61 research outputs found
Catalytic coatings on stainless steel prepared by sol–gel route
Get PDFStainless steel (flat and microstructured) substrates have been coated with sol–gel catalysts made up of metal nanoparticles (Rh, Ni, Pt) dispersed on alumina and alumina–ceria supports. The aluminum monohydroxyde (boehmite) sols were synthesized by hot hydrolysis/peptization of an aluminum alkoxide (Yoldas method). It is shown that the rheological properties of the sol, especially the thixotropy, play a key role on the homogeneity and the quality of the film deposited on the metal substrate. The catalyst layers have a very good adhesion, a thickness which can be easily controlled (in the range 0.1 to 10 μm), a large specific surface area and a good mechanical and thermal stability
Comparison of Cholesterol Lowering Diets: Apple, Casein Cytochrom P450 protein and Cholesterol 7α Hydroxylase Activities in Hamsters
Get PDFLithogenic diet, casein and apple fiber diets were fed to hamsters for 3-5 weeks. For control group, animals were fed on normal Purina chow without any supplement. The cholesterol lowering effect of lithogenic diet, casein and apple diets were compared. After dietary regimen, animals were screened for any gall stone formation. The isolated liver microsomes were separated from animals and tested for the cholesterol-7α Hydroxylase (CH) enzyme activity measurement in all three groups. The control animals did not show any gall stone formation and their CH enzyme activities were normal. The lithogenic diet showed significantly enhanced CH enzyme activities while animals fed on casein and apple diet regimen showed moderate increase in microsomal CH enzyme activity indicated cholesterol lowering in liver. In conclusion, cholesterol 7α hydroxylase may be a biomarker of cholesterol status in the body and microsomal CH enzyme may be lowered down after treatment of casein and apple diets
Brief von Joseph von Laßberg an Emil Braun, 27.03.1831-04.12.1831 / Brief von Joseph Freiherr von Laßberg an Emil Braun vom 04.12.1831 - K 3123,56,5
No full textFrühere Signatur: K 3123,8,5Inhalt: Laßberg nimmt auf die im Briefwechsel mit Braun entstandene Missstimmung Bezug, will sich aber nicht näher dazu äußern. Dass der Tauschhandel zwischen der Münchener Hofbibliothek und ihm hinsichtlich seiner fünf arabischen Handschriften nicht zustande gekommen ist, verdrießt ihn. Dafür freut er sich über die Entdeckung des Annoliedes durch Richard Cleasby, von dem er eine Abschrift erhielt. Er bittet darum, die bereits früher erwähnte Teetasse mit einem Eppishauser Motiv bis zum Jahreswechsel fertigstellen zu lassen. Eine französische Handschrift der Parzival-Dichtung des Dichters Kyot kennt er nicht. - Erwähnte Personen: Schmeller, Johann Andreas; Cleasby, Richard; Kyot. - Erwähnte Orte: Eppishausen; München; Oxford. - Erwähnte Werke: Annolied; Chrétien / Li contes del Graal. - Vorbesitzer: Felgner, Gustav. - Edition: Emil Brauns Briefwechsel mit den Brüdern Grimm und Joseph von Laßberg / Hrsg. von Rudolf Ehwald. - Gotha : Perthes, 1891, S. 119-121, Anm. S. 16
Brief von Joseph von Laßberg an Emil Braun, 27.03.1831-04.12.1831 / Brief von Joseph Freiherr von Laßberg an Emil Braun vom 13.10.1831 - K 3123,56,4
No full textFrühere Signatur: K 3123,8,4Inhalt: Laßberg beschwert sich bei Braun über die Verzögerung seiner Rückkehr von der Italienreise und über das Ausbleiben von Nachrichten. Die Malerin Louise Purgold ist derzeit zu Besuch in Eppishausen. Auch Richard Cleasby war vor drei Wochen in Eppishausen, ebenso war die Familie von Haxthausen zu Besuch. Jacob Grimm ist acht Tage da gewesen und hat den dritten Band seiner Grammatik mitgebracht. Zuletzt war, sehr kränkelnd, Johann Leonhard Hug im Hause Laßberg zu Gast. - Erwähnte Personen: Purgold, Louise; Cleasby, Richard; Haxthausen a. d. H. Abbenburg ; Grimm, Jacob; Hug, Johann Leonhard; Homerus; Ittner, Joseph Albrecht von. - Erwähnte Orte: Eppishausen; Venedig; Mailand; Rom; Göttingen; Freiburg. - Erwähnte Werke: Deutsche Grammatik Theil 3 / von Jacob Grimm. - Vorbesitzer: Felgner, Gustav. - Edition: Emil Brauns Briefwechsel mit den Brüdern Grimm und Joseph von Laßberg / Hrsg. von Rudolf Ehwald. - Gotha : Perthes, 1891, S. 112-114, Anm. S. 16
Yeast entrapment in Duckweeds: Immobilization performance and biomass localization within the support particles
No full textDie Bedeutung von Fermentation, Photosynthese und Pyrophosphat für das Überleben von Pflanzen unter Sauerstoffmangel
Get PDFSauerstoffmangel in Pflanzenzellen führt durch Hemmung der mitochondrialen Atmung zur Akkumulation von NADH und zu ATP-Mangel. Reis kann, im Gegensatz zu Weizen oder Kartoffeln, längere Sauerstoffmangel-Perioden überstehen. Ziel dieser Promotionsarbeit war es, einige Aspekte des Primär-Stoffwechsels zu untersuchen, die für das Überleben solcher Stresssituationen verantwortlich sein können, wie die Ethanol-Gärung, die Photosynthese sowie die Nutzung alternativer Energiedonoren. Die Ethanol-Gärung ermöglicht es Pflanzen, NAD zu regenerieren, und so die glycolytische ATP-Bildung aufrechtzuerhalten. Tolerante Reis-Pflanzen bildeten unter Anoxie in Dunkelheit mehr Ethanol als sensitive Weizen-Pflanzen. Dieser Unterschied war allerdings nur im Spross nachzuweisen und resultierte aus hohen Aktivitäten der Gärungsenzyme sowie aus großen Substratmengen in Reis-Blättern. Mehr als 24 h Anoxie konnten aber auch vom Reis aufgrund von Substratmangel nicht überlebt werden. Wurden Pflanzen bei Anoxie belichtet, verbesserten sich die Überlebensraten erheblich. Die Ethanol-Bildung war deutlich verringert, so dass neben der Gärung lichtabhängige Energie-liefernde Prozesse vermutet werden. Allerdings verlief die Photosynthese unter Anoxie aufgrund von CO2-Mangel nur vermindert ab. Eventuell könnte zyklischer Elektronentransport unter diesen Bedingungen zusätzliches ATP produzieren. In der Vergangenheit wurde vermutet, dass Pflanzen unter Sauerstoffmangel für Phosphorylierungsreaktionen statt ATP auch PPi nutzen könnten. In transgenen Kartoffelpflanzen, die infolge von Überexpression der E. coli-Pyrophosphatase weniger PPi enthielten als Wildtypen, wurde unter Hypoxie-Bedingungen nachgewiesen, dass PPi als alternativer Energiedonor bei der Saccharose-Spaltung eine bedeutende Rolle spielt. Dagegen konnte in transgenen Kartoffelpflanzen mit drastisch verminderter Aktivität der PPi-abhängigen Phosphofructokinase keine Beeinträchtigung der Stoffwechsel-Leistungen unter Hypoxie gezeigt werden.Oxygen deficiency stress in plant cells leads through inhibition of mitochondrial respiration to an accumulation of NADH and a decrease in ATP content. Rice plants can survive oxygen deficiency better than wheat or potato plants. The aim of this PhD-work was to examine, which biochemical processes are responsible for plant tolerance against low oxygen stress. The studies were focused on the analysis of ethanolic fermentation, photosynthesis and the function of pyrophosphate (PPi) as an alternative energy source. By using ethanolic fermentation, plants can regenerate NAD and maintain ATP formation during glycolysis. Tolerant rice plants produced much higher amounts of ethanol during anoxia in darkness compared to sensitive wheat plants. The high fermentation rate mainly occurred in the shoots as a result of high activities of fermentative enzymes as well as high availability of carbohydrates. Nevertheless, rice plants could not survive more than 24 h of anoxia in the dark because of carbohydrate depletion. Illumination during anoxia extended survival of plants. Ethanolic fermentation rate was reduced during light exposure of plants, indicating that other energy-producing processes can compensate. However, it could be shown that the complete photosynthesis was slowed down during oxygen deficiency due to CO2 deficiency. It is likely that cyclic electron transport could at least partially contribute to ATP production during these conditions. In the past, it was speculated that PPi could replace ATP for phosphorylating processes during low oxygen stress. With transgenic potato plants expressing E. coli pyrophosphatase and therefore containing less PPi it was demonstrated that PPi is a significant alternative energy donor for sucrose cleavage during hypoxia. However, in transgenic potato plants with a reduction of synthesis and activity of PPi-dependent phosphofructokinase it could not be demonstrated that these plants suffer more from oxygen deficiency than the wildtype
A silicon based microsystem for continuous in vivo glucose monitoring using a new reversible measuring principle
No full textS.27-38In this paper the concept of an integrated silicon based radioactive sensor microsystem is presented. The sensor is designed for long term measurement of blood glucose concentration of diabetic patients. The sensor itself is implanted. It is controlled and read out by a small external part which contains mergy source, the signal processing circuit and a display unit. The sensor itself is a detector for electron radiation and it is able to measure the ß-activity of 14C labeled lectin molecules. The amount of the lectin molecules in the two measuring chambers changes in one proportional chamber and reversible with changing glucose concentration
Nitrogen-rich transition metal nitrides
Get PDFThe solid state chemistry leading to the synthesis and characterization of metal nitrides with N:M ratios >1 is summarized. Studies of these compounds represent an emerging area of research. Most transition metal nitrides have much lower nitrogen contents, and they often form with non- or sub-stoichiometric compositions. These materials are typically metallic with often superconducting properties, and they provide highly refractory, high hardness materials with many technological applications. The higher metal nitrides should achieve formal oxidation states (OS) attaining those found among corresponding oxides, and they are expected to have useful semiconducting properties. Only a very few examples of such high OS nitrogen-rich compounds are known at present. The main group elements typically form covalently bonded nitride ceramics such as Si3N4, Ge3N4 and Sn3N4, and the early transition metals Zr and Hf produce Zr3N4 and Hf3N4. However, the only main example of a highly nitrided transition metal compound known to date is Ta3N5 that has a formal oxidation state +5 and is a semiconductor with visible light absorption leading to applications as a pigment and in photocatalysis. New synthesis routes are being explored to study the possible formation of other N-rich materials that are predicted to exist by ab initio calculations. There is a useful interplay between theoretical predictions and experimental synthesis studies at ambient and high pressure conditions, as we explore and establish the existence and structure–property relations of these new nitride compounds and polymorphs. Here we review the state of current investigations and indicate possible new directions for further work
Säsongvariationer i isflöde på Nordenskiöldbreen, Svalbard
No full textGlobal warming leads to increased precipitation in the Arctic, as warmer air can carry more moisture. The consequence is that many arctic glaciers get steeper slopes over time as increased melt at their lower part causes thinning and increased solid precipitation in their upper regions leads to thickening of the glacier. Ice flow of glaciers is strongly controlled by the surface slope, where steeper slopes leads to increased ice flow. An altered flow regime of the glaciers can lead to unpredicted contributions to sea-level changes as more glacier ice is delivered to lower regions and eventually to the sea through calving of melt- runoff. Long-term measurements of ice-flow velocities are therefore crucial to receive a better understanding of how glaciers respond to climate changes in a temporal and spatial scale. This study investigates ice flow velocities measured over a period of 10 years between 2006 and 2015 on Nordenskiöldbreen, Svalbard. The poly-thermal outlet glacier is centrally located on Spitsbergen; the main island of the Svalbard archipelago (74N°,10°E /81N°,35°E). Ice-flow velocities are measured continuously using stand-alone single-frequency GPS receivers attached to 8 metal stakes along the central flow line of Nordenskiöldbreen. The Institute for Marine and Atmospheric research in Utrecht, the Netherlands (IMAU) has developed such GPS units to measure ice-flow velocities at low costs and all year-round. Ice flow velocities at the central-flow line of Nordenskiöldbreen for the period 2006-2016 are estimated to be between 40 and 60 m a-1. Results show that maximum ice flow velocities can reach up to 80 m a-1 and occur mainly in the beginning of July. The highest annual averaged velocity of 53.88 m a-1 was measured during summer 2014. Averaged ice-flow velocities show an increasing trend of about 1.78 m a-1 during summer seasons. Results are further compared with mass balance observations and temperature records to analyze how glacier systems respond to climate changes.Klimatuppvärmningen bidrar till att glaciärer blir tunnare och smälter snabbare. Ett varmare klimat är också orsaken till att snöfall ökar då varmare luft kan transportera mer fuktighet. Konsekvensen blir att glaciärer i arktiska områden får brantare sluttningar. Brantare sluttningar leder sedan till att glaciärer rör sig snabbare. Om glaciärer plötsligt rör sig snabbare uppstår möjligheten att havsnivån också stiger snabbare. Uppsatsen undersöker is-hastigheten från Nordenskiöldbreen. Nordenskiöldbreen är en glaciär på Spetsbergen, Svalbard som går ut i Adolfbukta innerst Billesjorden. Hastigheten uppmättes med hjälp av 13 GPS-stationer på glaciärens yta, placerade mellan 800 och 1200 meter över havsnivån. GPS-stationerna är utvecklade av Institut för Marin- och Atmosfär-undersökningar i Utrecht, Holland (IMAU) för att mäta glaciärens hastighet året runt till låga kostnader. Sedan 1997 har Institutionen för geovetenskaper vid Uppsala Universitet utfört flera mätningar på Nordenskiöldbreen för att mäta massbalans, isrörelse och miljöförändringar. Massbalans mätningar har visat att glaciären fick brantare sluttningar över den senaste tio-års perioden. Uppsatsen analyserar trenden för isrörelse vid Nordenskiöldbreen över de senaste tio åren. Dessutom är resultanterna jämförda med massbalans-analyser och temperaturmätningar från Svalbard Flygplats. Jämförelsen hjälper att förstå hur glaciärens system reagerar på klimatförändringar. De uppskattade hastighetsresultaten visar att Nordenskiöldbreen rör sig med en medelhastighet av 45-53 meter per år. Isrörelse kan nå upp till 80 meter per år och är främst förekommande under juli månad när temperaturen är hög. Detta producerar då mer smältvatten vilket driver upp vattentrycket vid glaciärens botten och leder till basal glidning
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