Nanoporous networks derived from functional semi-Interpenetrating Polymer Networks: Preparation and use as ion-exchange chromatographic supports

The utilization of poly(ε-caprolactone) (PCL)/poly(methyl methacrylate-co-methacrylic acid)-based semi-Interpenetrating Polymer Networks as nanostructured precursors provides a straightforward and effective route for engineering COOH-functionalized nanoporous networks. Such functional frameworks can be used as cation-exchange supports in Ion-Exchange Chromatography for the separation of proteins, provided the structures contain a significant initial content of carboxylic acid functions. This investigation illustrates the major role played by the presence of the interconnected pores generated by the oligoester template in the protein retention. The resolution turns out to be better than that obtained with a classically prepared porous support using an organic solvent as a porogen.     

Green projects: An information drives analysis of four cases

An analysis of four transportation systems (Vélib, Zipcar, ERP Singapore, and Transantiago) shows the strategic value of creating a symbiotic relationship between physical and informational systems in order to increase the convenience and patronage of these systems. The four information drives (ubiquity, uniqueness, unison, and universality) are extended to a physical setting and used to report the key characteristics of each system from both a physical and informational perspective. The article argues that the traditional customer orientation to determining systems requirements may fail to create the breakthrough systems designs that are required to reduce society’s climate harming emissions. Rather, we need an innovation orientation based on understanding consumers’ fundamental physical and informational needs.     

Intercalated carbon nanotubes as a template for the preparation of supported heteroatomic nanoparticles

Chemistry in confined conditions is explored at the level of the interlayer space of multiwall carbon nanotubes. Starting from preliminary intercalated tubes, a ligand exchange reaction has been successfully conducted within the former Van der Waals gap, resulting in a final dispersion of heteroatomic particles, around 2 nm large and nearly homogeneous in size, on the outer surface of the tubes. Intercalated tubular carbon architectures thus prove to be interesting templates for a bottom-up preparation of chemically complex supported nanoparticles, with potential activities for versatile applications.     

Determination of Electron Collision Cross Sections Set for Tetramethysilane

A swarm analysis technique based on the solution of the Boltzmann equation is used to derive low energy electron collision cross sections for tetramethylsilane （TMS）. The calculated swarm parameters with this first available cross sections set is consistent with measured values of the swarm parameters. Calculations of transport parameters in mixtures of TMS with argon are also presented.     

Rheological properties of injection molded LDPE and mPE foams

The rheological properties of molten LDPE and mPE foams have been measured for small‐amplitude oscillatory shear flow. The foam samples were prepared by injection molding, and the effect of injection conditions on the resultant cell structure is discussed. In all cases cellular foams with closed cells were obtained with cell densities in the range of 4 × 10⁵ ? 7 × 10⁶ cells/cm³ and cell diameters in the range of 30–110 μm. The viscoelastic behavior of the foams is shown to be well described by the emulsion model proposed by Palierne (1) without using any fitting parameter. The linear viscoelastic properties of LDPE and mPE foams depend only on the properties of the polymer matrix and of the gas volume fraction. The Palierne model is also used to predict the linear properties of microcellular foams. Polym. Eng. Sci. 44:2158–2164, 2004. © 2004 Society of Plastics Engineers.     

Aggregation of random parameters Ornstein-Uhlenbeck or AR processes: some convergence results

Abstract.  It is shown that by aggregating simple random parameters, processes such as autoregressive micro-relationships or Ornstein-Uhlenbeck processes, one can obtain various seasonal long memory Gaussian models. The investigation concerns the discrete as well as the continuous time setting. In both situations the precise asymptotic behaviour of the covariance is studied. The regularity of sample paths is evaluated when possible.     

Comprehensive analysis of vitamin E constituents in human plasma by liquid chromatography-mass spectrometry

The present paper describes the development and validation of a normal-phase liquid chromatography-mass spectrometry (NP-HPLC-MS) method for the screening and quantification of vitamin E constituents in human plasma and food matrixes. Liquid-liquid extraction combined with isotope dilution was applied to extract the lipophilic target analytes. Baseline separation of alpha-tocopherylacetate, alpha-tocopherol, alpha-tocotrienol, alpha-tocopherylquinone, beta-tocopherol, gamma-tocopherol, beta-tocotrienol, gamma-tocotrienol, delta-tocopherol, and delta-tocotrienol was achieved utilizing a normal-phase amine column operated with n-hexane and 1,4-dioxane as solvents. Detection was achieved by positive-ion atmospheric-pressure chemical ionization (APCI). Key features of the method are lower limits of detection, 3-51 nmoles/L; lower limits of quantification, 8-168 nmoles/L; linearity coefficients, 0.9778-0.9989; linear ranges, 0.01-29 micromol/L; recoveries, 53-92%; accuracies, 99-103%; intraday precisions, 2-17%; interday precisions, 5-18%; and suppression values, 0-29%. Fragmentation of tocopherols was studied by tandem mass spectrometry, and a fragmentation scheme for tocotrienols/tocopherols is postulated. Neutral-loss and precursor-ion scan experiments were performed for targeted discovery of oxidation products of tocopherols in human blood and fish oil, the latter being an important food component. The presented data suggest that this method will help to expand the number of quantified/discovered vitamin E constituents detected in food products and analyzed during human/animal trials in order to give a more comprehensive picture to nutritionists about the fate of vitamin E.     

The C-Terminal Domain of LRRK2 with the G2019S Substitution Increases Mutant A53T α-Synuclein Toxicity in Dopaminergic Neurons In Vivo

Alpha-synuclein (α-syn) and leucine-rich repeat kinase 2 (LRRK2) play crucial roles in Parkinson’s disease (PD). They may functionally interact to induce the degeneration of dopaminergic (DA) neurons via mechanisms that are not yet fully understood. We previously showed that the C-terminal portion of LRRK2 (ΔLRRK2) with the G2019S mutation (ΔLRRK2^G2019S) was sufficient to induce neurodegeneration of DA neurons in vivo, suggesting that mutated LRRK2 induces neurotoxicity through mechanisms that are (i) independent of the N-terminal domains and (ii) “cell-autonomous”. Here, we explored whether ΔLRRK2^G2019S could modify α-syn toxicity through these two mechanisms. We used a co-transduction approach in rats with AAV vectors encoding ΔLRRK2^G2019S or its “dead” kinase form, ΔLRRK2^DK, and human α-syn with the A53T mutation (AAV-α-syn^A53T). Behavioral and histological evaluations were performed at 6- and 15-weeks post-injection. Results showed that neither form of ΔLRRK2 alone induced the degeneration of neurons at these post-injection time points. By contrast, injection of AAV-α-syn^A53T alone resulted in motor signs and degeneration of DA neurons. Co-injection of AAV-α-syn^A53T with AAV-ΔLRRK2^G2019S induced DA neuron degeneration that was significantly higher than that induced by AAV-α-syn^A53T alone or with AAV-ΔLRRK2^DK. Thus, mutated α-syn neurotoxicity can be enhanced by the C-terminal domain of LRRK2^G2019 alone^, through cell-autonomous mechanisms.     

Transformation of microporous titanium glycolate nanorods into mesoporous anatase titania nanorods by hot water treatment

High surface area titanium glycolate microporous multi-faceted nanorods were synthesized from the reaction of titanium alkoxides (Ti(OEt)₄, Ti(O ⁱ Pr)₄, or Ti(O ⁿ Bu)₄) with ethylene glycol, using a sol–gel reflux method. The specific surface area of the as-synthesized titanium glycolate nanorods obtained from Ti(OEt)₄ is ~480 m²/g. A hot water treatment at 90 °C for 1 h transformed the titanium glycolate microporous nanorods into mesoporous anatase TiO₂ nanorods. The shape of the nanorods was conserved after hot water treatment and the microporous to mesoporous transformation took place without significant change in the surface area (477 m²/g). Micro Raman spectroscopy, scanning electron microscopy, transmission electron microscopy, X-ray diffraction, solid state NMR, and nitrogen adsorption/desorption were used to characterize the samples. As a demonstration of potential applications, the thus formed mesoporous anatase TiO₂ nanorods were tested for their photocatalytic efficiency in the degradation of crystal violet, and a photodegradation mechanism is proposed.     

Using truncated relaxation spectra in the simulation of viscoelastic flows

The simulation of polymer flows is a complicated problem. One of the limiting factors is the degree to which elasticity plays an important role in the flow. For a given constitutive equation and numerical technique, a higher material relaxation time will result in a lower maximum deformation rate for which convergence is possible. Since industrial processes typically involve large deformation rates, a practical way to allow their simulation is to truncate the longest relaxation times. In this work the Leonov constitutive equation was used to simulate flow through an abrupt contraction. The possibility of truncating the relaxation spectrum was explored and the impact of using truncated spectra on simulations is described. Finally, we propose a technique for obtaining a truncated relaxation spectrum that will be useful for flow simulations.