Two‐dimensional non‐Newtonian injection molding with a new control volume FEM/volume of fluid method

A new method based on volume of fluid for interface tracking in the simulation of injection molding is presented. The proposed method is comprised of two main stages: accumulation and distribution of the volume fraction. In the first stage the equation for the volume fraction with a noninterfacial flux condition is solved. In the second stage the accumulated volume of fluid that arises as a consequence of the application of the first one is dispersed. This procedure guarantees that the fluid fills the available space without dispersion of the interface. The mathematical model is based on two‐phase transport equations that are numerically integrated through the control volume finite element method. The numerical results for the interface position are successfully verified with analytical results and numerical data available in the literature for one‐dimensional and two‐dimensional domains. The transient position of the advance fronts showed an effective and consistent simulation of an injection molding process. The nondispersive volume of fluid method here proposed is implemented for the simulation of nonisothermal injection molding in two‐dimensional cavities. The obtained results are represented as transient interface positions, isotherms and pressure distributions during the injection molding of low density polyethylene. Copyright © 2012 John Wiley & Sons, Ltd.     

Frequency decay for Navier–Stokes stationary solutions

We consider stationary Navier–Stokes equations in ${\mathbb{R}}^3$ with a regular external force and we prove the exponential frequency decay of the solutions. Moreover, if the external force is small enough, we give a pointwise exponential frequency decay for such solutions. If a damping term is added to the equation, a pointwise decay is obtained without the smallness condition over the force.     

Catalytic application of a nano-molten salt catalyst in the synthesis of biological naphthoquinone-based compounds

Research on Chemical Intermediates - In this investigation, a new application of 1H-imidazol-3-ium tricyanomethanide catalyst was explored. The catalyst presented a robust catalytic applicability...     

Effect of humidity in charge formation and transport in LDPE

Charge distribution and transport have been investigated in LDPE films with different humidity content under electric fields up to 130 MV/m. Pulsed electroacoustic measurements showed that, as water content increases, positive charge packets formation in the anode is enhanced and they propagate toward the cathode with higher transit speeds. Fits of surface potential decay measurements showed that charges in dry samples are injected directly into the volume, but the presence of moisture generates new trap centers in the surface of the material. This new trap level causes a charge accumulation on the surface, that gradually passes into the bulk. The observed behavior in development and propagation of charge packets are explained according to these results. Thermally stimulated depolarization current measurements showed a non-distributed relaxation associated to the new trap levels on the surface of the wet samples.     

Redispersible spray-dried nanocapsules for the development of skin delivery systems: proposing a novel blend of drying adjuvants

This study proposes a novel blend of drying adjuvants (lactose and polyvinylpyrrolidone) as an approach to produce dispersible powders containing nanocapsules for the development of skin delivery systems. Hydrogels were produced with liquid nanocapsules and spray-dried powders. Nanoparticle recovery was obtained after powder aqueous redispersion. No influence of the intermediate product was observed on the hydrogel properties and on the drug release profile. The novel blend of drying adjuvants is a smart approach to obtain dried nanocapsules with excellent aqueous redispersion and to maintain the drug release profile of the original suspension in the design of novel skin delivery systems.     

A robust and hierarchical approach for the automatic co-registration of intensity and visible images

This paper presents a new robust approach to integrate intensity and visible images which have been acquired with a terrestrial laser scanner and a calibrated digital camera, respectively. In particular, an automatic and hierarchical method for the co-registration of both sensors is developed. The approach integrates several existing solutions to improve the performance of the co-registration between range-based and visible images: the Affine Scale-Invariant Feature Transform (A-SIFT), the epipolar geometry, the collinearity equations, the Groebner basis solution and the RANdom SAmple Consensus (RANSAC), integrating a voting scheme. The approach presented herein improves the existing co-registration approaches in automation, robustness, reliability and accuracy.     

Ruthenium Complex “Light Switches” that are Selective for Different G‐Quadruplex Structures

Recognition and regulation of G‐quadruplex nucleic acid structures is an important goal for the development of chemical tools and medicinal agents. The addition of a bromo‐substituent to the dipyridylphenazine (dppz) ligands in the photophysical “light switch”, [Ru(bpy)₂dppz]²⁺, and the photochemical “light switch”, [Ru(bpy)₂dmdppz]²⁺, creates compounds with increased selectivity for an intermolecular parallel G‐quadruplex and the mixed‐hybrid G‐quadruplex, respectively. When [Ru(bpy)₂dppz‐Br]²⁺ and [Ru(bpy)₂dmdppz‐Br]²⁺ are incubated with the G‐quadruplexes, they have a stabilizing effect on the DNA structures. Activation of [Ru(bpy)₂dmdppz‐Br]²⁺ with light results in covalent adduct formation with the DNA. These complexes demonstrate that subtle chemical modifications of Ru^II complexes can alter G‐quadruplex selectivity, and could be useful for the rational design of in vivo G‐quadruplex probes.