Structural and vibrational study of 8-hydroxyquinoline-2-carboxaldehyde isonicotinoyl hydrazone: a potential metal-protein attenuating compound (MPAC) for the treatment of Alzheimer's disease

A comprehensive structural and vibrational study of the potential metal-protein attenuating compound 8-hydroxyquinoline-2-carboxaldehyde isonicotinoyl hydrazone is reported. X-ray diffraction data, as well as FT-IR and Raman frequencies, were compared with the respective theoretical values obtained from DFT calculations. Theory agrees well with experiment. In this context, an attempt of total assignment concerning the FT-IR and Raman spectra of the title compound was performed, shedding new light on previous partial assignments published elsewhere.

Diffusivity and enzymatic activity control the exchange of carbonyl sulfide (COS) between soils and the atmosphere

Carbonylsulfid (COS) ist eines der stabilsten reduzierten schwefelhaltigen Spurengase in der Atmosphäre. In der gut durchmischten Troposphäre bewegt sich seine Konzentration um 500 ppt. COS spielt eine wichtige Rolle in der Produktion von stratosphärischem Aerosol und im Ozon Zyklus. Dieses Spurengas hat eine Vielfalt an natürlichen und anthropogenen Quellen, denen gleichstarke Senken, darunter die dominanten wie Vegetation und Boden, gegenüber stehen. Die Stärke der Senken ist trotz langjähriger Forschungen immer noch Gegenstand der Diskussionen. Daher ist es wichtig die kontrollierenden Parameter zu charakterisieren. Alle Austauschmessungen vor 1990 vermuteten Böden als Quelle von COS, was aber durch Castro and Galloway (1991) klar widerlegt wurde. Heute werden Böden in Ergänzung zur Vegetation grundsätzlich als Senke betrachtet. Vor diesem Hintergrund wurden Bodenproben auf den Austausch von Carbonylsulfid mit der Atmosphäre unter verschiedenen Umgebungsbedingungen untersucht. Drei Ackerböden aus Deutschland, China und Finnland und zwei Waldböden aus Sibirien und Surinam konnten parametrisiert werden in Relation zur atmosphärischen Umgebungskonzentration, Temperatur und Bodenfeuchte (WC). Neben Umgebungskonzentration und Bodenfeuchte, scheinen Bodenstruktur und enzymatische Aktivität die Richtung und Größe des Austauschflusses zu kontrollieren. Die übereinstimmenden Optima für boreale Böden in Relation zum wassergefüllten Porenvolumen des Bodens (WFPS) und die Linearität zwischen Depositionsgeschwindigkeit (Vd) und Bulk density lassen auf eine Dominanz der Abhängigkeit der COS-Aufnahme von der durch WFPS bestimmten Diffusionsfähigkeit schließen. WFPS ist abhängig von WC, Bodenstruktur und Bodenporosität. In Ergänzung zu diesen eher physikalischen Parametern konnte die Carboanhydrase (CA) als kontrollierendes Enzym in Böden identifiziert werden. Erste Versuche zur direkten Bestimmung der CA in den untersuchten Böden erlaubten eine erste, aber noch sehr ungenaue Abschätzung der Enzymaktivität.

Magnetic tunneling junctions with the Heusler compound Co 2 Cr 0.6 Fe 0.4 Al

Materialen mit sehr hoher Spinpolarisation werden für Anwendungen im Bereich der Spin-Elektronik benötigt. Deshalb werden große Forschungsanstrengungen zur Untersuchung der Eigenschaften von Verbindungen mit potentiell halbmetallischem Charakter, d. h.mit 100% Spinpolarisation, unternommen. In halbmetallischen Verbindungen, erwartet man eine Lücke in der Zustandsdichte an der Fermi Energie für Ladungsträger einer Spinrichtung, wahrend die Ladungsträger mit der anderen Spinrichtung sich metallisch verhalten. Eine Konsequenz davon ist, dass ein Strom, der durch solche Verbindung fließt, voll spinpolarisiert ist. Die hohe Curie-Temperatur Tc (800 K) und der theoretisch vorhergesagte halbmetallische Charakter machen Co2Cr0.6Fe0.4Al (CCFA) zu einem guten Kandidaten für Spintronik-Anwendungen wie magnetische Tunnelkontakte (MTJs = Magnetic Tunneling Junctions). In dieser Arbeit werden die Ergebnisse der Untersuchung der elektronischen und strukturellen Eigenschaften von dünnen CCFA Schichten dargestellt. Diese Schichten wurden in MTJs integriert und der Tunnel-Magnetowiderstands-Effekt untersucht. Hauptziele waren die Messung der Spinpolarisation und Untersuchungen der elektronischen Struktur von CCFA. Der Einfluss verschiedener Depositionsparameter auf die Eigenschaften der Schichten, speziell auf der Oberflächenordnung und damit letztlich auf den Tunnel-Magnetowiderstand (TMR), wurde bestimmt. Epitaktische d¨unne CCFA Schichten mit zwei verschiedenen Wachstumsrichtungen wurden auf verschiedene Substrate und Pufferschichten deponiert. Ein Temperverfahren wurde eingesetzt um die strukturelle Eigenschaften der dünnen Schichten zu verbessern. Für die MTJs wurde Al2O3 als Barrierenmaterial verwendet und Co als Gegenelektrode gewählt. Die Mehrschicht-Systeme wurden in Mesa-Geometrie mit lithographischen Methoden strukturiert. Eine maximal Jullière Spinpolarisation von 54% wurde an Tunnelkontakte mit epitaktischen CCFA Schichten gemessen. Ein starker Einfluss der Tempernbedingungen auf dem TMR wurde festgestellt. Eine Erhörung des TMR wurde mit einer Verbesserung der Oberflächenordung der CCFA Schichten korreliert. Spektroskopische Messungen wurden an den MTJs durchgeführt. Diesen Messungen liefern Hinweise auf inelastische Elektron-Magnon und Elektron-Phonon Stossprozesse an den Grenzflächen. Einige der beobachteten Strukturen konnten mit der berechneten elektronischen Struktur von CCFA korreliert worden.

Unconventional superconductivity of the heavy fermion compound UNi 2 Al 3

The heavy fermion compound UNi2Al3 exhibits the coexistence of superconductivity and magnetic order at low temperatures, stimulating speculations about possible exotic Cooper-pairing interaction in this superconductor. However, the preparation of good quality bulk single crystals of UNi2Al3 has proven to be a non-trivial task due to metallurgical problems, which result in the formation of an UAl2 impurity phase and hence a strongly reduced sample purity. The present work concentrates on the preparation, characterization and electronic properties investigation of UNi2Al3 single crystalline thin film samples. The preparation of thin films was accomplished in a molecular beam epitaxy (MBE) system. (100)-oriented epitaxial thin films of UNi2Al3 were grown on single crystalline YAlO3 substrates cut in (010)- or (112)-direction. The high crystallographic quality of the samples was proved by several characterisation methods, such as X-ray analysis, RHEED and TEM. To study the magnetic structure of epitaxial thin films resonant magnetic x-ray scattering was employed. The magnetic order of thin the film samples, the formation of magnetic domains with different moment directions, and the magnetic correlation length were discussed. The electronic properties of the UNi2Al3 thin films in the normal and superconducting states were investigated by means of transport measurements. A pronounced anisotropy of the temperature dependent resistivity ρ(T) was observed. Moreover, it was found that the temperature of the resistive superconducting transition depends on the current direction, providing evidence for multiband superconductivity in UNi2Al3. The initial slope of the upper critical field H′c2(T) of the thin film samples suggests an unconventional spin-singlet superconducting state, as opposed to bulk single crystal data. To probe the superconducting gap of UNi2Al3 directly by means of tunnelling spectroscopy many planar junctions of different design employing different techniques were prepared. Despite the tunneling regime of the junctions, no features of the superconducting density of state of UNi2Al3 were ever observed. It is assumed that the absence of UNi2Al3 gap features in the tunneling spectra was caused by imperfections of the tunnelling contacts. The superconductivity of UNi2Al3 was probably suppressed just in a degraded surface layer, resulting in tunneling into non superconducting UNi2Al3. However, alternative explanations such as intrinsic pair breaking effects at the interface to the barrier are also possible.

Oxygen-containing polycyclic aromatic hydrocarbons (OPAHs) and their parent-PAHs in soil

In spite of the higher toxicity of oxygen-containing polycyclic aromatic hydrocarbons (OPAHs) than of their parent-PAHs, there are only a few studies of the concentrations, composition pattern, sources and fate of OPAHs in soil, the presumably major environmental sink of OPAHs. This is related to the fact that there are only few available methods to measure OPAHs together with PAHs in soil. rnThe objectives of my thesis were to (i) develop a GC/MS-based method to measure OPAHs and their parent-PAHs in soils of different properties and pollution levels, (ii) apply the method to soils from Uzbekistan and Slovakia and (iii) investigate into the fate of OPAHs, particularly their vertical transport in soilrnI optimized and fully evaluated an analytical method based on pressurized liquid extraction, silica gel column chromatographic fractionation of extracted compounds into alkyl-/parent-PAH and OPAH fractions, silylation of hydroxyl-/carboxyl-OPAHs with N,O-bis(trimethylsilyl)trifluoracetamide and GC/MS quantification of the target compounds. The method was targeted at 34 alkyl-/parent-PAHs, 7 carbonyl-OPAHs and 19 hydroxyl-/carboxyl-OPAHs. I applied the method to 11 soils from each of the Angren industrial region (which hosts a coal mine, power plant, rubber factory and gold refinery) in Uzbekistan and in the city of Bratislava, the densely populated capital of Slovakia.rnRecoveries of five carbonyl-OPAHs in spike experiments ranged between 78-97% (relative standard deviation, RSD, 5-12%), while 1,2-acenaphthenequinone and 1,4-naphtho-quinone had recoveries between 34-44%% (RSD, 19-28%). Five spiked hydroxyl-/carboxyl-OPAHs showed recoveries between 36-70% (RSD, 13-46%), while others showed recoveries <10% or were completely lost. With the optimized method, I determined, on average, 103% of the alkyl-/parent-PAH concentrations in a certified reference material.rnThe ∑OPAHs concentrations in surface soil ranged 62-2692 ng g-1 and those of ∑alkyl-/parent-PAHs was 842-244870 ng g-1. The carbonyl-OPAHs had higher concentrations than the hydroxyl-/carboxyl-OPAHs. The most abundant carbonyl-OPAHs were consistently 9-fluorenone (9-FLO), 9,10-anthraquinone (9,10-ANQ), 1-indanone (1-INDA) and benzo[a]anthracene-7,12-dione (7,12-B(A)A) and the most abundant hydroxyl-/carboxyl-OPAH was 2-hydroxybenzaldehyde. The concentrations of carbonyl-OPAHs were frequently higher than those of their parent-PAHs (e.g., 9-FLO/fluorene >100 near a rubber factory in Angren). The concentrations of OPAHs like those of their alkyl-/parent-PAHs were higher at locations closer to point sources and the OPAH and PAH concentrations were correlated suggesting that both compound classes originated from the same sources. Only for 1-INDA and 2-biphenylcarboxaldehyde sources other than combustion seemed to dominate. Like those of the alkyl-/parent-PAHs, OPAH concentrations were higher in topsoils than subsoils. Evidence of higher mobility of OPAHs than their parent-PAHs was provided by greater subsoil:topsoil concentration ratios of carbonyl-OPAHs (0.41-0.82) than their parent-PAHs (0.41-0.63) in Uzbekistan. This was further backed by the consistently higher contribution of more soluble 9-FLO and 1-INDA to the ∑carbonyl-OPAHs in subsoil than topsoil at the expense of 9,10-ANQ, 7,12-B(A)A and higher OPAH/parent-PAH concentration ratios in subsoil than topsoil in Bratislava.rnWith this thesis, I contribute a suitable method to determine a large number of OPAHs and PAHs in soil. My results demonstrate that carbonyl-OPAHs are more abundant than hydroxyl-/carboxyl-OPAHs and OPAH concentrations are frequently higher than parent-PAH concentrations. Furthermore, there are indications that OPAHs are more mobile in soil than PAHs. This calls for appropriate legal regulation of OPAH concentrations in soil.

Developments for transactinide chemistry experiments behind the gas-filled separator TASCA

Topic of this thesis is the development of experiments behind the gas-filled separator TASCA(TransActinide Separator and Chemistry Apparatus) to study the chemical properties of the transactinide elements.rnIn the first part of the thesis, the electrodepositions of short-lived isotopes of ruthenium and osmium on gold electrodes were studied as model experiments for hassium. From literature it is known that the deposition potential of single atoms differs significantly from the potential predicted by the Nernst equation. This shift of the potential depends on the adsorption enthalpy of therndeposited element on the electrode material. If the adsorption on the electrode-material is favoured over the adsorption on a surface made of the same element as the deposited atom, the electrode potential is shifted to higher potentials. This phenomenon is called underpotential deposition.rnPossibilities to automatize an electro chemistry experiment behind the gas-filled separator were explored for later studies with transactinide elements.rnThe second part of this thesis is about the in-situ synthesis of transition-metal-carbonyl complexes with nuclear reaction products. Fission products of uranium-235 and californium-249 were produced at the TRIGA Mainz reactor and thermalized in a carbon-monoxide containing atmosphere. The formed volatile metal-carbonyl complexes could be transported in a gas-stream.rnFurthermore, short-lived isotopes of tungsten, rhenium, osmium, and iridium were synthesised at the linear accelerator UNILAC at GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt. The recoiling fusion products were separated from the primary beam and the transfer products in the gas-filled separator TASCA. The fusion products were stopped in the focal plane of TASCA in a recoil transfer chamber. This chamber contained a carbon-monoxide – helium gas mixture. The formed metal-carbonyl complexes could be transported in a gas stream to various experimental setups. All synthesised carbonyl complexes were identified by nuclear decay spectroscopy. Some complexes were studied with isothermal chromatography or thermochromatography methods. The chromatograms were compared with Monte Carlo Simulations to determine the adsorption enthalpyrnon silicon dioxide and on gold. These simulations based on existing codes, that were modified for the different geometries of the chromatography channels. All observed adsorption enthalpies (on silcon oxide as well as on gold) are typical for physisorption. Additionally, the thermalstability of some of the carbonyl complexes was studied. This showed that at temperatures above 200 °C therncomplexes start to decompose.rnIt was demonstrated that carbonyl-complex chemistry is a suitable method to study rutherfordium, dubnium, seaborgium, bohrium, hassium, and meitnerium. Until now, only very simple, thermally stable compounds have been synthesized in the gas-phase chemistry of the transactindes. With the synthesis of transactinide-carbonyl complexes a new compound class would be discovered. Transactinide chemistry would reach the border between inorganic and metallorganic chemistry.rnFurthermore, the in-situ synthesised carbonyl complexes would allow nuclear spectroscopy studies under low background conditions making use of chemically prepared samples.

Homo- and Heterometal Carbonyl Nanoclusters

In this thesis, the syntheses and the characterizations of several new bimetallic carbonyl clusters have been outlined. X-ray crystallography is a key technique in order to elucidate their structures which can be related to their chemical and physical properties. In particular, electrochemical studies are very useful in order to understand how the physical properties of metal aggregates change with increasing size and when the molecular behavior fades into bulk behavior. Moreover, the incipient metallization of the cluster has be assessed (not measured) via UV-vis analyses even if this technique revealed to be not very useful in order to distinguish the different species present in solution. Overall, this work demonstrates that molecular nanoclusters are ideal models in order to better understand the structures and properties of ultrasmall metal nanoparticles.

Der Einfluss des Angiotensin-II-Typ-2-Agonisten Compound 21 auf den neuronalen Schaden bei der Maus nach traumatischer Hirnläsion mittels Controlled Cortical Impact

Die Beeinflussung des sekundären Hirnschadens nach SHT ist Hauptansatzpunkt der klinischen Therapie. Gleichzeitig sind die zugrunde liegenden Mechanismen zum Großteil unklar und Gegenstand aktueller Forschung. In verschiedenen Studien scheint sich das Renin-Angiotensin-Aldosteron-System als Teil der Pathophysiologie bei der Entstehung des sekundären Hirnschadens und der neuronalen Inflammation nach SHT herauszukristallisieren. Der Fokus richtet sich mitunter auf den AT2- Rezeptor, dessen protektive Wirkung in verschiedensten Ischämiemodellen und Geweben gezeigt werden konnte.rnIn der vorliegenden Promotionsarbeit wurde erstmalig die Wirkung einer AT2- Stimulation auf histologische, inflammatorische und neuromotorische Parameter nach CCI untersucht. Eine neuroprotektive Wirkung der AT2-Stimulation konnte dabei nicht nachgewiesen werden. Es kam weder zu einer Beeinflussung histologischer noch neuromotorischer Parameter, allerdings scheint der AT2-Agonist C21 bei einer Dosierung von 0,03 mg/kg KG zu einer Stimulation der inflammatorischen Reaktion zu führen.

Noncollinear magnetism in Mn2RhSn Heusler compound

Heusler compounds is a large class of materials, which exhibits diverse fundamental phenomena, together with the possibility of their specific tailoring for various engineering demands. Present work discusses the magnetic noncollinearity in the family of noncentrosymmetric ferrimagnetic Mn2-based Heusler compounds. Based on the obtained experimental and theoretical results, Mn2YZ Heusler family is suspected to provide promising candidates for the formation of the skyrmion lattice. The work is focused on Mn2RhSn bulk polycrystalline sample, which serves as a prototype. It crystallizes in the tetragonal noncentrosymmetric structure (No. 119, I-4m2), which enables the anisotropic Dzyaloshinskii-Moriya (DM) exchange coupling. Additional short-range modulation, induced by the competing nearest and next-nearest interplanes Heisenberg exchange, is suppressed above the 80 K. This allows to develop the long-range modulations in the ideal ferrimagnetic structure within the ab crystallographic planes, and thus, favors to the occurrence of the skyrmion lattice within the temperature range of (80 ≤ T ≤ 270) K. The studies of Mn2RhSn were expandedrnto the broad composition range and continued on thin film samples.

Synthesis and functionalization of a lactam-pyrazole molecular scaffold as a promising anticancer compound

The importance of pyrazole and lactam-based molecules in medical and pharmaceutical fields is underlined by the multitude of active ingredients on trade, such as Sildenafil or Apixaban, by Pfizer. In this work, a synthesis of an organic molecule with promising anticancer activity has been developed. This molecular scaffold is characterized by a δ-lactam-fused pyrazolic core, with a well-known biological activity and amenable of further functionalization. The synthetic strategy adopted for the obtainment of the core was based on a 1,3-dipolar cycloaddition of a nitrilimine with an α,β-unsaturated δ-lactam. Secondly, in order to give the final compound an elevated pharmacological activity, a functionalization with a double “side chain”, namely molecular fragment able to improve the interaction with particular biological receptors, was achieved. The target compound was thus obtained, with a highly convergent synthesis, and will be tested for antiproliferative activities towards different cellular lines.

Sintesi e caratterizzazione di nuovi cluster carbonilici Rh-Sb e Rh-Ge

The topic of my thesis was focused on the synthesis of heteroatomic Rh clusters stabilized by carbonyl ligands. I studied the reactivity of [Rh7(CO)16]3- with different Sb3+ and Ge4+ salts, and tried to synthesize new species by changing the reaction conditions. Indeed, in order to obtain new Rh-Sb and Rh-Ge clusters, I employed different stoichiometric ratios, solvents and atmospheres (N2 or CO). As far as the Rh-Sb system is concerned, I successfully synthesized three new compounds through two different reactions, namely [Rh20Sb3(CO)36][NEt4]3, [Rh21Sb2(CO)38][NEt4]5 and [Rh12Sb(CO)24][NEt4]3. At the same time, I investigated the Rh-Ge system and succeeded in the isolation of the new cluster [Rh14Ge2(CO)30][NEt4]2, along with [Rh12SbGePh2(CO)26][NEt4]2, by treating [Rh7(CO)16]3- with both Ge4+ and Sb3+ salts. Each compound has been characterized by IR spectroscopy, ESI-MS spectrometry and single crystal X-ray diffractometry. Finally, I conduced chemical reactivity tests on some of the obtained compounds.

In vivo and in vitro effects of genistein as obesogenic/anti-obesogenic compound in the lipid metabolism of rainbow trout (Oncorhynchus mykiss)

Nowadays, soy is one of the most used ingredients in the formulation of fish feed, due to the ample market supply, lower market price, high protein concentration and favorable amino acid composition. Nevertheless, soybean meal products are rich and primary diet source of phytoestrogens, as genistein, which may have a potential negative impact on growth, hormonal regulation and lipid metabolism in fish. The principal aim of this study was to better understand in vivo and in vitro genistein’s effects on lipid metabolism of rainbow trout. In adipose tissue it was showed an unclear role of genistein on lipid metabolism in rainbow trout, and in liver an anti-obesogenic effect, with an up-regulation of autophagy-related genes LC3b (in adipose tissue) and ATG4b (in liver and adipose tissue), a down-regulation of apoptosis-related genes CASP3 (in adipose tissue) and CASP8 (in liver). An increase of VTG mRNA levels in liver was also observed. Genistein partially exerted these effects via estrogen- receptor dependent mechanism. In white muscle, genistein seemed to promote lipid turnover, up-regulating lipogenic (FAS and LXR) and lipolytic (HSL, PPARα and PPARβ) genes. It seemed that genistein could exert its lipolytic role via autophagic way (up-regulation of ATG4b and ATG12l), not through an apoptotic pathway (down-regulation of CASP3). The effects of genistein on lipid-metabolism and apoptosis-related genes in trout muscle were not dose-dependent, only on autophagy-related genes ATG4B and ATG12l. Moreover, a partial estrogenic activity of this phytoestrogen was also seen. Through in vitro analysis (MTT and ORO assay), instead, it was observed an anti-obesogenic effect of genistein on rainbow trout adipocytes, and this effect was not mediated by ERs. Both in vivo and in vitro, genistein exerted its effects in a dose-dependent manner.