253 research outputs found
Constitution of the binary M-Sb systems (M = Ti, Zr, Hf) and physical properties of MSb2
No full textThis study is closely related to the chemical interactions in thermoelectric joints of a hot metal electrode with p- and n-type skutterudite. As a result of this work, a first and complete phase diagram has been constructed for the TiâSb system as well as partial phase diagrams (>65 at.% Sb) for the systems ZrâSb and HfâSb. Investigations are based on X-ray powder and single crystal analyses (determination of the crystal structure of Ti5Sb8with Zr2.6Ti2.4Sb8-type, space group I4122; RF= 0.032), electron probe microanalyses (EPMA) and differential thermal analyses (DTA). Physical properties were evaluated for the binary compounds MSb2(M = Ti, Zr, Hf) comprising electrical resistivity (from 4.2 K to 825 K), specific heat, thermal conductivity and thermal expansion coefficient (from 4.2 K to 300 K), Seebeck coefficient (from 300 K to 825 K) and elastic moduli at 300 K. These data will serve to evaluate the potential of MSb2compounds (M = Ti, Zr, Hf) for thermoelectric devices, where these phases predominantly appear in the diffusion zones of the hot metal electrode with p- and n-type skutterudite
Myelin basic protein in lipid-bound form induces experimental allergic encephalomyelitis and demyelination in Lewis rat.
No full textMyelin basic protein (MBP) was isolated from guinea-pig spinal cord in a form retaining the binding to all the myelin lipids. This new, lipid-bound and native-like preparation was used to immunize Lewis rats in complete Freund's adjuvant (CFA) in order to produce experimental allergic encephalomyelitis (EAE). The clinical features were compared with those of Lewis rats immunized with lipid-free MBP (LF-MBP), myelin, LF-MBP + octyl-POE (the non-ionic detergent used for the purification of LB-MBP) and octyl-POE alone. The clinical observation indicate that LB-MBP exerts an encephalitogenic activity on Lewis rats which is more intense than LF-MBP and includes demyelinating lesions in the central nervous system (CNS). The data suggest that LB-MBP is a new encephalitogenic antigen, which may induce more intensive immunization in rats and may be relevant in humans for autoimmune demyelinating diseases of the CNS
Induction of experimental autoimmune encephalomyelitis in rats and immune response to myelin basic protein in lipid-bound form.
No full textCicatricial pemphigoid. Immunofluorescence study
No full textLR: 20051117; PUBM: Print; JID: 0372755; 0 (Immunoglobulin A); 0 (Immunoglobulin D); 0 (Immunoglobulin G); 0 (Immunoglobulin M); 37341-29-0 (Immunoglobulin E); 9007-36-7 (Complement System Proteins); ppublishSource type: Electronic(1
Investigation of new high magnetostrictive materials
No full textMagnetostriktive Materialien, die bei niedrigem Magnetfeld eine hohe Magnetostriktion aufweisen, günstig in der Herstellung sind, dazu noch eine hohe mechanische Festigkeit und gute Duktilität besitzen, sind gute Kanditaten für industrielle Anwendungen als magnetomechanische Sensoren und Aktuatoren. Intermetallische Verbindungen, basierend auf der allgemeinen Formel 3d-Metall (Fe, Co) + Additiv (bis zu 25%, z.B.Ga, Al, Ge, Pd oder ähnliche) erfüllen diese Anforderungen recht gut.Diese Verbindungen haben alle recht ähnliche Phasendiagramme und kristallisieren in der A2, B2 oder DO3 Struktur. Die Idee diese Verbindung zu untersuchen basiert auf der Vorstellung dass die Reduktion der lokalen Symmetrie durch Substitution mit einem nicht-magnetischen Element vielleicht die Magnetostriktion erhöht.Der Schwerpunkt dieser Arbeit liegt in der Untersuchung der magnetischen und mikrostrukturellen Eigenschaften von Fe -basierten magnetostriktiven Materialien, die auf unterschiedliche Arten (Hochfrequenzschmelzen, "severe plastic deformation" (SPD), "melt spinning", "splat cooling" and "water quenching") hergestellt wurden. Zusätzlich wurde die Magnetostriktion sowohl von Fe-Mn und Ni-Ga Verbindungen, als auch über verschiedene Herstellungsarten produziertes CoFe2O4 untersucht.Strukturelle Eigenschaften, Gitterkonstanten, Kristallitgröße und Textur wurden über XRD Analyse bestimmt. Die Magnetischen Eigenschaften wurden entweder in einem Pulsfeldmagnetometer oder in einem Standard VSM festgestellt. Die Magnetostriktionsmessungen wurden entweder mit Dehnungsmessstreifen oder in einer kapazitiven Zelle gemessen.Bei der Untersuchung verschiedener Zusammensetzungen von Fe-Ga Bänder ("flakes") mit unterschiedlichen Abschreckraten wurde bei "Fe82.5Ga17.5 Bänder, das mit einer Abschreckgeschwindigkeit von 15 m/s gespritzt wurde, der höchste Magnetostriktionswert von 116 ppm gefunden. In der Probenserie "Fe-Ga rasch abgeschreckte Bänder wurde eine starke Abhängigkeit der Magnetostriktion mit der Abkühlrate festgestellt. Für "severe plastic deformed" Fe81Ga19 wurde eine Magnetostriktion von bis zu 67 ppm gemessen. Für langsam gekühltes polykristallines Fe81Al19 wurde eine Magnetostriktion von bis zu 62 ppm gefunden, wohingegen die Magnetostriktion der gespritzten Fe-Al Proben nur bis zu 30 ppm ergab.Die Probenserie Ni-Ga zeigte keine signifikante Verbesserung der Magnetostriktion, ab ca 7% Ga in Ni nahm die Magnetostriktion sogar ab.Die Fe-Mn Probenserie zeigte Magnetostriktionswerte bis ca. -70 ppm, man braucht aber ein Magnetfeld von mehr als 5 T um die Proben zu sättigen.Der höchste Magnetostriktionswert (-147 ppm) in der CoFe2O4 - Serie wurde an Proben festgestellt welche mit der "Combustion Method" hergestellt wurden.Low cost magnetostrictive materials that exhibit a large magnetostric¬tion at low saturation field combined with a high mechanical strength and a good ductility are of great interest for applications in magnetomechanical sensors and actuators. Intermetallics based on the general formula 3d-metal (Fe, Co) + additives - up to 25% (such as Ga, Al, Ge, Pd or similar) are interesting candidates for new soft magnetic materials with a reasonable high magnetostriction. These alloys have a very similar phase diagram and crystallize in the A2, B2 or DO3 structure. The idea here is that due the substitution with a nonmagnetic element the local symmetry is reduced which causes an increase of the magnetostriction.The main focus of this thesis is on the investigation of magnetic and microstructural properties of magnetostrictive materials based on alloys between 3d-metal Fe and additives - up to 25%, such as Ga, Al, Ni and Co using different production routes as high frequency induction melting, severe plastic deformation (SPD), melt spinning, splat cooling and water quenching. Additionally Fe-Mn and Ni-Ga alloys were also investigated.In contrast to metallic systems, polymer composites and CoFe2O4 prepared with different routes were investigated with respect to magnetostriction in this thesis.Structural properties lattice constant, crystallite size and texture were determined by using XRD analysis. Magnetic properties were measured using pulse field magnetometer or standard VSM. Magnetostriction mea¬surements were performed either by using standard strain gauge method or capacitance cell methods.Among different composition of Fe-Ga ribbons, with different quench¬ing rates, Fe82.5Ga17.5 ribbon, melt spun at speed 15 m/s, has highest mag¬netostriction value of 116 ppm. In Fe-Ga rapidly quenched ribbons a strong dependence of magnetostriction on quenching rate was found. For Fe81Ga19 SPD bulk alloy magnetostriction values up to 67 ppm were measured. Slowly cooled bulk polycrystalline Fe81Al19 material exhibits a magnetostriction value of 62 ppm. The magnetostriction in Fe-Al melt spun ribbons reached only values up to 30 ppm. The addition of Ga in Ni does not significantly en¬hance the magnetostriction and for higher values of Ga (up to 7%) addition magnetostriction decreases. The addition of Mn in Fe results in an increase in magnetostriction to -70ppm, but requires higher field value (more than 5T) to reach saturation. The highest value of magnetostriction found in CoFe2O4 ferrite prepared by combustion method, was -147 ppm
X-ray Peak Profile Analysis on the Microstructure of Al-5.9%Mg-0.3%Sc-0.18%Zr Alloy Deformed by High Pressure Torsion Straining
No full textThe microstructure of plastically deformed Al-5.9%Mg-0.3%Sc-0.18%Zr alloy has been
investigated. The severe plastic deformation has been performed by high pressure torsion
straining (HPT) up to 15 revolutions at room temperature. The microstructure as a function of
the number of revolutions is studied by X-ray diffraction peak profile analysis. It is concluded
that the HPT technique results in nanostructure even after 0.5 turn with very high dislocation
density. The crystallite size decreases and the dislocation density increases with the number of
revolutions, however, after five turns they go into saturation. The edge and the dipole
character of the dislocation structure becomes stronger with the increase of the number of
revolutions. The value of the crystallite size determined by X-ray peak profile analysis is a bit
smaller than the grain size obtained by transmission electron microscopy (TEM)
Naturally Occurring Phenols Modulate Vegetative Growth and Deoxynivalenol Biosynthesis in Fusarium graminearum
No full textInduction of experimental autoimmune encephalomyelitis in rats and immune response to myelin basic protein in lipid-bound form
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