Infrarot-Ellipsometrie-Untersuchungen zum Einfluss von Wärme und Feuchte auf organische Halbleiter sowie zum Einfluss der Morphologie von Goldfilmen auf ihre dielektrische Funktion

Die dielektrischen Funktionen von Dünnfilmen untersuchter, polykristalliner organischer Halbleiter, die sich aus Infrarotellipsometrie- (IRSE)-Messungen ermitteln lassen, sind raumrichtungsabhängig. Am Beispiel von Merocyanin wird gezeigt, dass durch einen Vergleich der dielektrischen Funktion mit quantenchemisch berechneten Schwingungsanregungen, die mittlere Orientierung der Moleküle in Dünnfilmen bestimmt werden kann. Eine Orientierungsänderung durch Erwärmen der Filme liefert eine Erklärung für die Verdopplung des Füllfaktors einer Merocyanin/C60-Solarzelle. An Dünnfilmen eines Naphthalindiimids wird nachgewiesen, dass der Einfluss von erhöhter Luftfeuchte und Temperatur zur Ausdehnung der Kristallite und zur stellenweise Entnetzung des genutzten SiO2/Si-Substrats führt. Hier werden die IRSE-Messungen, in denen sich eine Erhöhung der Molekülordnung parallel zur Substratoberfläche beobachten lässt, mit Rasterkraftmikroskopie- (AFM)-Aufnahmen kombiniert. Auf den Filmen aufbauende Transistoren zeigen einen starken Abfall des Stromflusses und die Zunahme einer unbeabsichtigten Dotierung mit der Lagerungszeit in erhöhter Feuchte und Wärme. In trockener Wärme kann die Dotierung reduziert werden. Für Polytriarylamin-Dünnfilme wird eine Oxidation bei Lagerung in erhöhter Temperatur nachgewiesen. Des Weiteren wird die Herstellung solcher Filme per Flexodruck untersucht, wobei sich Verunreinigungen in den Filmen finden lassen. Ergänzend wird gezeigt, dass die Modellierung von IR-Spektren rauer Goldfilme durch einen einfachen Drude-Oszillator zu einer effektiven Plasmafrequenz führt, die sich von derer glatter Filme unterscheidet und mit dem metallischen Volumenanteil eines effektiven Mediums aus Gold und Hohlräumen skaliert. Die Streurate hingegen erhöht sich mit sinkender Größe der in AFM-Bildern beobachteten Goldkristallite

Exploring the relationships between composite scores of disease severity, seizure-freedom and quality of life in Dravet syndrome

Background In Dravet syndrome (DS), a rare epileptic and developmental encephalopathy, the effectiveness of a new treatment is predominantly measured in terms of seizure frequency. However, this may not fully capture the impact of a treatment on the broader aspects of the syndrome and patients’ health-related quality of life (HRQoL). Using a previously published survey which collected data from DS patients and their carers on the broader manifestations of their syndrome, their HRQoL, and their experience of seizures, this study created composite measures of symptom severity to offer new perspectives on the multifaceted aspects of this rare condition. Methods Survey responses on the severity of physical and psychosocial symptoms were combined with independent assessments of disability and care need, to generate three composite symptom scores assessing the manifestations of DS (physical, psychosocial and care requirements). Variation in HRQoL was investigated in multiple regression analyses to assess the strength of association between each of these composite measures and three forms of seizure measures (seizure frequency, days with no seizures and longest interval without seizures), as experienced over a 4- and 12-week period. Results Composite scores were calculated for a cohort of 75 primarily paediatric patients who were enrolled in the study. Strong associations were found between each of the three composite symptom scores and each of the three seizure measures, with the regression coefficient on symptom score highly significant (p ≤ 0.001) in all nine comparisons. Separate regressions using predictors of HRQoL (Kiddy KINDL and Kid KINDL) as the dependent variable were inconclusive, identifying only behavioural/attention problems and status epilepticus as significant predictors of HRQoL. Conclusions These results allow the development of a composite score that may be useful in developing a clinical understanding of the severity of DS for an individual patient and establishing their treatment goals. Where measurement of long-term sequalae of disease is not feasible, such as clinical trials, correlation of the composite score with experience of seizures and seizure-free periods may allow a better contextualisation of the results of short-term assessments. Trial registration German Clinical Trials Register (DRKS), DRKS00011894. Registered 16 March 2017, http://www.drks.de/ DRKS00011894

Infrared Dielectric Function of Gold Films in Relation to Their Morphology

Though data concerning gold’s optical properties differ substantially in the literature, the causes for these discrepancies are poorly understood. Surface quality affects the optical response considerably, not only through crystal defects but also through the existing morphology. If optical data analysis is done under the assumption of ideally flat surfaces, the obtained dielectric function or dynamic conductivity and any model parameters represent an effective description that may differ from bulk values according to various preparation conditions. To show this finding in detail, we performed spectroscopic ellipsometry measurements of evaporated gold films in the mid-infrared range, below the onset of the interband transitions, and investigated the sample morphology by means of atomic force microscopy. This study yields effective Drude-model parameters that vary with film morphology over a range that includes most of the published values. Introducing a Bruggeman effective medium to model rough films as a mixture of bulk metal and empty volume makes it possible to find a relation between metal volume fraction and effective plasma frequency. In such a model, the plasma frequency and also the dielectric background resulting from interband transitions decrease as the fraction of empty volume inclusions increases. In contrast, while metal volume fraction is much less influential to relaxation time, the density of the gold crystallites’ grain boundaries yields a strong effect. We thus found a plasma frequency, relaxation rate, and dielectric background for the most ideal gold films at room temperature of 7.37(40) × 10⁴ cm^–1, 221(1) cm^–1, and 9.6(3), respectively

Orientation of Nonplanar Molecules in Polycrystalline Layers from Infrared Spectra: Core-Chlorinated Naphthalene Tetracarboxylic Diimides

By means of infrared spectroscopic ellipsometry in the range of 350–5000 cm^–1, the anisotropic dielectric functions of dichlorinated naphthalene diimide with fluoroalkyl chains (NDI-F), a novel high-performance n-type organic semiconductor, thin films were determined with high precision. Films of varying thicknesses (between 5 and 60 nm) evaporated in vacuum or spin coated from solution on different silicon wafers can all be described by the same anisotropic vibrational susceptibility, indicating weak dependence of the molecular orientation on processing procedure and film thickness for this material. It is shown how to determine the predominant molecular orientation by thorough comparison of ellipsometric measurements with calculations based on density functional theory. The method used additionally reveals subtle discrepancies between experiment and single molecule calculation which certainly arise from intermolecular interaction

Genome-wide Association Study Identifies 2 New Loci Associated With Anti-NMDAR Encephalitis

Background and Objectives To investigate the genetic determinants of the most common type of antibody-mediated autoimmune encephalitis, anti-NMDA receptor (anti-NMDAR) encephalitis. Methods We performed a genome-wide association study in 178 patients with anti-NMDAR encephalitis and 590 healthy controls, followed by a colocalization analysis to identify putatively causal genes. Results We identified 2 independent risk loci harboring genome-wide significant variants (p = 2.2), 1 on chromosome 15, harboring only the LRRK1 gene, and 1 on chromosome 11 centered on the ACP2 and NR1H3 genes in a larger region of high linkage disequilibrium. Colocalization signals with expression quantitative trait loci for different brain regions and immune cell types suggested ACP2, NR1H3, MADD, DDB2, and C11orf49 as putatively causal genes. The best candidate genes in each region are LRRK1, encoding leucine-rich repeat kinase 1, a protein involved in B-cell development, and NR1H3 liver X receptor alpha, a transcription factor whose activation inhibits inflammatory processes. Discussion This study provides evidence for relevant genetic determinants of antibody-mediated autoimmune encephalitides outside the human leukocyte antigen (HLA) region. The results suggest that future studies with larger sample sizes will successfully identify additional genetic determinants and contribute to the elucidation of the pathomechanism