Master of Science

thesisCu2ZnSnS4 (CZTS) is a semiconductor material made of nontoxic, earth abundant elements, making it a promising topic of research for absorber layers in thin film solar cells. We observed that rapid thermal annealing of tin (Sn)-rich co-sputtered CZTS films resulted in crystalline, hexagonal platelets of tin-disulfide (SnS2) 5-30 μm long at the surface of the film. In this work, the formation mechanisms of these surface crystallites and their implications for CZTS absorber layer processing were investigated. The formation and decomposition of these platelets were studied by observing the changes in their structural, morphological, compositional, and vibrational properties accompanying the imposition of lateral temperature gradients as well as different annealing atmospheres. The homogeneous co-sputtered films were annealed in a graphite boat in a quartz reactor using a base heater and halogen lamp. Interrupting annealings to examine stages of crystal formation showed at around 400 oC SnS2 began to form on the surface of films. Near the edges of the film, where temperatures were found to be higher, crystals melted into an amorphous unknown tin-sulfide phase. Diffusion of species from the film into the base of the crystals formed long CZTS grains of which the amorphous phase left behind as it coalesced. Annealing without sulfur (S) increased Sn and S losses from the film and increased the number of crystals nucleated on the surface of the film. For solar cell device applications of CZTS thin films, removal of these SnS2 iv surface crystallites is necessary; thus wet chemical and thermal decomposition etching techniques were studied. Wet etching attempts with KCN and NH4OH solutions did little to etch crystals. HCl solution damaged the CZTS film as much as the crystals and therefore was also unsuitable. Thermal etching by evacuating the chamber near the end of annealing transformed the SnS2 crystals into a grainy, S-poor Sn phase via the decomposition of SnS2 by removing the vapor species with which it is in equilibrium. Understanding the role of Sn species during annealing is important for the complex CZTS system because small deviations from Sn stoichiometry results in drastic changes in the secondary phases and microstructure of the film. The experiments and insight provided in this thesis represent unexplored unconventional methods toward CZTS growth and different approaches for CZTS processing for development of thin film solar cell technology

Water Resources of Part of Canyonlands National Park, Southeastern Utah

Canyonlands National Park is in about the center of the Canyon Lands section of the Colorado Plateaus physiographic province in southeastern Utah. The part of the park discussed embraces an area of about 400 square miles comprising isolated mesas, precipitous canyons, and dissected broad benches near the confluence of the Green and Colorado Rivers, the only perennial streams in the area. The climate is arid to semiarid; normal annual precipitation ranges from less than 8 to about 10 inches. Potential evapotranspiration is about 41 inches annually. Geology of the park is characterized by nearly horizontal strata that dip gently northward. Exposed rock formation*and deposits range in age from Middle Pennsylvanian to Holocene. Owing to the elevated and deeply dissected topography, only parts of the Cedar Mesa and White Rim Sandstone Members of the Cutler Formation of Permian age have potential for development of wells. Strata above and below them support only small -springs, are dry, or contain brine

Charakterisierung der Drosophila melanogaster annexin Gene

Annexine bilden eine Familie Calcium- und Phospholipidbindender Proteine. Für die zwölf Annexine der Vertebraten sind Aufgaben innerhalb endozytotischer, exozytotischer, und membranstabilisierender Prozesse beschrieben. Die physiologische Relevanz einzelner Annexine herauszustellen ist dementsprechend schwierig. Da die Drosophila annexine b9, b10 und b11 in ihrer Struktur den Vertebratenvertretern sehr ähnlich sind, kann eine detaillierte Charakterisierung dieser zum Verständnis der gesamten Familie beitragen. Innerhalb dieser Arbeit konnte gezeigt werden, dass die Annexine B9, B10 und B11 als lösliche Proteine im Zytosol und in Verbindung mit der Plasmamembran vorliegen. Die Reduktion der Annexin-Expression mittels RNAi führt in allen betrachteten Geweben zu schweren Zelldefekten, die auf Apoptose beruhen. Es konnte gezeigt werden, dass dies nicht auf einen offensichtlichen Einfluss auf die Zellpolarität, das Aktin- und Spectrin-Zytoskelett oder die Zytokinese zurückzuführen ist

Detection of Tumor Cell-Specific mRNA in the Peripheral Blood of Patients with Breast Cancer-Evaluation of Several Markers with Real-Time Reverse Transcription-PCR

It is widely known that cells from epithelial tumors, e. g., breast cancer, detach from their primary tissue and enter blood circulation. We show that the presence of circulating tumor cells (CTCs) in samples of patients with primary and metastatic breast cancer can be detected with an array of selected tumor-marker-genes by reverse transcription real-time PCR. The focus of the presented work is on detecting differences in gene expression between healthy individuals and adjuvant and metastatic breast cancer patients, not an accurate quantification of these differences. Therefore, total RNA was isolated from blood samples of healthy donors and patients with primary or metastatic breast cancer after enrichment of mononuclear cells by density gradient centrifugation. After reverse transcription real-time PCR was carried out with a set of marker genes (BCSP, CK8, Her2, MGL, CK18, CK19). B2M and GAPDH were used as reference genes. Blood samples from patients with metastatic disease revealed increased cytokine gene levels in comparison to normal blood samples. Detection of a single gene was not sufficient to detect CTCs by reverse transcription real-time PCR. Markers used here were selected based on a recent study detecting cancer cells on different protein levels. The combination of such a marker array leads to higher and more specific discovery rates, predominantly in metastatic patients. Identification of CTCs by PCR methods may lead to better diagnosis and prognosis and could help to choose an adequate therapy

Production of annual ryegrass with different doses of nitrogen fertilization in topdressing.

Made available in DSpace on 2019-12-30T18:10:48Z (GMT). No. of bitstreams: 1 SeminaCiAgMittelmannProduction.pdf: 363245 bytes, checksum: 39152185b5b3d0a8133d04e3c3e2af64 (MD5) Previous issue date: 2019bitstream/item/207926/1/SeminaCiAg-Mittelmann-Production.pd

Near-field coded-mask technique and its potential for proton therapy monitoring

Objective. Prompt-gamma imaging encompasses several approaches to the online monitoring of the beam range or deposited dose distribution in proton therapy. We test one of the imaging techniques - a coded mask approach - both experimentally and via simulations. Approach. Two imaging setups have been investigated experimentally. Each of them comprised a structured tungsten collimator in the form of a modified uniformly redundant array mask and a LYSO:Ce scintillation detector of fine granularity. The setups differed in detector dimensions and operation mode (1D or 2D imaging). A series of measurements with radioactive sources have been conducted, testing the performance of the setups for near-field gamma imaging. Additionally, Monte Carlo simulations of a larger setup of the same type were conducted, investigating its performance with a realistic gamma source distribution occurring during proton therapy. Main results. The images of point-like sources reconstructed from two small-scale prototypes' data using the maximum-likelihood expectation maximisation algorithm constitute the experimental proof of principle for the near-field coded-mask imaging modality, both in the 1D and the 2D mode. Their precision allowed us to calibrate out certain systematic offsets appearing due to the limited alignment accuracy of setup elements. The simulation of the full-scale setup yielded a mean distal falloff retrieval precision of 0.72 mm in the studies for beam energy range 89.5–107.9 MeV and with 1 × 10$^{8}$ protons (a typical number for distal spots). The implemented algorithm of image reconstruction is relatively fast—a typical procedure needs several seconds. Significance. Coded-mask imaging appears a valid option for proton therapy monitoring. The results of simulations let us conclude that the proposed full-scale setup is competitive with the knife-edge-shaped and the multi-parallel slit cameras investigated by other groups

Methylated APC and GSTP1 genes in serum DNA correlate with the presence of circulating blood tumor cells and are associated with a more aggressive and advanced breast cancer disease

<p>Abstract</p> <p>Background</p> <p>Tumor-related methylated DNA and circulating tumor cells (CTC) in the peripheral blood might be of prognostic importance in breast cancer. Thus, the aim of our study was to examine free methylated DNA and CTC in the blood from breast cancer patients and to correlate it with clinicopathological features known to influence prognosis.</p> <p>Materials and methods</p> <p>We prospectively obtained serum samples from 85 patients with breast cancer and 22 healthy volunteers. Sera were analysed by methylation specific PCR (MethyLight PCR) for five genes: adenomatous polyposis coli (APC), ras association domain family protein 1A (RASSF1A), estrogen receptor 1 (ESR1), CDKN2A (p16) and glutathione s-transferase pi 1 (GSTP1). Beta actin (ACTB) served as control. In parallel matched peripheral blood of 63 patients was used to assay for circulating tumor cells in the peripheral blood by a modified immunomagnetic AdnaTest BreastCancerSelect with PCR detection for EPCAM, MUC1, MGB1 and SPDEF.</p> <p>Results</p> <p>We found a hypermethylation in the APC gene in 29% (25/85), in RASSF1A in 26% (22/85), in GSTP1 in 18% (14/76) and in ESR1 in 38% (32/85) of all breast cancer patients. No hypermethylation of CDKN2A was found (0/25). Blood samples of patients were defined CTC positive by detecting the EPCAM 13% (8/63), MUC1 16% (10/63), MGB 9% (5/55), SPDEF 12% (7/58) and in 27% detecting one or more genes (15/55). A significant difference was seen in methylated APC DNA between cancer patients and healthy volunteers. Moreover, methylated APC, RASSF1 and CTC were significantly different in metastatic versus non-metastatic disease. In addition, the presence of methylated APC, RASSF1A and CTC correlated significantly with AJCC-staging (p = 0.001, p = 0.031 and 0.002, respectively). High incidences of methylations were found for the genes RASSF1 and ESR1 in healthy individuals (both 23% 5/22). Methylated GSTP1 was predominantly found in the serum of patients with large primaries (p = 0.023) and was highly significantly correlated with positive Her2/<it>neu </it>status (p = 0.003). Elevated serum CA15.3 was strongly correlated with methylated APC and CTC detection (both p = 0.000). Methylated ESR1 failed to exhibit significant correlations with any of the above mentioned parameters. The presence of CTC in peripheral blood was significantly associated with methylated APC (p = 0.012) and methylated GSTP1 (p = 0.001).</p> <p>Conclusion</p> <p>The detection of methylated APC and GSTP1 DNA in serum correlated with the presence of CTC in the blood of breast cancer patients. Both methylated DNA and CTC correlated with a more aggressive tumor biology and advanced disease.</p