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Die Kraft des gemeinsamen Handelns: Untersuchung von Kooperationsstrategien zwischen dem Non-Profit- und dem For-Profit-Sektor für wirksames Engagement
No full textPathomechanismen der membranösen Glomerulonephritis bei PLA2R- und THSD7A-Antikörper negativen Patienten
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Organizing with Time: Temporal Perspectives on Organizational Change, Coordination, and Sustainability
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Untersuchung angeregter Zustände photoaktiver Übergangsmetallkomplexe mittels weicher Röntgenspektroskopie
No full textThis research uses soft X-ray spectroscopy and computational chemistry to investigate transition metal complexes’ electronic structure and photophysics. Specifically, the excited states in ruthenium ([Ru(bpy)2(dppp2)]2+), chromium (Cr(acac)3), and
cobalt (Cobalamin) were studied.
Chapter 1 provides a general introduction to the research, while Chapter 2 details the experimental and theoretical methods used in this thesis.
Chapter 3 investigates the electronic structure of the [Ru(bpy)2(dppp2)]2+ complex using time-dependent density functional theory (TDDFT), focusing on its two low-lying triplet 3MLCT excited states. The spectral features observed in the experiment were reproduced computationally, and the origin of each feature was found using difference density distributions. The results showed that the first spectral features in the excited state correspond to a state with an electron transfer from the metal to a single ligand.
Chapter 4 introduces an innovative configuration for conducting femtosecond time-resolved soft X-ray absorption spectroscopy (XAS) in solution. The approach utilizes a beam-splitting off-axis zone plate (BOZ) and is denoted BOZ-XAS. A key achievement of this thesis is the presentation of the analysis and interpretation of the first results of the liquid jet implementation of the BOZ-XAS method. The successful implementation of the setup was confirmed through its application to the ultrafast photoinduced spin crossover in [Fe(bpy)3]2+. Next, the effectiveness of the BOZ-XAS method was demonstrated by measuring time-resolved XAS at the Co L-edge in a 7 mM solution of cyanocobalamin, highlighting its sensitivity and efficiency.
The ground state of cyanocobalamin is low-spin Co(III) with a fully occupied t2g set. Excitation causes an electron to move to the π∗ orbital, forming the initial excited state. Subsequent relaxation processes can lead to the formation of the LMCT state. However, the similarities observed at 200 fs and 1 ps might suggest either relaxation processes occurring at the S1 potential energy level or the involvement of two electronic states with comparable spectral signatures. This result points to the need for further investigation into the relaxation mechanisms and electronic states.
In Chapter 5, picosecond Cr L-edge X-ray absorption spectroscopy was employed to investigate the electronic dynamics of Cr(acac)3, focusing on metal-centered (MC) spin-flip excited states initiated by LMCT. Experimental and theoretical integration elucidated the multiplet structure at the Cr L3-edge, revealing insights into transient electronic structure and photochemical properties. The analysis highlights significant spectral differences between ground and excited states. The analysis of spin state contributions shows that the quartet nature in the ground state spectrum shifts to a doublet character in the valence excited state. This study underscores the utility of picosecond Cr L-edge XAS for understanding transition metal complex dynamics, with implications for advanced applications like molecular sensing and photocatalysis.
Finally, Chapter 6 investigates the electronic structures of cyanocobalamin (CNCbl) and methylcobalamin (MeCbl) as thin film samples using resonant inelastic X-ray scattering (RIXS) and X-ray absorption spectroscopy complemented by CASSCF-NEVPT2 calculations. The static 2p3d RIXS spectra at the Co L3- edge were analyzed to study d-d excitations, revealing the 3T1g first electronic excitation for both complexes. Although there were difficulties due to the thin film damage, the computational analysis successfully pinpointed the initial spectral feature associated with the triplet transition and the subsequent feature linked to
the singlet transitions
Role of immunomodulatory Yersinia outer proteins during primary human macrophage infection
No full textInvestigation of antiviral antibodies against conformational epitopes of JCPyV-VP1 and large T antigen using a microarray assay
No full textDie progressive multifokale Leukenzephalopathie (PML) wurde erstmals als Entmarkungserkrankung im Jahr 1958 als Komplikation chronisch lymphatischer Leukämie, Tuberkulose und der Hodgkin’schen Erkrankung beschrieben. 1971 wurde das Virus aus dem Gehirn eines Patienten isoliert und nach diesem als John-Cunningham-(Polyoma-)Virus (JCPyV) bezeichnet. Nach Einführung von Natalizumab (NAT, Tysabri®) zur Behandlung der schubförmig remittierenden Multiplen Sklerose (RRMS) wurde 2005 deutlich, dass der JCV-Antikörperstatus, eine vorbestehende Immusuppresion und die Zahl der verabreichten NAT-Infusionen mit dem Erkrankungsrisiko der PML zusammenhängt. Klinisch fanden sich am häufigsten kognitive Ausfälle, Verhaltensänderungen, epileptische Anfälle sowie motorische und sensible Störungen.
Zur Identifikation von Peptiden bzw. von Mustern der Immunantwort auf JCPyV bei MS-Patienten wurden mithilfe eines Microarray-Assays paarweise die Antikörpertiter der experimentellen Gruppe (EG, PML unter NAT-Therapie) mit vier Kontrollgruppen (CG) – JCV-seropositiv bzw. -seronegativ, Behandlung mit NAT oder anderer Immusuppresion – untersucht. Es wurden 94 konformationelle Peptide aus dem VP1 bzw. LT-Ag des JCPyV und vier Kontrollpeptide (EBNA-1, MBP1 und 2 sowie MOG) eingesetzt.
Es ließen sich sieben Peptide aus dem VP1 identifizieren, die signifikant häufiger und mit höheren Antikörpertitern bei PML-Patienten gefunden werden.
Damit wird es möglich konformationelle Epitope für eine prophylaktische Impfung gegen JCPyV zu evaluieren. Es eröffnet Wege monoklonale Antikörper oder kleine Moleküle zur Untersuchung der Scharnierfunktion, des Viruszusammenbaus und der Vermehrung zu analysieren. Bisher besteht die einzig erfolgreiche Therapie in der erfolgreichen Therapie der Grunderkrankung. Weiterführende Untersuchungen an einem größeren Patientenkollektiv sind erforderlich, um diese Hypothese zu falsifizieren oder zu bestätigen.Progressive multifocal leukoencephalophathy (PML) was first described as a demyelinating disease in 1958 as a complication of chronic lymphocytic leukemia, tuberculosis and Hodgkin’s disease. In 1971 a polyomavirus was isolated from the brain of the patient John Cunningham. It was serologically identified as closely related to Simian-Vacuolating-Virus 40 (SV-40) and named John-Cunningham-(Polyoma-)Virus (JCPyV). The risk of MS-patients to develop PML while taking Natalizumab (NAT, Tysabri®) was first identified in 2005. In the following years factors such as the JCV-antibodystatus, previous immunosuppressive therapy and number of infusions received were identified as risk factors. The most common symptoms are cognitive deficits, behavioral, sensory and motor disturbances and seizures.
The aim of this design is to identify a pattern of immune responses against epitopes that will allow early detection of patients who either have or are developing PML. Therefore a microarray assay was developed to analyze the reactivity of sera from four control groups (CG) and a group of NAT-PML patients (EG). Sera from EG were each compared in pairs with JCV-seropositive or JCV-seronegative patients treated either with NAT or with other immunosuppressive treatment. All samples were analyzed by endpoint dilution with conformational peptides. 94 viral peptides were derived from VP1- or the LT-Ag-gene of JCPyV and 4 control peptides (EBNA-1, MBP1 and 2 and also MOG).
Seven peptides from VP1, one from LT-Ag and two controls were identified with a statistically significant higher frequency and higher antibody titers in PML patients.
It could pave the way to prophylactic vaccination or development of specific monoclonal antibodies or small molecules to analyze the the role and function of the hinge in virus assembly and replication. This is highly relevant because to date, apart from successful treatment of the underlying disease, there is no effective, approved therapy for PML. Further studies are needed in a larger patient population to explore this hypothesis