Purge

This thesis statement describes the eight hanging veil-like structures and sculptures that constitute my thesis exhibition work; it further comments on the movements, philosophy, and personal sensibility that most influenced the art making: Process Art, Taoism, and my own empathetic experiences. The movement of Process Art is discussed in reference to materiality and the physicality that goes into making these pieces. The influence of the Taoist philosophy is discussed in light of the unity and balance found in the combination of dualistic materials, and their relationship to one another, in these sculptural forms. Lastly, this statement expresses how the emotional states brought about from my own empathetic experiences and interpersonal relationships have had an effect on the way I manipulate the materials and on my construction process. My intention is to invite the viewer to follow a journey through the process of making these objects. This is meant to engage the viewer to investigate the multiple fragmented constructions that are unified into one form. As this exploration occurs, tensions created from the dualistic nature of the materials used and the emotional tension that is “recorded” from the action upon those materials elicits in the viewer their own emotional response. It is through intrigue that I stimulate the viewers\u27 contemplation of their own emotional states

The Capital Market Effects of Machine-Readable Data Errors: Evidence from XBRL US Data Quality Committee Rules

Motivated by Section 5825 of the 2022 Financial Data Transparency Act, I investigate the capital market effects of XBRL errors. Using XBRL US Data Quality Committee (DQC) rule errors, the SEC’s indicator of low-quality, machine-readable data, in 10-K XBRL filings, I find no evidence of an increase in information asymmetry or a decrease in the efficiency of stock price formation for filings with an error. Additional analyses reveal the findings are driven more by a weak association between DQC rule errors and a material decrease in the precision of value-relevant accounting information and less by limited investor usage of machine-readable financial data. Overall, this study provides valuable insights given this component of financial reporting quality is under increasing regulatory scrutiny, yet I document no adverse capital market effects between filings with and without XBRL errors. This suggests that investors will not see significant capital market benefits from the regulatory focus on increasing the quality level of XBRL filings through the elimination of DQC rule errors

Raman Spectroscopy of the Sampleite Group of Minerals

Raman and infrared spectroscopy has enabled insights into the molecular structure of the sampleite group of minerals. These minerals are based upon the incorporation of either phosphate or arsenate with chloride anion into the structure and as a consequence the spectra refect the bands attributable to these anions, namely phosphate or arsenate with chloride. The sampleite vibrational spectrum reflects the spectrum of the phosphate anion and consists of ν1 at 964, ν2 at 451 cm-1, ν3 at 1016 and 1088 and ν4 at 643, 604, 591 and 557 cm-1. The lavendulan spectrum consists of ν1 at 854, ν2 at 345 cm-1, ν3 at 878 cm-1 and ν4 at 545 cm-1. The Raman spectrum of lemanskiite is different from that of lavendulan consistent with a different structure. Low wavenumber bands at 227 and 210 cm-1 may be assigned to CuCl TO/LO optic vibrations. Raman spectroscopy identified the substitution of arsenate by phosphate in zdenekite and lavendulan

Structural and Functional Studies on IroB: A Pathogen-Associated C-glycosyltransferase

Bacterial iron acquisition by the means of enterobactin (ENT) is constrained in mammalian hosts due to ENT-binding proteins such as siderocalin and serum albumin. To evade sequestration by these proteins, ENT can be modified by the C glycosyltransferase IroB, which is located in the iroA locus of Salmonella and certain extraintestinal E. coli strains such as uropathogenic E. coli CFT073. The glycosylation of ENT has been reported to be a bacterial evasion mechanism to restore the iron scavenging ability of ENT in the presence of mammalian ENT-binding proteins by the installation of a steric impediment. The C glycosyltransferase IroB catalyses the transfer of a glucose moiety to the DHB subunit of ENT under formation of a C-C bond between the anomeric C1 of the glucose moiety and the C5 of the 2,3-DHB subunit of ENT. The formation of mono-, di- and triglycosylated Ent (MGE/DGE/TGE) products where observed in vitro. The formation of a C-C bond is remarkable because of its chemical stability and resilience against enzymatic degradation. In this M.Sc. thesis, we initially identified the iroB gene product in the iroA harbouring E. coli strain Nissle 1917 on transcriptional and translational level and expressed and purified IroB recombinant. Then, we investigated the mechanism of the C-C bond formation catalysed by IroB in vitro. Based on the hypothesis that deprotonation of the catechol 2 hydroxyl renders the catechol C5 para to the 2-hydroxyl nucleophilic, the C-C bond would then be formed in a general SN2 reaction between the attacking nucleophile and the anomeric carbon of glucose, which is further facilitated by the excellent phosphate leaving group of the UDP-glucose donor. By the means of homology modelling and superposition strategies, we were able to identify the binding sites of the glycosyl donor UDP-glucose and the glycosyl acceptor ENT and to locate residues that could potentially act as base catalysts to increase the phenolate anionic character of the 2,3-DHB subunit during catalysis. We established an activity assay for IroB, separated products arising from IroB activity by reversed phase chromatography and compared so the activity of wild-type IroB and several variants. Additionally, all variants were characterized biophysically, mainly to confirm that the structural integrity was not impaired by mutations. Ultimately, our results enable us to propose a mechanism for C-glycosylation of IroB that is consistent with other glycosyltransferases found in nature

Challenges and solution approach for greenhouse gas emission inventories at fine spatial resolutions – the example of the Rhine-Neckar district

This discussion paper originated as the concluding publication of one of the pilot projects of the "Climate Action Science" research initiative at Heidelberg Center for the Environment (HCE), focusing on the Rhine-Neckar district and the city of Heidelberg. The aim of the explorative project was to generate a first overview on greenhouse gas emission data in order to initiate climate action of various actors and to provide well-founded support by using accurate infor-mation. The focus during the pilot phase was on the collection, compilation and evaluation of the quality of heterogeneous data sets and methods for a greenhouse gas emission inventory, as well as on the information preparation and evaluation of different inventory and presentation options. These should in turn be adapted to the needs of different users and fields of applica-tion. The study focused on different German approaches to greenhouse gas accounting, espe-cially in Baden-Württemberg compared to other German states, and in detail on the City of Heidelberg compared to the surrounding municipalities in the Rhine-Neckar district. The over-arching goal is to use the results beyond the case study projected here as a stimulus and pre-liminary work for further projects and activities in the overall "Climate Action Science" project. Several difficulties were encountered in processing the emissions inventory and compiling var-ious data sets on emissions in the study area. Three basic situations were identified: 1. De-sired data is not available (measurements required), 2. Desired data is not freely accessible (stakeholder involvement), 3. Data generation via proxy data. In the pilot phase, we imple-mented a transdisciplinary approach regarding situation 2. In this way, emission maps on dif-ferent information levels could be created for the study area and applied in psychological ex-periments. Thus, first insights into the perception and processing of emission information on the user level could be gained

The C-glycosyltransferase IroB from Pathogenic Escherichia coli: Identification of Residues Required for Efficient Catalysis

The E. coli C-glycosyltransferase IroB catalyzes formation of a C-C bond between enterobactin and the glucose moiety of UDP-glucose, resulting in the production of mono-, di- and tri-glucosylated enterobactin (MGE, DGE, TGE). To identify catalytic residues, we generated a homology model of IroB from aligned structures of two similar C-glycosyltransferases as templates. Superposition of our homology model onto the structure of a TDP-bound orthologue revealed residue W264 as a possible stabilizer of UDP-glucose. D304 in our model was located near the predicted site of the glucose moiety of UDP-glucose. A loop containing possible catalytic residues (H65, H66, E67) was found at the predicted enterobactin-binding site. We generated IroB variants at positions 65-67, 264, and 304 and investigated variant protein conformations and enzymatic activities. Variants were found to have Tm values similar to wild-type IroB. Fluorescence emission spectra of H65A/H66A, E67A, and D304N were superimposable with wild-type IroB. However, the emission spectrum of W264L was blue-shifted, suggesting solvent exposure of W264. While H65A/H66A retained activity (92% conversion of enterobactin, with MGE as a major product), all other IroB variants were impaired in their abilities to glucosylate enterobactin: E67A catalyzed partial (29%) conversion of enterobactin to MGE; W264L converted 55% of enterobactin to MGE; D304N was completely inactive. Activity-impaired variants were found to bind enterobactin with affinities within 2.5-fold of wild-type IroB. Given our outcomes, we propose that IroB W264 and D304 are required for binding and orienting UDP-glucose, while E67, possibly supported by H65/H66, participates in enterobactin/MGE/DGE deprotonation