Beiträge zur Chemie Schiff’scher Basen mit Aminosäuren und deren Metallkomplexe

Ziel der vorliegenden Arbeit war die Synthese und vollständige Charakterisierung von Schiff‘sche Base-Liganden mit ortho-Vanillin als Aldehydquelle und ausgewählten Aminosäuren als Aminquelle. Diese Liganden, entweder in Reinform oder in situ generiert, sollten anschließend mit verschiedenen Metallsalzen zu Metallkomplexen umgesetzt werden. Dabei sollten messbare Einkristalle der Komplexe erhalten werden, um eine sichere Strukturaufklärung zu ermöglichen. Die erhaltenen Liganden und Komplexe sollten, wenn angebracht, hinsichtlich ihres biologischen Potenzials untersucht werden. Es konnten Liganden mit L-Glutaminsäure, L-Tyrosin und L-Glutamin als Natriumsalze in hohen Ausbeuten erhalten und vollständig charakterisiert werden. Untersuchungen zur Stabilität mittels 1H-NMR-Spektroskopie zeigten, dass alle Liganden in wässriger Lösung teilweise in ihre Edukte zerfallen und sich ein Gleichgewicht einstellt. In Studien zum antimikrobiellen Potenzial der Liganden mit L-Glutaminsäure und L-Tyrosin konnte gezeigt werden, dass die Liganden antimikrobielle Aktivität gegenüber verschiedenen Mikroorganismen, insbesondere Hefepilzen der Gattung Candida besaßen. Allerdings war diese Aktivität auf ortho-Vanillin zurückzuführen, welches durch den Zerfall des Liganden in wässrigem Milieu freigesetzt wurde. Nennenswerte antiproliferative Eigenschaften gegenüber Zellen der Linien L929 und Hep G2 konnten in MTT-Tests nicht beobachtet werden. Die Umsetzung des L-Glutaminsäure-haltigen Liganden mit Metallsalzen lieferte folgende Komplexe: • Mit Nickel(II)-chlorid wurde ein pentadecanuklearer Ni(II)-Komplex in Form eines Rades erhalten, welcher ein seltenes Beispiel für ungeradzahlige radförmige Ni(II)-Komplexe darstellt. Dieser Komplex war stabil in Methanol bzw. einem Wasser/Methanol-Gemisch und nur schwach zytotoxisch gegenüber L929- und B16-Zellen. Die Untersuchung der magnetischen Eigenschaften zeigte ein dominantes antiferromagnetisches Verhalten, sowie intermolekulare Wechselwirkungen bei Temperaturen unterhalb von 24 K. • Mit Kupfer(II)-sulfat und unter Zugabe von Salzsäure am Ende der Reaktion konnte ein tetratnuklearer Cu(II)-Komplexe mit stark verzerrter Heterokubanstruktur erhalten werden, welcher über den betrachteten Zeitraum von 48 h stabil blieb. Die Aminosäurereste waren nicht an der Koordination der Metallzentren beteiligt. Der Komplex zeigte milde bis moderate antibakterielle Aktivität, sowie gute antifungale Aktivität gegenüber Organsimen der Gattung Candida. Gegenüber L929- und Hep G2-Zellen konnte eine moderate Zytotoxizität beobachtet werden. • Mit Eisen(III)-perchlorat wurden zwei mononukleare anionische Fe(III)-Komplexe, bei denen entweder Natrium oder Kalium das Gegenion darstellte, erhalten. Von dem Kalium-haltigen Komplex konnte keine eindeutige Kristallstruktur gewonnen werden. XRPD-Studien lassen aber eine Isostrukturalität vermuten. Das Eisenzentrum war verzerrt-oktaedrisch von zwei Ligandmolekülen umgeben. Mittels EPR wurde ein Spin von S = 5/2 nachgewiesen. • Mit Palladium(II)-chlorid konnten zwei mononukleare Pd(II)-Komplexe erhalten werden, in denen das Palladiumzentrum quadratisch-planar von einem Ligandmolekül und einem Chloridion koordiniert wird und insgesamt einfach negativ geladen ist. Zur Kompensation der Ladung dienten entweder ein Natrium- oder ein Kaliumion. Abhängig vom Gegenion konnte eine unterschiedliche Packung in der Kristallstruktur beobachtet werden. Der hinsichtlich seines biologischen Potenzials untersuchte Kalium-haltige Komplex war stabil in DMSO über den untersuchten Zeitraum von 72 h und zeigte moderate bis gute antimikrobielle Aktivität. Gegenüber Zellen der Linie L929 war der Komplex inaktiv. Untersuchungen an weiteren humanen Krebszelllinien stehen noch aus. Bei der Umsetzung des L-Glutamin-haltigen Liganden konnten nur mit Eisen(III)-perchlorat Komplexe erhalten werden. Dabei war der Zusatz von Natrium- bzw. Kaliumazid essentiell für das Wachstum von Kristallen. Die Komplexe waren von Struktur und Eigenschaften her analog zu den Komplexen mit dem L-Glutaminsäure-haltigen Ligand. Allerdings konnten hier die Kristallstrukturen der Komplexe mit beiden Gegenionen, Kalium und Natrium, erhalten werden Diese unterschieden sich durch die Packung im Festkörper. Für den L-Tyrosin-haltigen Liganden konnten Komplexe mit Nickel und Palladium erhalten werden: • Mit Nickel(II)-chlorid wurden zwei Metallkomplexe erhalten, welche isostrukturell sind und sich nur durch das koordinierte Lösungsmittel, Methanol oder DMF, unterschieden. Die Komplexe waren tetranuklear und zeigten als Strukturmotiv nicht den üblichen Ni-O-Heterokuban, sondern eine äußerst seltene schüsselartige Struktur. Dabei blieben die Tyrosin-Seitenketten ungebunden. Beide Solvate erwiesen sich sowohl in Lösung als auch im festen Zustand als stabil • Mit Palladium(II)-chlorid konnten zwei mononukleare Pd(II)-Komplexe mit quadratisch-planarer Geometrie um das Palladiumzentrum erhalten werden. Die Koordinationssphäre wurde entweder durch ein Chloridion oder ein Wassermolekül vervollständigt. Im Falle des chlorhaltigen Komplexes kompensierte ein Natriumion die negative Ladung. Der Komplex mit dem koordinierten Wassermolekül war insgesamt neutral. Während der neutrale Komplex in DMSO über 72 h stabil blieb, zeigte der anionische Komplex Zerfallsprodukte im 1H-NMR-Spektrum. Beide Komplexe wiesen moderate bis gute antimikrobielle Aktivität auf. Gegenüber Zellen der Linie L929 waren beide Komplexe inaktiv. Untersuchungen an weiteren humanen Krebszelllinien stehen noch aus. Die geplante Synthese einer Schiff’schen Base durch die Kondensationsreaktion von ortho-Vanillin und L-Cystein war, anders als in diversen Publikationen behauptet, nicht erfolgreich. Stattdessen wurde das entsprechende Thiazolidin als Racemat erhalten. Die Umsetzung mit verschiedenen Metallsalzen lieferte keine Metallkomplexe in kristalliner Form. Allerdings konnten durch Zugabe von Zinkchlorid messbare Kristalle des Thiazolidins erhalten werden. Obwohl das gesamte kristalline Präzipitat racemisch war, wurde in mehreren Messungen nur die Struktur des 2R,4R-Diastereomers bestimmt. Dieses lag im Kristall als Zwitterion vor. Zusammenfassend konnten insgesamt drei Schiff’sche Basen als Natriumsalze synthetisiert und charakterisiert werden. Die Umsetzung der Liganden mit Metallsalzen führte zu einer Vielzahl von neuen Metallkomplexen, die eine hohe strukturelle Vielfalt und interessante Eigenschaften aufwiesen

Determining Deuterium Polarization via Nuclear Magnetic Resonance

Dynamic Nuclear Polarization (DNP) is a method by which the spins of electrons are specifically targeted by microwaves at resonance frequency in order to induce spin flips. Occasionally, the electron spins couple with nuclear spins and nuclear spin flips are induced. The relaxation time of the electron is significantly lower than that of the nuclei, which allows for large polarization. The main goal of the Slifer Lab is to utilize specifically prepared crystalline structures in order to separate the convoluted energy transitions ( Batman Peak ) in the deuterium\u27s nuclear magnetic resonance (NMR) signal, which would allow for tensor enhancement of deuterium. The goal of this project was to determine the polarizations of deuterium under different conditions from a previously taken experimental data and to determine a calibration constant that scales the area under an NMR curve to the polarization. Also, by determining the polarization of deuterium by separate methods, the calibration constant and an independent ratio method, the consistency of the data is checked. The ratio method produced a polarization (0.23287671) that was almost double (~1.73x) that of the calibration constant (0.13569978). The ratio method is similar to that of a trusted, independent line-shape method, which indicates an error in the determination of the calibration constant. The source of these issues will be explored further at the end of this paper

Assessment of the Opportunities and Challenges for the Adoption of E-Banking Service in Ethiopia: A study with reference to selected commercial Banks

Despite the growth of e-banking adoption worldwide, Ethiopian banks continue to conduct most of their banking transactions using traditional methods. The general objective of the study was assessment of the current extent and practices, benefits realized by banks, driving forces, opportunities and challenges for the adoption of e-banking service in Ethiopia. From this general objective, five specific issues were explored. An exploratory research design was employed to conduct this study. Both primary and secondary qualitative data were collected for the purpose of this study from the IT manager’s of each bank at the head office level and bank web sites respectively. The collected data was analyzed by using descriptive analysis such as tables and percentages. From an analysis of the collected data, the findings revealed that: balance inquiry, cash withdrawal, funds transfers, statement printing are among the major practice of e-banking among those banks that are providing the service to the customer. The different e-banking channels by which banks are using to provide these services to the customer are ATM card, debit card, credit card, salary card, visa card, master card, Internet banking and Mobile or SMS banking. Cost reduction, coverage of wide geographical area, customer satisfactions etc are among the benefits of adopting the system from the viewpoint of the bank. Among the different driving forces that initiate banks to adopt e-banking services: existence of high competition in the banking industry, desire to improve organizational performance, desire to reduce transaction cost, desire to cover wide geographical area, and desire to build organizational reputation are among others. Chances of risk, Lack of suitable legal and regulatory framework, absence of financial networks that links different banks, Low level of internet penetration and poorly developed telecommunication infrastructure, high cost of internet, security concerns are among the major challenges for the adoption of e-banking service in the country. However, late adopter opportunities, improvement in the banking habit of the society, commitment of the government to facilitate the expansion of ICT infrastructure and willingness among banks to cooperate in building infrastructure are the major opportunities for the adoption of the system in the banking industry

Evaluation of Bread Wheat Genotypes for Adult Plant Resistance to Stem Rust

Wheat stem rust (Puccinia graminis f. sp tritici)  also known as 'polio of agriculture' is a ravaging disease of wheat (Triticum aestivum L.) making it a foremost confront to wheat production in Ethiopia and other wheat producing countries of the world due to the frequently evolving of virulent pathogen races. Because of this, searching novel genes in wheat genotypes is a critical issue. Twenty eight advanced bread wheat genotypes were evaluated for their response against stem rust caused by Puccinia graminise under field conditions at Kulumsa and Asassa during 2018 main growing season. Evaluation was carried out through disease assessment including terminal stem rust severity (TRS) and coefficient of infection (ACI) under natural infection. Twenty two wheat genotypes viz; ETBW-8858, ETBW-8870, ETBW-8583, ETBW-8684, ETBW-9548, ETBW-9549, ETBW-9554, ETBW-9558, ETBW-9559, ETBW-9560, ETBW-8751, ETBW-8862, ETBW-8804, ETBW-8896, ETBW-8991, ETBW-9560, ETBW-9556, ETBW-9486, ETBW-9561, ETBW-9550, ETBW-9553 and ETBW-9555 out of twenty-eight evaluated genotypes were discovered to be adult plant resistant (TRS < 30 and ACI < 20 ) to stem rust disease at both screening sites. Therefore, these genotypes with high stem rust resistance could be backcrossed to widely acclimatized and high yielding but susceptible Ethiopian wheat varieties to prevent further wheat yield declines. However, may need to evaluate for seedling response to confirm whether the genotypes are true adult plant resistant. Keywords: Adult plant, Puccinia graminis, Stem rust, TRS, Wheat genotypes. DOI: 10.7176/FSQM/103-03 Publication date: December 31st 202

Detection of Aflatoxins from Malt Barley Under Storage Conditions in Central Ethiopia

Aflatoxins are non avoidable highly poisonous and carcinogenic auxiliary metabolite produced by some molds belonging to Aspergillus genera on range of agricultural products including malt barley. This study was conducted with the aim to examine total aflatoxin (AFT) concentration in malt barley samples. A total of eighty seven malt barley samples collected from farmers' stores and seed enterprises' of Amhara and Oromia regions were employed for aflatoxin analysis through an ELISA test. Of these, 30 (34.48%) were positive whereas the remaining 57 (54.03%) were negative. The total aflatoxin levels in the positive samples layover in a range between 0.0005μgkg-1 and 0.04μgkg-1.The existing results undoubtedly revealed insignificant contamination of malt barley samples in Ethiopia, suggesting that concentrations were low enough and ensure compliance with the Food and Agricultural Organization of the United Nations (FAO) 20 ugkg-1, World Health Organization (WHO) 15 μgkg-1 and European Union (EU) 4-15ugkg-1 admitted levels depending on the raw material use of cereals. Fortunately, the result of this study may not lead to infer the urgent need to apply control measures against aflatoxigenic fungi and associated aflatoxins that could result adverse effects. The major factors for less contamination of malt barley by aflatoxin were expected to be pre- and post-harvest environmental factors, mechanized harvesting and proper management practices like drying before storage. Although the present status of aflatoxins is remarkably at lower concentrations, regular and accurate cereal quality testing is critical to reduce the risk of severe health problems as well as international trade repercussions. Keywords: Adverse effect, Auxiliary metabolite, Contamination, ELISA, Molds. DOI: 10.7176/JBAH/10-15-01 Publication date:August 31st 202

Exploring chlorophyll-a satellite derived data to characterise the coastal waters of the south of Portugal

The chlorophyll-a (Chl-a) concentration can be used as the main indicator of the productivity, trophic condition, and proxy of phytoplankton biomass in coastal, and oceanic waters. This ecological indicator will provide useful information for reliable monitoring systems and government policy (e.g., European directives); however, assessment of Chl-a using in situ measurements in coastal and oceanic waters has some economic challenges and gives a restricted view of the dynamics of the phytoplankton. To overcome this limitation this study used Chl-a datasets from the Copernicus Marine Environment Monitoring Service (CMEMS), that provide merged multi-sensor ocean colour products. This study aimed to characterise the inter-annual variability of the Chl-a concentration retrieved by multi-ocean colour sensors data and relate these variabilities to the coastal environmental changes in five stations in the south coast of Portugal. Statistical analyses were performed to help the understanding and the characterisation of Chl-a at the coastal water stations along the southern Portugal coast based on 17 years of data (2002-2019). In addition, a comparison between Chl-a and physical (sea surface temperature (SST)) and chemical (nutrients) parameters were made to understand the inter-annual variability in these coastal waters. The extracted Chl-a values in the study area showed a seasonal cycle where the Chl-a is triggered in early spring. A clear negative relationship between Chl-a and SST was found in all stations. In the study area, a positive correlation was found between Chl-a and nutrients (NH4+, NO3-, PO4-3, and SiO4-4). Results show that SST and nutrients influence the Chl-a concentration availability in the study area. The Chl-a retrieved by satellite data reveals to be an efficient alternative tool and valuable approach to study environmental conditions of the coastal water, especially in response to eutrophication, which is the common management issue in coastal waters.I am also thankful to Prof. Alice Newton, Prof. Elena Fabbri, and Prof. Irene Laiz who is the EMJMD WACOMA Coordinators for all their considerate guidance, kindness, and support during the tenure. I also pay my sincere thanks to all WACOMA technical staff and administrative staff for their support, tolerance, and encouragement

Analysis of Household Level Determinants of Food Security in Jimma Zone, Ethiopia

The study look for examining food security status of rural households in Gomma District in south western Ethiopia. Household caloric acquisition method was used to measure the status of food security. Household survey was conducted on 190 households and based on these households binary logistic regression model was estimated. Variables related like age, income from off farm/non-farm activities, size of cultivated land, livestock and oxen ownership were found to have positive impact for the attainment of household food security. Likewise use of chemical fertilizer and soil and water conservation practice were found to have positively affecting household food security in the study area. The finding indicated that development interventions that aimed to encourage older households to share their experience to younger households, diversify income of the households, improving productivity of land and livestock, improving the supply and access of chemical fertilizer, incentives to use soil and water conservation activities are found to improve the food security status of the households , thus concerned bodies need to do access and that aimed to diversify income of the households, improving the supply of chemical fertilizer , improving the productivity of land and livestock will have paramount importance for the attainment of household food security. Generally, this study has implication that attaining household food security in southwestern Ethiopia needs mixed adoption of policies and strategies. Keywords: Correlates, Food insecurity, Ethiopia, Determinan

Living on the Margin of Life: The Condition of Street Children During Covid-19 Outbreak in Three Selected Towns of SNNPR (Sodo, Jinka, and Arbaminch)

The objective of this study is to assess the socio-economic impacts of the COVID-19 crisis on street children, their awareness about COVID-19 transmission and support of government to street children in three selected towns of SNNPR (Jinka, Arbaminch, and Sodo). To achieve these objectives, concurrent mixed research designs were employed. To identify respondents, both convenience and purposive sampling techniques were used. Data were collected from both primary and secondary sources. As instruments of data collection; interview schedules, in-depth interviews, focus group discussions and key informant interviews were used. Finally, data were analyzed and interpreted using descriptive statistics and thematic analysis. The finding of the study depicted that the outbreak of COVID-19 worsen the social and economic problem of street children. Despite the social and economic impacts of COVID-19, no permanent support was given to the children both by the government and charity organizations. Moreover, the finding showed that street children suffer from various problems like lack of basic needs, depression and deprivation of work opportunity. Thus, holistic intervention should be used to address various problems that street children faced