Nichtwässrige Kapillarelektrophorese zur Analytik von Peptiden

In der vorliegenden Arbeit wurden verschiedene Peptide mit Hilfe der nichtwässrigen Kapillarelektrophorese (NACE) analysiert. Es wurden sowohl grundsätzliche, trennmethodische Fragestellungen bearbeitet als auch praktische Anwendungen für die NACE-Analytik von Peptiden entwickelt. Im ersten Teil der vorliegenden Arbeit wurde der Einfluss nichtwässriger Lösungsmittel auf das Dissoziationsverhalten und die Sekundärstruktur von Peptiden untersucht, welche entscheidend das Migrationsverhalten von Peptiden in der CE bestimmen. Im zweiten Teil der Arbeit wurden zwei Anwendungsbeispiele für den Einsatz der NACE zur Analyse von Peptiden entwickelt, wobei die Kopplung mit der massenspektrometrischen und der elektrochemischen Detektion im Vordergrund stand

Promoting Persistent Superionic Conductivity in Sodium Monocarba-closo-dodecaborate NaCB11H12 via Confinement within Nanoporous Silica

Superionic phases of bulk anhydrous salts based on large cluster-like polyhedral (carba)borate anions are generally stable only well above room temperature, rendering them unsuitable as solid-state electrolytes in energy-storage devices that typically operate at close to room temperature. To unlock their technological potential, strategies are needed to stabilize these superionic properties down to subambient temperatures. One such strategy involves altering the bulk properties by confinement within nanoporous insulators. In the current study, the unique structural and ion dynamical properties of an exemplary salt, NaCB11H12, nanodispersed within porous, high-surface-area silica via salt-solution infiltration were studied by differential scanning calorimetry, X-ray powder diffraction, neutron vibrational spectroscopy, nuclear magnetic resonance, quasielastic neutron scattering, and impedance spectroscopy. Combined results hint at the formation of a nanoconfined phase that is reminiscent of the high-temperature superionic phase of bulk NaCB11H12, with dynamically disordered CB11H12-anions exhibiting liquid-like reorientational mobilities. However, in contrast to this high-temperature bulk phase, the nanoconfined NaCB11H12 phase with rotationally fluid anions persists down to cryogenic temperatures. Moreover, the high anion mobilities promoted fast-cation diffusion, yielding Na+ superionic conductivities of similar to 0.3 mS/cm at room temperature, with higher values likely attainable via future optimization. It is expected that this successful strategy for conductivity enhancement could be applied as well to other related polyhedral (carba)borate-based salts. Thus, these results present a new route to effectively utilize these types of superionic salts as solid-state electrolytes in future battery applications

Sucrose diffusion in aqueous solution.

The diffusion of sugar in aqueous solution is important both in nature and in technological applications, yet measurements of diffusion coefficients at low water content are scarce. We report directly measured sucrose diffusion coefficients in aqueous solution. Our technique utilises a Raman isotope tracer method to monitor the diffusion of non-deuterated and deuterated sucrose across a boundary between the two aqueous solutions. At a water activity of 0.4 (equivalent to 90 wt% sucrose) at room temperature, the diffusion coefficient of sucrose was determined to be approximately four orders of magnitude smaller than that of water in the same material. Using literature viscosity data, we show that, although inappropriate for the prediction of water diffusion, the Stokes-Einstein equation works well for predicting sucrose diffusion under the conditions studied. As well as providing information of importance to the fundamental understanding of diffusion in binary solutions, these data have technological, pharmaceutical and medical implications, for example in cryopreservation. Moreover, in the atmosphere, slow organic diffusion may have important implications for aerosol growth, chemistry and evaporation, where processes may be limited by the inability of a molecule to diffuse between the bulk and the surface of a particle

Caliphate and the contemporary attempt at its reactivation

Od śmierci Muhammada umma borykała się z problemem wyłonienia powszechnie akceptowanego przywódcy. Spór ten musiał jednak zakończyć się jakimś konsensusem. Pierwszym rozwiązaniem był okres tzw. kalifów wybieralnych, przez większość akceptowanych ze względu na ich bliskość czasową z Prorokiem i świadectwo życia. Późniejszą praktyką stał się dziedziczny kalifat Umajjadów, a następnie Abbasydów. Instytucja ta zakończyła się wraz z upadkiem Bagdadu w 1258 roku. Wielokrotnie podejmowano bezowocne próby reaktywacji kalifatu, który w ostateczności został zniesiony w 1924 roku. Dziś wraca się do tej idei. Ogłoszony w 2014 roku kalifem Abu Bakr al-Baghdadi, przywódca Państwa Islamskiego (ISIS), jest dosyć zagadkową postacią i jednym z najbardziej niebezpiecznych przywódców terrorystycznych na świecie. W kontekście jego osoby pojawiają się pytania dotyczące kryteriów i ważności dokonania tego wyboru, jak również zasadności innych muzułmańskich form sprawowania władzy.After the death of Muhammad, the ummah had a problem how to select one universally accepted leader. For some time, they were elected by the majority of Muslims for their worthy conduct and friendship with the Prophet. These were the elected caliphs. Later, the caliphate became hereditary, hold first by the Umayyads, and then the Abbasids. The caliphate ended with the fall of Baghdad in 1258. There have been many fruitless efforts to reestablish caliphate. It was ffinally abolished in 1924. Today, some reanimate the idea of caliphate. Abu Bakr al-Baghdadi, declared caliph in 2014, head of the Islamic State (ISIS), is quite a puzzling person, one of the most dangerous global terrorist leaders. There are some questions concerning the criteria and validity of his election and legitimacy of other Muslim forms of authority

Nonaqueous versus aqueous capillary electrophoresis of alpha-helical polypeptides: Effect of secondary structure on separation selectivity

The CE separation of alpha-helical polypeptides composed of 14-31 amino acid residues has been investigated using aqueous and nonaqueous BGEs. The running buffers were optimized with respect to pH. Generally, higher separation selectivities were observed in nonaqueous electrolytes. This may be explained by a change in the secondary structure when changing from water to organic solvents. Circular dichroism spectra revealed a significant increase in helical structures in methanol-based buffers compared to aqueous buffers. This change in secondary structure of the polypeptides contributed primarily to the different separation selectivity observed in aqueous CE and NACE. For small oligopeptides of two to five amino acid residues no significant effect of the solvent was observed in some cases while in other cases a reversal of the migration order occurred when changing from aqueous to nonaqueous buffers. As these peptides cannot adopt secondary structures the effect may be attributed to a shift of the pKa values in organic solvents compared to water

Non-linear charge transport in polythiophene under high AC field

Complex impedance and conductivity were measured for regioregular poly(3hexylthiophene) (P3HT) at alternating current (AC) voltages using a waveform technique. The waveforms were Fourier transformed from time domain to frequency domain and analyzed at fundamental and higher order harmonic frequencies. It was found that the impedance of the semi-conducting P3HT decreases with increasing electric field strength. The non-linear charge transport is dominated by a third harmonic response that originates from extended polarizability of π-type electronic states. The third order non-linear conductivity can be used to quantify the effect of an electric field on the conduction mechanism and to correlate the intrinsic charge carriers mobility with molecular structure