Crystallization Kinetics and Dielectric Properties of Fresnoite BaO–TiO2–SiO2 Glass–Ceramics

Nucleation and crystallization kinetics of fresnoite (Ba₂TiSi₂O₈) crystals in BaO–TiO₂–SiO₂ glasses have been explored for dielectric applications. The volume fractions crystallized at different temperatures and times were tracked by XRD analysis. The activation energy of crystallization was estimated from DTA results to be about 528 kJ/mol, which is consistent with the value obtained by XRD results. The Avrami parameter values calculated at different temperatures from DTA results were found to be between 3.2 and 3.9, indicating that the growth is three dimensional and the mechanism of growth is interface-controlled. Additionally, because of compositional similarities, the dielectric contrast between the glass (ɛ_r∼15) and the resulting glass–ceramic (ɛ_r∼18) was minimal.     

The Influence of Drug Solubility and Particle Size on the Pellet Formulation in a Rotoprocessor

ABSTRACT

Pellets containing drugs of different properties were prepared in a Rotoprocessor in order to study changes in the formulation process and resulting pellet characteristics. Diltiazem hydrochloride, diclofenac sodium, and theophylline were chosen as model drugs. Pellet size distribution, sphericity, density, hardness, friability, and repose angle were determined using standard methods. The amount of water as a wetting agent necessary for successful pellet formulation was observed for each sample and changed depending on drug solubility, concentration, and particle size. The pelletization of freely soluble diltiazem hydrochloride required 24.8–23.1% of the wetting agent and its amount decreased as the drug concentration increased. The demand for water in the formulation of theophylline pellets was 31.0–34.4% and it increased with increasing drug concentration. The pellet samples containing both drugs were easy to prepare. However, the cohesion of micronized diclofenac sodium particles negatively influenced both the pellet size distribution and the formulation process itself. When the drug concentration exceeded 40%, it was not possible to produce pellets of an appropriate size and the process was not reproducible.     

Steady-state performance and chemical efficiency of Microbial Electrolysis Cells

The objective of this paper was to study MEC performance at steady-state conditions in continuous mode and to analyse MEC performance in terms of chemical efficiency. At steady-state operation, a current density of 10.2 A m⁻² (applied voltage 1.0 V) for a set-up with an AEM was produced, compared to 7.2 A m⁻² for a set-up with a CEM. For all applied voltages, total internal resistance for the AEM configuration was lower than or the CEM configuration. Therefore, energy input for the AEM configuration is lower than for the CEM configuration. In case a CEM is used, the conductivity in the cathode reaches high values: >130 mS cm⁻¹. This conductivity is mainly caused by the presence of Na⁺ (7.8 g L⁻¹), K⁺ (12.2 g L⁻¹) and OH⁻ (8.3 g L⁻¹). Furthermore, MECs perform better at high buffer and electrolyte concentrations. However, as current density does not increase proportionally with increase in chemicals, the effectiveness of chemical addition decreases when more chemicals are added. Therefore, addition of chemicals and buffer does not necessarily enhance performance but increases operational costs.     

Seeing the bond: Acoustic imaging of seals in medical cartridges

It is important to be able to check the quality of seal, and this article looks at the use of acoustic micro imaging to inspect the bonding of a film t     

Truss layout optimization within a continuum

The present work extends truss layout optimization by considering the case when it is embedded in a continuum. Structural models often combine discrete and continuum members and current requirements for efficiency and extreme structures push research in the field of optimization. Examples of varied complexity and dimensional space are analyzed and compared, highlighting the advantages of the proposed method. The goal of this work is to provide a simple formulation for the discrete component of the structure, more specifically the truss, to be optimized in presence of a continuum.     

After a Terrorist Attack: Challenges for Political and Administrative Leadership in Norway

This article addresses the challenges that the terrorist attacks on 22 July 2011 in Norway created for central government and, more particularly, for the political and police leadership. The emphasis is on ‘meaning making’, focusing on how the leaders played out their reactions in the media and towards the public. When explaining the different aspects of crisis management, we draw on three organizational perspectives: emphasizing the importance of myths and symbols, formal organization and cultural–institutional traditions. The analysis is based on qualitative content analysis of central policy documents, parliamentary debates and documents, speeches made by central actors and mass media coverage in the year following the attacks. A main finding is that the response to the terrorist attacks is characterized by complex interactions between mutually influential factors, by dynamics between symbolic factors, on one hand, and structural and cultural influences, on the other.