975 research outputs found

    Investigation of the Structure of Alkyne Self-Assembled Monolayers on Gold and the Development of Matrix-Enhanced Secondary Ion Mass Spectrometry Methods

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    Characterization of thin films is critical to the understanding of many technological and biological processes. The focus of this dissertation is to develop methods to characterize very low concentration species present on surfaces. A reflection adsorption infrared spectroscopy: RAIRS) system was constructed and tested. The instrument comprises an Fourier transform infrared: FTIR) spectrometer, an optical pathway and a vacuum chamber. The RAIRS system is designed to investigate in situ the interaction of vapor-deposited metals and gases, such as CVD precursors, with organic thin films, and so a vacuum chamber is required. To accommodate the vacuum chamber, an external IR optical pathway was designed and assembled because there was not enough room in the internal optical pathway of the FTIR spectrometer. The synthesis and characterization of terminal alkyne monolayers: TAMs) adsorbed on gold was investigated by RAIRS, single wavelength ellipsometry, time-of-flight secondary ion mass spectrometry: TOF SIMS) and x-ray photoelectron spectroscopy: XPS). TAMs have the potential to transform surface functionalization for many technological applications because they have increased temperature stability and electrical conductance. However, the data suggest that TAMs are not well-ordered and can be oxidized, which may limit their application. For TAMs with less than 11 methylene units in the backbone, the adsorbed layer is highly disordered, oxidized and has a multilayer structure. Longer chain length TAMs form disordered monolayers on gold. As the methylene chain length increases, the conformational order of the TAMs increases with the alkynes in an upright conformation and bound to the surface via a Au-C¡ÕC- bond. The use of room temperature ionic liquids: ILs) as matrices in TOF SIMS was examined to further characterize biological thin films. The data indicate that the secondary ion intensities of lipids, steroids, peptides, proteins and proteins are significantly enhanced using IL matrices. Secondary ion enhancements of at least an order of magnitude are typically observed. Limits of detection are also greatly improved. For example, the limits of detection of 1,2-dipalmityl-sn-glycero-phosphocholine: DPPC) and 1,2-dipalmityl-sn-glycero-phosphoethanolamine: DPPE) were at least two orders of magnitude better. The data also show that ILs are suitable matrices for imaging SIMS. The IL matrices did not cause changes to the sample surface; no ¡°hot spots¡± were observed. The mechanism of the secondary ion intensity enhancements using IL matrices was then investigated to optimize use in characterization. Only protic ILs, which are formed by the transfer of a proton from a Br©ªnsted acid to base, were observed to increase analyte signals. The matrix enhancement mechanism therefore involves the transfer of protons from, or to, the analyte, to, or from the matrix. The magnitude of the analyte signal enhancements is dependent on the chemistry of the matrix cation, anion and analyte. The pKa of the matrix acid and base do not appear to have a strong effect on the ion-intensity enhancements. The results also indicate that the chemical identity of the matrix anion has a stronger effect on analyte signal enhancements than the matrix cation

    Two-Focus Fluorescence Correlation Spectroscopy

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    Fluorescence Correlation Spectroscopy (FCS) has been invented more than 30 years ago and experienced a renaissance after stable and affordable laser sources and low-noise single-photon detectors have become available. Its ability to measure diffusion coefficients at nanomolar concentrations of analyte made it a widely used tool in biophysics. However, in recent years it has been shown by many authors that aberrational (e.g. astigmatism) and photophysical effects (e.g. optical saturation) may influence the result of an FCS experiment dramatically, so that a precise and reliable estimation of the diffusion coefficient is no longer possible. In this thesis, we report on the development, implementation, and application of a new and robust modification of FCS that we termed two-focus FCS (2fFCS) and which fulfils two requirements: (i) It introduces an external ruler into the measurement by generating two overlapping laser foci of precisely known and fixed distance. (ii) These two foci and corresponding detection regions are generated in such a way that the corresponding molecule detection functions (MDFs) are sufficiently well described by a simple two-parameter model yielding accurate diffusion coefficients when applied to 2fFCS data analysis. Both these properties enable us to measure absolute values of the diffusion coefficient with an accuracy of a few percent. Moreover, it will turn out that the new technique is robust against refractive index mismatch, coverslide thickness deviations, and optical saturation effects, which so often trouble conventional FCS measurements. This thesis deals mainly with the introduction of the new measurement scheme, 2fFCS, but also presents several applications with far-reaching importance

    R116C mutation of cationic trypsinogen in a Turkish family with recurrent pancreatitis illustrates genetic microheterogeneity of hereditary pancreatitis

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    Hereditary pancreatitis is due to heterozygosity for gain-of-function mutations in the cationic trypsinogen gene which result in increased levels of active trypsin within pancreatic acinar cells and autodigestion of the pancreas. The number of disease-causing defects is generally considered to be low. To gain further insight into the molecular basis of this disorder, DNA sequence analysis of all five exons was performed in 109 unrelated patients with idiopathic chronic pancreatitis in order to determine the variability of the underlying mutations. Two German females and one German male were carriers of the most common N291 and R122H mutations (trypsinogen numbering system). In a Turkish proband, an arginine (CGT) to cysteine (TGT) substitution at amino acid position 116 was identified. Family screening demonstrated that the patient had inherited the mutation from his asymptomatic father and that he had transmitted it to both of his children, his daughter being symptomatic since the age of 3 years. In addition, a German male was found to be a heterozygote for a D100H (GAC-->CAC) amino acid replacement. Our data provide evidence for genetic heterogeneity of hereditary pancreatitis. The growing number of cationic trypsinogen mutations is expected to change current mutation screening practices for this disease

    Mutter, Gattin, Mörderin - Eine Untersuchung zu Weiblichkeit und weiblicher Kriminalität in Recht und Literatur.

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    In der vorliegenden Dissertation wird die Darstellung von Weiblichkeit und weiblicher Kriminalität in Recht und Literatur anhand der beiden "typisch weiblichen" Delikttypen Kindsmord und Giftmord mittels Gegenüberstellung authentischer Rechtsfälle und deren literarischer Verarbeitung untersucht

    Untersuchungen zur Neurologie und zerebralen Inflammation nach tief hypothermem Kreislaufstillstand der Ratte: Einfluss der Wiedererwärmungsgeschwindigkeit

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    Despite considerable progress in medicine, and the adapt use of CPB with DHCA, congenital heart defects are still considered a challenge for surgery. Today`s scientific research focuses on CPB with DHCA and the possible cerebral inflammatory reaction, contributing to the often adverse neurologic and neurocognitive outcome following CPB with DHCA. Aim o f this study is to investigate the impact of the rate and duration of rewarming have on postoperative neurologic function, histologic outcome and cerebral inflammatory reaction in a clinically relevant animal model of CPB with 45 min of DHCA in the rat. 20 male Sprague Dawley rats (330 – 390 g) were anaesthetized, endotracheally intubated and ventilated with 2 to 2.5 Vol % Isoflurane in 40 Vol % O2. For pain management all animals received repititive 5µg boli of Fentanyl. Animals were surgically cannulated as follows: the A. sacralis mediana for arterial inflow during CPB, the taking of blood samples and drug administration. The A. epigastrica superficialis for blood pressure monitoring and the V. jugularis externa and V. cava cranialis for venous drainage during CPB. During the cooling phase anaesthesia was maintained with 0.8 to 1Vol % Isoflurane and Cisartracurium was given additionally for muscle relaxation (1,6mg/h). To cool rats down to a rectal temperature of 15 – 18 °C within 30 min, cooling blankets, ice bags and a heat exchanger in the oxygenator were used. At 15 – 18 °C, CPB and anaesthesia were terminated for 45 minutes and the venous drainage was opened every ten minutes to allow the animals to exsanguinate to prevent a right heart dilatation. Rats were then randomly assigned to one of two rewarming groups (n = 10): with reinstitution of CPB and anaesthesia, one group was rewarmed slowly over 40 minutes and a second group fast over 20 minutes back to a rectal temperature of 35.5 °C. When reaching 35.5 °C, animals were weaned from CPB, and anaesthesia was maintained for one hour folllowing CPB. During that time the blood left in the circuit was collected, centrifuged, adjusted with HES and calcium to a hematocrit below 50% and returned to raise the animal`s hematocrit above 30%. Anaesthesia was terminated one hor following CPB. Animals were extubated when showing sufficient spontaneous breathing and allowed to recover under observation in an oxygen enriched environment. Rats were neurologically tested one day prior to CPB with DHCA as well as on the postoperative day. 24 hours following the end of CPB, animals were sacrificed, their brains removed and deep frozen (-70 °C) for further analysis. H&E staining was performed using slices taken at bregma –0.3 and –3.3 to investigate the histological damage in the Gyrus cinguli, Striatum, motor cortex, Hippocampus and Vermis. NF-kB- positive neurons were labelled with an immunhistochemical double staining and counted using light microscopy. Inflammatory parameters TNF-α, COX-2 and I-kB were evalueted using Wetsern Blotting. For the first time this study compares the neurologic outcome following two different rewarming protocols after DHCa in a clinically relevant animal model of CPB with DHCA. Unexpectedly, a better neurologic outcome is seen after fast rewarming. Although results for histology and immunehistochemistry show higher amounts of eosinohilic and NF-kB- positive neurons in this group. Western Blot also shows increased levels of inflammatory parameters COX-2 and I-kB in the fast rewarming group. These findings suggest that the rewarming rate alone is not the chief cause for an adverse neurological out-come after CPB with DHCA. Further studies concerning the mechanisms leading to adverse neurologic outcome and cerebral inflammatory reaction following CPB with DHCA are required.„Neurologische Defizite und zerebrale Inflammation nach tief hypothermem Kreislaufstillstand der Ratte: Einfluss der Wiedererwärmungsgeschwindigkeit“ In einem Zeitalter großen medizinischen Fortschritts gehören kongenitale Herzdefekte trotz routinemäßiger Anwendung der Extrakorporalen Zirkulation (EKZ) mit tief hypothermem Kreislaufstillstand (DHCA) zu den chirurgischen Herausforderungen. Da die Inzidenz neuro-logischer Defizite nach herzchirurgischen Eingriffen dennoch hoch ist, wird dieser mit EKZ und DHCA assoziierten Morbidität vermehrt Aufmerksamkeit geschenkt. Im Fokus heutiger wissenschaftlicher Forschung stehen in diesem Zusammenhang die mit DHCA notwendige Wiedererwärmung und etwaige zerebrale Entzündungsreaktionen. Ziel dieser Studie war es, den Einfluss der Wiedererwärmungsrate und –dauer auf die neurologische Funktion, die zerebrale Inflammation, sowie die Histologie in einem kliniknahen Modell der EKZ mit DHCA an der Ratte zu untersuchen. 20 männliche Sprague-Dawley Ratten (330 bis 390 g) wurden anästhesiert, intubiert und mit 2 bis 2,5 Vol % Isofluran in ca. 40 % Sauerstoff beatmet. Danach kanülierte man folgende Gefäße: die A. sacralis mediana, für den Anschluss an die EKZ, zur Rückgabe oxygenierten Blutes, der Blutentnahme und der Medikamentenapplikation, die A. epigastrica superficialis zur Blutdruckmessung, sowie die V. jugularis externa dextra und V. cava cranialis zur venösen Drainage während der EKZ. In der darauf-folgenden Abkühlungsphase wurde die Anästhesie mit 0,8 bis 1 Vol % Isofluran aufrecht-erhalten. Um eine Analgesie zu gewährleisten, erhiel-ten die Tiere repetitiv Fentanyl (5 μg Boli) und zur Relaxation 1,6 mg/h Cisatra-curium. In dieser Phase kühlte man die Tiere mit Hilfe von Kühlmatten, Eisbeuteln und dem Wärmetauscher der EKZ innerhalb von 30 Minuten auf eine rektale Temperatur von 15 bis 18 ºC. Mit Erreichen dieser Körpertemperatur wurde die EKZ beendet. Während des 45 minütigem, tief hypothermen Kreislaufstillstandes stellte man die Beatmung, sowie die Anästhesie ein. Die Tiere wurden randomisiert in zwei Wiedererwärmungsgruppen (n = 10) eingeteilt. Während die eine Gruppe langsam (40 Minuten) wiedererwärmt wurde, erwärmte man die andere Gruppe innerhalb von 20 Minuten (schnell) auf eine rektale Temperatur von 35,5 °C. Die Anästhesie erfolgte analog der Abkühlungsphase. Nach Ende der EKZ führte man die Beatmung noch für 1 Stunde weiter. In dieser Zeit retransfundierte man die Tiere mit Erythrozytenkonzentrat (bestehend aus abzentrifugierten Restblut aus der Herz-Lungen-Maschine, versetzt mit Hydroxyethylstärke und Calcium, Hämatokrit > 50%, um den Hämatokrit der Tiere über 30 % zu haben). Die Ratten wurden sowohl präoperativ (1 Tag vor OP) als auch postoperativ am nächsten Tag neurologisch untersucht und 24 Stunden nach erfolgter OP getötet. Die Hirne wurden in toto entnommen, eingefroren und histologisch mit Hämatoxylin-Eosin-Färbung und Immunhistochemie untersucht, um die Menge eosinophiler Zellen und die Menge NF-kB positiver Neurone zu ermitteln. Die Inflammationsparameter TNF-α, COX-2 und I-kB untersuchte man mit Western Blot. Die vorliegende Studie konnte erstmalig vergleichend das neurologische Outcome nach zwei verschiedenen Wiedererwärmungsstrategien nach EKZ mit tief hypothermen Kreislaufstillstand an einem kliniknahen Modell an der Ratte zeigen. Entgegen den eigenen Erwartungen konnte ein besseres neurologisches Ergebnis nach schneller Wiedererwärmung im Vergleich zur langsamen Wiedererwärmung festgestellt werden. Dennoch zeigte sich in den Ergebnissen der Histologie, der Doppelfärbung und des Western Blots eine vermehrte Schädigung der Neurone, sowie eine Erhöhung der Inflamma-tionsparameter nach schneller Wiedererwärmung. Die Pathomechanismen der zerebralen Inflammation nach DHCA, sowie der Einfluss der Reperfusion auf das neurologische Outcome und die komplexe Interaktion zwischen Wiedererwärmung, Reperfusion und in-flammatorischer Prozesse im Gehirn bedürfen weiteren Studien

    Media Pedagogical Professionalization of Teachers in a Mediatized Society: The Habitus Concept as a Link between Social Demands and Pedagogical Usage of Technology

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    Der Metaprozess der tiefgreifenden Mediatisierung führt zu neuen und veränderten Anforderungen an das pädagogische Medienhandeln von Lehrkräften. Um die Qualität des unterrichtlichen Medieneinsatzes zum Lernen mit und über Medien sicherzustellen, werden sowohl im pädagogischen Fachdiskurs als auch auf bildungspolitischer Ebene Kompetenzerwartungen an die professionelle Arbeit von Lehrpersonen formuliert. Empirische Ergebnisse zeigen, dass diese Erwartungen nicht mit dem Medieneinsatz von Lehrpersonen im Unterricht hinsichtlich Umfang und Qualität übereinstimmen (Drossel et al. 2019; Schaumburg et al. 2019). Die Frage, wie ein professionelles und pädagogisch angemessenes Medienhandeln im Unterricht befördert werden kann, wird im medienpädagogischen Diskurs unter vielfältigen Perspektiven thematisiert. Studien zum medialen Habitus zeigen, dass das implizite Wissen einen bedeutenden Einfluss auf das pädagogische Medienhandeln hat (Biermann 2009; Kommer 2010). Bei einer genaueren Betrachtung dieses Themenbereichs entstehen auf theoretischer Ebene allerdings Fragen zur Konzeption des Habitus und des impliziten Wissens. Insbesondere die Frage, wie das Konstrukt des Habitus mit den gesellschaftlichen Veränderungen einer tiefgreifenden Mediatisierung in Beziehung gesetzt werden kann, ist noch ungeklärt. Der vorliegende Artikel widmet sich dieser Fragestellung auf einer theoretischen Ebene, die einen Ausgangspunkt für weitere Diskussionen und für die empirische Forschung darstellen soll.The process of deep mediatization changes the requirements for the pedagogical usage of modern technology. To ensure the quality of teaching there are several competence models that describe for which purpose teachers should use technology. However, research shows that teachers don`t use technologies in extent and quality pedagogical or political expectations intend. In the mediapedagogical discourse, there is a wide discussion about how a pedagogical and professional usage of technology from teachers could be supported. The findings and discussions about the ‹medial habitus› are emphasizing the importance of unreflect knowledge for the usage of technology. However, on a theoretical perspective the concept of the habitus has many unclarified elements. Particularly, the relationship between the changing structure of society in context of a deep mediatization and the conception of the Habitus is an open question. This article discusses this question on a theoretical perspective, which could be a starting point for further discussion and research
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