Chemical Solution Deposition of Columnar-Grained Metallic Lanthanum Nitrate Thin Films

Columnar and (100)-oriented LaNiO₃ thin films were prepared on silicon substrates by a chemical solution deposition (CSD) process using a 0.05 M solution. By reducing the individual layer thickness to 10 nm, columnar LaNiO₃ films with a lateral grain size of ∼120 nm were obtained. The success of this approach required restricting the individual layer thickness to a value below the grain size observed for equiaxed films. This change in microstructure resulted in an improvement in conductivity. The columnar LaNiO₃ film with a thickness of 300 nm showed a resistivity of 4.5 × 10⁻⁵Ω·cm, which is lower by one order of magnitude than that of fine-grain equiaxed films that typically result from CSD methods.     

Influence of selective filling on rheological properties and phase inversion of two-phase polymer blends

We investigate the phase inversion of selectively filled polystyrene (PS)/poly(methyl methacrylate) (PMMA) blends prepared by melt mixing. As we have shown by transmission electron microscopy analysis and by the calculation of different selectivity criteria, the filler used (glass spheres of submicron dimensions) resides exclusively in the PMMA-phase and modifies its rheological properties correspondingly.Four blend series made of PS and PMMA with different filler content are analyzed for the location of phase inversion concentration, φ_PI, and the width of the cocontinuity interval, CCI, in the concentration range where cocontinuity is predominant. Upon addition of filler a shift of φ_PI to higher concentrations of the filled PMMA-phase has been observed. This shift is in agreement with the predictions of a recently proposed equation defining the phase inversion concentration as that concentration where the maximum of the blends' extra elasticity occurs. The qualitative morphological analysis of these blends confirms this result.Moreover, it was found that the cocontinuity interval is widened significantly at increased filler content. We explain the appearance of a wider CCI for filled blends on the basis of a slowdown of processes leading to morphology destruction. Corresponding Tomotika experiments (stability of fibrils) substantiate these findings.     

SCALING IN SITU BIOREMEDIATION PROBLEMS BY APPLICATION OF MULTIPHASE, MULTICOMPONENT TRANSPORT THEORY

A methodology for scaling in situ bioremediation problems is presented. This methodology is based on multiphase, muiticomponent transport theory and employs inspectional analysis and numerical sensitivity studies. A general mathematical model that describes subsurface aerobic biotransformation of organic chemical species in a multiphase setting is first presented. This general model is applied to the specific case of microbial enhanced vapor-vacuum extraction (MEVVE) in a one-dimensional zone of immobile liquids. The resulting simplified MEVVE model considers rate-dependent interphase mass transfer, a flowing gaseous phase, a single hydrocarbon pseudo-component, and either oxygen or hydrocarbon limited microbial activity. By inspectional analysis a set of dimensionless groups are derived that represent the various model parameters. A scries of numerical sensitivity studies are presented that examine the impact of selected dimensionless groups on overall system biotransformation rates. This analysis demonstrates that overall biotranformation rates can be significantly limited not only by insufficient transport of oxygen in the gaseous phase, but also by interfacial mass transfer resistance between nonaqueous phase liquid globules and adjacent fluids. Finally, an examination of the selected dimensionless groups reveals the parameter requirements for properly scaled MEVVE tests. These results indicate the need for further investigation of the importantance of fluid distributions in the pore space and their impact on the design of laboratory and field tests.     

Cardiac Arrhythmias and Sleep-Disordered Breathing in Patients with Heart Failure

The relationship between heart failure (HF), sleep-disordered breathing and cardiac arrhythmias is complex and poorly understood. Whereas the frequency of predominantly obstructive sleep apnea in HF patients is low and similar or moderately higher to that observed in the general population, central sleep apnea (CSA) has been observed in approximately 50% of HF patients, depending on the methods used to detect CSA and patient selection. Despite this high prevalence, it is still unclear whether CSA is merely a marker or an independent risk factor for an adverse prognosis in HF patients and whether CSA is associated with an increased risk for supraventricular as well as ventricular arrhythmias in HF patients. The current review focuses on the relationship between CSA and atrial fibrillation as the most common atrial arrhythmia in HF patients, and on the relationship between CSA and ventricular tachycardia and ventricular fibrillation as the most frequent cause of sudden cardiac death in HF patients.