Safe operating conditions for semibatch processes involving consecutive reactions with autocatalytic behavior

When strongly exothermic chemical processes are dealt with, safe and productive operating conditions may be difficult to identify; particularly if the reaction scheme is complex and the desired product is an intermediate. In this work, a new procedure for building boundary and temperature diagrams is developed to account for arbitrary kinetic expressions and multiple reactions. Such a procedure has been validated by comparison with literature experimental data involving autocatalytic consecutive reactions.     

Catalytic olefin epoxidation with cationic molybdenum(VI) cis-dioxo complexes and ionic liquids

The complexes [MoO₂Cl(HC(bim)₃)]Y (Y = Cl (1), BF₄ (2) and PF₆ (3)) have been prepared by reaction of MoO₂Cl₂(THF)₂ (for 1) or [MoO₂Cl(THF)₃]Y (for 2 and 3) with the tridentate ligand HC(bim)₃ = tris(benzimidazolyl)methane, and characterized by IR and Raman spectroscopy, and ¹H NMR. The turnover frequencies for the epoxidation of cis-cyclooctene at 55 °C with tert-butyl hydroperoxide (TBHP, in decane) as the oxidant and complexes 1–3 as catalysts are in the range of 70–200 mol mol_Mo^?1 h^?1. 1,2-Epoxycyclooctane is always the only reaction product for reaction times up to 24 h. With the aim of facilitating the recyclability of the complexes, the ionic liquids (ILs) [BMIM]Y and [BMPy]Y (BMIM = 1-n-butyl-3-methylimidazolium, BMPy = 1-n-butyl-3-methylpyridinium; Y = BF₄ or PF₆) were applied as ionic solvents. The catalytic performance for cyclooctene epoxidation depends strongly on the catalyst solubility in the IL. Of the 12 catalyst/IL mixtures examined, the systems 1/[BMIM]PF₆ and 1/[BMPy]PF₆ exhibit the most favorable reaction rates allied with good recyclability. The 1/[BMIM]PF₆ system was further applied using different oxidants (aqueous TBHP, aqueous H₂O₂ and urea–hydrogen peroxide adduct) and olefins (norbornene, cyclohexene, styrene, α-pinene).     

Erythroid Induction of Chronic Myelogenous Leukemia K562 Cells Following Treatment with a Photoproduct Derived from the UV‐A Irradiation of 5‐Methoxypsoralen

Induction of terminal erythroid differentiation can be an efficient strategy to inhibit proliferation of chronic myelogenous leukemia cells. Psoralens, well‐known photo‐chemotherapeutic agents, were found to be efficient at inducing erythroid differentiation of K562 cells, an in vitro cell line isolated from the pleural effusion of a patient with chronic myelogenous leukemia in blast crisis. The effects of crude pre‐irradiated solutions of 5‐methoxypsoralen on erythroid differentiation of human leukemic K‐562 cells were evaluated. The major photoproduct was characterized and analyzed, and it was found to induce erythroid differentiation of K562 cells and inhibit NF‐κB/DNA interactions.     

Thermodynamics and kinetics of phase transformation in intercalation battery electrodes - phenomenological modeling

Thermodynamics and kinetics of phase transformation in intercalation battery electrodes are investigated by phenomenological models which include a mean-field lattice-gas thermodynamic model and a generalized Poisson-Nernst-Planck equation set based on linear irreversible thermodynamics. The application of modeling to a porous intercalation electrode leads to a hierarchical equivalent circuit with elements of explicit physical meanings. The equivalent circuit corresponding to the intercalation particle of planar, cylindrical and spherical symmetry is reduced to a diffusion equation with concentration dependent diffusivity. The numerical analysis of the diffusion equation suggests the front propagation behavior during phase transformation. The present treatment is also compared with the conventional moving boundary and phase field approaches.     

Polyamide 6 nanofibrous nonwovens via electrospinning

Electrospinning of Polyamide 6 (PA 6) in 2,2,2‐trifluoroethanol (TFE) was investigated for the fabrication of nanofibrous nonwoven membranes useful for separation systems. The effects of solution characteristics such as concentration and conductivity as well as the effects of processing conditions such as relative humidity and applied potential on the resultant nonwoven fibers were studied. By changing the relative humidity of the electrospinning chamber and the conductivity of the solvent, it is possible to modulate the fiber's size and consequently the porosity of the mats. The morphology of the electrospun PA 6 nanofibers was observed by scanning electron microscopy. The mechanical properties of the nanofibers were also studied. The results showed that PA 6 nanofibers having a diameter ranging from 100 to 600 nm, has been successfully prepared. The electrospun PA 6 nanofiber mats show good mechanical properties, such as a high‐tensile strength (12 ± 0.2 MPa) and elongation (300% ± 50%). The strength of the web was high enough to use as filter without the need of any supporting matrix and could be applicable in the field of self‐supporting membranes. The X‐ray and DSC analyses of the PA 6 electrospun fibers show the presence of the γ‐form of PA 6 crystallite that is usually obtained in the condition where a high stress of the fibers is applied. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Hot stamping of AA5083 aluminium alloy sheets

The paper is aimed at proving the feasibility of producing sheet components by stamping AA5083 sheets at elevated temperature and strain rate. Laboratory tensile and Nakajima-type tests were carried out to evaluate the material flow stress, ductility and fracture limits sensitivity to temperature and strain rate, and therefore to determine the optimal combination of process parameters assuring both maximum formability and effective post-deformation mechanical properties. Industrial trials were conducted on an automotive component to validate the laboratory results.     

Risk Factors for Retinal Ganglion Cell Distress in Glaucoma and Neuroprotective Potential Intervention

Retinal ganglion cells (RGCs) are a population of neurons of the central nervous system (CNS) extending with their soma to the inner retina and with their axons to the optic nerve. Glaucoma represents a group of neurodegenerative diseases where the slow progressive death of RGCs results in a permanent loss of vision. To date, although Intra Ocular Pressure (IOP) is considered the main therapeutic target, the precise mechanisms by which RGCs die in glaucoma have not yet been clarified. In fact, Primary Open Angle Glaucoma (POAG), which is the most common glaucoma form, also occurs without elevated IOP. This present review provides a summary of some pathological conditions, i.e., axonal transport blockade, glutamate excitotoxicity and changes in pro-inflammatory cytokines along the RGC projection, all involved in the glaucoma cascade. Moreover, neuro-protective therapeutic approaches, which aim to improve RGC degeneration, have also been taken into consideration.     

A Novel Genetic Variant in the WFS1 Gene in a Patient with Partial Uniparental Mero-Isodisomy of Chromosome 4

Wolfram syndrome is a rare autosomal recessive disorder characterized by optic atrophy and diabetes mellitus. Wolfram syndrome type 1 (WFS1) is caused by bi-allelic pathogenic variations in the wolframin gene. We described the first case of WFS1 due to a maternal inherited mutation with uniparental mero-isodisomy of chromosome 4. Diabetes mellitus was diagnosed at 11 years of age, with negative anti-beta cells antibodies. Blood glucose control was optimal with low insulin requirement. No pathogenic variations in the most frequent gene causative of maturity-onset diabetes of the young subtypes were detected. At 17.8 years old, a rapid reduction in visual acuity occurred. Genetic testing revealed the novel homozygous variant c.1369A>G; p.Arg457Gly in the exon 8 of wolframin gene. It was detected in a heterozygous state only in the mother while the father showed a wild type sequence. In silico disease causing predictions performed by Polyphen2 classified it as “likely damaging”, while Mutation Tester and Sift suggested it was “polymorphism” and “tolerated”, respectively. High resolution SNP-array analysis was suggestive of segmental uniparental disomy on chromosome 4. In conclusion, to the best of our knowledge, we describe the first patient with partial uniparental mero-isodisomy of chromosome 4 carrying a novel mutation in the wolframin gene. The clinical phenotype observed in the patient and the analysis performed suggest that the genetic variant detected is pathogenetic.     

Mutual Information in Molecular and Macromolecular Systems

The relaxation properties of viscous liquids close to their glass transition (GT) have been widely characterised by the statistical tool of time correlation functions. However, the strong influence of ubiquitous non-linearities calls for new, alternative tools of analysis. In this respect, information theory-based observables and, more specifically, mutual information (MI) are gaining increasing interest. Here, we report on novel, deeper insight provided by MI-based analysis of molecular dynamics simulations of molecular and macromolecular glass-formers on two distinct aspects of transport and relaxation close to GT, namely dynamical heterogeneity (DH) and secondary Johari–Goldstein (JG) relaxation processes. In a model molecular liquid with significant DH, MI reveals two populations of particles organised in clusters having either filamentous or compact globular structures that exhibit different mobility and relaxation properties. In a model polymer melt, MI provides clearer evidence of JG secondary relaxation and sharper insight into its DH. It is found that both DH and MI between the orientation and the displacement of the bonds reach (local) maxima at the time scales of the primary and JG secondary relaxation. This suggests that, in (macro)molecular systems, the mechanistic explanation of both DH and relaxation must involve rotation/translation coupling.