Diffusion and adsorption of proteins in mesoporous environments

It is the main subject of this thesis to present a comprehensive study of the interaction between proteins and solid surfaces, especially the pore walls of nanoporous silica particles. This is complemented by an examination of the proteins\u27 diffusive behavior in porous aluminum oxide. The first part of this thesis attempts to validate the Stokes-Einstein equation for the diffusion of proteins through tubular pores in solid-state membranes. It further envisages means to separate proteins solely based on their tertiary structure. A comprehensive analysis of the protein adsorption behavior on silica surfaces constitutes the second part of this thesis. The complicated nature of the protein-silica interaction is confirmed and explained by a combination of several commonly used models. The findings thereof are used in the third part of this thesis, where competitive adsorption from protein mixtures on a silica substrate is studied. Effective selective binding of proteins from binary mixtures is achieved if the buffer solution is appropriately adjusted to the proteins electrochemical properties.Hauptgegenstand dieser Arbeit ist die umfassende Untersuchung der Wechselwirk- ungen zwischen Proteinen und Festkörperoberflächen, insbesondere den Poren- wänden nanoporöser Siliziumdioxidpartikel. Ergänzt wird dies um die Untersuchung des Diffusionsverhaltens von Proteinen in porösem Aluminiumoxid. Im ersten Teil dieser Arbeit wird die Gültigkeit der Stokes-Einstein-Gleichung für die Proteindiffusion durch zylindrische Festkörperporen überprüft. Darauf aufbauend wird die Möglichkeit untersucht, anderweitig identische Proteine einzig anhand ihrer Tertiärstruktur zu separieren. Eine umfassende Untersuchung der Wechselwirkung zwischen Proteinen und Siliziumdioxidoberflächen stellt den zweiten Teil dieser Arbeit dar. Die Komplexität dieser Wechselwirkung wird bestätigt und anhand einer Kombination verschiedener gängiger Modelle beschrieben. Die Ergebnisse hieraus fließen in den dritten Teil dieser Arbeit ein, in dem die selektive Adsorption verschiedener Proteine untersucht wird. Durch Anpassen der Pufferlösungen an die elektrochemischen Eigenschaften der verwendeten Proteine wird die effektive Separation binärer Mischungen demonstriert

Vom inneren Schelf zur Tiefsee: Ablagerungsräume am Westrand der antarktischen Halbinsel

Aim of this study was to describe and characterize three typical West Antarctic Peninsula continental margin depositional environments. Seismic, downhole and laboratory tools and techniques were applied to record physical and chemical proxies for a mulifacetted and differenciated understanding of the particular environments. 1) A detailed seismostratigraphic characterisation of the unique Antarctic inner and outer shelf along the passive margin of the West Antarctic Peninsula has been complemented by logging informations that are tied to the seismic profiles via a new continuous depth vs. velocity profile. Sealevel fall overcompensated by increased isostatic subsidence due to ice build-up that affected the continent and the adjacent shelfs is the most likely explanation for time synchronous start of topset preservation at ~2.8 Ma observed in Antarctic Peninsula and East Antarctic shelf records in conjunction with Nothern Hemnisphere Glaciation. 2) Seismostratigraphic Model of Palmer Deep based on seismic Deep Tow Boomer records. 3) Large mounts on the continental rise along the Antarctic Peninsula margin between 63°S and 69°S and within 200 km of the shelf break are interpreted as sediment drifts, separated by turbidity current channels. Using a special standardized moving window counting routine the spatial facies information data has been transformed into a regional Antarctic Peninsula ice volume indicator curve that is in good agreement with the Lear et al., 2000 data over the past 10 Ma. This regional ice volume curve for the Antarctic Peninsula is the most significant finding of this thesis. All evaluated proxy data prove that the early Pliocene was a time of reduced global- and Antarctic ice volume (-70%) and sea ice extent. Never before and after during the last 10 Ma was palaeo productivity higher at the rise than during this time. During the late Miocene the ice sheet was highly dynamic with frequent advances and retreats. Starting at 3.2 Ma in concert with the Northern Hemisphere Glaciation the ice sheet became a permanent feature occupying the shelf during most of the glacial half cycles

Das Kopftuchverbot in Deutschland - feministische Auseinandersetzungen

Seit 1998, als der Lehrerin Fereshta Ludin verwehrt wurde ihren Dienst mit Kopftuch anzutreten, entwickelte sich ein dichter Diskurs um die Bedeutung und die Vereinbarung des Kopftuchs mit feministischen Zielsetzungen und den staatlichen Strukturen der Schule in Deutschland. Diese Arbeit behandelt den feministischen Diskurs contra Kopftuch und pro Kopftuchverbot in der BRD und strukturiert die wichtigsten Argumentationslinien entlang von mir aufgestellten Kategorien, die ich dem Theoriefeld "Multikulturalismus-Feminismus" entnommen habe. Die Kategorien lauten: "Autonomie", "Unterdrückung", "Gleichheit", "Sexualisierung" und "Das Kopftuch als politisches Symbol", durch die deutlich wird, warum der von mir untersuchte Diskurs das Kopftuchverbot an Schulen unterstützt und das Kopftuch als Symbol verurteilt

Neuer Prüfstand für zügige Torsionsbeanspruchung

Die experimentelle Untersuchung von Maschinenelementen ist einer der Schwerpunkte des Institutes für Maschinenwesen. Der umfangreiche Prüfstandspark wurde nun um einen weiteren Prüfstand für zügige Torsionsbeanspruchung ergänzt. Dieser Prüfstand ermöglicht die kontinuierliche Torsion von Prüflingen auch über große Verdrehwinkel.One of the focuses of the in stitute of mechanical engineering is the experimental study of machine elements. The large park of test plants is now extended by another test plant for fast torsional stress. This test plant allows the continuous torsion of samples for large torsion angles

The Effects Of Digital Workflow Support And Workflow Control For The Performance Of Routine Pathology

Introduction/ Background Although the scanning technology for microscopic slides has been known for more than 15 years, its practical use in daily routine is still on the very beginning. Fast and reliable scanners enabled their increasing use in teaching, but not yet in consultation and primary diagnostics. So far the scanning is not handled as a process in the pathology laboratory by most of the pathology systems, leading to an interrupted workflow with delays and additional expenses. The requirement profiles for slide scanners can only be formulated with respect to their workflow integration. Aims The effects of different degrees of workflow digitalization have been studied as to analyze the sources of possible benefits of digital pathology as well as to identify the bottlenecks and inconsistencies in the workflow control in a routine pathology laboratory. The adherence to existing IHE Technical Frameworks has been evaluated, too. Methods Performance statistics of routine pathology were evaluated in different phases of digital workflow control over more than 10 years in a medium-sized institute of pathology. Three phases were defined: • Uncontrolled, but digitally supported workflow with digital dictation, digital macrophotography, digital microphotograpy at few pathology Workstations, and a “classic” pathology software system; • Digital workflow control including digital dictation and digital photography; • In a pilot study at the end of the evaluation period the additional benefits of slide scanning were estimated. Results In the period between 2006 and 2015 a decrease of turnaround-time of roughly 40% was seen. Alone the effects of a (sub)total digital workflow control contributed about half of that effect. The implementation of slide-scanning did not add further acceleration so far, but enabled some additional functionality for improving quantitative reporting. This was achieved without an explicit commitment of the pathology software to standards in workflow control and with still leaving a few laboratory processes out of the control. Milestones and key elements of workflow management are reported in detail.   Conclusion: All processes both in the laboratory and in the diagnostics have to be checked (and changed, if necessary) for being fit in a streamlined pathology workflow. The implementation of scanners into the routine diagnostics will enforce those essential developments leading to increased productivity and quality.

Pacific offshore record of plinian arc volcanism in Central America: 3. Application to forearc geology

[1] Sediment gravity cores collected on the Pacific slope and incoming plate offshore Central America reach up to 400 ka back in time and contain numerous ash layers from plinian eruptions at the Central American Volcanic Arc. The compositionally distinct widespread ash layers form a framework of marker horizons that allow us to stratigraphically correlate the sediment successions along and across the Middle America Trench. Moreover, ash layers correlated with 26 known eruptions on land provide absolute time lines through these successions. Having demonstrated the correlations in part 1, we here investigate implications for submarine sedimentary processes. Average accumulation rates of pelagic sediment packages constrained by bracketing tephras of known age range from ∼1–6 cm/ka on the incoming plate to 30–40 cm/ka on the continental slope. There are time intervals in which the apparent pelagic sedimentation rates significantly vary laterally both on the forearc and on the incoming plate where steady conditions are usually expected. A period of unsteadiness at 17–25 ka on the forearc coincides with a period of intense erosion on land probably triggered by tectonic processes. Unsteady conditions on the incoming plate are attributed to bend faulting across the outer rise triggering erosion and resedimentation. Extremely low apparent sedimentation rates at time intervals >50–80 ka suggest stronger tectonic activity than during younger times and indicate bend faulting is unsteady on a longer timescale. Submarine landslides are often associated with ash layers forming structurally weak zones used for detachment. Ash beds constrain ages of >60 ka, ∼19 ka, and <6 ka for three landslides offshore Nicaragua. Phases of intense fluid venting at mud mounds produce typical sediments around the mound that become covered by normal pelagic sediment during phases of weak or no activity. Using intercalated ash layers, we determine for the first time the durations (several hundred to 9000 years) of highly active periods in the multistage growth history of mud mounds offshore Central America, which is essential to understand general mud-mound dynamics

Nearly diffraction limited FTIR mapping using an ultrastable broadband femtosecond laser tunable from 1.33 to 8 µm

Micro-Fourier-transform infrared (FTIR) spectroscopy is a widespread technique that enables broadband measurements of infrared active molecular vibrations at high sensitivity. SiC globars are often applied as light sources in tabletop systems, typically covering a spectral range from about 1 to 20 µm (10 000 - 500 cm−1) in FTIR spectrometers. However, measuring sample areas below 40x40 µm2 requires very long integration times due to their inherently low brilliance. This hampers the detection of ultrasmall samples, such as minute amounts of molecules or single nanoparticles. In this publication we extend the current limits of FTIR spectroscopy in terms of measurable sample areas, detection limit and speed by utilizing a broadband, tabletop laser system with MHz repetition rate and femtosecond pulse duration that covers the spectral region between 1250 - 7520 cm−1 (1.33 - 8 µm). We demonstrate mapping of a 150x150 µm2 sample of 100 nm thick molecule layers at 1430 cm−1 (7 µm) with 10x10 µm2 spatial resolution and a scan speed of 3.5 µm/sec. Compared to a similar globar measurement an order of magnitude lower noise is achieved, due to an excellent long-term wavelength and power stability, as well as an orders of magnitude higher brilliance

Rainfall threshold for initiating effective stress decrease and failure in weathered tephra slopes

Rainfall is one of the most important triggers of slope failure. Weathered pyroclastic (tephra) deposits are especially vulnerable to slope failure because they commonly form slopes of high porosity and high clay content. Empirically derived thresholds for the triggering of landslides are commonly based on rainfall conditions and have been widely applied in volcanic soils. However, so far only few researchers utilized pore water pressure in the slope as additional variable for the threshold calibration. Here, we derived a new rainfall threshold for initiating the decrease in effective stress in the slope by analyzing a long-term record of rainfall and piezometer data from a slide-prone coastal area in northern New Zealand that consists of clayey, halloysitic tephra deposits. The level of effective stress decrease increased with rainfall intensity and duration. We observed highest effective stress decrease of up to 36% during rainfall events that triggered landslides in our study area. The effective stress threshold exhibits a satisfactory predictive capability. The probability of correctly predicting a decrease in effective stress is 53%. The effective stress threshold contributes towards the implementation of the decrease in effective stress into rainfall thresholds for the occurrence of landslides

A new attraction-detachment model for explaining flow sliding in clay-rich tephras

Altered pyroclastic (tephra) deposits are highly susceptible to landsliding, leading to fatalities and property damage every year. Halloysite, a low-activity clay mineral, is commonly associated with landslide-prone layers within altered tephra successions, especially in deposits with high sensitivity, which describes the post-failure strength loss. However, the precise role of halloysite in the development of sensitivity, and thus in sudden and unpredictable landsliding, is unknown. Here we show that an abundance of mushroom cap–shaped (MCS) spheroidal halloysite governs the development of sensitivity, and hence proneness to landsliding, in altered rhyolitic tephras, North Island, New Zealand. We found that a highly sensitive layer, which was involved in a flow slide, has a remarkably high content of aggregated MCS spheroids with substantial openings on one side. We suggest that short-range electrostatic and van der Waals interactions enabled the MCS spheroids to form interconnected aggregates by attraction between the edges of numerous paired silanol and aluminol sheets that are exposed in the openings and the convex silanol faces on the exterior surfaces of adjacent MCS spheroids. If these weak attractions are overcome during slope failure, multiple, weakly attracted MCS spheroids can be separated from one another, and the prevailing repulsion between exterior MCS surfaces results in a low remolded shear strength, a high sensitivity, and a high propensity for flow sliding. The evidence indicates that the attraction-detachment model explains the high sensitivity and contributes to an improved understanding of the mechanisms of flow sliding in sensitive, altered tephras rich in spheroidal halloysite