2,845 research outputs found

    Cystein-Mutanten der Cu,Zn-Superoxiddismutase und ihre Anwendung in Proteinelektroden für die Detektion von freien Sauerstoffradikalen

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    Das Enzym Superoxiddismutase (SOD) bietet wegen seiner hohen Reaktionsrate und seiner extrem hohen Substratspezifi tät große Vorteile für eine Anwendung als Superoxidbiosensor. In dieser Arbeit wurden durch molekularbiologische Methoden Mutanten der humanen Cu,Zn-SOD gewonnen, welche ein oder zwei zusätzliche Cystein-Reste enthielten, die eine einfache Immobilisierung des Proteins durch Bindung des Cystein-Schwefels auf Goldelektroden ermöglichten. Sechs solcher Mutanten wurden entworfen, exprimiert, aufgereinigt und elektrochemisch charakterisiert. Alle Mutanten konnten durch einen einfachen Inkubationsschritt auf Goldelektroden gebunden werden und zeigten ein quasi-reversibles elektrochemisches Ansprechen. Für eine Mutante wurde die Anwendung als Superoxidsensor genauer untersucht und für beide Teilreaktionen der Dismutation ein Ansprechen des Sensors auf das Radikal gefunden. Bei Verwendung einer Teilreaktion konnte die Empfindlichkeit herkömmlicher Monoschichtsensoren um etwa eine Größenordnung übertroffen werden

    An experimental platform for surface embedded SMAs in morphing applications

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    This article will address the modeling and control of surface embedded shape memory alloys (SMAs) for the camber modification of a hybrid morphing airfoil. An analytical model will be derived. The results of this models will be discussed and compared to the experiments. The advantages of this modeling approach will be highlighted and alternatives will be briefly revisited. This discussion will figure into the utility of these models in the sizing of a full scale prototype of a SMA actuated active trailing edge of an airfoil. Throughout this article the prototype specifications are detailed and the design choices will be discussed. Performance improvements stemming from the inherent nature of the SMAs will be analyzed. It will be shown in this article that through the use of forced convection the overall cycle time can be reduced

    Electron attachment to valence-excited CO

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    The possibility of electron attachment to the valence 3Π^{3}\Pi state of CO is examined using an {\it ab initio} bound-state multireference configuration interaction approach. The resulting resonance has 4Σ^{4}\Sigma^{-} symmetry; the higher vibrational levels of this resonance state coincide with, or are nearly coincident with, levels of the parent a3Πa^{3}\Pi state. Collisional relaxation to the lowest vibrational levels in hot plasma situations might yield the possibility of a long-lived CO^- state.Comment: Revtex file + postscript file for one figur

    A combined smart-materials approach for next-generation airfoils

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    This article will present a morphing wing actuated using both surface embedded Shape memory alloys (SMAs) and trailing edge Macro-fiber composites (MFCs). This combination enables the airfoil to simultaneously achieve large scale deformations at low frequencies as well as rapid actuation with a limited amount of displacement. Thereby not only can the shape of the airfoil be optimized in function of the current mission profile but also the shear layer can be influenced. Each actuator is modelled using both a finite element and/or an analytical model and the results will be verified experimentally

    Marrow adipose tissue expansion coincides with insulin resistance in MAGP1-deficient mice

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    Marrow adipose tissue (MAT) is an endocrine organ with the potential to influence skeletal remodeling and hematopoiesis. Pathologic MAT expansion has been studied in the context of severe metabolic challenge, including caloric restriction, high fat diet feeding, and leptin deficiency. However, the rapid change in peripheral fat and glucose metabolism associated with these models impedes our ability to examine which metabolic parameters precede or coincide with MAT expansion. Microfibril-associated glycoprotein-1 (MAGP1) is a matricellular protein that influences cellular processes by tethering signaling molecules to extracellular matrix structures. MAGP1-deficient (Mfap2(−/−)) mice display a progressive excess adiposity phenotype, which precedes insulin resistance and occurs without changes in caloric intake or ambulation. Mfap2(−/−) mice were, therefore, used as a model to associate parameters of metabolic disease, bone remodeling, and hematopoiesis with MAT expansion. Marrow adiposity was normal in Mfap2(−/−) mice until 6 months of age; however, by 10 months, marrow fat volume had increased fivefold relative to wild-type control at the same age. Increased gonadal fat pad mass and hyperglycemia were detectable in Mfap2(−/−) mice by 2 months, but peaked by 6 months. The development of insulin resistance coincided with MAT expansion. Longitudinal characterization of bone mass demonstrated a disconnection in MAT volume and bone volume. Specifically, Mfap2(−/−) mice had reduced trabecular bone volume by 2 months, but this phenotype did not progress with age or MAT expansion. Interestingly, MAT expansion in the 10-month-old Mfap2(−/−) mice was associated with modest alterations in basal hematopoiesis, including a shift from granulopoiesis to B lymphopoiesis. Together, these findings indicate MAT expansion is coincident with insulin resistance, but not excess peripheral adiposity or hyperglycemia in Mfap2(−/−) mice; and substantial MAT accumulation does not necessitate a proportional decrease in either bone mass or bone marrow cellularity

    Myriapoda at "Reserva Ducke", Central Amazonia/Brazil

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    Myriapoda contains the four recent classes Chilopoda, Diplopoda, Pauropoda and Symphyla. In total, 159 families, 2166 genera and >15162 species are known world-wide. Twenty-nine families, >93 genera and >401 described species occur in Amazonia. One-fifth of the families presently known in the myriapods are represented in Amazonia. About 3% of all described species live, and at least 9% of the species estimated to exist world-wide in Myriapoda are assumed to live in Amazonia. From the forest reserve 'Reserva Ducke' near Manaus, 22 families, 38 genera and 73 described species are known at present. The Chilopoda represent 5 families, 9 genera, 23 species and one undescribed morphospecies, the Diplopoda 13 families, 18 described genera, 14 species and 19 undescribed morphospecies, the Pauropoda 2 families, 7 genera, 31 species, and the Sympyla 2 families, 4 genera and 5 species. All names are liste
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