Organische Chemie
2'-Desoxyisoguanosin: Synthese, Desoxygenierung und Einbau in Oligonucleotide
Diplomarbeit aus dem Jahr 1993 im Fachbereich Chemie - Organische Chemie, Note: 1,5, Universität Osnabrück, Sprache: Deutsch, Abstract: 1) 2'-Desoxyisoguanosin (1) wurde in einer zweistufigen Synthese dargestellt. Zu diesem Zweck wurde 2'-Desoxyguanosin (3) zunächst in 2-Amino-2'-desoxyadenosin (5) überführt. Dieses wurde in 2'-Desoxyisoguanosin (1) umgewandelt. Bei der Reaktion von 2'-Desoxyisoguanosin (1) mit Chloracetaldehyd bildete sich N6-Etheno-2'-desoxyisoguanosin (9). Dieses zeigte mit N6-Ethenoadenosin (6) vergleichbare Fluoreszenzeigenschaften. 2) 2',3'-Didesoxyisoguanosin (2) konnte über den photochemischen Austausch des 2-Substituenten von 2-Chlor-2',3'-didesoxyadenosin (20) dargestellt werden. Verbindung 20 konnte über zwei Synthesewege gewonnen werden: Anfänglich ausgehend von 2-Chlor-2'-desoxyadenosin (16) über Barton-Desoxygenierung in 27 % Gesamtaubeute über vier Stufen. Alternativ wurde in einem konvergenten Syntheseweg der 2',3'-Didesoxyzucker 21 mit 2,6-Dichlorpurin (23) unter Mitsunobu-Bedingungen umgesetzt. Durch nachfolgenden Austausch des 6-Substituenten gegen NH2 waren die anomeren 6-Amino-2-chlor-2',3'-didesoxynucleoside (25a, 25b) zugänglich. 3) Mit Hilfe der Festphasensynthese wurde das Oligomer d(iG-C)3 (32) synthetisiert und seine Zusammensetzung durch enzymatische Hydrolyse bewiesen. Anhand des Tm-Wertes von 29 °C konnte die iGd-dC-Basenpaarung nachgewiesen werden. Da alternierende iGd-dC -Sequenzen nur unter paralleler Strangorientierung selbstkomplementär sind, resultiert im Vergleich zu d(G-C)3 (33) der Verlust eines Basenpaares. Der parallele Duplex von d(iG-C)3 wies mit 29°C einen geringeren Tm-Wert als d(G-C)3 (45°C) auf. Mit Hilfe von Inkrementberechnungen für die freie Enthalpie pro Basenpaar, konnte bewiesen werden, daß diese Destabilisierung von d(iG-C)3 (32) durch die Einbuße eines Basenpaares ausgelöst wurde.
Acetylsalicylsäure: Die Synthese des Medikamentes auf zwei verschiedenen Wegen sowie die Stoffeigenschaften
Facharbeit (Schule) aus dem Jahr 2022 im Fachbereich Chemie - Organische Chemie, Note: 1, , Sprache: Deutsch, Abstract: Entdecken Sie die faszinierende Welt der Acetylsalicylsäure (ASS) und begeben Sie sich auf eine Reise durch die chemischen Prozesse, die hinter diesem allgegenwärtigen Schmerzmittel stehen. Diese umfassende Facharbeit enthüllt die Geheimnisse der ASS-Synthese, indem sie zwei unterschiedliche Synthesewege detailliert untersucht und vergleicht. Von der sorgfältigen Isolierung der ASS aus handelsüblichen Tabletten bis hin zur präzisen Synthese im Labor werden alle Schritte anschaulich und nachvollziehbar dargestellt. Tauchen Sie ein in die Welt der organischen Chemie und erlernen Sie die Kunst der Reinheitsbestimmung, wobei Dünnschichtchromatographie und Schmelzpunktbestimmung als zuverlässige Werkzeuge zur Qualitätskontrolle dienen. Erfahren Sie, wie die chemischen Eigenschaften von ASS, ihre Struktur als Carbonsäure und Ester sowie ihre Reaktionen wie die Hydrolyse ihre Wirksamkeit und Stabilität beeinflussen. Die Arbeit beleuchtet nicht nur die theoretischen Grundlagen, sondern legt auch großen Wert auf die praktische Anwendung und die Bedeutung von Sicherheitsvorkehrungen im Labor. Durch den Vergleich der beiden Synthesewege werden Vor- und Nachteile aufgezeigt und Verbesserungspotenziale für eine optimierte Ausbeute und Reinheit diskutiert. Diese Abhandlung ist somit ein unverzichtbarer Leitfaden für angehende Naturwissenschaftler und alle, die ein tieferes Verständnis für die Chemie der Acetylsalicylsäure und die Prinzipien des wissenschaftlichen Arbeitens im Labor erlangen möchten. Lassen Sie sich von der Präzision und Sorgfalt dieser Untersuchung begeistern und erweitern Sie Ihr Wissen über die Welt der Moleküle und Reaktionen. Ob Student, Lehrer oder einfach nur neugierig - diese Arbeit bietet Ihnen einen fundierten Einblick in die Synthese, die chemischen Eigenschaften und die Reinheitsbestimmung von Acetylsalicylsäure und vermittelt gleichzeitig die essenziellen Grundlagen für sicheres und erfolgreiches Experimentieren.
An analysis on the dendral expert system
Seminar paper from the year 2013 in the subject Chemistry - Organic Chemistry, Lovely Professional University, Punjab (School of computer science), course: MTech C.S.E, language: English, abstract: In this paper, we do an analysis on the influential pioneer project in the application area of Heuristic programming for experimental analysis in empirical science using IUPAC conventions. The primary aim of the DENDRAL project was to help organic chemists in identifying unknown organic molecules from compounds extracted from known origin that had medicinal or utility value. The process was done by analysing their mass spectra and then undergoing comparative study using knowledge of chemistry. It was done at Stanford University by Edward Feigenbaum, Bruce Buchanan, Joshua Lederberg, and Carl Djerassi. It began in 1965 and spans approximately half the history of AI research. The DENDRAL Project was one of the first large-scale programs to embody the strategy of using detailed, task-specific knowledge about a problem domain as a source of heuristics, and to seek generality through automating the acquisition of such knowledge.
Analyse von Koffein und Taurin in Energy-Drinks
Wissenschaftliche Studie aus dem Jahr 2015 im Fachbereich Chemie - Biochemie, , Sprache: Deutsch, Abstract: Analytische Untersuchung ausgewählter Energy-Drinks durch HPLC-Chromatographie. Bestimmung der absoluten Konzentrationen von Koffein und Taurin und Darstellung der HPLC-Chromatogramme.
Assessment of Cadmium in Chicken Meat and Offal. Food Safety and Food Poisoning
Project Report from the year 2015 in the subject Chemistry - Food Chemistry, grade: A, University of Ibadan, course: Zoology, language: English, abstract: This study was carried out on the evaluation of cadmium in chicken meat and offal in Bodija, Sango and Ojoo markets in Ibadan between July and October, 2015. The appraisal was aimed at assessing the cadmium that can be accumulated in the kidney, liver, intestine, blood, muscle and the feathers. Ten mature chickens were bought and dissected to remove the chicken meat and offal samples. This samples were oven-dried separately and pulverised into powdered form through grinding with a mortar and pestle. These were acid-digested for cadmium analyses using Buck Scientific 210 VGP Atomic Absorption Spectrophotometer. The results showed varying mean concentrations in the intestine (0.713±0.024 ppm), feather (0.702±0.035 ppm) and muscle (0.592±0.019 ppm) with low mean concentrations in the blood (0.426±0.032 ppm), liver (0.432±0.021 ppm) and kidney (0.352±0.027 ppm). Most of the chicken meat and offal samples were above the WHO guideline limit of 0.05 ppm. The Target Hazard Quotient (THQ) from the study was below 1 which is indicative that the general populace in this study area is not at risk. It is therefore recommended that regular biomonitoring should be carried out on chicken meat and offal locally and globally for the purpose of food safety.
Biochemical Characterization of Cotton Hybrids and their Parents
Master's Thesis from the year 2022 in the subject Chemistry - Bio-chemistry, , course: biochem-599 - Agriculture, language: English, abstract: Unlock the secrets hidden within the genetic tapestry of cotton! Venture into the intricate world of Gossypium hirsutum and discover the biochemical keys that unlock superior hybrid vigor. This groundbreaking work meticulously dissects the biochemical composition of cotton hybrids and their parent lines, revealing the subtle yet significant differences that drive yield and fiber quality. Explore a comprehensive analysis of key biochemical parameters, including reducing sugar, total soluble sugar, protein content, proline levels, tannin concentrations, gossypol percentages, total phenol content, flavanol measurements, iodine value, and seed oil content. Through rigorous experimentation and detailed analysis, this study unveils the intricate relationships between these biochemical markers and crucial agronomic traits, providing invaluable insights for cotton breeders and researchers alike. Delve into the methodologies employed, from experimental design to precise biochemical assays, ensuring reproducibility and reliability of the findings. Discover how these biochemical fingerprints can be used to identify superior genotypes, optimize breeding strategies, and ultimately enhance cotton production. This research not only illuminates the biochemical underpinnings of hybrid cotton performance but also paves the way for developing climate-resilient and high-yielding varieties, addressing the growing global demand for this essential crop. Whether you're a seasoned cotton breeder, a plant biochemist, or simply fascinated by the science of crop improvement, this book offers a compelling journey into the heart of cotton genetics and the future of sustainable agriculture, offering a comprehensive understanding of cotton breeding through biochemical characterization, and pushing the boundaries of agricultural innovation.
Captura de CO2 Mediante Adsorbentes Silíceos Mesoestructurados Funcionalizados con Grupos Amino
Characterization of histone modifying enzymes and their substrates in maize
Doctoral Thesis / Dissertation from the year 2007 in the subject Chemistry - Bio-chemistry, grade: Doctorate, University of Innsbruck (Institute of Molecular Biology), language: English, abstract: The maize ZmHda1 is a class II, HDA1-like histone deacetylase. ZmHda1 has been purified to homogeneity and found to be a 48 kDa monomeric protein (Brosch et al., 1996a). However, ZmHda1 specific antibodies can detect two other protein bands of molecular sizes of 84 and 65 kDa on immunoblots indicating that ZmHda1 exists natively in different molecular forms. These two protein forms of ZmHda1 are found in protein complexes of high molecular weights and they are enzymatically inactive (Pipal et al., 2003). Attempts to identify the protein components of the ZmHda1 protein complexes have been made. The second part of this study showed that histone methylation profile in maize embryos quantitatively and qualitatively changes as the germination progresses from 0 to 72 h. The total and chromatin unbound HMT activity decrease during the germination progress, while the chromatin bound HMT activity increases. This increase was most remarkable as an increase in methylation of H4K20 residue and to a lesser extent in mono- and tri- methylated H3K9 and dimethylated H3K36. With the progress of germination, the decrease in dimethylated H3K9 was remarkable. The decrease in H3K4 methylation and dimethylated H4R3 was less pronounced. Seven different histone methyltransferase activities could be separated from the 72h maize embryos; three of them were chromatin bound and four were found soluble in the cytoplasmic extract. Two of the chromatin bound activities, AI and AII2 methylate histone H3. AII2 showed H3K9 specificity and has a molecular size of 67 kDa. The third chromatin bound HMT activity, AII1, has a molecular size of 120 kDa and is H4 specific. Purification schemes could not yield purification of these activities to homogeneity; however, LC-MS/MS analysis of a chromatographic fraction containing the AII1 activity showed that it might have a homology to a putative SAM-dependent methyltransferase from Rhodobacter sphaeroides. Histone H3 is methylated by two activities from 72h maize embryos cytoplasmic extract; BI which has a molecular size of 30 kDa and another uncharacterized activity form. BII, from 72h embryos cytoplasmic extract, was purified to homogeneity using a series of FPLC chromatographic steps followed by native PAG. BII has been identified by nano-LC-MS/MS as a homologue of PRMT5, a type II PRMT and hence BII is referred to as ZmPRMT5.
Chemical Reactivity and Bioactivity Rates Of Marine Peptides Hemiasterlin Derivatives. Cancer Treatment Through Conceptual Density Functional Theory
Seminar paper from the year 2020 in the subject Chemistry - Bio-chemistry, , language: English, abstract: This study involved the assessment of the MNI2SX/Def2TZVP and the MNI2SX models to enhance the understanding of the structural composition of marine peptide Hemisterline derivatives A and B used in cancer treatment.The Conceptual Density Functional theory was used in the calculation of molecular properties of the system chemical descriptors during the study. Integration of the active molecular regions into their respective Fukui functions was used in the selection of radical, electrophilic, and nucleophilic attacks.Additionally, the proposed correlation between global hardness and the pKa was used as the basis of deriving accurate predictions for the pKa values while a homology technique was used in the prediction of bioactivity and bioavailability scores of the peptides under investigation.
Chemistry in a Shopping Trolley. Ascorbic acid Concentrations of fresh orange, fresh lemon, store-bought orange juice, store-bought lemon juice and a Berocca tablet
Scientific Study from the year 2016 in the subject Chemistry - Food Chemistry, grade: 12, , language: English, abstract: The concentration of Ascorbic acid in lemons, oranges, lemon juice, orange juice and a Berocca tablet were calculated to determine the best way to receive the recommended daily intake of Ascorbic acid. This experiment was conducted to decide the best source of Ascorbic acid for pregnant women, which is available from a supermarket. The concentrations were finalised by titrating the five substances and then calculating the concentration of Ascorbic acid. It was found that lemons had the highest concentration of Ascorbic acid, which was 0.6175mol/L. The fresh lemon was followed by the Berocca tablet, which had a concentration of 0.585mol/L, lemon juice with 0.5625mol/L, orange with 0.105mol/L, and finally orange juice, which had 0.095mol/L. While the lemon had the highest concentration, it was decided that fresh oranges were the best source of Ascorbic acid for pregnant women. These findings are significant because many pregnant women do not receive the recommended daily intake of Ascorbic acid, which has detrimental health impacts on themselves, and their child.
Chemistry of Heterocyclic Compounds
Scientific Study from the year 2018 in the subject Chemistry - Organic Chemistry, grade: A, , language: English, abstract: Heterocyclic chemistry is one of the largest branches of chemistry. Well over six million discrete heterocyclic compounds are known, reflecting their central and important role in Science and Technology. The usefulness of heterocycles is due to their combination of compact and robust molecular structures with a high degree of molecular diversity that results in properties, which can be finely adjusted to the needs of sophisticated applications. This is well illustrated by the functions of many naturally occurring heterocycles that are essential components of living cells, including DNA in which specific nitrogen heterocycles are directly responsible for encoding all genetic information. Morphine and quinine, two of the earliest compounds to be used in therapy and in use today, are both heterocyclic natural products. William Perkin's synthesis of the lucrative quinine molecule in 1856 led to the discovery of an important synthetic heterocycle, mauveine, and this laid the foundation of the synthetic dye industry. This in turn gave birth to the modern industry when in 1932 the antibacterial properties of the dye lead to the discovery of heterocyclic sulfapyridines. These antibacterial agents were the first major life saving synthetic drugs and they quickly had a dramatic effect on the quality of life.
Comparison of Honey Quality of Kangra and Bilaspur District of Himachal Pradesh
Academic Paper from the year 2015 in the subject Chemistry - Food Chemistry, , language: English, abstract: India is the second largest honey producer and exporter in the world, plays an important role in world honey production and trade. The total production of honey in India is approx. 27000MT per year and the maximum production of honey in India comes from the forests.In Himachal Pradesh the total honey production is about 120MT per year. Honey has been used by man in various ways since times immemorial. It contains more than so different substances but 95-99,5% of the total solids and sugars. The color, aroma, flavor, texture are the important quality characteristics of honey. Besides this, honey is prized for.
Compuestos de Coordinación de Manganeso(II) y Calcio(II) con 2,2'-Bipiridina y 1,10-Fenantrolina para su Uso Potencial en Sistemas de Fotosíntesis Artificial
Der Effekt unterschiedlicher Taurinkonzentrationen auf aktivierte B-Zellen
Wissenschaftliche Studie aus dem Jahr 2016 im Fachbereich Chemie - Biochemie, , Veranstaltung: Student der St.Elisabeth Hochschule, Bratislava in einem PhD-Verfahren, Sprache: Deutsch, Abstract: Experimentelle Untersuchung der Auswirkung von Taurin auf aktivierte B-Zellen. In Abhängigkeit von der Taurinkonzentration wurde die Aktivität in Form der Immunoglobulin-Produktion erfasst. Zur weiteren Untersuchung wurde ein Serotonin Antagonist zugegeben und die B-Zell-Aktivität verglichen.
Determining the Interaction of Cresyl Violet Acetate using Computer Modeling and Spectroscopy
Research Paper (undergraduate) from the year 2013 in the subject Chemistry - Organic Chemistry, Fairleigh Dickinson University, College at Florham, language: English, abstract: Science is always finding new innovative ways to help cure diseases like HIV, cancer, and Alzheimer's. Fluorescent dyes have been a way to trace certain genes within our DNA (deoxyribonucleic acid). It has been brought to our attention that cresyl violet acetate, an organic compound, stains blue when working with DNA, but stains purple when working with RNA. Cresyl violet also changes color based on differences in base pairing.With the increasing use of technology, computer modeling and spectroscopy have been used to analyze the interaction of cresyl violet when bound to DNA. The Molecular Operating Environment (MOE) computer modeling software was used to predict possible modes of interaction. The results were fairly constant, showing backbone interactions with the amine groups of cresyl violet. There was also hydrogen bonding predictions between cresyl violet and DNA. Intercalation, or ¿-¿ stacking was only predicted for adenine ssDNA with cresyl violet. Cresyl violets cationic character, allowed for pH to play a factor in its binding ability, and therefore it was determined that pH held at 7.2 - 7.4 were the best conditions. Dimerization was controlled using both low concentrations of cresyl violet and ¿-cyclodextrin. By tracing pH and dimerization we can compare results to docking. This is since docking was set for cresyl violet with a +1 charge and with monomers docking to the DNA.Scatchard plot analysis showed that binding constants are affected by concentration of cresyl violet, and the inhibition of electrostatic interactions and dimerization. The lower the concentration, the less binding because of free versus bound ligand availability. At high concentrations, dimerization is too high, inhibiting binding. The use of spermidine to prevent electrostatic interactions, proved to improve binding of cresyl violet to DNA. ¿-Cyclodextrin sequesters dimerization, which also improved number of binding site. This could suggest intercalation as a possible mode of interaction because more binding is present when both interactions are unavailable, however, more experimentation is needed to conclude that intercalation is in fact present.
Die Bestimmung des Glucosegehalts im Verlauf der Lagerung und Keimung von Kartoffelknollen
Facharbeit (Schule) aus dem Jahr 2011 im Fachbereich Chemie - Organische Chemie, Note: 1,0, Gymnasium München/Moosach (-), Veranstaltung: Leistungskurs Chemie (Bayern, G9), Sprache: Deutsch, Abstract: Gegenstand dieser Facharbeit ist die Bestimmung des Glucosegehalts in der Kartoffelknolle im Verlauf ihrer Lagerung und Keimung.Die wissenschaftliche Arbeit gibt zunächst Auskunft über die chemischen Grundlagen und über mögliche Nachweismethoden für Stärke und Glucose. Im Anschluss werden Stärke und Glucose als Bestandteile der Kartoffelknolle nachgewiesen. Es folgt die Beschreibung sowie die Analyse und die Auswertung einer Versuchsreihe, die die Entwicklung des Glucosegehalts während der Lagerung und Keimung der Kartoffelknolle bestimmt.
Discarded desiccant silica gel. Agent in prolonging the shelf life of Lakatan Banana
Forschungsarbeit aus dem Jahr 2019 im Fachbereich Chemie - Lebensmittelchemie, , Sprache: Deutsch, Abstract: The objective of this study is to determine if the discarded desiccant silica gel can be potential agent in prolonging the shelf life of lakatan banana (Musa acuminata). It seeks to answer the following questions: In which set up will the lakatan banana will prolong its shelf life? Is there a significant difference in the lakatan banana (Musa acuminata) in 2 set-ups after 7 days in terms of the following: pulp to peel ratio, Peel color and Total soluble solid (sugar content)?Shelf life extension is the holy grail for the fruit and vegetable industry. A huge amount of food is wasted as it goes off before it is eaten. Extension of shelf life of fruits and vegetables has several advantages it improves the quality, taste and texture of the food, it reduces food waste and associated. Chemical treatments include usage of hydrogen peroxide, chlorine-based solutions, peroxyacetic acid, organic acids, nitric oxide and Sulphur dioxide to retard browning reactions, inhibit ethylene bio synthesis, reduce respiration rate and water loss and reduce the incidence of post-harvest diseases. But these methods or treatments are too expensive or our farmers and may cause harm to our health.The result of this study is beneficial to our vendors of banana , because the result of this study will give them an idea on to what agent can be use in prolonging the shelf life of banana. The result of this study is also beneficial to consumers to make safe and informed some safe and cheap method which they can used to prolong or extend the shelf life of fruits in their own home.
Distribución vertical de carbono orgánico y densidad aparente en gleysol con petróleo intemperizado en la venta, tabasco
Tesis del año 2014 en eltema Química - Bioquímica, Nota: 0, , Idioma: Español, Resumen: Durante el periodo de sequia de mayo de 2013 se colectaron, a diferente Profundidades, 48 muestras de un gleysol localizado en la venta, tabasco, se realizaron estudios de humedad, densidad aparente, materia organica, carbono organico e hidrocarburos totales de petroleo de las muestras del gleysol influenciado durante 40 años por oleoductos y emisiones gaseosas procedentes del complejo procesador de gas la venta.
Eco-Friendly Filtration. Designing Next-Gen Air Filters from Herbal and Agricultural Waste for N2O Gas
Master's Thesis from the year 2025 in the subject Chemistry - Organic Chemistry, , language: English, abstract: With the growth of organized societies and the advent of hydraulic structures, aqueducts, and early drainage systems, anthropogenic contamination began to broadly impact water systems. The true turning point came with the Industrial Revolution. Fossil fuel combustion and large-scale manufacture as well as intensive chemical production rapidly expanded; never before had such volumes of emissions been released into the atmosphere, hydrosphere, and lithosphere.Pollution evolved from being a localized environmental burden to attaining dimensions of a crisis at a global scale in the modern era. Now a days the anthropogenic pollution is now even seen in rural areas. And the pristine surrounding because of the long-range transport. Like for example the microplastic found in the polar snow and deep marines shows the effect of human generated contaminations. Thus, what we initially thought as a accidental by product has now become a widespread environmental emergency that has become a serous risk to ecological system, biodiversity and public healt all over the world.
Effect of the presence of paracetamol in the culture media of Aspergillus niger on activity of peroxidase
Bachelor Thesis from the year 2022 in the subject Chemistry - Bio-chemistry, grade: 3.3, University of Cape Coast (Department of Biochemistry), course: Biochemistry, language: English, abstract: In this study, solid fermentation of Aspergillus niger with paracetamol in test culture media and no Paracetamol in the control media were carried out to generate Peroxidase. Effects of pH and temperature on peroxidase activity were determined by subjecting the enzyme to various pH and temperatures.Paracetamol, usually called acetaminophen, is a drug used to relieve moderate pain such as headache, migraine, nerve pain, toothache, period pain, and muscular pain. Paracetamol can relieve pain by lowering the production of prostaglandins in the brain and in the spinal cord. Overdose of paracetamol leads to loss of appetite, nausea, vomiting, sweating, and whitening of the eye. Peroxidase forms a network in the body that has both beneficial and adverse effects.Peroxidase has physiological functions that substantially contribute to immunity and several metabolic and signaling processes. However, under certain circumstances, they exert deleterious effects such as damage to macromolecules in the plasma and activate cell death.
Effects of temporary examination stress on biochemical parameters in academic students
Master's Thesis from the year 2016 in the subject Chemistry - Bio-chemistry, , language: English, abstract: The present study was designed to investigate the effect of temporary examination stress on some biochemical parameters in sera of fifty five apparently healthy undergraduate students with age range (19- 24) years and (23.9 ± 2.13 kg/m2) body mass index, they were from University of Baghdad, College of Science; specialty from Mathematic, Physics, Geology, Biotechnology Departments, and also from Al-Esraa College, Medical Analysis Department.To compare the results, blood samples were obtained from the undergraduate students in two days, the first day was a normal day (Nday) and the second day was after 7-15 days, in the morning before the written exam (Eday). Based on gender, blood types, Rh blood type, exam performance, and the first semester score, the students were classified into several subgroups.
Einfluss der Versorgung mit hefeverwertbarem Stickstoff auf das Aroma des Weines
Studienarbeit aus dem Jahr 2013 im Fachbereich Chemie - Lebensmittelchemie, Note: 1,0, Hochschule Geisenheim University, Veranstaltung: Seminar für Weinbau und Oenologie, Sprache: Deutsch, Abstract: Stickstoff (N) ist essenziell für den Stoffwechsel und die Vermehrung von Hefen. Durch N wird die Proteinsynthese der Hefe sowie die Zuckeraufnahme in die Zelle möglich. Somit ist Stickstoff ein unerlässlicher Nährstoff für die alkoholische Gärung des Mostes, den biologischen Säureabbau im Wein und der zweiten Gärung in Form der Versektung. Die Höhe der Stickstoffverfügbarkeit im Most hat somit einen direkten Einfluss auf die Gärung und die damit einhergehende Aromenbildung. Ein zu geringer Gehalt an hefeverwertbarem Stickstoff kann zu Gärproblemen mit der Folge von restsüßen Weinen führen. Zudem entscheidet die Höhe an hefeverwertbarem Stickstoff über erwünschte und unerwünschte flüchtige Gärungsprodukte (z.B. Ester und höhere Alkohole) sowie über die Konzentration an SO2-Bindungspartner. Ist der Gehalt an hefeverwertbarem Stickstoff zu gering, kann dies zur Bildung des nach faulen Eiern riechenden Schwefelwasserstoffs (H2S) führen. Aus H2S bildet die Hefe eine Vielzahl anderer schwefelhaltigen Aromastoffe wie z.B. die Thioessigsäureester. Daraus können durch langsame Hydrolyse, während der Lagerung, Mercaptane freigesetzt werden. Diese führen wiederum zu erneuten unerwünschten böchserartigen Fehlaromen im Wein. Der Gehalt an hefeverwertbarem Stickstoff und eine ausreichende Stickstoffversorgung im Most und Trauben ist damit ausschlaggebend für eine qualitätsorientierte Weinbereitung.
Evaluation of Lead in the Organs and Tissues of Domestic Chicken (Gallus gallus domesticus). Food Safety
Project Report from the year 2015 in the subject Chemistry - Food Chemistry, grade: A, University of Ibadan, course: Zoology, language: English, abstract: A study was carried out on the assessment of lead in the organs and tissues of domestic chicken (Gallus gallus domesticus) in Ibadan from August to September 2015. Ten (10) chickens (layers and broilers) expressed as samples 1-10 were purchased from different retailer markets (Bodija, Ojoo and Sango) within Ibadan City. The chickens were dissected to remove the intestine, liver, kidney, blood, feathers and muscles were oven-dried at 220 degree Celsius. The pulverized organ and tissues samples were acid-digested and analyzed for the heavy metal lead (Pb) using Buck Scientific Atomic Absorption Spectrophotometer (AAS). The results showed that the highest Pb concentrations in parts per million (ppm) were recorded in the liver (2.940+0.040), intestine (3.9800+0.500), kidney(3.6600+0.6000), feather (3.5900+0.06000), and muscle (3.400+0.4000) in sample 10, while the lowest concentration was recorded in the kidney (0.150+0.0300) in sample 1 all at Bodija Market . Analysis of Variance (ANOVA) revealed significance of the Pb metal in the organs and tissues of chickens at P< 0.05. Less than half of the samples had Pb concentration that exceeded the permissible limit of 0.1ppm set by FAO/WHO.
How does temperature and Benzalkonium Chloride affect the efficiency of cleaning products?
Scientific Study from the year 2018 in the subject Chemistry - Organic Chemistry, grade: A, , language: English, abstract: How does an increase in temperature and a change in concentration of cationic surfactant Benzalkonium Chloride affects the cleaning ability of different floor cleaners measured in terms of change in surface tension using the stalagmometric method?What makes a floor cleaner exhibit cleaning ability? The major ingredient in the production of floor cleaners is Benzalkonium Chloride (BKC). There are several other surfactants available but this is commonly found in most of the floor cleaners. BKC, a cationic surfactant, has had several uses since it was introduced. Developed by a group of German scientists in the 1910s as a germicide, it was first used medicinally as a preservative for hard contact lens solutions and skin disinfectant. Today, there are thousands of different products that contain this chemical.There are various methods like capillary rise, drop and analysis to find the surface tension of a liquid. However, all the methods require machines and apparatus that are not easily available and are also expensive. Therefore, the stalagmometric method was the only feasible method that also gave reliable results. In order to find the floor cleaners that were common a survey was conducted in the local residential area.