAr4), and [W2(μ-κ:η5-C5H4)Cp(μ-PtBu2)(CO)(NO)2] as intermediates, which follow from reactions with HBF4·OEt2, NO, and Me3NO·2H2O, respectively. The nitrosyl-bridged cation easily added chloride upon reaction with [N(PPh3)2]Cl, with concomitant NO rearrangement into the terminal coordination mode, to give [W2ClCp2(μ-PtBu2)(CO)(NO)2], and underwent N–O and W–W bond cleavages upon the addition of CNtBu to give the mononuclear phosphinoimido complex [WCp(NPtBu2)(CNtBu)2](BAr4). Another N–O bond cleavage was induced upon photochemical decarbonylation at 243 K, which gave the oxo- and phosphinito-bridged nitrido complex [W2Cp2(N)(μ-O)(μ-OPtBu2)(NO)](BAr4), likely resulting from a N–O bond cleavage step following decarbonylation

Solución numérica del problema inverso de Fraunhofer con técnicas de regularización

En este artículo se estudia un modelo matemático concreto proveniente de laconstrucción de un equipo medidor de diámetros de partículas esféricas medianteel empleo de técnicas láser. Se analiza la dificultad del cálculo de su soluciónnumérica y se describen algunas de la.'>técnicas de regularización más recomendadaspara este tipo de problemas. Se muestran los principales resultados deuna extensa experimentación numérica realizada con datos reales, a partir delos cuales se dan conclusiones sobre el mejor método a utilizar

Solución numérica del problema inverso de Fraunhofer con técnicas de regularización

En este artículo se estudia un modelo matemático concreto proveniente de laconstrucción de un equipo medidor de diámetros de partículas esféricas medianteel empleo de técnicas láser. Se analiza la dificultad del cálculo de su soluciónnumérica y se describen algunas de la.'>técnicas de regularización más recomendadaspara este tipo de problemas. Se muestran los principales resultados deuna extensa experimentación numérica realizada con datos reales, a partir delos cuales se dan conclusiones sobre el mejor método a utilizar

Solución numérica del problema inverso de Fraunhofer con técnicas de regularización

En este artículo se estudia un modelo matemático concreto proveniente de laconstrucción de un equipo medidor de diámetros de partículas esféricas medianteel empleo de técnicas láser. Se analiza la dificultad del cálculo de su soluciónnumérica y se describen algunas de la.'>técnicas de regularización más recomendadaspara este tipo de problemas. Se muestran los principales resultados deuna extensa experimentación numérica realizada con datos reales, a partir delos cuales se dan conclusiones sobre el mejor método a utilizar

The marginally stable Bethe lattice spin glass revisited

Bethe lattice spins glasses are supposed to be marginally stable, i.e. their equilibrium probability distribution changes discontinuously when we add an external perturbation. So far the problem of a spin glass on a Bethe lattice has been studied only using an approximation where marginally stability is not present, which is wrong in the spin glass phase. Because of some technical difficulties, attempts at deriving a marginally stable solution have been confined to some perturbative regimes, high connectivity lattices or temperature close to the critical temperature. Using the cavity method, we propose a general non-perturbative approach to the Bethe lattice spin glass problem using approximations that should be hopeful consistent with marginal stability.Comment: 23 pages Revised version, hopefully clearer that the first one: six pages longe

A numerical study of the overlap probability distribution and its sample-to-sample fluctuations in a mean-field model

In this paper we study the fluctuations of the probability distributions of the overlap in mean field spin glasses in the presence of a magnetic field on the De Almeida-Thouless line. We find that there is a large tail in the left part of the distribution that is dominated by the contributions of rare samples. Different techniques are used to examine the data and to stress on different aspects of the contribution of rare samples.Comment: 13 pages, 11 figure

Continuous phase transition in a spin-glass model without time-reversal symmetry

We investigate the phase transition in a strongly disordered short-range three-spin interaction model characterized by the absence of time reversal symmetry in the Hamiltonian. In the mean-field limit the model is well described by the Adam-Gibbs-DiMarzio scenario for the glass transition; however in the short-range case this picture turns out to be modified. The model presents a finite temperature continuous phase transition characterized by a divergent spin-glass susceptibility and a negative specific heat exponent. We expect the nature of the transition in this 3-spin model to be the same as the transition in the Edwards-Anderson model in a magnetic field, with the advantage that the strong crossover effects present in the latter case are absent.Comment: 19 pages, Latex, 16 ps figure

Sustainable strategies based on glycine–betaine analogue ionic liquids for the recovery of monoclonal antibodies from cell culture supernatants

Monoclonal antibodies (mAbs) are of crucial interest for therapeutic purposes, particularly in vaccination and immunization, and in the treatment of life-threatening diseases. However, their downstream processing from the complex cell culture media in which they are produced still requires multiple steps, making mAbs extremely high-cost products. Therefore, the development of cost-effective, sustainable and biocompatible purification strategies for mAbs is in high demand to decrease the associated economic, environmental and health burdens. Herein, novel aqueous biphasic systems (ABS) composed of glycine–betaine analogue ionic liquids (AGB-ILs) and K2HPO4/KH2PO4 at pH 7.0, the respective three-phase partitioning (TPP) systems, and hybrid processes combined with ultrafiltration were investigated and compared in terms of performance as alternative strategies for the purification and recovery of anti-human interleukin-8 (anti-IL-8) mAbs, which are specific therapeutics in the treatment of inflammatory diseases, from Chinese Hamster Ovary (CHO) cell culture supernatants. With the studied ABS, mAbs preferentially partition to the IL-rich phase, with recovery yields up to 100% and purification factors up to 1.6. The best systems were optimized in what concerns the IL concentration, allowing to take advantage of IL-based three-phase partitioning approaches where a precipitate enriched in mAbs is obtained at the ABS interface, yielding 41.0% of IgG with a purification factor of 2.7 (purity of 60.9%). Hybrid processes combining the two previous techniques and an ultrafiltration step were finally applied, allowing the recovery of mAbs from the different fractions in an appropriate buffer solution for further biopharmaceutical formulations, while allowing the simultaneous IL removal and reuse. The best results were obtained with the hybrid process combining TPP and ultrafiltration, allowing to obtain mAbs with a purity higher than 60%. The recyclability of the IL was additionally demonstrated, revealing no losses in the purification and recovery performance of these systems for mAbs. The biological activity of anti-IL-8 mAbs is maintained after the several purification and recovery steps, indicating that the novel ABS, three-phase partitioning and hybrid processes comprising AGB-ILs are promising and sustainable strategies in mAbs downstream processing.publishe