Time-Dependent Quantum-Mechanical Approaches to the Continuous Spectrum: Scattering Resonances in a Finite Box

Several novel aspects of scattering resonances are studied. An expression, valid for a finite box, relating the continuum phase shift with the energy shift and unperturbed level separation is proposed and applied to obtain the resonance parameters. The effect of the resonance on propagating a wavepacket in imaginary time is studied. It is observed that the resonance strongly affects the cumulants of the energy distribution. In particular, a local minimum of the first derivative of the energy with respect to time (proportional to the second cumulant) serves to estimate the resonance energy and wavefunction. Once the estimate is known, the autocorrelation function is used to evaluate the resonance width. Alternatively, a new iterative approach is developed that is capable of selectively yielding an arbitrary band of energy eigenvalues and eigenfunctions on a grid. This method is applied to give those energy levels that are of interest for the discrete computation of the resonant phase shift, i.e., those close to resonance. Exact (analytical) and approximate results are in good agreement for a particular separable potential model in one dimension. These methods can be extended to realistic potentials in higher dimensions.     

Variation of poly(vinylidene fluoride) morphology due to radial cold flow in a flexible pipe

A subsea flexible pipe containing isotropic poly(vinylidene fluoride) (PVDF) layers is subjected to rapid decompression after being put in pressurized equilibrium with a fluid containing supercritical CO₂. The PVDF layers have flowed radially into gaps of adjacent metallic coils forming whitened noses. Microbeam small‐angle X‐ray scattering (SAXS) scanning reveals a considerable morphological gradient in the polymer layers. PVDF layers (inner: wear, outer: barrier) in two zones (undamaged and damaged) are scanned. Far from noses and damage zone, the samples are isotropic without voids. Their morphological parameters are determined and compared to virgin material. Approaching the noses, the structure turns into highly oriented microfibrils perpendicular to the local flow into the gaps. Here, voids extend parallel to the microfibrils. At edges of the metallic structure, they turn more perpendicular to the layer. Crystallite orientation extends out to both sides of the whitened nose regions, but in the undamaged samples, tilting of the orientation direction and void‐formation are restricted to the white regions: successive mechanisms of cold drawing are mapped into space. Under the damaged spot, voids and crystallite orientation extend through the entire layer. POLYM. ENG. SCI., 55:2869–2877, 2015. © 2015 Society of Plastics Engineers     

Assessment of Novel Water-Borne Coatings Obtained from Composite Latex Particles and Reinforced with TiO2 Nanotubes

Novel, environmentally friendly waterborne coatings were obtained from the filmification of nanostructured latex particles reinforced with inorganic nanotubes. The latex used to form the coatings consists of core-shell particles with a shell functionalized with different amounts of acrylic acid (AA). This external polymer layer was doped, in some cases, with TiO₂ nanotubes at three different concentrations: 100, 500 and 1000 ppm. The composite particles were synthesized in two steps by semi-continuous emulsion polymerization at 75°C. A series of films was prepared by employing core-shell particles with different sizes, core cross-linking and shell functionalization. The coatings obtained were characterized by infrared spectroscopy (FTIR), tapping mode atomic force microscopy (TM-AFM), scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and thermogravimetrical analysis (TGA). Drying rates and tests were also performed to further evaluate these films. It was observed that the addition of small amounts of TiO₂ nanotubes contributes to improve the application properties, mainly adhesion to metallic substrates and water impermeability. The resistance to thermal degradation was also strongly increased, as showed by the DSC and TGA analyses.     

A bi‐criterion optimization approach for the design and planning of hydrogen supply chains for vehicle use

In this article, we address the design of hydrogen supply chains for vehicle use with economic and environmental concerns. Given a set of available technologies to produce, store, and deliver hydrogen, the problem consists of determining the optimal design of the production‐distribution network capable of satisfying a predefined hydrogen demand. The design task is formulated as a bi‐criterion mixed‐integer linear programming (MILP) problem, which simultaneously accounts for the minimization of cost and environmental impact. The environmental impact is measured through the contribution to climate change made by the hydrogen network operation. The emissions considered in the analysis are those associated with the entire life cycle of the process, and are quantified according to the principles of Life Cycle Assessment (LCA). To expedite the search of the Pareto solutions of the problem, we introduce a bi‐level algorithm that exploits its specific structure. A case study that addresses the optimal design of the hydrogen infrastructure needed to fulfill the expected hydrogen demand in Great Britain is introduced to illustrate the capabilities of the proposed approach. © 2009 American Institute of Chemical Engineers AIChE J, 2010     

A Solvent‐Free Dispersion Method for the Preparation of PET/MWCNT Composites

A simple, easily accessible solvent‐free method for the dispersion of MWCNTs into PET is proposed, based on the preparation of a microparticulate polymer/nanotube masterbatch via cryogenic impact‐milling and its subsequent melt blending with the bulk polymer. Thermal and mechanical properties of nanocomposites prepared using this method were evaluated as a function of nanotube concentration. Thermal stability was improved, and superior crystallization behavior of PET in the nanocomposites was observed. Significant improvements of around 25% in tensile strength and tensile modulus of the nanocomposites was achieved using this strategy, with only 0.25 wt.‐% MWCNT, compared to previous literature data where 1 wt.‐% MWCNT was employed.

     

Gene Therapy in HIV‐Infected Cells to Decrease Viral Impact by Using an Alternative Delivery Method

The ability of dendrimer 2G‐[Si{O(CH₂)₂N(Me)₂⁺(CH₂)₂NMe₃⁺(I^?)₂}]₈ (NN16) to transfect a wide range of cell types, as well as the possible biomedical application in direct or indirect inhibition of HIV replication, was investigated. Cells implicated in HIV infection such as primary peripheral blood mononuclear cells (PBMC) and immortalized suspension cells (lymphocytes), primary macrophages and dendritic cells, and immortalized adherent cells (astrocytes and trophoblasts) were analyzed. Dendrimer toxicity was evaluated by mitochondrial activity, cell membrane rupture, release of lactate dehydrogenase, erythrocyte hemolysis, and the effect on global gene expression profiles using whole‐genome human microarrays. Cellular uptake of genetic material was determined using flow cytometry and confocal microscopy. Transfection efficiency and gene knockdown was investigated using dendrimer‐delivered antisense oligonucleotides and small interfering RNA (siRNA). Very little cytotoxicity was detected in a variety of cells relevant to HIV infection and erythrocytes after NN16 dendrimer treatment. Imaging of cellular uptake showed high transfection efficiency of genetic material in all cells tested. Interestingly, NN16 further enhanced the reduction of HIV protein 24 antigen release by antisense oligonucleotides due to improved transfection efficiency. Finally, the dendrimer complexed with siRNA exhibited therapeutic potential by specifically inhibiting cyclooxygenase‐2 gene expression in HIV‐infected nervous system cells. NN16 dendrimers demonstrated the ability to transfect genetic material into a vast array of cells relevant to HIV pathology, combining high efficacy with low toxicity. These results suggest that NN16 dendrimers have the potential to be used as a versatile non‐viral vector for gene therapy against HIV infection.     

Technical–economic evaluation of a small-scale model plant for the manufacture of pine glue laminated timber

A small-scale glue laminated timber (GLT) model plant, capable of producing an average of 880 linear m of lamellas per day, approximately 1500 m³/year, located in Castilla y León, Spain, was technically and economically evaluated. The production of such plant is aimed at substituting imports of GLT manufactured from spruce in Central Europe. The total investment considered for this theoretical operation was 455 k€. The raw material proposed was Pinus sylvestris classified according to UNE 56544 as ME-2. The external lamellas were defined as ME-1, upgraded from ME-2 by the removal of knots and deformations, which gives an average block length of 1825 and 3800 mm for external and internal lamellas, respectively. The effective stiffness of such configuration was modeled, rendering beams that could be assigned to class resistance GL24. Production costs were 770 k€, 52% of which were timber as raw material. The volume of production is affected by the combination of products manufactured; therefore, this variable was presented as a function of economic result, defining zones of product-mix that would be economically unfeasible, feasible with reservations, and feasible. The products to be manufactured were straight beams, 6-m long, of 9 different cross-sections, varying from 80?×?120 mm² to 200?×?600 mm². Additionally, production volume, wood cost, and block length are identified as critical parameters for the sensitivity analysis of the plant. Considering a wood cost for ME-2 of 220 €/m³, the plant must operate at 70% of its capacity to be economically feasible. The economic result of the operation increases proportionally to block length. The plant generates an EBIT of 51 k€, PNV of 415 k€ (discount rate of 4%), and an IRR of 19%.

     

Rheology of tannin-added phenol formaldehyde adhesives for plywood

2 adhesive consumption in double glue line, which is significantly lower than the aprox. 400 g/m² allowed by commercially available phenol-formaldehyde adhesives. The adhesives prepared with resols containing 36% reactive solids, the tannins representing aprox. 20%, has permitted the preparation of eucalyptus plywood boards exceeding the requirements of the European norm for exterior grade plywood.

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2 je doppelter Klebeline erlaubt. Dies ist bedeutend niedriger als die etwa 400 g/m², die bei kommerziell erh?ltlichen Harzen n?tig sind. Die hier hergestellten Harze enthalten etwa 36% reaktive Harze, wovon ca. 20% Tannine darstellen. Mit diesen Harzen konnten Eukalyptus-Sperrh?lzer hergestellt werden, welche die Anforderungen der europ?ischen Normen für Au?enverwendung übersteigen.

     

Detection of clenbuterol in beef meat,liver and kidney by mid‐infrared spectroscopy (FT‐Mid IR) and multivariate analysis

Mid‐infrared spectroscopy (FT‐Mid IR) coupled with multivariate analysis was used to predict clenbuterol in beef meat, liver and kidney. A SIMCA model was also developed to discriminate between pure (beef meat, liver and kidney) and spiked with clenbuterol samples (beef meat‐clenbuterol, liver‐clenbuterol and kidney‐clenbuterol). The best models to predict clenbuterol concentrations were obtained using the partial least squares algorithm (PLS) with a R² > 0.9 and SEC and standard error of prediction <0.296 and 0.324, respectively. The SIMCA model used to discriminate pure and spiked with clenbuterol samples showed 100% correct classification rate. Methods detection limit was 2 μg kg^?1. FT‐Mid IR coupled with chemometrics could be a simple and rapid screening tool for monitoring clenbuterol in beef meat, liver and kidney implicated in food poisoning. This method could be use for screening purposes.